ee FR ZRPBRLER NT ERENTO Er BE N ee - on r PRPRFRIRBLELTER ee ER a PFEH: NT nei sereerchein, 3 wis BEREREE ee ana ee Dunn un ne ed nn nam rennen net, Di nn a a a “ D BE, BE ’ u nee sr r 3 x 5 . Er me ERTEEOTTHEE PR ne aan anna 0 aan nee ana de leer ers Mer Sun en nm nennen genen Benanana vennngrrranungrahe an nl Med K13632 . PEANT ANALYSIS: QUALITATIVE AND QUANTITATIVE. BY G. DRAGENDORFF, Pr.D., PROFESSOR OF PHARMACY IN THE UNIVERSITY OF DORPAT, RUSSIA. Translated from the German BY HENRY G. GREBNISH, FLC LONDON : ESITLEIERE, TINDALL, AND GOX., 20, KING WILLIAM STREET, STRAND. 1884. [All Rights Reserved.) Me WELLCOME INSTITUTE LIBRARY TRANSLATOR’S PREFACE. Soon after the publication in German of Professor Dragendorff’s ‘ Pflanzenanalyse,’ it was suggested to me that an English transla- tion of the work would supply a want keenly felt by both English chemists and English pharmaeists. A thorough knowledge of the German language and a practical acquaintance with many of the processes described, gained whilst a pupil in the author’s laboratory, would, it was thought, enable me to offer a translation of trustworthy accuracy ; and this has been my endeavour. Such alterations or additions as have been considered needful have been made in the text, the proof-sheets of which have been submitted to the author. Most of the references have been checked, as accuracy in this particular was deemed very important. To many of them, how- ever, access could not easily be had ; but it is hoped that even in these cases very few will be found to be incorrect. To secure to English readers the usefulness of the numerous quotations, refer- ence has been frequently made, in brackets, to abstracts or trans- lations that have appeared in English journals. One word has been employed in a somewhat unusual sense. The solution obtained by treating a substance with spirit is called a “tineture,’ with cold water an “infusion,’ and so on. All such solutions have been included in the general term ‘extract > the latter will not, therefore, necessarily mean the dry residue com- monly called ‘extraect.’ The name ‘ petroleum spirit ’ sufficiently indicates the origin of iv TRANSLATORS PREFACE. the liquid. A petroleum spirit boiling above 60° C. should not be used. Benzene should boil at 80-81° ©. (‘Die gerichtlich- chemische Ermittelung von Giften,’ Dragendorff, 1876.) The index will be found more copious than in the original ; it has been compiled from the English text. The high reputation of the author and the favourable reception accorded to his ‘ Pflanzenanalyse ’ are a sufficient guarantee for the value of the work. THE TRANSLATOR. LoxDon, October 1st, 1883. AUTHOR’S PREFACE. WHILST engaged in collecting the material for my ‘ Ermittelung von Giften,’ I formed the intention of utilizing the knowledge then acquired of the alkaloidal and other constituents of plants to improve and extend the present methods of plant analysis. In accordance with this intention I subsequently discussed in my ‘Chemische Werthbestimmung’ the detection and estimation of the active prineiples of some powerful drugs, and at the same time promised further communications on allied substances. In the meantime, I gradually became convinced of the need of devising a process of analysis that should include as many as possible of the more important constituents of plants. Such a process was, I thought, a desideratum, as I had frequently ob- served that the methods of examination published in some of my researches were adopted by other chemists in cases in which I myself should have deviated from them. This consideration was mainly instrumental in indueing me to carry my plan into execution more rapidly than was originally contemplated. No one can be more thoroughly aware than I am myself of the insuffliciency of the material at present available for the construction of a systematic process of analysis, nor can any- one be more conscious of the necessity for sifting and improving the contents of the following chapters. I may, however, be per- mitted to remark that in proposing to my pupils subjects for scientific investigation, I have never lost sight of the plan I had . formed, and I have been able to benefit by the results of upwards vi AUTHORS PREFACE. of one hundred dissertations or communications published by myself or by my scholars. Comparatively few chemists will have learnt, as I have done, that nothing can tend so much to the end aimed at as increased activity in this much-neglected branch of chemistry ; and it was the hope of stimulating young chemists to steady, persevering _ work in testing the methods now placed before them, and devis- ing better ones, that finally decided me. I doubt the possibility of making, without assistance, such progress as I think necessary ; and I trust, therefore, that the publication of this little work will be followed by an increase in the number of my fellow-workers. As will be explained in the introduction, I have endeavoured to construct a method that shall comprise at once both the qualita- tive and the quantitative, micro- as well as macro-chemical analysis of plants and their constituents. All widely distributed vegetable substances are to be included, the detection of rarer ones facilitated, and the method so arranged that other principles not hitherto observed shall, if present, attract the attention of the investigator. An exhaustive treatise on all the known constituents of plants would naturally have obscured the method of examination. This result I have endeavoured to avoid by compressing the method of examination proper (Part I.) into the smallest possible limits ; and by following it up with further observations (Part II.) on the characters, etc., of the substances there mentioned. Numerous notes and a systematic, as well as alphabetical, index will guard the reader from confusion. I have been compelled to restriet myself to the treatment of the more important constituents of plants, that is, those that are of importance to the plant itself, or that play an important part in its economical application. The extracts in which rarer or less important substances are to be looked for have been pointed out, but it has been left for the reader himself to gain further information about them from other sources. Numerous refer- ences will aid him in his search, and also direct his attention to a number of analyses that may be of service to him in modifying or extending the process here recommended. AUTHORS PREFACE. en I have assumed in my readers an acquaintance with the leading prineiples of general and analytical chemistry, and have, there- fore, passed over parts of the latter, such as ultimate and ash- analysis, since these have been fully treated of elsewhere. Sub- jects that have been discussed at length in my ‘ Ermittelung von Giften,’ and ‘Chemische Werthbestimmung starkwirkender Droguen,’ have been referred to as briefly as possible. An ulti- mate analysis is, of course, frequently necessary in order to demonstrate the identity of a substance isolated during the investigation with some other known body. Ihave, therefore, col- lected analyses of the constituents of plants, and have arranged them both alphabetically and according to the percentage of carbon they contain. THE AUTHOR. SYSTEMATIC INDEX. INTRODUCTION . e ; £ - $1. General Remarks, p. T —$2 Objeot of the Work ; Division of Matter, p. 2.—$ 3. eye Principles in the Analysis of Plants, p. 3 METHOD OF EXAMINATION FOR THE MORE IMPORTANT CONSTITUENTS OF PLANTS a . I. PRELIMINARY OPERATIONS. ESTIMATION OF MOISTURE AND > Asır . $ 4. Drying the Materials, p. 5.—$ 5. Treatment of Fresh Plants, $ 6. Pulverization, p. 6.—$ 7. Estimation of Ash, p. 7 II. ExAMINATION OF THE SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT ; ETHEREAL AND FIxED OILs, WAx, ETC. $ 8. Value of Petroleum Sn in the rn: en leur) p. 8.— $ 9. Methods of Extraction, p. 8.—$ 10. Treatment of Fresh Aromatic Vegetable ee p. 10 EXAMINATION OF THE FIXED OIL $ 11. Macroscopical and Microscopical Deren: Total Esti- mation, p. 10.—$ 12. Composition, Qualitative; Oleic and Linoleic Acids, p. 11.—$. 13. Quantitative ; Estimation of Gly- cerine, p. 12.—$ 14. Cetyl-, Cerotyl-, Melyl- Alcohol, p. 13.— $ 15. Volatile Fat-Acids, p. 13.—$ 16. Non-volatile Fat- Acids; Separation, p. 14.-—$ 17. Determination of Melting- Point, p. 14.—$ 18. Melting-Points of the more important Fat- Acids and Mixtures of thesame, p. 15.—$ 19. Further Remarks on Oleic, Ricinoleic Acid, ete., p. 18. CHLOROPHYLL AND ALKALOIDS EXTRACTED SIMULTANEOUSLY WITH THE FIXED OIL $ 20. Optical Properties and Dee e Ohlörophyil) » or $ 21. Influence of Fixed Oil in Determining the Solution of Alkaloids, p. 20. ExXAMINATION OF THE ETHEREAL OIL . $ 22. Detection and Estimation, p. 21.—$ 23. Hennaikon: in the Presence of Fixed Oiland Resin, p. 22.—$ 24. Distillation of Larger Quantities of Ethereal Oil, p. 23.—$ 25. Examination of the Aqueous Distillate for Volatile Acids, Formic, Acetic, Acrylie, Toxicodendrie, Salicylous Acid, p. 23.—$ 26. Salicylie, Benzoic, Cinnamie Acid, Styracin, Cinnamein and Aldehydes of above Acids, p. 24.—$ 27. Physical Properties of Ethereal Oils; Umbelliferone, p. 25.—8 28. Reactions, p. 26.—$ 29. Ethereal Oils containing Nitrogen and Sulphur, p. 26.—$ 30. Constituents of Ethereal Oils, p. 27.—$ 31. Hydrocarbons and Oxygenated Constituents, Stearoptenes, p. 28.—$ 32. Other PAGE or 10 19 21 SESTEMATIC INDEX. Constituents, p. 28.—$ 33. Aldehydes, p. 29.—$ 34. Volatile PAGE — nu _ Acids, p. 29.—$ 35. Ethereal Salts and the Alecohols contained inthem ; Primary, Secondary, and Tertiary Aleohols, p. 29. III. ExauisAatıon OF THE SUBSTANCES SOLUBLE IN ETHER : RESINS AND THEIR ÄALLIES 3 sl $ 36. Methods of Extraction ; Fixed Oil, p. 31. —$ 37. Chlorophril, p. 32.—8$ 38. Portion of the Ethereal Extract Soluble in Water ; Hamatoxylin, Gallie Acid, Glucosides, Alkaloids, etc., p. 32.— $ 39. Portion Soluble in Alcohol, p. 33.—8 40. Microchemical Examination ; Treatment of the Substances dissolved by Ether with various Solvents; Crystallization, etc., p. 33.—$ 41. Behaviour of Resin to Aqueous and Alcoholic Potash, Sulphurie Acid, Nitrie Acid, Bromine, etc., p. 34.—$ 42. Action of fused Potash, Resorein, Phloroglucin, Pyrogallol, Protocatechuic and Paroxybenzoic Acids, p. 34.—$ 43. Dry Distillation of Resin ; Umbelliferone, Pyrocatechin, p. 36.—$ 44. Examination of that Part of the Ethereal Extract dissolved by Alcohol; Psonio- fluoresein, Chrysophanice Acid, etc., p. 36.—$ 45. Acids pro- duced by the Action of Alkalies on Anhydrides ; Santonin, etc., p- 36.—$ 46. Direct Extraction with Ether, p. 36. IV. EXAMINATION OF THE SUBSTANCES SOLUBLE IN ABSOLUTE ALCOHOL ; Resıns, TAnNINs, BITTER PRINCIPLES, ALKALOIDS, GLUCOSES, ETC. 38 $ 47. Methods of Extraction ; Estimation of Total Substances dis- solved, p. 38.—$ 48. Estimation of the Portion Soluble in Water ; Phlobaphenes, Alkaloids, etc., p. 38. EXAMINATION OF TANNIN ; 39 $ 49. Detection, p. 39.—8 50. Detection Sonnen, p- 39, —$ El. Reactions of most Tannins ; Microchemical Detection; Alcohol more suitable for their Fistwetion than Water, p. 40.—8$ 52. Methods for their Estimation : I. Acetate of Lead, p. 41; II. Acetate of Copper, p. 42; III. Stannous Chloride, p. 42 ; IV. Tartar Emetic, p. 42; V. Acetate of Zinc, p. 43; VI. Ferric Acetate, p. 43 ; VII. Permanganate of Potassium, p. 43; VIII. Chlorinated Lime, Iodic Acid, Iodine, p. 45; IX. Caustic Potash and Atmospherie Air, p. 45; X. Cinchonine, p. 45 ; XI. Hide, p. 46; XII. Gelatine, p. 46.—$ 53. Tannic and Gallic Acid, p. 47 EXAMINATION FOR GLUCOSIDES, ALKALOIDS, ETC. . 48 $54. Bythe Method of Agitation, p. 48.—855. List of Bitter Dih- ciples, Acids, ete, removable from Acid Solution by Agitation with Petroleum Steit, Benzene, Chloroform, p. 49.—$ 56. Ex- traction of Alkaloids from Ammoniacal Solution, p. 49.—8$ 57. Direct Test for Glucosides, Alkaloids, ete., p. 50.—$ 58. Isola- tion and Purification of Substances not removable by Agitation; Separation from Glucose, ete., p. 51.—$ 59. Separation of cer-. tain Glucosides and Bitter Principles from Tannin, etc., p. 52. —8 60. Decomposition of Compounds of Lead with Bitter Principles, etc., p. 52.8 61. Detection of the Glucosidal Nature of a Substance, p. 53.—8 62. Other Reactions of Gluco- sides, p. 54.—$ 63. Alkaloids In Isolated by the Method of Agitation ; Group-reagents; Lassaigne’s Nitrogen Test, p. 55. —$ 64. Isolation by Precipitation with Potassio-mercuric Iodide, etc., p. 57.—$ 65. Estimation, p. 58.—$ 66. Estimation SYSTEMATIC INDEX. of Theine, p. 62.—$ 67. Estimation of Total Alkaloids in Cinchona, p. 62.—$ 68. Acidimetrie Estimation, p. 63.—$ 69. Separation of Alkaloids from one another, p. 63.—$ 70. Glu- coses Soluble in Alcohol, p. 64. V. EXAMINATION OF SUBSTANCES SOLUBLE IN WATER : MUCILAGE, SAPONIN, ACIDS, GLUCOSES, SACCHAROSES, ETC. ; $ 71. Method of Extraction, p. 65.—$ 72. Estimation of Total Sub- stances Dissolved, p. 69. EXAMINATION FOR VEGETABLE MUCILAGE, DEXTRIN, LEYVULIN, TRITICIN ; SINISTRIN . . $ 73. Detection and Estimation of Mncilage, p- 65. —$ 74. Wiege: table Albumin and Tarsoates Present in Mucilage-preeipitate, p-. 66.—$ 75. Inulin, p. 66.—$ 76. Dextrin, en Sinistrin, Triticin ; Estimation, p. 67. SAPONIN AND ITS ALLIES ; ' } F . $ 77. Separation from Dextrin, a p. 67.—$ 78. Estimation, p- 68.—$ 79. Digitonin, p. 69. EXAMINATION FOR AcıDs . $ 80. Precipitation with Acetate RN: ft p- 69. —$ 81. Male, Fumaric, Oxalic, Racemic, Citrie, Aconitic, Tartarice Acid ; Marattin, p. 70.—$ 82. Volumetric Estimation of the Fre going Acids. Free and Combined Acid. Mineral Acids, p. 71. EXAMINATION FOR GLUCOSES, SACCHAROSES, ETC. $ 83. Volumetrie Estimation of Glucose with Fehling’s inlon: = Gravimetrie Estimation with Copper, p. 72.—$ 84. Knapp’s Method; Sachsse’s Method, etec., p. 73.—$ 85. Influence of Sac- charoses, p. 75.—$ 86. Estimation of Saccharose in presence of Glucose, p. 75.—$ 87. Estimation of Saccharose alone; Inver- sion, p. 75.—$ 88. Distinguishing Tests for Saccharose and Glucose, p. 76.—$ 89. Distincetive Characteristics of the Various Saccharoses and Glucoses ; Purification, p. 76.—$ 90. Soluble Modification of Arabic Acid ; Albuminous Substances not precipitated by Alcohol, p. 76.—$ 91. Mannite and its Allies, Bx 77. EXxAMINATION FOR ALBUMINOIDS SOLUBLE IN WATER, AMMONIA, AMIDES, NITRIG AcıD D. 5 P & : $ 92. Detection and Estimation ; Microchemical Detection ; Pro- toplasm, Cell-nucleus, Crystalloids, p. 78.—$ 93. Estimation of Legumin, Globulin, and Allied Substances, p. 79.—$ 94. Vege- table Albumin, p. 79.—$ 95. Estimation of Total Albuminoids Soluble in Water; (a) By Precipitation with Tannin, p. 80.— $ 96. (5) From the Nitrogen, p. 80.—$ 97. Estimation of Am- monia, p. 81.—$ 98. Amido-compounds, p. 82.—$ 99. Estimation of Nitrie Acid (a) by Schulze’s Method, p. 83.—$ 100. (b) By Wulfert-Schloessing’s Method, p. 85.—$ 101. Selerotic and Cathartie Acid, etc., p. 86. EXAMINATION FOR InuLıN $ 102. Characteristic Properties R Innlle, and Intel, e“ 86. VI. ExAMINATION OF THE SUBSTANCES SOLUBLE IN DILUTE SoDA : METARABIC AcID, ALBUMINOIDS, PHLOBAPHENE, ETC, $ 103. Method of erachten, p- 88.—8 104. Detection and Klima. tion of Albumen, p. 88.—$ 105. Estimation, p. 88.—$ 106. Nitrogenous Substances not dissolved by Dilute Soda, p. 89.— PAGE r vd 67 69 78 86 88 xü SYSTEMATIC INDEX. PAGE $ 107. Mucilaginous and Albuminous Substances, Phlobaphene, ete., not Precipitated by Acids, p. 89.—$ 108. Phlobaphene, Polyporic Acid, Humus, ete., p. 90. VII. ExaminaTIon OF SUBSTANCES SOLUBLE IN DILUTE HYDROCHLORIC Acıp; STARCH, PARARABIN, OXALATE OF CALCIUM, ETC. 97 $ 109. Extraction, p. 91.—$ 110. Estimation of Oxalate of Calcium, p- 31.—$ 111. Estimation of Oxalate of Caleium and Pararabin, p- 92.—$ 112. Estimation of Pararabin, p. 93.—$ 113. Estima- tion of Oxalate of Caleium and Starch, p. 93.—$ 114. Estima- tion of Oxalate of Calcium, Starch, and Pararabin, p. 93.— $ 115. Estimation of Starch, p. 93. VIII. EstımATion OF LIGNIN AND ITS ALLIES, AND OF OÜELLULOSE . 95 $ 116. Lignin, Incrusting and Cuticular Substances, Suberin, p- 95.—8 117. Estimation of Cellulose, p. 96. CONCLUDING REMARKS 97 $ 118. Remarks on the Method of an ee p- 97.—8 119. On the Object of Plant Analysis, p. 97. SPECIAL METHODS ; SUPPLEMENTARY NOTES, ETC. o0 FATS AND THEIR CONSTITUENTS, CHOLESTERIN, FILICIN, ETC. ) $ 120. Estimation of Fat in General; Apparatus for Extrac- tion, p. 99.—$ 121. Resinification, p. 101.—$ 122. Elaidin-test, p- 101.—8 123. Behaviour to Sulphuric Acid, p. 102.—8 124. Behaviour to other Reagents, p. 102.—$ 125. Detection and - Estimation of Free Fat Acids contaminating Fixed Oils, p. 105.—$ 126. Detection and Estimation of Cholesterin, Phytosterin, Filicin, Kosin, Euphorbon, Laetucon, Lactucerin, Echicerin, Cynanchocerin, Helenin, Coumarin, Melilotie Acid, Styrol, Myroxocarpin, Diosmin, Kämpferid, Asaron, Angelicin, Anemonol, Capsicin, Capsaicin, Amyrin, Bryoidin, p. 106.— $ 127. Caoutchouc, p. 109.—$ 128. Estimation of Glycerine, p. 109.—$ 129. Cetyl-, Cerotyl-, Melyl-alcohol ; Cerotene ; Vegetable Wax ; Microchemical Detection of Wax, p. 110. 8 130. Estimation of Oleic Acid, Linoleic Acid, Laurie Acid ; Separation of the latter from Oleice and Myristic Acid; of Oleice from Stearie Acid, p. 111.—$ 131. Separation of Fat- acids from Resin-acids, p. 112. CHLOROPHYLL AND ITS ALLIES ; AS $ 132. Remarks on the Chemistry of Ohloröpkyiil ” 113.— $ 133. Possibility of Estimating, p. 115.—$ 134. Erythrophyll and Chlorophyllan, ete., p. 115.—$ 135. Xanthophyll, Hypo- chlorin, Etiolin, Anthoxanthin, p. 116. ETHEREAL OILS, VOLATILE AcIDS, ETC. ; 117 $ 136. Examples of Estimation, p. 117.—$ 137. Estimation wich Bisulphide of Carbon, p. 118.—$ 138. Mixtures of Fixed and Ethereal Oils, Resin, ete., p. 118.—$ 139. Volatile Acids: Angelic, Methylerotonie, Capric, Caprylic, (CEnanthie, Cap- roic, Valerianic, Butyric, Propionie, Acetic, Formic Acids and their Separation, p. 119.—$ 140. Identification of Volatile Acids by Saturating Power, ete., p. 120.—$ 141. Optical Tests for Ethereal Oils, Solubility, p. 120.—$ 142. Colour-reactions of Ethereal Oils, p. 121.—$ 143. Fractional Distillation, p. 124. —$ 144. Examples of Analyses, p. 125. A ee. SYSTEMATIC INDEA. xii PAGE ReEsıss, ANTHRAQUINONE-DERIVATIVES, GALLIC Acıp, BITTER Prıx- CIPLES, ETC. $ 145. Coniferous Resin- Aeide; } Podocarpie Acid, Phy Ilie ‚Keid, Mongumie Acid, Pxonia acid, Chrysin, etc. ; More important Methods of Isolating Resin-Acids, p. 127.—$ 146. More im- portant Commercial Resins; Estimation of Ethereal Oil, Mucilage, ete., p. 129.—$ 147. Pzxonio- fluorescin, p. 131.— $ 148. Anthraquinone-derivatives, Chrysophanie Acid, Chry- on Emodin, Frangulic Acid, Alizarin, Purpurin, Scler- erythrin, Ruberythric NL Rhinacanthin, Alkannin, Bixin, Curcumin, ete., p. 131.—$ 149. Recognition of Anthraquinone- derivatives, p. 136.—$ 150. Haematoxylin, Brasillin, Santalin, p. 136.—$ 151. Gallic Acid, Catechin, Pyrocatechin ; Detection, Estimation, ete., p. 137.—$ 152. Quereitrin, Quercetin, Thujin, Rutin, Robinin, Luteolin, Gentisin, Constituents of Podophyllin, p. 138.—$ 153. Jalapin and Allied Resin-glucosides ; Con- volvulin, Tampiein, Turpethin, ete., p. 140.—$ 154. Santonin ; Estimation, p. 141.—$ 155. Picrotoxin, Digitalin, Digitoxin, Digitalein, Digitonin, Digitin, Coriamyrtin, Ericolin, Vanillin (Estimation), Ostruthiin, Peucedanin, Oreoselon, Athamanthin, Laserpitin, Cubebin, Betulin, Anacardie Acid, Cardol, p. 142. $ 156. Other Bitter Principles Soluble in Ether ; Absinthiin, Hlaterin, Hop-Bitters, Meconin, Meconie Acid, Methystiein, Quassiin, etc, p. 146. —$ 157. Lichen Acids and their Allies: Roccellic, Lecanoric, Orsellinie, Gyrophoric, Parellie, Patellaric, Evernice, Everninic, Usnic, Carbusnic, Vulpic, Erythric, Beta-erythric, Cetraric, Lichenostearie, Stictic, Lobaric, Atranorie Acid; Ceratophyllin, Pieroerythrin, Picrolichenin, Variolinin, Zeorin, Sordidin, Calyein, etc., p. 149.—$ 158. Orcin and Betaorein ; Estimation of Orein, p. 152. TANNINS > 152 s 159. So p. 152. ig 160. rede Nas or er Decomposition-products, Phlobaphene, etc, p. 153.—$ 161. Proneness to Decomposition, p. 154.—$ 162. Preparation in a State of Purity, p. 155.—$ 163. Tannic Acids sparingly Soluble in Water: Tannins of Alder and Hops, p. 156.—$ 164. Occur- rence of two different Tannins in the same Plant, p. 156.— $165. Notes on the more important Tannins ; Tannic Acids from Catechu, Rhatany, Kino, Tormentilla, Bistort, Horse- chestnut, Sumach, Myrobalans, Divi-divi, Bablah fruits, Pome- granate, Tea, Coffee, Oak, Willow, Elm, Fir, Birch, Acacia, Male-fern, Cinchona, Cinchona-nova, Ipecacuanha, Mate and Celastrus; Morin-tannic, Gallo-tannic, Leditannic and Nuci- tannic Acid, p. 156. OTHER GLUCOSIDES . 163 $166. Cyelopin, Phrrenikkin, p- 163. 8167. Selability; Dean of the more important Glucosides. Amygdalin and Lauro- cerasin, Estimation; Myronie Acid, Estimation ; Sinalbin (and Sulphocyanate of Sinapine), Menyanthin, Pinipierin, Coniferin, Arbutin, Daphnin, Saliein, Populin, Benzohelicin, Philyrin, Phlorrhizin, AEsculin, Fraxin, Syringin, Globularin, Pittosporin, Samaderin, Colocynthin, Bryonin, Ononin, Apiin, Datisein, Physalin, Dulcamarin, Hesperidin, Crocin, Glyeyr- 127 xiv SYSTEMATIC INDEX. rhizin, Panaquillon, Thevetin, Chamelirin, Gratiolin, Paridin, Convallarin, Convallamarin, Helleborin and Helleborein, Scillain, Saponin, Digitonin, Senegin, Melanthin, Parillin, Sapogenin, etc., Indican, Indigo-blue, p. 164.—$ 168. Non- glucosidal Bitter Principles, Cusparin, Chinovin, Cniein, p. 175. —$ 169. Aloins, p. 176.—$ 170. Carthamin, p. 178. AÄLKALOIDS - 5 A N { . a $ 171. Colour Reactions of the more important Alkaloids, p. 178.—$ 172. Identification, p. 181.—$ 173. Double Chlorides with Gold and Platinum, p. 181.—$ 174. Further Remarks on Titration with Potassio-mercuric Iodide ; Atropine, Hyos- cyamine, Coniine, Strychnine and Brucine, Morphine, Narco- tine, Chelidonine, Veratrine, Sabadilline and Sabatrine, Calabarine and Physostigmine, p. 182.—$ 175. Estimation of Coniine with Phosphomolybdie Acid; of Pilocarpine; Ap- plication of Phosphotungstie Acid, Tannie Acid, Picrie Acid in the Estimation of Alkaloids, p. 184.—$ 176. Determination of Alkaloid in Tea, Coffee, Guarana ; Lieventhal’s and Claus’s Methods, p. 186.—$ 177. Estimation of Theobromine in Cacao; Methods of Trojanowsky and Wolfram, p. 187.—8$ 178. Esti- mation of Piperine, p. 188.—$ 179. Volumetrie Estimation of Nicotine, p. 188.—$ 180. Estimation of Coniine, p. 189.— - $ 181. Separation of two or more Alkaloids from one another ; Jervine and Veratroidine, Paricine, Narceine and Narcotine, Morphine and Codeine, Morphine and Narcotine, Strychnine and Brucine, p. 189.—$ 182. Separation by Solvents; Strych- nine and Brucine ; Colchieine and Colchiceine ; Cinchonine and Amorphous Alkaloid; Delphinine and Delphinoidine ; Morphine and Narcotine ; Morphine, Codeine, and Thebaine ; Delphinine, Delphinoidine and Staphisagrine, p. 191.—$ 183. Separation of Quinine and Cinchonidine from other Cinchona Alkaloids; of Quinidine from Cinchonine ; of Quinine from Cinchonidine ; of Strychnine from Brucine: of Calabarine from Physostigmine ; of Chelidonine from Sanguinarine ; of Muscarine from Amanitine ; Paytine, etc., p. 195.—$ 184. Sepa- ration of the more important Cinchona Alkaloids from one another, p. 194.—$ 185. Estimation of Cinchona-Alkaloids by Polarization, p. 198.—$ 186. Rarer Cinchona-Alkaloids ; Ari- cine, Cusconine, Quinamine ; Paricine, Paytine, p. 198.—8 187, Estimation of the more important Opium-Alkaloids, p. 199. —$ 188. Methods of Procter, Prollius, Flückiger, p. 200.— 8 189. Other Alkaloids ; Ergotinine and Picrosclerotine ; Cura- rine, Erythrophleine, Lobeliine, Conessine, or Wrightiine, Har- maline and Harmine, Surinamine, Aribine, Atherospermine, Rhoadine, Violine, Beberine, Belladonnine, Cocaine and Hygrine, Chlorogenine and Porphyrine, Corydaline, Cytisine, Ditamine, Geissospermine, Aspidospermine, Dulcamarine, Glaucine, Fumarine, ete., p. 201.—$ 190. Amanitine, Musca- rine, Choline, Betaine, p. 205.—$ 191. Asparagine, Glutamine and Estimation of the same, p. 206.—$ 192. Leucine, Chenopo- dine, Tyrosine, Rhatanhin, p. 207. VEGETABLE MUCILAGE 3 . x x ; R 8 193. Differences in Gum and Pectin, p. 208.—$ 194. Modified PAGE SYSTEMATIC INDEX. xV PAGE Method of Examination for Gum, p. 209.—$ 195. Characters of Soluble Vegetable Mucilage (Arabin, Arabic or Gummic Acid); Metarabic Acid, p. 210.—$ 196. Behaviour to Re- agents ; Commercial Varieties of Gum-arabic, p. 211.—$ 197. Separation of Arabin from Dextrin, Glucose, Saccharose, etc., p. 212. DEXTRIN, TRITICIN,. LEVULIN, ETC. . & j 5 . 212 $ 198. Distinetive Characters, p. 212.—$ 199. Formation of Alcoholates ; Composition ; Estimation by Titration and Polarization, p. 213. GLUCOSES i e 214 $ 200. Detection of Grape-sugar; Reactions to distinguish Grape-sugar from Cane-sugar, Milk-sugar, Mannite, etc., p. 214.—$ 201. Detection and Estimation in Presence of Dextrin, p. 215.—$ 202. Detection of Dextrin in Presence of Cane-sugar, p. 215.—$ 203. Estimation of Glucoses in Presence of Cane-sugar, p. 215.—$ 204. By Fermentation ; Influence of Substances retarding Fermentation,p. 216.—$ 205. Characteris- tic Properties of Grape-, Fruit-, Invert-, Saliein-, and Caragheen- sugar ; Phlorose, Arabinose, Galactose, p. 217.—$ 206. Inosite Sorbin, Eucalyn, Nueite, p. 219.—8 207. Cane and Milk-sugar ; Maltose, Melitose, Melezitose, Mycose, p. 220.—$ 208. Estima- tion of Glucoses and Saccharoses by Polarization, p. 221.— $ 209. Estimation of Two Glucoses by Titration and Polariza- tion, p. 222.—$ 210. Estimation of Cane- and Invert-sugar, p. 223.—$ 211. Estimation of Three Sugars in Solution to- gether, p. 224.—$ 212. Mannite, Dulcite (Melampyrite), Isodul- cite (Rhamnodulcite), Hesperidin-sugar, Sorbite, p. 224.— $ 213. Mannitan, Quercite, Pinite, Abietite, p. 225. Acıns N . - . ' ß h . 214 $ 214. Reactions of Malic Acid; Separation from Oxalic, Tartaric, Citrice, Succinic, Gallic, Tanniec, Benzoic, Acetic, Formie Acid, p. 214.—$ 215. Estimation of Citrie Acid as Barium-salt, p. 206.—$ 216. Reactions of Citrie Acid ; Aconitie Acid, p. 227.—$ 217. Estimation of Tartaric Acid as Acid Tartrate of Potassium, p. 223.—8$ 218. Estimation of Tartaric and Citrie Acid when present together ; Separation from Malic, Oxalic, Phosphoric, and Sulphuric Acid ; Racemie Acid, p. 228.—$ 219. Oxalic Acid; Separation from Tartaric and Citrie Acid ; Isolation from Oxalate of Calcium, p. 230.— 8 220. Suceinic Acid; Separation from Oxalic, Tartaric, and Citrie Acid, p. 230.—8 221. Fumaric and Maleie Acids; Kinie Acid; Rubichloric Acid, p. 232.—$ 222. Lactice Acid, p. 232.—8 233. Glycolic Acid, p. 233. AÄLBUMINOIDS, ETC. . . e ; 5 ; . 234 8 224. Calculation of Nitrogen into Albuminoids, p. 234.—8 225. Repetition of Estimation of Legumin, p. 234.—$ 226. Casein, Gluütencasein, Fibrin ; Globulin, p. 235.—$ 227. Vitellin, p. 236.—$ 228. Myosin, p. 236.—$ 229. Estimation of Albumin- oids by Titration with Tannin, p. 236.—$ 230. Comparison of Results with those of the Estimation by Coagulation ; Fer- ments; Diastase, Invertin, Emulsin, Myrosin, Papayotin, ete., p- 237.—$ 231. Estimation of Albuminoids with Acetate of xvi SISTEMATIC INDEX. Copper, p. 238.—$ 232. With Acetate of Lead, p. 238.—$ 233. Estimation of Albuminoids Soluble in Dilute Acid ; Albumin- oids capable of being assimilated, p. 240.—$ 234. Albuminoids Soluble in Spirit ; Glutenfibrin, Gliadin, Mucedin, p. 241.— $ 235. Properties of the same, p. 242.—$ 236. Gluten ; Estima- tion, p. 243.—$ 237. Albuminoids precipitated simultaneously with Metarabic Acid, etc., p. 243.—$ 238. Nitrogenous Sub- stances Insoluble in Water, Dilute Acid, and Dilute Alkali, p. 244. ANMINE COMPOUNDS $ 239. Distinctive Charaoters of Me Diaminss, Ei Ben? 244. $ 240. Separation of Ethyl- and Methyl-amine from the cor- responding Di- and Tri-amines, p. 244.—$ 241. Approximate Estimation of Amides, p. 245.—$ 242. Cathartic Acid, Selerotic Acid, Scleromuein, Assay of Rhubarb, p. 247. STARCH, LICHENIN, WOOD-GUM, ETC. . $ 243. Constituents of Starch, p. 249.—$ 244. Ode of de Cell-wall that turn Blue with Iodine ; Lichen-starch, p. 250.— $ 245. Lichenin and Gelose, p. 251. Be 246. Wood-gum, p. 252. CELLULOSE, LIGNIN, AND ALLIED SUBSTANCES $ 247. Researches of Fremy and Terreil on ne of een tissue ; Cuticular and Incrusting Substances ; Modifications of Cellulose, Lignin (Vasculose, Tnerusting Substances), Suberin, Glyco-lignose, Glyco-drupose, p. 252.—$ 248. Composition of Cellulose, p. 256.—$ 249. Properties of the Various Forms of Cellulose, p. 256.—8 250. Crude Fibre ; Estimation, p. 257. PERCENTAGE COMPOSITION OF THE CONSTITUENTS OF PLANTS REFERRED TO COMPOSITION OF THE MORE IMPORTANT CON STITUEN TS OF PLANTS ARRANGED ACCORDING TO THE PER- CENTAGE OF CARBON . j N . ALPHABETICAL INDEX PAGE 244 249 252 PLANT ANALYSIS: BOUALITATIVE AND. QUANTITATIVE INTRODUCTION. $ 1. An accurate qualitative and quantitative analysis of a plant or vegetable substance is not unfrequently referred to as one of the most diffieult tasks that a chemist may be called upon to undertake. Attention is very properly direeted to the great number of species of plants that occur in nature, to the great abundance and variety of their chemical constituents, and to the circumstance that almost every skilful analysis of a plant that has not previously been examined yields new, hitherto unknown products. Prominence’is also justly given to the fact that the analysis of vegetable substances differs from that of minerals, inasmuch as the elements present in the latter have in many instances only to be separated and weighed or measured, either as such or in the form of certain of their simpler, more easily recognisable compounds, whilst in the analysis of plants it far more frequently occurs that the proximate principles themselves must be first separated before they can be examined or weighed. These reasons are all admissible ; we are, moreover, justified in pointing out, amongst other numerous difheulties encountered in the analysis of plants, the great proneness to decomposition of many of the constituents of vegetable substances and the errors that may arise therefrom, not only in the estimation of these bodies themselves, but also of such substances as may accompany them. But surely these considerations should not tend to pre- vent investigations from being carried out which are equally important for scientific botany and chemistry, for medieine, phar- macy, dieteties, agriculture, ete. By systematically arranging 1° 2 | 8 1,2. INTRODUCTION. the methods of examination hitherto devised, either for the estimation of a single constituent or for the separation of several substances contained in a plant, I hoped to succeed in inducing others to conduct investigations in a department of chemistry at present so much neglected ; and it was in that hope that I decided upon the compilation of this work. In it I trust to be able to show that for the separate estimation of many substances we have methods at our disposal which, in point of accuracy, are nearly abreast of the processes employed for the determination of mineral constituents, and that we can often obtain results really serviceable in the investigation of the more important component substances contained in a plant. I especially hope to succeed in showing that analyses of plants possess in one respect an advantage over the analyses of minerals, inasmuch as it often happens, in examining mixtures or conglomerates of several chemical individuals, that in the latter case a much less satisfactory insight into the constitu- tion can be obtained than in the former. The elements, for instance, of which a granite is composed can easily be deter- mined by inorganic analysis, but it is exceedingly difficult to ascertain with exactitude in what quantity each separate mineral occurring in the granite is present. But in the analysis of vegetable substances the endeavour is made from the outset to separate the different chemical individuals from one another, and by the use of various solvents this is fre- quently possible. In this respect, therefore, the analysis of a plant can often be made more complete than that of a mineral. $ 2. The object that I have sought to attain in this work was the compilation of a method of analysis applicable to the qualitative and quantitative examination of vegetable substances of both known and unknown composition, and of an introduc- tion to the qualitative and quantitative determination of the various more important constituents of plants with which we are at present acquainted. I need scarcely observe that I have given the fullest possible consideration to the question as to which tissues of the plant contain the various constituents, and have therefore, for that purpose, made use of mierochemical analysis. With reference to the arrangement of the matter in the work, I would remark that in the method of analysis contained in ss 2, 3. INTRODUCTION. 3 Part L, I have not separated the qualitative and the quantita- tive determinations of the more important substances from each other. I have made the method of separation serve as a leading principle, and have therefore grouped together the constituents of plants in such a manner that all those may be considered together that are isolated by the same means. I have then placed in sub-divisions of the principal groups such substances as may be isolated by special methods, and these latter are also discussed. The more important peculiarities of the various bodies belong- ing to the different groups, as well as special methods for the estimation of some of them, have been placed in Part II, which has been so arranged as to follow closely on Part I. in the form of a supplement. In this way I hope to be more easily able to avoid repetition, and especially to facilitate investigations in which the substances that may be found are unknown. Thus a method of analysis, taking account of the more important con- stituents of plants, may be traced through the work. $ 3. It has always been accepted, as an important principle, by those who have been engaged in plant analysis, that the constituents present should be separated as far as possible by means of different solvents. I have also followed this plan, which has in many instances proved itself adapted to the attain- ment of the object in view, and I concur with those chemists who recommend the use, as far as practicable, of the most in- different solvents. If, in the analyses of vegetable substances I have already made, I have deviated from the course followed by my predecessors,! I have done so, first, in increasing the number of solvents; and secondly, in varying the order in which those solvents were allowed to act upon the substances under examination. I shall subsequently show that this may have a great influence on the result of the analysis. !I draw particular attention here to Rochleder’s ‘Anleitung zur Analyse von Pflanzen und Pflanzentheilen’ (Würzburg, 1858), which I regard as open- ing up new ground in this subject. See also Wittstein, ‘Anleitung zur chemischen Analyse von Pflanzentheilen’ (Nördlingen, 1868), and an English translation of the same by Baron von Mueller, ‘ The Organic Constituents of Plants and Vegetable Substances and their Chemical Analysis’ (Melbourne, 1878); Arata, “Guja Paralel Anälysis immediato de los Vejetales’ (Buenos u a and a paper by Parsons in the American Chemical Journal, ol. i. No, 6. 1—2 4 | 83. INTRODUCTION. It will be seen from the foregoing that the principal groups into which I have divided the matter to be treated are formed by the behaviour of the plant constituents to solvents. In a chapter preceding the method of examination proper, I have given a few general rules for plant analysis. METHOD OF ANALYSIS FOR THE MORE IMPORTANT CONSTITUENTS OF PLANTS. PRELIMINARY ÖOPERATIONS. ESTIMATION OF MOISTURE AND ASH. $4. Drying.—In the majority of cases the parts of plants at our disposal for analysis have already been dried, and we can only take -account of the small amount of moisture that has been absorbed from the air in consequence of the hygroscopie nature of the vegetable tissue in contact with it. I can only recommend that the estimation of moisture, for which a temperature not - exceeding 110° will as a rule suflice, be made with a small quantity of the substance. I should not advise the drying of the material intended for use in the investigations to be discussed in the following chapters, because, even at a temperature of 100° to 110°, a number of constituents prone to decomposition undergo chemical change. It will be sufficient if the moisture be estimated in about 2 to 5 grams, that is, if that quantity be kept at the tem- perature indicated till it ceases to lose weight. By means of this determination the results of all other estimations can be calculated to the dry substance.! 1 An apparatus for drying material for agrieultural (chemical) analysis has been described by Hugo Schulz (Landw. Versuchsstat, vol. ix. p. 213) ; one for the rapid estimation of water in organic substances by Gawalovski in the Zeitschrift f. anal. Chemie, xiii. 267 (1874). For the determination of moisture in fruits rich in sugar, such as apples, etc., Tschaplowitz (ibid. Jg. 19, p- 243, 1880), recommends the slices to be first extracted with absolute alcohol containing 10 to 20 per cent. of ether, and then dried at 100° to 110°, the ether-alcohol solution to be evaporated, the residue heated to 85° to 90° and then added to the dry substance. See also Reischauer in the Jahresb. f. Pharm. Jg. 1867, p. 8 (Amer. Journ. Pharm, xxxviii, 74); Schoonbroodt, 6 PRELIMINARY OPERATIONS. That portion which has served for the determination of the moisture can subsequently be used for the estimation of the total ash. $ 5. Treatment of Fresh Plants.—I£ fresh plants or parts of the same are to be examined it will be advisable in many cases, at least if a quantitative examination is to be made, to first dry the material, or it will at any rate be necessary for those portions which are subsequently to be treated with petroleum spirit, ether, alcohol, and similar menstrua. Here, too, it will be desirable to make an accurate estimation of the moisture, and in doing so it is advisable to allow the temperature to rise very gradually to 100° or 110°, The greater part of the material can as a rule be dried at a temperature under 30° till in a condition suitable for powder- ing, and the amount of moisture still retained in it can be deter- mined in a small portion by a separate estimation. In drying fleshy fruits or roots care should be taken not to reduce them to too fine a state of division. Leaves which are not too fleshy do not require any preparation at all. It is very desirable that as little of the cell-tissue as possible should be deprived of its natural covering, as by doing so the action of the air on the decomposable constituents is only facilitated. With substances which are very rich in sugar it is better not to dry the portions destined for the estimation of the saccharine matter at all, but to examine them in the fresh state. The same holds good for such substances as are very rich in ethereal oil, or contain volatile acrid compounds ; I shall subsequently show that such compounds may be easily isolated from, and determined in, the fresh plants. Of course the amount of such volatile substances as may be found by other means must be deducted from the result of the determination of moisture. 86. Powdering.—It is of the greatest importance that the material for the various estimations should be uniformly mixed and reduced to the very finest powder possible It may be’ asserted that the greatest errors made in the analysis of plants are due to the material not having been reduced to a sufficiently fine state of subdivision. Estimations of oil made with ether or petroleum spirit often show differences of several units per cent., ibid. Jg. 1869, p. 9. (Pharm. Journ. Trans. [2], xi. 84). In the latter work illustrations are given of the difference in composition that may be met with in fresh and dried, and in quickly and slowly dried, vegetable substances. 87. ESTIMATION OF ASAH. 7 because these solvents do not penetrate into the cells, but only dissolve that which is adhering to the external surfaces of the object. It must be admitted that it is often very diflicult to reduce a vegetable substance to an impalpable powder, but the necessity of sparing no trouble in this respect must be most strongly urged. It may sometimes be expedient to dry very hard substances, such as seeds, ete., at 100° to 110° before powder- ing them. Coffee-seeds may thus be reduced to quite a fine powder, especially if triturated in an agate mortar with a known quantity of powdered glass or sharp sand (that has been pre- “ viously treated with hydrochloric acid). Somewhat hard sub- stances may occasionally be grated upon a fine grater with advantage, and then powdered as above. Tough material, too, and such as is to be examined in the fresh state, may be generally prepared in this way. In working with substances containing much fixed oil it is sometimes expedient to dry the residue after the first extraction with petroleum spirit, ete., powder it again and repeat the extraction. $ 7. Estimation of Ash.—With regard to the total ash, which is usually estimated in plant analysis, reference may be made in the majority of cases to the generally known methods of procedure. For vegetable substances that are very difficult to incinerate, it is advisable, after carbonization, to cool, powder as finely as possible, and continue the heating, placing a cylindrical tube vertically above the platinum dish, so as to create a current of air. Or the incineration may be conducted in a Hempel’s jacket with access of air. If easily fusible salts are present and prevent complete incineration, the admixture of about an equal weight of nitrate of ammonium with the cooled mass, and repeated ignition, may render good service. Or the carbonized mass may be mixed with a weighed quantity of oxide of iron, and the incineration continued.! After weighing the ash the quantity of carbonic acid present in it is to be determined and deducted from the total weight. The carbonic acid is simply a part of the organic matter, the rest of which has been burnt off, and is to be determined in other ways. It is also desirable to test the ash for sand, and finally, if a complete analysis is not required, to estimate at least the total quantity of phosphorie and sulphuric acid and potash. (See also $ 82). ! Compare also Bornträger, Zeitschr, f. anal. Chemie, B. xvii. p. 440 (1378). S SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. IL EXAMINATION OF THE SUBSTANCES SOLUBLE IN PETROLEUM | SPIRIT. j ETHEREAL AND FATTY OILS, WAX, EIC. $ 8. Petroleum Spirit.—I have proposed the use of petroleum spirit in the analysis of plants on account of its being a relatively good solvent for most ethereal and fatty oils, but not for the majority of resins and allied substances which would have been simultaneously brought into solution had ether been .used. We have therefore in this liquid a means of more accurately estimating ethereal and fatty oils than was formerly possible with ether. Another advantage which petroleum spirit possesses over ether is that it does not, like ether, cause a coagula- tion of soluble albuminous compounds in substances rich in such bodies. As it is desirable to deprive the material of fat before extracting the soluble albuminous substances for their quantitative determination, the whole or part of the residue after treatment with petroleum spirit may be very well employed for this purpose. A chief condition for the successful application of petroleum spirit is that it be very volatile. It must therefore be purified by repeated fractional distillation, and care taken that it contains no compound boiling above 45°. It is, moreover, desirable to distil it over fat (lard) to free it from some of the impurities of more powerful odour. $ 9. Extraction with Petroleum Spirit.—It has already been men- tioned in $ 6 that vegetable substances to be extracted with petroleum spirit must be reduced to the finest powder possible. ft is advisable in such extractions to employ a known quantity of petroleum spirit—say five to ten times that of the substance to be treated ; or, better still, for every gram of the latter 10 ce. of the former. A small narrow eylinder with glass stopper may 89, EXTRACTION. 9 be used for this purpose. It should be weighed immediately after the introduetion of substance and menstruum ; or, if graduated, the volume only occupied by both need be noted. They may be macerated for about eight days, shaking several times daily, and then made up to the original volume or weight by the addition of petroleum spirit, to replace any that may have been lost by evaporation. This having been done, it is sometimes only neces- sary to evaporate an aliqguot part of the solution, and caleulate from the residue the weight of the substances which have been brought into solution.! The supernatant liquid frequently becomes so perfectly clear on standing, that all trouble of filtration may be avoided by removing with a pipette a definite volume, which may then be evaporated and weighed.? This method of procedure is especially to be recommended if the object under examination contains ethereal oil, in which case all washing of the residue, or any dilution whatever of the petroleum- spirit solution, should be carefully avoided. The more concen- trated the petroleum-spirit extract is, the more aceurate will be the gravimetric estimation of the ethereal oil. If, however, the petroleum-spirit solution is to be filtered off and the residue on the filter washed, care should be taken that a funnel with ground edges be employed and kept well covered. For the evaporation of the petroleum-spirit solution no porce- lain basin or round-bottomed platinum or glass dish should be used, on account of the loss easily caused by the capillarity of its sides. It is expedient, as a rule, to use a flat-bottomed glass dish with vertical sides and well-ground edges, a ground-glass plate acting as acover. If the presence of a rapidly resinifying oil is suspected, the petroleum-spirit solution may be evaporated in a tared flask by passing a current of carbonic acid gas through it whilst kept surrounded with warm water. (See also $ 138.) ! In this case, a slight error is introduced into the calculation, by the in- creased volume of the petroleum spirit due to dissolved oil. But this will, as a rıle, be so small that it may be entirely neglected ; or, if desirable, a correc- tion may be made after weighing the residual oil, since we know that the specific gravity of the fatty oils hitherto examined ranges from 091 to 0'925. ® Even when the petroleum-spirit solution does not become quite clear on standing, as is often the case when seeds are under examination, it is better to measure off a quantity with a pipette, filter it, and wash the filter and the mouth of the funnel (on the outside) with petroleum spirit, than to filter off the whole of the liquid and measure off a quantity for evaporation. 10 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. Shallow evaporating dishes, which can be enclosed between clamped glasses and weighed, may also be used if ethereal oil is present; but they must be placed in other larger dishes during the evaporation of the petroleum spirit. It is, however, preferable even in these cases to use the glass dishes with vertical sides pre- viously described. $ 10. Treatment of Fresh Plants. —Fresh, very aromatic parts of plants may be examined as stated in $ 5, without being previously dried.! "They should be as finely divided as possible by pressure and trituration, then packed in a small percolator, and the moisture present displaced by the smallest possible quantity of petroleum spirit or ether ; the latter is, perhaps, in this case to be preferred. The menstruum itself must subsequently be displaced by water. The liquids may be received in a graduated burette fitted with a glass stop-cock and long fine point ; in this the ether or petroleum spirit may be allowed to separate, and an aliquot part measured off for evaporation. (See also $ 22 and following.) EXAMINATION OF THE FIXED OlIL. $ 11. Detection and Estimation.—We will first consider the simpler case in which the petroleum spirit (or ether) dissolves fixed but not ethereal oil. The absence of the latter may be recog- nised by the light colour of the petroleum-spirit solution and its residue after evaporation, and by the absence of any aromatic odour which would otherwise be given off during the evaporation of the last traces of solvent, the operation being conducted at the ordinary temperature. That we really have a fixed oil to deal with may be shown by the uniform character of the spot left on evaporating a drop of the petroleum-spirit solution on a sheet of blue notepaper. On examining vegetable substances under the microscope, fixed oil is seen in the form of small globules of high refracting power, which dissolve in petroleum spirit, ether, and bisulphide of earbon, and are saponified by a dilute solution of soda. If the objects examined are fresh it is advisable to treat the section with a relatively large quantity of water. Concentrated solutions of sugar and similar substances have the power of dissolving oil, which is, however, again separated on the addition of a large i For information concerning the so-called dietheralysis, see Legrip, Union Pharm. V, vi. p. 65 (1876). u Zn ee zu Ep N VE 8 11, 12. DETECTION, ETC. OF FIXED OIL. 1l quantity of water. I do not think it improbable that in the juice of fresh plants oil is held in solution by cearbohydrates and does not show itself until separated by dilution with water. And in examining the expressed juice of fresh plants, or concentrated infusions of the same, it is well to bear this peculiarity of oils in mind. To determine the Zofal amount of fixed oil, the residue from the evaporation of part or all of the petroleum-spirit solution is dried at 100° till the weight remains constant, which may then be noted. For further information respecting the estimation of fixed oils, and especially the apparatus to be used, see $ 120. Compare also $ 36. The fatty residue so obtained may be kept for some time, to observe whether partial or complete solidification does not . gradually take place The solubility in absolute alcohol, spirit of 95 and 90 per cent., may also be tested, to ascertain whether free fatty acids, cholesterin, resinous bodies, caoutchouc, or such compounds, can be isolated. (Of. $$ 125, 126, 127, 130.) It may also be observed whether the oil is easy or diffieult to saponify, whether the soap is soft or hard, colourless or coloured, whether glycerine is separated during saponification, and the fat con- sequently contain glycerides (cf. $ 13), and whether the oil resinifies readily on exposure to the air ($ 121). Finally, the melting and solidifying points may be taken. Concerning this determination see $ 17. $ 12. Composition —If a further insight into the composition of the fixed oil is required, larger quantities must be prepared either by extraction, or by expression followed by extraction, accord- ing to the nature of the material and the quantity of oil it contains. A few qualitative experiments may first be made with a portion of this oil. If it remains fluid at ordinary temperatures the action of nitrous acid may be tried. The solidifieation of the oil would prove the presence of oleie ($$ ne 130) or an allied acid capable of conversion into elaidin ($ 12 In this case, on mixing the oil with about one-fifth of its alas of concentrated sulphurie acid, but little heat will be evolved, whilst compounds of the drying linoleic acid ($ 130) and its allies generally cause a considerable rise in temperature ($ 123). For comparison parallel experiments may be made with linseed and almond or 12 SUBSTANCES SOLUBLE .IN PETROLEUM SPIRIT. olive oil. Any colouration produced by the first drops of sul- phuric acid should be noted, and the experiment repeated with a small quantity of the oil, adding a little syrupy phosphoriec acid. The behaviour of the oil to syrupy chloride of antimony, nitrie acid (from 4 to 1 volume) of specific gravity 1'3, alone or com- bined with a little powdered sugar, may be tested. The action of concentrated solution of bisulphide of caleium, borax, and chloride of lime may also yield reactions characteristic of certain oils. (See $ 124.) It may finally be ascertained whether the oil combines quickly with oxide of lead, and whether the plaster so produced is soft or hard, soluble or insoluble in ether. If the fatty oil is solid at ordinary temperatures, a portion ' may be melted, and the above tests with acids, ete., applied. The solubility in ether should be tried, and note taken whether a solution in two parts of warm ether deposit solid matter on cooling. If the fixed oil from a vegetable substance partially solidifies after standing several days, the liquid part may be separated from the solid by filtration and expression, and each treated separately. $ 13. Composition ; Estimation of G@lycerine—It is well known that natural fats are almost imvariably mixtures of different glycerides or ethereal salts. If the various constituents of which a fixed oil is composed are to be ascertained, larger quantities (250 to 500 or 1000 grams) must be saponified with a solution of caustic soda of speeifie gravity 1'25 to 1'3; and after complete saponification, as shown by the soap dissolving in water warmed on the steam bath without the separation of undecomposed oil, the soap so formed may be thrown out by the addition of a con- centrated solution of salt. The separation may be performed with advantage in tall beakers, which should be placed on the water- bath until the soap has assumed such a condition that on cooling it can be removed as a solid cake. (See also $ 15.) A measured portion of the aqueous liquid, after the removal of the soap, may be concentrated on the water-bath, or preferably at a temperature of 70° to 80°, and the residue treated with absolute alcohol, or better with a mixture of about three volumes of absolute alcohol to one to two of ether, which dissolves the glycerine liberated by the decomposition of the oil. On evaporat- ing this solution the glycerine remains behind as a sweet syrupy $8 14, 15. CETYL, CEROTYL-, MELYL- ALCOHOL. 