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PLANT ANALYSIS :

QUALITATIVE AND QUANTITATIVE.

BY

G. DRAGENDORFF, PH.D.,

PROFESSOR OF PlfARM ACY IN THE UNIVERSITY OF DORP AT, RUSSIA.

from tijc Qerman

BY

HENRY G. GREENISH, F.I.C.

rrisa CoESego of Pharmacy

LONDON :

BAILLIEEE, TINDALL, AND COX,
20, KING WILLIAM STREET, STRAND.

1884.
[All Rights Reserved.]

3>

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 pharmacists.

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 ' tincture,' 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 ' extract. '

The name * petroleum spirit ' sufficiently indicates the origin of

iv TRANSLATORS PREFACE. V*

the liquid. A petroleum spirit boiling above 60° C. should not
be used. Benzene should boil at 80-81° C. ('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 TKANSLATOE,

LONDON, 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
1 Chemische Werthbestimmung ' the detection and estimation of
the active principles 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 inducing 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 insufficiency 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 A UTHORS PREFA CE.

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 restrict 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 PEE FACE. vii

I have assumed in my readers an acquaintance with the leading
principles 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. I have, 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 IXDEX.

PAGE

INTRODUCTION 1

§ 1. General Remarks, p. 1. — §2. Object of ,the Work ; Division
of Matter, p. 2. — § 3. Leading Principles in the Analysis of
Plants, p. 3
METHOD OF EXAMINATION FOR THE MORE IMPORTANT

CONSTITUENTS OF PLANTS .... 5

I. PRELIMINARY OPERATIONS. ESTIMATION OP MOISTURE AND ASH . 5

§ 4. Drying the Materials, p. 5.— § 5. Treatment of Fresh Plants,
p. 6. — § 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
§ 8. Value of Petroleum Spirit in the Analysis of Plants, p. 8. —
§ 9. Methods of Extraction, p. 8.— § 10. Treatment of Fresh
Aromatic Vegetable Substances, p. 10

EXAMINATION OF THE FIXED OIL . . . . .10

§ 11. Macroscopical and Microscopical Detection ; 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 the same, p. 15. — § 19. Further Remarks
on Oleic, Ricinoleic Acid, etc., p. 18.

CHLOROPHYLL AND ALKALOIDS EXTRACTED SIMULTANEOUSLY WITH

THE FIXED OIL ....... 19

§ 20. Optical Properties and Detection of Chlorophyll, p. 19. —
§ 21. Influence of Fixed Oil in Determining the Solution of
Alkaloids, p. 20.

EXAMINATION OF THE ETHEREAL OIL . . 21

§ 22. Detection and Estimation, p. 21. — § 23. Estimation in the
Presence of Fixed Oil and Resin, p. 22.— § 24. Distillation of
Larger Quantities of Ethereal Oil, p. 23.— § 25. Examination
of the Aqueous Distillate for Volatile Acids, Formic, Acetic,
Acrylic, Toxicodendric, Salicylous Acid, p. 23.— § 26. Salicylic,
Benzoic, Cinnamic Acid, Styracin, Cinnamein and Aldehydes
of above Acids, p. 24. — § 27. Physical Properties of Ethereal
Oils ; Umbelliferone, p. 25.— § 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

SYSTEMATIC INDEX.

PAGE

Constituents, p. 28.— § 33. Aldehydes, p. 29.— § 34. Volatile
Acids, p. 29. — § 35. Ethereal Salts and the Alcohols contained
in them ; Primary, Secondary, and Tertiary Alcohols, p. 29.

III. EXAMINATION OF THE SUBSTANCES SOLUBLE IN ETHER : RESINS

AND THEIR ALLIES . . . . . .31

§ 36. Methods of Extraction ; Fixed Oil, p. 31.— § 37. Chlorophyll,
p. 32. — § 38. Portion of the Ethereal Extract Soluble in Water ;
Haematoxylin, Gallic Acid, Glucosides, Alkaloids, etc., p. 32. —
§ 39. Portion Soluble in Alcohol, p. 33.— § 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, Sulphuric
Acid, Nitric Acid, Bromine, etc., p. 34.— § 42. Action of fused
Potash, Resorcin, 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 ; Pseonio-
fluorescin, Chrysophanic 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 OP THE SUBSTANCES SOLUBLE IN ABSOLUTE ALCOHOL ;

RESINS, 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 OP TANNIN . . . . . .39

§ 49. Detection, p. 39.— § 50. Detection continued, p. 39.— § 51.
Reactions of most Tannins ; Microchemical Detection ; Alcohol
more suitable for their Extraction than Water, p. 40. — § 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, lodic Acid, Iodine, p. 45 ; IX. Caustic
Potash and Atmospheric Air, p. 45 ; X. Cinch onine, p. 45 ; XI.
Hide, p. 46; XII. Gelatine, p. 46.— § 53. Tannic and Gallic
Acid, p. 47
EXAMINATION FOR GLUCOSIDES, ALKALOIDS, ETC. . . .48

§ 54. By the Method of Agitation, p. 48.— § 55. List of Bitter Prin-
ciples, Acids, etc , removable from Acid Solution by Agitation
with Petroleum Spirit, Benzene, Chloroform, p. 49. — § 56. Ex-
traction of Alkaloids from Ammoniacal Solution, p. 49. — § 57.
Direct Test for Glucosides, Alkaloids, etc., p. 50.— § 58. Isola-
tion and Purification of Substances not removable by Agitation ;
Separation from Glucose, etc., p. 51. — § 59. Separation of cer-
tain Glucosides and Bitter Principles from Tannin, etc., p. 52.
— § 60. Decomposition of Compounds of Lead with Bitter
Principles, etc., p. 52. — § 61. Detection of the Glucosidal
Nature of a Substance, p. 53.— § 62. Other Reactions of Gluco-
sides, p. 54.— § 63. Alkaloids not 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. xi

of Theine, p. 62. — § 67. Estimation of Total Alkaloids in
Cinchona, p. 62. — § 68. Acidimetric 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. . . 65

§71. Method of Extraction, p. 65. — §72. Estimation of Total Sub-
stances Dissolved, p. 65.
EXAMINATION FOR VEGETABLE MUCILAGE, DEXTRIN, LEVULIN,

TRITICIN ; SINISTRIN . . . . . .65

§ 73. Detection and Estimation of Mucilage, p. 65. — § 74. Vege-
table Albumin and Tarsoates Present in Mucilage-precipitate,
p. 66.— § 75. Inulin, p. 66. — § 76. Dextrin, Levulin, Sinistrin,
Triticin ; Estimation, p. 67.
SAPONIN AND ITS ALLIES . ... 67

§ 77. Separation from Dextrin, etc., p. 67. — § 78. Estimation,

p. 68.— § 79. Digitonin, p. 69.
EXAMINATION FOR ACIDS . . . . . .69

§ 80. Precipitation with Acetate of Lead, p. 69.— § 81. Malic,
Fumaric, Oxalic, Racemic, Citric, Aconitic, Tartaric Acid ;
Marattin, p. 70. — § 82. Volumetric Estimation of the fore-
going Acids. Free and Combined Acid. Mineral Acids, p. 71.
EXAMINATION FOR GLUCOSES, SACCHAROSES, ETC. . . .72

§ 83. Volumetric Estimation of Glucose with Fehling's Solution ;
Gravimetric Estimation with Copper, p. 72. — § 84. Knapp's
Method ; Sachsse's Method, etc., 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. Distinctive 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,
p. 77.
EXAMINATION FOR ALBUMINOIDS SOLUBLE IN WATER, AMMONIA,

AMIDES, NITRIC ACID ...... 78

§ 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. (b) From the Nitrogen, p. 80.— § 97. Estimation of Am-
monia,p. 81.— § 98. Amido-compounds, p. 82.— §99. Estimation
of Nitric Acid (a) by Schulze's Method, p. 83.— § 100. (6) By
Wulfert-Schloessing's Method, p. 85.— § 101. Sclerotic and
Cathartic Acid, etc., p. 86.
EXAMINATION FOR INULIN . . . . . .86

§ 102. Characteristic Properties of Inulin and Inuloid, p. 86.
VI. EXAMINATION OF THE SUBSTANCES SOLUBLE IN DILUTE SODA :

METARABIC ACID, ALBUMINOIDS, PHLOBAPHENE, ETC. . 88

§ 103. Method of Extraction, p. 88. — § 104. Detection and Estima-
tion of Albumen, p. 88. — § 105. Estimation, p. 88. — § 106.
Nitrogenous Substances not dissolved by Dilute Soda, p. 89. —

xii SYSTEMATIC INDEX.

§ 107, Mucilaginous and Albuminous Substances, Phlobaphene,
etc., not Precipitated by Acids, p. 89. -§ 108. Phlobaphene,
Polyporic Acid, Humus, etc., p. 90.

VII. EXAMINATION OP SUBSTANCES SOLUBLE IN DILUTE HYDKOCHLOKIG

ACID ; STARCH, PARARABIN, OXALATE OP CALCIUM, ETC. . 91

§ 109. Extraction, p. 91.— §110. Estimation of Oxalate of Calcium,
P. 91. — § 111. Estimation of Oxalate of Calcium and Pararabin,
p. 92.— § 112. Estimation of Pararabin, p. 93.— § 113. Estima-
tion of Oxalate of Calcium and Starch, p. 93.— § 114. Estima-
tion of Oxalate of Calcium, Starch, and Pararabin, p. 93.—
§ 115. Estimation of Starch, p. 93.

VIII. ESTIMATION OP LIGNIN AND ITS ALLIES, AND OF CELLULOSE . 95
§ 116. Lignin, Incrusting and Cuticular Substances, Suberin,

p. 95.— § 117. Estimation of Cellulose, p. 96.
CONCLUDING REMARKS . . . . . .97

§ 118. Remarks on the Method of Analysis recommended,

p. 97.— § 119. On the Object of Plant Analysis, p. 97.
SPECIAL METHODS ; SUPPLEMENTARY NOTES, ETC. . 99

FATS AND THEIR CONSTITUENTS, CHOLESTERIN, FlLICIN, ETC. . 99

§ 120. Estimation of Fat in General ; Apparatus for Extrac-
tion, p. 99.— § 121. Resinification, p. 101.— § 122. Elaidin-test,
p. 101.— § 123. Behaviour to Sulphuric Acid, p. 102.— § 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, Lactucon, Lactucerin,
Echicerin, Cynanchocerin, Helenin, Coumarin, Melilotic Acid,
Styrol, Myroxocarpin, Diosmin, Kampferid, 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.
§ 130. Estimation of Oleic Acid, Linoleic Acid, Laurie Acid ;
Separation of the latter from Oleic and Myristic Acid ; of
Oleic from Stearic Acid, p. 111. — § 131. Separation of Fat-
acids from Resin-acids, p. 112.

CHLOROPHYLL AND ITS ALLIES . . . . .113

§ 132. Remarks on the Chemistry of Chlorophyll, p. 113. —
§ 133. Possibility of Estimating, p. 115.— § 134. Erythrophyll
and Chlorophyllan, etc., p. 115. — § 135. Xanthophyll, Hypo-
chlorin, Etiolin, Anthoxanthin, p. 116.

ETHEREAL OILS, VOLATILE ACIDS, ETC. . . . .117

§ 136. Examples of Estimation, p. 117. — § 137. Estimation with
Bisulphide of Carbon, p. 118. — § 138. Mixtures of Fixed
and Ethereal Oils, Resin, etc., p. 118.— § 139. Volatile Acids :
Angelic, Methylcrotonic, Capric, Caprylic, (Enanthic, Cap-
roic, Valerianic, Butyric, Propionic, Acetic, Formic Acids and
their Separation, p. 119.— § 140. Identification of Volatile
Acids by Saturating Power, etc., 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.

SYSTEMATIC INDEX. xiii

PAGE

RESINS, ANTHRAQUINONE-DEKIVATIVES, GALLIC ACID, BITTER PRIN-
CIPLES, ETC. .... .127

§ 145. Coniferous Resin-Acids ; Podocarpic Acid, Phyllic Acid,
Mongumic Acid, Paeonia acid, Chrysin, etc. ; More important
Methods of Isolating Resin-Acids, p. 127. — § 146. More im-
portant Commercial Resins ; Estimation of Ethereal Oil,
Mucilage, etc., p. 129. — § 147. Paeonio-fluorescin, p. 131. —
§ 148. Anthraquinone-derivatives, Chrysophanic Acid, Chry-
sarobin, Emodin, Frangulic Acid, Alizarin, Purpurin, Scler-
erythrin, Ruberythric Acid, Rhinacanthin, Alkannin, Bixin,
Curcumin, etc., p. 131. — § 149. Recognition of Anthraquinone-
derivatives, p. 136. — § 150. Hsematoxylin, Brasillin, Santalin,
p. 136.— § 151. Gallic Acid, Catechin, Pyrocatechin ; Detection,
Estimation, etc., p. 137. — § 152. Quercitrin, Quercetin, Thujin,
Rutin, Robinin, Luteolin, Gentisin, Constituents of Podophyllin,
p. 138. — § 153. Jalapin and Allied Resin-glucosides ; Con-
volvulin, Tampicin, Turpethin, etc., p. 140. — § 154. Santonin ;
Estimation, p. 141. — § 155. Picrotoxin, Digitalin, Digitoxin,
Digitalein, Digitonin, Digitin, Coriamyrtin, Ericoiin, Vanillin
(Estimation), Ostruthiin, Peucedanin, Oreoselon, Athamanthin,
Laserpitin, Cubebin, Betulin, Anacardic Acid, Cardol, p. 142.
§ 156. Other Bitter Principles Soluble in Ether ; Absinthiin,
Elaterin, Hop-Bitters, Meconin, Meconic Acid, Methysticin,
Quassiin, etc., p. 146. — § 157. Lichen Acids and their
Allies : Roccellic, Lecanoric, Orsellinic, Gyrophoric, Parellic,
Patellaric, Evernic, Everninic, Usnic, Carbusnic, Vulpic,
Ery thric, Beta-erythric, Cetraric, Lichenostearic, Stictic, Lobaric,
Atranoric Acid ; Ceratophyllin, Picroerythrin, Picrolichenin,
Variolinin, Zeorin, Sordidin, Calycin, etc., p. 149. — § 158.
Orcin and Betaorcin ; Estimation of Orcin, p. 152.

TANNINS . . . . . . . .152

§ 159. Constitution, p. 152. — § 160. Glucosidal Nature or otherwise
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. Cyclopin, Rhinanthin, p. 163.— § 167. Solubility; Description
of the more important Glucosides. Amygdalin and Lauro-
cerasin, Estimation ; Myronic Acid, Estimation ; Sinalbin
(and Sulphocyanate of Sinapine), Menyanthin, Pinipicrin,
Coniferin, Arbutin, Daphnin, Salicin, Populin, Benzohelicin,
Philyrin, Phlorrhizin, ^Esculin, Fraxin, Syringin, Globularin,
Pittosporin, Samaderin, Colocynthin, Bryonin, Ononin, Apiin,
Datiscin, Physalin, Dulcamarin, Hesperidin, Crocin, Glycyr-

xiv SYSTEMATIC INDEX.

PAGE

rhizin, Panaquillon, Thevetin, Chamaelirin, Gratiolin, Paridin,
Convallarin, Convallamarin, Helleborin and Helleborein,
Scilla'in, Saponin, Digitonin, Senegin, Melanthin, Parillin,
Sapogenin, etc., Indican, Indigo-blue, p. 164.— § 168. Non-
glucosidal Bitter Principles, Cusparin, Chinovin, Cnicin, p. 175.
— § 169. Aloins, p. 176.— § I/O. Carthamin, p. 178.

ALKALOIDS ....... . 178

§ 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 Phosphomolybdic Acid ; of Pilocarpine ; Ap-
plication of Phosphotungstic Acid, Tannic Acid, Picric 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.— § 178. Esti-
mation of Piperine, p. 188. — § 179. Volumetric 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, Narce'ine and Narcotine,
Morphine and Codeine, Morphine and Narcotine, Strychnine
and Brucine, p. 189.— § 182. Separation by Solvents ; Strych-
nine and Brucine ; Colchicine and Colchiceme ; Cinchonine
and Amorphous Alkaloid ; Delphinine and Delphino'idine ;
Morphine and Narcotine ; Morphine, Codeine, and Theba'ine ;
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. 193. — § 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. — § 187.
Estimation of the more important Opium-Alkaloids, p. 199.
— § 188. Methods of Procter, Prollius, Fliickiger, p. 200.—
§ 189. Other Alkaloids ; Ergotinine and Picrosclerotine ; Cura-
rine, Erythrophlreine, Lobeliine, Conessine, or Wrightiine, Har-
maline and Harmine, Surinamine, Aribine, Atherospermine,
Rhoaadine, Violine, Beberine, Belladonnine, Cocaine and
Hygrine, Chlorogenine and Porphyrine, Corydaline, Cytisine,
Ditamine, Geissospermine, Aspidospermine, Dulcamarine,
Glaucine* Fumarine, etc., 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 ...... 208

§ 193. Differences in Gum and Pectin, p. 208.— § 194. Modified

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. . . . . 212

§ 198. Distinctive Characters, p. 212. — § 199. Formation of
Alcoholates ; Composition ; Estimation by Titration and
Polarization, p. 213.

GLUCOSES ........ 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-, Salicin-, and Caragheen-
sugar ; Phlorose, Arabinose, Galactose, p. 217. — § 206. Inosite
Sorbin, Eucalyn, Nucite, p. 219.— § 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-
cifce (Rhamnodulcite), Hesperidin-sugar, Sorbite, p. 224. —
§ 213. Mannitan, Quercite, Pinite, Abietite, p. 225.

ACIDS ........ 214

§ 214. Reactions of Malic Acid ; Separation from Oxalic,
Tartaric, Citric, Succinic, Gallic, Tannic, Benzoic, Acetic,
Formic Acid, p. 214.— § 215. Estimation of Citric Acid
as Barium-salt, p. 206.— § 216. Reactions of Citric Acid ;
Aconitic Acid, p. 227.— § 217. Estimation of Tartaric Acid as
Acid Tartrate of Potassium, p. 228.— § 218. Estimation of
Tartaric and Citric Acid when present together ; Separation
from Malic, Oxalic, Phosphoric, and Sulphuric Acid ; Racemic
Acid, p. 228.— § 219. Oxalic Acid ; Separation from Tartaric
and Citric Acid ; Isolation from Oxalate of Calcium, p. 230. —
§ 220. Succinic Acid ; Separation from Oxalic, Tartaric, and
Citric Acid, p. 230.— § 221. Fumaric and Maleic Acids;
Kinic Acid; Rubichloric Acid, p. 232. — §222. Lactic Acid,
p. 232. -§ 233. Glycolic Acid, p. 233.

ALBUMINOIDS, ETC. ....... 234

§ 224. Calculation of Nitrogen into Albuminoids, p. 234. — § 225.
Repetition of Estimation of Legumin, p. 234. — § 226. Casein,
Glutencasein, 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, etc.,
p. 237. — § 231. Estimation of Albuminoids with Acetate of

xvi SYSTEMATIC 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.
AMINE COMPOUNDS ....... 244

§ 239. Distinctive Characters of Monamines, Diamines, etc., p. 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,
Sclerotic Acid, Scleromucin, Assay of Rhubarb, p. 247.
STARCH, LICHENIN, WOOD-GUM, ETC. ..... 249

§ 243. Constituents of Starch, p. 249.— § 244. Constituents of the
Cell- wall that turn Blue with Iodine ; Lichen-starch, p.. 250. —
§245. Lichenin and Gelose, p. 251.— § 246. Wood-gum, p. 252.
CELLULOSE, LIGNIN, AND ALLIED SUBSTANCES . . . 252

§ 247. Researches of Fre'my and Terreil on Composition of Woody-
tissue ; Cuticular and Incrusting Substances ; Modifications of
Cellulose, Lignin (Vasculose, Incrusting Substances), Suberin,
Glyco-lignose, Glyco-drupose, p. 252. — § 248. Composition of
Cellulose, p. 256. — § 249. Properties of the Various Forms of
Cellulose, p. 256. — § 250. Crude Fibre ; Estimation, p. 257.
PERCENTAGE COMPOSITION OF THE CONSTITUENTS OF

PLANTS REFERRED TO 258

COMPOSITION OF THE MORE IMPORTANT CONSTITUENTS

OF PLANTS ARRANGED ACCORDING TO THE PER-

CENTAGE OF CARBON . . . . .265
ALPHABETICAL INDEX . 271

PLANT ANALYSIS:

QUALITATIVE AND QUANTITATIVE.

INTEODUCTION.

§ 1. AN accurate qualitative and quantitative analysis of a plant
or vegetable substance is not unfrequently referred to as one
of the most difficult tasks that a chemist may be called upon
to undertake. Attention is very properly difected 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 difficulties 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. o«jb >whioh. aje equa-ly
important for scientific botaJay ii\d jcKemistrjr, *for m£cKci*i<V phar-
macy, dietetics, agriculture^etc. . Bj systematically . ar

2 §§ 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 microchemical analysis.

With reference to tjie 'ar,vattgemon^ of the matter in the work,
I would remark that in the method of analysis contained in

§§ 2, 3. INTRODUCTION. 3

Part I, 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,1 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.

1 I draw particular attention here to Rochleder's 'Anleitung zur Analyse
von Pflanzen und Pflanzentheilen' (Wiirzburg, 1858), which I regard as open-
ing up new ground in this subject. See also Wittstein, 'Anleitung zur
chemischen Analyse von Pflanzentheilen' (Nordlingen, 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 Analysis immediato de los Vejetales' (Buenos
Aires, 1869) ; and a paper by Parsons in the American Chemical Journal,
vol. i. No. 6.

1—2

4 § 3. 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 MOEE IMPORTANT
CONSTITUENTS OF PLANTS.

I

PRELIMINARY OPERATIONS. 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 hygroscopic 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 suffice, 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

1 An apparatus for drying material for agricultural (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). Tor 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 stibstance. See also Keischauer 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. — If 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 i
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.

§ 6. 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.,

ibicL 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.

§ 7. ESTIMATION OF ASH. 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 difficult 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, etc., 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, etc., 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.1

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 phosphoric and sulphuric acid and potash.
(See also § 82).

1 Compare also Borntrager, Zeitschr. f. anal. Chemie, B. xvii. p. 440 (1878).

8 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT.

II.

EXAMINATION OF THE SUBSTANCES SOLUBLE IN PETROLEUM

SPIRIT.

ETHEREAL AND FATTY OILS, WAX, ETC.

§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 I
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.
It 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 cc.
of the former. A small narrow cylinder with glass stopper may

§ 9. EXTRACTION. 9

be used for this purpose. It should be weighed immediately after
the introduction 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 aliquot part of the solution, and calculate
from the residue the weight of the substances which have been
brought into solution.1

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.2

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 accurate will be
the gravimetric estimation of the ethereal oil. If, however, the
petroleum-spirit solution is to be filtered off and the residue on

I 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 disbN,
with vertical sides and well-ground edges, a ground-glass ^1o^ -

acting as a cover. 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.)

1 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 rule, 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 0'91 to 0'925.

2 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.1 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 OIL.

§ 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

011 is seen in the form of small globules of high refracting power,
which dissolve in petroleum spirit, ether, and bisulphide of carbon,
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

1 For information concerning the so-called dietheralysis, see Legrip, Union
Pharrn. V. vi. p. 65 (1876).

§§ 11, 12. DETECTION, ETC., OF FIXED OIL. 11

quantity of water. " I do not think it improbable that in the juice
of fresh plants oil is held in solution by carbohydrates 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 total 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. J
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 difficult 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 solidification of the oil I
would prove the presence of oleic (§§ 19, 130) or an allied \ <U-
acid capable of conversion into elaidin (§ 122). In this case, on /
mixing the oil with about one-fifth of its volume of concentrated
sulphuric acid, but little heat will be evolved, whilst compounds
of the drying linokic 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 phosphoric acid.
The behaviour of the oil to syrupy chloride of antimony, nitric
acid (from J 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 calcium, 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, etc., 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 Glycerine. — It is well known
that natural fats are almost invariably 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 specific 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

§§ 14, 15. CETTL-, CEROTYL-, MELYL- ALCOHOL. 13

liquid. It is 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- y 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
difficult 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 hydrochloric 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 hydrochloric acid, and the fatty
acids separated from the aqueous liquid. The possible presence of
valerianic, caproic, caprylic, pelargonic, capric, and lauric (§ 130),
also angelic and methyl-crotonic 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.

§ 16. Less-volatile Fat- Acids. — If no volatile acids are present,
or after their separation by distillation, as directed in § 15, the
less volatile fat-acids may be dissolved in alcohol and subjected
in alcoholic 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 CnH2n02 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 precipitate shall weigh about
1 to 5 grams, and this is continued till the tolerably strongly am-
moniacal liquid yields no further precipitation on the addition of
alcoholic solution of acetate of magnesium. Each precipitate
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. (Of. §§130 to 131.)

§ 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 cylindrical 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

18. MELTING-POINTS OF FAT- AC IDS.

15

a small flame, so that the temperature rises about 1° every two
minutes. l

§ 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
occasions, or if the estimations show a difference of only 0-5°, the
conclusion may be drawn with tolerable safety that the precipitate
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 30 '0°; lauric, 43 -6°; myristic, 53 '8°; palmitic,
62-0°; stearic, 69 -2°; arachic, 75'7°.

Mixtures of two of these acids in certain proportions possess, as
the investigations of Heintz2 have shown, a lower melting-point
than either of the constituents. Heintz has also noticed that the
mixture, on solidifying, crystallizes in a characteristic form, or
remains amorphous, according to the proportion in which the two
constituents are present.

Mixture of

Stearic Acid.

Palmitic Acid.

Melts at

Solidifies at

Manner of Solidification.

100

0

69-2°

—

Crystalline scales.

90

10

67'2°

62-5°

» 5J

80

20

65-3°

60-3°

Delicate crystalline needles.

70

30

62-9°

59-3°

»> » »

60

40

60-3°

56-5°

Amorphous, lumpy.

50

50

56-6°

55-0°

Large crystalline lamellae.

40

60

56-3°

54-5°

» »> »

30

70

55-1°

54-0°

Amorphous, wavy, dull.

20

80

57-5°

53-8°

Very indistinct needles.

10

90

60-1°

54-5°

Fine crystalline needles.

0

100

62-0°

—

Crystalline scales-.

Mix

ture of

Palmitic Acid,

, Myristic Acid. »

100

0

62-0°

—

Crystalline scales.

90

10

601°

55-7°

» »

80

20

58-0°

53-5°

Scaly and 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. p. 152 ;
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) ;
cf. ibid. Ixxxiv. 226.

3 For particulars of the examination of a fat in which stearic, palmitic, and
myristic acids were found, see Greenish in Pharm. Journ. and Trans. [3], x. 909.

16 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT.

Mixture of
Palmitic Acid. Myristic Acid.

Melts at Solidifies at

Manner of Solidification.

70 30

54-9°

51 '3° Extremely fine needles.

60 40

51-5°

49 '5° Amorphous, lumpy.

50 50

47-8°

45*3° Large crystalline lamellae.

40 60

47-0°

43 '7° Indistinct lamellae.

30 70

46-2°

43-7°

20 80

49-5°

41 '3° Amorphous.

10 90

51-8°

45 '3° Long needles.

0 100

53-8°

Crystalline scales.

Mixture of

Myristic Acid. Laurie Acid.

100 0

53-8°

Crystalline scales.

90 10

51-8°

47-3°

80 20

49-6°

44'5° Very minute crystals.

70 30

46-7°

39-0°

60 40

43-0°

39'0° Amorphous.

50 50

37-4°

357° Large crystalline lamellae.

40 60

36-7°

33 '5° Amorphous.

30 70

35-1°

32-3° Amorphous, frond-like.

20 80

38-5°

33-0°

10 90

41-3°

36'0° Crystalline needles.

0 100

43-6°

Scaly crystals.

Mixture of

Stearic Acid. Myristic Acid.

Melts at

Manner of Solidification.

100 0

69-2°

Scaly crystals.

90 10

671°

Distinct crystalline scales.

80 20

65-0°

Rather less distinct crystalline scales.

70 30

62-8°

Still less distinct crystalline scales ;

no needles or lamellae.

60 40

59-8°

Scaly crystallization commences ; no

trace of needles or lamellae.

50 50

54-5°

Amorphous, opaque.

40 60

50-4°

Beautiful large crystalline lamellae.

30 70

48-2*

Crystalline lamellae.

20 80

47-8'

Indistinctly crystalline.

10 90

517°

Amorphous, opaque.

0 100

53-8°

Crystalline scales.

Mixture of
Palmitic 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. Laurie Acid.

100 0

90 10

80 20

62-0° Crystalline scales.

59'8" Still distinct crystalline scales.

57'4° Somewhat less distinct cryst. scales.

54'5° Still less distinct crystalline scales.

51'2° Granular, indistinct crystalline scalf

47'0° Almost amorphous, opaque.

40'1° Beautiful large crystalline lamellae.

38-3° Small crystalline lamellae.

37'1* Indistinctly crystalline.

41'5° Amorphous.

43-6° Crystalline scales.

69'2° Crystalline scales.

67 '0° Still distinct crystalline scales.

64*7* „ ,, ,,

§ 18. MELTING POINTS OF FAT ACIDS. 17

Mixture of

Stearic Acid. Laurie Acid. Melts at Manner of Solidification.

70 30 62-0" Distinctly granular and scaly.

60 40 59'0" Granular ; commencement of scaly

crystallization.

50 50 55'S" Almost amorphous, slightly granular.

40 60 50 '8° Amorphous, warty.

30 70 43'4a On the surface shining faces of small

crystals.

20 80 38'5° Amorphous, warty.

10 90 41-5° Amorphous.

0 100 43-6' 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
46-2°, 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 :

Manner of Solidification.
Amorphous.

Stearic Acid.

Melts at

1

45-2°

2

44-5°

3

44-0°

4

43-8°

5

44-6'

6

45-6'

7

46-0'

8

46-5'

To 20 parts of a mixture of 30 parts of myristic with 70 of lauric
acid, melting at 35*1°, palmitic acid was added, and the following
observations made :

Palmitic Acid. Melts at Manner of Solidification.

1 33-9' Amorphous.

2 33-1-

3 32-2-

4 327'

5 33T

6 34-6'

7 35-3°
36-0-

9 37 '3* Indistinct 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 conclusion to be
drawn is that the last is palmitic acid, and that the fractions with
lower melting-points consist of mixtures of stearic and palmitic
acids. According to Heintz's table a mixture of equal parts of
stearic and palmitic acid should melt at 56*6°, and assume on
cooling a lamellar crystalline structure. Should no palmitic acid
have been found, but in its stead a fat-acid melting at about 53°
to 54°, the presence of myristic acid is to be inferred and the
mixture melting at 56 '6° would contain about 55 parts of stearic
to 45 of myristic 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 stearic add 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 calcium salts
are soluble in boiling alcohol, but the major part separates out
again on cooling.

Palmitic 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. Okie Acid, etc. — The alcoholic liquid from § 16, which
gives no further precipitate 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, etc., 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 hydrochloric acid. The fat-acid which col-
lects on the surface of the liquid may be removed mechanically,

§§ 19, 20. CHLOROPHYLL. 19

or by agitation with ether. In examining these acids attention
must bo paid to the possible presence of members of the oleic-acid
series (§§ 130, 131) and of the allied ridnoleic 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 alcohol ; or by frac-
tionally precipitating an alcoholic solution of a soda-soap with
acetate of barium, or acetate or chloride of calcium (§§ 130, 131).

•CHLOROPHYLL AND ALKALOIDS EXTRACTED SIMULTANEOUSLY
WITH THE FIXED OIL.

§ 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
tupon its solubility by the fixed oil. That the green colour is
really due to chlorophyll may easily be shown by spectroscopic
-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)1 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

1 In examining a fresh leaf, only the most marked line between B and C i*
seen. Compare Vogel, Ber. d. d. chem. Ges. B. xi. pp. 623, 1367 (1878).

9 9

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-
metric) 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 hydrochloric acid.

§ 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 sulphuric
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

$ -2-2. DETECTION, ETC., OF 'ETHEREAL OILS. 21

must be treated as above described, and the alkaloid so isolated
added to the extracts in which vegetable bases are to be looked for.

EXAMINATION OF THE ETHEREAL OIL.

§ 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.

AVe have now to estimate the amount of ethereal oil present
.as accurately as possible, without using any very large quantity
of material. From experiments made by Osse1 the following
method would appear to be the best. A quantity of the
petroleum- spirit solution is accurately measured on to a carefully
tared glass dish, which can be closed air-tight. (Of. § 9.) If 5 cc.
•of the solution correspond to 1 gram of substance, 1 to 2 cc. will
he found to be sufficient. The glass dish containing the petroleum-
.spirit solution is then placed under a tubulated glass bell-jar

•(Fig. 1), A, 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 close below the cork, and con-
nected with an aspirator (B), so that a current of dry air may be

1 Archiv d. Pharm. [3], vii. 101 (1875) (Year-book Pharm. 1876, 362).

22 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT*

drawn through the apparatus, entering by the tube 5, and
passing out through a. A chloride of calcium tube (c) is placed
before 5, 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 A. 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 calcium tube (c) with a Wolff's bottle one-third full of
concentrated sulphuric 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-efficient of evapora-
tion,' multiplied by the number of minutes the dish has been
exposed. (Compare the examples of estimation in § 136.) If the
coefficient 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. In the 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

§§ 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, etc., that 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 the results. 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, etc., 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. — If 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 successive portions
of the aqueous distillate. The petroleum spirit is allowed to
evaporate 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).

§ 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 distinct acid
reaction, and contain formic, acetic, or other volatile acids of the
fat-acid series. In such a case the higher acids in the series
may be removed by shaking with ether or petroleum spirit. To

24 SUBSTANCES 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 (1'5). 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, etc.,
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 calcium may meet with success. Should that not
be the case, formic and acetic acids may finally be tested for (be-
haviour to mercuric chloride, ferric 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 formic acid
does, nor does it yield the iron reaction characteristic of acetic
acid, etc. ; the mercuric salt dissolves with difficulty in water1
(formic acid reduces mercuric to mercurous chloride).

§ 26. Salicylic, Benzole Add, etc. — It must also be borne in mind
that some of the acids of the aromatic series, such as salicylic and
ben zoic 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
d istillate with petroleum spirit small quantities of salicylic acid are
removed, but ether and chloroform may be more advantageously
employ ed ; the latter liquid is also adapted for the isolation o
benzole acid. On evaporating the ethereal or chloroformic (or
petroleum spirit) solution, both benzoic and salicylic acid are
obtained as crystalline residues difficultly soluble in cold water
(salicylic acid about 1 in 300). 2 The two acids may be dis-

1 Conf. Amer. Journal of Pharmacy, xxxviii. 9 (1866).

3 For particulars of the detection of salicylic acid in Viola tricolor 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] xii. 627.

§§ 26, 27. SALICYLIC, BENZOIC ACID, ETC. 25

tinguished by their behaviour to ferric chloride, with which
salicylic 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 ferric 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
{cinnamate of cinnamyl), or cinnamein (cinnamate of benzyl).
Both of these compounds are soluble in petroleum spirit, and are
resolved, by decomposition with an alkali, into cinnamic acid and
the respective alcohol Styracin crystallizes in needles, which,
according to Scharling,1 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., salicylic, benzoic
{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 principal 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 crystalline constituent be
deposited it should be separated and examined by itself. The
action of the oil on polarized light should be observed (§ 141), and
fluorescence looked for ; if present, it should be ascertained whether
warm water will remove a substance fluorescent either alone or on

1 Annalen d. Chemie u. Pharra. Ixviii. 168. See also Riigheimer Disserta-
tion, Tubingen, 1873 ; Kraut, Annalen der Chemie u. Pharm. clii. 129 (1S69) ;
<Amer. Journ. Pharm. xlii. 236) ; and Von Miiller, Ber. d. d. chem. Ges. Jg.
1876, 274.

26 SUBSTANCES SOLUBLE IN PETROLEUM SPIRIT.

the addition of caustic 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.
"VVestphal's specific-gravity balance may be advantageously em-
ployed for this purpose, especially if the quantity of oil at disposal
is rathey small. (Of. § 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 a change 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 sulphuric acid, alone or
applied in combination with sugar, nitre, or ferric chloride ; nitric
acid, alcoholic hydrochloric acid, solution of bromine in chloro-
form, picric 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 Sulphur. — Some ethereal oils contain sulphur,
which may be detected by mixing a few drops of the oil with
carbonate of soda and nitre, and introducing it into a piece of
combustion tubing, about 15 ctm. 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. 2T

heated with excess of hydrochloric acid as long as nitrous fumes
are evolved, and then tested for sulphuric acid by chloride of
barium.

Warming a small quantity of an ethereal oil containing sulphur
with a solution of caustic 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 nitrites. 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 ferric and ferrous salt, and, after a few
minutes, acidifying with hydrochloric acid, when a precipitate of
Prussian blue makes its appearance if nitrogen is present.

If the ethereal oil contains a sulphocyanide (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 principal
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 ojie
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 of 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 orderjgniake J:his modification available, the temperature
must first be ascertained at which the more commonly occurring
constituents of oils can be distilled. Many of the terpenes present
in ethereal oils may be distilled under the ordinary pressure at
lf>5° 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. § 143.)

§ 31. Stearoptenes, etc. — The following are the more important
constituents of ethereal oils that have up to the present time
been observed : Terpenes of the composition C10H16 often boiling
at 155° to 157°; polymers of the same, of the formula C15H24
and C20H32, boiling frequently at about 190° or about 250° ;
oxygenated compounds of the formula C10H200, C10H180, C10H160,
C10H140, C10H12O, C10H1202 ; hydrocarbons of the formula C10HM
are more rarely to be found ; still less frequently those of the
CnH2I1 series. Of these constituents of oils, it is noticeable that
those containing oxygen crystallize in the cold more readily than
hydrocarbons of the formula C10H16, and to the former, therefore,
our attention must be specially directed in the examination of
the crystalline ' stearoptenes ' obtained by cooling the oils (with
the exception of otto of roses = CnH2n).

/" If such a stearoptene has been isolated, its purification should
T be attempted by repeatedly crystallizing from alcohol or ether,
i pressing the crystals each time between blotting-paper. The co-
efficient of refraction may then be ascertained in the alcoholic
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 phosphoric anhydride or chloride
of zinc.

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 C15H24 and
C20H32, yield very characteristic colour reactions with the re-
agents detailed in §§ 28, 142 ; whilst oils consisting principally of
terpenes of the formula C10H1G show less inclination to give
marked reactions. These latter oils may often be purified for
ultimate analysis by distillation over metallic sodium.

§ 32. Other Constituents. — Besides the constituents already men-
tioned— which indeed, although frequently agreeing in their

§§ 33, 34, 35. ALDEHYDES, VOL. ACIDS, ETC. 21>

composition, have, when prepared from different plants, somewhat
dissimilar properties (odour, behaviour to polarized light, etc.) —
some ethereal oils contain other substances which may belong to
tolerably distant groups. Aldehydes, ethereal salts, alcohols,
acids, etc., have been found in various oils.

§ 33. Aldehydes. — If an aldehyde is to be looked for in an
ethereal oil, it must first be ascertained whether that oil precipitates,
metallic silver from an ammoniacal solution of the nitrate.1 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 liqui 1. 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 crystalline 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, salicylic, 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.2

§ 34. Volatile Adds. — 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 sulphuric acid. (Cf. §§ 25, 139.) Besides the volatile
acids already mentioned, the possible presence of hydrocyanic
acid, which is partially converted into formic 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 precipitate and sulphocyanide and Prussian-
blue tests.

§ 35. Ethereal Salts. — If an essential oil is to 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).

2 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 caustic 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.1
Acetate of octyl, which occurs in the oil of Heracleum, would
thus yield an acetate and octyl alcohol. Certain substitution
acids, such as methyl-salicylic acid, might be similarly decom-
posed; this, for instance, would yield a salicylate and methylic
alcohol. The latter class of compounds would split up on treat-
ment with hydriodic acid ; methyl-salicylic acid would thus yield
iodide of methyl and salicylic 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 hygroscopic substances may be often used with
success.2 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 alcohol 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°, octyl 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 sulphuric 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 alcohols
the reaction succeeds as far as amyl alcohol, in the series of primary
alcohols as far as octyl alcohol (Gutknecht).3

The acids separated from the ethereal salts, obtained by decom-
posing the alkali or barium salt with sulphuric or phosphoric 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

III.
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 (cf. § 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
through 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 calcium, and then rectify it after carefully separating the
calcium 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 with ether. 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 total
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 be 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.1

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.

§ 37. Chlorophyll. — The ethereal extract may also be tested
before evaporation for chlorophyll, as described in §§ 20, 132, et seq.
I have already observed that this substance is more easily and
completely removed by ether than by petroleum spirit.

§ 38. Portion Soluble in Water. — That part of the ethereal
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 hcematoxyKn*
gallic acid, catechin, pyrocatechin, salicylic acid, lenzoic acid,
1 Jahrb. f. Pharm. 1876, p. 369 (Year-book Pharm. 1876, p. 356).

§§ 39, 40. PORTION SOLUBLE IN ALCOHOL. 33

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 hsematoxylin and allied substances see § 150 ;
of gallic acid, etc., § 151 ; of salicylic and benzoic acid, §§ 26, 34;
of glucosides, §§ 54 et seq., 165 et seq. ; of alkaloids especially, §§63
.et seq., 171 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 alcoholic 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 microscopical 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 Miiller, is produced with resins by
alcoholic tincture 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 precipitating the concentrated ethereal
solution with alcohol, petroleum spirit, or other suitable liquid.
Similarly, if a substance soluble in ether has not from the tirst
been obtained in crystals, 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 crystallize the substance, or to
separate it into a crystalline and an amorphous portion.

If the endeavour^to obtain crystals be successful, the crystalline
form should if possible be determined, and care should be taken
to observe whether different crystalline forms can be distinguished
under the microscope, rendering it probable that the substance--
under examination is a mixture. l

§ 41. Behaviour of Eesins 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 alcoholic 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 the1
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, etc.,
and then an ultimate analysis made. It should be tested for
colour-reactioHS with concentrated sulphuric acid alone and in
conjunction with sugar. If ethereal solution of bromine yield &
substitution product, its composition should be ascertained. It
should also be noticed whether the resin-anhydride is easily
oxidized and dissolved by nitric acid, or whether that takes place-
only with difficulty j whether water precipitates the unchanged
resin after the action of the acid, or whether oxidation products
are formed ; and if so, what is their nature, as, for instance, picric2
or oxalic acid (§§ 81, 219), succinic acid (§ 220).

§ 42. Action of Fused Potash. — It is further important to become
acquainted with the products formed under the influence of fused
caustic potash or soda.3 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 crystals belonging to the rhombic system sparingly soluble in
cold water, more freely in boiling, soluble in alcohol and ether. It stains skin
and wool yellow, and yields a blood-red liquid when an alkaline solution is
warmed with cyanide of potassium, sulphide of potassium, or grape sugar.

3 Cf. Hlasiwetz and Earth, Annalen der Chemie und Pharm. cxxxiv. 265 'r
cxxxviii. 61 : cxxxix. 77.

§ 42. RBSOBGIN, PHLOROGLUCIN, ETC. 35

titles 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 crucible are dissolved in water, and a slight excess of
sulphuric or hydrochloric acid added. The decomposition pro-
ducts, which are specially to be looked for, are butyric and
valerianic acid (cf. §§ 25, 34, 139), pyrogallol, phloroglucin,
and resorcin, 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.

Resordn. — After the fatty acids have been removed by petroleum
spirit, resorcin may be extracted from the aqueous liquid by
shaking with ether and distilling the ethereal solution after sepa-
ration. It forms crystals melting at 99°, has a sweetish taste, and
strikes a dark violet colour with solution of ferric chloride, violet
with chloride of lime, and rose-red with ammonia. It reduces
ammoniacal solution of nitrate of silver.

Phloroglucin is also very sweektasted, and resembles resorcin in
many of its reactions, but is coloured reddish-violet with ferric
chloride, and transient reddish-yellow with solution of chlorinated
lime. The anhydrous crystals melt at 220°.

'Pyrogallol tastes bitter, is soluble in water, alcohol, and ether,
melts at 115°, reduces ferric 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.

Protocatechuic Acid has an acid reaction, is sparingly soluble in
water, strikes no colour with pure ferrous, but yields a dark-green
solution with pure ferric salts. With mixtures of both ferric 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 hydrochloric 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 difficulty in
cold water, and gives, with ferric chloride, a yellow precipitate
easily soluble in excess.

For Orcin and Betaorcin see § 158.1

§ 43. Dry Distillation of Resins. — It has already been mentioned
in § 27 that the dry distillation of part of the resin may lead to
useful results. Besides the umbelliferone mentioned in that
section, pyrocatechin (§ 151), pyrogallol, etc., 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-ferric 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 pcconiofluorescin
from peony-seed (§ 147). Chrysophanic acid and allied substances
(§§ 148, 149) should also be tested for, as well as quercitrin,
quercetin (§ 152), and the bodies discussed in §§ 150 to 158.

§ 45. 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 hydrochloric
acid, instantly decomposed with reproduction of insoluble anhy-
dride. In the case of santonin, santonic acid is liberated on
acidulating the alkaline aqueous solution. Any ordinary acid
resin mixed with it may be removed by precipitation with hydro-
chloric 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 EXTRACTION 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, etc. 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. It is then incinerated, and the ash deducted froi
the weight of the dry substance. After having thus estimated
the total organic matter insoluble in petroleum spirit and ether,
but soluble in alcohol, the residue on the filter may be wash*
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 di sh, and allowed to eva-
porate, at the ordinary temperature, over sulphuric acid.

§48. 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.

The remainder of the aqueous extract is reserved for the
experiments detailed in §§ 49, 50, 70 ; that which is insoluble ii

§§ 48, 49, 50. DETECTION OF TANNIN. 30

•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 §§ 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 subjected to similar treat-
ment as the resin soluble in ether (cf. §§ 39 to 45 ; 145, 146). If
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 §§ 55, et seq.; 63, et seq. ; 171, et seg?.)

EXAMINATION OF THE TANNIN.

§ 49. Detection. — If the aqueous solution obtained from the
evaporation residue of the alcoholic extract is coloured blue-black
by a ferroso-ferric salt and precipitated by gelatine, solution of
acetate of lead is to be added in slight excess. The resulting pre-
cipitate 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 (§ 52, I.). 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 precipitate, and the re-
mainder noted as tannic acid, or bitter principle precipitated by
oxide of lead, or vegetable acids precipitated by lead (§ 80). The
filtrate from the lead precipitate 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, II.). Here,
too, the amount of oxide of copper in the precipitate is to be
determined by following the same directions and deducted from
the weight of the precipitate. If the estimation with the copper
salt yields the same result as that with the lead, it is tolerably
certain that only tannic acid has been precipitated. But if lead
throws down more matter than copper we are generally justified
in assuming that the former precipitates substances other than

40 SUBSTANCES SOLUBLE IN ALCOHOL.

tannin, such as other acids, or bitter principles, the amount of
which may be approximately determined by deducting the weight
of the organic matter contained in the copper precipitate from
that contained in the lead. Under these circumstances the weight
of the organic substances precipitated by copper sometimes re-
presents approximately the tannin contained in the material
(§§ 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. Reactions. — The following reactions are common to all
tannins : they are precipitated 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-ferric 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. Cells 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 et seq.)
makes it exceedingly difficult to give any general rules for their
estimation. Some of my pupils1 have therefore at my instance
tasted 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 resum6 of the results they hav(
obtained I should like to observe that, in my opinion, the esti
tion of the tannin in the alcoholic extract, prepared as I hav(
described, is preferable to the determination in the aqueous ex-
tract, provided of course that the material is very finely powder*
that the tannin is insoluble in ether free from alcohol, and that tl
alcoholic liquid has been evaporated under diminished pressure

1 Compare Giinther, Pharm. Zeitschr. f. Kussland, Jg. 1870, pp. 161, 193,
225, and ' Beitrage zur Kenntniss der in Sumach, Myrobalanen etc. vorkom-
menden Gerbsauren,' Diss. Dorpat, 1871, and other Dorpat dissertations sub-
sequently referred to.

§§ 51, 52. ESTIMATION OF TANNIN. 41

and dried as directed in § 47. One advantage in employing
alcohol to extract the tannin, as already recommended by Loewe,
is the exclusion 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. — Pribram1 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-tannic 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.
Some of the precipitates (tannic acids from oak- and willow-bark)
are decomposed by prolonged washing with water, the tannic acid
partly passing into solution and undergoing change. It was for
these reasons that I have recommended the precipitation 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-

1 Zeitschr. f. anal. Chemie, v. 455 (1866). Compare also Jacobson, Chem.
techn. Report. 1866, ii. 85 ; Stein, Schweiz. polyt. Zeitschr. ii. 169 ; Gietl,
Zeitschr. f. anal. Chemie, xi. 144 (1872) ; and Schmidt, Zeitschr. d. osterr.
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-tannic acid at times also yields
good results.

II. Acetate of Copper has been suggested by Sackur1 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 precipitate
in tolerably concentrated solutions, not to wash too long, and to
•estimate the tannin gravimetrically, as above described.

III. Stannous Chloride and Ammoniacal Stannous Chloride, which
have been recommended by Risler-Beunat2 and Persoz,3 for the
estimation of tannin, precipitate 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 precipitate 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 precipitates 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 Gerland4
and Roller5 for the volumetric estimation of tannin, will yield

1 Gerberzeitung, xxxi. 32. See also Wolff, Krit. Blatter f. Forst und
Jagdwissensch. xliv. 167 ; Fleck, Wagner's Jahresber. f. techn. Chem. Jg.
1860, p. 531 ; Hallwachs, Zeitschr. f. anal. Chem. v. 234 (1866).

2 Zeitschr. f. anal. Chem. ii. 287 (1863).

3 Traite de 1'Impression des Tissus, i. 282. The results obtained by
method recommended by Persoz, in which the amount of tannin is calculated
from the volume of the precipitate, are, according to Gauhe (Zeitschr. f. anal.
Chem. iii. 130, 1864) and Cech (Stud, iiber quant. Best, der Gerbsauren, 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 re vie w of the more important methods of
estimating tannic acid. (See Procter, Pharm. Journ. Trans. [3], vii. 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-j
(X. Jahrb. f. Pharm. xxv. 206, 1866).

§ 52. ESTIMATION OF TANNIN. 43

•satisfactory results in some few cases only, because, even if the
solution be mixed with chloride of ammonium, it is difficult to
ascertain when a sufficient quantity of the reagent has been
Added, and because some of the tannin precipitates so produced
are rapidly decomposed. Some tannins (rheo-tannic acid) are not
precipitated at all by tartar emetic.

V. Ammoniacal Solution of Acetate of Zinc. — This reagent
should, according to Terreil,1 Carpene",2 and Barbieri,3 be used
in the following manner for the estimation of tannic acid. The
liquid to be precipitated is brought to the boiling-point, an excess
of the zinc solution added, and, after concentration by evapora-
tion, the mixture is cooled and filtered. The precipitate is then
dissolved in sulphuric acid, and the tannin estimated by titration
with permanganate of potassium. I must admit that some tannic
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 4 for the estimation of tannic 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 precipitate contained 45 -8 per cent, of oxide of iron that
the estimation yielded satisfactory results.

Still less feasible is Wildenstein's5 colorimetric examination,
which is based upon the intensity of the colour produced by the
solution on paper impregnated with ferric citrate.

VII. Titration with Permanganate of Potassium.. — Monier,6 Cech,7

1 Zeitschr. f. anal. Chem. xiii. 243 (1874).

2 Ibid. xv. 112 (1876).

3 Ibid. xvi. 123 (1877). See also Kathreiner, ibid, xviii. 113 (1879).

4 Jovirn. f. pr. Chem. Ixxxi. 345.

5 Zeitschr. f. anal. Chemie, ii. 137 (1863).

6 Compt. rend. xlvi. 447. 7 Loc. tit.

44 SUBSTANCES SOLUBLE IN ALCOHOL.

Lowenthal,1 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. Lowenthal 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 Giinther ascertained that
16 parts of oxygen from the permanganate oxidized 32-5 parts
of gallo-tannic acid, 33'0 of sumach-tannic acid, 25-0 (5-54) of
catechu-tannic acid, 24-0 (5-32) of catechuic acid,2 28'0 of kino-
tannic acid, 34 to 37 of rhatania-tannic acid, 35 of tormentilla-
tannic acid, 34 of caffeo-tannic acid, and 32 of oak-bark-tannic acid.
Neugebauer3 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 tannic 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 animal charcoal were foreign bodies. Lowenthal (see
below) titrates a part of the tannin solution direct, another part
after precipitation with solution of gelatine (XII). From the differ-
ence in the quantity of permanganate used the tannin is calculated.

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).

§ 52. ESTIMATION OF TANNIN. 45

If a solution contain both gallic and tannic acid, or catechin
and catechu-tannic acid, both may be approximately estimated
by Lowenthal's method. (See also § 164, et seq.) The addition
of gelatine as directed by him introduces only a slight source of
error, which may be generally neglected.

VIII. Chlorinated Lime. — Lowenthal1 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.

Cech2 has already expressed an unfavourable opinion of the
propositions of Commaille3 and Millon4 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 tannic acid in the presence of carbonate of soda has
been recommended by Jean5 for the quantitative estimation of
tannin. He states that 1 part of gallo-tannic 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
gallic 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
tannic acid for standardizing should contain 1 part in 1,000 of
water. Before titrating, 2 cc. of a 25 per cent, solution of cryst.
carbonate of soda should be added for every 10 cc. of tannic acid
solution. It must be observed that here, too, many organic com-
pounds would act in a similar manner to tannin.

IX. Oxidation. — For the estimation of tannin Mittenzwey6 has
availed himself of the fact that an alkaline solution of tannic 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 icith Cinchonine. — Wagner 7 has proposed titration
with sulphate of cinchonine, using acetate of rosaniline as an

1 Loc. cit. 2 Loc. cit. 3 Compt. rend. lix. 599 (1864).

4 Annales de Chimie et de Phys. [3], xii. 26.
' Zeitschr. f. anal. Chem. xvi. 123 (1877).

6 Journ. f. pr. Chemie, xci. 81, and Zeitschr. f. anal. Chemie, iii. 484 (1864).
3 also Terrell, Zeitschrift des osterr. Apothekervereins, Jg. xii. 377 (1874).

7 Zeitschr. f. anal. Chem. v. 1 (1866). See also 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 cinchonine, 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 precipitated. In many
cases better results might be obtained with cinchonine if the
tannic acid were precipitated 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 tannic 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. Hammer1 has constructed a
table for gallo-tannic acid, from which the amount 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.

XII. Gelatine : Gravimetric Process. — Precipitation of the tannin
by gelatine, and calculation of the amount present from the weight
of the precipitate, has also been tried. But the disadvantages
which present themselves here are that these precipitates 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 tannic acid are removed.

It is, therefore, most advantageous to apply the precipitation

1 Journ. f. pract. Chem. clxxxi. 159. See also Lowe, Zeitschr. f. anal.
Chem. iv. 365 (1865), and Hallwachs and Cech (foe. cit.}. Davy has already
estimated tannic acid gravimetrically by employing hide (Chem. News, 1863*
p. 54, and Zeitschr. f. anal. Chem. ii. 419).

§§ 52, 53. GALLIC AND CATECHUIC ACIDS. 47

with gelatine in the following manner : A solution of that sub-
stance— the 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 mixed with some salt,
diminishing the solubility of the tannate of gelatine. For the
latter purpose the addition of alum has been recommended
(Miiller1). The proposal of Schulze2 to use chloride of ammonium,
or of Lowenthal to add common salt and -^ vol. of hydrochloric
acid (specific gravity 1*12), appears better. 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 Lowenthal'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 Giinther that the various tannins
differ in the amount of gelatine they are capable of precipitating.
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-tannic acid. As is well-known, gallic and catechuic
acids do not precipitate gelatine.

§ 53. Gallic and Catechuic Acids. — If one of these two substances
is to be looked for, the tannic acids should be first precipitated 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. cit.}.

• 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
critical review of the more important methods for estimating tannic acid by
Lowenthal will be found in the Zeitschr. f. anal. Cfremie, 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 gallic
-catechuic acids remain behind in a crystalline form, generally
needles felted together. (Cf. §§ 151, 165.)

The weight of the dried residue frequently indicates wit
tolerable accuracy the quantity of the substance present ; but i]
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 permanganat
of potash. (See above.) If the material has been extracted wit
ether previous to treating with alcohol, gallic and catechuic acids
will be found in the aqueous solution from the ethereal extract
<Cf. §§ 38, 151.)

For the free vegetable acids which may occur in the alcoholi<
-extract see § 82. (See also in § 159.)

EXAMINATION FOR GLUCOSIDES, BITTER PRINCIPLES,
ALKALOIDS, ETC.

