JOHN A. BAYCno^r SWC<2E€«iUM TO Digitized by the Internet Archive in 2007 with funding from IVIicrosoft Corporation http://www.archive.org/details/commorganaly32allerich JOHN A. BAVCROF SUCCESSOH TO ALLEN'S Commercial Organic Analysis. AUTHORIZED EDITIONS. A Treatise on the Properties, Proximate Analytical Examination and Modes of Assaying the Various Organic Chemicals and Products employed in the Arts, Manufactures, Medicine, &c., with Concise Methods for the Detection and Determination of Impurities, Adulterations and Products of Decomposition, &c. Revised and Enlarged. By Alfred Allen, f.c.s., Public Analyst for the West Riding of Yorkshire and the City of Sheffield; Past President Society of Public Analysts of England, &c. Vol. I. Introduction. Alcohols, Neutral Alcoholic Derivatives, &c., Ethers, Vegetable Acids, Starch and its Isomers, Sugars, &c. Third Edition, v^ith numerous additions by the author, and revisions and additions by Dr. Henry Lepfmann, Professor of Chemistry and Metallurgy in the Pennsylvania College of Dental Surgery, and in the Wagner Free Institute of Science, Philadelphia, &c. 8vo. Cloth, $4.50 Vol. II — Part I. Fixed Oils and Fats, Glycerine, Nitro-glycerin, Dynamite and Smokeless Powders, Wool-Fats, D^gras, &c. Third Edition, Revised by Dr. Henry Leffmann, with numerous additions by the author. 8vo. Cloth, $3.50 Vol. II — Part II. Hydrocarbons, Mineral Oils, Lubricants, Asphalt, Benzine and Naphthalene, Phenols, Creosotes, &c. Third Edition, Revised by Dr. Henry Leffmann, with many additions by the author. Cloth, $3.50 Vol. II — Part III. Acid Derivatives of Phenols, Aromatic Acids, Resins, and Essential Oils. Third Edition, Rewritten and Revised by the author and Arnold R. Tankard, f.c.s. Cloth, $5.00 Vol. Ill — Part I. Tannins, Dyes and Coloring Matters, Writing Inks. Third Edition, Rewritten and Enlarged, by J. Merritt Matthews, Ph.D., Professor of Chemistry and Dyeing in the Philadelphia Textile School. Cloth, $4.50 Vol. Ill — Part 11. The Amines and Ammonium Bases, Hydrazines and Derivatives. Bases from Tar. The Antipyretics, &c. Vegetable Alkaloids, Tea, Coffee, Cocoa, Kola, Cocaine, Opium, &c. Second Edition. With numerous addenda. 8vo. Cloth, $4.50 Vol. Ill— Part III. Vegetable Alkaloids, Non-Basic Vegetable Bitter Principles. Animal Bases, Animal Acids, Cyanogen and its Deriva- tives, &c. Second Edition. 8vo. Cloth, $4.50 Vol. IV. Pvoteids and Albuminous Principles. Proteoids or Albu- minoids. Second Edition. Cloth, $4.50 P. BLAKISTON'S SON & CO., Medical and Scientific Publishers, ESTABLISHED 1843. IOI2 WALNUT ST., PHILADELPHIA. COMMERCIAL ORGANIC ANALYSIS A TREATISE ON THE PROPERTIES, PROXIMATE ANALYTICAL EXAMINATION, . AND MODES OF ASSAYING THE VARIOUS ORGANIC CHEMICALS AND PRODUCTS EMPLOYED IN THE ARTS. MANUFACTURES, MEDICINE WITH CONCISE METHODS FOR THE DETECTION AND DETERMINATION OF THEIR IMPURITIES, ADUL- TERATIONS, AND PRODUCTS OF DECOMPOSITION ALFRED H. ALLEN, F.LC, F.C.S. PAST PRESIDENT SOCIETY OF PUBLIC ANALYSTS PUBLIC ANALYST FOR THE WEST RIDING OF YORKSHIRE, THE CITY OF SHEFFIELD, AC. Second BMtion, IRevise^ an& BnlaraeO 1902 REPRINT WITH ADDENDA VOLUME 1 1 1— PART 1 1 AMINES AND AMMONIUM BASES, HYDRAZINES, BASES FROM TAR, VEGETABLE ^AL,K.ALPJDS ' ' :l/ PrfLLADELFHlA ^ ; -^^ ^ ^ P. BLAKISTON'S SON & CO 1012 WALNUT STREET 1907 JOHN A. BAYCROF SUCCESSOI? TO PREFACE TO VOLUME III.-PART IL It is ten years since the publication of the last edition of that part of Commercial Organic Analysis which treated of Alkaloids and Tar Bases. These subjects then occupied about 120 pages. In the edition now issued 570 pages have already been printed, and I feel reluctantly compelled to publish the subject-matter now ready as Part II. of Volctme III, leaving the sections on the less important Alkaloids and the chapters on Animal Bases, Cyanogen Compounds, Proteids, &c., to be issued separately as Part III. In Part IL, now published, I have endeavoured to describe fully and accurately such of the Organic Bases as have any practical interest, and to give reliable information as to their sources. The Amines, Hydrazines, and Pyridine and its Derivatives are now considered for the first time. The Antipyretics, and other synthetical remedies with which modern Chemistry has enriched medicine, are described fully, in cases where they fall appropriately within the scope of the present Volume ; and I believe the sections on Antipyrine, Antifebrin, Phenacetin, Thalline, &c., contain a resume of all published information on their respective subjects. In the Chapter on Vegetable Alkaloids I have spared no pains to render the more important articles as complete and trustworthy as possible, and in this endeavour have received most 58348 iv PREFACE. valuable assistance from Mr W. Chattaway, Mr A. J. Cownley, Mr R. A. Cripps, Mr D. B. Dott, Mr A. W. Gerrard, Mr 0. Hehner, Dr B. H. Paul, Mr M. J. Sheridan, Dr C. R. Alder Wright, and Mr R. Wright, who have kindly perused and corrected some of the more important sections. When it is borne in mind that the article on Aconite Bases occupies 44 pages, that on Atropine and its Allies 27, Coca Alkaloids 23, Opium Alkaloids Q7 , Cinchona Alkaloids 79, and Tea and Coffee 27 pages each, it is evident that these gentlemen had no light task. I have also to acknowledge the zealous assistance of Mr G. E. Scott Smith, Mr C. M. Caines, Mr G. S. A. Caines, and other workers in my laboratory, in researches on the Assay of Aconite Bases, the Deter- mination of Caffeine, and much similar original experi- mental work, the results of which will be found duly recorded. In the sections on Tea, Coffee, and Cocoa, which conclude the Volume and together occupy 73 pages, I have incorporated nearly every item of trustworthy information of a chemical nature within my knowledge, and I believe these articles will be found of service by many besides professional chemists. Part III., completing the work, will be published as soon as possible, and will, I hope, be followed at no distant date by a New Edition of the earlier Volumes. ALFRED H. ALLEN. 101, Leadenhall Street, London, E.G., 1st October 1892. CONTENTS. AMINES AND AMMONIUM BASES. PAGE ( Classification and Nomenclature of Amines, ... 1 monamines, 3 Distinction and Separation of Monamines, 4 ; Methyl- amine, 9 ; Dimethylamine, 12 ; Trimethylamine, 12 ; Ethylamines, 17. Ammonium Bases, 18 Tetrethylammonium Compounds, 19. HYDRAZINES. Hydrazine, 22 Imidazoic Acid, 24. Substituted Hydrazines, 25 Ethyl-hydrazine, 26; Phenyl-hydrazine, 27; Hydrazones, 30; Osazones, 30; Pyrazolones, 30; Antipyrine, 32. BASES FROM TAR. Classification of Tar Bases, 39 Aniline and its Allies, 40 Aniline, 43; Aniline-sulphonic Acids, 49; Nitranilines, 50; Toluidines, 51; Xylidines, 57; Cumidines, 59; Aniline Oils, 60; Anilides, 67; Acetanilide, 68; Benzanilide, 72; Substituted Anilines, 73; Dimethyl-aniline, 74; Dipheuyl- amine, 79; Amido-phenols, 80; Phenacetins, 81; Pheny- lene-diamines, 86; Benzidine, 88. VI CONTENTS. PAGB Naphthylamines and their Allies, 90 o-Naphthylamine, 91 ; )8-Naphthylamine, 92 ; Naphthyl- amine-sulphonic Acids, 92; Naphthylene-diamines, 93; Amidonaphthols, 94. Pyridine Bases, 96 Pyridine, 99; Piperidine, 106; Homologues of Pyridine, 107; Pyridine-carboxylic Acids, 110; Pyrrol, 113; lodol, 114. QUINOLINE AND ITS ALLIES, 114 Quinoline, 116; Antipyretics allied to Quinoline, 119; Thai- line, 120; Quinazolines, 122. ACRIDINE AND ITS ALLIES, 123 Acridine, 123; Phenanthridine, 126. VEGETABLE ALKALOIDS. Characters and Classification op Alkaloids, , , . 127 General Eeactions of Alkaloids, 130 Keactions of the Alkaloids with Acids, 130; Titration of Alkaloids, 130; Eeactions of the Alkaloids with Alkalies, 132 ; Saponification of Alkaloids, 133 ; General Precipi- tants of Alkaloids, 134; Colour-reactions of Alkaloids, 144; Physiological Tests for Alkaloids, 149. Isolation and Purification of Alkaloids, .... 161 Extraction by Immiscible Solvents, 154; Dragendorff's Method of Separating Alkaloids, 159. Constitution and Synthesis of Alkaloids, .... 163 Volatile Bases op Vegetable Origin, 170 Conine, 171; Assay of Hemlock, 176; Lupine Alkaloids, 178; Nicotine, 179; Tobacco, 184; Snuff, 193; Piturine, 194; Lobeline, 195; Sparteine, 197; Spigeline, 198. Aconite Bases, 198 Constitution and Characters of the Aconite Bases, 201; Aconi- tine, 207; Anhydro-aconitine, 213; Aconine, 214; Amor- phous Bases, 215; Pseudaconitine, 216; Veratric Acid CONTENTS. VU PAGE 218; Japaconitine, 220; Picraconitine, 221 ; Lyaconitine, 223; Acolyctine, 224; Myoctonine, 225; Atisine, 226; Assay of Aconite and its Preparations, 228; Toxicology of Aconite, 236. Atropine and its Allies. Tropeines, 243 Constitution of Atropine and its Allies, 244; Atropine, 247; Hyoscyamine, 249; Hyoscine, 250; Atropamine, 251; Belladonnine, 252; Homatropine, 253; Detection and Determination of Tropeines, 254; Belladonna, Henbane, and Stramonium, 262. Coca Alkaloids, 270 Cocaine, 273 ; Benzoyl-ecgonine, 282 ; Ecgonine, 283 ; Bases allied to Cocaine, 284; Amorphous Bases of Coca, 287; Coca Leaves, 290. Opium Alkaloids, 293 Constitution of Opium Bases, 294; General Characters, 300; Colour-reactions, 303; Separation, 305; Morphine, 309; Apomorphine, 319; Basic Associates of Morphine, 320; Codeine, 321; Cryptopine, 324; Narceine, 326; Narcotine, 327; Rhoeadine, 331; Thebaine, 331 ; Opium, 332; Meco- nin, 335; Meconic Acid, 336; Adulterations of Opium, 340; Assay of Opium for Morphine, 342; Tincture of Opium, 350 ; Compound Tincture of Camphor, 353 ; Toxicology of Opium and Morphine, 355. Strtchnos Alkaloids, 360 Strychnine, 361; Detection of Strychnine, 364; Toxicology of Strychnine, 372; Easton's Syrup, 376; Vermin-killers, 378; Brucine, 381; Nux Vomica, 384; Curare, 387. Cinchona Alkaloids, 391 Table of Cinchona Bases, 392 ; General Properties of Cin- chona Bases, 394; Quinine, 397; Quinine Sulphate, 406; Examination of Quinine Salts, 408 ; Citrate of Iron and Quinine, 418; Hydroquinine, 424; Quinidine, 425; Quinamine, 427 ; Cinchonidine, 428 ; Cinchonine, 431 ; Amorphous Cinchona Bases, 433 ; Alkaloids of Remijia Barks, 436; Cupreine, 438; Cinchona Barks, 440; Assay of Cinchona Barks, 449; Separation of Cinchona Bases, 453. Vlll CONTENTS. PAGE Berberine and its Associates, 461 Berberine, 461; Oxyacanthine, 465; Hydrastine, 467; Calumba Root, 471; Columbin, 472. Caffeine and its Allies, 472 Caffeine, 474; Isolation and Determination of Calfeine, 484; Theobromine, 492; Diuretin, 497; Tea, 499; Extract and Infusion of Tea, 505; Adulterations of Tea, 509; Ash of Tea, 510; Tannin in Tea, 515; Exhausted Leaves in Tea, 513; Facings of Tea, 521 ; Eecognition of Foreign Leaves in Tea, 522; Paraguay Tea, 526; Coffee, 527; Roasting of Coffee, 530; Factitious Coffee, 535; Chicory, 538 ; Adulterations of Coffee, 539 ; Coffee Extract, 553 ; Kola Nuts, 554; Guarana, 555; Cocoa and Chocolate, 555; Cocoa Nibs, 557; Commercial Cocoa, 561; Essence of Cocoa, 562; Analysis of Cocoa, 564; Cacao Butter, 568. PLATES, 572 INDEX, 573 ADDENDA (issued with the reprint of 1902), 583 AMINES AND AMMONIUM BASES. WuRTZ, in 1848, pointed out that one of the hydrogen atoms of ammonia, HgN, could be replaced by ethyl, CgHg, and shortly afterwards A. W. H o f m a n n proved that the substitution by ethyl and other alkyl radicals could be extended to the second and third atoms of hydrogen, the new bodies thus produced being powerfully alkaline and in other respects closely resembling ammonia itself. H o f m a n n called these new bases amines, and proved them to be the simplest members of a numerous class of synthetically producible compounds. He classified them as primary, secondary, and tertiary amines, according as one, . two, or all three of the hydrogen atoms of the ammonia- molecule were replaced by alcoholic or alkyl radicals. As these atoms of hydrogen may be, and very often are, replaced by two or more different organic radicals, m i x e d amines exist, and are capable of numerous metameric modifications. Thus a base having the empirical formula CgH^gN may have any one of the five following constitutions : — 1. Amyl-amine, H VN H j C^Hc 2. Butyl-methyl-amine, CHg J> N H C3H7 3. Propyl- ethyl-am ine, CgH^ J-N H C3H,) 4. Propyl-dimethyl-amine, .... CH3 > N CH3J 0. Diethyl-methyl-amine, .... CgHg I N CH3) VOL. III. PART II. A NOMENCLATURE OF AMINES. Of these raetameric bases,^ the first only is a primary monamine •, the second and third are secondary amines ; and the fourth and fifth tertiary bases. They could be distinguished by their behaviour with ethyl iodide, nitrous acid, and the other reactions described on page 4 et seq. The hydrogen of ammonia may also be replaced bj- an acid radical, such as acetyl or benzoyl, when the resultant com- pound no longer possesses basic properties, and is termed an amide (e.g.^ acetamide, CgHgO.NHg). Mixed compounds also exist, such as CH3) ftOVN; which may be called either methyl-acetamide or acetyl- methylamine. Bases are also known which are derived from the replacement of certain of the atoms of hydrogen in two, three, and even four associated molecules of ammonia, the products being called respectively diamines, triamines, and tetramines, which closely resemble the monamines in their general characters. The following are examples of such bases : — Monamines— Phenylamine {Aniline). (CeHg) H H Diethylamine. (CA) ) (CA)) (CH3)) U CA U (CH3)U 3 H ) (CHjj Trimethylamine. (CH3) (CH3) (CH3) Diamines — Phenylene-diamine. H„ Diethylene-diamine. (C,H,)" U^ (C,HJ'j Triethylene-diamine. (C^H,)") (C,H/U-, Thiamines — Diethylene-triamine. (CA)"Pa (CA)"j Triethylene-triamine. H3 (C^H,)" (C^H,)" (CA)" N3 Tetramines — Triethylene-tetramine. He (CAV ^ It is evident that the formulae in the text do not exhaust all possible modifications of the base CgHigN, as they do not take into account the various isomeric modifications of which propyl, butyl, and amyl are susceptible. }"■ NATUKAL AMINES. 8 Interesting bases are also obtainable by the substitution of organic radicals for the hydrogen atoms of H3P, HgAs, and HgSb. The majority of the known bodies of the amine class are synthetical compounds of great scientific but little practical interest. Some few amines have been found to exist naturally in plants (e.g., trimethylamine, conine), and others are met with in animal fluids (e.g., urea), or the products of the decomposition of animal matters (leucine, glycocine). The tar-bases may be regarded as belonging to the amine class, aniline and toluidine being primary, and pyridine and q u i n o 1 i n e tertiary monamines. Pi peri dine, conine, and sarcocine are examples of secondary monamines; while urea and diamidobenzene may be regarded as diamines, and biuret and guanidine as triamines. Choline and n e u r i n e are related to the tetra- alkyl-ammonium bases. The monamines may be advantageously considered at the present stage, but the majority of the amine bases will be more conveniently described in other chapters. MONAMINES. These bases are derived from one molecule of ammonia by the substitution of one or more of the hydrogen atoms by an equivalent number of alkyl radicals. The first body obtained of this class was ethylamine, CgHg.NHg, prepared by Wurtz in 1848 by distilling ethyl cyanurate with caustic potash. Methylamine, CHg.NHg, was obtained by the same chemist in the following year, by the distillation of methyl isocyanate (acetonitrile) with caustic alkali :— 2K0H + CH3.N.CO = KgCOg + CH3.NH2 . Hofmann obtained the monamines by the reaction of an alkyl iodide on an alcoholic solution of ammonia. The reaction is not a simple one, all three monamines being formed together with a tetra-alkylated ammonium base. Thus, when ethyl iodide is heated with alcoholic ammonia to 100° in a sealed tube, there are obtained : — Hydriodide of ammonia, . . . HgNjHI = H^NI „ monoethylamine, . (C2Hj5)H2N,HI = (C2H5)H3NI „ diethylamine, . (C2H5)2HN,HI = (C2H5)2H2NI triethylamine, . (C2H5)3N,HI = (C2H5)3HNI Iodide of tetra-ethyl-ammonium,. (CgHg^gNjCg^sI = (^2^5)4^^ Similar products result when bromide or chloride of ethyl Is substituted for the iodide, except as to the relative proportions of the amines obtained. Thus chloride of ethyl produces almost exclusively EtHgNCl, with small quantities of EtgHgNCl and 4 FORMATION OF AMINES. Et^NCl ; ethyl bromide gives chiefly EtHgNBr, with very appreciable quantities of EtgHgNBr and EtgHNBr, but very little Et^NBr ; while ethyl iodide produces EtHgNI, EtgHgNI, and EtgHNI in about equal proportions, as well as very appreciable quantities of Et^NI (Groves, Jour. Chem. Soc, xiii. 331). A similar series of products is obtained by heating iodide, bromide, or nitrate of methyl with a solution of ammonia in methyl alcohol. When the methyl nitrate and ammonia solution are used in equivalent proportions for the reaction — MeNOg^- H3N = MeH2N,HNOg, monomethylamine is the chief product, though more or less of each of the more highly substituted pro- ducts is also formed. With excess of methyl nitrate, the nitrate of tetramethyl-ammonium, Me^N.NOg, is produced in large excess, and the same quaternary compound is formed if methyl bromide or iodide be substituted for the nitrate. The complex nature of the products obtained by treating alkyl iodides, &c., with alcoholic ammonia is due to the tendency of the amines first produced to react on the remaining portions of the alkyl iodide or other salt to form ammonium iodide and more highly substituted amines. Thus ; — H3N + C,H,I = (CA)HsNI . (C A)H2N + C^H.I = (C2H,)H2NI (C^HJ^HN + C^H.I = (C2H,)3HNI (CA)3N + C,H,I = (CA)4NI The hydriodides of the amines similarly react with alkyl iodides in presence of ammonia to form ammonium iodide and more highly substituted amines. From these reactions it follows that the hydriodide of diethyl- amine, for instance, may be obtained by heating the bromide or iodide of ethyl with a calculated amount of mono-ethylamine in a sealed tube. A great variety of mixed amines may be obtained by precisely similar means. Distinction and Separation of Primary, Secondary, and Tertiary Monamines. a. If an amine be heated to 100°, under pressure, with an excess of alkyl iodide, a quaternary iodide will at length be formed, and the problem whether the original base was a primary, secondary, or tertiary amine will be solved by comparing the composition of the ultimate product with that of the original base or its hydriodide. Thus, if methyl iodide has been the alkylising agent employed, the iodide of the compound ammonium ultimately obtained will differ from the hydriodide of the original SEPARATION OF AMINES. 5 base by SCHg, if the amine was primary ; by 2CH2, if secondary ; and by CHg, if tertiary. h. The following is an outline of the method devised by A. W. Hofmann for the separation of the mixed amines resulting from heating ethyl iodide with alcoholic ammonia : — The product of the reaction is filtered from ammonium iodide, which is nearly insoluble in the alcoholic liquid, and is evaporated to dryness to get rid of excess of alcohol, free ammonia, and unchanged alkyl iodide. The residue is then distilled with caustic potash, when the hydriodides of the amines are decomposed, the bases volatilising, while the iodide of the tetra-alkylated ammonium base remains in the retort unchanged by, and insoluble in, the strong potash solution. The mixture of amines is conducted over caustic lime, and then condensed by passage through a well-cooled tube. The bases are then treated in a flask with one and half times their weight of ethyl oxalate (previously dried over calcium chloride), which is added gradually through a tapped funnel. This has no action on triethylamine or other tertiary bases, but converts diethylamine into liquid ethyl diethyl-oxamate, and mono-ethylamine into solid d i e t h y l-o x a m i d e,^ according to the following equations : — (0^)20^0,+ 2(C2H,)NH, = C,0, 1 NH(§H j + 2(CA)0H Ethyl oxalate. Ethylamine. Diethyl-oxamide. Alcohol. 2. (C,H,),CA + (CA)2NH = C,0,{ Og^^«^^^+(CA)OH Ethyl oxalate. Diethylamine. Ethyl Diethyl-oxamate. AlcohoL The liquid gets very hot, but for the completion of the reaction the mixture should be heated to 100° for several days in a closed vessel. The triethylamine, which has taken no part in the reaction, is then distilled ofif on the water-bath. The residue is well cooled, and the solid oxamide separated from the liquid oxamate by pressure.2 On subsequent distillation with caustic potash, * Diethyl oxamide may also be separated from the ethyl diethyloxamate by cold water, in which the former dissolves easily, the latter very sparingly. If hot water be used, the separation is more perfect and the residual oxamate quite pure ; but some of it suffers hydrolysis and goes into solution as diethyloxamic acid. ' Some ethyl monoethyloxamate, C2O2 -j ijg c H ^^ always formed from the primary amines in this reaction. 1. 6 SEPARATION OF AMINES. these compounds yield the primary and secondary amines respec- tively : — 1. C202(NH.C2H5)2+2H.(OK)=C20,(OK)2+2H(NH.C2H6) 2. C2O2 I g^gA) +2H.(OK) = C202(OK)2+H.N(C2H,^^ The foregoing process is available, with certain modifications in detail, for the separation of the amines of methyl and other homo- logues of ethyl, and, in fact, is of general application for the separa- tion of primary, secondary, and tertiary amines; the first class forming oxamides, the second oxamic ethers, and the third being unacted on by ethyl oxamate. An important modification in the foregoing method has been made by I) u v i 1 1 i e r and B u i s i n e (Ann. Ghim. Phys., [5], xxiii. 289), who operate on an aqueous solution of the bases. Under these conditions, the primary amines are converted by ethyl oxalate into insoluble or sparingly soluble oxamides, while the secondary and tertiary bases are unchanged, or at any rate remain wholly in solution. After separating the oxamides by filtration, the mother- liquor^ [is boiled for some time, which causes the hydrolysis of the ethyl diethyloxamate with formation ofdiethyloxamic acid, (C2H5)2N.C202.0H, and the further change of this into the acid oxalate of diethylamine, (C2H5)2HN.H2C204.^ This salt separates on cooling, and yields the free base on distillation with alkali. The filtrate] is distilled with potash, the bases dried by caustic potash, and dissolved in absolute alcohol. On adding ethyl oxalate to this solution the secondary amines are converted into oxamic ethers, while any remaining primary amines are converted into the corresponding oxamides. After allowing the mixture to stand for twenty-four hours to complete the reaction, the alcohol and unchanged tertiary bases are distilled off on the water-bath The oxamates remaining in the retort may be converted into calcium salts by treatment with milk of lime, or the secondary bases at once liberated and recovered by distillation with caustic potash.^ ^ The treatment described in the brackets is optional, and chiefly of advan- tage in the separation of ethylamines. ^ The conversion into calcium salts is especially suitable for the treatment of the ethylamines. The precijatated calcium diethyloxamate and monoethyl- oxamate are filtered ofl", and the liltrate treated with alcohol, which precipi- tates the remainder of the calcium salts. The precipitates are treated with boiling water, when the monoethyloxamate dissolves, and is deposited again on cooling in large crystals, which on distillation with potash yield ethylamine. On concentrating and cooling the mother-liquors, calcium diethyloxamate separates. It is recrystallised from alcohol, washed with ether to remove any adhering oxamide, and distilled with potash, when it yields pure diethylamine. REACTIOifS OF AMINES. 7 Duvillier and Buisine have applied this method to the analysis of the complex mixture of amines present in commercial trimethyl- amine from vinasses (page 13). A. MUller {Bull. Soc. Chim.^ xlii. 202 ; Jour. CJiem. Soc, xlviii. 501) has described a method for the separation of amines based on much the same principle. The primary, secondary, and tertiary monamines may also be distinguished by the following reactions : — c. If a primary monamine be boiledwithalcoholicpotash and chloro- form, the characteristic and highly disagreeable odour of the corre- sponding carbamine or isonitrile is evolved, according to the reaction :— MeNHg + CHCIg + 3KH0 = MeNC + SHgO + 3KC1. d. If a primary fatty monamine be dissolved in a mixture of equal measures of alcohol and carbon disulphide, and the liquid then boiled down to one-half, a thiocarbamate will be formed thus:— 2MeNH2+CS2 = MeNH.CS.S.NMeH3. If the resultant liquid be boiled with a solution of mercuric or ferric chloride, a pungent odour of mustard oil will be produced, owing to the formation of an alkyl iso-thiocyanate :^ — MeNH.CS.S.NMeHg -f HgClg = HgS + MeNCS + NMeHsCl. e. Nitrous acid con^evts primary fatty monamines into the corre- sponding alcohols :— MeHgN -f NO.OH = Me.OH -\- OH2+ Ng. Aromatic primary amines {e.g., aniline) are converted by nitrous acid into diazo-compound s : — PhNH2+N0.0H = PLNiKOH + HgO. Secondary amines, whether fatty or aromatic, are converted by nitrous acid into nitrosamines, thus : — Me2NH + NO.OH = MegN.NO + HgO. The nitrosamines are yellow liquids, of neutral character and aromatic odour, volatile without decomposition in a current of steam. Weak reducing agents convert them into hydrazines (page 27) j but by more powerful hydrogenising agents, or by warming with alcohol and hydrochloric acid, they are reconverted into the original secondary amines. Nitrous acid has no action on tertiary fatty amines. It converts most tertiary aromatic amines into nitroso-derivatives which still possess basic properties. In practice, the action of nitrous acid on the amines is best effected by distilling their hydrochlorides with a strong solution of potassium or sodium nitrite. If a mixture of the hydrochlorides of the three methylamines be thus treated, the monomethylamine is destroyed (with formation of methyl alcohol, which will be found * In the case of aromatic primaiy amines, the product is usually a thio-urea, which requires to be treated with phosphoric pentoxide to obtain the iso-thio cyanate. 8 ASSAY OF MIXED AMINES. in the distillate), dimethylamim is converted into dimethyl- nitrosamine, which distils,^ while the hydrochloride of tri- methylamine remains in the retort (mixed with excess of the metallic nitrite), and on distilling it with caustic alkali the free base can be obtained. /. Both 'primary and secondary monamines react with aldehydes to form indifiPerent bodies. The reaction between oenanthol and mono- and di-methylamine respectively is as follows : — H2.N.GH3 + CeHi3.CH0 = HgO -f C6H13.CH.NCH3 ; and 2HN(CH3)2 + CeH,3.CH0 = H^O -f C6H,3.CH[N(CH3)2]2. This reaction has been utilised by Schiff (Annalen, clix., 158) for the volumetric assay of amines. The base is dissolved in benzene, fused calcium chloride added, and then a standard solution of oenanthol in benzene dropped in from a burette as long as water continues to separate. Each addition of the oenanthol solution produces a turbidity from separation of water, but this is absorbed by the calcium chloride on gentle agitation. As a primary amine reacts with twice as much oenanthol as the corresponding secondary amine, the proportions of the two in a mixture can be estimated from the result of the titration, provided the mean combining weight of the mixture be known, or ascertained in a separate experiment by titration with standard acid. g. The acidferrocyanides of the tertiary amines are remarkably insoluble in water. They are precipitated on adding potassium ferrocyanide to the solutions of the amines acidulated with hydrochloric acid. The bases can be recovered from their ferro- cyanides by treating the precipitate with solution of cupric sulphate, filtering, and removing the sulphuric acid and excess of copper from the filtrate by baryta-water. Generic Characters of Monamines. The monamines, as a class, are readily volatile liquids, of lower specific gravity than water. Their boiling-points rise with the number of carbon atoms in the molecule. They are inflammable, burning with a yellow flame ; and the lower members dissolve with great facility in water, forming strongly alkaline liquids of an ammoniacal odour. From their solutions, ethylamine and the higher homologues can be separated by saturating the liquid with caustic potash. By boiling the aqueous solutions of the free * On separating the nitrosamine, which forms a yellow oil, from the aqueoui distillate, treating it with aqueous hydrochloric acid, and then passing hydro chloric acid gas till the liquid is homogeneous, the hydrochloride of the secondary amine is formed, and may be obtained by evaporation of the solution. REACTIONS OF MONAMINES. 9 bases, or of their salts after adding excess of lime or fixed caustic alkali, the monamines can be completely volatilised, and con- densed again in water or acid, and titrated in the same manner as ammonia. The monamines are all powerful bases, closely resembling ammonia in their general characters. They form cry stalli sable salts, and yield chloroplatinates, chlor- a u r a t e s, and alums, exactly similar in characters and consti- tution to the corresponding compounds of ammonia. The mona- mines precipitate magnesium salts, but the precipitated mag- nesium hydroxide dissolves in the amine hydrochloride, forming a double salt from the solution of which phosphate of sodium precipitates an amino-magnesium phosphate. The amines thus behave exactly in the same manner as ammonia. The only amines (not described in other chapters) requiring detailed consideration are the primary, secondary, and tertiary monamines of methyl and ethyl. These bodies are typical of the amines generally, and most of the statements made respecting them would be true of all the bodies of the class. Their aqueous solutions dissolve silver chloride, and behave in much the same manner as ammonia with metallic salts ; but there are some interesting differences, as shown in the table on next page, from which it will be seen that certain of the precipitates which are soluble in excess of ammonia are undissolved by the amines, and vice versa} In all cases a solution of aluminium phosphate in hydrochloric acid behaves similarly to a solution of aluminium chloride (Taylor). Methylamine. Monomethylamine. CH3) H J Methylamine exists ready-formed in Mercuvialis annua and M. perennis, and, as obtained (in an impure state) from these plants, was formerly known as mercurialine. It also exists in herring-brine, coal-tar, bone-oil, and the products of the distilla- tion of wood,^ beetroot molasses (vinasses), and certain alkaloids * The author is indebted to Leo Taylor for repeating and enlarging on the experiments of Vincent, on whose observations the table is chiefly founded. Several blanks in the observations of Vincent have been filled by Taylor. ^ The presence of the amines of methyl in pyroligneous acid and wood spirit is probably due to the reaction of acetone and ammonia: — CgHgO + NHs™ C2H40 + (CH3).NH2. This equation has been experimentally verified. 10 REACTIONS OF AMINES WITH METALS. Metallic Salt. Ammonia. EthylamiTie. Methylamine. Dimethyl- amine. TrimethyU amine. {CH3)3N Aluminium. Insoluble (nearly). Soluble. Soluble. Soluble. Soluble. Cobalt. Blue precipi- tate ; sol- uble in ex- cess to brown solution. Insoluble. Blue; insol- uble in excess ; turned brownish on heating. Blue; insol- uble in excess ; turned brownish on heating. Blue; insol- uble in excess ; turned brownish on heating. NickeL Soluble in excess to violet-blue solution. Insoluble. Apple-green ; insoluble in excess. Apple-green ; insoluble in excess. Apple-green ; insoluble in excess. Zinc Very soluble. Soluble. Soluble in large ex- cess ; re- ppted on heating. Soluble in large ex- cess; re- ppted on heating. Soluble in very large excess ; reppted on heating. Cadmium. Soluble. Insoluble. Insoluble. Insoluble. Insoluble. Silver. Brownish ; very sol- uble in ex- cess. Brownish ; soluble in large ex- cess ; re ppted on warming. Brownish ; soluble in large ex- cess; re- ppted on warming. Dirty brown ppte changmg to black ; sol. large excess to dark solu- tion ; re- ppted on warming. Cupric Blue ; sol- uble in excess to deep blue solution. Soluble with difficulty in excess. Blue ; soluble in large excess to deep blue solution ; reppted dirty brown on boiling. Blue ; partly soluble in large ex- cess ; re- ppted dirty brown on boiling. Blue ; partly soluble in large ex- cess ; re- ppted dirty brown on boiling. Mercuric. White. ' White ; in- soluble. White; sol- uble in much water. Yellow ; changing to very pale yel- Stannic. Insoluble. Very soluble in excess. ... Soluble. Soluble. Antinionic. ... ... ... Soluble. Soluble in large ex- cess. Gold. Insolubla Soluble. Brownish yellow ppt; readily sol- uble in excess to orange-red liquid. Yellow pre- cipitate ; soluble in excess to brown liquid. Ruthenium. Insoluble. Soluble ... ... .. Lead. Insoluble. ... Insoluble. Insoluble. Insoluble. METHYLAMINE. 11 (e.^., morphine, codeine). It is also produced when caffeine is boiled with baryta-water, and by heating hydrochloride of tri- methylamine to 285°, when methyl chloride and trimethylamine volatilise, and methylamine hydrochloride (mixed with some ammo- nium chloride) remains. Methylamine may be prepared by the action of alcoholic ammonia on methyl iodide, but in this case dimethylamine and trimethylamine are also produced (page 3), and the main pro- duct is iodide of tetramethyl-ammonium. Methylamine is best obtained pure by treating one equivalent of acetamide with two equivalents of bromine, and then adding a 10 per cent, solution of caustic potash till the colour of the bromine has nearly dis- appeared : — C2H3O.NH2 -f Brg -f 2KH0 = CgHsO.KBrK -f KBr + 2H2O . Three additional equivalents of caustic potash are now dissolved to a 10 per cent, solution, and heated in a retort to 70° C. The product of the first reaction is then gradually added through the tubulure. The gases evolved are collected in hydrochloric acid, and on evaporating the solution a mixture of the hydrochlorides of ammonia and methylamine is obtained,^ from which the latter only is dissolved by absolute alcohol. On distillation with caustic alkali or slaked lime the salt yields the base, quite free from di- or tri-methylamine. Methylamine boils only a few degrees above zero, and hence is a gas at ordinary temperatures. One volume of water at 12°'5 C. dissolves 1150 measures of the gas, and hence it is more soluble even than ammonia, which methylamine closely resembles in odour and general characters, but is distinguished by its ready inflam- mability — a property even possessed by its concentrated aqueous solution. It burns with a yellow flame, forming carbon dioxide water, nitrogen, and hydrocyanic acid. On passing a succession of electric sparks through methylamine, hydrocyanide of methylamine is produced, and this is decomposed by a continuation of the treatment, with formation of a tarry deposit. When passed through a red-hot tube, methylamine is decomposed with formation of hydrogen and ammonium cyanides, methane, and hydrogen. The behaviour of methylamine with metallic solutions (page 10; and various other of its reactions have already been described. It forms a series of readily crystallisable salts. The chloro- ^ The reaction which occurs is very complex (A. "W. H f m an n, Ber,, xv. 765), but the main decomposition may be expressed as follows : — CH3.CO.NKBr + 2HOK = CO(OK)2+KBr + CH3.NHj. 12 DIMETHYLAMINE. plaiinate, (KeH^'N)2PtC\Qy is insoluble in alcohol, but soluble in boiling water, crystallising on cooling in beautiful golden-yellow scales. A method for the proximate analysis of the bases present in crude methylamine, based on the principles of the process described on page 6, has been described by A. Mil Her {Bull. Soc. Ghim.y xlii. 202; Journ. Ghem. Soc, xlviii. 501). Dimethylamine. CH C2H7N = CH Dimethylamine occurs in Peruvian guano and pyroligneous acid, and is also present in the products of the distillation of vinasses. Dimethylamine is readily separated from the primary and tertiary methylamines by converting it into ethyl dimethyloxamate (pages 5, 6, 1 4), or into dimethylnitrosamine (page 7). On distilling the first of these derivatives with caustic alkali, or treating the second with fuming hydrochloric acid, the dimethyl- amine is regenerated. The base may also be obtained pure by boiling 35 parts of nitroso-dimethylaniline hydrochloride with a solution of 15 parts of caustic potash in 400 of water: — C6H4(NO).NMe2,HCl + KHO = KCl + C6H,(N0).0H + HNMeg. Dimethylamine boils at 8°-9° C, and closely resembles the primary and tertiary methylamines. From the former it is at once distinguished by the non-formation of a precipitate on the addition of ethyl oxalate to the aqueous solution of the base (page 6), and the non-production of an isonitrile on treatment with alcoholic potash and chloroform. From trimethylamine it is distinguished by the formation of a nitrosamine on treating it with nitrous acid, or one of its salts with a nitrite (page 7). The chloroplatinate, (Me2H2N)2PtCl6, crystallises in very long needles. Trimethylamine. CH3) Trimethylamine, often improperly called propylamine, a base having the constitution (CgH^)!! N, occurs somewhat frequently both in the animal and vegetable kingdom. In the former it occurs notably in herring-brine, and has been detected in urine, unputre- TRIMETHYLAMINE. 13 fied blood of the calf, cod-liver oil, and other animal fluids. In the vegetable kingdom, trimethylamine occurs in the Chenopodium vulvaria (stinking goose-foot), from the leaves of which it con- stantly exudes; Arnica montana; Mercurialis annua; the blossoms of the pear, white- thorn {Gratoegus oxyacantha), hawthorn, and wild cherry ; and in ergot ^ and other parasites of the vegetable kingdom. Trimethylamine is also a product of the dry distillation of certain alkaloids, wood, &c., but especially of the vinasses or residue left after the distillation of the spirit from fermented beet- root molasses. The bases obtained by the destructive distillation of this product are derived from the b e t a i n e, CgHj^NOg, con- tained in the molasses, and consist chiefly of the monamines of methyl, among which trimethylamine predominates.^ The products of the destructive distillation of the " vinasses," left after the distillation of the fermented beetroot-molasses, vary ^7ith the concentration of the liquid. As the proportion of water decreases, the quantity of ammonia increases, and the trimethyl- amine is replaced by the primary and secondary methylamines. The vinasses from different localities yield varying proportions of gaseous and liquid products on distillation, the nitriles and methylic alcohol appearing to be the most variable constituents.* ^ The trimethylamine of ergot is probably a decomposition-product of choline, (CH3)3N(C2H40H).OH. 2 Tlie vinasses, or spent wash from the stills, is evaporated till it acquires a specific gravity of 1"31, when it is subjected to dry distillation in cast-iron retorts. The aqueous portion of the distillate contains : — Ammonium car- bonate, sulphydrate and cyanide; methyl alcohol, methyl sulphide, and methyl cyanide; various other bodies of the fatty series; and a large proportion of salts of trimethylamine. The tar yields, on distillation : — ammoniacal liquor, various oils, pyridine bases, solid hydrocarbons, phenols, and pitch of superior quality. The aqueous liquid is neutralised with sulphuric acid and concen- trated, when crystals of ammonium sulphate are deposited, and vapours of methyl alcohol are evolved together with methyl cyanide and other nitriles. The methyl cyanide is converted in ammonia and acetate by treatment with an alkali :— CH3. NO + NaHO + H2O - H3N + CH3. COONa. The dark-coloured mother-liquors retain the trimethylamine sulphate, which is decomposed by distillation with lime, the vapours being passed into hydrochloric acid. The re- sultant solution is boiled down till the temperature reaches 140° C. Ammonium chloride crystallises out on cooling, and the mother-liquor is separated and concentrated till the boiling-point rises to 200°, the product forming com- mercial hydrochloride of trimethylamine, from which the free base may readily be obtained by treatment with lime or caustic alkali. * In a specimen of "commercial trimethylamine," prepared from vinasses, Duvillier and Buisine found only from 5 to 10 per cent, of trimethyl- amine and some 50 per cent, of dimethylamine ; while the remainder consisted of raethylamine, propylamine, and isobutylamine in about equal proportions ; 14 AMINES FROM VIN ASSES. Trimethylamine has a specific gravity of 0'673 at 0°, and boils between 9° and 10° C. When pure and concentrated, trimethyl- the ethylaniine being estimated at about 2 per cent., and ammonia being absent {Compt. Bend., Ixxxix. 48). The method employed by these chemists for the separation of the amines in question was as follows {Ami, Chim. Phys., [5], xxiii. 289) : — The aqueous solution of the free bases was treated with ethyl oxalate, the dense white precipitate of oxamides filtered off, the filtrate con- centrated by distillation, and the further precipitate added to that previously obtained. By treating the precipitate with hot water it was separated into three fractions. The most insoluble portion (1) consisted of dibutyl- oxamide (or possibly di-tsobutyloxamide), which melted and floated on the hot water, and on cooling formed a solid waxy mass. When recrystal- lised from alcohol, it was obtained in pearly needles. The biUylamine, C4H9NH2, obtained by distilling the oxamide with potash, had a faintly aromatic odour, and yielded a slightly soluble chloroplatinate, crystallising in orange-coloured plates. Of the oxamides soluble in boiling water, thedipropyl compound (2) was first deposited. It crystallised from alcohol in pearly needles melting at 110°, and the propylamine, C3H7.NH2, obtained from it gave an orange chloroplatinate. When the proportion of butylamine and propylamine was small, the authors preferred to utilise the comparative insolu- bility of their sulphates in alcohol to separate them from the other amines. The most soluble portion of the mixed oxamides (3) was deposited in opaque white needles or grains, and consisted of dimethyloxamide. The base obtained by distilling it with potash was converted into the sulphate, which on treatment with boiling absolute alcohol was obtained quite pure, and yielded pure methyl amine on treatment with potash. The mother-liquor separated from the oxamides of the primary amines was distilled with caustic potash, and the dried gas collected in absolute alcohol. A portion of the solution was then titrated with standard acid, and the remainder gradually added to a quantity of ethyl oxalate sufficient for the reaction:— Me2NH + Et2C204 = (MeHN)2C202 + 2EtOH; assuming the alkalinity to be wholly due to dimethylamine. The operation was conducted in a flask, which was surrounded with ice and continually shaken. When the reaction was completed, the flask was heated on the water-bath, and the alcohol and un- changed trimethylamine distilled off and collected in hydrochloric acid. It yielded a chloroplatinate in large orange-red crystals, and was the only tertiary amine found in the mixture of bases under examination. The syrupy residue left in the flask after the distillation of the alcohol and trimethylamine consisted of the ethyl dialkylated-oxamates, with traces of athyl monalkylated-oxamates and oxamides of primary amines. It was treated with water, which caused hydrolysis ; and, on neutralising the liquid with milk of lime, calcium ethyloxamate and propyloxamate were thrown down, which on distillation with potash yielded ethylamine, C2H5.NH2, and propylamine, J3H7.NH2. On treating the filtrate from the calcium oxamates precipitate with an equal volume of alcohol, a precipitate was formed from which warm water extracted calcium dimethyloxamate, yielding dimethylamine, (CH3)2lSrH, on distillation with potash, while the less soluble portion consisted of calcium monomethyloxamate, yielding methylamine under similar treatment. lamine, which escaped detection on Duvillier and Buisine'sfirst TRIMETHYLAMINE. 15 amine is stated to have a purely ammoniacal odour; but when highly diluted, the vapour has at the same time a smell of ammonia and a peculiar fishy odour suggestive of herring-brine. The latter odour is gradually developed by adding lime to a solution of the base, but requires some time to reach its maximum intensity (L. Taylor). Trimethylamine is apparently soluble in all proportions of cold water. ^ A mixture of equal measures of trimethylamine and water is inflammable. Trimethylamine is employed for preparing pure potassium car- bonate from the chloride by a method analogous to the ammonia- soda process. Ammonia is not available, because of the nearly equal solubility in water of amm mium chloride and acid potassium carbonate, whereas the hydrochloride of trimethylamine is much more soluble. Trimethylamine might, primd facie, be supposed the active agent in Wollheim's process of treating sewage with herring-brine and lime {Eng. Patent No. 15321, 1888); but those who have investigated the matter incline to the opinion that the bactericide is a hitherto unisolated body they term a m i n o 1, produced by the action of lime on one of the amines of herring-brine. Pure trimethylamine employed without lime has not the same effect. Trimethylamine is distinguished from the primary and secondary methylamines by its negative reaction with alcoholic potash and chloroform (page 7), ethyl oxalate (page 5), and nitrous acid (page 7), and by its solution in excess of hydrochloric acid being precipitated by potassium ferrocyanide (page 8). Trimethylamine has been employed in medicine, and is said to have proved of value in the treatment of gout and acute rheumatism. examination of the bases from viuasses, owing to the small proportion present, was subsequently detected by distilling with potash the mother-liquors ob- tained by treating the oxamides with water, and converting the bases into sulphates. On treating these with absolute alcohol, the sulphate of methyl- amine remained. On distilling the soluble portion with alkali, collecting the bases in absolute alcohol, and treating the solution with ethyl oxalate, as rdready described, the ethylamine was converted into a monoethyloxamate, from which the calcium salt was prepared and decomposed by alkali. ^ According to Guthrie, the solubility of trimethylamine in water is notably diminished by heating, the liquid becoming distinctly turbid (com- pare nicotine) from partial separation of the base. Thus a 10 per cent, solution of trimethylamine in water became turbid at 22° C. ; an 8 per cent, at 24°*5 ; and a 4 per cent, solution at about 42° C. Leo Taylor has failed to confirm Guthrie's observations, which were not improbably made on impure material. 16 TRIMETHYLAMINE HYDROCHLOKIDE. (A valuable description of its therapeutic effects will be found in the Year -Bonk of Pharmacy for 1873, pages 1 9 7-2 6 2.) i Trimethylamine combines with carbon disulphide at the ordinary temperature with great evolution of heat, according to the equation CS2 + (CH3)3N = N(CH3)2.CS.S.CH3. The product, which may be regarded as trimethyl-thiocarbamic acid, is prepared more readily by passing gaseous trimethylamine into a mixture of carbon disulphide and alcohol. It is obtained on evaporating the solvent in white rhombic needles, melts at 125°, and decomposes gradually at the ordinary temperature. It is soluble in dilute alcohol and water, but nearly insoluble in absolute alcohol, ether, chloroform, or benzene. Dilute acid combine with it to form salts, but strong acids and alkalies decompose it into carbon disulphide and trimethylamine. Trimethylamine Hydrochloride. Hydrochlorate of trimethyl- amine. Chloride of Trimethylammonium. (CH3)3HNC1. This salt is obtained by neutralising trimethylamine with hydrochloric acid. It differs from ammonium chloride in being extremely deliquescent, and soluble in absolute alcohol. The fishy odour of the base liberated on treating the salt with lime or caustic alkali further distinguishes it from ammonium chloride. With platinic chloride it unites to form the chlornplatinate, (MegHXj^PtClg, a com- pound which crystallises in orange octohedra, sparingly soluble in absolute alcohol. When heated to 260°-285° C, trimethylamine hydrochloride is decomposed with formation of free trimethylamine, ammonia, and methyl chloride: — SMeHNCl = 2Me3N + H3N + 3MeCl. This reaction has been utilised by Camille Vincent for the manu- facture of methyl chloride. The vapours are passed through hydro- chloric acid, which absorbs the bases, while the gaseous methyl chloride passes on. It is washed by dilute caustic soda and dried by strong sulphuric acid, after which it is collected in a gas-holder, from whence it is pumped into strong wrought-iron cylinders, in which it is condensed to liquid. The vapour of liquid methyl chloride has a tension of 2*5 atmospheres at 0° and 4'8 at 20° C. 1 The solution of trimethylamine for medicinal use should be clear, colour- less, and of 1'124 specific gravity. It should have a peculiar odour, recalling that of ammonia and herring-brine, be miscible in all proportions with water and alcohol, and contain 20 per cent, of the base. One measure of hydro- chloric acid, of 1'170 specific gravity, should neutralise three measures of the solution of the base, and the salt obtained on evaporating the resultant solu- tion should be completely soluble in absolute alcohol. ETHYLAMINES. 17 Methyl chloride is extensively used in the aniline-dye manufacture for preparing methylaniline and dimethylaniline, which compounds form the starting-points of numerous colouring matters. Ethylamines. The amines of ethyl are obtainable in the manner already described (page 3). A convenient source of the primary amine, C2H5.NH2, is the crude ethyl chloride obtained as a bye-product in the manufacture of chloral (A. W. H f m a n n, Ber., iii. 109, 776). When ethyl chloride is heated to 90° under pressure with an equivalent proportion of strong aqueous ammonia, a layer of triethyl- amine containing ammonia is formed, while the aqueous liquid contains the hydrochlorides of ethylamine and diethylaraine. When a similar mixture of aqueous ammonia and ethyl chloride is heated under pressure to 150° C, H^NCl, EtHgNCl, and Et^NCl are the chief "products, only traces of EtgHgNCl and EtgHNCl being formed. The amines of ethyl can be separated by methods already described. They present the closest analogy to the corresponding methyl bases. Various differences between the three amines are described on page 4 et seq. The following table shows other of their characteristic properties. Ethylamine. DIETHYLAMINE. Triethylamine. Formula. (C2H5)H2N (C2H5)oHN (C2H5)3N BoiUng-point, ° C. 19 56 90 Specific gravity. |0-6964 -0-7062 X ?2o-7277 X |o-708 fo-706 Reaction with zinc sulpliate. Precipitate soluble in excess. Precipitate insoluble in excess. Precipitate in- soluble in excess. Product when boiled with nitrous acid (or a salt of the bases with sodium nitrite solution). Alcohol and nitro- gen. Diethylnitrosamine ; a neutral oily liquid boiUng at 177% and distilling with steam (page 7). Unchanged. Hydrochloride. Deliquescent laminse and prisms. Non-deliquescent plates. Non-deliquescent laminae. Platinichloride. Hexagonal rhom- bohedra ; mode- rately soluble in water. Monoclinic ; mode- rately soluble. Monoclinic; very soluble. Acid ferrocyanide. i Soluble. Soluble. Very sparingly soluble. VOL. III. PART II. 18 TETRA- ALKYLATED AMMONIUMS. AMMONIUM BASES. By the action of excess of an alkyl iodide on ammonia or an amine, all the hydrogen atoms of ammonia can be replaced by alkyl radicals, the tertiary amines thus formed combining with another molecule of alkyl iodide to produce the iodide of a tetra-alkylated ammonium. When methyl iodide has acted on ammonia, the product is tetramethyl-ammonium iodide, (CHg)^]!^!; but by obvious modifications in the process, similar compounds containing other alkyl-radicals can be obtained. Thus, H f m a n n prepared the iodide of methyl-ethyl- amyl-phenyl-ammoni u m:— (CH3)(C2H5)(C5Hii)(C6H5)NI. The same product results from the action of ethyl iodide on trimethylamine as by the action of methyl iodide on dimethyl- ethylamine. This fact proves that the body formed is not merely a molecular compound of the constitution CH3) CH3) CHgU-.C^H,!; or CH3 U.CH3I ; CH3 j C2H5 ) but that it is the true iodide of a tetra-alkylated ammonium : — CH3 The identity of these and similar compounds furnishes important evidence of the pentavalent character of nitrogen. The iodides of the tetra-alkylated ammoniums are quite un- acted on by caustic potash even on heating, but react with recently precipitated argentic oxide to form iodide of silver and the hydroxides of the tetra-alkylated ammoniums. These hydroxides are non-volatile, syrupy or solid deliquescent substances, of highly caustic, alkaline character, presenting, as a class, a strong analogy to caustic potash. Many of them have marked poisonous characters. Such of the natural vegetable alkaloids as have the constitution of tertiary bases unite with alkyl iodides to form compounds which have the characters of iodides of compound ammoniums, from which the corresponding hydroxides can be prepared, as above described, by reaction with oxide of silver. Thus, for example, from morphine, Ci^HigNOg, may be prepared : — Ethylmorphium iodide, .... CjyHjgOg \^j Ethylmorphium hydroxide, . . C17H19O3 ] ^ ^.-rr COMPOUND AMMONIUM BASES. 19 These bodies are sometimes formulated and described as the hydriodide and hydrate of ethylmorphine, Ci7Hi8(C2H5)N03 ; but such a view is inconsistent with their characters. Similar bodies are obtained by action of alkyl iodides on strychnine. The hydroxides of methyl- and ethyl-strychnium (C2iH.^2MeN02.0H and C2iH22EtN02.0H) are strong, very soluble bases, which form carbonates and precipitate metallic hydroxides from metallic solutions. In their physiological action they simulate the paralysing action of curarine rather than the tetanic poisoning of strychnine itself. Similar bases can be obtained by the action of alkyl salts on diamines or ammonia. Thus, an end-product of the action of excess of ethylene dibromide on ammonia is tetra-ethylene- di-ammonium-dibromide (C2H4)4N2Br2, from which the hydroxide, (C2H4)4N2.0H, can be obtained by treatment with oxide of silver. This base is a powerful caustic alkali and non- volatile. Choline and neurine, described in the chapter on "Animal Base s," are natural products having the constitution of am- monium bases. Thus : — Choline. Trimethyl-hydroxyethyl- ) . . (CH3)3 1 -j^ ^^t ammonium hydroxide, j . . (C2H4.OH) J Neurine. Trimethyl-vinyl-ammonium "j . . (CH3)3 ) ^ ^^ hydroxide, J. . (C2H3)|^^-^^ It will be observed that neurine and choline only differ from each other by the elements of water. Bases of similar characters and constitution have been prepared, containing phosphorus, arsenic, or antimony in place of nitrogen. Thus, there have been obtained : — Tetramethyl-ammonium hydroxide, . . Me^N.OH Trimethyl-ethyl-phosphonium hydroxide, . MegEtP.OH Tetrethyl-arsonium hydroxide, . . Et^As.GH Tetrethyl-stibonium hydroxide, , . Et^Sb.OH Tetrethyl-ammonium Compounds. When perfectly anhydrous ethyl iodide is added to trimethyl- amine previously dried over caustic potash, combination gradually occurs with evolution of heat, and in a few days the mixture sets to a solid mass of Tetrethylammonium Iodide^ (C2H5)^NI. This compound is pre- ferably prepared by exposing a mixture of equivalent proportions of triethylamine and ethyl iodide to a temperature of 100° for a 20 TETRETHYLAMMONIUM COMPOUNDS. few minutes in a flask furnished with a well-cooled inverted con- denser, or preferably in a sealed tube. Violent reaction ensues, and, on cooling, the product sets to a hard mass of crystals. On dissolving the mass in water, and allowing the solution to evapo- rate spontaneously, the iodide is obtained in extremely bitter crys- tals of considerable size, which, when pure, are colourless, but are apt to be mixed with reddish crystals of the tri-iodide, (CA)4NI,l2.' Tetrethylammonium iodide is not volatile at 100° C, but when rapidly heated in a retort to a higher temperature it melts and sufi'ers decomposition into ethyl iodide and tri m ethyl- am i n e, which form separate layers in the receiver but re-unite to produce the original compound. Tetrethylammonium iodide is wholly undecomposed by treat- ment with caustic potash or soda, but is much less soluble in caustic alkaline solutions than in water. Hence, on adding excess of caustic potash to its concentrated aqueous solution, a solid crys- talline mass is produced. This behaviour sharply distinguishes the iodide of tetrethyl-ammonium (and of other compound ammo- niums) from the compounds EtgHNI, EtgHNI, and EtH^NI, which are at once decomposed by caustic alkali, with liberation of the corresponding amine. The aqueous solution of tetrethylammonium iodide reacts with argentic nitrate or sulphate to form a precipitate of argentic iodide and a solution of the tetrethylammonium nitrate or sulphate. Tetrethylammonium Hydroxide, (C2H5)4N.0H, is obtained in solution by adding freshly-precipitated oxide of silver to a dilute and warm solution of tetrethylammonium iodide, until the brown colour of the silver oxide ceases to change into the lemon-yellow of the iodide. The solution is then filtered, and may be evaporated to a considerable extent at a gentle heat, but further concentration must be conducted in vacuo, at the ordinary temperature, over sul- phuric acid and lime. Long, hair-like, deliquescent needles of the base are deposited, but these subsequently disappear, and the liquid ultimately dries up to a semi-solid mass. Tetrethylammonium hydroxide presents the closest analogy to caustic potash. It is highly deliquescent, absorbs carbon dioxide from the air, and the aqueous solution has a strong alkaline re- action. It has an alkaline, caustic, and extremely bitter taste, and in a concentrated state burns the tongue and acts on the skin like caustic potash. With metallic solutions it behaves like the caustic alkalies, except that aluminium hydroxide is soluble with 1 This compound is readily obtained by dissolving iodine in a solution of tetrethylammonium iodide. TETRETHYL AMMONIUM COMPOUNDS. 21 difficulty in excess of the reagent, and chromic hydroxide is quite insoluble. A moderately strong solution of tetrethylammonium hydroxide may be boiled without decomposition ; but in a concentrated state, even at 100°, the liquid froths strongly, and the base is resolved gradually but completely into triethylamine, ethylene, and water :— (C2H5)N.OH = (C2H6)3N + CgH^ + H.OH.i This reaction affords a convenient means of obtaining triethylamine unmixed with the primary and secondary amines. When a solution of tetrethylammonium hydroxide is boiled with a slight excess of ethyl iodide for twenty-four hours, under a reflux condenser, the solution becomes perfectly neutral, the following reac- tion occurring :_(C2H5)4N.OH + C^R.l = (CgH^^NI -f CgH^.OH. Tetrethylammonium hydroxide also hydrolyses ethyl oxalate and saponifies fats as readily as caustic potash. On adding caustic potash and potassium iodide to a strong solu- tion of tetrethylammonium hydroxide, a white crystalline mass of tetrethylammonium iodide is produced. The salts of tetrethylammonium are mostly crystallisable and readily soluble. Tetrethylammonium Chl&nde, (C2Hg)4NCl, obtained by neutralis- ing the hydroxide with hydrochloric acid, is crystalline and highly deliquescent. It forms double salts with auric, mercuric, and platinic chlorides. Tetrethylammonium chloroplatinate, (Et4N)2PtClQ, is thrown down immediately as an orange-yellow precipitate, con- sisting of microscopic octahedra, on adding platinic chloride to a solution of tetrethylammonium chloride. It is slightly soluble in water, and less soluble in alcohol and ether. ^ Collie and Schryver {Jour. Chem. Soc, Ivii. 767) have recently shown that when a mixed quaternary-ammonium chloride or hydroxide (made from trimethylamiue or triethylamine) is heated, amixedtertiaryamine is always produced in greater or less amount. With triphenylmethylammo- nium the only product is dimetliylplienylamine, while with the allyl- and isopropyl-trimethylammonium compounds, the chief tertiary amine formed by the action of heat is trimethylamiue In the case of the chlorides, the methyl-group is very easily eliminated as methyl chloride; whilst in the case of the hydroxides, the ethyl-group almost invariably splits away as ethylene. (See a later paper by S e li r y v e r on the asymmetry of nitrogen in substituted ammonium compounds. Froc. Chem, Soc., 1891, page 39.) HYDRAZINES. The name hydrazine M'as first applied by E. Fischer to a hypothetical base, having the constitution of diamidogen, HgN.NHg. Since then the base itself has been obtained in the form of a hydrate, and possibly also in the free state. Hydrazine. Diamidogen. Diamide. IS'gH^ or H2N.NH2. Hydrazine is obtained by the decomposition of triazo-acetic acid by heating it with water or mineral acids, when the following reaction occurs : — C3H3Ng(COOH)3 + 6H2O = 3N2H4 + SC^H^O^. Triazo-acetic acid. Water. Hydrazine. Oxalic acid. The oxalic acid is more or less split up, according to the temperature and the strength of the acid employed, into carbonic and formic acids, so that when only water is used the hydrazine separates as a formate; but if a mineral acid be present it forms the corresponding salt. Hydrazine has an extraordinary affinity for water, readily forming a hydrate, ^2^i>^2^> which it does also when set free from its salts by caustic alkalies or lime.^ This hydrate is a liquid fuming in the air and boiling unaltered at 119° C, and can be easily separated from water by distillation, though some of it passes over with the steam. When heated with barium oxide in a sealed tube to 170°, some anhydrous hydrazine appears to be formed and escapes as a white fume on opening the tube. The solution of hydrazine turns reddened litmus-paper a deep blue, and gives white fumes with acid vapours. In a concentrated state it has a very peculiar odour, only slightly resembling that of •^Hydrazine hydrate is best prepared (Cur tins and Schultz) by dis- tilling a mixture of eleven parts of hydrazine sulphate with four of caustic potash and one of water in a silver retort provided with a silver condenser. When the last drop has passed over, the distillate is fractionated. After four fractionations the last portions boil constantly at 119°. Curtius and Jay {Jour. Pract. Chem., [2], xxxix. 27) prepare hydrazine hydrate by heating the hydrochloride of the base with caustic lime in a silver retort, and passing the vapours through a heated silver tube containing caustic lime. SALTS OF HYDRAZINE. 23 ammonia. It powerfully affects the nose and throat, has an alkaline taste, and leaves a burning sensation on the tongue. When boiling, the solution attacks glass, and quickly destroys corks and india-rubber. Hydrazine, like hydroxylamine, is a strong poison of universal character. Hydrazine reduces Fehling's solution and ammonio-nitrate of silver in the cold. With cupric sulphate it yields a red precipitate (? cuprous oxide), with mercuric chloride a white precipitate, and precipitates alumina from a solution of alum. With aromatic alde- hydes and ketones it yields sparingly soluble crystalline compounds. Salts of Hydrazine. Hydrazine combines with one or two molecules of monobasic acids to form very stable salts, which are usually crystalline and isomorphous with the corresponding ammonium salts. The salts Hz,2HR crystallise in the regular system and are readily soluble in water, but nearly insoluble in alcohol. The mono-acid salts, HzHR, are easily soluble in water and warm alcohol, from which they crystallise well. The salts of both classes are insoluble in ether, benzene, &c. In acid solution, the salts of hydrazine possess remarkably strong reducing properties, and are powerfully toxic towards the lower organisms. Peptone solutions containing 0*1 per cent, of hydrazine sulphate are unable to support bacterial life. Hydrazine Diliydrochloride, '^^^,^HC\, crystallises from hot water in large glassy octahedra that are freely soluble in water, but less so in alcohol. On treatment with platinic chloride it does not yield a chloroplatinate, but is decomposed with evolution of much nitrogen. It melts at 198° C, with evolution of hydrochloric acid, to a clear glass consisting of the monohydro- chloride, KgH^jHCl, and this on further heating to 240° C. is decomposed into ammonium chloride, nitrogen, and hydrogen. Hydrazine Sulphate, l^^^^^^^i^ according to T. Curtius, is best obtained from ethyl diazo-acetate, which on treatment with hot concentrated caustic potash yields the ])otassium salt of an acid which separates in golden yellow tablets on addition of a mineral acid. On digesting the yellow aqueous solution of these with very dilute sulphuric acid, the colour disappears without evolution of gas, and on cooling crystals of the sparingly soluble hydrazine sulphate are obtained. From the sulphate, other salts of hydrazine may be prepared by double decomposition with barium salts. Salts of hydrazine in solution are decomposed by sodium nitrite, with evolution of gas attended by much frothing. The reaction is analogous to the decomposition of ammonia salts by a nitrite, with the difference that whereas in the latter case (a) nitrogen is 24 AZOIMIDE. IMIDAZOXC ACID. formed, in the case of hydrazine (6) a z o i m i d e, HNg, is found among the products of the reaction : — (a) :NH3,HC1 +NaN02 = :N^aCl + 2H20 + N2. (b) NgH^^Cl + KaNOg = NaCl + 2H,0 + H^^3. AzoiMiDE. Imidazoic Acid. HNo = HN<:'.. The above reaction is not a suitable one for the preparation of this remarkable body, which, according to its discoverer, T. Curtius (Ber., xxiii. 3023), is best obtained by decomposing nitroso-hippurylhydrazine, NHBz.CH2.CO.N(:N^O).NH2, with dilute soda, which splits it up into hippuric acid and the sodium salt of azoimide : — NHBz.CH2.CO.N(i^O).NH2 + 2KaH0 = NHBz.CH2.C00Na + 2H20 + NaN3. On distilling the compound NaNg with dilute sulphuric acid, imidazoic acid volatilises with the steam, which when passed into a neutral solution of nitrate of silver gives a precipitate of the silver salt. This is washed and decomposed by dilute sulphuric acid, the solution being used instead of silver nitrate to absorb the vapours of imidazoic acid. By repeating this process, a solution containing 27 per cent, of the new acid is obtainable. In the anhydrous state, imidazoic acid is a colourless gas of a peculiarly nauseous odour, and condensible on cooling to an extremely explosive liquid. It is very soluble in water, and on distillation of the liquid a concentrated acid passes over, the distillate gradually becoming weaker until an acid of constant composition and boiling-point distils. The solution reddens litmus, and gives white fumes with ammonia, of the salt NH3.HN3 or N4H4, which sublimes completely at 100° 0., but does not crystallise in the cubic system like ammonium chloride. Iron, zinc, copper, aluminium and magnesium dissolve readily in dilute imidazoic acid (7 per cent.) with evolution of hydrogen, and gold is dissolved with formation of a red salt. The silver (AgNg) and mercurous salts of imidazoic acid are insoluble, the former closely resembling silver chloride, but not blackening in the light. Both the silver and the mercurous salts are extraordinarily explosive, 0*001 gramme of the former indenting an iron plate on which it is heated to 250°. Barium iinidazoate, BaNg, separates from concentrated solutions in short shining anhydrous crystals, which explode with a green flash when heated, or exposed to a strong green light. The solution of cupric imidazoate deposits cuprous oxide on boiling. The free acid is SUBSTITUTED HYDRAZINES. 25 liberated from any of the imidoazoates on treatment with dilute sulphuric acid. With concentrated sulphuric acid, the azoimide is itself decomposed. Etlters of imidazole acid have been prepared, phenyl imidazoate, PhNg, being identical with the diazobenzolimide previously described by G r i e s s.^ SUBSTITUTED HYDRAZINES. Hydrazine is the parent of a large and important class of bases generally called hydrazines, one member of which, phenyl- hydrazine, (CgHg)H]S'.NH2, has proved, in the hands of E. Fischer and others, a reagent of the highest importance, numerous recent syntheses in the sugar group having been effected through its aid. By replacing a second atom of hydrogen by {e.g.) phenyl, secondary hydrazines may be obtained either symmetrical like hydrazobenzene, (CgHg)HN.NH(CgH5), or unsymmetrical like diphenylhydrazine, (CeHg)2N.NH2. The latter class resemble the tertiary amines (pnge 18) in their power of reacting with the haloid salts of the alkyl radicals (e.g.y ethyl-iodide) to form hydrazonium compounds : — R2N.NH2 4- AkI = IAkR2N.NH2. The hydrazines containing fatty alkyl radicals are liquids boil- ing without decomposition ; those of the aromatic series are readily fusible solids or oily liquids, and are partially decomposed on dis- tillation. Hydrazine itself and some of the fatty derivatives are di-acid bases ; but the hydrazines of the benzene series have all monobasic functions. The hydrazines closely resemble the amines, but are dis- 1 From the ascertained characters of imidazoic acid, and its analogy to hydrocyanic acid, Mendelejeff has forniulated some very interesting prog- nostications. Just as ammonium formate, when heated, yields formamide and the nitrile HON, so ammonium nitrate decomposes on heating with production of (an intermediate hypothetical nitramide and) the nitrile N2O, nitrous oxide. Similarly, azoimide may be regarded as the nitrile of diammonium ortho- nitrate, thus : — Formate, . .HCO.O.NH4 - 2H2O-H C.N ; hydrocyanic acid. Meta-nitrate, . O.NO.O.NH4 -2H20 = NO.N; nitrous oxide. Ortho-nitrate, . HO.NO:(O.NH4)2-4H20=.HN.N2 ; imidazoic acid. It seems not improbable that the ammonium salt of imidazoic acid, NH3.HN3, may prove convertible into its symmetrical isomeride, N.NH2.NH2.N, the nitrile of triammonium orthonitrate, NO(ONH4)(ONH4)(ONH4), just as ammonium cyanate can be changed into urea. The existence oi explosive, coloured, double imidazoates is foretold by Mendelejeff. 26 ETHYL-HYDRAZINE. tinguished from the latter by their capacity of reducing Fehling's copper solution, in many instances at the ordinary temperature. The product of the oxidation of the hydrazine is the corresponding amine. Thus, diethyl-hydrazine, (C2H5).2N.NH2, is oxidised to diethyl-amine, (02^.^)2^^' The general and special characters of the hydrazines are sufficiently exemplified by two typical species, ethyl- hydrazine and phenyl-hydrazine. Ethyl-hydrazine. CgHgN^ = (C2H5)HN.NH2 . On treating diethyl-urea with nitrous acid, a n i t r s 0- compound is formed, which on reduction with zinc-dust and acetic acid is converted into a body called diethyl-semicar- b a z i d e. „ fNH(CA) fNH(C,H,) |NH(C,H,) ^"1NH(C,H,) ^^ 1 N(NO)(C,H,) ^" j N(NH,)(C,H,) Diethyl-urea. Nitroso-compound. Diethyl-semicarbazide. This last body decomposes, on heating with strong hydrochloric acid, into ethyl-hydrazine, ethylamine, and carbon dioxide : — NH(C2H5).CO.N(NH2)C2H,-hH20 = HK(NH2)(C2H5) + HNH(C2H5) + C02. The ethylhydrazine hydrochloride is less soluble than the cor- responding salt of ethylamine, and may be separated from it b^ crystallisation. Ethylhydrazine is a colourless, mobile liquid of ethereal and faintly ammoniacal odour. It boils at 100°, and distils undecom- posed. It is very hygroscopic, forming white fumes with moist air, dissolves in water and alcohol with evolution of heat, and corrodes cork and caoutchouc. Ethylhydrazine gives Hofmann's isonitrile reaction for primary amines with chloroform and alcoholic potash (page 7). Bromine decomposes it with evolution of nitrogen, and it is also decom- posed by nitrogen trioxide. Ethylhydrazine is a very powerful deoxidising agent. It reduces Fehling's copper solution at the ordinary temperature, reduces argentic oxide, and converts oxide of mercury into mercuric e t h i d e, Hg(C2lIg)2. It yields a black precipitate with Nessler's solution. Ethylhydrazine reacts with aldehydes, with evolution of heat, to form ethyl-hydrazides, R.CH:K'2H(C2H5). DiEtHVLHYDRAZINE. 27': Potassium anhydrosulphite, KgSgOy, reacts on ethylhydrazine to form potassium ethyl-hydrazine sulphite, (C2H5)HN.NH(S03K), which, on treatment with mercuric oxide, gives potassium diazo-ethane-sulphonate, C2H5.N: ^".(SOgK), a substance which explodes violently when warmed, and otherwise resembles the diazo-benzene-sulphonates (Part I. page 137). Diethyl-hydrazine, (C2H5)2N.NH2, is obtained by the reduction of the nitroso-derivative of diethylamine : — (02115)2^.^0 + 2H2 = (02H5)2N.NH2-|-H20. It boils at 98°, and closely resembles ethylhydrazine, but does not reduce Fehling's solution unless the liquid is heated. It unites with ethyl iodide to form the body (02115)3X21121, which on treatment with oxide of silver yields a strongly alkaline solution oftriethylazonium hydroxide, (02115)3^2112 OH, a powerful base analogous to tetrethylammonium hydroxide (page 20), and which, when heated with water, decom- poses into ethylene, diethyl- hydrazine, and water. Mercuric oxide, even in the cold, converts diethyl-hydrazine into tetraethyl- tetrazone, (02H5)2N.]S' : N.N(02H5)2, a colourless, strongly basic oil, volatile with steam and yielding a metallic mirror with ammonio-nitrate of silver. Phenyl-hydrazine. C6H8N2==(06H5)HKNH2. Phenyihydrazine is prepared by the action of reducing agents on diazobenzene compounds, OgHgN : NX (Part I. page 176). Thus diazobenzene chloride may be reduced by the calculated amount of stannous chloride and hydrochloric acid ; or the potassio- sulphite with zinc-dust and acetic acid, the product being subse- quently decomposed by boiling with hydrochloric acid : — C6H5.HKNH.SO3K + HCl + HgO = KHSO4 4- 06H5.HKNH2,H01.i • Phenyihydrazine is a yellow oil of a faint aromatic odour. It solidifies at low temperatures to a crystalline mass, melts at 23°, and boils, with slight change and evolution of ammonia, at 241°-242°. ^ Phenyihydrazine is best obtained, as described by V. M e y e r, by dissolving 1000 parts of aniline in 2000 parts of strong hydrochloric acid, cooling the solution by means of ice, and then slowly adding an ice-cold solution of 75 parts of sodium nitrite in 400 c.c. of water. To the cold solution of diazo- benzene chloride, CgHg. N : N. CI, so obtained, a solution of 450 parts of stannous chloride in an equal weight of hydrochloric acid is then added. The mixture soon sets to a white cr3'stalline pulp of phenyihydrazine hydrochloride, CfiHoNHajHCl, which is filtered or strained off, and washed with a mixture of alcohol and ether. The free base is obtained by dissolving the hydrochloride in water, adding caustic soda, and agitating with ether, which is separated and evaporated. The product may be purified by distillation. 28 PHENYLHYDRAZINE. It volatilises in a current of steam, but not very readily. Phenyl - hydrazine dissolves sparingly in cold water, more readily in hot, and very readily in alcohol, ether, chloroform, and benzene. Phenylhydrazine is readily oxidisable, and becomes red and ulti- mately dark brown on exposure to air, from absorption of oxygen. Phenylhydrazine has well-marked antiseptic properties, and a O'l per cent, solution of the hydrochloride has been recommended as a substitute for one of mercuric chloride of equal strength {Pharm. Jour., [3], xix. 608). Under certain undetermined conditions, contact of phenylhydra- zine with the skin produces troublesome sores. Phenylhydrazine has well-marked basic properties, and forms well-crystallised salts. The hydrocJiloride, prepared as already described, crystallises from hot water in small, thin, lustrous plates, and is almost completely precipitated from its aqueous solution by concentrated hydrochloric acid, a reaction by which phenylhydrazine may be readily separated from aniline and several other bases. Solutions of the hydrochloride and other salts of phenylhydrazine act as powerful reducing agents. They reduce the salts of silver, mercury, gold, and platinum in the cold. Fre&hly-precipitated mercuric oxide is reduced, a salt of diazobenzene being reproduced. Fehling's solution is reduced in the cold, with evolution of nitrogen and precipitation of cuprous oxide, aniline and benzene being simultaneously formed. If phenylhydrazine hydrochloride be treated with a cold solution of potassium nitrite, a nitroso-compound, CgH5(NO)N.NH2 , separates in yellow flocks, which, on treatment with phenol and strong sulphuric acid, yield a brown solution, changing to green and blue. This reaction, observed by Liebermann, is common to all nitroso-derivatives. Phenylhydrazine combines directly with carbon dioxide, carbon disulphide, and cyanogen. The sul phonic acid (para) is em- ployed for the preparation of tartrazin (Part II. page 288) and otlier dyes. Phenylhydrazides. The acetyl-derivative of phenylhydrazine, Cgll5.H^^.NH(C2H30), which may be regarded as acet-phenyl- hydrazide, has powerful antipyretic properties, and has been introduced into German pharmacy under the name of " hydracetin." The same substance is said to be the active ingredient of the preparation known as "p y r o d i n e" {Pltarm. Journ., [3], xix. 425, 508, 1049). Both substances seem to be uncertain in their action and dangerous in use ; in fact, hydracetin is reported by R e n v e r s to be a direct blood-poison, the antithermic properties of which are really due to destruction of the red cori)Uscles. PHENYLHYDRAZIDES. 29 " Orthine" is the name given by R Robert to a body having the constitution of an orthohydrazine-para hydroxy- benzoic acid : — r (OH)(i) i(CO.OH>'^). The free base is very unstable ; but the hydrochloride is stable, reduces the persalts of the heavy metals, and possesses a marked antiseptic action. Phenylhydrazine in aqueous solution reacts very readily with the hydroxy-acids of the sugar group (e.g., gluconic and galac- tonic acids, C5Hg(OH)5.COOH; arabinose-carboxylic acid, CgHj207) with elimination of water, to form crystalline phenylhydrazides, K C0.HN.NH(CgH5). They are prepared by treating a 10 per cent, solution of the acid or its lactone with a moderate excess of phenyl- hydrazine and an equal quantity of 50 per cent, acetic acid, and heating the mixture to 100° for 80 to 120 minutes. The hydrazide sometimes crystallises from the hot solution, but more usually separates on cooling. Any free mineral acid should be neutralised by soda before adding the hydrazine, and bromides, chlorides, and sulphates should be got rid of by adding acetate of lead. If sugar be present, the osazone formed can usually be separated from the hydrazide by crystallisation from hot water. The products are beautifully crystalline, those derived from monobasic acids being but little soluble in cold, and only with difficulty soluble in hot water, while those from polybasic acids (e.g., saccharic, metasaccharic, and mucic) are still less readily soluble. The compounds from isomeric acids usually present a close resemblance in their physical properties, but the acids from which they are derived can be regenerated (in a pure state) by boiling the hydrazide for half an hour with thirty volumes of 10 per cent, baryta water, which treat- ment hydrolyses them completely. From the product, the phenyl- hydrazine is extracted by agitation with ether, and the aqueous liquid, with any precipitate which may have been formed, is boiled and treated with sulphuric acid in quantity sufficient to precipitate the barium as BaSO^. The filtered liquid yields the free acid or lactone on evaporation (Fischer and Passmore, Ber., xxii. 2728; Jour. Chem. >Soc., Iviii. 152). The hydrazides are colourless and readily hydrolysed by 'alkalies and baryta. They can be readily distinguished from the hydra- zones by the reddish violet coloration they give when dissolved in strong sulphuric acid and treated with a drop of ferric chloride solution. 30 PHENYLHYDRAZINE DERIVATIVES. Hydrazones. Phenylhydraziiie behaves in a highly interesting manner with bodies having the constitution of aldehydes and ketones, with whicl. it reacts with elimination of water to form compounds called hydrazones. Most of the bodies of this class are solid and crystalline, and therefore well suited for the recognition of the aldehydes or ketones producing them. The reaction appears to be general for bodies containing the carbonyl group, CO. The reaction is sometimes complicated by the presence of other reactive groups. Thus compounds containing the a-ke tone- alcohol grou p, — CH(OH).CO — , react in the cold with only one molecule of phenylhydrazine to form colourless compounds containing the group:— CH(OH).C.(N.NHC6H5)—. OsAZONES. When the compound thus formed is heated with excess of phenylhydrazine, the alcohol group undergoes dehydro- genisation, reacting at the same time with a second molecule of phenylhydrazine and giving rise to a yellow compound containing the complex group,— C(N.NHC6H5).C(N.NHC6H5)—. Compounds of this kind, in which two hydrazine-residues are attached to two contiguous carbon-atoms, are called osazones, and maybe obtained directly by the action of phenylhydrazine on the di-ketones. They are of interest in connection with the carbohydrates, which may frequently be recognised by means of their characteristic osazones (E. Fischer, Ber.^ xvii. 579; xx. 821). VonJaksch {Jour. Chem. Soc, 1. 744) recommends a solution of phenylhydrazine hydro- chloride containing sodium acetate for the detection of sugar in urine. Pyrazolines. An unsaturated hydrocarbon group {e.g., a 1 1 y 1, CgHg), if contiguous to the carbonyl group, may also react with phenylhydrazine : — -^ -j^ ^ g CH2:CH.COH-hC6H5.HKNH2 = H20-f- |1 | ^ '^ Acrolein. Phenylhydrazine. Water. CH.CH .CH Phenyl-pjTazoline. Pyrazolones. The pyrazolones are derivatives of a body of the formula C3H4N2O , the synthesis of which has been effected by Balbiano {Ber., xxiii. 1103). The relationship of pyrazolone to pyrazol, pyrazoline, and pyrazine is shown by the following formulae : — Pyrazol. Pyrazoline. Pyrazolone. Pprazine.i ^ This body must not be confounded with p i a z i n e, which was formerly called pyrazine, and probably has the constitution : — /CH:CH\ ^CH:CH^ (See A. T. Mason, Jour. Chem. Soc, Iv. 97.) PYRAZOLONES. 81 Phenyl-pyrazolone, CgHg.CgHgNgO, is obtained by heating phenylhydrazine and iodopropionic acid together to 100°, and treat- ing the product, in chloroform solution, with mercuric oxide. Phenyl-methylpyrazolone, CioHjQNgO ; CHg.C — CH2 When phenylhydrazine is added to ethylic aceto-acetate, CH3.CO.CH2.CO.O(C2H5), the two bodies react in the cold, with elimination of water, to form CH3.C(N.NHPh)CH2.CO.O(C2H5) } On heating, the hydrazone thus formed splits up into alcohol and phenyl-methylpyrazolone, a body which was originally regarded by its discoverer, Knorr, as a m e thy 1-oxy quin izine. To prepare phenyl-methylpyrazolone, 100 parts of phenyl-hydra- zine are added to 125 of ethyl aceto-acetate, the water which forms is separated, and the oily product is heated for two hours on a water-bath, until a portion is found to solidify on cooling, or on the addition of ether. The warm mass is poured into and stirred with ether, which removes colouring matter, and the white crystal- line product washed with ether, and dried at 100°. The yield is quantitative and the product pure. It is almost insoluble in cold water, ether, and petroleum spirit, more readily in hot water, and easily in alcohol. It crystallises from hot water or alcohol in hard brilliant prisms.^ The hydrochloride, Cj^qK^qN2^)^^^'^^2^' melts ^ Antithermin. When an aqueous solution of levulinic acid (aceto-pro- pionic acid), CH3.CO.CH2.CH2.COOH, is added to an equivalent amount of phenylhydrazine, dissolved in dilute acetic acid, a yellow precipitate is produced of the h y d r a z n e, CHgCCN. NHPh). CHo. CHg. COOH . When recrystallised from alcohol, this body forms large colourless, odourless crystals of a slight bitter taste, melting at 98°-99"', and nearly insoluble in water, but soluble in alcohol, ether, and dilute acid. It has met with a limited application as an antipyretic under the name of antithermin. It is decomposed by alkalies with liberation of phenylhydrazine, to which fact it probably owes its physiological activity. ^ When a mixture of phenylmethyl-pyrazolone and phenylhydrazine is heated to boiling, disphenyl-methylpyrazolone, C2oH]8N^402, is formed. Heated with methyl alcohol or methyl iodide it yields dianti- p y r i n e, C22H 22^402* melting at 245°, and distinguished from antipyrine by its sparing solubility in water and the melting-point of its picrate (161"). When the body C20H18N4O2 is treated in alkaline solution with excess of sodium nitrite, and the mixture poured into dilute sulphuric acid, pyrazol-blue, C2oHjg'N'402, separates in flocks. When crystallised from chloroform it forms blue needles, insoluble iu water, dilute acids, and alkalies, and only sparingly soluble in alcohol and ether. Its solutions in chloroform and strong sulphuric 32 PHENYL-DIMETHYLPYRAZOLONE. at 96°, ai)d the cMoropIatinate, (CioHioN^O)2H2PtCl6 + 4H20, in prisms melting at 110°. Phenyl-methylpyrazolone yields crystal- line precipitates with salts of many of the heavy metals. With silver nitrate an aqueous solution gives crystals of CioHgAgN20 + ^10^10^2^' "^^^ ultramarine cobalt compound and the orange- yellow uranium salt are especially characteristic. Phenyl-dimethylpyrazolonb. Antipyrine. Phenazonb. C11H12N2O = C3N2H(C6H5)(CH3)20 [Ph : Me : Me = 1 : 2 : 3] ; 1 or, 00.^ NPh.NMe f ' ""'' ^6^5-^ • ^ CO CH :l\ When phenyl-methylpyrazolone is heated with methyl iodide, a further substitution takes place, with formation of phenyl-dimethyl- pyrazolone, a substance known generally as " a n t i p y r i n e," less commonly as "analgesi n," and called in the additions to the British Pharmacopoeia (1890), phenazorie. It is official in the German Pharmacopoeia of 1890 under the name of Antipyrinum. Antipyrine is prepared by heating equal parts of phenyl-methyl- pyrazolone, methyl iodide, and methyl alcohol to 100° in a closed vessel. The dark product is decolorised by boiling with sulphurous acid, the alcohol distilled off, and the residue shaken with strong soda, when the base separates as a heavy oil. This is separated and treated with ether, in which it is sparingly soluble. On separating the ether and evaporating off the solvent, the antipyrine is obtained as a mass of crystals which are purified by recrystallisa- tion from toluene. Antipyrine forms small, lustrous, rhombic needles or plates, which are odourless, but have a somewhat bitter taste. When perfectly anhydrous it melts at 110° to 112° {B.P., 110°; G.P., 113°), but on exposure to air takes up a small proportion (0'6 per cent.) of water, and in that state melts at 105°-107° C. The hygroscopic water may be driven off by exposing the substance to a temperature of 100°, when the original melting-point is restored. Antipyrine is soluble in about its own weight of cold water, and in less than half its weight of boiling water. It dissolves in twice acid has an indigo-blue colour, and gives an absorption-spectrum resembling that of indigo. It is not a substantive dye, is decomposed by strong alkalies, decolorised by chlorine and nitric acid, and converted into disphenyl-methyl- pyrazolone by reducing agents. 1 Two isomers of antipyrine have been prepared, and others are capable of existing. The known isomers differ from antipyrine by being less soluble in water, not yielding nitroso-derivatives, and by giving methyl-aniline either when distilled with zinc-dust or heated with hydrochloiic acid to 200° undei pressure. ANTIPYKINE. 33 its weight of absolute alcohol, but in little more than its own weight of rectified spirit, Antipyrine is soluble in an equal weight of amylic alcohol, and in one and a half times its weight of chloro- form, but requires about fifty parts of ether for solution, is difficultly soluble in benzene, and nearly insoluble in petroleum spirit. On adding strong caustic soda to an aqueous solution of anti- pyrine, the base separates as a milky precipitate, which speedily collects into oily globules. On adding a little ether, these imme- diately solidify to white crystals without appreciably dissolving, but they dissolve instantly on adding chloroform ( J. C. W a t e r h o u s e). An aqueous solution of antipyrine exhibits no alkaline reaction with litmus or phenol-phthalein, but destroys the red colour of an acidulated solution of methyl-orange. Free antipyrine may be determined with accuracy by titration in aqueous or alcoholic solu- tion with methyl-orange. Antipyrine is a strong monovalent base. Its salts, most of which are soluble, do not readily crystallise, with the exception of the picrate (melting at 188°); the ferrocyanide {C-^-Jl-^^jd\^ H^Cfy, which forms a crystalline precipitate ; the chloroplatinate, (CjiHj2N2^)2»^2-P^^^6 + 2-'^2^' which forms yellowish-red prisms melting at about 200° ; and the salicylate (page 37). When antipyrine is heated with hydrochloric acid under pressure to 200°, it suffers complete decomposition, yielding much aniline and a small quantity of methylamine, besides other products. On distillation with zinc-dust it yields benzene, aniline, a base boiling at 86°-87°, and other products. Antipyrine is unchanged by treatment with reducing agents in the wet way, but with oxidising agents it gives a series of interest- ing reactions (Gay and Fortun^, Pharm. Jour., [3], xviii. 1066). Thus when boiled with potassium chlorate and hydro- chloric acid, antipyrine gives a reddish-yellow liquid, which on cooling deposits bright-red oily globules, taken up by chloroform with greenish-yellow colour. A solution of bleaching powder pro- duces no change in the cold, but on heating a brick-red precipitate is formed, and the liquid is coloured yellow. Sodium hypochlorite is said to give the yellow coloration on heating, without any pre- cipitate being formed. Chlorine-water produces no change, and bromine-water a light yellow precipitate, dissolving on heating. Potassium bichromate and permanganate are reduced by acid solu- tions of antipyrine. When a solution of iodine in iodide of potassium is added to a solution of antipyrine, a precipitate is formed which disappears on agitation, leaving the solution colourless ; but on further addition of VOL. III. PART II. 34 REACTIONS OF ANTIPYRINE. the reagent a permanent brick-red precipitate is produced, per- ceptible in a dilution of 1 in 20,000. According to Manseau (Pharm. Jour.^ [3], xx. 162), the point at which a permanent precipitate is formed is perfectly definite, and he suggests that the purity of a sample can be ascertained by titration with a standard solution of iodine. Millard and Stark {Pharm. Jour., [3], XX. 863) find that the point of permanent precipita- tion depends to a marked degree on the dilution of the antipyrine solution. Thus in a 1 per cent, solution, 1 gramme of antipyrine gives a permanent precipitate after the addition of 3 '9 c.c. of decinormal iodine, while with twice the volume of water 7*2 c.c. are required. The authors state that more concordant results are obtainable by using starch as an indicator of the end of the re- action. They dissolve 0*5 gramme of the sample of antipyrine in 200 CO. of water, add plenty of starch solution, and then drop in decinormal iodine solution gradually until a distinct blue coloration is obtained, which does not disappear on vigorously shaking or stirring the mixture. E. M ti n z e r has described an iodo-anti- pyrine, Cj^H^jINgO, which forms colourless, tasteless needles, melt- ing at 160°. An acid solution of mercuric nitrate gives a white precipitate with a solution of antipyrine. 2 c.c. of Millon's reagent and 4 c.c. of a 1 per cent, (neutral) solution of antipyrine give a white precipitate in a yellow liquid ; in a solution acid with hydrochloric acid, a yellow precipitate in an orange-yellow liquid, the precipitate eventually becoming red. In a solution ten times more dilute a yellow precipitate and green liquid result, and in an acid solution of 1 part of antipyrine in 20,000, a white precipitate and yellow liquid. 1 c.c. of a saturated solution of mercurous nitrate added to twice its measure of a 1 per cent, solution of antipyrine gives a yellow precipitate floating on a blood-red liquid. If antipyrine be heated with strong nitric acid till reaction commences, and the liquid be then allowed to cool, a fine purple coloration is produced; on adding water a violet precipitate is thrown down, and the filtered liquid is purple-red. Nitroso-anti'pyrine. Several of the foregoing reactions are probably due to the presence of nitrous acid, which (if added in the form of red fuming nitric acid) gives with a 1 per cent, solution of antipyrine a beautiful green coloration, still perceptible when diluted to 1 in 20,000 ; when the liquid is heated it becomes purple-red. In strong solutions a copious formation of small, green, needle-shaped crystals occurs. These consist of isonitroso- antipyrine, CiiII;^/N0)]S'20, and are best obtained by adding a solution of sodium nitrite to a solution NITROSO-ANTIPYRINE. 35 of antipyrine in acidulated water. The liquid at once becomes bluish green in colour, and an abundant formation of crystals speedily occurs. These may be washed with cold water, and dried at the ordinary temperature.^ Mtroso-antipyrine explodes when heated to about 200°, is nearly insoluble in water and dilute acids, soluble in alkalies and in acetic acid, moderately soluble in alcohol, and sparingly in chloroform and ether. By treatment with zinc and acetic acid it is converted into an oily base. The green coloration of antipyrine with nitrous acid is delicate and, to a certain extent, characteristic, but is common to all pyrazolones. A. C. Stark recommends that the test should be applied by dissolving potassium nitrite in a test-tube in a little water, adding excess of strong sulphuric acid, and then filling the tube with the liquid to be tested. Antipyrine dissolves without colour in pure anhydrous ethyl nitrite, but a green colour is immediately developed on addition of water. When antipyrine is added to spirit of nitrous ether containing free acid, the mixture rapidly acquires a dark-green tint, and green needles of nitroso-antipyrine separate. The reaction (which does not occur if any free acid be neutralised by potassium bicarbonate) derives practical importance from the fact that spirit of nitrous ether and antipyrine are not infrequently dispensed in conjunction. A mixture of the kind is alleged to have been fatal to the patient, but it is very doubtful if the nitroso-derivative of antipyrine was the cause of death; for direct exhibition of the compound to a small rabbit, both hypodermically and by the stomach, in doses commencing at J grain, and gradually increased to 4 grains, produced no perceptible toxic effect {Fharm. Jour., [3], xviii. 1085). Similar experiments have been made on dogs (Pharm. Jour., [3], xix. 807). Antipyrine gives a very delicate and characteristic reaction with ferric chloride, which, in a 1 per cent, solution, produces a blood-red coloration. The reaction is still very distinct in a solution of 1 in 2000, and perceptible at a dilution of 1 in 50,000. The red coloration is destroyed by excess of mineral acids. The reaction is at once given by urine containing anti- pyrine. On mixing cold aqueous solutions of antipyrine and mercuric ^ The liquid filtered from the crystals gradually changes colour from green to brown, and after standing for some hours is found to smell of hydrocyanic acid, but the quantity of this body formed appears to be very minute (Wood and Marshall, Fharm. Jour., [3], xixi 806^ 36 REACTIONS OF ANTIPYRINE. chloride, a white precipitate is formed. On boiling the liquid this disappears, but on continued boiling a brown resinoid sub- stance is deposited, which, when separated, is found to be soluble in hot alcohol and in nitric acid, and is coloured scarlet by strong sulphuric acid. Antipyrine reacts in the general manner of alkaloids. Thus, in acid solutions it gives a yellowish-white precipitate with Mayer's reagent, and the same with Marm^'s test (potassio- cadmium iodide) ; a green precipitate changing to orange-red with potassio-iodide of bismuth; an abundant reddish-yellow precipitate with Nessler's reagent ; a white with phosphomolybdate of sodium ; and an abundant white precipitate with tannin.^ According to the German Pharmaco;pceia, the solution of antipyrine in two parts of water should be neutral, free from acrid taste, and not changed by sulphuretted hydrogen water. A 2 per cent, solution should give a white precipitate with tannin; and on addition of two drops of fuming nitric acid to 2 c.c. of the solution, a green coloration should occur, changed to red on boiling and adding another drop of nitric acid. 2 c.c. of a 0'2 per cent, solution gives a deep red colour with a drop of ferric chloride solution, changed to bright yellow on adding 10 drops of sulphuric acid. Similar tests are given in the additions (1890) to the British Pharmacopoeia, in which antipyrine receives the designation "phenazone."^ Antipyrine has now an established position and wide applica- tion in medicine. Although originally introduced as a febrifuge, it is taking a still higher place as an anodyne. Given in 10 to 20 grain doses in cases of bilious and nervous headache, it often effects a remarkably rapid and perfect cure. It has been usefully injected hypodermically in 8-grain doses as a substitute for morphia; and for the relief of pain in acute and chronic gout, neuralgia, sciatica, &c. The subcutaneous injection of antipyrine is said not to be followed by drowsiness, vomiting, or excitement. It is stated to be almost a specific in puerpural fever. It has been found valuable as a haemostatic, and has proved successful in some cases of sea-sickness, but by no means invariably. Antipyrine causes an almost immediate re- ^ The reactions described in the text sufficiently indicate the pharmaceutical preparations with which antipyrine is incompatible. Thus it should not be dispensed in a mixture with nitric acid, nitrites, chloral hydrate, solid sodium salicylate, carbolic acid, tannin, iodine, mercuric chloride, salts of iron, permanganates, or tinctures or infusions of catechu, cinchona, roses, galls, rhubarb, &c. (see Millard and Stark, Pharm. Jour., [3], xx. 860). 2 Antipyrine has been adulterated with acetanilide (see page 72). ANTIPYRINE SALICYLATE. 37 duction in the temperature of the body (apparently from its influence on the brain-centres regulating the temperature), the effect continuing from four to six hours. It induces sweat- ing and feeble pulse, and in excessive doses, or even small doses in certain cases, an eruption resembling nettle-rash, occa- sionally with vomiting and collapse.^ Atropine has been found to act promptly as an antidote. Antipyrine may be detected in the urine for eighteen to twenty-four hours after it is taken by the stomach, but can be detected only for a few hours in the different organs. It has been detected, after putrefaction for a fortnight, in animals killed within two hours after its administration, either by the stomach or hypodermically. Antipyrine is readily extracted from animal matters, by rendering the liquid ammoniacal and agitating it with chloroform or amylic alcohol. Antipyrine Salicylate, CiiH^gNgOjCyHgOa. If salicylic acid be gradually added to a dilute boiling solution of antipyrine, anti- pyrine salicylate separates as a yellowish oil. The compound can be more conveniently prepared by heating equivalent proportions of antipyrine and salicylic acid with a little water to 90°, or by shaking together an aqueous solution of antipyrine with an ethereal solution of salicylic acid, when the salt separates in fine crystals. Antipyrine salicylate melts at 89°-90° C, and decomposes at a somewhat higher temperature, dissolves in 250 parts of cold water more freely in hot, and readily in alcohol, ether, chloroform, and carbon disulphide. The aqueous solution is faintly acid in reaction, and has a sweet taste and bitter after-taste. It gives a violet colora- tion with ferric chloride, and green with nitrous acid. Salicylate of antipyrine has been employed with favourable results in medi- cine under the name of " s a 1 i p y r i n." A mixture of antipyrine and salicylate of sodium gradually changes to an oily liquid on ex- posure to air. The change, which does not occur in a closed bottle, appears to be simply due to absorption of moisture by the salicylate and the solution of the antipyrine in the water thus absorbed. Antipyrine becomes pasty when mixed with betanaphthol, and appears to form a compound with phenol. Under the name of "resopyrin," Portes has described a compound obtained by mixing solutions of molecular proportions of resorcinol and anti- pyrine. It crystallises in oblique rhombic prisms, insoluble in water but soluble in alcohol. ^ The exhibition of antipyrine is unsafe when the heart is weak. A case where severe symptoms were produced by a dose of 1 gramme has been recorded bySchwabe {Pharm. Jour., [3], xx. 1059). 38 CHLORAL- ANTIPYRINE. CMoral-Antipynne, CiiHij(C2H2C]30)]N'20. When dilute solu- tions of chloral hydrate and antipyrine are mixed no perceptible reaction occurs, but on concentrating the liquid, or on mixing strong solutions of the two substances, a separation of oily globules takes place, and these immediately or gradually change to a mass of crystals of chloral -antipyrine. The same substance may be obtained by heating molecular proportions of chloral hydrate (165"5 parts) and antipyrine (188 parts) to 110°-115° C. The reaction consists in elimination of water and substitution of the group CCl3.CH(0E[) for one of the hydrogen atoms of the antipyrine ;^ but whether the replaced atom is one of those of the methyl groups, or the hydrogen atom of the CH group, is not definitely decided (compare Pharm. Jour., [3], XX. page 862 with page 889). Chloral-antipyrine, also called h y p n a 1, crystallises from alcohol in hard scales and from water in transparent rhombs. It melts at 67°-68°, is almost odourless, and has a saline taste with an after- taste suggestive of chloral. It is only slightly soluble in cold alcohol, ether, and chloroform, but somewhat more soluble in boil- ing alcohol, and is dissolved by about eight parts of warm water. The solution reduces Fehling's solution on warming, gives the blood-red reaction of antipyrine with ferric chloride, and yields chloroform when heated with dilute caustic alkali. When chloral- antipyrine is kept in a melted state for some time, it deposits crystals of a dehydration compound, which is insoluble in water, melts at 186°— 187°, and gives no colour-reaction with ferric chloride. According to Eeuter {Pharm. Jour.^ [3], xx. 602) chloral-antipyrine is physiologically inert, but B a r d e t found doses of 1 gramme to induce sleep as readily as chloral hydrate, while in cases of insomnia caused by pain it seemed to have the same anodyne effect as antipyrine. Schmidt finds the monochloral- derivative to have more decided soporific effect and a less deleterious influence on the circulation than antipyrine. Bichloral- Antipyrine is obtained by heating antipyrine with excess of a strong solution of chloral hydrate, when an oily layer is formed, which solidifies to prismatic crystals melting at 67°— 68°, soluble with some dissociation in ten parts of cold water, and giving the reactions of chloral-antipyrine. * Butyl-chloral behaves similarly with antipyrine. BASES FROM TAR. The numerous constituents of tars may be roughly divided into— (a) Indifferent Bodies : — as Hydrocarbons ; (b) Acid Bodies : — as Phenoloids and Acetic Acid ; and (c) Bases : — as Ammonia, Aniline, Pyridine, &c. The principal members of the first two groups have already been considered at length. Ammonia is beyond the scope of present work, and the remaining bases which require consideration all belong to the aromatic group. They may be arranged in several groups, each one of which is represented by a typical member. C.NHj >,CH Thus :— 1. Aniline, or Amido-benzene, CgH5.NH2, or H HC, CH CH 2. Kaphthylnmine, or Amido-naphthalene, CioH,.NH2, or . ... HC HC CH C.NHj c CH CH N CH CH 3. Pyridine, C5H5N, or 4. Quinoline, C9H7N, or HC CH CH N C. HC H 5. Acridine, CigHgN, or HC HC C CH CH CH N CH CH CH CH CH CH CH CH CH 40 ANILINE. From these formula it appears that the substitution of nitrogen is outside the ring in the case of aniline and naphthylamine. On the other hand, pyridine, quinoline, and acridine are derived from benzene, naphthalene, and anthracene respectively, by the substitution of N for one of the CH groups of the closed chain. Naphthylamine does not appear actually to exist in coal-tar, and aniline occurs in tar in very limited quantity ; these bases are obtained synthetically from constituents of coal-tar. Besides the foregoing typical bases and their allies and derivatives, certain volatile bases {e.g.^ piperidine, conine, nicotine), ordinarily prepared from plants, and therefore classed with other vegetable alkaloids, have a connection vrith pyridine or quinoline which is now fully demonstrated. ANILINE AND ITS ALLIES. Aniline is the type of a large number of organic compounds of synthetical origin. Aniline has the constitution of a mono-amidobenzene or mono-phenylamine, and may be regarded as originating in the replacement of one of the hydrogen atoms of the benzene- ring by the group amidogen, NHg ; or one of the hydrogen atoms of ammonia by the radical phenyl, CgHg. Thus : — C,H,.NH,, or (CeH,) H VN H j Aniline exists in minute quantity in coal-tar, but is ordinarily pro- duced by nitrofying benzene, CgHg, and reducing the resultant nitrobenzene, CgHgNOg, by nascent hydrogen. If the treatment with nitric acid be carried further, d i n i t r o- benzene, CpH4(N02)2, is produced, and this by reduction is converted into meta-phenylene-diamine or meta- diamido-benzene, CgH4(NH2)2. If the reduction of nitrobenzene be effected by alkaline reagents, two molecules coalesce, and azobenzene, Cgfig.N :N.CgHg, is produced. On further treatment of this (especially in alcoholic solu- tion) it is converted into hydrazobenzene, CgH5.NH.NH.CgH5, which by intramolecular change is transformed into benzidine or di-para-amido-diphenyl, NHg.CgH^.CgH^.NHg. The re- lationship of aniline to the allied bases ^ is shown below; — * Hydrazobenzene has no basic properties. BODIES ALLIED TO ANILINE. 41 Anili} e (Amidobenzene). NH,.C6H4.H Phenylene-diamine. NH2.C6H,.NH2 Benzidine. NH2.C6H,.CeH,,NH2 Aniline. C6H5.NH.H Phenylhydrazine. Hydrazobenzene. * Aniline (Phenylamine). C6H5.NH.H Diphenylamine. CeH5.NH.CeH5 Hydrazobenzene. ^ The true homo- Aniline forms two classes of homologues. 1 o g u e s (Class A) coexist with aniline in coal-tar, and are derived from aniline by the substitution of one or more methyl groups for a corresponding number of the hydrogen atoms of the benzene nucleus. They are ordinarily obtained by nitrofying the corre- sponding hydrocarbons prepared from coal-tar naphtha, and reducing the resultant nitro-derivatives. ~ Thus : — Hydrocarbon. Benzene — N itro-derivative. Nitrobenzene — Amido-derivative. Aniline — CeH^-H Toluene — Nitrotoluene — CeHj.NH, Toluidine — CeH,(CH3).H Xylene — CeH3(CH3),.H Cumene — CeH,(CH3),N0, Niti-oxylene — CeH3(CH3),.N02 Nitrocumene — CeH,(CH3).NHj Xylidine — CeH3(CH3VNH, Cumidine — CeH,(CH3)3.H CeH,(CH3)3.NO, CeH2(CH3)3.NH2 Isomeric modifications are known of all the members of the series except those in the first line (page 51 et seq.). The pseudo-homologues of aniline (Class B) are derived from aniline by the replacement of one or both of the hydrogen atoms of the amido-group by methyl or other alkyl radical. Similar substitutions can be effected in the amido-groups of toluidine, xylidine, &c. These alkylated anilines (Class B) are obtained by the action of methyl chloride or other alkyl salt on aniline, or of the corresponding alcohol on the hydrochloride or other salt of aniline (see page 73). Paratoluidine has also been obtained in a very interesting manner by heating the hydrochloride of methyl- aniline^ to 350° C. in a sealed tube, when change of position of the atoms within the molecule takes place thus : — CH3 VN = CeH/CHg) H H Para-toluidine, N H Methyl-aniline. ^ Hydrazobenzene has no basic properties. ^ If the hydriodide of methyl-aniline be similarly treated, ortho- or meta. toluidine is obtained. 42 ANILINE DERIVATIVES. By the same process methyl-toluidine may be converted inta xylidine, and this by consecutive steps into a pseudo-cumidine, isoduridine, and amido-pentamethylbenzene (page 60). By treat- ing aniline hydrochloride with aniline, diphenylamine or phenylaniline, CgH5.NH(CgH5), is obtained^ (p^ge 79). Substitution of the hydrogen atoms of aniline and its homologues can also be effected by acid or chlorous groups, both in the benzene-nucleus and in the amido-group. In the latter case the derivatives are called a n i 1 i d e s (page 67), and are quite different from the bodies resulting from the substitution of chlorous radicals for the benzenic hydrogen. In the compounds of the latter class, the basic character is either much weakened or entirely destroyed. Most of the derivatives exist in several isomeric modi- fications, according to the position of the substituting radicals in the benzene-nucleus. Examples of the bodies of this class are : — Aniline-sulphonic acid or sulphanilic acid, CgH4(S03lI).NH2 (page 49). Nitraniline, C6H4(X02).NH2 (page 50). Bromaniline, CgH^Br.NHg. Trichloraniline, CgHgClg-NHg. Mixed substitution-products, belonging at once to two or more of the foregoing classes, are obtainable by suitable means. As examples may be mentioned : — Paranitracetanilide, C6H4(N02).NH(C2H30) Paranitroso-dimethylaniline, . CgH4(NO).N(CH3)2 Paranitroso-dimethyl-paratoluidine, CgH3(CH3)(NO).N(CH3)2 The more important of the allies and derivatives of aniline formulated on this and the preceding pages are described in greater detail in the sequel. On treating aniline, and also many of the above-mentioned homologues and derivatives, with oxidising agents, a series of brilliant colouring matters are obtained, which form the well- known "aniline dyes" (Part I. page 214 e^ seg-.). By the action of nitrous acid, or a nitrite, on a cold solution of a salt of aniline a salt of diazobenzeneis obtained. This and the allied products obtained by similar means from the homologues and analogues of aniline form the starting-point of the numerous and important colouring matters known as the " a z o-d y e s " (Part I. page 175 et seq.). ' Diphenylamine and anUine hydrochloride cannot be caused to react with formation of triphenylamine, (C6H5)3N ; but this body can be obtained by the action of mono-brombenzene on di-potassium aniline : — 2C6H5Br + CeHg. NKg = {C,U,)slS + 2KBr. ANILINE. 45 By the action of reducing agents on the salts of diazobenzene, phenylhydrazine, C(5HgNH(NH2), is obtained. The body has already been fully described (page 27). Aniline.'^ Amidobenzene. Phenylamine. CeH,N = C,H,.NH, = H VN H j Aniline occurs to a limited extent ready-formed in the products of the distillation of coal, bone, and peat. Of late years a small quantity has been actually recovered from coal-tar naphtha, but almost the whole of it is obtained indirectly from coal-tar by the action of a reducing agent on nitrobenzene (" Aniline Oils," page 60). Aniline may also be obtained by passing ammonia and benzene vapour through a red-hot tube : — CgHg -|- ISTHg = Hg + CgHYN. It is also formed together with diphenylamine by the reaction of phenol and ammonia. The best yield is obtained by heating phenol to about 330° for twenty hours with ammonium chloride and magnesia or oxide of zinc (or ammonio-zinc chloride, Zn(NH3)2Cl2). Aniline is also obtained by numerous other reactions. Aniline may be purified by fractional distillation and conversion into the acetyl-derivative. This is recrystallised from water, and on saponification yields pure aniline. Pure aniline is a colourless, oily liquid, of faintly vinous odour and aromatic, burning taste. It refracts light strongly, but has no rotatory action. Aniline, when very pure, freezes at 8° C, but a slight admixture greatly reduces its solidifying point. It boils at 183°-184° C, and distils unchanged. The specific gravity of aniline is 1*0379 at 0° and 1*0216 at 20°, compared with water at 4°; and 1*0242 at 15°, compared with water at the same temperature. The coefficient of expansion is -000818. Aniline becomes yellow or brown on exposure to air and light, especially at elevated temperatures, a resinous body being ulti- 1 Aniline was first obtained in 1826 byUnverdorbenby the dry distilla- tion of indigo, and received the naime crystalline. Runge in 1834 obtained it from coal-tar, and termed it kyanol. The name aniline is due to Fritsche, who in 1841 obtained it by distilling indigo with caustic alkali. The name benzidam was given it in 1842 by Zinin, who prepared it by reducing nitrobenzene bj' sulphuretted hydrogen. The Tia,rrie phenamide h.a.s also been proposed for it. Aniline was first accurately described in 1843 by A. "W. Hofmann. 44 CHARACTERS OF ANILINE. mately formed. The change is due to oxidation, and does not occur in vacuo or in the dark.^ Aniline is only slightly soluble in water, requiring 31 parts at the ordinary temperature, but being more soluble in hot water. Water also dissolves in aniline, 5 parts being taken up by 100 of aniline at the ordinary temperature, and somewhat more at higher temperatures. The greater part can be separated by distillation, the water passing over first, but the last traces can only be removed by prolonged digestion over caustic alkali. Aniline is soluble in all proportions in a 50 per cent, aqueous solution of its hydrochloride, and in smaller proportions in more dilute solutions (see page 67). Aniline dissolves readily in alcohol, ether, wood-spirit, acetone, chloroform, carbon disulphide, and volatile hydrocarbons. Aniline is itself a solvent for sulphur, phosphorus, indigotin, camphor and colophony, but does not dissolve caoutchouc or copal. It is employed sometimes as a solvent for aniline-blue. Aniline is a powerful poison, coagulating albumin and producing symptoms similar to those caused by nitrobenzene (Vol. II. page 478).2 Aniline has marked basic properties, a long series of well-defined and crystallisable salts being obtained from it. It has, however, no action on phenol-phthalein, litmus or turmeric, though it affects a few of the more delicate vegetable colours. It expels ammonia from its salts at a boiling temperature, but is itself displaced in the cold. Aniline decomposes the solutions of many metallic salts, with precipitation of the corresponding hydroxides. When heated with strong sulphuric acid, aniline is converted into para-amido- benzene-sulphonic acid (sulphanilic acid). With hot fuming sulphuric acid, adi-sulphonic acid is produced. ^ According to A. Bidet {Compt. Rend., cviii. 520; Jour. Soc. Chem. Ind., viii. 383), aniline and toluidine prepared by the reduction of pure nitre- derivatives are colourless after distillation, and though they become yellowish in a few days, light has no further effect on them, and even this change Bidet attributes to the presence ofamido-thiophene, C4H3S. N Hg. 2 According to Letheby and Turnbull the action of aniline is chiefly on the nervous system. According to Grandhomme, the first symptom in slight cases of poisoning by aniline, caused by inhaling the vapour, is a blue colour on the edge of the lips, while the gait becomes unsteady, the speech thick, the head affected, and the face pale, while the appetite fails completely. Alcohol aggravates the symptoms. In more severe cases, such as may arise from the saturation of the clothes with aniline, the lips become dark blue or black, and the vertigo is so violent that standing becomes impossible. Accord- ing to W o h 1 e r and F r e r i c h s, aniline does not exert any poisonous action on dogs. R u n g e found the aqueous solution to kill leeches and the parts of {)lants immersed in it. REACTIONS OF ANILINE. 45 In presence of an excess of acid, aniline imparts a deep yellow colour to pine-wood and alder-pith. According to F r i s w e 1 1, on adding cupric sulphate to an aqueous solution of aniline an apple-green crystalline precipitate is formed ; or in extremely diluted solutions a green coloration. Cold aqueous solutions of aniline salts are converted by treat- ment with nitrous acid (or a nitrite and mineral acid) into salts of diazobenzene. On boiling the solution phenol is formed, with evolution of nitrogen. Under the influence of oxidising agents aniline gives products and reactions which vary considerably according to the oxidiser employed, thus : — a. When aniline is treated with excess of nitric acid, and the mixture evaporated at 100° C, the base is decomposed with forma- tion of a brown substance. With smaller proportions of nitric acid various coloured products are formed, including picric acid. b. When treated with dilute sulphuric acid and manganese dioxide, aniline yields ammonia and q u i n o n e, CgH^Og, but the greater part of the product undergoes still further change. c. If aniline be dissolved in strong sulphuric acid, and a few drops of a solution of potassium bichromate be added, a red colour is produced, which rapidly changes to deep blue. d. On treating aniline, or one of its salts in a solid state, with strong sulphuric acid, and then adding a minute fragment of man- ganese dioxide or other oxidising agent (in the manner described under "strychnine"), a fine purple coloration is produced. A better result is obtainable by employing electrolytic oxygen ; in this form the test is the most delicate and satisfactory which can be applied. e. Chlorine acts on dry aniline with great violence, producing a black mass containing trichloraniline, CgH^ClgN. Bromine behaves similarly ; and, on adding bromine-water to the aqueous solution of an aniline salt, a precipitate of tribromaniline is formed. On the other hand, Mills and Muter (Jour. Soc. Chem. Ind., iv. 96) state that aniline in solution in carbon disulphide reacts with Brg, probably forming an additive compound. /. When a solution of aniline is treated with a dilute solution of bleaching powder, avoiding excess, a fine purple coloration results, which gradually changes to brown. When carefully applied, the reaction is delicate and characteristic. The colour is destroyed by ether. g. If a minute quantity of aniline be treated with an aqueous solution of phenol, and a solution of bleaching powder be then gradually added, the reagent produces yellow striae, which change 46 DETECTION OF ANILINE. to a greenish-blue. The test, which is due to J a c q u e m i n, is said to be very delicate. h. If aniline, or one of its salts in the solid state, be treated with a drop of chloroform, and then solid potash or a strong solution of potash in alcohol be added, and the whole gently heated by immersing the tube in hot water, a peculiar and highly unpleasant odour will be produced, due to the formation of phenyl-carbamine, CgHg.NC. The reaction, which is known as " Hofmann's isonitrile test," is produced by other aromatic monamines, and by acetanilide. Detection and Separation op Aniline. The foregoing colour-reactions are amply sufficient for the recognition of aniline, provided that a proper process of separation be previously applied. Aniline may be liberated from the aqueous solutions of its salts by addition of caustic soda, and may then be extracted by agitating the liquid with ether. On separating the ethereal layer, and agitating it with dilute hydrochloric acid, the aniline passes into the aqueous liquid, which may then be concentrated or evaporated to dryness, and examined by the colour-reactions already described. From strychnine, which is the only substance with which aniline is at all apt to be confounded, it may be separated by adding caustic soda to the concentrated solution, and distilling over the aniline by driving in a current of steam. The strychnine remains in the flask, while the aniline will be found in the distillate if it be acidulated with hydrochloric acid and concentrated to a small bulk at 100° C. The same plan may be employed for detecting aniline in toxicological inquiries, or the process used for isolating strychnine may be used, but instead of evaporating the ether-chloroform it should be separated and agitated with dilute hydrochloric acid in the manner above described. F. Miiller {Jour. Chem. Soc, Hi. 514) found unchanged aniline in the urine of a person poisoned with it. The urine was optically inactive, but reduced Fehling's solution. A portion of the concentrated urine, when boiled with strong hydrochloric acid, neutralised with soda, and extracted with ether, gave an ethereal solution which showed the blue indophenol reaction. The ethereal extract of the unboiled urine did not give this reaction, a fact which Miiller believes was due to the secretion of the aniline as para-amidophenylsulphate (compare " Phenyl- Sulphuric Acid," Part I. page 9) ; a substance which is split up by boiling with hydrochloric acid. In support of this, the original urine contained sulphates (estimated by barium chloride) DETERMINATION OF ANILINE. 47 equivalent to only 0*0475 gramme of sulphuric acid per litre ; but after boiling with hydrochloric acid, 0*8085 gramme. A direct test for the presence of paramidophenylsulphates in urine consists in boiling the liquid with one-fourth of its measure of strong hydrochloric acid, adding a few c.c. of a 3 per cent, solution of phenol, and then some drops of a chromic acid solution. If para-amidophenol be present, the liquid becomes red, and turns blue on adding ammonia. The determination of aniline may be effected by evaporating its ethereal solution, or preferably by extracting the base therefrom by agitation with dilute hydrochloric acid, evaporating the acid liquid, and weighing the residual hydrochloride. Under favour- able circumstances it may be measured after liberation from a strong solution of the hydrochloride by addition of caustic alkali. instead of weighing the aniline hydrochloride, the salt may be redissolved in water, and the solution titrated with standard silver nitrate. Or it may be titrated with standard caustic alkali and phenolphthalein or litmus, as aniline hydrochloride acts on these indicators exactly like an equivalent quantity of free hydrochloric acid, and the end-reaction is perfectly sharp. The process allows of the titration of aniline in presence of neutral ammoniacal salts. On the other hand, with helianthin (methyl-orange), the basic character of free aniline is distinctly marked, but the end-reaction is not sufficiently definite to render the indicator available for accurately titrating aniline. According to Julius {Jour. Soc. Dyers, ^c, ii. 79), free aniline in aqueous solution can be satisfactorily titrated with' standard sulphuric or hydrochloric acid, if congo-red be employed as an indicator and the neutral point be regarded as that at which a bluish-violet colour is obtained, not changed by further small additions of acid; but a much larger excess is required to produce a pure blue. Results are said to be obtainable agreeing within 0"2 per cent, with theory. Salts of Aniline. Aniline combines readily with acids forming a series of salts which crystallise well. The following are the most important. Aniline Hydrochloride. Hydrochlorate of Aniline. CgHyN,Hd. This salt crystallises with great facility in colourless needles or large plates, which are very soluble in water and alcohol. It melts at 192° C, and may be sublimed unchanged. It yields double salts with stannic, mercuric, antimonious, platinic and auric chlorides ; aniline chloroplatinatej {C^^l^,T{.C\)^tGl^y crystallises from hot water in yellow needles. Aniline salt is 48 ANILINE SALT. the ordinary commercial name for aniline hydrochloride. It is manufactured by mixing the calculated weights of aniline and hydrochloric acid in stone-tanks, freeing the crystals formed from the mother-liquor by a centrifugal machine, and drying them. According to another process, aniline is dissolved in petroleum spirit of 0"720 specific gravity, and hydrochloric acid gas passed in till the solution is saturated. The aniline salt is deposited as a white powder, which is separated from the adhering petroleum spirit by hydraulic pressure, and ground to powder. Aniline salt is employed largely in calico-printing, its chief use being for the production of aniline-hlack (Part I. page 250). It is important that the salt intended for this purpose should be made from pure aniline, and should be dry and neutral. The presence of free acid in the aniline salts is liable to cause the cloth dyed black to rot in the steaming process. It must be free from sand or grit, which would injure the printing rollers, and will produce streaks on the printed cloth. GhHt remains undissolved when the sample is treated with hot water, and may be filtered off, dried or ignited, and weighed. Free acid is best determined by titration with decinormal caustic alkali, using methyl-orange as an indicator, but the results are not very satisfactory. A useful method of examination consists in titrating the aqueous solution of 2 grammes of the sample with normal caustic soda, using litmus or phenolphthalein a& an indicator. The amount neutralised corresponds to the total acid, both free and combined with aniline. Theoretically, 2 grammes of pure aniline hydrochloride would require 15*4 c.c. of normal caustic soda, but owing to the presence of toluidine and moisture commercial samples of good quality require between 14 and 15 c.c.^ The process will indicate the presence of ammonium chloride, which will not neutralise alkali, and hence a sample containing it will require a less volume of the standard solution. Ammonium chloride is occasionally met with in considerable proportion as an adulterant of aniline salts. For its accurate determination the sample should be dissolved in water, excess of caustic soda added, the liberated aniline separated, and the aqueous solution distilled in the usual way. On titrating the distillate with standard acid and litmus or phenolphthalein, only the ammonia will be indicated. Fixed impurities will be detected on igniting the sample ; a mere trace should be present. An idea ^ This method of examining aniline salts is due toR. "Williams {Chem. News, 1. 299), but he appears to attribute the reaction to the presence of free acid. ANILINE-SULPHONIC ACIDS. 49 of the proportion of tohddine present in the sample can be obtained by liberating the mixed bases from the solution of the salts by caustic soda, and heating a few centimetres of the aniline with an equal quantity of strong arsenic acid solution to 180° C. for some time. On boiling the product with water, the intensity of the crimson coloration will increase with the proportion of toluidine in the sample. A more accurate result can be obtained in the manner indicated on page 64. Aniline Sulphate, (CgH7N)2H2S04. This salt forms a crystal- line powder, which is readily soluble in water and slightly so in alcohol. It is insoluble in ether, a fact which distinguishes it from the sulphate of methylamine. Aniline Oxalate, (CgH7]Sr).,H2C204, is very slightly soluble in cold water or alcohol, and insoluble in ether. Aniline Acetate, CgH7N,HC2H302, does not appear to have been obtained in a crystalline form. When heated it loses the elements of water and forms acetanilide (see page 68). Aniline-sulphonic Acids. Amidobenzene-sulphonic Acids. When aniline is treated with an equivalent amount of dilute or concentrated sulphuric acid it is converted into aniline sulphate If an excess of acid be used, a high temperature employed, or sul- phuric anhydride be present, aniline-sulphonic acid is produced: — CeH,.NH, + SO,(OH), = C,H, { ^^'^^ + H.OH Three modifications of this body exist, which differ according to the relative positions of the NHg and SO3H groups in the benzene- chain. The ortho-sulphonic acid (1:2) has no practical interest, but the m e t a- and par a-acids are manufactured on a large scale for the production of aniline- and azo-dyes. Meta-amidohenzenesulphonic Acid, CgH^(NH2)^^>.S03lI(^), is em- ployed for the manufacture of metanile-yelluio (Part I. page 190). It is prepared by warming nitrobenzene with fuming sulphuric acid, or by treating a solution of benzene in strong sulphuric acid with fuming nitric acid, when a mixture of nitro-benzenesul- phonic acids, CgH^(N02)S03H, is obtained, in which the meta-acid predominates, and may be roughly separated from its isomers by conversion into the barium or calcium salt. The meta- nitro-sulphonic acid yields, on reduction, the corresponding amido- sulphonic acid. Para-amidobenzenesulphonic Acid, CgH4(NH2)(^).S03HW, likewise called Sulplianilic Acid, is prepared on a large scale by heating one part of aniline and three of concentrated sulphuric acid to 195°. With fuming acid, the reaction occurs more rapidly and at a VOL. III. PART II. D 50 NITRANILINES. lower temperature. On pouring the cooled product into water, the acid separates as a crystalline mass, which can be recrystallised from hot water. Sulphanilic acid crystallises in rhombic tables containing 1 aqua, which effloresce in the air, and are only slightly soluble in cold, but readily in hot, water, Treatment with potassium bichromate and sulphuric acid oxidises it to q u i n o n e, CgH^Og. The solution of the sodium salt, on treatment with sodium nitrite, yields sodium diazobenzenesulphonate (Part I. page 177). Aniline sulphanilate gives off all its base at 100°. NiTRANiLiNES. When aniline is treated with dilute nitric acid it yields aniline nitrate. With the concentrated acid it reacts far more violently than benzene, and is converted into q u i n o n e and other products. To obtain a nitro-derivative by such means, the aniline must be protected by employing its acetyl-derivative, or by nitrofying in presence of excess of strong sulphuric acid. In the latter case a mixture of the three isomeric nitranilines is obtained, but chiefly the me^a-compound ; in the former case pai^a- nitracetanilide, CgH4(N02).NH(C2H30), is formed, together with some of the 07'^^o-compound, both of which readily yield the corresponding nit r aniline, CgH4(N02).NH2, on boiling with concentrated hydrochloric acid or caustic alkali. Another method of preparing the nitranilines, especially the meta- modifi cation, is the reduction of the corresponding dinitrobenzenes in alkaline alcoholic solution. Under these circumstances only one of the NOg groups is reduced to NHg, whereas in acid solu- tions diamidobenzene, CgH^ : (NH2)2, is obtained (page 86). Nitranilines, C6H4(N02).NH2 . Ortho. Meta. Para. Appearance and \ Crystalline form,) N02:NH2=1:2 N02:NH2=l:3 N02:NH2=1:4 Orange-yellow needles. Long yellow needles. Long yellow needles. Taste ... Sweet, burning. Nearly tasteless. Melting-point, . . 71' 114° 147° VolatUity, . . . Distils in a current of steam. Sublimes at 100°. Distils in a cur- rent of steam. Not volatile with steam. Salts Very unstable. Fairly stable. Unstable. Behaviour when boiled with strong soda, ••• Unchanged. Forms para-nitro- phenol— C6H4(N0.,).0H The nitranilines are yellow crystalline bodies, readily soluble in alcohol but only slightly so in water. They are weak bases form- HOMOLOGUES OF ANILINE. 51 ing yellow salts, and yield the corresponding diamidobenzenes on reduction. The preceding table exhibits their chief differences. Two dimtramUnes, CgH3(]S'02)2.NH2, are known, melting re- spectively at 1 82° or 1 38°. Also a tnnitranUine, C^j^^0^^.^n^ or picramide, which melts at 186°, and is converted into picric acid, 05112(^02)3.011, and ammonia when boiled with caustic alkali. Homologues of Aniline. As already stated, the true homologues of aniline are bodies in which one or more atoms of the hydrogen of the benzene-nucleus are replaced by a corresponding number of atoms of methyl or other alkyl radical. The compounds in question may be prepared, and are produced commercially, by processes exactly similar to those which result in the formation of aniline. That is, the hydro- carbons toluene, xylene, &c., are treated with nitric acid, and the resultant nitro-derivatives are reduced to the bases by nascent hydrogen (usually iron and hydrochloric acid). In their general chemical relationships the homologues present the closest resemblance to aniline, and yield substitution-products of a strictly parallel character. They are also diazotised similarly. The only homologues of aniline which require separate descrip- tion are the toluidines, C^HgN, and the xylidines, CgHj^^N. Their consideration will be followed by a section describing " aniline oils," under which term is included commercially pure aniline and toluidine, and various mixtures of these bases. Toluidines. Amidotoluenes. Amido-methylbenzenes. Tolyl- amines. C7H9N = C7H7.NH2 = C6H,(CH3) 'H3)) H VN H j The toluidines exist in small quantity together with aniline in coal-tar. They are produced commercially from toluene by processes exactly analogous to those by which aniline is prepared from ben- zene, and together with aniline constitute nearly the whole of the " aniline oils " of commerce (page 60). An interesting method of producing toluidine is mentioned on page 41. Three isomeric modifications of toluidine are known. The chief physical differences between them are shown in the following table, in which they are also contrasted with aniline and their meta- meride benzylamine, CgHg.CHgNHg.^ '^ Benzylamine is a colourless liquid of faint aromatic odour, and is not affected by light. It is miscible in all proportions with water, alcohol and 52 ISOMERIC TOLUIDINES. Aniline. Ortho- toluidine. CH3:NH2 = 1:2 Meta- toluidine. CH3:NH2 = 1:3 Para- toluidine. CH3:NH2 = 1:4 Bemylamine. Specific gravity at 15°, 1-0268 1-0037 0-998 (at 25°) Solid. -990 Melting-point, . Solidifies at -8°0. Does not soli- dify at -20° Does not soli- dify at -13° Melts at -1-45° Liquid. Boiling-point, 183°-7 199° 197° 198° 185° Characters of the acetyl-deriva- tive :— Melting-point, 114* 107' 65°-66° 147° 57'-61' Boiling-point, 295° 296° 302°-304° 307° 300° 1000 parts of water dissolve, 3-4 at 14° 8-6 parts at 19° 4-4 parts at 13° 0-89 at 22° Soluble. Solubility of the acid oxalate :— In 1000 parts of water at 15°, .. 28-8 26-5 8-7 In 1000 parts of ether at 15°, ... 0-50 Very slight. 0-016 ... Ortho- toluidine is formed by the reduction of ortho-nitro- toluene. It is a colourless liquid, turning brown on exposure to air or light, and otherwise closely resembling aniline. It •differs from its isomerides by giving a green coloration when treated with ferric chloride and a little para-diamidobenzene. A solution of 1 in 10,000 gives a fairly deep coloration, and one of 1 in 100,000 assumes a distinct greenish tint. All commercial aniline gives this reaction, and even that prepared by the distillation of indigo with caustic alkali. Meta-toluidine is produced by the reduction of meta-nitrotoluene, preferably by an acid solution of stannous chloride. It is only present in small proportion in commercial toluidine. For its detection and approximate determination the mixed bases are ■converted into hydrochlorides, and the greater part of the isomeric salts removed by fractional crystallisation. The mother- liquor is evaporated to dryness, and the residue heated with methyl alcohol to 200°, under pressure, for a considerable time. This produces a mixture of the three isomeric dimethyl-toluidines. •ether, but is separated from its aqueous solutions by caustic alkalies (con^pare "Pyridine "). It lias a strongly alkaline reaction, fumes with hydrochloric acid, and absorbs carbon dioxide from the air, with conversion into silky needles of the carbonate. DISTINCTION OF TOLUIDINES. 53 but only the meta-modification yields a nitroso-derivative, CgH3(NO)(CH3).N(CH3)2, on adding sodium nitrite to an ice-cold solution of its hydrochloride. The hydrochloride of nitroso- dimethylmetatoluidine thus prepared, crystallises from a hot acidulated solution in greenish-yellow needles only slightly soluble in cold water. On treatment with sodium carbonate the free base is obtained, melting at 92°, crystallising from water or ether in small green plates or long needles, and precipitated in moss-green needles on adding petroleum ether to its chloro- formic solution. All its solutions have a deep green colour. Nitroso-dimethylmetatoluidine forms steel-blue compounds with aniline and orthotoluidine. According to Rosenstiehl, the three modifications of toluidine may be distinguished by the following reactions : — Orthotoluidine. Metatoluidine. Paratoluidine. 1. To a solution of the Blue coloration Yellow-brown Yellow coloration. base in sulphuric changing on coloration, be- acid, of 1-75 sp. dilution to a coming greenish- gr., add a solution permanent red- yellow on slight of chromic acid in violet. dilution, and sulphuric acid of colourless on the same strength. further addition of water. 2. To a solution of Orange coloration, At first red, rapidly Blue streaks which the base in sul- or in very con- changing to in- soon tinge the phuric acid of 1-75 centrated solu- tense blood-red. whole liquid ; (in sp. gr., add nitric tions, brown, be- and then dirty presence of ani- acid. coming yellow on red ; on dilution, line or ortho- dilution. orange. toluidine, blood red). The colour quickly becomes violet, then red, and, after some hours, brown. 8. Dissolve the base The aqueous layer The aqueous layer No reaction. In in ether, and add becomes first yel- becomes a thick presence of ani- an equal volume of low and then brownish-yellow. line the ether water. Then add brown. The The ethereal becomes blue on a few drops of clear ethereal layer. layer becomes agitation. solution of bleach- after separation. reddish, and ing powder. gives a per- after separation manent reddish- and addition of violet coloration dilute sulphuric with dilute sul- acid is coloured phuric acid. violet at the under-surface. Para-toluidine is produced by the reduction of the nitrotoluene derived from the toluene produced by the dry distillation of Tolu balsam ; also by heating paracresol to 300° with ammonia and chloride of zinc ; and by molecular transposition from methylaniline hydrochloride (page 41). It crystallises from hot 54 COMMERCIAL TOLUIDINE. dilute alcohol in colourless plates melting at 45°, and has a peculiar odour recalling that of aniline. Commercial Toluidine consists chiefly of a mixture of the ortho- and para- modifications. According to Friswell, the specific gravity of the orthotoluidine of commerce should be about 1-0037, and its boiling-point from 197° to 198° C. It ought not to solidify on cooling to — 4°, though the majority of samples contain sufficient paratoluidine to cause them to commence crystallising at this temperature. The paratoluidine of commerce occurs in white dry crystals, melts at 43°-45°, and distils between 196° and 198°. Liquid commercial toluidine should boil at 197°-198°, have a specific gravity of about 1*000, and contain from 30 to 40 per cent, of paratoluidine and 60 to 70 of orthotoluidine. A portion of the para-modification separates from the com- mercial mixture of the isomers when the liquid is cooled by a freezing mixture. A further separation is effected in practice by fractionally saturating the mixture of the bases with sulphuric acid, and then distilling in a current of steam. Orthotoluidine being a weaker base than the para-compound, the former will alone pass into the distillate if the quantity of sulphuric acid employed be somewhat in excess of that requisite to neutralise the paratoluidine. L. Lewy {Jour. Chem. Soc, 1. 872; Jour. Soc. Chem. Ind., V. 481) has proposed to separate ortho- and para- toluidine by converting the bases into phosphates. It appears that when para- toluidine and orthophosphoric acid are brought together, c?2.'-toluidine orthophosphate, (C7H9N)2ll3P04, is produced as a salt crystallising in scales and very sparingly soluble in cold water, but more readily, with partial dissociation, in boiling water. Aniline acts simi- larly, forming a sparingly soluble di-amlmG orthophosphate, (CQHyN)2H3P04. On the other hand, orthotoluidine forms a mowo-toluidine orthophosphate, (C7ll9N)H3P04, and never a di- or tri- salt. Hence in the phosphates obtained from a mixture of the two toluidines the proportions of the bases might be deduced from the percentage of phosphoric acid. The mono-orthotoluidine phosphate is more readily soluble in water than dipara toluidine or dianiline phosphate. Further, when its solution is shaken with free aniline or paratoluidine, the orthotoluidine is set free. Hence pure orthotoluidine can be obtained from commercial toluidine^ by adding rather more of a 21 per cent, aqueous solution of phosphoric acid than will suffice to form diphosphates ^ The xylidines and cumidines behave like orthotoluidine, and form only monophosphates. SEPARATION OF TOLUIDINES. 55 with the aniline and paratoluidine present. On warming the liquid, the free orthotoluidine forms a layer at the surface, which may be separated and distilled. The process may be modified by adding a further quantity of phosphate to convert the ortho- toluidine into monophosphate, and then cooling the liquid aiid allowing it to stand to secure the complete deposition of the paratoluidine phosphate. ■ Wolfing (^e?-., xix. 2132) states that orthotoluidine pre- pared by Lewy himself by the above process, both on the small and large scale, still contained as much as 4 per cent, of para- toluidine. For the preparation of pure paratoluidine he recom- mends (Dingl. Polyt. Jour., cclxiii. 260) that the hydrochlorides of the bases should be treated with an amount of sodium nitrite only sufficient to convert the orthotoluidine present into a m i d a z 1 1 u e n e. Only when this change is complete does the paratoluidine react with the nitrite to form a diazo- amido-com})ound. A method of determining the proportions of the ortho- and para- moilifications of toluidine in the commercial product has been based byRosenstiehl on the different solubilities of the acid oxal- ates of the two bases. The acid oxalate of paratoluidine requires 6660 parts of ether for solution, while the corresponding salt of ortho- toluidine dissolves in 200 parts of ether. The method, somewhat modified, is as follows : — 0'2 gramme of the sample is dissolved in 80 c.c. of anhydrous ether free from alcohol; 1 059 gramme of anhydrous oxalic acid, or 1*177 gramme of the crystallised, acid is dissolved in 250 c.c. of anhydrous, alcohol-free ether. Each c.c. of this solution will precipitate 0*005 gramme of toluidine. An excess is added to the ethereal solution of the sample, the liquid allowed to stand in a stoppered bottle for twelve hours, then filtered through paper, and the precipitate washed with ether. The precipitate is then washed into the bottle with water, and tho solution titrated with decinormal caustic alkali and phenolphthalein. 1 CO. of decinormal alkali represents 0'00535 gramme of para- toluidine. ^I i n i a t i. Booth, and Cohen {Jour. Soc. Chem. Ind., vi. 419) find that if too long a time be allowed for the pre - cipitatioi), the product is liable to contain the orthotoluidine oxalate, and hence the result will be above the truth. They recommend that a repetition of the experiment should be made, in whicli the amount of oxalic acid solution used is only that requisite to combine with the paratoluidine found by the first test', so reducing the error to a minimum. G. Lunge {ChemiscJie Ind., viii. 74; Jour. Soc. pTjers^^c^ I 150) estimates the proportion of para- and ortho-toluidine in a 56 DENSITY OF TOLUIDINES. mixture of the two by a careful observation of the specific gravity. The determination is made by the bottle, and referred to water at 15° C. If the sample does not contain more than 50 per cent, of paratoluidine it is liquid at 15°, and consequently the observation is made at that temperature. With 50 to 60 per cent, of para- toluidine the method is still available if the bottle be filled at 20° C. ; but with still larger proportions the results are unreliable, as the correction for temperature loses in accuracy, and the differences in specific gravity become very small for considerable alterations in the composition of the mixture. It is very desirable to adhere rigidly to the prescribed temperature, as an error of 1° C. causes an error of 7 per cent, in the estimation. The correction is zh 0'0008 for 1°, when the density is above 1*0008, and ± 0'0007 when below that point. All water must be removed by treating the sample with powdered caustic potash and redistilling. The distillation also serves to show the presence of analine or xylidine, in presence of notable quantities of which the method is inapplicable. Lunge gives the following table of densities of mixtures of para- and ortho-toluidine, water at 15° being taken as unity : — Specific Ortho- Specific Ortho- Specific Ortho- Specific Ortho- gravity at toluidine. gravity at toluidine. gravity at toluidine. gravity at toluidine. 16- C. Per cent. 15- C. Per cent. 20° C. Per cent. 20° C. Per cent. 10037 100 1-0016 82J 0-9995 65J 0-9939 50 36 99 15 82 94 65 38 49i 35 98 14 81 93 64 37 48J 34 97 13 80 92 63 36 48 33 96 12 79J 91 62 35 *7J 32 95 11 ?,1 90 61J 34 46i 81 94 10 89 61 33 46 80 93i 09 77 88 60 32 45 29 ^1 08 76 87 59 31 44i 28 07 75 86 - 58J 30 44 27 91 06 74 85 58 29 43 26 90 05 73 84 57i 28 42 25 89i 88} 04 72i 83 56i 27 41 24 03 72 82 56 0-9926 40 23 88 02 71 81 55 22 87 01 70 80 54i 21 86J 1-0000 69 79 54 20 86 0-9999 68J 78 63 19 85 98 68 77 52^ 1 18 m 97 67 76 51i 1 1.0017 83i 0-9996 66J 0-9975 51 A method of separating orthotoluidinefrom paratoluidine has been based by P. Schoop (Chem. Zeit, ix. 1785; Jour. Soc. Chem. Ind.y V. 178) on the observation of We ith and Merz, that the acetyl-derivative of orthotoluidine is far less soluble in water than that of the isomer and of aniline. Schoop's method has been found unsatisfactory by several chemists, and need not be further described. A method of estimating paratoluidine in admixture with ortho- XYLIDINES. 57 toluidine has been based by G. A. S c h o e n (Chem. Zeit, xii. 494 ; Jour. Soc. Chem. Ind., vii. 594) on the intensity of the red colour produced with potassium bichromate. If the specific gravity indicates the presence of more than 8 per cent, of paratokiidine it is reduced below that proportion by adding orthotoluidine. 1 c.c. of the oil is then dissolved in 2 c.c. of hydrochloric acid and 30 of water, and 1 c.c. of a cold saturated solution of bichromate of potassium added. The mixture is allowed to stand for an hour, with occasional stirring, and is then filtered. Orthotoluidine gives a black lake and a colourless liquid, but in presence of para- toluidine the precipitate is light brown, and the filtrate has a red colour, intense in proportion to the paratoluidine present. Pure aniline behaves like orthotoluidine, but in presence of the latter a red filtrate is produced. Hence aniline must be absent, or its amount must be deduced from the boiling-point and specific gravity of the sample, and a corresponding amount added to the standard mixture with which the sample is compared. Xylidines. Amido-dimethylbenzenes. CgH3(CH)2.NH2. Six isomeric bodies of the above formula are theoretically pos- sible, and all of them are known. Thus :^ — Base. Positions of Groups. CH3:CH3:NH2 Boiling- Point, • C. Acetyl-Derivative. Characters of Hydrochloride. Melting- Point, • C. Appearance, &c. »-Orthoxylidine, o-Orthoxylidine, r-MetaxyUdine, a-MetaxyUdine, a-Metaxylidine, Paraxylidine, 1:2:3 1:2:4 1:3:2 1:3:4 1:8:5 1:4:2 223 226 (melts at 49) 214 212 220 212*5 134 99 176-8 129 140-5 139 White needles. Long vitreous prisms. White needles ; not saponi- fied by boil- ing alkali or acid. White needles. Large flat needles. Long lustrous needles. Moderately sol- uble white needles, con- taining 1 aq. Long, very thin prisms, con- taining 1 aq. Thin anhydrous plates; readily soluble. Anhydrous rhom- bic tablets ; slightly sol- uble in cold water. Large anhydrous needles. Flat needles or large tablets. ^ The tabic is chiefly drawn up from the descriptions of the isomeric xyli- dines given by R o s c o e and Schorlemmer (iii. part i v. page 406). The 58 XYLIDINES. TJie modifications of xylidine produced by nitrofying the xylenes of coal-tar naplitlia and reducing the nitro-derivatives are chiefly a-orthoxylidine, a-metaxylidine, and paraxylidine, but two of the other isomers are also said to be produced. Only the a-meta- modification is of any value for the manufacture of azo-colouring matters, and of the cumidines, C0H2(CH2)3.NH2, which are prepared by heating xylidine hydrochlorides with wood spirit. On this account, the useless isomers are removed as far as possible from the metaxylene before nitrofying (Vol. II. page 482), and in fact the presence of even a few units per cent, of orthoxylene will occasion coii?iderable practical inconvenience by the formation of tarry matters during its conversion into xylidine. On the other hand, commercial xylidine often contains as much as 25 j)er cent, of paraxylidine. v-metaxylidine (1 : 3 : 2) is prepared by convert- ing commercial xylidine into the sulphate, which is allowed to crystallise, and the base liberated from the mother-liquor by alkali. The fraction distilling between 212° and 216° is heated with acetic anhydride. The v-m eta-acetxylidide formed is not acted on by boiling for several hours with four times its weight of dilute sulphuric acid containing 25 per cent, of HgSO^, but its isomers are decomposed. On cooling, the unchanged acetyl-com- pound separates, and after recrystallisation from hot water melts at characters differ considerably from those attributed to the isomers by Wroblewsky {Annalen, ccvii. 91). Nolting and Pick {Berichte, xxi. 3150), however, consider that Wroblewsky's -y-orthoxylidine was simply impure ■y-nietaxylidine, and give the following table of characters of xylidine salts : — v-Orthoxylidine. as-Orthoxylidine. r-Metaxylidine. Wroblewsky's so-called Orthoxylidine. Hydrochloridk, . -t-lHaO 4-IH2O -I-JH2O; needles -f-JHaO Solubility in 100 of water at 18° C, 11-2 Very soluble. 9-2 Very soluble. Nitrate, . Anhydrous. Anhydrous. Anhydrous. Anhydrous. Solubility in 100 of water at 18° C, 6-6 0-4 2-2 27 XoRMAL Sulphate, Anhydrous. Anhydrous. Anhydrous. Anhydrous. Solubility in 100 of water at 18° C, 1-4 5-6 Very soluble. ... ACID Sulphate, . Is not formed under ordinary tions. + 2i HaO + 2i H2O Solubility in 100 of water at 18° C, 6-2 Very soluble. XYLIDINES. 59 176''*8 C. On heating it for some time to 200° C, with three parts of sulphuric acid containing 70 per cent, of HgSO^, the sulphate of u-metaxylidine is formed. This salt differs from the sulphate of the isomeric xylidines in its very ready solubility in water. a-Orthoxylidine (1:2:4) is the only modification of xylidine which is solid at ordinary temperatures. By gradually evaporat- ing its solution in petroleum ether, it is obtained in thick mono- clinic prisms, but when rapidly deposited, or caused to solidify quickly, it forms transparent vitreous tablets. It melts at 49°, and is sparingly soluble in cold water, but readily in hot water, and also in alcohol and ether. Its aqueous solutions are not coloured by bleaching powder solution. The hydrochloride is readily soluble in water, but only slightly in strong hydrochloric acid ; its aqueous solution imparts an intense yellow colour to fir-wood. a-MetaxijUdine (1:3:4), or ordinary xylidine, is best obtained by converting commercial xylidine into the hydrochloride and crystallising the product from water. Both the hydrobromide and hydrochloride are only slightly soluble in cold water. The last traces of impurity can be removed from metaxylidine by convert- ing it into the acetyl-derivative, and recrystallising this body from benzene till it has a melting-point of 129°. It is then decomposed by sulphuric acid. Paraxylidine (1 : 4 : 2) has a specific gravity of 9 80. It is prepared by treating commercial xylidine with fuming sulphuric acid containing sufficient sulphuric Mihydride to convert the bases into sulphonic acids. The mixture is heated to 100° for some time, allowed to cool, and the solid mass pressed under water to separate metaxylidine-sulphonic acid in the crystalline state ; or the hot liquid is poured upon ice, when the metasulphonic acid, being with difficulty soluble in dilute sulphuric acid, crystallises out. The mother-liquor is neutralised with chalk, filtered, precipitated with sodium carbonate, and again filtered. On concentrating the filtrate, the sodium salt of paraxylidine-sulphonic acid separates in nacreous plates, which are washed with a little cold water to free them from traces of the readily soluble meta-sul- phonate. The salt yields paraxylidine on dry distillation with am- monium chloride, while the sodium salt of metaxylidine-sulphonic acid chars under the same treatment. Paraxylidine may also be obtained by nitrofying and reducing paraxylene, which may readily be prepared from commercial xylene (Vol. II. page 483). CuMiDiNES. Amido-trimethylbenzenes. 0^112(0113)3. NHg. Various isomerides of this formula are known. The solid variety of commercial cumidine is made by heating xylidine hydro- chloride and methyl alcohol together under pressure, to about 300°. 60 ANILINE OILS. The bases are liberated and converted into nitrates, and the difficultly soluble nitrate of pseud ocumi dine separated from the mother-liquor. The base is again liberated and distilled. The fraction passing over between 230° and 240° crystallises on cool- ing, and consists of amid o-p seudocumene : — (CHg : CHg : CHg : NH2= 1 : 2 : 4 : 5). It crystallises from hot water in long needles, and from alcohol in large prisms, melts at 68°, and boils at 234°-236°. When con- verted into diazocumene it can be used for the preparation of azo-colours by reaction with naphthol-mono- and di-sulphonic acids. IsoDURiDiNE. Amido-tetramethylbenzene. CgH(CH3)4.NH2. When the hydrochloride of pseudocumidine is heated with methyl alcohol to 300°, the hydrochloride of isoduridine is formed. The free base, which also occurs among the bye-products of the manufacture of pseudocumidine. is an oily liquid which boils at 250°-253°, and solidifies on cooling to crystals which melt at 14°. Amido-pentamethylbenzene. Cg(CH3)^.K^Il2. This base is obtained by heating dimethyl-a-pseudocumidine with methyl iodide. It forms large white needles, melting at 151° and boiling at 277°. Aniline Oils. The term " aniline oils" is applied commercially to all the different varieties of aniline manufactured on a large scale, equally whether the product in question consists of nearly pure aniline, of toluidine, or of a mixture of the two. The method of manu- facturing the different varieties of aniline oil is substantially the same, the composition of the product depending on that of the hydrocarbon employed. The details of the method of manu- facture are, of course, subject to variation, but the following is an outline of the method pursued in a well-known aniline works : — Crude coal-tar naphtha is redistilled to a temperature of 170° C. The product of the distillation, called "once-run naphtha," is treated with strong sulphuric acid (sp. gr. 1*845) which removes the bases, hydrocarbons of the ethylene and crotonylene series, and some of the highei homologues of benzene. A subsequent treat- ment with milk of lime or caustic soda eliminates the phenols and other bodies of an acid character. The purified oil is washed with water and redistilled to obtain "50/90 benzol," and this when fractionated with the acid of a dephlegmating column at once yields 99 per cent, benzol, toluol, and solvent naphtha (compare Vol. II. page 487). Solvent naphtha is now generally further treated for the isolation of xj'lene, but the benzols and toluol are directly converted into the nitro-compounds by placing them MANUFACTURE OF ANILINE. 61 in a vessel surrounded with cold water, and gradually running in a cold, previously made mixture, of 150 per cent, by weight of nitric acid of 1*4 specific gravity with 200 per cent, of concentrated sul- phuric acid. When the reaction is complete the mixture is allowed to stand, and the lower layer of acid is tapped off and concentrated again in glass for repeated use. The nitrohenzol is washed several times with caustic soda, and then treated with open steam to drive off unchanged benzol and "light stuff." The nitrobenzol (or nitrotoluol obtained in a precisely similar manner) is then placed in a still with hydrochloric acid, and borings or filings of grey cast iron added gradually. High-pressure steam is blown in, and the nitrobenzol which distils over is separated from the condensed water, and returned to the still until the complete solubility of the distilled oil in hydrochloric acid shows that the reaction is complete. Milk of lime is then introduced, and the liberated aniline distilled off by the aid of steam. Aniline sinks to the bottom of the con- densed water, but when toluidine is being made the oil floats on the surface. The condensed water contains from 2 to 3 per cent, of dissolved bases, and is converted into steam for the aniline stills. The iron is converted into a black paste, consisting chiefly of FegO^, which is sold for purifying gas. The aniline oil is distilled to separate water, &c. The addition of lime to liberate the aniline is not strictly necessary, and in many works it is omitted. The first reaction seems to be : — CeHg.NOg + Feg -f- 6HC1 = SFeClg + CgHg.NHg + 2H2O. The ferrous chloride formed also acts as a reducing agent, being converted into ferric chloride, which in presence of water gives ferric oxide and aniline hydrochloride. The end-products are chiefly aniline, ferroso-ferric oxide, and a weak solution of ferrous chloride. The hydrochloric acid seems to act chiefly as a carrier, so that the general reaction may be represented by the equation : — 4C6H5.NO2 + 9Fe4- 4H2O = SFcgO^-l- 4C6H5.NH2. Acetic acid was formerly employed in place of hydrochloric acid, but its use is now almost, if not entirely, obsolete. Its use in too large a proportion tended to the formation of acetanilide. Too large an excess of iron, or its too rapid addition, may cause loss from a reproduction of benzene, while deficiency of both iron and acid favours the production of azo-benzene. Composition and Assay op Aniline Oils. There are three leading kinds of aniline oil now recognised in the market, namely: — (1) Pure aniline oil; (2) aniline oil for red; and (3) toluidine. The demand for xylidine for the manufacture of azo-reds has considerably influenced the character 62 VARIETIES OF ANILINE OIL. of commercial aniline; since the 50/90 benzol, which was commonly used for the manufacture of " aniline for red," formerly contained a notable quantity of xylene, which is now removed and converted separately. Since the employment of dcphlegmating columns has become usual, benzene and toluene of almost constant boiling-points have been manufactured. From the pure hydro- carbons the corresponding bases are prepared, while from the inter- mediate oil, containing about 25 per cent, of benzene and 75 of toluene, an aniline oil for red is manufactured, which contains about 25 per cent, of aniline, from 20 to 25 of paratoluidine, and 45 to 50 per cent, of orthotoluidine.^ In addition to the foregoing leading qualities of aniline oil, products of very varying composition and degrees of purity have to be dealt with by the dye-manufacturer. Thus in making magenta by the arsenic acid process, fully one-fourth of the aniline distils off and is condensed. But this recovered aniline is found on rectification to have a considerably higher density than the original oil (1-015 to 1*009 against 1'0075), and to consist almost entirely of aniline and orthotoluidine, whereas the original oil contained from 15 to 25 per cent, of para- toluidine. This is either employed for the manufacture of safranine or very red shades of blue, or crude paratoluidine is added to it in such proportion as to bring it approximately to the original composition. Similarly, in the manufacture of magenta by the nitrobenzene process, the recovered aniline contains notable quantities of nitrobenzene, while from other processes methylated and ethylated anilines are obtained. Re- covered anilines are deeper in colour and of greater body than unused oils, and often have a strong and somewhat characteristic odour. They are rarely met with outside the colour- works in which they have their origin. On next page is a tabulated list of the more important or frequently-occurring constituents of aniline oils.^ With the ex- ception of aniline and its homologues, and the substituted anilines, very little is known respecting the effect of the bodies formulated in the table on the colouring matters produced. For the most part the objectionable impurities are got rid by fractionating the crude aniline oil. ^ The composition of aniline oil for red is often judged of by the consumer solely from the specific gravity, and he or the aniline-maker adjusts it accord- ingly by adding aniline or toluidine to the crude oil as the gravity may indicate. 2 Hell and Rockenbach {Ber., xxii. 505) have investigated some other non-basic constituents of aniline and toluidine tailings. CONSTITUENTS OF ANILINE OILS. 63 Name. Formula. Melting- Point 'C. Boiling- Poirit 'C. Remarks. Aniline, . C6H6.NH2 - 8 183-7 See page 43. T^i„5 (ortho-; 1 :2 ) ( below - 20 199 - See page 52. C6H4(CH3).NH2 ] below -13 197 ) i 45 198 Xylidine (several isomers), Cen3(CH3)2.NH2 ... 212-226 See page 57. Cumidine (several isomers, chiefly Pseudocumidine), C6Ho(CH3)3.NH3 63 235 See page 60. Methyl-aniline, C6H5.NH(CH3) ... 192 See page 73. Dimethyl-aniline, . C6H5.N(CH3)o 0-5 192 See page 74. Ethyl-aniline, . C8H5.NH(C2H5) ... 204 See page 73. Diphenylamine, CeHg-NHCCeHs) 54 302 See page 79. Acetanilide, . C6H5.NH(C2n30) 112 295 See page 68. Acetotoluide ^^^^ho- [ C6H4(CH3).NH(C2H30)| 65-66 147 302-304 300-307 (Produced by action of •< heat on toluidine ( acetate. Nitranilines, . C6H4(N02).NH2. ... ... From imperfect reduc- tion of dinitroben- zene. Paraniline, C12H14N2 192 330 Xenylamine, . C,2H9.NH2 45 322 ... Phenylene - diamine (para-), . C6H4:(NH2)2 C3 287 Reduction of dinitro- benzene (page 87). Toluylene-diamine (para-), . C6n3(CIl3):(NH2)2 99 283-285 See page 88. Azobenzene, . C6H5.N2.C6H5 65 293 Imperfect reduction of nitrobenzene. Nitrobenzene, . C6H5.(N02) 3 210 Vol. II. page 476. ( ortho- ^C6H4(N02)2 i 118 Monoclinic tables. Dinitro- J meta- benzenesl 90 Long needles or thin rhombic tables. I para- 172 ... Monoclinic needles. ■^T.^.„^ ( ortho- i ( below -20 "223 Sp. gr. 1-163 at 23°-5. |.C6H4(CH3XN02) 1 16 54 230 238 Sp. gr. 1-168 at 22°. Benzene, . CeHs 5-5 80-5 Vol. II. page 469. Toluene, . C6H6(CH3) below -20 111 Vol. II. page 479. Amidothiophene, . C4H3S.NH2 ... ... ... Paraffins, . i CaHan+a ... Especially in aniline oils derived from cannel-tar benzols. The assay of aniline oils is usually limited to observations of the colour, odour, and specific gravity, supplemented by a careful frac- tional distillation and tests for water, nitrobenzene, hydrocarbons, &c. The specific gravity of aniline oil is a valuable indication of its composition. The observation must be made by the plummet or specific-gravity bottle at exactly 15° C, and the result referred to water at the same temperature taken as unity.^ ip. Schoop {Chem. ZeiL, ix. 178 ; Jour. Soc. Chem. Ind., v. 178) gives the density of pure aniline as 1*0377 at 1° C; orthotoluidine as 1*0143; and paratoluidine as 1 '0045 at the same temperature ; the coefficient of expansion being in each case 0*00081 for 1° C. 64 EXAMINATION OF ANILINE OILS. The following figures represent the densities as thus observed : — Specific gravity at 15° C. Pure aniline, . . . . TO 2 6 8. Aniline oil for red, . . . 1*0075 to 1-0012. Orthotoluidine, .... I'OOST. Mixture of equal parts of ortho- \ .0075 and para-toluidine, . . J Paratoluidine, .... Solid. The odour of pure aniline is very different from that of the toluidines. The presence of toluidine in aniline is indicated by the density of the sample, its diminished solubility in dilute alcohol (page 65), and by the results of the fractional distillation (page 65). In addition to these characters, the following tests are sometimes of service : — Pure aniline affords no rosaniline on treatment with oxidising agents, but if toluidine be present magenta is readily formed. The test is best made by mixing 5 c.c. of the sample of aniline with an equal measure of a concentrated solution of arsenic acid, containing about 75 per cent, of AsgOg and having a density of 2 '04. The mixture, contained in a small flask or long test-tube, is immersed ill a paraffin-bath heated to 180° C. The mixture rapidly changes in colour, and swells considerably. When the action is complete, the contents of the tube acquire a metallic bronze appearance and no longer intumesce. The product is treated with boiling water, when, if the sample contained toluidine, arseniate of rosaniline dissolves and communicates an intense crimson colour to the liquid. Neither pure aniline nor toluidine alone gives this reaction. If a sample of commercial aniline be mixed with some solid magenta and a few drops of glacial acetic acid, and the whole heated to 180° C, as described above, ammonia is abundantly evolved, and in a short time the mixture becomes intensely blue from the formation of trip h enyl-ros anil in e. With pure aniline the blue is very pure in shade, but when toluidine or xyli- dine is treated in a similar manner the product is intensely purple, and a mixture of the bases gives proportionate intermediate shades of colour. If a little of the " melt " be withdrawn from the tube, diluted considerably with alcohol, a few drops of acetic acid added, and then streaked on white filter-paper by means of a glass rod, the purple tint is readily observed, especially if the paper be held up before a gas-flame. A valuable indication of the general composition of an aniline oil is obtained by submitting the sample to fractional distillation, and noting the proportions of distillate obtained at various tem- ASSAY OF ANILINE OILS. 65 peratiires. The distillate may be measured after each rise of 5 degrees in the boiling-point of the sample, or the temperature may be observed when each consecutive 5 or 10 per cent, fraction has passed over. The latter is the plan now commonly adopted, 100 c.c. of the sample being employed, and the arrangement of the apparatus being exactly the same as in the fractional distillation of benzols (Vol. II. page 495). The heat is applied cautiously at first, in order to dissipate any water. ^^Tien this is effected, which will be known by the rapid rise of the thermometer, the heat is so regulated that the distillate shall fall in distinct drops, about sixty per minute. With each increase of 10 c.c. in the volume of the distillate the temperature indicated by the thermometer is observed and recorded, the process being continued till 90 or 95 c.c. have passed over. A very simple test for aniline oils was devised and communicated to the writer by the late B. Nickels, who found it to give useful results, and to indicate differences between samples not readily distinguishable by the ordinary fractional distillation process. The test is based on the greater solubility in dilute alcohol of aniline as compared with toluidine and xylidine, and is thus performed : — 6 c.c. measure of the sample is taken with a pipette and diluted to 40 c.c. with methylated spirit. Distilled water is then gradually added from a burette, with constant shaking, till a permanent tur- bidity is produced, when the volume of water employed is noted. Operating in this way, a sample of very pure aniline required 126 c.c. of water to produce permanent turbidity. The following figures, obtained by B. Nickels in 1881, show the results yielded by three typical specimens of commercial aniline as then manufactured : — A. B. C. Pure Aniline. Heavy Aniline. Toluidine. Colour, Pale amber. Amber. Deep brown. Specific gravity at 15°-5 C, . 1-025 1-011 1-002 Water required for precipitation, 106-4 C.C. 73-7 C.C. 63-2 c.c. •c. •c. •c. 10 per cent, distilled over at 183i 189 195 20 „ „ ,, . . 183i 1891 1951 SO .. „ „ . . 1831 190 196 40 „ „ „ . . 184 191 196^ 50 „ „ „ . . 184i 191J 197 60 „ „ „ . . 184 192i 197i 70 „ „ „ . . 184 193 198 80 „ , . . 184 1941 198i 90 „ ., „ . . lai 197 1991 95 „ „ „ . . 201 Sample A was a fair commercial specimen of the quality known "pure aniline," and actually contained some 95 per cent Vr»T. TIT "DA 1301 TT IT as "p VOL. III. PART II. 66 DISTILLATION OF ANILINE OILS. of real aniline. An article of this high purity is required for the manufacture of aniline blue, triphenyl-rosaniline (see page 64), any notable admixture of toluidine resulting in a pro- duct dyeing with reddish tinge.^ The quality known as "heavy aniline," exemplified by B, is a fair sample of aniline oil for red (see page 62). This class of aniline is produced from benzols containing a considerable proportion of toluene, and the aniline oil itself is a mixture of aniline and toluidines. Good samples of aniline oil for red contain from 35 to 42 per cent, of real aniline, 35 to 50 per cent, of ortho toluidine, and 14 to 24 per cent, of paratoluidine. K. J. Friswell thinks 100 c.c. an undesirably small quantity for fractional distillation. He prefers to operate on 250 c.c, which he distils in a flask with a side-tubulure, and he recommends an observation of the temperature at which the last drop disappears from the bottom of the flask. A naked flame is used, and a few fragments of platinum wire or fire-brick added to the contents of the flask. The following figures were obtained by Friswell (Thorpe's Diet. Applied CJiem.y i. 165) by the examination of commercially pure aniline. No. 1. No. 2. No. 3. 1 Specific gravity at 15' C, . . . . 