13 liquid. Itis optically inactive, and yields acrolein when heated with acid sulphate of potassium. If the soap, after removal from the liquid, is washed several times with solution of salt and the wash- ings added to the liquid in the beaker, then the glycerine obtained as described may be weighed. The estimation is not free from error, but it permits of an approximately correct idea being formed of the quantity of glycerine contained in the fat. (See $ 128.) $ 14. Cetyl-, Cerotyl-, Melyl- Alcohol.—In solid fats, especially in the so-called vegetable wax, cetyl, cerotyl, or melyl may be present as bases instead of glyceryl, in which case the fat is much more diffieult to saponify than it otherwise would have been and there is formed, in addition to the soap, a kind of alcoholate of the fat- alcohol. If to such a mixture of soap and alcoholate solution of chloride of barium is added, a barium soap insoluble in alcohol ‚ and ether is generally precipitated, whilst cetyl-, cerotyl-, or melyl- alcohol is liberated and may be extracted with ether. Or the precipitation may be accomplished with acetate of lead (in the absence of oleic acid), and the wax-alcohol extracted by ether from the dried mass. (Cf. $$ 126, 129.) The melting-point (see ‘$ 17) and the ultimate analysis will show which of these alcohols has been isolated ($ 129). Vegetable wax frequently dissolves in boiling absolute alcohol, but separates out again on the addition of a little water, as a rule before the resins ($ 145). $ 15. Volatile Fat-Acids.—In prosecuting the examination of the fat-acids the soap obtained in $ 13 is warmed and again decomposed with excess of hydrochlorie acid, the mixture of fat-acids separated from the aqueous liquid, and washed repeatedly with water. If the odour of the mixture points to the presence of a volatile acid, this latter must be separated from the less volatile by distillation. The distillate should be saturated with soda, evaporated, the residue again decomposed with hydrochlorie acid, and the fatty acids separated from the aqueous liquid. The possible presence of valerianie, caproic, caprylie, pelargonie, capric, and laurie ($ 130), also angelic and methyl-erotonie acid must be borne in mind. They may be identified by their boiling-points, saturating power for bases, and composition. Of course the acid must be tested to ascertain if it is a mixture or not of several volatile acids separable by fractional distillation. (Cf. $ 25.) 14 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT, 8 16. Less-volatile Fat-Acids. —lU no volatile acids are present, or after their separation by distillation, as direeted in $ 15, the less volatile fat-acids may be dissolved in alcohol and subjected in alcoholice solution to a fractional precipitation with acetate of magnesium. This salt precipitates members of the fat-acid series more easily than it does oleic acid and its homologues, and of the fat-acids proper of the C,H,,O, series, those standing highest in the series (i.e. containing the largest number of carbon-atoms) are precipitated first. The magnesium precipitates appear at first as soon as the acetate has been added, and in that case, after having been well shaken for some time, they may soon be filtered off. But subsequently it becomes necessary to add strong solution of ammonia, as well as the magnesium salt, to produce precipitation, and to allow the mixture to stand twelve to twenty- four hours in a cold place before filtering. The fractional preci- pitation is so contrived that each preeipitate shall weigh about 1 to 5 grams, and this is continued till the tolerably strongly am- moniacal liquid yields no further preeipitation on the addition of alcoholic solution of acetate of magnesium. Each preeipitate must be well washed with alcohol and decomposed with hydro- chloric acid. The fat-acid must be washed with water, dried, and crystallized once from boiling alcohol. After carefully drying the crystals the melting-point of each fraction must be taken. The acids are then recrystallized repeatedly from alcohol, and the melting-point again determined. (Üf. 88 130 to 131.) 8 17. Determination of Melting-Point—The following is the method I adopt when I have only a small quantity of the substance at my disposal. I place a minute portion on the surface of mercury contained in a small beaker. This is then introduced into a small eylindrical copper air-oven in such a way that it does not rest on the bottom, but remains three or four centimeters from it. To allow of careful observation of the substance during the experiment, I use as a cover for the air- oven an ordinary bottle the bottom of which has been cut off. A cork, perforated for a thermometer, is then fitted into the neck. The thermometer is now introduced through the perfora- tion into the mercury contained in the beaker placed just beneath, until the bulb is completely covered. In doing so it is desirable that some of the minute fragments of fat-acid, or other substance, be as near the bulb as possible. The whole is now heated over 818. MELTING-POINTS OF FAT-ACIDS. 15 a small flame, so that the temperature rises about 1° every two minutes. ! $ 18. Melting-Points of Fat-Acids.—The melting-points of the several fractions before and after purification are noted. If in the same fraction the same melting-point is observed on both oceasions, or if the estimations show a difference of only 0'5°, the conclusion may be drawn with tolerable safety that the preeipitate under examination contains only one fat-acid. The observed melting-point is then compared with those of the more important fat-acids, and the result arrived at confirmed, if possible, by ultimate analysis. Experiments that have hitherto been made assign to capric acid a melting-point of 300°; lauric, 43°6°; myristic, 53'8°; palmitie, 620°; stearic, 692°; arachie, 757°. Mixtures of two of these acids in certain proportions possess, as the investigations of Heintz? have shown, a lower melting-point than either of the constituents. Heintz has also noticed that the mixture, on solidifying, erystallizes in a characteristic form, or remains amorphous, according to the proportion in which the two constituents are present. Mixture of Stearic Acid. Palmitic Acid. Meltsat Solidifies at Manner of Solidification. 100 0 69:2° _ Crystalline scales. 90 10 67:2° 62:5° Ss 5 80 20 653° 603° Delicate crystalline needles. 70 30 62:9° 59.3° r = Br 60 40 60:3° 56°5° Amorphous, lumpy. 50 50 566° 550° Large crystalline lamellse. 40 60 56:3° 545° R ii x 30 70 551° 54:0° Amorphous, wavy, dull. 20 80 575° 538° Very indistinct needles. 10 90 601° 545° Fine erystalline needles. 0 100 62:0° — Crystalline scales. Mixture of Palmitic Acid. Myristic Acid.? 100 0 62:0° _ Crystalline scales. 90 10 60-1? 557° ri & 80 20 58:0° 53-5° Scalyand indistinct needles. 1 For further information about this determination see also Pohl, in Polyt. Centrbl. Jg. 1855, p. 165; Bergmann, in Kunst und Gewerbebl. f, Bayern. Jg. 1867, Januarheft; Buis, in Annalen d. Chem. und Pharm. xliv. pr 10255 Wimmel, in Annal. der Physik. xxxiii. 121 (Am. Journ. Pharm. xli. 22, 430) ; Redwood, in Pharm. Journ. and Trans. [3], vi. 1009 (1876). 2 Annal der Physik. xcii. p. 588 (Pharm. Journ. and Trans. [1], xv. 425) ; ef. ibid. Ixxxiv. 226. ® For particulars of the examination of a fat in which stearie, palmitic, and myristic acids were found, see Greenish in Pharm. Journ. and Trans. [3], x. 909. 16 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. Mixture of Palmitie Acid. Myristie Acid. 0 30 60 40 50 50 40 60 30 709 20 80 10 90 0 100 Mixture of Myristic Acid. Laurie Acid. 100 0 90 10 80 20 70 30 60 40 50 50 40 60 30 70 20 80 10 90 0 100 Mixture of Stearic Acid. Myristie Acid. 100 0 90 10 80 20 70 30 60 40 50 « 50 40 60 30 70 20 80 10 90 0 100 Mixture of Palmitic Acid. Laurie Acid. 100 0 90 10 89 20 79 30 60 40 50 50 40 60 30 79 20 80 10 90 0 100 Mixture of Stearie Acid. Laurie Acid. 100 0 90 10 80 20 Melts at Solidifies at 54:9° 51:5° 478° 47:0° 462° 49:5° 518° 53:8° 53'8° 51'8° 49'6° 467° 430° 374° 367° 35'1° 38°5° 41'3° 436° Melts at 69:2° Ya Be 65°0° 628° Manner of Solidification. 51'3° Extremely fine needles. 49:5° Amorphous, lumpy. 453° Large erystalline lamelle. 437° Indistinct lamelle. 48:7° „ >? 41:3° Amorphous. 453° Long needles. — Crystalline scales. .— Crystalline scales. 473° „ ” 44:5° Very minute crystals. 39:0> „ „ 390° Amorphous. 357° Large crystalline lamell®. 33'5° Amorphous. 323° Amorphous, frond-like. 33°0° EL) ” „ 36°0° Crystalline needles. — Scaly erystals. Manner of Solidification. Scaly crystals. Distinct erystalline scales. Rather less distinct erystalline scales. Still less distinet erystalline scales ; no needles or lamell. Scaly crystallization commences; no trace of needles or lamell«. Amorphous, opaque. Beautiful large erystalline lamelle. Crystalline lamelle. Indistinctly erystalline. Amorphous, opaque. Crystalline scales. Crystalline scales. Still distinct erystalline scales. Somewhat less distinet eryst. scales. Still less distinct erystalline scales. Granular, indistinct erystalline scales. Almost amorphous, opaque. Beautiful large erystalline lamelle. Small crystalline lamelle, Indistinctly erystalline, Amorphous,. Crystalline scales. Crystalline scales. Still distinct crystalline scales. „ ” ” 818. MELTING POINTS OF FAT ACIDS. 17 Mixture of Stearic Acid. Laurie Acid. Melts at Manner of Solidification. 79 30 62°0° Distinctly granular and scaly. 60 40 590° Granular; commencement of scaly erystallization. 50 50 55°8° Almost amorphous, slightly granular. 40 60 508° Amorphous, warty. 30 0 43:4° On the surface shining faces of small erystals. 20 80 38°5° Amorphous, warty. 10 90 41'5° Amorphous. 0 100 436° Crystalline scales. Heintz also noticed that a mixture of three fat-acids could melt at a still lower temperature, even if the third fat-acid added possessed a higher melting-point than either of the others. A mixture of 30 parts of palmitic and 70 of myristic acid melts at 462°, and solidifies amorphous. To 20 parts of this mixture stearic acid was added in the following proportions, and melting- point and manner of solidification observed: Stearie Acid. Melts at Manner of Solidification. 45°2° Amorphous. 44'5° 440° 438° 446° 456° 460° 465° ON UM WD »2; To 20 parts of a mixture of 30 parts of myristie with 70 of lauric acid, melting at 35°1°, palmitic acid was added, and the following observations made : Palmitie Acid. Melts at Manner of Solidification. I 339° Amorphous. 2 33'1° er 3 32'2- RR 4 327 s 5 33 er 6 346° ns f! 35'8° en 8 36°0° R 9 Zar Indistinet minute needles. 10 38'8* Minute needles. These tables show clearly that it is important to examine the fractions in the succession in which they were prepared. For instance, supposing the first precipitate to have yielded a fat- acid melting at 68°, which might consequently be considered as stearic acid, the following precipitates fat-acids melting at about 2 18 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. 56°6°, and subsequently one melting at 62°, the conelusion to be drawn is that the last is palmitic acid, and that the fractions with lower melting-points consist of mixtures of stearie and palmitie 'acids. According to Heintz’s table a mixture of equal parts of stearice and palmitie acid should melt at 56'6°, and assume on cooling a lamellar erystalline structure. Should no palmitie acid have been found, but in its stead a fat-acid melting at about 53° to 54°, the presence of myristie acid is to be inferred and the mixture melting at 56°6° would contain about 55 parts of stearie to 45 of myristie acid. It is easy therefore to understand that if these observations be correctly interpreted a rough judgment may be formed of the amount of the separate acids present in the fat. At the ordinary temperature pure siearic acid dissolves in about 40 parts of absolute alcohol, but in much less ether. When suspended in water it may easily be collected and removed by agitation with the latter solvent. The barium and caleium salts are soluble in boiling alcohol, but the major part separates out again on cooling. Palmitie acid dissolves much more easily in warm and cold alcohol, and is very soluble in ether. It may also be collected when suspended in water by shaking with ether. $ 19. Oleic Acid, ete.—The alcoholie liquid from $ 16, which gives no further preeipitate on the addition of acetate of magne- sium and ammonia, may be freed from alcohol by distillation under diminished pressure. That may be accomplished, both in this and many other cases, in the following manner: A retort is charged with the liquid, into which a few pieces of scrap platinum may with advantage be introduced, and attached to a Liebig’s condenser provided with a tubulated receiver, care being taken that all connections are air-tight. The exhausting tube of a Bunsen’s air-pump is then introduced into the tubulure of the receiver. Even if the evacuation be carried to only one-half an atmosphere, aqueous infusions, ete., may be rapidly concentrated on the water-bath and decomposition thus avoided which would other- wise easily be caused by overheating, or by the action of the air, etc. After the recovery of the alcohol by distillation, the residue is poured from the retort, which may be rinsed with a little water, and acidulated with hydrochlorie acid. The fat-acid which col- lects on the surface of the liquid may be removed mechanically, 8 19, 20. CHLOROPHYLL. 19 or by agitation with ether. In examining these acids attention must be paid to the possible presence of members of the oleic-acid series ($$ 130, 131) and of the allied rieinoleic acid. (See also $ 12.) As a preliminary operation an ultimate analysis may be made ; and if this, as well as the reactions of the oil already observed, does not point directly to a particular acid, an attempt must, be made to accomplish a separation either by treating the plaster obtained by heating the fat-acid with oxide of lead, with ether (which dissolves oleate of lead) or absolute aleohol ; or by frac- tionally preeipitating an alcoholie solution of a soda-soap with acetate of barium, or acetate or chloride of caleium ($$ 130, 131). CHLOROPHYLL AND ALKALOIDS EXTRACTED SIMULTANEOUSLY WITH THE FIXED OL. 8 20. Chlorophyll. —The petroleum-spirit extract of vegetable substances often shows a green colour by transmitted light. This is generally due to chlorophyll. Such solutions are usually fluorescent, and appear blood-red by reflected light. Pure chloro- phyll is only slightly soluble in petroleum spirit, and its presence in this extract is accounted for by the influence exercised upon its solubility by the fixed oil. That the green colour is really due to chlorophyll may easily be shown by spectroscopie examination. White light, on passing through a solution of this substance, undergoes a change in various of its constituent colours, as shown by the absorption bands in the spectrum. If the Fraunhofer line A correspond to 17 on the scale, B to 28, C to 34, D to 50, and F to 90, there are observable in the spectrum (compare Table I. to $ 148, Nos. 13 and 14)! four absorption bands situated between B and F, the darkest of which extends from 30 to 42, and the remaining three from 44 to 50, 52 to 56, and 58 to 60 respectively. From 80 to the end the spectrum gradually darkens. Of these absorption bands only the first two can be observed in dilute solutions, and the relative amount of chlorophyll dissolved may be judged from the presence or absence of the others. It would be scarcely possible to obtain absolute values for the amount of chlorophyll present, as liquids containing but very small quantities of that body are comparatively deeply coloured. Moreover, no method has hitherto been found available ! In examining a fresh leaf, only the most marked line between B and C is seen. Compare Vogel, Ber. d. d. chem. Ges. B. xi. pp. 623, 1367 (1878). De) 20 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. for separating chlorophyll from the substances that accompany it. But if series of analyses are to be made with the same plant, to determine the changes it undergoes under the influence of the seasons, or certain conditions of cultivation, etc, the relative quantity of chlorophyll may be estimated by the optical (colori- metrice) method. It is better, however, to use alcohol or ether instead. of petroleum spirit, as the latter does not usually extract the whole of the chlorophyll present. Admixture of foreign colouring matter may be avoided by first extracting the material several times with water, and drying the residue at the lowest temperature possible. The chlorophyll may then be dissolved out by alcohol or ether. (See further in $$ 37, 132.) Under the microscope chlorophyll is seen to be associated with semi-fluid substances allied to protoplasm, often in the form of small granules (the so-called chlorophyll-granules), from which it may be extracted by alcohol. It is more rarely found equally dis- tributed throughout the whole of the protoplasm covering the inner surface of the cell wall. It is bleached by chlorine and eau de Labarraque ; the green colour is changed to yellow by dilute _ acids, and blue by concentrated hydrochlorie acid. 8 21. Alkaloids extracted by Petroleum Spirit. —Parts of plants con- taining alkaloid may, when extracted with petroleum spirit, yield some of the alkaloid, together with fixed oil, to that menstruum, even when the pure alkaloid is insoluble in it. Here, too, it is the fixed oil that determines the solution of the alkaloid. The presence of the latter may be detected by evaporating the petroleum-spirit solution, shaking the residue with water acidulated with sulphurie acid, and separating the aqueous from the oily liquid. Should an emulsion have been formed, separation may be induced by allow- ing the mixture to stand at a temperature of 40° to 50°. The last traces of suspended fat may be removed from the acid liquid by shaking with petroleum spirit, and the presence of alkaloid demon- strated by the usual reagents. (Cf. $ 63.) The amount will not often be large enough to cause a perceptible error in the determi- nation of the fixed oil. But in dealing with very small quantities of alkaloid the estimation of the latter may, under these circum- stances, be appreciably affected ; cases occur in which even the whole of the alkaloid present passes into solution with the oil, and would be overlooked if attention were not paid to this pro- perty of fixed oil. On that account the petroleum-spirit solution $ 22. DETECTION, ETC., OF ETHEREAL OILS. 21 ‚must be treated as above described, and the alkaloid so isolated added to the extraets in which vegetable bases are to be looked for. EXAMINATION OF THE ETHEREAL OlIL. $ 22. Detection and Estimation.—Here, as in $ 11, we will first «discuss the simpler case, viz., that in which the petroleum spirit has removed ethereal, but no fixed oil, or at least only a very small quantity. Like fixed oil, ethereal oil may also be frequently recognised under the microscope as highly refracting globules, or drops of irregular shape, which are soluble in cold alcohol (fixed oil dissolves usually in warm spirit only, if indeed it is soluble at all) and in- soluble in water. Some of them yield even under the microscope several of the characteristic colour-reactions described in $ 142. We have now to estimate the amount of ethereal oil present as aceurately as possible, without using any very large quantity of material. From experiments made by Osse! the following method would appear to be the beste A quantity of the petroleum-spirit solution is accurately measured on to a carefully tared glass dish, which can be closed air-tight. (Cf. $ 9.) I£5 ce. of the solution correspond to 1 gram of substance, 1 to 2 ce. will be found to be sufficient. The glass dish containing the petroleum- spirit solution is then placed under a tubulated glass bell-jar (Fig. 1), 4, with ground edges resting on a ground-glass plate. Two glass tubes are then introduced through the tubulure ; one ‚of them (b) reaches nearly to the surface of the liquid to be evaporated, the other (a) is cut off elose below the cork, and con- nected with an aspirator (BD), so that a current of dry air may be ! Archiv d. Pharm, [3], vii. 104 (1875) (Year-book Pharm. 1876, 562). 22 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. drawn through the apparatus, entering by the tube b, and passing out through «. A chloride of caleium tube (ec) is placed before b, and another between a and B, the former to dry the air entering the apparatus, the letter to prevent moist air from the aspirator passing into 4. These precautions are necessary, for if the atmosphere in which the evaporation of the petroleum spirit is to take place be not completely dried, moisture may be deposited on the glass dish containing the solution, in consequence of the cold produced by evaporation, thus causing, of course, an increase of weight. It is advisable, therefore, to connect the first chloride of caleium tube (c) with a Wolff’s bottle one-third full of concentrated sulphurice acid. A current of air is then passed through the apparatus and the petroleum spirit allowed to evaporate at the ordinary temperature until the operation appears complete ; that is, until the residue has only a slight smell of petroleum spirit. The glass dish is then closed and weighed. After the weight has been accurately taken, it is again opened, exposed for one minute to the air, closed and again weighed, and the alternate exposure and weighing repeated until the same loss in weight is observed twice in succession. This loss is then assumed to be the amount of ethereal oil that diffuses into the air per minute. It is also assumed that during every previous exposure of one minute the same weight of ethereal oil has evaporated, so that to the quantity of oil as found by the last weighing there has to be added the ‘co-eflicient of evapora- tion,’ multiplied by the number of minutes the dish has been exposed. (Compare the examples of estimation in $136.) If the coeflicient of evaporation is less than one milligram this cor- rection may be omitted. Perhaps it would be advantageous to pass a current of carbonic acid through the apparatus during the evaporation of the petroleum spirit, as many ethereal oils diffuse much more slowly into that gas than into atmospheric air. $ 23. In Presence of Fat and Resin.—After thus determining the weight of the substances dissolved in a known quantity of petroleum spirit, it must be ascertained whether the residue after evaporation is completely volatile at 110°, or leaves a non-volatile residue of resinous or fatty matter. Imthe latter case the weight must be determined and deducted from that obtained in $ 22. (See $ 138.) If the non-volatile part constitutes the majority of the dissolved substances it may be ascertained, after the removal 8 23, 24, 25. DISTILLATION OF ETHEREAL OIL. 23 of the ethereal oil by evaporation, whether the residue is now still completely soluble in petroleum spirit. Resins which, in a state of purity, are not dissolved by petroleum spirit, may be taken into solution by means of ethereal oil, just as fixed oil carries with it alkaloids and chlorophyll; they are left undissolved on again treating with petroleum spirit the residue freed from ethereal oil. After having removed by this solvent the fixed oil, ete., thät has been simultaneously extracted, the resin may be weighed alone ($ 146). Of course it is advisable to repeat the experiments described in $$ 22, 23 several times, and take the mean of theresults. I need scarcely say that this method of determining the total ethereal oil does not guarantee any absolute accuracy, but as it is the only one we have at our disposition it might, for the time at least, be deserving of some notice. With less volatile oils, cinnamon, clove, ete., it has yielded very satisfactory results, but less so with terpenes, such as oil of lemon and turpentine., $ 24. Distillation of Larger Quantities of Oil.—I£ a further insight into the composition of the ethereal oil is desired, a larger quantity must be prepared from 5 to 100 kilograms of material. For this purpose distillation in a current of superheated steam is to be recommended, the material having been if necessary previously comminuted and soaked in water. In order that the steam may thoroughly penetrate it the apparatus should be packed with alternate layers of material and straw. A distillate consisting of essential oil and water will be obtained which may be separated from one another in burettes or Florentine flasks. It should not, however, be forgotten that many ethereal oils are tolerably easily soluble in water, and a small quantity of petroleum spirit of low boiling-point should therefore be shaken with suecessive portions of the aqueous distillate. The petroleum spirit is allowed to eyaporate in a current of carbonic acid in the apparatus described in $ 22, and the residue added to the oil separated from the distil- late ($ 137). 5 25. Examination of Aqueous Distillate.—After separation of the oil, the action of the watery liquid on litmus should be tested. It will be frequently found to possess a distinet acid reaction, and contain formic, acetic, or other volatile acids of the Jat-acid series. In such a case the higher acids in the series , may be removed by shaking with ether or petroleum spirit. To 24 SUBSTANOES SOLUBLE IN PETROLEUM SPIRIT. obtain all, including those standing lower in the series, the aqueous distillate may be saturated with soda, concentrated and acidified with sulphuric acid (15). If an oily acid separates from the aqueous liquid, angelic or valerianic acid, or an acid higher in the series, may be looked for. (The test of smell, boiling-point, ete., may be applied, and the ultimate analysis made.) Further in- formation on this point may be found in $$ 139, 140. If the acid liberated is soluble in water, an attempt to separate it by the addi- tion of chloride of caleium may meet with success. Should that not be the case, formie and acetic acids may finally be tested for (be- haviour to mercurie chloride, ferrice chloride and nitrate of silver, the latter also reduced by acrylic acid) as well as salicylous acid. The last-named acid strikes a violet colour with ferric chloride. (See also $ 33.) Salicylous acid may likewise be separated from its aqueous solution by shaking with ether. For hydrocyanic acid see $ 34. Toxicodendric acid,to which Maisch partly attributes the poisonous properties of Rhus toxicodendron, appears to possess great simi- larity with formic, acetic, and acrylic acid. It may be isolated by distillation, and like formic acid reduces nitrate of silver and chloride of gold slowly in the cold, quickly on warming. But it does not reduce mercurous nitrate or chromic acid as formie acid does, nor does it yield the iron reaction characteristic of acetic acid, etc. ; the mercuric salt dissolves with diffieulty in water! (formie acid reduces mercuric to mercurous chloride). $ 26. Salicylie, Benzoic Acid, etc. —It must also be borne in mind that some of the acids of the aromatic series, such as salicylic and benzoie acid ($ 55), are volatile with the vapour of water at temperatures as low as 100°, and may therefore be carried over with the steam in distilling the ethereal oil. On shaking the distillate with petroleum spirit small quantities of salieylic acid are removed, but ether and chloroform may be more advantageously _ employed; the latter liquid is also adapted for the isolation o benzoic acid. On evaporating the ethereal or chloroformie (or petroleum spirit) solution, both benzoie and salicylie acid are obtained as erystalline residues difhieultly soluble in cold water (saliey lie acid about 1 in 300)? The two acids may be dis- 1 Conf. Amer. Journal of Pharmacy, xxxviii. 9 (1866). 2 For particulars of the detection of salieylic acid in Viola trieolor by Mandelin in my lab oratory, see Sitzungsber. d. Dorpater Naturf. Gesellsch. Jg. 1879, p.'77, and Diss. Dorpat., 1881; also Pharm. Journ. and Trans. [3] xüi. 627. & 26, 27. SALICYLIC, BENZOIC ACID, ETC. 184) oa tinguished by their behaviour to ferrie chloride, with which salieylie acid strikes the well-known violet colour. Benzoic acid may be easily sublimed between watch-glasses. Dissolved in a drop of ammonia, the excess of which is allowed to evaporate by exposure to the air, a drop of ferrie chloride produces a brownish tinge. Cinnamic acid may also be similarly distilled over, and separated from the distillate. It may be distinguished from both the fore- going acids by its behaviour to oxidizing agents such as perman- ganate of potassium, with which an aqueous solution yields on warming oil of bitter almonds, whereas benzoic acid yields the same product when acted upon by a reducing agent such as sodium-amalgam. (See also $ 38.) Any cinnamic acid present might in certain cases have been produced from ethereal salts, such as, for example, styracin (einnamate of cinnamyl), or cinnamein (cinnamate of benzy]). Both of these compounds are soluble in petroleum spirit, and are resolved, by decomposition with an alkali, into ecinnamic acid and the respective alcohol. Styraein erystallizes in needles, which, according to Scharling,! melt at 44°. Cinnamein is liquid at the ordinary temperature. The former has an odour resembling vanilla, the latter a faint smell of balsam of Peru. If one of the three acids mentioned has been isolated, special care should be taken to ascertain whether the corresponding aldehyde is also present in the aqueous liquid, viz., salieylie, benzoie (oil of bitter almonds), or cinnamic aldehyde, and whether the acid has not been produced from the aldehyde by absorption of oxygen during or after distillation ($ 33). $ 27. Physical Properties. —The prineipal part of the oil ob- tained by distillation should be completely freed from moisture, filtered and tested with regard to its consistence. If, on standing some time in a freezing mixture, a cerystalline constituent be deposited it should be separated and examined by itself. The action of the oil on polarized light should be observed ($ 141), and uorescence looked for ; if present, it should be ascertained whether warm water will remove a substance fluorescent either alone or on ! Annalen d. Chemie u. Pharm. Ixviii. 168. See also Rügheimer Disserta- tion, Tübingen, 1873 ; Kraut, Annalen der Chemie u. Pharm. clii. 129 (1869) ; Een Journ. Pharm, xlii. 236) ; and Von Müller, Ber. d. d. chem. Ges. Jg. ‚274. 26 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. the addition of caustie potash. Any resin that may have been obtained in the quantitative estimation of the oil ($ 23), should be tested for a fluorescent substance by treating with distilled, or, if necessary, alkaline water ; umbelliferone should be specially borne in mind ($ 43). The resinous constituents, which will be sub- sequently isolated according to $ 36, et seq., may be examined for umbelliferone by mixing with sand and submitting to destructive distillation, or by heating in sealed tubes with alcoholic solution of hydrochloric acid. Further, the specific gravity of ethereal oils should be taken. Westphal’s specific-gravity balance may be advantageously em- ployed for this purpose, especially if the quantity of oil at disposal is rather small. (Cf. $ 141.) | It should also be ascertained what percentage of pure alcohol a spirit must contain to be miscible with the oil in all proportions. A drop only of spirit is first added to the same quantity of oil, and if the resulting mixture is perfectly clear, note should be taken whether the further addition of spirit cause a cloudiness or not. It is, however, only with freshly-prepared oil that such reactions can be considered as characteristic of the oil. Many oils undergo achange on keeping for any length of time, becoming more or less soluble in alcohol, or forming clear mixtures with small proportions, but cloudy with larger ($ 141). $ 28. Reactions.—It is, moreover, desirable to make qualitative experiments with small quantities of the ethereal oil, in order to become acquainted with their behaviour to some few re-agents. For this purpose I have recommended sulphurie acid, alone or applied in combination with sugar, nitre, or ferrie chloride ; nitrie acid, alcoholie hydrochloric acid, solution of bromine in chloro- form, picrie acid, etc. For the results which I myself, and some of my pupils, have obtained with the more important ethereal oils, see $ 142. $ 29. Detection of Sulphaur.—Some ethereal oils contain sulphur, which may be detected by mixing a few drops of the oil with carbonate of soda and nitre, and introdueing it into a piece of combustion tubing, about 15 etm. long, sealed at one end. The upper part of the tube is then charged with a similar mixture of soda and nitre, and the whole ignited as if it were an ultimate analysis in miniature. About one-third of the mass from the bottom of the tube upwards is then dissolved in a little water, 29, 30. CONSTITUENTS OF ETHEREAL OILS. 97 heated with excess of hydrochlorie acid as long as nitrous fumes are evolved, and then tested for sulphurie acid by chloride of "barium. Warming a small quantity of an ethereal oil containing sulphur with a solution of caustie potash of specific gravity 1'3, and adding nitro-prusside of sodium, after diluting with water, often suffices to show the presence of sulphur by the sulphide of potassium formed striking a bluish-violet colour with the nitro-prusside. Some ethereal oils contain nitrogen, and many of these are re- garded as nitriles. This element may be detected by heating a drop of the oil with metallic sodium, dissolving the cooled mass in water, adding a drop of solution of ferrie and ferrous salt, and, after a few minutes, acidifying with hydrochlorie acid, when a precipitate of Prussian blue makes its appearance if nitrogen is present. If the ethereal oil contains a sulphoeyanide (oil of mustard or horse-radish), both the sulphur and nitrogen test must yield a positive result. $ 30. Constituents. —Ethereal oils distilled from vegetable sub- stances are generally mixtures that can be separated into their constituents. If this is to be attempted we must, from the first, admit that, in the present state of our knowledge, an exact quantitative separation is not to be thought of. The prineipal reason for this must be sought for in the ease with which ethereal oils undergo decomposition, and the great disposition many of them show to form polymers. In the majority of cases only one method of separating the constituents of an oil is feasible, viz., that of fractional distillation, which must be repeated until products of constant boiling-point have been obtained. But it is in this very distillation that a change in the oil often takes place, either by the formation of polymers of the original oil with higher boiling-points, or by the production o& hydrocarbons by the liberation of the elements of water from constituents of the oil containing oxygen. An important improvement in these operations might perhaps be made in conducting the distillations under diminished pressure. In order to make this modification available, the temperature must first be ascertained at which the more commonly oceurring eonstituents of oils can be distilled. Many of the terpenes present in ethereal oils may be distilled under the ordinary pressure at 155° to 157°; many of their polymers at about 190°; others at 28 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. about 250°. This knowledge forms, of course, a good basis on which a separation may be attempted. For these and other fractional distillations which may have to be performed in the analysis of plants, small flasks provided with the dephlegmators recommended by Linneman may be used. (Cf. 8 143.) $ 31. Stearoptenes, et. —The following are the more important constituents of ethereal oils that have up to the present time been observed: Terpenes of the composition C,,H,, often boiling at 155° to 157°; polymers of the same, of the formula C,,H,, and C,,Hz, boiling frequently at about 190° or about 250° ; oxygenated compounds of the formula C,,H,,0, CuH1s0; CuH41s0; C,H,40, CH10, C1H1g0; ; hydrocarbons of the formula C,H are more rarely to be found ; still less frequently those of the . ©,H,. series. Of these constituents of oils, it is noticeable that those containing oxygen erystallize in the cold more readily than hydrocarbons of the formula C,,„H,,, and to the former, therefore, our attention must be specially directed in the examination of the cerystalline ‘stearoptenes’ obtained by cooling the oils (with the exception of otto of roses= C,H,,). i If such a stearoptene has been isolated, its purification should be attempted by repeatedly erystallizing from alcohol or ether, pressing the erystals each time between blotting-paper. The co- efficient of refraction may then be ascertained in the alcoholiec solution of the pure substance ; the melting-point, boiling-point, and vapour-density determined ; and, finally, an ultimate analysis made. It should also be ascertained whether hydrocarbons can be obtained by distillation over phosphorie anhydride or chloride of zine. The liquid portions of the various fractions should be subjected to similar experiments, with the exception of the last. It will frequently be found that ethereal oils containing oxygen, as well. as those containing hydrocarbons, of the formula C,,H,, and C,,H,, yield very characteristie colour reactions with the re- agents detailed in $$ 28, 142 ; whilst oils consisting principally of terpenes of the formula C,H}, show less inclination to give marked reactions. These latter oils may often be purified for ultimate analysis by distillation over metallie sodium. $ 32. Other Constituents. —Besides the constituents already men- tioned—which indeed, although frequently agreeing in their 8 33, 34,35. ALDEHYDES, VOL. ACIDS, ETC. 29 composition, have, when prepared from different plants, somewhat dissimilar properties (odour, behaviour to polarized light, ete.)— some ethereal oils contain other substances which may belong to tolerably distant groups. Aldehydes, ethereal salts, alcohols, acids, ete., have been found in various oils. 833. Aldehydes.—l£f an aldehyde is to be looked for in an ethereal oil, it must first be ascertained whether that oil precipitates metallie silver from-an ammoniacal solution of the nitrate.! If this is the case, it must be shaken with a concentrated solution of acid sulphite of soda. The majority of aldehydes are dissolved by acid sulphite of soda, and may be separated from other consti- tuents which do not enter into such combination by removing the aqueous liquil. The aldehyde may then be liberated from com- bination by neutralizing with caustic soda or decomposing with dilute sulphuric acid, and, when thus separated, should be tested as to its physical properties, odour, etc. It should also be ascer- tained if it produces a erystalline precipitate in ethereal solution of ammonia. Finally, an ultimate analysis may be made. Of the aldehydes to which particular attention should be directed, I may mention those of pelargonic, capric and methyl- capric acid, of angelic, cinnamic, salieylic, and benzoic acid ($$ 25, 26). Many, perhaps all, vegetable substances contain- ing chlorophyll, when distilled in the fresh state, appear to yield a substance with the characters of an aldehyde.? $ 34. Volatile Acids.—Acids may be removed from the ethereal oil by shaking with dilute solution of potash or soda, and may be liberated, after evaporation of the solution, by the addition of dilute sulphurie acid. (Of. 8 25, 139.) Besides the volatile acids already mentioned, the possible presence of hydrocyanie acid, which is partially converted into formie acid by shaking with soda, is not to be forgotten. It may best be looked for in the aqueous part of the distillate ($ 25), and recognised by the well-known silver preeipitate and sulphocyanide and Prussian- blue tests. $ 35. Ethereal Salts.—lf an essential oil is t0 be examined for ‚ethereal salts that may be mixed with it, it should be remembered that such salts may be decomposed by heating in autoclaves with 1 See Tollens, Ber. d. d. chem. Ges. xv. 1635 ; Salkowski, ibid, 1739 (1882). * See Ber. d. d. chem. Ges. xiv. 2144, 2508, for an account of this most interesting observation. 30 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT. solution of caustie soda or with baryta-water, yielding a salt of the acid, and the alcohol corresponding to the basic radical contained in them. This latter body may be separated by distillation.! Acetate of octyl, which occurs in the oil of Heracleum, would thus yield an acetate and octyl alcohol. Certain substitution acids, such as methyl-salieylic acid, might be similarly decom- posed ; this, for instance, would yield a salieylate and methylie alcohol. The latter class of compounds would split up on treat- ment with hydriodie acid ; methyl-salicylic acid would thus yield iodide of methyl and salicylie acid. If the alcohols and iodides thus liberated are tolerably freely soluble in water, and therefore not mechanically separable, they must be removed by fractional distillation, in which chloride of calcium and other hygroscopie substances may be often used with success.” Their identification should rest upon the determination of boiling-point and vapour-density, and the ultimate analysis. The same applies in the case of an ethereal oil containing an alcohol a priori. ; Of the alcohols that may be more commonly separated from ethereal oils, methyl aleohol boils at 58°6°, ethyl at 78°4°, propyl at 96°, isopropyl at 83° to 84°, butyl at 116°, isobutyl at 109°, amyl at 130°, pseudo-amyl at 120°, hexyl at 157°, heptyl 175'5° to 177°5°, oetyl at 196° to 197”. To distinguish between a primary, secondary, and tertiary alcohol, V. Meyer and Locher recommend conversion into iodide. "This is mixed with twice its weight of nitrate of silver and a little sand, and distilled, the distillate shaken with strong solution of caustic potash and nitrite of potassium, and then acidified with dilute sulphurie acid. If a primary alcohol is present the mixture will turn red, if a secondary, blue (which may be removed by shaking with chloroform), whilst tertiary alcohols give colourless products of decomposition. In the series of secondary aleohols the reaction succeeds as far as amyl alcohol, in the series of primary alcohols as far as octyl alcohol (Gutknecht).? The acids separated from the ethereal salts, obtained by decom- posing the alkali or barium salt with sulphurie or phosphorie acid, may be examined according to the directions given in $$ 25, 34, 130. 1 Cf. Wanklyn, Chem. News. xxvi. 134. 2 If the ethereal salt yield ethylic alcohol as a product of decomposition, the amount may be directly estimated from the specific gravity of the distillate. 3 See also Heil and Urech, Ber. d. d. chem. Ges. xv. 1249 (1882). $ 36. EXTRACTION OF RESINS AND THEIR ALLIES. 31 ET, EXAMINATION OF THE SUBSTANCES SOLUBLE IN ETHER. RESINS AND THEIR ALLIES. $ 36. Extraction.— After the examination of the substances dis- solved in petroleum-spirit has been carried as far as possible, the residue (ef. $ 9), thoroughly washed with the menstruum, should be removed from the filter (which is to be kept) dried at the ordinary temperature, and then macerated for seven to eight days with pure ether. It is advisable to use the same vessel that has been employed for the treatment with petroleum spirit. If it has been well washed there is no necessity for being minutely particular to bring the whole of the residue on to the filter. The same vessel should, if possible, be reserved for the extraction with alcohol, to be described in $ 47, and the filtration effected throush the same filter that has already done duty for the petroleum spirit and ether extracts. I allow the ether destined for this purpose to stand for several weeks over porous chloride of caleium, and then rectify it after carefully separating the caleium salt. To obtain constant results in such analysis it is necessary to have the ether as free as possible from water and alcohol. Ordinary commercial ether would, for instance, extract a portion of the tannin (sometimes more, sometimes less) from parts of plants containing that substance, whilst ether, purified as described, does not usually produce this effect. As it is not well possible to remove the whole of the tannin with commercial ether, I prefer to refrain from extracting any of it with that menstruum, and remove the whole subsequently with alcohol. To attain this end I avoid the employment of a high temperature in extracting withether. Indeed, I am of opinion that in the course of the analysis of plants, it is better in the majority of cases to 32 SUBSTANCES SOLUBLE IN ETHER. allow the solvent to act at the ordinary temperature. Some instances of special estimations may be excepted in which separate portions of the material may be extracted warm. After allowing the maceration with ether to proceed for about eight days, the first estimation to be made is that of the Zotal substances dissolved, which may be effected by evaporating an aliquot part, or the whole of the extract, in a flat-bottomed glass dish. I usually employ a measured quantity of ether, say 5 to 10 cc., for every gram of substance under examination, macerate in a well-closed flask, and replace any ether that may have been lost by evaporation during the process. After well shaking I take a certain number of cc. of the clear or (cf. $ 9) filtered liquid for evaporation. The residue must be dried at 100° to 110°, till the weight is constant, and this then noted. It should Es ascertained whether any fatty matter which has escaped extraction with petroleum spirit is mixed with the residue, and if this is the case it should, if possible, be removed by wash- ing with the latter liquid, its weight noted, added to the amount found in $ 9, and subtracted from the substances dissolved by ether. It must also be borne in mind that all fats are not neces- sarily soluble in petroleum spirit. It is well-known that castor oil forms clear mixtures with certain, but not all proportions of that solvent.! The remainder of the ethereal extract is filtered from the residual powder, the latter washed, and extract and washings allowed to evaporate at the ordinary temperature The residue of the substance is freed from ether at the same temperature as speedily as possible. 8 37. Chlorophyll.—The ethereal extract may also be tested before evaporation for chlorophyl], as described in $$ 20, 132, ef seg. I have already observed that this substance is more easily and completely removed by ether than by petroleum spirit. 8 38. Portion Soluble in Water.—That part of the ethereäl extract which has been evaporated at the ordinary temperature may, if possible, be powdered or brought into as fine a state of division as practicable by triturating with washed sand or pure siliceous earth (Kieselguhr), and treated with cold water. In the aqueous solution substances soluble in water, such as hematorylin, gallie acid, catechin, pyrocatechin, salieylice acid, benzoic acid, 1 Jahrb. f. Pharm, 1876, p. 369 (Year-book Pharm. 1876, p. 356). ss 39, 40. PORTION SOLUBLE IN ALCOHOL. 33 saliein and other glucosides, and alkaloids may be looked for. The latter, however, may, as a rule, be more easily extracted with water containing acetic or sulphuric acid. A measured portion of the aqueous liquid may be evaporated, and the residue weighed. For the detection of hematoxylin and allied substances see $ 150; of gallie acid, ete., $ 151 ; of salieylie and benzoic acid, 88 26, 34; of glucosides, $$ 54 et seq., 165 ef seq. ; of alkaloids especially, S 63 et seq., L71 et seq. $ 39. Portion Soluble in Alcohol.—The part insoluble in water should be again dried and extracted in a similar manner with absolute alcohol. If the plants under examination contain much resin it will often be observed that a part only of the resinous constituents, etc., dissolves in alcohol. The amount of matter soluble in alcohol, as well as in ether, must then be determined by evaporating the alcoholie solution and weighing the residue. We have thus determined (a) the total substances dissolved by ether, (b) any fat that may have been extracted, (c) the substances soluble in ether and water, (d) substances insoluble in water, soluble in ether and in alcohol, and (e) substances extracted by ether insoluble in water and alcohol. The next step is to obtain a further insight into the nature of the resinous substances soluble in ether alone, as well as those soluble in ether and alcohol. $ 40. Microchemical Examination.—The mieroscopical examina- tion shows that the resins are present partly in the cell wall, saturating it as it were, and partly in the form of exudations either within or upon the cells. Special attention should be paid to their insolubility in water, solubility in alcohol or ether, to the red colour which, according to Müller, is produced with resins by aleoholic tineture of alkanna, violet or blue (Hanstein) by aniline. Some of the reactions enumerated in $ 146 might also be made available for microchemical analysis. In the macrochemical examination it should first be ascertained whether the resin cannot be separated into different component parts by the use of other solvents, such as chloroform, benzene, bisulphide of carbon, acetone, acetic ether, or boiling absolute alcohol, or finally by preeipitating the concentrated ethereal solution with alcohol, petroleum spirit, or other suitable liquid. Similarly, if a substance soluble in ether has not from the first been obtained in erystals, slow evaporation of the solution in the 3 34 SUBSTANCES SOLUBLE IN ETHER. last named solvents (prepared warm if necessary) should be: resorted to in the attempt to cerystallize the substance, or to separate it into a erystalline and an amorphous portion. If the endeavour/to obtain cerystals be successful, the erystalline. form should if possible be determined, and care should be taken to observe whether different erystalline forms can be distinguished under the microscope, rendering it probable that the substance under examination is a mixture. ! $ 41. Behaviour of Iesins to Reagents.—It will further be of special interest to learn whether the substances soluble in ether, insoluble in alcohol and water, are dissolved by alcoholie or aqueous solution of caustic potash, in which case there would be reason to suspect the presence of an acid resin ($ 145). If in- soluble in these liquids it might be assumed that the body under examination is an indifferent resin, or a resin-anhydride not easily susceptible of decomposition. These and the following experiments should be conducted with larger quantities of the substance soluble in ether, specially prepared for this purpose. If an indifferent resin or stable resin-anhydride were present it. might first be purified by recrystallization or reprecipitation, ete., and then an ultimate analysis made. It should be tested for colour-reactions with concentrated sulphurie acid alone and in conjunction with sugar. If ethereal solution of bromine yield a substitution product, its composition should be ascertained. It should also be noticed whether the resin-anhydride is easily oxidized and dissolved by nitrie acid, or whether that takes place only with difficulty ; whether water preeipitates the unchanged resin after the action of the acid, or whether oxidation products are formed ; and if so, whatis their nature, as, for instance, pieric? or oxalic acid ($$ 81, 219), succinie acid ($ 220). $ 42. Action of Fused Potash.—It is further important to become acquainted with the products formed under the influence of fused caustie potash or soda.® The finely powdered substance, in quan- 1 For particulars of a case of this kind, viz. the separation of a mixture of resins obtained from larch-fungus, see Masing, Pharm. Zeitschr. f. Russland, Jg. 9, p. 394 (1870). 2 Bitter yellow erystals belonging to the rhombic system sparingly soluble in cold water, more freely in boiling, soluble i in alcohol and ether. It stains skin and wool yellow, and yields a "plood- red liquid when an alkaline solution is warmed with ceyanide of potassium, sulphide of potassium, or grape sugar. 3 Cf. Hlasiwetz and Barth, Annalen der Chemie und Pharm. cxxxiv. 265; cxxxviii. 