§ 54. Extraction ly Agitation. — If no tannic acid or allied sul
.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
suspected, the watery solution prepared from the evaporatioi
residue of the alcoholic tincture may be subjected to consecutive
treatment with various liquids which, being themselves insolul
in water, are adapted for removal of substances in solution b}
agitation and separation. The aqueous solution from the etheres
extract (§ 38) may also be treated in a similar manner. The use oi
petroleum spirit, benzene, and chloroform may be especially recom-
mended for this purpose ; they should be employed in the orde
in which they are named, and the liquid should be rendered fii
slightly acid with sulphuric acid, and subsequently alkaline wil
ammonia; I have spoken at length on this subject in my 'Erinit
telung der Gifte.'1 After each agitation, the solvent should
separated, washed once by shaking with pure water, agaii
separated, evaporated to dryness, and the residue examined. If
solvent, as for instance petroleum spirit, removes any appreciable
quantity of a substance, the agitation with this liquid should

1 P. 119. Compare also Russ. Archiv flirgerichtl. Med. J. i. und Phan
Zeitschr. f. Kussland, 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 mtro-benzene when treated with fuming nitric 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 :

Salicylic acid (cf. § 26). Pungent principles of capsicum, etc.
{§ 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 §§ 171, 178). Absyntliini cannot be
completely removed by petroleum spirit (§ 156). Hop-resin
(§156).

Benzene removes from the same solution santonin (cf. § 154);
caryophyllin (§ 156) ; cubebin (§ 155) ; digitalin (remains principally
in that part of the ethereal extract which is insoluble in water
(cf. § 155) ; cjratiolin (§ 167) ; cascarillin (§ 156) ; elaterin (§ 156) ;
populin (§ 167); colocyntliin (§ 167); absynthin (§ 156); quassin
(§ 156); menyanthin (§ 167); ericolin (§ 155); daphnin (§ 167);
Utter principle of Cnicus benedictus (§ 168); caffeine (§§ 171, 176);
piper'm (see above); colckiceme (§ 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
others : Betizoic acid (cf. § 26) ; digitalein (sparingly soluble in
ether, § 155); convallamarin (§ 167); saponin (insoluble in ether,
difficultly soluble in absolute alcohol, § 77 et seq., 167); senegin
(the B&me) ; physalin (§ 167); syringin (§ 167); cesculin (§ 167);
jiicrotoxin (§ 155); helleborein (§ 167); cinchonine (is insoluble
in ether, §§ 171, 182, 184); theobromine (§ 177); papavervne
($ 171); narceine (§ 171). Colchicine, solanidlne, quebrachine,
(jeissospermine.

§ 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 renderii
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 moi'phine, solan inc,
(§ 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 strychnine, Irucine, 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-
tine, lobeliine, sparteine, alkaloids in pimento, capsicum and
Sarracenia purpurea. Aniline, trimethylamine, and allied sub-
stances are also dissolved by it (§§ 171, 239). In 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 hydrochloric acid, on which the hydro-
chlorides of the alkaloids will partly, at all events, remain
behind. A freshly-prepared dilute solution of hydrochloric 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, qiiinidine, 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, nupharine, the alkaloids of
celandine, and small quantities of morphine (§ 171).

§ 57. Direct Tests for Glucosides, Alkaloids, etc. — The number of
acids, glucosides and alkaloids (cf. § 21) that may be isolated by

§§ 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 principles and gluco-
sides are to be looked for. Alkaloids may likewise be tested for
by digesting the material with water acidulated with sulphuric
acid (1 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), precipitating with about three volumes of spirit,
filtering after standing twelve to twenty-four hours in a cold place,
and distilling off the alcohol.

§ 58. Alkaloids, etc., not Removable ly 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 convolvulaceaB. Such substances are generally isolated with
the resins. (Cf. § 153.)

The purification of bitter principles 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 alcoholic 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.

purify a bitter principle dissolved by water from the ethereal ext
than one obtained in a similar manner from the alcoholic 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 principles, etc., may frequently be
removed by digesting the aqueous infusion with oxide or hydrate
of lead. If salicine (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 of lead 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 sep
tion may sometimes be effected from sugar, etc. This method i
however, inapplicable if tannic acid be present, when it will o:
be found advisable to precipitate vegetable acids, tannin, etc.,
neutral acetate of lead before throwing down the bitter principl
etc., with the basic salt (§§ 51, 162).

§ 60. Separation of Lead Precipitate. — If such compounds of 1
with bitter principles, glucosides, etc., are to be washed wi
water, it is very advisable to effect this as rapidly as possible
decantation. Such precipitates often block a filter, or form,
contraction, channels through which the wash- water runs off wi
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 precipitates is
usually effected by sulphuretted hydrogen, which, however, does

§§ 60, 61. GLUCOSIDES; RECOGNITION. 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 principle 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 alcoholic extract care should be taken not to
confound crystals of sulphur with the bitter principle, etc. It
will often be found advantageous to decompose the lead precipi-
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.)

§ 61. 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 circumstances,
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 hydrochloric 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. §§ 153, 160.)

The decomposition-products 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-product 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 the 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 sulphuric 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 circum-
stances, carbonic-acid gas is evolved. Many glucosides yield,
besides glucose, products of decomposition which are antagonistic
to alcoholic 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 excluded, 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, not glucose, but substances allied
to sugar or mannite, which, like isodulcite, are unfermentable.
(Cf. § 212.)

§ 62. Sulphuric Acid Group-reaction. — Many glucosides are capable
of acting like sugar when mixed with bile and sulphuric acid—
that is, of producing a red colour. This reaction has been described
as to a certain extent characteristic 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,
et seq.

§§ 63. ISOLATION OF ALKALOIDS, ETC. 55

§ 63. Isolation of Alkaloids, etc., 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 extracts prepared according
to § 57 should be exhausted as far as possible by shaking with
petroleum spirit, etc., 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 that end the liquid obtained in § 57, containing
sulphuric acid but no alcohol, may be tested for alkaloids by
precipitants 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-
inineral 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 precipitate is formed, it differs
in properties from that produced in aqueous solutions. For
example, berberine and narceine would under these conditions
yield crystalline precipitates.

Tribromide of potassium, prepared in a similar manner, also pre-
cipitates some of the alkaloids from very dilute solutions, but, in
addition, forms yellowish compounds with phenol, orcin, and
many allied bodies (§ 158).

Potassio-mer curie iodide, obtained by decomposing mercuric
chloride with an excess of iodide of potassium, yields with
most alkaloids, white, flocculent precipitates, which sometimes
gradually assume a crystalline character. (See also § 65.) The
presence of free acid may sometimes cause a difference in the
precipitate obtained from one and the same alkaloid.

Potassio-bismuthic iodide, prepared by dissolving iodide of bis-
muth and iodide of potassium in water, yields, even in highly
dilute solutions, precipitates 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.)

Potassw-cadmic iodide, obtained in analogous manner from iodide
of cadmium, gives white precipitates, 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-molyldic acid (a solution of the sodium salt in nitric
acid) yields with most alkaloids yellowish precipitates, 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 precipitates with
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, etc. The precipitates obtained with this reagent also some-
times show a disposition to decompose.

Mercuric chloride. — The white precipitates which this salt yields
with alkaloids are not very sparingly soluble, but it possesses
some value, as it does not precipitate ammoniacal salts, etc. The
same is the case with

Picric acid, which gives yellowish precipitates.

Tannic acid, the compounds with which are usually of a greyish-
yellow or greyish-brown tint, and

Bichromate of potasli, which yields yellowish and occasionally
crystalline salts.1

1 For group-reagents for alkaloids see further in iny 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, etc.). This test will be specially valuable if another
peculiarity of most, but not all, alkaloids— viz., the alkaline
reaction towards litmus and capability of forming salts — be not
well defined (colchicine), or if a compound be obtained which
must be referred to the group of amido-acids (colchicine) 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.

§ 64. Alkaloids not Isolated by the MetJiod 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 precipitated by
potassio-mercuric iodide from its solution in water acidulated with
dilute sulphuric acid, the precipitate filtered off, washed, sus-
pended in water and decomposed by sulphuretted hydrogen. On
filtering off the sulphide of mercury, a solution of the hydriodate
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 off. 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 sulphuric acid by carbonate
instead of hydrate of barium. The former, moreover, would be
less likely to decompose 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,

clxxiv. 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
difficult to remove, and clear liquids can only be obtained by
repeated filtration through double niters.

Should the alkaloid, after liberation with caustic baryta, be
sparingly soluble in water, it may be precipitated simultaneously
with the sulphate of barium. 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 circumstances yields tropine and tropic acid ; hyoscyamine
is resolved into the same two substances. (Cf. § 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 ; lycoctonine = pseud-
aconine).1 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-molyldic or phos-
pho-tungstic add (§ 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.2

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 Wasowicz, Archiv
d. Pharm. xiv. 193 (1879) (Pharm. Journ. and Trans. [3], x. 310). See papers
by Wright and Luff, etc., 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, Giinther has successfully em-

§ 65. ESTIMATION OF ALKALOIDS. 59

3. The alkaloid may -be precipitated from its aqueous solution
"by certain reagents, and estimated gravimetrically.

Chloride of gold, or sometimes perchloride of platinum (§ 173),
may be advantageously used as precipitant in the last case, as the
amount of alkaloid and chlorine present may be approximately
calculated from the amount of gold or platinum contained in the
precipitate. Alkaloids may often be estimated gravimetrically
and volumetrically by precipitation with potassio-mercuric iodide
(§ 174).

I have discussed this subject fully in my ' Chemische Werth-
bestimmung starkwirkender Droguen,'1 where I have shown that
many alkaloids may thus be accurately estimated. I found, how-
ever, that the precipitates 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 sulphuric 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
precipitation, 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 precipitant. 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. Kussland, 1869, p. 89 (Year-book Pharm. 1872, 236). In
colchicum 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.

1 St. Petersburg, 1874. Schmitzdorff.

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 mucilaginoi
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 cc. of potassio-mercuric 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^Lj + Hgl^1 In the latter case
a correction of 0 '00005 gram of aconitine must be made for every
cc. of solution.

1 cc. of potassio-mercuric iodide indicates 0*0388 gram nepaline
(pseudaconitine).

Atropine. — 1 cc. 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
(C17H24N03I)2 4- HgI2. In working with solutions containing
1 in about 350 to 500 a correction must be made of 0-00005 gram
of atropine for every cc. of filtrate (§ 174).

Hyoscyamine. — 1 cc. of the mercury solution is equivalent to
0*00698 gram hyoscyamine, the concentration being about 1 in
200. According to the more recent researches of Ladenburg
henbane contains two alkaloids, one of which is isomeric with
atropine, and identical with daturine and duboisine. Compare
Berichte d. d. chem. Ges. xiii. 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.2
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 volumetric determinations.

2 Compare Kraut, Ber. d. d. chem. Ges. xiii. 165.

§ 65. ESTIMATION OF ALKALOIDS. 61

the hyoscine of Hdhn and others. Its gold salt melts at a higher
temperature than that of atropine or hyoscyamine.] (See further
in § 174.)

Ernriine. — 1 cc. of the potassio-mercuric iodide precipitates
0*0189 gram emetine. The precipitate has the composition

Coniine. — 1 cc. indicates 0*0125 gram, coniine provided that the
solution contain J 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 (C18H16NI)2 + HgI2 (§§ 174, 180).

Nicotine. — 1 cc. indicates 0 '00405 gram nicotine; the composi-
tion of the precipitate is C10H16N2I2 + HgI2.

Strychnine and Brucine. — 1 cc. precipitates 0'0167 gram strych-
nine and 0-0197 granf anhydrous brucine (in the latter case
as little free acid as possible should be present). The pre-
cipitates have the composition C21H29N202HI + HgI2, and
C23H26N204HI + HgI2(§§ 174, 180).

Colchicine. — 1 cc. precipitates 0-0317 gram colchicine, the con-
centration being about 1 to 600, and the solution containing 7 to 10
per cent, of sulphuric acid. The precipitate appears to contain
four equivalents of colchicine to one of HgI2.

Morphine and Narcotine. — 1 cc. corresponds to 0'02 gram crys-
tallized morphine2 and 0'0213 gram narcotine. (See also § 174.)

Veratrine, sabadilline, and sabatrine. — 1 cc. indicates, according
to Masing,s 0-0296 gram veratrine. Little sulphuric acid only
should be present and a correction of 0*000068 gram veratrine
made for every cc. of liquid. According to the same chemist,
1 cc. of the potassio-mercuric iodide is equivalent to 0-0374 gram
sabadilline and 0*03327 gram sabatrine. Correction for every cc.
0-00005 gram of the former and 0-0000408 gram of the latter
(§ 174).

Physostlgmme. — 1 cc. precipitates 0*01375 gram physostigmine
(Masing). Correction for every cc. 0*000105 gram. The com-
position of the precipitate is assumed to be C15H21N302HI + Hgl.,.
(See also § 174.)

1 This formula, also, will have to be altered as soon as analyses of the pure
emetine prepared by Podwissotzki are published.

2 For the 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).1
The precipitate is stated to contain almost exactly half its weight
of pure berberine.

Quinine. — According to Prescott2 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 Hielbiga
it would appear that no special advantage is to be looked for in
the application of potassio-mercuric iodide to the quantitative
estimation of quinine.

Chelidonine and Sanguinarine. — From some experiments made by
Masing I anticipate that 1 cc. of potassio.-mercuric iodide will be
found to indicate 0 '01 6 75 gram of the former and 0 '01 48 5 gram
of the latter.4 (Compare also § 174 et seq.)

§ 66. Estimation ofTheine, 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,5
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.6 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 cinchona-bark, but the long-continued action
of the dilute acid necessary to dissolve the alkaloid appears to
decompose part of it and renders the estimation inaccurate. (Com-
pare § 176.)

§ 67. Extraction of Cinchona Alkaloids. — In a series of experi-
ments in my laboratory the following method was found by
Hielbig7 to be the most advantageous : 25 grams of powdered
bark are digested with 100 grams of 1 per cent, sulphuric 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, etc. Diss. Dorpat.

4 Compare my Chemische Werthbestimmung, p. 101. Also Naschold,
Journal f. prakt. Chem. cvi. 385.

6 Compare Cazeneuve, Jahresb. f. Pharm. 1875, 342.

6 Compare also Losch, 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

elude 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 fcr
half an hour on the water-bath. To the filtrate, together with
100 cc. of wash-alcohol, 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 sulphuric acid
(1 to 7) or more if much cinchonine 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 cc.); 15 cc. of
2 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 cc. 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
§§ 183, 184.

§ 68. Estimation lij Titration. — If 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 ~$ acid. A method of this kind has
been proposed by Schlossing and others for the quantitative
determination of nicotine in tobacco.1 (See §§ 179, 180.)

§ 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 cinchonine, narcotine from morphine, delphinine from
delphinoidine.

1 Annales de Chim. et de Phys. xix. 230 (Am. J. Pharm. xix. 68) ; also
' Wittstein and Brandt, Vierteljahresschrift f. prak. Pharm. xi. 351, and xiii.
322 ; Liecke, Zeitschr. f. anal. Chem. 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, etc.,
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, etc. 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 §§ 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 aqueous 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 cupric 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 hydrochloric 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).

71, 72. TREATMENT WITH WATER, ETC. 65

Y.

EXAMINATION OF SUBSTANCES 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, sulphuric, or phosphoric
acid, chlorine, lime, magnesia or potash ; and if large quantities of
sulphuric 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 Serrurier1 advises the addi-
tion of J per cent, of alcohol before evaporation. It is claimed
that the residue is then porous and easily dried.

EXAMINATION OF MUCILAGINOUS SUBSTANCES, DEXTRIN AND
ALLIED CARBOHYDRATES PRECIPITATED BY ALCOHOL.

§ 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. Bpth filter and sub-
stance are then incinerated and the ash weighed, that of the filter
being deducted. If the precipitate 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 precipitate 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 hydrochloric acid. Its concentrated
solution is precipitated by basic acetate of lead. It is also
occasionally precipitated by ferric 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
precipitate 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 §§ 92 d seq.; 95 et 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, etc. If, on treating the mucilage
precipitate with a little water, a difficultly soluble crystalline 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.

§ 75. Inulin. — If subterranean parts of plants belonging to
Compositae or allied orders are under examination, they may,
even though previously dried, yield a little inulin to water.
After precipitation with alcohol it is not redissolved by water at
the ordinary temperature, but is freely soluble when warmed
to 56°. It is laevo-rotatory, is'converted by treatment with dilute
acid into levulose, and may be^estimated by determining the

§§ 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 triticin, 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 precipitated 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 triticin yield levu-
lose. The first of these three is optically inactive ; sinistrin and
triticin are laevo-rotatory (aD = — 32*456° and — 43*579° respec>-
tively). None of the four are coloured either blue or red by
iodine.1 Sinistrin and triticin are precipitated by caustic baryta,
from solution in 40 per cent, alcohol. Carbonic acid liberates the
carbohydrate from the~compound thus produced (§ 198).

Quantitative Estimation (§§ 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-precipi-
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. — If the precipitate obtained with
alcohol in § 76 is rapidly filtered off, the majority of the saponin

1 It 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.

5—2

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 carbonic 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, etc. 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,
(Of. § 55.) The residue, moistened with a few drops of concen-
trated sulphuric 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. — Christophsohn1 and Otten2 have
adopted the following two methods for the determination of
saponin :

^.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, precipitated 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. liber das Saponin, etc.' Diss. Dorpat, 1874, and Archiv
d. Pharm. vi. 432, 481.

2 Histiol. Unters. der Sarsaparillen. Diss. Dorpat, 1876.

§§ 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 hydrochloric 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 alcoholic 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 3 5' 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) ... ... 8'67 8 • 82 % Saponin.

2. Gypsophila struthium (root) ... 14*59 15*0 „ „

3. „ ,, ,, ... 13-31 13'2 „

4. Saponaria officinalis (root) ... ... 478 5 '09 „ „ *

5. Agrostemma githago (ripe seeds) ... 6'67 6*51 „ „

In the various sarsaparillas Otten found, by method A, from
1*21 to 3 '43 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 hydrochloric acid. Like saponin, it is easily
soluble in cold water, sparingly in cold absolute alcohol. (Of.
& 155, 1&7.)

EXAMINATION FOR ACIDS, ETC.

§ 80. Estimation of Total Organic Acids. — Part of the filtrate
obtained in §§ 73 and 76 is concentrated and, after complete
dissipation of the alcohol, precipitated with neutral acetate of lead,
avoiding an 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
substances. 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 nitrate from § 73 or
§ 76, by precipitation with acetate of copper (cf. § 50), and de-
ducted from the total organic acids.

§ 81. Qualitative Separation. — If the lead precipitate is at first
amorphous, but becomes crystalline on standing, malic or fumaric
acid1 may be present. (See also §§ 214, 220, 221.)

The acids thus precipitated may be further qualitatively examined
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.2 (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. Tartrate of calcium
(§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 boiled. Any turbidity that may now occur would
indicate citric acid. (§§ 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 sulphuric 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 probable that the so-called Marattin is aconi-
tate of calcium (§ 102). Sphaero-crystals of this substance were

1 For the solubility of malate of lead in warm dilute acetic acid, and the
deposition of a crystalline 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 nitration passes
through the pores of the filter. Muck has shown (Zeitschr. f. anal. Chemie,
ix. 451) that the precipitate is much easier to manipulate if small quantities of
aluminium salts are present.

§§ 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 tartaric,
citric, racemic acid, etc. Citric acid may be detected by boiling
the filtrate. Citric and tartaric acids may be separated quantita-
tively by Allen's method.1 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 el seq ; 217 etseq.)

§ 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 precipitate 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 alcoholic solution of methyl-violet. Mineral acids change
the colour to bluish-green.

The amount of free acid present in fruits, etc., 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 calcium and potassium), the liquid may be evaporated to a
syrupy consistence and the tartaric acid extracted with ether or
absolute alcohol.2 The alcoholic or ethereal solution is evapo-
rated, the residue dissolved in a little spirit and the tartaric acid
separated by the addition of alcoholic solution of acetate of
potassium.3

1 Zeitschr. f. anal. Chemie, xvi. 251 (Pharm. Journ. Trans. [3], vi. 6).

2 Cf. Glaus, Zeitschr. f. anal. Chemie, xvii. 314.

3 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. Glucoses. — 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.1 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. § 197.) If such
substances as tannic acid, etc., have to be removed, it is best to
precipitate a portion of the aqueous extract with basic 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 cc. of water represents 10 cc. 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. 10 cc.
of copper solution indicate 0'05 gram grape-sugar. Should the
final disappearance of the blue colour be concealed by dark
colouring matter, etc., 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, cvi. 75 (Pharm. Journ. Trans. [1], ix. 419) ;
Graeger, N. Jahr. f. Pharm. xxix. 193 ; O. Schmidt, ib. 270 ; Stsedeler u.
Krause, Annalen d. Chem. u. Pharm. Ixix. 94 ; Pellet. Journ. de Pharm. et
de Chimie, 4te Se*rie, xxvii. 460 (Journ. Chem. Soc. xxxiv. 612).

§§ 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 J per cent. If a preliminary experi-
ment shows it to be more concentrated, it should be diluted to
about this strength.1

The estimation may also be made gravimetrically, by quickly
filtering off the cuprous oxide, washing with water, drying and
converting into cupric 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
Brunner2 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.3 317 parts by weight of copper,
357 of cuprous oxide or 397 of cupric oxide indicate 180 of
glucose, 171 of saccharose or 162 of starch, etc. (§ 200).

§ 84. Other Methods of Estimating Glucose. — Glucose may also
be estimated by Knapp's reagent,4 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 as nearly 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.

2 Zeitschr, f. anal. Chemie, xi. 32 (Journ. Chem. Soc. xxv. 928).

* Compare also Weil, ib. 284 ; Mohr, ib. xii. 296 ; Jean, ib. Ill ; Lagrange,
ib. xv. Ill ; Briicke, ib. 100 ; Maschke, ib. xvi. 425. (See Journ. Chem.
Soc. xxv. 1121 ; xxvii. 292 ; xxxi. 805, ib. 116 ; xxxii. 930.)

4 Annal. d. Chem. u. Pharm. 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 Fehling's.

74 SUBSTANCES SOLUBLE IN WATER.

mercuric cyanide and 100 cc. of caustic soda (sp. gr. 1-145) in a
litre of water ; 0-4 gram of the cyanide = 40 cc. of solution mdi-'
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 Sachsse1 contained a large excess of alkali, which rendered the
estimation of dextrose and levulose in the presence of saccharose
inaccurate. Heinrich2 therefore altered the composition by re-
ducing the amount of alkali to a minimum, and directed that a
litre should contain 18 grams of mercuric chloride, 25 of iodide
of potassium and 10 of caustic 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 cc. indicate
0'0168 gram of invert-sugar.

Glucose may also be estimated gravimetrically by using an acid
solution of a mercuric 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.3
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. Phaxm, 1877, 340.

§§ 85—87. INFLUENCE EXERTED BY SA CCHAROSES. 75

The reagent is said to be without action on cane-sugar, glycerin,
arabin and dextrin.

§ 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
precipitable 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).

§ 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. (Cf. § 207.)

According to Pillitz,1 cane-sugar may be easily inverted by

1 Zeitschr. f. anal. Chemie, x. 456 (Journ. Chem. Soc. xxv. 329). See also
Nicol, 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 (specific 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 hydrochloric 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. Bottger's Test. — The above tests also suffice for the detec-
tion of glucose and saccharose. Bottger'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.)

§ 89. Distinctive Characteristics. — The chief marks of distinction
between the various members of the glucose or of the saccharose
group are to be found in the difference in crystalline form, etc.,
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 crystallization 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.
(Ci §§ 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 crystallization 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 Arabic 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, etc.) will be found lower than the estimation of the
total solids in solution. One or more substances must, therefore,

§§ 90, 91. SOLUBLE MODIFICATION OF ARABIC ACID. 77

generally be present that are soluble in water, not precipitated 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 I cannot help
remarking that in some cases a substance seemed to me to be
present which, after evaporation of its alcoholic 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, etc., 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.1 The further investigation of this substance is a
desideratum for plant-analysis.

But in thus assuming the presence of such an 'arabic 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 calculated 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.

§91. Mannite. — Another substance, however, which is of not
unfrequent occurrence in the vegetable kingdom, would similarly
elude detection by the foregoing experiments with the alcoholic and
aqueous extracts, as it is almost insoluble in cold absolute alcohol
but is not precipitated from its aqueous solution by the addition
of either spirit or lead salts. The substance referred to is mannite.
If 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 precipitating
the aqueous solution with alcohol and basic acetate of lead,

1 Compare rny ' Chem. Beitriige z. Pomologie,' Dorpat, 1878 ; Verlag d. Dor-
pater Naturforscher Gesellsch. ; and Pfeil, ' Chem. Beitrage z. Pomologie,'
Diss. Dorpat, 18 SO.

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 crystal-
lize in the cold. But an accurate result cannot be expected, since,
in addition to other errors, mannite may be produced in consider-
able quantity by the fermentation of cane-sugar.1 For particulars
of some substances allied to mannite see § 212.

The method of examination for bitter principles, 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. If 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 mercuric 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 obr
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).

§§ 92, 93, 94. ESTIMATION OF ALBUMEN. 79

the property of absorbing aniline-violet (protoplasm generally
assuming a bluish-violet, the cell-nucleus a reddish tint), carmine,
cochineal, picro-carmine, etc. Note should also be taken of the
form in which the albumen occurs, whether crystalline or
amorphous, etc. (See also §§ 74, 90, 95, 194.)

Protoplasm is coagulated by absolute alcohol and by glycerine.
It becomes clear with solution of caustic potash, cloudy with
acetic acid. Nuclei are generally stained more deeply than pro-
toplasm by aniline-violet, etc., and by iodine. They are coloured
deep blue by a solution of haematoxylin (1 : 30) and alum (1 : 10) ;
the former alone also produces the same effect if the section has
been previously treated with picric 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
trichloracetic acid, and by solution of xanthogenate of potassium.
The precipitate produced by the last reagent becomes flocculent
on heating to 30° (Zoller). (See also §§ 95, 231, 232.)

§ 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 hydrochloric acid, then with 40 per cent, spirit,
dried and weighed, deducting ash (§ 225 et seq.). If hydrochloric
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. (Of. §§ 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 hydrochloric 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, 3 7 '5 cc. glacial acetic acid, 400 cc. spirit made up to a
litre with water) added as long as a precipitate 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 precipitated by
hydrochloric acid or by boiling with acetic acid. (Compare also
the remarks on peptone in § 232.)

As already observed in § 51, in working with substances con-
taining a large quantity of tannin, the results obtained by pro-
ceeding as directed in §§ 92, et seq., 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 §§ 96, 224.

Amongst the substances which facilitate the solution of albumen
we may include arabin. Giinsberg1 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 precipitated albumen when
added in excess.

§ 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 §§ 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, etc. 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.

§ 97. ESTIMATION OF AMMONIA.

81

§ 97. Ammonia.1 — A portion of the aqueous extract (§ 92) is
mixed with two volumes of alcohol and filtered. To the filtrate
and washings calcined magnesia is added, and the ammonia
distilled off into a receiver containing a measured quantity of
normal sulphuric or hydrochloric 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 A should not be more than half full of magnesia

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 & are free from alkaline reaction.
The estimation may be completed in either of the two following
ways :

(a) 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 SOLUBLE IN WATER.

ence the amount of ammonia may be calculated in the usm
way.

(b) The ammonia may be distilled into hydrochloric acid; th(
liquid evaporated to dryness, the residue alternately moistem
and dried two or three times, and the chlorine estimated volu-
metrically by nitrate of silver and chromate of potash. From th(
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
volumetric sulphuric acid under a bell jar. The ammonia liberated
by the lime is absorbed by the sulphuric 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 admitted1 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 hydrochloric 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 calculated and deducted.

If the precautions mentioned have been observed, the first
method (a) will generally yield satisfactory results.

§ 98. Amido-Compounds, etc. — The foregoing estimation will be
inaccurate if the material under examination contains amido-com-
pounds, etc., 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.

§§ 98. ESTIMATION OF AMIDO-COMPOUNDS, ETC. 83

etc., thus liberated, yield with perchloride of platinum double salts
(§ 183) that are soluble in ether-alcohol, and error may therefore
be frequently avoided by precipitating a second portion of the
distillate with excess of perchloride of platinum, evaporating on
the water-bath, extracting the residue with ether-alcohol, drying
and weighing instead of titrating the excess of acid with an alkali.
If 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, etc. 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-alcohol and of a higher molecular weight
than ammonia would be indicated. In the method of deter-
mining ammonia described in § 97, b, 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. Nitric Acid. — For the estimation of nitric acid another
portion of the aqueous extract of § 71 is taken and treated by
Schulze's1 or Wulfert's2 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 cc. This is then introduced into the flask A of the

1 Zeitschr. f. anal. Chem. vii. 392.

2 Landw. Versuchsstationen, xii. 164.

6—2

84 SUBSTANCES SOLUBLE IN WATER.

apparatus recommended by Schulze1 (Fig. 3), a weighed quantity
of powdered aluminium added, and solution of caustic soda slowly
from the deficit in the amount of hydrogen yielded the

run in

Fig. 3.

nitric acid present may be calculated. The following are the
details of the operation :

A measured quantity of solution of caustic soda is introduced
into the pear-shaped flask B. The end of the glass-rod c is
accurately ground into the delivery-tube of B, 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.

§§ 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 A (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 be deducted, and the remainder corrected for temperature,

rig. 4.

pressure, and tension of water-vapour. A previous blank experi-
ment having shown the amount of hydrogen obtainable from the
aluminium taken, the nitric acid may be calculated from the
deficit, 4 molecules of hydrogen corresponding to 1 of nitric
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 powdered 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
hydrochloric 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 tube a. The
longer leg of the latter is similarly connected with a second bent-
glass tube c, communication being regulated by a clip at b. 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 cc. 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 cc. of the iron solution allowed to enter.
The precipitating glass is then filled with hydrochloric acid
(sp. gr. 1*12), and 25 to 40 cc. introduced in a similar manner, so
to sweep the iron solution out of the tubes into the flask. After
closing the end of the tube c with an indiarubber stopper, it is
introduced into a mercury-bath and brought under a cylinder B,
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 5,
and regulating the pressure with the finger and thumb, the
mercury is allowed to rise in the tube so as to drive most of th
hydrochloric acid into the flask ; it must, however, itself
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. I
is then certain that all the nitric oxide that has been formed
been driven into B. The latter is provided with a glass-tap d,
and can be connected air-tight with a measuring tube /. Aft
cooling, the measuring tube filled with mercury is fitted on
the cylinder, and the nitric oxide transferred to it by opening t
tap and sinking the cylinder. The amount of nitric acid ma;
then be calculated from the volume of nitric oxide found.1

§ 101. Sclerotic, Cathartic Acid, etc. — If 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 nitric acid in cultivated plants, see also Schloessing,
Journ. f. pract. Chem. lii. 142 ; Friihling und Grouven, Landwirthsch.
Versuchsst. ix. 9, and 150 (1867) ; Keichardt, Zeitschr. f. anal. Chem. ix. 24
(1870) (Journ. Chem. Soc. xxiv. 439).

§ 102. EXAMINATION FOR INULIN. 87 '

cipitated in §§ 93, 94, or certain amido-acids, such as sclerotic
or cathartic acid, etc. (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 precipitated
by the addition of three volumes of alcohol; and if for every
100 cc. of mother liquor a correction of O'l gram of inulin is
made, it may be thus estimated with tolerable accuracy.1

Characters. — Inulin is not precipitated in a gelatinous or curdy
form, but in a pulverulent condition. It has already been ob-
served that an aqueous solution is IsBvo-rotatory, and that boiling
with a dilute acid converts it into laevo-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 extraction 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-crystals, 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
sphaero-crystals, 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.2

1 Compare my ' Materialien zu einer Monographic des Inulins.' St. Peters-
burg, 1870.

2 Compare Annal. d. Chem. u. Pharm. clvi. 190.

88 SUBSTANCES SOLUBLE IN DILUTE SODA.

VI.

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 O'l to 0-2 per cent.)1 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 nitrate 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 precipitate 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. — If Lassaigne'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 §§ 22G et seq; 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 calculated from the nitrogen
in the residue insoluble in water, as directed in § 96. If 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 SODA. 89

explanation of this is to be found in the fact alluded to in § 92 et
sey., viz., that the material treated according to § 103 has been ex-
hausted with ether and alcohol 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 subjected to the action of ether, etc., 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,1 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
a 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 Treffner2 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. (Of. §§ 232, 238.)

§ 107. Substances Dissolved ly Dilute Soda, not Precipitated ly
Alcohol — The nitrate 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 caustic
soda, not precipitated by acetic acid and alcohol. If the residue
dissolves completely in a few cc. 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, etc., subsequently quoted.

2 Dissertation. Dorpat, 1831.

€0 SUBSTANCES SOLUBLE IN DILUTE SODA.

of soda) is sometimes a decomposition product of metaralic acid or
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
albtfminoids. (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 polyporic acid, isolated by Stahlschmidt,1 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 amylic alcohol, but dissolved by dilute
ammonia, forming a violet liquid, from which it is precipitated
by hydrochloric acid. It crystallizes 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, shoAv
behaviour similar to that of the phlobaphenes ; but in distinguis
ing them we may take advantage of the fact that the majority of
the so-called humic substances contain hydrogen and oxygen
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.

1 Annal. d. Chem. und Pharm. clxxxvii. 177 (1877) (Journ. Chem. Soc.
xxxii. 620).

§§ 109, 110. EXTRACTION WITH DILUTE ACID. 91

VII.

EXAMINATION OF SUBSTANCES SOLUBLE IN DILUTE HYDRO-
CHLORIC ACID j 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 hydrochloric acid. It is advisable 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.1

§ 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 hydrochloric 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 a known quantity of acetate of soda
sufficient to convert all the hydrochloric acid into chloride of
sodium. The oxalate of calcium, 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 (O'l 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 Nageli's ' Monographic der Starkekorner,' Basel, 1858 ; and Vogl, Zeitschr.
d. osterr. Apoth. Ver. 1866, pp. 290, 310.

92 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 seq.) have been dissolved by
dilute hydrochloric acid.

Instead of estimating the oxalate as carbonate or oxide, the
washed precipitate may be dissolved in dilute sulphuric acid, and
the oxalic acid determined by titration with permanganate of
potassium. (Of. §§ 81, 219.)

Microscopical Examination. — Oxalate of calcium is always de-
posited in plants in the crystalline condition, and its presence
may therefore be confirmed by microscopic examination. The
crystals must be insoluble in water, alcohol, and ether, but soluble
in dilute hydrochloric 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 Parardbin. — If the
oxalate of calcium 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 collected 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 precipitate. 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
precipitated pararabin. Should that be the case, they may be

§§ 112—115. CALCIUM, PARARABIN, ETC. 93

estimated by determining the nitrogen in a portion of the preci-
pitate. (Cf. § 233.)

§ 112. Estimation of Pararabin alone. — If pararabin1 alone is
present, the estimation may be conducted as described in § 111,
with the exception, of course, that the determination of calcium is
unnecessary. After precipitation with alcohol, pararabin swells
in contact with water, but does not dissolve unless an acid be
added. It is precipitated by alkalies, and does not yield arabinose
under the influence of dilute sulphuric acid. (Cf. § 245.)

§ 1 1 3. Estimation of Starch and Oxalate of Calcium. — If pararabin
is absent, but oxalate of calcium 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 calcium 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 needs
no special description.

§ 114. Estimation of Oxalate of Calcium, Starch, and Pararabin. —
The following is the method I have adopted when oxalate of
calcium, 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 hydrochloric
acid and boiled as directed in § 113, the glucose being finally
estimated with Fehling's solution and calculated into starch.

§ 115. Estimation of Starch alone. — If a vegetable substance,
especially one rich in mucilage, metarabic 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. xxviii. 1179).

94

SUBSTANCES SOLUBLE IN DILUTE ACID.

ment with various solvents, a method that I published in 186 11
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 hydrochloric 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 soluble partly in alcohol, partly in water, whilst
the starch itself is not attacked. (See § 243.)

1 .Tourn. f. Landwirthsch (May, 1862), and Pharm. Zeitschr. f. Russland,
i. 41. For the estimation of starch as glucose after the action of dilute
sulphuric 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 hydrochloric acid — 1 per cent, of the
weight of the liquid. Both Sachsse and 'Niigeli found that the analyses of
starch were more accurately expressed by the formula 6C6H1005 +• H2O, than
by that usually adopted, viz., C6H1005.

LIGNIN, CELLULOSE, ETC. 95

vm. ,

DETERMINATION OF LIGNIN AND ALLIED S 17: STANCES AND
OF CELLULOSE.

§ 113. Lignin, Incrusting and Cuticular Substances. — 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 2 to 3 days do net-suffice, the chlorine-
water must be drawn off and replaced by fresh, md this treat-
ment repeated if necessary. It is finally colle.ied on a tared
filter, and washed first with .water, then with verjf dilute (0*3 per
cent.) solution of caustic potash until the washinls are colourless,
the alkali being ultimately removed by pure w: Jer. The loss in
weight after drying represents the amount of li- \iin, 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. Russow1 recommends the object
to be placed on a slide with a drop of dilute aqueous solution of
aniline-red. A drop of ^ycerine is then brought into contact
with the edge of the coverslip on the slide, and left for twenty-
four hours. Stiles2 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.

2 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 alcoholic 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 directed 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.

Wiesner1 has described a qualitative reaction for woody tissue,
which consists in moistening the section with a 0*5 per cent,
solution of phloroglucin, and subsequently treating with hydro-
chloric acid. The lignified tissue assumes a reddish 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, etc., 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 cc. of nitric acid
(sp. gr. 1*16 to 1 *18) ; 1 to 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 continu
long enough, it may be diluted with water and filtered, taking
care to pour the supernatant liquid on to the filter, leaving th
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), etc. (See §§ 245, 246.) The residue
on the filter consists of cellulose with a little ash (silica, sand,
etc.), that may be estimated and deducted. (See also § 248.)

1 Zeitschr. f. anal. Chem. xvii. 511, 1878 (Journ. Chem. Soc. xxxiv. 612).

§118. CONCLUDING REMARKS. 97

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. T 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, agriculture,
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 calculating their analyses,
as is frequently done, to the fourth and even fifth place of deci-
mals. Such calculations 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 calculations 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 specimen under examination being taken as a representative
of the drug. Attention must be specially drawn to the fact that

7

98

CONCLUDING EEMAEKS.

in different years and different localities the proportions in whicl
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.

§ 120. FIXED OIL, ETC. 99

IX.

SPECIAL METHODS FOR THE ESTIMATION OF CERTAIN CONSTI-
TUENTS OF PLANTS, SUPPLEMENTARY NOTES TO THE PRE-
CEDING EXPERIMENTS.

FATS AND THEIR CONSTITUENT ; CHOLESTERIN, FILICIN, ETC.

§ 120. Estimation of Fixed Oils.— For reasons given in § 8, I
recommended the use of benzene some twenty years ago1 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
resins, etc. (Cf. § 36.) The use of benzene was afterwards
advocated by Hoffmann2 also, who gave it the preference over
ether and bisulphide of carbon. Other methods for estimating
fixed oils have been described by Munch. 3 Various forms of
apparatus that may be used have formed the subjects of .commu-
nications from Storch,4 Wagner,5 Simon,6 Tollens,7 Schulze,8
Tschaplowitz,9 Medicus,10 Siewert,11 Hirschsohn,12 Keyser,13 and
others.

The apparatus represented in Fig. 5 is that last devised by
Tollens. It consists of a weighed flask, A, holding about 100 cc.,
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

1 Pharm. Zeitschr. f. Kussland, i. 44, 1862 ; Anm. Zeitschr. f. anal. Chem.
i. 490.

2 Zeitschr. f. anal. Chemie, vi. 368, 1867.
» N. Jahrb. f. Pharm. xxv. 8, 1866.

4 Zeitschr. f. anal. Chemie, vii. 68, 1868. 5 Ibid. ix. 354, 1870.

6 Ibid. xii. 179, 1873 (Journ. Chem. Soc. xxvii. 293).

7 Ibid. xiv. 82, 1875, and xvii. 320, 1878. 8 Ibid. xvii. 174, 1878.
9 Ibid, xviii. 441, 1879. 10 Ibid. xix. 163, 1880.

11 Landw. Versuchsst. xxiii. 317, 1879 (Journ. Chem. Soc. xxxvi. 558).

12 Archiv d. Pharm. [3], x. 486, 1877. 13 Farav. Tidskr. WSO^op, 9 and 19.

100

FIXED OIL, ETC.

Fig. 5.

§ 122. ELAIDIN, TEST FOE, 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 circular 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 nitric
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, Massie1 observed the following
reactions :

On agitating the oil with the nitric 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, ichite or slightly yellouish-green,
or distinctly green; ground-nut oil and poppy-seed oil, reddish;
castor and sesame oil, yellowish or yellowisli-wanye ; 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
1 Journal de Pharm. et de Chim. [4], xii. 13, 1869.

102

FIXED OIL, ETC.

shaken at intervals and finally set aside,
tions were made :

The following observa-

Almond

Hazelnut

Sunflower- seed

Olive

Ground-nut

Poppy

Castor

Sesame"

Apricot

White mustard

Camelina sativa

Walnut

Beech

Kape

Colza

Linseed

Black mustard

Cotton-seed

Hemp

After 20 to 30 mins.
white or pale-greenish

>5

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

After 1 hr.
white.

»>

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.

The following oils solidify : almond in 1-J hr., hazelnut in 1 hr.,
olive oil in 1 hr., ground-nut in 1J hr., sesame in 2?7 hr., apricot
in If hr., beech in 6 hr., rape in 3 hr., colza in 3| In-., cotton in
1J hr. ; the remainder do not solidify at all.

§ 123. Behaviour to Sulphuric Acid. — Casselman1 observed the
following rise in temperature when 50 cc. of the oil were mixed
with 10 cc. of cone, sulphuric acid :

Linseed from 14° to 132° to 134'.
Sunflower „ „ 92°.
Poppy „ „ 92°.

Olive „ „ 48°.

Almond „ „ 59 .

With the oil from peony-seed Stahre and myself 2 observed a rise
to 68°, whilst almond oil rose to 48°.

§ 124. Behaviour to lleagents mentioned in § 12. — Casselman has
made the following observations with the reagents mentioned in

§ 12 :

1 Pharm. Zeitschr. f. Kussland, 299, 1867 ; Zeitschr. f. anal. Chemie. vi. 479.
See also Chateau.

2Archiv d. Pharm. [3], xiv. 412, 531, 1S79 (Journ. Chem. Soc. xxxvi.
1043).

124. BEHAVIOUR TO REAGENTS.

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104

FIXED OIL, ETC.

Stannic 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 phosphoric
acid forms a sort of emulsion with linseed and poppy oil, but not
with the others.

Warming with mercuric 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.

Bieber1 used nitric acid of sp. gr. 1*4, and also a cooled mixture
of equal parts of cone, sulphuric and fuming nitric acid in the pro-
portion of 1 volume of reagent to 5 of oil.

Hauchecorne2 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, a
flesh colour ; sesame", bright red ; ground-nut, greyish-yellow ; and
beech-nut oil, an ochre red. According to Cohne, 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.

Basoletto3 observed that sesame" 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 nitric acid
containing sugar, sesame 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 nitric 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 delia Soc. Adriatic, i. 178, 1875.

§ 124. BEHAVIOUR TO REAGENTS. 105

almond and castor oil produce no alteration. According to
Vidan1 hydrochloric 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-
dowski2 and Walz.3 The latter found that on adding a few
drops of the reagent, which should be of a syrupy consistence, to
2 or 3 cc. of the oil to 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.4 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
{rilmour,5 of the polariscope see Buignet,6 of cohesion figures see
Tomlinson,7 Kate Crane,8 and Moffat.9

8 125. Free Fat-acid. — The presence of free fat- acid may be

1 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.

3 Amer. Journ. Pharm. xlvi. 25,' 1874.

4 Compare Hager, ' Untersuchungen ' (Griinther Leipsic, 1874), vol. ii. 510.

5 Pharm. Journ. and Trans. [3], vi. 981, and Jahresb. f. Pharm. 362.
1876.

6 Journ. de Pharm. et de Chim. xl. 252, 1862 (Amer. Journ. Pharm. xxxiv.
140).

7 Pharm. Journ. and Trans. [2], v. 387, 495.

8 Ibid. [3], v. 243, and Jahresb. f. Pharm. 289, 1874.

9 Chem. News, xviii. 473.

106

FIXED OIL, ETC.

detected, according to Jacobson,1 by shaking with powdered
rosaniline. Oil containing free fat-acid is coloured red.

Rumpler2 employs carbonate of soda, which does not emulsify
oils containing no free fat-acid.

Geissler3 estimates the free fat-acid by diluting with 2 or 3
volumes of ether and titrating with alcoholic potash, using an
alcoholic 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 alcoholic 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 alkali is present neither fat nor
soap will be taken up by the ether.

Schulze5 directs attention to the fact that the estimation is
inaccurate if the material contains vegetable wax yielding an
alcohol (§ 14) on decomposition with an alkali, on account of the
influence the latter exercises on the solubility of cholesterin in
spirit. Schulze recommends the conversion of the impure cho-
lesterin into benzoate of cholesteryl by heating with benzoic 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 recrystallization from ether the cholesterin may
be liberated by heating with alcoholic 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 prc
portions in vegetable substances. (Beneke obtained 1'5 grai
from 2,500 grams of grey peas.) It is insoluble in water, crystal-
lizes from alcohol in silky needles and plates (belonging to th(
rhombic system), melts at 137°, and is, in alcoholic solutioi
laevo-rotatory (aD = 36'61°). Warmed with a mixture of 1 voi

1 Chem.- tech. Eepert. i. 84 ; Zeitschr. f. anal. Chemie, xvii. 387, 1878.

2 Zeitschr. f. anal. Chemie, ix. 417, 1870.

3 Ibid. xvii. 387, 1878 (Journ. Chem. Soc. xxxiv. 334).

4 Med.-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. ;

§ 126. FIIYTOSTERIN, ETC. 107

cone, sulphuric 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-
chloric 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.1
After trituration with sulphuric acid cholesterin is coloured red
by the addition of chloroform.

Phytosterin, a substance allied to and probably homologous with
cholesterin, was discovered by Hesse2 in the Calabar bean. Its
solubility is, on the whole, similar to that of cholesterin, with
which it has occasionally been confounded. It melts at 133°, and
is somewhat less powerfully laevo-rotatory («D = 34*2°).

Filicin is another substance soluble in petroleum spirit ; it is
extracted, therefore, together with the fixed oil, and is partially
deposited in crystals on evaporating such a solution ; an appre-
ciable quantity, however, remains dissolved in the fixed oil.
Experiments made at my instance by Kruse,3 with the object of
devising a quantitative separation of filicin from fixed oil, were
unsuccessful ; all the liquids employed (acetone, acetic ether,
ether, heavy petroleum oils, bisulphide of carbon, etc.) dissolved
both substances. Attempts to separate the fixed oil from the
filicin 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. Ferric chloride colours the alcoholic solution red, and

1 Zeitschr. f. anal. Chemie, xvii. 173, 1878, and Ritthausen, ' Eiweiss-
korper,' 98.

2 Annal. d. Chem. und Pharm. cxcii. 175, 1878 (Journ. Chem. Soc. xxxiv.
850). For paracholesterin, see ibid, ccvii. 229, 1881. Hesse, ibid. ccxi. 283 ;
Schulze and Barbieri, Ber. d. d. Chem. Ges. xv, 953, 1882.

8 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.

4 Fltickiger 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 ting(
It is decomposed by fusion with potash, yielding, amongst othe
substances, butyric acid (the same is the case with filicin).

Euphofbon1 is likewise soluble in petroleum spirit, and fi
so in ether, benzene, chloroform, acetone, and glacial acetic ack
but not in aqueous alkalies. It dissolves in concentrated sulphui
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 ethe
but insoluble in water, even in the presence of a little alkali ; it
dissolved, however, by hot concentrated solution of potash.
Helenin melts at 110°, crystallizes in colourless needles, and dis-
solves in cone, sulphuric acid, with production of a red colouration.
Hydrochloric acid-gas is also said to colour helenin red.2

Coumarin may be recognised by its odour and by its colourless
rhombic crystals. 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 salicylic acid
(§ 26). For the allied melilotic add compare Zwenger.3

Styrol also is characterized by its aromatic 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 chromic
acid it yields benzoic acid and other products of decomposition
(§ 26).

For myroxocarpin, see Stenhouse and Scharling;4 for diotmin,
Landerer5 and Fluckiger;6 for kdmpferid, 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;
cxcii, 193, 1878 (Amer. Journ. Pharm. 1. 552). See also Albert! and Dragen-
dorff, Pharm. Zeitschr. f. Russland, ii. 215, 1863 ; and Fluckiger, 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, andxcvii. 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. Iviii. 52 ; Ber. d. d. chem. Ges. xiv. 2385.

§§ 127, 128. CAOUTCHOUC, ETC. 109

C. Schmidt ;: for angelicm, which has been proved to be identical
with hydrocarotin, see Brimmer ;2 for carotin, see Husemann.3 The
last-named substance forms red crystals, soluble in benzene and
bisulphide of carbon. It dissolves in cone, sulphuric acid, with a
purplish-blue colour, and is also coloured blue by sulphurous-acid-
gas.

Anemonol, which occurs in many Kanunculacese, may also be
mentioned here. It is an oily acrid liquid, volatile with the vapour
of water, and gradually changing in aqueous solution to crystalline
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.4

For capsicin and capsaidn see Thresh ;5 for amynn and Imjaidin
see Buri.6

§ 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 Eeichardt,7 and Neubauer and
Borgmann.8 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.

2 N. Eepert. f. Pharm. xxiv. 665, 1874 (Pharm. Journ. and Trans. [3], vii. 91).

3 Annal. d. Chem. und Pharm. cxvii. 200, 1861.

4 Compare Fehling, Annal. d. Chem. und Pharm. xxxviii. 278, 1841 ; Miiller,
Chem. Centrlb. 618, 1850 ; Erdmann, Journ. f. prakt. Chem. Ixxv. 209. See
Amer. Journ. Pharm. xxxiv. 300 ; xxxi. 440.

5 Pharm. Journ. and Trans. [3], vi. 941, vii. 473.

6 N. Eepert. f. Pharm. 220, 1875 (Pharm. Journ. and Trans. [3], vii. 157).

7 Archiv d. Pharm. [3], x. 408 ; [3], xi, 142, 1877.

8 Zeitschr. f. anal. Chemie, xviii. 442, 1878. See also Pasteur, Annal. d.
Chem. und Pharm. Iviii. 330, 1864.

110 FIXED OIL, ETC.

as possible, as glycerin loses weight even in a vacuum. Compare
also Griessmeier and Clausnitzer.1

§ 129. Wax.—Cdyl alcoJwl (§ 14) melts at 48° to 49°, and at 54C
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.

Konig and Kiesow found a substance in meadow-hay which they

considered to be cerotene, or a 'paraffin' of the composition C20H42.5

* Hirschsohn has endeavoured to find distinctive characteristics

for certain vegetable waxes that find application in the arts,3 wit

the following results :

Wax from Myrica quercifolia. — Soluble in 10 parts of boilim
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 alcoholic solution gave a precipitate with alcoholic fei
chloride (1 in 10), which did not dissolve on warming.

Wax from another sp. of Myrica yielded 19-88 per cent,
alcohol, 6870 per cent, to petroleum-spirit. Ferric chloric
coloured the alcoholic solution black.

Wax from Myrica cerifera yielded 7 '16 per cent, to alcohol
41*62 per cent, to petroleum spirit. Ferric chloride coloui
the alcoholic solution brownish.

Wax from Rhus succedanea (Japan wax) resembled the thi
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 onh
partially dissolved.

Wax from Aleurites lacclfera. — The solution in chloroform
became turbid on cooling ; the addition of an alcoholic 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),
Zeitschr. f. anal. Chemie, xx. 58, 1881 (Journ. Chem. Soc. xl. 470).

2 Ber. d. d. chem. Ges. vi. 500, 1874. For vegetable wax see also Ludwi§
Archiv Pharm. [3], i. 193.

3 Pharm. Journ. and Trans. [3], x. 749.

§§129, 130. WAX, ETC. Ill

Carnauba wax, behaved similarly to chloroform and alcohol, but
acetate of lead caused no cloudiness. It was partially soluble in
ether ; the ethereal solution became turbid on the addition of
alcohol. Cold alcohol dissolved 3 '25 per cent., petroleum-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 alcohol dissolved 9*7 per cent, petroleum spirit 3*32 per cent.

For cerosin from the sugar-cane see Avequin,1 Dumas,2 and
Lewy.3

Wax may be recognised microchemically 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.)

§ 130. Okie and Linoleic Adds. — Oudemans4 has adopted the
following method for the estimation of oleic acid. The soap
obtained by saponifying about 10 grams of the fat with potash is
decomposed with sulphuric 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 alcoholic solution a little water and an excess of acetate of
lead is added. The lead precipitate is collected and dried ; and
from a weighed portion the oleate of lead is extracted by boiling
with ether. The oleic acid may be calculated 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, palmitic and
myristic acid, from the soap, dissolving the -mixed fat-acids in
alcohol, carefully evaporating, allowing the palmitic and myristic
acids to crystallize 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.5

1 Annales de Chimie et de Physique, Ixxv. 218.

2 Ibid. 238 ; Annal. d. Chera. und Pharm. xxxvii. 170, 1841.

3 Ibid. (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) ;
Schiller, Jahresb. f. Pharm. 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
oleic acid (§ 15). (Myristic and other fat-acids may however be
distilled in vacuo.)

Oleic and stearic acids may be separated, according to David,1 by
precipitation from alcoholic solution with glacial acetic acid (1
volume to 3 of 95 per cent, spirit). Oleic acid is not thrown out
even by the addition of 2 *2 cc. of a mixture of equal volumes of
glacial acetic acid and water to 3 cc. of alcoholic solution. Under
these circumstances 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,2 Barfoed3 and
Gladding.4 The following particulars 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 1 0 parts of cold
spirit of the same strength, but is precipitated on adding water
containing hydrochloric acid.

b. If 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 alcoholic carbonate of soda solution and
decomposing with hydrochloric 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 calcium in 15
of 80 per cent, spirit to a hot solution in spirit of the same
strength, and cooling, the calcium salts of both fat-acids separate
out, whilst that of the resin acid remains in solution.

d. If stearic and palmitic acid and resin are dissolved in soda,
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. ccvii. 1873 (Journ. Chem. 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

mixture 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 oleic from
stearic and palmitic acid in absence of resin. If only a small
quantity of oleic acid is present, the resin may be estimated by c.
On decomposing the lime salt with an acid, a little oleic 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 chlorophyll is still involved in considerable obscurity, I treated
it in § 20 as a homogeneous body, and at the same time pointed
out that the chlorophyll-granules observable under the microscope
contain solid albuminous substances, starch, etc., in addition to
chlorophyll.

It has been satisfactorily proved by Fremy1 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

1 Comptes Rendus, 1. 405,1860, Ixi. 188, 1865; Journ. f. prakt. Chem.
Ixxxvii. 319, 1862. See also Kromayer und Ludwig, Archiv d. Phai-m. clvi.
164, 1861 ; Ae, Archiv d. Pharni. cxcii. 163, 1870; Kraus, ' Zur Kenntniss
de.s Chlorophyllfarbatoffes,' Stuttgart, 1872 ; Wiesner, Chem. Centralblatt,
3"»:i, 1S74 ; 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

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,1 who assert that they are only products of its
decomposition. Sorby, again, does not consider the existence of
a chlorophyll, a phyllocyanin, or phylloxanthin of definite chemical
composition to be probable, but rather anticipates 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,2 and others, and said to differ spectroscopically 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 crystalline chryso-
phyll and Pringsheim's hypochlorin, are questions involved ii
still greater obscurity.

I restrict myself, therefore, here, to stating that ' chlorophyll y
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. 3

1 Chem. Centralblatt, 299, 316, 331, 1880. - Ibid. 121, 1878.

3 That the chlorophyll 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 Freiny,
do not occur 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, etc., 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.

§ 134. ERYTHROPHYLL, CHLOROPHYLL AN, ETC. 115

After acidulating the alcoholic extract with hydrochloric acid
and diluting with a little water, the chlorophyll may be removed
by shaking with benzene, xanthophyll remaining in the alcoholic
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,1 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 alcoholic filtrate. The residue may be weighed.

§ 134. Erythrophyll, Chlorophyllan, etc. — By first freeing grass
from wax by treatment with ether, and then exhausting with
alcohol, Hoppe-Seyler2 succeeded in isolating from unaltered
chlorophyll a greenish-white colouring matter, sparingly soluble
in alcohol, crystallizing in four-sided plates, and appearing red by
transmitted light. This substance seems to be identical with
Bougarel's3 erythrophyll. Hoppe-Seyler also separated a second
substance, which was more easily soluble in hot alcohol, crystallized
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-spectrum (§§ 148 and 20). Hoppe-Seyler
thinks it possible to make approximate estimations of chlorophyll
by titration with spectroscopic end-reaction.4 Gautier has also

1 Chem. Centralblatt, 121, 1878 ; 741, 1880.

2 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. xxxii. 700).

4 For the chlorophyll contained in certain Floridese, see Pringsheim, he. elf. ;

8—2

116 CHLOROPHYLL.

isolated from the leaves of dicotyledonous plants a crystalline
chlorophyll,1 which Hoppe-Seyler suspects to be a mixture of
erythrophyll, chlorophyllan and wax. Gautier's analyses agree
tolerably well with fhose of Hoppe-Seyler's chlorophyllan.

§ 135. Xanthoplmjll (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, etc. Sulphuric and hydrochloric 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.2 Hartsen thinks
that his chrysophyll is possibly identical with phylloxanthin.

Hypoclilorin. — Pringsheim3 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. In 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 alcoholic
solution assumes a green tinge, and, after the lapse of some time,
is coloured blue by hydrochloric acid.

for the colouring matter of certain Algae, 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,
Holder, 1874.

