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Full text of "Treatise on general and industrial organic chemistry"

TREATISE ON 
GENERAL AND INDUSTRIAL 

ORGANIC CHEMISTRY 



ALSO BY DR. MOLINARI 
TREATISE ON 

GENERAL AND INDUSTRIAL 
INORGANIC CHEMISTRY 

TRANSLATED BY 

DR. ERNEST FEILMANN 

B.Sc., Ph.D., F.I.C. 
With 280 Text-Figures and 3 Plates 



TREATISE ON 

GENERAL AND INDUSTRIAL 

ORGANIC CHEMISTRY 



BY 

DR. ETTORE MOLINARI 

Professor of Industrial Chemistry to the Society for the 

Encouragement of Arts and Manufactures and 

of Merceology at the Luigi Bocconi 

Commercial University, Milan 



TRANSLATED FROM THE SECOND ENLARGED AND REVISED 
ITALIAN EDITION BY 

THOMAS H. POPE 
B.Sc., A.C.G.I., F.I.C. 

School of Malting and Brewing, 
University of Birmingham 



WITH 506 ILLUSTRATIONS 



PHILADELPHIA 
P. BLAKISTON'S SON & CO. 

1012 WALNUT STREET 
1913 



T P I 



Ml**. MM O 




Printed in Great Britain 



' * 

. .* - 

-> 



TRANSLATOR S PREFACE 

FOR the purposes of this English translation of his " Trattata di Chimica 
Organica," the author has made a number of alterations in and additions to 
the text of the second Italian edition, these consisting principally in ampli- 
fications of the statistical data referring to Great Britain and the United 
States. 

It has been deemed undesirable to convert the metric weights and measures 
into those of the English system, but, in general, prices are given in British 
currency, twenty-five lire being taken as the equivalent of one pound sterling. 
Where quantities are given in tons, the latter are to be read as metric tons of 
1000 kilograms or 2204' 6 Ib. avoirdupois. 

The abbreviations employed for the different units of weights and measures 
are those in common use, and temperatures are expressed in degrees Centigrade 
in all cases. 

THOMAS H. POPE 
BIRMINGHAM 



267544 



PREFACE TO THE SECOND ITALIAN 

EDITION 

THE first edition of this treatise on Organic Chemistry was published in 
two volumes in 1908 and 1909, and rapidly exhausted, the second edition 
being now published in one volume. The distribution of the matter is similar 
to that of the first edition, but many chapters have been brought up to date, 
others have been considerably amplified and others again have been introduced 
for the first time. The largest additions have been made in the chapters 
dealing with the treatment of tar, with colouring-matters, with alkaloids, &c. 

The statistics of production, exportation, and importation have been 
brought up to the year 1910 and, where possible, to 1911. Special attention 
has been devoted to this characteristic feature of the book, as experience has 
shown the author that among the most important factors in deciding the 
possibility or convenience of starting new or of extending existing industries 
are those governed by the laws of economics and statistics. 

The author will be grateful to any readers or colleagues who may point out 
omissions or errors, which are unavoidable in a work of this character with 
such varied contents in so condensed a form. 

This second edition is in course of translation into English and German. 



E. MOLINARI 
MILAN 



PREFACE TO THE FIRST ITALIAN 
EDITION 

A NEW treatise on Organic Chemistry might, in view of the existence of the 
excellent works of Bernthsen and Holleman, be considered superfluous. 

But both of these books, which differ little in the manner in which the 
subject is developed, are confined to a theoretical and systematic exposition 
of the many organic compounds, the industrial side of the question and the 
applications of these compounds being almost entirely neglected. It is hence 
difficult for the student to ascertain which of the thousands of substances 
described are really of practical importance. 

Modern teaching of chemistry adheres in a too one-sided manner to the 
old but fruitful idea of Liebig, that " to obtain a sound practical man it is 
necessary to train a good theorist." This conception was taken too literally, 
although it gave good results when chemical industry was in its infancy, 
since in those days any theorist could easily introduce new and important 
methods. But to-day, when the industry has attained the adult stage has 
advanced to such an extent and become so varied and complex, being stimulated 
incessantly by keen national and international competition, which demands 
rapid changes and improvements the valuable time of the young technician 
cannot be wasted in a protracted and sometimes sterile apprenticeship. Present- 
day conditions require, therefore, some such expansion of Liebig's maxim as the 
following : In order to produce, rapidly and with increased certainty, a sound, 
practical man, it is necessary to train a good theorist and to initiate him into 
both the theoretical and practical study of the more salient industrial problems. 

It does not suffice that the young chemist, about to begin his industrial 
or teaching career, should have a thorough knowledge, for instance, of the 
various syntheses and constitutional formulae of the sugars. He should also 
be acquainted with at least the general outlines of the industrial processes and 
of the technique of the manufacture of sugar, beginning with the slicing of the 
beets and proceeding to the exhaustion of the pulp, defecation, saturation, 
filtration with filter- presses, boiling, and vacuum concentration in multiple- 
effect apparatus, refining and centrifugation of sugar crystals, utilisation of 
residues, and so on. He should, indeed, understand the plant and chemical 
processes of the more important industries, as these often find application 
in the manufacture of products of a secondary or entirely new character. 

What would avail a study of the wonderful artificial colouring-matters 
derived from coal-tar, with the inexhaustible syntheses composing their theo- 
retical basis, if it were limited to a simple mnemonic exercise for the student 
and no notice were taken of the interesting practical applications to the dyeing 
of the various textile fibres ? 

Nor should the young student ignore statistics of production ; he should 
be able to appreciate the importance of variations in the exportation and 
importation of the principal chemical products, and to judge of the economic 
and social conditions with which such variations correspond. 

After a brief novitiate, he should be in a position to point out the more 
striking technical defects and the more marked difficulties met with in par- 
ticular industrial processes and to suggest rational and not fanciful remedies 



viii PREFACE 

It is this space, the vacant region representing a suitable fusion of theoretical 
with applied chemistry, which requires filling. This I have attempted in the 
present work, which of itself is certainly insufficient to cover the whole of the 
ground. 

The difficulties encountered in preparing the volume on Inorganic 
Chemistry are multiplied in dealing with Organic Chemistry, and this is the 
case not only as regards the collection and confirmation of the statistical 
data but of the chemical processes giving the best results in practice. For in 
any particular industry it has often been found that the results of investigations 
are in such disaccord with the practical data as to render it a matter of great 
uncertainty what conclusions should be presented to the reader. 

Inquiries addressed to manufacturers resulted in aggravation of this 
uncertainty, what was confirmed on the one hand being denied on the other, 
and plant guaranteed by one firm to be the best being decried by a competing 
firm. It hence became necessary to apply directly to the operatives working 
a given process and to draw conclusions from the whole of the data and 
information thus obtained. 

It is thus that readers may explain the contradictions between different 
authorities on one and the same subject, and also the fact that the conclusions 
reached by the author with reference to certain industrial processes are not 
always in accord with those given in other treatises. 

The intention has certainly not been to prepare a complete treatise on 
technological chemistry and still less on chemical technology. The work 
having to be restricted within limits of space approximating to those of vol. i, 
the author has descended to details only with some of the principal industries 
and especially with those best adapted to give a general idea of the different 
applications of chemical processes and of chemical technics. 

To this end the author has dwelt preferably on the industries of illuminating 
gas, sugar, alcohol, beer, acetic acid, dyeing, textile fibres, fats and soaps, 
explosives, &c. 

From these examples the student may gather much instruction applicable 
to many other industries not dealt with in detail. 

Repetition has been avoided and time and space saved by frequent references 
to arguments already developed in vol. i, " Inorganic Chemistry." 

Advice and collaboration are desired from readers and colleagues in order 
that gaps in the present work may be filled and inaccuracies and defects 
remedied. 

E. MOLINARI 

MILAN 



CONTENTS 
PART I. GENERAL 

PAOE 

PURIFICATION OF ORGANIC COMPOUNDS 2 

Crystallisation, 2 ; sublimation, boiling-point, fractional distillation, 2 ; 
rectification, 3 ; melting-point, 5 ; specific gravity, 6. 

ANALYSIS OF ORGANIC COMPOUNDS 6 

Qualitative composition, 6 ; quantitative estimation : of carbon and 
hydrogen, 7 ; of nitrogen, 10 ; of halogens, 11; of sulphur and phos- 
phorus, 12. 

CALCULATION OF EMPIRICAL FORMULA 12 

DETERMINATION OF MOLECULAR WEIGHT BY CHEMICAL MEANS 13 

POLYMERISM 14 

VALENCY OF CARBON, CONSTITUTIONAL FORMULA, ISOMERISM 14 

Theory of radicals and types, 14 ; structural formulae, 16 ; rational 
formulae, 17. 

METAMERISM, PSEUDOISOMERISM, TAUTOMERISM, DESMOTROPY 17 

STEREOISOMERISM OR SPACE ISOMERISM 18 

Stereoisomerism in derivatives with doubly linked carbon (alloisomerism), 
21 ; Stereoisomerism of nitrogen, 22 ; separation and transformation of 
stereoisomerides, 22. 

HOMOLOGY AND ISOLOGY 23 

PHYSICAL PROPERTIES OF ORGANIC COMPOUNDS IN RELATION TO 
THE CHEMICAL COMPOSITION AND CONSTITUTION 23 

Crystalline form, 24 ; solubility, 24 ; specific gravity, 24 ; molecular 

volume, 24 ; melting-point, 24 ; boiling-point, 24 ; heat of combustion and 

of formation, 25 ; heat of neutralisation, 25. Optical Properties : colour, 26 ; 

refraction, 26 ; influence on polarised light, 26 ; magnetic rotatory power, 27. 

Electrical conductivity, 27. 

CLASSIFICATION OF ORGANIC COMPOUNDS 28 

OFFICIAL NOMENCLATURE 28 



PART II. DERIVATIVES OF METHANE 

AA. HYDROCARBONS 

(a) SATURATED HYDROCARBONS 30 

Natural formation and general methods of preparation, 30 ; table of satu- 
rated hydrocarbons, 31 ; Methane, 32 ; properties, preparation, fire-damp, 
detonating mixtures, industrial preparation, 33-34 ; Ethane, 34 ; Propane, 
35 ; Butanes, 35 ; Pentanes, 35 ; Hexanes, 35 ; Higher Hydrocarbons, 36. 



x CONTENTS 

PA OK 

Illuminating Gas Industry : history, 36 ; components, 38 ; pro- 
perties, 38 ; retorts, 38 ; furnaces, 41 ; hydraulic main, 43 ; washing, 44 ; 
purification, 46 ; exhausters, 48 ; pressure regulators, 48 ; gasometers, 48 ; 
pressure regulators, 49 ; gas-meters, 50 ; yield, 51 ; statistics, 52 ; physical 
and chemical testing of illuminating gas, 53 ; comparison of different 
sources of light, 57 ; Oil Gas, 57. 

Petroleum Industry : localities of production, 58 ; hypotheses on the 
origin of petroleum, 59 ; composition and properties of crude petroleum, 62 ; 
industrial extraction and working of petroleum, 64 ; distillation, 66 ; chemical 
purification, 68 ; storage tanks, 69 ; statistics, 70. Treatment of crude 
benzine, 73. 

Treatment of Petroleum Residues : A. Mineral lubricating oils, 74 ; 
requirements and analysis of lubricating oils, 77. B. Vaseline, gelatinised 
vaseline oil, 80. C. Paraffin wax, 80; different sources: (1) pyropissite, 
81 ; tar, 81 ; photogen, 82 ; tar, asphalt, pitch, and bitumen, 83 ; 
(2) bituminous shale, 83 ; (3) ozokerite and cerasin, 85. 

(ft) UNSATURATED HYDROCARBONS 87 

T. Ethylene Series (alkylenes or olefines), C ra H 2n , 87 ; official nomen- 
clature, 87 ; constitution, methods of preparation, 88. Ethylene, propylene, 
butylenes, amylenes, cerotene, and melene, 89-90. 

II. Hydrocarbons of the Series C w H 2n _ 2 : A. With two double Unkings 
(diolefines or allenes) : allene, erythrene, isoprene, piperylene, diallyl, conylene, 
90. B. With a triple linking (acetylene series) : metallic acetylides, acety- 
lene, 90-94. 

III. Hydrocarbons of the Series C n H 2M _ 4 and C n ~H 2 n-6' 94. 



BB. HALOGEN DERIVATIVES OF HYDROCARBONS 

Table of the halogen derivatives f)5 

I. Halogen Derivatives of Saturated Hydrocarbons : properties, 94 ; 
preparation, 95-96. Methyl chloride, 96. Methyl iodide, 97. Ethyl 
chloride, 97. Isopropyl iodide and butyl iodides, 97. Methylene, ethylene, 
and ethylidene halogen derivatives, 98. Chloroform, 98-100. lodoform, 100. 
Polychloro-derivatives, 101. 

II. Halogen Derivatives of Unsaturated Hydrocarbons, 102; allyl 
chloride, 102. 

CC. ALCOHOLS 

I. SATURATED MONOHYDRIC ALCOHOLS 103 

Nomenclature, 102. Methods of formation of monohydric alcohols. 104. 
Table of monohydric saturated alcohols, 105. Methyl Alcohol, 106-108. 
Ethyl Alcohol, 108. Solid alcohol, 109. Bacteriology, 110. Enzymes, 111. 
Oxydases, peroxydases, 112. Biogen hypothesis, toxins, liquid crystals, 
origin of life, 114. Industrial preparation of alcohol : prime materials, 116. 
Alcoholic fermentation, 121. Yeasts and ferments, 122. Factors facilitating 
or retarding fermentation, 126. Losses and yields, 128. Table for the 
calculation of the attenuation of fermented saccharine worts, 130. Dis- 
tillation of fermented liquids, 132. Rectification of alcohol, 138. Other 
raw materials for alcohol manufacture, 140. Alcohol from fruit, 141. 
Alcohol from woody matter, 142. Alcohol from wine, lees, withered grapes, 
143. Refining and depuration of spirit, 144. Fusel oil, 144. Alcohol 
meters, 146. Alcoholometry and tests for alcohol, 146. Windisch's table, 
148. Alcoholism and alcohol-free wines, 150. Statistics, 149. Denatured 
alcohol for industrial purposes, 152. Distillery residues, 153. 



CONTENTS xi 

PAGE 

Alcoholic Beverages : Wine, 155. Marsala, 159. Vermouth, 159. Cider,"] 
159. Liqueurs, 159. Fermented milk (kephir, koumiss), 160. 

Beer, 161 : barley, hops, water, germination, kilning of malt, mashing, 
Balling's table, 161-168 ; infusion and decoction mashing, 168 ; boiling of 
the wort with hops, 170 ; fermentation, 171 ; attenuation, 174. The 
Nathan-Bolze rapid process, 175 ; racking, pitching of casks, 176 ; pasteurisa- 
tion, 177 ; alcohol-free beer, 178 ; composition of beer, 178 ; analysis of 
beer, 178; statistics, 179. 

Higher Alcohols, 180 ; propyl, butyl, amyl, &c., 180. 

II. UNSATURATED MONOHYDRIC ALCOHOLS : vinyl, allyl, propargyl, 

&c., 182. 

III. POLYHYDRIC ALCOHOLS. (A) Dihydric Alcohols or glycols, 182. (B) Tri- 
hydric alcohols.- glycerol, 183. (C) Tetra- and poly-hydric alcohols: acetyl 
number, 188. Erythritol, arabitol, mannitol, dulcitol, sorbitol, 189-190. 



DD. DERIVATIVES OF ALCOHOLS 

(A) DERIVATIVES OF MONOHYDRIC ALCOHOLS 190 

I. Ethers, 190 ; methyl ether, 192 ; ethyl ether : properties, industrial 
preparation, 192. 

II. Thioalcohols and Thioethers, 195. 

III. Alkyl Derivatives of Inorganic Acids, 196: (1) of sulphuric acid, 
197 ; (2) of sulphurous acid, 197 ; (3) of nitric acid, 197 ; (4) of nitrous acid, 
197 ; (5) nitro-derivatives of hydrocarbons, 197 ; (6) various acids, 198 ; 
(7) Derivatives of hydrocyanic acid : (A) Nitriles ; (B) Isonitriles, 198-199. 

IV. Alkyl Nitrogenous Basic Compounds (amines), 200 ; methylamine, 
dimethylamine, ethylamine, 201 ; triethylamine, 202 ; alkylhydrazines, 
azoimides, a- and /3-alkylhydroxylamines, diazo- compounds, 202. 

V. Phosphines, Arsines, and Alkyl-metallic Compounds. Grignard 
reaction, 202-203. 

VI. ALDEHYDES AND KETONES 204 

(a) Aldehydes : Functions, constitution, chemical properties, 204. 
Aldoximes, hydrazones, semicarbazones, hydroxamic acid, 206. Form- 
aldehyde : preparation, properties and analysis, 206. Acetaldehyde, 
acetal, 208. Higher aldehydes, 209. Chloral and its hydrate, 209. 
Aldehydes with unsaturated radicals : acrolei'n, crotonaldehyde, citral, 
&c., 209. 

(6) Ketones : Properties, preparation, 210. Acetals, sulphonal, 
thioketones, ketoximes, phenylhydrazones, isonitrosoketones, 210. 
Acetone, 211 ; mesityl oxide, phorone, butanone, 212. JCetenes, 212. 

(B) DERIVATIVES OF POLYHYDRIC ALCOHOLS 213 

Glycolsulphuric acid, Ethylenecyanohydrin, Ethylene oxide, 213; Taurine, 
Glycide alcohol, Glycerophosphoric acid, 214. Nitric ethers of glycerol, 215. 

Explosives : Theory of explosives, 215. Chemical reactions of explosives : 
heat of explosion, 216 ; temperature of ignition, 217 ; mechanical work of 
' explosives, 217 ; pressure of the gases, 218 ; charging density, 218 ; crushers, 
219; specific pressure, 219. Velocity of explosion, 219; shattering and 
progressive explosives, 219 ; velocity of combustion, 219 ; initial shock 
and course of explosion, 220 ; determination of explosion, 220 ; explosive 
wave, 221 ; explosion by influence, 221. Classification of explosives, 222. 
Nitroglycerines, 222. Trinitroglycerine, 223. Manufacture of nitroglycerine, 
225. Dynamites, 229 : with inactive bases, 230 ; with active bases, 230. 



xii CONTENTS 

PAGE 

Nitrocellulose, 232. Guncotton : preparation, manipulation, compression, 
233-239. Collodion cotton for gelatines, 239. Smokeless powders, 240. 
Powders with picrate bases, 245. Explosives of the Sprengel type, 245. 
Safety explosives, 246. Black powder, 248. Various powders, 254. Deto- 
nators, 255. Mercury fulminate, 255. Caps, cartridges, fuses, 255. Destruc- 
tion of explosives, 256. Storage and preservation of explosives, 258. Analysis 
of explosives, 259. Ballistic tests of explosives, 261. Uses, 263. Statistics, 
263. 

EE. ACIDS 

I. MONOBASIC SATURATED FATTY ACIDS, C n H 2n 2 264 

Table, 265. General methods of preparation, 264. Coefficients of affinity, 
266. Separation, 267 ; constitution, 268. Formic Acid, 268. Acetic Acid, 
270 : Oudemann's table of specific gravity, 271 ; tests and manufacture, 272 ; 
distillation of wood, 272 ; utilisation of wood-waste, 274 ; pyroligneous acid, 
276 ; calcium acetate, 277. Uses, statistics, and price of acetic acid, 279. 
Manufacture of vinegar, 280. Analysis of vinegar, 284. Salts of Acetic Acid : 
potassium, sodium, ammonium, calcium, ferrous and ferric acetates, 285 ; 
neutral and basic aluminium acetates, silver acetate, neutral and basic lead 
acetates, chromic, stannous, and copper acetates, 286-287. Propionic Acid, 
288. Butyric Acids : (1) Normal butyric acid, 288 ; (2) isobutyric acid, 288. 
Valeric Acids : (1) Normal valeric acid ; (2) isovaleric acid ; (3) ethylmetliyl- 
acetic acid ; (4) trimethylacetic acid, 288. Higher Acids : Caproic, heptylic, 
caprylic, nonoic, undecoic, lauric, myristic, 289. Palmitic Acid, 289. Margaric 
acid, 293. Stearic acid, 290. Cerotic acid, 290. 

II. MONOBASIC UNSATURATF.D FATTY ACIDS 291 

A. OLEIC OR ACRYLIC SERIES : Table, 291. General method of 
formation, 291 : general properties, 292. Acrylic Acid, C 3 H 4 2 , 294. 
Crotonic Acids, C 4 H 6 2 : (a) vinylacetic acid 294 ; (bn) solid crotonic acid, 
295 ; (bft) liquid crotonic acid, 295 ; (c) methylmethyleneacetic acid, 296. 
Pentenoic Acids, C 5 H 8 O 2 : (a) angelic acid, 296 ; (b) tiglic acid, 296. 
Pyroterebic Acid, C 6 H 10 2 , 297. -y-Allylbutyric Acid, C 7 H 12 2 , 297. 
Teracrylic Acid, C 8 H 14 2 , 297. Citronellic Acid, C 10 H 18 O 2 : rhodinic 
acid, 298. Undecenoic Acid, C 11 H 20 2 , 298. Hypogseic Acid, C 16 H 30 O 2 , 
298. Oleic Acid, C 18 H 34 O 2 , 298 ; Elaidic Acid, 298 ; Iso-oleic Acid, 

299 ; A a 0-oleic acid, 299. Erucic Acid, C 22 H 42 2 , 300 ; Brassidic Acid, 

300 ; Isoerucic Acid, 300. 

B. UNSATURATED ACIDS OF THE SERIES C n H 2n _ 4 O 2 300 

(a) Acids with a Triple Linking (propiolic series) : Table, 300. Pre- 
paration, 300 ; properties, 301. Propiolic Acid, C 3 H 2 2 . Tetrolic 
Acid, C 4 H 4 O 2 . Dehydroundecenoic Acid, C U H 18 2 , 301. Undecolic 
Acid, 302. Stearolic Acid, C 18 H 32 O 2 . Tariric Acid. Behenolic 
Acid, C 22 H 40 2 , 302. 

(b) Acids with two Double Linkings (diolefine series), 302. /3-Vinyl- 
acrylic Acid, C 6 H 6 O 2 . Sorbinic Acid, C 6 H 8 2 . Diallylacetic Acid, 
C 8 H 12 2 . Geranic Acid, C 18 H 32 2 . Linolic Acid ; Drying oils, 303. 
a-Elaeostearic Acid, 304. 

C. ACIDS WITH THREE DOUBLE LINKINGS, C n H 2w _ 6 2 . Citrylidene- 
acetic Acid, C 12 H 18 O 2 . Linolenic and Isolinolenic Acids, C 18 H 30 2 . 
Jecorinic Acid, C 28 H 30 2 , 304. 

ITI. POLYBASIC FATTY ACIDS 304 

A. SATURATED DIBASIC ACIDS, C M H 2w (C0 2 H) 2 , 304; Table, 305; 
preparation, properties, 305. Oxalic acid, C 2 H 2 4 , 306. Salts of oxalic acid, 
307. Malonic Acid, C 3 H 4 O 4 , 308. Table of malonic acid derivatives, 308. 



CONTENTS xiii 

PACE 

Ethyl Malonate, its use in syntheses, 308. Succinic Acid, C 4 H 6 O 4 , 310. 
Homologous derivatives, 310. Isosuccinic Acid, 311. Pyrotartaric acids, 
C 4 H 9 O 4 : glutaric acid, pyrotartaric acid, 311. Higher Homologues, 311. 

ft-Methyladipic and azelaic acids, 311. 

B. UNSATURATED DIBASIC ACIDS, C w H 2n _ 4 O 2 312 

OLEFINEDICARBOXYLIC ACIDS: Table, 312. Fumaric Acid, 313. 
Maleic Acid, C 4 H 4 4 . Itaconic Acid, C 5 H 6 4 . Mesaconic Acid, C 5 H 6 O 4 . 
Citraconic Acid, C 5 H 6 4 . Glutaconic Acid, C 5 H 6 O 4 . Pyrocinchonic 
Acid and Anhydride, C 6 H 8 4 . Korner and Menozzi reaction of amino- 
acids. Hydromuconic Acid, C 6 H 8 O 4 . Diolefinedicarboxylic Acids. 
Acetylenedicarboxylic Acids, 313-315. 

C. TRIBASIC ACIDS, &c. 315 
Tricarballylic Acid, C 3 H 5 (COOH) 3 . Camphoronic Acid, C 9 H 14 O 6 . 

Aconitic Acid, C 6 H 6 6 , 315. 

D. TETRABASIC ACIDS 31 G 



FF. DERIVATIVES OF ACIDS 

I. HALOGEN DERIVATIVES 310 

(a) Halogenated Acids, 316. Cyano-acids. Monochloracetic Acid, 317. 
Table of the halogenated acids, 318. 

(b) Acid Halides : chloranhydrides ; acetyl chloride ; acetyl iodide, &c., 
317-319. 

II. ANHYDRIDES 319 

Properties, preparation, Table, 319-320. Acetic Anhydride, 320. 

III. HYDROXY-ACIDS 320 

A. SATURATED DIVALENT MONOBASIC ACIDS 

Preparation, properties, constitution ; lactides ; lactones, 321. 

Glycollic Acid, OH-CH 2 -COOH, and its derivatives (anhydride, glycollide, 
&c.), 322. Glycocoll, 322. 

Lactic Acids, C 2 H 4 (OH)(COOH) : (1) i-Ethylidenelactic acid (of fermen- 
tation), 323 ; Alanine, 325. (2) d-Ethylidenelactic (or sarcolactic) acid. 
(3) 1-Ethylidenelactic acid. (4) Ethylenelactic acid, 325. 

Hydroxybutyric Acids, C 3 H 6 (OH)(COOH) : a-Hydroxybutyric acid. 
a-Hydroxyisobutyric acid. /3-Hydroxybutyric acid, 326. 

Higher Hydroxy-Acids : Hydroxy valeric, hydroxycaproic, hydroxy- 
myristic, hydroxypalmitic, hydroxystearic, 326. 

B. UNSATURATED MONOBASIC HYDROXY-ACIDS 32(5 
a-, ft-, y, and 8-Hydroxyolefinecarboxylic acids : Ricinoleic acid ; ricino- 
leinsulphonic acid and Turkey-red oil (sulphoricinate), 326-328. 

C. POLYVALENT MONOBASIC HYDROXY-ACIDS 328 
Glyceric Acid, 2 H 3 (OH) 2 (COOH). Dihydroxystearic acid, C 17 H 33 (OH) 2 - 

COOH, Erythric Acid, C 3 H 4 (OH) 3 -COOH. Penfonic acids. Arabonic Acid. 
Hexonic Acids, 328. Heptonic Acids, 329. 

D. MONOBASIC ALDEHYDIC ACIDS (Aldehydic Alcohols and 
Dialdehydes) 329 

Glyoxylic Acid C0 2 H -CHO. Glycuronic, Forrnylacetic, and /3-Hydroxy- 
acrylic Acids, 329. 



xiv CONTENTS 

PAGE 

Glycollic Aldehyde, OH -CH 2 -CHO. Glyceraldehyde. Aldol. Glyoxal, 321). 

E. MONOBASIC KETONIC ACIDS (Keto-alcohols, Diketones, and 
Keto-aldehydes) 330 

General properties. Methods of preparation, a-, ft-, and y-Ketonic acids. 
Syntheses with ethyl acetate, 330-331. Pyruvic Acid, 331. Acetoacetic Acid. 
Ethyl Acetoacetate, 332. Levulinic Acid, 333. 

KETONIC ALCOHOLS : Acetonealcohol. Dihydroxyacetone. 
Butanolone, 333. 

DIKETONES : Diacetyl. Acetylacetone, 333-334. 

KETO-ALDEHYDES : Pyruvic Aldehyde and Acetoacetaldehyde. 
Hydroxymethyleneacetone. 334. 

F. POLYVALENT DIBASIC HYDROXY-ACIDS AND THEIR 
DERIVATIVES 334 

Tartronic Acid, 334. Malic Acid and higher homologues, 335. 

TARTARIC ACIDS: (1) d-Tartaric Acid, 335. (2) 1-Tartaric Acid. 
(3) Racemic Acid. (4) Mesotartaric Acid, 336. 

TARTAR INDUSTRY : Manufacture of Tartar, 337. Analysis of 
tartar, 337. Statistics, 340. Manufacture of tartaric acid, 341 ; uses and 
statistics, 343. Artificial tartaric acid, 343. Trihydroxyglutaric Acid, 
343. Saccharic and Mucic Acids, 344. 

DIBASIC KETONIC ACIDS, 344. Mesoxalic Acid. Oxalacetic Acid. 
Acetonedicarboxylic Acid. Dihydroxytartaric Acid, 344. 

G. POLYVALENT TRIBASIC HYDROXY-ACIDS 345 
Tricarballylic Acid. Aconitic acid. Citric Acid and its Industry, 

345. Tests for citric acid, 346. Salts of citric acid, 346. Citrates, 346-347. 
Citrus industry, 347. Statistics, 349. Higher polybasic hydroxy-acids, 351. 

IV. THIO-ACIDS AND THIO-ANHYDRIDES 351 

Thioacetic Acid. Ethanthiolic Acid. Acetyl Sulphide. Ethyl Thioacetate. 

V. AMIDO-ACIDS, AMINO-ACIDS, IMIDES, AMIDINES, THIOAMIDES, 

IMINO-ETHERS AND ANALOGOUS COMPOUNDS 351 

A. Amido-Acids and their Derivatives : Primary, secondary, and tertiary 
amides ; alkylated amides. Preparation and properties of amides, 351-352. 

Formamide ; Acetamide, diacetamide ; Oxamic Acid ; Oxamide ; 
Succinamic Acid ; Succinamide ; Glycollamide, diglycollimide ; Malamic 
Acid, malamide, 352-353. 

B. IMIDES AND IMINO-ETHERS: diacetamide, iminohydrin of 
glycollic acid ; Oximide, Succinimide, pyrrole, pyrrolidine, succinanil ; 
Glutarimide, 353-354. 

C. AMINO-ACIDS AND THEIR DERIVATIVES: Glycocoll, sarco- 
sine, betaine, aceturic acid ; Serine ; Leucine ; Aspartic Acid, glutamic 
acid ; Ethyl Diazoacetate ; Lysine, ornithine, putrescine, taurine, cysteine, 
cystine ; Asparagine, Aspartamide, homoaspartic acid and homoasparagine, 
354-356. 

D. AMIDO- AND IMIDO-CHLORIDES : acetamido-chloride, acetimino- 
chloride, 356. 

E. THIOAMIDES : thioacetamide, 367. 



CONTENTS xv 

PAGE 

F. IMINOTHIOETHERS : acetiminothioinethyl hydriodide, 357. 

G. AMIDINES : acetamidine, 357. 

H. HYDRAZIDES AND AZIDES : diaccthydrazide, 358. 

I. HYDROXYLAMINE DERIVATIVES OF ACIDS : hydroxamic acids, 
amidoximes, isuret, 358. 

VI. CYANOGEN COMPOUNDS 358 

Cyanogen : paracyanogen ; rubeanhydric acid and flaveanhydric acid. 
Cyanogen Chloride, 358-359. Cyanic Acid : potassium and ammonium 
cyanates, 359. Ethyl Isocyanate, 359. Cyanuric Acid : Ethyl cyanurate 
and isocyanurate, 359. Fulminic Acid, 360. 

THIOCYANIC ACID AND ITS DERIVATIVES, 360. Potassium, 
Ammonium, Mercuric, Silver, and Ferric Thiocyanates, 361. Ethyl 
Thiocyanate. Allyl Thiocyanate, 361. 

MUSTARD OILS : methyl, ethyl, propyl, Allyl, 361. 

CYANAMIDE AND ITS DERIVATIVES, 362. Calcium cyanamide, 362. 
Diethylcyanamide. Dicyanodiamide. Melams : Melamine, Ammeline, 
Ammelide, 362. 

VII. DERIVATIVES OF CARBONIC ACID 362 

Esters of carbonic acid. Ethyl carbonate, ethylcarbonic acid, 363. 
Chlorides of Carbonic Acid. Chlorocarbonic acid, ethyl chlorocarbonate 
and chloroformate, 363. Amides of Carbonic Acid. Carbaminic acid, 
urethane, urea, semicarbazide, acetylurea, allophanic acid, ureides, biuret, 
hydantoic acid, hydantoin, 363-364. 

DERIVATIVES OF THIOCARBONIC ACID : thiophosgene, trithio- 
carbonic acid, potassium xanthate, xanthonic acid, dithiocarbamidic acid, 
diethylthiourea. Thiourea, 364-365. 

GUANIDINE AND ITS DERIVATIVES : nitroguanidine, aminoguani- 
dine, diazoguanidine, hydrazo- and azo-dicarbonamide, glycocyamine, sar- 
cosihe, creatine, creatinine, 365-366. 

URIC ACID AND ITS DERIVATIVES : ureides, uro-acids, diureides ; 
parabanic acid, barbituric acid, dialuric acid, alloxan, oxaluric acid, alloxanic 
acid, cholestrophane, methyluracil, alloxanthine, murexide, allantoin, purine, 
dimethylpseudouric acid, theophylline, caffeine, theobromine, hypoxanthine, 
xanthine, adenine, guanine, uric acid, adenine, 366-369. 

VIII. ESTERS (Oils, Fats, Waxes, Candles, Soaps) 309 
Preparation : theory of the formation of esters ; fruit essences : ethyl 

formate, ethyl acetate, amyl acetate, ethyl butyrate, isoamyl isovalerate, cetyl 
and melissyl palmitates, ceryl cerotate, 369-372. 

Glycerides, Fatty Oils, Waxes, Candles, Soaps, 372. 

Tripalmitin, tristearin, triolein, lecithin ; serum-lipase, drying oils, varnishes ; 
rancidity of oils, blown oils, 372-376. 

Waxes : beeswax, virgin wax, white wax, carnauba wax, Japanese 
wax, 376-377. 

Saponifi cation of Fats and Waxes, 377. Table of physical and chemical 
constants, 378. 

ANIMAL OILS AND FATS, 379 : tallow, 380 5 oleomargarine, 382 ; 
margarine, 383; butter, 385; milk, 385; bone fat, 388; lard, 388; fish oils, 
sperm oil, cod-liver oil, spermaceti, 389 ; degras : wool-fat, 389. 

VEGETABLE OILS, 390 : Table, 391 ; extraction by pressure, hydraulic 
press, extraction by solvents, refining, emulsor-centrifuges and centrifugal 
separators, 391-395 ; olive oil, 395 ; castor oil, 398 ; linseed oil, 39$ ; oil 



xvi CONTENTS 

varnishes and lacs, 400 ; palm oil, palm-kernel oil, 401 ; coco-nut oil, 402 ; vege- 
table tallow, 403 ; cotton-seed oil, 403 ; maize oil, 403 ; sesame oil, 404 ; arachis, 
soja bean, grape-seed and tomato-seed oils, 404-405. 

TREATMENT OF FATS FOR CANDLES AND SOAPS: (1) saponi- 
fication with lime, magnesia, or zinc oxide ; (2) decomposition with sulphuric 
acid ; oleine of distillation ; transformation of oleic acid into solid fatty acids ; 
(3) saponification with water ; (4) biological process ; (5) catalytic process 
(Twitchell), 405-411. 

MANUFACTURE OF CANDLES, 412. De Schepper and Geitcl's 
Table, 413. 

MANUFACTURE OF SOAP, 415. Theory of saponification, 416. Fatty 
acid or oleine soap, 419. Resin soap, 420. Mottled soap, 421. Transparent 
soap, 422. Soft soap, 422. Statistics, 424. Analysis of soap, 425. 



GG. ALDEHYDIC OR KETONIC POLYHYDRIC ALCOHOLS 

CARBOHYDRATES 

A. Monoses 426 
Aldohexoses, ketohexoses, osazones, hydrazones ; general methods of 

formation of monoses, 426-428. Tetroses and Pentoses : pentosans, 
arabinose, xylose, rhamnose, &c., 429-431. Hexoses : glucose, caramel ; 
fructose ; mannose ; galactose, 431-437. Glucosides, 437. 

B. Hexabioses 438 
Maltose, lactose, 438. Sucrose : calcium sucrate, 440. 

C. Trioses. Raffinose 442 

INDUSTRIAL PREPARATION OF SUCROSE 442 

I. Acer saccharinum nigrum, 443. II. Sugar-cane, 443. III. Sugar beet, 
445 : cultivation, composition, 446 ; extraction of sugar from beet, 448 ; extraction 
by diffusion, 450 ; extraction by the Steffen process, 456 ; filter-presses, 459 ; 
concentration of the juice, 461 ; boiling of the concentrated juice, 466 ; centri- 
fugation of the, massecuite, 468 ; refining, 470 ; revivification of animal charcoal, 
470 ; utilisation of molasses : osmosis, lime, strontia, baryta processes, 473. 
Yield, 476. Statistics, 477. Fiscal relations, 477. Density table, 482. 
Quantitative analysis of saccharine materials, 481. Stammer's table, 482. 
Polarimeters and saccharimeters, 483. Scheibler's table, 483. Chemical tests, 
486. Non-sugar, apparent and real densities, quotient of purity, 487. Purifi- 
cation of waste-liquors from sugar factories, 489. 

D. Tetroses 489 

E. F. Higher polyoses . 489 

Starch, 489. Analysis, 500. Dextrin, 501. Gums, 502 ; glycogen, 503. 
Cellulose, 503. Hydro- and oxy- cellulose. 504-506. Artificial parchment, 
506. Paper industry, 506. Statistics, 517. 



PART III. CYCLIC COMPOUNDS 

A A. ISOCYCLIC COMPOUNDS 520 

I. Cydoparajfins and cyclo-olefines or polymethylene compounds, 520. 
II. Benzene derivatives or aromatic compounds : the formula of benzene, 
521. Isomerism in benzene derivatives, 523. General character and forma- 
tion of benzene derivatives, 524-525, 



CONTENTS xvii 

PAGE 

A. AROMATIC HYDROCARBONS 526 

Distillation of tar, 526. Table, 527. Lampblack, 528. Tar oils, 531. 
Preservation of wood, 532. Benzene, 533. Toluene and xylenes, 534. 
Hydrocarbons with unsaturated side-chains, 535. 

B. HALOGEN SUBSTITUTION DERIVATIVES OF BENZENE 536 
Table, 537. 

C. SULPHONIC ACIDS 538 

Benzenesulphonic acid, 538. ' 

D. PHENOLS 539 

(a) Monohydric phenols, 539. Table, 540. Carbolic acid, 541. Antiseptics, 
541. Homologues, 543. (b) Dihydric phenols : pyrocatechol, resorcinol, 
hydroquinone, orcinol, eugenol, isoeugenol, 543. (c) Trihydric phenols : 
pyrogallol, hydroxyhydroquinone, phloroglucinol, 545. (d) Polyhydric 
phenols : hexahydroxybenzene, quercitol, inositol, 546. 

E. QUINONES 546 

F. NITRO-DERIVATIVES OF AROMATIC HYDROCARBONS 547 

Table, 548. Nitrobenzene, dinitrobenzenes, nitrotoluenes, trinitrotoluenes, 
phenylnitromethane, pseudo-acids, 649-654. 

G. AMINO-DERIVATLVES OF AROMATIC HYDROCARBONS 554 
Table of Aromatic Amines, 555: (1) primary monamines ; (2) secondary 

monamines ; (3) tertiary monamines; (4) quarternary bases; (5) diamines, 
Iriamines, tetramines. Aniline, nitraniline, methylaniline, diphenylamine 
acetanilide, exalgin, phenylsulphaminic acid, 554560. Homologues of aniline : 
toluidines, xylidines, benzylamine, phenylenediamine, 560-562. 

H. NITROPHENOLS, AMINOPHENOLS, AND THIOPHENOLS 562 

Nitrophenol, picric acid, aminophenols, thiophenols, 562-564. 

I. AZO- DIAZO- AND DIAZOAMINO-COMPOUNDS AND 

HYDRAZINES 565 

(1) Azo- derivatives ; (2) diazo-derivatives ; (3) diazoamino- derivatives 
(4) hydrazines, 565-570. 

L. AROMATIC ALCOHOLS, ALDEHYDES, AND KETONES 570 

Benzyl alcohol, benzaldehyde and its homologues, cinnamaldehyde, 
570-572. Aromatic ketones, 572. Aromatic oximes, 572. Beckmann 
rearrangement, 573. 

M. HYDROXY - ALCOHOLS, HYDROXY - ALDEHYDES, AND 

KETONIC ALCOHOLS 673 

Salicylaldehyde, anisaldehydei vanillin, 573. Aromatic hydroxy-alde- 
hydes, 674. 

N. AROMATIC ACIDS 57 

General methods of preparation and properties, 575. 

(a) MONOBASIC AROMATIC ACIDS, 576. Table, 677. Benzole 
anhydride, benzoyl chloride, benzamide, hippuric acid, chlorobenzoic acid, 
m-nitrobenzoic acid, azobenzoic acids, aminobenzoic acids (anthranilic 
acid), diazobenzoic acids, anthranil, sulphobenzoic acids, saccharin, 
toluic acids, phenylacetic acid, xylic acids, cuminic acid, cinnamic acid, 
phenylpropiolic acid, 578-580. 
II b 



xviii CONTENTS 

PAGE 

(6) DIBASIC AND POLYBASIC AROMATIC ACIDS, 580 . phthalic 
acid, phthalic anhydride, phthalide, phthalophenone, phenolphthalein, 
fluorescein, eosin, phthalimide, isophthalic acid, terephthalic acid ; 
polybasic acids : mellitic acid, 580-581. 

(c) HYDROXY- ACIDS OR PHENOLIC ACIDS, 582; salicylic 
acid, m- and p-hydroxybenzoic acids, gallic acid, ink, cumaric and 
mandelic acids. Tannin, tanning of skins, commercial data, 582-591. 

0. HYDROGENATED BENZENE COMPOUNDS 591 

Hydrophthalic acids. Terpenes, cymene, carvene, 1-limonene, sylvestrene, 
terpinolene, terpinene, dihydrocymene, phellandrene, menthene, menthane, 
591-596. Complex Terpenes, pinene, oil of turpentine, colophony, camphene, 
fenchene, camphane ; rubber, ebonite, guttapercha, ionone, 596-600 ; camphors, 
terpane, menthol, pulegone, carvone, terpenol, terpineol, terpin, cineol ; 
camphor, artificial camphor, 600-605. 

P. CONDENSED BENZENE NUCLEI 605 

(1) Diphenyl and its derivatives : diphenyl, benzidine, carbazole, di- 
hydroxyphenyl, &c., 605. (2) Diphenylmethane and its derivatives : dihy- 
droxybenzophenone, diphenylethano, tolylphenylmethane, benzoylsulphonic 
acids, fluorene, 606. (3) Triphenylmethane and its derivatives : leuco-bases, 
malachite green, pararosaniline, rosaniline, fuchsine, methyl violet ; rosolic 
acid, phthalophenone, hexaphenyle thane, and pentaphenylethane, 607. 
(4) Dibenzyl and its derivatives, 609. (5) Naphthalene and its derivatives : 
naphthalene, hydronaphthalene, perinaphthalenecarboxylic acid, a-nitro- 
naphthalene, a-naphthylamine, naphthalenesulphonic acids, o- and /3- 
naphthols, dinaphthol, betol : naphthionic acid, a- and /3-naphthaquinones, 
naphthalic acid, dinaphthyl, acenaphthene, 610-614. Addition products of 
naphthalene. Indene, 614. (6) Anthracene group : anthracene, carbazole, 
anthraquinone, alizarin, 614-618. Phenanthrene, phenanthraquinone, fluor- 
anthrene, pyrene, chrysene, picene, retene, 618-619. 

Q. HETEROCYCLIC COMPOUNDS <Hfl 

(1) Furfuran : furfural, furfuryl alcohol, pyromucic acid, 619. (2) Thio- 
phene, 620 ; thioxene, indophenin. (3) Pyrrole : iodol, pyrocoll, nitrosopyrroles, 
hydropyrroles ; pyrazole, pyrazolone, antipyrine, 620-623. (4) Pyridine 
ani its derivatives (alkaloids) : pyridine, picoline, lutidine, collidine, pyridones, 
pyridinecarboxylic acids, hydropyridines, piperidine, 623-626. Alkaloids : 
Separation and tests, 627 ; Table, 628 ; synthesis of alkaloids and medicine ; 
anaesthetics ; coniine, nicotine (tobacco), atropine. morphine, cocaine, narco- 
tine, strychnine, brucine, curarine quinine, 627-635. (5) Quinoline and 
its derivatives : quinaldine ; isoquinoline. I satin. Indoxyl. Skatole. Indole. 
Indazole, 635-639. Indigo, natural and artificial ; analysis ; various syntheses ; 
statistics, 639-646. 

R. COLOURING-MATTERS (Xfi 

Dichroic substances ; chromophores, chromogens, auxochromes. Rosani 
line. Process of dyeing. Basic, acid, and neutral colouring- matters. Lakes. 
Mordants, 646-651. Behaviour of colouring- matters with respect to various 
fibres and mordants, according to Noelting, 651. Manufacture of colouring- 
matters, 652. Statistics of production, 653. Classification of colouring-matters : 
I. Nitro- colouring- matters. II. Azo- colouring- matters. III. Derivatives 
of hydrazones and pyrazolones. IV. Hydroxyquinones and quinoneoximes. 
V. Diphenyl- and triphenyl- methane colouring- matters. * VI. Derivatives ot 
quinonimide. VII. Aniline black. VIII. Quinoline and acridine derivatives. 
IX. Thiazole colouring- matters. X. Oxyketones, xanthones, flavones, and 
coumarins. XI. Indigo and similar and other natural colouring-matters : 
indanthrene group ; logwood ; archil ; cochineal ; yellow wood (Cuba wood) ; 
quercitron; natural Indian yellow ; redwood (Brazil wood); sandal wood 
catechu; gambier; chlorophyll. XII. Sulphur colouring- matters, 654 671. 



CONTENTS xix 

P.UiE 

TESTING OF COLOURING-MATTERS 671 

Examination of mixtures of colouring-matters, 671-680. 
Recognition of the principal colouring. matters on dyed fibres (Table), 
674-679. 

TEXTILE FIBRES 8I 

Wool : different breeds of sheep ; combed and carded wool ; shoddy ; 
statistics ; count of yarn ; imports and exports ; chemical properties of wool, 
681-684. Cotton: mercerised cotton; statistics, 684-686. Flax, 686. 
Hemp, 688. Jute, 689. Silk : rearing of the silkworm ; treatment of 
cocoons ; spinning and twisting ; silk waste ; cleansing and dyeing ; deter- 
mination of the weighting of silk ; statistics of silk and cocoons, 690-698. 
Sea silk, 698. Artificial silk : history ; dyeing ; output, 698-703. 

QUALITATIVE TESTS FOR DIFFERENT TEXTILE FIBRES 703 

QUANTITATIVE ANALYSIS OF MIXTURES OF TEXTILE 
FIBRES: conditioning; moisture; dressing; mixed cotton and wool ; cotton 
and silk ; natural and artificial silk ; cotton and linen, 704-705. 

DYEING AND PRINTING TESTS ON TEXTILE FIBRES 705 

FASTNESS TESTS 707 

THEORY OF DYEING 708 

MACHINERY USED IN DYEING AND FINISHING TEXTILE 
FIBRES, 711. Washing and preparation; bleaching; milling; carbonisation ; 
fixing of fabrics ; crabbing ; dyeing plant ; jiggers ; dryers ; tentering 
frames ; raising gigs ; calendars ; cutters ; steaming ; dressing ; finishing ; 
pressing ; mercerisation ; printing of fabrics and yarns ; oxidation chamber 
for aniline black; polishing of silk, 711-713. 