61; exxxix, 77. $42, RESORCIN, PHLOROGLUCIN, ETC. 35 tities of not much more than 10 grams at one operation, is mixed with 6 to 8 parts of caustic alkali, and introduced in successive portions into a previously heated silver crucible, and the heat continued, stirring occasionally with a silver spatula until the mass is in a uniform state of fusion. After cooling the contents of the crueible are dissolved in water, and a slight excess of sulphurie or hydrochlorie acid added. The decomposition pro- ducts, which are specially to be looked for, are butyrie and valerianie acid (cf. $$ 25, 34, 139), pyrogallol, phlorogluein, and resorein, benzoic ($ 26), paraoxybenzoic, and protocatechuic acid. The majority of these substances may be removed by ether after acidifying. Volatile fatty acids might be previously extracted by shaking with petroleum spirit. Resorein. — After the fatty acids have been removed by petroleum spirit, resorein may be extracted from the aqueous liquid by shaking with ether and distilling the ethereal solution after sepa- ration. It forms erystals melting at 99°, has a sweetish taste, and strikes a dark violet colour with solution of ferrie chloride, violet with chloride of lime, and rose-red with ammonia. It reduces ammoniacal solution of nitrate of silver. Phloroglucin is also very sweet-tasted, and resembles resorein in many of its reactions, but is coloured reddish-violet with ferrie chloride, and transient reddish-yellow with solution of chlorinated lime. The anhydrous cerystals melt at 220°. Pyrogallol tastes bitter, is soluble in water, alcohol, and ether, melts at 115°, reduces ferrie to ferrous salts, colours the latter blue-black, and separates gold, silver, platinum and mercury from solutions of their salts. An alkaline solution exposed to the air rapidly assumes first a red, then a brown colour ; with lime-water it passes through a transient violet and purplish-red tint. Protocatechwie Acid has an acid reaction, is sparingly soluble in water, strikes no colour with pure ferrous, but yields a dark-green solution with pure ferrice salts. With mixtures of both ferrice and ferrous salts a violet tint is produced. The green liquid obtained by the action of ferric chloride is turned red by potash, and then assumes a violet tint on addition of hydrochlorie acid. It reduces the metal from an ammoniacal silver solution, but is distinguished from the three foregoing substances by not reducing alkaline tar- trate of copper. With acetate of lead it yields a precipitate soluble in acetic acid. 3—2 36 SUBSTANCES SOLUBLE IN ETHER. Paraoxybenzoic Acid melts at 210°, dissolves with diffieulty in cold water, and gives, with ferrie chloride, a yellow precipitate easily soluble in excess. For Orecin and Betaorcin see $ 158.1 $ 43. Dry Distillation of Fesins. —It has already been mentioned in $ 27 that the dry distillation of part of the resin may lead to useful results. Besides the wumbelliferone mentioned in that section, pyrocatechin ($ 151), pyrogallol, ete., should be borne in mind. The first of these substances is fluorescent, and dissolves in boiling water, alcohol, and ether ; the second strikes a green colour with solutions of ferroso-ferrie salts. $ 44. Examination of Portion Soluble in Alcohol. —The remainder of the mixture of resins extracted ‚by ether—that is, the part soluble in alcohol—may be tested as directed in $$ 40 to 43. Acid resins will be found here more frequently than in the portion insoluble in alcohol. If the resin soluble in alcohol dissolves either partially or wholly in an aqueous solution of potash as well, the solution in the latter liquid may be shaken with ether to ascertain if any substance can be removed by that solvent. It was by this means that I isolated peoniofluoresein from peony-seed ($ 147). Chrysophanic acid and allied substances ($$ 148, 149) should also be tested for, as well as quercitrin, quercetin (8 152), and the bodies discussed in $$ 150 to 158. 845. Acids Produced by Action of Alkalies.—Attention must further be paid to the fact that the action of caustic alkalies on certain anhydrides nearly related to the resins-—as, for instance, santonin—may result in the formation of alkali salts, which are not of necessity, on the addition of excess of acetic or hydrochlorie acid, instantly decomposed with reproduction of insoluble anhy- dride. In the case of santonin, santonie acid is liberated on acidulating the alkaline aqueous solution. Any ordinary acid resin mixed with it may be removed by preeipitation with hydro- chlorie or acetic acid and immediate filtration. The santonin is deposited only after standing several days, but can be extracted at once by shaking with chloroform. A method that I have pro- posed for the estimation of santonin is based upon this fact, and will be described in $ 154. $ 46. Direct Extraction with Ether.—A portion of the powdered material may, without further treatment, be extracted with ether, 1 For ferulic acid compare Jahrb, f. Pharmacie, 1866, p. 95. $46. DIRECT EXATRACTION WITH ETHER. 37 and the substances thus dissolved estimated. In the majority of cases the weight will be the same as the sum of the substances extracted by petroleum spirit according to $ 9, and ether according to $36. If there is a deficiency, the residue should be treated with petroleum spirit, in which case attention would be directed to a substance other than an ethereal or fixed oil. The residue after exhaustion with ether, and, if necessary, petroleum spirit, may be dried and boiled with chloroform or bisulphide of carbon, to ascertain if such substances as caoutchouc, ete. can be extracted ($ 127). 38 SUBSTANCES SOLUBLE IN ALCOHOL. IV. EXAMINATION OF THE SUBSTANCES SOLUBLE IN ABSOLUTE ALCOHOL. RESINS, TANNINS, BITTER PRINCIPLES, ALKALOIDS, GLUCOSES, ETC. $ 47. Extraction.—The residue of the substance under examina- tion after exhaustion with petroleum spirit and ether (cf. $ 36) is removed from the filter, dried at the ordinary temperature, and treated with 10 cc. of absolute alcohol for every gram of original substance. After the lapse of five to seven days the alcohol lost by volatilization is replaced, and the whole well shaken. It is then filtered through the same filter that has been used for the previous operations, any evaporation of alcohol being prevented as carefully as possible. A measured quantity of the filtrate is next evaporated in a tared platinum dish and dried until the weight noted is constant. Itis then incinerated, and the ash deducted from the weight of the dry substance. After having thus estimated the Zotal organic matter insoluble in petroleum spirit and ether, but soluble in alcohol, the residue on the filter may be washed with absolute alcohol, and the washings, with the remainder of. the filtrate, concentrated. This may best be done by distilling in a flask, under diminished pressure. The liquid remaining after distillation is poured into a glass dish, and allowed to eva-- porate, at the ordinary temperature, over sulphurie acid. 848. Estimation of Portion Soluble in Water. —The dry residue thus obtained is first treated with a measured quantity of water. To ascertain the amount soluble in this menstruum, as well as in alcohol, a measured quantity of the solution is similarly evapo- rated, dried at 110°, and weighed. j The remainder of the aqueous extract is reserved for the experiments detailed in S$ 49, 50, 70; that which is insoluble in ro Br’ ss 48, 49, 50. DETECTION OF TANNIN. 39 water is treated with water containing a little ammonia (1 in 50) as long as anything is removed. The ammoniacal extract may be evaporated with a slight excess of acetic acid, the residue rinsed on to a filter with a little water, washed, dried, and weighed. The brownish mass thus left on the filter is, as a rule, to be regarded as phlobaphene ($ 108; see also SS 160, 163), re- sulting from the decomposition of tannin. The portion of the aqueous extract insoluble in ammoniacal water may be again dried over sulphuric acid, and then subjeceted to similar treat- ment as the resin soluble in ether (cf. $ 39 to 45 ; 145, 146). I there is reason to suspect the presence of an alkaloid soluble in alcohol, but insoluble in ether, the residue, after treatment with ammoniacal water, may be digested with water containing a little sulphuric acid. (For alkaloids see 8 55, et seq.; 63,et seq. ; 171, et seq.) EXAMINATION OF THE TANNIN. $ 49. Detection. —If the aqueous solution obtained from the evaporation residue of the alcoholie extract is coloured blue-black by a ferroso-ferrie salt and precipitated by gelatine, solution of acetate of lead is t0 be added in slight excess. The resulting pre- eipitate is immediately collected on a tared filter, washed with water (not too long, three or four times, with 3 to 5 cc.), dried, and weighed (852, L). It is then removed from the filter, which is burnt in a porcelain crucible with a little nitrate of ammonia ; the precipitate itself is next incinerated, and the whole finally ignited in the blow-pipe flame until the weight is constant. This is then deducted from the weight of the preeipitate, and the re- mainder noted as tannie acid, or bitter principle preeipitated by oxide of lead, or vegetable acids preeipitated by lead ($80). The filtrate from the lead preeipitate is treated according to $ 70. $ 50. Detection continued.—The same treatment is repeated with a similar quantity of the watery extract obtained in $ 48, substi- tuting acetate of copper for acetate of lead ($ 52, IL). Here, too, the amount of oxide of copper in the preeipitate is to be determined by following the same directions and deducted from the weight of the preeipitate. If the estimation with the copper salt yields the same result as that with the lead, it is tolerably certain that only tannie acid has been preeipitated. But if lead throws down more matter than copper we are generally justified in assuming that the former preeipitates substances other than 40 SUBSTANCES SOLUBLE.IN ALCOHOL. tannin, such as other acids, or bitter prineiples, the amount of which may be approximately determined by deducting the weight of the organie matter contained in the copper precipitate from that contained in the lead. Under these cireumstances the weight of the organic substances precipitated by copper sometimes re- presents approximately the tannin contained in the material (ss 52, 80). It must, however, be admitted that the great differ- ence in the tannins occurring in nature prevents such a result being looked for in every case. '»$ 51. Keactions.—The following reactions are common to all tannins : they are preeipitated from aqueous solution by gelatine, by many albuminous substances, by acetate of lead and copper, stannous chloride, etc. ; they reduce, at least when warm, alkaline solution of copper as well as solutions of gold and silver salts; they strike an inky or dark-green colour with ferroso-ferrie salts and transform skin into leather. Some tannins are precipitated by mineral acids, by tartar emetic and by alkaloids, but it is frequently observable that an alkaloid and tannin which 'occur together in the same plant do not form an insoluble compound. For the microscopic detection of tannin the reaction with iron salts may be made use of. ÜCells containing tannin are moreover coloured reddish-brown with bichromate of potash, violet-red with aniline and reddish or violet with dilute solution of chloride of zinc and iodine. (See note to $ 249.) The great difference shown by the various tannins ($ 159 ei seq.) makes it exceedingly diflicult to give any general rules for their estimation. Some of my pupils! have therefore at my instance tssted the behaviour of the more important tannins to the re- agents that have been recommended for their quantitative estima- tion. Before I give a short resume of the results they have obtained I should like to observe that, in my opinion, the estima- tion of the tannin in the alcoholie extract, prepared as I have described, is preferable to the determination in the aqueous ex- tract, provided of course that the material is very finely powdered, that the tannin is insoluble in ether free from alcohol, and that the alcoholic liquid has been evaporated under diminished pressure 1 Compare Günther, Pharm. Zeitschr. f. Russland, Jg. 1870, pp. 161, 193, 225, and ‘ Beiträge zur Kenntniss der in Sumach, Myrobalanen etc. vorkom- menden Gerbsäuren,’ Diss. Dorpat, 1871, and other Dorpat dissertations sub- sequently referred to, ss 51, 52. ESTIMATION OF TANNIN. 4 and dried as directed in $ 47. One advantage in employing alcohol to extract the tannin, as already recommended by Loewe, is the exelusion of the vegetable mucilage (so-called pectin) and similar substances which may under certain conditions introduce a very great error into the estimation. Another reason in favour of the use of alcohol is to be found in the fact that, if the material contains a large quantity of albuminous matter, water will fre- quently only partially remove the tannin, and that many tannins are much more easily decomposed by evaporation in an aqueous than in an alcoholic solution. It may happen, it is true, that cold absolute alcohol will not in some cases extract the whole of the tannin from vegetable substances that are very rich in albumen, but even in such cases I would prefer treating the residue, after extraction with ether, with boiling alcohol to exhausting it with water. (See also $$ 95, 162.) Special emphasis must, however, be laid on the importance of getting rid of the whole of the alcohol by distillation, if that men- struum has been employed, as almost all the following determina- tions of tannin are made in aqueous solution, and the admixture of even small quantities of alcohol might cause great error. $ 52. Let us now review the more important methods that have been recommended for the estimation of tannin. I. Acetate of Lead.—Pribram! has proposed precipitation with neutral acetate of lead. If care be taken not to introduce too great an excess of the precipitant, the precipitation of most tannins is tolerably complete, and it is only in the case of gallo- tannic acid, catechu-, kino-, and caffeo-tannie acid that part remains in solution on account of the slight solubility of the lead salt. But as the precipitates are not invariably of constant composition it is difficult to estimate the tannin by titration with lead solution. Dome of the precipitates (tannic acids from oak- and willow-bark)) are decomposed by prolonged washing with water, the tanniec acid partly passing into solution and undergoing change. It was for these reasons that I have recommended the preeipitation to be made in not over-dilute solutions, and directed that the washing should not be continued too long, and that the tannin should be deter- ! Zeitschr. f. anal. Chemie, v. 455 (1866). Compare also Jacobson, Chem. techn. Repert. 1866, ii. 85 ; Stein, Schweiz. polyt. Zeitschr. ii. 169 ; Gietl, Zeitschr. f. anal. Chemie, xi. 144 (1872) ; and Schmidt, Zeitschr. d. österr. Apothekervereins, xii. p. 374 (1874) ; (Am. Journ. Pharm. 1874, 427). 42 'SUBSTANCES SOLUBLE IN ALCOHOL. mined from the organic matter in the dried precipitate. In this way the tannin in rhatany, tormentilla, sumach, divi-divi, myro- balans, knopper-galls, oak-bark, and willow-bark may generally be satisfactorily estimated. Gallo-tannie acid at times also yields good results. II. Acetate of Copper has been suggested by Sackur! as a precipitant for tannin. The composition of;’the precipitate is, however, seldom constant even when working with the same tannic acid ; and here, too, it has proved advisable to preeipitate in tolerably concentrated solutions, not to wash too long, and to estimate the tannin gravimetrically, as above described. IlI. Stannous C’hloride and Ammoniacal Stannous Chloride, which have been recommended by Risler-Beunat? and Persoz,3 for the estimation of tannin, preeipitate most tannic acids less completely than the two foregoing reagents. The precipitates moreover form slowly, but are in the majority of cases tolerably constant in composition. On account of the solubility of the precipitate in water, the estimation will here, too, be most accurate when the washing is not continued too long, the preeipitate dried, impreg- nated with nitrate of ammonia, ignited, and the resulting oxide of tin weighed. The loss by ignition gives the weight of the tannin. But since the advantage in obtaining preeipitates of «constant composition cannot compensate for the deficiencies of the method already mentioned, I have not further thought of employ- ing the precipitation with stannous chloride for the purposes we have now in view. IV. Tartar Emetic, which has been recommended by Gerland® and Koller? for the volumetrie estimation of tannin, will yield 1 Gerberzeitung, xxxi. 32. See also Wolff, Krit. Blätter f. Forst und Jagdwissensch. xliv. 167 ; Fleck, Wagner’s Jahresber. f. techn. Chem. Jg. 1860, p. 531 ; Haliwachs, Zeitschr. f. anal. Chem. v. 234 (1866). 2 Zeitschr. f. anal. Chem. ii. 287 (1863). ? Traite de I’Impression des Tissus, i. 282, The results obtained by the method recommended by Persoz, in which the amount of tannin is calceulated from the volume of the precipitate, are, according to Gauhe (Zeitschr. f. anal, Chem. iii. 130, 1864) and Cech (Stud. über quant. Best. der Gerbsäuren, In- augural Dissertation, Heidelberg, 1867), too high. I avail myself of this opportunity to draw attention to the works of the two last-named authors, which are intended as a critical review of the more important methods of estimating tannie acid. (See Procter, Pharm. Journ. Trans. [3], vi, 1020 ; Allen, Commercial Organic Analysis, London, 1879.) 4 N, Jahrb, f. Pharm. xxvi. 20 (1866) ; (Amer. Journ. Pharm. xxxv. 519). 5 Koller employed this method in estimating the tannic acid in orange-peel (N. Jahrb. f. Fharm, xxv. 206, 1866). 52. ESTIMATION OF TANNIN. 43 satisfactory results in some few cases only, because, even if the solutien be mixed with chloride of ammonium, it is diffieult to ascertain when a sufficient quantity of the reagent has been added, and because some of the tannin preeipitates so produced are rapidly decomposed. Some tannins (rheo-tannic acid) are not precipitated at all by tartar emetic. V. Ammoniacal Solution of Acetate of Zine. — This reagent should, according to Terreil,! Carpene,? and Barbieri,? be used in the following manner for the estimation of tannie acid. The liquid to be precipitated is brought to the boiling-point, an excess of the zine solution added, and, after concentration by evapora- tion, the mixture is cooled and filtered. The precipitate is then dissolved in sulphurie acid, and the tannin estimated by titration with permanganate of potassium. I must admit that some tannie acids may be determined in this manner, but I must also draw attention to the fact that all tannins occurring in vegetable substances do not exercise the same influence on permanganate of potassium ; that is, one tannic acid may differ from another in the amount of permanganate a given quantity can decolourize, and this value of the tannin in terms of permanganate must in many cases be first determined. It is partly on this account that the estimations of the tannin in wine, made according to this method, are of but little value. VI. Ferric Acetate, in conjunction with acetate of soda, has been used by Handtke for the estimation of tannie acid in oak-bark, valona, divi-divi, sumach and catechu. He found the reagent un- suited for the precipitation of the tannin present in Rheum, various species of Filex, coffee and other plants; and even with the first- named substances it was only when the concentration was such that the preeipitate contained 458 per cent. of oxide of iron that the estimation yielded satisfactory results. Still less feasible is Wildenstein’s® colorimetrie examination, which is based upon the intensity of the colour produced by the solution on paper impregnated with ferric citrate. VD. Titration with Permanganate of Potassium..—Monier,® Cech,” ! Zeitschr. f. anal. Chem. xiii. 243 (1874). ® Ibid. xv. 112 (1876), ® Ibid. xvi. 123 (1877). See also Kathreiner, ibid. xviii. 113 (1879). * Journ. f. pr. Chem. Ixxxi. 345. ° Zeitschr. f. anal. Chemie, ii. 137 (1863). % Compt. rend. xlvi. 447. 7 Loc. cit. 44 SUBSTANCES SOLUBLE IN ALCOHOL. Löwenthal,! and others, have shown that the tannin contained in many vegetable substances may be estimated with sufficient accuracy for technical purposes by titrating with solution of per- manganate of potassium. In dealing with vegetable infusions, however, almost all authors agree that if a satisfactory result is to be obtained the solution to be titrated must be very dilute (about 1 in 400), and the oxidation incomplete. Löwenthal and others have found the following to be the most advantageous method of procedure. The liquid under examination is mixed with a measured quantity of solution of indigo-carmine, the value of which, in terms of permanganate, has been previously determined. The perman- ganate solution is then run in till the blue colour changes to green. The value of the pure tannin in terms of the reagent must have been previously determined by experiments with weighed quanti- ties of the same. By such experiments Günther ascertained that 16 parts of oxygen from the permanganate oxidized 32°5 parts of gallo-tannic acid, 33°0 of sumach-tannie acid, 25°0 (5°54) of catechu-tannie acid, 24°0 (532) of catechuic acid,” 280 of kino- tannic acid, 34 to 37 of rhatania-tannie acid, 35 of tormentilla- tannic acid, 34 of caffeo-tannic acid, and 32 of oak-bark-tannic acid. Neugebauer? estimated the tannic acid in oak-barks with per- manganate by taking advantage of the power possessed by animal charcoal of absorbing tannic acid, and thus removing it completely from its aqueous solution. He divided the infusion to be ex- amined in two equal parts. The one was titrated direct with permanganate, the other after the absorption of the tannie acid by animal charcoal. The amount of tannin present was then calculated from the difference, the assumption being made that the substances which acted upon permanganate in the liquid after treatment with animalcharcoal were foreign bodies. Löwenthal (see below) titrates a part of the tannin solution direct, another part after precipitation with solution of gelatine (X11.). From the differ- ence in the quantity of permanganate used the tannin is caleulated. 1 Journ. f. pr. Chem. Ixxxi. 150, 2 Owing to a mistake in the calculations, the figures here given for catechu- tannic acid and catechuic acid are much too high. The correct numbers are placed in brackets after them. Lehmann, in checking the experiments (Vergl. Unters. einiger Catechu- und Gambier-Proben. Diss. Dorpat, 1880), found that 16°0 parts of oxygen were equivalent to 5'14 parts of catechu-tannic acid and 4'84 catechin. 3 Zeitschr. f. anal. Chem. x.1 (1871). 852. ESTIMATION OF TANNIN. 45 If a solution contain both gallice and tannie acid, or catechin and catechu-tannic acid, both may be approximately estimated by Löwenthal’s method. (See also $ 164, et seg,) The addition of gelatine as directed by him introduces only a slight source of . error, which may be generally neglected. VIII. Chlorinated Lime —Löwenthal! has titrated with chlori nated lime in the presence of indigo carmine in the same way as with permanganate of potassium, but the estimations generally yield too high results in consequence of the impurities present. Cech? has already expressed an unfavourable opinion of the propositions of Commaille? and Millon* to make the separation of iodine from iodic acid by tannin the basis of a method for its quantitative estimation. The decolourization of a solution of iodine by tannie acid in the presence of carbonate of soda has been recommended by Jean? for the quantitative estimation of tannin. He states that 1 part of gallo-tannie acid decolourizes 4 parts of iodine, and reserves to himself the determination of the value of other tannins in terms of iodine. He admits that gallie acid also acts upon iodine, and advises, when both are pre- sent, first to make a total estimation, and then determine the gallic acid alone in a second portion of the liquid, after the tannic acid has been removed by gelatine or hide The solution of tannie acid for standardizing should contain 1 part in 1,000 of water. Before titrating, 2 ce. of a 25 per cent. solution of cryst. carbonate of soda should be added for every 10 ce. of tannic acid solution. It must be observed that here, t00, many organic com- pounds would act in a similar manner to tannin. IX. Oxidation. —For the estimation of tannin Mittenzwey® has availed himself of the fact that an alkaline solution of tannie acid rapidly absorbs oxygen from the air. In the analysis of plants this method will seldom be of any value. Cech has already shown that it yields unsatisfactory results with the tannins usually employed. X. Titration with Cinchonine.—Wagner” has proposed titration with sulphate of cinchonine, using acetate of rosaniline as an & Roc. ch, 2 Loc. cit. 3 Compt. rend. lix, 599 (1864). * Annales de Chimie et de Phys. [3], xii. 26. 5 Zeitschr. f. anal. Chem. xvi. 123 (1877). 6 Journ. f. pr. Chemie, xci. 81, and Zeitschr, f. anal. Chemie, iii. 484 (1864). See also Terreil, Zeitschrift des österr. Apothekervereins, Jg. xii. 377 (1874). 7 Zeitschr. f. anal. Chem. v. 1 (1866). Seealso Salzer, ibid. vii. 70 (1868) ; Buchner, ibid. 139 ; Clark, Amer. Journ. Pharm. xlviii. 558 (1876). % 46 SUBSTANCES SOLUBLE IN ALCOHOL. indicator. But the majority of those who have worked the process have failed to obtain good results. Almost all of them have found that the assumption that rosaniline would not colour the liquid until all the tannin had been precipitated by the einchonine, was true: of certain tannins only, and not of all. It has been shown that, with some tannins, the appearance of a red tinge in the solution, - which is said to indicate the end of the reaction, may be noticed long before all the tannic acid has been preeipitated. In many cases better results might be obtained with cinchonine if the tannic acid were preeipitated by an excess, the liquid filtered and the excess of cinchonine in the filtrate determined by titration with potassio-mercuric iodide. This method has been adopted by Clark in estimating the tannie acid in tea. (See $ 65.) XI. Gelatine and Hide —The behaviour of gelatine and hide to tannic acid is often made use of in the estimation of tannin. The estimation may be made either by determining the increase in weight of a piece of hide, previously freed from substances soluble in water and petroleum spirit by digestion in those solvents, when allowed to lie for some time in the solution of tannin, or by ascertaining the specific gravity of the solution before and after the absorption of the tannic acid, and calculating the amount from the difference. Hammer! has constructed a table for gallo-tannic acid, from which the ameunt of tannin can be directly read off. If this method of estimation is to be adopted, a similar table would have to be constructed for other important tannic acids, showing the relation between the difference in specific gravity and the amount of tannin present. XI Gelatine : Gravimetric Process. —Preeipitation of the tannin by gelatine, and caleulation of the amount present from the weight of the precipitate, has also been tried. But the disadvantages which present themselves here are that these preeipitates are neither sufficiently insoluble nor constant enough in composition to allow of their being made the basis of a gravimetric estimation ; especially in washing the precipitate with pure water, considerable quantities of tannie acid are removed. It is, therefore, most advantageous to apply the preeipitation 1 Journ. f. pract. Chem. elxxxi. 159. See also Löwe, Zeitschr. f. anal. Chem. iv. 365 (1865), and Hallwachs and Cech (loc. eit.). Davy has already estimated tannic acid gravimetrically by employing hide (Chem. News, 1863, p. 54, and Zeitschr. f. anal. Chem. ii. 419). ss 52, 53. @ALLIC AND CATECHUIV AUIDS. 47 with gelatine in the following manner : A solution of that sub- ee value of which, in terms of the tannic acid to be esti- mated, has been previously ascertained—is run into the solution in which tannin is to be determined as long as precipitation occurs. The gelatine solution should be a with some salt, diminishing the solubility of the tannate of gelatine. For the latter purpose the addition of alum has been recommended (Müller!). The proposal of Schulze? to use chloride of ammonium, or of Löwenthal to add common salt and „}; vol. of hydrochloric acid (specific gravity 1'12), appears Ms A solution of gallo- tannic acid may be saturated with these salts; but in the case of other tannins (from oak, willow, and elm bark) a smaller quantity might be preferable If Löwenthal’s modification be adopted, it is advisable to stir the liquid vigorously for five minutes after each addition of the gelatine solution. It has already been determined by Günther that the various tannins differ in the amount of gelatine they are capable of preeipitating. He found that 100 parts of gelatine precipitate, in the presence of chloride of ammonium, 77 parts of gallo-tannic acid (according to Johanson 120 parts of dry tannic acid), 132 (Lehmann, 139) of catechu-, 130 kino-, 130 to 132 rhatania-, 130 oak-bark-, and 168 of tormentilla-tannice acid. As is well-known, gallic and catechuic acids do not precipitate gelatine. 8 53. Gallic and Catechwie Acids.—I£ one of these two substances is to be looked for, the tannie acids should be first preeipitated by gelatine, the excess of gelatine by alcohol ; and after the alcohol has been removed by distillation under diminished pressure, gallic or catechuic acid may be isolated by shaking with ether or acetic ether. If care has been taken to avoid using a large excess of gelatine, the treatment with alcohol might be omitted ; and in many cases it would be possible to agitate even the aqueous solu- 1 Archiv d. Pharm. xxxviii. 147 (1845). Gauhe did not succeed in his en- deavour to find an indicator (iodide of starch) to show the final reaction in titrating. Compare Zeitschr. f. anal. Chem. v. 232 (1866). Neither was Cech quite satisfied with an iron solution used for the same purpose. See also Hallwachs (loc. eit.). 2 Zeitschr. f. anal. Chem. v. 455 (1866). Compare also Salzer, ibid. vii. 70 (1868), and Johanson, ‘ Beitr. z. Chemie der Eichen, Weiden, und Ulmenrinde,’ Diss. Dorpat, 1875, pp. 72,76. Also Lehmann (loc. cit.).. A more recent eritical review of the more important methods for estimating tannic acid by Löwenthal will be found in the Zeitschr. f. anal. Chemie, xvi. 33, and 201 (1877), and xx. 91 (1881). 48 SUBSTANCES SOLUBLE IN ALCOHOL. tion ($ 48) directly with ether, renewing the solvent four or five times. On evaporating the ethereal solution, both gallie and catechuic acids remain behind in a cerystalline form, generally needles felted together. (Cf. $ 151, 165.) The weight of the dried residue frequently indicates with tolerable accuracy the quantity of the substance present ; but if the residue be mixed with much colouring or amorphous matter, so as to cause some hesitation in accepting the weight as correct, the result obtained may be verified by titration with permanganate of potash. (See above.) If the material has been extracted with ether previous to treating with alcohol, gallic and catechuie acids will be found in the aqueous solution from the ethereal extract. «C#. 8 38, 151.) For the free vegetable acids which may occur in the aleoholie extract see $ 82. (See also in $ 159.) EXAMINATION FOR GLUCOSIDES, BITTER PRINCIPLES, ALKALOIDS, ETC. $ 54. Extraction by Agitation.—l£ no tannic acid or allied sub- stance has been found in the aqueous liquid ($ 48), but by the bitter taste or other properties the presence of a bitter principle, glucoside or alkaloid insoluble in ether but soluble in water is suspected, the watery solution prepared from the evaporation residue of the alcoholie tineture may be subjected to consecutive treatment with various liquids which, being themselves insoluble in water, are adapted for removal of substances in solution by agitation and separation. The aqueous solution from the ethereal extract ($ 38) may also be treated in a similar manner. The use of petroleum spirit, benzene, and chloroform may be especially recom- mended for this purpose ; they should be employed in the order in which they are named, and the liquid should be rendered first slightly acid with sulphuric acid, and subsequently alkaline with ammonia; I have spoken at length on this subject in my “Ermit- telung der Gifte.’ After each agitation, the solvent should be separated, washed once by shaking with pure water, again separated, evaporated to dryness, and the residue examined. Ifa solvent, as for instance petroleum spirit, removes any appreciable quantity of a substance, the agitation with this liquid should be ı P, 119. Compare also Russ. Archiv für gerichtl. Med. J. i. und Pharm. Zeitschr. f. Russland, v. 85 ; vi. 663. 54, 55, 56. FROM ACID SOLUTION. 49 repeated until only traces of the substance are dissolved. Then, and not till then, the same treatment is repeated with the next solvent, and so on. All liquids employed for agitation must be rectified shortly before being used. Petroleum spirit must be as volatile as possible; benzene should boil constantly at 81° C., and yield nitro-benzene when treated with fuming nitrie acid. $ 55. From Acid Solution. —Of the better-known bitter prin- ciples, acids and alkaloids removed by petroleum spirit from an acid solution, the following may be mentioned: Salieylic acid (cf. $ 26). FPungent principles of capsicum, etc. (s 126). (Both of these would have been already detected in the ethereal extract. Salicylic acid may be more easily removed by benzene or ether.) Piperin—the majority of this principle will be found in the part of the alcoholic extract insoluble in water (compare further 8 171, 178). Absynthin, cannot be . completely removed by petroleum spirit ($ 156). Hop-resin ($ 156). Benzene removes from the same solution santonin (cf. $ 154); caryophyllin ($ 156) ; eubebin ($ 155) ; digitalin (remains principally in that part of the ethereal extract which is insoluble in water (ef. $ 155); gratiolin ($ 167); cascarillin ($ 156) ; elaterin ($ 156) ; populin ($ 167) ; colocynthin ($ 167); absynthin ($ 156); quassin (S 156); menyanthin ($ 167); ericolin ($ 155); daphmin ($ 167); bitter principle of Onicus benedictus ($ 168); caffeine (8 171, 176); piperin (see above); colchiceine ($ 171); berberine is dissolved by benzene in small proportion only (compare $ 171). Besides the substances already named as being dissolved by petroleum spirit and benzene, chloroform removes also among ethers: Benzoic acid (cf. $ 26); digitalein (sparingly soluble in ether, $ 155); convallamarin ($ 167) ; saponin (insoluble in ether, diffieultly soluble in absolute aleohol, $ 77 et seq., 167) ; senegin (the same) ; physalin ($ 167); syringin ($ 167); esculin (8 167); : pierotoxin ($ 155); helleborein ($ 167); cinchonine (is insoluble in ether, $$ 171, 182, 184); theobromine (8 177 ); ‚papawverine ($ 171); narceine ($ 171). Colchieine, solanidine, quebrachine, geissospermine. S 56. From Alkaline Solution.—After the last agitation with chloroform the aqueous liquid should be shaken whilst still acid with petroleum spirit. This removes the small quantity of chloroform remaining dissolved by the watery liquid. An error 4 50 SUBSTANCES SOLUBLE IN ALCOHOL. might be made in omitting this treatment, since on rendering alkaline and shaking with petroleum spirit this solvent would take up a little chloroform and would consequently be no longer pure. After, therefore, the remainder of the chloroform has been removed by petroleum spirit, the liquid may be made alkaline with ammonia, and the agitation with the same solvents repeated in the same order. In addition to these three liquids I have, however, after agitation with chloroform, employed amylic alcohol for detecting certain poisons. It removes morphine, solanine, ($ 171), salicine ($ 167), and some other substances from their aqueous solutions with special facility. It is principally alkaloids that are removed by petroleum spirit, etc., from ammoniacal solution. Petroleum spirit dissolves, for instance, traces of sirychnine, brucine, emetine, veratine, sabadilline, and sabatrine. All these substances are, however, more easily and completely taken up by benzene and chloroform. But petroleum spirit is specially valuable in the examination for the so-called volatile and, at ordinary temperatures, liquid alkaloids, such as coniine, methylconiine (and conhydrine), nico- Zine, lobelüne, sparteine, alkaloids in ypimento, capsicum and Sarracenia purpurea. Aniline, trimethylamine, and allied sub- stances are also dissolved by it ($$ 171, 239). Im examining for volatile alkaloids I have advised agitation of the aqueous liquid with petroleum spirit, and evaporation of the solvent, after sepa- ration, at a temperature of about 20°, on glass dishes previously moistened with strong hydrochlorie acid, on which the hydro- chlorides of the alkaloids will partly, at all events, remain behind. A freshly-prepared dilute solution of hydrochlorie acid gas in ether may be advantageously substituted for the usual aqueous acid. Benzene removes from ammoniacal solution, in addition to the alkaloids already mentioned, atropine, hyoscyamine, physostigmine, pilocarpine, gelsemine, taxine, quimidine, narcotine, codeine, thebaine, delphinine and delphinoidine, aconitine, aspidospermine, pereirine, and a trace of cinchonine. (Cf. $ 171.) In addition to these, again, chloroform dissolves from ammoniacal solution cinchonine, papaverine, narceine, mupharine, the alkaloids of celandine, and small quantities of morphine ($ 171). 857. Direct Tests for @lucosides, Alkaloids, et.—The number of acids, glucosides and alkaloids (cf. $ 21) that may be isolated by ss 57, 58. DIRECT TESTS FOR ALKALOIDS, ETC. 51 this method of agitation is doubtless very large, and by making the required experiments the list given in the preceding section might be rendered far more complete. It is this very fact that renders the method so suitable for the qualitative exami- nation of those plants and parts of plants the constituents of which are at present unknown. Of course, it is possible to employ infusions which have been prepared by digesting the material under examination with water on the water-bath, instead of aqueous solutions from the ethereal or alcoholic extracts. This would especially be the case if acids, bitter prineiples and gluco- sides are to be looked for. Alkaloids may likewise be tested for by digesting the material with water acidulated with sulphurie acid (l in 50). In both cases, however, it must be remembered that by thus directly extracting the substance with aqueous liquids many bodies, such as mucilage, etc., are dissolved, and that this is avoided by treating them according to the method first. de- scribed. The presence of such substances is disadvantageous, inasmuch as they sometimes render the extraction of a principle from aqueous solution by the method of agitation more difficult, and always act injuriously in rendering the separation of the two liquids after shaking almost impossible. It is therefore advisable to remove all matter tending to increase the viscosity of the aqueous infusion by concentrating to a syrupy consistence (if necessary, after having previously nearly neutralized with ammonia or magnesia), preeipitating with about three volumes of spirit, filtering after standing twelve to twenty-four hours in acold place, and distilling off the alcohol. $ 58. Alkaloids, ete., not Bemovable by Agitation.—Some bitter principles, glucosides and alkaloids cannot, however, be removed from solution by agitation, either because they have less tendency to pass into any other known liquid than to remain in aqueous solution, or because they are insoluble in water. The latter is the case, for instance, with the glucosidal resins which occur in the convolvulacex. Such substances are generally isolated with the resins. (Cf.$ 153.) The purification of bitter prineiples and glucosides that are soluble in water, but cannot be removed by shaking, may be effected by evaporating the aqueous solutions prepared from the ethereal or alcoholie extracts, and repeatedly dissolving the sub- stance in chloroform, alcohol, or ether. It will be found easier to 4—2 52 SUBSTANCES SOLUBLE IN ALCOHOL. purifyabitter principle dissolved by water from the ethereal extract, than one obtained in a similar manner from the aleoholic extract, since the latter contains glucoses and tannins, which are insoluble in ether. Apart from the treatment with chloroform and other solvents which I have just described, another method of purifica- tion may in this case be adopted—viz., evaporation of the aqueous solution, extraction with the smallest possible quantity of absolute alcohol, and precipitation of sugar, etc. with ether. $ 59. Separation of Tannin.—Tannic acid, when present in solu- tion, together with bitter prineiples, ete., may frequently be removed by digesting the aqueous infusion with oxide or hydrate of lead. If salieine (cf. $ 167), for instance, is to be separated from tannin, the aqueous infusion may be mixed with oxide of lead, evaporated to dryness on the water-bath and extracted with alcohol. Basic acetate oflead may also be occasionally used, when a bitter principle is to be separated from tannin, vegetable acids, albuminous matter and the like. Of course, it must have been previously ascertained that the bitter principle in question is not precipitated by lead; should that be the case, it may sometimes be isolated by decomposing the lead compound with sulphuretted hydrogen. By combining a bitter principle with lead a separa- tion may sometimes be effected from sugar, ete. This method is, however, inapplicable if tannie acid be present, when it will often be found advisable to precipitate vegetable acids, tannin, ete., by neutral acetate of lead before throwing down the bitter principle, etc., with the basie salt ($$ 51, 162). 8 60. Separation of Lead Precipitate —I£ such compounds of lead with bitter principles, glucosides, ete., are to be washed with water, it is very advisable to effect this as rapidly as possible by decantation. Such precipitates often block a filter, or form, by contraction, channels through which the wash-water runs off with- out penetrating the precipitate. If the use of a filter is neces- sary, repeated suspension in water and filtration is advisable. The washing of such precipitates should not be continued too long, as they usually undergo decomposition during the process and yield the bitter principle to the wash-water. The presence of carbonic acid in the water used for washing is specially to be avoided. Decomposition.—The decomposition of these preeipitates is usually effected by sulphuretted hydrogen, which, however, does 8 60, 61. @LUCOSIDES; RECOG@NITION. 53 not act well if the lead compound has been previously dried. It is a well-known fact that, in the course of this operation, the bitter prineiple may be mechanically retained by the sulphide of lead formed. To avoid loss in this way the sulphide may be filtered off, washed, dried, powdered, and boiled with alcohol. In evaporating the alcoholie extract care should be taken not to confound erystals of sulphur with the bitter principle, etc. It will often be found advantageous to decompose the lead preecipi- tate in alcohol instead of water. The surface-attraction of the sulphide of lead will, nevertheless, be frequently found useful in retaining foreign bodies, such as colouring matter and the like, whilst bitter principles, etc., pass into solution. The directions given for the decomposition of the lead precipi- tates may also be followed in isolating tannic and vegetable acids from such compounds. (See also $ 162.) 861. Glucosides; Recognition. —In proving the glucosidal nature of a substance advantage may be taken of the influence exercised by ferments (saliva, emulsin, myrosin), etc., or dilute acids (accom- panied by heat) on glucosides, which, under such eircumstances, split up and yield sugar as one of the products of decomposition. It is advisable to ascertain whether the substance itself, in as pure a state as possible, reduces an alkaline solution of copper, either at the ordinary temperature or on boiling. If no reduction takes place the further examination for glucose is much facilitated. It is customary to boil the substance under examination with water containing 1 to 2 per cent. of sulphuric or hydrochlorie acid, and test the liquid for sugar from time to time. The rapidity with which decomposition may be thus effected varies very greatly. Some glucosides yield a sugar reaction after boiling for a few minutes only ; others require several hours. In some cases it is preferable to allow the acid to act under pressure, or in alcoholic instead of aqueous solution. (Cf. 8 153, 160.) The decomposition-produets which are formed, together with glucose, from glucosides, are not unfrequently insoluble in water, and therefore render the liquid turbid in proportion as the re- action proceeds, This peculiarity may be often made use of as proof that decomposition has commenced, especially in those cases in which the glucoside itself reduces Fehling’s copper solu- tion. After the completion of the reaction and the cooling of the liquid, the decomposition-produet may be filtered off and further 54 SUBSTANCES SOLUBLE IN ALCOHOL. examined. If, on the other hand, this substance be soluble in water, its isolation may be attempted by tlıe method of agitation. An experiment should also be made to ascertain the action of the glucose thus produced on a ray of polarized light, as well as its behaviour with yeast—that is, its capability or incapability of entering into fermentation. For this purpose it is best to decom- pose the glucoside with sulphurie acid, which may be subsequently removed by carbonate of barium. The filtrate from the sulphate of barium, which should be faintly acid in reaction, should be mixed with a little yeast, introduced into a eudiometer over mercury, and observation made whether, under these eircum- stances, carbonic-acid gas is evolved. Many glucosides yield, besides glucose, products of decomposition which are antagonistic to alcoholie fermentation ; these are, if possible, to be removed. This fermentation experiment will have a particular value in all cases in which the glucoside itself reduces alkaline copper solution. Proof of the glucosidal nature of the substance may then be found in the experiment yielding a negative result before, but a positive one after, the action of the dilute acid, especially if the substance be soluble in ether or cold absolute alcohol. Saccharoses and other carbohydrates, which would yield similar results, are thus exeluded, they being insoluble in the liquids named. It is hardly necessary for me to point out the desirability of estimating, by means of Fehling’s copper solution, the sugar pro- duced by the decomposition of a glucoside. (Cf. $ 83, et seq. ; $ 200, et seq.) Some bodies which are usually treated of with the glucosides yield, when acted upon by acids, hot glucose, but substances allied to sugar or mannite, which, like isoduleite, are unfermentable. (C#. 8 212.) 862. Sulphuric Acid Group-reaction.—Many glucosides are capable of acting like sugar when mixed with bile and sulphurie add— that is, of produeing a red colour. This reaction has been described as to a certain extent characteristice of the whole group of gluco- sides ; but it should be remarked that among them there are many which are reddened by sulphuric acid alone, whilst some cannot replace sugar in the test for bile ; and others, when mixed with sulphuric acid, assume such characteristic colours that the bile reaction is quite undistinguishable. For further information concerning glucosides, compare $ 165, ei seq. ss 63. ISOLATION OF ALKALOIDS, ETC. 55 $ 63. Isolation of Alkaloids, ete., not Removable by Agitation.—As stated in $58, there are some alkaloids which, for the reasons there given, cannot be isolated by the method of agitation. To separate these in a state of purity the extraets prepared according to $ 57 should be exhausted as far as possible by shaking with petroleum spirit, ete., and then evaporated to dryness. The dry residue should be finely powdered (if necessary, with the addition of washed sand or siliceous earth) and treated with alcohol, ether, chloroform, etc. The exhaustion, however, with these solvents will be incomplete if the residue be not reduced to a very fine powder. (See also $$ 65, 66.) Detection by Group-reagents. —Before proceeding to this extrac- tion it may appear desirable to ascertain whether an alkaloid is present at all. To thatend the liquid obtained in $ 57, containing sulphurie acid but no alcohol, may be tested for alkaloids by preeipitants which have been introduced as group-reagents for that class of substances. The following may be especially recom- mended : Tri-iodide of potassium—that is, an aqueous solution of iodine in iodide of potassium—gives, with aqueous solutions of most alkaloids, amorphous precipitates of a dark-brown or kermes- mineral colour, and is one of the most delicate reagents. An alcoholic solution of an alkaloid frequently remains clear on the addition of the tri-iodide ; or if a preeipitate is formed, it differs in properties from that produced in aqueous solutions. For example, berberine and narceine would under these conditions yield erystalline precipitates. Tribromide of potassium, prepared in a similar manner, also pre- eipitates some of the alkaloids from very dilute solutions, but, in addition, forms yellowish compounds with phenol, orein, and many allied bodies ($ 158). Potassio-mercurie iodide, obtained by decomposing mercuric chloride with an excess of iodide of potassium, yields with most alkaloids, white, floceulent precipitates, which sometimes gradually assume a crystalline character. (Sce also 865.) The presence of free acid may sometimes cause a difference in the precipitate obtained from one and the same alkaloid. Potassio-bismuthie iodide, prepared by dissolving iodide of bis- muth and iodide of potassium in water, yields, even in highly dilute solutions, preeipitates which are very sparingly soluble, 56 SUBSTANCES SOLUBLE IN ALCOHOL. and resemble orange sulphide of antimony in colour. It should not, however, be forgotten that albuminous and other similar substances are also precipitated by this reagent. (Cf. $ 232.) Potassio-cadmic iodide, obtained in analogous manner from iodide of cadmium, gives white preeipitates, which, like those yielded by potassio-mercuric iodide, sometimes become crystalline. They are mostly rather more soluble than those produced with the latter reagent. Phospho-molybdie acid (a solution of the sodium salt. in nitrie acid) yields with most alkaloids yellowish preeipitates, which are in certain instances rapidly reduced, and assume a bluish or greenish colour. Ammoniacal salts and less complex amide- compounds are also precipitated by this reagent. Metatungstic acid gives similar precipitates ($ 177). Chloride of gold yields yellowish precipitates with very dilute solutions of many alkaloids. Sometimes a rapid reduction takes place, and the yellowish colour changes to a reddish-brown, the liquid itself occasionally assuming at the same time an intense reddish tint ($ 186). I consider this reagent especially valuable for our purpose, as ammoniacal salts and the less complex amides are not precipitated by it. Perchloride of platinum forms brownish-yellow preeipitates w ith most alkaloids (not all), but is less valuable than chloride of gold, because the precipitates are mostly more soluble, and because it forms sparingly soluble compounds with ammonium and potassium salts, ete. The precipitates obtained with this reagent also some- times show a disposition to decompose. Mercurie chloride.—The white precipitates which this salt yields with alkaloids are not very sparingly soluble, but it possesses some value, as it dloes not preeipitate ammoniacal salts, ete. The same is the case with Pieric acid, which gives yellowish precipitates. Tannic acid, the compounds with which are usually of a greyish- yellow or greyish-brown tint, and Bichromate of potash, which yields yellowish and occasionally erystalline salts.! 1 For group-reagents for alkaloids see further in my Ermittelung von Giften, 2nd edition, 123; also Selmi, Jahresb. f. Pharm. 1874, 480; 1875, 341; 1876, 628 (Year-book Pharm. 1876, 110). For behaviour of cinchona- alkaloids to sulphocyanide of potassium compare Schrage, Arch, d. Pharm. . $64. ALKALOIDS NOT ISOLATED BY AGITATION. 57 To confirm the presence of an alkaloid, advantage may also be taken of the fact that they all contain nitrogen, and, therefore, yield Prussian blue with Lassaigne’s test (heating with metallic sodium, ete.). This test will be specially valuable ıf another peculiarity of most, but not all, alkaloids—viz., the alkaline reaction towards litmus and capability of forming salts—be not well defined (colchieine), or if a compound be obtained which must be referred to the group of amido-acids (colchieine) or glucosidal alkaloids (solanine). It must not, however, be for- gotten that some of the glucosides already mentioned contain nitrogen ($ 167). For tables of the colour-reactions characteristic of many alkaloids see $ 171. . 