3 Chem. Centralblatt, 9, 27, 299, 316, 331, 1880. Compare also Jahresb.
f. Wissensch. Bot. 1874. See Quarterly Journ. Mic. Soc. 1881.

§ 136. ETHEREAL OILS. 117

Anthowrithin, 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 hydrochloric acid.

ETHEREAL OILS, VOLATILE ACIDS, ETC.

§ 136. Estimation. — The following estimations are taken from
Osse, 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 0*026 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, 0-0135 (difference, 0*0035). The weight of the
turpentine taken is calculated from the third weighing, 0*0205
gram, to which is added 2 x 0*0035 gram, making a total of 0*0275
gram from 1 cc., or 0*275 gram from 10 cc., instead of 0*277
gram. . A second estimation gave 0*267 gram ; mean 0*271 gram.

II. 0*1268 gram of oil of lemon was diluted to 5 cc. with petro-
leum spirit, and 1 cc. taken for evaporation.

1st weighing = 0'0505
2nd „ = 0-0250 cliff. - 0-0255.
3rd „ = 0*0185 „ = 0-0065.
4th ,, = 0:0165 ,, = 0-002.
5th „ = 0*0145 „ = 0-002.

To the third weighing, 0*0185 gram, there is to be added
2 x 0*002 gram, giving a total of 0*0225 gram from 1 cc., or
0-1125 gram from 5 cc., instead of 0*1268 gram. A repetition of
the estimation gave 0*1275 gram; mean 0*1200 gram instead of
0*1268 gram.

III. 0*166 gram of oil of cinnamon diluted to 10 cc. ; 1 cc.
taken for evaporation.

1st weighing = 0'0317
2nd „ = 0-0171 diff. - 0*0146.
3rd ,, = 0-0163 ,, = O'OOOS.
4th „ = 0-0160 ,, = 0-0003.
5th „ = 0*0157 „ = 0-0003.

The third weighing, 0*0163, represents the quantity of oil
present, since no correction has to be made, as the co-efficient of

118

E THE HEAL OILS.

evaporation is less than O'OOl. 10 cc. would, therefore, contain
0-163 gram instead of 0-166 gram.

§137. Estimation with Bisulphide of Carbon.— Instead of petro-
leum spirit, Osse also tried bisulphide of carbon, as recommended
by Hager J 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, etc. Ethereal oils may
be extracted from their aqueous solutions by petroleum spirit,2
and may therefore be estimated in the aqueous portion of the
distillate (§ 24) by shaking with that solvent and evaporating a
measured quantity of the solution after separation from the
aqueous liquid. I have also employed this method for estimating
the essential oil in the official aromatic 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 O'l 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 cinnamon weighed

after

1 hour at 110° . . . T436 gram.

2 „ „ . 1-4335 „

3 „ „ . 1-4315 „

1 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 ACIDS. 119

I obtained similar results in experiments with cacao butter.
Resin could be almost completely freed from ethereal oil at 100°
to 11 0°, and it was only in the case of oils prone to oxidation,
.such as oil of cloves, that the residual resin was somewhat
heavier than was expected. (See also § 146.)

Drying oils would, of course, increase very appreciably in
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 -,1

Five grams of savin leaves were finely powdered and digested
with 25 cc. of petroleum spirit • I cc. of the solution was eva-
porated. The residue weighed 0*0265 gram (corr.), which de-
creased to 0*0175 gram on heating to 110°. 1 cc. contained,
therefore, 0*009 gram ethereal oil and 0*0175 gram resin, or
4*5 per cent, of ethereal oil and 8*75 per cent, of resin.

§ 139. Separation of Volatile Acids. — Angelic acid melts at 45°
and boils at 185° ; methyl-crotonic acid at 65° and 198° ; crotonic
acid, 16° and 160*5° ; capric, 30° and 268° to 270° ; caprylic, 16°
to 16*5° and 236° to 237° ; cenanthic boils at 223° to 224° ; caproic,
204° to 206° ; valerianic at 175°; trimethyl acetic, 163'7° to 163*8°
(melts at 35*3° to 35*5°); butyric at 163°; isobutyric, 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, etc., 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. Isobutyric 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, etc. The barium, calcium, and lead
salts of some of the acids may be similarly employed ; thus the
barium salt of caprylic acid is soluble in 164 parts of cold water ;2
formate of calcium 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

1 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,1
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 ferric salt
(avoiding an excess). (See also § 34.)

§ 14)0. Identification. — The saturating power of a fatty acid, a
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. In certain cases a determination of the water of
crystallization may prove useful.

By distilling the sodium salts with concentrated sulphuric acid
and absolute alcohol, the ethyl-salts of the acids may be prepared ;
they are not unfrequently of characteristic 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 Alcohol. — For information with
regard to the optical testing of volatile oils see Buignet,2 Franck,3
Fliickiger,4 and Symes.5

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 menthse 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, 93 to 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. ath. Oele,' Berlin, 1872, and Fliickiger'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).

c 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°. l

I found the following proportions of weaker alcohol necessary
to form clear mixtures with the foregoing oils :

Vols. Strength of Spirit.

Oil of Cinnamon .

.3 of 65

per cent. (Tralles).

Cloves

. 2-7 „ 60

Sage .

. 3-1 „ 65

n

Cajeput

. 2-5 „ 65

Marjoram .

. 1-45 , 78

»

Rosemary .

. 1.4 , 78

Lavender .

. 2-3 , 65

"

Mentha crispa .

. 2-7 , 65

,,

Peppermint

. 2-2 , 70

>»

Carawav .

. 0-8 84

Bitter orange

. 0-9

94

v

Bergamot .

. 1-15

78

,,

Lemon (dist.)

. 4-0

91

»

(pressed)

. 2-8

92

,,

Savin

. 1-3

80

>j

Juniper

. 3-0

93

»?

Turpentine

. 3-75

92

n

>

Fennel

. 2-9

85

(at 21° C.)

Anise

. 6-3

85

(at 17-5° C.)

§ 142. Colour-reactions. — I have observed the following colour-
reactions with certain ethereal oils :2
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 greenish-

11 ne 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, myrrh and parsley ; broivnish-
violet with mace; blue or bluish-violet with cubebs, copaiba,
amomum, laurel, sandal- wood and sweet flag ; orange with oil of
worm-seed, oil of cedar-wood ; and with camphor.

J X. Repert. f. Pharm. xxii. 1, 1872 ; Pharm. Journ. and Trans. [3], vi.
541 d seq. See also Godeffroy und Ledermann, Zeitschr. d. allgem. oesterr.
Apotheker Ver. xv. 381 et «<?*/. ; Jahresb. f. Pharm. 394, 1877.

- Pharm. Journ. and Trans. [3], vi. 681 ; Archiv d. Pharm. [3], xii. 289.
See also Hager, Pharm. Centralblatt, 137, 169, 195, 1870 ; and Fliickiger,
Schweiz. Wochenschr. f. Pharm. 261, 1870.

122

ETHEREAL OILS.

Impure Chloral Hydrate1 (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), cinnamon
(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
alcoholic hydrochloric acid in the proportion of 15 to 20 drops to
1 of oil yields colourless mixtures with oil of turpentine, caraway,
coriander, cardamoms (cone, acid, cherry-red), cloves, rosemary
(cone, acid, deep cherry-red) ; yellow mixtures with bergamot
(cone, acid, orange to olive-green), mace (cone, acid, reddish- brown),
dill (cone, acid, cherry-red), bitter orange, cummin (cone, acid,
deep violet) ; brownish-red with oils of cascarilla, lavender, sweet
marjoram, worm-seed, jumper (cone, acid, red) ; rose to deep red or
reddish-violet with oils of cubebs, pepper, copaiba, cedar wood, cin-
namon, nutmeg, thyme, laurel, sweet-flag and myrrh ; red, turning
Hue, with oil of peppermint.

Concentrated sulphuric acid (2 or 3 drops to 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, wTinter-green, lavender,
amomum, cascarilla, nutmeg, thyme, sandal-wood, peppermint,
myrrh, and parsley. Oils of cardamoms, cloves, fennel, anise,
cajeput and laurel produce a violet, cinnamon a green and Hue
colouration.

If a drop of the oil is mixed with 1 cc. of chloroform and 2
drops of cone, sulphuric acid added, similar colours are produced'2
and imparted to the chloroform.

1 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 partially separating
the hydrochloric 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

Fruhde's Reagent1 resembles sulphuric acid in its action ; but the
colours are purer and make their appearance more rapidly. Very
characteristic colours are produced with some oils by sulphuric
acid mixed with Jth of its volume of a 5 per cent, aqueous solution
of ferric chloride.

The oils should be dissolved in chloroform, in which the colour-
ing matter is also soluble and thus seen to advantage.

Oils of pennyroyal, parsley, coriander, fennel, anise, savin and
turpentine cause no colouration in the chloroform, even after the
lapse of some time ; with oils of ledum and peppermint it assumes
a red tinge ; with ledum-camphor, and oils of thyme, cajeput,
galangal, pepper, cubebs, copaiba, juniper, violet or bluish-violet ;
with serpyllum, sweet marjoram, rosemary, caraway, dill, nutmeg,
cloves, worm-seed, cinnamon, green or bluish-green; with oil of
bergamot, etc., olive-green.

Fuming nitric acid (5 drops to 1 of oil) gives specially charac-
teristic colourations with oils of mace and nutmeg (blood-red),
cubebs (green), copaiba (bluish-violet), gaultheria (cherry-red),
cinnamon (carmine), myrrh (reddish-violet), pimento (blood-red),
.and pennyroyal (violet).

Picric acid (0'05 gram to 5 to 6 drops of oil) is easily dissolved
by some oils in the cold (caraway, cardamoms, cloves, rosemary,
mentha crispa, sweet marjoram, anise, star-anise, dill, valerian,
cummin, gaultheria, cinnamon, sweet flag) ; by others only on
warming. Some of the solutions deposit crj^stals on standing
(turpentine, lemon, bergamot, sweet marjoram, mace, dill, galangal,
bitter orange, worm-seed, valerian, cedar-wood, lavender, cajeput,
nutmeg, thyme, laurel and sandal-wood) ; others gradually assume
characteristic colourations : thus oil of mentha crispa becomes
olive-green ; cloves, sweet marjoram, anise, star-anise, nutmeg,
cinnamon, cummin, amomum and thyme, orange; fennel and
myrrh, blood-red ; dill, cascarilla and galangal, brown ; worm-seed,
reddish-brown ; sweet- flag, deep brown ; peppermint, deep grass
green.

Fliickiger2 recommends acting upon a solution of the ethereal
oil in bisulphide of carbon (1 in 15) with sulphuric and nitric acids.
With oil of valerian and nitric acid (specific gravity, 1'2) he
observed a green colouration of the bisulphide, and red of the acid

1 1 cc. cone, sulphuric acid with O'Ol gram molybdate of soda.

2 Schweiz. Wochenschr. f. Pharm. 261, 1870.

124

ETHEREAL OILS.

layer ; with a mixture of both acids, blue. Gurjun-balsam oil
behaved similarly, and oil of cubebs also turned blue with a
mixture of both acids.

Solid iodine added to ethereal oils produces somewhat varying
effects. With some oils, especially terpenes of the formula C10H10,
the action is very energetic, and accompanied by evolution of both
light and heat, whilst with others nothing of the kind is observ-
able. Chromic acid also reacts explosively with certain oils. Some
oxygenated oils(carvolof cummin oil) yield crystalline sulphhydrates
when mixed with alcoholic solution of sulphide of ammonium, from
which the oil may be separated by decomposition with potash.1
If hydrochloric acid gas is passed through ethereal oils,,
crystalline or liquid hydrochlorates are not unfrequently produced,
which may be characteristic of the oil acted upon. The NOC1
group sometimes combines with hydrocarbons of the terpene
series to form compounds of the formula C10H16NOC1, and,
according to Tilden, this reaction also nuiy be employed in dis-
tinguishing ethereal oils. Tilden2 obtained crystalline compounds
with French and American oil of turpentine, with oil of juniper,
sage, caraway, bitter orange, bergamot, and lemon.

For the use of cohesion figures in identifying the various
ethereal oils see Kate Crane3 and Tomlinson.4

§ 143. Fractional distillation. — Linnemann's apparatus5 (fig. 6)
is very serviceable in fractionally distilling ethereal oils (§ 30).
A is a tube of about 40 cm. in length and 1 cm. in diameter ; at
about 32 cm. from one end a second tube, B, is fused on at an
angle of about 80°, so that it can be connected with a condenser..
Just beneath the junction, and at a distance of 20 and 25 cm. from
the end, bulbs are blown. At the upper end a thermometer is
introduced, the bulb of which should be in C. In the lower part
of the tube about 8 cup-shaped pieces of platinum gauze are
inserted. These are intended to receive the condensing vapour
from the liquids of higher boiling points and wash, as it were, the
vapour of more easily volatile liquids. Smaller apparatuses of
30 or 25 cm. in height may be used for special purposes.

For distillation in a partial vacuum the apparatus represented in

1 Compare Jahresb. f. Pharm. 468, 1867.
- Pharm. Jonrn. and Trans. [3], viii. 188.
3 Pharm. Journ. and Trans. [3], v. 242.
3 Annal. d. Chem. und Pharm. clx. 195, 1872.

$ 144. FURTHER EXAMINATION OF ETHEREAL OILS. 125

fig. 7 has been recommended by Thorner.1 The method of using
it is sufficiently intelligible from the figure, and requires no
special description.

§ 144. Further Examination of Ethereal Oils. — For details of the
analysis of ethereal oils by fractional distillation, I refer to the
examination of eucalyptus oil by Faust and Homey er,2 of parsley

Fig. 6.

oil by Gerichten,3 and oil of sage by Muir and Suguira.4 In the
investigation of oil of dill by Nietzky,5 of oil of valerian by
Bruylants (see below) and of arnica by Sigel,6 the fatty acids
present in the oil are included. Ethereal salts Were found by

1 Ber. d. d. chem. Ges. ix. 1868, 1876. See also Bevan, Chem. News,
xxxviii. 183, 1879.

2 Ber. d. d. chem. Ges. vii. 63 and 1429, 1874 (Journ. Chem. Soc. xxvii.
475).

3 Ber. d. d. chem. Ges. ix. 258 and 1477, 1876 (Journ. Chem. Soc. xxx. 78.)

4 Pharm. Journ. and Trans. [3], vii. 265, 1876 ; viii. 191, 1877.

5 Archiv d. Pharm. [3], iv. 317, 1874 (Journ. Chem. Soc. xxvii. 892).

6 Annal d. Chem. und Pharm. clxx. 345, 1873 (Journ. Chem. Soc. xxvii.
377).

126

ETHEREAL OILS.

Renesse1 in the oil of Pastinaca saliva and by Moslinger2 in that
of Heracleum sphondylium.

Fig. 7.

Bruylants included aldehydal substances in his examination of
oil of tansy.3

1 Annal. d. Chem. und Pharm. clxi. 80 ; clxxi. 380 (Journ. Chem. Soc.
xxvi. 642 ; xxvii. 1145).

2 Ber. d. d. chem. Ges. ix. 998. See also Zincke, Annal. d. Chem. und
Pharm. clii. 1, 1869 ; Ber. d. d. chem. Ges. iv. 822, 1872. See also Gutzeit,
' Ueber das Vorkommen des Aethylalkohols im Pflanzenreiche,' Jena, Dufft,
1875 (Journ. Chem. Soc. xxviii. 1245).

3 Ber. d. d. chem. Ges. xi. 449, 1878 (Journ. Chem. Soc. xxxiv. 157).

145. HESIN-ACIDS, ETC. 127

RESINS, ANTHRAQUINONE-DERIVATIVES, BITTER PRINCIPLES, ETC.

§ 145. Resin-acids and the more important methods for their separa-
tion.

With regard to the coniferous resin-acids, the observations made
in § 131 may be supplemented by the following:

Acidic acid1 occurs in lamellar crystals, softening at 129° and
melting at 144°, soluble in alcohol and ether, and forming salts
with most bases. Prolonged heating converts it into its anhy-
dride, which is soluble in absolute alcohol, and was formerly
known as pinic acid. The alcoholic solution of this substance
yields no crystals on evaporation ; it is gradually reconverted into
abietic acid by the continued action of 70 per cent, alcohol.

Pimaric acid, from Pinus pinaster, forms granular crystalline
masses melting at 149°, difficultly soluble in cold, but easily in
boiling alcohol, and soluble in ether. It resembles abietic acid in
most of its properties, but differs in possessing a bitter taste.

For podocarpic acid see Oudemans ;2 gardenin, Stenhouse and
Groves;3 phyllic acid, Bougarel.4

In isolating resin-acids one of the following methods will be
frequently found successful :

a. Successive treatment with spirit of different strengths, finally
adding water and shaking with ether. It will be observed that
resin acids are, as a rule, more easily soluble in dilute spirit than
resin-anhydrides, wax, etc. It was by this method that I suc-
ceeded in isolating mongumic acid from a bark imported from
Madagascar.5 The residue obtained on evaporating the ethereal
extract was treated with 85 per cent, spirit, which left a wax
undissolved. The spirituous solution was evaporated, and the

1 Maly considered the acid formerly known as sylvic acid to be abietic ;
Duvernoy regards it as a modification of pimaric acid.

2 Ber. d. d. chem. Ges. vi. 1122 ; Annal. d. Chem. und Pharm. clxx. 213
(Journ. Chem. Soc. xxvii. 72).

3 Annal. d. Chem. und Pharm. cc. 311 (Journ. Chem. Soc. 1878).

4 Union Pharm. xviii. 262, 1877 (Journ. Chem. Soc. xxxii. 905). A sub-
stance similar to that described under the above name is often met with in the
analysis of herbaceous and leather}' leaves. It is soluble in boiling alcohol,
and separates from such solution, after the wax, on evaporating and cooling.
It crystallizes in colourless scales, dissolves with difficulty in water and
glycerin, is soluble in ether and chloroform, and also in warm potash, but pre-
cipitated by an excess of the latter.

5 Pharm. Journ. and Trans. [3], ix. 816 (1870).

128 RESINS, BITTER PRINCIPLES, ETC.

mass treated with 50 per cent, spirit, in which a little brown
resin was found to be insoluble. To the alcoholic solution ether was
added, and then sufficient water to cause separation. On well
shaking the ether dissolved the whole of the mongumic acid, the
addition of a few drops of acetic or hydrochloric acid facilitating
solution. The mongumic acid was then obtained by evaporating
the ethereal liquid.

b. Treatment of the mixed resins with a solution of soda or potash in
dilute spirit, and recovery of the resin by the addition of acetic or
hydrochloric acid and filtering, or, if very finely suspended,
shaking with ether. I adopted this method in separating a resin-
acid from paeony-seed.1 The mixed resins were treated with
boiling 85 per cent, spirit, and the liquid kept at 0° for some time,
to allow of the separation of a little resin anhydride that had
been carried into solution. To the filtrate water was added till
the spirit was reduced to a strength of 50 per cent., by which the
resin was precipitated. The mass was then dissolved in a solu-
tion of soda in 50 per cent, spirit, again precipitated by the
addition of acid, and finally decolourized in alcoholic solution by
animal charcoal. In adopting this method the requisite strength
of the spirit must be ascertained by preliminary experiments.

c. Treatment of the mixed resins with aqueous soda or potash. —
Any resin dissolved by the alkaline liquid may be generally re-
covered by acidification with acetic or hydrochloric acid. (Com-
pare also § 45). 2 It is, moreover, not unfrequently possible to
obtain sparingly soluble combinations of the resin with silver, lead,
barium, calcium, etc., by adding salts of those metals to the solu-
tion of resinate of soda. This method is sometimes successful in
cases of mixtures of several resin-acids or of a resin-acid with other
resinous substances soluble in solution of soda. The resins present
may be separated by fractional precipitation ; or it may happen
that only one is precipitated by the salt used, in which case, of

1 Archiv d. Pharm. [3], ix. 426, 1879 (Journ. Chem. Soc. xxxvi. 1043).

2 dirt/sin, discovered by Piccard in the buds of the poplar (Ber. d. d. chem.
Ges. vi. 884, 1873; Journ. Chem. Soc. xxvi. 1236) might be isolated by this
method. It is precipitated yellow by acids, is somewhat sparingly soluble in
ether and alcohol, and almost insoluble in petroleum, bisulphide of carbon,
chloroform, and benzene. The latter, when warm, removes the so-called
tectochrysin. An alcoholic solution of chrysin is coloured violet by ferric-
chloride, and gives with neutral acetate of lead a yellow precipitate, soluble in
excess and in glacial acetic acid.

§ 145. RESIN-ACIDS, ETC. 129

course, the others remain in solution ; or finally a mixture may be
precipitated, in which, however, a separation may be effected by
treatment with solvents or by decomposition with carbonic acid,
etc. Hirschsohn met with a case of this description in his examina-
tion of galbanum.1 The resinous portion of the drug was digested
with soda, and to the solution chloride of barium was added till
no further precipitate was produced. From the dried barium
precipitate boiling alcohol dissolved a rather large amount, which
separated again on cooling, and contained only T07 per cent, of
baryta. This portion must have been carried down either
mechanically or in so loose a state of combination that boiling
spirit sufficed to effect a decomposition into acid and base. The
alcoholic solution contained a second resin-acid, which was partly
precipitated on passing carbonic acid through the liquid, and
partly, in masses of fibrous crystals resembling asbestos, on the sub-
sequent addition of water. Boiling 95 per cent, alcohol extracted
it from the dried precipitate. The dilute alcoholic liquid, after
treatment with carbonic acid, was acidulated with hydrochloric
acid, which threw down a flocculent precipitate, soluble in
ammonia. In addition to these three resins a fourth had escaped
precipitation with chloride of barium. It could be separated by
passing a current of carbonic acid through the alkaline solution.

In fractionally precipitating with silver or lead salts attention
should be directed to the percentage of the metal and the melting
point of the resin acid contained in the precipitates. These two
points are frequently of service in identifying acids.

d. The mixed resins may finally be separated by dissolving them
in spirit and fractionally precipitating with alcoholic solution of acetate
of lead.

§ 146. Resins and Gum-resins of Commerce. — The examination
of commercial resins and gum-resins, which generally consist of
ethereal oil and various resinous substances frequently accompanied
by mucilage, sugar, etc., was at my suggestion undertaken and
carried out by Hirschsohn. The following is an abstract of his
results :2

1 Pharm. Zeitschr. f. Russland, p. 225 et seq., 1875 (Pharm. Journ. and
Trans. [3], vii. 369 et seq.).

2 Pharm. Zeitschr. f. Russland, 225 et seq., 1875 ; 1 et seq., 1877. 'Beit-
ra^e zur Chem. der wichtigeren Harze, Gummiharze und Balsame,' Diss.
Dorpat, 1877. Archiv d. Pharm. [3], x. 481 et seq. ; xi. 54 et seq. ; xiii. 288
et seq. Pharm. Journ. and Trans, viii. 389 et seq.

9

130 BE SINS, SITTER PRINCIPLES, ETC.

1. For the determination of the ethereal oil petroleum spirit may
be used as a solvent.1 (See §§ 9, 22, 23, 138.) But, as elsewhere
observed, part of the resin will also be dissolved ; the residue
obtained by evaporating at the ordinary temperature till the
weight is constant must therefore be heated to 110° or 120°, and
the percentage of ethereal oil calculated from the loss. The
amount of resin dissolved by the petroleum spirit, which is thus
simultaneously ascertained, may be of use in estimating the value
of different varieties of a resin or in detecting adulterations (in the
case of copal, the better the quality of the resin the smaller the
percentage oi non-volatile substances soluble in petroleum spirit).
The mixture (of ethereal oil and resin) obtained by evaporating
the petroleum-spirit solution frequently yields colour-reactions with
the reagents mentioned in § 142.

2. The residue insoluble in petroleum spirit is treated with ether
and the substances dissolved estimated. It should be ascertained
if ether takes up all the resin insoluble in petroleum spirit or if a
further portion is removed by subsequent treatment with alcohol.
Gum-resins will of course always leave a residue insoluble in
ether, consisting of sugar, gum, salts, etc. The ethereal solu-
tion should be tested as to its miscibility with alcohol and the
residue after evaporation for colour-reactions as mentioned
inl.

3. The estimation of substances soluble in alcohol, both in the
original drug and after treatment with ether, together with the
qualitative examination of the solution, may likewise yield results
of some value. In the case of gum-resins sugar is one of the prin-
cipal substances extracted by alcohol. (See§§ 70, 83 et seq.; 200
etseq.) It should be ascertained whether a turbidity is produced
by adding ammonia, ether, or alcoholic solution of acetate of lead
to the spirituous extract from the original resin.

4. If a gum-resin is under examination, water will remove gum
(§§ 73 et seq.; and 193 et seq.) and certain salts from the residue
after treatment with alcohol. Note should be taken if a gum
swelling, but not dissolving, in water is present. (See §§ 103 and
193 et seq.)

5. Important results may also be obtained by treating the
original resin with chloroform, ether, or saturated aqueous solution

1 The resin should be rubbed down as fine as possible with powdered glass,
and then macerated with petroleum spirit.

§ 147. P&ONIO-FLUORESCIN, ETC. 131

of carbonate of soda. The latter may cause a colouration or take
up cinnamic acid (detected by the permanganate of potash reaction
(S 26), etc.). For details of the scheme published by Hirschsohn
for the identification of the more important resins and gum-resins,
reference must be made to the original papers, etc., already quoted.

§ 147. Pceonio-fluorescin. — If agitation with ether (§ 44) removes
any substance from solution in caustic alkali it should be ascertained
whether the same can be extracted from a solution in a carbonated
alkali. It was found that pseonio-fluorescin1 could be obtained
much purer by using a carbonated rather than a caustic alkali, as the
latter partially decomposes it, whilst the former does not. Whether
the seeds of other plants contain in their testa a body allied to, or
identical with, pseonio-fluorescin, and possessing, therefore, a strong
fluorescence in ethereal solution, is a matter for investigation.

Pseonio-fluorescin is sparingly soluble in chloroform, benzene,
and cold water (somewhat more freely in warm), but insoluble in
petroleum spirit. It is precipitated from a warm (50°) aqueous
solution by gelatine, but not by acetate of lead or copper. On
boiling with very dilute hydrochloric acid an intense green colour
is developed, which can be extracted by agitation with ether, and
changes to a reddish-violet in contact with acetate of soda. Its
solution in very dilute lime-water, extremely weak ammonia, or
even chalky spring-water, gradually assumes a fine red colour when
exposed to the air.

§ 148. Anthraquinone-derivatives. — In treating the substances
soluble in ether (§§ 36 and 46) with alkaline liquids, any change
of colour, especially to red, should be carefully noted. If such
is the case there is reason to take into consideration the possible
presence of certain anthraquinone derivatives, such as chryso-
phanic acid, emodin, frangulic acid, alizarin, purpurin, etc. They
-are soluble in very dilute alkali, and are precipitated by hydro-
chloric acid from the deeply -coloured (generally red) solutions.
It frequently happens that these bodies do not occur ready-
formed in the fresh substances, or in material that has been care-
fully dried, but are present in the form of glucosides2 (chrysophan,
frangulin, ruberythric acid).

The following are some of the characteristic properties of the
foregoing anthraquinone derivatives.

1 Archiv d. Pharm. [3], xiv. 412.

2 Compare my paper on Analyses of Rhubarb ; Pharm. Zeitschr. f. Russland,

9—2

132 BESINS, BITTER PRINCIPLES, ETC.

Chrysoplianic acid, as obtained from rhubarb, senna,1 etc., is
almost insoluble in water, but if in combination with a base it
can be extracted from aqueous solution by adding a strong acid
and shaking with ether. The solubility in alcohol and acetic acid
varies directly with the strength of the solvent (1 cc. of 86 per
cent, alcohol dissolves 0-00017 gram at 20°; 1 cc. glacial acetic
acid dissolves 0*00046 gram).

Chrysophanic acid is sparingly soluble in petroleum spirit, but
is dissolved by benzene and chloroform, especially when warm.
It can be sublimed in flat rhombic prisms, which melt at 162%
are yellow in colour, and strongly dichroic. It is easily dissolved
by alkaline liquids, both aqueous and alcoholic, with production of
a fine red colour, for particulars of the spectrum of which refer-
ence must be made to Keussler's dissertation. This colouration
in contact with alkali serves as a means of detecting chrysophanic
acid and allied substances microscopically, fout it is preferable to
employ baryta- or lime-water, as with these, bases compounds are
formed which are insoluble in water. ! *f

Emodin agrees with chrysophanic acid in most of its properties,
but may be distinguished by its insolubility in benzene, and
greater solubility in ether and alcohol. It melts at 245° to 250%
and crystallizes in needles from glacial acetic acid.

Erythroretin and Phceoretin may also be obtained from rhubarb ;
they are both sparingly soluble in ether, freely in alcohol ; the
former is coloured purple-red by alkalies, the latter reddish-
brown.2

Chrysarolin occurs in Goa powder;3 it is soluble in boiling
benzene, and forms a yellow solution with cone, sulphuric acid
(chrysophanic acid, red). It is not dissolved by dilute potash^
but with concentrated it yields a yellow solution with a green
fluorescence. On shaking this liquid with air for some time it
turns red, and then deposits chrysophanic acid after acidulation.

65, 97, 1878 (Pharm. Journ. and Trans. [3]. viii. 826), and the continuation of
the paper by Greenish, Pharm. Journ. and Trans. [3], ix. 933.

1 Compare Keussler, ' Unters. d. chrysophansaureart. Subst. der Sennes-
blatter und der Frangulinsaure, ' Diss. Dorpat, 1879, and Pharm. Zeitschr. f.
Russland, 257 et seq., 1878. See also Kubly, 'Ueber das wirksame Princip
und einige andere Best. d. Sennesblatter,' Diss. Dorpat, 1865, and Pharm.
Zeitschr. f. Russland, 429 et seq., 1866 (Amer. Journ. Pharm. xxxvi. 374).

2 Compare Kubly, Pharm. Zeitschr. f. Russland, vi. 6C3, 1867.

3 Compare Liebermann und Seidler, Ber. d. d. chem. Ges. xi. 1603 (Journ.
Chern. Soc. xxxvi. 326).

§ 148. FRANGULIC ACID, ALIZARIN, ETC. 133

Frangulic add can be obtained as an orange-red powder, con-
sisting of small acicular (? hexagonal) crystals, which melt at
255° and are not dichroic. At a temperature of 18° 1 cc. of
glacial acetic acid dissolves 0 '00235 gram, 1 cc. of 96 per cent,
spirit 0-018 gram. The solutions of this substance in aqueous or
alcoholic alkalies are also of a fine red colour, but prove to be
somewhat different from those of chrysophanic acid when ex-
amined spectroscopically. Keussler made the following observa-
tions with aqueous solutions in caustic potash, under the conditions
mentioned in § 22 :

Diminished Undiminished Diminished No colours

Intensity. Intensity. Intensity. observable.

Chrysophanic acid . 0°— 13° 13°— 34° 34°— 38° 48° to end.

Frangulic acid . . 0° — 18° 18° — 38° From 38° to end gradual dimini-

tion of intensity to complete dark-
ness.

Compare Plate I., 1 and 2.1

Alizarin forms orange-red prisms, which are also almost
insoluble in cold water, but soluble in alcohol, ether, benzene, and
aqueous alkalies. They melt at 215°, and can be sublimed with-
out decomposition. Its alkaline solutions are violet, and yield
purple precipitates with salts of calcium, barium and lead. Vogel2
states that the absorption-spectrum of a solution of alizarin in
dilute alcoholic potash shows two dark bands, one of which is
exactly divided by the line d, whilst the other begins a little
before D, and may be traced some distance past that line. (Com-
pare Plate I, 3.) An alcoholic solution of alizarin, after addition
of ammonia, shows an absorption spectrum with a single ill-
defined band in the green between D and F. (Plate I., 4).

Purpurin shows under the last-named conditions two ill-defined
absorption bands to the right and left of E (Plate I, 5), whilst
an alcoholic solution made alkaline with potash absorbs dark
blue powerfully, and shows two very deep bands between F and
E, and E and D, and one weak one at d. (Plate L, 6.) The
difference between the spectra of alizarin and purpurin is so great
that an admixture of 1 per cent, of the latter can be detected with
facility in the former. The direct detection of small quantities of
alizarin in purpurin is, however, impossible, but, according to

1 For frangulin and frangulic acid, see also Faust, Archiv d. Pharm. clxxxvii.
8, 1869 (Pharm. Journ. and Trans. [3], iii. 1033).

- 'Prakt. Spektralanalyse, ' Nordlingen, Beck, 1877 ; and Ber. d. d. chem.
Ges. x. 157. See also ibid. 175 and 550 (Journ. Chem. Soc. vol. xxxii.).

134 HESINS, BITTER PRINCIPLES, ETC.

Schunk and Romer,1 indirect proof may be obtained by taking
advantage of the unequal affinity of the two substances in alkaline-
solution for atmospheric oxygen. A solution in caustic soda is
exposed to the air until it has become almost colourless and ceases-
to show the spectrum of purpurin after the addition of more
alkali. By acidifying with hydrochloric acid and agitating with
ether, the alizarin can be extracted, redissolved in alcoholic
potash, and tested spectroscopically.

The scale on Plate I. corresponds to that described in § 20. I
shall subsequently come to speak of the spectra of chlorophyll,,
hsematoxylin, and some other colouring matters (partly taken
from Vogel) also figured on the same plate.

Purpurin forms orange-red needles, melting at 253°, and soluble
in boiling water and alcohol, but more freely so in ether, bisul-
phide of carbon, and boiling benzene. Aqueous solutions of alum
dissolve it, forming yellow liquids with green fluorescence ; with
dilute aqueous alkalies purple solutions are obtained ; it dissolves
with difficulty in alcoholic soda, and is precipitated by lime- and
baryta-water.

The erytlirosclerotin, or sclererythrin, isolated by Podwissotzky
and myself2 from ergot is, I think, possibly identical with, or
closely allied to, purpurin.

Alizarin is generally considered to be produced from a glucoside,
ruberytluic acid, and not to occur ready-formed in the madder
plant ; rubery thric acid is possibly itself a product of the decom-
position of rubian. The latter is said to be soluble in hot water
and in alcohol ; from aqueous solution it is not precipitated by
solution of alum or lead salts, but probably it has not yet been
obtained in a state of purity. Boiling solutions of alkalies dis-
solve rubian with production of a red colouration and formation
of alizarin, rubiretin, verantin, rubiadin and sugar. Boiling
dilute acids induce a similar decomposition, whilst with cold
dilute alkali it yields rubianic acid.

Ruberytliric acid is freely soluble in hot water, in alcohol, and
in ether. It crystallizes in yellow silky prisms, and forms blood-
red solutions with alkalies. Basic acetate of lead precipitates it
as a vermilion-red powder. Boiling with dilute acid resolves it

1 Ber. d. d. chem. Ges. x. 175, 1877 (Journ. Chem. Soc. xxxi. 664).

2 Archiv f. exper. Patholog. und Pharmakologie, vi. 154, 1876 (Pharm.
Journ. and Trans. [3], vi. 1001, viii. 106). Sitz-Ber. d. Dorpater Naturf. Ges.,
392, 1877.

§ 148. RHINACANTRIN, ALKANNIN, ETC. 135

into sugar and alizarin. According to Stenhouse, morindin is
identical with ruberythric acid, morindon with alizarin (which is
doubted by Stein), and munjestin with purpurin.

With regard to the constituents of madder that have been here
mentioned, and some others that accompany or can be obtained
from them, I refer in particular to the investigations of Schunk,
Eochleder, Stenhouse and others, for an account of which
Gmelin's * Chemistry ' may be consulted.

For rhamnin, xanthorhamnin, chrysorhamnin, and their allies, see
Fleury and Biswanger,1 Ortlieb, Liebermann, and Hermann.2

Bhinacanthin, discovered by Liborius in Rhinacanthus com-
munis, appears to possess some of the properties common to
anthraquinone-derivatives.3 It occurs in the intercellular spaces
in the root bark, is soluble in ether, alcohol and dilute alkali, but
insoluble in pure and acidulated water. Alkalies produce a deep red
colouration, which is discharged or changed to greenish by acids.

Alkannin is insoluble in water, but yields fine red solutions
with ether, alcohol, bisulphide of carbon, fixed and ethereal oils.
The spectrum is figured on Plate I, 11. Alkannin is uncrys-
tallizable, dissolves in concentrated sulphuric acid (violet), in
alkalies (blue), and in alcoholic ammonia.

Bixin behaves similarly to water, alcohol and ether. It dissolves
in aqueous alkalies also (but the compounds thus produced are
sparingly soluble in alcohol), and is coloured blue by concentrated
sulphuric acid.4

Curcumin5 is also insoluble in water, but is dissolved yellow by
ether and alcohol, brown by alkalies. Boracic acid colours it red,
changing to dark blue on the addition of an alkali. (For its spec-
trum see Plate I., 12.)

For cambogic acid, which is dissolved yellow by concentrated
sulphuric acid, see Johnstone6 and Buchner.7

1 Journ. de Pharm. et de Chim. xxvii. 666 ; Repert. f. Pharm. civ. 54.

2 Bull, de la Soc. de Mulhouse, xxx. 16 ; Ber. d. d. chem. Ges. xi. 1618.
See also Lefort und Stein, Jahresb. f. Pharm. 145, 1867 ; 127, 1868 ; 123,
1869 (Journ. Chem. Soc. xxxvi.).

3 Sitz-Ber. d. Dorpater Naturf. Ges. 277, 1879 (Pharm. Journ. and Trans.
[3], ix. 162).

4 Compare Stein, Chem. Centralblatt, 939, 1867.

8 See Linda und Daube, Journ. f. prakt. Chem. ciii. 474, and New Series,
ii. 86, 1870 (Journ. Chem. Soc. xxiv. 152).

6 Phil. Mag. 281, 1839.

7 Annal. d. Chem. und Pharm. xlv. 72, 1843 (Amer. Journ. Pharm. xv. 129).

136 XESINS, SITTER PRINCIPLES, ETC.

For gronhartin or taigusic acid see Stein and Arnaudson.1
Pipitzahoic add also probably belongs to this group.2
§ 149. Detection of Anthraquinone-derivatives. — To prove that
these substances, or others that have been separated with resins,
or resins themselves, are entitled to be considered as anthracene-
derivatives, they may be heated dry with zinc dust in a glass tube
in the same way as in ultimate analysis (Le., a mixture of zinc
dust with the substance at the end of the tube, followed by a layer
of pure zinc), the products of decomposition being led into a
cooled receiver. 5 Anthracene and methylanthracene should be
specially looked for ; both of them are obtained in the form of
crystalline sublimates. The former melts at 213°, possesses a
blue fluorescence, is insoluble in water, sparingly soluble in
alcohol, but more easily in ether, benzene and bisulphide of
carbon. When dissolved in benzene it forms a compound with
picric acid, which separates out in red crystals. The action of
bichromate of potash and sulphuric acid converts it into anthra-
quinone. If anthracene alone is obtained, a derivative of that
body would be indicated ; methylanthracene alone or together
with anthracene would arouse suspicion of the presence of a
methylanthracene derivative. The latter possesses, like anthra-
cene, a powerful blue fluorescence ; it melts at 200°, forms with
picric acid a compound crystallizing in dark red needles, yields
with bichromate of potash, sulphuric and glacial acetic acids,
anthraquinone-carbonic acid, which is sparingly soluble in excess
of potash and melts at 278°. Methylanthracene is only slightly
soluble in ether, alcohol and glacial acetic acid, but freely in bisul-
phide of carbon and benzene.

§ 150. Hcematoxylin, etc. — Treatment with alkali also reveals
the presence of haematoxylin ; but it must be observed that this
substance can be removed by pure or acidulated water from the
evaporation-residue of the ethereal extract (§ 38).4 With alkalies

1 Journ. f. prakt. Chem. xcix. 1 ; Jahresb. f. Pharm. 165, 1866.

2 Compare Weld, Annal. d. Chem. und Pharm. xcv. 188, 1855 (Amer.
Journ. Pharm. xxx. 446).

3 Compare Liebermann und Graebe, Ber d. d. chem, Ges. i. 49, 104, 1868
(Journ. Chem. Soc. xxv. 139).

4 The extraction of haematoxylin with ether free from alcohol and water is
generally incomplete, as it is somewhat sparingly soluble in that menstruum ; a
part, therefore, will probably be removed on subsequently treating with
alcohol.

§ 150. BRASILLIN, SANTALIN, ETC. 137

hrematoxylin produces a beautiful violet colour ; it reduces alkaline
copper-solution as well as salts of silver and mercury, and cannot
be sublimed.

The best method of extracting hsematoxylin from vegetable
substances (such as logwood) is to macerate first with water con-
taining a little sulphurous acid and then exhaust with ether
saturated with water. (For the spectrum, see Plate I, 7 and 8.)

Bmsillin resembles haematoxylin, and, like it, is soluble in ether,
alcohol and water. Alkalies produce a carmine-red colouration,
which disappears when the liquid is warmed with zinc dust, but
returns on exposure to the air. The spectrum is shown on Plate
I., 9. On boiling with peroxide of lead and water a strong
fluorescence is developed.

Santalin is soluble in ether (yellow), and alcohol (red), but not
in pure water. With dilute potash it yields a violet coloured
solution, from which chloride of barium precipitates a violet
barium-compound. It differs from alizarin in its melting-point
(104°), in not subliming, and in yielding no anthracene. (For
spectrum see Plate I., 10.)

§ 151. Detection and Estimation of Gallic Acid, Catechin, etc. — In
addition to the foregoing substances gallic acid, catechin and
pyrocatechin are extracted by water from the evaporation-residue
of the ethereal extract (§ 38). They are deposited in acicular
crystals on evaporating an aqueous solution over sulphuric acid at
the ordinary temperature, or may be removed by shaking with
ether, or preferably, acetic ether. If in sufficient quantity, gallic
acid or catechin may be purified by re-crystallization from boiling
water, the former being soluble in 3 parts of boiling and about
100 of cold water, the latter in 4 and 16,000 respectively. Heated
between watch-glasses, gallic acid yields a white sublimate of pyro-
gallol, together with black non-volatile melangallic acid. Catechin
yields pyrocatechin. (Of. §§ 38 and 42.) Cone, sulphuric
acid dissolves gallic acid colourless in the cold, but on warming
the liquid becomes wine-red and crimson. The addition of water
now causes the separation of rufigallic acid, which is coloured
transient blue by cone, potash. If only traces of the latter acid
are present they may be extracted, according to Barfoed,1 from the
aqueous liquid by agitation with acetic ether containing spirit,
and the residue obtained on evaporation treated with potash.
1 Barfoed, Lehrb. d. org. qual. Analyse. Lief. 1, 63.

138

EESINS, BITTER PRINCIPLES, ETC.

Under the influence of alkalies gallic acid turns rapidly green,
red and reddish-brown. Like tannic acid, it yields inky mixtures
with ferrous and ferric salts, but is not precipitated by gelatine
from aqueous solution. It reduces nitrate of silver and alkaline-
copper solution. Gallic acid is precipitated by acetate of lead,
and is partially removed from aqueous solution by digestion with
the hydrate of that metal. The precipitates are, however, neither
quite insoluble nor of constant composition, so that they cannot
be recommended as a means of estimating gallic acid except
under certain conditions. If a solution of hydrate of lead in
potash is boiled with very dilute solution of gallic acid, a rose 01
violet colour is developed, which is persistent for some tii
especially in the presence of alcohol (Klunge).

Catechin colours cone, sulphuric acid, on warming, purple,
changing to black. Solutions in aqueous potash, ammonia or
carbonated alkalies gradually absorb oxygen and become rose-red,
scarlet, passing to dark red and finally black. The alkaline solu-
tion produces at first no colouration with ferrous sulphate, but a
green tinge is subsequently developed ; acetate of soda is said to
turn the colourless mixture instantly violet-blue, and cause th<
separation of a bluish-black precipitate. A very small quantity
of ferric chloride colours solutions of catechin green, but ex(
causes decolourization and formation of a brown precipitate.
Like gallic acid, catechin does not precipitate gelatine, and acts
a reducing agent. The lead salt obtained by precipitation is not
suited for the quantitative determination of catechin, as it easili
decomposes (turning red on exposure to the air).

A better method for estimating both catechin and gallic acic
consists in agitating with ether or acetic ether and weighing th(
evaporation-residue, or preferably, titrating it with perman-
ganate of potash. (Of. § 52, VII. ; §§ 53 and 165.)

Pyrocatechin is also easily soluble in alcohol, melts at 112°, am
can be sublimed. Exposed to the air in alkaline solution it ti
green and black ; f erroso-ferric salts colour it dark green,
reduces gold and silver salts and alkaline-copper solution. Wit
acetate of lead a precipitate is formed, which is soluble in acetic
acid ; solution of gelatine is not precipitated.

§ 152. Quercitrin, Quercetin, etc. — Quercitrin and quercetin, if
present in the material under examination, might be partially
extracted with ether (§ 36), by which, however, they are not very

§ 152. QUERCITRIN, QUERCETIN, ETC. 139

easily dissolved. They are both very slightly soluble in cold
water ; quercetin even in hot. They dissolve in the fixed and
volatile alkalies, and in alcohol, crystallizing from the latter
in yellow needles. Ferric chloride colours the alcoholic solu-
tions green (quercetin red, on warming) ; acetate of lead pro-
duces orange-red and brick-red precipitates respectively. Both
quercitrin and quercetin reduce solutions of gold and silver salts,
and also alkaline-copper solution after prolonged boiling. Heat-
ing with mineral acids resolves quercitrin into isodulcite and
quercetin (Lowe contradicts this, and asserts that water alone is
given off). It may be extracted from aqueous solution by agitation
with amylic alcohol.1 It melts at 130° to 133°, and is insoluble
in benzene, petroleum spirit, chloroform, and bisulphide of
carbon.

In close relation to, but not identical with, quercitrin or rutin
stands the violaquercitrin recently isolated by Mandelin2 from
Viola tricolor. It was deposited in yellow acicular crystals on
saturating the aqueous solution with benzene. Boiling with
dilute acids decomposed it with production of glucose, quercetin,
and a third body as yet not further investigated.

A body allied to quercetin appears to occur in the rhizome of
Podophyllum peltatum.3 According to Podwissotzky, the other
important constituents of this drug are podophyllotoxin, which
melts at 115° to 120°, is sparingly soluble in water, soluble in
ether and chloroform, and precipitated from chloroformic solution
by petroleum spirit ; picropodophyllin, which is easily crystallizable,
and soluble in 95 per cent, spirit, ether and chloroform, but
insoluble in milk of lime and ammonia ; and podophyllic acid.

Gentisin is said to require 2,000 parts of cold ether for solution,
and must therefore be looked for in the alcoholic extract. It forms
pale yellow silky needles, which can be partially sublimed without
decomposition, requires 5,000 parts of cold, 3,850 of hot water,
455 of cold and 62-5 of hot absolute alcohol for solution. Ferric

1 Compare Johanson, ' Zur Kenntniss einzelner chemischer Bestandtheile
der Weiden,' etc. Archiv d. Pharm. [3], xiii. 110, 1878 (Pharm. Journ. and
Trans. [3], viii. 69). For Lowe's paper see Zeitschr. f. anal. Chemie, xiv.
233, 1875 (Journ. Chem. Soc. xxix. 108). See also Liebermann and Ham-
burger, Ber. d. d. chem. Ges. xii. 1178, 1879 (Journ. Chem. Soc. xxxvi, 944).

2 Sitz-Ber. d. Dorpater Naturforscher, Ges. 1882, p. 343.

3 Compare Podwissotzky, Archiv f. Pharm. und exper. Pathologic, 29, 1880
(Pharm. Journ. and Trans. [3], xii. 217, 1011).

140 RESINS, SITTER PRINCIPLES, ETC.

salts precipitate it reddish-brown from alcoholic solution. Fused
with potash it decomposes, yielding acetic acid, phloroglucin and
gentisic acid. The latter is isomeric with protocatechuic acid (§ 42),
and is coloured deep blue by ferric chloride. An alkaline solution
of gentisic acid becomes red on exposure to the air ; when heated
it yields hydroquinone, melting at 1690.1

For thujin, see Rochleder and Kawalier ;2 for rutin (insoluble in
ether), and robinin, Zwenger and Dronke ;3 for luteolin, Molden-
hauer,4 Schiitzenberger, Paraf and Rochleder.5

§ 153. Jalapin and Allied Substances. — To the group of substances
that are soluble in ether, and can be removed by dilute alkali,
but not by pure water, from the evaporation-residue of the
ethereal extract, there belong further some glucosidal resins
(§ 58), of which the jalapin of Ipomcea orizabensis may be taken
as a representative.

Jalapin is readily dissolved by alcohol, and in alcoholic solution
is resolved by hydrochloric acid into sugar and jalapinol; the
latter is soluble in ether, but only sparingly soluble in water.
The action of aqueous solution of soda converts jalapin into
jalapic acid ; the latter, after liberation with a strong acid, is
soluble in water, but only sparingly soluble in ether.

Jalapinol appears to occur ready-formed in scammony, and
possibly in scammony-root also.

Tampicin of Tampico-jalap resembles jalapin in most of its pro-
perties, but differs in composition.6 The same may be said of

1 Compare Hlasiwetz and Habermann, Annal. der Chem. und Pharm. clxxv.
62 ; Ber. d. d. chem. Ges. viii. 684 (Journ. Chem. Soc. xxviii. 572).
actual gentian-bitter is not identical with gentisin. The former is easily
soluble in water, is not thrown down by neutral acetate of lead, but precipi-
tated by ammoniacal acetate and liberated from the precipitate by sulphurette
hydrogen. It can be extracted with difficulty by agitation with benzene, but
with ease by chloroform ; ferric chloride does not precipitate it. It is sparingl}
soluble in ether, and is said to dissolve in cone, sulphuric acid with red coloura-
tion, and to be decomposed by dilute sulphuric acid with production of sugar.
(Compare Kromayer, loc. cit.).

2 Chem. Centralblatt, 449, 1858.

3 Ibid. 766, 1862. Annal. d. Chem. und Pharm. Supplement, i. 257
(Amer. Journ. Pharm. xxxv. 32).

4 Annal. d. Chem. und Pharm. c. 180, 1856.

5 Comptes Rendus, lii. 92, 1861 ; Journ. f. prakt. Chemie, xcix. 433,
1867.

6 Compare Spirgatis, N. Eepert. f. Pharm. xix. 452, 1870; Kohler und
Zwicke, N. Jahrb. f. Pharm. xxxii. 1, 1869 (Pharm. Journ. and Trans. [3],
i. 444).

§ 154. ESTIMATION OF SANTONIN. 141

the convolmdln of true jalap, which is distinguished by its insolu-
bility in ether, and of turpethin^ which is insoluble in ether, but
differs in composition from convolvulin.

All these glucosidal resins dissolve in cone, sulphuric acid with
purple colour.

§ 154. Estimation of Santonin. — The following method maybe
adopted for the quantitative estimation of santonin (§ 45) in
worm-seed :3

15 to 20 grams of the material are digested on a water-bath for
2 hours with 15 to 20 cc. of a 10 per cent, caustic soda solution
diluted with about 200 cc. of water, filtered and washed. The
nitrate and washings are concentrated to 30 or 40 cc., cooled,
neutralized with hydrochloric acid, and at once filtered. The pre-
cipitate is washed first with 15 to 20 cc. of water, and then with
an 8 per cent, soda solution, and any crystals of santonin
that may thus be separated subsequently added to the principal
portion. The filtrate from the hydrochloric acid precipitate is
acidified and shaken with 3 successive portions of 15 to 20 cc. of
chloroform. The chloroformic solutions are washed with water
and evaporated to dryness ; the residue is dissolved in the smallest
possible quantity of soda, filtered if necessary (washing the in-
soluble portion with a very little water), and acidified with
hydrochloric acid. After standing for 2 or 3 days in a cool
place the santonin is filtered off, washed with 10 to 15 cc. of
8 per cent, solution of soda, dried at 110°, and weighed. A cor-
rection must be made of 0-002 gram for every 10 cc. of mother-
liquor, and 0-003 gram for every 10 cc. of washings.

Santonin can also be extracted by boiling with milk of lime.
15 to 20 grams of worm-seed are digested with 200 cc. of milk of
lime diluted with 400 cc. of water on the water-bath for 6 hours,
boiled for half an hour and filtered. The residue is again boiled
with 10 cc. of milk of lime diluted with 200 cc. of water. The
filtered decoctions and washings are evaporated to about 30 cc.,
excess of hydrochloric acid added, and at once filtered (the preci-
pitate being treated with soda as before). The filtrate must
stand for 5 or 6 days in a cool place, when the santonin may be
collected and washed with soda-solution. The small amount that

1 N. Repert. f. Pharm. xiii. 97, 1864 (Amer. Journ. Pharm. xxxi. 374).

2 Compare Archiv d. Pharin. [3], xiii. 306, 1878 (Amer. Journ. Pharm. 1.
296).

142 RESINS, BITTER PRINCIPLES, ETC.

remains dissolved in the mother-liquor and washings may be
removed by shaking with chloroform.

Santonin is almost insoluble in cold water, but is dissolved by
ether, alkalies and boiling alcohol. It melts at 169°, turns yellow
on exposure to light, produces no colouration when dissolved in
cone, sulphuric acid, but colours alcoholic potash transiently
carmine. If a solution of santonin in sulphuric acid is heated to
150°, and a drop of a dilute solution of ferric chloride subse-
quently added, the mixture assumes a red tinge, gradually chang-
ing to violet.

§ 155. Picfrotoxin, etc. — Amongst other substances to be looked
for in the ethereal extract the following may be mentioned :

Picrotoxin. — Soluble in 150 parts of cold, and 25 of boiling
water, as well as in alcohol, chloroform, and amylic alcohol.
From aqueous solution (§ 55) it may be extracted by the last two
solvents, and also by ether, but not by benzene.1 It crystallizes
with facility from water and alcohol in four-sided prisms, reduces
alkaline copper solution, and dissolves yellow in cone, sulphuric
acid. If dry picrotoxin is mixed with 6 parts of nitrate of potash,
and sufficient cone, sulphuric acid to form a pasty mass, a brick-
red colour is developed on adding a solution of soda (1 to 3) in
excess. The reaction succeeds better if the picrotoxin is moistened
with nitric acid, dried on the water-bath, mixed with a very
little sulphuric acid, and then with solution of soda.

Digitalin. — According to Schmiedeberg,2 this glucoside is in-
soluble in water and dilute soda, but soluble in warm dilute acetic
acid. Alcohol, alone or mixed with chloroform, dissolves it easily,
but in pure ether or chloroform it is more sparingly soluble. It
is a colourless crystalline glucoside, yielding glucose and digita-
liresin by decomposition with hydrochloric acid in alcoholic soli
tion. It dissolves yellowish green in boiling hydrochloric acid,
brown in sulphuric acid, the latter solution becoming violet on
the addition of bromine water (§ 55).

Digitoxin accompanies digitalin in foxglove ; it crystallizes in
pearly plates and needles, is not very soluble in ether, am
insoluble in water and benzene. Chloroform and hot alcohol

1 See also Gaabe, 'Unters iiber einige Derivate des Picrotoxins.' Diss.
Dorpat, 1872.

2 Archiv f. exper. Patholog. und Pharm. iii. 16, 1874 (Pharm. Journ. and
Trans. [3], v. 741).

§ 155. DIGITALE1N, DIGITONIN, ETC. 143

dissolve it freely. Boiled with dilute acids in alcoholic solution,
it is transformed into toxiresin (soluble in ether) without the
simultaneous production of sugar. With hydrochloric acid it
gives a reaction resembling that of digitalin, but is not coloured
violet by sulphuric acid and bromine water. Digitalin, digitoxin
and toxiresin are all characterized by very energetic physiological
action that may be of use in their identification.1

I take this opportunity of referring to three other constituents
of foxglove, which, however, are insoluble in ether. They are
the following :

Digitaldn. — This substance agrees in its physiological action
with digitalin and digitoxin, but differs from them in its
solubility in water and cold absolute alcohol. It is sparingly
soluble in chloroform, and is precipitated from alcoholic solution
by the addition of a large quantity of ether. Boiling with dilute
acids decomposes it into glucose and digitaliresin. Sulphuric acid
and bromine produce the same colouration as with digitalin.
Tannic acid and basic acetate of lead precipitate it from aqueous
solution (§ 55).

Digitonin is, as already observed (§ 79), allied to saponin ; it is
amorphous and soluble in water, to which it imparts the property
of frothing. Ether precipitates digitonin from alcoholic solution
more easily than it does digitalein. Baryta-water, tannic acid,
and basic acetate of lead precipitate it from its concentrated
aqueous solution. Boiling with hydrochloric acid resolves
digitonin into glucose, digitoresin and digitonein, with a gradual
development of a garnet-red colouration. Cone, sulphuric acid
colours it brownish red, which is not changed to reddish violet
by bromine.

Digitin is a resinous substance that can be obtained in warty
crystals from alcoholic solution. It is insoluble in water, ether,
benzene and chloroform, and possesses no marked physiological
action.

For coriamyrtin compare Kiban.2

For ericolin, which is decomposed by hot dilute sulphuric acid,
yielding glucose and ericinol, see Rochleder and Schwartz.3

1 Compare my ' Ermittelung d. Gifte,' 2nd ed. 272 et seq.

2 Bull, de la Soc. chim. de Paris, vi. 87, 1864 ; vii. 79. 1865 (Amer. Journ.
Phann. xxxvi. 114).

3 Annal. d. Chem. und Pharm. Ixxxiv. 366, 1852, and Chem. Centralblatt,
61, 1853. Compare also my 'Ermittelung d. Gifte,' 2nd ed., 300 et seq.