S. PROTEINS OR ALBUMINOIDS 733 

Characteristic reactions of the proteins ; hydrolysis and synthesis ; 
polypeptides, 733-735. I. Natural Proteins : (1) Albumins (egg- and 
blood-), egg-industry. (2) Globulins. (3) Nucleo-albumins. (4) Proteins 
which coagulate. (5) Histones. (6) Protamines, 735-737. II. Modified 
Proteins : (1) Albumoses and peptones. (2) Salts of proteins, 737. 
III. Conjugated Proteins (Proteids) : (1) Haemoglobin. (2) Nucleo- 
proteins. (3) Glucoproteins, 737-739. IV. Albuminoids: (1) Elastin. 
(2) Keratin. (3) Collagens. Manufacture of glue and gelatine, 739. 
V. Various Proteins, 740. 

GLUCOSIDES AND OTHER SUBSTANCES OF UNCERTAIN OR 
UNKNOWN COMPOSITION : Amygdalin ; saponin ; digitalin ; salicin ; 
aesculin ; populin ; hesperidin ; phloretin ; iridin ; arbutin ; coniferin ; 
sinigrin ; santonin ; aloin ; lecithin ; cerebrin ; iodothyrin ; taurocholic, 
glycocholic, and cholic acids ; biliverdin, bilif uchsin, and bilirubin ; cantharidin ; 
chitin ; cholesterol, 740-742. 

INDEX 743 



ERRATUM 

Page 386, line 28, for gallatite read gallalith 



PART I. GENERAL 

IN vol. i of this treatise l is given a brief summary of the history of chemistry 
and of those portions of physico-chemical theory which are necessary for the 
interpretation of chemical phenomena. 

Hence, this course of organic chemistry assumes in the reader a knowledge 
of the fundamental chemical laws and ideas, methods of determining molecular 
weights, and so on. 

The separate treatment of the carbon compounds, which is termed organic 
chemistry, is a purely didactic convenience and somewhat of a habit, there 
being no sound foundation to justify a distinction between organic and inorganic 
chemistry. 

This division of the subject dates back to the time of Lemery, who, in 
1675, regarded the substances of the animal and vegetable kingdoms as distinct 
from those of the mineral kingdom, and to 1820, when Berzelius justified the 
separation by stating that the preparation of organic compounds required the 
intervention of vital force, whilst inorganic compounds could be prepared 
artificially in the laboratory. But this view was abandoned in 1828, when 
Wohler succeeded in preparing urea (found in urine) from inorganic material 
in the laboratory, and, later, when acetic acid was prepared artificially. Sub- 
sequently, the number of so-called organic compounds which have been 
obtained synthetically has increased almost without limit. 

There exists to-day no reason for a distinction between organic and inorganic 
compounds ; the first comprise a group of carbon compounds ^ embracing an 
immense number (over 150,000) of substances, which exhibit certain common 
characters and are conveniently studied by themselves. 

It had already been recognised by Lavoisier that all so-called organic 
compounds, originating in organised bodies, contain carbon, hydrogen, and 
oxygen, and that many of them, especially those of the animal kingdom, 
contain also nitrogen and sometimes sulphur, phosphorus, halogens, and 
metals. 

The study of organic compounds is as old as the human race, which, from 
the most remote times, has prepared alcohol and acetic acid from vegetable 
juices (the must of the grape and other fruit, &c.). 

After the discoveries of Lavoisier and the investigations of Berzelius, 
organic chemistry began to acquire a special importance. And Liebig, by 
introducing simple and exact methods for the analysis of organic compounds, 
rendered most valuable help to the wonderful theoretical and practical 
development which has been shown by this branch of chemistry during the 
past fifty years, and which has been largely responsible for the impulse given 
to progress and civilisation in the nineteenth century. 

In order to study the innumerable derivatives of carbon, to be able to obtain 
separate individuals and to characterise them by means of their chemical and 
physical properties, then to group and classify them and to deduce in a more 
or less general way the laws they obey, it was necessary to isolate and prepare 
in the pure state these separate chemical individuals. 

1 E. Molinari, "Inorganic Chemistry"; Translated by E. Feilmann, 1912. 



2 ANIC CHEMISTRY 




OF ORGANIC SUBSTANCES 

The purification of organic substances is not so easy to effect as might appear at first 
sight. Pure substances are characterised by certain physical constants (boiling-point, 
melting-point, crystalline form, &c.), which serve to show if a substance is in a suitable 
condition for chemical analysis. 

The chemical processes of purification may be deduced from the chemical properties 
of the substances themselves, as described in Parts II and III of this treatise ; general 
physical methods effect purification by means of suitable solvents (water, alcohol, ether, 
light petroleum, acetic acid, benzene, acetone, chloroform, carbon disulphide, &c.), which 
separate certain substances from others more or less soluble ; or, in many cases, purifica- 
tion is brought about by crystallisation, a solution of the impure substance in a suitable 
hot solvent depositing on gradual cooling or partial evaporation of the solvent the 
pure substance in characteristic and well-defined crystalline forms, which can be controlled 
by measuring the angles and determining the axial ratios of the crystals. 

Impurities separate sometimes before and sometimes after the 
crystallisation of the substance under examination, so that recourse 
is had to fractional crystallisation, which, when repeated, may give 
excellent results. 

In certain cases, substances are purified by sublimation. 1 When 
pure, a liquid has a constant boiling-point for a definite pressure 
(vol. i. p. 81), and this is determined by distilling the liquid in a 
flask with a lateral tube, a thermometer being arranged in the neck 
of the flask without its bulb dipping into the boiling liquid. The 
temperature of the vapour gives the boiling-point of the liquid ; the 
vapour escapes from the side -tube and is condensed by means of a 
Liebig's condenser, formed of an inclined glass tube surrounded by 
a wider tube through which water circulates from the lower to the 
upper end (Fig. 2^- 

The boiling-point of a very small quantity of substance can be accurately determined 
by means of the arrangement shown in Fig. 3 : a few drops of the liquid are introduced 
into a small tube, d, closed at the bottom and drawn out into a narrowed part. Into the 
liquid^dips a capillary tube, sealed at the point a by fusing the glass. The tube is attached 
to the thermometer, c, and the whole immersed, to the depth of a few centimetres, in a 
liquid having a boiling-point higher than that of the liquid under examination. Heat 
is now gradually applied, superheating being prevented by the air-bubbles issuing from 
the lower end of the capillary tube. When the boiling-point is reached, bubbles form 
very rapidly at the bottom of .the liquid, and the boiling-point is read off on the 
thermometer. 

Certain substances which readily decompose on boiling at the ordinary pressure can 
be distilled unchanged at a constant, but somewhat lower, temperature by lowering the 
pressure, i.e. by distilling in a vacuum (see later). For this purpose use is made of a 
mercury or water pump (Sprengel). 

When two liquids are mixed, they can be separated almost completely by fractional 
distillation, if there is a wide interval of temperature between their boiling-points. In 
consequence of the partial pressure of the components, at different temperatures mix- 
tures distil over which contain varying proportions of these components ; the liquid with 
the lower boiling-point first preponderates in the distillate, while at higher temperatures 
that with the higher boiling-point preponderates. On repeated redistillation of the two 
extreme fractions separately, the two liquids can be obtained in the pure state. In certain 
cases, however, a mixture of two liquids does not exhibit a regular progression in the 
vapour pressure corresponding with the preponderance of one or other of the two 
components. There are, indeed, liquids which, when mixed in certain proportions, show 
a minimum vapour pressure lower even than that of the less volatile component whilst, 

1 Sublimation takes place with many solid substances and consists in the passage from solid to vapour on gentle 
heating, and from the state of vapour to the solid crystalline condition wtjen the vapours come into contact with 
a cold body : these changes taking place directly and not by way of the liquid state. Usually the substance is 
placed on a clock-glass, covered by a perforated filter-paper and by a funnel ; on heating the clock-glass on a sand- 
bath, the pure sublimed crystals collect on the walls of the funnel (Pig. 1). In some cases, the sublimation is carried 
out in a vacuum. 



RECTIFICAT ION 



3 



on the other hand, a mixture of two liquids sometimes has a vapour pressure greater than 
that of its more volatile constituent ; the two liquids cannot then be separated by fractional 
distillation, especially when their boiling-points are not far apart. 1 In these cases good 
results are obtained practically by employing so-called rectification, this consisting in 
distilling the liquid mixture through a Le Bel and Henninger (1874) rectifying tube 



Tic 




FIG. 2. 



FIG. 3. 



(Fig. 4), which is fitted at regular intervals| with discs of 
platinum gauze, and above these takes the form of a series 
of two or more bulbs, a lateral tube being so placed as to 
lead the liquid condensing in any bulb back to the bulb 
below it. When the liquid boils, the mixed vapours pass 
up the tube and meet the first gauze disc, where the vapour 
of the less volatile liquid is condensed^in greater^ proportion 
than the other, so that the vapour reaching^ the second 
gauze is richer in that of the more volatile liquid ; a similar 
process occurs at the successive gauzes and in the bulbs 
above them, so that the vapour passing through the upper- 
most bulb is that of the more volatile liquid, and this passes 
down the side-tube (at the mouth of which the thermo- 
meter is placed) to the condenser. During this rectification 
the cooling produced by the outer air and the consequent 
condensation of the vapours result, in the rectifying tube, 
in a stream of liquid flowing down the walls of the tube ; 
this liquid meets the ascending vapours and gives up to 
them its more volatile constituent and takes up from them 
their less volatile component, so that only the vapour of 
the more volatile liquid reaches the top of the tube, while 
the less volatile liquid is returned. 

Similar results are obtained by Hempel's rectifying column (1881), which is filled with 
glass beads (Fig. 5). With this also the phenomenon of rectification which goes on often 

1 Theory of Fractional Distillation. We shall see later the relations existing between the boiling-point and the 
composition and chemical constitution of organic substances (homologous series, isomerides, &c.). Of interest 
at the present juncture is the behaviour on distillation of a mixture of two liquids which dissolve one in the other 
in all proportions. 

According to Wanklyn and Berthelot, when a mixture of equal weights of two liquids is distilled, the propor- 
tions of the two in the distillate depend not only on their proportions in the original liquid and on their vapour 
pressures at the boiling-point of the mixture itself, but also on the reciprocal adbesion of the constituent liquids 




FIG. 4. 



FIG. 5. 



4T- '. - ORGANIC CHEMISTRY 

permits of the separation of liquids with boiling-points quite close together. This 
phenomenon has important applications in the alcohol industry (see later), in the manu- 
facture of oxygen and nitrogen from liquid air, in the preparation of liquid sulphur dioxide 
(vol. i, pp. 245 and 295), and in many other industries. 




FIG. 6. 

In many cases substances (liquid or solid) are purified by distilling in a current of 
steam, certain of them being volatile under these conditions even when their boiling- 
points are above that of water ; in the distillate the substance often separates owing to 
its insolubility in water. An arrangement used in the laboratory is shown in Fig. 6, 
steam being generated in A and passing through the substance to be distilled in the 
flask, B, which can be heated directly with a flame. 

In some instances the distillation is 
effected by means of superheated steam (150- 
350), which is obtained by passing steam 
through a coil of iron or copper tubing 
heated with a bunsen burner (Fig. 7). 

A number of substances decompose when . . 
heated at the ordinary pressure, whilst they 





FIG. 7. 



FIG. 8. 



distil unchanged hi a more or less perfect vacuum, owing to a marked lowering of the 
boiling-point. Of the many different forms of apparatus employed in the laboratory for 

and on their vapour densities. When a mixture of two miscible liquids, in equal weights, is distilled, the quantity 
of each component which distils can (disregarding certain exceptions) be calculated by multiplying the vapour 
pressure (at the boiling-point of the mixture) by the vapour density. Hence it can be understood how, in some 
cases, the less volatile substance distils in greater quantity. Even if the vapours that distil over contain equal 
volumes of the two vapours (that is, equal numbers of molecules), the condensed liquid will contain a greater 
proportion by weight of the constituent with the higher molecular weight. This explains why water, with a low 
vapour density, causes substances with higher boiling-points (ethereal oils, naphthalene, &c.) to distil, since, 
although the latter have low vapour pressures, their molecular weights are high. 

On distilling a mixture of two liquids not soluble one in the other, the corresponding vapours do not influence 



MELTING-POINTS 



this purpose, that of Bredt is illustrated in Fig. 8. An ordinary thick-walled distilling 
flask, A, is used, its side-tube being connected with the condenser a and with the collecting 
apparatus, which consists of a flask, d, and three tubes, e, of thick glass, and is joined to 
the condenser by means of a perforated stopper ; the pump by which the air is withdrawn 
from the whole apparatus is connected with the tube, c, which communicates also with 
a manometer to show the extent of the vacuum attained. Superheating and consequent 
bumping of the liquid are avoided by the insertion of the tube b, the lower end of which 
is drawn out to a capillary and dips below the surface of the liquid, while the upper end 
is closed with a piece of rubber tubing fitted with a screw-clip ; by means of this tube, into 
which also the thermometer may be introduced, a slow current of air or other inert gas, 
controlled by means of the screw-clip, is allowed to bubble through the liquid. The 
flask is heated in a bath of oil or fusible alloy, and, if the distillate is very dense, no water 
need be passed through the condenser. The first portion distilling over at a definite 
temperature is collected in d, and when the temperature rises suddenly, the collecting 
apparatus is rotated so that the distillate is collected in one of the tubes, e ; when the 
thermometer no longer indicates 
a constant temperature, another 
of the tubes, e, is employed, and 
so on. 

MELTING-POINTS. Whilst 
with liquids the boiling-point is 
generally used as a criterion of 
purity, for solids the melting-point 
is mostly employed for this pur- 
pose, and in certain cases also 
the boiling-point. So long as the 
substance is impure, the melting- 
point is usually too low. The 
melting-point is determined by 
introducing a few centigrams of 
the substance into a very narrow, 
almost capillary glass tube closed 
at the bottom (Fig. 9), the tube 
being attached to the bulb of a 
thermometer dipping into a beaker 
of concentrated sulphuric acid, 
oil, or paraffin, which serves to 
transmit heat to the substance. A small glass stirrer serves to prevent superheating of 
the liquid, and, when the substance is pure, it melts entirely within a degree and generally 
becomes transparent. When the temperature of the bath approaches the melting-point 
the flame is lowered and the bath heated gently so that the temperature rises half a 
degree every four or five seconds ; only in exceptional cases should rapid heating be 
continued. 

To determine the melting-point of a fat, a tube drawn out to a capillary and sealed 
at the lower end (Fig. 10a) is held in an inclined position, and one or two drops of the fused 
and filtered fat introduced into the enlarged part (A, Fig. 10a). When the fat is solidified, 
the tube is kept in a cool place for twenty -four hours, after which it is attached vertically 
to the bulb of a thermometer ; it is then heated in a suitable bath, note being taken of 
the temperature at which (1) fusion begins, (2) the fat flows down and obstructs the 
capillary (Fig. 106), and (3) the completion of fusion is indicated by the entire liquefaction 
and transparency of the fat. 

one another, and the total pressure of the vapours is given by the sum of the pressures of the two liquids at the 
temperature of distillation. The boiling-point of the mixture is the temperature at which the sum of the vapour 
pressures of the components equals the atmospheric pressure ; it should be mentioned that the boiling-point of 
such a mixture is necessarily lower than that of the more volatile liquid, since here also Dalian's law of partial 
pressures (vol. i, pp. 71, 38.3, 491) holds. Naumann (1877) showed that, in the vapour distilling from such a mixture 
the ratio between the volumes of the components corresponds with the ratio between the vapour pressures of the 
two liquids at the boiling-point of the mixture ; and hence the weights of the two components are obtained by 
multiplying these ratios by the corresponding densities (or molecular weights). By means of this rule, Naumann 
succeeded in determining the molecular weights of various substances simply by distilling mixtures of them. A 
mixture of water and isoamyl alcohol (b.pt. 135) has a constant boiling-point of 96, and distils continuously 
in the ratio of two volumes of water and three volumes of the alcohol. 




6 



ORGANIC CHEMISTRY 



The melting-point of a fat can also be determined by drawing it in the fused condition 
into a capillary tube blown out at the middle into a bulb, which is half filled with the fat 
(Fig. 11) ; the upper end of the tube is kept closed with the finger until the fat becomes 
solid, the empty part of the tube being then bent round as shown and attached, upside 
down, to a thermometer, the whole being afterwards gradually heated in a beaker of water. 
When the fat begins to melt it flows into the lower part of the bulb (Fig. 11 A b, right-hand 
view), and when it is completely fused it becomes transparent. 

For fats and paraffins, or waxes in general, and for soft fats (for example, lubricants) 
especially, an important determination is that of the dropping -point, which is carried out, 

according to Ubbelohde's method (1905), by 
filling with the fat a glass capsule, e (Fig. 12, 
natural size), 10 mm. long and 7 mm. wide, 
with an orifice 3 mm. in diameter in the base ; 
a very small thermometer bulb is immersed in 
the fat and the capsule then affixed to the 
thermometer with a metal sheath having an 
aperature at c, and three points, d, which 
determine the position of the capsule ; the 
thermometer is then fixed in a test-tube 
4 cm. in diameter, dipping into a beaker of 
water, which is heated so that the temperature 
rises one degree per minute. At the orifice of 
the capsule a drop begins to form at a certain 
time, and when this falls the temperature is 
read, and is usually corrected by subtracting 
0-5 to obtain the real instead of the apparent 
dropping-point. 

This method has been adopted for the 
examination of lubricating oils supplied to the 
Italian navy and railways. 

The specific gravity of liquids also serves to determine their purity, and the various 
forms of apparatus used for measuring it are described in vol. i, p. 72. 





FIG. 11. 



FIG. 12. 



ANALYSIS OF ORGANIC SUBSTANCES 

As will be seen later, many so-called organic substances are composed 
of carbon and hydrogen combined in various proportions ; a large number of 
them also contain oxygen, while nitrogen is often present and sometimes 
sulphur, halogens, metalloids, and metals. 

Analysis of these compounds may be merely qualitative, when only a 
knowledge of the constituent elements is required, or it may be quantitative 
when the percentage amount of each of the elements present is determined. 

QUALITATIVE COMPOSITION. When organic substances are heated on platinum 
foil they either burn with a flame or leave a carbonaceous residue. The presence of 
carbon and hydrogen may be demonstrated by heating a little of the substance, mixed 
with cupric oxide, in a test-tube fitted with a delivery tube, the gas evolved being passed 
into a clear solution of barium hydroxide : if the latter becomes turbid, owing to the 
formation of barium carbonate, the presence of carbon is proved, and if drops of water 
condense in the cold upper part of the tube the substance must contain hydrogen. 

The presence of nitrogen can, in many cases, be shown by the smell of burning wool 
or nails developed when a little of the substance is heated on platinum foil. A more 
general and certain test is that devised by Lassaigne (1843) : 2-3 centigrams of the sub- 
stance are fused with a piece of metallic potassium or sodium (0-2-0-3 grm.) in a test-tube, 
which is broken by plunging it while still hot into a beaker containing 10-12 c.c. of water. 
The alkaline solution of potassium cyanide formed is filfered, mixed with a few drops of 
ferrous sulphate and ferric chloride solutions and boiled for two minutes, by which means 
potassium ferrous cyanide is formed (when nitrogen is present in the substance) ; the 
liquid is acidified with hydrochloric acid, which dissolves the ferrous and ferric oxides, 



ELEMENTARY ORGANIC ANALYSIS 7 

the resulting ferric chloride reacting with the potassium ferrocyanide to form the 
characteristic Prussian blue, or at least a green solution which deposits Prussian blue on 
standing. In absence of nitrogen, only a yellow colour is obtained. To certain nitrogenous 
substances this test is not applicable (e.g. to diazo -compounds, which evolve nitrogen too 
readily), and in such cases either the potassium is replaced by a mixture of potassium 
carbonate and powdered magnesium (Castellana, 1904), or the substance is fused with 
sodium peroxide and the mass tested for nitrate by means of diphenylamine (vol. i, p. 214). 

The presence of halogens (Cl, Br, I) is determined by heating the substance with pure 
lime, dissolving in water and nitric acid and precipitating the halogen with silver nitrate. 
Also, in many cases, the substance can be heated with fuming nitric acid and silver 
nitrate in a sealed tube (s -e later, Quantitative Analysis), by which means the silver 
halogen salt is formed dir ;ct1y (Carius). 

Sulphur also can be detected by the Carius method, the substance being heated in a 
sealed tube with fuming nitric acid and the sulphuric acid, formed from the sulphur of the 
organic compound, precipitated with barium chloride ; or by heating the substance with 
pure sodium peroxide, a sulphate is formed. By heating the substance in a test-tube 
with metallic sodium and dissolving the mass in a little water a solution of sodium sulphide 
is obtained which blackens a piece of silver foil or a silver coin. 

Phosphorus and other elements are detected by the Carius method, -the substance 
being oxidised with fuming nitric acid and the liquid tested for the corresponding acid 
(phosphoric, &c.) 

QUANTITATIVE COMPOSITION (ELEMENTARY ANALYSIS). Lavoisier first 
of all devised an apparatus for analysing organic substances by burning them with oxygen 

&> 6 d .# 9 

FIG. 13. 

a 5 cm. free ; b => 12 cm. spiral of oxidised copper gauze ; c = 8-10 cm. for the boat ; 
d 3 cm. copper spiral ; e = 40-45 cm. granulated cupric oxide ; / = 3 cm. oxidised copper 
spiral or 12 cm. of reduced copper spiral for nitrogenous substances ; g = 5 cm. free. 

under a bell-jar ; while Gay-Lussac, Thenard, and Berzelius successively improved this 
process by burning the substance in presence of potassium chlorate. Gay-Lussac, how- 
ever, showed that certain nitrogenous substances cannot be burned with the chlorate, and 
suggested as a general and more certain oxidising agent cupric oxide, which when hot 
gives up its oxygen, transforming the carbon and hydrogen of any organic compound into 
carbon dioxide and water respectively, while the nitrous compounds are reduced to free 
nitrogen by passing the products of combustion over red-hot copper turnings. But it is 
to Liebig that the credit is due of rendering this method of organic analysis simple and 
exact and of devising simple and ingenious forms of apparatus for absorbing the products 
of combustion. Even to-day disregarding improvements in combustion furnaces and 
modifications of the absorption apparatus the determination of carbon and hydrogen 
(the oxygen is estimated by difference) is carried out by what is virtually the method 
employed by Liebig. 

The method most commonly used is as follows : 0-15-0-30 grm. of the substance is 
weighed in a small porcelain boat, which is then filled with powdered cupric oxide, 
previously heated to redness and perfectly dry ; the boat is then introduced into the 
position c of the hard glass combustion tube (Fig. 13), this being 70-90 cm. long, or 
10-12 cm. longer than jthe combustion furnace,*, which is heated by 25-30 gas flames 
(Fig. 14). 

The other parts of the tube are reserved for the previously heated copper spirals and 
granulated cupric oxide (Fig. 13). When a fresh combustion is to be made, all that it 
is necessary to do is to remove the spiral b and the boat and to introduce the new substance 
into the tube, which is already charged in d, e, and / and is not allowed to cool below 
40-60. 

The combustion is carried out in the furnace shown in Fig. 14, the tube being closed 
at a with a good cork and a glass tap which can be connected at will with a gasometer 
containing air or one containing oxygen, which should, however, before reaching the 
combustion tube, pass through tubes containing potassium hydroxide to remove the 



8 . 

carbon dioxide, and then through drying tubes containing calcium chloride. At the 
other end the combustion tube communicates at b, first with a tared tube, c, containing 
granulated calcium chloride to absorb the water formed during combustion ; then 
follows the tared apparatus d, containing potassium hydroxide solution (30-35 per cent.), 
which absorbs the carbon dioxide from, the burnt substance and is furnished with a 
calcium chloride tube to retain the moisture given off by the potassium hydroxide solution. 
Finally follows a calcium chloride tube, e, which is not weighed; and prevents moisture 
entering the apparatus from the air. 

Before the combustion is started the apparatus is tested to ascertain if it is perfectly 
air-tight. This is done by closing the tap a, and sucking into e eight or ten bubbles of 
gas ; the slight rarefaction produced in the interior of the combustion tube causes the 
potash solution to rise in the first large bulb to a level which should remain constant for 
some minutes. The burners at the end b are then gradually lighted until the portion / 
and almost all of the portion e are heated to redness. The spiral b is then gradually heated 
from the a end, the heating being gradually extended under the boat so that the substance 
is completely burnt. During the combustion bubbles of air are passed into the tube 
from the gas-holder so as to transport the gases produced into the absorption apparatus ; 
during the last 10-15 minutes a gentle current of oxygen is passed through, and then the 
flames are extinguished and air again passed .for 10-15 minutes. In this way all the 
gases from the combustion are removed from the combustion apparatus and the copper 
oxide is completely reoxidised, so that the tube is ready for the next combustion. 




FIG. 14. 

The increases in the weights of the potash and calcium chloride apparatus give the 
amounts of carbon dioxide and water respectively formed during the combustion, and, 
since 44 parts of carbon dioxide correspond with 12 parts of carbon and 18 parts of water 
with 2*of hydrogen, the quantities or percentages of carbon and hydrogen in the substance 
can^be^calculated. The sum of these two percentages, when subtracted from 100, gives 
that of the oxygen, excepting where the substance, contains nitrogen, which is determined 
directly by methods given later. In this way the percentage composition is determined. 

For determining carbon and hydrogen in nitrogenous substances the above method is 
modified only by inserting in the combustion tube, in place of the spiral / (Fig. 13), one 
of reduced copper gauze x about 15 cm. long, this serving to fix the oxygen from the 
oxides of nitrogen resulting from the combustion and to liberate the nitrogen, which 
passes unchanged through the absorption apparatus. 

If the substance to be analysed contains sulphur or a halogen, the combustion is made 
with lead chromate in place of the granular copper oxide, and the heating is more gentle 
to avoid fusion of the chromate. By this means the sulphur remains fixed in the tube 
as lead sulphate and the halogens as halogen salts of lead. Halogens can also be fixed 
on a spiral of silver foil about 10 cm. long placed at / (Fig. 13), the substance being 
combusted as usual with cupric oxide ; if both nitrogen and a halogen are present the 
copper and silver spirals are used together. 

A new apparatus, which admits of the combustion of organic substances being very 
rapidly carried put, is that devised by Carrasco and Plancher (1904-1906). It consists of 

1 The reduction is effected in a separate glass tube, through which a current of hydrogen is passed while the 
spirals are heated ; when the copper has assumed its characteristic red colour, the flames are extinguished and the 
spirals allowed to cool in the current of hydrogen, being afterwards kept in desiccators ready for use ; or, better, 
when reduction is complete and the spirals are still hot, the tube is exhausted and is kept so until cold, so as to a void 
t,ho danger of hydrogen being occluded by the copper. 



RAPID ELEMENTARY ANALYSIS 



9 



a small external combustion tube, c (Fig. 15), of hard glass and about 20 cm. long and 
2 cm. wide and slightly expanded at the lower closed end. The tube is closed at the top 
by a rubber stopper, /, through which passes a porcelain tube, e, wound round with an 
electric resistance formed of platinum-iridium wire, d ; along the interior of the porcelain 
tubes passes a thick silver wire, which starts from d, the negative pole, and ends in a 
small platinum wire loop and serves to convey the current (3 amps, at 20 volts). The 
oxygen for the combustion traverses OS and the upright tube of the stand, and passes 
through the porcelain tube to the bottom of the combustion tube. In the stopper, /, is 
fastened a piece of nickel tube, &, which is united to the + pole and to the platinum 
spiral, d, and serves at the same time for the escape of the gases formed by the combustion 
to the tube r. The gases are absorbed by the usual tared apparatus (M=calcium chloride, 




FIG. 15. 

p= concentrated potassium hydroxide solution), but with nitrogenous or halogenatcd 
substances the gases are first passed through a U -tube containing lead dioxide heated to 
180 by means of a small furnace, TO. The connections a and b are insulated from one 
another by porcelain and rubber. When the current passes through the resistance the 
glass tube is heated to redness, and the substance (0-12-0-20 grm.), mixed with cupric 
oxide or, better, with platinised porous porcelain powder, and placed at the bottom of 
the glass tube, is burned by heating the outside of the tube directly with a Bunsen flame. 
The combustion is very soon completed, the platinum-iridium spiral apparently accelerating 
the oxidation catalytically ; apart from the time occupied by the weighings, this method 
requires 15-20 minutes, and usually gives good results. For the analysis of fairly 
volatile liquids or of substances which readily sublime, the lower part of the combustion 
tube is drawn out almost horizontally, and the substance is mixed with platinised porcelain 
powder (2-3 per cent, of platinum) ; liquids can be heated in a separate tube and the 
vapour then injected into the combustion tube. 

An electrical method for determining carbon, hydrogen, and sulphur in organic 
subtances was also proposed by Morse and Gray in America in 1906. 



10 



ORGANIC CHEMISTRY 




QUANTITATIVE DETERMINATION OF NITROGEN. (1) Dumas' Method. 
The nitrogenous organic substance (0-2-0-3 grm.) is heated in a hard glass tube similar 
to that shown in Fig. 1 3, but closed at the end, a. The portions a and 6 contain sodium 
hydrogen carbonate or magnesium carbonate ; between b and c is placed a small plug of 
copper gauze, in c granulated copper oxide, and in d powdered copper oxide. Then follows 
a space 10 cm. in length in which is placed the substance to be analysed, this being weighed 
and mixed with powdered cupric oxide ; next comes granulated cupric oxide, and in / 
a spiral of reduced copper, 10-12 cm. long. 1 

The extremity, g, of the tube is connected by means of a gas delivery tube with a 
graduated tube (25 or 50 c.c.), placed upside down in a basin of mercury and filled half 
with mercury and half with concentrated potassium hydroxide solution. This graduated 
tube may have the form devised by Dumas and shown in Fig. 16 ; the gas from the 
combustion tube passes into the tube a, furnished with a clip, m, 
thence through a little mercury in the bottom of the tube b, 
which is filled with potassium hydroxide solution and is in com- 
munication with a reservoir, c, of this solution. The operation 
is begun by heating the combustion tube at the point where 
the magnesium carbonate lies ; the carbon dioxide thus evolved 
expels the air from the apparatus into b, whence it is driven by 
raising the reservoir, c, and opening the cock at the top of b. 
The carbon dioxide is absorbed by the potash solution, and 
when no more air collects in 6 the magnesium carbonate is no 
longer heated. The copper spiral and the copper oxide are now 
gradually heated in the same way as for the estimation of carbon 
and hydrogen, the heating being slowly extended until it reaches 
the substance itself. Oxides of nitrogen are decomposed by the 
copper spiral, so that all the nitrogen is evolved in the free state 
and collects in b. Finally the nitrogen remaining in the com- 
bustion tube is driven into b by means of carbon dioxide formed 
by again heating the magnesium carbonate. 

At the end of the operation, in order to measure the nitrogen, 
a graduated tube filled with water is inverted over d, and the cock 
at the top of b having been opened, the reservoir, c, is raised until 
all the gas passes into the graduated tube. The latter can then 
be removed to a large cylinder full of water and when, after a 
few minutes, the gas has assumed the temperature of the water (shown by an accurate 
thermometer) the tube, grasped by a clip (the hand would warm it), is arranged so that 
the level of the liquid inside it coincides with that outside and the volume (v) of the gas 
read off. At the same time the atmospheric pressure (b) is read, and the exact tempera- 
ture (t) of the water. The percentage of nitrogen (p) in the substance is then calculated 
by means of the following formula : 

v. (b -w). 0-12511 
P = s.760(l + 0-00367-0 

where s indicates the weight of substance taken, w the pressure of water vapour expressed 
in mm. of mercury (see vol. i. p. 34) and 0-0012511 grm. the weight of 1 c.c. of moist 
nitrogen at and 760 mm. (Rayleigh and Ramsay). 

When several determinations of nitrogen are to be carried out the procedure is some- 
times simplified by using a combustion tube open at both ends, like that of Fig. 13, the 
magnesium carbonate or sodium bicarbonate being omitted and the combustion tube 
being connected at a with a small Kipp's apparatus for the evolution of carbon dioxide 
(marble and hydrochloric acid), care being taken to free the apparatus from all air by a 
prolonged current of carbon dioxide. 

|(2) KjelddhVs Method (Dyer's modification). 0-5-1 grm. of the substance is placed in 
a hard glass flask (200-300 c.c.) with a long neck, into which penetrates the stem of a funnel 
used to cover the flask (Fig. 17). 20 c.c. of concentrated sulphuric acid (66 Be.) and 

1 In this case the copper spiral can be rapidly reduced by heating it over a large non-luminous gas flame and 
dropping it into a thick-walled test-tube containing \ c.c. of ethyl or, better, methyl alcohol ; the tube is immediately 
closed by a rubber stopper through which passes a glass tube. The latter is connected with a pump until the spiral 
is cold. 




FIG. 16. 



ESTIMATION OF NITROGEN 



11 



a drop of mercury (which acts as a catalytic oxidising agent) are added, and the contents 
of the flask are heated, at first gently and finally more strongly, until vigorous boiling 
sets in. 10 grms. of potassium sulphate are then added, a little at a time, the heating 
being continued until the liquid is decolorised, by which time the whole of the nitrogen is 
transformed into ammonium sulphate. After the flask has been allowed to cool, its 
contents are washed out with water into a flask already containing 200-300 c.c. of water. 
3-4 grms. of zinc dust (which decomposes ammoniacal 
compounds of mercury and prevents bumping by the 
evolution of hydrogen) are then added, and the flask 
closed with a rubber stopper through which passes a 
tapped funnel containing 120-160 c.c. of concentrated 
sodium hydroxide solution (30-35 per cent.) and a glass 
bulb (Figs. 18 and 19) communicating with a simple 
condensing tube dipping into a flask containing a mea- 
sured volume of standard sulphuric acid and a drop of 
methyl orange. In order to prevent spurting of the 
caustic soda and its introduction into the condenser 
tube, the glass bulb is fitted with a delivery tube curved 
towards the wall of the bulb ; it is, however, as well 
to push into this tube, almost as far as the bulb, a small 
plug of glass-wool or asbestos. Solutions of soda more 
concentrated than 35 per cent, often lead to spurting. 
About one-half the liquid is distilled and the excess 
of sulphuric acid remaining in the collecting flask 
determined]by titration with alkali. Hence the amount of ammonia fixed by the acid can 
be'calculated and so the percentage of nitrogen in the substance analysed. In Figs. 17 and 
19 are shown forms of apparatus with which it is possible to carry out several determina- 
tions simultaneously. 




FIG. 17. 





FIG. 18. 



FIG. 19. 



Kjeldahl's method cannot be used for the analysis of organic substances which contain 
nitrogen either united to oxygen (nitro compounds) or forming part of a pyridine or similar 
nucleus (quinoline, &c.) 

(3) Will and Varrentrapp's Method. This method is based on the principle that 
almost all nitrogenous organic substances (which do not contain nitrogen linked to oxygen, 
such as the nitro-compounds), when they are heated with an alkali hydroxide or, better, 
with soda lime (see vol. i, p. 490), yield hydrogen, which transforms the nitrogen into 
ammonia. Little use is made of this method to-day. 

QUANTITATIVE DETERMINATION OF THE HALOGENS. The method most 
commonly used is that of Carius. The substance (0-15-0-2 grm.) is weighed out^in a 
small tube, which is then introduced into a large, hard glass tube 30-40 cm. long and 
2-3 cm. wide, closed at one end and containing about 2 c.c. of fuming nitric acid and about 
0-5 grm. of solid silver nitrate ; this introduction is effected in such a way that the acid 
does not enter the small tube. The large tube is then softened near the open end by heating 
in the blow-pipe flame andjjradually drawn out to a point, the walls of the tube being 



12 



allowed to thicken during the fusion (Fig. 20, B, shows the upper part of the tube on a 
larger scale). After being allowed to cool in a vertical position, the tube is introduced 
into a thick -walled iron sheath, which is closed with a screw-cap. It is then safe to incline 
the tube and introduce it into a bomb-furnace (Fig. 21), which holds four or more tubes 
and is raised slightly at one end ; this is heated for 4-6 hours, the temperature being 
raised gradually to about 250. Sometimes the tubes burst owing to the great internal 
pressure, but without danger from flying fragments of glass owing to the protection of 
the iron sheaths and of the folding shutters at the ends of the furnace, these being lowered 
during the heating. 

At the end of the operation, when the tube is cool, it is taken from the iron sheath, 
held in a vertical position and its point (Fig. 20, A a) softened in a Bunsen flame. When 
the pressure in the tube has been thus relieved, a scratch is made with a file at the point 
marked 6, and the file-mark touched with a red-hot glass, with the result that the upper 
part of the tube breaks off. The tube is then carefully emptied and washed out into a 
beaker with water, the small tube, held in pincers or a piece of platinum wire, being well 
washed inside and outside before removal. The liquid is heated and the precipitated silver 





FIG. 20. 



FIG. 21. 



halogen compound is then collected on a filter, washed, dried in an oven, detached from 
the filter and heated in a weighed porcelain crucible until it just begins to melt. After 
being allowed to cool in a desiccator, the crucible is weighed and the amount of halogen 
contained in the organic substance calculated from the weight of silver haloid. 

QUANTITATIVE DETERMINATION OF SULPHUR AND PHOSPHORUS. 
This is carried out by the Carius method in the same way as for halogens, except that 
no silver nitrate is introduced into the tube. At the end of the heating, the sulphur is 
obtained as sulphuric acid or the phosphorus as phosphoric acid, estimation of the amounts 
of these acids being effected by the ordinary methods. The halogens, sulphur and 
phosphorus, may also be determined after fusion of the substance with pure sodium 
peroxide. ' 



CALCULATION OF THE EMPIRICAL FORMULA. From the 
results of the elementary analysis of an organic substance can be calculated 
the percentage composition, i.e. the quantity of each component in 100 parts 
of substance. To deduce the chemical formula, that is, the proportions in 
which the different atoms enter into the molecule, the percentage weight of 
each component is divided by the corresponding atomic weight, the numbers 



MOLE. CULAR WEIGHTS 13 

thus obtained giving the proportions between the numbers of atoms of the 
different elements. 

These numbers sometimes give directly the numbers of atoms contained 
in the molecule, but in other cases they represent multiples or submultiples of 
the real numbers of atoms. 

If, for example, lactic acid is analysed, the percentage composition is found 
to be : C, 40 per cent. ; H, 6-6 per cent. ; 0, 53-4 per cent ; by dividing these 
numbers by the corresponding atomic weights, the following numbers are 
obtained: C, 3-3 (i.e. -*-); H, 6-6 (*-); and 0, 3-3 (^*-). These pro- 
portions have a common factor, 3-3, and division by this gives 1C, 2H, 
and 10, i.e. CH 2 O, which is an empirical minimum or formula, the simplest 
formula expressing the proportions between the numbers of atoms of the 
different elements. 

This minimum formula does not, however, represent the molecular magni- 
tude, and, in fact, analyses of formaldehyde, acetic acid, grape sugar, &c., 
give the same percentage composition and the same minimum formula, CH 2 0, 
which must hence be a submultiple of the formulae of these substances. 

^ knowledge of the percentage composition is not sufficient to determine 
the true molecular formula ; the molecular magnitude, i.e. the molecular 
weight, must also be known in order to permit of a choice between the various 
multiples. By making use of one of the methods described in vol. i, " Inorganic 
Chemistry " (pp. 39, 81 et seq.), the molecular weight of lactic acid is found to be 
90, so that, of the various possible formulae, CH 2 (mol. wt. 30), C 2 H 4 2 

(mol. wt. 60), C 3 H 6 3 (mol. wt. 90), C 4 H 8 4 (mol. wt. 120) C 6 H 12 6 

(mol. wt. 180), &c., only C 3 H 6 3 corresponds with lactic acid. But even 
this formula and the empirical formula tell nothing concerning the grouping 
of the atoms in the molecule which, as is explained in the following pages, is 
given by the constitutional formula. 

DETERMINATION OF THE MOLECULAR WEIGHT BY 
CHEMICAL MEANS 

In lactic acid one-sixth of the hydrogen can be substituted by a metal, so that there 
must be at least six (or a multiple of six) atoms of hydrogen in the acid, the empirical 
formula being necessarily at least trebled, giving C 3 H 6 3 . To ascertain if this is the true 
formula, a derivative of the acid is prepared, such as the silver salt, which can easily be 
obtained pure. Analysis of this salt shows it to contain 54-8 per cent, of silver, and the 
atomic weight of silver being 107-7,. calculation indicates that the residue of the lactic 
acid combined with 107-7 parts of silver weighs 89. Assuming that only 1 atom of silver 
has entered the lactic acid in place of 1 of hydrogen (as can, indeed, be deduced from the 
fact that the quantity of hydrogen in the salt is five -sixths of that originally present in 
the acid), the weight of the lactic acid would be 89 + 1, or 90. The true formula of the 
acid would hence be that. corresponding with a molecular weight of 90, i.e. C 3 H 6 O 3 . 

For acid substances in general this chemical method may be employed for determining 
the molecular weight, making use of the silver salt and determining if the acid is mono-, 
di-, or tri-basic (that is, ascertaining if the silver replaces 1, 2, or 3 atoms of hydrogen), 
the calculation being then based on the presence of 1, 2, or 3 atoms of silver in the salt. 

For basic substances, the molecular magnitude may be determined chemically by 
analysing the platinichlorides, the formulae for which are always of the type of that of 
ammonium platinichloride : PtCl^NHg-HCl^, the ammonia being replaced by the organic 
base, which is mono- or di-acid, according as it replaces one or two molecules of ammonia 
in the platinichloride. 

For other (indifferent) organic substances derivatives are prepared by substituting 
chlorine atoms for one or more hydrogen atoms, the proportion of chlorine being then 
estimated ; the calculation is then similar to that described above. 

The chemical method for determining the molecular magnitude does not always give 
certain results : experimental difficulties sometimes occur and often entail great labour. 



14 ORGANIC CHEMISTRY 

Consequently the determination of molecular weights is usually effected by physical 
methods : vapour density method, cryoscopic method, ebullioscopic method, &c., these 
being all described and illustrated in vol. i (Part I). 

POLYMERISM 

It sometimes happens that the analysis of different substances shows them 
to have the same percentage composition, although their chemical and physical 
properties are different ; thus, for example, acetic acid, lactic acid, glucose, &c., 
contain the same elements, C, H, and 0, in the same proportions, there being 
2n hydrogen atoms and n oxygen atoms for every n carbon atom. Accurate 
study of these compounds and determination of the molecular magnitude 
(molecular weight) shows that the differences depend on the true formulae 
being multiples of the minimum or empirical formula. Thus, whilst the 
molecule of acetic acid is represented by C 2 H 4 2 , that of lactic acid corre- 
sponds with C 3 H 6 3 , and that of glucose with C 6 H 12 6 . These molecules are 
hence all multiples of a hypothetical complex CH 2 0, the ratios (but not the 
absolute quantities) between carbon, hydrogen, and oxygen being the same 
(1:2:1) in all cases. These compounds are termed polymerides and the 
phenomenon is known as polymerism. 

In some instances, however, it happens that the molecular magnitude is 
not sufficient to differentiate certain compounds, which, besides containing the 
same elements in the same proportions (equal percentage compositions), have 
also the same molecular magnitudes, although differing in their physical and 
chemical properties. To explain the existence of these isomeric compounds, 
the chemical nature of carbon must be studied more in detail. 



VALENCY OF CARBON, ISOMERISM, AND 
CONSTITUTIONAL FORMULA 

On the foundation of multivalent radicles, 1 discovered by Odling, and of 
the investigations of Frankland (1852), which showed that nitrogen, phos- 
phorus, and other elements easily formed compounds with three or five 
equivalents of other elements, Kekule, in 1857 and 1858, accurately developed 
the true conception of valency, showing the constant tetravalency of carbon 
and thus widening the horizon of organic chemistry and originating the 
remarkable theoretical and practical development of the past half -century. 

1 Theory of Radicles and Types. In the first twenty years of last century, various compounds were 
discovered which stood in apparent contradiction to the electro-chemical theory of dualistic formulae, put 
forward by Berzelius (vol. i. p. 44) ; in fact, in certain compounds, the hydrogen (electro-positive) was replaced by 
chlorine (electro-negative) without appreciably changing the chemical characters of the original compounds. It 
was then that chemical combinations came to be represented by unitary formulae, no account being taken of the 
grouping of the atoms in the molecule. 

But gradually, as the number of new organic substances increased, certain analogies became evident in their 
chemical behaviour. In studying cyanogen Gay-Lussac (1815) had indeed met, in various reactions and in various 
substances, the residue or radicle CN, which behaved as a monovalent element (like the halogens), combining with 
one atom of different monovalent metals, &c. In 1832 Liebig and Wohler discovered and studied a monovalent 
atomic group or radicle, benzoyl, C,H 6 O, which was found in oil of bitter almonds combined with an atom of 
hydrogen (C 7 H,O) ; on oxidation by the air, this essence became transformed into benzoic acid, C,H 6 O 2 , which 
with PC1 5 gave benzoyl chloride, C 7 H 6 OC1, and this, in its turn, gave the aldehyde C 7 H 6 O, when treated with 
nascent hydrogen, or benzoic acid under the action of water. All these compounds contain the monovalent 
benzoyl nucleus, C 7 H 5 O, which passes unchanged from one to the other by combining with monovalent atoms or 
groups. In 1833, in a classic work, Bunseu studied another radicle, cacodyl, which is a monovalent organic arsenic 

residue, As<C^pTT*. Later, in 1837, Dumas advanced and developed the theory of radicles, studying and classifying 

organic compounds with reference to the different radicles contained in them, these radicles thus coming to be 
considered almost as the elementary substances of organic chemistry. The condensation of simple radicles then leads 
to a compound radicle, forming a complex which can unite with other atoms or atomic groups. Liebig supported 
this new theory, whilst Berzelius strenuously opposed it, reproaching Dumas for regarding all chemical combinations 
as due to reciprocal interchanges of radicles. 

Dumas and, still more so, Laurent, as a consequence of the discovery of new substances, arrived logically at 
the theory of substitution, which admits the possibility of replacing, one by one, the elements forming the radicle or 



RADICLES: SUBSTITUTION 15 

Kekule and, independently of him, Cooper brought to light another most 
important property of carbon, resulting from its four equivalent valencies ; 
they showed that carbon atoms possess also the property of combining directly 
one with another, in a greater or less number, mutually saturating one, two, 
or even three valencies and forming varying chemical compounds. For 
convenience, we represent these compounds graphically, placing the carbon 
atoms in an open or closed chain and saturating the valencies remaining free 
with other elements (usually hydrogen and oxygen). We have thus a series 
of groups differing according as the atoms united in a chain are few or many 
(even more than 30), according to whether the chain is branched by means 
of lateral chains, and also according as the valencies saturated between carbon 
and carbon are 1, 2, or 3. 

If we represent the valencies of carbon by strokes, the valencies of the different carbon 

nucleus of certain compounds by other elements or by radicles of other compounds (Dumas termed this phenomenon 
of substitution metalepsy). 

Not only the hydrogen and oxygen but also the carbon of the radicles could, according to Laurent, be replaced 
by other radicles or other elements, e.g. by chlorine, without the fundamental characters of the original substances 
being substantially changed. 

These last consequences of the theory of substitution in radicles (Dumas) or in nuclei (Laurent) were combated 
not only by Berzelius, but even by Liebig, who attempted to cover these new conceptions with ridicule and pub- 
lished in his " Annalen " (1840) a pungent satire in the form of a letter from Paris which was signed " S. C. H. 
Windier " (Schwindler being the German for swindler I), and which made the astonishing statement that it had 
been found possible to replace all the atoms of the molecule of manganese acetate by the corresponding number 
of chlorine atoms, the resulting substance retaining the characters of the original salt, although formed of chlorine 
alone ; further, on the basis of the new theory, it was concluded that the chlorine used in England to bleach 
textiles replaced the hydrogen, oxygen, and carbon, and that already chlorine was being spun for the manufacture 
of nightcaps, which were greatly appreciated ! ! 

Nevertheless, the new conceptions triumphed with the aid of numerous discoveries, which served to confirm, 
more and more, the ideas of Laurent and Dumas And with the studies of Gerhardt, new horizons were opened to 
organic chemistry, which for so many years found a solid bo.sis in Laurent and Gerhardt's (1852) theory of types, 
these clearing up the nebulous i4eas then still held on the atom and the molecule ; and it is due to these two 
investigators that Avogadro's work, denied by everybody, finally assumed the important position accorded to it 
in modern chemistry. 