864. Alkaloids not Isolated by the Method of Agitation ; Purifica- tion.—In cases in which an alkaloid is present that cannot be separated in this way or purified as recommended in $ 63, the following method may be tried. The alkaloid is preeipitated by potassio-mercuric iodide from its solution in water acidulated. with dilute sulphurie acid, the preeipitate filtered off, washed, sus- pended in water and decomposed by sulphuretted hydrogen. On filtering off the sulphide of mercury, a solution of the hydriodäte of the alkaloid together with free hydriodic acid is obtained. Sul- phate of silver is then added as long as it causes a precipitate, and the iodide of silver filtered of. After removing the sulphuric acid by addition of caustic baryta and filtration, a solution of the alkaloid may be obtained by freeing the filtrate from excess of baryta by carbonic-acid gas. The last separation of baryta, however, is not always quite complete. It might be better there- fore in many cases to remove the sulphurie acid by carbonate instead of hydrate of barium. The former, moreover, would be less likely to ddecompose the alkaloid. In following this method, inconvenience is occasionally experi- enced in filtering off the sulphide of mercury, which sometimes separates in a very finely-divided state. To obtain a clear filtrate, elxxiv. 143; [3], v. 504; xiii. 25; Hesse, ibid. xii. 313; xiii. 481; Godeffroy, Oesterr. Zeitschr. f. Pharm. 1878, Nos. 1 to 12 (Am. Journ. Pharm. 1878, 178). For the action of silico-tungstic acid on alkaloids see Godeffroy, Archiv d. Pharm. ix. 434 ; chloride of antimony and stannous chloride see Godeffroy, ibid. 147, and Smith, Jahresb,. f. Pharmacie, 1879, 166; arseno-molybdic acid, selenic and telluric acid, Brandt, Jahresb. f. Pharmacie, 1875, 341. Smith heats trichloride of antimony and projects the alkaloid into the fused mass. Morphine and codeine produce a greenish, narcotine olive- green, thebaine, brucine and veratrine, red colouration. 58 SUBSTANCES SOLUBLE IN ALCOHOL. evaporation with white bole and re-solution in water may be tried. The iodide of silver and sulphate of barium are also at times very diffieult to remove, and clear liquids can only be obtained by repeated filtration through double filters. Should the alkaloid, after liberation with caustic baryta, be sparingly soluble in water, it may be precipitated simultaneously with the sulphate of hbarium. In this case it may be extracted from the dry precipitate by treatment with alcohol or other suitable solvent. But those alkaloids that resist extraction by the method of agitation are generally freely soluble in water. Many alkaloids, too, are easily attacked by alkalies, splitting up, on boiling, into acids and new complex amides. Atropine under such eircumstances yields tropine and tropie acid ; hyoscyamine is resolved into the same two substances. (Öf. $ 65.) How easily errors are thus caused may be seen from the number of alkaloidal substances that have been described in text-books as special alkaloids, and which are in reality nothing but products of decom- position (acolyctine and napelline = aconine; ]ycoctonine = pseud- aconine).! Curarine is another alkaloid easily decomposed by alkalies. Certain members of this class are also decomposed by boiling with dilute acids. If the alkaloid under examination is not easily attacked by baryta or lime, it may be precipitated by phospho-molybdic or phos- pho-tungstic acid (8 63), and separated from its combination with either of these acids by baryta or lime, the excess of alkaline earth being removed by carbonic acid. "These methods, which are sometimes of use in the quantitative estimation of certain alkaloids, will be discussed in detail in $ 177. $ 65. Estimation.—For the quantitative determination of alka- loids, one of the following methods may be feasible : 1. The alkaloid obtained in $ 64 may be dried and weighed. 2, The substance removed by agitation according to $ 55, 56, may be weighed, care being taken to avoid loss.? 1 I avail myself of this opportunity to draw attention to the more recent researches of Wright and Luff on the aconite-alkaloids. See Jahresb. f. Pharm. 1873, 131; 1874, 135; 1876, 169; 1877, 434; 1879, 189; and in Pharm. Journ. and Trans. On atesin of Aconitum heterophyllum see Wasowiez, Archiv d. Pharm. xiv. 193 (1879) (Pharm. Journ. and Trans. [3], x. 310). See papers by Wright and Luff, ete., in Pharm. Journ, and Trans. [3], vols. ix. x. and xi. 2 Compare the methods I have proposed for the quantitative estimation of trychnine, brucine, and veratrine, in$ 174, Günther has successfully em- ! 865. ESTIMATION OF ALKALOIDS. 59 3, The alkaloid may be preeipitated from its aqueous solution by certain reagents, and estimated gravimetrically. Chloride of gold, or sometimes perchloride of platinum ($ 173), may be advantageously used as preeipitant in the last case, as the amount of alkaloid and chlorine present may be approximately caleulated from the amount of gold or platinum contained in the preeipitate. Alkaloids may often be estimated gravimetrically and volumetrically by preeipitation with potassio-mereuric iodide ($ 174). I have discussed this subject fully in my ‘Chemische Werth- bestimmung starkwirkender Droguen,’! where I have shown that many alkaloids may thus be accurately estimated. I found, how- ever, that the preeipitates produced were not always analogous in composition, and that therefore the precipitating power or value of the unit-quantity of reagent must be determined for each single alkaloid. The composition of the precipitate yielded by one and the same alkaloid may vary with the concentration of the solution, and a difference in the amount of sulphurice acid present may sometimes influence the result. A large excess of acid is incom- patible with the accurate estimation of certain alkaloids, such as brucine and coniine, whilst in other cases (nicotine, colchicine) it is necessary. The latter alkaloid, together with atropine and others, requires a considerable excess of the reagent for complete preeipitation, and in its gravimetric estimation therefore this condition must obtain; on the other hand, the precipitate first produced is sometimes redissolved on the addition of an excess of the preecipitant. With regard to the reagent itself, I may observe that, according to Mayer, it is not advisable to prepare it by dissolving iodide of mercury in iodide of potassium, the best method being to mix 13'546 gram of perchloride of mercury with 49:8 gram of iodide of potassium and water to make one litre. For details of experiments I refer to the work already men- ployed the method of agitation for the estimation of atropine. Compare Pharm. Zeitschr. f. Russland, 1869, p- 89 (Year-book Pharm. 1872, 236). In eolchicum also it would be more advisable to determine the alkaloid by shaking with chloroform than by precipitating with potassio-mercuric iodide. The material should be extracted with pure water, and the solution made acid rather than alkaline before shaking with chloroform. ' St. Petersburg, 1874. Schmitzdorft. 60 SUBSTANCES SOLUBLE IN ALCOHOL. tioned, and will only remark here that, as a rule, the material may be extracted with water acidulated with sulphuric acid, and that in many cases the estimation may be made in this liquid without further treatment. But if the presence of mucilaginous substances, etc., prevent this, and their partial removal by alcohol be necessary, the solution must be completely freed from spirit before titrating. The termination of the reaction is usually found by a drop of the filtered solution yielding no precipitate with a drop of the reagent. Aconitine and Nepaline—1 ce. of potassio-mereurie iodide solution of the above strength indicates 0'0269 gram of aconitine, and the precipitate (if the estimation be made gravimetrically) has the composition C,,H,,NO,1,+Hgl,.! In the latter case a correction of 0:00005 gram of aconitine must be made for every cc. of solution. 1 cc. of potassio-mereuric iodide indicates 0:0388 gram nepaline (pseudaconitine). Atropine.—1 ce. is equivalent to 0:0097 gram atropine if the solution contain about 1 in 200, but in solutions containing 1 in 330 it is equivalent to only 0'00829 gram. The preci- pitate obtained by adding an excess of the precipitant to a solution containing about 1 in 200 to 300 has the composition (C,H,NO,ID),+Hgl,. In working with solutions containing 1 in about 350 to 500 a correction must be made of 0°00005 gram of atropine for every ce. of filtrate ($ 174). Hryoscyamine.—1 cc. of the mercury solution is equivalent to 0:00698 gram hyoscyamine, the concentration being about lin 200. According to the more recent researches of Ladenburg henbane contains two alkaloids, one of which is isomerie with atropine, and identical with daturine and duboisine. Compare Berichte d. d. chem. Ges. xiil. 909, 1081, 1340, 1549 (Pharm. Journ. and Trans., [3], x. 759, 789, 790). [Ladenburg distin- guishes hyoscyamine from atropine by the melting-points of the alkaloids and their gold salts. In belladonna a second alkaloid at least is present, which is possibly identical with hyoscyamine.? The second alkaloid in henbane has been named hyoscine by Ladenburg, This must not, however, be confounded with 1 For the present I make use of the old formula for aconitine, as the new does not agree so well with the volumetrice determinations,. 2 Compare Kraut, Ber. d. d. cheın. Ges. xiii, 165. 865. ESTIMATION OF ALKALOIDS. 61 the hyoscine of Höhn and others. Its gold salt melts at a higher temperature than that of atropine or hyoseyamine.] (See further in $ 174.) 3. Emstine—1l ce. of the potassio-mereuric iodide precipitates 0:0189 gram emetine The precipitate has the composition C„H3N;0,I,+Hgl,! Coniine —1 ce. indicates 0°0125 gram. coniine provided that the solution contain 4 to 1 per cent. of the alkaloid, as little free acid as possible, and, in addition, 3 to 4 per cent. of chloride of potassium. If these conditions are complied with the composition of the pre- cipitate will be (C,H, ,NT), + Hgl, ($$ 174, 180). Nicotine.—1 cc. indicates 0:00405 gram nicotine; the composi- tion of the precipitate is C,H,N.L, + Hgl.. Strychnine and Brucine.—1 ce. precipitates 00167 gram strych- nine and 0'0197 gram’ anhydrous brucine (in the latter case as little free acid as possible should be present. The pre- cipitates have the composition C,„H,„N,O,HI+Hgl, and C,H,N,0,HI+ Hgl, ($$ 174, 180). Oolehicine. —1 ce. precipitates 00317 gram colchieine, the con- centration being about 1 to 600, and the solution containing 7 to 10 per cent. of sulphurie acid. The precipitate appears to contain four equivalents of colchieine to one of Hgl,. Morphine and Narcotine.—1 ce. corresponds to 0:02 gram erys- tallized morphine? and 0:0213 gram narcotine. (See also $ 174.) Veratrine, sabadilline, and sabatrine—1 ee. indicates, according to Masing,? 0:0296 gram veratrine. Little sulphurie acid only should be present and a correction of 0000068 gram veratrine made for every ce. of liquid. According to the same chemist, l cc. of the potassio-mereurie iodide is equivalent to 0:0374 gram sabadilline and 0:03327 gram sabatrine. Correction for every cc. 0:00005 gram of the former and 00000408 gram of the latter ($ 174). Physostigmine.—1 ce. preeipitates 001375 gram physostigmine (Masing). Correction for every cc. 0'000105 gram. The com- positiön of the precipitate is assumed to be C,H, N,0,HI+HgT,. (See also $ 174.) ! This formula, also, will have to be altered as soon as analyses of the pure emetine prepared by Podwissotzki are published. - * Forthe application of potassio-cadmic iodide to the quantitative determina- tion of opium alkaloids see Lepage, Repert. f. Pharm. 1875, 613, 3 Archiv d. Pharm. ix. 310 (Journ. Chem. Soc, xxxii. 369). 62 SUBSTANCES SOLUBLE IN ALCOHOL. Berberine—1 cc. indicates 0'0425 gram berberine (Beach).! The preeipitate is stated to contain almost exactly half its weight of pure berberine. Quinine—According to Prescott? the double salt of quinine with iodide of mercury contains 34°5 per cent. of alkaloid, and is almost insoluble in water. From the recent researches of Hielbig? it would appear that no special advantage is to be looked for in the application of potassio-mereuric iodide to the quantitative estimation of quinine. Chelidonine and Sangwinarine —From some experiments made by Masing I anticipate that 1 cc. of potassio-mereurie iodide will be found to indicate 001675 gram of the former and 001485 gram of the latter* (Compare also $ 174 et seq.) 8 66. Estimation of Theine, etc. —The quantitative determination of some alkaloids may be made as follows : The material is boiled with water, either pure or containing a little sulphuric acid, the filtered or strained decoction evaporated with magnesia or-lime,’ and the residue finely powdered with sand or some other inert substance. It is then extracted with ether, chloroform, or other suitable solvent, the filtered solution evaporated and the residue weighed.° I have found this method well adapted for estimating the alkaloid in tea (without the addition of acid). Similar methods have also been proposed for the estimation of the total alkaloid in einchona-bark, but the long-continued action of the dilute acid necessary to dissolve the alkaloid appears to decompose part of itand renders the estimation inaceurate. (Com- pare $ 176.) 8 67. Extraction of Cinchona Alkaloids.—In a series of experi- ments in my laboratory the following method was found by Hielbig’ to be the most advantageous: 25 grams of powdered bark are digested with 100 grams of 1 per cent. sulphurie acid at the ordinary temperature for twenty-four hours, care being taken to ex- 1 American Journ. Pharm, xlviii. 386. 2 Ibid. xlix. 482. 3 Kritische Beurtheilung, ete. Diss. Dorpat. *Compare my Chemische Werthbestimmung, p. 101. Also Naschold, Journal f. prakt. Chem. evi. 385. 5 Compare Cazeneuve, Jahresb. f. Pharm. 1875, 342. 6 Compare also Lösch, Pharm. Zeitschr. f. Russland, xviii. 545, and my re- marks on his method, Jahresb. f. Pharm. 1879, 165 (Year-book Pharm. 1880, 60). 7 Loc. cit. $ 68, 69. ESTIMATION BY TITRATION. 63 clude direct sunlight ; 500 cc. of spirit are poured in, and after two hours 25 grams of slaked lime are added to the mixture. The whole is then macerated for two days, and finally boiled for half an hour on the water-bath. To the filtrate, together with 100 cc. of wash-aleohol, the results of two following extractions, each with 250 cc. of spirit and 100 cc. washings, are added. The mixture is neutralized with 25 drops of dilute sulphurie acid (1 to 7) or more if much einchonine is present. After stand- ing twenty-four hours the spirituous solution is filtered, and the alcohol recovered by distillation, the process being stopped as soon as the liquid becomes cloudy (about 200 ec.) ; 15 cc. of 3 per cent. sulphuric acid are then added, and the evaporation continued on the water-bath, carbonization being carefully avoided. The residue is treated with water, the resin filtered off and washed with a little dilute sulphuric acid. The alkaloid is then precipitated by carbonate of soda, and the whole evaporated on the water-bath to about 20 ce. After cooling, the resinous preci- pitate is filtered off, rubbed down to a powder in a mortar with water, retransferred to the filter, washed, dried, and weighed. From the filtrate and wash-water the alkaloid is extracted by chloroform, and the weight thus found added. For the separa- tion of the more important bark alkaloids from each other, see 88 183, 184. $ 68. Estimation by Titration.—I£ the alkaloid under examina- tion has a powerfully alkaline reaction, it may be separated by the method of agitation, or according to $$ 66, 67, and esti- mated by titration with „5 acid. A method of this kind has been proposed by Schlössing and others for the quantitative determination of nicotine in tobacco.! (See $$ 179, 180.) 8 69. Separation of two or more Alkaloids. —In the methods described for the estimation of alkaloids it was assumed that only one was present. But two or more may be met with in the same plant. In attempting their separation their behaviour to solvents should be ascertained. Ether, for instance, may be used to separate quinine from einchonine, narcotine from morphine, delphinine from delphinoidine. ! Annales de Chim. et de Phys. xix. 230 (Am. J. Pharm. xix. 68) ; also Wittstein and Brandt, Vierteljahresschrift f. prak. Pharm. xi. 351, and xii. 322; Liecke, Zeitschr. f. anal. Ckem. iv. 492; Kosutany, Anal. Best, einiger Bestandth. d, Tabakspflanze. Diss. Altenburg in Hungary, 1873. 64 SUBSTANCES SOLUBLE IN ALCOHOL. This method is not, however, always successful, and com- pounds of the alkaloids differing considerably in solubility, ete., must be looked for, applicable to the separation to be effected. Quinine may be separated from quinidine by precipitation with Rochelle salt, quinidine from cinchonine by iodide of sodium, ete. Use may also be made of the difference in equi- valent weights. (Compare the estimation of brucine in presence of strychnine in $ 174.) See also 88 180 to 183. EXAMINATION FOR GLUCOSES SOLUBLE IN ALCOHOL. $ 70. Detection and Estimation of Glucoses soluble in Alcohol.— Both glucoses and cane-sugars may be present in that part of the alcoholic extract ($ 48) which is soluble in water, but the amount can be but small, since the material is macerated at the ordinary temperature. It must, however, be taken into account, in order to avoid error. If the alcoholic extract contain no tannin or bitter substance, the agueous solution may be tested for glucose with Fehling’s solution ($ 83) without further treatment ; if found it may be determined quantitatively. Sugar may also be qualitatively tested for by adding to the liquid under examination first potash and then dilute solution of sulphate of copper, as long as the cuprie hydrate first formed is redissolved. Excess should be avoided. The liquid may now be divided into two portions, one of which may be warmed and the other allowed to stand in the cold in order to ascertain whether reduction takes place at the ordinary temperature, as well as on heating. If the glucose is accompanied by such substances as tannin, etc., the filtrate obtained after addition of acetate of lead in their quantitative estimation ($$ 49, 52), or after precipitation of a separate quantity with basic acetate, may be treated, together with the washings, with a slight excess of sulphuric acid, filtered, washed and made up to a known volume. The sugar may then be estimated quantitatively with Fehling’s solution. The result must be added to the amount found in the aqueous extract ($ 83). Part of the solution may be boiled for half an hour with 1 to 2 per cent. of sulphuric or hydrochlorie acid in a flask fitted with an upright condenser. If more sugar be found after such treat- ment, the difference is to be calculated as saccharose ($ 85). 8 71, 72. TREATMENT WITH WATER, ETC. 65 7, EXAMINATION OF SUBSTANGES SOLUBLE IN WATER. MUCILAGE, ACIDS, GLUCOSES, SACCHAROSES AND OTHER CARBOHYDRATES, ALBUMINOUS SUBSTANCES, ETC. $ 71. Treatment with Water.—The residue of the material after exhaustion with alcohol ($ 47) is dried at a temperature not above 40° C., and transferred to the vessel previously used, which should likewise be dried. Water is then added in the proportion of at least 10 cc. for every gram of original substance, and the whole frequently shaken during twenty-four hours. The liquid is now filtered off through the same filter that has already served for such operations, and the filtrate set aside for examination. The residue is washed by repeated maceration and filtration, the wash- ings being reserved for treatment as directed in $ 194. The in- soluble substance is not dried ($$ 92, 102, 105 et seq. ; 193 et seq.). $ 72. Total Solid Residue—10 cc. of the filtrate are evaporated in a tared platinum dish, dried at 110° and weighed. The resi- due is then incinerated and the ash deducted. It should be ascertained if the ash is rich in carbonic, sulphurie, or phosphoric acid, chlorine, lime, magnesia or potash ; and if large quantities of sulphurie or phosphoric acid are present they should be estimated ($ 82). If the filtrate contain much sugar, moisture may easily be re- tained by the residue. In such cases Serrurier! advises the addi- tion of } per cent. of alcohol before evaporation. It is claimed that the residue is then porous and easily dried. EXAMINATION OF MUCILAGINOUS SUBSTANGES, DEXTRIN AND ALLIED CARBOHYDRATES PRECIPITATED BY ALCOHOL. 3 73. Mucilaginous Substances.—10 to 20 cc. of the aqueous extract ($71) are mixed with two volumes of absolute alcohol, and 1 Zeitschr. f. anal. Chemie, x. 491, 66 SUBSTANCES SOLUBLE IN WATER. allowed to stand for twenty-four hours in a cool place in a well- closed vessel. The precipitate is collected on a tared filter, washed with 66 per cent. spirit, dried and weighed. Both filter and sub- stance are then incinerated and the ash weighed, that of the filter being deducted. If the preeipitate itself possess the characters of vegetable mucilage ($$ 195, 196) and contain not more than 5 per cent. of ash, it may be assumed the latter corresponds to the lime and potash usually found in such mucilages. But if the percentage of ash be larger, and it contain much carbonate of lime or potash, attention should be paid to the possible presence of salts of vegetable acids with these bases, such as acid tartrate of lime or potash, etc. ($ 74). That the preeipitate really contains vegetable mucilage may be proved by its dissolving in water to a mucilaginous liquid which does not reduce Fehling’s solution until after it has been boiled for some time with dilute hydrochlorie acid. Its concentrated solution is precipitated by basic acetate of lead. It is also occasionally precipitated by ferrie chloride and thickened by solution of borax or soluble silicate of soda. See also $$ 193 to 196. $ 74. Vegetable Albumen.—Incomplete solubility of the mucilage preeipitate would indicate the presence of albumen, but, by the method of examination adopted, the quantity will usually be so small that it may be neglected. (See also SS 92 et seg.; 95 ei seq.) If, however, Lassaigne’s test show that the precipitate contains much nitrogen, the results of the estimation of legumin and albumen, which will be subsequently made, must be deducted from the weight of mucilage, ete. If, on treating the mucilage precipitate with a little water, a diffieultly soluble erystalline sub- stance be observed, examination should be made for tartrate of lime or acid tartrate of potash, which, if present, should be estimated by precipitating with neutral acetate of lead and should be deducted from the weight of the mucilage. 8 75. Imulin. —l£ subterranean parts of plants belonging to Composit® or allied orders are under examination, they may, even though previously dried, yield a little inulin to water. After precipitation with aleohol it is not redissolved by water at the ordinary temperature, but is freely soluble when warmed to 56°. It is leevo-rotatory, is converted by treatment with dilute acid into levulose, and may be estimated by determining the 88 76, 77. DEXTRIN, ETC.—SAPONIN. 67 amount of sugar thus produced. The majority of the inulin is, however, left in the residue insoluble in water, from which it may be extracted as directed in $ 102. $ 76. Dextrin, etc. —The filtrate and wash-alcohol from the mucilage precipitate ($ 73) are evaporated as rapidly as possible, at a temperature of 70° to 80°, to a syrupy consistence and again precipitated with 4 volumes of absolute alcohol. Certain car- bohydrates soluble in dilute alcohol, such as dextrin, levulin, sinistrin and tritiein, are thus thrown down and should be filtered off as rapidly as possible. These carbohydrates may be distinguished from mucilage by their being more easily convertible into sugar and by their not being preeipitated by basic acetate of lead. Dextrin is dextro- rotatory in aqueous solution, and yields grape sugar on boiling with a dilute acid. Levulin, sinistrin, and tritiein yield levu- lose. The first of these three is optically inactive ; sinistrin and tritiein are laevo-rotatory (ap = — 32°456° and - 43°579° respec- tively). None of the four are coloured either blue or red by iodine.! Sinistrin and triticin are precipitated by caustic baryta from solution in 40 per cent. alcohol. Carboniec acid liberates the carbohydrate from the compound thus produced ($ 198). Quantitative Estimation (8 199, 201 to 204).—The carbo- hydrates mentioned in the preceding paragraph are best esti- mated by boiling with a dilute acid and determining the amount of sugar thus produced by titrating with Fehling’s solution. The barium precipitates of levulin, triticin and sinistrin may be treated directly with acid. If dextrin and glucose are present together, the results yielded by the estimation are as a rule somewhat too high, as a little sugar is precipitated with the dextrin. It should, however, be ascertained whether the dextrin-preeipi- tate contain much nitrogen, and, if this is the case, whether the amido-acids discussed in $$ 101 and 242 are present. EXAMINATION FOR SAPONIN AND ALLIED SUBSTANCES. $ 77. Extraction of Saponin.—I£ the precipitate obtained with alcohol in $ 76 is rapidly filtered off, the majority of the saponin 15 was formerly thought that dextrin was coloured red by iodine. This colouration was due to an impurity (soluble starch—erythrodextrin) contained in the dextrin examined. ) E) 68 SUBSTANCES SOLUBLE IN WATER. remains in solution, and is left behind on evaporating the alcoholic filtrate. It is soluble in hot 83 per cent. spirit and deposited again on cooling; but in absolute alcohol it is almost insoluble. Baryta-water precipitates it from aqueous solution ; after washing with saturated baryta-water the saponin may be liberated from the compound by carbonie acid gas; a few per cent. of baryta, however, always remain associated with the saponin thus obtained. It also forms an insoluble compound with basic acetate of lead. Its solutions have an unpleasant acrid taste, froth on shaking, emulsify oils, ete. On agitating with chloro- form it is taken up by that solvent and may be obtained in an amorphous condition by evaporating the chloroformic solution. (C£.8 55.) The residue, moistened with a few drops of concen- trated sulphurie acid and exposed to the air, gradually assumes a reddish or reddish-violet colouration. It is a glucoside, yielding sapogenin as a resinous decomposition product sparingly soluble in water. | $ 78. Quantitative Estimation.—Christophsohn! and Otten? have adopted the following two methods for the determination of saponin: A. 10 grams of the powdered substance are boiled three times in succession with distilled water, the decoctions strained (they filter very slowly), evaporated to a small bulk, preeipitated with alcohol and filtered. The precipitate is exhausted with boiling alcohol (83 per cent.), and the spirituous solution added to the filtrate. After recovering the alcohol by distillation the residue is dissolved in water, concentrated and precipitated with saturated baryta-water. The precipitate is collected on a tared filter, washed with saturated baryta-water till the washings are colourless and dried first at 100°, subsequently at 110°. After weighing it is ignited till the ash is white, the baryta estimated as carbonate in the usual way, calculated into oxide and deducted from the weight of the saponin-baryta, the difference being the weight of saponin from 10 grams of substance. For the seeds of Agrostemma githago the following modification must be adopted on account of the large amount of starch rendering the extraction with water very tedious. A weighed quantity of ground air-dry seeds are 1 Vergl. Unters. über das Saponin, etc.’ Diss. Dorpat, 1874, and Archiv d. Pharm. vi. 432, 481. 2 Histiol. Unters, der Sarsaparillen. Diss. Dorpat, 1876. | ss 78, 79, 80. SAPONIN; ORGANIC ACIDS. 69 exhausted by boiling with alcohol and filtering whilst hot, the alcohol being recovered from the filtrate by distillation. The residue is freed from fatty oil by ether, dissolved in water and the saponin in it precipitated with baryta as before. B. The saponin-baryta obtained by the previous method is dissolved in water with the aid of hydrochlorie acid and freed from baryta by the cautious addition of dilute sulphuric acid. The filtrate and washings from the sulphate of barium are boiled for an hour ; the sapogenin which has separated out is filtered off, washed, transferred together with the filter to a small flask and exhausted by boiling with 83 per cent. of alcohol. On evaporating the filtered alcoholie solution and drying at 110° the weight of the sapogenin is ascertained and may be calculated to saponin, 100 parts of the latter yielding on an average 35'8 parts of the former. Christophsohn obtained the following results in a series of comparative experiments with both methods. The seeds of Agrostemma githago were treated as directed in A. A. B. 1. Quillaja saponaria (bark) ... a BSOM 8:82 % Saponin. 2. Gypsophila struthium (root) 59 50, 4 3. » » » 1331 132 „ „» 4. Saponaria ofhcinalis (root) ... u are 5809, ;, Fr 5. Agrostemma githago (ripe seeds) ... 6'67 6251, ” In the various sarsaparillas Otten found, by method 4, from 1'21 to 343 per cent. of saponin. (See also $ 167.) $ 79. Digitonin, which is allied to saponin, may be distin- guished by its assuming a fine red colour when heated with dilute sulphuric or hydrochlorie acid. Like saponin, it is easily soluble in cold water, sparingly in cold absolute alcohol. (Cf. $$ 155, 167.) EXAMINATION FOR ACIDS, ETC. $ 80. Estimation of Total Organic Acids. —Part of the filtrate obtained in SS 73 and 76 is concentrated and, after complete dissipation of the alcohol, preeipitated with neutral acetate of lead, avoidingan excess. After standing from twenty-four to forty-eight hours the precipitate is filtered off and treated as directed in $ 49. The organic matter present is noted as organic acids and allied substunces. If the presence of tannic acid, which has escaped re- moval by the previous treatment with alcohol, is suspected, it 70 SUBSTANCES SOLUBLE IN WATER. should be estimated in a portion of the filtrate from $ 73 or $ 76, by preeipitation with acetate of copper (cf. $ 50), and de- ducted from the total organic acids. $ 81. Qualitatwe Separation.—lf the lead precipitate is at first amorphous, but becomes crystalline on standing, malic or fumarie acid! may be present. (See also $$ 214, 220, 221.) The acids thuspreecipitated may befurther qualitativelyexamined by suspending the moist precipitate obtained as directed in $ 80 in pure water and decomposing with sulphuretted hydrogen. The filtrate from the sulphide of lead is evaporated on the water-bath to a small bulk and, when the odour of sulphuretted hydrogen has disappeared, lime-water is added to the cooled liquid till the reaction is alkaline. If a precipitate is produced which dilute acetic acid fails to dissolve completely, oxalic acid is probably present? (See also $$ 214, 218, 219.) If, on the other hand, it is entirely soluble in acetic acid, a fresh portion should be tried with solution of chloride of ammonium. Zartrate of caleium ($ 217) dissolves, racemate ($ 218) does not. In the latter case care should be taken not to mistake phosphate for racemate of calcium. If lime-water has caused no precipitate in the cold the solution should be hboiled. Any turbidity that may now occur would indicate ciric acid. (8 215, 216, 218.) Aconitic acid is not thrown down by lime-water even on boiling, but it is characterized by the slight solubility of its acid ammonium salt in 50 per cent. alcohol. The liquid to be tested is divided‘ into two portions, one of which is neutralized with ammonia and added to the other. Any crystals of acid aconitate of ammonium which separate out should be washed with 50 per cent. alcohol. From this salt the acid may be isolated by adding a slight excess of sulphurie acid and shaking with ether. Its identity may be established by the ultimate analysis of the calcium, silver and ammonium salts. (See also $ 216.) I think it is very pr nik that the so-called Marattin is aconi- tate of caleium ($ 102). Sphaero-erystals of this substance were 1 For the solubility of malate of lead in warm dilute acetic acid, and the deposition of a erystalline salt on cooling, see Hartsen, Zeitschr. f. anal. Chemie, xiv. 373 (Journ. Chem. Soc. xxix. 375). 2 Oxalate of calcium ($$ 100, 219)often settles slowly and on filtration passes through the pores of the filter. Muck has shown (Zeitschr. f. anal. Chemie, ix. 451) that the preeipitate is much easier to manipulate if small quantities of aluminium salts are present. 8 81, 82. ORGANIC AND MINERAL ACIDS. 71 observed by Russow in the stems of species of Marattia which had been kept in alcohol. If the presence of an oxalate has been indicated by the action of acetic acid, the acid solution should be filtered off and super- saturated with lime-water, which would re-precipitate tartarie, eitric, racemic acid, ete. Citrie acid may be detected by boiling the filtrate. Citric and tartaric acids may be separated quantita- tively by Allen’s method.! The acids are dissolved in 20 volumes of spirit, and a concentrated solution of acetate of potassium added. After standing twelve hours the acid tartrate of potassium is collected and estimated either gravimetrically, or by titration with normal solution of soda. (See also $$ 214 et segq; 217 et seq.) $ 82. Vol. Estimation ; Mineral Acids ; Free and Combined Acid. —If only’ one of the non-volatile acids mentioned can be de- tected, the estimation made in $ 80 may be checked by decom- - posing the lead preeipitate from a known fraction of the aqueous extract with sulphuretted hydrogen, evaporating the filtrate and titrating the residue dissolved in water. But in this case the phosphoric and sulphuric acids previously estimated in $ 7 must be deducted ($ 214). Mineral acids may be tested for qualitatively by adding a drop of an alcoholie solution of methyl-violet. Mineral acids change the colour to bluish-green. The amount of free acid present in fruits, ete., may be estimated in the aqueous extract by titration with normal alkali. A similar determination may be made in the alcoholic extract ($ 47). Any excess of acid found in the first estimation over that in the second may generally be ascribed to the acid salts present. If an extract from a vegetable substance is to be specially examined for free tartaric acid in the presence of acid tartrates (of caleium and potassium), the liquid may be evaporated to a syrupy consistence and the tartarie acid extracted with ether or absolute alcohol.” The alcoholic or ethereal solution is evapo- rated, the residue dissolved in a little spirit and the tartaric acid separated by the addition of alcoholie solution of acetate of potassium.® 1 Zeitschr. f. anal. Chemie, xvi. 251 (Pharm. Journ. Trans. [3], vi. 6). 2 Of. Claus, Zeitschr. f. anal. Chemie, xvii. 314. ? See also Nessler, Zeitschr, f, anal. Chemie, xviii. 230 (Journ, Chem, Soc. xxxvi. 981), 72 SUBSTANCES SOLUBLE IN WATER. EXAMINATION FOR GLUCOSES, SACCHAROSES, ETC. $ 83. Glucose. —The alcoholic extract may, as mentioned in $ 70, contain a small amount of glucose which, if present, should be quantitatively estimated. But, as was there observed, the whole of the glucose is not usually removed by cold alcohol, and the remainder must be looked for in the aqueous extract. If no tannic acid or other substance that reduces Fehling’s solution is present, the glucose may be estimated in part of the aqueous extract in $ 71 by direct titration.! But if the glucose is ac- companied by other substances that also reduce the salt, these must be removed before the estimation can be made. They may be avoided by using the filtrate from the mucilage precipitate ($ 73), or from the dextrine group ($ 76); the alcohol must be removed by evaporation, the residue dissolved in water and made up to a known volume. (Of. 8 197.) If such substances as tannic acid, etc., have to be removed, it is best to precipitate a portion of the aqueous extract with basie acetate of lead and remove the excess of lead with sulphuric acid before determining the sugar. Instead of keeping the alkaline copper solution recommended by Fehling ready for use, I keep separate solutions of the three salts of which it is composed, viz., 34°639 grams of crystallized sulphate of copper, 173 grams of Rochelle salt, and 120 grams of caustic soda, each in a litre of water. 10.cc. of each of these solu- tions with 20 ce. of water represents 10 ce. of alkaline copper solu- tion diluted with 4 volumes of water as recommended by Fehling. Of the three solutions the sulphate of copper alone requires to be accurately measured. The titration is made as follows: the alkaline copper solution is brought to the boil in a white porcelain dish and the sugar solution (previously made up to a known volume) added from a burette until the blue colour has completely disappeared. 10ce. of copper solution indicate 0'05 gram grape-sugar. Should the final disappearance of the blue colour be concealed by dark colouring matter, ete., in the solution, a few drops may be rapidly 1 On the estimation of sugar with copper solution, see Fehling, Annalen d. Chem. u. Pharm. Ixxii. 106, evi. 75 (Pharm. Journ. Trans. [1], ix. 419); Graeger, N. Jahr. f. Pharm. xxix. 193; O. Schmidt, ib. 270; Stzedeler u. Krause, Annalen d. Chem. u. Pharm. Ixix. 94 ; Pellet, Journ. de Pharm. et de Chimie, 4te Serie, xxvii. 460 (Journ. Chem. Soc. xxxiv. 612). 8 83, 84. ESTIMATION OF GLUCOSE. 73 filtered off and tested for copper by the addition of acetic acid and ferrocyanide of potassium. But a slight reaction will generally be obtained as traces of copper remain in solution and the absence of any reddish-brown precipitate after the lapse of a few minutes must be taken as sufficient indication of the termina- tion of the reaction. It is well known that the sugar solution should be very dilute ; the best strength is about 4 per cent. If a preliminary experi- ment shows it to be more concentrated, it should be diluted to about this strength.! The estimation may also be made gravimetrically, by quickly filtering off the euprous oxide, washing with water, drying and converting into cuprie oxide. This method is advisable if, in titrating, the final reaction is obscured, or if the amount of sugar solution available is not sufficient to complete the reduction of the copper-salt taken. But it must be borne in mind that by drying the cuprous oxide on the filter and weighing incorrect results would, as Brunner? has shown, be obtained, since the alkaline copper solu- tion dissolves cellulose and the filter accordingly loses weight. It is better, therefore, to dissolve the cuprous oxide and deter- mine the copper by the usual methods, or to estimate the excess of copper in the filtrate.? 317 parts by weight of copper, 357 of cuprous oxide or 397 of cuprie oxide indicate 180 of glucose, 171 of saccharose or 162 of starch, ete. ($ 200). $ 84. Other Methods of Estimating Glucose. —Glucose may also be estimated by Knapp’s reagent,* which consists of 10 grams of 1 Soxhlet—Zeitschr. f. anal. Chemie, xviii. 348 (Pharm. Journ. Trans. [3] xi. 720)—has shown that the reducing power of the glucose varies with the con- centration of the solutions. In making estimations the sugar solution should therefore be of asnearly as possible the same strength as that used for standard- izing. According to Soxhlet the gravimetric estimation in presence of an excess of copper may be attended with considerable error. But Maercker has shown that satisfactory results may be obtained by this method also, if the same conditions are always observed. See also Ulbricht, Chem. Centralblatt, 1878, 392, 584. * Zeitschr, f. anal. Chemie, xi. 32 (Journ. Chem. Soc. xxv. 928). E Oompare also Weil, ib. 284 ; Mohr, ib. xii. 296 ; Jean, ib. 111 ; Lagrange, ib. xv. 111; Brücke, ib. 100; Maschke, ib. xvi. 495. (See ce Chem. Soc. xxv. 1121; zxvil. 292; xxxi. 805, ib. 116; xxxii. 930.) 4 Annal. d. an, u. Bann. cliv. 252 (Pharm. Journ. Trans. [3] i 301). See also Mertens, Zeitschr. f. anal. Chemie, xiii. 76; Brumme, ib. xvi. 121. Knapp’s reagent keeps considerably better than F ehling? Si 74 SUBSTANCES SOLUBLE IN WATER. mereuric cyanide and 100 cc. of caustic soda (sp. gr. 1'145) in a litre of water; 0‘4 gram of the eyanide=40 cc. of solution indi- cate 0'10 gram glucose. Knapp determines the end of the ex- periment by touching a drop of the solution on filter paper with a drop of sulphide of ammonium. An excess of mercury would produce a brown colour ($ 200). Instead of Knapp’s solution an alkaline solution of potassio- mercuric iodide may be employed for estimating glucose, as re- commended by Sachsse The sugar solution for this reagent may be prepared as directed in$83. "The reagent as first recommended by Sachsse! contained a large excess of alkali, which rendered the estimation of dextrose and levulose in the presence of saccharose inaccurate. Heinrich? therefore altered the composition by re- dueing the amount of alkali to a minimum, and directed that a litre should contain 15 grams of mercuric chloride, 25 of iodide of potassium and 10 of caustie potash, 40 cc. indicate 0:1342 gram glucose The titration is made in the same way as with Fehling’s solution, and the end of the experiment determined by testing a drop with stannous chloride, which should not throw down a grey precipitate, showing that no excess of mercury remains in solution. The presence of ammonium salts does not interfere with the reaction. Nessler’s reagent for ammonia has a composition similar to Heinrich’s modification of Sachsse’s solu- tion, but contains a far larger quantity of caustic alkali, which is necessary for the detection of ammonia ($ 97). The appearance of the final reaction is retarded if the solution contains but very small quantities of invert-sugar. It is advisable to make the mercurial solution of such strength that 5 ce. indicate 0:0168 gram of invert-sugar. Glucose may also be estimated gravimetrically by using an acid solution of a mercurie salt. "The reagent recommended contains in a litre 30 grams of mercuric oxide, 25 of concentrated acetic acid and 30 of chloride of sodium. On boiling with sugar the mercury is reduced and may be weighed as mercurous chloride.? 5'88 parts of calomel indicate 1 part of glucose. 1 Jahresb. f. Pharm. 1876, 375 (Journ. Chem. Soc. xxxii. 226). See also Strohmer u. Klauss, Chem. Centralblatt, 1877, 697, 713 (Journ. Chem, Soc. xxxiv. 246). 2 Chem. Centralblatt, 1878, 409 (Journ. Chem. Soc. xxxvi. 180). 3 Jahresb, f. Pharm., 1877, 340. SS 8587. INFLUENCE EXERTED BY SACCHAROSES. 75 The reagent is said to be without action on cane-sugar, glycerin, arabin and dextrin. 8 85.—Influence exerted by Saccharoses.—If the glucose in the liquid under examination is not accompanied by saccharose, or other carbohydrate not precipitable by alcohol, fairly accurate results may be obtained by the methods detailed in $$ 83, 84. But saccharoses influence the estimation by their presence to an appreciable extent, although they do not themselves, when pure, reduce Fehling’s or Sachsse’s solution. The same applies to the determination by fermentation ($ 204) ; saccharoses may be partially converted by the yeast into ferment- able glucose. It cannot be said that we are in a position to estimate with exactness in every case the proportion of glucose and saccharose in mixtures. Sometimes, it is true, the accuracy of the estimation ‚leaves little to be desired—as, for example, mixtures of dextrose or invert-sugar with cane-sugar. Solutions of such mixtures may be examined in the polariscope, in addition to being tested chemically. But many instances occur in which the necessary conditions do not obtain. (Cf. $$ 208, 209.) $ 86. Estimation in Presence of Saccharose.—In such cases the only method we can adopt is, first, to remove the carbohydrates preeipitable by alcohol ($$ 73, 76), estimate the glucose with Fehling’s solution, and then repeat the estimation after acidifying with 1 per cent. hydrochloric acid and boiling for 15 to 20 minutes (or several hours if the presence of mycose be suspected) in a flask provided with an upright condenser. If the two determinations yield fairly concordant results, it may be assumed that no saccha- rose is present ; on the other hand, any excess that the second may indicate over the first may be noted as “saccharose or allied carbohydrate’” The possibility of error must, however, be admitted ($ 207). S 87. Estimation of Saccharose alone. —If the solution contains a saccharose alone, with the exception of milk-sugar or maltose, it will not reduce Fehling at all. Although, therefore, no reduction may be observed, the inversion with acid should not on any account be omitted, as the solution may contain a saccharose. (Üf. $ 207.) According to Pillitz,! cane-sugar may be easily inverted by R Zeitschr. f. anal. Chemie, x. 456 (Journ. Chem. Soc. xxv. 329). See also Nico], ib. xiv. 177 (Journ. Chem. Soc. xxv. 329). 76 SUBSTANCES SOLUBLE IN WATER. heating a solution of 1 part in 12 or 13 of water with 1'5 to 2:0 parts per mille of sulphuric acid (specifie gravity 1'12), in sealed tubes, to 130° or 135°. The estimation of sugar by the fermenta- tion of such solutions is said to yield numbers that are rather too low. That is not the case with determinations by Fehling’s or Knapp’s method. I am, on the whole, more inclined to use hydrochlorie acid for inverting ; but if the acid is to be subsequently removed, I must acknowledge that sulphuric is to be preferred, as it is easily pre- cipitated by carbonate of barium. $ 88. .böttger's Test.—The above tests also suffice for the detec- tion of glucose and saccharose. Böttger’s bismuth test may be employed as confirmatory of the presence of the former. It consists in warming the liquid with a solution of carbonate of soda, to- gether with oxynitrate or hydrate of bismuth ; if sugar be present, grey suboxide of bismuth is formed. (See also $ 200.) 8 89. Distinctwe Characteristic.—The chief marks of distinetion between the various members of the glucose or of the saccharose group are to be found in the difference in cerystalline form, etec., and in the action on polarized light. In the cases here alluded to, use may sometimes be made of these characters, especially if the solution contains only one carbohydrate and no other substance that might influence the erystallization or optical activity. But these conditions are seldom fulfilled, and in the majority of cases we must, therefore, forego an exact identification of the particular glucose and saccharose present, unless we have a considerable quantity of the substance under examination at our disposal. (CE SS 205-207.) If we have command of a large quantity of material, it would be best to endeavour to effect the separation of the carbohydrates by treatment with different solvents, decolourization with animal charcoal and crystallization. The cerystallization of glucose is favoured by direct sunlight; the presence of a small quantity of a mineral (hydrochloric) acid may also prove advantageous. (See also $ 205-207.) $ 90. Soluble Modification of Arabie Acid. Albuminoids not Pre- cipitated, by Alcohol.—In almost every plant-analysis the sum-total of the separate estimations of the substances soluble in water (mucilage, ete.) will be found lower than the estimation of the total solids in solution. One or more substances must, therefore, gs 90, 91. SOLUBLE MODIFICATION OF ARABIC ACID. 77 generally be present that are soluble in water, not preeipitated by alcohol or neutral acetate of lead and have up to the present time eluded investigation. It might appear hazardous to make conjectures as to the nature of these substances, but Icannot help remarking that in some cases a substance seemed to me to be present which, after evaporation of its alcoholie or aqueous solu- tion, did not again dissolve completely in either of those liquids. It appeared to agree in some of its properties with that form of vegetable mucilage that is obtained by dialyzing acidified solutions of gum, ete., which sometimes remains in solution on the addition of alcohol. When I have met with a substance agreeing with mucilage in this peculiarity, I have spoken, it is true, of a ‘ soluble modification of arabic acid,’ but I have not omitted to place a query after it.! The further investigation of this substance is a desideratum for plant-analysis. But in thus assuming the presence of such an “arabie acid,’ account must be taken of the results of the nitrogen determina- tions to be described in $ 96. By deducting the nitrogen in the residue of the material after extraction with water from that in the original substance, the amount in the substances soluble in water is ascertained. If, now, the amount of nitrogen present as albuminoids, nitric acid, ammonia and alkaloid is caleulated from the separate determinations and found to be much smaller than the estimation by difference, it should be remembered that under certain conditions water may dissolve albuminoids which alcohol fails to precipitate. 891. Mannmite.—Another substance, however, which is of not unfrequent occurrence in the vegetable kingdom, would similarly elude detection bythe foregoing experimentswith the alcoholic and aqueous extracts, as it is almost insoluble in cold absolute alcohol but is not preeipitated from its aqueous solution by the addition of either spirit or lead salts. The substance referred to is mannite. I£ present it would be included in the deficit mentioned in $ 90, but would be easy of detection, as it crystallizes with great facility in long prisms and needles and is somewhat sparingly soluble in cold spirit. It may be approximately estimated by preeipitating the aqueous solution with alcohol and basic acetate of lead, 1 Compare ıny ‘Chem. Beiträge z. Pomologie,’ Dorpat, 1878 ; Verlag d. Dor- pater Naturforscher Gesellsch. ; and Pfeil, ‘Chem. Beiträge z. Pomologie,’ Diss, Dorpat, 1830, 78 SUBSTANCES SOLUBLE IN WATER. removing the lead by sulphuretted hydrogen and any glucose that may be present by rapid fermentation. The residue may be exhausted with boiling 90 per cent. alcohol and allowed to erystal- lize inthe cold. But an aceurate result cannot be expected, since, in addition to other errors, mannite may be produced in consider- able quantity by the fermentation of cane-sugar.! For particulars of some substances allied to mannite see $ 212. The method of examination for bitter prineiples, glucosides, and alkaloids has been described in $ 58 to 69. (See also $$ 165 et seq. ; 171.) EXAMINATION FOR ALBUMINOIDS SOLUBLE IN WATER, AMMONIACAL SALTS AND NITRIC ACID. $ 92. Extraction of Albuminoids.—It has already been observed in $74 that if the residue, after extraction with ether and alcohol, be exhausted with water the estimation of albuminoids in the aqueous extract thus prepared will generally give inaccurate results. A fresh portion of material should therefore be directly exhausted with water, or, if much fixed oil is present, the extrac- tion with water may be preceded by treatment with petroleum spirit. After having removed the fixed oil (if necessary) from about 10 grams, the residue is dried at 40° C., macerated with 100 cc. of water, with frequent agitation, for 4 to 6 hours, and filtered as described in $71. IJ£ thought desirable the maceration may be conducted at a temperature not exceeding 35° to 40°, (Compare also $ 225 et seq.) Detection.—With a portion of the filtrate qualitative experi- ments should be made. Among the reagents used for the detec- tion of albumen, iodine and merecuric nitrate (containing as little free nitric acid as possible) may be mentioned ; the former colours it brown, whilst the latter produces a yellow colour, changing, on the addition of a trace of nitrous acid, to a splendid red. The. addition of caustic potash to albumen, previously moistened with solution of sulphate of copper, is followed by the appearance of a. bluish-violet colour. If the amount of albumen present be rather small, these experiments may be made with the precipitates ob- tained by the addition of an acid to the aqueous solution ($ 93). Microchemical.— These reagents also serve for the microchemical. detection of albumen. The latter substance possesses, moreover, 1 Archiv d. Pharm. xv. 47 (Journ. Chem. Soc, xxxviii. 100). 88 92, 93, 94. ESTIMATION OF ALBUMEN. 19 the property of absorbing aniline-violet (protoplasm generally assuming a bluish-violet, the cell-nucleus a reddish tint), carmine, cochineal, piero-carmine, etc. Note should also be taken of the form in which the albumen oceurs, whether crystalline or amorphous, ete. (See also $$ 74, 90, 95, 194.) Protoplasm is coagulated by absolute alcohol and by glycerine. It becomes clear with solution of caustie potash, cloudy with acetic acid. Nuclei are generally stained more deeply than pro- toplasm by aniline-violet, ete., and by iodine. They are coloured deep blue by a solution of hematoxylin (1:30) and alum (1:10); the former alone also produces the same effect if the section has been previously treated with pierie acid and the excess of the latter completely removed (Schmitz). Crystalloids .dissolve in dilute potash, ammonia, and acetic acid. Precipitation.