144 RESINS, BITTER PRINCIPLES, ETC.

Ericinol is characterized by its odour. (Compare also §§ 55 and
167.)

Vanillin (cf. § 167), the aromatic constituent of vanilla, is
very sparingly soluble in cold petroleum spirit, but might be
partially carried into solution in the presence of fixed or ethereal
oil ; as a rule, however, it may be found in the ethereal extract.
It is colourless, crystalline, possesses the pleasant odour of vanilla,
and is soluble in 183 parts of water (at 18°), in 4-4 parts of
alcohol (specific gravity 0-803), and in 6 '24 parts of ether. It
melts at 82°, and is soluble in dilute soda ; ferric chloride colours
the aqueou's solution dark bluish-violet. Being an aldehyde of
methylprotocatechuic acid, it combines with acid sulphites
(§ 33), and it is upon this property of vanillin that the follow-
ing (Thiemann and Haarmann's) method of estimation is
based i1

The ethereal extract of about 30 grams of vanilla is evaporated to
150 cc., and thoroughly shaken for 10 to 20 minutes with a mix-
ture of water and saturated aqueous solution of bisulphite of soda.
The ethereal solution is separated and again shaken with 100 cc.
of the bisulphite mixture. The aqueous solutions are united and
washed with pure ether to remove impurities. To every 100 cc.
there are then gradually added 150 cc. of a mixture of 3 vols.
of pure sulphuric acid with 5 vols. of water. The sulphurous
acid evolved is received into solution of soda, the remainder being
expelled by passing a current of steam through the liquid. After
cooling, the vanillin, which has been liberated, is extracted by
shaking with 3 to 4 successive portions of ether, and can be
weighed after evaporating the ethereal solution.

Ostruthiin, which resembles vanillin in being sparingly soluble
in petroleum spirit,2 is not precipitated by that liquid from
ethereal solution. It crystallizes in delicate, pale yellow needles,
melting at 91° ; is insoluble in cold water, sparingly soluble in
boiling water and benzene, freely in alcohol and in ether. The
alcoholic solution possesses a feeble blue fluorescence, which is
increased by the addition of water. With aqueous alkalies it forms
strongly fluorescent solutions, from which carbonic acid precipi-
tates the ostruthiin unaltered. It gives no characteristic reactions

1 Zeitschr. f. anal. Chemie, xv. 350, 1875 (Journ. Chem. Soc. xxix. 112).

2 Compare Gorup-Besanez, Annal. d. Chem. und Pharm. clxxxiii. 321, 1876
(Pharm. Journ. and Trans. [3], vii. 984).

§ 155. PEUCEDANIN, OREOSELON, ETC. 145

with metallic salts, nor does it yield angelic acid or allied sub-
stances when acted upon by alkalies.

Peucedanin1 is allied to, but not identical with, ostruthiin. It
yields no valerianic or angelic acid, but is decomposed by the
action of acids into oreoselon and methyl-compounds ; it is, in
fact, dimethyl-oreoselon. Peucedanin melts at 76°, is colourless,
crystalline, insoluble in cold water, but freely soluble in alcohol
and ether.

Oreoselon can be obtained from peucedanin ; it is almost insoluble
in cold water, but soluble in alcohol, ether and benzene. Bisul-
phide of carbon, ammonia and dilute alkalies dissolve it only when
warmed, and the latter solution reduces alkaline copper-salts.
The alcoholic solution is not altered by ferric chloride. A blue
fluorescent solution is yielded by cone, sulphuric acid, but not by
alkalies. Fused with an alkali, it yields acetic acid and resorcin

<§ 42).

AtJiamanthin.2 — The statement that this substance is divaleryl-
oreoselon requires further investigation. It crystallizes in colour-
less needles melting at 79°, is insoluble in water, but dissolves in
diluted alcohol and in ether.

Laserpitin* forms colourless prisms, melting at 114°, and is
sparingly soluble in water and alkalies, but freely in alcohol, ether,
chloroform, benzene, and bisulphide of carbon. Cone, sulphuric
and fuming nitric acid dissolve it with red colouration ; boiling
with alcoholic potash is said to decompose it into angelic acid and
laserol.

Cubebin can also be obtained in colourless crystals, melting at
120°, difficultly soluble in cold, more easily in warm water, and
soluble in 26 parts of ether, 76 of cold and 10 of boiling alcohol.
It can be removed from aqueous solution by shaking with benzene
or chloroform. Cone, sulphuric acid is coloured red by cubebin.
Aqueous alkalies do not dissolve it.4 (Cf. § 55.)

Betul'ui is likewise tolerably freely soluble in ether and boiling

1 Compare Hlasiwetz und Weidel, Annal d. Chem. und Pharm. clxxiv. 67 ;
Heut, ibid, clxxvi. 70 (Journ. Chem. Soc. xxviii. 258, 772).

2 Compare Schnedermann und Winkler, Annal. d. Chem. und Pharm. li.
:n5, 1844 ; Hlasiwetz und Weidel, ibid, clxxiv. 67.

3 Compare Feldmann, 'Ueber das Laserpitin.' Diss. Gottingen.

4 For an analysis of cubebin compare Schmidt, Jahresb. f. Pharm. 51, 1870
(Fharm. Journ. and Trans. [3], ii. 270). For cubebin see Weidel, Jahresb. f.
rharm. 68, 1877 (Amer. Journ. Pharm. 1. 257).

10

146

EESINS, SITTER PRINCIPLES, ETC.

alcohol, but insoluble in water and petroleum spirit. It dissolves
in cone, sulphuric acid, from which it can be precipitated by
water. Betulin forms white crystals, which melt at about 200°,
and are not attacked by aqueous alkalies.1

Anacardic acid can be obtained as a white crystalline mass,
melting at 26°, freely soluble in alcohol and ether, and dissolving
in cone, sulphuric acid with blood-red colouration.2

Cardol is a colourless oil accompanying anacardic acid in the
cashew nut. It is soluble in alcohol and in ether, but not
water, and possesses powerful vesicant properties (not shared
anacardic acid). It can be removed from suspension in water by
agitation with chloroform. Contact with dilute potash for a short
time does not result in the loss of the vesicant property of cardol,
as is the case when the alkali is concentrated and the action pro-
longed. The tough mass thus produced becomes red on exposure
to the air, and gives with basic acetate of lead a precipitate that
shows the same peculiarity.

§ 156. Absinthiin, etc. — The following bitter principles are also
soluble in ether : dbsinthiin8 (dissolves in cone, sulphuric acid with
brown colour, passing to violet. See also § 55), adansonmf
alchornin,5 anthemic acid,6 antirin,7 aristolochia-yellow,8 arnicin9
asclepiadin1® beberic acid,11 caikedrin,12 caryophyllinlz (coloured blood-
red by concentrated sulphuric acid, cf. § 55), cascarillin

1 Compare Hausmann, ' Beitrage zur Kenntniss des Betulins,' Gb'ttinc
1878.

2 See Stadeler, Annal d. Chem. und Pharm. Ixiii. 137, 1847 (Amer. Joui
Pharm. xx. 139).

. 3 Compare Kromayer, Archiv d. Pharm. cviii. 129, 1868.

4 Compare Walz, Jahrb. f. prakt. Pharm. xxiv. 100, 242; xxvii. 1
Wittstein, Vierteljahressch. f. prakt. Pharm. iv. 41.

5 Compare Frenzel, Archiv d. Pharm. xxiii. 173, 1829 ; Biltz, ibid. xii. 4(
1826.

e Compare Jahresb. f. Pharm. 51, 1867 ; 46, 1871.

7 Compare Walz, Jahrb. f. prakt. Pharm. xxvii. 74, 129 (Amer. Jour
Pharm. xxxv. 295).

3 Compare Frickinger, Eepert f. Pharm. [3], vii. 12.

9 Compare Walz, N. Jahrb. f. Pharm. xiii. 175 ; xiv. 79 ; xv. 329, 18(
1861 (Amer. Journ. Pharm. xxxiii. 451).

10 Compare List, Annal. d. Chem. und Pharm. Ixix. 125, 1849.

11 Compare Maclagan, Annal. d. Chem. und Pharm. xlviii. 106, 1843 ; Iv.
105, 1845 (Amer. Journ. Pharm. xix. 113).

12 Compare Caventou, N. Jahrb. f. Pharm. xvi. 335, 1861.

13 Compare Bonastre, Jahrb. f. Pharm. xi. 103 ; and Jahn, Annal. d. Cl
und Pharm. xix. 333, 1837.

14 Compare Trommsdorf, N. Journ. f. Pharm. xxvi. 2, 142 ; and
N. Jahrb. f. Pharm. viii. 95, 1857.

§ 156. ABSINTHIIN, ETC. 147

(the same), chimaphilin,1 chiratin2 and opJielic acid, cicutin,5
columbin.*

Coto'in5 crystallizes in quadratic prisms, is sparingly soluble in
cold water, freely in alcohol, ether and chloroform. It melts at
130°. Ferric chloride colours the alcoholic solution dark brown.
Warming with nitric acid colours cotoin blood-red, paracotdin
brown. The latter melts at 152° (uncorrected). A description of
leucotin, oxyleucotin and hydrocotoin will be found in the re-
searches on cotoin and paracotoin above referred to.

Elaterin® is sparingly soluble in ether, and is coloured yellow
by cone, sulphuric acid. 1 to 2 drops of carbolic acid produce a
red tinge, which changes to crimson on the addition of the same
quantity of cone, sulphuric acid. (See also § 55.)

I may mention further, erythrocentaurin,7 eupatorin,8 guacinf
hop-bitter. IQ (To isolate the hop-bitter Isleib exhausts hops with
cold water, absorbs the bitter principle with charcoal, extracts it
from the same with 90 per cent, alcohol, distils, and, after
separating the resin, skakes the resulting liquid with ether. He
confirms the statement that hop-bitter is not a glucoside, but, on
boiling with dilute acids, combines with a molecule of water
yielding sparingly soluble lupuliretin. Part of the hop-resin may
be removed from aqueous solution by shaking with petroleum

1 Compare Fairbank, Vierteljahresschr. f. prakt. Pharm. ix. 582, 1860
(Amer. Journ. Pharm. xxxii. 256).

2 Compare Kemp, Pharm. Journ. and Trans. [3], 1, 251, 1870 ; Hb'hn,
Archiv d. Pharm. clxxxix. 229, 1869.

3 Compare Wikszemski, ' Em Beitr. z. Kenntniss der giftigen Wirkung d.
Wasserschierling.' Diss. Dorpat, 1875, and Jahresb. f. Pharm. 493, 1875.

4 Compare Boedecker, Annal. d. Chem. und Pharm. Ixix. 37, 1849 (Amer.
Journ. Pharm. xx. 324).

5 Compare Hesse, und Jobst. Neues Eepert. f. Pharm. xxv. 23, 1876 ; Ber.
d. d. Chem. Ges. x. 149, 1877 ; Annal. d. Chem. und Pharm. cxcix. 17, 1879
(Pharm. Journ. Trans. [3], vi. 764 ; vii. 495, 1019 ; x. 521, 541).

6 Compare Zwenger, Annal. d. Chem. und Pharm. xliii. 35,9, 1842 ; Walz,
N. Jahrb. f. Pharm. xi. 21, 178, 1859 j Kohler, N. Eepert. f. Pharm. xviii.
577, 1869.

7 Compare M&iu, Jahresb. f. Pharm. 70, 1866 ; 92, 1870 ; 56, 1871 (Amer.
Journ. Pharm. xxxviii. 303).

8 Compare Righini, Journ. f. Pharm. xiv. 623.

9 Compare Pettenkofer, Repert. f. Pharm. Ixxxvi. 311; Faurd, Jahrb. f.
Pharm. xxii. 291.

10 Compare Lermer, Vierteljahresschr. f. prakt. Pharm. xii. 504, 1863 ;
Bissell, Amer. Journ. Pharm. xlix. 582, 1877 ; Griessmayer, Ber. d. d. Chem.
Ges. xi. 292, 1878 (Journ. Chem. Soc. xxxiv. 449) ; Isleib, Archiv d. Pharm.
[3], xvi. 345, 1880 (Journ. Chem. Soc. xl. 101) ; Cecil, Zeitschr. f. anal. Chem.
xx. 180, 1881 (Journ. Chem. Soc. xl. 946).

10—2

148 RESINS, BITTER PRINCIPLES, ETC.

spirit. Griessmayer has availed himself of this property of hoj
resin in the examination of beer. Cf. § 55.) Other bitter prin-
ciples are hurin,1 jervasic acid? jumpering liriodendrinf lycopinf
marrubinf mangostin,7 masopin8 and meconin.9 The last-named is
soluble in hot water, and can be extracted fronTaqueous solution
after acidification with sulphuric acid, by shaking with benzene,
chloroform, or amylic alcohol. With benzene it can be obtained
fairly pure, and can be detected by cone, sulphuric acid, in which
it dissolves without at first producing any colouration ; but the
solution gradually assumes a greenish, and in the course of twenty-
four hours a reddish tinge. If the liquid is then warmed, the colour
changes to emerald-green, blue and violet, and becomes finally red.

Meconin is accompanied in opium by meconic add, which is
sparingly soluble in water and ether, but more easily in alcohol.
Boiling with water or dilute acids decomposes meconic acid ; with
ferric chloride it strikes a blood-red colour, which is not discharged
by a little hydrochloric aci or chloride of gold. It can be
removed from aqueous solution by shaking with amylic alcohol.
Meconate of calcium is soluble, but the magnesium salt only
sparingly so. Chelidonic acid from Chelidonium majus is sparingly
soluble both in cold water and in alcohol.10

There may be further mentioned here, methysticin11 (which is
slightly soluble in cold ether and dissolves in pure cone, sulphuric
acid with fine reddish-violet, in commercial with blood-red coloura-
tion), Jcawa'in,12 narthecin,13 nucinu (coloured purple by alkalies),

1 Compare Boussingault and Rivero, Annal. de Chim. et de Phys. xxviii. 430
(Amer. Journ. Pharxn. ii. 346).

2 Compare Weppen, Jahresb. f. Pharm. 31, 1872 (Journ. Chem. Soc. xxvi.
906).

3 Compare Steer, Wiener Acad. Anz. B. xxi. 383.

4 Compare Emmet, Repert. f. Pharm. Ixxv. 88 (Amer. Journ. Pharm. iii. 5).

5 Compare Geiger, Repert. f. Pharm. xv. 11.

6 Compare Kromayer, Archiv d. Pharm. cviii. 257, 1862.

7 Compare W. Schmidt, Annal. d. Chem. und Pharm. xciii. 83, 1854 (.
Journ. Pharm. xxvii. 331).

8 Compare Genth, Annal. d. Chem. und Pharm. xlvi. 126, 1843.

9 Compare Pelletier, Anr-al. d. Chem. und Pharm. Ixxxvi. 190, 1853, and
Anderson, xcviii. 44, 1856. See also my 'Ermittel. d. Gifte,' 2nd ed., 238.

10 See Lerch, Chem. Centralblatt, 449, 1846.

11 Compare Nolting and Kopp, Monit. scientif. [3], iv. 920, 1874 (Pharm.
Journ. Trans. [3], vii. 149).

12 Ibid.

33 Compare Walz, N. Jahrb. f. Pharm. xiv. 345, 1861.
14 Compare Vogel and Reinschauer, N. Repert. f. Pharm. v. 106 (1856) ;
vii. 1 (1858).

§ 157. LICHEN ACIDS. 149

plumlagin1 (coloured cherry-red by small quantities of alkalies),
polygonic acid,2 quassin3 (which is soluble in water, can be removed
by shaking with benzene or chloroform. See also § 55), rottterin*
sicopirin,5 tanacetin,6 tanghinin,7 taraxacin,8 xylosteinf xanthosclerotin,
or sderoxanthin.™

§ 157. Lichen Acids and allied Substances. — Amongst the consti-
tuents of plants that are soluble in ether a number occurring in
lichens may finally be mentioned here. Some of them possess
the characters of acids, as, for instance :

Roccellic acid, which is itself insoluble in water, but forms soluble
alkaline salts. It can be detected in the gonidia by alkanna.11

Others are characterized by yielding beautifully coloured com-
pounds when acted upon by alkalies, ferric chloride or chlorinated
lime, properties that would indicate some relation to orcin and
allied bodies. Others, again, possess the chemical characters of
ethereal salts, being resolved by alkalies into stronger acids and
alcohols. To the former group belong the following :

Lecanoric acid (diorsellic acid), which is coloured deep red by
chlorinated lime (avoiding an excess), and is decomposed at 153°
into orcin and carbonic acid.12

Orsellic acid, which undergoes a similar decomposition at 176°,

1 Compare Dulong, Jahrb. f. Pharm. xiv. 441.

2 Compare Rademacker.

3 Compare Wiggers, Annal. d. Chem. und Pharm. xxi. 40, 1837; Gold-
schmidt und Weidel, Ber. d. Wiener Akad. Ixxiv. 389, 1877 (Journ. Chem.
Soc. xxxiv. 80). See also my 'Ermittelung d. Gifte,' 2nd ed., 300 et. seq. ;
and Jahresb. f. Pharm. 619, 1878. Also Christensen, Archiv d. Pharm. xvii.
481, 1882.

4 Compare Anderson, Chem. Centralblatt, 372, 1855 (Amer. Journ. Pharm.
xxxii. 325) ; Groves, Jahresb. f. Pharm. 161, 1873 (Pharm. Journ. Trans. [3],
iii. 228).

5 Compare Peckolt, Zeitschr. d. Oesterr. Apotheker-Ver. 289, 1876 (Pharm.
Journ. Trans. [3], vii. 69).

6 Compare Leroy, Journ. de Chim. ined. xxi. 357 ; Leppig, ' Chem. Unters.
d. Tanacetum vulgare,' Diss Dorpat, 1882.

7 Compare Henry, Journ. de Pharm. x. 52 (Amer. Journ. Pharm. viii. 102).

8 Compare Kromayer, 'Die Bitterstoff e, ' 97 ; and Polex, Archiv d. Pharm.
xix. 50, 1840.

a Compare Hiibschmann, Pharm. Vierteljahresschr. v. 197 ; and Enz, ibid.
196, 1856.

10 Compare Dragendorff and Podwissotzki, loc. clt.

11 Compare Schunck, Annal. d. Chem. und Pharm. Ixi. 66, 78 ; also Hesse,
cxvii. 332, 1861 (Journ. Chem. Soc. iii. 153).

12 Schunck, Annal. d. Chem. und Pharm, xli. 157, 1842 (Journ. Chem. Soc.
i. 71) ; liv. 261, 1845 ; Ixi. 64, 1847 ; Stenhouse, ibid. Ixviii. 57, 1848 ; cxxv.
353, 1863 (Journ. Chem. Soc. xx. 221) ; Hesse, cxxxix. 22, 1866.

150

RESINS, BITTER PRINCIPLES, ETC.

and with alkaline solutions at a temperature as low as the boiling-
point.1 Both this and the foregoing acid form salts of ethyl when
boiled with alcohol.

Gyrophoric acid, which is sparingly soluble in ether, yields 01
on decomposition with alkali, and turns red on exposure to ai
moniacal air.2

Parellic acid, which is only slowly coloured under the same
conditions.3

Ceratophyttin, which strikes a violet colour with ferric chloride
and blood-red with chlorinated lime.4

Patellaric acid, which, in alkaline solution, turns red when ex-
posed to the air. Ferric chloride colours it blue ; chlorinat
lime, blood-red.5

Evernic add yields orcin by dry distillation, is coloured dark-
red by ammoniacal air, but only yellow by chlorinated lime.6

Everninic add (oxyusnetinic acid ?) is also coloured yellow bj
chlorinated lime, but does not change when exposed to ammonij
cal air.

Usnic acid behaves in a similar manner, but an alkaline solution
turns red on exposure to air, and the acid itself yields betaorcin
by dry distillation.7

Carbusnic acid8 (is sparingly soluble in ether) gives no colour
reactions.

Vulpinw add (chrysopicrin), which is more easily soluble in
bisulphide of carbon and chloroform than in ether, is obtainable
in yellow crystals and forms yellow salts with alkalies. Boiling
with baryta-water resolves it into alphatoluic acid, oxalic acid,
and methyl-alcohol.9 It may therefore be placed in the group of

1 Schunck, Annal. d. Chem. und Pharm. xli. 157, 1842 (Journ. Chem. Soc.
i. 71) ; liv. 261, 1845 ; Ixi. 64, 1847 ; Stenhouse, ibid. Ixviii. 57, 1848; cxxv.
353, 1863 (Journ. Chem. Soc. xx. 221) ; Hesse, cxxxix. 22, 1866.

2 Compare Stenhouse, ibid. Ixx. 218, 1849.

3 Compare Schunck, ibid. liv. 274, 1845 ; Strecker, Ixviii. 114, 1848.

4 Compare Hesse, ibid. cxix. 365, 1861,

5 Compare Weigelt, Journ. f. prakt. Chem. cvi. 28, 1869.

6 Compare Stenhouse, ibid. Ixviii. 86, 1848 ; Hesse, ibid, xlvii. 297, 1861.

7 Compare Knop, Annal. d. Chem. und Pharm. xlix. 103, 1843 ; Kochleder
and Held, ibid, xlviii. 1, 1843 ; Stenhouse, ibid. Ixviii. 97, 114. Knop and
Schnedermann, Journ. f. prakt. Chem. xxxvii. 363, 1843 ; Hesse, Annal. d.
Chem. und Pharm. cxvii. 343, 1861.

8 See Hesse, ibid, cxxxvii. 241, 1866 ; Ber. d. d. chem. Ges. x. 1324, 187<
(Journ. Chem. Soc. xxxii. 896).

9 Stein, Chem. Centralblatt, 556, 1864 ; 432, 1865. See also Spiegel, Ber.
d. d. chem. Ges. xiii. 1629, 1880.

§ 157. LICHEN ACIDS. 151

ethereal salts previously mentioned. The same is the case with
ert/fhric add (sparingly soluble in ether), which is regarded as
diorsellinate of erythrite,1 picroerytlirin (orsellinate of erythrite),
and betaerythric acid2 (orsellinate of betapicroerythrin).

For picrolichenin compare Alms, Stenhouse, and Groves ;3 for

:-lc and liclienostearic acid, Schnedermann and Knop ;4 for

rcr'tol'iti'in, Robiquet;5 stictic acid, Schnedermann and Knop ;6

lobaric acid, Knop;7 atranoric acid (hydrocarbo-usnic acid?),

, snrdidin, Paterno;8 calycin, Hesse.9

Microscopical examination shows that the majority of these
acids adhere in the form of minute granules to the exterior of the
hyphae, in heteromerous lichens almost exclusively in the cortical
portion of the upper surface, or, in old specimens, on the margin
of the thallus (Physicia parietina).10

To test for a lichen-acid yielding orcin as a product of decom-
position, the substance under examination, or part of the lichen
itself, may be heated with dilute potash, chloroform added, and
the warming continued for some time in the water-bath. If such
an acid is present, homofluorescin will be produced, and the
solution will appear reddish-yellow by transmitted, and show a
fine yellowish-green fluorescence by reflected light. Usnic acid is
said not to give this reaction, which is yielded by lecanoric,
erythric and evernic acid (by the last-named after continued
boiling with milk of lime).

Erythric and lecanoric acid are extracted from the lichen by
digestion with ammonia, and are precipitated by acetic acid. On
warming, erythric acid passes into solution, whilst lecanoric acid
remains undissolved.

1 Compare Heeren, Schweiz. Journ. lix. 313 ; also Schunck, Stenhouse,
Strecker, Hesse, already quoted.

2 See Menschutkin, Bullet, de la Soc. chim. [2], ii. 424, 1864. Lamparter,
Annal. d. Chem. und Pharm. cxxxiv. 243, 1865.

3 Annal. d. Chem. und Pharm. i. 61, 1832 (Amer. Journ. Pharm. xvi. 262) ;
ibid, clxxxv. 14, 1877 (Proc. Hoy. Soc. Ix. 68).

4 Annal. d. chem. und Pharm. Iv. 144, 159, 1845.

5 Annal. de chim. et de Phys. xlii. 236.
0 Jahresb. f. Pharm. 76, 1845.

7 Chem. Centralblatt, 173, 1872 (Journ. Chem. Soc. xxv. 639).

8 Ber. d. d. chem. Ges. x. 1100 and 1382, 1877 (Journ. Chem. Soc. xxxi.
89 ; xxxii. 270).

9 Ber. d. d. chem. Ges. xiii. 1816, 1880 (Pharm. Journ. Trans. [3], xi. 471).

10 Compare Schwartz in Cohn's ' Beitrage zur Biologic d. Pflanzen,' iii.
Part II. and Archiv d. Pharm. [3], xix. 124, 1881.

152 RESINS, BITTER PRINCIPLES, ETC.

Usnic acid, which occurs in yellow crystals, yields a colourless
ammonium salt.

§ 158. Orcin and Betaorcin. Estimation of Orcin. — Orcin and beta-
orcin, which have already been mentioned as products of the
decomposition of certain constituents of lichens, and which some-
times occur ready formed in plants, can be obtained in colourless
acicular crystals soluble in water, alcohol, and ether. Exposure
to light colours them reddish; alkalies, chlorinated lime and ferric
chloride, violet. By the action of ammonia and air orcin yields a
blue colouring matter, whilst, under the same conditions, beta-
orcin gradually turns red. Orcin melts at 58°, betaorcin at a
temperature above 109°.

Reymann estimates orcin in lichens by titrating with bromine-
water,1 by which monobromorcin is first produced and subse-
quently converted into tribromorcin. To the solution of orcin
in a stoppered bottle titrated bromine-water is added till the
precipitate has assumed a yellowish colour and excess of bromine
is present, which is then estimated by iodide of potassium and
hyposulphite of soda. The amount of orcin present is calculated
from the equations :

C7H802 + Br2 = HBr + C7H7Br02
and

C7H7Br02 + 2Br2 = 2HBr + C7H5Br302.

TANNIC ACIDS.

§ 159. Constitution. — In estimating tannic acids an error has
generally been committed in overlooking too completely the
chemical differences existing between the various substances that
have received this name. It has usually been considered sufficient
to determine quantitatively the value of a reagent in terms of
gallotannic acid, the tannin most easily procurable, and to apply
the results thus obtained to the estimation of other tannins.
This would be admissible under the assumption that all tannins
possessed approximately identical equivalent weights and pro-
duced nearly identical chemical effects. But it has already been
shown in § 52 that such is not the case. It will be sufficient
here to repeat that tannins exist which do not allow of com-
parisons with one another, even with regard to their constitution.
At present many tannic acids may be assumed to be glucosides,

1 Ber. d. d. chem. Ges. viii. 790, 1875 (Journ. Chem. Soc. xxvii. 1293).

§ 160. GLUCOSIDAL NATURE OF TANNINS. 153

splitting up under the influence of dilute acids into glucose and
some second substance, but of a number it must be denied that
they possess any such glucosidal characters.

§ 160. Glucosidal nature. — In enumerating the characters of a
newly-discovered tannic acid, it is, therefore, important to state
whether it has been found to be a glucoside or not (§ 61). The
examination may be made by heating weighed quantities of the
tannin with 1 to 2 per cent, aqueous hydrochloric acid in sealed
tubes to 100° for several hours, allowing them to stand for some
time after being opened, in order to observe whether any spar-
ingly soluble decomposition-product separates out in the cold. If
this is the case, the substance may be filtered off, but at the same
time it is advisable to ascertain whether any portion that may
remain in solution cannot be removed by shaking with ether,
acetic ether or chloroform. After warming to expel dissolved
traces of those liquids, the solution may be examined for glucose
(^ 61, 83, et seq. ; 200, et seq.).

The decomposition-products that are thus obtained, together
with glucose, are sometimes crystalline, as, for instance, gallic
acid, from the tannin of galls, sumach, myrobalans, divi-divi
(cf. § 151), and the yellow ellagic acid from the tannic acid
of the pomegranate and bablah fruits. But they are generally
amorphous, difficultly soluble in pure or acidified water and in
pure ether; soluble in water containing ammonia, and freely
soluble in spirit ; they are, as a rule, deep in colour, and agree in
all essential properties with the phlobaphenes mentioned in §§ 48
and 108. Some are so sparingly soluble that they may be of use
in the quantitative estimation of the respective tannins. This
is especially the case if, after the action of the acid, the liquid is
evaporated to dryness and treated with water, when they often
remain behind almost entirely insoluble.

Substances of this description are yielded by the decomposition
of the tannic acid of oak, willow, elm, fir, birch, and acacia-bark,
as well as by that from rhubarb, male-fern, ledum, wine, and by
many others. Chemically the phlobaphenes approach many resins,
with which they share the solubility in alcohol and slight solubility
in water, differing from them in their solubility in dilute ammonia,
but resembling them again in the substances they yield when
fused with an alkali. (Cf. § 42. ) Lignin and suberin also appear
to be connected with the phlobaphenes.

154

TANNINS.

The phlobaphenes mentioned in § 48 may, as stated, have been
produced from tannins during manipulation, whilst those in § 108
will probably have existed ready-formed in the material under
examination.

But, although phlobaphenes are insoluble in pure water, they
are dissolved by solutions of tannic acid, sugar, and other sub-
stances, and small quantities may therefore have been extracted
by water.

§ 161. Proneness to Decomposition. — The determination of the
glucosidal or non-glucosidal nature of a tannin is sometimes a
matter of considerable difficulty, because, on the one hand, it is
not always easily separated from any glucose with which it may
be contaminated, and, on the other hand, many tannins readily
decompose, yielding bodies resembling their mother-substances in
possessing a similar action on hide, gelatine, etc. A decomposi-
tion of this kind is observable with gallotannic acid, which,
especially on prolonged heating in aqueous solution, apparently
undergoes dissociation into a polygallic acid and sugar. Some
tannins, too, from barks, etc., appear to be capable of parting with
a portion of their glucose without completely losing their action on
gelatine, etc., which, however, rapidly diminishes, even at the
ordinary temperature, on allowing the aqueous solution to stand.
It is not surprising, therefore, that very varying statements are
met with as to the glucosidal ?.nature of a tannin, and especially
the amount of glucose certain members of the class can be made
to yield. And yet it is most important to determine whether
glucose can be obtained from a tannic acid or not. The produc-
tion of a sparingly soluble and possibly crystalline body from an
easily soluble amorphous tannin by the action of hydrochloric or
sulphuric acid (§ 160) is insufficient proof of its glucosidal nature,
since non-glucosidal tannins undergo a similar decomposition.

As a rule the action of dilute acids on a tannin results in the
formation, apart from glucose, of a single decomposition-product
belonging to the aromatic series (gallic acid, ellagic acid, phloba-
phenes, etc.), but the researches on the tannic acids of the
Nymphacese recently carried out in my laboratory by Griining
prove that two or more decomposition-products can be obtained
from one tannin. From Nymphsea alba and Nuphar luteum
non-glucosidal tannic acids were isolated, undergoing no further
separation by fractional precipitation with lead, and yielding,

§ 162. PURIFICATION. 155

when warmed with a dilute acid, gallic and ellagic acids together
with a phlobaphene.1

$ 162. Purification. — The ease with which tannins decompose
renders their preparation in the state of purity desirable for
accurate investigation a matter of considerable difficulty, and we
may confidently assert that this has not been attained with the
majority of the substances belonging to this class that have
hitherto been described.

In preparing pure tannins the following hints may be useful,
in addition to those given in §§ 49 to 51 and 60 :

1. If a tannic acid is to be separated from the alcoholic extract
it is very advisable, after evaporating, to mix at once with a con-
vsiderable quantity of water. Alcohol dissolves phlobaphenes and
resinous substances, together with tannic acid, and strong aqueous
solutions of the latter are known to be capable of taking up the
former, even if otherwise insoluble in water (§ 160).

2. In precipitating the aqueous filtrate with acetate of lead, it
is advisable to add the reagent in successive portions, rejecting
the first (generally more deeply coloured) and last precipitates, as
they are usually contaminated with foreign substances to a con-
siderable extent.

3. The lead precipitates should be washed and treated with
sulphuretted hydrogen as rapidly as possible, to avoid decomposi-
tion of the tannate of lead.

4. The filtrate from the sulphide of lead should be evaporated,
if possible, in a partial vacuum, and only to the consistence of a
thin syrup. The remainder of the water may be evaporated over
sulphuric acid and lime at the ordinary temperature, the opera-
tion being completed in vacuo.

It will frequently be found advantageous to shake the filtrate,
before evaporating, with ether or acetic ether, which would
remove any gallic acid that might be present.

Many tannins may be purified by dissolving in water, adding
chloride of sodium, and removing the tannic acid by shaking
with acetic ether or a similar solvent. This method has been
successfully used by Loewe for sumach-tannic acid and some
others,2 and by Eaabe for rhatania-tannic acid.3 It should be

1 Beitriige zur Chemie der Nymphaceen, Diss. Dorpat, 1881.
: Zeitschr. f. anal. Chem. xii. 128 ; xiv. 35, 44 (Journ. Chain. Soc. xxvii. 171 ;
xxviii. 75).
3 Pharin. Zeitschr. f. llussland, 577, 1880.

156 TANNINS.

observed that gallic acid must be removed by shaking with ether
before chloride of sodium is added, and that certain tannins are
partially precipitated by saturating their aqueous solutions with
salt ; some also can be precipitated from their aqueous solutions
by sulphuric or other mineral acid, but this method seldom yields
them in a sufficient state of purity for our purpose.

§ 163. Tannins insoluble in Water. — The tannic acids of alder1
and hop,2 together with some others, are stated to be insoluble in
water after isolation. In some instances the tannin may possibly
have been partially decomposed during the process of isolation
(§§ 48, 161). In any case in which tannins sparingly soluble in
water are anticipated, the lead precipitate should be decomposed
in the presence of spirit.

There are also a number of bodies which resemble one or other
of the tannins in certain of their properties (as, for instance, in
being precipitated by acetate of lead), but are insoluble in cold
water. Paeniofluorescin might be placed in this class.3

§164 It not unfrequently occurs that a single plant contaii
two or more tannins : for example, in addition to their own pecu-
liar tannins, both oak and willow bark contain a little gallotannic
acid ;4 myrobalans and divi-divi contain gallotannic and ellag(
tannic acid.5 If the presence of more than one tannin is antici-
pated, the method of fractional precipitation should be tried, or,
if that is unsuccessful, the examination of the products obtain*
by warming with acids may afford the information required,
was the case in the investigation of oak and willow bark ; gallk
acid can be removed by shaking with ether, whereas oak-i
cannot.

§ 165. Notes on some of the more important Tannins. — In
following notes those tannins will be mentioned first that are not
glucosides, and yield principally pyrocatechin (§ 43) by destructh
distillation.

Catechu-tannic acid is probably produced from catechin (catechuic
acid) by loss of the elements of water.6 In estimating catechu-

1 Compare "Reichardt, Chem. Centralblatt, N. F. i. 12.

2 See Etti, Polyt. Journ. cclxxxviii. 354, 1878 (Journ. Chem. Soc. xxxiv.
797) ; Bissell, Amer. Journ. Pharm. [4], xlix. 582, 1877.

3 §§44 and 147.

4 Compare Johanson, loc. cit.

5 Compare Loewe, Zeitschr. f. anal. Chem. xiv. 35, 44, 1875.

6 Compare Etti, Annal. d. Chem. und Pharm. clxxxvi. 327, 1878 ; Zeitschr.
f. anal. Chem. xii. 285, 1873 ; xiii. 113, 1874 ; Journ. f. prakt. Chem. cv.

§ 1G5. CATECHUIC ACID, ETC. 157

tannic acid good results can be obtained by using a 1 per cent.
solution of gelatine in saturated solution of chloride of ammonium
as indicated in § 52, xii. ; chloride of ammonium should be added
to the tannin solution also.1 Lehmann has shown that the liquid
may be diluted within certain limits without affecting the result
to any notable extent, and that it is advisable to promote the
subsidence of the precipitate by adding powdered glass and
vigorously stirring. He determines the end of the experiment by
removing a drop with a filtering tube and testing it with solution
of gelatine on a watch-glass with dark background. The tannin
solution should be mixed with an equal volume of saturated chlo-
ride of ammonium solution. Each cc. of the reagent indicates
00139 gram catechu-taimic acid. No other constituents of
catechu are precipitated by gelatine.

Catechuic acid (§ 151), which is easily converted into catechu-
tannic acid, should not be neglected in determining the value of
a catechu. Lehmann endeavoured to estimate it from the differ-
ence in the amount of permanganate of potassium required (cf.
§ 52, vii.) before and after precipitation with gelatine (by
which catechu-tannic acid alone is removed). The results he
obtained were, however, somewhat too high, since an infusion of
catechu contains other substances besides catechuic and catechu-
tannic acids that act upon permanganate of potassium. A more
successful process consisted in removing the catechuic acid by
shaking with ether, as directed in § 151, and then titrating it
with permanganate of potassium, reckoning 4 '8 4 parts of catechuic
acid for every 16 parts of oxygen consumed.

fihatania-tannic acid, like the two preceding substances, yields
phloroglucin and protocatechuic acid when fused with potash.2
For this tannin also Giinther recommends the estimation with
solution of gelatine, calculating 0-01302 to 0-01323 gram rhata-
nia- tannic acid for every cc. of gelatine solution. The lead pre-
cipitate, which is tolerably stable but not quite insoluble in water,
contains, according to Giinther, 31-26 per cent, of oxide of lead.

1 Lehmann, 'Vergl. Unters. einiger Catechu und Gambier-Proben,' Diss.
Dorpat, 41, 1880 ; Pharm. Zeitschr. f. Russland, No. 13, 1881.

2 Compare Raabe, loc. cit. Raabe contests the glucosidal character of
rhatania-tannic acid, and is of opinion that it simply loses water when converted
into rhatania-red. See also Chem. Centralblatt, xii. 467, 1867 ; Annal. d.
Chem. und Pharm. cxliii. 274, 1867, in which Grabowski, like Wittstein, still
maintains the production of glucose in the decomposition.

158 TANNINS.

Eaabe found 334 per cent, of oxide of lead in the lead-salt, and
16*64 of oxide of copper in the copper-salt.1

Morintannic acid, which occurs together with morin and madurin
in fustic, also yields phloroglucin and protocatechuic acid by
fusion with potash. Boiling water extracts morin from the
wood in the form of a calcium-compound, which is sparingly
soluble in cold water, and is deposited, therefore, from the de-
coction on cooling. Alcohol acidified with sulphuric acid decom-
poses the compound, dissolving the morin ; the latter crystallizes
from alcoholic solution in yellow needles, which are sparingly
soluble in cold, but more freely in boiling water. With acetate
of lead the boiling alcoholic solution gives an orange-red precipitate
containing 58*4 per cent, of oxide of lead.

According to Loewe, an aqueous solution yields both morin-
tannic add and madurin to acetic ether. By dissolving the
evaporation-residue in cold water and adding chloride of sodium
an amorphous precipitate of the former is obtained, whilst the
latter crystallizes out on standing. Maclurin is insoluble in a
mixture of equal volumes of water and saturated solution of salt,
whereas morintannic acid is dissolved. Morintannate of lead
contains 6 4 '23 per cent, of oxide of lead. No accurate method
of estimation is known.

The doubt that has recently been thrown upon the glucosidal
nature of rhatania-tannic acid renders it very desirable that kino-,
tormentil- and bistort-tannic acids should be examined afresh.2
These tannins yield similar products when fused with potash.
Kino-tannic acid is characterized by the disposition its alcoholic
solution shows to gelatinize. According to Giinther both kino-
and tormentil-tannic acids can be estimated by gelatine-solution
(see above, and also § 52, xii.), 1 cc. of which indicates O'OL
gram kino, and 0*0168 gram tormentil-tannic acid.

For ellago-tannw acid see below.

The tannin of the horse-chestnut? which is likewise non-glucosi(

1 Possibly there is another copper-salt containing 22 to 23 per cent. CuO
that would, at least, appear probable from some experiments of Giinther.

2 For the tannin of kino see Eisfeldt, Annal. d. Chem. und Pharm. xcii.
101, 1854 ; for its crystalline decomposition-product, kinoin, see Etti, Ber. d.
d. chem. Ges. xi. 1879 (Journ. Chem. Soc. xxxvi. 159). Tormentil-tannic
acid is discussed by Rembold, Annal. d. Chem. und Pharm. cxlv. 5, 1868
(Amer. Journ. Pharm. xl. 311).

3 Compare Chem. Centralblatt, x. 318 ; xii. 513.

§ 165. GALLOTANNIC ACID. 150

.irtially precipitated from aqueous solution by chloride of
sodium, and by acid sulphite of potassium. The aqueous or
alcoholic solution turns dark cherry-red when warmed with
hydrochloric or sulphuric acid, and deposits red flocks ; bichromate
of potassium produces a dark colouration and brown precipitate ;
with ferric chloride it strikes a green, or, if the solution is am-
moniacal, a violet colour ; it is not precipitated by tartar emetic.
\ i • method is known by which it can be accurately estimated.

Amongst the glucosidal tannins those may be mentioned first
which, when boiled with dilute acids, yield, in addition to glucose,
crystal-line decomposition-products. The most important of them
is —

Gallotannic add, the decomposition-product of which, gallic
acid, has been already alluded to (§ 151). Its quantitative esti-
mation is comparatively easy, as fairly accurate results can be
obtained both volumetrically by titration with gelatine-solution
or with permanganate of potassium, and gravimetrically by pre-
cipitation as tin (stannous), copper, or lead-salt. A few sources
of error must, however, be here alluded to. In the first place,
if the tannic acid has been extracted by water, mucilage and
gallic acid may also have passed into solution ; the latter is pre-
cipitable by gelatine in the presence of mucilage. That is avoided
by extracting with spirit. In the second place, gallic acid, as
already pointed out, acts upon permanganate of potassium. In
titrating with a solution of that substance, therefore, either the
gallic acid must be removed by shaking with ether, or, as sug-
gested by Lowenthal, and mentioned in §§ 52, 53, two estima-
tions must be made, the one before, the other after, precipitating
the tannic acid with gelatine, the calculations being made from
the difference. In precipitating with acetate of lead or copper
(but not with ammonio-chloride of tin), gallic acid is also partially
carried down, and should therefore be previously removed. From
a solution containing about 2 per cent, of tannin the tin precipi-
tate will contain 1977 to 1979 per cent, of stannous oxide, the
'•OOO per cent, of oxide of lead, and the copper 38*28 per
cent, of oxide of copper.

Hammer's method (§ 52, xi.) may, as already stated, be best
applied to the estimation of gallo-tannic acid.

The tannins of sumach,1 knoppern galls, valonia and algaro-

1 Compare Giinther, 'Beitr. zurKenntn. der im Sumach, etc., vork. Gerbs./
Di.ss. Dorpat, 1871 (Journ. Chem. Soc. xxiv. 762) ; Loewe, Zeitschr. f. anal.

160 TANNINS.

billa1 correspond exactly to gallotannic acid, and all that has beei
said of the latter is equally true of the former. They are always
accompanied by gallic acid in the materials that yield them.

Some of these also contain the so-called ellago-tannic acid,
which is found in notable quantities in myrobalans, divi-divi and
bablah fruits.2

This ellago-tannic acid, which, as far as Loewe's experiments
show, is not a glucoside, differs from gallotannic acid in yielding
ellagic in the place of gallic acid, a change that can be brought
about by water alone at a temperature of 108° to 110°. Ellagic
acid can be obtained in sulphur-yellow crystals, which are almost
insoluble in boiling water or in ether, and sparingly soluble in
alcohol. Notwithstanding, however, its slight solubility in ether,
small quantities can be removed from aqueous solution by shak-
ing with that liquid. Ferric chloride produces first a green, then
an inky colouration. It is soluble in potash, and is precipitated
by acetate of lead from an alcoholic solution in the form of lead-
salt, containing 63 per cent, of oxide. The dry substance heat
with zinc dust yields the hydrocarbon ellagene (C14H10), wl
cannot be combined with picric acid.

Whether ellago-tannic acid has been prepared in a state
purity, and whether it is identical with punico-tannic acid,3
questions which we may for the present leave out of considei
tion. According to Rembold, the latter also yields ellagic ack
Special methods for the estimation of these two substances h
not as yet been published.

For nymphsea-tannic acid see § 161.

Gallotannic and gallic acids also occur in tea, accompanied
quercetin (possibly present in sumach also, § 152), and by the
called boheic acid.4 The latter is not thrown down when acetate
of lead is added to a hot infusion of tea, but is precipitated on

Chem. xii. 128, 1873 (Journ. Chem. Soc. xxvi. 748) ; xiv. 46 (tannin of
knoppern-galls).

1 Compare Godeffroy, Zeitschr. d. Oesterr. Apoth.-Ver. 132, 1879 (Year-book
Pharm. 215, 1879).

2 Compare Giinther, loc. clt. Also my observations in the Jahresbericht f.
Pharm. 192, 1875 ; and Loewe, Zeitschr. f. anal. Chem. xii. 128 ; xiv. 35, 44.

3 Annal. d. Chem. und Pharm. cxliii. 285, 1867. I may observe that in the
pomegranate bark also the substance yielding ellagic acid is accompanied by
gallotannic acid, and that Rembold obtained sugar by the decomposition of
the former.

4 Compare Hlasiwetz, Annal. d. Chem. und Pharm. cxlii. 233.

$ 165. QUEECITANNIC ACID. 161

adding ammonia. It is pale yellow, amorphous, and easily
sol ul »le in alcohol.

('ttffi'ti-ftniii'ir1 acid yields sugar and crystalline caffeic acid.
( 'afl'eie acid is easily soluble in alcohol, sparingly in cold water,
and strikes a dark green colour with ferric chloride, which is
turned red by soda. It reduces silver salts on warming, but not
alkaline copper solution. Like caffea-tannic acid, caffeic acid
yields pyrocatechin by dry distillation. The former is also coloured
green by ferric chloride. Its ammoniacal solution turns green
\vlion exposed to the air (viridic acid). According to Giinther's
experiments, it cannot be quantitatively determined by precipita-
tion with copper, lead, or gelatine. Titration with permanganate
of potassium might possibly yield approximate results.

The following tannins are provisionally considered by many
chemists to be glucosides (see note) ; they yield amorphous de-
composition-products resembling phlobaphenes. (Cf. § 160.)

(Jimrcitannic acul, which is probably identical with the tannic
acids of willow and elm bark,2 is one of the less stable tannins, and
is therefore, extremely difficult to purify and to estimate (§ 161).
The copper and lead salts seem specially liable to be decomposed
by the combined action of air and water, whilst even the tannic
acid itself in aqueous solution rapidly undergoes change. To
have any value, therefore, estimations by gelatine or perman-
ganate of potassium must be made with perfectly fresh infusions.
But the mucilaginous and other substances that are simultane-
ously dissolved by water from the oak-bark, also act upon the
•nts and render the estimation inaccurate. By extracting
with alcohol such foreign substances are excluded ; but the estima-
tion cannot be made in alcoholic solution, and distillation can
scarcely be effected without partial decomposition of the tannin.

1 See Hlasiwetz, Annal. d. Chem. und Pharm. cxlii. 220, 1867 (Amer. Journ.
xxxviii. 504) ; also Mulder und Olaanderen, Jahresb. f. Chem. 261, 1858.

upare E. Johanson, ' Beitr. zur Chem. d. Eichen-, Weiden-, undUlmen-
rinde,' Diss. Dorpat, 1875 ; Grabowski, Annal. d. Chem. und Pharm. cxlv. 1,
1868. For oak-red see also Bottinger, ibid. ccii. 269, 1880. Loewe has re-
cently contested the glucosidal nature of quercitannic acid. Compare Zeitschr.
f. anal. Chem. xx. 208, 1881 (Journ. Chem. Soc. xl. 901). Loewe believes
oak-red to be a kind of anhydride produced from the tannic acid by loss of 4 or
•lecules of water. Bottinger (Ber. d. d. Chem. Ges. xiv. 2390 ; Journ.
Chem. Soc. xl. 1041) considers quercitannic acid itself to be a glucoside, and
points out the difference between that substance and another constituent of
oak -bark also soluble in water and capable of tanning. The latter was the
b.nlv isolated by Loewe.

11

162

The best results would probably be obtained by extracting
directly with alcohol, evaporating the tincture in a partial
vacuum, treating the residue with water, quickly filtering and
estimating at once with gelatine or permanganate of potassium.
(Cf. §§ 51, 52, VII. and XII.) In standardizing the solutions,
it may be useful to remember that, according to Giinther's
experiments, quercitannic acid, though differing greatly in other
respects from gallotannic acid, possesses the same quantitative
action on permanganate of potassium. It must be observed
that tannic acid is deposited when its solution is completely
saturated witn chloride of ammonium ; it is advisable, therefore,
when precipitating with gelatine, to follow the directions given
for titrating catechu-tannic acid. Quercitannic aciti is sparingly
soluble in ether; ferroso-ferric salts produce inky mixtures with
its aqueous solution; other of its properties are mentioned in
§§ 49, 51. The lead salt obtained by precipitation with a
slight excess of the acetate contains 56 to 57 per cent, of oxide,
the copper salt 2 9 '5 per cent. The oak-red produced artificially
from the tannic acid is identical with the phlobaphene that occui
naturally in the bark. It is likewise coloured black by iron sal
yields protocatechuic acid and phloroglucin when fused wil

potash, and possesses the properties of a phlobaphene

enumerated in §§ 108, 160.

The tannins of the pine,1 lirch, many species of acacia, etc.,

which have been but little investigated, may possibly resembl

quercitannic acid in many of their essential characters.

Filix-tannic add - is resolved, on boiling with acids, into glue

and red flocks of filix-red ; the latter closely resembles cinchom

red.

Cinchona-tannic acid 3 undergoes a similar decomposition wit

production of cinchona-red. Its lead salt is somewhat easil]

soluble in acetic acid.

1 Compare Kawalier, Wiener Akad. Ber. xi. 354 et seq. ; Eochleder
Kawalier, ibid. xxix. 22 et seq. ; Wittstein Vierteljahresschr. f. pract. Pharm.
iii. 14, 1854.

2 See Malin, Chem. Centralblatt, xii. 468, 1867. For tannaspidic acid and
pteritannic acid, the former of which Malin believes to be impure filix-red, see
Luck, ibid. 657, 676, 1851. Compare further Grabowski, Annal. d. Chem.
und Pharm. cxlii. 279, 1867.

3 Compare Rembold, Annal. d. Chem. und Pharm. cxliii. 270, 1867, and
Schwarz, Chem. Centralblatt, 193, 1852.

$ 1GG. GLUCOSIDES OTHER THAN TANNINS. 163

Cinckona-nova-tannic acid1 yields, according to Hlasiwetz, under
;ime conditions, sugar and cinchona-nova-red ; the latter is
easily soluble in ether.

For ipecacuanha-tannic add 2 see Willigli and Podwissotzki ; for
leditannic acid, Willigh3 and Eochleder and Schwarz;4 for
acid, Phipson;5 for the tannin of mate, Arata;6 for
acid, Dragendorff.7 Information concerning some
-other tannins may be gained from Gmelin's 'Chemistry.'

OTHER GLUCOSIDES.

§ 166. Cyclopin, Rhinantliin, etc. — Cyclop in, which, however,
•cannot, without some consideration, be classed with the tannins,
is a glucosidal substance found by Greenish,8 in the so-called Cape
or Bush tea. It is freely soluble in water, and is precipitated from
solution by acetate of lead, as well as by digestion with the
oxyhydrate of that metal ; from the combinations with lead thus
obtained, it can be liberated by sulphuretted hydrogen. Ether
precipitates it from alcoholic solution. Boiled with 4 per cent,
hydrochloric acid, cyclopin decomposes into glucose and cyclopia-
red, which latter is insoluble in ether. With strong hydrochloric
iicid, the solution turns rapidly red. Cyclopin is not precipitated
by gelatine or tartar emetic, and does not possess an astringent
taste. In the plant producing it, it appears to be easily converted
into oxycyclopin, which is insoluble in alcohol, and undergoes a
similar decomposition to cyclopin itself.

Another glucoside that yields a deeply coloured decomposition-
product when boiled even with very dilute acids, is the rhinanthw,
occurring in various species of Rhinanthus, Alectorolophus, and
Melampyrum.9 It can be obtained in colourless acicular crystals,
soluble in water and alcohol, insoluble in ether, and not preci-

1 See Hlasiwetz, Annal. d. Chem. uncl Pharm. Ixxix. 130, 1857.
0 Journ. f. pract. Chem. li. 404 ; Pharm. Zeitschr. f. Russland, xix. 1.
Pharm. Journ. Trans. [3], x. 642.
a Chem. Centralblatt, 790, 1852.
4 Zeitschr. f. anal. Chem. v. 668, 1869.
0 Ibid. p. 812.
* Jahresb. f. Pharm. 164, 1878. Compare also Byasson, ibid.

7 Archiv d. Pharm. [3], xii. 113, 1878.

8 Sitzb. d. Dorpater Naturforscher-Ges. 345, 1SSO (Pharm. Journ. and Trans.
[3], xi. 549). It is accompanied by the crystalline cycbpia-Jftwreicin, which

-ible in ether and alcohol but sparingly soluble in water. Potash dissolves
it with yellow colour and production of a fine green fluorescence.

9 Compare Ludwig, Archiv d. Pharm. cxlii. 199, 1870.

11—2

164

GLUCOSIDES OTHER THAN TANNIN*.

pitated by acetate of lead. Boiled with dilute [hydrochloric acid
it yields rhinanthogenin, which is of a dark bluish-green colour, and
insoluble in water.

Some alkaloids, too, possess the property of yielding, under
similar conditions, deeply coloured decomposition-products, as for
instance, rhoeadine, thebaine (§ 189).

§ 167. Other important Glucosides; Sulubilit-y. — A remarkable
peculiarity of the above, as well as a number of other glucosides,
is that, although more or less easily dissolved by alcohol, they are
sparingly or not at all soluble in ether. Certain glucosides that
have been mentioned, where necessary, in the foregoing chapters
show a similar insolubility in ether (compare convolvulin, § 153;
digitalein and digitonin, § 155; chrysophan, §148, etc.); in fact, this
negative property may be said to be characteristic of the majority
of glucosides.

Nitrogen enters into the composition of some few of the members
of this class, and certain of them, when acted upon by ferments or
acids, yield in addition to sugar a volatile decomposition-product of
characteristic odour ; but this is not the case with most of them.

The following are some of the better-Jcnown glucosides that are
soluble in alcohol, contain nitrogen, and yield a volatile decomposition-
product.

Amygdalin and laurocerasin 1 are both tolerably easily soluble in
water (amygdalin in 12 parts), and in boiling alcohol of sp. gr.
0'819, but more sparingly in cold. They are insoluble in petro-
leum spirit, and are precipitated by ether from alcoholic solution.
Amygdalin crystallizes with facility in bitter scales belonging to
the monoclinic system. Laurocerasin has not yet been obtained
in crystals. They are both laevo-rotatory. Cone, sulphuric acid dis-
solves them with pale reddish-violet colour. Emulsin easily resolves
them into glucose, oil of bitter almonds, and hydrocyanic acid,
the latter body being produced in larger quantity from amygdalin
than from laurocerasin. The reason for this is to be found in
the fact that in laurocerasin half of the cyanogen in the amygdalin
group has been already converted into formic acid, so that lauro-
cerasin may be regarded as amygdalate of amygdalin. On boiling
amygdalin and laurocerasin, therefore, with baryta-water, the
former will yield one molecule of ammonia for every molecule of

1 Compare Lehmann, * Ueber das Amygdalin der Kirschen, Pflaumen,' etc.,
Diss. Dorpat, 1874,

§ 167. AMYGDALIN; ESTIMATION. 105

barium salt formed, whilst from the latter only one of the former
can l)e obtained for every two of the latter.1

Methods for the quantitative estimation of amygdalin have
been proposed by Bieckher a and Feldhaus.3 That of the latter
is based upon the decomposition of the amygdalin by emulsin in
aqueous solution and estimation of the hydrocyanic acid produced.
Almonds are freed from oil, powdered and macerated with water
for twenty-four hours. The hydrocyanic acid is then distilled off
in a current of steam, received in ammoniacal water, and estimated
as cyanide of silver. Anyone that has distilled bitter-almond
water, or brought hydrocyanic acid into contact with powerful
alkalies, will know that this method is very faulty. To obtain
even approximate results I think it must be necessary that (a) the
flasks in which the maceration is conducted should be completely
filled with the mixture, and (b) the use of ammonia or other
powerful base should be avoided.

In Rieckher's method the amygdalin is decomposed by hydrate
of barium, a reaction which, according to Lehmann, takes place
tolerably smoothly. One reason for preferring this process to Feld-
haus's is, that the result can be checked by estimating on the one
hand the ammonia liberated, and on the other the amygdalate of
barium produced. The latter can be determined in the solution
after expulsion of the ammonia by removing the excess of barium
with carbonic acid gas, and then decomposing with sulphuric acid
the amygdalate of that metal which has been left in solution.
From the sulphate of barium thus obtained the amount of amyg-
dalin acted upon can be calculated. This method cannot, how-
ever, I think, be applied directly to almond meal deprived of fat,
but only to the impure amygdalin obtained by exhausting with
boiling alcohol and precipitating with ether.