All organic and inorganic compounds were explained by comparing them with simple types of inorganic sub- 

TT \ TT "1 

stances of well-known constitutions. The fundamental types of Gerhardt were four in number: [-, fjr 

N SJ {jlJ 



It was supposed that all the principal chemical compounds then known were derived from these types by 
simple substitution of the hydrogen by other elements and radicles. Fro in the first type can be derived, for 

ON" I ft TT "i ft TT ~\ 

example : hydrocyanic acid, - ( , ethane, * T ? f, ethyl cyanide, L.J f, &c. ; from the second, sodium chloride, 
n.) H) UJN } 

Na 1 CHI CHOl 

*C1 / ' e( "'kyl chloride. 2 _? j- , acetyl chloride, 2 3 | , and so on. With the third type correspond, for example, 

sodium hydroxide, JJ r O, nitric acid, ,J f O, acetic acid, ' 2 * J- O, nitric anhydride, XTr . 2 \ O, acetic anhydride, 

tlJ Jtt J J J JMUj-' 

C 2 H S I Q &c 

From the fourth type, Hofmann and Wurtz deduced theoretically and prepared in the laboratory a large number 
of compounds, part or all of the hydrogen atoms of ammonia being replaced ; for example, ethylamine H j-N, 

dicthylamine, C 2 H 6 ]-N, trimethylamine, CH 3 J-N, acetamide, H \~S, &c. 

Hj CH 3 J Hj 

To explain the existence of polybasic acids and various other substances, Odling, Williamson, and Kckul6 

51 H IO 

had recourse to multiple types, sulphuric acid being regarded at. derived from the double water type SO 2 [ , 

H) , 

and similarly succinic acid CjHjOj f , &c. ; for glycerol, a triple type was assumed, and so on. 
H' U 

H 
In 1856 Kekule introduced another very important type, that of marsh gas, VC, with tetravalent carbon, 



to which he referred numerous organic compounds ; also certain compounds can be referred both to marsh gaa 



PTT -v 
8 



H 



and to ammonia, for example, methylamine, H [-N, or f; VC, and from these different methods of considering 



the constitution and the reference to different types, were deduced various processes for preparing one and the 
same compound from different starting materials 



16 



ORGANIC CHEMISTRY 



atom chains are given by the number of free valencies which are not used in uniting the 
carbon atoms among themselves and which can be saturated by different elements 
(usually H, O, N), giving rise to an enormous number of organic compounds. 
The following are some of these hypothetical carbon atom chains : 



(1) 



C/ C 

(2) II >; (3) HI 



c 



Hexavalent Tetravalent Divalent 



HI ; (4) C=; (5) C ; (6) C ; (7) C ; 

c- \/ \/ \/ \ / 

fir P P r 1 / 

\ C \ \ \ 



(8) 



(9) C Of- , &c. 



(10) 



/ c \ 

C C 

(11) II I 

f"1 f-\ 



V 



(12) 



_ P __ pi _ 

|| II ; 

C C 



(13) 



>c 
>c 



C C 



(14) 



C C 



A 



c 



(15) 



- c x 
c c- 

II I 

C C 



Among these chains are two (Nos. 8 and 9) containing four carbon atoms and having 
equal numbers of free valencies. By saturating these ten free valencies with ten H atoms 
two compounds are obtained (these have actually been prepared) which contain equal 
numbers of C and H atoms, and have therefore the same percentage composition and the 
same molecular weight. 

The physical and chemical differences of these two compounds, termed 
isomerides, are explained by the different grouping or linking of the atoms 
in the molecule. In their chemical transformations, isomerides give up or 
exchange quite different atomic groups or atoms, owing to the different functions 
and positions occupied by these atoms or groups in the molecule. 

It is hence not sufficient to represent organic compounds by an empirical 
molecular formula, the structural or constitutional formula, deducible 
from the graphic representation of the chains illustrated above, being necessary 
in many cases to distinguish between isomerides. 

To decide which of two isomeric formulae should be assigned to a given 
substance, various chemical reactions are carried out with the substance, 
study of the new products indicating the constitutional formula. 

An example will render these ideas clear : It is found that ethyl alcohol (ordinary 
liquid alcohol) and gaseous methyl ether have different physical and chemical properties, 
although they possess the same percentage composition and the same molecular magnitude, 
represented by the formula C 2 H 6 0. The constitutions or internal molecular structures 
of the two compounds are determined by a study of the following chemical reactions : 
treatment of the alcohol with hydrochloric acid gives first a compound C 2 H 6 C1 (ethyl 
chloride), one atom of monovalent chlorine having replaced one atom of oxygen and one 
of hydrogen or a hydroxyl residue, OH. By means of nascent hydrogen, the chlorine 
atom of ethyl chloride can be replaced by a hydrogen atom, giving the compound 
C 2 H 6 (ethane). These reactions are hence expressed by the following equations : 



CHEMICAL CONSTITUTION 17 

(1) C 2 H 6 .OH + HC1 = H 2 + C 2 H 5 C1 ; (2) C 2 H 5 C1 + H 2 = HC1 + C 2 H 6 ; but ethane 

H \ / H 

can have only the constitution, H-^C C~ H, i.e. CH 3 CH 3 , so that the alcohol will 

H/ \H 

Hv ,OH 

have the constitution H-^C 0^ H 
H/ \E 

On the other hand, it is found, by various reactions, that the six hydrogen atoms of 
methyl ether present no difference one from another, and, no matter under what conditions 
hydriodic acid acts on the ether, it eliminates the oxygen as water, and another product 
is obtained which contains only one carbon atom in the molecule : The reaction hence takes 
place according to the equation : 

G 2 H 6 + 2HI = 2CH 3 I + 



It is evident, then, that in methyl ether the six hydrogen atoms are united homo- 
geneously to the two atoms of carbon and that the carbon atoms are joined, not directly, 
but indirectly, by means of an oxygen atom, which is readily eliminated. The constitu- 
tional formula of methyl ether will hence be : 

H 



H-)C OH or CH 3 O CH 3 . 
H/ \H 

Use is not always made of constitutional formulae, since they are not 
simple and are often inconvenient to write ; hence attempts are made to 
simplify them by indicating the more important groups or residues contained 
in the molecule and giving at the same time an idea of the constitutions and 
of the functions of these groups ; this is done by means of the so-called rational 
formulce. The rational formula of ethyl alcohol will be C 2 H 5 *OH, in which 
the monovalent OH residue, characteristic of all the alcohols, is separated ; 
that of acetic acid will be CH 3 'COOH, the group COOH being characteristic 
of and common to all organic acids, &c. 

METAMERISM. Constitutional and rational formulae explain clearly 
isomerism in general and also the special case bearing the name metamerism. 
When, to an atom of a polyvalent element are united one or more groups in 
their different isomeric forms, we have special cases of isomerism for definite 
groups of substances. 

xC 3 H 7 

For example, in the compound, N^-H , the monovalent group C 3 H 7 may be 

\H 

xCH 3 
present in its isomeric forms, i.e, either as CH 2 CH 2 CH 3 or as C^-H . Although 



there is considerable resemblance between these two compounds, their different con- 
stitutions are manifested in certain chemical and physical properties. The following 

xCH 3 /CH 3 

compounds are also metameric isomerides : N^-GyB* and N^-CH 3 ; in fact, although the 



percentage compositions and molecular magnitudes are the same in both cases, the sub- 
stituent groups of the ammonia molecule are different and the compounds belong to 
different categories disubstituted and trisubstituted ammonias. 

PSEUDOISOMERISM, TAUTOMERISM, DESMOTROPY. A sub- 
stance sometimes contains atomic groups that occupy a very precarious 
(labile) position, since they exert certain influences one on the other and under 
certain given conditions can react in different ways, giving now one new 
substance and now another ; this explains how it is that some compounds 
having a well-defined chemical character can, under some conditions, behave 
like substances with other chemical characters, without it being necessary to 

II 2 



18 

assume a true change of constitution. Thus, for example, some of the deriva- 
tives of cyanic acid, CN OH, behave like derivatives, sometimes of the formula 
N=C OH and sometimes of the formula NH = C = O, when the hydrogen 
atom is replaced by a given radicle. The same is the case' for derivatives of 
cyanamide, N^?C NH 2 , and of carbodiimide, NH = C=NH ; and of the 

two non-nitrogenous types, C(OH) = C CO and CO CH CO, where 
a hydrogen atom oscillates between, the two carbon atoms. These compounds 
exist usually in only one form, the more stable one, but in the derivatives 
this stable form, simply on heating, is transformed into the labile one. For 
this phenomenon Baeyer proposed the name pseudoisomerism, and others 
that of desmotropy. 

These forms can be distinguished sometimes by chemical reactions, but 
more generally by the molecular refraction, dielectric constant, magnetic 
rotation, electrical conductivity, &c. 

In various substances, where several hydroxyls are present in more or less 
adjacent positions, there is often a tendency for intramolecular transformation 
to take place with condensation of two of these groups and separation of a 
molecule of water, giving rise to isomeric anhydrides, ethers, ketones, or 
alcohols, &c. In their turn, these derivatives or isomerides, which can be 
transformed one into the other, give rise to distinct classes of compounds, 
and this species of isomerism is called tautomerism. 

STEREOISOMERISM OR ISOMERISM IN SPACE. We have already seen that, 
by the tetra valency of carbon and its property of uniting with itself to form various chains, 
it is possible, in certain cases, to explain the existence of isomerides, which have the same 
percentage composition and molecular magnitude, but different groupings within the 
molecules. Many cases of isomerism, foreseen from theoretical considerations, have 
since been actually met with and different isomerides have been prepared artificially 
after their existence had been foretold. 

For a long time, however, certain compounds were known for which ordinary isomerism 
did not provide any explanation j among these the most important, from an historical 
point of view also, are the four dihydroxysuccinic acids (tartaric acids), of which two 
(ordinary tartaric acid and racemic acid) were studied by Berzelius as long ago as 1830. 
To these must be added laevo -rotatory tartaric acid and meso tartaric acid discovered by 
Pasteur. All these compounds have the same internal grouping of the atoms, although 
they are isomerides ; it is not possible to distinguish between them by chemical reactions, 
but they can be clearly differentiated by their physical behaviour : they form hemihedral, 
i.e. symmetrical, but non-superposable crystals (related as an object to its image in a 
mirror) : they have, too, different actions on polarised light, the plane of which is turned 
to the right by some and to the left by others. These acids are hence known as physical 
or optical isomerides. 

Pasteur attempted to explain this isomerism by supposing the atomic groups to be 
arranged unsymmetrically in the molecule, in some cases in a dextro-rotatory spiral 
and in others in a laevo -rotatory spiral, or arranged at the vertices of an irregular tetra- 
hedron. 

When other similar isomerides the lactic acids had been discovered, J. Wislicenus, 
in 1873, suggested that isomerism of this kind could be explained only by regarding the 
groups or atoms of these compounds as arranged in space so as to form distinct configurations. 

This isomerism in space (stereoisomerism) was explained by van 't Hoff and Le Bel 
(1874), independently, by means of the hypothesis of the asymmetric carbon atom. The 
starting-point of this hypothesis was Kekule's idea (1867) of regarding, for the sake of 
convenience, the carbon atom as situated at the centre of a regular tetrahedron, and its 
four affinities as directed towards the four vertices, i.e. arranged homogeneously in space 
(Figs. 22, 23). If these affinities are satisfied at the vertices by monovalent atoms or 
atomic groups, the following cases present themselves : no isomerism is possible in the com- 
pounds Ca 3 b, Ca z b z , Ca z be, and Ca b z c, where a, b, and c indicate either atoms other than 
carbon or groups of atoms (I, H, OH, &c.) ; the compound CH 2 I 2 exists in only one form, 
and if we put the four atoms (H 2 and I 2 ) at tiie apices of the carbon tetrahedion, no matter 



STEREOISOMERISM 



19 



how their positions may be changed, it is not possible to find two different, i.e. non-super - 
posable arrangements. If, however, the four groups or atoms combined with the carbon 
atom are all different, e.g. Cabcd, two isomerides are possible and in this case the carbon 
atom is termed asymmetric; in fact, if these atoms or groups are arranged, in one case, 
so that the circle a, b, c has a sense opposite to that in which the hands of a clock move 
(Fig. 24, I) (called, therefore, dextro-rotatory isomerides, and indicated by d- or by the 
8tgn +) and, in the other, in the opposite sense (Fig. 25 II) (termed Icevo-rotatory isomerides, 
like levulose and indicated by I- or ), two non-congruent configurations are obtained ; 
these cannot be superposed, one on the other, so that the same groups occupy the same 




positions in the two cases. These two figures represent two different isomerides and 
are related in the same way as an object to its mirror-image or as the left hand to the 
right. This isomerism is called enantiomorphism. 

These two different arrangements of the atoms round the asymmetric carbon atom 
also explain how it is that when polarised light traverses these molecules, its plane 
of polarisation is rotated, in one case to the right and in the other to the left. Van 't 
Hoff and Le Bel pushed their deductions still further, and showed that the dextro-optical 
deviation should be numerically equal to the laevo -optical deviation of the corresponding 
isomeride. This has been confirmed practically, and it also follows that when a pair of 
such isomerides are mixed in equal proportions, there should result an optically neutral 
mixture, thus giving rise to a special inactive or racemic isomeride. A substance with 
only one asymmetric carbon atom always gives three stereoisomerides (for example, three 
lactic acids). 

It has also been deduced theoretically and proved practically that all optically active 
compounds contain at least one asymmetric carbon atom, 1 although not all compounds 
containing asymmetric carbon atoms are optically active, since the molecules may contain 
groups which neutralise each other's activity. 

Many examples illustrating these principles will be discussed later in the special part 
of this book ; meanwhile mention may be made of the most important of these com- 







FIG. 27. 



FIG. 28. 



pounds : leucine, asparagine, coniine, the lactic acids (hydroxypropionic acids), &c., which 
contain one asymmetric carbon atom and give, in each case, three stereoisomerides. 

These cases of stereoisomerism, and those which follow, will be understood more 
easily if studied by means of cardboard tetrahedra with differently coloured vertices. 

When the substance contains two asymmetric carbon atoms, the number of stereo- 
isomerides increases as follows : 

If we take two tetrahedra like that shown in Fig. 26 I and Fig. 28 II, representing 
two similar molecules containing only one asymmetric carbon atom in which the groups 

1 Or else an asymmetric atom of nitrogen (see later) or sulphur, tin, &c. The exceptions to this rule are very 
rare and uncertain, one of the cases most discussed during recent times (1909-1910) being \-methylcyclohexylidene- 
1-acetic acid, which does not appear to contain an asymmetric carbon atom, but is optically active. 



20 



ORGANIC CHEMISTRY 



a, 6, and c, satisfying three of the^ valencies, are arranged in a dextro-rotatory sense, and 
superpose one tetrahedron on the other, so that the free valencies satisfy one another, 
there results a new isomeride, i.e. a molecule with two dextro-rotatory asymmetric carbon 
atoms, as shown in Figs. 27 and 29. 1 

If we join two Isevorotatory carbon atoms (Fig. 28 II), that is, the mirror images 
of Fig. 26 I, a laevo -rotatory isomeride (Fig. 30 II) is obtained. 

Finally, if one dextro-rotatory (Fig. 26 I) and one Isevo -rotatory asymmetric carbon 
atom (Fig. 28 II) are united, a third stereoisomeride is obtained, which is permanently 
optically inactive (Fig. 31 III), the effect produced on polarised light by one asymmetric 
carbon atom being destroyed by the effect of the other. 





FIG. 29. 



FIG. 30. 




In order to understand these stereochemical speculations better, we will apply them 
to the isomerism of tartaric acid, which has the formula C 4 H 6 6 , and contains two asym- 
metric carbon atoms (marked with asterisks) to which are joined the groups OH, C0 2 H, 
andH: 

CO 2 H 



CO 2 H 

If, for the letters a, 6, and c of the tetrahedra considered above, we substitute the 
groups OH, C0 2 H, and H, and if the tetrahedron of Fig. 26 I (which we will call + A) 

be represented as if projected on to a plane, thus: a C c or OH C H (dextro- 

\1 \ I 

6 X C0 2 H 

I I 

rotatory), and that of Fig. 28 II ( A), thus : c C a or H C OH (Isevo -rotatory), 

I/ I / 

6 C0 2 H 

we arrive at the following stereoisomerides of tartaric acid : 

I. By joining two + A atoms, we get d-tartaric acid (Fig. 29 or 32 I). 

II. By joining two - A atoms, we get Z-tartaric acid (Fig. 30 or 32 II). 

III. By joining one + A atom with one A atom, we have the permanently inactive 
mesotartaric acid (t-tartaric acid), as can be seen in Fig. 31 III, or 32 III. 

IV. By mixing, mechanically, equal parts of acid I ( + ) and II ( - ), there results 
racemic acid, apparently inactive, but from which, by mechanical means (by hand with 
the aid of a lens), the two forms of crystals can be separated. 

It is often assumed that the two asymmetric carbon atoms can rotate independently, 
on the common axis joining them, so that if the groups of one asymmetric carbon atom 
exert an attraction or influence on those of the other, a most favourable position could 
be attained, a chemical reaction being sometimes possible between one group and another 

1 Looking at the order in which the letters a, b, and c come in the two asymmetric carbon atoms, it would seem 
that these are not dextro-rotatory, but this is because the upper carbon atom has been turned through ISO" from 
its position m Fig. 26 , if itn base is brought down, its identity with the other dextro-rotatory atom becomes 
evident. 



ALLOISOMERISM 



21 



with separation of, say, water and loss of the freedom of rotation ; to the new isomerism 
thus created we shall refer shortly. 

STEREOISOMERISM IN DERIVATIVES WITH DOUBLY LINKED CARBON 
(ALLOISOMERISM). By means of the tetrahedra, we can show a double linking between 
two carbon atoms by arranging one side of one tetrahedron (carbon atom) in][contact 
with a side of the other (Fig. 33). 

With such an arrangement, even without asymmetric carbon atoms, isomerism is 

possible. In fact, a compound />C=C<\ forms the following isomerides : (1) that 




CO,H 

CO,H CT>,H 

H-'C-OH HO-*C_H 

BO-'C-B H-'C.OH 

co,n CO,H 

I II 

FIG. 32. 



CO,H 
H-'C-OH 
H-'C-OH 

CO,H 

III 




FIG. 33. 





shown in Fig. 34, where the two similar atoms or groups of atoms, e.g. a and a, although. 

a C b 
united to two different carbon atoms, occupy adjacent positions : || , or ci's-posi'tions 

aCb 

(cis-isomerism) ; such a molecule exhibits plane-symmetry, the two pairs of similar groups 
lying to the left and right, respectively, of the perpendicular plane containing the common 
side (double linking) ; (2) that shown in Fig. 35, where two similar groups occupy non- 

a C 6 
adjacent or diagonally opposite or trans-positions , this form exhibiting centro- 

bCa 



Similarly, a compound of the type, ^>C=C<%, forms two isomerides, the cis-form, 

aCb aCb 

, and the trans-torm, 
a C c c C a 




_ HC C0 2 H 
~ HC.CO.jH 




__ HO,C.CH 

HO.C0 2 H 




FIG. 36. 



FIG. 37. 



FIG. 38. 



The best illustration of this type of isomerism is afforded by the two isomerides : 
maleic acid (cis-form, Fig. 36) and fumaric acid (trans-iorm, Fig. 37). 

From these figures it is seen that the cis-form, maleic acid, should lend itself to the 
ready formation of anhydrides (condensation of two molecules or acid groups with separa- 
tion of one molecule of water), since the two acid groups, CO 2 H, are very near to one 
another, and it is, indeed, found that maleic acid easily gives an anhydride with separation 
of one molecule of water (Fig. 38), whilst no anhydride of fumaric acid is known. 

Isomerism of this kind is exhibited by various substances, e.g. crotonic and isocrotonic 
acids (CH 3 CH : CH COOH); metacommand citraconic acids [CH 3 C(COOH ) : CH COOH], 
&c. 

Baeyer found that cases of isomerism similar to those just described occur also with 
cyclic compounds (see Part III), i.e. closed-chain compounds with simple linkings between 





22 ORGANIC CHEMISTRY 

the carbon atoms. He distinguishes with the sign T compounds containing true asym- 
metric carbon (absolute asymmetry), adding the sign + or if the compound is optically 
active ; while he gives the name relative asymmetry to that shown by compounds with 
doubly linked carbon atoms (alloisomerism) or by cyclic compounds with simple linkings, 
the term cis or trans being added to the JP. Thus, to the name tartaric acid would be 
added the sign F + or T according as the acid is dextro- or Isevo -rotatory, and to 
the name maleic acid _T cis , to fumaric acid J 7 " 3 " 5 , &c. 

STEREOISOMERISM OF NITROGEN. Le Bel attempted to explain the isomerism 
of certain nitrogen compounds (e.g. methyl-ethyl-propyl-isobutyl-ammonium chloride) 
by assuming absolute asymmetry for the nitrogen atom. A more plausible explanation 
seems, however, to be afforded by the idea of relative asymmetry of the nitrogen, analogous 
to that of carbon atoms when united by double linking ; in this way V. Meyer, Hantzsch, 
Werner, and others easily explained the isomerism of the oximes, hydroxamic acids, 

Cab 
phenylhydrazones, &c. In general, a substance of the constitution || should give two 

Nc 
isomerides which can be represented as shown in Fig. 39 ; the s^n-series (Fig. 39 I) and 

the anti-series (Fig. 39 II). 
*. ^^^^ These investigators also studied those cases 

of isomerism in which the nitrogen behaves as 

(II) s"~& a P en t ava l en * element. 

SEPARATION AND TRANSFORM A- 
TION OF STEREOISOMERIDES. Stereo- 
isomerides and, in general, compounds contain- 
ing asymmetric carbon atoms, when prepared 

p . a C b artificially in the laboratory from inactive 

it || substances, are inactive, the racemic configura- 

^ jj N c tion, composed of a mixture of the optical 

YIG. 39. antipodes in equal quantities, being formed. 

When, however, these substances are elabo- 
rated in the animal or vegetable organism, they are usually optically active. 

The transformation of one of these optical antipodes into the other corresponding with 
it may sometimes be effected by passing through halogen derivatives, separation of the 
halogen from which results in the formation of the isomeride of opposite optical activity. 
The separation of the antipodes, or of one of them, from the racemic isomeride was 
carried out by Pasteur (1848) in various ways. The following are the methods used at 
the present time : 

(1) By fractional crystallisation (see above) of the racemic isomerides or of some of 
their salts at various temperatures and from various solvents, the antipodes can be sepa- 
rated directly or else they crystallise in hemihedral forms which can be readily separated. 
For some substances, it is convenient to prepare compounds with alkaloids (optically active 
basic compounds, e.g. strychnine, cinchonine, &c.), which, even when they do not form 
well-defined hemihedral crystals, can be easily separated by fractional crystallisation. 

(2) By means of enzyme action (maltase, emulsin, &c. ; see section on Fermentation), 
Fischer succeeded in resolving certain racemic glucosides. Much earlier than this, 
Pasteur discovered that certain bacteria or moulds (Penicillium glaucum, &c.) are capable 
of developing in a solution of the racemic substance at the expense of one of the optical 
antipodes, the other being left unchanged. This phenomenon is explained by the fact 
that bacteria owe their activity to certain substances which they produce (enzymes), 
and which are optically active and behave analogously to optically active solvents. 
Indeed, in many cases, stereoisomeric antipodes are separated by virtue of their different 
solubilities in an optically active solvent. 

(3) With certain racemic compounds, the antipodes are separated by taking advantage 
of their different velocities of esterification in presence of an optically active alcohol ; 
e.g. for racemic mandelic acid, menthol (which is an active alcohol) is used. For inactive 
alcohols, the velocity of esterification is the same for the two antipodes composing the 
racemic compound. 

(4) When an optically active substance is heated within certain definite limits of 
temperature (transformation point, see vol. i, p. 190), it is often converted, to the extent 



HOMOLOGY AND ISOLOGY 23 

of one-half, into the oppositely active isomeride, so that an inactive mixture (racemic 
compound) is obtained ; this takes place readily, for example, with the lactic acids. 
Above the transformation point the racemic substance may form inseparable mixed 
crystals (see vol. i, p. Ill), the substance being then called pseudo-racemic. On the other 
hand, it has been shown that, with certain halogenated compounds, the transformation 
occurs even at ordinary temperatures, but with a minimum velocity ; thus, with isobutyl 
bromopropionate, about three years is required. 

(5) R. Stoermer (1909) found that the more stable form with the higher melting-point 
is often converted into the more labile form by means of the ultra-violet rays. 

HOMOLOGY AND ISOLOGY 

Turning to the more simple compounds, those formed from only carbon 
and hydrogen, we can easily see what procedure is necessary to arrive at 
those containing longer and more complex chains of carbon atoms. If we 
start from the most simple compound, methane (or marsh gas), CH 4 , we can 
substitute an atom of hydrogen in it by other elements or even condense two 
of the monovalent CH 3 residues into one compound, CH 3 'CH 3 , thus obtaining 
ethane (C 2 H 6 ). But in this compound we can also replace an atom of hydrogen 
by another CH 3 residue, forming propane, CH 3 CH 2 CH 3 or C 3 H 8 , and 
by continuing this process we arrive at butane, CH 3 CH 2 CH 2 CH 3 , i.e. 
C 4 H, , ; pentane, C 5 H 12 ; hexane, C 6 H 14 , &c. 

All the compounds of this series have analogous structures and have also 
many analogous chemical and physical properties ; such a series is called a 
homologous series. 

This series of the derivatives of methane can be represented by the general 
formula C w H 2w + 2 , each term being the higher or lower homologue of the pre- 
ceding or following term and differing from it by having one CH 2 complex 
more or less. If in all the simple compounds of this homologous series of 
methane we replace successively one hydrogen atom of the CH 3 group by the 
hydroxyl residue OH (characteristic of the alcohols) we obtain a homologous 
series of alcohols : CH 3 OH, methyl alcohol; C 2 H 5 OH, ethyl alcohol, <fec., and 
similar series can be obtained of aldehydes, acids, chloro-derivatives, &c. 

The homologous compounds of each of these series differ always by CH 2 
or by a multiple of it. 

There are also other series with chains containing double linkings (i.e. 
compounds not completely saturated), and these unsaturated series are termed 
isologous with respect to the first, and, for an equal number of carbon atoms, 
they contain less hydrogen (C W H 2W or even C n H 2w _ 2 ). 

Thus, ethane is isologous to the two-carbon-atom compounds of the 
unsaturated series, CH 2 =CH 2 (ethylene) and CH=CH (acetylene), &c. 

Homology is determined by the tetra valency of carbon, and in consequence 
the total number of hydrogen atoms in these compounds (hydrocarbons) is 
always even, i.e. divisible by two, and, if any of the hydrogen atoms 
are replaced by other elements, the sum of the atoms with odd valencies 
(Cl, P, N, As), and of the remaining hydrogen atoms should always give an 
even number. 

PHYSICAL PROPERTIES OF ORGANIC SUBSTANCES IN RELATION 
TO COMPOSITION AND CHEMICAL CONSTITUTION 

In many cases, certain physical properties are either common to whole 
groups of homologous or isomeric substances, or else vary gradually with 
change of chemical composition. So that the physical properties often con- 
tribute to the establishment of the true chemical constitutions of organic 
substances. 



24 ORGANIC CHEMISTRY 

CRYSTALLINE FORM. The crystalline form of an organic compound is of con- 
siderable importance, since it often serves to distinguish clearly and accurately between 
two compounds. Two isomeric substances have often different crystalline forms. 

There are, however, numerous cases of dimorphism or polymorphism (see vol. i), one 
of the forms always being more stable than the others. 

We have already considered the relations existing between the crystalline form and 
chemical constitution in those stereoisomerides differing only by the enantiomorphism 
of their crystals. 

P. Groth has discovered also the law of morpTiotropy, according to which a regular 
change is produced in the crystalline form of compounds by gradual substitution with 
new atoms or groups. 

The relations between the crystalline forms and the chemical constitutions of sub- 
stances have as yet, however, been little studied. 

SOLUBILITY. The hydrocarbons and their substitution derivatives are but slightly 
or not at all soluble in water, but are almost all soluble in ether and in alcohol. Of the 
alcohols, the acids, and the aldehydes, the first terms of every homologous series are 
soluble in water, the solubility gradually decreasing as the number of carbon atoms in 
the molecule increases ; these compounds are, however, relatively readily soluble in 
alcohol or ether. The polyhydric alcohols (glycerol, mannitol, &c.), are, however, soluble 
in water, but not in ether. 

The compounds of the aromatic series are, in general, rather less soluble in alcohol 
and in water than the corresponding compounds of the fatty series. 

In contact with two solvents which do not mix (see vol. i, p. 90), a substance dis- 
solves in them both in a constant ratio, independent of the relative volumes of the two 
solvents, but depending on the concentration and on the temperature ; thus, in separating 
by means of ether a compound dissolved in water, a better and more rapid result is 
obtained by shaking many times with a little ether each time than by using fewer, but 
larger, quantities of ether. 

Of two isomerides, that with the lower melting-point is the more soluble. 
SPECIFIC GRAVITY. Isomeric compounds have different specific gravities, but 
with the normal hydrocarbons (C,,H 2 , ( _|_2)> the values approach one another as the number 
of carbon atoms increases : at about C^H^ and for higher terms, the specific gravity 
becomes about 0-78. The specific gravity of the monobasic fatty acids is greater than 
1 for the first terms of the series, but it diminishes with augmentation of the number of 
carbon atoms in the molecule. 

MOLECULAR VOLUME. It was thought for many years that certain important 
rules could be deduced from the molecular volumes of organic compounds, that is, from 
the quotients, M/P, obtained by dividing the molecular weights (M) by the specific 
gravities (P), 

In 1842 Kopp had found that, for liquids at the boiling-point, the molecular volume 
is very approximately equal to the sum of the atomic volumes of the component elements. 
For homologous compounds, the molecular volume increases by about 22 for every added 
CH 2 group. More recent studies (Lessen, R. Schiff, Horstmann, Traube, &c.) show, 
however, that these regularities are only relative and that isomeric compounds do not 
possess equal molecular volumes. In unsaturated series, every double linking increases the 
molecular volume and, with closed-chain compounds, the molecular volume is less than 
those of the corresponding open-chain compounds with double linkings. So that, in 
general, the molecular volume depends not only on additive factors (e.g. the sum of the 
atomic volumes), but also on constitutive factors (different linkings between the carbon 
atoms). 

MELTING-POINT. Of two isomerides, that with the more symmetrical structure 
has the higher melting-point. The members of a series have varying melting-points, 
those with odd numbers of carbon atoms having lower melting-points than those imme- 
diately below them with even numbers. There are, in addition, other less important 
rules, but all present exceptions. A mixture of two substances, in suitable proportions, 
often has a melting-point lower than that of either of the components. 

BOILING-POINT. In compounds of the same series, the boiling-point rises with 
increase of molecular weight, the amount of the increase being about 20 per CH 2 in the 
methyl alcohol or formic acid series and about 30 for benzene derivatives with methyl 



THERMAL RELATIONS 



25 



groups in the nucleus. The boiling-points of isologous hydrocarbons, that is, those of 
the same number of carbon atoms but of different series (derivatives of methane, ethylene, 
and acetylene) are very close to one another. 

Of the isomeric compounds of the aliphatic series, the normal one boils at the highest 
temperature and the boiling-point is increasingly lowered by increase in the branchings. 

The substitution of hydrogen by halogens and by hydroxyl groups raises the boiling- 
point. The ethers boil at lower temperatures than the corresponding isomeric alcohols. 

HEAT OF COMBUSTION AND HEAT OF FORMATION FROM THE ELEMENTS 
(see vol. i, pp. 60, 109, 372). The Hess-Berthelot law states that the difference between 
the heats of combustion of two equivalent chemical systems is equal to the heat developed in the 
transformation of one system into the other, that is, is equal to the heat of formation from 
the elements of this latter. In general, we can hence calculate the heat of formation from 
its elements of an organic compound by subtracting its heat of combustion from the sum 
of the heats of combustion of the elements composing it. As an example : the heat of 
combustion of methane, CH 4 , at constant volume is 211,900 cals. ; the heat of combustion 
of carbon (C + 2 = C0 2 ) being 97,000 cals. and that of hydrogen (H 2 + O '= H 2 0) 
68,400 cals., the complete combustion of methane is given by the following equation : 
CH 4 + 2O 2 = C0 2 + 2H 2 O = 97,000 + (2 x 68,400) = 233,800 cals., the sum of the 
heats of combustion of the component elements of methane. The heat of formation of 
methane will then be given by : 233,800 - 211,900 = 21,900 cals., which also represents 
the heat necessary to resolve methane into its elements in order to initiate its combustion. 
The heat of combustion of ethyl alcohol being 340,000 cals., that of acetic acid 210,000, 
and that of ethyl acetate 554,000, the heat of formation of the last named from the first 
two will be : 340,OQO + 210,000 - 554,000 = - 4000 cals. 

In the analogous paraffin and olefine series, a difference of CH 2 corresponds with a 
variation of 150,000-160,000 cals. in the molecular heat of combustion. 

The heats of combustion of isomeric compounds are equal, if they are chemically 
similar, for example, methyl acetate (CH 3 -CO 2 CH 3 ) and ethyl formate (H'C0 2 C 2 H 5 ), 
but different if the compounds are of different molecular character (for example, allyl 
alcohol, CH 2 : CH-CH 2 -OH, and acetone, CH 3 -CO-CH 3 ), compounds with multiple 
linking in the fatty series having higher heats of combustion than the corresponding 
cyclic isomerides. 

These calculations are also of importance for the evaluation of the energy produced in 
organisms by the transformations of various foods (see also later in the section on 
Explosives 1 ). 

HEAT OF NEUTRALISATION. With the organic acids this is the same for all, 
namely, 13,700 cals. (see vol. i, p. 97), as long as the resulting salts are not decomposed 
by water ; with the phenols (cyclic compounds containing OH) the heat of neutralisation 
is about one-half the above value, or more if the acid character is intensified by the 
presence of the NO 2 group ; with the alcohols it is almost zero. 

1 The following are the heats of formation from the elements of certain organic compounds, expressed in large 
calories per gramme-molecule : 

Naphthalene, C 10 H 8 : solid . . . -42 Cals. 

Nitronaphthalene, C 10 H,NO 2 : solid . 14-7 

Dinitronaphthalene, C 10 H 6 (NO 2 ) i : solid 5-7 
Trinitronaphthalene, C 10 H 6 (NOji)3 solid. 3-3 

Acetylene, C 2 H 2 : gas .... 61-4 

Ethylene C 2 H 4 : gas . '..'*". . 15-4 

Benzene, C,H, : gas . . .... . 10-2 

Nitrobenzene, C,H 6 N0 2 : liquid . . 4'2 
Dinitrobenzene, C,H 4 (NO 2 ) 2 : solid . 12-7 

Mannitol, C e H 14 : solid . . . 320 

Nitromannitol, C e H 8 N,O 18 : solid . . 179' 1 

Mercury fulminate, C 2 N 2 Os,Hg : solid . 62-9 
Anthracene, C 14 H 10 : solid . . 



Methyl alcohol, CH S OH : liquid . . 62 Cals. 

Ethyl alcohol, C,H 5 OH : liquid . . 70-5 

Phenol, C,H 6 OH : liquid . . . 34-5 
Trinitrophenol (picric acid),C,H 2 OH(NO 2 ), 

solid 49-1 

Sodium picrate, CH 2 ONa(NO,) 8 : solid 117-5 

80-] 

65-3 

72 

Glycerol, C 3 H 6 (OH), : liquid . . . 165-5 

Trinitroglycerol, C,H,(ONO 2 ) 3 : liquid . 196 ,, 
Cellulose (cotton), C 6 H 10 O 5 : solid . . 227 



Ammonium picrate, solid 
Ether, (C 8 H.) 2 o{** s uid ; 



Nitrocellulose, solid 



624-696-706 



-42-4 

and the heats oj combustion of various organic compounds are as follow : ethyl alcohol, 340 cals. ; methyl 
alcohol, 182-2 ; mannitol, 727 ; cellulose, 680 ; terephthalic acid, 771 ; diphenyl, 1494 ; cane sugar, 1355 ; acetic 
acid, 210 ; benzole acid, 772 ; ethyl acetate, 554 ; urea, 152 ; benzene, 779-8 ; dihydrobeniene, 848 ; tetra- 
hydrobenzene, 892 ; toluene, 933 ; hexane, 991-2 ; methane, 211-9 ; ethane, 370-4 ; propane, 529-2 ; trimethyl- 
methane, 687-2 ; ethylene, 333-4 ; propylene, 492-7 ; trimethylene, 499-4 ; isobutylene, 650-6 ; methyl chloride, 
164-7 ; ethyl chloride, 321-9 ; propyl chloride, 480-2 ; chloroform, 70-5 ; dinitrobenzene (o-, m-, and p-), about 
700 ; trinitrobenzene, 666 681 ; succinic acid, 357 ; azelaic acid, 1141 ; erucic acid, 3297 ; tribrassidinic acid, 
10,236 ; glucose, 674 ; oxalic acid, 60-2 ; formic acid, 62-8 ; hydrocyanic acid, 152-3 ; naphthalene. 1233-6 ; 
phenol, 732 ; pyrogallol, 639. 



26 



ORGANIC CHEMISTRY 



OPTICAL PROPERTIES. (1) Colour. The majority of organic compounds are 
colourless, but if they contain iodine or the nitro -group or doubly linked nitrogen atoms 
( N=N ), or two oxygen atoms directly united, they are generally coloured, especially 
in the aromatic series. 

In the section on Dyes are given detailed illustrations of the remarkable relations 
between the chemical constitution of organic compounds and their colour. 

(2) Refraction. This is the deviation produced in the direction of a ray of light 
(homogeneous ; for example, sodium light) on passing through a transparent liquid, and 
varies with the substance. The index of refraction n varies with the temperature, and 
hence with the specific gravity (d) of the substance. The relation between these two 

1 1 

R. 



values which gives the refraction constant R (or specific refractivity) is : 
which is almost independent of the temperature. 



n 2 +2.' d 
By multiplying by the molecular 

n 2 1 P 

weight P, the molecular refraction is obtained : M = -r ~ -5 , this being constant for 

n ~\~ d 

true isomerides and changing by a constant amount for a constant change in the 
composition. 

The molecular refraction of a compound is approximately equal to the sum of the 
elementary atomic refractions, but here double and triple linkings have an influence, so 
that these can be detected in an organic compound by means of the refraction (true double 
linkings of the aliphatic series are often distinguished in this way from the cyclic linkings 
of benzene). 

(3) Polarised Light. Owing to the importance of this phenomenon for whole groups 
of organic substances, it will be useful to recall briefly in a note 1 the fundamental ideas 
on polarised light. 




FIG. 40. 



1 The luminous waves of white light are propagated in the cosmic ether with velocity of about 300,000 kilo- 
metres per second, and there are physical instruments which admit of the measurement of the time required for a 

ray of light to traverse a few metres ; indeed, Foucault measured 

the time taken by light to pass over a distance of 120 metres. 
By studying the phenomena of interference of light rays, it 

can be shown that the vibrations of the ether in them are not 

longitudinal, i.e. along the direction of propagation of the ray, 

but that the et'her particles vibrate in all directions in a plane 

perpendicular to. the direction of the ray (a transverse section 

of a ray is shown in Fig. 40), whilst the propagation of sound 

is effected by means of longitudinal vibrations in the direction 

of the path traversed by the sound. 

A ray that enters a liquid or a non-crystalline solid, or a crystal of the regular 
system (cube or octahedron) gives only one refracted ray ; when it enters a 
crystal of the rhombohedral system, two refracted rays are formed, one extra- 
ordinary and the other ordinary ; when a ray enters a crystal of any other system, 
two refracted rays are formed, but these rays both behave likp the extraordinary 
ray, and, like the latter, they do not obey the laws of refraction, according to 
which an incident ray, perpendicular to a medium with parallel faces, should not 
be deviated or refracted. 

If a ray of light, J i (Fig. 41) strikes a rhombohedral crystal of Iceland spar 
perpendicularly to the face ABCD, the ray divides into two. The one, ioO, 
continues in the same direction, the other, ie, is deviated, but when it emerges 
from the crystal assumes the direction e E, parallel to the original direction. The 
two parallel rays leaving the crystal have equal luminosities, but o follows the 




FIG. 41. 



O 




FIG. 42. 



FIG. 43. 



ordinary laws of refraction (vide 
supra) and is called the ordinary 
ray, whilst the other, eE, does not 
obey these laws and is termed the 
extraordinary ray. 

If the crystal is rotated about 
the incident ray Ji as an imaginary 
axis, the position of the ray o does 
not change, whilst the ray e E moves 
in the sense in which the crystal is 
rotated. The extraordinary ray i E 

always lies in the plane of the principal axis of the crystal dbBD, which passes through the principal axis of the crystal 
b O and is parallel to it. These two rays emerging from the crystal have, however, properties different from those 
of the incident ray J i ; in fact, if either of the two refracted rays (eE or o O) is passed into a second rhombohedron 
of Iceland spar, two new rays (double refraction) are obtained, but the intensities of the two rays vary according 
to the relative positions of the two crystals. Thus, if a ray emerging from the first crystal passes porpendiculaily 
into the second crystal, the principal section cf which is parallel to that of the first, no double refraction is observed, 
only one ray leaving the second crystal (s in Fig. 42, the second hypothetical ray n not being visible and marked 
black in the figure). If, however, the second crystal is rotated round the imaginary axis, o O, a second ray (extia- 
ordinary) suddenly appears, i.e. double refraction takes place, and whilst the luminosity of the new lay increases, 



OPTICAL ROTATION 27 

Those organic substances are called optically active which rotate the plane of polarised 
light. Some substances are optically active in the crystalline state (not in the amorphous 
state or in solution), and hence the action on polarised light is due in these cases to the 
peculiar arrangement of the molecules ; very few are active in both the crystalline and 
amorphous states, the majority exhibiting activity only in a dissolved condition (sugars, 
&c.), where the phenomenon depends on the arrangement of the atoms or groups of atoms 
in the molecule. This holds also for camphor and oil of turpentine, which are active even 
in the form of vapour. 

The longer the layer (I) and the greater the concentration of the solution (p = grammes 
of dissolved substance in 100 of solution) traversed by the polarised light, the greater 
will be the rotation of the plane of polarisation. Referring the observed rotation a to a 
length of 10 cm. of a solution containing 1 grm. of pure substance in 1 c.c. ( = pdjlOO, 
where d is the specific gravity of the solution), we get the specific rotatory power of the 
solution for the yellow sodium light (D line of the spectrum x ) by means of the following 

1 00 

formula : fain = ; ; For active liquid substances examined without solvent, 
I'd- p 

[ a ] D = - . The molecular rotation (for a molecular weight M) is given by : [M] = 

For a definite solvent and given concentration and temperature, every active substance 
(and such are almost all those containing asymmetric carbon, see p. 26) has a constant and 
characteristic specific rotatory power, either to the right ( +) or to the left ( - ). This 
varies with the nature and degree of electrolytic dissociation of the solvent, and increases 
with dilution and diminishes with rise of temperature ; for purposes of comparison, it is 
usually determined at 20, and is then indicated thus : [a] D. By repeating the determina- 
tions and using moderately high concentrations, the influence due to the solvent is deter- 
mined and, on subtracting this, the true specific rotation is obtained. Freshly prepared 
solutions of certain sugars exhibit the phenomenon of muta-rotation, which, however, 
disappears after a time or on boiling the liquid, the normal rotation then being 
given. 

This important property of optically active compounds is studied by means of special 
apparatus termed polarimeters, which are used particularly in the analysis of sugars 
(and hence often called saccharimeters), and will be described in the section dealing with 
this group of substances. 

MAGNETIC ROTATORY POWER. All liquids in a magnetic field produce a greater 
or less rotation of the plane of polarised light, according to their chemical composition 
and in conformity with the laws governing the refractivity of light. In many cases the 
constitution of a substance has been determined or confirmed by determining the 
molecular magnetic rotation. 

ELECTRICAL CONDUCTIVITY. We must refer the reader to the detailed treat- 
ment of electrolytic dissociation and the theory of ions in vol. i (pp. 91 et seq.), as the 
same is directly applicable to organic compounds, especially as regards the conductivity 
of salts, acids, bases, &c. 

that of the first ray becomes weaker and when the principal sections of the two crystals form an angle of 45, the 
two rays have equal intensities (', n') ; if the crystal is rotated still more, the extraordinary ray becomes more 
luminous, whilst the first (ordinary) decreases in luminosity, and when the principal sections are perpendicular to 
one another, the intensity of the ordinary ray (*") is aero (i.e. it is not seen), only the extraordinary ray being 
seen with its maximum intensity (n"). The light rays emerging from the second rhombohedron are hence 
different from those emerging from the first, these latter not varying in intensity when the prism is rotated, whilst 
the others do so. 

The rays leaving the first prism are called polarised, and are distinguished from ordinary light rays, since, on 
passing through a second prism, they undergo the changes described above. A polarised ray passes as an ordinary 
ray through a second rhombohedron only when its plane of polarisation is parallel to the principal section of the new 
rhombohedron It ia found, then, that the plane of polarisation of the polarised ordinary ray is perpendicular to 
the plane of polarisation of the extraordinary ray. Hence, the rays E and O vibrate in planes perpendicular 
to one another (Fig. 43). 

POLARISATION BY REFLECTION. Polarised light rays are obtainable, not only by double refraction, but also 
by reflection under special conditions, namely, when a light ray falls on a plate of glass at an incident angle 
of 54 35'. 

Polarised light is also obtained by simple refraction, by passing a ray of light through a series of superposed 
parallel plates or sheets of tourmaline. 

1 The angle of rotation varies with the length of the light- wave and is greater for violet rays (which have a smaller 
wave-length and are hence refracted more) and less for red rays (which have a greater wave-length and are hence 
less refrangible). 



28 ORGANIC CHEMISTRY 

CLASSIFICATION OF ORGANIC SUBSTANCES 

These are usually divided into two large series : 

(1) That of the open-chain carbon compounds or methane derivatives, termed 
also compounds of the fatty or aliphatic series, as all the fats and many of their 
derivatives belong here. This series embraces two groups of substances ; 
that of the saturated compounds or derivatives of the paraffins (C n H 2n + 2 ) and 
that of the unsaturated compounds (olefines, C n H 2w and derivatives of acetylene, 

(2) That of the closed-chain carbon derivatives, this being subdivided into : 

(a) The isocyclic or carbocyclic compounds, which have the closed chain 
formed either of nuclei of six carbon atoms with six available valencies to 
every nucleus (C n H 2n _ 6 , benzene derivatives or aromatic compounds] or from 
nuclei with different numbers of carbon atoms, but more highly hydrogenated 
(cycloparaffins, cyclo-olefines, and polymethylene derivatives). 

(b] The heterocyclic compounds, the closed chain of which contains atoms 
(N, P, S, 0, &c.) other than carbon. 

The hydrogenated compounds of' carbon are called hydrocarbons and are 
termed saturated when the carbon atoms are joined by single valencies, and 
the other valencies are all satisfied by hydrogen. These saturated hydro- 
carbons cannot combine with a further quantity of hydrogen. 

Hydrocarbons containing carbon atoms united by double or triple linkings 
are called unsaturated hydrocarbons, and these can combine with further 
quantities of hydrogen, thus becoming saturated. Other important hydro- 
carbons are those with closed chains, which we shall study in Part III of this 
book. 

Usually in homologous series, with increase in the number of carbon atoms, 
the compounds pass from the gaseous to the liquid and solid states ; 
e.g. formic acid, with one carbon atom, is a liquid and boils at 99, while the 
homologous acid with six carbon atoms is a solid and boils at over 300. 

OFFICIAL NOMENCLATURE 

With the continuous development of organic chemistry and the multiplication of new 
compounds, the need was often felt for a rational method of naming compounds which 
would facilitate the treatment of these vast numbers of compounds. And for the new 
nomenclature to be the more efficacious it needed to be international, because everywhere 
there reigned the greatest confusion in the naming of chemical compounds, this referring 
either to the starting substance or to the new group to which they belonged, or to the 
use for which they were intended, or to the molecular constitution, and so on, so that 
the same substances often had four or five names. 

f". In 1892, at an International Convention of Chemists at Geneva, a general system of 
nomenclature of organic compounds was agreed on. This is gradually being introduced 
into chemical literature, and, although not always felicitous, it has helped to simplify the 
naming of compounds and to reduce the confusion. 