10 per cent, over at, 20 „ „ 30 „ „ S ;: ;;:::::: fo :; :; :;:•:: 80 „ „ 90 „ „ Dry at, 1-02710 °C. 184-7 184-7 184-7 184-7 184-8 184-9 185-0 185-1 185-1 186-7 l-02«84 °C. 184-6 184-8 184-8 184-8 184-8 184-8 184-8 184-8 184-8 186-8 1-02690 "C. 184 6 184-6 184-7 184-7 184-8 184-8 184-9 184-9 185-0 Any neater present in aniline oil will be found in the very first portions (first fraction of 10 per cent.) whenever the sample is submitted to distillation. It takes the form of globules, which are not miscible with the next fraction of the distillate nor with petroleum spirit. Water may exist in aniline in any proportion from a trace up to 3 or 4 per cent., but a good commercial recti- fied specimen should not contain more than 0'5 per cent. Aniline is readily soluble in a strong aqueous solution of aniline hydro- ^ In good samples the boiling-points hold closely together, differing by one or two degrees only. Insqualities or jumps in the boiling-point, especially at the beginning and end of the distillation, indicate badly-made samples oi mixtures. IMPURITIES IN ANILINE OILS. 67 chloride. A solution of the kind, of 1"08 specific gravity, is stated by Watson Smith to be sometimes sold as aniline oil, which in colour and taste it closely resembles. Such a fraud would be at once detected on distillation. Benzene, toluene, and other hydrocarbons will separate when the first fraction of 10 per cent. (10 c.c.) is treated with an equal volnme or slight excess of hydrochloric acid, and water added to 100 or 150 c.c. They assume the form of oily globules which float even on diluting the liquid. The best samples of pure aniline show only a slight opalescence when thus treated, but the smell of the " light stuff " (Vol. II. page 488) is always perceptible. In recovered anilines these impurities exist to a notable extent, since they sur- vive the reactions by which the bases are consumed. Aniline for red usually contains somewhat more hydrocarbons than pure aniline. Nitrobenzene and nitrotoluene may be recognised, even when mere traces are present, by the milky appearance of the liquid produced by saturating 1 c.c. of the original sample of oil with hydrochloric acid. On diluting the liquid with water, and leaving it at rest for some hours, any considerable quantity of nitrobenzene will collect at the bottom in the form of oily globules, which, after separating the acid liquid, may be identified by the smell and other char- acters. Still smaller quantities of nitrobenzene may be recognised if the " tailings" be operated upon, instead of the original sample. Nitrobenzene occurs more frequently in magenta-aniline and tolui- dine than in the oils of lower boiling-point. Nitrobenzene is also indicated by the yellow colour of the froth produced when the sample is violently agitated. Acetanilide and acetotoluide were impurities characteristic of aniline prepared by the reduction of nitrobenzene with acetic acid and iron, but are now rarely met with in aniline oils. In any case they would become concentrated in the " tailings," together with phenylene-diamine, azobenzene, paraniline, " xenylamine," &c. Aniline tailings is the name applied to the least volatile portion of aniline oils. They contain little or no aniline ; some toluidine, xylidine and cumidine ; nitrobenzene and its homologues ; and some or all of the bye-products tabulated on page 63 which boil above 200° C. The composition and special methods of examination of com- mercial toluidine are described on page 54 e^ seq. Anilides. The anilides are derivatives of aniline in which one or both of the hydrogen-atoms of the amido-group are replaced by acid- 68 ANILIDES. radicals. The homologues of aniline yield similar derivatives (e.^., aceto-toluide, page 52). The most important and typical mem- ber of the class isacetanilide or phenylacetamide : — C,H,.NH(C,H30); or C^H^O.NHCC.H,) . A number of derivatives of acetanilide have been prepared, and certain of them have found some employment as analgesics and antipyretics, as for instance : — Acetanilide. Phenylacetamide. Antifebrin. CgH5.NH(C2H30). Bromacetanilide. Antiseptin. Bromi- ) ^ ^^ ^j ^.^ ^ ^. nated antifebrin. (Page 71.) f ^HBr.N4H(C2H30). Methylacetanilide. Exalgin_ Methy- j c,H,.N(CH3)(C,H30). lated antifebrin. (Page 71.) j 6 5 \ 3/v 2 3 / Aceto-amidophenol. Hydroxy-antifebrin, CgH4(OH).NH(C2H30). Aceto-anisidine. Methacetin. ) p -rr /n nir \ Arw/r" tt r\\ Methoxy-antifebrin. (Page85.) / ^^.(O.CHg^NHCC^HgO). Acet-phenethidine. Phenacetin. | n tt /r\n tt \ attt/z-i tt rw Ethoxy-antifebrin. (Page 81.) | ^e^^iO.C.U.yiSliiC.'Kfi). Amido-phenacetin. Phenocoll. C6H4(O.C2H5).NH(C2H20.NH2), Most of these bodies are described in the following pages. The relationship of antifebrin to hypnone, hydracetin (pyrodine), and phenyl-urethane, is shown by the following formulae : — Acetophenone. Hypnone (Part I. page 23). CgH5.(CO.CH3). Acetanilide. Antifebrin (see below). C6H5.NH.(CO.CH3). "^Tpl^e'Ts )^'^'''''''' ^^^"^""^^' \ CA.NH.NH.(C0.CH3). "^ThS^^^^^ ^^'"l CgH,NH.NH.(C,HA). Phenyl-urethane. Euphorin. (Page 72.) C6H5.NH.(CO.O.C2H5). Acetanilide. Phenylacetamide. CgH5.NH(C2H30). This substance was originally obtained by the action of acetyl chloride on aniline. It is more conveniently prepared by boiling aniline with glacial acetic acid for many hours under an inverted condenser, until the product solidifies on cooling. The mass is then melted and poured into water, to remove unconverted aniline and acetic acid. It may be purified by distillation and crystal- lisation from alcohol, benzene, or hot water, from which it separates in colourless unctuous laminae, resembling boric acid, soluble in about 190 parts of cold or 18 of boiling water. Acetanilide is odourless, but produces a slight burning sensation on the tongue. It occurs commercially as a crystalline powder or scales. It melts at 112°-113°, and distils unchanged at 295° C. Acetanilide ACETANILIDE. 69 dissolves in 3| parts of alcohol, and is very soluble in ether, chloroform, and benzene, yielding neutral solutions. Acetanilide is a weak base. The hydrochloride is obtained by passing hydrochloric acid gas through a solution of acetanilide in acetone. It forms needles which are decomposed into their con- stituents by water, and gradually converted into acetic acid and aniline hydrochloride on exposure to moist air. Acetanilide dissolves in strong sulphuric acid without change of colour. On treating the solution with nitric acid, the acetanilide is converted chiefly into ^am-nitroacetani 1 ide (page 50), some of the ortho-Q.om^o\mdi and, in presence of a large excess of sulphuric acid, a little of the meto-compound being also formed. Nitrous acid, passed into its acetic acid solution, converts acetani- lide into an unstable nitrosamine, C6H5.]S'(C3H30)(NO). When heated with zinc chloride to about 250°, acetanilide yields flavaniline, C^gHi^NgjIICl (Part I. page 245). Treated in alcoholic solution with sodium ethylate, acetanilide yields a sodium derivative, CgHg.NNaCgHgO, but when this is boiled with water it splits into aniline and sodium acetate. Acetanilide behaves like aniline on treatment with caustic alkali and chloro- form (page 46), and the formation of the disagreeably smelling isonitrile is a delicate reaction for its presence (compare page 83). Acetanilide behaves like aniline when treated with phenol and solution of bleaching powder (page 45). When treated with a solution of potassium chlorate in strong sulphuric acid, acetanilide gives a red coloration, changed to yellow on dilution. With a crystal of a nitrite and a drop of concentrated hydrochloric acid it produces a yellow colour, changing on heating to green and blue ; and, on evaporating the liquid to dryness, an orange residue is obtained, changed to red on adding ammonia (Vitali). When acetanilide is heated gently with mercurous nitrate, a body is produced which dissolves in alcohol with green colour (Y V n). If a few centigrammes of acetanilide be gently heated with two or three drops of a solution of mercurous nitrate, and when solution has been effected two or three drops of sulphuric acid added, a blood-red coloration will be produced (C e 1 1 a and A r z e n o). The same reaction is produced by phenol, resorcinol, thymol, and salicylic, gallic, and tannic acids, but not by benzoic acid. Acetanilide gives no colour-reactions with ferric chloride, nitrites in very dilute solutions, or potassium bichromate in aqueous solu- tion. These reactions distinguish it from antipyrine and kairine. Various other colour-reactions of acetanilide have been described. 70 ASSAY OF ACETANILIDE. As a rule, the most satisfactory method for its positive identifica- tion is to heat the substance with alcoholic potash^ dilute with water, and shake with ether. The ethereal layer is examined for aniline, while the aqueous liquid is tested for an acetate. To detect acetanilide in urine, V u 1 p i u s boils the liquid with hydrochloric acid, cools, extracts with ether, and tests the ethereal solution with phenol and bleaching powder solution. E. Ritsert {Pharm. Zeit., xxxv. 306; Jour. Cliem. Soc, Iviii. 1349) gives the following tests for the purity of commercial acet- anilide : — The sample should leave no ash on ignition, and after drying for two hours at 105°, should melt at 114°. A higher or lower melting-point indicates the presence of aceto-toluides. 0"1 gramme dissolves in 1 c.c. of strong hydrochloric acid to a clear solution , which, after a few minutes, precipitates acetanilide hydro- chloride (methyl-acetanilide does not yield a similar reaction). No change should be produced on adding a drop of nitric acid, which, after a time, produces a yellow or brown coloration if j^hen- acetin or methacetin be present. If 0*1 gramme be boiled in por- tions in 2 c.c. of strong hydrochloric acid, the solution cooled, and a drop or two of chlorine water added, a fine blue coloration is produced. The aqueous solution of acetanilide should be free from acid reaction (indicating acetic acid). On boiling it and adding ferric chloride, a deep reddish-brown colour should be produced, destroyed by a mineral acid. If a drop of dilute solution of potassium' permanganate (1 : 1000) be added to a boiling aqueous solution of 1 gramme of acetanilide in 30 c.c. of water, the pink coloration at first produced should persist at least five minutes, and should not change to yellow on again boiling. . Precipitation at this stage indicates the presence of free aniline, resinous products, aceto-toluides, or other impurities. In the additions (1890) to the British Pharmacopoeia, acetani- lide is described as melting at 235° F. ( = 112°-8 C), and dis- solving in sulphuric acid without coloration. The solution in 18 parts of boiling water should be clear, neutral, and odourless ; and after cooling should not be coloured on adding ferric chloride. This is directly opposed to the experience of Ritsert above quoted. In the German Pharmacopoeia the direction is to add ferric chloride to a cold saturated solution, thus avoiding the dissociation and formation of acetic acid liable to occur on boiling. According to the German Pharm^acopoeia, on heating with caustic alkali solution, acetanilide gives off an aromatic vapour, which, after addition of a drop of chloroform and renewed application of heat, is changed to the disagreeable smell of the isonitrile. Further, O'l gramme of acetanilide should yield a clear solution when boiled with 1 c.c. of ANTIFEBKIN — EXALGIN. 71 hydrochloric acid for one minute ; and, after adding to the liquid 2 c.c. of carbolic acid, a cloudy red coloration should be produced by solution of bleaching powder, changed to a permanent indigo- blue (i n d o p h e n 1) on adding excess of ammonia. Acetanilide has i)owerful antipyretic properties, and has received an extensive application in medicine under the name of "anti- f e b r i n,"^ though dangerous symptoms are sometimes produced by it {Pharm. Jour., [3], xx. 1059). The dose is from 3 to 10 grains. According to S a 1 z e r, commercial antifebrin is liable to certain unchanged aniline, which may be detected by dissolving the sample in cold hydrochloric acid, and pouring on the liquid a solution of bleaching powder. Pure acetanilide yields a white precipitate, which dissolves on shaking the liquid, but after a time coloiirless silky needles separate. In presence of aniline the well-known violet coloration is produced. Acetanilide has been used as an adulterant of antipyrine (page 36). The melting-points of the pure substances are nearly iden- tical, but a mixture of equal proportions of the two melts at 45° C. Of the three isomeric aceto-toluides (page 52), only the meta- compound possesses antipyretic properties. Para-brom-acetanilide, CQH.fiT.'NJI(CO.Cli^), has been intro- duced as a remedy under the name of " a n t i s e p s i n." It forms small pearly prisms, melting at 164°*5, and devoid of taste or smell. It is soluble with difficulty in cold, but readily in hot water, as also in alcohol and ether. Acet-methylanilide or Methyl-acetaniUde, CgHg.N(CH3)(C2H30), is prepared by warming together methylaniline and acetyl chloride. The product is boiled with water, when the new body crystallises on cooling. Methylacetanilide has been introduced as an anti- rheumatic and analgesic under the name of " e x a 1 g i n." In doses ^ When administered to rabbits, acetanilide is oxidised to para-amidophenol, C6H4(OH).NH2, with complete elimination of the acetyl-grouj). In dogs there is a small formation of para-aniidophenol, but the chief change consists in a simultaneous oxidation of the aniline-residue to ortho-amidophenol, of the acetyl-group to carboxyl, and in the formntion of carbonyl-ortho- hydroxyamidophenol, C6H3(0H)-{ q |- CO , the anhydride of which is excreted in the urine as a sulphate. In both the rabbit and the dog the amido-phenols are also eliminated as sulphates. In man, the acetyl-group is not wholly oxidised, the urine containing the sulphate of aceto-par- a m i d p h e n o 1. In all cases there is an oxidation of one of the hydrogen atoms of the benzene-nucleus to hydroxyl, while the proportion of ethereal sulphates is increased (compare "Aniline," page 46), the urine is red from excess of bilirubin, reduces alkaline cupric solution, and is strongly laevo- rotatory ; the optically active body probably being the above-mentioned sulphate (Gressly and Nencki, Monatsh., xi. 253). 72 EXALGIN. BENZANILIDE. of J to 4 grains its effects are said to be very satisfactory. Exalgin forms fine needles or large white tablets (compare "Acetanilide"). It melts at 100°-101°, boils without decomposition between 240° and 250°, and is slightly soluble in cold water, but more so in boiling, and very soluble in water containing a little alcohol. It is saponified with difficulty by caustic alkali, but completely by concentrated hydrochloric acid, with formation of acetic acid and methylaniline. Hirschsohn states that exalgin may be distinguished from antifebrin and phenacetin by treating 1 gramme with 2 c.c. of chloroform, which dissolves the exalgin only. A chloroformic solution of exalgin remains clear on adding ten measures of petroleum ether, whereas the solutions of antifebrin and phenacetin become turbid. 20 per cent, of acetanilide, or 10 of phenacetin, may be detected in exalgin by these reactions. An aqueous solution of antifebrin gives a bromo-derivative on adding bromine-water, thus differing from exalgin and phenacetin.^ Benzanilide, CgH^.NH(C0.CgH5), is obtained by the action of benzoyl chloride on aniline, or by boiling together equivalent quantities of benzoic acid and aniline. It forms a white, crystalline powder, melting at 160°-161° and volatile without decomposition. It is almost insoluble in water, but dissolves in fifty-eight parts of cold, or seven of boiling, alcohol, crystallising on cooling in nacreous plates. It is difficultly soluble in ether. Benzanilide is not attacked by aqueous alkalies or acids, but is saponified by fusion with caustic potash. It has been found valuable as an antipyretic for children, in doses of 2 to 8 grains, and is said not to produce objectionable secondary effects. Phenyl-urethane. Ethyl Carbanilate. CgHg.NHfCO.OCgHg). This compound has recently acquired a practical interest owing to its introduction as a synthetic remedy under the name of " e u p h r i n." It is produced by the reaction of aniline on ethyl- chlorocarbonate, and occurs as a white crystalline powder, of a faintly aromatic odour and scarcely perceptible taste, which subsequently be- comes acrid and clove-like. It melts at 49° to 51°, boils at 237°, and is only slightly soluble in cold water, but very freely soluble in alcohol, and sufficiently soluble in sherry and other alcoholic liquids to be conveniently given in solution in such menstrua. According ^ Exalgin may also be distinguished from antifebrin, methacetin, and phen- acetin by treating 2 grains (or 0*1 gramme) with 20 minims (or 1 c.c.) of concentrated hydrochloric acid. Phenacetin remains insoluble. Antifebrin dissolves, but separates again in crystals of the hydrochloride. Methacetin also dissolves, but is recognised by the reddish-brown coloration produced on adding one drop of nitric acid. SUBSTITUTED ANILINES. 73 toSansoni, after administration of phenyl- ure thane, the urine shows the para-amidophenol reaction either directly or after dis- tillation with potassium carbonate. The proportion of urea is increased, but the urine is free from phenol, aniline, albumin, and sugar. Substituted or Alkylated Anilines. These bases result from the replacement of one or both of the hydrogen atoms of the amido-group of aniline by alkyl or other basylous radicals. The bases of this class are obtained by heating the hydro- chloride or other salt of aniline (or its homologues) with the alcohol with which it is intended to react, or the halogen salt of this alcohol with free aniline. The only substituted anilines which require special description are the following : — Formula. Specific Gravity. 1 Boiling- Point: Reference. Methyl-aniline, . . . Dimethyl-aniline, . . Ethyl-aniline, .... Diethyl-aniline, . . . Phenyl-aniline (Diphenylaraine), . Diphenyl-auiline (Triphenylamine), . C6H5.NH(CH3) r6H5.N(CH3)2 CeHg.NHCCsHg) C6H5.N(C2H5)2 CeHg-NHCCeHe) C6H5.N(C6H6)2 •976 at 15* •9553 at 15' •954 at 18° •937 at 13° 1161 192 192 204 213 ^5 302 Page 73. Page 74. Page 79. Page 79. Page 80. Diphenylamine is a very weak base, and in triphenylamine the basic character is entirely lost. Methyl-aniline. CgH5.NH(CH3). This base is obtained by the action of iodide, nitrate, or chloride of methyl on aniline, or by heating methyl alcohol with aniline hydrochloride.^ In all cases dimethyl-aniline is formed simultane- ously, and hence in the production of mono-methylaniline a portion of the aniline remains, in practice, unattacked.^ ^ Pure methylaniline may be obtained by the reaction of methyl iodide ot sodium acetanilide, C6H5.NNa(C2H30), and saponification of the re- sultant compound l>y caustic alkali. ^ To separate this from its mono- and di-methyl-derivatives, dilute sulphuric acid is added as long as aniline sulphate continues to separate. The sulphuric acid solution is separated from the solid aniline sulphate by pressure in a linen cloth, and the expressed liquid treated with caustic soda. The substance which separates is dried and treated with acetyl chloride until no further rise of temperature is observed, when the product is poured into cold water. On cooling, methyl-acetanilide, C6H5.N(CH3)(C.^H30), separates in long needles, while dimethylaniline hydrochloride remains in solution. 74 METHYL-ANILINE. Methylaniline is a liquid boiling at 192"*. It resembles aniline, but is ligliter than water, and its odour is stronger and more aromatic. The sulphate is soluble in ether and uncrystallisable. A solution of bleaching powder first colours it violet and then brown. The conversion of methylaniline into toluidine is re- ferred to on page 41. Methf/IaniUne-nitrosamine, CgH5.N(CH3)(NO), separates as a yellow oil on treating a cold solution of methylaniline hydro- chloride with sodium nitrite, while any aniline and dimethyl- aniline are converted into soluble products. If the nitrosamine be extracted by ether, and treated with tin and hydrochloric acid, it is reduced to methylaniline, which may thus be obtained in a pure state (compare page 7). The nitrosamine is destitute of basic properties. It has an aromatic odour, and may be distilled in a current of steam, but not alone. When methyl- aniline-nitrosamine is warmed with phenol and sulphuric acid, the mixture diluted with water and saturated with caustic alkali, it yields the intense green-blue coloration produced by all nitrosamines (L i e b e r m a n n's reaction). When heated with alcoholic hydrochloric acid it undergoes molecular transformation into para nitroso- methylaniline, CgH4(N"0).NH(CH3), a body crystallises in green-plates or steel-blue prisms, and other- wise resembling paranitroso-dimethylaniline (page 75). Dimethyl-aniline. CgH5.N(CH3)2. This important base is obtained by the action of excess of methyl iodide on aniline. On the large scale, methyl iodide was formerly employed, but was afterwards replaced by the nitrate, and this again (owing to its explosive properties) was superseded by the very volatile methyl chloride. The product obtained in this way contained about 5 per cent, of monomethyl-aniline, but no other admixtures. Dimethylaniline is now always manufactured by heating together a mixture of aniline hydrochloride, aniline, and methyl alcohol.^ The methyl alcohol employed must be quite The former product is saponified by boiling with dilute hydrochloric acid, which converts it into acetic acid and methyl-aniline hydrochloride. Another method of separating aniline from its mono- and di-methyl-derivatives is referred to in the footnote on page 76. Methyl-aniline can be re-formed by treating its nitroso-derivatives with tin and hydrochloric acid. ^ The aniline must be free from toluidine and impurities insoluble iu hj'drochloric acid ; and the methyl alcohol employed must be quite fiee from ethyl alcohol and acetone, the latter of which not only reduces tlie yield, but gives a product unsuitable for the preparation either of methyl violet or malachite green, owing to the formation of a base of the formula CH2(CeH4.N(CH3)2)2. 93 parts of aniline are used, of which 18 are saturated DIMETHYL-ANILINE. 76 free from etliyl alcohol and acetone, the latter of which not only reduces the yield, but gives a product unsuitable for the prepara- tion either of methyl-violet or malachite-green, owing to the forma- tion of a base of the formula : — CH2(CgH4.N(CH3)2)2. Dimethylaniline is a colourless oily liquid, solidifying at 0°"5 and boiling at 192°. It has a sharp basic odour, and forms uncrystallisable salts. It unites with methyl iodide, with energy at the ordinary temperature, to form the iodide of trimethyl- phenylammonium, which breaks up again into its constituents on distillation, but by reaction with argentic oxide yields tri- methyl-phenyl-ammonium hydroxide, MegPhN.OH, a crystalline, very deliquescent, corrosive, and very bitter base. With bleaching-powder solution, dimethylaniline merely gives a pale yellow coloration, a reaction by which any contamination by aniline or mono-methylaniline can be detected, as these bases give a violet colour with the same reagent (page 45). Mild oxidising agents, such as chloranile, carbon oxychloride, and cupric chloride, convert the methylaniline into methyl violet (Part I. page 234). With acid chlorides and aldehydes, it yields complex compounds. Thus with benzaldehyde it gives tetra- methyl-paradiamido-triphenylmethane, and the corresponding hydroxide or carbinol, CgH5.[N(CH3)2]2.0H, obtained from this by oxidation, is the base of malachite or benz- aldehyde green (Part I. page 241). By reaction with diazobenzene chloride, dimethylaniline is converted into dim e th y 1-amid o- azobenzene, CgH5.N2.CeH4.N(CH3)2, or butter yellow; while with diazobenzene-sulphonic acid it yields helianihin or methyl-orange (Part I. page 188). Paranitroso-dimethylaniline, C^J^0).^{(yR^2^ is produced by the action of nitrite of sodium or nitrite of amyl on dimethyl- aniline.^ It is manufactured on a large scale for the production with hydrochloric acid and 75 parts of methyl alcohol. The excess of methyl alcohol, and comparatively small quantity of hydrochloric acid, tend to produce a purer oil. With more hydrochloric acid, the reaction takes place at a lower temperature, but there is a danger of forming toluidine. The mixture is lieated at first to a temperature of 270°, at a pressure not exceeding 27 atmospheres. When the reaction is complete, in about 15 hours, the pressure decreases without the temperature being reduced (Schoop, Chem. Zeit., xi. 253 ; Jour. Soc. Chem. Ind., vi. 436). ^ Ten parts of dimethyl-aniline are dissolved in 50 of strong hydrochloric acid and 200 of water, and to the cold solution is gradually added a solution of 5*7 parts of sodium nitrite in 200 of water, when the hydrochloride of the nitroso-compound is obtained as a body crystallising in yellow needles, from which the free base is obtained by treatment with potassium carbonate and solution in ether. 76 NITROSO-DIMETHYL-ANILINE. of methylene-blue, indophenol, and toluylme-red (Part I. pages 258, 285). It crystallises in large green plates or tables, soluble in ether. By oxidation with potassium permanganate or ferri- cyanide, it is converted into paranitro-dimethylaniline, CgH4(N02).N(CH3)2, which forms long, sulphur-yellow needles, melting at 162°-163°. When boiled with caustic alkali, nitroso- dimethylaniline is completely split up into dimethylamine, H.N(CH3)2 (which may, by this reaction, readily be obtained pure), and nitrosophenol or quinonoxime, CgH^O(NOH) (Part I. page 157). Commercial Dimetliylaniline usually contains more or less aniline and monomethyl-aniline. By the entrance of methyl into the benzene-nucleus, more or less dimethyl- 1 1 u i d i n e, CgH4(CH3). N(CH3)2, and higher homologues are usually present in addition. Hence the dimetliylaniline of com- merce usually boils between 198° and 205°. The smaller the range in the boiling-point the better the sample. The presence of aniline and monomethyl-aniline is indicated by the rise of temperature produced on treating 5 c.c. of the dry oil with an equal measure of acetic anhydride. This is stated to be 0°'815 C. for each unit per cent, of monomethylamine present. For small percentages this appears to be fairly correct, but with a product actually containing 30 per cent., an excess of over 7 per cent, is said to be indicated. A serious objection to the method is that it wholly fails in presence of aniline. But the presence of aniline can be recognised by mixing a few drops of the oil with a few drops of ether, and adding one drop of strong sulphuric acid, when, if aniline be present, its sulphate will separate as a white precipitate. A more plausible method is that of Nolting and B o a s s o n {Ber., X. 795), based on the different behaviour of the bases with nitrous acid,^ but the results yielded in practice have been found ^ When aniline hydrochloride is treated in cold solution with sodium nitrite, it yields diazobenzene chloride, while dimetliylaniline is converted into the hydrochloride of its nitroso-derivative (pap:e 75). Both these bodies are freely soluble in water, while monomethyl-aniline is converted by the same treatment into the non-basic methylaniline-nitrosamine, which can be extracted by agitating the liquid with ether. If this reaction occurred in its simplicity, the monomethyl-aniline could be estimated from the weight of the nitrosamine left on evaporating the ethereal solution. But when this is distilled in a current of steam, in which the nitrosamine is vola- tile, a considerable quantity of nitrophenyl-methylnitrosamine, C6H4(N02).N(NO)(CH3), remains as a residue. This body is clearly produced by the oxidation of the nitrosamine, and direct experiment shows that pure monomethyl-aniline, on treatment with excess of nitrous acid, is converted ASSAY OF DIMETUVL- ANILINE. 77 unreliable by R e v e r d i n and de la Harpe. These chemists recommend {Cliem. Zeit., xiii. 387, 407 ; Jour. Soc. Chem. Ind.^ viii. 84), for the estimation of thrj aniline and methyl-aniline con- jointly, acetylisation of the bases, and estimation of the excess of acetic anhydride by titration with alkali ; and for the estimation of the aniline, diazotising and treating the product with beta-naphthol disulphonic acid. At ordinary temperatures acetic anhydride has no action on dimethylaniline, but on prolonged heating tetramethyl- diamido-phenylmethaneis formed in considerable quantity, if the reagent be in excess. Monomethyl-aniline is converted into methyl-acetanilide, CgH5.N(CH3)(C2H30), and aniline in the cold yields acetanilide, CgH^.NHCgHgO, but on heating more or less diacetanilide, CgH5.N(C2H30)2, is produced. To avoid the formation of these secondary products the following method of working is recommended : — From 1 to 2 grammes weight of the sample is mixed as rapidly as possible with an accur- ately known quantity (about twice its weight) of acetic anhydride, in a small flask fitted with a reflux condenser. After standing for half an hour at the ordinary temperature, 50 c.c. of water should be added, and the flask heated on the water-bath for fifty minutes to efl'ect the conversion of the excess of acetic anhydride into acetic acid. The liquid is then cooled, diluted to a known volume, and an aliquot part titrated with standard caustic alkali, using phenolphthalein as an indicator.^ By this means the excess of acetic anhydride, C^HgOg, is ascertained, and the diff'erence between the amount so found and that employed is the weight which has reacted with the aniline and methyl-aniline contained in the sample. 5 1 parts of acetic anhydride consumed in the reaction correspond to 107 of base in terms of methyl-aniline^ and the per- centage of base thus found (a) is calculated and recorded. The aniline itself is determined as follows : — From 7 to 8 grammes of the sample is dissolved in hydrochloric acid (28 to 30 c.c), and diluted with water to 100 c.c. 10 c.c. of this solution into it, to the exclusion of the simple nitrosamine. As the molecular weights of the two bodies are materially different (181 : 136), the indefinite character of the reaction prevents the accurate determination of the monomethylamine (Reverdin and de la Harpe, Chem. Zeit., xiii. 387, 407; Jour. Soc. Chem. Ind., viii. 84). 1 H. Giraud {Bull. Soc. Chim., 1889, ii. 142) modifies this process by employing the acetic anhydride dissolved in ten times its vohime of dimethyl- aniline. 10 c.c. of this solution is added to 1 gramme of the sample. After standing for one hour in a corked flask, water is added, and the liquid (boiled for some time and) titrated with standard baryta- water or phenolphthalein. 78 ASSAY OF DIMETHYL- ANILINE. is further diluted with water and cooled by ice. The solution is then diazotised by adding a solution of sodium nitrite in quantity suffi- cient to react with the whole of the sample if it consisted of aniline solely. A solution of the sodium salt of betanaphthol-disulphonic acid known as "Salt R" (Part I. page 194) is meanwhile prepared of a strength approximately corresponding to 10 grammes of naphthol per litre, and its precipitating power is calculated from its known strength, or exactly ascertained by experiment with pure aniline. A measured quantity of this solution is then treated with ex- cess of sodium carbonate, and to it the ice-cold solution of the diazotised sample is slowly added. Common salt is then added till a precipitate ceases to form, when the liquid is filtered, and portions of the filtrate are tested with salt R and the diazo- solution respectively, to ascertain which of these two is present in excess. Another experiment is then made with suitably varied volumes, until after a few trials exact precipitation of the colouring matter is attained without sensible excess of either the naphthol or diazo-solution. The reactions which occur are as follow : — C6H5.NH2,HCl4- HN02 = C6H5N : N.CI + 2H2O ; and C6H5.N2.CI + CioH,(OH)(S03Na)2 = HCl + CeH5.N2.CioH,(OH)(S03Na)2 . From these formulae, and the volumes of the two solutions required for exact reaction, the weight of aniline present can be calculated. 1 gramme of salt R will react with 0'2672 gramme of aniline. The percentage of aniline thus found {h) is multiplied by 1*15 ( = ^), which gives its equivalent in methyl-aniline, and this (c) subtracted from the sum of aniline and methyl-aniline in terms of methyl-aniline found by the acetylisation process {a) gives the per- centage of real methyl-aniline (d) present. The dimethyl-aniline is determined by difference. In the case of a sample of known composition. R e v e r d i n and de la Harpe obtained the following satisfactory results by the foregoing process : — Present. Found. Aniline, . . 10"42 per cent. 10 30 per cent. Monomethylaniline, 10*97 „ 11*16 „ Dimethylaniline (by difference), . 78*61 „ 78*54 100*00 „ 10000 „ The presence of monomethylaniline is more objectionable in dia- raethylaniline intended for the manufacture of green than in that to be used for violet. S c h p (Chem. Zeit.^ xi.. 254) states that DIPHENYLAMINE. 79 the proportion seldom exceeds 2 per cent., and that the best qualities of dimethylaniline are nearly 6r quite free from it. AYhen [)resent, monomethylaniline can be removed by shaking the oil with a small quantity of dilute sulphuric acid, or by boiling with acetic acid for two hours. DiETHYLANILINE. CeH5.N(C2H5)2. This base is best prepared by heating one molecule of aniline hydrobromide with 10 per cent, in excess of one molecule of ethyl alcohol to 145° for 8 or 10 hours. Nearly the theoretical yield is obtained. The base boils at 21 3°-5. Diethyl-orthotoluidine and diethyl-paratoluidine may be obtained by exactly similar means. DiPHENYLAMINE. PhENYLANILINE. C6H5.NH.C6H5. This base is obtained by heating aniline with the hydrochloride or other salt of aniline.^ Diphenylamine crystallises in small white plates, having an agreeable flowery odour and burning taste. It melts at 54°, and boils at 302° C. (Graebe). It is almost insoluble in water, but readily in alcohol, ether, benzene, and aniline. Diphenyl- amine has very feeble basic properties. The hydrochloride is a white crystalline powder, which turns blue in the air, and is decomposed by water. The most characteristic reaction of diphenylamine is the deep blue colour produced by adding a trace of nitric acid to its solution in strong sulphuric acid. The reaction, which is very delicate, is employed as a test for nitric acid. Commercial diphenylamine should be pale yellow, melt not much below 54°, be free from unpleasant odour and oily matters, and give no violet coloration with bleaching powder. It is used for making diphenylamine Uue, aurantia, and orange IV. Methijl-diphenylamine, CqR^.1<^(CR^)CqH^,^ boils at 282°, and gives various colour-reactions with oxidising agents. In dilute sul- phuric acid it dissolves to form a liquid of the colour of solution of potassium permanganate. ^ Six parts of aniline and 7 of anilino hydrochloride are heated to 250" untler a pressure of 4 or 5 atmospheres for 24 hours. The ammonia formed is allowed to escape at intervals to prevent reconversion of the diphenylamine into aniline. The product is treated with warm hydrochloric acid and a large quantity of water, which dissolves any unchanged aniline hydrochloride, and decomposes the hydrochloride of diphenylamine, which latter base separates out and is purified by distillation. ^ Made on a large scale by heating a mixture of 100 parts of diphenylamine, 68 of hydrochloric acid (sp. gr. 1"17), and 2 parts of methyl alcohol for 10 hours, to 200''-250'' at a pressure of 15 atmospheres. The product is treated with caustic soda, and the separated base distilled and shaken with twice its measure of strong hydrochloric acid. The hydrochloride of diphenylamine separates in the solid form, while that of the methyl-derivative forms a liquid, which is decomposed by adding a large quantity of water. 80 AMIDOPHENOLS. Warm nitric acid converts diphenylamine and its methyl- derivative into CgH2(N02)3.ISrH.C(.H2(N02)3 , hexanitro-di- phenylamine, the ammonium salt of which constitutes the colouring matter known as aurantia (Part I. page 156). Para-amidu-diphenylamine results from the reduction of phenyl- amido-azobenzene, nitro-phenylamine, or tropceoUn 00 (Part I. pages 181, 189, 190, 213). Triphenylamine. Diphenylaniline. (C6H5)3N. This body is formed by the action of bromobenzene on dipotas- sium aniline. It is a neutral body, melting at 127°, and crystallising from ether in nionoclinic pyramids. It forms no isonitrile, picrate, nor acetyl-compound, but yields iodide of triphenyl-m ethyl-am- monium on treatment with methyl iodide. Its solution in glacial acetic acid is coloured green on adding a little nitric acid, but with sulphuric acid it gives a violet coloration changing to blue. AmicLophenols. By the reduction of the nitrophenols, corresponding amido- compounds are obtained. These bodies may also be prepared by heating either of the three isomeric amido-hydroxybenzoic acids, C6H3(NH2)OH.COOII, with caustic baryta. In the amidophenols the acid character of the phenols is neutral- ised by the presence of the amido-groups, so that they only yield salts with acids ; but as phenols they are still capable of yielding alkyl-derivatives (e.p'., anisidine), while the hydrogen of their amido-groups may be replaced for acetyl, &c., as in phenacetin The amidophenols form colourless crystalline scales or plates, which are very readily oxidisable on exposure to air, with blackening and formation of resinous products, especially if impure. On the other hand, their hydrochlorides are relatively stable, and often capable of sublimation. The solution of para mid ophenol hydrochloride is coloured first violet and then green by solution of bleaching powder, quinone chlorimide, C6ll40(NCl), being formed ; while with chromic acid mixture, and other oxidising agents, it yields quinone, CgH^Og. Treat- ment with sulphuretted hydrogen and ferric chloride converts it into compounds of the methylene-hlue group (Part I, page 285). The formyl- and acetyl-derivatives of the amidophenols are converted with great facility into anhydro-bases. Thus e t h e n y 1- amidophenol, a basic liquid boiling at 200° to 201°, is obtained by boiling ortho-amidophenol with acetic anhydride. C6H,(OH).NHC2H30 = C^B./ ^C.CHg + Kfi. AMIDO-PHENOLS. 81 When this body is heated with dilute acids, the reverse action occurs, acetyl-orthoamidophenol being formed. The methyl esters of the amidophenols (anisidines or amido-anisols), and the corresponding ethyl esters (phenethi- dines or amidophenatols), are bases resembling aniline, and are employed for producing certain azo-dyes (e.g., anisol red, phenatol red; Part I. page 192). The acety 1-deri vati ves of these esters are used in medicine under the names of metacetin and phenacetin (see below). The following table shows the characters of the isomeric amido- phenols and their derivatives : — 1 OrtHO- 1 : 2 META- 1 : 3 PARA- 1 : 4 tl ii ft ii fi Amidophenol (page 80), 170 sub- limes. ... ... 184 ... Acetyl-derivative (page 80), ... ^6^nNH(COCH3) 201 ... ... ... 179 ... Methyl-ester (Anisidine) p „ rOCCHs) C6H4|nH2 •• 228 ... 251 56 246 Ethyl-ester (Phenethidine), .... 229 ... 180-205 (at 100 mm.) ... 253 Methacetin (page 85), . . . . C6^4{n*S(COCH3) 84 204 ... ... 127 ... Phenacetin (page 81), 70 97 ... 135 ... Amidophenacetin. Phenocoll (page 85), . C6H4{g^§?6)cH,NH,) ... ... ... ... 100-5 Phbnacbtins. ACET-PHBNBTHIDINBS. an. 1 1 occ^H,) ^*tNH(C0.CH3) The bodies of this formula have recently acquired some reputa- tion as antipyretics and analgesics. The phenacetins are prepared by ethylating the corresponding mono-nitrophenols, thus obtaining the isomers of the formula C6H^(N02).OC2H5. On treatment with zinc or iron and hydro- VOL. III. PAKT II. F 82 ACET-PHENETHIDINES. chloric acid, these are reduced to the corresponding phen- ethidines, CgH4(NH2).OC2H5, which are purified and acetylised by heating with glacial acetic acid for some hours, the products being recrytallised from water. Of the three isomeric phenacetins, the mefa-compound is unim- portant. It forms tasteless and odourless scales, melting at 96°. Para-acetphenethidine is the official variety in the German and British Pharmacopoeias (1890). It forms white, odourless, taste- less, glistening scaly crystals. It requires 1400 parts of cold, or 70 parts of boiling, water for solution, and is soluble to a notable extent in chloroform. Its solution in 1 6 parts of alcohol is precipi- tated by the smallest addition of water. The crystals melt at 135°. Ortho-acetphenethidine forms brilliant white, very light spangles, without taste or odour, and melting at 70° C. It is very slightly soluble in cold, but more readily in hot, water, separating again on cooling. It dissolves in about three parts of rectified spirit, and abundantly in chloroform. Besides the difi'erences in their melting-points and solubilities, para- and ortho-phenacetin are distinguished by their behaviour when boiled for several hours with dilute sulphuric acid (sp. gr. 1*26). When thus treated, the para- compound yields acetic acid and sparingly soluble sulphate of phenethidine. Orthophenacetin, on the other hand, is not decomposed by the same treatment, re- quiring the action of acid of 1*575 specific gravity for two hours at 90° to effect its saponification.^ If in either case the acid liquid be diazotised, and then treated with an ammoniacal solution of naphthol-disulphonic acid, a fine red-yellow colour will be obtained if paraphenacetin was employed, while with the ortho-compound a cherry-red coloration is produced. In either case the colouring matter may be precipitated by brine. This formation of an azo-colouring matter may be employed to detect the phenacetins in urine and other organic liquids. The urine is evaporated to dryness, and the residue treated with hot alcohol. The solution is filtered, evaporated, and the residue boiled for two hours with dilute sulphuric acid (sp. gr. 1'26) under a reflux condenser. The resultant solution is cooled to 5° or 6° C, treated with a 1 per cent, solution of sodium nitrite for five minutes, and then poured into a solution of napthol-disulphonic acid in excess of ammonia, taking care that the mixture remains ^ S. Liittke detects orthophenacetin by boiling 15 grammes of the sample with 25 grammes of dilute hydrochloric acid, when ortho-phenethidine hydro- chloride is formed, from which the free base may be separated by caustic soda, and its boiling-point (given by Liittke as 242° '5) determined. The hydro- chloride gives a blood-red coloration with ferric chloride. PHENACETIN. 83 alkaline. If either modification of phenacetin be present in the urine a characteristic coloration will be produced, from the intensity of which the amount of phenacetin may be estimated. For medicinal use, phenacetin is said to present considerable advantages over antipyrine, and especially over antifebrin (acet- anilide), for while the latter body is decomposed in the system with formation of aniline, which has marked toxic properties, phenacetin yields phenethidine, CqKJ^OC2'S.^).^'H.2, and amidophenol, CgH4(OH).N'H2, which are said to be harmless. Paraphenacetin, in doses ranging from 8 to 20 grains for adults, and from 2 to 3 grains for children, is said to be a valuable anti- pyretic and anti-neuralgic, without producing nausea, vomiting, cyanosis, or disagreeable after-effects. Being nearly insoluble, it is best given in the form of powders. The dose of orthophenacetin required to produce the same effect is larger than that of the para- compound, which is that of the British and German Pharma- copoeias. According to Renter {Fharm. Zeit., 1891, page 185) phena- cetin is liable to contain unconverted para-jphenethidine, which appears to be poisonous in very small doses, if taken for some time, producing nephritis and albuminuria. To detect the impurity. Renter melts 2 J grammes of chloral hydrate at 100°, and adds 0"5 gramme of the sample. On agitation the phenacetin dissolves, and, if pure, the solution will remain colourless when heated on the water-bath for five minutes, though after longer heating it will assume a rose tint. In presence of para-phenethidine, an intense coloration, ranging from red- violet to blue- violet, is produced in two or three minutes at most. S. Liittke detects diamidophenols or diamidoph&natols in phenacetin by grinding 0*5 gramme of bleaching powder to a fine paste with hydrochloric acid, and adding about 0"03 of the sample, when a red colour will be produced. The lower price of acetanilide, and its close physical resemblance to phenacetin, have suggested the possibility of the partial or com- plete substitution of the former body for the latter, and a flagrant instance of such a practice is actually on record {Fharm. Jour., [3], xxi. 377). The presence of 5 per cent, of acetanilide lowers the melting-point of the sample to 127°— 128°. H. Schwartz {Pharm. Jour., [3], xviii. 1085) recommends that 1 gramme of the suspected sample should be heated with 2 c.c. of caustic soda solution, a fragment of chloral hydrate or a few drops of chloroform added, and the mixture again gently heated. With phenacetin the odour is aromatic and not disagreeable, but in presence of acetanilide, the penetrating and repulsive smell of 84 PHENACETIN. phenyl-carbamine, CgHg.NC, is produced. On boiling the sample with caustic soda solution, oily drops of aniline separate if acetanilide be present in considerable quantity. If the cooled liquid, together with the separated globules, be shaken with ether, and the ether separated and evaporated, the residue when dissolved in water and treated with a drop of carbolic acid, and a clear solution of bleaching powder added, gives a blue-green coloration changed to onion-red by hydrochloric acid, and restored by ammonia. (See also Jour. Soc. Chem. Ind., vii. 772.) For the detection of acetanilide in phenacetin, M. J. Schroder recommends that 0'5 gramme of the sample should be boiled with 8 c.c. of water, and the liquid filtered when cold from the recrystal- lised phenacetin. The filtrate is boiled with a little potassium nitrite and dilute nitric acid, a solution of mercurous nitrate con- taining a little nitrous acid added, and the whole again boiled. A red colour will be obtained if the proportion of acetanilide in the sample exceeds 2 per cent. If 1 gramme of a mixture of equal parts of phenacetin with acetanilide be shaken with 200 c.c. of water, the whole of the acetanilide goes into solution together with 0'130 gramme of phenacetin, while the remainder of the phenacetin remains in- soluble. If this be separated, its weight, when corrected by an addition of 0*130, will represent the phenacetin present in 1 gramme of the sample (Pharm. Jour., [3], xxi. 377). Phenacetin has been made official in the German Pharmacopoeia (1890), the maximum dose being 1 gramme. It is stated to melt at 135°, and dissolve in 1400 parts of cold, 70 of boiling, water, and 16 of spirit to form neutral solutions. It is dis- tinguished from exalgin and antifebrin by boiling O'l gramme for a minute with 1 c.c. of hydrochloric acid, adding 10 c.c. of water, filtering, and adding to the filtrate 3 drops of a 3 per cent, solution of chromic acid, when a ruby-red colour will be gradually developed. (See Pharm. Jour., [3], xxi. 978.) Strong sulphuric acid should dissolve phenacetin without becoming coloured, while a saturated solution, if free from phenol and acetanilide, will not become turbid on adding bromine-water. The description of phenacetin in the British Pharmacopoeia additions (1890) closely corresponds with the above. The dose is from 5 to 10 grains. Meth7jl-phenacetin, C6H4(O.C2H_^).N(CH3)(C2H30). This body is prepared by treating para-phenacetin in xylene solution with sodium, and causing the resultant sodium -derivative to react with methyl iodide (Pharm. Jour., [3], xxi. 81). The new product distils at about 300° C. as an oil, which crystallises on standing. It may be purified by recrystallisation from alcohol METHACETIN. 85 or ether, when it forms colourless crystals, moderately soluble in water, and having marked narcotic as well as antipyretic characters. Amido-paraphenacetin, C6H4(O.C2H5).NH(CO.CH2.NH2). The hydrochloride of this base is readily soluble in water and alcohol, and has been introduced, under the name of " phenocollum hydro- chloricum,'* as an antipyretic and antirheumatic. Prolonged boiling with alkalies splits it into para-phenethidine and glycocine. Formyl-paraphenethidine^ CgH4(O.C2H5).NH(CO.H), though hav- ing a constitution similar to acet-phenethidine, appears to have no antipyretic properties, but has been suggested as an antidote in cases of poison iiug by strychnine. Methacetin is the commercial name of para-acet-anisidine, CgH4(O.CH3).]SrH.C2H30. It is, consequently, the lower homologue of phenacetin (page 81). It forms a crystalline powder or small lustrous scales or plates, odourless, but of a faintly bitter taste. It melts at 127° C, and at a higher temperature boils and distils unchanged. It dissolves in 526 parts of cold, or 12 of boiling, water, and is easily soluble in alcohol, acetone, chloro- form, and dilute acid and alkaline liquids. It is less soluble in benzene, and only with difficulty in ether, carbon disulphide, petroleum spirit, and oil of turpentine, but dissolves freely, on warming, in glycerin and fixed oils. In its general reactions and physiological effects, metacetin closely resembles phenacetin, though according to some authorities it has a less powerful, and according to others a more powerful, action. Its efficacy in cases of neuralgia and rheumatism is said to greatly exceed phenacetin, from which it may be distinguished by its physical characters, or by heating it with a quantity of water insufficient for its solution. When thus treated, methacetin melts and solidifies again on cooling, whereas phenacetin undergoes no apparent change. 1 c.c. of hydrochloric acid dissolves O'l gramme of methacetin very easily, whereas the same quantity of phenacetin is mainly undissolved. DiAMIDOPHENOLS. CgH3(OH)(NH2)2. These bodies are weak bases, forming salts which crystallise well and give aqueous solutions which turn brown in the air; and are coloured an intense violet or dark red by potassium bichromate, ferric chloride, or bleaching powder. Triamidophenol. CgH2(OH)(NH2)3. This body is an unstable base resulting from the complete reduction of picric acid, CgIl2(OH)(N02)3, in acid solutions. If alkaline reducing agents be employed, the action does not proceed beyond the formation of dinitro-amido-phenol or picramic acid, C6H2(0H)(NH2)(:N^02)2 (see Part I. page 143). 86 PHENYLENE-DIAMINES. A dilute solution of triamidophenol is coloured deep blue by ferric chloride. Phenylene-diamines. Diamidobenzenes. Three modifications of phenylene-diamine or diamido-benzene, CgH^(NH2)2, are known, differing from each other in properties according to the positions of the amido-groups, thus : — Ortho-Compound. 1:2 Meta-Compound. 1:3 Para-Compound. 1:4 Appearance, . Tablets or plates. Crystalline mass. Tablets or small plates. 140» Melting-point, . . 102°-103° 63' Boiling-point, . . 252° 287° 267' Characters of chloride, hydro- Groups of radiating needles; readily soluble. Concentrically ar- ranged crystals. Readily soluble tablets ; very sparingly soluble in hydrochloric acid. Reaction in neutral solu- tion with sodium nitrite. Separation of amido-azo- phenyleneas a colourless oily liquid. Yellow or brown coloration, or precipitate of triamidoazo- benzene. No reaction. Ortho-phenylene-diamine is distinguished from its isomerides by its reaction with sodium nitrite, and by the separation of ruby-red needles on adding ferric chloride to the solution of its hydrochloride. On treating an alcoholic solution of the base with a drop of phenanthraquinone dissolved in glacial acetic acid, and boiling for a short time, a bright yellow precipitate of diphenylene-quinoxaline, C20HJ2N2' ^^ formed. It con- sists of small needles which are coloured a deep red by strong hydrochloric acid, and its production affords the most delicate reaction for ortho-phenylenediamine. Its isomerides do not give the reaction, but its homologue, ortho-toluylenediamine, behaves similarly. Meta-phenylene-diamine may be prepared by the reduction of meta-dinitrobenzene (Part I. page 178, footnote). It often remains in a state of superfusion for some time, but is instantly solidified by adding a crystal of the solid substance. Metaphenylene-diamine is sparingly soluble in water, the solution being alkaline in reaction. It is readily soluble in ether, and may be extracted by this solvent from alkaline aqueous liquids. It is a di-acid base, the hydrochloride being CgH4(NH2)2,2IICl. The reaction of metaphenylenediamine with sodium nitrite is characteristic and extremely delicate. It is due to the formation of Bismarck or phenylene hroiun (Part I. page DIAMIDO-BENZENES. 87 180), and b}'- means of it one part per million of nitrous acid can be detected in water. Metaphenylenediamine possesses marked poisonous properties, its physiological action resembling that of the leucomaines and ptomaines. Dubois and Vignon {Compt. Rend., evil. 533) experimented on dogs, and found that a dose of O'l gramme per kilogramme of the animal produced salivation, vomiting, diarrhoea, abundant excretion of urine at intervals, and death by coma in twelve to fifteen hours. Besides these severer symptoms, all those of intense influenza were produced, such as acute coryza and sneezing, coughing, and extreme depression. Para-phenylene-diamine occurs in aniline tailings (page 67). It may be prepared by the reduction of paranitracetanilide. It is but slightly soluble in water, but readily in alcohol and ether. When heated with dilute sulphuric acid and manganese dioxide it yields q u i n n e, CgH^Og, which reaction distinguishes it from its iso- mer! des. On passing sulphuretted hydrogen through a solution of the hydrochloride, and then adding ferric chloride, thionine or Lauth!s violet is formed (Part I. page 285). Para-phenylenediamine possesses poisonous properties similar to those of meta-phenylenediamine, but death occurs more rapidly than with the latter base. It also exerts a special action on the eye, which is gradually forced out of its orbit by the swelling of the con- junctiva or intra-orbital cellular tissue; while the lachrymal glands are blackened by a deposit of pigment (compare "Toluylene- diamines"). Dimethyl-par aphenylenediamine, H2N. €5114.^(0113)2, may be ob- tained by the reduction of nitrosodimethyl-aniline or of helianthin (Part I. pages 188, 211). A neutral solution of the hydrochloride is coloured a beautiful purple by ferric chloride ; and on treating it with a hydrochloric acid solution of sulphuretted hydrogen, and then adding ferric chloride till the smell of sulphuretted hydrogen has disappeared, a fine blue coloration is obtained, due to the for- mation of methylene blue (Part I. page 285). This reaction is the most delicate test for TOLUYLENE-DIAMINES. DiAMIDOTOLUENES. CgH3(OH3)(!N'H2)2. These bases closely resemble the phenylene-diamines. The ortho- jpara-modification (OH3 : NHg : NHg = 1:2:4) is obtained by the reduction of ordinary dinitro toluene. It melts at 88°, is used for the production of toluylene red and toluylene orange. The 1:3:4 (meta-para) modification is obtained by nitrofying acet-paratoluide, saponifying, and reducing.^ Janovsky {Jour. Soc. Chem. Ind.y ^ This modification appears to be identical with the paratoluylenediamine isolated by Hell and Schoop from aniline tailings [Berichte, xii. 723). 88 TOLUYLENE-DIAMINES. ix. 383) gives the following table of reactions of neutral or slightly acid solutions of the two isomeric toluylene-diammes : — Eeagent. Ferric chloride. Potassium bichromate. Potassium ferricyanide. Bromine water. Platinic chloride. Auric chloride. Potassium nitrite. Solution of bleaching powder. a-Toluylene-diamine. CH3:NH2:NH2 = 1:2:4 No change at first ; after standing for a long time an orange coloration. YeUowish-brown tion. colora- Olive-green plates. Yellowish-white tate. Yellowish-brown tion. crystalline precipi- colora- Brown precipitate. In very dilute solutions a golden-brown coloration ; in concentrated a brown precipitate. B,eddish - brown colora- tion and then a light brownish-yellow precipi- tate. /3-ToluylenB-diamine. CH3:NH2:NH2 = 1:3:4 Wine-red coloration. Reddish-brown precipi- tate. Dark-red coloration. Brown flocks and magenta- red solution. Reddish-brown tate. precipi- Red solution with blue reflex and metallic mir- ror in the cold. No coloration, but a sal- mon-coloured precipi- tate. Dark-red coloration, then an olive-green precipi- tate. The foregoing reactions are available, even in presence of other substances, for the detection and identification of the toluylene- diamines, which often result from the reduction of azo-dyes. The toluylene-diamines are powerful poisons (compare " Meta- phenylenediamine," page 87).^ Benzidine. Dipara-amido-diphenyl. Ci2Hi2N2 = NHj.C8H,.C,H,.NH2 (1, 4 : 1, 4). This body is obtained by the reduction of diparanitro-diphenyl, NOg.CgHg.CgH^JSTOg, by nascent hydrogen (tin and hydrochloric acid). A readier method of preparation is the following : — An alcoholic solution of 10 parts of azobenzene, CgH^.N : N.CgHg, ^ Engel and Kiener {Compt. Rend., cv. 465; Jour. Chem. Soc, liv. 81) find the symptoms to vary considerably according to the time required to pro- duce death, which ranges from a few hours in acute cases to several weeks in chronic cases. When death ensues in a few days, there is always icteria, and often hsemoglobinuria, and the urine is loaded with fat and yellow and brown pigment-granules, which sometimes contain iron. This ferruginous pigment accumulates in the spleen and marrow, and seems to be formed from the haemo- globin in the protoplasm from the cellules, and not from the red corpuscles. BENZIDINE. 89 is treated with a solution of 3 J parts of tin in concentrated hydrochloric acid, and the liquid warmed for some time. Hydrazobenzene, C6H5.NH.NH.CgH5, is formed, which by intramolecular change is converted into benzidine (dihydro- chloride). Some of the isomeric ortho-para-diamido- diphenyl is simultaneously formed, and a portion of the azobenzene is reduced to aniline, CgHg.NHg. The alcohol is distilled off, the residue dissolved in water, and sulphuric acid added. The nearly insoluble benzidine sulphate is precipitated, while the sulphates of the isomeric base and of aniline remain in solution. The precipitate is washed with dilute hydrochloric ^cid (to remove tin salts) and treated with ammonia, the liberated benzidine being crystallised from dilute alcohol. Ben- zidine is also produced by treating azobenzene with sulphur dioxide. Benzidine is manufactured on a large scale by heating nitrobenzene with caustic soda, a little alcohol, and the proportion of zinc-dust theoretically sufficient to reduce it to hydrazobenzene. The product is washed with cold dilute hydrochloric acid to remove oxide of zinc. On subsequently heating it with dilute hydrochloric acid, it is converted into benzidine dihydrochloride. Benzidine forms large pearly plates, which are colourless when pure, but rapidly turn red on exposure to the air. It melts at 122°, and boils with partial decomposition above 360°. Benzidine is very sparingly soluble in cold, but readily in boiling, water, and is easily soluble in alcohol and ether. Benzidine is a well-defined di-acid base, forming crystallisable salts. The sulphate is very sparingly soluble in water, even when boiling. On adding potassium bichromate to a concentrated solution of benzidine hydrochloride, a deep blue crystalline precipitate, con- taining Ci2^8(^^2)2^^^4' ^^ immediately formed. The same precipitate is formed on warming, even in very dilute solutions. When chlorine-water is added in small quantity of a solution of benzidine hydrochloride, the liquid assumes a fine blue colour, which on further addition of chlorine-water changes to green ; and ultimately, when the chlorine is in excess, a flocculent red pre- cipitate is formed, apparently containing C^gH^OlgNgO, soluble in alcohol and ether, and forming a colourless compound on reduction. Bromine-water and a solution of bleaching powder act similarly; but in presence of a large quantity of free hydrochloric acid bromine forms tetrabrombenzidine, melting at 285°. With nitrous acid, solutions of benzidine salts react to form tetrazo-compounds which react with phenols, phenol- sulphonic and carboxylic acids, amidosulphonic acids, &c., to form the important class of bodies known as " tetrazo-dyes," of 90 NAPHTHYLAMINES. which congo-red is the type (Part I. page 206), and which are remarkable for dyeing cotton without a mordant, Orthotolidine. NH2.C6H3(CH3).(CH3)C6H3.NH2. This base is homologous with benzidine, and is prepared from ortho-nitro- toluene by the same process by which benzidine is prepared from nitrobenzene. It melts at 128°, and presents a close resemblance to benzidine. The tetrazo-dyes prepared from it are less readily altered by acids than are the similar dyes prepared from benzidine. NAPHTHYLAMINES AND THEIR ALLIES. When naphthalene, C^oHg, is treated cautiously with nitric acid, nitronaphthalene, Cj^qH7(N02), is formed, and this by treatment with reducing agents is converted into amido-naph- thalene or naphthylamine, CioHy(NH2). These reac- tions are strictly analogous to those by which aniline is prepared from benzene, and the product is known as alpha-n a p h t h y 1- amine. But by other reactions the isomeric beta-n a p h t h y 1- amine may be obtained. These two bodies differ from each other in a notable manner, as indicated in the following table : — Alpha- Beta- Naphthylamine. Naphthylamine. OH C.NHo CH CH /\/\ /\/\ _ HC C CH HC C C.NH2 Structural Formula, . II 1 1 c HC C CH HC CH \y^ X/\^ CH CH CH cn Melting-point, . . . 50° 112° Boiling-point, . . . 300° 294° Odour, Disagreeable; persistent. None. Appearance, .... Flat needles or prisms. Pearly plates. Reactions of hydrochlo- .ride in solution :— With ferric chloride, . Blue precipitate. No reaction. With nitrous acid in Yellow colour, turned No reaction. alcoholic or acetic crimson by hydro- acid solution. chloric acid. With sulphanilic acid Red coloration. ... and sodium nitrite. followed by hydro- chloric acid, ALPHA-NAPHTHYLAMINE. 91 a-Naphthylamine. CioH^.NHg. This base is obtained (as already stated) by the reduction of nitronaphthalene, or by heating a-naphthol with the double com- pound of chloride of calcium and ammonia.^ a-Naphthylamine has a most disgusting and persistent odour, re- sembling that of faeces. It turns violet or brown in the air, but when purified by sublimation this change occurs very slowly, and only on exposure to air and light. It is slightly volatile with steam. a-Naphthylamine is nearly insoluble in water, but very soluble in alcohol and ether. It forms a series of readily-crystallisable, easily-soluble salts. On adding ammonia to a solution of the sul- phate, the free base is precipitated in white silky needles. On adding ferric chloride to a solution of a-naphthylamine, or of one of its salts, an azure blue precipitate ofnaphthamein is produced, which rapidly becomes purple, but is unchanged by treat- ment with sulphurous acid. Other oxidising agents (e.^., chromic acid, bleaching powder) produce precipitates varying in colour from blue to violet or red. On adding an alcoholic solution of nitrous acid to a solution of a-naphthylamine in alcohol or glacial acetic acid, a yellow colour is produced, which, on adding a little hydrochloric acid, changes to an intense violet or magenta colour ; or, in presence of only traces of naphthylamine, to a reddish colour. If to a cold solution of alpha-naphthylamine sulphanilic acid and sodium nitrite be added, a red colour is produced on adding hydro- chloric acid, owing to the formation of amidonaphthyl- azobenzene-sulphonic acid, CioHg(NH2).!N'2-^6^4(^^3-^)- a-Naphthylamine is used for the preparation of Magdala red (Part I. p. 257), certain azo-dyes, and naphthalene fancy-colours on cotton. Commercial u-naphthylamine ought to melt at 50° C, and be almost completely soluble in dilute hydrochloric acid. Naphthalene, the presence of which causes incomplete solubility, may be deter- mined by distilling the acidulated solution in a current of steam, agitating the distillate with ether, separating the ethereal layer, evaporating it at a low temperature, and weighing the residue. ^ On a large scale, a-naplitliylamine is prepared in a manner very similar to that employed for the production of aniline. Nitronaphthalene is reduced by iron and hydrochloric acid at a temperature of about 50°. When the reduction is complete, milk of lime is added, and the naphthylamine distilled off by the aid of superheated steam. The crude product is purified by redistillation, when it is obtained as a nearly colourless oil, which solidifies to crystalline cakes of a greyish colour. It appears to be wholly free from )8-naphthylaraine, but contains an impurity which is probably l:l'-naphthylene-diamine, CioHe(NH2)2 (0. N. Witt, Dingl. Polyt. Jour., cclxv. 225). 92 THERMINE. P Naphthylamine. CioH^.NHg. This modification of amidonaphthalene is most readily obtained by heating ^-naphthol under pressure with ammonia at 160°, or with the double compound of zinc chloride and ammonia at 200°— 210°. ^-Naphthylamine is odourless and more stable than the a-modi- fication. It volatilises in a current of steam, and is slightly soluble in cold, more readily in hot, water, the solution exhibiting a blue fluorescence, which, however, is not shown by /3-naphthylamine salts. |8-Naphthylamine gives no coloration with oxidising agents, nor with nitrous and hydrochloric acids in alcoholic solution. Commercial (3 -naphthylamine ought to melt at 112° C, and be completely soluble in dilute hydrochloric acid. TETRAHYDR0-/5-NAPHTHYLAMINE. CjoH^^.NHg. This base has been introduced into medicine under the name of " T h e r m i n e." It is a colourless, slightly viscous liquid, of peculiar odour. It is a strong base, a drop soon becoming converted into a crystalline mass of the carbonate on exposure to air. The hydrochloride forms well-defined white crystals, melting at 237°, and readily soluble in water, alcohol, and amylic alcohol. The physiological efi'ects of thermine embrace the two strongly - marked characteristics of mydriasis (accompanied by pain) and elevation of the temperature, which latter effect has been observed to the extent of 4J° C Naphthylamine-Sulphonic Acids. When treated with dilute sulphuric acid, the naphthylamines dissolve easily with formation of sulphates, but by the action of concentrated sulphuric acid at a high temperature they are con- verted into sulphonic acids. Thus when a-naphthylamine is heated with fuming sulphuric acid, two isomeric sulphonic acids are formed, one of which is readily soluble in water, while the other is only sparingly soluble. The latter modification crystallises in small lustrous needles, and in aqueous solution exhibits a beautiful fluorescence. Similarly, /3-naphthylamine yields on sulphonation several isomeric acids. According to A. G. Green (Ber., xxii. 721), at moderate temperatures (100° C.), and with ordinary sul- phuric acid, the product is a mixture of a and y acids, having their sulphonic groups in the a-position ; while at a higher tem- perature (160°— 170°) /5 and S modifications are produced, having their sulphonic groups in the /9-position. The ammonium salt of the /5-acid is less soluble than the three isomeric salts, and by this means the ^-acid can readily be isolated. The a-naphthylamine-sulphonic acids may also be obtained by treating nitronaphthalene, C^jHyNOg, with fuming sul- NAPHTHALENE-DIAMINES. 93 phuric acid, and reducing the resultant nitronaphthalene-sulphonic acid, CioHg(]Sr02)(S03H), with iron and hydrochloric acid. Two isomeric amido-sulphonic acids are obtained in this case also. The naph thy laraine-sul phonic acids are also conveniently pre- pared by heating the corresponding naphthol-sulphonic acids (Part I. pages 194, 207, 208) with ammonia under pressure. Naphthylamine-disulphonic acids may be obtained by reactions similar to those described above. Two of these derivatives of y8-naphthylamine are technically known as " Amido- acid R" and "Amido-acid G." The latter, or y-acid, is not capable of reacting with diazo-compounds, but the first, or a-acid, produces colouring matters which yield colourless solutions on reduction.^ N aphthylene-Diamines. CioH6(NH2)2. These bases may be formed by heating the corresponding dihydroxynaphthalenes with ammonia, by the reduction of the dinitronaphthalenes, and in other ways. The following table exhibits their leading properties : — Position of the Amido-Groups. ai, a2 ai, 0-3 . ai, a4 «!, ^1 Mode of preparation, From a-nitro- From a-di- From i8-di- By reducing From aj - a3. naphthyl- nitro-naph- nitro-naph- azo-com- Dihydroxy- amine by re- thalene. thalene. poundsof/3- naphthalene. duction, and napthyl- from azo- amine. compounds of a-naph- thylamine. Form of crystals, . Leaves. Needles. Needles. Plates. Needles. Melting-point, . . 120° C. 189° -5 C. 66° -6 C. 95° C. 189° C. Hydrochloride, . . Plates. Needles (?). ... Plates. Plates. Sulphate ... Needles. ... Plates. Needles. Reaction of the hy- Green colora- Blue colora- Chestnut- Green, then Blue colora- drochloride with tion. tion; then brown pre- yellow tion; then ferric chloride, blue precipi- tate. cipitate. coloration ; brown pre- cipitate. precipitate. Action of nitrous Sol. tetrazo- Sol. tetrazo- Vermilion ••• Sol. tetrazo- acid, compound. compound. precipitate. compuund. Action of the azo dye- Do not dye. Dye the fibre. ••• ... Dye the fibre. stuffs on unmor- danted cotton. ^ For further information respecting the naphthylamine-disulphonic acids and the naphthalene derivatives generally, see various papers by Armstrong and Wynne {Jour, and Proc. Chem. Soc, 1890, 1891), and the article by Wynne in Thorpe's Dictionary of Applied Chemistry, ii. 6i9 et seq. 94 AMIDO-NAPHTHOLS. Amidonaphthols. CioH^COHX^H^). These bodies are unstable bases obtained by the action of reducing agents on the nitro- or nitroso-naphthols, or on certain azo-dyes. The following table shows the leading differences of the principal members of the group : — a- Amido- /3-Amido- a-Amido- a-naphthol. a-naphthol. /3-naphthol. Relative position of 1:4 1:2 2:l(or4) the OH and NHg groups. Mode of formation. Reduction of 1:4 Reduction of 1:2 Reduction of the nitro - a-naphthol nitro - a-naphthol nitro-/3-naphthol, melting at 164°; or melting at 128°; or melting at 103°; of of Orange I. (Part of nitroso-a-naph- nitroso-^-naph- I. page 284). thol. thol; or of Orange II. (Part I. page 184). Characters of free Unstable. Unstable. Colourless scales ; base. slightly soluble in water ; oxidised in the air. Ethe- real solution ex- hibits violet fluo- rescence. Reaction on agitat- Dirty green colora- Permanent grass- Brown coloration. ing alkaline solu- tion, changing to green colour, and tion with air. yellow. green scum sol- uble in alcohol to pure green solution. Or violet naphthoquin- onimide— Reaction with bro- Yellowish-white Yellowish or green mine water. needles precipi- precipitate (the tated, even in very same with ferric dilute solutions. chloride). Characters of hydro- Long white needles White laminsB. chloride. or acicular plates. White lustrous With bleaching needles; readily powder yields soluble in water, C20H12N3CI, which but only spar- | separates from tngly in dilute ; acetic acid solu- hydrochloric acid. tion in needles. melting at 85° and exploding at 130°. Product of oxida- Theoretical yield of /5-naphthoquinone. /3-naphthoquinone. tion with chro- a-naphthaquinone. mic acid mixture. Amidonaphthol-sulphonic Acids. These bodies result from the reduction of azo-derivatives of the respective diazobenzene com- pounds of naphthol-sulphonic acids. Thus, for instance, by treat- ing the four known modifications of /3-naphthol-monosulphonic acid with stannous chloride, 0. N. Witt obtained the following amido- sulphonic acids {Berichte, xxi. 3468, 3489): — AMIDONAPHTHOL-SULPHONIC ACIDS. 95 1. Amido-/3-naphthol-^-sulphonic acid, from Schaffer's acid (Parti, page 194). 2. Amido-/3-naphthol-a-sulphonic acid, from Bayer's acid (Part I. page 194). 3. Amido-/3-naphthol-5-sulph.onic acid, from Casella's acid (Part I. page 208). 4. Amiio-^-naphthol-y-sulphonic acid, from Dahl's acid. The first of these acids has recently received a novel application as a photographic developer under the name of eikonogen (R. M e 1 d 1 a, Jour. Soc. Chem. Ind., viii. 968). It may be obtained by the reduction of the azo-dye known as '* Crocein orange," " Brilliant orange" or "Ponceau 4GB" (Part I. page 184), obtained by the reaction of Schaffer's ^-naphthol-sulphonic acid (Part I. page 194) on diazobenzene chloride. It may be obtained from its nitroso- derivative by dissolving the ammonium or other salt of Schaffer's acid in ice-cold water, together with an equivalent quantity of sodium nitrite, and then gradually adding hydrochloric acid to acid reaction, when the nitroso-acid is at once formed, and imparts an orange colour to the solution. The acid can be purified by conversion into a barium or calcium salt (Jour. Chem. Soc, xxxix. 44), or the solution may be at once reduced to the amido-acid by treatment with zinc-dust or stannous chloride. Two other amid o-/5-n a p h t h o 1-m onosulphonic acids are obtainable by heating with caustic alkali, to 200°-280°, the two j8-naphthylamine-disulphonic acids respectively obtained by treat- ing with the two isomeric ^-naphthol-disul phonic acids R and Y (described in Eng. Patent, 1878, :N'o. 1715). They differ from the amidonaphthol-sulphonic acids, referred to above, in yielding diazo- compounds. They can also be combined with various tetrazo-com- pounds, giving blackish violet or blue-black dye-stuffs. The following table shows some of their reactions (Eng. Patent, 1889, No. 15176). R salt is the sodium salt of y8-naphthol-disulphonic acid : — R. Y. Solution of neutral salts in water. Reaction with ferric chlo- ride. Reaction with bleaching- powder solution. Diazo-compound. Combination of the diazo- compound with " R salt" in an alkaline solution. Violet fluorescence. Dark blue coloration, turn- ing to dun colour. Light yellowish-brown coloration, which dis- appears rapidly on add- ing excess of the reagent. Reddish orange. Claret red. Blue. Dirty claret-red coloration. Dark reddish-brown colora- tion, which disappears graduaUy on adding ex- cess of the reagent. Canary yellow. Violet-black. 96 PYRIDINE AND ITS ALLIES. PYRIDINE BASES. C„H,„.,K These bases, raetameric with aniline and its homologues, are con- tained in coal-tar naphtha ; in shale-oil ; in peat-tar ; in tobacco- smoke ; and, together with ammonia and methylamine and its homologues, in the product called " Dippel's oil," obtained by the distillation of bones and other animal matters. Pyridine itself has received several technological applications, and is of great interest theoretically in relation to the alkaloids. Pyridine may be regarded as benzene, in which one of the CH groups has been replaced by N.^ Thus : — N CH=CH^ ^CH=CH^ Benzene. Pyridine. The homologous bases are derived from pyridine by the sub- stitution of CHg, CgHg, &c., for one or more of the hydrogen atoms, and consequently admit of isomeric modification according to the position of the substituted atoms in the chain. The following is a list of the bases of the pyridine series. The ^ The relationship between various organic bodies (hypothetical and other- wise), of which the names commence with the root pyr is shown by the follow- ing formulae (compare page 30). The hydrocarbon pyrene has the constitution of a phenylene-naphthalene, and is not related closely to the bodies tabulated below: — \- Piazine. T^/:CH.CH: ^ \ .CHtCH. Piazine Dihydride. ^\.CH2.CH2.|^ Piazine HexahydHde (Diethylene-diamine). B»{;gg:gi^:}NH Quinone. co{:gg:gg;}co "{ Pyridine. :CH.CH:\pp, CH Pyridine Dihydride. j^/:CH.CH:\, ^1.CH2.CH2.r Pyridine Hexahydride (Piperidine). °{ Pyrone. .CH:CH.\co .CH:CH./^" Pyrrol. ^T^/.CH:CH. ^^ i .CH:CH. HN Pyrroline. /.CH:CH2.(. t.CHg.CHa.) Pyrrolidine. ^^\.CH2.CH2./ HN Pyridone r.CHrCH. \.CH:CH. CO Pyrazole. ^^(!cH:CH.r Pyrazoline. ^^{iCHa.CHa.} Pyrazine. „jf(.NH.CH2.> ^^ \ .CH2.Cfl2:f Pyrazolone. .COCH2. Piazine has merely a hypothetical resistance, and the dihydride is known only through its diphenyl-derivative. Pyrone and pyrazine, also, are only known by their derivatives. Pyrazole, C3H4N2, has been recently obtained by acting on hydrazine hydrate with epichlorhydrin in presence of zinc chloride : — 2N2H4 + C3H5CIO = C3H4N2 -f- HCl -h H2O + 2NH3 . Pyrazole is a basic substance crystallising in needles, melting at 70°, and boil- ing at 188°. It is readily soluble in water, alcohol, and ether. PYRIDINE BASES. 97 boiling-points and specific gravities are only approximate, as the isomeric modifications exhibit sensible differences in their physical properties. Formula. Base. Boiling-Point. •c. Specific at 0' C. Gravity o«22°C. CgHsN Pyridine. 115-116 •9858 ... CfiHyN C7H9N CfiHioN Picoline (o-Methyl- Pyridine). Lutidine (y-Ethyl- Pyridine). CoUidine. 133-135 154 179 •9613 •9443 •921 •933 C9H13N Parvoline. 188 •906 C10H15N Corridine. 211 •974 CuHirN Eubidine. 230 ... 1-017 CiafligN Viridine. 251 ... 1-024 From the above table it is evident that the boiling-points rise as the number of carbon-atoms in the molecule increases. For the first four members of the series the specific gravity diminishes, with increase in the molecular weight, but with the higher mem- bers the reverse is recorded as being the case. The lower members are miscible with water in all proportions, but collidine and its higher homologues are insoluble, or nearly so, in water. If a drop or two of pyridine, or one of its homologues, be warmed in a test-tube with a similar quantity of methyl iodide, the product mixed with powdered caustic potash and moistened with water, and heat applied, a highly characteristic and peculiar odour is pro- duced, owing to the formation of a pyridic dihydride. It resembles that of a mixture of mustard oil and isonitrile. The least trace of pyridine or its homologues can be detected in this way. A some- what similar odour is obtained when a quinoline base is treated in the same manner, but the aniline bases and piperidine do not give the reaction. The foregoing test, due to A. W. H f m a n n, is modified by d e C n i n c k as follows : — 1 c.c. of the base is gradually mixed with 2 c.c. of methyl iodide, the liquid being cooled during the mixing. The crystalline product is dissolved in about 5 c.c. of alcohol, the liquid heated to boiling, and very con- centrated caustic potash solution dropped in. A blood-red colour is produced, and the liquid finally becomes dark brown if a pyri- dine base be present {Jour. Chem. Soc, 1. 897). Piperidine, spar- teine, cicutine, and the aniline bases give no similar reaction. The bases of the pyridine series are tertiary monamines, and VOL. III. PART II. G 98 PYRIDINE BASES. form with alkyl iodides compounds^ which are not decomposed by caustic potash, but yield caustic hydroxides by reaction with silver oxide (compare page 18). The pyridine bases and their salts exert a soporific action on the higher animals. When inhaled, pyridine acts as a respiratory sedative. It has been successfully used as a heat stimulant and as a topical antiseptic in diphtheria. Penzhold found pyridine to act as a general antiseptic, especially as regards mycelia. On the lower animals, pyridine and its homologues act as violent poisons, and have been successfully employed in 0*2 per cent solution for destroying the scab-acarus in sheep, the vine-louse, and other injurious insects. The pyridine bases appear to be little, if at all, inferior to nicotine for these purposes, and have also been employed in disinfecting powders. Isolation of Pyridine Bases. For the preparation of the pyridine bases, bone-oil, or the frac- tion of coal-tar or shale-oil boiling between 80° and 250°, should be agitated with sulphuric acid diluted with twice its measure of water, the treatment being repeated to ensure the complete solution of the bases. The acid liquid is separated and distilled (or boiled by a current of steam) till the vapours no longer redden a slip of fir-wood moistened with hydrochloric acid, showing that all the pyrrol has been driven off. The liquid is then filtered through linen to separate tarry matters, an excess of caustic soda added, and the whole distilled with steam as long as bases continue to pass over, as indicated by the production of fumes by contact of the vapours with hydrochloric acid. The distillate is allowed to cool, and is then treated gradually with a large quantity of solid caustic potash or soda, till the pyridine bases separate as an oily layer on the surface of the alkaline ley.^ The upper stratum is separated, and, if it contains aniline, fuming nitric acid is cautiously added and the mixture gradually heated to boiling, whereby the aniline is destroyed, while the pyridine bases remain intact.^ Water is then added, the precipitate filtered off, and the filtrate ^ Their methiodides (PyMel) strongly excite the brain and paralyse the extremities. 2 The potash can be greatly economised, with a loss of some of the higher homologues, by rendering the distillate acid with hydrochloric acid, and con- centrating it to a small bulk by evaporation at a gentle heat before adding caustic potash. 3 Greville Williams destroys aniline and its homologues by heating with potassium nitrite and hydrochloric acid. Hausermann converts the aniline into sulphate, which salt is much less soluble than the sulphates of the olher bases. PREPARATION OF PYRIDINE. 99 again treated with solid caustic potash. The layer of bases is removed, and further treated with stick potash or soda for several days, or until no more alkali dissolves. It is only by prolonged contact with solid caustic alkali that the bases can be freed from water, and it is absolutely necessary to obtain them in a perfectly anhydrous state before attempting to separate them by fractional distillation. This is a very tedious operation, but is greatly facili- tated by operating in a vacuum, and by the employment of a Hempel's tube or Henninger's or Glynsky's bulbs (Vol. I. page 14 ; Vol. II. 501). Goldschmidt and C o n s t a m {Jour. Soc. Ghem. Ind., iii. 159) found that the mixture of bases extracted by vitriol from coal-tar boiled between 92° and 200°, and after repeated fractionation a little passed over below 100°, and about one- half between 114° and 117° (pyridine), while above this tempera- ture no constant boiling-point was observed. Yery little distilled above 160°. The most volatile fraction boiled constantly at 92°— 93°, and was found to be a definite hydrate of pyridine, from which treatment with solid caustic potash caused a separation of absolute pyridine, boiling at 114°— 115°. C. Hausermann has pointed oiit that the amount of sul- phuric acid employed in English tar-works for treating 50 and 90 per cent, benzols is insufficient to remove the bases. He found up to O'lO per cent, of pyridine in commercial 50 per cent, benzol, and 0'25 per cent, in the toluol made from this. Hence the nearly pure benzene, toluene, xylene, &c., now largely manufactured, can be employed with advantage for the preparation of the pyridine bases, as the tedious fractionation has already been accomplished. Thus the base extracted by diluted sulphuric acid from toluene will be nearly pure pyridine ; from xylene, chiefly picoline ; and from burning and solvent naphtha, the higher homologues. English-made toluene yields about 0*5 per cent, of pyridine, and a similar amount of picoline can be extracted from commercial xylene. Pyridine is more commonly made from crude heavy naphtha, and picoline from the lighter creosote oils. Pyridine. C5H,IT;orCH{;^^^;^g;}N This body is the lowest and most important member of the pyridine series of bases. It has been used as an antiseptic and germicide, and is employed in Germany for "denaturating" alcohol. Pyridine is the starting-point in the preparation of several valuable antipyretics, and many of the natural alkaloids are derivatives of it. 100 PROPERTIES OF PYRIDINE. The method of preparing pyridine from tars has already been sufficiently indicated. It may be obtained by several interesting synthetical reactions, as by passing a mixture of acetylene and hy- drocyanic acid through a red-hot tube: — 2C2H2 + CHN = C5H5N. Pure pyridine is conveniently obtained in small quantity by dis- tilling nicotinic acid with lime:— CgH^N.COOH-f CaO = C5H5N + GaCOg. Commercial pyridine may be purified ^ by dissolving 200 c.c. in 400 c.c. (or a sufficiency) of strong hydrochloric acid, filtering the liquid if necessary, and then adding 1000 c.c. of a 30 per cent, aqueous solution of potassium ferrocyanide. The precipitate is filtered off and washed with cold water, in which the hydroferro- cyanides of ammonia and the picolines are easily soluble, while the corresponding salt of pyridine dissolves but sparingly. The washed precipitate is treated with a cold, highly concentrated solution of caustic soda, when the pyridine separates as an oily layer ; and, thus obtained, it contains a considerable but variable proportion of water^ but if desired may be rendered anhydrous by treatment with sticks of caustic potash or soda, which should be renewed until they cease to liquefy on standing. Pure pyridine is a colourless liquid, having a most powerful and persistent odour, and producing a bitter taste in the mouth and at the back of the throat. The vapour causes severe headache. Pyri- dine has a specific gravity of *9858 at 0° C.,^ and boils at 116°*7 according to Anderson, or 115° according to Thenius. The pre- sence of water, which it is difficult to separate completely, and which pyridine absorbs with avidity from the air, greatly reduces the boiling-point. Pyridine seems to form a definite hydrate, C5H5N, SHgO, of specific gravity 1'0219, boiling constantly at 92°-93° C. Pyridine dissolves in water in all proportions, but is precipitated from its solutions by excess of strong potash or soda. It is also miscible with alcohol, ether, chloroform, benzene, and the fatty oils. The effects of pyridine on animals are described on page 98. Pyridine is a powerful base, neutralising acids completely and fuming like ammonia in presence of hydrochloric acid and other volatile acids. It blackens calomel, and precipitates many metallic solutions. Pyridine has no effect on a solution of calcium chloride, 1 Pyridine might probably be advantageously purified from pyrrol and strong- smelling impurities by dissolving it in petroleum spirit and passing hydro- chloric acid gas, the precipitated hydrochloride of pyridine being removed, pressed, and dried at a gentle heat. 2 According to A. Ladenberg {Ber., xxi. 289), the specific gravity of pyridin<3»j»repai«d from the mprpuro-cliloiri^ejs .1^^)053 at 0° 0. DERIVATIVES OF PYRIDINE. 101 but on passing carbon dioxide through the liquid calcium carbonate is precipitated. (No precipitate is produced if aniline be substituted for pyridine in this reaction.) Absolute pyridine has no action on litmus, but in presence of water it turns it strongly blue, though the reaction is not capable of being employed for titrating the base, for which purpose methyl-orange is suitable. On phenolphthalein pyridine has no action. Pyridine is an extremely stable body. It is unaffected by treat- ment with chromic or fuming nitric acid, and these reagents may be employed to free it from aniline and empyreumatic impurities. When chlorine is passed into a chloroformic solution of pyri- dine, an additive-compound, 051X5^,012, separates in white flakes. Bromine forms a similar unstable compound. A substitution- product, dibrompyridine, OgHgBrgN, is formed by heating to 200° a mixture of pyridine hydrochloride and bromine, or the orange-coloured precipitate formed on adding bromine to a solution of pyridine hydrochloride. It is precipitated by adding water to its solution in strong hydrochloric acid, in needles melting at 109° but commencing to sublime at 100°. It is soluble in ether and unacted on by alkalies, acids, or oxidising agents. By reduction with tin and hydrochloric acid, pyridine is converted into piperidine, OgHi^N, identical with the substance obtained by hydrolysis of piperine, the alkaloid of pepper. Dipyridine, CiqH^qN^, is obtained with other products by heating pyridine with sodium. Dipyridine is a base, which melts at 108°, sublimes at a higher temperature in long needles, and forms a hydrochloride, C-^qR^qN 2,^^.01, the solution of which yields with potassium ferrocyanide a blue precipitate which dissolves in hot water to form a purple solution.-^ Para-dipyridylj O5H4N.NO5H4, formed simultaneously with di- pyridine, is a base, crystallising in long needles melting at 114° and boiling at 305° {Jour. Chem. Soc, xliv. 483). Both these bodies yield iso-nicotinic acid on oxidation, while the iso- meric wefa-dipyridyl yields nicotinic acid. Salts op Pyridine. Pyridine forms well-defined salts, most of which are crystallis- able and deliquescent. They are odourless when pure, and can be dried without change at 100°, but become slightly coloured on exposure to air and light. ^ Iso-dipyridine, CioHjoOg, as obtained by fractionating the mother-liquors from the preparation of dipyridine, is a yellow oil which does not solidify in a mixture of snow and salt, even on addition of crystals of pyridine. It has a specific gravity of 1 '08, and is a strong base, sparingly soluble in water, but miscible in all proportions with alcohol and ether. 102 SALTS OF PYRIDINE. Pyridine Nitrate, CgHr^NjHNOg, forms slender, colourless needles, or short thick prisms, very easily soluble in water, but less so in alcohol, and insoluble in ether. Pyridine Sul2')hate,{G^^\-,^fiO^, is crystalline, and extremely soluble in water and alcohol.^ Pyridine Hydrochloride, C^HsISTjHCl. When pyridine is neutral- ised with hydrochloric acid, and the solution evaporated at 100°, a syrupy liquid is obtained, which, on cooling, becomes gradually converted into a mass of radiating crystals. The salt deliquesces in moist air, and sublimes unchanged at a high temperature. It is volatile to a very notable extent at 100°, and hence cannot be dried at that temperature without loss. It is readily soluble in water and alcohol, but insoluble in ether. With platinic chloride, a solution of pyridine hydrochloride yields a yellow crystalline precipitate of the chloroplatinate, (0^11^1^,1101)2^101^, easily soluble in boiling water, less so in alcohol, and insoluble in ether. When pyridine chloroplatinate, free from excess of platinic chloride, is boiled with water for many hours, it is converted into the hydrochloride of platino- pyridine, CioH6PtN2,4HCl, with libration of 2HC1. The new substance is a sulphur-yellow, insoluble body, which evolves jDyridine when boiled with caustic alkali. Pyridine Picrate, C5H5N,HC2H2(]S'02)30, is deposited in beauti- ful yellow needles when picric acid in aqueous solution is added to a solution of an equivalent weight of pyridine. The salt has a remarkable tendency to carry picric acid down with it, so that if twice the equivalent proportion of picric acid be employed, the pro- duct has the percentage composition of an acid salt, Py,2Pc; but its real nature is indicated by its behaviour with ether, which dis- solves out the free jjicric acid, leaving the normal picrate. Pyridine picrate may also be prepared by mixing strong solutions of sodium picrate and pyridine hydrochloride. The salt melts at 162° C, and is soluble in 91 parts of cold water, but in less than 6 parts of boiling water. It is readily soluble in hot alcohol, but requires about 100 parts of the cold solvent, and is deposited on cooling in long, slender, interlaced needles of a beautiful yellow colour. It is only very slightly soluble in ether, chloroform, or benzene, and practically insoluble in petroleum spirit, but it dissolves with great facility in pyridine and cresylic acid. It is readily soluble on warming in ether, benzene, or petroleum spirit containing 10 per ^ In Waits* Dictionary, vol. i. page 755, there is only described an acid sul- phate, which is said to be obtained by evaporating sul[)huric acid with excess of ^rridinfu PYRIDINE COMPOUNDS. 103 cent, of cresylic acid, and is freely soluble in aqueous solution of pyridine and sodium cresylate (A. H. Allen). Pyridine picrate has an intensely bitter taste and nauseous pyridic after-taste. A moderate dose, for example 0*2 gramme, produces violent vomiting. It is a valuable insecticide. Pyridine is remarkable for its tendency to form compounds with metallic salts. These bodies are more or less liable to decomposi- tion by washing or boiling with water, and lose pyridine when heated to 100°, or a somewhat higher temperature. The zinc chloride compound, ZnGlg.SCgHgN, separates as a voluminous white precipitate on treating an aqueous solution of zinc chlo- ride with excess of pyridine. It crystallises from water in long, white silky needles, which, when repeatedly washed, or boiled with water, decompose into pyridine and a basic zinc chloride. The zinc chloride compound dissolves in hydrochloric acid to form a double chloride of zinc and pyridine, ZnCl2,(C5H5N,HCl)2, which forms groups of white lustrous needles. Cadmium chloride behaves with pyridine in a manner similar to zinc chloride, the compound formed, CdCJg.SCgHgN, crystallising in needles and being partially decomposed by a large quantity of water. The cupric chloride compound is precipitated in fine greenish silky needles on adding pyridine to an alcoholic solution of cupric chloride. It is soluble in pyridine, in aqueous solutions of pyridine, and in ammonia. With mercuric chloride, a very dilute aqueous solution of pyridine (1-1000) yields a precipitate which dissolves extremely easily in warm water, and separates out, as the solution cools, in long white needles. With mercuric iodide, pyridine forms a compound which crystallises from alcohol in beautiful white needles. Prom acid solutions of pyridine, phosphotungstic acid throws down a very difficultly soluble precipitate. Detection and Determination of Pyridine. The recognition and determination of pyridine are to a great extent based on the properties and reactions already de- scribed. In the free state, the smell and basic character of pyridine amply suffice for its recognition in the absence of other basic substances of powerful odour, and it is readily liberated from its salts by addition of caustic soda, and obtained free from every interfering substance by distilling its aqueous solu- tion. It may also be extracted from its aqueous solution by agitation with ether, provided that the liquid be saturated with caustic soda. In the absence of ammonia, or other bases, free pyridine may be determined by titration with standard acid and methyl-orange (not 104 DETECTION OF PYRIDINE. litmus). 1 c.c. of normal acid neutralises 0*079 gramme of pyri- dine. From aniline, pyridine is distinguished by not giving any coloured product on adding a solution of bleaching powder, though the liquid acquires a new and peculiar odour. The presence of ammonia in pyridine can be recognised (in the absence of fixed alkalies) by the red coloration produced in the aqueous solution by phenol-phthalei'n, on which pure pyridine has no action. If the indicator be used in considerable quantity, and a low temperature employed (as recommended by J. H. Long, Analyst, xv. 53), the ammonia can be approximately determined by titrating the aqueous solution with standard acid. K. E. Schulze recommends ferric chloride as an indicator (see page 106). According to W. Lang, the traces of pyridine some- times contained in commercial alcohol may be detected and removed by shaking the spirit with powdered zinc chloride ; or, according to W. K i r s c h m a n n, by the addition of an acid solution of aluminium sulphate. In the former case, the pyridine is removed in the form of its zinc chloride compound, and in the latter case pyridine alum is formed. The traces of pyridine sometimes present in fusel oil may be detected by adding picric acid, which occasions a formation of pyridine picrate. For the detection of traces of pyridine in commercial ammonia, H. s t recommends that the sample should be nearly neutralised, when the odour of pyridine may be recognised. By distilling the nearly neutralised liquid, collecting the distillate in hydrochloric acid, evaporating, and extracting the residue with absolute alcohol, a solution is obtained containing but little ammonium chloride. What is present is removed by boiling off the alcohol and adding platinic chloride solution, when, on evaporating the filtrate and adding alcohol, the pyridine chloroplatinate crystallises in smooth, ramifying, orange-red prisms, readily soluble in boiling, but very sparingly in cold, water. Commercial Pyridine, as now produced, consists chiefly of pyridine and picoline. Ammonia is apt to be present in notable quantity, as also pyrrol and other strong smelling impurities.^ A considerable but variable proportion of w a t e r is present. Pyridine is employed in Germany, in conjunction with wood * The pyridine produced at certain works becomes turbid when diluted with more than 40 per cent, of water, whereas the best makes are miscible with water in all proportions. On distilling the former brands the disturbing im- purity is left in the '* tailings." ASSAY OF PYRIDINE. 105 spirit and turpentine, for " denaturating" spirit. An article intended to be used for this purpose is required to answer to the following official tests. 1. The colour must not be deeper than straw-yellow. 2. If 1 c.c. of the sample be dissolved in 250 c.c. of distilled water, and 20 c.c. of the resultant solution be treated with a 5 per cent, aqueous solution of cadmium chloride, a distinct turbidity should appear in a few moments.^ 3. When 100 c.c. of the sample is distilled (in a small metal flask provided at the top with a small globe, which is connected with a Liebig's condenser, a thermometer being fitted to the globe, and a moderate heat applied) so that the distillate passes over in separate drops, 90 per cent, should have distilled when the thermometer stands at 140° C. 4. When the sample is mixed with twice its measure of water it must wholly dissolve, and no oily drops must separate even after long standing. 5. Four drops of the sample heated on platinum foil over a Bunsen burner should burn with a sooty flame, and leave no residue. 6. When 20 c.c. of the sample is shaken with an equal measure of a solution of caustic soda of 1 '4 specific gravity, a layer of anhydrous bases, measuring at least 18 c.c. ( = 90 per cent.), should separate out on standing. The last test is now usually replaced by one prescribing the use of solid caustic potash. 50 c.c. measure of the sample is placed in a graduated cylinder, furnished with a stopper, and a long stick of potash immersed in it. The alkali gradually absorbs the water from the pyridine, and forms a lower layer of saturated solution. A second stick is added as soon as the first has sunk much below the surface of the pyridine, and is followed by a third if the second liquefies completely or considerably. Agitation should be avoided, and care must be taken that the last stick is left in contact with the upper layer of bases until the action is at an end. It is then cautiously removed with a bent wire, or broken down by a glass rod, and the volume of the layer of anhydrous bases carefully observed. By this test, commercial pyridine usually shows from 8 to 10 per cent, of water ( = 92 to 90 per cent, of anhydrous bases). Instead of determining the water, K. E. Schulze recommends titration of the bases with standard acid. For this purpose 5 c.c. of the sample should be dissolved in water, and the solution diluted to 100 c.c. To 20 c.c. of this solution (=1 c.c. of the sample) is added 1 c.c. of a 5 per cent, aqueous solution of ferric chloride. * "Wepper and Liiders {Jour. Soc. Chem. Ind., vii. 762) have pointed out the unreliable character of this test, which they attribute to the varying composition of cadmium chloride. Of two samples of the salt, only one gave the reaction with pyridine. They recommend the employment of a stronger solution of the pyridine than that prescribed in the test. 106 PIPERAZINE. Normal sulphuric acid is then run in slowly with agitation, till the precipitated ferric hydroxide is redissolved. 1 c.c. of normal acid (containing 49 grammes of HgSO^ per litre) corresponds to '079 gramme of pure anhydrous pyridine, or to '095 gramme of picoline. Pyridine intended for pharmaceutical or medicinal use should not be altered by light ; a 1 per cent, solution in water should not be reddened by phenol-phthalein (presence of ammonia) ; and 5 c.c, to which 2 drops of decinormal permanganate have been added, should retain a red colour for at least an hour. Piperidine. C5HiiN = C5H,(H5)NH. This body has the constitution of a pyridine hexa- hydride.^ It is obtained by the reduction of pyridine by nascent hydrogen. The following formulae show the relation of pyridine to piperidine and piperazine:^ — ch{SSSS:}^^ ch4:Ch.ch.}^h hn{;Ch.ch.|kh Pyridine. Piperidine. Piperazine. Piperidine is also obtained by rapidly heating pentamethylene- diamine (amylene-diamine) hydrochloride : — C5Hio(NH2)2.HCl - CgHiiN + NH.Cl . Piperidine is also produced by the hydrolysis of piperine, CigHjgNOg, the alkaloid of pepper, which, on boiling with alkalies, splits into piperidine and pip eric acid:^ — Ci,Hi,N03+H,0 = C,HuN + Ci,Hi„0, . Piperidine is a colourless limpid liquid, of peculiar odour, re- sembling at the same time that of pepper and ammonia, and has ^ Pyridine di-and tetra -hydrides and their homologues are capable of existing theoretically. The latter class, called piperideins, have been prepared by the action of caustic soda and bromine on the piperidines {Ber., xx. 1645). 2 Piperazine or Piperazidine is probably identical with diethylene- diamine. It is a strong base, molting at 104°-107°, boiling at 135°-138°, and absorbiog carbon dioxide from the air. Piperazine has neither caustic nor toxic properties, and passes through the system unchanged, but dissolves uric acid in large amount, forming the neutral urate, C4HioN2,C5H4N408. Piperazine phosphate forms four-sided tabular crystals, which character, and those of the bismutho-iodide, distinguish piperazine from spermine, C4H8N2, which otherwise it closely resembles. ' A small quantity of piperidine is said to be obtained on distilling pepper with water alone, probably owing to partial decomposition of the piperine by water or a ferment (W. Johnstone, Analyst, xix. 46). PIPERIDINE. 107 a very caustic taste. It boils and distils unchanged at 106°, and dissolves in all proportions in water and alcohol. When piperidine is treated with water heat is evolved. Piperidine is a powerful base. Its aqueous solution restores the blue colour of reddened litmus-paper, and behaves like ammonia with metallic solutions, except that the precipitates produced with salts of zinc and copper are not soluble in excess. Piperidine absorbs carbon dioxide from the air, and if the gas be passed into a solution of calcium chloride, to which piperidine has been added, calcium carbonate is precipitated. Piperidine may be estimated by titration with standard acid, using either litmus or methyl-orange as an indicator. Piperidine forms a series of readily crystallisable salts, most of which are soluble. The cliloroplatinate^ {C^-^^)^^iG\Q, forms orange needles, very soluble in water, but less so in alcohol. Piperidine is a secondary amine. When dropped into cooled methyl iodide it forms the compound CgH^oC^-^s)-^'^-'^- When distilled with alkali this yields the free base methylpiperidine, which, when heated under pressure with methyl iodide, gives the iodide of dimethyl-piper ylene-ammonium, C5Hjq(CH3')2NI. The homologues of piperidine are called by Ladenburg pipecolines, C5Hio(CH3)N, lupetidines, C5H9(CH3)2N, copellidines, C,H3(CH3)3N, &c. Piperidine is closely related to a number of the natural alkaloids besides piperine, as will be seen from the following formulae : — Conine. Dextro-a-normal- ) .^^ ( CH2.CH(C3Hy) ) ^^t propyl-piperidine. J ^^2|cH2.CH2 J^^ CoNHYDRiNE. Probably hy- | ^„ ( CH2.CH(0H) "( ^j.^ ^ . droxy-conine. | ^^2 1 CH2.CH2 | ^(^sHy) Tropine. Methyl-a-hy- ) , ^^ ^ ,^ . . droxyethyl- tetrahydro- I GR^ \ ^^2^^{^2^a^^) I jsf (CH3) pyridine. J KicoTiNE. Hexahydro-dipyridyl. C6H4(H3)N.]Sr(H3)C6H^ Homologues of Pyridine. The homologues of pyridine occur with that base in the products of the distillation of bones, coal, &c. Various members of the class have been obtained synthetically. PicoLiNES. Methyl-pyridines. CgH^N; or C5H4(CH3)N. Three isomeric modifications of picoline exist, dififering according to the orientation of the CHg group in relation to the 'N, The pico- 108 METHYL-PYRIDINES. line of coal-tar is chiefly the ortho-modification (1 : 2), often called a-picoline, mixed with some meta- or/3-picoline (1 : 3).^ Although the former boils at 134° (Weidel ; 129°-130°, Lange), and the latter at 140°, they cannot be separated by fractional distil- lation, but may be isolated by taking advantage of the different solubilities of their chloroplatinates (Ber.^ xii. 2008). Lange {Ber., xviii. 3436) thinks that a-picoline is preferably separated from bone-oil by means of its sparingly soluble mercuro-chloride. Its specific gravity at 0°, compared with water at 4°, is stated to be 0*9656. The platinochloride melts at 178°, the mercuro- chloride at 167°, and the picrate at 165°. The two last salts are moderately soluble in water. y-picoline(l:4)is produced by the distillation of acrolein-ammonia, or by heating allyl tribromide with ammonia, and by the reaction of pyridine on methyl iodide. Its presence has been recognised in coal-tar. y-picoline is stated by A. La d e nb u rg {Ber., xxi. 285) to boil at 142°-5-144°-5, the specific gravity being 0*9742 at 0° C. The platinochloride melts with decomposition at 231°; the aurochloride at 205°; the mer- curo-chloride at 128°-129° ; and the picrate at 167°. These char- acters are not strictly in accordance with the observations of Lange {Ber., xviii. 3436). The picolines are metameric with aniline, CgHg.NHg, which, however, is a primary amine, whereas the picolines have the char- acters of tertiary bases. In their odour, solubility, basic properties, and characters of their salts, the picolines closely resemble their lower homologue pyridine, but have a lower density and higher boiling-point than the latter body, LUTIDINBS. C7H9K The bases of this formula may have the constitution of ethyl- pyri dines, C5H4(C2H5)N, or of dimethyl-pyridines, C5H3(CH3),N. 1 : 4 or y-e thy 1-pyri dine constitutes the greater part of coal-tar lutidine. It is a colourless liquid of '9443 specific gravity at 0°, boiling at 154°, and miscible with cold water in all propor- tions. By oxidation it yields iso-nicotinic acid. ^ A. Ladenburg {Ber., xxiii. 2688) aflfirms the existence of two )8-pico. lines; the variety from glycerol boiling at 141°*5-142° (uncorrected), and that from strychnine at 146°-149° (uncorrected). C. Stoehr {Ber., xxiii. 3151) disputes Ladenburg's conclusions, and states that the product obtained by the distillation of brucine or strychnine is not homogeneous. After purification it yields ^S-methyl-pyridine boiling at 142°-143°, identical with the synthetical product obtained by heating glycerol with acetamide and phosphoric anhydride, which also contains pyridine and )8-ethyl-pyridine. The mercuro-chloride melts at 145°-146°, and the chloroplatinate at 201°-202°. (See Ber., xxiv. 1676.) LUTIDINES AND COLLIDINES. 109 A ^-ethyl-pyridine is formed, together with its lower homo- logues, by heating glycerol with acetamide and phosphoric anhy- dride (C. Stoehr, Jour. Prac. (7/iem., [3], xliii. 153). It boils at 140°-145°, has a specific gravity at ^^ of "9751, is almost insoluble in water, and yields nicotinic acid on oxidation. Three isomeric dimethyl-pyridines have been found by Rosenberg in vitriol-tar. Of these, the 1:2:6 {a-a) isomeride is a colourless oil boiling at 142°— 143°, and having a penetrating odour resembling that of oil of peppermint. It is freely soluble in cold, but less so in hot water. The 1:2:4 (a-y) isomer boils at 157°. The 1:2:3 (a-/3) modification has not been isolated, but its presence is inferred from its product of oxidation, iso- cinchomeronic acid. Hanzsch (Annalen, ccxv. 1) has described a lutidine (C5H3(CH3)2N) boiling at 154°, obtained by distilling a mixture of lutidine-tricarboxylate with lime. A lutidine, apparently having the constitution /3,8-dimethyl-pyridine, has been prepared by D U r k p f and G d 1 1 s c h (Ber., xxiii. 1113) by eliminating COg from a dimethyl-pyridine-carboxylic acid obtained by the oxidation of a parvoline boiling at 216°-217°. It boils at 169°-170°, has a feeble, not unpleasant odour, and dissolves sparingly in cold, but readily in boiling water. The specific gravity at ^/^ is 0*9614. The mercuro-chloride crystallises in long sparingly soluble needles, melting at 170°. On oxidation it yields a pyridine-dicarboxylic acid melting at 314°-315°, from which fact, and its external characters, the authors infer it to be dinicotinic acid. COLLIDINES. CgHj^N. A. Hanzsch (Annalen, ccxv. 1 ; Jour. Ghem. Sac, xliv. 82) gives the following description of the two known modifications of collidine : — a-Collidine. Methyl-ethyl-pyridine. CsHgiCflaXCaHs)!?. /3-Collidine. j3-trimethyl-pyridine. C5H2(CH3)3N. Boiling-point, , Specific gravity at 15°, . . SolubiUty in water, . . . Behaviour on exposure to air, C8HiiN,HAuCl4, .... Addition of CrOs gives . . Mn, Co, and ¥e salts, . . AgNOa 178' '8fi3 Very slight. Unchanged. Does not melt under water. Red oil No precipitate. No precipitate. 171° ■917 More readily soluble in cold than hot. Becomes brown. Melts under hot water ; the dry salt melts at 112°. Red crystalline precipitate of (C8HiiN)2H2Cr207. Hydroxides gradually pre- cipitated. White crystalline precipi- tate soluble in hot water. 110 COLLIDINES. 0. de Goninck has described a ^-collidine boiling at 195°- 196° {Gompt Rend., xci. 296 ; xcv. 298), having a specific gravity of '9656 at 0°; and another modification, stated to be a trimethyl- pyridine, has been isolated by J. Mohler {Ber.^ xxi. 1006 ; Joiir. Chem. Soc, liv. 727) by subjecting the bases from coal-tar to frac- tional precipitation with potassium ferrocyanide. It is a colourless liquid, unchanged by exposure to air, soluble slowly but to a considerable extent in cold water, and separating again almost completely on warming. The hydrochloride forms slender non- deliquescent needles, which sublime, without melting, with partial decomposition. The sulphate forms transparent prisms melting at 203°, and the picrate long, silky needles melting at 155°-156°. Pyridine-Carboxylic Acids. Pyridine itself is an extremely stable body, resisting the strongest oxidising agents ; but its homologues yield by oxidation a series of acids in which the alkyl-groups are replaced by a corresponding number of carboxyl-groups. The pyridine-carboxylic acids derive their chief interest from the light they throw on the relationship of the natural vegetable alkaloids to the pyridine bases. Three iso- meric pyridin e-mono car boxy lie acids, CgH^N.COOH, are obtainable, exactly corresponding to the three isomeric modifica- tions of picoline (methyl-pyridine).i The same acids may also be obtained by the action of heat on the di- or tri-carboxylic acids, just as benzoic acid, CgHg.COOH, is obtained by the action of heat (and lime) on phthalic acid, CgH^.(C00H)2. One of them (nico- tinic acid) is also obtained by the action of heat on nicotine. Ptridine-monocarboxylio Acids, CgH^KCOOH,^ unite in themselves the basic characters of pyridine with those of an acid. Thus they combine with hydrochloric acid, and the resulting com- ^ The pyridine-monocarboxylic acids have the empirical formula CgHgNOg, and the same percentage composition as nitro benzene. 2 The bases from coal-tar boiling between 130° and 140" are boiled in an apparatus furnished with a reflux condenser with ten times their weight of potas- sium permanganate in 2^ per cent, aqueous solution, until the permanganate is reduced. The oxide of manganese is then filtered off, and the clear liquid con- centrated to a small bulk. It is then neutralised and treated with acetate of copper. The precipitate is separated, decomposed by sulphuretted hydrogen, and the filtrate decolorised by animal charcoal. On further concentration and cooling it deposits colourless needles of picolinic acid. The filtrate from the copper precipitate is further evaporated, acidulated with acetic acid, and treated at its boiling-point with acetate of copper. The resulting bluish-green precipitate is separated, boiled rapidly with water, and decomposed by sul- phuretted hydrogen. On evaporation, the filtrate deposits colourless crusts of isonicotinic acid. PYRIDINE-CARBOXYLIC ACIDS. Ill pound forms double salts with mercuric chloride, platinic chloride, &c. ; while, on the other hand, they form a series of well-defined crystallisable salts. The following table exhibits their more im- portant characters : — Ortho- Compound or a- Acid. Picolinic Acid. Meta-Compound or P-Acid. Nicotinic Acid. Para- Compound or y-Acid. Isonicotinic Acid. Mode of formation, Crystalline character, . Melting-point, Solubility, . . . Reaction with neutral lead acetate, Reaction with am- moniacal lead acetate, Reaction with cupric acetate, Reaction with ferrous sulphate. Characters of hydro- chloride — C6H5N02,HC1, Oxidation of a- picoline by per- manganate. Prismatic needles. 135'; sublimes in lustrous needles. Easily soluble in cold or hot water and in alcohol. Nearly insoluble in ether, chloro- form, benzene, &c. No change. No change. Slowly deposits shining laminae and needles of violet-blue col- our, and metal- lic lustre. Sol- uble in hot water. Pale reddish-yel- low coloration. Large, lustrous, ortho-rhombic prisms, which become rapidly turbid on ex- posure to air. Oxidation of /3- picoline by per- manganate, or nicotine by per- manganate chromic acid or nitric acid. Needles. 229'-231'. Sparingly soluble in cold, easily in warm water; sparingly in ether or chloro- form. Action of heat on pyridine di- or tri - carboxylic acid. Oxidation of y-picoline. Needles. (299') (809*); ■ tab- 305' sublime's in ular crystals. Sparingly soluble in water; very sparingly in ether and beii- No change. White crystalline precipitate. Pale blue-green precipitate, in- soluble in a large quantity of water. No change. Monoclinic prisms, quite permanent in the air. Green precipitate on warming. No change. Large shining crys- tals. On heating with lime, the above acids yield pyridine, just as benzoic acid yields benzene under similar conditions. The sodium salts of the a and fi acids, when treated in solution with sodium amalgam, give ofif ammonia, and yield the salt of an unsaturated acid of the fatty series, CgHgOg. Pyridine-dicarboxylio Acids. 05X13(00011)2. Of the six possible acids of this formula, all are known. They are pro- duced by the oxidation of homologues of pyridine containing two 112 PYRIDINE-DICARBOXYLIC ACIDS. substituted hydrogen atoms, and also by the oxidation of other substances. QuinoUnic Acid [the a-y8 modification] is obtained by the oxida- tion of coal-tar quinoline by permanganate, and is the analogue of phthalic acid, obtained similarly by the oxidation of nai)hthalene. It crystallises in short prisms, slightly soluble in cold water, more readily in hot water and alcohol, insoluble in benzene. It blackens when heated, and melts at about 228°, apparently being converted into nicotinic acid {Jour. Chem. Soc, xliv. 90). The acid is removed from its aqueous solution by ether. Lutidinic Add [a-y] is similarly produced by the action of permanganate on cinchonine-quinoline. It melts at 235° (219°), forming iso-nicotinic acid, is sparingly soluble in cold water, and gives with cupric acetate a pale blue precipitate. (See Berichte, XX. 127.) Dlpicolinic Acid [a-a'] melts at 226° ; Isocinchomeronic Acid [a-p] at 236°; and Dinicotinic Acid [/?-^'] at 323°. Cinchomeronic Acid [/J-y] is the chief product of the oxida- tion of quinine by nitric acid, and is also obtained, together with other products, by the similar treatment of cinchonine. It crystallises in white prismatic needles, which melt at 259° (267°), with partial decomposition, and is only very sparingly soluble, even in boiling water. It forms two classes of salts. Its most characteristic reaction is its behaviour with cupric acetate, which does not give a precipitate in the cold, but on heating the liquid becomes turbid, clearing again on cooling. On prolonged boiling, a permanent azure-blue precipitate is formed. All the dicarboxylic acids which contain a carboxyl-group in the a-position give a reddish yellow coloration with ferrous sulphate. Pyridine-tricarboxylic Acids, C5H2(C0.0H)3, are obtained by the oxidation of certain alkaloids. Thus quinine, quinidine, and cinchonidine, by boiling with an alkaline solution of permanganate, yield liydroxycinchomeronic acid, which forms orthorhombic prisms melting (with blackening) at 244° ; while berberine, when oxidised by nitric acid, yields the isomeric body berberonic acid, crystallis- ing in the triclinic system. Both acids give a deep red colour with ferrous sulphate, destroyed by a mineral acid. Pyridine-tetracarboxylio Acids, C5lI]Sr(CO.OH)4, have been obtained. Pyrtdine-pentacarboxylio Acid, C5N(C0.0H)5, forms crystals containing 2 aqua. It becomes anhydrous at 120°, and decom- poses without melting at 220°. It is freely soluble in water, and is a strong acid, resembling oxalic acid in its power of form- ing acid and double salts (Hanzsch, Jour, Chem. Soc, xliv. 85). PYRROL. 113 Pyrrol.^ C^H^N, or C^H^.NH. This associate of the pyridine bases ^ is a colourless liquid of pungent taste, and odour like that of chloroform. The specific gravity is 1*077, and boiling-point 130°-133°. It is but little soluble in water, and insoluble in alkalies, but dissolves in dilute acids, alcohol, and ether. It is indifferent to most reagents, but appears to possess feebly-marked basic properties. The only definite salt is the picrate, which forms unstable red needles melting at 71°. Pyrrol turns brown in the air, and when warmed with acids forms a red substance known as pyrrol-red, the reaction apparently occurring being: — 3C4H5N'-}-H20 = Ci2Hi4N20-hNH3. A piece of pine- wood, moistened with hydrochloric acid and exposed to the vapour of pyrrol, becomes deep red. When a cold aqueous solution of isatin is treated with pyrrol and a little dilute sulphuric acid, a heavy blue precipitate, resembling indigo, is obtained. When both reagents are dis- solved in glacial acetic acid and boiled, a deep blue solution is obtained, apparently containing the same colouring-matter. If a solution of phenanthrene-quinone in acetic acid be treated with pyrrol and a little dilute sulphuric acid, a brown precipitate is formed, which dissolves in chloroform with a beautiful violet- red colour. When an aqueous solution of benzo-quinone is treated with pyrrol and dilute sulphuric acid, a dark green precipitate is formed, insoluble in ether. These reactions indicate the close relationship between pyrrol and thiophene, which itself has the constitution of a thio-furfuran. Many of the reactions of pyrrol are also produced by carbazol, which is an i m i d o - diphenyl. Indole has a constitution between pyrrol and carbazol. Thus : — Pyrrol, C4H6N. .CH:CH. {:C1;C^:}- { .CH:CH Furfuran, C4H4O .CH:CH .CH:CH Thiophene, C4H4S. '.CH:CH Indole, CgHyN. .CH:CH. K^jj {: Th {: CH:CH. 4U. Carbazol, C12H9N. ] Diphenylene Oxide. Thioiiaphthene, CgHgS. s - Pyrrol has been obtained synthetically by passing acetylene and ammonia through a red-hot tube, and also by the dry distillation of the ammonium salts of mucic and saccharic acids. ' The proportion of pyrrol contained in coal-tar is very small. It is best Drepared by shaking bone-oil with dilute sulphuric acid and fractionating the insoluble portion. The fraction boiling between 100° and 150° is heated VOL. III. PART II. H 114 lODOL. Two isomeric methyl-pyrrols exist in bone-oil,^ resides a dimethijl- pyrrol, boiling at 165°, which has also been obtained synthetically, and closely resembles pyrrol. In the homologues of pyrrol occurring in bone-oil, substitution has always occurred in the C^H^ group, but by the action of alkyl iodides on potassium-pyrrol substitution of the hydrogen of the NH group can be effected. Tetraiodo-pyrrol, C^I^NH, has been recently introduced into medicine under the name of " i o d o 1." It is prepared by the action of iodised potassium iodide on pyrrol, and forms a tasteless, pale yellow, crystalline powder, having a faint thymol-like odour. It is unchanged at 100°, but gives off iodine vapour at a somewhat higher temperature. lodol is nearly insoluble in water, but readily in ether and chloroform. It dissolves in three parts of alcohol, and the solution is precipitated by adding water, but not by glycerin, lodol contains 90 per cent. of. iodine and possesses antiseptic and local anaesthetic properties analogous to those of iodoform, over which its slight odour and freedom from toxic properties give it the preference. lodol can be recognised by the green colour of its solution in sulphuric acid, and by the bright red colour produced when an alcoholic solution is warmed with nitric acid. QUINOLINE AND ITS ALLIES. The interesting base which gives its name to the quinoline series bears the same relation to naphthalene that pyridine bears to ben- zene ; that is, it is derived by the substitution of an atom of nitro- gen for one of the CII groups of naphthalene (see foot-note, Yol. II. page 507) :— Pyridine, . . C5H5N Benzene, . . . CgHg Naphthalene, . . CjoHg Quinoline, , . CgH^N ■with a large excess of solid caustic potash in a reflux apparatus until the whole is fused, when any unchanged oil is separated and the crystalline mass of potassium pyrrol, C4H4KN, is powdered, and after being washed with ether is treated with water and distilled with steam, when the pyrrol is regenerated. 1 To isolate these methyl-pyrrols, the fraction of bone-oil boiling between 1.40° and 150° is converted into the potassium derivative, and this is heated to 200° in a stream of carbon dioxide. Two isomeric homopyrrol- carboxylic acids are formed. The o-acid melts at 169° "5, and forms a lead salt very soluble in water, while the )8-acid melts at 142°'4, and forms a nearly insoluble lead salt. On distilling the respective acids with lime, the corresponding o- and )8-homopyrrols are regenerated. The first boils at 148° and the latter at 143° at 743 mm. pressure. QUINOLINE SERIES. 115 QuinoHne may be represented by the following constitutional formulae. Where substitution occurs in the pyridine-nucleus, a, ]8, and 7 (or P-1, -2, and -3) products are obtained, while substitu- tion in the benzene-nucleus yields ortho-, meta-, para-, and ana- derivatives (or B-1, -2, -3, -4), according to the position of the substituted hydrogen atom. CH en Fig. 2. Fig. 3. Just as two isomeric naphthols exist, so two isomeric quinolines are theoretically possible, and appear to have been obtained. Thus the quinoline obtained by distilling quinine, cinchonine, and other alkaloids with potash (fig. 2) appears to dijQfer in some of its re- actions from the quinoline contained in coal-tar, which is often called 1 e u c o 1 i n e (fig. 3)., On the other hand, Hoogewerff and Van Dorp {Jour. Chem. Soc, xliv. 89) contend that the quinolines obtained from both sources are identical. A whole series of higher homologues are produced, together with, quinoline, on distilling alkaloids with caustic potash.^ y-methyl quinoline or lepidine, C^q{CJ{^^, the first member of the series, boils at 266°. Of the next member, despoline, CiiH^^N, and the still higher homologues, very little is known. A parallel series of bases have been found in coal-tar and shale- oils. They are obtained from the fractions of the bases boiling above 200°, and hence distil after the pyridine bases have passed over. Quinaldine, or a-methyl-quinoline, C9Hg(CH3)I^, boils at 239°, and sometimes forms 25 per cent, of coal-tar quino- line. It is a colourless liquid (also obtainable synthetically), the oxidation of which yields either a benzene or a quinoline derivative, according to the nature of the oxidising agent.^ IridoUne, isomeric with quinaldine, and probably identical with lepidine, is also con- * If the distillation be conducted in presence of copper oxide, the quinoline obtained is almost free from higher homologues. ^ When quinaldine is heated with amyl iodide it forms the compound CjH6(CH3)(C5Hji)NI, which on heating with caustic potash is converted into a cyan in e, CggHsjNI (page 118). A similar body is obtainable from lepi- dine, and a mixture of the two has been used for dyeing silk, but the colour is very fugitive. When heated with phthalic anhydride, quinaldine reacts to form a body of the phthalein class known as quinoline-yellow (see Vol, III. Part I. page 174). 116 QUINOLINE SERIES. tained in coal-tar. It boils between 252° and 257°, and yields a crystallisable nitrate, chromate, and hydrochloride. From the acid tar produced in the purification of shale-oil, Robinson and Goodwin {Trans. Roy. Soc. Edin., xxviii. 561; xxix. 265) obtained the following bases of the quinoline series. Base. Formula. Boiling-Point, ' C. Tetracoline, C10H13N 290-295 Pentacoline, C13H15N 305-310 Hexacoline, . , , . C14H17N 325-330 Heptacoline, C15H19X 345-350 Octacoline, .... CigHoiN 360-365 Quinoline, Chinoline. CgH-N. This base is formed by distilling quinine, cinchonine, or strych- nine with aqueous potash, and by other interesting reactions ; but is best prepared by shaking together nitrobenzene (48 parts), aniline (76 parts), glycerin (240 parts), and sulphuric acid (200 parts). "When the aniline sulphate has dissolved, a reflux condenser is fitted to the flask, which is heated to 130° till reaction sets in, when the flame is removed. In about three hours, or when action is at an end, the product is cautiously diluted with water, and boiled to get rid of traces of nitrobenzene, after which lime or caustic soda is added, and the quinoline and unchanged aniline distilled over in a current of steam. The oil obtained is separated from the aqueous layer, dehydrated over caustic potash, and fractionally distilled, whereby a separation of the bases is eff'ected tolerably readily, aniline boiling at 184°, and quinoline at 239°. To purify the latter it is again fractionally distilled, and boiled with weak chromic acid mixture (to oxidise any aniline) ; or the quinoline is dissolved in six parts of water, and strong sulphuric acid added in the exact quantity necessary to combine with the base. After cooling, the liquid is filtered, and the insoluble acid sulphate washed with alcohol till snow-white, and then decomposed by potash.^ • ^ The reaction in the foregoing reaction may be written thus : — 2C6H^N + CgHgNOa + 3C3H803 = 3C9H7N + NH,0 . The change is undoubtedly due to the formation of a c r o 1 e i n, C3H4O, from the glycerin, and the reaction of this with aniline to form acrolein-aniline, with simultaneous oxidation by the nitrobenzene : — CsHgOa + CgHgNHg + = C9H7N + 4H2O . The homologues of quinoline may be obtained in an analogous manner, and by QUINOLINE. n 7 Quinoline is a colourless mobile liquid, having a penetrating and peculiar taste, and an after-taste slightly resembling peppermint- oil. It has a faint aromatic odour, like that of bitter-almond oil. Quinoline evaporates completely but slowly at the ordinary tempera- ture, so that the grease-spot formed by it on paper is not permanent. It boils at 238°-239°, according to most observers; 231°*5, according toSpaleholtz; and 241°*3, according to Kretschy. Its specific gravity is stated to be I'OSl at 0° C, and 1*094 at 20° C., compared with water at the same temperature. Quinoline is very sparingly soluble in cold water, but more freely so in hot. It is miscible in all proportions with alcohol, ether, carbon disulphide, and fixed and volatile oils ; and is also easily soluble in chloroform, amylic alcohol, benzene and petroleum spirit. On exposure to air, quinoline becomes resinified. Quinoline has well-marked basic characters, and forms an extensive series of salts, most of which are crystallisable and deliquescent. It precipitates ferric and aluminium solutions, and at a high tem- perature decomposes ammonium salts. Quinoline can be titrated fairly accurately with standard acid, it methyl-orange be employed' as an indicator. Reactions of Quinoline and its Salts. Quinoline salts in aqueous solution are precipitated milky white- by caustic alkalies and ammonia, the precipitate being somewhat, soluble in excess. From the alkaline liquid, the quinoline can be- readily extracted by ether, chloroform, or petroleum spirit. Iodised iodide of potassium gives a reddish-brown precipitate even in dilute solutions of quinoline salts (1 in 20,000). Potassio- mercuric iodide only precipitates quinoline from tolerably strong solutions (1 in 3000), the precipitate being yellowish white and amorphous, but converted into delicate amber-yellow needles on addition of hydrochloric acid. This reaction is characteristic. Phosphomolybdic acid, in presence of nitric acid, produces a. yellowish-white precipitate in quinoline solutions. Potassium ferrocyanide colours solutions of quinoline salts reddish,, and on addition of hydrochloric acid a reddish-yellow amorphous precipitate is thrown down, if the liquid be not too dilute. Quinoline is precipitated by picric acid, but not by tannic acid or ferric chloride; and its salts, in the solid state, yield no colour- reactions with nitric acid or strong sulphuric acid, either alone or in association with oxidising agents. With potassium bichromate, if carefully added, quinoline salts em]iloying derivatives of aniline or its homologues, quinoline substituted in the benzene-ring may be obtained. 118 QUINOLINE. yield a precipitate of delicate dendritic crystals of the bichro- mate (CQiij^)Ii^,Crfi^, said by Donath to be soluble in excess of the reagent. Quinoline bichromate melts at 165° C. When quinoline is heated with sodium, diquinolyline, CgHgN.CgHgN, analogous to dipyridyl and diphenyl, is formed. When polymerised, quinoline yields yellow needles of diquino- line, (C9H7N)2. When quinoline and amyl iodide are boiled together for a short time, they combine to form a crystalline body containing 09X17(0511^1)^1. If the product be dissolved in boiling water, and tlie solution filtered and boiled with caustic soda or ammonia, avoiding excess, a blue colouring matter is formed, which, on allow- ing the liquid to cool, is precipitated, leaving the solution nearly colourless. The separated substance, called c y a n i n e, is a basic body crystallising in green plates, having a metallic lustre. It is nearly insoluble in cold water, but dissolves in alcohol to form a rich purplish blue solution, which dyes silk blue. The foregoing reaction, as also that with potassium bichromate, is said not to be obtainable with the quinoline (leucoline) of coal-tar. Quinoline possesses powerful antiseptic properties. 0'2 per cent, of the tartrate is said to completely prevent the lactic fermentation of milk, the decomposition of urine and gelatin, and the develop- ment of bacteria in cultivation-fluid. Even in concentrated solu- tion it does not coagulate albumin, and in the proportion of 1 per cent, it completely destroys the coagulability of the blood. On the other hand, quinoline is remarkably inactive to yeast-cells, and does not atfect the alcoholic fermentation, even when present in considerable quantity. Quinoline has been used in medicine as an antipyretic, the adult dose of the tartrate being from 7 to 1 2 grains. It is said by some not to produce any unpleasant after-effects, but by others to cause irritation of the stomach and collapse. It is not found in the urine of those who have taken it internally. Commeixial Quinoline is often very impure and quite unfit for medicinal use. 0. Ekin (Pharm. Jour., [3], xii. 661) has described a specimen which had a deep brown colour and an odour like oil of bitter almonds. On treating it with hydrochloric acid a large proportion remained insoluble, and was evidently uncon- verted nitrobenzene, while the soluble part gave the reactions of aniline. Cinchonine-quinoline often contains lejndine. Such samples give the cyanine reaction (see above) with amyl iodide and caustic alkali. The salts of quinoline should be completely soluble in water, QUINOLINE DERIVATIVES. 11& and the free base in a slight excess of hydrocliloric acid. The neutral solution should be free from bitter taste (which indicates the presence of impurity derived from cinch onine), and should not give a coloured precipitate with caustic alkalies. Quinoline Tartrate^ {Qi^,j^\{C^^O^^, is now used extensively in medicine. It melts at 125° C, and possesses the advantage of being permanent in the air, whereas most of the salts of quinoline are deliquescent. It dissolves in 80 jDarts of cold water, in about 150 parts of rectified spirit, and in 350 parts of ether. It produces much the same effects as sulphate of quinine, and is given in similar doses, but is far lower in price. Quinoline Hydrocldoride, C9HyN,HC1, melts at 94° C, and sub- limes unchanged. It dissolves in water, alcohol, and chloroform, and sparingly in cold ether and benzene. Tetrahydroquinoline. e,H„N;orCA{CW| When quinoline is acted on by nascent hydrogen, it is first con- verted into dihydroquiiioline, CqHqN, a solid body melting at 161°, and subsequently into tetrahydroquinoline, which is a liquid boiling at 245°. Both these reduction-products yield nitrosamines, and can be alkylated, and hence are secondary bases. Tetrahydroquinoline possesses stronger antipyretic characters than quinoline itself, and this property is exhibited still more strongly in certain of its derivatives, several of which have received some api^lication in medicine (see below). Antipyretics allied to Quinoline. A considerable number of new substances related to quinoline, and mostly allied to tetrahydroquinoline, have been recently intro- duced as febrifuges and antipyretics. Some of these are very powerful in their action, and ap})ear likely to receive a permanent place in medicine ; but they are not periodics, and cannot be sub- stituted for quinine in cases of ague or intermittent fevers. The following are the most important of the antipyretics derived from or related to quinoline.^ il/-KAiROLiNE is the acid sulphate of a base having the constitu- ^ Other antipyretics are described in the sections on anilides, amidophenols, antipyrine, &c. Many interesting facts relating to and relationships of the antipyretics have been collated by T. S. Dymond and an anonymous German author {Pharm. Jour., [3], xvii. 886-895). A fuller and more recent description of them is given in a series of articles on " Modern Materia Medica," contributed by H. Helbing to the British arid Colonial Druggist, 1891, and since published in a separate form. 120 KAIRINES. tion of methyl-tetrahydro-quinoline, C9Hjq(CH)3N, obtained by reducing quinoline by tin and hydrochloric acid, and reacting on the resulting tetrahydroquinoline with methyl iodide. ^-Kairoline had a similar constitution, but contained ethyl, C2H5, instead of the methyl-group. ilf-KAiRiNE is the hydrochloride of Hydroxy-tetra- hydro-methyl-quinoline, p XT /rkTT\ / CHg.CHg. ] The corresponding ethyl-derivative ^Q^zK^^) ' I N(CH3).CH2. I is known as A-Kcdrine. On adding a caustic alkali to the aqueous solution of a kairine, the penetrating characteristic odour and bitter taste of the free base are easily recognised, while the alkaline solution rapidly becomes coloured and deposits a brown humus-like substance. When the aqueous or alcoholic solution of a kairine is treated with an oxidising agent, such as potassium bichromate and an acid, it gives a series of colours ranging from violet-blue to purple, or sometimes greenish. Without the addition of an acid, the solution becomes dark purple, and on standing a violet precipitate is formed, which dissolves in alcohol with black colour. A drop of ferric chloride, added to a dilute and neutral solution of kairine, instantly produces a violet coloration, rapidly changing to brown, with precipitation. An excess of ferric chloride added to a strong solution of kairine produces a nearly black precipitate. Sodium nitrite and dilute sulphuric acid produce an orange or red colour in kairine solutions. Potassium ferrocyanide gives a voluminous precipitate, and phosphotungstic acid a pale yellow precipitate. The kairines act as powerful antipyretics. Their use is almost obsolete, as their action is somewhat uncertain ; and they are said to be liable to produce vomiting, cyanosis, and collapse. Thalline is the commercial name of another antipyretic, meta- meric with m-kairine, and having the constitution of a salt of tetrahydro-paraquinanisol : — CA(0.CH3):{CW| Thalline is prepared by heating paramido-anisol and paranitro- anisol with glycerin and sulphuric acid, and reducing the product with nascent hydrogen. Thalline base crystallises in large colour- less prisms, having a bitter, saline, and pungent taste. It melts at 42° C, and is sparingly soluble in water, but readily in alcohol, ether, chloroform, or benzene. Thalline Sulphate, (CioHi3NO)2H2S04-|-2H20, is the most com- mon variety of commercial " thalline." It occurs as a yellowish- white, granular or crystalline powder, having a bitter, aromatic taste. THALLINE. 121 and a faint odour resembling anise and meadow-sweet. It dissolves in seven parts of cold water, but only sparingly in alcohol, and the solutions become darker on exposure to light. A very dilute aqueous solution of commercial thalline gives with ferric chloride a yellow coloration, changing to emerald-green (destroyed by reducing agents), and passing in a few hours to deep red. The reaction is extremely delicate. A green colour is also produced by auric chloride, argentic nitrate, mercuric nitrate, chlorine-water, &c., and, in acid solution, also by solution of bleaching powder and potassium ferricyanide. Strong sulphuric acid dissolves thalline sulphate without coloration, but on addition of nitric acid the liquid becomes deep red, and immediately afterwards yellow-red. Fuming nitric acid colours a dilute aqueous solution reddish. Sulphuric acid and sugar give a red coloration. Iodine colours the solution dark brown, then dingy green. Ammonia forms a white precipitate of the free base, readily taken up by ether on agitation. If not too dilute, solutions of thalline sulphate yield precipitates with the general reagents for alkaloids. If to an aqueous solution of /3-naphthaquinone a small quantity of the solution of a thalline salt be added, and then a drop or two of caustic soda solution, a fine cherry-red coloration is produced, becoming more brilliant on adding nitric acid. The colouring matter is extracted by ether or chloroform. Thalline Tartrate occurs in commerce as a yellow- white crystal- line powder. It dissolves in ten parts of cold water, and the solution gives the same reactions as the sulphate. In alcohol it is very sparingly soluble. The salt contains 52*2 per cent, of thalline. The salts of thalline become altered by exposure to light. Thalline salts are powerfully antipyretic, and have been em- ployed in yellow fever. They cause profuse perspiration, and are apt to produce depression, &c. Hence their internal use is practically obsolete. Thalline acts as a direct blood-poison, its antithermic properties being due to the destruction of the red corpuscles. It has found considerable application in the treatment of gonorrhoea. The sulphate is official in the German Pliarmaccypoeia of 1890. Exhibition of thalline causes a dark coloration of the urine. A derivative, which also gives a green colour with ferric chloride, but differs from thalline in being extracted by agitating the acidulated urine with petroleum spirit, should first be removed, and then the un- altered portion of the thalline can be isolated by rendering the urine alkaline with ammonia, and agitating with ether or benzene. Very small quantities of thalline can in this way be recognised in urine. Ethyl-thalline, CioIIioON(C2H5), is produced by heating ordi- nary thalline with ethyl iodide. 122 QUINAZOLINES. Thermifugin is a name given to the sodium salt of methyl- trihydroquinoline-carboxylic acid : — (COOKa)CA:{SfdHjcHj Quinazolines. By the replacement of one of the CH groups of quinoline by N, bodies are obtained which bear the same relationship to quinoline that the azines bear to pyridine. Thus : — Ortho-azine (Oiazine). ^{:cH."cH>H Meta-azine (^Miaziue). Quinoline. „f:CH.CH.- CH Ortho-guinazoline (Pheuoiazine). CH Para-azine (Piazine). :CH.CH: .CH:CH. |:CH.CH:| ^ \ .CH:CH. I ^^ l-CeH,. I Meta-quinazoliru (Pheumiazine) . Para-quinazolin (Phenpiazine). CH A substituted meta-quinazoline having the constitution of a phenyl-dihydrophenmiazine : — ^f:CH.N(C,H,).| has recently acquired some practical interest as the base of "o r e x i n," a preparation said to have valuable tonic, stomachic, and appetising properties, on which, however, some doubt has been thrown {Pharm. Jour., [3], XX. 709, 825, 977 ; xxi. 43). The usual dose of orexin is from 2 to 10 grains. Orexin, which occurs as a hydrochloride having the composition Ci4nj2N2,HCl+2H20, is prepared by reacting on the sodium- derivative of formanilide by ortho-nitrobenzyl chloride, according to the equation: — Na(CHO).N.C6H5 + Cl.CH2.C6H4.N02-NaCl + CHO.N(C6H5).CH2.C6H4.N02 The nitrobenzyl-formanilide, on reduction with tin and hydro- chloric acid, forms the closed chain compound which is the base of orexin : — OREXIN. 123 Orexin (hydrochloride) crystallises with 2H2O in white needles, melting at 80°. When kept under an exsiccator for some time they become anhydrous, and then melt at 221°. Orexin has a bitter taste, and somewhat intense, burning after-taste. The powder induces violent sneezing. Orexin dissolves readily in water (13 parts) and alcohol, but not in ether. On adding an alkali to the aqueous solution the free base is separated as a white flocculent pre- cipitate readily soluble in ether and chloroform.^ A solution of orexin yields with mercuric chloride a white precipitate soluble in hot water, and redeposited in white needles on cooling. Potassium bichromate gives a yellow precipitate soluble on heating, and redeposited on cooling in golden yellow needles. Bromine-water is decolorised with formation of a yellowish amorphous precipitate. Orexin reduces potassium permanganate in the cold. On heating orexin in a test-tube with about twice its measure of zinc-dust, the strong characteristic odour of phenyl-isonitrile is produced. On treating the residue with hydrochloric acid, and adding bleaching-powder solution to the filtered liquid, a blue coloration is obtained, owing to the previous formation of aniline (compare page 45). ACRIDINE AND ITS ALLIES. Acridine and its isomer phenanthridine bear the same relation to anthracene and phenanthrene respectively that quinoline bears to naphthalene, and pyridine to benzene (compare page 39). The following formulae show their constitution and relationship to anthracene and phenanthrene : — CeH,:|?|:C.H, { WHjl} Anthracene. Phenanthrene. CeH.:|?}:CA ^^'^ }] Acridine. Phenanthridine. Acridine. C13H9N Acridine has been prepared synthetically by heating concentrated ^ The base sometimes separates as an oil, which afterwards crystallises. 124 ACRIDINE. formic acid or chloroform with diphenylamine and zinc chloride/ and also by various other reactions. Acridine is contained in coal-tar, and may be extracted from the fraction boiling between 300° and 360°, or from crude commercial anthracene, by agitating it with dilute sulphuric acid, precipitating the acid liquid with potassium chromate, purifying the acridine chromate by recrystal- Hsation, precipitating the base by ammonia, and recrystallising it from hot water. The hydrochloride may also be employed for the purification of acridine. Acridine forms colourless or brownish-yellow rhombic prisms, of very pungent odour and burning taste. It melts at 107°, sublimes in broad needles at about the same temperature, boils unchanged at 360°, and distils with the vapour of water. Acridine is very slightly soluble in cold, but more readily in boiling water, crystallising on cooling in long needles. It is readily soluble in alcohol, ether, benzene, carbon disulphide, &c. Dilute solutions of acridine (and its salts) exhibit a strong blue fluorescence, which is green in more concentrated solutions, and disappears if they are very strong. Certain reactions of acridine solutions with reagents are described on page 126. The most characteristic property of acridine is its intensely irritating effect on the skin and mucous membrane. Violent sneezing and coughing are produced by inhaling the smallest particle of the dust or vapour. The base and its salts attack the tongue even in minute quantities, and even very dilute solutions cause acute sting- ing when applied to the tongue or skin. Acridine has been employed as an insecticide, and compositions containing it have been patented for coating the bottoms of vessels. It is highly probable that the preservative properties of coal-tar creosote oil are partially due to the presence of acridine. Acridine is a very stable substance. Sulphuric acid has no action upon it, except at a very high temperature, and caustic potash does not react below 280°. Concentrated nitric acid con- verts acridine into nitro-derivatives. Most other oxidising agents act with difficulty or not at all on acridine, but by the action ^ Acridine is best obtained by heating a mixture of one part each of chloro- form, diphenylamine, and zinc or (preferably) aluminium chloride, with one-half part of zinc oxide, for seven or eight hours, under pressure, to 200°-210'' C. The product is boiled with concentrated hydrochloric acid, the filtered liquid poured into water, the liquid again filtered, the acridine precipitated from the solution by ammonia, and recrystallised from hot water (Fischer and K r n e r, Ber.^ xvii. 101). The reaction is as follows ; — (C6H5)2NH + CHCl3 + ZuO-C,3H,N,HCl + ZnC]2 + H20. SALTS OF ACRIDINE. 125 of potassium permanganate it has been converted into quinoline- dicarboxylic or acridinic acid. Acridine is a tertiary amine. It unites with methyl iodide. Salts of Acridine. Acridine is a feeble base. It forms no carbonate, and its salts are more or less decomposed by boiling with a large quantity of water. Acridine HydroMoride, CigHgNjHCl, forms yellow plates. The solution in water exhibits a bluish-green fluorescence, and gives a yellow crystalline precipitate of the mercwo-chloride, (Ci3H9N,HCl)2HgCl2, on adding mercuric chloride. With platinic chloride it yields the cJiIoroplatinate, (Ci3HgN)2H2PtClg, in minute, sparingly soluble, yellow needles. Acridine Nitrite, (Ci3H9N)2,HN02,H20-i-2 aqua, is obtained as a yellow flocculent precipitate on mixing solutions of acridine hydro- chloride and sodium nitrite. It forms long, yellow, silky needles, melting at 151°, somewhat volatile with steam, slightly soluble in ether or cold water, more readily in hot water, and very soluble in alcohol. Acridine Sulphite, (Ci3HgN)2,H2S03, is precipitated in yellowish- red or brDwnish needles, very slightly soluble in water, on mixing solutions of sodium sulphite and acridine hydrochloride, and adding hydrochloric acid.^ Acridine Picrate, C;^3ngiS',CgH3(N02)3. This compound is ob- tained as a canary-yellow precipitate, consisting of minute, yellow, prismatic needles, which melt with blackening at 208°. It is almost wholly insoluble in cold, and is partially decomposed by boiling water ; it is but slightly dissolved by alcohol or benzene even when boiling. Acridine has been suggested by Anschiitz {Ber., xvii. 438 ; Jour. Soc. CJiem. Ind., iii. 234) as a suitable reagent for the determination of picric acid, the hydrochloride being used as a precipitant for metallic picrates, and a solution of the free base in, benzene for the picric acid compounds of hydrocarbons. HtDROACEIDINE. DiHYDRO acridine. CgH^ \ Nvt ( ^6^4" This substance is formed (together with a white substance in- soluble in alcohol) by the reduction of acridine in alcoholic solution by sodium-amalgam. It forms prisms melting at 169°, insoluble in water, slightly soluble in cold alcohol, very soluble in hot alcohol or ether. It dissolves in concentrated sulphuric acid, and is pre- cipitated unchanged on dilution with water. Argentic and cupric ^ Before adding acid, the liquid contains the compound C13H9N NaHSOs, which forms colourless easily soluble prisms. 126 PHENANTHRIDINE. oxides reconvert it into acridine. Hydroacridine is the analogue of piperidine (page 106) and tetrahydroquinoline (page 119). f C,H,.CH: )] tCeH,.N: |f PhEN ANTHRIDI NB. ' 'V Phenanthridine is isomeric with acridine, bearing the same relation to phenanthrene that acridine bears to anthracene (P i c t e t and Ankersrait, Ber., xxii. 3339 ; Jo7ir. Soc. Chem. Ind., ix. 280). It melts at 104° and boils about 360°. Phenanthridine presents the closest resemblance to acridine, the chief difference being in its behaviour with reducing agents, for, while acridine yields on reduction a non-basic derivative, phenanthridine gives a hydro-base, which crystallises from alcohol in white needles melting at 100°, and is converted by nitrous acid into a nitros- amine. The mercuro-chloride of acridine melts at 225°; the corresponding compound of phenanthridine at 190°. On adding sodium sulphite to a solution of the hydrochloride of acridine, a pre- cipitate of reddish-brown needles is produced, while phenanthridine yields no precipitate. VEGETABLE ALKALOIDS, The term " alkaloid " was originally applied to the various basic principles existing naturally in plants. As the number of known animal bases increased in number, it became necessary to describe the plant-bases as " vegetable alkaloids " to distinguish them from the alkaloids of animal origin. But with the advance of synthetical chemistry, and the study of coal-tar products, an enormous number of new bases were prepared, and the restriction of the term alka- loid to the natural plant-bases became still more difficult. Dis- coveries in recent years have clearly established the fact that many of the plant-bases are related to pyridine or quinoline, and several of the alkaloids have been obtained by actual synthesis from pyridine or its derivatives. In other cases, such as cinchonine and strychnine, the actual synthesis of the alkaloid has not hitherto been effected, but the relationship of the bases to pyridine and quinoline is not less certain. On the other hand, some of the plant-bases stand in much closer relation to uric acid and the bases found in the animal organism than they do to the other plant- bases. Thus caffeine and theobromine are undoubtedly uric acid derivatives, while quinine and morphine show no relation to uric acid, being evidently pyridine derivatives. K n i g s has proposed to restrict the term " alkaloid " to bases belonging to the second of these classes, and to define alkaloids as " those organic bases found in the plant kingdom which are pyridine derivatives," and it seems probable that this proposal will gradually be adopted, at least in effect. With the exception of a limited number of volatile alkaloids {e.g., nicotine, conine, sparteine), the plant-bases contain oxygen in addition to carbon, hydrogen, and nitrogen. They are analogues of ammonia, not ammonium bases ; that is, they combine with hydrochloric acid and other acids without elimination of water. The names of the alkaloids are now usually made to terminate in ine, and it is very desirable that this termination should be 128 CHARACTERS Oi ALKALOIDS. strictly confined to bodies of a basic nature.^ The termination ia is still employed for a few of the vegetable alkaloids (e.g., morphia), and by some American writers for certain other alkaloids. The class of bodies known as g 1 u c o s i d e s — some of which are described in an appendix to this chapter, as, from an analytical point of view, they present some similarity to the alkaloids — should receive names having the termination in. The true vegetable alkaloids or plant-bases are very numerous. Many of them are but imperfectly known, while others (e.g., morphine, quinine, strychnine) have been studied very completely. The alkaloids as a class are found in all parts of plants, though in some cases the occurrence of particular alkaloids is curiously restricted to certain portions of the plant. Similarly, many of the alkaloids have been met with only in plants of a particular genus or family, and in some cases appear to be characteristic of a single species.2 The vegetable alkaloids are in many cases intensely poisonous {e.g., aconitine, veratrine, strychnine), while others, as the alkaloids of coffee, cocoa, and cinchona bark, produce characteristic physio- logical effects. The large majority of them have a bitter taste. With the exception of the non-oxygenated volatile bases, nearly ^ The misuse by chemists of the termination ine has caused great confusion, which its employment to designate indefinite commercial products has increased. There is no excuse for writing htuzire, paraffme, naphthaline or gelatme ; and glycerine is also an undesirable title. The recommendations on nomen- clature made by the Publication Committee of the Journal of the Chemical Society deserve more attention than they have hitherto received. 2 J. M. M a i s c h {Pharm. Jour. [3], xxi. 982 ; from Amer. Jour. Pharmacy) states that " among the acotyledons it is almost exclusively the class of fungi which in its different groups produces alkaloids, quite distinct, as a rule, in com- position and effect, from those generated within the living tissue of phanerogams. Such alkaloids are in nearly all cases confined to a single species, genus or tribe, and only in rare instances have been met with in several orders. Thus berberine exists in plants of the Ranunculacece, Anonacece, Menispermacece, Berberidacece, Eutacece, and Leguminosece ; and caffeine in the orders of Eubiacece (cofiee), Ternstromiacece (tea), Sapindacece (guarana), Sterculiaeece (colo and cacao), and in Ilidnece (mate, &c.). But colchicine has only been observed in colchicum ; veratrine and j e r v i n e in veratrum ; piperine in certain peppers ; quinine and allied alkaloids in cinchona and remijia ; strychnine and b r u c i n e in strychnos ; mor- phine and congeners in opium, and one or two of these compounds also in other poppies; sanguinarine in a few Papaveracece ; pilocarpine, physostigmine, and cocaine (?), each only in a single species; aconitine and near relatives in several aconites ; n i c o t i n e in species of tobacco, &c. " The mydriatic alkaloids of the Solaruiceoe are widely distributed throughout the order. CHARACTERS OF ALKALOIDS. 129 all the vegetable alkaloids are solid at the ordinary temperature. They are in most cases practically fixed, though caffeine and a few others may be sublimed. Many of the vegetable alkaloids are powerfully alkaline in reaction, neutralise acids perfectly, and form well-defined and crystallisable salts. In other cases the basic character is only feebly marked, no acetates existing, and even the compounds with the stronger acids being decomposed by mere dilution with water. Except the volatile bases, the vegetable alkaloids are, with few exceptions {e.g.y curarine, colchicine), very sparingly soluble in water, and are consequently precipitated, more or less perfectly, on adding caustic potash or soda to the solutions of their salts. In some cases the precipitated alkaloid is soluble in excess of the precipitant. The plant-bases are nearly all dissolved by alcohol (except rhoeadine and pseudoraorphine), and, as a rule, with great facility. The salts of the alkaloids are usually more soluble in water than the bases themselves, and, as a rule, dissolve also in alcohol. This is true of the sulphates and other classes of alka- loidal salts, the metallic analogues of which are not soluble in alcohol. Certain classes of double salts of the alkaloids (e.g., chloro- platinates, mercuro-iodides) are, as a rule, very insoluble in water (compare pages 138, 143). Solvents immiscible with water differ considerably in their action on alkaloids. The free bases are for the most part soluble, especially in chloroform and amylic alcohol, but in the great majority of cases the alkaloidal salts are insoluble in such menstrua. As, however, the salts of the alkaloids of low basic character are decomposed by excess of water, the solutions of these salts often behave with immiscible solvents in the same manner as the free bases (compare pages 158, 159). Classification of Alkaloids. The plant-bases are conveniently studied in groups, as it is found that the alkaloids of a certain order or family of plants present more or less general resemblance in properties and com- position. Thus the various alkaloids of cinchona bark, of opium, of the aconites, &c., present close analogies among themselves. Other alkaloids do not readily admit of being thus grouped, and when of sufficient importance wiU be described in separate sections. In describing the plant-bases the following general arrangement will be adopted : — The general reactions and methods of extracting and purifying alkaloids as a class will first be considered, after VOL, III. PART n. I 130 TITRATION OF ALKALOIDS. which the existing knowledge of their constitution will be dis- cussed. The non-oxygenated volatile bases will then be described. Then will follow sections on the more important saponifiable alkaloids, such as the aconite and mydriatic alkaloids, and the bases of coca. The opium bases will be next considered, and then strychnine and its allies. The cinchona bases will be treated in the next section, which will be followed by one on catFeine and its allies. Such of the alkaloids as have not been described under any of the foregoing classes, and which are of sufficient importance, will then be described. In an appendix to the chapter some of the more important vegetable bitter principles of non-basic character will be shortly described. GENERAL REACTIONS OF ALKALOIDS. The plant-bases present more or less general resemblance in their behaviour with certain reagents, and hence their general reactions are classified in the following sections. Reactions of the Alkaloids with Acids. As bodies of basic character, the alkaloids combine with acids to form salts, which in many cases are crystallisable and more or less characteristic. They are mostly soluble in water and alcohol (in- cluding the sulphates), but insoluble in chloroform, ether, &c. Certain of the salts of the alkaloids are sufficiently insoluble to allow of the precipitation of the bases for purposes of determina- tion. Instances of this occur with the picrate (berberine, cincho- nine, quinine), acid tartrate (cinchonidine), hydriodide (quinidine), chromate (strychnine), hydroferrocyanide (strychnine), periodide (quinine, atropine), chloroplatinate (berberine), aurochloride {aconitine), and mercuro-iodide (strychnine, emetine, colchicine). Titration op Alkaloids. — In their behaviour with indicators of neutrality, the alkaloids present some remarkable dilBferences of behaviour from inorganic bases. The neutral salts of strychnine, quinine, morphine, codeine, conine, nicotine, and other strongly basic alkaloids, are without action on litmus, and these alka- loids can be titrated with standard acid and litmus, just like the inorganic bases, except that their high combining weights intensify the effect of the errors of manipulation. Some of the feebler alkaloids, including narceine, narcotine, and papaverine, have no action on litmus, their salts behaving exactly like a corresponding amount of free acid. The salts of the alkaloids with mineral acids are generally TITRATION OP ALKALOIDS. 131 neutral to methyl-orange, which indicator can therefore be used to detect and determine any free acid present.'^ On phenolphthdlein the great majority of the alkaloids have no action. Hence, after neutralising any free acid with the help of methyl-orange, the acid in combination with the alkaloid present can in most cases be ascertained by titration with standard alkali and phenolphthalein, and where the combining weight of the alkaloid is known its amount can be calculated from the result of the same titration. The alkaloids to which the process is not applicable are, so far as at present known, atropine, homatropine, hyoscyamine, hyoscine, and, according to P 1 u g g e {Arch. Pharm., [3], xxv. 45), the volatile alkaloids c o n i n e and nicotine. In the cases of brucine, morphine and thebaine, a red coloration is obtained somewhat before the end of the reaction, but a little experience is stated to surmount this difficulty. M o,r p h i n e acts as an acid to Poirriers soluble blue (CLB), probably owing to the presence of the two hydroxyl groups (M. K. En gel, Compt Bend., cii. 214). Lacmdid has been used by Van Itallie {Analyst, xiv. 118) for the titration of certain alkaloids, including atropine, hyoscy- amine and Conine, the hydrochlorides of which are stated to be neutral to this indicator. Rosolic acid has been employed by E. Dieterich (Pharm. Jour., [3], xvii. 888) for the determination of the alkaloids in extracts of aconite, belladonna, hyoscyamus, conium, and nux vomica, but his results leave the value of the indicator somewhat in doubt. Many of the alkaloids are more or less changed when heated ^ In titrating an alkaloid with methyl-orange, it is rarely convenient to employ an aqueous solution of the base. A solution of the alkaloid in proof or rectified spirit is generally suitable, and the indicator is fairly sensitive under such conditions. But when the alkaloid is much coloured, as is fre- quently the case in the assay of the bases directly extracted from their sources, it becomes difficult or impossible to observe the end of the reaction. Under such circumstances, the writer has overcome the difficulty by dissolving the alkaloid in a little ether, and placing the solution in a small stoppered cylinder, together with a few centimetres of water, coloured with a drop of methyl-orange solution (1:1000). On then gradually dropping in the standard acid and agitating thoroughly after each addition, it is easy to observe the end of the reaction, as the colouring-matter remains in the upper ethereal stratum, and presents a marked contrast to the red colour of the aqueous liquid. By operating in this manner and employing ^ hydrochloric acid, the author has obtained perfectly satisfactory estimations of aconitine, &c., even when working on as little as '030 gramme. 132 SAPONIFICATION OF ALKALOIDS. with dilute acids, in many cases suffering hydrolysis {e.g., atropine, cocaine, aconitine) or being converted into uncrystallisable isomers {e.g., quinine, cinchonine). Concentrated hydrocliloric acid, with application of heat, converts certain of the alkaloids {e.g., morphine, codeine, aconitine) into the so-called apo-bases, with loss of the elements of water. In other instances, one or more methyl-groups are split off (cocaine, colchicine). For colour- reactions, see page 145. Concentrated nitric acid oxidises and decomposes the great majority of the alkaloids, nitro-derivatives being formed in many cases as intermediate products. In many cases, nitric acid yields more or less characteristic colour-reactions with the alkaloids (page 146). Concentrated sulphuric acid decomposes the great majority of the alkaloids, the change being sometimes accompanied by interesting colour-reactions (page 145). On applying heat, charring frequently ensues. Strychnine survives to some extent a treatment with concentrated sulphuric acid at 100°. Reactions of the Alkaloids with Alkalies. The fixed alkalies, lime, baryta, and ammonia, liberate the plant-bases from their salts, and as the free bases have, as a rule, but limited solubility in water, they are commonly pre- cipitated when the reagent is added to their solutions. The base usually appears as a white, very bulky or flocculent pre- cipitate, often exhibiting a crystalline appearance, either at once or on standing. The precipitates are often hydrated, and some- times can only be rendered anhydrous with difficulty. In some cases, the plant-bases when freshly liberated from solutions of their salts by fixed alkalies, alkaline earths, or ammonia, are soluble in excess of the precipitant. Thus morphine and codeine dissolve readily in excess of caustic potash or soda, and slightly in ammonia, and morphine is also soluble in lime and baryta water. Quinine, but not other cinchona alkaloids, dissolves in excess of ammonia, and strychnine also to a limited extent. The carbonates of the alkali-metals react somewhat peculiarly with the salts of the alkaloids. Few of the alkaloids form carbonates, so that the precipitates produced by alkali-metal carbonates usually consist of the free plant-bases. But the salts of some alkaloids are not precipitated at all by potassium or sodium carbonate {e.g., codeine), and others which are thus pre- cipitated are unaffected by bicarbonates (e.^., strychnine, brucine, atropine, veratrine). SAPONIFICATION OF ALKALOIDS. 133 A few of the alkaloids give characteristic colour-reactions when added to fused caustic potash.^ Saponification of Alkaloids. Many of the alkaloids, when boiled with a fixed alkali, baryta, or lime, undergo hydrolysis, with formation of a base of less complex constitution, and the salt of an acid usually belonging to the aromatic series. The change is strictly analogous to the saponification of fats and ethereal salts, and can be ejffected by boiling with dilute acids as well as by alkalies. The following equations represent the more important cases of saponification of alkaloids, and show the products of the reaction in each case: — Aconitine. + Kfi = C2eH,,N0,, Aconine. H- C7H6O2 Benzoic acid. Pseudaconitiue. + HgO Pseudaconine. + Dimethyl-proto- catechuic acid (Veratricacid). Cs7H5sNO,i Veratrine. + Bfi Verine. + Veratric acid. Cevadine. + HgO = C,,H,3N0, Ccvine. + Methyl-crotonic acid. Narcotine. + H2O Hydrocotarnine. + Meconin. C„H,3N03 Atropine. + H2O Tropine. + Tropic acid. Cocaine. + H2O Benzoyl-ecgonine. + CH,0 Methyl-alcohol. C,,H,,NO, Benzoyl-ecgonine. + HgO Ecgonine. + Benzoic acid. Piperine. + H2O Piperidlne. + C12H10O4 Piperlc acid. CaeH^sNO, Sinapine. + 2H2O Choline. + CnHxA Sinapic acid. * According to W. L e n z (Zeitschr. Anal. Chem., xxv. 29), out of 72 alkaloids examined, only the following gave characteristic colours when fused with caustic potash, 0*5 milligramme being used in each case : — Quinine, a grass-green and peculiar odour; quinidine, green, becoming yellower and finally brown; cinchonine, brownish-red to violet with green edges, changing to bluish-green; cinchonidine, green, changing to grey ; cocaine, greenish -yellow, turning to blue and dirty red on stronger heating. 134 PIGRATES OF ALKALOIDS. General Precipitants of Alkaloids, Alkaloids as a class give precipitates with a considerable number of reagents, especially compounds of some of the heavy metals. The three precipitants of most general applicability are, perhaps, a solution of iodine in iodide of potassium, a solution of phosphomolybdic acid (Somnenchein's reagent), and a solution of the double iodide of mercury and potassium (Mayer's reagent); but neither these nor any other known reagent wiU precipitate every alkaloid without exception. With the exception of tannin, which should be applied in a strictly neutral or faintly alkaline solution, the precipitants for alkaloids should usually be added to a solution of the base slightly acidulated with sulphuric or acetic acid, but in some cases (as in the precipitation of certain picrates) the solution should be strongly acidulated with sulphuric acid. Picric Acid, CgH2(N02)3.0H. Hager^s Reagent. When used as a test for alkaloids, picric acid is best employed in saturated, cold, aqueous solution (1 : 100). The alkaloidal solution should be rendered distinctly acid with dilute sulphuric acid, except in cases where the alkaloid to be precipitated or sought for is only thrown down in neutral solutions. The precipitated picrates have usually a pale yellow colour, and are either crystalline or become so after a time, the forms in many cases being characteristic. Picric acid produces no precipitate in solutions (acidulated with sulphuric acid) of aniline, caffeine, conine, morphine, pseudomor- phine, solanine, theobromine, or the glucosides ; and aconitine, atropine, nicotine, and veratrine are precipitated in concen- trated solutions only. Atropine and morphine are precipitated from tolerably concentrated neutral solutions. Copious precipitates are produced by picric acid in acidulated solutions of berberine, colchicine, delphinine, emetine, the cinchona alkaloids, opium alkaloids (except morphine and pseudomorphine), &c. Picric acid is especially suitable for the precipitation of the cinchona alkaloids, and Hager has devised a process of assaying bark based on that fact (see Assay of Cinchona bark). Nicotine, brucine and berberine may also be conveniently estimated by picric acid. They should exist as sulphates in moderately acid solution, and the picric acid be employed as a cold, saturated, aqueous solution, of which 150 c.c. will be necessary to precipitate 1 gramme of the sulphate of a cinchona alkaloid, and twice as much for nicotine sulphate. The following are the limits of dilution at which precipitation occurs, and the characters of the precipitates, according to T. G. W o r m 1 e y : — PICRATES OF ALKALOIDS. 135 Alkaloid. Character op Precipitate. Limit of Precipitation. Nicotine, . . . Conine, .... Morphine, Amorphous, changing to crystal- line tufts ; soluble in nicotine. Amorphous, or liquid globules be- coming crystalline; soluble in conine and acetic acid. Amorphous. 1:40,000 1:500 1:500 Codeine, .... Amorphous. 1:2,000 Narceine, . • Amorphous ; soluble in acetic acid. 1:5,000 Strychnine, . Bnicine, .... Amorphous, quickly assuming characteristic crystalline forms. Amorphous, becoming crystalline. 1:20,000 1:10,000 Aconitine, Amorphous ; insoluble in ammonia. 1:5,000 Atropine, Veratrine, Jervine Amorphous, changing to very char- acteristic crystalline forms ; soluble in weak acid, including acetic. Amorphous ; soluble in weak acids, including" acetic. Amorphous. 1:1,000 1:5,000 1:1,000 Solanine, Qelsemine, . Gelatinous; soluble in excess of picric acid solution. Amorphous. 1:1,000 1:500 The alkaloids may be recovered from their picrates by mixing the moist precipitate with sodium carbonate, drying the mixture, and extracting with alcohol; or the picrate may be shaken with ammonia and a suitable immiscible solvent. Tannic Acid precipitates the great majority of the vegetable alkaloids. The precipitates are usually soluble in very weak acids, and in ammonia. The tannates of aconitine, brucine, caffeine, colchicine, morphine, physostigmine, and veratrine are dissolved by dilute acetic acid and tannate of quinine by somewhat stronger acid. The tannates of aconitine, berberine, (brucine,) caffeine, cinchonine, colchicine, narcotine, papaverine, thebaine, solanine, strychnine, and vera- trine resist more or less perfectly the action of cold dilute hydrochloric acid. The tannates of aconitine, physostigmine, quinine, solanine, and veratrine are not redissolved by cold dilute sulphuric acid. Aconitine, physostigmine, and veratrine are completely precipitated by tannic acid from sohitions strongly acidulated by sulphuric acid, but only partially from slightly acidulated solutions. An alkaloid may be recovered from its tannate by mixing the moist precipitate with recently precipitated lead carbonate or hydroxide, drying the mixture, and boiling it with alcohol i36 sonnenschein's reagent. or other suitable solvent, which, on evaporation, will often leave the alkaloid in a characteristic crystalline form. Phosphomoltbdio Acid. Sonnenschein s Reagent. One of the most valuable general tests for alkaloids, and reagent for separat- ing them from foreign matters, consists of a solution of sodium phosphomolybdate in nitric acid. It is prepared by acidulating a warm solution of ordinary sodium phosphate with nitric acid, and adding an excess of ammonium molybdate solution. The yellow precipitate is separated, washed with water, acidulated with nitric acid, and dissolved in a hot solution of sodium carbonate. The solution is evaporated to dryness and ignited at a low red heat till all ammonium salts are volatilised, the residue moistened with nitric acid, and again ignited. The product, consisting of p h o s- pho-molybdate of sodium, is dissolved in ten times its weight of a mixture of one measure of strong nitric acid (sp. gr. 1*42) with nine measures of water. Sonnenschein's reagent gives yellow, usually amorphous, precipi- tates with nearly all alkaloids, and as most of the precipitates are very insoluble, a negative reaction with the phosphomolybdic solu- tion affords in many cases a positive proof of the absence of alkaloids ; but, on the other hand, ammonium salts and other non- alkaloidal bodies are also precipitated by Sonnenschein's reagent. The phosphomolybdates are decomposed by ammonia, in some cases with production of a white precipitate of the liberated alkaloid, which can usually be dissolved by agitation with a suitable solvent, e.g.