Myronate of potassium crystallizes in rhombic prisms, which are
freely soluble in water, sparingly in cold alcohol, but are dissolved
by warm (50° to GO0) 85 per cent, spirit. Myronic acid itself is also
vsoluble in cold strong spirit, but rapidly decomposes. In aqueous
•solution myronate of potassium is easily resolved by ferments,
especially by the myrosin of white and black mustard (but not

1 It is remarkable that Lehmann could find cane-sugar in the seeds of the
apple, pear, cherry, plum, peach, and bitter almond, which contain crystal-
lizable amygdalin, whilst sweet almonds yielded glucose only.

- X. .lahrb. f. Pharm. xxiv. 65. 3 Archiv d. Pharm. clxvi. 52.

166 GLUCOSIDES OTHER THAN TANNINS.

by emulsin) into volatile oil of mustard (sulphocyanide of allyl,
§ 29), characterized by its extreme pungency, glucose and bisul-
phate of potassium. A quantitative estimation might possibly be
made by freeing the finely-powdered seeds from oil, exhausting
with warm 85 per cent, spirit, and digesting the tincture for
some time with carbonate of barium. From the filtrate the
alcohol might be recovered by distillation, the residue dissolved
in water, and digested with myrosin at a temperature of about 40°,
the barium being finally precipitated as sulphate by the addition
of hydrochloric and sulphuric acid. One molecule of sulphate of
barium indicates 6ne of myronic acid.1

White mustard contains no myronic acid, but in its stead
another glucoside, to which the name of sinalbin has been given.
Like myronic acid, it dissolves in boiling 85 per cent, spirit,
separating out again to a great extent on cooling. It is crystal-
line, insoluble in ether and bisulphide of carbon; sparingly
soluble in cold, freely in hot alcohol, and in water. Alkalies
colour it 'yellow, nitric acid transiently blood-red. It reduces
alkaline copper solution, and is precipitated by mercuric chloride
and nitrate of silver. Warm solution of caustic soda converts it into-
sulphate and sulphocyanide of soda; myrosin into glucose, acid
sulphate of sinapine and sulphocyanate of acrinyl (C7H70, NCS).

Sulpliocyanate of sinapine, which also occurs in white mustard, is
not glucosidal, and differs from sinalbin in being more easily
soluble in cold alcohol, and in yielding the sulphocyanide reaction
directly with ferric chloride.2

Ericolin and menycmthin3 are glucosides containing no nitrogen,
but yielding easily volatile decomposition products. The former
has been described in § 155. Menyanthin is freely soluble in
warm water and in alcohol, but insoluble in ether. Cone, sul-
phuric acid dissolves it with the gradual production of a reddish-
violet colouration. Warming with dilute sulphuric acid resolves
it into glucose and menyanthol, the latter possessing a penetrating
odour. Menyanthin is precipitated by tannic acid, but not by
acetate of lead.

1 Compare Will und Kiirner, Annal. d. Chem. und Pharm. cxxv. 257, I860.
(Am. Journ. Pharm. xxv. 323.)

2 Compare Will und Laubenheimer, Annal. d. Chem. und Pharm. cxcix.
150, 1879 (Pharm. Journ. and Trans. [3], x. 918). Babo und Hirschbrunn,
ibid. Ixxxiv. 10, 1852.

8 Compare Kromayer, foe. at. ; Liebelt, Jahresb. f. Pharm. 119, 1877.

§ 167. CONIFERIN. 167

Pinipicrm is described by Kawalier1 as being freely soluble in
water and alcohol, insoluble in pure ether, and not precipitable by
basic acetate of lead. Its decomposition-products resemble those
of ericolin.

Of glucosides which yield either fixed or difficultly volatile decom-
position-products not possessing any characteristic odour, the follow-
ing may be mentioned.

Coniferin is sparingly dissolved by cold, but freely by warm
water and by alcohol. It crystallizes in glistening needles, and
melts at 185° (uncorr.). With cone, sulphuric acid it forms a
violet solution, and when moistened with hydrochloric acid and
phenol develops a blue colouration. Dilute acids resolve coni-
ferin into sugar and a resinous substance ; with emulsin it yields a
crystalline decomposition-product. The latter, which is sparingly
soluble in water and alcohol, can be removed by ether from its
aqueous solution. Its melting-point lies between 73° and 74°.
Coniferin, when exposed to the air, gradually acquires a vanilla-
like odour, a change rapidly brought about by warming with
dilute sulphuric acid and bichromate of potassium, and caused by
the decomposition of the coniferin with the production first of the
methyl-ethyl ether of protocatechuic aldehyde, and finally of
•vanillin'2 (§ 15,")). The reaction with hydrochloric acid and phenol
ma}- be used in testing for coniferin microcliemically in the cam-
bium of conifers.

The identity of this substance with the coniferin of Tangel,3
detected in sections of conifers by the red colouration produced
by cone, sulphuric acid and phenol, must be left for the present
an open question. Miiller 4 has shown that the hitter also occurs
in most indigenous trees (Salix, Populus, Prunus, Acer, Quercus,
etc.), and is to be met with in abundance, especially in the autumn,
in the hard bast and alburnum. According to Miiller, the phenol
only hastens the appearance of the red colour.

Arbutin* is sparingly soluble in cold alcohol, ether, and cold

1 Chem. Centralblatt, 705, 724, 1853.

2 Compare Tiemann und Haarmann, Ber. d. d. chem. Ges. vii. 609, 1874
(Journ. Chem. Soc. xxvii. 895). See also Kubel, Journ. f. pract. Chem.
xcvii. 243, 1866.

3 Flora, Ivii. Xo. 15, 1874.

4 Ibid. No. 25.

•> Compare Kawalier, Chem. Centralblatt, 761, 1852 ; Strecker, Annal. d.
Chem. und Pharm. cvii. 288, cxviii. 292, 1861 ; Hlasiwetz and Habermann,
ibid, clxxvii, 334, 1875 (Journ. Chem. Soc. xxix. 78, xxx. 298).

168 GLUCOSIDES OTHER THAN TANNINS.

water, but the latter solvent dissolves it with facility when
warmed. Dilute sulphuric acid resolves it into glucose, hydro-
quinone and methyl-hydroquinone. Both of the latter can be
extracted by shaking with ether, and, when warmed with dilute
sulphuric acid and peroxide of manganese, yield quinone, recog-
nisable by its characteristic iodine-like odour. Acetate of lead
does not precipitate arbutin.

Daplinin1 differs from arbutin in being precipitated by acetate
of lead. It is sparingly dissolved by cold, but freely by warm
water and by alcohol, and is insoluble in ether. Alkalies colour
it yellow. Acids and ferments resolve it into sugar and daph-
netin ; the latter can be partially sublimed without decomposi-
tion.- Certain other constituents of mezereon bark yield umbelli-
ferone (§ 27) by dry distillation.

Salicin crystallizes in colourless needles and scales, which have
a powerful action on polarized light, and are freely soluble in
boiling water and alcohol, but much less so in cold. It is insolu-
ble in ether. From aqueous solution it can be extracted by
amylic alcohol (§ 56). Hydrate of lead does not combine with it.
Boiling with dilute acids decomposes salicin into sugar and sali-
genin or saliretin, both of which substances can be removed by
shaking with ether. If an aqueous solution of salicin or saligenin
is boiled with dilute sulphuric acid and bichromate of potassium,
salicylous acid is produced. (Of. § 25.) Cone, sulphuric acid
dissolves salicin, saligenin, and saliretin with production of a fine
red colour. Salicin strikes a beautiful violet with Frohde's reagent.
These reactions can also be employed for the microchemical detec-
tion of salicin.

Populin yields benzoic acid in addition to the above-mentioned
decomposition-products when acted upon by dilute acids (cf.
§ 26), and salicylous acid when warmed with chromic acid. With
cone, sulphuric acid a red colouration is developed, and with
Frohde's reagent a violet, which, however, is somewhat less intense
than that yielded by salicin under similar conditions. It is con-
siderably less soluble than the latter in water and in alcohol, and
can be removed from aqueous solution not only by amylic alcohol
{like salicin), but also by chloroform and (with difficulty) by

1 Compare Zwenger, Annal. d. Chem. xmd Pharm. xc. 63, 1858 (Amer.
Journ. Pharm. xxxiii. 325).

S 167. VENZOHELICIN, ETC. !69

benzene (§ 55). Populin decomposes with far greater facility
than salicin.

jBenzoMicin,1 detected by Johanson in willow hark, forms colour-
less crystals, soluble in water and alcohol. With cone, sulphuric
acid it turns yellow. Frdhde's reagent does not produce a violet
colouration. Boiling with not over-dilute hydrochloric acid
resolves benzohelicin into glucose, benzole acid, and a resinous
substance that dissolves blood-red in cone, sulphuric acid.

Philyrin2 is much less soluble in water and alcohol than is
salicin, and yields under the influence of dilute acids, glucose and
philygenin, a polymer of saligenin. Both philyrin and philygenin
dissolve in cone, sulphuric acid with red colouration.

Phlorrhizin 3 crystallizes in colourless needles sparingly soluble
in cold water, easily in hot. Ethyl and methyl alcohol dissolve it
with facility, ether with difficulty. Dilute acids resolve it into
glucose and phlorrhetin. Cone, sulphuric acid forms red solutions
with both phlorrhizin and phlorrhetin ; with Frohde's reagent a
splendid royal-blue colouration is rapidly developed. Moistened
with ammonia and exposed to the air, phlorrhizin turns yellow,
red, and finally blue.

JEsculin can likewise be obtained in colourless needles soluble
in 12 -5 parts of boiling, 672 of cold water; in 24 of boiling, and
120 of cold absolute alcohol. Chloroform removes it from
aqueous solution (§ 55). Boiling with dilute acids resolves it into
glucose and sesculetin. The latter yields a yellow solution with
alkalies ; it is also soluble in bisulphite of ammonia, and if such a
solution be mixed with ammonia and shaken with air, at first
blood-red and subsequently a deep blue colour is developed. The
very characteristic blue fluorescence of aesculin is increased by
alkalies and destroyed by acids.

Fraxin possesses a similar fluorescence, and can also be obtained
in colourless crystals. It is more sparingly soluble in water and
absolute alcohol than sesculin, but more freely in ether, to which
it imparts its fluorescence. Ferric chloride is said at first to strike

1 See Johanson, loc. cit. Piria, Annal. d. Chem. und Pharm. Ixxxi. 245,
1852; xcvi. 375, 1855 (Amer. Journ. Pharm. xxiv. 241, xxviii. 259).

2 Compare Campona, Annal. d. Chem. und Pharm. Ixxxi. 245, xcvi. 375.

3 For isophlorrhizin, see Ilochleder, Journ. f. pract. Chem. civ. 397, 1868
(Amer. Journ. Pharm. xli. 419).

170 GLUCOSIDES OTHER THAN TANNINS.

a green colour and subsequently yield a yellow precipitate:
Fraxin is thrown down by acetate of lead.1

Syrincjln (§ 55) crystallizes in colourless needles, dissolves with
difficulty in cold water, more easily in hot water and alcohol, but
is insoluble in ether. Basic acetate of lead does not precipitate it
from aqueous solution. Cone, sulphuric acid dissolves it with
deep blue colouration ; Frohde's reagent, blood- red passing to-
violet ; cone, nitric acid, deep red. Chloroform extracts syringin
from aqueous solution.2

For globularin see Walz;3for coriamyrtin compare § 155; for
inttosporiu see v. Miiller ;4 for samaderin see de Yrij.5

Colocynthin can be obtained in yellowish crystals which dissolve
in cone, sulphuric acid with the gradual production of a fine red
colour ; Frohde'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 basic acetate of lead
and b}^ tannin.

Bryonm is also precipitated by the latter reagent.6

For ononin, which gradually assumes a cherry-red colour with
cone, sulphuric acid, see Hlasiwetz.7

Apiin crystallizes 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. In dilute alkalies apiin
dissolves with yellow colouration.

For datiscin, which is also coloured yellow by alkalies, see
Braconnot8 and Stenhouse.9 Ferric chloride precipitates it green ;

1 For a number of other glucosides and allied substances (argyraescin,
aphrodfescin, 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 syringopicrin (easily soluble in water), ibid. cix. 26, 1862.

3 N. Jahrb. f. Pharm. vii. I, 1857 ; xiii. 281, 1860.

4 ' The Organic Constituents of Plants,' Melbourne, 1878.

5 Chem. Centralblatt, 92, 1859 ; Jahresb. f. Pharm. 208, 1872. SeeBlume,
Amer. Journ. Pharm. xxxi. 342.

6 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. xcviii. 166, 1856 (Journ. Chem. Soc. ix.
226). For helianthic acid compare Ludwig und Kromayer, Archiv d. Pharm.
[2], xcix. 1, 1848 (Amer. Journ. Pharm. xxxii. 135).

§ 167. HESPEIUDIN, ETC. 171

acetate of lead, yellow. Zander l has recently found a glucoside
allied to datiscin in the seeds of Xunthium strumarium. For
2>}w<1in, which can easily be extracted by shaking with chloro-
form (§ 55), see Dessaignes and Chautard ? for dukamarin, see
Geissler.3 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. Cone, sulphuric acid
dissolves it with red colouration passing to rose j with alkalies it
forms reddish-brown solutions.

Hesperidin shows a disposition to form sphaero-crystals. 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 ;4 cone, sulphuric acid gradually bright red
(limonin the same). Acetate of lead produces no precipitate. If
a solution in dilute potash is evaporated to dryness, the residue is
coloured red, passing to violet when warmed with excess of dilute
sulphuric acid. Hesperidin can be recognised under the microscope
as spha?ro-crystals soluble in warm alcohol.

Crocin (polychroite) forms a dark red powder sparingly soluble
in ether and water, more easily in alcohol. Cone, sulphuric 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.5

Glycyrrhmn9 is deposited from glacial acetic acid in sphsero-
crystalline masses of prismatic needles. After purification with
acetic acid it is almost insoluble in water (forming a jelly with it),
1 tut 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.

1 'Chem. liber die Samen von Xanthium strumarium,' Diss. Dorpat, 1880.
s". Kepert. f. Pharm. i. 216, 1851 (Amer. Journ. Pharm. xxv. 135, 136).

:i Archiv d. Pharm. [3], vii. 289, 1875 (Pharm. Journ. and Trans. [3], vi,
1010).

4 Compare Hoffmann, Ber. d. d. chem. Ges. ix. 250, 685, 1 876 (Journ.

Chem. Soc. xxx. 420, 421) ; for aurantiin, murrayin, limonin, ibid. ; also

Hilger, ibid. 26 (Journ. Chem. Soc. xxix. 709). For naringin, see Archiv d.

1'haim. [3], xiv. 139, 1879. See also Dehn, Zeitschr. f. anal. Chem. ii. 103,

: and Tiemann und Will, Ber. d. d. chem. Ges. xiv. 946, 1881.

'* See Weiss, Journ. f. pract. Chem. ci. 65, 1868 ; Stoddart, Pharm. Journ.
and Trans. [3], vii. 238, 1876.

(i Compare Habermann, Annal. d. Chem. und Pharm. cxcvii. 105, 1S7S>
(I'hann. Journ. and Trans. [3]. x. 45, 1879). Habermann changes the name
t<> ulyeyrrhizic acid.

172 GLUCOSIDES OTHER THAN TANNINS.

alcohol, and is almost insoluble in ether. Cone, sulphuric acit
precipitates it from aqueous solution ; acetate of lead and chloride
of calcium, from alcoholic. Neese's method for the quantitative
determination of glycyrrhizin is based upon the precipitation by
sulphuric acid.

For panaquillon, see Garriques j1 for thevetin, compare de Vrij ;-
for chamcelirin, see Greene.3

Cyclamin (Primulin) is crystalline and dissolves freely in water ;
the solution froths when shaken. It is easily soluble in dilute
alcohol also, but sparingly in absolute, and insoluble in ether. 4
It is said to bear 'a close resemblance to saponin. (Of. §§ 77 et seq.;
§ 167.)

For gratiolin, see Marchand 5 and Walz ; 6 for paridin, AValz 7
andDelffs.8

For convallarin and convallamar'm, see Walz. 9 The former is
sparingly soluble in water, but imparts to it the property of
frothing ; it is freely soluble in alcohol, but insoluble in ether.
The latter dissolves more easily in water, is precipitated by tannin,
and turns gradually violet when exposed to the air in contact
with sulphuric acid. Warming with hydrochloric acid colours, it
red. Convallamarin can be extracted by shaking with chloro-
form (§ 55).

Hellebonn and ketteborem.™ — The former is sparingly soluble in
cold water, freely in alcohol and chloroform ; the latter easily in
water, more sparingly in alcohol, and insoluble in ether. It can
be extracted by shaking with chloroform (§ 55). Both dissolve

1 Chetn. Centralblatt, 721, 1854 (Amer. Journ. Pharm. xxvi. 511).

2 N. Jahrb. f. Pharm. xxxi. 1, 1869. Compare also Jahresb. f. Pharm.
112, 1877 ; Bias, Amer. Journ. Pharm. xli. 310.

3 Amer. Journ. Pharm. 1. 250, 1878.

4 Compare Mutschler, Annal. d. Chem. und Pharm. clxxxv. 214, 1877
(Year-book Pharm. 145, 1878). See also Luca, Compt. Rend. Ixxxvii. 297,
1878 (Pharm. Journ. and Trans. [3], vii. 876, 1877).

5 Journ. de Chim. med. xxi. 517 (Amer. Journ. Pharm. xvii. 281).

6 Jahrb. f. Pharm. x. 317, xiv. 70, 1852, xxi. 1, 1863, where certain other
constituents of gratiola are also treated of. (Amer. Journ. Pharm. xxxi. 340).

7 Jahrb. f. Pharm. iv. 3, v. 284, vi. 10 ; N. Jahrb. f . Pharm. xiii. ] 74,
1860.

8 Ibid. ix. 25, 1858.

9 Ibid. x. 145, 1858 (Amer. Journ. Pharm. xxi. 577).

10 Compare Husemann and Marme, Annal. d. Chem. und Pharm. cxxxv. f>5,
1865 (Pharm. Journ. and Trans. [2], vii. 621, 1866).

S 1G7. VILLAIN', SENEGIN, SAPONIX. 173

in cone, sulphuric acid, with immediate production of a fine red
colouration.

For digital hi and dif/italcin, see § 155.

Scillain, a glucoside obtained from Scilla maritima, resembles
diiiitalin in physiological action. It is sparingly soluble in cold
water, but freely in alcohol, and when boiled with dilute hydro-
chloric acid is decomposed into sugar and a second substance,
soluble in ether. Concentrated hydrochloric acid is coloured red
when boiled with scillain, and this is followed by the separation
of a greenish fiocculent deposit. Concentrated sulphuric acid
dissolves it brown, with green fluorescence, and the solution is
coloured bluish-red by bromine. Basic acetate of lead does not
precipitate scillain.1

Saponin and d'ujUon'm are likewise glucosides ; they have already
been described in §§ 77, 78, 79, 155, where mention has been
made of their insolubility in absolute alcohol. My object in
referring to them again here, is to draw attention to the resem-
blance they bear, in many respects (frothing of the solution, etc.),
to the preceding glucosides (cyclamin, etc.). The following sub-
stances are also allied to saponin :

Scneg'm — which, however, is possibly identical with saponin —
was found by Christophsohn 2 to differ from that body only in
the rapidity with which the violet colouration was produced by
sulphuric acid. It can be estimated by the methods detailed
in $ 7S.

Christophsohn also proved that both saponin and senegin are
accompanied in the drugs yielding them by another substance that
has a much more powerful action on the heart than either of those
principles themselves. This other substance remains in solution
after separation of the saponin by baryta-water, but could not be
obtained in a state of purity.

M'l<mthiii, found by Greenish3 in the seeds of Nigella sativa,
is not precipitated by ether from alcoholic solution. It resembles
suponin in being freely soluble in weak spirit, but may be
distinguished by its slight solubility in water, and in the ease

1 Compare Jarmerstedt, Archiv f. exp. Pathol. und Pharmacol. xi. 22, 1879
(Amer. Journ. Pharm. lii. 91).

- Loc. cif.

3Sitzl>. der Dorpater Naturf. Ges. 240, 1879; 94, 1881. Phann. Journ.
and Trans. [3], x. 909, 1013, xii. 681.

174 GLUCOSIDES OTHER THAN TANNINS.

with which it splits up into sugar and melanthigenin when boil(
with a dilute acid.

The so-called smilacin was also formerly regarded as allied
saponin, but the researches of Fliickiger1 have shown that und(
this designation a mixture of substances has been described, tl
principal constituent of which was named parillin. This bod]
stands in close relation to sapogenin, the decomposition-prodw
of saponin ; and as the latter is contained in sarsaparilla,2 it is
probable that parillin is produced from it during the life of the
plant. According to Fliickiger, 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'S3 more easily than by stronger
or weaker alcohol.3 Its reaction with cone, sulphuric 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. Eoch-
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 cone, sulphuric 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 indiglucin. 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, etc.), but to undergo a partial
decomposition when they are slowly dried, and the black or blue

1 Compare Fliickiger and Hanbury, ' Pharmacographia,' 646.

2 Otten, ' Histiol. Unters. der Sarsaparillen,' Diss. Dorpat, 1876. Otten
estimated the saponin by the methods given in § 78.

3 Archivd. Pharm. [3], x. 535, 1877 (Pharm. Journ. and Trans. [3], viii.

488).

S 1G8. OTHER BITTER PRINCIPLES. 175

colouration of the leaves produced thereby would arouse a sus-
picion 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, alcohol,
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 litter principles have not as yet been shown
to be glucosides ; but they are likewise sparingly soluble in ether,
more freely in alcohol: Antiarin,1 aristolochia-lUter,2 calendulin3
(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) ; carapinf cratwginf cusparin 7 (coloured
green by nitric acid, red by mercurous nitrate) ; qiiinovin 8 (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).

2 See Walz, Jahrb. f. Pharm. xxvi. 73. Gmelin's 'Organic Chemistry.'

3 See Stoltze, Ber. Jahrb. f. Pharm. 1820.

4 See Mettenheimer, N. Jahrb. f. Pharm. i. 341, 1870. Hesse, Ber. d. d.
chem. Ges. xi. 1542, 1878 (Journ. Chem. Soc. xxxvi. 73).

5 See Caventou, Vierteljahresschr. f. pract. Pharm. x. 422, 1861 (Amer.
Journ. Pharm. xxxi. 231).

fi See Leroy, Journ. de Chim. med. xvii. 3.

7 See Saladin, ibid. ix. 388 (Amer. Journ. Pharm. v. 346).

8 Compare Gmelin, < Handbook of Organic Chemistry.1 Staeder's method of
estimating quinovic acid in certain cinchona barks (N. Tijdschr. voor de
Pharm. in Nederl. 152, 1878) was pronounced unsatisfactory by de Vrij (ibid.
306).

176 ALOIN*.

sulphuric acid and sugar) ; cnicin1 (is said to dissolve green in cone,
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) ; geraniin,2 laducin and its allies,3
lining lupinin,5 mudarin,6 olivil,7 quercin 8 (very slightly soluble in
absolute alcohol) ; sparattospermin?

S 169. Aloins. — There is another group of non-glucosidal bitter
principles to which I should like to direct attention ; viz., that of
the dloins — 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.10

All the aloins can be obtained in yellow crystals, but show a
great disposition to form supersaturated aqueous solutions in
which, perhaps, they exist in an amorphous state and free from
water of crystallization. From such solutions the aloin can be

1 See Nativelle, Journ. de China, 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 Miiller, Archiv d. Pharm. [1], xxii. 29, 1828.

3 Compare Ludwig and Kromayer, Archiv d. Pharm. cxi. 1, 1862; also
Kromayer, 'Bitterstoffe.'

4 See Schroeder, N. Kepert. f. Pharm. x, 11, 1861.

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 Physique, iii. 105 ; and Sobrero,
N. Jahrb. f. Pharm, iii. 286, 1855.

8 See Gerber, Archiv d. Pharm. xxxiv. 167, 1831.

9 See Peckolt, Zeitschr. d. allgemeinen oester. Apoth. Ver. 133, 1878
(Pharm. Journ. and Trans. [3], ix. 162, 1878).

10 According to Treumann's researches ('Beitr. z. Kenntniss der Aloe,' Diss.
Dorpat, 1880) the following are the formulae of the various aloins (containing
water of crystallization) calculated to the same number of atoms of oxygen.
Barbadoes aloin = C48H58(X0, 6H.2O ; Cape aloin = C^H^CX,,, 6H..O ; Socotra
aloin = C45H52O20, 6H2O; Natal aloin = C45H56Oo0 ; Zanzibar aloin = C45H50020,
6-7H2O; Curacao aloin = C44H50O20, 6H2O. See also Fliickiger, Schweiz.
Wochenschr. f . Pharm. 331, 1870 ; Pharm.'journ. and Trans. [3], ii. 193, 1871.

§ 169. A LOINS. 177

gradually obtained by diffusion, but it is often long before they
deposit crystals (most easily obtained from Natal aloes). Ferric
chloride colours them, without exception, greenish-black (Natal
aloin very slowly) ; they are all gradually precipitated by basic
acetate of lead ; perchloride of platinum colours Barbadoes and
Curasao aloin by degrees red to violet, Socotra and Cape aloin
greenish-brown, Natal aloin yellowish-brown ; chloride of gold pro-
duces a more or less fine raspberry-red, passing generally into violet;
with strong hydrochloric acid, Natal aloin alone becomes violet;
mercurous nitrate colours Barbadoes and Curasao aloin reddish.
All the aloins are precipitated 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 in my ' Chemische Werthbestim-
mung starkwirkender Droguen,' that these bromine-precipitates
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
Avas 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 occurs in dried aloe-juice ; it is freely soluble in cold
1 Beitr. z. Kenntniss der Aloe, Diss. Dorpat, 1874.

12

178 ALKALOIDS.

water, and is possibly an oxyaloin. Bromine does not appear to
precipitate 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 (rutin, robinin, luteolin, etc.), and whilst referring to them
here, I will also allude to carthamin, the colouring matter of
safflower.1 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 precipitated by acids. It
dissolves in ether, and stains silk rose- or cherry-red.

ALKALOIDS.

§ 171. Colour-reactions. — The following reagents may be recom-
mended for producing colour-reactions with alkaloids : Pure
sulphuric acid ; sulphuric acid, containing a little nitric acid (1 in
200); sulphuric acid, containing O'Ol gram of molybdate of soda
in each cc. (Frohde's reagent) ; sulphuric acid and sugar ; sulphuric
acid and bichromate of potash ; nitric acid (sp. gr. 1 *3) ; cone,
hydrochloric acid ; ferric 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-
phuric acid and sugar, it is generally better to mix the alkaloid as
intimately as possible with 5 parts of sugar and add the sulphuric
acid to the mixture. Delphinoidine should be mixed with as con-
centrated a solution of sugar as possible before the addition of sul-
phuric acid. If bichromate of potash and sulphuric acid are to be
used in combination, it is advisable to dissolve the alkaloid in the
acid and drop a crystal of bichromate into the solution. Sulphuric
acid and nitrate of potash may be employed in the same way in
place of the mixed sulphuric and nitric acids. Ferric chloride
should be used in aqueous solution, and be as neutral as possible.2

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. Iviii. 357, 1846.

2 All these reactions are described at greater length in my ' Ermittel. d.
Gifte.'

171. REACTIONS.

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§§ 172, 173. SUBLIMATION, ETC. 181

§ 172. Other Tests. — For information concerning optical tests for
alkaloids, see Buignet.1 Upon polarization (§ 185), in particular,
see Hesse.2 For the absorption spectra observable in colour-re-
actions of alkaloids, see Meyer3 and Poehl.4

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 on a coverslip, to which a glass ring -J to f inch high is
cemented, and on which a second coverslip is laid. As soon as a
cloud is observed on the latter, the temperature is noted. The
sublimate is subsequently examined microscopically as to its
crystalline 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.5

The crystalline form of alkaloids has been closely investigated by
Erhard.6

§ 173. Platinum and Gold-salts. — 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 . . 31 '37

Aconitine . . 22 '06

Amanitine . . 44 '23

Berberine . . 29'16 . . IS'll

Brucine . 16 '52

1 Journ. de Pharm. et de Chim. [3], xl. 252, 1862 (Amer. Journ. Pharm.
xxiv. 140).

2 Anrial. d. Chem. und Pharm. clxxvi. 89, 1875 (Pharm. Journ. and Trans.
[3], vii. 191), and cxcii. 161, 1878. See also Oudemans, ibid, clxxxii. 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], xiii. 413, 1878.

4 Pharm. Zeitschr. f. Russland, 353, 1876.

5 Compare Helwig, ' Das Mikroskop in der Toxicologie,' Mainz ; Guy,
Pharm. Journ. and Trans. [2], viii. 718 ; ix. 10, 58, etc. ; Waddington, ibid.
[2], ix. 266, 409 ; Stoddart, ibid. 173 ; Brady, ibid. 234 ; Ell wood, ibid. [2],
x. 152 ; Ledgewick, Brit. Rev. Ixxxi. 262.

6 N. Jahrb. f. Pharm. xxv. 129, etc. ; xxvi. 9, etc., 1866. Amongst the
older works are Hiihnef eld's ' Chemie der Rechtspflege, ' Berlin, 1823;
Anderson, Chem. Centralblatt, 591, 1848 ; Taylor, ' On Poisons ;' Guy,
'Principles of Forensic Medicine;' Brand et Chaude', 'Medecine legale,*
Paris, 3858.

182

ALKALOIDS.

Double salt of

Gold.

Platinum.

Caffeine

37-02

24-58

Cinchonine

—

27-36

Cinchonidine .

—

27-87

Codeine

—

19-11

Coniine

—

29-38

Curarine

—

32-65

Delphinine

267

Delphinoidine

29-0

15-8

Emetine

—

29-7

Hyoscyamine

34-6

Morphine

.

19-52

Mxiscarine

43-01

—

Narcotine

—

15-7-15-9

Narceine

—

14-52

Nicotine

34-25

Papaverine .

—

17-82

Pilocarpine .

35-5

23-6-25-2

Piperine

.

12-7

Quinidine

40-04

27-38

Quinine

40-00

26-26

Strychnine

29-15

18-16

Thebaine

—

18-71

Theobromine .

—

25-55

Veratrine

21-01

—

§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-mercuric 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 sulphuric 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 precipitating solution to a filtered drop of the liquid
to be precipitated) 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 sufficient.

Atropine may also be estimated gravimetrically by adding

§ 174. ESTIMATION OF STRYCHNINE, ETC. 183

excess of potassio-mercuric iodide, dissolving the precipitate in
alcohol of 90 to 95 per cent., evaporating the filtered solution, and
weighing the residue, which contains 40 -9 per cent, of atropine.

For hyoseyamine the same precautions are necessary as for
atropine.1

In estimating coniine gravimetrically with potassio-mercuric
iodide, I obtained results that were far below the truth ; the
compound precipitated is somewhat freely soluble. (See also
§§ 175, 180.)

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 indirect
method of determining both alkaloids : 2

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 cc.), nearly (but not quite) neutralized with magnesia and
evaporated to a syrup in the water-bath. To the residue 2 -4
times its volume of 90 per cent, spirit is added, and after
standing, the precipitated mucilage is filtered off and washed.
The filtrate and washings are evaporated to about 30 to 50 cc.
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 chloroformic 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-mercuric iodide.
The weight of strychnine can be calculated from the expression
x = 5-566 (0-0197 xc-m) and that of brucine from ?/ = 6-566
(m — 0-0137 x c), where c is the number of cc. of reagent used and
m the weight of the mixed alkaloids. It is still better to weigh
the hydrochlorates of the alkaloids and calculate the strychnine
salt from the expression x = 6-1733 (0*02152 x c — m), and the

1 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).

2 See my 'Werthbestimmung,' 64. Compare also Pharm. Zeitschr. f. Russ-
land, 233, 1866.

184 ALKALOIDS.

!

brucine salt from ?/ = 7'1733 (m-0'01852 xc), c being the same
as in the previous expressions and m denoting the weight of the
mixed hydrochlorates.

Titration of mwphine and narcotine with potassio-mercuric iodide
serves only as a check on the weight of the alkaloids after
isolation (§§ 182, 187). The total alkaloid in opium cannot be
estimated volumetrically with that reagent.

For a method of examining ckelidonium compare § 65 and my
' Werthbestimmung,' p. 98.

The presence in cevaftilla seeds of three alkaloids, all of which
act upon potassio-mercuric 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.1 If an approximate
separation of the three alkaloids is desired, it must be remembered
that, according to the investigations of Weigelin,2 all three are re-
moved together by shaking with chloroform ; that sabadilline is
almost insoluble in ether, but is dissolved by 150 parts of Avater 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 proved3
that the calabar lean 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-mercuric iodide has only a limited value, but the
alkaloids might possibly be separated, and estimated gravimetri-
cally, as the calabarine precipitate is insoluble in alcohol whilst that
produced by physostigmine is soluble.

§ 175. Ooniine, pilocarpine, etc. — Zinoffsky has shown that
coniine can be accurately estimated by phosphomolybdic acid in
solutions free from ammoniacal salts.4 The strength of the
reagent was such that 1 cc. precipitated 0*05 gram of coniine.

1 Compare E. Masing, Archiv d. Pharm. [3], ix. 310, 1876 (Journ. Chem.
Soc. xxxii. 367).

2 Compare Weigelin, '"[Inters, iiber die Alkalo'ide der Sabadillsamen, ' Diss.
Dorpat, 1871 (Journ. Chem. Soc. xxv. 828). See also P. G. A. Masing,
4 Beitr. z. gerichtl. chem. Nachw. des Strychn ins u. Veratrins,' Diss. Dorpat,
1868.

3 Compare Archiv f. exper. Patholog. und Pharmacol, v. 401, 1876 (Pharm.
Journ. and Trans. [3], viii. 3).

4 ' Die quant. Best. d. Emetins, Aconitins und Xicotins,' Diss. Dorpat,
1872 (Pharm. Journ. and Trans. [3], iv. 442).

§ 175. ESTIMATION OF PILOCARPINE, ETC. 185

The same reagent has been employed by Poehl1 for the
gravimetric estimation of pilocarpine, but that chemist admits that
the results obtained are only approximate. By his method 10
grams of jaborandi leaves are extracted with 100 cc. of water
containing 1 per cent, of hydrochloric acid ; the infusion is
precipitated with acetate of lead, the excess of which is removed
by hydrochloric acid, and then, after filtration, phosphomolybdic
acid is added. The precipitate is collected, washed with water
containing a little hydrochloric acid, dried at 100°, and weighed.
It is said to contain 45 -66 per cent, of pilocarpine.

In estimating the alkaloid in solutions of the pure substance,
phosphomolybdic acid would probably in many cases yield better
results than potassio-mercuric iodide ; but there is a certain danger
attending its use, and that is the possibility in many cases of
ammonia and amidic compounds being precipitated with and
calculated as alkaloid. Of pilocarpine in particular it must be
observed that, according to Christensen, the composition of the
phosphomolybdic acid precipitate, as given by Poehl, requires
revision.

Phosphomolyldate of quinine (dried below 70°) contains, according
to Prescott, 27' 3 per cent, of quinine.

For cases in which phosphotungstic acid may be employed see
§177.

Attempts have also been made to estimate alkaloids by means
of tannic acid,2 by either drying the precipitate produced or
liberating the alkaloid from it with oxide of lead or other base,
drying and weighing. My objection to the former of these
two methods is that the tannates of the alkaloids are scarcely
ever constant in their composition. The latter might be adopted in
certain cases provided that the precipitated tannate is sufficiently
sparingly soluble, and that the alkaloid itself is not attacked,
as curarine is, by the oxide of lead used to decompose its tannate
(§ 64).

1 'Unters. d. Blatter des Pilocarpus officinalis,' St. Petersburg, 1877 (Year-
book of Pharm. 28, 141, 1881). See also Harnack and Meyer, Annal. d.
Chem. und Pharm. cciv. 67, 1880 (Pharm. Journ. and Trans. [3], xi. 551, 587>
608) ; and Christensen, Pharm. Zeitschr. f. llussland, xx. 1881 (Pharm. Journ.
and Trans. [3], xii. 400).

2 Compare, for instance, Lefort, Journ. de Pharm. et de Chimie, ix. 117,
241, 1869 (Pharm. Journ. and* Trans. [3], ii. 1029 ; iii. 63). See also my
' Werthbe.stimmung,' 40.

186 ALKALOIDS.

Hager1 and Hielbig2 have both experimented on the estimation
of certain alkaloids by precipitation with picric acid. I have no
doubt that in many cases very satisfactory results might be
obtained by combining precipitation by picric acid with extraction
by agitation with solvents, and in this opinion I have recently
been confirmed by experiments published by Hager on the
quantitative determination of nicotine. Hager recommends
precipitation with picric acid at a temperature of 15°, washing
with an aqueous solution of the precipitant, and finally drying at
a temperature not exceeding 40° to 50°. He found the nicotine
precipitate to contain 27 per cent, of alkaloid.

§ 176. Estimation of Caffeine. — I may supplement the method
given in § 66 for the estimation of this alkaloid by the following
remarks : Ether3 extracts the alkaloid in a state of greater
purity than chloroform, and yields therefore a correspondingly
better result ; but the mass must be very finely powdered, and
the treatment with ether repeated several times to be certain
of dissolving the whole of the caffeine. I have also used a mixture
of 3 parts of ether with 1 of chloroform with success.

In estimating the alkaloid in guarana it is not advisable to
extract with acidified water, nor is it necessary in determining the
theine in 'tea.

Lieventhal4 extracted the powdered tea directly with
chloroform, by which, however, far less than the total quantity of
theine was dissolved. I must make the same objection to Claus's
method,5 which consisted in extracting with ether, shaking the
ethereal extract with dilute sulphuric acid, neutralizing the
aqueous solution with magnesia, evaporating to dryness, and
again extracting with ether. Moreover, it would be difficult to
remove the whole of the theine from ethereal solution by shaking
with acidified water.6

1 Pharm. Centralblatt, x. 137, 145, 1871. Compare also Medin and Alnien,
Jahresb. f. Pharm. 1871.

2 Loc. at.

3 Compare Wurthner's investigations, Pharm. Zeitschr. f. Russland, 711,
1872 ; and Weyrich, ' Ein Beitr. z. Chemie des Thees und Kaffees,' Diss.
Dorpat, 1872 (Journ. Chem. Soc. xxvi. 1235).

4 Pharm. Zeitschr. f. Russland, 369, 1872 (Year-book of Pharm. 239,
1873).

5 Pharm. Zeitschr. f. Russland, 357, 565, 1862.

6 For the less recent methods of Peligot and Zb'llner, see my ' Chem.
Werthbestimmung,' 59. For other methods see Comaille, Zeitschr. f. anal.

§ 177. ESTIMATION OF THEOBliOMINE. 187

§ 177. Theobromine. — Trojanowsky found that the theobromine
in cacao-seeds might be estimated by the following process l :
5 grams of the powdered seed are freed from fat by treatment
with petroleum spirit, dried, rubbed down with powdered glass
and water to a thin paste, mixed with an equal weight of calcined
magnesia, and dried in the water-bath at 60° to 70° C. The residue
is again finely powdered, and exhausted by boiling with 80 per
cent, spirit. The decoctions are filtered whilst hot, and evaporated
to dryness in a beaker. From the dry extract petroleum spirit
will dissolve a little more fat ; after having been again dried, the
mass is thrown on to a tared filter, and washed with cold spirit
till nearly colourless. It is then dried and weighed, and to the
weight of theobromine thus obtained 0'0007 gram added for
every cc. of wash-spirit.2

Wolfram estimates theobromine in cacao-seeds by precipitating
with phosphotungstic acid3 (§ 64), and subsequently separating

Chem. xv. 474, 1876 (Year-book of Pharm. 20, 1876) ; Markownikoff, ibid,
xvi. 127, 1877 (Year-book of Pharm. 104, 1877) ; Cazeneuve and Caillol,
ibid. xvii. 221, 1878. The latter replace the magnesia in the above method
with lime, and the ether with chloroform ; Markownikoff also uses chloroform.
In working upon coffee-beans it will be found very difficult to reduce them to
the fine powder necessary to ensure the success of the estimation. This may
be best accomplished after the beans have been thoroughly dried at 100°C. ;
Weyrich, however, has shown that the amount of caffeine contained in a
sample of coffee is no criterion of its quality, and even the estimation of the
ash, potash and phosphoric acid in addition to that of the caffeine does not
furnish data free from objection. Levesie estimated (Archivd. Pharm. [3] viii.
298, 1876 ; Journ. Chem. Soc. xxxi. 752) fat, mucilage, tannin and cellulose,
but with unsatisfactory results. The determinations of the theine, substances
soluble in water, ash, etc., in tea, made by Weyrich, showed the possibility of
detecting adulterations, but not of judging of the quality.

1 ' Beitr. zur pharmacog. und chem. Kenntniss des Cacaos,' Diss. Dorpat,
1875. This work also contains estimations of the other more important con-
stituents of cacao (fat, ash, starch, etc. ) in various samples.

2 According to determinations made at my request by Treumann, theobromine
dissolves in 148'5 parts of water at 100°, and in 1,600 at 17° ; in 422*5 parts of
boiling absolute alcohol, and 4284 parts at 17°, and in 105 parts of boiling
chloroform. It differs in its solubility from caffeine, with which, however, it
shares the reaction with chlorine and ammonia. Shaking with benzene does
not remove theobromine from aqueous solutions (§ 55). See Archiv d. Pharm.
[3], xiii. 1, 1878 (Year-book of Pharm. 71, 1879). Basic acetate of lead does
not precipitate theobromine from aqueous solution.

3 Zeitschr. f. anal. Chem. xviii. 346, 1879 (Year-book of Pharm. 48, 1879).
He prepared his reagent by dissolving 100 grams of tungstate and 60 to 80
of phosphate of soda in 500 cc. of water acidulated with nitric acid. For the
use of phosphotungstic acid as an alkaloid-reagent, see also Scheibler, Journ.
f. pract. Chem. Ixxx. 211, 1866.

188 ALKALOIDS.

the alkaloid from the precipitate. Ten grams of the substance
are rubbed down with water to a fine paste, then exhausted by
boiling with the same menstruum, filtered and washed with
boiling water (700 to 800 cc.), as long as alkaloid can be detected
in the washings. The mixed aqueous solutions are precipitated
with ammoniacal acetate of lead and filtered. The filtrate is made
alkaline with caustic soda, evaporated to 50 cc., acidified with
sulphuric acid, and again filtered. From the acid solution, which
should contain about 6 per cent, of free sulphuric acid, the theo-
bromine may be precipitated by warming with phosphomolybdic
acid. The precipitate is collected when cool, washed with water
acidified with sulphuric acid, and decomposed by warming with
caustic baryta ; the excess of the latter is removed by sulphuric acid
and the sulphuric acid by carbonate of barium. The mixture is
then filtered whilst hot, evaporated to dryness, and weighed. By
deducting the ash the amount of pure theobromine is found.

§ 178. Estimation of Piperine. — The following is Cazeneuve
and Caillot's method:1 10 grams of finely-ground pepper are
mixed with 20 of slaked lime, and enough water to form a thin
paste, boiled for fifteen minutes, and then evaporated to dryness
on a water-bath ; the residue is finely powdered and exhausted with
ether. The pipeline obtained by evaporating the ethereal solution
is recrystallized from alcohol and weighed. It would, I think, be
better if the powdered pepper were first freed from fat by treat-
ment with petroleum spirit. Possibly the alkaloid might then be
purified by washing with petroleum spirit and water instead of
recrystallizing from alcohol. (Compare also § 64.)

§ 179. Addimetric Estimation of Nicotine. — Schloessing's process,
mentioned in § 68, consists in extracting the nicotine by passing
the vapour of ether and ammonia through the tobacco, condensing
the distillate, allowing the ether and ammonia to evaporate, and
titrating the residual nicotine with dilute sulphuric acid. But
the alkaloid retains ammonia, and the amount found is conse-
quently too high. (Compare Kosutany and my ' Werthbestim-
mung.')

Wittstein, Brandl, and Liecke, all extract the tobacco with
water acidified with sulphuric acid. Liecke evaporates to a
syrup, precipitates with 2 volumes of alcohol, washes, and again
evaporates. The residue is made alkaline with excess of potash,

1 Zeitschr. f. anal. Chem. xvii. 379, 1878 (Year-book of Pharm. 42, 1878).

§§ 180, 181. SEPARATION BY PRECIPITATION. 189

and distilled (finally at a temperature of 260°) into a measured
quantity of volumetric sulphuric acid, the excess of which is then
determined by solution of soda. Wittstein and Brandl distil the
acid extract direct with caustic potash, and note the amount of
sulphuric acid necessary to neutralize the distillate. They then
evaporate to dryness, extract with alcohol, which dissolves the
sulphate of nicotine, and determine the sulphuric acid in the
insoluble portion. This is then deducted from the quantity used,
and from the difference the nicotine present is calculated.

Kosutany treats the leaves, previously soaked in water, with
milk of lime until free from ammonia, then extracts with water,
and shakes the filtered solution with petroleum spirit. From the
latter, after separation, the alkaloid is removed by agitating with
a known quantity of volumetric sulphuric acid, the excess of
which is determined by baryta water. (Compare my ' Werthbe-
stimmung,' p. 55.)

§ 180. Coniine. — Similar methods have also been proposed for
the estimation of coniine. I have already expressed my opinion
of them in my ' Werthbestimmung,' p. 42, where I have at the
same time pointed out that those processes which involve the
evaporation of a solution of chloride of coniine, and determination
of the alkaloid from the amount of chlorine in the residue,1 are
open to objection on the ground that chloride of coniine is easily
volatilized (§§ 174, 65).

§ 181. Separation of two Alkaloids. — Attention has already been
drawn in § 69 to cases of the occurrence of two alkaloids in
vegetable substances. The remarks made in that section may be
supplemented here with a few examples so taken as to include
details of processes of more frequent applicability, and to give
hints for the valuation of drugs in general use. Some such
instances have already been described in § 174, and I propose
following these here with the discussion of a few more methods
for the separation of only two alkaloids.

Let us first assume that the two alkaloids td*be separated dij/'cr
in their behaviour to acids, as, for instance, jervine and veratro'idutct
alkaloids that occur in Veratrum album, lobelianum and viride.-

1 Compare Hager, ' Untersuchungen,' ii. 250.

2 See Tobien. ' Beitr. z. Kenntniss cler Veratrum Alkaloide,' Diss. Dorpat,
1877 (Pharm. Journ. and Trans. [3], viii. 808) ; Bullock, Amer. Journ. Pharm.
xlvii. 451, and xlix. 453 ; Wormley, ibid, xlviii. 4.

190 ALKALOIDS.

Supposing, then, both these alkaloids to have been extracted
together by shaking with chloroform, and to have been redis-
solved in dilute (2 per cent.) acetic acid, the addition of dilute
sulphuric acid to such a solution would cause the precipitation of
the majority of the jervine as sparingly soluble acid sulphate
(Simon's vegetable baryta). According to Bullock this salt
requires 427 parts of cold water for solution, and the precipitate
contains 15 -5 per cent, of sulphuric acid (H2S04). The hydro-
chloric acid precipitate (6 '55 per cent. HC1) is more soluble; the
most advantageous method 'oi all is to precipitate nitrate of jervine
(soluble in 1,200 parts of cold water) by adding nitrate of
potassium to acetic acid solution. Veratroidine remains in the
filtrate, from which it can be extracted by shaking with chloro-
form. In a similar manner paricine may be separated from other
cinchona alkaloids in the form of a sparingly soluble nitrate.

The behaviour of two alkaloids to bases will more frequently be
found to present differences, of which advantage may be taken.
Here two cases are to be distinguished : viz., either one alkaloid
is precipitated, and the other left in solution ; or, both are pre-
cipitated, but one is redissolVed by an excess of the precipitant,
whilst the other is not. As an instance of the first of these two
cases, the separation of narcotine from narceine may be cited ; the
former is almost completely precipitated by ammonia, whereas the
narceine remains in solution. Morphine and codeine serve to
exemplify the second case, which is of more frequent occurrence ;
excess of ammonia precipitates the former tolerably completely,
but the codeine remains dissolved in the filtrate, from which it
may be extracted by shaking with benzene. On the other hand,
an excess of lime-water causes the separation of narcotine, but
does not precipitate morphine. But nearly the whole of the
latter alkaloid is thrown down if chloride of ammonium be added
to the solution in caustic lime (§ 187).

This method of precipitation with excess of alkali is, however,
unreliable in some cases, in which favourable results might have
been anticipated. Strychnine can be separated from an acid
solution very satisfactorily by the addition of excess of ammonia ;
brucine under the same conditions remains in solution until the
greater part of the ammonia has volatilized. But if both alkaloids
are present together, part of the brucine will separate with the
strychnine on the addition of ammonia.1

1 See my 'Ermittelung von Giften,' 2nd edition, 259.

§ 192. SEPARATION BY SOLVENTS. 191

Carbonated alkalies may occasionally be used instead of caustic.
For the separation of some alkaloids bicarbonates have also been
recommended, as it was found that under certain conditions one
alkaloid would form a soluble carbonate, whilst the other was
immediately precipitated in the free state. In this way paricine can
be separated from the other bark alkaloids by bicarbonate of soda.

§ 182. Behaviour to solvents. — Separation may be accomplished in
this way, either by treating the dry alkaloids with the solvent, or
by shaking it with the liquid containing the alkaloids in solution.

An instance of the first case may be found in the separation of
brucine and strychnine from a mixture of the two alkaloids pre-
cipitated by ammonia. Absolute alcohol dissolves brucine with
tolerable facility, but takes up only a minute proportion of strych-
nine.1 Another method, which I formerly employed for the
separation of these two alkaloids, may also find a place here. It
consisted in allowing the benzene solution of the mixed alkaloids
to evaporate until the majority of the strychnine had separated,
then quickly pouring off the mother liquor, washing with benzene,
and evaporating to dryness ; the brucine was thus obtained, mixed
with a little strychnine (0'0683 gr. for every cc.). I have suc-
ceeded in separating the two alkaloids tolerably completely by
both of these methods, but as they occasionally fail I cannot
further recommend either of them ; the first is, however, the
more preferable of the two.

By treatment with water cokhicine may be separated from the
colchiceine, which sometimes accompanies it in colchicum corms.
The quantity of solvent used must not, however, be too small, as
colchiceine is more soluble in concentrated aqueous solutions of
colchicine than in pure water, which dissolves it but very
sparingly.2

Moens,3 Stoeder,4 and Hielbig,5 found 40 per cent, spirit
adapted for the separation of the cinchonine and ' amorphous

1 Compare my ' Werthbestimmung, ' 66. Even if the greater part of the
free ammonia present be allowed to evaporate, the complete precipitation of
brucine is a matter of difficulty ; that portion of the alkaloid that remains in
solution must therefore be removed by shaking with benzene.

2 See Hertel, Pharm. Zeitschr. f. Kussland, Nos. 13 to 18, 1881 (Pharm.
Journ. and Trans. [3], xii. 498).

3 Nieuw Tijdschrift voor de Pharm. in Nederl., 322, 1869 ; 7, 1870 ; 161,
1875.

4 Archiv d. Pharm. [3], xiii. 243, 1878 (Journ. Chem. Soc. xxxvi. 281).

5 Kritische Beurth. der Method, zur Trennung und quant. B?st. d. China-
alkaloide,' Diss. Dorpat, 1380.

192

ALKALOIDS.

alkaloid ' of cinchona bark. The latter found 1 part of cincho-
nine dissolve in 1,100 parts of spirit of that strength, but, as the
solution obtained in the separation of the alkaloids is not a
saturated one, he recommends the addition of 0*0002 gram
cinchonine for every cc. of such spirit used. He also found pure
ether (free from water and alcohol) very suitable for the same
purpose, as it dissolves so little cinchonine that a correction is
scarcely necessary. The mixture of both alkaloids must be com-
pletely dried in the water-bath, and then very carefully powdered.
The separation of two alkaloids by means of ether may also be
accomplished by allowing the ethereal solution of both to evaporate

Fig. 8.

gradually, and, if one should separate in crystals, removing the
other by slow washing with ether in the form of vapour. By this
method I succeeded with Marquis l in separating delphinine from
delphindidine in perfectly colourless crystals.

The flask «, containing the mixed alkaloids (Fig. 8, A), was
inverted in the wide-mouthed bottle, b, into which about 10 cc.
of pure ether had been poured. The apparatus was then allowed
to stand for several days at the ordinary temperature, during
which ether-vapour from 5 was continually condensing in a, and
dropping back into b} saturated with delphinoidine.

The apparatus figured in 8 B, allows of the process being, to a
certain extent, regulated ; the funnel a, containing the flask, can
be raised or lowered at pleasure.

1 Archiv f. exper. Pathol. iind Pharmacol. vii. 55, 1877.

§ 183. SEPARATION BY PRECIPITATION. 193

For the separation of morphine from narcotine by ether, see
§ 187. Ether and chloroform (free from alcohol) can also be
used to separate the former from codeine and thebaine. Morphine
can be separated from thebaine, codeine, and narcotine, by the
method of agitation; the last three are removed by benzene
from ammoniacal solution, whilst scarcely traces of morphine are
dissolved.

In a similar manner delphinine and delphino'idine may be sepa-
rated from staphisagrine by agitation with ether, in which the
latter is insoluble ;x after removing the first two, staphisagrine
may be extracted with chloroform.

§ 183. Use of Salts, etc. ; Separation of Quinine and Cinchonidine,
etc.2 — Instances of the use of salts in the separation of alkaloids
may be found in the employment of tartrates for the quantitative
estimation of quinine and cinchonidine in the presence of quinidine
and cinchonine (cf. § 184, I.) ; by means of iodide of potassium or
sodium, quinidine can be separated from cinchonine and * amorphous
alkaloid ' (cf. § 184, IV.). Wittstein recommended conversion into
oxalates in alcoholic solution for separating strychnine and brucine;*
quinine may be freed from cinchonidine by precipitation as hera-
pathite* (ci. § 184, II.).

The separation of calabarine from physostigmine by potassio-
mercuric iodide, has already been described in § 174 ; the same
method might perhaps be feasible with chelidonine and sanguinarine.5

Chloride of gold can be used in separating muscarine from
amanitine, as the double salt of the former is more soluble in
water than that of the latter.6

Perchloride of platinum was the salt used in separating paytine
from the other bark alkaloids, as the double salt of platinum with
that alkaloid is very sparingly soluble in water. By means of the
same salt, ammonia may be separated from those alkaloids and
amides that yield double salts of greater solubility (§ 98). It
must, however, be borne in mind that certain alkaloids undergo

1 See the paper by Marquis and myself previously quoted.

2 Comp. Moens, loc. cit.; Johanson, Archiv d. Phann. x. 418, 1877 ;
Hielbig, loc. cit.

3 Vierteljahresschrift f. pract. Pharm. viii. 409, 1859.

4 Compare Herapath, Pharm. Journ. and Trans. [1], xi. 448 ; xii. 6 ; de
Vrij [3], vi. 461 ; N. Tijdschr. voor de Pharm. 1881 ; Hielbig, loc. cit.

5 See my ' Chem. Werthbestimmung, ' 102.

6 Compare Harnack, Archiv f. exper. Pathol. und Pharmacol. iv. 82, 1875.

13

194 ALKALOIDS.

rapid decomposition when precipitated in combination with
chloride of gold and platinum (e.g. curarine).

§ 184. Quantitative Separation of Several Alkaloids from one
another. — Such cases occur in the examination of cinchona barks.
Although several of the many alkaloids in these barks are present
in such minute quantities that they may generally be neglected,
there are at least five the detection and estimation of which are
of importance in valuing samples. These are quinine, cinchonidine,
quinidine, cinchonine, and the so-called amorphous alkaloid. The
mixed alkaloids are extracted and estimated as directed in § 67.
For their quantitative separation from one another, I propose
using Moens' method, which has been recognised by Hielbig, after
numerous experiments, as suitable for the purpose.1

I. The mixed alkaloids just referred to are dissolved in acetic
acid,2 without the application of heat, and the solution evaporated to
dryness, care being taken that the residue does not turn brown.
This is then dissolved in the smallest possible quantity of water
and filtered. From the solution, which should not be evaporated,
quinine and cinchonidine are precipitated together by (about -5
of a gram of) tartrate of ammonia and soda, which is preferable
to the Rochelle salt usually used. After standing twenty-four
hours the precipitate is filtered off, washed, dried at 110°, and
weighed. 1-6 gram of mixed alkaloids would yield about 30 cc.
of filtrate, and require about the same quantity of wash-water.
A correction must be made of 0 '000746 gram of quinine and
0 '000441 gram of cinchonidine for each cc. of filtrate and wash-
ings, provided that both alkaloids are present together. If the
bark contains quinine alone, 0*00102 gram must be added for each
cc. ; or if cinchonidine alone, 0 '000543 gram. The apparent dis-
crepancy in these figures is caused by the influence exercised by
the presence of either tartrate on the solubility of the other. 100
parts of precipitate indicate 79*41 anhydrous quinine or 76 '8
cinchonidine.

II. To separate quinine from cinchonidine the mixed tartrates
are dissolved in 90 to 92 per cent, spirit containing 1 *6 per cent.

1 Loc. cit.

2 Hielbig has also experimented with hydrochloric and tartaric acids, but
obtained the best results with acetic. The chlorides formed by the hydro-
chloric acid appear specially liable to cause errors when subsequently precipi-
tating with tartrate. Whichever acid, however, be chosen, the excess must
in some way be removed.