Following only in part the ideas proposed by Kolbe many years before, the new 
nomenclature derives the names of all compounds from the names of the fundamental 
hydrocarbons to which the compounds can be referred, taking into account the number of 
carbon atoms present as well as the nature of the linking. Thus, to the fundamental 
names of the saturated hydrocarbons : methane, ethane, propane, butane, pentane, 
hexane, heptane, &c., the addition of the suffix ol indicates the presence of the hydro xyl 
group OH, and thus an alcohol, for example, methanol (methyl alcohol), efhanol (ethyl 

alcohol), &c. ; the suffix al serves to denote the aldehyde group ( C^ ) , thus, e.g. 
methanal = formaldehyde, ethanal = acetaldehyde, &c. ; the suffix one indicates the 



OFFICIAL NOMENCLATURE 29 

ketonic group ( CO ), thus, propanone (commonly called acetone), &c. The suffix 
oic is used to indicate the organic acids, which all contain the characteristic carboxyl 

( / \ 

group I C0 2 H, i.e. C<T 1, and thus we have methanoic (formic) acid, ethanoic 

V X; 



acid, propanoic (propionic) acid, bwtanoic acid, pentanoic acid, &c. 

For the unsaturated doubly linked hydrocarbons the fundamental hydrocarbon 
ethylene is distinguished with the name of ethene, and that with a triple bond between the 
two carbon atoms (acetylene) is called ethine. 

With the saturated hydrocarbons, isomerides with branched chains are referred to the 
normal hydrocarbon (i.e. non-branched) with the longest chain present in the molecule, 
numbering progressively its carbon atoms, starting at the end nearest to the point where 
branching occurs. The name begins with that of the residue of the side-chain, 1 then 
follow the successive numbers of the atoms of the normal chain where side-chains join 
on, and finally comes the name of the normal hydrocarbon. 

(1) (2) (3) 
CH 3 CH CH 3 

CH 3 

bears the official name methyl-2 -propane (some call it propyl-2 -methane), and isopentane, 

(1) (2) (3) (4) 
CH 3 Gii O-fcla CH 3 

CH 3 

that of methyl-2 -butane, &c. 

When there are also secondary ramifications a supplementary numbering is used ; 
thus, with isodecane, 

(1) (2) (3) (4) (5) (6) (7) 
CH 3 CH2 CH 2 CH CH 2 CH 2 CH 3 

(41 ) CH CH 3 

(4 n ) CH 3 
the official name would be metho-4 I -ethyl-4-heptane. 

1 The names of the hydrocarbon residues, called ateo alkyl groups, are formed from the root of the name of the 
corresponding hydrocarbon, with the suffix yl ; thus, with methane corresponds the methyl residue CH, ; with 
ethane, ethyl. C 2 H, ; and then follow propyl, : C,H, ; butyl, 4 H,, &c. 



PART II. DERIVATIVES OF METHANE 

AA. HYDROCARBONS 

THE hydrocarbons form a very large and important group of organic 
substances, which are composed only of hydrogen and carbon, and give rise 
to other most varied substances by replacement of part or all of the hydrogen 
by other elements or groups. 

For the reasons given on p. 28, they are divided into two main groups : 
saturated and unsaturated hydrocarbons. 

(a) SATURATED HYDROCARBONS 

These are called saturated because the linkings between the carbon atoms 
are simple ones and ah 1 the valencies are saturated, so that hydrogen, chlorine, 
bromine, iodine, ozone, &c., cannot be added to them ; the halogens do, indeed, 
react with saturated hydrocarbons (fluorine reacts with methane even at 
187), but by substitution of the hydrogen atoms. 

They are called also paraffins, since, like the common solid paraffins, all 
the saturated hydrocarbons resist, in the cold, the action of chromic acid, 
potassium permanganate, and concentrated nitric and sulphuric acids, and 
are, in general, compounds with an almost indifferent chemical character. 
In the hot, however, energetic oxidising agents convert them, more or less 
completely, into carbon dioxide and water. 

As a general rule, these hydrocarbons are insoluble in water and only 
some of them dissolve in alcohol, whilst almost all are soluble in ether. 

Of the direct or continuous (normal) and branched (isomeric) open chains , 
mention has already been made on pp. 15, 16, and 28, and it can be seen how, 
starting from the hydrocarbon, 4 H 10 , the number of isomerides rapidly 
increases : 2 for butane ; 3 for pentane, C 5 H 12 ; 5 for hexane, C 6 H 14 (all 
known) ; while for C 12 H 26 the number theoretically possible is 355 and for 
C 13 H 28 , 892, only some of which are, however, known. All the terms of the 
paraffin series can be represented by the general formula C M H 2n + 2 , and 
the following Table (p. 31) gives the name, formula, boiling-point, and melting- 
point of the principal known paraffins. The official nomenclature is described 
on p. 28. 

The first members of the series are gases, then follow liquids as far as 
C 15 , and beyond that, solids, the boiling- and melting-points rising with increase 
of the molecular weight (see p. 24). 

NATURAL FORMATION AND GENERAL METHODS OF PRO- 
DUCTION. These hydrocarbons, from the lowest gaseous members to the 
highest solid ones (paraffin), occur abundantly as the almost exclusive com- 
ponents of petroleum (especially that from America), and it is not difficult 
to separate single individuals from these complex mixtures. 

In many natural emanations of inflammable gas, methane and, to some 
extent, ethane are found in large proportions, and the solid hydrocarbons 
occur also in ozokerite (which see). 

30 



SATURATED HYDROCARBONS 



31 



The gaseous, liquid, and solid hydrocarbons are formed abundantly on the 
dry distillation of wood, lignite, bituminous schists, and coal, especially boghead 
and cannel coals which are relatively rich in hydrogen (see Illuminating 

SATURATED HYDROCARBONS, C n H 2n + 2 
(After hexane, only the normal ones are given) 





Melting-point 


Boiling-point 


Specific Gravity 


CH 4 Methane 


-184 


-164 


0-415 (-164) 






(760 mm.) 


0-555 










(0, 760 mm.) 


C 2 H 6 Ethane . . 


-172-1 


-84-1 


} 


0-446 (0) 






(749 mm.) 








(0at23-8atm.) 




C 3 H 8 Propane . . . 


-45 


-44-5 


0-535 






(0at5atms.) 


(0, liquid) 


( normal . . 
C 4 H 10 Butanes i . 
I isobutane , 





+ 1 
-17 




0-600 (0) 
0-6029 (0) 


rnormal . 


-200 


+ 36-3 


o 


0-454 (0) 


C 5 H 12 Pentanes-^ isopentane 





+ 30-4 





0-622 ^ 


I tertiary . 


-20 


+ 9 




at 


normal . . 





69 




0-6603 I** 
20 


dimethylisopropyl - 










methane . . 





58 




0-666 J 


dimethylpropyl - 










C 6 H 14 Hexanes J methane 





62 




0-6766 (0) 


methyldiethyl- 










methane 





64 




0-677 <^ 


trimethylethyl - 












methane ' . 





49-6 


o 


0-6488 




C 7 H 16 Heptane . , . 





98-3 


e 


0-683 


at 


C 8 H 18 Octane . 


. 


125-8 


o 


0-702 




C 9 H 20 Nonane . . . . 


-51 


150 




0-718 




CioHaa Decane . . . - . . 


-31 


173 




0-7467^ 


CnH 24 Undecane . . . . 


-26 


196 




0-758L 


C 12 H 26 Dodecane . . 


-12 


215 




0-7684 




Ci 3 H 28 Tridecane . ,/. , .. 


- 6 


234 




0-775 




CWHso Tetradecane . , . . 


+ 4 


252 




0-775 




^15^32 Pentadecane . . . 


+ 10 


270 




0-776 




CieH 3 4 Hexadecane . 


18 


287 




0-775 




Qi7H 36 Heptadecane . . 


22 


303 




0-777 




CigHss Octodecane .... 


28 


317 




0-777 


"5 


^19^40 Nonodecane . . . . 


32 


330 




0-777 


'o 


C 20 H 42 Eicosane , 


37 


205^ 




0-778 


bn 


C 21 H 44 Heneicosane . . . * 


40 


215 




0-778 


>45 


^22^46 Docosane .... 


44 


224 





0-778 


f a 


^23^8 Tricosane .... 


48 


234 


ft 
rr. 


0-779 





^WHso Tetracosane . . . 


51 


243 


00 

0) 


0-779 


"^ 


C 25 H 52 Pentacosane .... 


53-5 





ft 





a 


^26^54 Hexacosane .... 


58 





^a 







C 27 H 56 Heptacosane .... 


60 


270 


a 

>o 


0-780 




C2sH 58 Octocosane .... 


60 





11 







^31^64 Hentriacontane 


68 


302 





0-781 




^32^66 Dotricontane (Dicetyl) 


70 


310 




0-781 




^35^12 Pentatricontane . " . 


75 


331 ) 




0-782 / 


C 60 H 12 2 Hexacontane .... 


101 











32 ORGANIC CHEMISTRY 

Gas) ; also when petroleum residues are strongly heated under pressure 
(cracking), hydrocarbons similar to petroleum and also gaseous ones are 
formed. 

Of the numerous synthetical methods of preparation of the saturated 
hydrocarbons, the following more important ones may be mentioned : 

(a) Any member of the series can be obtained by reducing the halogen derivatives 
of the hydrocarbon (obtained from the alcohols and the halogen hydracids) by means of 
nascent hydrogen (generated by sodium amalgam, or by a solution of sodium in absolute 
alcohol, or by zinc and hydrochloric acid, or by heating zinc and water at 160) or by 
hydriodic acid, especially in the presence of red phosphorus (which transforms the iodine 
into hydriodic acid) : C 2 H 5 I + H 2 = HI + C 2 H 6 ; C 2 H 5 I + HI = I 2 + C 2 H 6 (see Table 
of the halogen derivatives of the hydrocarbons). 

(b) The alcohols give paraffins on being heated with hydriodic acid : 

C 2 H 6 -OH + 2HI = H 2 O + I 2 + C 2 H 6 . 

(c) By the interaction of zinc alkyls and water : 

Zn(C 2 H 6 ) 2 + 2H 2 = Zn(OH) 2 + 2C 2 H 6 . 

(d) From unsaturated hydrocarbons by the action of hydrogen, e.g. by heating acetylene 
and hydrogen at 400*-500, or in presence of platinum -black. 

(e) By eliminating a molecule of carbon dioxide from the organic acids and salts by 
heating with soda-lime or sodium alkoxide : 

CH 3 .COONa (sodium acetate) + NaOH = Na 2 C0 3 + CH 4 . 

(/) By the action of sodium or of zinc on the zinc alkyls or alkyl iodides in ethereal 
solution in a closed tube (Wurtz), two alkyl groups, even different ones, being condensed : 

(1) 2CH 3 I + Na 2 = 2NaI + C 2 H 6 . 

(2) C 2 H 6 I + C 4 H 9 I + Na 2 = 2NaI + C2H 5 .C 4 H 9 . 

(3) 2CH 3 I + Zn(CH 3 ) 2 = ZnI 2 + 2C 2 H 6 . 

(g) During the last few years it has been shown that magnesium is much more active 
than zinc in many organic syntheses (see later, Grignard Reaction), and with alkyl iodides 
dissolved in absolute ether, magnesium forms magnesium alkyl salts which, on decomposi- 
tion by means of water or dilute acid or ammonia with solid ammonium chloride, yield 
the saturated hydrocarbons : C 2 H 6 I + Mg = C 2 H 5 MgI, and this + H 2 O = C 2 H 6 + 
Mg(OH)I. In part, however, the magnesium fixes the halogen, and then two alkyl 
residues condense, forming a hydrocarbon of double the number of carbon atoms : 

2C 2 H 6 I + Mg = MgI 2 + C 4 H 10 . 

(h) Sabatier and Senderens' catalytic process, for which see pp. 34 and 59. 
(i) By electrolysing acetic acid : 

CH 3 COOH CH 3 

+ 2C0 2 + H 2 
CH 3 COOH CH 3 

the hydrogen going to the negative pole and the hydrocarbon and carbon dioxide to the 
positive one. 

METHANE (MARSH GAS), CH 4 

This is a gas which is often found ready formed in nature, and in former 
times it was always confused with hydrogen .(inflammable air). Pliny refers 
to the gases which exude from the earth in certain regions and are inflam- 
mable (these are probably the sacred fires of the ancient Chaldeans). Basil 
Valentine (1500) records fires in mines preceded by the emanation of asphyxi- 
ating, poisonous vapours, which are dispersed and rendered innocuous by the 
fire issuing from the rock. Also Libavius (1600) speaks of the inflammable 
and explosive gas of mines, and in 1700-1750 history records numerous 
explosions, especially in coal-mines. In was Volta who, in 1776, when studying 



METHANE 33 

the same gas, which is also evolved in marshes, showed that it differed 
from hydrogen, since in burning it requires double its volume of oxygen and 
forms carbon dioxide. In 1785 Berthollet proved that the gas is formed of 
carbon and hydrogen, and later Henry, Davy, and Berzelius determined its 
true composition. 

It occurs abundantly as exhalations from the earth near the Caspian Sea 
(sacred fires of Baku) and in the peninsula of Apsheron is used for heating 
purposes. 

At Pittsburg there are great wells of pure methane, and it is found also 
at Glasgow, in the Crimea, and also in Italy, at Pietra Mala (Bologna), in 
Ferrarese, in Piacento (Salsomaggiore), &c. It always occurs in coal-mines, 
being formed from the coal by slow decomposition and remaining occluded 
in the coal under great pressure, together with carbon dioxide and nitrogen. 

It is invariably developed in marshy places, where there is organic matter 
putrefying under water. It is found in the gas of the intestines of man and, 
still more, of the ruminants (about 50 per cent. CH 4 ), being produced by the 
action of enzymes on the cellulose of vegetable matter. Illuminating gas 
contains up to 40 per cent, of it. 

PROPERTIES. It is one of the permanent gases (vol. i, p. 28) ; it 
liquefies at 164 and solidifies at 186. It has no colour or taste, but 
a faint garlicky odour. It dissolves slowly but appreciably in fuming sul- 
phuric acid, but only very slightly in water (0-05 per cent.). It is readily 
inflammable and burns with a faintly luminous flame ; mixed with oxygen 
it forms a detonating mixture (inflammable at 667, whilst the mixture 
with ethane inflames at 616 and that with propane at 547), the maximum 
effect being obtained with 1 vol. of methane and 2 vols. of oxygen 
(CH 4 + 20 2 = C0 2 + 2H.JO). 1 Mixed with air, it forms the firedamp of 
coal-mines, which is very dangerous owing to its explosibility, 2 although it is 
not poisonous since miners can withstand an atmosphere containing 9 per cent, 
of methane ; if there is not more than this proportion, it produces a kind of 
pressure at the forehead, which ceases immediately on breathing pure air. 

By an electric charge or in a red-hot tube, it decomposes into carbon and 

1 Explosive gas mixtures (Teclu, 1907) : 







Minimum effect 






With excess 


With deficit 




Vols. 


Vols. 


Vols. 


100 volumes of air + hydrogen 


40 


170 


8-10 


, + methane 


10 





3-6 


, + coal gas . 


17-20 


31 


4-7 


+ acetylene 


8-3 


130 


2-4 


+ ether vapour 


3-3 


8 


1-5 


, + alcohol vapour 


6-5 





3-4 



2 Since the methane is occluded under great pressure between the layers of coal, its development and hence 
also the danger is greater when the atmospheric pressure diminishes or when the temperature rises. To prevent 
explosions of firedamp, the miners use the Davy lamp (vol. i, p. 377). Considerable danger of explosion more 
often exists in mines owing to the coal dust suspended in the air of the galleries and behaving Jike a pyrophotic 
substance (vol. i, p. 174) ; as a precautionary measure, air is continually circulated through the galleries by powerful 
fans, and the air and the walls are moistened by means of pulverisers. Hardy has constructed an apparatus which 
allows of the quantity of methane being determined from the sound produced by the mixture of air and methane 
in traversing an organ pipe. Mines containing much dust are dangerous even if the atmosphere is moist and the 
Davy lamp is used, since the particles of coal passing through the gauze into the lamp may issue in a red-hot 
condition. When mines are being excavated, safety explosives (which see) are used to avoid fires and explosions. 
Sometimes the coal ignites in certain parts of the mine ; in such cases, work is not suspended, but these parts are 
isolated by walls and if the fire becomes threatening, recourse is had (usually with success) to the sealing of the 
mine and subsequent inundation with water or filling of the galleries with carbon dioxide. When an explosion 
occurs in a mine, a large amount of carbon monoxide is formed which poisons the workers, who can, however, 
sometimes be rescued if they can be made to breathe, sufficiently promptly, under a bell containing compressed 
air (Mosso's Method ; vol. i, p. 175). 

n 3 



34 ORGANIC CHEMISTRY 

hydrogen, and a few unsaturated hydrocarbons, with traces of benzene and 
naphthalene. 

PREPARATION IN THE LABORATORY. Besides by the general 
methods given above, methane is formed by passing a mixture of carbon 
monoxide or dioxide with hydrogen over reduced nickel (catalyst) heated at 
250 (Sabatier and Senderens) : CO + 3H 2 = H 2 + CH 4 . Attempts have 
recently been made to put this method on an industrial basis, by transforming 
the carbon monoxide and dioxide of water-gas into methane (Ger. Pat. 
183,412). Pure methane is formed by passing a mixture of carbon 
disulphide vapour and hydrogen sulphide over red-hot copper (Bert helot) : 
CS 2 + 2H 2 S -f 8 Cu = 4 Cu 2 S + CH 4 ; also by treating aluminium carbide 
with water : C 3 A1 4 + 12H 2 O = 4A1(OH) 3 + 3CH 4 . 

In the laboratory it is usually prepared from an intimate mixture of one part of crys- 
talline sodium acetate with four parts of soda lime (or better, with four parts of baryta or 
with a mixture of anhydrous sodium carbonate and dry powdered calcium hydroxide). 
This is heated in a retort or in a hard glass tube until gas begins to be evolved, the tem- 
perature being then kept constant. As impurities, it contains a little hydrogen and 
acetylene, so that, before collecting the methane, the gas is passed over pumice moistened 
with concentrated sulphuric acid. 

Chemically pure, it can be obtained, by the general method, from zinc ethyl and water. 

INDUSTRIAL USES. For several centuries, the inflammable gases issuing from the 
earth and from petroleum have been utilised at Baku for heating lime-kilns. In North 
America, as far back as 1821, these natural emanations were used as illuminating gas. 
The most important discoveries, made at Pittsburg in 1882, resulted in 98 per cent, of 
the American production being obtained from this source in 1900 ; after 1905, the wells 
of Louisiana also acquired importance. The utilisation of the gas at the present day 
is carried out rationally and on a vast industrial scale, the gas (issuing from suitably 
constructed wells) passing to large gasometers which distribute it directly to over 500 
factories and 40,000 houses, where it is employed for power, heating, and lighting (with 
the Auer mantle), the price being about 3^ cents per cubic metre. In Canada, 400 wells 
are being used, giving, in 1907, gas of the value of 120,000. In England, wells have 
been sunk since 1900 which yield 400,000 cu. metres of gas per day. The spring at 
Wels, in Austria, which gave 57,000 cu. metres of gas per day in 1894, yielded only 500 
cu. metres in 1901. The gas utilised in the United States of America represents the 
following values in pounds sterling : in 1882, 40,000 ; in 1890, 1,400,000 ; in 1894, 
2,800,000 ; in 1899, 4,000,000 ; and in 1906, 9,600,000. These gases have the sp. gr. 
0-624-0-645, and a calorific value of 9000-10,000 cals. per cu. metre. The composition 
varies between the following limits : CH 4 , 80-95 per cent. ; H, 0-5-1-5 per cent, (some- 
times 15 per cent.) ; C 2 H 4 , 0-3-4 per cent. ; CO, 0-0-6 per cent. ; C0 2 , 0-3-2-5 per cent. ; 
0, 0-35-0-80 per cent. ; N, 0-5-3-5, together with traces of H 2 S. The amounts of natural gas 
used at Baku were 46-5 million cu. metres in 1905, 96-3 million in 1906, and 117 million 
in 1907, the composition being: C0 2 , 3-3-8 per cent. ; C,,H W , 1-2-2-6 per cent. ; 0, 7-7-6 
per cent. ; CH 4 , 54-8-60-2 per cent. ; H, 13-58-0-8 per cent. ; and N, 20-4-25 per cent. 

The gas which is used at Salsomaggiore (Piacenza) for public lighting purposes and which 
issues from the earth together with petroleum and saline waters containing iodine, has a 
specific gravity of 0-692, and the following composition (Nasini and Anderlini, 1900) : 
CH 4 , 68 per cent. ; C 2 H 6 , 21 per cent. ; heavy hydrocarbons, 1 per cent. ; N, 8 per cent. 
In Italy, 1 ,520,000 cu. metres of these gases, of the value 2280, were used altogether in 
1902, 6,737,500 cu. metres in 1908, and 8,270,000 cu. metres, of the value 8760, in 1909. 

Important sources of these gases have been recently discovered in Hungary, England (at 
Heathfield a well gave as much as 500,000 cu. metres per day), and in Denmark (since 1872). 

ETHANE, C 2 H 6 

This gas is found dissolved in crude petroleum and is one of the principal constituents 
of the North American gas-wells of Delamater, near Pittsburg. 

It is a gas which can be liquefied at by means of a pressure of twenty-four atmo- 
spheres and then has a sp. gr. 0-446 ; at the ordinary pressure it becomes liquid and boils 



PROPANE, BUTANES, PENTANES, ETC. 35 

at 84 and is solid and melts at -172. It is almost insoluble in water ; 1 vol. of 
absolute alcohol dissolves 1^ vol. of it. It burns with, a faintly luminous flame, and is 
more readily soluble than methane. In the laboratory it is prepared by the general 
methods already given (p. 32). 

PROPANE, C 3 H 8 (METHYLETHYL, CH'C 2 H 5 or 
DIMETHYLMETHANE, CH 2 (CH 3 ) 2 ) 

This is a gas like ethane and becomes liquid at - 44, or at under five atmospheres 
pressure, the liquid at having a sp. gr. 0-535 ; it solidifies and melts at 45. It is 
slightly soluble in water, and absolute alcohol dissolves 6 vols. of it. With water under 
pressure and at temperatures below it forms a solid hydrate, which decomposes at 
+ 8-5. The illuminating power of propane is about 1^ times that of ethane. It is 
best prepared, in the laboratory, by reducing isopropyl iodide by means of the copper- 
zinc couple, or by reducing acetone or glycerol with hydriodic acid : 

C 3 H 5 (OH) 3 + 6H = 3H 2 + C 3 H 8 or CH 3 -COCH 3 + 4H = H 2 + C 3 H 8 . 
glycerol acetone 

BUTANES, C 4 H 10 (Two Isomerides) 

(a) Normal Butane, CH 3 CH 2 ' CH 2 CH 3 (diekhyl), is a gas which liquefies at + 1, 
and at has a sp. gr. 0-600. It is found in Pennsylvanian petroleum, and is prepared 
in the laboratory by the ordinary methods (p. 32). 

PTT 

(b) Isobutane, CH 3 CH-c^Tj 3 (trimethylmethane or methylpropane), is a gas which 

t^ 3 

becomes liquid at 115 ; it is contained in petroleum and is prepared by the usual 
methods in the laboratory. 

PENTANES, C 5 H 12 

These hydrocarbons are found especially in the petroleum products boiling a little 
above 0, and are placed on the market under the names of rhigolene and cymogen for 
anaesthetic purposes and for the manufacture of artificial ice. The three isomerides 
predicted by theory are known : 

(a) Normal pentane, CH 3 - [CH 2 ] 3 'CH 3 , is a colourless, mobile liquid boiling at + 37-3, 
having a sp. gr. 0-454 at 0, and solidifying only at about 200 ; it is hence used for 
making low-temperature thermometers, and as a lubricant in the Claude liquid air 
machine (vol. i, p. 298). It occurs abundantly in Pennsylvanian petroleum. 

(b) Isopentane, CH 3 CH CH 2 CH 3 (methyl-2-butane or ethylisopropyl), is a light 

CH 3 

colourless liquid boiling at 30-4, and having a sp. gr. 0-622 at 20. It is found in large 
quantities in petroleum, and can be prepared artificially from isoamyl iodide by the 
ordinary methods (p. 32). 

pTT PTT 

(c) Tetramethylmethane, riT] 3 ^>V<^ nri 3 (dimethyl-2-propane), ie found in the gases from 



petroleum, and is liquid at + 9 and solid at 20. It can be obtained in the laboratory 
either by chlorinating acetone, CH 3 'CO'CH 3 , by means of phosphorus pentachloride 
and treating the dichloropropane thus formed with zinc-methyl : 

CH 3 Cl CH 3 _ CH 3 CH 3 

CH 3 > <Cl 4 ^CHg lU * + CH 3 ^ ^CH-j' 

or from tertiary butyl iodide by the action of zinc methyl : 

.CH 3 , 3 ,, , 
Zn < = 2 > < 



CH 3 .CH 3 , CH 3 

CH 3 I + Zn <CH 3 = 2 CH 3 3 



The constitutions of acetone and tertiary butyl iodide having been determined (see later), 
that of tetramethylmethane is fixed. And since the reduction of butyl iodide yields 
isobutane, the constitution of the latter is proved. 

HEXANES, C 6 H 14 

The five isomeric hexanes which should exist are all known (see Table, p. 31 )_ They 
are found particularly in petroleum ether, gasolene, and ligroin (i.e. in the portions of 



36 ORGANIC CHEMISTRY 

petroleum boiling below 150), together with heptanes and octanes. They are formed also 
from shaly coal like cannel coal and boghead. 

HIGHER HYDROCARBONS 

These are very numerous and are found in petroleum and in its residues (vaseline, 
paraffin, &c.) ; they distil unchanged (after C^) only in a vacuum, the boiling-point 
being thus lowered by about 100. 

Many of these higher normal hydrocarbons were prepared synthetically by Krafft 
by reducing the corresponding fatty acids, alcohols, and ketones. 

HEPTACOSANE, C 27 H 56 , and HENTRIACONTANE, C 31 H 64 , are found in beeswax 
and in American tobacco (about 1 per cent.), the former being also found in soot. 

HEXACONTANE, C 60 H 122 , is the highest term of the paraffin series to be prepared 
synthetically by Hell and Hagele in 1889 by condensing 2 mols. of myricyl iodide, 
C 30 H 61 I, by fusion with sodium, which removes the iodine as Nal. It melts at 102, 
is slightly soluble in alcohol or ether, and distils, to some extent unchanged, in a 
vacuum. It has probably the normal structure and thus forms the longest carbon 
atom chain as yet prepared synthetically. 

Some of the saturated hydrocarbons of the aliphatic series have important 
practical applications, especially as sources of light and heat. In illuminating 
gas are found the gaseous members, in petroleum the liquid, and in paraffin 
the solid ones. 

A brief account of the industrial treatment of these three products will 
now be given. 

ILLUMINATING GAS 1 

Illuminating gas and the other products of the dry distillation of coal vary in com- 
position with the nature of the coal employed. In gas manufacture, account has to be 
taken of the value of the by-products : coke, tar, ammonia, &c., which sometimes con- 
tribute largely to the cost of manufacture. So that mixtures of coal are used which 
give good coke, the luminosity of the gas from certain coals being supplemented by mixing 
with others rich in hydrogen and fats, such as some of the very expensive English coals, 
like cannel coal, boghead, various shaly coals, &c. In general, coals used for making 
gas have compositions varying between the following limits : C, 78-85 per cent. ; 
H, 5-8 per cent. ; O, 6-13 per cent. ; N, 1-2-1-9 per cent. ; and S, 0-1-2 per cent., a 
high content of sulphur being harmful ; they should leave little ash on burning, and 
preference is given to those containing considerable quantities of volatile products. The 
more hydrogen there is, the greater will be the useful yield, since every kilogram of hydro- 
gen can gasify 4-5 kilos of carbon (according as more or less methane, ethylene, &c., is 
formed). Gas-coal giving good coke contains more than 15 per cent, of volatile products 
and less than 35 per cent. 

1 History. This industry began with the nineteenth century, its apotheosis being reached at the end of that 
century with the application of the incandescent gas-mantle. From the year 900 the Chinese have employed 
petroleum vapour, distributed by wooden pipes, for lighting purposes. It was, however, only in 1739 that 
James Clayton, in investigating the causes of the emanation of inflammable gas often occurring in the Lancashire 
mines, heated coal in closed vessels and collected the gas (illuminating gas !) developed in large bladders. In 
1767, Watson, in laboratory experiments on a small scale, obtained gas, ammonia, and coke by the distillation of 
coal. This was the time when coke was beginning to be employed in metallurgical operations, and in 1786 Lord 
Dundonald used the gas from the coke furnaces to light his house, and Pickel lighted his laboratory with the gas 
formed on distilling bones. More important trials were, however, made in England by W. Murdock, for the 
illumination of large works by distilling coal. Helped in his undertaking, first by Watt, the inventor of the steam- 
engine, and afterwards by his pupil Clegg, he succeeded in 1805 in extending lighting by gas to many establish- 
ments. The distillation of wood was studied by the engineer F. Lebon, in France ; and in 1799, a patent was taken 
out " for a new method of employing combustibles more efficiently, for heating or lighting, and of collecting the 
various products." Some days later, all Paris was admiring the gas-lamp which Lebon used to illuminate the gardens 
of the Hotel Seignelay. Probably Lebon did not then foresee the wonderful development which was to take place 
in gas lighting in the nineteenth century or dream of the monument to be erected to him many years later in his 
native town, Chaumont, or of the statue which was dedicated to him in Paris in 1905. 

It was when the use of large plant was attempted for lighting by gas that technical difficulties cropped up, 
inconveniences which were negligible on a small scale becoming insurmountable in the case of large works. It was 
already noticed that the new illuminating gas burned with a rather sooty flame and disseminated unpleasant 
odours, whilst in the works the piping often became obstructed owing to solid distillation products being carried 
by the gas. If, in addition, we consider the popular prejudice to any innovation, aggravated by the fantastic 
propaganda of certain scientific men, especially in France, who exaggerated the danger of explosion, it is easy to 
conceive how unpromising the conditions of this industry were up to 1812. To Clegg is due the elimination of 
the main technical difficulties, the tarry matters carried along by the gas being removed by means of a number of 



ILLUMINATINGGAS 37 

The oxygen present in coal gives rise to larger or smaller quantities of carbon dioxide 
and monoxide, and it cannot be denied that the monoxide is a powerful poison. Only 
10-15 per cent, of the nitrogen present in the coal is transformed into ammonia, 20 per 
cent, being found in the gas and 60 per cent, in the coke, whilst 2-3 per cent, forms hydro- 
cyanic acid and cyanides in the gas and tar. Moisture in the coal is harmful, since water 
causes an increase in the amount of carbon dioxide in the gas and also absorbs heat for 
its evaporation. 

In order to judge of the value of the coal, distillations are carried out, in gasworks, 
in small laboratory retorts containing a weighed quantity of coal and heated at a very 
high temperature (900 and even higher) ; the gas and vapours are washed in bottles, 
first with lime-water and then with lead acetate, the pure gas being collected in a cylinder 
over mercury, so that it can be measured and its composition and illuminating power 
investigated. To judge of the practical value of a coal, use is made of the product of 
the yield of gas (that is, the number of cubic metres from 100 kilos of coal) and its candle- 
power. For any given coal, this product is almost constant ; increase of the temperature 
of distillation resulting in a greater yield of gas, but of a lower illuminating power. 
Naturally this rule holds only between certain limits of temperature, which are never 
exceeded in practice. 

Of various coals, the best is that which gives the highest value for this product, but 
account must also be taken of the yields of coke, ammonia, and tar, and of the specific 
gravity of the gas. 

The temperature of carbonisation varies with the nature of the coal and, in general, 
with fatty coals (bituminous) the evolution of gas begins at 50, and at a red heat vapours 
of liquid products pass over ; at a higher temperature, gaseous products predominate. 

The most convenient temperature usually lies between red heat (cherry-red) and 
yellowish white heat. In general, after an hour's heating (with a furnace at 1400), the 
coal in the retort reaches 400, after three hours 950, and after five hours 1075. On 
heating 1000 kilos of English coal at different temperatures the following results are 
obtained : 

At red heat At bright orange red 

(a) Gas obtained (cubic metres) . . 234 . . 340 

(b) Candle-power ... . 20-5 . . 15-6 

(c) Candles per 1000 kilos = a x b . . 4800 . . 5300 

(d) Composition : Hydrogen . . . 38-1 % . . 48 % 

Carbon monoxide . . 8-7 % . . 14 % 

Methane . . . 42-7 % . . 30-7 % 

Heavy hydrocarbons . 7-6 % . . 4-5 % 

Nitrogen . . . 2-9% .. 2-8% 

Gas prepared at a higher temperature has a lower calorific power. 

cooled tubes, and further purification being effected by lime, the gas being then collected in large gasometers, 
from which it was distributed by pipes to the consumers. Thus, it became possible in 1813 to light part of London 
with coal gas, and in 1815 Winsor illuminated certain quarters of Paris.^ 

Nobody on the Continent dared attempt a similar industry ; everybody was distrustful, not foreseeing its 
great future and being frightened by the technical difficulties which met this, the first great chemical industry, 
for many years confined to England. It was in this country that it underwent the most rapid extension and per- 
fection (in 1823, fifty-two towns were lighted by gas), the scientific and practical men giving it their entire support. 
In 1810 a powerful English company was founded by Clegg and became later the famous Imperial Continental 
Gas Association, which with a capital of 2,000,000 in 1824, 3,500,000 in 1874, 3,800,000 in 1897, and 5,000,000 
in 1908, was formed with the view of undertaking the lighting of the principal European towns. Even to-day 
many towns are still pledged to contracts, as yet unexpired, with the great English companies. London itself, 
within the last few years, has found the greatest obstacle to the introduction of electric lighting in contracts with 
gas companies which have already made fabulous profits. 

In Germany, the first small gas-plant was that of Lampadius in 1816, used for his own establishment, extension 
being subsequently effected as a result of the work of Flashoff and Dinnendhal. At Berlin the first attempt was 
made in 1829 ; then followed Hanover, and in 1884, 557 German towns were lighted by gas, the annual consump- 
tion of coal being 1,700,000 tons. In Austria the first plant was erected in 1818 by Prechtl. In America, Baltimore 
was illuminated by gas in 1806, Philadelphia in 1822, and New York in 1834. At Milan gas lighting was introduced 
in 1832. 

After 1870 all the principal populous centres and even the small towns were lighted by gas, all objection to this 
form of illumination having disappeared ; experience had shown that the expected terrible explosions of mixtures 
of gas and air did not occur and that the small accidents which did happen were not more serious than those occur- 
ring daily with paraffin lamps. The victory over petroleum, although furiously contested, was especially complete 
in the case of public lighting. 

To this success have contributed, most of all, the incessant improvements of methods of manufacture, wlvoh 
have resulted in the supply of a purer, more abundant, and more economical gas. 



38 ORGANIC CHEMISTRY 

The composition of gas varies also according as the heating is more or less prolonged. 1 
It will be seen that the diminution of luminosity is less proportionally than the increase 
in volume of the gas, and to-day the distillation is pushed to a temperature of 1100-1200, 
this resulting in greater (absolute, not relative) quantities of light, luminous hydrocarbons 
and of hydrogen being obtained. It is hence important to employ suitable mixtures of 
coals, so that these may be impoverished as much as possible at a high temperature, 
the relatively low luminosity being compensated for by the addition of special fatty 
coals, as already mentioned, and also, at the present day, of benzene. 

The duration of the distillation varies from 3 to 5 hours ; the extra amount of gas 
that would be obtained by heating further would be insufficient to make up for the cost 
of heating. 100 kilos of WestphaHan coal give about 71 kilos of coke, 4 kilos of tar, 
5 kilos of ammonia liquors, and 17 kilos (30-5 cu. metres) of gas ; loss, 3 kilos. 

The COMPONENTS OF ILLUMINATING GAS obtained from coal are 
very varied and can be embraced in three groups : (a) combustible diluents : 
H, CH 4 , CO ; (6) light-yielding gases and vapours : ethane, ethylene, butylene, 
acetylene, crotonylene, allylene, pentylene, benzene, toluene, xylene, thiophene, 
styrene, indene, naphthalene, acenaphthene, fluorene, propane, butane, pyri- 
dine, phenols ; (c) inert or "harmful impurities : C0 2 , NH 3 , HCN, CS 2 , COS, and N ; 
naturally the majority of these substances are present only in traces. 

The quantitative composition by volume of the gas usually varies between 
the following limits : C0 2 , 1-25-3-20 per cent. ; CO, 4-5-6-5 per cent, (for 
English coals, 6-9 per cent., and for German coals, occasionally 9-11 per 
cent.) ; H, 42-55 per cent. ; CH 4 , 32-38 per cent. ; N, 1-3 per cent. ; 0, 
0-0-5 per cent. ; aromatic hydrocarbons (benzene, &c.), 0-8-1-4 per cent. ; 
unsaturated hydrocarbons (ethylene, 2-2-5 per cent. ; acetylene, 0-1-0-2 per 
cent. ; propylene, 0-2-0-5 per cent., &c.) The specific gravity of gas varies 
from 0-350 to 0-500 (air = 1) and 1 cu. ft. of gas weighs rather more than 
half an ounce. 2 The calorific power of illuminating gas ranges, as a rule, 
from 4000 to 5000 cals. per cubic metre, thus producing the same heating 
effect as 3-43 kw. -hours. The illuminating power is discussed later. 

PROPERTIES OF ILLUMINATING GAS. In addition to the lighting 
power, for which it is mostly used, to the heating power which makes it a 
valuable source of mechanical energy for gas motors, to the relatively low 
specific gravity which renders it useful in aeronautics, attention must be paid 
to the explosive properties of illuminating gas when mixed with air (see p. 33), 
and to its poisonous properties even when present in only 2 per cent, by volume. 
Its poisoning effect is due especially to the carbon monoxide present, but also, 
to some extent, to other components. When the first symptoms of poisoning 
are observed, fatal consequerices can be prevented by vigorous respiration 
of pure air or, better, oxygen, while the use of compressed air according to 
Mosso's system also gives good results (vol. i, p. 175). 

RETORTS. Murdoch's first retorts were of cast iron, placed vertically in a furnace 
(Fig. 44), but as it was inconvenient to charge them Murdoch introduced inclined retorts 
(Fig. 45), which he changed later into horizontal retorts of cast iron (Fig. 46). 

1 Wright analysed the gas for three different periods, starting from the beginning of the distillation, the results 
being : 

After After After 

40 minutes. three hours. six hours. 

Per cent. Per cent. Per cent. 

H,S 0-4 0-78 0-38 



CO, 

CO . 

CH 4 . 

H . 

Heavy hydrocarbons 

N . 



2-08 1-34 0-59 

4-52 6-73 7-52 

56-46 37-46 14-61 

25-36 48-36 91-94 (?) 

8-51 3-13 2-78 

2-37 s 2-20 2-18 



1 By passing ordinary gas into a retort filled with coke at 1200" or a higher temperature, a new gas, deprived 
of heavy hydrocarbons, oxygen, and carbon dioxide, very poor in methane (6 per cent.), rather richer in carbon 
monoxide (7 to 8 per cent.) and very rich in hydrogen (up to 84 per cent.) is obtained. This new gas can be 
used for aeronautical purposes its specific gravity bein about 0-23 (Continental Gas fiesetttchaft, Dessau, 1910). 



GAS RETORTS 



39 



In 1820 J. Graf ton suggested the use of horizontal retorts of fireclay, since these resist 
heat better, cost less and last longer. The most convenient form was that with a Q -shaped 
or elliptical section (Fig. 47), and the most suitable dimensions for these horizontal 
retorts were found to be : width of the mouth, 43-53 cm., height at the middle, 31-38 cm., 
and length, 2-3 metres. One end was closed and the mouth was swelled at the edge, 






FIG. 44. 



FIG. 45. 



FIG. 46. 




which carried screws serving to fix the metal cover fitted with the delivery tube. These 
retorts were charged, according to their capacity, with 100-200 kilos of coal, broken into 
uniform - lumps. Various mechanical connections were devised to allow of the retort 
being charged and discharged rapidly and with the least expense for hand labour, and one 
of the best arrangements, with a battery of retorts placed in regenerator furnaces (see 
vol. i, p. 500), is that shown in Pig. 48. However, since 1890 it has become general in 
the principal European towns to use inclined retorts of elliptical section, which were 
suggested anew by Coze and are 
furnished with two mouths pro- 
jecting from the two ends of the fur- 
nace (double-ended or "through" 
retorts). When these are inclined 
at an angle of 32 and are charged 
automatically from above, the coal 
distributes itself in a layer of uni- 
form depth along the whole of the 
retort (Fig. 49). The gas-discharge 
tube is inserted at the lower mouth, 
which at the end of the operation 
is opened, the coke, while still hot, 
being completely and immediately 
discharged into an iron truck or 

on to a moving endless perforated FIG. 47. 

band, the pieces of coke remaining 

alight being sprinkled with water before being discharged on to the coke ground. Similar 
retorts are used with elliptical mouths ; the upper one is rather larger (63 cm. x 35 cm.) 
than the lower (57 cm. x 30 cm.), and the length is about 3-8 metres. At the present 
day they vary from this length up to 6 metres. 

The advantages of this system are shown by the following results, which refer to three 
batteries of fourteen (1) inclined and (2) horizontal retorts : 





Duration of the distillation . 

Charge per retort 

Number of charges per 8 hours 

Total coal distilled in 8 hours 

Cost of labour per 1000 kilos of coal 



Inclined 

3 hours 
165 kilos 
112 



Horizontal 

4^ hours 
152 kilos 

72 



18,500 kilos 11,000 kilos 



10 pence 



18 pence 



40 

The pressure in the interior of the retorts should be carefully regulated, since if it 
becomes too great, escape of the light gases and vapours readily occurs and the develop- 
ment of vapours and gases is slackened, the hydrocarbons, which remain for a long time 
in contact with the red-hot walls of the retort, undergoing further decomposition with 
deposition of graphite on the walls and liberation of hydrogen. In order to avoid these 
inconveniences the retorts are to-day put in indirect communication with aspirators or 
pressure regulators placed beyond the washing apparatus (scrubbers, &c.). 

The layer of coal in the retort should not be too deep, as otherwise the gases given off 
are decomposed on contact with the upper layers of hot coke. 

With the view of avoiding decomposition of the more luminous gases which are evolved 
principally at the beginning of the distillation, Bentrup (1903) proposed passing a con- 
tinuous current of water-gas (see vol. i, pp. 392, 393) into the retort to remove these 
products rapidly from contact with the hot walls of the retort ; the water-gas is produced 
in an adjacent retort also containing red-hot coke. 




As often happens in other fields of work, so also in the industries a return to older 
methods often offers advantages. Thus it appears at the present time that the vertical 
retorts again brought into use by Settle and Padfield are destined to supplant the inclined 
ones. In 1905 Dr. J. Bueb made works experiments with a battery of ten retorts, 4 metres 
in length, placed vertically in a furnace and provided with an upper aperture for charging 
and a lower one for discharging (that is, the furnace surrounds only the external vertical 
surface of the retort, which is heated by hot gases circulating through numerous channels, 
as shown in Fig. 50). In this way a larger charge (up to 500 kilos) is used, the luminous 
gases are not decomposed and the yield of gas is higher, as the temperature of the retort 
reaches 1300-1400 C. ; at the same time very little naphthalene is produced, the incon- 
venience caused by depositions of naphthalene in the cold parts of the pipes being thus 
avoided. In addition, the yield of ammonia is increased by 35 per cent., the separation 
of the tar is facilitated and the cost of labour diminished ; a less amount of a harder coke 
is obtained, and the quantity of tar is considerably decreased, while the production of 
gas is increased (Ger. Pat. 155,742). N 

Fig. 50 shows a double battery of Bueb vertical retorts, 4 metres high and slightly 
conical in shape, the wider mouth at the bottom. By means of the elevator A the coal 
is introduced into the hopper B C, whence it passes into the movable scoops D, which 



FURNACES 



41 



carry it to the retorts. At the end of the distillation (which lasts 7-8 hours) the coke is 
discharged into the metal hopper, F, and thence into the channel, G, where a band running 
on rollers carries the spent coke to the store. The gas issues at the top of the retort and 
by the tubes, E, passes into the hydraulic main, /, and so into the piping, L ; the tar 
and the ammonia liquors are discharged from the hydraulic main into the tube, M , leading 
to the depositing tank. 

In order to increase the yield of gas by 10-15 per cent, it has recently been proposed 
to. utilise the high temperature of the coke (1400 C.) remaining in the retorts at the end 
of the distillation to produce a certain quantity of water-gas by passing a current of 
steam in at the bottom of the retort for an hour. It cannot, however, be denied that by 
this wet process the proportion of carbon monoxide in the gas is increased. In any case 
total yields of 360 cu. metres of gas per 1000 kilos of coal have been obtained in this" way. 

The economy in labour effected by this retort is very'great, and it is calculated that, 
whilst with horizontal retorts every 
workman produces about 1600 cu. 
metres of gas per day, with the 
vertical retorts the amount reaches 
7000 cu. metres. 

From 1906 to 1910 furnaces with 
507 batteries of 5500 vertical re- 
torts, representing a total daily 
production of 2,200,000 cu. metres 
of gas, have been manufactured by 
one single firm at Dessau (for Berlin, 
Cologne, Zurich, Trieste, Geneva, 
&c.). 

In the working of these vertical 
retorts, which do indeed represent 
a marked advance on the Coze 
inclined retort, certain disadvan- 
tages have been observed, the coke 
formed being harder than the ordi- 
nary and not so well suited for 
domestic purposes ; whilst the gas- 
discharge tubes soon become 
obstructed with tarry matters so 
that they require cleaning every 
3-4 days ; distillation with steam 
during the last phase of the heat- 
ing relieves this inconvenience to 
some extent. By some the pro- 
duction of water-gas as described above is not regarded as advantageous, the same 
quantity of water-gas being obtainable more economically with special plant. 

A further and more recent modification consists in the use of chamber furnaces (similar 
to those for making metallurgical coke, see vol. i, p. 367). 

At Monaco in 1906 and at Vienna in 1909 inclined chamber furnaces were employed 
(Kopper system, Fig. 51). Coal from the hopper, 2, passes down an inclined plane and 
fills the chamber, 5 ; the gas is led into the trough, 1, the coke is discharged, by opening 
the large lower door with a crane, on to an inclined plane and so to the chain transporter, 6, 
and the gasogen, 8, passes the gas to the dust-chamber, 7, and then to the ascension pipes 
under the chambers ; 9 shows another battery of inclined chambers. With chamber 
furnaces a better gas is obtained with a less expensive plant and a decided economy in 
labour, the daily yield of gas per workman reaching 9000 cu. metres. A plant of this 
kind was finished in 1910 at Padua. 

With horizontal or inclined retorts the coal is heated for 4-6 hours ; with vertical 
ones, 12 hours ; and with chamber furnaces, 24 hours. 

FURNACES. Retorts were first of all heated by direct flame, but in this way the 
heat is inefficiently utilised ; then indirect heating by flues, just as for steam boilers, was 
tried, but the nearer retorts wore out very rapidly, so that later several retorts were placed 




FIG. 49. 



42 



ORGANIC CHEMISTRY 



in one furnace in direct contact with the hot gases, these being so interrupted and deviated 
that the surfaces of all the retorts were uniformly heated (Pig. 48). 

At the present time the use of the regenerator gas furnace (gasogen, see vol. i, p. 501 ) 
has become general, coke (usually waste) being employed, and, in countries where there is 







FIG. 50. 

little demand for tar, the latter being used as fuel by injection into suitable furnaces. 
The coke used to heat the furnaces represents about 25 per cent, or 30 per cent, of the 
total amount produced. In some works (e.g. at Turin since 1909) the heating of the 
furnaces is profitably effected by 9-10 per cent, of tar (on the weight of coal distilled), 
burnt in special gasogens. 