— Albuminous substances are precipitated by ferro- cyanide of potassium and acetic acid, by aqueous solution of trichloracetie acid, and by solution of xanthogenate of potassium. The preeipitate produced by the last reagent becomes flocculent on heating to 30° (Zöller). (See also 8 95, 231, 232.) _ 8 93. Estimation of Legumin and Globulin.—Part of the filtrate (25 to 50 cc.) is acidified with hydrochloric acid in the cold. By this means such substances as legumin are precipitated ; they should be collected on a tared filter, washed first with water acidified with hydrochlorie acid, then with 40 per cent. spirit, dried and weighed, deducting ash ($ 225 et seqg.). I£ hydrochlorie acid has caused a precipitate, a fresh portion of the filtrate should be tested for globulin by saturating with carbonic acid. It should also be ascertained microscopically whether the precipitate (if any) is crystalline or amorphous. (Uf. $$ 226, 227.) $ 94. Estimation of Albumen.—To the filtrate from the legumin (without the spirit-washings), 5 to 10 cc. of a concentrated solution of chloride of sodium are added, together with enough acetate of soda to remove all the hydrochlorie acid, and the whole raised to the boiling-point. If flocks of albumen separate they must be collected, washed first with boiling water, afterwards with 40 per cent. spirit, dried and weighed, deducting ash. In the absence of legumin 25 cc. of the aqueous extract may be mixed with 5 cc. of a concentrated solution of chloride of sodium and a few drops of acetic acid and treated as described in the foregoing paragraph. (See also $ 230.) 80 ‘ SUBSTANCES SOLUBLE IN WATER. $ 95. Estimation of Total Albumen. (a) Precipitation with Tannin.—Another portion (25 cc.) of the aqueous extract is mixed with half its volume of a concentrated solution of salt and a solution of tannin and acetic acid in dilute alcohol (20 grams tannin, 37°5 cc. glacial acetic acid, 400 cc. spirit made up to a litre with water) added as long as a preeipitate is produced. This is then rapidly filtered off, washed with water and dried. The albumen contained in it may be determined by estimating the nitrogen and multiplying by 6'25 (see $ 224), or by extracting the tannin from the powdered precipitate by boiling with alcohol, collecting and weighing the residue. (Cf. $ 229.) This estimation of albumen should be compared with the previous estimations of legumin ($ 93) and albumen ($ 94). If the determination by tannin yields a higher result, the difference may be taken to represent albuminous substances not preeipitated by hydrochloric acid or by boiling with acetic acid. (Compare also the remarks on peptone in $ 232.) As already observed in $ 5l, in working with substances con- taining a large quantity of tannin, the results obtained by pro- ceeding as directed in $$ 92, ei seg., cannot be quite accurate, as part of the albuminous matter is retained by the tannin in the residue insoluble in water. This undissolved albumen may be determined as directed in SS 96, 224. Amongst the substances which facilitate the solution of albumen we may include arabin. Günsberg! has proved that albumen, of animal origin at least, is precipitated by gum from slightly acid solutions, but redissolved by an excess. Dextrin is said to differ from gum in not redissolving the preeipitated albumen when added in excess. 8 96. Total Nitrogen.—It is advisable to determine the total nitrogen in the substance under examination before and after exhaustion with water ; the difference represents the nitrogen in the substances removed by that menstruum. If from this differ- ence the nitrogen contained in the albumen estimated according to 8 93 to 95 is deducted, the remainder will be nitrogen that has been dissolved by water in the form of ammoniacal salts, amides, alkaloids, nitrates, ete. The following estimations should be made with the object of determining as far as possible in what state this remaining nitrogen exists. 1 Journ. f. pract. Chem. Ixxxviii. 239, 897. ESTIMATION OF AMMONIA. 8l $ 97. Ammoma.—A portion of the aqueous extract ($ 92) is mixed with two volumes of alcohol and filtered. To the filtrate and washings calecined magnesia is added, and the ammonia distilled off into a receiver containing a measured quantity of normal sulphurie or hydrochlorie acid, every precaution being taken to avoid loss of ammonia and spirting of the magnesia mixture into the receiver. The apparatus I use is represented in Fig. 2. The flask 4 should not be more than half full of magnesia —- — zz N —— TG ee + =’. % 5 Fig. 2. mixture, and a plug of glass wool should be inserted in the neck. The small tube e contains glass beads, which are moistened with part of the acid. The distillation is complete when the vapours that issue on opening the clip b are free from alkaline reaction. The estimation may be completed in either of the two following ways: (@) The excess of acid in the receiver is determined volumetri- cally and deducted from the quantity taken. From the differ- 1 Compare also Morgen, Zeitschr, f. anal. Chem. xx. 37 (1881). 6 82 SUBSTANCES SOL ÜUBLE IN WATER. ence the amount of ammonia may be calculated in the usual way. (b) The ammonia may be distilled into hydrochlorie acid, the liquid evaporated to dryness, the residue alternately moistened and dried two or three times, and the chlorine estimated volu- metrically by nitrate of silver and chromate of potash. From the chlorine found the amount of ammonia may be calculated. Another method for the estimation of ammonia is that pro- posed by Schloessing. A few grams of the material made into a paste with water, or better, a concentrated aqueous extract, is mixed with milk of lime and placed over a measured quantity of volumetrie sulphuric acid under a belljar. The ammonia liberated by the lime is absorbed by the sulphurie acid, and after standing two or three days at a temperature as nearly constant as possible (8° to 10°), the amount of acid thus neutralized may be ascertained by estimating the excess with volumetric solution of soda, and from this the ammonia may be calculated. It must be admitted! that in all these experiments the action of the lime or magnesia on albuminous substances may result in the formation of ammonia. It is advisable, therefore, to remove such substances by precipitation with basic acetate of lead before distilling. Glutamine and asparagine, however, remain in solu- tion. These substances, when pure, are not acted upon by either lime or magnesia, but Schulze believes that they undergo a partial decomposition in mixtures, and therefore recommends boiling with hydrochlorie acid for one to two hours (compare remarks on asparagine, $ 191), by which they are completely resolved into the corresponding amido-acids and chloride of ammonium. The estimation of ammonia now includes the total ammonia derived from the asparagine and glutamine These two sub- stances may, however, be determined by Sachsse’s method, and the ammonia they yield caleulated and deducted. If the precautions mentioned have been observed, the first method (a) will generally yield satisfactory results. 8 98. Amido-Compounds, etc. — The foregoing estimation will be inaccurate if the material under examination contains amido-com- pounds, ete., or volatile alkaloids, as the former yield ammonia and the latter distil over and saturate part of the acid. Many amines, 1 Compare E. Schulze, Zeitschr. f. anal. Chem. xvii. 171 (1878) ; Journ. Chem. Soc. xxxiv. 308, 8 98. ESTIMATION OF AMIDO-COMPOUNDS, ETC. 83 etc., thus liberated, yield with perchloride of platinum double salts ($ 183) that are soluble in ether-aleohol, and error may therefore be frequently avoided by preeipitating a second portion of the distillate with excess of perchloride of platinum, evaporating on the water-bath, extracting the residue with ether-aleohol, drying and weighing instead of titrating the excess of acid with an alkalı. I£ both experiments yield the same result it may be concluded _ with tolerable certainty that no amides, or only traces, are present. If the estimation by the first method gives a higher result than that by the second, the former is to be regarded as the more accurate, and the excess noted as amido-compounds, ete. If, on the other hand, the estimation by platinum is higher than that by titration, the presence of an amide forming a double platinum salt insoluble in ether-aleohol and of a higher molecular weight than ammonia would be indieated. In the method of deter- mining ammonia described in $97, 5, certain chlorides of amines and alkaloidal substances, as for instance coniine and nicotine, would be almost completely volatilized, and thus escape esti- mation. The separation of ammonia from many amines may frequently be effected by taking advantage of the difference in solubility of the chlorides, sulphates, and oxalates of the respective bases in alcohol. In preparing larger quantities of the base for closer investigation, the material might be distilled with magnesia or lime (97 a), the distillate received in one of the above-mentioned acids, and evaporated to dryness on the water-bath. The residue might be extracted with alcohol, the solution again evaporated to dryness, and the distillation with alkali repeated, if possible, in a current of hydrogen. (Cf. $ 239.) $ 99. Nitrie Acid. —For the estimation of nitrie acid another portion of the aqueous extract of $71 is taken and treated by Schulze’s! or Wulfert’s? method. Schulze directs the liquid to be treated first with pure potash, as long as ammonia is evolved, then with permanganate of potassium (free from nitrate) till the colour is permanent after ten minutes’ boiling, Excess of permanganate is removed by formic acid, the solution neutralized with pure sulphuric acid and evaporated to about 10 ec. This is then introduced into the flask A of the 1 Zeitschr. f. anal. Chem. vii. 392. *? Landw. Versuchsstationen, xii. 164. 6—2 84 SUBSTANCES SOLUBLE IN WATER. apparatus recommended by Schulze! (Fig. 3), a weighed quantity of powdered aluminium added, and solution of caustie soda slowly run in; from the deficit in the amount of hydrogen yielded the nitrice acid present may be calculated. The following are the details of the operation : A measured quantity of solution of caustie soda is introduced into the pear-shaped flask D. The end of the glass-rod c is accurately ground into the delivery-tube of DB, so that no soda can escape into A until the rod c is raised. The tube C is 1 Zeitschr. f. anal. Chem. ii. 379, and vi. 379. 88 99, 100. ESTIMATION OF NITRIC ACID. 85 graduated, and communicates with D by means of an indiarubber tube. Both C and D are filled with water till the zero in C is reached, the water standing at the same height in D. The solution of soda is then allowed to flow slowly into 4 (which already con- tains the liquid and powdered aluminium), so that the experiment may last from two to three hours. 'The hydrogen evolved causes a rise of the water in D, but by occasionally opening the clip at g, it may be maintained at about the same level in both tubes. Care must be taken at the end of the experiment that the level is exactly the same before the final reading is taken. From the volume of gas thus found the volume of the caustic soda introduced from B must ve deducted, and the remainder corrected for temperature, N NN N IRQ N N IN pressure, and tension of water-vapour. A previous blank experi- ment having shown the amount of hydrogen obtainable from the aluminium taken, the nitrie acid may be calculated from the deficit, 4 molecules of hydrogen corresponding to 1 of nitrie acid or nitrate of potassium. $ 100. Wulfert’s method is a modification of Schloessing’s devised by Schulze: 0:5 to 1:0 gram of the pöwdered substance is, boiled with water to which a little milk of lime has been added, filtered and washed ; the filtrate and washings are then evaporated to 30 or 40 cc., and again filtered. The filtrate is neutralized with hydrochlorie acid and introduced into the flask A (Fig. 4), the neck of which has been drawn out so as to admit of connection 86 | SUBSTANCES SOLUBLE IN WATER. by means of an indiarubber tube with the bent glass tubea. The longer leg of the latter is similarly conneeted with a second bent- glass tube c, communication being regulated by a clipatd. The clip being opened, the atmospheric air in the flask is completely expelled by boiling the liquid down to at least one-fourth of its original bulk. The end of the glass tube c is then introduced into a precipitating glass containing about 30 ce. of a concentrated solution of ferrous chloride, and, after allowing a little steam to escape, the clip at b is closed and the lamp removed. As soon as a partial vacuum has been produced in A, the clip is cautiously opened, and about 20 ce. of the iron solution allowed to enter. The preeipitating glass is then filled with hydrochlorie acid. (sp. gr. 1:12), and 25 to 40 ce. introduced in a similar manner, so as to sweep the iron solution out of the tubes into the flask. After elosing the end of the tube c with an indiarubber stopper, it is introduced into a mercury-bath and brought under a cylinder 2, previously filled with mercury. The stopper is now removed, and the flask again heated until the pressure in the interior is nearly equal to that of the atmosphere. By opening the clip b, and regulating the pressure with the finger and thumb, the mercury is allowed to rise in the tube so as to drive most of the hydrochlorie acid into the flask ; it must, however, itself be carefully prevented from passing into the latter. After the external pressure has been overcome, the heat is so regulated that half the liquid in the flask distils over in eight to ten minutes. It is then certain that all the nitrie oxide that has been formed has been driven into B. The latter is provided with a glass-tap d, and can be connected air-tight with a measuring tube f. After cooling, the measuring tube filled with mercury is fitted on to the eylinder, and the nitrie oxide transferred to it by opening the tap and sinking the cylinder. The amount of nitrie acid may then be calculated from the volume of nitrie oxide found.! $ 101. Sclerotie, Cathartic Acid, etc. —lIf the total amount of nitrogen in the aqueous extract ($ 96) is now found, on com- parison, to be larger than that present as albuminoids, alkaloids, ammonia and nitrates already estimated, the excess may be reasonably ascribed to certain albuminous substances not pre- 1 On the estimation of nitrie acid in cultivated plants, see also Schloessing, Journ. f. pract. Chem. lii. 142; Frühling und Grouven, Landwirthsch. Versuchsst. ix. 9, and 150 (1867) ; Reichardt, Zeitschr. f. anal. Chem. ix. 24 (1370) (Journ. Chem. Soc. xxiv. 439). Ze TE 102. EXAMEN ATION FOR INULIN. 87 cipitated in $$ 93, 94, or certain amido-acids, such as sclerotic or cathartic acid, ete. (For the latter see $ 242.) EXAMINATION FOR INULIN. $ 102. Extraction and Estimation.—It has already been mentioned in$ 75 that in dried drugs the majority of this carbohydrate is present in the form of an insoluble modification ; in fresh it is always dissolved in the cell-sap. Dried drugs may accordingly be treated first with cold water as directed in $ 71, 92, and the residue digested for some time with water at 55° to 60° (not higher). At this temperature inulin passes into solution. From a measured volume of the aqueous extract it may be preeipitated by the addition of three volumes of alcohol; and if for every 100 ce. of mother liquor a correetion of 0'l gram of inulin is made, it may be thus estimated with tolerable accuracy.! Characters. —Inulin is not preeipitated in a gelatinous or curdy form, but in a pulverulent condition. It has already been ob- served that an aqueous solution is leevo-rotatory, and that boiling with a dilute acid converts it into lavo-rotatory fruit-sugar (levulose). Inulin may be satisfactorily estimated by converting it into levulose and titrating with Fehling’s solution. Of course, the above mentioned correction must be made. I should not, however, proceed to the extraetion with water at 55° to 60° unless a preliminary experiment had indicated the pro- bable presence of inulin. Microscopical.—In dried drugs inulin usually appears, under the microscope, in the form of agglomerated masses in the parenchy- matous cells. If fresh parts of plants that contain inulin are allowed to stand for several days in strong spirit, it is deposited in very characteristic sphsero-erystals, which dissolve in acid and alkali without swelling. Inuloid, which is said to occur in spring in the rhizomes of plants of the natural order Composite, may also form similar sph&ro-erystals, as do also marattin and a substance found in Acetabularia mediterranea which has not yet been closely investi- gated. (Cf. $ 81.) Inuloid is said to be distinguished from inulin by its somewhat greater solubility in water.? ! Compare my ‘Materialien zu einer Monographie des Inulins.’ St. Peters- burg, 1870. ® Compare Annal. d. Chem. u. Pharm. clvi. 190. 88 SUBSTANCES SOLUBLE IN DILUTE: SODA. vu EXAMINATION OF SUBSTANCES SOLUBLE IN DILUTE CAUSTIC SODA ; METARABIC ACID, ALBUMINOUS SUBSTANCES, PHLOBA- PHENES, ETC. $ 103. Extraction.—The residue insoluble in water ($ 71) is sus- pended, whilst still moist, in water containing a known quantity (about 0:1 to 0'2 per cent.)! of caustic soda in solution, using about 10 cc. of alkaline liquid for every gram of original substance. After standing for about twenty-four hours, with frequent agitation, the mixture is filtered. From 20 cc. to 50 cc. of the filtrate are acidified with acetic acid, mixed with 3 volumes of 90 per cent. alcohol, and allowed to stand for twenty-four hours in a cool place. The precipitate is then collected on a tared filter, washed with 75 per cent. alcohol, dried, and weighed, de- (ducting ash. This preeipitate usually consists of mucilaginous substances (pectin) and albuminoids. The former generally cor- responds to Scheibler’s metarabic acid ($ 195). $ 104. Detection and Estimation of Albumen.—lt Lassaiene’ s test shows the presence of a considerable quantity of albuminous sub- stances, these should be estimated and deducted. To this end another portion of the filtrate is precipitated as in $ 103, the nitrogen in the precipitate estimated and calculated into albu- minoids ($ 224). This amount is then deducted from the weight of the precipitate in $ 103. (See also $$ 226 et seqg,; 236 to 238.) $ 105. Estimation.—But the amount of albuminous substances in- soluble in water thus found cannot be noted as such in the summary of results unless it corresponds to that caleulated from the nitrogen in the residue insoluble in water, as directed in$96. I£ the latter is lower, it is to be regarded as the more accurate of the two ; the 1 Not more, otherwise starch is attacked. ALBUMINOIDS NOT DISSOLVED BY DILUTE S0DA. 89 explanation of this is to be found in the fact alluded to in 5 92 ed seq., Viz., that the material treated according to $ 103 has been ex- hausted with ether and aleohol previous to being extracted with water, and that therefore the quantity of albuminoids taken into solution is smaller than that extracted according to $ 92. But since the soluble albuminoids are determined in material that has not been subjeeted to the action of ether, ete., it follows that the nitrogen in the residue after exhaustion with water should guide us in estimating the insoluble albuminoids. It should be observed that one extraction with dilute caustic soda is often insufficient to remove all the substances soluble in that menstruum. The treatment should therefore be repeated a second and, if necessary, third time. $ 106. Albuminoids not Dissolved by Dilute Soda—There still remains the question whether the assumption is admissible that all albuminoids insoluble in water are dissolved by the dilute caustic soda used in $ 103. I can only reply that in a large number of experiments made by Stackmann, Koroll, and Cramer- Dolmatoff,! the residue after extraction with water, alcohol, and soda was always tested for nitrogen, with the result that in none but substances very rich in suberin could it be said that & little was often present. Of course, it would be possible to apply Lassaigne’s test to the residue after extraction with dilute soda; if evidence of nitrogen be obtained, the amount should be estimated and calculated as “ albuminoids insoluble in dilute soda.” In experiments made by Trefiner? on mosses in my laboratory it was found that the amount might occasionally be very considerable. At all events, if nitrogen is present, the quantity should be determined. (Cf. $$ 232, 238.) $ 107. Substances Dissolved by Dilute Soda, not Precipitated by d lcohol.—The filtrate and washings from the precipitate obtained in $ 103 are evaporated to dryness, and the calculated amount of acetate of soda deducted from the dried residue. (See $ 237.) The remainder represents the substances soluble in dilute caustie soda, not precipitated by acetic acid and alcohol. If the residue dissolves completely in a few ce. of water it may be concluded that no substance allied to phlobaphene, soluble in alcohol, is present. In that case the organic matter (apart from the acetate 1 See the dissertations, ete., subsequently quoted, ® Dissertation. Dorpat, 1881. 90 SUBSTANCES SOLUBLE IN DILUTE SODA. of soda) is sometimes a decomposition product of metarabie acid or of allied mucilaginous substances. The action of caustic soda on the latter often results in the formation of products that are not pre- cipitable by alcohol. But this body that thus remains in solution on adding alcohol will be more often found to belong to the albuminoids. (See $ 235.) $ 108. Phlobaphene.—A. brown residue insoluble in water would frequently consist of phlobaphene. (See also $ 48.) It should be collected on a tared filter, washed, dried, weighed, and deducted from the evaporation-residue in $ 106 before the weight of the substances derived from mucilage, caseine, etc., can be arrived at. (See also $ 246.) The polyporie acid, isolated by Stahlschmidt,! may also be mentioned here. It is insoluble in water, ether, benzene, bisul- phide of carbon, and glacial acetic acid, sparingly soluble in warm chloroform, alcohol, and amylie alcohol, but dissolved by dilute ammonia, forming a violet liquid, from which it is precipitated by hydrochloric acid.. It erystallizes in rhombic plates, and melts at about 300°. ‘ Humus’—I am convinced that the “humus’ mentioned in old plant-analyses was in reality partly phlobaphene and its decom- position-products. In the majority of vegetable substances humus is not to be found, unless they are already in a state of decomposition. Perhaps some thick barks and lignified fungi might yield substances with characters resembling those possessed by humus. To solvents such substances would, it is true, show a behaviour similar to that of the phlobaphenes ; but in distinguish- ing them we may take advantage of the fact that the majority of the so-called humie substances contain hydrogen and oxygen in the proportion in which they exist in water, and that humus does not yield the decomposition-products mentioned in $ 42 when acted upon by fused caustic potash. j 1 Annal. d. Chem. und Pharm. celxxxvii. 177 (1877) (Journ. Chem. Soc. xxxii. 620). 88 109, 110. EXTRACTION WITH DILUTE ACID. 91 LIE EXAMINATION OF SUBSTANCES SOLUBLE IN DILUTE HYDROo- CHLORIC ACID ; PARARABIN, OXALATE OF CALCIUM, ETC., AND STARCH. $ 109. Method of Extraction.— The insoluble residue from $ 103 is washed with water (which is best accomplished either by de- cantation or as directed in $ 71), and suspended in water con- taining 1 per cent. of hydrochlorie acid. Itisadvisable to adhere to the same proportion of menstruum to material as already recommended. The method of procedure now depends mainly upon the presence or absence of starch and of pararabin (or allied substance). "The former may be recognised under the microscope by the blue colour the granules assume when treated with an aqueous solution of iodine.! $ 110. Estimation of Oxalate of Calcium.—The simplest case would be that in which neither starch nor pararabin is present. The only object in digesting with dilute hydrochlorie acid would then be to extract oxalate of calcium. To effect this the digestion should be continued for about twenty-four hours at a temperature of 30°. A measured quantity of the filtrate may be neutralized with ammonia, or mixed with aknown quantity of acetate of soda sufficient to convert all the hydrochlorie acid into chloride of sodium. The oxalate of caleium, which. separates out insoluble 1 If large quantities of mucilaginous (? albuminous) substances are present, this colouration is not perceptible on directly moistening a transverse section with iodine water. The mucilage (or albumen) must be first removed by treat- ment with a dilute (0'1 per cent) solution of caustic soda. A stronger solution should not be employed, as it might act upon the starch itself. If the residue from $ 103 is examined, the treatment with alkali is of course unneces- sary. For a classification of starches, according to the shape of the granule, see Nägeli’s ‘Monographie der Stärkekörner,’ Basel, 1858 ; and Vogl, Zeitschr. d. österr. Apoth. Ver. 1866, pp. 290, 310. 9% SUBSTANCES SOLUBLE IN DILUTE ACID. in acetic acid, is allowed to settle, and when the supernatant liquid is perfectly clear it is poured off, and the precipitate transferred to a fine filter, washed and dried. It may then be converted either into carbonate by gentle, or into oxide by strong ignition, and from the weight of either the amount of oxalate calculated. The filtrate and washings are evaporated to dryness, and the residue weighed. As the amount of chloride of sodium and un- decomposed acetate is known, it will thus be ascertained if other substances (albuminoids, $ 223 et seg.) have been dissolved by dilute hydrochlorie acid. Instead of estimating the oxalate as carbonate or oxide, the washed precipitate may be dissolved in dilute sulphurie acid, and the oxalic acid determined by titration with permanganate of potassium. (Cf. $$ 81, 219.) Microscopical Examination.—Oxalate of caleium is always de- posited in plants in the cerystalline condition, and its presence may therefore be confirmed by microscopic examination. "The erystals must be insoluble in water, alcohol, and ether, but soluble in dilute hydrochlorie acid. It should also be ascertained, by means of the microscope, if all the oxalate has been dissolved by the treatment directed in $ 109. If that is not the case, the maceration with dilute acid should be repeated. $ 111. Estimation of Oxalate of Calcium and Pararabin.—I£ the oxalate of calecium is accompanied by pararabin, but not by starch, the maceration is continued for twenty-four hours as before ; but previous to filtering, the whole is rapidly raised to the boiling- point in a flask provided with an upright condenser. A measured quantity of the filtrate (filtered whilst hot) is neutralized with ammonia, and mixed with 2 to 3 volumes of 90 per cent. alcohol. The precipitate, which contains oxalate of calcium and pararabin, is collectted on a tared filter, washed with 60 to 70 per cent. alcohol, dried, and weighed. It is then incinerated, the ash cal- culated to oxalate of calcium, and deducted from the weight of the preeipitate. The remainder is the weight of the pararabin. The filtrate and washings from the precipitate may be evapo- rated to dryness as directed in $ 110, in order to ascertain if other substances have been dissolved. Here, too, albuminous substances may possibly be found, and they may also be present in the preeipitated pararabin. Should that be the case, they may be 8 119—115. CALCIUM, PARARABIN, ETC. 93 estimated by determining the nitrogen in a portion of the preci- pitate. (Of. $ 233.) $ 112. Estimation öf Pararabin alone. —l£ pararabin! alone is present, the estimation may be condueted as described in $ 111, with the exception, of course, that the determination of caleium is unnecessary. After preeipitation with alcohol, pararabin swells in contact with water, but does not dissolve unless an acid be added. It is preeipitated by alkalies, and does not yield arabinose under the influence of dilute sulphuric acid. (Of. $ 245.) $ 113. Estimation of Starch and Oxalate of Caleium.—I£ pararabin is absent, but oxalate of caleium and starch are present together, the material under examination may be boiled (not digested on a water-bath) with 1 per cent. hydrochloric acid for four hours in a flask provided with an upright condenser. The flask is weighed before and after boiling, and any water that may have been lost by evaporation replaced. In one portion of the filtered liquid the oxalate of caleium may be determined as directed in $ 110, and in another the glucose produced from the starch estimated by titration with Fehling’s solution ($ 83). The modification necessary when starch alone is present need® no special description. $ 114. Estimation of Oxalate of Caleium, Starch, and Pararabin.— The following is the method I have adopted when oxalate of caleium, starch, and pararabin are present together. Water is added to the substance under examination in the proportion of 10 cc. for every gram, and the whole brought to the boiling-point. After cooling to 40° or 50°, a centigram or more of good, active diastase is added, and the maceration continued at the same temperature until the starch-paste is completely liquefied. The residue, after filtering and washing, is treated according to $ 111. A measured quantity of the filtrate containing the maltose and dextrin produced from the starch is acidified with hydrochlorie acid and boiled as direeted in $ 113, the glucose being finally estimated with Fehling’s solution and caleulated into starch. S 115. Estimation of Starch alone—If a vegetable substance, especially one rich in mucilage, metarabie acid, pararabin, gluco- sides, etc., is to be examined for starch without previous treat- 1 Compare Reichardt, Ber. d. d. Chem. Ges. viii. 807 (1875) (Journ. Chem. Soc, xxvili. 1179). 94 SUBSTANCES SOLUBLE IN DILUTE ACID. ment with various solvents, a method that I published in 1861! may be adopted by which the substances that accompany the starch are removed. The powdered material is mixed with 30 parts of a 4 per cent. solution of caustic potash in alcohol, and heated to 100° for a day or two in a well-closed flask. After filtering and washing with spirit till free from alkali, the substance on the filter is exhausted with water; and to effect this it is advisable to transfer it to a beaker. The residue insoluble in cold water is boiled with dilute hydrochlorie acid, and treated as directed in$ 113. The caustic potash acts upon the foreign sub- stances which interfere with the direct estimation of the starch, rendering them solyble partly in alcohol, partly in water, whilst the starch itself is not attacked. (See $ 243.) 1 Journ. f. Landwirthsch (May, 1862), and Pharm. Zeitschr. f. Russland, i. 41. For the estimation of starch as glucose after the action of dilute sulphurie acid, see Musculus, Chem. Centralbl., 1860, p. 602 (Am. Journ. Pharm. xxxii. 433) ; and Philipp, Zeitschr. f. anal. Chem. N. F. iii. 400. Sachsse (Zeitschr. f. anal. Chem. xvii.231, 1878; Year-book Pharm. 1878, 97), has shown that the inversion is better effected by hydrochlorice acid—1 per cent. of the weight of the liquid. Both Sachsse and Nägeli found that the analyses of «starch were more accurately expressed by the formula 6C,H,,0; + H,O, than by that usually adopted, viz., C;H},0;. LIGNIN, CELLULOSE, ETC. 95 VL DETERMINATION OF LIGNIN AND ALLIED SUBSTANCES AND OF ÜELLULOSE. $ 116. Lignin, Inerusting and Cuticular Substance. —The residue of the powder insoluble in all the foregoing menstrua, after treatment as directed in $ 109, is washed with water, dried, and weighed. After having been again finely powdered, it is macerated in freshly prepared chlorine-water (in the proportion of about 100 cc. for every gram of substance), until the colour changes to a pale yellow. If 2to 3 days do not suflice, the chlorine- water must be drawn off and replaced by fresh, and this treat- ment repeated if necessary. It is finally collected on a tared filter, and washed first with water, then with very dilute (0°3 per cent.) solution of caustic potash until the washings are colourless, the alkali being ultimately removed by pure water. The loss in weight after drying represents the amount of lignin, the so-called incrusting substances, the majority of the suberin and cuticular sub- stance. (Cf. $ 247.) Bromine-water has been proposed in the place of chlorine-water, but it does not act so energetically. With regard to the microchemical examination, I may observe that lignified tissues absorb fuchsin from its aqueous solution, and retain it so tenaciously that they appear stained deep-red even after maceration in glycerine, which removes all the colouring matter from non-lignified tissue. Russow! recommends the object to be placed on a slide with a drop of dilute aqueous solution of aniline-red. A drop of glycerine is then brought into contact with the edge of the coverslip on the slide, and left for twenty- four hours. Stiles? macerates in a dilute solution of chlorinated lime (1 in 60), then transfers for an hour to a solution of hypo- 1 Sitz-ber. d. Dorpater Naturf. Gesellsch. 1880, p. 419. * Pharm, Journ, and Trans. [3], vi. 741. 96 LIGNIN, CELLULOSE, ETC. sulphite of soda (1 in 32), washes with alcohol, and finally removes to a dilute aleoholie solution of acetate of rosaniline (1 in 960), the excess of which is washed out with spirit. Aniline-blue is said to impart a fine blue or violet colour to the parenchyma of the medullary rays, etc. The solution is made by dissolving 0:0325 gram of aniline-blue in 3°88 gram of water, adding 0:5 gram of strong nitric acid and spirit to 48 grams. After staining red as direeted by Stiles, the section may be immersed for a few minutes in the solution of aniline-blue, washed with spirit and finally treated with cajeput oil or turpentine. Wiesner! has described a qualitative reaction for woody tissue, which consists in moistening the section with a 05 per cent. solution of phlorogluein, and subsequently treating with hydro- chlorie acid. "The lignified tissue assumes areddish or violet colour. $ 117. Estimation of Cellulose —The residue, after treating as directed in $ 116 and weighing, is a mixture of cellulose, inter- cellular substance, remains of the cuticular substance, ete., together with a little ash (and possibly also sand). It may be removed from the filter (which should be reserved), powdered, and introduced into a flask containing 50 to 100 ce. of nitric acid (sp. gr. 1'16 to 1:18) ; 1to 2 grams of chlorate of potash are then added, and the mixture allowed to stand in a cool place with occasional agitation until the insoluble matter appears almost white. If this is not effected in a day or two the mixture may be warmed for one or two hours to about 40° C. (not higher), and again allowed to stand. If this is not successful the strength of the nitric acid may be increased until it reaches a specific gravity not exceeding 1'20. After the action of the acid has been continued long enough, it may be diluted with water and filtered, taking care to pour the supernatant liquid on to the filter, leaving the insoluble matter as long as possible in the flask. After washing free from acid, it is treated with dilute ammonia (1 in 50 of water) as long as that is coloured brownish, and finally with alcohol and, if necessary, with ether. The residue is dried and weighed. The loss in weight usually represents intercellular substance and certain carbohydrates allied to cellulose, but less resistent, (hydrocelluloses), ete. (See 8$ 245, 246.) The residue on the filter consists of cellulose with a little ash (silica, sand, ete.), that may be estimated and deducted. (See also $ 248.) 1 Zeitschr. f. anal. Chem. xvii. 511, 1878 (Journ. Chem. Soc. xxxiv. 612). s 118. CONCLUDING REMARKS. 9 CONCLUDING REMARKS. $118. In compiling the foregoing method of analysis, one object that I had in view was to show how, when working upon a small quantity of material, say 30 to 50 grams, an insight into its composition might be gained, so that at least the presence or absence of the more important constituents of plants might be ascertained. I wished to show further how the constituents actually present might be estimated, even if no more than the above-mentioned quantity was available. I had therefore to devise a combination of qualitative and quantitative analysis, and the fact that a considerable number of the same constituents occur in the majority of plants justified me in making the attempt. Means have also been indicated by which attention would be drawn to the presence of substances that occur only in single plants or in smaller groups of the vegetable kingdom. In this respect the foregoing method is of course but an introduction, the special application and perfection of which for each separate case must be left to the investigator himself. Processes for the quan- titative estimation of certain substances, and especially such as are of considerable practical importance in medicine, agrieulture, etc., have already been recommended, and will be followed by others in the second part of the work. $ 119. It must be admitted that many of the proposed methods of detection and estimation cannot boast of the accuracy attain- able in the analysis of some inorganic substances.. For this reason I advise beginners to refrain from caleulating their analyses, as is frequently done, to the fourth and even fifth place of deci- mals. Such caleulations often mislead readers less acquainted with the subject to attach to the separate determinations an im- portance to which they are not entitled. I consider it ample to carry the caleulations to the second decimal place. To those who ask of what use analyses are, the accuracy of which I have myself this moment questioned, I reply that the object of analyzing a vegetable substance, as for instance ergot, is not so much to ascertain the exact composition of a fungus pro- duced on a certain ear of rye in a certain field, but to obtain information as to the approximate composition of ergot in general, the speeimen under examination being taken as a representative of the drug. Attention must be specially drawn to the fact that 7 98 CONCLUDING REMARKS,. in different years and different localities the proportions in which the constituents of ergot occur present certain variations. If, on the other hand, an approximate analysis is not required, but in its stead a fairly accurate comparison of specimens gathered ‘in different fields, then it must be borne in mind that only certain practically valuable constituents have to be taken into account, for the estimation of which more accurate methods may not unfre- quently be devised. This we are generally able to accomplish, for we are in a position to elaborate the necessary mode of treat- ment, to determine the extent of the errors involved, and the corrections to be made for them, and to make several estimations from the same material from which a mean may be calculated. 8120. FIXED OIL, ETC. 99 IX. SPECIAL METHODS FOR THE ESTIMATION OF GERTAIN ÜONSTI- TUENTS OF PLANTS, SUPPLEMENTARY NOTES TO THE PRE- GEDING EXPERIMENTS. FATS AND THEIR CONSTITUENTIS ; CHOLESTERIN, FILICIN, ETC. 8 120. Estimation of Fixed Oils.—For reasons given in$8,1I recommended the use of benzene some twenty years ago! for extracting fixed oils. Petroleum spirit, which I subsequently introduced for the same purpose, has the advantage over benzene of being more volatile and possessing a lesser solvent power for xesins, ete. (Cf. $ 36.) The use of benzene was afterwards advocated by Hoffmann? also, who gave it the preference over ether and bisulphide of carbon. Other methods for estimating fixed oils have been described by Münch.® Various forms of apparatus that may be used have formed the subjects of commu- nications from Storch,* Wagner, Simon,® Tollens,” Schulze,$ Tschaplowitz,? Medicus,!% Siewert,!! Hirschsohn,!?2 Keyser,1® and others. ui The apparatus represented in Fig. 5 is that last devised by Tollens. It consists of a weighed flask, A, holding about 100 ce., to which is tightly fitted, by means of a perforated cork, a glass tube B; the latter is about 30 mm. in diameter at its upper, and ! Pharm. Zeitschr. f. Russland, i. 44, 1862 ; Anm, Zeitschr. f. anal. Chem. i. 490, ® Zeitschr. f. anal. Chemie, vi. 368, 1867. ® N. Jahrb. f. Pharm. xxv. 8, 1866. @ Zeitschr. £. anal. Chemie, vii. 68, 1868. 5 Tbid. ix. 354, 1870, ° Ibid. xii. 179, 1873 (Journ. Chem. Soc. xxvii. 293). ? Ibid. xiv. 82, 1875, and xvii. 320, 1878. 8 Ibid. xvii. 174, 1878. ® Ibid, xviii. 441, 1879, 10 Tbid. xix. 163, 1880, F Landw. Versuchsst. xxiii. 317, 1879 (Journ. Chem. Soc. xxxvi. 558). 1? Archiv d. Pharm. [3], x. 486, 1877. "3 Farm. Tidskr. 1880, Nos. 9 and 19. 7—2 100 FIXED OIL, ETC. j FR! | m m il rei Sl aa Ess 8122. ELAIDIN, TEST FOR, ETC. 101 5 to 7 at its lower extremity ; the former communicates by means of perforated corks with the condenser D. A glass tube, E, about 20 mm. in diameter, is supported upon a bent glass rod, F, in such a manner that the condensed vapour from C drops directly into it. In this tube, E, the substance to be examined is carefully packed ; a piece of filtering-paper is then tied over the lower end, and a small eireular filter laid upon the surface of the packed substance. During the extraction the heat is so regulated that the material is constantly covered by a layer of ether 1 to 2 cm. thick. $ 121. Resinification.—The rapidity with which an oil resinifies may be ascertained by exposing it to the air in thin layers and noting the daily increase in weight. Parallel experiments should be made with almond and linseed oil under precisely similar con- ditions. The oil used should be quite free from any trace of petroleum spirit. $ 122. Elaidin Test. —This test ($ 12) consists in passing nitrous acid into a few cc. of the oil and observing the length of time that elapses before solidification takes place. Another method is to introduce copper turnings or a little mercury, together with nitrie acid, into a test-tube, and pour a few cc. of the oil upon the mixture. The colour also of the elaidin produced may be characteristic of the oil under examination. Using 5 grams of nitric acid, sp. gr. 1’4, and 1 gram of mercury to 10 grams of oil, Massie! observed the following reactions: On agitating the oil with the nitrie acid alone for two minutes and allowing the liquids to separate, the following colourations were observed : almond, hazelnut, sunflower-seed oil, colourless or slightly greenish ; olive oil, greenish, white or slightly yellowish-green, or distinctly green; ground-nut oil and poppy-seed oil, reddish ; castor and sesame oil, yellowish or yellowish-orange,; oil of white mustard, apricot, walnut, camelina, beech, rape and linseed oil, cherry-red or reddish-orange,; oil of black mustard, cotton and hemp-seed oil, brown or brownish-red. The acid was coloured yellowish by olive oil (occasionally), saffron-yellow by sesame, light brown with cotton, and slightly reddish or greenish by hemp oil. After the addition and solution of the mercury, the mixture is ! Journal de Pharm. et de Chim. [4], xii. 13, 1869, 102 FIXED 0IL, EIC. shaken at intervals and finally set aside. tions were made:: Almond Hazelnut Sunflower-seed Olive Ground-nut Poppy Castor Sesam Apricot White mustard Camelina sativa Walnut Beech Rape Colza Linseed Black mustard Cotton-seed Hemp The following oils solidify : almond in 14 hr., hazelnut in 1 hr., olive oil in 1 hr., ground-nut in 12 hr., sesame in 2} hr., apricot in 12 hr., beech in 6 hr., rape in 3 hr., colza in 34 lır., cotton in 1} hr. ; the remainder do not solidify at all. 8 123. Behaviour to Sulphurie Acid.--Casselman! observed the following rise in temperature when 50 cc. of the oil were mixed After 20 to 30 mins, white or pale-greenish lemon-yellow pale yellowish pale reddish red rose yellowish-orange red yellowish-orange cherry-red orange reddish-yellow pale reddish reddish-brown (effervesces) pale reddish dark orange-red or reddish brown with 10 cc. of cone. sulphuric acid : With the oil from peony-seed Stahre and myself? observed a rise Linseed from 14° to 132° to 134°. Sunflower ,„, 1. OR Poppy „ „ 82. Olive 53 a0 Almond * er 59°, to 68°, whilst almond oil rose to 48°, 8 124. Behaviour to Reagents mentioned in $ 12.—ÜCasselman has made the following observations with the reagents mentioned in 812: 1 Pharm. Zeitschr. f. Russland, 299, 1867 ; Zeitschr. F. anal. Chemie, vi. 479. See also Chateau. 2 Archiv d. Pharm. [3], xiv. 412, 531, 1879 (Journ. Chem. Soc. xxxvi. 1043). The following observa- After 1 hr. white. 2) lemon-yellow. pale yellowish-green. pale reddish. red. yellow. yellowish-orange. rose. reddish-yellow. reddish-orange. reddish-yellow. reddish-orange. orange-yellow. pale yellowish-orange. reddish-brown. reddish-yellow. pale orange-red or red. reddish-brown. 103 8124. BEHAVIOUR TO REAGENTS. 7 arıym "Aoffok Ayysıs "Moe -yYSTU99A13-yYSTu99 a5 NOefg-ystumorg NIeTA-YSTUMOIg “nopaL gystaq| Mofas 4ysrıq "USTLMOIG USTUMOICL 04 Surumg oym uaaıd Yırp ysınopfsf "Molfok umolg ystumorq MoaA Aporeos oyıym KJodawos “opya|Suruumy *uoaıd "Aoffok "sc I un) ’dS JO AIDVY PIULIN Ao0IfoA U991D Rp ON Ya Sr er "'aIoy PIUAHAaTaS ystumoag DUSTHEIPPBA UMOIG-USIPP91|04 Suruany 'oyıyMm umorg Jaup MoffoLk-odurıo| ystumoagq AyYırp uU9915 Jıep UMOLG [UMOIG-USTMOTJOÄ ysıp ystumoag -por oyoyym 04 Surumg -Ys1a07]][9Loya-ystaoppk unorg umolg-ysıppoa|-ysruegad Y18p GL ‘3 (ds “ONH ‘se9-1 | ya vuog rum usru9a1d up “norpek used Yırp gr -umoIg Ayııp Surumg noppk ystumoag Apoaeos “oyıyar u9a1d fyaıp yıup "084-T SNYM uoIs[pnws ayyMm - puowpy umoIg uoIs . pue uooad |-mum oyyMm ‚Zurumg MoJpL-ysımo][9A- - SANO uoIs -nur ofym uooad ywp-ysımo][94- -duoy mIoIS umorg Zur |-nuo oyryMm -umyystmopppi -ysımojfe4- -Addog AN0JO9 OAYA [uorsnwo Sya| Temogung uols u9o1d Ayup)-mwo Mojjak|- Peosur] "Sır-T Be) un) 'dS JO AV PINAHIINS ee re cf Se pm Sa ern a a 104 FIXED OIL, ETC. Stanmic chloride produces the following changes in colour: linseed, dirty yellow, passing to green ; sunflower, white, turning brown ; poppy, greenish ; hemp, yellowish-green ; olive, bright yellow ; almond, scarcely yellowish. On warming with chloride of zinc linseed oil becomes green, and hemp oil assumes a fine green colour, while the remainder undergo no change. Syrupy phosphorie acid forms a sort of emulsion with linseed and poppy oil, but not with the others. Warming with mereuric nitrate colours linseed oil from dark green to brownish-red ; sunflower, bright yellow ; poppy and hemp oil, green, turning brown ; olive, dark yellow, passing to orange red ; almond, deep chrome. Bieber! used nitrie acid of sp. gr. 1'4, and also a cooled mixture of equal parts of conc. sulphuric and fuming nitric acid in the pro- portion of 1 volume of reagent to 5 of oil. Hauchecorne? has published reactions of oils with peroxide of hydrogen, but without specifying the strength of the reagent. He states that on shaking 1 volume of solution of peroxide of hydrogen with 4 of oil, olive assumes an apple-green ; poppy, & flesh colour ; sesame, bright red ; ground-nut, greyish-yellow ; and beech-nut oil, an ochre red. Accordingto Cohng, drying oils may be distinguished from non-drying by their behaviour to peroxide of hydrogen. The former are said to be quickly decomposed with separation of fatty acids, whilst the latter resist ‚such treatment. Basoletto? observed that sesam& oil, when shaken with an equal volume of hydrochloric acid (23 to 24 per cent) containing 2 per cent. of cane-sugar, assumed a reddish tinge, passing to cherry-red, whilst olive oil was not coloured. On agitating with nitrie acid containing sugar, sesam& oil was coloured cinnamon, whilst the acid became yellowish-green. Cotton-seed oil turns yellow with the same reagent (the acid becoming pale rose coloured), but 1 Apotheker Zeitung, xii. 161, 1877 (Journ. Chem. Soc. xxxiv. 343). For the action of nitric acid on fatty oils, see also Hauchecorne, Zeitschr. f. anal. Chemie, iii. 512, 1864, where, however, the strength of the acids employed is not mentioned. Langlies (ibid. ix. 534, 1870) recommends mixing nitrie acid specific gravity 1'4 with # of its volume of water, and warming 1 part of this reagent with 3 of oil in the water-bath. Sesame oil is said to yield a red mass by this treatment. 2 Zeitschr. f. anal. Chemie, ii. 442, 1863. 3 Bulletin della Soc. Adriatie, i. 178, 1875. 8124. BEHAVIOUR TO REAGENTS. 105 almond and castor oil produce no alteration. According to Vidan! hydrochlorie acid containing sugar changes the colour of castor oil to orange-yellow, poppy oil yellowish-brown, ground- nut oil intense yellow, olive oil yellowish-orange, rape oil dark brown, and almond oil yellowish-orange. For the use of chloride of antimony as a reagent see Zablu- dowski? and Walz? The latter found that on adding a few drops of the reagent, which should be of a syrupy consistence, to %or 3 ce. of the oilto be examined, olive oil formed a whitish emulsion, gradually turning dark, without any rise in tempera- ture, whilst with cotton-seed oil a considerable amount of heat was evolved, the mixture becoming solid and of a chocolate-brown colour. Concentrated solution of chlorinated lime is said to form an emulsion with 8 times its volume of poppy oil, but not with almond oil. Caustic soda of specific gravity 1'33, heated to boiling with 4 or 5 times its volume of oil, yields a white liquid mixture with castor oil, yellowish-white with sesame, colza, poppy, and walnut, and yellow with linseed, whilst olive oil and hemp yield respectively brownish and brownish-yellow solid masses.* Some oils, such as rape and colza, may be contaminated with sulphur compounds, which may be detected by nitro-prusside of sodium after treatment with caustic soda. For the use of the spectroscope in identifying fixed oils see Gilmour,? of the polariscope see Buignet,® of cohesion figures see 'Tomlinson,? Kate Crane,$® and Moffat.? $S 125. Free Fat-acid.—The presence of free fat-acid may be ! Journ. de Pharm. et de Chim. xxii. :30, 1875 (Journ. Chem. Soc. xxix. 111). Compare also Jahresb,. f. Pharm. 288, 1875. The hydrochloric acid and sugar reaction was recommended by Camoin as early as 1860. Compare Choulette, ‘Observations prat. de Chim. et de Pharm.’ Fasc. i. 130. ® Pharm. Zeitschr. f. Russland, ii. 233, 1863. ? Amer. Journ. Pharm, xlvi. 25, 1874. - * Compare Hager, “ Untersuchungen ’ (Günther Leipsic, 1874), vol. ii. 510. 0 Journ. and Trans. [3], vi. 981, and Jahresb. f. Pharm, 362, 16. ER ’ ourn, de Pharm. et de Chim. xl. 252, 1862 (Amer. Journ. Pharm, xxxiv. 7 Pharm. Journ. and Trans. [2], v. 387, 495. 8 Ibid. [3], v. 243, and Jahresb. f. Pharm. 289, 1874. ® Chem, News, xviüi. 473. x‘ 106 FIXED OIL, ETC. detected, according to Jacobson,! by shaking with powdered rosaniline Oil containing free fat-acid is coloured red. Rumpler? employs carbonate of soda, which does not emulsify oils containing no free fat-acid. Geissler? estimates the free fat-acid by diluting with 2 or 3 volumes of’ ether and titrating with alcoholie potash, using an alcoholice solution of rosolic acid or phenol-phthalein as an indi- cator: $ 126. Cholesterin. Detection and Estimation.—Hoppe-Seyler ® detects and estimates cholesterin in vegetable substances by ex- tracting with ether, distilling, boiling the residue for a few hours with alcoholie potash, evaporating, redissolving in water, and shaking with ether. If the cholesterin obtained by evaporating the ethereal solution is not pure, the treatment with alcoholic potash is repeated. If sufficient alkalı is present neither fat nor soap will be taken up by the ether. Schulze? directs attention to the fact that the estimation is inaccurate if the material contains vegelable waxw yielding an alcohol ($ 14) on decomposition with an alkali, on account of the influence the latter exereises on the solubility of cholesterin in spirit. Schulze recommends the conversion of the impure cho- lesterin into benzoate of cholesteryl by heating with benzoie acid in sealed tubes. This compound may be freed from many foreign substances by boiling with absolute alcohol, in which it is almost insoluble. After reerystallization from ether the cholesterin may be liberated by heating with alcoholie potash. Cholesterin is soluble in petroleum spirit as well as in ether, and. is therefore extracted by the former, together with the fixed oil. If an accurate estimation is required, large quantities of material must be worked upon, as cholesterin occurs in only small pro- portions in vegetable substances. (Beneke obtained 1:5 gram from 2,500 grams of grey peas.) It is insoluble in water, erystal- - lizes from alcohol in silky needles and plates (belonging to the rhombie system), melts at 137°, and is, in alcoholie solution, laevo-rotatory («an =36'61°). Warmed with a mixture of 1 vol. 1 Chem.- tech. Repert. i. 84 ; Zeitschr. f. anal. Chemie, xvü. 387, 1878. 2 Zeitschr. f. anal. Chemie, ix. 417, 1870. 3 Ihid. xvii. 387, 1878 (Journ. Chem. Soc. xxxiv. 334). 4 Ned.-chem. Unters. Heft i. 143. Zeitschr. f. anal. Chemie, v. 422, 1866. 5 Zeitschr. f. anal. Chemie, xvii. 173,1878. (Journ. Chem, Soc. xxxiv. 