§ 184. ESTIMATION OF CINCHONA-ALKALOIDS. 195

of sulphuric acid ; the filter used in the previous operation is also
extracted with spirit of the same strength. One part of precipi-
tate should yield about 20 parts of solution ; from this the quinine
is best precipitated by the reagent recommended by de Vrij,1
which is prepared as follows : To a solution of 2 parts of sul-
phate of quinoidine in 8 of 5 per cent, aqueous sulphuric acid,
a solution of 1 part of iodine and 2 of iodide of potassium in 100
of water is gradually added with constant stirring. The flocculent
precipitate thus produced is slightly warmed till it agglomerates
into a resinous mass, which is then washed with warm water,
dried, and dissolved with application of heat in 6 parts of 92 to 94
per cent, spirit. After cooling the liquid is filtered off and
evaporated to dryness, the residue redissolved in 5 parts of spirit,
again filtered, and the filtrate used as the reagent. During the
precipitation of the herapathite with this reagent, the liquid must
be vigorously stirred to prevent the partial separation of cinchoni-
dine in the form of orange flocks. If that has taken place the
mixture must be warmed until the precipitate disappears. Accord-
ing to de Vrij, sufficient of the reagent has been added when an
intense yellow colouration makes its appearance in place of a
green precipitate of herapathite ; the mixture is then heated to
incipient ebullition, cooled, and its weight ascertained to allow of
a correction for dissolved herapathite being subsequently made.
Finally, the precipitate is collected on the filter previously used
in separating the tartrates and washed with a saturated alcoholic
solution of quinine-herapathite. After draining, the funnel is
weighed with the filter, dried, and again weighed ; the difference
is the amount of herapathite solution retained by it, for each
gram of which, as well as of mother liquor (not washings), a
correction must be made of 0*00125 gram of quinine. 100 parts
of herapathite dried at 100° indicate 58*22 of anhydrous quinine.
To ensure the success of the experiment, it is absolutely necessary
that the herapathite should separate in the form of green glitter-
ing crystals, as otherwise the solubility differs from that here
stated; amorphous herapathite, as well as some of the quinine
compounds richer in iodine prepared by Jorgensen, are far more
easily soluble. Unfortunately it sometimes happens, when work-
ing upon the mixed alkaloids separated from bark, that it is
impossible to obtain the precipitate in this crystalline condition even

1 Loc. cit.

13—2

196 ALKALOIDS.

after three or four days. In this case a different correction must
be made from that above mentioned, viz. 1 in 465, as determined
by Hielbig, instead of 1 in 600. It is more advantageous to sepa-
rate the quinine from the greater part of the cinchonidine by
ether, then precipitate in the cold and filter off at once.1

III. The amount of quinine thus found is calculated into
tartrate, and deducted from the weight of the mixed tartrates
determined in I. ; from the difference the amount of cinchonidine
present can be calculated.

IV. The filtrate and washings from the tartrate-precipitate are
mixed with iodide of sodium (in the proportion of 0'5 gram for
each gram of mixed alkaloids), evaporated to 20 cc. cooled, and then
vigorously stirred. After standing twenty-four hours, the iodide of
quinidine, etc., that has separated, is collected on a small tared
filter, transferred to a small beaker, and triturated with 10 cc. of
95 per cent, spirit, returned to the same filter, and again treated
with the same quantity of spirit. The residue is finally washed
with 20 cc. of water,2 dried and weighed. 100 parts of precipi-
tate correspond to 71*68 parts of anhydrous quinidine, to which
a correction of 0'002481 gram has to be added for each cc. of
filtrate and washings.

V. To the filtrate and washings from the last operation hydro-
chloric acid is added until perfectly clear, then considerable excess
(2 to 3 grams) of carbonate of soda, and the mixture evaporated to
dryness on the water-bath. The residue is reduced to the finest
possible powder, transferred to a small dry flask, and extracted by
maceration with pure ether, in successive portions of 10 to 20 cc.
each, as long as any colour is removed. The ethereal filtrates
are evaporated, the residue dried and weighed as amorphous
alkaloid after deducting the quinine that has escaped precipitation
as tartrate.

VI. The portion insoluble in ether is freed from that liquid by
warming, and treated with water to remove soda, etc. ; the cin-
chonine is then filtered off, washed, dried at 110°, and weighed.
Traces of that alkaloid adhering to the filter used in filtering the
ethereal solution and to the sides of the flask, may be dissolved

1 Compare Christensen, Pharm. Zeitschr. f. Russland, 1881 (Pharm. Journ.
and Trans. [3], xii. 441 ; de Vrij, ibid. 601).

2 The object of washing with spirit is to redissolve any iodide of cinchonine
or amorphous alkaloid that may have separated out. It is important that the
relative proportions of liquid, wash-spirit, and wash-water should be observed.

§ 184. ESTIMATION OF CINCHONA-ALKALOIDS. 197

in hydrochloric acid, added to the aqueous filtrate containing
soda, etc., and removed from solution by shaking with chloroform.
The alkaloid thus isolated must be weighed and added to the
amount previously found, from which sum, however, the cin-
chonidine and quinidine left in solution must be deducted if great
accuracy is required.

Hielbig also describes a second process for determining quinidine,
cinchonine, and amorphous alkaloid, as follows :

VII. The filtrate and washings from the precipitated tartrates
are evaporated to 20 cc., and for each gram of mixed alkaloids
0'5 gram of iodide of sodium, dissolved in 5 cc. of water and 15
of 90 per cent, spirit, is added, and the whole allowed to stand
for twenty-four hours in a cool place. The iodide of quinidine is
then collected on a tared filter, washed with a little water, dried at
100°, and weighed. (No correction is necessary for the alkaloid
left in solution.)

VIII. The filtrate from the last operation is treated as in V.,
but the precipitate produced by the soda solution is here filtered
off and the alkaloid still retained by the liquid extracted by
shaking with chloroform. Both portions are then transferred to
a beaker, and macerated with 40 per cent, spirit to remove
amorphous alkaloid. It is best to cool the mixture and agitate,
repeating the treatment as long as the spirit becomes coloured.
The cinchonine is finally filtered off, dried, and weighed, 0*000202
gram being added for each cc. of spirit used.

IX. The alcoholic solutions are evaporated to dryness at 110°,
and from the weight of the residue the quinine, cinchonidine, and
cinchonine, previously reckoned as 'correction,' deducted. The
remainder is to be regarded as amorphous alkaloid.

If the bark contain so little quinine and cinchonidine that
after the addition of tartrate only single crystals are deposited on
the sides of the beaker where touched by the glass rod, in quan-
tity too small to allow of their being weighed, it may be assumed
that the liquid contains at least the amount of alkaloid equal to
the correction to be made. The actual presence of quinine may
be detected by the thalleioquin reaction (§ 171) : if that yield a
positive result, the presence of cinchonidine must remain a matter
for conjecture ; but if the result be negative, the precipitate may
be assumed to consist of cinchonidine, and its quantity calculated
from the correction to be made.

198 ALKALOIDS.

The same course may be pursued when only traces of quinidine
are precipitated.

§ 185. Behaviour to Polarized Light. — Attempts have also been
made in examining barks to take advantage of the differences
the alkaloids show in their behaviour towards polarized light, but
the requisite accuracy does not seem to have been yet attained.1
In working with mixtures of the pure alkaloids, the results are,
it is true, very satisfactory ; but as soon as the mixed alkaloids
separated from barks are examined the errors increase, as even
small quantities of contaminating impurity can exercise a con-
siderable influence on their action on a ray of light.

The most feasible is Oudemans' method of estimating quinine
and dnchonidine. The alkaloids are precipitated as tartrates, and
redissolved in hydrochloric acid (to 0*4 gram precipitate about
3 cc. normal acid, and water to 20 cc. ). Such a solution of quinine
shows a rotation [a]D - - 215-8°; of cinchonidine [«]D= - 131 '3°.
The calculations may therefore be made according to the formula :

215-8z + 131 -3(100 -x) = lW(a)m

where x is the percentage of tartrate of quinine, and (a)m the
specific rotatory power of the mixture.

§ 186. Other Cinchona Alkaloids. — The following are some of the
cinchona alkaloids of less frequent occurrence :

Aricine,2 the sulphate of which swells up to a jelly in chloro-
form.

Cusconine,B the neutral sulphate of which gelatinizes in aqueous
solution, and does not dissolve in more sulphuric acid. Acetate
of cusconine is also gelatinous.

Quinamine* This alkaloid occurs notably in Cinchona succirubra,
and generally remains associated with the * amorphous alkaloid '

1 Compare the papers quoted in § 172 by Oudemans, Hesse and Hielbig.
For the application of fluorescence, see Kerner, Zeitschr. f. anal. Chemie, ix.
135, 1870.

2 Compare Hesse, Annal. d. Chem. und Pharm. clxxxi. 58, 1876 (Pharm.
Journ. and Trans. [3], vii. 331, 1876).

3 See Hesse, Ber. d. d. chem. Ges. ix. 742, 1876 (Year-book Pharm. 226,
1880).

4 Compare Hesse, Ber. d. d. chem. Ges. x. 2152, 1877 (Year-book Pharm.
62, 1878) ; Annal. d. Chem. und Pharm. cxcix. 333, 1880 (Year-book Pharm.
34, 1880) ; de Vrij, N. Tijdschr. voor de Pharm. en Nederl. 69, 1877.
Oudemans, Annal. d. Chem. und Pharm. cxcviii. 135, 1879 (Year-book
Pharm. 57, 1879; 34, 1880).

§ 187. ESTIMATION OF MORPHINE. 199

isolated in the examination of the bark. It may be separated as
follows : The mixed alkaloids are dissolved in dilute acetic acid,
and to the solution sulphocyanide of potassium is added until the
colour is only pale yellow. After standing till perfectly clear it
is filtered, the filtrate made alkaline with ammonia and shaken
with ether. The residue obtained by evaporating the ethereal
solution is then recrystallized from alcohol. Quinamine dissolves
in 32 parts of ether, and is also soluble in boiling petroleum
spirit. The precipitate produced with chloride of gold rapidly
decomposes with production of a red colouration.

For paricine, see § 181 ; paytine, §§ 183, 189. Hesse states
of the latter that it is coloured purplish-red by chloride of gold,
and red passing to blue by chlorinated lime.

For other cinchona alkaloids, see Hesse in the papers, etc.,
already quoted.1

§ 187. Estimation of Opium. — Many methods have already been
proposed for the estimation of the more important opium alkaloids.
I have criticized them at length in my * Chemische Werthbestim-
mung/ and restrict myself, therefore, here to recapitulating the
modification of the Guibourt-Schacht's process there recommended,
adding a few remarks on methods that have appeared since the
publication of that work.

I. Five to ten grams of powdered opium are triturated with
water to a very thin paste, macerated twenty-four hours and
filtered. The residue is again treated in the same manner, and
finally washed on the filter until the washings are colourless.
When dried the insoluble portion should not amount to more
than 40 per cent, of the opium employed. It still contains nar-
cotine, which may be estimated according to VI.

II. The aqueous infusions and washings are evaporated in the
water-bath until reduced to about five times the weight of the
opium employed, cooled, filtered if necessary, and mixed with the
slightest possible excess of ammonia. 2 It is then vigorously stirred,

1 Compare also Ber. d. d. chem. Ges. xi. 1938, 1878 (Pharm. Journ. and
Trans. |3], xi. 839, 1881) ; Annal. d. Chem. und Pharm. ccv. 194, 211, 1880
(Year-book Pharm. 24, 27, 28, 1879 ; 42-44, 1881).

2 See Cleaver, Amer. Journ. Pharm. xlviii. 359, 1876 (Pharm. Journ. and
Trans. [3], vii. 240), and my remarks in the Jahresb. f. Pharm. 175, 1876.
Cleaver, who also employs a modification of Mohr's process, recommends the
opium to be previously exhausted with bisulphide of carbon, which removes
substances that interfere with the subsequent operations.

200 ALKALOIDS.

and allowed to stand exposed to the air, with occasional agitation,
until the excess of ammonia has disappeared (not longer). The
precipitated mixture of morphine, narcotine, and meconate of
calcium is filtered off and dried. It should amount to not less
than 14 per cent, of the opium used. Filtrate and washings are
treated according to V.

III. The precipitate is removed from the filter, reduced to the
finest possible powder, and macerated with pure ether in a dry
flask as long as narcotine is removed. The ethereal solutions are
filtered through the same filter, evaporated to dryness at 110°,
and weighed, or instead of weighing the residue may be dissolved
in water acidulated with sulphuric acid, and titrated with potassio-
mercuric iodide (§ 65). The weight is noted as the amount of
narcotine soluble in water.

IV. The residue insoluble in ether is dried and exhausted with
boiling alcohol of specific gravity 0*81, which removes morphine,
and leaves meconate of calcium undissolved. The alcoholic solu-
tions are filtered through the filter already used in the extraction
with ether. The weight of the alkaloid can be ascertained either
by evaporating to dryness, redissolving in acidulated water, pre-
cipitating with ammonia, and weighing, or by evaporating, redis-
solving in dilute sulphuric acid, and titrating according to § 65.
Good opium contains at least 8 per cent, of morphine.

V. If the morphine is reprecipitated for gravimetric estimation
the filtrate may be mixed with the filtrate from II., made alkaline
with ammonia, and shaken with amylic alcohol. All the morphine
in solution is thus removed, and the amount which escapes precipi-
tation in II. is sometimes very considerable. The amylic-alcohol
solutions are evaporated to dryness, the residue dissolved in a
little acidulated water, precipitated with a slight excess of
ammonia, dried, weighed, and noted as morphine. A correction
of O'OOl gram for each cc. of mother-liquid may be made if
desirable.

VI. If the sample under examination is an opium of good
quality the insoluble residue from I. will contain narcotine, but
no morphine. The former may be estimated by extracting with
water acidulated with sulphuric acid, precipitating with ammonia,
filtering, washing, redissolving in dilute sulphuric acid, and
titrating with potassio-mercuric iodide (§ 65).

§ 188. Other Methods. — Weak spirit was also formerly employed

§ 189. RARER ALKALOIDS. 201

in the place of water for exhausting the opium, and Proctor1 has
recently proposed triturating the opium (13 grams) with water
(15-5 gram) to a paste in a warm mortar, adding methylated
spirit (46 grams) by degrees, and exhausting by percolation with
the latter menstruum. The solution is evaporated to a syrup,
mixed with water (63 grams), and filtered. The filtrate is again
evaporated (to 6 cc.), mixed with an equal volume of methylated
spirit and slight excess of ammonia, allowed to stand twelve to
eighteen hours, filtered and the precipitate washed, first with a
mixture of equal quantities of methylated spirit and water, and
finally with the latter alone (about 31 grams). Proctor removes
narcotine with benzene.

For the approximate estimation of the morphine Prollius
recommends extracting the opium with 10 parts of 34 per cent,
spirit, mixing the solution with 5 parts of ether and 0'2 of
ammonia, allowing to stand twelve to twenty-four hours, filtering
off, drying and weighing the morphine, which separates at the
line of demarcation; narcotine is said to be dissolved by the
ether.

Fliickiger2 exhausts 8 grams of powdered opium by agitation
for twelve hours with 80 grams of water, and filters the infusion
through a filter 125 mm. in diameter. 42 -5 grams of the filtrate
are mixed with 12 grams of alcohol of sp. gr. 0*812, 10 grams of
ether, and 1 *5 caustic ammonia in a tared flask, and set aside for
a day or two. The crystals of morphine that have separated are
then collected on a double filter 4 inches in diameter; both flask and
residue on the filter are washed, first with a mixture of 6 grams
of spirit with 5 of ether, and afterwards with 10 grams of ether.
The crystals are finally gently pressed, returned to the flask, dried,
and weighed. To the amount thus obtained Fliickiger adds 01
gram (Mylius 0'088) for loss in precipitating and washing.

For the rotatory power of opium alkaloids, see Hesse.3

§ 189. Other Alkaloids. — In treating of the more important

1 Pharm. Journ. and Trans. [3], vii. 244, 1876 ; viii. 211, 1877.

2 Pharm. Zeitung, Nos. 57, 59, 1879 (Pharm. Journ. and Trans. [3], x. 254,
1879). See also Van der Burg, Pharm. Weekbl. No. 26, 1879 ; Mylius,
Archiv d. Pharm. [3], xv. 310, 1879 (Year-book Pharm. 22, 23, 1880).

3 Annal. d. Chem. und Pharm. clxxvi. 189, 1875. See also Yvon, Journ.
de Pharm. et de Chim. xxix. 372, 445, 1879. A paper on the rarer opium
alkaloids was published by Hesse in the Annal. d. Chem. und Pharm. cliii.
47, 1870 (Pharm. Journ. and Trans. [3], i. 205, 1870).

202 ALKALOIDS.

alkaloids, I have described such of their properties only as are of
importance for the object of this work, and refer students that
may desire more minute details to any good text- or hand-book of
chemistry. I may be permitted to give a few literary references,
and make a few observations on some of the alkaloids with which
we are less familiar, and about which little or no information is
to be found in text- or hand-books, in case it should be necessary
in the course of an analysis to compare a substance with any one
of them.

For ergotinine and picrosderotine, compare Tanret1 and Blum-
berg.2 Two volumes of cone, sulphuric acid colour an aqueous
solution of the former, first red, then bluish-violet, of the latter
violet. With an equal volume of Frohde's reagent, both are
coloured violet, passing to blue. Both can be extracted from
solution by agitation with ether. The latter, which is resinous
and very sparingly soluble in water, is possibly a decomposition-
product of the former.

For curarine, which is freely soluble in water, see Preyer3 and
Sachs.4 This alkaloid cannot be removed from solution by shak-
ing with ether, etc. Its reactions are described in § L71. Chloro-
form extracts small quantities (sufficient for the reactions and
physiological experiments) of the alkaloid from the residue
(finely powdered) obtained by evaporating its aqueous solution.
(Compare also §§ 64, 68, 182.)

For erythrophlceine see Gallois and Hardy.5 It is soluble in
water, can be extracted by shaking with acetic ether, and is
coloured violet by sulphuric acid and permanganate of potassium.

Lobeliine, see Lewis and Eichardson.6 (Cf. § 56.)

1 Repert. de Pharm. N. Se"r. iii. 308, 1875 ; v. 226, 1877 (Pharm. Journ.
and Trans. [3], vii. 249. 1876 ; vi. 522, 1875).

2 Ein. Beitr. z. Kenntniss d. Mutterkornalk. Diss. Dorpat, 1878 (Pharm.
Journ. and Trans. [3], ix. 23).

3 Zeitschr. f. Chem. vi. 382, Compt. rend. 1. 1828, 1865. See also Koch,
' Vers. liber die Nachweisbarkeit d. Curarins in thier. Fliissigk. und Geweben, '
Diss. Dorpat, 1870, and my 'Beitr. z. gerichtl. Chem.' 170, St. Petersburg,
1871.

4 Annal. d. Chem. u. Pharm., cxci. 254, 1878 (Journ. Chem. Soc. xxxiv.
517). See also my observations in the Jahresb. f. Pharm. for the same year.

5 Union Pharm. xvii. 202, 1876 (Pharm. Journ. and Trans. [3], vii. 77,
1876), also xix. 359, 1878.

6 Amer. Journ. Pharm. 293, 1872 ; Pharm. Journ. and Trans. [3], viii. 561,
1878. See also my 'Beitr. z. gerichtl. Chem.' 18.

§ 189. RARER ALKALOIDS. 203

Conessine or wrigMne, see Haines1 and Stenhouse.2 It is very
sparingly soluble in alcohol, ether, and bisulphide of carbon.

Harmaline and harmine, compare Fritsche.3 The former yields
yellow salts with acids — the latter colourless. Both are some-
what sparingly soluble in alcohol.

Surinamine is also sparingly soluble in spirit. (Compare Hiitten-
schmidt and Winkler.4)

Aribine, see Rieth.5 It is sparingly soluble in ether, as is also

Atherospermine, compare Zeyer ;° and Rhceadine, compare Hesse.7
The latter is colourless, but is converted by dilute acids into
deep red rhoeagenine.

Fioline, compare Boullay;8 for beberine, see Maclagan9 (cf. § 171);
for belladonnine, see Hiibschman j10 for cocaine and hygrine, compare
Niemann, Wohler, and Lessen.11 Concentrated hydrochloric acid
decomposes cocaine into benzoic acid, and the alkaloidal ecgonine.

For chlorogenine and porphyrine see Hesse.12 Chlorogenine in
acid solution shows a powerful blue fluorescence.

Corydaline, compare Wackenroder, Miiller and Leube, Boedecker
and Wicke.13 The alkaloid dissolves in cone, sulphuric acid, with
dark red colouration.

Cytisine, compare Husemann and Marme.14

1 Pharm. Journ. and Trans. [2], vi. 432.

2 Ibid. [2], v. 493 ; Schweizerische Wochenschrift f. Pharm. 172, 174,
1865.

3Chem. Centralblatt, 1847-49, 1853, 1854. See also Goebel, Anrial. d.
Chem. und Pharm. xxxviii. 363, 1841.

4 Gmelin's ' Handbook of Chemistry.'

5 Chem. Centralblatt, 903, 1861 (Amer. Journ. Pharm. xxxiv. 395).

6 Vierteljahresschr. f. pract. Pharm. x. 513. 1861 (Amer. Journ. Pharm.
xxxiv. 166, xxxv. 453).

7 Annal. d. Chem. und Pharm. (Suppl.) iv. 50 ; cxl. 145, 1866 ; cxlix. 35,
1869 (Amer. Journ. Pharm. xxxviii. 568, xxxix. 122, xlii. 396).

8 Kepert. f. Pharm. xxxi. 37.

9 Annal. d. Chem. und Pharm. xlviii. 109, 1843 ; Iv. 105, 1845 (Pharm.
Journ. and Trans. [1], iii. 177 ; v. 228).

10 Vierteljahresschr. f. pract. Pharm. viii. 126, 1859.

11 Ibid. ix. 489, 1860 ; Annal. d. Chem. und Pharm. cxxi.372, 1862 (Amer.
Journ. Pharm. xxxii. 450, xxxiii. 122, xxxiv. 406).

12 Annal. d. Chem. und Pharm. (Suppl.) iv. 40. Miiller's alstonine from
Alstonia constricta is probably a mixture of these two alkaloids (Hesse).

13 Archiv d. Pharm. xlix. 153, 1847. Vierteljahresschr. f. pract. Pharm.
viii. 536, 1859 ; ix. 524, 1860. Annal. d. Chem. und Pharm. cxxxvii. 274,
1866. (See Bentley, Pharm. Journ. and Trans. [2], iv. 343, 1862 ; Amer.
Journ. Pharm. xxxiii. 112).

14 Chem. Centralblatt, 781, 1865 ; and N. Jahrb. f. Pharm. xxxi. 193, 1869
(Pharm. Journ. and Trans. [3], i. 682, 1871).

204 ALKALOIDS.

Ditamine (echitamine), see Gorup Besanez, and Hesse ;l for
ditaine see Harneck.2 The latter is glucosidal, like solanine, and
assumes a flesh-colour when treated with cone, sulphuric acid,
whereas ditamine turns splendid purple.

Geissospermine and aspidospermine, compare Fraude.3 The latter
yields a deep violet solution when warmed with excess of
perchloride of platinum ; heated with dilute sulphuric acid and a
little chlorate of potash, or with perchloric acid of sp. gr. 1*13, it
turns deep red ; with sulphuric acid and peroxide of lead, brown,
changing to cherry-red. If not quite pure, in the latter case a
violet colour is produced. At a temperature of 14° aspidosper-
mine dissolves in 6,000 parts of water, 48 of 98 per cent, spirit,
and 106 of ether.

Dukamarine, see Wittstein;4 alkaloid in Eschscholtzia, see Walz;5

1 Annal. d. Chem. und Pharm. clxxvi. 88, 326 ; clxxviii. 49, 1875 (Pharm.
Journ. and Trans. [3], vi. 142, 1875). Ber. d. d. chem. Ges. xiii. 1841, 1880
(Year-book Pharm. 171, 1881).

2 Archiv f. exper. Pathol. und Pharmacol. vii. 128, 1877. Ber. d. d. chem.
Ges. xi. 2004, 1878 (Yearbook Pharm. 188, 1878); ibid. xiii. 1645, 1880
(see also Pharm. Journ. and Trans. [3], viii. 803, 1878 ; xi. 331, 1870).
Scharlee's alstonine (Hesse's alstonanine) from Alstonia spectabilis appears to
be closely allied to ditamine, but crystallizes with facility.

3 Ber. d. d. chem. Ges. xi. 2189, 1878 (Year-book Pharm. 193, 1879) ; ibid,
xii. 1558, 1560 (Pharm. Journ. and Trans. [3], x. 712, 1880). See also my
observations in the Jahresb. f. Pharm. 120, 1878 ; and Hesse, ibid, 115,
1877 (Pharm. Journ. and Trans. [3], viii. 648, 1878). The name geissosper-
mine appears to have been applied to two different alkaloids, of which the one
discovered by Hesse yields reactions closely resembling those of aspidosper-
mine (red colouration with nitric acid, etc.). Hesse's geissospermine produces
a splendid red colour with sulphuric acid and bichromate of potassium, blue
with sulphuric acid and ferric salts, deep blue with Frohde's reagent, and
changes the colour of chloride of gold solution to a deep red. It can be
removed from solution by shaking with benzene or chloroform, and is accom-
panied by an alkaloid which is easily soluble in ether and turns reddish-
violet with sulphuric acid. The identity of aspidospermine and paytine
already alluded to (§ 186) is contested by Hesse. The same chemist has also
lately discovered a second alkaloid in quebracho, which he calls quebrachine ;
it is coloured blue with sulphuric acid and peroxide of lead (Ber. d. d. chem.
Ges. xiii. 2308 ; see Pharm. Journ. and Trans. [3], xii. 704). In examining
quebracho bark, I noticed that chloroform extracted from acid solutions (§ 55)
a small quantity of an alkaloid giving the reaction of aspidospermine. Solu-
tions rendered alkaline with ammonia yielded to petroleum spirit and benzene
a mixture that reacted like aspidospermine with sulphuric acid and chlorate of
potash, but was coloured splendid violet by Frbhde's reagent, and behaved like
strychnine to sulphuric acid and bichromate of potash. Compare also Arata,
Actas de la Acad. nac. in Buenos Aires, 1881 ; Hesse, Annal. d. Chem. u.
Pharm. ccxi. 249, 1882.

4 Pharm. Vierteljahresschr. i. 371, 495, 1850. Cf. § 167.

5 N. Jahrb. f. Pharm. viii. 223, 1857 (Amer. Journ. Pharm. xxxiv. 329).
Compare also my 'Ermittelung d. Gifte.'

§ 190. AMIDES; AMANITINE, ETC. 205

ylautine, see Probst;1 fumarine, see Pommier, Hannon, and
Preuss;2 gelsemine, see Eobbins3 (cf. §§ 55, 171); hydrastine,
see Perrins ;4 jurubebine, see Greene;5 loturine, see §168; meni-
spermine and paramenispermine, see Szteyner ; 6 oleandrine, see
Leukowsky;7 oxyacanthine, see Polex;8 pelletierine (punicine), see
Tanret.9

Pere'irine, see Goos.10 It dissolves with purple colour in nitric
acid.

Sparteine, see Mills (cf. § 55) ;n taxine, see Marme (cf. §§ 55,
171) ;12 lycopodine,13 nupharine.1*

§ 190. Amides. — The following are amides of less complex
constitution occasionally met with in plants :

Amanitine, which may be distinguished from muscarine by the
properties of the gold salt (§ 183) and by the negative results
of physiological experiments.15 It is isomeric, but not identical
with choline (neurine, sinkaline), and is converted into muscarine
by the action of nitric acid, whereas, under similar conditions,
choline yields beta'ine ( = butylalanine and oxyneurine). Musca-
rine differs from betaine in being more powerfully alkaline.16

1 Annal. d. Chem. und Pharm. xxix. 120, xxxi. 250, 1838 (Amer. Journ.
Pharm. xxxiii. 9).

2 N. Repert. f. Pharm. ii. 469, 1853 ; Vierteljahresschr. f. pract. Pharm.
iii. 68, 1852 ; Zeitschr. f. Chem. ii. 414, 1866.

3 Jahresb. f. Pharm. 152, 1876 (Amer. Journ. Pharm. 191, 1876). Robbing
identified the so-called gelsemic acid with aesculin.

4 Pharm. Journ. and Trans. [2], iii. 546, 1862. See also Mahla, Journ. f.
pract. Chem. xci. 248 ; Prescott, Amer. Journ. Pharm. xlvii. 481, 1875 ;
Hale, ibid. 247.

5 Amer. Journ. Pharm. xlix. 506, 1877.

6 Jahresb. f. Pharm. 141, 1878.

7 Ibid. xlvi. 397.

8 Archiv d. Pharm. [1], vi. 271, 1824 (Amer. Journ. Pharm. xxxiii. 455).

9 Journ. de Pharm. et de Chimie, xxviii. 168, 1878 (Pharm. Journ. and
Trans. [3], ix. 450).

10 Chem. Centralblatt, 610, 1839. Compare also Peretti, Journ. de Chim.
med. xxvi. 162.

11 Annal. d. Chem. und Pharm. cxxv. 71, 1862.

12 Jahresb. f. Pharm. 93, 1876 ; compare also 636, 1878 (Pharm. Journ. and
Trans. [3], 893, 1877).

13 Annal. d. Chem. und Pharm. ccviii. 363, 1881 (Pharm. Journ. and Trans.
[3], xii. 280, 1881).

14 Griming, loc. cit.

15 Compare Schmiedeberg, Ber. d.d.chem. Ges. iv. 693, 1871, and Harnack,
loc. cit. (Pharm. Journ. and Trans. [2], xi. 365, 1869).

16 For betaine see Scheibler, Ber. d. d. chem. Ges. ii. 292, 296, 1869 ; identity
with oxyneurine, ibid. iii. 155 ; with lycine see Husemann, Schweiz.

206 ALKALOIDS.

Choline and amanitine are also tolerably strongly alkaline. The
double salt of platinum and choline is precipitated by alcohol
from aqueous solution (contains 31-75 to 33-27 per cent. Pt.) ; the
gold double salt is sparingly soluble in cold water, more freely in
boiling (contains 44-25 to 44-9 per cent. Au.). The gold and
platinum double salts of betaine are freely soluble in water, and
especially so in alcohol, but more sparingly in ether.

§ 19.1. Asparagine. — This substance requires 40 parts of cold
and 4 of warm water for solution, and is insoluble in absolute
alcohol and in ether. It crystallizes in colourless rhombic prisms.
Boiling with hydrochloric acid resolves it into aspartic acid and
ammonia, a reaction upon which Sachsse1 based the following
method for the quantitative estimation: — 10 grams of the powdered
substance are boiled for a quarter of an hour with 200 cc. of a
mixture of equal volumes of alcohol and water, in a flask pro-
vided with an upright condenser \ 5 cc. of a cold saturated
alcoholic solution of mercuric chloride are diluted with 5 cc. of
water, and added to the mixture whilst still hot, the whole thrown
on a filter, and washed first with hot 50 per cent, spirit, and
finally with cold water. The filtrate and washings are evaporated
to dryness, the residue redissolved in the smallest possible quan-
tity of water (not more than 50 cc.), from which solution the
mercury is precipitated with sulphuretted hydrogen. The sulphide
of mercury is filtered off and washed with hot water until filtrate
and washings measure 110 to 120 cc. This liquid is then mixed
with 10 cc. of hydrochloric acid and boiled for an hour (with
upright condenser), by which the asparagine is decomposed into
ammonia and aspartic acid ; it is then cooled in an atmosphere
free from ammonia, and made slightly alkaline with pure potash.
The ammonia produced may be estimated gasometrically by
Knop's method; 14 parts by weight of nitrogen indicate 132 of
anhydrous asparagine. For asparagine, see also §§ 97, 210.

The microscopical detection of asparagine may be effected by
taking advantage of its insolubility in absolute alcohol. Crystal-
line deposits of that substance are usually formed when fresh
sections of plants containing it are placed in alcohol. After being
dried they are insoluble in a cold saturated aqueous solution of

Wochenschr. 1875 (Amer. Journ. Pharm. 209, 1875). Compare also Annal.
d. Chem. und Pharm. (Suppl.) ii. 383, iii. 245, 1864.

1 Journ. f. pract. Chem. vi. 118, 1873 (Journ. Chem. Soc. xxvi. 652).

§§191, 192. ASPARAGINE; GLUTAMINE; LEUCINE. 207

asparagine, and melt at 100° to a homogeneous mass easily soluble
in water. Should the addition of alcohol not be followed by the
immediate formation of crystals, Borodin recommends covering
the object with a coverslip, allowing the spirit to evaporate, and
then again looking for crystals.

Schulze and Ulrich detected glutamine in beet-juice by precipi-
tating with a slight excess of basic acetate of lead and filtering.
To the filtrate which contains the glutamine, hydrochloric acid is
added in the proportion of 25 cc. to a litre ; on boiling for two
hours the glutamine is decomposed, like asparagine, into ammonia
and the corresponding acid (glutamic acid). The greater part of
the hydrochloric acid is now removed by concentrated solution
of acetate of lead, and to the filtrate basic acetate of lead is
added until the precipitate first formed is redissolved, with the
exception of the remainder of the chloride of lead. The lead
salt of glutamic acid is then precipitated from the filtered solu-
tion by the addition of alcohol. It is collected, decomposed
with sulphuretted hydrogen, and filtered from the sulphide of
lead. After expelling the excess of sulphuretted hydrogen
from the liquid, oxide of silver is added to remove any hydro-
chloric acid present, the solution freed from silver by sulphuretted
hydrogen, and evaporated to crystallization. The glutamic acid
thus obtained may be purified by conversion into a copper salt
and regeneration by sulphuretted hydrogen. The presence of
glutamic acid was confirmed by converting with nitrous acid into
the corresponding oxy-acid, from which pyrotartaric acid was
obtained by the action of hydriodic acid.

The last portion of glutamic acid from the crystallization of
the crude product was found to contain aspartic acid.1

Glutamine may be estimated quantitatively in the same manner
as asparagine.

For the quantitative determination of asparagine, leucine, tyrosine,
etc., see also § 241.

§ 192. Leucine. — This substance has also been detected in
certain plants.2 It may be separated from albuminous substances
by dialysis, and if present in solution with asparagine, will be
found in the mother-liquor after the crystallization of the latter.

1 Compare Zeitschr. f. anal. Chem. xvii. 104, 1878.

2 Compare, for instance, Gorup Besanez, Ber. d. d. chem. Ges. vii. 146,
569, 1874 (Journ. Chem. Soc. xxvii. 494).

208 VEGETABLE MUCILAGE.

It is characterized by crystallizing in sphsero-crystals, by its be-
haviour to water and alcohol (dissolves in 27 parts of cold, and
easily in warm water, in 1040 of cold 96 per cent, spirit, and
800 of boiling 98 per cent.), by its power of dissolving oxide of
copper, and by yielding leucic acid when acted upon by nitrous
acid.

I have already directed attention to the identity of the cheno-
podine obtained from decomposing yeast with leucine.1 Gorup
Besanez has made the same assertions of the chenopodine from
Chenopodium album.

Tyrosine, as well as leucine, has lately been detected in plants,
especially in germinating seeds.2 Aqueous extracts of the material
under examination are concentrated, precipitated with alcohol,
filtered, freed from alcohol by distillation, evaporated to a syrup,
and allowed to stand, when the tyrosine separates out in groups
of warty crystals. By recrystallization from ammoniacal alcohol
it may be obtained in acicular crystals. Solutions of the latter
develop a rose-colour with mercuric nitrate and a little nitrous
acid. Warmed to 50° with concentrated sulphuric acid (half-hour),
and saturated with carbonate of barium, it yields a mass which
assumes a fine violet with ferric chloride.

Ratanhin agrees with tyrosine in most of its reactions, especially
the two just described. It is almost insoluble in cold water,
alcohol and ether, sparingly soluble in boiling water, but freely in
ammonia. Suspended in water, and then warmed with a little
nitric acid, it dissolves, passing, as it does so, from rose to ruby-
red and blue, turning finally green with red fluorescence. 3

VEGETABLE MUCILAGE.

§ 193. Vegetable Mucilage, Pectin, etc. — The substances desig-
nated by these names are a source of much inconvenience to the
analyst, due probably to their occurring in various modifications

1 Compare Bergman, ' Das putride Gift,' Dorpat Glaser. See also Reinsch,
N. Jahrb. f. Pharm. xxvii. 123, 1867.

2 Compare Schulze and Barbieri, Ber. d. d. chem. Ges. x. 199, xi. 710
(Journ. Chem. Soc. xxxiv. 663).

3 It is notorious that ratanhin does not occur in rhatany-root, and that its
presence in certain samples of commercial extract of rhatany is due to adultera-
tion. Compare also Kreitmair, Jahresb. f. Pharm. 136, 1874 (Year-book
Pharm. 90, 1875). Gintl believes ratanhin to be identical with angelin from
Ferreira spectabilis (Zeitschr. d. osterr. Apoth. Ver. 32, 1869).

§§ 193, 194. EXTRACTION. 209

differing greatly from one another in solubility, etc. The majority
of them are characterized by a certain disposition to combine with
lime, potash, etc., and this has led to their classification with the
weak organic acids (arabic acid, etc.) ; in fact, some of the differ-
ences in solubility, etc., seem occasionally to depend directly
upon the quantity and quality of the bases with which they are
combined.1

But other substances, such as albumen, tannin, etc., that simply
accompany the pectin and mucilage, can also exercise an influence
on the behaviour of the latter to solvents. On this account, and
because, as a rule, such matters as mucilage diffuse but slowly, it
is not always possible, in extracting vegetable substances with
water according to § 71, to be certain that all the mucilage (arabin,
etc.) soluble in water has really passed into solution. If heat were
employed, the amount dissolved would certainly be increased, but
at the same time other and more serious errors would be intro-
duced.

One such source of error is to be found in the presence of
carbohydrates closely allied to soluble mucilage, but differing
from it in only swelling (not dissolving) in cold water (metarabic
acid, etc.). These carbohydrates are of frequent occurrence in
plants. Prolonged heating with water gradually dissolves them.
Error would also be caused by carbohydrates like lichenin,
caraghin, starch, etc., hot solutions of which gelatinize on cooling,
as well as by other substances.

§ 194. Modified Method of Examination for Mucilage, etc. — For the
reasons given in § 193, I think it is preferable to extract with
cold water, and estimate the mucilage and albumen in the solution
prepared according to § 71. The washings mentioned in that
section should be evaporated to a syrup, in which , a similar deter-
mination of mucilage and albumen should be made. If the
material has been macerated with exactly 100 cc. of water, and
65 cc. of filtrate have been obtained (used for the first determina-
tion of albumen, etc.), then 35 cc. must be retained by the residue
and filter, and these 35 cc. must be extracted by the washing. If the

1 This was clearly the case in peony-seed (Archiv d. Pharm. [3], xiv. 426,
1879 ; Journ. Chem. Soc. xxxv. 1043). Treatment of the seed with alcoholic
tartaric acid rendered far more arabic acid soluble in water than it was
possible to extract by direct treatment with the latter menstruum. It had
evidently been liberated from combination by tartaric acid, and rendered
soluble in water.

14

210 VEGETABLE MUCILAGE.

extraction has been complete, the amount of albumen, etc., in the
washings must be the same as that in 35 cc. of the first filtrate
(which may be calculated from the first estimation) ; but should
the washings contain more than the corresponding quantity of
filtrate, the excess must be added to the total of the analysis.

§ 195. Characters of Soluble Mucilage. — Apart from their being
dissolved by water and precipitated by alcohol from aqueous
solution, vegetable gum, arabin, arabic or gummic acid, is also
characterized by being converted into glucose when boiled with a
dilute acid. It must, however, be observed, that the various
arabic acids, according to their origin, yield glucoses differing to a
certain .extent from one another, some being more powerfully
dextro-, others laevo-rotatory ; some crystallizing with facility,
others again not at all, or only with difficulty, or passing first
through an intermediate stage as dextrin (according to Kirchner
with simultaneous production of cellulose). By means of these
properties, vegetable mucilages of particular origin can sometimes
be accurately described. Some years ago it was shown by
Scheibler1 that the arabic acid of beet-root yielded, on inversion,
a considerable quantity of dextro-rotatory arabinose, which
crystallizes with such facility that it was at first thought to be
mannite.

Kiliani has recently asserted the identity of arabinose with
lactose. Many varieties of gum arabic also behave like arabic
acid, whilst some which are not otherwise distinguishable from
good gum, differ in yielding lasvo-rotatory non-crystallizable
glucose. In addition to these, B6champ2 has recently discovered
a ' gummicose ' which appears to be allied to galactose (§ 205). I
am almost inclined to think that a minute investigation of these
properties might enable us to distinguish between the various
forms of vegetable mucilage soluble in water.3

The examination of the oxidation-products obtained by the

1 Ber. d. d. chem. Ges. vi. 612, 1873 ; Journ. f. pract. Chem. ciii. 458,
1868 (Journ. Chem. Soc. xxvi. 1124). See also Neubauer, Jahresb. f . Pharm.
6, 1854, and Grseger, ibid. 218, 1872.

2 Compare Bechamp, Journ. de Pharm. et de Chim. xxvii. 51, 1878.

3 In general it may be said that the action of dilute acids must be continued
for a longer time to convert vegetable mucilage (arabin) into glucose than is
necessary for dextrin, triticin, etc. But it must be left for further experi-
ments to show to what extent the amount of glucose produced may be taken
as an indication of the quantity of arabin originally present.

§ 195. ARABIC ACID. 211

action of nitric acid may also result in the discovery of distinctive
properties. Special attention should be directed to the presence
among these oxidation-products of mucic acid, and to the quantity
in which it is yielded.

The action of aqueous solutions of these mucilaginous sub-
stances on polarized light also requires further investigation. It is
at all events certain that some arabins are powerfully laevo-
rotatory (cf. § 146), others feebly so, whilst some again are dextro-
rotatory.

By the action of hydrochloric, or tolerably dilute sulphuric
acid, or spirit containing 10 per cent, of the latter, arabic acid is
converted into metarabic acid (§ 226) which is characterized by only
swelling in water. This modification can be converted into arabic
acid by boiling with a very dilute non-oxidizing acid, a little sugar
being simultaneously produced. A similar change to arabic acid
takes place when metarabic acid is triturated with sufficient lime
or baryta water to dissolve it, a lime or baryta salt of arabic acid
being formed.

Arabic acid agrees in its essential properties with metapectic
acid, and approaches pectic acid in such a manner as to allow of
the conjecture that the latter, when examined in a state of purity,
will prove identical with it ; in fact, I am of the same opinion as
Eeichardt1 and others — viz., that the so-called pectin substances
are nothing else than the various forms of vegetable mucilage and
its nearest allies.

The insolubility of these mucilaginous and c pectinous ' sub-
stances in alcohol and ether, and the property they possess of
swelling in contact with water, allow of their detection micro-
scopically. They are generally coloured yellow by iodine water
(for allied substances coloured blue with iodine, see § 244).
Aniline violet colours vegetable mucilage red.

§196. Varieties of Gum Arabic. — Masing2has published com-
munications on the behaviour to reagents (§ 73) of arabic acid,
and different varieties of gum arabic, and its more important
surrogates. It appears that 10 per cent, aqueous solutions of
these substances are not precipitated by cold saturated solution of
acetate of copper, 10 per cent, acetate of lead solution, or by ferric

1 Archiv d. Pharm. [3], x. 116, 1877 (Journ. Chem. Soc. xxxii. 502).

2 Archiv d. Pharm. [3], xv. 216, 1879 ; xvii. 34, 1880 (Year-book Pharm.
191, 1881 ; Journ. Chem. Soc. xl. 212).

14—2

212 DEXTRIN, TRITICIN, ETC.

chloride of sp. gr. 1 *2 ; a cloudiness or precipitate produced in
some samples (e.g. Feronia elephantum) is probably due to con-
tamination. Silicate of potash (1 part of thick soluble glass
diluted with 20 parts of water) produces in solutions of gum
arabic, and most of its surrogates, a cloudiness or precipitate
which partially or wholly redissolves on adding excess. Arabic
acid remains clear, or becomes only slightly turbid. The same
reagent does not precipitate the partially soluble gum from
species of Cactus, Cedrela, or Ehizophora, or solutions of the gum
from Acacia catechu, A. leucophloea, and species of Albizza,
Azedirachta, Odina and Conocarpus. A 2 per cent, solution of
stannate of potash yields reactions resembling in general those of
silicate of potash, but produces in solutions of arabic acid a pre-
cipitate that redissolves in excess. A 10 per cent, solution of
neutral sulphate of aluminium gives, as a rule, a precipitate, and
this is in many cases soluble in caustic potash of sp. gr. 1-13.
Basic acetate of lead also produces a precipitate, which is generally
partially or wholly soluble in excess.

§ 197. Separation from Dextrin, etc. — The behaviour of the muci-
laginous substances soluble in water to basic acetate of lead
furnishes us with the means of getting rid of them, should we
wish to make optical or chemical experiments with extracts of
vegetable substances for the detection of glucose, saccharose, dextrin,
triticin, etc. (cf. §§ 76, 83) ; care must be taken, however, not to
add any large excess of the precipitant. If this precaution is
observed, such substances as arabin and dextrin can, I think, be
more completely separated than by the precipitation with alcohol,
recommended in §§ 75, 76. In the latter, ethylic alcohol can, as
I showed some years since, be replaced by methylic.1

DEXTRIN, TRITICIN, SINISTRIN, LEVULIN.

§ 198. Characters. — These carbohydrates are all easily converted
into glucoses (§ 76) by dilute acids. Dextrin may be distinguished
by its yielding grape-sugar, whilst triticin, sinistrin and levulin
are converted into levulose, and are also characterized by their
behaviour to baryta-water (see also § 77). Levulin 2 is optically

1 Phann. Zeitschr. f. Eussland, iv. 152, 1866 (note).

2 Compare Weyher v. Reidemeister, 'Beitr. z. Kenntniss d. Levulins, etc.'
Diss. Dorpat, 1880.

§§ 198, 199. COMPOSITION AND ESTIMATION. 213

inactive; sinistrin and triticin1 differ from one another in the
extent to which they deviate a ray of polarized light. Triticin
reduces Fehling's solution rapidly, but levulin and sinistrin require
long boiling before cuprous oxide separates out (levulin, 1 ^ hour).
These three carbohydrates also differ in the rapidity with which
they are converted into glucose when heated with pure water in
sealed tubes. Triticin is here the first to undergo a partial trans-
formation into sugar. Levulin is more easily converted by yeast
into carbonic acid and alcohol than is either triticin or sinistrin.

§ 199. Alcoholates of the foregoing Carbohydrates, Composition,
Quantitative Estimation, etc. — The precipitates of levulin, triticin
and sinistrin produced by spirit retain notable quantities of
alcohol in such a manner as to necessitate the inference that
distinct akoholates have been formed. Even after standing for
three months over sulphuric acid the levulin compound had not
lost all its alcohol, whilst in a partial vacuum it had disappeared
in the course of two months. Prolonged heating to 110,° a
temperature at which the alcoholate melts, is sufficient to cause
the gradual expulsion of the alcohol.

In estimating the four carbohydrates in question by calculation
from the amount of sugar yielded by the action of dilute acids, it
must be remembered that the composition of dextrin, sinistrin
and levulin, dried at 100°, has been found by analysis to corres-
pond to the formula C6H1005, but that triticin dried at 110°
has the same composition as cane-sugar : viz., C12H22011.

In these cases the glucose (§ 76) is better estimated by Fehling's
solution (§ 83) than by polarization (§ 208). Solutions of levulin,
triticin and sinistrin, although inverted with dilute acids only, do
not always show an angle of rotation = 106° to 107° (§ 205), even
if the solution be neutralized, evaporated to dryness, redissolved
in cold water, and tested immediately. On cooling the solution
after inversion and examining at once, levulin yielded, in the
most favourable instances, a sugar with a rotatory power of 81°,
triticin, 94°, and sinistrin, 96° ; and it was only by conducting
the inversion in sealed tubes that Eeidemeister obtained for
triticin-sugar a rotation of 106-5°, indicating the presence of
pure levulose.2

1 For mycodextrin and mycinulin see Ludwig and Busse, Archiv d. Pharm.
clxxxix. 24, 1869.

2 Compare Reidemeister, loc. cit.

214 GLUCOSES, SACCHAROSES, ETC.

For the complete inversion of 1 to 1 -3 grams of carbohydrate
dissolved in 35 cc. of water, 5 to 6 drops of hydrochloric acid
(33 per cent.) were found sufficient; in the case of levulin, two to
two and a half hours' boiling is required, whilst triticin is com-
pletely converted in twenty-five to thirty minutes (Reidemeister).

To obtain accurate results the acid must be as dilute as possible,
and the action stopped as soon as the inversion is complete. Here,
as in many other instances, hydrochloric acid seems to be prefer-
able to sulphuric ; considerable quantities of sugar (20 to 30 per
cent.) may otherwise be lost by secondary decompositions, and in
consequence the estimation of the carbohydrate be attended with
results inaccurate in the extreme.

For the estimation of glucose by titration, see §§ 83, 84.

For dextrin, see also §§ 200, 201, 202.

GLUCOSES, SACCHAROSES, ETC.

§ 200. Detection of Grape-sugar. — To detect grape-sugar (§§ 70,
83 to 88), Mulder 1 makes use of its reducing action on indigo.
The solution to be examined is rendered faintly blue with sulphin-
digotic acid ; carbonate of soda is then added until the reaction is
alkaline, and the whole boiled for a few seconds. If grape-sugar
is present, the colour passes from blue to violet, and then dis-
appears ; the liquid should not, however, be shaken, as the action
of the air results in the rapid return of the blue colour.2

Tincture of litmus, substituted by Vogel3 for indigo, is less
sensitive.

Braun 4 directs attention to the reaction between glucose and
picric acid, and recommends this reagent for distinguishing
between grape- and cane-sugar. In the presence of caustic soda
picric acid is converted by boiling with grape-sugar into blood-red
picramic acid. Fruit- and milk-sugar exert a similar action, which
is not shared by mannite or cane-sugar.

For the action of grape-sugar on ferridcyanide of potassium,
see Gentele 5 and Lenssen.6 The latter also discusses the reduc-

1 Chem. Centralblatt, 176, 1861 (Pharm. Journ. and Trans. [1], xviii. 421).

2 Compare Neubauer, Zeitschr. f. anal. Chem. i. 378, 1862.

3 N. Kepert. f. Pharm. xi. 62, 1862.

4 Zeitschr. f. anal. Chem. iv. 185, 1865.

5 Chem. Centralblatt, 91, 1861 ; Stahlschmidt, Ber. d. d. chem. Ges. 141,
1861 (Amer. Journ. Pharm. xxxii. 81).

6 Zeitschr. f. anal. Chem. ix. 453, 1870.

§§ 201, 202. ESTIMATION. 215

tion of cyanide of mercury by glucose as recommended by Knapp1
(§ 84), and shows that by neither method can saccharose be accur-
ately distinguished from glucose.

O. Schmidt distinguishes between grape- and cane-sugar by
adding basic acetate of lead and ammonia, and warming. The
white precipitate that first appears turns red if grape-sugar is
present; cane-sugar does not yield this reaction.2

§ 201. Estimation of Glucose in Presence of Saccharose. — In titrating
glucose in the presence of saccharose, it is advisable, according to
Eumpf and Heinzerling,3 to conduct the experiment with the
utmost rapidity, as the error caused by the dextrin is then but
very small.

Barfoed detects grape-sugar in the presence of dextrin by means of
an aqueous solution of crystallized acetate of copper (1 in 15),
containing 1 per cent, of acetic acid. To the liquid under
examination a few drops of the reagent are added, the whole
boiled for an instant and cooled. If grape-sugar is present,
cuprous oxide gradually separates out.* Cane-sugar, milk-sugar,
and gum behave like dextrin. These statements have been
confirmed by Miiller.5

§ 202. Detection of Dextrin in Presence of Cane-sugar. — Scheibler6
has shown that a 20 per cent, aqueous solution becomes cloudy
on the addition of 4 volumes of 90 to 95 per cent, alcohol if the
sugar is contaminated with as little as even -5 per cent, of dextrin.
A second test of Scheibler's, depending upon the use of iodine,
may be passed over here, as it succeeds with impure dextrin only.
The presence of dextrin and cane-sugar in solution together may
often be inferred if, after inversion, Fehling's solution shows less
grape-sugar than could have been anticipated by calculation from
the rotatory power before inversion ; or if the rotatory power
after inversion is less than that before inversion (taken as due to
pure cane-sugar) would have led us to expect. (See § 207.)

§ 203. Gravimetric Estimation of Glucose. — Mulder recommends

1 Annal. d. Chem. und Pharm. cliv. 252 (Pharm. Journ. and Trans. [3], i.
301, 1870).

2 Annal. d. Chem. und Pharm. cxix. 102, 1861.

3 Zeitschr. f. anal. Chem. ix. 358, 1870. Compare also Barfoed, ibid. xii.
29, 1873 (Year-book Pharm. 176, 1874).

4 Zeitschr. f. anal. Chem. xii. 27, 1873 (Journ. Chem. Soc. xxvi. 1163).

5 Zeitschr. f. anal. Chem. xviii. 601 (Year-book Pharm. 74, 76, 1879).

6 Zeitschr. f. anal. Chem. x. 372, 1871.

216 GLUCOSES, SACCHAROSES, ETC.

for this purpose heating for an hour to 60° with excess of alkaline
copper solution, filtering off, and weighing the cuprous oxide pre-
cipitated (§ 83). The errors involved by this method, which at
the best of times can yield only approximate results, have been
the subject of communications by Fresenius1 and Gratama.2

§ 204. Fermentation Test (§ 85). — To detect glucose by this test
a little of the suspected solution is evaporated until it contains at
least 5 per cent, of sugar. After cooling a few drops of tartaric
acid solution are added, and a little good yeast, previously washed
with distilled water ; 1-2 cc. of this mixture are then introduced
into a eudiometer standing over mercury. If glucose is present

Fig. 9.

an evolution of carbonic acid will soon begin, and should, in a few
hours, displace a considerable amount of mercury (§ 61). By
means of a blank experiment with distilled water, and the same
quantity of yeast, it may be ascertained whether any carbonic acid
has been produced by the yeast itself alone.

The absence of any evolution of carbonic acid is not necessarily
a proof that the liquid is free from glucose. Certain constituents
of plants, such as salicylic acid, thymol, etc., may occasionally be
present, and prevent any fermentation taking place. 3

1 Anleit. zur quant. Analyse, 5th edition, 833.

2 Zeitschr. f. anal. Chem. xvii. 1875, 1878 (Journ. Chem. Soc. xxxiv. 611).

3 Compare Werncke, 'Ueber die Wirkung einiger Antiseptica auf Hefe.'
Diss. Dorpat, 1879.

§ 205. CHARACTERS OF GLUCOSES. 217

If this is the case, such a method cannot of course be employed
for the quantitative determination of the glucose. But if the solution
soon passes into a state of fermentation, and a tolerably large
quantity of gas is produced, an estimation of the amount of
glucose present may be made in the following manner: The
glucose solution is prepared as directed for the qualitative test,
and a measured quantity of it introduced into the flask A (Fig. 9).
The second flask B, shown in the figure, contains sulphuric acid,
as for the determination of carbonic acid according to the method
of Fresenius and Will. The whole apparatus is wiped dry, ac-
curately weighed, and exposed to a temperature of 20° to 30°.
The carbonic acid evolved in A, passes through c, and is dried by
the sulphuric acid in B, before being expelled through d. After
the lapse of about two days, when the evolution of gas has ceased,
the carbonic acid in the apparatus is driven out by aspirating at d.
The difference in weight is the amount of carbonic acid produced,
100 parts of which are equivalent to 204*54 of glucose.1

§ 205. Characters of the Various Glucoses.— In speaking of glucoses
in the preceding paragraphs, I referred principally to grape-sugar,
fruit-sugar, and the combination of both known as invert-sugar.
Grape-sugar .(dextrose) possesses the following characters : it can
be obtained, by gradual deposition from solution, in prismatic
crystals2 containing one molecule of water (cf. § 89) ; an aqueous
solution, prepared fresh and without heat, in which the sugar is
present in the crystalline modification, shows a rotatory power for
(a)D + 91'81° (p = 1) ; whereas a solution that has been heated, in
which the sugar has passed into the amorphous condition, possesses
for (a)D a rotatory power of 49'54° to 50'00°, and 46'34°3(p = 12).
Hoppe Seyler4 found the rotatory power of amorphous grape-
sugar to be (a)D = 56-4°, from which he obtained the constant
quantity A'D = 1773'0; this may be used for calculating the

1 Another method that has been suggested of estimating glucose consists
in determining the specific gravity before and after fermentation (for 20 to 24
hours) and calculating 0'219 per cent, of glucose for each O'OOl in the differ-
ence. Manasse'in has shown that the method yields good results with the
sugar in urine (Med. Centralblatt, 551, 1872).

2 Similar crystalline deposits, especially sphserocrystals, have been occa-
sionally observed in the microscopic examination of dried drugs. Compare
Braun, Zeitschr. d. oesterr. Apoth. Ver. xvi. 337, 1878.