The wear of the furnaces and retorts is considerable, and their cost is calculated as 



PURIFICATION OF GAS 



43 



annual expenditure rather than as cost of plant, since they are sometimes remade or 
renovated twice a year. 

PURIFICATION OF GAS. The crude products obtained directly from the carbonisa- 
tion of bituminous coal cannot be used immediately for lighting and other purposes. The 
gas issues from the retorts at very high temperatures (up to 250), and it is evident that, 
as it gradually cools, various products separate, first of all those which are solid or liquid 
at ordinary temperatures. It is necessary to remove the tar, naphthalene, ammonia 
liquor, and the cyanogen and sulphur compounds by means of the following apparatus. 

HYDRAULIC MAIN. This is a wide circular or semi-circular pipe (diameter, 
30-60 cm.) of sheet-iron or cast-iron (Fig. 48 V), containing water and tar, and placed 
above the retorts so that the ascension pipes, R (12-18 cm. in diameter) from one battery 
of retorts dip into it, these pipes starting from the lower parts of the retorts and carrying 
off all the hot gas developed. The tubes, R, are sealed hydraulically by dipping into water 
in the hydraulic main, in which most of the tar and a little of the ammoniacal liquor 
condense. The hydraulic main falls slightly towards one end so as to facilitate flow of 
the tar to the store-tanks, in which it gradually becomes almost entirely separated from 
the ammonia liquors, being sold to the tar-distiller with a content of not more than 5 
per cent, of water at a price of about 17 pence per cwt. (lire 3,50 per quintal). 




FIG. 51. 

The still very impure gas, holding in suspension large numbers of tar drops which 
render difficult the condensation of the naphthalene and having a temperature of 
60-100 C. is gradually cooled to 12-15 C. by causing it to traverse a large iron pipe 
passing round inside the whole of the works and cooled by the air ; the gas then reaches 
a condenser formed either of a battery of long iron tubes (Fig. 52) sprryed outside with 
water, or of a series of three or four double-jacketed cylinders cooled inside and outside by 
the air, the gas passing into the jacket (Fig. 53) ; or the gas may be circulated round a 
number of narrow tubes through which passes a continuous stream of cold water (Fig. 54). 
The cooling thus effected is gradual, and the separation of the naphthalene and tar is 
more complete, while there is no danger of stoppages from the naphthalene ; in winter 
the gas enters the cooler at 50-60 C. and leaves at 5-10 C., while in summer it enters at 
60-70 C. and emerges at 30-35 C. At the bottom of these tubes is found a deposit 
of tar which is discharged into tanks and of ammonia liquors at 7-8 Be. The 
consumption of water in these coolers is from 3-4 cu. metres per 24 hours per 1000 
cu. metres of gas. 

If an obstruction of naphthalene occurs at any point, the pressure indicated by 
manometers placed along the tubes shows an increase at that point. 

The gas issuing from the condensers still contains suspended tar, which it is necessarj 
to separate. To this end serves Audouin and Pelouze's tar-separator, shown in Fig. 55. 
The gas passes along the tube B, which opens into a perforated double-walled bell, D, the 
pressure in which is regulated by a compensating weight and pulley, G. The bell is 
partially sealed hydraulically and rises more or less, leaving open a greater or less number 
of apertures, according to the pressure of the gas. The gas is thus subjected to a kind 



44 



ORGANIC CHEMISTRY 



of filtration through small orifices, the fine drops of tar being condensed into larger drops, 
which separate and collect in E, whence the excess is run off at F. The gas thus purified 
from tar passes by the tube C to the ammonia-condensing apparatus. The tar-separator 
should not be kept too cold (12-15 C.) 

NAPHTHALENE SEPARATORS. Naphthalene is a product of the condensation 
by heat of the heavy hydrocarbons of the gas. It is difficult to imagine how pertinaciously 
gas carries through all the purifying operations considerable quantities of naphthalene 
suspended in it, and how slowly this naphthalene is deposited in town mains, ultimately 
stopping them and causing great inconvenience and expense to consumers and manu- 
facturers. 

In 1899 Bueb, on the basis of former experiments of Young and Glover, succeeded in 
avoiding this trouble to a great extent by passing the gas (first washed with water in 

the " Standard " washer-scrubber to separate the 
ammonia) into a drum similar to the "Standard" 
(see below), but with three independent chambers in 
which the gas is washed with anthracene oil of 
medium density (prepared by the distillation of tar 
and having a b.pt. 350-400 C.), which dissolves 





FIG. 52. 



FIG. 53. 



FIG. 54. 



and fixes almost all the naphthalene. When the oil of the first chamber is saturated it 
is removed, and that of the second chamber passes into the first and that of the third 
into the second ; the third chamber is charged with fresh oil, containing 4 per cent, of 
benzene in order to avoid loss of light-giving products from the gas. The anthracene oil, 
saturated with naphthalene (25 per cent.) can be utilised as such, or mixed with 
ordinary tar. 

According to U.S. Pat. 968,509 of 1910, naphthalene can be separated by bubbling 
the gas through an aqueous solution of picric acid, this giving rise to an insoluble naphtha- 
lene picrate, from which the naphthalene can be distilled by means of steam, the picric 
acid being left. 

SEPARATION OF AMMONIA. The washing of the gas for the purpose of removing 
the ammonia may be effected by ordinary water, which has a great affinity for ammonia, 
or by the dilute ammonia liquors from the hydraulic main (1-2 Be.), but not with 
that from the condenser, which is too concentrated (7-8 Be.). The most common 
form of apparatus used for this washing is the scrubber or, better still, the " Standard " 
washer - scrubber. 

SCRUBBERS are usually formed of a series of coke-towers through which water 
trickles (Fig. 56). The gas that enters the bottom of the first tower is washed with dilute 
ammonia, condensed in succeeding tower?, and when it reaches the last tower it is washed 



PURIFICATION OF GAS 



45 



with pure water which dissolves the last traces of ammonia and can be used subsequently 
for the first tower, from the bottom of which it is carried off, rich in ammonia, by small 
syphons. These towers, which are of cast-iron sheets, are joined in twos or threes in 
such a way that the gas is conducted from the top of the first tower to the bottom of the 
second, and so on. The interior may "be fitted simply with water pulverisers, or it may be 
filled with coke, chips of wood, broken bricks, or, what are more efficient, vertical bundles 
of sticks, or of corrugated and toothed iron sheets. 

Scrubbers are 1-3 metres in diameter and 4-20 metres in height. A maximum produc- 
tion of 1000 cu. metres of gas per 24 hours requires 5-6 cu. metres of scrubber, the gas 
taking 8-10 minutes to pass through. Before entering the scrubber the gas contains 
200^400 grms. of ammonia per 100 cu. metres, whilst afterwards this volume contains 
only 1-10 grms. 

The "STANDARD " washer-scrubber consists of a large horizontal fixed cylinder of 
iron-plate, divided into seven chambers (Fig. 57). This cylinder is traversed by a rotatable 





FIG. 55. 



FIG. 56. 



axis carrying seven paddles of almost the same diameter as the chambers and each consisting 
of two large metal plates to which are fixed the ends of superposed wooden laths with 
spaces, not exactly superposed, between (Fig. 58). These paddles rotate with the axis 
and dip into water which fills the chambers to about one-third of the height of the cylinder. 
The pure water enters chamber VII at a and passes from chamber to chamber until it 
reaches the first, the walls separating the chambers being successively lower. The gas 
to be purified moves in the opposite direction, entering chamber I, and passing between 
all the laths of the paddle from the centre to the periphery, then descending to the centre 
of the next paddle in chamber II as shown by the arrows, 4 and 5, again issuing at the 
periphery, passing into chamber III, and so on. In this way the gas is perfectly washed 
and loses also part of its C0 2 and H 2 S. The water leaves chamber I with a density of 
7-8 Be. 

At Monaco the ammonia is eliminated in the dry way by passing the gas over super- 
phosphate, which fixes it and then serves as an excellent fertiliser (with 7-8 per cent, of 
nitrogen) : 1000 kilos of superphosphate are sufficient to purify 32,000 cu. metres of gas 
(with 3 per cent, of NH 3 ), the small quantity of thiocyanate (0-5-2-5 per cent.) which it 
contains having no injurious action on [plants. N. Caro (U.S. Pat. 952,560, March 22, 



46 



ORGANIC CHEMISTRY 



1910) cools the gas from coke manufacture to 20 and then passes it through a solution 
of ammonium sulphate of 29-35 Be. containing 5 per cent, of free sulphuric acid ; 
ammonium sulphate gradually crystallises out and the gas passes off free from ammonia. 
Generally, however, ammoniacal liquors are distilled with lime and the ammonia fixed 
with sulphuric acid (see vol. i, p. 323). Every ton of coal carbonised yields 10-12 kilos 
of commercial ammonium sulphate. 

FINAL AND COMPLETE PURIFICATION OF GAS. After the ammonia, the 
following gases must be removed : H 2 S, CO 2 , HCN, CS 2 , thiocyanates, sulphur derivatives 
of hydrocarbons, &c. This is especially important with H 2 S and other sulphur compounds 
(about 1-1-5 per cent, by volume of the crude gas), since they partly burn, forming SO 2 , 
and partly escape unaltered from the gas-jets, decorations, metal-work, and paintings being 
discoloured ; also the poisonous properties of these compounds are considerable, the crude 
gas containing 0-1-0-25 per cent, by volume of hydrocyanic acid. The test employed by 
large consumers to detect hydrogen sulphide is very rigorous and is made with lead 
acetate paper, which blackens on prolonged exposure to impure gas. 

The final purification of gas has been in use ever since the beginning of the industry. 
In 1806 Clegg purified gas partially by passing it through milk of lime, but such large 





volumes of liquid were required that their preparation was difficult and the purification 
was not complete. He then proposed the use of powdered slaked lime, which fixes carbon 
dioxide, as well as many sulphur compounds, forming calcium sulphydroxide, OH-Ca-SH ; 
but if much C0 2 is present the sulphydroxide is decomposed and SH 2 regenerated. In 
1840 Mallet suggested the use of manganese oxide, which fixes H 2 S more readily, but this 
method did not give good results. 

At the present time use is largely made of the so-called Laming mixture, which is 
prepared by mixing 160 parts of lime, 180 of sawdust and 30 of ferrous sulphate dissolved 
in scarcely sufficient water to moisten the mass ; it is kept turned over for some days in 
the air, until it becomes brown owing to the conversion of the ferrous sulphate into ferrous 
hydroxide and then ferric hydroxide, calcium sulphate being formed at the same time. 
The latter fixes the ammonium salts (such as have not been already separated), while the 
ferric hydroxide fixes hydrogen and other sulphides : 2Fe(OH) 3 + 3H 2 S = 6H 2 O + F 2 S 3 
(iron sesquisulphide), and also forms iron thiocyanate from hydrocyanic acid (i.e. from 
ammonium cyanide) and thiocyanates, the excess of lime removing the carbon dioxide. 

The whole of the iron present does not take part in these reactions, but when the 
mixture is exhausted it can be regenerated by further exposure and turning in the air for 
two or three days, the whole of the sulphur being liberated : 

Fe 2 S 3 + 3O + 3H 2 O = 2Fe(OH) 3 + 3S. 

The mass can be thus revivified and used again some ten or more times, after which 
it is rejected. But this product contains 35-50 per cent, of free sulphur, 10-15 per cent, 
of Prussian blue, 1-4 per cent, of ammonium thiocyanate and 1-4 per cent, of ammonium 
sulphate, and nowadays the free sulphur is often extracted by carbon disulphide, while 



GAS PURIFIERS 



47 



from the residue cyanides and f errocyanides can be obtained ; or the mass is first extracted 
with water to obtain the cyanides and the ammonium sulphate, the dried residue being 
used in place of pyrites in the manufacture of sulphuric acid (see vol. i, p. 650 ). 1 

As will, however, be seen, the lime takes no part in the separation of the hydrogen 
sulphide (but only in the fixation of the C0 2 ), so that, in the last few years, Laming 
mixture has been replaced by hydrated ferric oxide (minerals such as limonite, &c.) mixed 
with a little lime and sawdust ; by using natural oxide of iron alone, the reaction becomes 
very energetic, the mass being sometimes almost ignited. These mixtures give good 
results and are placed on the market under various names : Deicke mixture with 66 per 
cent. Fe 2 O 3 and Lux mixture with 51 [per cent. Fe 2 3 . They are' made .by -mixing the 
powdered iron residues from the working of bauxite with soda and fusing in a furnace, 
the silicates which have become soluble being then extracted by water and the remaining 
ferric hydroxide mixed with double its volume of sawdust : 1 cu. metre of this " Lux " 
mixture, at an initial cost at the Ludwigshafen factory of about 15s. per ton, purifies more 
than 10,000 cu. metres of gas, whilst natural Silesian ferric oxide costs 8-1 2s. per ton. 

The purifying mixture is arranged in several layers, all of which are traversed by the 
gas (Fig. 59). The cover to the chamber is water -sealed (Fig. 60), and can be easily raised 
by means of a crane when the mass is to be removed for regeneration. It is simpler to 





FIG. 59. 



FIG. 60. 



use a single layer of the mass 50-60 cm. deep, the gas'being introduced at a greater pressure ; 
it is then easier to discharge the exhausted mass through an aperture in the base of the 
reservoir. 2 At the present day the costly labour required for the regeneration is avoided 
by not emptying the reservoir, a rapid current of air or oxygen being passed through for 
several hours, this operation being rapid, complete and economical ; in some works, how- 
ever, the mass is kept always oxidised by mixing about 2 per cent, of air with the gas 
before passing it into the chamber. 

1 The cyanogen compounds of the crude gas which are formed from ammonia by the action of heat and cause 
corrosion of ironwork are best separated in the wet way by Bueb's process (Ger. Pat. 122,280, May 1900), in 
which, before being freed from ammonia, the gas is passed into a kind of " Standard " containing ammonia 
and a ferrous sulphate solution of 20 B6. By this means, ferrous sulphide first gradually separates 
[FeSO 4 + (NH 4 ) 2 S = FeS -i- (NH^SOj], and is then slowly converted, under the action of ammonia and 
hydrocyanic acid, into an insoluble mass composed of ammonium ferrocyanide, (NH 4 ) 4 FeCy,, and of a ferrous 
ammonium ferrocyanide, (NH),Fe(FeCy,) a . This sludge, which contains all the cyanides, corresponding in 
amount with 15 to 20 per cent, of crystallised potassium ferrocyanide, is heated to render insoluble the small 
quantity of cyanide still undissolved and to drive off ammonium carbonate, and is then passed to filter-presses ; 
the nitrate is utilised for the extraction of ammonium sulphate, while the cyanide residue is heated with lime 
to give ammonia and calcium ferrocyanide, a solution of the latter yielding pure sodium ferrocyanide when 
treated wit h sodium carbonate. This process has given satisfactory results in the Turin gasworks and many 
others in Europe, but is already beginning to lose its importance, owing to the discovery of new synthetical 
methods of preparing potassium cyanide (vol. i., p. 435). 

a This exhausted mass is often utilised for the sulphur it contains, while in many other cases the cyanides, 
thiocyanates, ferrocyanides, &c., are extracted (see vol. i, p. 650) ; it is also sometimes used on roads as a weed- 
killer cyanides having a poisonous action on plants and, finally, it has been proposed as a nitrogenous fertiliser 
(itcontainsonthe average 5-6 per cent, of nitrogen, one-tenth of which is in the formof ammonia and the rest as 
cyanide), but it must be spread on the naked land two or three months before sowing takes place, as it takes time 
to decompose and become innocuous to vegetation. 



48 



ORGANIC CHEMISTRY 



After purification the gas passes through large meters to the gasometers, after traversing 
a glass bell-jar in which is suspended a strip of moist lead acetate paper for the detection 
of H 2 S. 

In order to diminish the quantity of carbon monoxide in gas, L. Vignon (1911) proposes 
to heat it over lime and with steam, by which means non-poisonous hydrocarbons are 
formed. 

EXHAUSTERS. To regulate the pressure of the gas in the retorts and other parts 
of the plant, exhausters are placed between the condensers and the tar separators, or even 
after the scrubbers. Sometimes a bell-aspirator is used, consisting of a bell immersed 
in water and capable of being raised and lowered mechanically, and thus, by means of 
suitable valves in the lid, of acting both as exhauster and as compressor. There are also 
piston exhausters, others similar to exhaustion pumps working by eccentrically moving 
blades (Beale type), &c. The so-called Korting injectors, which make use of steam-jets, 
are also used as exhausters. 

PRESSURE REGULATORS. Since the development of gas cannot be regulated 
in the retorts, whilst the working of the exhausters is uniform, there may at certain times 

be an excess pressure generated, espe- 
cially if the exhausters cease working 
owing to damage. Hence, so-called 
pressure regulators are employed. 

To give an idea of one of these 
simple and ingenious devices, it is 
shown in Fig. 61 how this regulator 
is combined with a Korting steam 
exhauster : d is the exhauster, which 
receives steam from a valved tube, 
b, connected with a bell, I, with a 
water-seal. The gas from the tube a 
passes through the exhauster to the 
pipe g. If an excessive pressure 
develops in the main a, the gas, by 
means of the tube m, raises the bell 

FIG. 61. I, which in its turn effects a wider 

opening of the steam-valve and so 

increases the exhaustion. If the pressure exceeds a certain limiting value, a spring valve 
or partition in n opens automatically, and the gas discharges also by n into the pipe g. 

GASOMETERS. These are formed of large sheet-iron bells fitting one in the other 
and forming a perfect water-seal when they are inverted in a brick and cement reservoir 
of water. To economise water, the reservoir is partially filled up by a brickwork cone 
(termed the " dumpling "), starting from the periphery at the base and rising towards 
the centre, as shown in Fig. 62 ; the gas exit and entry pipes project a little above the 
surface of the liquid. At a certain point (not shown in the figure) these two pipes can 
be put into direct communication, so that, in case of accident to the gasometer, the gas 
can still be led to the mains without interrupting the work. 

To economise in the number and size of the reservoirs and to have gasometers of 
considerable capacity, so-called telescopic gas-holders are now used. These consist of 
several concentric bells (five or six), of which only the smallest is covered, whilst the others 
are caught up peripherally during the rising (or filling with gas), forming a water-seal all 
round, as shown in Fig. 63. In order that the bells may rise centrally they are furnished 
outside with pulleys running along vertical iron guides. The pressure of gas in the gaso- 
meter can be calculated from the weight of the bell outside the water, together with the 
surface and diameter of the bell itself. 

The pressure in the gasometer or mains can be registered automatically by placing 
them in communication with an automatic pressure-measure like that shown in Fig. 64. 
In this the gas raises or lowers a bell fitted with an index which registers the different 
pressures during the day on a paper wound round a cylinder rotated once in 24 hours 
by clockwork. 

There are other forms of pressure indicators, but the above, although old (in principle), 
is still largely used, being simple and exact. 





GASOMETERS, PRESSURE REGULATORS 49 

In order to avoid the serious consequences contingent on a gasometer reservoir cracking 
or leaking, iron reservoirs built above ground are preferred to-day, the slightest escape 
being then observable and remediable at any moment. Such a suspended telescopic 
gasometer is shown in Fig. 63. 

To meet the enormous daily consumption of gas in large cities more and more capacious 
gas-holders are required sufficient to contain 3 or 4 days' supply and so avoid the incon- 

veniences of an interruption of work 
(from damage, stoppages, &c.). In 
Milan, before 1908, the largest of the 
gasometers (measuring altogether 150,000 
cu. metres) had a capacity of 26,000 cu. 
metres ; after 1908, at the Bovisa (Milan) 
wo*ks a new one was brought into use 
which holds 80,000 cu. metres and cost 
little less than 40,000. The firm of 
Krupps constructed for their own works 
a gasometer holding 37,000 cu. metres ; 
the largest at Berlin contains 80,000 cu. 
metres ; that of Chicago 120,000 cu. 
metres ; and the last built at New York 
has a cement reservoir and a capacity 
of 500,000 cu. metres ; in London in 
1888 one was built holding 230,000 cu. 
FIG. 62. metres, and in 1892 another with six bells, 

containing 345,000 cu. metres and having 

a diameter at the base of 95 metres. Naturally these gas-holders represent large amounts 
of capital, the cost even for capacities of 30,000-40,000 cu. metres being tens of thousands 
of pounds. Fig. 65 shows diagrammatically the arrangement of a gasworks in the middle of 
the nineteenth century. 

PRESSURE REGULATORS FOR CONSUMERS. In order that consumers may 
have a uniform pressure in their 
pipes and obtain regular, non- 
oscillating flames with a normal 
consumption of gas, it is necessary 
to use pressure regulators where the 
principal mains .leave the works, 
these regulating the pressure auto- 
matically even when the consump- 
tion is at its maximum or minimum. 
Since gas is lighter than air, the 
pressure is regulated more easily 
and the flow facilitated by con- 
structing the works at the lowest 
point of the town. In the gas-holder 
the pressure is usually 15 cm. of 
water, whilst in the mains it is 
about 2 cm. 

A regulator as ingenious as it 



is simple was devised by Clegg 
and is in general use at the present 
time (Fig. 66). In a metal cylinder, a, filled with water, a bell, b, can be raised or 
lowered according as the gas supplied at / has a greater or less pressure. The pressure 
in the bell can be varied by altering the size of the aperture in tube / by which the gas 
is admitted. The orifice i at the upper end of / can, indeed, be closed to a greater 
or less extent by a metal cone, e, attached by a chain to the bell, with which it rises if the 
pressure is excessive thus diminishing i and hence the pressure in the bell or falls if the 
pressure diminishes too much, more gas then entering through i and the normal pressure 
being thus re-established. This normal pressure can be fixed according to the needs of 
any particular time, by placing on the bell weights, d, calculated tp give the required 




FIG. 03. 



50 



ORGANIC CHEMISTRY 



pressure. By means of this simple regulator the gas issues from h at a constant pressure 
and can be immediately passed into the mains. 

In general, however, the pressure is not the same in all the mains, but diminishes as 
the distance from the works increases. But it is not advisable to have the pressure too 
high, since the losses due to unavoidable leaks in the pipes are greater the higher the 
pressure, and the latter is usually maintained at 15-20 mm. of water at the points most 
remote from the works. 

In order to render the distribution of the gas to considerable distances more economical, 
attempts have been made to employ a pressure of 1-1-5 atmos. on the gas, the latter 
being preferably from vertical retorts and as free as possible from naphthalene. 

GAS-METERS. These are used to measure the gas in factories and private houses, 
since nowadays payment is according to the volume con- 
sumed and not according to the number of burners, as was 
once the custom. Dry meters have disappeared almost 
everywhere, general use being made of the water meters 
devised by Clegg and by Malam, and since improved so 
that they are now perfect gas-measurers. The principle 
on which their working is based is shown clearly by Fig. 67, 
representing an old form of the Malam meter. A cylindrical 
chest, X, half -filled with water, contains a drum rotatable 
about a horizontal axis and divided into four chambers, 
A, B, C, and D, communicating at the centre by means of 
the narrow slits b, and opening into the periphery at X by 
the slits c. The gas is led by the tube a into the central 
part of the drum and, in the position shown in the figure, 
communicates only with the slit b of the chamber D ; 
the latter is thus slowly filled with gas (which has a 
slight pressure), the drum being thereby raised and water 
caused to escape from c. Thus the chamber D becomes 
filled with gas in the position occupied by C, which has 
allowed its gas to escape gradually, the rotation indicated 
by the arrow having caused it to fill with water through 
the corresponding slit, b. Subsequently the gas fills the next 
chamber, A, which displaces Z), and so on. The gas passing 
through this apparatus proceeds along the tube K to the 
consumer's burners. If all the taps are turned off, the 
drum cannot allow the gas to escape from it, and hence 
does not turn. The chambers have definite volumes, and 
if the axis of the drum is connected with a suitable mag- 
nifying apparatus the number of turns of the drum and 
consequently the volume of gas traversing it can be 
measured. 

This apparatus exhibits many structural defects which 
cause inaccurate measurements, and are now avoided by 

the meter shown in Figs. 69, 70, and 71. Here the drum has transverse walls which 
are inclined and not parallel to the axis (Fig. 68, V, W), so that the filling with 
the gas or water and the discharge take place gradually and do not cause oscillation 
of the flame. The gas enters by the tube I into the division k (Figs. 69 and 70) and 
passes into E through the orifice i, regulated by a floating valve, h. Thence the gas 
goes to the anti-chamber, B, by way of the elbow-tube, nx, opening above the level, 
W, of the water. The aperture, o, connecting the tube, x, with the anti-chamber is large 
enough to admit of the passage of the axis of the drum, but remains closed owing to the 
level of the water being above it. As the slits of the drum gradually present themselves, 
the gas enters successively the chamber of the drum from one side and issues at the other 
into the outer casing, A, then passing through the tube g to the gaspipes. Water (or better, 
a mixture of water and glycerine, which does not freeze) is introduced by the opening V, 
the level of the liquid being fixed by the tube n, so that the flow of gas through the valve i, 
is regulated ; the excess of water is discharged by the tube n and passes into the reservoir, m, 
thence by the tube-J to S, the orifice, u, of which is left open while the water is being added, 




FIG. 64. 



GAS-METERS 



51 



The axis of the rotating drum has, at one end, a continuous screw, a (Fig. 71 ), which moves 
a toothed wheel, a ; the latter, by means of the axle, e, produces rotation of a clockwork 
arrangement in F, so constructed that one wheel indicates litres and tens of litres, another 
cubic metres, a third tens of cubic metres, and a fourth hundreds of cubic metres. 




FIG. 65. 

C = horizontal retorts ; B = hydraulic main for separating the tar ; D = tubes for cooling 
gas ; O = washing towers (scrubbers) ; M = chambers containing Laming mixture for purifying ; 
O = single-lift gasholder ; S&i = entry and exit gaspipes. 





FIG. 66. 



FIG. 67. 



FIG. 68. 



The last few years have seen the successful introduction of the new dry meters and of 
automatic meters, of which alone Berlin contained 84,000 in 1905. By placing a 10-pfennig 
piece into one of these automatic meters, 500 litres of gas are supplied. In 1906 Berlin 
had in addition 191,000 ordinary meters. 

YIELD, VALUE, AND PRICE OF GAS. These vary with the nature of the coal used 
and with the conditions of carbonisation. In the large gasworks of the principal European 



52 



ORGANIC CHEMISTRY 



towns the yields usually vary between the following limits : coke, 63-76 per cent., more 
commonly 69-71 per cent. ; tar, 4-6 per cent. ; ammonia liquors, 9-8-12-5 per cent. ; 
gas, 25-31 cu. metres (of sp. gr. 0-360-0-480). At Berlin every ton of coal yielded on 
the average 287-3 cu. metres in 1900, 305 in 1901, 320 in 1902, and 324-4 in 1904, in addition 
to 690 kilos of coke, 54 kilos of tar, and 120 kilos of ammonia liquors. 

In many gasworks at the present day, instead of installing new plant, increased con- 
sumption of gas is met by mixing with water-gas (or blue gas), and as the calorific value of 
this is only about one-half that of coal-gas, benzene or heavy petroleum vapours are also 
added. Water-gas generators give a rapid production, do not form naphthalene or tar, 
and yield a gas costing less than half that of ordinary gas ; this is, however, very rich in 
carbon monoxide, which has caused numerous cases of poisoning in the United States, so 
that the medical men are now (1910) instituting a campaign to forbid the use of water- 
gas. 1 

The cost of manufacture of bituminous coal-gas varies with the different factors 
affecting its production, especially with the size of the works, the prices of coal and labour 
and the greater or less completeness with which the secondary products (ammonia, 





FIG. 69. 



FIG. 70. 



cyanides, sulphur, tar, &c.) are utilised. In Berlin the mean cost of manufacture seems 
to be less than 0-75^. per cubic metre, while at Milan it is about 0-85d. 2 Gas varies in 
price in different towns from 1-15 to 3-8d. per cubic metre (32-100d. per 1000 cu. ft.) ; in 
Paris it is 1-9, in Milan 1-25, in Oneglia 2-9, in Messina 3-2, in Venice 3-5, in Catania 3-8, 
and in Naples 3-ld. per cubic metre. [In England often much cheaper. Translator.'] 

STATISTICS. The consumption of lighting gas (subject to tax) in Italy in 1902 was 
139 million cu. metres, and exempt from taxation (for engines, &c.) 56 million cu. metres. 
In 1898 the total production was 198 million cu. metres ; in 1902, 211 million cu. metres ; 
in 1908, 308 million cu. metres obtained from 1 million tons of coal, with a yield of 51,000 

1 Water-gas, reinforced with benzene and mineral oils, costs about 15 per cent, more than ordinary gas but 
presents various advantages : without expensive plant, a production higher than the capacity of the works 
can be supplied ; part of the coke is utilised, over-production and consequent lowering of the price being thus 
avoided ; less consumption of coal for gas and hence less danger of rise in price of coal ; less labour ; rapid pro- 
duction even in the event of a strike. In England over 500,000,000 cu. metres are produced per annum. 4 grins, 
of benzene per cubic metre of gas increase the luminosity by one candle. A mixture of two-thirds of illuminating 
gas and one-third of water-gas gives a luminosity of sixteen candles when treated with about 40 grms. of benzene, 
the cost of the latter beins about 0-6d. per cubic metre. 

* We give here an approximate industrial balance-sheet referred to one ton of coal and to the conditions employed 
in the Milan gasworks : 

(a) Receipts : 264 cu. metres of gas (290 actually produced, less 9 per cent, for escapes and consumption in 
works) at 0-13 lira gives 34-32 lire ; 700 kilos of coke, 22-40 lire ; 45 kilos of tar, 1-35 lira ; 9 kilos of ammonium 
sulphate, 2-70 lire ; cyanides, graphite, slag, ashes, 0-06 lira. Total receipts, 60-83 lire. 

(6) Expenditure : 1 ton of coal, 30 lire ; coke for heating the furnaces (160 kilos), 5-12 lire ; purifying and 
Laming mixtures, 0-37 lira ; sulphuric acid and expenses for ammonium sulphate, 1-44 lira ; salaries and wages, 
10-58 lire; taxes, 0-67 lira ; fire insurance, 0-091 lira ; workmen's insurance, 0-175 lira ; general expenses, 1-10 lira ; 
maintenance of works, private and public expenses, new plant, 3 lire ; maintenance of meters and sundry other 
expenses, 0-090 lira Total expenditure, 53-23 lire. 

Net profit, about 7-60 lire. 




GAS STATISTICS: TESTING 53 

tons of tar and 709,000 tons of coke ; in 1909 the gas produced in Italy in 198 works 
amounted to 318 million cu. metres having a value of two millions sterling. At Milan 
in 1903, 40 million cu. metres of gas were produced, in 1905 about 47 million cu. metres, 
in 1907 almost 58 million cu. metres, and in 1908 about 61 million cu. metres (7000 
incandescent gas lamps being used for public lighting). Paris alone consumes annually 
350 million cu. metres, two-thirds by night and one-third by day (for engines, &c.), and 
Berlin in 1908 about 250 million cu. metres (in this city gas manufacture is municipalised, 
and the community draws an annual profit of about 350,000). From 1886 to 1904, the 
consumption in Brussels increased from 15 to 39 million cu. metres, that is, from 85 to 
204 cu. metres per head per annum. 

The various sources of light used to supply the needs of Paris in 1889 were in the 
following proportions : wax, tallow, stearin, 1-6 per cent. ; vegetable oils, 4-5 per cent. ; 
petroleum, 17-7 per cent. ; electricity, 18-9 per cent. ; gas, 57-3 per cent. In Berlin, 
where the consumption of gas in 1889 was 117 million cu. metres and where 54,000 tons 
of petroleum were used for lighting purposes, the proportions were as follows : petroleum, 
50 per cent. ; gas, 47 per cent.; electricity, 3 per cent. 

England carbonises annually 1 6 million tons of coal 
(in 1906) to procure 4500 million cu. metres of illumi- 
nating gas. Germany, in 1896, distilled 2,727,000 tons 
and consumed also one million tons of petroleum, 
equivalent to 2000 million cu. metres of gas ; in 1905, 
310 large gasworks used 4,500,000 tons of coal, of 
which one-fourth was imported from England, and 
700 other small works carbonised a total of 1,000,000 
tons ; in 1910, the total coal used for gas in Germany 
amounted to about 6,500,000 tons, 1 one-half the total 
production being used for gas-engines, of which there 
were 35,000 developing 170,000 horse-power (in 1898 
there were about 22,000 gas-engines using 33 per cent, 
of the total gas produced). 

In the United States 1640 million cu. metres of lighting gas were produced in 1907, 
the value being 3,200,000. In 1909 the United States contained 1296 gasworks with a 
capital of 183,107,400, the number of officials being 13,515 and the number of operatives 
37,215. The output of gas and other products was valued at 33,400,000, and 53 per 
cent, of the total production consisted of water-gas. In Japan the industry was Started 
only in 1901, and in 1907 the production had reached 44 million cu. metres. 

The manufacture and nature of air gas, producer gas, suction gas, Riche gas, water gas, 
&c., are described in vol. i (p. 393). 

PHYSICAL AND CHEMICAL TESTING OF ILLUMINATING GAS. As regards 
the determination of CO, CO 2 , N, and O, Orsat's apparatus (see vol. i, p. 375) gives good 
results. The estimation of hydrogen is effected with the ordinary Hempel burette or 
simply by determining the diminution in volume of the gas after passing it through a 
capillary tube containing palladinised asbestos heated at about 100 (see vol. i, p. 137). 
Then comes the determination of unsaturated and aromatic hydrocarbons, which are all 
absorbed by fuming concentrated sulphuric acid, the gas being measured before and 
after the absorption in the Hempel burette (the gas being washed with potash after the 
absorption). The methane is estimated by exploding the gas remaining in the burette 
with a known volume (in excess) of oxygen by means of an electric spark, 2 vols. of the 
gaseous mixture (gas + oxygen) disappearing for every 1 vol. of methane, according to 
the equation : 

CH 4 + 2O 2 = C0 2 + 2H 2 0. 
1 vol. 2 vols. 1 vol. condenses 

1 For the production of gas in Berlin 352,000 tons of German coal and 397,000 tons of English coal were used ; 
at the English ports the coal cost 8s. l%d. per ton in 1904 and 11s. 4Jd. in 1909. The cost of transport from the 
English mines to Berlin amounted to 7*. 3id. per ton, whilst from the German mines at Ruhr to Berlin it exceeded 
8s. lid. At the gasworks in Berlin the English coal cost 16a. 3d. per ton, and the German (from Silesia) 20*. 4d. 
per ton. In Germany 44 million cu. metres of gas were consumed in 1859, 350 million cu. metres in 1879, about 
500 million cu. metres in 1889, almost 1200 million cu. metres in 1899, and about 1800 million cu. metres in 
1908, there being 1200 factories, representing a capital of 80,000,000 (for Berlin alone 12,000,000 and for Munich 
640,000). In 1880 only one-half of the gasworks were municipalised, and in 1909 two-thirds, the profit amounting 
t<> 8 to 13 per cent, on the capital. 



54 



ORGANIC CHEMISTRY 




To estimate the ammonia in the purified gas, 200 litres of it are passed through 10 c.c. 
of an N/10 solution of hydrochloric acid, the excess of which is subsequently determined 
by titration. 

The determination of the total sulphur compounds can be simply effected, according 
to F. Fischer, as follows : About 50 litres of the gas (measured by a good meter) are 

burned in a small Bunsen burner, g (Fig. 72), 
in the drawn-out bulb, A, of a bulb-con- 
denser arranged as shown. All the sulphur 
of the sulphur compounds burns, forming 
sulphurous and sulphuric acids with the 
water from the combustion of the gas, this 
condensing in the bulbs of the condenser 
and being collected at the bottom in a 
beaker by means of the tube e. The com- 
bustion is regulated so that gas containing 
4-6 per cent, of oxygen escapes at o. Water 
FIG. 72. enters the condenser at z and leaves at n. 

At the end of the operation, the bulbs are 

rinsed out with water and the sulphurous acid in the liquid oxidised by means of pure, 
neutral hydrogen peroxide solution ; the. sulphuric acid is then titrated with N/10 sodium 
hydroxide solution. If the sulphuric acid is estimated gravimetrically with barium 
chloride, the oxidation of the sulphurous acid must be effected with hydrogen peroxide 
free from sulphates. The quantity of sulphuric acid found 
gives the total sulphur-content of the gas. A well -purified gas f 
contains less than 0-5 grin, of sulphur per cubic metre. 

The hydrogen sulphide is estimated separately by passing a 
known volume of the gas through ammoniacal silver nitrate 
solution, which is afterwards acidified with a little nitric acid, 
the silver sulphide being filtered off, washed, dried at 100, and 
weighed. 

The calorific power can be determined fairly rapidly by 
means of the Junker calorimeter (Fig. 73, section, and Fig. 74), 
which consists of a metal cylinder, C (the letters refer in all 
cases to Fig. 74), which is mounted on three feet, and inside 
which a known volume of the gas is burned by means of the 
Bunsen burner, n. The hot products of combustion pass several 
times up and down the calorimeter and issue at the outlet S, 
which is furnished with a valve and also regulates the air- 
draught. Passing in a direction opposite to that of the gases 
of combustion and in alternate adjacent chambers is a current 
of water which enters by w the small reservoir m, the excess 
being carried off by the overflow, 6, while a regular stream 
passes through the tap e (furnished with an indicator) into the 
calorimeter at a temperature given by the thermometer x, and 
flows away at c at a higher temperature, shown by the ther- 
mometer y. When the combustion is started, the entry of 
water is regulated by means of e, so that the thermometers, 
x and y, indicate a temperature difference of 10-20 ; when 
the flow of both gas and water is constant, the thermometer y 
soon shows a constant temperature. 

The gas is measured by the meter, G, and then passes 

through the regulator, P, to the Bunsen burner, n, which is drawn from the calorimeter to 
be lighted and is then pushed in again to the height q (about 6 in. up). If the apparatus 
is in order, no water should fall from d into the cylinder, v. 

When water is discharging from b and from c, and the thermometer remains stationary, 
as soon as the index of the meter reaches the zero mark or a definite number of litres, 
the rubber tube c is instantly placed from t into V, which is a graduated cylinder placed 
quite close to the discharge-funnel, t. In the cylinder V is collected all the water which 
is discharged during the combustion of a definite volume of gas (in the proportion of 




FIG. 73. 



CALORIFIC POWER OF GAS 



55 



100 to 200 litres of illuminating gas or 400 to 800 litres of suction gas or Dowson gas per hour). 
Exactly at the moment when the meter indicates the volume of gas fixed upon, the rubber 
tube, c, is removed from V to t. During the course of the experiment the small variations 
in the indications of the thermometer y are noted at intervals, the mean temperature 
being subsequently determined. 

The graduated cylinder, v, contains the condensed water (a c.c.) formed during the 
combustion of the gas, and this, in condensing, has given up to the water of the calori- 
meter a certain quantity of heat, which must be subtracted before calculating the net 
calorific power. The gross calorific power, U, expressed in calories per cubic metre, is 

A. T. 1000 
calculated by means of the formula : U = , where A indicates the quantity 

of water in litres collected in V, and Q 
the volume of gas burned. If, for 
example, Q = 3 litres, A = 0-900, T = 
18 (that is, 26-77, the mean of six 
readings of the thermometer y, less 
8-77 shown by the thermometer x to 
be the temperature of the water enter - 

0-900.18.1000 

ing at e), we have U = 

= 5400 Calories per cubic metre of 
gas. In cases where the gas is used in 
engines or other apparatus from which 
the products of combustion issue at a 
temperature above 65, the water-vapour 
does not condense and the gross calorific 
power must be diminished by. the heat 




FIG. 74. 



due to the condensation of the water -vapour produced by the combustion of the gas in 
the calorimeter. From U must hence be subtracted a value obtained by multiplying by 
60 the number of c.c. of water condensing during the combustion of 10 litres of gas. 
This net calorific power, U 1 , is, for illuminating gas, usually 10 per cent, lower than the 
gross calorific power, U. 

The specific gravity sometimes serves to test the constancy in composition of gas or 
to compare two different gases ; it also gives a rough idea of illuminating power, since 
the specific gravities of the more highly light-giving hydrocarbons acetylene (0-920), 
ethylene (0-976), propylene (1-490), and benzene (2-780) are higher than those of the 
non-luminous components hydrogen (0-0695), methane (0-559), &c. The specific gravity 
can be determined rapidly and exactly with the Bunsen effusiometer (see vol. i, p. 39). 

ILLUMINATING POWER. There is no absolute measure of the power of different 
sources of light, but these can be compared when a conventional unit has been chosen. 

This standard of light has been differently chosen in different countries and has been 



56 ORGANIC CHEMISTRY. 

continually modified. Thus in England spermaceti candles are used of such size that 
six weigh 1 lb., while, when burned, they lose 7-78 grms. (120 grains) per hour with a 
flame 45 mm. in height. In Germany in 1872 a paraffin candle 20 mm. in diameter 
was employed, the wick having 24 threads and weighing 0-668 grm. per metre and the 
flame being 50 mm. high ; six of these candles weighed 1 lb. Use is now made in Germany 
of the more rational Hefner-Alteneck lamp, fed with a liquid of constant composi- 
tion, namely, amyl acetate, the compact wick, 8 mm. in diameter, protruding 25 mm. 




FIG. 75. 



FIG. 76. 



from the metallic sheath holding it ; the flame is 40 mm. high. In France and Italy 
the Carcel lamp is used, this consuming 42 grms. of purified colza oil per hour and having 
a wick which is 23-5 mm. in diameter, is formed of 75 threads, and weighs 3-6 grms. 
per 10 cm. 

The relative values of these different units is as follows : 1 Carcel = 9-600 English 
candles (spermaceti) = 8-768 German candles (paraffin) = 10-526 Hefner-Alteneck flames. 

The luminous unit being 
fixed, different sources of light 
and their illuminating powers 
can be compared by means of 
photometers. Of these, the one 
most largely used is that of 
Bunsen, which is based on the 
principle that the intensity of 
light produced on a definite 
surface by a source of light is 
inversely proportional to the 
square of the distance. If the 
distance between the source of 
light and the surface illuminated 
is trebled, the intensity of the 
illumination is diminished to 
one-ninth of its previous value. 
The luminosities of two flames, 
/ and /!, which illuminate equally a given screen and are at the respective dis- 
tances, L and L l9 from it, are directly proportional to the squares of these distances : 
/ : /j L z : Lj 2 , and if I I is the unit of measurement, the intensity of the other source 

L 2 

of light will be : / = -=-' The Bunsen photometer (Fig. 75) consists of a horizontal iron 

L \ 

photometer bench 3 metres long and divided decimally (into half -centimetres or milli- 
metres) ; at one end is placed the comparison electric or candle lamp or the Carcel lamp, 
the consumption of oil in which is regulated by a small pump actuated by a clockwork 
mechanism, weighing on a balance the consumption in a given time (indicated by a bell) 
this corresponding with 42 grms. of oil per hour. A screen of paper can be moved 
backwards and forwards along the bench and normally to it, the middle of the screen 
being rendered translucent by means of a grease spot (spermaceti) ; at the other end 




FIG. 77. 



I L - G A S 57 

of the bench is placed the light to be examined. When the screen is equally illuminated 
on its two faces, the grease-spot is no longer perceptible. The intensities of the two 
sources of light are then proportional to the squares of their distances from the screen. 

The measurement is made in a dark room and, in order to render more evident the 
disappearance of the spot on the two surfaces, the screen is placed between two mirrors 
arranged at an angle (Fig. 76). An improvement on the Bunsen photometer has been 
made by Lummer and Brodhun, who substitute for the screen with the grease-spot a 
closed box, h (Fig. 77), in which are two opposite circular apertures, these illuminating the 
two faces of a white screen, /, by means of light from the standard lamp, and that to be 
tested placed at the two extreme ends of the photometer bench. By means of a system 
of prisms, A B, the two faces of the white screen reflect the light on to two concentric 
zones of the field of the eye-piece, r. When the two faces of the screen are equally illumi- 
nated, the two zones of the field also appear uniformly lighted . x 



OIL-GAS 

In cases where the installation of a plant for the carbonisation of coal would be 
inexpedient, owing to the small consumption of illuminating gas, it may be convenient 
to prepare oil-gas by dropping into a red-hot retort (see later, " Cracking " Process in 
the Petroleum Industry) fatty residues, tar oils, resins, and petroleum. This destruction 
by heat produces a gas which can be readily compressed without separation of liquid, 
and, enriched with 25 per cent, of acetylene, is used for the illumination of railway carriages. 
Oil-gas can also be prepared easily and abundantly by dropping oil into gasogens con- 
taining red-hot coke. 

As early as 1815 public lighting with oil-gas was attempted (Liverpool used it for some 
years), but it was only after 1860-1870 that this industry assumed importance. From 
100 kilos of lignite paraffin oil are obtained 60 cu. metres of gas, and with a consumption 
of 35 litres of the gas per hour, 7-5 normal candles (German) are obtained ; its illuminating 
power is four times as great as that of ordinary lighting gas. If a greater yield of the 
gas is obtained, it loses in illuminating power. The purification of oil -gas is carried out 
in practically the same way as that of coal-gas. Mineral oil for gas and for engines is 
produced in large quantities in Galicia, where it is sold for less than 19-5d. per cwt. (4 lire 
per quintal) ; Germany alone imported 30,000 tons of it in 1909. 

1 Comparison between Various Sources of Light. To produce the luminous intensity of a Hefner candle- 
hour (HK), the following quantities of lighting materials must be consumed : 

,-Stearine, first quality 

,, third ... 

- Paraffin 

Two parts of paraffin and one of 
\. stearine ..... 
'Carcel: colza oil .... 
<a I Petroleum, flat wick 

9 -' ,, round wick 

5 

I Spirit : incandescent 

^Petroleum with Auer mantle 

It is easy to calculate the cost from the prices of the various methods of lighting, these varying from town to 
town and from country to country. In 1896 Lttpke calculated the following numbers of normal candle-hours to 
be obtainable for one mark (one shilling), the calculation being only valid for that period and for Germany : wax, 
33 ; stearini!, 77 ; colza oil, 150 ; electric lamp with incandescent carbon filament, 150 ; fish-tail gas-jet, 625 ; 
acetylene and air with an edged burner, 716 ; oil-gas, 1660 ; water-gas with benzene, 1666 ; electric arc lamp, 
2232 ; Auer gas lamp, 2300 ; Auer water-gas lamp, 4350. 

From gas at l-9d. (0-2 lira) per cubic metre, as a source of heat. 1000 cals. are obtained for 0-38<Z. (0-04 lira), 
whilst, using electric current at 3-07<i. (0-32 lira) per kilowatt-hour, 1000 cals. would cost about 3-65d. (0-38 lira). 
For power purposes, the electric current [at 2-4d. (0-25 lira) per kilowatt-hour] costs more than double as much as 
gas [at l-73tf. (0-18 lira) per cubic metre]. 

During the past few years a considerable advance has been made by the use of incandescent electric lamps with 
metallic filaments (tantalum, tungsten, osmium, &c.), which reduce the consumption of electrical energy by one- 
half. But at the same time gas lamps have been improved by the use of high-pressure gas, and those with inverted 
flames are still decidedly more economical than metallic filament electric lamps. From the hygienic point of view 
the disadvantages of gas lighting have been exaggerated, as it has not been realised that the use of gas causes cir- 
culation and renewal of the air, and that the production of water-vapour and carbon dioxide are negligible compared 
with the similar effects produced by the respiration of human beings. 



7-87 grms. Acetylene .... 0-6 litres 


9-58 






Fish-tail . . 


19-0 




6-27 




<a 2 


Argand . . . . ' 


10 




6-93 
3-99 




| g A Auer .... 
Millenium (gas under pressure) 
^Auer with inverted flame. 


1-60 
0-75 
0-70 




2-76 




ft 


/ Arc lamp of small power . 


1-20 volt-amps. 


, 2-80 




| I Arc lamp of high power . 


0-25 


(3-60 




~ I Incandescent Edison 


3-70 


1-90 




'E | Metallic filament (osmium 




0-50 




g tantalum) . . 