612.) s 126. PHYTOSTERIN, ETC. 107 conc. sulphurie acid with 1 of water, a red colouration is Pro- duced, whilst 4 of acid with 1 of water develops a blue, and 3 with 1 a violet tinge. If a mixture of concentrated hydro- chlorie acid and solution of ferric chloride (3 in 1) is eva- porated with a little cholesterin, a reddish-violet or bluish-violet colour makes its appearance. Similar treatment with sulphuric acid and ferric chloride leaves a carmine residue, which gradually passes to violet and becomes scarlet on treating with ammonia.' After trituration with sulphurie acid cholesterin is coloured red by the addition of chloroform. Phytosterin, a substance allied to and probably homologous with cholesterin, was discovered by Hesse? in the Calabar bean. Its solubility is, on the whole, similar to that of cholesterin, with which it has occasionally been confounded. It meltsat 133°, and is somewhat less powerfully leevo-rotatory (@) = 34'2°). Filiein is another substance soluble in petroleum spirit; it is extracted, therefore, together with the fixed oil, and is partially deposited in erystals on evaporating such a solution ; an appre- ciable quantity, however, remains dissolved in the fixed oil. Experiraents made at my instance by Kruse,? with the object of devising a quantitative separation of filiein from fixed oil, were unsuccessful ; all the liquids employed (acetone, acetic ether, ether, heavy petroleum oils, bisulphide of carbon, ete.) dissolved both substances. Attempts to separate the fixed oil from the filiein by dissolving in a hot aqueous solution of carbonate of soda and fractionally precipitating with hydrochloric acid, as well as the same treatment of an alkaline alcoholic solution, were attended with negative results. The kosin® contained in cousso is soluble in petroleum spirit, especially when warm. It is more easily soluble in ether, benzene, or bisulphide of carbon, somewhat sparingly in alcohol and glacial acetic acid. Ferrie chloride colours the aleoholie solution red, and ! Zeitschr. f. anal. Chemie, xvii. 173, 1878, and Ritthausen, ‘Eiweiss- körper,’ 98. ® Annal. d. Chem. und Pharm. excii. 175, 1878 (Journ. Chem. Soc. xxxiv. 850). For paracholesterin, see ibid. cevii. 229, 1881. Hesse, ibid. cexi. 283 5 Schulze and Barbieri, Ber. d. d. Chem. Ges. xv, 953, 1882. ® Archiv d. Pharm. [3], ix. 24, 1876 (Journ. Chem. Soc. xxxi. 336). See also Luck, Annal. d. Chem. und Pharm. liv. 191, 1851, and Grabowski, Chem. Centralbl. 409, 1867. * Flückiger and Buri, Archiv d. Pharm. [3], v. 193, 1874 (Pharm. Journ. and Trans. [3], v. 562). 108 FIXED OIL, ETC. an alkaline aqueous solution also gradually assumes a red tinge. It is decomposed by fusion with potash, yielding, amongst other substances, butyrie acid (the same is the case with filiein). Euphorbon! is likewise soluble in petroleum spirit, and freely so in ether, benzene, chloroform, acetone, and glacial acetic acid, but not in aqueous alkalies. It dissolves in concentrated sulphurie acid, with the production of a brownish tinge, which is changed to violet by nitre or nitric acid. It melts at 113° to 114°, and resembles, in many of its properties, lactucon or lactucerin (various species of Lactuca), echicerin (dita bark), and perhaps also cynan- chocerin (Cynanchum vincetoxicum and acutum). Helenin is easily soluble in petroleum spirit, alcohol, and ether, but insoluble in water, even in the presence of a little alkali ; it is dissolved, however, by hot concentrated solution of potash. Helenin melts at 110°, crystallizes in colourless needles, and dis- solves in conc. sulphuric acid, with production of ared colouration. Hydrochlorie acid-gas is also said to colour helenin red.” Coumarin may be recognised by its odour and by its colourless rhombie erystals. It is sparingly soluble in cold, more easily in hot water, and is also dissolved by ether and by alcohol. Amongst the substances it yields when fused with potash is salieylic acid ($ 26). For the allied melilotie acid compare Zwenger.? Styrol also is characterized by its aromatie odour. It is a colour- less liquid convertible by long heating in sealed tubes into solid metastyrol. It is almost insoluble in water, but easily soluble in alcohol, ether, and bisulphide of carbon. Heated with chromie acid it yields benzoic acid and other products of decomposition ($ 26). For myroxocarpin, see Stenhouse and Scharling ;* for diosmin, Landerer® and Fluckiger ;° for kämpferid, Brandes and Jahns ;7 for asaron (which is soluble at least in warm petroleum spirit), 1 Hesse, Annal. d. Chem. und Pharm. clxxx. 352; clxxxii. 163, 1876; excii, 193, 1878 (Amer. Journ. Pharm. 1. 552). See also Alberti and Dragen- dorff, Pharm. Zeitschr. f. Russland, ii. 215, 1863; and Flückiger, N. Jahrb. f. Pharm. xxix. 135, 1868. 2 See Kallen, Ber. d. d. chem. Ges. vi. 1506, 1873 (Pharm. Journ. and Trans. [3], vii. 156). 3 Annal. d. Chem. und Pharm. Suppl. v. 100, 1867. 4 Ibid, Ixxvii. 306, 1851, and xevii. 69, 1856 (Amer. Journ. Pharm. xxiii. 144). 5 Repert. f. Pharm. Ixxxiv. 62. 6 Ibid. xxiii. (New Series), 102, 1874 (Amer. Journ. Pharm. xlvi. 235). 7 Archiv d. Pharm. lviii. 52; Ber. d. d. chem. Ges. xiv. 2385. gs 197, 128. CAOUTCHOUC, ETC. 109 C. Schmidt ;! for angeliein, which has been proved to be identical with hydrocarotin, see Brimmer ;? for carotin, see Husemann.® The last-named substance forms red erystals, soluble in benzene and bisulphide of carbon. It dissolves in cone. sulphurie acid, with a purplish-blue colour, and is also coloured blue by sulphurous-acid- gas. Anemonol, which occurs in many Ranunculacex, may also be mentioned here. Itisan oily acrid liquid, volatile with the vapour of water, and gradually changing in aqueous solution to erystalline anemonin. The latter can be isolated by shaking the aqueous solution with ether or chloroform, and like anemonol, acts as an irritant when applied to the skin.® For capsiein and capsaicim see Thresh ; for amyrin and bryoidin see Buri.® $ 127. Caoutchouc.—Petroleum spirit extracts only a trace of caoutchouc, which remains undissolved on treating the residue after evaporation with warm absolute alcohol. If a considerable quantity of caoutchouc is present the majority is left in the sub- stance after exhaustion with petroleum-spirit, and may be extracted by bisulphide of carbon containing 6 to 8 per cent. of alcohol, or by chloroform. From these solutions it may be precipitated by the addition of more alcohol, whilst resinous substances and the like generally remain dissolved. (See also $ 46.) $ 128. Estimation of Glycerin ($ 13).—For details of the deter- mination of this substance see Reichardt,” and Neubauer and Borgmann.® The latter authors point out the fact that ether- alcohol removes other substances besides glycerin from wine, etc., and that the estimation may accordingly be too high. They therefore recommend dissolving the glycerin residue in alcohol, adding 3 volumes of ether, filtering and evaporating. Pasteur advises the evaporation of the solution to be conducted as quickly 1 Annal. d. Chem. und Pharm. liii. 156, 1845, ? N. Repert. f. Pharm. xxiv. 665, 1874 (Pharm. Journ. and Trans. [3], vü. 91). ® Annal. d. Chem. und Pharm. exvii. 200, 1861, 4 Compare Fehling, Annal. d. Chem. und Pharm. xxxviü. 278,1841 ; Müller, Chem. Centrlb. 618, 1850 ; Erdmann, Journ. f. prakt. Chem. Ixxv. 209. See Amer. Journ. Pharm. xxxiv. 300 ; xxxi. 440, ° Pharm. Journ. and Trans. [3], vi. 941, vii. 473, 6 N. Repert. f. Pharm. 220, 1875 (Pharm. Journ. and Trans. [3], vü. 157). 7 Archiv d. Pharm. [3], x. 408 ; 131, 31.142221877. ® Zeitschr. f. anal. Chemie, xviii. 442, 1878, See also Pasteur, Annal. d. Chem. und Pharm. lviii. 330, 1864. 110 FIXED OIL, ETC. r as possible, as glycerin loses weight even in a vacuum. Compare also Griessmeier and Clausnitzer.! $ 129. Wax. —Cetyl alcohol ($ 14) melts at 48° to 49°, and at 54° is miscible with spirit of specific gravity 0'812 in all proportions. Cerotyl alcohol melts between 79° and 81°, melissyl alcohol at 85°. The latter is scarcely soluble in cold alcohol, benzene, petroleum spirit, or chloroform, but dissolves on boiling. König and Kiesow found a substance in meadow-hay which they considered to be cerotene, or a ‘paraffin’ of the composition C,,H,..? Hirschsohn has endeavoured to find distincetive characteristics for certain vegetable waxes that find application in the arts,? with the following results : Wax from Myrica quercifolia—Soluble in 10 parts of boiling chloroform ; the solution remained clear on cooling. Completely ' soluble in ether. 95 per cent. spirit dissolved 16°16 per cent. at the ordinary temperature ; petroleum spirit 53 to 62 per cent. The alcoholie solution gave a precipitate with alcoholie- ferric chloride (1 in 10), which did not dissolve on warming. Wax from another sp. of Myrica yielded 19-88 per cent. to alcohol, 6870 per cent. to petroleum-spirit. Ferric chloride coloured the alcoholic solution black. Wax from Myrica cerifera yielded 716 per cent. to alcohol and 41'62 per cent. to petroleum spirit. Ferric chloride coloured the alcoholie solution brownish. Wax from Rhus succedanea (Japan wax) resembled the three foregoing waxes in being completely soluble in chloroform, but was only partially soluble in ether. Alcohol dissolved 14 per cent., petroleum spirit 69'8 per cent. Boiling with 10 parts of 10 per cent. alcoholic potash saponified it ; the soap was completely soluble in 100 parts of water, whilst that from beeswax was only partially dissolved. Wax from Aleurites laccifera—Ihe solution in chloroform became turbid on cooling ; the addition of an alcoholie solution of acetate of lead to a similar solution of the wax caused a cloudiness on standing. Boiling alcohol left a pulverulent substance un- dissolved. 1 Ber. d. d. chem. Ges. xi. 292, 1878 (Journ. Chem. Soc. xxxiv. 449), and Zeitschr. f. anal. Chemie, xx. 58, 1881 (Journ. Chem. Soc. xl. 470). 2 Ber. d. d. chem. Ges. vi. 500, 1574. For vegetable wax see also Ludwig, Archiv Pharm. [3], i. 193. 3 Pharm. Journ, and Trans. [3], x. 749. 88 129, 130. WAX, ETC. 111 Carnauba wax behaved similarly to chloroform and alcohol, but acetate of lead caused no eloudiness. It was partially soluble in ether ; the ethereal solution became turbid on the addition of alcohol. Cold alcohol dissolved 325 per cent., Dotzolgue: -spirit 5.04 per cent. Bahia wax resembled carnauba wax in most of its properties, but the addition of alcohol did not render the ethereal solution turbid. Cold aleohol dissolved 9:7 per cent., petroleum spirit 3:32 per cent. For cerosin from the sugar-cane see Avequin,! Dumas,? and Lewy.°® Wax may be recognised mier ochemicallı 'y as a solid exudation on the surface of the cells, insoluble in water and partially or wholly soluble in ether. (See also $$ 14, 15, 145.) ‘8 130. Oleic and Linoleic Acids. —Oudemans? has adopted the following method for the estimation of oleie acid. The soap obtained by saponifying about 10 grams of the fat with potash is decomposed with sulphurie acid; the fat-acids are washed with _ water, mixed with excess of carbonate of soda and dried. The dry mass is exhausted with boiling. alcohol, filtering whilst hot ; to the aleoholie solution a little water and an excess of acetate di lead is added. The lead preeipitate is collected and dried ; and from a weighed portion the oleate of lead is extracted by boiling with ether. The oleie acid may be caleulated from the weight of the residue obtained by evaporating the ethereal solution. Linoleic acid has not yet been isolated in a state of purity, as the free acid when exposed to the air oxidizes even more rapidly than the corresponding glyceryl compound. Mulder estimated it approximately by separating it, together with oleic, palmitie and myristic acid, from the soap, dissolving the mixed fat-acids in alcohol, carefully evaporating, allowing the palmitic and myristic acids to erystallize out, and finally converting into the lead salts. Extraction with ether then removes oleate and linoleate of lead. By repeated evaporation in contact with air and re-solution in ether, the linoleate of lead gradually becomes insoluble, whilst oleate of lead does not change.’ 1 Annales de Chimie et de Physique, Ixxv. 218. ® Ibid. 238; Annal. d. Chem. und Pharm. xxxvii. 170, 1841. 3 Tbid. (New Series), xiii. 451. 4 Journ. f. prakt. Chem. xcix. 407, 1877. 5 Compare Zeitschr. f. Chem. ii. 452, 1866 (Amer. Journ. Pharm. xl. 249) ; Schüler, Jahresb. f. Pharın. 155, 1857. ” 112 FIXED OIL, ETC. Of lauric acid, Oudemans observes that it is easily volatile with the vapour of water, which is not the case with myristic and oleie acid ($ 15). (Myristic and other fat-acids may however be distilled in vacuo.) Oleic and stearic acids may be separated, according to David,! by precipitation from alcoholie solution with glacial acetic acid (1 volume to 3 of 95 per ar RR! Oleic acid is not thrown out even by the addition of 22 cc. of a mixture of equal volumes of glacial acetic acid and water to 3 cc. of alcoholie solution. Under these eircumstances stearic acid would be completely separated. (See $$ 16, 131.) $ 131. The separation of resins from fat-acids in soap-analysis has formed the subject of communications from Jean,? Barfoed® and Gladding.* The following partieulars are taken from Barfoed : a. Stearic and palmitic acids are soluble in hot 70 per cent. spirit, but separate out on standing twenty-four hours in a cool place, Coniferous resin (abietic acid) dissolves in 10 parts of cold spirit of the same strength, but is precipitated on adding water containing hydrochloric acid. b. I£ a mixture of the same fat-acids with resin is boiled with 7 volumes of 30 per cent. spirit, to which 1 volume of an aqueous solution of carbonate of soda (1 to 3) has been added, both resin and fat-acid dissolve On cooling, the soap produced from the fat-acids separates out, whilst the resinate of soda remains in solution. The fat-acids may be obtained from the precipitate by filtering off, washing with alcoholie carbonate of soda solution and decomposing with hydrochlorie acid, whilst the filtrate yields the resin on treatment with an acid and shaking with ether. c. On adding a solution of 1 part of chloride of caleium in 15 of 80 per cent. spirit to a hot solution in spirit of the same strength, and cooling, the caleium salts of both fat-acids separate out, whilst that of the resin acid remains in solution. d. If stearic and palmitie acid and resin are dissolved in oa the solution evaporated to dryness, powdered and extracted with a 1 Zeitschr. f. anal. Chem. xviii. 622, 1879 (Journ, Chem. Soc. xxxiv. 1011). 2 Polyt. Journ. cevii. 1873 (Journ. ©hem. Soc. xxvi. 195). 3 Zeitschr. f. anal. Chem. xiv. 20, 1875 (Journ. Chem. Soc. xxix. 771). Compare also Gottlieb, Poliz. chem. Skizzen, Leipzig, 1853 ; and Sutherland, Chem. News, 1866, 185. 4 Chem. News, xlv. 159, 1882. CHLOROPHYLL. 113 inixture of 1 volume of 98 per cent. spirit to 5 of ether, the resin compound alone passes into solution. Gladding’s method depends upon the insolubility of the silver salts of fat acids in ether, in which resinate of silver dissolves both easily and abundantly. For working details of the process reference must be made to the original paper. If oleic acid is present, the separation by a and b will be inac- curate, as the resin will be contaminated with oleic acid. "These methods might, however, be employed to separate oleie Irom stearic and palmitie acid in absence of resin. If only a small quantity of oleie acid is present, the resin may be estimated by e. On decomposing the lime salt with an acid, a little oleie acid may be precipitated with the resin, but the former remains sus- pended in the liquid, whilst the latter agglutinates into lumps. After separating the resin, the oleic acid may be removed by shaking the liquid with ether. The estimation of resin in the presence of oleic acid is, however, best accomplished by d. The mixture must be well dried and the ether-alcohol made from anhydrous spirit and ether ; 1 part by weight of oleate of soda dissolves in 935, 1 of resinate of soda in 7'9 parts of ether-alcohol. CHLOROPHYLL AND ALLIED SUBSTANCES. $ 132. Chlorophyll. —Notwithstanding that the chemical nature of chlorophyli is still involved in considerable obscurity, I treated it in $ 20 as a homogeneous body, and at the same time pointed out that the chlorophyllI-granules observable under the microscope contain solid albuminous substances, starch, ete., in addition to chlorophyll. It has been satisfactorily proved by Fremy! and others that chlorophyll may be separated by treatment with hydrochloric acid and ether or benzene into two colouring matters, one of which, cyanophyll or phyllocyanin, is blue and soluble in ether and ! Comptes Rendus, 1. 405, 1860, Ixi. 188, 1865; Journ. f. prakt. Chem. Ixxxvii. 319, 1862. See also Kromayer und Ludwig, Archiv d. Pharm. clvi. 164, 1861; Ad, Archiv d. Pharm. cexcii. 163, 1870 ; Kraus, ‘Zur Kenntniss des Chlorophyllifarbstoffes,” Stuttgart, 1872; Wiesner, Chem. Centralblatt, 353, 1874; Filhol, Comptes Rendus, Ixi. 371, Ixxix. 612, 1874; Hartsen, Annal. der Phys. cxlvi. 158, 1874; ‘Neue chemische Untersuchungen,’ Forstemann, 1875 ; Archiv d. Pharm. [3], vii. 136, 1875. 8 G 114 CHLOROPHYLL. benzene, the other, xanthophyll or phylloxanthin, yellow and insoluble. These two substances exist, according to Fremy, side by side in chlorophyll. In this opinion, however, he is opposed by Prings- heim and others,! who assert that they are only products of its decomposition. Sorby, again, does not consider the existence of a chlorophyl], a phyllocyanin, or phylloxanthin of definite chemical composition to be probable, but rather antieipates in them repre- sentatives of whole series of such compounds. Which of these opinions may be correct it is impossible at the present time to decide. Whether the green colouring matters isolated by Filhol, Sachsse,? and others, and said to differ spectroscopieally from ordinary chlorophyll, are of artificial origin, or whether they can be produced by the plant itself ; what relation probably exists between chlorophyll, ‘ purified chlorophyll,’ or chlorophyllan and cyanophyll ; between xanthophyll, Hartsen’s erystalline -chryso- phyll and Pringsheim’s hypochlorin, are questions involved in still greater obseurity. I restriet myself, therefore, here, to stating that “chlorophyll’” can be extracted from vegetable substances by boiling alcohol after exhaustion with water ; a little, however, is retained by the residue insoluble in alcohol, as benzene still extracts a green colouring matter possessing all the characters of chlorophyll. ® 1 Chem. Centralblatt, 299, 316, 331, 1880. 2 ITbid. 121, 1878. 3 That the chlorophyli exists in different states of combination is rendered pro- bable by the fact that if vegetable substances are exhausted with petroleum spirit, benzene, ether, etc., in succession, each of these solvents removes chloro- phyll, so that when petroleum spirit fails to dissolve more of it, appreciable quantities can still be extracted with benzene. This combination might be con- ceived to be simply mechanical, the protoplasm acting in a similar manner to hydrate of aluminium which, as is well-known, has the power of mechanically retaining chlorophyll. But the question may also be raised whether chlorophyll, which, in the opinion of many authors, possesses the characters of a weak acid, does not exist in plants in combination with different bases, and whether soluble (basic) alkali-compounds, such as those artificially produced by Fremy, do not oceur ready-formed in some plants. Every one that has been frequently engaged in plant-analyses must have observed that well-filtered aqueous extracts of leaves, ete., when acidified and shaken with benzene or ether, yield to those solvents substances which on evaporation assume a green tinge and possess all the characteristic properties of chlorophyll. 'The assumption of the presence in the aqueous extract of a colourless chromogene converted during the successive operations into chlorophyll would, it is true, be possible, but I cannot as yet regard the first view as untenable. The whole subject, indeed, appears to me deserving of further investigation. -8 134. ERYTHROPHYLL, OHLOROPHYLLAN, ETC. 115 After acidulating the alcoholic extract with hydrochlorie acid and diluting with a little water, the chlorophyll may be removed by shaking with benzene, xanthophyll remaining in the alcoholie liquid. Under these circumstances, however, the chlorophyll is unfortunately always accompanied by fatty matter, etc. $ 133. Estimation of Chlorophyll.—Should it appear desirable to isolate the chlorophyll for the purpose of weighing (cf. $ 37), advantage might possibly be taken of an observation made by Sachsse,! viz., that a benzene solution of chlorophyll, on standing for a few days over metallic sodium, deposits a green mass capable of being filtered off from the golden-yellow solution. With the exception of its containing sodium, it agrees with chlorophyll in most of its more important characters, although, of course, it no longer represents that substance in an unaltered state. It dissolves in water, but is completely precipitated by sulphate of copper. The copper compound thus formed may, however, be contaminated with carbonate. From it the colouring matter may be isolated by suspending in alcohol, passing a current of sulphuretted hydrogen through the mixture, and evaporating the aleoholie filtrate. The residue may be weighed. S 134. Erythrophyll, Chlorophyllan, ete.—By first freeing grass from wax by treatment with ether, and then exhausting with aleohol, Hoppe-Seyler? succeeded in isolating from. unaltered _ ehlorophyll a greenish-white colouring matter, sparingly soluble in alcohol, erystallizing in four-sided plates, and appearing red by transmitted light. This substance seems to be identical with Bougarel’s? erythrophyll. Hoppe-Seyler also separated a second substance, which was more easily soluble in hot aleohol, erystallized in needles, and appeared dark green by reflected, but brown by transmitted, light. This body, which he terms chlorophyllan, agrees with the so-called chlorophyll in most of its properties, especially the spectrum, in which, however, the bands in the yellow and green are somewhat deeper than they are in the ordinary chlorophyll-speetrum (SS 148 and 20). Hoppe-Seyler thinks it possible to make approximate estimations of chlorophyll by titration with spectroscopic end-reaction.* Gautier has also ! Chem. Centralblatt, 121, 1878 ; 741, 1880. ? Ber. d. d. chem. Ges. xii. 1555, 1879 ; xiii. 1244, 1880 (Journ. Chem. Soc. xxxviii. 53, 894), 3 Bulletin de la Soc. Chim. xxvii, 442, 1879 (Journ. Chem. Soc. xxxi. 790). 4 For the chlorophyll contained in certain Floride, see Pringsheim, loc. eit, 8» ’ 116 CHLOROPHYLL. isolated from the leaves of dieotyledonous plants a crystalline chlorophyll,! which ‘Hoppe-Seyler suspects to be a mixture of erythrophyll, chlorophyllan and wax. Gautier’s analyses agree tolerably well with those of Hoppe-Seyler’s chlorophyllan. S 135. Xanthophyli (phylloxanthin), the yellow colouring matter to which the autumnal tint of many leaves is ascribed, appears to be insoluble in water, sparingly soluble in cold ether, petroleum spirit, or benzene. Alcohol dissolves it more readily, and it is soluble also in ether-alcohol. It may be obtained as a yellow granular deposit contaminated with fatty matter by evaporat- ing an alcoholic extract (Berzelius). Dilute acid and dilute potash and ammonia are said to dissolve it but sparingly ; the latter may, therefore, be employed to effect a partial separation from fat, ete. Sulphurie and hydrochlorie acids colour it only faintly blue. If the alcoholic extract has been shaken with benzene, as directed in $ 132, the residue obtained on evaporating - the benzene solution may be purified by suitable treatment with the foregoing liquids, especially petroleum spirit.? Hartsen thinks that his chrysophyll is possibly identical with phylloxanthin. Hrypochlorin.—Pringsheim® states that hypochlorin separates from the chlorophyll granules in the form of yellow drops, which gradually become crystalline. It is insoluble in water, dilute acids and solutions of salts, but is easily dissolved by ether, benzene, bisulphide of carbon and ethereal oils. Im concentrated and dilute alcohol it is at one time easily, at another difficultly, soluble. Possibly it is volatile with the vapour of water. It would be premature, on the basis of the facts that have as yet been established, to assert the identity of hypochlorin with xanthophyll ; the latter is certainly not identical with etiolin, the yellow colouring matter of etiolated plants, which in aleoholie solution assumes a green tinge, and, after the lapse of some un is coloured blue by hydrochlorie acid. for the colouring matter of certain Alg&, see Sachsse, ‘Chem. und Phys. d. Farbstoffe, Kohlehydrate und Proteinsubstanzen,’ Leipzig, 1877. 1 Bulletin de la Soc. Chim. xxviii. 147, 1879 (Journ. Chem. Soc. xxxviii. 266). 2 For the relation that xanthophyll (etiolin) bears to chlorophyll, see Wiesner, Annal. d. Phys. und Chem. cliii. 622, 1874, and Chem. Centralblatt, 353, 1874; also “Die Enstehung d. Chlorophyll’s in der Pflanze,’ Wien, Hölder, 1874. 3 C'hem. Centralblatt, 9, 27, 299, 316, 331, 1880. Compare also Jahresb. f. Wissensch. Bot. 1874. See Quarterly Journ, Mic. Soc. 1881. 8 136. ETHEREAL O0ILS. 117 ‚Anthoxanthin, the yellow colouring matter in the petals of many flowers, also differs from xanthophyll. . It occurs in two varieties, one of which (anthochlor, xanthein) is soluble in water, whilst the other (xanthin, lutein) is dissolved only by ether and alcohol. The latter turns green and blue on the addition of hydrochlorie acid. ETHEREAL OILS, VOLATILE ACIDS, ETC. $ 136. Estimation.— The following estimations are taken from Össe, and given here in illustration of the method recommended in $ 22: I. 0'277 gram of oil of turpentine was diluted with petroleum spirit to 10 cc. ; 1 cc. of the solution was evaporated as described in $ 22. The weight of the residue was 0'046 gram, which, after exposure to the air for 1 minute, decreased to 0026 gram (differ- ence, 0:02) ; after a second minute’s exposure, 0:0205 gram (dif- ference, 0°0055) ; after a third, 0'017 gram (difference, 0'0035) ; after a fourth, 00135 (difference, 0:0035). "The weight of the turpentine taken is caleulated from the third weishing, 00205 gram, to which is added 2 x 0:0035 gram, making a total of 0'0275 gram from 1 ce., or 0'275 gram from 10 cc., instead of 0277 gram. Asecond estimation gave 0'267 gram ; mean 0'271 gram. II. 0:1268 gram of oil of lemon was diluted to 5 ce. with petro- leum spirit, and 1 cc. taken for evaporation. lst weighing = 0'0505 nd , = 0:0250 dit. = 0:0255, SA ,., 00185 „ = 0.0066: th „= 00165 „ = 000%. ERHI OO , -=000 To the third weighing, 0'0185 gram, there is to ber added 2x 0:002 gram, giving a.total of 0'0225 gram from 1 ce., or 0.1125 gram from 5 ce., instead of 01268 gram. A repetition of the estimation gave 0'1275 gram ; mean 01200 gram instead of 01268 gram. Ill. 0166 gram of oil of cinnamon diluted to 10 60 5. Lice, taken for evaporation. lst weighing = 0'0317 nd , = 00171 di. = 0:0146, Id 5, =00168 „ = 0:0008. th „= 0'0160- ,„ = 0°0008. Sth „ = 00157 „ = 0:0008. The third weighing, 00163, represents the quantity of oil present, since no correction has to be made, as the co-eflicient of 118 ETHEREAL 0ILS. evaporation is less than 0'001. 10 ce. would, therefore, contain 0'163 gram instead of 0'166 gram. s 137. Estimation with Bisulphide of Carbon.— Instead of petro- leum spirit, Osse also tried bisulphide of carbon, as recommended by Hager ! for the quantitative estimation of camphor, as well as mixtures of both liquids, without attaining better results. He has therefore decided in favour of petroleum spirit alone, which, however, should not contain any oils boiling at a temperature higher than 40° C., In analyzing vegetable substances such a petroleum spirit is preferable to mixtures of the same with bisulphide of carbon, as it has a lesser solvent power for resins, ete. Ethereal oils may be extracted from their aqueous solutions by petroleum spirit,? and may therefore be estimated in the aqueous portion of the distillate ($ 24) by shaking with that solvent and evaporating & measured quantity of the solution after separation from the aqueous liquid. I havealso employed this method for estimating the essential oil in the oflicial aromatie waters. $ 138. Influence of Fixed Oil.—Osse also made experiments with the view of ascertaining whether the presence of fixed oil could affect the determination of ethereal oil, either by itself increasing in weight during the exposure to the air or by preventing the eva- poration of the ethereal oil at 110°C. He found that a pretty close approximation to the truth might generally be arrived at by deducting 0°09 to 0'1 per cent. from the weight of the fat after heating to 110°. No appreciable error would be caused by the oxidation of the fixed oil during the evaporation of the petroleum spirit, as the presence of the latter, even in small quantities, pre- vents or delays such change. 0'875 gram olive oil was mixed with 0'051 gram oil of turpen- tine and heated for an hour to 110° C. The weight of the residue was 0'875 gram, which did not alter if the heating were continued two hours longer. 1'4265 gram olive oil and 0°0575 gram oil of einnamen weighed after 1 hour at 110° . ’ . 1'436 gram. 2 ji . „1485 „ Bey, er ; IB815 ! Pharm, Centralblatt, xiii. 449. 2 Dragendorff, paper read at a meeting of the German ‘ Apothekerverein’ in Cologne, 1873 ; ‘ Ermittelung der Gifte,’ 2nd ed., 46, 1876, $ 139. SEPARATION OF VOLATILE ACID 38 I obtained similar results in experiments with cacao butter. Resin could be almost completely freed from ethereal oil at 100° to 110°, and it was only in the case of oils prone to vx1dation, such as oil of eloves, that the residual resin was somewhat heavier than was expected. (See also $ 146.) Drying oils would, of course, increase very appreciably im weight. The evaporation and heating would have to be conducted in an atmosphere of carbonic acid ($ 9). The following experiment will serve as an example of the estimation of ethereal oil in a vegetable substance :! Five grams of savin leaves were finely powdered and digested with 25 ce. of petroleum spirit; 1 ce. of the solution was eva- porated. The residue weighed 00265 gram (corr.), which de- creased to 0:0175 gram on heating to 110°. 1 ce. contained, therefore, 0'009 gram ethereal oil and 0°0175 gram resin, or 4:5 per cent. of ethereal oil and 875 per cent. of resin. $ 139. Separation of Volatile Acids —Angelie acid melts at 45° and boils at 185° ; methyl-erotonic acid at 65° and 198° ; erotonie acid, 16° and 160°5° ; capric, 30° and 268° to 270° ; capıylic, 16° to 16°5° and 236° to 237° ; enanthic boils at 223° to 224° ; caproic, 204° to 206° ; valerianic at 175° ; trimethyl acetie, 163°7° to 163°8° (melts at 35°3° to 35°5°); butyrice at 163°; isobutyrie, 154°; propionic, 140° ; acetic, 118° (solidifies at 16°7°); formic, 105”. This difference in the boiling points of fat-acids permits of their separation from one another by fractional distillation. Fractional precipitation by salts of silver, ete., may also be found useful in separating several of the foregoing volatile acids from one another; certain differences in the solubility of the salts can also sometimes be turned to account. Isobutyrie acid, for instance, may be separated by the former method, whilst the sparing solubility of the silver salt (1 in 100) enables us to isolate acrylic, butyric, acetic acid, et. The barium, calcium, and lead salts of some of the acids may be similarly employed ; thus the barium salt of caprylie acid is soluble in 164 parts of cold water 2 formate of caleium is insoluble in absolute alcohol ; the lead salt dissolves in 65 parts of water, whilst mercurous formate requires 500 parts at the ordinary temperature. Basic formate of lead obtained ’ See Osse’s work previously referred to. * For the estimation of valerianic acid, see Zavatti and Sestini, Zeitschr. f. anal. Chemie, viii. 388, 1869. 120 ETHEREAL OILS. by heating formic acid with oxide of lead is insoluble in alcohol? whilst basic acetate of lead prepared in a similar way is soluble (the heating should be continued until the reaction is alkaline, but not longer, as otherwise an acetate insoluble in alcohol might be produced). Basic butyrate of lead is also soluble in alcohol, but both the neutral and basic salt are greasy and sparingly soluble in cold water. The same is the case with the ferric compound obtained by precipitating an alkaline butyrate with a ferrie salt (avoiding an excess). (See also $ 34.) $ 140. Identification. —The saturating power of a fatty acid, & knowledge of which may be of assistance in identifying it, can be ‚ascertained by titration with normal soda solution, or by esti- mating the sodium, barium, lead or silver contained in the corre- sponding salts. Im certain cases a determination of the water of erystallization may prove useful. By distilling the sodium salts with concentrated sulphurie acid and absolute aleohol, the ethyl-salts of the acids may be prepared ; they are not unfrequently of characteristie odour (acetate, buty- rate, valerianate of ethyl, etc.), by which, as also by their boiling points, they may sometimes be identified. $ 141. Optical Tests ; Solubility in Aleohol.—For information with regard to the optical testing of volatile oils see Buignet,? Franck,? Flückiger,* and Symes.’ I have ascertained that alcohol must possess the following strengths to be miscible with certain ethereal oils in every propor- tion : oil of turpentine, 96 per cent. ; fir, 96 per cent. ; Juniper, 95 per cent. ; savin, 92 per cent. ; lemons, 97 to 98 per cent. ; ber- gamot, 88 per cent. ; bitter orange, 98 per cent. : caraway, 88 per cent. ; peppermint, 86 to 87 per cent. ; oleum menth& crispae, 86 per cent. ; lavender, 88 per cent. ; rosemary, 82 per cent. ; sweet marjoram, 82 per cent. ; cajeput, 91 per cent. ; sage, 85 per cent. ; cloves, 74 per cent. ; cinnamon, 78 per cent. ; cubebs, 90 per cent. ;_ fennel, 93 per cent. ; anise and rose, 93t0 94 per cent. ; balm, 90 1 Barfoed, Lehrbuch der organischen qual. Analyse,’ Kopenhagen, 1880. 2 Journ. de Pharm. et de Chim, [3], xl. 252, 1862 (Amer. Journ. Pharm. xxxiv. 140). 3N. Jahrb. f. Pharm. xxvii. 131; xxix. 28. See also Mierzinski, * Die Fabrik. äth. Oele,’ Berlin, 1872, and Flückiger’s ‘Pharm. Chemie,’ Berlin, 1879, where the specific gravities of certain ethereal oils will also be found. 4 Archiv d. Pharm. [3], x. 193, 1877 (Amer. Journ. Pharm. Ixxvii. 309). 5 Pharm. Journ. and Trans. [3], x. 207. $ 142. COLOUR-REACTIONS. 121 per cent. These figures are true for fresh oils only, and for tem- peratures ranging from 20° to 22°.! I found the following proportions of weaker alcohol necessary to form clear mixtures with the foregoing oils: Vols. Strength of Spirit. Oil of Cinnamon . F .3 of 65 per cent. (Tralles). „ Cloves ET 26 00 m = „ Sage. s al. 68 » „» „ Cajeput . zn 00 „ » ‚„ Marjoram . el Te 35 >> „» Rosemary . ee tie) 5 A „, Lavender . BoD 08 er ba »» Mentha crispa WORT 5 08 er 5 »» Peppermint a 0 „ » „ Caraway a0ESE 84 s; nr »» Bitter orange en 94 r s »» Bergamot . als Ze >= 3% »» Lemon (dist.) 4:07. 9 55 Mr 55 » (pressed) DS 9 e 5% ‚„ Savin 1 el 5 ss „,; Juniper 3. 000.,,.08 ar 5,5 »» Turpentine Sn ° » Remen » : „ 85 (at 21° ) „» Anise 2 ; 0m SH (ab Leo C,) D Ne} $ 142. Colour-reactions. —I have observed the following colour- reactions with certain ethereal oils :? Solution of bromine in chloroform (1 in 20), in the proportion of 10 to 15 drops to one of oil, gives colourless mixtures with oils of turpentine, caraway, lemon, coriander and cardamoms ; yellow with bergamot, bitter orange and neroli ; slowly turning green with cloves, ginger, lavender, cajeput, cascarilla ; slowly turning greemish- blue with ol. menth. crisp., oils of juniper, pepper and galangal ; greenish-brown or brown with sweet marjoram, dill, cummin and valerian ; a more or less fine rose, red, or reddish-violet tint is gradually produced by rosemary, fennel, anise, star-anise, cinna- mon, nutmeg, thyme, peppermint, myırh and parsley ; brownish- violet with mace; blue or bluish-violet with cubebs, copaiba, amomum, laurel, Kata wood and sweet flag; orange with oil of worm-seed, oil of cedar-wood ; and with camphor. U N. Repert. f. Pharm. xxii. 1, 1872; Pharm. Journ. and Trans. [3], vi. 541 et sey. See also Godeffroy und Ledermann, Zeitschr. d. allgem. oesterr. Apotheker Ver. xv. 381 ei seq. ; Jahresb. f. Pharm. 394, 1877 ” Pharm. Journ. and Trans. [3], vi. 681; Archiv d. Pharm. [3], xii. 289. Dee also Hager, Pharm. Centralblatt, 137, 169, 195, 1870 ; and Flückiger, Schweiz, Wochenschr. f. Pharm. 261, 1870. 122 ETHEREAL OILS. Impure Chloral Hydrate! (2 drops to 1 of oil), resembles the fore- going reagent in the colouration it produces with many oils. It differs, however, in its behaviour to oil of lemon and bergamot, with which it assumes a reddish colour ; cloves, which turns red on warming ; mace (fine rose-red), pepper (reddish-violet), copaiba (dark-green), valerian (greenish), cummin (fine green), einnamon (green, with violet margin), and myrrh (reddish-violet). Alcoholic hydrochloric acid varies in its action with the amount of acid it contains. A dilute solution is to be preferred, as the colourations appear more slowly, but are purer. Dilute aleoholie hydrochloric acid in the proportion of 15 to 20 drops to 1 of oil yields colourless mixtures with oil of turpentine, caraway, coriander, cardamoms (conc. acid, cherry-red), cloves, rosemary (cone. acid, deep cherry-red); yellow mixtures with bergamot (cone, acid, orange to olive-green), mace (conc. acid, reddish-brown), dill (conc. acid, cherry-red), bitter orange, cummin (conc. acid, deep violet) ; brownish-red with oils of cascarilla, lavender, sweet marjoram, worm-seed, juniper (conc. acid, red) ; rose to deep red or reddish-violet with oils of cubebs, pepper, copaiba, cedar wood, ein- namon, nutmeg, thyme, laurel, sweet-flag and myrrh ; red, turning blue, with oil of peppermint. Concentrated sulphuric acid (2 or 3 dropsto 1 of oil) assumes with most oils a yellow colour, turning brown, and frequently passing finally to a fine red. The latter colouration is observable with oils of caraway, mentha crispa, sweet marjoram, star-anise, mace, dill, juniper, cubebs, copaiba, sage, winter-green, lavender, amomum, cascarilla, nutmeg, thyme, sandal-wood, peppermint, myrrh, and parsley. Oils of cardamoms, cloves, fennel, anise, ‘cajeput and laurel produce a violet, einnamon a green and blue colouration. If a drop of the oil is mixed with 1 ce. of chloroform and 2 drops of conc. sulphurie acid added, similar colours are produced? and imparted to the chloroform. ! Jehn was the first to observe that this reagent produced a currant-red colour with oil of peppermint. Its use is, however, open to objection, as it is not yet known what impurity causes the colouration, and it is therefore impos- sible to prepare a reagent of constant composition. If 100 cc. of alcohol are saturated with chlorine, mixed with sulphuric acid (after partialiy separating the hydrochlorie acid by evaporation) and the resulting metachloral distilled, a very satisfactory reagent will be obtained, but its activity diminishes on keeping. ® But not if petroleum spirit is used instead of chloroform. $ 142. COLOUR-REACTIONS. 123 Fröhde’s Reagent! resembles sulphuric acid in its action ; but the for coriamyrtin compare $ 155; for pittosporin see v. Müller ;* for sumaderin see de Vrij.? Colocynthin can be obtained in yellowish erystals which dissolve: in conc. sulphuric acid with the gradual production of a fine red colour ; Fröhde’s reagent produces a cherry-red. It is extremely bitter, easily soluble in water and alcohol, but insoluble in ether. Benzene ($ 55), or better, chloroform or amylic alcohol, extracts it from aqueous solution ; it is precipitated by basie acetate of lead and by tannin. Bryonin is also precipitated by the latter reagent.® For ononin, which gradually assumes a cherry-red colour with conc. sulphuric acid, see Hlasiwetz.? Apiin erystallizes in shining silky needles soluble in hot water: or, more easily, in hot alcohol. Ether does not dissolve it. Ferrous sulphate colours the aqueous solution blood-red. Both alcoholic and aqueous solutions gelatinize on cooling. Im dilute alkalies apiin dissolves with yellow colouration. For datiscin, which is also coloured yellow by alkalies, see Braconnot® and Stenhouse.? Ferric chloride precipitates it green ; 1 For a number of other glucosides and allied substances (argyrscin, aphrodsscin, etc.) discovered by Rochleder in horse-chestnuts, see Journ. f. pract. Chem. Ixxxvii. 26, 1863 (Amer. Journ. Pharm. xxxv. 290). ®2 For the nearly allied ligustrin, see Kromayer, Archiv d. Pharm. cv. 9 1861 ; for syringopierin (easily soluble in water), ibid. cix. 26, 1862. ; 3 N. Jahrb. f. Pharm. vü. 1, 1857 ; xiii. 281, 1860. +“ The Organic Constituents of Plants,’ Melbourne, 1878. 5 Chem. Centralblatt, 92, 1859 ; Jahresb. f. Pharm. 208, 1872. See Blume, Amer. Journ. Pharm. xxxi. 342. $ N. Jahrb. f. Pharm. ix. 65, 217, 1859 (Amer. Journ. Pharm. xxxi. 249). ’ Chem. Centralblatt, 449, 470, 1855. 8 Annales de Chimie et de Physique [2], iii. 277, 1816. 9 Annal. d. Chem. und Pharm. xeviii. 166, 1856 (Journ. Chem. Soc. ix, 226). For helianthice acid compare Ludwig und Kromayer, Archiv d. Pharm, [2], xeix. 1, 1848 (Amer, Journ. Pharm. xxxii. 135). $ 167. HESPERIDIN, ETC. 173 acetate of lead, yellow. Zander! has recently found a glucoside allied to datisein in the seeds of Xanthium strumarium, For physalin, which can easily be extracted by shaking with chlorc- form ($ 55), see Dessaignes and Chautard > for dulcamarin, see Geissler.? The latter is soluble in acetic ether, insoluble in ether, chloroform, bisulphide of carbon, and benzene. It is precipitated by tannin, and by basic acetate of lead. Conc. sulphurie acid dissolves it with red colouration passing to rose; with alkalies it forms reddish-brown solutions. Hesperidin shows a disposition to form sphero-erystals. It is sparingly soluble in water and cold alcohol, freely in warm alcohol and acetic acid, but insoluble in ether. Ferric chloride colours it brownish-red ;* conc. sulphurie acid gradually bright red (limonin the same). Acetate of lead produces no preeipitate. 1 a solution in dilute potash is evaporated to dryness, the residue is coloured red, passing to violet when warmed with excess of dilute sulphurie acid. Hesperidin can be recognised under the microscope as spharo-erystals soluble in warm alcohol. Croein (polychroite) forms a dark red powder sparingly soluble in ether and water, more easily in alcohol. Conc. sulphurie acid colours it blue. Dilute acids resolve it into glucose and crocetin (insoluble in water), a saffron-like odour being developed during the decomposition. Basic acetate of lead precipitates crocin.? Glyeyrrhizin® is deposited from glacial acetic acid in spharo- erystalline masses of prismatic needles. After purification with acetie acid it is almost insoluble in water (forming a jelly with it), but may nevertheless be extracted (in combination with bases) from liquorice-root by that menstruum. It contains nitrogen, is sparingly soluble in absolute, more easily in boiling 90 per cent. ! The so-called smilacin was also formerly regarded as allied to saponin, but the researches of Flückiger! have shown that under this designation a mixture of substances has been described, the prineipal constituent of which was named parillin. This body stands in close relation to sapogenin, the decomposition-product of saponin ; and as the latter is contained in sarsaparilla,? it is probable that parillin is produced from it during the life of the plant. According to Flückiger, parillin is not soluble in cold water to any appreciable extent, but dissolves in 20 parts of boiling. It is taken up by spirit of sp. gr. 0'83 more easily than by stronger or weaker alcohol.? Its reaction with conc. sulphurie acid re- sembles that of saponin. Boiled with 10 per cent. sulphuric acid it decomposes into sugar and parigenin, with production of a green fluorescence. A similar fluorescence is also observed when hydrochloric acid gas acts upon a solution in a mixture of chloro- form and alcohol. Sapogenin resembles parillin in most of its properties. Roch- leder is of opinion that it still retains a little sugar, and is there- fore really the result of an incomplete decomposition of saponin. The violet colouration gradually produced when sapogenin is dissolved in conc. sulphurie acid serves to distinguish the body from digitoresin, which, according to Schmiedeberg, yields a yellow solution. (See $ 155.) Indican may also be mentioned here, as, although it is not a substance that can be unconditionally ranked as a glucoside, it may nevertheless be compared with them as regards its constitu- tion. By the decomposition of indican indigo-blue is produced, together with a kind of sugar called indigluein. I leave it, how- ever, an open question whether the formation of indigo-blue is preceded by that of indigo-white, which, it is true, readily yields‘ that substance by absorption of oxygen. Indican appears to occur in many plants (leaves, ete.), but to undergo a partial decomposition when they are slowly dried, and the black or blue 1 Compare Flückiger and Hanbury, ‘* Pharmacographia,' 646. 2 Otten, ‘ Histiol. Unters. der Sarsaparillen, Diss. Dorpat, 1876. Otten estimated the saponin by the methods given in $ 78. 3 Archiv d. Pharm. [3], x. 535, 1877 (Pharm, Journ. and Trans. [3], viil, 488). $ 168. OTHER BITTER PRINCIPLES. 175 eolouration of the leaves produced thereby would arouse a sus- pieion of its presence. Cold spirit extracts indican ; the solution is best evaporated in a current of dry air at the ordinary temperature. Foreign bodies may be removed from the aqueous solution by shaking it with freshly precipitated hydrate of copper, but the copper that simultaneously passes into solution must be subse- quently removed by sulphuretted hydrogen. "The aqueous solution must also be evaporated at the ordinary temperature, the residue dissolved in cold alcohol, and the indican precipitated by ether. Dilute acids decompose this unstable body, as above described, with production of indigo-blue. The latter is characterized by its insolubility in water, aleohol, and ether and solubility in carbolic and fuming sulphuric acids. It can be sublimed, and yields indigo-white (soluble in water) when boiled with glucose and an alkali. Advantage might be taken of the latter property testing for indican in dried vegetable substances. The residue of the material after exhaustion with water might be boiled with an alkali and glucose ; from the solution thus obtained the indigo-blue would be again precipi- tated by passing a current of air through it. $ 168. The following bitter principles have not as yet been shown to be glucosides; but they are likewise sparingly soluble in ether, more freely in alcohol: Antiarin,! aristolochia-bitter,? calendulin > (gelatinizes with water), californin* (appears to be a mixture of alka- loids, of which loturin, which is strongly fluorescent in acid solution, is especially interesting) ; carapin,? erategin,® cusparin? (coloured green by nitrie acid, red by mercurous nitrate) ; quinovin® (quin- ovic acid, obtained by boiling quinovin or quinova-bitter with acids, is said to resemble cholic acid in gradually turning red with 1 See de Vrij and Ludwig, Zeitschr. d. oesterr. Apoth. Ver. 92, 1868 (Amer. Journ. Pharm. xxxv. 474). ” See Walz, Jahrb. f. Pharm. xxvi. 73. Gmelin’s ‘Organic Chemistry.’ 3 See Stoltze, Ber. Jahrb, f. Pharm. 1820. * See Mettenheimer, N. Jahrb. f. Pharm. i. 341, 1870. Hesse, Ber, d. d. chem. Ges. xi. 1542, 1878 (Journ. Chem. Soc. xxxvi. 73). ° See Caventou, Vierteljahresschr. f. pract. Pharm. x. 422, 1861 (Amer, Journ. Pharm. xxxi. 231). $ See Leroy, Journ. de Chim. med. xvii. 3. 7 See Saladin, ibid. ix. 388 (Amer. Journ. Pharm. v. 346). ® Compare Gmelin, “Handbook of Organic Chemistry.’ Staeder’s method of estimating quinovic acid in certain einchona barks (N. Tijdschr. voor de ne in Nederl, 152, 1878) was pronounced unsatisfactory by de Vrij (ibid. 306). 176 ALOINS. sulphurie acid and sugar) ; eniein! (is said to dissolve green in conc. hydrochloric, red in sulphuric acid. It can be extracted by shaking with benzene ($ 55), but is partially precipitated from aqueous solution by basic acetate of lead) ; N 2 lactuein and its allies,? linin,* lupinin3 mudarin,s olivil,? querein® (very slightly soluble in absolute alcohol) ; sparattospermin.? $ 169. Aloins. —There is another group of non-glucosidal bitter principles to which I should like to direct attention ; viz., that of the aloins—a series of closely allied but not identical chemical in- dividua. All the members of the group are soluble in water and alcohol, sparingly only in ether ; but it must be observed that the separate aloins show notable differences in their behaviour to water. That obtained from Natal aloes is the most difficultly soluble, whilst the aloin of Cape aloes, which is possibly isomeric with nataloin, is comparatively freely dissolved.!° All the aloins can be obtained in yellow cerystals, but show a great disposition to form supersaturated aqueous solutions in which, perhaps, they exist in an amorphous state and free from water of cıystallization. From such solutions the aloin can be 1 See Nativelle, Journ. de Chim. med. xxi. 69, and Scribe,-Comptes rendus, xv. 802. See also my article on the detection of foreign bitters in beer in the . Archiv d. Pharm. [3], iv. 293, 1874; also 'Kubicki, ‘Beitr. zur Ermittel. fremder Bitterstoffe im Biere,’ Diss. Dorpat, 1874 (Pharm. Journ. and Trans. [3], v. 566, 1875), and Jundzill, ‘Ueber die Ermittel. einiger Bitterstoffe im Biere,’ Diss. Dorpat, 1873. 2 See Müller, Archiv d. Pharm. [1], xxii. 29, 1828. 3 Compare Ludwig and Kromayer, Archiv d. Pharm. exi. 1, 1862; also Kromayer, ‘ Bitter stoffe,” 4 See Schroeder, N. Repert. f. a. 2.11, 1804, 5 Compare Landerer, ibid. i. 446, 1854. This lupinin must not be con- founded with the glucoside of the same name discovered by Schulze and Barbieri in 1878. Compare Ber. d. d. chem. Ges. xi. 2200 (Journ. Chem. Soc. xxxvi. 467). 6 Compare Duncan, Phil. Mag. x. 465. 7 Compare Pelletier, Annal. de Chim. et de Phy sique, iii. 105 ; and Sobrero, - N, Jahrb. f. Pharm, iii. 286, 1855 8 See Gerber, Archiv d. Pharm. En 167, 1831. 9 See Peckolt, Zeitschr. d. allgemeinen oester. Apoth. Ver. 133, 1878 (Pharm. Journ. and Trans. [3], ix. 162, 1878). 10 Accordingto Treumann’s researches (‘ Beitr. z. Kenntniss der Aloe, ihber Dorpat, 1880) the following are the formulze of the various aloins (containing water of erystallization) caleulated to the same number of atoms of oxygen. Barbadoes aloin=(C,sH,3059 6H,50 ; Cape aloin=C,;H,sO5,, 6H,0 ; Socotra aloin—=C,,H;s050 6H,0 ; Natal ER C,,H,;050; Zanzibar aloin=0,,H,050 6-7H,0 ; Curagao aldi C,H, 020, 6H,0. See also Flückiger, Schweiz, Wochäunahe, £. Pharm. 331, 1870 ; Pharm. Journ, and Trans. [3], ii. 193, 1871. $ 169. ALOINS. 177 gradually obtained by diffusion, but it is often long before they deposit erystals (most easily obtained from Natal aloes). Ferric chloride colours them, without exception, greenish-black (Natal aloin very slowly) ; they are all gradually preeipitated by basic acetate of lead ; perchloride of platinum colours Barbadoes and Curacao aloin by degrees red to violet, Socotra and Cape aloin greenish-brown, Natal aloin yellowish-brown ; chloride of gold pro- duces a moreor less fine raspberry-red, passing generally into violet; with strong hydrochlorie acid, Natal aloin alone becomes violet; mereurous nitrate colours Barbadoes and Curacao aloin reddish. All the aloins are preeipitated from aqueous solution by bromine- water, in the form of sparingly soluble brominated compounds, which contain frequently, but not invariably, 40 to 44 per cent. of bromine. The opinion expressed inmy ‘Chemische Werthbestim- mung starkwirkender Droguen,’ that these bromine-preeipitates might be used in determining the value of the different varieties of ‚ aloes, was based upon some experiments of Kondracki’s;! but since Treumann has shown that one and the same aloin can yield more than one substitution-product, I have been shaken in this opinion. The applicability of another method of estimating the value of an aloes by ascertaining how much tannin is necessary to precipitate and redissolve one of the constituents, has also been rendered doubtful. I was convinced that this body precipitable by tannin was a decomposition-product of aloin, or possibly an amorphous modification, and that it acted directly as a purgative; Kondracki’s experiments confirmed this supposition by showing that the more active an aloes was, the greater was the amount of tannin solu- tion required in titrating. But as more recent experiments have proved that the aloins themselves when taken in sufficient quantity have a purgative action (whether direct or indirect, I am unable to say), and the attempts to compare the amount of aloin in an aloes with that of the substance precipitated by tannin have not met with success, I feel myself compelled to retract for the present the statements made in my ‘ Werthbestimmung ’ on this subject. The aloin is accompanied in aloes by a resinous substance which does not dissolve when the aloes is treated with about 10 parts of water, but which is soluble in concentrated aqueous aloin-solutions, in hot water, and in alcohol. Another body, probably non-pur- gative, also oceurs in dried aloe-juice ; it is freely soluble in cold ! Beitr, z. Kenntniss der Aloe, Diss. Dorpat, 1874. 