^ chloroform, ether, benzene, amylic alcohol; but when the alka- loid is readily oxidisable, treatment of the phosphomolybdate with ammonia is attended with the blue or green coloration indicative of reduced molybdic acid. This occurs in the case of aconitine, aniline, atropine, berberine, codeine, colchicine, conine, morphine, nicotine, physostigmine, &c. Where such reaction occurs the alka- loid is best recovered by mixing the moist phosphomolybdate precipitate into a paste with potassium or sodium carbonate, and extracting with strong alcohol. Phosphotungstic Acid, Scheiblers Reagent^ is used in a similar manner to Sonnenschein's phosphomolybdic solution, and gives very similar reactions with alkaloids. It is prepared by dissolv- ing 100 parts of sodium tungstate and 60 to 80 parts of sodium phosphate in 500 parts of water, and adding nitric acid to acid reaction ; or ordinary sodium tungstate may be digested with half its weight of phosphoric acid of 1*13 specific gravity, and allowed to stand for some days, when phosphotungstic acid will separate in crystals. Scheibler's reagent precipitates 1 : 200,000 solution of Rtrychnine and 1:100,000 solution of quinine. The alkaloids WAGNER'S REAGENT. 137 may be recovered from their phosphotungstates in the same manner as from their phosphomolybdates (see above). Metatungstic Acid, Silicotungstic Acid (E. G o d e f f r o y), and Phosphoantimonic Acid (S c h u 1 1 z e) have been proposed as pre- cipitants of alkaloids, but the advantages claimed for them have not led to their general adoption. Bromine dissolved to saturation in strong hydrohromic acid has been recommended as a general reagent for alkaloids by T. G. W r m 1 e y. It is probable that hydrochloric acid might be sub- stituted for the hydrobromic acid without detriment to its efficacy. Wormley^s Reagent produces yellow amorphous precipitates in solu- tions of many alkaloids, and crystalline precipitates with meconin (moderately strong solutions), atropine, hyoscyamine and veratrine, the microscopic appearance of the precipitate being in each case characteristic.^ Iodine dissolved in a solution of potassium iodide, Wagner's Reagent, yields reddish or red-brown precipitates with nearly all the alkaloids, even in very dilute solutions. The precipitates are formed more readily in solutions acidulated with sulphuric acid, and when applied under these conditions the reagent is in effect iodised hydriodic acid. Excess of the reagent should be avoided. The quantity used should not be sufficient to colour the solution yellow. Precipitation is so general, and occurs in such dilute solutions, that a negative reaction is conclusive proof of the absence of ordinary alkaloids, though precipitation is not conclusive proof of the presence of an alkaloid. The precipitates from aqueous solutions are usually amorphous, though codeine, narceine, and strychnine are exceptions. In alcoholic solutions the precipitates are sometimes not formed, or are deposited very slowly ; but when produced, they are often of different character from those yielded in aqueous solutions, and in some cases are crystalline. The pre- cipitates are mostly poly-iodides of the alkaloids, the formulae in some cases being very complex. Thus with quinine there is first a formation of BHI,I; with more of the reagent, BHI,I^ is obtained ; while in alcoholic solution, in presence of free sulphuric acid, and ^ C. L. B 1 X am {Chem. News, xlvii. 215) has pointed out that certain of the alkaloids give characteristic colour-reactions when bromine-water is added drop by drop to their solutions in dilute hydrochloric acid. Thus, brucine is stated to yield a violet colour, and strychnine the same on boiling ; narcotine a rose pink, and the same with quinine, changed in the latter case to the characteristic grass-green colour on adding ammonia. With excess of bromine, strychnine, brucine and narcotine readily give yellow precipitates ; whilst quinine, morphine and cinchonine are only precipitated with difficulty or from strong solutions. 138 dragendorff's reagent. with an excess of the reagent, the curious iodo-sulphate of quinine or herepathite, ^ ^,3112^0 ^,2TLI,l^-{-^ aq., is pro- duced. Atropine, strychnine, berberine, and piperine are among other alkaloids giving characteristic compounds with Wagner's reagent. The alkaloids may be recovered from their polyiodides by treating the precipitate with sulphurous acid, a sulphite and dilute sulphuric acid, or sodium thiosulphate, and then adding an alkali and shaking with a suitable immiscible solvent. Treatment with sodium thiosulphate (" hyposulphite "), avoiding excess, is a con- venient means of purifying the polyiodides from co-precipitated foreign matter. The reduced solution is filtered and again treated with Wagner's reagent, when the polyiodide is obtained in a con- dition of purity. The strength of Wagner's reagent may vary within wide limits. Ordinary decinormal solution of iodine is of suitable strength, or a solution containing 20 grammes of iodine and 50 of potassium iodide per litre may be used. PoTASSio-IoDiDE OP Cadmium, MarmS's Reagent, employed in solutions acidulated with sulphuric acid, gives with alkaloids pre- cipitates which are at first amorphous, but which subsequently become crystalline. They are soluble in alcohol, and in excess of the cadmium solution. PoTASSio-IoDiDB OP BiSMUTB, Dvageudorff's Reagent, is best made by mixing 16 measures of the B.P. solution of citrate of bismuth with 1 of strong hydrochloric acid (sp. gr. 1*16), and add- ing iodide of potassium equal in weight to the hydrochloric acid used ( J. C. T h r e s h). The resulting liquid has an orange colour, and when added to solutions of alkaloids, strongly acidulated with sulphuric acid, forms orange-red precipitates, which appear to be, in most cases, wholly insoluble in cold water. The following are the limits of delicacy, according to J. C. T h r e s h {Pharm. Journ., [3], X. 641, 809) :— Strychnine, 1 in 250,000; quinine, 1 in 200,000; quinidine, 1 in 160,000; cinchonidine, 1 in 125,000; narcotine, 1 in 50,000; brucine and aconitine, 1 in 40,000; atropine, 1 in 25,000; morphine and narceine, 1 in 20,000; codeine, 1 in 17,500; apomorphine, 1 in 12,500; berberine, 1 in 6000 *,. caffeine, 1 in 3000. (See also F. Mangini, Gazetta^ 1882, 155 ; Journ. Chem. Soc, xlii. 900.) Potassio-Mercurio Iodide, Mayers Reagent, is prepared by dissolving 6*775 grammes of dry crystallised mercuric chloride^ and 25 grammes of pure potassium iodide separately in water, mixing the solutions so obtained, and diluting the mixture to 1 litre. The solution thus obtained is | normal, and of con- venient strength for general use, though of only one- half the MAYER'S SOLUTION. 1S9' strength originally proposed by F. F. M a y e r ^ (Chem. Neios, vii. 159). Mayer's Solution precipitates the great majority of alkaloids, and in some cases from very dilute solutions. Applied, as it always should be, to solutions rendered distinctly acid by hydrochloric or sulphuric acid, ammonia does not interfere ; but the solution to be tested must not be more than slightly alcoholic, and must not con- tain acetic acid. The precipitates yielded by alkaloids with Mayer's solution are usually yellowish-white in colour, and curdy or flocculent. They are more or less soluble in alcohol, ether, acetic acid, iodides, and sometimes in an excess of the reagent. Certain other organic matters besides alkaloids are also precipitated by Mayer's solution, which therefore loses much of its value when applied to unpurified solutions. Mayer's solution is chiefly valuable as a means of making an approximate volumetric determination of the alkaloid present in a solution; but unfortunately the composition of many of the precipitates obtained with it varies to a serious extent with the concentration of the solution, the proportion of the acid present, and the excess of the reagent. With strychnine, the composition of the precipitate produced by Mayer's solution approximates to BHIjHgIg ; with morphine it ap- pears to be a variable mixture of B(HI)4,(Hgl2)3 and B(HI)g,(Hgl2)3; while with quinine the precipitate is not far from the composition B2(HI)3,(Hgl2)3. These formulae refute the statement made by Mayer, and reproduced by various writers, that the precipitates are of definite composition, containing either 1, 2, or 3 molecules of the base. It has been proved by Lyons that the precipitates nearly always contain a smaller proportion of mercury (often less than three-fourths) than has been assumed to be present in them. The subject has also been investigated by A. B. P r e s c o 1 1 {Ghem. News, xlv. 114, 123). If Mayer's reagent be added till precipitation ceases, there will always be a large excess of the reagent present. This excess bears a relation to the dilution of the liquid, and the more dilute the solution, the larger the volume of Mayer's solution requisite to * A. B. Prescott has pointed out {(Jliem. News, xlv. 114, 123) that the proportions of mercuric and potassium iodide used in making Mayer's- solution correspond to Hglg + eKI, which might be supposed to react to form 2KI,Hgl2 + 2KI + 2KCl ; but the reactions of the solution point rather to the formula KI,Hgl2 + 3KI + 2KCl. Nevertheless, the proportion of potassium iodide cannot be greatly reduced without precipitation of mercuric iodide ; but a permanent solution can be obtained with mercuric chloride, potassium iodide, and potassium bromide, used in the proportion indicated by the formula. HgCl2+4KI + KBr. 140 TITRATION BY MAYER's SOLUTION. effect complete precipitation. Hence, in order to render titration with Mayer's solution of any value, it is essential that the solutions operated on shall be nearly of uniform strength, and that the re- agent be added in exactly the same manner. It is further desir- able, whenever possible, to make an experiment, side by side with the alkaloidal solution, with a known weight of the same alkaloid in a state of purity, so as to avoid all assumption as to the be- haviour of the volumetric solution with the alkaloid in question. The following is the usual method of performing the titration of an alkaloid with Mayer's solution : — The solution, which should be distinctly acidulated, and contain, as a rule, 0'5 per cent, of the alkaloid, is treated with Mayer's solution as long as a dis- tinct precipitate is produced. As there is no definite end-reaction, and no satisfactory indicator has been as yet devised,-^ it is necessary to filter a portion of the solution to ascertain if the precipitation is complete. A minute filter, about half an inch in diameter, sup- ported on a ring of platinum-wire, may be used. A drop or two of the filtered liquid ^ is placed on black glass, or on ordinary glass on black paper, and a drop of the volumetric solution added from the burette, when the faintest turbidity will be readily perceived. Before the end of the titration, all the trial-filters and test-drops are re- turned to the solution containing the main quantity of the precipitate. The end of the reaction is the point at which the Mayer's solution ceases to produce a precipitate, and it is worthy of notice that, before this point is reached, a condition of equilibrium is attained, in which the solution is liable to be precipitated by the addition of either alkaloidal solution or the mercury reagent. A, B. Lyons has investigated the behaviour of various alka- loids with Mayer's solution, noting the effect of concentration and the volume of the reagent required to precipitate completely a definite weight of alkaloid; in addition, the volume required to produce an apparent excess of the mercury reagent (so that the liquid would give a precipitate with more of the alkaloidal solu- tion) ; and also the actual excess of Mayer's solution used, as esti- mated from the quantity of mercury present in the solution. Lyon's results are given in the following table, reproduced from his Manual of Pharmaceutical Assaying. The mercurial solution was ^ normal, and 0*1 gramme of alkaloid was employed in each case : — ^ F. F. Mayer proposed to ascertain the excess of the reagent by titrating back with standard nitrate of silver solution, without filtering, using potas- sium chromate as an indicator. As pointed out by Lupin ski, the sug- gestion ignores the accumulation of chlorides and iodides in the solution, as also the fact that some of the precipitates react but slowly with nitrate of silver. 2 A convenient form of filter-tube for the purpose has been described by F. C. J. Bird {Pharm. Jour., [3], xvii. 826). PRECIPITATION BY MAYERS SOLUTION. 141 Alkaloid. Solution. Volume of Reagent in c. c. Weight of Alkaloid precipitated Weight of Fresh Precipitate after drying at 100° C. For For com- Used by 1 c.c. of Condition. Strength. apparent plete pre- in Reagent. excess. cipitation. excess. Acoiiitine, 1:200 7-1 2-0 •0141 •180-^190 Atropine, 200 7-b 131 8-0 •0077 •216- ^220 ... 400 6-0 14-0 3-5 •0072 ... 600 6-0 15-0 3-6 •0067 •192--200 Berberine, 200 3-8 •0263 ... 400 3-9 •0257 ... 600 ... 4-6 .. •0218 •200- ^215 Brucine, NeariV 200 .'.'. 8-0 i'7 •0125 ... neutral. » Nearly neutral. 1:400 ... 8-8 ... •0114 ... » Acid. 1:400 ... 9-8 ... •0102 ... If Nearly 1:600 ... 9-2 •0109 neutraL Cinchonidine, 100 12-4 13-8 1-0 •0073 , ... 200 12-4 13-6 0-7 •0074 •330^*375 \\ '.'!. 200 16-6 2-6 •0064 Cincho'nine, 100 12-8 0-8 •0078 '.'.'. 100 ... 14-0 1-2 •0072 ... NeutraL 200 7-9 10-8 •0093 •333- -345 Acid. 200 8-0 14-2 ... •0071 ... M • • NeutraL 400 8-0 12-4 2*4 •0082 ... Acid. 400 9-6 14-18 ... •007 to •OOSO ... Cocaine, 200 12-8 ... •0078 •246 ... 400 100 14-4 4-6 •0069 ... '.'.'. 600 16-0 5-2 •0063 ... Colchicine, . '.'.'. 200 s'-2 9-2 •0109 •160 »» ... 400 4-2 11-4 ... •0088 ... ... 600 5-0 12-6 •0080 ... Emetine, ... 800 4-0 14-6 ... •0067 ... ... 200 8-0 9-4 o-i •0106 •256 ... 400 8-8 iO-2 10 •0098 ... ... 600 10-6 0-6 •0094 Gelsemine, . '.". 200 5"8 10-4 •0096 •185--200 . ... 400 6-5 12-0 ... •0084 Hydrastine, . ... 200 7-4 ... •0135 •200^'-210 ... 400 ... 8-0 ... •0125 ... ... 600 ... 8-4 ... •0119 Hyoscyamine, ... 200 8-5 •0116 •226-^250 Morphine, . ... 200 t'o 4-91 ... •0128 •190- -240 400 8-9 0-6 •0110 Pilocarpine, . ... 200 4-8 16-8 ... •0060 •240^-350 i> • • ... 200 20-0 ... •0050 ... Quinine, Neutral. 200 li'-e 16-4 ... •0061 ... , Acid. :200 12-4 18-0 ... •0056 •310- ^335 >» • 400 12-8 16-8 ..'. •0060 ... ... :600 12-2 20-0 •0050 ... Strychnine, . ... .200 11-0 6*6 •0091 •260-^275 j> Neutral. :400 11-6 12-0 ... •0084 ... i> • • Acid. :400 11-6 12-2 ... •0082 ... >i ... :600 11-2 11-9 0-6 •0087 ... From a study of this table by Lyons, it appears that while a notable excess of the reagent is generally needed to effect com- plete precipitation, the weight of the precipitate is in many cases considerably below the amount indicated by theory. Better results in this respect are obtainable by allowing the liquid with the sus- pended precipitate to stand for some time. Lyons states that, under these circumstances, the atropine precipitate becomes dense 142 PKECIPITATION BY MAYER'S SOLUTION. and crystalline, and in part adheres to the beaker, in which it can be washed by decantation, dried, and weighed, the amount thus found falling little short of the theoretical weight of 0'245 gramme for 0*100 of alkaloid. The following data showing the behaviour of alkaloids with Mayer's solution are tabulated from the descriptions of D r a g e n- d r f f {Plant-Analysis and Analyse Chimique de quelques Drogues Actives) : — Milli- Correction Alkaloid. Dilution of Solu- tion. grams of Alka- loid Ppted. by 1 C.C. for Solu- bility. Mgrms. for 10 C.C. Filtrate. Observers. Conditions of Precipitation. Aconitine, . 13-45 0-5 DragendorflE. Pseudaconitine, . ... 19-4 ... Atropine, 1:200 4-85 ... „ \ Ample time required / for precipitation. >> 1:380 4-14 0-5 ' Hyoscyamine, 1:200 3-49 ... Emitine, 9-45 ... Conine, 1 :"200 6-25 ... ,, \ Faintly acid only. / KCl present. „ ... 2-10 Mayer. Nicotine, . ... 2-02 ... Dragendorff. rSol. strongly acidu- i lated. Strychnine, . ... 8-35 ... >» Brucine, ... 8-30 9-85 ... Mayer. Dragendorff. [• Sol. faintly acid only. Colchicine, . '. 1 :m 11-65 15-85 ... Kndorff.f SOL strongly acid. Morphine, . ... 10-00 ... jj ... Narcotine, . ... 10-65 ... Veratrine, . 14-80 0-7 Masing. 1 ... 13-50 Mayer. (slightly acid solu- Sabadilline, . ... 18-70 0-5 Masing. f tion. Sabatrine, . 16-63 0-4 '' J Physostlgmine, . ... 6-87 1-0 Berberine, . ... 21-25 ... Beach. ... Chelidonine, ... 8-37 ... Masing, ... Sanguinarine, 7-42 ,, ... Quinine, 5-40 ... ... ... Cinchonine, . 5-10 ... Hereth (Pharm. Record, 1886, page 209) has proposed an improved method of operating with Mayer's solution, which allows time for the precipitate to fully form. A number of equal portions of the solution to be tested are treated with volumes of the mercurial solution, regularly increasing by 0*1 c.c, and allowed to stand eight or ten hours. Trial-portions of each mixture are then removed and tested with two drops of Mayer's solution, when a particular mixture will be found to have the mercurial solution in slight excess, while in the previous mixture it is deficient. Obviously, the true amount lies between the two, and it is easy to ascertain the exact volume required. Strychnine and quinine are among the alkaloids yielding the most insoluble precipitates with Mayer's solution. With atropine CHLOROPLATINATES OF ALKALOIDS. 143 :and morphine the reaction is far less delicate, and caffeine and theobromine are not precipitated at all. Mercuric Chloride, HgClg, gives, with certain alkaloids, precipi- tates of which the crystalline form or melting-point is character- istic. As a rule, the precipitates have the constitution BgHgHgCl^, and are less insoluble than those produced by Mayer's reagent. Auric Chloride, AuClg, gives yellow precipitates of alkaloidal aurochlorides or chloraurates with hydrochloric acid solutions of many of the alkaloids. The double salts precipitated are often very insoluble. They usually contain BjHCljAuClg or BHAuCl^, though this formula is not without exception. Auric chloride has the advantage that ammonium salts and the simpler amides are not precipitated by it ; but the precipitates are unstable, the yellow colour in many cases rapidly changing to reddish brown, while the supernatant liquid occasionally acquires an intense red colour. Platinic Chloride, PtCl^, is a useful reagent for many alkaloids, with the hydrochlorides of which it combines to form chloro- platinates or platinochlorides. In some instances, these double salts have the formula BHgPtClg, and in other cases they contain BgHgPtClg, while in a few instances more complex formulae have been attributed to them. It is sometimes stated that the alkaloids containing Ng in the molecule form chloro- platinates of the first formula, while in the case of bases having only one atom of nitrogen the platinum salts contain two atoms of alkaloid ; in other words, that the ratio of N : Pt is con- stantly as 2:1. This, however, is far from being the case, for alstonine, gelsamine, aspidospermine, paytine, strychnine, pilo- €arpine, and numerous other bases containing Ng agree with the opium bases, berberine, cevadine, atropine, and others containing ]S" in forming platinum salts of the formula B2H2PtClg. In addition, many of the cinchona-bases form platinum salts of both series. The chloroplatinates of the alkaloids vary in colour from pale yellow, through orange and red, to brownish red. They are mostly sparingly soluble in water, and hence are usually formed as precipitates on adding platinic chloride to a solution of the alkaloid acidulated with hydrochloric acid. The similar behaviour of potash and ammonia diminishes the value of the test. Xanthine, caffeine, colchicine and pelletierine are among the alkaloids not precipitated. Of the rest, the chloroplatinates of quinine, cin- chonine, morphine and strychnine are among those dissolved by hydrochloric acid. The melting-points of the alkaloidal chloroplatinates are often characteristic. Potassium Permanganate, KMnO^, produces characteristic 144 COLOUR-REACTIONS OF ALKALOIDS. reactions with certain of the alkaloids. Beckurts and List have examined the behaviour of a number of them, by add- ing a decinormal solution of the reagent, drop by drop, to a cold saturated aqueous solution of the hydrochloride of the base. Immediate reduction of the permanganate, with separation of brown manganese oxide, was observed with the hydrochlorides of quinine, cinchonidine, cinchonine, cinchonamine, brucine, veratrine, colchicine, conine, nicotine, aconitine, physostigmine, codeine, and thebaine. The solutions of atropine, hyoscy amine, pilocarpine, berberine, piperine, and strychnine were coloured red, the reagent being only gradually reduced. With morphine hydrochloride the permanganate produced a white crystalline precipitate of oxydimorphine, which, when filtered off and dried, could be recognised by its characteristic reactions. Apomorphine hydrochloride immediately reduced the reagent, with production of an intense green colour. On adding a few drops of a decinormal solution of potassium permanganate to a concentrated solution of narceine hydrochloride a reddish precipitate is immediately formed, which is very stable in the cold and in the absence of an excess of the reagent, but is decomposed on heating or by addition of more permanganate. Solutions of papaverine hydrochloride, and of narcotine if diluted with hydrochloric acid, at first behave similarly ; but the precipi- tates are much less stable than narceine permanganate, and soon discolour and decompose with separation of brown manganese oxide. F. Geisel (Pharm. Zeit, 1886, p. 132) has pointed out that cocaine gives a comparatively stable permanganate, which forms a purple-violet precipitate of characteristic microscopic appearance. The precipitate forms only slowly in dilute solutions, and under- goes gradual decomposition. Colour-Reactions of Alkaloids. Many of the alkaloids give brilliant, and in some cases characteristic, colorations when treated with appropriate reagents. When possible, the reaction should be compared with that yielded by the pure alkaloid treated side by side with the sample. The reagents which have been proposed as colour-tests for alkaloids are very numerous, and have not always been chosen or applied with discretion, nor with a due regard to purity. The colour-reactions may be classified as: — (1) Those produced by dehydrating agents, such as strong sulphuric acid, phosphoric acid, and zinc chloride;^ (2) those given by oxidising agents ^ In using zinc chloride, Czumpelitz directs that the substance to be examined should be first carefully dried, moistened with a solution of 1 gramme COLOUR-TESTS FOR ALKALOIDS. 145 not of themselves yielding colours, such as nitric acid, chlorine, bromine, and bleaching powder ; or sulphuric acid and oxidising agents, such as potassium chlorate, perchlorate, and perman- ganate ; (3) those given by oxidising agents which themselves yield a coloured product by reduction, such as iodic acid and reagents containing chromic, molybdic, tungstic, and vanadic acids ; (4) and colorations produced by certain special reagents, such as ferric chloride, hydrochloric acid, sulphuric acid and sugar,i &c. As a rule, the best method of observing the colour-reaction of an alkaloid is to apply a drop of the reagent by means of a pipette or glass rod to a minute fragment of the solid alkaloid placed on a porcelain plate or in a flat porcelain dish. An alkaloidal residue obtained by the evaporation in a porcelain capsule of an alcoholic, ethereal, chloroformic or other solution may be very conveniently employed for observing colour-reactions. Fused Caustic Potash gives a few interesting colour-reactions with alkaloids (see foot-note, page 133). Concentrated Hydrochloric Acid gives colour-reactions with a few alkaloids. Thus, reddish colours are yielded with physo- stigmine, sabadilline, sabatrine, veratrine, and veratroidine ; and a yellow with thebaine. On addition of chlorine-water after hydrochloric acid, berberine gives a red colour. Xicotine yields an amorphous hydrochloride and conine a crystalline salt, on evapo- rating the solution in hydrochloric acid. Concentrated Sulphuric Acid gives colour-reactions with a number of alkaloids, the coloration varying with the degree of heat applied. The following reactions have been observed when the acid is dropped on to the solid alkaloid, without applying heat : — No colour^ or a faint straw tint only, is yielded by pure aconitine, atropine, caffeine, chelonidine, cinchonidine, cocaine, codeine, hyoscine, hyoscyamine, gelsemine, morphine (purple to brown on warming), nicotine, pilocarpine, quinine, quinidine, staphisagrine, strychnine, and theobromine. Yellowish colorations are given by colchicine, gnoscopine, jervine, and by many other alkaloids in presence of impurities. Reddish colours are pro- duced either immediately or gradually, with impure aconitine, melted zinc chloride in 30 c.c, of water, and dried again. If thus treated, strychnine takes a scarlet colour, thebaine a y(41ow, narceine an olive-green, delphinine a red-brown, berberine a yellow, veratrine a red, quinine a pale yellow, digitaliu a maroon, salicin a violet-red, santonin a violet-blue, and cubebin a purple. The presence of brucine prevents the coloration of strych- nine, the tinge produced being a dirty yellow {Giornale Farm. Chim. ; Jour, Chem. Soc, xlii. 340). 1 Information respecting this test will be found under "morphine." VOL. III. PART II. K 146 COLOUR-TESTS FOR ALKALOIDS. apomorphine, briicine (pale rose), cocaine (impure), conine (pale red), gelsemine (impure), meconidine, narceine (changing to black), narcotine (yellowish-red, changing to violet and blue), physostig- mine, rhceadine, sabadilline, sabatrine, solanine, taxine, thebaine, veratrine, and veratroidine. Bluish colorations are yielded by cryptopine, curarine (after a time), and papaverine. Greenish colours are given by beberine, berberine, emetine (brownish to green), piperine, pseudomorphine, and sometimes by rhceadine. Some characteristic changes of colour can be obtained by gradually warming the capsule in which the test is being made, by placing it over a small beaker of boiling water. The ultimate result is usually browning and charring of the alkaloid, but the intermediate reactions are often of value. Many substances besides alkaloids give more or less brilliant colour-reactions with strong sulphuric acid. Thus red colorations (often of a brilliant hue) are obtained with amygdalin, columbin, cubebin, elaterin, hesperidin, phloridzin, populin, salicin, sarsaparillin, senagin, smilacin, syringin, and many varieties of tannin. In applying sulphuric acid as a colour-test for alkaloids, it must be remembered that the presence of a very minute quantity of nitric acid, often present as an ' impurity, greatly modifies the colorations produced by many of the alkaloids. Thus, if the treatment with sulphuric acid (without applying heat) be followed by the addition of a very minute quantity of nitric acid (at the and of a glass rod drawn out to a point), or a minute fragment of solid potassium nitrate, the following reactions will be ob- tained : ^ No colour with atropine, caffeine, cinchonidine, cin- chonine, nicotine, pilocarpine, quinidine, quinine, staphisagrine, strychnine, or theobromine ; red coloration with brucine, curarine, narcotine (reddish violet or blood-red), physostigmine, sabadilline, thebaine, and veratrine (gradual change to cherry-red). Special and peculiar changes of colour are produced by morphine, codeine, and colchicine, and are described in the respective sections on these alkaloids. Strong Nitric Acid, of 1*40 to 1'42 specific gravity, gives more or less characteristic colour-reactions with a number of alka- loids. ^ drop of the acid should be applied by means of a glass ^Erdmann applies this test by mixing 6 drops of nitric acid of 1 "25 specific gravity with 100 c.c. of water, and adding 10 drops of the dilute acid so obtained to 20 grammes of sulphuric acid. From 8 to 10 drops of the solution so prepared, or Erdmann's Reagent, is added to 1 or 2 milli- grammes of the solid to be tested, and the colour observed after 20 to 30 minutes. frohde's reagent. 147 rod to a minute fragment of the alkaloid, or to a residue left on evaporating a solution on white porcelain. No coloration is yielded by aconitine (when pure), atropine, caffeine, cinchonidine, cincho- nine, conine, gelsemine (impure, greenish), quinidine, quinine, strychnine, or theobromine. YelloicisU colours are obtained with impure aconitine (colour varies from yellow to red and brown), codeine (orange-yellow), morphine (yellow to red), narceine, narco- tine, papaverine (orange), piperine (orange), rhoeadine, sabadilline (yellow), thebaine, and veratrine. Red shades are produced by impure aconitine (colour varies from yellow to red and brown), apomorphine, beberine (red to red-brown), berberine (red-brown), brucine (blood-red), papaverine (orange-red), pseudomorphine (orange-red), and physostigmine (gradually). Gelsemine yields a deep bluish green residue on evaporation. Blue colours are said to be given by colchicine and solanine ; and by the glucosides igustrin and syringin. SuLPHOMOLYBDic AciD, Fvohdes Reagent, affords one of the most useful of the oxidation-tests for alkaloids ; but it must be borne in mind that the colours produced are in great measure those of the lower oxides of molybdenum, and that various other bodies besides alkaloids readily reduce molybdic acid with forma- tion of these coloured oxides. The reagent itself, if strongly heated, acquires a blue coloration from reduction of the molybdic acid. Frohde's reagent is prepared by dissolving 6 milligrammes of molybdic acid or molybdate of ammonium in each 1 c.c. of strong sulphuric acid. No colour is produced with atropine, caffeine, cinchonidine, cinchonine, conine, delphinine, hyoscine, hyoscyamine, nicotine, strychnine, or theobromine. Yellowish colorations are given by aconitine, colchicine, and piperine. Reddish shades of colour are produced by brucine, emetine (red, changing to green), narceine (red, changing to blue), sabadilline (reddish violet), solanine, thebaine (orange), and veratrine (gradual production of a cherry-red colour). Bluish colours are given by codeine (gradual production of deep blue), morphine (violet-blue, then dirty green, changing to deep blue), narceine (yellowish brown, changing to red and blue), staphisagrine, (violet-brown). Greenish colorations are produced by apomorphine (green to violet), beberine (brown-green), ber- berine (brown-green), emetine (red, changing to green, and turned blue by hydrochloric acid), quinine (pale green), and quinidine (pale green). Of non-alkaloidal bodies, colocynthin gives slowly a cherry-red colour ; elaterin, a yellow ; phloridzin, gradually, blue ; populin, violet ; salicin, violet to cherry-red ; and syringin, a blood-red to violet-red coloration. 148 COLOUR-TESTS FOR ALKALOIDS. SuLPHOVANADio AciD has been recommended byF. Kundrdt {Chem. Zeit., xiii. 265 ; Jour. Soc. Chem. Ind., viii. 421) as a colour-test for alkaloids. The reagent is prepared by dissolving 0"1 gramme of ammonium vanadate in 10 c.c. of strong sulphuric acid. It is stated to give the following reactions, many of which are due to the production of the coloured lower oxides of vanadium, and hence are likely to vary with the proportions of the reagent and alkaloid employed. No coloration is produced by cafifeine or nicotine. Brown by aconitine (light coflfee-brown), codeine (greenish brown, becoming darker), morphine, narceine (changing to dirty bluish violet, then gradually reddish brown), piperine (intense red- dish brown to black), kairine (dirty pink, quickly changing to dirty light brown and brownish green), solanine (cotfee-brown, changing at the edge to purple and in the centre to dirty green, and very gradually becoming an intense violet jelly). Bed colorations are given by atropine (changing to yellowish red and yellow), brucine {intense blood-red, gradually fading), narcotine (blood-red or purple), and veratrine (brownish red, changing to reddish violet). Yellowish or orange colours are produced by cinchonine (changing to green), cocaine (orange, froths on dissolving), physostigmine (greenish yellow, then purple, finally yellow-brown), and quinine (changing to bluish green and greenish brown). Green colorations are produced by colchicine (changing to greenish brown and cofiFee- brown), conine (intense green, changing to brown), and quinidine (faint bluish green). Blue reactions are produced by antipyrine (greenish blue, gradually becoming bluer), and apomorphine (dark violet blue, rapidly changing through dirty green to reddish and light brown). Violet colorations are given by papaverine (gradually changing to bluish green and orange-green), and strychnine (bluish violet, changing to reddish violet, purple, and brilliant red). Of colorations with non-basic principles the following have been recorded: — Antifebrin, purple, rapidly changing to brown; digi- talin, intense brown, with reddish shade; and salicylic acid, brownish green. Picrotoxin and santonin give no coloration with sulphovanadic acid. Ferric Chloride gives a few characteristic colorations, the most important being the blue reaction with morphine and the blood-red with antipyrine (page 35). A freshly-made mixture of ferric chloride and potassium fei'ricyanide (free from ferrocyanide), both in aqueous solution, has a yellowish brown colour ; but in presence of certain alkaloids it is immediately coloured blue (or green) owing to the production of Prussian blue. This reaction was at first regarded as characteristic of the ptomaines or cadaveric bases, but it is produced by any readily oxidisable PHYSIOLOGICAL TESTS FOR ALKALOIDS. l49 alkaloid, and hence is given immediately by morphine, aconitine, physostigmine, &c., and after a short time by hyoscyamine, emetine, colchicine, nicotine, and many of the tar- bases. Oxidation -COLOUR -REACTIONS are also produced by reagents having a more powerful oxidising action than the foregoing. Thus strong sulphuric acid may be employed in conjunction with potassium nitrate, chlorate, perchlorate, permanganate, bichromate, and ferricyanide ; or with metallic peroxides, such as those of man- ganese (Mn02), lead (PbOg), ruthenium (RuOg), uranium (UgOg), and cerium (CegOJ. The most important of the colour-reactions obtained with such reagents are those yielded by strychnine, cura- rine, gelsemine and aniline, which are fully described elsewhere. Physiological Tests for Alkaloids. A large number of the natural alkaloids, if not an actual majority, have well-marked poisonous characters. The symptoms produced are of the varied description, ranging from the nar- cotism of morphine to the paralysis of conine and the tetanus of strychnine. In making experiments on animals it is often advantageous to administer the poison by hypodermic injection of a solution of alkaloid in water, or weak spirit acidulated with acetic acid. Such a plan obviates the loss of the poison by vomiting, which some- times eliminates the greater part of the poison from the system. On the other hand, the subcutaneous injection of small animals is open to certain obvious objections, and in many cases internal administration may be advantageously substituted for it, especially if the animal employed be a rabbit or guinea-pig, and hence not liable to vomit. In many instances, such animals are hopelessly large, and mice, small birds, or frogs must be employed. W y n t e r B 1 y t h has used blowflies with success in some cases, and occasion- ally fish are of service. When the poison is to be given internally, the extract or very strong solution should be made up into one or more small pills with oatmeal, which the animal is either induced to eat or forced to swallow. In the case of linnets and other small birds, a drop of the liquid to be tested should be introduced into the open beak by means of a pipette or feather. In some cases, physiological tests may be advantageously made on human subjects. Besides observing the bitter taste possessed by most alkaloids, the tingling sensation produced on the tongue by aconitine and cocaine can be thus detected. A marked physiological characteristic of many of the alkaloids, sufficiently striking in some cases to serve as actual evidence of their presence, is their effect on the pupil of the eye. The test is 150 EFFECT OF ALKALOIDS ON THE PUPIL. generally made by placing a drop of the alkaloidal solution to be examined, as nearly neutral as possible, on the eye of a rabbit, dog or cat, when, in a time varying from a few minutes to about half an hour, a marked contraction or dilation of the pupil will be observed. A. The pupil is dilated by : — 1. Atropine and belladonna ; hyoscyamine and h y o- seine, and preparations of henbane and stamonium ; s 1 a n i n e ; and extracts from solanaceous plants generally. 2. Cocaine, and preparations of coca. 3. Conine, and preparations of hemlock and other umbel- liferous plants. 4. C y t i s i n e, and preparations of laburnum. 5. Digital! n, and preparations of foxglove. 6. Gelsemine, and preparations of gelsemium (yellow jesamine). 7. Sparteine, and preparations of broom. 8. Yeratrine, jervine, and preparations of hellebore. 9. Hydrocyanic acid and cyanides. Mydriasis, or dilation of the pupil, is so striking a characteristic of atropine and the isomeric and associated bases that these are often grouped together as the "mydriatic alkaloid s." The mydriasis is only observed in the eye to which the alkaloid is applied. B. The pupil is contracted by : — 1. Morphine, and other opium alkaloids and preparations of opium. 2. Aconitine, and preparations of aconite and other mem- bers of the RanunculacecB. 3. Physostigmine, and preparations of the Calabar bean. 4. Strychnine, brucine, and preparations of nux vomica. A similar effect on the pupil is produced by the poisons when taken internally or hypodermically in sufficient quantities. Some- times, as in the case of morphine and preparations of opium, the pupils are contracted during the early stages of the poisoning, but dilated subsequently, especially after death. Nicotine and preparations of tobacco in some cases cause contraction, and in others dilation, of the pupil. In poisoning with aconitine alter- nate contraction and dilation of the pupil is sometimes observed. EXTRACTION OF ALKALOIDS. 151 ISOLATION AND PURIFICATION OF ALKA LOIDS. The vegetable alkaloids are found in all parts of plants, and in many cases constitute their characteristic active principles. It must not be assumed that the active principle is necessarily of an alkaloidal character, though plants and plant-products, which act primarily on the nervous system, producing tetanus, paralysis, or narcosis (e.^., nux vomica, aconite, opium), owe their activity, as a rule, to the presence of an alkaloid. On the other hand, in plants which act primarily on the muscular system (e.g., digitalis), the active principle is usually of a non-alkaloidal character. Where the action of the plant is emetic, cathartic, or purely astringent, the active principle is usually of a neutral or resinous character; but this statement has some marked exceptions, for ipecacuanha, a typical emetic, owes its activity to the alkaloid emetine. An alkaloid never exists in a plant in a free state. It is most frequently present as a salt, often an acid salt, of some organic acid, especially malic acid or one of the varieties of tannic acid. In some instances the acid with which the alkaloid is united is peculiar to the plant in question, as, for instance, meconic acid in opium, quinic acid in cinchona bark, and igasuric acid in nux vomica. In other cases the alkaloid is combined with an inorganic acid, as is the case, in part at least, with the morphine in opium. The natural forms of combina- tion of the alkaloids are almost invariably readily soluble both in water and in alcohol, but insoluble in ether. The general action of solvents on the leading constituents of plants will be seen from the following table, which will also serve to indicate the nature of the bodies likely to be co-extracted with the alkaloid when the respective solvents are employed : — Water. Alcohol. 1 Ether. Alkaloidal salts, . . Soluble. Soluble. Insoluble. Other salts of inorganic acids, Other salts and organic acids. Free organic acids, Mostly soluble. Mostly insoluble. Insoluble. Soluble. Soluble. Mostly insoluble. Soluble. Soluble. Mostly insoluble. Tannins and colouring matters, Sngars, .... Soluble, Soluble. Variable. Soluble. Soluble. Insoluble. Gums and pectous bodies, Soluble. Mostly insoluble. Insoluble. Albuminoids, &c., Soluble. Insoluble. Insoluble. Starch, . . Soluble in hot water. Insoluble. Insoluble. Cellulose, Insoluble. Insoluble. Insoluble. Resins, . InsoluV)le. Soluble. Variable. Fixed oils, . Insoluble. Sparingly soluble. Soluble. Essential oils, Insoluble. Soluble. Soluble. Chlorophyll, . Insoluble. Soluble. Soluble. 162 EXTRACTION OF ALKALOIDS. Alcohol is the solvent best adapted for the extraction of alkaloids from plants, which should, of course, be reduced to a suitable condition. The treatment may with advantage be re- peated several times, the residue being well pressed between each exhaustion, which is preferably effected by a percolator, or some equivalent arrangement. In the final extraction, the addition of a little sulphuric or tartaric acid is often an advantage, but the amount of acid used should be very limited, and its employment is vetoed in the case of readily changeable alkaloids. Hot water may be substituted for alcohol in some cases. When alcohol has been used for the extraction, it should be removed partially or wholly by gentle evaporation before proceeding to the next stage of the treatment. The method to be adopted for the isolation of the alkaloid from the infusion or tincture obtained depends much on its nature, and the object of the experiment. Extraction by immiscible solvents permits the detection of small quantities of alkaloids, which defy methods based on precipitation, and hence this principle is very valuable in toxicological investigations ; but, on the other hand, the alkaloids so extracted are usually less pure than when isolated by other means. Where it is intended to attempt the separation of the alkaloid by conversion into an insoluble or nearly insoluble compound, a variety of precipitants are available, each one of which has special advantages in particular cases. But before resorting to these general precipitants, it is desirable, and in many cases absolutely necessary, to remove from the liquid as much as possible of the inert organic matters. The best reagent for this purpose is lead acetate, which should be added gradually to the previously neutralised liquid, as long as a precipitate continues to be produced, avoiding the use of any considerable excess of the reagent. The precipitate having been filtered off, the filtrate should be treated with basic acetate of lead, which in many cases will produce a further precipitate, to be removed by the filter as before. On adding ammonia to the filtrate, a third precipitate will frequently be produced, but it must be remembered that cinchonine and other sparingly soluble alkalies are liable to be thrown down at this stage.^ (On this account it is undesirable to add basic acetate of lead and ammonia at once, and filter off the joint precipitate.) ^ The threefold treatment with neutral lead acetate, basic lead acetate, and ammonia in presence of lead acetate causes the precipitation of tannins ; most vegetable acids {e.g., malic, tartaric, oxalic) ; albuminoids, starches, and gums ; many glucosides, sugars, and dextrin ; and the majority of colouring matters. ISOLATION OF ALKALOIDS. 153 The liquid, whicia should smell distinctly of ammonia, is next evaporated at a gentle heat till the odour of ammonia has dis- appeared, when the excess of lead is precipitated by a stream of sulphuretted hydrogen or the addition of a moderate excess of dilute sulphuric acid. Of these plans, the first is much to be preferred. The lead sulphide often carries down with it a notable quantity of colouring matter, otherwise difficult to remove, and the excess of sulphuretted hydrogen is easily got rid of by concen- trating the filtrate at a gentle heat. When sulphuric acid has been employed to precipitate the lead, the filtrate should be carefully neutralised before attempting to further concentrate the liquid, otherwise the alkaloid may suffer partial or complete decom- position. The alkaloidal solution, having been purified by the foregoing treatment, may be treated v/ith one of the general reagents for alkaloids, the choice of which will necessarily depend on the nature of the base supposed to be present. Where this is unknown, preliminary tests with various precipitants should be made on small aliquot fractions of the solution. Although other reagents may be preferable in particular cases, the choice will generally lie between one of the following precipitants : — 1. A fixed alkali, carbonate of alkali-metal, lime, or ammonia; suitable for precipitating morphine, the cinchona alka- loids, the aconite bases, &c. 2. Picric acid (page 134); very suitable for precipitating the cinchona bases, emetine, berberine, and veratrine. 3. Tannic acid (page 135). 4. Phospliotungstic or phospliomolyhdic acid (page 136); available for the great majority of alkaloids, and especially for strychnine. 5. Iodised iodide of potassium (page 137), which produces very insoluble precipitates with the great majority of alkaloids. 6. Mayer's solution (potassio-iodide of mercury) (page 139); valuable for precipitating emetine and the opium bases. With the exception of tannic acid, which should be applied to the neutral or even faintly alkaline solution of the alkaloid, the reagent should be added to the acidulated solution, sulphuric acid being the most suitable acid to bring the liquid to the proper condition. In most cases precipitation is tolerably rapid, but it is desirable, as a precaution, to wait 24 hours before proceeding with the filtration. This is especially necessary perhaps in the case of precipitants 1 and 2. The alkaloid may be 154 USE OF IMMISCIBLE SOLVENIS. recovered from the precipitate in the manner described on page 135 e^ seq. As a rule, the salts of the alkaloids are not soluble in immiscible solvents, and hence when the acidulated solution of an alkaloid is agitated with chloroform, ether, petroleum spirit, benzene, or amylic alcohol, tlie solvent does not remove the base from the aqueous liquid. This behaviour broadly distinguishes alkaloids from glucosides; but, owing chiefly to their weak basic character and the instability of their salts, caffeine, colchicine, delphinine, narcotine, papaverine, thebaine, and theobromine are partially or wholly removed from their acidulated solutions on agitation with chloroform, while amylic alcohol is stated to extract berberine and veratrine in addition to the above bases. Extraction by Immiscible Solvents. The behaviour of the alkaloids, when their acid and alkaline solutions are agitated with immiscible solvents, is of the highest practical value for their isolation and identification.-^ The immiscible solvents used for the extraction of alkaloids, &c., should be free from any trace of fixed or difficultly volatile organic matter. This is best ensured by shaking the solvent with water slightly acidulated with sulphuric acid, separating the aqueous liquid, and redistilling the immiscible solvent at a moderate tem- perature — rejecting the last portion. The distillate should then be agitated with water rendered faintly alkaline by caustic soda, and indeed may be advantageously kept in contact with faintly alkaline water. The agitation with water is essential in the case of solvents liable to certain alcohol (e.g., ether, chloroform, amylic alcohol), the presence of which might seriously modify their action. In using immiscible solvents, it must be borne in mind that extraction is never theoretically perfect with a single treatment. The dissolved body is distributed between the two solvents in proportions which are probably dependent on the relative solu- bility of the substance in the two media, and the relative quantities of the two media employed. Thus, it may be sup- posed that if a substance be 99 times more soluble in chloroform than in water, and its aqueous solution be shaken with an equal ^ The principle appears to have been first adopted by Otto in 1856, who employed ether in his modification of S t a s ' process for the detection of poisonous alkaloids. In 1856, Rodgers and Gird wood employed the method with chloroform, and in 1861 Uslar and Erdmann recommended the use of amylic alcohol. In 1867, Dragendorff published his well- known elaborate scheme for the separation of plant-principles by immiscible solvents. .USE OF IMMISCIBLE SOLVENTS. 155 measure of chloroform, 99 per cent, of the whole substance will pass into the chloroform. On separating this layer, and again agitating the aqueous liquid with an equal quantity of chloro- form, 99 per cent, of the remaining substance will be dissolved, thus making the exhaustion practically complete. In the case of ether and amylic alcohol, the solubility of the solvent itself in the aqueous liquid is also an important consideration ; for, as ether is soluble in about ten times its measure of water, on agitating together equal measures of ether and an aqueous liquid, it may be assumed that one-tenth of the ether will be dissolved, and will remain in the aqueous liquid together with its one- tenth share of the alkaloid or other substance to be extracted. On separating the ethereal layer, and again shaking the aqueous liquid with an equal measure of ether, it may be considered that nine-tenths of the previously dissolved ether and its alkaloid will be recovered in the immiscible solvent. On the other hand, the ethereal layer is not wholly free from water, which may be expected to take up certain substances not soluble in anhydrous ether; but practically such traces of impurity are removed on agitating the ether with a limited quantity of water. Similar considerations of solubility apply to treatments with chloroform, but with considerably less force owing to its slight solubility in water and vice-versa; and in the case of petroleum-ether and benzene they have no practical bear- ing, as these solvents are almost abso- lutely insoluble in aqueous liquids. In making a proximate analysis by means of immiscible solvents, much of the success in practice depends on the care and skill with which the manipu- lation is conducted. The most con- venient apparatus for effecting the treatment consists of a pear-shaped (fig. 1) or cylindrical (fig. 2) glass separator, furnished with a tap below and a stopper at the top. The tube be- low the tap should be ground obliquely so as to prevent loss of liquid by imperfect delivery. Supposing that it be desired to effect the separation of a substance from an aqueous liquid by agitation with ether, the former is introduced into the sei)arator, of which it should not occupy more than one-third, acid or alkali added as may be desired, and next a volume of ether about equal to that of the aqueous liquid. The stopper is then A Fi^. 1. Fic(. 2. 156 REPARATION BY IMMISCIBLE SOLVENTS. inserted and the whole thoroughly shaken together for a minute or two, and then set aside. As a rule, the contents will readily separate into two well-defined layers, the lower of which is aqueous, and the upper ethereal. Sometimes sei)ai'ation into layers does not occur readily, the liquid remaining apparently homo- geneous, forming an emulsion, or assuming a gelatinous consistency. In such cases, separation may sometimes be induced by thoroughly cooling the contents of the separator. In the case of ether, the separation may usually be effected by adding an additional quantity of ether and re-agitating, or, when the employment of a sufficient excess of ether is inconvenient or impracticable, the addition of a few drops of alcohol, followed by a gentle rotatory motion of the liquid, will almost invariably cause separation to occur promptly. The tendency to form an obstinate emulsion is greatest when the aqueous liquid is alkaline, and is often very troublesome when chloroform, benzene, or petroleum-ether is substituted for ether. In such cases, the employment of a larger quantity of the solvent sometimes causes separation, but, when admissible, a better plan is the addition of ether. This answers very successfully for the isolation of strychnine, Avhich is nearly insoluble in unmixed ether, but readily soluble in a mix- ture of equal measures of ether and chloroform. This solvent is heavier than water, and is capable of very extensive appli- cation. Separation having taken place, the aqueous layer should be run ofi" by the tap into another separator, where it can again be agitated with ether to insure the complete removal of the body to be dissolved therein. The ethereal liquid remaining in the first separator should be shaken with a fresh quantity of alkalised or acidulated water, which is then tapped ofi" as before, and the remaining traces removed by treating the ether with a little pure water. This having in turn been run ofif to the last drop, the ethereal solution can next be removed by the tap, but a preferable plan is to pour it off from the mouth of the separator, taking care to avoid the draining of any drops of aqueous liquid from the sides of the glass. When amylic alcohol, benzene, or petroleum ether is employed, the manipulation is the same as that just described ; but when chloroform is used, or a mixture containing a considerable pro- portion of that solvent, the aqueous liquid forms the upper stratum, and the chloroformic solution can at once be removed by the tap. When the volume of fluid treated with the immiscible solvent SEPARATION BY IMMISCIBLfc SOLVENTS. 157 f i is very small, the syringe pipette shown in veniently substituted for a tapped separator. structed by drawing out a test-tube, so as prolongation, the orifice of which not to disturb the liquid in which it is immersed. A narrow test-tube fashioned into a handle at the upper part serves as a piston, a short length of india-rubber tubing uniting it to the outer tube, while allowing of easy movement both in a vertical and a horizontal direction. Another convenient form of separator, devised by W. C h a 1 1 a w a y, is shown in fig. 4. It is practically a small wash - bottle fitting, which is adjusted to the tube or cylinder containing the layers of liquid it is desired to separate. It is 3g. 3 may be con- It is readily con- to form a narrow should be turned up so as so arranged that the exit- I Fig. 3. tube (B) can be adjusted in height by sliding it through the india-rubber collar C, so as to bring the tumed-up end just above the junction of the two layers. On then blowing through the side-tube (A), the upper stratum is forced up the inner tube, and can be removed, almost to the last drop, without disturbing the lower layer. The following table shows the behaviour of various classes of organic substances when shaken in acidulated or alkalised solution with immiscible solvents, such as ether, chloroform, amylic alcohol, benzene, and petroleum ether. It must not be supposed, how- ever, that the immiscible solvents can be employed indifferently, as some of the bodies are readily removed by certain solvents, but are unaffected by others owing to their limited solubility therein. This is especially the case with the alkaloids and glucosides, and hence the table must merely be regarded as showing their general tendency, their special behaviour with the different solvents being deferred for fuller description later on. 158 SEPARATION BY IMMISCIBLE SOLVENTS. Table showing the behaviour of Organic Substances with Immiscible Solvents. On agitating the substance with water, acidulated with sulphuric acid, and a suitable solvent immiscible therewith (such as ether, chloroform, amylic alcohol, benzene, or petroleum ether), the following distribution will occur : — The Immiscible Later will contain hydrocarbons, oils, various acids, resins, colouring matters, phenols, glucosides, &c., which may be fui'ther separated by agitating the liquid with water con- taining caustic soda, when there will be obtained : — In the Immiscible Layer— Solid Hydrocarbons ; as paraffin, naph- thalene, anthra- cene. Liquid Hydrocar- bons ; as petrole um products,rosin-oil, benzene. Essential Oils ; as turpentine. Nitro - compounds; as nitrobenzene. Ethers and their Allies; as ether, chloroform, ethe- real salts, nitro- glycerin. Fixed Oils, Fats, and Waxes. Neutral Resins and Colouring Matters. Chlorophyll. Camphors; as laurel- camphor, borneol, raenthoL Alcohols insoluble or nearly insoluble in water ; as amyl and cetyl alcohols, cholesterin. Certain Glucosides, X rt e o II gas 5 c o ^ ^ S tH (BO ..- . C I's,--^ a.ss^5 a g'-g-E • • § s 2 o S a'S 15 ^ S § 'S a i £ O ftpnd-ii'Q c-^ E,3 CO © . . .5 ^.2:32 ?.= ;§§ a d.g li>.^:il||i'i'.a pq O Q W e Ph Ph 02 02 02 S ^5 ■» < >. o o o ^ "a ^--r -^ 55j g O -< CS ol -- -"^ '« 5;2 a rf «o:2^« OOP- I OOOOOPfifiHWOfSc? sah § ^. V. Meyer has suggested that the formation of the bases and other nitrogenised constituents of plants may be due in some cases to the action of hydroxylamine on aldehydic bodies. It is a curious fact that while the plant-bases and other natural products not unfrequently contain one or more methyl-groups, the ethyl-radical is not met with. VOLATILE BASES OF VEGETABLE ORIGIN. Certain plants contain bases which differ from the ordinary vegetable alkaloids, in being volatile, liquid at ordinary or only slightly raised temperatures, and in containing no oxygen. While resembling each other in the above respects, the volatile bases present little further resemblance. The volatile alkaloids are not numerous, being limited to the following bodies, and a few others which have been but imper- fectly investigated. a. Methylamine and Trimethylamine, already described (pages 9, 12). b. Conine and the associated alkaloids of hemlock. c. Lupinine and certain other alkaloids of lupines. d. Nicotine^ the volatile alkaloid of 1 b a c c o. e. Piturine^ the volatile alkaloid of p i t u r i, /. Loheline, the alkaloid of lobelia. g. Sparteine^ the alkaloid contained in broom. h. Spigeline, an alkaloid in Spigelia Marylandica. Piperidine, a volatile alkaloid said to exist naturally in pepper as a decomposition-product of p i p e r i n e, has already been- described (page 106). For the estimation of volatile alkaloids (e.g., c n i n e in hemlock, and nicotine in tobacco), A. L o e s c h (Jour. Amer. Ghem. Soc.) recommends that a weighed quantity of the substance should be boiled in water acidulated with hydrochloric acid, the residue pressed and washed with water. The solution and washings are evaporated to one-fourth, and then distilled with slaked lime (using a good condenser). When the liquid passing over is no longer alkaline to litmus, the distillate is exactly neutralised with sulphuric acid, evaporated to dryness at 100°, and the powdered residue exhausted with rectified spirit, which leaves the ammonium ALKALOIDS OF HEMLOCK. 171 sulphate undissolved, while the sulphate of conine (and other alkaloids) pass into the solution. The filtered liquid is evaporated to dryness and the residue skaken three times with caustic potash solution and ether, the ethereal liquid separated and shaken with a known volume of standard sulphuric acid, the ether distilled off or separated, and the excess of sulphuric acid determined by titration. By this process, Loesch found 5 '2 5 per cent, of nicotine in tobacco leaves, and 0"06 per cent, of conine in the common hemlock plant. Conine.^ Coniine. Conia. Conicine. C^Hi^N ; C,H,„(C3H,)N ; or CH, { 02^;^^'^'^ } ^H This base has the constitution of an a-normal-propyl-, piperidine (see page 1 64). Conine is the characteristic poisonous alkaloid of hemlock, Gonium maculatum. It occurs in all parts of the plant, in combination with organic acids, and in association with the following allied bases : — Base. Formula. 11 Specific Gravity. Ethyl-piperidine, . C7H16N: or C6H9(C2Hb)NH ... 142-145 |J =0-8674 Conine (Normal-) propyl-piperi- >- dine), ) CgHi^N ; or C6H9(CsH7)NH -2-5 167-170 1^=0-8625 Methyl-conine, . C9H19N ; or C6H9(C8H7)N(CH8) ... ... {i|5=0.846 Conhydrine, . CgHiyNO ; or C5H9(CHOH.CH2.CH8)NH 120-6 240(225 at 720 ... Paeudo-conhydrine, CgHirNO; or C5H9(CH3.CH20H.CH)NH 100-102 mm.) 229-231 ... Conine is an oily liquid, having a peculiar repulsive odour, ^ Conine has been prepared synthetically by the reducing action of sodium on a boiling alcoholic solution of ally l-pjTi dine, C5H4(C3H5)N, itself obtained from o-picoline and paraldehyde. The artificial base thus prepared is identical in all its properties vv^ith the natural alkaloid, except that it is optically inactive. But on introducing a crystal of the bitartrate of the natural alkaloid into a very concentrated solution of the bitartrate of the inactive bases, a gradual separation of the bitartrate of active conine occurs, the free base from which exhibits the same optical activity as natural conine. The mother-liquid contains a laevo-rotatory isomeric base (Laden burg, Ber., xix. 2578). 172 PROPERTIES OF CONINE. suggesting that of a long-used and foul tobacco-pipe. "When diluted with water, conine has a peculiar and characteristic "mousy" odour, perceptible in highly dilute solutions. A few drops of an aqueous solution containing only 1-50,000 of the alkaloid, if enclosed for a short time in a small test-tube, is stated byWormley to impart a marked mousy odour to the contained air. Conine may be distilled without change in an atmosphere of hydrogen, but undergoes slight decomposition at high temperatures in presence of air. It distils readily with vapour of water or alcohol, and volatilises sensibly at ordinary temperatures. Conine is optically active, its specific rotation being + 13°*8 for the sodium ray. Conine forms an unstable compound with 25 per cent, of water, the water being expelled by heating. Conine is soluble in about 90 parts of cold water, and is readily dissolved by alcohol, acetone, amylic alcohol, ether, chloroform, petroleum ether, and benzene. The alkaloid is removed with tolerable facility from its aqueous or alkaline solutions by agitation with either of the last five solvents, and may be recovered therefrom by shaking the resultant solution with dilute acid. Conine dissolves sulphur, but not phosphorus nor calcium chloride. Conine is colourless when freshly prepared, but becomes yellow and ultimately resinoid by keeping.^ It is a strong base, the aqueous solution being powerfully alkaline in reaction, and neutralising acids perfectly. The salts are colourless and odour- less, but the peculiar odour of the free base is immediately developed on adding a fixed alkali in excess. If a beaker moistened with fuming hydrochloric acid be inverted over a watch-glass containing a drop of free conine, white fumes will be produced, and the alkaloid will be con- verted after a time into a crystalline hydrochloride^ C^^j^ ^C\. (Nicotine gives an amorphous hydrochloride.) The hydrochloride is also obtained as a brilliant crystalline mass by dissolving conine in anhydrous ether, and passing dry hydrochloric acid gas through the solution. The salt is very soluble in water and alcohol, but insoluble in ether. It can be heated to 90° C. without decom- position or loss of weight. It melts at 218°. The hydriodide of conine is anhydrous. It can only be obtained crystalline by the use of pure hydriodic acid free from any trace of iodine. By slow evaporation the salt is obtainable in large flat needles, which sublime when gently heated in vacuo. ^ According to S c h o rm, pure conine does not undergo any change by exposure to light {Pharm. Jour., [3], xii. 363). REACTIONS OF CONINE. 173 On adding a large excess of strong hydrochloric acid to conine, a pale red tint is produced, which gradually deepens in colour. Nitric acid acts similarly. Sulphuric acid produces no immediate change with conine, but the mixture gradually becomes purple- red, and then olive-green. On exposing a drop of conine to the vapours of bromine (avoiding excess), it becomes rapidly converted into a mass of white crystals. This behaviour is regarded by Watts as a proof of the purity of the alkaloid. By the treatment of conine with chromic acid mixture, normal butyric acid is produced. The reaction may be employed as a test for conine, as butyric acid has a highly characteristic odour, and can be readily distilled ofif and further examined. Butyric acid also results from the oxidation of conine by bromine-water or nitric acid, while permanganate converts it into picolinic acid. On distillation of conine hydrochloride with zinc-dust, or the free base with zinc chloride, hydrogen is evolved and a-propyl- pyridine or conyrine, Cr^TlJfi^'K^)'N, formed. This base boils at 166°-168°, and is reconverted into conine on treatment with hydriodic acid. (By prolonged treatment with hydriodic acid conine is converted into ammonia and octane, CgH^g.) Mercuric chloride produces with conine a white amorphous precipitate, readily soluble in hydrochloric or acetic acid. (Nico- tine gives a crystalline precipitate.) With potassio-mercuric iodide, conine gives a voluminous curdy precipitate. Silver nitrate gives a brown precipitate of argentic oxide with free conine, the colour afterwards changing to black. (Nicotine gives a white precipitate with silver nitrate, turning dark on exposure to light.) Conine cMoroplatinate is a readily soluble salt. Conine gives a yellow precipitate with phosphomolybdic acid, and an orange precipitate with potassio-iodide of bismuth. Picric acid does not precipitate conine from solutions con- taining less than 1 per 1000 of the alkaloid, but nicotine is precipitated from solutions fifty times more dilute. Conine is said to coagulate albumin, thus differing from nicotine. If conine be dropped into a solution of alloxan, an intense purple-red coloration is gradually produced, and white needles separate which dissolve with purple colour in cold potash solution. The alkaloids occurring with conine in hemlock and its prepara- tions are precipitated by Mayer's reagent, picric acid, and iodine from solutions considerably more dilute than those from which conine itself is thrown down, CoNHYDRiNE lias the probable constitution of a piperidyl- 174 DERIVATIVES OF CONINE. e t h y 1 a 1 k i n e, C5H9(CHOH.CH2.CH3)NH. It presents a close resemblance to t r o p i n e, CgHjgNO, both in composition and chemical behaviour, a fact which suggested to A. W. H o f m a n n the probability that it was the product of the hydrolysis of a base allied to atropine. From the alkaline liquid left after the distillation of conine and conhydrine, H o f m a n n obtained, by acidulation and extraction with ether, caffeic acid, CgllgO^, a body liaving the constitution of a dihydroxy-cinn amic acid. Conhydrine may be separated from commercial conine, in which it is not unfrequently present, by cooling the liquid down to 5° C, filtering through glass wool, and washing the separated crystals of conhydrine with petroleum ether, in which it is but sparingly soluble. Pseudoconhydrine is a base isomeric with con- hydrine, but probably containing hydroxy-isopropyl (Ladenburg, Ber., xxiv. 1671). Conhydrine forms colourless glittering crystals, moderately soluble in water, but very soluble in alcohol and ether. It does not react with nitrous acid, has an alkaline reaction, and is a feeble narcotic poison. According to "Wertheim, hemlock contains only 5 to 6 parts of conhydrine for every 100 of conine. CoNiCEiNES, CgHjgN. These bases were obtained by A. W. H f m a n n by the action of oxidising agents on conine, or of dehydrating agents on conhydrine. When molecular proportions of conine hydrobromide and bromine are mixed, the bromo-deriva- tive, CgHj^KHBr.Brg, is obtained. By the regulated action of caustic soda this yields CgH^^XBr, which by treatment with sul- phuric acid is decomposed into hydrobromic acid and a-coniceine, which is a colourless liquid of '893 specific gravity at 15°, boiling at 158°, and slightly soluble in water. In odour it closely resembles conine, but is said to be five or six times as poisonous ! It is a tertiary base of strong alkaline reaction, and forms crystal- isable salts. The picrate forms yellow needles melting at 226°, nearly insoluble in cold water, and very slightly soluble in alcohol, a-coniceine is partially reduced to conine by heating under pressure with fuming hydriodic acid and phosphorus. y-coniceine is obtained by decomposing the bromo-derivative CgH^gNBr by an alkali. It is a colourless liquid lighter than water, boiling at 173°, distilling with steam, and said to be twelve times as poisonous as conine ! It is only slightly soluble in water, but the solution is strongly alkaline. y-coniceine is a secondaiy base (pages 1, 7) yielding crystalline, volatile salts with acids, and a characteristic double salt with stannic chloride, BgHgSnClg, which forms large crystals. ^-coniceine is obtained together with a-coniceine by the action of phosphoric anhydride or fuming hydrochloric acid on conhydrine : — CgHi^NG = CgH^gN -|- HgO. It forms very vola- POISONING BY HEMLOCK. 175 tile, colourless needles, melts at 41° and boils at 168°. It is a secondary base of conine-like odour, and is a less active poison than the a-modification. Poisoning by Conine and Hemlock. Conine is an extremely powerful paralytic poison, which acts on the motor nerves; one drop is a distinctly poisonous do^e, while ten drops may be fatal. The symptoms produced by hemlock and conine are not uniform, and cases of poisoning are not numerous. Stupor, coma, and slight convulsions have been noticed, while in other cases the chief effect has been paralysis of the muscular system, especially of the legs. The pupils are somewhat dilated. After death the lungs are found filled with fluid blood and of a dark colour, and the stomach and intestines somewhat congested. The posi-morteim appearances are not characteristic. In toxicological inquiries the viscera and contents of the stomach should be treated as described under strychnine, the purified extract being agitated with soda and ether instead of ammonia and chloro- form. From the ether, the alkaloid may be recovered by allow- ing the solvent to evaporate spontaneously in a cool place, or extracted as a salt by agitating the ether with dilute hydrochloric acid. From the purified salt of conine thus obtained, the free base may be again liberated by adding soda, and recognised by the mousy odour of hemlock developed immediately or on warming the liquid. Conine may also be isolated from the viscera by the method used for the assay of hemlock. Otto in one case met with a volatile ptomaine, which was very poisonous, but differed from conine in its reaction with platinic chloride. The seeds of Lupimis luteus (page 177) contain alkaloids somewhat resembling conine, but which do not yield the characteristic crystalline hydrochloride. Other of the umhelliferce besides conium are possessed of poisonous properties, but it does not appear that conine has been proved to be the active principle.^ ^ (EnantJie crocata, or hemlock wateirdropwort, is described by A. S. Taylor as one of the most virulent of English vegetable poisons. The leading symptoms produced are rapid insensibility, bloated and livid coun- tenance, convulsive movements, stertorous breathing, dilated pupils, and bloody foam about the mouth and nostrils. Gicuta virosa, water-hemlock or cowbane, produces symptoms similar to the above, including the foaming at the mouth* It is said to contain c i c u t i n e. Sium latifoUum and S. angustifoUum have been mistaken for water-cress, with fatal results. ^thusa Cynapium, the lesser hemlock or fool's parsley, appears 176 ASSAY OF HEMLOCK. Assay op Hemlock and its Preparations. Conine exists in all parts of the common or spotted hemlock, Conium maculatum (French, la Cigue ; German, der Schieliwj). It appears to be most abundant in the fruit, the proportion increas- ing with the maturity of the seeds. In hemlock leaves, R. K o r d e s found 0*24, and in the fruit 0*49 per cent, of alkaloid. For the extraction of conine from hemlock, J. S c h o r m (Ber., xiv. 1765) recommends that the fiuit should first be swelled by hot water, and then moistened with a strong solution of sodium carbonate. The product is treated with steam, under a pressure of three atmospheres, as long as the distillate has an alkaline reaction, when it is neutralised with hydrochloric acid and evaporated to a weak syrup, which is shaken with twice its measure of strong alcohol and filtered from the precipitated ammonium chloride. The filtrate is distilled at 100°, a calculated amount of caustic soda ley added, and the mixture agitated with ether. (The residual aqueous liquid developes trimethylamine on prolonged standing, especially in summer.) The ethereal solution deposits large crystals ofconhydrine when strongly cooled. This base is somewhat sj)aringly soluble in ether, and on distilling the solution passes over with the ether. The conine remaining in the retort is dehydrated with potassium carbonate, and purified by fractional distillation. The first 10 per cent, boils between 110° and 168° C, and is very impure. The next 60 per cent., boiling between 168° and 169°, is pure conine; while the next 20 per cent., boiling between 169° and 180°, is impure. The thick dark liquid left in retort contains conhydrine. A purer product, but somewhat lower yield, is said to be obtained by exhausting the hemlock fruit with acetic acid, and evaporating the solution to a syrup in a vacuum. Magnesia is then added, and the mixture agitated with ether, which extracts the alkaloid. Many specimens of conium leaves and seed are almost inert from the loss of their volatile active constituent, and hence a method of assay is of considerable importance, and ought to have a place in the Pharmacopoeia. For the determination of the conine and associated alkaloids in hemlock, R. A. Cripps {Pharm.. Jour., [3], xviii. 13, 511) recommends the following process : — A weight of 5 grammes of the finely-powdered fruit is mixed with an equal weight of sand, and extracted with a mixture of 25 c.c. of nearly absolute alcohol, to contain an energetic poison, though this has been disputed by H a r 1 e y (^< Thomas's Hospital Reports, new series, iv. 63 ; x. 257), and also by Tanret, who believes the erroneous statements respecting it to have arisen from a con- fusion of the plant with Conium maculatum, which it closely resembles. ASSAY OF CONIUM PllEPARATlONS. 177 15 c.c. of chloroform, and 10 c.c. of a saturated solution of dry- hydrochloric acid gas in chloroform. The liquid is separated from the marc^ and agitated with two separate quantities of 25 c.c. of distilled water. The aqueous liquid now contains the conine as hydrochloride. It is shaken once with chloroform, then rendered alkaline with caustic soda, and extracted three times by agitation with chloroform. The chloroform is washed by agitation with alkaline water, and is then run into a solution of hydrochloric acid gas in ether. This is evaporated in a current of air, and the residue dried at a temperature not exceeding 90° C. The conine hydrochloride obtained should be crystalline, and almost perfectly white. From its weight the proportion of conine can be calculated, 163'5 of the hydrochloride representing 127'0 of the base. If, after weighing the residue, the hydrochloric acid be determined by titration with silver nitrate, using potassium chromate as an indi- cator, the difference will be the weight of alkaloid, and the result should closely correspond with that previously calculated. The foregoing process may be shortened by agitating the washed chloroformic solution of the conine as liberated by caustic soda with water, and gradually adding decinormal hydrochloric acid until a slight acid reaction to methyl-orange is developed, which does not disappear on again shaking. Each c.c. of decinormal acid used represents 0'0127 gramme of alkaloid, in terms of conine. Petro- leum spirit may be substituted for the chloroform. For the estimation of the alkaloids in Tincture of Oonium, Fair and Wright (Pharm. Jour., [3], xxi. 857) evaporate 50 c.c. of the preparation to a low bulk at 100° C. with 1 c.c. of normal sulphuric acid. The residual liquid is diluted somewhat, and twice shaken with chloroform. It is then rendered alkaline with ammonia, and the liberated alkaloids shaken out with chloroform. The chloroformic solution is freed from traces of ammonia by agitation with water, separated and run into a solution of dry hydrochloric acid gas in chloroform, taking care that the orifice of the separator dips below the surface of the acid chloroform, which is then evaporated, and the residue dried at 90° and weighed, as recommended by Cripps. The proportion of total alkaloid contained in the tincture of conine, as assayed by this process, is from 0'07 to 0*10 per cent. The proportion in the extract ranges from J to nearly 3 per cent. ^ The exhaustion should be proved to be complete, by treating the marc with water, and testing the solution with iodine and with Mayer's solution, neither of which should produce more than the faintest turbidity ; and the dried marc should give a barely perceptible odour of conine when warmed with caustic soda. VOL. III. PART II. M 178 LUPTNTNE. Lupine Alkaloids, From the different species of lupine several alkaloids have been isolated, some of which, at any rate, belong to the class of volatile alkaloids, and in their odour and other characters appear to be related to conine. LupiNiNE, G^iH^oNfi^' 0^ C2iH38N2(OH)2 As isolated by G. Baumert from the seeds of Lupinus luteus, lupin ine is a readily crystallisable base, melting at 67°'5-68°*5, and boiling with some decomposition at 255°-261°. In a stream of hydrogen it distils unchanged at 255°— 257°, and is also volatile with steam. Lupinine has a pleasant apple-like odour and an extremely bitter ta^te, the latter character extending to its salts. It has a paralysing effect on the nerve-centres. Lupinine is Isevo-rotatory, easily soluble in cold water and alcohol, but less soluble in warm water. Erom its aqueous solution it is separated by excess of caustic alkali. Lupinine dissolves readily in ether, chloroform, and benzene. Car- bon disulphide dissolves the base while acting chemically upon it. Lupinine is highly caustic, and is a strong base, liberating ammonia from its salts and fuming with hydrochloric acid. B(HC1)2 forms large rhombic crystals. BHgPtClg is crystalline and soluble in water. The aurochloride, B(HAuCl4)2, forms needles, difficultly soluble in water, but readily in alcohol. The nitrate, 'QQl^O^^^ forms rhombic crystals, very soluble in water and alcohol. Metallic sodium dissolves in melted lupinine with evolution of hydrogen, forming a sodium-derivative, decomposed by water into lupinine and sodium hydroxide. When heated with acetic anhydride, lupinine yields 0<^^^^{G^^O\, as an oil, insoluble in water and very easily saponified. When lupinine is heated to 150°- 180° for ten or twelve hours with fuming hydrochloric acid, or the hydrochloride to 175° with phosphoric anhydride, it yields anhydrolupinine, 0211138X20, as a highly oxidisable fluid base, smelling like conine. BHgPtOlg forms red quadratic tables, easily soluble in water and dilute alcohol. Dianhydrolupinine, OgjHggNg, results when lupinine is heated with fuming hydrochloric acid to 200° 0. It is a highly oxidisable oil, boiling at 220°, and forming a chloroplatinate, crystallising in dark red needles. Oxylupinine, C^^A^o^j^b^ ^^ formed, together with anhydrolupinine, by the action of phosphoric anhydride on lupinine hydrochloride. It is a yellowish, disagree- able smelling oil, boiling with some decomposition at 215°. Arqininb, OgH^^N^Og, is contained in the seeds of L. luteus which have germinated in the dark. It forms crystalline salts, evolves nitrogen with nitrous acid, and yields urea when boiled with baryta-water. LUPINE ALKALOIDS. 179 LuPiNiDiNB, CgH^gN, is a base found by B a u m e r t in the yellow lupine. It forms a volatile, oxidisable, viscous oil, having an odour of hemlock. It is intensely bitter and feebly poisonous, producing symptoms like those of curare. Lupinidine forms a crystalline hydrate, BjHgO, very insoluble in water. The salts are crystallisable. No acetyl-derivative is obtainable. LuPANiNE, C15H24N2O, is an alkaloid obtained by M. H a g e n {LieUgs Annalen, ccxxx. 367 ; Jour. Ghem. Soc, 1. 163) from the seeds of the blue lupine, Lupinus angusH/oUus, which are stated not to contain lupinine or lupinidine. It is described as a pale yellow, honey -like syrup, with green fluorescence, intensely bitter taste, and an unpleasant odour like that of hemlock. Lupanine does not boil at 290°, even under the reduced pressure of 130 mm. It has a strong alkaline reaction, attacks the skin, expels ammonia from its salts, and forms with hydrochloric acid white fumes of the hydrochloride. With excess of cold water, lupanine forms a turbid solution, from which the base is almost entirely separ- ated on heating. It dissolves with difficulty in cold alcohol, but readily in ether, chloroform, and petroleum spirit. Lupanine hydro- chloride^ BHCl-f 2aq., forms hygroscopic, quadratic crystals, melting at 127°, and soluble in alcohol but not in ether. BHgPtClg is not distinctly crystalline. BHAuCl^ forms golden needles, insoluble in water, alcohol, or ether. From solutions of its salts, lupanine is precipitated by caustic potash and soda, but not by ammonia. From the seeds of Lupinus alhus, C a m p a n i isolated a poisonous liquid alkaloid, boiling at 210°-218°. From the same source B e t e 1 11 obtained a crystallisable base. According to 0. Ke liner (Bied. Centr.^ x. 97) lupine seeds can be deprived of the whole of their bitter constituents, and rendered much more palatable and wholesome, by soaking them in water for twenty-four hours, steaming them for one hour, and then washing them for two days. Ktihn has shown that the substances which cause lupine sickness are destroyed by steaming. Nicotine. Nicotia. CjoHi^Ng ; or CgHyN.CgHyN. Nico-tine has the constitution of ahexahydro-dipyridyl (see page 164). It is the poisonous basic principle of tobacco, in which it exists combined with malic and citric acids (compare page 184), in proportions varying within very wide limits. Pure nicotine is a colourless, oily fluid of I'Oll specific gravity at 15° C. On prolonged exposure to air it becomes yellow, and eventually resinoid. It has a sharp caustic taste, is intensely poisonous, and has a strong and unpleasant odour, recalling that of tobacco. Nicotine boils at about 250° C, with partial decom- 180 CHARACTERS OF NICOTINE. position, but it distils readily with the vapour of water or alcohol, and volatilises to a notable extent at the ordinary temperature. Nicotine absorbs moisture from the air, and evolves heat when mixed with water, diminution in volume simultaneously occurring.^ Skalweit (Ber., xiv. 1809) has given the following figures showing the specific gravity of mixtures of nicotine and water. His results point to the existence of a hydrate of nicotine. Mcotine. Water. Specific Gravity at lb' a 100 1-011 100 5 1-017 100 10 1-024 100 20 1-030 100 30 1-034 100 40 1-037 100 50 1-040 100 60 1-038 100 70 1-033 Nicotine has a powerful laevo-rotatory action on polarised light, the value of Sj, in 20 per cent, aqueous solution being, according to Pribram, — 161°*55. The rotation diminishes rapidly but irregularly by further dilution. Thus for a 4 per cent, solution the value S^ is — 77°"03, while below this strength an increase is observed, S^ being — 79°'32 for a solution of 0*8826 specific gravity. The rotation is affected by time, not reaching its maximum for 48 hours (Ber., xx. 1840). The aqueous solution of nicotine is powerfully alkaline in reaction. The nicotine is partially separated by addition of excess of caustic potash or soda (compare pyridine). Nicotine in aqueous solution, and in the absence of other free base, can be determined by titration with standard acid and methyl-orange. Nicotine forms two classes of salts. The m on acid salts are stable and neutral to litmus and methyl-orange, but the diacid salts have an acid reaction. Most of the salts of nicotine crystallise with difficulty. The acid tartrate, C-^QK^^1^2i^^^QOQ\-\-2a.q., is an exception, and forms handsome tufts when ether is added to its alcoholic solution. Detection and Determination of Nicotine. Alcohol dissolves nicotine in all proportions, and on evaporating 1 When water is added to solution of nicotine containing less than 20 per cent, of base, the mixture becomes turbid and clears only on long standing. On heating to 40° the liquid clears rapidly, but becomes again turbid when cooled or further heated to 60°. Between 50° and 60° the turbidity amounts to milkiness, which disappears when the liquid is cooled below 50°. At 70* the nicotine separates in part as an oily layer. REACTIONS OF NICOTINE. 181 or distilling the solution the alkaloid is found chiefly in the first fractions. It is extracted from its aqueous alkaline solutions by agitation with ether, chloroform, benzene, amylic alcohol, or petroleum spirit, and may be recovered from the solvent by separating and agitating with dilute acids. If oxalic acid be employed, the resultant solution may be evaporated to dryness and treated with alcohol, which dissolves the nicotine oxalate while leaving any ammonium oxalate undissolved. After again removing the alcohol by evaporation, the nicotine may be liberated from the warm liquid by adding excess of caustic soda, when the characteristic tobacco-like smell of nicotine will be observed, and the alkaloid can be obtained pure by distilling the liquid with water, or agitating it with ether and allowing the separated solvent to evaporate spontaneously in a cool place. Treated with nitric acid, nicotine yields a thick reddish liquid. Sulphuric acid produces no change in the cold, but a brown colour is developed on heating. On dissolving nicotine in dilute hydrochloric acid, and adding platinic chloride, nicotine chloroplatinate, C^QHj^NgjHgPtClg, is thrown down as a sparingly soluble, yellowish, crystalline com- pound. The precipitate is soluble in hot water, especially in presence of free hydrochloric acid. Addition of alcohol increases the delicacy of the test, and the formation of the precipitate is much facilitated by stirring the liquid. Ammonia gives a similar reaction, but c o n i n e yields no precipitate with platinic chloride. Picric acid, if added in excess to solution of nicotine, throws down nicotine picrate as an amorphous yellow precipitate, which rapidly changes to a mass of crystalline tufts, even in presence of foreign organic matter. Nicotine is precipitated by Mayer's reagent (page 138) from very dilute solutions ; and, by operating in strongly acid liquids, Zinoffsky obtained very good quantitative results. The formula of the precipitate is CjoH^^gNgHgl^, and 1 c.c. of the reagent repre- sents 0-00202 gramme of nicotine. On adding mercuric chloride to a solution of nicotine a white crystalline precipitate is produced, soluble in dilute hydrochloric or acetic acid. This is the most characteristic reaction of nicotine. Strychnine produces a similar precipitate, nearly insoluble in acetic acid. Many other alkaloids are precipitated, but the com- pounds are almost invariably amorphous. This is the case with the precipitate produced by conine, which is almost the only alkaloid which will distil over with nicotine on boiling the solution with a slight excess of caustic soda. Ammonia, however, behaves like nicotine, and must, if necessary, be separated before applying the 182 DETERMINATION OF NICOTINE. test. Ammonia is sharply distinguished from nicotine, conine, and lobeline by adding a solution of iodine in iodide of potassium to the slightly acidulated solution of the base. Ammonia produces no change, but with either of the vegetable alkaloids a brown or brownish red precipitate will result. Iodine solution will detect 1 of nicotine in 250,000, and is the most delicate reagent known for the alkaloid. Solutions of nicotine are not precipitated by chromates, ferro- cyanides, ferricyanides or thiocyanates, nor by gallic acid. With gallotannic acid an aqueous solution of nicotine yields a white, amorphous precipitate, which readily dissolves on cautious addition of hydrochloric acid, but is again precipitated by further addition of acid, and is then insoluble even in a large excess. Tannate of nicotine is readily soluble also in acetic and nitric acids, but is not reprecipitated on adding an excess. A variety of processes have been devised for the determination of nicotine in tobacco and its preparations. The problem is com- plicated by the presence of ammonium salts, by the difficulty of completely extracting nicotine from aqueous liquids by agitation with immiscible solvents, and by the tendency to form an emulsion when these are used, owing to the presence of pectinous mattei; The methods proposed have been reviewed by J. B i e 1 {Pharm. Zeit. Russ.y xxvii. 3; Analyst, xiii. 97), who recommends the following process, which is a modification of that proposed by Kiss ling: — 100 grammes of powdered tobacco-leaves, or 10 to 20 grammes of extract of tobacco, are mixed with slaked lime and distilled in a current of steam until the condensed steam is no longer alkaline. The distillate, which will measure about I litre, is rendered faintly acid with dilute sulphuric acid, evaporated to 50 c.c, made alkaline with caustic soda, and agitated six times with ether, using 20 c.c. each time. Biel then distils off the greater part of ether slowly, adds excess of decinormal sulphuric acid, and titrates back with decinormal soda, using rosolic acid as an indicator. The object in distilling off the ether is to get rid of any traces of ammonia which may be present ; but it is difficult to do this without risking the volatilisation of some of the nicotine. It is preferable to titrate the unconcentrated ethereal solution by gradually adding decinormal sulphuric acid, using methyl-orange as an indicator, and agitating between each addition. Each c.c. of decinormal acid neutralised represents 0*0162 gramme of nicotine. The results will be high if ammonia be present, and in such case the neutralised aqueous liquid should be separated from the ether, and evaporated to dryness at 100°. The residue is wei(^hed and treated with absolute alcohol, which will dissolve the sulphate of nicotine, while any ammonium sulphate will be POISOKING BY NICOTINE. 183 left insoluble, and its weight can be deducted from the weight of the mixed sulphates previously found, the difference being the sulphate of nicotine. The result may be confirmed by adding phenol- phthalein to the alcoholic solution of nicotine sulphate and titrating with decinormal alkali, which will react just as if the sulphuric acid were uncombined. From Conine, nicotine is distinguished by its odour, by being heavier instead of lighter than water, and by the reactions with hydrochloric acid gas, mercuric chloride, argentic nitrate, platinic chloride, and picric acid (see above, and page 181). Poisoning by Nicotine and Tobacco. Nicotine is one of the most violent poisons known. Only a few instances are on record of poisoning of the human subject by the pure alkaloid, but the effects of tobacco, which owes its poisonous properties entirely to nicotine, are well known.^ Impure solutions of nicotine and infusions of tobacco are employed as insecticides. "The usual effects of a poisonous dose of tobacco, when taken into the stomach, are confusion in the head, paleness of the coun- tenance, vertigo, nausea, severe retching and vomiting, heat in the stomach, great anxiety, a sense of sinking at the pit of the stomach with extreme prostration, trembling of the limbs, and sometimes violent purging. The pulse is small, feeble, and almost imperceptible ; the respiration difficult, and the skin cold and clammy ; the pupils are generally dilated, but sometimes con- tracted, and the vision is usually more or less impaired. Death is often preceded by convulsions and paralysis " (T. G. "W o r m 1 e y, Micro-chemistry of Poisons). In toxicological investigations, nicotine may be isolated from the viscera in the same manner as conine (pages 170, 175). An alterna- tive method is to digest the suspected matters with water acidulated with acetic acid, and treat the filtered liquid with excess of lead acetate. The liquid is again filtered, the lead removed from the filtrate by passing sulphuretted hydrogen, and the clear solution treated with caustic soda, separated from any precipitate, and distilled, when a fluid having the odour and exhibiting the reactions of nicotine will be obtained. Any supposed nicotine which may be isolated should be tested by placing it on the tongue of a young rabbit or small bird, when tremors, paralysis, and ^ "When tobacco is smoked, the greater part of the nicotine is converted into pyridine and other pyrogenous compounds, and the entire decomposition of the nicotine is sometimes asserted ; but M e 1 s e n s appears to have fully proved the presence of unchanged nicotine in tobacco smoke in a proportion equal to about one-seventh of that present in the original tobacco (compare page 193). 184 COMPOSITION OF TOBACCO. convulsions will rapidly ensue. Nicotine appears to be unchanged by putrefaction, and hence may be detected in the tissues long after death. Tobacco (French, le Tahac ; German, der Tahak), Tobacco is the dried leaf of Nicotianum Tabacum and allied species.^ According to S. W. Johnson, a good crop of tobacco, yielding 1260 lbs. of dry leaf and 1110 lbs. of dry stalk, removes from the soil the following constituents in lbs. per acre : — Constituents. so,, . . . . Ms CaO MgO, .... K2O NaaO Sum of Ash Constituents, Nitrogen, Leaves. 14 n 73 17 71 5 206 Stalks. 15 15 2 47 10 95J Total. 17 22rJ 88 19 118 15 SOli 82 As the stalks are returned to the land, tobacco is not a very exhausting crop, but requires abundant manuring, since the period of growth does not exceed three months. Hence, rye may be advantageously sown as soon as the tobacco is off, and ploughed in as a green crop when cultivation for tobacco commences. Besides cellulose, albuminoid compounds, pectic acid, gum- resins, and other ordinary plant-constituents, the leaf of tobacco contains a peculiai volatile, crystalline principle called nico- tianin or tobacco-camphor, to which the formula ^23^32-^2^3 ^^^ been attributed. Tobacco also contains the volatile alkaloid nicotine, which is apparently peculiar to the genus. This base exists in combination with malic acid, but the presence of citrates, acetates, and oxalates has also been established.^ Fresh tobacco-leaves (especially the midribs) contain a notable proportion of nitrates, but these salts are said to disappear during the process of fermentation to which manufactured tobacco is subjected. This fermentation has for its object the destruction or modification of some of the natural 1 The genus Nicotiana contains more than 70 species. N. Tabacum yields the tobacco of Havana, Cuba, France, Holland, Belgium, &c. N. rustica furnishes East Indian tobacco, and the kinds known as Latakia and Turkish tobacco. Tumbekior Persian tobacco is the product of N. Persica. * From 100 grammes of dried tobacco-leaves, G u p e 1 obtained from 3 to 4 grammes of acid malate of ammonium. J. Takayama {Chem. News, 1. OKGANIC ACIDS IN TOBACCO. 185 -constituents, and the formation of " ferment oils," which probably •contribute to the aroma, especially when saccharine matter, 300) obtained the following percentage results by the analysis of Japanese tobacco : — Nagato. Shimozuki. Settzu. Osumi. Water, 6-41 10-01 7-63 13-18 Ash, . 15-76 8-45 20-71 9-80 Nicotine, 2-45 3 02 3-92 1-89 Acetic acid 0-05 04 0-01 08 Oxalic acid, trace 0-27 0-25 trace Malic acid, 0-79 102 183 2-98 Citric acid, 0-62 0-59 0-92 0-89 Pectic acid, 1-24 6-84 7-42 2-35 In the above analyses, the nicotine was extracted by ammoniacal ether, the solvent distilled off, and the nicotine in the residue determined by titration. For the acetic acid, the powdered tobacco was moistened with water and tartaric acid, and distilled in a current of steam, the acetic acid being determined in the distillate. For the fixed organic acids, 10 grammes of the sample was moistened with sulphuric acid in the quantity requisite to combine with the bases (as indicated by the carbonates in the ash), and exhausted with ether. From the ethereal solution the acids were extracted by a small quantity of water, the separated aqueous liquid rendered alkaline with ammonia, acidulated with acetic acid, and the oxalic acid precipitated by adding calcium acetate. To the filtrate, a dilute solution of lead acetate was gradually added, until a test quantity of 1 c.c. of the supernatant liquid gave, on further addition of lead acetate, a precipitate which was completely soluble in a few drops of acetic acid. The liquid was then filtered, and the precipitate of lead citrate washed with water containing a little lead acetate and acetic acid, and then with alcohol, the washings being kept separate. The citric acid was deduced from the weight of lead oxide left on igniting the precipitate. From the filtrate, the malic acid was precipitated by excess of lead acetate solution, and its amount deduced from the weight of lead oxide left on ignition. The washings from the precipitate of lead citrate were boiled to expel alcohol and treated with excess of lead acetate, the precipitate being regarded as a mixture of lead citrate and malate in -equal proportions (compare Vol. I. page 434). The pectic acid was determined by exhausting 10 grammes of tobacco with rectified spirit containing one-fourth of its volume of concentrated hydrochloric acid. The residue was washed with spirit till the hydrochloric acid was wholly removed, and then treated with a solution of a known weight of ammonium oxalate, by which the pectic acid was dissolved. After digesting for two hours at 35°, the liquid was filtered, the residue washed, and the filtrate diluted to 1 litre. An aliquot part of this was precipitated by calcium acetate, and the precipitate washed and dried at 100°. The weight of lime left on igniting the precipitate was then ascertained. The weight of CaO and the oxalate in the precipitate being known, the pectic acid corresponded to the difference. 186 MANUFACTURE OF TOBACCO. liquorice or alcohol is added during the maceration to which the tobacco is subjected.^ As sold by the farmers, the tobacco-leaves contain about 30 per cent, of water. When the fresh leaf is simply dried, the product is yellow, the brown colour of commercial tobacco being due to the regulated fermentation already alluded to. The un- manufactured tobacco imported into England is converted into roll or spun tobacco, cut tobacco, and cigars, the refuse being used for making snuff. In the manufacture of roll-tobacco, the leaves are moistened with water, spun into various sizes of twist, made up into rolls, and pressed. The liquid or juice which exudes is used as a sheep-dip. Cut tobacco is made by moistening the leaves, cutting them to the required size, and drying on plates ; or it may be made into cakes first, and after- wards cut. The Excise regulations prohibit the use of any foreign matter in manufacturing tobacco, besides water and a little oil. Hence, except in the proportion of water, which is not allowed to exceed 35 per cent, (as estimated by drying at 100° C), there is no tangible diiference between manufactured tobacco and the dried leaves imported. The proportion of nicotine in tobacco does not appear to be an index of the quality. J. Clark {Jour. Soc. Chem. Ind., iii. 554) has published the percentages of ash yielded by the ignition of twenty-one authentic In 100 Parts of the Dry Substance. Total Ash. Soluble Ash, "Alkaline Salts." Sand. Whole Leaf -.— Highest Lowest, Average, Lamina :— Highest, .... Lowest, Average, . . . . Midrib :— Highest Lowest, ... Average 30-80* 13-79 20-32 31-07 * 12-47 19-21 80-37 * 15-44 21-92 11-37 2-40t 6-47 8-99 l-66t 4-98 20-01 4-63 11-41 12-32 ♦ 0-13 2-48 14-41* 0-09 2-86 4-91* 012 1-15 * Paraguay Tobacco. t Chinese Tobacco. samples of representative tobacco-leaves. The table is an abstract of his figures, which in all cases refer to the leaf dried at 100° C ^ Schizomycetes occur in fermented tobacco in large numbers, but the number of species is very limited. Trial experiments by E. Such si and, with foreign ferments on German tobacco-leaves, yielded a tobacco not recog- nisable as of German origin. ASH OF TOBACCO. 187 As the composition of the laminae and of the stem or midriTj of the leaf differ materially, these were carefully separated before analysis. E. Quajat {Bied. Centr., 1880, p. 345) found the aah of fourteen samples of dry tobacco (including both superior amd common kinds) to range from 31*03 per cent, in a Bassano sample to 17*11 in Virginian and 16*78 per cent, in Turkish. He con- siders that the quality of tobacco varies inversely with the ash, but N e s s 1 e r recognises no relation between the two. Irby and Cabell (Ghem. News, xxx. 117) have published the figures obtained by the analysis of six typical samples of Virginian tobacco. All were in the leaf state, free from stalk, but retaining the midrib. No. 1 was light yellow tobacco, " coal-cured wrappers" for cigars ; No. 2, light yellow, " fine smoking" tobacco ; No. 3 was medium brown colour, " sweet fillers" for cigars ; No. 4 was dark, "Austrian and Italian cigar wrappers;" No. 5, dark "English shipping;" and No, 6, dark, "exported to France for snuff." These samples when air-dried yielded : — No. 1. No. 2. No. 8. No, 4. No. 5. No. 6. Moisture, per cent., Ash, total, per cent, on tobacco, . „ Soluble in HCl, per 100 of ash, „ Sand and charcoal, „ „ „ Carbon dioxide, „ ,, 7-91 11-80 70-71 5-30 23-99 1-00 15-39 63-17 14-69 22-14 11-67 18-52 60-93 16-98 22-09 9-93 16-31 84-40 7-92 7-68 13-74 18-18 64-53 8-82 26-65 9-71 15-90 66-66 8-97 24-87 Deducting the sand, carbon, and carbon dioxide, as also the small proportions of alumina and ferric oxide found in the portion of the ash soluble in acid, the " pure ash" of the tobacco was calculated. The total nitrogen was determined by the absolute method of Dumas, and the nicotine by Mayer's solution, with the following results, expressed on 100 parts of tobacco dried at 100° C,:— No. 1, No. 2. No. 3. No. 4, No. 5. No. 6. Aver- age, Pure ash, .... Total nitrogen, . Nicotine, .... Nitrogen in forms other \ than nicotine, . / Percentage of total nitro-\ gen present as nicotine, / 8-94 3-18 3-32 2-61 18-2 9-29 2-63 3-59 2-01 23-6 12-34 3-72 5-28 2-81 24-5 14-84 5-76 7-09 4-54 21-3 13-39 5-33 6-20 4-26 20-1 11-06 5-26 8-86 3-73 28-9 11-64 4-32 5-72 3-33 22-8 The following table shows the average proportions of nitrogen 188 ASH OF TOBACCO. and ash, and the composition of the latter in tobacco from various sources : — Observer Number of specimens con- ) tributing to average, ) Nitrogen, per cent., . " Pure ash," per cent., Percentage composition qf ash— Si02, . CI, . . SOo, . . . P2O5, . . . K2O, NagO, . CaO, MgO, . NEW England. European VIEQINIA. KENTUCKY. (including Turkish). Irby&CabelL Peter. S.W.Johnson. E. Wolff. 6 30 12 13 4-32 ... 4-24 11-64 12-83 16-56 ... 1-72 2-73 0-84 10-29 2-81 3-74 9-36 4-92 5-49 4-21 6-58 4-30 3-30 4-99 3-56 3-21 35-58 37-57 34-96 18-01 2-78 2-10 1-99 4-29 37-60 35-31 34-48 43-51 10-72 9-35 8-21 11-46 Will and Fresenius (Ann. Chem. Pharm., 1. 387) have recorded the results of their analyses of the ash of a number of samples of Hungarian tobacco, and Schloesing {Jour. Pract Chem., Ixxxi. 148) the proportions of potash, lime, magnesia, sul- phates, and chlorides in the ash of tobacco grown on different soils. The proportion and composition of the ash of English tobacco has been investigated by A. Wingham (Jour. Sac. Chem. Ind.^ vi. 76, 400), of Indian and Burmese tobaccos by K.. Romanis {Chem. News, xlvi. 248), and of various kinds of tobacco grown in Japan by J. Takayama (Chem. Neios, 1. 301), and F e s c a and Imai (Jour. Soc. Chem. Ind., vii. 759). The combustibility of tobacco is profoundly affected by the pro- portion and nature of the universal constituents, especially the calcium and potassium, and the forms of combination in which these metals occur. The ash of the more combustible tobaccos is comparatively rich in potassium carbonate, showing the presence of a large proportion of organic salts of potassium in the original tobacco, while the ash of tobacco of inferior burning quality con- tains a larger proportion of sulphates or chlorides, and hence pro- portionately less alkaline carbonates. According to Schloesing and N e s s 1 e r tobacco burns best when it contains a considerable proportion of potassium malate, which is a natural constituent of the leaf; but the effect may be imitated, and a slow burning tobacco improved, by the addition of potassium acetate or other organic salt of potassium, while the combustibility may be dimin- ished by addition of sulphate of calcium or magnesium. According toE. R. Durrwell the whiteness of the ash of good tobacco is COMBUSTIBILITY OF TOBACCO. 189 due to the presence of a large proportion of alkaline salts, which swell up as the tobacco burns, and tear the fibres, thereby inducing complete combustion. Sulphates rather favour proper combination, while nitrates are prejudicial. Chlorides are regarded by most observers as objectionable, and hence should be absent from fer- tilisers intended for application to tobacco crops.^ A. Mayer (Land. Versachs-Stat., xxxyui. 127; Jour. Chem. Soc, Iviii. 1458) has investigated the influence of various sub- stances employed in 0'5 per cent, solution on the combustibility of ordinary filter-paper. Organic substances of the most difi'erent kinds were found favourable to combustion with flame and to diminish the power of glowing, while inorganic substances usually had the opposite effect.^ From his experiments with filter-paper, Mayer concludes that the more ash tobacco yields, and especially the more potassium carbonate (representing organic salts of potassium in the tobacco), the better the tobacco will burn ; while much calcium phosphate, sulphate, or chloride is held to be prejudicial. The alkalinity of the ash is a better measure of combustibility than the proportion of chlorine. Mayer gives the following figures obtained by the partial analysis of tobacco of difi'erent qualities from Sumatra. Tobacco. Chlorine. Total Potash. Alkalinity as K2CO3. ASH. Nitrogen. Good Sufficiently good Gight \ ash), , . / Sufficiently good, . Sufficiently good (grey \ ash), . . . / Bad, . . . . 1-5 0-5 0-7 1-2 8-8 5-9 5-8 6-6 7-9 4-6 4-9 6-8 5-5 4-1 0-5 20-5 20-8 22-5 17-7 18-5 2-7 8-2 2-0 8-8 2-6 1 G. Cantoni {Bied. Centr., 1879, p. 812) found that nitrates of the dlkali-metals had most effect as regarded vigour of growth of the tobacco, while alkaline chlorides and gypsum were prejudicial, the yield in weight being actually higher when no manure was applied than when ammonium sulphate or sodium chloride was added. The leaf was almost totally incombustible when the plant had been manured with gypsum, but that produced by manur- *aig with potassium sulphate was completely combustible. A. Mayer confirms the statement that chlorides are objectionable in tobacco manures, and states that their use increases the proportion of chlorine in the leaves from 0*21 to 0*52 per cent. ^ The salts found most favourable for glowing were the alkaline nitrates, sul- phates, and carbonates; alkaline organic salts; and potassium chloride. Sodium salts had less effect than potassium salts, and calcium and magnesium salts much less still. Paper treated with potassium salts, magnesium sulphate, or sodium carbonate gave a white ash. Chlorides were found rather to favour glowing. 190 COMPOSITION OF TOBACCO. According to J. M. van Bemmelin {Land. Versuchs-Stat., xxxvii. 409; Jour. Chem. Soc.^ Iviii. 1338), tobacco which burns badly either contains an excess of chlorine and sulphuric acid over the potash, or else the amount of potassium, compared with that of chlorine and sulphuric acid, is low, owing to the potash being partially replaced by soda. Leaves of the best quality contain little or no soda, not much chlorine or sulphuric acid, but a large proportion of organic salts of potassium, calcium, and magnesium. Too much fat or albumin in the tobacco neutralises the good effect of organic salts of potassium, and it is important that the albuminoids and carbohydrates should be sufficiently decomposed during the casing of the tobacco. In the ash the ratio of COgrCl + SOg is not less than 7 : 1, and the ratio of KiCl + SOg is not less than 2:1. According to Mayer, tobacco which burns badly can be made to burn well by steeping it for twenty-four hours in a 0'5 per cent, of potassium acetate or nitrate. Iti this way soluble organic matter and alkaline chlorides are extracted, while the salts favourable to glowing are taken up. By steeping in a 0"5 per cent, solution of calcium acetate, the most incombustible tobacco, which can other- wise only be used for snuff, can be made to burn well, and yield a perfectly white ash. The mode of existence of the nitrogen in tobacco has been investigated by Fesca and Imai (Jour. Soc. Chem. Ind., vii. 759), who have published the following among other interesting analytical data : ^ — Highest Lowest Average Percentage. Percentage. of S Samples. In air-dried tobacco— Sand, 1-91 1-02 1-48 Moisture, 12-21 8-39 10-46 In dry, sand-free tobacco— Pure ash, 14-64 10-68 12-82 Containing soluble CO3, . „ insoluble CO2, 0-57 0-34 0-44 419 3-05 3-54 „ K2O, .... 4-73 3-14 3-97 Crude fat, 14-44 10-34 12-12 1 Crude fibre, 15-50 13-17 14-10 Total nitrogen, 1-69 1-29 1-44 Amido-nitrogen, .... 0-67 0-32 0-48 Albuminoids 3-62 0-69 2-58 Nicotine, 4-09 2-63 3-16 Per \Q0 parts of total nitrogen — N as amido-compounds, 41-3 23-2 32-7 2f as albuminoids, .... 40-0 9-6 29-2 Nas nicotine, 48-6 29-7 38-1 ^ Fesca and Imai deduce the following conclusions from their researches : — The quantity of nicotine may be considered as bearing the same relation to tobacco as the percentage of alcohol does to spirituous liquors ; but as yet a COMBUSTIBILITY OF TOBACCO. 191 The aqueous infusion of tobacco contains a body which reduces F e h 1 i n g's solution. According to T. J. S a v e ry (CJiem. News, xlix. 123), the reducing body is almost entirely precipitated by basic lead acetate, the filtrate being without action on Fehling's solution. The body precipitated by lead acetate is probably caffetannic acid, and amounts, according to J. A 1 1 f i e 1 d (Pharm. Jour., [3], xiv. 541), to about 3 per cent, of the tobacco. But Attfield states that the solution after treatment with basic high percentage of nicotine has not been shown to be an indication of the good quality of tobacco. Nitric acid should not be found in well -fermented tobaccos. Ammonia determinations are frequently too high, as they include some amido-nitrogen. 0"1 per cent, or so of ammonia does not seem to lower the quality of the tobacco. The albuminoids in a tobacco afford no indication of quality unless the proportion of amides is simultaneously considered. The amido-nitrogen represents for the most part harmless, or, perhaps, even beneficial, nitrogenous compounds. It is possible that a further study of these bodies and their decompositions will reveal the presence of bodies exercising a direct influence on the quality of tobacco. Anyway, the conver- sion of albuminoids into amides is one of the most important results of the fermentation. Ordinary fat determinations, or rather extracts, are of no use in tobacco analysis. Carbohydrates should not be present in well-fermented tobacco, but a study of the changes they undergo would doubtless be of great value in connection with tobacco. Only considerable differences in the amount of the various constituents of tobacco can give any conclusive indication of the quality of a tobacco. Very bad tobaccos always contain much albuminoid matter, sulphuric acid, chlorine, and large quantities of mineral acids, with small proportions of amido-nitrogen, potash, &c. By the present methods of analysis it is easier to recognise a bad tobacco than one of good quality. Bases, particularly potash and lime, in medium quantity, are favourable to the good quality, and especially the combustibility, of tobacco. An excess of either of these bases over a liberal mean percentage is neither a sign of good quality nor combustibility, and only an exceptionally low percentage of either of them can be regarded with certainty as a bad sign. Very high magnesia is prejudicial to the combustibility. Mineral acids in large quantities indicate both bad combustibility and quality ; but only a very high proportion of an individual acid can be safely considered a decidedly bad indication. The com- bustibility is influenced to the greatest extent by the quantity of sulphuric acid present, and in a diminishing degree by the percentage of chlorine, phosphoric acid, and silica in the tobacco. The percentage of soluble carbonates appears to have no important influence on the quality and combustibility of tobacco ; the influence of the total quantity of carbonates in the ash is much greater, but even in this there is a maximum beyond which the percentage of carbonic anhydride in the ash cannot be regarded as indicating increase of combus- tibility. The relation of carbonates to the mineral acids is a much more important factor, a large preponderance of the former being a favourable sign. High basicity of ash is an excellent indication of good combustibility, especially when not due either entirely, or to a great extent, to magnesia or iron. 192 TOBACCO SMOKE. lead acetate still contains a sugar-like body, which he did not attempt to isolate, and which had little or no optical activity, but which yielded alcohol on fermentation with yeast, in amount corresponding to an average of 7 per cent, of sugar. Eastes and Ince (Pharm. Jour., [3], xvi. 682) found a small percentage (2 "5 to 5 "3) of a fermentable saccharoid matter, not removable by lead acetate, in the extract of tumbeki or Persian tobacco {Nicotiana Persica). The nicotine in this product ranges from 2 to nearly 6 per cent., and the ash from 22 to 28 per cent. H. Miiller (Bied. Gentr., 1886, p. 409 ; Jour. Chem. Soc, 1. 904) states that fermented tobacco contains, as a rule, little or no starch, and no sugar. The whole of the starch commonly disap- pears during the first few days of the drying. The sugar thus formed is often converted into water and carbon dioxide, and this change seems to be complete in leaves quickly dried. The last trace of sugar disappears when fermentation sets in, while any residual starch does not appear to be altered. From the analyses already quoted, it is evident that the propor- tion of nicotine in tobacco varies considerably.^ According to Schloesing (Chem. Gazette, v. 43) dried French tobacco con- tains from 5 to 8 per cent, of the alkaloid ; Virginia and Kentucky, 6 to 7 per cent. ; while Maryland and Havana tobaccos contain only about 2 per cent., and ordinary snuff about the same propor- tion. L. Eicciardi (Ber., xi. 1385) to some extent confirms these results, for he found the nicotine in twenty specimens of tobacco, grown in Italy under various conditions, to range from 5*99 per cent, in a Virginian variety to 1*62 in Havana tobacco. Tobacco Smoke varies in character according to the proportion of air admitted during combustion, oxidation being necessarily more perfect in the case of a cigar than when the tobacco is smoked in a pipe. In the latter case, a portion of the condensible products is deposited in the liquid state. Tobacco- smoke consists in part of permanent gases, the proportions of carbon dioxide and carbon mon- oxide in which have been determined by G. Krause. Vohl found sulphuretted hydrogen and hydrocyanic acid, and from 0*7 to 2*8 grammes of ammonia for 100 of tobacco smoked. Vohl and Eulenberg {Arch. Pharm., [2], cxlvi. 130) experimented on the smoke of strong tobacco, burnt both in pipes and in the form of cigars. The smoke was first aspirated through a solution of 1 According to Ad. Mayer a liberal amount of heat and liglit, together with sufficient moisture in a rich soil, will not only cause a luxurious develop- ment of tobacco plants, but give a large increase in the percentage of nicotine, while the other organic constituents of the plant are not much affected by climatic conditions. TOBACCO EXTRACT. 193 caustic potash, and then through dilute sulphuric acid. The alhali absorbed carbon dioxide, sulphuretted hydrogen, hydrocyanic, formic, acetic, propionic, butyric and valeric acids, phenol and creosote ; the presence of caproic, caprillic, and succinic acids could not be ascertained conclusively. The acid absorbed ammonia, pyridine, CgHg]^, and all the homologues of the series to viridine, CjgHjgN, inclusive. In addition to the above, carbon monoxide, methane, and several hydrocarbons of the acetylene series were detected. Pyridine was the chief base in the smoke from pipes, while coUidine was the prominent base in cigar-smoke. V o h 1 and Eulenberg conclude that the nicotine of tobacco is completely decomposed during the process of smoking, and that the intense action of tobacco-smoke on the nervous system is due to the presence of bases of the pyridine series. There is no doubt that some observers have mistaken these bases for nicotine ; but M e 1 s e n s' experiments {Dingl. Polyt. Jour., xlvii. 212) appear to be conclusive as to the presence of nicotine, which he isolated in a condition fit for analysis and to the amount of about 33 grammes for 4J kiligrammes of tobacco smoked, or about one- seventh of the quantity originally present.^ Tobacco Extract varies greatly in strength, and should always be assayed for the proportion of nicotine. A good extract is said to contain about 7 per cent, of the alkaloid. The following analyses by E. Geissler {Jour. Soc. Chem. Ind., viii. 425), of tobacco extract of 40° Baum^, indicate a wide difi'erence in its character, according as it is prepared from the leaves or midribs of the tobacco. Liquid. Mineral Matter. Containing K2CO3 Organic Matter. Containing Nicotine. Extract from leaves, . Extract from midribs, . 36-2 32-8 15-5 22-1 5-0 7-73 50-86 48-40 8-1 1-86 Snuff is manufactured from refuse-tobacco, such as stems, tobacco- smalls, and sweepings. These are moistened with water, subjected to a process of fermentation during six or eight weeks, then ground, mixed with alkaline salts as preservatives, and flavoured as desired. In the United Kingdom, nothing is allowed to be added to snuff ^ Melsens' conclusion has been endorsed by R. K i s s 1 i n g {Ding. Polyt. Jour., ccxliv. 64), who has collected and reviewed the observations of previous investigators. He considers V o h 1 ' s conclusion as to the non-existence of nicotine in tobacco-smoke to be due to that chemist having overlooked the fact that the alkaloid is decomposed by warm caustic potash, a reaction which, if a fact, has certainly not met with general recognition. VOL. III. PART II. N 194 SNUFF — PITURINE. but the chlorides, sulphates, and carbonates of potassium and sodium, and the carbonate of ammonium; and any snuff which contains a greater proportion of these salts than 26 per cent, on the dry snuff, including the salts natural to the tobacco, is liable to forfeiture and a penalty of £50. As the proportion of alkaline salts in tobacco-ash varies considerably, it is important that the manufacturer should know the amount present, in order that he may compound a snuff of uniform composition, and not exceed the legal limit. Of the salts allowed to be added to snuff, common salt and the carbonates of potassium and ammonium are those most commonly used. In addition, most snuff contains from 25 to 45 per cent, of water, and sometimes a considerable quantity of sand, the proportion, according to J. Clark {Jour. Soe. Ohem. Ind., iii. 554), averaging 5 per cent, on the dry snuff; but ranging from 0'5 to over 10 per cent., and in one case exceeding 30 per cent. A large number of gross and more or less apocryphal adulterants of snuff have been recorded. Among these the sulphides of arsenic, mercury and antimony, chromate of lead, bichromate of potassium, sulphates of copper and iron, alum, lamp-black, ivory-black, cream of tartar, red ochre, brick-dust, and various organic matters find a place. As snuff is neither a " drug " nor an article of food, it is not liable to examination under the Adulteration Acts, and the Excise systematically ignore sophistications which do not affect the revenue. Hence, authentic information respecting the present adulterations of snuff is very limited. Piturine. CigH^gNg. Piturine, the volatile alkaloid of pituri,^ was regarded by Petit as identical with nicotine, but its distinct individuality has been established by Liversidge {Pharm. Jour., [3], xi. 815). In its chemical characters and physiological effects piturine presents the closest resemblance to nicotine, but is distinguished from that base by its reaction with Palm's test. When gently warmed with hydrochloric acid of 1'12 specific gravity, nicotine turns violet, and on addition of a little strong nitric acid the colour changes to a deep orange. Piturine whW thus treated does not change colour at all, but when further heat is applied it turns yellow. Piturine is distinguished from c o n i n e by its aqueous solution not becoming turbid on heating, or by the addition of chlorine- water ; from aniline it is distinguished by its negative reaction with solution of bleaching powder ; and from picoline by being somewhat denser than water. From pyridine, piturine differs by ^ Pituri consists of the dried leaves of Duboisia Eopwoodii, a shrub growing in Australia. It contains from 1 to 2^ per cent, of the alkaloid. LOBELINE. 195 giving a precipitate with cupric sulphate insoluble in excess of the base. When piturine is treated in ethereal solution with iodine (com- pare sparteine) the liquid becomes brownish red and turbid, and after a short time deposits yellowish red needles, leaving a yellow mother-liquor. The crystals melt at about 110° C, and dissolve in alcohol with brownish red colour. This solution leaves indis- tinct needles and oily drops on evaporation ; if treated in the cold with caustic soda, an iodoform-like odour is evolved ; whereas the iodine-compound of nicotine is said to reproduce nicotine when similarly treated. Lobeline is the active principle of Lobelia inflata, or Indian tobacco, a plant which has received extensive application by un- authorised practitioners, and is also an official drug.^ Lobeline exists in lobelia in combination with a vegetable acid. In presence of certain other constituents of the plant the alkaloid is extremely unstable, being rapidly decomposed on heating an aqueous, or even an alcoholic, infusion of lobelia. In presence of acetic acid the base is more stable, and was obtained by J. W. and C. G. Lloyd {Pliarm. Jour., [3], xvii. 1038; xviii. 135) as a colourless, odourless, amorphous substance, permanent in the air, only slightly soluble in water, but readily soluble in alcohol, ether, chloroform, benzene, carbon disulphide, &c. In the pure state lobeline is not hygroscopic, and is but slowly changed on exposure to air. Lobeline turns red with sulphuric acid, yellow with nitric acid, and is precipitated by all the general alkaloidal reagents. The salts, which have not been obtained crystallised, are readily soluble in water, alcohol, and ether. They are described as most violent emetics, a single drop of a tolerably strong solution producing immediate emesis, without disagreeable after-symptoms. The dust is as irritating as veratrine to the nose and air-passages. ^ The entire dried herb constitutes the official drug, but the dried seeds of lobelia are also largely used. The root of Lobelia syphilitica was employed before L. inflata was known to medicine, but the root of the latter species does not appear to have been used. According to J. W. and C. G, Lloyd, all parts of lobelia contain the alkaloid, which, however, is most readily obtained from the seeds. The dust of the plant produces a painful sensation when inhaled. All parts of the herb and seed produce an acrid biting sensation on the tongue, and a sharp, tobacco-like impression on the throat and fauces. Lobelia contracts the pupil, and acts as an expectorant in small doses and an emetic in larger (10 to 20 grains). In poisonous quantities it acts like nicotine, and kills by paralysing the respiration. Several fatal cases of poisoning by lobelia are on record. 196 LOBELINE. Inflatin was obtained by J. W. and C. G. Lloyd in large colourless, odourless crystals, melting at 225°, insoluble in water or glycerin, but soluble in alcohol, ether, chloroform, benzene, carbon disulphide, and the oil of lobelia, &c. Inflatin is a neutral principle, and appears to have no therapeutic value. The lolelacrin of E n d e r s is considered by the Lloyds to be a mixture of inflatin, resin, lobeline, and the fixed oil which lobelia contains in the proportion of about 30 per cent. No liquid volatile alkaloid could be obtained by Messrs Lloyd from lobelia, by distilling the herb with water, either with or with- out the addition of caustic alkali, and they considered the supposed volatile base to have been probably a mixture of lobeline, inflatin, and volatile oil. On the other hand, Paschkis and Smita {Monatsh., xi. 131; Jour. Soc. Ghem. Ind., ix. 761) have obtained a volatile alkaloid from Lobelia injiata^ by extracting the leaves with water acidulated with acetic acid, rendering the concentrated solution alkaline, and agitating with ether. On distilling ofi" the solvent the alkaloid is obtained as a viscous oil, with an odour at once resembling that of honey and tobacco. It is purified by solution in dilute hydrochloric acid, and re-extracted by alkali and ether.^ After distilling off the ether the base is dried with caustic potash, and distilled in a current of hydrogen. On warming the alkaloid so obtained with a 10 per cent, solution of caustic potash, and gradually adding a 4 per cent, aqueous solution of potassium permanganate, benzoic acid is formed, and can be extracted by filtering off the precipitated oxide of manganese, and agitating the acidulated solution with ether. The sulphate of the above volatile alkaloid, if prepared from lobelia seeds, is obtained in yellow, very hygroscopic granules. When prepared from the leaves, it forms a yellowish white powder, less hygroscopic than the salt from the former source. According to D r e s e r, lobeline is the only medicinally active principle contained in Lobelia inflata. S. Nunez {Brit. Med. Jour.y 1889, 1059) considers it gre^y superior to the galenical preparations of lobelia, and recommends it in the treatment of spasmodical asthma and bronchitical dyspnoea. ^ Up to this point the process of Paschkis and Smita is substantially the same as that of the Lloyd Bros, for the preparation of the non-volatile alkaloid of lobelia. S i e b e r t, by the same process, has recently obtained, both from the herb and seeds of lobelia, a pale yellow alkaline syrup, the crystallised hydrochloride and chloroplatinate of which indicated the formula CigHgaNOg for the free alkaloid. SPARTEINE. 197 Sparteine. CigHggiS ^. This alkaloid is obtained by H o u d ^ and L a b o r d e (Pharm. Jour., [3], xvi. 543) by exhausting in a displacement-apparatus with proof-spirit the coarsely-powdered leaves and branches of broom (Spartium scoparium). The product is filtered, distilled under reduced pressure, the residue dissolved in tartaric acid, the liquid filtered to remove a greenish deposit containing chlorophyll and scoparin, CgiHggOj^Q, the filtrate rendered alkaline by potas- sium carbonate, and agitated several times with ether. The ethereal solution is shaken with tartaric acid, and the acid liquid separated and again rendered alkaline and extracted with ether, which on evaporation leaves the alkaloid ; the yield being about 0'3 per cent, of the plant used. Sparteine is a colourless, oily liquid, boiling at 287° at the ordi- nary pressure, or at 180° at 20 mm. It has a somewhat pungent, pyridine-like odour, a very bitter taste, and on exposure to air turns brown and thick. It is soluble in alcohol, ether, and chloroform, but insoluble in petroleum ether. Its solution in alcohol (24 per cent.) has a specific rotation of — 14°*6 for the sodium ray. Sparteine is a well-defined base, uniting with acids to form crystallisable salts, and having the constitution of a tertiary diamine. The sulphate forms large, transparent, very soluble rhombohedra,^ a solution of which gives with caustic alkalies and ammonia a white precipitate insoluble in excess. Cadmium iodide gives a white curdy precipitate, and sodium phosphomolybdate a white precipitate, dissolving on heating the liquid. Platinum chloride yields a yellow precipitate of BH2FtCl6-j-2aq., very insoluble in cold water and alcohol, but crystallising from hydro- chloric acid in rhombic prisms. Sparteine gives no coloration with concentrated mineral acids. "When oxidised with potassium permanganate, sparteine yields a ^ Administered in doses of 0"1 gramme, Sparteine sulphate is stated (G. See, Compt. Rend., ci. 1046 ; Year-Bodk Pharm., 1886, p. 283) to have a tonic action on the heart more prompt and lasting than that of digitalis or convallamarin, restoring the rhythm of the heart's action better than any known remedy, and resembling belladonna in accelerating the heart-beats in weak and atonic conditions of the heart. It does not appear to have any injurious action on the digestion, or on the nervous system generally. According to De Rymon, sparteine causes tremor, dilation of the pupils, inco-ordiuation of movements, and convulsions alternately tonic and clonic. Schroff found that a drop of sparteine introduced into a rabbit's mouth occasioned spasms of the muscles of the spine and limbs and paralysis of the latter, slowing of the respiration and heart, and death in six minutes. The effects of sparteine have been compared to those of conine, but they do not explain the value of broom as a diuretic medicine. 198 SPIGELINE. small quantity of a volatile (apparently fatty) acid, together with a non-volatile py ridine-carboxy lie acid, which on distillation with lime yields pyridine. Heated in sealed tubes with fuming hydriodic acid, sparteine yields methyl iodide and abase containing Cj^Hg^Ng. According to B e r n h e i m e r, on gradually adding 3 parts of iodine dissolved in ether to an ethereal solution of 1 part of sparteine a black precipitate is formed, which, when separated, washed with ether, and dissolved in boiling alcohol, crystallises on cooling in beautiful green needles containing CigHggNg-'-s- This body is insoluble in cold water or alcohol, but dissolves in either liquid when heated. It is insoluble in ether, permanent in the air, and yields free sparteine when heated with caustic alkali (compare "Piturine," page 195). Bromine acts strongly on sparteine at the ordinary temperature, even when largely diluted with ether, forming an undefined resinous mass. According to Grandval and V a 1 s e r, when a drop of ammo- nium sulphydrate is placed on a watch-glass, and a trace of spar- teine or one of its salts added to it, a permanent orange-red colora- tion is immediately produced. Spigeline is the active principle of Spigelia Marylandicay or "pink-root." As obtained by W. L. Dudley by distil- ling the root with milk of lime it was volatile, gave with iodine a brownish-red precipitate, and with Mayer's reagent a white crystalline precipitate soluble in alcohol and ether, and differing from most similar precipitates by being soluble in dilute acid. Spigeline is said by S t a b 1 e r to be bitter, precipitated by tannin, and soluble in water and alcohol, but not in ether (?). Pink-root is often used as a vermifuge, and possesses poisonous properties allied to those of gelsemium, depressing the action of the heart and of respiration, and in large doses causing loss of muscular power {Practitioner, July 1887; Amer. Chem. Jour., i. 138). It produces strabismus, dilatation of the pupils, and temporary loss of sight, with some drowsiness but not narcotism. A fluid extract of spigelia root is official in the U.S. Pharmacopoeia. ACONITE BASES.^ The different species of Aconitum contain alkaloids of a closely- allied character, but which differ from each other in their chemical 1 The subjects of this section are discussed at greater length and in more detail than their intrinsic importance seems to warrant, but it appears desir- ACONITE PLANTS. 199 composition and physiological activity. The characteristic aconite alkaloids are perhaps the most violent poisons known, but certain species of aconite contain simply harmless, bitter principles. All parts of the plant contain the poison, but the root is richest in alkaloid. If any portion of a poisonous aconite plant be chewed, it will be found to have a taste which may be at first bitterish sweet, but after a time becomes acrid and burning, causing a persistent sense of tingling and numbness of the gums and tongue, which effect lasts for some time and is highly characteristic. For medicinal use, the German and United States Pharmacopoeias admit only the tuberous root of Aconitum Napellus (W olf's-bane or Monk's-hoo d).^ The extract of aconite of the British Pharmacopoeia is prepared from the fresh leaves and flowering tops of A. Napellus (" gathered when about one-third of the flowers are expanded, from plants cultivated in Great Britain"), while the alkaloid (the description of which points to an impure product), the liniment and the tincture are directed to be prepared from the carefully-dried root of the same plant (" collected in winter or early spring before the leaves have appeared, from plants cultivated in Britain or imported in a dried state from Germany ").2 The French Codex authorises the use of the leaf and root of both A. Napellus and A. ferox possibly able to present the chemistry of the aconite bases in a more complete form than has been done since the publication of Alder Wright's classical researches ending in 1880. The author is indebted to Dr C. E. Alder Wright for perusal and correction of the article. ^ The root of A. Napellus is from 2 to 4 inches long, and of an irregu- lar conical form. It is much shrivelled longitudinally, and is more or less covered with the scars and bases of broken rootlets. Externally it is coffee- brown, but the transverse section is whitish, and exhibits a central cellular axis with about seven rays. The freshly-cut section rapidly acquires a reddish tint, a character which distinguishes aconite root from horse-radish, which it remotely resembles, and for which it has been fatally mistaken. The details of the structure of aconite root have been minutely described by Richards and Rogers {Pharm. Joicr., [3], xix. 912; Chemist aind Druggist, May 18, 1889), who point out certain differences between the German and British grown roots. The structure of A. heterophylluvi and Japanese aconite have been described minutely byWasowicz {Pharm. Jour., [3], x. 301; xi. 149). 2 Notwithstanding the importance, in the case of such a drug as aconite, of adhering strictly to the directions of the Pharmacopoeia, it is stated on the high authority of E. M. Holmes {Pharm. Jour., [3], xx. 900) that aconite-root as met with in commerce is generally of German or Japanese origin, the former being gathered indiscriminately from plants which may vary as widely in properties as A. heterophyllum (non-poisonous) and A. ferox (highly poisonous), and certainly do vary as much as A. Napellus (intensely poisonous) and A. paniculatum (non-poisonous). 200 ACONITE ROOTS. owing to the widely-spread, but apparently mistaken, impression that the alkaloid known as Morson's aconitine is prepared from the latter species (compare foot-note on page 216). The roots of aconite plants are not only the richest in total alkaloidal contents, but the alkaloids extracted from the root of A. Napellus were found by C. R. Alder Wright to contain a much larger proportion of the crystalline base aconitine than the alka- loids from the other parts of the plant (stem, leaves, and flowers). The various natural alkaloids of the aconites are, broadly speaking, characteristic of particular species of the plant. Thus aconitine is the peculiar alkaloid of A. Napellus, pseudaconitine of A.ferox, and japaconitine of^. Fischeri. It is highly probable that the traces of pseudaconine found by Alder Wright in the alkaloids from A. Napellus, and, conversely, the trace of aconitine detected in the bases from A. ferox, were due to unsuspected admixtures of other species of aconite in the parcels of roots which professedly came from one species only.-^ Thus, twenty-nine varieties of A. Napellus have been described, and some of these exhibited such differences that only an expert could distinguish them from nearly allied species. The true A. Napellus flowers in May, and appears to be peculiar in this respect ; it is impossible even for a skilled botanist to distinguish the plant by its leaves alone (E. M. Holmes, Pharm. Jour., [3], xii. 736).2 The roots of at least two species of Japanese aconite occur in the United States, viz., Aconitum Fischeri and A. uncinatum. The latter species has been described as poisonous ; but, according to V. Coblentz, the root, although it contains an alkaloid, is entirely devoid of the tingling and numbing taste of A. Napellus. The physiological experiments of Bartholow on the root of A. Fischeri indicate that this plant increases the number and force of the cardiac pulsations, instead of reducing the heart's action like A. Napellus. These and other results show that japaconitine and preparations of the Japanese root should by no means be substituted for A. Napellus for internal administration {Pharm. Jour., [3], xvi. 645). Besides the eminently poisonous alkaloids, aconitine, pseud- acofnitine and japaconitine, characteristic respectively of Aconitum Napellus, A. ferox, and A. Fischeri, other species of aconite ^Mandelin, by the examination oiA. Napellus alkaloids of various degrees of purity, was not able to detect pseudaconitine ; and J ii r g e n s also failed. * The root of Imperatoria Ostruthium, ormasterwort, has been met with as an adulterant of aconite. It resembles aconite tubers in shape, but has an aromatic odour and pungent taste, and the transverse section exhibits numerous oil cells arranged in several circles. ACONITE SPECIES. 201 contain alkaloids which appear in some cases to be highly poison- ous, and in other cases harmless, bitter tonics. Thus the alkaloid of Aconitum paniculatum (which was the official aconite of the London and Dublin Pharmacopoeias of 1836) is an inert, bitter principle, not improbably identical with the picraconitine isolated by T. B. Groves from a parcel of roots supposed to be those of A. Napellus. The root of A. heterophyllum contains a non- poisonous bitter alkaloid, called by its discoverer atisine ; and it is probable that similar bases occur in other species. Lyaconitine and myoctonine are physiologically active alkaloids isolated from A. lycoctonum. Some species of aconite appear to contain an unisolated base having distinct narcotic properties. The following table shows the chief sources of the aconite alkaloids and their derived bases. The root is the part of the plant referred to in each case : — Plant. Saponiflable Bases. Basic Products of Saponification. 1 Unsaponifiable Alkaloids. Aconitum Napellus. Monk's-hood. Wolfs- bane (blue flowers). Aconitum Ferox. Indian aconite. Nepaul aconite. Himalaya root. "Bikh" or "Bish." Aconitum Anthora (yellow- ish or white flowers). Aconitum Fischeri. Japanese aconite. Aconitum Undnatum. Aconitum Paniculatum. Aconitum Lycoctonum (yel- low flowers). Aconitum Heterophyllum (blue or dirty yellow flowers,with purple veins). Atis or Atees root. Aconitine. Amorphous base. Picraconitine (ex- ceptionally pre- sent). Pseudaconitine (very small quantity, if at all). Pseudaconitine. Amorphous base (?). Aconitine (in very small quantity, if at all). Pseudaconitine (?). Japaconitine. Amorphous base (?). Bitter inactive alka- loid. Picraconitine (?). Lyaconitine. Myoctonine. ? Aconine. ? Picraconine. Pseudaconine. Pseud aconine. Aconine. Pseudaconine. Japaconine. ? ? Picraconine (?). Lyaconine (Lycocto- nine). Lyaconine (Lycocto- nine). Amorphous unnamed base. Amorphous unnamed base. Amorphous unnamed base. Atisine. Constitution and Characters of the Aconite Bases. Much of the earlier work on the alkaloids of the aconites is of little value, owing to the readiness with which the bases 202 CONSTITUTION OF ACONITE BASES. undergo decomposition, and the consequent failure of the observers to obtain them in a pure state. The following table shows the leading properties of the better known of the aconite bases. Name. Synonyms and Sources. Formula. Appearance and Characters. Physiological Aconitine, Napaconitine. C33H48NO12 188 Crystallisable both in Intensely Crystallised free state and as poisonous. aconitine. salts. Alkaloid dex- From A. tro-rotatory. Salts Napellus. laevo-rotatory. Anhydro-aconi- Apoaconitine. C33H43NOU 186 Small coherent crys- As poisonous tine, tals ; crystalline salts. as aconitine. Aconine, . Saponification C26H41NOU 130 Amorphous ; forms Bitter ; moder- of aconitine. amorphous salts. Re- duces Fehling's solu- tion. ately poison- ous. Paeudaconltine, Acraconitine ; C36H49NO12 105 Base and salts crystal- Intensely napelline ; lise with difficulty. poisonous. feraconitine. Saponifiable. From A. Ferox. Pseudaconine, . Saponification C27H41NO9 100 Amorphous ; forms Bitter; slightly of pseudaconi- amorphous salts. poisonous. tine. Does not reduce Fehling's solution. Japaconitine, . Crystalline C66H88N2O21 184-186 Crystallisable ; forms Very poison- alkaloid of crystallisable salts. ous; closely Japanese Saponifiable. resembles aconite root. aconitine. Japaconine, . Saponification C26H41NO9 ... Amorphous ; forms Closely resem- of japaconi- amorphous salts. Re- bles aconine. tine. duces Fehling's solu- tion. Base crystallises with Picraconitine, . Doubtful ; per- C3iH46NOio above Bitter ; not haps the in- 100 difficulty: but salts poisonous. active alka- easily. Saponifiable. loid of A. paniculatum. Picraconlne, . Saponification of picraconi- tine. C24H4iN09 ... Amorphous. Bitter; not poisonous. Lyaconitine, , From root of A. lycoe- tonum. C27H34N2O6 112-114 Amorphous ; dextro- rotatory. Saponifi- able. Poisonous. Myoctonine, . With lyaconi- C40H56N2O12 144 Amorphous ; dextro- Bitter ; para- tine, in A. rotatory. Saponifi- lytic poison. lycoetonum. able. Lyaconine, Lycoctonine. Saponifica- C27H47N207 46 Crystallisable ; dextro- rotatory. Poisonous. Acolyctihe. . tion of lya- conitine. With lyaconine. ... White powder. Paralytic Atisine, . From root of C46H74N204 85 Forms crystalline poison. Bitter ; not A. hetero- haloid salts. poisonous. phyllum. It is not probable that either the foregoing list or that on last page includes all the distinct alkaloidal principles of the aconites. The so-called " amorphous alkaloids " have been very imperfectly SAPONIFICATION OF ACONITE BASES. 203 examined, owing to the difficulty of obtaining them in a condition of purity. Of those which have been partially examined, con- siderable uncertainty exists as to how far they are natural con- stituents of the original plant, and how far formed by polymerisa- tion or other changes during the process of extraction. T. and H. Smith obtained from the fresh juice of the roots of A. NapelltL» an alkaloid which appeared to be narcotine, and which they termed aconelline. The occurrence of this base has not been confirmed, but it is noteworthy that there is a relation in the constitution of narcotine and pseudaconitine ; for, while the former yields m e c o n i n, G^^kP^, or opianic acid, CioHj^Og, on saponification, the latter gives dimethyl-proto- catechuic acid. The following f ormulsB show the constitu- tion of the two last-named bodies. C O.CH3 ( O.CH3 p TT ) O.CH3 p TT J O.CH3 ^6^2^ CO.OH ^6^2 ^ CO.OH 1 CO.H (, H Opianic acid. Dimethyl-protocatechuic acid. The researches of C. R. Alder Wright have demonstrated that the crystallisable alkaloids of Aconitum Napellus^ A. ferox, and A. Fischeri (Japanese aconite) are alkyl salts or esters, either of benzoic acid itself or of a derivative of this acid. Thus, when heated with alkalies or mineral acids, or to some extent when heated with water alone, each of the crystalline bases undergoes saponification, with formation of benzoic acid, or a derivative thereof, together with a new amorphous base of far less physio- logical activity than the crystalline alkaloid from which it is derived.^ The following table shows the composition of the natural crystallisable alkaloids of the group, and the products of their saponification. The formulae of aconitine and aconine are those attributed to these bases by Dunstan and I n c e {Jour. Chem. Soc, lix. 271), and show Hg more in the mole- cule than the formulas of Alder Wright for the same alkaloids. 1 The statement made in the text requires qualification. Picraconitine is a saponifiable alkaloid, but is not poisonous. It forms readily crystal- lisable salts, but the free base has not been obtained crystallised. Atisine, again, is itself amorphous, but forms crystallisable haloid salts, and i& not known to be saponifiable. Lyaconitine and myoctonine have not been obtained crystallised, but are saponifiable and yield crystallisable salts. 204 SAPONIFICATION OF ACONITE BASES. CRTSTATiTJNB BASE. Products op Hydrolysis. Amorphous Base. Acid. Acoaitine, C33H45NO12 Picrdconitine, C31H40NO10 Japaconitine, C66H88N2O21 Pseudaconitine, C36H49NO12 Aconine, C26H41NO11 Picraconine, C24H:4iN09 Japaconine, 2C26H41NO10 Pseudaconine, C27H41NO9 Benzoic acid, C7H6O2 Benzoic acid, C7H6O2 Benzoic acid, 2C7H6O2 Veratric acid (dimethyl- protocatechuic acid), C9H10O4 Lyaconitine, the amorphous alkaloid of A. lycoctonum^ also yields an acid and one or more bases on saponification (of which one, lycoctonine, readily crystallises), but it is doubtful if the reaction can be expressed by any simple formula (see page 223). The amorphous alkaloid myoctonine, from the same source, yields benzoic acid on saponification, together with the crystalline base lycoctonine, and other products. The saponification of the crystalline aconite bases occurs with a near approach to quantitative accuracy, at least so far as the production of the acid products is concerned ; the basic product usually undergoing some further change with formation of a resinous substance. The reaction is best effected by boiling the alkaloid with alcoholic caustic soda for some time, under a reflux condenser. If the product be then acidulated with hydro- chloric acid, and agitated with ether, the acid products of the saponification are dissolved. On separating the ethereal solution, and shaking it with soda, the benzoic and veratric acids are dissolved, while resinous matter remains in the ether. On again acidulating the separated alkaline liquid the acids are liberated, and may be dissolved out by agitation with ether. After allowing the washed ethereal solution to evaporate spontaneously, and drying the residue over sulphuric acid, the acids may be weighed; or, where yOnly one is present, the amount may be ascertained by titrating the ethereal solution with standard alkali and phenol- phthalein. A method adapted for the assay of very small quantities of the aconite bases, and based on this principle, is described on page 234. After weighing, the melting-point of the acid may be ascertained. Benzoic acid melts at 121° C, and may be separated from veratric acid (page 218) by prolonged distillation with water, when only the former body passes over. The distillate may be rendered alkaline, concentrated to a small bulk, acidulated, and the ANHYDRO ACONITE BASES. 205 benzoic acid extracted with ether, and recovered by evaporation of the solution. The veratric acid may be similarly recovered from the liquid left in the retort. The following table shows the proportions of carbon and hydrogen contained in the crystallisable aconite bases, together with the percentage of gold contained in their aurochlorides (dried at 100°), and the proportion of acid yielded on saponi- fication : — Alkaloid. Formula. Carbon. Hydrogen. Gold in Auro- chloride. Add by Saponifi- cation. 1 NaHO required for Saponifi- cation. Aconitine, . Pseudaconitine, . Picraconitine, Japaconitine, C33H46NO12 C36H49NO12 C31H46NO10 C66H88N2021 61-20 62-88 62-95 63-67 6-95 7-13 7-61 7-07 19-96 19-10 21-07 20-89 18-92 26-49 20-60 19-60 6-20 5-82 6-77 6-43 When the hydrolysis of the natural aconite bases is effected by heating with concentrated mineral acids, or even by water alone under high pressure, the saponification is preceded or accompanied by the removal of the elements of water and a formation of the so-called " apo-bases," preferably called anhydro-bases. The follow- ing table shows the relation of the apo- or anhydro-bases to their parent alkaloids, and exhibits the constitutional formulse of the former : — Alkaloid. Anhydro-base. Aconitine. {OH OH O.CO.CeHg Aconine. OH ^25237^^7^ OH OH Anhydro-aconitine. C26H37NO. ■( OH O.CO.C^H, Anhydro-aconine. CgsHa^NOy^ OH (oh C27H37NO6 Pseudaconitine. OH OH OH O.CO.C6H3(OCH3)2 C27H37NO5 Anhydro-pseudaconitine. OH O.CO.C6H3(OCH3)^ 206 ACETYL AND BENZOYL DERIVATIVES. Pseudaconine. Anhydro-pseudaconine. (oh (0 €27^37^0, ^ ^g C^^s,^'0, ^ OH (oh ^^^ The anhydro-bases are best prepared by heating the parent alkaloids to 100° for six to ten hours with a saturated aqueous solution of tartaric acid. On rendering the liquid alkaline with sodium bicarbonate, and shaking with ether, the anhydro-base is dissolved, and may be obtained in crystals on evaporation of the ethereal solution. In their physiological effects, the anhydro-bases resemble the alkaloids from which they are derived. Thus " apo-aconitine," or anhydro-aconitine, is extremely poisonous, while anhydro-aconine is nearly inactive. Japaconitine, the natural alkaloid of Japanese aconite root, undergoes no further change when heated with tartaric acid, for it has the constitution of a sesquianhydro-derivative : — C,eH3,N0,i O.CO.C,H, r C,,H3,N0j0.C0.CeH, The hydrogen of the OH-groups of the anhydro-bases is capable of replacement by organic acid-radicals. Thus when pseudaconitine is heated to 100° for some hours with a large excess of glacial acetic acid, it loses the elements of water, but the anhydro-base formed is then further acted on with formation of acetyl-anhydro- pseudaconitine, which is a base crystallising (like the parent alkaloid and its anhydro-base) with IHgO, forming a crys- talline nitrate and gold salt, and yielding acetic and dimethyl- protocatechuic acids on saponification with alkalies. The same product is obtained if acetic anhydride be used in place of acetic acid ; while, if benzoic anhydride be substituted the corresponding b e n.z o y 1-d erivative is produced. When aconitine is heated withlbenzoic anhydride it yields, in a similar manner, benzoyl- anhydroaconitine, a product which is apparently identical with that obtained by the action of benzoic anhydride on aconine. /OH I r)XT Aconitine, .... CagHgyNOyK ^tt (oBz ACONITINE. 207 Anhydroaconitine, , . , CofiH^y^OyK OH ( OEz Benzoyl-anhydroaconitine or Di- \ p tt -s^r) J ^tj benzoyl-anhydroaconine, . j ^26^37^ ^7 i ^^^ Japaconitine is converted by benzoic anhydride into a derivative containing four benzoyl-groups, CgeHggNO^^O.Bz)^. The fact may be utilised for distinguishing the alkaloid of Japanese aconite from true aconitine as described on page 221. Aconitine. IN'apaconitine. Benzoyl-aconine. C33H45NO12; or C2eH3,NO,(OH)3.0.CO.CeH5. Aconitine is the crystalline alkaloid of the root of Aconitum Napellus, Monk's-hood or Wolf's-bane (French, Coque- luchon ; German, Eisenhut, Sturmhut). It exists in combination with aconitic acid, CgHgOg (Vol. I. p. 452). Aconitine is extremely difficult to obtain in a state of purity, owing to the facility with which it is converted into an a n h y d r 0- b a s e, and suffers hydrolysis with formation of the amorphous base aconine, if a mineral acid be employed in its extraction.^ Alder Wright found that the whole of the alkaloid could be extracted by alcohol from Japanese aconite root without the addition of any acid ; and the same appears to be true of the root of other species of aconite. Thus C. F. Bender (Pharm. CentralU.^ xxvi. ^ One of the best methods of preparing aconitine from aconite root is that of Duquesnel {Jour. Pharm. et Chimie, [4], xiv. 94), who exhausts the material in the cold with rectified spirit to which has been added a small amount of tartaric acid. The alcoholic solution is distilled out of contact with the air at a temperature not exceeding 60° C, and the residue diluted with its own measure of water, and filtered from the precipitated resinous and fatty matters. The acid liquid is next agitated with ether or petroleum spirit to remove colouring-matters, and then rendered alkaline with sodium bicarbonate, which precipitates the aconitine and a portion of the amorphous bases, a large portion of the latter remaining in solution. The precipitated alkaloid is extracted by agitation with ether, which, on evaporation or precipitation by petroleum spirit, deposits the base in colourless rhombic tables, which some- times appear hexagonal in consequence of the modification of the acute angles. The aconitine thus obtained is contaminated by an admixture of amorphous alkaloid, which clings to it with great obstinacy, and cannot be removed simply by crystallisation ; but by converting the base into the hydrochloride, or preferably the hydrobromide, recrystallising the salt, and liberating the alkaloid by sodium carbonate, a product is obtained which, when recrystal- lised from ether, is very pure. 208 PREPARATION OF ACONITINE. 433) has applied extraction by unacidulated alcohol to the pre- paration of pure aconitine, and the B.P. process is based on the same principle. R. Wright {Pharm. Jour.^ [3], xx. 375) found that chloroform alone did not extract nearly all the alkaloid from aconite root. By first moistening the root with ammonia, drying it carefully, and then percolating with chloroform, T. B. Groves obtained a much better yield than with chloroform alone. John Williams employed amylic alcohol for extracting aconitine.^ For the final purification of aconitine, D u n s t a n and I n c e {Jour. Ghem. Soc, lix. 271) employed solution of the base in cold dilute hydrochloric acid, and addition of auric chloride in quantity sufficient to precipitate one-fifth of the alkaloid present. The amorphous alkaloid was wholly precipitated, and from the filtrate the pure aconitine was precipitated by sodium carbonate, and when crystallised from ether-alcohol was obtained in large, flat, rhombic prisms with truncated ends, which appeared as hexagonal plates under the microscope.^ D u n s t a n and I n c e {Jour. Ghem. Soc, lix. 271) attribute to the pure aconitine obtained by the above method the composition CggH^gNOig, which differs by Hg from the formula of Alder Wright; but the method of combustion on which both formulae are based is scarcely delicate enough to decide between the two, and as hydrogen-determinations have ^ The following is an outline of the method of preparing crystallised aconi- tine ultimately practised by J. Williams (and posthumously published by Richards and Rogers, Chemist and Druggist, Feb. 7, 1891), being an improvement on the process previously described by him (Pharm. Jour. , [3], xviii. 238) : — The aconite root is coarsely ground and macerated in the cold for three or four days with amylic alcohol, which solvent removes both the free base and its salts. The solution is shaken with successive small quantities of water slightly acidulated with sulphuric acid (^ fluid ounce to the gallon). The last washings should retain a distinct acid reaction, and the liquor should be examined to insure complete extraction of the alkaloid. The acid liquid is then shaken several times with washed ether, to remove amylic alcohol and colouring-matter, and then gently warmed to dissipate the remaining ether. "When quite cold the solution is treated with sodium carbonate, and the pre- cipitated alkaloid filtered off, pressed, and dried by exposure to air. When dry, it is boiled for some time with ether (previously washed with water and dried by potassium carbonate), and the solution filtered hot into a basin, when nearly^he whole of the alkaloid will crystallise out. The ring of un- crystallisable gummy matter which forms at the edge of the dish can be dissolved by a little cold ether, in which the crystals are only sparingly soluble. 2 The microscopic appearance of aconitine is regarded by Richards and Rogers as the best and most characteristic test of the alkaloid {Chemist and Druggist, May 18 1889). Crystallisation is best effected from somewhat dilute alcohol. CHARACTERS OF ACONITINE. 209 notoriously a tendency to be in excess of the truth, the H^g formula is quite as probable as the other. Aconitine is only very sparingly soluble in cold water, requiring 726 parts at the ordinary temperature, according to Jiirgens, and nearly ten times this proportion, according to J C. U m n e y In hot water it dissolves more freely, and is soluble in 24 parts of rectified spirit, readily in chloroform and benzene, and moderately in ether ; but is almost insoluble in carbon disulphide and petro- leum spirit, and is precipitated by the latter from its solution in benzene or ether. It is not extracted from its acidulated solutions by any ot these solvents. Aconitine has a slightly bitter taste, the intensity of which is said to be inversely as its purity. It is extremely poisonous. Solutions, sufficiently dilute to be safely employed, cause a characteristic tingling and numbness of the lips, tongue, and pharynx. ^ Pure aconitine is stated by Dunstan and I n c e to melt at ISe^'S C. (corrected), but Duquesnel gives 140°, Alder Wright 183°-184°, and Jiirgens 179°. The material of the earlier observers was probably sensibly impure, but the want of con- cordance may be due in part to the mode of heating the alkaloid. Thus when slowly heated aconitine melts at a lower temperature than when heated quickly. Dunstan and I n c e recommend the use of a bath of paraffin, long enough to entirely immerse the stem of the thermometer. The bath is heated to about 150°, before the thermometer with the thin glass tube containing the alkaloid is immersed, and is kept well stirred throughout the operation.2 Aconitine in the free state is dextro-rotatory, a 3 per cent, solution in alcohol having a specific rotatory power of -|-ll°'l for the sodium ray. On the other hand, the salts are Isevo-rotatory, the hydrochloride in aqueous solution showing S^ = — 35°'9. Similarly ^ Aconitine is probably the most violent poison known, t^ grain is the ordinary medicinal dose, and ^V grain a fatal dose for an adult. In working with aconitine, great care must be taken to avoid the action of the base and its salts, especially in the solid state. A minute fragment of the dust, too small to be seen, if accidentally blown into the eye, sets up the most painful irrita- tion and lachrymation, lasting some hours ; while, if inhaled, a like amount will produce great bronchial irritation or profuse sneezing, and considerable catarrh or sore throat (C. R. A 1 d e r W r i g h t). ^ Alder Wright states that aconitine melts in a capillary tube at 183°- 184° (corrected). The final complete melting is preceded by a slight fritting beginning a few degrees below the melting-point, which is lowered by the presence of amorphous bases. With pure aconitine very slight darkening occurs, but it is more marked with impure material. VOL. III. PART H. 210 SALTS OF ACONITINE. the crystalline hydrobromide, CggH^gNO^gHBr -|- 2^ aq., gives So= — 30°'5 in 2 per cent, aqueous solution. Salts of Aconitine. Aconitine has well-marked basic properties, ana forms a series of crystallisable salts. Caustic alkalies, fixed alkaline carbonates and ammonia (but not am.moniuni carbonate or fixed alkaline bicarbonates), throw down the free base from the solutions ol its salts as a white flocculent precipitate, practically insoluble in excess of the reagent. The salts of aconitine with the mineral acids are neutral to methyl-orange and rosolic acid, but may be titrated with stan- dard caustic alkali and phenolphthalein, just as if the acid existed in a free state. Aconitine Aconitate exists ready-formed in aconite root. It is gummy in appearance, and crystallises with difficulty. It dissolves in water, alcohol, amylic alcohol, and chloroform; and is partially precipitated from its solution in the last menstruum by the addition of ether. Aconitine Nitrate is readily obtained by dissolving aconitine in dilute nitric acid, and then adding gradually an excess of moder- ately strong nitric acid, when the salt separates in a bulky form, rendering the mixture semi-solid.^ When pressed to separate the mother-liquor, and recrystallised from water, it forms rosettes or fine rhombic and short prismatic crystals, which are colourless and transparent, but slightly efflorescent. The aconitine nitrate thus prepared has a very anomalous com- position, containing as it does £2(11^03)3.^ The neutral nitrate, BHNO3, is obtainable as an amorphous residue by evaporating a solution in an equivalent quantity of dilute nitric acid. Aconitine nitrate is only sparingly soluble in cold water; but * According to J. "Williams {Year-BooTc Pharm.^ 1886, 433), when aconitine is recovered from the nitrate prepared in this way it crystallises in a different manner from the original alkaloid. This experience is confirmed by Richards and Rogers {Chemist arirfZ'rwf/pfts^, May 18, 1889, andFeb. 14, 1891), who attribute a greatly increased physiological activity and slightly reduced melting-point to tlie alkaloid thus recovered. This interesting result may possibly be due to the partial or complete conversion of the original alkaloid into anhydroaconitine (page 213) by the action of the strong acid employed. If this suggestion be well founded, the anliydroaconitine could be separated as indicated on page 214. 2 A. Jiirgens found crystallised aconitine nitrate, dried at 100°, by titration with caustic alkali and phenolphthalein, to contain a proportion of nitric acid corresponding to the sesqui-nitrate (1271 per cent.), while one- third of this was indicated by rosolic acid (Inaugural Dissertation, Dorpat 1886). ACONITINE AUROCHLOKIDE. 211 it dissolves easily in water saturated with carbonic acid, and gradually crystallises as the gas escapes from the liquid. Aconitine Sulphate is obtained by evaporation of its solution at a gentle heat as a vitreous non-deliquescent mass, which appears under the microscope as a confused mass of crystals. Aconitine Hydrohr amide, C^^^^O^^^^t, crystallises readily in monoclinic tables containing, according to Jiirgens, 2J aqua. Aconitine Hydrochloride^ CggH^gNOig.HCl, is obtained by slow evaporation of its solution in large rhombic crystals which, accord- ing to J ii r g e n s, contain 3 aqua. Aconitine Aurochloride, CggH^gNOjgjHAuCl^, is thrown down as a yellow amorphous precipitate on adding auric chloride to a solution of aconitine hydrochloride, or to the salt of the alkaloid to which sodium chloride or hydrochloric acid has been added. The precipitate is formed even in very dilute solutions, and is only very sparingly soluble in dilute hydrochloric acid. It dissolves readily in absolute alcohol, methyl alcohol, chloroform, and acetone, but less readily in ether and dilute alcohol. The com- pound can be crystallised from alcohol, the deposition being facilitated by the cautious addition of water. When pure, aconitine aurochloride melts at 135°'5 (corrected), but a very small propor- tion of impurity tends to reduce the melting-point to 130°, or less. From a solution of impure aconitine hydrochloride, the impurities are thrown down first, on gradual addition of auric chloride. Duns tan and Ince recommend the preparation of the auro- chloride and the determination of its melting-point as a reliable means of identifying aconitine, especially as the pure alkaloid can be readily recovered in a crystalline state from the compound. The only successful method of effecting this, out of a large number tried, was to grind the aurochloride to a fine powder with water, and add sulphuretted hydrogen water, drop by drop, till the gold is wholly precipitated as sulphide. An excess of the reagent should be avoided. The liquid is then filtered, a current of air passed to remove any slight excess of sulphuretted hydrogen, sodium bicar- bonate added in slight excess, and the liberated alkaloid extracted by agitation with ether. On mixing alcoholic solutions of free aconitine and auric chloride, and gradually adding water, aconitine gold chloride, BAuClg, is precipitated. When recrystallised from alcohol the compound melts at 129°. Chemical Reactions of Aconitine. A solution of iodine in iodide of potassium produces a reddish brown or yellowish amorphous precipitate, even in very dilute (1 : 20,000) acidulated solutions of aconitine. Mayer's leagent 212 REACTIONS OF ACONITINE. precipitates aconitine solutions, if not more dilute than 1 in 10,000, and may be used foi the determination of the alkaloid. Phos- phomolybdic acid also precipitates moderately dilute solutions (1 : 5000), and if the aconitine be pure the precipitate dissolves in ammonia without blue coloration. Phosphotungstic acid behaves similarly. Picric acid precipitates solutions which are not too dilute ; but mercuric chloride gives no reaction with aconitine solutions much below 1 per cent, in strength ; while platinic chlo- ride, and potassium chromate, iodide, ferrocyanide and ferricyanide fail to precipitate aconitine solutions unless very concentrated. According to A. Jiirgens (Arch. Phar7n.,[3], xxiv. 127, 172) aconitine can be identified under the microscope by dissolving a minute quantity in water acidulated with acetic acid, and adding a particle of potassium iodide. On allowing the solution to evaporate, characteristic crystals of aconitine hydriodide appear, and remain after adding water to dissolve the crystals of potassium iodide simultaneously formed. An alcoholic solution of aconitine reduces silver nitrate, but no reduction is produced by the salts of aconitine. A mixture of solutions of potassium ferricyanide and ferric chloride is turned blue by aconitine. Aconitine, when pure, gives no marked colour-reactions, but as extracted from the tincture and other pharmaceutical preparations, by adding an alkali and agitating with ether, it yields certain colour-reactions which are serviceable as supplementary tests for the aconitine-alkaloids generally (see page 242). The most characteristic property of pure aconitine is its physiological action, which may be supplemented by the reactions with auric chloride, potassium iodide, and the formation of benzoic acid and aconine on saponification. As tests for the purity of aconitine. Alder Wright recom- mends the observation of the melting-point, supplemented by the following: — The alkaloid is dissolved in a few drops of dilute acid, pure ether adjied, and then excess of sodium carbonate solution; the whole being well agitated in a stoppered bottle. The ethereal solution is then separated and allowed to evaporate spontaneously. When only a small volume is left, this is poured away from the deposited crystals, and allowed to evaporate com- pletely. If the aconitine were tolerably pure, the last drops of the ethereal solution will leave a crystalline residue ; but if more than minute quantities of amorphous bases be present, these will accumulate in the ethereal mother-liquor, the last portions will leave a varnish or gummy residue on evaporation. When strictly imre, aconitine dissolves without colour in sulphuric DECOMPOSITION OF ACONITINE. 213 acid ; and on adding a few drops of concentrated syrup no red coloration should be produced, even after standing some time. When heated for some hours to 100° C. with alcohol and caustic soda, aconitine should yield close on 20 per cent, of benzoic acid, determined as on page 234. The resulting acid should melt at 120°, and should not yield any protocatechuic acid on fusion at 250° with caustic potash. This and the other reactions described on page 219 distinguish aconitine from pseudaconitine. From japaconitine, aconitine can be distinguished by its crystalline form, by careful determination of the carbon and hydrogen (compare page 204), and by its behaviour with acetic and benzoic anhydrides. In all other characters the two alkaloids closely correspond. Aconitine is quite unchanged when heated to 100° in a vacuum, and but very slightly altered at 120°. When kept for an hour at its melting-point it loses about 10 per cent, of its weight, and the residue consists wholly of a c o n i n e, CggH^-^NOj^. When aconitine is heated with water to 100° for many hours in a sealed tube, it is hydrolysed with formation of aconine and benzoic acid :— C35H45NO12 + HgO = Cg.H.iNOn + C^HgOg. The reaction is apt to be incomplete, only 85 per cent, of the base being hydrolysed by heating with water in sealed tube to 1 40° C. for twenty-four hours. By mere boiling with water under a reflux condenser for a few hours, the alkaloid is practically un- changed. If ammonia be added to the water, a small but appre- ciable decomposition ensues. Solutions of potassium and sodium carbonates act more powerfully, some hydrolysis occurring even in the cold after prolonged standing, while on boiling nearly complete saponification into aconine and benzoate ensues. Caustic alkalies rapidly effect the same decomposition, especially in alcoholic solution. When aconitine is heated with a dilute mineral acid (especially hydrochloric acid), the first action consists in the removal of the elements of water with formation of apo- or anhydro- aconitine, CggH^gNOji. But this dehydration is rapidly succeeded by hydrolysis, and formation of aconine and ben- zoic acid, just as when alkalies are employed. On the other hand, the weaker organic acids do not eff'ect this hydrolysis, or do so but very imperfectly. Thus aconitine yields no appreciable quantity of benzoic acid when heated to 100° C. for ten hours, with a saturated aqueous solution of tartaric acid ; but this treat- ment effects the complete conversion of the alkaloid into apo- or anhydro-aconitine. Anhydro-aconitine, C33H43NO11, is best obtained by heating aconitine to 100° with a saturated solution of tartaric acid. On evaporating the ethereal solution of the base it is obtained in 214 ACONINE. small colourless crystals, which cohere and stick to the sides of the glass vessel in a characteristic manner. It melts at 186°*5, i.e.y 2° lower than aconitine, and in other respects (including its poisonous properties) closely resembles the parent alkaloid. An- hydro-aconitine forms crystalline salts. The aurocliloride forms an amorphous precipitate which dissolves in absolute alcohol. If the solution be evaporated in vacuo over calcium chloride, the compound BHAuCl^ is deposited in crystals melting at 141°; but if the alcoholic solution be precipitated by gradual addition of water, the crystals deposited melt at 129°, and contain CggH^gNOjpHAuCl^+HgO. When this is recrystallised from dilute alcohol it is converted into aconitine aurochloride, C33H45NOi2,HAuCl4, melting at 135°"5. Anliydroaconitine gold chloride, BAuClg, is obtained by mixing alcoholic or ethereal solutions of the base and auric chloride. It melts at 147°'5, and shows no tendency to pass into the aconitine salt (D u n s t a n and Ince, Jour. Ghem. Soc, lix. 284). Commercial aconitine is liable to contain the anhydro-base, which may be removed by converting the alkaloid into the hydrobromide, and crystallising the salt from water, when the salt of anhydro-aconitine remains in the mother-liquor. AcoNiNE, CggH^^NOij, probably occurs ready-formed in aconite root, and certainly in other parts of the plant. It may be obtained pure by boiling aconitine with alcoholic potash or soda for some hours, distilling off the alcohol, acidulating the liquid with hydro- chloric acid, and removing the benzoic acid by agitation with ether. On rendering the solution alkaline, and shaking with chloroform (aconine being reputedly insoluble in ether), the base is taken up.