1-90 




^Mercury vapour 


0-50 



58 ORGANIC CHEMISTRY 

PETROLEUM INDUSTRY 

Crude petroleum also goes under the name of mineral oil or naphtha, and 
is a more or less dark liquid (according to its origin) with a peculiar, pro- 
nounced odour. It is found in various parts of the earth in the strata of the 
tertiary epoch and also of preceding epochs. The principal centres of pro- 
duction are Baku (Russia) and the United States. 1 

In some places it overflows at the surface of the earth through porous 
rocks or clefts ; in others it is found accumulated under pressure in large 
cavities or pockets, since when it is reached by borings or wells, powerful jets 
rise above the surface of the earth often to the height of 100 metres, thus 
forming fountains of petroleum which last from a few weeks up to seven or 
eight months and throw up also large quantities of inflammable gases and 
sand. 

Some petroleum deposits have been gradually evaporated and oxidised 

1 History of the Petroleum Industry. The use of petroleum and of tar goes back to the earliest historical 
times (the Biblical legend relates that Noah rendered bis ark impermeable by means of tar, and in the construction 
of the Tower of Babel a mortar was used prepared with naphtha 1 (?) ). Certain races then employed naphtha 
as a combustible, and the Egyptians made use of it in the preparation of mummies. 

In small quantities petroleum is found in nearly all countries, but 95 per cent, of the total production is given 
by North America and Russia. Two centuries before petroleum was used in America that from Parma in the Apen- 
nines was used for lighting, e.g. at Genoa, Parma, &c. The most important petroleum wells now in Italy are in 
the Province of Piacenza (at Fioreniuola d'Arda) and at Salsomaggiore, Borgo S. Donnino, and Montechino ; 
less important deposits are found also in Calabria. At Velleia the industry has been worked for many years by 
a French company, many wells 200 to 450 metres deep having been sunk along the right bank of the Chero ; this 
company was absorbed by an Italian syndicate in 1907. 

In Austria the region richest in petroleum is Galicia. In 1895, when a well 300 metres deep was bored, a 
fountain was formed which, in thirty-six hours, yielded 5000 barrels of petroleum (1 barrel = 42 gallons = 
159 litres = 145 kilos). Still more important wells in other countries are mentioned on p. 66. 

In Russia the most important sources of petroleum are found in the province of 1-aku (99 per cent, of the whole 
production is obtained from an area of 6 sq. kiloms.), and partly at Grosny, to the north. From the most remote 
times, before Christ, sacred fires, fed by petroleum and by the inflammable gases liberated from it, have been kept 
burning uninterruptedly in the temples (down to 1880). During his voyage in the thirteenth century Marco Polo 
visited these marvellous springs of " oil not good to use with food but good to burn and also used to anoint camels that 
have the mange." 

In 1820 the Baku petroleum wells were declared the property of the Russian State, and the Government made 
concessions to contractors who worked them in a primitive manner until 1872. In 1873, the most important 
wells and petroleum-bearing lands were put up for auction by the Government, who levied a tax on the petioleum 
extracted. This condition of affairs was less favourable than that holding in the American industry, so that 
in 1877 the tax was repealed and the Russian petroleum industry, passing into the hands of great capitalists 
(Nobel, Rothschild, &c.), underwent extraordinary development and often competes advantageously with that 
of America. 

The first plant installed by Baron Thormann for the distillation of petroleum was constructed at Baku in 1858 
according to suggestions and plans furnished by Liebig, carried out by one of his assistants (Moldei.hauer), and 
improved by Eichler. The first wells bored on the American system date from 1869. Before 1870, the production 
was only 250,000 poods (1 pood = 16-38 kilo), but in 1872 it reached 1,500,000 poods and then grew with astounding 
rapidity (see later, Statistics). 

There are also important petroleum deposits in Japan, but the production is still limited : in 1874 it amounted 
to 126,150 kwan (1 kwan = 3-78 kiloo), in 1884 to 1,400,000 kwan, and in 1903 to about 126,000 tons. 

During recent times important sources of petroleum have also been discovered in Canada. 

The greatest impulse to the petroleum industry has come from the United States of America, where important 
deposits of petroleum have been found, first in the State of Pennsylvania (in a strip of land about 100 kiloms. 
long, the production of petroleum increased from 3180 hectolitres in 1859 to 16,000,000 hectolitus in 1874, the 
price per barrel falling during the same period from 100 lire or 4 to 6-5 lire or 5s. 2Jd. ; these deposits arc now 
apparently becoming exhausted), and then in Virginia, Ohio, Indiana, California, Louisiana, and 'J exas. At the 
present time the most important sources of petroleum in the United States are in the Washington district. 

The first studies on petroleum in America were made by Silliman in 1854, by fractional distillation, and these 
were folio wed by unsuccessful industrial efforts caused by the low production of the wells utilised and by many 
commercial difficulties, which were overcome by L. Drake in 1859 by the use of artesian wells. 

The first petroleum well in America was obtained by pure chance ; at Titusville in Pennsylvania a well was 
being sunk for drinking water and when a depth of 22 metres was reached, a continuous jet of petroleum 
appeared yielding 4000 litres of naphtha per day. 

Just as America was taken with the " gold-fever " after the discovery of gold in California, so the United 
States caught the petroleum fever. Pennsylvania was invaded by adventurers, and borings were made wherever 
the geological formation of the earth admitted of it; all had faith in the goddess Fortune, who, as always, 
favoured some and drove others to ruin and despair. In 1861 the number of derricks (used for boring) exceeded 
2000. The work was carried out hastily and without thought, usually empirically, the idea being to succeed fiist. 
Much petroleum was lost, and much was burnt, causing immense losses and ruin to numerous firms. 

Great capitalist companies were then formed and these studied x caliuly and rationally the technical and com- 
mercial problem and very soon created an enormous industry, which rapidly brought petroleum into common use 
all over the world. Ships and railways and then iron pipes ten and hundreds of kilometres in length served to 
transport the petroleum rapidly, continuously, and economically from the wells to the rcfiueiies and Irom these to 
the seaports, where it was shipped to the merchants. 



ORIGIN OF PETROLEUM 59 

during the lapse of ages, leaving a black deposit of mineral tar or asphalte (see 
section on Paraffin). 

ORIGIN OF PETROLEUM. Various hypotheses have been put forward to explain 
the origin of petroleum, and even to-day opinions are divided, probably owing to the 
fact that petroleum has not one single origin, since, in different parts of the earth's crust, 
it has different qualities and compositions. 

(1) Hypothesis of Inorganic Origin. A. v. Humboldt supposed petroleum to have 
originated from inorganic gaseous products under the influence of volcanic forces, and in 
1866 Berthelot advanced the hypothesis that, by the action of carbon dioxide on 
alkali metals inside the earth's crust, acetylides would be formed which with hydrogen 
would give acetylene derivatives, these then undergoing various condensations to form 
petroleum and tar. Byasson in 1871 explained the formation of the hydrocarbons of 
petroleum as due to the action of H 2 S, CO 2 , and water-vapour on layers of red-hot iron, 
this action being produced by the infiltration of sea-water, through clefts at the bottom 
of the ocean, in such a way that, together with calcareous matter, it was brought into 
contact with deposits of heated iron or iron sulphide. Mendelejeff (1877) regarded the 
hydrocarbons of petroleum as originating in the igneous strata of the earth's crust by 
the action of aqueous infiltrations on pre-existing deposits of carbide of iron or other 
metallic carbides. From 1877 to 1879 Cloe'z obtained support for Mendelejeffs hypo- 
thesis by showing experimentally that saturated hydrocarbons are formed when cast 
iron or spiegeleisen (substances which contain carbide of iron) is dissolved in acid. In 
1891 Boss brought forward again and modified Byasson 's hypothesis ; he assumed that 
volcanic gases, especially H 2 S and SO 2 , in contact with heated chalky rocks, would form 
gypsum, with separation of sulphur and production of saturated and unsaturated hydro- 
carbons (this would also give an explanation of the origin of sulphur, yet in Sicily, where 
sulphur abounds, no petroleum is found !). 

These various hypotheses on the inorganic origin of petroleum assume the formation 
of the latter in igneous primitive (archaic) geological strata, where the presence of organic 
compounds is excluded, the petroleum then finding its way to the higher layers of the earth's 
crust by seismic convulsions. But it is precisely these older archaic strata, deprived of 
water and of organic substances, which give no trace of petroleum. On the other hand, 
if the petroleum were formed in very hot strata, it should issue from the borings at a 
moderately high temperature, and there should have been separation of the light petroleum 
(more volatile) and the heavy into distinct layers. But this is not actually the case. 

However, during recent years this hypothesis has again come into favour, owing 
to the interesting work of Moissan (1894-1896) on the formation of saturated hydro- 
carbons by the action of water on aluminium carbide (see p. 34), and that of Sabatier 
and Senderens (1896-1902), who showed experimentally that, in presence of catalytic 
nickel (obtained by reduction of the oxide with hydrogen at 300), hydrogen and un- 
saturated hydrocarbons (ethylene, acetylene, &c.) give rise to saturated hydrocarbons 
such as occur in petroleum (p. 34). But even these syntheses do not yield very high 
and solid hydrocarbons like those present in crude petroleum, although recently (1908- 
1909) A. Brun, Stieger, and Becker showed that hydrocarbons similar to paraffin are 
formed by the interaction in the hot of iron carbide and ammonium chloride, even in 
absence of water. 

(2) Hypothesis of the Vegetable Origin of Petroleum. This was enunciated at intervals 
by Binney (by distillation of peat), by Kobell (by distillation of coal), and by Bischof, 
who considered petroleum to be formed by the action of sea-water on cellulose and 
on coal included in the geological strata of the earth's crust. This hypothesis of the 
vegetable origin was later supported or attacked by various writers, and to the fact 
that, in general, carboniferous strata do not contain petroleum, is opposed the discovery 
of small deposits of petroleum in the coal-seams near Wombridge and of certain 
petroliferous substances in Japanese coals ; but Hofer showed that, in the first case, 
the neighbourhood of bituminous schists, rich in the remains of fishes, could not be 
excluded, and, if it is desired to explain the formation of petroleum from marine 
vegetable organisms, it is not possible to conceive of a sufficient quantity of these to 
give rise to the immense amounts of petroleum now discovered. Further, other more 
recent geological investigations would exclude the vegetable origin of petroleum, although 
the most recent chemical work tends to render such origin highly probable. It is, indeed, 



60 ORGANIC CHEMISTRY 

found that petroleum rotates the plane of polarisation of light to the right (see later), 
as do most optically active vegetable substances, whilst substances of animal origin rotate 
it preferably to the left. Engler, however, states that this observation is not very con- 
clusive, since these active substances may be due to the condensation of unsaturated 
products originating in the decomposition of the prime materials (animals or possibly 
vegetables). Kramer and Potonie( 1906-1 907) point out that all petroleums (also certain 
lignites and ozokerite) contain algce wax, from which, _by various reactions and decom- 
positions, it is easy to pass to substances like petroleum, and simple substances, by poly- 
merisation (by heat and pressure), form more complex tarry substances, &c. ; the presence 
of wax demonstrates that petroleum is not formed in the hot by distillation, but rather 
in the cold and at high pressures. The prime material of petroleum would hence probably 
be the enormous formation of algce which have been produced at all epochs and are to -day 
accumulating in marshy places. These, during thousands of centuries and under the 
action of pressure and heat, could undergo the same transformations and putrefactions 
(mixed sometimes with animal remains), leaving the wax for the formation of petroleum ; 
so that petroleum would be formed in all epochs and is perhaps being formed now ! The 
varying composition of petroleum would be due, according to Kramer, to filtration through 
various geological strata, which would have removed greater or less quantities of bitu- 
minous products so as to produce pale, light petroleums like those of Velleia and Montechino. 
Hence the greater or less content of tarry substances cannot serve as an indication of the 
epoch of formation of a petroleum, since part of these substances may have been lost during 
the geological nitrations. 

(3) Hypothesis of the Animal Origin of Petroleum. This was enunciated and vigorously 
upheld by Hofer, and supported and supplemented by Ochsenius (1892), Zaloziecki (1892) 
Veith, Dieckhoff (1893), Aisinmann (1894), Heusler (1896), Holde (1897), Aschan (1902), 
and Zuber (1897, who supported only the organic origin), and more especially and most 
exhaustively by Engler (1888-1901). 

This hypothesis supposes that great layers of various fishes and molluscs, formed on 
the ocean-bed during past geological epochs, gradually underwent decomposition, first 
losing the nitrogenous components (albuminoids) as gaseous or soluble compounds, the 
remaining fats being slowly transformed partially into bituminous substances. These, 
together with the residual fats, under the action of great pressure and heat (developed, 
in part, by these decompositions) would yield glycerol, which would generate acrolein 
and then aromatic hydrocarbons, while the remaining fatty acids (by the action of hydro- 
gen formed in all these decompositions) would give rise to the various saturated hydro- 
carbons constituting petroleum, C0 2 being liberated. 

The animal origin hypothesis is also supported by the observation made by Fraas, 
that petroleum issues from the coralliferous banks of the Red Sea, and by the odour of 
petroleum exhibited by certain phosphorites which are undoubtedly of animal origin. 

The objection has been raised that, if petroleum were of animal origin, it should contain 
nitrogenous compounds. Although this is not necessary, yet the presence of nitrogen 
products (ammonia and pyridine bases, free nitrogen and ammonium carbonate) has 
been shown in petroleum and in gases emanating from the earth. Texas petroleum 
contains up to 1 per cent, of nitrogen. 

Engler showed experimentally that, under certain conditions, animal fats can be 
transformed into defines or analogous products in the laboratory (by distilling fish-oil 
under 4-10 atrnos. pressure). In 1909, Engler, Routala, Aschan, and others effected the 
laboratory production of naphthenes, paraffins, and heavy mineral oils, by heating amylene 
and hexylene under pressure and in presence or absence of aluminium chloride as catalyst. 

Many facts support the view that the petroleum of the geological strata studied has 
been formed at a low temperature and by slow but continuous reactions lasting for 
thousands of years. 

To the doubt that may be raised as to the enormous quantity of animal remains 
necessary to explain the large amounts of petroleum being raised at the present time, it 
may be answered that if the annual catch of herrings on the coasts of the northern seas 
and that of sardines by French fishermen were to accumulate on the ocean-bed for 2000 
years, it would be quite sufficient to explain the petroleum production of Russia. 1 

1 In 1903 the fish caught by 103,000 fishermen along the 6000 kiloms. of Italian coast weighed 62,000,000 kilos 
(15,000,000 in Sicily) and had a value of about 800,000 (in 1904, only 620,0(10). In the valleys of Comacchio 
during the month of October 1905, alone, were caught : 450,000 kilos of eels, 60,000 of mullet, 50,000 of various 



ORIGIN OF PETROLEUM 61 

It would, however, be^ necessary, for the preservation of this enormous cemetery of 
fish, that the corpses should not be eaten by other larger fish ; the conditions must then 
be such that fish approaching the cemetery are killed. And this is highly probable, as 
the existence of such conditions at the bottom of the Black Sea has recently been proved. 
In fact, below a certain depth, there is so much dissolved hydrogen sulphide that any 
animal is instantly poisoned there, its body going to swell the vast numbers that have 
preceded it at the bottom. 

With these proofs is connected the most recent and most rational interpretation of the 
origin of petroleum. It is supposed that the decomposition of the residual animal fats 
is aided by certain ferments as yet not studied anaerobic bacteria analogous to those 
which have been studied in the cases of the transformation of wood into coal, the fermenta- 
tion of cellulose, peat, &c. And the hydrogen sulphide formed at the bottom of the 
sea would be a product of the fermentations due to these bacteria. 

Rakusin (1905 and 1906) made a new contribution to the explanation of the origin 
of petroleum, by discovering in various petroleums a slight optical activity, undoubtedly 
due to substances of organic origin (animal or vegetable). Neuberg (1905-1907) has 
shown that, in the putrefaction of protein substances, pronounced quantities of optically 
active acids and amino -acids are formed, and by heating under pressure or dry-distilling a 
mixture of oleic acid with a little valeric acid, a product is obtained which, after purification, 
has the characters of naphtha as regards the optical rotation, boiling-point, and other 
properties. All this supports the organic probably animal origin of petroleum, and 
even if the fats do not give an optically active petroleum, the activity would be imparted 
by the decomposition products of the proteins. The optical activity of petroleum was 
recognised as far back as 1835 by Biot, who, however, drew no practical or theoretical 
conclusions from the observation. Rakusin observed that petroleums exhibit the Tyndall 
phenomenon (vol. i, p. 103) to a more or less marked extent, and since petroleums arc 
sometimes inactive and have varying chemical composition, he regards the different 
hypotheses concerning their origin as justified. Petroleum, as a liquid, must be considered 
as intermediate to natural inflammable gas and solid asphalte or ozokerite. Since the 
white cerasin which is extracted from ozokerite is dextro-rotatory, it must be concluded 
that ozokerite is of organic origin (the products formed by synthesis from simpler or 
artificial substances being optically inactive, see p. 22). 

The petroleum or similar substances prepared artificially from the elements possess all 
the properties of true petroleum, but are optically inactive. Hence the most certain 
criterion of the organic origin of a petroleum is its optical rotation. If a petroleum is 
optically inactive, it may have originated from a racemic product (optically and transitorily 
inactive, see p. 19) of organic origin, but may have been formed from inorganic materials. 
However, inactive petroleums are rare ; Rakusin (1907) has only found three such up 
to the present, one Russian (Surakhany) and two Italian (Montechino and Velleia), and 
he states that not only the degree of carbonisation of the petroleum (richness in carbon), 
but also its degree of racemisation must be taken account of in judging its geological age. 

small fish (acquadelle), whilst in October 1910, 985,000 kilos of eels and mullet were taken. Italy is, however, 
considerably behindhand in the fishing industry, owing to insufficient study of its seas and to the great technical 
deficiency of the methods employed by the fishermen, while the speculation of a few merchants makes fish in the 
great cities of Italy much dearer than in other countries. Consequently, Italy imports continually increasing 
quantities of fish of all kinds, the value of that imported during 1907 being over 3,000,000. In Germany in 1902, 
31,000,000 kilos of herrings worth 400,000 were caught, and in the ports of the Elbe and Weser fish of the 
additional value of 640,000 was taken. In the United States with 134,000 fishermen, fish of the value of 10,000,000 
was caught in 1903 ; and in 1909, 219,500 fishermen took 1,000,000 tons of fish of the value of 12,000,000, including 
100,000 tons of oysters worth 3,100,000, and 40,000 tonsof cod of the value 480,000. In France 95,500 fishermen 
caught fish worth about 4,700,000 in 1902, and in Norway 101,000 fishermen took 3,200,000 in 1905. In 
Holland 21,000 fishermen earned 900,000 ; in England 106,500 fishermen, 9,000,000 ; and in Spain, 121,400 
fishermen 1,800,000 

In the Caspian Sea during the winter of 1906, 129,000 seals were killed, the yield of oil being 2,245,000 kilos, 
and its value 25,000, without considering the fat and skins, each of which costs 8s. to 10s. On the coast of Tonquin 
30,000,000 kilos of fish were taken in 1893. 

To obtain an idea of the fertility of certain fish, the shad, a fish of the herring family, weighing up to 5 to 6 kilos, 
may be considered'; the female lays as many as 100,000 eggs, which can be fertilised artificially, as is done with the 
salmon and trout. " In North America the eggs are collected and despatched to the Central Pisciculture Station at 
Washington, where they are hatched in four days in Macdonald or Weiss tanks with flowing water at 18 to 19, 
and are immediately placed in the rivers, where they grow rapidly. Every year more than 100,000,000 eggs are 
fertilised in this way and from 1875 to 1890 the shad fishing showed an increase of 100 per cent., corresponding 
with 160,000. The female cod may lay as many as 6,000,000 eggs during its lifetime, and the turbot even 
9,000,000. In Italy there are only two schools of fishery, whilst in Germany there are thirty-four, in Franp 
seventeen, and in Japan one for each maritime province. 



62 ORGANIC CHEMISTRY 

In 1908, Zaloziecki and Klarfeld held that the optical activity of petroleum is due to 
the presence of terpenes or colophony ; but Neuberg regards it a.s due to decomposition 
products of amino-acids (valeric or isocaproic acid) formed from the proteins. Marcusson 
(1908) combats these last two hypotheses, and shows that it is more probable that the 
activity is derived from decomposition products (dextro-rotatory) of Isevo-rotatory 
cholesterols (and hence of animal origin, whilst the vegetable ones are dextro-rotatory 
and yield laevo -rotatory decomposition products). By distilling olein under pressure, 
Marcusson (1910) obtained hydrocarbons which had an optical activity equal to that of 
natural proteins and which he regarded as formed from the original cholesterols. By the 
action of ozone, Molinari and Fenaroli (1908) showed that the Russian and Roumanian 
petroleums examined by them contained no unaltered cholesterol, but this does not exclude 
the presence of active decomposition products, which, however, would not contain double 
linkings. In addition to dextro-rotatory compounds, Java and Borneo petroleums 
contain Isevo-rotatory substances which become dextro-rotatory at 350 (as happens when 
laevo -rotatory cholesterol is heated) ; also certain inactive fractions become dextro- 
rotatory when heated. Rakusin, Molinari, and Fenaroli showed that the optical activity 
increases in those portions of petroleum that have the highest boiling-point. 

COMPOSITION AND PROPERTIES OF CRUDE PETROLEUM. 

As obtained from the wells, crude petroleum varies in colour from yellowish 
to pale brown, or even black, according to its origin ; it exhibits a marked 
greenish fluorescence and a characteristic, garlic-like odour. The dissolved 
gas soon separates spontaneously, and sometimes, on oxidation in the air, 
petroleum deposits dark, bituminous substances (paraffin, tar). The lighter 
petroleums are the paler and have an agreeable, ethereal odour, whilst the 
heavier ones are darker and have an unpleasant odour. 

Certain petroleums have recently been found to be radioactive. 

The presence of sulphur in petroleum, even if much less than 1 per cent., 
injures its odour and colour. The specific gravity of petroleum varies from 
0-780 to 0-970. Petroleum obtained from Terra di Lavoro, Italy, has a high 
specific gravity (0-970) and certain Roumanian and Indian petroleums, rich 
in paraffins, show values higher even than this, sometimes as much as 1-3. 

Montechino petroleum has the sp. gr. 0-740 ; that of Velleia, 0-780 ; 
American, 0-800-0-870 ; Russian, 0-850-0-900 ; and Galician, 0-827-0-890. 

Different petroleums are composed, as a rough mean, of 13 per cent, of 
hydrogen and 87 per cent, of carbon, small proportions of oxygen, nitrogen, 
and sulphur compounds being also present. The hydrocarbons present in 
petroleum are numbered by the hundred, and they belong to different series, 
one or other of which preponderates according to the source. Thus, Penn- 
sylvanian petroleums are constituted almost exclusively of hydrocarbons of 
the saturated series C w H 2w+2 (derivatives of methane), which are also found 
in Galician petroleums, &c. 

Some petroleums contain as much as 40 per cent, of hydrocarbons solid 
at the ordinary temperature (paraffin), and these are left after distillation 
(e.g. Java petroleum) ; usually, however, much less than this is present, 
American petroleums having only 2-5-3 per cent., and those of Baku some- 
times only 0-25 per cent. Different petroleums can be distinguished by means 
of the ultra-microscope, the paraffin being dissolved in the colloidal condition. 

It is maintained by various chemists that the paraffin is not pre-existent 
in petroleum, but is formed during its distillation. This is contradicted by 
the fact that some petroleum pipes show deposits of paraffin, and this can 
also be separated from cold petroleum by special solvents. 

Hydrocarbons of the unsaturated ethylenv series, C n H 2n , preponderate in 
the petroleums of Burma and are abundant in those from California ; Penn- 
sylvanian petroleum contains about 3 per cent. Different petroleums can 
hence be distinguished by the quantities of bromine or iodine which they fix, 



COMPOSITION OF PETROLEUM 63 

by the amounts of hydrobromic or hydriodic acid then formed (Park and 
Worthing, 1910) or by the quantities of ozone they take up (Molinari and 
Fenaroli, 1908). 

Hydrocarbons of the same general formula, C n H 2n , but saturated (cyclic com- 

, CH 2 CH 2 

pounds, so-called naphthenes, or derivatives of cyclopentane, CH 2 \ | , 

X CH 2 CH 2 
,CH 2 CH 2 
or cydohexane, CH 2 \ j>CH 2 ) form 80 per cent, of Baku petroleums 

X CH 2 CH/ 

and occur abundantly in those of Galicia, together with about 10 per cent, 
of hydrocarbons of the aromatic series (recently (1910) hexahydrocumene has 
been identified). 

In a Russian petroleum and also in a Roumanian one, Molinari and Fenaroli 
(1908) found hydrocarbons derived from naphthenes with two double linkings 
and having the general formula C n H 2M _ 14 (for example, C 17 H 20 ). 

In certain petroleums small quantities of acetylene derivatives occur. 

It is found that petroleums produced in localities relatively near to one 
another often have different compositions ; according to David Day this is 
due to the fact that the unsaturated hydrocarbons diffuse less easily through 
sandy or other soils, and this system of natural filtration gives rise to various 
types of petroleum, with preponderance of saturated hydrocarbons in some 
and of unsaturated hydrocarbons in others. This explanation is more reason- 
able than that the separation has been effected by distillation. 

The products that distil below 180 are almost exclusively saturated and 
those distilling about 200 mostly unsaturated. 

The very small quantities of oxygenated substances contained in petroleum 
(often less than 1 per cent, and rarely 5 per cent.) are composed of phenols 
and organic acids (e.g. in Galician petroleum). 

The traces of nitrogenous substances found in various petroleums (see 
above) support the hypothesis of the organic origin of petroleum. 

Almost all petroleums contain sulphur, which is very difficult to remove 
and imparts an unpleasant odour and bad colour. 

Usually the proportion of sulphur is about 0-10-0-15 per cent., but the petroleum 
of Terra dl Lavoro contains as much as 1-3 per cent., while still more is found (up to 3 per 
cent.) in those of Texas, Ohio, Indiana, and Virginia, from which it has to be separated 
(see later). 

The nature of the sulphur compounds present has not yet been completely denned, 
but the presence of mercaptans, thio-ethers, thiophene, and its homblogues (methyl- 
and dimethyl-thiophene) has been detected. According to Heusler it is only necessary to 
heat a little of the petroleum with a granule of aluminium chloride to detect the presence 
of sulphur, hydrogen sulphide being then developed. 

Also by fractional distillation and partly by the specific gravity, the four princpal 
types of petroleum can be distinguished. The products distilling below 150 form the 
b?nzinis (see later), then up to 280 are obtained illuminating petroleums or solar oil (or 
kerosene), and after 300 remain products used for the extraction of paraffin and vaseline 
(American) or for the preparation of mineral lubricating oils (Russian) : 

Crude petroleum Specific gravity Benzine Solar oil Residue 

Pennsylvania . . 0-79-0-82 10-20% 55-75% 10-20% 

Ohio . . . 0-80-0-85 10-20% 30-40% 35-50% 

Caucasus . 
Roumania 
Galicia 
Piacenza . 
Alsace 



0-85-0-90 


0-2-5 % 


25-30 % 


60-65 % 


0-85 


3-10 o/ 


70-80 % 


10-15% 


0-82-0-90 


5-30 % 


35-40 % 


30-50 % 


0-74-0-79 


25-40 % 


55-65 % 


4-8 % 


0-912 


5% 


35-70 % 


55-60 % 



64 



ORGANIC CHEMISTRY 



In some of the islands of the Caspian Sea (Tscheleken) is found a petroleum resembling 
the American type, with a large proportion of paraffin (5-5 per cent.), and in Columbia 
(S. America) petroleums like those of Russia (Caucasus) occur. 

The Italian 'petroleums vary considerably in composition and those of Emilia and 
Piacenza are so pale and so rich in benzine and poor in residues that it is supposed that 
they are the condensed more volatile products of more important deposits not yet dis- 
covered. In the distillation of the Velleia petroleums at Fiorenzuola d'Arda the little 

residue obtained is added 
to the crude petroleum 
to be refined and thus 
becomes distributed in the 
lighting oil, so that the 
less remunerative residues 
are never placed on the 
market. The absence of 
optical activity in the 
petroleums of Montechino 
and Velleia (see above) 
seems to confirm the view 
that they are derived from 
more important deposits, 
in which optically active 
products would probably 
be found. 

EXTRACTION AND 
INDUSTRIAL TREAT- 
MENT OF PETROLEUM. 
From the most remote 
times petroleum has been 
raised in China by means 
of wells similar to the pre- 
sent artesian ones, which 
the Chinese used many 
centuries before Europeans 
for obtaining drinking 
water. In other regions 
in times gone by the 
petroleum flowing at the 
surfaces of the water- 
courses began to be sepa- 
rated and used ; then 
wide, shallow wells were 
dug and the petroleum 
raised to the surface in 
buckets. Nowadays, how- 
ever, petroleum is every- 
where obtained by wells 
bored into the earth like 
artesian wells, and some- 
times the petroleum flows up to the surface under great pressure, so that it forms 
a fountain (see Note, p. 65, and Fig. 78). It is supposed that the deposits of petroleum 
in the interior of the earth's crust are situated in large cavities or pockets, where there 
is often a lower layer of salt water (Fig. 79, W ) and on this floats a more and less abundant 
layer of petroleum, E ; and, in general, the upper part of the pocket is filled with inflam- 
mable gas, G, which exerts great pressure. If the boring, B, reaches one or the other 
layer, one or the other product is obtained in preponderance or even exclusively, and, 
after exhausting the aqueous layer, the same well may yield only petroleum. 

x The sinking of a well is begun with a boring 35-40 cm. in diameter by means of suitable 
boring tools worked by long rods and toothed gearing, or by compressed-air drills mounted 




BORING FOR PETROLEUM 



65 




FIG. 79. 



on wooden structures termed derricks (Fig. 80) ; the detritus of the bored rock is con- 
tinually carried away from the boring by a current of water, whilst in former times the 

much slower dry boring was preferably employed. When the petroleum layer is 

approached, the water of the well or tube begins to show drops of petroleum. The 

power is often supplied by portable steam-engines, which should not be placed too near 

the boring, since if the petroleum or gas escapes accidentally in any quantity during the 

boring, it may ignite and cause considerable damage by fire or explosion. 

In such cases it is hence advisable to transform the 
energy on the site, for instance, with electric motors. 
And even then fires and explosions have been caused 
by the accidental ignition of the gas mixed with air, by 
sparks formed by stones, issuing violently from the well 
along with sand and petroleum and striking the iron 
framework or the rails of the woodwork. 1 

When the petroleum is not exuded under pressure, it 
is often raised by means of pumps, but this is not 
possible where much sand (up to 30 per cent.) is also 
extracted and has to be allowed to deposit ; this is 
the case at Baku, where, however, one-third of the 

petroleum issues under pressure. 

During recent years there have remained relatively few " fountains " at Baku, and 

the petroleum of the sandy wells, which cannot be raised by pumps, is extracted by special 

" bailers " made of a cylinder of sheet- 
metal terminating in a cone and fitted 

in the lower portion with a valve which 

opens when the bailer (called a shalonka) 

becomes immersed in the petroleum and 

closes on raising by means of pulleys 

and windlass, the steel rope carrying 

the bailer being wound round a large 

drum a short distance from the well. 

The shalonka, containing some hecto- 
litres of petroleum, is discharged by 

inverting it over a channel. 

From the large reservoir near the 

wells, the petroleum passes by means 

of iron pipes to the refineries or to the 

despatching stations (suitable trains or 

vessels), which at Baku are very near, 

but in America some hundreds of 

kiloms. from the wells ; these pipes then 

traverse plains, mountains, and valleys, 

and in the same way and with the 

help of powerful pumping-stations, the 

refined petroleum is despatched to the 

place of loading. In 1905, the Standard 

Oil Company began the construction of 

another such pipe (pipe-line) to connect FIG. 80. 

the works at Kansas City with the coast ; 

the distance is about 1700 miles and the construction cost 880,000 and served to 

transport daily from 10,000 to 15,000 barrels of petroleum. 

1 Artesian wells for extracting petroleum have an average diameter of 25 to 50 cm., and vary in depth according 
to the region ; at Baku they were first of all 60 to 150 metres deep. But of recent years wells have usually been 
sunk to a depth of 250 to 350 metres (occasionally 1000 metres). In the Washington district of the United States 
the wells are from 700 to 850 metres, and near Pittsburg is the deepest of all, 1820 metres. The wells are 100 to 
200 metres apart according to the locality, and they remain active for five to ten years. 

The expense of boring varies with the district, that is, with the nature of the subsoil, and, under favourable 
conditions and for wells not too deep, each boring costs about 400. Those made in the Washington district 
cost even 1400 to 1600. At, Velleia in the province of Piacenza, the wells are little more than 100 metres deep, 
whilst at Salsomaggiore they have been bored to a depth of 400 metres, and in one case of 700 metres, in order to 
utilise for medical purposes the iodine-salt water whiphis obtained, together with alittle petroleum. Jn America the 

ii 5 




66 



ORGANIC CHEMISTRY 




Boiling-point 


Specific gravity 


40-70 . . 


0-635-0-660 


70-80 . . 


0-660-0-667 


80-100 . . 


0-667-0-707 


100-120 .. 


0-707-0-722 


120-150 .. 


0-722-0-737 



150-200 
200-250 
250-300 



above 300 



0-753-0-864 




FIG. 81. 



DISTILLATION. Crude petroleum cannot be used as it is for lighting, as it has 
a bad smell and colour, contains many impurities, and is composed partly of too volatile 
products, which might easily cause explosions or 
fires in the lamps. In order to avoid these dangers, 
the petroleum is subjected to exact refining, which 
is controlled by legal enactments and with special 
apparatus (see later). 

The refining is carried out in a manner which 
varies with the nature of the petroleum and usually 
consists of a fractional distillation and a chemical 
purification. The fractional distillation in the 
laboratory is carried out in Engler flasks (Fig. 81 ), 
which are of definite size and shape and permit 
of concordant results being obtained in all labo- 
ratories ; the following fractions are then weighed separately : 

I. Light or readily volatile petroleums : 

(a) Petroleum ether ..... 

(b) Gasolene ...... 

(c) Benzine , . . . 

(d) Ligroin (burnt in special lamps for lighting) 

(e) Petroline (used for de-fatting or cleaning) . 

II. Petroleum for lighting : 

I quality ....... 

II quality ...... 

III quality ....... 

III. Residues of the distillation : 

(a) Heavy oils : lubricating oils . . 

(b) Paraffin oil . . . . 

(c) Coke 

The industrial refining of petroleum consists in separating the crude petroleum into 
these three groups, I, II, and III. 

Apparatus is used for periodic or alternate distillation, or for continuous distillation. 

Periodic distillation is conveniently carried out in the so-called waggon-still largely used 
in America and at Baku. It holds as much as 2500 barrels at a time (Figs. 82 and 83). 

It is made of wrought iron 10-14 mm. in thickness, and has a corrugated bottom ; 
it is commonly 7 metres long, 4 metres wide, and 3 metres deep. The top is fitted with 
three flanged elbows which carry off the vapour. In thirty hours three distillations can 
be carried through, the residues being discharged through the three orifices, c. The 
heating is effected by means of these residues, which are forced into perforated pipes, r, 
in the double-arched hearth ; rational circulation of the products of combustion results in 
effective utilisation of the heat. 

More profitable use is made to-day of simpler, cylindrical boilers, which, although of 
larger dimensions, correspond almost exactly with the various types of steam-boilers, 
the heating being external, or lateral, or internal, or two of these together. Such boilers 

well is widened at its lowest jpoint,' where it| meets ,the] petroleum, by 'exploding a dynamite cartridge ("tor- 
pedoing ") 

A well sunk in 1891 at Balakhany, 270 metres deep, gave an uninterrupted jet producing 3276 tons of petroleum 
per twenty-four hours, and the mass of sand expelled covered the whole neighbourhood. A little distance away 
one of the Nobel Company's wells, in 1892, gave 13,000 tons per day. In February 1893 a well was sunk at 
Romany, near Baku, which for several weeks yielded 10,000 tons of petroleum per day ; the oil issued from the 
earth with such violence that the movement of the air broke the windows of neighbouring houses, and, as at first 
it was not possible to guide the jet into horizontal channels, all the iron plates used for this purpose being pierced, 
250,000 tons of petroleum were lost in five weeks In 1909 a new well at Baku gave, for a long time, 3500 tons of 
naphtha per day. A well bored at Maikop (70 kiloms. from the Black Sea), on September 12, 1910, to a depth of 
70 metres, gave a jet 64 metres above the surface of the ground and a production of 6000 tons in- twenty-four hours ; 
on September 18 the fountain caught fiie and five days passed bef6re it could be -extinguished. 

Fountains as rich as this are exceptional ; usually wells yield much less, and at Baku a well is generally abandoned 
when it gives less than four tons in twenty-four hours. In Italy, however, wells are used which give only a few 
hundredweights of petroleum per day ; some of the Italian wells produce only 60 litres a day, others as much as 
2500 litres or more 



0-7446-0-8588 
0-8588-0-9590 



DISTILLATION OF PETROLEUM 



67 



of 600-700 or more barrels capacity are commonly used even in America, where, however, 
both the more complex and more perfect Lugo apparatus and the Rossmassler apparatus, 
in which the heating is effected by superheated steam, are used. 

For the condensation of the vapours that distil over, complicated iron coils are arranged 
in cisterns through which cold water circulates continuously, the bore of the pipe being 
20-25 cm. at first and gradually diminishing to 5-8 cm. 

The distillate with specific gravity not exceeding 0-750 and b.pt. 150 forms the crude 
benzine and is collected and worked up separately. The distillate with sp. gr. 0-750-0-860 
forms the lighting oil, and the residue is treated separately. 




FIG. 82. 



FIG. 83. 



Continuous distillation is employed more especially at Baku, with large plants con- 
sisting of boilers arranged in series so that each boiler is maintained at a definite, constant 
temperature, the vapours passing from one boiler to the other only depositing in a con- 
densed form those portions corresponding with a given boiling-point and a given specific 
gravity. By feeding the first boiler which is at the highest temperature continuously, 
the others are also fed indirectly and kept full, each of them discharging a fraction of a 
definite, constant specific gravity. Naturally the higher temperature boilers are furnished 
with dephlegmators (Fig. 84), which cause ready deposition of the heavy oil carried over 
with the very hot vapours. In these boilers the heating or distillation is effected by 





FIG. 84. 



FIG. 85. 



means of superheated steam, which is usually obtained by passing steam from a boiler 
(D, Fig. 85) through a series of iron pipes heated in a furnace by direct-fire heat. 

In addition to other advantages, continuous distillation gives an increase of 30 per 
cent, in the amount of solar oil. The residue left after distilling the crude petroleum up 
to 280 bears the Tartar name of masut or the Russian one of astatki (ostatki). The amount 
of petroleum distilled in twenty-four hours corresponds with four times the capacity of all 
the boilers in the battery. 

The Nobel Company at Baku has boilers which distil 1000 tons of petroleum in twenty- 
four hours. During recent years rectifying columns similar to those used for alcohol 
have been employed, these admitting of a large production without the use of large 
boilers. 

In the " Black Town " near Baku, there are 200 refineries which treat the whole of the 



68 



petroleum of the district. The odour of petroleum is perceptible at a great distance, and 
the town is always covered and surrounded with dense, black smoke. The most important 
refinery is that of Nobel Brothers, which refines half of the annual output of the Caspian, 
although this firm possesses only one -eighth of the total number of wells. 

CHEMICAL PURIFICATION OF PETROLEUM. The petroleum distilling between 
150 and 300 is not yet suitable for lighting purposes, as it has a marked, rather un- 
pleasant odour ; it has a faint yellow colour, and contains substances which detract from 
its value. It was Eichler at Baku who first suggested purification by means of concen- 
trated sulphuric acid. 

This is carried out in large iron tanks with conical bases (Fig. 86), the petroleum being 
treated with several separate quantities (altogether 1-3 per cent.) of concentrated sulphuric 

acid of 66 Be. (nowadays the mono- 
hydrate obtained by the catalytic process), 
the mixture being vigorously agitated by 
compressed air blown in at the bottom of 
the tank, and each quantity of the acid 
separated after half an hour's rest. 

The sulphuric acid acts especially on 
the aromatic hydrocarbons (forming sul- 
phonic acids), the defines and the oxy- 
genated acid compounds, as well as on 
the colouring and sulphur substances. 
A small part (1-3 per cent.) of the petro- 
leum is resinified and the acid is turned 
black, but can still be used for the manu- 
facture of superphosphates. 1 In order to 
weaken the action of the acid somewhat, 
it is mixed with sodium sulphate ; further, 
in order that yellowing of the petroleum 
may be avoided, sulphuric acid contain- 
ing less than 0-01 per cent, of nitrous acid 
should be employed. After the action 
of the acid, the petroleum is washed 
thoroughly with water and then with 
1-1-5 per cent, of concentrated caustic 
soda solution (30-33 Be.), air being 
FIG. 86. passed in from beneath to effect mixing ; 

in this way the traces of acid remaining 

and also the phenolic compounds are removed. After the alkali has been separated, the 
oil is again well washed with water. The remaining petroleum is not clear, as it is 
emulsified with a little water, but it clarifies on standing and on being filtered rapidly 
through sawdust and salt, which remove all traces of emulsion. The alkaline petroleum 
residues are now used in some places to impregnate and preserve railway sleepers ; but 
sometimes they are subjected to dry distillation, which regenerates the soda and gives 
coke and unsaturated hydrocarbons and ketones (acetone, &c.). The heating of these 
alkaline residues also yields naphthenic acids (tridecanaphthenic acid), from which cheap 
antiseptic soaps are prepared. 

Some crude petroleums give a rather yellow solar oil, which is decolorised by exposure 
for some time to the sun in shallow tanks covered with sheets of glass. Sometimes the 
yellow tint is removed by dissolving in the petroleum traces of complementary blue or 
violet dyes ; as, however, nearly all commercial dyes are insoluble in petroleum, it is 
necessary to obtain from the manufacturers the bases of these colouring-matters, these 
being soluble. 

In certain cases, decolorisation is attained with infusorial earths, clays, or natural 
magnesium hydrosilicates. 

A most important operation for petroleum rick in sulphur (present especially as H 2 S) 

1 According to Ger. Pat. 221,615 of 1909 this black acid, containing sometimes as much as 2-5 per cent, of 
complex organic substances, may be purified by causing it to fall into pure, boiling sulphuric acid through which 
a current of air is passed ; all the acid distilling over is then pure and colourless. J. Fleischer (1907) obtains colour- 
less acid (45 to 50 B$.) by causing the black acid to diffuse through porous partitions washed by a little wate r . 




DESULPHURISING OF PETROLEUM 



69 



and hence dark and of unpleasant odour (like those from Canada, which can be used 
only as a combustible and not for lighting purposes) is that of a desulphurising according 
to the process proposed by Frasch (1888-1893) ; this consists in distilling the petroleum 
with an excess of a mixture of metallic oxides powdered copper oxide, 75 per cent. ; 
lead oxide, 10 per cent. ; iron oxide, 15 per cent. This operation reduces the sulphur- 
content from 0-75 per cent, or more to 0-02 
per cent. It is calculated that, by this 
method, about 50 tons of sulphur are 
extracted daily from Ohio petroleum, 
most of it being lost. 

The operation is carried out by simple 
mixing or by means of vapour. In the first 
case 6800 kilos (68 quintals) of the oxide 
mixture are added to 200 tons of petroleum 
in a large tank, the mixture being sub- 
jected to prolonged agitation by mechanical 
stirrers, which keep the oxidising mass at 
the bottom of the tank in continual motion. 

The petroleum is then decanted off into 
the fractional distilling apparatus, a second 
quantity of 200 tons of petroleum, together FIG. 87. 

with 4500 kilos (45 quintals) of oxides 

being added to the residue in the tank ; the operation is repeated four or five times 
before renewing the oxides completely. 

The Frasch process of desulphurising the vapour is far more rational and rapid ; it 
consists in passing the petroleum vapours from the distillation vessel (from 100 tons of 
petroleum) (A, Fig. 87) successively into two communicating cylinders, B and C, placed 
one over the other and enclosed by a metal casing, D, above the boiler. The vapours 
pass first into the casing, next into the lower cylinder, and then into the upper one, coming 
into intimate contact with the mixture of metallic oxides, which are kept moving and 
subdivided in both cylinders by means of rotating reels, h, provided with peripheral 
brushes, H. The oxidising mixtures in the two cylinders are renewed alternately, while 
the purified vapours, after traversing a gravel filter, G, which retains particles of the 
oxides carried over, are condensed in ordinary coils, F. By this process, some refineries 
are able to purify as much as 11,000 tons of petroleum per day. 





FIG. 88. 



FIG. 89. 



Recently petroleum has been desulphurised by means of metallic sodium, and treatment 
with aluminium chloride in the hot and under pressure is also recommended. V. Walker 
(U.S. Pat. 955,372, 1910) passes the vapours into columns fitted with perforated plates and 
containing anhydrous cupric chloride, the last traces of hydrogen sulphide being removed 
by passing the vapours into a solution of lead oxide in caustic soda. Robinson (1909) 
separates the sulphur by treating the petroleum with highly concentrated sulphuric acid. 

In well-refined petroleums, the proportion of sulphur is always less than 0-06 per 
cent., usually 0-02 per cent. 

PETROLEUM TANKS. The refined petroleum is preserved in large cylindrical 
sheet-metal tanks (Fig. 88), situated near the works ; they are whitened outside to reflect 



70 



ORGANIC CHEMISTRY 



the heat of the sun, and are furnished with charging and discharging pipes communicating 
with the pumping-station by which all the liquids in the works are circulated. 

For transport by land and sea, wooden casks holding 159 litres (about 145 kilos) were 
at one time exclusively used, but to-day land transport is effected by tank-cars (Fig. 89), 
which are now numbered in hundreds of thousands. For sea transport, tank-steamers 
are used (there are now 360 of these of the total capacity of 630,000 tons) (Fig. 90) ; when 
they arrive at their destinations in the ports of different countries, they are discharged 
by means of pumps into storage-tanks or directly into tank-cars. From these stores 
(there are tanks of 2000 tons capacity at Leghorn, Savona, Genoa, and Venice) it is 
dispatched inland in wooden or iron casks or in cans holding 14 kilos (17 litres) and packed 
in pairs in wooden cases. 





' FIG. 90. 
Carbone, coal ; j>etrolio, petroleum ; macchine e caldaie, engines ancfboilers. 



USES AND STATISTICS. The greater part of refined petroleum is still used for 
lighting purposes, either in the old lamps with flat wicks or in those with cylindrical 
wicks and flame -spreaders or in lamps with incandescent Auer mantles ; it can be used 
advantageously for household illumination in town and country. Part of it is employed 
for power purposes, as in internal -combustion engines it gives an efficiency of 25-37 per 
cent., whilst coal yields only 12 per cent. However, while in Russia large quantities of 
petroleum were used in the past in factories and for locomotives, nowadays it is being 
replaced by coal ; in America, on the other hand, the opposite is the case, and the Mexican 
Railway alone consumed more than 4000 barrels of petroleum per day for its locomotives 
in 1908. Its use on fast ships has the advantage of 28 per cent, saving in space. In 
America, about 19,000,000 barrels of petroleum were used altogether for railway loco- 
motives in 1907. Lastly, it is used as a disinfectant and for lubricating engines, &c. 