178 ALKALOIDS. water, and is possibly an oxyaloin. Bromine does not appear to preeipitate it from aqueous solutions. $ 170. Carthamin, etc. —Some substances, more freely soluble in alcohol than in ether, and characterized by their yellow colour, have been already mentioned in $ 152, in connection with quercitrin (rulin, robinin, luteolin, ete.), and whilst referring to them here, I will also allude to carthamin, the colouring matter of safllower.! It has been obtained in the form of an amorphous powder, of an orange-green colour and metallic lustre. It is sparingly dissolved by water, but easily by aqueous alkalies and alcohol ; from alkaline solution it is preeipitated by acids. It dissolves in ether, and stains silk rose- or cherry-red. ALKALOIDS. s 171. Colour-reaetions. —The following reagents may be recom- mended for producing colour-reactions with alkaloids: Pure sulphurie acid ; sulphuric acid, containing a little nitrie acid (1 in 200) ; sulphuric acid, containing 0°01 gram of molybdate of soda in each cc. (Fröhde’s reagent) ; sulphuric acid and sugar ; sulphurie acid and bichromate of potash ; nitrie acid (sp. gr. 1'3) ; conc. hydrochlorie acid ; ferrie chloride. The reactions are best ob- served when a few drops of a solution (in alcohol, ether, chloro- form, etc.) are allowed to evaporate in a small dish and a drop or two of the reagent added to the residue. In testing with sul- phurie acid and sugar, it is generally better to mix the alkaloid as intimately as possible with 5 parts of sugar and add the sulphurie acid to the mixture. Delphinoidine should be mixed with as con- gentrated a solution of sugar as possible before the addition of sul- phurie acid. If bichromate of potash and sulphurie acid are to be used in combination, it is advisable to dissolve the alkaloid in the acid and drop a erystal of bichromate into the solution. Sulphurie acid and nitrate of potash may be employed in the same way in place of the mixed sulphurie and nitrie acids. Ferrie chloride should be used in aqueous solution, and be as neutral as possible. ? Some of these reactions might be used in testing for alkaloids microchemically. The following table contains a few of the re- actions of the more important alkaloids. 1 Compare Schlieper, Annalen der Chemie und Pharm. lviüi. 357, 1846. 2 Allthese reactions are described at greater length in my ‘Ermittel. d. Gifte.’ 179 171. REACTIONS. S -dnd og soyena -p91-Auaoyd ANOLOD UMLIOD FO OPIXO pur ppedLınydmms onrq doop yuadvad sIpygQLT Ur uorl -N[OS 944 SANOJOO PIOR DLIOTTEOAPAU "DUO,) "99T0TA PIoR drınyd } -[ns ur uorm[os 944 SINOJOD PurwoAg "pO9rBIOABA9 USUAM HNPIs9A HuıfrgsA.r ® SOAB9T UOLNNJOS PIOIR DLIOTUPOAPAU OUL ‘ourumb oyrT "yseyod Aq pa P9amoJod ST ONPISOL 9uF ‘Aem® opeF 0} P9nole st Fog@g ur uormfos oyF 04 oayodyes Zumppe fq paonpoad moJoa anq oyF FI "UOLFE.IMOTOD PaIL ULM P9sodwonap £jprdei st pfo3 Jo opnıoyo yyın 'ydd ayL DAodR 1 se PIYBIA UOUA SSOLINOJOD uU ) "uunıs -sejod Fo OpIUwÄopLLIOF Pu vIuoWwue pm umoilg-poı wruowuw Aq U99ALS P3ANO[0O9 ST UOIMIOS A9EAM-HULIOIUD OUL "TOOL UT OTANTOSUT ST OPIPOT LMILDIW-OISSTIOA um oyeyıdıoaad oUL wIuoruu Äcq PO. 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SUTWIILN ourydaıomt ouropoyI* OUTA.IOP "aIoIvMIV 7 ss 172, 173. SUBLIMATION, ETC. 181 $ 172. Other Tests. —For information concerning optical tests for alkaloids, see Buignet.! Upon polarization ($ 185), in particular, see Hesse.? For the absorption spectra observable in colour-re- actions of alkaloids, see Meyer”? and Poehl.? The temperature at which alkaloids sublime has been deter- mined by Armstrong, in an apparatus similar to that described in $ 17 for ascertaining the melting-point of fats,. The alkaloid is placed ona coverslip, to which a glass ring 4 to 3 inch high is cemented, and on which a second coverslip is Ei As soon as a cloud is observed on the latter, the temperature is noted. The sublimate is subsequently examined microscopically as to its erystalline or amorphous character. Mercury or easily fusible alloys may be used to heat the alkaloid. For the appearances observable during the microsublimation of alkaloids, see Helwig, Guy, Waddington, and others.’ The erystalline form of alkaloids has been closely investigated by Erhard.® $ 173. Platinum and Gold-salt. —The following list contains the percentage of platinum and gold in the double chlorides of those metals with some of the more important alkaloids (dried at 100°). Double Salts of Gold. Platinum. Atropine e E 31°37 ‘ 2 == Aconitine & £ 22°06 : 5 — Amanitine . N 4423 . ; — Berberine R s 29-16 ; e al Brucine i R - B . 16°52 1 Journ. de Pharm. et de Chim. [3], xl. 252, 1862 (Amer. Journ. Pharm. xxiv. 140). ® Annal. d. Chem. und Pharm. elxxvi. 89, 1875 (Pharm. Journ. and Trans. [3], vii. 191), and exeii. 161, 1878. See also Oudemans, ibid. elxxxii. 33, 1877 (Year-book Pharm. 75, 1878); Arch. Neerland. des Sciences exactes et naturelles, x. 193, 1875; and amongst older works that in particular of Bouchardat, Annales de Chimie et de Physique [3], ix. 213. See also Poehl’s paper subsequently quoted. 3 Archiv d..Pharm. [3], xiüi. 413, 1878. * Pharm. Zeitschr. f. Russland, 353, 1876. > Compare Helwig, ‘Das Mikroskop in der Toxicologie,’ Mainz ; Guy; Pharm, Journ. and Trans. [2], viii. 718; ix. 10, 58, ete. ; Waddington, ibid. [2], ix. 266, 409 ; Stoddart, ibid. 173; Brady, ibid. 234; Ellwood, ibid. [2], 152 Dedkewiels, Brit. Rev. Ixxxi. 262. 6 N. Jahrb. f. Pharm. xxv. 129, etc. ; xxvi. 9, ete., 1866. Amongst the older works are: Hühnefeld’s “Chemie der Rechtspflege,’ Berlin, 1823; Anderson, Chem. Centralblatt, 591, 1848; Taylor, ‘On Poisons ;’” Guy, ‘ Prineiples of Forensic Medicine ;’ Brand et Chaudd, ‘Me&decine legale,’ Paris, 1853. ’ 182 ALKALOIDS. Double satt of Gold. Platinum. Caffeine A F 37-02 1 e 2458 Cinchonine . i — 3 Ä 2736 Cinchonidine . e — 5 . 27°87 Codeine R a = 3 : 19271 Coniine 5 A — R D 2938 Curarine 4 _ x „.* BQubb Delphinine . \ 26°7 2 ; — Delphinoidine 3 29-0 : Ä 158 Emetine 2 ä — i A 297 Hyoscyamine - 34°6 - ‘ — Morphine . ; - A s 1952 Muscarine . z 43-01 a R — Narcotine 2 A — L . 4157-159 Narceine A : — u, 1452 Nicotine . A — . A 3425 Papaverine . 3 == - b 17'82 Pilocarpine . > 35°5 - . 23°6-25°2 Piperine . — ; - A, Quinidine . , 40:04 e R 2738 Quinine ; . 40:00 x . 2626 Strychnine . : 2915 ; e 18°16 Thebaine : & _— - E 1871 Theobromine . . — : . 2555 Veratrine . i 21°01 s E = $ 174. Estimation of Alkaloids..—In estimating the alkaloid in leaves or easily pulverizable stalks, it will frequently be found practicable to exhaust the powdered substance with spirit, evaporate the tincture, and extract the residue with acidulated water. The solution thus obtained may then be titrated with potassio-mereuric iodide, as directed in $ 65. But if the material contains much starch, or is difficult to powder (as, for instance, aconite root), it is better to allow it to soak in about twice its weight of dilute sulphurie acid (1 in 30) before extracting with alcohol, as, otherwise, larger fragments of the substance are not uniformly penetrated by the spirit. In estimating atropine, the drop-test (that is, the addition of a drop of the preeipitating solution to a filtered drop of the liquid to be preeipitated) cannot be used. It will be found advanta- geous to add at once sufficient of the reagent to precipitate the greater part of the alkaloid ; after standing several hours, until the supernatant liquid has become clear, more of the reagent may be added, and so on as long as a precipitate is produced. The liquid clears more rapidly as the end is approached, till at last an interval of five to ten minutes is suflicient. Atropine may also be estimated gravimetrically by adding $ 174. ESTIMATION OF STRYCHNINE, ETC. 183 excess of potassio-mereuric iodide, dissolving the precipitate in aleohol of 90 to 95 per cent., evaporating the filtered solution, and weighing the residue, which contains 40°9 per cent. of atropine. For hyoscyamine the same precautions are necessary as for atropine.! In estimating coniine gravimetrically with potassio-mercuric iodide, I obtained results that were far below the truth; the compound preeipitated is somewhat freely soluble. (See also s$ 175, 180.) f Nux Vomica and St. Ignatius’ beans contain two alkaloids, strychnine and brucine, which differ in the intensity, at least, of their action on animals, and this fact must not be lost sight of in determining the value of those drugs by titration with potassio- mercuric iodide. I have therefore proposed the following indireet method of determining both alkaloids: ? 15 to 30 grams of the finely rasped seeds are exhausted by boil- ing three times in succession with dilute sulphuric acid (1 in 50), pressing the residue each time. The decoctions are united (about 700 ce.), nearly (but not quite) neutralizel with magnesia and evaporated to a syrup in the water-bath. To the residue 24 times its volume of 90 per cent. spirit is added, and after standing, the preeipitated mucilage is filtered off and washed. The filtrate and washings are evaporated to about 30 to 50 ce. and, whilst still acid, well shaken with chloroform. The chloro- form is then separated, the aqueous liquid made alkaline with ammonia, and the agitation with chloroform repeated as long as any alkaloid is removed. The alkaloidal residue obtained by evaporating the chloroformie solution is dried, weighed and dis- solved in hydrochloric acid; the excess of acid is removed by eva- poration, and the solution titrated with potassio-mercurie iodide. The weight of strychnine can be caleulated from the expression »=5'566 (00197 xc—m) and that of brucine from y= 6'566 (m—0:0157 x c), where c is the number of ce. of reagent used and m the weight of the mixed alkaloids. It is still better to weigh the hydrochlorates of the alkaloids and caleulate the strychnine salt from the expression x=6'1733 (0'02152xc-m), and the " Compare my ‘ Werthbestimmung,’ 32, and Thorey on the ‘ Distribution of Nitrogen in black and white henbane,’ Diss. Dorpat, 1869, and Pharm, Zeitschr. f. Russland, 265, 333, 1865 (Pharm. Journ. and Trans. [3], xii. 874). ” See my “Werthbestimmung,’ 64. Compare also Pharm. Zeitschr. f. Russ- land, 233, 1866. 184 ALKALOIDS. brucine salt from y=7'1733 (m 0.91852 x.c), c being the same as in the previous expressions and m denoting the weight of the mixed hydrochlorates. Titration of morphine and narcotine with potassio-mercuric iodide serves only as a check on the weight of the alkaloids after isolation (SS 182, 187), The total alkaloid in opium cannot be estimated Toluineiieele: with that reagent. For a method of examining chelidonium compare $ $ 65 and my ‘ Werthbestimmung,’ p. 98. The presence in cevadilla seeds of three alkaloids, all of which act upon potassio-mereuric iodide, renders it impossible to do more with this reagent than compare the extracts of two or more different samples of seeds with one another. If an approximate separation of the three alkaloids is desired, it must be remembered that, according to the investigations of Weigelin,? all three are re- moved together by shaking with chloroform; that sabadilline is almost insoluble in ether, but is dissolved by 150 parts of water at the ordinary temperature ; that sabatrine is freely soluble in ether and soluble in 40 parts of cold water; and finally that veratrine is said to be taken up by 10 parts of ether and 1,000 of cold water. The researches of Harnack and Witkowski have proved ® that the calabar bean also contains two alkaloids (calabarine and physostigmine), differing from one another in physiological action. For this reason the estimation of the total alkaloid by titration with potassio-mereuric iodide has only a limited value, but the alkaloids might possibly be separated, and estimated gravimetri- cally, as the calabarine preeipitate is insoluble in aleohol whilst that produced by physostigmine is soluble. $ 175. Conüne, pilocarpine, ete.—Zinoffsky has shown that coniine can be accurately estimated by phosphomolybdie acid in solutions free from ammoniacal salts.* The strength of the reagent was such that 1 cc. precipitated 0:05 gram of coniine. „I Compare E. Masing, Archiv d. Pharm. [3], ix. 310, 1876 (Journ. Chem. Bde xxxii. 367). 2 Compare Weigelin, ‘ Unters. über die Alkaloide der Sabadillsamen,’ Diss. Dorpat, 1871 (Journ. Chem. Soc. xxv. 828). See also P. G. A. Masing, “Beitr. z. gerichtl. chem. Nachw. des Strychn ins u. Veratrins,' Diss. Dorpat, ee Archiv f. exper. Patholog. und Pharmacol, v. 401, 1876 (Pharm. Journ, and Trans. [3], viii. 3). 4 Compare Schmiedeberg, Zeitschr. f. phys. Chem. i. 206; Ritthausen, Archiv f. die ges. Phys. xvi. 301 (Journ. Chem. Soc. xxxiv. 518). 4 Loc. cit. ® *Beitr. z. quant. Eiweissbest. Diss. Dorpat, 1870. 6 ‘ Beitr. z. Albuminometrie und z. Kenntniss d. Tanninverb. d. Albuminate. Diss. Dorpat, 1872. 7 Einige Methoden z. Werthbest d. Milch. Diss. Dorpat, 1873. $ 229, 230. ESTIMATION. 937 means of the tannin reagent mentioned in $ 95, and Cramer- Dolmatow has found that extracts from one and the same plant yield concordant results when titrated with the same reagent. It must be left, however, for further experiments to show what veget- able albuminoids can be estimated in this way. $ 230. Estimation continued.— A gravimetric estimation with tanmım will generally yield higher results than can be obtained by coagı- lation ($ 94). The source of the difference is to be looked for partly in the deficiencies of the latter method, and partly in the fact that a number of albuminous substances soluble in water are not coagulated by boiling with dilute acetice acid, but are nevertheless precipitated by tannin. For this reason the results obtained by the tannin-method will generally agree better with those yielded by precipitation with alcohol. Nevertheless, Idonotrecommend the omission of the estimation by coagulation, for if the difference is considerable, that is, if the estimation by the tannin-method yields much higher results than that by coagula- tion, it proves that another albuminous substance is present, which is not coagulated by boiling. It is only when the difference is small that the presence of vegetable albumen alone may be in- ferred ; it maythen be estimated by preeipitation by tannin. To render the coagulation-test as reliable as possible, I have recommended chloride of sodium to be added, and the precipitate to be washed, first with boiling water, and subsequently with dilute spirit. I£ the chloride of sodium is omitted the preeipita- tion is generally less complete, and prolonged washing, especially with cold water, is liable to redissolve part of the albumen. Ferments.—Simultaneously with the albumen a number of other substances may be partially or wholly precipitated, which, although agreeing with albumen in many respects, have been too little investigated from a chemical point of view to justify their being classed straightway as albuminoids. I refer to the so-called fer- ments. Like albumen, they contain nitrogen, and are precipitated by strong alcohol, ete. ; most of them, probably, are coagulated like, or together with, albumen when boiled in aqueous solution. They are distinguished from albumen by their fermentative action, which eyinces itself in various ways. Diastase, like saliva, converts starch into sugar, whilst invertin changes saccharose into invert- sugar. Vegetable ferments allied to pepsin (papayotin) peptonize albumen. Myrosin decomposes myronic acid, emulsin amygdalin ; 238 ALBUMINOIDS. but emulsin does not attack myronie acid, nor does invertin convert starch into maltose and dextrin, ete. It is easy, there- fore, to detect diastase in malt, invertin in yeast, emulsin in almonds, ete., the presence of which is anticipated. "The liquefaetion of starch-paste, the conversion of cane-sugar into invert-sugar, the development of hydrocyanie acid and oil of bitter almonds, are changes so striking and so promptly effected, that the qualitative detection of the ferments produeing them leaves nothing to b& desired. But the varied nature of the ferments themselves and of their action renders it exceedingly difieult to detect them in vegetable substances that have not previously been examined, as a general reagent applicable in such a case is yet unknown. It must be admitted that attention has been drawn to the fact that the ferments liberate oxygen from an aqueous solution of peroxide of hydrogen, to which a little tineture of guaiacum has been added, and thus produce a blue colouration of the mixture. But it is hardly to be expected that this property should be shared by all ferments, or that it should be peculiar to them alone. $ 231. Estimation of total Albumen.—The total albumen soluble in water can be estimated by means of acetate of copper, provided that no tannin or other substance precipitated by the same reagent is present in solution. The precipitate produced by an excess of the acetate is filtered off, dried, weighed, and ignited, the resulting oxide of copper being deducted.! If other substances are thrown down with the albumen the nitrogen in the precipitate may be determined, and from that the albumen present calculated. Ritthausen ? and Taraskewiez ? have proved experimentally that the preeipitate contains the whole of the albumen, casein, etc. $ 232. Estimation continued.—Sestini * considers it advisable to precipitate with acetate of lead. In cases in which other nitro- 1 In some instances it is necessary to add a considerable excess for complete precipitation of the albumen. In an experiment made by Taraskewicz with casein, 1 gram of oxide of copper (in the form of acetate) was found to pre- cipitate 4'19 gram of casein; but for complete precipitation an amount of acetate corresponding to 455 grams of oxide had to be added. 2 Loc. cit. 34, etc, ; Ritthausen and Settegast, Archiv f. d. ges. Phys. xvi. 293, 1877. See also Mörner, Upsala Läkarefören. Forhandl. xii. 475, 1877; Fassbender, Ber. d. d. chem. Ges. xiii. 1818, 1880 (Journ. Chem, Soc. zu 205). 3 Noc, Cil. 4 Landwirthsch. Versuchsst. xx. 305, 1878 (Journ. Chem. Soc. xxxiv. 740). s 231. ESTIMATION. 2339 genous substances accompany the albumen in aqueous solution he advises the determination first of the total nitrogen ; a part of the original substance is then to be boiled with er for an hour, made distinetly acid with lactic acid, mixed with acetate of lead, and filtered ; the insoluble residue is dried and the nitrogen in it estimated. He thus assumes that all the nitrogen not present in the form of albuminoids passes into aqueous solution, and the nitrogen in the insoluble residue after preeipitation with lead indicates the total albumen, both soluble and insoluble. In addition to the foregoing precipitants, some of the group reagents for alkaloeids—phosphomolybdic, phosphotungstic acid, potassiomereurie iodide, ete.—also throw down albuminous sub- stances ($ 63). Phosphotungstie acid precipitates peptones, and might therefore be used for their estimation in vegetable infusions previously freed from albuminous substances by coagulation or precipitation with lead.! 1 See Schulze and Barbieri, Landwirthsch. Versuchsst. xxvi. 213, 230, 234, 1881 (Journ. Chem. Soc. xl. 312); Chem. Centralblatt, 714, 731, 747, 761, 1881 ; Defresne, Repert. de Pharm. viii. 453, 1881; Hofmeister, Zeitschr. f. phys. Chem. iv. 253, 1880. From the results recently obtained by Schulze and Barbieri, it appears pro- bable that peptones are of far more frequent occurrence than could have been antieipated. As plants contain peptonizing ferments, the possibility must not be ignored of peptones being produced during the preparation of aqueous infu- sions ; they are also occasionally found ready formed in plants. The following are the more important properties of peptones : They yield with water solutions from which they are precipitated by alcohol, and redissolved by the addition of water. Estimation, however, by precipitation with alcohol is said to yield unsatisfactory results. In aqueous solution they are not coagulated by warm- ing, nor are they thrown down by nitric acid, alum, ferrocyanide of potassium, or acetate of lead, but they are precipitated by tannin ; and in the presence of neutral salts (sulphate of magnesia, etc.) tie separation is often very complete. Peptones are precipitated, as above stated, by phosphotungstie acid, and this takes place in an acetic acid solution ; a property that enables us to separate them from other nitrogenous substances thrown down by the same reagent from solutions containing a mineral acid. The most important reaction of peptones is the so-called biuret reaction. An aqueous solution of a peptone assumes a pure red colour on the addition of caustic soda and very dilute solution of sulphate of copper (avoiding excess) ; Fehling’s solution produces the same effect. The following might temporarily be recommended as a suitable method for the detection of peptones : The (fresh) material to be examined is triturated with sand and water, strained, washed with water and pressed. The liquors are united, acidified with acetic acid, warmed and filtered from the coagulum. From the filtrate any albuminoids remaining in solution are precipitated by the addition of acetate of lead, or, better, by warm- ing with basic acetate and hydrate of lead, and filtered off. The clear liquid is then rendered strongly acid with sulphuric acid, and the peptone precipitated 240 ALBUMINOIDS. Preeipitation by phenol and caleulation from the nitrogen contained in the precipitate has been recommended by Church ! for the estimation of the albuminoids in vegetable infusions, in the presence of amides, etc. My experience in preeipitating albumen, ete., with phenol compels me to doubt the possibility of always obtaining complete separation by this means. Sestini has also expressed himself to the same effect. $ 233. Extraction with Dilute Acid. —It has already been observed that the residue of a vegetable substance, after exhaustion with water, yields albuminous substances to dilute alkalı. The same is the case with dilute acid (2:12 per cent. HC]), the substances extracted being gluten, fibrin ($ 235), gliadin, mucedin, ete. But the albuminoids brought into solution by these two solvents do not appear to be always identical; at least Wagner found that the amount removed by dilute alkali (after exhaustion of the material with water) did not coincide with that extracted by acid. (Compare also $$ 111, 106). It might nevertheless in many cases be desirable to ascertain to what extent the substances allied to albumen resist the action of water, dilute alkali (cf. $226) and dilute acid respectively. In estimating the value of certain vegetable substances as foods, it will often be found desirable to determine what proportion of proteids are dissolved by the combined action of pepsin and hydrochloric acid after the material has been exhausted with water. From experiments that have been made in this direetion it would appear that hydrochlorie acid and pepsin dissolve more than the former alone.” In making such estimations I should recommend 100 cc. of water, 1 gram of 33 per cent, hydrochlorie acid, and 0'1 by phosphotungstic acid. The precipitate is filtered off as rapidly as possible, washed with 5 per cent. sulphuric acid and transferred whilst still moist to a mortar. Itisthen triturated with excess of hydrate of baryta, warmed for a short time and filtered. If the filtrate is colourless, the biuret-test can be applied ; if yellow, it can frequently be decolourized by adding a little acetate of lead, and filtering off from the precipitate thus produced. Animal charcoal should not be used, as it absorbs peptone. Schulze and Barbieri, who pro- posed the foregoing method, have obtained approximate quantitative results colorimetrically. 1 Landwirthsch. Versuchsst. xxvi. 193 (Journ. Chem. Soc. xxxviii. 588). See also Sestini, loc. eit. 2 See Kessler, Versuche über die Wirkung des Pepsins auf einige animal. u. vegetab. Nahrungsmittel. Diss. Dorpat, 1880. 8 234. EXTRACTION WITH SPIRIT. 241 of good pepsin to be taken for every 2 grams of finely powdered substance. Starch, if present in large quantity, might with advantage be previously converted into maltose and dextrin by boiling, cooling to 40°, and digesting for four hours at that temperature, after adding 0°005 gram of active diastase. $ 234. Extrachion with Spürit.—Some of the albuminoids in- soluble in water attract our attention by their solubility in spirit, as, for instance, those known as glutenfibrin, gliadin (or vegetable gelatine), and mucedin. In seeds only have these three substances been detected with certainty ; they remain undissolved when the material containing them is treated with water, or, at most, the mucedin alone is partially taken into solution. They would be removed, however, by the dilute alkali used for the extraction of the glutencasein ($ 226), and it is advisable therefore, in looking for these substances, to treat the material with spirit previously to extracting the glutencasein with alkali. Part, however, of the glutenfibrin and a little gliadin would be left undissolved, and would be subsequently found with the casein ($ 226). The spirit should be used cold, and should be of a strength of about 60 to 80 per cent. The maceration must extend over a considerable period, and the spirit be renewed several times. The united extracts are distilled until the strength of the spirit is reduced to 40 to 50 per cent. (not less). On cooling, a clear slimy mass separates, con- sisting principally of glutenfibrin mixed with a few flocks of gluten- casein and possibly fat (which is, however, better removed by petroleum spirit before treating with alcohol). I£ the majority of the spirit is distilled off from the clear liquor a second precipitate will form, consisting prineipally of gliadin and mucedin, and a further quantity of the same two substances (impure) can be ob- tained by neutralizing the filtrate with a little potash and con- centrating. All these precipitates are triturated with absolute alcohol until they become hard and solid.! Fat, if present, is removed by treatment with ether. We are as yet unacquainted with any method of separating the glutenfibrin, gliadin, or mucedin for quantitative determination. We must therefore content ourselves with making a total estima- ! The spirit dissolves a little glutenfibrin, which can subsequently be precipi- tated by ether. 16 242 ALBUMINOIDS. tion, and applying a few qualitative tests to show the presence of one or more of the substances referred to. $ 235. Properties: Glutenfibrin. — Glutenfibrin is insoluble in water and in absolute alcohol, but dissolves easily in warm 30 to 70 per cent. spirit, separating again on cooling.! It is also taken up by cold 80 to 90 per cent. spirit. Prolonged boiling with water converts it into a gelatinous substance insoluble in spirit, acids, or alkalies. Glutenfibrin dissolves with facility in cold dilute acids (acetie, eitric, tartaric, hydrochloric), and in alkalies ; with ammonia, lime- and baryta- water it gelatinizes. It is pre- cipitated from both acid and alkaline solutions on neutralizing, and is also thrown down by acetate of copper.? Gliadin is characterized by its tough, slimy consisteney. It is sparingly soluble in cold water ; a considerable quantity dissolves on boiling, but, like glutenfibrin, it undergoes simultaneously a partial decomposition. Gliadin is insoluble in absolute alcohol, but dissolves in 60 to 70 per cent. spirit, both cold and warm (especially freely in the latter). In general it resembles glutencasein in its behaviour to dilute alkalies and acids, but ammonia, lime- and baryta- water dissolve it. Boiled with con- centrated hydrochloric acid it yields a bluish-brown solution. It is precipitated by acetate of copper, but not by mercuric chloride. Attention has already been directed ($224) to the high percentage of nitrogen in gliadin. Mucedin is far less tough and elastic than gliadin, and is more easily soluble in 60 to 70 per cent. spirit. It is preeipitated from a cold solution by 90 to 95 per cent. spirit in flocks or friable masses (solutions of gliadin become milky) ; stirred up with water it yields a cloudy mucilaginous liquid, which clears again on standing ; but, if warmed, the aqueous solution becomes cloudy and remains so for a considerable period, till finally a flocky mass separates which is only partially soluble in acetie acid and spirit. 1 On concentrating such solutions the glutenfibrin forms a skin on the sur- _ face of the liquids, which dissolves again on stirring. Gliadin and mucedin do not exhibit this peculiarity. 2 Glutenfibrin agrees with maize-fibrin in most of its properties ; the latter contains only 15°5 (instead of 16'9) per cent. of nitrogen, and is insoluble, or only partially dissolved, by dilute acetic, citric, tartarie and oxalic acids. Zander has recently reported on another albuminous substance soluble in spirit (‘Chemisches über die Samen des Xanthium Strumarium.’ Diss. Dorpat, 1881). 8 236, 237. GLUTEN, ETC. 943 In its other properties it agrees fairly well with gliadin. (Compare also $ 237.) 8 236. Gluten. —Glutencasein, glutenfibrin, gliadin, and mucedin are the principal constituents of the so-called gluten which possesses such importance as a food. An estimation of total gluten is generally made by rubbing down 10 to 20 grams of the meal to a paste with water, transferring to a fine linen eloth, and washing with distilled or rain-water until the washings, on standing, deposit only traces of starch. The mass is then pressed, scraped from the cloth, and dried on watch-glasses, finally at a temperature of 115° to 120°; it should then be powdered and dried again until the weight is constant. In this method of estimating gluten it will be found advantageous to add a weighed quantity (1 to 2 grams) of purified bran, the weight of which is afterwards, of course, to be deducted from that of the total gluten.! According to Benard and Girardin,?the amount of gluten found varies if the mixture is allowed to stand before washing with water. It would be advisable to begin washing about three hours after mixing the meal with water. 8 237. Substances dissolved by Dilute Alkali, not precipitated by Acid and Spirit.—In estimating metarabic acid and albuminous substances sparingly soluble in water, as directed in $$ 103 and 206, it will not unfrequently be observed that the total substances ex- tracted by dilute alkali are considerably in excess of those pre- eipitated by acid and alcohol. A part of the former, therefore, must still remain in solution, and will be recovered, together with acetate of sodium, by evaporating the filtrate ($ 107). We may expect to find here the constituents of gluten (including gliadin) and products of their decomposition. After distilling off the majority of the spirit, they might be precipitated with acetate of copper, and estimated as directed in $ 231. The substances not precipitated by this reagent are probably allied to, or derived from, vegetable mucilage ; they may be estimated by removing the excess of copper with sulphuretted hydrogen, evaporating to dryness and Te deducting the acetate of soda present. With regard to the latter, I may observe Eh it cannot be cal- culated from the amount of soda used, but must be estimated by ! Compare Archiv d. Pharm. cxcv. 47, 1871. ® Journ. de Pharm. et de Chim. [5], iv. 127, 1881. 16—2 244 AMINES. incinerating a portion of the dried residue, and caleulating from the carbonate of soda in the ash. In many analyses made in my laboratory, the amount of soda in solution has been found to be much smaller than was expected from calculation ; part of it was evidently retained in the insoluble residue. $ 238. Other Nitrogenous Substance.. —We possess hardly any knowledge at all of the nitrogenous substances that are not dis- solved by water, alcohol, or alkali. I have already stated ($ 234) that they may sometimes be extracted by hydrochloric acid and pepsin, but Treffner’s researches on the chemical composition of the mosses, alluded to in $ 106, prove that this is not always the case. I will here only remark that, in estimating the nutritive value of a plant, such substances cannot, without further consideration, be considered as albuminoids. AMINES AND THEIR COMPOUNDS. $ 239. Monamines.—According to A. W. Hofmann, monamines may be distinguished from other amines by means of the isonitrile- reaction, as the latter do not evolve the characteristic odour of that compound when warmed with alcoholic potash and chloro- form. Another reaction for monamines consists in warming an aleoholiec solution with bisulphide of carbon, by which a sulphocarbamide of the base is produced. This compound, when heated with an aqueous solution of mercuric chloride (not in excess) develops an odour of oil of mustard.! 8 240. For the separation of ethylamine from diethyl- and triethyl- amine by means of anhydrous ethyloxalate, see A. W. Hofmann 3? the author subsequently availed himself of the method in separ- ating the methyl bases. Carey Lea? recommends picrie acid for the ethyl bases. In Hofmann’s method the ethylamine is converted into diethyl- oxamide, which can be recrystallized from water, and yields ethylamine by distillation with potash. Diethylamine yields under the same conditions oily ethylie di- ethyloxamate, which can be purified by distillation (boils at 260°), and converted by potash into diethylamine. 1 Ber. d. d. chem. Ges. iii. 767, 1870. 2 Journ. f. pract. Chem. Ixxxiii. 191, 1861; Comptes rendus, lv. 749, 1862. 3 Chem, Oentralblatt, 76, 1863. 8 241. ESTIMATION. 245 Triethylamine is not attacked by ethylie oxalate, and can be separated from diethyloxamide and ethylie diethyloxamate by distillation (B.P. 91°). The three corresponding methyl bases behave in an exactly similar manner. Trimethylamine boils at 4° to 5° and can easily be separated from the erystalline methylethyloxamide and the liquid ethylic dimethyloxamate (B.P. 240° to 250°) by distillation. $ 241. Estimation.—Sachsse and Kormann! have published a method for the approximate estimation of amides, based upon their decomposition by nitrous acid with liberation of nitrogen ; the latter gas is collected and measured, and from it the amount of amide originally present is calculated. The apparatus used for the estimation is shown in Figs. 1Oand11. The generating vessel A is of about 50 to 60 ce. capacity, and closed with an indiarubber cork bored with three holes; through these there pass two funnel-tubes, «a and d, and a bent delivery tube c, to which is attached, by means of a long indiarubber tube, 1 Landwirthsch. Versuchsst. xvii. 321 (Journ. Chem. Soc. xxvii. 784); Zeitschr. f. anal. Chem. xiv. 380, 1875. 246 AMINES. a curved glass point d. About 6 cc. of a concentrated aqueous solution of nitrite of potassium (free from carbonate), together with nearly an equal quantity of water, is introduced into the generating vessel. The lower parts of the funnel-tubes, that is up to a little above the tap, say about e, are also filled with water, so as to displace the atmospherie air. Dilute sulphuric acid is now poured into one funnel, and a weighed quantity of the amide dissolved in water into the other, taking care not to allow any bubbles of aür to adhere to the sides. I IN SQ) 11 L = Ni The atmospheric air in the apparatus has now to be displaced, and this is effected by running sulphuric acid, little by little, into the nitrite solution, by which nitrous acid and nitrie oxide are evolved. To ascertain if the displacement is complete, 5 to 10 cc. of the gas from the generating vessel are allowed to pass into the measuring tube (Fig. 11) previously filled with solution of ferrous sulphate. Not more than 0'l cc. should remain unabsorbed. Fresh iron- solution may be introduced, if necessary, from the flask B, as sub- sequently described. The apparatus is now ready for the com- mencement of the actual experiment. 'The measuring-tube, stand- 8 241. ESTIMATION. 247 ing in a pneumatic trough, should be capable of holding 50 to 60 cc., and be graduated to 02 cc. It is filled with the iron-solution contained in B by opening the clip % and blowing through the shorter bent tube in B; by this means the solution can be run into the pneumatie trough ; on opening f and sucking at g the solution rises in the tube until it reaches and passes f, which should then be closed. After replaeing the clip h, the bent point d is introduced under the measuring tube and the solution of the amide allowed to run from the second funnel-tube into the generating vessel, rinsing with a little water, but keeping the tube from e downwards full of liquid. Small quantities of sulphuric acid are allowed to run into the generating vessel from time to time, when the evolution of gas becomes sluggish, taking care that the measuring-tube always contains suffieient strong solution of ferrous sulphate ; this can be ensured by frequently opening the clip } and allowing the solution from B to run into the measuring-tube The end of the decom- position is recognised by the liquid in A assuming a permanent blue colour from excess of nitrous acid. The remainder of the gas is then driven out by filling the entire apparatus with water through the second funnel-tube until it flows into the measuring- tube through d. The delivery-tube is now removed, and the whole of the nitrice oxide absorbed by the introduction of fresh iron-solution. After closing the clip h, the delivery-tube from B is drawn out of the measuring-tube, and the latter transferred to a deep cylinder, where the iron-solution is removed as far as possible and replaced by caustic soda to absorb carbonie acid. When this has been effected, the measuring-tube is lowered in the ceylinder until both liquids have the samelevel. The volume of gas is now read off, reduced to 0° and from it the amount of amide originally present caleulated, deducting 1 cc. as unavoidable error caused by the atmospheric air mixed with the nitrogen ; 28 parts by weight of nitrogen indicate 150 of erystallized asparagine, 131 of leucine, and 181 of tyrosine. ($$ 191, 192). $ 242. Amidie Acids..—The amidic acids referred to in$ 101 are freely soluble in water and 50 per cent. spirit, requiring consider- able quantities of strong alcohol for preeipitation, so that in this respect they resemble such substances as dextrin, levulin, etc. They are precipitated therefore with, or in the place of, dextrin and the like, but differ from these bodies in containing nitrogen, 248 AMIDIC ACIDS. The preeipitate obtained as dextrin (cf. $$ 76, 198, 199) must be tested for nitrogen, and if much is found, experiments must be made to ascertain whether any one of the following substances is present. It may sometimes be approximately estimated, if found, by mixing the aqueous solution with alcohol till it contains about 50 to 60 per cent., filtering, evaporating the filtrate to a syrupy consistence, and now precipitating with 5 to 6 volumes of absolute alcohol. From the amount of nitrogen in the precipitate the quantity of amidie acid present may be calculated. Cathartic Acid occurs in senna, in the bark of Rhamnus frangula, and probably also in rhubarb.! It is a glucoside, yielding by its decomposition sparingly soluble cathartogenic acid and 34:1 per cent. of glucose. According to Kubly, cathartie acid? contains 1:48 to 1'51 per cent. of nitrogen, cathartogenie acid 246 per cent. The latter is easily produced by heating an aqueous solu- tion of cathartie acid with access of air; in fact, that substance decomposes with great facility in the presence of bases and air. In senna and rhubarb it is contained chiefly in combination with bases (the alcohol precipitate containing 4 to 5 per cent. of ash); but in Rhamnus frangula it appears to occur, partly at least, in the free state. It is a strong purgative. Husson? estimates the quality of a rhubarb by ascertaining the amount of iodine an infusion is capable of absorbing ; but Greenish* has shown that this method does not yield reliable results. Sclerotic Acid? is a constituent of ergot, and contains about 4'2 per cent. of nitrogen, but no sulphur ; its activity is not destroyed by acids, ete., if in contact with them for a short period only. In solubility it resembles cathartie acid. Its action, when injeeted subeutaneously into frogs and other animals, is that of a powerful 1 Compare Kubly, “Ueber das wirksame Prineip und einige andere Best. d. Sennesblätter,’ Diss. Dorpat, 1865, and Pharm. Zeitschr. f. Russland, iv. 429, 4655. On Rhamnus frangnla, see also Pharm. Zeitschr. f. Russland, v. 160, 1866. On rhubarb, ibid. vi. 603, 1867 ; xvii. 65, 97,1878 (Pharm. Journ. and Trans. [3], ix. 813, 933, 1879). 2 Probably also sulphur ; cathartic acid from Rhamnus frangula bark con- tains less nitrogen. 3 Union Pharm. 99, 1875 (Year-book Pharm. 344, 1875). * Pharm. Journ. and Trans. [3], ix. 813. 5 Compare Dragendorff and Podwissotzki, Archiv f. exper. Patholog. und Pharm. 153, 1876 ; Sitz-Ber. d. Dorpater Naturf. Ges. 109, 392, 1877 (Pharm. Journ. and Trans. [3], vi. 1001). 8 243. STARCH, LICHENIN, ETC. 249 poison.! It is preeipitated by tannin and basie acetate of lead, and from concentrated solutions also by chlorine-water and phenol. It does not share with albuminoids the reactions men- tioned in $ 92. On keeping ergot for any length of time, part of the selerotic acid appears to be converted into an allied substance containing 6°6 per cent. of nitrogen, which has been named scleromuein. It can be extracted with warm water, but requires less alcohol for pre- cipitation than sclerotic acid. Diffused in water whilst still moist, it forms a mucilaginous liquid ; but once dried, itis not dissolved by cold water, and not with facility by warm. It resembles sclerotie acid in its action and other properties. STARCH, LICHENIN, WOOD-GUM, ETC. 8 243. Starch.—Starch is not, as is well known, a homogeneous substance, but it is nevertheless usual, and very properly so, to estimate the whole of the carbohydrates of which it is composed as directed in S 113 to 115. Formerly three principal con- stituents of starch were generally distinguished : first, one striking a blue colour with iodine, and passing into solution when starch is triturated with powdered glass and water—soluble starch, amidulin, e amylon (Bechamp) ; secondly, a substance character- ized by its insolubility in cold water, solubility in saliva, etc., aud by the blue colouration it yields with iodine, granulose, the prin- cipal constituent of all starch ; and thirdly, cellulose, which, in the form of a membrane, gives to the starch grain its particular shape, is coloured yellow by iodine (after boiling with water, violet), and is converted by chloride of zine into a substance that is tinged blue by the same reagent. Some years ago Nägeli? stated that in his opinion there ex- isted two different modifications of amylon, which he called blue ! From 0:03 to 0'04 gram produces in frogs a swelling of theskin and almost complete paralysis, commencing at the hinder extremities. Irritants produce no effect, and indeed the animal gives no other sign of life than an occasional feeble contraction of the heart. Although its condition may appear to improve in the course of five to seven days, it sometimes succumbs to a relapse. ” Annal. d. Chem. und Pharm. elxxiüi. 218, 1874 (Journ. Chem. Soc. xxviii, 55. See also Musculus, Annal. de chim. et de Phys. ii. 385, 1874 (Pharm. Journ. and Trans. [3], v. 3); Musculus and Gruber, Journ. de Pharm. et de Chim. xxviii. 308, 1878 (Journ. Chem. Soc. xxxiv. 778); Bondonneau, Repert. de Pharm. iii. 231, 1875 (Journ. Chem. Soc, xxix. 365) ; Journ. de Pharm, et de Chim. xxiii. 34, 1874; Bechamp, ibid. 141. 250 STARCH, LICHENIN, ETC. and yellow, according to the colour they yielded with iodine. These two were connected by intermediate modifications striking violet, reddish and reddish yellow eolours with iodine, differences which are probably referable to variations in the density. In accord- ance with this theory the several modifications vary in the resistance they offer to solvents and chemical agents. As the blue modification is the most easily attacked, it might be considered to be that of lowest density. It is followed by the violet, red, ete., in succes- sion up to the yellow, the densest form of which shows a great resemblance to cellulose. When starch is boiled the blue modifi- cation passes into solution, carrying with it a little of the yellow. If the former is removed by allowing it to decompose, the yellow modification separates out. From a solution of the latter, pre- pared by prolonged boiling with water and concentrating, erystals of amylo-dextrin can be obtained, which are coloured yellow by iodine. The bodies above referred to occur in different proportions in the different varieties of starch, and the amount of either present might possibly be found to be characteristic of the starch under ex- amination. It might, for instance, be ascertained by comparative experiments how long the action of an acid of certain strength must be continued before the blue or red colouration with iodine ceases to be produced. For the isolation of the yellow modification, formerly called cellulose, y amylon (B&champ), I have recommended digestion at a temperature not exceeding 60°, with 40 parts of a saturated solution of chloride of sodium containing 1 per cent. of hydrochlorie acid, and washing with water and dilute spirit. I have thus obtained 3°4 per cent. from arrowroot, 2'3 per cent. from wheat-starch, and 5°7 per cent. from potato-starch. $ 244. Hydrocellulose—A. blue colouration of the cell-wall is fre- quentlynoticed when sections of vegetable substances are moistened with iodine water. It was probably this reaction that gave rise to the theory that a modification of cellulose could occur striking & blue colour with iodine. I do not concur in this view ; in fact, I am convinced that in such cases the cell-wall in question contains besides cellulose, which is characterized by its power of resisting the action of chlorate of potash and nitric acid, other carbohydrates (amyloid), probably, at least ın part, of the composition C,H ,50,,, agreeing therefore in this respect with arabie acid, pararabin, etc. Whether these & 244, 245. LICHEN-STARCH, LICHENIN. 251 carbohydrates are hydrocelluloses, such as are formed from cellulose by the action of concentrated sulphuric acid or chloride of zine, is a matter for further inquiry. If the treatment with the above oxidizing mixture of chlorate of potash and nitrie acid ($ 119) is continued long enough, such substances are always destroyed. Some of them are soluble in boiling water. This is the case with one contained in the asci of certain lichens (Cetraria), etc., from which it is extracted, together with lichenin, by boiling with water ; hence the erroneous idea that the lichenin itself was coloured blue by iodine.! Berg’s researches have shown that if a decoction of the lichenin be allowed to gelatinize by cooling, cut into pieces and macerated in distilled water, the whole of the substance that strikes a blue colour with iodine passes into solution, from which it can be isolated by precipitation with alcohol, although impure and not free from ash. After drying it is to a great extent in- soluble in water, and is converted into sugar by boiling with dilute hydrochloric acid (4 per cent. of acid of sp. gr. 1'12) for a period of two hours, a change which is not effeeted by pure water. The glucose produced is dextro-rotatory, and as the decomposition takes place tolerably smoothly, the amount of the substance, which we may temporarily call lichen-starch, can be determined by estimating the sugar thus formed. Lichen-starch dissolves tolerably easily in ammonia of sp. gr. 0°96, and is precipitated from this solution by spirit. It appears to be more difficultly soluble in dilute alkalies, and is not converted into sugar by diastase or saliva. $ 245. Lichenin.—Lichenin is characterized by its property of gelatinizing, which is exhibited by a solution containing 1 in 60. It is insoluble in cold water, alcohol, and ether ; boiling water dissolves it, as do also ammonio-sulphate of copper and concen- trated (20 to 30 per cent.) potash. From its solution in strong potash it can be precipitated by alcohol in the form of a potas- sium-compound containing up to 10 per cent. of alkali. Concen- trated hydrochlorie acid also dissolves it, but with simultaneous (partial) decomposition. When boiled with dilute acid it is converted with even more facility than lichen-starch into a dextro- ! Compare Berg, ‘Zur Kenntniss des in Cetraria islandica vork. Lichenins und iodbläuenden Stoffes,’ Diss. Dorpat, 1872. From Berg’s experiments it would appear that the formula C,H,,O, would indicate the composition of lichen-starch better than C,,H,,0,, ; the same is true of lichenin, 252 CELLULOSE, LIGNIN, ETO. rotatory jermentable sugar, so that this method may be adopted for its estimation. Ammonia dissolves it with difficulty, and it undergoes but little change when heated with potash in sealed tubes ($ 115). Gelose,! the gelatinizing constituent of many alge, agrees with lichenin in most of its properties, but is insoluble in ammonio- sulphate of copper, and is less easily converted into sugar. By decomposition with dilute acids, arabinose (lactose) is produced in place of the glucose yielded by lichenin. The gelose appears to be accompanied, at least in Spherococeus lichenoides, by a carbo- hydrate? soluble in dilute hydrochloric acid, but differing from pararabin ($ 112) in yielding glucose when boiled with an acid. s 246. Wood-gum.—Thomsen? found that when ligneous tissue, previously exhausted with water, spirit, and very dilute alkali, was macerated with caustic soda of sp. gr. 1'1, a substance was ex- tracted, the composition of which he ascertained to be C,H O5, and which he named wood-gum. It can be isolated from its solution in soda by acidifying and adding alcohol. When once dried, cold water will not redissolve it; this is, however, effected by boiling. It is preeipitated by basic acetate of lead, is converted into glucose by boiling with a dilute acid, and is not coloured blue by iodine. An alkaline solution is levo-rotatory. It differs from lichenin in not possessing the power of gelatinizing, from metarabin in not being dissolved (when dry) by 0'l per cent solution of soda. A similar substance was obtained by Pfeil? from parenchymatous tissue (agreeing, however, in composition better with the formula C,,H,50,,, & hydrocellulose), by Treffner from mosses, and by Greenish from alge. CELLULOSES, LIGNIN, AND ALLIED SUBSTANCES. 8 247. Celluloses, etc. —Fremy and Terreil® assume that woody tissue is chiefly composed of three different substances, which they distinguish as cellulose, incrusting substance, and cuticular sub- 1 Compare Morin and Porumbaru, Comptes rendus, xc. 924, 1081, 1830 (Year-book Pharm. 120, 121, 1881). | 2 Greenish, Archiv d. Pharm. [3], xx. 241. 3 Journ. f. pract. Chem. [2], xix. 146, 1879 (Year-book Pharm. 99, 1880). 4 Loc. ch, . 5 Journ. de Pharm. et de Chim. vii. 241, 1868. 8 247. COMPOSITION OF WOODY TISSUE. 253 stance. The first is said to be the only one capable of resisting the action of chlorine-water ; it can be isolated by the method detailed in $116. The authors overlook the fact that several units per cent. of a substance probably isomeric with cellulose (? intercellular substance), removable by chlorate of potash and nitrie acid, are left associated with the cellulose. The cuticular substance alone is said to be insoluble in a mixture of 1 eg. of sulphuric acid with 4 eg. of water ; it can be isolated by treatment with acid of that strength, followed by washing with pure water and dilute alkalı. The incrusting substances are estimated by difference. In a more recent publication, the authors observe that the following are the prineipal substances they would expect to find in tissue previously exhausted with indifferent solvents : Cellulose, soluble in ammonio-sulphate of copper. Paracellulose, insoluble in the same until after it has been acted upon by acids. Metacellulose (£ungin) insoluble in ammonio-sulphate of copper. All three modifications of cellulose are soluble in H,SO,, 2H,O. (Compare also $ 248). Vasculose, insoluble in H,SO,, 2H,O, and in ammonio-sulphate of copper ; soluble in alkalies only under increased pressure, and decomposed by treatment with chlorine-water, followed by wash- ing with dilute alkalies. Cutose, insoluble in H,SO,, 2H,O, and in ammonio-sulphate of copper, but soluble in alkalies under the ordinary pressure. Pectose, convertible by acids into soluble pectin.! I would observe that the substance designated as vasculose (formerly called incrusting substance), agrees in the main with my lignin ($ 116). Lignin cannot, unfortunately, be separated from cellulose without decomposition, and it is therefore impos- sible to adduce direct proof that it does not consist of a mixture of several chemical individuals. Nevertheless, I think it probable that in some 'instances the cellulose is accompanied by a single definite substance, “lignin.’ Stackmann? exhausted vegetable substances rich in lignin with the indifferent solvents already alluded to, as well as with dilute soda and dilute acid, and then determined the approximate composition of the lignin by making 1 Comptes rendus, Ixxxiii. 1136. (Journ. Chem. Soc. xxxi. 229). 2 ‘ Studien über die Zusammensetzung d. Holzes.’ Diss. Dorpat, 1878. 254 CELLULOSE, LIGNIN, ETC. an ultimate analysis of the material that had been thus treated, bothbefore and after the action of chlorine-water. Several varieties of wood yielded tolerably concordant results. The lignin of dicotyledons appeared to contain between 53'1 and 59'6 per cent. of carbon, 4°4 and 6°3 per cent. of hydrogen, 34'1 and 389 per cent. of oxygen ; the majority of his results agree very well with Fr. Schulze’s! (Ö=55°5, H=5'8, O=38°6) ; but German walnut and mahogany show a little variation, probably due to the larger amount of foreign substances they contain. All the dieotyledonous woods examined by Schulze and Stackmann must have contained at least one substance in notable quantity, viz. wood-gum, which was not discovered until after the publication of Stackmann’s work. Experiments made by Schuppe,? at my suggestion, showed that poplar wood contained 3'25 per cent. of wood-gum, mahogany 3:37, American walnut 456, German walnut, 6'32, oak 6°03, and alder 7:09. Deducting the wood-gum present, the average amount of lignin in the majority of woods is about 17 per cent. (mahogany 20°4), and its mean composition, 60°56 per cent. C, 4:66 per cent. H, and 34°80 per cent. O. In this respect it ap- proaches catechin, many tannins and phlobaphenes, and agrees fairly well with the lignin of coniferous woods which contain no wood-gum. Stackmann found about the same quantity of lignin in the wood of gymnosperms as Schuppe did in that of angio- sperms, viz. 16 to 17 per cent. Koroll? found the lignin of sclerenchymatous tissue (hazel-nut, walnut) to contain from 51°5 to 54'2 per cent. of carbon, 48 to 5°5 per cent. of hydrogen, and 40:1 to 447 of oxygen, and esti- mated its quantity at 14'3 to 157 per cent. A substance re- sembling wood-gum also oceurs in the sclerenchymatous tissue of nut-shells. Bast-fibres (lime and elm) yielded him 145 to 15°8 per cent. of lignin, containing 53°6 to 54'9 per cent. of carbon, 4'9 to 6'0 per cent. of hydrogen, and 40'1 to 40°4 per cent. of oxygen. On the other hand, from the outer birch-bark (rich in euticular substance,) chlorine-water extracted 11 per cent. of a substance of an entirely different composition; vi. C=727, H=7'8, O=194. (Of. $ 250.) 1‘ Beitr. z. Kenntniss d. Lignins.’ Rostock, 1856. 2 Beiträge z. Chemie d. Holzgewebes. Diss. Dorpat, 1882. 3 < Quant. chem, Unters. über d. Zusammensetz. d, Kork-, Bast-, Scleren- chym. und Markgewebes.’ Diss. Dorpat, 1880. 8 247. SUBERIN. 255 The tissue of turnip, chicory-root, and elder-pith, which is prineipally parenchymatous, yielded hardly anything to chlorine- water. Pfeil also came to a similar conclusion with regard to the tissue of apples.! The substance formerly known as suberin is in part the cuti- cular substance just alluded to; it should, however, be observed that under this name less recent authors understood a mixture of fat, wax, tannin, ete.”? Siewert has published a minute in- vestigation of the substances that accompany suberin, but not of the suberin itself ; our knowledge of that substance is but very insufficient, and I can only state that it is not dissolved by the usual solvents, that it is more easily attacked by certain oxidizing agents than lignin, but is more diffieult to remove cempletely by digestion with chlorine-water. Nitrie acid of sp. gr. 1'3 attacks it very energetically; and with an acid of sp. gr. 1'4 the action may be so violent as to cause ignition. It resists chromice acid more powerfully than lignin. Whether suberin really yields the ceric and suberic acids that have been obtained by the decom- position of cork is still a matter of uncertainty. Siewert estimates the amount of suberin in cork at 90 per cent. ; but I think this is too high. I feel convinced that the residue he speaks of as suberin must have contained a consider- able quantity of true cellulose. (Koroll found 50 per cent. in the outermost parts of birch-bark.) In my opinion, the hardening substance of many woody fungi is possibly identical with suberin.? For the microchemical characters of cutin, lignin, ete., see also Vogl* and Poulsen.®° (See also $ 249.) The remarkably constant proportion existing between the amount of cellulose and lignin, ete., present in varieties of wood, raises the question whether these two substances do not occur in combination with one another. The attempt has frequently been made to regard the substance of the cell-walls of lignified tissue 1 Loe. cit. ? Compare Siewert, Zeitschr. f. d. ges. Naturw., xxx. 129; Journ. f. pract. Chem. civ. 118,1868. See also Höhnel, Sitz.-ber der phys. math. K. d. Akad. d. W.in Wien, 1877 ; Bot. Ztg. 783. ® Compare my ‘Chem. Unters. eines an Betula alba vork. Pilzes.’ Diss. Petersburg, 1864. 4 Zeitsch. d. österr. Apotheker-Ver. 1867, 16, 34, 60. 5 ‘ Botanisk Mikrokemi.’ Kjöbenhavn, 1880. 256 CELLULOSE, LIGNIN, ETC. as a special chemical compound (gluco-lignose, gluco-drupose of Erdmann). Erdmann assumes that it is decomposed by hydro- chlorie acid with production of glucose, together with lignose or drupose, and that with nitrie acid it yields cellulose, whilst the lignose or drupose undergoes further decomposition. Bente,! who doubts the existence of gluco-drupose, shows that wood-cells (? lignin) yield pyrocatechin when fused with potash. $ 248. Oellulose.—The cellulose obtained from various plants in the manner indicated does not appear to be invariably of the composition O,H,,0O,. That isolated by Stackmann from coni- ferous wood was represented by the formula 5(C,H.,O;) + H,O, and the cellulose that certain sclerenchymatous and bast-tissues yielded to Koroll was of similar composition. "The latter chemist also prepared it from parenchymatous tissues, and then it generally possessed a composition approximately indicated by the formula 5(C,H,.0;)+2H,0, whereas the wood of most dicotyledons contains, according to Stackmann, a cellulose of the formula 5(C,H,00;)+3H;0. Im these experiments the substance was exhausted with water, alcohol, dilute soda, dilute acid, a mixture of one part of sulphuric acid with four of water, and chlorine- water, previously to being treated with nitrie acid and chlorate of potassium. Schuppe has shown that the action of the sulphuric acid, the use of which I recommend to be diseontinued, results in the formation of a hydro-cellulose If the treatment with sulphuric acid was omitted, the cellulose obtained from woods corresponded in composition to the formula C,H,,O;. But the cellulose isolated from apples by a process that did not in- clude treatment with sulphurie acid showed a deviation in com- position from the formula C,H.,0;.? The cellulose of fungi (cf. $ 249) frequently shows a com- position corresponding almost exactly to the formula C,H, ,O;. . $ 249. Varieties of Cellulose. —The variations observed in celluloses isolated from different plants is partly to be ascribed to the above- mentioned difference in composition, and partly probably to varia- tions in density. For instance, the cellulose of most phanerogams 1 Annal. d. Chem. und Pharm. exxxvii. 1, 1866, and Jahresk. f. Pharm. 9, 1867. Compare also Bente, Ber. d. d. chem. Ges. xiii. 476, 1875; Journ. f, Landwirthsch. 166, 1876. Compare also Bevan and Cross on the chemistry of Bastfibre, Chem. News, xlii. 77, 91, 1880, 2 Compare the dissertations of Pfeil and Treffner already quoted. 250. CRUDE FIBRE. 257 is dissolved by ammonio-sulphate of copper,! and repreeipitated in an amorphous condition by dilute acids ; but that of many fungi is either insoluble or taken up to a slight extent only, and then with great diffieulty. Concentrated sulphuric acid and syrupy solution of chloride of zine render cellulose capable of assuming a blue colour with iodine >? but in some instances the reaction is found to fail,? and Schulze’s reagent for cellulose, which is not without its value as a micro-chemical reagent, cannot therefore in such cases be employed for colouring the cell-wall. The facility, too, with which cellulose can be converted into glucose varies. Masing observes that fungus-cellulose undergoes the change more easily than flax-fibre. * $ 250. Orude Fibre. —From what has been said of the isolation of cellulose, it follows that the erude fibre of the physiologist and agrieultural chemist cannot be exactly identical with that sub- stance. To estimate the crude fibre, the material is generally boiled for half an hour, first with 1 per cent. sulphuric acid, and then with 1 per cent. caustic potash. The residue is exhausted with cold water, alcohol, and ether in succession, dried and weighed. In this crude fibre we may antieipate the presence of a little undecomposed wood-gum, lignin, and suberin, as well as part of the hydrocelluloses mentioned in $$ 117, 244. An apparatus that may be used with advantage in this deter- mination has been described by Holdefleiss.? 1] prepare this reagent by precipitating hydrate of copper from a solution of the sulphate by dilute caustic soda, rapidly filtering off, pressing and dissolving in the requisite quantity of 20 per cent. solution of ammonia. 2 The reagent known as Schulze’s can be prepared by dissolving 25 parts of dry chloride of zinc and 8 of iodide of potassium in 83 of water, and adding as much iodine as the solution will take up when warmed for a short time with it. 3 On cellulose of fungi, see Masing, Pharm. Zeitschr, f. Russland, ix. 385, 1870. Richter (Chem. Centralblatt, 483, 1881) has recently denied the existence of & special fungus-cellulose as the prolonged action of caustic alkalies converts it into ordinary cellulose. But is it not probable that such treatment actually produces a chemical change ? *On cellulose see Payen, Annal. d. Sciences naturelles, xi. 21, xiv. 88; Fromberg, Annal. d. Chem. und Pharm. lii. 113; Heldt and Rochleder, ibid, xlviii. 8; Schlossberger and Döpping, ibid. lii. 106 ; Schlossberger, ibid. cvii. 24, 1858 ; Peligot, Comptes rendus, Ixiii. 209, 1861; Knop and Schneder- mann, Journ. f, prakt. Chem, xxxix. 363, xl. 389 ; Henneberg, Annal. d. Chem. und Pharm. cxlvi. 130, 1869; König, Zeitschr. f. anal. Chem. xiii, 242, 1879. ° Compare Holdefleiss, Zeitschr. f, Anal. Chem. xvi. 498, 1877, and Landwirthsch. Jahrb. Supp. vi. 101, IT 258 PERCENTAGE COMPOSITION OF THE CONSTITUENTS OF PLANTS MENTIONED IN THE FOREGOING WORK. NAME. FORMULA. & | je OÖ. N: S Abietic acid . C,Hs0; 78:51 \ 93902 | 1191 Absinthiin C.H;305 7038 | 8'50 | 2112 Acetic acid „H,O, 40:00 | 6'66 | 5333 Achilleine C.H33N5075 | 4384 | 6°96 | 4384 | 5:12 Aconitine 0,HuNO, | 01:89) 6:07 | 2977| 237 Aconitie acid . A605 41'38 | 345 | 5517 Adansonin . C,H,0;3; | 48'30 | 5°95 | 4575 Aesculin gıH24013 | 5207 | 496 | 42°97 Albumin ? 52°45-| 6°81-| 22°21-| 15°65-| 0°8 53-97 | 777 | 28°50 | 15°92 Alizarin C,4H30; 75:00 | 83:57 | 2144 Alkannin C,H.0, |6972 | 5-42 | 24-86 Amanitine C,H,,NO 57:69 | 13°46 | 15°38 | 13°46 Amygdalin C.,H5sNO,, | 5251 | 5°91 | 38:52 | 3°06 Amyrin oo 83:49 11179 | 473 Anacardie acid CuH0, (?) | 75:04 | 9:07 | 1589 Anemonin 1H120, (2) | 62:50 | 417 | 3333 Anethol „Hn0 8108 | 811 | 10:81 Angelic acid . C,H3;0; 60:00 | 8:00 | 32:00 Antiarin C,4H2005 62:68 | 746 | 29°85 Apiin Hg0, |52°9 | 52 |419 Arabic acid 12H99011 42:10 | 643 | 5147 Arachic acid . 20H400> 76'92 | 12:82 | 10°26 Arbutin C,,H34014 537 61 | 40'2 Aribine 9, HooN4 78:43 | 5°68| ... |15'89 Aricine O,H,N,0, | 70.05 | 8°59 | 1625 | 71 Asclepin 90H 3403 7454 | 10°56 | 14°90 Asparagin 4HsN,0, | 36'386 | 6°06 | 36°37 | 2121 Aspidospermine C„H,N,0, |74°57 | 848| 9004| 791 Athamantin . C,,H307 66°98 | 6'98 | 2604 Atherospermine O4 Nn05; 17087 | 787 11098) 51 Atropine C,E,NO, 17058 | 795 | 1660] 288 Barbaloin C,,H,.0, (9) | 6071 | 595 | 33:34 Bassorin C,H0H 42:10 | 6°43 | 51'47 Beberine „HNO, | 7381| 675 | 1544 | 4°50 Benzaldehyde C,H,O 1924 | 565 | 1511 Benzoic acid . C,H;03 6885 | 492 | 26°23 Benzoheliein . C,,Hg053 61°86 | 5°15 | 32°99 Berberine CuH,NO, 71:64 | 5:08 | 191071. #18 Betaine . C,H,,NO, |44'44 | 9:63 | 35°55 | 10'37 Betaorein C;H1005 69:56 | 724 | 2320 Betulin . CyHg05 | 82:57 | 11'386 | 606 Bixine C,H 340; 74:66 | 7°55 | 1778 Boheic acid C,H,00g 4421 | 526 | 50°53 Borneol C,H10 77'92 | 11°69 | 10°39 Brasillin C,H40, |erıı | 548 | 27-46 Brucine C,H56N50, | 7000 | 6'64 |16'26 | 7'10 Bryonin C,Hs0019 .| 60°00 | 8°33 | 31°66 Bryoidin C,H3s0; 73'62 | 11°66 | 1472 PERCENTAGE COMPOSITION OF CONSTITUENTS. 259 NAME. FORMULA. C. H. 0. N. S. Butyl alcohol , © } C,H,0 64°80 | 13°51 | 21°62 Butyric acid . ; } C,H;0, 54:55 | 9:09 | 3636 Caffeine s .| C;H,0N,05: |49'48 | 5°15 | 16°5i | 28°86 Caffeo-tannic acid . -| C44H1607 5675 | 541 | 3784 Cailcedrin . ’ . ? 64°9 71:6 |27°5 Cainein b : - ? 5824 | 7'38 | 34°38 Callutannic acid . .| 04H40,(2) [5153 | 430 | 4417 Camphor ; ? i CuH10 78'94 | 10'53 | 10°53 Cane-sugar . ; | CHaOı 42:10 | 643 | 5147 Caoutchouc „ ; R CHıs 88:24 |11'76 Capaloin j ; | CyeHa00; (2) |59°26 | 617 | 34:57 Capric acid . ; | CyoH002 6976 | 1162 | 18°61 Capric aldehyde . : C,Hn0 7692 |12'82 | 10°26 Caproic acid . : - C,H,03 62:07 |10°35 | 2758 Capryl alcohol ; - C;H,,0 73'84 |13'84 | 1232 Caprylic acid . : x C;H,503 66°67 |11'11 | 22°22 Capsaicin . . ; C,H,,0, 70:00 | 929 | 20°71 Carl »- » 2.) 04H40, (2) | 80:25 | 9-55 | 10-20 Carotin ; i C,,H;,0 84:37 | 937 | 626 Carthamin s | O4H180r 5675 | 5°40 | 3785 Carvol . ö : i CoH10 8000 | 9:33 | 1077 Caryophyllin . ; $ CH1s0 78°94 |10°53 | 10:53 Catechin ’ | CH1s05 60:96 | 4°81 | 3423 Catechu-tannic acid C,H3,015 6246 | 4°66 | 32:88 Cathartomannite + C;H1405 39:56 | 769 | 52°75 Cathartic acid ö i ? 5757 | 512 |34°96 | 1:50 | 085 Cellulose : PS C;H,005 44-44 | 6'17 | 49:39 Cericacid . : 5 ? 64:23 | 877 | 27:00 Cerotic acid . ; .ı (6,40, 19:02) 13.17 | 781 Cerotyl alcohol . ; C,,H,;0 81:81 | 1414 | 405 Cetraric acid . Be C,,H1603 60:00 | 444 | 35:56 Cetyl alcohol . f R CH;40 18:68 |13°95 | 737 Chelidonine . . | CyH,7N;30; |68:06 | 5°08 | 1432 | 1254 Chelidonie acid . 5 C,H,O, 45°65 | 2:17 | 5224 Chlorogenine , .‚Cy HNO, H3,0| 65:97 | 5°75 |20°95 | 7°33 Chlorophyllan (1° 37 Ba , ? 184 | 97 | 957 562 Cholesterin , s C,H,0 84:11 |12:15 | 374 Cholin . ‚ £ .) C;H,NO, [49:59 |12°39 | 26°44 | 11°57 Chrysarobin . . R C,,H5507 1231 | 522 | 2247 Chrysorhamnin . CEO 58:23 | 464 13713 Chrysophanic acid . | O,4,004 70:87 | 3'94 | 25°19 Chrysopierin . ; C,H,40, (2) 17081 | 4'835 | 2484 Cinchonine, Cinchonidine C;H»NO 17755 | 748 | 544 | 9-53 Cinchona-red . ; | 05440, (2) |53°33 | 5°19 | 4148 Cinchona-tannie acid CzH03 (2) |44°84 | 5'383 | 49-83 Cinchona-nova red. ; C,H)0; 91:07 | 5.15 83:64 Cinchona-novatannicacid C3H,017 92:01 | 5:88 | A9°TT Cinnamein . : i C,H,40, 8067 | 5'88 |13°45 Cinnamic acid e : C,H,0, 722.970, 0241. 2162 Cinnamic aldehyde i C,H,0 8181 | 6:06 | 1213 Citric acid . ; 1 C,H;0, 8/50. | 4:17 158°33 Cniein , 5 ; | C5H,015 (2) | 63-00 | 7°00 | 30-00 Cocaine ; . | CH NO, |66°44 | 6:57 12215 | 4:84 Odene . . | CjHsNO, [72:24 | 7:02 |16:06 | 4-68 Colchiceine , . | CyHuNO, 16344 | 6:58 |25°20 | 4-38 Colchieine , v | O,H2,NO, 160°53 | 682 |28°50 | 4-15 Coloeynthin . k | CH0, (2) 15978 | 7°47 | 3275 Columbin , : | CyH5»0, 6528 | 5°69 | 29-03 260 PERCENTAGE NAME. Conessine (Wrightine) Conglutin Conhydrine Coniferin Coniine . Convallamarin Convallarin Convolvulin . Coriamyrtin . Cotoin . Crocin : Crotonie acid. Cubebin Cumarin Curacao-aloin Curarine Curcumin Cusconine Cyclamin Cyclopin Oytisine Daphnin Datiscin Delphinine Delphinoidine Dextrin , r Digitalin Digitonin Digitoxin » Ditaine . Dulcamarin Dulecite . Elaterin Ellago-tannie acid Ellagie acid Emodin, Emulsin Ericolin Erythrite Erythrocentaurin Ethyl alcohol, Eugenin Eugenol Euphorbon Evernic acid . Everninie acid Ferulic acid Filiein . s Frangulic acid Fraxin Fruit-sugar Fumaric acid. Galactose Galitannie acid Gallie acid Gardenin Gelsemine Gentisin R COMPOSITION OF CONSTITUENTS. FORMULA. AAN Des. a8 4 225 DEN en MH RE : AD t9 oO =. Luiz td Hi ©0000 3 oe 5 SO m w io EFFE 1 =? 90H 550; 14 10010 UZE0B O1sH1005 C;;H,605, „Ho 4 27248 C,H,0 C,,H}503, 1 Dt A C;H,,0 C,,H,0;, 9104 C.H0, 26-3079 C,H150; Q;, 6235 be-2-6 C,H,O, C,H,505 C,H;0, (?) C,H,0, C,,H150; CH7NO, 14-105 C. 78'3 5024 6712 56'14 76:81 53:91 6316 54:87 6386 6984 6233 55.61 6742 7397 5822 81°51 6741 7005 5529 44:44 73'85 5239 5408 6455 709 44:44 59:95 5321 63:60 68°39 5764 3956 6896 49:69 5563 6667 4878 51°00 39:34 6807 52°17 GB, 73°17 8182 6144 5934 61'23 6420 676 5102 40°00 41'838 4000 4884 4949 60'85 6700 65 11 H, 11°2 6°81 fat NOHWEONNANTOSTODSOMPBDOMNTNTWIMNDHM N NANSHOSSAKTHSHSHRAATSUTONADKHRAGSHE STEH SNDOHRAWORHOHDOOD Doors oDmyNTOOVOUST 700 D VorRVvmRowWwoaRHM SANS RASDON AERO Ö. ? 2413 11°19 3743 3750 2724 3776 2976 2539 3117 3720 2696 2192 3628 26°96 1625 3687 51°80 492 4283 4120 2347 15°6 49:39 32:00 39:19 2790 16:58 3494 5275 23:00 4725 4238 3063 24°67 4200 5246 2689 3479 19:51 19°51 714 3374 35°'17 3265 29:63 38'2 4489 5333 55°17 53:33 4651 46'86 3440 1630 31'02 N. S. 0) 18:37 | 0.45 9-79 11'20 5:28 741 IB IR 7:10 PERCENTAGE COMPOSITION OF CONSTITUENTS. 261 NAME. FORMULA. C. BR 9: N, 8, Gliadin . Aa - ? 52:60 | 7°00 12149 | 18°06 | 085 Globularin . x ! C,H4014 DTEB2 E70 55507 Glutencasein , j : ? 51:0 167 1254 10%: | 08 Glycerin , - ’ C,H30, 39:13 870 52°17 Glycolie acid . A ; C,H,O, 3l’58 | 5°26 | 63-16 Glyeyrrhizie acid . ı Cu NO,s 15912 | 705 182:06&| 117 Grape-sugar . ; F C;H,0; 40:00 | 6°66 | 5334 Gratiolin - = E C,H3407 6217 | 881 | 29:02 Grönhartin . > . CHH0:(?) |74°6 all Gyrophoric acid . } C.Hz015 60:81 | 490 | 34:29 Hzmatoxylin j CsHnu0% 63:57 | 463 | 3179 Harmline . . .| 03H4N.0 [72:90 | 6:54 | 7:48 | 13-08 Harmine C,H N,0 1358| 5°67 | 754 | 13°21 Hedericacid. . .| C4Hs04 |66'68 | 9-63 | 23-71 Helenin.. ; : f C„H30; 16'83 | 8:53 | 14°64 Helleborein . e | CO Au0ı 15235 | 738 | 4027 Helleborin . . u 023.0; 1578 | 1°37 |16°85 Heptyl-alcohol . ; C,H,,0 1241 | 1379 | 13:79 Hesperidin . ä | O9Has0ıa 5477 | 5'39 | 39:84 Hydrocarotin . . . C,H,0 8244 | 1141| 6°15 Hydrocyanic acid . . CNH 44-44 | 3°70 | 51'85 Hydroquinone : ; C,H,;0; 65°45 | 516 | 29:09 Hyoscne . . .| CyH,N0, |70:58 | 7-95 |16-16 | 4-84 Hyoscyamine.. | OyrHz,NO,;, 17058 | 7:95 |16°16 | 4'84 Indien. . . [05 H5N50,,(2)\49'60 | 4-92 |43-26. | 2-22 Indigo-blue . s > C;H,NO 13:28 | 3:82 | 12-22 | 1068 Insite . | &Hn0s |40°00 | 6-66 | 53-34 Inulin ’ . ‚ C;H,005 4444 | 6'17 | 49:39 Ipecacuanha tannic acid. C,,H,s0, (2) |56'37 | 6'04 | 37:59 Isoduleite . f ; C;H140; 39:56 | 769 | 52:75 Jalapin . s . :| CyH,0,6 15666 | 777 |85°57 Jervine . ; . .| CyH;N:0,;, |61'03 | 8°56 | 25°27-| 5°14 Kämpferid . : 2 ? 6448 | 440 | 31°20 Kinic acid . . . C,H20; 4375 | 6'30 | 50:19 Ron . 2.0. 044200 [6526 | 6:66 | 28-07 Lactic acid . . ; C,H,O; 40°00 | 6°66 | 53:34 Lactucerin . . ‘ C„Hs0, 81'81 |11°04 | 714 Laserpitin j i 0,40, 66°05 | 8:26 | 2569 Laurocerasin . j .| C,H,NO, 15247 | 57914023 | 153 Laurostearic acid . » C2H3.0, 72°09 | 12-04 | 15'87 Lecanorie acid j C,sH1407 60:37 | 4:40 | 35°23 Legumin j F ; ? 51'47 | 7:02 |24°29 | 16°82 | 040 Levaln. x...) &ENO, |a4aa| 617 |49:39 Leueine . : . .| C;H,NO, 154°96 | 9:92 | 24-43 | 10°69 Liehenm: . . .| GH.0, A444 | 6-17 |49-39 Lichen-starch j 5 C,H, 005 4444 | 6'17 |49°39 Lignin (cf. p. 256). Limain . . O,Hy0, 16638 | 6:48 | 27-23 Linin . . 4 b l 6292 | 472 | 3236 Lupinin (glucoside) | Cy9H2OL 15463 | 5°47 | 39-90 Luteolin . . 5 C.H;0, 62°07 | 3°45 | 34'48 Maclurin ‘ . ; C,;H1208 56°25 | 375 | 40:00 Maleic acid . . f 4H,0, 4138 | 3°45 |55°17 Malieaidd . . .| CH,O, |835'82 | 4-48 | 59-70 Maltose Re .0.: 14210 | &43 151.47 Mannite i . : C,H,40% 39:56 | 769 | 5275 Meconic acid . . . C,H,O, 42°0 20 |56°0 Meconin R . . C,H 61'855 | 515 |33°00 262 PERCENTAGE COMPOSITION OF CONSTITUENTS. NAME. Melanthin . Melezitose Melissyl alcohol Melitose Menispermine Menthol Menyanthin . Metarabic acid Methyl alcohol Methylamine Methylconiine Methystiein Milk-sugar Mongumic acid Morphine Morin Moschatine Mucedin Muscarine Mycose . Myristie acid . Myronic acid. * Nareeine Narcotine Naringin Nataloin ; Nepaline » Nicotine . Nuceite . Oak-bark kannid aold Oenanthic acid Oleie acid Ononin Orein R Orsellie acid . Östruthiin Oxalic acid Oxyacanthine P=oniofluorescin Palmitic acid Papaverine Pararabin Parellic acid . Paracotoin Paricine Paridin . Parillin . Paytine.. Peucedanin Philyrin Phlorizin Phloroglucin . Physalin Physostigmine Phytosterin Pieropodophyllin Picroroccelline Picrotoxin FORMULA. C.H307 2 H901 sotteg C,5H30,1 CsH5,N50, 10H CyH30, 1,H501 4 CH,N C,H,,N ? C.H30,1 1210.24 O,H9NO; 151047 C,H3NO, ’ C;H1,NO, CH30,, 14 2805 CH NS5010 N N C.,H,,NO, CH 35015 CH, 36-49 12 C.H14Na Os, 34-11 Cy HNO; 12H140; 62 624 4210 8219 4210 7200 76'983 5546 42:10 37:50 3871 77:69 65°85 4210 66°0 71:58 59:61 6822 5411 5042 42'10 73:68 31'83 5963 6392 55°6 59:44 63:09 7408 40:00 53'85 6412 16:59 59:80 6776 57'15 7707 26:66 60:57 71:38 75°00 17079 42:10 60°67 67°'85 1559 57'83 60°4 7974 7058 60°67 56°15 5713 6364 65°49 8387 6771 68:08 60:50 H, 9:0 643 1415 643 8:00 1282 7:56 643 12:50 16°13 12°23 564 643 46 667 331 6:66 [SV ENe] — RATNASTM HB SUN OUNM LO 00 =T DRAW IMO © mo 0 MA SI 00 & 9:35 4:42 413 11'02 8:86 15'27 0:88 1699 PERCENTAGE COMPOSITION OF CONSTITUENTS. 263 NAME. FORMULA. C. H. | 0. N, S. Pilocarpine . j .| CH, N,0, | 6418 1 |14'89 | 1302 Pimaric acid , : : C„H»0 7947 3 |10°59 Pinipierin , | I OH 5546 6 | 36°98 Pinite . f 5 : C;H,50; 439 489 Piperine 5 5 | GCyrHıNO, 17158 16°84 | 491 Pipitzahoic acid . : C5H203 7258 1936 Populin . f i | CH 01 | 5634 3756 Propionie acid . » C,H,0, 48:65 43:24 Propyl alcohol r . 0,H,;0 6000 | 13° 2666 Protocatechuie acid ‘ C,H;0, 54:54 4156 Purpurin - s \ C,,H,0, 6562 Pyrocatechin . \ : C,H,0, 65°45 Pyrogallic acid . ö C,H,0; 5713 ANTURRRAONAEITSAMNWWWOROANNONT ILEDBHMSOWOSARDOSANHHISSHAUSADmAoODO eK & SON ANAAWSDTHOon— I) =) fe) N) Quassin . ; b | CyH10; 66°67 27:66 Quercetin , » | C35H,0, 59'21 3684 Quereite » . . C,H0; 43°9 489 Quereitrin . N .| CsEl140g 5590 8:75 Quinamine . . -| CüHs4N50, |73°08 10°25 | 8:98 Quinine and Quinidine .| C„H,,Ns0, |75'02 10'43 | 864 Racemic acid. . C,H,0, 320 640 Rhatania-red . - C,H120;5 62:17 1 |33°02 Rhatania tannic acid C4H50; 5940 5 | 35°65 Resorein ; ’ b 6H60; 65°45 6 | 29:09 Rhinacanthin e :| Cu4H304 (D) | 67°20 0 | 25°40 Rhaadine HNO, |65'79 8 125°08 | 3°65 R «I Os Rieinoleic acid : . (& Roccellie acid & C © Rottlerin f ; 90H 3404 71:00 |10'05 | 18°95 Ruberythric acid . »| _ OggH65051 54:64 | 5'04 | 4032 Rubian . ‘ | | CH; (?) |55°08 | 5°57 | 39-35 Rubichlorie acid . «| C14H1s0, (2) |51°22 | 4°88 | 4390 Sabadilline . : .| C,,Hg6N5073 (2) | 61'29 | 8:85 | 2640 KO: 3-46 Sabatrine . . | (uHsNoOır [61:69 | 8-78 12676 | 277 [7 ” C;H Salicin . . 1807 54:54 | 6°29 | 3917 Salicylie acid . ’ : C,H,0, 60:87 | 442 | 34:78 Salicylous acid ; : C,H;,0; 68'85 | 4'92 | 26°23 Sanguinarine . j .) CyHı,NO, 17059 | 5°26 11982 | 4:33 Santalin | 08140, (9) 65-69 | 5-11 | 29-20 Santonin i | O,H150; 13'17 | 732 |19°51 Saponin ’ : .) O.H0 (2) [554 | 7°6 | 836-9 Scleromuein , i ? 29:67 | 644 ? 641 | (26°8 ash Scleroxanthin s . CuH100% 61°8 5:1 |32°0 Sclerotic acid, . ? 40°0 52 |50°6 4'2 Scoparn . . .| 0,H20,(2) |58:06 | 5:06 | 36-87 Sinalbin . f «| OH, 4No8,018 | 4787 | 5°85 |34°05 | 372 | 8-51 Sulphocyanide of sinapine Cj,Hs,N.SO, |55°43 | 6°53 12174 | 7°61 | 8:69 Sinistrin j : eH100; 4444 | 6'17 |49°39 Socaloin f . . GoHsO, 59:63 | 5°59 | 3478 Solanine - : | C.Hg,NO,), |60°66 | 8:78 | 28:88 | 1:68 Sorbin . . 2.1 &Hn0s 40:00 | 6-66 | 53-34 Sparteine . » j C;H,;N 78:06 | 1OB7 | .... 11688 Staphisagrine , ; | CuH%»NO, 1675 84 |20°5 3°6 Starch re s 5 C,H, 0; 44:44 | 617 | 49:39 Stearic acid . | O2H30, 76:06 | 1268 | 1126 Strychnine , i | O,H.N,0, [7724 | 6:54 | 730 | 8-92 Styraein : . ; CjsH1603 81:82 | 6°06 |12'12 Styrol . P . f C;H, 9231 | 7°69 264 PERCENTAGE COMPOSITION OF CONSTITUENTS. NAME. Suceinic acid . Syringin Tannaspidic acid Tannin . Tartaric acid . Terpene, ‘ Thebaine Theobromine . Thevetin Thyujin . Thymol . Trimethylamine Triticin . Turpethin . Tyrosin . . Umbelliferon . Usnic acid Valerianie acid Vanillin Veratrine Veratroidine . Vitellin (Brazil nut) Vulpie acid Xanthorhamnin FORMULA. 0,H,0, O,9H550; O5;H 33011 PD} a PD A020 «| CoHıe O;H34 and O,,H3s CH, NO; C,H;N,O, 81024 66029 265 COMPOSITION OF THE MORE IMPORTANT CONSTITU- ENTS OF PLANTS, ARRANGED ACCORDING TO | PERCENTAGE OF CARBON. 2:22 526 5.04 4:00 4:48 606 417 12:50 1613 870 820 7:69 6'66 52 5:09 345 345 Sn Ho oO [oV} SRrWOHNSDo HNNoDmDco NOW jan DHD © Ho SI00 jet NINRRERNSTOSOOSMHDMNWEnM MN Or DOoSÄWonsaoaVbuHHmmkHeh > 00ND oo 10-37 51-85 3111 372 28:86 157 222 18:37 177 161 16:82 18:09 851 0-45 0:8 0-40 1:32 NAME. Oxalic acid. Glyeolie acid. Myronic acid. Tartaric and racemie acıd. Malie acid. Asparagine. Citrie acid. Methylic alcohol. Methylamine. Glycerin. Erythrite. Duleite, isodulecite, mannite, etc. Acetic and lactic acid, glu- cose, etc. Sclerotie acid. Suceinie acid. Aconitie acid. Fumaric and maleic acid. Meconic acid. Arabic and metarabie acid, pararabin, triticin, saccha- rose, etc. Kinie acid. Pinite and quereite, Boheic acid, Betaine. Hydrocyanic acid. Cyclopin. Cellulose, dextrin, inulin, levulin, sinistrin, starch. Cinchona-tannic acid. Chelidonice acid, Theobromine. Sinalbine, Propionic acid. Caffeine. Choline. Indican. Conglutin, Muscarine. Glutencasein, Ericolin. Fraxin. Rubichloric acid. Legumin. Cinchona-tannice acid. Vitellin, 266 COMPOSITION OF IMPORTANT CONSTITUENTS. C. El; O. N, S. NAME. 5239 478 42:83 er Er Daphnin. 52:42 3:56 4402 - u Gallotannic acid. 5245 681 DO]! 15:65 08 Albumin. 5247 579 40'23 153 er Laurocerasin, 5251 591 3852 3:06 EN Amygdalin. 5253 7:38 40'27 Re ix; Helleborein, 52:60 700 21°49 18:06 0:85 Gliadin. 52:86 | 484 | 42:30 Er = Thujin. 529 52 419 ie ” Apiin. 53-21 7:60 39:19 a RN Digitonin. 53'383 5:19 4148 = 18 Cinchona-red. 587 61 40°2 Ir > Arbutin. 5385 5.13 41°02 er a Oak-bark tannic acid. 53:91 8:59 3750 er an Convallamarin. 54:08 472 4120 er, es Datiscin. 5411 690 2148 16°63 0:88 Mucedin. 54.54 3:90 41'56 En Se: Protocatechuic acid. 5455 9:09 36°36 A net Butyric acid, 5454 629 39:17 N BR Salicin. 54:63 547 39:90 RER, Er Lupinin, u 5464 5:04 4032 en er . Ruberythrie acid. 5477 5:39 39:84 = RER Hesperidin. 5481 673 38°46 we er Syringin. 5487 737 37:50 BE ee Convolvulin, 54'96 9:92 24-43 10:69 En Leucine. 55-08 557 39:35 ar en Rubian. 5529 7'83 36'87 u er Cyclamin. 554 76 36°9 08 er Saponin. 55.43 6°53 2174 761 8:69 Sulphoeyanate of sinapine. 5546 7:56 36:98 a: res Menyanthin. 55°46 756 36°98 Br a Pinipicrin. 55°6 5°6 388 “es as Naringin. 5581 6:99 372.0 A Er Crotonie acid. 55°63 1:98 4238 Bon es Ellagie acid. 55:90 435 3975 Bi a Quereitrin. 56.14 643 Bl 2. er Coniferin, „5615 581 38:05 2 Br Phlorizin. 56'25 875 40:00 Sn 2 Maclurin. 5634 610 37'56 I Rs Populin, 5637 6:04 37:59 36 2: Ipecacuanha-tannie acid. 5666 lat 35°57 ee. Ir Jalapin and turpethin. 56:75 5-41 3784 ur “ COaffeo-tannic acid. 56°75 5-40 37'85 B; A Carthamin. 57:13 476 38-11 25 Pe Phloroglucin, pyrogallol, ete. 5715 4:76 38:09 RR : Orsellic acid. 5732 701 35°67 En D Globularin. 5757 5.12 3496 1:50 085 Cathartie acid. 57'64 742 3494 a Dulcamarin. 57:69 13°46 1538 13:46 Sa Amanitine, 58:00 5:06 36°87 en in Scoparin. 58:06 7'53 3441 Di en 'Thevetin. 58:22 5:50 3628 wi yo Curacao-aloin, 58:23 4:64 3713 BR is Chrysorhamnin, 58:24 738 34:38 23 = Cainein. 58:82 9:80 8187 Zn B Valerianie acid. 5921 391 36'84 23 Sr Quereetin, 59:26 Ha 84:57 n N. Capaloin. COMPOSITION OF IMPORTANT CONSTITUENTS. 267 59.34 5944 59:40 59:39 59:63 59:63 59:66 59:78 59:80 59:92 5995 60:00 60:00 60:00 60:00 60'37 6040 60'46 60:50 60:53 60:57 60:66 60:67 60°67 6071 60:81 60°85 6086 60:90 61:02 61:03 61:29 61:39 61:44 61:69 61'8 61'85 6186 62:01 62:07 62:07 62:17 62:17 6233 624 6246 62:50 62:68 62:92 63:00 63:09 6313 6316 63:44 63:57 63:60 63:64 eK) DORSOTNNTRSTRRBOmMmı< SUOUODP ON Hm SoOW@OOonm—T DAaı©9 415 4:42 1:68 212 438 Everninic acid. NAME. Nataloin. Rhatania-tannic acid. Usnic acid, Socaloin. Narceine, Tyrosine, Colocynthin. Ononin. Glycyrrhizic acid. Digitalin. Angelie acid. Bryonin. Cetraric acid. Propylie alcohol. Lecanoric acid. Parillin. Tannaspidiec acid, Picrotoxin, Colchicine. Oxyacanthine. Solanine. Parellie acid. Philyrin. Barbaloin. Gyrophorie acid. Gardenin. Salieylic acid. Catechin. Trimethylamine, Jervine. Sabadilline, Aconitine., Evernic acid. Sabatrine. Scleroxanthin, Meconin. Benzohelicin. Cinchona-nova-red. Caproie acid. Luteolin. Gratiolin. Rhatania-red, Crocin. Melanthin. Catechu-tannic acid. Anemonin, Antiarin, . Linin. Cnicin. Nepaline. Vanillin. Convallarin, Colchiceine., Hamatoxylin, Digitoxin, Physalin, 268 COMPOSITION OF IMPORTANT CONSTITUENTS. C. H, O. N: S. NAME. 63°83 638 2976 a Be Coriamyrtin. 63°8 82 249 Bu RR Veratroidine. 63:92 07 2712 3:39 “ Narcotine. 64:12 11:44 2444 7 3% Oenanthic acid. 6420 617 29:63 A: AN: Filiein. 6423 877 2700 ae er Ceric acid. 6442 870 2397 2.91 Er Veratrine. 64:48 440 3120 Ei Br Kämpferid. 64:55 8:66 23-47 3:42 en Delphinine. 64:80 13-51 2162 Me is; Butylic alcohol. 6490 76 27°5 3 5 Cäilcedrin. 65.11 3:87 31:02 © na Gentisin. 6526 666 28:07 En ER Kosin. 65'28 5:60 29:03 2% ie Columbin. 65°45 5:16 29:09 er Br Pyrocatechin, hydroqui- none, resorcin, etc. 65:49 7:64 11:60 15-27 a Physostigmine. 6562 313 3125 ui RER Purpurin. 65:69 all 29:20 De er Santalin. 6579 548 25:08 3:65 7 Rhosadine. 6585 5.64 28-51 ex Rr Methysticin. 65:97 575 20:95 733 M Chlorogenine. 66°0 46 29.3 day = Mongumic acid. 66°05 8:26 25:69 ER % Laserpitin. 6638 638 2723 EN a“ Limonin. 6644 6:57 2215 4:84 ER Cocaine. 6666 9:63 2371 Be ie Hederie acid 6666 371 29:63 ER er Umbelliferon. 66°67 6:67 2666 vn Br ‚Quassiin. 6667 370 30:63 u 5% Emodin. 66°98 6°98 26:04 er u, Athamanthin. 6700 9:64 16'390 710 Br Gelsemine. 6711 543 2746 er RR Brasillin. 67:12 1189 1119 979 na Conhydrine. 6720 720 2540 es en Rhinacanthin. 6741 562 29:96 BE 14 Cubebin. 6741 5-62 29:96 “er 1 Curcumin. 675 84 20°5 3:6 RR Staphisagrine. 676 4'2 28:2 er ne Frangulic acid. 6771 588 2641 u. er Picropodophyllin, 6776 645 25-81 Dr ee Orein. 67'85 357 28:58 Err Be Paracotoin. 68:06 5:08 1432 12:34 in Chelidonine. 68:07 5.04 26:89 “ 5 Erythrocentaurin. 68:08 6:31 17:05 8:56 Rs Picroroccelline. 68:22 6°66 27:65 345 RR, Moschatine. 68:39 174 16.58 725 a Ditaine. 68°85 4:92 2623 25 Do Salicylous and benzoie acid. 68:96 8:04 23:00 5 er Elaterin. 69:56 724 23:20 RR mr Betaorein. 69:72 542 2486 er =; Alkannin. 6976 1162 18:61 or ur Capric acid. 69:84 476 25°39 ae a Ootoin. 70:00 9:29 2071 Be 4 Capsaicin. 70:05 6:59 16'25 7% u Cusconine and aricine. 7038 8:50 2112 Br ner Absinthiin. 70:58 795 1660 4:84 ee Atropine, hyoscyamine, etc. COMPOSITION OF IMPORTANT CONSTITUENTS, 269 NAME. Peucedanin, Sanguinarine, Papaverine, Chrysopierin (vulpie acid). Atherospermine. Chrysophanie acid, Delphinoidine, Rottlerin. Pz&oniofluorescin. Morphine and piperine, Berberine. Menispermine (?) Laurostearic acid. Codeine. Chrysarobin. Heptyl-alcohol. Ricinoleie acid. Pipitzahoie acid. Harmaline, Cinnamic acid, Quinamine, Santonin, eugenol, eugenin. Indigo-blue. Berberine and thebaine. Harmine. Bryoidin. Caprylie alcohol, Cytisine. Myristie acid. Coumarin, Nicotine, Chlorophyllan. Asclepin. Aspidospermine. Grönhartin, Bixin, Alizarin, Palmitie acid, (uinine and quinidine. Anacardie acid. Paricine, Helleborin, Stearic acid. Oleic acid. Coniine, Helenin, Arachie acid, menthol, capric aldehyde. Östruthiin, Strychnine. Cinchonine and cinchoni- dine. Methyleoniine, Borneol. Sparteine, Conessine, Aribine, 270 COMPOSITION OF IMPORTANT CONSTITUENTS. C. 78:57 78:68 78:94 79:02 79:24 7947 7974 80:00 80°25 80:67 81:08 8151 8181 81:82 81'82 82:19 82:44 8257 83'49 83:87 8411 8437 88:24 92:31 H. 9:52 1395 10°53 13:17 5:65 9:93 633 9:33 9:55 588 811 1321 1414 6°06 1104 1415 2] 11'36 1178 1183 1215 9:37 11:76 769 Nr 8:86 5.28 NAME. Abietic acid. Cetyl-alcohol. Camphor and caryophyllin, Cerotic acid. Benzaldehyde, Pimaric acid. Paytine. Thymol and carvol. Cardol. Cinnamein. Anethol. Curarine. Cerotyl-alcohol. Styraein and cinnamic aldehyde. Euphorbone and lactucerin. Melissyl alcohol. Hydrocarotin. Betulin. Amyrin. Phytosterin. Cholesterin. Carotin. . Caoutchouc, terpenes, etc. Styrol, INDEX, Abietite, 225 Absinthiin, 49, 146 Acacia, tannin of, 162 Acid, abietic, 127 acetic, 23, 24, 119, 226 aconitic, 70 acrylic, 24, 119 anacardic, 146 angelic, 13, 24, 119 anthemic, 146 arabie, 76, 210, 211, 250 arachic, 15 aspartic, 206 atranoric, 151 beberic, 146 benzoic, 32, 33, 35, 49, 226 beta-erythric, 151 boheic, 160 butyric, 35, 119 caffeic, 161 caffeo-tannic, 161 cambogic, 135 capric, 13, 119 caproic, 13, 119 caprylic, 13, 119 carbusnic, 150 catechuic, 41, 44, 156 N estimation, 157 catechu-tannic, 156 cathartic, 86, 248 cathartogenic, 248 celastrus-tannic, 163 cetraric, 151 chelidonic, 148 chrysophanic, 36, 132 einchona-nova-tannic, 163 einchona-tannic, 162 eincho-tannic, 162 cinnamic, 25 eitric, 70 „ estimation of, 226, 228 „ reactions of, 226 crotonic, 119 diorsellic, 149 ellagic, 153 Acid, ellago-tannic, 160 erythric, 151 evernic, 150 everninic, 150 formic, 23, 24, 119, 226 filix-tannie, 162 frangulie, 133 fumaric, 70, 232 gallic, 32, 133, 226 „ detection and estimation, 47, 137 gallo-tannie, 160, 226 er estimation, 159 gelsemic, 205 glutamic, 207 glycolic, 233 glyeyrrhizie, 171 gummic, 210 gyrophoric, 150 helianthic, 170 hydrocarbusnic, 151 hydrocyanic, 24, 29 isobutyric, 119 jalapic, 140 jervic, 148 kinic, 232 lactie, 232 laurie, 13, 112 lecanoric, 149, 151 leditannic, 163 lichenostearic, 151 linoleic, 11 „ estimation, 111 lobarie, 151 maleic, 232 malic, 70, 229, 234 „ detection, 225 meconic, 148 melangallic, 137 melilotic, 108 metapectic, 211 metarabic, 88, 209, 211, 235, 243 metatungstic, 56 methylerotonic, 13, 119 methylsalicylic, 30 272 Acid, mongumic, 127 morintannic, 158 myristic, 15, 16, 112 myronic, 165 nitric, 78 „,„ estimation, 83, 84, 85 nueitannic, 163 octylic, see caprylic cenanthic, 119 oleic, 11, 112, 113 „ detection, 18 „ estimation, 111 ophelic, 147 orsellic, 149 oxalic, 70, 91, 230 oxyusnetinie, 150 palmitic, 18, 112 para-oxybenzoic, 35, 36 parellic, 150 patellaric, 150 pectic, 211 pelargonie, 13 phosphomolykdic, 56 phosphoric, 226, 229 phyllic, 127 picric, 5€ pimaric, 127 pinie, 127 pipitzahoic, 136 podocarpic, 127 podophyllic, 139 polygonic, 149 polyporie, 90 propionic, 119 protocatechuic, 35 pteritannic, 163 quereitannic, 161 quinic, see kinic quinovie, 175 racemic, 70, 229 rhatania-tannic, 157 ricinoleie, 19 roccellic, 149 ruberythric, 134 rubichloric, 232 rufigallie, 137 salicylic, 24, 32, 33, 49 salicylous, 24, 29, 168 santonic, 36 (see also *santonin ’) sclerotic, 86, 248 stearic, 18, 112 stictic, 151 succinic, 230, 231 sulphuric, 226 sylvic, 127 taigusic, 136 tannaspidic, 162 tannic, 56 tartaric, 71 h estimation, 228 INDEX, Acid, toxicodendric, 24 trimethylacetic, 119 usnic, 150, 152 valerianic, 13, 24, 35, 119 viridic, 161 vulpie, 150 Acids, 225 amidic, 247 estimation of in fruits, 71 examination for, 65, 69 examination of substances soluble in, 91 extraction with, 91 fatty, identification of, 120 „ sSeparation from resin, 112 lichen, 149 mineral, estimation of, 71 = tests for, 71 organic, estimation of, 69 produced by alkalies, 36 qualitative separation of, 70 resin, 32, 127 tannic, estimation of, 41-47 volatile, 23, 29, 117 „ separation of, 119 - Acolyctine, 58 Aconine, 58 Aconitine, 50, 179, 181 estimation of, 60 Acrinyl, sulphoeyanate of, 166 Adansonin, 146 Aesculetin, 169 Aesculin, 49, 169 Agrostemma githago, saponin in, 68, 69 Albumen, estimation of, 79, 80, 238 soluble in dilute soda, 88 vegetable, in mucilage, 66 Albumenoids, detection of, 78 estimation of, 234, 236, 237 examination for, 65, 78 extracted by dilute acid, 240 extracted by pepsin, 240 extracted by spirit, 241 extraction of, 78 insoluble in dilute soda, 89 microchemical, detection of, 78 nitrogen in, 234 not precipitated by alcohol, 76 reagents for, 79 soluble in dilute soda, 88, 235 Alchornin, 146 Alcohol, examination of substances soluble in, 38 extraction with, 38 amyl, 30 cerotyl, 13, 110 cetyl, 13, 110 melissyl, 13, 110 melyl, see melissyl INDEX. Alcohol, octyl, 30 Alcohols, boiling points of, 30 Aleohols, primary, secondary, ete., 30 Aldehyde, angelic, 29 benzoic, 25 capric, 29 cinnamic, 25, 29 methyl-capric, 29 pelargonic, 29 salicylic, 25, 29 Aldehydes, detection in ethereal oils, 29 Alder, tannin of, 156 Aleurites laccifera, wax from, 110 Aleurone, 236 Algarobilla, tannin of, 159 Alızarin, 133 Alkaloid, amorphous, separation from cinchona, 194 of celandine, 50 of eschscholtzia, 204 of pimento, 50 Alkaloids, 178 colour-reactions of, 178, 179, 180 confirmatory tests for, 57 decomposition by alkalies, 58 estimation of, 58, 63, 182 examination for, 50, 51 extracted in fixed oil, 19 extracted with alcohol, 38, 48 extracted with ether, 33 extracted with petroleum spirit, 20 extraction from aqueoussolution,49 group-reagents for, 55 isolation of, 55 microsublimation of, 181 not separated by shaking, 57 of cinchona, 198 hs rarer, 198 55 separation, 194 platinum and gold salts of, 181 quantitative separation, 194 separation, 63, 189 separation by precipitation, 193 separation by solvents, 191 tests for, 181 volatile, 50 Alkannin, 135 Almond, oil of sweet, 102 Aloe-resin, 177 Aloes, valuation of, 177 Aloins, various, 176 Alstonine, 203 Amanitine, 205 Amides, 205 Amido-compounds, 82 Amidulin, 249 Amines, 244 estimation of, 245 Ammonia, estimation of, 81 1) I = Ammonia, examination for, 78 Amygadalin, 164 Amylin, 253 Amylodextrin, 250 Amylum, see starch. Amyrin, 109 Analysis, general method, 5 Anemonin, 109 Anemonol, 109 Angeliein, 109, 208 Anhydrides, action of alkalies on, 36 Aniline, 50 Anthochlor, 117 Anthoxanthin, 117 Anthracene, 136 Anthraquinone-derivatives, 127, 131, 136 Antiarin, 175 Antirin, 146 Aphrodzsein, 170 Apiin, 170 Apricots, oil of, 102 Arabin, 210 Arabinose, 218 Arbutin, 167 Argyrssein, 170 Aribine, 203 Aricine, 198 Aristolochia, bitter, 175 yellow, 146 Arnicin, 146 Asaron, 108 Asclepiadin, 146 Ash, estimation of, 7 Asparagine, 82, 206, 207 Aspidospermine, 50, 204 Athamanthin, 145 Atherospermine, 203 Atropine, 50 estimation of, 60, 182 Bablah fruits, tannin of, 160 Beberine, 203 Beech-oil, 102 Belladonnine, 203 Benzohelicin, 169 Berberine, 49 estimation of, 62 Betaine, 205 Betaorein, 152 Betapicroerythrin, orsellinate of, 151 Betulin, 145 Birch, tannin of, 162 Bistort, tannin of, 158 Bitter-almond oil, 29 Bitter principles, 127 extracted by alcohol, 38, 48 lead compounds of, 52 Bixin, 135 Brasillin, 137 18 274 Brucine, 50 estimation of, 61, 183 Bryoidin, 109 Bryonin, 170 Butylalanine, 205 Cacao, 187 Caffeine, 49 estimation of, 186 Cailcedrin, 146 Calabar Bean, estimation of alkaloid, 184 Calabarine, estimation of, 184 Calcium, oxalate of, 91 estimation, 91 microscopical detection, 92 Calendulin, 175 Californin, 175 Calyein, 151 Cane-sugar, 220 Caoutchouc, detection in fixed oil, 11 extraction of, 109 Capsaicin, 109 Capsicin, 109 Capsicum, 49 alkaloid of, 50 Caragheen-sugar, 219 Carapin, 175 Carbohydrates, see under respective names. Carotin, 109 Cardol, 146 Caryophyllin, 49, 146 Carthamin, 178 Cascarillin, 49, 146 Casein, 235 Castor-oil, 102 Catechin, 32, 138 estimation of, 137 Catechu, tannin of, 156 Celandine, alkaloid of, 50 Celastrus, tannin of, 163 Cell-nucleus, 79 Cellulose, 252, 256 estimation of, 96 varieties of, 256 Ceratophyllin, 150 Cerosin, 111 Cerotene, 110 Cevadilla seed, 184 Chamelirin, 172 Chelidonine, estimation of, 62 Chelidonium, estimation of alkaloid in, 184 Chenopodine, 208 Chimaphilin, 147 Chiratin, 147 Chlorogenine, 203 Chlorophyll, 19, 113, 114 estimation of, 115 INDEX. Chlorophyll, extraction of, 19, 32 Chlorophyllan, 114, 115 Cholesterin, 99 detection in fixed oil, 11 detection and estimation, 106 Choline, 205 Chrysarobin, 132 Chrysin, 128 Chrysophyll, 114 Chrysopierin, 150 Chrysorhamnin, 135 Chylariose, 218 Cieutin, 147 Cinchona, amorphous alkaloid of, 191 tannin of, 162 Cinchona-alkaloids, estimation of, 62 Cinchona-nova-red, 163 Cinchona-red, 162 Cinchonidine, separation of, 194 Cinchonine, 49, 50 separation of, 194 Cinnamein, 25 Cinnamyl, cinnamate of, 25 Cniein, 176 Cnicus benedictus, bitter prineiple of, 49 Cocaine, 203 Codeine, 50 Colchiceine, 49 Colchieine, 49 estimation of, 61 Colocynthin, 49, 170 Columbin, 147 Concluding remarks (to Part I.), 97 Conessine, 203 Conglutin, 235 Conhydrine, 50 Coniferin, 167 Coniine, 50 estimation of, 61, 183, 184, 189 Conquinine, see quinidine Convallamarin, 49, 172 Convallarin, 172 Convolvulin, 141 Coriamyrtin, 143, 170 Corydaline, 203 Cotoin, 147 Cotton-seed, oil of, 102 Coumarin, 108 Cratzgin, 175 Crocetin, 171 Croein, 171 Crude Fibre, 257 Crystalloids, 79 Cubebin, 49, 145 Curarine, 58, 179, 194, 202 Curcumin, 135 Cusconine, 198 Cusparin, 175 Cuticular substance, 95, 253 Cutose, 253 INDEX, 275 Cyanophyll, 113 Cyclamin, 172 Cyclopiafluoresein, 163 Cyelopia-red, 163° Cyclopin, 163 Cynanchocerin, 108 Cytisine, 203 Daphnin, 49, 168 Datisein, 170 Delphinine, 50 Delphinoidine, 50 Dextrin, 212 alcoholate of, 213 estimation of, 65, 67, 213 estimation of in cane-sugar, 215 Dextrose, see glucose Diastase, 237 Diethylamine, 244 Digitalein, 49, 143, 173 Digitalin, 142, 173 Digitaliresin, 142 Digitin, 143 Digitonein, 143 Digitonin, 143, 173 estimation of, 69 Digitoresin, 143, 174 Digitoxin, 142 Dimethyloreoselon, 145 Diosmin, 108 Distillation, fractional, 124 Ditaine, 204 Ditamine, 204 Divaleryloreoselon, 145 Divi-divi, tannin of, 156, 160 Dulcamarin, 171, 204 Duleite, 225 Eeboline, 202 Echicerin, 108 Echitamine, 204 Elaidin, test for oils, 102 Elaterin, 49, 147 Emetine, 50 estimation of, 61 Emodin, 132 Emulsin, 237 Ergotine, 202 Ergotinine, 202 Ericinol, 143 Ericolin, 49, 143, 166 Erythrite, diorsellinate of, 151 orsellinate of, 151 Erythrocentaurin, 147 Erythrophyll, 115 Erythrophleine, 202 Erythroretin, 132 Erythrosclerotin, 134 Eschscholtzia, 204 Ethereal Oil, see ‘Oil, ethereal ’ Ethereal Salts, see ‘Salts, ethereal’ Ether, direct extraction with, 36 estimation of substances soluble in, 32 examination of substances soluble in, 81 Etiolin, 116 Ethylamine, 244 Eucalyn, 219 Eupatorin, 147 Euphorbon, 108 Fat-acids, fixed, 14 fractional preeipitation of, 14 free, 105 detection and estimation, 106 melting points of, 14, 15 volatile, 13 Fats, see ‘Fixed Oil’ Fehling’s Solution, 72 Ferments, 237 Fibrin, vegetable, 235 Filix, tannin of, 162 Filiein, 99, 107 Fixed oil, composition of, 10 detection of, 10 elaidin test for, 10 estimation of, 10, 11, 99 estimation of glycerin in, 12 linoleic acid in, 11 oleie acid in, 11 qualitative reactions, 11 resinification of, 101 tests for, 101, 102 Fraxin, 169 Fresh plants, treatment of, 6, 10 Fruit-sugar, 218 Fumarine, 205 Fungin, 253 Galactose, 219 Galls, tannin of, 156, 159, 226 Gardenin, 127 Geissospermin, 49, 204 Gelose, 252 Gelsemine, 50, 205 General Remarks, 1 Gentian-bitter, 140 Gentisin, 139 Geraniin, 176 Glaucine, 205 Gliadin, 241 properties of, 242 Globularin, 170 Globulin, 235 estimation of, 79 Glucodrupose, 256 Glucolignose, 256 Glucose, detection of, 214 estimation of, 72, 73, 74, 215, 217 18—2 276 INDEX. Glucose, fermentation test for, 216 Hydrocarotin, 109 polarization of, 221 Hydrocotoin, 147 Glucoses, detection and estimation, | Hygrine, 203 64, 72 Hyoscine, 60 extracted by alcohol, 38, 48 Hyoscyamine, 50 various, 256 estimation of, 60, 183 Glucosides, detection of, 53 Hypochlorin, 114, 116 direct examination for, 50 extraction of by ether, 33 Incrusting substance, 95, 253 extraction of from aqueous solu- | Indican, 174 tion, 49 Indigo blue, 174 group-reagents for, 54 Indiglucin, 174 solubility of, 164 Indigo white, 174 Glutamine, 82 Inosite, 219 detection of, 207 Introduction, 1 estimation of, 207 Inulin, characters, 87 Gluten, 243 detection of, 66 Glutencasein, 235 estimation and extraction of, 86 Gluten fibrin, 241, 242 examination for, 86 Glutin, 241 Inuloid, 87 Glycerides, 11 Invertin, 237 Glycerin, estimation of, 109 Invert sugar, 218 Glyeyrrhizin, 171 Ipecacuanha, tannin of, 163 Goa-powder, 132 Isoduleite, 225 Gold, chloride of, as alkaloid reagent, 56 | Isophlorrhizin, 169 Granulose, 249 Grape-sugar, see glucose Jalapin, 140 Gratiolin, 49, 172 Jalapinol, 140 Grönhartin, 136 Jervine, 180 Ground nut, oil of, 102 Juniperin, 148 Guaein, 147 Jurubebine, 205 Guarana, 186 Guaranine, 186 Kämpferid, 108 Gum, 208 Kawain, 148 Gum arabic, varieties of, 211 Knoppern-galls, tannin of, 159 Gum, see also ‘Mucilage’ Kosin, 107 Gummicose, 210 Gum-resins, commercial, 129 Lactose, 210 Gypsophila struthium, saponin in, 69 | Lactucerin, 108 Lactuein, 176 Hzmatoxylin, 32, 33, 136 Lactucon, 108 Harmaline, 203 Laserol, 145 Harmine, 203 Laserpitin, 145 Hazel nut, oil of, 102 Laurocerasin, 164 Helenin, 108 Legumin, estimation of, 79, 234 Helianthus, oil of, 102 Leucine, 207 Helleborein, 49, 172 estimation of, 207 Helleborin, 172 Leuceotin, 147 Hemp, oil of, 102 Levulin, 212 Hesperidin, 171 aleoholate, 213 Hesperidin-sugar, 225 detection and estimation of, 67, Homofluoresein, 151 213 Hop-bitter, 147 Levulosan, 220 Hop-resin, 49 Levulose, 218 Hop, tannin of, 156 Lichen-acids, test for, 151 Horse chestnut, tannin of, 158 Lichenin, 249, 251 Humus, 90 Lichens, microscopical examination of, Hurin, 148 ol Hyadrastine, 205 Lichen-starch, 251 Hydrocellulose, 250 Lignin, 95, 252, 253 INDEX. 277 Lignin, miero-chemical characters of, | Mustard, volatile oil of, 166 255 j Lignin, miero-chemical detection of, 95 Ligustrin, 170 Limonin, 171 Linin, 176 Linseed, oil of, 102 Liriodendrin, 148 Literature of plant-analysis, 3 Lobeliine, 50, 202 Loturine, 175, 205 Lupinin, 176 Lutein, 117 Luteolin, 140, 178 Lyecine, 205 Lyeopin, 148 Lycopodine, 205 Maclurin, 158 Maltose, 221 Mangostin, 148 Mannite, 77, 224 Marattin, 70 Marrubin, 148 Masopin, 148 Meconin, 148 Melampyrite, 225 Melanthin, 173 Melanthigenin, 174 Melezitose, 221 Melitose, 221 Melting-points, determination of, 15 Menispermine, 205 Menyanthin, 49, 166 Mercuric chloride as alkaloid reagent, "56 Metacellulose, 253 Methylanthracene, 136 Methylconiine, 50 Methystiein, 148 Milk-sugar, 220 Moisture, estimation of, 5 Monamines, 244 Morin, 158 Morphine, 50 estimation of, 61, 184, 199 Morindin, 135 Morindon, 135 Mucedin, 241, 242 Mucilage, characters of, 210 estimation of, 65 examination for, 65 a method of examination, vegetable, 208 Mudarin, 176 Munjestin, 135 Murrayin, 171 Muscarine, 205 Mycose, 221 Myosin, 235 separation from vitellin, 236 Myrica cerifera, wax from, 110 quereifoli, „ „ 110 species, a Myrobalans, tannin of, 156, 160 Myrosin, 165 Myroxocarpin, 108 Narceine, 49, 50 Nareotine, 50 estimation of, 61, 184, 199 Naringin, 171 Nartheein, 148 Nepaline, 60 Neurin, 205 Nicotine, 50 estimation of, 61, 188 Nitriles, 27 Nitrogen, detection in ethereal oil, 27 estimation of, 80 Nitrogenous substances, 244 Nuein, 148 Nucite, 219 Nupharine, 50, 205 Oil, ethereal, constituents of, 27 detection and estimation of, 21 detection of nitrogen in, 27 detection of sulphocyanogen in, 27 detection of sulphur in, 26 distillation of, 23 estimation of, 117 examination of, 25 examination for aldehydes, 29 fluorescence, 26 fractional distillation, 27, 124 optical tests for, 120 polarization of, 25 reactions of, 26, 121, 122, 123 solubility in alcohol, 26, 120 specific gravity of, 26 stearoptenes in, 28 olive, 102 Öleandrine, 205 Olivil, 176 Ononin, 170 Operations, preliminary, 5 Opium, estimation of alkaloid in, 199 Orein, estimation of, 152 Oreoselon, 145 Östruthiin, 144 ÖOxyacanthine, 205 278 Oxyaloin, 178 Oxyeyclopin, 163 ÖOxyleucotin, 147 Oxyneurin, 205 Psoniofluoresein, 36, 131 Panaquillon, 172 Papaverine, 49, 50 Papayotin, 237 Paracellulose, 253 Paracholesterin, 107 Paracotoin, 147 Paramenispermine, 205 Pararabin, 91 estimation of, 93 Paricine, 199 Paridin, 172 Parigenin, 174 Parillin, 174 Paytine, 199 Pectin, 208 Pectose, 253 Pelletierine, 205 Peptone, 239 Pereirine, 50, 205 Petroleum Spirit, estimation of sub- stances soluble in, 8 Petroleum Spirit, extraction with, 8 Peucedanin, 145 Phoretin, 132 Phaseomannite, 219 Philygenin, 169 Philyrin, 169 Phlobaphene, 88, 90 Phlorogluein, 35 Phlorose, 218 Phlorretin, 169 Phlorrhizin, 169 Phylloeyanin, 113 Phylloxanthin, 114, 116 Physalin, 49, 171 Physostigmine, 50 estimation of, 61, 184 Phytosterin; 107 Picroerythrin, 151 Picrolichenin, 151 Picropodophyllin, 139 Picrosclerotine, 202 Picrotoxin, 49, 142 Pilocarpine, 50 estimation of, 184 Pimento, alkaloid in, 50 Pine, tannin of, 162 Pinipierin, 167 Pinite, 225 Piperine, 49 estimation of, 188 Pittosporin, 170 Platinum, perchloride of, as alkaloid reagent, 56 INDEX. Plumbagin, 149 Podophyllotoxin, 139 Podophyllum peltatum, 139 Polychroite, 171 Pomegranate, tannin of, 160 Poppyseed, oil of, 102 Populin, 49, 168 Porphyrine, 203 Potassiobismuthie iodide, as alkaloid reagent, 55 Potassiocadmie iodide, as alkaloid reagent, 56 Potassiomercuric iodide, as alkaloid reagent 55 Potassium, bichromate of, as alkaloid reagent, 56 Potassium, myronate, 165 tribromide, as alkaloid reagent, 55 Potassium, tri-iodide, as alkaloid re- agent, 55 Powdering, 6 Preliminary operations, 5 Protoplasm, 79 Pseudaconitine, 60 Pseudamyl-alcohol, 30 Punieine, 205 Purpurin, 133 Pyrocatechin, 32, 33, 36, 138 Pyrogallol, 35, 36, 137 Quassiin, 49, 149 Quebrachin, 49 Quercetin, 36, 138 Querein, 176 Quercite, 225 Quereitrin, 36, 138, 178 Quillaja saponaria, saponin in, 69 Quinamine, 198 Quinidine, 50 separation of, 194 Quinine, estimation of, 62, 185 separation from bark-alkaloids, 194 Quinovin, 175 Rape-oil, 102 Ratanhin, 208 Resin, detection in fixed oil, 11 extraction of, 31, 38 micro-chemical detection, 33 separation from fat acid, 112 Resins, 127 acid, 34, 36 „ separation of, 127, 128 action of potash on, 34 anhydrides, 34 behaviour to reagents, 34 commercial, 129 dry distillation of, 36 indifferent, 34 INDEX. 279 Resins, micro-chemical examination, 33 | Sinalbin, 166 oxidation-products of, 34 purification, 34 Resorcin, 35 Rhamnin, 155 Rhamnodulecite, 225 Rhatany-red, 157 Rhatany-root, tannin of, 157 Rhinacanthin, 135 Rhinacanthus communis, 135 Rhinanthin, 163 Rhinanthogenin, 163 Rheadine, 203 Rheaginine, 203 Rhubarb, Assay by Iodine, 248 Rhus succedanea, wax from, 110 Ricinus communis, oil of, 102 Robinin, 140, 178 Rottlerin, 149 Rubiadin, 134 Rubian, 134 Rubiretin, 134 Rutin, 140, 178 Sabadilline, 50 estimation of, 61, 184 Sabatrine, 50 estimation of, 61, 184 Saccharose, Böttger’s test for, 76 characters of, 76 estimation of, 75 examination for, 65, 72 inversion of, 75 Saccharoses, 220 Salicin, 33, 50, 168 Saliein-sugar, 218 Saligenin, 168 Saliretin, 168 Salts, ethereal, 29 Samaderin, 170 Sand, 7 Sanguinarine, 62 Santalin, 137 Santonin, 36, 49 estimation of, 141 Saponaria officinalis, saponin in, 69 Sapogenin, 68 Saponin, 49, 173 estimation of, 68 examination for, 67 Sarracenia purpurea, alkaloid in, 50 Sarsaparilla, saponin in, 69 Scillain, 173 Sclererythrin, 134 Scleromucin, 249 Scleroxanthin, 149 Senegin, 49, 173 Separation, methods of, 3 Sesame, oil of, 102 Sicopirin, 149 Sinapine, acid sulphate of, 166 sulphocyanate of, 166 Sinistrin, 212 alcoholate of, 213 detection and estimation, 67, 213 Sinkaline, 205 Smilaecin, 174 Soda, examination of substances soluble in, 88 Solanidine, 49 Solanine, 50 Sorbin, 219 Sorbite, 225 Sordidin, 151 Sparattospermin, 176 Sparteine, 50, 205 Special Methods, 99 Staphysagrine, 180, 193 Starch, 91, 249 estimation of, 93 Stearoptene in ethereal oil, 28 Styracin, 25 Strychnine, 50 estimation of, 61, 183 Styrol, 108 Suberin, 95, 255 Sugar, estimation by polarization, 221 Sulphocyanogen, detection in ethereal oil, 27 Sulphur, detection in ethereal oil, 26 Sumach, tannin of, 159 Sunflower seed, oil of, 102 Surinamine, 203 Syringin, 49, 170 Syringopicrin, 170 Tampiein, 140 Tanacetin, 149 Tanghinin, 149 Tannin, constitution of, 152 decomposition of, 152, 153, 154, 156 detection of, 39 detection of glucose from, 153 ellagic acid from, 153 estimation of, 41-47 extracted by ether, 31 5, alcohol, 38 extraction of, 40 gallic acid from, 153 glucosidal nature of, 153 insoluble in water, 156 microscopical detection of, 40 purification of, 155 reactions of, 40 separation from alkaloid, etc,, 52 various, 153, 162, 163 Taraxacin, 149 Taxine, 50, 205 280° Tea, 186 tannin of, 160 Thebaine, 50 Tectochrysin, 128 Terpenes, 28 Thalictrin, 180 Theine, estimation of, 62 Theobromine, 49 estimation of, 187 Thevetin, 172 Thujin, 140 Toxiresin, 143 Trehalose, 221 Triethylamine, 244 Trimethylamine, 245 Trimethylaniline, 50 Tritiein, 212 alcoholate of, 213 detection and estimation, 67, 213 Turpethin, 141 Tyrosine, detection of, 208 estimation of, 207 Umbelliferon, 36 Valonia, tannin of, 159 Vanillin, 167 estimation of, 144 Variolinin, 151 Vasculose, 253 Verantin, 134 INDEX. Veratrine, 50 estimation of, 61, 184 Veratroidine, 179, 189 Viola tricolor, 139 Violaquereitrin, 139 Violin, 203 Vitellin, 235 Vitellin, isolation of, 236 separation from myosin, 286 Walnut, oil of, 102 Water, examination and estimation of substances soluble in, 65 mineral matter dissolved by, 65 Wax, Bahia, 111 Carnauba, 111 microscopical detection, 111 vegetable, 13, 110 Wood-gum, 249, 252 Wormseed, estimation of santonin in, 141 Wrightine, 203 Xanthein, 117 Xanthin, 117 Xanthophyll, 114, 116 Xanthorhamnin, 135 Xanthosclerotin, 149 Xylostein, 149 Zeorin, 151 THE END. SD nr \ I \ ) zyurC 07 G y Kr « ÄRELETLEIIZ PL ZEUEEFESPETETFE FF nn nu nee en ee me anne nl ng nn men teren sau it nn ea nenn en ya nn nen run un un His | rm re .. DEREN De Ba ne” er en > NR ee ee