^ On adding light petroleum gradually to the chloroformic solution the aconine is precipitated. The first portions are impure, but the last fraction is nearly free from colour, though still resinous and friable when dry. Aconine melts at 130°, is soluble in alcohol and chloroform, and somewhat soluble in water, but is insoluble in anhydrous ether, benzene, and petroleum spirit. Both the free base and its salts resist all attempts to crystallise them. The solutions yield amorphous precipitates with the usual alkaloidal reagents. The aurocliloride, BHAuCl^, is a pale yellow amorphous precipitate, which is deposited in oleo-resinous films on evaporating its solu- tion in alcohol (D u n s t a n and Ince, Jour. Chem. Soc, lix. 286). * The author's experience is that if the alkahne liquid be shaken with ether, the greater part of the basic saponification-product (aconine) is extracted, but that a small additional amount of base can be recovered by subsequent agita- tion with chloroform. AMOllPHODS BASES. 215 For the isolation of aconine from the mixed alkaloids of A. Napellus, the bases are dissolved in dilute acid, excess of potassium bicarbonate added, and the precipitated aconitine filtered off or extracted by ether. The filtrate is slightly acidulated and precipitated by potassio- iodide of mercury, the precipitate sepa- rated, suspended in alcohol, and decomposed by sulphuretted hydrogen. On evaporating the filtered liquid, the aconine is obtained as a resin which can be purified by treatment with ether, to remove colouring-matter and other alkaloids, solution in benzene, and precipitation by petroleum spirit. But the product is always amorphous, and yields amorphous salts. Aconine is very bitter (far more so than aconitine), but does not produce tingling of the gums, and has very little physiological activity {-^^q that of aconitine). It is also distinguished from aconitine by its uncrystallisable character, its readier solubility in water and insolubility in ether, and by not yielding benzoic acid when boiled with alcoholic potash or soda. It reduces gold and silver salts at the ordinary temperature and Fehling's solution on heating. It gives a blue coloration when added to mixed solutions of ferric chloride and potassium ferricyanide. Anlujdro-aconine, C^^^^^O-^q, is obtained by heating aconine hydrochloride to 1 40° The base and salts are amorphous. It is bitter and very feebly poisonous. Amorphous Saponifiable Bases of Aconitum Napellus. In addition to aconitine, the active and crystalline alkaloid of A. Napellus, and picraconitine, which appears to be occasionally present, indications of the presence of another saponifiable alkaloid have been met with by several observers. Thus Alder Wright and Luff {Jour. Cliem. Soc, xxxiii. 318) found that the mother-lic^uors, from which as much crystalline aconitine as possible had been separated, contained an amorphous base showing = 66*39, and H = 7"94 per cent., and which gave about 14 jDer cent, of benzoic acid on saponification. Wright (private communication to the author) states that it is impossible to form any idea of the pro- portion of the amorphous saponifiable base present, and does not regard his product as a single alkaloid, but believes it still retained aconitine, which was prevented from crystallising by the amorphous bases present. He thinks it probable that the benzoic acid pro- duced on saponification was mainly derived from amorphous saponifiable bases, which may possibly have been in part pre- existent in the plant, but probably were chiefly alteration-products of aconitine, just as the amorphous base quinicine results from the alteration of quinine. A. Jiirgens (Inaugural Dissertation, Dorpat, 1885) has also isolated an amorphous saponifiable base from the root of 216 AMORPHOUS ACONITE BASES. A. NapelluSf and found it to contain C = 67*74, H = 8'40 per cent., and to yield an unstated proportion of benzoic acid and a base allied to aconine on saponification.^ BHCl, BHBr, BHI, BgHgSO^, BHNO3 and BHA were amorphous, but the very small quantity of material at disposal prevented any complete examina- tion of the alkaloid being made. It is probable that the amorphous saponifiable base of A. Napellus bears the same relation to aconi- tine that quinicine bears to quinine, and is a polymeiide of the crystallisable alkaloid. Hence the name aconicine would appear convenient and appropriate. J. C. Umney states that the amorphous saponifiable base of A. Napellm produced no ill effects on him when taken in ] grain doses. PseudaCOnitine. Feraconitine. Yeratroyl-pseudaconine. C36H49NO12; or C2jH3,NO,(OH)3.0.CO.C6H3(OCH3)2 Pseudaconitine is the characteristic crystalline alkaloid of Aconitum ferox, a native of the Himalayas, and is stated to be also present in A, anthora, and other species ; also, according to Alder Wright, in small quantity in A. napellus.^ ^ The remarks made byMrJohn C. Umney before the British Pharma- ceutical Conference of 1891 (Pharm. Jour., [3], xxii. 223, 447; Chemist and Druggist, xxxix. 293 ; British and Colonial Druggist, xx. 210) contained various erroneous statements respecting the amorphous, saponifiable alkaloid of A. napellus. These statements, the reports of which Mr Umney has declined to correct, conveyed to his auditors the false impression that the recognised proportion of the inactive, saponifiable base in question would suffice to double the proportion of benzoic acid produced on saponification, and hence would invalidate any process of assay based on that reaction (see page 233); whereas the fact is that in no investigation, the results of which liave been hitherto published, has the alleged inactive base been obtained free from aconitine, or in the considerable proportion erroneously asserted by Mr Umney, whose mistakes appear to have arisen in part through confusion be- tween the base in question with amorphous unsaponifiable aconite bases. ^ According to a more recent research by Jiirgens {Pharm. Zeit. , Sept. 1887), picraconitine has a constitution intermediate between aconitine and aconine. He states that picraconitine results from the splitting off of a single benzoyl-radical from aconitine, while the elimination of two benzo3'l- groups results in the formation of aconine; but that in the decomposition of aconitine, not only benzoyl but methyl groups are split off. No detailed account of this suggestive investigation appears to have been published. ' "The report that Morson's aconitine is pseudaconitine from Himalaya bikh tubers is now tolerably well disposed of, since Morson has made it known that his aconitine is prepared from the tubers of cultivated Aconitum Napellus" (Husemann, Pharm. Zeit., 1884). At one time, Morson's aconi- tine was certainly prepared from A, ferox. PSEUD AGON ITINE. 217 Pseudaconitine is readily obtained pure by dissolving the mixture of alkaloids isolated from the root of A ferox in dilute nitric acid, and then gradually dropping in strong nitric acid with constant stirring, until, by the separation of the nitrate of pseudaconitine, the liquid becomes thick. It is then drained by means of a filter-pump, and washed slightly with water containing 8 to 10 pel cent, of nitric acid. If a perfectly pure salt be re- quired, the product is purified by re-solution in the least possible quantity of hot water, cooling, and dropping in strong nitric acid till the salt crystallises ; when it is drained, pressed, and the alka- loid liberated by treating the solution with sodium carbonate Crystallised pseudaconitine contains C3gIl49NOi2 + Il20; t>ut the water of crystallisation is driven off below 100°.-^ Pseudaconitine presents a close resemblance to aconitine, both in its chemical and physiological characters.^ It is, however, more soluble in alcohol and ether than the latter base, crystallises with 1 aqua, and melts without darkening at a considerably lower temperature. The melting-point is about 104°-105° C, but is not well marked, fritting occurring a few degrees lower. When crystallised from ether, or a mixture of ether with petro- leum spirit, pseudaconitine forms transparent needles and sandy crystals ; but unless the evaporation is extremely gradual the base is apt to separate as a varnish at the upper edge of the solution, and soon forms a milk-white, cauliflower-like, crystalline efflorescence. Pseudaconitine and its salts (with the exception of the nitrate, BNO3 + 3H2O, and aurochloride) crystallise with difficulty, and the crystallisation is impeded, or wholly prevented, by very small admixtures of amorphous alkaloid or other impurity. Pseudaconitine Aurochloride, BHAUCI4, is distinctly crystalline when precipitated from a dilute solution. After drying over sulphuric acid it can be readily crystallised from boiling alcohol in minute needles only sparingly soluble in cold alcohol and which are anhydrous when air-dried. Pseudaconitine Chloroplatinate is soluble with moderate facility in water, and hence is not precipitated except from strong solu- tions. The mercuro-iodide, BHgIg, is amorphous, white, and very sparingly soluble. ^ Anhydro-pseudaconitine and acetyl-anhydro-pseudaconitine resemble the parent base in crystallising with IH.^O. 2 Pseudaconitine contains a somewhat different proportion of carbon from the other cr3'stalline aconite bases, and the aurochloride contains a somewhat different percentage of gold, but the best defined character of pseudaconitine is its behaviour on saponification. 218 VERATRIC ACID. Pseudaconitine is hydrolysed with great facility. The mere process of heating with dilute alcohol for the purpose of recrystal- lising it results in the production of a very sensible quantity of veratric acid and pseudaconine (page 219). Hence only a fraction of the alkaloid used crystallises out on cooling, and the mother-liquor yields veratric acid on acidifying, adding water, and shaking with ether. If freshly-precipitated pseudaconitine be boiled with ammonia or sodium carbonate for a few minutes, and the solution then acidulated and shaken with ether, a considerable quantity of veratric acid is dissolved out. When boiled under a reflux condenser for some hours with alcoholic potash, pseudaconi- tine is entirely converted into veratric acid and pseud- aconine or the products of the further decomposition of this base. The proportion of veratric acid obtained approximates closely to the theoretical amount (26'49 per cent.).^ By heating pseudaconitine to 100° for some hours with a strong solution of tartaric acid, it is completely converted into a n h y d r o- pseudaconitine, CggH^^NOi^ (page 205), a base which closely resembles the parent alkaloid. Veratric Acid, CgHioO^, or C6H3(OCH3)2.COOH.i This body has the constitution of adimethyl-protocatechuic acid. It melts at 174°— 175", and can be sublimed, but is not volatile with steam. It dissolves in 2100 parts of cold water, and in 160 parts at the boiling-point, and crystallises from a concentrated solution at about 50° in anhydrous needles, while crystals containing 1 aqua are deposited from very dilute solutions at any lower temperature. Veratric acid dissolves in alcohol and ether, and is readily extracted ' Possibly pseuJaconitine is not the only base contained in A. ferox which yields dimethyl-protocatechuic acid on sapoiiiRcation. W r i g li t and Luff {Jour. Chcm. Sop.., xxxiii. 174), when prepaiing =pui-e pseudaconitine nitrate by adding excess of nitric acid to the solution of the crude salt, obtained a nitric acid mother-liquor from which no crystals could be obtained. After dilution with water and separation of the i>recipitated resinous matter, sodium carbonate formed a copious precipitate which was freely soluble in ether, but which could not be made to crystallise or yield a crystalline salt. The base was recovered from etlier as a varnish, which on saponification yielded about 19 per cent, of dimethyl-protocatechuic acid, and was not destitute of physiological potency, though it produced far less lip-tingling than pseudaconitine, which can be readily obtained jmre by taking advantage of its very slight solubility in a liquid containing 8 to 10 per cent, of nitric acid. Since pure pseudaconitine yields 26J per cent, of veratric acid on saponification, Alder Wright is of opinion that this amor{)hous alkaloid probably consisted of about three-fourths of pseudaconitine and other saponifiable bases (possibly alteration-products of pseudaconitine), and one- fourth of non-saponifiable bases ; the amorphous bases preventing the crystallisation of whatever pseudaconitine was actually present. REACTIONS OF PSEUD ACONITINE. 219 by the latter solvent from its acidulated aqueous solution. It pro- duces no coloration with ferric chloride. When exactly neutralised with ammonia it gives a characteristic gelatinous silver salt on addition of a strong solution of silver nitrate. When veratric acid is fused with caustic potash and a little water at about 250° C, preferably in silver, it yields protocatechuic acid, CgH3(OH)2.COOH. If the melt be dissolved in water, the solu- tion acidulated with hydrochloric acid, shaken with ether, and the ether separated and evaporated, the solution of the residual proto- catechuic acid in warm water will be coloured an intense bluish green by ferric chloride, the -colour changing to dark red on adding sodium carbonate (compare Part I. page 62). With ferrous sulphate, a neutral solution of a protocatechuate gives a violet coloration. The formation of protocatechuic acid by fusion with caustic alkali forms a convenient test for pseudaconitine. It is only necessary to fuse the alkaloid with caustic potash and a little water at about 250° in a silver spoon, acidulate the solution of the melt, extract with ether, and test the ethereal residue with ferric chloride. Other reactions of pseudaconitine dependent on the veratroyl- group are the following : — If a small quantity of the alkaloid and a few drops of fuming nitric acid be evaporated to dryness, a yellow residue is obtained, which gives a beautiful purple-red colour when moistened with a solution of caustic potash in abso- lute alcohol. If pseudaconitine be heated with concentrated sulphuric acid to 100°, and a drop or two of a solution of vanadium sulphate added, a violet-red coloration is produced. Pseud ACONINE, C27ll4;^NOg, is contained in the aqueous liquid obtained by saponifying pseudaconitine with alcoholic potash, acidulating, and extracting the veratric acid by agitation with ether. It may be recovered by concentrating the solution, render- ing it alkaline by sodium carbonate, and agitating with ether. The base being moderately soluble in water, sodium carbonate produces no precipitate in dilute solutions ; and under these cir- cumstances ether extracts the base very imperfectly, but removes certain bye-products, and on subsequently concentrating the alka- line liquid the pseudaconine separates as a resinous mass. The last portions are readily obtained by evaporating the solution to dryness, and treating the residue with ether, while any aconine and colouring-matters soluble in chloroform will be left undissolved. Pseudaconine is left as a transparent resinous varnish on evapo- ration of its alcoholic or ethereal solution. On standing a few days the film from ether becomes changed into a mass of crystal- line needles ; but this effect is prevented by the presence of small 220 PSEUDACONINE. quantities of ether, alcohol, or other foreign matters. If the residue left on evaporating the ethereal solution be moistened with water a portion of the alkaloid dissolves, while the remainder becomes opaque, white and brittle, readily breaking up into particles having a pseudocrystalline appearance. The formation of this apparently crystalline product seems to be peculiar to pseudaconine and lycoctonine. Pseudaconine dissolves in water to form a solution which is strongly alkaline and very bitter, but it produces no tingling of the skin or lips, and its poisonous properties are very feebly marked. The aqueous solution precipitates silver nitrate, the precipitate being reduced on heating. It also reduces ammonio-nitrate of silver on boiling, but it dififers from aconine and japaconine in not reducing hot Fehling's solution, and by its solubility in ether. None of the salts of pseudaconine have been obtained in a crystal- line state. Japaconitine. Sesquianhydro-japaconitine. C. T^ N n ' nr n^ ' ^•^'-'•^6"5 This base is the crystalline alkaloid of Japanese aconite root.^ It was first isolated by Paul and Kingzett {Year-Book Pharm., 1877, 469), who ascribed to it the formula CggH^gNOg. Lubbe believes it to be identical with aconitine from A. Napellus, and to have the formula CggH^^NOig. The formula CggHgglSrgOgi is due to Wright and Luff {Jour. Gh&in. Soc, XXXV. 387; Yearbook Pharm., 1878, 490), who showed it to form crystallisable salts, and to be readily saponified with produc- tion of benzoic acid. As the alkaloid can be extracted from Japanese aconite root by alcohol alone, without the use of acid of any kind, it seems certain that the base has really the curious constitution attributed to it, or else that the hypothetical parent- base of the formula C33H47NO12, or €261139^^07(011)3.0711502, suffers dehydration by the mere process of concentrating its alcoholic solution. Japaconitine is readily obtained in long rhombic crystals, and ^ At least two distinct species of aconite are to be met with in the Japanese markets. Much of the root imported to England is said to have been steeped in salt and vinegar, and then dried in wood-ashes and the sun, to protect it against decay and the ravages of insects. In a root so treated, the alkaloid would be liable to be materially modified. (On " Japanese Aconite Root," see Pharm,Jour., [3], x. 149, 1020; xi. 149, 351, 1021, 1041.) JAPACONITINE. 221 forms a crystallisable nitrate, hydrochloride and hydrobromide. These salts are readily obtained crystalline by adding the dilute acid to a powdered crystal of the alkaloid contained in a watch- glass, and stirring the mixture. Solution to a clear fluid at first takes place, and on further stirring a crystalline magma is formed, just as occurs with aconitine. Japaconitine is dibasic, the salts containing two molecules of acid. Japaconitine presents the closest resemblance to aconitine, both in its physical and chemical characters. Its melting-point, 184°— 186°, differs only by a few degrees from that of aconitine. The proportions of carbon and hydrogen (compare page 205), and the percentage of gold in the aurochloride, are somewhat more tangible distinctions, but not of a very practical character. The crystalline form, as observed under the microscope, is a distinction of value, aconitine appearing in the form of hexagonal plates, and japaconitine in long columnar crystals (see illustrations to a paper by Richards and Rogers, Chemist and Druggist, May 18,1889). A method of distinguishing japaconitine from aconitine, and even of estimating the proportions of the two bases in a mixture, might be based on the behaviour of the alkaloids with benzoic anhydride. According to Alder Wright, when aconitine is heated to 100° for eight hours, with twice its weight of ben- zoic anhydride, it is converted into dibenzoyl-anhydro- a c o n i n e, 0251137^08(0711502)2 ; whereas japaconitine, when simi- larly treated, yields a t e tra-b enzoy la t ed derivative, ^26^39-^^7(^7^6^2)4* ^^ adding a minimum of alcohol to the product, and then agitating with aqueous tartaric acid and a large volume of ether, the excess of benzoic anhydride with benzoic acid and certain impurities are dissolved by the ether, while the separated aqueous liquid, when rendered alkaline, yields to ether the benzoylated alkaloids, which can be weighed after evaporating the solvent. On saponifying this product with alcoholic potash (page 204), the aconitine derivative will yield 33*40 per cent, of benzoic acid, while the benzoylated japaconitine will give 50 '7 8 per cent, of the same body. Japaconitine forms no anhydro-base when heated with aqueous tartaric acid. Japaconine, CggH^jNOjo, closely resembles aconine (page 214), and can only be distinguished therefrom by elementary analysis. Picraconitine. C31H45NO10. This base was isolated by T. B. Groves, together with aconi- tine, from a parcel of German roots purchased in 1874 as those of A, Napellus; but it appears doubtful whether there was not a 222 PICRACONITINE. large admixture of some other species, or whether the roots were not of abnormal character from some peculiarity of soil or climate. It has never been met with again, unless, as is not improbable, the bitter alkaloid of A, paniculatum consists of picraconitine. In any case, the possible presence of picraconitine in aconite root must not be ignored ; for, while the alkaloid resembles aconitine in yielding benzoic acid on saponification, it does not produce the lip-tingling so characteristic of the latter base, and is practically inert physiologically, half-grain doses having been taken internally without the production of any marked symptoms. Picraconitine is a bitter, amorphous resin, not fusible at 100°. The dilute solutions of its salts are not precipitated by ammonia, or caustic or carbonated fixed alkaloids, except on the application of heat, when the alkaloid separates as a thick coagulum fusible in boiling water. Picraconitine is soluble in ether and cliloroform. Picraconitine forms crystallisable salts. The hydrochloride crystallises readily from hot solutions in fine needles. A moderately strong solution of picraconitine hydrochloride, if satu- rated with ammonium chloride, becomes turbid on warming from a precipitate of the alkaloidal salt, which, on continuing the heat, is wholly deposited in fine needles. The test is also applicable to the nitrate, and probably to other salts of the alkaloid. Picraconitine gives no colour-reactions with the usual reagents. Its solutions are precipitated by tannin and Mayer's solution. The chloroplatinate is readily soluble, and the aurochloride forms a canary-yellow precipitate, not perceptibly crystalline, and exceed- ingly sparingly soluble in water. When boiled with alcoholic potash, picraconitine is saponi- fied with formation of benzoic acid and picraconine, Co^H^jNOg, an amorphous base nearly insoluble in ether, forming amorphous salts, and otherwise presenting the closest resemblance to aconine (compare footnote on page 216). Lyaconitine and Myoctonine. The root of Aconitum lycoctonum, a species of aconite growing in the Alps and Himalayas, bearing yellow flowers, has been found to contain two alkaloids which differ from the bases isolated from other aconites. So far, the products of the decomposition of these bases by alkalies have not been fully studied, and some obscurity rests on other of their characters. For the extraction of the bases of A. lycoctonum^ Dragen- dorff and Spohn {Pharm. Jour.^ [3], xv. 104) exhaust the roots with alcohol acidulated with tartaric acid. The tincture is concentrated, mixed with water, filtered, and repeatedly agitated LYACONITINE. 223 with ether while still acid. The ether removed traces of an acid resembling protocatechuic acid, but no benzoic acid could be detected. The liquor separated from the ether was treated with sodium bicarbonate and extracted with ether, which removed lyaconitine (1*13 per cent.). Subsequent agitation with chloroform removed the remainder of the lyaconitine, together with myoctonine (0'8 per cent.). The successive treatment with ether and chloroform removed all but traces of alkaloid from the solution. Neither base could be obtained crystallised. Lyaconitine^ was obtained, after further purification by ether of the base extracted as above, as a pale yellow resinous substance, yielding a white powder, and completely soluble in dilute acids After drying in vacuo, the base begins to melt at 111°'7, and is completely fused at 114°'8 (corrected), with partial decomposition. It is sparingly soluble in water ; very readily in absolute alcohol, chloroform, carbon disulphide and benzene ; less readily in ether ; and practically insoluble in petroleum spirit. A 10 per cent, solution of the base in alcohol shows a dextro-rota- tion, Sd= +31°"5. An aqueous solution of the nitrate shows S,= + 19°-4. The formula ascribed to lyaconitine by Dragendorff and Spohn isC2vH3,N206 + 2H20. None of the salts of lyaconitine have been obtained crystallised. The nitrate can be obtained and purified by dissolving the base in ether, and cautiously adding nitric acid mixed with ether. The nitrate is precipitated, the first fraction carrying down any colouring- matter contained in the solution. With-^strong sulphuric acid, lyaconitine gives a reddish brown coloration, and with syrupy phosphoric acid a violet coloration on warming. When treated with a mixture of 8 c.c. of water, 6 of strong sulphuric acid, and 0'3 of sodium selenate, lyaconitine is coloured a rose or pale reddish violet — a reaction which is not exhibited by the bases from other species of aconite. Lyaconitine is incompletely precipitated by caustic potash, alkaline carbonates and ammonia. Strong caustic alkalies partially decompose it. Thus, when warmed for a few minutes to a tem- perature of 35° C. with a 4 per cent, solution of caustic soda, lyaconitine dissolves, and crystalline lyaconine separates from the liquid, and may be extracted by ether. By agitation with chloro- form a second base can be extracted, while lycoctonic acid and a resinous substance remain dissolved.^ * Also called lycaconitine. 2 Lyaconitine and its salts being amorphous, their composition cannot be considered well-estahlislied. The formula attributed to lyaconine is remark- 224 LYCOCTONINE. Lyaconine, C27H4yN207 + 1 i aqua, is apparently ideutical with the base described by H U b s c h m a n n under the name of lycoc- tonine} It melts at 90°-92°, has an alkaline reaction, and an optical activity of Sd= +46°'4. It is very soluble in alcohol and chloroform, less readily in ether and benzene, and dissolves in about 250 parts of water. Its solution has an alkaline reaction, exhibits a fine blue fluorescence, is coloured purple by chlorine- water, and is precipitated by the ordinary alkaloidal reagents. The aurochloride, platinochloride and nitrate of the base have been prepared. AcoLYCTiNE, a base described by H ii b s c h m a n n, is probably able in containing an uneven number of atoms of hydrogen. Correcting it to contain H4g, and attributing to lyaconitine the formula CayHgoNgOg, the prin- cipal reaction occuriing by its reaction with soda would be : — 2C27H33N20a + 2H2O - C27H48N2O7 + C07H18N2O7 . ^ A specimen of " ly co ct onine," from A. lycoctonum, presented by H ii b s c h m a n n to F 1 ii c k i g e r, is described by the latter chemist ( Year- BooTc Pharm. , 1870, page 99, from Archiv. der Pharm., cxci.) as being crystal- lised in perfectly white and distinct prisms and needles, melting at 98°-104*' without darkening, and forming a transparent glassy mass on cooling. On contact with water this mass at once crystallised. The base was soluble in alcohol, ether, chloroform, amylic alcohol, petroleum spirit and carbon disalphide. By rapid evaporation from these solvents, the alkaloid formed a varnish which crystallised on contact with water ; but by slow evaporation crystalline tufts were obtained. The aqueous solution of the base had an alkaline reaction and intensely bitter taste. The physiological effects of lycoctonine were found to differ from those of the other aconite bases both in degree and kind. As a poison, lycoctonine was found much less energetic than aconitine. ^lercuric chloride, platinic chloride, phosphomolybdic acid and iodide of potassium produced no precipitate in solutions of lycoctonine salts ; but the base was thrown down by tannin, iodised potassium iodide, bromine- water (which gave a precipitate of microscopic needles) and the double iodides of potassium with mercury, bismuth and cadmium. Potassium mercuro-iodide threw down a precipitate which crystallised on standing, In solutions of 1 in 8000 no immediate effect was produced, but in about fifteen minutes beautiful crystals made their appearance ; and in a dilution of 1 in 20,000 they were formed in twenty-four hours. The precipitate was readily soluble in alcohol, and crystallised very beautifully from the solution. Mercuro-bromide of potassium does not affect lycoctonine solutions unless very concentrated, but both it and the mercuro-iodide throw down amorphous preci{)itates from solu- tions of aconitine, and do not affect narcotine solutions. With potassio-iodide of bismuth lycoctonine formed a precipitate in a dilution of 1 in 40,000. Sulphuric, nitric and phosphoric acids produced no colour-reactions. The nitrate of lycoctonine crystallised in tables, the sulphate in prisms. Solutions of the salts were not precipitated by caustic or carbonated alkalies, though the base itself was not notably soluble in alkalies. MYOCTONINE. 225 identical with the second base extracted by Dragendorff and S p h n from the product of the action of caustic alkali on lyaconitine. It is probably a product of the further action of the alkali on lyaconine (lycoctonine). It is described as a white powder, soluble in water, alcohol and chloroform, but insoluble in ether. It forms white precipitates with tannin and lead acetate, and a yellow with auric chloride. Its sulphate forms a white precipitate with ammonium molybdate. Acolyctine produces physiological effects similar to those of myoctonine, but less powerful. Lycoctonic Acid, C27lIjgN207, produced by the action of alkalies on lyaconitine (or by heating the base with water or dilute acid in a sealed tube), is crystallisable, and melts at 146°— 148°. It is sparingly soluble in water, moderately in ether, and readily in alcohol and chloroform. Myoctonine, according to Dragendorff and S p o h n, has the formula C27H30N2O8 + 5H2O, while Einberg regards it as C4oH5gN20i2 + 5H20, the water being lost on drying in a current of air at 60°. It is amorphous, has a bitter but not pungent or tingling taste, melts at 143°-144°, and is dextro-rotatory. (S^ for the alkaloid in 10 per cent, solution in alcohol = -|-29°*5 ; of the nitrate in aqueous solution 21°'2.) It is difficultly soluble in water, but very soluble in alcohol, amylic alcohol, acetic ether, chloroform, benzene, and carbon disulphide. Ether and petroleum spirit only dissolve traces of it. The salts refuse to crystallise. jMyoctonine is precipitated by most of the general reagents for alkaloids in solutions not too dilute, and may be titrated by Mayer's solution (1 c.c. = 0*0176 of alkaloid). An aqueous solution of myoctonine hydrochloride gives with excess of bromine-water an amorphous, very sparingly soluble precipitate, said to contain C^qK^^Bt^N 20-^2- If a fragment of myoctonine be moistened with fuming nitric acid and dried, the residue acquires a reddish brown colour on adding a drop of alcoholic potash (compare atropine). On heating to 100° with a 4 per cent, solution of soda, myoc- tonine is stated by Dragendorff and Spohn to behave similarly to lyaconitine, yielding lycoctonic acid, lya- conine, a base resembling acolyctine, and a fourth product of indefinite nature. The behaviour of myoctonine with caustic alkali has also been studied by F. Einberg (Inaugural Dissertation, Dorpat, 1887). When myoctonine was heated on the water-bath with 4 per cent, caustic soda solution, a spar- ingly soluble basic decomposition-product separated in crystals, which, when filtered off and purified, amounted to 24 per cent, of VOL. III. PART II. P 226 MYOCTONINE. the myoctonine taken.^ The filtrate was brownish, and had a peculiar pungent smell. When acidulated and shaken with ether, a body exhibiting a blue fluorescence was extracted ; and on evaporation 30'45 of a brownish serai-crystalline residue was obtained, in which Einberg recognised benzoic acid as the main constituent. The acid liquid, when rendered alkaline with sodium carbonate, yielded 11 '84 per cent, to ether and an additional 8"89 per cent, to chloroform, both solvents leaving amorphous yellowish brown residues on evaporation. According to S a 1 m o n o w i t z, myoctonine is a powerful poison resembling curare in its action, and acting most energetically when introduced directly into the circulation. The subcutaneous injec- tion of 0'075 gramme of the nitrate produced distinct toxic symptoms in cats, and the injection of 0*100 gramme always caused death in about half an hour. Mice were killed in three minutes by a dose of 0*001 gramme. Atisine. C^gH^^NgOg -, or perhaps Cc^^^^^^O^P' Atisine is the characteristic alkaloid of Aconitum lieterophyllum, a species of aconite which grows in the more temperate parts of the Himalayas.^ The atisine exists in the root in combination with aconitic acid. Atisine is described as white and uncrystallisable, becoming coloured and resinous on exposure to air, and melting at 85°. It ^ To this base, after drying at 80*, Einberg ascribed the formula C24H3gNOB, and considered it identical with Hiibschmann's lycoctonine. It melted at 94°, and had a rotation in absolute alcohol of +38°*9. It became amorphous when melted, reassuming the crystalline form on contact with steam. It dissolved in about 250 parts of water, 4 of absolute alcohol, 3 "4 of chloroform, 55 of ether, and 63 of benzene, which characters agree with those ascribed by Hiibsch- raann to lycoctonine. The base formed a crystalline nitrate, very hygroscopic and easily soluble in water. Strong sulphuric acid coloured the base bright yellow, changed to a fine orange on warming. ^ The formula C46H74N2O5 was deduced by the discoverer of atisine, J. Broughton, from an analysis of the platinum salt. It was confirmed (?) by Wasowicz by carbon and hydrogen determinations on the free base and by analyses, the nature of which are not stated, of the hydriodide, which led to the formula C48H74N2O4, HI + HoO {sic). On the other hand, C. R. A 1 d e r Wright found that the formula CgoHgiNOg agreed better with determinations of carbon, hydrogen, nitrogen and gold in the aurochloride of the base ex- tracted by him from a small batch of Atis roots ( Year-Book Pharm., 1879, 422). ' A. hsterophyllum bears flowers which are either wholly blue, or of a dirty yellow with purple stripes. In the bazaars of India the root is sold commonly as a popular bitter tonic, under the name of Atis or Atees root. The plant and root of A. heterophyllum have been fully described and figured by Wasowicz {Pharm. Jour., [3], x. 301, 341, 463). The root is apparently identical with ATISINE. 227 has a strong, pure, hitter taste, without any acrid or burning after- taste, and is not poisonous. The alkaloid is but little soluble in water or dilute spirit, but readily in strong alcohol, ether and benzene. When the alcoholic solution is strongly diluted with water, the greater part of the alkaloid is precipitated, and the liquid froths strongly on agitation. According to W a s o w i c z, strong sulphuric acid colours atisine a faint violet, which changes to red and dirty brown. Nitric acid produces a brown, sulphuric acid a red, and potassium bichromate a green coloration, with a distinct reddish violet zone. Shimoyama (Pharm. Jour., [3], xxvi. 86) obtained with some of the alkaloid prepared by Wasowicz a yellowish solution in concentrated sulphuric acid, gradually changing to a magnificent purple-red, which lasted several days, but became momentarily violet on adding a drop of water. No coloration was produced by nitric or hydro- chloric acid. Phosphoric acid dissolved the alkaloid without colour, but on warming the solution for some minutes it began to show a yellowish violet colour. Sulphuric acid and sugar produced at first a yellowish colour, which, after a few minutes, changed to yellowish red and then to carmine-red. The sulphate, nitrate and acetate of atisine do not appear to crystallise, but the hydrochloride, hydrobromide and hydriodide are crystallisable and sparingly soluble salts. Amrnohia precipitates atisine from the solutions of its salts in white flocks. Tannin gives a yellowish brown precipitate, and potassio-mercuric iodide a white precipitate, dissolving in alcohol to a solution which leaves a distinctly crystalline mass on evaporation. Atisine Hydriodide, BHI-f-HgO. When the precipitate of atisine mercuro-iodide is suspended in water, and decomposed by sulphuretted hydrogen, shining pearly scales of atisine hydriodide are deposited. These dissolve in a sufficiency of hot water, and are deposited again on cooling.^ The salt dissolves in 318 parts of water at 20°, and is very sparingly soluble in alcohol. Atisine Hydrochloride is a white crystalline powder, more "wakmali" or "bikmah," the former of which is regarded by Royle as the tuber of the poisonous A. palmatum, a view which Shimoyama {Pharm. Jour., [3], xvi. 86) regards as highly improbable. In anatomical characters, wakmah and atis roots exactly correspond, and they yield the same alkaloid. ^ When the mother-liquor is concentrated to a point at which no more crystals- are deposited on cooling, it still yields a precipitate with potassio-iodide of mercury, the alcoholic solution of which leaves an un crystallisable residue on evaporation. This behaviour appears to point towards the presence of a second alkaloid. 228 ASSAY OF ACONITE ROOT. soluble in water than the hydriodide. It has a strong bitter taste, but is free from the disagreeable after-taste of the latter salt. Assay of Aconite and its Preparations. The analytical assay and valuation of the alkaloids and other preparations of aconite yield very unsatisfactory results, not so much from the difficulty of isolating and identifying the alkaloids present, as from the uncertainty which exists between the amount and nature of the alkaloids obtained, and the physiological activity of the preparations yielding them. The most conflicting state- ments have been made respecting the relative activity of the actual alkaloids, even when these have been isolated in a crystalline con- dition ; but the evidence of later observers, especially Mandelin {Pharm. Jour., [3], xvi. 781), tends to show that the experiences of the earlier experimenters were due in part to the use of preparations containing a notable proportion of amorphous and relatively inert bases, to an insufficient number of physiological experiments, and ignorance of the fact that the age, sex, and general condition of an animal, besides its individual idiosyncrasy, materially afiPects its susceptibility to the poison. Man, again, is evidently more sensitive to aconitine than cats or dogs, and apparently old people are more susceptible than young (compare page 236). As a means of judging of the quality of aconite root, E. R. Squibb {Ephemeris, i. 125) recommends that a thin slice of definite section should be chewed in the lips, and the strength and length of the tingling sensation noted. A. B. Lyons has modified this test by employing one drop of a 10 per cent, tincture of the root. For liquid preparations, Squibb places 1 fluid drachm of a solution of the drug in the anterior part of the mouth, previously rinsed with water, and holds it there for one minute, when the mouth is emptied and again rinsed. A tenth of a minim of a 1 in 1 fluid extract, when examined in this way, should produce a distinct aconite sensation not amounting to tingling, but very suggestive of it, and continuing more or less for fifteen to thirty minutes. The total alkaloids contained in aconite root can be ascertained by processes substantially identical with those employed in preparing aconitine. The details of manipulation to be preferred have been investigated by E. H. F a r r and R. Wright (Pharm. Jour., [3], xxi. 1037). They recommend the exhaustion of the root by continuous percolation. One ounce (or 20 grammes) of the drug, reduced to coarse powder, is moistened with spirit of 0*890 specific gravity (which is preferable to either stronger or weaker alcohol), and packed in a conical percolator, when more of the TINCTURE OF ACONITE. 229 menstruum is gradually added, and percolation allowed to proceed slowly but continuously until 8 fluid ounces (or 160 c.c.) of percolate has been obtained. The tincture of aconite thus obtained is then evaporated over hot water to a low bulk, till all the alcohol is driven off. The residual liquid is allowed to cool ; some water added, if necessary, to reduce the viscosity; and then treated with 15 c.c. of decinormal sulphuric acid. The liquid is then filtered ; the precipitate washed with acidulated water ; and the filtrate shaken twice with chloro- form to remove colouring-matter. The separated chloroform is shaken with acidulated water to remove adherent traces of alkaloid, the aqueous liquid being added to the main quantity. The alkaloidal solution is then treated with a slight excess of potassium carbonate, and the alkaloids extracted by two agitations with chloroform, using 30 to 40 c.c. each time. The separated chloro- formic solution is washed with a little distilled water, and then evaporated or distilled over hot water, the residual alkaloids being dried at 1 00° C. till constant in weight. The alkaloids thus obtained are almost white, and vitreous in appearance. Prolonged exposure at the boiling-point of water causes a slight darkening in colour.^ The following proportions of total alkaloids were obtained by F a r r and. Wright by the above process. No. 1 sample was a root of Japanese origin ; one sample was of unknown origin ; and the rest were roots of A. Napellus grown in Germany. The extractive matter shown in the table was determined by evaporating a measured quantity of the tincture over hot water, and drying the residue at 100°. Sample. No. 1 (Japanese), . No. 2, No. 3, No. 4 No. 5 No. 6 No. i. No, 8 No. 9 No. lo: No. 11 Average, From 100 o.a of Tincture. Alkaloids. •073 •050 •063 •045 •070 •086 •082 •050 055 •062 Extract. 2-89 2-92 4-08 3-64 318 3^28 1-44 3^40 3^82 2 •46 312 From lOO Grammes OP Root. Alkaloids. •584 •368 •528 •400 •504 •360 •560 •388 •656 •400 •440 •496 These results show a much better yield of total alkaloids than ^ The foregoing process is, of course, directly applicable to commercial tincture and liniment of aconite. The extract should be treated with alcohol, 230 YIELD OF ACONITE ALKALOIDS. was obtained from the root of A. Napellus by C. R. Alder Wright, wlio extracted only '07 per cent., of which '03 per cent, was obtained in a distinctly crystalline form.^ From the root of Japanese aconite, Alder Wright obtained 0*25 per cent, of total alkaloids, of which 0'08 was crystallised. H a g e r found from 0'05 to 0*40 of cry stalli sable alkaloid, with a total yield of 0'6-i to 1*25 per cent. W. Procter found 0'46 per cent, of total alkaloid in American root {A. Napellus), but only 0'20 in root of German growth. From the flowers of A. ^;am'cz^Za^Mm, E. L. Cleaver extracted 0'9 per cent, of total alkaloids (bitter, not tingling) ; from the leaves O'l per cent. ; and from the extract of the whole ])lant 0'3 per cent. Richards and Rogers {Chemist and Druggist, Feb. 14, 1891) extracted 0*57 per cent, of crystallised aconitine from dry Japanese aconite root; 0*14 per cent, from dry root of A. Napellus ; and 0'71 per cent, from fresli roots (both wild and cultivated) of the same species. These results suggest a notable loss of (crystallisable) alkaloid during the process of drying. Ail the foregoing estimations were made by fairly reliable methods, and show that the proportion of alkaloids in aconite varies widely, being probably largely affected by the time of collection, the age of the plant, and possibly by the climate and soil. The method of extraction profoundly affects the nature as well as the amount of alkaloids obtained ; any heat or employment of mineral acids tending to effect hydrolysis of the crystalline alkaloids with formation of amorphous bases. A. B. Lyons found the moisture of aconite root to range from 8'2 to ir2 per cent., and the extractive yielded to alcohol to vary from 9'3 to 19"8 per cent. The alkaloid from 10 grammes of the root required from 3*7 to 10*8 c.c. of ,J Mayer's solution for its precipitation. A striking example of the effect of the process of extraction on the character and proportion of the alkaloids obtained is afforded by the following results of C. Schneider {Archiv der Pharm.y ccxix. Xo. 5), obtained with the same sample of aconite root: — and the liquid filtered and proceeded with like that percolated from the root The ointment can be treated similarly. The leaves and other parts of the aconite p?a?i^ can be assayed in a manner similar to that employed for the root. ^ A still smaller yield of alkaloid was obtained by Alder Wright and Rennie from the fresh (English) herb (flowers, leaves and stalks), namely, about 0'05 per cent, calculated oji the dry herb, and of this only a small fractiou could be obtained crystallised {Year- Book Fharm., 1880, 455). EXTKACTION OF ACONITE ALKALOIDS. 231 Process Employed. Character 0/ Alkaloid. Percentage. British Pharmacopoeia (1867), Morton's, .... Hirzel'8, . . Wittstein's, .... Hottot and Li^gois', . Duquesuel's, . Light yellow powder. Well-formed, isolated, six-sided tablets. Crystals. Well-developed crystals. •002 •127 •0046 •140 •296 •339 The good results obtained by Duquesnol's process were doubtless due to extraction by percolation with cold alcohol, acidulated with tartaric acid, while all the others employ more or less heat, some with and some without sulphuric acid. A solution of potassio- iodide of mercury (Mayer's reagent) may be employed for the volumetric determination of aconite alkaloids in acid solution. The difficulty attending the use of the process is the uncertainty of the factor to be employed where there is no knowledge of the composition of the alkaloid present.^ Mayer's reagent may be used for the concentration of the aconite bases. The precipitate is filtered off, washed, suspended in water, and decomposed by a stream of sulphuretted hydrogen. The filtered liquid is treated with an alkaline carbonate, and shaken with ether or chloroform; the extracted base being recovered by evaporation in the usual way.^ Where the alkaloids of aconite have been extracted and obtained in a fairly pure condition, they may be determined by titration with standard acid and methyl-orange. Operating in the manner described on page 131, the author found that very accurate deter- minations could be made. Thus 30 milligrammes of crystallised ^ By titration with Mayer's reagent, Z i n o f f s k y examined the aconites cultivated at Dorpat in 1871. Of the portions of the plants above ground he found the flowers always richest and the stalks poorest in alkaloid ; the lowest occuiiying au intermediate place, and containing, when fresh, about 80 per cent, of water, and from 0'167 to 0"271 per cent, of alkaloid. The highest proportion of alkaloid was 0729, found in the fresh flowers (collected at the end of July) from A. Stoerckianum. By the assay, apparently by Mayer's solution, of entire aconite plants (including the roots) collected at Dorpat Botanical Gardens in June 1871, F. Dragendorff {Quelques Drogues Actives) found proportions of alkaloid ranging from 0*054 to 0*327 per cent, in the fresh substance containing about 80 per cent, of water, and from 0"195 to 0*844 calculated on the dry material. 2 In a private communication to the author, Alder Wright states that there is some reason for supposing that the crystallisable bases are apt to be more or less altered by this treatment, and rendered uncrystallisable. 232 TITKATION OF ACONITE ALKALOIDS. aconitine was dissolved in 15 c.c. of (neutral) ether; 3 c.c. of water containing a drop of a j^ per cent, solution of methyl- orange (previously rendered sensibly pink by a minute addition of acid) added; and g hydrochloric acid dropped in from an accurately divided pipette, shaking well after each addition, till a permanent red coloration of the aqueous layer was obtained. Two experi- ments made in this manner showed 29*9 and 31-0 milligrammes of aconitine, against 30 taken ; while 30 milligrammes of japaconi- tine (not quite pure) showed 29-8 by titration. 1 C.C. of ^ acid neutralises 12-94 miUigrammes of aconitine. ,, ,, 10*86 ,, aconine. ,, „ 14*14 ,, pseiidaconitine. ,, ,, 10*46 „ pseudaconine. „ ,, 12*44 „ japaconitine. ,, ,, 10*54 „ japaconine. The determination of the total alkaloids of an aconite prepara- tion is in itself of little value if any as a criterion of its activity. It is rather the first step in the process of assay, the potency of the preparation substantially depending on the results subsequently obtained.'^ ^ Where the amount of material is suflBcient it is very desirable to isolate the crystallisable alkaloid ; and if this could be eflfected with an approach to quantitative accuracy, it would probably furnish the most reliable criterion of the physiological activity of the substance. In practice, however, very great difficulties attend such a method of examination. In the first place, there is always a danger that the maximum yield of crystals may not be obtained, and hence that the activity of the preparation will be seriously under-estimated. But, apart from this source of error, there exists the grave difficulty that the amount of substance which is commonly available, or can be conveniently submitted to examination, yields a quantity of total alkaloids far too small to render any method based on crystallisation practically available. In the manufacturing laboratory, where comparatively large quantities of material are available, a good and simple method of effecting at least a partial separation of the crystallisable alkaloids, and which has the advantage of being equally applicable to aconitine, pseudaconitine and japaconitine, is as follows : — The ethereal residue is redissolved in ether in a small beaker. The solution is then stirred with a glass rod which has been dipped in nitric acid, or with a jupette from the orifice of which the acid is allowed to trickle very slowly. At each addition of the acid a white cloud of the alkaloidal nitrate will be produced, which ceases to appear when the acid has been added in excess. After standing a few minutes, all the nitrate formed collects as a crystalline maj>s on the bottom and sides of the beaker, and the ether may be poured off. The nitrate may be purified by dissolving it in a minimum of hot water, allowing the liquid to become cold, and then adding nitric acid, drop by drop, with constant stirring, until no further separation of crystals takes place. ASSAY OF ACONITE ALKALOIDS. 233 The only principle of assay hitherto proposed for the aconite alkaloids, making any attempt to discriminate between them and estimate the activity of a mixture, is that based on saponification of the active bases. A method of this kind was suggested by Alder Wright, who proved that the saponification of aconitine, pseudaconitine and japaconitine occurred with a near approach to quantitative accuracy (page 204). A method of assay based on the saponification of the crystallis- able alkaloids of aconite, has the great advantage of distinguishing sharply between the three principal poisonous aconite bases on the one hand, and the comparatively inactive products of their decom- position on the other. As it is generally accepted that aconine has only g^^ of the physiological activity of aconitine, and that japaconine and pseudaconine bear a similar relation to their respec- tive parent alkaloids, it may be assumed that the activity of a mixture of aconite alkaloids is substantially represented by the proportion of crystallisable saponifiable base present;^ and, there- fore, the determination of the latter with reasonable accuracy is a considerable advance towards the solution of the problem of the assay of aconite preparations.^ The salt is then drained and pressed between filter-paper, dissolved in warm water, sodium bicarbonate added, the liberated alkaloid extracted with ether, the ethereal solution separated and evaporated, and the residue weighed. ^ It is true that the bitter non-poisonous alkaloid, ]jicraconitine, is saponi- fiable ; but it has only been met with on one occasion (1874, see page 221), unless it is identical with the imperfectly-examined bitter alkaloid obtained by E. L. Cleaver from the root of A. paniculatum. Lyaconitine and myoctonine, the amorphous alkaloids of A. lycoctonum, are saponifiable, but are of no practical interest. Both Alder Wright and A. Jiirgens found a small quantity of an amorphous saponifiable alkaloid in A. Napellus^ and J. C. Umney has stated that unpublished experiments of his confirm this conclusion. But neither Wright nor Jiirgens succeeded in preparing the base in question quite free from aconitine, and the quantity isolated was too small to allow of complete examination. How far these little-known bodies have a practical bearing on the saponification-process of assay is uncer- tain, and hence the results must be regarded as tentative, except where the method is applied to the alkaloid previously obtained in a crystallised state. 2 Alder Wright holds strongly that all galenical preparations of aconite and amorphous alkaloids should be abandoned, and only well-crystallised alka- loids or their salts employed. It is a grave scandal that, although the enormous diff'erence in physiological jiotency between the crystalline alkaloids of the aconites and the amorphous bases associated with them, or produced by their decomposition, has been long recognised, and become generally known, and while crystalline aconitine can be readily prepared, that a preparation should still be sold under the name of "aconitine" which is not crystallised, a^d contains a large proportion of 234 ASSAY OF ACONITE ALKALOIDS. Alder Wright's saponification experiments were made on comparatively large quantities of the alkaloids ; but to be of any practical value the method of assay must be available with a quantity of aconite bases not exceeding 50 milligrammes, and should even be applicable with half that quantity. The author has succeeded in making very satisfactory determinations on these small quantities by the following method of operating, which may be conveniently applied either to an ether or chloroform residue, or to the liquid resulting from the titration of either of these with standard acid and methyl-orange, as already described. The residue or solution, containing 30 to 80 milligrammes of alkaloid, is treated with 20 c.c. of rectified spirit (neutral to phenolphthalei'n) and 3 c.c, of a solution of caustic soda in an equal weight of water. The liquid is then boiled for an hour in a flask under a reflux condenser, after which the alcohol is distilled ofi*, and the residual liquid acidulated with hydrochloric acid. The liberated benzoic or veratric acid is extracted by agitation with about 15 c.c. of ether, and the ethereal solution separated and washed with succes- sive small quantities of water, until the washings show their freedom from mineral acid by ceasing to redden litmus. The ethereal liquid is then separated and transferred to a small stoppered cylinder (25 c.c. capacity) ; about 5 c.c. of water faintly coloured with phenolphthaleiii added ; and ^ normal baryta- water dropped in from a finely-divided pipette until the aqueous layer acquires a pink colour, which is not destroyed by agitation with the ethereal stratum. From the volume of standard baryta consumed, the amount of aromatic acid resulting from the saponification can be calculated. One c.c. of ^ baryta neutralises 2'44 milligrammes of benzoic acid, or 3*64 milligrammes of veratric (dimethyl-pro tocatechuic) acid. Although these acids have different combining weights, the volumes of alkali neutralised by equivalent weights of them are, of course, identical ; and hence no grave difference results in, calculating the saponifiable alkaloid, whether benzoic or veratric acid has been pro- duced by the saponification. Thus : — 1 c.c. of g5 baryta represents 12*94 milligrammes of acoiiitine saponified. i> n 14*14 ,, ])seudaconitine saponified. n ,, 12*44 ,, japaconitine sa[)Oinfitd. In three experiments, where a weight of 30 milligrammes of the practically inactive base. It is a question whether the sale of such an impure preparation as **aconitine" is not an infringement of the Sale of Food and Drugs Act, notwithstanding that the British Fharviacopceia officially recog- nises the indefinite mixture as " aconitiue," and describes it as "usually amorphous." ASSAY OF ACONITE ALKALOIDS. 235 same sample of crystallised aconitine was saponified, the baryta solution used represented 3r6, 28*3 and 30-9 of the alkaloid. In the case of japaconitine (not quite pure) the process indicated 29"8, against 30 milligrammes taken. If desired, the titration being completed, hydrochloric acid may be added, when the aromatic acid will be liberated and redissolved by the ether. On separating this solution and allowing it to evaporate spontaneously, the weight of the acid may be ascertained and its melting-point observed ; or the ether may be separated from the aqueous liquid, and the latter acidulated, largely diluted and distilled, when a separation of the benzoic and veratric acids will be effected, the former volatilising with the steam and the latter r^iaining in the retort. This difference of behaviour enables pseudaconitine to be recognised and estimated in presence of aconitine and japaconitine. By the foregoing method of assaying the mixed alkaloids from the tincture of A. Naj^elliLS root,^ G. E. Scott-Smith obtained in the author's laboratory the following results : — A. B. C. D. E. F. G. fl. Weight taken, iu milligrammes, . 55-0 51-7 21-9 87-0 21-0 31-5 17-2 23-6 Alkaloid by titration (iu temis of ) aconitine), ) 69-0 66-7 29-4 ... 28-8 ... 18-1 24-9 Benzoic acid, 5-2 4-0 8-4 ... 4-8 4 1 =Aconitine, 27-7 20-4 ... 44-5 ... 25-7 22-1 Percentage of saponiflable alkaloid, 50-4 39-5 51-1 ... 81-6 56-1 If desired, the basic product of the saponification can be isolated by rendering the liquid alkaline with sodium carbonate or caustic soda, and agitating with ether or chloroform. The latter solvent extracts a trifling further quantity from the liquid which has already been treated with ether. The few experiments made in this direction in the author's laboratory gave somewhat erratic results, probably owing to the imperfect extraction of the bases by immiscible solvents, and the further action of the caustic alkali on them. * The alkaloids from a tincture prepared from the root of A.ferox gave, for 767 milligrammes taken : — By titration, 74*9 of alkaloid, calculated as pseud- aconitine ; saponified, 14 '3 milligrammes of veratric acid by titration, against a weight of IS'O extracted by ether. The former result represents 55-1 of pseudaconitine, leaving 21*6 of unsaponifiable alkaloid. The basic product of the saponification extracted by ether, followed by chloroform, from the alkaline residue, amounted to 18 '5 milligrammes, and neutralised acid equivalent to 51 '4 of pseudaconine, or 69*4 of pseudaconitine. 236 POISONING BY ACONITE. Toxicology of Aconite. Aconitine is one of the most violent poisons known, and pseud- aconitine appears to be fully as active ; whereas picraconitine, atesine, and some others of the natural alkaloids of the aconites appear to be harmless bitter principles. The bases produced by the saponification of the poisonous alkaloids are also comparatively inert (t^Jq ^^ ^^^ toxicity of aconitine), and it is probably to the presence of these and other relatively inactive bodies, in variable pro- portion, in the so-called " aconitine " of commerce that the notorious uncertainty in the activity of that preparation is largely due. Some of the recorded variations verge on the fabulous, and are probably in some measure due to the experiments being insufficient in number, and made without due regard to the difference in susceptibility to the poison caused by age, sex, and general condition of the animals operated on.^ A more reliable preparation is obtainable since the conditions and importance of obtaining crystallised aconitine, and of preparing the base from certain definite species of aconite, have become more generally recognised.^ From certain ^ K. F. Man del in states [Pharm. Jour., [3], xvi. 781), as the lesult of very numerous experiments both on frogs and warm-blooded animals, that not only do animals of different species behave dissimilarly, but even with animals of the same species a considerable difference can frequently be observed in respect to the lethal dose, according to the age and condition of nourishment. With frogs, in particular, considerable differences are observable ; and female frogs are more susceptible to the poison than males. Old animals are more susceptible than youDg ones ; and the symptoms may vary according to the individuality aud nourishment of the animals experimented on. 2 Some interesting results of the action on sparrows of the principal makes of aconitine prepared in 1872 have been described by H. D u q u e s n e 1 ( Year- Book Pharm., 1872, page 241). Administered by subcutaneous injection, in a dose of 0*0005 gramme in 10 drops of slightly acidulated water, crystallised aconitine produced death in 1 minute ; the alkaloid of the French Codex (Hottot's preparation), in 15 minutes ; Merck's aconitine, in 75 minutes ; French commercial aconitine, in 120 minutes ; and Hubschmann's napelline (probably impure aconine), profound sleep, not followed by death. Hottot's aconitine is described as amorphous, white, pulverulent, containing 20 per cent, of water, fusible at 80°, and assuming after loss of water a resinous trans- parent appearance, but not forming crystallisable salts. P. C. Plugge (Archiv der Pharm., Jan. 1882) was led to investigate the relative toxicity of commercial * ' aconi tines " in consequence of a death from the accidental dispensing of Petit's preparation, instead of Friedlander's, which was intended but not specified by the prescriber. Plugge found the •elative activities to be, Petit's nitrate of aconitine, 170 ; Merck's nitrate of aconitine, 20 to 30 ; Friedlander's aconitine, 1. He placed the various com- mercial specimens in the following order, commencing with the strongest : — POISONING BY ACONITE. 237 observations of Richards and Rogers {Chemist and Druggist, Feb. 7 and 14, 1891), it is not improbable that commercial crystallised aconitine sometimes contains a large admixture of anhydro-aconitiue, and that this base is considerably more active than the parent alkaloid (A. H. Allen, PTiarm. Jour., [3], xxii.). The poisonous effects of aconite and its preparations appear to be entirely due to the characteristic alkaloids contained therein,^ and are generally assumed to be substantially the same in kind and degree, whether aconitine itself, or one of its analogues, pseud- aconitine or^japaconitine, be the base present.^ This, however, is by no means certain. Petit's, Morson's, Hottot's, Hopkins and Williams', Merck's, Schuchardt's^ Friedlander's. E. R. Squibb (Ephemeris, i. 135) in 1882 classified the four chief makes of aconitine as follows : — Duquesnel's crystallised aconitine, 111 ; Merck's "aconitine" from Himalaya root (pseudaconitine), 83; Merck's ordinary aconitine, 8 ; aconitine of unknown make, 1 ; powdered aconite root, 1. F. A. T h m p s o n, by employing Squibb's physiological test, classified various samples of commercial aconitine as follows : — Gehe's crystals, 480 ; Merck's, 350 ; Duquesnel's, 300 ; Gehe's amorphous alkaloid, 90 to 45. Buntzen and Mad sen {Pharm. Jour., [3], xvi. 366) concluded from experiments on frogs that Gehe's amorphous aconite was the most powerful of the specimens examined. Next came some preparations made from Vosges roots ; then the crystalline preparations of Gehe, Petit, and Merck ; and after- wards preparations by Madsen from Swiss roots. Duquesnel's aconitine gave far less effective results than other observers have stated. Great differences were observed in samples of alkaloid from Japanese roots, while that from bish root (pseudaconitine) was inferior in quality, though this may have been due to the roots having been submitted to the action of heat. ^ H. Duquesnel found that an alcoholic extract of aconite root, from which the alkaloid had been removed in the ordinary way by agitating the alkaline solution with ether, when administered to birds produced a sound sleep of several hours, without anaesthesia, followed by complete recovery. Larger doses were fatal. The extract employed by Duquesnel probably con- tained aconine, which is imperfectly extracted by ether. Hiibschmann's "napelline," which was probably impure aconine, produced similar symptoms. Duquesnel's extract would also contain aconitic acid, which Fleming found to have but little effect when administered to rabbits hypodermically. Torsellini, however, found aconitic acid to have a paralysing effect on the heart of a frog. ^Mandelin {Pharm. t/bttr., [3], xvi. 782) disputes the statement of Langgaard, that japaconitine is " one of the strongest of poisons, which exceeds aconitine and pseudaconitine in activity." He even doubts the chemical difference between aconitine and japaconitine, and finds in both cases the lethal dose for frogs to range from 1*2 to 2*4 milligrammes per kilogramme of body weight ; for guinea-pigs, 0'05 milligramme; and for dogs and cats, 0*06 to 0*075 milligramme per 1000 grammes. 238 FATAL DOSE OF ACONITINE. Poisoning of human beings by pure aconitine has been of comparatively rare occurrence; but there have been numerous cases of poisoning by the roots, leaves, and galenical preparations of aconite, the greater number being the result of accident.^ The root has been occasionally eaten in mistake for horse-radish, which it somewhat resembles (compare page 199). The medicinal dose of the B.P. tincture oi aconite is from 5 to 1 5 minims. A. Wynter Blyth considers twice the maximum dose, or 30 minims, likely to be fatal to an adult, though the least fatal dose is usually stated at above twice this measure. Fleming's tincture of aconite is from three to six times the strength of the B.P. preparation.^ The B.P. liniment is eight times as strong as the tincture.^ The fatal dose of aconitine is difficult to fix, as in the few cases in which a fatal dose of the pure alkaloid has been administered the quantity taken has not been known ; and in the cases of poisoning by preparations of aconite there is the greatest uncertainty as to the amount of alkaloid contained therein. Headland considers -^ grain of aconitine an ordinary fatal dose for an adult, and ^^ grain of the nitrate has actually caused death. Death appears to have been caused in one hour by 0*0005 gramme of aconitine (Pharm. Jour., [3], xx. 734). Wynter Blyth con- siders "002 gramme or '03 grain the minimum fatal dose for an adult, when the poison is taken by the mouth ; but that if given hypodermically, 0"0015 gramme would probably kill, since the whole of. the poison is then thrown on the circulation at one time, and there is no chance of its elimination by vomiting. P e r e i r a relates a case in which ^ grain nearly proved fatal to an elderly lady. Recovery has occurred after taking 2J grains, but in this case there was violent vomiting immediately, and most dangerous ^ A. Wynter Blyth, in his work on Poisons, states that he had collected from European literature, of the ten years prior to 1874, eighty-seven cases of poisoning hy aconite in some form or other. In these were two cases of murder, seven of suicide, and seventy-seven more or less accidental. Six of the cases were from the use of the alkaloid itself ; ten from the root ; in two cases children eat the flowers ; in one case the leaves of the plant were cooked and eaten by mistake ; in seven the tincture was mistaken for sherry, brandy, or liqueur ; and the remainder were caused by the tincture, the liniment, or the extract. 2 Dr Male, of Birmingham, died from the effects of 80 drops of Fleming's tincture, taken in ten doses of 8 drops each, in the course of four days. 3 Dr C. Vachell, of CardifT, has published a case of fatal poisoning by 2 grains of extract of aconite taken in pills. This was the maximum dose of extract according to the British Pharmacoposia of 1867, but in the edition of 1886 the dose is stated at ^ to 1 grain. SYMPTOMS OF ACONITE POISONING. 239 symptoms for thirty hours.^ In the Lamson case {Gwjs Hospital Reports, 1883, page 307) the victim probably received about 2 grains.^ The symptoms of aconite poisoning usually begin to manifest themselves a few minutes after the poison is taken, and are, in some respects, quite peculiar and characteristic. They usually, but not invariably, commence with a tingling and numbness of the lijis, tongue, gums, and throat, accompanied with a burning sensation in the stomach. These effects are succeeded by tingling and creep- ing sensations in various parts of the body, pains in the abdomen, headache, vertigo, and nausea, frequently accompanied by vomiting and sometimes by purging. There is, also, diminished sensibility of the skin, constriction in the throat, frothing at the mouth, partial or entire loss of voice, impaired vision, ringing in the ears, and feeling of tightness in various parts of the body ; muscular tremors, cold perspirations, loss of muscular power, and great prostration generally. Sometimes there is alternate contraction and dilation of the pupil. The most constant symptoms of aconite poisoning are difficulty in breathing, progressive muscular weakness, a weak intermittent pulse, and, in most cases, vomiting, especially when the poison has been taken by the mouth, instead of subcutaneously. Death usually occurs from syncope, preceded in some cases by delirium and con- vulsions. Convulsions occurred in ten cases out of ninety-four collected by Drs Tucker and Eeichert,^ and opisthotonos happens ^ In a case of poisoning by aconite an emetic should be at once given, or the stomach-pump promptly used. Stimulants may be given with advantage. Animal cliarcoal, to be afterwards removed by the stomach-pump, has been recommended. Strychnine and digitalis have been used successfully as antidotes, and a solution of iodised iodide of potassium has been suggested, 2 In 1881, a medical man named Lamson gave his brother-in-law, P. ]M. John, a youth of 19, paralysed below the pelvis, a dose of Morson's aconitine, contained in a gelatin capsule. Some twenty or thirty minutes after, John was seized with pain in the stomach, which he at first called heartburn. He then vomited, and suffered great pain, complained of the skin of his face being drawn, of a sense of constriction in the throat, and of being unable to swallow. He retched violently, and vomited a small quantity of dark brown fluid. Injections of morphine gave some relief, but the symptoms returned, and he was with difficulty kept down by two men. Death occurred four hours after administration of the poison, and the victim was conscious almost to the last. * These symptoms probably depend largely on the dose taken. "With large doses, the heart's action is arrested before the poison has had time to materially affect the excitability of the motor nerves, and the heart once stopped, further absorption is diminislied or arrested. 240 DETECTION OF ACONITE POISONING. occasionally. Death from aconite poisoning commonly ensues in from two to six hours, though there is considerable variation in this respect.^ The post-mortem appearances from aconite poisoning are by no means characteristic. They are congestion of the lungs and liver, with an injected condition of the brain and its membranes. There is more or less redness of the stomach and intestines, which are frequently found empty. Great redness of the stomach and intestines is sometimes the only abnormal appearance after aconite poisoning, and this does not occur when the poison has been given hypodermically. The right side of the heart usually contains more or less blood, and the blood throughout the body is generally fluid and dark in colour.- TOXICOLOGICAL DETECTION OF AcONITE. In any case of suspected poisoning by aconite or its preparations, the symptoms presented before and after death are of the utmost importance.^ The poison is so violent, so readily decomposed, and so wanting in delicate and characteristic chemical reactions, that there is but little hope of detecting it in the body by chemical analysis. With care, however, this may sometimes be effected, and if the chemical reactions be distinctly confirmed by a physiological test, the presence of the poison may be considered definitely proved. The aconite alkaloids have been recovered from the urine, the blood, and the liver, and have been detected in the stomach several months after death ; but the poison has been destroyed in cases where the viscera have become and remained alkaline for some time from putrefactive decomposition. In cases of supposed poisoning by aconite, the stomach and intestines should be carefully examined for portions of the leaves or other parts of the plant ; which, if found, may be identified by ^ In five cases of aconite poisoning recorded by J. W. Mallet, death ensued respectively in 8, 10, 15, 75, and 135 minutes, while in a sixth case it did not occur till four days after the poison was taken. 2 In the Lamson case, sixty-four hours after death, there was great redness and inflammation of the cardiac end of the stomach, which had a bUstered appearance, the mucous membrane showing in "places small, slightly raised, yellowish grey patches. The duodenum was greatly congested, and there were congested patches in other parts of the small intestine. The brain and its membranes were slightly congested, and the lungs much so, especially towards the posterior parts. The heart was very flaccid, nearly empty, and stained with blood-pigment. Tlie pupils were dilated, and the lips and tongue pale. The bladder contained three or four ounces of urine. ^ It is for this reason that the symptoms of aconite poisoning are described in the text at greater lengtli than would appear necessary in a work treating of the chemist's duties ratiier than those of the medical practitioner. DETECTION OF ACONITE POISONING. 241 comparison of their botanical characters with those of real aconite. The fragments may be washed with a little distilled water, and masticated with the front teeth, when the persistent tingling and numbness so characteristic of aconite will be distinctly recognisable. For the isolation of aconite bases in cases of poisoning, the suspected matters should be finely divided and treated at the ordinary temperature with strong alcohol, which should be slightly acidulated with tartaric acid, unless already distinctly acid. The liquid is strained and evaporated to a low bulk at a temperature not exceeding 40° C. The residual liquid is filtered cold, acidulated with tartaric acid, if requisite, shaken with ether, separated, and rendered alkaline with sodium carbonate. The alkaloids are then extracted by agitation with ether or ether-chloroform, the solution washed by agitation with water, and evaporated at a gentle heat. The alkaloidal residue having been obtained, it should be dis- solved in a few drops of water acidulated with acetic acid, and a drop of the solution placed on the tip of the tongue or inside the lower lip. E. R. Squibb recommends that the quantity to be tasted should be dissolved in about 60 drops of water, which is then held in the front part of the mouth (previously rinsed) for one minute, and then discharged. Another good plan is to drop the solution on a fragment of porous biscuit, which is then chewed with the front teeth. If any aconitine or other poisonous aconite base be present it will produce, in a period of time not exceeding fifteen minutes, a marked tingling sensation of the tongue and lips (somewhat similar to the effect produced by scalding the tongue with hot tea) ; and, if the quantity be sufficient and the liquid has reached the tonsils a distinct sensation of sore throat will be observed. These effects last for a considerable time, and are pro- duced in a most marked and unmistakable manner by a single drop of the B.P. tincture of aconite, corresponding to \ grain of the root, and probably not more than j^qq grain of total alkaloids. The effect is so characteristic and delicate that it constitutes by far the best test for the presence of the poison. If not produced it is practically useless to apply other tests, as, in the absence of the physiological reaction they would at least be inconclusive ; but, having obtained the characteristic tingling sensation, the chemical tests often afford useful confirmation, and enable the analyst to form an opinion as to whether pure aconitine or a galenical preparation of the aconite plant was taken.^ ^ An interesting case of this kind has occurred in the author's personal experience. A man of suicidal tendencies was suddenly taken violently ill at a country inn. He suffered from difficulty of respiration and inability to use his limbs, especially on one side, had violent convulsions, and died before VOL. III. PART II. Q 242 DETECTION OF ACONITE POISONING. The chemical tests should be applied to single drops of the acidulated solution placed on microscope-slides ; or, in the case of the colour-tests, to the residues left on evaporating a few drops at a gentle heat on the inside of a porcelain crucible cover (compare page 145). The reactions which may prove of service are : — 1. The formation of a crystalline nitrate on adding a small drop of nitric acid at the end of a glass rod (page 210). 2. The formation of a crystalline aurochloride on adding a drop of auric chloride (page 211). 3. The formation of crystals of aconitine hydriodide on adding a minute fragment of potassium iodide, and allowing the solution to evaporate (page 212). 4. On adding cold concentrated sulphuric acid to the aconite residue no reaction is produced immediately, but very gradually, or more rapidly on cautiously warming, a deep brown coloration is produced, passing through various shades of reddish brown to violet. The reaction is not produced by pure aconitine. 5. In presence of certain impurities, which adhere tenaciously, aconite bases develop a well-marked cherry-red coloration, changing to crimson, when treated with sugar and sulphuric acid in the manner described under morphine. The mixture of bases extracted from aconite root in the ordinary process of assay gives this reac- tion very distinctly. 6. Impure residues of aconite bases, when treated with syrupy phosphoric acid, give a violet coloration when the mixture is heated for some time on the water-bath, so as gradually to concen- trate the acid. 7. Aconitine yields with phosphomolybdic acid (Sonnenschein's reagent) a yellow precipitate, which, in the presence of impurities, dissolves in ammonia with blue colour. When the tongue-test renders the presence of an aconite base probable, it is very desirable to make a further physiological experiment on a small animal. For this purpose a quantity of residue or solution at least as great as that used for the tongue- test, and preferably several times as large, is made into one or more small pills with oatmeal, and given to a mouse or small bird by the mouth. It is distinctly preferable to operate in this manner rather than by hypodermic injection, in the case of such small medical assistance could be obtained. On analysis, an alkaloidal substance was isolated from the stomach, which gave exactly similar colour-reactions to the alkaloid extracted by the same means from the B.P. tincture of aconite. It produced a distinct tingling sensation on the tongue and lips, and charac- teristic symptoms in a mouse which had eaten a portion of the extract made into a pill with oatmeal. MANDRAGOKINE. 243 and sensitive animals as those which must almost necessarily be employed. If two healthy (white) mice be chosen, and one fed with ordinary oatmeal made into pills, and the other with oatmeal pills made with the alkaloidal extract, the symptoms may be readily compared, and several objections obviated. According to W y n t e r B 1 y t h, a quantity of aconite extract sufficient to cause distinct numbness of the lips will kill a mouse or small bird if administered in this manner.^ J. H. Munro (Chem. News, xlv. 110) has described an experiment in which he poisoned a sparrow with O'l grain of aconite root. Death ensued within an hour. The con- tents of the gizzard were mixed with the little which remained in the crop, and the alkaloid isolated. The extract did not respond to the taste or any chemical test ; but the solution, when soaked up in bread-crumbs, and given to a torn -tit, killed the bird in two or three hours. ATROPINE AND ITS ALLIES. TROPElNES.^ A remarkable series of natural alkaloids exist in the plants of the family Solanacece, and have been named, according to the plants in which they have been found, hyoscyamine and hyoscine, from Hyoscyamus niger (henbane) and H. albus ; atropine and belladonnine, from Atropa belladonna (deadly nightshade) ; daturine, from Datura stramonium (thorn-apple) ; duboisine, from Duboisia myopordides ; scopolamine, from Scopolia japo- nica; mandragorine,^ from Mandragora vernalis, &c. All these ^T. Stevenson found -g-gV? grain of Morson's crystallised aconitine, hypodermically injected, fatal to a mouse in eighteen minutes. T. G. Wormley found Duquesnel's aconitine equally potent, -^-^ grain proving fatal to a mouse, after violent retching and convulsions, in thirty-two minutes. ^ The author is indebted to Mr A. W. Gerrard and Mr R. Wright for perusal and correction of this section. * Mandragorine, the alkaloid of the root of Mandragora vernalis, has been investigated by F. B. Ahrens (Annalen, ccli. 312; Ber., xxii. 2159 ; Jour. Sac. Chem. Ind., viii. 814, 915). The analysis best accords with the formula C17H27NO3, but does not exclude the possibility of C17H.3NO3 representing the true composition. As extracted by ammonia and ether- chloroform, the base is obtained as a very deliquescent, colourless, vitreous mass, melting at 77°-79°. The sulphate forms small, white deliquescent plates, and the hydrochloride deliquescent needles. The aurochloride forms golden-yellow plates or needles melting at 153°-155°. BHaPtClg crystallises from hot water in yellow tables, melting with decomposition at 193°-194°. The mercuro-chloride crystallises from water or alcohol in slightly soluble needles or tables, which melt at 160°-16l°. Mandragorine is precipitated by 244 NATURAL TROPEINES. bases are distinguished by a remarkable power of dilating the pupil, and hence are often termed the "mydriatic alkaloid s," though the effect of pupil-dilation, or mydriasis^ is not confined to the alkaloids of the Solaiiaceoe. More recent investigations have reduced the number of the bases supposed to exist in the Solanacece. Thus, it appears that the bases isolated from A. belladonna and D. stramonium were simply a mixture of atropine and hyoscyamine in varying proportions, and that hyoscyamine is converted into atropine with such facility in presence of a trace of alkali, that it is not improbable that atropine does not always pre-exist in belladonna (see page 250). Similarly, the alkaloid described as duboisine is apparently identical with hyoscyamine, or with a mixture of that base and hyoscine. Constitution of Atropine and its Allies. The three best-known of the natural tropeines, viz., atropine, hyoscyamine and hyoscine, are all isomeric, being expressed by the formula C^p^HggNOg. The associated bases belladonuine and atropamine differ from these by the elements of water, and are probably anhydro-bases (page 251). All these alkaloids are readily saponifiable, and traces of the products of their hydrolysis are therefore liable to pre-exist with them in the plant, or to be pro- duced during the process of isolation. The following table exhibits the leading properties of the natural tropeines : ^ — Base. Formula. Melting- Point, 'C. Specific Rotation. Form. Products of Saponification by Baryta. Acid. Base. Atropine, Hyoscyamine, Hyoscine, Belladonuine, Atropamine, . Scopolamine, . Benzoyl-pseudo- tropine, C17H23NO3 C17H23NO3 C17H23NO3 C17H21NO2 C17H21NO2 Ci7H2iN04 C17H19N02 114-5 108-5 Below 60 49 -f0°to-r-9 -21" ... +0' Inactive. Needles. Needles or prisms. Colourless Amorphous. Varnish. | Radiating crystals. Tropic acid. Tropic acid. Tropic acid. Isomers of tropic and atropic acids. Atropic acid. Benzoic acid. Tropine. Tropin e. Pseudotropine. Pseudotropine. Pseudotropme. Base melting at 110°. Pseudotropine. picric acid, phosphotungstic acid, and iodised potassium iodide, which last yields an oily period ide. Mandragorine and its salts produce mydriasis, whether introduced into the system or directly applied to the eye. ^ The pre-existence of atropamine and belladonnine in the plants is not absolutely estabhshed. HYDROLYSIS OF TROPEINES. 246 The natural tropeines are all easily saponified by treatment with acids or alkalies. By the latter (especially baryta) the hydrolysis results in the formation of tropic acid, or an isomer thereof,^ and tropine or pseudotropine, in accordance with the equation : — C„H23N03+H,0 = C,Hj,03+C8Hi5NO. Tropeme. Acid. Base. When the hydrolysis is efi'ected by an acid, especially con- centrated hydrochloric acid, the tropic acid loses the elements of water, and atropic acid, CgHgOg, results, and at a high tem- perature this is more or less changed into its polymers a- and j8-isatropic acid, C^gH^gOg. Such products also result from the saponification of the anhydro-bases belladonnine and atropamine by baryta. The preferable method of effecting the saponification of the tropeines is to heat the alkaloid with saturated baryta-water to 60° or 80° C. for a few hours. Carbon dioxide is next passed tlirough the liquid till a drop ceases to give a pink coloration with phenolphthalein. The liquid is then filtered, and the filtrate acidulated with hydrochloric acid and twice shaken with ether. The ether is separated, and on evaporation yields the acid product of the hydrolysis ; on treating the aqueous layer with caustic alkali in excess and agitating with ether the basic product is extracted, and may be recovered by separating and evaporating the ether. Tropic Acid, C6H5.CH(CH2.0H)C0.0H, has the constitution of a-phenyl-/3-hydroxy propionic acid. It crystallises from hot water in needles or slender prisms, and on the spontane- ous evaporation of its aqueous solution in tablets which melt at 117°- 118° C. Tropic acid is not volatile without decomposition. It has a slightly sour taste, dissolves in 40 parts of cold water, and is soluble in alcohol and ether. When heated with a dilute solution of potassium permanganate, tropic acid gives an odour of bitter-almond oil, and on further treatment, benzoic acid is pro- duced. Tropic acid has been prepared synthetically (Ber., xiii. 2041). Atropic Acid, CgH5.C(CH2).CO.OH, has the constitution of o-phenylacrylic acid. It is isomeric with cinnamic acid (Part I. page 30), from which it differs by its solubility in water ^ Except in the case of benzoyl-pseudotropine, which yields benzoic acid on hydrolysis. 246 TROPIC ACID. TROPINE. (1 in 692 at 19°), its lower melting-point, and in not being pre- cipitated by manganous salts from its neutral solutions. Atropic acid has been prepared synthetically, and may also be obtained by heating tropic acid with hydrochloric acid, or by the direct action of fuming hydrochloric acid at 120°, or boiling concentrated baryta-water, on atropine. It crystallises from hot water in needles, and from alcohol in tablets or monoclinic prisms, which melt at 106°— 107°, are volatile with steam, and boil with decomposition at about 267°. Atropic acid is very soluble in carbon disulphide. It is oxidised to benzoic acid by chromic acid mixture, and yields formic and phenylacetic acids when fused with caustic potash. Sodium -amalgam reduces it to a-phenyl- propionic acid. Bromine-water converts it into bromo- phenylpropionic acid. IsATROPic Acid, Ci8^i6^4' ^^ polymeric with atropic acid, CgHgOg, and is always formed together with that acid and tropic acid when atropine is heated with hydrochloric acid. Isatropic acid is always formed in small quantity when atropic acid is recrystallised from hot water, and more largely if the solution be boiled for some time. Several isomeric modifications of isatropic acid exist; the a-isairopic acid is almost exclusively formed when atropic acid is heated for many hours to 140°— 160° in a closed flask. It forms small warty crystals which melt at 237°, are very slightly soluble in water, and nearly insoluble in ether. It is not affected by sodium- amalgam or cold bromine-water. /B-isatropic acid is formed together with much of the a-modification when the aqueous solution of atropic acid is boiled, and crystallises on cooling in small quadratic tablets, which melt at 206°, and are converted at 220°— 225° into the a-acid. y- and (5-isatropic acids were obtained by Liebermann by the saponification of truxilline (cocamine), a base contained in some varieties of coca leaves. From their source he subsequently named them a- and ^8-truxillic acids (com- pare page 286). Tropins, Cfi^{C2S.4^.0B.)lii.CIL^ has the constitution of a tetrahydropyridine, C5H9N, in which two of the hydrogen atoms are replaced respectively by methyl and hydroxy ethyl. It is the basic product of the saponification of both atropine and hyoscyamine (see page 244). - Tropine crystallises from absolute ether in rhombic tablets, melting at 61°-62° and boiling at 229°. It is hygroscopic, and very easily soluble in water and alcohol, remaining as an oil on evaporating these solutions. Tropine is a strong tertiary base and forms salts which crystallise well. BgHgPtClg forms large, orange-red monoclinic prisms, easily soluble PSEUDOTROPINE. 247 in warm water, insoluble in alcohol, and melting with decomposition at 198°-200°. BHAuCl^ forms large yellow plates, melting with decomposition at 210°-212°. The picrate is a yellow precipitate, crystallising from hot water in yellow needles. On ignition with soda-lime or caustic baryta, tropine yields methylamine, water and t r o p i 1 i d e n e :— CgHigNO = CHgNHg + H2O + C^Hg. When heated with fuming hydrochloric acid to 180°, or with glacial acetic and strong sulphuric acid, it loses the elements of water and is converted into t r p i d i n e, (^^^{G^^^.CE.^, a liquid base boiling at 1 62°, smelling like conine, and interesting from its relation to anhydro-ecgonine (compare page 270). PsEUDOTROPiNE, CgH^gNO, is isomcric with tropine, and results from the hydrolysis of hyoscine, belladonnine and atropamine. It forms rhombohedral crystals, melting at 106° and boiling at 241° to 243°. It is less hygroscopic than tropine, but very soluble in water and chloroform, and somewhat sjjaringly in ether. BgHaPtClg forms small orange-red rhombic prisms, easily soluble in water. BHAuCl^ forms small crystals melting at 198°.^ By treating pseudotropine with strong hydrochloric or sulphuric acid, abase isomeric with tropidine has been obtained. Atropine. Daturine. Tropyl-tropine. C17H23NO3; or C5H7(C2H40.CO.CHC6H5.CH2.0H)N.CH8. Atropine is the characteristic alkaloid of Atropa belladonna or deadly nightshade, though it appears sometimes to be wholly or in great part replaced by its isomer hyoscyamine.^ It ^ The melting-point of the aurochloride is almost the only marked distinc- tion between the pseudotropine produced by the hydrolysis of hyoscine and the (possibly identical) pseudotropine described by Liebermann {Ber., xxiv. 2336), as resulting from the saponification of the henzoyl-pseudotropine discovered by Gieselin coca leaves from Java. After boiling this base with hydrochloric acid for some hours the benzoic acid formed was extracted with ether, and the acid liquid evaporated to dryness. The hydrochloride was decomposed by oxide of silver; or excess of strong caustic soda solution added, and the base extracted with ether. Pseudotropine thus obtained has a strong alkaline reaction, crystallises in beautiful needles, melts at 106°-107'', boils at 240°-241°, and is easily soluble in water, alcohol, and benzene; and is precipitated by petroleum spirit from the last solution. BHCl forms hygro- scopic needles, the solution of which is precipitated white by mercuric chloride. BH^PtClg does not crystallise till the solution is evaporated nearly to dryness, but is then difficult to redissoTve in water, and is precipitated on adding alcohol. BHAUCI4 forms beautiful yellow needles, melting at 225°, and easily soluble in hot water and alcohol. The picrate forms easily soluble, yellow needles. 2 See an interesting paper by S c h ii t t e, Pharm. Jour. , [3], xxii. 429 (from Archiv, October 30th. 1891, page 492). 248 ATROPINE. also occurs in the seeds of Datura stramonium or thorn-apple, whence its name daturine.-^ Atropine has been prepared syntheti- cally by heating together at 100°, with dilute hydrochloric acid, the tropic acid and tropine resulting from the hydrolysis of hyoscyamine (page 244). The direct conversion of hyoscyamine into atropine has also been efifected (page 250), though the reverse change does not appear to have been realised. Pure atropine forms tufts or groups of colourless or white lustrous needles, or acicular prisms. In commerce it often occurs as a crystalline or nearly amorphous yellowish powder. By pro- longed exposure to air it gradually acquires a yellowish or darker tint. It melts when pure at 114° C. according to Ladenburg, or at 115°— 115°'5 according to Schmidt; but the commercial alkaloid often begins to melt at about 104°, and is entirely melted at 1 13°.^ At a higher temperature atropine shows signs of volatility, and, according to Dragendorff, volatilises slightly with steam, and even with alcohol-vapour. When dry, however, atropine does not lose weight by exposure to 100° C. Atropine is odourless, but has a disagreeable bitter and acrid taste. It is a powerful poison, producing delirium and convulsions (page 261). From 0'05 to 0*2 gramme is commonly fatal, and 0*001 gramme the maximum medical dose for an adult. Much smaller amounts than this produce marked mydriasis or dilation of the pupil when applied to the eye (page 255). Atropine is soluble in 600 parts of cold or 35 of boiling water; or, according to other authority, in 200 parts of cold and 54 of ^ For the preparation of atropine from belladonna, tlie dried leaves should be macerated for several days in cold water, the liquid concentrated by evapora- tion, treated with sodium carbonate, and agitated with benzene. The benzene solution is separated and agitated with dilute sulphuric acid, and the acid liquid again rendered alkaline with sodium carbonate, and the liberated alkaloid extracted with chloroform, the solution in which, when mixed with petro- leum spirit and allowed to evaporate spontaneously, deposits the atropine first, while the associated alkaloids remain in the mother-liquid. It is, perhaps, more easy to prepare atropine from belladonna root. Chloroform is the best solvent for the extraction of atropine from an alkaline liquid, but ether is pre- ferable for its subsequent purification and crystallisation (A. W. G e r r a r d). ^ In a private communication to the author, A. W. Gerrard states that pure atropine melts at 114°-115°. If some of the same sample be placed in water it melts at 83°-84°. This result is evidently due to hydration, for the substance, after contact Avith water, melts at the same temperature in a capil- lary tube ; but by exposure over strong sulphuric acid the alkaloid loses its water, and then again melts at 114°-115°. Operating on the same specimen of atropine as Gerrard, the author observed a melting-point of 114°*5, when a fragment of the substance was heated on the surface of mercury contained in a test-tube immersed in a bath of paraffin. SALTS OF ATROPINE. 249 boiling water. The aqueous solution undergoes rapid change in contact with air, becoming yellow and acquiring a disagreeable smell, but without losing its toxic character. Atropine dissolves in glycerin, and is readily soluble in alcohol, ether (60 parts), chloroform (3 parts), amylic alcohol and benzene (42 parts), but is only slightly soluble in petroleum spirit or carbon disulphide. The solutions are optically inactive, or very feebly Isevo-rotatory. The aqueous solution of atropine exhibits a distinct alkaline reaction to litmus, and also reddens phenolphthalein, the latter character distinguishing atropine and its isomers from almost all other known alkaloids (page 256). Other reactions of atropine are described on page 254, et seq. By treatment with alkalies or mineral acids, atropine readily under- goes saponification (page 245), but is not altered by boiling with strong tartaric acid (compare page 206). By strong nitric acid it is converted into a n h y d r o-a t r o p i n e (page 251). Atropine Sulphate, BgllgSO^, prepared by neutralising atropine with dilute sulphuric acid and evaporating the solution to dryness at 100°, is colourless and odourless, neutral, easily soluble in water and alcohol, but less readily in ether. The commercial salt is usually faintly alkaline, and keeps better when so made. The aqueous solution should be neutral or faintly alkaline to litmus. According to E. Schmidt, the more hyoscyaniine a sample of commercial atropine sulphate contains the finer is its crystalline appearance, the pure salt occurring as granular white masses. The absence of hyoscyamine is shown by the solution of the sample being optically inactive. Atropine borate and valerate are employed in ophthalmic surgery. Commercial Atropine and its Salts should be free from yellow colour, and should not become coloured on treatment with strong sulphuric acid or excess of ammonia. The substance should leave no appreciable residue on gentle ignition. A drop of a solution in 1000 parts of water should have an acrid and bitter taste, and yield a non-lustrous golden-yellow precipitate with a drop of auric chloride, which melts under boiling water. One drop of a solution of atropine in 45,000 parts of water (or less than 2 grains per gallon), when placed in the human eye, should cause dilation of the pupil in from forty to sixty minutes. Hyoscyamine. Daturine. Duboisine. C17H23NO3. This base occurs in belladonna, stramonium, and other solan- aceous plants in association with atropine,^ with which alkaloid it ^ Hyoscyamine occurs in the seeds, leaves, and roots of henbane and other «pecies of Hyoscyamus, in association with hyoscine. It accompanies atropine 250 HYOSCYAMINE — HYOSCINE. is isomeric; indeed Ladenburg {Ber., xxi. 3065) holds that atropine is an optically inactive base, standing to the active hyos- cyamine in the same relation as racemic acid stands to Isevo-tartaric acid. At any rate, by keeping hyoscyamine at a temperature slightly above its melting-point the optical activity gradually falls, and the product is found to consist of atropine.^ Conversion of hyoscyamine into atropine also occurs when its cold alcoholic solu- tion is allowed to stand after a slight addition of caustic potash or soda, or even of ammonia; but as the specific rotation of the product never falls below — 1° "9, whereas pure atropine is wholly inactive, it appears probable that the transformation is incomplete.^ Hyoscyamine forms slender colourless needles, which sometimes radiate in groups. In its solubilities and general chemical charac- ters it presents a close resemblance to atropine, which it also simulates in its physiological effects. The distinctions between the bases arc given on page 254. Hyoscyamine Sulphate, BgHgSO^, forms small golden-yellow or yellowish white crystalline scales, or a yellowish white amorphous powder, melting at 260° and deliquescing on exposure to air. Hyoscine, C17H23NO3. (See also page 244.) Hyoscine occurs, together with hyoscy- amine, in the leaves and seeds of Hyoscyamus niger (henbane). The " amorphous hyoscyamine " of commerce appears in many cases to consist chiefly of hyoscine. Hyoscine should be carefully difi'erentiated from atropine and hyoscyamine, as its mydriatic effects appear to be more rapid and powerful than those produced by the latter bases ] and, taken internally in doses of -^ grain, it produces eff'ects distinct from those of atropine.^ Free hyoscine forms a thick syrup, having a close general in Atropa belladonna (deadly nightshade), in which it is sometimes present to the exclusion of atropine, which, according to W i 1 1, is not un frequently formed from the hyoscyamine during the process of isolation. Hyoscyamine also occurs in association with atropine in the seeds of Datura strarnonium (thorn-apple) ; Avith hyoscine in the root of Scopoliajaponica and S. atropoides; and almost alone in the root of S. camiolica and the leaves and twigs of Duboisia myoporotdes. According as commercial hyoscyamine has been prepared from one or other of the above sources, it is liable to contain more or less of the associated alkaloids. ^ E. Schmidt {Pharm. Zeit., 1889, page 583) has obtained some indica- tion of the formation of another alkaloid besides atropine in this reaction. 2 Schiitte has recently found {Pharm. Jour. , [3], xxii. 429), that conversion into atropine occurs when hyoscyamine is kept long in solution or in the form of aurochloride, or is repeatedly crystallised from acidulated water. ' The calmative and sedative effects of henbane, which distinguish it in physiological action from belladonna and stramonium, are undoubtedly due to the predominating alkaloid, hyoscine. APO-ATROPINE— SCOPOLAMINE. 251 resemblance to hyoscy amine and atropine, but yielding pseudo- tr opine instead of tropine on saponification (page 247). The reverse reaction has not been realised. Other characters of hyoscine, and distinctions from hyoscyamine and atropine, are given on page 254. Hyosdne Hydrohromide should occur in colourless rhombic crystals, losing 12 "3 per cent, of their weight when dried at 100°. With Yitali's test (page 257) it should give a violet coloration. Commercial hyoscine hydrohromide is liable to contain a large proportion of the corresponding salt of scopolamine, and, according to E. S c h m i d t, often essentially consists of this salt.^ BHI forms pale golden prisms, the solution of which is Isevo- rotatory. BHAuCl^ crystallises in prisms, melts at 200°, and is sparingly soluble in water. Anhydro-Tropeines. Apo-atropine, Cii^Hgj^NOg, preferably called anhydro-atropine, difi'ers from atropine by the elements of water, and hence is isomeric with atropamine and belladonnine. It is obtained by gradually adding atropine to fuming nitric acid maintained at about 50° C. On rendering the liquid alkaline and extracting with ether, the new base is dissolved, and is obtained on evaporating the solvent as an oil, or prisms melting at 60°-62°, slightly soluble in water, but readily in chloroform. Apoatropine is not mydriatic or irritat- ing to the eye, and apparently not poisonous. It yields a crystalline sulphate, sparingly soluble in cold water. The chloroplatinate is crystalline, and, unlike that of atropine, only sparingly soluble in hydrochloric acid. The aurochloride is amorphous, and melts at 180°. Anhydroatropine is hydrolysed by boiling baryta-water, forming tropine and atropic acid. Atropamine, Cj^jrHgiNOg (page 244), is not a constant con- stituent of belladonna, and, owing to the readiness with which it undergoes change, it is liable to escape recognition. It was ^ Scopolamine, or Scopoleine, C17H21NO4, was first found in the root of S. atropoides, and has since been isolated in small quantities from belladonna root, stramonium seeds, and D. myoporo'ides. In one case the mydriatic alkaloid of the last-named plant consisted essentially of scopolamine, while the base from another sample of the leaves was essentially hyoscyamine. Scopol- amine appears to contain a hydroxyl-group, as it fornxs an acetyl-derivative, while towards nitrous acid it behaves as a tertiary base. By boiling with baryta it is hydrolysed with formation of atropic acid and a crystalline base melting at 110° C. Scopolamine hydrohromide forms large glassy crystals. The aurochloride forms long shining needles, presenting a peculiar comb-like or serrated appearance at the margin. When anhydrous, the aurochloride melts at 214°, and is nearly insoluble in water. 252 . ATROPAMINE. BELLADONNINE. isolated by Hesse (Annalen, cclxi. 87) by dissolving in acetic acid the alkaloids left in the mother-liquor after the preparation of atropine, and adding common salt to the solution until a milky turbidity was produced. On standing, the hydrochloride crystallises out, and can be obtained pure by recry stall isation from boiling water after treatment with animal charcoal. On treating the hydrochloride with dilute ammonia and ether, the atropamine dissolves, and may be obtained as a soft colourless varnish on evaporation. At 60° it forms a colourless, odourless liquid, which does not lose weight at 100°. It is only sparingly soluble in water and petroleum ether, but very readily in alcohol, ether, chloroform and benzene. The alcoholic solution is optically inactive, has a bitter taste, does not redden phenolphthalein (distinctive from atropine), but colours red litmus-paper blue and neutralises acids. Atropamine possesses no mydriatic properties, but produces a burning sensation and inllammation when dropped into the eye, whereas apo-atropine is inactive. Atropamine is considered by Hesse to bear the same relation to hyoscine that anhydro-atropine bears to its parent-base, and is isomeric with belladonnine, from which it differs in ready crystal- lisability of its hydrochloride and hydrobromide, a fact which affords a ready means of separating it from the other alkaloids of belladonna. If the hydrochloride or hydrobromide of atropamine be moistened with a mineral acid, and warmed or exposed to sun- light, the base is readily converted into belladonnine. Atropamine is also transformed into belladonnine by solution in cold concentrated sulphuric acid, or by the mere evaporation of the solution of its sulphate. Dilute sulphuric acid also effects the con- version, but a preferable plan is to heat atropamine with moderately concentrated hydrochloric acid to about 80°. If the solution be boiled, or if baryta-water be employed as the converting agent, the belladonnine first formed undergoes hydrolysis, so that atropamine and belladonnine ultimately yield the same saponification products. Belladonnine, Ci^Hg^NOg (page 244), is isomeric with anhydro- atropine and atropamine.^ Its formation from the latter substance is described above. Belladonnine forms a varnish-like mass, very sparingly soluble in water, but readily in alcohol, ether, chloro- form and benzene. The salts are amorphous. BgHgPtClg and BHAuCl^ are yellow pulverulent precipitates, quite insoluble in cold water. Crude belladonnine is said to contain oxytropiney CgHj^^NOg, a crystallisable base melting at 242°. When belladonnine is boiled with baryta-water, or moderately * According to Ladenburg the formula of belladonnine is C17H23NO4, and it is converted by hydrolysis into tropic acid and oxytropine. HOMATROPINE. 253 concentrated hydrochloric acid, it is hydrolysed with formation of pseudotropine, CgHj^NO, and two acids of the formula CgHj^Og and CgHgOg ; but as both these bodies are amorphous they appear to be isomeric, and not identical with tropic and atropic acids respectively. When atropamine or belladonnine is heated at 100° with fuming hydrochloric acid, pseudotropine and crystallisable atropic acid are formed, instead of the fore- going amorphous acids. Artificial Tropeines. When tropine (page 246) is treated with benzoyl chloride it yields benzoyl-tr opine, C^lI>j{C2H.^.0Bz)^.CIi^, which is the type of a series of bodies called tropeines (Ladenburg), having the constitution of esters of tropine. The natural mydriatic alkaloids belong to this class, and atropine has actually been obtained synthetically by heating tropine with tropic acid. Bbnzoyl-tropine, C5H7(C2H^.0C7H50)NCH3, is a crystallisable substance which forms salts very similar to those of atropine. It is a powerful local anaesthetic, and when applied to the eyes produces the dilation characteristic of the natural tropeines. Benzoyl-pseudo- tr opine occurs naturally in certain coca leaves from Java (page 287). Salicyl-tropine, C^^{C^^.0.C^11^0^^CHz, is obtained by evaporating to dryness a mixture of salicylic acid and atropine with dilute hydrochloric acid. It is a weak poison, devoid of action on the pupil. HoMATROPiNE, C^gHgiNOg, is an artificial base having the con- stitution of a lower homologue of atropine. It is prepared by evaporating a mixture of tropine (from the saponification of hyoscyamine) and mandelic acid, with dilute hydrochloric acid. Mandelic acid itself is produced by the action of hydrochloric acid on amygdalin, the glucoside of almonds. It is the lower homologue of tropic acid, and has the constitution of a phenyl- glycollic acid: — Mandelic acid. Tropic acid. Homatropine crystallises from absolute ether in prisms which melt at 98° C. It is very deliquescent, and hence is usually obtained as a syrup. It dissolves sparingly in water, but freely in ether and chloroform. Homatropine behaves like atropine with Gerrard's test, but with Yitali's test (page 257) it yields a yellow instead of a violet coloration. With Mayer's reagent the salts yield a white, curdy 254 REACTIONS OF TROPEINES. precipitate, and with picric acid a yellow precipitate soon becoming crystalline. Homatropine resembles atropine in its general physiological effects, but is less toxic, and in small doses is a true hypnotic. It dilates the pupil as powerfully as atropine, but the effect sub- sides far more rapidly, and hence the base has proved valuable in ophthalmic surgery. Homatropine Sulphate crystallises in silky needles. The hydro- chloride is crystallisable and very soluble. The chloroplatinate is deposited from concentrated solutions in fine crystals. BHAuCl^ is described on next page. HomMropine Hydrohromide, CjgHgiNOg, HBr, crystallises in non- deliquescent, fiat rhombic prisms or plates which form wart-like aggregations. According to the British Pharmacopoeia (Additions, 1890) it is a white crystalline powder or aggregation of minute pris- matic crystals, soluble in 6 parts of cold water and 133 of alcohol.^ Detection and Determination of Tropeines. Atropine and the allied bases present a close general resemblance, alike in their physical, physiological, and chemical characters. The following table shows the principal distinctions between them : — Atropine. Hyoscyamine. Hyoscine. Appearance, Melting-point, " C. Optical activity, Keaction of free base with alco- holic mercuric chloride (page 256), Characters of mer- curochloride, Characters of platinochloride, Characters of aurocliloride, Basic product of saponification, Needles or acicular prisms. 114-5 Inactive or feebly leevo- rotatory. Ked precipitate. Gummy precipitate. Not ppted. from 5 per cent, solutions. On evaporation, forms monoclinic crystals, melting at 207'. Lustreless ; yellow, melts at ISS'-ISS'. Tropine, melting at 61°-62°. Slender, radiating needles or crystal- line powder. 108-5 Sd= -21°, in alcoholic solution. Yellow or red precipi- tate. Oil, solidifying to plates. Not ppted. from 5 per cent, solutions. On evaporation, forms beautiful triclinic crystals, melting at 200°. Lustrous, golden-yel- low scales, melting at 160°-162°. Tropine, melting at 61°-62°. Syrup. White precipi- tate. Amorphous or oily. Small octohedra soluble in water, alcohol and ether-alco- hol. Yellow prisms, melting at 198°- 200°. Pseudotropine, melting at 106*. •^ " If 2 minims of chloroform be shaken with 10 minims of a 10 per cent, aqueous solution, and chlorine- water be cautiously added, the chloroform will assume a brownish colour. A 2 per cent, aqueous solution is not precipitated AUROCHLORIDES OF TROPEINES. 266 The reactions of the tropeines with auric chloride form the best distinctions between them. Atropine aurochloride is thrown down from dilute solutions as an amorphous or oily precipitate which gradually becomes crystalline. Under the microscope it appears in rosettes and other very characteristic forms. It melts under hot water, and is deposited from its solution in boiling water acidu- lated with hydrochloric acid in minute crystals, which are lustreless after drying, and melt at 135°- 138°. Hyoscyamine aurochloride is precipitated in brilliant, irregular, golden-yellow scales, appearing under the microscope in quadratic forms. It retains its lustre when dry, and melts at 160°— 162°. Hyoscine aurochloride cTjstal- lises in yellow prisms which melt at 198°-200°, and are less soluble and less lustrous than the hyoscyamine salt. Homatropine aurochloride is at first oily, but soon crystallises in prismatic forms. Sco2^olamine aurochloride is described on page 251. Ladenburg employs the aurochlorides to separate the tropeines from each other. The atropine salt is the most insoluble and in fractional precipitation is thrown down first, while the hyoscyamine salt is the most readily soluble. The alkaloids may be recovered by decomposing the aurochlorides with sulphuretted hydrogen, adding ammonia to the filtrate, and agitating with chloroform or ether. The foregoing properties and reactions are almost the only ones afifording fairly sharp distinctions between atropine and its isomers. The following reactions are (when not otherwise stated) common to the three bases, and distinguish them from other alkaloids. a. By far the most delicate test for the tropeines is their power of producing rtiydriasis or dilation of the pupil of the eye. Dilation from the application of a solution weaker than 1 in 500 causes little inconvenience to the human eye, but solutions far weaker produce the effect quite distinctly, and even powerfully, and the eye of a young cat, dog, or rabbit is to be preferred. In making such an experiment, an aqueous solution must be prepared either of the free alkaloid or its sulphate or acetate. The solutions by the cautious addition of a solution of ammonia previously diluted with twice its volume of water. About a tenth of a grain moistened with 2 minims of nitric acid, and evaporated to dryness on the water-bath, yields a residue which is coloured yellow by an alcoholic solution of potash. If about a tenth of a grain be dissolved in a little water, and the solution be made alkaline with ammonia and shaken with chloroform, the separated chloroform will leave on evaporation a residue which will turn yellow, and finally brick-red, when wanned with about 15 minims of a solution of 2 grains of perchloride of mer- cury in 100 minims of proof spirit." — British Fharmacopceia (Additions, 1890). 256 REACTIONS OF TKOPEINES. should be neutral or only feebly alkaline, not strongly contami- nated even with neutral salts, and not alcoholic. A drop or two of such a solution is placed by means of a pipette or glass rod on one of the eyes, and the size of the pupil compared with that of the fellow-eye from time to time. E. R. Squibb {Ephemeris, ii. 855) states that distinct mydriasis is produced by a solution of 0"000000427 gramme of atropine sulphate in less than an hour. Such an intense effect is quite peculiar to atropine and its isomers (hyoscine is even more powerfully mydriatic), but more or less dilation of the pupil is also produced by cocaine and preparations of hemlock (conine) and digitahs. Aconitine has a variable effect, and nicotine is said first to dilate and then to contract the pupil. Certain ptomaines exert a mydriatic effect. b. Free atropine, as obtained by evaporating its chloroformic or ethereal solution (after liberation of the alkaloid from one of its salts by ammonia), gives a red colour with phenolphthalein. This reaction is common to hyoscyamine and hyoscine, and is also pro- duced by the artificial base homatropine, but is not given by any other alkaloid in common use (except, according to P 1 u g g e, the volatile bases conine and nicotine). Fliickiger, who first observed the peculiar behaviour of the tropeines with phenol- phthalein (Pliarm. Jour., [3], xvi. 601), recommends that a minute quantity of the alkaloid to be tested should be placed on phenol- phthalein paper, which is then wetted with strong alcohol. I^o coloration will be produced at first, but on allowing the alcohol to evaporate, and touching the alkaloid with a drop of water, a bril- liant red coloration will appear. On adding alcohol the colour is destroyed, but appears again as the spirit evaporates.^ c. When a solution of mercuric chloride in proof-spirit is cautiously added to free atropine (as obtained by evaporation of a chloroform solution after liberation of the alkaloid by ammonia), avoiding excess, a red precipitate is produced. A. W. G e r r a r d, who first described this reaction {Fharm. Jour., [3],xiv. 718), states that the precipitate consists of mercuric oxide (with a trace of mercurous oxide), and expresses the reaction by the following equation:— 2 Ci^Hgs^^Og -f HgClg + H^O = HgO -|- 2Ci7H23]S^03,HCl. The atropine hydrochloride reacts with an additional quantity of mercuric chloride to form the double chloride BHCl,2HgCl2, which separates in crystalline tufts when the liquid is allowed to stand for a few hours. In a more recent paper {Pharm. Jour., [3], xxi. 898) Gerrard has modified and more precisely defined the method of making the test as follows :— 0*1 grain of the free alkaloid ^ This behaviour is peculiar. Caustic alkalies react perfectly with phenol phthalein in alcoholic solution. gereard's test for atropine. 257 (extracted from a salt by ammonia and chloroform) is placed on a watch-glass or in a test-tube, and 20 minims of a 2 per cent, solution of mercuric chloride in proof-spirit gradually added. A red coloration is yielded at once by atropine. Hyoscyamine at first becomes yellow, then darkens a little, and finally, on heating, a well-marked red precipitate is formed. If a large excess of hyoscy- amine be used, merely a yellow precipitate is formed, while with a large excess of the reagent no precipitation occurs.^ Homatropine (page 253) also yields a red precipitate under the conditions of the test ; but hyosdne gives neither a red nor a yellow coloration or precipitate, and hence is sharply distinguished from the other tropeines. Gerrard found no red or yellow precipitate to be pro- duced by strychnine, brucine, morphine, codeine, veratrine, aconi- tine, conine, gelsemine, caffeine, cinchonine, cinchonidine, quinine or quinidine ; though most of these bodies gave white precipitates, which in the cases of codeine and morphine became pale yellow on heating. This behaviour has been confirmed bySchweissinger (Arch. Pharju., [3], xxii. 827), who also states that cocaine gives a white precipitate (only appearing in strong solutions and soluble on warming) and scoparine a yellow precipitate with mercuric chloride ; while strychnine, caffeine, arbutine, sparteine and condurangine are stated to yield no reaction. Schweissinger suggests that the test might be made quantitative for atropine by determining the mercuric oxide precipitated ; but this would only be possible in the absence of alkaloids or other substances giving precipitates of any kind with mercuric chloride. The value of Gerrard's test has also been confirmed by FlUckiger {Pharm. Jour., [3], xvi. 601), who found cocaine to give a pure white precipitate which very soon turned red. d. Gerrard has also observed {Pharm. Jour., [3], xvi. 762) the liberation of m e r c u r o u s oxide from calomel and other mercurous salts by the action of atropine. If atropine be dissolved in alcohol, and four measures of water added, the solution will immediately precipitate black mercurous oxide from a solution of mercurous nitrate free from excess of acid. This is best prepared by adding caustic soda, drop by drop, to a solution of mercurous nitrate until a slight permanent precipitate is produced, and then filtering. e. D. V i t a 1 i has observed that if a minute quantity of solid atropine be treated with a drop of fuming nitric acid, the liquid ^ Harnack {Chcm. ZeiL, xi, 52) disputes the identity of hyoscyamine and duboisine, and states that the former gives a clear solution witli Gerrard's veagent, a slight turbidity appearing on continued heating, while duboisine gives a white turbidity immediately, and on warming a white precipitate. VOL. III. PART II. R 258 VITALI'S TEST. evaporated at 100°, and the residue when cool touched with a drop of a freshly-prepared solution of caustic potash in absolute alcohol, a magnificent violet coloration is produced, which slowly changes to dark red and ultimately disappears, but can be repro- duced by adding more alcoholic potash. The violet reaction is almost jieculiar to atropine and its isomers, and is said to be produced by O'OOOl milligramme of the alkaloid. Out of some sixty alkaloids examined no others were found to give a violet coloration.. The coloration is not produced if aqueous potash be substituted for the alcoholic solution. Strychnine gives a red, brucine a greenish, and homatropine a yellow colour when simi- larly treated. Arnold {Arch. Pharm., 1882, page 564) modifies the test by moistening the alkaloid with strong, cold sulphuric acid, and then adding a fragment of sodium nitrite. With atropine a yellow colour is produced, which, on applying alcoholic potash, changes to reddish violet and then to pale rose. Strychnine gives an orange-red colour, but homatropine behaves like atropine. Alkaloids which yield strong colorations before the application of the alcoholic potash (e.g., morphine, narcotine, narceine) render the test inapplicable. Fluckiger (Pharm. Jour., [3], xvi. 601) recommends that 1 milligramme of atropine and about the same quantity of sodium nitrate should be rubbed together with a glass rod, the end of which has been moistened with a very little con- centrated sulphuric acid. A saturated solution of caustic soda in absolute alcohol is then added drop by drop ; when in presence of atropine a red or violet colour will be produced. When sodium nitrite is substituted for the nitrate in the above test, an orange mixture is obtained, which, on dilution with a strong aqueous solu- tion of caustic soda, turns in succession to red, violet and lilac. E. Beckmann {Arch. Pharm., [3], xxiv. 481) has pointed out that veratrine behaves somev/hat similarly to atropine with Vitali's test ; but states that with nitrous acid or a nitrite instead of nitric acid, and aqueous instead of alcoholic potash, atropine gives a reddish violet coloration, and veratrine a yellow one. /. When atropine is heated to the boiling-point with a mixture of equal measures of glacial acetic and strong sulphuric acids no coloration is produced ; but after a time the liquid exhibits a well- marked yellowish or brownish green fluorescence. After cooling, the liquid has a pleasant aromatic odour in addition to that of acetic acid. The behaviour of other tropeines with this test, which is due to E. Beckmann, does not appear to have been recorded. Veratrine gives a similar brownish fluorescent liquid, but during the previous heating the solution acquires an intense cherry-red colour. g. According to A. W y n t e r B 1 y t h, if a particle of atropine be REACTIONS OF TROPEINES. 259 treated with a few drops of concentrated baryta solution, the liquid evaporated to dryness, and the residue strongly heated, an agreeable odour resembling that of hawthorn-blossom will be perceived. h. According to the German Pharmacopoeia, if at least 0*001 gramme of atropine sulphate be heated in a small test-tube until white vapours appear, and 1"5 gramme ( = 0'8 c.c.) of sulphuric acid be then added, and the heating continued until the mixture begins to turn brown, on then adding 2 c.c. of water an agreeable odour will be perceived ; and on further adding a crystal of potassium permanganate, the odour of bitter-almond oil will be obtained. i. A saturated solution of bromine in hydrobromic acid ^ gives with atropine and its salts, even in very dilute solutions (1 : 10,000), a yellow amorphous precipitate, which in a short time becomes crystalline. The precipitate from somewhat strong solutions of the alkaloid disappears after a time, but is immediately reproduced on adding more of the reagent. The precipitate is insoluble in acetic acid, and only very sparingly soluble in a large excess of the mineral acids or fixed caustic alkalies. It is even produced from a solution of atropine in concentrated sulphuric acid. The microscopic appearance of the precipitate is highly characteristic, exhibiting under a magnifying power of 75 to 125 diameters lanceolate, leaf-like crystals, grouped together like the petals of a flower. These forms may be obtained by the spontaneous evapora- tion of a drop of liquid containing only ^3^0^ grain of atropine. If not produced, a drop of water should be added, and evaporation repeated. T. G. W r m 1 e y, who is the observer of the reaction, considers the formation of the crystals quite characteristic of atropine or hyoscyamin^-. Most alkaloids give yellow precipitates with Wormley's reagent, but all these deposits, except those pro- duced by atropine, hyoscyamine and meconin, remain amorphous ; and that produced by the last-named substance has quite a different microscopic appearance from those formed by the mydriatic alkaloids. The behaviour of hyoscine with Wormley's reagent has not been, recorded. ./. A solution of iodine in iodide of potassium throws down, from solutions of atropine, hyoscyamine and hyoscine, acidulated with hydrochloric acid, the whole of the alkaloid as a reddish brown or dark green amorphous precipitate of the tri-iodide, insoluble in acetic acid, but somewhat affected by other acids. Dunstan and Ransom (Pharm. Jour., [3], xiv. 625) recommend the reagent for ^ Wormley states that in tlie absence of liydrobroniic acid, a solution of bromine in alcohol may be used. A solution in hydrochloric acid would appear preferable. 260 REACTIONS OF TROPEINES. the purification and determination of atropine and its isomers. For this purpose they dissolve the alkaloid in dilute hydrochloric acid, and add excess of a strong solution of iodine in potassium iodide. The precipitate at once agglomerates, and is filtered off", slightly washed with the solution of iodine, and then decomposed by pouring on the filter a solution of sodium thiosulphate, which dissolves it to a colourless h'quid, from which the alkaloid is recovered by addition of ammonia and agitation with chloroform. k. Mayer's reagent precipitates atropine and its isomers from solutions not too dilute, and has been employed with limiteil success for their quantitative determination. The characters of the precipitate and the best method of operating have already been fully described (page 140 et seq.). I. Potassio-iodide of bismuth and potassio-iodide of cadmium precipitate atropine from highly dilute solutions. Their reactions with the isomeric alkaloids have not been recorded. m. Phosphomolybdic and phosphotungstic acids precipitate atropine and its isomers from somewhat dilute solutions, and are of service for concentrating the alkaloids and separating them from other organic matter. n. Am alcoholic solution of picric acid yields a yellow amorphous precipitate in solutions of atropine which are not too dilute. The precipitate becomes crystalline after a time, and appears under the microscope in highly characteristic forms. With hyoscyamine, picric acid yields an oily precipitate, rapidly solidifying to right- angled laminae, very similar to those formed by atropine picrate. The reactions of atropine and its isomers with other reagents are not characteristic. Potassium iodide, thiocyanate, ferrocyanide, ferricyanide and chromate fail to precipitate even concentrated solutions of these alkaloids. Atropine and its allies are not removed from acidulated solutions by agitation with immiscible solvents. From solutions rendered alkaline by ammonia, or an alkali-metal carbonate, they are readily and completely extracted by chloroform, and with less facility by ether. The separated solution may be evaporated, and the residue dried without loss at 100°. The bases thus isolated are distin- guished from all other well-known alkaloids by their power of reddening phenolphthalein (test h), and (with the exception of hyoscine) giving a red precipitate when warmed with an alcoholic solution of mercuric chloride (test c). The alkaloidal residue may be titrated with standard hydrochloric acid, using litmus or methyl- orange as an indicator, and further purified, if desired, by con- verting the resultant hydrochlorides into the tri-iodides (test e), and recovering the alkaloids from the precipitates. POISONING BY ATROPINE. 261 TOXICOLOGICAL DETECTION OF ATROPINE AND ITS AlLIES. Atropine, hyoscyamine and hyoscine are all higlily poisonous. Cases of poisoning by the pure alkaloids are rare, but both criminal and accidental poisoning by the plants of which they are the active principles have been frequent ; and, in India, poisoning by stramonium has achieved the position of a profession. The symptoms of poisoning by atropine and its isomers are thus described by A. Swaine Taylor : — Heat and dryness of the mouth and throat, nausea, vomiting, giddiness, indistinct or double vision, delirium, great excitement and restlessness, convulsions followed by drowsiness, stupor, and lethargy.^ The pupils are much dilated and the eyes insensible to light. Occasionally the pupils are contracted during sleep, although dilated in the waking state. The symptoms often come on very soon after taking the poison, while recovery may be delayed for several days, or even weeks. The symptoms of poisoning by stramonium are very similar to those produced by belladonna and hyoscyamus, but more severe. Ringing in the ears, dryness of the throat, and flushed face are early symptoms. Delirium of a violent kind, with spectral illusions, comes on rapidly, and the pupils are widely dilated. There is often paralysis of the lower extremities. The post-mortem indications of poisoning by atropine and its isomers are not characteristic, except that the pupils are dilated. The brain and its membranes are found congested. AYhere solid parts of a solanaceous plant have been eaten the fragments may often be found in the stomach, and identified by their botanical and microscopic characters. The detection of atropine and its isomers in cases of poisoning may be effected by the Stas-Otto process. Heating with alkalies or mineral acids must be avoided, or the alkaloid may undergo hydrolysis (page 245). Hence tartaric or acetic acid should be used to acidify the matters to be examined. Ammonia or a carbonate of alkali-metal should be used to liberate the alkaloid, and ether or (preferably) chloroform employed for its extraction. The tests most serviceable for the recognition of atropine and its isomers in cases of poisoning are : — 1. The dilation of the pupil (page 255). 2. The reactions of the free alkaloid, as obtained in the chloro- form-residue, with phenolphthalein and a spirituous solution of mercuric chloride. ^ The symptoms of atropine poisoning, especially in children, are not unlike those of scarlet fever. Some cases resemble rabies, and the garrulous delirium and hallucinations of an adult are very similar to those of delirium tremens. 262 CHRYSATROPIC ACID. 3. The reaction of a solution of the alkaloid with bromine (page 259), and the microscopic appearance of the precipitate. 4. The production of a violet colour by Vi tali's test (page 257). 5. The evolution of an agreeable odour when the alkaloid is evaporated to dryness with baryta-water, and the residue heated. 6. The microscopic appearance of the picrate. Atropine does not appear to suffer change in the body after death. It has been detected after a considerable interval of time. Ptomaines having a mydriatic action have been met with. Belladonna, Henbane, and Stramonium. Atropa belladonna or deadly nightshade,^ Hyoscyamns niger or henbcine,^ and Datura stramonium or thorn-apple ^ are the three chief sources of the tropeines ; but these or similar alkaloids are found in a number of allied species, and the poisonous alkaloid solanine occurs in all the species of Solanum, as well as in other members of the SoJanacece.^ In addition to the alkaloids, which are probably in combination with malic acid, belladonna root contains cellulose, starch, sugar, inulin, asparagin, fatty matter, a fluorescent substance,^ and 1 French, la Belladone, la Morelle furieuse ; German, TollkirscJie, Wolfs- kirsche, Tollkraut. 2 French, la Jusquiame; German, BilsenkratU. ^ French, Stramoine ; German, Stcchayfel. ^ A minute proportion of an alkaloid, apparently identical with hyoscyamine, has been found in lettuce by T, S. Dymon d {Troc. Cliem. Soc, 1891, p. 165). ^ The fluorescent substance contained in belladonna root, and present also in the leaves and stalk, is called by H. K u u z {Arch. PJMrm,, [3], xxiii. 722) chrysatropic acid, and is said to have the formula Cj.jHioOj. H. Paschkis {Arch. Pharm., [3], xxiii. 541 ; xxiv. 155) has isolated what is apparently the same body from the berries of ripe belladonna, and ascribes to it the formula C10H8O4. He considers it identical with the scopoletin obtained by Eykman from Scopolia japonica. It forms pale yellow, rhombic prisms or needles, melting at 198°-201°, and subliming without decomposition when care- fully heated. It dissolves in about 80 parts of hot water, more sparingly in cold water and ether, but readily in acetic acid, alcohol, chloroform, amylic alcohol and benzene. It is extracted by the last three solvents from its aqueous solution. The aqueous, alcoholic and ammoniacal solutions exhibit a splendid blue fluorescence when dilute, and emerald-green when concentrated. The fluorescence is destroyed by acids. Ferric chloride gives an emerald-green coloration changing to cobalt-blue. Fehling's solution and ammonio-nitrate of silver are reduced on warming. In moderately concentrated nitric acid the substance dissolves with yellow colour, changed to blood-red by ammonia. (This reaction resembles that of se s c u 1 i n, observed by Sonnenschein. ) Kunz isolated chrysatropic acid by treating the extract of belladonna with acid and agitating with ether. On evaporating the ether, and washing the Woody Roots. Soft Roots. 7-94 per cent. 10-28 percent. , 3-43 ,, 2-20 ., . 4-60 „ 3-68 „ . 22-53 „ 29-87 ,, . 15-96 „ 10-50 „ BELLADONNA. 263 a red colouring-matter called atrosin, which is also found in considerable quantity in the berries. The proportion of starch in young belladonna roots is considerable, but it is present only to a limited extent in older and more woody roots, and, according to W. Merz, is almost entirely absent during summer. The following analyses of air-dry belladonna roots are due to E. M. Holmes : — Moisture, Soluble ash, . Insoluble ash, Alcoholic extract, Aqueous extract, Belladonna leaves contain cellulose, chlorophyll, alkaloidal salts, fatty and resinous matters, &c. Choline is present, and, accordinc; to B i 1 1 z, asparagin sometimes crystallises from the extract after long keeping, but the crystals observed by A 1 1 f i e 1 d consisted of potassium nitrate and chloride. By dialysis, Attfield isolated potassium nitrate, and square prisms of an organic salt of magnesium. Kunz found O'G per cent, of succinic acid in an extract prepared from the herbaceous parts of belladonna. Fliickiger found the ash of dry belladonna leaves to amount to 1 4*5 per cent., and to consist chiefly of the carbonates of calcium and the alkali-metals. With regard to the alkaloids of belladonna, 0. Hesse {Annalen, cclxi. 87) states that in his experience the herb of cultivated belladonna contains atropine almost exclusively, but that it is associated with other" alkaloids in the leaves of wild plants, and especially in the roots of both kinds. In an old root, Hesse found much hyoscy amine but no atropine. E. Schmidt (Pharm. Zeit, 1889, page 583) found hyoscyamine but no atropine in full grown roots which had been kept for years. In roots of one year's growth he found both atropine and hyoscyamine, but the latter alkaloid only in fresh old root?. The leaves of wild belladonna contained much hyoscyamine and a little atropine, while the ripe berries contained atropine only. E. Schmidt has found both hyoscyamine and hyoscine in ScopoUa atropo'ides and Scopolia iaponica^^ and traces of an alkaloid having a mydriatic action in Solanum tuberosum, S. nir/rum and Lycium harbarum,. Mandra- gorine, the alkaloid of Mandrarjora vernalis, is mydriatic and possibly isomeric with atropine (page 243). , crystalline residue with cold ether, chrysatropic acid remained, while 1 e u c o- tropio acid, C17H32O6, dissolved. The latter is a bitter substance, crystal- lising in microscopic prisms which melt at 74°. ^ Dunstan and Chaston found the alkaloid of Scopolia cnrnioh'ca to consist of hyoscyamine with a possible trace of hyoscine. 264 BELLADONNA. A. W. Gerrard {Tear-Book Pharm., 1881, 1882, 1884) lias published a number of valuable observations on belladonna, in which he found the following percentages of alkaloid ; — Age of Plant. Two years, Three years, Four years, Wild Plant. Cultivated Plant. Root. Leaves. Root. Leaves. •260 •431 •207 •320 •381 •407 •370 •451 •410 •510 •313 •491 These and other observations of Gerrard show that the leaf of belladonna is the part of the plant richest in alkaloid ; the root, fruit, and stem coming next in the order stated.^ The results of A. B. Lyons {Mamial of Pharmaceutical Assaying) do not show the same distinction, for in twelve samples of (air-dried) leaves the proportion of alkaloids varied from 0*4 1 to 0*69 per cent., and in fifteen samples of roots from 0*47 to 1'35 per cent. The extractive matter in the leaves (air-dried, and treated with 66 per cent, alcohol) ranged from 6'6 to 12*1 per cent., and in the roots from 2 2 "5 to 31*5 per cent., with an average of about 8 per cent, of moisture. Lyons states that the pressed leaves do not suffer deterioration when kept for six years. R. Kordes found 0*58, and von Gunther '8 3 per cent. of alkaloid in belladonna leaves, while L e f o r t gives the average yield from 8 specimens at 0'436 per cent. As the general result of published investigations, Farr and "Wright state that the proportion of alkaloids in good specimens of commercial belladonna leaves ranges from 0*30 to 0*87 per cent., their own experiments varying between 0*30 and 0'90, with an average of 0'49 per cent. German leaves are distinctly poorer in alkaloid and extractive matter than those of English growth, and hence the B.P. direction to prepare the tincture from tl^e leaves of "plants grown in Britain" should be strictly observed. As one part of belladonna leaves produces 20 parts of the B.P, tincture, it follows that the proportion of alkaloid in this prepara- tion averages 0*025 per cent., which strength might advantageously be adopted as a standard. For the assay of belladonna root, D u n s t a n and Ransom (Pharm. Jour., [3], xiv. 623) recommend extraction in the 1 The influence of age on the proportion and nature of the alkaloids of belladonna has also been studied by Schiitte {Pharm. Jour., [3], xxii. 429). ASSAY OF BELLADONNA. 266 following manner: — 20 grammes of the dry and finely-powdered root is extracted by hot percolation with a mixture of equal volumes of chloroform and absolute alcohol.^ If an extraction- apparatus be used about 60 c.c. of the mixture will be required. The solution is agitated with two successive quantities of distilled water, using 25 c.c. each time. The separation of the aqueous liquid from the chloroform occurs promptly and completely on warming the liquid slightly. The chloroform retains nearly the whole of the colouring-matter, while the alcohol and alkaloids (as salts) pass into the water.^ The aqueous layer is separated, and agitated once with chloroform to remove the last traces of colouring- matter; after which it is rendered alkaline with ammonia, and agitated twice with chloroform, using 25 c.c. each time, to extract the alkaloid. The separated chloroform is agitated once with water rendered faintly alkaline wnth ammonia, and then evaporated, the residue being dried at 100° till constant in weight. The alkaloid thus isolated is obtained as a perfectly transparent fused mass. It is soluble in water, and the aqueous solution gives pre- cipitates with Thresh's, Mayer's, and Sonnenschein's reagents (pages 136, 138). It gives a faint white precipitate with mercuric chloride, and a copious white precipitate with gallotannic acid cautiously added. This last precipitate is very readily soluble in a slight excess of the reagent, a distinct trace, however, invariably remaining undissolved (Farr and Wright).^ Instead of weighing the isolated alkaloid it may be titrated with standard acid and litmus (or methyl-orange) as recommended by Gerrard (Year-BooJc Pharm., 1884, page 447). D u n s t a n and Ransom ( Year-Book Pharm., 1 885, page 391) recommend continuous percolation with boiling absolute alcohol for the extraction of the alkaloids from belladonna leaves, and they proved that the leaves thus treated yielded no further ^ Cliloroform alone extracts the alkaloids very incompletely. Alcohol employed alone dissolves much extractive matter which impedes the subse- quent extraction and purification of the alkaloids. If rectified spirit instead of absolute alcoliol be employed in admixture with chloroform, the water pre- sent causes swelling of the material, and the progress of the extraction is seriously impeded. Dunstan and Ransom proved that the mixture of equal measures of chloroform and alcohol recommended by them completely extracted belladonna root, and that pure atropine was not appreciably aH'ected by pro- longed boiling with the solvent. 2 Although Dunstan and Ransom found the whole of the alkaloids to pass into the aqueous liquid, A. B. Lyons points out that it is desirable, as a precaution, to make a small addition of sulphuric acid to the water employed. ^ The alkaloids from stramonium behave similarly, probably owing to the presence of a small quantity of another (third ?) alkaloid. 266 BELLADONNA PREPARATIONS. quantity of alkaloid when boiled with dilute hydrochloric acid, or when mixed with lime and extracted with chloroform. From the extract obtained on evaporating the alcoholic liquid, they found it impossible to remove the whole of the alkaloid, even by many successive treatments with water or dilute hydrochloric acid. They therefore recommend that the alcoholic liquid should he diluted considerably with water acidulated with hydrochloric acid, and the liquid then shaken repeatedly with chloroform to remove the chlorophyll and fat.^ From the liquid thus purified the alkaloids can readily be obtained pure by adding excess of ammonia and extracting with chloroform. A modification of the foregoing process is recommended by D u n s t a n and Ransom for the assay of the solid extract of belladonna. Two grammes should be warmed with dilute hydro- chloric acid until as much as possible is dissolved, when the liquid is filtered through cotton or glass wool, and the residue well washed with hot dilute hydrochloric acid. The filtrate is repeatedly shaken with chloroform to remove chlorophyll, then ammonia added, and the liberated alkaloids extracted with chloroform. The tincture of belladonna can also be assayed by the foregoing process after evaporating off the greater part o"f the alcohol,^ and the same remark applies to the fluid extract. It is, however, in many cases preferable to treat the clear liquid at once with ammonia and chloroform. On subsequently treating the separated chloro- form with dilute sulphuric acid, the colouring-matters remain in ^ J. "Williams suggests that it would be better to employ ether at this stage of the process. ^ Farr and Wright have shown that the strength of alcohol used in ex- hausting the drug has little effect on the proportion of alkaloid in the tincture, though it very greatly affects the proportion of mucilaginous and colouring matters extracted, and the former of these impede the separation of the chloro- formic and aqueous layers. The difficulty may be overcome by evaporating the tincture to a syrup and treating it with strong alcohol, which precipitates the mucilage, and the filtrate gives on evaporation a liquid which can be readily dealt with. Farr and Wright find it impossible to remove the whole of the alkaloids of belladonna (and henbane) by repeated agitation with ether in presence of ammonia, at least 20 per cent, of the total remaining unextracted by ether, but recoverable by subsequent agitation with chloroform. Hence ether is an unsuitable solvent for extracting mydriatic alkaloids, and the results of Gerrard and others who have used it are probably below the truth. In fact, Gerrard himself states that several extractions with ether are neces- sary, and that, as a rule, he subsequently renders the ammoniacal solution neutral with citric or tartaric acid, evaporates it to a small volume, treats it again with ammonia, and again agitates with ether. ASSAY OF HENBANE. 267 the chloroform, while the alkaloids can be recovered in the pure state by rendering the acid liquid again alkaline, and agitating it with chloroform. A. W. G e r r a r d has employed substantially the same process as the above for the assay of the root and leaves of henbane {Pharm. Jour., [3], xxi. 212 ; xxii. 213). The substance is dried at 100°, powdered, and exhausted with proof-spirit. The spirit is distilled off, and the semi-fluid extract treated with water containing 1 per 1000 of hydrochloric acid, filtered, and the filtrate further diluted to 100 c.c. The alkaloids are extracted by ammonia and chloro- form in the usual way, purified by solution in ether, and agitated with hydrochloric acid ; again liberated by ammonia, extracted by ether, and determined in the alkaloidal residue by titration with deci- normal hydrochloric acid. The following results are recorded : — Variety of Henbane. Part Used. Where Grown. Yield of Alkaloids per 1000. Biennial, . Roots. Middlesex. 1-602 )» • " Sussex. 1-550 )i • • Lincolnshire. 1-729 First year's leaf. Lincolnshire. •690 >i " Sussex. •667 • Middlesex. •592 »i • • Second year's leaf, Middlesex. •672 Sussex. •680 . ,- Lincolnshire. •656 Annual, . Leaves and tops. Leicestershire. •641 >> 11 Surrey. •6S9 ,. Middlesex. •701 Annual. Entire herb. Germany. •295 Biennial, . First year's leaves. France. •398 ) (old). England. ■ •ago • • Second year's tops (old). England, •451 Gerrard's experiments appear to show that a considerable falling off in the alkaloidal value of the leaves occurs with age. He considers that bright-coloured, well-preserved henbane, whether annual or biennial, can be relied on to yield good preparations, while old and dark-coloured leaves, containing stalks and fruit, should be avoided. He regards the first year's root of biennial Hyoscyamus niger as much richer in alkaloids than the herbaceous portions of the plant, but both as much poorer than the respective parts of belladonna.^ Hyoscyamus alhus is much used in the south of Europe, but no greater strength is attributed to it. 1 These conclusions are entirely in opposition to the experience of E. Thorey (Dragendorft's Quelques Drogues Actives), who found henbane to contain alkaloid in greatest quantity in the leaves, next in the fruit, then in the roots, and lastly in the stalk. The substance was first exhausted with petroleum spirit to free it from fat, then dried, finely powdered, and extracted 268 STRAMONIUM. F. Eansom found 0'58 per 1000 of pure alkaloid in the seeds of biennial henbane grown at Hitchin. Henbane seed is used in Germany for the preparation of the alkaloid. F a r r and Wright {Pharm. Jour., [3], xxii. 255) have proved that practically the whole of the alkaloid of henbane is contained in the tincture. From 100 c.c. of tincture (corresponding to 12 '5 grammes of the substance), prepared from different parts of the plant, they obtained the following weights of alkaloid : — From 100 c.c. of Tincture. From 100 parts of Substance, Dried leaves, average, 0-0103 grammes. 0-0824 per cent. Recently dried fresh leaves. 0-013 0104 „ Seeds, .... 0-015 0-120 „ Root-bark, , 0-020 0-160 „ From stramonium seeds, J. D. A. Hartz {Pharm. Jour., [3], XV. 203) obtained 0*167 per cent, of alkaloid, by extracting the fat from the dried substance by petroleum spirit, then removing the alkaloid with proof-spirit, and proceeding in the usual way. F a r r and Wright found from 0*1 6 to 0*24 per cent, of alkaloid in stramonium seeds. E. Schmidt found, in four samples of stramonium seed from different sources, 0*25, 0*37, 0-05, and 0*20 per cent, of total alkaloids. From 50 to 70 per cent, of these con- sisted of pure atropine melting at 115° C. The remainder, which was much more difficult to crystallise, consisted of hyoscyamine, and probably other bases and their decomposition-products. But the relative proportions of the alkaloids are probably very variable, as with faintly acidified rectified spirit at a temperature of 80°-40° C. The alcohol was distilled off, and the residual liquid filtered. The filtrate was purified by agitation with chloroform or petroleum spirit, then rendered alkaline with potash or ammonia, and the alkaloid extracted by agitation with chloroform. The following figures, by Thorey, represent the percentage pro- portions of alkaloids obtained from the dried materials : — Part of Plant. Plant destitute of Flowers. Plant in Flower. Plant in Fruit. Hyosc. albus. Hyosc. niger. Hyosc. albus. Hyosc. niger. ! Hyosc. albus. 1 Hj^osc. niger. 1868 1869. 1868. 1869. 1868. 1869. 1868. 1869. ' 1868. 1869. 1868. 1869 Seeds, . ... ... ... ... 1 ... ... 0-162 0-172 0-075 0-118 Leaves, . 0-588 0-469 0-154 0-192 0-359 0-329 0-147 0-206 0-211 153 0-065 0-110 Stalk, . 012 ... 070 0-017 ; 036 0-048 0-032 030 027 0-029 0-009 010 Root, . 128 0176 0-027 0-080 0-146 0-262 0-127 0-138 0-106 0-086 0-028 [ 056 EXTRACT OF BELLADONNA. 269 Ladenburg found hyoscyamine to prejDonderate, and Schiitte found that both fresh and old stramonium seeds yielded chiefly hyoscyamine, with small quantities of ready-formed atropine and scopolamine. A. B. Lyons {Manual of Pharmaceutical Assay- ing) found in five specimens of stramonium seed proportions of alkaloid (titrated by Mayer's solution) ranging from 0*45 to 0"55 per cent., the extractive matter yielded to strong alcohol by the same samples varying from 3 '3 to 7 '5 per cent. In eight samples of stramonium leaves, Lyons found from 0'40 to 0*52 per cent, of alkaloid (titrated), and from 19*5 to 25*3 per cent, of extractive matter yielded to spirit of 66 per cent. Fair and Wright ex- tracted from 0*12 to 0*22 per cent, of alkaloid from stramonium leaves. R. K r d e s (" Inaugural Dissertation," Dorpat, 1888) found the following percentages of alkaloid in the sources stated : — Leaves. Roots. Belladonna, .... 0'61 per cent. 0'74 per cent Hyoscyanius, . . . . 015 ,, 0"13 „ Stramonium, .... 0*20 ,, 0*15 ,, R. Kordes has also published the results of analyses of a large number of tetrads of belladonna, henbane and stramonium.-^ His figures show the yield of ^extract, the percentage of water and alkaloid in the preparation, and the proportion of total alkaloid obtained in the extract. Dun Stan and Ransom (Pharm. Jowr., [3], xvi. 777) found the alkaloids in nine commercial specimens of solid extract of bella- donna root to vary from 1"65 to 4'45 per cent., the water ranging from 16'0 to 21 '6 per cent. They state that the extract contains, besides atropine and hyoscyamine (and possible traces of another alkaloid), the fluorescent substance called chrysatropic acid (page 262) and " much dextrose." This observation is of interest in rela- tion to the assumption of Schweissinger (Pharm. Zeit, 1886, page 101), that a genuine extract of belladonna leaves contains no substance capable of reducing Fehling's solution at a temperature of 60°-70° C, any reddish turbidity or precipitate being probably due to sojDhistication with dextrin or the extract of dulcamara or taraxacum. Analyses of various extracts of belladonna have been published by J. C. Umney {Pharm. Jour., [3], xxii. 364). L. van Itallie recommends that the extracts of belladonna and henbane should be assayed by treating 5 grammes of the sample with 10 drops of dilute sulphuric acid (1 :20), diluting with water to 50 c.c, and macerating for some hours. Twenty-five c.c. of a 10 per ^ Also analyses of extracts of conium, cheledonium, aconite, nux vomica and physostigma. 270 ECGONiNE DERIVATIVES. cent, solution of lead acetate is then added, and after allowing the precipitate to settle the liquid is passed through a dry filter. From 50 c.c. of the filtrate the excess of lead is precipitated by 10 c.c. of dilute sulphuric acid (1:10), and the liquid again filtered. From 50 CO. of this second filtrate the alkaloids are then liberated by ammonia, extracted by three agitations with chloroform, the solvent evaporated, and the residual alkaloids dissolved in spirit and titrated with centinormal acid. COCA ALKALOIDS.^ The leaves of Erythroxylon coca and allied species ^ contain a number of closely-allied alkaloids, all of which appear to be derivatives of e c g o n i n e, CgH^gNOg, a base which E i n h o r n and Hesse regard as a derivative of tetrahydropyridine (pages 106, 164), and to which they assign a constitution expressed by the following formula : — ^„ j CH2.CH[CH(OH)CH2.CO.OH] \^ r.^ ^^2|cH:CH |iN.v.±i3 According to this formula, ecgonine is methyltetrahydro- pyridyl-/3-hydroxy propionic acid. When heated with baryta, it splits into carbon dioxide and isotropine, and hence may be regarded as isotropyl-carboxylic acid. Me. CgHyN.CHlOH). CHa- COOH = COg + Me.05H7N.CH(OH). CHa- H Ecgonine. Isotropine. The relation between ecgonine and isotropine (and therefore between cocaine and atropine) is equally evident from a comparison of the formula of their respective anhydrides : — Anhydro-ecgonine. Tropidine. The hydrogen of the hydroxyl-group of ecgonine can be substi- tuted by acetyl, benzoyl, cinnamyl, and other acid-radicals. Thus : — Benzoyl-ecgonine, Me.C5H7KCH(O.C7H50).CH2.COOH Cinnamyl-ecgonine, Me.C5H7N.CH(O.C9H70).CH2.COOH ^ The author is indebted to Dr B. H. Paul and Mr A. J. Cownley for perusal and correction of this section. 2 Upwards of eighty species of the genus Erythroxylon are found in Brazil [Pharm. Jour., [3], xvii. 507); but most of these species, other than E. coca, yield very little cocaine {Pharm. Jour., [3], xix. 70). BASES OF COCA. 271 By heating those compounds with alkyl iodides, the correspond- ing esters may be obtained : — Methyl beuzoyl-ecgonine (cocaine), MeC5H7N.CH(O.C7H50).CH2.CO.OCH3 Ethyl beiizoyl-ecgonme(homococaine), MeC5H7N.CH(O.CVHgO).CHo.CO.OC2H5 Methyl cinuarayl-ecgouiiie, . . MeU5H7KCH(O.C9H70).CH,.CO.OCH8 Methyl benzoyl-ecgonine or cocaine is the most important and characteristic of the bases of coca. Methyl cinnamyl-ecgonine occurs occasionally, in small quantity, in the broad-leaved South American coca, and regularly, and sometimes in considerable quantity, in Truxillo coca. When dibasic acids react on ecgonine, bodies of more complex constitution result. One of these (the methyl-ester of a substance polymeric with cinnamic acid, called by Hesse cocaic acid, CigHigO^, and by Liebermann y-isatropic or truxillic acid), is the c o c a m i n e, CggH^^NoOg, of Hesse, and the isatropy 1-cocaine or a-truxilline of Liebermann. The next higher homologue of cocayl-ecgonine methyl-ester also appears to exist in coca, as also the corresponding derivatives of iso-cocaic (^-truxillic) andh om o-isoco cai c acids. The following is a list of the bases hitherto detected in coca leaves. The amorphous base to which Hesse gave the name of cocaidine has been proved to be a mixture ; and the volatile base called h y g r i n e by Lessen has not since been obtained. CjHiyNOa, Anhydro-ecgonine, CgHigN j cQ } ; or MeCjHyN.CHiCH.COOH \ OH C9H15NO3, Ecgonine, . . CgHjaN j qq.OH CigHiyN04, Betizoyl-ecgonine, CgHjgNj C17H21NO4, Benzoyl-ecgonine methyl-ester (cocainej, O.C^HjO CO. OH r, XT AT f O.C9H7O Ginnamyl-ecgonine, CgMiaiN -! ^^ ^^ C19H23NO4, Cinnamyl-ecgonine I fO-CgH^O methyl-ester, \ ^sHis^ j CO.OCH3 C3sH4eN,Os,Cocayl - ecgonine >. o.OCH3)0 ) ^ „ ^ methyl-ester U H 3N(C0.0CH )0 i ^^«^^*^^ (cocamme), j a -w \ ^' C40H60NA, Homococamine, IC8H,3N'(C0.0CH3)0 ) CicHio(CHo)«0. J C8Hi3N(CO.OCH3)0 i '' '-^ ^^' " C17H19NO2, Benzoyl-pseudo- I CH^^NOCCVH^O) tropine, j o 14 Isomerides of cocamine and homococamine probably exist in coca, as Hesse has isolated from the products of hydrolysis i s 0- 272 HYDROLYSIS OF COCA BASES. c c a i c and homo-isococaic acids. Similarly, Lieber- mann has isolated two isomers of cinnamic acid, i s o c i n ii a m i c and allocijinamic acids, from the products of the decom- position of coca bases. With the exception of ecgonine and anhydro-ecgonine, all the bodies in the foregoing list are saponifiable, splitting up when heated to 80°— 100° with hydrochloric acid, or when boiled with alcoholic potash, according to the following equations : — 2. 3. 4. a. C17H21 NO4 Cocaine. H20 = Ci6Hi9N04+CH,0 '16' Benzoyl-ecgonine. Methyl alcohoL Benzoyl-ecgonine. H,0 = C,H,,N03 +C,H,0, Ecgoiiine. Benzoic acid. a. H,0 C,8H2,NO, + CH,0 Cinnamyl-ecgonine metliyl-ester. 6. C,,ll,,'SO, a. + H20 = Cinnamyl-ecgonine. NjOg-l-SHaO C3SH, Cocamiue (truxilline). h. C2,H2<,NO, 4- Ecgonyl-cocaic acid. H2O Cinnamyl- ecgonine. C,H,,N03 Ecgonine. = C,Hi,N03 Ecgonine. C,H„NO, Ecgonine. Methyl alcohol. + C8HA Cinnamic acid. + C27H29NOe + 2CH40 Ecgonyl-cocaic Methyl acid. alcohol. + ^18^1604 Cocaic acid (a-truxillic acid). CiyH^gOg + H2O Benzoyl-pseudotropine. Pseudotropiue. Benzoic acid. From these equations it is evident that the simpler bases of coca are decomposition-products of the natural alkaloids cocaine, cocamine, homococaniine, and cinnamyl-ecgonine methyl- ester (cinnamyl-cocaine), all of which readily undergo hydrolysis with for- mation of ecgonine, methyl alcohol, and an aromatic acid. Benzoyl-pseudotropine differs from the other bases of coca by yielding no methyl alcohol on hydrolysis. It is evident that the mixed alkaloids of coca will consist of the various natural bases in indefinite proportion, contaminated by the products of their decomposition. Hence the separation of pure cocaine from the co-existing bases is very troublesome. The difficulty has been overcome by Liebermann and G i e s e 1 {Ber., xxi. 3196) in an interesting and ingenious manner, which allows of the utilisation of the valueless and troublesome amorphous bye-products, which are to be had in considerable quantity. The process consists in boiling the mixed bases with hydrochloric acid, whereby they all suffer hydrolysis, with formation of ecgonine; and this base forms the starting-point for the subsequent synthesis SYNTHESIS OF COCAINE. 273 of cocaine by Ein horn's method (5er., xxi. 3335). Thus by- passing dry hydrochloric acid gas into a solution of ecgonine hydro- chloride in methyl alcohol until the solution has become cold, and then boiling the liquid for an hour under an inverted condenser, the hydrochloride of ecgonine methyl-ester is formed, which on concentrating the alcoholic solution crystallises in prisms, melting with decomposition at 212°. Cocaine is formed when this com- pound is heated on the water-bath with an equal weight of benzoyl chloride until the mixture becomes homogeneous and the evolution of hydrochloric acid ceases. The hot melted mass is poured into water, separated from the precipitated benzoic acid, and the cocaine precipitated by ammonia or an alkaline carbonate, and recrystal- lised from alcohol. An alternative method is to convert the ecgonine into the benzoyl-derivative, and treat a solution of the latter body in methyl alcohol with hydrochloric acid gas. The artificial cocaine prepared by either of these methods possesses all the characters of the natural alkaloid. Cocaine. Benzoyl methyl-ecgonine. Methyl benzoyl-ecgonine. C^H^iNO,; or CsHtCCH,)^^ | ^jg^^^^J^jj^ Cocaine is the characteristic alkaloid of coca leaves, and has recently acquired a place in the first rank of alkaloids of medicinal value. It may be extracted from the plant by the usual processes, avoiding as much as possible treatment with acids and alkalies, as it undergoes hydrolysis with great facility with formation of objec- tionable decomposition-products. The synthesis of cocaine was efi'ected by Merck by treating together ecgonine, benzoic anhydride and methyl iodide to 100° for ten hours in a sealed tube. The industrial reproduction of cocaine from ecgonine has been efi'ected and patented by Liebermann (page 272). Cocaine crystallises from a strong alcoholic solution in colourless monoclinic prisms, melting at 97°-98° C, and subliming with partial decomposition at a higher temperature. Cocaine is very slightly soluble in water,^ but dissolves readily in alcohol, ether, chloroform,^ benzene, petroleum spirit, carbon ^ The solubility of cocaine in cold water is probably near to 1 in 1300 (B. H. Paul), but is commonly greatly over-estimated, owing to the ease with which cocaine is decomposed by hot water with formation of soluble products, ^ The solubility of cocaine in chloroform enabled B. H. P a u 1 to separate it from morphine, and prove a product introduced under the name of h o p e i n e, and said to be a natural narcotic alkaloid from American hops, to be, in fact, an artificial mixture of cocaine and morphine {Pharm. Jour. , [3], xvi. 877). VOL. III. PART II. S 274 CHARACTERS OF COCAINE. disulpliide and volatile and fixed oils. Jt is readily removed trora its solutions by adding ammonia and agitating with ether or other immiscible solvent. An aqueous solution of cocaine has a strong alkaline reaction to litmus and methyl-orange, but does not affect phenolphthalein. The free base may be titrated with the aid of either of the former indicators. An aqueous solution of cocaine, if not very carefully prepared and secluded from air, or preserved by an antiseptic, mpidly decomposes with formation of vegetable growths. Cocaine produces on the tongue a sudden and characteristic cessation of feeling, which lasts only a few minutes. One drop of a 4 per cent, solution (of the hydrochloride), if placed on the tongue, soon produces a decided numbness, the effect being evanescent unless the application be repeated. Cocaine also pro- duces an intense local anaesthetic and blanching effect on the raucous membrane. A single drop of a 4 per cent, solution suffices to blanch the conjunctiva of the eye. Anaesthesia of the eye, of much value in ophthalmic operations, can be produced by a some- what larger dose. Dilation of the pupil is generally produced by cocaine, whether applied locally to the eye or otherwise introduced into the system ; but the mydriasis produced by cocaine is not so invariable and is far less intense than that characteristic of atrojDine and its isomers. In large doses, cocaine has marked poisonous properties. The fatal dose for dogs is from 2 to 5 grains. The hypodermic injec- tion of -^Q grain has caused dangerous symptoms in a girl twelve years of age (see Pharm. Jour., [3], xvi. 721)/^ Cocaine is Isevo-rotatory, the specific rotation in chloroform solu- tion being about — 15°*8 for the sodium ray; while the rotation of the hydrochloride in dilute alcohol is — 52°'2. Eeactions of Cocaine. Cocaine is precipitated from its solutions by caustic alkalies, alkaline carbonates and ammonia. It is almost insoluble in excess of ammonia, which is to be preferred as a precipitant.^ Precipitated cocaine is amorphous when thrown down from strong solutions, but rapidly becomes crystalline. ^ For various alarming symptoms produced by cocaine in dental practice, see remarks by Stockman {Pharm. Jour., [3], xviii. 791). A resume of the pharmacology of cocaine and its allies appeared in the Pharmaceutical Journal, [3 J, xxi. 161. 2 If a solution of cocaine salt be precipitated with caustic soda or sodium carbonate, the filtrate will be found to contain a distinct trace of benzoic acid resulting from decomposition of the alkaloid ; but this is not the case if ammonia be substituted (B. H. Paul). REACTIONS OF COCAINE. 275 Mayer's solution precipitates cocaine from extremely dilute solu- tions, and A. B. Lyons has attempted to employ the reaction for the determination of cocaine, but with results which are wanting in exactness. Iodised iodide of potassium gives a rose-coloured precipitate with a solution of 1 part of cocaine hydrochloride in 7,500 of water; in stronger solutions the precipitate appears hrown, and under the microscope assumes the form of black globules. Tannin produces a distinct cloud in neutral solutions of cocaine containing 1 : 25,000, and a distinct precipitate wdth twice that proportion. Picric acid produces in strong solutions a yellow precipitate, rapidly becoming crystalline, and appearing under the microscope in sheaf-like forms. Phosphomolybdic acid produces a faint turbidity in solutions of 1 : 50,000, and a distinct pre- cipitate with 1 : 12,500. Phosphotungstic acid gives a gelatinous white precipitate, soluble in ammonia. Platinic chloride produces at once, in solutions of cocaine hydro- chloride containing 1 : 400, a yellow precipitate consisting of plumose needles, mostly of stellate pattern. In solutions of 1 : 600 most of the crystals resemble carpet-tacks, consisting of short, well-formed prisms, with a single branch from the centre, joined at an oblique angle and tapering to a point. The characters of the chloroplatinate distinguish cocaine from the amorphous base associated with it in coca-leaves, the platinum salt of which is far less soluble in water, and crystallises in rosette-like forms, contrasting strongly with the feathery appearance of the cocaine salt. Cocaine aurochloride is precipitated on adding auric chloride to a solution of cocaine hydrochloride. In solutions containing 1 : 3000 an immediate precipitate is produced, which appears under the microscope in forms resembling fern-fronds, generally with a stellate arrangement. In solutions of 1 : 12,000 similar crystals form after a short time. " Cocaidine " aurochloride forms minute prismatic crystals, having a microscopic appearance quite different from that of the cocaine salt (A. B. Lyons, Amer. Jour. Pharm., Ivii. No. 10). According to Lerch and Scharges, if a drop of ferric chloride be added to a solution of cocaine and the liquid boiled, an intense red colour will be developed " owing- to the formation of benzoic acid." Benzoyl-ecgonine also gives the reaction. Potassium bichromate does not precipitate cocaine except from neutral solutions, unless they are very concentrated (1:25); but M e t z e r states that from a solution containing hydrochloric acid, chromic acid precipitates the chromate, CiyHgiNO^jH^CrO^, in 276 COCAINE PERMANGANATE silky, lustrous plates (compare page 287). If 0*05 gramme of cocaine hydrochloride be dissolved in 5 c.c. of water, and five drops of a 5 per cent, aqueous solution of chromic acid added, each drop produces a distinct precipitate, which immediately redissolves ; but if 1 c.c. of strong hydrochloric acid be now added, a heavy yellow precipitate of cocaine chromate is produced. If cocamine be present, reduc- tion of the chromic acid will ensue. Ecgonine, sparteine, atropine, caffeine, pilocarpine, codeine and morphine do not form yellow precipitates with chromic acid or potassium chromate. Quinine, quinidine, cinchonine, cinchonidine, hydroquinine, apomorphine, brucine, strychnine and veratrine form precipitates with 5 per cent, chromic acid if the solutions are neutral ; but, according to K. Metzer (Pliarm. Zeit., xxxiv. 697), cocaine is singular in being precipitated only after addition of hydrochloric acid. F. Giesel (Pharm. Zeit, 1886, page 132) has observed that cocaine permanganate is very stable compared with the corre- sponding salts of the majority of alkaloids. Hence, if 1 centi- gramme of cocaine hydrochloride be dissolved in one or two drops of water, and about 1 c.c. of a 3 per cent, solution of potassium permanganate be added, a purple-violet crystalline precipitate of cocaine permanganate is produced, the supernatant liquid acquiring a purple-violet tint. A. B. Lyons recommends that a strong solution of the cocaine salt should be used, and the per- manganate employed in decinormal solution (3'162 grammes per litre). The precipitate is unstable, and decomposes in a few hours even at the ordinary temperature, leaving a brown hydrated man- ganese dioxide. If the liquid containing the precipitate be heated to boiling decomposition occurs at once, but without the production of any peculiar odour. But if examined under the microscope when first thrown down, the precipitate is found to consist, wholly or in part, according to the strength of the cocaine solution, of translucent, violet-red, rhombic (nearly rectangular) plates of great beauty, often grouped together to form rosettes. A 5 per cent, solution of cocaine gives a copious precipitate at once, and a 2 per cent, solution after a short time ; but with a 1 per cent, solution the crystals only form as evaporation takes place. The behaviour with potassium permanganate serves to detect an admixture of methyl cinnamyl-ecgonine and certain other im- purities in cocaine hydrochloride. The presence of these causes an immediate reduction of the permanganate in the cold. The first drop or two of the reagent produces a brown discoloration, while the precipitate thrown down by a further addition is more or less brown, instead of a distinct violet-purple or red. If a limited qiiantity of the reagent be employed, and the liquid heated to SALTS OF COCAINE. 277 boiling, in presence of impurities a distinct odour will be developed in some cases resembling that of bitter-almond oil, and in others like that of crude cocaine (A. B. Lyons, Amer. Journ. Pharm., 1886, page 240). The behaviour of other alkaloids with potassium permanganate is described on page 144. According to F. da Silva (Compt. Bend., cxi. 348; Pharm. Jour., [3], xxi. 162), when treated by Vitali's test for atropine (page 257), even a minute quantity of cocaine (0'0005 gramme) developes a distinct and peculiar odour, recalling that of pepper- mint or citronella. No other alkaloid extracted by benzene from an amnion iacal solution behaves at all similarly, though atropine, hyoscyamine, strychnine, codeine and eserine give colour-reactions, and the last-named alkaloid developes a disagreeable smell resem- bling phenyl-carbamine (page 46). Delphinine, brucine, and vera- tiine develop slight odours which cannot be mistaken for that produced by cocaine. A. C. Stark (Pharm. Jour., [3], xxi. 848) has confirmed Da Silva's statements, but considers the odour scarcely distinctive enough to render the test completely reliable. Salts of Cocaine. Cocaine Hydrochloride. Hydrochlorate of Cocaine. C^yHg^N O^jHCl. This salt, wdiich is readily prepared by neutralising cocaine by hydrochloric acid, crystallises from alcohol in short prisms melting at 181°'5. The crystals from the aqueous solution contain, according to A. B. Lyons, 9 '6 per cent, of water, while those from the alcoholic solution are anhydrous. The salt is not hygroscopic, but is soluble in less than its own weight of water, forming a thick syrupy liquid. It is readily soluble in spirit, but with less facility in absolute alcohol, chloroform, and amylic alcohol ; and is prac- tically insoluble in ether, petroleum spirit, and fixed and volatile oils. Ether precipitates cocaine hydrochloride from its solutions in absolute alcohoP and chloroform. Cocaine Hydrohromide, BHBr,2H20, crystallises readily from its aqueous solution in transparent prisms, stable in the air. Cocaine Acetate is readily soluble in water. It is difficult to obtain it in a crystalline condition, as acetic acid is given olf during the evaporation of its solution. Cocaine Oleate readily crystallises, and is soluble in oleic acid and fixed oils. Cocaine gives crystalline salts with sulphuric, boric and oxalic acids. The citrate is hygroscopic, and crystallises with difficulty. ^ Stockman {Pharm. Jour., [3], xvii. 862) gives the sohibiKty of pure cocaine hydrochloride in chloroform, absolute alcohol, and amylic alcohol ab 1 in 48, 1 iu 34, and 1 in 70 respectively ; but B. H. Paul does not tind such large proportions of solvent necessary. 