The production of petroleum has increased in a surprising manner, in spite of the 
growing development of the gas and electrical industries. The following figures illustrate 
this for the two great petroleum -producing regions : 



In 1874 
1884 
1894 
1903 
1905 
1908 
1910 



Caucasus (Russia) 
Tons 
100,000 

1,500,000 
5,000,000 
9,902,000 
7,969,239 
8,292,000 
9,500,000 



United States 

Tons 

1,500,000 

3,400,000 

7,000,000 

13,160,006 

17,636,000 

23,940,000 

26,000,000 



In America to-day petroleum is monopolised by huge " trusts," especially the Vacuum Oil Company and the 
Standard Oil Company of New Jersey, to which are affiliated seventy companies with a total capital of 18,000,000 
and employing 60,000 workmen and monopolising about 60 per cent, of American petroleum. The Standard 
Oil Company, founded in 1872, paid in dividends from 1882 to 1892 a total of 94,400,000, and from 1894 to 1903 
paid to its shareholders dividends of 33 to 48 per cent. 1 In 1906 President Roosevelt, under pressure of public 
opinion, waged war against this colossal [trust by rupturing the connection between the steel ring and the interests 
bound up with it and making them liable to a fine of over 6,000,000. In consequence of this commercial war of 
1906 the Standard Oil Company lost 25,000,000, of which 12,900,000 fell on Rockefeller, the well-known millionaire 
president of the company. The sentence was then annulled on appeal, but the result was that the company 
fought its competitors by lowering prices (petroleum that previously cost 30 centesimi (2-9d.) per litre has been 
lowered in price during the last few years to 15 centesimi (l-45rf.) ), and in 1908 made a net profit of 16,000,000, 
and proposed raising its capital to 100,000,000. This explains how Rockefeller has been able, without any great 
sacrifice, to make benefactions of so many millions during the past few years, especially for the extension of university 
study in America. The last sentence of the Supreme Court of Washington (May 15, 1911) gave judgment against 
the Standard Oil Company, for contravention of the law against trusts, and ordered dissolution of this powerful 
company within six months. 



PETROLEUM STATISTICS 



71 



One-third of the American production has been given by California, more than one- 
fourth by Texas, and one-sixth by Ohio, and now one-sixth is given by Illinois, one- 
fourth by California, and one-fourth by Oklahoma. In 1910 the Calif ornian production 
reached almost 10 million tons. 

The total production of the. world was about 12,000,000 tons in 1894, 31,000,000 in 
1905, and 38,000,000 in 1908. The following Table gives, in the first three columns the 
production in thousands of tons of each of the petroleum -producing countries of the 
world, and in the last three columns the percentages of the total amounts yielded by each 
country : 





1903 


1905 


1908 


Per cent, of the total production 


1900 


1902 


1908 


United States . 
Russia 
Dutch East Indies . 


13,600 
9,902 

870 


20,000 
7,969-2 
1,126-3 


23,940 
8,292 
1,143 


51-50 
42-41 
1-83 


52-51 
37-12 
3-50 


63-0 
21-8 
3-0 


Galicia 


728 


835-8 


1,754 


1-97 


2-90 


4-6 


Roumania 1 


381 


641-0 


1,148 


0-85 


1-74 


3-0 


British India . 


329 


599-8 


672 


0-87 


1-42 


1-7 


Japan 
Canada . 


126 


194-4 
91-9 


276 

70-5 


0-86 
0-18 


0-50 
0-24 


0-75 
0-20 


Germany 
Italy . . 
Peru 


58-9 
2-5 


81-3 
6-1 
5-4 


141-9 

7-08 
135 






0-35 
0-02 
0-35 


Various other countries 


79-0 













In 1890, Germany produced only 15,000 tons of crude petroleum. 

The country that consumes the most petroleum, after the United States and Russia, 
is Germany, where, in 1904, 970,600 tons were used for lighting, 143,000 tons for lubri- 
cating purposes, and 110,000 tons for various other uses ; in 1909, it imported about 
950,000 tons of refined petroleum and 31,400 tons of crude petroleum, of a total value of 
3,600,000. 

The importation into Italy has been as follows : 

1884 1890 1900 1904 1906 1907 1908 1909 1910 

Tons . 73,361 72,000 73,000 69,233 61,588 72,714 82,373 88,930 84,748 

and whilst in 1907 two-thirds of this came from the United States, one-fourth from 
Russia, and little from Roumania, after the new commercial treaty with the last two 
nations, the proportions changed considerably, Roumania alone sending 29,000 tons in 
1909. 

Almost the whole of the Italian industry is in the hands of one company, and the 
production is very small and almost stationary. 

The consumption of petroleum by different countries is quite different proportionately 
from the production, as is shown in the following Table, which gives the mean consump- 
tion per inhabitant in 1904 : 



United States .. 

Germany 

England . . 

France 

Russia (140,000,000 inhabitants) 

Japan . . . 



Total consumption 

Tons 
2,016,700 

970,600 
520,933 
312,210 

1,050,787 
299,370 



Annual consumption 

per inhabitant 

Kilos 

25-21 
16-72 
11-84 

8-22 

7-51 

6-65 



1 In 1910 the production was 1,352,300 tons, 339,300 tons of distilled petroleum and 125,750 tons of benzine 
being exported. In 1903 the refineries of Roumania treated altogether 314,748 tons and in 1904 391,387 tons of 
crude petroleum, which yielded 62,218 tons of benzine, 109,510 tons of lighting oil, 30,214 tons of mineral oil, and 
173,661 tons of residues. In 1909 Koumania exported 420,000 tons of petroleum benzine, and mineral oils. 



ORGANIC CHEMISTRY 



Roumania . . . 
Austria -Hungary . . 
Italy . . . . 
India (300,000,000 inhabitants) 
ghina (300,000,000 inhabitants) 



Annual consumption 
Total consumption per inhabitant 

Kilos 
4-50 



Tons 

27,025 

215,546 

73,000 

503,930 

254,464 



4-31 
2-21 

1-70 

0-85 



The units of measure of petroleum in different countries have already been given on 
p. 58. 

In view of the enormous and increasing consumption of petroleum, it may be interesting 
to know how much longer the known stock of petroleum in the earth will last. According 
to the calculations made in 1909 by the Geological Survey Office, the known deposits 
of petroleum would last until 1990 if the annual consumption remained at its present 
amount, but if the consumption increases in the same proportion as it has been doing 
during the last few years, the deposits will be exhausted in 1935. 

The price of rectified petroleum at Batoum is about 7s. 2d. per quintal, and the trans- 
port to Genoa Is. 5d., and, making allowance for all taxes, Russian petroleum costs at 
Genoa 16s. per quintal, including the cask ; the American costs 16s. I0d., and at the 
present time Russian petroleum is beginning to oust the American product from the 
European markets. In the free port of Hamburg, Russian and American petroleums 
cost 16s. Wd. per quintal in 1879, 13s. Id. in 1890, and 14s. Q%d. in 1904. 

TESTS FOR LIGHTING PETROLEUM. A good petroleum is limpid and colourless, 
does not turn brown with sulphuric acid (sp. gr. 1-53), and has a specific gravity of 0-820- 
0-825 (Russian) or 0-780-0-805 (American) ; the specific gravity is determined with an 
aerometer at 15 (corrected by 0-0007 for each degree) and referred to water at 4. It 
should not have an acid reaction ; when 10 c.c. of the petroleum is dissolved in a mixture 
of alcohol and ether previously rendered neutral to phenolphthalein, an immediate violet 
coloration should be produced on addition of a single drop of N/10 alcoholic caustic soda. 
When subjected to fractional distillation in the Engler flask (p. 66), it should not yield 
products distilling below 110, only 5 per cent, or at most 10 per cent, up to 150, and 
less than 10 per cent, or at most 15 per cent, above 300 ; in the distillation products 
the difference in specific gravity between Russian and American petroleums is increasingly 
marked. American petroleum is distinguished from the Russian (see p. 62 et seq.) also 
with the refractometer and by the different solubilities of the fractions of equal specific 
gravity in a mixture of chloroform and aqueous alcohol (Riche-Halphen test) 1 . The 
viscosity determined with the Engler viscosimeter (see later, Mineral Oils) should not be 
greater than 1-15 at 20. The luminosity is determined with the Bunsen photometer 
(p. 56) and, in general, 3-5-5 grms. are consumed per candle-hour. 

The determination of the temperature at which a petroleum gives off inflammable 
vapours is of great importance, and in order to obtain concordant results, the Abel apparatus 
modified by Penski (Figs. 91 and 92) is employed in all laboratories. The petroleum to 
be examined is placed in a brass receiver, G, up to the level-index, h ; the cover, D 8, 
carries a thermometer, t, which dips into the petroleum, and a clockwork mechanism, 
T b, which, when it is released (by a lever, h), opens automatically a small window in the 
cover ; at the same instant a small oil-flame passes through the window and is immediately 
withdrawn, the window then closing. The petroleum receiver is surrounded by an air- 
chamber, A, which is heated to 55 in the reservoir, W, regulated by the thermometer t 2 . 
For every 0-5 increase of temperature of the petroleum, the spring is released, this being 
continued until the flame ignites and explodes the mixed petroleum vapour and air. 
The slight explosion sometimes extinguishes the flame. The temperature shown at this 

1 Of each fraction with specific gravity higher than 0-760, 4 grms. is weighed into a beaker, and from a burette 
a mixture in equal parts of anhydrous chloroform and 93 per cent, alcohol is run in until the tuibidity fiist foimed 
suddenly disappears : 

Density . . . . 0-760 0-770 0-780 0-790 0-800 0-810 0-820 0-830 0-850 0-880 
American petroleum (cubic 

centimetres solvent). . 4-3 4-6 5-2 5-9 6-6 7-7 9-5 11-3 

Russian petroleum (cubic 

centimetres solvent). . 4-0 3-d 4-1 4-2 4-0 4-2 4-5 5-0 6-4 11-9 

Italian petroleums behave like the Russian, but this reaction does not serve to distinguish between the other 
European petroleums (Utz, 1905). 



FLASH-POINT OF PETROLEUM 



73 



moment by the thermometer ^ is that of inflammability (flash-point), which is, however, 
influenced by the atmospheric pressure and should be corrected by + 0-035 for every 
mm. of pressure above 760 mm. 

In Italy, Germany, and Austria the sale of petroleum for lighting purposes is prohibited 
if it shows a flash-point below 21 in the Abel apparatus ; otherwise explosive vapours 
could be formed in ordinary lamps, even at 30 or 32, which would be dangerous. 
A petroleum inflammable at above, 60 (Abel) cannot be used for lamps. 

A rough-and-ready test to detect if a petroleum is dangerous consists in pouring a 
little into a glass and throwing into it a lighted match ; if the latter is extinguished, the 
petroleum is safe. 





FIG. 91. 



FIG. 92. 



The illuminating power is determined with the Lummer and Brodhun photometer 
(see Fig. 77, p. 56). To determine the moisture or water, which does not separate well in 
the distillation of certain Calif ornian petroleums, Robert and Fraser (1910) proposed 
adding calcium carbide and measuring the quantity of acetylene formed, this depending 
on the amount of water present. 

TREATMENT OF CRUDE BENZINE 

The portion of crude petroleum distilling below 150 forms crude benzine, which can 

be separated by fractional distillation into various qualities for different commercial uses. 

The crude benzine is redistilled in small horizontal or vertical boilers, usually heated 

by superheated steam either in a jacket or in closed coils inside the boiler, the condensed 

water being collected outside the boiler. 

In some cases moderate fire-heat is used in addition. 

When there are many volatile products, an apparatus similar to that used in the 
rectification of spirit is employed. Such a system of rectifying columns is to-day in general 
use, and the condensation of the vapours and the cooling of the condensed benzine are 
effected by the crude benzine, which is thus fractionated and fuel at the same time 
economised. 

A special apparatus for condensation and rectification, devised by Veith, consists of 
five iron double-walled cylinders (with water-circulation), connected in series and .ter- 
minating in a sixth cylinder containing a coil with many turns for the condensation of 
the vapour from the preceding cylinder. The coil is cooled by ice and cold water, which 
then passes successively into the jackets of the other five cylinders and gradually becomes 
heated. These five cylinders are full of pure iron turnings free from oil. The vapours 
from the boiler in which the benzine is distilled pass through cylinders 1-5, in each of which 



74 ORGANIC CHEMISTRY 

that part condenses which is liquefied at the temperature of the water circulating in the 
jacket. 

The least volatile products condense in the first cylinder and the most volatile ones in the 
final coil. At the bottom of each cylinder is a pipe with a tap communicating with a tank. 

The apparatus for distilling and rectifying benzine are so constructed that the vapour 
above the boiling liquid which is mixed with air is separated from the liquid, e.g. by metal 
gauze, so that in case of fire or explosion the liquid does not ignite. 

Baku petroleums give only 0-2 per cent, of benzine, those of Grosny (Russia) about 
4-5 per cent. In 1902, 341,000 tons of naphtha were distilled at Grosny, 14,000 tons of 
benzine (about 4 per cent.) being obtained. Pennsylvanian petroleums give up to 12 per 
cent, of benzine, and those from Campina (Roumania) 3-5 per cent. ; a petroleum from 
Anapa (Caucasus) gave 28 per cent. Italian petroleums from Emilia yield 30-35 per cent, 
of benzine. 

After the fractional distillation of the benzine the separate portions are often refined 
by treating with concentrated sulphuric acid mixed with 0-2 per cent, of potassium 
dichromate and 0-01 per cent, of lead oxide. Fuming sulphuric acid also gives good 
results, but animal charcoal and magnesium hydrosilicates are not very satisfactory. 
The treatment is carried out in closed vessels with mechanical stirrers, the use of com- 
pressed air being inapplicable here. 

The majority of the benzine is produced at Baku and in Pennsylvania, but some is 
refined in Germany and large quantities are sent to Europe from the East Indies from 
Java, Sumatra, and Borneo ; Galicia and Roumania also yield large quantities. 

The consumption of benzine is to-day tending to increase, not only as a solvent for 
fats (benzine boiling between 60 and 80), but also for automobiles, aeroplanes, and 
dirigible balloons, its calorific value (about 11,000 cals.) being high. That used for cleaning 
fabrics should boil at a higher temperature, otherwise it evaporates too easily and leaves 
an annular mark round the spot (other varieties, see p. 66). 

The consumption of benzine in the various countries of Europe amounted in 1908 to : 
115,000 tons in. Germany, 130,000 tons in Trance, 100,000 tons in England, 10,000 tons 
in the Netherlands, 110,000 tons in Russia, 20,000 tons in Roumania, 10,000 tons in 
Austria and Galicia, and 25,000 tons in other European countries. The United States 
produced 800,000 tons of benzine in 1908 and the Dutch Indies 260,000 tons. 

TREATMENT OF PETROLEUM RESIDUES 
A. Lubricating Oils. B. Vaseline. C. Paraffin. 

(A) LUBRICATING OILS. The crude petroleum residue remaining in the boilers 
at 300 (astatki or masut 1 ) forms a brownish black mass with a greenish reflection, dense 
and sometimes semi -solid at ordinary temperature, and often with a burnt, faintly creosotic 
smell ; it has a specific gravity of 0-900-0-950 and a coefficient of expansion of 0'00091, 
and gives inflammable vapour even at 120-160 ; that of Baku contains no paraffin and 
hence does not freeze. When these residues are discharged from the boiler, in order to 
cool them and so prevent them taking fire they are passed through the tubes which serve 
to heat the crude petroleum before introducing it into the boiler. At Baku the residues, 
which form almost two-thirds of the crude naphtha, are largely used as a combustible for 
the distillation vessels and also for locomotives and marine engines, the calorific power 
being 9700-10,800 cals. and 1 kilo being able to evaporate as much as 14-15 kilos of water. 2 

1 Masut contains, on the average, 87-5 per cent. C, 11 per cent. H, and 1-5 per cent. O ; it has a mean 
specific gravity of 0-91, an ignition temperature of 110 and a calorific value of 10,700 cals. When used 
as a combustible it is gasified, the vapours, mixed with compressed air, burning completely ; it is often burnt 
directly after pulverisation with compressed air or steam. 

In view of the great calorific value of petroleum residues and their increasing production, new outlets have been 
sought for them ; they should have a great future as a substitute for coal in the heating of boilers, steam-engines, 
ships, &c. 

But, as has been already stated, this use of it is diminishing in Russia, although continually extending in 
the United States. In Italy attempts have recently (1911) been made to burn it, after pulverisation, directly 
under boilers, and it can be used advantageously if it does not cost "at the factory more than about 5s. per quintal, 
coal giving 8000 cals. costing 2s. lOd. ; the cost of transport is hence excessive, increasing the price from lOd. 
or 15rf. at the refinery to 5s. in Italy. The Customs duty (Italy) is 20 centesimi (just under 2<J.) per quintal. 

The heavy oils extracted from petroleum residues are largely used for special engines of the Diesel type. 

2 "Cracking" Process. In some cases it is convenient to convert the heavy mineral oils (and also 
the masut) into petroleum for lighting, use being made of the process of cracking. This is based on the fact, 



PETROLEUM RESIDUES 



75 



Utilisation of a great part of these residues was commenced after the first American 
and Scotch samples (from shale oils) were exhibited at the International Exhibition at 
Paris in 1867. In Russia enormous quantities of residues, of almost no commercial value, 
accumulated every year. Their utilisation was initiated in 1876 by the Bagosin process 
for preparing the best lubricating oils (those of Baku are highly valued) by distilling the 
residues by means of superheated steam, so as to avoid the formation of empyreumatic 
odours. 

The distillation is now carried out in long horizontal boilers, since in vertical ones 
which were used at one time the vapours, in contact with the heated walls, give products 
of profound decomposition and of bad odour. Direct-fire heating can be partly used in 
conjunction with internal heating by superheated steam at 220, and the distillation is 
facilitated by carrying it out in a vacuum. 




FIG. 94. 

Fig. 94 shows the plant used by Nobel Brothers at Baku. The condensation is effected 
in long, parallel, slightly slanting pipes, d, d v d z (40-50 cm. in diameter), communicating 
alternately at the ends* The first of these is cooled by air alone, the second by water 
and the third by very cold water that circulates in a coil ; H is an exhaust-pump. At 

established in 1872 by Thorpe and Young, that, when the vapours of heavy petroleums are superheated, they 
yield gaseous hydrocarbons (6 to 8 per cent.) poorer in hydrogen (ethylene series) and lighter liquids which can bo 
used as second quality petroleum. The operation is carried out 
in a vertical boiler (Fig. 93), placed in a furnace so that its 
walls are strongly heated by the hot fumes circulating round 
them. The boiler is not completely filled with masut, so that 
the vapours evolved, coming into contact with the red-hot walls 
above the liquid, are decomposed ; after separation in a de- 
phlegmator of the heavy oil carried over, the vapours are pro- 
gressively liquefied in ordinary condensers or refrigerators, 
yielding solar oil, benzine, &c., whilst the remaining gas is used 
for heating or for gas engines. A mineral oil from Ohio treated 
by this process gave the following products : 25 per cent, of 
benzine (sp. gr 0-650-0-745), 33. per cent, of lighting petroleum 
(sp. gr. 0-800-0-840), 10 per cent, of light paraffin oils for burn- 
ing (sp. gr. 0-854-0-859), 31 per cent, of solid paraffin and 
paraffin oil (sp. gr. 0-870-0-925), and 3 per cent, of coke and 
loss. 

Manufacture of Benzene from Naphtha. Attempts in 
this direction had already been made as early as 1875, and 
later llagosin and Nikiforow, Krey, Laing, Dewar, and 
Redwood attacked the problem, but without practical success. 
Recently Nikiforow appears to have succeeded and he has 
devised a plant for treating 2400 tons of naphtha and pro- 
ducing 262 tons of benzene. He subjects the naphtha to two 
distillations under different pressures, in a retort first at 500 
and then at 1000. In this way 33 per cent, of tar containing 

50 per cent, of aromatic compounds is obtained, together with an abundant supply of gas which serves for 
heating, lighting, and power purposes. After redistillation and rectification of the first of these products, a final 
yield of 12 per cent, of benzene and toluene is obtained, 3 per cent, of naphthalene, 1 per cent, of anthracene, 
and various secondary products. Benzene thus prepared will apparently cosfc-20s. per quintal and the aniline oil 
(used in dyeing) obtainable from it would cost about one-half as much as that on the market in Russia. J. Hausmann 
(Ger.\Pat. 227,178, 1909) also obtains benzene and its derivatives by passing the vapours of" mineral oil into red- 
hot tubes, and into contact with catalytic agents (oxides of iron, lead, and cerium, sulphate of iron, &c.). 




FIG. 93. 



76 



ORGANIC CHEMISTRY 



the bottom of each of these pipes is a discharge pipe for the mineral oil condensates, which 
pass to water-separators ; thus three qualities of oil are obtained in three separate tanks : 
20-25 per cent, of solar oil, specific gravity below 0-890 ; 6-10 per cent, of spindle-oil 
of sp. gr. 0-890-0-900 ; 25-30 per cent, of engine oil, sp. gr. 0-900-0-920, 3-4 per cent, of 
cylinder oil, sp. gr. 0-925 ; 3 per cent, of tar ; and 5 per cent, of loss. The quantity of steam 
consumed varies from 100 to 150 per cent, of the amount of oil distilled and the quantity 
of masut treated every 24 hours corresponds with about double the volume of the boilers. 

A somewhat different apparatus which has also given good results for the distillation 
of tar and of its heavy oils is that made by the firm of Hirzel in Leipzig. The large boiler, 
BV, with a convex base (Figs. 95 and 96) is divided longitudinally by a metal partition, 1, 
which allows the two halves of the boiler free to communicate at the end, 7 ; the distillation 
products enter at the tube 4, connected with the horizontal pipe 5, from which the liquid 
descends to the bottom of the first half of the boiler along the tubes 6 ; the superheated 

steam enters by the tube 3, which 
is forked half-way down the boiler 
and connects with a battery of 
horizontal perforated pipes running 
along the bottom of the boiler. The 
liquid moves slowly in a compara- 
tively thin layer from the first to 
the second half of the boiler, pass- 





Section A.B. C.D. E F. 



EB- 



Section J- 1C. 




FIG. 95. 



FlG. 96. 



ing through the space 7, and issuing at the tube 8 ; the vapours are collected in the 
dome, W, containing perforated discs to condense the drops carried over with the vapours, 
the latter proceeding through the tube a to the rectification or fractional distillation 
apparatus. In 1911 the Hirzel apparatus was also used by a large Italian firm of metal- 
lurgical coke manufacturers and tar distillers. 

All these crude mineral lubricating oils, after being freed from moisture by heating, 
are refined by prolonged shaking with 5-10 per cent, of concentrated sulphuric acid and, 
after decantation of the black acid, with a concentrated caustic soda solution (15 Be.) 
at 60-65, this being followed by washing with hot water. In these refining operations 
8-15 per cent, of the mineral oil is lost. The residues in the boilers, if they are not solid 
coke, bat pasty, are dissolved in benzene as a black varnish for iron, or are used as an 
adhesive in the manufacture of briquettes from coal-dust, or as a combustible. 

According to Ger. Pats. 161,924 and 161,925, it is proposed to treat crude mineral 
oils with a saturated solution of sodium chloride and carbonate, to blow air in for some 
time, and finally to distil in presence of an oxide of manganese. 

To render mineral oils inodorous, or nearly so, they are treated in the hot with formalde- 
hyde, and, after addition of alkali or acid to the mass, a current of steam is passed through 
(Ger. Pat. 147,163). According to Ger. Pat. 153,585, the 20 per cent, of crude mineral 
oil is distilled with superheated steam at 180 in presence of 1 per cent, of aqueous lead 
acetate solution. The distillate is free from sulphur and forms a lighting or gas-engine oil ; 
the residue, after filtration, forms a denser and almost odourless lubricating oil. In some 
cases petroleum is deodorised by agitating with calcium chloride and a small quantity 



DECOLORISATION, ETC., OF OIL.S 77 

of hydrochloric acid, decanting it, shaking with lime to fix the chlorine, and sometimes 
adding a little amyl acetate or essence of fennel ; treatment with soda lye is also resorted 
to, and, better still, both for mineral oils and petroleums, with sodium peroxide. 

Latterly, mineral oils soluble in water have acquired importance for lubricating 
machinery, for greasing textile fibres to be combed, and for watering the streets to 
prevent dust. They are prepared by the Boleg process (Ger. Pats. 122,451, 129,480, 
148,168, 155,288) : the mineral oil is heated in a closed vessel, fitted with a condenser, 
at a temperature of 60-70 or above by means of indirect steam ; at the same time finely 
divided compressed air, after addition of a little caustic soda solution, is injected ; a 
small quantity of resin soap or a sulphoricinate is subsequently introduced, the air- 
current being continued meanwhile, and finally the whole mass is heated under pressure 
in an autoclave. 

Emulsions of mineral oils with water are obtained by addition of pyridine or quinoline 
bases or amino-acids. 

To obtain from dark mineral oils less coloured oils, and in some cases oils as colourless 
as water (e.g. vaseline oils), the oil is passed slowly through wide, shallow (a, bout 30 cm. 
deep) filters, filled with a special American clay (fuller's-earth from Florida) consisting 
of aluminium and magnesium hydrosilicates, previously subjected to slight roasting. 
The slow filtration is repeated several times and completed in filters arranged in series. 
The mineral oil remaining in the filters is recovered by displacing it by heavy tar oil (very 
cheap) and displacing the latter with water. Decolor isation is also effected with bone- 
black or, best of all, by residues from the manufacture of potassium ferrocyanide, which 
exhibit very great decolorising power (50 per cent, more than American clay) ; owing, 
however, to the new methods of manufacturing ferrocyanide, these residues are becoming 
scarcer and more expensive (they contain 30 per cent, of animal charcoal, considerable 
quantities of silica and silicates and a little ferric oxide). The darker mineral oils are 
partly decolorised with sulphuric acid, sometimes together with dichromate. 

Carts are often greased with the so-called consistent fats obtained by mixing 15-23 per 
cent, of calcium soaps and mineral oils with 1-4 per cent, of water (if there is no water 
the mass remains liquid, and if there is not a little free fatty acid emulsification ceases 
after a time and the calcium soap separates). 

In 1909 Germany imported 216,987 tons of mineral oils. Italy in 1903 imported 
24,387 tons of mineral oils (exclusive of petroleum) for engines and steam cylinders, and 
in 1909 the importation (including a little heavy resin and tar oils) was 43,360 tons of 
the value of 450,000, besides 8800 tons of residues from the distillation of mineral oils 
(masut), worth 14,000 (in 1907, 560 tons) ; in 1910, 49,181 tons were imported. In 1910 
England imported mineral lubricating oils to the value of 1,705,366 and mineral oils for 
gas-engines to the value of 262,455. 

REQUIREMENTS IN AND ANALYSIS OF LUBRICATING OILS. Lubricating 
oils serve to diminish the friction between metal surfaces in motion ; by adhering strongly, 
although in very thin layers, to these surfaces they prevent contact between them and 
hence friction and heating without sensible increase of the resistance owing to the internal 
friction of the oil. Lubrication is due partly to chemical phenomena (formation of metallic 
soap?) and partly to physical phenomena not well understood ; in general, where there is 
much pressure the viscous oils are suitable, and in other places liquid oils, although in prac- 
tice mixtures of these two kinds are advantageously employed. Oil for lubricating steam 
cylinders at high temperatures should be resistant to great heat and to the mechanical 
and chemical action of steam, and should not give inflammable products at a lower 
temperature than 320, or 300 where superheated steam is employed ; it should possess 
great adhesive power and viscosity and should not contain resinous or tarry residues. 
No oil resists the action of steam at above 350. The good qualities, which are more or 
less dark, are transparent in the liquid state. The selection for steam cylinders of oils 
viscous at ordinary temperatures is unimportant, as they become as liquid as water when 
hot ; this is seen from a comparison of the following two mineral oils, the numbers giving 
the viscosity in seconds required for the passage of 200 c.c. of oil through the Engler 
viscosimeter (see later). 

at 70 at 100 at 150' at 170" 

Viscosity of sample I 270 116 74 67 

II 835 226 93 73 



ORGANIC CHEMISTRY 



The Russian engine oils are more viscous than the American, but the American cylinder 
oils are more viscous than the Russian. American oils with sp. gr. 0-908-0-920 and 
0-844-0-899 have viscosities almost the same as those of the Russian oils with sp. gr. 
0-893-0-900 and 0-900-0-923 respectively. 

The specific gravities of certain American and Russian oils are as follow : 



Axle oil 
Pale engine oil 
Dark engine oil 
Cylinder oil 



American 

0-908-0-911 
0-920 

0-884 
0-886-0-899 



Russian 
0-893-0-895 
0-903-0-905 
0-900-0-920 
0-911-0-923 



At the foot of the page is given a summary of the criteria laid down by Holde for 
various lubricating oils of good quality and the requirements to be answered by thofo 
supplied to the Italian railways. 1 

Sometimes mineral oils are used in special motors for utilising their high calorific 
value (10,500-11,700 cals.). Sherman and Kropf (1908) found that the calorific value of 




FIG. 97. 




FIG 



mineral oils, and to some extent of petroleums, is inversely proportional to their specific 
gravity. 

The origin and properties of certain mineral oils is sometimes related to their content 
of paraffin, the determination of which is described on p. 86. 

i (1) Oil for spinning spindles. Clear liquids, viscosity (see later, Engler viscosimeter), 5 to 12 at 20, inflam- 
mability (in the Martens-Pensky apparatus), 160 to 200. (2) Oil for ice-machines or compressors. Very fluid ; 
viscosity, 5 to 7 at 20 ; freezing-point below 20 ; inflammability, 140 to 180. (3) Oil for light engines and 
transmission, motors, dynamos. Medium fluidity, viscosity, 13 to 25 at 20 ; inflammability, 160 to 210. (4) Oils 
for heavy engines and transmission. Dense ; viscosity, 25 to 45 to 60 at 20 ; inflammability, 160 to 210. (5) Dark 
oils for locomotive and railway carriages. Viscosity, 45 to 60 (summer), 25 to 45 (winter) ; inflammability above 
140 ; freezing-point, 5 (summer), 15 (winter). (6) Oil for steam cylinders. Very dense or buttery ; vis- 
cosity, 23 to 45 at 50 ; inflammability, 220 to 315. For these buttery oils, the dropping --point is determined 
by the Ubbelohde apparatus (p. 6). 

The authorities of the Italian railways demand Russian oils, since these freeze only below - 10, whilst the 
American ones solidify at ; they must not contain water, that is, they must not froth if heated to 129 ; they 
must give no deposit even after standing for forty-eight hours ; the viscosity must be at least eight times that 
of water, they should be perfectly neutral and should not contain shale iil, resin oil, or. animal or vegetable oil ; 
they should not have thf slightest " drying " properties in the air (smeared on glass), or have a density below 
0-91 or a flash-point below 150-180 ; they must not contain more than 10 per cent, of light oils distilling below 
310 ; when shaken with water, the oil should separate immediately without the water remaining whitish. 

With mineral oils for automobiles it is important to test for resin oils, the procedure being as follows : 5 grms. 
of the oil are heated with 25 grms. of 60 per cent, alcohol to 40-50 on a water-bath, the mixture being well shaken 
until it emulsifies, allowed to cool and filtered. The alcohol is driven off from the filtrate on a water-bath 
and the cold residue treated, drop by drop, with 2 to 3 c.c. of dimethyl sulphate : if resin oil is present, a red 
coloration ii produced. 



VISCOSITY, FLASH-POINT, ACIDITY 79 

For lubricating oils it is important to determine the viscosity, and this is usually 
effected by means of the Engler viscosimeter (Figs. 97 and 98), formed of a brass vessel, A 
(sometimes gilt inside), provided with a cover, A lf through which passes the thermometer, t ; 
at the bottom of the vessel is a platinum tube, a, 20 mm. long and of such dimensions 
that it allows of the efflux of 200 c.c. of distilled water at 20 in 52-54 sees. ; the aper- 
ture can be closed from above by the hard wooden peg, 6. The vessel, A, is contained in 
larger one, B, and the space between the two is filled with water maintained constantly 
at the desired temperature by means of the ring-burner, d, and the thermometer, Z x . The 
dimensions of the apparatus are exactly denned and are shown in millimetres in the figure. 
The mineral oil is introduced into A (clean and dry) up to the level indicated by the three 
points (about 240 c.c.). When the temperature of the oil in A has the desired constant 
value, the flask G is placed under the efflux tube and the peg rapidly removed, the 
exact number of seconds taken to fill the flask to the 200 c.c. mark being determined 
by a chronometer. The time required, in seconds, divided by the corresponding 
number of seconds for water at the same temperature gives directly the degree of 
viscosity. 





FIG. 99. 



FIG. 100. 



The flash-point is determined by the Pensky-Martens apparatus (Figs. 99 and 100), 
which is analogous to the Abel apparatus (p. 73) but without the water-bath, being 
furnished instead with a stirrer with vanes, 6, moved by twisting the metal cord, &', between 
the fingers ; it works similarly to the Abel apparatus, and the small flame, E, applied 
automatically, is fed by a small gas tube, H, and is relighted, every time it is extinguished, 
by another flame by its side. The thermometer, t, is graduated from 80 to 320, and the 
heating is effected by the triple gas-burner, g, so that the temperature rises 5 per minute ; 
observations are made by releasing the spring, at first for every 2 and later for every 
1 rise of temperature. 

The acidity is determined by titrating 50 c.c. of the 100 c.c. of 50 per cent, alcohol 
(neutralised) shaken up with 10 grms. of the mineral oil. 

It is sometimes useful to know if certain more or less dark mineral oils are true refined 
products obtained by the distillation of petroleum residues (masut, &c.), or if they are 
merely the crude residues themselves diluted with more or less mineral oil. Charitschkoff 
(1907) found that the rise of temperature on mixing with concentrated sulphuric acid 
(Maumene number) in a Beckmann apparatus (see Molecular Weights, vol. i.) is 2-2-3-5 
for all distilled products (solar oil and various lubricating oils) and 4-8-5 for all non- 
distilled products (crude naphtha, masut, &c.). 



80 ORGANIC CHEMISTRY 

(.B) VASELINE (or mineral fat). This was prepared for the first time by 
Cheeseborough in 1871 and forms a white, buttery mass constituted almost 
exclusively of various high, saturated hydrocarbons. 

It is prepared, especially in America, by heating certain pale, crude, Penn- 
sylvanian petroleums by direct fire in open boilers, and passing into the mass 
a current of hot air until the desired consistency or specific gravity (0-86-0-87) 
is reached. The mass is then decolorised by passing it, while still hot, re- 
peatedly through animal charcoal or other decolorising agents (see p. 77). 
It is also prepared from the residues of Galician and German petroleum by 
diluting them with benzine and repeatedly refining with concentrated sulphuric 
acid. It melts at 33^0. 

Artificial vaselines are also placed on the market, these being obtained by dissolving 
paraffin or cerasin (see later) in paraffin oil ; they can be distinguished from the natural 
vaselines, the latter being sticky and ropy and the former not. At 60 the viscosity 
(Engler) of the natural vaselines is 4-5-7-5, and that of the artificial ones little more than 1 ; 
the latter contain 11-35 per cent, and the natural vaselines 63-80 per cent, of paraffin, 
insoluble in 98 per cent, alcohol at 0. The natural vaseline after solution in ether and 
precipitation with alcohol forms a sticky mass and the liquid remains turbid ; the artificial 
variety, on the other hand, is precipitated in flocks and the liquid is left clear. 

Gelatinised oil of vaseline, also prepared nowadays, is transparent and does not deposit 
paraffin, even if added in considerable quantity ; it is obtained by heating vaseline oil 
(sometimes with a little sulphuric acid) at about 200 and adding, at a certain moment, a 
small quantity of soap. 

For the decolorisation of vaseline and oil of vaseline see above. 

Vaseline is used in pharmacy for the preparation of unguent medicines, 
also for the preparation of lubricants, and, in large quantities, for coating 
metallic articles to preserve them from rusting and oxidation ; it is also used 
in the manufacture of smokeless powder. 

(C) PARAFFIN. This was first found in petroleum by Fuchs in 1809 
and Reichenbach obtained it from wood-tar in 1830, and showed its great 
importance as an illuminant. 

It was obtained later by distilling lignites and bituminous schists. To-day it is largely 
prepared also from the denser American mineral oils (0-8588 and upwards), which on 
cooling deposit scales of paraffin. 

For this purpose an apparatus consisting of three vertical concentric cylinders is 
used ; in the inner and outer ones circulates a non -solidifying freezing solution, which 
has a temperature of -20 and serves to separate the paraffin from the mineral oil in the 
middle cylinder. According to J. Weiser (Ger. Pat. 226,136 and 227,334), paraffin is 
obtained from petroleum and tar residues by dissolving them in hot benzine and glacial 
acetic acid ; on cooling, the solutions deposit paraffin, cerasin, or ozokerite. To free the 
flakes of paraffin from the adhering oil the cold mass is pressed in filter -presses (up to 
15 atmos.) and the cakes thus formed are finally squeezed in hydraulic presses, as is done 
in the case of stearine (see this) ; the blocks of paraffin are then spread out in a warm 
chamber, where the last traces of coloured oils flow away. In the Weiser process the 
hydraulic presses are replaced advantageously by filtering tubes wound round with linen ; 
the paraffin from the filter-press is broken up and forced into these tubes, being afterwards 
removed by steam and sent to the sweating chamber. 

Hard paraffin melts at 54-60, has sp. gr. 0-898-0-915, and forms a white, 
translucent mass used for the manufacture of paraffin candles ; it is soluble 
in ether or benzene, insoluble in alcohol, acetic acid, and acetone. Soft paraffin 
with m.pt. 42-48 and sp. gr. 0-88-0-89 is used as an adjunct in wax and 
stearine candles, to impregnate wooden matches, in dressing textiles and as a 
preventive of frothing during the concentration of saccharine juices (see Sugar) ; 
it serves also as an insulator of electrical conductors and as a cold bath in the 
manufacture of hardened gla^s. 



PYROPISSITE 81 

Most of the paraffin and paraffin oil is obtained from ozokerite (see later), 
the tar distilled from the lignites of Saxony and Thuringia (pyropissite) and 
from the bituminous shales of Scotland and Australia, and also from boghead 
coal. 

I. PYROPISSITE is a special and interesting lignite now almost exhausted, is 
obtained from deposits of oily wood, and is extracted from the mines in Saxony and 
Thuringia in moist (up to 55 per cent, water) more or less plastic masses which feel greasy 
and when dry become friable and readily burn ; it has a dark yellow or brown colour. 
In the dry state it gives up to alcohol 20 per cent, of its weight of a substance, m.pt. 75-86, 
giving paraffin oil on distillation. The composition of a good air-dried pyropissite was 
found to be : water, 33 per cent. ; ash, 6-51 ; C, 43-81 ; H, 6-97 ; N, 0-003 ; O, 8-81. 
When distilled in glass retorts in the laboratory it gives about 66 per cent, of tar, 26 per 
cent, of coke, and 8 per cent, of gas ; sometimes as much as 73 per cent, of tar is obtained. 
The industrial distillation of these lignites is carried out in large vertical refractory retorts, 
8 metres high and 2 metres wide, placed in a suitable furnace so that the external walls 
are heated by rational circulation of the hot gases. Inside the retort are arranged 
numbers of iron capsules, inverted one on the other with a certain distance between, and 
a diameter 12-20 cm. less than that of the retort. The lignite is charged in lumps at the 
top and descends gradually in the free annular space between the walls of the retort and 
the edges of the capsule. When it reaches the bottom it consists of nothing but coke, 
which is occasionally discharged, fresh lignite being introduced at the top ; the gaseous 
products are evolved by a large tube at the top, and the tarry products (tar) flow down 
the walls of the capsules and are collected by a lower tube. The retorts are maintained 
at a dull red heat. 

Lignite tar is brownish yellow to black in colour, has a peculiar odour, and liquefies 
between 15 and 30, giving a greenish fluorescence. Its specific gravity is 0-820-0-935, 
or usually 0-840 at 35. It has an alkaline reaction (from ammonia, ethylamine, &c.) and 
contains about 20-25 per cent, of paraffin. The best lignites give the less dense tars. 
According to the nature of the tar, the paraffin x is obtained from it in the following ways 
(see also Part III, Distillation of Tar) : 

(1) With very dense tars, in order to separate the creosote and certain resinous sub- 
stances more efficiently, vacuum distillation in large direct-fired boilers is resorted to. 
This yields 25-50 per cent, of fatty oils, 50-65 per cent, of crude paraffin, and 7-9 per 
cent, of coke, which is burnt, together with the gases from the distillation, to heat the 
boilers. The mass of crude paraffin is purified with acid and alkali, or with acid and 
subsequent distillation. The more solid part is then separated from the oily part by cooling 
the mass in vessels holding 100-200 kilos, around which circulates a very cold solution 
(the non -solidifying liquids used for ice-machines, see vol. i, p. 231). When the oily or 
buttery part (which is distilled for the extraction of solar oil and second-grade paraffin) 
is separated by filtration from the crystallised paraffin, the cakes of the latter are pressed 
in hydraulic presses at 150 atmos. to remove the 20 per cent, of oil still con tamed in them. 
The solid cakes which remain are yellowish in colour, and are purified by melting them 
several times with 10-15 per cent, of benzine and pressing them at 200 atmos. in a hydraulic 
press. To get rid of the smell of benzine the paraffin is heated in iron cylinders with 
high-pressure steam, the hot paraffin being then passed through the decolorising material 
(animal charcoal, ferrocyanide residues, or magnesium hydrosilicate clay (see p. 77)). 
The small quantity of this material retained by the paraffin is finally removed by 

1 Sow that the deposits of pyropissite are almost exhausted and the paraffin industry of Saxony and Thuringia 
has been subjected to the competition, first, of ozokerite (after 1870), and then (after 1880) to the more serious 
one of the American paraffin extracted from Ohio petroleums which has invaded all the markets of the world 
it has been recently discovered that when pyropissite is distilled a great part of the paraffin is destroyed, much 
better yields being obtained by extracting direct with suitable solvents, which, after evaporation, leave a waxy 
mass ; when this is purified with fuming sulphuric acid, it yields an almost white product of great value the 
montan wax (Bergwachs), similar to cerasin (mineral wax). The remedy for the paraffin crisis of Saxony and 
Thuringia has arrived too late, since the valuable paraffin has been squandered by distillation. Other layers of 
lignite are being worked to-day, and these are extracted in the hot with benzine ; the solution of bitumen extracted 
is first purified by thorough cooling, the paraffins being thus separated while the resins (these are recovered 
by evaporation of the solvent ; they melt at 50 to 60 and form 15 to 25 per cent, of the crude bitumen) remain 
in solution. The bitumen separated in the cold is redissolved in benzine and treated with concentrated sulphuric 
acid, the mass being kept mixed and slowly heated to boiling. Animal charcoal is added and the liquid filtered, 
passed over fuller's-earth (see p. 77), and neutralised by passing in a little gaseous ammonia. After distillation of 
the solvent there remains a yellowish or almost white paraffin melting at 82* to 85 (Ger. Pat. 216,281, 1907) 
II 6 



82 



ORGANIC CHEMISTRY 



filtration through paper, the paraffin being then allowed to solidify in large shallow 
moulds. 

Miss Az has recently suggested the purification of crude paraffin by treating it either 
fused or as powder, between 60 and 70, with a solvent (methyl or ethyl alcohol, acetone, 
or acetic acid or anhydride). The paraffin is insoluble and the impurities soluble in these 
solvents. Paraffin thus purified appears to be of better quality than that purified in the 
ordinary way. 

The tar is sometimes distilled with superheated steam ; in other cases only the benzines 
(photogens) and the light oils are distilled, the residue being cooled to a low temperature 
and the solid paraffin which separates centrifugated to eliminate the tar and heavy oils. 
When the tars are very dense (above 0-900) Krey finds it convenient to distil them under 
a pressure of about 10 atmos., thus raising the temperature to 400-450. This yields 
60 per cent, of distilled oil of sp. gr. 0-830, which is largely used for the preparation of 
oil-gas (see p. 57), 10 per cent, of gas, and 30 per cent, of residual oily tar. 

(2) With light and very pure tars a greater yield of paraffin is obtained more cheaply 
by treating the tar directly with concentrated sulphuric acid, washing with water, and 
subjecting to fractional distillation over calcium hydroxide. Crystallisation, pressing, and 
bleaching are carried out as described above. 

The following scheme shows the different operations and the final yields in a tar 
distillation (the brackets unite products which are worked up together, generally by 
distillation ; the ultimate products are shown in italics) : 

Tar 

(sp. gr. 0-830-0' 



Crude oil 



Crude solar oil Red oil Pasty mass I 



Crude paraffin 



Expressed oil 10 % paraffin I 







(m.pt. 54-60 


Crude solar oil Red oil Pasty r 










12 % (sp. gr. 0-860-0-880) 





2 % photogens 

(sp. gr. 
0-800-0-810) 



10 % solar oil 

(sp. gr. 
0-825-0-830) 



10 % yellow oil solar oil 

(sp. gr. residues 

0-850-0-860) 



3 % fatty oil 

(sp. gr. 
0-880-0-890) 



1 % pasty distillate 
(m.pt. 30-38) 



i 
20 % dark paraffin oil 

(sp. gr. 
0-890-0-920) 



I 

4 % soft paraffin 
(m.pt. 42-48) 



Photogen is a species of benzine similar to that of petroleum, but obtained by the 
distillation of wood, lignite, and coal ; it is used in the purification of paraffin, in the 
carburetting of lighting gas, and for removing spots from fabrics. Yellow oil is used for 
the extraction of fats and for cleaning ; red oil (sp. gr. 0-860-0-880) has various uses, and 
serves well for the manufacture of oil-gas (see p. 57) ; the fatty oils and dark paraffin 
oils (0-880-0-925) are used as oil for gas and for making cart-grease 1 ; the yellow and red 
oils (0-880-0-900) are used as thinner lubricants. 

1 Oils for Gas. From the time when gasworks began to mix gas obtained by the carbonisation of bitu- 
minous coal with carburetted water-gas and with oil-gas (in 1905 Germany produced 30,000,000 cu. metres, England 



ASPHALT E, PITCH, BITUMEN 83 

The washing of tar and of its distillates with alkali removes the creosote which is 
liberated by sulphuric or carbonic acid (see Part III). Washing with acid separates 
resinous masses which are set free by diluting the acid mass with water, this removing the 
acid. Distillation of these resinous masses with varying proportions of creosote oil and 
at different temperatures yields goudron or asphalte tar, or artificial bitumen?- which is 
used in the manufacture of impermeable pasteboard for roofing, in rendering woodwork 
and masonry (especially in damp houses) damp-proof, and also in the manufacture of 
ultramarine. 

II. Another important source of paraffin is furnished by the Bituminous Schists, 
which are especially abundant in the Lothians in Scotland. In 1848 Young and 
Meldrum began to work and purify a special oil issuing from the surface of the soil in 

500,000,000 cu. metres, and the United States 1,550,000,000 cu. metres of carburetted water-gas), the use of mineral 
oils for carburetting the water-gas and tor producing oil-gas has increased considerably. These oils for gasifying 
are obtained partly by the distillation of lignite and shale tars (see pp. 116, 119), but more especially by the 
distillation of petroleum residues (solar oil, intermediate to true petroleum and lubricating oils). The price of 
these oils increases with the narrowness of the temperature limits within which they boil ; these limits are usually 
100 apart and it is of no consequence whether they be 200" and 300 or 250 and 350 ; they should contain less 
than 25 per cent, of unsaturated hydrocarbons (soluble ill concentrated sulphuric acid of sp. gr. 1-83), otherwise 
they give too much tar and coke on gasification ; they should contain not more than 30 per cent, of creosote, but 
a high proportion of paraffin is advantageous. In the United States 600,000 tons are consumed annually ; about 
220,000 tons (in 1906) are imported into England, and about 4153 tons of mineral oils (sp. gr. 0-83-0-83) into 
Germany for the carburetting of water-gas ; but Germany itself produces a further quantity of about 300,000 
tons of oil for gasifying, 13,000 tons being used for producing oil-gas on the railways, and 9000 tons for mineral- 
oil engines. For the carburetting of gas these oils should cost less than 9s. 6rf. per quintal. 

Asphlate, Pitch, and Bitumen. When tar from the distillation of wood (or lignite) is heated until all 
the volatile products are eliminated, there remains a black mass which, when cold, assumes a glassy consistency 
and forms pitch, used particularly for caulking ships, for preparing shoemakers' thread, and for making cements 
impermeable to water, &c. 

When coal-tar is completely distilled it leaves a more or less hard black residue coal-pitch which is used 
for ordinary asphalting and for making varnishes, lacs, and coal briquettes (see vol. i, p. 369). Pitch is also 
prepared expressly by prolonged heating of tar in a current of air or with sulphuric acid. 