3 Compare Hesse, Annal. d. Chem. und Pharm. clxxvi, 89, 1875 (Pharm.
Journ. and Trans. [3], vii. 191 et seq.).

4 Zeitschr. f. anal. Chem. xiv. 303, 1875.

218 GLUCOSES, SACCHAROSES, ETC.

amount of grape-sugar present from the rotation observed. For
anhydrous dextrose Tollens and v. Grote1 ascertained (a)D = 53 '10°,
and the constant quantity = 1883-3. Hesse has shown that the
prolonged heating of aqueous solutions of dextrose reduces the
angle of rotation still further.

Biot has asserted the existence of glucoses, agreeing with grape-
sugar in all important properties, but differing from it in their
rotatory power ; and the truth of this assertion has been proved
by Hesse. An instance may be cited in salicin-sugar, the crystalline
modification of which possesses a rotatory power («)D = 100° (p = 1),
and the amorphous («)D = 50° (populin-sugar is said to correspond
to ordinary dextrose); the rotatory power of phlorose from phloricin
is five-sixths that of glucose. 2

Fruit-sugar (levulose) has recently been obtained in acicular
crystals ;3 a freshly prepared solution shows a rotatory power
(a)D=-106° (constant 943'4; see also note to §209), which
slowly diminishes, on boiling, to — 56°. Levulose dissolves more
easily in alcohol than crystalline dextrose, which may therefore, to
a certain extent, be freed from the former by washing with spirit.
The disposition to form a sparingly soluble compound with lime
is very characteristic of levulose, and forms, at the same time, a
means of separating this from grape and other sugars. Like
dextrose, levulose is fermentable; but when both sugars are
present together, the former is the first to undergo alcoholic
fermentation.

Sugars allied to levulose, differing from it only in the rotatory
power, will probably be found in certain plants (Jerusalem arti-
chokes, etc. ; see also § 199).

Invert-sugar (see also § 209 et seq.) shows as a rule a rotatory
power for (a)D of - 18°. The majority of chemists regard it as a
mixture of grape- and fruit-sugar, molecule for molecule ; but
Maume"n64 differs from them, and maintains that he has found in
it, in addition to these two constituents, another, optically in-
active, unstable sugar.

1 Ber. d. d. chem. Ges. 487, 616, 1531, 1876. See also Hesse, Annal. d.
Chem. und Pharm. cxcii. 169, 1879.

2 Compare Hesse, Annal. d. Chem. und Pharm. cxcii. 173, 1878.

3 Jungfleisch and Lefranc, Comptes rendus, xciii. 547.

4 Journ. d. Pharm. et de Chim. xxii. 47, 1875. The name of chylariose has
been given by Maumene to the leevo-rotatory constituent of invert-sugar.

§ 206. SO£BIN, INOSITE, ETC. 219

According to the researches of Scheibler,1 a freshly prepared
solution of araUnose possesses a rotatory power (a)D=+121°,
diminishing, after heating, to +116°. It crystallizes, far more
easily than dextrose, in rhombic crystals ; but is not directly fer-
mentable. Its action on Fehling's solution resembles that of
grape-sugar. As already observed Kiliani maintains that arabinose,
when treated with nitric acid, yields mucic acid, and is identical
with lactose. (This is contradicted by Clsesson.)

For caragheen-sugar see Bente.2 It is said to be optically
inactive, and to reduce Fehling.

Galactose, regarded by Fudakowski3 as a mixture of lactose and
another glucose, also belongs to this group. It differs from most
other glucoses in yielding mucic instead of oxalic acid when treated
with nitric acid. (See also § 195,)

§ 206. Sorbin, Inosite, etc. — Sorbin, inosite, and eucalyn differ
considerably in their properties from the foregoing sugars, but
correspond to the glucoses in formula.

SorUn can be obtained in colourless crystals, which are freely
soluble in water, sparingly in cold spirit. It reduces Fehling,
possesses a rotatory power («)/= —46 '9°; but is not ferment-
able. Sorbin must not be confounded with the sorbite belonging
to the mannite group (§212).

Inosite, or phaseomannite, forms colourless rhombic plates melting
at 210°, soluble at 19° in 6 parts of water, insoluble in cold absolute
alcohol and ether. It is not fermentable, does not reduce Fehling,
and is optically inactive. 4 When warmed with nitric acid and
dried, inosite is said to leave a residue that is coloured purple or
blue by ammonia and chloride of calcium.

Eucalyn has been obtained, up to the present time, only in the
form of an uncrystallizable, non-fermentable syrup. It possesses
for (a)r a dextro-rotatory power of 65°.5

1 Ber. d. d. chem. Ges. vi. 612, 1873.

2 Ibid. ix. 1157, 1876.

3 Ibid. viii. 599, 1875 ; ix. 42, 1876.

4 On the occurrence of inosite in the vegetable kingdon (grape- juice) see
Hilger, Annal. d. Chem. und Pharm. clx. 333, 1871 (Year-book Pharm. 156,
1872) ; also Neugebauer, Zeitschr. f. anal. Chem. xii. 39, 1873. Neugebauer
has found inosite in vine-leaves also, and at the same time discusses the detec-
tion of quercetin, quercitrin, etc. NucUe, which has been discovered in hazel-
leaves, appears to be very similar to inosite (Jahresb. f. Pharm. 167, 1877).

5 For some other saccharine bodies that have been hitherto but little
investigated, such as dambose, etc., see Ber. d. d. chem. Ges. vi. 1314, 1873.

220 GLUCOSES, SACCHAROSES, ETC.

§ 207. Saccharoses. — Cane-sugar differs from the glucoses in
composition ; its formula, C12H22On, is the same as that of certain
carbohydrates of the vegetable gum group, triticin, etc. It crystal-
lizes with tolerable facility in anhydrous monoclinic crystals, is
freely soluble in cold water, insoluble in ether, and in cold absolute
alcohol ; the latter, when heated to boiling, dissolves about 1 '25
per cent. An aqueous solution is dextro-rotatory. Hesse l found
the rotatory power for («)D to be + 67'950(p = l) and +66-50°
(j? = 10);2Tollens,3 +66'649°,and + 66'475°(p = 10);andSchmitz,
+ 6 6 -52 7°. Heated for some time to about 160°, cane-sugar is con-
verted into dextrose and levulosan (C6H1005) ; at a higher tempera-
ture it is decomposed into caramel and other products. It does
not reduce alkaline copper solution in the cold ; prolonged boil-
ing, however, causes the gradual separation of cuprous oxide.
Cane-sugar is only indirectly fermentable, being first gradually
converted into glucose by the invertin of the yeast (§ 230). It
has already been observed (§§ 86, 88, etc.) that a similar change
is easily brought about by the action of dilute acids ; the principal
means of distinguishing cane-sugar from the more important
glucoses have also been mentioned (see §§ 200 to 204 and § 206).

The following saccharoses are isomeric with cane-sugar and
classed with it.

Milk-sugar, which has not yet been detected with certainty in
the vegetable kingdom, forms rhombic crystals containing 1
molecule of water of crystallization and soluble in 7 parts of water
at 10°. Its rotatory power (in solutions that have been previously
heated) is (o)D= + 53'63° (p = 2); Hesse found for freshly pre-
pared cold solutions (a)D = +80 -68°. It is not directly ferment-
able, but, like cane-sugar, is gradually inverted by yeast. The
action of dilute acids results in the production of galactose
(J 205) ; by oxidation with nitric acid it yields large quantities
of mucic acid. Milk-sugar reduces ammoniacal silver and alkaline
copper solution in the cold, but the extent to which reduction is
effected when boiled with the latter reagent is less than is the case
with dextrose. When converted into galactose the reducing power

1 Loc. tit. Calderon found (a)D = 67'09° (Journ. de Pharm. et de. Chim.
xxiv. 437, 1876).

2 For the decrease in rotatory power caused by the presence of certain salts
see Muntz, Ber. d. d. chem. Ges. ix. 962, 1876.

3 Ber. d. d. chem. Ges. x. 1403, 1877 ; xi. 1800, 1878. See also Schmitz,
ibid. x. 1414.

§ 208. ESTIMATION BY POLARIZATION. 221

is about the same as that of invert-sugar, so that after inversion
10 cc. of Fehling indicate about 0*0475 gram milk-sugar.1

To Maltose, produced together with dextrin by the action of
diastase on starch, Schulze2 assigns the fornmla C12H22011 + Hi,0.
It resembles milk-sugar in its behaviour to alkaline copper solution.
Boiling with dilute acids converts it entirely into dextrose, and, as
with milk-sugar, it is advisable to invert maltose before estimating
it with Fehling's solution. Its rotatory power is greater than
than that of dextrose ; (a)D = 149-5 - 150-6°. Maltose is said to be
(? directly) fermentable. With nitric acid it yields no mucic acid.

Melitose crystallizes in needles containing 3 molecules of water.
It is soluble in 9 parts of cold water, and is dextro-rotatory
( + 102°). Boiling with dilute acids converts it into glucose and
eucalyn, the latter of which is not fermentable. Yeast also acts
in a similar manner (§ 206), in which case the glucose produced
ferments. With nitric acid melitose yields abundance of mucic acid.

Melezitose crystallizes in rhombic prisms with 1 molecule of
water of crystallization. It is freely soluble in water, insoluble
in alcohol and in ether. An aqueous solution is dextro-rotatory
(94-48°), and indifferent to Fehling's solution ; it is converted into
glucose when boiled with a dilute acid ; yields with nitric acid
no mucic acid, and is slowly decomposed by yeast.

Mycose (trehalose) forms rhombic prisms containing 2 molecules
of water. Boiling spirit dissolves it tolerably freely ; in aqueous
solution it is .powerfully dextro-rotatory ( + 220°), only slowly
and incompletely fermented by yeast, and converted into dextrose
when boiled with dilute acid for several hours. It does not
reduce copper solution, and yields no mucic acid with nitric acid.

§ 208. Estimation by Polarization. — This is possible when the
glucose or saccharose is not accompanied by a^ny other similar
carbohydrate, and when the solution contains no other substance
(asparagine, etc.) that has an action on polarized light, or when
all such substances present can be completely removed, either by
boiling (as albumen), or by precipitation with basic acetate of
lead (organic acids, gum, etc.) (§ 210). Of course the rotation-

1 Compare Kodewald and Tollens, Ber. d. d. chem. Ges. xi. 2076, 1878
(Year-book Pharm. 77, 1879).

2 Ber. d. d. chem. Ges. vii. 1047, 1874 (Year-book Pharm. 85, 1875), and
Journ. f. Landwirthschaft, xxvi. 67, 1878. See also O'Sullivan, Muniteur scient.
March, 1874 ; and Ber. d. d. chem. Ges. ix. 281, 1876 (Journ. Chem. Soc.).

222 GLUCOSES, SACCHAROSES, ETC.

constant of the carbohydrate in question must be known. The
results are generally calculated from the equation

where C is the weight of the substance (expressed in grams) con-
tained in a litre of solution, A the rotation-constant of the
substance to be estimated, a the observed rotation, and L the
length of the column of solution in millimetres. If the concen-
tration of the solution has an influence on the optical activity,
then j?, the weight of substance in grams in 100 cc. of the solution,
must also be taken into account.1 The same must be done for
the temperature when that exerts any influence on the rotatory
power (invert-sugar) (cf. § 199).

Suppose for instance a solution of grape-sugar in a tube 0*1
metre long to have shown a rotatory power +3°, then (using
Tollens and Grote's constant),

C = 1883-2 XT^

For a solution of levulose with rotatory power — 3°,
C = 943-4

For a solution of cane-sugar with rotatory power +3° (using
Wild's constant),

C = 1505-6

In the first instance the solution would contain 56*496 grams
of dextrose per litre; in the second, 28*302 grams of levulose in
the third, 45*168 grams of cane-sugar. See also § 210.

§ 209. Estimation of two Sugars. — Two sugars present in solution
together may be accurately estimated, provided that the rotatory
power of each is known, and the other conditions in § 208 are
fulfilled. This is frequently the case with solutions of dextrose
and levulose. Neubauer2 then recommends observing the rotatory
power, and estimating the sugar with Fehling's solution. If the
latter indicates 15 per cent, of sugar, then if levulose alone were
present, the rotatory power (by sodium-light, in a tube 0*1 metre

f

1 See Hesse, Annal. d. Chem. und Pharm. clxxvi. 95, 1875, and Tollens,
Ber. d. d. chem. Ges. xi. 1800.

2 Ber. d. d. chem. Ges. x. 827, 1877.

§ 210. ESTIMATION BY POLARIZATION. 223

long) should be - 15° ( = 15 x I'O),1 and for dextrose alone 7*96°.
Supposing now the angle of rotation observed to have been
-5-202°, that is -9 798° less than levulose alone, the amount
of the latter present can be calculated from the statement

2883-3: 1883-3:: 9*798 :x

where 2883 -3 is the difference between the rotation-constants of
grape- and fruit-sugar j 1883-3 -(- 1000") {, and 1883-3 the con-
stant of grape-sugar \ multiplying out

-6-4

which is the percentage of levulose, leaving 15 -0-6 '4 = 8 "6 per
cent, of dextrose.

§ 210. Cane- and Invert-sugar. — A similar course may be pursued
in other cases involving the simultaneous estimation of two sugars.
For cane- and invert-sugar, as they occur for instance in beet-juice,
it is usual to determine the rotatory power both before and after
inversion with a dilute acid. If cane-sugar is present, more invert-
sugar will be found than would correspond to the rotatory power
first observed,

According to Haughton,2 the rotatory power of mixtures of cane-
and invert-sugar cannot be correctly determined unless the excess
of the basic acetate of lead, used to clarify the solution, is first
removed. He thinks that the lead forms a dextro-rotatory
compound with levulose. Such solutions containing lead are
also said to yield inaccurate results with Fehling's solution.

If the use of basic acetate of lead alone is insufficient to render
such liquids as beet- juice, etc., clear and colourless enough for
examination in the polariscope, it may sometimes be advantage-
ously combined with solution of alum. It is frequently undesirable
to decolourize with charcoal, as that is capable of retaining some
of the sugar.

The presence of asparagine can be the source of considerable
error : firstly, because that substance is itself optically active ; and
secondly, because its ^rotatory power varies as the solution is acid
or alkaline. Moreover, it is resolved, by boiling with hydrochloric

1 Calculated from equation a= jj~. Neubauer takes the rotatory power of
levulose to be - 100° instead of - 106°.

2 Journ. Chem. Soc. ix. 85; Zeitschr. f. anal. Chem. x. 490, 1871.

224 GLUCOSES, SACCHAROSES, ETC.

acid, into aspartic acid and ammonia ; the former of which is
lievo-rotatory in alkaline solution, but dextro-rotatory in acid.

Asparagine is not precipitated by basic acetate of lead, by lime,
or by baryta ; and although aspartic acid is thrown down by lead
salts, yet the precipitate is redissolved by an excess.1

§ 211. Estimation of three Sugars. — Dupre2 and Apjohn3 have
made the estimation of cane-, grape-, and fruit-sugar in the same
solution, the subject of investigation. As their methods, how-
ever, involve a combination of optical and volumetric determina-
tions in which accuracy is required in ascertaining the amount of
grape- and fruit-sugar present, especially in titrating, I am afraid
their processes will at present yield only approximate results. I
have already shown (§ 85) that the volumetric estimation of
glucose in the presence of cane-sugar is not so accurate as might
be wished.

§ 212. Mannite. — Of mannite (cf. § 91) it may be here observed
that one part dissolves in 6'14 to 6 '21 of water at 15°, and in 5*12
to 5*38 at 20°. One part requires also 1515 of absolute alcohol
at 17* for complete solution. Although optically inactive, as
previously stated, it is dextro-rotatory when dissolved in a con-
centrated solution of borax. It melts at 166°, and is converted at
200° with loss of water into mannitan. With moderately strong
nitric acid it yields principally mucic and saccharic acids ; with the
strongest acid, nitro-mannite. It is said (according to Biegel) to
reduce gold and silver salts, but not alkaline copper solution, when
warmed for a short time. Mannite prevents, however, the preci-
pitation of hydrate of copper.

1 On saccharometry, and especially the estimation of invert-sugar when
accompanied by cane-sugar, as in beet-juice, crude sugar, etc., see Ventzke,
Journ. f. pract. Chem. xxv. 65, xxviii. 101 ; Kleinschmidt, Dingler's polyt.
Journ. clxxxi. 306, 1867 ; Anders, ibid, clxxxii. 331 ; Bodenbender,
Zeitschr. f. Chem. N. F. ii. 222, 1867 ; Sostmann, ibid. 480. The latter
authors draw special attention to the influence that lime exercises on the
results of optical determinations of cane-sugar. The influence of asparagine
and aspartic acid has been observed by Dubrunfaut (Dingler's polyt. Journ.
cxxi. 305) and Scheibler, ibid, clxxxi. 415). Communications by Scheibler on
the errors in optical estimations have appeared in the Zeitschr. f. Chem. N. F.
iii. 617, and Zeitschr. f. anal. Chem. viii. 211, 1869. See also Stammer,
Dingler's polyt. Journ. clxxxii. 160 ; Dubrunfaut, ibid. cxxi. 299, clxxxv. 231 ;
Landolt, Zeitschr. f. anal. Chem. vii. 1, 1868. On the influence of asparagine,
see lastly also Champion and Pellet, ibid. xvi. 120, 1877.

2 Chem. News, xxi. 97, 1870,

3 Ibid. p. 86. See also Zeitschr. f. anal. Chem. ix. 499, 501, 1870.

§ 213. QUERCITE, ETC. 225

Dukite, or melampyrite, is isomeric with mannite, and shares
most of its important properties. The crystals of the former
belong to the monoclinic system, those of the latter to the rhombic.
Dulcite dissolves in three parts of cold water, is optically inactive,
does not ferment, and melts at 182°.

Isodulcite (rhamnodulcite) is also isomeric with the foregoing.
Crystals of isodulcite melt at 93° to 94°, dissolve in 2 -09 parts of
water at 18°, and also in absolute alcohol. It is not fermentable,
but reduces Fehling's solution, and is dextro-rotatory, (r/)y=8'4°.

Hesperidin-sugar and sorbite are also said to be isomeric with
mannite. The former crystallizes in the monoclinic system, is
dextro-rotatory, sparingly soluble in hot absolute alcohol, but
more easily in hot 70 per cent, spirit. It melts at 70'5° to 76°,
and slowly reduces Fehling. Anhydrous sorbite melts at about
110°, and does not reduce Fehling.1

§ 213. Quercite, etc. — Quercite and pinite are isomeric with
mannitan and dulcitan and are sweet to the taste.

Quercite crystallizes in the monoclinic system, dissolves in 8 to
10 parts of cold water, is dextro-rotatory ( + 33'5°), and melts
at 235°.

Pinite is indistinctly crystalline, freely soluble in cold water,
and somewhat soluble in dilute spirit ; it melts at 150°, and has
a dextro-rotatory power of 58 '6°.

Abietite differs from the foregoing in containing the elements
of a molecule of water less ; it has been the subject of commu-
nications by Rochleder. 2

ACIDS.

§214. Detection of Acids. — In addition to the reaction of malic
«rid mentioned in § 81, Barfoed3 describes another depending upon
the conversion of the acid, at a temperature of 160° to 170°, into
maleic and fumaric acids, with production of a crystalline sublimate.
A third is the lime-reaction ; malate of lime requires the addition
of at least 1 to 2 volumes of spirit for precipitation; and when thus

1 Compare Boussingault, Journ. de Phann. et de Chim. xvi. 36, 1872
(Pharm. Journ. Trans. [3], iii. 28).

2 Journ. f. pract. Chem. cv. 63, and Apoth.-Ver. viii. 363, 1868. For
catharto-mannite, see Kubli and Dragendorff, Pharm. Zeitschr. f. Russland,
iv. 467, 1865, and Keussler, ibid. xvii. 363, 1878. For bergenite, see Morelle,
Chem. Centralblatt, 758, 1881 (Comptes rendus, xciii. 646).

3 Zeitschr. f. anal. Chem. vii. 403, 1868.

15

226 ACIDS.

thrown out of solution, softens on warming and aggregates to a
mass, which becomes granular and crystalline on cooling. The
magnesia-reaction, mentioned by the same author as a new one,
consists in converting into malate of magnesia either by saturating
the acid with oxide or carbonate of magnesia, or by mixing a con-
centrated solution of an alkaline malate with chloride of mag-
nesium. The salt is precipitated by spirit from a hot solution,
as a tenacious mass hardening on cooling. (Citrate of magnesia
behaves in a similar manner.)

Barfoed separates malic from oxalic (§ 219) and tartaric (§ 217)
acids by precipitating the last two from neutral solution by chloride
of calcium, and throwing out malate of calcium from the nitrate
by the addition of alcohol. If tartaric acid is present, it must be
remembered that the calcium-salt of this acid separates but slowly.
(See also. §218.)

In separating citric (§ 215) from malic acid the same chemist
takes advantage of the fact that citrate of calcium requires less
spirit for precipitation than malate.

If malic acid is in solution with oxalic, tartaric, and citric acid,
Barfoed advises the precipitation of the last three as neutral am-
monium salts by the addition of 7 to 8 volumes of 98 per cent,
spirit • after standing twelve to twenty-four hours the precipitate
is filtered off, and the malic acid thrown down in the filtrate with
acetate of lead.

Sucdnic acid (§ 220) can be separated from malic acid, according
to Barfoed, by converting into neutral alkaline salts, precipitating
with acetate of lead, dissolving the precipitate in acetate of ammonia
solution, and then separating the malate of lead by the additioi
of 2 volumes of spirit ; or the concentrated aqueous solutions of
the neutral potassium, or sodium-salts, may be mixed with aboul
6 volumes of spirit, when the succinate remains in solution.

For the separation of malic acid from gallotannic (§§ 49 et seq.
and 165), gallic (§ 151), benzoic (§ 26), acetic and formic (§ 139]
acid, reference must be made to the original work.

To remove sulphuric and phosphoric acids from solutions in which
malic acid is to be detected, Barfoed recommends separating the
first two by the addition of chloride of barium to the hot solution,
and precipitating the malate of barium from the filtrate by the
addition of alcohol.

§ 215. Estimation of Citric Acid. — In estimating citric acid, Crei

§§215, 216. CITRIC ACID. 227

takes advantage of the insolubility of the barium-salt in spirit.
To a neutral solution of the citrate a solution of acetate of barium
and 2 volumes of spirit are added. The precipitate is filtered
off, ignited, converted into sulphate by sulphuric acid, and weighed
as such. The composition of citrate of barium is said to be
Ba3C,,H10014. (Compare Zeitschr. f. anal. Chem. xi. 446, 1871.)1

Precipitation by barium had been previously recommended by
Kammerer as a means of detecting citric acid. 2 If to a solution
of a citrate excess of acetate of barium is added, a voluminous
precipitate is obtained, which gradually becomes crystalline
(prisms) when heated for several hours on the water-bath. The
presence of other fruit-acids does not interfere. If the solu-
tion is very dilute it must be concentrated after the addition of
the barium salt, as otherwise only acicular crystals are produced.
See further §§218 to 220.

§ 216. Qualitative Reactions of Citric Acid. — Sarandinaki has
drawn attention to the fact that the triethylic ether of citric acid
decomposes when heated in sealed tubes to 110°, with separation
of a blue powder;3 and that an aqueous solution of citrate of
ammonium, similarly treated for six hours, also deposits a blue
decomposition-product on subsequent exposure to air and light in
a flat dish. Sabanin and Laskowsky4 have shown that neither
tartaric, malic, nor oxalic acid interferes with the reaction which
succeeds with O'Ol gram of citric acid. Aconitic acid comports
itself like citric. If the juice of a fruit or a vegetable infusion is
under examination, the citric acid can be precipitated as citrate of
lead, the latter converted into citrate of barium, and finally into
citrate of ammonium, which can be tested as above described.

It may also be observed that an aqueous solution of citric acid
is optically inactive. According to Eoennefahrt, 100 parts of
ether dissolve 10 parts of the crystallized and 13 of the anhydrous
acid, and can remove as much as 3 -6 parts when shaken with an
aqueous solution ; facts scarcely in accordance with the statement

1 For quantitative estimation of tartaric acid, see also Inette, Comptes
rendus, Ixvi.' 417, 1868.

2 Annal. d. Chem. und Pharm. cxlviii. 294, and Zeitschr. f. anal. Chem.
viii. 298, 1869.

3 Ber. d. d. chem. Ges. 1100, 1872. Compare also Kammerer, ibid. 736,
1875 (Journ. Chem. Soc. xxix. 496, xxviii. 1178).

4 Zeitschr. f. anal. Chem. xvii. 73, 1878 (Year-book Pharm. 165, 1878).

15—2

228 ACIDS.

formerly made to the effect that citric acid was difficultly soluble
in ether.

§ 217. Precipitation of Tartaric Acid (§ 82). — As early as 1864,
Berthelot and de Fleurieu precipitated tartaric acid by converting
it into acid tartrate, and adding 5 volumes of ether-alcohol.1
Jokisch and Bolley2 have shown that acid tartrate of calcium may
be simultaneously thrown down.

For the estimation of the total acid in must, see Pasteur. 3

Martenson4 precipitates tartaric acid from a 1 per cent, aqueous
solution of normal tartrate of potassium by the addition of chloride
of calcium and lime-water. The sides of the porcelain dish in
which the operation is performed should not be touched by the
stirring-rod. On standing for several hours, the calcium-salt
separates in crystals, and can be filtered off, washed with 80 to
85 per cent, spirit, dried at 100° and weighed; its composition is
then CaC4H406, 4H20.

§ 218. Estimation of Tartaric and Citric Acid. — Fleischer recom-
mends the separation of the former as acid tartrate of potassium,
the precipitation being rendered complete by the addition to the
solution of twice its volume of 95 per cent, spirit. The acid
tartrate is filtered off, redissolved, and estimated by titration with
normal alkali (§ 82).

The citric acid is precipitated from the filtrate by neutral acetate
of lead, washed with spirit of about 45 to 50 per cent., liberated
by sulphuretted hydrogen, and estimated by titration with normal
alkali.

This method is directly applicable if the acids are present in
the free state, or in combination with alkalies. 5

1 Comptes rendus, Ixxvii. 394.

2 Dingler's polyt. Journ. clxxxiii. 47, 1867 (Amer. Journ. Pharm. xxxvi. 60).
See also Kissel, Zeitschr. f. anal. Chem. viii. 409, 1869.

3 Zeitschr. f. anal. Chem. viii. 86, 1869.

4 Pharm. Zeitschr. f. Russland, viii. 23, 1868 (Amer. Journ. Pharm. xli. 335).

5 See also Schnitzer, Dingler's polyt. Journ. clxiv. 132, 1862, on the separa-
tion of tartaric from citric acid as acid tartrate.

Should it appear desirable to estimate the citric acid directly, after removal
of the tartaric as acid tartrate of potassium, the filtrate may be mixed with
chloride of calcium and concentrated by boiling. The citrate of calcium that
separates after adding lime-water should be filtered off hot, washed with boil-
ing water, dried and weighed (258 parts of the dried salt indicate 192 of citric
acid). See also Allen, Zeitschr. f. anal. Chem. xvi. 251, 1877.

For distinctive characters of tartaric and citi'ic acid, see Archiv d. Pharm.
clviii. 206, 1861 ; Chapman and Smith, Laboratory, April, 1868 ; Wimmel,
Zeitschr. f. anal. Chem. vii. 411, 1868.

§ 218. TARTAEIC AND CITRIC ACID. 229

If the solution contains oxalic and sulphuric, in addition to
tartaric and citric acids, all of them must be precipitated with
acetate of lead (which would also throw down part of any chlorine
that may be present); the precipitate should be washed with
dilute spirit and treated with ammonia (free from carbonate),
which dissolves citrate and tartrate of lead and part of the
chloride. The tartaric acid may be estimated in the solution by
decomposing the lead-salts with sulphide of ammonium and acetic
acid, filtering, and precipitating with acetate of potassium as above
described. If chloride is present, the citric acid must be subse-
quently-precipitated from a hot solution, either as lead-salt by
excess of acetate (washing with dilute spirit) or as calcium-salt
in the presence of spirit ; the latter must be redissolved in acetic
acid, and precipitated with acetate of lead.

If lime and phosphates are also present (in hydrochloric acid
solution), they may be precipitated by acetate of ammonia as
oxalate of calcium and phosphate of iron, and washed with solu-
tion of chloride of ammonium to avoid loss of tartaric acid as
acid tartrate of calcium. The phosphoric acid may be subse-
quently precipitated as phosphate of lead, which is insoluble in
ammonia. The residue of the lead precipitate, after treatment
with ammonia, can be decomposed by sulphide of ammonium, and
in the filtrate from the sulphide of lead, phosphoric, sulphuric, and
oxalic acids determined by the usual processes.

Malic acid if present would be precipitated together with the
citric acid as calcium salt ; the former, however, is soluble in
boiling lime-water.

Racemic acid would be thrown down with the tartaric acid, but
could be separated by dissolving the acid tartrate and racemate
in hydrochloric acid, supersaturating with ammonia and adding
chloride of calcium, which, under these conditions, precipitates
racemate of calcium only. x

Eacemic acid is optically inactive, whilst tartaric acid is dextro-
rotatory («)D = + H'18°(_p = 5), or(a)D = + 12 -80° (p = 15). It is
well-known, however, that racemic acid can be made to yield
Icevoracemic acid by suitable treatment.

For detection of tartaric acid in presence of malic, formic acids, etc., see
Braun, Zeitschr. f. anal. Chem. vii. 349, 1868 ; Kammerer, viii. 300, 1869.
See also Cailletet, xvii. 499, 1878 (Year-book Pharm. 150, 1878).

1 Compare Fleischer, Archiv d. Pharm. [3], v. 97, 1874 (Journ. Chem. Soc.
xxvii. 1181).

230

ACIDS.

Both tartaric and racemic acids are easily soluble in water and
alcohol. See also §§ 219, 220.

§219. Separation of Oxalic Acid. — Of the acids above referred
to, oxalic acid (§§81, 214, 216, 218) splits up, when heated, into
water, carbonic acid, and carbonic oxide without separation of
carbon. It undergoes a similar decomposition when warmed with
concentrated sulphuric acid. In addition to the reactions already
described, it must be observed that a neutral solution of an oxalate
throws down bright yellow crystalline ferrous oxalate, when warmed
or allowed to stand, with a solution of a ferrous salt. According
to Barfoed,1 the precipitate is soluble in about 4,000 parts of cold
water, but tolerably easily in solutions of oxalates, tartrates, and
citrates of the alkalies. The reagent must therefore be added in
sufficient quantity to convert the whole of the vegetable acids
present into salts of iron.

Tartaric acid, if present, might also yield a crystalline precipitate,
but the colour would be dirty-white and the crystals would be
distinguishable under the microscope ; it might be separated by
cold, very dilute hydrochloric acid, in which the oxalate is almost
insoluble. Citric acid delays the precipitation, and frequently
prevents the formation of characteristic crystals, which, however,
may be obtained by dissolving in a little warm hydrochloric acid
and neutralizing with ammonia.

Oxalic acid can be isolated from oxalate of calcium (§ 110) for
the purposes of further identification by dissolving in hydro-
chloric acid, and adding sufficient sulphuric acid to convert into
sulphate, which can then be completely precipitated by the
addition of an equal volume of spirit. Or the oxalate may be
dissolved in the smallest possible quantity of dilute nitric acid, pre-
cipitated with nitrate of lead, and liberated from the lead-salt by
sulphuretted hydrogen. (Of. §§ 81, 218, 220, where the estimatioi
of oxalic acid is discussed.) Oxalic acid requires 10 parts of cold
water for solution, but only 2 parts of alcohol.

§ 220. Succinic Acid (§ 214) is also one of those organic com-
pounds that are not blackened by concentrated sulphuric acid,
and leave no carbonaceous residue when heated on platinum foil,
or in a test-tube. In the latter case the major part is volatilized
without decomposition. It differs from oxalic acid in being less
soluble in cold water (about 1 in 15 at 20°), and in being spar-
1 'Lehrb. d. org. qual. Analyse,' Copenhagen, 1880.

§ 220. SUCCINIC ACID. 231

ingly dissolved by alcohol, and to but a very slight extent by
ether. The occurrence of succinic acid is frequently mentioned
in plant-analyses of less recent date, but in many instances confir-
mation of such statements is required. And even if that were
forthcoming, the question might be raised as to whether the acid
had not been produced by a process of fermentation that might
have taken place during the manipulation.

The following reactions may serve for the identification of
succinic acid :

" Chloride of barium precipitates from a solution of an alkaline
succinate (in presence of alcohol) a crystalline barium- salt, which
is soluble in about 250 parts of water, but almost insoluble in
alcohol. Hydrochloric acid dissolves it, but acetic acid takes up
only small quantities at the ordinary temperature.1

Chloride of calcium also throws down a crystalline salt from
concentrated solutions of alkaline succinates. The precipitate
dissolves, according to Barfoed, in about 50 parts of water, but is
very sparingly soluble in alcohol. If the precipitation takes place
in the presence of alcohol the salt is at first amorphous, and subse-
quently assumes a crystalline condition. It dissolves in warm
dilute acetic acid, and in boiling solution of chloride of ammonium.
(Distinction from oxalic acid.)

Succinate of lead is likewise crystalline, but complete separation
takes place very slowly. Basic acetate of lead throws down an
amorphous salt. Ferric chloride produces brownish-red amor-
phous precipitates in solutions of normal alkaline succinates, but
does not form insoluble compounds with oxalates.

In separating oxalic from succinic acid advantage may be taken
of the solubility of ammonium succinate in spirit. Barfoed
separates tartaric from succinic acid in the form of acid tartrate of
potassium in the presence of hydrochloric acid and alcohol. Or
it may be precipitated by mixing the hot solution with chloride
of ammonium, adding chloride of calcium and cooling. Citric acid
may be separated in a similar manner, but in this case the mixture
must be boiled until the whole of the citrate of calcium has been
thrown down; or the solution may be boiled with chloride of
barium and filtered whilst hot from the precipitated citrate of
barium. The filtrate contains the succinate of barium, which can
be thrown down by alcohol after cooling (§ 215).
1 See Barfoed, loc. tit.

232 ACIDS.

For the separation of malic acid, see § 214.

§ 221. Fumaric acid can also be sublimed, and, like oxalic and
succinic acids, yields a precipitate with acetate of lead that
gradually assumes a crystalline condition (§§ 81, 214). It
differs from malic acid in its slight solubility in water (according
to Lassaigne about 1 in 260 at 17°). It is much more easily
soluble in hot water, and is also dissolved by ether and by cold
spirit. The solubility of the silver-salt is extremely slight ;
manganous fumarate is also sparingly soluble in water, but freely
in spirit. The acid potassium and acid ammonium salts are not
very soluble in water, and scarcely at all in cold 80 per cent,
spirit. Lime-water does not precipitate fumaric acid.

Maleic acid is isomeric with the preceding, and, like it, is op-
tically inactive and yields a crystalline lead-salt. It is freely
soluble in water, but cannot be sublimed without decomposition.

Kinic acid may also be mentioned here. It is precipitated by
ammoniacal, but not by normal acetate of lead ; and when
saturated with milk of lime, yields at first a calcium-salt soluble
in water.

Many other vegetable acids can be separated from kinic acid
by precipitation with normal acetate of lead ; the filtrate, after
removal of the excess of lead as sulphide, can be freed from
sulphuretted hydrogen, boiled with milk of lime, concentrated,
and allowed to stand, when a crystalline deposit of kinate of
calcium will gradually separate, or more rapidly if spirit is added.
The presence of kinic acid in the deposit may be demonstrated
by heating with sulphuric acid and black oxide of manganese ;
the quinone thus produced is volatile, crystallizes in yellow
needles, and can be detected even in traces by its iodine-like
odour (§167, arbutin).

Kinic acid and its silver-salt are easily soluble in water.1

§ 222. Lactic Acid. — Although the occurrence of lactic acid in
living plants has not been placed beyond doubt, we must devote
a few lines to it here, as it is frequently produced from cart
hydrates when vegetable infusions are allowed to stand, and is
therefore often met with in plant-analysis. It can be detected by

1 For rubickloric acid, which occasionally accompanies kinic acid and, like
it, is only precipitated by alkaline acetate of lead solution, see Schwarz,
Sitzungsber. d. Akad. d. W. in Wien Math. nat. 01. 26, 1852. Rubichloric
acid is decomposed with simultaneous separation of green insoluble chlorrubin
when its aqueous solution is boiled with dilute hydrochloric acid.

§§ 222, 223. LACTIC AND GLYCOLIC ACID. 233

shaking the aqueous liquid with ether. On evaporating the
ethereal solution, it is obtained in the form of a syrup, easily
soluble in water and in alcohol. Both the calcium and lead salts
are freely dissolved by water, the former requiring about 10 parts
at the ordinary temperature. Lactic acid can thus be separated
from many other acids by precipitation with acetate, or, if free
acids are present, by digestion with carbonate of lead or calcium.
Lactate of calcium is further soluble in boiling 85 per cent, spirit,
and crystallizes from hot saturated spirituous and aqueous solu-
tions on cooling.

From a spirituous solution of lactate of lime ether throws down
an amorphous precipitate, which gradually becomes crystalline.1

The magnesium and zinc salts are also crystalline ; the former
is best prepared by precipitating a concentrated solution of lactate
of soda with chloride of magnesium in the presence of alcohol ;
the latter is frequently of use in detecting lactic acid. Lactate
of magnesium requires about 30 parts of cold water for solution,
of zinc about 60 ; both are far more easily soluble in hot water.
If the presence of lactic acid is suspected, the aqueous solution
should be concentrated, digested hot with oxide of zinc, cooled,
and examined under the microscope. It should show bundles of
needles and sphaerocrystalline masses, as well as four-sided prisms
and wedge-shaped crystals. Paralactate (sarcolactate) of zinc is
much more easily soluble, requiring only about 6 parts of cold
water. Acicular crystals are also obtained if carbonate of silver
is used instead of oxide of zinc ; they are soluble in alcohol.

Air-dry lactate of calcium contains 29*2 per cent, of water and
1 8 *3 per cent, of oxide of calcium.

The zinc-salt contains 18 -2 per cent, of water and 2 7 -3 per
cent, of oxide of zinc.

§ 223. Gly colic Add. — Gly colic acid is homologous with lactic
acid, and resembles it in many of its properties. It has been
found in the juice of unripe grapes. Ethereal solutions yield the
acid in crystals which melt at 78° to 79°, and are partially
volatile in the vapour of water without decomposition. Glycolate
of barium dissolves in 7 -9 parts of cold water, of calcium in 80 '8,
of zinc in 31'6, of lead (normal salt) in 31-17. The last three
can be obtained in crystals. The precipitate produced by basic
acetate of lead is very sparingly soluble (about 1 in 10,000), and

1 Compare Barfoed, loc, cit. 144.

234 ALBUMINOIDS.

can therefore be made available for the separation of the acid ;
the basic lead-salt can be converted into the normal by the action
of dilute nitric acid. Glycolic acid can be isolated by shaking
with ether. Its calcium-salt contains 2 3 '09 per cent, of oxide of
calcium, its normal lead-salt 62-48 per cent, of oxide of lead.

ALBUMINOIDS, ETC.

§ 224. Estimation. — In § 96 the albuminoids have been estimated
by multiplying the nitrogen found by 6 '2 5. This calculation is
based upon the assumption that albuminoid substances contain
16 per cent, of nitrogen.1 Attention has, however, been frequently
drawn to the fact, that most albuminous substances contain more than
16 per cent, of nitrogen; those of cereals, leguminous fruits, etc.,
can be estimated to contain at least 16*60 per cent. ; the factor 6*0
has therefore been recommended in such cases as preferable. But
even then the results obtained will be too low if the material
under examination contain much conglutin or gliaclin2 (as, for
instance, lupin seeds, almonds, brazil-nuts, wheat, etc.), as
conglutin contains 18*4, and gliadin (§235) 18'1 per cent, of
nitrogen. When, therefore, large quantities of those bodies are
present, Eitthausen advises multiplying by 5 -5.

§ 225. Legumin. — If the experiment described in § 93 has shown
the presence of legumin (vegetable casein), the maceration should
be repeated in the cold (best at a temp, of 4° to 5°) for about
five hours, the clear liquid decanted off, and the maceration

1 It was formerly assumed that they contained 15 6 per cent, of nitrogen,
and the amount of the latter was therefore multiplied by 6'33. That the
nitrogen found in alkaloids, albuminoids, etc., by the method of Varrentrapp
and Will is too low has already been shown by V. d. Burg (Zeitschr. f. anal.
Chem. iv. 322, 1865), Nowak (ibid. xi. 324, 1871), and Seegen and Nowak
(ibid. xii. 316, 1873 ; xiii. 460, 1874). Meusel expresses himself to the con-
trary (ibid. v. 197, 1866). Marcker has shown (Annal. d. Landwirthsch. xii.
619) that the error is not so large if the soda lime used is free from magnesia.
See also Kreusler (Zeitschr. f. anal. Chem. xii. 354, 1873) ; Marcker (ibid
221) ; Marcker und Abesser (ibid. 447) ; Johnson (ibid. 446) ; Eitthausen
(ibid. xiii. 240, 1874) ; Settegast (ibid. xvii. 501, 1878). On the estima-
tion of nitrogen, see also Nowak (Zeitschr. f. anal. Chem. xii. 102, 1873) ;
Makris (ibid. xvi. 249, 1877) ; Habermann (ibid. xvii. 376, 1878) ; Pfliiger
(Archiv. f. ges. Phys. xviii. 117, 1879) ; Hanko (Ber.d. d. chem. Ges. xii.
451) ; Schiff (Annal d. Chem. und Pharm. cxcv. 293) ; Kitthausen (Zeitschr.
f. anal. Chem. xviii. 601, 1879).

2 Compare Eitthausen, Die Eiweisskorper der Getreidearten, Hulsenfrlichte
etc., 237, Bonn, 1872.

§ 226. EXTRACTION WITH DILUTE ALKALI. 235

repeated once more. The legumin can then be precipitated as
described.1

During all these manipulations, the exclusion as far as possible of
the carbonic acid in the air is most strongly to be urged. It would be
liable, in most cases, to cause an error by partially or completely pre-
cipitating albuminoids allied to (perhaps identical with) legumin,
such as globulin, or vegetable vitellin.

If the material has not been previously entirely freed from fixed
oil (and this is nob always possible with petroleum spirit) the
precipitated legumin must be finally washed with absolute alcohol
and with ether, to remove the oil mechanically retained by it.

§226. Extraction with Dilute Alkali. — Ritthausen has observed
that the strongly acid reaction of many freshly powdered seeds
decreases on keeping. Now strongly acid liquids are less suitable
for the extraction of legumin than neutral or alkaline ; Weyl,2
moreover, asserts that fresh seeds contain no legumin, and ex.
presses it as his opinion that this substance is produced from
vitellin and myosin during the manipulations. The differences
that can thus arise are extremely inconvenient. It must also be
observed that pure water frequently extracts but very small
quantities of legumin from vegetable substances containing that
body, and that the major part is removed only by dilute alkali.
This portion of the legumin (casein,3 glutencasein, conglutin,
vegetable fibrin) will therefore be dissolved when the residue in-
soluble in water is treated with dilute (O'l to 0'2 per cent.) soda
or potash (§§ 103 to 106). If the presence of legumin is suspected
it is advisable to extract at a temperature of 4° to 6°. (See also
§ 233.)

Should metardbic acid (§ 195) and legumin be extracted together,
a total estimation must first be made, and the nitrogen then de-
termined in a part of the precipitate, from which the amount of
legumin present can be calculated.

A current of carbonic acid might be passed through the alkaline
extract to ascertain whether globulin (vitellin, myosin) can be thus
precipitated (§ 93) ; should this prove to be the case, it might be

1 Compare Ritthausen, loc. cit. 144.

2 Beitr. z. Kenntniss d. thier. und pflanz. Eiweisskorper. Diss. 1877.

3 The substances here referred to agree in most of their properties, but
exhibit certain differences ; thus, glutencasein contains more sulphur, and is
more easily soluble in acetic acid than legumin. Ritthausen advocates the
use of the word 'casein' as a group-designation.

236 ALBUMINOIDS.

rapidly filtered off with the help of a filter-pump, washed with 40
to 50 per cent, spirit, finally with absolute alcohol and with ether,
dried and weighed.

§ 227. Isolation of Vitellin, etc. — Grains of vitellin1 (aleurone, etc.)
may be frequently isolated from substances containing them in
large quantities, by a process of elutriation with olive oil,2 or a
mixture of oil and petroleum spirit.3 Freed from oil with
petroleum spirit, vitellin dissolves in water at 30° to 40°, and can
be precipitated from such a solution by a current of carbonic acid.
To obtain it in crystals the precipitate is digested with calcined
magnesia at 35°, filtered whilst warm and cooled. Schmiedeberg
considers these crystalloids, as well as aleurone itself, to be
compounds of vitellin with alkalies or alkaline earths. The
crystals are doubly refracting.

§ 228. Separation of Vitellin from Myos'm. — According to Weyl,'1
vegetable vitellin may be distinguished from vegetable myosin by
requiring, in a solution containing 10 per cent, of common salt, a
temperature of 75° for coagulation, whilst myosin coagulates at
55° to 60°. The latter, which has also been found in potatoes,
passes into solution when the residue, after treatment with water,
is macerated with 10 per cent, solution of salt. Small pieces of
rock-salt suspended in such a solution (previously neutralized with
carbonate of soda) cause the gradual precipitation of the myosin,
which, however, can be redissolved by the addition of a little
water. Myosin may be separated from vitellin by diluting the
solution largely with water, precipitating both with carbonic acid,
dissolving in dilute salt-solution and coagulating at the tempera-
ture stated.

§ 229. Estimation. — Experiments made by Liborius,5 Girgen-
sohn,6 and Taraskewicz,7 have shown that the albumen of blood-
serum, eggs, etc., can be estimated with tolerable accuracy by

1 A similar substance occurs in the seeds of Pinus cembra. See Schuppe,
Pharm. Zeitschr. f. Russland, 520, 1880.

2 Compare Maschke, Chem. Centralblatt, 864, 1858, and Sachsse, ibid. 583,
1876 (Journ. Chem. Soc. xxxii, 200).

3 Compare Schmiedeberg, Zeitschr. f. phys. Chem. i. 206 ; Ritthausen,
Archiv f. die ges. Phys. xvi. 301 (Journ. Chem. Soc. xxxiv. 518).

4 Loc. cit.

5 '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. 237

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 tannin
will generally yield higher results than can be obtained by coagu-
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 acetic 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,
I do not recommend 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 may then be estimated by precipitation 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. If the chloride of sodium is omitted the precipita-
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, etc. ; 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
evinces 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 myronic acid, nor does invertin
convert starch into maltose and dextrin, etc. It is easy, there-
fore, to detect diastase in malt, invertin in yeast, emulsin in
almonds, etc., the presence of which is anticipated. The liquefaction
of starch-paste, the conversion of cane-sugar into invert-sugar, the
development of hydrocyanic acid and oil of bitter almonds, are
changes so striking and so promptly effected, that the qualitative
detection of the ferments producing them leaves nothing to be
desired. But the varied nature of the ferments themselves and
of their action renders it exceedingly difficult 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 tincture 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.1

If other substances are thrown down with the albumen the
nitrogen in the precipitate may be determined, and from that the
albumen present calculated. Bitthausen'2 and Taraskewicz 3 have
proved experimentally that the precipitate contains the whole of
the albumen, casein, etc.

§232. Estimation continued. — Sestini4 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
acetate corresponding to 4*55 grams of oxide had to be added.

" Loc. cit. 34, etc. ; Kltthausen and Settegast, Archiv f. d. ges. Phys. xvi.
293, 1877. See also Morner, Upsala Lakareforen. Forhandl. xii. 475, 1877
Fassbender, Ber. d. d. chem. Ges. xiii. 1818, 1880 (Journ. Chem. Soc. xl.
205).

3 Loc. cit.

4 Landwirthsch. Versuchsst. xx. 305, 1878 (Journ. Chem. Soc. xxxiv. 740).

§ 231. ESTIMATION. 239

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 water for an hour,
made distinctly acid with lactic acid, mixed with acetate of
lead, and filtered ; the insoluble residue is drietf 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 precipitation with
lead indicates the total albumen, both soluble and insoluble.

In addition to the foregoing precipitants, some of the group
reagents for alkaloids — phosphomolybdic, phosphotungstic acid,
potassiomercuric iodide, etc. — also throw down albuminous sub-
stances (§ 63). Phosphotungstic 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

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, Eepert. 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
anticipated. 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. ) the separation is often very complete.
Peptones are precipitated, as above stated, by phosphotungstic 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

24,0

ALBUMINOIDS.

Precipitation by phenol and calculation from the nitrogen
contained in the precipitate has been recommended by Church 1 for
the estimation of the albuminoids in vegetable infusions, in the
presence of amides, etc.

My experience in precipitating albumen, etc., 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 alkali. The same is
the case with dilute acid (2-12 per cent. HC1), the substances
extracted being gluten, fibrin (§ 235), gliadin, mucedin, etc. 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 direction it
would appear that hydrochloric acid and pepsin dissolve more than
the former alone.2 In making such estimations I should recommend
100 cc. of water, 1 gram of 33 per cent, hydrochloric acid, and O'l

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. It is then 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 . cit.

- See Kessler, Versuche iiber die Wirkung des Pepsins auf einige animal,
u. vegetab. Nahrungsmittel. Diss. Dorpat, 1880.

§ 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. Extraction ivith Spirit. — 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). If the majority of
the spirit is distilled off from the clear liquor a second precipitate
will form, consisting principally 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.1 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-

1 The spirit dissolves a little fjlutenfibrin, which can subsequently be precipi-
tated by ether.

16

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.1 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 (acetic, citric, 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.2

Gliadin is characterized by its tough, slimy consistency. 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 precipitated 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 acetic 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, tartaric and oxalic acids.
Zander has recently reported on another albuminous substance soluble in
spirit ('Chemisches iiber die Samen des Xanthium Strumarium.' Diss.
Dorpat, 1881).

§§ 236, 237. GLUTEN, ETC. 243

In its other properties it agrees fairly well with gliadin. (Compare
also § 237.)

§ 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 cloth, 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,2 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.

§ 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-
cipitated 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 weighing, deducting the
acetate of soda present.

With regard to the latter, I may observe that it cannot be cal-
culated from the amount of soda used, but must be estimated by

1 Compare Archiv d. Phann. cxcv. 47, 1871.

2 Journ. de Phann. et de Chim. [5], iv. 127, 1881.

16—2

244

AMINES.

incinerating a portion of the dried residue, and calculating 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 Substances. — 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 alcoholic
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.1

§ 240. For the separation of ethylamine from diethyl- and triethylr
amine by means of anhydrous ethyloxalate, see A. W. Hofmann f
the author subsequently availed himself of the method in separ-
ating the methyl bases. Carey Lea3 recommends picric 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 ethylic 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, Iv. 749, 1862.

3 Chem. Centralblatt, 76, 1863.

§241. ESTIMATION. 245

Triethylamine is not attacked by ethylic oxalate, and can be
separated from diethyloxamide and ethylic 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 crystalline methylethyloxamide and -the liquid
ethylic dimethyloxamate (B.P. 240° to 250°) by distillation.

§ 241. Estimation. — Sachsse and Kormann l have published a
method for the approximate estimation of amides, based upon their
decomposition by nitrous acid with liberation of nitrogen ; the

Fig. 10.

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. 10 and 11.
The generating vessel A is of about 50 to 60 cc. capacity, and
closed with an indiarubber cork bored with three holes ; through
these there pass two funnel-tubes, a and b, 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 et are also filled with water,
so as to displace the atmospheric 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
lulUes of air to adhere to the sides.

Fig. 11.

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 nitric 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*1 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-

§241. ESTIMATION. 247

ing in a pneumatic trough, should be capable of holding 50 to 60
cc., and be graduated to 0'2 cc. It is filled with the iron-solution
contained in B by opening the clip h and blowing through the
shorter bent tube in B ; by this means the solution can be run into
the pneumatic trough ; on opening / and sucking at g the solution
rises in the tube until it reaches and passes /, which should then
be closed.

After replacing 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 sufficient strong solution of ferrous sulphate ; this can be
ensured by frequently opening the clip h 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-
tibe through d. The delivery-tube is now removed, and the
vhole of the nitric 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 carbonic acid. When this
has been effected, the measuring-tube is lowered in the cylinder
until both liquids have the same level The volume of gas is now
read off, reduced to 0° and from it the amount of amide originally
present calculated, deducting 1 cc. as unavoidable error caused by
the atmospheric air mixed with the nitrogen ; 28 parts by weight
of nitrogen indicate 150 of crystallized asparagine, 131 of leucine,
and 181 of tyrosine. (§§ 191, 192).

§ 242. Amidic 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 precipitation, 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 precipitate 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 amidic acid present may be calculated.

Cathartic Acid occurs in senna, in the bark of Rhamnus frangula,
and probably also in rhubarb.1 It is a glucoside, yielding by its
decomposition sparingly soluble cathartogenic acid and 34*1 per
cent, of glucose. According to Kubly, cathartic acid2 contains
1*48 to 1*51 per cent, of nitrogen, cathartogenic acid 2*46 per
cent. The latter is easily produced by heating an aqueous solu-
tion of cathartic 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 witi
bases (the alcohol precipitate containing 4 to 5 per cent, of ash);
but in Ehamnus frangula it appears to occur, partly at least, in
the free state. It is a strong purgative.

Husson3 estimates the quality of a rhubarb by ascertaining
the amount of iodine an infusion is capable of absorbing; but
Greenish4 has shown that this method does not yield reliable
results.

Sclerotic Acid5 is a constituent of ergot, and contains about 4f2
per cent, of nitrogen, but no sulphur ; its activity is not destroyed
by acids, etc., if in contact with them for a short period only. In
solubility it resembles cathartic acid. Its action, when injected
subcutaneously into frogs and other animals, is that of a powerful

1 Compare Kubly, ' Ueber das wirksame Princip und einige andere Best,
d. Sennesblatter,' Diss. Dorpat, 1865, and Pharm. Zeitschr. f. Kussland, iv.
429, 465. On Ehamnus frangula, see also Pharm. Zeitschr. f. Kussland, 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 Khamnus frangula bark con-
tains less nitrogen.

3 Union Pharm. 99, 1875 (Year-book Pharm. 344, 1875).

4 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).

§ 243. STARCH, LICHENIN, ETC. 249

poison.1 It is precipitated by tannin and basic 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 sclerotic
acid appears to be converted into an allied substance containing
6 '6 per cent, of nitrogen, which has been named scleromucin. 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, it is not dissolved by
cold water, and not with facility by warm. It resembles sclerotic
acid in its action and other properties.

STARCH. LICHENIN, WOOD-GUM, ETC.

§ 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 §§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, s amylon (Bechamp) ; secondly, a substance character-
ized by its insolubility in cold water, solubility in saliva, etc., and
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 zinc into a substance that is tinged
blue by the same reagent.

Some years ago Nageli 2 stated that in his opinion there ex-
isted two different modifications of amylon, which he called blue

1 From 0'03 to 0'04 gram produces in frogs a swelling of the skin 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.

2 Annal. d. Chem. und Pharm. clxxiii. 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 colours 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, etc., 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, crystals
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, 7 amylon (B6champ), 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
hydrochloric 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-
quently noticed 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 a
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 in part, of the composition C12H22On, agreeing therefore
in this respect with arabic 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 zinc, is
a matter for further inquiry. If the treatment with the above
oxidizing mixture of chlorate of potash and nitric 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.1

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 effected 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 hydrochloric 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-

1 Compare Berg, ' Zur Kenntniss des in Cetraria islandica vork. Lichenins
und iodblauenden Stoffes,' Diss. Dorpat, 1872. From Berg's experiments it
would appear that the formula C6H10O5 would indicate the composition of
lichen-starch better than C12H22011 ; the same is true of lichenin.

252 CELLULOSE, LIGNIN, ETC.

rotatory fermentable 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,1 the gelatinizing constituent of many algse, 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 Sphserococcus lichenoides, by a carbo-
hydrate2 soluble in dilute hydrochloric acid, but differing from
pararabin (§ 112) in yielding glucose when boiled with an acid.

§ 246. Wood-gum. — Thomsen3 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 C6H1005,
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 precipitated 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 Isevo-rotatory. It differs
from lichenin in not possessing the power of gelatinizing, from
metarabin in not being dissolved (when dry) by O'l per cent
solution of soda.

A similar substance was obtained by Pfeil4fromparenchymatous
tissue (agreeing, however, in composition better with the formula
C12H22On, a hydrocellulose), by Treffner from mosses, and by
Greenish from algae.

CELLULOSES, LIGNIN, AND ALLIED SUBSTANCES.

§ 247. Celluloses, etc.— Fr£my and Terreil5 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, 1880
(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. cit.

5 Journ. de Pharm. et de Chim. vii. 241, 1868.

§ 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
nitric acid, are left associated with the cellulose.

The cuticular substance alone is said to be insoluble in a mixture
of 1 eq. of sulphuric acid with 4 eq. of water ; it can be isolated
by treatment with acid of that strength, followed by washing with
pure water and dilute alkali.

The incrustmg substances are estimated by difference.

In a more recent publication, the authors observe that the
following are the principal 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 (fungin) insoluble in ammonio-sulphate of copper.

All three modifications of cellulose are soluble in H9S04, 2H9O.
(Compare also § 248).