278 COMMERCIAL COCAINE. Cocaine Benzoate, Ci^Hg^NO^jC^HgOg' ™'^y be prepared by mixing molecular proportions of cocaine and benzoic acid. It is a very soluble salt, obtainable with difficulty in acicular crystals, the solution usually drying up to a gummy mass, which gradually acquires a crystalline structure. A sample of commercial cocaine benzoate of French origin was found by B. H. Paul to give no precipitate of cocaine with ammonia, and no benzoic acid with hydrochloric acid. It consisted ofbenzoyl-ecgonine (Pharm. Jour., [3], xvi. 817). According to A. Bignon (Pharm. Jour.^ [3], xvi. 721), the anaesthesia produced by a 5 per cent, solution of cocaine benzoate lasts during four consecutive hours, and is not preceded by the sensation of pain produced by the hydrochloride. Examination of Commercial Cocaine and its Salts. The absolute purity of cocaine and cocaine salts intended for medicinal use is essential, as various undesirable and even dangerous symptoms are produced by certain impurities liable to be present.^ Orude Cocaine has for some time been manufactured in South America for export to European markets in place of coca leaves, which have been found liable to deterioration in transit. B. H. Paul {Pharm. Jour., [3], xviii. 782) describes it as a white or yellowish pulverulent substance compressed into thin cakes. It contains not only earthy substances, sodium carbonate and lime salts, but also a waxy substance and traces of petroleum. Its manufacture has probably been effected by extracting the coca leaves with petroleum spirit, washing out the alkaloid with an acid, and then precipitating it with lime or sodium carbonate. It is represented as containing from 80 to upwards of 90 per cent, of alkaloid, but the proportion of crystallisable cocaine present varies considerably, in one instance not exceeding one-half of the total alkaloid present (85 per cent.). The remaining portion was pre- cipitated on adding ammonia to its solution in hydrochloric acid in oily globules, which after a time collected at the bottom of the liquid as a viscid semi-transparent layer, which ultimately became more or less crystalline. In all cases the liquid remained quite 1 The characters and tests for cocaine hydrochloride given in the British Pharmacopeia of 1885 are inadequate, and in several respects grossly in- accurate. In the first issue, it was incorrectly described as readily soluble in ether, whereas in fact it is practically, if not absolutely, msoluble. This mistake is corrected in the reprint, but the aqueous solution is still described as having a bitter taste, which is not a characteristic of the pure salt, and is said to yield a white precipitate with carbonate of ammonium, soluble in excess of the reagent, which is not the fact. "The aqueous solution dilates the pupil of the eye. It (? the aqueous solution) dissolves without colour in cold concentrated acids, but chars with hot sulphuric acid. " CHARACTERS OF COCAINE. 279 milky for a considerable time, in this respect presenting a marked contrast to the rapid clearing of the liquid, which takes place when pure cocaine is precipitated from the solution of its hydrochloride. The analysis of a sample of crude cocaine by E. R. Squibb showed: — Moisture, 3'25 per cent.; residue insoluble in ether, 5*25; impurity soluble in ether, 050; pure alkaloid, 89'94 ; and loss, r06 per cent. {Jour. Soc. Cliem. Ind., viii. 724, 1013). A convenient method of purifying cocaine is to recrystallise it several times from strong alcohol, and, when a certain degree of purity has been attained, precipitate the base from its solution in 10 parts of strong alcohol by addition of 5 measures of water. Paul and C o w n 1 e y have pointed out that the solubility of a sample of cocaine in petroleum spirit cannot be relied on as a proof of its purity, since cinnamyl-cocaine behaves similarly. John Williams {Year-Book Pharm., 1887, page 502) pro- posed to purify and assay commercial cocaine hydrochloride by dissolving it in the smallest possible quantity of absolute alcohol (sp. gr. 0'795), and adding to this solution six times its measure of dry ether, when the cocaine hydrochloride is precipitated in a finely-divided but perfectly crystalline condition. Unfortunately, as pointed out by B. H. Paul, the hydrochlorides of the amorphous bases and of benzoyl-ecgonine are precipitated under the same con- ditions ; and hence the method is useless for the assay of crude cocaine hydrochloride or for the elimination of impurities, though serviceable for improving the appearance of a pure salt and con- verting it into a convenient form for use.^ Cocaine hydrochloride should be perfectly colourless, and soluble in water to a perfectly colourless solution, which ought to be absolutely neutral to litmus-paper. The solution of the pure salt keeps fairly well, but in presence of common impurities is decomposed with great facility. In the dry solid state, cocaine hydrochloride under- goes no change by keeping. It ought to be perfectly free from odour; but as sold it not unfrequently retains the odour of a solvent used in its preparation, or has a peculiar butyric or mousy smell, or even a distinct benzoic odour. In any case, a sample having a distinct odour must be regarded with suspicion. Pure cocaine hydrochloride is always distinctly crystalline, though much of the commercial article presents an amorphous or granular ^ Paul adds that it is a mistake to attempt the purification of cocaine hydro- chloride at all. The free alkaloid is much more susceptible of purification, and may be obtained in very fine crystals either from ether or alcohol. From pure cocaine the hydrochloride can be readily prepared, as the neutral solution maybe evaporated to dryness without decomposition, and the resultant dry salt can be readily converted into a good-looking crystalline condition 'by* Williams' method. 280 COCAINE HYDKOCHLORIDE. appearance. The tendency to crystallise is so marked that B. H. Paul {Pharm. Jour., [3], xviii. 781) regards an amorphous condi- tion, or even difficult crystallisability,as an indication of the presence of impurity. Paul states that on dissolving 5 to 10 grains of a pure sample in 1 drachm of water and rapidly evaporating the solution (in a glass basin) on a water-bath, the dry residue obtained will be white and opaque, presenting a radiating crystalline structure, while in the case of an impure mixed salt the residue will be more or less yellow, translucent, and of a gummy or resin oid character. The most definite test for the purity of cocaine hydrochloride is said by Antrich (^Ber., xx. 310) to be the optical activity. In dilute alcoholic solution, at 20° C, the specific rotatory power is S„= -(52°-18 + 0-1588g),andS„= - (67-982 -0-15827c); where q is the weight of dilute alcohol of "9353 specific gravity at ^ (which corresponds to a mixture of 6 parts by weight of absolute alcohol with 9 parts of water) in 100 parts by weight of the solution, and c is the weight of hydrochloride in 100 volumes of the solu- tion. When g = 0, or, in other words, the solution is aqueous, S„= - 52°-2 ; when q is 100, S„= - 68°-06. The characteristics of cocaine hydrochloride should be, according to Beckurts, that it should give a clear and colourless solution in water ; leave no residue on ignition ; give a colourless solution in concentrated sulphuric acid, when dissolved in the proportion of 0'020 gramme to 1 c.c. ; that a concentrated aqueous solution should be absolutely neutral (to litmus) ; not immediately reduce potassium permanganate ; and when heated with the latter reagent give off no odour of bitter-almond oil. The German Pharmacopoeia (1890) prescribes the following tests for cocaine hydrochloride : — 0*1 gramme is dissolved in 5 c.c. of water, and 3 drops of diluted sulphuric acid added. This solution should be coloured violet by 1 drop of a 1 per cent, solution of potassium permanganate, and if kept in a closed vessel the colora- tion should but slightly decrease in half an hour. One c.c. of sulphuric or nitric acid should dissolve O'l gramme of a cocaine salt without coloration. The following test is due toH. Maclagan {Amer. Drug., 1 887, page 22 ; Pharm. Jour., [3], xvii. 686) : — One grain of cocaine hydrochloride is dissolved in 2 ounces of water, 2 drops of strong ammonia are added, and the walls of the containing vessel rubbed from time to time with a glass rod ; in a quarter of an hour a good crop of glistening crystals separate. When the cocaine is not very pure the solution remains clear, or else deposits only a small crop. With a good sample a dense precipitate is produced either at once or on stirring, and soon acquires a crystalline condition, COMMERCIAL COCAINE. 281 the liquid rapidly clearing. When the cocaine contains more than 4 per cent, of amorphous alkaloid the solution becomes milky. B. H. Paul (Pharm. Jour., [3], xviii. 783) has pointed out that the precipitate of cocaine produced in Maclagan's test redis- solves if left for a long time in the ammoniacal solution, owing to its conversion into the soluble base benzoyl-ecgonine. He describes a quantitative application of the ammonia test (using a 2 per cent. solution of the salt) which, in the case of good samples free from odour and colour, will fairly indicate the purity and value ; but, in the case of bad samples, regard must also be paid to the character of the precipitated alkaloid. This is done by adding the ammonia gradually, with constant stirring, as long as a crystalline precipitate forms and the liquid clears promptly. When the precipitate begins to form clots which adhere to the sides of the beaker, and the liquid remains milky, the precijDitate already formed is separated, and the amorphous precipitate produced on further addition of ammonia collected separately.^ The following results were obtained by B. H. Paul by the examination of commercial cocaine hydro- chloride by the above process ; — Ammonia Precipitate, per cent. Sample Number. Water, per cent. 1 On Sample. i = 0n Dry Salt. 1 •90 85-6 86-3 2 ■50 84-3 84-7 3 84-0 84 4 I'oo 83-6 84-00 6 •43 82-6 82^95 6 1-19 81 •SS 82^33 7 •43 81-04 81-40 8 9^47 74-9 8-2-75 9 2 00 /Cryst. 66-4 > iAmorph. 12-2 f 80-2 10 0-57 / Cryst. 43 -28). \Amorph. 31-93) 78-66 11 2^93 y Cryst. 41-7 > \Amorph. 31-7 f 75-5 12 ... 65-3 ... The ammonia precipitates from the first eight of these samples were perfectly crystalline, without any trace of stickiness ; they deposited rapidly, and left the supernatant liquid quite clear and bright. In the case of samples 9, 10 and 11, a considerable proportion of the alkaloid was of an amorphous sticky nature, quite different from that obtained from a pure salt. No. 12 was so impure that it was impossible to effect a fractional precipitation quantitatively. ^The amorphous alkaloid when freed from colouring matter is a clear yellowish transparent substance, resembling thick Canada- balsam, and the hydrochloride forms a varnish-liku mass that cannot be reduced to powder. BENZOYL-ECGONINE. Paul states that the principal impurity iu the last four samples was undoubtedly the hydrochloride of the amorphous alkaloid associated with cocaine in coca leaves (see page 287), the salts having been probably produced by evaporating the solution of the mixed bases in hydrochloric acid ; and it is questionable whether the presence of this amorphous base should be tolerated in a pro- duct which purports to be " cocaine hydrochloride." Decomposition-Products of Cocaine. Benzoyl-ecgonine. CieHjgNO^; or C8Hi3N(O.CyH50).CO.Oa This base may be prepared by the action of benzoic anhydride or benzoic chloride on ecgonine, and is also a product of the action of acids or water on cocaine. Hence it occurs as a bye-product of the manufacture of cocaine.^ On a large scale, benzoyl-ecgonine is prepared by gradually adding a little more than one molecule of benzoic anhydride to a hot saturated aqueous solution of one molecule of ecgonine, and heating the mixture on the water-bath for about an hour. After cooling, the product is shaken with ether to remove unchanged benzoic anhydride and acid, and the residual benzoyl-ecgonine washed with a little water to dissolve unaltered ecgonine. The yield is about 80 per cent, of the ecgonine employed, and an additional quantity can be obtained by concen- trating the mother-liquor and again treating it witli benzoic anhydride. Benzoyl-ecgonine crystallises with 4H2O in transparent, flat, trimetric prisms, resembling ammonium oxalate, which melt at a variable temperature ranging from 87°-140°. When fusion occurs at the lower temperature (as happens when the heat is rapidly applied), the substance resolidifies on further heating, and melts again at 195°, turning brown at the same time. Benzoyl-ecgonine is sparingly soluble in cold water, but readily in hot water, alcohol, and dilute alkalies and acids. It is almost insoluble in ether. The acetate and sulphate of benzoyl-ecgonine crystallise in prisms. BHAuCl^ forms small, yellow, anhydrous scales, soluble in alcohol but only sparingly so in water. When heated with alkalies or with hydrochloric acid to 100° in sealed tubes, the base is decomposed into benzoic acid and ecgonine. By treatment with methyl iodide it yields cocaine. 1 Benzoyl-ecgonine is easily produced by heating cocaine with about 20 parts of water in a closed tube. The cocaine melts at about 90°, but gradually dissolves on maintaining the temperature at 100°. The change is facilitated by agitation, and in about twelve hours a clear solution is obtained, which is only faintly acid if pure cocaine was employed. ECGONINE. 283 Benzoyl-ecgonine does not appear to have much, if any, anaes- thetic effect when applied to the eye, and exerts only a moderate dilating action on the pupil. R. Stockman states that it is very irritating to the mucous membranes, and vrhen injected sub- cutaneously produces tetanic spasms. In many respects its action resembles that of caffeine, but paralysis of the sensory nerves is quite absent (Pharm. Jour., [3], xvi. 898). EcGONixXE. CgHigJN'Og ; or C8Hi3N(OH).COOH. (See also page 270.) Ecgonine is obtained, together with benzoic acid and methyl alcohol, by heating cocaine with concentrated liydrochloric acid to 100° in sealed tubes (page 272).^ Also, when cocaine or its hydrochloride is heated with 20 parts of water and 10 of baryta to 120° in sealed tubes, it is decomposed according to the equation : — C17H21NO4 + 2H2O = C^HgOg + CgHi.NOg + CH,0 The actual products are methyl alcohol, barium benzoate, and a com- pound of barium benzoate with the barium compound of ecgonine, (2B8i{CgH^^'NO^\4-Ba{OBz\-\-xK^OX which forms slender pris- matic needles, very soluble in water and alcohol, but only slightly soluble in ether. This compound is a convenient source of ecgonine. On subjecting it to dry distillation it yields an isatr opine, the chloroplatinate of which forms bulky, orange- red, deliquescent crystals containing (C8Hj5NO)2H2PtClg. Ecgonine crystallises from absolute alcohol in monoclinic prisms containing 1 aqua, which melt at 198°; or, after drying at 140° to expel the water of crystallisation, at 205°. Ecgonine is very soluble in water, sparingly in absolute alcohol, and insoluble in ether. It has a slight bitter-sweet taste. When ecgonine is heated with moderately strong sulphuric acid, neither carbonic oxide nor formic acid is formed, but a base is produced which bears the same relation to ecgonine that ether bears to alcohol. It unites both with acids and bases. C. E. Merck (Ber., xix. 3002) states that ecgonine, when distilled with nearly dry barium hydroxide, yields methylamine and not ethylamine as one of the products, thus agreeing with the behaviour of tropine when similarly treated. When ecgonine (or anhydro-ecgonine) is oxidised with potas- sium permanganate, or nitric acid, succinic acid is formed (E i n- ^ Liebermann and Giesel obtain ecgonine on a lar^e scale by boiling the amorphous base obtained in the manufacture of cocaine for about an hour with hydrochloric acid. The filtered solution is evaporated to dryness, the residue treated with a little alcohol to remove impurities, and the residual ecgonine hydrochloride decomposed by sodium carbonate, the liberated base being recrystallised from alcohol. 284 BASES ALLIED TO COCAINE. horn, Ber., xxi. 47), a fact which shows tliat the side-chain in the molecule of ecgonine must be either in the a- or /3-position. Ecgonine contains a carboxyl-group, and hence behaves at once as an acid and a base. It has a neutral reaction, but reacts with alkalies to form gummy compounds of faint alkaline reaction, ■which crystallise with difficulty and are very soluble in water and alcohol. Ecgonine liydrocJdoride, CgHjgNOgjHCl, forms triclinic tables, difficultly soluble in alcohol and melting at 246° C. B^HgPtCle, after drying at 140°, melts at 226°. It is extremely soluble in water, and is deposited in orange-red prisms on adding excess of alcohol to its aqueous solution. BHAuCl^ is a greenish yellow, gummy substance, very soluble in water and alcohol. "With iodised potassium iodide, ecgonine yields a reddish brown precipitate, rapidly changing to reddish yellow, microscopic tables or prisms. In dilute solutions the precipitate is formed only after concentration. In the animal system, cocaine is converted into ecgonine, which may be detected in the urine by this test. Anhydro-ecgonine. C9H13XO2; or CgNH^Me.CHiCH.COOH. This base is formed by the action of phosphorus oxy chloride or pentachloride on ecgonine, or by heating cocaine for eight hours to 140° with glacial acetic acid which has been saturated with hydro- chloric acid gas. It forms colourless crystals melting at 235", soluble in water and alcohol, but insoluble in ether, chloroform, benzene and petroleum spirit.^ When anhydro-ecgonine is heated with water to 150°, methylamine is liberated. It combines directly with bromine to form a base containing CgHjgBrgNOg, the hydrochloride of which melts at 184°. The salts of anhydro- ecgonine are crystallisable. BHCl crystallises from absolute alcohol in white needles melting at 240°-241°. Bases allied to Cocaine. Dextro-cocaine. CiyHgiNO^. Einhorn and Marquardt {Ber., xxiii. 469, 979) have found that by warming with aqueous potash for twenty -four hours, ecgonine is converted into a base which differs from ordinary ecgonine in being much less soluble in absolute alcohol, and having a much higher melting-point (254°) ; but especially in being dextro-rotatory. From this dextro -ecgonine a synthetic dextro-cocaine may be prepared as a colourless oil, which solidifies on standing, and is readily soluble in ether, alcohol, benzene, and petroleum spirit. Dextro-cocaine may be obtained in crystals, melting at 43°-46°, ^ Hence it is best isolated by treating the solution of its hydrochloride with argentic oxide (compare page 20). It may be purified by precipitation from its alcoholic solution by ether. BASES ALLIED TO COCAINE. 285 by treating its solution with a crystal of benzoyl-dextroecgonine ethyl- ester. The salts of dextro-cocaine crystallise well. BHCl is much more difficultly soluble than the hydrochloride of ordinary cocaine, and melts at 205° instead of 181°'5. BHNO3 is especially characteristic. 100 parts of water at 20° C. dissolve 1'55 parts of the nitrate, which is precipitated in crystals on adding nitric acid to solutions of other salts of the base. This behaviour distinguishes dextro- cocaine from ordinary cocaine. BgHgPtClg crystallises from hot water in yellowish needles. BHAuCl^ crystallises from dilute alcohol in needles melting at 148°. Dextro-cocaine was found to resemble ordinary cocaine in its physiological effects, except that local ansesthetic action commenced more rapidly, and disappeared in a shorter time. With chromic acid, potassium permanganate, and auric chloride, dextro-cocaine behaves like cocaine. CocETHYLiNE, HoMococAiNB, or Beuzoyl-ecgonine ethyl-ester, CjgHggXO^, is the higher homologue of cocaine, which base it closely resembles. It is prepared by heating benzoyl-ecgonine with ethyl iodide and alcohol for eight hours at 100°. It crystallises from alcohol in vitreous prisms melting at 108°-109°, and is also soluble in ether but nearly insoluble in water. The cliloroplatinate forms bright yellow, rhombic plates, resembling the cocaine salt but more crystalline. Physiologically, homococaine is similar in its effects to cocaine, but is weaker and less toxic, and does not appear to be mydriatic. The higher homologues of cocethyline, containing propyl and isobutyl groups, have been prepared by similar means; and also by passing hydrochloric acid gas into a solution of benzoyl- ecgonine in the corresponding alcohol, CiNNAMYL-cocAiNE. CjgHggNO^ ; or C9Hi3(CH3)(C9H70)N03 . This base has been obtained synthetically by passing dry hydro- chloric gas into a solution of cinnamyl-ecgonine (prepared by heat- ing ecgonine with cinnamic anhydride and water). It forms large colourless crystals melting at 121°, and is almost insoluble in water, but readily soluble in alcohol, ether, &c. When boiled with hydrochloric acid it is decomposed readily and quantitatively into cinnamic acid, ecgonine, and methyl alcohol. BHCl is precipitated as an oil which solidifies after a time on adding a large volume of ether to a strong acidulated solution of the salt in alcohol. BgHgPtClg crystallises in microscopic needles melting at 217^. When treated with a cold solution of potassium permanganate cinnamyl-cocaine and its salts immediately evolve a strong odour of benzaldehyde (bitter-almond oil). 286 COCAMINE. Cinnamyl-cocaine has been proved to occur naturally in coca leaves from various sources. Paul and C o w n 1 e y (Pharm. Jour.^ [3], XX. 165) examined a sample of leaves containing 1*75 per cent, of total alkaloid, nearly 0*5 per cent, being crystallisable from petroleum spirit, but which, nevertheless, contained very little real cocaine. On oxidation by permanganate the crystallisable alkaloid yielded abundance of benzaldehyde, and in other respects corresponded with cinnamyl-cocaine (methyl cinnamyl-ecgonine). CocAMiNE. a-Truxilline. C38H4gN20g+H20. This base is con- tained in notable quantity in Truxillo coca leaves. Hesse found 0*6 per cent, in leaves of a different kind, and states that East Indian coca leaves, and especially those from Java, contain cocamine in con- siderable amount. Liebermann regards cocamine as identical with the base originally described by him asy-isatropyl cocaine, and afterwards asa-truxilline; but Hesse contends that Lieber- mann's product was a mixture, of which cocamine was a leading constituent.^ Cocamine has a bitter taste. Hesse and Stockman found its physiological effect to be similar to that of cocaine, but somewhat weaker, and its anaesthetic action especially weak. On the other hand, G. Falkson alludes to y-isatropylcocaine (cocamine) as a " deadly alkaloid," and Liebermann describes it as a heart-poison which does not produce anaesthesia. To its presence as an impurity, the occasionally highly toxic effects of commercial cocaine are not improbably due. Cocamine is precipitated by caustic alkalies and ammonia from solutions of its salts, and after exposure at the ordinary tempera- ture in a desiccator retains one molecule of water. It is readily soluble in alcohol, ether, benzene and chloroform, but differs from cocaine in being very sparingly soluble in petroleum spirit. Neither the free base nor its salts have been obtained crystallised. Repeated solution in hydrochloric acid and reprecipitation by soda was the process employed by Liebermann to purify the cocamine from the co-occurring isococamine (/8-truxilline), which is also bitter, and produces numbness of the tongue very slowly by reason of its sparing solubility. Both cocamine and its isomeride have been obtained syntheti- cally. When hydrolysed by mineral acids they yield ecgonine, methyl alcohol, and cocaic and isococaic acids respectively. Cocaic Acid, CgHgOg, or C^gH^gO^, called by Liebermann y-isa- tropic acid or a-truxillic acid, is produced by boiling ^ The composition of cocamine and its allies has formed the subject of an embittered controversy between Liebermann and Hesse {PJutrm. Jour., [3], xxi. 1109, 11'29; xxii. 61, 101). BENZOYL- PSEUDOTRO PINE. 287 cocamiiie with hydrochloric acid. The isomeric isococaic acid (^-isatropic or /5-truxillic acid) is the similar product from iso- cocamine. Cocaic acid melts at 274°, is tasteless and odourless, insoluble in water, and nearly insoluble in ether, from which, however, it crystallises in forms resembling benzoic acid. Isococaic (/3-truxillic) acid melts at 206°. Both cocaic and isococaic acids yield cinnamic acid and other products on distillation. Benzoyl-pseudotropine, CgH^^NO-CyHgO, is a base isolated by G i e s e 1 from a narrow-leaved coca plant cultivated in Java [Ber.j xxiv. 2336). It somewhat resem])les dextrococaine, but is opti- cally inactive, and differs from other coca-bases in not yielding methyl alcohol on hydrolysis ; for, when heated with hydrochloric acid under a reflux condenser for some hours, it is completely decomposed into benzoic acid and pseudotropine, CgHjgNO (see page 247). In this respect the base resembles atropine and the other tropeines.^ Benzoyl-pseudotropine is obtained as a milky precipitate which does not become crystalline on adding sodium carbonate to the solution of one of its salts. The base may be extracted by ether, and on evaporating the solution is obtained as an oil which, when quite dry, solidifies in radiating crystals melting at 49° C. It has a strong alkaline reaction, and is easily soluble in alcohol, ether, chloroform, benzene and petroleum spirit. BHCl, obtained by passing hydrochloric acid gas into an ethereal solution of the base, crystallises in white needles melting at 271°. The solution gives a bulky crystalline precipitate with mercuric chloride. BgHgPtClg is a flesh-coloured precipitate, insoluble in hot water, alcohol and ether. BHAuCl^ crystallises from water in sparingly soluble yellow needles, melting at 208°. The picrate forms fine yellow needles, difficultly soluble in water. With potassium bichromate, benzoyl-pseudotropine yields a crystalline precipitate, instead of an oily one like cocaine and dextrococaine. Amorphous Bases of Coca. In isolating cocaine there is found in the mother-liquors a variable quantity of a basic substance commonly known as "amorphous cocaine," while the names cocaicine and cocainoidine have also been applied to it. Amorphous cocaine is described by K Stockman {Pharm. Jour., [3], xvii. 861) as ranging in colour from dark yellow to dark brown, and consistence from that of treacle to a sticky tenacious solid, having a peculiar ^ Liebreich finds that benzoyl-pseudotropine introduced into the eyes of rabbits occasions strong local ansesthesia and a slight enlargement of the pupil, in this respect acting more like cocaine than atropine. 288 AMORPHOUS BASES OF COCA. smell resembling that of nicotine, and a bitter and aromatic taste. Stockman concludes that "amorphous cocaine" is in reality a solution of ordinary crystalline cocaine in h y g r i n e, the liquid alkaloid said to have been found in coca leaves by Lassen. The amorphous alkaloid is extracted from the coca in greater or less amount by the processes now employed by manufacturers, and its presence is considered by Stockman to account for certain disagreeable effects resulting from the employment of cocaine con- taining the impurity. Thus if the hydrochloride of the impure alkaloid be used to produce anaesthesia of the conjunctiva con- siderable irritation ensues. W. C. Howard {Pharm. Jour.^ [3], xviii. 71) to a certain extent agrees with Stockman's view as to the nature of amorphous cocaine. He found that when the solution of the bases of coca in hydrochloric acid was completely precipitated with platinic chloride, and the liquid filtered after standing over-night, the mixed platinum salts obtained were amorphous or semi-crystalline, and somewhat light in colour. When the precipitate was washed with a large quantity of water at a temperature not exceeding 80° C, the cocaine chloroplatinate dissolved, and the alkaloid could be obtained therefrom in a crystalline state. The fraction of the platinum salt insoluble in water when decomposed by sulphuretted hydrogen, and extracted with ammonia and ether, left on evapo- rating the ether a liquid base which thickened considerably on keeping, but in which no crystals appeared even after a week. It had an intensely bitter taste, formed an uncrystallisable hydrochloride, and a chloroplatinate containing 18'5 per cent, of platinum (against 19'3 per cent, in the cocaine salt)^ and not affected by hot water, all which characters distinguish the base from the description of h y g r i n e given by L o s s e n {Annal. der Pharm., cxxi. 374). 0. Hesse states that when working on the bases from the broad-leaved coca, separating the cocaine as hydrochlorate "by a special process," and ascertaining the absence of cocamine, the residual mixture was dissolved in dilute hydrochloric acid and the solution treated with ammonia in excess, this process of solution and reprecipitation being repeated until the precipitate dissolved in hydrochloric acid gave a solution which showed no fluorescence on dilution with water, thus proving its freedom from hygrine. The precipitate, after being further washed with water at 80° C, gave a melted mass which was spread on glass plates and dried at ^ Hesse {Pharm. Jour.^ [3], xviii. 71, 437) considers that Howard's platinum salt was liydrated, being in reality the chloroplatinate of an amor- phous base isomeric with cocaine. HYGRINE. 289 60°, by which means it was obtained in transparent, brittle, hygro- scopic laminae which were nearly insoluble in water and alkaline liquids, but dissolved readily in alcohol, ether, chloroform, benzene and petroleum .spirit. The solution was alkaline to litmus, but without effect on phenolphthalein {Pharm. Jour.^ [3], xviii. 71, 437). When boiled with alcoholic baryta, or heated in a sealed tube with hydrochloric acid, the amorphous base yields benzoic acid, and another product not yet identified. From a later investigation {ihid.,x\x. 867), Hesse concludes that the amorphous bases from true coca consist chiefly of benzoyl com- pounds of an oily non-volatile base, together with some cocamine; while, on the contrary, those obtained from Truxillo leaves consist essentially of cocamine, and the cinnamyl compounds of the before- mentioned oily base ; and the cocamine is in each case accompanied by a base containing Hg less than cocamine. A specimen of the amorphous base from coca examined by B. H. Paul {Pharm. Jour.^ xviii. 784) is described by him as being pale yellow, and of the consistence of thick Canada balsam. It had a faint odour at once suggestive of benzoin and butyric acid, and a distinctly bitter taste, but produced no anaesthetic effect on the tongue until after the lapse of some minutes, and then very slight compared with that produced by cocaine. Hygrine. Under this name several bases have been described, which were either impure or actually dissimilar. The name was first applied byLossen to a liquid volatile base which has not since been obtained. The hygrine of 0. Hesse {Pharm. Jour., [3], xviii. 438) is best prepared from the mother-liquor obtained in the preparation of " cocaidine " from amorphous cocaine. This is treated with caustic soda and ether, the ethereal solution separated and evaporated, and the residue distilled with water. The hygrine passes into the distillate, which is faintly acidified by hydrochloric acid, evaporated to dryness, and the residue treated with caustic soda and ether. The ether leaves on evaporation a brown oily residue, which, on treatment with dilute acetic acid, deposits a brown smeary mass, which is filtered off, the solution again treated with caustic soda and ether, and the ether evapo- rated. Hygrine thus obtained is a yellowish oily substance having an odour suggestive of that of quinoline. It has a slight burning taste, and a strong alkaline reaction on litmus, but does not alter phenol- phthalein. It is but little soluble in water or solution of caustic soda, but dissolves readily in alcohol, ether and chloroform. Hygrine volatilises with steam, and at a higher temperature may be distilled alone. VOL. III. PART II. T 290 HYGRINE. BHCl is crystallisable. Its dilute aqueous solution exhibits a marked fluorescence, not perceptible in a concentrated solution, and destroyed by sodium chloride and other substances. An aqueous solution of hygrine hydrochloride becomes milky on addition of caustic soda, owing to the separation of the free base in minute oily globules, which aggregate after a time. Hesse attributes to hygrine the formula C]L2^i3-^ ^^^ ^^® constitution of a trimethylquinoline, but Liebermann regards it as a mixture of oxygenated bases, which may be separated by fractional distillation. The most volatile boils at 193°— 195°, and has the formula CgHigNO, but is not identical with tropine (page 246). The less volatile portion of hygrine appears to contain C-^^Bi^^N^^, and cannot be distilled unchanged at the ordinary pressure. Neither of these bases is affected by heating to 120° with concentrated hydrochloric acid (Ber., xxii. 675). Hesse points out that hygrine probably does not pre-exist in coca leaves, but is a product of decomposition. He states that when sound coca leaves are moistened with ammonia, shaken with ether, and the ether treated with dilute hydrochloric acid, the acid liquid on dilution at first shows no fluorescence, but after a time exhibits this character distinctly. R. Stockman {Pharm. Jour., [3], xviii. 701) states that hygrine exists in coca leaves in very minute quantity only, and some manufacturers never meet with it. He found it in cocaine mother- liquors given him by Messrs Howard & Sons, and notably in the alcoholic tincture of freah coca leaves. Stockman finds hygrine to distil very imperfectly with steam in presence of cocaine.^ The whole of the statements respecting hygrine require con- firmation. Stockman describes hygrine as a brown oily liquid with a char- acteristic smell. A drop placed on the tongue causes a burning sensation. Frogs were killed by the subcutaneous injection of hygrine mixed with water. There was considerable irritation at the place of injection, while the muscles all over the body, the bowels, and the serous membranes were studded with numerous minute haemorrhages. Coca Leaves. The coca leaves occurring in commerce are chiefly of two kinds, ^ The treatment is stated to have decomposed the cocaine present, some benzoic acid passing over with the hygrine. It seems probable that a difficultly volatile or non-volatile benzoate of hygrine was formed. A better result would probably have been obtained by adding an alkali to the contents of the retort. COCA LEAVES. 291 the one being obtained from Erytliroxylon coca} which was the original trade-product, and the other, which is of more recent importation, derived from Jamaica and St Lucia. Coca leaves contain, in addition to the ordinary plant-constituents and the characteristic alkaloids, cocatannic acid. CooATANNic Acid (C. J. H. Warden, Pharm. Jour., [3], xviii. 985) has the probable composition Cj^H^gOg. It forms a sulphur-yellow powder, which appears under the microscope in filiform crystals interlaced in masses. It melts at 189°-191° to a deep red liquid, and is only slightly soluble in cold water, cold absolute alcohol, ether and chloroform. In hot water it dissolves more readily, and rather freely in boiling absolute alcohol. A hot aqueous solution of cocatannic acid has an acid reaction. It yields no reaction with ferrous salts (according to some observers, green), but with ferric gives a dark green coloration, and reduces silver nitrate slowly in the cold and immediately on heating, but not Fehling's solution. It does not precipitate gelatin. The alco- holic solution gives, with alcoholic lead acetate, a precipitate varying from yellow to orange-red. When heated with hydro- chloric acid to 100°, cocatannic acid yields a glucose and a phlobaphene. The products of potash-fusion do not appear to be characteristic. They are said to include butyric and traces of benzoic acid. C. J. H. Warden (Phami. Jour., [3], xviii. 1010, 1027) has observed that coca leaves which are rich in cocatannic acid also contain much alkaloid, and suggests, with much probability, that the cocaine and allied alkaloids of coca leaves exist in combina- tion with cocatannic acid. Warden, in nine specimens of the dry leaves from plants grown in different parts of India, found from 6'36 to 12'64 per cent, of ash (average 8*85 per cent.), and from 0-358 to 1-671 per cent, of "crude alkaloid" (average 0-982 per cent.). Warden did not succeed in obtaining a crystalline alkaloid from Indian coca, but does not consider the non-crystalline character detracts from its physiological activity Q). A. G. Howard (Pharm. Jour., [3], xix. 569) has published analyses of a large number of coca leaves from different sources. His results show that while Erythroxylon coca yields about f per cent, of alkaloid, the proportion obtainable from most other species of Erythroxylon is extremely insignificant, and in some cases the alkaloid is wholly absent. In Brazil alone there are upwards of eighty species of Erythroxylon. ^ The coca plant is a small shrub from 4 to 6 feet in height, growing and largely cultivated in Peru and Bolivia, and, to some extent, in Brazil and the Argentine Republic. 292 COCA LEAVES. H. T. Pf eif f er (Ohem. Zeit, xi. 783, 818; Jour. Soc. Cliem. Ind.j vi. 561) has described the following process of manufactur- ing crude cocaine hydrochloride direct from coca leaves : — The disintegrated leaves are digested in closed vessels at 70° C, for two hours, with a very weak solution of caustic soda and petroleum boiling between 200°-250°. The mass is filtered, pressed while still tepid, and the filtrate allowed to stand until the petroleum has completely separated from the aqueous liquid. The former is then drawn off and carefully neutralised with very weak hydrochloric acid, when a bulky, white precipitate of cocaine hydrochloride is obtained, together with an aqueous liquid from which a further quantity of the salt can be recovered by evaporation. The dried product contains about 75 per cent, of real alkaloid, besides traces of " hygrine," gum, and other matters. A repetition of the process proved that the whole of the alkaloid was removed by a single treatment. The soda cannot be substituted by lime, nor the hydrochloric acid by other acid. Assay of Coca Leaves. Pfeiffer employs a similar process for the assay of coca leaves, 100 grammes of which should be digested in a flask with 400 c.c. of water, 60 c.c. of 10 per cent, soda solution, and 250 c.c. of petroleum. The mixture is kept warm for some hours and shaken occasionally, then strained, the residue pressed, and the filtrate allowed to separate. The aqueous liquid is tapped off, and the oily layer titrated with ^ hydrochloric acid. The number of c.c. required, multiplied by 0042, gives the percentage of cocaine in the sample. The fresh leaves contain from 0'3 to 0'6 per cent., but this proportion decreases considerably if the leaves have been stored for any length of time before being worked up. For the assay of coca, v. d. Marck (Jour. Pliarm., [5], xx. 500; Analyst, xiv. 115), after a trial of various processes, recommends that 50 grammes of the leaves should be mixed with 20 grammes of calcined magnesia and moistened with a little water, dried at 60°, and the mixture exhausted with ether. The ether is distilled off, and the residue treated with 30 c.c. of 2 per cent, hydrochloric acid. The solution is filtered, and repeatedly shaken with ether to remove colouring-matters. Ammonia is then added, and the cocaine extracted by shaking three times with 25 c.c. of ether. After standing for a short time over some fragments of calcium chloride, the ether is evaporated, and the residual alkaloid weighed. For the estimation of the cocaine in coca leaves, A. B. Lyons {Jour. Pharm.t [5], xiii. 197) recommends that the finely- ASSAY OF COCA LEAVES. 293 powdered leaves should be macerated for twenty-four hours with eight times their weight of a mixture of 95 volumes of ether with 5 of ammonia. From an aliquot part of this liquid the alkaloid is extracted by agitation with acidulated water, the ether separated, and the alkaloid liberated from the aqueous liquid by means of ammonia and again extracted with ether, which is then evaporated to dryness and the cocaine weighed. The associated bases, being soluble in water and insoluble in ether, remain in the ammoniacal liquid. Lyons states that coca leaves do not contain more than 0"8 per cent, of cocaine, and sometimes the proportion is as low as 0'15 per cent. The leaves rapidly deteriorate in value, so that in six months they are practically worthless. The product from deteriorated leaves is always more or less coloured, and very little of it is crystallisable ; while that from good leaves is almost colourless, and easily crystallises. M. Bignon (Lima)^ states that coca leaves dried in damp weather, with frequent turning, and sheltered from dew and moisture, yield easily 0*8 per cent, of alkaloid, and the finer sorts can give I'O per cent, and upwards under exceptional circum- stances. Coca leaves dried in damp weather, or pressed into sacks before being completely dried, undergo a gradual f«rment which ends in the complete destruction of the cocaine. OPIUM ALKALOIDS. Opium, the nature and characters of which are described at length on page 332, is remarkable for the large number of nitro- genised organic principles contained in it. At least nineteen alkaloids have been isolated from opium, and the list is probably still incomplete. Most of these bodies have well-defined basic pro- perties, and the majority are poisonous. Some of them, as mor- phine and narcotine, occur in opium in considerable quantity, but the greater number are present in very small proportion, and are entirely absent from some samples. The following table exhibits the leading characters of the nitro- genised principles which have been recognised in opium. In some cases the basic character is very feebly marked, while certain of the alkaloids {e.g., pseudomorphine, oxynarcotine) are probably decomposition-products. ^ Pharm. Jour., [3], xvi. 267; xvii. 606. Bignon states that the Indian never chews coca leaves alone ; but mixes them with ashes and lime, whereby the alkaloid is liberated, and thus obtains the anaesthetic properties and numbing effect upon the mucous membrane of the stomach which he desires. 294 OPIUM BASES. S •' 2 „• o C o o 5 2 -^ 6^ o a I fe .2 ;S !zi t> o S « -J .2 •" iJ -S o o H H ^ a 125 pgcE'poopC'oo'sC'S© tL ^ s 5 5> ^ 5 ^ K) Ht t-3 HH : ^ « : H? boO lO O) t> o> o ea eo N l§ S (N »0 00 O 05 o r-l O i-H rj" t» t- t~ CO 00 00 00 00 eo lo (M If a2 £! ^' WWWHWWhW 2 I W c l'& PLH P^H H M W lf> w Jp t^ UU VJ C^ -^ -^ '^^ "H" X- -J -• — _.— - !.-_ — _ oooooooooooocoo M M o !2i sn !z; §5 S S W Ph w 25 £2 £2 o o o S .a 's ^ a a -a -2 .3 o P5 12; § i -§ ^ cs IS o ^3 »:3 o ^ SAXGUINARINE. 295 In addition to the alkaloids in the above list, deuteropine, opionine, papaverosine, and porphyroxine (page 330) have been described, but their existence as individuals is very doubtful. "With one or two exceptions, the alkaloids of opium are strictly peculiar to Papaver somniferum ; while, on the other hand, the poisonous alkaloid sanguinarine, which is present in aU other papaveraceous plants, does not appear to exist in Papaver.^ Indeed, with the exception of pro t opine, which is probably identical with the interesting alkaloid macleyine, CgoHigNOg, obtained by Eykman (Tear-jBooA; Pharm., 1882, p. 33) from ^ Sangtjinarine, C17H15NO4, is best prepared from the root of Sanguinaria Canadensis (Year-Book Pharm., 1871, 310 ; 1875, 256 ; 1879, 201). The root is exhausted with water acidulated with acetic acid, the solution precipitated by ammonia, the precipitate dried and exhausted with ether, and the ethereal solution treated with hydrochloric acid gas, which throws down the hydro- chloride of sanguinarine (RHCl + HgO) as a scarlet precipitate, which may be purified by solution in hot water and repetition of the treatment with ammonia, ether, &c. The free alkaloid melts at 160°, and crystallises from hot alcohol in small white needles having an acrid, burning taste. Sanguinarine is a powerful narcotic poison ; the powder causes sneezing. It is insoluble in water, but soluble in ether, chloroform, amylic alcohol, benzene and petroleum spirit. The solutions exhibit a strong violet fluorescence without absorption-bands, and are optically inactive. The salts of sanguinarine are orange-red, and hence the free alkaloid is reddened by the fumes of hydrochloric acid. The precipitation of the bright red hydrochloride from the ethereal solution of the alkaloid, as above described, is a highly characteristic reaction. Alcoholic sulphuric acid behaves similarly. Aqueous solutions of sanguinarine salts exhibit a violet fluorescence, and are precipitated white by ammonia and bright red by potassio-iodide of mercury. BaHgPtClg + HgO forms a bright orange precipitate, very slightly soluble in water. Chelerythrinr, which occurs inchelidonium and several other plants, is regarded by Schiel as identical with sanguinarine, but E. Schmidt agrees with Naschold that the more probable formula is C19H17NO4. Chelidonine, C20H19NO5 + HgO, is the principal alkaloid of the twelve said to exist in the root of the common celandine {C'helidonium majus), and occurs in several other plants in association with sanguinarine or chelerythrine (or both). Chelidonine forms colourless monoclinic crystals melting at 130°, soluble in alcohol, but insoluble in water and but slightly soluble in ether. The salts of chelidonine are colourless, and have a very acrid and bitter taste. The hydrochloride forms fine crystals which require fully 300 parts of cold water for solution, which character may be used for isolating the alkaloid. Chelidonine is a tertiary base, and contains no methoxyl-group. With sugar and sulphuric acid it gives a violet coloration. (See E. Schmidt, Pharm. Zeit, 1889, 58.) Several other alkaloids besides those already named have been detected in Chelidoniv/m majus, among them being a- and /3-homocheliHonine, 296 OPIUM BASES. Macleya cordata (a poisonous Japanese plant), none of the nitro- genised substances found in opium appear to be identical with any of those extracted from other plants of the family.^ Constitution of Opium Bases. Some of the opium bases are isomeric, while others are homo- logous, or else differ from each other by the increments C2H2, CO, Hg, HO, or multiples of these. The tendency to combine with each other to form stable crystal- line compounds, which renders bhe isolation and study of the cinchona bases so difficult (see Homoquinine), does not seem to exist in the case of the opium alkaloids. The chemical constitution of the opium alkaloids is not yet thoroughly understood, but they have been proved to be derivatives of quinoline, and in some cases further advances have recently been made. Morphine (compare page 167) has been proved by the researches of Wright, Grimaux, Hesse, Skraup, Knorr, and others to contain two hydroxy 1-groups, one of which has a phenolic and the other an alcoholic function. The first of these can be readily replaced by alkyl and acid radicals, forming codeine, acetylmorphine, &c. The second hydroxyl-group may also be replaced,^ with forma- tion of bodies of the type of methocodeine,^ which differs from thebaine by Hg, thus : — Morphine, . . C,7Hj7(OH)NO.OH Codeine, . . Ci7Hi7(OH)NO.OCH3 Methocodeine, . . Ci7Hi7(OCH3)NO.OCH35 Thebaine, . . Ci7Hi5(OCH3)NO.OCH3 Ci9Hi5(OCH3)2N03, and (probably) protopine (F. Selle, Arch. Pharm., ccxxviii. 441). Stylophorine, the alkaloid of Stylophoron diphyllum, is apparently identical with chelidonine. Clielerythrine is stated to exist in the root of the yellow sea-poppy, Glaucewm luteum, together with glaucine and glaucopicrine, both of which form crystallisable salts (Pro bat, Annal d. Chemie, xxxi. 241). Porphyroxine (a body distinct from Merck's alleged opium base) and p u c c i n e are said to exist in san- guinaria root ; and two alkaloids have been found in Eschscholtzia Californica^ one of which is probably methyl-chelidonine. The alleged presence of morphine has not been confirmed. Of all these bases, only sanguinarine and chelido- nine have been fairly well studied ; while the data respecting the others do not suffice to characterise them. ^ A base identical with, or similar to, narcotine was isolated by T. and H. Smith from the fresh juice of the roots of Aconitum Napellus^ but other observers have not confirmed this result. 2 See footnote ^ on next page. ^ It is not certain that methocodeine has the constitution ascribed to it in CONSTITUTION OF MORPHINE. ^97 The poisonous characters of morphine, which are both narcotic and tetanic, are shared qualitatively by derivatives in which only the hydrogen of the hydroxyl is replaced, as in codeine, ethyl- morphine, amyl-morphine, mono- and di-acetyl-morphine, benzoyl- morphine^ and morphinyl-sulphonic acid. But when further substi- tution takes place, as in chlorocodeine and methocodeine (page 324), the product is not merely a nerve-poison, but a muscle-poison. Apomorphine, the constitution of which is probably not simply that of an anhydromorphine, is a muscle-poison analogous to methocodeine.2 L. Knorr {Berichte, xxii. 181, 1113) considers that morphine contains a reduced phenanthrene-nucleus and a methyl-group united with the nitrogen, and represents it by the following formula : — OH / **CH I Cflg rr I CH» \ CH I k It remains undecided whether the alcohol-hydroxyl is connected with carbon atom * or **■. Skraup and Wiegmann (Monatsh., x. 110) have shown that this formula requires modification ; for on heating morphine to a high temperature with alcoholic potash, aphenoloid body and ethyl-methylamine are formed, which fact proves that the text. It is not improbable that the alcoholic hydroxyl remains intact, the second methyl-group being introduced into the body of the morphine molecule, thus :— Ci7Hi6(CH3)NO(OH).OCH3. ^ By heating anhydrous morphine to 100°-110° with excess of benzoic chloride a dibenzoyl-derivative is obtained, and diacetylmorphine may be obtained in a similar manner. These compounds were first obtained by C. R. Alder Wright {Jour. Chem. Soc.,xxyu. i.631). When two acetyl- groups have been introduced into morphine no further substitution can be elfected — a fact which confirms the view that the morphine molecule contains only two hydroxyl-groups (see Danckwortt, Arch. Pharm. , ccxxviii. 672). 2 When treated with excess of acetyl chloride, apomorphine yields only a monoacetyl-derivative. Hence, probably, only one (the phenylic) hydroxyl atom exists in apomorphine, the second (alcoholic) having been eliminated during its formation from morphine. 298 CONSTITUTION OF OPIUM BASES. in morphine both an ethyl and a methyl group are directly united to the nitrogen atom. Pseudomorphine was formerly represented by the formula CiyH^^gNO^. Hesse found that the base contained a molecule of water which, when driven off, was recovered very rapidly. He therefore preferred the formula Ci^^Hj^NOg ; but more recently has abandoned this for Ci7Hj^8N03, or preferably Cg^HggNgOg, the base having the constitution of an oxydimorphine.^ On the other hand, M. P. Cazeneuve {Compt. Rend., 1891, p. 805) has obtained a violet colouring matter of definite composition by acting on morphine with paranitroso-dimethylaniline (page 75). This dye appears to be an i n d a m i n e, analogous in constitution to Bind- schedler's green; whereas, if pseudomorphine were derived from two molecules of morphine, the colouring matter would have contained two morphine residues, and had the constitution ofasafranine (Part I. page 252). Combination is not effected by means of the hydroxyl-group having a phenolic function, since codeine yields a similar dye. Narcotine, CggHggNOy, contains three methyl-groups (besides that connected with the nitrogen), the first two of which may be suc- cessively removed by heating the alkaloid with strong hydrochloric acid, while by heating with fuming hydriodic acid the third group may be removed, nornarcotine, CigH^yNOy, being produced together with methyliodide. When narcotine is heated with water under pressure at 150°, it is split up in the first place with formation of opianic acid and hydrocotarnine (page 325) : — The two products subsequently react more or less completely to form m e c n i n and cotarnine, thus : — CioHi„0,+Ci2Hi,N03 = Ci„Hj„0,+Cj2H,3N03+H20 (compare page 161). Opianic acid, C^^^qO^ (compare page 203), forms delicate whit© crystals. It is reduced to meconin (page 335) by nascent hydro- gen, and by oxidation with dilute chromic acid mixture yields hemipinic acid, G-i^ifi^. By the action of soda-lime, opianic acid yields methyl-vanillin, CgHj^Og, which when boiled ^ On heating pseudomorphine with acetyl chloride, a tetracetyl-derivative is produced ; a fact which indicates that the four hydroxyl-groups are still intact, and that the hydrogen atoms lost in the formation from morphine must have been united with carbon. CONSTITUTION OF NARCOTINE. 299 with hydrochloric acid gives vanillin, CgHgOg (Part I. page 62 ; see also Dott, Pharm. Jour., [3], xiv. 641).^ Cotarnine, CjgHjgNOg, is contained in the mother-liquor from which the meconin has crystallised. It forms a very soluble, yellow, bitter substance. It is a fairly strong base, soluble in ammonia and fusible in boiling water. When gently heated with very dilute nitric acid it yields methylamine nitrate and cotarnic acid, a bibasic acid containing G^.^-^^^^. W. Eoser {Annalen, ccliv. 334, 359), from a careful considera- tion of the evidence, considers narcotine to contain the residues of opianic acid and hydrocotarnine, and expresses it by the following graphic formula. It is closely related to pajpaveriney both being derivatives of a benzyl-isoquinoline. 0CH3 A OCHo 00 OCHs OCH3 HO CH3)N CH2 O-CF2 OCH3 CH2 H Narcotine. CH3 Papaverine. OCHs OCHa W. Roser {Annalen, ccxlvii. 167) has obtained an isomer of narceine by treating narcotine methochloride in aqueous solution with caustic soda, when narcotine methyl-hydroxide is precipi- tated. On exposure to steam this changes into a base which is possibly identical with narceine, apparently in accordance with the equation :— C22H23lSr07,CH30H + 3H20 or perhaps the new base is an anhydro-narceine taining C^fi^^l^O^ZRJd. Narceine has been expressed by the constitutional formula fCO.OH C23H29NO„2H20 ; con- (Ci3H2„N04).CO.CeH2^ O.CH3 LO.CH, CgH^ rO.CHa O.CH, '2] CO. OH Leo. OH Henaipinic acid. rO.CHg 0.CH3 CO.H ICO.OH Opianic acid. C«H p„ I0.CH3 ^6^2 1 CO.H IH Methyl-vanillin. fO.CHg p TT 1 O.CH W^2i CO ICH Meconin. .}« 300 OPIUM ALKALOIDS. General Characters of Opium Bases. Morphine, codeine, thebaine, papaverine, narcotine and narceine are the most important of the alkaloids of opium. The opium alkaloids form a group of which all the members exert a more or less narcotic and tetanising action, but in very varying degree. Thus morphine is almost purely narcotic and thebaine almost purely tetanising in its action.^ Morphine, codeine and thebaine have strongly-marked basic characters. They are strongly alkaline to litmus, and afford stable salts.^ Papaverine, narcotine and narceine, on the contrary, are very weak bases (compare page 305). The free alkaloids of opium are generally but slightly soluble in water, but dissolve more readily in alcohol. In many instances the solutions of the free alkaloids are strongly alkaline to litmus. On the other hand, certain of them {e.g., morphine, narceine, laudanine) exhibit a distinct phenoloid character, and form definite compounds with the alkahes. The different behaviour of the opium bases to solvents affords a valuable means of distinguishing and separating them. They are precipitated from concentrated solu- tions of their salts by caustic alkalies and alkaline carbonates, some of the precipitates dissolving in excess of the reagent. Most of the opium alkaloids (except papaverine and laudanosine) have a IsBVO-rotatory action on polarised light, but the specific rotatory power varies so greatly with the solvent and the concentration of the solution that the fact has a very limited practical value. Many of the opium alkaloids furnish characteristic colour-reactions when treated with strong acids and oxidising agents, which, with observations of their melting-points, crystalline form, and behaviour with solvents, will suffice for the recognition of most of them when in an unmixed state. Their separation is described on page 305 et seq. Behaviour of Opium Bases with Solvents. The following table shows the recorded behaviour of the opium bases with solvents. The figures are the number of parts of the solvent required for the solution of one part of the alkaloid. Apomor- phine is not a natural constituent of opium, but is formed by the dehydration of morphine, and introduced into the table for con- venience of comparison. The figures are the number of parts of the solvent required for the solution of 1 part of alkaloid. ^ Thebaine appears to be the most poisonous of the leading alkaloids of opium. Papaverine appears to possess only very slight poisonous properties, if any. ^ Codeine is distinctly more strongly basic than morphine, and a method of determining the former alkaloid has been based on the fact (page 323). SOLUBILITIES OF OPIUM BASES. 301 g d J-g ^ : Sl1^"-t . . •§ .2 aj . >.3 . 3 ^ 1^^ 1 |g||§£.a : li 1 r i 3 «3 . a> 6 "So '^ 4s.>. i. 1 i >. f^ 1 1 mm ^3 tf 1 .5 : 02 00 "3 ^ ^ cs . ® §••2. t So I< ^ -3 J ill 1 || 1 51 1 |s 1 ^3 ^ It 3 ^ « >-.>^ . cj OJ >i >> ^ o 3 >?£ mU « <0>? -^•^3 3 % U^. 1 CO n 1 p""" .=* o s 3 1 n CO i • 5 ISO- 11 : : - Sg : : : : : : : : o : ^^ s^ S^ Sa ^3* ^ III- 0202 CQ illil .tf 1 1^ •s 5 ^ .& ^ » t^ . « i£ ©' 5 1 itllilillll QQ 03 EQ 02(25 MOO !d 3 a; i?5 III! §11 1 3 3 I 3 . 1— 8 , O •d>4 f^ o cS .» •^•3 eU ©05 i/J >fS 9) a • © >.^33 3 « >>. 23 ©3 © 3 3 > a^ •a S.Q fl rf 7" S 7? ? |1 |a^ 1 §111 l3^|s 11 1 -^ -^ B ^^3 ill a S^f^ » n "o 0-3 o^ © c ;= 1 O OT W l-Hl-( jgoJM MHI b 5 ;:< - 02 cc i 3 33 5 5S : : : 3 to © a . 1 !^" H5 1 8 : 1 3 : 3 ■ B M . . . . . . . . . . . . ^ ^ 1 o .9 < 3 . . . I llf s 1 II III e 1 2" *" « g © a ill © a ll 1 P^ K?i o © 5?; ©" "p. g .1 ll 302 COLOUR-REACTIONS OF OPIUM BASES. .2 • ^23:^2 -I n ^3 ■r o to c « !U «tD l« .2 =8 JH ^ C!^ o o 9 b. CQ O o o -J ,c >» "|2 tboj « .25-^ ^ to m 3 ^ 5 §-. O S !* . r-5 - O tB .2 a t*-? c c8 a ^'l' gill O Ch-S fc.,2i t-.;a j3 O ..-. >« a 2 «^ -_2 to to c3 o 'cl.3 ^ > tos o W)»§ Oaa. -3 to tCX3 o '•*d)S^«^.'5tO >CtO >>ai'"a >jpa rs aj.a 00 S ca.a °3 pg23 -5 c^ 35°.2c O a c3 COLOUR-KEACTIONS OF OPIUM BASES. 303 The solubility of opium bases, as of other substances, is much affected by the physical condition of the alkaloids, and to some extent by the manner of making the experiment. Colour-Reactions op Opium Bases. Several of the opium bases react in a more or less characteristic manner with potassium permanganate (see page 144). Many of the opium alkaloids give brilliant, and in some cases characteristic, colour-reactions with mineral acids, with or without the aid of heat and the addition of oxidising agents. The colours obtained vary somewhat with the mode of applying the test and with the oxidiser employed. The colours obtained are modified in a marked manner by very slight traces of oxidising agents in the sulphuric acid used, and hence this reagent should be scrupu- lously free from iron and oxides of nitrogen. E. K a u d e r re- commends that the purity of the sulphuric acid should be tested by codeine, which should give no colour even on heating, while in presence of the faintest trace of iron, such as may be taken up from long keeping in a bottle of common glass, a violet coloration is produced. The colour-reactions of the opium alkaloids are best observed in the manner described in detail on page 3 1 3 e^ seq. Many of the colour-reactions of the opium bases defy classification, and such of these as appear of value are de- scribed under the alkaloids to which they refer; but the table on page 302 shows many of the better-known reactions of the more important opium bases, according to the most reliable observers. If a trace of narceine be evaporated with dilute sulphuric acid at 100° C. a beautiful violet-red coloration appears as soon as the liquid is sufficiently concentrated ; changing to cherry-red by con- tinued heating. After cooling, the addition of a trace of nitric acid or a nitrite produces bluish violet streaks in the red liquid. The test, which is due to Plugge {Jour. Chem. Soc, lii. 870), is said to be very dehcate and characteristic. With traces of morphine, codeine, or papaverine the liquid remains quite colourless; with larger quantities of either of the two former bases a faint rose-red tint is obtained, with thebaine a greenish yellow to brown colour, and with narcotine a red to reddish brown. According to Serena (Analyst, x. 149), the following colour- reactions are produced on treating certain of the opium alkaloids successively with a few drops of concentrated sulphuric acid and a very small quantity of a dilute solution of ferric chloride, with the aid of slight heat. 304 COLOUR-REACTIONS OF OPIUM BASES. ' Alkaloid. With Sulphuric Acid. On adding Ferric Chloride. Apomorphine, Codeine, . Papaverine, Opionine, . Narceine, . Codamine, Not changed. light violet-red, deepened by heat (compare p. 322). Purplish red. No coloration. Coflfee-brown. Violet streaks at point of contact, the bluish green mass becoming light violet on heating. Sky-blue. Colourless ; on heating, violet. Green ; rapidly becoming deep-blue. Bluish green. Green-blue ; at 100", violet. The following table shows the colour-reactions observed by He s s e (Jour. Cliem. Soc, xxiv. 1064) when certain of the opium bases are treated with pure concentrated sulphuric acid, and with acid containing traces of oxide of iron or oxides of nitrogen. The reactions with ferric chloride are also shown. Alkaloid. With^mre Sulphuric Acid. With Acid containing Oxide of Iron. With Feme Chloride. At 20* C. At 150" C. At 20° C. At 150° C. Codeine, . Codamine, . Lanthopine, Laudanine, . Laudanosine, Protoplne, . Cryptopine, Hydrocotar- nine. Colourless. Colourless. Colourless. Very faint rose-red. Faint rose-red. Yellow, chang- ing to red and bluish red Yellow, chang- ing to violet.2 Yellow. Dirty green.i Dirty red- violet. Brownish yel- low. Deep red- violet. Deep red- violet. Dirty green- ish brown. Dirty green. Crimson - red, changing to dirty red- violet. Blue. Intense green- blue. .. Intense rose colour. Brownish - red (resembling cobalt ni- trate solu- tion). Deep violet. Deep violet. Dirty green. Deep violet. Green, chang- ing to deep violet. Green, chang- ing to deep violet. Dirty green- ish brown. Dirty green. Dirty red- violet. No reaction. Dark green. No reactions. Emerald-green.2 No reaction. No reaction. No reaction. ^ According to E. Kauder {Pharm. Jour., [3], xviii. 250), if the sulphuric acid be quite pure no coloration is yielded with codeine even on heating, but a blue colour is produced if traces of iron be present. Cryptopine dissolves with violet colour, changing to deep blue, and fading to greenish on standing or heating to 150°. In presence of oxide of iron, cryptopine is said to dissolve in sulphuric acid with deep violet-rose colour, changing to violet and deep blue, and becoming greenish on heating to 150°. The hydrochloride gives a yellow coloration when first treated with acid. 2 According to Merck, laudanine gives a violet colour with ferric chloride. COLOUR-REACTIONS OF OPIUM BASES. 305 Hesse employs the colour-reactions of the opium bases -with pure sulphuric acid as a means of grouping them, thus : — Coloration at 150'. Alkaloids. Dirty dark green. Dirty red-violet. Dirty green to green-brown. Dark violet or blue. Black-brown to dark brown. Codeine, morphine, pseudomorphine. Codamine, laudanine, laudanosine, narcotine, hydrocotamine. Tliebaine, cryptopine, protopine. Papaverine.! Narceine, lanthopine. With acid containing iron, codamine,* laudanine and laudanosine are stated to give a dark violet colour, while narcotine and hydro- cotamine react in the same way as with pure acid. It will be seen that several of the reactions described by Hesse differ in a marked manner from those recorded by other observers. As in the case of other colour-observations, the only safe way is to compare the substance under examination side by side with pro- ducts of known purity. Lafon's reagent, prepared by dissolving 1 gramme of ammonium selenite in 20 c.c. of strong sulphuric acid, is stated by da Sil va (Compt. Rend., cxii. 1266) to give the following colour- reactions with the opium bases : — Codeine, magnificent green coloration ; morphine, greenish blue, changing to chestnut brown ; narcotine, blue, turning violet and then reddish, with slight reddish precipitate after long standing ; nurceine, yellowish green, changed to brown and red, with red precipitate on standing ; papaveriney blue, passing to dull green, violet and red, with a slight bluish precipitate on standing. Determination and Separation of Opium Bases. Morphine, codeine, and thebaine may be titrated with ease and accuracy by a standard mineral acid, using litmus or methyl- orange as an indicator (page 130). On the contrary, they have little or no action on phenolphthalein, the reaction with which, however, is not sharp in the case of morphine (page 311). Papaverine, narcotine and narceine, on the contrary, do not affect Htmus, and their salts may be titrated with litmus and stan- ^ Hesse states that, when absolutely pure, papaverine dissolves in small quantities of sulphuric acid without coloration ; but, generally, on warming a crystal of papaverine with concentrated sulphuric acid, a dark blue colour is produced. Dott also obtains no coloration in the cold, and the blue coloiir on strongly heating only. A red coloration before heating is generally due io thebaine. VOL. III. PART II. Cr 306 SEPARATION OF OPIUM BASES. dard alkali, just as if the acid were uncombined ( P 1 u g g e, Pharm. Jour., [3], xx. 401); and the first two of them being alkaloids also evince their feeble basic characters by the fact that they are extracted by chloroform from acid solutions. Their salts, especially with certain organic acids (e.g., acetic, benzoic), are very unstable, many of them being decomposed slowly by cold and rapidly by hot water. Hence, when a compound of the alkaloid with a mineral acid is treated with a neutral solution of acetate of sodium, or even with a sHghtly acid solution, the free alkaloid is precipitated.^ A faintly acid solution of sodium acetate will indicate 1 part in 40,000 of narcotine, 1 in 30,000 of papaverine, and 1 in 600 of narceine, none of the other opium bases being precipitated. On the foregoing and similar facts, P. C. Plugge {Analyst, xii. 197) has based the following process of separating the leading alkaloids of opium. The aqueous solution of the hydrochlorides is mixed with a concentrated solution of sodium acetate, and filtered after twenty-four hours. The precipitate, con- sisting of pure narcotine and papaverine, is washed with a little water, and dissolved in a minimum of dilute hydrochloric acid. The liquid is diluted till it contains not more than ;jJq of nar- cotine, when potassium ferricyanide is added. This precipitates papaverine very perfectly. After standing twenty-four hours the liquid is filtered, and the precipitate of papaverine hydrof erri- cyanide either weighed as such, or washed with a little water, decomposed by dilute caustic soda, and the liberated alkaloid dis- solved in dilute acid and reprecipitated with ammonia. In the filtrate from the precipitate produced by the ferricyanide the nar- cotine is precipitated by ammonia. The filtrate from the precipi- tate produced by sodium acetate is concentrated to a small volume at 100°, cooled thoroughly, and filtered after twenty-four hours. The deposited narceine is filtered off, and washed with a little water. The filtrate is mixed with a strong solution of sodium salicylate, and the crystalline precipitate of thebaine salicylate separated after twenty-four hours, and washed with a little water, dried at 100°, and weighed. On subsequent treatment on the filter with dilute soda or ammonia, till the washings are free from salicylic acid (as indicated by evaporating to dryness, and the non- production of a violet coloration on moistening the residue with ^ This observation is due to P. C. Plugge {Arch. Pharm., [3], xxiv. 994; Analyst, xii. 197). The reaction not only distinguishes papaverine, narcotine and narceine from morphine, codeine, and thebaine, but also from caflfeine, cocaine, conine, atropine, pilocarpine, strychnine, brucine, quinine, cincho- nine and cinchonidine. The cinchona bases are precipitated if the sodium acetate is at all alkaline. SEPARATION OF OPIUM BASES. 307 ferric chloride), pure thebaine is left. The filtrate from the thebaine salicylate is acidulated with hydrochloric acid, the precipitated salicylic acid filtered ofi", and the filtrate repeatedly shaken with chloroform. This dissolves the remaining sahcylic acid, and traces of narceine and thebaine, which may be recovered by evaporating the cliloroform. The acid hquid separated therefrom is concen- trated somewhat, made exactly neutral to litmus, and mixed with potassium thiocyanate (sulphocyanide), which throws down the codeine as an acid thiocyanate. Twenty-four hours should be allowed for its complete separation.^ The filtrate should be treated with a sUght excess of ammonia, and time allowed for the separ- ated morphine to become crystalline. The Hquid is then shaken with chloroform or ether to remove the remainder of the codeine and traces of other bases. After separation it is acidulated to dis- solve the morphine, heated to 60° C, and the morphine shaken out with hot amylic alcohol, after addition of a slight excess of ammonia or carbonate of sodium. Plugge's results, obtained in test experiments, except in the separation of codeine and morphine, were very satisfactory, considering the difficult nature of the problem to be solved. 1 But the methods are not to be regarded as having the same quantitative accuracy as those for the separation of the metals. Another method of separating the principal alkaloids of opium consists in treating the solution with an alkaline carbonate or am- monia, and agitating with benzene, when morphine and narceine are left insoluble, the remainder passing into the benzene. Much the same separation occurs with chloroform, except that pseudo- morphine is left with the insoluble alkaloids. D. B. Dott has communicated to the author the following method of separating the chief bases of opium : — Treat the solution of their mixed hydrochlorides with a 10 per cent, solution of caustic soda, and wash the precipitate, which will consist of narcotine, papaverine and thebaine, the alkaline solution containing morphine, codeine and narceine. On agitating the filtrate with chloroform, the codeine will be extracted; and on separating the alkaline Hquid, acidulating it, and rendering it faintly alkaline with ammonia, the morphine wiU be precipitated, the narceine, from its greater solubility, remaining dissolved. It can be recovered by * The separation of codeine and morphine by this process is very imperfect. If the solution be too strong, morphine is precipitated with the codeine, and if this condition be avoided the precipitation of the codeine is incomplete. In test-experiments Plugge only recovered 70 per cent, of the codeine used. Hence it is better to omit the precipitation with thiocyanate altogether, pre- cipitate the morphine with ammonia, and extract the codeine from the filtrate by ether or chloroform, after adding caustic soda (compare page 323). 308 SEPARATION OF OPIUM BASES. evaporating the liquid to dryness and treating the residue with strong alcohol. From the bases precipitated by caustic soda, the thebaine can be separated fairly well by crystallisation as acid tartrate. Narcotine and papaverine may also be separated from thebaine (and codeine) by dissolving the free bases in dilute alcohol, rendering the liquid faintly acid with acetic acid, and adding three volumes of boiling water, when the narcotine and papaverine are precipitated ; or sodium acetate may be used as already described. Narcotine and papaverine may likewise be separated by solution in boiling water containing one-third part of oxalic acid, when an acid papaverine oxalate crystallises out on cooling. The process should be repeated several times, and the narcotine finally precipitated by ammonia and crystaUised from boiling alcohol. The following is an epitome of Hesse's method of separating the rarer opium bases from the mother-liquors left from the prepara- tion of morphine by the Eobertson-Gregory process.^ The aqueous extract of opium is first precipitated by calcium chloride, the filtrate from the calcium meconate concentrated, and the hydrochlorides of morphine, pseudomorphine and codeine sepa- rated by crystallisation. The mother-liquor is diluted with an equal bulk of boiling water, excess of ammonia added, the precipitate removed by filtration and dissolved in acetic acid. The filtrate is agitated with ether, the ethereal layer shaken with excess of acetic acid, and the acetic solution mixed with that of the ammonia precipitate. The acetic acid solution is then treated with excess of caustic soda, which precipitates papaverine, narcotine, thebaine, some cryptopine, protopine, laudanosine and hydrocotarnine ; while lanthopine, laudanine, codamine, meconidine, and a portion of the cryptopine remain in solution. The alkaline liquid is neutralised, ammonia added, the bases again extracted by ether, and shaken out with acetic acid. The acetic acid is neutralised with ammonia, when a little lanthopine separates out in twenty- four hours, and the filtrate is treated with more ammonia. The precipitate formed is dissolved in a very small quantity of boiling dilute alcohol, which on cooling deposits white crystals of mixed laudanine and cryptopine. On evaporating the alcoholic solution,^ and treatment of rhe residue with ether, a solution is obtained from which codamine may be isolated, either by addition of fused * For E. Kauder'a modification of Hesse's method, see Arch. Pharm., ocxxviii. 419 ; and Jour. Ghem, Soc.j Ix. 227, 2 Hesse could obtain no meconidine from this solution, and hence concludes that it had been decomposed by the preceding operations, as he had pre- viously obtained it from a similar source by another process {Ann. Ghem. Pharm., cliii. 47 ; Watts' Diet. Ghem., vi. 883). SEPARATION OF OPIUM BASES. 309 calcium chloride (which causes water, colouring-matter, and crystals of codamine to separate), or by conversion into the acetate, and this into the hydriodide. The mixture of bases insoluble in caustic soda is digested with dilute alcohol, and acetic acid added till the liquid is faintly acid to litmus. On adding three measures of boiling water, a crystalline precipitate of papaverine and narcotine is thrown down. The filtrate, freed from alcohol by evaporation, on adding strong hydro- chloric acid, will give a precipitate of cryptopine hydrochloride ; but in order to avoid the conversion of thebaine into its non-crystalline isomer thebaicine, it is preferable to add tartaric acid, which throws down crystalline tliehaine acid tartrate. The mother-liquor of this is neutralised with ammonia, and mixed with 3 per cent, of its weight of sodium bicarbonate made into a paste with water. After standing about a week, a black, pitchy mass separates, the filtrate from which gives with ammonia a precipitate which is treated with boiling benzene, the filtrate being also extracted by agitation with benzene. On shaking the united benzene solution with a saturated aqueous solution of sodium bicarbonate, laudano- sine crystallises out; and the benzene filtered from this yields hydrocotarnine hydrochloride on passing hydrochloric acid gas. The portion of the ammonia precipitate left undissolved by benzene contains cryptopine and protopine. These bases are converted in nydrochlorides, and the solution treated with strong hydrochloric acid, when the protopine hydrochloride forms a horny deposit which adheres to the sides of the glass, and is easily freed from the gelatinous cryptopine salt by washing with a little water. Narceine is mentioned as existing in the liquors, but the stage at which it is separated is not stated. Morphine. Morphia. CiyHigNOg; Ci7Hi7NO(OH)2 ; or Ci7Hi/0H)N0.0H. Morphine is the most important of the bases contained in opium, in which it exists in combination with sulphuric and meconic acids. The mode of preparing morphine may be gathered from the methods of assaying opium (see also last page). Morphine crystallises in transparent, colourless, trimetric prisms, which are usually very short. They contain one molecule of water, ^ which is given off slowly at a temperature of 90° and more rapidly at 100° C. {Pharm. Jour., [3], xviii. 701, 801 ; xix. 61, 148, 180). At or above 200° morphine partially volatilises, melts, and turns brown, becoming carbonised at a somewhat higher temperature. ^ D. B, Dott found the proportion of water lost to correspond more nearly toSCyHigNOg + QHsO. 310 SOLUBILITIES OF MORPHINE. Morphine is inodorous, has a persistent bitter taste, and is a powerful narcotic poison. Morphine is nearly insoluble in cold water, requiring, according to Chastaing, 33,333 parts at 3° and 4545 at 22V At 42°, the solubility is 1 in 2380, and in boiling water about 1 in 460 {Year- Booh Pharm., 1882, p. 30). The solution has an alkaline reaction. Morphine dissolves in 30 parts of boiling or 50 of cold absolute alcohol, and in a somewhat smaller quantity of rectified spirit.' In ether and chloroform it is almost insoluble when in a crystallised state, but dissolves sparingly when freshly-precipitated and amorphous. A useful solvent for morphia is a mixture of equal volumes of ether and acetic ether (ethyl acetate) ; but even in this its solubility is limited, especially in the crystalline state. Amylic alcohol dissolves morphine sparingly (1 : 150) in the cold, but when heated is a fairly good solvent for it (1 : 50). The alkaloid dissolves best when liberated from one of its salts in presence of amylic alcohol. In benzene and petroleum spirit, morphine is practically insoluble, as also in volatile oils. According to Florio {Gaz. Cliim. Italiano^ xiii. 496) 100 parts of the following solvents dissolve of morphine : — Solvent. Morphine dissolved by 100 of Solvent. At 10°-11° C. At 56" C. At 78° C. Alcohol, absolute, .... „ 90 per cent., , „ 75 per cent., Wood -spirit, Fusel-oil, Benzene Chloroform Ether, absolute, .... 1-132 0-377 0-223 1-675 0-268 0-020 0040 0-023 8-466 3-235 8-623 2-991 1-985 2-247 A. B. Prescott {Jour. Chem. Soc, xxix. 405) has pointed out the great influence the physical condition of morphine has upon its relation to solvents, and has determined the proportion of different solvents requisite for the solution of morphine in the crystalline, amorphous, and " nascent " conditions ; by the last term meaning that in which the alkaloid exists when liberated by ammonia or an alkaline carbonate from the aqueous solution of one of its salts. The following are Prescott's figures : — Dott gives the solubility of morphine in water at 15° C. as 1 in 2500. PROPERTIES OF MORPHINE. 311 Condition of the Morphine. Parts of Solvent required. Ether. Chloroform. 1 Crystallised, . Amorphous powder, . "Nascent "state, . 6148 2112 1062 4379 1977 861 91 91 8930 1997 Other figures for the solubility of morphine are given on page 301. Solutions of caustic potash and soda dissolve morphia readily, as also do baryta and lime water, and, to a limited extent, am- monia also. Solutions of caustic alkalies dissolve quantities of morphine equivalent to the bases contained in them, with the formation of unstable morphinates which are decomposed by carbonic acid and assume a dark brown colour on exposure to air. Crystalline morphinates of potassium, barium, and calcium have been obtained. From these facts, and the blue reaction with ferric chloride, Chastaing (Jour. Pharm., [5], iv. 19) inferred that morphine possessed a phenoloid character, and this view has been fully borne out by the later researches of Grimaux and Hesse (page 296). Solutions of morphine are IsBvo-rotatory. In alcoholic or dilute acid solution, S^ is said to be — 89°'8 and 8^—70°. For the hydrochloride, the value is S„= - 100°-67 -T'U C. In alka- line solution, the value of Sr for morphine is stated to be —45° "2. Morphine is very sensitive to the action of oxidising agents, a fact which is often used for its detection (page 314 et seq.). It reduces salts of gold and silver, permanganates, ferricyanides, iodic and periodic acids, &c. The reactions of morphine with strong sulphuric and nitric acids are described on pages 313, 314. When morphine is heated with strong hydrochloric acid or zinc chloride it loses the elements of water and is converted into apomorphine, C^yHj^NOg (page 3 1 9). Salts of Morphine. Morphine dissolves readily in dilute acids, forming salts which are perfectly neutral in reaction to litmus and methyl-orange, and hence it may be titrated with accuracy by the aid of standard hydrochloric acid and either of these indicators. With phenol- phthalein morphine does not give a sharp reaction, but the point of neutrality is approximately the same as if the acid of the morphine salt were in a free state. The salts of morphine are mostly crystallisable, and are all bitter and very poisonous. They are generally soluble in water and in 312 SALTS OF MORPHINE. alcohol, but are insoluble or only slightly soluble in amylic alcohol, ether, chloroform, benzene, or petroleum spirit. Morphine is not removed from its acid or neutral solutions by agitation with any of the above solvents, except imperfectly by amylic alcohol. The following table shows the formulae of the more important salts of morphine, the percentage of morphine hydrate, the relative dose, and D. B. Dott's figures for their solubility in cold water (Pharm. Jour., [3], xiii. 404 ; xvi. 653) : — Morphine Salt. Formula. Morphine Hydrate, per cent. Relative Dose. SolubUity in Water at 15°-5 C. Hydrochloride, BHCl + 3H2O 80-69 1-00 1 part in 24. Sulphate, B2,H2S04 + 5H2O 79-94 1-00 „ 23. Acetate, . . B,C2H402 + 3H2O 75-93 104 2i. Lactate, . B.CsHeOg 80-80 1-00 8. Tartrate, B2,C4H606 + 3H2O 78-29 1-02 9f. Meconate, B2,C7H407 + 5H2O 70-46 1-14 „ 34. illf(9r^Mwe-H2/^^^^^^<^^*'^^> or Morphia Hydrochlorate, BHCl + 3H2O, crystallises in colourless silky fibres, soluble in half its weight of boiling water and in 40 parts of cold rectified spirit. It becomes anhydrous at 100° C. The commercial salt often has a buff 01 brownish tint from admixture of resinous matters, which are detected by the brown or black colour assumed by the salt when heated to 130° C. Morphine Hydriodide, BHI + SHgO, is obtained as a compact mass of hair-like needles on mixing a concentrated alcoholic solu- tion of potassium iodide with a concentrated solution of morphine hydrochloride. The product only slowly redissolves on adding more spirit, and is very sparingly soluble in water, especially in presence of potassium iodide. The hydrobromide can be obtained similarly. Morphine Sulphate, B2H2SO4 + 5H2O, closely resembles the hydrochloride. It loses 3H2O at 100°, and the remaining two atoms at 110°. It exists naturally in opium. Morphine Acetate (see above) is a white, or faintly yellowish white, obscurely crystalline powder. It is readily soluble and crystallisable. It is partially decomposed by boiling or evaporating its aqueous solution, crystals of morphine being deposited. Morphine Tartrate, BgC^HgOg -h SHgO, is readily soluble, but the acid tartrate, BC^HgOg, only sparingly so. Their solutions are not precipitated by caustic alkalies, alkaline carbonates, or chloride REACTIONS OF MORPHINE. 313 of calcium. The tartrate is best detected by precipitating the con- centrated solution with potassium acetate and acetic acid in presence of alcohol (Yol. I. page 457). After boiling off the alcohol, the morphia can be precipitated from the filtrate by an alkaline carbonate or ammonia. Morphine Meconate (see above) is interesting as being the form in which morphia largely exists in opium. When morphine and meconic acid are dissolved in absolute alcohol, and the solution is evaporated, an amorphous, hygroscopic, very soluble residue is obtained, which in concentrated sohition deposits crystals of neutral morphine meconate containing 5 aqua, even in presence of suffi- cient meconic acid to form the acid salt. Detection and Determination of Morphine. Free morphine, when pure or in the form of one of its ordinary salts, is readily detected. Its determination is easy when un- mixed with interfering substances, but as it exists in opium is attended with considerable difficulties. Most of the colour-reactions of morphia are best observed by operating on the solid substance, but for certain qualitative tests and for ail quantitative methods the alkaloid must be in solution. A. Reactions of Solid Morphine, For observing these reactions a minute fragment or crystal of the solid alkaloid or its salt should be employed, and the experiment should be conducted in a small porcelain basin or crucible. The residue obtained by the evapora- tion of the solution of morphine in alcohol or amylic alcohol is well-suited for the operation. 1. Solid morphine treated with a drop of a perfectly neutral solu- tion of ferric chloride or iron-alum gives a very characteristic deep greenish blue colour, changed to green by excess of the re- agent. The colouring matter is not taken up by chloroform. The colour is destroyed by free acid, by heat, or by contact with alcohol.^ Pseudomorphine also gives a blue colour with ferric chloride, and codamine a dark green. 2. Nitric acid (1"42 sp. gr.) added to solid morphia turns it an orange-red colour, which is changed to yellow on heating, and destroyed on adding sodium thiosulphate (hyposulphite). The * The coloration is produced in strong solutions of morphine, but becomes imperceptible with moderate dilution. J. L. Armitage {Pharm. Jour. , [3], xviii. 761) has pointed out that even in solutions far too dilute to give the reaction, the morphine may be detected by adding potassium ferricyanide, which produces a blue or green coloration. Armitage attributes this reaction to the reduction of the iron to the ferrous state, and the reaction of this with the ferricyanide to form Turnbull's blue ; but it is more probable that the ferricyanide is reduced to ferrocyanide, and then reacts with the ferric salt to form Prussian blue (compare page 31 7). 314 COLOUR-REACTIONS OF MORPHINE. coloration is said to he due to the formation of a body of the formula CjoHgNOg, which yields picric acid when heated with water to 100°. 3. Solid morphine, when pure, is commonly said to yield no coloration in the cold on adding pure concentrated sulphuric acid ; but according to Dott {Pharm. Jour., [3], xii. 615) a distinct, though faint, pink colour is produced. On heating to 150°, a dirty green (or rose-red) colour is developed, and on raising the temperature still further the solution becomes almost black. On allowing it to cool and diluting with water, a greenish blue colour is produced, wliich on addition of ammonia in excess becomes green. 4. On adding oxidising agents to the solution of solid morphine in cold concentrated sulphuric acid, the following reactions are pro- duced.-^ a. After adding a drop or two of water to heat the mix- ture, the subsequent addition of nitric acid will produce a rose-red coloration, changing to brown. The reaction is very delicate. h. Potassium chlorate gives reactions similar to those with nitric acid. If the alkaloid be first heated with concentrated sulphuric to 100° for half an hour, and a crystal of potassium chlorate or nitrate added to the previously cooled violet-red solution, a beau- tiful violet-blue colour is produced, which passes into a dark blood- red, changing to yellow, c. If the sulphuric acid solution be heated on the water-bath to 100°, and a minute fragment of pure potassium perchlorate^ be added, a deep brown or reddish brown coloration is produced, which rapidly spreads through the liquid. The colour is destroyed on dilution. L. S i e b o 1 d, to whom the test is due, did not observe a similar reaction with any other alkaloid, d. Potas- sium bichromate is reduced with production of green colour. (No colour-reaction is produced if for the bichromate be substituted the dioxide of lead or manganese. Distinction from strychnine.) e. On adding sodium or potassium arseniate, and warming gently, a slate- blue colour is produced, which on raising the temperature passes into green, then into deep blue, and finally, when the acid begins to volatilise, again into dark olive-green. On diluting moderately with water, a reddish brown coloration is produced, changing to dirty bluish and green on further dilution ; and on agitating with chloro- form the latter liquid is coloured violet-blue (D o n a t h). If 1 The reactions in question have been verifieci in the author's laboratory byW. H. Barraclough, and the description given in the text is in accord- ance with his results. ^ The perchlorate must be free from chlorate, which is ensured by heating it with hydrochloric acid as long as chlorine is evolved. The salt is then washed with cold water and dried. COLOUR-REACTIONS OF MORPHINE. 315 sodium phosphate be substituted for the arseniate^ and heat applied till acid fumes appear, the mixture becomes violet, chang- ing to brown or olive-green. If, after cooling, water be gradually- added, a reddish brown coloration appears, changing to dirty bluish green on further dilution. On now shaking with chloroform, the latter liquid acquires a fine blue colour. /. Sodium or ammonium molybdate added to the sulphuric acid solution gives a fine violet coloration, changing to blue and dirty green, and finally almost vanishing. The reaction of morphine with sulphomolybdic acid may be observed with more certainty by adding previously pre- pared Frohde's reagent (page 147) to the solid morphine. Papa- verine and a few glucosides give a similar reaction. 5. If solid morphine be mixed with from 2 to 8 parts of powdered cane-sugar, or solutions of the two bodies be mixed and evaporated to dryness, addition of a drop of concentrated sulphuric acid wiU produce a beautiful purple colour, changing gradually to blood-red and brownish red, becoming olive-brown on dilution with water. The colouring matter is not soluble in chloroform. The test may be applied to a solution of morphine by saturating the liquid with sugar, and pouring it carefully on to some concentrated sulphuric acid, when a purple or rose-red coloration will be ob- served at the junction of the two fluids. Codeine gives a very similar reaction (Schneider). According to H. W e p p e n the delicacy of this test is much increased by adding a drop of bromine- water after the sulphuric acid, this modification rendering the reaction equal if not superior to reactions 3 and 4 c, and less dependent on the purity of the morphia. M. Robin mixes the alkaloid with twice its weight of powdered sugar, and adds one or two drops of pure sulphuric acid, and states that morphine hydrochloride gives a beautiful rose colour, changing first to the tint of a solution of potassium permanganate, and then to violet and dark green, while codeine gives a cherry-red colour changing to violet, and narcotine a beautiful and very persistent mahogany-brown colour.^ B. Reactions of Morphine in solution. The following reactions 1 For convenience, this test is described here, but it seems improbable that the reaction is due to oxidation. 2 Atropine gives with sugar and sulphuric acid a violet coloration, changing to brown ; veratrine, a deep green ; santonin, a red colour, changing to cofFee- black. Salicin gives a vivid red. Pure aconitine gives no reaction, but mixed aconite alkaloids as extracted from the root give a fine cherry-red coloration, changing to crimson. No reaction is given by strychnine, brucine, cocaine, pilocarpine, caffeine, beberine, apomorphine, cupreine, or the cin- chona bases (J. F. Burnett). 316 DETERMINATION OF MORPHINE. are yielded by an aqueous solution of the hydrochloride or acetate of morphine : — 1. On adding to a tolerably concentrated solution of a salt of morphine a fixed caustic alkah, an alkaline carbonate, ammonia, or lime-water, hydrated morphine, Cj^H^gNOg + HgO, is thrown down as a white precipitate speedily becoming crystalline. The precipitate is almost insoluble in perfectly cold water, but dissolves in excess of ammonia or lime-water, and very readily in excess of caustic alkali. The alkaline carbonates, used in excess, redissolve the precipitate somewhat, but it is insoluble in excess of bicarbonates. Excess of magnesia precipitates the alkaloid com- pletely. The morphia precipitated by the foregoing reagents, and allowed time to become crystalline, presents a characteristic appear- ance under the microscope. A fairly accurate determination of morphine may be made in the absence of interfering substances, by precipitating the tolerably concentrated, cold, aqueous solution with sodium bicarbonate, allow- ing time for the precipitate to become crystalline, filtering, washing moderately with very cold water (preferably saturated with mor- phine), drying at 100° or 120°, and weighing the anhydrous morphine, C^^H-^gNOg, when the weight becomes constant. Instead of drying and weighing the alkaloid, the washed preci- pitate may be placed, together with the filter, in a moderate excess of standard acid, and the excess employed ascertained by titration with litmus or methyl-orange (not phenolphthalein). 1 c.c. of decinormal acid neutralises 0'0285 gramme of anhydrous morphine. 2. If morphia be liberated from the solution of a salt by one of the reagents mentioned above, and the liquid and suspended pre- cipitate be at once shaken with hot amylic alcohol, cold acetic ether, or a mixture of equal measures of ether and acetic ether,^ the morphia passes into solution, though with some difiiculty, and may be obtained in a free state by separating the ethereal liquid, and evaporating it to dryness at a gentle heat. If the liberated morphia be allowed to crystallise before subjecting it to agitation with the solvent, its solution becomes very difficult to effect. For quantitative purposes, hot amylic alcohol should be employed as the solvent. It should be added before the alkaloid is liberated, which should be done by ammonia, magnesia or sodium bicarbonate, and the agitation should be conducted immediately, and the separa- tion and re-agitation effected without delay. On evaporation of the amylic alcohol at 100° the anhydrous morphine will remain as ^ The acetic ether must be free from acid. This may be ensured by agitating it with some sodium bicarbonate before use. REACTIONS OF MORPHINE. 317 a residue, which can be weighed,^ or the amylic alcohol containing the alkaloid in solution may be titrated by dilute standard acid and methyl-orange, as described on page 131. If desired, the alkaloid may be recovered from its amylic alcohol solution by repeated agitation with dilute hydrochloric acid,^ and then repre- cipitated from the aqueous liquid by ammonia, or an alkaline bicarbonate. This affords a valuable means of purifying morphine and separating it from other alkaloids. To effect complete extraction of the morphine liberated by magnesia, ammonia, or an alkaline bicarbonate, several agitations with amylic alcohol are necessary. If ammonia be employed, sufficient passes into the amylic alcohol bo vitiate the subsequent determination of the morphine by titration ; while if the amylic alcohol be freed from ammonia by agitation with water, or even with brine, a portion of the morphine is dissolved out. If the separated amylic alcohol be distilled off, the residual morphine may be titrated, or the difficulty avoided by using magnesia instead of ammonia. 3. A volumetric determination of morphine may be made by means of Mayer's solution, as described on page 140. The method has little practical utility. Further information on the determination of morphine will be found in the section on the assay of opium. 4. Morphine readily reduces ferricyanides to ferrocyanides, with formation of pseudomorphine (oxydimorphine) : — 4C17H19NO3, HCl + 4K3FeCye = 2(C34H3,,N206, 2 HCl) + 3K4FeCy6 + H4FeCye . Consequently, on adding to the solution of a salt of morphine, slightly acidulated with hydrochloric acid, a mixture of aqueous solutions of ferric chloride and potassium ferricyanide, a blue coloration or precipitate of Prussian blue is produced. This reaction may be conveniently employed for detecting morphine in presence of the cinchona bases. L. Kieffer {Annal. Ohem. Pharm., ciii. 274) has proposed to utilise the reaction with ferricyanide for the quantitative deter- mination of morphine. For this purpose he adds a known weight of solid potassium ferricyanide to the morphine or its salt, and mixes them in a mortar with a minimum quantity of water. The contents of the mortar are rinsed into a flask, potassium iodide and hydrochloric acid added, and the liberated iodine determined ^ There is some evidence that morphine forms a compound with amylic alcohol not decomposed by evaporation at the ordinary temperature {Pharm, Jour., [3], xviiL 161). '^ A solution of morphine in hydrochloric acid cannot be shaken with amylic alcohol without extraccion of some of the alkaloid, probably in the form of hydrochloride. 318 IODIC ACID TEST FOR MORPHINE. by decinormal sodium thiosulphate (hyposulphite). The difference between the volume required and that used in a blank experiment with the same weight of potassium ferricyanide corresponds to the salt reduced by the morphine. One c.c. of difference in the f^ thiosulphate used represents '0292 of anhydrous morphine.^ Venturini (Gaz. Chim. ItaL^ xvi. 239) reports favourably of Kieffer's process. The author's results were discouraging. 6. On mixing a solution of morphine with one of iodine dis- solved in hydriodic acid, a crystalline precipitate is formed even in extremely dilute solutions. Under the microscope the crystalline form is characteristic of morphine, which may thus be distinguished from papaverine and codeine, which bases also give crystalline pre- cipitates with the reagent, while narcotine, narceine and thebaine yield amorphous precipitates. 6. Addition of chlorine or bromine water, followed by ammonia, occasions in moderately concentrated solutions of morphine a brown colour or red coloration gradually changing to brown. 7. Morphine and its salts reduce iodic acid with liberation of iodine. This reaction is also produced by albuminoid and various other organic bodies, so that it is not absolute proof of the presence of morphia. The test becomes much improved and increased in delicacy by the following mode of operating : — To the solution to be tested for morphia, as nearly neutral as possible, is added one of iodic acid in 15 parts of water. In presence of 1 part of morphia in 20,000 of liquid a yellow colora- tion is observed. In moderately strong solutions of morphine addition of starch-liquor gradually changes the yellow colour to blue, but not in solutions containing less than 1 per 1000. This is important, as with other reducing agents the blue colour is well marked in far more dilute liquids. On adding excess of ammonia to the yellow liquid the colour is discharged if due to foreign matter, but distinctly deepened if due to morphia. If a solution of morphine, which is too dilute to give a blue colour with iodic acid and starch, be mixed with these reagents, and some highly dilute ammonia allowed to flow from a pipette on to the surface of the liquid, two coloured rings make their appearance at the junction of the fluids. A blue ring is seen in the lower acid layer and a brown one in the upper alkaline portion. If a dilute solution of morphia be mixed with one of starch, and evaporated to dryness in a por- celain crucible at a gentle heat, and the residue, after cooHng, be * It is possible that Kieffer's process might be applied to the amylic alcohol solution of morphine, by agitating it with potassium ferricyanide solution. In such a case, ammonia, if present, would not interfere. APOMORPHINE. 319 moistened with iodic acid, a blue colour will be produced in pre- sence of 1-20,000 of a grain of morphia (A. Dupr^). Another way of employing the test is to agitate a solution of iodic acid with an equal measure of carbon disulphide, which should not become coloured even after adding a drop or two of dilute sulphuric acid and again shaking, If the solution to be tested for morphine be now added to the mixture, and the whole again shaken, the carbon disulphide will be found after separation to have a violet colour from dissolved iodine if morphine be present, and the depth of tint will afford an indication of the amount. Morphine can be recognised in this way in a single drop of paragoric or tincture of opium. Stein and others have described a colorimetric method of estimating morphine, based in the iodic acid reaction. In employing the iodic acid test it is essential that the reagent should not give free iodine on treatment with a drop of dilute sulphuric or acetic acid. 8. Solutions of morphine salts give no crystalline precipitate with either potassium chromate, thiocyanate (sulphocyanide) or ferro- cyanide (distinction from strychnine). Apomokphine, CiyHiyNOg. When morphine or its hydro- chloride is heated to 140°-150° C. in a sealed tube, with a large excess of strong hydrochloric acid, or with zinc chloride at 110°, it is converted into the hydrochloride of apomorphine, the formula of which base differs from that of the parent alkaloid by the elements of water, though its formation is probably attended by polymerisation. Apomorphine may be obtained in a state of purity by dissolving the contents of the tube in water, adding excess of acid carbonate of sodium, and agitating with ether or chloroform, in either of which apomorphine is freely soluble (difference from morphine). The ethereal solution is separated and shaken with a very little strong hydrochloric acid, when crystals of the hydrochloride of apomorphine are deposited. These are separated, washed with a little cold water, and purified by recrystallisation. From its aqueous solution of the hydrochloride, sodium bicarbonate precipitates free apomorphine as a snow-white amorphous substance, readily soluble in alcohol, ether, chloroform and benzene, which speedily turns green on exposure to the air. The changed alkaloid is partially soluble in water and alcohol with emerald-green colour, in ether with magnificent rose-purple, and in chloroform with fine violet tint. The colourless solutions of the unchanged substance soon acquire these tints. In its physio- logical effects, apomorphine differs from morphine in a very marked manner, being a prompt and non-irritant emetic. From 0*001 320 APOMORPHINE. to 0*010 is the adult medicinal dose by the stomach. Dangerous and even fatal symptoms have followed the hypodermic injection of 0*012 gramme. Apomorphine gives a crimson-red colour with nitric acid, and brown with iodic acid, but (unlike morphine) yields a rose-red or amethystine colour with ferric chloride, changing to violet and black. The most delicate reaction of apomorphine is the production of a green coloration when the solution is ren- dered faintly alkaline with potassium hydrogen carbonate and exposed to the air. With a solution containing 1 part in 100,000, the green colour appears within ten minutes. Apomorphine is said to be liable to be formed in old solutions of morphine hydrochloride, which consequently acquire emetic properties; but the statement is disputed by Dott, and requires confirmation (Pharm. Jour., [3], xvi. 287, 299, 604 ; xvii. 80). Apomorphine Hydrochloride, C-^^jH.^>jN02^Cl, forms anhydrous, minute, shining crystals, which turn greenish on exposure to light and air. It is freely soluble in water and alcohol, forming a neutral solution, which turns green on boiling or standing, and keeps better if very faintly acid. The freshly-made aqueous solution should be colourless, or nearly so. It is generally held that if a 1 per cent, solution be emerald-green, the sample should be rejected for medical use; but D. B. Dott (Pharm. Jour., [3], xxi. 916) has pointed out that the coloration is so intense that very little actual change is thereby indicated. Morrell found an old solution which had been exposed to light for three months to act quite effectively.^ Basic Associates of Morphine. As already stated, opium contains a large number of bases, some of which are present in very minute amount, or are altogether absent from some samples. The names, formulae, solubilities, and chief colour-reactions of these alkaloids have already been given (page 294 to 305), and morphine has been described at length (page 309). The following are additional facts respecting the less important bases of opium. CoDAMiNE, CgongsNO^, melts at 126° when crystallised from benzene, and 121° when separated from alcohol or ether. It forms large six-sided prisms, which can be sublimed. It dissolves moder- ately easily in hot water, giving an alkaline solution. Its salts, which are amorphous, give precipitates with caustic alkalies and ^Morrell finds that a patient who is made violently ill by } grain of apomorphine hydrochloride administered hypodermically, can take | grain thrice daily in the form of pills. Apomorphine acts as a powerful expectorant in cases of chronic bronchitis. CODEINE. 321 ammonia, soluble in excess of either reagent with nitric acid; codamine gives a dark green coloration with sulphuric acid, and in presence of a minute quantity of ferric chloride a greenish blue. For other colour-reactions and solubilities, see page 301 e^ seq. Codeine. Codeia. CigHgiNOg, or Ci^Hi^NOCOH^OCHg. This base has the constitution of a morphine methyl-ester. The relation of codeine to morphine and synthesis therefrom are described on page 167. Its theoretical relations and constitution have been recently further investigated by K n o r r (Ber., xxii. 181, 1113) and Skraup and Wiegmann {Monatsch, x. 732). Codeine occurs in opium in proportions ranging from 0*1 to 1"0 per cent.-^ Codeine crystallises from dry ether or carbon disulphide in smaU anhydrous prisms. From water it is deposited in weU-defined octohedra or orthorhombic prisms containing 1 aqua and melting under boihng water to an oily liquid. Anhydrous codeine melts at 150°-155°, and solidifies to a crystalhne mass on cooling. Codeine is somewhat soluble in water, requiring 75 to 80 parts of cold water, or 17 at the boiling-point. It is readily soluble in alcohol, ether, amylic alcohol, chloroform and benzene, but is almost insoluble in petroleum spirit (compare page 301). Codeine is as soluble in ammonia as in water, a fact utilised to separate it from morphine, but it is practically insoluble in excess of caustic potash or soda, and is precipitated by these reagents from its aqueous solution, if not too dilute.^ Solutions of codeine are optically active, the rotatory power being much affected by the nature of the solvent, and the presence and proportion of free acid. In alcoholic solution Sj = -136°; in chloroform, -112°. Codeine has a bitter taste, and resembles morphine in its physio- logical action. It is official in the British and several foreign Pharmacopoeias, and is chiefly employed to aUay restlessness, cough, and other symptoms for which opium is generally prescribed, and when the latter medicine is not tolerated. In phthisis, it appears to prevent and appease the tickling irritation of the cough, with- out deranging the digestion. It is an important remedy in diabetes, ^ Codeine is usually isolated from opium by precipitating the aqueous extract by calcium chloride, evaporating and cooling the filtrate, redissolving the deposited crystals of the hydrochlorides in water, and precipitating the morphine by ammonia. From the filtrate, after concentration, the codeine can be recovered by treating by precipitating with caustic alkali, and purified by crystallisation from ether. 2 The hydroxy 1-group in the codeine molecule does not appear to be phenolic, as evidenced by the insolubility of the alkaloid in caustic alkalies, and its negative reaction with ferric chloride. VOL. III. PART II. X 322 DETECTION OF CODEINE. and is also recommended as an hypnotic in mental disease. The official dose is from J to 2 grains. In larger quantities, codeine produces narcotism, often preceded by vomiting and occasionally by purging. Codeine is a strong base, having a marked alkaline reaction, and forming crystallisable, soluble salts, which are neutral to litmus and methyl-orange. The free base precipitates solutions of lead, iron, copper, and certain other of the heavy metals. Codeine Hydrochloride crystallises in radiated groups of prisms containing BHCl+SHgO, soluble in about 20 parts of cold water. The solution is Isevo-rotatory (Sj= —108°). The crystals lose a portion of their water (J aqua) readily, but the remainder is only driven off by many days heating at 100° (Schmidt, Pharm. Jour., [3], xxi. 82), but easily at 120° (Dott). Hence the pro- portion of water in commercial samples of the salt is variable. Codeine Phosphates. The salt BH3PO4-I-2H2O is obtained as a crystalline precipitate by adding codeine to a solution of phosphoric acid till the reaction is only faintly acid, and then adding excess of alcohol. When recrystallised from water the composition is unchanged, but the salt deposited from the solution in hot dilute alcohol contains 2BH3PO4+H2O. Both forms lose their water at 100°, and are met with in commerce, as also a preparation contain- ing excess of phosphoric acid. The usual composition of com- mercial codeine phosphate is B2H3PO4 -|- HgO (Dott). If the salt turn grey or yellow at 100°, the presence of impurity is indicated. The phosphate is said to be the preferable form of employing codeine for hypodermic injections. Detection and Determination of Codeine. In its reactions and general characters codeine presents a strong resemblance to morphine, but is sharply distinguished by its ready solubility in ether and chloroform, and its precipitation by excess of caustic alkali. Codeine does not reduce iodic acid, and gives no coloration with ferric chloride. In strong nitric acid it dissolves to a yellow liquid which should not become red (difference from and absence of morphine). With pure sulphuric acid, codeine gives no coloration, but on warming, or very prolonged standing (several days) at the ordinary temperature, a blue colour is developed. This colour is produced if a trace of nitric acid, ferric chloride, or other oxidising agent be present, an arseniate being the preferable reagent. The blue coloration on warming with sulphuric acid and ferric chloride is apparently common to all ethers of the codeine class. Frdhde's reagent (page 147) is stated by some observers to produce a dirty green colour, soon becoming deep blue, and changing in twenty-four hours to yellow ; according to others, a cherry-red tint, changing DETERMINATION OF CODEINE. 323 to violet, is produced. L. R a b y states that if solid codeine be stirred up with two drops of a solution of sodium hypochlorite, four drops of strong sulphuric acid added, and the whole mixed together, a splendid and persistent blue coloration results. Esculin was the only other substance (of thirty examined) which gave at all a similar reaction. L a f o n uses a solution of 1 gramme of ammonium selenite in 20 c.c. of strong sulphuric acid, which gives a magnificent green colour with traces of codeine. Other reactions are given on pages 302 to 306. Commercial codeine has been met with adulterated with ammo- nium tartrate {Pharm. Jour.^ [3], xiv. 1035), which salt closely resembles it, but is distinguished from codeine by its insolubility in alcohol. Claassen has based a method of determining codeine on the well-known fact that it completely decomposes morphine salts {N.Y. Pharm. Rundschau^ 1890, 40 ; Jour. Chem. Sac, Iviii. 1198). The warm aqueous solution of the free base is treated with excess of morphine sulphate with frequent shaking, and allowed to stand ia the cold for at least twenty-four hours, when the deposited morphine is filtered ofi', dried, and weighed (or titrated). The amount found, multiplied by 0*9868,represents the anhydrous codeine, or by 1 "041 2, the hydrated codeine (CigHgiNOg + HgO). To separate morphine and codeine, the mixed bases, or their salts, are evaporated to dry- ness with excess of magnesia. The residue treated with water, and the liquid shaken repeatedly with ether free from alcohol, the ether distilled off, and the residue exhausted with hot water. In the resultant solution the codeine can be determined as above described. Claassen (loc. cit) has also pointed out that free codeine com- pletely decomposes ammonium salts when heated with them, and has based on the fact a method of determining the alkaloid ; but as morphine behaves in a similar manner, the fact has little practical value. The simplest means of determining codeine and morphine in admixture is to precipitate the solution of the hydrochlorides with acid carbonate of sodium, and wash the dried precipitate with chloroform. The residue consists of morphine. The aqueous filtrate is treated with caustic soda, agitated several times with chloroform, the various chloroform washings and extracts united, evaporated, and the residual codeine dried at 110°, and weighed (D. B. Dott). Pseudocodeine, C;^8H2iN03-f-H20, was discovered by E. Merck in preparing apocodeine {Arch. Pharm., ccxxix. 161). It is a strong base, crystallising in needles melting at 178°-180°. It is 324 APOCODEINE. CRYPTOPINfi, Isevo-rotatory, forms crystallisable salts, gives no reaction with ferric chloride, and has a physiological action similar to, but weaker than, that of codeine. Apocodeine, CigHiglSrOg, is said to be produced by heating codeine hydrochloride with a concentrated solution of zinc chloride for fifteen minutes. It is described as gummy, insoluble in water, soluble in alcohol and ether, and yielding amorphous salts. In physiological action it is a valuable expectorant and mild emetic. Apocodeine gives a characteristic blood-red colour with nitric acid. D. B. D 1 1 doubts the existence of apocodeine, and states that commercial apocodeine hydrochloride is not of a very definite nature, being probably a mixture of an amorphous modification of codeine, polymerised bases, chlorocodide, and apomorphine. The physiological results appear to harmonise with this view {Fharm. Jour., [3], xxi. 878, 916, 955, 996). Methocodeine or Dimethylmorphine, C-^*j'E.^^1^0{0CK^2^ is of interest merely from its theoretical relation to morphine, codeine and thebaine (compare page 296). It is a base forming hard bril- liant lamiuEe melting at 119°, and yields with sulphuric acid a brown coloration, turning violet on addition of water. Cryptopine, C21H23NO3, occurs in but very small quantity in opium, and is precipitated on adding caustic soda to the mother- liquor from which codeine, narceine, thebaine and papaverine have been separated. It crystallises from alcohol in minute six-sided prisms. It is optically inactive, sparingly soluble in boiling alcohol, very slightly in benzene or petroleum spirit, but more readily in chloroform. When freshly precipitated it is soluble in ether, but slowly separates from the solution. (See also pages 301, 304.) Cryptopine and its salts have a bitter taste, and pungent cooling after-taste ; they are hypnotic and mydriatic. Cryptopine salts when dissolved in hot water usually produce on cooling a gelatinous mass, which is gradually changed to crystals. The normal mlphate does not crystallise ; the acid salt gelatinises, as the solution cools, and the jelly shows but slight signs of crystal- lising, even after standing several weeks. The acid oxalate and acid tartrate are very sparingly soluble. Neutral cryptopine meco- nate, {C^^^^O^^C^'Rfi^-\-lOB.cfi, is insoluble in cold, and but slightly soluble in boiling water, and is probably the form in which the alkaloid exists in opium {Pharin. Jour., [3], xviii. 250). Deuteropine, C20H21NO5, an alleged homologue of protopine and cryptopine, requires further examination. Gnoscopine, C34H3gN20ip occurs in the mother-liquors of narceine. When recrystallised from boiling spirit the base forms long, thin, white needles, having a woolly appearance when dried. LANTHOPIKE. LAUDANINE. 326 It melts at 233°, decomposing at the same time, and burns with a smoky flame, leaving a skeleton of charcoal. In pure sulphuric acid, gnoscopine dissolves with slightly yellow colour, which becomes at once carmine-red upon addition of a trace of nitric acid, the colour being permanent. This reaction distinguishes the base from rhoeadine, which becomes red with sulphuric or hydrochloric acid alone (Fharm. Jour., [3], ix. 82). Gnoscopine hydrochloride gives a buff-coloured precipitate with platinic chloride. (See also page 301.) Hydrocotarnine, C12H15NO3, is formed from narcotine, together with meconin, by the action of nascent hydrogen. It volatilises partly unchanged at 100°, and forms readily soluble salts. Lanthopine, CggHggXO^, is obtained from the mother-liquors left from the preparation of morphine by the Kobertson-Gregory process (see page 308). It is a weak base forming no acetate. It is coloured orange-red by nitric acid, and pale violet by sulphuric acid, the latter colour changing to a dark brown on heating. (See also pages 301, 304.) Laudanine, C20II25NO4, occurs with lanthopine. It has re- cently been prepared on a commercial scale by Merck from opium mother-liquors, but the yield is only one-third that of cryptopine. Laudanine crystallises from its solution in boiling alcohol in transparent granules or hexagonal prisms melting at 166°. Laudanine is l8evo-rotatory,tasteless, and poisonous, the hydrochloride being bitter and resembling strychnine in its effects. It resembles morphine in dissolving in caustic alkali solutions, but the sodium- derivative is reprecipitated in glistening white needles on adding excess of caustic alkali. From its solution in caustic alkali lauda- nine is wholly unremoved by chloroform or amylic alcohol, but is extracted if precipitated by ammonia. Its phenolic character is further evidenced by the green coloration yielded with ferric chloride. Treatment with methyl iodide converts laudanine into a base chemically resembling codeine, and distinct from laudano- sine. The solution of laudanine in pure concentrated sulphuric acid has only a very faint pink tint ; the same acid containing iron yields a slightly deeper tint ; but on heating either solution till the acid begins to volatilise, a violet coloration is obtained. With nitric acid, laudanine gives an orange-red colour. Laudanine is a strong base, having an alkaline reaction, and forms well-crystal- lised salts of a bitter taste. BHI is sparingly soluble in cold water, and BHCl easily soluble in water, but nearly insoluble in brine. (See also pages 301, 304.) Laudanosine, C21H27NO4, is homologous with laudanine, but is not produced by heating that base with methyl iodide. Laudano- 326 MECOlirrDINE. NARCEINE. sine is isolated by conversion into its sparingly soluble hydriodide. [t crystallises from benzene in needles melting at 91''. Both the free alkaloid and its salts taste very bitter, and are tetanic poisons. Laudanosine is dextro-rotatory. The solution is strongly alkaline. It gives no coloration with ferric chloride. (See also pages 301, 304.) Morphine, CiyH^gNOg, has already been fully described (page 309). Meconidine, C21H23NO4 (page 301), forms a brownish yellow amorphous mass, soluble with difficulty in ammonia, but readily in caustic alkalies. The base cannot be removed from its solution in caustic soda by agitation with ether, but is extracted from its ammoniacal and lime-water solutions. Meconidine is alkaline in reaction, and nearly destitute of taste ; but yields very bitter, unstable salts. It is very easily decomposed by mineral acids, with production of a rose coloration. It is dissolved by strong sulphuric acid with an olive-green, and by nitric acid witli an orange-red colour. Narceine. C23H29NO9; or Ci3H2oN04.CO.C6H2(OCH3)2.COOH (compare page 299). This base was originally discovered by Pe lie tier, who attributed to it the melting-point 92° C, but Hess e found it to melt at 1 45"". This latter figure, although sub- sequently corrected by Hesse himself, has been generally adopted by compilers, though Glaus and M e i x n e r found 162°; but E. Merck has shown {CJiem. Zeit., 1889, p. 525) that the ordinary commercial alkaloid of English manufacture melts between 150° and 160°, and the pure base at 170°-171°.^ JSFarceine crystallises from water in long white prisms or delicate needles, containing 2H2O, which is driven off at 100°. It has a bitter taste, with styptic after-taste, and powerful hypnotic properties. It is optically inactive. It is very sparingly soluble in cold water or spirit, but dissolves very easily on heating. It is but slightly soluble in chloro- form, and insoluble in ether and benzene. Narceine is precipitated on adding ammonia or caustic potash to solutions of its salts, but dissolves in excess of either reagent, and on addition of a large excess of caustic alkali is reprecipitated as an oily liquid.^ Narceine is a very weak base, the free alkaloid having a very feeble alkaline reaction to delicate litmus ; the solutions of its salts may be titrated with litmus just as if the alkaloid were absent. The acetate is decomposed by water, and the base is said to be extracted by chloroform (but not by amylic alcohol) from liquids containing 1 D o 1 1 states that the meltiDg-point is indefinite, as partial decomposition occurs. ^ Narceine containing a carboxyl-group, its solubility in alkalies is normal, but it seems probable that the oil precipitated by excess of caustic alkali is an alkaline narceinate rather than the free alkaloid. NARCEINE. NARCOTINE. 32T even free mineral acids. BHCl forms needles or sliort stout prisms very easily soluble in water and alcohol, and melting with decomposition at 163°. Narceine liberated from the hydrochloride or other salts by ammonia retains hydrochloric acid with great persistency, and cannot be purified by recrystallisation from water or dilute alcohol. According to E. Merck (Ghem. Zeit, 1889, p. 525 ; Pharm. Jour., [3], xix. 1034; xx. 481) narceine can best be obtained pure by crystallisation from water containing some ammonia or caustic alkali, but a considerable quantity remains in permanent solution. For therapeutic purposes, the presence of a small proportion of hydrochloride is of no consequence, and Merck considers that a preparation free from meconin, and so far freed from basic salt as not to melt below 165°, is sufficiently pure. Chlorine-water, followed by ammonia, gives a blood-red colour with narceine, but many other substances (e.g., tannin) behave similarly. Potassium bichromate gives a crystalline precipitate after some time. Iodine gives a brown precipitate in narceine solutions, but if ammonia be added to remove excess of iodine the precipitate is seen to be blue. Weak iodine solution colours nar- ceine black-blue ; in boiling water a colouiless solution is obtained, but the crystals formed on cooling have a violet or blue colour. Sulphuric acid containing iodic acid gives with narceine a black coloration changing to red (see also page 302 e^ seq.). ''Meconarcein e," according to E. M e r c k, is a preparation of a very variable character, of which one form consists of a yel- lowish liquid containing codeine, narceine, and an unidentified acid soluble in ether, but no meconic acid. In another case the " meco- narceine" formed a white powder melting at 110°, and consisting of a mechanical mixture of narceine and meconic acid, which on adding water combine chemically, and the recrystallised products melt with evolution of gas at 126°, which is the melting-point of acid narceine meconate (Pharm. Zeit., 1889, p. 90). Narootine, CggHggNOy, occurs in opium in very variable quantity, the usual range being from 1*3 to nearly 11 per cent.; but some samples contain traces too minute to be recognised by the usual methods. Narcotine may be extracted from dried opium by ether or benzene, or by the same solvents from the precipitate produced by ammonia in the aqueous solution of opium. ^ It may be separated from narceine by precipitating the solution with excess of ammonia, when the narceine remains in solution. Narcotine crystallises from alcohol or ether in colourless, trans- parent, glittering prisms or groups of needles, which melt at 170°, ^ Opium from which the narcotine has been removed in this manner is now an article of commerce. 328 REACTIONS OF NARCOTINE. and resolidify at 130°, crystallising if cooled slowly. Above 200' narcotine is decomposed into m e c o n i n and cot a mine. ^ It is feebly narcotic, exhibiting poisonous eifects only in somewhat large doses (rS to 3'0 grammes). The solid base is nearly tasteless, but the solutions are bitter. In the free state narcotine is Isevo- rotatory, but the salts exhibit dextro-rotation.^ D. B. D 1 1 has obtained the acetate, sulphate and hydrochloride of narcotine in a crystalline state ; but the first of these salts is almost completely decomposed by solution, the base being precipitated and free acetic acid formed. The same reaction occurs when sodium acetate is added to a solution of narcotine hydrochloride (compare page 306). The hydrochloride and sulphate of narcotine are somewhat more stable, their solutions remaining clear even when largely diluted ; but they react with litmus just as if the acid were uncombined,^ and yield the narcotine to chloroform and similar solvents. These facts prove the basic properties of narcotine to be very feebly marked. Narcotine meconate forms a syrupy solution, which on evapora- tion dries to a varnish which redissolves perfectly in water. The caustic alkalies, alkali-metal carbonates, and ammonia throw down narcotine as a white crystalline precipitate, almost insoluble in cold water and in excess of the precipitants. It may be extracted from the alkaline liquid by chloroform or benzene, or less readily by ether or amy lie alcohol. It is practically unaffected by petroleum spirit (compare page 301). ]N"arcotine is precipitated by the usual alkaloidal reagents, but the reactions are not very characteristic. With potassium thiocyanate it yields a crystalline precipitate readily soluble in acids, even in acetic acid. Iodised potassium iodide precipitates narcotine from extremely dilute solutions. Narcotine may be precipitated and titrated by Mayer's solution (page 139). If a solution of narcotine in dilute hydrochloric acid be treated with bromine, a yellow precipitate is obtained, which dissolves on boiling ; by gradually adding bromine-water, and boiling, a fine rose ^ The constitution and decomposition-products of narcotine are described on page 298. 2 Hesse found for the free alkaloid — Chloroform and Alcohol. Alcohol, Chloroform. Concentration, . , 074 2 2 and 6 Sd, . . . . -185°-0 -191' -5 -207-8 For a solution in * ' benzine " Dott and Peddie found Sd = - 229° (when c was 1 '5), and for a solution in dilute oxalic acid, S© — -*- 62°. ' Narcotine hydrochloride is neutral to methyl-orange (Dot t). OXYNARCOTINE. PAPAVERINE. 329 colour is produced, but is readily destroyed by excess of bromime. The reaction is characteristic. With chlorine-water, narcotine gives a yellowish green colour, turned orange by ammonia. Iodic acid gives no coloration with narcotine. If narcotine be mixed with twice its weight of cane-sugar, and the mixture moistened with strong sulphuric acid, a fine and persistent mahogany-brown colora- tion is produced, said by M. R o b i n to be highly characteristic. {See also page 302.) Opianine, to which the formula CgiHgiNOy is attributed, ia probably merely impure narcotine. OxYNARCOTiNE, CggHggNOg, is Contained in the mother-liquors of narcotine.^ It forms minute crystals, somewhat soluble in hot water, but little soluble in hot alcohol, and insoluble in ether, chloroform or benzene. By oxidation with ferric chloride it yields cotarnine and hemipinic acid. BHCl-t-2H20 forms crystals. (See also page 101.) Papaverine, CgoHgiNO^, is a weak base of feeble narcotic pro- perties. It is separated from narcotine by crystallisation from a strong solution in oxalic acid, the acid oxalate of papaverine being very sparingly soluble. Papaverine crystallises in rhombic prisms or needles, or sometimes in scales. It is sliglitly laavo-rotatory, ^ though its hydrochloride is inactive. The neutral sxtccinate forms large tabular crystals melting at 171°, and soluble in hot water; the benzoate, triclinic crystals melting at 145°, and soluble in alcohol but insoluble in water; and the salicylate, monoclinic crystals melting at 130°. Sulphuric acid containing iodic acid gives with papaverine a purple colour, turning black and green. Dilute solutions of papaverine salts are not precipitated by phospho- molybdic acid. Tincture of iodine, added to an alcoholic solution of papaverine, gives gradually a precipitate of crystalline nciedles. With potassio-iodide of cadmium, papaverine yields a dense white precipitate. (See also page 301 e^ seq.) Papaverosine, found by Deschamps (1864) in the dried seed capsules of the poppy, crystallised in prisms, was soluble in alcohol, ether, chloroform and benzene, and formed a gummy hydrochloride. With sulphuric acid it gave a violet coloration. * Oxynarcotine was first isolated in an impure condition by D. Brown, from crude narceine. This product was purified and analysed by Alder Wright and Beckett. 2 G. Goldschmidt {Monatsch, ix. 42) states that pure papaverine is inac- tive, and suggests that the optical activity of laudanine should be reinvesti- gated, as these two alkaloids constitute the only two known exceptions to the Bel-Van't Hoff theory that derivatives of optically active substances are also active. SIO PROTOPINE. PSEUDOMOEPHINE. PoRPHYROXiNB, described by Merck in 1837 as the red colour-^ ing matter of opium, according to Hesse is a mixture of several bases, one of which is meconidine, and another probably r h 08 a d i n e, which latter alkaloid also occurs in the capsules and other parts of the red poppy. Kanny Lall Dey {Pharm. Jour., [3], xii. 397) states that by treating the aqueous extract of Indian opium with ammonia or sodium carbonate, and immediately agitating with ether, the ethereal solution always leaves on evapora- tion a body (rhoeadine ?) which, when warmed with dilute hydro- chloric acid, gives a rich purple coloration, and he recommends the reaction as a test for Indian opium.^ With Turkey and Smyrna opium no such reaction is obtained. Protopine, C20H19NO5, appears to be the most widely-distributed of all the opium alkaloids. It is found in very minute quantity in opium, but has been met with also in Macleya cordata, Stylo- yhorum dijphyllum^ Sanguinaria Canadensis, and CheUdonium majus. Protopine resembles cryptopine, but the solutions of its salts have a bitter taste, and do not gelatinise on cooling. In small doses, protopine acts on frogs as a narcotic, and in stronger doses paralyses the muscle-substance, and the peripheral ends of the nerves. Upon mammals it has a poisonous action like that of camphor, but differs from it in paralysing the circulating organs. (See also pages 301, 304.) PsBUDOMORPHiNE. Oxydimorphiue. Cg^HggNgOg.^ This alkaloid is best purified by solution in ammonia, from which it crystallises in colourless crusts or delicate silky needles containing 3 aqua. It is a very weak base, forming no acetate, and is without action on vegetable colours. It is tasteless and not poisonous. It dissolves readily in caustic alkalies and milk of lime, but is insoluble in all the ordinary alcoholic and ethereal solvents, as also in dilute sulphuric acid and alkaline carbonates. (Compare page 301.) Its most soluble salt is the hydrochloride, which requires 70 parts of cold water for solution. On adding ammonia, avoiding excess, the alkaloid is precipitated in a crystalline state from the hot, and in a gelatinous state from the cold solution. Hesse finds that when pseudomorphine is mixed with an equal weight of cane-sugar, and 1 Merck repeatedly dips a slip of filter-paper in the ethereal solution, allowing it to dry spontaneously after each immersion. The paper is then moistened with hydrochloric acid and exposed to steam, when it will acquire, especially after drying, a more or less distinct rose-red colour. 2 Pseudomorphine occurs very rarely, having been observed by Hesse in good Smyrna opium only once in four years. It may be prepared by treating morphine with oxidising agents of moderate power, such as potassium ferri- cyanide or dilute permanganate (page 144). RHCEADINE. THEBAINE. 331 strong sulphiiric acid (pure) added, a characteristic dark green coloration is obtained, which gradually turns brown (compare test 5, page 315). If the acid contain a minute quantity of iron, a blue coloration changing to green is produced. Rhceadine, CgiHgjKOg, exists in all parts of the red poppy (Papaver Bhoeas), and in the ripe seed-capsules of the white poppy. It forms small white prisms, which are tasteless and not poisonous. Its solutions in weak acids, avoiding excess, are colourless, but on adding excess of sulphuric or strong hydrochloric acid a purple-red colour is produced. This is destroyed by alkalies and restored by acids, and is so intense that 1 part of rhoeadine will colour 10,000 parts of water purple-red, 200,000 deep rose-red, and 800,000 distinctly red, although only a fraction of the base is converted into colouring matter. The colourless solution of rhoeadine in acids is precipitated by tannin. On adding potassium iodide ta a solution of the acetate, the hydriodide is precipitated as a dense crystalline mass, consisting of microscopic prisms. An aqueous solution of rhoeadine becomes red by prolonged boiling, part of the alkaloid being converted into the isomeric base rhoeagenine (soluble without colour in acids), and on adding a drop of hydro- chloric or sulphuric acid the whole base is decomposed, the solution acquiring a purple-red colour. Cold dilute sulphuric acid converts solid rhoeadine into a colourless resinous mass, which soon dissolves with splendid purple colour, changing to dark purple on boiling, and depositing on cooling small prisms which are brownish red by transmitted and green by reflected light ; while the liquid retains rhoeagenine equal to 99 per cent, of the rhoeadine present, together with the colouring matter. Opium sometimes contains a base which gives the above colour- reactions with sulphuric acid, but it is somewhat doubtful if it is actually rhoeadine. (Compare Porphyroxine, page 330.) Thebaine, C19H21NO3, or 01^1115X0(0.0113)2. Thebaine occurs in opium in proportions ranging from 0"15 to I'O per cent. It crystallises in silvery scales from dilute alcohol, and in needles or hard quadratic prisms from strong alcohol. Thebaine melts at 193°, and is not sublimable.^ It has a sharp and styptic taste, and is a powerful tetanic poison, producing symptoms resembling those due to strychnine. The fatal dose is smaller than that of morphine. Thebaine gives a reddish brown coloration with chlorine- 1 This is Hesse's experience, and is confirmed by Dott. According to other observers, at about 135° it sublimes without fusing, and is deposited in minute crystals resembling caflFeine ; while at higher temperatures, needles, cubes, and prisms are obtained. 332 THEBAINE. TRITOPINE. water and ammonia. Its other colour-reactions (and its solubilities) have already been described. (See page 301 e^ seq.) Thebaine is stated to be extracted (with some difficulty) by chloroform from its acid solutions ; but the statement requires con- firmation, as it is inconsistent with the strongly-marked basic characters of thebaine.^ From narcotine, thebaine may be separated by treating the concentrated acetic solution with excess of basic lead acetate, which precipitates the narcotine only. Dilute acids readily alter thebaine, converting it into the isomeric bases thebenine and thebaicine, which are sparingly soluble in hot alcohol and insoluble in other simple solvents. When heated to 90°, under pressure, with fuming hydrochloric acid, thebaine yields a base having the probable formula C^,jE.^^0{0}l)2, called by its discoverer, W.C. Howard {Ber., xvii. 527; xix. 1596) m o r p h o- thebaine, to indicate its origin and relation to morphine. Tkitopine, 04211^4^2^7' "^^^ isolatcd by Kauder in minute quantity from the mother-liquors of the opium-alkaloid manufac- ture. It resembles morphine and laudanine in being soluble in soda solution, but is reprecipitated in the form of an oil by a large excess of the reagent. Tritopine crystallises in characteristic anhydrous, transparent, needle-like plates melting at 182°, easily soluble in chloroform, but only slightly in ether. With sulphuric acid it behaves like laudanine. It appears to be a di-acid base {Arch. Pharm.y ccxxviii. 419). Opium. Opium is a gummy mass, consisting of the inspissated juice from the incised unripe fruit-capsules of Papaver somniferum, hardened in the air. Opium is produced in Turkey, Asia Minor, Persia, India, China, and other countries, but Smyrna, Constantinople, or Turkey opium is the only variety recognised by the majority of the pharma- copoeias. Persian and East Indian opiums are imported chiefly as sources of the opium alkaloids.^ Chinese opium is wholly con- sumed locally. 1 It is possible that certain thebaine salts are soluble in chloroform (as are those of codeine), and are dissolved as such by agitating their aqueous solutions with chloroform. 2 The variety of poppy cultivated in Asia Minor is said to be the black, which usually has purple flowers, and black, though occasionally white, seeds. It is said to be usually richer in morphia than that from the white- f\ovfeviug and white-seeded poppy, which is rich in narcotine, and appears to be the only kind cultivated in Egypt, Persia, India, China, and Japan. (For a chemical distinction between Turkey and Indian opium, see page 330.) COMPOSITION OF OPIUM. 333 Opium varies considerably in appearance, composition, and quality, according to its origin and mode of preparation.^ Opium is remarkable for the large number of definite, highly com- plex, crystalline principles contained in it. Of these the majority are alkaloids, a list of which is given on page 204. In addition, opium contains acetic, lactic, and meconic acids, the last substance being peculiar to opium. Besides these bodies and the inorganic constituents, opium also contains the indifferent bodies meconin, meconoiosin, and o p i o n i n, and a variety of sugar; together with gummy and pectous matters, albumin, wax, fat, caoutchouc, resin, and a humoid acid. Woody fibre and other extraneous matters are also frequently present ; but genuine opium is wholly free from both starch and tannin. The following may be taken as the general composition of opium : — Per Cent. Morphine, •1 6 to 15, average 8 Narcotine, 4 to 8 Other alkaloids, 0-5 to 2 Meconin, under 1 Meconic acid, .- 3 to 8, average 4 Peculiar resin and caout chouc, - 5 to 10 Per Cent. Fat, .... 1 to 4 Gum and soluble humoid \ acid matters, . . j" 40 to 56 Insoluble matters and mucus, 18 to 20 Ash, .... 4 to 8 Water, 8 to 30, average 20 Alkaloids. Morphine is the most abundant of the bases of opium, and the most valuable of the constituents. Most of the pliarmacopoeias require dried opium to contain not less than 10 per cent, of morphine. Good Smyrna opium deprived of water usually contains from 12 to 15 per cent, of morphine, though cakes from the same case are apt to vary considerably ; but if the proportion be below 10 per cent, on the dry substance, adulteration may be suspected. Egyptian opium is poorer in morphine thpn that from Asia Minor, the proportion ranging from 6 to 12 per cent., but it contains a larger proportion of narcotine. Persian opium is extremely variable in quality, probably partly in consequence of the practice of mixing it with sugar and other adulterants, though much of it is equal to ordinary Turkish opium. East Indian opium is, as a rule, remarkably weak in morphine, the proportion being ^ The product of Asia Minor is described in the British Pharmacopoeia (1885) as follows ; — *' In rounded, irregularly formed, or flattened masses, varying in weight, but commonly about eight ounces to two pounds, usually covered with portions of poppy leaves, and scattered over with the reddish-brown chafiy fruits of a species of Rumex. When fresh, plastic and internally somewhat moist, coarsely granular, and reddish- or chestnut-browu, but becoming harder by keeping, and darkening to blackish-brown. Odour strong, peculiar, narcotic, taste nauseously bitter." 334 ALKALOIDS OF OPIUM. sometimes as low as 2| per cent., more commonly between 3J and 5, and occasionally as high as 8 or 9 per cent. This inferiority is probably partly due to climate and partly to defective methods of ■collection and preparation.^ The variety known as " Patna garden opium" is prepared specially for medical use, and contains from 7 to 8 per cent, of morphine. In Chinese opium, the proportion of mor- phine is generally low. French opium yielded Guibourt from 14*4: to 22'8 of morphine, and German from 165 to 20 per cent. ; that from the white poppy containing, according to B i 1 1 z, 6 '8 per or C, 5H2 \ co.o I Meconin is an indifferent body, crystallising in colourless, shin- ing, six-sided prisms, which melt under water at 77° C, or alone at 110°, and distil at 155°. It is odourless, bitter, and readily soluble in alcohol and chloroform, but only sparingly in ether. V. 845) gave the following analytical results. The proportions of morphine are most probably sensibly below the truth. Ethereal Extract, consisting of Morphine. Description of Opium. Pure Narcotine. Wax. Crude Narcotine. Crude. Pure. 1. Patna, .... 14-2 10-0 4-0 11-2 8-6 2. Indian (1852-53), 12-7 9-0 6-1 11-2 4-3 8. Akbari, . . . 13-5 8-5 5-5 14-2 8-5 4. Behar, . . 13-0 7-6 4-5 10-6 4-6 5. Malwa, 6-5 7-6 4-7 14-4 61 6. Synd, . 9-4 8-0 3-1 8-8 7. Hyderabad, . 10-7 9-7 5-4 '". 3-2 8. Candeish, . ... 7-7 ... 6-1 9. Persian, 14-8 lb"2 6-4 ... 71 10. Egyptian, . 11-5 12-2 8-7 ... 5-8 11. Playford, Suflfolk (1823), 8-8 9-3 6-0 4-3 12. English (1859), . 12-0 11-6 8-1 ... 8-3 Assays of thirty-eight samples of opium, published by M. Adrian, showed a proportion of morphine exceeding 7 per cent, in all but two cases, the average being 10 per cent. The narcotine averaged 2'5 per cent., but bore little relation to the proportion of morphine. A sample showing only 3*87 percent, of morphine contained 3*45 of narcotine, while other samples contained over 10 per cent, of morphine and only the same percentage of narcotine. This variation is doubtless the reason why some samples of opium cause little or no headache and others occasion very disagreeable symptoms. 1 Narceine often occurs more abundantly than thebaine. 336 MECONIN. OPIONIN. Meconin may be readily crystallised from boiling water, in which it is moderately soluble. The meconin contained in opium, in which it exists in the pro^ portion of less than 1 per cent., is probably a decomposition-product of narcotine, from which base it may be prepared by heating with nitric acid. Meconin is extracted from its acidulated aqueous solution by agitation with benzene, chloroform, or amylic alcohol, the first- named solvent being preferable. Meconin dissolves in concentrated sulphuric acid, without at first producing any coloration ; but the solution gradually assumes a greenish tint, changing to reddish in the course of twenty-four hours. If the liquid be then warmed, the colour changes to emerald-green, blue, and purple, finally becoming red. The shades and order of the colours obtained depend much on the proportion of acid used, the tints being bluer and the reaction more delicate with a small quantity. Evaporated with slightly diluted sulphuric acid, meconin gives a green colora- tion. In concentrated hydrochloric acid it dissolves without change of colour, even on heating. If meconin be dissolved in strong sulphuric acid and a minute fragment of potassium nitrate added, a yellow coloration is obtained, rapidly changing to a fine scarlet, which fades slowly and is changed to yellow on heating. The reaction is delicate. An aqueous solution of meconin gives precipitates of characteristic microscopic appearance with iodised potassium iodide and a solu- tion of bromine in hydrobromic acid (T. 6. W o r m 1 e y). Meconoisin, CgHjoOg, was obtained in brown, leaf-like crystal- line masses from the mother-liquors left on the isolation of meconin. When pure it is colourless, freely soluble in alcohol, ether, and hot water, fuses at 88°, and on evaporation with somewhat diluted sulphuric acid yields a red colour, changing to purple. Opionin, according to Hesse, is contained in small quantities in Smyrna opium. It forms white needles which melt at 227° and contain no nitrogen. It is insoluble in water, but dissolves in alkalies, alcohol, and ether. When boiled with milk of lime, opionin is decomposed, an acid being formed which is freely soluble in water and ether, and gives a bulky precipitate with lead acetate in alkaline solutions. Meconio Acid, C7H^07 = C5H02(0H):(C0.0H)2. This sub- stance is characteristic of opium, in which it exists chiefly in com- bination with the alkaloids, but sometimes a portion of it appears to be present in a free state. Meconic acid may be prepared from opium by precipitating the neutralised aqueous solution of the drug with calcium chloride, MECONIC ACID. 337 filtering, and decomposing the precipitate of calcium meconate by repeated treatment with warm diluted hydrochloric acid. A pre- ferable plan is to precipitate the aqueous solution of opium with neutral lead acetate, filter, suspend the precipitate in water, and decompose it with a stream of sulphuretted hydrogen. The filtered and concentrated solution deposits meconic acid on addition of hydrochloric acid. The product may be purified by re-solution in hot water, cooling, and adding hydrochloric acid. Meconic acid may also be conveniently prepared by precipitating it as the calcium salt, decomposing this with a slight excess of oxalic acid, filtering, and concentrating. Meconic acid crystallises in micaceous scales or small rhombic prisms containing 3 aqua. On being heated to 100°, it loses its water of crystallisation and leaves a white effloresced mass. At 120° C. it splits up into carbon dioxide and comenic acid, CgH^Og, which at a higher temperature again loses carbon dioxide, and forms pyromeconic acid, CgH^Og.^ Comenic acid is but sparingly soluble in hot, and is almost insoluble in cold water. In absolute alcohol it is quite insoluble. Meconic acid dissolves in 1 1 5 parts of cold, or 4 parts of boiling water ; its solubility in the cold is diminished by addition of hydrochloric acid, which therefore causes a precipitate in strong solutions. When the solu- tion of meconic acid is boiled for some time, especially if hydro- chloric acid be present, comenic acid is formed, and crystallises out as the liquid cools. The aqueous solution of meconic acid has a sour astringent taste, and strongly acid reaction. Meconic acid is freely soluble in alcohol (distinction from comenic acid) and is deposited in fine crystals on spontaneous evaporation of the solution. It is much less readily soluble in ether and is almost wholly insoluble in chloroform. Nitric acid readily acts on meconic acid, much oxalic acid being formed. Meconic acid derives its chief analytical interest from the fact that it is strictly 'peculiar to opium and its preparations, and hence ^ The relationship between these three bodies appears to be as follows : — (OH (OH roH C5HO2 \ Ct ).0H CgHOa \ H aHOg \ H (CO.OH (CO.OH (H Meconic acid. Comenic acid. Pyromeconic acid. Comenic acid forms prisms, laminae or granules, insoluble in alcohol, soluble in 16 parts of boiling water, but deposited on cooling. Pyromeconic or pyrocomenic acid contains no carboxyl-group, and its acid characters are very feebly marked. It cr3'^stallises in prisms, is readily soluble in water and alcohol, melts at 117°, and boils at 227°, but sublimes slowly at the ordinary temperature and readily at 100°. VOL. III. PART II. y 338 REACTIONS OF MECONIC ACIb. its positive detection is a decided proof of tlie presence of a preparation of opium. It is not poisonous. The microscopic appearance of the precipitates produced in not too dilute solutions of meconic acid or soluble meconates by barium chloride, calcium chloride, potassium ferrocyanide, and hydrochloric acid are highly characteristic. The most characteristic reaction of meconic acid is the forma- tion of a deep purplish red coloration on adding ferric chloride to the solution of meconic acid or a meconate. The shade of colour is distinctly different from that of the ferric acetate or formate, and the ferric meconate also differs from these in not being readily destroyed by boiling, or by adding cold dilute hydrochloric acid, and from the ferric tliiocyanate in being unaffected on addition of mercuric chloride or auric chloride.^ If any doubt exist as to the presence of an acetate, it is desirable to precipitate the neutralised solution with nitrate or neutral acetate of lead, wash the precipi- tated lead meconate thoroughly, suspend it in water, and decompose it with sulphuretted hydrogen. After evaporating the filtered liquid at a gentle heat to drive off the excess of sulphuretted hydrogen, the test with ferric chloride may be safely applied. Instead of adding ferric chloride to the solution of meconic acid, the reagent may be applied to the solid substance, as obtained by the evaporation of its aqueous or ethereal solution. The red coloration produced by meconic acid and a ferric salt is much weakened by oxalic and phosphoric acids, and still more so by metaphosphoric acid, Comenic and pyromeconic acids also strike a red coloration with ferric chloride, but with the latter acid the colour is less deep. Meconic acid may be extracted from its acidulated solutions by agitation with ether, a property which enables it to be readily separated from morphine, acetic acid, tannin, and other substances liable to interfere with the observance of its reaction with ferric chloride. The extraction is not perfect, even when several times repeated, and hence the method cannot be employed for quantita- tive purposes. Meconic acid may be determined by converting it into a lead salt, or colorimetrically by ferric chloride, by comparing the depth of tint produced by the sample with that obtained by treatment with a known quantity of opium. "Very fair approximate estimations of meconic acid, and less accurately of opium, may be made in this way, even when the quantity of material at disposal is very insignificant. Three of the atoms of hydrogen in meconic acid are replaceable ^ Thiocyanates (sulphocyanides) exist in sensible quantity in the saliva (and hence in the contents of the stomach) and also in white mustard. METALLIC MECONATES. 339 by metals, but recent researches have shown that the acid is, pro- perly speaking, dibasic, only two carboxyl groups, CO.OH., being present. The third atom of hydrogen belongs to hydroxyl, and when this is replaced by metals basic salts of a yellow colour result. The metallic meconates are mostly insoluble in water, except the meconates of the alkali-metals. They are nearly all insoluble in alcohol, and are but slightly affected by acetic acid. The salts having two atoms of basic hydrogen replaced by metals are neutral to litmus paper. Acid Calcium Meconate, CaH2[C7H(OH)Og]2, is precipitated as a sparingly soluble salt of characteristic microscopic appearance on adding calcium chloride to not too dilute a solution of meconic acid or a soluble meconate. In presence of free ammonia, less soluble, yellow, dicalcic meco7iate, Ca2[CijrH(OH)Og]2, is precipi- tated. On treating either of these salts with hot dilute hydrochloric acid, meconic acid crystallises out on cooling. Iron Meconates. Ferrous meconate is a colourless, very soluble salt, which turns red on exposure to air. Ferric meconate exists in the purple-red liquid produced on adding a ferric salt to a soluble meconate. Lead Meconate is obtained by precipitating meconic acid or a meconate (or an aqueous solution of opium) with neutral acetate of lead. The triplumbic meconate is stated to be formed even in presence of excess of meconic acid, but it is more probably a mixture or compound of the normal meconate, VhQ>^-H R Ch'.C ^ ■** Ph 02 5^ S? S u S «p. . 53 3.2 g ■S d « S o 00 cS tc "-I 2 pS'2<|ss§ ^^.2 0.2 2 flfl=3 evils' ^i ^=?, aw ce ^.a tion 438. ^ cjM Pi •* 1 triclin lates. low. isms. .,»« ij • S',,^"^ c •S-s>>'S t illl •So + + o tt o 1^ pa '§1 §1 OS °° ' o .-3 I ^1 ^f iililll i •fa CJo 5. «s S e P C5 C5c;5 ci w5 05 s"a .S.S 65 CO |S III.- fi I Illl I'i I '^'^23 li .2 .2 &5 « ^S -2.2 Si §•§ CINCHONA ALKALOIDS. 393 *5 a> a> H 2 a, ■i 5 So n . ® p in n rtJOeS O cS iili < o W D t-i o o § ■* CO oo(N o ooi~-oc6o + "*" + I SS gl§S;3^S8 S gi eS 1^ "Ho, |5 is o o o s\ e\ a* ;z; !z; Jz; ^ S S MAM ^ o^ ^ « « a .5 s -a .5 5a-§a-3g« as 00 gs 6-3 tf ti3.2 394 CINCHONA ALKALOIDS. dicinchonicine, and distinct from the amorphous products formed from the crystallisable bases by the action of heat or acids. In addition to these isomers and anhydro-derivatives of th& cinchona bases, there exist various homologues and isologues of them. Quinine itself is probably a methyl-cupreine and a methoxy-cinchonine. Certain of the cinchona bases (e.g., cupreine) exhibit a remarkable tendency to form stable crystalline compounds with other of the bases. It is probable that the existence of these remarkable compounds, having different physical properties in the form of salts as weU as in the free state, has led to the isolation and description of various bases which will hereafter be found to be compounds. The less important cinchona bases have no recognised position in commerce or medicine, but they are liable to be present to a greater or less extent in specimens of commercial alkaloids called by the better-known names. Commercial quinine is liable to retain traces of cinchonine, quinidine and hydroquinine, and generally contains notable proportions of cinchonidine. Hydro- cinchonidine is sometimes present in commercial cinchonidine^ while quinidine contains hydroquinidine and hydroquinine. Quinamine and conquinamine are probably not unfrequently present in commercial cinchona alkaloids. General Properties of Cinchona Bases. The cinchona alkaloids all have well-defined basic characters, some of them being sufficiently powerfill to displace ammonia from its compounds. Their salts are usually crystallisable. In the free state, the cinchona alkaloids are colourless or faintly- yellow solids, often readily fusible, but not volatile without decomposition. They have generally but little solubility in water, but dissolve more readily in alcohol, and generally with great facility in ether and chloroform. Such as are soluble in the last two liquids are removed from their ammoniacal solutions by agitation with ether or chloroform, but in no case will ether or chloroform remove them from an aqueous solution acidulated with sulphuric or hydrochloric acid. On the other hand, the anhydrous sulphates of many of the cinchona alkaloids are soluble in chloroform, and still more readily in a mixture of chloroform and absolute alcohol. This fact is sometimes utilised for detecting adulterations (p. 417). The solutions of some of the cinchona alkaloids in excess of dilute sulphuric acid exhibit a strong blue fluorescence, which is visible even in very dilute liquids. This fluorescence is destroyed by adding an excess of chloride of sodium or other haloid salt. CHARACTEKS OF CINCHONA BASES. 395 The solutions of the cinchona alkaloids exert a well-marked rotatory action on polarised light, the rotation being in some cases right- and in others left-handed. The specific rotation is affected in a remarkable manner by the solvent employed and by the pro- portion of free acid present, which circumstances greatly reduce the practical value of the optical activity for the identification and quantitative determination of the unmixed alkaloids. On adding a fixed alkali, alkaline carbonate or ammonia to the solution of a salt of one of the cinchona bases, the sparingly soluble alkaloid is usually separated in a free state, and is in some cases soluble in an excess of the precipitant. On agitating the alkaline liquid with chloroform, the precipitated alkaloid is usually dis- solved,^ and may be recovered in a free state by separating the chloroform, and evaporating it to dryness at a steam-heat. By adding more chloroform to the aqueous liquid, and repeating the agitation, the complete extraction of the alkaloid may be ensured, and the process made quantitative (see page 419). Ether may be substituted for chloroform in the case of quinine and other alkaloids readily dissolved by it. The cinchona bases are tertiary amines ; for when treated with an alkyl iodide they form additive-compounds which are converted by treatment with oxide of silver into powerful soluble bases analogous to the tetrethyl-ammonium hydroxide (page 19). Many of the cinchona alkaloids form two series of salts ; neutral (improperly called " basic "), and acid salts. The neutral sulphates of the cinchona alkaloids have, when anhydrous, the general formula BgHgSO^. They have a neutral reaction to litmus and methyl- orange, and are generally very sparingly soluble in water; but the corresponding acid or bi-sulphates (BH2SO4) are generally readily soluble. In some cases still more acid sulphates are known. The sulphates of many of the cinchona bases possess the property of combining with iodine, the compounds produced being in some cases of a very complex character. Certain of tljese *'io do- sulphate s," of which the quinine compound or herepathite is the type, possess the remarkable optical properties of the tour- maline (see page 403). When a salt of one of the natural cinchona bases is heated for a prolonged period to a high temperature, the alkaloid undergoes a curious change. It becomes incapable of crystallising, a property sometimes extending to its salts. The change occurs most readily by exposing the acid sulphate of the alkaloid to a temperature of 100° till anhydrous, and then increasing the heat for some time ^ This is not the case with cupreine and some other alkaloids, which form definite compounds with the fixed alkalies in the same manner as morphine. 396 REACTIONS OF CINCHONA BASES. to about 130" C. No means are at present known by which the modified alkaloid can be restored to its original crystallisable con- dition. When the cinchona bases are heated with strong hydrochloric acid (sp. gr. 1'125) to 150° for six to ten hours, they are converted into apo- or anhydro-derivatives of basic charact.er, the change in the case of quinine and quinidine being attended with evolution of methyl chloride (Hesse, Annal, ccv. 314). When the sulphates of quinine, cinchonine, and cinchonidine are dissolved in concentrated sulphuric acid at the ordinary tem- perature, they are converted into "iso-bases" (Hesse, Annal., ccxliii. 131), which differ in several respects from the parent alkaloids. Hydroquinine, hydroquinidine, and hydrocinchonidine are converted by the same treatment into the corresponding sul- phonic acids, which are compounds of distinct basic character. With platinic chloride, the hydrochlorides of the cinchona bases form chloroplatinates of the general formula BHgPtClg, but many of them also form salts containing B2H2PtClg. Salts of this constitution are produced on adding sodio-platinic chloride to neutral solutions of quinine, quinidine, cinchonidine, and homo- <5inchonidine (Hesse, AnnxiL, ccvii. 922). The auro-chlo- rides of the cinchona bases are mostly unstable, and liable to speedy decomposition with separation of finely-divided metallic gold. Certain of the cinchona bases give a deep green coloration or precipitate when their solutions are treated with chlorine or bromine water, and ammonia subsequently added. This reaction is known as the "thalleioquin test" (see also page 401). Most of the cinchona bases are very completely precipitated by tannic and picric acids, potassio-mercuric iodide, and certain other reagents. These reactions are sometimes used for their detection and separation. On treatment in solution with bromine-water in slight excess, the cinchona bases are converted into bro mo-derivatives. The number of atoms of bromine taken up varies with the con- stitution of the alkaloid. According to T. Fawssett (Pharm. Jour., [3], xix. 915), quinine, quinidine, and cupreine react with approximately Brg, hydroquinine with Br^, and cinchonine, cinchoni- dine, and " amorphous quinine" with Brg. On heating the cinchona bases, or their hydrochlorides or sulphates, with acetic anhydride to about 80° 0. for a few hours, they are converted into acetyl- derivatives (Wright and Beckett, Jour. Chem. Soc, xxix. 655 ; 0. H e s s e , Annal, ccv. 314). With the exception of the acetyl-derivative of quinine, all these compounds are amorphous. They can be dried at 100° without change, are readily soluble in REACTIONS OF CINCHONA BASES. 397 dilute acids, and are thrown down as resinous precipitates by alkalies. On treatment with alcoholic potash they are hydrolysed into acetic acid and the original bases. The acetyl-derivatives of quinine and quinidine give the thalleioquin reaction. The more important properties of the leading cinchona alkaloids may be summarised as follows : — (Hydrated crystals are formed by Quinine, Quinidine, Paytine, Cupi-eine, Cusconine, Chairamine. Anhydi'OiLs crystals are formed by Cinchonine, Cinohonidine, Quinamine. No crystals are formed hy Paricine, Quinicine, Diquinicine, Dicinchonicine. f Readily soluble in Ether : — Quinine, Quinamine, Paytine, Quinicine, Java- nine. Sparingly soluble in Ether : — Cinchonidine, Quinidine, Cupreine. Almost insoluble in Ether : — Cinchonine. 'Dextro-rotatory solutions in alcohol are formed by Cinchonine, Cinchon- amine, Quinamine, Quinidine, Chairamine, Quinicine, Diquini- cine. Lcevo-rotatory solutions in alcohol are formed by Cinchonidine, Hydro- cinchonidine, Homocinchonidine, Paytine, Cupreine, Quinine, Hydroquinine, Cusconine, Aricine. [Fluorescent solutions in dilute sulphuric acid are formed by Quinine, Quinidine, Hydroquinine, Hydroquinidine, Diquinicine. D-( No fluorescence is exliibited by solutions of Cinchonine, Cinchonidine, Hydrocinchonidine, Homocinchonidine, Quinamine, Quinicine, Dicin- chonicine, Cusconine, Cupreine. 'Thalleioquin is formed by Quinine, Quinidine, Quinicine, Diquinicine, Hydroquinine, Hydroquinidine, Cupreine. Thalleioquin is not formed by Apoquinidine, Cinchonine, Cinchonidine, Homocinchonidine, Hydrocinchonidine, Cinchonicine, Dicinchoni- cine, Quinamine, Cinchonamine. Quinine. Quinia. C20H24N2O2; or C9H6(O.CH3)N.C9Hii(OH)KCH3. Quinine is the most important of the cinchona bases, and appears to possess the most powerfully febrifuge properties. Its mode of preparation from the bark is based on the same principles as its determination in the same.-^ ^ The finely-powdered bark is ground to a thin paste with lime, caustic soda, or sodium carbonate, and extracted with warm paraffin oil. On standing the oil separates, when it is run off and shaken with sulphuric acid ; this solution is boiled, and whilst boiling is neutralised with sodium carbonate and allowed to cool. Quinine sulphate crystallises out on cooling, whilst cinchonidine, cinchonine, and quinidine remain in solution as sulphates. The quinine sul- phate is purified by recrystallisation after treatment with animal charcoal. The mother-liquor containing the other alkaloids is treated with caustic soda. 398 CHARACTERS OF QUININE. The chemical constitution of quinine is not thoroughly under- stood, but such knowledge as exists is epitomised on page 168. The complete synthesis of the alkaloid has not hitherto been effected, but cupreine has been apparently converted into quinine by the introduction of a methyl-group.^ Two distinct bodies isomeric with quinine have been synthetically prepared (page 169). Free quinine usually appears as an amorphous or resinous mass. In commerce the free alkaloid is usually met with as a coarse powder, having a brownish yellow tint owing to a trace of colour- ing-matter. It may also be obtained as a fine white powder. From alcohol and some other solvents quinine may be obtained in crystals, but on the evaporation of its ethereal solution it separates as a gelatinous or resinoid mass, which is never crystal- line. This behaviour is important, as most other cinchona bases give crystalline ether-residues. As obtained by the precipitation of one of its salts by an alkali, quinine forms a bulky, white precipitate, which coagu- lates into a resinoid mass by very slight elevation in temperature. According to Q. H e s s e the precipitate at first formed at the ordinary temperature is amorphous and anhydrous, but it soon takes up water and becomes crystalline. It then contains 3 aqua. If the ammonia be added in large excess, and the solution is not too concentrated, the trihydrate is obtained in small needles, and extracted with weak alcohol. Of the three bases precipitated by the alkali, quinidine and cinchonidine are dissolved by the spirit, whilst cinchonine is left behind ; the two former can then be separated by means of their neutral tartrates, that of quinidine being considerably the more soluble. Chemically pure quinine is manufactured by preparing the acid sulphate, which after undergoing sufficient purification is reconverted into the neutral salt. The consumption of quinine amounts to 200,000 kilos, annually. The Ceylon bark yields about 2-4 per cent, of quinine sulphate ; Java bark, 4 to 9 per cent., and even up to 13 per cent. The more recent cultivations of cinchona bark in Peru and Bolivia are of special importance ; such bark yields about 4 to 5 per cent, of sulphate of quinine. —CAew. Zeit, xv. 735. iQrimaux and Arnold, Oompt. Rend., cxii. 774. When a solution of cupreine in methyl alcohol is boiled for several hours under an upright con- denser, with the theoretical quantity of sodium and excess of methyl iodide, a mixture of two iodomethylates was obtained, having all the characteis of the compounds resulting from the similar treatment of quinine. By substituting methyl chloride for the iodide, and operating in a sealed tube at 1 00°, a base was formed, the sulphate of which had all the chemical and physical characters of quinine sulphate, the following reaction having probably occurred : — Ci9N2,N.,0. ONa + CH3CI = NaCl + CisHoiN^O. OCH3 . Sodium compound Quinine, of cupreiue. HYDRATES OF QUININE. 399 and the same compound can be obtained from an ethereal solution below 10°. But the resinoid mass left on the spontaneous evapora- tion of a solution of quinine in ether usually contains water in proportion corresponding to a m o n o h y d r a t e, and when the crystallised trihydrate is exposed in an exsiccator over sulphuric acid, it effloresces and loses its water more or less perfectly. At 20° C, over strong sulphuric acid, the trihydrate soon loses the whole of its water, but over equal measures of strong sulphuric acid and water a monohydrate results. At 15° C, in the open air, the trihydrate is unaltered, but at 20° C. it effloresces and loses 1 aqua, the residue having the composition of a dihydrate. Commercial quinine contains from 8 to 11 per cent, of water, and hence is approximately a dihydrate. The precipitate produced by ammonia at a low temperature in concentrated solutions of quinine sulphate is also usually a dihydrate. Hydrates of quinine con- taining 8 and 9 aqua have also been described. When the tri- hydrate is exposed to a temperature of 40° for a short time, and then to 60°, the whole of the water is driven off, and this change occurs rapidly at 100°. Resinoid quinine loses its water with some difficulty at 100° unless previously powdered, but at 120° becomes anhydrous very rapidly (see Fharm. Jour.^ [3], xvi. 386, 897, 937). Anhydrous quinine, obtained by drying the trihydrate over sulphuric acid and heating to 115°-120°, melts at 171-2°-172°, and that prepared by heating the benzene compound to 120° at 171'6°-172°.i Quinine is odourless. When in solution or finely-divided it has an intense and purely bitter taste. It has valuable febrifuge properties, and is poisonous to frogs and other of the lower animals. It has decided antiseptic properties, retarding or arrest- ing the alcoholic, lactic, butyric, amygdalous, and salicylous fer- mentations, but not the digestive action of pepsin. Quinine is very sparingly soluble in water, according to J. Regnauld the solubility at 15° C. being 1 part in 2024. According to S e s t i n i, however, the solubility of the anhydrous alkaloid in water is 1 in 1667 at 20° and 1 in 902 at 100° C, the trihydrate requiring 1428 and 773 parts of water at the same temperatures. In dilute solutions of the fixed alkalies quinine is not more ^ According to H e s s e {Annal., cclviii. 133) on prolonged heating of a solu- »ion of quinine in alcohol to 30° the alkaloid is converted into an isomeride for which he proposes the unsuitable name of homoquinine. This melts at 174'4''-175°, and is reconverted into quinine by prolonged heating with dilute sulphuric acid. 400 PROPERTIES OF QUININE. soluble than in pure water, but ammonia exercises considerably greater solvent action. Certain ammonium and calcium salts notably increase the solubility of quinine in aqueous liquids. Quinine dissolves in about two parts of alcohol of 0'82 sp. gr., and is still more soluble in boiling alcohol. Crystallised quinine is stated to require from 22 to 30 parts of ether for solution, but freshly-precipitated quinine dissolves in little more than its own weight of ether. Quinine is also very soluble in chloroform (1 : 5), and dissolves readily in benzene^ and carbon disulphide- It is only sparingly soluble in petroleum spirit, even when hot. Quinine exercises a powerful IsBvo-rotatory action on polarised light, the value of Sp being, according to Hesse -145'2° — 0-657 c at 15° C, for the solution of the hydrated alkaloid in 97 per cent, alcohol. In its salts, the optical activity of quinine has different values. Quinine affords no visible colour or other reactions with strong acids. By cautiously dissolving quinine hydrate or sulphate in a mixture of equal volumes of concentrated nitric and sulphuric acids, amorphous dinitroquinine, C2oH22(N02)2N'202, is pro- duced, nearly insoluble in ether and forming uncrystallisable salts (E. H. R e n n i e, Jour. Chem. Soc, xxxix. 469). The action of permanganate and chromic acid mixture on quinine is described on page 168. Quinine is a powerful base, its solutions having a marked alkaline reaction to litmus and methyl-orange, and neutralising the strongest acids. It does not redden phenolphthalein. Detection and Determination of Quinine. The detection and estimation of quinine, when it occurs unmixed with other alkaloids or organic matter, is very readily effected, but the problem becomes more complex in the presence of other cinchona bases. The following reactions are yielded by a solution of quinine in a moderate excess of dilute sulphuric acid : — 1. Solutions of quinine in dilute sulphuric acid exhibit a strong blue fluorescence. The effect is best observed in very dilute liquids, and is intensified by addition of excess of sulphuric acid. The hydrochloride and other haloid compounds of quinine (including the thiosulphate and cyanogen compounds) exhibit no fluorescence till excess of sulphuric acid is added, and the fluores- cence of solutions of the sulphate is destroyed by very small quantities of hydrochloric acid or other chlorides, but can be again produced by adding excess of dilute sulphuric acid. Alcoholic ^ Quinine is deposited from its solution in warm benzene in crystals contain- ing (C2oH24^202)2iC6H6,2aq. {Cfliem. News, xlviii. 4). THALLEIOQUIN REACTION. 401 solutions of quinine exhibit but little fluorescence, and solutions in the alkaloid in immiscible solvents none at all. Under favourable conditions, the fluorescence of quinine becomes an extremely delicate test for the presence of the alkaloid.-^ Fluorescence is also produced by quinidine, hydroquinine and hydroquinidine, and diquinicine, but not by quinamine, cinchonine or its isomers, cusconine, cupreine, or quinicine. 2. According to A. Weller (Arch. d. PJiarm., ccxxiv. 161), on adding chlorine-water to a strong solution of quinine the solu- tion acquires a more or less intense red colour. Bromine-water is a preferable reagent, and on adding a few drops to a saturated solution of quinine hydrochloride a yellow precipitate is formed, which gradually disappears with formation of a rose-red coloration, changing to cherry-red. The colour disappears after a time, but can be reproduced by adding more bromine-water, and the reaction is more delicate and prompt if the quinine solution be previously gently warmed. Acids and excess of bromine-water prevent the reaction, which is also produced by quinidine, but not by cinchonine or cinchonidine. 3. If a solution of quinine, rendered as nearly neutral as possible, be treated first with chlorine or bromine, and then with excess of ammonia, a green substance called thalleioquin is produced, which in concentrated solutions forms a precipitate, and in more dilute a deep green liquid. When carefully applied, the test, which is due to B r a n d e, is extremely delicate. Bromine is a more sensitive reagent than chlorine. The following is the best mode of applying the test : — To 10 c.c. of the solution of quinine add 3 c.c. of chlorine-water, or 0'5 c.c. of saturated bromine-water. Agitate well, and then add one drop of strong ammonia solution, or sufficient to render the liquid distinctly alkaline. If the proportion of quinine exceed about 1 per 1000 of solution, a green substance is precipitated, soluble in absolute ^ Tlie fluorescence of quinine is best observed by holding a test-tube filled with the solution in a vertical position before a window, when a bluish "bloom " will be perceived on observing the liquid from above against a dark background. Another plan is to make a thick streak of the solution on a piece of polished jet or black marble, or on a plate of glass smoked at the back, and to place the streaked surface in front of, and at right angles to, a well-lighted window. The fluorescence of quinine solutions is not perceptible by gas-light, but may be brought out by burning a piece of magnesium ribbon in the proper position. The use of blue glass, which transmits the ultra-violet rays which produce the fluorescence of quinine, while excluding the less refrangible rays, is sometimes recommended. In this case the light transmitted by the glass should be concentrated by means of a lens. VOL. III. PART II. 2 C 402 KEACTIONS OF QUININE. alcohol, but insoluble in ether or chloroform. In more dilute liquids, even if the proportion of quinine does not exceed 1 in 20,000, a deep green coloration is produced. If the green am- moniacal solution be just neutralised with acid, a blue coloration is obtained, and on adding more acid a colour ranging from violet to red, but changing to green again on adding excess of ammonia. H. Trimble has proposed to use this reaction for the approxi- mate colorimetric determination of quinine. He dissolves 0*01 gramme of a quinine salt in 5 c.c. of fresh chlorine-water, and adds 10 c.c. of ammonia solution. The sample is treated in the same way, and the proportion of quinine ascertained from the relative volumes of the liquids when coloured equally intensely. The thalleioquin reaction is also given by quinidine, cupreine, hydroquinine, hydroquinidine and diquinicine, but not byquinamine, or cinch onine and its isomers. It is prevented by morphine. 4. If, after the addition of chlorine or bromine water, the quinine solution be treated with a few drops of solution of potas- sium ferro- or ferri-cyanide, ammonia being subsequently added, a red coloration is produced instead of a green. The reaction is not so delicate as the thalleioquin test, but affords useful confirmatory evidence of the presence of quinine. A. V o g e 1 modifies the test by adding bromine- water and potassium ferrocyanide to the solu- tion to be tested, and then shaking with a fragment of marble, which, in presence of quinine, is at once covered with a red film. Strychnine, cinchonine, and caffeine do not give similar reactions. 5. On adding a fixed alkali, alkaline carbonate, or ammonia to a solution of a salt of quinine, a bulky white precipitate of the free alkaloid (more or less hydrated) is produced. The precipitate is very sparingly soluble in cold water or excess of these precipitants, with the exception of ammonia. The precipitate cannot be conveniently filtered off, washed, and weighed, as it is not wholly insoluble, and melts with very slight increase of tem- perature. Its state of hydration is also very uncertain. But, if the liquid containing the precipitated alkaloid be agitated with ether or chloroform, or a mixture of the two, the quinine passes readily and completely into solution, and may be obtained in the solid state by evaporating the solvent. The process is readily made quantitative by operating with care and repeating the agita- tion with the solvent, and the quinine may be weighed in the anhydrous state as C20H24N2O2, after being dried at 100° C. till constant in weight ; or after exposure for fifteen or twenty minutes to a temperature of 120° C. The determination of quinine in this manner is capable of yielding very accurate results, and is of very extensive and rapid application. TITRATIONS OF QUININE. 403 6. When quinine exists in a free state, as it is obtained in process 5 by the evaporation of its solution in ether or chloroform, it may be determined by titration with standard acid. Each 1 c.c. of decinormal sulphuric acid ( = 4'9 grammes of HgSO^ per litre) corresponds to '0324 gramme of anhydrous quinine. The process is conducted by dissolving the ether-residue in hot alcohol, adding as much water as can be used without causing precipitation, and titrating with decinormal acid. The indicator may be litmus, but methyl-orange or cochineal is decidedly preferable. Sharp readings are obtainable, but extreme care is necessary, owing to the very high combining- weight of quinine (C2oH24N202= 324). When methyl-orange is employed, the alkaloid may be conveniently used in ethereal solution, and in this case previous evaporation, as described under 5, is unnecessary, provided the ethereal solution be washed with water till the aqueous liquid gives no pink colora- tion with phenolphthalein.^ The titration by standard acid, of course, merely indicates the total alkaloid present, in terms of quinine. The process furnishes a very useful check on the deter- mination from the weight of the chloroform or ether-residue, and brings the alkaloid into a convenient form for further examination by one of the following processes : — 7. On adding tincture of iodine to a solution of acid sulphate of quinine in dilute alcohol, a curious compound is produced, called, after its discoverer, Herepathite, and having the formula 4C2oH24N202,3H2S04,2HI,I^4-3aq.2 This body, called also the iodo-sulpha te of quinine or sulphate of iodo- quinine, is the type of a series of similar bodies formed by the action of iodine on the sulphates of the cinchona bases. Here- pathite is but little soluble in cold water or dilute alcohol, and requires 1000 parts of hot water for solution; but it dissolves in boiling rectified spirit, and is deposited on cooling in tabular crystals, remarkable for their dichroism and their action on light, ^ As quinine has no action on plienolplithalein, by the combined use of this indicator and methyl-orange it maybe determined in its salts. Standard xu baryta-water is added to the aqueous liquid until the change of the liquid to yellow or brown shows that the free acid is neutrab'sed. More baryta is then added slowly, with constant stirring, till the production of a pink colour shows that the whole of the acid in combination with the alkaloid is neutralised. Each 1 c.c. of additional ^n alkali required represents 0-0162 gramme of quinine. Tlie process has been used by S e a t o n and Richmond for deter- mining quinine in medicines (Analyst, xv. 43). 2 Herepathite may be readily prepared by dissolving the sulphate of quinine in 10 parts of proof spirit containing 5 per cent, of sulphuric acid, and adding an alcoholic solution of iodine as long as a black precipitate is produced. The preciiiitate is filtered off, washed, and recrystallised from hot alcohol. 404 HEREPATHITE. a thill film of herepathite polarising the transmitted light as completely as the tourmaline. Herepathite is re-converted into sulphate of quinine by treatment with sulphurous acid, thio- sulphates, sulphuretted hydrogen, and other reducing agents. lodosulphate of quinine possesses far less solubility than the corresponding compounds of the other cinchona bases.^ This fact has been utilised by J. E. de Vrij for the determination of quinine (PJiarm. Jour., [3], vi. 461). With the pure alkaloid the method is capable of yielding tolerably accurate results if a correction for solubility be applied, but investigations by A. Christensen, B. Y. Shimoyama and others have shown the process to have a limited practical value, as it is seriously invalidated by the presence of cinchonidine (Pharm. Jour., [3], xii. 441, 1016; xvi. 205; xvii. 654). De Yrij's most recent method of operating is described on page 456. E. B. Stuart (P/iarw. Jour., [3], xii. 1016) finds the here- pathite reaction equally delicate with the thalleioquin test, and quite as easy of application. The salt of quinine should be dissolved in dilute alcohol, and dilute sulphuric acid, the presence of which is essential, added. Very dilute tincture of iodine is then added, drop by drop, with constant agitation, when the precipitate suddenly ^ B. Y. Shimoyama {Tlmrm. Jour., [3], xvi. 205) gives the following figures for the solubility of quinine herepathite in 90 per cent, alcohol at diflferent temperatures : — Temperature ; "C. Alcohol without Acid. Acidulated Alcohol. 15 1 in 869 parts. 1 in 255 parts. 16 ., 841 „ ... 17 ... 1 in 117 parts. 18 „ 101 „ 20 1 in 733 parts. ... 25 „ 660 „ ... 90 ,. 638 „ ... The solubilities of the iodosulphates of the principal cinchona alkaloids in acidulated alcohol at 15° C. were found to be as follow : — Alkaloid. Solubility. Percentage of Iodine. Quinine herepathite, . Cinchonidine, . Quinidine, . Cinchouine, 1 in 255 parts. ., 92 „ » 61 „ >, 42 „ 32-37 53-68 42-70 24-90 QUININE CHROMATE. 405 appears and quickly subsides. Precipitation as herepathite may be used with advantage for separating quinine from morphine even when the relative proportions are as 1 : 1000. 8. In 1862, Andr^ {Jour, de Pharm., xli. 341) described a method of estimating quinine and separating it from other cin- chona bases by precipitation as the chromate, which is stated to be soluble in 160 parts of boiling water or 2400 of water at 15° C, and not liable to alteration by light or on boiling an aqueous solution. A method of assaying quinine, based on the same principle, was described in 1887 by J. E. de Yrij {Arch. Pharm., [3], xxiv. 1073), who attributes to the precipitate the formula (C2oH24N202)2H2Cr04, and states that it is soluble in 2733 parts of water at 12°, or 2000 parts at 16° C. He directs that 5 grammes of quinine sulphate should be dissolved in 500 c.c. of hot water, and a solution of 1'2 gramme of neutral potassium chromate in a little warm water added. After standing in the cold for twelve hours, the precipitate is filtered off, washed with cold water, and weighed after drying in the air. A correction of 005 gramme is made for every 10 c.c. of mother-liquor and wash water. This method has been severely criticised by 0. Hesse (Pharm. Jour.j [3], xvii. 585, 665; xviii. 582), who finds the precipitated chromate of quinine to contain 2 aqua, which fact accounts for some experimenters, working according to de Yrij's directions, having obtained an apparent excess of quinine. On the other hand, cinchonidine and hydroquinine are in part thrown down with the quinine, which renders the method inapplicable for separating quinine from its most constant associates. Quinine is distinguished : — 1. From cinch on in e, a, by its fluorescence; b, its Isevo- rotation ; c, the thalleioquin test ; d, the crystallisation of the sulphate ; e, its solubility in ether ; /, its solubility in ammonia ; g, the sparing solubility of the iodosulphate. 2. From cinchonidine by most of the above reactions, except b, and less sharply than cinchonine by those tests depending on relative solubility (d, e, f, g). 3. From quinidine by &, c?, /, g ; also by (Ji) yielding no precipitate with potassium iodide, and (z) the insolubility of the sulphate in chloroform. 4. From q u i n a m i n e by b, e; j, precipitation as tartrate ; and k^ the sparing solubility of the sulphate. 5. From cupreine by a, and (I) the insolubility of the precipitated alkaloid in excess of soda. Methods for the separation of quinine from the associated cinchona bases are given on pages 411, 453, et seq. '■ 406 QUININE SULPHATE. The separation of quinine from morphine may be effected, as already stated (page 405), by precipitation as herepathite ; also by treating the free alkaloids with chloroform or ether, which leaves the morphine undissolved. From strychnine, quinine may be separated as indicated under "Easton's syrup" (page 377). Salts of Quinine. Quinine is a strong base, completely neutralising acids, and forming crystallisable salts having no reaction on litmus or methyl- orange. These salts react with phenolphthalein as if the acid were in an uncombined state. Quinine also forms a series of acid salts, of which the acid sulphate of quinine is the type. Several of the salts of quinine are official in the Pharmacopoeiay and others are extensively used in medicine. Quinine Sulphate. Diquinic sulphate. (C2oH24N'2^2)2-^2^^4- '^^^^ important salt, sometimes called " d i s u 1 p h a t e " or "basic sulphate" of quinine, forms, in the hydrated state, the ordinary medicinal sulphate of quinine of commerce. Sulphate of quinine is usually met with in exceedingly light scales, or long, flexible filiform needles,^ having a nacreous aspect and a pure and intensely bitter taste. The crystallised sulphate of quinine of commerce usually con- tains about 14"5 per cent, of water, a proportion which corre- sponds closely to a 7-atom hydrate, which requires 14'45 per cent. According to some authorities, however, the wholly uneffloresced crystals contain 8 aqua, or at any rate 7^ aqua.^ H. B. Parsons ^ Chemically pure quinine sulphate, free from h)-droquinine, crystallises in heavy needles resembling sulphate of zinc. The light character of the com- mercial salt is chiefly due to the presence of small admixtures of the sulphates of hydroquinine and cinchonidine, and possibly of hydrocinchonidine and homocinchonidine. One per cent, of cinchonidine is sufficient to produce the light silky appearance, and this persists with a larger proportion. " A few years ago, when the bark of Remijia, which contains no cinchonidine, was first treated, the latter alkaloid was added, as the pure solutions yielded large brilliant needles unfamiliar in commerce ; for the same reason the bark of cuprea was never treated, except by being mixed with other barks." The sul- phates of the bases of the cinchonidine group can be separated from quinine sulphate without interfering with its light form when there is a sufficient amount of hydroquinine present. According to Carles, an addition of 4 grammes of ammonium sulphate to 1 litre of a hot saturated solution of quinine sulphate causes the latter salt to crystallise on cooling in a very voluminous form. ^ The British Pharmacopoeia of 1885 gives the formula of crystallised quinine sulphate as (B2H2S04)2l5H20, which corresponds to 1\ aqua. The freshly prepared salt is stated to lose 15 '2 per cent, of water when dried at the temperature of boiling water. QUININE SULPHATE. 407 {Proa. Amer. Pharm., xxxii. 457) has published the results of drying for three hours, at 100°, 1015 samples of quinine sulphate (taken from tins holding 100 ounces each, and not previously- opened) of American, German, and Italian manufacture. The average loss of water was 13 '8 4 per cent., the highest average from any one maker being 14 "3 6 per cent. A. J. Gown ley {Pharm. Jour., [3], xvi. 797) found the water in thirty-seven samples of commercial quinine sulphate examined during the two years prior to 1886 to range from 8-10 to 16'12 per cent. D. Hooper states that the water ranges from 5 to 1 8 per cent. Hesse {Ber., xiii. 1517) states that pure crystallised quinine sulphate, which has not effloresced, contains 8H2O, or 16*17 per cent, of water. Ginchonidine sulphate, on the contrary, crystallises with 6H2O, or 13*7 per cent. Hence, if a sample of quinine sulphate be dry and quite free from efflorescence, the proportion of water is an indica- tion of its purity. Grystallised quinine sulphate is rendered perfectly anhydrous by* exposure to a temperature of 100° G. If a higher temperature be employed for its dehydration, there is a danger of some of the alkaloid undergoing conversion into quinicine (see page 434). If the anhydrous sulphate of quinine be exposed to moist air, it rapidly absorbs from 4*8 to 5 per cent, of water, a proportion which corresponds to the formula BgHgSO^-fSHgO.-^ On the other hand, the crystallised salt rapidly loses water on exposure to air, until it acquires the composition of the 2-atom hydrate. The same quantity of water is retained when the crystallised salt is dried over sulphuric acid, or crystallised from strong alcohol. Quinine sulphate requires 750 parts of cold water for solution, but dissolves in about 30 parts of water at 100° G. It is far less soluble in water containing sulphate of magnesium, sodium, or ammonium than in pure water. In a strong solution of Rochelle salt, quinine sulphate is so little soluble that the alkaloid can scarcely be detected by the fluorescence or thalleioquin test. On the other hand, the solubility of sulphate of quinine in water is increased by the pre- sence of ammonium chloride, or of potassium nitrate or chlorate. In alcohol, quinine sulphate dissolves more readily than in water, requiring only 7 or 8 parts at a boiling temperature, but it is much less soluble in cold spirit (see "Tincture of Quinine," page 423). Quinine sulphate dissolves in about 24 parts of cold glycerin, the solution being precipitated by addition of water. Crystallised quinine sulphate is not soluble in fixed oils, * H. P. Parsons recommends the official adoption of this hydrate as a definite and stable form of quinine sulphate. 408 QUININE SULPHATE. ether, chloroform, or petroleum spirit. (It is said to dissolve in benzene.) In the anhydrous state, 1 part of quinme sulphate is soluble in about 1000 parts of chloroform (see page 416). In dilute sulphuric acid, quinine sulphate is readily soluble, owing to the formation of acid sulphate of quinine, CgoHg^NgOgjHgSO^. This salt is readily obtainable in crystals containing THgO. The crystallised salt loses 6 aqua in the exsiccator, and becomes anhydrous at 100° C. When heated to about 135° C. it melts, and is converted into the corresponding compound of quinicine (see page 434). Acid sulphate of quinine dissolves in 11 parts of cold water, and more readily in hot water or in alcohol to strongly fluorescent solutions. From a solution of quinine in excess of dilute sulphuric acid, an acid sulphate may be obtained, having the composition ajl^^fi^m^^O,, + THjO (=C2oH2,NA,H,SO, + H,SO, + TH^O). Normal quinine sulphate has a specific rotation in alcoholic solu- tion of Si>= 191*5°, calculated for the anhydrous salt. Excess of acid increases the rotatory power. When dissolved in water acidulated with hydrochloric acid, the value of S^ at 15° is 233*75° (Hess e). Sulphate of quinine is largely employed as a febrifuge and tonic, the official dose ranging from 1 to 10 grains. It has marked antiseptic properties. The fluorescence of sulphate of quinine is considered on page 400 ; its reaction with iodine on page 403 ; and with the thaUeio- quin test on page 401. Examination of Commercial Quinine Sulphate. The salts of quinine, except the tannate (page 420), can all be examined by the following methods applicable to the sulphate of quinine, provided they are first treated with 10 parts of boiling water and their own weight of sodium sulphate. The sulphate of quinine which deposits on cooling and the mother-liquor obtained can then be examined in the usual way. Commercial sulphate of quinine was formerly subject to adultera- tions of a very gross character. Among the bodies employed to sophisticate it are said to have been starch, gum, stearin, salicin, phloridzin, sugars, sulphate of magnesium, sulphate of sodium, chalk, asbestos, boric acid, &c. Some of these additions are apocryphal and the majority are certainly obsolete. Mineral additions would be readily recognised on igniting the sample, which, when pure, will leave no sensible ash. Starch, chalk, stearin, and boric acid would remain insoluble on treating the substance with cold dilute sulphuric acid, and gum would be ADULTERATIONS OF QUININE SULPHATE. 409 precipitated on adding excess of alcohol to the solution thus obtained. Soluble impurities generally may be detected and esti- mated by dissolving the sample in hot water and adding excess of baryta water. The alkaloid is then removed by agitation with ether. After removing the ethereal layer, a stream of carbonic acid is passed through the aqueous liquid to precipitate the excess of baryta, and the whole well boiled and filtered. Sulphate and carbonate of barium will be left insoluble, and the filtrate will con- tain any sugar or other soluble impurity present in the original sample, and the observation of the weight of the residue left on evaporation will allow of a determination of the amount. In presence of sugar the liquid will exert a dextro-rotatory action, and in presence of salicin a Isevo-rotatory action on polarised light. Treatment of the original solid sample with concentrated sul- phuric acid, attended by gentle warming, will sufiice for the quali- tative detection of some impurities. Sugar and mannite will become charred, while salicin developes a striking red colour. Good commercial quinine sulphate dissolves with faint yellow colour in strong sulphuric acid, and the tint is not deepened on warming gently. Similar general impurities may be rapidly tested for by a test devised by Hesse, and described on page 417. Salicin^ if present in greater proportion than 1 per cent., may be detected by this test. The residue insoluble in the chloroform-mixture will be coloured deep red by ccjncentrated sulphuric acid, and will reduce Feb ling's solution after boiling with dilute sulphuric acid. The reaction with strong sulphuric acid will be produced by the original sample if the proportion of salicin be considerable. Smaller proportions of salicin may be detected in the filtrate from the precipitate produced by adding baryta to the aqueous solution of the sample. Another test for salicin is to dissolve 0'25 gramme of the sample in 4 c.c. of water and 4 drops of concentrated hydro- chloric acid. If salicin be present, on boiling the liquid for some minutes a white turbidity will be produced, due to the formation of s a 1 i r e t i n. Sulphate of quinine has occasionally been largely adulterated with or entirely substituted by the hydrochloride of cinchonine. This fraud is recognisable by testing for chlorides with nitric acid and nitrate of silver, and for cinchonine as described on page 413. The most common impurity of commercial sulphate of quinine is an admixture of one or more of the sulphates of other cinchona alkaloids, especially cinchonidine. This admixture is often purely accidental, owing to imperfect separation of the other alkaloids during manufacture, but is no doubt sometimes provided for and 410 COMMERCIAL QUININE SULPHATE. secured by suitable arrangements of the manufacturing operations, while occasionally an intentional admixture of other alkaloids has occurred. Manufacturers of quinine sulphate produce at least four quali- ties of the article. (1) The pure salt or "heavy sulphate," of which the use has been hitherto extremely limited, chiefly on account of its unfamiliarity to the members of the medical pro- fession ; (2 and 3) products satisfying the requirements of the German, and Dutch Fliarmacopmias ; and (4) products satisfying others than the above-mentioned pharmacopoeias, and containing from 4 to 6 per cent, of sulphate of cinchonidine. Other products may have a certain commercial importance, but have no "legal status " in civilised countries. The best samples of commercial quinine sulphate are seldom free from cinchonidine, but contain not more than 2 or 3 per cent. ; whilst other kinds contain from 5 to 10, and even 20 per cent, of cinchonidine sulphate, and on one occasion B. H. Paul found 60 per cent. F. W. Fletcher (1882) states that quinine of English manufacture is usually practically free from cinchonidine, but that certain foreign brands always contain from 10 to 15 per cent., in one case the proportion exceeding 25 per cent. A. J. Cownley has published determinations of cinchonidine made by a reliable process, and finds the proportion to range from nil to 13*9 per cent., the next largest amount being 9"0 per cent. More recently (1889), Paul and Cownley {Pharm. Jour., [3], xix. 665) found the cinchonidine sulphate present in twenty-three typical samples of quinine sulphate, representing all the different makers, to range from nil (in two instances) to 12*34 per cent. In fourteen out of the twenty-three the proportion of impurity was less than 6 per cent. The two samples which were wholly free from cin- chonidine were probably manufactured from cuprea bark, which is characterised by the absence of cinchonidine, and in one instance this conjecture was confirmed by the detection of a trace of cupreine in the sample. In addition, hydroquinine is a very constant impurity in quinine sulphate, a very notable proportion being sometimes present, and, according to Hesse, hydrocinchonidine and homocinchonidine may also be met with in quinine from cer- tain sources. The presence of even 1 per cent, of cinchonine or quinidine in quinine sulphate is far more likely to be intentional than due merely to accident or careless manufacture, but these alkaloids are apt to be met as accidental impurities in quinine hydrochloride. The detection and estimation of foreign alkaloids in commercial ASSAY OF QUININE SULPHATE. 411 sulphate of quinine has received much attention, and considerable ingenuity has been exercised in the solution of this somewhat difficult problem. The recognised methods of testing commercial quinine sulphate for admixtures of other alkaloids are, for the most part, based on the removal of the greater part of the quinine as a sparingly solu- ble sulphate, and the distinction of the remaining quinine from its associates by its greater solubility in ether and its solubility in excess of ammonia. A great variety of tests based on these principles have been devised, especially for recognition and estimation of cin- chonidine, the detection and determination of the other alkaloids when present in notable proportion presenting comparatively little difficulty. The separation of small proportions of cinchonidine from quinine is particularly troublesome, and formerly any considerable propor- tions of the admixture must have escaped recognition. B. H. Paul (Pharm. Jour., [3], vii. 653) has shown that when the test for quinine sulphate prescribed in the British Pharmacopoeia of 1867 is rigidly adhered to, it is difficult to detect an admix- ture of 20 per cent, of the cinchonidine salt. By reducing the volume of ether used, any impurity in excess of 10 per cent, may be detected, but less than this proportion escapes recognition, owing to the property possessed by quinine of increasing the solubility of cinchonidine in ether, or at any rate of preventing the latter from separating in a crystalline state. Hence, for the detection of small proportions of cinchonidine, it is necessary first to separate the greater part of the quinine. This may be done by utilising the fact that quinine sulphate requires about 750 parts of cold water for solution, while cinchonidine sulphate is soluble in 100 parts. This principle was originally employed byKern.er, but its application has been modified and improved in several respects by Paul (Pharm. Jour., [3], vii. 653; xvii. 645), and Hesse (Pharm. Jour., [3], xvii. 975). But cold water does not completely dissolve cinchonidine sulphate from commercial quinine sulphate, according to Hesse, because of its existence in the form of a double sulphate of the two alkaloids. This compound is decomposed or disintegrated by hot water, even if the quantity of liquid be in- sufficient for its solution, the cinchonidine salt passing almost wholly into solution, while the quinine sulphate is for the most part undissolved. On the point whether it is better to treat the sample with water at 60° or to 100° C, authorities are at variance. Hesse considers that at a boiling heat more of the quinine sulphate will pass into solution, and hence there will be a greater tendency to the re-formation of the double salt when crystallisation takes 412 ASSAY OF QUININE SULPHATE. place. Kernel and Weller also recommend the use of water at 60°. E. J u n g fl e i s c h {Jour. Pharm. et Chim., [5], xv. 5 j Fharm. Jour., [3], xvii. 585) gives the preference to a boiling temperature, and points out the tendency to erratic results if less heat be employed. Paul (Pharm. Jour., [3], xvii. 595) con- siders that the best results can only be obtained by using nearly sufficient water to effect the complete solution of the quinine sulphate at the boiling-point. The mode of operating recommended by Hesse is to take 1 gramme of quinine sulphate previously dried at 100°, shake it with 20 c.c. of water at 60° C, filter after cooling, and agitate 6 c.c. of the filtrate in a narrow tube with 1 c.c. of ether and 5 drops of ammonia (sp. gr. 0*96). The clear ethereal solution thus obtained should not deposit crystals on standing. If, on leaving the tube at rest and in a closed condition for two hours, the ethereal stratum be found free from crystals, the sample may be considered pure ; but if it contain more than 0'25 per cent, of cinchonine sulphate, 0*5 of quinidine sulphate, or I'O per cent, of cinchonidine or homocinchonidine sulphate, a distinct separation of crystals wiU occur. The last two impurities appear granular, while crystals of cinchonine and quinidine form concentric groups of delicate needles. If the proportion of cinchonidine be as high as 3 per cent., the separation of crystals will occur immediately, or ■within three minutes ; 2 per cent, will show in about ten minutes ; while with less than 1 per cent, no separation will occur even after twelve hours. ^ To detect smaller proportions of these alkaloids, the cork of the tube should be replaced by a loose plug of cotton-wool, so that the ether may gradually evaporate. On examining the residue with a lens it will appear distinctly crystalline if J per cent, of cinchonidine or homocinchonidine sulphate be present, and a mere trace will be recognisable by the presence of a few crystals in the amorphous mass of quinine. 0*5 per cent, of cinchonine sulphate, or 1*0 per cent, of quinidine sulphate, will cause an almost immediate separa- tion of crystals from the ether. Their presence is far more likely to be intentional than merely accidental or due to careless manufacture. The British Pharmacopoeia of 1885 gives the following methods of testing commercial sulphate of quinine for accompanying ^ A deposit of cinchonidine is recognised by the capillary rising of the pre- cipitate beyond the ethereal layer immediately after shaking the solution. "With a large proportion of cinchonidine a white chalky ring appears at the line of contact of the two liquids. ASSAY OF QUININE SULPHATE. 413 alkaloids.^ The salt " should not contain much more than 5 per cent, of other cinchona alkaloids " : — a. Test for ClncUonidine and Cinchonine. Heat 100 grains of the sample in 5 or 6 ounces of boiling water, with 3 or 4 drops of dilute sulphuric acid.^ Set the solution aside until cold. Separate by filtration the purified crystals of quinine sulphate which crys- tallise out. To the filtrate, which should nearly fill a bottle or flask, add ether, shaking occasionally, until a distinct layer of ether remains undissolved. Then add ammonia in very slight excess, and shake thoroughly, so that the quinine at first pre- cipitated shall be redissolved by the ether. Close the flask, and allow it to stand for some hours, and then remove, with a pipette, the supernatant, clear, ethereal layer which should occupy the neck of the flask. Agitate the residual aqueous liquid and the separated crystals of alkaloid once or twice with a very little ether. Collect the separated alkaloid on a tared filter, wash it with a little ether, dry at 100° C, and weigh. Four parts of the product represent five of crystallised sulphate of cinchonine or cinchonidine in the sample. h. Test for Cupreine. Shake the crystallised sulphate of quinine obtained in Test a with 1 fluid ounce of ether and \ fluid ounce of ammonia (sp. gr. 0*959), separate the ethereal solution, and add to it the ethereal solution and washings obtained in Test a. Shake the united ethereal liquid with IJ fluid ounce of caustic soda solution (10 per cent.), adding water if any solid matter separates. Separate the ethereal layer, agitate the aqueous liquid with more ether, and separate as before. Heat the aqueous liquid to boiling, and exactly neutralise it with dilute sulphuric acid. Allow the solution to cool, separate any crystalline cupreine sulphate by a tared filter, wash with a little cold water, dry and weigh. c. Test for Quinidine. Recrystallise 50 grains of the sample as ^ The French Codex of 1884, making use of Earner's method of analysis, prescribes that 5 c.c. of a mother- liquor obtained at 15° C, after treatment of 1 gramme of the officinal salt with 10 c.c. of luke-warm water, shall remain perfectly limpid for 24 hours after the addition of 7 c.c. of a solution of ammonia of 96 specific gravity. The manufacturers considered these regula- tions severe. However, the new Austrian Pharmacopoeia prescribes the use of 7 o.c of ammonia, which is only slightly less severe a test ; and the pharma- copceias of Russia, Finland, Sweden, the United States, and Japan have adopted nearly the same test. The Dutch Pharmacopoeia has reduced the amount of ammonia to 5 c.c, and the German Pharmacopoeia of 1890 to 4 c.c. 2 This addition of sulphuric acid is objectionable, as tending to increase the solubility of the quinine sulphate and diminish the delicacy of the test. It would be better to direct the addition of just sufficient acid to render the solution faintly acid to litmus. 414 ASSAY OF QUININE SULPHATE. just described in Test a, and to the filtrate add a strong solution of potassium iodide, and a little rectified spirit to prevent the pre- cipitation of the hydriodides of amorphous bases. Collect the precipitate of qiiinidine hydriodide, wash it with a little cold water, dry at 100°, and weigh. " The weight represents about an equal weight of crystallised sulphate of quinidine." The foregoing tests are, of course, not intended for the detection and estimation of minute traces of accompanying alkaloids in quinine sulphate. Cinchonidine has about one-fourth the potency of quinine, and hence the therapeutic value of the preparation is not so greatly affected by a small admixture as is the commercial value. B. H. Paul {Pharm. Jour.^ [3], xvii. 647) points out that the delicacy of the test would be much increased by evaporating the filtered aqueous solution to about one-fifth of its volume before shaking with ether and ammonia.^ Operating in this manner, as small a proportion as 1 per cent, of cinchonidine sulphate can be detected with certainty, even when only 10 grains of the sample is employed, provided that the closed tube (employed with smaU quantities instead of a flask) be allowed to stand for at least twelve hours for the formation of the crystals. De Yrij {Chem. Qentr,^ 1885, 968) has suggested the addition of sufficient sulphuric acid to convert the bases into acid salts before separating them by frac- tional solution and crystallisation. Hesse {Pharm. Jour., [3], xvii. 486), who expresses a high opinion of this method if carefully per- formed, recommends the following mode of operating : — 5 grammes weight of the sample is dissolved by the aid of heat in 12 c.c. of normal sulphuric acid (49 grammes H^SO^ per litre) contained in a small porcelain basin, and the solution poured into a funnel closed at the bottom,^ in which it is allowed to cool. At the end of two hours crystallisation is complete, the stopper is removed, and the mother-liquor allowed to drain away as completely as possible, its removal being assisted by suction. The upper portion of the crystals is then pressed down with a glass rod and washed with 3 c.c. of cold water, added drop by drop while the suction is kept up. The whole solution is then mixed with 16 c.c. of ether (sp. gr. 0"721 to 0*728) and shaken up.^ Three c.c. of ammonia (sp. ^ 111 a later paper {Pharm. Jour., [3], xix. 66,5) Paul and Cownley recom- mend that the solution should be concentrated to about 1 fluid drachm (3^ c.c), and the deposited crystals separated before treatment with ammonia and ether. 2 This may be conveniently eflFectod by a glass rod introduced from above, and having the lower end covered with a short length of india-rubber tubing. The same rod can be afterwards used for pressing down the crystals. 3 If the sample contain more than 10 per cent, of cinchonidine the volume of ether must be increased. ASSAY OF QUININE SULPHATE. 415 gr. 0*960) is next added, and the whole well shaken again. After standing one day the ether is removed witli a pipette, and the crystals which have separated are collected on a filter and washed with water saturated with ether. The filter is then placed on an absorbent surface, the crystals again washed with some ether, and dried at 100°. These crystals are not pure cinchonidine, but a compound of quinine and cinchonidine, having the composition ^20^24-^2^2' ^^19 ■^22-^2^* There is always a certain amount of adhering quinine, especially when the proportion of cinchonidine in the sample is very small, and hence Hesse recommends that the weight obtained should be multiplied by 0'62, instead of by Qid^ which is the calculated factor for the above formula.^ B. H. Paul (Pharm.. Jour., [3], xvii. 555) strongly objects to the acid sulphate test, on the ground that the crystals of acid sulphate are not free from cinchonidine, while the amount of quinine retained in solution is so much increased as to interfere with the subsequent crystallisation of the cinchonidine from ether. Conversion of quinine into and crystallisation as the acid sulphate effects a separation of hydroqidnine, which remains in the mother- liquor, while repeated recrystallisation of the neutral sulphate fails to effect this (compare page 424). A method of assaying quinine sulphate for cinchonidine, based upon the optical rotation of the solution, has been recommended by several eminent authorities and is equally distrusted by others. Oudemans was among the first to experiment in this direction, and Hesse proposed a definite process of assay, based on the rotation of the sulphate. Koppeschaar proposed to employ the tartrates by preference, while R H. Da vies oi)erated on the sulphates. De Vrij has strongly recommended the optical method of examination, giving preference to the tartrates. Jungfleisch and Paul and C o w n 1 e y have expressed strong distrust of the optical method, considering it manifestly impracticable to determine proportions of 1 and IJ per cent, of cinchonidine in quinine sulphate containing even minute pro- portions of the cinchonine and quinidine salts ; and D. Howard states that no published method gives the mixed tartrates of quinine and cinchonidine sufficiently pure to render the polarimetric assay absolutely reliable. Hesse has modified his former high opinion of the method, and points out that it is invalidated by the presence of hydroquinine, which is invariably present in commercial quinine sulphate, and is not separated by converting the bases into tartrates. ^ Hesse's test-experiments on mixtures of pure quinine and cinchonidine sulphates in known proportions justify this euipiiiciil factor. 416 OPTICAL ASSAY OF QUININE SULPHATE. The presence of 1 per cent, of hydroquinine sulphate reduces the rotation to the same extent as 0'42 per cent, of the cinchoni- dine salt, and its presence accounts for the excessive and discordant figures for cinchonidine often obtained by those who rely on the optical method of assay. Hydroquinine cannot be perfectly separated from quinine even by repeated recrystallisations of the neutral sulphate, but it can be completely got rid of by converting the alkaloid into the acid sulphate and recrystallising this from water or alcohol, when the hydroquinine remains in the mother-liquor (compare page 424). For the optical assay, Koppeschaar (Zeitsch. Anal. Chem.y xxiv. 362) recommends that the quinine and cinchonidine should be converted into tartrates by precipitating the neutral solution with Eochelle salt, and the precipitate washed with a little cold water and dried at 125°— 130° C. ; 0*400 gramme of the dry pro- duct is then dissolved in 3 c.c. of normal hydrochloric acid, and the solution diluted with water at 15^ C. to a volume of 20 c.c. The solution is placed in a jacketed tube kept at 15° C, and the rotatory power observed by a polarimeter employing monochromatic (sodium) light. From the angular rotation the specific rotatory power of the tartrate is then calculated by the formula S = — — ; where S is the specific and a the angular rotation, and I the length of the tube in decimetres. From the figure thus obtained, the percentage of quinine tartrate, x, in the mixed tartrate may be ascertained by the following (Koppeschaar's) formula : — _ 100(S-137-67) "'" 82-4 Each 1° of diminution in the specific rotation below 220*07° cor- responds to about 1'2 per cent, of cinchonidine tartrate in the mixed tartrates. The angular rotation is diminished by 0*077° only by the presence of 1 per cent, of cinchonidine tartrate. Notwith- standing the extreme accuracy of observation necessary, Hooper (Pharm. Jour., [3], xvii. 61) has found the optical determination of quinine in the mixed tartrates to give very satisfactory results. Hesse found the specific rotation of quinine, hydroquinine, and cinchonidine tartrates, for Oudemans' concentration B, to be respectively, -212*5°, -176*9°, and -132*0°. For the detection of cinchonine^ or quinidine in quinine sulphate, Hesse proposes to dry the salt at 100° C, and agitate 1 gramme with 15 c.c. of cliloroform free from alcohol. The liquid is passed i According to Laborde {Pharm. Jour., [31, xiii. 684) the presence of cinchonine materially alters the physiological etiects of quinine salts. EXAMINATION OF QUININE SULPHATE. 417 through a small filter. If 10 c.c, on evaporation at a gentle heat, leave an amorphous residue weighing more than '035 gramme, cinchonine or quinidine sulphate is certainly present. If the residue be crystalline and less than the above weight, it may be tested for the foreign alkaloids by heating it with 5 c.c. of water, adding J gramme of potassium sodium tartrate, cooling, filtering from the precipitated quinine and cinchonidine tartrates, and mixing the filtrate with an equal volume of ammonia. If quinidine or cin- chonine be present, a precipitate will be formed, and may be further examined by agitation with ether (see page 412), or by treatment with iodide of potassium (see page 413). Sulphate of cinchonidine, if present, will remain undissolved by the chloroform, but will swell up into very bulky needles, which suck up the chloroform like a sponge and do not yield it again without pressure. L. Schafer {Arch. Pharm., [3], xxv. 64, 1033) has described a method of testing commercial quinine sulphate, based upon the precipitation of the boiling aqueous solution by neutral potassium oxalate. After cooling and filtering, the filtrate is tested by addition of caustic soda. 0. Schlickum (Arch. Pharm., [3], xxv, 128) has investi- gated De Yrij's chromate method (page 405), and finds it appli- cable, under certain conditions, to the examination of quinine sulphate. On precipitating a solution of this or other neutral quinine salt with neutral potassium chromate, and filtering after four or more hours, the filtrate remains clear on addition of soda, if the quinine salt was pure. In presence of J per cent, of cinchonine sulphate, or 1 per cent, of the quinidine or cinchonidine salt, a turbidity is produced at once or after a time. A test for the purity of quinine sulphate, devised by Hesse and adopted by the German Pharmacopoeia, consists in heating 1 gramme of the sample for a short time to 40°-50° C, in 7 c.c. of a mixture of 2 volumes of chloroform and 1 of absolute alcohol. If the sample be pure it is completely dissolved, and the solution remains quite clear on cooling. Sulphates of other cinchona bases and various organic and inorganic impurities remain insoluble (compare page 409). A somewhat similar test has been described by E. H i r s c h s o h n, according to which 0'2 gramme of the quinine sulphate should be briskly agitated with 5 c.c. of a mixture of 30 parts of petroleum ether of 0*680 sp. gr. with 70 parts of chloroform. The liquid is filtered, and diluted with three or four times its volume of petroleum ether, when an admixture of O'l per cent, of sulphates of other cinchona bases will give rise to a turbidity or precipitate. For the detection of amorphous alkaloid in commercial quinine VOL. III. PART II. 2 D 418 QUININE HYDROCHLORIDE. sulphate, De Vrij recommends the following method : — The sample is dissolved in dilute acid, and shaken with ammonia and ether for estimation of total alkaloid. Sufficient decinormal oxalic acid is added to the ether-residue to convert the alkaloid into neutral oxalate, and the liquid is evaporated at a steam-heat and the residue thoroughly dried in the water-bath. It is then dissolved in chloroform, and the liquid filtered if necessary. The clear solu- tion is next treated in a test-tube with a few drops of water, when crystals of oxalate of quinine will appear in the chloroform. If the sample w^ere pure the aqueous layer will remain clear and iincoloured, but if amorphous alkaloid be present it wiU be dissolved by the water and colour it yellow. Quinine Hydrochloride. Hydrochlorate of quinine. B,HC1. This salt forms long asbestos-like prisms containing 2 aqua, which become anhydrous at 120° C. without previously melting. The dehydrated salt fuses at 158°-160° without change, and is not converted into quinicine, as stated by Pasteur (Hesse). If an aqueous solution of quinine hydrochloride saturated at 15° C. be allowed to stand for some time at about 0° C, large octahedral crystals containing 3 aqua separate out. Quinine hydrochloi-ide is soluble in about 40 parts of cold water, and very soluble in hot water and in alcohol. Quinine hydrochloride has been frequently substituted of late years for the sparingly soluble sulphate. Thus it is used in making the Tincture of Quinine, B.P. The hydrochloride is the more expensive salt, owing to the increased difficulty of crystal- lising and the high percentage of quinine contained in it (84*2 per cent., against 73*5 in the crystallised sulphate). Quinine hydrochloride is prepared by reacting on the sulphate with chloride of barium.^ Hence it is apt to contain either unde- composed sulphate of quinine, or else barium chloride. The latter impurity is, of course, very objectionable. Quinine hydrochloride may be assayed in much the same manner as the sulphate (see page 408 et seq.). The B.P. test for quinine sulphate is applicable to the examination of the hydrochloride, if the sample be previously dissolved in ten times its weight of boiling distilled water, together with its own weight of crystallised sodium sulphate. The crystals of quinine sulphate which are deposited, and the filtrate from them, can then be examined as ^ The acid hydrochloride, BHaClg, is obtained by precipitating the acid sulphate of quinine by barium chloride. It forms groups of concentric needles, which can be dried without change at 110°, and are soluble in an equal weight of water. It also separates as a gelatinous mass, which becomes ciystalline on gentle warming. SALTS OF QUININE. 419 described on page 412 e^ seq. The hydrochloride of quinine is more likely to be contaminated with the similar salts of cinchonine and quinidine than with the hydrochlorides of cinchonidine and homocinchonidine. Quinine hydrochloride has on several occasions been accidentally mixed with or replaced by the corresponding salt of morphine. The impurity may be detected by warming the salt with dilute nitric acid, which ac(]uires a yellow or red colour if morphine be present; or the salt may be placed in a porcelain crucible and moistened with very neutral ferric chloride, which will produce a green or blue colour if morphia be present. The production of a blue colour wdth mixed solutions of ferric chloride and potassium ferricyanide (page 317) is also well adapted for the detection and approximate estimation of morphine in presence of cinchona bases. Lastly, the aqueous solution of the salt may be treated with ammonia and agitated with a small quantity of ether, when any morphine (or cinchonine) will remain undissolved. Quinine Hydrohromide, BHBr + HgO, is prepared by mixing equivalent quantities of quinine sulphate and potassium bromide with their own weight of water, adding three or four parts of strong alcohol, filtering from the precipitated potassium sulphate, and crystallising the quinine hydrobromide from the filtrate. The salt forms silky needles, soluble in 16 parts of water to a solution said to be fluorescent (?). Quinine Carbonate, BgHgCOg+HgO, is obtained by passing carbon dioxide into water containing freshly precipitated quinine hydrate, and exposing the resultant solution to the air. It forms translucent needles, efflorescing rapidly in the air, decomposing at 110° C, and soluble in water or alcohol but insoluble in ether. Quinine Clir ornate, B2H2Cr04 + 2H20. The anhydrous salt rapidly re-absorbs 2 aqua on exposure to air. It is soluble in about 2000 parts of cold water, and has been recommended by d e Vrij for the determination of quinine (page 405). It becomes anhydrous at 80", and decomposes at a higher temperature. Quinine Oxalate, BgHgCgO^ + ^HgO, forms delicate needles soluble in about 900 parts of cold water. The oxalates of the other frequently occurring cmchona bases are comparatively easily soluble, and L. Schafer has based on this fact a method of separat- ing small proportions of these boses from quinine (page 417). Quinine Valerate forms colourless rhoraboidal plates, having a pearly lustre and a faint odour of valeric acid. It is not deli- quescent, and fuses at a low temperature. Quinine valerate requires 110 parts of cold or 40 of boiling water for solution, and is easily soluble in alcohol. Valerate of quinine is liable to con- 4.20 QUININE TANNATE. tain much the same impurities as the sulphate (see page 408). Sulphate and hydrochloride of quinine, and valerate and acetate of zinc are also liable to be present. Quinine Tannate has come into use in medicine on account of its comparatively tasteless character. The commercial product varies greatly in its composition, the bitter taste decreasing with the amount of alkaloid contained in the specimen. For the preparation of quinine tannate, P e 1 1 z recommends the precipitation of a saturated solution of 1 part of quinine hydro- chloride by 3 of tannin (in 10 per cent, solution previously neutralised by ammonia). After standing twenty-four hours, the washed precipitate is dried at a low temperature. So prepared, quinine tannate is a yellowish-white amorphous powder, soluble in about 50 parts of cold water or alcohol. Its solution gives the reactions of tannic acid. In some cases, the quinine in the commercial tannate is largely replaced by other cinchona bases. The following analyses by Jobst {Arch. Pharm., [3], xii. 331; Jour. Ghem. Soc, xxxiv. 678) illustrate the composition of commercial "tannate of quinine " : — 1 2 3 4 5 6 7 Water lost at 120° C. 7-2 97 9-1 9-8 10-2 10-7 11-4 Quinine, Quinidine, . Cinchonidine, Cinchouine, Total Alkaloid, . 31*37 22-72 4-46 11-97 7-33 4-93 2-43 13-10 3-35 6-23 Trace. •23-80 Trace. 10-00 7-40 31-37 22-72 23-76 23-82 27-03 10-00 7-40 To ascertain the proportion of total alkaloid in quinine tannate, Jobst powders 1 gramme of the sample, and mixes it with milk of lime. The mixture is dried on the water-bath, and the resulting powder exhausted with chloroform. The chloroform is filtered, evaporated, and the residue weighed after drying at 120° C. The alkaloid thus separated can be further examined as described on page 412. There seems no reason why the mixture of the sample with milk of lime should not be agitated directly with chloroform, thus avoiding the evaporation to dryness of the aqueous liquid. A similar process is adopted by S. Neumann, who agitates the finely divided tannate with strong solution of caustic alkali and excess of ether. The presence of solid particles CITE ATE OF IRON AND QUININE. 421 in suspension, either in the ethereal or alkaline solution, shows that the sample is impure or that it has not been completely decomposed. 8. Qpdnine Tartrate, BgHgC^H^Og + HgO, forms a crystalline precipitate, soluble in 910 parts of cold and more readily in hot water. It becomes anhydrous at lOO'', and is the best form for observing the optical activity of quinine (page 416). Citrate of Qninme is not a commercial preparation, but in com- bination with ferric citrate it constitutes the Ferri et Quinince Citras, B.P. Citrate of Iron and Quinine occurs in commerce in the form of thin transparent deliquescent scales, varying in colour from a delicate greenish golden yellow to yellowish brown, according to the proportion of ammonium citrate present. The preparation should be somewhat slowly, but freely and completely, soluble in cold water. It is insoluble in alcohol or ether. The aqueous solution has a very bitter and chalybeate taste, and should be only very slightly acid. On adding ammonia to the cold solution, white quinine hydrate is thrown down, and the liquid assumes a darker colour. No ferric hydrate is precipitated unless the liquid be heated, or a fixed alkali substituted for the ammonia. Citrate of iron and (.quinine is liable to several sophistications. The proportion of water in the sample may be ascertained by drying a weighed quantity in the water-oven. It averages 8 per cent., and should not exceed 10 to 12 per cent. Adulteration with jpotassio-citrate or potassio-tartrate of iron would be detected by the strongly alkaline reaction of the residue left on igniting the substance, a genuine preparation yielding an ash neutral or only very faintly alkaline to litmus paper. The substitution of tartaric acid for the citric acid of the sample is now improbable, but may be detected as described in Volume I. The proportion of oxide of iron can be estimated in the pure preparation with sufficient accuracy by igniting a known weight of the sample. After testing the ash for fixed alkali, a few dro])s of nitric acid should be added and the residue again ignited. This treatment ensures the complete combustion of the carbon. Citrate of iron and quinine ought to yield from 18 to 20 per cent, of ferric oxide on ignition. A more accurate estimation of the iron can be made in the ash, if desired. Excess of citric acid is indicated by the extra acidity of the sample, but the commercial substance frequently contains a much larger proportion of acid than is prescribed in the British Phar macopoeia. Sulphates ale almost invariably present in citrate oi iron and 422 CITRATE OF tRON AND QlTINmE. quinine, owing to imperfect washing of the ferric hydrate em- ployed, or to the introduction of the quinine as sulphate instead of precipitated hydrate. The employment of sulphate of quinine is said to render the preparation liable to yield a turbid solution, but it has the advantage of preventing the inevitable loss of alkaloid attending the preparation of quirdne hydrate.^ The British Pharmacopoeia of 1867 required that the citrate of iron and quinine should contain 16 per cent, of alkaloid, as deter- mined by drying, at an unstated temperature, the unwashed quinine hydrate precipitated by ammonia. In the edition of 1885, tliis faulty process was substituted by a method recommended by the author {Analyst, i. 22), based on the li iteration of the quinine from the aqueous solution by ammonia and extraction of the alkaloid by ether or chloroform.^ No temperature is prescribed for drying the alkaloidal residue, but a constant weiglit is best obtained at 110°— 120°. By this process, which yields very accurate results, the B.P. preparation is now required to yield 15 per cent, of alka- loid.^ If preferred, the residue may be dissolved in a little alcohol, the solution diluted with water, and titrated with a standard mineral acid and methyl-orange. The proportion of alkaloid in the citrate of iron and quinine of commerce is often notably less than the 15 per cent, required by the British Pharmacopoeia (see Pharm. Jour., xvii. 234 ; xix. 259 ; XX. 1052). Very commonly only 13 per cent, is present,* and ^ F. W. Fletcher states that a preparation made with sulphate of quinine contains less lime salts than when quinine hydrate is used, since the lime salts introduced in the water employed for washing the alkaline ferric hydrate are retained by the latter, and are subsequently precipitated as calcium sul- phate, instead of remaining in the finished product. * To ensure accurate results, the cold solution of the sample must be treated with a considerable excess of ammonia ; the volume o4" ether or chloroform used should equal that of the animoniacal liquid, and the agitation should be conducted imuieiliately ; the treatment with the solvent should be repeated ; and care must be tiiken that the whole of the precipitated alkaloid is dissolved by the ether. This occurs instantaneously with pure quinine, but if cincho- nine has been substituted it will remain undissolved. In such samples, the treatment with ether should be followed by agitation with a mixture of 4 parts of chloroform and 1 of amylic alcohol. ^ The original issue o f the 1885 edition of the British Pharmacoposia required 16 per cent, of quinine, as estimated by the ammonia-ether process, but the criticisms of F. W. Fletcher, C. Umney, and others {Pharm. Jour., [3], 263, 406) showed that, if prepared according to the official directions, this proportion was impossible, and the amount was subsequently reduced to 15 per cent. ^Chas. Umney {Pharm. Jour. , [3], xvii. 235) considers that, the B. P. standard of quality being easily attainable, the manufacture of citrate of iron TINCTURE OF QUININE. 4231 occasionally (in the author's experience) from 9 to 11 per cent., even in the case of preparations manufactured by English firms of fairly good repute. Foreign specimens sometimes contain only 4 or 5 per cent, of alkaloid, and that not quinine. The adulteration of citrate of iron and quinine is not limited to deficiency of total alkaloid, the quinine being sometimes replaced, without acknowledgment, by other cinchona bases. The British Pharmaco;pceia prescribes no test for these, further than requiring the ether-residue to be " almost entirely soluble in a little pure ether." The presence of these bases is best detected by dissolving the alkaloidal residue in sufficient dilute sulphuric acid to convert the bases into neutral sulphates,^ and treating the resultant solution as described on page 4 1 2 e^ seq. To obtain reliable results a consider- able quantity of the sample must be employed, but nearly the whole of the quinine is subsequently recovered as crystallised sul- phate. By separating this on a calico-filter, pressing it between folds of blotting-paper, and drying it at 100'', the anhydrous sul- phate is obtained, and its weight multiplied by 1'18 represents the weight of the crystallised salt. If to this amount there is added 0'00133 gramme for each 1 c.c. of mother-liquor, a very fair direct determination of the quinine sulphate will be obtained ; and by multiplying^ the result by '735 the corresponding amount of free quinine will be found. in foreign specimens of citrate, substitution of the quinine by other cinchona bases is common. Amorphous alkaloids are not unfrequently present in considerable proportion. Tincture of Quinine, B.P., was formerly directed to be made by dissolving 160 grains of crystallised sulphate of quinine in 20 fluid ounces of tincture of orange-peel, by the aid of a gentle heat, the solution being filtered after three days. This was an unsatisfactory preparation, as in cold weather, or when too weak a spirit was used, it was apt to deposit crystals of sulphate of quinine, and so alter in strength. In some cases, at least, the deposit con- sisted largely of calcium sulphate. In the Pharmacopoeia of 1885 an equal weight of quinine hydrochloride is substituted for the sulphate, so that the tincture is somewhat stronger than the old preparation. To determine the proportion of quinine in the tincture, and quinine containing only 13 per cent, of alkaloid, unless it arises from some accident, is a disgrace to pharmacy ; and that any pharmacist who sells an article of tliis character ought to be punished, unless he can show good cause for the deficiency. 1 This may be effected by adding a moderate excess of hot dilute acid, and then dilute ammonia, drop by drop, until the liquid is neutral to methyl- orange or litmus. 424 HYDROQUININE. 1 fluid ounce should be concentrated, and shaken with ether to remove the essential oil of orange-peel. After removing the ether, the aqueous liquid should he cooled, an excess of ammonia added, and then the whole shaken with ether in the usual way (see page 402). Wine of Quinine, B.P., contains 1 grain of crystallised sulphate of quinine and 1 J grain of citric acid in each fluid ounce of orange wine. It is apt to be debased by partial omission of the quinine or its replacement by other cinchona alkaloids. For its assay, 2 fluid ounces may be concentrated to J ounce, and then treated like the tincture of quinine (see above). If the alkaloid prove insoluble in ether, a mixture of chloroform and amylic alcohol must be substituted for the ether. More reliable results are obtained by titrating the ether-residue with standard acid and methyl-orange than by weighing it, as substances other than alkaloids are liable to be extracted. Hydroquinine, CgoHggNgOg, was discovered by Hesse {Ber., xv. 856) in the mother-liquors from which quinine sulphate had been crystallised, and subsequently in the commercial salt itself, in which it is sometimes present to the extent of 4 per cent.^ Quinine cannot be perfectly freed from hydroquinine even by repeated crystallisation of the neutral sulphates, but the hydro- quinine can be completely separated by converting the alkaloid into the acid sulphate and recrystallising this from water or alcohol, when the hydroquinine remains in the mother-liquor. As precipitated from a cold solution of a salt by caustic soda, hydroquinine is amorphous, but gradually becomes crystalline. In the latter condition it contains 2 aqua, which is driven off at 115°. From chloroform and ether the alkaloid crystallises in delicate concentric groups of needles. It melts with darkening at 168°. Hydroquinine dissolves readily in alcohol, ether, chloroform, benzene and ammonia, but not in caustic alkali solutions, and is only very sparingly soluble in water. Hydroquinine resembles quinine in its IsBvo-rotation, fluorescence of its acid solutions, behaviour with the thalleioquin test, and in its physiological action. It diff'ers from quinine by only very slowly decolorising a solution of potassium permanganate. Crystalline compounds of hydroquinine with cupreine, quini- ^ The proportion of hydroquinine in the bark is very small, and bears no constant relation to that of the quinine. To obtain the hydroquinine pure the alkaloids should be repeatedly crystallised as acid sulphates, the residual quinine got rid of by potassium permanganate, the hydroquinine liberated from the filtered liquid by caustic soda, extracted with ether or chloroform, and the neutral sulphate repeatedly recrystallised from boiling water. QUINIDINE. 425 dine, cinch onidine, and some other cinchona bases have been obtained ; but not with cinchonine or hydrocinchonine. Hydroquinine has the usual well-marked basic characters of the cinchona alkaloids. BgHgSO^ + GHgO forms short prisms, soluble in 350 parts of cold water. The tartrate crystallises with 2 aqua in prisms which become anhydrous at 120° and are soluble in 545 parts of water at 17° C. The chromate is more soluble than the quinine salt, but crystallises with it, and can only be partially separated by boiling with water. BHCl + 2 aqua is readily soluble. On mixing its solution with l^otassium iodide, the liydriodide separates as an oily mass which gradually solidifies but does not become crystalline. The acid saltj B(HI)2+4aqua, crystallises in brilliant yellow needles, readily soluble in hot water to a colourless solution, from which the yellow salt separates again on cooling. When heated to 140° with strong hydrochloric acid, hydro- quinine loses a methyl group, and is converted into h y d r o c u- preine, C19H24N2O2. When hydroquinine is heated to 140° with sulphuric acid con- taining 25 per cent, of HgSO^ the alkaloid is unchanged ; but when the dry sulphate is fused by heating it to 140°, the base is converted into amorphous hydroquinicine without altera- tion of weight or other change of composition. Hydroquinicine neutralises acids completely and forms some crystallisable salts. When an ethereal solution of the base is gradually mixed with a solution of oxalic acid in ether, neutral hydroquinicine oxalate is formed as an amorphous brown mass, readily soluble in chloroform ; whereas the oxalate of qui- nicine, obtained similarly, forms a voluminous precipitate, consist- ing of very minute needles. Hydroquinine- sulplionic add, C^^^^{^Ofi)l^jd^-\-^jdi is ob- tained on dissolving hydroquinine in cold concentrated sulphuric acid. On diluting the solution with water and neutralising it with ammonia, the sulphonic acid separates in crystals, insoluble in ether or chloroform and sparingly soluble in cold soda or ammonia. In dilute acids it dissolves readily, forming crystallisable salts. The sulphuric acid solution is fluorescent and responds to the thalleioquin test. Quinidine. Conquinine. C2oH24N2^2- This base is isomeric with quinine, and occurs frequently in cinchona barks (especially Cinchona Pitayensis) in association with quinine and other alkaloids. It also occurs in cuprea bark ; and is present to a considerable extent in commercial " quinoidine." 426 QUINIPINE SULPHATE. Quinidine (see also page 393) crystallises from alcohol with 2 J aqua in large monoclinic efflorescent prisms or needles. From ether permanent rhombohedra containing 2 aqua are obtained, and from boiling water permanent plates with 1 J aqua. The whole of the water is driven off at 120°. At 160° the anhydrous alkaloid begins to brown slightly, and melts at 168°. Quinidine resembles quinine in its taste and physiological effects, in being deposited in hydrated crystals from alcohol, in its tolerably ready solubility in ether, in giving the thalleioquin reaction, and in the fluorescence of its solution in dilute sulphuric acid. It is distinguished from quinine by the permanent bulky precipitate its solutions yield on successive treatment with chlorine water, potassium ferricyanide, and ammonia ; and also by the very sparing solubility of its hydriodide. Quinidine Sulphate^ B2H2SO^+2H20, crystallises in white needles or long hard prisms which require about 100 parts of cold or 7 of boiling water for solution. It dissolves in 7 parts of cold alcohol, and in 20 of chloroform, but is almost insoluble in ether. The salt differs from the sulphates of the other cinchona alkaloids in requiring a temperature of 120° to render it anhydrous, and in readily taking up the water again in moist air. Quinidine sulphate is an official remedy in the United States and France. It is examined for other alkaloids by a test slightly modified from one devised by de Vrij {Pharm. Jour., [3], viii. 745), who utilises the fact that quinidine hydriodide requires 1200 parts of water for solution. To test the purity of the commercial sulphate of quinidine, 0'5 gramme is dissolved in 10 c.c. of water at 60° C, and an equal weight of iodide of potassium free from any alkaline reaction added. If the sample be pure, hydriodide of quini- dine is precipitated on stirring and cooling as a heavy sandy powder, and if the liquid be allowed to stand for half an hour with frequent agitation and is then filtered, addition of one or two drops of ammonia will cause no turbidity in the clear filtrate. A slight turbidity indicates a trifling admixture of other alkaloids, but if a decided precipitate occur the alkaline liquid should be shaken with a mixture of amy lie alcohol and chloroform (see page 431), or chloroform only, and the solvent evaporated to ascertain the proportion and nature of the admixture, which may be cinchonidine or quinine, but is usually cinchonine. The appearance of the precipitated hydriodide is sufficient indication of the presence of impurity, as in the presence of cinchonine or cinchonidine it is resinous instead of being sandy. For the detection of inorganic impurities {e.g., calcium or sodium compounds) in commercial quinidine sulphate, Hesse treats one QUIN AMINE. 427 gramme of the sample with 7 c.c. of a mixture of 2 volumes of chloroform with 1 of alcohol of 95 per cent. Complete solution will take place in the absence of impurities. The presence of cinchonidine sulphate in the quinidine salt may- be detected by treating the sample with pure chloroform. Unless only a very small proportion of the impurity be present, part of it will remain undissolved. Smaller quantities may be detected by shaking the chloroform solution with cold water, in which the whole of the cinchonidine and part only of the quinidine salt will dissolve, and the former will be precipitated on addition of Eochelle salt. A solution of quinidine sulphate in chloroform is at first colour- less, but on keeping becomes yellow with a slight green reflection. Quinamine. CigHg^NgOg. This alkaloid was first discovered by Hesse in the bark of Cinchona succwubra, and has since been detected in O. officinalis^ rosulenta, and several varieties of Cinchona Calisaya, particularly Ledgeriana.^ Quinamine crystallises in delicate hair-like anhydrous needles, which melt at 172° C. Its rotatory power in alcoholic solution is-f 104*5° for the sodium ray. Quinamine is nearly insoluble in cold water, more readily in boiling. Hot alcohol dissolves it freely. It also dissolves in boil- ing ether, petroleum spirit, and benzene. Quinamine itself is almost tasteless, but its solutions in acids are very bitter. The solution in excess of dilute sulphuric acid exhibits no fluorescence. Acid solutions of quinamine are very prone to decomposition with formation of an amorphous alka- loid called quinamidine, isomeric with quinamine. Q u i n- amicine is also formed as a bye-product, and under certain conditions apoquinamine, C19H22N2O, results. When tested with chlorine or bromine water and ammonia, solutions of quina- mine yield a yellowish amorphous precipitate, but no green colour. The solid alkaloid, when moistened with strong nitric acid, gives a yellow coloration. CoNQUiNAMiNE, C^gHg^NgOg, occurs with quinamine, but in 1 The motlier-liquors from the crystals of quinine siilphate are precipitated with Rochelle salt, the filtrate treated with ammonia, and the precipitate washed with ether. The ethereal washings are treated with acetic acid, the liquid neutralised, and while warm treated with potassium thioeyanate, till on cooling cinchonine can no longer be detected. Quinidine is then precipitated, together with colouring matter. The filtered liquid is treated with soda, and the resinous precipitate dissolved in a minimum of hot 80 per cent, alcohol, from which quinamine crystallises on cooling. 428 CONQUINAMINE. smaller proportion. It may be separated from the latter base by fractional crystallisation of the nitrates, oxalates, or hybromides, the conquinamine salts being in each case the less soluble (An7ialen, ceix. 38, 62). Conquinamine forms colourless or golden-yellow tetragonal crystals, melting at 121°-123°, easily soluble in ether, chloroform, and benzene. Sd = + 204 "1° for a 4 per cent, in alcohol. M2'il2SO^-\-x aqua is very soluble. The aurochloride is a yellow precipitate, becoming purple. Conquinamine closely resembles quinamine. When heated with concentrated hydrochloric acid, it yields apoquinamine, CigHggNgO. Cinchonidine. CigHggNgO.i (See also page 392.) This base is contained in several species of cinchona, but is especially characteristic of the red bark of C. succiruhra. Accord- ing to D. Hooper the absence of cinchonidine is a distinctive character of Remijia barks. It was formerly called q u i n i d i n e. Cinchonidine crystallises in short anhydrous prisms or thin plates, soluble in 16 parts of alcohol and 188 of ether. It is readily soluble in amylic alcohol and chloroform. It is laevo-rotatory, Sp (where c = 4 and ^=15° C), in chloroformic solution being — 70*0°; while in dilute hydrochloric acid solution (c = 5) Sd= - 174"6.° Cinchonidine resembles quinine in the direction of its optical activity, in the insolubility of the anhydrous neutral sulphate in chloroform, and in the sparing solubility of the tartrate in water. According to Hesse, it forms a crystalline compound with quinine containing C20H24N2O2 + 2C19H22N2O. It is distinguished from quinine by its lesser specific rotation, its more sparing solubility in ether, its non-fluorescence, by not giving the thalleioquin reaction, and by the greater solubility of its neutral and acid sulphate and iodosulphate. The accurate separation of cinchoni- dine from quinine presents great difficulties, and is discussed at length on page 411 et seq. Cinchonidine has only about one-fourth of the therapeutic activity of quinine. Cinchonidine is isomeric with cinchonine, from which it differs by its Isevo-rotation ; its greater solubility in ether ; the insolubility of its tartrate in water ; the insolubility of the anhydrous sulphate in chloroform ; and the formula of the crystallised sulphate. The normal salts of cinchonidine are neutral to litmus and methyl- orange, but acid to phenolphthalein. Thus the precipitated tartrate ^ Cinchonidine was formcrl\' believed to contain C20H24N2O ; but its con- version by heating with concentrated hydrochloric acid into apocinchoni- dine, C19H22N2O, without formotion of methyl chloride, and analyses of hydrochloride, sulpliatc, and chloroplatinate establish the formula given in the text. CINCHONIDINE SALTS. 429 reacts to the last indicator like an equivalent amount of free tar- taric acid, and the combined alkaloid can be estimated by titration in presence of alcohol with standard caustic soda or baryta. Adhering Rochelle salt does not interfere. The following table shows the formulae and solubilities of the principal salts of cinchonidine : — Salt. Formula. Appearance. Solubility in Water. Cold. Hot. Hydrochloride, Hydrobromide, Sulphate, . Oxalate, . . Tartrate, . BHCl+laq. BHBr+1 aq. B2H2SO4+X aq. B2H2C2O4+6 aq. B2C4HeOo+2 aq. Double pyramids or octahedra. Long colourless needles. Silky lustrous needles, or thin quadratic prisms. Prismatic crystal- line powder. Crystalline pre- cipitate. 30 40 100 252 at 12° 1265 at 10° Readily soluble. Freely soluble. 4 ! ... Cinchonidine sulphate, B2H2SO4, is remarkable for the number of hydrates it is capable of forming. From a moderately con- centrated aqueous solution it crystallises with 6 aqua in brilliant needles ; from a hot and concentrated aqueous solution in hard prisms or acicular silky crystals containing 3 aqua (official in the B. and U.S. Pharmacopoeias)', and from alcohol in fine prisms with 2 aqua. A hydrate containing 5 aqua has been described by Hesse. ^ The 6-atom hydrate is somewhat efflorescent. All water is lost at 100°, and 2 aqua re-absorbed in moist air. Cinchonidine sulphate is sometimes contaminated with an ad- mixture of the corresponding salts of cinchonine and quinidine. To detect these, Hesse (Zeitsch. Anal. Chem., xv. 464) dissolves 0*5 gramme of the salt in 20 c.c. of water at 60° C, and adds 1*5 gramme of Rochelle salt. A crystalline precipitate of the sparingly soluble cinchonidine tartrate is produced. After standing one hour the liquid is filtered, and the filtrate tested with a drop of ammonia. Any turbidity or precipitate is due to the presence of more than 0*5 per cent, of cinchonine or 1"5 per cent, of quinidine. These may be distinguished by treating the filtrate with potassium iodide as described on pages 413 and 426. Hager recommends the use of 0*1 gramme of cinchonidine 1 Five commercial samples of cinchonidine sulphate examined by A. B. Prescott, lost, at 100° C, proportions of water ranging from 6 '36 to 7*04 per cent. B2H2SO4 + 3 aqua requires 7 '30 per cent. 430 HOMOCINCHONIDINE. sulphate, 0'3 of Kochelle salt, and 20 c.c. of cold water. The liquid is frequently agitated, filtered after one hour, and tested with a few drops of ammonia. As thus performed, tlie test is less strict than that of Hesse, but perhaps, on tlirit account, is better suited for medicinal purposes. The precipitate of cinchonidine tartrate obtained in the above tests is soluble in about 1200 parts of cold water, but almost wholly insoluble in a strong solution of Eochelle salt. After drying at 100° C, it contains 80*84 per cent, of cinchonidine. It will contain quinine if any of that base were present in the sample. In such case the solution of the precipitate in excess of dilute sulphuric acid will be notably fluorescent. Hesse has also proposed to distinguish the sulphates of the cinchona bases by their behaviour with chloroform. The an- hydrous neutral sulphates of quinine and cinchonidine are almost insoluble in alcohol-free chloroform, while the corresponding salts of cinchonine and quinidine dissolve readily (see pages 416, 427). Cinchonidine sulphate requires, when anhydrous, 300 of boiling or 1000 parts of cold chloroform, the undissolved portion becoming gelatinous. In the presence of cinchonine or quinidine sulphate its solubility in chloroform is increased. According to the British Pharmacopoeia (1885), cinchonidine sulphate (crystal- lised) is soluble in ether, a statement which is misleading, and correct only to a very limited degree. The U.S. Pharmacopoeia describes it " very sparingly soluble in ether or benzene." The presence of quinidine and quinine in cinchonidine sulphate can be recognised by the thalleioquin reaction and the fluorescence of the solution in dilute sulphuric acid. HoMociNCHONiDiNE, CigHggNgO (scc also page 392), accom- panies cinchonidine in many cinchona barks, especially that of C. rosulenta, and passes into the dark sulphate mother-liquors in the quinine manufacture. It crystallises from alcohol in anhydrous prisms, or from a dilute solution in leaflets, almost insoluble in water, but soluble in chloroform. B^HgSO^ + 6Efi crystallises from hot water in white needles, but from strong solutions the salt separates as a white mass, which after drying resembles magnesia. Hesse states that homocinchonidine is an essentially difl'erent substance from cinchonidine, and that it is not possible to convert one into the other. The two bases may be separated by fractional crystallisation of their sulphates from aqueous solution. In pre- sence of quinine sulphate, the homocinchonidine salt is said to crystallise in the form of cinchonidine sulphate. Hydrocinohonidine, CigHg^NgO, possibly identical with c i n- chonidine, occurs in the mother-liquors from homocinchonidine. CINCHONTNE. 4ai Cinchonine. C^gH^.N.O ; or C9H7N.C9Hi,(OH)N.CH3.i This important alkaloid is almost invariably present in cinchona harks. "When the free bases are crystallised from alcohol the cinchonine is deposited before the quinine ; unless the latter base is present in relatively large amount, in which case the greater part should be previously removed by crystallising the sulphates. Cinchonine crystallises from alcohol in anhydrous shining prisms or needles. It melts at 165° C. to a colourless liquid, and par- tially sublimes at a higher temperature. According to Hlasiwetz, it may be readily sublimed in a current of hydrogen or ammonia. Cinchonine is almost insoluble in cold water, and requires 2500 parts of boiling water for solution. One part of cinchonine dissolves in 120 parts by weight of cold rectified spirit or 28 of boiling alcohol, in 350 parts of chloro- form, in 371 of ether, and in 109 parts of amylic alcohol. It requires only about 13 parts of a mixture of 6 grammes of chloroform with 1 of rectified spirit, and is soluble in 23 parts of a mixture of 4 of chloroform and 1 of amylic alcohol. A. B. Prescott found the following to be the solubility of cinchonine in different physical conditions, and at the boiling-point of the solvent : — Condition of Alkaloid. Parts by Weight of Washed Solvent required. Ether. Chloroform. Amylic Alcohol. Benzene. CrystalUsed, . Amorphous, , "Nascent." 2. . 719 563 526 828 178 22 376 It will be seen from these results that amylic alcohol is by far the best solvent for cinchonine, except a mixture of amylic alcohol and chloroform. On the other hand, ether is the best solvent for effecting an approximate separation of cinchonine from quinine. When heated to a high temperature with an alkali, cinchonine yields q u i n o 1 i n e, CgH^N (page 1 1 5), together with other pro- ducts. With iodine trichloride, cinchonine yields a yellow pre- cipitate. 1 The constitution of cinchonine is discussed on page 168. * To obtain the alkaloid in the "nascent" state, the solvent was added to its sulphuric acid solution, which was then warmed to the boiling-point of the former. The liquid was next made slightly alkaline with ammonia, shaken, kept warm for five minutes, and filtered. 432 CINCHONINE SALTS. Cinchonine is not precipitated in the cold from a solution con- taining tartaric acid by adding sodium hydrogen carbonate. On heating the liquid, however, carbonic acid escapes and cinchonine is separated. The precipitate formed by ammonia in solutions of cinchonine is not soluble in excess of the reagent. The precipitate is amor- phous when first produced, but speedily becomes crystalline. Cinchonine is sharply distinguished from quinine by the very limited solubility of the free base in ether, by the solubility of the anhydrous neutral sulphate in chloroform, by its failure to give the thalleioquin reaction, by its dextro-rotatory power, and by the non-fluorescence of its solution in excess of dilute sulphuric acid. Methods of detection and separation based on these facts are given on pages 413 and 416. Cinchonine Sulphate, (Ci9H22N'20)2H2S04 + SHgO, forms short, hard, shining, clino-rhombic prisms, with dihedral summits. The salt becomes anhydrous at 100° C, and melts with partial decom- position at about 240° C. Cinchonine sulphate has a very bitter taste, dissolves in 54 parts of cold water, and is readily soluble (1:6) in alcohol. It is insoluble in ether or benzene. The anhydrous salt is soluble in 60 parts of cold or 22 of boiling chloroform, a fact which distinguishes it from the sulphates of cinchonidine and quinine. A solution of cinchonine sulphate does not give the thalleioquin reaction, and is not rendered fluorescent by dilution with very weak sulphuric acid. The mode of assaying of cinchonine sulphate is sufficiently in- dicated under the head of " Quinine Sulphate " (page 408 et seq.). Cinchonine Hydrochloride, G-i^qR^2^ ^0,^.01 + 211 fi, is readily soluble in water and alcohol, and somewhat so in ether and chloro- form. It has been not unfrequently employed to adulterate sulphate of quinine. In such case the solution of the sample in very dilute sulphuric or nitric acid will give a white, curdy pre- cipitate of silver chloride on adding silver nitrate. Cinchonine will be detected by the tests for that alkaloid. When heated in a dry test-tube, cinchonine hydrochloride gives purple fumes much resembling the vapour of iodine. The sulphates of the cinchona bases do not give this reaction, Hydrocinchonine, Ci9H24lSr20, is stated by H e s s e to occur in cuprea bark. CiNCHOTiNE, C19H24N2O (see page 392) is isomeric with cin- chonamine (page 438). It dissolves very sparingly in ether (1 :500). BHCl + 2 aqua requires about 48, and BgHgSO^-f 12 aqua about 35 parts of cold water for solution. QUINOIDINE. 433 CiNCHAMiDiNE is a basG probably isomeric with the above, and identical with hydrocinchonidine (page 430). Amorphous Cinchona Bases. Certain uncrystallisable alkaloids exist ready -formed in cinchona barks, the proportion present being probably affected by sunlight and the presence of any free acid in the bark. In the preparation of the salts of the alkaloids from cinchona bark, a further portion of the bases undergoes conversion into a resinoid substance known in commerce as " q u i n o i d i n e " or "amorphous quinin e." QuiNOfDiNB is obtained in quinine factories by precipitating the brown mother-liquors with ammonia, and consists largely of two alkaloids, quinicine and cinchonicine, which are isomeric with and appear to be due to the action of heat on quinine or quinidine, and cinchonine or cinchonidine, respectively. These amorphous products may also be obtained by heating the crystal- lised bases in glycerin to a temperature of 200° C, a red substance being formed at the same time. Commercial quinoidine is a dark brown, brittle, " extractif orm '^ mass, softening below 100° C, and having usually a slight alkaline reaction. It is a product of indefinite composition which has never been very favourably regarded in this country, though it has received official recognition in the German and United States Pharmacopoeias. Both works limit the ash to 0*7 per cent. By the latter it is described as almost insoluble in water, freely soluble in alcohol, chloroform, and dilute acids, and partly soluble in ether and benzene. When triturated with boiling water, the liquid, after filtration, should be clear and colourless, and should remain so after addition of an alkali. The German Pharmacopoeia requires that quinoidine should dissolve clear in an equal weight of 1 part of dilute acetic acid with 9 parts of water, so as to leave scarcely any residue ; and it must also form a clear solution with nine times its weight of cold dilute spirit. Quinoidine is said to be liable to adulteration with mineral matters, resins, liquorice, glucose, &c., all of which sophistications would be detected by one or other of the above tests. For the purification of quinoidine it is recommended to digest the commercial article on the water -bath, with 2 parts of benzene, while stirring or agitating. The clear solution is poured off, and the residue washed with more benzene. The benzene solution is then shaken with a slight excess of dilute hydrochloric acid, the acid liquid separated, and rendered faintly alkaline by caustic soda. A portion of this solution is then tested for purity VOL. III. PART II. 2 E 434 AMORPHOUS CINCHONA BASES. by dilution and addition of a few drops of a concentrated solution of sodium thiosulphate (hyposulphite), which ought not to produce any precipitate insoluble on a further addition of water. Should impurity be indicated, the whole of the solution of quinoidine hydrochloride must be treated with sodium thiosulphate as long as a permanent precipitate is produced. The liquid is then filtered, warmed, treated with excess of soda, and the precipitated quinoi- dine washed with water and dried at 100°. Thus purified, quinoidine appears in thin layers as a dark yellowish brown, transparent mass. It is completely soluble in benzene, alcohol and acids, and ether should dissolve at least 70 per cent, of it. The normal salts of quinoidine are said to have an alkaline reaction, and should be soluble in water in all propor- tions. When impure they form a clear solution in a little water, but the liquid becomes turbid on further dilution. To prepare a pure amorphous alkaloid, the acid sulphate of quinine or cinchonidine, according to the product required, is first rendered anhydrous by careful drying at 100° C, and is then raised for a few minutes to a temperature of 130° to 135° C, when it melts and is wholly converted into the acid sulphate of the new alkaloid. QuiNiciNE, C20H24N2O2, is a yellowish, amorphous, anhydrous "body, which melts at about 60° C, assuming a reddish-brown -colour which becomes darker at 100°. It is nearly insoluble in water, but has a bitter taste. The alcoholic solution has a strong alkaline reaction, and absorbs carbon dioxide from the air. The ■alkaloid is readily soluble in chloroform or ether. Quinicine gives 3. green coloration when treated in solution with chlorine- or bromine-water and ammonia, but is distinguished from quinine and quinidine by producing a white amorphous precipitate with sodium hypochlorite or solution of bleaching powder. In applying this test the liquid should be slightly, but not strongly, acidulated with hydrochloric acid. Quinicine may be separated from the accompanying alkaloids by adding ammonia, when the ammonium salt formed dissolves the liberated alkaloid, which may then be recovered by agitation with ether. If soda be employed instead of ammonia the alkaloid is thrown down as an oily mass. A solution of quinicine in excess of dilute sulphuric acid has a yellow colour but exhibits no fluorescence. Quinicine forms crystallisable compounds with acids, and double salts with the chlorides of platinum and gold. Neutral oxalate of quinicine dissolves readily in hot chloroform, alcohol, or water. In solution in a mixture of alcohol and chloroform the oxalate exhibits a right-handed rotation corresponding to a value of S„ = -I- 25-8° for the alkaloid. AMORPHOUS CINCHONA BASES. 435 Quinicine solutions are not precipitated by Rochelle salt. They are completely precipitated by adding excess of potassium thio- cyanate, which throws down quinicine thiocyanate as an oil which subsequently solidifies. It is soluble in pure water, but insoluble in solutions of alkaline thiocyanates. CiNCHONiciNE, C19H22N2O, when precipitated by soda from the solution of one of its salts, forms a yellow viscous mass readily drawn out into colourless strings. It liquefies at about 50° C, and at 80° turns brown. At higher temperatures {e.g., 100° C.) it becomes dark brown, and is converted into a substance resembling *' quinoidine." Upon cooling it remains soft. As deduced from the rotatory power of the oxalate, in alcoholic, aqueous, or chloro- formic solution, the value of So for cinchonicine is +20"1°. In most reactions, including its behaviour with ammoniacal salts and with hypochlorites, cinchonicine closely resembles quinicine, and hence is distinguished from cinchonine and cinchonidine. It is distinguished from quinicine by giving no green colour with chlorine- or bromine-water and ammonia. Cinchonicine is bitter, and in the free state has a strongly alkaline reaction. It neutralises acids perfectly, and many of the resultant salts are crystallisable. Anhydro-Bases. Certain amorphous bases, distinct from quini- cine and cinchonicine, exist ready-formed in cinchona barks. They are not convertible in quinicine or cinchonicine, and appear to be formed by the coalescence of two molecules of the crystallisable alkaloids, accompanied in the case of quinine and quinidine with the elimination of a molecule of water. Thus : — 2C^'ii^,^fi,-^^0 = C,„H^K,03. Quinine or Quinidine. Diquinicine. Cinchonidine or Dicinchonicine. Cinchonine. These bases constitute the greater part of the amorphous alkaloid contained in commercial quinoidine. They are wholly amorphous, as also are all their salts. The solution of diquinicine in excess of dilute sulphuric acid is fluorescent, gives the thalleioquin reaction, and is dextro-rotatory. Dicinchonicine does not possess these characters. De Vrij has pointed out a distinction between quinicine, cin- chonicine, and the natural amorphous alkaloids. If the neutral oxalates of the bases be rendered anhydrous by heating at 100° C, and the dry salts treated with chloroform, they behave in a characteristic manner. Oxalate of quinicine dissolves sparingly 436 REMIJIA ALKALOIDS. in chloroform at the ordinary temperature, but freely in the boiling liquid. On cooUng, the solution deposits the greater part oi the oxalate in crystals. Anhydrous oxalate of cinchonicine dissolves freely in cold chloroform. By adding a few drops of water on the surface, the solution is transformed in a few minutes into a solid mass. The oxalates of the natural amorphous alkaloids are very soluble in chloroform. The solution Temains clear on adding a few drops of water, but the water dissolves out some of the oxalate from its chloroformic solution. The amorphous oxalate is highly deliquescent, but the oxalates of quinicine and cinchoni- cine remain unchanged in the air. Alkaloids of Remijia Barks. The barks of the various species of Remijia vary greatly in the alkaloids which they contain. Thus, while the bark of R. peduncu- lata contains quinine and the allied alkaloid c u p r e i n e, that of R. Furdieana, which anatomically closely resembles the former, and has been confounded with it, contains no alkaloid closely related to quinine except comparatively small proportions (0"1 to 0*2 per cent.) of cinchonine and cinchonamine. Cusconi- d i n e, which occurs in the bark of R. Purdieana, is also found in that of Cinchona Pelletierana, together with cusconine and a r i c i n e, which two bases do not appear to be present in Remijia bark. The bases isolated from this bark by Hesse were (in addition to cinchonine and cinchonamine) concusconine, chair- amine, conchairamine, chairamidine and conchairamidine, the formulae and certain characters of which are given on page 393.^ ^ To extract the whole of the alkaloids, amounting to 2 to 3 per cent. , Hesse treated the finely-ground bark with hot alcohol, distilled off the solvent, treated the residue with excess of soda, and agitated with ether. On shaking the separated ethereal layer with dilute sulphuric acid, a pale yellow, curdy mass (A) separated, a portion of which remained suspended in the ether and part in the yellow acid liquid (B). On separating the latter (B) and adding very dilute nitric acid, cinchonamine nitrate was precipitated (mixed with the nitrates of some of the bases of group A), while cinchonine remained in solu- tion. The curdy precipitate (A) was digested with dilute soda, the liberated alkaloids washed and air-dried, dissolved in hot alcohol, and treated with one- eighth of their weight of sulphuric acid (H2SO4). Almost all the concusconine immediately precipitated as sulphate, a small additional quantity separating on cooling. Hydrochloride of chairamine was precipitated on adding strong hydro- chloric acid to the cold alcoholic mother-liquor. The filtrate from this was warmed and treated with a little potassium thiocyanate, and the precipitate of conchairamine thiocyanate filtered off. On adding more of the reagent, till the dark coloured solution became light brown, a pitchy mass separated, after the removal of which the solution was treated with excess of ammonia and shaken REMIJIA ALKALOIDS. 437 Concuscamidine does not appear to be a definite substance. All these alkaloids, like aricine and cusconine, contain four atoms of oxygen, and form a group only distantly related to cinchonine and cinchonamine. Concusconine has the same empirical formula as cusconine, aricine, and brucine, and resembles the strychnos alka- loids in some of its reactions. It crystallises with 1 aqua, and is dextro-rotatory, while cusconine has a lower melting-point, crystal- lises with 4 aqua, and rotates to the left. Concusconine resembles chairamine and its isomers in giving a deep green coloration when the solution in hydrochloric or sulphuric acid is mixed with con- centrated nitric acid, a reaction which is not common to cusconine or aricine. Echitamine or ditdine, an alkaloid contained in the bark of Alstonia scholaris,^ only differs by Hg from chairamine and its isomers, to which it presents a considerable resemblance. Alstonine, Cg^HgoNoO^, an amorphous alkaloid, which occurs together with alstonidine and par pliy vine in the bark of Alstonia constrida, is strongly fluorescent in acid solutions, and is not im- probably related to the cusconidine group. Hesse suggests that gelsemine^ Cg^HggNgO^, the poisonous alkaloid from the root of Od- semiuni sempervirens (yellow jesamine), is related to these alka- loids, and points out that the coloration it gives with nitric acid somewhat resembles the reaction of concusconine. with benzene. The benzene was extracted with acetic acid, and the acetic solution treated with a saturated solution of ammonium sulphate, which pre- cipitated a mixture of the sulphates of chairamidine and conchairamidine, separable by fractional crystallisation from hot water, in which the latter salt is the less soluble. ' Dita Bark, from Alstonia or Echites scholaris (Philippine Islands), has febrifuge properties, and contains the following alkaloids, together with several peculiar indifferent bodies. For the extraction and separation of the alkaloids the bark is extracted with hot alcohol, the solvent distilled off, the residue treated with ammonia and shaken with ether, which dissolves the ditamine. Tlie residue is treated with solid caustic potash and extracted with chloroform, which is evaporated, and the residue treated with concentrated hydrochloric acid, when ditalne hydrochloride separates while echitenine remains dis- solved. DiTAiNE, or Echitamine, C22H28N2O4 + 4 aqua, forms glassy prisms. Melts at 206°. Sd=--28-8°. Very bitter. Moderately soluble in water, alcohol, and ether. A strong base, not precipitated by ammonia. Decomposes sodium chloride, setting free caustic soda. Reduces Fehling's solution after boiling with hydrochloric acid. Concentrated sulphuric acid dissolves ditaine with purple-red colour ; nitric acid gives a purple-red, changing to green. Ditamine, CjgHjgNOg, an amorphous powder melting at 75°, soluble in alcohol, ether, and chloroform. Echitenine, C20H27NO4 ; brownish, amorphous, melting above 120°. Forms amorphous salts. 438 REMIJIA ALKALOIDS. A full description of the alkaloids of Remijia Purdieana and Cinchona Pelletierana barks has been published by 0. Hesse {Annalen, clxxxv. 296, 323; ccxxv. 211; Jour. Chem. Soc, xxxviii. 155 ; xlviii. 64 ; Pharm. Jour., [3], xv. 772). Ar i c i n e has been recently re-investigated by Moissan and Langrin (Compt. Rend., ex. 469). Cinchonamine and cupreine are described below. Cinchonamine, C19H24N2O (see page 393), occurs in the bark of Remijia Purdieana (false cuprea bark), a tree growing in the Columbian provinces of Antioquia. Its isolation is described on page 436. It is soluble in alcohol, ether, chloroform, benzene, and carbon disulphide, but only sparingly in water or petroleum spirit. It is very bitter, poisonous,^ yields no methyl chloride when heated with strong hydrochloric acid, gives no reaction with ferric chloride, and no colour with the thalleioquin test. It is said to be insoluble in strong hydrochloric acid, but dissolves in strong nitric acid with bright yellow, and in strong sulphuric acid with reddish-yellow colour. BgHgSO^ forms colourless prisms, readily soluble in cold water. BHXO3 forms short prisms melting at 195°, and very sparingly soluble in cold water (1 : 500). Cupreine, CigHggNgOg, or Ci9H2o(OH)N2.0H. This interest- ing alkaloid was discovered by Paul and Cownley in the bark of Cinchona cuprea or Remijia pedunculata, a tree growing in the districts surrounding the Magdalena River and the Upper Orinoco. Since 1881, cuprea bark has been largely used for the manu- facture of quinine.^ Cupreine crystallises from alcohol in the anhydrous form, but from ether in concentric prisms containing 2 aqua. When the alco- holic solution is diluted with water, the precipitate contains Bg-f aqua. The hydrates lose their water at 125°. Cupreine is only sparingly soluble in ether or chloroform, but readily in alcohol. The alcoholic solution is Isevo-rotatory (Sd= — 175'3°), alkaline, gives a dark reddish brown coloration with ferric chloride, and responds to the thalleioquin test. The solution of cupreine in dilute sul- phuric acid is not fluorescent. The free base precipitated by ^ S60 and Bockefontaine {Compt. Rend., c. 366) found cinchonamine (sulphate) six times as toxic as quinine, cinchonidine, or cinchonine. An injection of 0*25 gramme killed a guinea-pig in a few minutes. ^ For the preparation of cupreine, the crude quinine sulphate from the cuprea bark is dissolved in dilute sulphuric acid, excess of caustic soda added, and the quinine extracted by agitation with ether. The separated alkaline liquid is neutralised with sulphuric acid, when cupreine sulphate crystallises out. The sulphate is treated with ammonia and boiling ether, from which the cupreine crystallises on cooling. CUPREINE. 439 ammonia is only slightly soluble in excess, and may be extracted by ether. When cupreine is liberated from a salt by a fixed caustic alkali, it dissolves on adding an excess of the reagent, forming (with soda) a definite crystallisable compound containing CjgHgiNgO.ONa, from the solution of which the alkaloid cannot be extracted by ether.-'- This behaviour is due to the presence of a hydroxyl-group having a phenolic character (compare Morphine, page 311). The cupreinates of potassium and sodium are very soluble in water, and the corresponding compounds of calcium, lead, and silver have a strong alkaline reaction, and are more or less soluble in water. From the fact that alkalies form only mono-derivatives, while two atoms of the hydroxyl of cupreine can be replaced by acetyl,^ it is probable that the hydroxyl-atoms have difi'erent functions, as is the case with those of the morphine- molecule. When heated with hydrochloric acid (sp. gr. 1*125) to 140°, cupreine is converted into apoquinine, without formation of methyl chloride. The conversion of cupreine into quinine is described on page 398. Cupreine yields two classes of salts. Those of the general formula BA are sparingly soluble, and the aqueous solutions have a yellow colour, though their alcoholic solutions are perfectly colourless. The salts of the formula BA2 are, as a rule, pretty freely soluble, and their aqueous solutions are colourless. Cupreine Sulphate, B2H2SO4 + 6H2O, crystallises in minute white needles, very difficultly soluble in cold water, and insoluble in a saturated solution of sodium sulphate. BHgSO^ + HgO, crystallises in prisms sparingly soluble in cold water. Cupreine tartrate forms delicate efflorescent needles, very sparingly soluble in cold water. Cupreine thiocyanate is produced on adding potassium thiocyanate to a hot solution of the monohydrochloride. The liquid becomes turbid and gradually deposits acicular crystals of the salt. It is very sparingly soluble in, and is precipitated in an oily form by, an excess of the precipitant. HoMOQUiNiNB. When molecular proportions of quinine and ^ When cupreine and caustic potash or soda are mixed in molecular propor- tions, a portion of the alkaloid (10 to 20 per cent.) is extracted on agitation •with ether, but this may be prevented by using some excess of alkali. 2 DiACETYL-cuPREiNE, Ci9H2o(C2H30)2N202, was obtained by Hesse by heat- ing cupreine with acetic anhydride to 85° for a few hours. It forms hexa- gonal plates melting at 88°, and is soluble in alcohol, chloroform, and ether. The alcoholic solution is strongly alkaline, gives no colour with ferric chloride, but is turned dark green by chlorine and ammonia. By caustic alkalies, the base is hydrolysed in a few minutes with formation of cupreine and acetic acid 440 HOMOQUININE. cupreine are dissolved in dilute acid, and the solution precipitated by ammonia and shaken with ether, the solvent deposits on evapo- ration characteristic crystals ^ of a molecular compound of quinine and cupreine containing 0301124^202,0191122^202 + 4 aqua. The same substance is readily obtainable by precipitating a solution of sodium cupreinate with one of quinine hydrochloride : — C20H24N2O2, HCl + C19H21N2O. ONa = NaCl + C20H24N2O2, CjaH^iNaO. OH . This remarkable compound was discovered and described simul- taneously by Howard and Hodgkin {Jour. Ghem. Soc.,xli. 66), Paul and Oownley (Pharm. Jour., [3], xii. 497), and W. G. W h i f f e n under the name of homoquinine, prior to the isolation of cupreine by Paul and Oownley {Pharm. Jour., [3], XV. 221). It forms salts, having different characters from those either of quinine or cupreine, and is only resolved into its consti- tuents by precipitating the solution with excess of caustic soda, when the quinine may be shaken out with ether, while the cupreine remains in the alkaline liquid as sodium cupreinate. The analytical differences between homoquinine and cupreine have been fully described by Paul and Oownley {Pharm, Jour., [3], XV. 402). Cinchona Barks.^ The bark of various species of Cinchona, which, with about thirty other allied genera, constitute the tribe Cinchonece (order, RuMacece), have been long known for their antifebrile properties. These properties are chiefly due to peculiar alkaloids contained therein, which alkaloids are absent from all the allied genera, except certain species of Remijia. Nearly forty species of cinchona have been described, many of which can only be discriminated with great difficulty. The cin- chonas form a very intricate genus, one series running into another through a series of intermediate forms, the number of which is limited to some extent in their native country by the fact that particular species are practically confined to certain districts and elevations. Only some seven distinct species of cinchona yield bark of any practical importance. These are : — a. Pale or Crown Bark, yielded by Cinchona officinalis (Peru) and allied species. It occurs in quills, with a rough, blackish- brown or dark grey surface. (For analyses, see page 446 e^ seq.) ^ Homoquinine is deposited from ether in very thin prismatic laminae, hav- ing characteristically-shaped ends terminated with two oblique planes. 2 French ; Ecorces de Quinquina. German ; Chinxirinden. CINCHONA BARKS. 441 b. Yellow or Calisaya Bark is, with tlie exception of Ledger bark, the richest of all the cinchona barks. It now usually occurs in quills having a rough surface, but formerly was met with in flattened pieces known as " flat yellow bark." c. Red Bark, from C. rubra and G. succirubra^ is distinguished by the red colour of the sap and mature bark. It is extensively cultivated in India, and is remarkable for the large proportion of cinchonidine contained in it. (For analyses, see page 446 et seq. d. Pitayo Bark^ from (7. Pitayensis, is imported in short, brownish, curly pieces, rich in quinine and quinidine. e. Columbian and Carthagena Barks, from C. lucumifoUa and lancifoUa, are imported in soft quills or broken pieces of very variable quality. Quinine is often wholly absent {Year-Book Pharm., 1888, page 425). /. Ledger Bark, from Cinchona Ledger iana, is the richest in quinine of all cinchona barks. g. Cuprea Bark, yielded by Remijia peduneulata, is not a true cin- chona bark, and is the only known species of any other genus which yields quinine, though the allied alkaloid cinchonamine (page 438) has been found in R. Purdieana. Cuprea bark is peculiar in containing the interesting alkaloid cupreine^ (page 438). Hybrid barks are often produced, especially crosses between G. officinalis and C. succirubra (see page 447). A concise description of the chief kinds of cinchona bark, with their distinguishing characteristics, has been published by W. Elborne (Pharm. Jour., [3], xiv. 653). The British Pharmacopoeia of 1885 gives the following as the characters of official (red) cinchona bark, from Cinchona succirubra: — "In quills, or more or less incurved pieces coated with the periderm, and varying in length from usually a few inches to a foot or more — the bark itself from about one-tenth to a quarter of an inch thick, or rarely more ; outer surface more or less rough from longitudinal furrows and ridges, or transverse cracks, annular fissures, and warts, and brownish or reddish-brown in colour ; inner surface brick-red or deep reddish-brown, irregularly and coarsely striated; fracture nearly close in the smaller quills, but finely ^ Formerly, the cinchona trees were invariably cut down and the bark stripped oflF and dried in the sun or on hurdles over a fire. A greatly improved plan is to make longitudinal incisions in the bark of the growing tree, remove about half the bark, leaving the remainder intact, and cover the stem with moss. Fresh bark is then formed very rapidly, and this renewed bark not only contains a larger percentage of total alkaloids than the original, but the alkaloids contain a very much larger proportion of quinine. 442 COMPOSITION OF CINCHONA BARKS. fibrous in the larger ones ; powder brownish or reddish-brown ; no- marked odour; taste bitter and somewhat astringent. "^ The characters which conventionally determine the market- value of "druggists' quills" are often very fallacious, and have no- relation to the real quality of the bark. A silvery coating on the epidermis of the bark is one of the points to which a factitious importance is attached, and renewed bark, though richer in alkaloid than natural, does not sell readily for druggists' purposes owing to the absence of the above characters, though it is readily bought by quinine manufacturers. A specimen supposed to be one of cinchona bark can be readily identified as such by heating a small quantity in a test-tube, when a carmine-red or purple tar will be produced if the sample contain any of the cinchona alkaloids. Composition of Cinchona Barks. Cinchona barks contain, in addition to woody fibre, starch, gum, and mineral matters : — the characteristic alkaloids; quinovin, and c i n c h n a-r ed; cinchotannic and quinic acids; colouring-matters; wax, fat, and traces of volatile oil. Water extracts only a portion of the alkaloidal constituents of cinchona bark, and a hot infusion becomes turbid on cooling from the separation of sparingly soluble cinchotannates of the alkaloids. The solution obtained by treating cinchona bark with acidulated water gives a white precipitate with tannin, a whitish precipitate with caustic alkalies, and a yellow crystalline precipitate with platinic chloride. Either of these precipitates yields the charac- teristic odour of quinoline when subjected to dry distillation. The Ash of cinchona barks from South American sources was found by Carles to contain a sensible amount of copper, but this metal was not detected by D. Hooper in the bark from trees cultivated in India {Pharm. Jour., [3], xvii. 545), though in other respects the general results are in agreement. The average total ash from upwards of 300 specimens of Indian bark was found by Hooper to exceed 3 per cent. Renewed and old natural barks contain less, but the proportion never falls below 2 per cent. Young and branch barks give as much as 4 per cent, of ash, and ^ This description refers to red cinchona bark in quills, which, in the edition of 1886, replaces the flat red bark of South America, official in the Pharmaeoposia of 1867. The editors judiciously omit to name the place of origin, whether South America, Madras, or Ceylon; but they also omit to recognise red bark in shavings, although this is the form in which it is so most commonly met with in commerce, and notwithstanding that the shavings are often much superior, as regards the amount of quinine, to other forms. QUINOVIN. 443 the leaves from 5 to 6 per cent. From 24 to 27 per cent, of the ash is soluble in water, and an additional 67 to 70 per cent, in acid, leaving 5 to 6 per cent, of silica insoluble. QuiNOViN, or Chinovin, is an indifferent body which appears to be a constant constituent of the cinchonas, but in a proportion seldom exceeding 2 per cent. It is dissolved on treating the bark with weak soda, and on adding hydrochloric acid to the solution is precipitated in admixture with quinovic acid and cinchona-red. Treatment with milk of lime dissolves the quinovin and quinovic acid, which are reprecipitated by an acid and separated by treat- ment with chloroform, which dissolves the quinovin only.^ Quinovin has recently been re-investigated by Liebermann and Giesel {Berichte, xvi. 987; Pharm. Jour.^ [3], xvi. 987), who ascribe to it the formula ^^^^'f^w They believe two distinct modifications to exist, a-quinovin being present in cinchona bark and /S-quinovin in cuprea bark, a-quinovin is a white, very light, crystalline powder, quite insoluble in cold and almost insoluble in hot water, but soluble in cold caustic alkalies, lime and baryta water, and ammonia. It is difficultly soluble in chloroform, ether, and benzene. It dissolves in nearly absolute alcohol (43 : 100 at 15°), and is obtained on evaporation over sulphuric acid as a gummy mass without any tendency to crystallisation; but it separates on diluting the solution with water in rosettes of clear, very small needles. When precipi- tated by treating its solution in more dilute alcohol with water it is deposited in glittering white scales. The alcoholic solution of quinovin is dextro-rotatory (S=-f56'6), does not reduce Fehling's solution, and does not undergo fermentation with yeast. The powder is very bitter. In concentrated sulphuric acid it dissolves with orange-yellow colour and evolution of carbon mon- oxide. Its solution in glacial acetic acid is faintly blue, as is also the precipitate thrown down on diluting the solution with water. ^-quinovin closely resembles its isomer, but is not soluble in * Quinovin is prepared by Liebermann and Giesel from a bye-product obtained when the cinchona bases are extracted from bark by means of alcohol. On distiUing off the alcohol, and treating the extract with a dilute mineral acid, the alkaloids are dissolved as salts. The insoluble brown resinous matter is digested with warm milk of lime, and the filtered liquid precipitated by liydrochloric acid. The precipitate is dried and digested with alcohol, which leaves a little quinovic acid undissolved as a white powder. The brown solution is diluted with water till a precipitate commences to form, when small crystals of quinovin separate on standing. By recry stall isation from dilute alcohol it is obtained pure in the form of small glittering scales. 444 QUINOVIC ACID. absolute ether or ethyl acetate, and crystallises readily from dilute alcohol in handsome scales. In nearly absolute alcohol it dissolves freely with slight evolution of heat, but after a time, even if evaporation be prevented, the greater part separates in glassy crystals containing C^^liQ2p-^-^^ + 5C2iiQOj which effloresce very rapidly in the air with loss of the alcohol. The specific rotation of /5-quinovin is +27*9°. When boiled for some time with dilute sulphuric acid, or, preferably, when their concentrated alcoholic solutions are saturated with hydrochloric acid gas and allowed to stand in a closed vessel for thirty hours, both the quinovins undergo complete decom- position into quinovic acid and quinovit, a saccharoid body apparently containing CgH-^2^4- This substance is very hygro- scopic, and has not been ol^tained crystalline, but may be distilled unchanged in small quantities, has a sweet taste with a bitter after-taste, is dextro-rotatory, and does not reduce Fehling's solution even after boiling with acid. It is doubtful if quinovit has been obtained pure. Quinovic Acid, CggH^gOg, is constantly present in cinchona barks in small proportion, and forms a snow-white powder of tasteless needles or scales, quite insoluble in water, ether, or chloroform, and only very sparingly soluble in boiling alcohol or glacial acetic acid. It is best dissolved by adding ammonia to the alcohol, and may be reprecipitated by acetic acid. Quinovic acid decomposes carbonates, and is soluble in ammonia and solutions of the caustic alkalies and alkaline earths, the solutions frothing like soap. The ammonium and calcium salts crystallise from alcohol in needles ; the former salt losing its ammonia by exposure to air, or on boiling its solution. On adding an acid to an alkaline solution of quinovic acid, a hydrate of quinovic acid is thrown down as a very voluminous jelly, the whole contents of the vessel solidifying. In this form quinovic acid is very soluble in ether and alcohol. From the solution, the insoluble form of the acid separates in needles on standing. Quinovic acid gives with cupric sulphate first a green colour and then a precipitate, and the latter, when washed, has a bitter metallic taste. When heated to about 300° C, quinovic acid yields pyroquinovic acid, carbon dioxide, and secondary products. CiNCHOTANNiN or CiNCHOTANNic AciD, Ci^HjgOg, is a glucosidc which is an important constituent of cinchona barks, in which it exists in the proportion of 3 to 4 per cent. It may be precipitated IS a lead salt from a decoction of bark — previously treated with magnesia to separate colouring-matter — by addition of lead acetate. The yellow precipitate when decomposed by sulphuretted hydrogen CINCHONA BARKS. 445 yields a solution of cinchotannic acid. It is a yellow, amorphous, very hygroscopic substance, very soluble in water, alcohol, and ether ; gives a green colour with ferric chloride ; is precipitated by starch, albumin, gelatin, and tartar-emetic; is hydrolysed by dilute acids into glucose and c i n c h o n a-r e d ; gives p r o t o- catechuic and acetic acids on fusion with caustic potash ; yields pyrocatechol on dry distillation ; and is readily decomposed in presence of excess of alkalies, with formation of cinchona-red. The cinchotannates of the alkaloids existing naturally in cinchona bark are difficultly soluble in water, but dissolve readily in acidulated water — probably with decomposition. Cinchona-red or Cinchofulvic Acid, C12H14O7. This is the natural colouring-matter of (red) cinchona barks, from which it may be extracted by treatment with alkalies. It is re-precipi- tated from its red ammoniacal solution on addition of hydrochloric acid. The solution also yields a red precipitate with barium chloride. Cinchona-red is also produced by boiling cinchotannic acid with dilute sulphuric acid, glucose being simultaneously formed. On fusing cinchona-red with potash, protocatechuie acid, Ci^HgO^, is produced. Cinchona-red is insoluble in water or ether, but sparingly soluble in alcohol. It is sometimes present in red bark to the extent of 10 per cent. QuiNic Acid or Kinic Acid, CyH^gOg, crystallises in well- defined hexagonal plates, fusing at 161° C. It has a strong and purely acid taste, and is soluble in 2 parts of water, less soluble in alcohol, and almost insoluble in ether. Its solutions are Isevo- rotatory. When distilled with manganese dioxide and sulphuric acid, kinic acid yields quinone, C^^H^Og, which is deposited in deep yellow prisms on the cooler part of the apparatus. This reaction was proposed by Stenhouse as a test for true cinchona hark. The Alkaloids are the most important constituents of cinchona barks, in which they exist in the form of cinchotannates and quinates. The principal of them have already been fully described (page 398 et seq.). The official tincture and liquid extract of cinchona contain only a portion of the alkaloids of the bark used for their preparation {Pharm. Jour., [3], xiv. 445, 797 ; xv. 453, 480). Some kinds of cinchona bark are occasionally wholly destitute of alkaloids. Such specimens do not give a carmine-red tar when heated in a dry tube, this reaction being produced only when a cinchona base is heated with woody fibre. The proportions of total alkaloids, as also the percentage of quinine, are extremely variable (see Pharm. Jour., [3], xiv. 444, 445, 458, 797, 810; xv. 411, 453, 480), and chemical analysis 446 COMPOSITION OF CINCHONA BARKS. is the only means of forming an opinion as to the richness of a specimen of bark. De Yrij found the G. officinalis grown at Ootacamund to contain a proportion of total alkaloids varying from 11-96 per cent, (of which 9'1 per cent, was quinine) down to less than 1 per cent. Quinine is not seldom absent from barks con- taining certain other of the cinchona alkaloids. The highest yield of total alkaloid known is about 15 per cent. An Ootacamund bark has been found to contain 13 J per cent., the greater part being quinine. In eighty specimens of Calisaya Ledgeriana, from Java, Moens in 1879 found from 12*50 to 1*09 per cent, of total alkaloids, the quinine ranging from 11*6 to 0'8 percent. Of late years, owing to improved methods of cultivation, the proportion of quinine has sensibly increased. In the same species of cinchona, the natural bark, mossed bark, and renewed bark con- tain very different percentages of quinine, the last being the richest ; besides which the external conditions under which the trees are grown largely affect the relative and absolute proportions of the alkaloids in the bark. Quinine and cinchonine are the cinchona alkaloids of the most frequent occurrence. Cinchonidine is hardly less common, and it occurs very largely in Indian red bark. Quinidine is not very frequent, and is never present in large amount. The following are analyses by D. Howard of bark from cultivated cinchona trees grown near Bagota, United States of Columbia (New Granada). The characters of the barks have been described by E. M. Holmes {Phai-m. Jour., [3], xxii. 875). Species of Cinchona. 6 '3 h 1 6 a 1 f§ li ^ S^ 1 a g o H:3 < Tliomsoniana, 5-94 4-45 0-27 0-26 0-82 0-74 6-54 Ledgeriana verde, 5-90 3-68 0-00 0-20 0-01 0-44 4-33 Morada, '.'.'.'. 7-30 5-48 0-00 trace 0-10 0-78 6-26 306 2-30 000 0-50 0-04 0-38 3-22 Tuna, 904 6-78 40 018 0-38 0-42 8-16 Pombiana, 6-88 4-41 0-34 trace 0-02 0-26 5-03 Officinalis, 6-32 4-74 1-23 0-07 0-10 0-42 6-66 Succirubra ,' . 5-93 4-45 2-77 0-02 0-12 0-36 7-72 Hybrid, . 3-32 2-49 1-92 trace 0-04 0-52 4-97 This is by no means a typical analysis of succirubra bark (see footnote, page 447). The following are analyses by D. Hooper, Government Quinologist, of cinchona barks grown in the Madras Govern- ment plantations, and shown at the Indo-Colonial Exhibition in 1886:— ALKALOIDS OF CINCHONA BAKKS. 4.47 Source of Bark. •It 6 a "a I i 1 <6 a a o ll 1^ Species. Description. C. succirubra, . Natural 2-57 1-91 1-14 ... 2-11 0-88 6-04 i» Mossed 2-27 1-69 1-68 ... 2-03 0-98 6-34 >t Renewed 2-47 1-84 1-25 ... 1-48 0-71 5-28 »» • • Branch 1-85 1-38 1-59 2-28 1-16 6-41 Root 1-66 1-24 1-43 0-41 0-77 1-27 5 12 >> Renewed (shavings) 3-09 2-30 2-06 1-16 1-45 6-97 C. robusta,^ Natural 1-92 1-43 1-58 ... 2-08 0-31 5-40 »i • Mossed 2-58 1-92 0-77 3-16 0-35 6-20 »> Renewed 5-92 4-40 0-51 ... 2-54 1-65 910 M Branch 2-20 1-64 1-17 2-71 0-50 602 C. micrantha, . Natural ... 1-92 0-40 2-32 >• Renewed trace trace 1-12 ... 2-45 1-02 4-54 >> Branch 1-60 0-45 2-05 C. Calisaya, . Natural 1-62 1-21 2 13 ... 2-32 0-29 5-95 „ Branch 0-79 0-59 1-93 073 0-48 3-73 C. Angliea,^ . . Natural 1-09 0-81 1-49 0-29 0-88 0-44 3-91 «> • Branch trace trace 2-04 0-25 ... 0-36 2-65 C. Ledgeriana, Natural 7-38 5-49 0-82 ... 1-33 0-88 8-52 » Branch 2-97 2-21 107 0-49 0-50 4-27 C. Javaniea, . Natural ... 2-64 1-32 ... 0-48 4-44 „ Branch ... 1-49 1-43 ... 0-45 3-37 C. offieinalis, . Natural 3-72 2-77 0-39 0-16 1-57 0-50 5-39 » Mossed 4-57 3-40 0-45 0-20 1-50 0-62 617 ,, . , Renewed 5-66 4-21 0-65 0-22 0-85 0-70 6-63 C. paludiana, . Natural 0-05 0-04 0-39 ... 10 0-43 0-96 »> Renewed 0-68 0-51 0-28 ... 1-19 0-87 2-85 C. Pitayensis, . . Natural 3 14 2-34 1-93 1-10 0-56 0-39 6-32 If Mossed 5-12 3-81 1-91 0-63 0-95 0-37 7-67 „ Renewed 3-36 2-50 2-33 0-78 0-52 0-55 6-68 C. Humbolticma, . Natural 3-01 2-24 0-49 trace 1-55 0-90 5-18 »» Renewed 1-72 1-28 0-43 0-64 107 3-42 » CiTichona robusta is a hybrid or cross between C. sticcirubra and C. officinalis, and C. Anglica between C. succirubra and C. Calisaya (W. T. Thiselton Dyer, Pharm. Jour., [3], XV. 481). Analyses of a number of cinchona barks from Madras have been published by B. H. Paul {Pharm. Jour., [3], xiv. QQQ). D. Hooper (Year-Book Pharm., 1888, page 430) gives the following as the percentage proportions of alkaloids in typical barks from trees grown on the plantations of the Madras Govern- ment : ^ — ^ In commenting on these results, B. H. Paul strongly deprecated the preference given to the red bark over that of the crown and Calisaya barks, 448 COMPOSITION OF CINCHONA BARKS. Bark from C. succirubra.^ Crown Bark from C. officinalis.^ Hybrid Barks. Quinine Cinchonidine, Quinidine, Cinchonine, Amorphous alkaloids, . 1-40 2-25 1-92 0-68 2-98 1-40 0-08 0-42 0-42 2-16 1-82 04 117 0-56 Total, 6-25 5-25 5-75 Hooper gives the following as the average centesimal com- position of the alkaloids from numerous species of the above barks : ^ — Red Barks.2 Crown Barks. Hybrid Barks. Quinine, Cinchonidine, Quinidine, .... Cinchonine, . Amorphous alkaloids, . 22-2 361 30-9 10-8 55-9 26-7 1-5 8-0 7-9 41-2 40-9 0-5 9-7 7-7 Total, 100-0 100-0 100-0 which had acted prejudicially on all concerned. This prejudice had extended to the B. Pharmacopoeia, with the result that "every bark preparation that appeared there was, in fact, an officially adulterated article," and contained for every unit of quinine, the only really valuable constituent, 2, 3, or 4 per cent, of the comparatively valueless ones ( Year-Book Pharrti., 1888, page 440). The typical crown bark, of which the analysis is given in the text, Paul regarded as of only inferior quality, the proportion of alkaloids yielded by crown bark of any value being from 3 to 5 per cent, of sulphate of quinine, and something less than 1 per cent, of cinchonidine. In the red bark these proportions were reversed, the quinine being usually 1^ per cent., with 3, 4, and 5 per cent, of cinchonidine. Red bark had become a drug in the market, and almost worthless as a source of quinine. In replying to these criticisms {Pharm. Jour., [3], xix. 504), Hooper pointed out that the fifty crown barks of which the analyses were given were undoubtedly of a typical character ; barks of the richer species, as angustifoUa, were purposely omitted ; and that mossed and renewed barks are also eliminated. ^ See foregoing footnote. ^ The mixed total alkaloids of red bark have been introduced into commerce under the name of " Q u i n e t u m. " This preparation is completely soluble in warm, strong alcohol ; 3'1 grammes dissolved in 10 c.c. of normal hydrochloric CINCHONA BARKS. 449 Assay of Cinchona Barks. The complete assay of the various species of cinchona bark, with the view of ascertaining the proportion of the different alkaloids contained in them, is a process at once important and difficult. A great many methods have been proposed, but very few can be trusted to yield accurate results when employed by chemists unused to them. Again, a process which is suitable when quinine is the chief alkaloid present becomes difficult of application when the cinchonidine is in excess. Unfortunately, also, certain processes which are extensively employed by professed quinologists are kept strictly secret. In choosing a process of assaying cinchona bark, due considera- tion should be given to the kind of information required. Thus, a pharmacist desiring to know the alkaloidal strength of his bark will require a less accurate and elaborate process than a manufacturer buying bark for the extraction of quinine. Again, in some cases it is sufficient to determine the percentage of total alkaloids, while in others it is very important to ascertain the proportion of crystal- lised sulphate of quinine which the bark is capable of yielding. On this account, it is desirable to discuss the determination of the total alkaloids and of the actual quinine separately. a. The British Pharmacopoeia of 1885 prescribes the following standard of quality and method of assaying ^ red cinchona bark : — " Test. — When used for purposes other than that of obtaining the alkaloids or their salts, it should yield between 5 and 6 per cent, of total alkaloids, of which not less than half shall consist of quinine and cinchonidine,^ as estimated by the following methods : — "1. For Quinine and Cinchonidine. — Mix 200 grains of red cinchona bark, in No. 60 powder, with 60 grains of hydrate of acid should give a clear solution, which, on addition of 2 grammes of Rochelle salt must yield a precipitate equal in weight, after drying, to at least 65 per cent, of the quinetum taken. — (From the Unofficial Formulary of the Dutch Society for the Advancement of Pharmacy, Pharm. Jour., [3], xii. 662.) " Quinetum sulphate " occurs in commerce in a perfectly crystallised form. ^ Based on a method devised by E. R. Squibb {Ephemeris, i. 106). 2 This is not a veiy exacting requirement. Unfortunately no indication is given of the proportion of actual quinine which should be present. Con- sequently, one bark may have double the intrinsic value of another, and yet both be fairly up to the B.P. standard. It is quite possible for a bark to contain the required proportion of total alkaloid, of which one-half shall consist of cinchonidine and quinine, but still only traces of the last alkaloid to be present. As the shavings are excluded, and the established prejudice as to the appearance of quills tends to favour the use of natural rather than the richer renewed bark, the general effect is to promote the use of the least VOL. III. PART II. 2 F 450 B.P. METHOD OF ASSAYING CINCHONAS. calcmm; slightly moisten the powders with half an ounce of water ; mix the whole intimately in a small porcelain dish or mortar ; allow the mixture to stand for an hour or two, when it will present the characters of a moist, dark brown powder, in which there should be no lumps or visible white particles. Transfer this powder to a six-ounce flask, add three fluid ounces of benzolated amylic alcohol,^ boil them together for about half an hour, decant and drain off" the liquid on to a Alter, leaving the powder in the flask ; add more of the benzolated amylic alcohol to the powder, and boil and decant as before ; repeat this operation a third time ; then turn the contents of the flask on to the filter, and wash by percolation with more of the benzolated amylic alcohol until the bark is exhausted. If, during the boiling, a funnel be placed in the mouth of the flask, and another flask filled with cold water be placed in the funnel, this will form a convenient condenser which will prevent the loss of more than a small quantity of the boiling liquid. Introduce the collected filtrate, while still warm, into a stoppered glass separator , add to it 20 minims of diluted hydrochloric acid, mixed with 2 fluid drachms of water; shake them well together, and when the acid liquid has separated this may be drawn off", and the process repeated with distilled water slightly acidulated with hydrochloric acid, until the whole of the alkaloids have been removed. The acid liquid thus obtained will contain the alkaloids as hydrochlorates, with excess of hydro- chloric acid. It is to be carefully and exactly neutralised with am- monia while warm, and then concentrated to the bulk of 3 fluid drachms. If now about 15 grains of tartarated soda, dissolved in twice its weight of water, be added to the neutral hydro- chlorates, and the mixture stirred with a glass rod, insoluble tartrates of quinine and cinchonidine will separate completely in about an hour ; and these collected on a filter, washed, and dried, will contain eight-tenths of their weight of the alkaloids, quinine and cinchoni- dine, which, divided by 2, represents the percentage of those alka- loids. The other alkaloids will be left in the mother-liquor." "2. For Total Alkaloids. — To the mother-liquor from the pre- ceding process add solution of ammonia in slight excess. Collect, wash, and dry the precipitate,^ which will contain the other alkaloids. The weight of this precipitate, divided by 2 and valuable kinds of bark for pliarniaceutical purposes. In the present Pharma- copoeia definition, the quinine standard of cinchona bark is reduced much below that of the 1867 edition, and only corresponds to a content of about 1 per cent, of quinine. 1 Prepared by mixing 3 volumes of benzene with 1 of amj'lic alcohol. ■■^ It would be better to extract the alkaloids with chloroform. ASSAY OF CINCHONA BARKS. 451 added to the percentage weight of the quinine and cinchonidine, gives the percentage of total alkaloids." h. The following method of determining the total alkaloids of cinchona bark is that of J. E. D e Y r i j, with certain modifications suggested by A. B. P r e s c o 1 1 and J. M u t e r. It is [)ractically the official process of the United States Pharmacopoeia, and is applicable to all varieties of bark. Twenty grammes of the finely- powdered bark, weighed after drying at 100° C, is thoroughly mixed with 5 grammes of quick-lime and 50 c.c. of water. The mixture is then dried at a very gentle heat, not above 70° to 80° C. When dry, it is transferred to a flask fitted with an inverted condenser, and boiled with 200 c.c. of the strongest rectified spirit.^ The liquid is allowed to cool, and is then passed through a filter six inches in diameter, and the residue is again boiled with 100 c.c. of alcohol, and then washed twice with alcohol, using 50 c.c. each time. The filtrate is next rendered slightly acid by dilute sulphuric acid, and, after allowing any precipitate of calcium sulphate to subside, the liquid is passed through a very small filter, which is washed with a little alcohol. The filtrate is evaporated or distilled till the alcohol is expelled, cooled, and again passed through a small filter, the precipitate, consisting of quinovic acid and fatty matter, being washed with water slightly acidulated with sulphuric acid. The filtrate, which contains the alkaloids in the form of acid sulphates, is then con- centrated to about 50 c.c. or less, and transferred to a separator of 100 to 150 C.C. capacity. Soda is next added in decided excess, and the liquid containing the separated alkaloids then shaken without delay with 30 to 40 c.c. of previously washed chloroform. After a few minutes' agitation, the liquid is left at rest till the chloroform has completely separated from the aqueous layer. The lower stratum is .then tapped off", and the watery liquid agitated three times more with chloroform, using from 25 to 30 c.c. on each occasion. The mixed chloroformic solu- tions are then distilled to a small bulk, the residual liquid evaporated to dryness, and the residue dried in the water-oven till constant in weight. The amount so found represents the total alkaloids in the 20 grammes of the bark taken. Cinchonine and cinchonidine readily become anhydrous at 100°, and quinine may be trusted to do the same. Quinidine retains 2 aqua in the water-oven, but the proportion in which this base occurs is too ^ The spirit may be methylated, but should be previously dehydrated to about 93 per cent, by being kept in contact with freshly-ignited potassium carbonate. A Soxhlet's tube or equivalent arrangement might probably be advantageously employed for the alcoholic treatment described in the text. 452 ASSAY OF CINCHONA BARKS. small to affect appreciably the accuracy of the assumption that the alkaloids are weighed in the anhydrous state. If preferred, however, the temperature may be raised to 115° C.^ For the assay of yellow cinchona bark, ether may be substituted for the chloroform employed in the above process. c. The following method of assay is due to P r o 1 1 i u s {Arcliiv d. Pharm., ccix. 85, 572), with precautions suggested by D e Yr ij, B i e 1, and others. It is practically the process of the German Pharmacopoeia (1882): — Prepare a mixture of 85 parts of ether (sp. gr. 0-724 to 0*728), 10 parts of alcohol (sp. gr. 0-830 to 0-834), and 5 parts of ammonia (sp. gr. 0-960), aU hy weighty making 100 parts in all. Treat 10 or 20 grammes (according to its supposed richness) of the previously dried and very finely- powdered cinchona bark in a tared glass-stoppered bottle with twenty times its weight of the above solvent-mixture, observe the exact weight of the bottle and its contents, and agitate at intervals during four hours. If any loss of weight occurs, add sufficient of the solvent-mixture to restore it, agitate and weigh again. Care- fully decant into a flask as much of the solution as can be poured off perfectly clear, and ascertain the quantity taken by re-weighing the stoppered bottle. Distil off the ether, evaporate the residual liquid in a tared beaker at 100°, and weigh the residue when thoroughly dry. Then : — Weight of solvent-mixture employed x weight of residue _ T total crude alkaloids Weight of alkaloidal solution decanted ~ I *" bark taken. The crude alkaloids thus obtained are dissolved in dilute hydrochloric acid, the solution filtered, and the filtrate made alkaline with caustic soda and repeatedly agitated with chloroform, which is separated, evaporated, and the residual alkaloids weighed after drying at 100° in the usual way. De Vrij found the purified alkaloids so obtained from a red Java bark to be 83-5 per cent, of the total crude alkaloids previously extracted. ^ With a few modifications of minor importance, the method described in the text is that used by most quinologists. One well-known authority prefers to work on a very large quantity of the bark (about 2 lbs.). Having treated with lime, alcohol, and acid in the manner described in the test, he pre- cipitates the aqueous solution of the sulphates with soda, filters, washes slightly, dissolves the precipitate in acetic acid, and filters from any undis- solved colouring-matter. The filtrate is divided into two equal parts, A and B. A is precipitated by ammonia, filtered, and the filtrate shaken Avith chloroform, which is then used to dissolve off the alkaloids from the filter. The solution is evaporated, and the total alkaloids weighed, after drying at 115" C. B is treated in a manner similar to A, but the chloroform is replaced by ether. The alkaloid thus dissolved is called "quinine," the difference between that and the total alkaloids being the "other alkaloids." PRECIPITATION AS PICRATES. 453 d. The following method for the estimation of the total alkaloids of cinchona bark is that of H a g e r. The accuracy of the method has been confirmed by 0. Me din {Zeit. Anal. Chem., viii. 477 ; ix. 447) : — Ten grammes of the dried and finely-powdered bark are treated for a short time with 100 c.c. of water and 10 grammes of caustic potash solution of 1*35 specific gravity. The mixture is then heated and kept at the boiling-point for a quarter of an hour. Fifteen grammes' weight of diluted sulphuric acid (sp. gr. 1*11 5) is next added, and the whole boiled for twenty minutes. After cooling, both liquid and residue are transferred to a measuring cylinder, and diluted with water till the whole has a volume of 110 c.c.^ The liquid is then passed through a dry filter, and 60 c.c. of the filtrate (=6 grammes of bark), mixed with 50 c.c. of a cold, saturated, aqueous solution of picric acid. After standing for half an hour the precipitated picrates are filtered off, washed with a little cold water, dried at 100°, and weighed. The product contains 42*5 per cent, of its weight of alkaloids, calculated as quinine. A preferable plan is to suspend the washed precipitate in cold water, add excess of caustic soda, and agitate with chloroform. The chloroformic solution of the alkaloids is then treated as in process b. The picric acid method of assaying cinchona barks is said to be accurate, easy, and ex- peditious. Separation of CincTiona Bases. The separation of the alkaloids of cinchona and allied barks is an extremely complex operation, and as respects the rarer alkaloids outside the scope of this work. But the accurate separation even of the commoner alkaloids, such as is frequently required for com- mercial purposes, is very difficult, and its accurate performance presents special obstacles to an inexperienced analyst. In some cases it is sufficient to determine the proportion of crystallisable quinine, which may be effected as described below, but in other cases it is necessary to determine also the cinchonine, cinchonidine, and occasionally the quinidine, quinamine, and amorphous alkaloids. For the separation of quinine from the admixed alkaloids, ether is usually employed, but it must be remembered that the separation effected by this solvent is not an absolute one, all the free cinchona bases being more or less soluble in ether, especially in the presence of quinine. The anhydrous sulphates of quinine and cinchonidine are almost insoluble in chloroform free from alcohol (see page 430), but in presence of sulphate of cinchonine or quinidine sensible ^ This is allowing 100 c.c. for the liquid, and 10 c.c. for the bulk of the residual woody fibre, &c. 454 SEPARATION OF CINCHONA BASES. quantities pass into solution. Crystallisation of the quinine sulphate from water afi'ords a simple and fairly accurate mode of separation, which has the advantage of being similar to the pro- cess employed by the manufacturer, and hence is regarded by many as furnishing the best proof of the yield likely to be obtained in practice. The following method of separating the quinine in the form of sulphate is described by J. Muter {Analyst^ v. 223) : — Treat the total alkaloids, or the ether-residue from 20 grammes of bark, with warm distilled water slightly acidulated with dilute sulphuric acid, till the mixture is perceptibly acid. Add water to make 70 c.c. for each 1 gramme of alkaloids taken, and then very dilute soda with constant stirring till the liquid is exactly neutral, with a faint tendency to acidity. Digest the liquid at 85° C. for five ininutes ; then cool, and leave at 15° C. for one hour. Filter the liquid through a small double filter (2| inches diameter), the two filters being previously trimmed to equal weight, and receive the filtrate in a graduated cylinder. Wash carefully with water at 15° C. till the filtrate and washings measure 90 c.c. for each 1 gramme of the mixed alkaloids. The filter and contents are now completely dried at 100° C, and weighed, the second filter being used as a counterpoise. To the weight in grammes add •000817 gramme for each c.c. of filtrate and washings. The sum divided by 0*855 gives the corresponding amount of crystallised sulphate, and this number multiplied by 5 gives the crystallised quinine sulphate obtainable from 100 grammes of dried bark. The quinine sul])hate so obtained is apt to contain cinchonidine sulphate, and should be tested for this admixture as directed on page 412. The remaining alkaloids may be recovered from the mother-liquors by concentrating the liquid somewhat, adding soda in excess, and agitating with chloroform. On evaporatmg the chloroform, the bases will be obtained in a solid state, and may be separated as described on page 459. The following scheme for the separation of the principal cinchona bases is founded on a method described by D e Vrij (Pharm. Jour., [3], ii. 642). The process requires a considerable weight of alkaloids, and does not yield strictly accurate results. Traces of quinidine and cinchonidine are dissolved by the ether, and are only recovered on treatment of the amorphous alkaloids with a limited quantity of ether as directed.^ In presence of much quinine the solubility of cinchonidine in ether is notably increased. 1 The solubility of the cinchona bases in ether at 15° C. is given by A. B. Prescott as being :— for quinine, 1 : 25 ; quinidine, 1 : 30 ; cinchonidine, 1 : 188 ; and for cinchonine, 1 : 371. The amorphous cinchona alkaloids are readily soluble in ether. DE VRIJ'S METHOD OF SEPARATION. 455 43 00 2 ^ S^ i.2 04^ n ■**"« OS ■« .5 'S "SO ^ o p S 3*:" S^'SSS2l_.2 ^"^ "o -o '"' ^ c ]g< ,5 ? CS OS .^ 2 r! o w kS.2-^^ oj O) S Q, O « r; 2 S * C3 CS i S^ .°5 is 3-^.2 c4 ^ —, BO q a 3 0) S o 2; IS .15 w -*J 3 2 O o Ot:; a S > m ^ P 3.2 «-^ •2-2 J?. 2-2 b e ^. b5 == 3 3 St; 2-1 III M Its::: S ?: o ^ 5 2 o ° ^ 3 5 0( o o ^^1 « a> c8 o aj CO ,3 m-H cj m .«> 2 =* 3 -ta o "P 2.2"'bb §3-3 38^ Ot^ „^ >>5 a' S 3 Hm a <»s •2 '5 1 ■*^ S 3 J- "K m • CO fl aj • •, (u 5|i!illi -r3 = 3-§«^.-ga'|^g^ S H 13 p,^<-ti^ a ^ .V,x: c- s. JO'S 1 .2 2 « 0- '-§25*3 g2 ft>» «S^Sa-S £ ^a a X .2 C3 5S5gg&£si 73 C> .2^,2 ^ 3 =s*^ a « s 2 -2 ^ o «Sa3>ft*":S OtD^^.ii' £3 "-^ -»J S • . -rt (1? X3 « OS ,4 mm SCO, « o Ol c S3-; 3, - -.""^ C.2 c5"5^'5b--3o2 «i ^ .;-• ^ > ^ M< „ 'Otias^"^* "^m " O a> S -S a 5* o to S o 2 " S o g* a.2?§^'-§is:2 OS'S 2 2 =« S « ^ =3=2 3 a2'-' » -afeoicg^^^sjsS o-j3°o3^-»;^a 456 PRECIPITATION AS lODOSULPHATE. The precipitation of the quinine as herepathite is stated by David Howard to give accurate results in skilful hands ; but, instead of throwing down the quinine from a sulphuric acid solu- tion by tincture of iodine, De Yrij recommends, in his more recent papers, the use as a precipitant of the iodosulphate of the amorphous cinchona bases commercially known as " quinoidine." This forms a readily soluble iodosulphate, and by employing a previously prepared solution of it any error from the formation of periodised iodosulphate of quinine is avoided.^ De Vrij directs ^ Pharm. Jour. , [3], vi. 461 ; xii. 601 . One part of commercial ' ' quinoi- dine" is heated on a water-bath with 2 parts of benzene, whereby the quinoidine is partly dissolved. The cold, clear benzene-solution is shaken with excess of dilute sulphuric acid, an aqueous solution of the acid sulphate of quinoidine being thus obtained. The amount of alkaloid is then determined in a small portion of this solution, and the rest is slowly treated with 1 part of iodine and 2 of potassium iodide dissolved in water for every 2 parts of amorphous alkaloid known to be present. The iodine solution must be added very gradually, with vigorous stirring, so that no part of the quinoidine solution shall come in contact with excess of iodine. A fiocculent, orange- coloured precipitate of iodosulphate of quinoidine is formed, which by slight elevation of temperature coagulates to a dark brownish-red resinoid body. The yellowish liquid is poured off, and the precipitate heated to 100° with water, when the liquid is poured away. The adhering moisture is evaporated off at 100° C, when the iodosulphate remains as a soft and tenacious mass, which becomes brittle on cooling. One part of this substance is dissolved by heating with 6 |)arts of alcohol of 92 to 95 per cent. The solution is allowed to cool, filtered, evaporated to dryness, and the residue dissolved in 5 parts of cold alcohol. When filtered, the solution thus obtained is ready for use. In using this solution for the determination of crystallisable quinine in a mixture of cinchona bases (as free as possible from cinchonidine), 1 part by weight of the alkaloid is dissolved in 20 parts of alcohol of 92 to 95 per cent., containing 1*5 per cent, of sulphuric acid (H2SO4), which amount is sufficient to convert the bases into acid sulphates. The solution is then diluted with 50 parts of unacidulated alcohol. To this liquid, at the ordinary temperature, the iodosulphate of quinoidine is added drop by drop from a burette, with constant stirring, as long as a dark brownish-red pre- cipitate of herepathite is formed. As soon as all the quinine has been preci{)itated, and a slight excess of the reagent has been added, the liquor acquires an intense yellow colour. The beaker is now covered and heated on a water-bath till the liquid begins to boil, and all the precipitate is dissolved, when the liquid is allowed to cool. After standing twelve hours, the beaker is weighed with its contents. The liquid is next passed through a small filter, leaving the crystals in the beaker, which is then again weighed to ascertain the weight of the liquid. The crystals on the filter are washed back into the beaker, and as much alcohol added as is necessary to dissolve the crystals at the boiling-point. When quite cold the beaker is again weighed, the recrystal- lised herepathite collected on a small filter, and the empty beaker again SEPARATION OF CINCHONA BASES. 457 the addition of the reagent to the solution of the mixed alkaloids of cinchona bark, but it has been pointed out by Christensen, Shimoyama, and others {Pharm. Jour., [3], xii. 441, 1016; xvi. 205 ; xvii. 654), that cinchonidine, if present in notable quantity, is liable to be precipitated along with the quinine, and hence this base should be separated as completely as possible by a previous ether-treatment, as directed on page 455. The use of the iodo- sulphate of quinoidine prevents any subsequent isolation of the amorphous alkaloids of the bark under examination. Instead of converting the quinine in the ethereal solution B into herapathite, David Howard ( WaW Diet. Ghem., 2nd ed., ii. 177) agitates the ethereal liquid with excess of dilute sulphuric acid, and, after heating to boiling, adds dilute ammonia till neutral to litmus, using no more water than is necessary. On cooling, the quinine crystallises out almost entirely as sulphate, which salt is almost insoluble in a cold solution containing ammonium sulphate. The crystals are filtered off, washed with a little cold water, pressed between blotting-paper, and dried at 100° C. 73*4 parts of the anhydrous salt represent 100 parts of the crystallised sulphate. The product should be tested for cinchonidine (page 412), which may be present in small quantity. The alkaloids existing in the mother-liquor from the quinine sulphate are then recovered by concentrating the liquid somewhat, adding soda in excess, and shak- ing with chloroform. The bases are extracted from the separated chloroform by dilute acetic acid, and the solution treated as in A. The mixed alkaloids of yellow cinchona bark consist chiefly of quinine, and hence the portion soluble in ether represents the most useful constituents of the bark. Pale and red barks, on the other hand, contain a considerable proportion of alkaloids insoluble weighed. The difference indicates the weight of the mother-liquor, which is added to that of the main quantity. The recrystallised herepathite obtained as above is washed on the filter with a saturated solution of herepathite in alcohol of 92 per cent. The adhering liquid is removed as far as possible by pressing the folded filter and its con- tents between blotting-paper, and the filter is then air-dried. The precipitated herepathite is then detached from the filter, dried at 100° till constant, and weighed. The amount found is corrected by the addition of that remaining in solution, as ascertained by calculation from the weight of the mot her- liquor. One hundred grammes of alcohol of 92 per cent, dissolve "133 gramme of here- pathite at 24-5° C, and '125 gramme at 16° C. The weight of herepathite found, multiplied by '55055 gives the anhydrous, or by 0*7409 the corresponding weight of crystallised, sulphate of quinine. Instead of drying the recrystallised herepathite, it might probably be titrated with standard sodium thiosulphate solution. 21 "58 parts of iodine thus found represent 100 parts of herepathite. 458 SEPARATION OF CINCHONA BASES. or sparingly soluble in ether. Hence the use of chloroform in the general process for assaying cinchona barks (see page 451). In some cases, the alkaloids soluble in ether are contaminated to a considerable extent with colouring matter. In this event, the following is a good method of obtaining colourless quinine sulphate : — The ether-residue is dried thoroughly and weighed. It is then dissolved in 30 c.c. of absolute alcohol, and decinormal sulphuric acid cautiously added from a burette, till the liquid is neutral or very faintly acid to litmus-paper or methyl-orange. Each c.c. is equivalent to 0*324 gramme of anhydrous alkaloids. The liquid is next evaporated nearly to dryness, and a measure of decinormal sulphuric acid added equal to that previously required for neutralisation. Thirty c.c. of hot water are added, and the liquid boiled till complete solution results. Purified animal charcoal is next added, in quantity equal to the weight of the ether-residue, the liquid heated on the water-bath for twenty minutes, filtered, and the residue washed twice with boiling water acidulated with sulphuric acid. The filtrate is brought to a con- centration of 70 c.c. for each 1 gramme of ether-residue taken, and then cautiously neutralised with caustic soda, and further treated as described on page 451. Instead of commencing the separation of the alkaloids by ether, Mo ens recommends that the neutral solution of the mixed alkaloids should be treated with excess of solution of potassium sodium tartrate (RocheUe salt), which throws down the quinine and cinchonidine as tartrates. The same procedure is adopted in the British Pharmacopoeia (see page 450). The precipitated tartrates are washed with a little cold water, decomposed by excess of alkali, and the quinine and cinchonidine separated by ether ; the quinine dissolved being either directly weighed, or, preferably, converted into sulphate and tested for cinchonidine (page 412). The estimation of the relative proportions of quinine and cin- chonidine in the mixed tartrates, by observing the optical activity (page 415), has been recommended by several chemists, but in practice it is difficult to obtain the alkaloids in a sufficiently pure condition to render the results trustworthy. The following method for the separation of the cinchona bases insoluble, or nearly insoluble, in ether may be applied to the residue left on treatment of the mixed alkaloids with ether, as in De Vrij's process (page 454). It may also be applied directly to the mixed alkaloids extracted from a sample of bark, in which case it may be carried on simultaneously with Muter's process for the production of crystallised quinine sulphate as described on page 454. SEPARATION OF CINCHONA BASES. 45^ -S-g^ <= S © O ^ -M ^ P^r^ ,x3 ^3 tn M 5g ;i5 .tJ fl ?^ fi >» i^ ^ ^ -^ ^ -TZI ^ .t^ d f^ o J3 ■« M S O ■* '^ JiS'ts is ^ 4S M ai S ^ ^^ .Org ^ ^ a (_, ^ g -^^ ^ •?: p.^ tin o .22 '^ ^ 2 2 =e -g^ -M S ^ § o Si'^^ _^ -^ ■■+^ .S -tS 2 CO (D rH o o ri © « 3 "^ w r^ ■4J ij TS ^ > ' oj is o • ^>,^ 2 ® c 8 2 d § ^ © 2 ^ ^ P- © o '~^ .-^ 3 « ce ;3 © ;S .t5 es O t- Srdopd^w.Si^ g ca = H j^ d .w .^t^ o -M o 'o ni ^ d .S c3 460 TITRATION OF PRECIPITATES. The foregoing process, with experience, gives very good results, the sum of the separated alkaloids frequently amounting to 99 per •cent, of the mixed bases operated on. It is well suited for the assay of Indian barks. The least satisfactory part of the process is the separation of the cinchonine from the amorphous bases by dilute spirit. A cautious employment of ether would perhaps be preferable. If the process of separation be conducted simul- taneously with the determination of the crystallised quinine sulphate in another portion (page 454), the whole analysis can be completed in about six hours. According to Hielbig (Pharm. Zeitsch. f. Russland, 1888; Analyst, xiii. 207) the presence of much quinidine prevents the complete precipitation of the cinchonidine and quinine as tartrates ; while the precipitate with potassium iodide, if tenacious or resinous instead of crystalline, contains cinchonine, with or without quini- dine. (It seems more probable that the resinous precipitate con- sists of the hydriodides of amorphous alkaloids, which can be kept in solution by moderate addition of alcohol.) The directions in the foregoing table can be modified with con- siderable saving of time by titrating the alkaloids and their salts instead of weighing them. Thus, for the determination of the cinchonidine, the washing of the precipitated tartrate with cold water should be omitted, and the filter containing the precipitate and the adhering Eochelle salt solution immersed in boiling water. A drop of phenolphthalein solution is then added, and the liquid titrated with -^ caustic alkali. As Eochelle salt is perfectly neutral to phenolphthalein, and as tartrate of cinchonidine (and of quinine) acts just like an equivalent amount of free tartaric acid, the weight of cinchonidine can be readily calculated from the measure of standard alkali used. Each 1 c.c. of -^ NaHO neu- tralised represents 0*0147 gramme of cinchonidine (or other alka- loid) precipitated as tartrate (A. H. Allen). An exactly similar method is applicable to the treatment of the precipitate produced by potassium iodide. This should be washed with a little of the precipitant instead of with water, and then immersed together with the filter in boiling water. On titrating with -^-^ alkali and phenolphthalein each 1 c.c. of the standard solution required represents 0'0162 gramme of quinidine pre- cipitated as hydriodide.^ The chloroformic solution of the cinchonins may be directly titrated with standard acid and methyl-orange (see p. 131) instead of being evaporated to dryness ; but, of course, the amount found will include any amorphous alkaloid also extracted by the chloroform. ^ This procedure does not dispense with the necessity of making a correction for the amount of quinidine lost in the mother-liquor and washings. BERBERIS ALKALOIDS. 461 BERBERINE AND ITS ASSOCIATES. Berberine is an alkaloid occurring in a very large number of plants, in many cases in association with one or more of the alkaloids, berbamine, oxyacanthine, hydrastine, canadine, &c. It is the only natural basic colouring matter receiving practical application as a dye. The i)rincipal sources of berberine and the associated alkaloids are the roots of the following plants : — Plant. Alkaloids, &c. Berberis vulgaris (Barberry),i Berberis aquifolium, Coptis trifolia, Coptis teeta (India), .... Hydrastis Canadensis (Golden seal), Jateorhiza Calumba or Cocculus palmatus (Calumba root), Menispermum Canadense, Berberine ; oxyacanthine ; berbamine ; and at least two other alkaloids (Hess e). Berberine, 2 '35 per cent.; oxyacanthine, 2-82 per cent. Berberine, 4 per cent. Berberine, 8^ per cent.; coptinine (crystallis- able ; Gross). Berberine, ]-3 to 1-8 per cent.; hydrastine, 1*5 per cent. ; canadine ; xanthopuccine ; &c. Also meconin and phytostearin. Berberine ; columbic acid ; and the neutral principle columbin. Berberine ; oxyacanthine ; menispermine ; men- ispine. Berberine has also been found in Woodumpar, a yellow dye-wood from Upper Assam; in S t John's wood, from Rio Grande; in Berberis aristat a, Caulophyllum thalictro'ides, Coscinium fenestratum (Ceylon Calumba wood), Coelocline ;polycarpa, Podo- 'phyllum pellatwn, Xanthorhiza ayiifolia, and Xanthoxylum clava- Hercules. Hydrastine occurs also in Stylopliorum diphyllum. Berberine. C20H17NO4 ; or Ci8Hii(O.CH3),N02. Berberine is isolated from the root of Hydrastis Canadensis by boiling with water, evaporating the decoction to an extract, and exhausting with strong alcohol. One-fourth o£ its volume of water is added to the filtered alcoholic solution, the alcohol distilled off, and the residue treated with dilute sulphuric acid. Berberine sulphate crystallises out, and is decomposed by freshly-precipi- ^ A concentrated liquid extract of barberry root still receives a limited application for dyeing silk and leather yellow. In America, the root-bark is commonly used, but in Europe the entire root is generally employed. 462 CHARACTERS OF BERBERINE. tated hydroxide of lead. The alkaloid may also be converted into the sparingly soluble nitrate or hydrochloride instead of the sulphate. I^. Wolff recommends a previous treatment of the root with petroleum ether to remove fixed oil. Berberine may be isolated from barberry or calumba root by exhausting the material with alcohol, evaporating off the spirit, taking up the residue with water, and treating the filtered solution with excess of hydrochloric acid, when berberine hydrochloride crystallises out. The salt may be purified by re-solution in alcohol and precipitation by ether> Berberine crystallises with difficulty in small, concentrically grouped prisms, or bright yellow, silky needles.^ When air-dried, the crystals appear to contain 5 J aqua (W. H. Per kin, jun.), of which 3 aqua is driven off at 100". At this temperature the crystals lose their lustre and become yellowish-brown, at 110° the change is very rapid, and above 160° total decomposition occurs. Fleitmann gives 120° as the melting-point of berberine, but P e r k i n considers this figure too low.^ When warmed, berberine emits a faint but peculiar odour resembling quinone. Berberine has a persistent, very bitter taste, and is employed medicinally in doses of 2 to 5 grains. Sixty grains have been taken by man without injury, but the alkaloid is poisonous to dogs and other of the lower animals. Berberine dissolves in 500 parts of cold water, and more readiiy on boiling. The solution is neutral to litmus. It is sparingly soluble in cold, but readily in hot alcohol, and in amylic alcohol. Berberine is slightly soluble in chloroform and benzene, and in- soluble in ether (separation from oxyacanthine and hydrastine) and petroleum spirit. It is said to be taken up with difficulty ^ Berberine may also be prepared by precipitating an aqueous decoction of barberry root with lead acetate, and treating the concentrated filtrate with excess of sulphuric acid. The precipitate of berberine sulphate is washed with cold water, and separated from lead sulphate by solution in boiling water, which on cooling deposits the salt in yellow needles. 2 An orange colour, or other shade darker than bright yellow, is indicative of impurity. ^E. Schmidt has obtained some evidence that berberine pre pai'ed from the commercial sulphate is occasionally a mixture of berberine with methy 1 - berberine. He obtained pure berberine by converting the alkaloid into the acetone compound, B,C3H60, from whit;h the free base was liberated by heating in alcoholic solution. Thus obtained, berberine contained 6 aqua, all of which was lost at 100° C. The anhydrous alkaloid scarcely began to darken below 150°. REACTIONS OF BERBERINE. 463 from its acidulated solutions by amylic alcohol, chloroform, and benzene.^ When treated with a fixed caustic alkali, berberine is coloured brown, and on boiling a resinous mass separates. On distilling berberine with milk of lime, quinoline is formed. Fusion with caustic potash produces berberic acid, CgHgO^, and an acid of the composition CgHgOg. When boiled with excess of fuming hydriodic acid, two methyl groups are eliminated and a salt of berberoline, CigH^i(OH)2N02, formed. On rendering the diluted liquid slightly alkaline by ammonia, an intense blackish-blue coloration is obtained, probably owing to oxidation. Nitric acid gives, with berberoline, a magnificent violet coloration, which on standing or warming changes to a deep reddish-brown. Concentrated nitric acid dissolves berberine to a dark, reddish- brown liquid, which on dilution with water gives a yellow flocculent precipitate partly soluble in ammonia. If the dark solution of berberine in strong nitric acid be warmed oxidation rapidly occurs, with formation of berberonic acid (a pyridine-tricarboxylic acid, page 112), oxalic acid, and other products. Potassium permanganate in presence of potassium carbonate oxidises berberine with formation of hemipinic acid, Ci^HjoOg, and other products ( W. H. P e r k i n, jun., Jour. Chem. Soc, Iv. 71). By the action of nascent hydrogen, berberine is reduced to hydroberberine, CgoHg^NO^. Berberine dissolves in concentrated sulphuric acid with orange- yellow colour, changing to olive-green on warming. On adding potassium bichromate, or other oxidising agent, a black colour changing to violet (or brown-violet changing to brownish-yellow) is obtained. Frohde's reagent gives a brown or green colour with berberine ; or, according to Hirschhausen, an immediate yellow, changing through dark brown to violet-brown. Sulpho- vanadic acid is stated to give a fine violet coloration. ^ According to E. Schmidt {Pharm. Zeit., 18H7, page 542), berberine has a remarkable tendency to combine with neutral solvents, such as alcohol, ether, acetone, and chloroform, to form crystalline compounds. When berberine and chloroform are mixed in molecular proportions, they unite to form a beautiful crystalline body, permanent at 100°. This does not appear to be a mere addition-product, since it is not decomposed by acids simply into ber- berine and chloroform, but yields decomposition-products of the latter. Ber- berine can also combine with a second molecule of chloroform, but this behaves like water of crystallisation. Schmidt has also described a compound of berberine with acetone, of the formula C^ 464 SALTS OF BERBERINE. Berberine is also characterised by the insolubility of many of its salts {e.g., the chromate, picrate, hydriodide, chloroplatinate, auro- chloride), and the sparing solubility of others in presence of excess of mineral acid. On pouring chlorine-water (avoiding excess) on to a solution of berberine strongly acidulated with hydrochloric or sulphuric acid, a zone of bright red colour is formed at the junction of the liquids, and is still recognisable as a pink coloration in a dilution of 250,000.1 On cautiously adding iodised potassium iodide (avoiding excess) to a solution of a berberine salt, BHI3 is thrown down as an ex- tremely insoluble red-brown precipitate, which crystaUises from strong alcohol in red needles, or on adding water in green iridescent scales which completely polarise light. Mayer's reagent yields with berberine solutions a precipitate of the approximate composition BgHgHgl^, containing, after drying at 100°, from 50 to 52 per cent, of the alkaloid. Salts op Berberine. Berberine is a weak base, but forms definite and readily crystal- lisable salts with acids. The salts have a bitter taste, and are mostly very sparingly soluble, the pyrophosphate and acetate being exceptions. Berberine Nitrate, B,HN03, separates in fine yellow needles on acidulating a warm aqueous or alcoholic solution of berberine with nitric acid. It is soluble in about 500 parts of cold water, more readily in hot, and almost insoluble in alcohol or water strongly acidulated with nitric acid. It does not darken or undergo other change at 100° C. Berberine Hydrochloride, B,HCl+2 aq, is precipitated in golden yellow needles on adding hydrochloric acid to a warm aqueous solution of the alkaloid. It requires about 500 parts of cold water for solution, and is almost insoluble in alcohol or dilute hydro- chloric acid. The salt is with difficulty decomposed by bases, the liberated alkaloid being apt to retain chlorine. Prolonged diges- tion with litharge fails to decompose it completely, but silver oxide readily decomposes the solution. Berberine hydrochloride darkens to an orange colour when heated to about 60° C, but regains its original colour on cooling. By prolonged exposure at 100° the colour changes permanently, and much of the salt becomes readily soluble in cold water, with red colour. BHAuCl^ is amorphous, brown, and quite insoluble in water. ^ Bmcine gives a similar reaction with chlorine-water, but the original solution is colourless, and the reaction produced less permanent than with berberine. OXYACANTHINE. 