Vasculose> insoluble in H2S04, 2H2O, 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 H2S04, 2H2O, and in ammonio-sulphate of
copper, but soluble in alkalies under the ordinary pressure.

Pectose. convertible by acids into soluble pectin.1

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.' Stackmann2 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 uber die Zusammensetzung d. Holzes.' Diss. Dorpat, 1878.

254

CELLULOSE, LIGNIN, ETC.

an ultimate analysis of the material that had been thus treated,
both before 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 38-9 per
cent, of oxygen ; the majority of his results agree very well with
Fr. Schulze's1 (0 = 55-5, H = 5'8, 0 = 38-6); but German walnut
and mahogany show a little variation, probably due to the larger
amount of foreign substances they contain. All the dicotyledonous
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,2 at my suggestion, showed
that poplar wood contained 3*25 per cent, of wood-gum, mahogany
3'37, American walnut 4'56, 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 '5 6 per cent. 0,
4 '66 per cent. H, and 34 '80 per cent. 0. 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.

Koroll3 found the lignin of sclerenchymatous tissue (hazel-nut,
walnut) to contain from 51 -5 to 54 -2 per cent, of carbon, 4'8 to
5-5 per cent, of hydrogen, and 401 to 44 -7 of oxygen, and esti-
mated its quantity at 14 '3 to 15 '7 per cent. A substance re-
sembling wood-gum also occurs in the sclerenchymatous tissue of
nut-shells. Bast-fibres (lime and elm) yielded him 14'5 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 cuticular
substance,) chlorine-water extracted 11 per cent, of a substance
of an entirely different composition; viz. 0 = 727, H = 7'S,
0 = 19-4. (Cf. §250.)

1 'Beitr. z. Kenntniss d. Lignins.' Rostock, 1856.

2 Beitrage z. Chemie d. Holzgewebes. Diss. Dorpat, 1882.

3 ' Quant, chem. Unters. iiber d. Zusammensetz. d, Kork-, Bast-, Scleren-
chym. und Markgewebes.' Diss. Dorpat, 1880.

§ 247. SUBERIN. 255

The tissue of turnip, chicory-root, and elder-pith, which is
principally parenchymatous, yielded hardly anything to chlorine-
water. Pfeil also came to a similar conclusion with regard to the
tissue of apples. 1

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, etc. 2 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 difficult to remove completely by
digestion with chlorine-water. Nitric 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 chromic acid
more powerfully than lignin. Whether suberin really yields the
eerie 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. 3

For the microchemical characters of cutin, lignin, etc., see also
Vogl4 and Poulsen. 5 (See also § 249.)

The remarkably constant proportion existing between the
amount of cellulose and lignin, etc., 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 Loc. cit.

2 Compare Siewert, Zeitschr. f. d. ges. Naturw., xxx. 129; Journ. f. pract.
Chem. civ. 118, 1868. See also Hb'hnel, Sitz.-ber der phys. math. K. d. Akad.
d. W. in Wien, 1877 ; Bot. Ztg. 783.

3 Compare my ' Chem. Unters. eines an Betula alba vork. Pilzes.' Diss.
Petersburg, 1864.

4 Zeitsch. d. osterr. Apotheker-Ver. 1867, 16, 34, 60.

5 « Botanisk Mikrokemi.' Kjobenhavn, 1880.

256

CELLULOSE, LIGNIN, ETC.

as a special chemical compound (gluco-lignose, gluco-drupose of
Erdmann). Erdmann assumes that it is decomposed by hydro-
chloric acid with production of glucose, together with lignose or
drupose, and that with nitric acid it yields cellulose, whilst the
lignose or drupose undergoes further decomposition. Bente,1
who doubts the existence of gluco-drupose, shows that wood-cells
(? lignin) yield pyrocatechin when fused with potash.

§ 248. Cellulose. — The cellulose obtained from various plants
in the manner indicated does not appear to be invariably of the
composition C6H1005. That isolated by Stackmann from coni-
ferous wood was represented by the formula 5(C6H10O5) + H20,
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(C6H10O5) + 2H2O, whereas the wood of most dicotyledons
contains, according to Stackmann, a cellulose of the formula
5(C6H1005) + 3H20. In 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 nitric acid and chlorate
of potassium. Schuppe has shown that the action of the
sulphuric acid, the use of which I recommend to be discontinued,
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 C6H1005. But
the cellulose isolated from apples by a process that did not in-
clude treatment with sulphuric acid showed a deviation in com-
position from the formula C6H1005. 2

The cellulose of fungi (cf. § 249) frequently shows a com-
position corresponding almost exactly to the formula C6H1005.

§ 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. cxxxviii. 1, 1866, and Jahresb. 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,1 and reprecipitated
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 difficulty. Concentrated sulphuric acid and syrupy
solution of chloride of zinc render cellulose capable of assuming a
blue colour with iodine f but in some instances the reaction is
found to fail,3 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. 4

§ 250. Crude Fibre. — From what has been said of the isolation
of cellulose, it follows that the crude fibre of the physiologist and
agricultural 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 anticipate 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.5

1 I 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 8| 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. Eichter (Chem. Centralblatt, 483, 1881) has recently denied the
existence of a 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 ?

4 On cellulose see Pay en, Annal. d. Sciences naturelles, xi. 21, xiv. 88 ;
Fromberg, Annal. d. Chem. und Pharm. lii. 113 ; Heldt and Kochleder,
ibid, xlviii. 8; Schlossberger and Popping, 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 ; Koni^, Zeitschr. f. anal. Chem. xiii. 242,
1879.

5 Compare Holdefleiss, Zeitschr. f. Anal. Chem. xvi. 498, 1877, and
Landwirthsch. Jahrb. Supp. vi. 101.

17

258

PERCENTAGE COMPOSITION OF THE CONSTITUENTS

OF PLANTS MENTIONED IN THE FOREGOING

WORK.

NAME.

FORMULA.

C.

H.

0.

N.

S.

Abietic acid .

C^H^Og

78-57

9-52

11-91

Absinthiin

C40H58O9

70-38

8-50

21-12

Acetic acid .

C2H4O.7

40-00

6-66

53-33

Achilleine

C20H38N2b15

43-84

6-96

43-84

5-12

Aconitine

C33H43N012

61-39

6-67

2977

2-17

Aconitic acid .

C6H606

41-38

3-45

55-17

Adansonin

48-30

5-95

45-75

Aesculin

C2iH242Oi3

52-07

4-96

42-97

Albumin

52-45-

6-81-

22-21-

15-65-

0-8

53-97

7-77

23-50

15-92

Alizarin
Alkannin
Amanitine

C14H803
C15H1404
C5H14NO

75-00
69-72
57-69

3-57
5-42
13-46

21-44
24-86
15-38

13-46

Amygdalin
Amyrin

C20H27NOn
C25H420

52-51
83-49

5-91
11-79

38-52
4-73

3-06

Anacardic acid

^44^64^7 (?)

75-04

9-07

15-89

Anemonin

C15H1206 (?)

62-50

4-17

33-33

Anethol

C10H12O

81-08

8-11

10-81

Angelic acid .

C5H802

60-00

8-00

32-00

Antiarin

CTT f)
14±120U5

62-68

7-46

29-85

Apiin ....

C27H32016

52-9

5-2

41-9

Arabic acid .

42-10

6-43

51-47

Arachic acid .

C£H*<£

76-92

12-82

10-26

Arbutin

C TJ O14

53-7

6-1

40-2

Aribine
Aricine

d°3H90N4
C,3H26N264

78-43
70-05

5-68
6-59

16:25

15-89
7-11

Asclepin

C20H3403

74-54

10-56

14-90

Asparagin

C4H8N2Oa

36-36

6-06

36-37

21-21

Aspidospermine

C22H30N202

74-57

8-48

9-04

7-91

Athamantin .

Cf24H30O7 •

66-98

6-98

26-04

Atherosperrnine
Atropine

C30H10NA
O17M23JNU3

70-87
70-58

7-87
7-95

15-75
16-60

5-51

4-84

Barbalo'in
Bassorin

CC7lH0°0(?)

^12Jtl22(Jll

60-71
42-10

5-95
6-43

33-34
51-47

Beberine

Cj HytNOo

73-31

675

15-44

4-50

Benzaldehyde

C7fi60

79-24

5-65

15-11

Benzoic acid .

C7H602

68-85

4-92

26-23

Benzohelicin .

a0H20o8

61-86

5-15

32-99

Berberine

C,0H17N04

71-64

5-08

19-10

4-18

Betaine

C5H13N03

44-44

9-63

35-55

10-37

Betaorcin

C8H100,

69-56

7-24

23-20

Betulin ....

Co6H60O",

82-57

11-36

6-06

Bixine ....

c,8H34o;

74-66

7-55

17-78

Boheic acid .

C7H°°06

44-21

5-26

50-53

Borneol

77-92

11-69

10-39

Brasillin .

C H O-

67-11

5-43

27-46

Brucine

C23H26N.264

70-00

6-64

16-26

7-10

Bryonin

Q TJ Oig

60-00

8-33

31-66

Bryoidin

C20H3803

73-62

11-66

14-72

PERCENTAGE COMPOSITION OF CONSTITUENTS. 259

NAME.

FOKMULA.

C.

H.

0.

N.

S.

Butyl alcohol .

C4H100

64-80

13-51

21-62

Butyric acid .
Caffeine

C4H802

C8H10N402

54-55

49-48

9-09
5-15

36-36
16-51

28-86

Caffeo-tannic acid .

C14H1607

56-75

5-41

37-84

Cailcedrin

64-9

7-6

27-5

Caincin

|

58-24

7-38

34-38

Callutannic acid

C14H1409 (?)

51-53

4-30

44-17

Camphor

C10H16O

78-94

10-53

10-53

Cane-sugar

C]2H22On

42-10

6-43

51-47

Caoutchouc . .

C10H16

88-24

11-76

Capalo'in

QieHooOv (?)

59-26

6-17

34-57

Capric acid .

C10Ho0O2

69-76

11-62

18-61

Capric aldehyde

CioHaoO

76-92

12-82

10-26

Caproic acid .

C6H1202

62-07

10-35

27-58

Capryl alcohol

C8H180

73-84

13-84

12-32

Caprylic acid .

C8H1602

66-67

11-11

22'22

Capsaicin . .

C9H1402

70-00

9-29

2071

Cardol ....

CTT f\ /o\
o^Jlyo v/g ^. )

80-25

9-55

10-20

Carotin

C18H240

84-37

9-37

6-26

Carthamin

C14H1607

56*75

5-40

37-85

Carvol ....

C10H140

80-00

9-33

10-77

Caryophyllin .

78-94

10-53

10-53

Catechin

C19HlgOg

60-96

4-81

34-23

Catechu-tannic acid

C38JH[g4Oj5

62*46

4-66

32-88

Cathartomannite .

C6H1406

39-56

7-69

52-75

Cathartic acid

*>

57-57

5-12

34-96

1-50

0-85

Cellulose

C«H100B

44-44

6-17

49-39

Ceric acid

64-23

8-77

27-00

Cerotic acid .

C27H5402

79*02

13-17

7-81

Cerotyl alcohol

81-81

14-14

4-05

Cetraric acid .

C18H16O8

60-00

4-44

35-56

Cetyl alcohol .

C H O

78-68

13-95

7-37

Chelidonine .
Chelidonic acid

c$$f

68-06
45-65

5-08
2-17

14-32
52-24

12-54

Chlorogenine .

C21H20N04,H20

65-97

5-75

20-95

7-33

Chlorophyllan (1-37 P) .

j

73*4

9-7

9-57

5-62

Cholesterin .

C30H500

84-11

12-15

3-74

Cholin .

C5H15N02

49-59

12-39

26-44

11-57

Chrysarobin .

72*31

5-22

22-47

Chrysorhamnin

CooHjjoOij

58-23

4-64

37-13

Chrysophanic acid .

C"15Hi0O4

70-87

3-94

25-19

Chrysopicrin .
Cinchonine, Cinchonidine

C19H14Og (?)
C19H22N20

70-81
77-55

4-35

7-48

24'84
5-44

9-53

Cinchona-red .

C10H1407 (?)

53-33

5-19

41-48

Cinchona-tannic acid

n TT n m

v-'42-n60^'35 \'l

44-84

5-33

49-83

Cinchona-nova red .

61-01

5-15

33-64

Cinchona-no va tannic acic

C0 "H. "o 7

52*01

5-88

42-11

Cinnamein

CifiHiA

80<67

5-88

13-45

Cinnamic acid

C9H8Oo

72*97

5-41

21-62

Cinnamic aldehyde

C»H80

81-81

6-06

12-13

Citric acid

C6Hg07

37-50

4-17

58-33

Cnicin .

C4oH56O15 (?)

63-00

7-00

30-00

Cocaine

C16H19N08

66-44

6-57

22-15

4-84

Codeine

C18H01N03

72-24

7-02

16-06

4-68

Colchiceine .

C17H21N05

63-44

6-58

25-20

4-38

Colchicine

C17H23N06

60-53

6-82

28-50

4-15

Colocynthin .

C56H84023 (?)

59-78

7-47

32-75

Columbin

C21H22O7

65-28

5-69

29-03

17—!

260 PERCENTAGE COMPOSITION OF CONSTITUENTS.

NAME.

FORMULA.

C.

H.

0.

N.

S.

Conessine (Wrightine) .

?

78-3

11-2

?

?

Conglutin

9

50-24

6-81

24-13

18-37

0.45

Conhydrine .
Coniferin

C8H17NO

C16H2208

67-12
56-14

11-89
6-43

11-19
37-43

9-79

Coniine .

C8H N

76-81

12-00

11-20

Convallamarin

Co3H44O10

53-91

8-59

37 -50

Convallarin .

Co4H62Oii

63-16

9-60

27-24

Convolvulin .

C H O 6

54-87

7-37

3776

Coriamyrtin .

C20H2407

63-86

6-38

29-76

Coto'in .

C22H18O6

69-84

4-76

25-39

Crocin . . . . .
Crotonic acid .

C4H6°028

62-33
55-81

6-49
6-99

31-17
37-20

Cubebin

67-42

5-62

26-96

Cumarin

oXV

73-97

4-11

21-92

Cura§ao-alom

C15H1707

58-22

5-50

36-28

Curarine

C18H35N (?)

81-51

13-21

5-28

Curcumin

67-41

5-62

26:96

Cusconine

C23H26N204

70-05

6-59

16-25

7-11

Cyclamin

C20H34O10

55-29

7-83

36-87

Cyclopin
Cytisine

C14H18012
C20H27N30

44-44
73-85

476
8-31

51-80
4-92

12-92

Daphnin

52-39

478

42-83

Datiscin

C2;n22o!2

54-08

4-72

41-20

Delphinine

C22H35N06

64-55

8-66

23-47

3-42

Delphino'idine

C42H68N207

70-9

9-5

15-6

3-9

Dextrin ....

C6H1005

44-44

6-17

49-39

Digitalin

C5H802 (?)

59-95

8-05

32-00

Digitonin

C31H52017

53-21

7-60

39-19

Digitoxin

C21H3207

63-60

8-50

27-90

Ditaine ....
Dulcamarin .

C22HN04

U22±134U10

68-39
57-64

777
7-42

16-58
34-94

7-25

Dulcite .

C6H1406

39-56

7-69

52-75

Elaterin

68-96

8-04

23-00

Ellago-tannic acid .

Cj"4H10O10

49-69

3-16

47-25

Ellagic acid .

C H608

55-63

1-99

42-38

Eraodin .

C15H1005

66-67

370

30-63

Enmlsin

48-78

773

24-67

18-82

9

Ericolin

C34H56O01

51-00

7-00

42-00

Erythrite

C4H10O4

39-34

8-20

52-46

Erythrocentaurin .

Co7H9408

68-07

5-04

26-89

Ethyl alcohol .

CoHgO

52-17

13-04

34-79

Eugenin

C10"H1202

73-17

7-32

19-51

Eugenol

C10H12O2

73-17

7'32

19-51

Euphorbon

C15H240

81-82

11-04

7-14

Evernic acid .

C17H]607

61-44

4-82

33-74

Everninic acid

C9H1004

59-34

5-49

35-17

Ferulic acid .

61-23

6-12

32-65

Filicin ....

Co6H30O9

64-20

6-17

29-63

Frangulic acid

c;6H;2o5

67-6

4-2

38-2

Fraxin

C54Hg0O35

51-02

4-89

44-89

Fruit-sugar .

CgH^Og

40-00

6-66

53-33

Fumaric acid .

C4H404

41-38

3-45

55-17

Galactose
Galitannic acid

CfiH^Og

C7H8O5 (?)

40-00

48-84

6-66
4-65

53-33
46-51

Gallic acid

C7H605

49-49

3-65

46-86

Gardenin

C14H]206

60-85

4-75

34-40

Gelsemine

CnH19N02

67-00

9-64

16-30

7-10

Gentisin

65-11

3-87

31-02

PERCENTAGE COMPOSITION OF CONSTITUENTS. 261

NAME.

FOKMULA.

C.

H.

0.

N.

S.

Gliadin ....

9

52-60

7-00

21-49

18-06

0-85

Globularin

C30H44014

57-32

7-01

35-67

Glutencase'in .

?

51-0

6-7

25-4

16-1

0-8

Glycerin

C3H803

39-13

8-70

52-17

Glycolic acid .

C2H403

31-58

5-26

63-16

Glycyrrhizic acid .

C44H63NO18

59-12

7-05

32-66

1-17

Grape-sugar .

CgH10Og

40-00

6-66

53-34

Gratiolin

c OH".O

62-17

8-81

29-02

Gronhartin

C30H2606(?)

74-6

5-3

21-1

Gyrophoric acid

O TT r\

60-81

4-90

34-29

Haernatoxylin
Harmaline

v^o*

63-57
72-90

4-63
6-54

31-79
7-48

13-08

Harmine

C13HUN20

73-58

5-67

7-54

13-21

Hederic acid .

Cj5H0gd4

66-66

9-63

23-71

Helenin.

C21H;803

76-83

8-53

14-64

Helleborein .

52-35

7-38

40-27

Helleborin .

C fiH42Ofi

75-78

7-37

16-85

Heptyl-alcohol

C7H160

72-41

13-79

13-79

Hesperidin

C22H26O12

54-77

5-39

39-84

Hydrocarotin .
Hydrocyanic acid .

C18H300
CNH

82-44
44-44

11-41
3-70

6-15
51-85

Hydroquinone
Hyoscine

C6H602

C17H23N03

65-45

70-58

5-16
7-95

29-09
16-16

4-84

Hyoscyamine .

C17H23N03

70-58

7-95

16-16

4-84

Indican ....

C52H62N2034(?)

49-60

4-92

43-26

2-22

Indigo-blue
Inosite ....

C8H5NO
C6H1206

73-28
40-00

3-82
6-66

12-22
53-34

10-68

Inulin ....

C6H1005

44-44

6-17

49-39

Ipecacuanha tannic acid .
Isodulcite

cjfff

56-37
39-56

6-04
7-69

37-59

52-75

Jalapin ....

Jervine .

C27H47&208

56-66
61-03

777
8-56

35-57
25-27

5-14

Kampferid

?

64-48

4-40

31-20

Kinic acid

C7H1206

43-75

6-30

50-19

Kosiri ....

C31H38010

65-26

6-66

28-07

Lactic acid

C3H603

40-00

6-66

53-34

Lactucerin

81-81

11-04

7-14

Laserpitin

C24H3gO7

66-05

8-26

25-69

Laurocerasin .

C^HKoNO™

52-47

5-79

40-23

1-53

Laurostearic acid .

C12H2402

72-09

12-04

15-87

Lecanoric acid

C16H1407

60-37

4-40

35-23

Legumin

51-47

7-02

24-29

16-82

0-40

Levulin ....

C6H1005

44-44

6-17

49-39

Leucine ....

C6H13N02

54-96

9-92

24-43

10-69

Lichenin

C6H1005

44-44

6-17

49-39

Lichen -starch

C6H1005

44-44

6-17

49-39

Lignin (cf. p. 256) .

Limonin

C2gH30O8

66-38

6-48

27-23

Linin .

9

62-92

4-72

32-36

Lupinin (glucoside)

C29H32O16

54-63

5-47

39-90

Luteolin

C12H8O5

62-07

3-45

34-48

Maclurin
Male'ic acid .

cx^8

56-25
41-38

3-75
3-45

40-00
55-17

Malic acid

C4H605

35-82

4-48

59-70

Maltose

42-10

6-43

51-47

Mannite
Meconic acid .

c'gH^Og1
C7H4O7

39-56
42-0

7-69
2-0

52-75
56-0

Meconin . . .

C10H1004

61-85

5-15

33-00

262 PERCENTAGE .COMPOSITION OF CONSTITUENTS.

NAME.

FOEMULA.

C.

H.

O.

N.

S.

Melanthin

Co H. O

62-4

9-0

28-6

Melezitose

CUELjOu

42-10

6-43

51-47

Melissyl alcohol

C30H690

82-19

14-15

3-66

Melitose

C oHooOn

42-10

6-43

51-47

Menispermine

C18H24N2O2

72-00

8-00

10-65

9-35

Menthol

C10H20O

76-93

12-82

10-25

Menyanthin .

C22H36On

55-46

7-56

36-98

Metarabic acid

^i2-*-l22On

42-10

6-43

51-47

Methyl alcohol

r^TT n

OJtL4U

37-50

12-50

50-00

Methylamine

CH5N

38-71

16-13

45-17

Methylconiine

C9H17N

77-69

12-23

10-07

Methysticin .

65-85

5-64

28:51

Milk-sugar

C19H2oOn

42-10

6-43

51-47

Mongumic acid
Morphine

C17H19°N63

66-0
71-58

4-6
6-67

29-3
16-84

4-91

Morin ....

A TT r\

15~^10 7

59-61

3-31

37-08

Moschatine .

C21H27N07

68-22

6-66

27-65

3-45

Mucedin

9

54-11

6-90

21-48

16-63

0-88

Muscarine

CsH^NO,

50-42

10-92

26-89

11-77

Mycose ....

42-10

6-43

51-47

Myristic acid .

Ci"4IL)8Oo

73-68

12-28

14-04

Myron ic acid .

CioHinNSoOio

31-83

5-04

42-42

372

16-99

Narceine

Co H9 NO

59-63

6-28

31-09

3-02

Narcotine

C~2H93NO7

63-92

5-57

27-12

3-39

Naringin

C^HogOjg

55-6

5-6

38-8

Natalo'in
Nepaline

Cl6H19O7 (?)

C36H49NO]2

59-44
63-09

5-88
7-47

34-68
27-32

2-12

Nicotine

C10H14N2

74-08

8-64

17-28

Nucite ....

C6H1206

40-00

6-66

53;33

Oak-bark tannic acid

53-85

5-13

41-02

Oenanthic acid

C27H^026

64-12

11-44

24-44

Oleic acid .

76-59

12-06

11-35

Ononin

CTT f\ "
SO "^34 13

59-80

5-64

34-56

Orcin ....

C7H802

6776

6-45

25-81

Orsellic acid .

C8H804

57-15

4-76

38-09

Ostruthiin
Oxalic acid

CTT f~\ /O\
14J±17U2 (>)

C9H.,04

77-07
26-66

7-95
2-22

14-98
71-11

Oxyacan thine
Pseoniofluorescin .

C32H46N20H
C12H1002, H20

60-57
71-38

7-26
5-89

27-76
24-73

4-42

Palmitic acid
Papaverine .

C°H^N04

75-00
70-79

12-50
6-20

12-50

18-88

4-13

Pararabin

C^HooOn

42-10

6-43

51-47

Parellic acid .

C9H604

60-67

3-37

35-96

Paracoto'in
Paricine . . .

C19H1206
C^N.0

67-85
75-59

3-57
7-09

28-58
6-29

11-02

Paridin ....

57-83

8-43

33-74

Parillin ....

C14H94O2

60-4

9-0

30-6

Paytine.
Peucedanin .
Philyrin

C21Ho0N2O

C* TT (~\

C^H^O,!

7974
70-58
60-67

6-33

5-88
6-37

5-06
23-54
32-96

8-86

Phlorizin .

C21H24OIO

56-15

5-81

38-04

Phloroglucin .

C6H603

57-13

4-76

38-11

Physalin

C14H]605

63-64

6-06

30-30

Physostigmine

C15H21N302

65-49

7-64

11-60

15-27

Phytosterin .

C26H440

83-87

11-83

4-30

Picropodophyllin .
Picroroccelline

6771
68-08

5-88
6-31

26-41
17-05

8-56

Picrotoxin

C12H14655

60-50

5-88

33-62

PERCENTAGE COMPOSITION OF CONSTITUENTS. 263

NAME.

FORMULA.

C.

H.

O.

N.

S.

Pilocarpine .

C23H34N404

64-18

7-91

14-89

13-02

Pimaric acid .

O TT O

79-47

9-93

10-59

Pinipicrin

C^H-jgOj!

55-46

7-56

36-98

Pinite ....

C6~H12O5

43-9

7-2

48-9

Piperine

C17H]9N03

71-58

6-67

16-84

4-91

Pipitzaho'ic acid

C15H20O3

72-58

8-06

19-36

Populin ....

CooHogO10

56-34

6-10

37-56

Propionic acid

C3H602

48-65

8-11

43-24

Propyl alcohol ,
Protocatechuic acid

C3H80
C7H604

60-00
54-54

13-33
3-90

26-66
41-56

Purpurin

C14H805

65-62

3-13

31-25

Pyrocatechin .

C6H602

65-45

5-16

29-09

Pyrogallic acid

C6H603

57-13

4-76

38-11

Quassin ....

C10H12O3

66-67

6-67

27-66

Quercetin

59-21

3-95

36-84

Quercite

Cg^Hjo'Og

43-9

7-2

4 $-9

Quercitrin

Cj^H14O8

55-90

4-35

.£•75

Quinamine

C19Ho4N2O2

73-08

7-69

10-25

8-98

Quinine and Quinidine .

C20H94N202

75-02

6-66

10-43

8-64

Racemic acid . .

C4H606

32-0

4-0

64-0

Rhatania-red .

62-17

4-81

33-02

Rhatania tannic acid

Co Hr, O9

59-40

4-95

35-65

Resorcin

c H'OO

65-45

5-16

29-09

Rhinacanthin

Cj4Hj804 (?)

67-20

7-20

25-40

Rhceadine

C21H21N06

6579

5-48

25-08

3-65

Ricinoleic acid

C 8H34O3

72-48

11-41

16-11

Roccellic acid

C17Ho2O4

68-00

10-66

21-34

Rottlerin

Co H O

71-00

10-05

18-95

Ruberythric acid

C526H6oO31

54-64

5-04

40-32

Rubian .

CTT f\ /OS
se-^-es^ao \:)

55-08

5-57

39-35

Rubichloric acid

CTT r» /o\
14-tl16^'9 (')

51-22

4-88

43-90

Sabadilline .
Sabatrine

C41H66N2013 (?)
C51H86N2017

61-29
61-69

8-85
8-78

26-40
2676

3-46

2-77

Salicin .

54-54

6-29

39-17

Salicylic acid .

C7H603

60-87

4-42

34-78

Salicylous acid
Sanguinarine .

C19H17N04

68-85
70-59

4-92
5-26

26-23
19-82

4-33

Santalin .

CicHi.Ojc (?)

65-69

5-11

29-20

Santonin

4&A

73-17

7-32

19-51

Saponin .

C52H86026 (?)

55-4

7-6

36-9

Scleromucin .

29-67

6-44

9

6-41

(26-8

ash)

Scleroxanthin

C10H1004

61-8

5-1

32-0

Sclerotic acid .

40-0

5-2

50-6

4-2

Scoparin

CTT /"V /0\
OlJn.o2Wg \i)

58-06

5-06

36-87

Sinalbin

C30H44N2So018

47-87

5-85

34-05

372

8'51

Sulphocyanide of sinapine
Sinistrin

C17HgN2S05

55-43
44-44

6-53
6-17

21-74
49-39

7-61

8-69

Socalo'in
Solanine

OjXX
C42H87N015

59-63
60-66

5-59
8-78

34-78

28-88

1-68

Sorbin .

C6H12O6

40-00

6-66

53-34

Sparteine

78-05

10-57

11-38

Staphisagrine .

C20H32NO5

67-5

8-4

20 '-5

3-6

Starch .

Q Jj" Q

44-44

6-17

49-39

Stearic acid .

C H. CX>

76-06

12-68

11-26

Strychnine

C21Ho2N262

77-24

6-54

7-30

8-92

Styracin

C]SH1602

81-82

6-06

12-12

Styrol .

92-31

7-69

264 PERCENTAGE COMPOSITION OF CONSTITUENTS.

NAME.

FOEMULA.

C.

H.

O.

N.

S.

Succinic acid .

C4H604

40-68

5-09

54-23

Syringin

54-81

6-73

38-46

Tannaspidic acid .

C26H28On

60-46

5-42

34-12

Tannin .

CTT f\
27-C122V^17

52-42

3-56

44-02

Tartaric acid .

32-0

4-0

64-0

Terpene.
Thebame

and C20H32
C19H21N03

88-23
73-31

11-77
6-75

15-44

4-50

Theobromine .

C7H8N4O0

46-67

4-44

17-78

31-11

Thevetin

r TT n "

<-'54±184U24

58-06

7-53

34-41

Thujin . . .
Thymol ....

c2x4o2

52-86
80-00

4-84
9-33

42-30
10-77

Trimethylamine

C3H9N

61-02

15-25

23-73

Triticin ....

C12H22On

42-10

6-43

51-47

Turpethin
Tyrosin ....
Umbelliferon .

C^H^gOjg

C9HnN08
C9H603

56-66
59-66
66-66

777
6-07
3-71

35-57
26-54
29-63

773

Usnic acid

C18H1808

59-39

4-94

35-36

Valerianic acid

58-82

9-80

31-37

Vanillin

C8H8O3

63-13

5-26

31-58

Veratrine

C52H86N2015(?)

64-42

8-70

23-97

2-91

Veratro'idine .

C24H37N07 (?)

63-8

8-2

24-9

3-1

Vitellin (Brazil nut)

52-29

7'24

21-06

18-09

1-32

Vulpic acid .

C17H14O5

70-81

4-35

24-84

Xanthorhamnin

51-08

5-83

43-09

265

COMPOSITION OF THE MORE IMPORTANT CONSTITU-
ENTS OF PLANTS, ARRANGED ACCORDING TO
PERCENTAGE OF CARBON.

c.

H.

O.

N.

S.

NAME.

26-66

2-22

71-11

Oxalic acid.

31-58

5-26

63-16

Glycolic acid.

31-81

5-04

42-42

372

16-99

Myronic acid.

32-00

4-00

64-00

...

Tartaric and racemic acid.

35-82

4-48

5970

Malic acid.

36-36

6-06

36-37

21-21

...

Asparagine.

37-50

417

58-33

...

Citric acid.

37-50

12-50

50-00

...

Methylic alcohol.

38-71

16-13

45-17

Methylamine.

39-13

870

5217

...

Glycerin.

39-34

8-20

52-46

...

Erythrite.

39-56

7-69

52-75

Dulcite, isodulcite, mannite,

etc.

40-00

6-66

53-33

Acetic and lactic acid, glu-

cose, etc.

40-00

5-2

50-6

4-2

Sclerotic acid.

40-68

5-09

54-23

Succinic acid.

41-38

3-45

55-17

Aconitic acid.

41-38

3-45

5517

Fumaric and male'ic acid.

42-0

2-0

56-0

Meconic acid.

42-10

6-43

51-47

Arabic and metarabic acid,

pararabin, triticin, saccha-

rose, etc.

43-75

6-30

50-19

Kinic acid.

43-9

7-2

48-9

Finite and quercite.

44-21

5-26

50-53

...

Boheic acid,

44-44

9-63

35-55

10-37

Betaine.

44-44

3-70

51-85

Hydrocyanic acid.

44-44

4-76

51-80

Cyclopin.

44-44

6-17

49-39

Cellulose, dextrin, inulin,

levulin, sinistrin, starch.

44-84

5-33

49-83

tt

Cinchona-tannic acid.

45-65

2-17

52-24

Chelidoiiic acid.

46-67

4-44

17-78

3i:ii

Theobromine.

47-87

5-85

34-05

3-72

8:51

Sinalbine.

48-65

8-11

43-24

Propionic acid.

49-48

5-15

16-51-

28-86

...

Caffeine.

49-59

12-39

26-44

11-57

...

Choline.

49-60

4-92

43-26

2-22

Indican.

50-24

6-81

2413

18-37

6:45

Conglutin.

50-42

10-92

26-89

11-77

Muscarine.

51-0

67

25-4

16-1

6:8

Glutencase'in.

51-00

7-00

42-00

...

Ericolin.

51-02

4-89

44-87

...

...

Fraxin.

51-22

4-88

43-90

Rubichloric acid.

51-47

7-02

24-29

16:82

6:40

Legumin.

52-01

5-88

42-11

Cinchona-tannic acid.

52-07

7-24

21-06

18:09

1:32

Vitellin.

266 COMPOSITION OF IMPORTANT CONSTITUENTS.

c.

H.

0.

N.

S.

NAME.

52-39

4-78

42-83

Daphnin.

52-42

3-56

44-02

Gallotannic acid.

52-45

6-81

22-21

15:65

6'-8

Albumin.

52-47

5-79

40-23

1-53

...

Laurocerasin.

52-51

5-91

38-52

3-06

Amygdalin.

52-53

7'38

40-27

...

...

Helleborein.

52-60

7-00

21-49

18:06

6'-85

Gliadin.

52-86

4-84

42-30

Thujin.

52-9

5-2

41-9

Apiin.

53-21

7-60

39-19

...

Digitonin.

53-33

5-19

41-48

Cinchona-red.

537

6-1

40-2

Arbutin.

53-85

5-13

41-02

Oak -bark tannic acid.

53-91

8-59

37-50

...

Convallamarin.

54-08

4-72

41-20

Datiscin.

54-11

6-90

21-48

16:63

6:88

Mucedin.

54-54

3-90

41-56

Protocatechuic acid.

54-55

9-09

36-36

...

Butyric acid.

54-54

6-29

39-17

...

...

Salicin.

54-63

5-47

39-90

...

Lupinin.

54-64

5-04

40-32

...

Kuberythric acid.

54-77

5-39

39-84

Hesperidin.

54-81

6-73

38-46

...

...

Syringin.

54-87

7-37

37-50

Convolvulin.

54-96

9-92

24-43

10:69

Leucine.

55-08

5-57

39-35

Rubian.

55-29

7-83

36-87

...

Cyclamin.

55-4

7-6

36-9

Saponin.

55-43

6-53

21-74

7:61

8:69

Sulphocyanate of sinapine.

55-46

7-56

36-98

...

...

Menyanthin.

55-46

7-56

36-98

Pinipicrin.

55-6

5-6

38-8

...

...

Naringin.

55-81

6-99

37-20

...

Crotonic acid.

55-63

1-99

42-38

...

...

Ellagic acid.

55-90

4-35

39-75

...

Quercitrin.

56-14

6-43

37-43

Coniferin,

56-15

5-81

38-05

Phlorizin.

56-25

3-75

40-00

Maclurin.

56-34

6-10

37-56

Populin.

56-37

6-04

37-59

Ipecacuanha-tannic acid.

56-66
5675

7-77
5-41

35-57
37-84

...

Jalapin and turpethin.
Caffeo-tannic acid.

56-75

5-40

37-85

Carthamin.

57-13

4-76

38-11

.. .

Phloroglucin, pyrogallol, etc.

5715

4-76

38-09

M

Orsellic acid.

57-32

7-01

35-67

Globularin.

57-57

5-12

34-96

i'-50

6:85

Cathartic acid.

57-64

7-42

34-94

Dulcamarin.

57-69

13-46

15-38

13:46

Amanitine.

58-00

5-06

36-87

...

Scoparin.

58-06

7-53

34-41

...

Thevetin.

58-22

5-50

36-28

...

Curacao-aloin.

58-23

4-64

37-13

Chrysorhamnin.

58-24

7-38

34-38

...

Ca'incin.

58-82

9-80

31-37

Valerianic acid.

59-21

3-91

36-84

...

Quercetin,

59-26

6-17

34-57

...

Capaloin.

COMPOSITION OF IMPORTANT CONSTITUENTS. 267

c.

H.

O.

N.

S.

NAME.

59-34

5-49

35-17

Everninic acid.

59-44

5-88

34-68

Nataloin.

59-40

4-95

35-65

Rhatania-tannic acid.

59-39

4-94

35-36

Usnic acid.

59-63

5-59

3478

Socaloin.

59-63

6-28

31-09

3:02

...

Narceine.

59-66

6-07

26-54

7-73

...

Tyrosine.

5978

7-47

32-75

Colocynthin.

59-80

5-64

34-56

...

Ononin.

59-92

7-05

32-66

117

...

Glycyrrhizic acid.

59-95

8-05

32-00

Digitalin.

60-00

8-00

32-00

...

...

Angelic acid.

60-00

8-33

31-67

...

Bryonin.

60-00

4-44

35-56

...

Cetraric acid.

60-00

13-33

26-67

...

...

Propylic alcohol.

60-37

4-40

35-23

...

Lecanoric acid.

60-40

9-0

30-6

Parillin.

60-46

5-42

34-12

...

...

Tannaspidic acid.

60-50

5-88

33-62

...

Picro toxin.

60-53

6-82

28-50

415

...

Colchicine.

60-57

7-26

27-76

4-42

...

Oxyacanthine.

60-66

8-78

28-88

1-68

...

Solanine.

60-67

3-37

35-96

Parellic acid.

60-67

6-37

32-96

...

...

Philyrin.

60-71

5-95

33-34

...

Barbaloin.

60-81

4-90

34-29

...

Gyrophoric acid.

60-85

4-75

34-40

...

Gardenin.

60-86

4-42

34-78

...

Salicylic acid.

60-90

4-81

34-23

...

Catechin.

61-02

15-25

2373

Trimethylamine.

61-03

8-56

25-27

514

Jervine.

61-29

8-85

26-40

3-46

Sabadilline.

61-39

6-67

29-77

217

Aconitine.

61-44

4-82

33-74

...

Evernic acid.

61-69

8-78

26-76

277

...

Sabatrine.

61-8

51

32-0

...

Scleroxanthin.

61-85

5-15

33-00

Meconin.

61-86

5-15

32-99

Benzohelicin.

62-01

515

33-64

...

Cinchona-no va-red.

62-07

10-35

27-58

...

Caproic acid.

62-07

3-45

34-48

fm

Luteolin.

62-17

8-81

29-02

Gratiolin.

62-17

4-81

33-02

...

Rhatania-red.

62-33

6-49

31-17

Crocin.

62-4

9-0

28-6

Melanthin.

62-46

4-66

32-88

Catechu-tannic acid.

62-50

4-17

33-33

...

Anemonin.

62-68

7-46

29-88

...

Antiarin.

62-92

4-72

32-36

Linin.

63-00

7-0

30-0

Cnicin.

63-09

7-47

27-32

212

Nepaline.

6313

5-26

30-58

...

...

Vanillin.

63-16

9-60

27-24

Convallarin.

63-44

6-58

25-20

4-38

...

Colchiceine.

63-57

4-63

31-79

Hsematoxylin.

63-60

8-50

27-90

...

Digi toxin.

63-64

6-06

30-30

...

Physalin.

268 COMPOSITION OF IMPORTANT CONSTITUENTS.

c.

H.

O.

N.

S.

NAME.

63-83

6-38

29-76

Coriamyrtin.

63-8

8-2

24-9

3-i

Veratroidine.

63-92

5-57

27-12

3-39

Narcotine.

64-12

11-44

24-44

...

Oenanthic acid.

64-20

6-17

29-63

Filicin.

64-23

8-77

27-00

Ceric acid.

64-42

870

23-97

2:91

Veratrine.

64-48

4-40

31-20

...

Kampferid.

64-55

8-66

23-47

3!42

Delphinine.

64-80

13-51

21-62

Butylic alcohol.

64-90

7-6

27-5

Cailcedrin.

65-11

3-87

31-02

...

Gentisin.

65-26

6-66

28-07

Kosin.

65-28

5-60

29-03

Columbin.

65-45

5-16

29-09

Pyrocatechin, hydroqui-

none, resorcin, etc.

65-49

7-64

11-60

15-27

Physostigmine.

65-62

3-13

31-25

Purpurin.

65-69

5-11

29-20

Santalin.

65-79

5-48

25-08

3:65

Rhoeadine.

65-85

5-64

28-51

Methysticin.

65-97

5-75

20-95

7!33

Chlorogenine.

66-0

4-6

29.3

Mongumic acid.

66-05

8-26

25-69

Laserpitin.

66-38

6-38

27-23

...

Limonin.

66-44

6-57

22-15

4-84

Cocaine.

66-66

9-63

23-71

Hederic acid

66-66

3-71

29-63

...

Umbelliferon.

66-67

6-67

26-66

...

Quassiin.

66-67

3-70

30-63

...

Emodin.

66-98

6-98

26-04

Athamanthin.

67-00

9-64

16-30

7:io

Gelsemine.

67-11

5-43

27-46

Brasillin.

6712

11-89

11-19

9:79

Conhydrine.

67-20

7-20

25-40

Rhmacanthin.

67-41

5-62

29-96

...

Cubebin.

67-41

5-62

29-96

...

Curcumin.

67-5

8-4

20-5

3-6

Staphisagrine.

67-6

4-2

28-2

...

Frangulic acid.

67-71

5-88

26-41

...

Picropodophyllin.

67-76

6-45

25-81

...

Orcin.

67-85

3-57

28-58

...

Paracoto'in.

68-06

5-08

14-32

12:34

Chelidonine.

68-07
68-08

5-04
6-31

26-89
17-05

8:56

...

Erythrocentaurin.
Picroroccelline.

68-22

6-66

27-65

3-45

Moschatine.

68-39

777

16-58

7-25

Ditaine.

68-85

4-92

26-23

Salicylous and benzoic acid.

68-96

8-04

23-00

...

Elaterin.

69-56

7-24

23-20

...

Betaorcin.

69-72

5-42

24-86

Alkannin.

69-76

11-62

18-61

...

Capric acid.

69-84

4-76

25-39

...

Coto'in.

70-00

9-29

20-71

...

Capsaicin.

70-05

. 6-59

16-25

711

Cusconine and aricine.

70-38

8-50

21-12

...

Absinthiin.

70-58

7-95

16-60

4:84

Atropine, hyoscyamine, etc.

COMPOSITION OF IMPORTANT CONSTITUENTS. 269

c.

H.

0.

N.

S.

NAME.

70-58

5-88

23-54

...

Peucedanin.

70-59

5-26

19-82

4:33

...

Sanguinarine.

70-79

6-20

18-88

4-13

...

Papaverine.

70-81

4-35

24-84

...

Chrysopicrin (vulpic acid).

70-87

7-87

1575

5:51

...

Atherospermine.

70-87

3-94

25-19

...

Chrysophanic acid.

70-9

9-5

15-6

3!9

...

Delphinoidine.

71-00

10-05

18-95

...

Rottlerin.

71-38

5-89

2273

...

Pseoniofluorescin .

71-58

6-67

16-84

4:91

...

Morphine and piperine.

71-64

5-08

19-10

4-18

Berberine.

72-00

8-00

10-65

9-35

...

Menispermine (?)

72-09

12-04

15-87

Laurostearic acid.

72-24

7-02

16-06

4-68

...

Codeine.

72-31

5-22

22-47

Chrysarobin.

72-41

1379

1379

...

...

Heptyl-alcohol.

72-48

11-41

16-11

...

Ricinoleic acid.

72-58

8-06

19-36

...

...

Pipitzahoic acid.

72-90

6-54

7-48

13-08

...

Harmaline.

72-92

5-41

21-62

Cinnamic acid.

73-03

7-69

10-25

8:98

...

Quinamine.

73-17

7-32

19-32

Santonin, eugenol, eugenin.

73-28

3-82

12-22

10-68

...

Indigo-blue.

73-31

675

15-44

4-50

...

Berberine and theba'ine.

73-58

5-67

7-54

13-21

Harmine.

73-62

11-66

14-72

...

Bryoidin.

73-84

13-84

12-32

Caprylic alcohol.

73-85

8-31

4-92

12-92

...

Cytisine.

73-68

12-28

14-04

Myristic acid.

73-97

4-11

21-92

...

Coumarin.

74-08

8-62

17-28

Nicotine.

74-4

97

9:57

5-62

1-37(P)

Chlorophyllan.

74-54

10-56

14-90

...

Asclepin.

74-57

8-48

9-04

7:81

Aspidospermine.

74-6

5-3

21-1

Gronhartin.

74-66

7-55

17-78

Bixin.

75-00

3-57

21-44

...

...

Alizarin.

75-00

12-50

12-50

Palmitic acid.

75-02

6-66

10-43

8-64

...

Quinine and quinidine.

75-04

9-07

15-89

Anacardic acid.

75-59

7-09

6-29

11:02

...

Paricine.

75-78

7-37

16-85

Helleborin.

76-06

12-68

11-26

...

...

Stearic acid.

76-59

12-06

11-35

Oleic acid.

76-81

12-00

11-20

...

Coniine.

76-83

8-53

14:64

Helenin.

76-92

12-82

10-26

...

Arachic acid, menthol,

capric aldehyde.

77-07

7-95

14-98

Ostruthiin.

77-24

6-54

7-30

8:92

Strychnine.

77-55

7-48

5-44

9-53

Cinchonine and cinch oni-

dine.

77-69

12-23

10-07

Methylconiine.

77-92

11-69

10:39

...

Borneol.

78-05

10-57

...

11:38

Sparteine.

78-3

11-2

v

9

Conessine.

78-43

5-68

15!89

...

Aribine.

270 COMPOSITION OF IMPORTANT CONSTITUENTS.

c.

H.

0.

N.

S.

NAME.

78-57

9-52

11-91

Abietic acid.

78-68

13-95

7-37

...

Cetyl-alcohol.

78-94

10-53

10-53

...

Camphor and caryophyllin.

79-02

13-17

7-81

...

Cerotic acid.

79-24

5-65

15-11

...

...

Benzaldehyde.

79-47

9-93

10-59

Pimaric acid.

79-74

6-33

5-06

8:86

Paytine.

80-00

9-33

10-77

...

Thymol and carvol.

80-25

9-55

10-20

Cardol.

80-67

5-88

13-45

Cinname'in.

81-08

8-11

10-81

...

Anethol.

81-51

13-21

5:28

...

Curarine.

81-81

14-14

4-05

Cerotyl-alcohol.

81-82

6-06

12-12

...

Styracin and cinnamic

aldehyde.

81-82

11-04

714

Euphorbone and lactucerin.

82-19

14-15

3-66

Melissyl alcohol.

82-44

11-41

6-15

...

Hydrocarotin.

82-57

11-36

6-06

Betulin.

83-49

11-79

4-73

...

Amyrin.

83-87

11-83

4-30

...

Phytosterin.

84-11

12-15

3-74

...

...

Cholesterin.

84-37

9-37

6-26

Carotin.

88-24

11-76

...

Caoutchouc, terpenes, etc.

92-31

7-69

...

...

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

arabic, 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-tanmc, 161

cambogic, 135

capric, 13, 119

caproic, 13, 119

caprylic, 13, 119

carbusnic, 150

catechuic, 41, 44, 156

„ estimation, 157

catechu-tannic, 156

cathartic, 86, 248

cathartogenic, 248

celastrus-tannic, 163

cetraric, 151

chelidonic, 148

chrysophanic, 36, 132

cinchona-no va-tannic, 163

cinchona-tannic, 162

cincho-tannic, 162

cinnamic, 25

citric, 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 tannic, 162
frangulic, 133
fumaric, 70, 232
gallic, 32, 133, 226

„ detection and estimation,

47, 137
gallo-tannic, 160, 226

„ estimation, 159

gelsemic, 205
glutamic, 207
glycolic, 233
glycyrrhizic, 171
gummic, 210
gyrophoric, 150
helianthic, 170
hydrocarbusnic, 151
hydrocyanic, 24, 29
isobutyric, 119
jalapic, 140
jervic, 148
kinic, 232
lactic, 232
lauric, 13, 112
lecanoric, 149, 151
leditannic, 163
lichenostearic, 151
linoleic, 11

„ estimation, 111
lobaric, 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
methylcrotonic, 13, 119
fciethylsalicylic, 30

272

INDEX.

Acid, mongTimic, 127
morintannic, 158
myristic, 15, 16, 112
myronic, 165
nitric, 78

,, estimation, 83, 84, 85
nucitannic, 163
octylic, see caprylic
cenanthic, 119
oleic, 11, 112, 113

„ detection, 18

„ estimation, 111
ophelic, 147
orsellic, 149
oxalic, 70, 91, 230
oxyusnetinic, 150
palmitic, 18, 112
para-oxybenzoic, 35, 36
parellic, 150
patellaric, 150
pectic, 211
pelargonic, 13
phosphomolybdic, 56
phosphoric, 226, 229
phyllic, 127
picric, 56
pimaric, 127
pinic, 127
pipitzahoic, 136
podocarpic, 127
podophyllic, 139
polygonic, 149
polyporic, 90
propionic, 119
protocatechuic, 35
pteritannic, 163
quercitannic, 161
quinic, see kinic
quinovic, 175
• racemic, 70, 229
rhatania-tannic, 157
ricinoleic, 19
roccellic, 149
ruberythric, 134
rubichloric, 232
rufigallic, 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

„ estimation, 228

Acid, toxicodendric, 24

trimethylacetic, 119

usnic, 150, 152

valerianic, 13, 24, 35, 119

viridic, 161

vulpic, 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
,, separation 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, sulphocyanate 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.

273

Alcohol, octyl, 30

Alcohols, boiling points of, 30

Alcohols, primary, secondary, etc., 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

Alizarin, 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 aqueous solution,49
group-reagents for, 55
isolation of, 55
microsublimation of, 181
not separated by shaking, 57
of cinchona, 198

„ rarer, 198

,, 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

Ammonia, examination for, 78

Amygdalin, 164

Amylin, 253

Amylodextrin, 250

Amylum, see starch.

Amyrin, 109

Analysis, general method, 5

Anemonin, 109

Anemonol, 109

Angelicin, 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
Aphrodsescin, 170
Apiin, 170
Apricots, oil of, 102
Arabin, 210
Arabinose, 218
Arbutin, 167
Argyraescin, 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
Betaorcin, 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

INDEX.

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
Calif ornin, 175
Calycin, 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
Chamaelirin, 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

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
Chrysopicrin, 150
Chrysorhamnin, 135
Chylariose, 218
Cicutin, 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
Cnicin, 176

Cnicus benedictus, bitter principle of, 49
Cocaine, 203
Codeine, 50
Colchiceine, 49
Colchicine, 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
Cratsegin, 175
Crocetin, 171
Crocin, 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
Cyclopiafluorescin, 163
Cyclopia-red, 163
Cyclopin, 163
Cynanchocerin, 108
Cytisine, 203

Daphnin, 49, 168

Datiscin, 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

Dulcite, 225

Ecboline, 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
Erythrophlceine, 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, 31

Etiolin, 116
Ethylamine, 244
Eucalyn, 219
Eupatorin, 147
Euphorbon, 108

Fat-acids, fixed, 14

fractional precipitation 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
Filicin, 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

oleic 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

polarization of, 221
Glucoses, detection and estimation,
64,72

extracted by alcohol, 38, 48

various, 256
Glucosides, detection of, 53

direct examination for, 50

extraction of by ether, 33

extraction of from aqueous solu-
tion, 49

group-reagents for, 54

solubility of, 164
Glutamine, 82

detection of, 207

estimation of, 207
Gluten, 243
Glutencasein, 235
Gluten fibrin, 241, 242
Glutin, 241
Glycerides, 11
Glycerin, estimation of, 109
Glycyrrhizin, 171
Goa-powder, 132

Gold, chloride of, as alkaloid reagent, 56
Granulose, 249
Grape-sugar, see glucose
Gratiolin, 49, 172
Gronhartin, 136
Ground nut, oil of, 102
Guacin, 147
Guarana, 186
Guaranine, 186
Gum, 208

Gum arabic, varieties of, 211
Gum, see also ' Mucilage '
Gummicose, 210
Gum-resins, commercial, 1 29
Gypsophila struthium, saponin in, 69

Haemaloxylin, 32, 33, 136
Harmaline, 203
Harmine, 203
Hazel nut, oil of, 102
Helenin, 108
Helianthus, oil of, 102
Helleborein, 49, 172
Helleborin, 172
Hemp, oil of, 102
Hesperidin, 171
Hesperidin-sugar, 225
Homofluorescin, 151
Hop-bitter, 147
Hop-resin, 49
Hop, tannin of, 156
Horse chestnut, tannin of, 158
Humus, 90
Hurin, 148
Hydrastine, 205
Hydrocellulose, 250

Hydrocarotin, 109
Hydrocotoin, 147
Hygrine, 203
Hyoscine, 60
Hyoscyamine, 50

estimation of, 60, 183
Hypochlorin, 114, 116

Incrusting substance, 95, 253
Indican, 174
Tndigo blue, 174
Indiglucin, 174
Indigo white, 174
Inosite, 219
Introduction, 1
Inulin, characters, 87

detection of, 66

estimation and extraction of, 86

examination for, 86
Inuloid, 87
Invertin, 237
Invert sugar, 218
Ipecacuanha, tannin of, 163
Isodulcite, 225
Isophlorrhizin, 169

Jalapin, 140
Jalapinol, 140
Jervine, 180
Juniperin, 148
Jurubebine, 205

Kampferid, 108
Kawain, 148

Knoppern-galls, tannin of, 159
Kosin, 107

Lactose, 210

Lactucerin, 108

Lactucin, 176

Lactucon, 108

Laserol, 145

Laserpitin, 145

Laurocerasin, 164

Legumin, estimation of, 79, 234

Leucine, 207

estimation of, 207
Leucotin, 147 .
Levulin, 212

alcoholate, 213

detection and estimation of, 67,

213

Levulosan, 220
Levulose, 218
Lichen-acids, test for, 151
Lichenin, 249, 251
Lichens, microscopical examination of,

151

Lichen-starch, 251
Lignin, 95, 252, 253

INDEX.

277

Lignin, micro-chemical characters of,

255
Lignin, micro-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
Lycine, 205
Lycopin, 148
Lycopodine, 205

Maclurin, 158

Maltose, 221

Mangostin, 148

Mannite, 77, 224

Marattin, 70

Marnibin, 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
Methysticin, 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

modified method of examination,
209

vegetable, 208
Mudarin, 176
Munjestin, 135
Murray in, 171
Muscarine, 205

Mustard, volatile oil of, 166

Mycose, 221

Myosin, 235

separation from vitellin, 236

Myrica cerifera, wax from, 110
quercifolia, ,, „ 110
species, ,, „ 110

Myrobalans, tannin of, 156, 160

My rosin, 165

Myroxocarpin, 108

Narceine, 49, 50
Narcotine, 50

estimation of, 61, 184, 199
Naringin, 171
Narthecin, 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
Nucin, 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
Oleandrine, 205
Olivil, 176
Ononin, 170

Operations, preliminary, 5
Opium, estimation of alkaloid in, 199
Orcin, estimation of, 152
Oreoselon, 145
Ostruthiin, 144
Oxyacanthine, 205

278

INDEX.

Oxyaloin, 178
Oxycyclopin, 163
Oxyleucotin, 147
Oxyneurin, 205

Pseoniofluorescin, 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
Phseoretin, 132
Phaseomannite, 219
Philygenin, 169
Philyrin, 169

Phlobaphene, 88, 90

Phloroglucin, 35

Phlorose, 218

Phlorretin, 169

Phlorrhizin, 169

Phyllocyanin, 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

Pinipicrin, 167

Finite, 225

Piperine, 49

estimation of, 188

Pittosporin, 170

Platinum, perchloride of, as alkaloid
reagent, 56

Plumbagin, 149

Podophyllotoxin, 139

Podophyllum peltatum, 139

Polychroite, 171

Pomegranate, tannin of, 160

Poppyseed, oil of, 102

Populin, 49, 168

Porphyrine, 203

Potassiobismuthic iodide, as alkaloid
reagent, 55

Potassiocadmic 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

Punicine, 205

Purpurin, 133

Pyrocatechin, 32, 33, 36, 138

Pyrogallol, 35, 36, 137

Quassiin, 49, 149

Quebrachin, 49

Quercetin, 36, 138

Quercin, 176

Quercite, 225

Quercitrin, 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
oxidation -products of, 34
purification, 34

Resorcin, 35

Rhamnin, 135

Rhamnodulcite, 225

Rhatany-red, 157

Rhatany-root, tannin of, 157

Rhinacanthin, 135

Rhinacanthus communis, 135

Rhinanthin, 163

Rhinanthogenin, 163

Rhoeadine, 203

Rhoeaginine, 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, Bottger's test for, 76

characters of, 76

estimation of, 75

examination for, 65, 72

inversion of, 75
Saccharoses, 220
Salicin, 33, 50, 168
Salicin-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

Sinalbin, 166

Sinapine, acid sulphate of, 166

sulphocyanate of, 166
Sinistrin, 212

alcoholate of, 213

detection and estimation, 67, 213
Sinkaline, 205
Smilacin, 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

Tampicin, 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
„ 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

INDEX.

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
Trhnethylamine, 245
Trimethylaniline, 50
Triticin, 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

Veratrine, 50

estimation of, 61, 184
Veratroidine, 179, 189
Viola tricolor, 139
Violaquercitrin, 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.

LONDON : BAILLIERE, TINDALL, AND COX, KING WILLIAM STREET.