46§ It crystallises from boiling dilute alcohol in chestnut brown needles, unchanged at 100°. BgHgPtClg forms a yellowish pre- cipitate, almost insoluble in all the ordinary solvents. It may be crystallised from boiling amylic alcohol, in which it is slightly soluble. Berherine Hydriodide, B,HI, obtained by precipitation, forms minute yellow needles, extremely insoluble in cold water or potas- sium iodide solution. It does not darken or suffer other change at 100°. BHIg is precipitated on cautiously adding iodised potassium iodide (carefully avoiding excess) to a solution of a berberine salt in hot spirit. It is quite insoluble in cold water. When recrystallised from hot alcohol, the smaller crystals trans- mit light which is completely polarised (compare Herepathite, page 403). Berberine Sulpliate, ^,11^0^^ is met with in commerce both in the amorphous state and crystallised. The latter form, which is consider- ably the higher piiced, can be prepared by dissolving 15 grammes of the amorphous preparation in a boiling mixture of 250 c.c. of alcohol with 8 of acetic acid, when on cooling the crystallised salt separates out. It has an orange colour, and is permanent in the air when free from impurity. It is soluble in about 100 parts of water. According to J. U. Lloyd {Ar)ier. Drug., Sept. 1884), the yellow crystalline powder obtained by heating commercial ber- berine sulphate with ammonia and shaking with ether is not the free alkaloid, as commonly assumed, but a neutral sulphate, B2H2SO4, ^hicli is readily soluble in water. BjHgCrO^ is obtained in orange-yellow needles on adding potas- sium bichromate to a boiling and very dilute solution of a salt of berberine. The salt separates entirely on cooling, and is extremely insoluble in cold water or an excess of the precipitant. Berberine Picrate requires 45,000 parts of cold water for solu- tion. As a consequence, on mixing aqueous solutions of berberine and picric acid in equivalent proportions and filtering, a liquid is obtained free from yellow colour or bitter taste. Berberine Acetate is prepared by adding berberine sulphate to a solution of a potassium acetate in rectified spirit, and heating gently till the yellow salt has dissolved. After cooling, the liquid is filtered from the potassium sulphate, evaporated to a syrup, and shaken with ether, when berberine acetate, B(C2H402)9, is pre- cipitated as a crystalline orange powder. It is readily soluble in water and alcohol, nearly insoluble in ether, and loses acid on exposure to air. OxYACANTHiNE, CigHigNOg. This base is contained in Berberis vulgaris, and remains in the mother-liquor, from which the berberine VOL. III. PART II. 2 G 466 OXYACANTHINE. BERB AMINE. has been separated as hydrochloride. The liquid is treated with caustic soda, when a dark-coloured precipitate is thrown down, from which ether dissolves oxyacanthine, berbamine, and an unnamed alkaloid, while another brown-coloured amorphous base remains undissolved. The ethereal solution is treated with acetic acid, and the resultant acetate decomposed by sodium sulphate, when oxy- acanthine sulphate is precipitated, berbamine remaining in solution. On decomposing the solution of oxyacanthine sulphate with ammonia the free alkaloid is precipitated in flocks, which, after drying at 100°, melt at 138°-150°; but when crystallised from alcohol or ether it forms anhydrous needles which melt at 208°— 214°. Oxyacanthine is readily soluble in chloroform and benzene, but only sparingly in petroleum spirit. It may be separated from berberine by extracting the ammoniacal solution with ether or chloroform. From its acidulated solutions it is not extracted by petroleum spirit or benzene, and only sparingly by chloroform. Oxyacanthine is dextro-rotatory in chloroformic solution (for 4 per cent, at 15°, S,= -f 131-6°). BHCI-J-2H2O forms small colour- less needles, the 2 per cent, aqueous solution of which shows Sd= -1-163"6°. Hot strong solutions are coloured green by ferric chloride. Oxyacanthine closely resembles narcotine. Like mor- phine, it reduces iodic acid. Concentrated sulphuric acid, with or without molybdic acid, is stated to give no colour at first, but on standing or heating a yellow colour is developed ; according to L. V. Hirschhausen {Zeit Anal. CfJiem., xxiv. 163), Frohde's reagent gives an immediate violet coloration, changing to yellowish green at the edges. When heated with caustic potash and a little water, oxyacan- thine melts to a brown mass which floats on the fused alkali. This consists of the potassium derivative of /3-o x y a c a n t h i n e, a body probably difiering from the parent alkaloid by the elements of water. A similar change occurs very readily even at the ordinary temperature, by the action of alcoholic potash or baryta on a-oxyacanthine. Ether fails to extract the ^-modi- fication from the alkaline solution. Hydrochloric acid preci- pitates /5-oxyacan thine, which is soluble both in alkalies and excess of acid. With much acid, a-oxyacanthine hydrochloride is precipitated. Berbamine, CigHij^NOg, the second Berheris alkaloid soluble in ether, was obtained by Hesse {BeiHchte, xix. 3190) by adding sodium nitrate to the liquid from which oxyacanthine had beea^b*., thrown down as sulphate. The precipitated berbamine nitrate "^ when decomposed by ammonia yields a crystalline precipitate of the free base, which crystallises from alcohol in small plates con- HYDRASTINE. 467 taining 2 aq. and melting at 156°. The salts are crystallisable and readily soluble. B2H2PtCIg is yellow, crystalline, and only slightly soluble in water. Hydrastine. C^jB-^^I^Oq; or Ci9Hi5(O.CH3)2N02 (see also page 470). This interesting base occurs with berberine (and canadine) in the root of Ihjdrastis Canadensis or Golden S e a 1.^ Perrins found 1 J per cent, in the dried root, but the yield in manufacture is from J to f per cent. It also occurs in Shjlophorum diphyllum. Hy- drastine differs from berberine in being colourless, but commercial medicinal preparations of berberine from Hydrastis are not un- frequently called hydrastine.^ Hydrastine forms colourless or milk-white four-sided prisms, melting at 132° and decomposing at a higher temperature with an odour of phenol. Free hydrastine is tasteless and odourless, but the salts have an acrid taste. The alkaloid is the chief if not the only active principle of Hydrastis Caicadensis.^ It is poisonous in large doses, 3 grains being fatal to a frog in four minutes. It resembles strychnine in causing death by arresting the respiratory move- ments in a tonic spasm. Hydrastine is insoluble in water, and nearly insoluble in alk9,line solutions. It dissolves in 120 parts of alcohol, in 1 J parts of chloro- ^F. Wilhelm extracts the coarsely-powdered root of Hydrastis Canadensis with boiUng water acidulated with acetic acid, evaporates the decoction to a syrup, and adds excess of dilute sulphuric acid. After standing, the berberine sulphate which crystallises out is filtered off, and the filtrate neutralised with ammonia. The precipitate contains much hydrastine, and on again filtering and adding excess of ammonia to the filtrate a further precipitate is produced, which is said to contain canadine. Both precipitates when boiled with ethyl acetate give solutions which on cooling deposit hydrastine in large crystals, which may be purified by crystallisation. The crystals from the second ammonia jirecipitate are much purer than those from the first. By slow evaporation of the ethyl acetate solution the hydrastine is obtained in prisms as large as walnuts. Eberhardt purifies hydrastine by dissolving tiie freshly-precipitated alkaloid in a minimum of boiling chloroform, filtering through glass-wool, and pouring the solution into excess of cold alcohol. On shaking the liquid vigorously for some minutes, the hydrastine separates as a fine crystalline precipitate, which is subjected to a repetition of the process and recrystallised from boiling alcohol. •^ The root of Golden Seal is a bitter tonic analogous to calumba. It is exhibited in the form of powder and in doses of 8 to 24 grains. The hydro- chlorides of the mixed alkaloids of golden seal are sometimes sold under the name of "hydrastine." 468 SALTS OF HYDRASTINE. form, in 16 of benzene, and in 83 of ether. It is quite insoluble in petroleum spirit. The solubility of hydrastine in ether may be utilised to separate it from berberine. Hydrastine is Isevo-rotatory, Soin chloroformic solution( 1-2759 gramme in 50c.c.) being— 67-8°.^ Hydrastine is a feeble base, and is completely extracted by chloroform from solutions freely acidulated with hydrochloric acid. In part, however, it is dissolved as hydrochloride, which salt is very soluble in chloroform. With the exception of the picrate, the salts of hydrastine are generally uncrystallisable, or are obtainable in crystals by special means only. Most of them, except the tannate and picrate, are soluble in water, the solutions having an acid reaction. Hydrastine hydrochloride and sulphate are used in medicine.^ B,HC1 is best prepared by passing dry hydrochloric acid gas over the surface of a solution of hydrastine in anhydrous and alcohol- free ether. After drying over sulphuric acid the precipitate forms a micro-crystalline powder easily soluble in water and chloroform. B,H2S04 is similarly obtained by cautiously adding a solution of strong sulphuric acid in ether to an ethereal solution of hydrastine. The salt readily takes up water and forms a gummy mass. Hydrastine solutions give no colour-reaction with chlorine-water. With iodised potassium iodide they yield a deep brown flocculent precipitate. Hydrastine may be approximately determined by titration with Mayer's reagent- (page 141), but the precipitating power of the solution is materially affected by the dilution of the liquid. Picric acid forms in hydrastine solutions a yellow amorphous precipitate of the picrate, BA-t-4 aq, which is deposited in splendid yellow needles from its solution in boiling alcohol. Solutions of hydrastine are precipitated by potassium bichromate. On touching the separated precipitate with a drop of strong sul- phuric acid, it instantly becomes bright red, the colour fading in a few seconds. This behaviour distinguishes hydrastine from strych- nine and gelsemine (page 368). If a solution of hydrastine be acidulated with sulphuric acid, and a few drops of a decinormal solution of potassium permanganate added, the colour of the reagent is instantly discharged, and an intense blue fluorescence is developed. A single drop of a 1 per 1 The figure for specific rotation given in the text is that of F r e u n d and Will. Eijkinan practically confirms this. F. B. P o w e r ( Pharm. Jour., [3], XV. 298) gives the widely different figure —170°. 2 The crystallised sulphate of hydrastine advertised by some manufacturers is simply sulphate of berberine, to which the name hydrastine is persistently misapplied. REACTIONS OF HYDRASTINE. 469 cent, solution of hydrastine when treated in this way renders a large test-tube of liquid strongly fluorescent (A. B. Lyon s, PJiarm. Jour., [3], xvi. 880). Excess of permanganate must be avoided, or both the alkaloid and fluorescent product will be destroyed. The fluorescent body differs from sesculin in not being extracted from either acid or alkaline solutions by chloroform or etlier, and in not having the fluorescence intensified by addition of alkali.i The colour-reactions of solid hydrastine have been re-investigated by A. B. Lyons (Pharm. Jour., [3], xvi. 880) with the following results : — Concentrated sulphuric acid dissolves the pure alkaloid with faint yellow colour, changing to a deep blue-purple on heat- ing. If the reagent contains a trace of nitric acid a yellow colour is produced, and with a larger proportion (1:1000) the colour is orange-red. Pure nitric acid produces a permanent orange solu- tion, which on adding water deposits an insoluble substance, and yields a liquid exhibiting an intense blue fluorescence (compare last page). With sulphuric acid and oxidising agents (compare page 368) hydrastine produces some well-defined colour-reactions. With manganese dioxide an orange colour is first developed, changing to a rich cherry-red, and passing through carmine to a yellowish shade of red, which after a time changes rather suddenly to a pale orange- yellow. This reaction distinguishes hydrastine from strychnine and gelsemine, while berberine dissolves in sulphuric acid with yellow colour, changing on addition of the oxidising agent to violet, then to chocolate-brown, and finally becoming orange-red. (The intermediate chocolate-brown stage distinguishes the berberine reaction from that given by strychnine.) Potassium permanganate gives with hydrastine and sulphuric acid the same colorations as manganese dioxide, but the changes are more rapid. A violet tint is sometimes produced after the red is developed, the contrary order being characteristic of strychnine. Frdhde's reagent gives with hydrastine a sage-green colour, slowly changing to brownish, and then gradually fading. This succession of tints is very characteristic. Sulphovanadic acid gives a rose- red colour, which fades slowly. On treating an acid solution of hydrastine with oxidising agents {e.g., manganese dioxide and sulphuric acid), it splits up into opianic acid (page 298) and hydrastinine, a base closely resembling cotarnine (page 299). If the oxidation be efi'ected in * The same fluorescent oxidation-product is sometimes developed in solutions of hydrastine by mere exposure to air. Neither pure hydrastine nor any ready- formed constituent of Hydrastis root appears to be fluorescent. 470 HYDRASTININE alkaline solution, the action proceeds further, the chief products being hemipinic (page 299) and nicotinic acids (page 111). This behaviour suggests a close relationship between hydras- tine and narcotine, but hitherto all attempts to convert one of these bases into the other have been unsuccessful.^ HYDRASTININE, Chilli NOg + HgO, pioduced together with opianic acid by the action of oxidising agents on hydrastine, forms white crystals, melting at 116°- 11 7° C, or at 100° after heating for some time to that temperature. It dissolves in water to form a strongly alkaline and very bitter solution. It is also soluble in ether, ethyl acetate, benzene, and petroleum spirit, and crystallises from each of these solvents with 1 aqua, which, however, is eliminated in the salts, a fact probably due to the formation of a closed ring. CiiH^^NOgjIICl crystallises in feebly coloured needles, soluble in water and alcohol. The aqueous solution is optically inactive and feebly fluorescent. B,B[2S04 forms yellow crystals showing a green fluorescence, and is soluble in alcohoL Hydrastinine, when treated with aqueous potash, yields hydro- hydrastinine, CiiH^gNOg, and oxyhydrastinine, CiiHi^NOg. The latter is a feeble base, melting at 97°- 98° and distilling above 350°, and forms crystallisable salts. The former base is also formed by the action of reducing agents on hydras- tinine. It forms white crystals melting at 66°, and yields crystallisable salts. When hydrastinine is oxidised in dilute alkaline solution with a cold saturated solution of potassium permanganate, it is converted almost quantitatively into oxyhydrastinine, C^^Hj^NOg. Excess of the oxidising agent and slight heating carries the oxida- tion to hydrastinic acid, CuHgNOg, a body crystallising in flat needles melting at 164°, soluble in alcohol and ether, and yielding no precipitate with silver, barium or lead salts.^ Canadine, C21II21NO4, is an alkaloid accompanying berberine and hydrastine in golden seal root. Until recently there was some doubt as to its actual existence, Lloyd having failed to detect it in the extract from a very large quantity of the root ; but F. ^E. Schmidt considers that narcotine contains three metlioxyl groups and hydrastine only two, their formulae being respectively Oi9Hi4(OMe)3N04 and Ci9Hi5(OMe)2N04. As these bases both yield on oxidation opianic acid, which contains two methoxyl groups, and cotarnine contains one such group, it follows that hydrastine contains no methoxyl, and that cotarnine has the con- stitution of a methylated hydrastinine. 2 The constitution of liydrastinine and hydrastine has been the subject of various investigations by Freund, Will, Eose, Rosenberg, Lachman, Schmidt, Wilhelm, Kerstein, Heim, Pliilips, Dormeyer, and others {Berichte, xix. 2797; CANADINE — CALUMBA ROOT. 471 W i 1 h e 1 m and E. Schmidt have independently isolated tho alkaloid, which is described as forming fine, white, shining crystals, melting at 134°, and more readily soluble than berberine in water and alkalies. The salts, with the exception of the sulphate, are soluble with difficulty in water and alcohol. B,HC1 and BgjHgSO^ are crystalline. By treatment with iodine in alcoholic solution, canadine is converted into the hydriodide of methyl-berberine, and hence it probably has the constitution of a dihydromethylene-berberine, Xanthopuccine is the name proposed by Lerchen (1878) for an alkaloid of doubtful existence occurring in hydrastis. It is described as insoluble in ether and chloroform, but soluble in alcohol and hot water. The alcoholic solution yields light brown spangles with iodised potassium iodide. Indications of other alkaloids in hydrastis have been obtained by A. K. Hale {Tear-Book Pharm., 1874, page 31) and J. C. Burt {ibid., 1886, page 95). Calumba, or Columba,^ is the root of Jateorhiza Calumha or Cocculus palmatus, a herbaceous climbing plant occurring in the forests of East Africa. The calumba of commerce consists of dried transverse slices of the root. It possesses mild bitter tonic properties, and the tincture, extract, and infusion are official preparations. The roots of bryonia and Frasera Walteri have been occasionally sold as calumba. Calumba root contains three distinct bitter principles in addition to starch (35 per cent.), gum (4*7), pectin (17), resin, wax, and XX. 80, 2400; xxii. 456, 1156, 2322, 2329; xxiii. 404, 416, 2469, 2897, 2920; xxiv. 2730, 3164; Arch. Pharm., [3], xxvi. 329; xxviii. 49, 221). M. Freund {Ber., xxii, 2329) suggests the following structural formulae for hydrastinine and its derivatives : — Hydrohydrastinine, . . CHgJ q hCgHgj qjj'qjj r Hydrastinine, . . . CHaj q jCsHsl cH^.CHa ^} Oxyhydrastinine, . . . CHaj q jCfiHaj qjj'^ qjj® | For hydrastine itself Freund suggests the following formula : — CH2-[Q|CeH2(CH2.CHj.NHMe).C:C.C6H2(OMe)2.COOH. On decomposition into hydrastinine and opianic acid, fission would take place at the point of triple linkage, both the acid and the basic derivative possessing aldebydic functions. ^ German : Kalurriba or Columho wurzel. French ; Racine de Columbo. 472 COLUMBIN. mineral matter (6 per cent.). Potassium nitrate has been found, but not tannin. Berberine, the characteristic yellow alkaloid of calumba root has already been described (page 462). CoLUMBiN, or Calumba Bitter, C21H22O7, exists in calumba root to the extent of 0'34 to 0'40 per cent. To extract it, the material is exhausted with boiling alcohol, the extract evaporated to dry- ness, the residue taken up with hot water, and the filtered liquid shaken with ether ; or the tincture is evaporated to a syrup, and shaken with chloroform. The chloroform solution is filtered, evaporated, and treated with 60 per cent, alcohol, which dissolves most of the colouring matter. The residue is dissolved in strong alcohol, the solution decolorised with animal charcoal, and the columbin crystallised. Columbin is an intensely bitter, inodorous, neutral body. It melts at 182°, and crystallises from acetic acid solution in colourless trimetric prisms, very slightly soluble in cold water, more freely in hot. Columbin is sparingly soluble in cold alcohol, and in 40 parts of the boiling solvent. It dissolves with difficulty in cold ether, more readily in hot, and may be separated from berberine by agitating the acidulated liquid with this solvent. The solution of columbin is intensely bitter ; it is not precipitated by tannin or any metallic salts. Columbin dissolves in strong sulphuric acid with orange colour, changing to deep red ; on adding water brown flakes are deposited. Columbin dissolves in aqueous alkalies, and is reprecipitated by acids. On heating with caustic alkali an acid body is formed. According to H u d e, columbin produces vomiting and diarrhoea. O'lO gramme was fatal to a fowl, death being preceded by diges- tive disturbance and frequent evacuations {Pharm. Jour., [3], xvi. 838). CoLUMBic Acid, CggHg^Og + HgO, is prepared by treating the dried alcoholic extract of calumba root with lime-water, and pre- cipitating the solution with hydrochloric acid. It is a yellow amorphous body, somewhat less bitter than columbin; nearly insoluble in water, but little soluble in ether, more readily in acetic acid, and easily in alcohol. The alcoholic solution precipi- tates lead acetate yellow. CAFFEINE AND ITS ALLIES. Caffeine, the characteristic alkaloid of coffee, was obtained pure in 1821, when it was prepared almost simultaneously by Runge, Pelleticr and Caventon, and Robiquet. In 1827, Oudry XANTHINE DERIVATIVES. 473 discovered a similar principle in tea, and named it theine. B e r z e 1 i u s suggested the identity of this with caffeine, and this was afterwards established, as also was that of the alkaloid of guarana, called by Martins guaranine. Mate, or Paraguay tea, and Kola nuts contain the same alkaloid, while cocoa contains the alkaloid theobromine (which may be regarded as a lower homologue of caffeine) in addition to small quantities of caffeine. Unlike the majority of the alkaloids hitherto described, theo- bromine and caffeine are not related to pyridine or quinoline. They are respectively the di- and tri-methyl-derivatives of xan- thine, C5H4N4O2, a weak base forming the chief constituent of cer- tain rarely-found urinary calculi, and existing constantly to a minute extent in normal urine and in most of the organs of the human body. Xanthine itself is closely allied to u r i c acid, Cgll^K^Og, from which it differs by a single atom of oxygen, and from which it can be produced by treatment wath sodium amalgam and water. On adding silver nitrate to an ammoniacal solution of xanthine, an amorphous precipitate of the silver-derivative, CgHgAggN^Og, is formed, and this when heated with methyl iodide is converted into dimethyl-xanthine or theobromine, €5112(0113)2X402. When the silver-derivative of theobromine, C5HAg( 0113)21^402, is heated with methyl iodide to 160° 0. for twenty hours, trimethyl- xan thine or c a f f e i n e, C5H(CH3)3N402, is produced. The following formulae show the constitution of caffeine and theobromine, and their relation to xanthine -} — Xanthine, . . HN OH* I II 00 0— NH I I >00* Theobromine, . . CH3.N OH* I II 00 0— KOH3 I I Noo* HN N/ Caffeine, . . OH3.N OH* 1 II 00 0— KOH3 ' I \oo* CH3.N 0=K/ ^ The formulae given in the text are those proposed by Emil Fischer (Annalen, ccxv. 314). In the formulse of M e d i c u s {Annalen, clxxv. 250), the CH and CO groups marked with an asterisk are transposed. 474 SOURCES OF CAFFEINE. Theophijlline (see page 498), a base isomeric with theobromine, has been found in minute quantity in tea, as also has xanthine itself.^ Caflfeine.^ Theine.^ Trimethyl-xanthine. Methyl-theobromine. CgHioNA; orC5H(CH3)3lsr,02. The constitution and synthesis of caffeine have already been described (see page 473). Caffeine exists naturally in the following sources, all of which are employed for food or preparing beverages : — a. C f f e e ; 2 the dried seed of Goffea Arabica. b. T e a ; 2 the prepared and dried leaves of Camellia Thea. c. Mat^ or Paraguaytea; the dried leaves and twigs of Bex Paraguay ensis. d. Guarana or Brazilian chocolate; the dried pulp of the seed of Paullinia sorbilis. e. Cola; the seeds or nuts of the Kola tree ( Cola or Sterculia acuminata) of West Central Africa. Caffeine is found in other parts of these plants besides those commonly used for food, and also occurs in small quantity, together with theobromine, in cocoa. Caffeine can be isolated with facility in a state of considerable purity, but its quantitative determination is attended with con- siderable uncertainty, chiefly owing to the difficulty of completely extracting it from its natural sources (see page 488). Caffeine is now prepared on a considerable scale from damaged tea.3 Several methods have been employed for the purpose, one of the simplest being to exhaust the tea with boiling water, boil ^ For the isolation of xanthine from tea, A. Baginsky extracted the material with dilute sulphuric acid, treated the clear liquid with baryta-water in excess, and then passed carbon dioxide to precipitate the excess of baryta. After filtering and evaporating, ammonia and silver nitrate were added, and the resultant precipitate of xanthine-silver crystallised from its solution in dilute nitric acid to which some urea had been added. The xanthine-silver nitrate obtained contained 33 "6 per cent, of Ag, or very nearly the amount required by the formula C5H4N4O2, AgNOg. The weight obtained foom 1 lb. of tea was only 0*1567 gramme [Pharm. Jour., [3], xix. 41). ' The absolute identity of the alkaloids of tea and coffee is generally accepted, but cannot be said to have been established absolutely beyond doubt. According to Lauder Brunton and Cash {Proc. Royal Society, 1887), the physiological effects of the alkaloids extracted from tea and coffee exhibited marked differences. Theine (from tea) appeared to be more powerful in its action than caffeine (from coffee), and tended to produce rhythmical contractions of the voluntary muscles. These observations have not been confirmed. '^ A few years since the manufacture of caffeine was almost monopolised by Germany. In consequence of a revised regulation of the English customs, CHARACTERS OF CAFFEINE. 475 the decoction with litharge or acetate of lead, and concentrate the filtered sohition till the alkaloid crystallises out on cooling. The product can be purified by resublimation, or by crystallisation from hot water. Cafi'eine forms long, white, silky, flexible needles, which readily felt together to form light fleecy masses. When deposited slowly from an aqueous or chloroformic solution, the crystals of cafi'eine present a characteristic appearance under a magnifying power of 100 to 300 diameters. It is generally stated that caffeine crystallises from water with 1 aqua (8*49 per cent.), but the proportion ordinarily present in crystallised cafi'eine is sensibly less than corresponds to this formula. ThusPfaff and Liebig found 7-85 and Martins 8'14 per cent., and the author in two commercial specimens obtained 7*05 and 7*10 per cent.^ It is probable that the deficiency is due to efflorescence, for the water of crystallisation is lost by prolonged exposure over concentrated sulphuric acid at the ordinary tem- perature and pressure, so that the caffeine so treated suffers no further loss of weight at 100°. On heating crystallised caffeine to 100° C. the crystals become opaque and friable, consequent on the loss of water, the residue consisting of anhydrous caffeine and dissolving without turbidity in chloroform. According to Mulder, caffeine is deposited in anhydrous crystals from alcohol or ether, and under certain con- ditions from water also. It is possible that hydration may depend on unrecognised conditions, such as those of temperature and con- centration of the solution at the time of separation, and that com- mercial caffeine is a variable mixture of anhydrous and hydrated crystals. Caffeine does not evaporate with vapour of water, and undergoes no appreciable change of weight at 100° (A. H. Allen).^ At 120° it volatilises very gradually, and at a higher temperature sublimes unchanged in long, silky needles. according to which damaged tea is admitted duty-free, provided that it be *' denatured" and rendered wholly unfit for human consumption by treatment with lime and assafcetida, it has become possible to use such tea profitably for the manufacture of caffeine. As a result, England has become the chief seat of the manufacture, and now exports the alkaloid to Germany and America. At present (August, 1892) the retail price of caffeine from tea is 9d. per ounce. ^ Mulder found 8 "49 per cent, of water, but that was by exposing the substance to a temperature above 120°, when more or less volatilisation must have taken place. 2 The statements respecting the effect of heat on caffeine are very discordant. According to A. Wynter Blyth, caffeine sublimes in minute needles at 476 CHARACTERS OF CAFFEINE. At 23r-233° C. cafifeine melts to a clear liquid, and at 384° (S t r e c k e r) boils and distils with partial decomposition, leaving no residuum. 79° C, and volatilises completely at 120°. Other observers give much higher temperatures for its subliming point. The behaviour of caffeine when heated has an important bearing on the methods of determining the alkaloid, and hence has recently been carefully re-investigated in the author's laboratory by G. E. Scott Smith, C. M. Caines, and G. S. A. Caines. The following facts have been fully established : — 1. Commercial caffeine (crystallised) lost 6*9 per cent, of its weight by prolonged drying over concentrated sulphuric acid at the ordinary temperature and pressure. 2. Caffeine which has been dried at the ordinary temperature over sulphuric acid till constant in weight undergoes no further material loss on prolonged exposure in an open dish in the water-oven at 100°. The following results were obtained : — Caffeine. Loss. Weight of commercial alkaloid taken, 1-000 gramme. ... „ after long exposure over H2SO4 at 20° C, 0-931 6-9 per cent. „ after heating in water-oven for 2J hours, 0-929 „ 71 „ II II l> "5 II 0-929 „ 7-1 II 51 „ 0-927 „ 7-3 „ 3. Notwithstanding the foregoing results, on heating caffeine contained in a watch-glass, covered with another watch-glass, over boiling water or on the top of the water-oven for fifteen minutes, a distinct film appeared on the covering glass, and crystals of caffeine were observable under the microscope. The slight loss of weight observed when caffeine was exposed for many hours at 100° is doubtless due to volatilisation. 4. On exposing dry caffeine to a temperature of 120° in an air-bath, a very gradual but continual decrease of weight was observed, indicating sensible volatilisation of the alkaloid at the temperature employed. Thus : — Weight of Alkaloid. Loss. Grammes. Grammes. Per cent. Moisture-free caffeine taken, 0-9290 ... After heating for 2 hours at 120% 0-9260 0-0030 0-32 6 „ 0-9270 0-0220 2-37 11 „ 0-8668 0622 6-69 14 1, 0-8314 0-0976 10-50 17 .1 0-7850 0-1440 15-50 II 20 „ „ 0-7654 01536 16-53 24 „ 0-7568 0-1722 18-53 i> t> 29 „ „ 0-7486 0-1804 19-42 CHARACTERS OF CAFFEINE. 477 Caffeine is odourless, but has a bitter taste. It has a marked phy- siological action, and in excessive doses possesses decided poisonous properties. Administered to frogs, it produces tetanus and rigor of the voluntary muscles. A cat was killed in thirty-five minutes by administering J gramme of alkaloid. In all experiments with caffeine on the lower animals there has been increased frequency of the heart's action, and repeated emptying of the bladder and intestines. After death, the alkaloid has been detected in the blood, the bile, and the urine. In man, caffeine increases the heart's action, by stimulating the cardiac muscles, and excites the nervous system. The British Pharmacopoeia gives from 1 to 5 grains as the medicinal dose of caffeine ; the German Pharmacopoeia states the maximum single dose at 0*2 gramme, and the daily maximum dose at 0"6 gramme. The physiological action of infusions of tea and coffee is in part due to the caffeine, but is largely modified by the other constituents; notably the tannin, extractive matter, and pos- sibly the essential oil of tea, and the catfeol or essential oil of coffee. Caffeine is only sparingly soluble in cold water (75 to 80 parts), but tolerably readily in hot (10 parts). It dissolves in about 35 parts of cold rectified spirit, but it is much less soluble (1 : 155) in absolute alcohol. In cold ether it is very sparingly soluble, more readily in amylic alcohol, chloroform and benzene, but nearly 5. Caffeine which had been recently sublimed and was consequently anhydrous, melted at 231 -6° C. , and resolidified at 223° C. Strecker gives the melting-point of anhydrous caffeine as 234°, and Biedermann at 230*5°. Mulder gives the melting-point at 177 "8°, which is certainly too low. 6. Caffeine which had been recently sublimed and then dissolved in water, alcohol, ether or chloroform, in each case left the original weight of alkaloid on evaporating the solution and exposing the residue at 100°. The same result was obtained with recently-fused caffeine. As sublimed and fused caffeine are certainly anhydrous, it follows that the alkaloid left on evaporat- ing its solutions in the above solvents is also anhydrous. 7. When a known weight of caffeine was repeatedly treated with a small quantity of water, and the liquid evaporated to dryness at 100°, the original weight was always recovered. When caffeine, previously dried at 100° or 120°, or recently sublimed or fused, was dissolved in 1000 parts of distilled water, the solution concentrated by boiling over a naked flame, and the evaporation completed in a platinum dish at 100°, the residue being finally dried in the water-oven, the weight of alkaloid originally taken was strictly recovered. This proves that caffeine does not volatilise with steam during the evaporation of its solutions (A. H. Allen, Pharm. Jour., [3], xxiii. 213). 478 DECOMPOSITION -PRODUCTS OF CAFFEINE. iQSoluble in carbon disulphide and petroleum spirit.^ Chloroform and benzene dissolve out the alkaloid even from its acidulated aqueous solutions, but the agitations must be several times repeated to effect complete extraction. Concentrated sulphuric acid converts caffeine into the sulphate, but does not colour or otherwise change it even at 100° C.^ Hydrochloric acid has no action on caffeine below 200°, but when heated under pressure with concentrated hydrochloric acid to 250° for six to twelve hours caffeine yields ammonia, methylamine, sarcosine, carbon dioxide, and traces of formic acid. The volume of methylamine produced is double that of the ammonia, which proves the presence of three NMe groups in caffeine, and estab- lishes the following formula for the reaction: — C8H^o^^^^2 + 6H2O ^ NH3 + 2N(CH3)H2 + C3H7NO2 -f CH2O2 + CO2 (K Schmidt, Annalen, ccxvii. 270).^ When caffeine is warmed with dilute caustic alkali or boiled with concentrated baryta-water, it at first assimilates the elements of ^ A. Coramaille {Compt. Bend., cxxxi. 817 ; Jour. Chem. Soc. xxix. 779) gives the following figures for the solubility of hydrated and anhydrous caffeine in different menstma : — Parts of Solvent required for 1 of Caffeine. Solvent. At 15° to 17° C. At Boiling- point of Solvent.* Hydrated. | Anhydrous. | Anhydrous. Water, Rectified spirit, . Absolute alcohol, . Commercial ether, Pure anhydrous ether, Chloroform, . Carbon disulphide, Petroleum ether, . 68 40 476 74 44 165 526 2288 7-7 1709 4000 2-2 32 277 H 220 * The hot water was at 65° only, not at the boiling-point. ^ Experiments by the author showed that pure catfeiue was wholly unchanged when heated in the water-oven for several hours with concentrated sulphuric acid. On dissolving the product in water, boiling with oxide of lead, filtering, concentrating, and extracting with chloroform, the original weight of caffeine was recovered. Some samples of commercial caffeine darken slightly when heated with sulphuric acid. 3 Schmidt thought it possible that theobromine might be formed in this reaction by the elimination of a methyl-group, but was not able to detect it. The methylamine was separated and purified by conversion into the chloro- platinate. The sarcosine was identified by means of its copper salt. CAFFEIDINE. 479 water and is converted into an acid containing CsH^gN^Og.^ On further treatment, this body splits up with great facility into carbon dioxide and the base caffeidine, CyHjgN^O.^ On still further boiling with the alkali this is again decomposed with forma- tion of carbon dioxide, formic acid, ammonia, methylamine, and sarcosine (methyl-amidoacetic acid). The author has proved that caffeine readily undergoes decom- position when boiled with lime-water, a fact which has a practical bearing on several of the published processes for its determination. When caffeine is boiled with magnesia and water, the decomposi- tion is insignificant, and with litharge there is no change. ^ Caffeidine-carboxylic Acid, C8HioN403, or C7H11N4O.COOH, is best prepared by digesting finely-divided caireiue for some hours at 30° C. iu a dilute solution of caustic potash or soda, neutralising with acetic acid, adding cupric acetate (avoiding excess), and decomposing the resultant precipitate by sul- phuretted hydrogen. The libeiated acid obtained on evaporation of the filtrate in vacuo at the ordinar}' temperature, may be purified by solution in chloroform and precipitation with benzene, and is thus obtained in the form of a thick oil, which ou exposure to the air solidifies to a yellowish-white, slightly crystalline mass, very soluble in water to a strongly acid liquid. It is soluble in alcohol and chloroform, but insoluble iu benzene. On boiling the aqueous solution of caffeidine-carboxylic acid, carbon dioxide is evolved and a reddish oil remains, which when stirred up wiili a small quantity of sulphuric acid and treated with alcohol solidifies to a white crystalline mass of caffeidine sulphate. The reaction affords a ready method of prejiariug caffeidine. It IS merely necessary to decompose the copper salt with sulphuretted hydrogen, evaporate the filtrate rapidly, and treat it with strong sulphuric acid. The copper salt of caffeidine-carboxylic acid, Cu(CioHiiN403)2, is a pale blue crystalline powder, nearly insoluble in water and wholly so in alcohol. The barium, calcium, zinc, cadmium, and magnesium salts are nearly insoluble in water, but the lead salt is soluble. KA is a yellow oil. On adding mercuric chloride to the solution of a soluble caffeidine-carboxylate, a copious white precipitate is obtained which appears to contain (CgHiiN'403)2Hg,2HgC1.2. If this be sus])ended in water and decomposed with sulphuretted hydrogen, the filtered liquid leaves caffeidine hydrochloride on evaporation. 2 Caffeidine, C7H12N4O, may be obtained as above described, or may be prepared by boiling caffeine with a solution of 10 parts of crystallised baryta for half an hour, or until ammonia and methylamine begin to be evolved. From the product of the reaction, caffeidine sulphate, BH2SO4, is obtained by acidulating the filtered liquid with dilute sulpliuric acid, and evaporating the filtrate to a thin syrup, when the salt is deposited in readily soluble needles. The free base is an oily, strongly alkaline liquid, readily soluble in water, alcohol and chloroform, but with difficulty in ether. It reduces silver oxide, even in the cold, and decomposes very readily into ammonia, methylamine, and cholestrophane (dimethylparabanic acid), CgHoMe.^NgOg. Caffeidine nitrate, hydrobromide, and hydrochloride crystallise well. B.^HaPtClg crystal- lises from water in large orange-yellow needles, containing either 2 or 4 aqua. 480 MUREXOiN TEST. When caffeine is heated with soda-lime to 180*', ammonia is evolved, and carbonate and a large quantity of cyanide formed. According to Rochleder this last product distinguishes caffeine from piperine, morphine, quinine, and cinchonine. When caffeine is ignited with excess of soda-lime, the nitrogen is evolved as ammonia, any cyanide formed as an intermediate product at a lower temperature being decomposed in the usual manner; but in order to ensure com- plete conversion of the nitrogen into ammonia, it is better to mix the caffeine with about twice its weight of cane-sugar (A. H. Allen). When caffeine is treated with bromine-water, avoiding excess, and the liquid evaporated to dryness at 100°, a yellowish residue is left, which becomes crimson-red on further heating, and is turned a magnificent purple by ammonia. The reaction is very delicate, and is not affected by a considerable excess of ammonia. On adding caustic soda complete and instant decolorisation occurs. Another modification of the test consists in treating a minute quantity of the solid substance (such as a residue of caffeine left on evaporation) in a porcelain dish with a few drops of strong hydro- chloric acid and a minute crystal of potassium chlorate, and evapo- rating the liquid to dryness at 100°. When cold, the reddish-yellow or pinkish residue is cautiously moistened with ammonia, avoiding an excess, when the characteristic purple coloration is produced ; or, preferably, it is exposed to ammoniacal vapours by inverting the dish bearing the residue over another containing strong ammonia. The products of the oxidation of caffeine include a m a 1 i c a c i d,^ which by subsequent treatment with ammonia is converted into murexoin; the reactions being identical to the eye and parallel in chemical change to those yielded by uric acid under like conditions. Thus : — Uric acid yields Caffeine yields With the oxidising agent, . Alloxantin. A malic acid. CgHeNA C8H,(CH3)4N408 On adding ammonia, . . . Murexide. Murexoin. NH4. CsB.-N.O, NH4. CsCCHa)^^^©^ Strong nitric acid may be substituted for the bromine-water or liydrochloric acid and potassium chlorate ; but the reaction is in that case far less distinct and easy to regulate, and excess of am- monia must be carefully avoided.^ ^ Amalic Acid forms colourless crystals which stain the skin red, and are very sparingly soluble in water or alcohol. It reduces silver salts, and forms deep violet compounds with potash, soda, and baiyta. '^ 0. H eh n er, in a private communication to the author, points out that, if the nitric acid used be perfectly pure, caffeine fails to give the murexoin reaction, but that in presence of a minute trace of hydrochloric acid the coloui is readily developed. REACTIONS OF CAFFEINE. 481 Theobromine and xanthine give similar reactions to caffeine with an oxidising agent and ammonia. The purple colorations due to caffeine and theobromine are decolorised by adding caustic alkali solution, but that due to uric acid is changed to blue. When caffeine is heated with a large excess of nitric acid, it is converted into cholestrophane^ or dimethylparabanic acid, C3(CH3)2]Sr203, a body which crystallises in pearly laminae, melting at 145-5°, boiling at 275°-277°, and difficultly soluble in cold water and alcohol. It is decomposed with great facility by alkalies into symmetrical dimethylurea (melting at 97°-100°) and oxali c acid. Hence on adding ammonia and calcium chloride to its aqueous solution, and warming the liquid, calcium oxalate is precipitated. Cholestrophane is also produced (35"4 to 41*8 per cent.) by oxidising caffeine with chromic acid mixture, the main reaction being : — C5H(CH3)3N402 + O3 + 2H,0 » C3(CH3)2N20, + NH2(CH3) + NH3 + 2CO2 . Caffeine is very imperfectly precipitated by the usual alkaloidal reagents. No reactions result with iodised potassium iodide and Mayer's solution, which behaviour distinguishes caffeine from nearly all other alkaloids except theobromine and colchicine. Potassio- bismuth iodide precipitates caffeine after a time from moderately dilute solutions (1 : 3000). Phosphomolybdic acid produces a yellowish precipitate, soluble in warm sodium acetate solution, the liquid depositing free caffeine on cooling. (C8HjQN'402.HCl)2PtCl4 is obtained on adding hydrochloric acid and platinic chloride to a highly concentrated solution of caffeine, as an orange precipitate soluble in 20 parts of cold and an even smaller quantity of warm water, crystallising again on cooling. A solution of caffeine in 200 parts of water gives an immediate and abundant precipitate on adding a saturated solution of mercuric chloride. With a more dilute solution (1 : 1000) crystals appear in a few minutes, and in an hour or two an abundant crop of large acicular crystals is obtained. With a solution of caffeine in 4000 of water crystals appear after a few days. The precipitate con- tains C8HjQN402,HgCl2, and is much less soluble in excess of the reagent than in pure water. Hence the best results are obtained by adding an equal measure of a concentrated solution of mercuric chloride to the liquid to be tested. The compound is soluble in about 260 parts of cold water, and more readily in hot, crystallising out again on cooling. It also crystallises from hot alcohol. The ^ The name cholestrophane is due to Stenhouse, and has reference to the resemblance the crystals have tocholesterin (Vol. II. page 312). VOL. III. PART II. 2 H 482 SALTS OF CAFFEINE. compound is not sufficiently insoluble to be applicable to the quantitative precipitation of caffeine (R. H. D a v i e s, Pharm. Jour.^ [3], xxi. 253). Gallotannic acid precipitates moderately dilute solutions of caffeine, the precipitate being somewhat soluble in excess of the reagent. A difference of a few degrees in temperature greatly alters the solubility, and hence a solution of properly adjusted strength may be perfectly limpid at one temperature, and become completely opaque from separation of amorphous caffeine gallo- tannate on cooling a few degrees. A similar separation of caffeine tannate is the cause of an infusion of tea becoming turbid on cooling. Salts of Caffeine. Caffeine is a very feeble base. Its aqueous and alcoholic solu- tions have no action on litmus, and it is extracted from aqueous liquids by benzene and chloroform, even in presence of a free mineral acid. This behaviour is doubtless due to the facility with which the majority of caffeine salts are decomposed on dilution. They are decomposed by alcohol and ether as by water, and the salts with volatile acids (e.^., acetic) are decomposed on exposure to air. The hydrochloride leaves merely free caffeine on exposure to 100° C. The author found that on adding free caffeine to hot water containing a trace of sulphuric acid and coloured with methyl orange, the red colour of the liquid was immediately destroyed, proving neutralisation of the acid ; but an acid reaction was re- established when standard acid had been added equivalent to only about ^ of the caffeine present. Owing to these facts, certain devises have to be employed for the preparation of the majority of the salts of caffeine. The oxalate ^ and salicylate are sparingly soluble, and can be readily prepared by mixing equivalent quantities of the acid and alkaloid in aqueous solution. The citrate is best obtained by mixing a chloroformic solution of caffeine with an alcoholic solution of citric acid, and evaporating the mixture to a syrup. "When molecular proportions of caffeine and a mineral acid are mixed together in presence of excess of water, no combination ensues. If the quantity of water is insuihcient to dissolve the alkaloid, the latter remains suspended in the liquid in an unchanged condition. If the liquid is allowed to evaporate spontaneously, the acid ultimately becomes sufficiently concentrated to act on a portion of the caffeine, and a true salt crystallises out, intermingled 1 Caffeine oxalate is said by Leipen to be an exceptionally stable salt. It can be recrystallised from water ; but the author found that the whole of the cafifeine could be removed by chloroform from an aqueous solution containing a considerable excess of oxalic acid. SALTS OF CAFFEINE. 483 with crystals of the unaltered alkaloid. But as the acid is weakened by its combination, the formation of the salt is retarded till further concentration has taken place. Hence the change is progressive and continuous, the caffeine gradually dissolving and again crystal- lises out as a salt, though at the very last crystals of the uncombined base can be observed in admixture with the increasing crop of the true salt. By employing a considerable excess of acid the process is greatly hastened, and a product free from uncombined alkaloid is obtainable. With an excess of acid, and at a sufficient degree of concentration, the alkaloid will momentarily dissolve to a clear solution, and then almost immediately crystallise out as salt. The foregoing observations are due to H. W. Snow (Pharm. Jour., [3], xxi. 1185), who gives the following as the composition of the principal salts of caffeine : — Caffeine hydrochloride, . . B,HC1 + 2H20 Caffeine hydrobromide, . . B,HBr + 2H20 Caffeine nitrate, . . . . 5(B,H]Sr03) + H20 Caffeine sulphate (normal), . . B.HgSO^ Caffeine oxalate, . . . B2,H2C204 Caffeine salicylate, . . B,HC7H503 Caffeine hydrochloride crystallises in colourless prismatic needles. It loses the whole of its acid at 75° C. The sulphate is deposited from a hot alcoholic solution in shining needles unchanged at 100°. Caffeine nitrate forms fine transparent crystals, which when dropped into water become opaque, and are converted into pseudomorphs consisting of microscopic needles of free caffeine. Caffeine citrate is official in the British Pharmacopoeia of 1885, where the formula C^-^^ fi^^^G^fiyj is ascribed to it. The B.P. article is generally regarded as an indefinite, unstable, in- accurately described, and superfluous preparation {Pharm. Jour.^ [3], xix. 252). Free caffeine has not unfrequently been sold as the citrate. The proportion of acid can be directly ascertained in the citrate and other caffeine salts by titrating the solution with a standard caustic alkali (or preferably baryta) and phenolphthalein, and the total caffeine can be isolated by agitating the neutralised or original aqueous solution with chloroform. On treating the dry substance with cold chloroform, only the uncombined caffeine, if any, will be dissolved out (J. U. L 1 o y d). A strong and stable solution of caffeine can be readily prepared by dissolving it in benzoate, cinnamate, or salicylate of sodium or ammonium. Such solutions are employed for hypodermic injec- tions, and caffeine phenate and phthalate have been applied to the same purpose. ib4 ISOLATION OF CAFFEINE. Isolation and Determination of Caffeine. Kone of the compounds of caffeine are sufficiently stable or insoluble to be of service for the separation or precipitation of the alkaloid, which is always determined by weighing it in the free state. The isolation of caffeine presents no difficulty, and may be effected by a variety of methods. The majority of these depend on the treatment of the substance or its m^ueous infusion with lime, magnesia, litharge, or basic lead acetate, to render the tannin, &c., insoluble ; and crystallisation of the caffeine from the concen- trated filtrate, or extraction of it by benzene, ether, or chloroform. To ensure the absence of inorganic salts, the alkaloid should be sublimed or shaken out from its aqueous solution by chloroform. Provided that the caffeine isolated be well crystallised, colourless, free from acid or alkaline reaction to litmus, completely soluble in chloroform, exerts no reducing action on Fehling's solution, and leaves no ash on ignition, it may be regarded as pure. Although tlie isolation of caffeine in a state of absolute purity may be easily effected, the accurate determination of the propor- tion of alkaloid present, especially in tea, is attended with great difficulty, and hence most of the published results represent the proportion of caffeine isolated, rather than the amount existing in the substance examined. When once in solution, several methods may be used, though even in this case some of the published pro- cesses give results which are very gravely wide of the truth. As a consequence, the great majority of the published determinations of caffeine are completely worthless, and even where a number of figures have been obtained by the same process they do not necessarily bear any definite relation to each other. The determination of the alkaloid in tea has recently been the subject of a very large number of experiments in the author's laboratory by C. M. Caines, G. S. A. Caines, and G. E. Scott Smith (Pharm. Jour., [3], xxiii. 215). The following facts have been fully established : — 1. Aqueous solutions of caffeine, even when very dilute, may be concentrated by boiling, and subsequently evaporated to dry- ness at 100° without the least loss of alkaloid (see page 477). 2. Caffeine may be completely dehydrated at 100° in the water- oven. It undergoes no appreciable loss by volatilisation when exposed to 100° for many hours; but sublimation to a minute extent can be proved by the aid of the microscope (see page 476). 3. Caffeine cannot be estimated, even approximately, by crystal- lisation from water, the amount which remains obstinately in solu- tion, in the presence of saline matters, often exceeding that which can be separated as crystals. EXTRACTION OF CAFFEINE. 485 4. Cali'eine can be comi)letely extracted from its acidulated or slightly anmioniacal aqueous solutions by repeated agitation with chloroform. In the author's experiments, from a solution slightly acidulated with sulphuric acid, the first treatment with chloroform extracts from 70 to 85 per cent, of the total alkaloid. Four treatments with chloroform usually effect the complete extraction of the alkaloid; but it is desirable to agitate a fifth time and evai)orate the separated solvent apart, to prove that no more caffeine is being dissolved. In this last case, the solution may be advantageously rendered ammoniacal, or a loss of O'OOl to 0*002 gramme of cafieine may occur, probably owing to the existence of traces of caffeine sulphate, especially where the solution is strongly acidulated with sulphuric acid. On distilling the chloroformic solution of caffeine, and drying the residue at 100° C, the alkaloid is obtained in a perfectly anhydrous condition. 5. Charcoal cannot be employed for decolorising caffeine solu- tions, without a considerable absorption of alkaloid, which is retained with extreme persistency. If the caffeine isolated be coloured, it may be dissolved in a little hot water, and the filtered solution evaporated to dryness; but there is little difficulty in isolating the alkaloid in a snow-white condition. 6. Caffeine is completely unchanged by heating to 100° with strong hydrochloric acid, or with sulphuric acid diluted with one- third of its measure of water. On treating the mixture with water, the whole of the alkaloid may be recovered by agitation with chloroform, as in 4. 7. Caffeine is readily decomposed by alkalies. By warming with dilute caustic soda, it easily undergoes change, and by boil- ing with lime it is partly decomposed, with formation of ammonia and methylamine (see page 479). 8. When commercial caffeine is treated with ignited magnesia and water, and the mixture distilled, a sHght but distinct formation of ammonia is observed, apparently accompanied with traces of volatile amines. But the volatile bases are found chiefly in the first fractions of the distillate, the latter portions being quite free from alkaline reaction; and when carefully purified caffeine is employed, the formation of ammonia and other volatile bases is reduced to a minute trace. Hence tlieir formation is more probably due to the decomposition of some impurity present in small quantity than of the caffeine itself, as in the latter case the pro- duction would continue throughout the distillation. On filtering from the magnesia and extracting the filtrate with chloroform, the original weight of caffeine can be recovered, if the pure alkaloid was originally employed. 486 DETERMINATION OF CAFFEINE. 9. If a mixture of caffeine with magnesia be made into a paste with water and dried, the alkaloid can be wholly extracted from the mixture by prolonged treatment with chloroform. 10. When one part of caffeine is dissolved in hot water, and a solution of two parts of gallo tannic acid added, the caffeine can be accurately determined by precipitating the solution with lead acetate and extracting the concentrated filtrate with chloroform. If the liquid be concentrated to a syrup, mixed with ignited magnesia, and dried at 100°, the whole of the alkaloid cannot be extracted by boiling the powdered mass with dry chloroform, however long the treatment be continued. If tannin prepared from tea be substituted for gallotannic acid in the foregoing experiment, a similar result is obtained. 11. When a decoction of tea is substituted for the foregoing artificial mixture of caffeine with excess of tannin a precisely similar result is obtained. Whether sand or magnesia be used, the alkaloid is only partially extracted, even after prolonged boiling with chloroform or ether.^ Thus, decoctions prepared by ^ The following experiments were made by G. E. Scott Smith in the author's laboratory. Fifty grammes weight of commercial black tea of medium quality was powdered and boiled with water for thirty minutes. The solution was filtered and made up to 1 litre after cooling. Aliquot parts of the solution were then treated in the following manner. A. 100 c.c. ( = 5 grammes of tea) was evaporated to a syrup and mixed with 5 grammes of ignited magnesia. The mixture was dried thoroughly at 100°, powdered, and boiled with ether free from alcohol and water. Caffeine extracted by 6 hours' treatment, „ „ 4 hours' further treatment, . II » 3 hours' „ „ Total, . 13 069 -=1-38 per cent On subsequently boiling the residue with alcohol an additional 0'0605 gramme of caffeine was extracted, making 2*59 per cent, in all. B. Was conducted like A, but dry chloroform was substituted for ether. The total caffeine extractable by chloroform was 1'54 per cent. C. Conducted like A, but rectified spirit was employed at once. It extracted 2*81 per cent, of brownish caffeine, which was reduced to 278 per cent, by re-solution in water and extraction with chloroform. D. Conducted like B, but sand was substituted for magnesia. Treatment with dry chlorofonn extracted successively 0*0365, 0-0175, 0-0135, and 0-0010 gramme of caffeine during nine hours' treatment. On subsequent treatment with alcohol much tannin and colouring matter was extracted. This was precipitated by lead acetate, and tlie concentrated filtrate shaken with chloro- form. Additional yield, O'OTO gramme, making a total yield of 277 per cent. Why a portion of the caff"eine but not the whole should be extracted by chloroform in the absence of magnesia is not evident. E. 100 c.c. ( = 5 grammes tea) was heated to boiling, treated with solid 0-059 gramme. 0-009 ,, 0-001 M EXTRACTION OF CAFFEINE. 487 boiling two separate samples of black tea with water were each divided into two equal parts. One of these was precipitated by- lead acetate, and the caffeine recovered from the filtered and con- centrated liquid by repeated agitation with chloroform. The other halves were evaporated to dryness with magnesia and the powdered residue thoroughly exhausted by boiling with chloroform, and subsequently boiled with alcohol for a long time. Sample A. 30 Minutes' Boiling. Sample B. 20 Minutes' Boiling. Lead process, Magnesia process : by chloroform, „ „ by alcohol, . 3-31 per cent. 1-18 „ 2-07 per cent. 0-90) > 2 06 per cent. lie) In other experiments with mixtures of caffeine, tea-tannin, and excess of magnesia, from 8 to 10 per cent, of the alkaloid was not extractable either by chloroform or alcohol, but could be recovered by treatment with water. 12. When finely-powdered tea is mixed with slaked lime, ignited magnesia, or sand, made into a paste with hot water, and the mixture thoroughly dried at 100°, only a fraction of the total alkaloid can be extracted with chloroform,^ however carefully the process be conducted. On subsequently treating the mixture with alcohol, the greater part of the remaining caffeine is ultimately dissolved, but prolonged treatment by boiling alcohol is necessary to extract the caffeine from a mixture of tea-extract or powdered tea with magnesia, and complete extraction is always doubtful. 13. When a decoction of tea is treated with basic or neutral acetate of lead a voluminous precipitate is formed. If an aliquot part of the liquid be filtered, concentrated, and treated with sulphuretted hydrogen, sulphurous acid, sulphuric acid, or sodium phosphate, to remove the excess of lead, and again filtered, the caffeine may be extracted in a condition of perfect whiteness and purity by agitation with chloroform. lead acetate, filtered, and an aliquot part of the filtrate concentrated, freed from lead, and shaken repeatedly with chloroform. Caffeine was recovered equivalent to 2*63 per cent, of the tea. ^ The remarkable fact of the retention of the caffeine of te* by lime or magnesia in a form incompletely dissolved by cliloroform was first observed by B. H. Paul and G. E. Sco tt Smith (Pharm. Jour., [3], xxi. 882). Little more than one-third of the total caffeine was extractable by chloroform from the lime mixture, and little more than one-half from the magnesia mixture. By subsequent treatment with alcohol the remaining catieine was dissolvsd. 488 EXTRACTION OF CAFFEINE. 14. By prolonged boiling with litharge a decoction of tea becomes completely decolorised, but the process is tedious. If after a time a small addition of lead acetate be made, clarification occurs in a few minutes, and an aliquot part of the liquid may be filtered and treated as in 13. From the foregoing statements (10, 11, 12, 13) it is evident that the determination of caffeine when in a state of solution presents no great difficulty, though the widely-used plan of evaporating the liquid with sand and lime or magnesia, and extracting the dried mixture with chloroform or ether, gives gravely inaccurate results. The great difficulty in determining the total caifeine present in tea is the obstinacy with which a portion of the alkaloid is retained by the vegetable tissue, a fact which suggests that it exists partly in some insoluble combination only gradually decomposed by boiling water or alcohol.-^ This form cannot be mere tannate of caffeine, as that compound is moderately soluble in boiling water. It is more probable that the caffeine itself is a product of the hydrolysis of a more complex body, possibly a glucoside.^ This conjecture receives considerable support from the recent experiments of E. K n e b e 1 {Apoth. Zeit.y 1892, vii. 112), who states that the caffeine in the kola-nut exists as a glucoside, k o 1 a n i n, which, on boiling with water, or treat- ment with dilute acids, splits up into caffeine, glucose, and kola- red. Ci,Hi3(0H),. On the supposition that the cellular structure of the tea is the cause of the obstinate retention of the caffeine, Z d 1 1 e r {Zeitsch. Anal. Ghem., xii. 106) has i)roposed to treat the finely-powdered tea with strong sulphuric acid diluted with one-third of its ^ The following figures, obtained in the author's laboratory, show the rate of exhaustion on treating powdered black tea with hot and cold water : — Caffeine extracted by Boiling Water. la I hour 2-46 per cent. In additional 2 hours, . 0*72 ,, „ 4 hours, . 0-16 „ „ 6 hours, . 0-01 „ Total in 12 J hours, . 3*35 * These two figures have not been transposed. Thus the extraction of the caffeine by boiling water was practically complete after 6 hours' treatment, while with cold water the total amount was not dissolved after 19 days' treatment. In both the hot and cold water experiments, the infusion reiluced Fehling'a solution after removal of the tannin by lead acetate. The caffeine did not reduce the copper solution eitlier before or after boiling with dilute acid. 2 The author has proved the presence of a glucoside in some teas. Caffeine extracted by Cold Water. n 3 days, . 1*81 per cent. dditional 2 days, . 0-29* „ „ 2 days, . . 0-70* „ 6 days, . . 0-22 ,, 6 days, . . 0-13 „ Total in 19 days, . . 3-15 DETERMINATION OF CAFFEINE. 489 measure of water, a ad heat the mixture at 100°, till the cells are thoroughly broken up. Some water is then added, an excess of hydrated oxide of lead stirred in, and the mixture dried and exhausted with alcohol of 86 per cent. The alcoholic solution is decolorised with animal charcoal, and evaporated till caffeine crystallises on cooling. From the mother-liquor, the residual caffeine is extracted by ether. Zoller obtained the high proportion of 4'92 per cent, of caffeine from a high quality of Himalayan tea, in addition to an appreciable quantity of theobromine. The author has made a number of experiments on the lines of ZoUer's process, modified in various manners, but, chiefly through the remarkable persistency with which caffeine is absorbed and retained by the carbon formed by the acid treatment, they have not hitherto resulted in the evolution of a practical analytical method.^ ^ On treating powdered tea with slightly diluted sulphuric acid, and heat- ing the mixture in the water-oven for an hour or two, a black product is obtained which powders readily. On boiling this product with water, a perfectly colourless solution is obtained, from which, after concentration, per- fectly colourless caffeine is extracted by agitation with chloroform, either with or without previous removal of the sulphuric acid by boiling with litharge or white lead, or neutralisation with ammonia. The fact that a colourless liquid is obtained on treating the charred tea with water is due to the absorption of the colouring matters by the finely-divided carbon formed. Unfortunately, this product also takes up a considerable proportion of the caffeine, and retains it with such obstinacy that it is only extracted by prolonged and repeated treatments with alcohol. Although the entire amount present is ultimately obtainable in solution, the extraction is too uncertain and tedious to render the method a desirable one in practice. Exhaustion direct with alcoliol, ether, chloroform, benzene, or water, either with or without previous neutralisation of the acid with litharge or magnesia, equally failed to ensure ready extraction. Of the numerous experiments made in this direction the following may be mentioned. Twenty-five grammes of ordinary black tea of medium quality was finely powdered, and treated with 10 c.c. of sulphuric acid diluted with one-fifth of water. The mixture was heated at 100°, treated with a little water, and ground with excess of litharge till neutral. The mixture was redried, and thoroughly exhausted successively in a Soxhlet-tube with boiling rectified spirit, boiling proof-spirit, and boiling water. The solutions were evaporated, and the caffeine extracted by repeated agitation with chloroform. The follow- ing were the results obtained: — Yield of Caffeine. By strong alcohol (sp. gr. -838), 3-03 per cent By subsequent treatment with proof-spirit, .... 0'50 „ By subsequent treatment with water, ... . 0*21 „ Total, 3-74 The caffeine isolated was snow-white. These results show that the alkaloid is unaltered by the treatment, and if extraction could be effected with certainty 490 DETERMINATION OF CAFFEINE. As the result of very numerous experiments, the author gives the preference to the following method of extracting and determining the cafifeine in tea. It closely resembles a process employed by S t a h 1- schmidt {Cheni, Gentralblat, 1861, 396): — Six grammes of finely-powdered tea is treated in a flask with 500 c.c. of water, which is then kept boiling under a reflux condenser, ^o Soxhlet extractor or similar arrangement is so eff'ective or rapid as actual boiling with the water. Alcohol effects no quicker or better extrac- tion than water, and has the disadvantage of dissolving chlorophyll. After six or eight hours' boiling, the decoction may be filtered, the residue washed on the filter, and the filtrate made up with water to 600 C.C. It is then heated nearly to boiling, and about 4 grammes of acetate of lead in powder added, a reflux condenser attached, and the liquid boiled for ten minutes. If on removing the source of heat the precipitate does not curdle and settle readily, leaving the liquid colourless, or nearly so, a further addition of lead acetate must be made and the boiling repeated. When clarification is effected, the liquid is passed through a dry filter. Five hundred c.c. of the filtrate ( = 5 grammes of tea) is then evaporated to about 50 c.c, when a little sodium phosphate is added to precipitate the remaining lead. The liquid is filtered, the precipitate washed, and the filtrate further concentrated to about 40 c.c, when the caffeine is extracted by repeated agitations with chloroform, at least four treatments with which are necessary to ensure the complete extrac- tion of the alkaloid.^ The separated chloroform solutions are mixed, and distilled in a tared flask immersed in boiling water. The last traces of chloroform are removed while the flask is still hot by a current of air, and the residual alkaloid is weighed. The caffeine thus isolated is snow-white in colour, neutral in reaction to litmus, and completely volatile and soluble in water. It does not reduce Fehling's solution either before or after boiling with dilute acid. As a precaution, the exhausted tea-powder should be again boiled with water, and the decoction treated as before. When experience has proved this to be unnecessary, the process can be shortened by boiling the tea with 600 c.c of water in the first place, and adding lead acetate without previously filtering from the exhausted tea. This modification becomes necessary in the case of by a single solvent, the process would possess marked advnntages. Substi- tution of magnesia for the oxide of lend, and various other modifications of the details equally failed to give a satisfactory result. 1 In the great majority of cases the chloroform separates readily. Should an obstinate emulsion be formed, the best plan is to place the mixture in a flask, distil off the chloroform, treat the residual liquid with a few drops of basic acetate of lead, filter, and agitate the filtrate again with chloroform. PROPORTION OF CAFFEINE IN TEA. 491 certain teas {e.g., gunpowder), the aqueous decoctions of which filter very slowly. The following results by the above process were obtained by C. M. C a i n e s in the author's laboratory (Fharm. Jour., [3], xxiii. 218). In some instances the caifeine extracted by half an hour's boiling was determined, in addition to the total amount obtained by six hours' boiling with water. The results refer to the moisture- free teas, which were represe native commercial samples : — Tannin ; by Lead Acetate. Caffeine. Description of Tea. 1 Extracted in 80 minutes. Total; extracted in 6 hours. Ceylou, whole leaf (Pelsoe), IS'Ol per cent. 3'40 per cent. 3-85 per cent. Ceylon, broken leaf, . 12-31 ... 4-03 Assam, whole leaf (Pekoe), 10-08 ... 4-02 Assam, broken leaf, . 11-33 ... 4-02 „ Java Pekoe, 12-93 ... 3-75 „ Kaisow, red leaf, 11-35 3-41 Moning, black leaf, . 11-76 3-44 3-74 Moyune Gunpowder, . 12-95 2-76 2-89 „ Natal Pekoe-Souchong, . 9-90 2-71 3-08 The foregoing process is applicable to the determination of the caffeine in coffee^ of which 12 grammes may be conveniently em- ployed. In the presence of chicory the extracted alkaloid is liable to be strongly coloured, in which case it should be redissolved in water, a few drops of caustic soda added, and the liquid again exhausted with chloroform. An alternative process for the determination of caffeine in tea is that of P a u 1 and C o w n 1 e y (Pharm. Jour., [3], xviii. 4 1 7), which in some respects resembles a method described by Versmann {Arch. Pharm., [2], Ixviii. 148), and with certain modifications com- municated to the author by A. J. C o w n 1 e y is as follows : — Five grammes weight of finely-powdered tea is well mixed in a mortar with 2 grammes of ignited magnesia, the mixture thoroughly moistened with hot water, again triturated, and then dried at 100°. It is next extracted with boiling alcohol,^ and the resultant liquid evaporated nearly to dryness. The residue is boiled with 50 c.c. of • water, and treated with a few drops of dilute sulphuric acid. When cold, the liquid is filtered and repeatedly shaken with chloroform ^ Experiments made in the author's laboratory showed that even with the most careful treatment it is difficult to ensure cmplete extraction of the caffeine, a small additional quantity being subsequently obtained by treat- ment with water. 492 PROPORTION OF CAFFEINE IN TEA. until exhausted.^ The united chloroform solution is then agitated with a very dilute solution of caustic soda, which removes a little colouring matter, so that on subsequently distilling off the chloro- form in a weighed flask, the caffeine is obtained jierfectly pure and colourless, or at most with a faint green tinge. By the foregoing process, Paul and Cownley (Pharrn. Jour., [3], xviii. 417) found Indian and Cingalese teas to contain a much larger percentage of caffeine than, owing to the faulty methods of analysis employed, is commonly supposed. The proportion of alkaloid isolated from commercial samples of all qualities, and con- taining from 3*6 to 6'8 per cent, of moisture, ranged from 322 to 4:'66 per cent, on tlie tea in its commercial condition (equal to 3*57 to 4*99 per cent, in the moisture-free tea), and bore no relation to the so-called " strength " of the tea. Java tea approached Ceylon tea in the proportion of caffeine present (294 to 3*78 per cent.), but China and Japan teas were generally poorer in alkaloid, the proportion in these products ranging (for a limited number of samples) from 2*20 to 3"46 per cent. J. H. Small obtained, by Paul and Cownley's method of assay, from 1*79 to 2 "30 per cent, of caffeine from Japanese teas, and from 2*38 to 3 "54 per cent, from Chinese and Indian teas. Paul and Cownley have also .employed the foregoing method of determining caffeine for the assay of coffee (Pharm. Jour., [3], xvii. 565, 648). The caffeine obtained by evaporation of the chloroform is liable to contain a small quantity of a brownish waxy or resinous impurity, and hence should be purified by re-solution in boiling water, and recovered by evaporating the filtered solution and drying the residual alkaloid at 100°. By this process they found the proportion of caffeine in coffee-berries to vary within comparatively narrow limits, and not to be materially affected by roasting. Hence they recommend the determination of the alkaloid in commercial coffee as a means of estimating the proportion of chicory or other admixture present. Theobromine. Dimethyl-xanthine. CyHgN.O^; or, C,-K,{CR,\-^fi,. The constitution and synthesis of theobromine have already been described (page 473). It is the lower homologue of caffeine, to which alkaloid it presents a close general resemblance, but differs considerably from it in its solubilities. 1 In Paul and Covvnley's experience, six or seven successive treatments with chloroform (using from 30 to 40 c.c. each time) are necessary to effect the complete extraction of the caffeine from the solution yielded by 5 grammes of tea. CHARACTERS OF THEOBROMINE. 493 Theobromine is isomeric with theophylline and paraxanthine. Theobromine exists naturally in cocoa, the seed or bean of Theohroma cacao ; and together with caffeine in the kola nut (StercuUa acuminata). An alkaloid apparently identical with theo- bromine was found by ZoUer in a specimen of Himalayan tea. Theobromine forms a white, crystalline powder, which under the microscope appears as trimetric needles and club-shaped groups. When heated to about 290° it sublimes without decomposition or previous fusion. Theobromine has a very bitter taste, which is only slowly developed. Its physiological action is shnilar to that of caffeine, but more powerful. In large doses it produces well-defined poisonous effects. It is eliminated by the kidneys, and can be detected in the urine. Theobromine dissolves in 1600 parts of ice-cold or 148 of boil- ing water. In cold alcohol also it is only very slightly soluble (1 in 4280), and requires fully 400 parts at the boiling-point, but dissolves far more easily in 80 per cent, spirit. It requires 1700 parts of cold or 600 of boiling ether for solution, dissolves in 105 parts of boiling chloroform, is soluble in amylic alcohol, dissolves slightly in benzene, and is insoluble in petroleum spirit. Theobromine dissolves in acids, and is precipitated from the solution by alkalies, but is soluble in excess of ammonia or fixed alkalies. It is wholly extracted from its solution in caustic soda by agitation with chloroform. Theobromine is a weak base, its salts being readily decomposed by water with separation of the alkaloid (compare Caffeine, page 482). The liydrochloride, BHCl-j-HgO, and nitrate, BHNOg, lose all their acid at 100°. B2H2PtCl6+2H20 crystallises in oblique prisms, which effloresce in the air and become anhydrous at 100°. BHAuCl^ forms tufts of yellow needles. An aqueous solution of theobromine forms with mercuric chloride a white crystalline precipitate, sparingly soluble in water and alcohol. One of the most definite and insoluble compounds of theobro- mine is that with nitrate of silver. When a very dilute aqueous solution of theobromine nitrate is treated with silver nitrate, silver-white needles containing CyHgN^Og, AgN O3 form after a short time. The compound is only sparingly soluble in water, and may be dried without change at 100°. If a solution of theobro- mine in ammonia be treated with nitrate of silver, a gelatinous precipitate is obtained which dissolves easily in warm ammonia, and on boiling the solution for some time hydrated silver theobromine, CyH^AgN^Og, separates as a granular nearly insoluble precipitate. 494 REACTIONS OF THEOBROMINE. Theobromine reacts with alkalies like a weak acid and forms definite salts. Thus the sodium salt is obtained by adding theo- bromine to soda-lye until a portion remains undissolved after long standing, and evaporating the filtrate under the air-pump. The product is destitute of crystalline structure, is extremely soluble in water, has a strong alkaline reaction, and absorbs carbon dioxide from the air. The barium salt, {C^^.j^ fi^^d^, separates on adding theobromine to baryta-water as a mass of microscopic needles, and is obtainable as a snow-white felt of silky needles by slowly cooling its solution in hot water. If the solution be rapidly cooled, it solidifies to a stiff jelly. Theobromine yields no product similar to caffeidine when boiled with concentrated baryta-water or caustic alkalies. By such treat- ment, as also when heated with hydrochloric acid under pressure to 240°, theobromine gives the same products as caffeine (page 478). The best precipitant of theobromine is a solution of sodium phosphotungstate (page 136), which should be added to a solu- tion strongly acidulated with sulphuric or nitric acid. The yellow precipitate sliould be mixed with sodium carbonate or magnesia, dried, and the mixture exhausted with chloroform, which dissolves the theobromine. When theobromine is heated with dilute sulphuric acid and lead dioxide, carbon dioxide is evolved. When once started, the reaction continues without further application of heat, and if excess of the oxidising agent and too long heating be avoided the filtered liquid is colourless, but evolves ammonia on treatment with a caustic alkali, separates sulphur from sulphuretted hydrogen, colours the skin purple-red, and immediately turns blue when treated with a moderate quantity of magnesia. Excess of magnesia destroys the colour, which may be restored by cautious addition of sulphuric acid. By oxidation with chromic acid mixture, theobromine yields carbon dioxide, methylamine, and methyl-parabanic acid, C3H(CH3)N203.-^ Aqueous chlorine converts it into methyl- urea, CH3(CH3)N20, and m e t h y 1 - a 1 1 X a n, G^{CR^l^jd^ ; while treatment with hydrochloric acid and potassium chlorate oxidises it to di m ethyl- alloxan tin, C8H4(CH3)2]S'408. Theobromine gives with oxidising agents and ammonia the same colour-reactions which characterise caffeine (page 480). Isolation and Determination of Theobromine. Theobromine may be isolated by much the same methods as those ^ Methyl-parabanic acid is easil)' soluble in hot water, from which it crystallises in transparent prisms, melting at 148°. Warmed with ammonia and calcium chloride, it gives a precipitate of calcium oxalate (compare Choles- trophane, page 481). ISOLATION OF THEOBROMINE. 495 used for the determination of caffeine, having regard to the far less ready solubility of the former alkaloid in water, alcohol, and other solvents. As in the case of caffeine, the methods used by observers who have recorded high yields of theobromine are more trust- worthy than those of chemists who have succeeded in isolating comparatively small proportions. For the preparation of theobromine, E. Schmidt (Archiv der Pharmacie, ccxxi. 656) mixes commercial cocoa (freed as far as possible from fat by pressure) with half its weight of freshly- slaked lime, and extracts the mixture with boiling alcohol of 80 per cent, (by volume). On cooling the alcoholic extract, theo- bromine separates out, and on recrystallisation from hot alcohol is obtained as a white, crystalline anhydrous product. Before extracting theobromine it is preferable to get rid of the fat by exhausting the finely-divided cocoa with petroleum spirit. The residue is made into a paste with water and ignited magnesia, dried at 100°, and exhausted with spirit of 80 per cent. Another method of extracting the theobromine from cocoa is to exhaust the substance with water or dilute alcohol, precipitate the solution with acetate of lead,^ separate the lead from the filtered solution by sulphuretted hydrogen, evaporate the filtrate to dryness, and extract the theobromine from the residue by boiling chloroform. Caffeine may be separated from theobromine by treating the mixed alkaloids with cold benzene, in Avhich theobromine is practically insoluble. James Bell {Foods, i. 85) boils 100 grains of the cocoa repeatedly with benzol, which dissolves fatty matters and caffeine.^ The residue is mixed in a mortar with 100 grains each of sand and calcined magnesia and sufficient water to form a paste, the product dried at 100"", and repeatedly boiled with strong alcohol. The solution is filtered, distilled, and the residual theobromine dried at 100° and weighed. It is freed from traces of fat and caffeine by treatment with hot benzene, and then treated twice with ^ By using a known volume of liquid and filtering off four-fifths or other known proportion, the tedious washing of the bulky lead precipitate may be avoided. When once the alkaloid is in solution, the method recommended by the author for the determination of caffeine (page 490) is also applicable to theobromine. The chloroform should be used warm. 2 Bell refers to this product, which was especially yielded by Trinidad cocoa, as a "theine-like alkaloid;" but as Weigmann and E. Schmidt have both proved the occurrence of caffeine in cocoa {Annalen, ccxvii. 306) there seems no doubt as to the nature of the substance observed by Bell. He separated it from the fatty matter by boiUng with water. The aqueous liquid was evaporated, and the alkaloid purified by successive solution in water and benzene. 496 DETERMINATION OF THEOBROMINE. a little ice-cold water. It is thus obtained white and perfectly pure, except for the presence of a trace of mineral matter.^ Bell found by this process the following proportions of alkaloid in cocoa : — Cocoa. Theobromine. Theine-lilce Alkaloid (Caffeine). Guayaquil (nibs), Grenada (nibs), Surinam (nibs), Trinidad (nibs), . Trinidad (huslcs), . 0-54 per cent. 0-91 „ 0-78 „ 0-59 „ 102 „ Trace. Trace. 02 per cent. 0-25 0-33 „ It is probable that Bell's results are considerably below the truth, since Pay en found 2 per cent.; Mi tscherlich, 15 per cent.; Trojanowski, 1-2 to 4'6 per cent.; while G. Wolfram found, in six samples of dried cocoa-beans divested of their shells, from 1*34: to 1*66 per cent, of theobromine, with an average of 1*56 per cent. The dried husks of the same beans contained from 0"42 to 1*11 per cent, of theobromine, with an average of 0*76 per cent. "Weigmann found 0*17 per cent, of caffeine in the kernel and from O'll to 0*13 per cent, in the shell of cocoa-beans. G. Wolfram {Dingl. Polyt. Joiir.^ ccxxx. 240) has described the following method of determining theobromine.^ If shelled cocoa-beans are to be analysed, they are ground up in a hot mortar to a thick paste. Ten grammes of this mass or 30 grammes weight of chocolate is digested for some time in hot water, and the solution filtered. The filtrate is precipitated with ammoniacal acetate of lead, the solution filtered hot, and the precipitate washed with boiling water till the washings (acidulated with nitric acid) cease to give a yellow precipitate with Scheibler's reagent (page 136). The filtrate is rendered slightly alkaline with soda, concentrated to about 50 c.c, strongly acidulated with sulphuric acid, and the lead sulphate separated by filtration. The filtrate is now treated with 1 This might readily be removed by dissolving the alkaloid in hot chloro- form, and such treatment would obviate the necessity of treating the impure alkaloid with water, wbich cannot be performed without loss. Bell's process is nearly identical with that previously described by T r o j a n o w s k y {Arch. Pharm., [3], x. 32 ; Jour. Chem. Soc, xxxii. 363), except for the substitution of "benzol" for petroleum ether, a change which suggests confusion between the two solvents, and probably causes loss of theobromine. 2 A similar method has been successfully employed by Mitscherlich for the isolation of theobromine from urine. DIURETIN. 497 a large excess of sodium phosphotungstate (Scheibler's reagent). The coagulation of the slimy, yellowish-white precipitate of theo- bromine phosphotungstate is facilitated by warming and stirring the mixture gently. After standing several hours, the precipitate is filtered off and washed with dilute sulphuric acid (6 to 8 per cent. H2SO4). Wolfram then decomposes the precipitate by hot baryta-water, precipitates the filtrate with sulphuric acid, removes the excess of the latter by barium carbonate, evaporates the filtered liquid, and weighs the residual theobromine, which is then ignited and any ash deducted. L. L e g 1 e r (Zeitschr. Anal. Chem.y xxiii. 89) dissolves the precipitate in caustic soda free from chlorides, nearly neutralises with sulphuric acid, evaporates to dryness with sand, and extracts the residue with amylic alcohol. The solution is evaporated to dryness at 100°, the residue weighed, and the loss of weight on ignition regarded as theobromine. A preferable plan to either would be to mix the moist theobromine phosphotung- state with sodium carbonate, dry, and extract with boiling chloroform, which on evaporation would leave the theobromine in a pure state. DiURETiN. Under this name a preparation has been intro- duced into medicine having the constitution of a combination of sodium-theobromine and sodium salicylate, and the formula C7H7XaN40,,C6H/OH).COONa. Diuretin is colourless, odourless, slightly soluble in cold water, and insoluble in chloroform or ether, but readily soluble in hot water or warm dilute alcohol. The physiological action of diuretin is said to be quite distinct from that of the analogous com- pound of caffeine. It is stated to be much more readily absorbed than simple theobromine, and to be devoid of any toxic properties, or of the peculiar excitant influence on the central nervous system exerted by caffeine. Owing to the high price of theobromine as compared with caffeine, substitution of the former by the latter alkaloid is possible, and hence G. Vulpius {Jour. Cliem. Soc.^ Iviii. 1475) has pro- posed the following method for the assay of diuretin : — 2 grammes weight of the sample is dissolved in 10 c.c. of water in a porcelain dish, the aolution acidulated with hydrochloric acid, and then rendered faintly alkaline with ammonia. The liquid is kept for three hours at the ordinary temperature, and frequently stirred. The separated theobromine is then collected on a tared filter, the filtrate being used to transfer the last portions from the dish. Gentle suction is used to remove the last of the mother-liquor, and the theobromine is th-en washed twice with 10 c.c. of cold water, dried at lOO"*, and weighed. By this method, Vulpius VOL. III. PART II. ^ I 498 THEOPHYLLINE. recovered from 41 to 41 J per cent, of theobromine from pure diuretin, 6 J per cent, remaining in the filtrate and washings. Making this allowance, the theobromine should not be less than 46 J per cent., and that isolated should melt when carefully heated, be completely volatile, and dissolve readily in caustic soda solution. From the filtrate from the theobromine, the salicylic acid can be isolated by acidulating with hydrochloric acid and agitating with chloroform. The separated chloroform is washed with water to remove mineral acid, a little water and a drop of phenolphthalein solution added, and the liquid then titrated with decinormal caustic alkali. Each c.c. of -§- alkali required for neutralisation represents 0'0138 gramme of salicylic acid. Diuretin should contain 38 J per cent, of salicylic acid. The titration completed, the chloroform may be separated and evaporated, when the residue will represent the 6 "5 per cent, of theobromine not previously separated, together with any caffeine the preparation may have contained. To prove the absence of cafi'eine in diuretin, Yulpius recommends that 1 gramme of the sample should be dissolved in 5 c.c. of water, and the solu- tion neutralised with hydrochloric acid, when the theobromine will form a milky precipitate readily soluble in soda solution. If the mixture be shaken with its own measure of chloroform, not more than 0*005 gramme of residue should remain on evaporating the separated chloroform. Theophylline, C^HglSr^Og, a base existing in minute quantity in tea, is isomeric with theobromine and paraxanthine (occurring in human urine). According to A. Kossel^ {Berichte, xxi. 2164; Pharm. Jour., [3], xix. 41; Jour. Cliem. Soc.j liv. 1115), theophylline crystallises with 1 aqua, which it loses at 110°. It melts at 264°. It is easily soluble in warm water, but spar- ingly in cold alcohol, and is extremely soluble in very dilute ammonia. It forms a crystalline hydrochloride, nitrate, chloro- ^ For its isolation, Kossel extracts tea- leaves with alcohol and evaporates the tincture to a syrup, when most of the cafleine crystallises out on cooling. The filtrate is diluted with water, acidulated with sulphuric acid, filtered after a considerable time, made alkaline with ammonia, and precipitated with nitrate of silver. After standiiij^ twenty-four hours the precipitate is filtered off and warmed with nitric acid ; on cooling the liquid, the silver nitrate compounds of adenine and hypoxanthiiu (sarcine) crystallise out. The acid filtrate is treated with ammonia, and the precipitate suspended in water acidulated with nitric acid and decomposed by sulphuretted hydrogen. On concentrating the filtrate, xantJdne first crystallises, and subsequently theo- phylline. The mother-liquor is precipitated with mercuric nitrate, the free acid being nearly neutralised with soda. The precipitate is then separated, suspended in water, and decomposed by sulphuretted hydrogen, and tht theophylline recovered from the filtrate. MANUFACTURE OF TEA. 499 platinate, auro-chloride, and mercuro-chloride, and combines with soda to form a readily soluble compound. When evaporated with chlorine-water, theophylline yields a scarlet residue, changed to violet on addition of ammonia. The silver-derivative, CyHyAgN^Og, is obtained as an amorphous precipitate on adding silver nitrate to an aqueous solution of theophylline. It crystallises from hot ammonia, and dissolves readily in nitric acid. The methyl- derivative, CyHyMeN^Og, prepared by heating the last sub- stance with methyl iodide and methyl alcohol, melts at 229**, and is identical with caffeine. Tea.^ The tea of commerce is the prepared leaf of Thea sinensis (and perhaps allied species), a shrub-like plant belonging to the genus Camellia. It occurs native in the Himalayas and Assam, has long been cultivated in China and Japan, and is now raised largely in British India, Ceylon, Brazil, &c.2 It was formerly believed that green and black teas were the product of distinct plants, but it is now known that the difference is due to the method of preparation ; black tea having undergone a certain amount of fermentation, whereas in green tea this change is carefully prevented.^ The leaves are gathered from the plants four times a year, and are distinguished according to their age. Each leaf is at first a " flowery Pekoe " leaf, which is the name applied to the leaf-bud. This becomes in succession "orange ^ French ; le Thi. German ; der Thee. 2 The Report of H. M. Customs for 1891 to 1892 states that the weight of tea imported from the peninsula of Hindostan showed a decrease of three million pounds, while that from Ceylon increased by more than sixteen millions of pounds, exceeding for the first time that of China tea, which now forms only one-fourth of our entire consumption, * " For black teas, the leaves are withered a little, rolled to Hberate the juices, left in balls for the proper state of fermentation, then sun-dried and subjected to a careful firing in a furnace. For green teas, the fresh leaves are first withered in hot pans, then rolled to free the juices, slightly roasted in the pans, sweated in bags, and returned to the pans for a final slow roasting, with stirring, for eight or nine liours, beginning at the temperature of 160° F., and falling to 120° F. at the close " ( A. B. P r e s c o 1 1 ). The methods of preparing tea vary materially in different countries. In India, the manufacturing processes are veiy much simplified, being reduced to five, instead of the twelve practised in China, In addition, the work is nearly all accomplished by machinery, so that the leaves are not touched by the labourers, except in picking. This is partially true also of Japanese tea, whereas Chinese tea is manipulated almost entirely by hand, except when the feet are employed. A detailed description of the method of preparing Japanese tea has been given by J. Takyama {Chem. News, 1. 299). 500 VARIETIES OF TEA. Pekoe," "Pekoe," "Souchong 1st," " Souchong 2nd," "Congou," and finally " Bohea."^ In some cases the leaves are classified simply as Pekoe, Souchong, and Bohea. The first and second pickings of the season furnish the finest teas ; but the quality of the product depends on the age of the tree as well as the age of the leaf ; the finest teas being produced from the young leaves of young plants, whilst old leaves, and the leaves of old wood, are deficient both in flavour and extract.^ Besides the foregoing distinctions, based on the age of the leaf, there are other classifications based on the district of growth and the method of preparation. Thus among the chief commercial varieties of hlaclc tea are Assam, Ceylon, Japan, Kaisow, Moning, and Oolong ; and those of green tea, Gunpowder, Hyson, Young Hyson, Imperial, and Twankay. Green tea has much declined in popularity of late years. " Caper tea " is always more or less of a factitious character. Very few trustworthy complete analyses of tea have been pub- lished ; and, indeed, they have but a limited interest or practical value, since the tea is not consumed as a whole, but invariably infused, and the infusion contains the tea-constituents in very difi'erent proportions from those in which they exist in the leaf. An average of sixteen analyses of tea made by K o n i g showed: — Moisture, 11*49 per cent.; caffeine, 1'35 ; albuminous ^ Pe^-Ao signifies "white hairs ;" Sou-chong, " little plant ;" and Con-gou, "labour." 2 0. Kellner {Land. Fersuchs-Stat. , 1886, 370; Jour. Ghem. Soc, Hi. 73) has published analyses of the leaves of the same tea-plant during six months (May to November). His figures show a decrease in the proportion of total nitrogen, and almost entire disappearance of amido- nitrogen in the older leaves. The cafieine fell from 2-85 to I'OO (estimated by evaporating the infusion to dryness with magnesia, and extracting with ether), and the tannin rose from 8*53 to 12 IG. The hot- water extract remained practically stationary, while the ether-extract rose from 6*48 to 22*19. The ash increased from 4 69 to 5'04 only, but in July fell to 4*29, and in September reached 5*11. All the ash determinations are improbably low, and suggest ignition at too high a temperature. Such an error would vitiate the potash determinations, which showed a variation from 49 "06 in May to 17 '31 in November. The manganese (MugOJ ranged from 1*21 to 2*48, and the chlorine from 1'04 to 1".56 per cent. of the ash. The albuminoids were determined by a modification of Stutzer's process. The aqueous decoction of 2 grammes in 100 c.c. of water was treated with 20 c.c. of a 10 percent, solution of cupric sulphate, and a titrated solution of caustic soda in such quantity as to leave a little copper in solution. The liquid filtered rapidly, and was free from albuminoids. The precipitate was washed first with hot water and then vrith strong alcohol. The contained nitrogen was determined by ignition with soda-lime. COMPOSITION OF TEA. 601 matters, 22*22; ethereal oil, ^ 067; gum and dextrin, 7*13; tannin, 12'36; fat, wax, and chlorophyll, 3*62; other nitrogen- free matters, 16'75 ; woody fibre, 20'30 ; and ash, 5'11 per cent. J. M. Eder {Dingl. Polyt Jour.^ ccxxxi. 445, 526) gives the following as the average composition of tea.^ ^1. Soluble in water— Per cent. Moisture, 10 Tannin, 100 Gallic acid, oxalic acid, and quercetin, Boheic acid, . . . , Caffeine or theine, . Tea oil, .... Albuminous bodies (probably ) legumin), . . . j Gummy substances, dextrin, and sugar. Mineral matters, . . ,1-7 0-2 01 2-0 0-6 120 3 to 4 B. Insoluble in water — Chlorophyll, . Wax, . . . . , Resin Colouring matter, . Extractive matter, mostly soluble in nitric acid, Cellulose, . . . , Albuminous bodies. Mineral matters, . Per cent. 1-8 to 2-2 . 0-2 . 3-0 . 1-8 16-0 20-0 12-7 4*0 ^ Essential Oil is determined by distilling a considerable quantity of tea (200 grammes) with 1500 c.c. of water, and agitating the distillate with ether. On distilling off the ether the tea oil remains. Eder found 0*52 per cent, of oil in gunpowder and 0'41 per cent, in pekoe bloom tea by this process. Batters hall employs 10 grammes of tea. and saturates the distillate with calcium chloride before agitating with ether. A good sample of black tea yielded 0'87 per cent, of volatile oil when examined by this method. Tea oil is a bright yellow liquid, which darkens and resinifies on exposure to the air for a few days, and turns reddish brown with nitric acid. Even on exposing the aqueous distillate from tea to the air for some time, it loses its aromatic odour, and little or no oil can then be separated from it by ether, and even if the distillate be kept iu closed vessels the aroma is soon lost. These facts explain the fact that tea leaves lose their bouquet by age or exposure. Q u e r c i t r i n and Q u e r c i t i n, stated byHlasiwetz to be present in tea, are described in Vol. III. Part I. page 341. Boheic Acid, CyHjoOg, according to Rochleder {Annalen, Ixiii. 202), exists to the extent of 0*1 to 0*2 per cent, in black tea. It is prepared by precipitating a boiling infusion of tea with acetate of lead, neutralising the filtered liquid with ammonia, suspending the washed precipitate in absolute alcohol, and decomposing it by sulphuretted hydrogen. The filtrate is evaporated to diyness m vacuo, and the residual l)oheic acid purified by resolution iu water, &c. It is a yellow resinous body, melting at 100° to a tenacious manner, and decomposed on exposure to air. It is extremely soluble in water and a^.cohol, and giving a brown coloration but no precipitate with ferric chloride. The salts are mostly insoluble and amorphous. ^ Eder's figures for mineral matters soluble in water are considerably lower than any other observer, and his proportion of insoluble matters is in excess and of soluble in deficiency of those usually recorded. His tannin, which was 502 JAPANESE TEA. The following analyses by Y. K o z a i {Bulletin, No. 7, Imperial College of Agriculture, Japan) have a special value owing to the author's knowledge of tea manufacture. Special precautions were taken in sampling the leaves to ensure strictly parallel specimens being taken. The figures refer to the moisture-free leaves in each case : — Unprepared Leaves. Green Tea. Black Tea. Caflfeine or theine, Ether-extract, Hot-water extract, Tannin (as gallotannic acid), , Other nitrogen-free extract, Crude protein, Crude fibre Ash Albuminoid nitrogen, Caflfeine nitrogen, .--. .... Amido-nitrogen, Total nitrogen, S-30 6-49 50-97 12-91 27-80 37-33 10-44 4-97 4-11 0-96 0-91 5-97 3-20 5'52 53-74 10-64 31-43 37-43 10-06 4-92 3-94 0-93 113 5-99 3-30 5-82 47-23 4-89 35-39 38-90 10-07 4-93 4-11 0-96 1-16 6-22 The proportion of ash found by Kozai is remarkably low, but it seems not impossible that this is characteristic of Japanese teas, since some analyses byj. Takayama {CJiem. Neivs,\. 299) show the same peculiarity. An analysis of the so-called " flower of tea," consisting of the hairs of the leaf-buds of the tea-plant, has been published by T. B. Groves {Tear-Book Pharm., 1876, page 610). James Bell {Foods, i. 6) gives the following figures as illustrating the composition of fair representatives of black and green teas of commerce :^ — determined by precipitation with cupric acetate, is unusually low. Of the extract, from 15 to 16 per cent, was precipi table by strong alcohol. A nitrogen determination on the precipitate gave a result corresponding to about 12 per cent, of albuminous matters, and the difference was regarded as gummy sub- stances. The chlorophyll, wax, and resin were extracted by ether from the insoluble matter, after drying, and the residual cellulose purified by treatment with nitric acid, potash, and alcohol. ^ It is evident that in these analyses some constituent was determined by difference, but it is not stated which. Nor does Bell state the method used for determining the tannin, the figures for which are highly improbable, ivhile other of his descriptions are incomplete or obscure. COMPOSITION OF TEA. 503 Moisture, Caffeine, . Albumin, insoluble Albumin, soluble, Extractive by alcohol, containing nitrogenous matter, . Dextrin or gum, Pectin and pectic acid, Tannin, .... Chlorophyll and resin, Cellulose and insoluble colouring matter, Ash, Conejou (Black). 8-20 3-24 17-20 •70 6-79 2-60 16-40 4-60 34-00 6-27 100-00 Young Hyson (Green). 5-96 2-33 16-83 -80 7-05 •50 3-22 27-14 4^20 25-90 6-07 100-00 The following figures are given by J. P. Battershall {Food Adulteration, page 28) as the results of the analysis by American chemists of samples representing 2414 packages of Indian tea, a class remarkable for their general strength, high quality, and freedom from adulteration : — Minimum. Maximum. Average. Moisture, 5-83 per cent. 6-32 per cent. 5-94 per cent. Insoluble leaf, . 47-12 „ 55-87 „ 51 •91 Extract, 37-80 „ 13-04 40-35 „ 18-87 „ 38^84 „ 15-32 Tannin, Caffeine or theine, . 1-88 3-24 2-74 Ash:— Total, . . 5-05 6-02 5-61 „ Soluble in water. 3-12 „ 4-28 „ 3-52 Insoluble in acid. 0-12 0-30 „ 0-18 „ The following figures, obtained by C. M. C a i n e s in the author's laboratory, are interesting as indicating the character of the first parcel of Natal tea ever imported into England :^ — Moisture, 8*36 ^ Natal tea must not be mistaken for the so-called "Cape tea" and "Bush tea," consisting of the dried leaves and Iwigs of certain species of Cyclopia. According to H. G. Greenish {Pharm. Jour.,\Z'], xi. 549, 569, 832), Cape tea is destitute of caffeine or other alkaloid, but contains a 604 CAFFEINE IN TEA. per cent. ; insoluble matter, 51-96 ; hot-water extract (complete), 39-68; tannin by PbAg, 8-33; tannin by CuA^, S'SO; caffeine by Pblg and chloroform, 2*85; total ash, 6-14; soluble asli, 3*56 ; alkalinity (K2O) of soluble ash, 1*15 per cent. Tlie Moisture contained in commercial tea varies within some- what wide limits (4-2 to 10-8 per cent.); but the range is far less when teas of the same class are compared. Thus G. W. W i g n e r (Pharm. Jour., [3], vi. 361) found that hyson and gunpowders, both of which are highly-dried teas, contained the smallest proportions of moisture (4-84 to 6*55 per cent.), and, after drying at 100°, absorbed from 6*04 to 6-98 per cent, of water on exposure to air. Congou teas showed in their original condition an average of 8-50 per cent, of moisture, and never wholly regained their original weight on exposure to air after drying at 100°. The average pro- portion of moisture in commercial tea is about 7-7 per cent., and the usual range between 7 and 9 per cent. Caffeine or Theine. The proportion of alkaloid present in tea varies considerably, the general range being from 3-0 to 4-0 per cent. ; but the experiments of Paul and Cownley (page 492) show that in Indian and Ceylon tea the proportion is more frequently above 4 per cent, than below that figure ; and in a special sample of Himalayan tea, Zoller found as much as 4*94 per cent, of caffeine, in addition to a small proportion of what was apparently theobromine. Unfortunately, by far the greater number of published determina- tions of caffeine are quite unreliable (see page 484), and, indeed, the low figures recorded suffice to indicate their inaccuracy ; and hence any deductions as to the relation of the quality of tea to the proportion of alkaloid present must be received with great caution. The proportion of caffeine is not generally considered to have any direct relation to the commercial value of the tea, and the tea-taster takes no cognisance of it. The results of J. F. Geisler (page 506) tend to show that the proportion of caffeine which passes into the infusion has a relation to the quality of the tea, the superior qualities giving up their alkaloid to water more perfectly than the inferior ; but as the whole of Geisler's figures for caffeine (1*15 to 3-50 per cent.) are probably below the truth, too glucosidal body called cyclopin, CgsHasO^s, similar to cinchona- iiovatannic acid, and yielding, when boiled with dilute acid, glucose, and a substance of the formula CigHgaOjo, closely resembling cinchona-uova- icd. Greenish also found a crystalline substance exhibiting a green fluorescence in alkaline solutions, and probably identical with the cyclopic acid j'feviously described by A. H. Church {Chem. News, xxii. 2); and like- wise a third substance analogous to cyclopin, and apparently an oxidation- product of that body. Cape tea yielded the author 30 per cent, of extract, and on ignition left 3 '7 per cent, of an ash containing manganese. EXTRACTIVE MATTER OF TEA. o05 iimch stress must not be laid on this conclusion;^ and the same remark is applicable to the proposition of P. D v o r k o v i t c h, that tlie higher the proportion of alkaloid bears to that of the tannin and fermentation-products, the more valuable is the tea. This varied from 16"0 : 84 to 24'5 :75*5, the percentage of alkaloid in the tea itself ranging from 2*14 to 3'45 per cent. Chlorophyll. When either green or black tea is boiled with alcohol or chloroform a solution of a more or less grass-green colour is obtained, owing to the extraction of chlorophyll. E. B. K e n r i c k states that cheap black teas yield less chlorophyll than the better kinds, and believes that a distinction of practical value might probably be based on a colorimetric determination. Extract. By the term " extract," when used in reference to tea analysis, is understood the sum of the soluble matters extracted from the leaf by boiling water. It includes caffeine, tannin, albuminous matters, gum, dextrin, colouring matter, mineral matter, &c., besides other less important constituents, such as gallic acid, boheic acid, oxalic acid, and quercetin, which substances are present in comparative small quantity, if at all. The proportion of extractive matter yielded necessarily varies with the method used to exhaust the tea, and is, of course, higher when the tea is powdered and the treatment with water long con- tinued and carried to an extreme than when the whole leaves are used and the tea simply infused in boiling water. The latter method commends itself when the object is to study the character of the infusion likely to be yielded in practice, while the former plan gives more information when the objection is the detection of adulteration. An interesting com|)arison of the results of the two methods has been made by J. F. G e i s 1 e r, who has published an extensive series of analyses of teas obtained direct from American importers and w^holesale houses {American Grocer , Oct. 23, 1884; Analyst ix. 220 ; Prescott's Organic Analysis, page 505 et seq.). The following table by Geisler shows the proportions of extract, tannin, caffeine, and ash which passed into solution when various repre- sentative commercial teas were infused under precisely the same conditions by pouring on the leaves 100 times their weight of boiling distilled water, and allowing the liquor to " draw " for ten minutes. The ratio which the dissolved constituent bore to the total is also given. 1 In a private communication to the author, Mr Geisler states that the catfeine was determined by mixing the concentrated decoction with magnesia and sand, and exhausting the dry mixture with chloroform (compare page 486). 606 INFUSION OF TEA. Extract. Tannin.2 Caf- feine. Ash. Kind of Tea. Wholesale Price per lb. in Cents. Infu- Ratio to Total. Infu- Ratio to Total. Infu- sion. I'otaL sion. sion. sion. Fine Ceylon Pekoe tips.i . 33-25 76-6 17-19 75-3 2-44 3-44 91-0 Assam, m 29-15 73-5 11-48 60-8 3-30 3-80 70-0 Assam, 22t 28-57 72-0 9-50 58-4 2-75 4-40 79-5 Finest Moyune Gunpowder, 75 37-32 73-2 16-79 87-8 2-95 4-60 55-8 Common Moyune Gun- \ powder, ... J Japan Basket-fired, 18 28-07 79-4 9-26 77-7 1-67 4-02 66-1 31-75 75-6 11-23 74-5 2-17 4-27 80-8 Japan Pan-fired, . 34-37 79-6 13-41 94-4 2-07 3-67 63-6 Choicest Formosa Oolong, . 65 33-62 75-9 12-91 75-6 2-50 4-00 71-3 Choicest Formosa Oolong, . 53 33-30 73-7 13-75 68-5 2-42 3-97 66-5 Superior Formosa Oi^loiig, . 30 29-00 68-6 9-63 59-6 2-12 3-66 62-3 Medium Am oy Oolong, 24 27-40 60-9 1012 56-0 1-92 3-72 68-5 Medium Amoy Oolong, 215 24-50 60-5 7-53 55-6 1-70 3-25 58-9 Choicest Moning Congou, . 45 24-25 70-6 5-46 41-7 2-87 4-13 73-7 Superior Moning Congou, . 27 21-55 57-8 4-44 32 2-77 3-70 63-6 Medium Moning Congou, . m 21-02 68-6 5-55 45-2 2-33 3-22 58-3 Good Common Kaisow Con- \ gou, . . - / 17i 23-25 64-1 4 05 38-5 2-35 3-30 59-9 Common Moning Congou, 15J 19-50 72-2 4-50 52-9 1-95 2-88 46-8 1 Jour. American Cltem. Soc, xiii., Ho. 8. 2 The determinations of tannin were made by the Lowenthal method, except in a few nstances in which the cupric acetate method was employed. 8 This sample is considered by Geisler to have been adulterated, though its appearance did not indicate any admixture with exhausted leaves.— (Private Communication to Author.) A comparison of these figures shows that, as a rule, the finer teas yield to hot water larger proportions of extract, caffeine, and ash than the inferior qualities. On an average, the ash of the extract exceeds by 0'62 per cent, the "soluble ash" obtained by treating the ash of the entire tea with water. The proportion of tannin rises and falls with that of the extract, and the ratio which the dissolved extract and tannin bear to the total has a notable relation to the price of the tea. By the same method of 10 minutes infusion in boiling-hot water, E. B. Ken rick (Bulletin No. 24, Laboratory of Inland Revenue Department, Canada) obtained the following average results from commercial samples of tea : — Description of Teas. No. of Samples. Aqueous Extract. Tannin Dissolved, Caffeine Dissolved. Ratio of Aq. Extract to Tannin. Congou, Assam, Ceylon, Unclassed Black, Japan, Gunpowder, Young Hyson, . 10 3 2 13 18 2 5 23-37 38-53 27-45 23-76 30-07 28-55 34-22 5-18 7-49 7-85 5-40 9-38 8 '00 10-98 2-65 2-98 2-68 2-82 2-45 2-39 2-52 4-51 3-81 3-50 4-40 8-20 3-57 3-12 INFUSION OF T'EA. 507 From these figures it appears that congou teas yield less extract than green and Japan teas, while Assam and Ceylon teas yield intermediate results. Not only do the Japan and green teas yield more soluble tannin than the black, but the proportion of tannin to the whole extract is greater in the former kinds. On the other hand, the black teas appear to yield more soluble caffeine than the Japan and green teas. The following figures by G e i s 1 e r show the influence of the time allowed for infusion upon the proportion of the constituents dissolved, and the difference in the result caused by substituting New York water (Croton River, of 4*96 degrees hardness per 100,000) for distilled water. In each case the tea used was the finest Formosa Oolong, and it was infused in 100 parts of boiling water: — Distilled Water. Croton Water. 3 min. 5 min. 10 min. 1 hour. 5 min. 10 min. Total extract, 25-97 28-37 30-87 33-75 27-47 30-25 Ash 3-72 3-80 4 17 4-33 3-62 4-13 Extract minus ash, . , 22 25 24-50 26-70 29-42 23-85 26-12 Tannin 9-75 11-23 13-46 14-94 10-18 10-60 Caffeine, 1-95 2 65 2 75 2-85 2-02 2-82 Alkalinity of infusion-ash (= K2O), 103 1-08 1-22 1-28 1-08 1-15 From these results it appears that infusion in distilled water for 3 minutes is insufficient, but in 5 minutes practically as good a result is obtained as in a longer time, without so much astringent matter being extracted. ^^Hien Croton water is used, 10 minutes gives a materially better result, so far as caffeine and extract are concerned, while the proportion of tannin is not increased in the same proportion. In all these experiments the volatile oil is left out of consideration, though it is to this constituent that the flavour and aroma of the tea is due, and on these characters the commercial value of the tea materially depends. The tannin and extractive matter impart astringency, strength, and body to the infusion. Caffeine, being almost tasteless, is not taken into account by tea- tasters, though physiologically it is the most important constituent of tea. In tasting tea, it is usual to infuse the weight of a sixpenny piece (43 grains) of the sample in 3 J fluid ounces of boiling water, and to pour off the infusion after standing from 3 to 5 minutes, according to the practice of the taster. The infusion is not 508 TEA-TASTING. swallowed, arid, of course, no sugar or milk is added. In the process of manufacture, the different sized leaves are separated by sifting, and thus broken leaves and dust are obtained, which, though yielding a strong infusion, will be sold at a lower rate. Broken or powdered tea loses its aroma more rapidly than whole- leaf tea. Hence, in judging of the commercial value of a tea, the appearance of the leaf and extent to which it is damaged are taken into account as well as the characters of the infusion. The infusion is judged by its strength or astringency, its flavour, its colour, and its odour. The strength and flavour are dependent on the age, and consequently the size of the leaf, and the time the tea has been kept since its manufacture. A chemical analysis will indicate the strength, but not the flavour of the infusion, and hence is of little use in the valuation of high-priced teas ; but as in medium and low-priced teas the strength is of as great or more importance than the flavour, a chemical analysis will, in such cases, go far to indicate the commercial value of the tea. The opinion formed of a tea by a professional taster is sometimes very dijfferent from that to which a chemical examination would lead.^ It is comparatively unusual for unmixed tea of any kind to be sold retail. Blending of several kinds is very generally practised, and when conducted judiciously materially improves the character of the tea. ^ In 1874, the author submitted to two tea-tasters of considerable experience a series of samples which he had specially prepared to test their ability to recognise adulterations of tea by the taste. The following were the opinions expressed : — Nature of Sample. A ' s Opinion. B ' s Opinion. No. 1. 70 per cent, of No. 2 and 30 per cent, exhausted and redried leaves. Tasted "washed-out ; " no doubt from presence of exhausted leaves. Very poor ; contained many exhausted leaves : ranked fifth. No. 2. Genuine black tea of fair quality. Genuine. Passed pure ; ranked first No. 3. No. 2 somewhat crushed. No. 4. 80 per cent, of No. 2 and 20 per cent, of ex- hausted leaves, to which a little NaaCOa was added while redrying. Mixed with exhausted leaves. Genuine ; better tea than No. 3. Would have been the best, but lacks strength, and is therefore suggestive of exhausted leaves. Ranked third. Not pure, but very slightly adulterated with ex- hausted leaves. Ranked fourth. No. 5. 80 per cent, of No. 2, 20 per cent of exhausted leaves, and a little cate- chu. A washed-out tea to which some astringent matter had been added. Passed pure, and ranked second. ADULTERANTS OF TEA. 609 Adulterations of Tea. Before the passing of the Adulteration of Food Act of 1872, tea was subject to adulterations of the grossest kind,^ most of which were practised prior to importation. By the Sale of Food and Drugs Act of 1875, provision was made for the examination of tea by the Custom House, and the exportation or destruction of very bad paicels.2 Hence the tea now sold in the United Kingdom is rarely adulterated in the gross manner which was formerly common.^ The adulterants of tea may be conveniently arranged under the following four heads : — 1. Mineral additions used for increasing weight or bulk; such as sand, magnetic iron ore, brass filings. 2. Organic additions used for increasing weight or bulk ; such as previously infused leaves, and leaves other than those of the tea plant, as slow, elder, willow, &c. 3. Adulterants used for im^ parting fictitious strength, by increasing the astringency or deepen- ing the colour of the infusion ; as catechu, sodium carbonate, borax. 4. Facings and colouring materials ; as steatite, prussian blue, indigo, turmeric, graphite, &c. The practice of facing tea, formerly very common, is now con- fined to certain kinds of green tea, especially gunpowder, and the ^ By section 5 of 11 George I. cap. 30, the adulteration of tea by terra japonica (catechu), leaves other than leaves of tea, or any other ingredients whatever, was punishable by forfeiture and a fine of £100. By section 11 of 4 George H. cap. 14, a penalty of £10 was imposed for the sale of every pound of tea which was mixed, coloured, stained, or dyed with terra japonica, sugar, molasses, clay, logwood, or with any other ingredients or materials whatsoever. 2 On May 9, 1891, W. Cobden Samuel, the chief chemist in the Custom House Laboratory, reported that 437 samples had been analysed during the year 1890, viz.: — 84 samples green faced tea; 10 green not-faced tea; 96 green caper tea ; 154 black congou tea ; 64 black dust tea ; and 29 samples of siftings. Of these, 384 samples were found on analysis to be satisfactory. Of the remain- ing 53 samples, representing 516 packages of doubtful and unsound teas, 1 sample, representing 5 packages, was admitted to home consumption ; 41 samples, representing 301 packages, were restricted to exportation, owing to the presence of exhausted leaves, damage, or other causes within the Act ; 8 samples, representing 139 packages, were refused admission, as unfit for human food ; and 3 samples, representing 71 packages, were on analysis found to be teas that had previously been imported, and ordered to be exported. They were this year reimported and relabelled as new season's teas. This fact, with the analysis, was reported to the Boanl of Customs, and the whole of the parcel of 71 packages was ordered to be seized under the Merchandise Marks Act. ^ This statement does not apply to all countries. As recently as 1888, Wend a and Wiorogorski described various adulterations they had met with in tea sold in Warsiiw. Bukowski and Aleksandrow in the same year found as much as 40 per cent, of ash in tea, and a considerable proportion of brass-filings in one sample. 610 MINERAL ADULTERANTS OF TEA. mineral additions for increasing weight or bulk no longer include (so far as the United Kingdom is concerned) considerable pro- portions of magnetic iron ore, &c., as was formerly the case. For the detection of mineral adulterants, and to obtain certain other knowledge, the tea should be ignited, and the proportions of ash soluble in water and acid determined. In practice this is best effected by igniting 6 grammes of the tea, in its ordinary com- mercial condition, in platinum, at as low a temperature as possible. When the carbon is burnt off, the ash will have a distinct green colour, owing to the formation of manganate. The ash is weighed and boiled with water, the solution filtered, and the residue washed, ignited, moistened with ammonium carbonate, very gently ignited, and weighed. The difference between the weight now found and that of the total ash gives that of the ash soluble in water?- The insoluble ash is next boiled with strong hydrochloric acid, the solution diluted with hot water, filtered, and tlie insoluble residue washed, ignited, and weighed. It consists of extraneous siliceous matter, such as sand, fragments of quartz, &c., and in- soluble silicates, such as steatite from the facing of gunpowder tea. If titanic iron sand be present, some of it will almost certainly remain undissolved, and present the appearance of jet-black magnetic particles.^ The solution of the ash soluble in water should be titrated with ^ If prefeiTed, the weight of the soluble ash can be ascertained directly, by evaporating the solution and weighing the residue. 2 The adulteration of tea with magnetic matter, formerly (in the experience of the author) very common, is now apparently nearly obsolete, a clear proof that the mineral admixtures were not due to accidental causes. Magnetic matter is best detected by reducing 10 grammes of the tea to powder and spreading it in a thin layer on a sheet of smooth paper. A magnet or electro-magnet is then applied to the under-side of the paper and moved laterally, with its poles in contact with the paper. Any magnetic matter may thus be readily drawn out and separated from the tea. It is next boiled with water for a few minutes to detach adherent organic particles, and the water decanted. The residue is then dried and weighed, and examined under the microscope as an opaque object. If it consists of magnetic oxide or titanate of iron, crystalline facets will probably be apparent, the bulk of the object having a jet-black colour. Metallic iron would be distinguished from the foregoing ferruginous minerals by its solubility in moderately strong nitric acid (sp. gr. 1 -2) with evolution of red fumes, and by its precipitating metallic copper from a warm and slightly acidulated solution of cupric sulphate. The weighing of the matter actually extracted by a magnet is far more satisfactory than the estimation of the iron existing in the tea. Tea naturally contains a small proportion of iron, but it only amounts to about 3 per cent, of the weight of the ash, or about 018 per cent, of the entire tea. Of course the iron in this form is not affected by a magnet, the use of which has the ASH OF TEA. 611 methyl-orange or litmus and standard acid, the volume used being calculated to its equivalent of potassium oxide (1 c.c. of j^ acid = 0-00471 gramme of KgO). The analyses of a very large number of teas show that the pro- portion of soluble ash and its alkalinity vary with the age of the leaves, the figures yielded being highest with young leaves and teas of high quality. The total ash of absolutely pure tea rarely, if ever, exceeds 6 per cent., but some licence must be allowed in dealing with commercial samples. Hence in 1874, the Society of Public Analysts suggested 8 per cent, as the maximum limit of total ash allowable in tea, of which not less than 3 per cent, should be soluble in water. These figures refer to tea previously dried at 100°, and as the proportion of water usually lies between 7 and 8 per cent., the corresponding limits for tea in its ordinary com- mercial condition will be 7 '40 and 2'77 per cent, respectively. Somewhat more recently (1875), G. W. Wigner {Pharm, Jour., [3], vi. 262, 281) obtained the following average results by the analysis of sixty-seven samples of commercial tea taken from the original chests. The samples embraced forty-one of ordinary character, eighteen special teas of high price, and nine samples of caper. Wigner regarded and described these last as "genuine," and they were clearly free from any large proportion of mineral adulterants, but the author strongly questions whether any specimen whatever of caper tea really deserves the description of " genuine." Results of Analysis of Ash. Total. Siliceous Matter. Soluble in Water. Alkalinity as K2O. Samples in Commercial State— Maximum, . . . . Minimum, Average Samples after drying at 100° C- Maximum Minimum, . . . . Average 7-02 5-17 5-78 7-42 5-57 6-33 1-67 0-04 0-46 1-76 0-04 0-50 3-88 2-64 3-15 4-16 2-94 3-45 1-96 1-08 1-45 2-11 1-26 1-54 advantage of extracting the iron in the form in which it actually exists, and production in court if necessary. In 1873 and 1874 the author frequently found from 5 to 8 per cent, of magnetic matter in caper tea, and at that time the use of the magnet for its detection v^as well known to, and habitually practised by, the trade. 512 ASH OF TEA. The asli of these sixty-seven samples of tea had the following average composition : — Including Silica, &c. Exclusive of Silica, .fee. Siliceous matter Soluble in acid, Soluble in water, 7-96 per ceut. 37-54 54-50 ... per cent. 40-79 „ 59-21 „ 100-00 per cent. 100-00 per cent. Alkalinity of soluble ash, as K2O, . 25-09 per cent. 27-26 per cent. James Bell {Foods, i. 29, 31) has published figures agreeing with those of Wigner. The proportion of soluble ash in genuine teas analysed by Bell ranged from 2*8 to 4*2 per cent, (calculated on the moisture-free tea), the proportion being usually between 3*2 and 3 '6 per cent. In one instance only did the solubie ash fall below 3 per cent., and in that case the deficiency was very trifling, the proportion being 2 "9 7 per cent. The alkalinity of the soluble ash of the teas examined by Bell ranged from 1*30 to 1'91 per cent, of KgO. In only one case did the total ash reach 8 per cent., while the insoluble siliceous matter exceeded 1 per cent, in a few instances only. Bell's results are fairly in accordance with the wide experience of the author (see Chem. News, xxix. 167, 189, 221).^ ^ The following results of partial analyses of average samples of commercial black teas, as ordinarily imported, have been communicated to the author by M. J. Sheridan, Assistant Chemist in H.M. Customs Laboratory. The figures refer to the undried tea : — Ash. Description of Tea. Extract ; on Whole Leaves. TotaL Soluble in Water. Siliceous Matter. Indian :— Orange Pekoe, , 5-40 8-20 0-45 40-49 Assam Pekoe, . 6-10 3-30 0-90 39-32 Souchong, 5-70 3-15 0-60 39-44 Pekoe Souchong, 5-75 3-25 0-70 38-78 CETLON :— Broken Orange Pekoe, . 5-50 3-20 0-20 42-90 Ceylon Pekoe, . 5-40 3-35 0-25 38-24 Souchong, 5-60 3-40 0-30 37-98 Japan :— Sittings, 6-12 3-15 0-95 29-80 Java :— Congou, .... 5-00 3 05 0-50 34-60 Congou, . 7-65 3-75 1-05 30-72 China :— Kaisow Congou, 5-70 3-25 0-50 32-95 Common Congou, . 5-85 2-95 1-00 31-71 Souchong, 5-60 3-05 0-65 33-57 Oolong, .... 5-65 3-20 0-70 34-10 Flowery Pekoe, 5-45 3 05 0-55 35-70 Port Natal :— Congou, .... 5-65 3-10 0-45 34-80 EXHAUSTED TEA LEAVES. 513 In certain cases a high sokible ash does not indicate a high quality of tea. This liappens when the ash contains a notable pro^ portion of sodium chloride, owing to the tea having been damaged by sea-water and redried. The ash of pure tea contains only a trifling proportion of sodium, less than 2 per cent., and the chlorine does not exceed 1*1 per cent., equivalent to about 1'8 of sodium chloride, representing 0"108 per cent, of the weight of the tea. Wigner (Pharm. Jour., [3], vi. 403) found 3-08 per cent, of sodium chloride in tea which had been a fortnight under sea-wnter and completely soaked, and 0'17 and 0'23 in samples which had been slightly moistened. treviuu6lij infused or exhausted leaves are among the adultera- tions of tea most difficult to detect, especially when present only in moderate proportion. The sophistication of tea in this manner was formerly extensively practised in England, the exhausted leaves being treated with gum or other matters, and rolled and redried so as to resemble genuine tea.^ The treatment of tea with hot water necessarily results in the removal of certain of the ash-constituents, especially the potassium salts of organic acids. Hence the exhausted leaves will contain a smaller proportion of total ash, and especially of ash soluble in water. Tlie extent of the change produced by infusion will, of course, depend on the perfection of the exhaustion. The author found in a mixture of infused leaves from various teas 4*30 of total ash, of which 0*52 per cent, was soluble in water. James Bell {Analysis and. Adulteration of Foods, i. 29) gives the follow- ing figures obtained by the analysis of the ash of tea-leaves which had been infused in the ordinary way for domestic use, and after- wards redried at 100° : — Description of Tea. r Ash of Sample. Total. Siliceous Soluble in Matters. Water. Alkalinity, as K2O. Congou, . Moning, . Orange Pekoe, . Hyson, Souchong, . 3-92 4-53 3-77 5-56 4 12 0-41 0-95 0-57 1-40 0-70 0-54 0-85 0-68 0-76 0-81 0-11 0-28 018 0-21 0-19 ^ Though less extensively carried on than formerly, the practice of redrying infused tea-leaves is not obsolete. The infused tea-leaves from the various bread and kindred shops, now so numerous in London, are regularly VOL. III. PART II. 2 K 614 EXTRACT OF TEA. The total ash of the foregoing samples averages 4*38, and the soluble ash 0'73 per cent. Exhausted tea-leaves are also indicated by the deficient extract (and consequently liigh insoluble matter) and low proportion of tannin.^ As already stated, the yield of extract depends materi- ally on the condition of the tea, more complete extraction of the soluble matters being effected when the powdered tea is used than when the exhaustion is effected on the leaves in their commer- cial condition. For the purpose of detecting adulteration, the powdered tea should always be used, or the results will not be fairly comparable. The determination of the total extract and insoluble matter of tea is best effected by boiling 2 grammes of the tea in a state of powder with 100 C.C. of water for one hour. The liquid is filtered while hot, the residue boiled again with 50 c.c. of water, and the process repeated as long as colouring matter continues to be extracted, the liquid being poured through the filter previously used.^ After cooling, the decoction is made up to 250 cc, or other convenient measure, and an aliquot part (one-fifth) evaporated to dryness for the determination of the extract. The filter and its contents should be dried at 100°, and the insoluble matter detached and weighed. Very constant results are thus obtainable. The minimum proportion of extract yielded by genuine tea exhausted in a state of powder was fixed by the Society of Public Analysts in 1874 at 30 per cent. Assuming the presence of 7 '5 per cent, of moisture, this leaves 62 per cent, for the maximum proportion of insoluble matter. This figure covers almost all legiti- mate variations in tea, and is considerably in excess of the propor- tion yielded by green tea, the insoluble matter from which averages 42 per cent., while in black teas the average is only about 50 per bought up and redried ; and the leaves of the tea infused by tea-tasters are systematically preserved and sold for the same purpose. ^ J. M. Eder obtained the folloviring figures by the analysis of teas adul- terated with exhausted leaves purchased in small shops in the suburbs of Vienna : — Tannin (by Cul^)- Extract. Total Ash. Soluble Ash. Riissian tea, . Bloom tea, . . Bloom tea, . . 6-60 4-91 5-13 18-4 15-3 14-6 4-76 S-34 4-51 0-85 0-54 0-90 * The decoction of some teas filters very slowly, and it is necessary to strain the liquid through fine muslin instead of filtering it through paper. EXTRACT OF TEA. ,515 cent. In the case of old-leaf Congou teas containing much stalk, and which have been stored for some time, the extract may occa- sionally fall to 30 per cent., corresponding to 62 J per cent, of insoluble matter. In judging a tea by the proportion of extract or insoluble matter, it is very desirable, when possible, to take into account the character of the sample. Thus young leaves (which are to some extent indicated by their size) yield a notably higher extract than fully grown or old leaves, or specimens containing a considerable proportion of stalk. G. W. Wign e r has recorded the proportions of extract yielded by a sample of tea in powder when boiled with different quantities of water. In each case the tea was boiled with the water under a reflux condenser for one hour, the decoction cooled, filtered, and evaporated to dryness. A. 1 part of tea in 200 parts of water yielded .54 10 ; er cent, of extract. B. .. ,. 100 ,, ,, 30-55 „ „ C. „ .. 50 „ ,, 27-55 „ „ D. „ „ 20 „ „ 22-90 ■ £. Exhausted leaves from expt. D in 20 \ j,.,.. parts water, . . . it 3-75 I 1.75 j 36-67 F. .. ., E G. „ „ F Even after four boilings with 20 parts of water, the tea was not completely exhausted. Hence Wigner preferred to determine the extract by boiling the powdered tea once, for one hour, with 100 parts of water, instead of repeatedly exhausting with smaller quan- tities. Operating in this manner he obtained proportions of extract ranging from 26*15 to 44*85 per cent., the average being 35*70 per cent., containing 46 3 of ash.^ The determination of tannin in tea affords valuable information respecting the probable presence of previously infused leaves or extraneous tannin matters, such as catechu. This is best effected in the aqueous decoction obtained by exhausting the sample with boiling water, as required for the determination of the extract. The tannin may be estimated by H. R. Procter's modification of Ldwenthal's process, as described in Vol. III. Part I. page 110. A volume of the above decoction, corresponding to 0*04 gramme of tea, may be taken for the original titration with perman- ganate j and of the decoction deprived of tannin a volume correspond- ^ The ash of the soluble extract of tea always exceeds by a considerable amount the proportion of tea-ash soluble in water, doubtless owing to the presence in tea of soluble salts of calcium and magnesium with organic acids, which salts on ignition are converted into calcium carbonate and magnesia, and thus become insoluble in water. 516 FERMENTATION PRODUCTS IN TEA. ing to 0"080 gramme of tea. The tannin of tea is stated by some chemists to be gallotannic acid, and by others to be identical with that of oak-bark. The reduction-equivalent of the latter is almost identical with that of crystallised oxalic acid, so that the weight of this substance corresponding to the volume of permanganate decolorised gives without calculation that of the tannin present. The process of fermentation to which black tea has been sub- jected undoubtedly causes modification of the tannin, with forma- tion of dark-coloured insoluble matter. The author found that a tincture of green tea precipitated tincture of ferric chloride bluish black, like nut-galls, while the tincture of black tea gave a green colour with iron, just as catechu does. A modification of the permanganate process, which appears to possess some advantages for the examination of tea, has been described by P. Dvorkovitch {Ber., xxiv. 1945 ; Jour. Cliem. Soc, Ix. 1302), who aims not only in estimating the tannin but also the proportion of fermentation-products formed in the process of fermentation to which l)lack tea has been subjected. For this purpose he treats 10 grammes of finely-powdered tea with three successive quantities of 200 c.c. of boiling water, five minutes being allowed for each digestion. The residue is then boiled twice with 200 c.c. of water, or until the last extract is almost, if not entirely, free from colour, when the decoction is diluted to 1 litre. Forty c.c. of this solution is then diluted to 500 c.c. with water, and treated with 25 c.c. of indigo-carmine solution^ and 25 c.c. of dilute sulphuric acid (200 grammes of H2SO4 per litre). The liquid is then titrated with a standard solution of potassium per- manganate (containing approximately 2*6 grammes per litre), and of such strength that 130 c.c. are equivalent to 100 c.c. of deci- normal oxalic acid (6 "3 grammes crystallised acid per litre). The mode of adding the permanganate is important, and Dvorkovitch recommends that in the titration of the indigo-carmine 18 c.c. should be added at the rate of 2 to 3 drops per second, and the remainder at the rate of 1 drop per second ; and that, in the titra- tion of the tea solution mixed with indigo-carmine, 23 c.c. of the permanganate should first be run in, the addition continued at the rate of 2 to 3 drops per second, and finally 1 drop per second added until the reaction is complete. If more than 38 c.c. be required, a small quantity of tea infusion should be used. To estimate the fermentation-products^ 80 c.c. of the tea infusion is mixed with 20 c.c. of baryta- water (containing 4 grammes of baryta ^ Prepared by mixing 50 grammes of pure indigo-carmine paste with water, adding 50 grammes of sulphuric acid and 1 litre of water, filtering, and dilut- ing till 25 c.c require 20 c.c. of the standard permanganate for oxidation. TANNIN IN TEA. 517 per 100 c.c), the liquid filtered, and 50 c.c. of the filtrate (repre- senting 0*4 gramme of the tea) diluted with 500 c.c. of water, mixed with 25 c.c. of dilute sulphuric acid and 25 of the indigo - carmine solution, and titrated with permanganate. 18 c.c. should be run in first of all, then 2 or 3 drops per second added, and finally 1 drop per second till the end of the reaction. Tlie volume of permanganate required, less that reduced by the imligo solution, represents that required for the oxidation of the fermentation- products of 0*4 gramme of tea. According to Dvorkovitch, the joint weight of tannin and fermentation-products is obtained by multiplying the weight of oxalic acid equivalent to the measure of permanganate required for their oxidation by 3 13, since 63 grammes of oxalic acid correspond, according to Dvorkovitch's experiments, to 31 '3 grammes of tea-tannin (as compared to 62 '3 of quercitannic acid !). Employing this process, he found from 8*84 to 10'55 per cent, of tannin, and from 0*90 to r88 of fermentation- products, in teas of the first crop of 1890; and lie concludes that the higher the proportion of cafi'eine to the total amount of tannin and fermentation-products, the more valuable is the tea. The Lowenthal process distinguishes the tannic acid from the small quantity of gallic acid also present in tea, but as the astringent character of the infusion is due to both these substances, a method which will estimate the total amount of astringent matter, without distinction of its nature, is in some respects preferable to a process that gives merely the amount of tannin, while ignoring the gallic acid. Such a process was devised by F. W. Fletcher and the author in 1874 (Chem. News, xxix. 169, 189), and was based on the precipitation of the tea infusion by lead acetate, and the use of an ammoniacal solution of potassium ferricyanide to indicate the complete precipitation of the astringent matters. In practice, 5 grammes of neutral acetate of lead should be dissolved in distilled water, and diluted to 1 litre, and the solution filtered after stand- ing. The indicator is made by dissolving 0'050 gramme of pure potassium ferricyanide in 50 c.c. of water, and adding an equal bulk of strong ammonia solution. This reagent gives a deep red coloration with gallotannic acid, gallic acid, or an infusion of tea. One drop of the solution will detect 0*001 milligramme of tannin, or O'OOl gramme dissolved in 100 c.c. of water. In carrying out the process, three separate quantities of 10 c.c. each of the standard lead solution should be placed in beakers, and each quantity diluted to about 100 c.c. with boiling water. A decoction made from 2 grammes of powdered tea in 250 c.c. of water (the same as is used for determining the extract) is added from a burette, the first trial quantity receiving an addition of 12, the second 15, and the third 518 TANNIN IN TEA. 18 CO.; or if green tea be under examination, 8, 10, and 12 c.c may be preferably employed. Portions (1 c.c.) of these trial quantities are passed through small filters, and tlie filtrates tested with ammoniacal ferricyanide solution. The approximate volume of tea decoction required is thus easily found, and after repeating the test nearly the requisite measure can be at once added. In this case about 1 c.c. of the liquid should be removed with a pipette, passed through a small filter, and drops of the filtrate allowed to fall on to spots of the indicating solution previously placed on a porcelain slab. If no pink coloration is observed, another small addition of the tea decoction is made, a few drops of the liquid filtered and tested as before, and this pro- cess repeated until a pink colour is observed. The greatest delicacy is obtained when the drops of filtered solution are allowed to fall directly on to the spots of the indicator, instead of observing the point of junction of the liquids. The volume of tea solution it is necessary to add to 100 c.c. of pure water, in order that a drop may give a pink reaction with the indicator, should be subtracted from the total amount run from the burette. The foregoing process is simple, and gives very concordant results; but the repeated filtrations requisite for the observation of the end-reaction are apt to be tedious. It is difiicult to obtain pure tannin for setting the lead solution, and hence it is preferable to abandon the attempt and make pure lead acetate the starting- point. The author found that 10 c.c. of the lead solution would precipitate O'OIO gramme of the purest gallotannic acid he could obtain. Hence, if aU the weights and measures above mentioned be adhered to, the number of c.c. of tea decoction required, divided into 125, will give the percentage of tannin and other precipitable matters in the sample. The proportion found in undried black tea by F. W. Fletcher and the author ranged from 8'5 to 11*6 per cent., with an average of 1 per cent. A sample of brown catechu tested by the lead process gave a result corresponding to the presence of 119 per cent, of tannin {sic). (See also page 491.) Another simple method for the determination of tannin is that of J. M. Eder {Dingl. Polyt. Jour., ccxxix. 81), which consists in precipitating the boiling decoction of 2 grammes of tea with excess of a 5 per cent, solution of cupric acetate. The precipitate is separated by filtration, washed, dried, and ignited. The resultant cupric oxide, CuO, can be moistened with nitric acid, re-ignited and weighed as such ; or re-ignited with sulphur in a closed ciucible, and thus converted into an equal weight of non-hygroscopic cuprous sulphide, CugS. The weight obtained, multiplied by 1-305, gives that of the tannin precipitated. The method is said to give CATECHU IN TEA. 519 results correct to within 0*2 to 0"3 per cent. ; but any pectous bodies should be previously separated, if present in quantity, by precipitation with alcohol. By this method Eder found an average 01 about 10 per cent, of tannin in twenty-five samples of black tea, and 12 to 12 J in green and yellow tea. S. J ank e, by the same process, found from 6 "9 to 9"1 per cent, of tannin in black tea (eighteen samples), and 8 "6 to 9*9 in green. Cupric acetate may be extemporised by mixing a solution of cupric sulphate with excess of sodium acetate. C. M. Gaines (page 491) obtained results by Eder's method closely agreeing with those yielded by the same samples with the lead process, and hence the proportion of gallic acid in tea is probably very insignificant. In the case of caper and lie teas, the astringency is often very high, owing to an admixture of extraneous tannin matters ; but the evidence of the presence of such additions afforded by the determina- tion of the tannin of tea is, of course, merely inferential. Strong infusions of genuine tea, with the exception of some kinds from India, are generally quite clear, and do not become muddy on cooling. Tea adulterated with catechu gives an infusion which quickly becomes turbid on cooling. More direct proof of the presence of catechu may be afforded by the following test devised by the author, which, however, should always be applied to the suspected tea side by side with a genuine specimen : — One gramme of the pure tea and an equal weight of the suspected sample are infused in 100 c.c. of boiling water, and the strained liquid pre- cipitated while boiling with a slight excess of neutral lead acetate. Twenty c.c. of the filtrate from pure tea (which should be colour- less) when treated with a few drops of silver nitrate solution (avoid- ing excess), and cautiously heated, gives only a very slight greyish cloud or precipitate of reduced silver ; but the same tea containing 2 per cent, of catechu (purposely added) gives a copious brownish precipitate, the liquid acquiring a distinctly yellowish tinge. With a somewhat larger proportion of catechu, the filtrate from the lead precipitate gives a bright green colour on adding one drop of dilute ferric chloride, while the solution of pure tea gives only a slight reddish colour due to the presence of acetate. On allowing this liquid to stand, the adulterated tea gives a precipitate of a greyish or olive-green colour, the pure tea undergoing no change. These tests, which depend on the properties of catechuic acid, together with the excessive proportion of astringent matters (as shown by the lead process), render the detection of any consider- able proportion of catechu tolerably certain ; but a means, of detecting small additions is still a desideratum. 520 CAPER AND LIE TEA. Catechu is usually introduced in the forms of caper and lie tea, but appears to have been sometimes added in a separate state, to impart additional '* roughness " or to cover the presence of ex- hausted leaves. Caper is a name applied to tea which has been made up into small glossy granular masses by the aid of gum or starch. Some years ago the caper tea from the Canton district was invariably adulterated with sandy and magnetic matter, and often with catechu or other extraneous astringents, together with foreign leaves.^ Notwithstanding the conviction of Wigner and some other authorities that genuine caper tea exists, the author believes it to be invariably a factitious article. Lie tea is the name given to a fraudulent mixture consisting of sweepings and dust of tea and other leaves, mixed with clay, sand, iron ore, &c., and made into irregular masses by means of gum or starch. When put into hot water, lie tea disintegrates and falls to powder. The iodine test for starch may be applied after acidi- fying tlie cold liquid with sulphuric acid, and decolorising with ])ermanganate. The ash of lie tea is sometimes as high as 30 to 40 per cent. The insoluble matter and extract of lie and caper tea are very variable ; but the former, exclusive of mineral matter, is usually considerably below the proportion yielded by genuine tea. The gum 2 in caper tea often amounts to 15 or 20 per cent., while the i?olubIe ash is often less than 2 per cent. The following figures show the results to be expected from the analysis of factitious tea : — A. B. C. Observer, J. Bell. J. M. Eder. A. B. Hill. Description, , " Mahloo mixture." Black tea. Green tea. Extract, 22-40 37-00 Tauniii, Total Ash, . 9-97 19-77 (Catechu detected) 3-07 Catechu detected. 12-10 Magnetic and sandy matter, 4-31 6-00 Soluble Ash, . 1-54 1-12 1-29 Alkalinity, as K2O, . 0-17 ... 0-13 ^ At the present time (August 1892), Canton capers are frequently loaded with from 3 to 5 per cent, of sand, &c., but they rarely appear in the home market, being stopped by the Customs, or purposely imported for future ex- portation (M. J. Sheridan). '^ The gum is determined by concentrating the aqueous decoction of the tea FACTITIOUS TEA. 521 The following analyses of samples of spurious tea, received from the U.S. Consuls at Canton and Nagasaki, are by J. P. Batter- shall {Food Adulteration^ page 28). No. 1 consisted of partially exhausted and refired leaves known as " cliing suey " (clear water), a name apparently referring to the character of the infusion. No. 2 was a sample of "lie-tea" made from wampan leaves. No. 3 was a mixture of 10 per cent, of green tea with 90 per cent, of lie-tea, sometimes sold as "Imperial" or "Gunpowder" tea. No. 4 was a sample of "scented caper," consisting of tea-dust made up into little shot-like pellets by means of " Congou paste " (boiled rice) : — No. 1. No. 2. No. 3. No. 4. Insoluble leaf, Extract (complete), Gum, . Tannin, . Caffeine, Ash :— Total, Soluble in water. Insoluble in acid, 70-60 7-73 10-67 8-13 0-58 8-62 0-64 3-92 70-65 14-00 7-30 801 none 8-90 1-86 3-18 67-00 12-76 11-00 14-50 0-16 7-95 3-00 1-88 60-10 22-10 11-40 15-64 0-12 12-58 3-84 6-60 Logwood is mentioned by Eder as an adulterant of tea. To detect it, he steeps the tea in cold water. If logwood be present, the resultant solution is changed to a bright green on adding a little sulphuric acid, and to blackish-blue by a solution of neutral chromate of potassium. Facings and colouring materials were formerly almost invariably present in green tea,^ the object being to impart a hue demanded by custom but not naturally possessed by the leaf. Colouring matters have been extensively employed for transforming black tea of low quality into superior green. In the case of Roberts v. Egerton, heard before the Court of almost to ail extract, treating the residue with strong spirit, and filtering and washing with spirit. The precipitate is rinsed off the filter with hot water, and the solution evaporated to dryness at 100°. The residue is weighed, ignited, and the ash weighed. The loss is regarded as "gum," but is liable to be in excess of the truth from the presence of albuminous matters. ^ It is a fact well known to the trade that for many years a certain firm of tea merchants used some method of removing the facing after the arrival of the tea in this country. 522^ FACINGS OF TEA. Queen's Bench in 187 4, Mr Justi(;e Blackburn decided that the facing of green tea with gypsum and prussian blue was an adulteration, because natural green tea could be obtained without such means.-'- If a faced tea , be examined under the microscope as an opaque object, the nature of the facing materials may often be recognised. On treating a faced tea with warm water, the colouring matters become detached', and the small portions rising to the surface may be floated on to a glass slide and at once examined under a micro- scope, while the bulk of the facing is obtained as a sediment when the strained liquid is allowed , to stand. ^ Foreign leaves in tea are legitimately present in small proportion (1 to 3 per cent.) to impart bouquet,^ but larger admixtures can simply be regarded as due to adulteration. Sloe, elder, and willow leaves have been (formerly) met with in England as adulterants of tea.* Among the recently-found leaves added abroad, and stopped by the Customs, are those . gf ChlorantJms inconspicuus, Camellia sasanqua, Eurya Chinensis, and sloe.^ In the recognition of foreign ^ The teas consumed by the Chinese and Japanese themselves are not faced. According to Y. Kozai the maximum proportion of facing in the green tea of Japan is about 0*4 per cent. ^ This deposit often has a distinctly greenish colour from the presence of prussian blue or indigo. Indigo may be recognised by its behaviour with nitric acid. Prussian blue is best detected by warming the sediment with caustic alkali, filtering, strongly acidulating the filtrate with hydrochloric acid, filter- ing again if necessary, and testing the clear liquid for ferrocyanide with ferric chloride. On treating tlie sediment with the alkali it is sure to turn brown, but this change must not be regarded as aTi indication of the presence of prus- sian blue. The residue left after treatment with the caustic alkali should be treated with hydrochloric acid, when the insoluble portion will usually consist of steatite or other Tnagnesian silicate, the use of which gives the tea a peculiar smooth appearance and slippery feel. Calcium sulphate is often employed for facing tea. Caper tea is often glazed with graphite. Turmeric has been detected by some observers, but in the experience of the author the yellow colouring matter has generally been of a ferruginous nature. ^ As a rule, the odoriferous leaves are not allowed to remain in the tea, but having imparted their characteristic fragrance to the tea are removed previously to packing. * From the result of a parliamentary inquiry held in 1835, it appeared that upwards of four million pounds of factitious tea were annually prepared in this country from sloe leaves, and used to adulterate China tea. Up till within a few years of that date this illicit practice was carried on secretly, but subse- quently a patent was obtained for the preparation of British leaves as a substi- tute for tea, and an extensive manufactory was established for this purpose. The industry was ultimately suppressed, and a large quantity of the product burned. * In 1888 Wen da and Wiorogorski found in the teas sold in Warsaw various foreign leaves, which they identified by their anatomical characters. FOREIGN LEAVES IN TEA. 523 leaves in tea, chemistry cannot be expected to play a very active part, though it sometimes affords very useful indications. Thus A. Wynter Blyth has pointed out {Analijst, ii. 39) that a crystalline sublimate (which he believes to be theine) is obtainable from a single leaf of tea. For this purpose he boils the leaf for a minute in a watch-glass with a very little water, adds an equal bulk of calcined magnesia, and evaporates the mixture rapidly to a large drop, which is transferred to a microscopic covering glass and evaporated nearly to dryness on a heated iron plate. It is then covered by a ring of glass, and when the moisture is nearly diiven olf a second slip of glass is added as a cover. At a somewhat higher tempera- ture theine volatilises, and on examining the deposit on the covering under the microscope may be recognised by its character- istic appearance. Other leaves than tea may give a crystalline sublimate, but if no sublimate is obtained the leaf cannot be a product of the tea-plant. A. W. Blyth has also proposed to utilise the constant presence of manganese in tea-leaves as a means of recognising them. If a single tea-leaf be ignited in platinum, and the ash taken up in a bead of sodium carbonate contained in a loop of platinum wire, on remelting the flux after a minute addition of nitre the green colour of the sodium manganate will be distinctly recognisable. Or a minute quantity of nitre and carbonate of sodium can be at once added to the ash on the platinum foil, when on fusing the mixture a distinct green colour will be obtained if manganese be present. The author has found manganese in the leaves of Camellia Thea (tea), Camellia Japonica, Camellia sasaTiqua, Coffea Aralica, beech, blackberry, and sycamore. Manganese was absent from the leaves of the hawthorn, ash, raspberry, cherry, plum, and rose ; and only faint traces were detected in the leaves of the Rex Paraguayensis, elm, birch, lime, sloe, elder, willow-herb, and willow. For the detection and identification of foreign leaves in tea, the botanical and microscopical characters are best fitted. Some of the sample to be examined should be put into hot water, and Among the leaves recognised were those of Epilobittm angiistifolium, or French willow-herb, which formed the great part of the "tea" sold in certain localities. They also found the leaves of Epilohium hirsutum (great willow- herb), Ubnus campestris (elm), Prunus spinosa (sloe), Fragaria vesca (straw- berry), Fraxinus excelsior (ash), Sambucus nigra (elder), Rosa canina (dog- rose), and Ribes nigrum (black currant). The infusion of willow-herb is darker than that of tea, and gives a precipitate of mucilage on treatment with alcohol. An article known in Russia as "Karpar tea" also contains an admixture of the leaves of Epilobium angustifolium. Two samples examined by J, Nikitinsky in 1885 yielded 7*87 and 10*43 per cent, of ash, six repre- sentative genuine teas yielding from 5 '60 to 6 '87 per cent. 524 CHARACTERS OF TEA LEAVES. when the leaves have unfolded they are spread out on a glass plate and held up to the light, when, with the aid of a lens, the venation, serration, &c., can be readily observed. A valuable aid to the examination consists in treating the leaves with a solution of sodium hypobromite, or, as suggested by A. Wynter BlyLh, a strongly alkaline solution of potassium permanganate. In using the reagent, the leaf should be enclosed between two microscopic cover-glasses, a weight being placed on the upper one to keep it in position. On heating the leaf with the reagent, action at once commences, the colouring matter being first attacked and sub- sequently the cell-membranes. When the action is sufficiently advanced, the leaf is removed, washed, and immersed in hydro- chloric acid, which leaves the leaf as a translucent white membrane in which the details of structure can be readily observed. J. Bell removes the skin of the leaf by immersing it in " water containing a few drops of nitric acid," and gradually heating to the boiling- point, when the skin rises in blisters, and may be readily removed by a camel's-hair brush. The primary venation of the tea-leaf consists of a series of well- defined loops, which are not met with in most leaves likely to Ije used as adulterants. The serrations are not mere saw-teeth on the margin of the leaf, but actual hooks.^ The serration stops short abruptly at some distance from the base. The Assam tea-loaf is sometimes biserrate. At the apex of the tea-leaf there is a distinct notch, instead of a point. The epidermis of the under-surface is seen under the microscope to consist of distinct sinuous cells, with numerous oval stomata, and a few, long unicellular hairs.^ On the upper surface the stomata are less numerous. If tlie under surface of the tea-leaf be examined under the microscope after separation of the cuticle, the peculiar and characteristic space between the twin cells of the stomata may be readily perceived. T. Taylor has pointed out the presence of "stone cells "in the leaves of tea and Camellia Japonica^ and confirms the observa- tions of Blyth as to the absence of these formations in the leaves of the willow, sloe, beech, ash, black-currant, raspberry, and Ilex Paraguay ensis. Taylor prepares the leaves for examination by boiling them in a strong solution of caustic potash or soda. ^ The serrations are verj- strongly marked on mature leaves, but are indis- tinct or almost wanting in the delicate leaf-buds which constitute "flowery pekoe." ^ Tea-hairs are conical, pointed, slightly bent towards the base. They have very thick walls, and the central duct usually contains granular matter. Numerous hairs are observable ou young tea-leaves, but on old leaves they are boiuetimes wholly wanting. FOREIGN LEAVES IN TEA. 525 In the leaf of the blackthorn or sloe {Prunus communis or P. spinosay the serratures are direct incisions, numerous, often irregular, and extending to the base. There are no spines. The cells of the epidermis are not sinuous, and are much smaller than those of tea, especially on the under surface. The cells on the upper surface are striated. The stomata of the sloe-leaf are smaller and less numerous than those of tea. The hairs are shorter and coarser than those of the tea-leaf ; are marked in a peculiar manner, and have a club-shaped enlargement at the base. The leaf of the elder (Sambucus nigra) is more pointed than that of the tea-plant, and the lobes are unequal at the base. The serrations are direct incisions. The midriff has hairs on it, and on the leaf itself there are two distinct kinds of hairs — one, a short, spinous hair, and the other jointed and club-like. In the leaf of the willow (Salix alba) the serrations much resemble those of tea, but the cells of both the upper and under epidermis are much smaller than in tea, and the walls are not sinuous. The hairs, which are very abundant on both sides of the leaf, are long, unicellular, and sinuous. The elongated form of the willow-leaf and the character of the venation also distinguish it from tea. The appearance of the leaf of the hawthorn (Cratcegus monogyna and C. oxyacantha) is well known. The cells of the epidermis are mostly quadrilateral, with very sinuous outlines, especially on the under surface. The stomata are oval or nearly round, large, and numerous. The leaves of the beech {Fagus sylvatica) are ovate, obscurely dentate, with parallel venations running right to the edge. The leaves of Qhloranfhus inconspicum are long, oval, serrated, wrinkled, with venations running nearly to the edge, and there by their intersection forming little knots which give the margin of the leaf a very rough feeling. The cells of the epidermis are very large, and the stomata oval and rather numerous. The leaves of Camellia sasanqua are oval, only obscurely serrate if at all, and of a tough leathery texture. The lateral veins are inconspicuous. Both the upper and lower epidermis show a peculiar dotted or reticulated structure, and the lower is studded with numerous small oblong stomata. The leaves of Lithosj)ermum officinale (the common gromwell) have been extensively used in Bohemia for adulterating tea. They ^ A specimen of sloe-leaves gathered early in September gave, after drying, the following results (in the author's laboratory): — Moisture, 6*40 j)Hrcent. ; insoluble matter (on whole leaves), 55*90 ; tannin (by gelatin), 16'00 ; gum, &c., 8*90 ; total ash, 8*74 ; and ash soluble in water, 4*70 per cent. 526 . ILEX. PARAGUAYENSIS. are lanceolate, with a hairy under-surface, are destitute of alka- loid and essential oil, contain about 9 per cent, of fat and 8 of tannin, and leave about 20 per cent, of ash on ignition {Jour. Chem. Soc, xl. 131). The general appearance and venation of tea, and leaves which have been, or may possibly be, employed for its adulteration, are shown by two plates at the end of the volume (page 572). The illustrations are life-size reproductions, by the collotype process, of photographs of leaves, taken by J. T. S t e v e n s o n in the author's laboratory. A. Wy nter Blyth has pointed out the characteristic appear- ance of the "skeleton-ash" left on igniting leaves from different sources. The leaf to be examined is placed between two circles of microscopic cover-glass, the upper one weighted with a silver coin, and the whole ignited cautiously in a flat platinum dish, or on platinum foil. Before the carbon is completely consumed the heat is discontinued, and the skeleton-ash examined under the microscope. Mate. Paraguay Tea. Mate^ orYerba consists of the prepared twigs and leaves of Ilex Paraguayensis, or Brazilian holly.^ Byasson found in caa-guacu, the commonest kind of mate, consisting of the large and old leaves with twigs and fragments of wood: — Caffeine, 1*85 per cent.; a substance resembling bird- lime, fatty and colouring matters, 3 "87 ; complex glucoside, 2*38 ; resin, 0*63 ; mineral matter, 3*92 ; and an undetermined propoi>- tion of malic acid. Some fresh leaves of Bex Paraguayensis, grown in Cambridge Botanical Gardens, were found in the author's laboratory to contain 69*1 per cent, of water. An analysis of the same leaves after drying at 100° C. showed: — Insoluble matter, 57*94 ( = hot-water extract, 42-06); tannin by PbAg, 15*62; tannin by CuAg, 15"66; caffeine, 1"13; total ash, 6*14; soluble ash, 3'56 ; alka- linity of soluble ash (as KgO), 0"12 per cent. A. W. Hofmann found in mate 0'3 per cent, of caffeine and a variety of tannin identical in every respect with that present in tea. ^ The word mate is not accented, as sometimes written, but it should be pronounced as two syllables. 2 Various allied species are recognised, but Ilex Paraguayensis appears to be the only one cultivated. It has been grown in Spain, Portugal, and Cape Colony, in addition to its native habitat. At the present time it is used by about 12,000,000 of peo})le, the annual consumption in the Argentine Republic alone being twenty-seven million pounds. TEA SUBSTITUTES. 527 P. JSr. Arata found the tannin of mate to be analogous to but not identical with that of coffee. On dry distillation he found it to yield resorcinol as well as catechol. Caffetannic acid he regards as dioxy- paracinnamylic acid, and matetannic acid as belonging to the group of oxyphenylpropionic acid. Soubeiran and Delondre state that mate contains the same essential constituents as the coffee-leaf, and in greater proportion than the coffee-seeds. This conclusion is confirmed by Theodore Peckolt in a valuable resume of the subject {Pharm. Jour., [3], xiv. 121), including some elaborate proximate analyses of mate. The aromatic principle of mate has not been isolated, but by dry distillation a volatile oil of phenolic character is obtained. The ash of mate resembles that of tea in containing a notable proportion of manganese. The leaves of the Y o p o n {Ilex cassine)^ a shrub or small tree growing on the coast of Virginia and Carolina, have been used as a beverage.^ F. P. Yen able (Chem. News, lii. 172) found in an air-dried sample: — Moisture, 13'19; water extract, 26*55; tannin, 7*39 ; caffeine, 27; and ash, 6 '7 5 per cent. The ash contained manganese. Coffee.^ Commercial coffee consists of the seeds of Coffea Arabica and allied species belonging to the order Ginclionacece.^ The coffee- tree is a shrub-like plant cultivated in various tropical countries. The best coffee that reaches England comes from India, Java, and Ceylon. A little "Mocha" coffee comes from Arabia, but the 1 Although the leaves of tea, coffee, and Brazilian holly are almost the only ones known to contain caffeine, a beverage is prepared from the leaves of many other plants in various parts of the world. Thus, Catha edulis, a shrub related to the spindle tree, is extensively cnltivated in the interior of Arabia, and the leaves, known as K h a t, C a ft a or Arabian tea, are used both as a beverage and for chewing. Fahuin, or orchid tea, is made from the leaves of Angrcecumfragram, growing in the Mauritius, and some years since was intro- duced into Paris as a regular article of commerce. Th^ Arab e, a substitute for tea which has been sold in Paris, consists of the small leaves of Paronychia argentea, a plant growing on the slopes of the Atlas Mountains. Batoum or Trebizonde tea is made from the leaves of Vaccinium ardostaphylos, a plant closely allied to the cranberry. Cape tea and Bush tea are described in the footnote on page 503. Karper tea is described on page 523. 2 French ; le CafL German ; der Kaffee. 3 Three species oi Coffea, distinct from each other, are now grown : 1. The Arabian or Mocha coffee-plant has short upright branches, with a brittle leaf and seeds usually single in the berries. 2. The Jamaica coffee-plant bears longer and more pliable branches than the Arabian, has a tougher leaf, and the seeds are almost always double in the berries. 3. The East Indian or 528 COMPOSITION OF RAW COFFEE. greater part from India. Brazil at the present time furnishes about one-half of the world's supply of coffee.^ Commaille {Monit Scient, [3], vi. 779) gives the following as the chemical composition of undressed Mysore coffee : — Moisture (from 24 samples), 6*3 to 15-7 per cent.; fatty matters, 12-68; glucose, 260; legumin-casein, 1*52; albumin, 1'04; caffeine, 0'42 to 1*31 ; and ash, 3*88 per cent. 0. Levesie (Arch. Pharm., [5], iv. 294; Jour. Chem. Soc.y xxxi. 752) obtained the following range of figures by the analysis of seven typical samples of raw coffee ; — Caffeine, Gummy matter, Fat, . Tannic and caffetannic acids, Cellulose, Ash, . 0*64 to 1-53 per cent. 20-6 „ 27-4 14-76 „ 21-79 19-5 ,, 23 1 29-9 „ 36-4 3-8 „ 4-9 It J. Bell (Analysis and Adulteration of Foods, i. 43) gives the following analyses of typical samples of raw and roasted coffee : — Bengal plant has smaller leaves than the Jamaica coffee, and very small berries. The Liberian coffee-plant {Coffea Liberiea) appears to be a distinct species, which is little subject to disease, and has been successfull)' introduced into the East Indies. The coffee fruit usually, but not always (see above), contains two twin seeds, which touch each other on the flattened surface. These are contained in a pulp which is removed by water and a process of fermentation ; and the membranous pericarp (technically termed "parchment") which incloses each seed is removed by rollers and winnowing. The parchment from coffee-berries is imported to England in considerable quantities, and, when roasted, is said to form an ingredient of the beverage sold in cheap coffee-shops. An analysis of unroasted "parchment," made in the author's laboratory by C. M. Gaines, showed it to contain : — Water, 9*43 ; essential oil, 068 ; caffeine, 0*27 ; hot-water extract, I'Gl ; total ash, 10-41 ; and soluble ash, 0*19 per cent. A somewhat coffee-like aroma was developed by roasting. It is stated that the Arabs in the neighbourhood of Jedda discard the kernel of the coffee-berries and make an infusion of the husks {Pharm. Jour., [3], xvii. 656). ^ In Australia, an infusion of slightly roasted coffee-leaves is drunk in the same manner as tea. Its taste suggests at once that of tea and tobacco. The leaves, when burnt or roasted, exhale a powerful odour of tobacco, and the smell of the condensed vapours strongly suggests that of tobacco -juice. 0. Hehner, who has analysed the leaves {Analyst, iv. 84), found only 0*29 per cent, of caffeine. COMPOSITION OF COFFEE. 62i) Mocha Coffee. East Indian Coflfee. Raw. Roasted. Raw. ... Roasted. Moisture Caffeine, Saccharine matter, Caffeic acids Alcoholic extract, containing ) nitrogenous and colouring [• matter, . . . . ; Fat and oil, Legumin and albumin, . Dextrin, Cellulose and insoluble colouring") matter, . . . . / Ash, 8-98 1-08 9-55 8-46 6-90 12-60 9-87 •87 37-95 3-74 0-63 •82 •43 4-74 14-14 13-59 11^23 1-24 48-62 4-56 9-64 1-11 8-90 9-58 4-31 11-81 11-23 -84 38-60 3-98 1-13 105 •41 4-52 12-67 13-41 13 13 1-38 47-42 4-88 100-00 100 00 100-00 100-00 Bell believes the sugar of coffee to be a peculiar species, possibly- allied to melezitose. G. L. Spencer, on the other hand, has definitely proved that the carbohydrates of coffee consist very largely of sucrose, which he has isolated in considerable quan- tities. There is likewise present a body which yields galactose on hydrolysis, as also a pentose-yielding gum. Caffetannic Acid, CigHigOg, called by Payen chlorogenic acid, exists in coffee-berries in the proportion of 3 to 5 per cent., probably as a calcium or magnesium salt, or, according to Payen, as a double caffetannate of potassium and caffeine. It is prepared by diluting an alcoholic infusion of coffee with water, filtering from precipitated fatty matter, and precipitating the boiling filtrate with lead acetate.^ On decomposing the washed precipitate with sulphuretted hydrogen free caffetannic acid is obtained. It forms a yellowish-white powder, or groups of colourless mammillated ^ W. H. K r u g determines caffetannic acid as a lead salt He treats 2 grammes of coffee with 10 c.c. of water, and digests for 36 hours, then adds 25 c.c. of rectified spirit, and digests 24 hours more. The liquid is filtered, the residue washed with rectified spirit, and the filtrate heated to the boiling- point. A boiling concentrated solution of lead acetate is added, which throws down a precipitate of Pb3(Ci5Hi508)2. When this has become flocculent it is filtered off, washed with alcohol till the washings are free from lead, washed with ether to remove traces of fat, dried at 100°, and weighed. VOL. III. PART II. 2 L 530 CAFFETANNIC ACID. crystals. It is very soluble in water, less soluble in alcohol, and only very sparingly in ether. Caffetannic acid has an astringent taste, and the solution strongly reddens litmus. It gives a dark green coloration with ferric chloride, and precipitates the sulphates of quinine and cinchonine ; but not gelatin, ferrous salts or tartar- emetic. It reduces silver nitrate on heating, forming a metallic mirror. The salts turn green in the air. On dissolving caffetannic acid in caustic alkali or ammonia, and exposing the solution to the air, the liquid acquires a bluish-green colour owing to the formation of the oxidation-product, v i r i d i c acid, which is an amorphous brown substance, very soluble in water to form a solution which is turned green by alkalies. It gives a bluish-green precipitate with baryta-water, and a blue with lead acetate. Viridic acid dissolves in concentrated sulphuric acid to form a crimson solution, which on dilution with water gives a flocculent blue precipitate. On prolonged boiling with caustic alkalies, caffetannic acid is split up into a sugar and caffeic acid, CgHgO^, which crystallises from the neutralised liquid and has the constitution of a dihydroxy-cinnamic acid. By fusion with caustic potash, caffetannic acid yields protocatechuic and acetic acids. Heated alone it gives catechol. Roasting of Coffee. During the process of roasting, the aroma of coffee is developed and the toughness of the beans destroyed, so that subsequent grinding is facilitated. If the roast- ing be insufficient, the rawness is not destroyed and the flavour not fully developed; while if over-roasted, the product has a nauseous empyreumatic flavour. When roasted to a yellowish -brown, coffee loses, according to Cadet, about 12 J per cent, of its weight, and in this state is difficult to grind. When roasted to a chestnut-brown it loses 18 per cent., and when it becomes entirely black, though not all carbonised, it has lost 23 per cent. In practice, the loss of weight in roasting coffee is between 12 and 20 per cent, (of which about 8 per cent, represents water removable at 100° C), and if the latter figure is reached, the product is injured. According to Watson Will, the usual yield of roasted coffee is about 98 lbs. from 1 cwt. of raw berries. This corresponds to a loss of 12*5 per cent. K o n i g found that on roasting coffee-berries to a light browR the total loss of weight was 1777 per cent., of which 8*66 was water and 9'11 per cent, organic matter. The original coffee con- tained 11*19 per cent, of moisture, and after roasting, still retained 3*19 per cent. Eliminating this extraneous water from the results. ROASTING OF COFFEE. 531 the percentage composition of the raw and roasted coffee was as follows : — Raw. Roasted. Caffeine, 1-33 per cent. 1-42 per cent. Fat, 14-91 „ 16-14 Albuminous matters, .... 11-43 „ 12-31 Sugar, 3-66 „ 1-35 „ Undefined non-nitrogenous matters, 34-55 „ 39-84 „ Cellulose, 31-24 „ 25-07 „ Ash 3-92 „ 3-87 „ 101-04 (!) per cent. 100-00 per cent. Total matters soluble in water, . 30-93 per cent 28'36 per cent. According to Paul and C o w n 1 e y {Pliarm. Jour., [3], xvii. 655, 821) there is no appreciable loss by volatilisation of caffeine during the roasting of coffee, unless the process is carried to excess. But Paul admits that the water condensed in the place leading from the roasting often contains some caffeine, which he considers has been probably carried over mechanically (Pharm. Jour., [3], xvii. 821). Watson Will (ibid., page 684) states that he has never failed to find caffeine in the sublimate obtained in coffee- roasting. The chemistry of the roasting of coffee has been studied by 0. Bernheimer {Monatsh. Chem., i. 456 ; Jou7\ Chem. Soc, xlii. 230), who roasted coflee till it had lost about 25 per cent, of its weight.^ The uncondensible vapours consisted chiefly of carbon 1 Paul points out that the caffeine exists in coffee in the form of cafFetannate, which compound will not suffer decomposition at the ordinary temperature of roasting. Considering the great facility with which salts of caffeine undergo decomposition, this statement seems to require confirmation. 2 Fifty- kilogrammes of coffee yielded 5 litres of aqueous distillate and 680 grammes of solid matter floating thereon. On agitating this with ether, fatty acids, quinol and caffeol were extracted, while caffeine, acetic acid, methyl- amine and trimethylamine remained in the aqueous liquid. On evaporating the ethereal solution, and fractionally distilling the residual dark, coffee-smelling oil, a few drops of an acetone-like liquid passed over, followed by a little acetic acid and water. Between 200° and 300° caffeol distilled, and above that tem- perature palmitic and other solid fatty acids. On neutralising these and the 200°-300° fraction with sodium carbonate, a viscid dark oil was thrown dowu, 532 CAFFEOL. dioxide, and by passing them through dilute hydrochloric acid a resinous substance having the appearance of pyrrol-red was deposited. Among the solid and liquid bodies volatilised, Bern- heimer found : — Palmitic and other solid fatty acids, 0*48 per cent.; caffeine, 0*28 per cent.; caffeol, 0*05 per cent.; besides water and acetic acid. Quinol, pyrrol, acetone, methylamine, and trimethylamine also occurred as secondary products. Caffeol, CgH^QOg, is an oily liquid smelling very strongly of coffee, and no doubt is the substance to which the aroma of roasted coffee is due. It may be obtained by distilling roasted and powdered coffee with water, shaking the distillate with ether, and evaporating. Caffeol boils at 196°, and is not solidified by a freezing mixture. It is not sensibly soluble in cold water, to which, however, it im- parts its characteristic odour. It is slightly soluble in hot water, very slightly in aqueous potash, and with great facility in alcohol and ether. The alcoholic solution gives with ferric chloride a red coloration, said not to be destroyed on adding sodium carbonate. By fusion with caustic potash, caffeol yields saHcylic acid, and, according to Botsch (Monatsh. Chem., ii. 621; Jour. Chem. Soc, xlii. 174), is isomeric with methyl-salicyl alcohol, tlie two compounds having the following constitution : — CeH4(O.CH3).CH20H C6H,(OH).CH2.0CH3 Methyl-salicyl alcohol. Caffeol. Paul and Cownley {Pharm. Jour., [3], xvii. 822) found that on infusing coffee in six times its weight of boiling water, about 88 per cent, of the caffeine passed into solution. Three fluid ounces of such an infusion contained 2*36 grains of caffeine. As the medicinal dose of caffeine is from 1 to 5 grains, a cup of coffee may be expected to have a marked effect as a stimulant. The dietetic value of coffee is possibly dependent as much upon the presence of caffeol as on that of caffeine. According to M. P a r g a s, the effect of caffeol on the heart's action is the opposite to that of caffeine, and increases the strength and rapidity of the pulsations. According to C o u t y, G u i m a r a e s, and N i o b e y (Compt. Bend., xcix. 85) coffee diminishes the activity of the simple com- bustions which produce carbon dioxide, but increases the forma- which was separated from the aqueous solution of soap and washed with water containing a little caustic alkali. This dissolved out quinol, which was isolated by acidulating the washings and extracting with ether. The viscid oil, con- sisting of impure catfeol, was dried by calcium chloride and fractionally dis- tilled, when the greater part passed over between 195° and 197°. PHYSIOLOGICAL EFFECTS OF COFFEE. 533 tion and excretion of urea, and the assimilation of meat and other nitrogenous foods. It is a complex aliment which renders the organism capable of consuming and destroying larger quantities of nitrogenous substances, and hence may be regarded as an indirect source of available energy. Commercial coffee is subject to a variety of sophistications, both in the form of berry and after grinding. So far as the United Kingdom is concerned, the majority of the frauds formerly practised are obsolete, or nearly so, but certain illicit practices subsist. Coffee-berries vary considerably in size and character accord- ing to their origin.^ The following table shows the number of seeds required to fill a 50 c.c. measure (Thorpe's Diet. Applied Chem., ii. 578) :— Fine brown Java, 187 Good ordinary Java, . 223 Fine Mysore, . 198 Fine Ceylon plantation, . 225 Fine Neilgherry, 203 Good average Rio, 236 Costa Rica, 203 Medium Ceylon planta- Good ordinary Guatemala, 207 tion 238 Good La Guayro, 210 Manilla, .... 248 Good average Santas, 213 Ordinary Mocha, 270 Fine long-berry Moo-ha, 217 West African, . 313 According to L. Pad^ (Bull. Soc. Ghim., xlvii. 501), raw coffee which has been damaged by sea-water is sometimes washed, de- colorised with lime-water, again washed, dried rapidly, and coloured either by slight roasting or by dyeing with azo-oranges. By such manipulations, green Santas coffees are said to be increased 25 per cent, in value, and made to pass for Java growths. E. "Waller states that South American coffees are often exposed to a high moist heat, which changes their colour from green to brown, in imitation of Java coffee. He found coffee-berries coloured with Scheele's green, yellow ochre, chrome-yellow, burnt umber, ^West Indian coffee-berries are regular in size, pale yellowish, firm and heavy, with a fine aroma, and they lose comparatively little on roasting. Brazilian coffee is larger, less solid, greenish or white, and usually classed as ' ' low "or " low middling. " Javanese coffee-berries are smaller, slightly elongated, light, and deficient in aroma and essential oil. When new, Java coffee is pale yellow, and of less value than when old and brown. The deeper colour is due to curing as well as age. It has been artificially coloured. Ceylon produces all descriptions of coffee, but the ordinary plantation coffees are even-coloured, slightly canoe-shaped, strong in aroma and flavour, heavy, and more susceptible of adulteration than the other kinds. Genuine Mocha coffee is small and dark yellow in colour, and considered of the highest quality. 534 COFFEE-BERRIES. Venetian red, &c. When possible, such facings should be detached by agitating the berries with cold water and examining the sediment. Organic colouring matters can be detected by- soaking the berries in alcohol, which is not coloured by genuine coffee. On evaporating the alcoholic solution to dryness, and taking up the residue in water, a solution will be obtained which will give the characteristic reactions of the coal-tar dyes. The specific gravity of twenty-four samples of genuine raw coffee-berries was found by Pad^ to range from 1"368 to 1041, while the density of the same samples, after roasting in the ordinary manner, varied from 0*635 to 0"500. Raw coffee which is lighter than water may be suspected of having been damaged by sea- water or other means, and subsequently washed and improved in colour by partial roasting. The specific gravity of coffee-berries is ascertained by Pad^ by a special apparatus described in his paper. In the case of unroasted coffee, the gravity can be readily observed by immersing a few of the berries in saturated brine, which is then diluted with water till the coffee remains suspended in the liquid, the specific gravity of which is then taken. With roasted coffee, the brine must be replaced by the very lightest gasolene, the density of which can be increased if necessary by the gradual addition of ordinary kerosene. Another plan of ascertaining the specific gravity of coffee-berries is to introduce as many as possible into a tared 50 c.c. flask or other vessel of known capacity. The weight is then ascertained, and the flask filled to the mark with mercury. The weight is again observed, when the increase will be the weight of mercury required to fill the interstices between the berries : — Weight of berries in grammes x 13;59 ^^ ^^^.^^^^^ (Measure of vessel in c. c. x 13-59) - weight of interstitial mercury According to J. K b n i g (Zeitsch. angew. Chem., 1888, page 680) coffee is often roasted with an addition of glucose-syrup, which makes the decoction look stronger, and causes the berries to hold an additional 7 per cent, of water.^ L. P a d ^ states that roasted 1 Coffee so treated yields from 6 to 8 per cent, of soluble matter on agitation with cold water, while coffee roasted without sugar yields from 4 to 5 per cent, only. In the former case, Fehling's solution indicates from 1 to 1^ per cent, of reducing sugar, against 0"2 to 0'5 in genuine coffee. Stutzer and Reitnair detect glucose by violently agitating 20 grammes of the coffee- beans with 500 c.c. of water for five minutes. The liquid is further diluted to 1000 c.c. and 50 c.c. of the filtered liquid evaporated to dryness at 100°. The dry residue is weighed, ignited, and the ash deducted. Pure roasted IMITATION COFFEE-BERRIES. 535 coffee-beans can be made to take up nearly 20 per cent, of water by steaming them and coating them with glycerin, palm-oil, or vaseline to prevent evaporation. The specific gravity of the berries is thereby raised to 0*650-0'770, and hence is sensibly above 0*635, which is the maximum figure for genuine roasted berries. YanHamel Roos {Revue Intern, des Falsifications, May 1 5, 1891) has called attention to an ingenious method of sophisticating coffee-berries. A sample examined by him had the microscopic structure of genuine coffee, but showed an almost entire absence of fat globules, and gave an ether-extract of less than 1 per cent, (instead of 12 to 14). Roos suggests that the berries had been used for preparing coffee-extract, and then re-roasted with addition of a little sugar. As a coating for coffee, T. W. Moore has patented {Eng. Pat., 5033, 1889) a mixture of milk or condensed milk, ground or powdered glue, " liquid glycerin," and refined lard; with the addition in some cases of bicarbonate of soda, fine salt, and vinegar ! Imitation coffee-berries were formerly manufactured of fire-clay. These were mixed with genuine berries and roasted with them, when they absorbed some of the colouring matter and oil, and so remained a close imitation. On breaking such spurious berries the colour would be seen to be principally on the exterior. The determination of the total ash and silica would at once lead to the detection of such a fraud. In 1850, Messrs Duckworth of Liverpool took out a patent for moulding chicory into the form of coffee-berries, and quite recently several kinds of factitious coffee-beans have been described. A factory for the manufacture of imitation coffee-berries on the scale of 40 to 50 kilogrammes daily was recently seized at Lille by the French Government. It appeared in evidence that the com- position of the product was : — Chicory, 15 kilogrammes; flour, 35 kilogrammes ; ferrous sulphate, J kilogramme. Factitious coffee-beans recently seized in Roumania consisted of coffee-grounds, chicory, and peas. In America there are several firms which extensively manufacture imitation coffee-beans and " coffee-pellets." These preparations usually consist of wheat-flour, chicory, bran, and occasionally coffee. Samples purchased and examined by the chemists of the U.S. Department of Agriculture gave the following re- sults : — coffee shows from 0*44 to 0"72 per cent, of soluble organic matter, and gives a solution only faintly coloured ; but if roasted with sugar or glucose the organic extract ranges from 1*81 to 8*18 per cent., and the liquid is more or less strongly coloured. 536 FACTITIOUS COFFEE-BEANS. Appearance. Specific Gravity. Composition. Roasted beans, . . Roasted beans, . . Roasted beans, . . Roasted pellets, . . Roasted pellets, . . Roasted pellets, . . Raw beans, .... Roasted beans, . . Light-coloured beans, Dark- coloured beans. Roasted beans, . . Roasted granules. Roasted lumps, . . Roasted granules, . 1-195 1-198 1-111 1-119 1-183 1-193 1-211 1-174 1-134 1-118 Wheat-flour. Wheat-flour, coffee, and chicory. ' ' Kunst Kaflee. " Wheat-flour, coffee, and chicory. VWheat-flour, bran, and probably rye. Wheat-flour and coffee. Wheat-flour. 1 Wheat-flour and probably sawdust. Wheat-flour. Hulls of peas, with molasses. Bran and molasses. Pea hulls and bran. A. W. Kehnstrom {Eng, Pat, 14,970, 1889) has described a substitute for coffee prepared by boiling down whey or milk in a vacuum to a pasty consistency, forming the product into cakes, drying it below 100°, cutting it into pieces the size of coffee-beans, and roasting. L. Jaunnes, in 1891, examined a factitious coffee consisting of acorns and cereals. An imitation coffee examined by J. K d n i g (Zeitsch. angew. Chem., 1888, page 680) closely resembled real coffee in appearance, but all the berries were precisely the same shape. Under the microscope, wheat-starch was detected, and Konig concluded that the article consisted of roasted wheat dough of low quality. E. Fricke (Zeitsch. angew. Chem., 1889, page 310) has described a factitious coffee containing caffeine, and apparently made from lupine-seeds (compare page 544). K. P o r t M e (Chem. Gentralhl., 1890, page 135) has described factitious coffee-beans sold under the name of " Kunst Kaffee." The following were the compositions of the samples referred to above : — Piyrthle. Konig. Fricke. Moisture, . Proteids, . Fat, Starch, sugar, gum, &c., . Cellulose, .... Caffeine, . Ash, .' . 1-46 per 13-93 , 3-86 64-01 , 15-83 0-07 , 2-53 cent. 5-14 per cent. 10-75 „ 2-19 76-76 „ 3-96 „ 1-20 *'„ (Analysed after dry- ing.) 17-90 per cent. 2-03 10-83 "*„ 0-94 „ 2-27 „ 101-63 per cent. 100 00 per cent. 100-00 per cent. Matter soluble in water, . 21-53 per cent. 29-28 per cent. 24-85 per cent. R. W 1 f f e n s t e i n (Zeitsch. angew. Chemie, 1890, No. 3) has described two varieties of factitious coffee, respectively known in IMITATION COFFEE. 537 OermaDy as Domkaffee and Allerweltkaffee. Both preparations were entirely destitute of caffeine. One consisted practically of chicory, while the other contained large quantities of lupines. From the latter specimen Wolffenstein isolated a brown colouring matter having the spectroscopic and chemical characters of Cassella-hrown. It was soluble in alkalies and in water, but was completely precipitated from its solutions by hydrochloric acid. Fourteen grammes of the sample extracted with water and pre- cipitated with acid yielded 1*67 gramme of the colouring matter (!). Factitious coffee-beans are, with very rare exceptions, heavier than water, while genuine roasted beans are invariably lighter, unless much over-roasted. In taking the specific gravity, twenty beans should be immersed in brine, which is then diluted with water till ten of the beans float and the remainder sink. The result shows the average density ; but individual factitious beans often vary considerably from the mean. In genuine coffee-beans a portion of the fine membrane or " parchment " with which the berries were invested will almost always be found adhering in the cleft. The microscopic structure of the bean, as seen in a thin section, or of the powder affords a certain means of recognising its nature. Most factitious beans contain starch, which is entirely absent from genuine coffee. Ohicory and other roots are readily recognisable by the microscope. The methods used for the examination of ground coffee may also be applied. Dangway beans, the seeds of Cassia tora or C. occidentalism abundant in British Burmah, have been prepared and patented as a substitute for coffee {Eng. Pat., 15,564, 1888). In Germany, the ground and roasted seeds have been sold under the name of "Mogdad coffee," and it is said that a smaller proportion than 20 per cent, in coffee cannot be detected either by the taste or the appearance of the sample. Dangway beans leave about 10 per cent, of ash on ignition, and have a characteristic microscopic appearance which has been described and illustrated by A. Wynter Blyth {Food ; Composition and Analysis). They sink very rapidly in water and colour brine more intensely than do coffee beans. Dangway beans contain a tannin distinct from caffetannic acid. They are destitute of caffeine, but 0. H e h n e r has de- tected a minute quantity of some other alkaloid. The use of Mussaenda Borhonica seeds, to be mixed and roasted with coffee-beans or entirely substituted for them, hai? also been patented {Eng. Pat, 14,945, 1888).^ ^ Investigations at Kew Gardens show the supposed Musscenda seeds to be •really those of Gcertnera vaginata. They contain no caffeine. 538 COMMERCIAL CHICORY. The beans of a species of Phaseolus are reported by E. F r i c k e to be roasted, ground, and sold as " Congo coffee." The berries are very large — 214 filling a 100 c.c. measure — and of shining black colour. The infusion is very astringent and contains no caffeine or other crystallisable alkaloid. To distinguish lupine-seeds from coffee-beans, Hager treats 3 grammes of the powdered sample with 20 c.c. of water and filters after half an hour. The filtrate from genuine coffee will be feebly yellow and not taste in the least degree bitter, while in the presence of lupine-seeds a marked bitter taste will be observed. Ground Coffee. Besides the foregoing sophistications and substitutions of the coffee-bean, ground coffee is liable to various adulterations.^ Some of these can be tolerated when practised in moderation, provided that the fact and proportion of admixture are duly acknowledged ; but it must be remembered that all these additions, including chicory, the least objectionable and by far the most widely used,^ are destitute of the volatile oil and peculiar alkaloid which give to coffee its most valued pro- perties. The diminished consumption of coffee in England is doubtless largely due to the frequency and extent of its sophistications. ^ The late Dr Wm. Wallace, writing in 1884 {Analyst, ix. 42), names the following articles as used for adulterating coffee : — Chicory, caramel, dried and roasted figs, dried dates, date-stones, decayed ship biscuits, beans, peas, acorns, malt, dandelion root, turnips, carrots, parsnips, and niangold-wurzel. Damaged raisins are stated by Albert Smith to be used together with chicory for making French coffee. 2 CoMMEKCiAL Chicory is prepared from the root of Cichorium iritybits, which is cut into slices, kiln-dried, and then roasted in the same manner as coffee, usually with the addition of a small proportion of fat of some kind. The preparation and use of roasted chicory appears to have originated in Holland about 1750. A. Mayer {Bied. OerUral., 1885, page 828) gives the following as the composition of three samples of Dutch chicory root : — Water, 72 '00 to 77*3 per cent.; albuminoids, 1*1 ; fat, 0*2; inulin and other non- nitrogenous matters insoluble in alcohol, 12-00 to 17 '3 ; crude fibre, 1'40 to 1-8 ; sugar, &c., 5*60 to 6*0 ; bitter extract, 0*05 to 0*15 ; and ash, 1*40 to 1 '9 per cent. Mayer found the bitter substances extracted by chloroform to be soluble in water and alcohol, insoluble in ether, and absorbed by bone- charcoal. They were decomposed by boiling with dilute sulphuric acid, but did not by such treatment yield any substance capable of reducing Fehling'a solution. A. Petermann {Bied. Central. , 1883, page 843) gives the following results of analyses of two samples of roasted chicory, one of which was coarsely and the other finely ground. The ash was somewhat higher than usual, but was perfectly white. The fat shown was probably not all natural to the CARAMEL IN COFFEE. 5m The chief adulterations likely to be met with in ground coffee are: — (1) Mineral matters; (2) roots, such as chicory, dandelion^ turnip ; (3) seeds and seed-products, such as beans, acorns, and cereals ; and (4) saccharine matters, such as caramel and roasted dates and figs. In Bulletin No. 29 of the Laboratory of the Inland Eevenue Department, Canada, the chief analyst, T. Macfarlane, states that : — "There are, moreover, large quantities of a substance imported under the name of essence of coffee, for adulterating pur- poses, which is a species of burnt sugar, and, from its containing dextrin, is probably made from some of the bye-products of the glucose factories. It costs in New York and Philadelphia from 3 to 5 cents per lb. As it possesses no organic structure it is apt to be overlooked in the microscopical examination. It contains about 75 per cent, of matter soluble in water, which has great colouring power, and a little of it is capable of imparting a strong brown coffee colour to water." Caramel, when added as such, may often be distinguished under a low microscopic power by the jet-black colour of the particles. These dissolve easily in water with intense brown colour, and the solution has a bitter taste. A factitious caramel is now manufactured by adding to glucose about one-eighth of its weight of a brown coal-tar dye, naphthol-hrown. A useful preliminary test for ground coffee consists in gently strewing some of the powder on the surface of cold water. The oil contained in coffee prevents the particles from being readily wetted by the water, thus causing them to float. Chicory and the chicory, as the proportion recorded is largely in excess of that found by other observers. The water also is much above the usual proportion in recently roasted chicory (5 to 7 per cent.), and the albumenoids below the usual rang& (8-75 to 11-50.— 0. Hehner). Coarse Grains. Fine Powder. Water (lost at lOO'-lOS" C), Glucose, ... Dextrin ; inulin, . . . Albuminoids, Colouring matter and bitter extractive, . Ash in soluble portion, Ash in insoluble portion, Albuminoids, Fat, Cellulose, 16-28 26-12 9-63 3-23 16-40 2-58 4-58 •15 5-71 12-32 16 -96% 23-76 1 9.31? Soluble in > hot water 17-591 2-55/ b-S9\ 2-98 Insoluble in >- hot water 3-92 =26-14. 13-37^ 540 DETECTION OF CHICORY. majority of coffee adulterants contain no oil, and their caramel is very quickly extracted by the water, with production of a brown colour, while the particles themselves rapidly sink to the bottom of the water.^ On stirring the liquid, coffee becomes tolerably uniformly diffused without sensibly colouring the water, while chicory and other sweet roots quickly give a dark brown, turbid infusion. Eoasted cereals do not give so distinct a colour. According to A. Franz (Arch. Pharm., [5], iv. 298), if 2 c.c. of a 10 per cent, infusion of coffee in boiling water be treated with 0*3 c.c. of a 2J per cent, solution of cupric acetate, and the liquid filtered, a greenish-yellow filtrate is obtained. If chicory be simi- larly treated, a dark red-brown filtrate results, the colour of which changes on standing. Ten per cent, of the adulterant can thus be detected. The colour of an infusion of chicory is said to remain unaltered on addition of a solution of ferric chloride or sulphate, while the brown colouring matter of coffee infusion turns green, and is par- tially precipitated as bluish-green flakes. In an infusion of mixed chicory and coffee, the reagent forms a precipitate, and leaves the liquid more or less brownish-yellow. The deposition of the pre- cipitate is facilitated by rendering the liquid slightly alkaline by ammonia (Dingier^ s poly t. Jour., ccxi. 78). Albert Smith (Pharm. Jour., [3], xi. 568) recommends, for the detection of chicory in coffee, that 10 grammes of the sample should be boiled with 250 c.c. of water, and the liquid strained and precipitated with a slight excess of basic lead acetate. On allowing the precipitate to settle, the supernatant liquid will be colourless if pure coffee has been under treatment, but in presence of chicory will be coloured to a greater or less degree according to the proportion present, which can be estimated from the depth of tint by a process similar to that of nesslerising water. The three foregoing tests are occasionally of service for the examination of infusion of coffee when the solid article is not available, but they cannot be regarded as so satisfactory as the actual recognition of the adulterant by the microscope. The great majority of seeds likely to be met with in coffee contain a notable quantity of starch. This is true of beans, peas, acorns, and all cereals and products therefrom. Hence if starch be absent, the freedom of the coffee from all this class of adulterants is certain. If present, the nature of the admixture can usually ^ If a funnel be used for the above test, the sunken particles may be readily let out and examined under the microscope. DETECTION OF STARCH IN COFFEE. 54] be ascertained by a microscopic examination of the prepared sample.^ For the detection of starch, the author boils the coffee for a few minutes with about 10 parts of water. When the liquid has become perfectly cold, some dilute sulphuric acid is added, and then a strong solution of permanganate of potassium dropped in cautiously, with agitation, till the colouring matter is nearly destroyed, when the liquid is strained or decanted from the dis- soluble matter. On now adding a solution of iodine to the solution, a blue coloration will be produced if any starch be present. As little as 1 per cent, can be readily detected in this manner.^ Some operators employ animal charcoal for decolorising the coffee infusion before testing for starch. The addition of starch- holding adulterants to coffee, in the author's experience, is rare, but in the United States and Canada is very common, the adulterants there found including wheat-flour and bran, buck- wheat, barley, maize, peas, pea-hulls, &c.^ The insoluble matter remaining after treating the coffee with water and decolorising with permanganate can be advantageously examined under the microscope for chicory and other non-starchy additions, the structure of which is more readily observed after the removal of the colouring matter. F. M. Rimmington {Pharm. Jour.^ [3], xi. 529) recom- mends, for the removal of colouring matter, that the sample of coffee should be boiled for a short time with water containing a little carbonate of sodium. After subsidence, the liquid is poured off, the residue washed with water, and then treated with a weak solution of bleaching powder until decolorisation is effected, which usually occurs in two or three hours. The real coffee will then form a dark stratum at the bottom of the beaker, and the chicory a light and almost white stratum floating above it, and showing a clear and sharp line of separation. ^ For this purpose the coflfee should first be exhausted with ether to remove fat, and then treated with methylated spirit to dissolve the colouring matter. In the residue, the starch and other structures will be readily perceptible. ^ A certain famous sample of coffee alleged to contain acorns gave the author no reaction by the above test, but after the addition of 2 per cent, of roasted acorns the test showed the presence of starch very clearly. ^ In 1875 a large seizure was made in the east of London of a mixture of 10 per cent, of coffee with 90 of roasted acorns. Roasted acorns were first placed before the English public as " Pelotas coffee," and subsequently as " coffee surrogate," but the manufacture of both these preparations was stopped by the excise. 542 DETERMINATION OF CHICOKY. Under the microscope, chicory is readily recognised by the peculiar dotted appearance of the vessels, often occurring in bundles, and by the characteristic appearance of the large cells. Dandelion, turnips, and other sweet roots present a close similarity to chicory, and can only be safely distinguished therefrom by careful microscopic comparison of the sample with the actual roots in question. The microscopic appearance affords the only certain means of identifying chicory and other roots in coffee, and the same state- ment applies to saccharine fruits, such as roasted figs, dates, raisins, &c.^ The nature of an adulterant of coffee having been ascertained by the aid of the microscope or other means, an attempt may be made to deduce the proportion present from the chemical composi- tion of the sample. When only one adulterant is present, this may sometimes be effected with a fair approximation to accuracy ; but even in the case of chicory it is not always possible to ascertain the proportion within a somewhat wide limit.^ For ascertaining the proportions of adulterants in coffee, the only chemical distinctions of any practical value are: — Certain constituents of the ash; the proportion of fat as extracted by ether or petroleum spirit; the proportion of aqueous extract, ^ Printed descriptions of microscopic characters are of little value, and drawings are often misleading. The adulterants of coffee are best examined as transparent objects under a moderate power, and, except where starch is to be identified, by unpolarised light. 2 What can be done in this manner, and the errors liable to occur in practice with deficient methods or imperfect manipulation, is apparent from the following figures obtained in 1882 by various analysts to whom exactly similar samples of mixed coffee and chicory of known composition were submitted {Analyst, vii. 76):— Actual percentage of \ Chicory in sample, . f Percentage of Chicory reported. Somerset House'* (Referees), ^ A, . 10 per cent. Not more than 2J per cent. 7 per cent. 7 „ 5 to 10 per cent. 16 per cent. Genuine. ! /Upwards of 10 ; \ per cent. per cent. Not less than 35 per cent. 31 per cent. 32 „ 25 „ 35 „ 31 Upwards of cent. per 37i per cent. Not less than 48 per cent. 38 per cent. 34 „ 50 „ 47 „ 50 „ Upwards of 40 per cent. ADULTERANTS OF COFFEE. 543 as deduced from its weight or the specific gravity of the solution ; the colour of the infusion; and the proportion of c a f f e i n e in the sample. In all cases of importance two or more of these methods should be employed. A. Smetham {Analyst, vii. 73) obtained the following range of figures by the analysis of seven samples of roasted coffee, repre- senting typical commercial qualities : — Moisture (lost at 100° C), Oil (ether extract), Crude fibre, ^ . ,, ,, in sample dried at 100° Cellulose, Nitrogen, Total ash, . . , Soluble ash, . Ratio of total ash to soluble, . 1*59 to 3*89 per cent. 10-13 ,, 12-13 „ 70-84 „ 74-60 „ 73-71 „ 75-70 „ 26-34 ,, 34-40 „ 2-14 „ 2-38 „ 4-08 „ 4-63 , 3-14 ,, 3-60 „ 100 :72 „ 100:82 „ The following analyses by C. Krauth {Ber., xi. 277; Jour. Chem. Soc, xxxiv. 449) give some comparative figures for coffee and its more probable adulterants. Except in the case of the last column, the results apply to the substances previously dried at 100° :— Ash. Fat. Sugar. Insol. in Water. Moisture in IJndried Substance. Pre- existent After 1 in Boiling Water, with 1 Acid, i Coflfee, roasted, five 1 samples, . . / 4-19 to 6-38 11-76 to 15-6 }-0-2 „,.„q/ 22-47 2*2^1 to 25-21 74-79 to 77-63 1-47 to 4-37 Chicory, roasted, . 10-83 1-15 23-40 22-14 65-42 34-58 4-30 Chicory, unroasted, Rye, roasted, 5-35 2-43 43 1-68 23-84 Not de- 78-71 termined. 75-37 31-92 21-28 68-07 6-89 0-28 Wheat, roasted, 1-80 2-75 ... 52-65 47-35 ... Coffee, with 10 per\ cent, rye, . . / 4-31 14-16 •19 29-65 25-98 74-46 2-15 Coffee, with 10 per\ cent, wheat, . / 5-10 12-55 2-30 23-15 30-63 1 69-36 2-30 1 The "crude fibre" was determined by boiling 2 grammes of the sampk with three successive quantities of water, and washing the residue on a counterpoised filter till the washings were colourless, when it was dried at 100° C. and weighed. 644 ADULTERANTS OF COFFEE. The following analyses by Konig show the composition of C(Ttain adulterants of coffee : — Chicory. Figs. Acorns. Rye. Water, 1216 18-98 12-85 15-22 Nitrogenous matters, . . . . 6-09 4-25 6-13 11-84 Fat, 2-05 2-83 4-61 3-46 Sugar 15-87 34-19 8-05 3-92 Other non-nitrogenous matters, 46-71 29-15 6-2-0 55-37 Cellulose, 11-00 7-16 4-98 5-35 Ash 6-12 3-44 2-12 4-81 Matters soluble in water, . 63-05 73-81 ... 45-11 (?) The following table shows the published results of analyses of coffee substitutes said to be manufactured respectively from acorns, rye, and barley :^ — - — " Acorn 1 Coffee." " Rye Coffee Substitute." "Barley Coffee." " Barley Coffee." Water, 12-85 2-22 3-45 6-41 Nitrogenous matters, . . . . 6-13 11-87 9-38 10-56 Fat. 4-01 3-91 3-25 1-04 Sugar, 8-01 ... > Starch, Dextrin, . • V 62-00 8-34 49-51 - 70-13 68-38 Other non-nitrogenous matters, i 9-83 J Cellulose, 4-98 9-78 4-25 10-56 Ash, . . 2-02 4-54 3-36 3-04 Matters soluble in water, . ... 61-33 31-20 34-37 Glucose formed by boiling with dilute sulphuric acid. } - ... 69-28 67-19 Moscheles and S t e 1 z e r have recently published complete analyses of several coffee substitutes (Ohem. Zeit., 1892, xvi. 281; Analyst, xvii. 154). One of these contained lupines (which they consider a very reprehensible addition), and another was destitute ^ The ' * acorn coffee " was analysed by Konig, who found from 20 to 30 per cent, of starch, and 6 to 8 per cent, of a variety of tannic acid. The " rye coffee substitute" was prepared by Behr Bros. The analyses of "barley coffee " are by C. K o r n a u t h. ASH OF COFFEE. 545 of coffee, but contained 0*31 per cent, of caffeine, due to the presence of powdered kola-nut. The ash of pure coffee is generally between 3 J and 4 J per cent., rarely, if ever, exceeding 5 per cent., and even when a considerable proportion of chicory is present it seldom rises beyond 6 per cent. Any notably higher proportion will indicate the presence of a mineral adulterant. The ash should be white, or nearly so, any marked red tint indicating an added compound of iron. The composition of the ash of coffee presents some marked differences from that of chicory, as is apparent from the following results of analyses by H. Ludwig {Arch. Fharm., [3], i. 482) and James Bell (Foods, ii. 46, 57). Coffee-beans. H. Ludwig. Coffee-beans, Eight Samples. J. Bell. Chicory Root, Eight Samples. J. Bell. Gneiss Soil. Limestone Sou. Deducting Si02 and Sand. Including Si02 and Sand. K20 ... 14-13 44-03 53-20 to 55-80 27-85 to 46-27 24-88 to 33-88 NaaO 5-84 5-85 Not detected 3-17 „ 16-90 2-04 „ 15-10 CaO 8-64 4-89 4-10 to 6-16 7-65 „ 10-81 5-00 „ 9-60 M9O 814 8-01 8-20 „ 8-87 5-33 „ 8-08 3-42 „ 7-22 FeaOs 16-54 1-96 0-44 „ 0-98 3-50 „ 8-29 3-13 „ 5-32 P2O6 18-65 10-54 10-15 „ 11-60 9-59 „ 12-61 6-65 „ 11-27 SO3 . 15-28 1-64 3-09,, 5-26 8-38 „ 11-78 5-38 „ 10-53 CI . Trace 0-98 0-26 „ 1-11 5-03 „ 6-08 3-23 „ 4-93 CO2 . 8-34 21-24 14-92 „ 18-13 2-04 „ 4-60 1-78 „ 3-19 SiOa 1-65 0-37 0-00 „ 0-45 2-61 „ 12-75 Sand None None None ... 8-08 „ 23-10 T .. J • _ J?. 3 •__ 1- i.--L1- i. _r ^_ J_ 14. Ludwig found in each case a notable amount of soda, a result which disproves Bell's improbable statement that this base is absent from coffee-ash. Ludwig's figures also show an enormous variation in the proportions of KgO, FcgOg, SO3, and COg, accord- ing to the nature of the soil on which the coffee-plant is grown.^ If the NagO in chicory-ash be calculated into its equivalent of KgO, and the figure thus found added to the actual KgO, the per- centage is not greatly different from the proportion of potash found 1 The sample of coffee from a gneiss soil must be regarded as highly abnormal. In the wide experience of the author the ash from genuine coffee has never been observed to have a red colour, as would be the case with the ash of a. specimen containing a considerable proportion of iron. VOL. III. PART II. 2 M 546 ASH OF COFFEE. by Bell in coffee-ash. The proportion of oxide of iron is notably greater in chicory than in coffee. Hence chicory-ash always has a red tinge which is absent from the ash of genuine coffee. A notable difference is observable in the proportions of COg and CI, and a very wide distinction in the figures for sand and silica. In only one of the eight samples of coffee did the silica even approach 0*5 per cent., and in another portion of the same coffee, which was properly screened before roasting, the silica of the ash fell to nil. In consequence of the large proportion of potassium carbonate in coffee-ash, the percentage of the total ash soluble in water is much greater than in the case of chicory-ash, and attempts have been made to utilise this fact for ascertaining the proportion of chicory present in mixtures of the two. Thus the author found from 60 to 85 per cent, of the total ash of coffee to be soluble in water, whereas on an average only 34 per cent, of the total ash of chicory was soluble in water. But this proportion is gravely affected by the proportion of actual sand which may be present. This varies in commercial chicory from a trace up to 4*5 per cent., which difference is quite sufficient to invalidate deductions based on the ratio of the total to the soluble ash. By comparing the soluble ash with the total ash minus sand and silica, somewhat more reliable results are obtained, but at best the method is only "Capable of affording a rough indication of the proportion of chicory present. It may, however, serve to point to the presence of a foreign ingredient, which can then be identified and determined by other means. The following ash-analyses, by J a m e s B e 1 1, are interesting in this connection : — Lupins. Acorns. Maize. Parsnips. Dandelion Root. K20 . . . 33-54 54-93 30-74 56-54 17-95 NagO . . 17-75 0-63 Not found Not found 30-95 CaO . 7-75 6-01 3-06 6-85 11-43 MgO . 6-18 4-32 14-72 6-49 1-31 FeaOs . . 0-54 0-84 0-53 1-27 P2O6 . . . 25-53 11-15 44-50 13-84 n-21 SO3 . . . 6-80 4-79 4-13 4-07 2-37 ca . . . 211 2-51 0-50 2-09 3-84 CO2 . . . 0-56 13-69 ... 11-44 6-21 SiOa, &c. . 0-87 1-01 1-78 0-57 11-26 101-09 99-58 100-27 102-42 97-80 The following centesimal figures refer to the ash of other roots :— by Way and Ogston DENSITY OF COFFEE INFUSION. 647 Turnip. Beet. Carrot. FeaOa . . . CI ... CO2 . . 0-14 to 0-66 3 „ 5 9-5 „ 15 0-52 to 3-74 85 „ 30 15 „ 21-6 0-59 to 1-66 3 „ 4-6 15 „ 19 The fat of co£fee is tolerably constant in amount, and hence the proportion serves as a useful indication of the amount of certain admixtures. Thomas Macfarlane, Head Chemist of the Inland Revenue Department, Ottawa, informs the author that the petroleum-ether extract from previously dried coffee ranges from 10 to 12 per cent. Only one sample out of nearly fifty examined showed less than 10, and no sample gave as much as 13 per cent., although 12J per cent, was reached in a few instances. Chicory yields about 1 per cent, when similarly treated, and three samples of roasted barley gave from 1*31 to 1'54 per cent. The aqueous extract of coffee is remarkably constant in amount, and is very little affected by variations in the roasting. Instead of weighing the actual extract, Graham, Stenhouse and Campbell {Jour. Chem. Soc.,ix. 38) determined the specific gravity of the aqueous infusions of coffee and various roasted vegetable matters. Their method was to treat the roasted sub- stance with ten times its weight of cold water, raise the liquid to the boiling-point, and observe the density of the filtered liquid after cooling to 60° F. ( = 15-5° C). The foUowing is a classified arrangement of their results : — Specific Gravity Specific Gravity Substance. of 10 per cent. Substance. of 10 per cent. Infusion. Infusion. COFFBE :— Roots :— Mocha, 1008-0 Chicory.Yorkshire, 1019-1 Neilgherry, 1008-4 „ English, . 1021-7 Plantation Ceylon, 1008-7 „ Foreign, . 1022-6 Java, . 1008-7 „ Guernsey, 1023-3 Jamaica, 1008-8 Average, 1021-05 Native Ceylon, . 1009-0 Parsnips, 1014-3 Costa Rica, . 1009-0 Carrots, 1017-1 Costa Rica, . 1009-05 Turnips, 1021-4 Average, . 1008-7 Dandelion, . 1021-9 Red beet, . 1022-1 Leguminous Seeds:— Mangold wurzel, . 1023-5 Lupins, 1005-7 Peas, . 1007-3 Cereal Products :— Beans, . 1008-4 Brown malt, 1010-9 Black malt, . 1021-2 Miscellaneous :— Rye meal, . 1021-6 Spent tan, . 1002-1 Maize, . 1025-3 Acorns, 1007-3 Bread raspings, . 1026-3 548 DENSITY OF COFFEE INFUSION. These results show a marked distinction between cofifee, legu- minous seeds, and acorns on the one hand, and cereal products and chicory and other roots on the other. Unfortunately, with the ex- ception of chicory and coffee, they apply merely to single speci- mens of each kind of substance. Experiments made in the author's laboratory gave a mean density for coffee-infusions precisely identical with that obtained by Graham, Stenhouse and Campbell (1008"7). Operating as they prescribe, however, there is always a suspicion that the exhaustion is incomplete, especially in the case of genuine coffee which has not been very finely ground. Hence in a series of experiments made in the author's laboratory, the sample of coffee was well boiled with 10 parts of water, the solution filtered, and the residue washed with hot water till the filtrate measured 10 c.c. for every 1 gramme of the substance employed. Operating in this manner, the infusions from fourteen specimens of ordinary commercial roasted coffee (ground in the laboratory) were found to have a specific gravity ranging from 1006*8 to 1008*5, with an average of 1007-9 1 (Analyst, v. 1). J. Skalweit has shown that the specific gravity of the aqueous infusion is not sensibly affected by the extent to which the coffee has been roasted. By the exhaustion-process, the author obtained the following results from samples of commercial chicory (undried) : — Specific Gravity of] Yorkshire Chicory, under-roasted, ,, ,, (same sample), highly roasted, Chicory of unknown origin, .... 10 per cent. Infusion. 1025-9 1019-0 1021-1 1020-0 1023-4 1021-9 It is evident that the density of chicory infusions varies much more than that of coffee, a fact which prevents the method from furnishing more than an approximate determination of the propor- tion of coffee and chicory in a mixture of the two. A sharper result may be obtained by previously drying the sample at 100°, ^ This figure is somewhat lower than the average of Graham, Stenhouse, and Campbell's experiments, which tends to show that they effected practically perfect exhaustion. The difference is not improbably due to a slight loss by evaporation when the infusion is made by raising the liquid to the boihng- point, instead of boiling thoroughly and making the infusion up to a definite measure after cooling. 0. H e h n e r has met with a genuine coffee giving an infusion-density of 1010-2. DETERMINATION OF CHICORY. 649 and hence eliminating the somewhat serious error due to varying l)roportions of moisture. Adopting 1024 as the normal gravity of the infusion of dried chicory and 1009 as that of dried coffee, the percentage of real coffee in a mixture of the two will be found by the following equation, where d is the specific gravity of the 10 per cent, infusion and C the percentage of coffee in the sample: — C- (1024 -<^) 100 15 A. M^Gill {Trans. Royal Soc. Canada, 1887) finds that the density of the infusions of coffee and chicory is materially affected by the fineness of the powder, the time occupied in heating the decoction to boiling, and the time during which the boiling with water is continued. He recommends that a weight corresponding to 10 grammes of the moisture-free sample should be boiled with 100 c.c. of distilled water in a flask fitted with a reflux condenser. The heat is adjusted so that ebullition commences in ten to fifteen minutes, and the boiling is continued exactly one hour, when the flame is removed, and after fifteen minutes' rest the liquid is passed through a dry filter. The average density of a 10 per cent, decoction of pure coffee thus prepared was found to be 1009*86 at 62°, the mean number for chicory decoction (three samples) being 1028*21 at the same temperature, or a difference of 18*35.^ From these results the following formula may be deduced : — (1028-21-(Zat62°F.)100 18-35 ^ Thos. Macfarlane, Chief Analyst in the Inland Revenue Laboratory, Ottawa, has communicated to the author the following results, obtained by the application of M^Gill's method for ascertaining the infusion-density and actual determination of the soluble extract. This last determination was made by thoroughly extracting the dried sample with petroleum ether, and then treating the redried substance with boiling water. Instead of evaporating the solution, the insoluble matter was redried and weighed, the loss showing the ** water extract " : — Sontas Coffee, Mocha Coffee, Java Coffee ,, with 10 per cent. Chicory, ,, 20 Chicory, Water Extract. 22-44 21-92 26-42 25-90 30-75 37-40 43-36 49-84 53-82 60-34 65-93 71-41 77-73 Infusion Gravity »t 62° F. 1009-78 1009-73 1011-58 1013-44 1015-28 1017-08 1018-66 1020-48 1022-70 1024-15 1026-42 1028-32 550 DETERMINATION OF CHICORY. It is evident that the specific gravity of the aqueous infusion is really a function of the solid matter dissolved by the water, and a close approximation to the percentage of the latter can be obtained by dividing the difference between the solution-density and 1000 by the number 0*375 or multiplying it by 2-67.1 Thus if a coffee-infusion have a density of 1009*0, the proportion of matter soluble in water will be 1009-0-1000-0 „, ^ . 0^376 24-0 per cent. The figures for soluble extract obtained by T. Macfarlane (Ottawa) by the analysis of 54 samples of commercial coffee ranged from 21*5 to 26*5 per cent., with an average of about 24 per cent.^ The samples were dried at 100°, deprived of fat by treatment with petroleum ether, re-weighed, and then exhausted with water. Instead of evaporating the infusion and weighing the soluble extract, the insoluble residue was dried and weighed, and the loss gave the soluble extract. A. Smetham has also proposed to wash, dry, and weigh the insoluble matter left on the filter. Alfred E. Johnson states the soluble extract from previ- ously dried (roasted) coffee to be very constant at 24 per cent., and the extract from dried chicory to average 70 per cent.,^ and on these figures bases the following process for the analysis of coffee mixtures. The ground coffee is dried at 100° C. and 5 grammes weight of the moisture-free sample boiled for fifteen minutes with 200 c.c. of water. After settling for a few minutes, the liquid is poured off through copper wire-gauze or coarse muslin into a 250 c.c. flask. The grounds are boiled with 50 c.c. of water for five minutes and the liquid strained as before. The contents of the flask are cooled, made up to 250 c.c, agitated, and poured on to a dry filter. Fifty c.c. of the filtrate, rejecting the first portion (equal to 1 gramme of the dry sample), is then evaporated in a flat dish over boiling water, ^ This factor is deduced from the known solution-densities of caramel and the carbohydrates. J. Skalweit {Rep. Anal. Ghem., 1882, page 227), as the result of direct experiment, gives the following data: — At 17 '5" C, I'OOl sp. gr. of 20 % infusion represents 0'36 extract per 100 c.c. 1-115 ,, „ „ 27-24 „ 1'235 „ „ „ 48-25 2 The purity of some of these samples was doubted, and Macfarlane considers 22*0 per cent, to represent more accurately the usual proportion of extract yielded by genuine coffee. ^ 0. Hehner found a lightly-roasted chicory (dried) to give Ql '1 per cent, of soluble matter, and an infusion-density of 1024*4, while a highly-roasted sample had an infusion-density of 1019, and yielded only 54*1 per cent, of extract. COLOUR OF COFFEE INFUSION. 551 and the residue (representing the extract from 1 gramme) dried in the water-oven and weighed. Then : — 100 (70 -per cent, of extract found) . „ „» . ^ .X ^ — percentage of coffee m sample. The results thus yielded by coffee and its principal adulterants are given on pages 543, 544. The tinctorial poicer of the infusion was suggested by Graham, Stenhouse and Campbell {Jour. Chem. Soc, ix. 36) as a means of determining adulterants in coffee. They found that the depth of colour of the liquid obtained by infusing coffee and its adulterants in 2000 times their weight of boiling water varied remarkably, caramel giving about seven times and chicory about three times as deep a colour as coffee.^ But their experiments showed that four different samples of pure coffee varied in tinctorial power between 143 and 183, as compared with caramel as 1000, and no doubt samples of chicory would be found to present at least as great difference in colouring power, according as they happened to be lightly or strongly roasted. Nevertheless the author found {Chem. News, xxix. 140) that the tinctorial power of an infusion of mixed samples of chicory was almost exactly three times that of an infusion of average or mixed coffee, and that different samples of chicory did not vary more than from 2*8 to 3'2 in colouring power when compared with the same sample of coffee. In order to estimate the proportion of chicory in a sample of coffee mixture, a standard mixture should be prepared by mixing together several representative samples of genuine ground coffee with an equal weight of mixed chicory.^ One gramme of this standard coffee mixture (containing 50 per cent, of coffee), and the same weight of the sample to be tested, are boiled for a few minutes with 20 c.c. ^ The following are the relative amounts of various roasted substances found by Graham, Stenhouse, and Campbell to impart an equal depth of colour to the infusion : — Caramel, . 1-00 Mangold wurzel, . 1-66 Black malt, 1-82 White tiirnjps, . . 2-00 Carrots, . 2-00 Chicory (darkest Yorks), 2-22 Coffee, . . 5-46 to 6-96 White lupin-seed, . lO'OO Beans and peas, . IS-SS Spent tan, . , . 33-00 Brown malt, . .40-00 Parsnips, . . 2-50 Maize and rye, . 2-86 Dandelion root, 3-33 Red beet, . . . 3-33 Bread raspings, . 3-64 Acorns, . .5-00 2 If the standard coffee mixture be kept, it undergoes a change which modi- fies, even in a dry state, the colour of the infusion. A permanent standard of the right tint can be made by mixing solutions of ferric, cobalt, and copper sulphates in proper proportions. The yellowish-brown glass employed in Lovibond's tintometer for the colorimetric determination of carbon in steel can also be employed as a standard, if its value be previously ascertained. The tints are best observed by placing a piece of wet filter-paper behind the tubes while they are held up to the light. 552 CAFFEINE IN COFFEE. of water. The liquids are cooled and passed through a double filter, the insoluble portions being repeatedly boiled with fresh quantities of water till no more colour is extracted. The solution of the standard mixture is then made up with water to 200 c.c, and the solution of the sample to 100 c.c. Ten c.c. of this latter liquid is poured into a narrow graduated tube, and some of the standard solution into another tube of exactly equal bore. If the sample consists of pure coffee, the two liquids will now be of exactly similar tint ; but if chicory be present, the solution of the sample will be the darker, in which case water is gradually added till the tints are precisely equal. When this point is attained, the volume of the sample solution is observed. Every 1 c.c. of water added represents 5 per cent, of chicory in the sample. Thus if the liquid measure 17 c.c, the sample contains 35 per cent, of chicory. J. R. Leebody {Chem. News, xxx. 243) has described a similar method, but, instead of observing the colour of the solutions transversely, he dilutes the solution from 1 gramme of the coffee to 700 c.c. and observes the colour from above, as in nesslerising water. The observation of the infusion-colour is occasionally very useful as an indication of the presence of caramel added as such, since in that case the colour wiU be greatly in excess of the proportion of chicory or other adulterant as deduced by other methods. The caffeine of coffee is tolerably constant in amount, and hence its determination has been recommended by Paul and C o w n 1 e y (Pharm. Jour., [3], xvii. 565, 648, 821, 921) as means of estimat- ing the proportion of real coffee in a mixture. These chemists have shown (page 492) that most of the published methods for the determination of caffeine give results more or less below the truth, but that when the process recommended by them is adopted the proportion of caffeine isolated varies within comparatively narrow limits. This is especially the case if the roasted berries are dried at 100° before grinding them, as by this means the error due to variable proportions of water is eliminated, and the coffee can be obtained in a finer state of division, and hence be more perfectly exhausted. In fourteen commercial samples of coffee-berries, Paul and Cownley found the moisture to vary from 6'2 to lO'O per cent. After drying at 100° C. the caffeine ranged from 1-20 (in a coffee from Coorg)to 1*29 per cent, (found in coffee from several sources), except in Liberian coffee, which yielded 1-39 per cent. On the basis of 1-3 per cent, of caffeine in genuine coffee, adopted by Paul and Cownley, the proportion of real coffee in a mixture will be found by dividing the percentage of alkaloid found into 130. It would be safer to adopt the number 120 instead of 130, and in using the method great care is necessary to effect the isolation of COFFEE EXTRACT. 553 the whole of the caffeine. To ensure this, the sample must be in very fine powder, the exhaustion by alcohol of the mixture of coffee with lime or magnesia must be proved to be complete, and the agitation of the aqueous liquid with chloroform must be repeated until no more alkaloid is extracted. Although, when taken alone, any one of the foregoing methods of examining coffee is liable to lead to determinations of the pro- portion of adulterants somewhat wide of the truth, by the combined use of several a fairly accurate deduction can be made. In certain rare cases, additional information may be obtained from the deter- mination of the fatty matters, the alkalinity of the soluble ash, and the proportion of nitrogen. Coffee Extracts are prepared with very limited success by subjecting roasted coffee to treatment with boiling water or steam, and adding the volatile products to the aqueous extract. The product is deficient in caffeine, and does not contain all the extractive matter of the coffee ; nor, when diluted with the appro- priate amount of water, is the colour the same as that of the freshly-prepared liquid. To remedy this defect caramel is added, together with strong alcohol as a preservative. In one patent, addition of chicory and sugar is prescribed. The following results were obtained by A. D o m e r g u e by the examination of six samples of coffee extract : — Water. Extract dried at 100° C. Caflfeine. Ash. A, . . . 86-3 13-7 per cent. 0-106 per cent. 0-61 per cent. B, . . . 82-4 17-6 ,, 0-105 „ 0-79 „ C, . . . 58-99 41-01 „ 0-060 „ 4-30 „ D, . . . 72-8 27-2 „ 0-040 „ 3-10 „ E, . . . 69-9 30-1 „ 0-050 „ 1-40 „ F, . . . 80-74 19-26 „ 0-096 „ 1-83 „ Samples A and B were prepared in the laboratory. C, D, and E were coloured with caramel. Domergue regards the proportion of caffeine as the best indication of the value of a coffee extract. Of three samples of " coffee extract " examined by G. L. Spencer, one was destitute of caffeine, but contained cereals and other starchy bodies; a second contained 1*19 per cent, of caffeine, or about as much as ordinary coffee ; and a third was a mixture of coffee extract with milk and sugar, and contained 0*72 per cent, of caffeine. Very notable proportions of tin and copper were detected in these preparations. 554 KOLA NUTS. Kola -nuts. ^ The Gourou or Kola-nut, from a tree belonging to the family Sterculiaceoe, is chewed and used for preparing a beverage in Western Africa, by the negro inhabitants of the West Indies, Brazil, &c. From the nut of Sterculia or Cola acuminata, the female or true Kola, H e c k e 1 and Schlagdenhauffen {Pharm. Jour., [3],, xiv. 584) obtained the following products : — Caffeine, . . 2 '3 48 per cent, lilxtracted by J Theobromine, . 0'023 Chloroform:— I Fats, . . . 0*585 Tannin, . . 0027 ' Tannin, . . 1-591 Extracted by J Kola red, . . 1*291 Alcohol: — I Glucose, . .2-875 „ Salts, . . 0-070 (Starch, . . 33754 Gum, . . 3040 „ Colouring matters, 2*561 „ unaissoivea: — n Proteids, . . 6-761 ,, J CeUulose, . . 29830 „ I Ash, . . 3-325 „ I Water, . . 11919 Accordmg to E. Knebel {Apoth. Zeit., 1892, p. 112), kolar nuts contain a glucoside, k o 1 a n i n, which on boiling with water,. or by treatment with dilute acids, splits up into caffeine, glucose, and k o 1 a - r e d, C-^fl^^{OH.)i:^. This last product is an extremely unstable substance, taking up oxygen during the drying of the nuts, with separation of water and formation of gallotannic acid, Ci^HjqOq. It is stated that fresh kola- nuts have a greater physiological activity than when dried, as in the former condition the kolanin has not undergone the degenera- tion which destroys it and renders the caffeine insoluble. M n a r n and P e r r o n e state that powder and extract of kola-nuts have a far greater power of diminishing the elimination of phosphates and nitrogen than caffeine alone has. Kola-red has ^ Kola-nuts are oblong, three forming a ball fully 2 inches in diameter, and resembling a very large horse-chestnut. The individual nuts have a rugged, dark brown surface. Inside they are light brown, becoming rusty on exposure, and tough as wood. When fresh the taste is first sweet, then astringent, and finally bitter. After drying the bitterness diminishes. Various other African plants yield seeds closely resembling the true Kola, but it is doubtful whether they contain caffeine. GUARANA. 555 a diminishing influence, but both it and caff'eine act better in their natural combination than separately. Caffeine has a diuretic action, whereas kola is anuretic. The drug prevents waste of brain as well as of muscular tissue. False Kola, Male Kola, or Kola Bitter, is the seed of Garcinea kola, a plant of the family of the Cruttiferce growing in Liberia and Central Africa. On extracting the seeds with chloroform, ether, and alcohol, no caff'eine is obtained, but only resins. One of these gives a violet coloration with ferric salts, while the other is dextro-rotatory and precipitated by tartar emetic and basic lead acetate. The physiological action of the extract of kola bitter is attributable to these resins. Guarana.^ This product occurs in the form of cylinders. It is an inde- finite mixture of various materials, of which the seeds of PaulUnia sorhilis appear to be the only constant and characteristic ingredient. It is prepared by the Guaranis, a tribe of half -savage Indians on the Upper Amazon. Its only interest is as a source of caffeine, of which it contains a notable proportion. Sten house obtained 5-04, and F. V. Green 5*05 per cent. E. R. Squibb found 4 '8 3 per cent. {Ephemef-is, ii. 615). J. H. Feemster (Pharm. Jour., [3], xiii. 363) obtained from 3*9 to 5*0 per cent, of caffeine from five samples of guarana. The alkaloid is readily isolated in a state of purity by boiling the substance with water and litharge for some hours, or until the liquid is colourless and the deposit settles readily, concentrating the filtered liquid, and agitating with chloroform. Cocoa and Chocolate. Cocoa is the seed of the tree Theohroma cacao and allied species growing wild in tropical America. It is cultivated in Brazil, Grenada, Trinidad, &c., and has been introduced into the East Indies and parts of Africa and Australia. The cocoa-seeds from diff'erent districts vary considerably in appearance and flavour, but do not present any sharp distinctions in chemical composition. The fruit of the cocoa contains from 25 to 40 seeds closely packed in the pulp, which is removed by subjecting the seeds to a process of fermentation for a few days. The pulp is then separated by hand, and the seeds placed in trays and dried slowly in the sun or by artificial heat, being turned over at intervals. The flavour 1 Throughout Brazil, and in all parts of South America where the prepara- tion is used, the word guaran& is universally accented on the last syllable^ and never pronounced guarana. 556 COMPOSITION OF RAW COCOA. of the cocoa is greatly dependent on the care and skill with which the operations of fermentation and drying are conducted. The process has been compared to the malting of barley, germination taking place and being subsequently arrested. It is alleged that the alkaloid is formed during the process of fermentation, but the statement requires confirmation.-^ When quite dry, the cocoa-seeds are ready for exportation, but before being used they are subjected to a gentle roasting, whereby the bitter taste is modified and the kernels are more readily separated from the shells or husks, which constitute from 8 to 14 per cent, of the entire seed. When separated from the husks the broken kernels are known as cocoa-nibs. K n i g has published analyses of eight samples of decorticated cocoa-beans and of the husks from the same specimens. The following figures show his average results : — Moisture. Nitrogenous Matters. 1 Fat. Starch. Cellu- lose. Ash. Cocoa-beans freed from\ shell, ..../" Cocoa-husks, 3-25 7-83 14-76 14-29 49-00 \ 13-31 6-38 3-68 14-69 3-65 7-12 The following analyses of raw cocoa are byBoussingault {Ann. Ghim. Phys., [5], xxviii. 433) : — Kernel. Kernel. Husk. Water, . , . Theobromine, . Albuminoids, Asparagin, . Fat, . . . Soluble cellulose, Starch and glucose, Gum, Tartaric acid,* . Tannin, . Ash, . . . Undetermined, . 7-6 3-3 10-9 trace 49-9 10-6 2-4 2-4 3-4 0-2 4-0 5-3 11-6 2-4 12-9 53-0 } .1 } - 12-18t 14-26 3*9 12-12 6-05 * The presence of tartaric acid in cocoa has been confirmed by Weigmann, who found from 4*34 to 5-82 per cent, in the raw whole beans. To determine it, he neutralised the aqueous extract with ammonia, added calciimi chloride, redissolved the precipitate in hydrochloric acid, and reprecipitated with soda. t This proportion of water seems improbably high. ^ The author mclines to the opinion that the alkaloid of tea is in great measure a product of the decomposition of some more complex body, as has been proved to be the case with the caffeine of cola-nuts. It appears not improbable that the same may be true of the theobromine of the cocoa-bean. CONSTITUENTS OF COCOA. 557 According to A. H. Church {Foods, page 200), good cocoa- nibs contain: — Water, 5'0; albuminoids, 17'0; fat, 510; theo- bromine, 1'5 ; cocoa-red, 3*0 ; gum, &c., 10*9 ; cellulose and lignose, 8"0 ; and mineral matter, 3 "6 per cent. J. Bell gives the following as the composition of raw Trinidad cocoa-nibs: — Moisture, 5'23; fat, 50"44 ; starch, 4*20; alkaloids, 0*84 ; albuminous matters, soluble, 6*30, insoluble, 6*96 ; astringent principle, 6*71; cocoa-red, 2*20; gum, 2'17; cellulose, 6*40; in- definite insoluble organic matter, 5*80; and ash, 2*75 per cent. The following analyses of commercial raw cocoa, after removal of the husk, are by Eastes -and Terry {Pharm. Jour.^ [3], XV. 764):— Kind of Cocoa. Moisture. Fat. Theo- bromine. Ash, H3PO4. Caraccas, 4-75 53-65 1-08 2-76 1-36 Carupano, 5-04 47-38 0-87 3-69 1-39 Grenada, 6-59 47-12 1-42 2-81 0-91 Guayaquil 3-68 52-97 1-74 3-28 0-85 Para, 4-39 57-07 1-00 3-09 1-30 Surinam, 2-55 53-70 1-42 2-44 0-85 Trinidad (common), . . . . 5-62 45-71 105 2-79 0-89 Trinidad (fine, St Antonio), . . 4-72 53-57 1-94 2-70 1-15 The following analyses by C. Heisch (Analyst, i. 142) show the range of variation of certain of the constituents of commercial roasted cocoa-beans. The difference in the proportions of husk is due to the great variation in the thickness of the shells of cocoas from different sources : — Kind of Cocoa. Propor- tion of Husk. Eoasted Bean after Removal of Husk, ll 1 1 1 1^ Ash. Per cent. H II i JO Caraccas, 18-8 4-32 48-4 1-76 11-14 32-19 3-95 2-15 1-54 Trinidad (inferior), . 15-5 3-84 49-4 1-76 11-14 32-82 2-80 0-90 0-98 Surinam, .... 15-5 3-76 54-4 1-76 1114 28-35 2-35 0-80 1-23 Guayaquil, • 11-5 4-14 49-8 2 06 13-03 30-47 3-50 1-75 1-87 Grenada 14-6 8-90 45-6 1-96 12-40 85-70 2-40 0-60 1-3.T Bahia, . . . . 9-6 4-40 50-3 1-17 7-40 35-30 2-60 0-90 1-26 Cuba 12-0 3-72 45-3 1-37 8-67 39-41 2-90 0-95 1-13 Para, 8-5 1 3-96 54-0 2-00 12-66 26-33 805 1-40 1-00 658 CONSTITUENTS OF COCOA. J. Bell {Analysis and AduU&'ation of Foods) gives the foUow- m(T particulars respecting the composition and the ash of cocoa-nibs and husk : — Kind of Cocoa. Per 100 Parts of Cocoa. Per 100 Parts of Ash. i 1 3 SI ii 1^ .s P2O6. CO2. K2O. FeO. Guayaquil nibs, . 506 0-54 3-63 56-20 none 49-39 0-69 23-35 0-21 Surinam nibs, . 4-55 0-80 2-90 43-45 none 37-78 ' 3-31 28-00 0-38 Grenada nibs, 5-71 0-91 2-82 48-58 none 39-20 2-92 27-64 0-15 Finest Trinidad nibs. . 4-47 0-84 2-75 46-55 none 36-20 4-19 29-30 0-11 husks, . 10-19 1-36 8-63 54-92 5-91 17-17 1 10-80 37-89 0-63 In these analyses the figures for alkaloid are probably considerably below the truth. The ash of cocoa is distinguished by the small proportion of chlorides, carbonates, and sodium compounds contained in it, and by the great preponderance (3 or 5 : 1) of magnesia over lime. In Bell's analyses of cocoa-ash, no mention is made of the presence of copper. D u c 1 a u x proved this metal to be con- stantly present in cocoa. Galippe confirmed this, and found proportions varying from 0*0112 to 0'0292 grammes per kilo- gramme of cocoa. The greater part of the copper existed in the husks, and in inferior kinds of chocolate containing cocoa-husk in large proportion copper was occasionally present to the ex- tent of 0*125 gramme per kilogramme. The most important and characteristic constituent of cocoa is the alkaloid theobromine. A small proportion of caffeine is some- times present in addition. The recorded proportions of theo- bromine are very variable and generally untrustworthy. The method of determination has already been described (page 496). P. Troganowski {Archiv der Pharm., [3], x. 32 ; Jour. Chem. Soc, xxxii. 363) found from 1*2 to 4*6 per cent, of theobromine in cocoa, and concluded, from the result of a large number of experi- ments, that the proportion of alkaloid does not always bear a relation to the quality and value of the cocoa. This is probable, but the difficulty attending the accurate determination of theo-bromine in cocoa renders any deduction of the kind of very doubtful value. The fat of cocoa {Oleum Theobromatis, B.P.), sometimes called "cocoa butter," consists chiefly of stearin, and is fully CONSTITUENTS OF COCOA. 659 described on page 568. The proportion of fat present in cocoa- nibs, free from husk, varies only a few units on each side of 50 per cent., and hence is valueless for the discrimination of samples from different sources. The taste and aroma of cocoa are chiefly due to a volatile substance, probably an essential oil, which a]ipears to be developed by roasting, in the same manner as the caffeol of coffee (page 532). The tannin of cocoa also contributes to the flavour. The cocoa-red probably does not pre-exist in cocoa, but is a product of the oxidation of the tannin. If cocoa, from which the fat has been previously removed (by petroleum spirit), be ex- hausted with alcohol, and the solution treated with acetate of lead, a precipitate is produced, which, when suspended in water and decomposed by sulphuretted hydrogen, yields a clear and colourless filtrate ; but on evaporating this liquid, it acquires a bright red colour, and on taking up the residue with water, cocoa-red remains insoluble. Cocoa-red gives various coloured precipitates with metallic salts, the tints depending on the extent to which oxida- tion has occurred, and, apparently, on thf» variety of cocoa employed. P. Troganowski {Archiv. der Phari.c, [3], x. 32 ; Jour. Ghem. Sac, xxxii. 363) has described various colour-reactions yielded by the aqueous or alcoholic solutions of cocoa from various sources, but the value of the indications obtained is very questionable. The gum of cocoa closely resembles gum-arabic in appearance, and yields mucic acid on oxidation with nitric acid. It differs from gum-arabic in being strongly dextro-iotatoTj . The starch of cocoa is present in only moderate proportion, and the amounts recorded by some observers are probably in excess of the truth. The granules are small, round, and exhibit a central hilum. Under the microscope they are readily distinguished from the granules of added starches. Nitrogenous constituents of cocoa. G. W. Wigner (1878) showed that of the nitrogen of cocoa only a portion varying from 39 to 78 per cent, existed in a coagulable form (Analyst, iv. 8). The total nitrogen, as determined by combustion with soda-lime, ranged from 0'70 to 2'98 per cent., and that existing as coagulable albuminoids from 0*33 to 2*33 per cent. According to Wigner, of the nitrogen in a non-coagulable form, part exists as theobromine and a further portion as nitrates. Wigner argued from this that the value of cocoa as food had been over-estimated. Weigmann similarly found only 42 per cent, of the nitro- genous substances in cocoa to be digestible ; and S t u t z e r states that, in spite of apparently favourable conditions, due to the physical condition of commercial cocoa, a large proportion of the 560 MANUFACTURED COCOAS. nitrogenous constituents remains entirely indigestible. S t u t z e i classifies the nitrogenised compounds of cocoa as follows : — 1. Non-proteids ; substances soluble in neutral aqueous solution in presence of cupric hydroxide (theobromine, ammonia, amido-com- pounds). 2. Digestible albumin; insoluble in neutral aqueous solutions in presence of cupric hydroxide, but soluble when treated successively with acid gastric juice and alkaline pancreas extract. 3. Insoluble and indigestible nitrogenous substances. The following are the results of the analysis of four cocoa powders examined by S t u t z e t (Zeitsch. f. angeio. Chem., 1891, page 368) for the purpose of determining the effect of the process of manufacture on the chemical constituents. A was composed of 40 per cent. Ariba, 40 of Machala, and 20 of Bahia cocoa, and was manufactured by Wittekop & Co. without the use of chemicals. B is a sample of a well-known cocoa manufactured in Holland with the addition of potash.^ C and D are German cocoas, and, in Stutzer's opinion, were prepared by the use of ammonia : — A. D. Water, Fibre, Nitrogen-free extract, .... Total nitrogenous substances,!^ Tat Ash,2 1 Containing total nitrogen, .... Composed of :— Theobromine Ammonia, A.mido-compounds, Digestible albumin, Indigestible nitrogenous substances, . Containing nitrogen, . Proportion of total nitrogen indi-\ gestible, / a Containing : -Total P2O6 P2O5 soluble in water, . Ratio of total P2O5 to soluble. Ash soluble in water. Ratio of total ash to soluble. Per cent. 4-30 20-84 27-83 5-05 Per cent. 3-83 37-48 19 '88 30-51 8-30 Per cent. 6-56 39-99 20-93 27-34 5 18 Per cent. 5-41 36-06 19-25 83-85 5-43 100-00 100-00 100-00 100-00 3-68 1-92 0-06 1-43 10-25 7-18 1-15 31-2 3-30 3-95 1-73 1-98 0-03 0-46 1-25 0-31 7-68 10-50 9-19 7-68 1-47 1-23 14-5 31-2 3-57 1-80 0-33 1-31 7-81 8-00 1-28 85-8 1-85 1-43 100:77 3-76 100 : 74 2-52 0-50 100:19 4-76 100:57 2-14 0-74 100 : 34 2-82 100 : 54 2-05 0-77 100 : 37 2-76 100 : 49 ^An analysis of the ash of Van Houten's cocoa by Konig (in 1880) showed:— Total ash, 7'84; KgO, 3-52 ; CaO, 0-27 ; MgO, 0-81 ; PA. 1"84 COMMERCIAL COCOA. 561 Commercial Cocoa and Chocolate. In its simplest form, commercial cocoa consists of the roasted and husked seeds (" nibs ") ground to a paste or semi-fluid, and run into the form of cakes. Flake cocoa is sometimes made by passing the decorticated seeds through a particular kind of rollers ; but it is mostly made from the small particles containing much shell and germ, separated by the sieves. The term "cocoa" is sometimes misapplied to mixtures of real cocoa with sugar, &c. The practice is highly objectionable and has led to much confusion. It is better to describe all such cocoa mix- tures as chocolate, reserving the name cocoa for the unmixed article. All good cocoa preparations should be made from the cotyledons only, though the husks enter into the composition of many of the inferior kinds of cocoa and chocolate. In Germany, under the name of "cocoa-tea," and in Ireland as " miserables," cocoa- husks are an independent article of commerce,^ the infusion of which in boiling water is drunk after the manner of tea. The large proportion of fat in cocoa (averaging 50 per cent.) renders it impossible to manufacture a permanent preparation in the form of powder, without either removing a portion of the fat or diluting the material with some non-fatty matter, such as sugar, starch, or farina. Hence, there are two distinct types of "cocoa" known in commerce, namely : — "l. Preparations commonly called "coco a-e s s e n c e," or "cocoa-extrac t," consisting of ground cocoa-nibs, from which a part of the fat has been removed by heat and pressure. 2. Preparations to which sugar and, generally, some starchy material have been added. The sugar is usually sucrose (cane or beet sugar), but reducing sugars are sometimes present in notable quantity. Of the pure starches, arrowroot and rice starch are used in the better preparations, while wheat- and potato-starches and wheat-flour are also met with. Moeller also mentions acorn and rye flours, ground earth-nuts, and malt, to which M a c ^ adds almond-cake and sawdust. Any cheap vegetable material, capable of being reduced to fine powder, is liable to be used by unscrupulous per cent. Belohubeck(in 1888) found : —Total ash, 7 '88 ; and for 100 of total ash, KgO, 52*89 ; CaO, 1 '56 ; MgO, 10-45 ; P2O5, 24*91 ; CO2, 3*45 per cent. ^ In large cocoa manufactories the husks are sorted by sieves into several sizes. The largest are employed for infusion, and the finest, containing a con- siderable admixture of the kernels, are ground up with sugar and cacao-butter to produce a low grade of chocolate. The intermediate sizes are not readily applicable for either of the above purposes, and hence fetch a lower price than the coarsest and finest husks. They are employed for cattle-food, and at Hamburg are pressed for the extraction of cacao-butter. VOL. III. PART II. . 2 K 562 COCOA ESSENCE. cocoa manufacturers, but the better class of preparations which have acquired a reputation in the United Kingdom are free from any suspicion of such admixtures. A considerable addition of cacao-butter is made to some kinds of chocolate.^ The flavouring agents added to chocolate are most frequently vanilla and cinnamon. Artificial vanillin, nutmeg, cloves, mace, &c., are also used. In addition to the mechanical difficulty of manipulating undiluted cocoa containing all its natural fat, it is stated, with some probability, that the excessive proportion of fat renders the cocoa difficult of digestion. Hence the removal of a portion of the fat, and consequent concentration of the non-fatty constituents of the cocoa, appears to be distinctly advantageous. A further treatment of the concentrated cocoa is practised by some manufacturers of cocoa-essence, especially by Dutch firms. This treatment consists in the addition to the cocoa of an alkali, which may be either ammonia or a fixed alkali or alkaline car- bonate, whereby the fat becomes emulsified and any free fatty acids saponified. Hence, on subsequently treating the cocoa with hot water there is less tendency to the separation of oily globules. The effect on the composition of the cocoa is shown in the results of Stutzer on page 560, from which it appears that the fact of the treatment can be readily detected. In the case of a well-known brand of cocoa, potassium carbonate is used. In another case, the cocoa- beans are soaked in water containing from 2 to 4 per cent, of their weight of caustic potash or soda. The following figures were obtained by the analysis, in the author's laboratory, of a specimen of the best cocoa-nibs and two of the leading brands of cocoa-essence or soluble cocoa, to which no starch or sugar had been added : — Cocoa- Sample Sample nibs. A. B. Per cent. Per cent. Per cent. ash:- 2-53 4-93 8-25 Insoluble in water, 1-71 3*50 2-09 Soluble in water, 0-82 1-43 6-16 Alkalinity (KgO) of soluble portion, . . . . Cold Water Extract :— 0-32 9-72 0-49 11-64 3-23 18-66 Alkalinity (K2O) to methyl-orange, . . . . Acidity (K2O) to phenolphthalein, . . . . 0-69 0-71 202 0-63 0-76 0-38 Hot Water Extract :— 16-84 20-36 27-16 Containing :— Ash, 3-34 4-93 7-85 Organic extract, 13-50 15-43 19-31 ^"Chocolate creams" consist of a core or kernel of pure sugar, enveloped in a mixture of ground cocoa, cacao-butter, sugar, and flavouring materials. COMMERCIAL COCOAS. 563 The curious property possessed by the cold-water extract of being at once alkaline to methyl-orange and acid to phenolphthalem indicates the presence of a soluble salt of some weak organic acid, together with a small proportion of free organic acid. The treat- ment with alkali which sample B had received appears to have notably increased the proportion of matter actually soluble in water. The misuse of the term "soluble" by cocoa manufacturers is notorious; the real object sought, and to some extent attained, being the formation of an emulsion which is readily miscible with hot water. This desideratum is the more important owing to the difficult digestibility of some of the nitrogenous constituents of cocoa (see page 559). The following results, among many others, were obtained by E. E. E well {Bulletin No. 13, U.S. Department of Agriculture) by the analysis of well-known brands of commercial cocoa and its pre- parations : — Description of Sample. ^ S i 1 CO s 1 h S be 1- Ash. Added Starch. Total. Acid- equiva- lent.2 Fry's Cocoa Extract . 1 30-95 3-89 ... ... 4-21 5-8 None. Schweitzer's Cocoatina, 1 31-13 3-70 ... ... 6-33 9-4 None. Van Houten's Cocoa, . 1 29-Sl 4-33 ... ... 8-64 1605 None. Blooker's Dutch Cocoa, 31-48 3-76 ... 6-06 9-6 None. Rowntree's Extract \ of Cocoa, . . / 2 27-56 4-42 ... 8-48 16-6 None. Rowntree's Powdered I Chocolate, . . / 2 25-84 1-30 61 none 1-66 2-25 ( Very small amount ( of arrowroot. Epps' Prepared Cocoa, ... 25-94 1-61 26 none 8-15 2-6 Much arrowroot. Fry's Diamond Sweet \ Chocolate, . . / 2 18-60 -81 55 some 1-16 1-45 (Much wheat-starch ■I with some arrow- ( root. London Cocoa (un-\ known maker), . / 3 11-13 2-13 32 some 2-82 8-9 /Very largely diluted \ with arrowroot. Chocolat-Menier, 21-31 1-10 58 none 1-40 2-05 None. 1 In the column headed " husk," signifies that no characteristic husk-tissue could be found under the microscope; 1 signifies that the husk had probably been mostly removed ; 2 signifies that the husk had probably been partly removed ; and 3 that the husk was prob- ably all present. But Ewell's observations with respect to the husk of commercial cocoas are not in all cases borne out by the examination of other samples of the same prepara- tions, and must be received with caution. 2 The figures in the column headed "acid-equivalent" represent the number of c.c. of decinormal acid required to neutralise the ash from 2 grammes of the sample. It is a rough measure of the fixed alkali used in the manufacture. 564 COMMERCIAL COCOAS. Owing to a considerable proportion of the natural fat having frequently been removed, the proportion of real cocoa in a mixture cannot be assumed to be approximately double the percentage of fat. A better idea of the proportion of the additions is obtained by stating the fat and non-fatty constituents separately. This plan is adopted by J. Bell, and is shown in the following analyses by him, representing the composition of certain commercial pre- parations of cocoa : — Description. Moisture. Fat. Added Sugar. Added Starch. Non-fatty Cocoa G)y differ- ence). Nitrogen. Finest Trinidad nibs, . 2-60 51-77 none none 45-63 2-95 Cocoa Extract, . 5-76 29-50 none none 64-74 Not determined. Flake Cocoa, . 5-49 28-24 none none 66-27 3-06 Gocoatina, 3-62 23-98 none none 72-50 4-07 Chocolatine, . 4-40 29-60 none none 66-00 4-36 Chocolat de Sant^, 1-44 22-08 61-21 2-00 13-27 Not determined. Prepared Cocoa, . 4-95 24-94 23 03 1919 27-89 2-24 Iceland Moss Cocoa, . 5-47 16-86 29-23 24-70 23-74 1-38 Rock Cocoa, . 2-58 22-76 32-20 17-56 24-90 Not determined. According to evidence given in the case of G i b s o n v. L e a p e r, " Epps' cocoa " contains 40 per cent, of cocoa, 1 6 of starch (West Indian arrowroot), and 44 per cent, of sugar. " Granulated cocoa " is chiefly a mixture of cocoa-nibs, sugar, and arrowroot ; while in "Maravilla cocoa" the arrowroot is replaced by sago. Bernhardt states that he has met with chocolates consisting of cocoa-remnants, fat, sugar, spices and colouring matter, and containing no true cocoa whatever. The cocoa-butter is said to be liable to be replaced by cheaper fats, and vanilla and vanillin by Peruvian or Tolu balsam, storax, or gum benzoin. Analysis of Commercial Cocoa and Chocolate. The complete analysis of cocoa is rarely required. A careful microscopic examination will indicate the presence, and in many cases the nature, of most foreign additions, and prove the presence of husk -structure. The various starches may also be identified by the microscope. The proportion of fat affords further informa- tion, and the percentages of sugar and starch complete what is usually required, unless it is desired to ascertain the nature and amount of the alkali added. The following scheme of analysis will allow of the above information being obtained : — ANALYSIS OF COCOA MIXTURES. 565 Ignite 5 grammes of the sample, weigh the ash and treat with hoihng water. Wash, dry, ignite, and weigh the insoluble portion. Titrate the filtrate with decinormal acid to determine the alJialinity, which will be excessive where the cocoa has been prepared with a fixed alkali. The addition to cocoa of ferruginous pigments, such as rouge, ochre, and venetian-red, was formerly practised, and the author was recently consulted as to the probable legal consequences of their use. He has also examined a pre- paration consisting essentially of oxide of iron, which has recently been offered to cocoa-manufacturers. Where the proportion of the diluents is large, the importance of deepening the colour of the mixture is considerable. The addition of ferruginous matters would be readily detected by the excessive proportion of the ash, which in the case of genuine cocoa is white, and very rarely in excess of 4 per cent, (in the absence of husk and added alkalies, and when the fat has not been removed). The proportion of oxide of iron in cocoa is very trifling, ranging from 0*10 to 0'38 per cent, of the ash, while even in the husk it only amounts to 0"63 per cent. of the ash. Dry 5 grammes of the sample in the water-oven at 100° C. and note the loss of weight, which represents moisture. Boil the dried substance, reduced to powder if necessary and preferably mixed with a known weight of dry sand, with redistilled petroleum spirit. Pour off the solution, and repeat the treatment till the fat is entirely removed. Wash the residue, dry it in the bath and re weigh. The loss represents fat, with a near approach to accuracy. A direct determination may be obtained by evaporating the petroleum spirit, and the physical and chemical characters of the residual fat can then be ascertained.^ The residue left after the extraction of the fat is exhausted with hot spirit of 0"850 specific gravity, which dissolves sugar, tartaric acid, tannin, soap, theobromine, &c. Ihe hot solution is treated with lead acetate and filtered from the precipitate of lead tartrate^ tannate, stearate, &c. From the concentrated filtrate the theo- hromine can be extracted by agitation with warm chloroform, but where the determination is not required this stage of the process may be omitted. The aqueous liquid is freed from traces of chloro- form by boiling or agitation with petroleum spirit, and after removal ^ Cocoa which has been treated with an alkali contains a notable quantity of soap, which is not dissolved by the petroleum ether. It is best extracted by treating the residue with alcohol containing a few drops of hydrochloric acid, evaporating the alcoholic solution, and shaking the residual liquid with water and ether. On separating and evaporating the ethereal layer, the fatty acids of the soap will be left. 566 SUGAR IN COCOA. of the excess of lead by sodium phosphate is fit for determination of the sugar. This may be effected by inversion and treatment with Fehling's solution, or by means of the polari meter. The difference in the amount of sugar found before and after inversion represents the cane-sugar added. The alcoholic extract of genuine cocoa, after treatment with lead acetate,, does not sensibly reduce Fehling's solution, so that any precipitate yielded before inversion represents glucose^ introduced as such or present in the cane-sugar added.^ The residue left after treatment with alcohol contains gum, starch, cellulose, fibre, albuminoid matters, &c. After weighing, an aliquot part may, if desired, be used for the determination of the contained nitrogen by Kjeldahl's process or combustion with soda-lime, and the amount found calculated to albuminoids by multiplying by 6-25. The residue may also be advantageously examined under the microscope at this stage, since by the removal of the oil, sugar, and colouring matters the starch and woody structure are seen to great advantage. On the presence or absence of foreign starch will usually depend the necessity of performing the subsequent operations for its quantitative determination. For the determination of starchy an aliquot part of the residue from the alcohol treatment 2 should be heated, under a pressure of ^ A determination of the amount of sugar added to cocoa can be readily effected to within 2 per cent, of the truth, but a strictly accurate estimation is not required, and would be very difficult. The sugar can be determined in the aqueous instead of the alcoholic extract of the cocoa, but in that case the solution contains the natural gum, which has a dextro-rotatory power equiva- lent to 0*3 to 2*0 per cent, of cane-sugar in the somple, and a large volume of cold water must be used for the extraction. E. E. E w e 1 1 {Bulletin No. 13, U.S. Department of Agriculture) recommends the following method for the polarimetric determination of sugar in the aqueous extract of cocoa :— 13'024 grammes weight of the material is triturated in a small mortar with alcohol until a smooth paste is obtained. This is transferred to a 500 c.c. flask, diluted with about 400 c.c. of water, and the liquid shaken occasionally for three or four hours, when 10 c.c. of a saturated solution of neutral lead acetate should be added and the volume brought to 500 c.c. After standing for an hour with occasional agitation, the solution is filtered and polarised in a 4 decimetre tube (twice the usual length). If the instrument be one intended for use with 26*048 grammes of sugar, the percentage of cane-sngar in the sample will be found by the following formula, in which R is the reading in sugar-units : — ^ frnn no.no^x RRxl3-024-l ^ „ Tqq 500-(13"024) — — =percent. of sucrose. ' The residue is preferably first treated with cold water, to dissolve gummy matters, but except in cases where great accuracy is required this part of the process may be omitted. STARCH IN COCOA. 567 1 atmosphere, for one hour with 50 c.c. of water and 1 c.c. of fuming hydrochloric acid.^ This treatment effects the complete conversion of the starch into maltose and dextrin, and the further change of these to dextrose, without appreciahly affecting the cellulose. The solution is filtered from the insoluble matter, fibre (sand), &c., and the dextrose determined in the neutralised filtrate by Fehling's solution. Ten parts of dextrose found represent 9 of starch in the sample. The mixed cellulose, fibres and sand, left after the conversion of the starch by hydrochloric acid, should be treated with a solution of 2 per cent, caustic soda to remove nitrogenous matters, washed successively with very dilute hydrochloric acid, alcohol and ether, dried and weighed.^ An alternative method of estimating starch consists in treating the fat-free cocoa with cold water, to remove all sugar, gum, &c. The liquid is filtered and the residue washed with decinornml caustic soda (4 grammes ISTaHO per litre) to remove albuminoids. The residue is rinsed off the filter with warm water, the liquid heated to boiling while constantly stirred, so as to gelatinise the starch, and the product treated with a known measure of recently- prepared and filtered cold aqueous infusion of malt, of which the specific gravity has been previously ascertained. The mixture is kept at a temperature of 60° to 63°, with occasional stirring, until a drop taken out with a glass rod and added to a drop of dilute iodine solution on a porcelain plate shows no blue or brown colora- tion. The solution is then filtered, made up to a definite volume, ^ A simple and convenient apparatus for effecting the conversion consists of a soda-water bottle fitted with an india-rubber stopper, through which passes a long glass tube bent twice at right angles and immersed to a depth of 30 inches in mercury contained in a long vertical glass tube or piece of narrow (iron) gas-pipe. The stopper should be carefully secured by wire. The soda- water bottle may be heated in a bath of paraffin or oil, or in a boiling saturated aqueous solution of sodium nitrate. This last liquid has a tem- perature of 121° C, corresponding to one additional atmosphere of pressure, so that no regulation is required, and if preferred the exit-tube may be dis- pensed with and the cork or stopper firmly secured in position. * For the direct determination of the crude fibre, 2 grammes of the sample of cocoa should be freed from fat and boiled for half an hour under a reflux condenser with 200 c.c. of water and 1\ c.c. of sulphuric acid. The liquid is filtered through linen and the residue thoroughly washed with hot water and then boiled with 200 c.c. of 1 J per cent, caustic soda. The residue is filtered off, washed in succession with hot water, alcohol, and ether, dried at 110°, and weighed. It is then ignited, and the loss regarded as crude fibre. In cocoa free from husk it will amount to 2 or 3 per cent, only, but will exceed this limit in proportion to the amount of husk present. 668 ANALYSIS OF COCOA. and its specific gravity accurately ascertained. From the excess of the density over water is subtracted the density due to the infusion of malt used, allowance being made for the increased volume of the liquid, when the difference represents the density due to the starch dissolved, and this number divided by 4*096 ( = 3'95, the density-coefficient of a solution of mixed maltose and dextrin, multiplied by 1*037, the yield of these from 1 part of starch) gives the number of grammes of starch in each 100 c.c. of the solution.^ The total nitrogen of cocoa can be determined on 2 to 3 grammes by Kjeldahl's method, or by combustion with soda-lime. The assumption that the proportion of albuminoids can be found by multiplying the nitrogen by 6*25 leads to an estimate greatly in excess of the truth. The theobromine of cocoa contains 31*1 per cent, of nitrogen, or nearly twice as much as albumin. Hence to obtain an estimate of proteids from the nitrogen of the sample, the proportion of that element corresponding to the theobromine present must first be deducted. But as the determination of theobromine is somewhat troublesome, it is preferable to operate on a cocoa-residue which has been already exhausted with petroleum spirit, alcohol, and amylic alcohol or chloroform, so as to eliminate with certainty the whole of the theobromine. Cacao-butter {Oleum Theohromatis) is the fat contained in cocoa- beans, and must not be confused with cocoa-nut oil from Cocos nucifera. Cacao-butter is expressed from cocoa in the process of manu- facture, and by far the larger quantity used in the United Kingdom is the produce of one firm. It is used in pharmacy ; for the pro- duction of some kinds of chocolate ; and in the manufacture of high-class soap. Cacao-butter is liable to adulteration with or substitution by other fats, and it is said that the cacao-butter is sometimes very completely expressed from cocoa and replaced by tallow, cocoa-nut oil, or other comparatively cheap fat. A careful observation of the physical and chemical characters of ^ Thus, suppose 20 grammes of the sample of cocoa be taken, and, after extraction of the fat and treatment with cold water and soda in the manner described, the residue be treated with 50 c.c. of water and 5 c.c. of infusion of malt of 1060 specific gravity ; the liquid being subsequently made up to 100 c.c. and found to have a density of 1023. Then the correction due to the malt-extract will be "lO O^^ "°^ ' ^"^ *^^^ ^^ure, subtracted from the density of the solution less that of water (1023-1000 = 23), leaves 20 as the excess-density caused by the solution of the starch of the sample ; and this figure divided by 4*096 gives 4-9 grammes per 100 c.c. or in the 20 grammes taken ; or 24-5 per cent, of starch in the sample. CACAO-BUTTER. 569 cacao-butter will allow of the detection of other fats, if present in any considerable proportion. Pure cacao-butter is a yellowish fat, gradually becoming paler on keeping.^ At the ordinary temperature it may be broken into frag- ments, but softens in the hand and melts in the mouth. Cacao- butter has an agreeable odour, tastes like chocolate, and does not readily become rancid. It dissolves in 20 parts of hot alcohol, separating almost completely on cooling, and is also soluble in ether, acetic ether, &c. Cacao-butter owes its value for the production of pessaries and suppositories to the fact of its having a melting-point slightly below the temperature of the human body (98° F. = 36'6° C). According to most observers, it fuses between 30° and 33° C. (rarely at 26°) to a transparent yellowish liquid, which congeals again at 20°— 21°, the temperature rising to about 27° C. According to the British Pharmacopoeia, the melting-point of cacao-butter ranges between 30° and 35° C. (86°-95° F.).^ ^ It is to be regretted that the yellowish tint of cacao-butter is not more generally recognised as a natural characteristic. It is probable that the quality of cacao-butter is necessarily affected for the worse by any process of decolorisation. 2 R. Benseraaun {Zeit. Anal. Chem., xxiv. 628 ; Joicr. Soc. Chem. Ind., iv. 535) has observed the melting-point of cacao-butter and the fatty acids resulting from its saponification, and finds the figures for the latter remark- ably constant. He places a drop of the previously-melted fat or fatty acid in the wider part of a piece of quill-tubing drawn out to a capillary form and closed at one end. The substance is allowed to solidify completely, and the tube is then attached to a thermometer and placed in water, which is gradually heated. The temperature at which the substance becomes sufficiently fluid ta run down into the capillary part of the tube is called the point of incipient fusion. When the substance has melted and run down into the shoulder of the tube, and shows no trace of turbidity, the temperature recorded is the concluding point of fusion. Bensemann records the following results : — Source of Cacao-butter. Fat. Fatty Acids. Initial Melting-point. Initial Melting-point. Concluding Melting-point. Percentage of Insoluble. Maracaibo beans, . 25-26° C. 48-49° C. 51-52° C. 94-59 Caraccas beans, 27-28 48-49 51-52 95-31 Trinidad beans. 26-27 49-50 52-53 95-65 Portoplata beans, . 28-29 49-50 52-53 95-46 Machala Guayaquil \ beans, . . . / 28-29 49-50 52-53 95-24 570 MELTING-POINT OF CACAO-BUTTER. T. M. C 1 a g u e has recently pointed out (Pharm. Jour., [3], xxiii. 247) that the melting-point of commercial cacao-butter extends over a considerably greater range than the above, and is materially affected by the temperature to which it has been exposed. Thus, the melting-point of ten trade samples ranged from 73°-91° F. A sample expressed by heat direct from cocoa-nibs melted at 91°, while the fat obtained from the same nibs by extraction with ether melted at 83° F. Similarly, the fat extracted by ether from a "cocoa-essence" had a melting-point of 96°, while the cacao- butter extracted by heat and pressure by the same firm melted at 75° F., thus showing that a certain amount of fractionation occurs in the ordinary process of extraction by pressure. T. M. C 1 a g u e further observed the following suggestive alterations of melting-point when cacao-butter was heated to various temperatures. Nos. 1 and 2 were ordinary trade samples, and hence had been already heated in the process of manufacture. No. 3 was extracted by ether from unroasted cocoa-nibs, and hence excessive heating had been entirely avoided : — Melting-point ; ... No.l. No. 2. No. 3. Original, ... 75 86 86 After being heated to 105° F., 75-5 89 86 » 120', 84 85 91 ., ir,o\ ....... 85 83 92 180% 80 80 85 The melting-point of No. 1 sample was raised to 86° F. by keeping it at a temperature just under 100° F. for two hours. The determinations of melting-points were made on metallic mercury, substantially by method c described in Vol. II. page 23.1 Cacao-butter contains the glycerides of stearic, oleic, and a little lauric, palmitic, and arachidic acids. C. T. Kingzett obtained from cacao-butter an acid of the formula Cg4Hi28^2J ^^icli ^e named theobromic acid. P. Graf isolated 9*59 per cent, of glycerol, and detected a little cholesterin and small quanti- ties of formic, acetic, and butyric acids. * T. M. Clague has also described experiments showing that deternnnations of the melting-point of cacao-butter by the capillary tube method are very gravely afifected by the diameter of the tube employed. EXAMINATION OF CACAO-BUTTER. 571 The iodine-absorption of a large number of samples of cacao-butter from different sources has been determined by F. Filsinger (Ghem. Zeit, xiv. 7 1 6), and found to range from 3 3 "4 to 37*5. The saponification-equivalent ranges a few degrees on each side of 280, which figure corresponds to 20'03 per cent, of potash (KHO) required for saponification. Filsinger found the potash required to range from 19 "2 to 20*2, and Weigmann from 19*84 to 20'30. An admixture of paraffin wax would reduce the percentage of alkali required for saponification. The specific gravity of solid cacao-butter is variously stated. The author found the plummet-gravity at 98° C. to be 0"8577. Any admixture of paraffin wax would reduce this figure, while cocoa-nut oil would increase it. Foreign fats in cacao-butter tend to alter the foregoing characters, but observations of the melting-point and specific gravity do not usually furnish satisfactory means of detecting such admixtures. Tallow is said to be capable of detection by saturating a cotton thread with the oil, allowing it to burn for a short time, and then blowing it out, when the odour of tallow becomes perceptible. A better test for tallow and other adulterants of cacao-butter is to dissolve 2 grammes of the fat in 4 grammes ( = 5'5 c.c.) of ether at 17°-18° C.,^ and then immerse the closely-corked test- tube in ice-cold water. Granules will separate from, or turbidity be produced with, pure cacao-butter, in not less than 3 and more frequently in from 5 to 8 minutes, sometimes delayed to 10 or 15 minutes ; while if fallow or suet be present, a turbidity will appear at once, or within 2^ minutes, according to the proportion of the adulterant, of which 5 per cent, may thus be detected. On expos- ing the solution to a temperature of 14° to 15°, it will gradually become clear again, or more rapidly at 20°, if the cacao-butter was pure, but not if it was adulterated. With a sample containing 5 per cent, of tallow, turbidity occurs in 8 minutes, and the solution does not become clear below 22°; while with 10 per cent, of tallow, the turbidity occurs in 7 minutes, and the clearing- point is 25° C. This test is due to Bjorkland (Zett. Anal. Chem.y iii. 233), and is adopted in the United States Pharmacopoeia. Its value has been confirmed by other observers, of whom Lamhofer has pointed out that petroleum-ether may be employed with similar results, except that the cacao-butter separates rather more slowly than from ether, the deposit being always granular, while other fats render the entire liquid cloudy. The solution of cacao-butter in two parts of ether will remain clear for an entire day if maintained ^ A failure to obtain a clear solution points to the presence of paraflSn wax. 672 EXAMINATION OF CACAO-BUTTER. at a temperature of 12° to 15° C. This modification of the test is prescribed by the German Pharmacopoeia, and is due to R a m- sperger, who states that aniline may be substituted for the ether. Fil singer (Zeit. Anal. Chem., xix. 247) has described the following modification of the ether-test : — Two grammes of the fat should be melted in a graduated tube with 6 c.c. of a mixture of 4 volumes of ether (sp. gr. 0*725) and 2 volumes of alcohol (sp. gr. 0'810), shaken, and set aside. Pure cacao-butter gives a solution which remains clear. According to E. Dietrich, a very reliable test for the purity of cacao-butter consists in warming the sample with an equal weight of paraffin oil. A drop of the mixture is placed on a slip of glass, a thin cover applied, and the slide exposed for twelve hours to a temperature not exceeding 5° C. When then examined with polarised light, under a magnifying point of 20 diameters, the crystals of cacao-butter present the appearance of palm-leaves, showing a fine play of colours with selenite. An addition of 10 per cent, of beef-tallow causes the fat to crystallise in tufts of needles, or circular groups of crystals, which exhibit a black cross ; while if mutton-tallow be the adulterant, it is stated that no cross can be seen. 7. 8. 9. 10. 11. 12. 13. References to Photographs of Leaves. {See page 522.) Plate I. Plate II. Camellia Thea. Tea. Marattia Elegans. EpilohiumAngiistifolium. French Willow or Willow Herb. Salix Alba. Willow. Tlex Paraguayeiisis. Paraguay Tea or Brazilian Holly. Popultcs Nigra. Poplar. Sam^itcus Nigra. Elder. Ulmtis Campestris, Elm. Betula Alba. Biich. Prurms Spinosa. Sloe or Black- thorn. Prunus Cerastes. Cherry. Rubus IdcBus. Raspberry. Camellia Sasanqua. 14. Camellia Thea. Tea. 15. Ribes Grossularia. Gooseberr}'. 16. Rosa Canina. Dog Rose. 17. Coffea Arabica. Coffee. 18. Cratcegus Oxyacantha. HaAv thorn. 19. Fragaria Vesca. Strawberry. 20. Pyrus Malus. Apple. 21. Quercus Robur. Oak. 22. Ribes Nigrum. Black Currant 23. Fraximis Excelsior. Ash. 24. Fagus Sylvatica. Beech. 25. Rubus Fructicosus. Black- berry. 26. Prunus Communis. Plum. PUte I, A.S.Huth.Lith' U Plate II 25. A.S.Huth.Lith'". London INDEX. AOETAMIDE, 2 Acetanilide, 63, 67, 68 detection of, 69, 83, 84 Aceto-amidophenol, 68 Aceto-anisidine, 68, 85 Acetophenone, 68 Acet-phenethidine, 68, 81 Acet-phenylhydrazine, 28, 68 Acid, aconitic, 207 amalic, 480 amidobenzene-sulphonic, 49 amidonaplithol-sulphonic, 94 aniline-sulplioiiic, 49 atropic, 245 berberonic, 112, 4G3 boheic, 501 caffeic, 529 caflfeidine-carboxylic, 479 caflfelannic, 529 chelidonic, 166 chlorogenic, 529 chrysatropic, 262 cinchomeronic, 112, 165 cinchofulvic, 445 cinchotannic, 444 cocaic, 286 cocatannic, 291 columbic, 472 comenic, 337 cotarnic, 299 diniethyl-parabanic, 4S1 dipicolinic, 112 hemipinic, 298, 463 hydrochloric, as a reagent, 145 hydroquinine-sulphonic, 425 hydrastinic, 470 igasuric, 384 Acid, isatropic, 246, 286 isococaic, 287 isonicotinic, 111 kinic, 445 leucotropic, 263 lutidinic, 112 lycoctonic, 225 meconic, 336 „ detection of, 338, 358 metatungstic, as a reagent, 137 methylparabanic, 494 nicotinic, 111 nitric, as a reagent, 146 opianic, 203, 298 phosphoantimonic, as a reagent 137 phosphomolybdic, 136 phosphotungstic, 136 picolinic. 111 picric, as a reagent, 134 pyridine-carboxylio, 110, 112 pyromeconic, 337 quinic, 445 quinolinic, 112 quinovic, 444 silicotungstic, as a reagent, 137 strychnic, 384 strychnine-monosulphonic, 363 sulphanilic, 49 sulphomolybdic, as a reagent, 147 sulphoselenic, as a reagent, 145 sulphovanadic, as a reagent, 148 sulphuric, as a reagent, 145 tannic, as a reagent, 135 tannic, in tea, 491, 515 tropic, 245 trimethyl-thiocarbamic, IG 574 INDEX. Acid, uric, colour-reaction of, 473 Acolyctine, 224 Aconine, 202, 204, 214, 232, 235 Aconite, assay of, 228 official preparations of, 199 poisoning by, 236 toxicological detection of, 24 J various species of, 199, 201 Aconitine, 207 amorphous, 201, 215, 218 anliydro-, 205, 213 characters of, 202, 209 composition of, 205 constitution of, 203, 205 detection of, 211, 240 determination of, 231 , 233 poisoning by, 209, 236 saponification of, 133, 203, 213, 233 titration of, 231 Acridine, 123 Alkaloids, aconite, 198, 201, 202 behaviour of, with immiscible sol- vents, 154, 158, 159 of belladonna, 263 of berberis, 461, 465 of celandine, 295 of chelidonium, 295 of cinchona, 391 of coca, 270 colour-reactions of, 144 of dita bark, 437 effect of, on the pupil, 150 of eschscholtzia, 296 extraction of, by immiscible sol- vents, 154, 158, 159 extraction of, from plant-products, 151, 160 general precipitants of, 134, 153 of hemlock, 171 of henbane, 250, 267 of hydrastis, 461, 467 isolation of, 151 of lupine, 178 mydriatic, 244 of nux vomica, 384 of opium, 293 Alkaloids, of Remijia barks, 384 oxidation colour-reactions for, 149, 314, 368, 469, 480 physiological tests for, 149 purification of, 162 1 eactions of, with Czumpelitz's reagent, 144 Dragendorff s reagent, 138 Erdmann's reagent, 148 ferric chloride, 148, 304, 313 Frohde's reagent, 147 Hager's reagent, 134 hydrochloric acid, 145 Kundrat's reagent, 148 Mayer's reagent, 138, 153 Marme's reagent, 138 nitric acid, 146 Scheibler's reagent, 136 Sonnenschein's reagent, 136 — ^ sulphuric acid, 145 "Wagner's reagent, 137 Wormley's reagent, 137 zinc chloride, 144 strychnos, 362 Alpha-naphthylamine, 90, 91 Alloxantin, 480 Alstonine, 437 Amido-benzene, 43 sulphonic acids, 49 naphthols, 94 -naphthol -sulphonic acids, 95 paraphenacetin, 85 -pentamethylbenzene, 60 phenols, 80 thiophene, 63 Amines, classification of, 1 distinction of, 7 ferrocyanides of, 8 reaction of, with nitrous acid, 7 with aldehydes, separation of, 4 Amiuol, 15 Ammonium bases, 18 Analgesin, 32 Anhydro-aconitine, 205, 213 -bases of aconite, 205 -ecgonine, 251 INDEX. 675 Anliydro-tropines, 251 Antifebrin, 68 Antithenniu, 31, 68 Antipydne, 32 chloral-, 38 nitroso-, 34 Antiseptin, 68, 71 Apo-aconitine, 213 Apo-atropine, 251 Apo-bases, see Anbydro-bases Apocodeine, 324 Apornorpbine, 319 Arginine, 167, 178 Aricine, 393, 436 Atisine, 226 Atropamine, 244, 251 Atropine, and its allies, 243 anhydro-, 251 constitution of, 165, 244 products of saponification of, 244 reactions of, 254 toxicological detection of, 261 Azobenzene, 63 Azo dyes, 42 Azoimide, 24 Bases from tea, 39 Belladonna, alkaloids of, 263 assay of, 264 composition of, 262 extract of, 269 Belladonnine, 244, 252 Benzanilide, 72 Benzidine, 88 Benzoyl-aconine, 207 -anbydro-aconitine, 206 -ecgonine, 270, 282 -japaconitine, 221 methylecgonine, see Cocaine pseudotropine, 244, 287 -tropine, 253 Beuzylamine, 51 Berbamine, 461, 466 Berberine, 461 salts of, 464 Berberis alkaloids, 461 Beta-naphthylamine, 90, 92 Bromacetanilide, 68, 71 Bruciue, 381 constitution of, 168, 381 dinitro-, 382 reactions of, 382 separation of, from strychnine, 366 Butylamine, 14 Caffeidine, 479 carboxylic acid, 479 Caffeine, 474 assay of tea for, 490 constitution of, 167, 473 determination of, 484 natural occurrence of, 474 presence of, in cocoa, 495 proportion of, in tea, 492 in coffee, 528, 552 reactions of, 480 salts of, 482 solubilities of, 477 Calumba root, 471 Camphor, compound tincture of, 853 Canadine, 470 Carbazol, 113 Cevadine, constitution of, 133, 166 Cevine, 133, 166 Chairamidine, 393, 436 Chairamine, 393, 436 Chelidonine, 295 Chelerythrine, 295 Chicory, composition of, 538, 544 detection of, in coffee, 540 determination of, 542, 545, 550 Chinoliue, see Quinoline Chinovin, 443 Chloral-antipyrine, 38 Cholestrophane, 481 Chocolate, 561 Choline, 18, 133, 167 Cinchamidine, 433 Cincholeupone, 168 Cinchona alkaloids, 391 amorphous, 433 general properties of, 394 proportion of, in bark, 445 576 INDEX. Cinchona alkaloids, separation of, 453 list of, 392 barks, 440 assay of, 449 composition of, 442 proportion of alkaloids in, 445 Cinchonaniine, 392, 436, 438 Cinchona-red, 445 Cinchonicine, 435 Cinchonidine, 392, 397, 428 constitution of, 168 determination of, 410, 413, 430, 449, 459, 460 homo-, 430 hydro-, 432 Cinchonine, 392, 397, 431 constitution of, 168 decomposition-products of, 168 determination of, 413, 459, 460 hydro-, 392, 432 Cinch otannin, 444 Cinchotenine. 168 Cinchotine, 392, 432 Cinnamyl-cocaine, 271, 285 ecgonine, 270, 272 Coca, alkaloids of, 270 amorphous bases of, 287 leaves, 290 extraction of alkaloids from, 292 Cocaine, 273 amorphous, 287 cinnamyl-, 285 commercial, 278 constitution of, 166, 271 decomposition-products of, 282 dextro-, 284 homo-, 285 hydrochloride, 277 saponitication of, 272, 282 Cocamine, 271, 272, 286 Cocethyliue, 285 Cocoa, adulterations of, 561 analysis of, 564 commercial, 561 butter, 558, 568 Cocoa, composition of, 556 essence of, 661 husks, 556, 557, 561 nitrogenous constituents of, 559 Codamine, 294, 301, 304. 320 Codeine, 294, 321 Cotfee, 527 adulterations of ground, 538 beans, 533 caramel in, 539 composition of, 528 detection of chicory in, 540 detection of starch in, 541 factitious, 535 imitation, 535 -parchment, 528 physiological action of, 632 roasting of, 530 Colchicine, 166 Collidines, 97, 109 Columbin, 472 Conchairamine, 398, 436 Concusconine, 393 Conhydrine, 171, 173 Coniceines, 174 Conine, 171 assay of hemlock for, 176 determination of, 176 poisoning by, 175 Conium, 176 alkaloids of, 171 tincture of, 177 Conquinamine, 372, 427 Conquinine, see Quinidine Cotarnine, 299 Cryptopine, 294, 301, 304, 324 Cumidines, 59, 63 Cupreine, 392, 397, 438 constitution of, 169, 398, 439 separation of, 413, 438 Curare, 387 Curarine, 371, 389 Curine, 390 Cuscamidine, 393 Cuscamine, 393 Cuscouidiue, 393 Cusconine, 393 INDEX. 577 Deutekopine, 295, 324 Diamide, 22 Diamidogen, 22 Diaraido-benzenes, 86 Diamido-phenols, 83, 85 Diantipyrine, 31 Diazo-compounds, formation of, 7 Dicinchonicine, 393, 435 Diethylaniline, 73, 79 Diethylene-diamine, 2, 106 Dietliyl-hydrazine, 26, 27 oxamide, 5 Dimethylamine, 12 reactions of, 10 Dimethylaniline, 73, 74 commercial, 76 Exalgin, 68, 71 Extract of aconite, 229 belladonna, 266, 269 cinchona, 445 cocoa, 561 coffee, 553 hemlock, 77 henbane, 269 nux vomica, 386 opium, 350 tea, 505 Flavaniline, 69 Forrayl-paraphenethidine, 85, 373 Furfuran, 113 Dimethylnitrosamine, 7 Gelsemine, colour-reactions of, 145, Dinaphthylene-diamines, 93 146, 149, 437, 469 Dinitrobenzenes, 63 Glaucine, 296 DipLenylainine, 79 Glaucopicrine, 296 Diphenylaniline, 79 Glucosides, behaviour with immiscible Diphenylene-diainines, 86 solvents, 158, 159 Diquinicine, 393, 435 colour-reactions of, 146, 147, 148 Dita bark, 436 Gnoscopine, 294, 301, 324 Ditaine, 436 Ditamine, 436 Hemlock, assay of, 176 Ditoluylene-diamine, 87 lesser-, 175 Dinretin, 497 poisoning by, 175 tincture of, 177 Easton's syrup, 376 water-, 175 Echitamine, 436 Henbane, alkaloids of, 250, 267 Echitenine, 436 assay of, 267 Ecgonine, 283 extract of, 269 anhydro-, 284 Herepathite, 138, 402, 454 benzoyl-, 282 Homatropine, 253, 254 constitution of, 166, 270, 284 Horaoquinine, 439 Ethyl di ethyl oxamate, 5 Hydracetin, 28, 68 oxalate, 5 Hydrastine, 461, 467 Ethylamine, 14 colour-reactions of, 469 reactions of, 10, 17 Hydrastinine, 470 Ethylamines, 17 Hydrazine, 22 Ethylaniline, 73 ethyl-, 26 Ethyl-hydrazine, 26 hydrate, 22 morphium compounds, 18 phenyl-, 27 strychnium compounds, 19 salts, 23 thalline, 121 Hydrazines, 22 Euphorin, 68, 72 substituted, 25 VOL. III. part II. 2 578 INDEX. Hydrazobenzene, 89 Hydrazones, 30 Hydrazonium compounds, 25 Hydroacridine, 126 Hydrocinchonidine, 392, 410, 430 Hydrocinchonine, 392, 432 Hydrocotarnine, 294, 301, 304, 309, 325 Hydrohydrastinine, 470 Hydroquinicine, 425 Hydroquinine, 424, 410, 415 Hyoscine, 244, 250 reactions of, 254 saponification of, 244 Hyoscyamine, 244, 249 reactions of, 254 saponification of, 244 Hyoscyamus, see Henbane Hypnone, 68 Hygrine, 289 Imidazoic acid, 24 — Immiscible solvents, behaviour of alka- loids with, 159 behaviour of organic sub- stances with, 158 extraction by, 154 Inflatin, 196 lodol, 114 Iridoline, 115 Isoduridine, 60 Isotropine, 270 Japaconitine, 202, 204, 220 benzoyl-, 221 saponification of, 204, 221, 233 Javanine, 392 Kairine, 120 Kairoline, 119 Kakotelin, 383 Kola, 554 Kynurine, 168 Lanthopine, 294, 301, 304, 308, 325 Laudanine, 294, 301, 304, 308, 325 Laudanosine, 294, 301, 304, 309, 325 Laudanum, 350 Lobelia, alkaloids of, 195 Lobeline, 195 Logan etin, 385 Loganin, 385 Lupanine, 179 Lupine alkaloids, 178 Lupinidine, 179 Lupinine, ]67, 178 Lutidine, 97, 108 Lyaconine, 224 Lyaconitine, 202, 222 Lycoctonine, 224 Mate, 526 Meconates, 339 Meconarceine, 327 Meconic acid, 336 detection of, 338, 358 Meconin, 298, 335 Meconidine, 294, 301, 308, 326 Meconoisin, 336 Metaphenylenediamine, 86 Metatoluidine, 52 Methacetin, 68, 85 Methocodeine, 167, 296, 324 Methyl chloride, manufacture of, 16 Methyl-ace tanilide, 68, 71 Methyl-alloxantin, 494 Methylamine, 9 reactions of, 10 Methylaniline, 63, 71 nitrosamine, 74 paranitroso-, 74 Methyldiphenylamine, 79 Methylphenacetin, 84 Metaxylidines, 57, 59 Monamines, 3 characters of, 8 distinction of, 7 separation of, 5 Morphine, 294, 309, 326 assay of opium for, 342 colour-reactious of, 302, 305, 813 constitution of, 167, 296, 311 detection of, 313 poisoning by, 356 proportion of, in opium, 333 salts of, 311 INDEX. 579 Morphine, separation of, 305 solubilities of, 301, 310 toxicology of, 355 Morphiometry, 342 JVIurexide, 480 Murexoin, 480 Myoctonine, 202, 222, 225 Naphthylamines, 90 Naphthylamine-sulphonic acids, 9 Naphthylene-diamines, 93 Narceine, 294, 301, 302, 303, 326 constitution of, 299 determination of, 305, 306 Narcotine, 294, 298, 301, 302, 327 constitution of, 167, 298 determination of, 305 Neurine, 19 Nicotine, 179 constitution of, 164 determination of, 161, 170, 182 poisoning by, 183 Nitranilines, 50, 63 Nitrobenzene, recognition of, 67 Nitrosamines, formation of, 7, 74 Nitroso-antipyrine, 34 -dimethylaniline, 75 Nitrous acid, action on monamines, 7 Nornarcotine, 298 Nux vomica, 384 assay of, 385 preparations of, 38^ Orthotoluidine, 90 Opianine, 329 Opiates, composition of various, 357 Opionin, 336 Opium, 332 action of solvents on, 339 adulterations of, 340 alkaloids of, 293, 333 assay of, for morphine, 342 composition of, 333 detection of, 358 extract of, 350 poisoning by, 355 — - proportion of alkaloids in, 333, 335 Opium, tincture of, 350 Opium alkaloids, 293, 333 colour-reactions of, 302 constitution of, 167, 296 proportions of, in opium, 333 separation of, 305 tabular list of, 294 poisonous characters of, 294 Orexin, 122 Orthine, 29 Orthotoluidine, 52 Orthoxylidines, 57, 59 Osazones, 30 Oxidation colour-reactions, 149, 302, 314, 368, 469, 480 Oxyacanthine, 465 Oxydimorphine, see Pseudomorphine Oxyhydrastinine, 470 Oxynarcotine, 294, 329 Papaverine, 294, 301, 302, 304, 306 329 constitution of, 168, 299 Papaverosine, 294, 329 Parabromacetanilide, 68, 71 Paraguay tea, 526 Paraniline, 63 Paraxylidine, 57 Paregoric elixir, 353 Parvoline, 97 Paytamine, 392 Paytine, 392 Piazine, constitution of, 96 Picoline, 97, 107 Picraconitine, 202, 204, 221 Picramide, 51 Pilocarpine, synthesis of, 166 Piperazidine or Piperazine, 106 Piperidine, 106, 164 Piperine, 133, 164 Piturine, 194 Phenacetin, 68, 81 PhenacoU, 68 , Phenethidines, 81 Phenanthridine, 126 Phenazone, 32 Phenylacetamide, 68 580 INDEX. Phenylamine, see Aniline Phenyl-aniline, 73, 79 Pheuyl-carbamine, 46 Phenyl-dimethylpyrazolone, 32 Phenylene-diamines, 63, 86 Phenyl-hydrazides, 28 Phenyl-hydrazine, 27 Phenyl-methylpyrazolone, 31 Phenyl-pyrazolone, 31 Phenyl-urethane, 68, 72 Poisoning by acetanilide, 71 aconitine, 209, 236 aniline, 44, 46 antipyrine, 37 apomorphine, 320 atropine, 248, 261 berberine, 462 brucine, 382 cocaine, 274 cocamine, 286 codeine, 322 _ coniceines, 174 Conine, 175 curare, 388 ethylstrychniura, 19 hemlock, 175 hydracetin, 28 hydrazine, 23 hyoscyamus, 261, 250 laudanine, 325 lobelia, 195 lupinine, 178 metaphenylenediamine, 87 methacetin, 85 nicotine, 183 0]>iates, 357 ojiium, 355 opium bases, 294 paraphenylenediamiue, 57 phenacetin, 83 protopine, 330 pyridine, 98, 103 sparteine, 197 spigeline, 198 strychnine, 372 thebaine, 331 tobacco, 183 Poisoning by toluylene-diaraines, 88 vermin-killers, 380 Porphyrine, 437 Porphyroxine, 296, 330, 335 Precipitants, general, for alkaloids, 134, 158 Propylamine, 12 Protopine, 296, 301, 304, 330 Pseudaconine, 202, 204, 219 Pseudaconitine, 202, 204, 216 anhydro-, 205 saponification of, 204, 218, 234 Pseudocodeine, 323 Pseudomorphine, 294, 301, 302, 330 constitution of, 298 Pseudotropine, 244, 247 benzoyl, 244, 287 Puccine, 296 Pyrazine, 80, 96 Pyrazole, 30, 96 Pyrazolines, 30 Pyrazolones, 30 Pyridine, 96, 99 assay of commercial, 104 bases, 96 -carboxylic acids, 110, 165 detection of, 104 homologues of, 107 salts of, 101. Pyridone, 96 Pyrodine, 28 Pyrone, 96 Pyrrol, 96, 113 methyl-, 114 tetraiodo-, 114 Pyrroline, 96 QUINALDINE, 115 Quinamicine, 427 Quinamidine, 392, 427 Quinamine, 392, 397 constitution of, 169 Qninazoline, 115 Quinetum, 448 Qninicine, 433 Quinidine, 393, 425 determination of, 426, 459 INDEX. 581 Quinidine, reactions of, 397, 426 Quinine, 393 constitution of, 168 decomposition-products of, 168 determination of, in bark, 449, 455 distinction of, from allied bases, 405 formation from cupreine, 169, 398 hydro-, 424 iodosulphate of, 403, 454 iron citrate, 421 precipitation of, as herepathite, 403, 454 reactions of, 400 salts of, 406 sulphate, 406 examination of, 408 impurities in, 408 synthetical isomers of, 169 tannate of, 420 tincture of, 423 wine of, 424 Quinoidine, 433 iodosulphate of, 454 Quiuoline, 114, 116 tetrahydro-, 119 Resopyrin, 37 Rhceadine, 294, 301, 331 Rubidine, 97 Sanguinarine, 295 Salicin, colour-reactions of, 146, 147, 370, 409 Saliityrin, 37 Santonin, colour-reactions of, 148, 370 Scopolamine, 244, 251 Scopoletin, 262 Sina]»ine, 133, 167 Snutf, 193 Solanine, occurrence of, 262 reactions of, 146 Solvents, action of, on opium, 339 on jilant-con.stituents, 151 immiscible, use of, 154 Sparteine, 197 Spigfline, 198 Stramonium, 268 Strychnine, 361 assay of nux vomica for, 385 constitution of, 168 detection of, 374 monobrom-, 363 monosulphonic acid, 363 oxidation-test for, 368, 469 poisoning by, 372 preparations of, 376 ptomaine simulating, 371, 375 reactions of, 364 separation of, from brucine, 366 toxicology of, 372 vermin -killers containing, 376 Strychnos nux vomica, 384 Stylophorine, 296 Sulphanilic acid, 49 Tab bases, 39 Tea, 499 adulterations of, 509 alkaloid in, 419, 492, 504 Arabian, 527 ash of, 511 Assam, 506 Bush, 503 Cape, 503 caper, 520 catechu in, 519 Ceylon, 506, 512 China, 512 chlorophyll in, 505 composition of, 501 essential oil of, 601 exhausted leaves in, 51.? extract of, 505 facing of, 522 foreign leaves in, 522 Indian, 503, 512 infusion of, 505 Japanese, 502, 506 Java, 512 leaves, recognition of, r>23 lie-, 520 mineral adulterants of, 51 moisture in, 504 582 INDEX. Tea, Natal, 503, 612 Paraguay, 526 preparation of, 499 sloe leaves in, 502, 605 tannin in, 515 tasting, 507 Trebizonde, 527 Tannin, in colfee, 529 in tea, 491, 515 reactions of alkaloids with, 135 Tetra-alkylated ammoniums, 18 Tetrahydro-beta-naphthylamine, 92 Tetraiodo-pyrrol, 114 Tetrethyl-ammonium compounds, 19 Thalleioquin reaction, 396, 397, 401 Thalline, 120 ethyl-, 121 Thebaine, 294, 331 colour-reactions of, 302, 331 constitution of, 167, 296 determination of, 306, 307, 332 solubilities of, 301 Theobromine, 492 characters of, 493 constitution of, 492 determination of, 494 in tea, 489 proportion of, in cocoa, 496, 568, 560 Theophylline, 498 Thermifugin, 122 Thermine, 92 Tincture of camphor, compound, 353 aconite, 229 belladonna, 266 conium, 177 hemlock, 177 henbane, 268 nux vomica, 357 opium, 350 quinine, 423 Tobacco, 184 ash of, 186, 188, 189, 190 combustibility of, 190 composition of, 184 extract, 193 nitrogen in, 187, 189, 190 Tobacco, poisoning by, 183 smoke, composition of, 192 Tolidine, 90 Toluidine, commercial, 54 density of, 56 oxalates, 55 phosphates, 54 Toluidines, 41, 51 Toluylene-diamines, 87 Triamidophenol, 85 Trimethylamine, 12 hydrochloride, 16 reactions of, 10 Triphenylamine, 80 Triphenylrosaniline, 64, 66 Tritopine, 294, 301, 332 Tropeines, 243 artificial, 253 saponification of, 244 Tropine, constitution of, 165, 246 benzoyl-, 253 properties of, 246 pseudo-, 247 salicyl-, 253 Truxilline, 271, 281 Uric Acid, colour-reaction of, 480 Veratrine, constitution of, 133, IW Vermin -killers, 378 Vinasses, 13 Viridine, 97 Wine of quinine, 424 Xanthine, constitution of, 473 colour-reaction of, 481 dimethyl-, 473, 492 derivatives of, 473 isolation of, from tea, 473 trimethyl-, 473, 474 Xanthopuccine, 471 Xenylamine, 63 Xylidines, 57, 63 Yerba, 526 Yqpan, 527 ADDENDA.* Page 4. Separation of Methylamines. M. Del6pine, Compt. r&nd. , cxxii. 1064, 1272 ; abst. Jour. Chem. Soc, Ixx. i. 519, 588 ; Ixxii. i. 586. Page 9. Colour-reactions of Aromatic Amines with lead oxide. C. Lauth, Compt. rend., cxi. 975 ; abst. J.C.S., Ix. 433. Page 9. Analysis of mixtures of Ammonia and Methylamines. H. Q u a n t i n, Compt. rend., ex v. 561 ; abst. J.G.S., Ixiv. 104. Page 9. Preparation of Ethylamine and Methylamine. Trill at and Fay oil at. Bull. Soo. Chim., xi. 22; abst. Pharm. Jour., xxiv. 621. Page 9. Preparation of Methylamine. B r o c h e t and C a m b i e r, J. Pharm. et Chim., 1895, ii. 172; abst. J.C.S., Ixx. i. 7. Page 9. Separation and determination of Ammonia and Methylamines. H. Quantin, Ann. de Chim. anal., 1901, vi. 125 ; abst. Analyst, xxvi. 215. Page 12. Preparation ofTrimethylamine. F. Chancel, Compt. rend., cxiv. 756 ; abst. J.C.S., Ixii. ii. 804 ; Bull, Soc. Chim., [3], vii. 405 ; absL J. as., Ixiv. i. 249. Page 15. Separation ofTrimethylamine from Ammonia. H. Fleck, Am^. Chem. Jour., xviii. 670 ; abst. J.C.S., Ixxii. ii. 168. Page 22. Manufacture of Hydrazine. Jour. Soc. Chem. Ind., xi. 370. Page 22. Determination of Hydrazine. H o f m a n n and K ii s p e r t, Bericfde, xxxi. 64 ; abst. Analyst, 1898, xxiii. 95. Page 22. Formation of Hydrazine from hyponitrous Acid. VonBrackel, Berichte, 1900, xxxiii. 2115 ; abst. J.S.G.L, xix. 767. Page 22. Action of Hydrazine on Thiocarbanilide. M. Busch, Berichte, 1899, xxxii. 2815 ; abst. J.C.S., Ixxviii. i. 27. Page 23. Determination of Hydrazine. E. Rimini, Chem. Centr., 1899, ii. 455 ; abst. Analyst, xxiv. p. 269. Pago 23. Use of Hydrazine Salts in the determination of Copper. Jannasch and Biedermann, Ber., 1900, xxxiii. 631 ; abst. Analyst, xxv. 190. Page 23. Formation of explosive Hydrazine-mercury compounds. Hofmann and Marburg, Annalen, 1899, cccv. 191 ; abst. J.S.C.L, xviii. 399. Page 24. Synthesis of Hydrazoic Acid. Tan ata r, ^er., 1902, xxxv. 1810. Page 28. Products of oxidation of Phenyl-hydrazine with Fehling's solution. Strache and Kitt, Monatsh, xiii. 316 ; abst. J.C.S., Ixii. ii. 1322. Page 28. Determination of Phenyl-hydrazine. H. C a u s s e, Bull. Soc. Chim., xix. 147 ; abst. Analyst, 1898, xxiii. 95. •Compiled, at the request of the Author, by A. R. Tankard and S. E. Melling. 584 ADDENDA. Page 28. A colour-reaction of Phenyl -hydrazine. L. Simon, Compt. rend., cxxvi. 483 ; abst. Analyst, 1898, xxiii. 131. Page 30. Use of Phenyl-hydrazine for the determination and differentiation of Sugars. Maquenne, Compt. rend., cxii. 799 ; abst. J.C.S., Ix. 1142. Page 30. Differentiation of Azo- and Hydrazone-compounds by Bromine. H. E. Armstrong, Proc. Chem. Soc, 1899, p. 243 ; abst. J.S.C.I., xix. 73. Page 81. Exhaustive account of the methods of preparation, constitution, and classification of Antipyrine and its derivatives, homologues, and isomers, D. C. Eccles, School of Mines Quarterly, 1901, xxii. 259. Page 32. Antipyrine {B.P., 1898) melts at about 113° C. Page 32. Determination of Antipyrine. C. Kippenberger, Zeit. anal. Chem.,xxxy. 659; abst. Analyst, 1897, xxii. 219. M. F. Schaak, Amer. Jour. Pharm., Ixvi. 321, 631 ; abst. J.S.G.I., 1895, xiv. 199, 773. Page 33. Distinctive colour-reactions of Antipyrine, Tolypyrine, Amido-anti- pyrine, Pyramidou, etc. P. Hoffmann, Zeit.f. Untersuch., 1900, vi. 419 ; abst. J.S.C.L, xix. 778. Page 33. Action of iodine on, and determination of, Antipyrine. J. Bougault, Jour. Pharm. Chim., 1900, xi. 97; abst. J.S.C.L, xix. 269. See also J.S.C.L, 1900, xix. 685. Page 33. Detection of Acetanilide, Phenacetin, etc., in Antipyrine and Quinine. R a i,k o w and Schtarbanow, Oesterr. Chem. Zeit. , 1900, iiL 125 ; abst. Analyst, xxv. 186. Page 88. Preparation of Anilopyrine and of Campho-antipyrines. Mich a el is and Gunkel, Ber., 1901, xxxiv. 723 ; abst. J.S.C.L^ XX. 502 ; H. Wahl, Ber., 1899, xxxii. 1987 ; abst. J.S.C.L, xviii. 783. Page 38. Acetopyrine. Bolognesi and Wolfmann, abst. Pharm. Jov/r. , 1901, ii. 405. Page 40. New method of preparation of Aniline and analogous bases. Sab a tier and Senderens, Compt. rend., cxxxiii. 321 ; abst. J.S.C.L, 1901, XX. 978. Page 43. New Synthesis of Aniline. G. F. Jaubert, Compt. rend., cxxxii. 841 ; abst. J.S.C.L, 1901, xx. 464. Page 47. Volumetric method for the determination of Aniline. ]\1. Francois, J. Pharm,. Chim., 1899, ix. 521; abst. Analyst, xxiv. 245; G. Denig^s, /. Pharm. Chim., 1899, x. 63; abst. J.S.C.L, xviii. 866. Page 53. Determination of Para-toluidine. G. A. Schoen, Zeit. anal. Chem., xxix. 86 ; abst. J.C.S., Iviii. 839. Page 54. Separation and determination of Aniline and Toluidine. D o b r i n e r and Schranz, Zeit. anal. Chem., xxxiv. 734; abst. J.S.C.L, 1896, XV. 298. Page 54. Examination of commercial Toluidine. F. F. Raabe, Chem. Zeit, XV. 116 ; abst. J.S.C.L, x. 488. Page 57. Properties of Paraxylidine. R. Michael, Berichte, xxvi. 39; abst. J.C.S., Ixiv. i. 198. Page 57. A method of separation of the various isomerides contained in ordinary commercial Xylidine. Hodgkinson and Limpach, Jov/r. Chem, Soc., 1900, Ixxvii. 65. Page 58. Nitro- and Bromo-derivatives of the Xylidines. N o e 1 1 i n g, ADDENDA. 585 Braun, and Thesraar, B^r., 1901, xxxiv. 2212; abst. J.S.C.I., XX. 797. Page 59. Determination of commercial Xylidines. W. Vaubel, Zeit. anal, Chem., xxxvi. 285 ; abst. J.S.C.I., 1897, xvi. 639. Page 61. Analysis of Aniline Oils and Aniline Salt. Leibmann and Studer, J.S.C.L, 1899, xviii. 110. Page 63. Assay of Alkyl-aniliues, W. Vaubel, Chem. Zeit., xvii. 465; abst. J.C.S., Ixiv. 605. Page 64. Analysis of Aniline Oils. H. Reinhardt, Chem. Zeit., xvii. 413 ; abst. Analyst, 1893, xviii. 150. Page 68. Micro-chemical tests for Acetanilide, Phenacetin, etc. S c h o e p p, Pharm. Zeit., xlii. 106 ; abst. J.S.C.L, 1897, xvi. 361. Page 68. Detection of Acetanilide in synthetical remedies. F. X. Moerk, Amer. Jour. Pharm., 1896, p. 394. Page 68. Properties of Phenocoll hydrochloride. S c h e r i n g, Apoth. Zeit., vi. 249 ; abst. J.S.C.L, x. 790. Page 68. Characters of Acetanilide. F. B. Power, Pharm. Jour., 1900, Ixv. 145. Page 69. Examination of Acetanilide. C. Piatt, Jour. Anal, and App. Chem., vii. 77 ; abst. Analyst, 1896, xxi. 138. Page 69. Detection of Acetar.ilide. F. X. Moerk, Amer. Jour. Pharm., 1896, p. 389 ; abst. Analyst, xxi. 291. See also Analyst, 1896, xxi. 69. Page 75. Action of acetic anhydride on Dimethylaniline. Reverdin and de hi Harpe, Bull. Soc. Chim., vii. 211 ; abst. J.C.S., Ixiv. i. 23, Page 81. Dulcine. See Vol. III. Pt. iii. page 279 and Addenda. Page 82. Preparation and characters of Phenacetin, Pharm. Jour. , 1 899, i. 512. Page 82. A reaction for Phenacetin. Autenreith and Hinsberg, Arch, de Pharm., cexxix. 456 ; abst. Analyst, 1892, xvii. 56. Page 82. Properties of Phenacetin. G. Cohn, Annalen, 1899, cccix. 233; abst. J.G.S., Ixxviii. i. 29. Page 83. Colour-reactions for Phenacetin, Methacetin, etc., in mixtures. T. G. Selmi, Chem. Zeit., xvi. 368 ; abst. J.S.C.L, 1893, xii. 466. Page 83. Gu asti states that Schwartz's test for the detection of Acet- anilide is unreliable. See J.C.S., Ixvi. 432. Page 85. Preparation of Phenacyl-Phenacetin. C. Goldschmidt, Chem. Zeit, 1901, XXV. 628; abst. J.S.C.L, xx. 929. Page 88. Pliysiological action of Toluylene-diamine. W. Hunter, Jour. Pathol, and Bacterial., 1895, p. 259 ; abst. J.C.S., Ixviii. ii. 456. Page 89. Determination of Benzidine and Tolidine. W. Vaubel, Zeit. anal. Chem., xxxv. 163 ; abst. J.C.S., Ixx. ii. 507. Page 89. Colour-reaction for the detection of Benzidine and Tolidine. J. Wolff, Chem. Centr., 1899, ii. 569 ; abst. J.C.S., Ixxviii. ii. 119. Page 91. o-Naphthylamine has not much smell, the disgusting odour com- monly ascribed to it being mainly due to impurities. A pure article having a melting point of 47° C. is now made on a commercial scale. Page 92. Assay of Naphthylamine-sul phonic acids. W. Vaubel, Chem. Zeit., xvii. 1265 ; abst. J.C.S., Ixvi. ii. 74. Page 92. Preparation of /3-Naphthylamine-sulphonic acid. A. G. Green, J.S.C.L, 1889, viii. 878; 1890, ix. 934. 586 ADDENDA, Page 101. Action of chloranil on Pyridine. H. Imbert, Bull. Soc. Chim., 1898, xix. 1008; abst. J.C.S., 1899, Ixxvi. i. 633. Page 102. The Chlorine derivatives of Pyridine. Sell and D o o t s o n, Jour. Chem. Soc, 1898, Ixxiii. 432, 442 ; 1899, Ixxv. 979; 1900, Ixxvii. i. 233. Page 103. Action of cadmium salts on Pyridine and Piperidine. R. Varet, Compt. rend., cxv. 464; abst. J.C.S., Ixiv. i. 43. Page 103. Action of tannin on Pyridine and Piperidine. 0. deConinck, Compt. rend., cxxiv. 506 ; abst. J.S.G.L, 1897, xvi. 470. Page 1C6. Piperidine and Piperazine. See also Vol. III. Pt. iii. pp. 38, 194. Page 107. Properties of Piperidine Urate. Tunnicliffe and Rosen- heim, Brit. Med. Jour., 5th February, 1898. Page 107. Potassio-iodide of bismuth precipitates Piperidine from its solu- tions on concentration and cooling, in the form of thin, transparent, yellow hexagonal plates, of characteristic microscopic appearance. Page 114. Source and properties of "lodol." k. H viW&t, Monit. Scient.f 1892, p. 338 ; abst. J.S.G.L, xi. 1030. Page 114. Action of nitric acid on *'Iodol." H. Cousin, Jour. Pharm, Chim., xiii. 269 ; abst. J.S.C.I., 1901, xx. 497. Page 128. Localisation of Alkaloids in Plants. Wijsmann, Pharm. Zeit., xliii. 691; abst. Pharm. Jmr., 1899, i. 337. Page 129. Micro-chemical recognition of Alkaloids. L. Erreva, Pharm. Jour., xxiii. 48. H. B a r t h, Pharm. Jour., 1898, ii. 635 ; 1899, i. 360. Vadam, abst. J.S.C.I., 1897, xvi. 165. Page 130. Titration of Alkaloids. L. F. Kebler, Amer. Jour. Pharm., Ixvii. 499 ; abst. Chem. News, Ixxiii. 298. H. Brown, Pharm. Jour., XXV. 1180. Page 130. Action of acids on Alkaloids. A. H. A 1 1 e n, Chem. News, Ixvi. 259. Page 130. Acidimetry of Alkaloids. E. Fali feres, Compt. rend., cxxix. 110 ; abst. Pharm. Jour., 1899, ii. 295. Page 131. Volumetric determination of Alkaloids. E. L6g er, Compt. rend., cxv. 732; abst. J.S.C.I., 1893, xii. 470. Page 131. Titration of Organic Bases with methyl-orange. G. Lunge, Chem. Ind., xvi. 490 ; abst. J.S.C.I., 1894, xiii. 667. Page 134. Reagent for Alkaloids. Orlow & Horst, J.^.C.Z, 1901, xx. 511. Page 135. Tannates of Alkaloids are soluble in glycerin. This allows of a ready separation of the alkaloids from albumin. (C. Kippenberger, Analyst, 1895, xx. 201.) Page 1 37. G. B e r t r a n d (abst. Pharm. Jour. , 1899, i. 503) strongly recom- mends Silico-tungstic acid as a precipitant of Alkaloids. Page 137. Determination of Alkaloids volumetrically by iodine solution. 0. Linde, ^rcA. Pharm., 1899, ccxxxvii. 172; abst. J.C.S , IxxvL ii. 534; C. Kippenberger, Zeit. anal. Chem., 1899, xxxviii. 230, 280 ; absts. J.C.S. , Ixxvi. ii. 534, 584 ; M. Scholtz, Zeit. anal. Chem., xxxviii. 278 ; abst. J.C.S., Ixxvi. ii. 584. Page 138. Delicacy of M a r m e's reagent for Alkaloids. S. V e r v e n, Ann. de Pharm., xiii. 145 ; abst. Analyst, 1897, xxii. 241. Page 138. Alkaloidal Periodides. Determination of Alkaloids. P r e s c o 1 1 and Go r din, ATner. Jour. Pharm., Ixx. 439; Ixxi. 14, 18; absts. Analyst, 1898, xxiii. 324 ; 1899, xxiv. 74, 75. ADDENDA. 58? Page 139. Volumetric determination of Alkaloids, L. B a r t h e, Compt. rend., cxv. 512 ; abst. Cliem. News, Ixvi. 223. Page 139. Volumetric determination of Alkaloids. P. C. Plugge, Compt. rend., cxv. 1012 ; abst. J.C.S., Ixiv. ii. 199. Page 161. Determination of Alkaloids. Grandval and Lajoux, J. Pharm. et Chim., xxviii. 99; abst, J.C.S., Ixiv. ii. 608. H. A. D. Jowett, Pharm. Jour., 1899, i. 377. Page 151. Examination of decomposed human remains of Alkaloids. 0. Kippenberger, Zeit. anal. Chem., xxxiv. 294 ; abst. J. O.S., 1895, Ixviii. ii. 465. Page 151. Determination of Alkaloids. K. Dieterich, Pharm. Zeit.^ xliv. 242; abst. Pharm. Jour.y xxv. 962. Page 151. Isolation and determination of Alkaloids. C. Kippenberger, Zeit. anal. Chem., xxxv. 10,407; abst. J.C.S., Ixx. ii. 681, 682; Analyst, xxi. 191. F a rr and Wright, Pharm. Jour., 1897, i. 202. Page 151. Alkaloidal determinations. G o r d i n and Prescott, Amer. Jour. Pharm., 1899, Ixxi. 514. Page 151. Carbon tetrachloride as a solvent in the estimation of Alkaloids. J. Schindelmeiser, Pharm. Zeit., xlvi. 193 ; abst. Pharm. Jour., 1901, 1. 459. Page 151. Determination of the Solubility of Alkaloids. R. A. Hatcher, Amer. Jour. Pharm., 1902, Ixxi v. 134. Page 151. Absorption of Alkaloids by Charcoal. H. Laval, abst. Pharm. Jour., 1900, ii. 213. Page 151. Determination of Alkaloids. Pharm. Jour., 1900, ii. 286. Page 154. Employment of Chloral Hydrate in the estimation of Alkaloids. E. Schaer, Zeit. anal. Chem., 1899, xxxviii. 469; abst. J.C.S., Ixxviii. ii. 57. Page 154. Detection of Alkaloids. Hilger and Jan sen, Zeit. anal. Chem., xxxvi. 344; abst. J.C.S., Ixxii. ii. 436. Page 154. Action of chloroform and other solvents on Alkaloidal salts. E. Schaer, Pharm. Jour., 1900, i. 308. Page 160. For the separation of Alkaloids in forensic cases, C. Kippen- berger agitates the alkaloidal solution, first with sulphuric acid and chloroform ; then with caustic soda and chloroform ; next with sodium bicarbonate and alcoholic chloroform ; and finally saturates with sodium chloride and agitates with ether-chloroform, which last treatment re- moves Strophanthin. {Zeit. Awd. Chem., 1895, p. 294; abst. Analyst, 1895, XX. 201.) Page 160. Clau s' method of Tea-assay is valueless. Compare page 486. Page 161. Lloyd's process is stated to give more reliable results than any other rapid method of Alkaloidal Assay (Nichols and Norton, Jour. Anal, and Appl. Chem., vi. 162; abst. J.S.C.I., 1893, vii. 68). Page 163. History of the constitution of the Alkaloids. A. R. L. Dohme, Amer. Jour. Pharm., 1900, Ixxii. 9. Page 173. New test for Conine. Van Sen us, abst. Analyst, xv. 79. Page 174. Preparation and properties of Ooniceine, Conine, etc. Lellmann and M tiller, Berichte, xxiii. 680; abst. J.C.S., Iviii. 802. 588 ADDENDA. Page 175. Detection of Conine in cases of poisoning. Vitali and Stropps, abst. Analyst, 1900, xxv. 233. Page 176. Volumetric determination of Conine and Nicotine in the same solution. G. H e u t, Arch, de Pharm., cexxxi. 376 ; abst. J.G.S., Ixiv. 608. Page 176. Assay of Con ium Seed or Leaves. H. M. Gordin, Amer. Jour. Pharm.y 1901, Ixxiii. 217; abst. Analyst, 1901, xxvi. 297. Page 179. Chemistry of Tobacco. Pictet and Rotschy, Chem. Zeit.^ xlvi. 118 ; abst. Pharm. Jour., 1901, i. 424. Page 180. One c.c. of normal hydrochloric or sulphuric acid is neutralised by 0'162 gramme of Nicotine, when methyl-orange is used as the indicator. Page 181. Detection of Nicotine. J. Schindelmeiser, Pharm. Centr., xl. 704 ; abst. Pharm. Jour.^ 1900, i. 1. Page 182. Determination of Ammonia and Nicotine in Tobacco. V. Vedrbdi, Zeit anal. Chem., 1895; abst. Analyst, 1895, xx. 255. R. K is sling, Zeit. anal. Chem., xxxiv. 731; abst. J.S C.I., 1896, XV. 300. A. Pezzolato, abst. J.C.S., Ix. 771. Page 182. Determination of Nicotine in Tobacco. C. C. Keller, Chem. Centr.^ 1898, ii. 388; abst. J.C.S., 1899, Ixxvi. ii. 193. J. Foth, Chem. Zeit., 1901, xxv. 610 ; abst. Pharm. Jour., 1900, i. 747. Page 184. Analysis of the Tobacco-plant. R. J. Davidson, abst. J.C.S., Ixiv. ii. 38. Page 184. Three new Tobacco Alkaloids. Pictet and Rotschy, Compt. rend., exxxii. 971. Page 189. Determination of non-volatile organic acids in Tobacco. R. Kis sling, Chem. Zeit., 1899, xxiii. 2 ; abst. J.C.S., 1899, Ixxvi. ii. 821. Page 190. Composition of Tobaccos. H. B. Cox, Phnrm. Jour., xxiv. 589. Page 190. Paratfins in Tobacco-leaf. Thorpe and Holmes, Proe. Chem. Soc, 1901, xvii. 170 ; abst. J.S.C.I., 1901, xx. 758. Page 192. Constituents of Tobacco-smoke. H. Thorns, Pharm. Centr., xl. 706 ; abst. Pharm. Jour., 1900, i. 69. Page 192. Composition of Tobacco-smoke. A. Gautier, Compt. rend.f cxv. 992 ; abst. J.C.S., Ixiv. i. 226. Page 193. Examination of Tobacco-extract. J. Pinette, Chem. Zeit., xvi. 178 ; Analyst, 1892, xvii. 178. Page 195. Tincture of Lobelia. J. F. Liver see ge, Pharm. Jour., Iv. 141. Page 198. For papers on the Aconite Alkaloids by Dunstan, Umney, DunstanandCarr, etc., see Jour. Chem. Soc, Ixi. 385, 393 ; Ixiil 443, 491, 991 ; Ixv. 176, 290 ; Ixvi. 308 ; Ixx. i. 192 ; Ixx. ii. 283 ; Ixxi. 35U. Jour. Soc. Chem. Ind., xi. 366. Pharm. Jour., xxii. 488 ; xxiii. 86, 625, 765, 1045; xxiv. 581, 729, 735, 891, 910, 935; xxv. 773, 860, 928, 1117 ; 1896, i. 121 ; 1898, i. 323. Page 199. Structure of various Aconite Roots. A. Goris, abst. Pharm. Jour., 1901, ii. 577. Page 202. A contribution to the knowledge of Aconite bases. Dunstan and Resid,J.C.S., 1900, Ixxvii. 45. ADDENDA. 589 Page 207. Formula and characters of Aconitine. F. B. P o w e r, Pharm. Jour., 1900, ii. 147. Page 226. The extraction, composition, and properties of Atisine and its salts. H. A. D. J o w e 1 1, J.C.S., Ixix. 1518. Page 228. Determination of Aconitine in aconite extracts. H. Ecalle, Jour. Pharm. Chim., 1901, xiv. 97; abst. Analyst, xxvi. 322; abst. Pharm. Jour., 1901, ii. 27. Page 236. Cadaveric Alkaloid resembling aconitine. A. Mecke, Chem. Centr., 1899, ii. 256 ; abst. J.C.S., Ixxviii. ii. 120. Pages 244 and 250. 0. Hesse has shown that Hj^oscine probably has the formula C17H21NO4, and by saponification yields the base o seine CgHigNOg, and not pseudotropine {Ann. der Chemie, cclxxi. 100 ; abst. Pharm. Jour., [3], xxiii. 221). Page 246. According to S. V r e v e n, Cadmium-Potassium Iodide gives with Tropine, in slightly acid solutions, a cr3'stalline precipitate consisting of well-formed hexagonal tables, which melt above 200° C. to a clear liquid. With a faintly acid solution of phosphomolybdic acid, tropine also yields a yellowish precipitate of microscopic needles, which on warming turns green, and then decomposes without melting. These reactions readily distinguish tropine from the four principal mydriatic alkaloids of the Solanacece, which, with cadmium potassium iodide, give either amorphous precipitates or crystalline precipitates of quite different appearance ; while with phosphomolybdic acid they yield amorphous ])recipitates only. Page 247. Some new Gold Salts of the Mydriatic Alkaloids. H. A. D. J o w e 1 1, /. a /S'. , Ixxi. 679. Page 247. Notes on Solanace us Bases. 0. Hesse, Pharm. Jour., 1900, i. 117 ; abst. J.C.S., 1900, Ixxviii. i. 50. Page 249. Alkaloids of Hyoscyamus muticus and Datura Stramonium. Dun stan and Brown, J.C.S., 1901, Ixxix. 71. Page 250. HyoscyamineSulphate,B2H2S04 + 2H20(5.P.,1898) melts at 206° C. Page 251. For information respecting Apo-atropine, Atropamine, Bella- donine and Scopolamine, see E. Schmidt and 0. Hesse, abst. Pharm. Jour., [3], xxii. 1021 ; xxiii. 221 ; [4], 1899, i. 383. Page 254. Separation of Atropine and Hyoscyamine. 0. Hesse, abst. Pharm. Jour., [3], xxiii. 201. Page 258. Test for distinguishing Atropii.-e from Strychnine. D. Vitali, Chem. Centr., 1894, ii. 816; abst. J.C.S., 1895, Ixviii. ii. 467 ; Zeit. anal. Chem., xxxviii. 134; abst. J.S.G.L, 1899, xviii. 404. Page 261. Toxicological detection of Atropine and its allies. Ciotto and Spica, abst. J.C.S., Ix. 772. Page 261. Detection of Atropine in forensic cases. P. Sol stein, abst. Analyst, 1897, xxii. 162. Page 262. Note on the B. P. standardisation of Belladonna. J. A. Dewhirst, Pharm. Jour., 1900, i, 358. Page 263. Determination of Alkaloids in the leaves of Datura Stramonium* E. Schmidt, abst. Pharm. Jour., 1900, i 22. Page 264. Assay of Belladonna Root. W. A. P u c k n e r, abst. Pharm. Jour., 1898, ii. 97. E. Dowzard, Pharm. Jaur., 1899, i. 309. 590 ADDENDA. Page 265. Official processes for the assay of Belladonna and its preparations. F. C. J. Bird, Pharm. Jour., 1899, i. 432 ; 1900, i. 532, 690 ; 1900, ii. 195. Page 265. Assay of Belladonna Plasters. C. E. Smith, Amer. Jour. Fharm., Ixx. 182. F. C. J. Bird, abst. Pharm. Jour., 1899, ii. 146. Page 265. Assay of Belladonna Root and its solid extract. A. W. Clark, Amer. Jour. Pharm., 1901, Ixxiii. 22. Page 266. Assay of liquid extract of Belladonna. H. Wilson, Pharm. Jour., 1898, i. 450. Page 269. Official extracts of Belladonna. E.White, Pharm. Jour. , 1901, i. 196 ; Brit. Pharmacopcsia, 1898, p. 103. Page 270. Constitution of Coca Alkaloids. W. Garsed, Pharm. Jour., 1901, ii. 500, 519. Page 272. Isolation of Cocaine from accompanying alkaloids. Einhorn and Will Stat ter, abst. J.C.S., Ixvi. i. 478. Page 274. Test for Cocaine. Scharges, Chem. Centr., 1893, ii. 888; abst. J.C.S., Ixvi. ii. 127. Page 274. Properties of Eucaine and Cocaine. G. Vulpius, abst. J.S.C.I., 1896, XV. 679, 745. P. S il e x, abst. J.S.C.L, 1897, xvi. 631. Page 274. Reactions of Cocaine. J. C. Stead, Pharm. Jour., xxii. 902. A. Kub orne, Pharm. Centr., xxxiii. 411 ; abst. J.S.C.L, 1893, xii. 380. Page 274. Detection of Cocaine in poisoning cases. H. W. Glasenap, Chem. Centr., 1894, ii. 220 ; abst. J.C.S., 1895, Ixviii. ii. 336. Page 27i. For the detection of Cocaine, A. Kub orne, Jun. {Chem. News, Ixvii. 254), recommends that 1 c.c. of nitric acid (1'42 sp. gr.) be added to the substance in a porcelain dish, and the liquid evap- orated at 100° C. When cold, a drop of alcoholic potash is added. No colour is produced in the cold (distinction from atropine), but when heated on the water-bath an intense violet coloration is suddenly produced. Page 274. A new test for Cocaine. G. L. Schaf er, J. Amer. Chem. Sac, 1899, xxi. 634 ; abst. J.C.S., Ixxvi. ii. 715. Page 274. The Chromic Acid test for Cocaine. G. L. S chafer, Pharm. Jour., 1899, ii. 66. Pages 277 and 283. Reactions of Cocaine and Ecgouine. D. Y itali, abst. J.C.S.,\x. 1561. Page 280. Characters of Cocaine hydrochloride. Paul and C o w n 1 e y, Pharm. Jour., 1898, i. 586. Page 280. Test for the purity of Cocaine salts. G. L. Schafer; A. J. C o wn 1 e y ; Pharm. Jour., 1899, i. 336. Page 280. A new Alkaloid in Coca leaves. G. L. S c h a f er, abst. Pharm. Jour., 1899, i. 359. Page 280. Maclagan's ammonia test for the purity of Cocaine hydro- chloride. See absts. Pharm. Jour., 1898, i. 449, 473 ; 1898, ii. 26 ; 1899, i. 431. Page 281. Estimation of Cocaine. Garsed and Collie, J.C.S., 1901, Ixxix. 675 ; abst. Pharm. Jour., 1901, i. 553 ; Pharm. Jour., 1901, ii. 222, 254 ; abst. Analyst, 1901, xxvi. 322. ADDENDA. 591 Page 284. Identification and properties of o- and )8-Eucaine. C. L. Parsons, Jour. Amtr. Chem. Soc, 1901, xxiii. 885; abst. Analyst, 1902, xxvii. 123. Page 287. Properties of Ben zoyl-pseudotro pine and its salts. Pharm. Jour., [3], xxiii. 241. Page 292. Assay of Coca leaves. "W. R. Lamar, Amer. Jour. Pharm., 1901, Ixxiii. 125. Page 293. Assay of fluid extract of Coca. C. T. K i n g s 1 e y, Amer. Jour. Pharm., 1896, p. 609 ; abst. Analyst, 1897, xxii. 77. Page 293. The author was indebted to Mr D. B. Dott for perusal and correction of the section on Opium Alkaloids. Page 295. Assay of Sanguinaria and its preparations. C. H. La Wall, Amer. Jour. Pharm., 1896, p. 305. Page 295. Reactions of Chelidonine with phenols. J. A. Battandier, Compt. rend., cxx. 270 ; abst. J.C.S., 1895, Ixviii. ii. 336. Page 295. Alkaloids of Sanguinaria, Eschscholtzia and Glaucium Luteum. R. Fischer, abst. Pharm. Jour., 1901, ii. 385. Page 295. Alkaloids of Chelidonium. Schmidt, abst. Phorm. Jour., 1901, ii. 361. Win tern, abst. Pharm. Jour., 1901, ii. 40.^.. Page 295. Characters of Alkaloids of Chelidonium. G. B o 1 1, Pharm. Jour., 1901, ii. 317. Page 296. Alkaloids of Bocconia cordata. M u r r i 1 1 and Schotterbeck, Pharm. Jour., 1900, ii. 34. Page 300. Solubility of Morphine and Narcotine. E. L. Patch, Amer. Jour. Pharm., 1898, p. 553. Page 305. Detection of Alkaloids by the Stas-Otto method. R. Otto, Arch, de Pharm., ccxxxiv. 317 ; abst. J.G.S., Ixx. ii. 508. Page 309. Researches on Morphine. Schry ver and Lees, J".C.*S'., 1900, Ixxvii. 1024 ; Ixxix. 563 ; abst. Pharm. Jour., 1901, i. 713. Page 312. Derivatives of Morphine. (Merck's Report, 1898.) Pharm. Zeit., xliv. 117 ; abst. J.S.C.L, 1899, xviii. 395. Page 312. Properties of Dionine, L. Hesse, Pharm. Centr., xl. 1 ; abst. Analyst, 1899, xxiv. 128. Page 312. Crystalline characters of Morphine Hydrochloride. F. B. P o w e r, Pharm. Jour., 1900, ii. 151. Page 313. Colour-tests for Morphine. G. B r u y 1 a n t s, J. Pharm. et Chim., May 1st, 1895 ; abst. Pharm. Jour., xxv. 1123. Page 313. Reactions for Morphine. G. Bruylants, Bull. Soc. Chim., xiii. 497 ; abst. J.C.S., Ixx. ii. 132. Page 315. The Furfural reactions of Alkaloids. N. W e n d e r, Chem. Zeit., xvii. 950; abst. J S.C.I., 1893, xii. 869. Page 316. The determination of Morphine. C. Kippenber ger, Zeit. anal. Chem., xxxv. 421 ; abst. Analyst, xxii. 42. Page 316. The determination of Alkaloids in Narcotic extracts. J. H. Schmidt, Chem. Zeit., xvi. 1275 ; abst. J.S.C.L, 1893, xii. 470. Page 316. Titration of Morphine. Cannepin and van E i j k. Bull. Soc. Chim., ix. 437 ; abst. J.C.S., Ixiv. ii. 607. Page 316. Determination of Morphine in Opium. M on temartini and Trasciatti, abat. Analyst, 1899, xxiv. 264 ; abst. J.C.S., 1899, Ixxvi. 692 ADDENDA. ii. 619. G r d i n and P r e s c o 1 1, Arch. Pharm., ccxxxvii. 380 ; abst. J.C.S., 1899, Ixxvi. ii. 714. Page 316. Extraction of Morphine with immiscible solvents. Puckner, J. Amer. Chem. Soc, 1901, xxiii. 470. Pago 317. Ferricyanide test for Morphine. Schaer, Arch, de Pharm.y ccxxxiv. 348 ; abst. Pharm. Jour., 1896, ii. 61. Page 317. Detection and determination of Morphine. F. Wirt hie, abst. J.S.C.L, 1901, XX. 511 ; abst. Analyst, 1901, xxvi. 236. Page 317. Determination of Morpliine. Orlow and Horst, abst. J.S.C.L, 1901, XX. 511. Page 320. Heroin (Di-acetyl morphine). Harnack, abst. Pharm. Jour., 1899, ii. 65. Page 820. Dionine, a new morphine derivative. L.Hesse, abst. J.S.CL, 1899, xviii. 295. Page 321. Examination of Codeine. Tambach and Henke, Pharm. Centr., xxxviii. 159 ; abst. Analyst, xxii. 219. Page 321. On the Pharmacopceial tests for Codeine. F. B. Power, Pharm. Jour., 1900, ii. 149. Page 323. Separation of Codeine and Morphine. L. Fouquet, J. Pharm. et Ghim., xvii. 49 ; abst. J.S.C.L, 1897, xvi. 159. Page 325. Laudanosine, its production and constitution. Pictet and Athanascscu, Ber., xxxiii. 2346 ; Pharm. Jour. , 1900, ii. 572. Page 326. According to E. Levoy, thermo-chemical measurements show that Narceine is the weakest of the opium bases. Page 327. Reactions for Narceine and Papaverine. C. Kippenberger, Zeit. anal. Chem., 1895, p. £94 ; abst. Analyst, 1895, xx. 201. Page 331. The chemistry of Thebaine. M. F r e u n d, BerichU, 1897, p. 11 ; abst. J.C.S., Ixviii. i. 117 ; Ixxii. i. 494. Page 333. Amount of Morphine in dried Opium. E. Dowzard, Pharm. Jour., 1900, ii. 99. Page 340. Determination of starch and strontium sulphate in Opium. K e b 1 e r and L a W a 1 1, Amer. Jour. Pharm. , 1897, p. 244. Page 342. Assay of 0]num and its preparations. Grandval and L a j o u x, J. Pharm. et Chim., 1897, p. 153 ; abst. J.S.C.L, 1897, xvi. 265. G. Looff, Apoth. Zeit., 1896, ii. 192; abst. Analyst, xxi. 163. F. X. Moerk, Amer. Jour. Pharm., 1877, page 344. E J. Millard, Pharm. Jour., xxiv. 831. D. B. Dott, Pharm. Jour., 1892, p. 7J6 ; 1894, p. 847. G. Coull, Pharm. Jour., 1894, p. 954; 1895, ii. 75. G o r d i n and Present t. Arch. Pharm. , ccxxxvii. 380 ; abst. J. S. C. L , 1900, xix. 784. W. R. Lama r, Am^r. Jour. Pharm., 1900, Ixxii. 36. W. Stoeder, Pharm. Cevtr., xlii. 518 ; abst. Pharm. Jour., 1902, i. 1. H. Thorns, Chem. Centr., 1898, ii. 136; abst. J.S.C.L, 1899, Ixxvi. ii. 194. Page 350. Manufacture of Chinese Extract of Opium. J. Calvert, Pharm. Record, xxx. 822 ; abst. Pharm. Jour., 1901, i. 27. Page 350. Liquid Extract of Opium [P.P., 1898) contains 075 gramme of morphine per 100 c.c, and has a specific gravity between 0'985 and 0-995. Page 351. Assay of Laudanum. L. F, Kebler, Amer. J. Pharm., 1893, p. 209. ADDENDA. 593 Page 356. Tests for Morphine in forensic cases. D. L. D a v o 1 1, Jun. , Amer. Chem. Jour., xvi. 799 ; abst. Analyst, xx. 38. J. B. N ag el voort, Amer. Jour. Fharm., 1896, p. 374. Page 358. Detection of poisoning by Opium. Mercke, abst. J.O.S., Ixxviii. ii. 180. Page 361. Nux Vomica preparations are said to contain a minute trace of Copper. Page 363. Liquor Strychninse Hydrochloridi (B. P., 1898). Martindale, Lunan, and others, Fharm. Jour., 1898, 1. 587; 1898, 11. 19, 43, 67 ; 1899, i. 120. Page 363. Water of crystallisation of Strychnine Hydrochloride. D. B. Dott, Pharm. Jour., 1899, i. 58 ; W. H. Martindal e, ^&^c^., p. 120. Page 363. Interaction of Strychnine Hydrochloride and Potassium Arsenate. J. R. H ill, Fharm. Jour., 1900, i. 184. Page 363. Action of Chloroform on Strychnine salts. J. R. Hill, Pharm. Jour., 1900, i. 185. Page 363. Strychnine Hydrochloride, BHCI + 2H2O, is official in the Brit. Pharmacoposia of 1898. "W. H. Martindale regards the com- mercial salt as a combination or mixture of an equal number of mole- cules of BHC1,2H20 and BHCl,liH20,containing7'84 percent, of water. Page 364. Alkaloidal content of Strychnine salts. W. Duncan; G. Coull ; Fharm. Jour., xxii. 843, 846. Page 364. According to D. B. Bott (Fharm. Jour., [3], xxiii. 197), the solubility of Strychnine Hydrochloride in cold water is 1 in 35. Page 364. Detection of Strychnine in forensic cases, A. S. Cushman, Chem. Centr., 1894, ii. 461 ; abst. J.C.S., 1895, Ixviii. ii. 542. Page 364. Behaviour of Iodoform and Chloroform with Strychnine. P. F. Trowbridge, abst. J.G.S., Ixxviii. i. 187. Page 367. The following Alkaloids are not precipitated by potassium ferro- cyanide : — atropine, codeine, emetine, narceine, sparteine, " veratrine." Page 367. Separation of Strychnine from Brucine. W. Stoeder, Chem. Centr., 1899, i. 506 ; abst. J.C.S., Ixxvi. ii. 715. Page 367. Determination of Strychnine. Farr and Wright, Pharm. Jour., 1900, ii. 82, 140. Page 368. Action of sulphuric acid on Strychnine. Bailey and Lange, Amer. Jour. Fharm., 1898, p. 18. Page 368. Examination of the Oxidation-test for Strychnine. Mason and Bowman, Amer. Chem. J(mr.,xyi. 824 ; abst. J.S.C.I., 1895, xiv. 313. Page 368. Detection of Strychnine. H. Beckurts, Arch. Fharm.', abst. Fharm. Jour., xxiv. 2. Page 383. Colour-reactions of Brucine. P. Pich ard, Compt. rend., cxxiii. 590 ; abst. Analyst, 1897, xxii. 47. Page 384. The Brucine and Strychnine in nux vomica seeds exist in separate cells. Sau van, J. Fharm. et Chim., vi. i. 497 ; abst. Fharm. Jour., XXV. 1090. Page 385. Assay of Nux Vomica and its Preparations. See Brit. Fharmxi- copoiia, 1898, pp. 117, 118. Also F. C. J. Bird, Fharm. Jour., 1900, ii. 214, 574. E. R. Squibb, J. Amer. Chem. Soc, 1899, xxi. 351. F. H. A 1 cock, Pharm. Jour., 1900, i. 174. VOL. III. PART II. 2 P 594 ADDENDA. Page 386. Determination of Nux Vomica Alkaloids. C. C. Keller, Apoth. Zeit., viii. 542 ; abst. J.S.O.L, 1894, xiii. 1105. Page 388. Most specimens of Curare contain methyl-strychnine, which is one of the most active ingredients. See E. Anquetil, abst. Pharm. Jour., xxiii. 624. Page 391. Materia Medica of Cinchona Bark. Pharm. Jour., 1901, i. 552. Page 391. Formation of the Cinchona Alkaloids. J. C. Lotsy, abst. Pharm. Jour., 1900, ii. 689 ; abst. J.S.O.L, 1901, xx. 498. Page 396. Per-bromides of Cinchona Alkaloids. A. Christensen, Chem. Centr., Ixxii. 1377 ; abst. Pharm. Jour., 1901, ii. 313. Page 396. Test for Cinchona Alkaloids. Jaworowski, /. Pharm. et Chim., 1896, p. 553 ; abst. J.C.S., Ixx. ii. 629. Page 401. Modifications of the Thalleioquin reaction. J. Ducommon, Chem. Zeit., 1895, p. 214 ; abst. Analyst, xx. 234. F. S. H y d e, Arrier. Chem. Jour., xix. 331 ; abst. Analyst, 1897, xxii. 266. Page 401. A reaction for Quinine. C. Carrez, J. Pharm. et Chim., 1896, p. 253 ; abst. J.C.S., Ixx. ii. 584. Page 402. Determination of Quinine. L. Bar the, Compt. rend,., cxv. 1085; abst. J.S.C.I., 1893, xii. 380. Page 403. Titration of Quinine. L. F. Kebler, Amer. Chem. Jour., 1895, xvii. 822 ; abst. J.C.S., Ixx. ii. 551. A. H. Allen, Analyst, xxi. 85. Page 403. The basicity of Quinine. D, & D. L. Howard, Pharm. Jour., 1898, i. 154. Page 408. The testing of Quinine Sulphate. M. Kubli, Chem. Centr. y 1895, ii. 1058 ; abst. J.C.S., Ixx. ii. 550 ; Ixxii. ii. 168. 0. Hesse, Arch, de Pharm., ccxxxiv. 195 ; abst. J.C.S., Ixx. ii. 550. Page 408. A test for the purity of Quinine Salts. J. de Vrij; abst. J.S.C.I., 1897, xvi. 165. Page 408. Tests for Quinine. T. G. "Worm ley, Amer. Jour. Pharm. ^ Ixvi. 561 ; abst. Pharm. Jour., xxv. 542. Page 418. Acid Quinine Hydrochloride (-B.P.,1898) contains B(HC1)2+3H20. Page 418. Interaction of Quinine Hydrochloride and Caffeine. Paul and C own ley, Pharm. Jour., 1900, i. 438. Page 419. Quinine Arsenate exists in the form of fine, colourless, silky needles. G u i g u e s obtained it by adding a dilute solution of arsenic acid to hydrated Quinine, suspending in water and gently warming until distinctly acid. The warm solution was then exactly neutralised with dilute ammonia, the liquid allowed to cool, and the salt crystallised. Page 419. Notes on Quinine Acetate. J. R. Hi 1 1, Pharm. Jour., 1900, i. 416. Page 419. Quinine Glycerophosphate. P r u n i e r, Jour, de Pharm. , xii. 272 ; abst. Pharm. Jour., 1900, ii. 439. Page 423. The Tincture and "Wine of Quinine (P.P., 1898) are prepared with quinine hydrochloride instead of with the sulphate. Page 424. Therapeutic value of Quinine Esters. v e r 1 a c h, Pharm. Zeit., xlvl. 694; abst. Pharm. Jour., 1901, ii. 449. Page 429. Action of Bromine on Cinchonidine. J. G a 1 i m a r d, Chem. Centr., Ixx. 401 ; abst. Pharm. Jour., 1901, i. 485. ADDENDA. 595 Page 431. Examination of commercial samples of Cinchonine. Jun g f 1 e i s ch and Leger, Compt. rend., cxxxii. 828 ; abst. J.S.C.L, 1901, xx. 499. Page 431. Action of sulphuric acid upon Cinchonine. Z. H. Skraup, abst. J". ^. a/., 1901, XX. 499. Page 431. Preparation of Allocinchonine. 0. J. Hlavnicka, abst. J.S.C.I.t 1901, XX. 499. Page 432. Assay of Liquid Extract of Cinchona. F. H. Alcock, Pharm. Jour., 1901, ii. 90 ; abst. Analyst, xxvi. 323. Page 445. Assay of Tincture of Cinchona. Farr and Wright, Pharm. Jour., xxiii. 248. Page 445. Valuation of Cinchona Extract. M. L. Hulsebosch, Chem. Centr., 1896, i. 141 ; abst. J.C.S., Ixx. ii. 682. Page 449. Determination of the Alkaloids in Cinchona Bark. M. L. Hulsebosch, Pharm. Centr. , xiv. 289 ; abst. J.S. C.I. , 1896, xv. 887. W.Haubensack, Pharm. Centr. , xxxii. 294 ; abst. J. ,S. C. /. , 1 892, xi. 779. J. H. Schmidt, Chem. Zeit., xvi. 307 ; abst. J.S.C.L, 1893, xii. 467. W. Lenz, Zeit. anal. Chem., xxxviii, 141; abst. J.S.C.L, 1899, xviii. 408. H. E kxo os, Arch. de. Pharm., 1898, p. 328 ; abst. Amer. Jour. Pharm. , April, 1 899. F. M y 1 1 e n a e r e, /. >S'. C. 7. , 1902, p. 721. Page 449. B. A. Yan Ketel suggests the following method of Cinchona- assay, which is applicable to all the fixed alkaloids soluble in ether. Four grammes of the powdered bark is mixed with two grammes of powdered lime, 5 c.c. of solution of ammonia added, and boiled on a water-bath under a reflux condenser for half-an-hour with 100 o.c. of ether. The solution is then filtered, the insoluble matter washed with 80 C.C. of ether, and the filtrate shaken well with 10 c.c. of 10 per cent, hydrochloric acid. The acid liquid is separated, and the ethereal solution well washed with water, which is added to the acid. The acid solution is then shaken with excess of caustic soda solution and ether. The extraction with ether is repeated, the ether evaporated, and the alkaloids weighed. The alkaloids left on evaporation may also be titrated. Page 461. Morphology and Pharmacognosy of Berberis vulgaris. G. Pinchbeck, Pharm. Joiir. , 1 901, i. 262. Page 461. Materia Medica oi Berberis. Pharm. Jour., 1901, ii. 402, Page 461. Determination of Berberine. H. M. G o r d i n, abst. Pharm. Jour., 1901, ii. 599. Page 464. Composition of Berberine Phosphate. F. S h e d d e n, PhoA'm. Jour., 1900, ii. 89. Page 467. Constitution of Hydrastine and its derivatives. Frits ch, Liebig's Annalen, cclxxxvi. 21 ; abst. Pharm. Jour., xxv. 1193. Page 467. Properties of the Alkaloids of Hydrastis Canadensis. K. v o n Bunge, Chem. Centr., 1895, i. 1173 ; abst. J.C.S., Ixx. ii. 492. Page 467. The Chemistry of Hydrastine and its salts. Freund and Dormeyer, Berichte, xxiv. 2730, 3164; abst. J.C.S., Ix. 1518; Ixii. i. 223. Page 467. Assay of Hydrastis. 0. Schreiber, abst. Pharm. Jour., 1901, ii. 273 ; Gordin ani Prescott, Jour. Amer. Chem. Soc, xxi. 732 ; abst. Phann. Jour., 1899, ii. 445 ; 1900, i. 8. 596 ADDENDA. Page 468. Reactions of Hydrastine and other alkaloids. D. V i t a 1 i, abst. J.C.S., Ixii. i. 755. Page 474. In Tea, the Cutfeine exists largely as a glucoside or in some other complex form. Page 475. According to Tasilly, Hydrated Caffeine does not part with all its combined water even when heated to 150° C, at which temperature the alkaloid begins to volatilise. Page 475. Loss of weight of Caffeine when heated. F. B. P o w e r, Fharm, Jour., 1900, ii. 148. Page 483. Caffeine Ethyl-iodide is obtained by heating caffeine with excess of ethyl-iodide in a sealed tube for twenty hours at a temperature of 160 ta 170° C. It is crystallised from alcohol. It melts at 182 to 183° C. , and is soluble in water and alcohol, but insoluble in ether, benzol, chloroform, petroleum-ether, and carbon disulphide. Page 483. Characters of Caffeine Citrate, B.P. F. B. P o w e r, Pharm. Jour.^ 1900, ii. 148. Page 489. Determination of Caffeine. E. Tassily, Ball. Soc. Chim.^ xvii. 596, 706, 761 ; abst. J.S.C.L, 1897, xvi. 697, 831. M. Gomberg, ATner. Chem. Jour., xviii. 331; abst. Analyst, 1896, xxi. 193. A. Delacour, J. Pharm. et Chim., iv. 490 ; abst. Analyst, 1897, xxii. 76. Page 489. Determination of Caffeine. Forst er and Reic hel m an n, and Hilger and Juckenack, Chem. Centr., 1897, [1], 775; abst. Analyst, 1897, xxii. 189,238. G.L. Spencer, Amer. Chem. Jour.,x\x. 279 ; sihst. J.C.S., Ix. 134, 964. C. C. Keller, Chem. Zeit., xxi. 102 ; abst. J.S.C.L, 1897, xvi. 568. W. A. Puckner, Avier. Chem. Jour. , xviii. 978 ; abst. J. S. C.I. , 1896, xv. 925. P e t i t and T e r r a t, Bttll. Soc. Chim.,lS96,-p. 811 ; Sihst. Analyst, 1896, p. 232. E.Georges, J. Pharm. et Chim., xvi. 58 ; abst. Analyst, 1896, xxi. 232. F. Vite, Chem. Centr., 1890, ii. 274; abst. J.G.S., Ix. 372. Trillich and Gockel, Zeit. f. IJntersuch., 1898, p. 101 ; abst. Analyst, 1898, xxiii. 179. Guillot, Apoth. Zeit., viii. 132; abst. J.C.S.,\yiiv. ii. 608. C. H. La Wall, Amer. Jour. Pharm., 1897, p. 350 ; abst. Analyst^ 1897, xxii. 238. Page 490. Determination of Caffeine in Tea. N. V. Sokoloff, abst. J.O.S., Ixiv. ii. 352. Ke liner, Forschungs-berichte, iv. 88; abst Pharm. Jour., 1897, ii. 83. Page 490. Determination of Caffeine in Tea. E. H. G a n e {Jour. Soc. Chem. Ind., 1896, page 95) states that, after a trial of several processes, he found the author's method to give the best and most concordant results. A comparison of the results obtained by Gane with the methods of Paul and C o w n 1 e y and of the author shows that the latter process gives identical or higher yields of caffeine than the former, whilst the alkaloid is obtained in a state of great purity. Gane regards the author's method as less tedious and more accurate than other methods. He prefers in every case to boil the tea with 600 c.c. of water in the first place, and to add the lead acetate before filtration. This modification is at least necessary in the case of "gunpowder " and certain other teas, as was pointed out by the a u t h o r (page 490), owing to the slow filtration of the liquid. ADDENDA. 597 Page 493. Theobromine crystallised from aqueous solutions may be dried without loss at a temperature of 50° C. The base is not hygroscopic, differing largely from Caffeine in this respect ; and, according to Th. Paul, its solubility in water at 18° C. is 1 in 3282. Page 493. The Examination of Theobromine. M. Francois, J. Pharm. et Ghim., vii. 521 ; abst. Analyst, 1898, xxiii. 213. Page 493. Theobromine and its homologues. B runner, and B runner and Leins, abst. J.S.C.L, 1898, xvii. 78, 946. Page 496. Determination and separation of the Alkaloids of Cocoa. Brunner and Leins, Chem. Centr., 1898, p. 512; abst. J.S.C.L^ 1898, xvii. 961. Page 496. Determination of Theobromine in Cocoa, etc. Hilger and Eminger, Forsch. Ber., 1894, p. 292; abst. J.C.S., Ixviii. 642. L. Maupy, J. Pharm. et Ghim., 1897, v. 329; abst. J.S.C.L, xvi. 641. P. Siiss, Zeit. anal. Chem., xxxii. 67; abst. J.C.S., Ixiv. 198. Page 496. W. E. Ku n ze (Zeit anal. Chem., xxxiii. 1 ; abst. Analyst, 1894, page 194) has proposed the following method for the determination and separation of the Alkaloids of Cocoa : — For the estimation of the total alkaloids, ten grammes of the cocoa is boiled for twenty minutes with about 150 c.c. of five per cent, sulphuric acid, filtered, and the residue thoroughly washed with boiling water. The alkaloids are precipitated from the filtrate by a large excess of a nitric acid solution of sodium phosphomolybdate, and the liquid kept warm for twenty- four hours. It is then filtered, the precipitate washed with the dilute sulphuric acid, and at once decomposed by baryta-water, the excess of barium being precipitated by passing carbon dioxide through the liquid. The liquid and precipitate are together evaporated to dryness, dried, and exhausted with boiling chloroform under a reflux condenser. On evapora- tion, the filtered chloroform solution leaves the alkaloids almost perfectly pure, and containing only a trace of ash. For the separation of the caffeine and theobromine thus obtained, the theobromine is converted into its insoluble silver salt. (Caffeine does not form a similar compound.) For this purpose, the mixed alkaloids are dis- solved in ammonia, a considerable excess of silver nitrate added, and the liquid boiled down to a very small bulk, and until all free ammonia is expelled. The crystalline precipitate of theobromine-silver salt (C7H7AgN402) is collected, well washed with boiling water, dried, ignited, and the residual silver weighed. If a known measure of standard silver nitrate be employed, the amount of theobromine precipitated may be deduced from the excess of silver contained in the filtrate as determined by V o 1 h a r d's method. After the titration, the alkaloids may be readily extracted from the precipitate and filtrate, and tested as to their purity, etc. Kunze's paper contains a valuable resum^ and criticism of the methods hitherto employed for the separation of the cocoa alkaloids, and the sub- stantial accuracy of his process is confirmed by analytical data. Page 499. Materia Medica of Tea. Pharm. Jour., 1901, ii. 661. Page 604. Percentage of Caffeine in Chinese Teas. J. K o c h s, abst. Pharm. Jov/r., 1900, ii. 637. 598 ADDENDA. Page 504. Analysis of Tea. Domergue and Nicolas, J. Pharm. et Chim., XXV. 302 ; abst. J.C.S., Ixii. ii. 926. Page 506. Detection of Extracted Tea. W. A. Tichomirow, abst. Ghem. News, Ixvii. 196. Page 509. New Adulterant of Tea. Delaite and Lonay, Bull. A, Beige Chim., xi. 13 ; abst. J.S.C.I., 1897, xvi. 700. Page 510. Mineral matter in Caper Tea. Analyst, 1899, xxiv. 333, Page 516. The analysis of China Teas. P. Dvorkovitz, abst. Jour. Soc, Chem. Ind., x. 276. Page 518. In employing Eder's process for the determination of Tannin in Tea, the excess of copper may be determined by ferrocyanide. Maltscheffsky, J. Pharm. CMm., xxil 270 ; abst J.C.S., Ix. 132. Page 520. The composition of Caper Tea. C. E s t c o u r t, Analyst, xxiv. 30. J. White, ibid., p. 117. Page 522. Chinese Tea and certain of its substitutes. E. Collin, Jou/r. de Pharm., xi. 15, 52 ; abst. Pharm. Jour., 1900, i. 91. Page 526. The composition of Mate or Paraguay Tea. H. K u n z-K r a u s e, Arch, de Pharm., ccxxxi. 613; abst, Pharm. Jour., xxiv. 442. Mc Ken d rick and Harris, Pharm. Jour., 1890, ii. 52. Page 526. Contributions to the study of Mate. P. Macquaire, J. Pharm. et CMm., 1896, p. 346 ; abst. Analyst, xxii. 18. B. A. Katz, Zeit. Nahr. Uhtersuch., x. 364 ; abst. Analyst, 1897, xxii. 41. Page 526. The word "mate" is used adjectively, referring to the gourd from which the scalding infusion is sucked through the bombilla— that is, a tube having a bulb at one end. We should, therefore, always say " Yerba Mate," the gourd-plant. Page 526. Materia Medica of Mate Tea. Pharm. Jour., 1901, ii. 661. Page 526. Mate Tea. W. F. Buist, Pharm. Jour., 1901, i. 155. Page 527. The composition of Oatha edulis. E. Collin, Pharm. Jour,, xxiv. 345. Page 527. The following analyses of " Coffee-Tea" (coffee leaves) are from the Lancet, 5th August, 1893 : — Whole Leaf. Small Broken Leaf. Caffeine, 2-66 3-20 Tannin, 7-14 6-66 Extract, 39-45 34-40 Moisture, 7-60 7-69 Ash, 6-10 5-50 Page 528. Proportion of various constituents of Coffee. Herfeldt and Stutzer, Zeit. angew. Chem., 1895, p. 469 ; abst. J.C.S. , Ixx. ii. 63. Page 528. Proportion of water in raw Coffee. B. Niederstadt, Forsch. Ber., 1897, p. 141 ; abst. Analyst, 1897, xxii. 322. Page 528. A new Alkaloid of Coffee (Cotfearine). Fors ter and Reich el- man n, Pharm. Zeit., xlii. 309 ; abst. Pharm Jour., 1897, ii. 84. P. Paladin o, abst. ATialyst, 1895, xx. 141. Page 528. Composition of Coffee from the Grand Comoro Island. G. Bert rand, Compt. rend., cxxxii. 162, 164; abst. Analyst, xxvi. 188. ADDENDA. 599 Page 528. Studies on new descriptions of Coffee. T. F. H a n a n s e k, abst. Analyst, xxiv. 284. Page 530. Alteration in composition of Coffee during roasting. H i 1 g e r and Juckenack, Forsch. Ber.,iy. 119; abst. Analyst, 1897, xxii. 287. H. Jaeckle, Zeit. f. Untersitch., 1898, p. 457; abst. Analyst, 1898, xxiii. 264. Page 533. The Carboliydrates of the Coffee-berry. E. E. E w e 1 1, Amer. Chem. Jour., xiv. 473 ; abst. J.S.C.L, 1893, xii. 614. Page 533. A Ptomaine in Coffee. S. Bein, Zeit. angew. Chem., 1898, p. 658 ; abst. Analyst, 1899, xxiv. 36. Page 534. Glazed Coflfee-berries. E. H a n a u s e k, abst. Analyst, xxiv. 36. Page 535. Exhausted Coffee-berries. P. E. Ham el Roos, ah^t. Analyst, xvi. 160. Page 535. Analysis of a spurious roasted Coffee. M. M alj ea n, /. Pharm,. et Chim., 1896, p. 352 ; abst. Analyst, 1897, xxii. 17. Page 535. E. Bertarelli calls attention to the adulteration of roasted coffee-beans by the practice of pouring over them a boiling aqueous solution of borax, whereby an increase of about 12 per cent, in their weight is produced, without their original hardness being impaired. Genuine roasted coffee does not usually contain more than about 3 per cent, of water. Borax should be looked for in cases where 4 per cent. or more of water is found. Page 536. Note on a sample of artificial Coffee-berries. C. H. C r i b b. Analyst, xxvii. 114. Page 538. Adulterations of Coffee. G. y^ ixtz, Zeit. f. Untersuch., 1898, p. 248 ; abst. Analyst, xxiii. 209. Pear main and Moor, Analyst, XX. 176. Page 538. Variations in the composition of Chicory. B. Dyer, Analyst, xxiii. 226. Page 538. Sugar in roasted Chicory. E. G. Clayton, Analyst, xx. 12. Page 538. Composition and Analysis of Chicory. J. Wolff, abst. Analyst^ 1899, xxiv. 261. Page 539. Determination of Caramel in Coffee roasted with sugar. Fresenius and G r ii n h u t, Zeit. anal. Chem. , xxxvi. 225 ; abst. Analyst, 1897, xxii. 285. Page 539. The analysis of Chicory. A. Ru f f i n, Chem. Ccntr., 1898, p. 1147 j abst. J.S.C.L, 1898, xvii. 699. Page 544. Composition of Dandelion root (Taraxacum). L. E. Sayre» Amer. Jour. Pharm., Ixix. 543 ; abst. Analyst, xxiii. 10. Page 545. Composition of the Ash of Coffee. F. W. Dafert, abst. J.C.S., Ixvi. ii. -207. Page 547. Composition of ' ' coffee-palace " Coffee Infusions. E. G. Clayton, Analyst, xxii. 172. Page 553. Composition and Analysis of Coffee Extracts. Moor and Priest, Analyst, 1899, xxiv. 281. Page 554. Composition of Kola-nuts. Uffelmann and Bomer, Zeit. angew. Chem., xxiii. 710; abst. Analyst, 1895, xx. 42. Knox and Prescott, Amor. Chem. Jour.,xx. 34 ; abst. Analyst, 1897, xxii. 131. E. K neb el, Apoth. Zeit.. vii. 112; abst. J.S.C.L, 1892, xi. 545. 600 ADDENDA. . K. Dieter icli, Apoth. Zeit., xi. 810 ; abst.V.^.C.7., 1897, xvi. 160. P. Carles, J. Pharm. et Chim., xvi. 104 ; Ann. der Chimie, xviii. 345 ; abst. Analyst, 1896, xxi. 265, 292. Page 554. False Kola-nuts. J. H. Hart, Pharm. Jour., 1898, i. 184. Page 554. Kolanin and Coconin, the Glucosides of the Kola-nut. C. Schweitzer, Pharm. Zeit, xliii. 380, 389; abst. Pharm. Jour.y 1898, ii. 50. Page 554. Assay of Kola Nut and its Fluid Extract. O. S c h u m m, Apoth. Zeit.,1%^%, p. 682 ; abst. J.S.O.L, 1899, xviii. 408. J. W arin, J. S.G.I. , 1902, p. 645. Page 554. Materia Medica of Kola-seeds. Pharm. Jour., 1901, ii. 638. E. M. Holmes, Pharm. Jour., 1900, i. 665. Page 556, Determination of the chief constituents of Cocoa Beans. H. Beckurts, Arch, de Pharm., ccxxxi. 687 ; abst. J.C. S., Ixvi. ii. 363. Page 559. The starch of Cocoa. E. S. B a s t i u, Amer. Jour. Pharm., Ixvi. :369 ; abst. Pharm. Jour., xxv, 173. Pages 561 and 566. Sugar in commercial Cocoas. M. Schroder, Zeit. angew. Chem., 1892, p. 173 ; abst. J.C.S., Ixiv. 100. Pages 561 and 566. Sugar in Chocolate. X. Rocqnes, Ann. der Chimie, 1896, p. 288 ; abst. Analyst, 1896, xxi. 256. P. Carles, J. Pharm.et Chim., viii. 245 ; abst. J.S.C.I., 1898, xvii. 1076. H. Pellet, Bull. A. Beige Chim., xiv. 790 ; abst. J.S.C.L, 1897, xvi. 474. Page 561. Detection of Arachis Nuts in Chocolate. A. B i 1 1 e r y s t, Bull. A. Beige Chim., x. 447 ; abst. Analyst, 1897, xxii. 215. Page 562. Detection of Gelatin in Chocolate. P. Onfroy, J. Pharm. et Chim., 1898, p. 7 ; abst. Analyst, 1898, xxiii. 265. Page 563. Analyses of commercial Cocoas. J. S. Liv ersed ge, P^arm. Jour., xxiii. 922. F. Yaple, Amer. Jour. Pharm., 1895, p. 318. Page 564. Determination of " soluble " constituents in Cocoa. A. S t u t z e r> Zeit. angew. Chem., 1892, p. 510 ; abst. J.S.C.L, 1893, xii. 54. Page 567. Detection of added Starch in Cocoa. G. Possetto, Pharm. Cenir., xxxix. 152 ; abst. Pharm. Jour., 1898, i. 525. Page 568. Detection of Sesame Oil in Chocolate. G. Possetto, Chem. Centr., 1901, ii. 236 ; abst. J.C.S., Ixxx. ii. 703. PRINTED BY NEILL AND CO., LTD., EDINBURGH. UNIVERSITY OF CALIFORNIA MEDICAL CENTER LIBRARY THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW Books not returned on time are snbject to a fine of 60c per volume after the third day overdue, increasing to $1.00 per volume after the sixth day. Books not in de- mand may be renewed if application is made before expi- ration of loan period. QD271 A42 Allen, A.H, 66348 ir. --%^^\r— ^'^ V^^/,^_ Sfp^ /94^