Bitumen (mineral pitch) bears sometimes the unsuitable name, natural asphalte, and forms a fragile, blackish 
brown mass, which, on heating, softens between 100 and 135 ; it has the sp. gr. 1-10-1-20 and the hardness 2. 
It burns readily with a very smoky flame, is insoluble in water, alkali or acid, slightly soluble in alcohol or ether 
and readily soluble in benzene, carbon disulphide and turpentine (in which it ceases to be soluble after exposure 
to light, and is hence used in photo-lithography). The best bitumen is found at the surface of the Dead Sea in 
Palestine, and in greater quantities at the Pitch Lake in the island of Trinidad ; it abounds also in Syria, Utah, 
Venezuela, and Cuba, and at Dax (France). That of Trinidad is the best and contains 40 to 50 per cent, of pure 
bitumen and 30 per cent of mineral substances, the remainder consisting of organic substances and water. It 
is roughly refined on the spot by melting at 160-170 in open vessels to separate part of the mineral substances, 
the product thus obtained containing 56 to 58 per cent, of pure bitumen, having the sp. gr. 1-40-1-43 and softening 
at 85 J -95 ; the portion soluble in petroleum ether bears the name petrolene. The amount of change, or efflor- 
escence, which bitumen will undergo under the action of air and light can be estimated by determining the 
proportions of carbenes present, i.e. the products insoluble in carbon tetrachloride but soluble in carbon disulphide. 
Pure bitumen is used for making black sealing-wax, black lacs and varnishes, and also lamp-black ; the lower 
qualities serve for coating wooden structures (boats, telegraph poles), for cardboard, for roofs, and damp 
walls, &c. 

In order to distinguish natural from artificial bitumen, about 1 grm. of the substance is heated to 200, cooled, 
powdered, and treated with 5 c.c. of 80 per cent, alcohol ; if the latter turns yellow and exhibits fluorescence, 
artificial bitumen is indicated, whilst if the alcohol remains almost colourless, the bitumen is natural. 

By the term asphalte (natural) is meant minerals, rocks, and earth containing bitumen : gravelly stones impreg- 
nated with bitumen, as has been mentioned above, are treated for the extraction of refined bitumen by heating 
with water, whilst calcareous bituminous stones containing 5 to 14 per cent, (sometimes 20 per cent.) of pure 
bitumen, are used for the preparation of asphalte mastic by powdering and fusing them homogeneously with 
a certain -quantity of bitumen. This mastic is cooled in moulds and is used directly for paving streets and 
terraces, either alone or mixed with fine sand or gravel. Powdered asphalte can also be used for paving, by 
spreading it out and compressing it with heavy cast-iron double rollers heated inside. 

In California, large quantities of artificial asphalte are prepared by prolonged injection of air into dark mineral 
oils (sp. gr. 0-9333 to 0-9859) heated at 650. Fusion of colophony at 250 and addition of sulphur yields an 
asphalte which is similar to that of Syria and is used in photography. 

Natural asphalte occurs abundantly near Neuehitel, in the Department of Ain (France), in the neighbourhood 
of Hanover, and at Lettomonapello in Italy (the product of this locality is worked at S. Valentino, near Chicti). 

Statistics and Prices. Pitch : Italy produced 4820 tons of the value 9600 in 1909 ; England ex- 
ported 30,000 tons in 1909 and 36,000 tons in 1910, and imported 8000 tons in 1909 and 12,200 tons in 1910 ; 
Germany imported 39,251 and exported 22,387 tons in 1908, and imported 28,434 and exported 34,816 tons in 
1909. 

Asphalte: In 1909 Italy produced 111,067 tons of asphaltic rock, 26,588 tons of pulverised asphaltjc rock, 
8250 tons of artificial asphalte (obtained by mixing the coke remaining from the distillation of tar with sand 
&c.) and 731 tons of compressed asphalte bricks. This production takes place mainly in Central Italy and in 
Sicily (at Kagusa di Siracusa and Modica ; the asphalte rocks of the latter locality, according to A. Coppadoro 
(1910) contain 7 to 14 per cent, of bitumen and 82 to 89 per cent, of calcium carbonate). In 1909 Italy exported 
a total of 21,978 tons (of the value 132,000) of these substances under the name solid bitumen (27,175 tons in 
1906 ; 26,036 tons in 1907 ; 24,158 tons in 1908). In 1908 Germany imported 130,062 tons (98,370 tons in 1909) 
and exported 13,280 tons (14,200 in 1909) ; it produced 103,000 tons in 1905 ; 89,000 tons in 1908 (value 40,000), 
and 77,500 tons in 1909. Trinidad exported asphalte to tho value of 115,800 in 1905 and 133,200 in 1906. 

The price of tar is 6*. 7d per quintal : Archangel pitch I, 22* 5d. ; Swedish pitch, 18s. 5rf. ; coal pitch, 4*. 
to 4s. lOd. ; lignite pitch, 4, Wd. to 6*. 5rf. ; steannc pitch, 14s. 5rf. to 28s. lOrf ; Syrian asphalte I, 68s. ; asphnllo 
in fine powder, 140s. 



84 ORGANIC CHEMISTRY 

Derbyshire, and, having exhausted this deposit and not finding others, they succeeded in 
preparing mineral oils, which had been already introduced for illuminating purposes, by 
distilling cannel coal, which gave much lower but remunerative yields. 

In about 1860 they discovered that the interesting Scotch deposits of boghead coal 
gave a yield of oil much greater than cannel coal, and in 1864 and 1866 were erected the 
two works at Bathgater and Addiwell, which became world famous. The deposits of 
boghead coal were exhausted in four or five years, and were then replaced by the more 
abundant although less fertile deposits of bituminous schists (shales) in which Scotland is 
so rich. The invasion of American petroleum in about 1880 created a serious crisis in 
this industry, which was partially saved by new and improved technical methods intro- 
duced by engineers and chemists, especially by Henderson ; the by-products were more 
completely utilised, the furnaces improved, fractional distillation apparatus brought into 
use, the ammoniacal liquors utilised, the tar, coke, gas, and final residues employed as fuel 
and the labour reduced to a minimum ; the mineral oils came to occupy a secondary 
position, attention being paid to the production of paraffin and high-class lubricating 
oils for engines. 

In France these bituminous schists, which abound in the basin of the Autun and at 
Buxiere-les-Mines, were first worked in 1837 by Selligne in consequence of the studies 
of Reichenbach (1830), and the industry became a flourishing one about 1860 ; in 1864, 
128,550 tons of shale were distilled, producing 4750 tons of crude oil, destined principally 
to prepare oil-gas in the large towns. The invasion of American petroleums also over- 
threw this industry, which is now only partially supported by the Customs duty. 

A bituminous schist from Midlothian (Scotland) gave on analysis : 20 per cent, 
carbon, 0-7 per cent, nitrogen, 1-5 per cent, sulphur, the rest being mineral matter ; it 
gave up nothing soluble to ether. 

The industrial distillation is carried out in batteries of vertical retorts arranged in a 
furnace and heated also internally with superheated steam. The products of distillation 
are condensed with apparatus similar to that used for illuminating gas, the residues from 
the retorts, containing as much as 12 per cent, of combustible substances, being burnt 
in the furnaces. The distillation lasts from 4 to 6 hours, or, for large retorts holding 2 tons, 
24 hours. The yield consists of about 4 per cent, of gas, 8 per cent, of ammoniacal liquor 
(ammonium carbonate), 12 per cent, of crude oil, 76 per cent, of residue. The crude oil 
contains less than 0-03 per cent, of sulphur ; the gas evolved contains 21-23 per cent. 
CO 2 ; 1-4 per cent. CO ; 13-24 per cent. H ; 1-6 per cent, of heavy hydrocarbons ; 8-20 
per cent. CH 4 ; 1-2-4 per cent. O ; and 35-43 per cent. N. 

The crude oil is dark green and has a sp. gr. 0-865-0-885, and is semi-solid at ordinary 
temperatures owing to the paraffin present. 

This oil is treated by virtually the same methods as are used for lignite tar, that is, 
by continuous distillation in a current of steam, so as to obtain purer products. The 
first distillation gives ': green naphtha (0-753) and green oil (0-858), which are purified by 
acid and alkali and then redistilled : the first gives commercial mineral oil (also solar 
oil) and the second light oils and paraffin, which is separated by cooling from the blue oil, 
which serves as a good lubricant when refined. The paraffin is purified by the process 
given above (paraffin of lignite tar). 

A ton of bituminous schist (of the value of 12s. 9%d.) yields about 8 kilos of naphtha, 
115 kilos of crude oil (green oil), and 13 kilos of ammonium sulphate. From 100 kilos 
of green oil are then obtained 31 kilos of burning oil, 13 kilos of lighting oil, 11 kilos of 
midlle oil, 15 kilos of paraffin, and 15-20 per cent, of loss, the remainder being coke 
or tar. 1 

1 Ichthyol is an oil obtained by the dry distillation of a bituminous shale occurring abundantly in the 
Tyrol (at Seefeld), and at Besano (Varese), and Melide (Switzerland). On distillation it yields, besides illuminating 
gas, 5 to T per cent, of crude, utilisable ichthyol (for the Melide shales) containing 5 per cent. (Besano) or 10 per 
cent. (Seefeld) of combined sulphur and 6 to 7 per cent, of nitrogen. On distillation, these shales lose 30 to 40 per 
cent, of their weight. The Besano oil is richer in pyridine bases than that of Seefeld, Which contains 1 per cent, of 
them (Baumann and Schotten, Contardi, and Malerba). 

Treatment of this oil with concentrated sulphuric acid yields ichthyolsulphonic acid containing 10 to 15 per 
cent. S (like sulphoricinates) and forming salts (ichthyolsulphonates) with soda or better with ammonia, which are 
used in the cure of skin diseases. Ammonium ichthyolsulphonate (C 2 2H3eO e S 3 (NH.,) 2 ?), which commonly 
bears the name of ichthyol, forms a dense, reddish brown liquid, soluble in water, and its solution gives a black 
resinous deposit with HC1 and yields NH 3 when treated with KOH. 

When distilled with steam (or treated with hydrogen peroxide) ichthyol loses its unpleasant odour, the deodorized 
product being termed dvsifhthyol. Of the many other derivatives (and substitutes, e.g. thyol, obtained by 
treating tar oils with sulphur), mention may be made of ichthyoform (blackish brown, inodorous), prepared by 



OZOKERITE 85 

The oily schists of Australia (77 miles from Sydney) give, on distillation : 68 per cent, 
of oils, 14 per cent, of gas, 11 per cent, of crude paraffin wax, and 7 per cent, of ash. 

In 1873, 524 tons of oily shales were treated in Scotland ; in 1893 about 2,000,000 
tons, and in 1909 3,000,000 tons, giving 280,000 tons of crude oil. The Scotch shale-oil 
refineries produced in 1908 90,000 tons of burning oil, 16,000 tons of engine oil, 40,000 
tons of gas-oil, 40,000 tons of lubricating oil, 25,000 tons of paraffin wax, and 60,000 tons 
of ammonium sulphate. In 1908 134,163 tons of bituminous shale of the value 72,400 
were produced in Italy. In France 219,000 cu. metres were distilled in 1890. 

In Germany 80,000 tons of lignite tar (corresponding with 600,000 tons of lignite) 
are distilled annually, and the products obtained (9000 tons of paraffin wax two -thirds 
hard and one-third soft 5000 tons of solar oil, and 3500 tons of heavy oil) have a value 
of about 880,000. 

Tar can be purchased from the lignite distilleries at little more than Wd. per quintal, 
and, treated as above, yields 14s. 5d. to 16s., taking as the average selling prices per quintal : 
paraffin wax, 3 12s. ; solar oil, 10s. 5d. ; yellow oil of paraffin, 12s. Wd. ; dark oil of 
paraffin, 10s. 5d., which are about 25 per cent, less than the market prices. 

III. The third source, one of the most important, of paraffin wax is Ozokerite 
(or mineral wax). It is found in England, Russia, and America, but the 
deposits of greatest industrial and historical importance are those of Galicia 
(Boryslaw, Pomiarki, Starunia, &c.), where it occurs in seams as much as 
a metre in thickness. It was discovered by Doms when searching for petro- 
leum, and from 1860 to 1870 was worked by the Landesberg process for the 
extraction of paraffin wax, which competed keenly with that of Saxony and 
Thuringia (from lignite) ; in 1870, Pilt and Ujhelyi found that simple treat- 
ment of ozokerite with concentrated sulphuric acid, followed by decolorisation 
with animal black, yields cerasin, a product of greater value than, and similar 
to, beeswax. 1 In the State of Utah, the industrial treatment of ozokerite 
was begun in 1888, and in 1890 already yielded as much as 600 tons of crude 
cerasin. 

Ozokerite forms an amorphous mass of a yellow, brown, greenish, or black 
colour and of varying consistency ; the harder varieties show a fibrous fracture ; 
the specific gravity is 0-85-0-95, and the m.pt. 55-110 (usually between 
60 and 79) ; it contains 85 to 86 per cent, of carbon and 14 to 15 per cent, 
of hydrogen, and hence consists principally of paraffins, together with a 
small proportion of defines ; it is soluble in benzine, turpentine, petroleum, 
ether, and carbon disulphide, but only slightly so in alcohol. It forms an 
excellent electrical insulator and can be used in place of gutta-percha. 

According to Hofer, ozokerite has been formed by the slow evaporation, 
during many centuries, of petroleum rich in paraffin. 

On distillation, it yields : 2 to 8 per cent, of benzine, 15 to 20 per cent, 
of naphtha, 36 to 50 per cent, of paraffin wax, 15 to 20 per cent, of heavy 
oils, and 10 to 20 per cent, of residual solids. 

STATISTICS AND PRICE OF PARAFFIN WAX. In 1908 fourteen factories in 
Germany treated 70,000 tons of lignite tar, worth about 160,000, and produced 45,000 

treating ichthyolsulphonic acid with formaldehyde and used as an antiseptic for the intestines and instead of 
iodoform for curing wounds . it costs 4 per kilo and ammonium ichthyolsulphonate 1 per kilo. 

1 The material from the mines (shafts 80 metres or more in depth), which contains admixed earth and stones, 
is placed in open vessels holding 300 litres and heated by direct fire heat ; the mineral matter settles to the bottom 
and is separated by decantation. This matter still contains 10 per cent, of wax, which is extracted with benzine ; 
both this and the decanted part form the prime materials treated in the refineries found in all countries. 

The refining is carried out in large iron boilers holding up to 3000 kilos of the crude wax, half a metre being 
left free to take the scum which forms. The fused mass is kept at 115-120 for four to five hours and is stirred 
to liberate all the water ; 15 to 25 per cent, (according to the quality of the wax) of fuming sulphuric acid con- 
taining 78 per cent, of SO, is then added, in a thin stream, to the mass, which is thoroughly stiired meanwhile ; 
the temperature rises slowly to 165 and then to 175, the oxidisable impurities separating as a black mass (asphalte) 
and the excess of sulphuric acid evaporating. The vessel is covered and provided with a draught-pipe to carry 
off the acid vapours. The mass is allowed to cool slowly, being neutralised with residues from the manufacture 
of ferrocyanide, decolorised with animal black and sent to the filter-presses. The mass obtained is still slightly 
yellow and is whitened by further treatment with sulphuric acid. When beeswax is to be imitated, quinoline 
yellow or other coal-tar dye is added. 



86 



tons of oil, 11,000 tons of crude paraffin wax (equal to 7600 tons of the pure wax, worth 
220,000), and 8000 tons of creosote, tar and pitch, of the total value of 450,000 ; about 
1 ,000,000 tons of lignite were distilled and 350,000 tons of coke left. For several years, 
however, the industry has been stationary. The market price of paraffin wax varies some- 
what with its melting-point 1 ; white, m.pt. 38-40, costs 78s. per quintal ; that melting at 
42-44, 82s. 6d. ; at 48-50, 85s. 6d. ; at 56-58, 92s. ; and at 60-62, 5. That used in 
pharmacy, m.pt. 74-76, costs as much as 9 12s. Crude paraffin wax is sold for about 
56s. During recent years, however, the price has diminished considerably owing to the 
great production in Galicia (54,000 tons in 1909 and 62,000 in 1910), whence a considerable 
quantity is exported into Germany even at less than 32s. per quintal. 

In 1909 England imported 53,000 tons (1,126,000) of paraffin, and exported 17,400 
tons (407,024) ; in 1910 the exports were valued at 288,457. 

In 1903 Italy imported 9526 tons of solid paraffin ; in 1905 about 8880 tons ; in 1909 
17,400 tons, and in 1910 19,153 tons of the value of 400,000, in addition to 108 tons of 
cerasin worth 4340. The production of paraffin in the United States has become of 
great importance, the Standard Oil Company having almost the monopoly (95 per cent, 
of the American output) ; the exportation was 75,000 tons in 1905, 85,000 tons in 1909, 
95,000 tons (1,465,800) in 1910, and 97,000 tons (1,409,600) in 1911. From the 
bituminous shales of Scotland 23,000 tons of paraffin wax were obtained in 1910. 

Pure white cerasin resembles wax, melts at 62-80, and has the sp. gr. 0-918-0-922. 
It is used in making candles, in perfumery, and as dressing for textiles. It is subject to 
much adulteration owing to its high price ; the yellow of the first quality, m.pt. 62-63, 
costs 108s. or more per quintal ; the second quality 92s. ; that melting at 68-70 costs 
6, and the white, m.pt. 62-63, 6 12s. 2 

The ozokerite worked in Austria -Hungary in 1877 amounted to 8961 tons ; in 1885, 
13,000 tons ; and in 1894, 6742 .tons. The exportation of cerasin was 3594 tons in 1891 
and 2382 tons in 1895. 

In the United States the production of refined ozokerite, which was 160 tons in 1888 
rose in 1892 to 75,000 tons, of the value of 4;000,000. 

1 The estimation of the paraffin wax in a commercial sample of hard paraffin is made by Holde's method : 
1 grm. is dissolved in a test-tube in ether excess of which is avoided the solu- 
tion cooled to 20 or 21 and an equal quantity of absolute alcohol added ; the 
paraffin is thus separated in flakes, and if the mass is too hard to be filtered, it is 
diluted with the mixture of alcohol and ether cooled to - 20 (see Freezing Mix- 
tures, vol. i, p. 229). The filtration is effected under pressure in a funnel sur- 
rounded with the freezing mixture, the paraffin being washed with the alcohol- 
ether mixture and the washings kept separate from the first filtrate ; the latter is freed 
from the solvent by evaporation, and any paraffin wax that may have been dissolved 
then estimated. The paraffin on the filter is dissolved in hot benzine, the solution 
evaporated in a tared dish, and the residue dried at 105 and weighed ; the per- 
centage of paraffin wax found is increased by 1 to. correct for constant errors of 
analysis. The apparatus used is shown in Fig. 101 ; the solution to be filtered is 
kept cold in the test-tubes immersed in the freezing mixture, 3, surrounded 
by felt, 2 ; the water from the freezing mixture runs off at 5 and that which drops 
collects in 4. 

With soft paraffin wax Eisenlohr's method is used : 0-5 grm. of the substance 
is dissolved in 100 c.c. of absolute alcohol, 25 c.c. of water being added and 
the solution cooled to - 18 or - 20. The separated paraffin is filtered as 
described above and washed with 80 per cent, (by volume) alcohol until the filtrate 
no longer turns turbid on addition of water. It is dried in vacua at 40 until 
constant. 

To detect the addition of even small quantities of cerasin (see above) Graefe 
dissolves 1 grin, in 10 c.c. of carbon disulphide at 20 and treats 1 c.c. of this 
solution with 10 c.c. of a mixture of equal volumes of alcohol and ether. If 
undissolved flocks remain even after heating and subsequent cooling, the presence 
of cerasin is certain ; this result can be confirmed by means of the Zeiss oleo- 
refractometer, paraffin wax at 90 showing 1-5 to 4, and cerasin 11-5 to 13 (Ulzer 
and Sommer, 1906 ; Berlinerblau, 1903). 

A mixture of cerasin and paraffin wax can be detected by the following test : a glass rod 3 mm. in diameter 
in diameter is immersed to a depth of 1 cm. in the fused substance, extracted, allowed to cool and hung in a 
test-tube heated externally with water. If the wax drops above 66, it is pure cerasin, whereas if it drops below 
66 it is regarded as mixed with paraffin wax or as the latter alone. - The dropping-point can also be determined 
with tho Ubbelohde apparatus (p. 6). Addition of colophony is recognised by the add number or saponification 
nnmbw, colophony being saponifiable and cerasin not. 




L 1 

FIG. 101. 



OLEFINES 



87 



(b) UNSATURATED HYDROCARBONS 
I. ETHYLENE SERIES : C H H 2n (Alkylenes or defines) 

Two groups belong to this series, the olefine group, the first member of 
which is ethylene, C 2 H 4 , the succeeding ones being open-chain hydrocarbons 
with a double linking between two carbon atoms, since hydrogen, halogens, 
ozone, &c., can be readily added to them, transforming them into saturated 
compounds of the paraffin series. 

The other group yields additive products only with difficulty, and its 
members are formed of closed carbon-chains (cyclic compounds}. The first 
term is trimethylene or cyclopropane, hexamethylene, and higher compounds 
being known : 

-tL 2 ri 2 

c-c x 

H 2 C< >CH 2 

!_CH, \c-cy 

II., II., 



CH, 



Trimethylene 



Hexamethylene 



The carbon atoms in these last compounds are all in the same conditions 
and cannot be differentiated. The cyclic compounds will be studied in a 
separate section of the aromatic series (Part III). 

The following Table gives the more important members of the olefine 
series (the number in parentheses representing boiling-points under reduced 
pressure) : 





Melting- 
point 


Boiling- 
point 




Melting- 
point 


Boiling- 
point 


Ethylene, C 2 H 4 . . 


-169 


-103 


Decylene, C 10 H 20 . 





172 


Propylene, C 3 H 6 . 





-48 


Endecylene, C 11 H 22 





195 


Butylene (3 isoms.),! , 
OH V 





5 
+ 1 


Dodecylene, C^H^ 
Tridecylene, C^H^ 


-31 


(96) 
233 


41 8 [y 


' 


-6 


Tetradecylene, C^Hog 


-12 


(127) 


Amylene (5 isoms.), 






Pentadecylene, Ci 5 Tl 30 





'247 


C 5 H 10 ; normal - 






Hexadecylene C 16 H 32 


1 4 ( 


274 


amylene 





+ 35 


(Cetene) 


} \ 


(165) 


Hexylene, C 8 H 12 . 





68 


Octadecylene, C^gHgg . 


+ 18 


(179) 


Heptylene, C 7 H 14 





98 


Eicosylene, C 20 H 40 . 








Octylene, C 8 H 16 





124 


Cerolene, C 27 H 54 . 


+58 





Nonylene, C 9 H 18 





153 


Melene, C 30 H 60 . . 


+ 62 






The official nomenclature of the defines is the same as that of the paraffins, 
excepting that the final ane is changed into ene (thus ethylene, which is isologous 
with ethane, is called ethene, and so on ; see also p. 28). 

These unsaturated hydrocarbons differ little in their physical properties 
from the corresponding saturated homologues. 



The first terms up to C 4 H 8 are gases, 



and after C 5 H 10 come 



liquids 



with increasing boiling-points, these gradually approaching one another as 
in the paraffins ; the higher members are solid and, like the paraffins, have 
a sp. gr. 0-63-0-79, are insoluble in water, but soluble in alcohol or ether. 

The chemical properties differ somewhat from those of the saturated 
compounds. Thus, they readily take up HC1, HBr, HI, Cl, Br, I, fuming 
H 2 S0 4 , hypochlorous acid (giving chloro-alcohols or chlorhydrins, e.g. 



88 ORGANIC CHEMISTRY 

CH 2 : CH 2 + HC10 = CH 2 C1 CH 2 OH), hyponitrous acid, ozone, &c., forming 
compounds of the saturated series. 

Cl is added more easily than I, Br occupying an intermediate position, 
whilst HI is added more easily than HBr, and this more easily than HC1. 
With these acids, the halogen is added to the carbon atom with which the 
least hydrogen is combined. 

Ethylene unites with fuming sulphuric acid at the ordinary temperature 
and with the ordinary acid at 165, forming ethylsulphuric acid, C 2 H 5 S0 3 H ; 
with higher compounds, the acid radicle passes to the less hydrogenated 
carbon atom. 

They often polymerise under the action of sulphuric acid or zinc chloride ; 
for example, amylene, C 5 H 10 forms C 10 H 20 , and C 15 H 30 gives C 20 H 40 . 

They are readily oxidisable, for example, with potassium permanganate 
or chromic acid (not with nitric acid in the cold), the chain being then broken 
at the double linking, with formation of oxygenated compounds (acids) con- 
taining less numbers of carbon atoms in the molecule. Careful use of per- 
manganate results initially in the addition of two hydroxyl groups without 
breaking the chain and forming dihydric alcohols (glycols), for example, 
OH-CH CH-OH. 1 

Almost all compounds with a double linking between atoms of carbon 
give Baeyer's reaction, that is they rapidly discharge the violet colour of a 
dilute solution of potassium permanganate and sodium carbonate, with forma- 
tion of a reddish brown flocculent precipitate of hydrated manganese peroxide. 

This reaction is not given by reducing substances like aldehydes or by 
certain aromatic compounds (phenanthrene, &c.). 

All compounds with doubly linked carbon atoms give the ozone reaction 
(Harries, 1905, and Molinari, 1907), that is, when dissolved in a suitable 
solvent they fix, quantitatively and in the cold, the ozone contained in a current 
of ozonised air passed through the solution ; in this property they differ 
from compounds with either a triple linking or a benzene double linking (E. 
Molinari, Ann. Soc. Chim., Milan, 1907, 116). 

METHODS OF PREPARATION. (1) They are formed, together with 
petroleum, in the dry distillation of wood, lignite, coal, paraffin (" cracking," 
&c.). 

(2) By eliminating water from the alcohols, C n H 2w +iOH, by heating them 
with dehydrating agents (H 2 S0 4 , P 2 5 , ZnCl 2 , &c.) ; a stable intermediate 
product is sometimes formed, e.g. ethyl-sulphuric acid, C 2 H 5 -HS0 4 , which 
at a higher temperature gives ethylene and sulphuric acid. Higher alcohols 
and ethers are resolved, merely on heating, into defines and water. 

(3) From saturated halogen derivatives C w H 2n+1 X (X = halogen), 
especially from secondary and tertiary bromo- and iodo-derivatives, by heating 
them with alcoholic potash, or by passing their vapours over heated lime 
or lead oxide, &c. 

C 5 H U I + C 2 H 5 OK = KI + C 2 H 5 -OH + C 5 H 10 . 
The mixed ether, C 5 H U C 2 H 5 , may also be formed to some extent. 

1 From what has been said up to the present, it is obvious that a double Unking does not signify a firmer 
union between carbon atoms ; it is simply a convention. And the breaking of the chain, by oxidising agents, 
at the double linking is to be attributed to the ease of formation of intermediate products (e.g. dihydric alcohols) 
rather than to a less attraction existing between carbon and carbon at that point. Such readiness to react may, 
according to Baeyer, be explained by regarding the affinities of the carbon atom as orientated or grouped at four 
poles arranged like the vertices of a regular tetrahedron (see p. 18 et seq.). If two carbon atoms unite by a double 
linking the poles at the surface of the carbon atoms become displaced and approach one another, so that there 
results a certain tension which tends to restore the poles to their original positions (Baeyer's tension hypothesis of 
valency), and which explains the readiness with which the double linking reacts or opens. After the initial oxidation 
leading to these intermediate products, further action of the oxidising agent, as a general rule, oxidises or breaks 
the chain at a point where oxygen already exists, that is where the oxidation is already begun (see Part III, The 
Hypothesis of the Partial Valencies of the Beniene Nucleus). 



ETHYLENE 89 

(4) From dihalogenated compounds by heating with zinc : 

C 2 H 4 Br a + Zn = ZnBr 2 + C 2 H 4 . 

(5) By electrolysis of dibasic acids of the succinic acid series : 

C 2 H 4 (COOH) 2 = C 2 H 4 + 2C0 2 + H 2 . 

(6) Unsaturated compounds are obtained by heating the condensation 
products of the ketenes (q.v.). 

CONSTITUTION OF THE OLEFINES. In this group it is assumed that between 
two carbon atoms there exists a double linking: H 2 C=CH 2 , H 2 C=CH CH 3 , &c., the 
presence of two free valencies, thus, H 2 C CH 2 or HC CH 2 , being excluded for the 
following reasons : f\ 

In unsaturated compounds the addition of halogen does not take place at a single carbon 
atom, so that ethylene chloride, C 2 H 4 C1 2 , has not the formula CH 3 CHC1 2 , which is that 
of ethylidene chloride obtained from acetaldehyde, CH 3 CHO, by replacement of the 
O by C1 2 (by the 'action of PC1 6 ). Since ethylene chloride is chemically and physically 
different from ethylidene chloride, the former must have the constitutional formula, 
CH 2 C1 CH 2 C1, and the third formula for ethylene, CH 3 CH< is thus excluded. The 
second formula is not probable because, if the existence of free valencies is assumed, they 
could also occur in non-adjacent carbon atoms, and thus give rise, in the higher hydro- 
carbons, to numerous isomerides which have, however, never been prepared (if propylene 
had two free valencies, four isomerides should exist, instead of only one) ; further, the 
addition of halogen always takes place at two contiguous carbon atoms (see Note on 
preceding page). 

Finally, the admission of free valencies in organic compounds is inadmissible in view 
of the unsuccessful attempts to prepare methylene (or methene), CH 2 , for instance, by 
eliminating HC1 from methyl chloride, 2CH 3 C1 = 2HC1 + 2CH 2 <^ ; the two methylene 
residues always condense, forming ethylene, as the two valencies cannot remain free. 

ETHYLENE, C 2 H 4 (Ethene), H 2 C = CH 2 . This is a gas, becoming liquid 
at 103 and solid at 169, or liquid at under 44 atmos. pressure. It 
is very slightly soluble in water or alcohol. It has a somewhat sweet smell 
and burns with a luminous flame ; indeed, illuminating gas, which contains 
2 to 3 per cent, of ethylene, owes part of its luminosity to this gas. When 
mixed with 2 vols. of chlorine it burns with a dark-red flame, carbon being 
deposited and HC1 formed. At a red heat it yields C, CH 4 , C 2 H 6 , C 2 H 2 , &c. ; 
with hydrogen in presence of spongy platinum or, better, powdered nickel at 
300, it is converted into ethane. 

It is prepared in the laboratory by heating alcohol with excess of sulphuric 
acid ; as an intermediate product, ethyl-sulphuric acid is formed, this 
giving ethylene when heated : C 2 H 5 -OH + H 2 S0 4 = H 2 + C 2 H 5 HS0 4 ; 
C 2 H 5 HSO 4 = H 2 S0 4 + C 2 H 4 . Pure ethylene is obtained (1) by passing 
a mixture of carbon monoxide and hydrogen over finely divided nickel or 
platinum at 100 : 2CO + 2H 2 = C 2 H 4 + 2H 2 ; (2) by dropping alcohol on 
to phosphoric acid at 200-220 ; .or (3) from ethylene bromide and a copper 
zinc couple. 

PROPYLENE, C 3 H 6 (Propene), CH 2 =CH CH 3 . This can be prepared by heating 
glycerol with zinc dust or from isopropyl iodide and potassium hydroxide. It is a gas 
which liquefies at 48 and is isomeric with trimethylene. 

BUTYLENES, C 4 H 8 (Butenes). Three isomerides, the a, ft, and y, are known, and are 
obtained by treating normal, secondary, and tertiary butylene iodides respectively with 
potassium hydroxide : 



CH 2 =CH CH 2 CH 3 CH 3 CH =CH CH 3 3 >C =CH 2 

Butene-l (-butylene) Butene-2 (0-butylene) Methylpropene (isobutylene) 

Tetramethylene or cyclobutane is isomeric with the butylenes. 



90 ORGANIC CHEMISTRY 

AMYLENES, C 5 H 10 (Pentenes). Of the various isomerides theoretically possible 
several Have been prepared. By heating fusel oil (of distilleries) with zinc chloride, 
pentanes and various isomeric amylenes are formed which can be separated by means of 
the different velocities with which HI is added to them, or by the property possessed by 
some of them of dissolving in the cold in a mixture in equal parts of concentrated sulphuric 
acid and water, forming amylsulphuric acid, whilst the others either do not react or give 
condensation products (di- and triamylenes). 

CEROTENE, C 27 H 54 , and MELENE, C 30 H 60 , are similar to paraffin, and are obtained 
by distilling Chinese wax or beeswax. 

II. HYDROCARBONS OF THE SERIES, C,,H 2 ,, _ 2 

A. With Two Double Linkings (Diolefines or Allenes) 

Of the few known terms of this series, the first and best investigated is ALLENE, 
H 2 C : C : CH 2 (propandiene) : this is a colourless gas which differs from its isomeride 
allylene in not forming metallic derivatives ; it is obtained by eliminating one atom of 
bromine from tribromopropane by means of potassium hydroxide and the remaining two 
by zinc dust, its constitution being thus rendered evident : 

CH 2 Br CHBr . CH 2 Br-+ CH 2 : CBr . CH 2 Br-+ CH 2 C : CH 2 . 

ERYTHRENE, C 4 H 6 (Pyrrolilene or Butane-1 : 3-diene), CH 2 : CH-CH : CH 2 , is a 

gas found in illuminating gas, and when heated with formic acid gives erythritol. 

ISOPRENE, C 5 H 8 , boils at 37 and is obtained by distilling rubber. On the other 
hand, with concentrated HC1, it condenses, regenerating rubber or forming terpenes, 

riTj 

CioH^g, CifrH-zi, &c. Since dimethylallene, r ,TT 3 ">C : C : CH 2 , gives, with 2HBr, a di- 



bromide, nT , 3 ^>CBr CH 2 CH 2 Br, which is identical with that obtained from isoprene 
U1 3 

CH 2 . 
+ 2HBr, the constitution of isoprene must be : ^.C CH : CH 2 , 

CH 3 / 

The normal isomeride PIPERYLENE, CH 2 : CH-CH 2 .CH : CH 2 (Pentane-1 : 4-diene) 
boils at 42 and is obtained from piperidine. 

DIALLYL, C 6 Hio (Hexine), is prepared by the general reaction the action of sodium 
on allyl iodide which indicates its constitution : 

2CH 2 : CH-CH 2 I + 2Na = CH 2 : CH - CH 2 CH 2 CH : CH 2 + 2NaI. 

CONYLENE, C 8 H 14 (1 : 4-octadiene), CH 2 : CH-CH 2 -CH : CH 2 -CH 2 .CH 3 , boils at 126 
and is obtained from coniine. 

B. Hydrocarbons with Triple Linkings (Acetylene Series) 

The most important members of this series are : 
Acetylene, C 2 H 2 (ethine), HC=sCH, gas. 
Allylene, C 3 H 4 (propine), CH 3 -C=-CH, gas. 

Crotonylene, C 4 H 6 (2-butine or dimethylacetylene), CH 3 -C I C-CH 3 , boils 
at 27. 

Ethylacetylene, C 4 H 6 (3-butine), CH 3 -CH 2 -C : CH, boils at 18. 
Methyleihylacetylene, C 5 H 8 (3-pentine), CH 3 -CH 2 -C I C-CH 3 , boils at 55. 
n-Propylacetylene, C 5 H 8 (4-pentine), CH 3 -CH 2 -CH 2 -C CH, boils at 48. 

Isopropylacetylene,C 6 H. s (3-methyl-l-butine), *:5 3 >CH-C I CH, boils at 28. 

Ui 3 

Several of these compounds (the first three) are formed during the dry 
distillation of coal and other complex substances, and are hence found in 
lighting gas. 

In the laboratory they are obtained by the following methods : 
{a) By electrolysing acids of the fumaric acid series (see later) : 

COOH-CH CH-COOH = H 2 + 2C0 2 + HC ' CH. 



ACETLYENES 91 

(6) By heating with alcoholic potash the halogenated compounds (best 
the bromo-derivatives) C M H 2w X 2 and C n H., w _2X 2 , gradual elimination of 
halogen hydracid (of HBr or, in presence of KOH, of KBr and H 2 O) occurs : 

C 2 H 4 Br 2 = HBr + C 2 H 3 Br HBr + C 2 H 2 . 

In general, starting from the saturated hydrocarbons, C M H 2n + 2 , the action 
of halogen and elimination of halogen hydracid gives an unsaturated hydrocarbon, 
C H H 2n ; addition of halogen to this and subsequent removal of halogen hydracid 
gives a still less saturated hydrocarbon, C M H 2M _ 2 , and so on. 

Elimination of 2HC1 from the compounds C n H 2n Cl 2 , obtained from alde- 
hydes or from certain ketones (methylketones, C M H 2M+1 -CO-CH 3 ) by the 
action of PC1 5 , yields always a trebly linked compound, in which, however, 
one of the carbon atoms is always united to a single, characteristic hydrogen 
atom : C = CH ; for example, acetaldehyde gives ethylidene chloride, 
CH 3 CHC1 2 , which then yields 2HC1 + CH i CH ; while acetone, CH 3 CO CH 3 , 
gives chloroacetone CH 3 -CC1 2 -CH 3 , and this 2HC1 + CH 3 -C = CH, the 
elimination of halogen hydracid never occurring in such a way as to give 
compounds with two double linkings, such as CH 2 : C : CH 2 . 

Acetylene derivatives are also obtained by heating the acids of the pro- 
piolic series (see later), 

Compounds with this characteristic hydrogen atom C^CH have a 
feebly acid character and form solid metallic derivatives (acetylides) when 
treated with an ammoniacal solution of copper chloride or silver nitrate : 
copper acetylide, Cu-C : C-Cu, H 2 0, having a reddish brown colour and 
apparently the constitution, Cu 2 CH-CHO, since with hydrogen peroxide it 
gives acetaldehyde, CH 3 CHO (Makowka, 1908) ; and silver acetylide, AgC : CAg, 
which is white and insoluble in water or ammonia and, in the dry state, is 
extremely explosive, simple rubbing being sufficient to explode it. With 
hydrochloric acid it regenerates acetylene in a pure state. 

The proof that it is the characteristic hydrogen atom which is replaced 
by metals lies in the fact that acetylene derivatives from other ketones (not 
from methylketones) do not give metallic acetylides : 

CH 3 CH 2 CO CH 2 CH 3 >CH 3 CH 2 CC1 2 CH 2 CH 3 > 

2HC1 + CH 3 -C i C-CH 2 -CH 3 . 

Four atoms of a halogen or of hydrogen can be added to the hydrocarbons 
of the acetylene series, saturated compounds being formed ; but as a rule 
only two atoms are readily added, although under the action of light four 
halogen atoms can be added almost always. 

The compounds of the olefine series can, however, be distinguished from 
those of the acetylene series by means of the ozone reaction, since compounds 
with a triple linking do not fix ozone at all (Molinari). 

The hydrocarbons of the acetylene series take up a molecule of water in 
presence of mercury salts, giving rise to complex mercuric compounds, 
which, with HC1, give as final product an aldehyde or ketone ot the satu- 
rated series CH.J-C i CH (aUylene) + H 2 O = CH 3 -CO-CH 3 (acetone) or 
CH i CH + H 2 = CH 3 -CHO (acetaldehyde). This last reaction serves to 
illustrate the transformation of inorganic into organic substances (see later, 
p. 108). 

In the acetylene series, also, condensation or polymerisation is possible, 
three molecules of acetylene, on heating, yielding benzene C 6 H 6 ; three mols. 
of dimethylacetylene, C 4 H 6 , giving, with concentrated sulphuric acid, hexa- 
methylbenzene, C 6 (CH 3 ) 6 , and allylene C 3 H 4 similarly,, yielding trimethylbenzene 
(mesitylene) C 6 H 3 (CH 3 ) 3 . 



92 ORGANIC CHEMISTRY 

In the higher compounds, the position of the triple bond is deduced from 
the oxidation products, since, as with substances with a double linking, the 
breaking of the chain occurs at the multiple linking. 

When certain acetylene derivatives, e.g. XC=ssC-CH 3 , are heated with 
sodium, the triple bond changes its position, the products being sodium 
derivatives of isomeric hydrocarbons, X-CH 2 -C : CH (these give metallic 
acetylides, but the original compounds do not) ; when these are heated with 
alcoholic potash, the reverse change occurs. 

ACETYLENE, C 2 H 2 (Ethine), HC CH. Without having isolated or 
characterised this compound, Davy obtained it in 1839 in a very impure 
condition, by treating with water the product obtained by heating together 
potassium carbonate and carbon, which should yield potassium. Bert helot 
first obtained it pure (and named it) in 1859, by passing ethylene or alcohol 
or ether vapour through a red-hot tube ; he prepared it also by means of a 
voltaic arc passing between two carbons in an atmosphere of hydrogen. In 
1862, Wohler prepared it by treating calcium carbide (obtained by heating 
carbon with an alloy of zinc and calcium) with water. 

It is formed in the incomplete combustion of various hydrocarbons and 
of illuminating gas (e.g. in the flame of a bunsen burner alight at the bottom). 

But the industrial preparation of acetylene has assumed great and unfore- 
seen practical importance since 1870, when it became possible to prepare 
calcium carbide on an enormous industrial scale by means of the electric furnace 
(see Calcium Carbide Industry, vol. i, p. 504) : 

c x 

\] >Ca + 2EUO = Ca(OH) 2 + HC \ CH. 
C/ 

Acetylene is a colourless gas, sp. gr. 0-92 (1 litre weighs 1-165 grm.) with 
a pleasant odour when pure and a disagreeable one when impure (as usually 
obtained). At + 1 under a pressure of 48 atmos. it forms a highly refractive, 
mobile, colourless liquid, sp. gr. 0-451, and, on evaporating rapidly, partially 
solidifies in the form of snow, m.pt. 81. 

One volume of acetylene gas dissolves in 1-1 vol. of water, or in |- vol. of 
alcohol or in 20 vols. of saturated salt solution ; 1 litre of acetone dissolves 
24 litres of acetylene, or 300 litres at 12 atmos., or about 2000 litres at 80, 
its volume being then increased fourfold. Permanganate oxidises it giving 
oxalic acid, and chromic acid acetic acid. 

It is an endothermic compound, requiring for its formation from its elements, 
61,000 cals. ; it is hence very unstable and is readily decomposed by the 
detonation of a mercury fulminate cap or by an electric discharge, developing 
as much heat as an equal volume of hydrogen on conversion into water. The 
explosion takes place much more readily and is much more dangerous with 
the compressed gas and still more so with the liquid. 

Acetylene decomposes at 780 and, when mixed with air, ignites at 480. 
One cubic metre (1-165 kilo) of acetylene, in burning, develops 14,350 Cals. 
(12,300 Cals. per kilo), whilst ordinary coal-gas gives about 5000 Cals. 

When mixed with air or, better, with oxygen it forms a detonating mixture 
which explodes with great energy in contact with an ignited body. The 
explosion is violent even with 1 vol. of acetylene and 40 vols. of air ; it reaches 
its maximum violence with 1 vol. of the gas and 12 vols. of air (2-5 vols. of 
oxygen), whilst scarcely any explosion but mere burning takes place with 
1 vol. of acetylene and 1-3 vol. of air (as has been already stated on p. 33, 
ordinary illuminating gas only explodes when at least 1 vol. is present to 
about 20 vols. of air). 

Explosive mixtures of acetylene are more dangerous than those of coal-gas 



ACETYLENE 93 

owing to the greater speed of propagation of the explosion (e.g. with 1 vol. of 
acetylene and 40 of air), the explosive force being thus increased (see section 
on Explosives) ; further, acetylene contains less hydrogen and hence forms 
less water, the condensation of the gases resulting from the explosion being 
consequently smaller. The wide limits of the explosive mixtures (from 2-4 
to 130 vols. of acetylene per 100 vols. of air) are explained by the fact that this 
gas, being an endothermic compound, reacts or decomposes with great facility. 

In contact with copper, bronze, silver, &c., acetylene readily forms explosive 
acetylides (see p. 91). 1 

It was at first thought that acetylene, like carbon monoxide, was poisonous, 
but experiments made during the last few years have shown that animals do 
not die in an atmosphere containing 9 per cent, or, in some cases, even 20 per 
cent, of the gas. When, however, the acetylene is highly contaminated with 
sulphides and phosphides, it may be poisonous. 

With an ordinary gas-jet, acetylene burns with a reddish, smoky flame ; 
but by passing the gas at a pressure of 60 mm. through two jets nearly meeting 
at an angle, a white, highly luminous, fan-shaped flame is obtained without 
the dark middle portion of the ordinary bat's-wing coal-gas flame. 

One kilo of chemically pure calcium carbide should yield theoretically 349 litres of 
acetylene, and good commercial carbide yields practically 300 litres. The luminosity of 
acetylene in comparison with that of other substances has already been referred to on 
p. 57. A proportion of 2 vols. of air to 3 of acetylene gives the maximum luminosity, 
and at the present time special incandescent mantles are made for use with acetylene. 

The impurities present in ordinary acetylene (98-99 per cent, purity) are : N, NH 3 , 
CO, H 2 S and PH 3 , the last three of which are poisonous. The gas is purified by passing 
it through an acid solution of a metallic salt. 

Lunge and Cederkreutz recommend chloride of lime (hypochlorite) for purifying 
acetylene, care being taken that the mass does not heat, as this would be dangerous. 
Latterly it has been suggested to fix the PH 3 by passing the gas through concentrated 
sulphuric acid (64 Be.) saturated with As 2 3 . A good purifying material is made 
by preparing a paste of calcium hypochlorite, quicklime, sodium silicate and powdered 
calcium carbide, this remaining porous when allowed to dry in the air. 

The use of liquid acetylene would be very convenient, but is highly dangerous, since 
a sharp blow or other accident might easily produce a terrible explosion. 

It is still too expensive to employ in place of benzene for carburetting coal-gas. 
Dissolved in acetone, which dissolves a large quantity of it (vide supra), it is used to great 
advantage for the oxy-acetylene blowpipe in place of oxy-hydrogen. With the latter, for 
every cubic metre of oxygen 4 cu. metres of hydrogen are used practically (theoretically 
2 cu. metres), whilst the same amount of oxygen burns with 600 litres of acetylene 
(theoretically 400 litres), which costs much less than 4 cu. metres of hydrogen. The oxy- 
acetylene flame exhibits at the centre a shining point, which has a temperature of 
2800-3000, and to fuse iron sheets 1 mm. thick requires 50-75 litres of acetylene, while 
in an hour sheets 5 mm. in thickness can be melted. 

With a slight excess of oxygen large tubes are easily cut and steel blocks perforated. 

Acetylene dissolved in acetone, especially if the solution is absorbed by porous material, 
is not at all dangerous and can be transported in iron cylinders. 

The hope of manufacturing synthetic alcohol economically from acetylene has died 
out. Even for motors it is still too dear to use. Acetylene can, however, be used 
conveniently with a rational plant and relatively small gasometers connected with iron 
tubes which carry the gas direct to the burners (when prepared from pure carbide) ; but 
it is necessary to avoid the use of copper or bronze in any part of the gasometers, pipes 

1 The ready formation of metallic acetylides, especially that of copper, led Brdmann (1907) to devise a rapid 
and exact analytical method for the direct quantitative precipitation of copper from any solution and in presence 
of any metals (except Ag, Hg, Au, Pd, and Os, which must be previously eliminated) ; the feebly alkaline solution 
of the copper salt is reduced until decolorised with hydroxylamine hydrochloride, C 2 H 2 being then passed through 
and the precipitated copper acetylide collected on a filter, washed with water and pumped off ; together with 
the filter-paper it is introduced into a porcelain crucible, treated with 10 to 15 c.c. of dilute nitric acid <sp. gr. 1-15) 
and eight to ten drops of concentrated nitric acid (sp. gr. 1-52), dried on a water-bath, heated rapidly to redness 
and weighed as CuO. The acetylene used for this precipitation should be washed with lead acetate solution. 



94 ORGANIC CHEMISTRY 

and taps, in order to avoid explosions, which are almost always due to the formation of 
copper acetylide. 1 

In testing the purity of acetylene the only quantitative determination usually made 
is that of the hydrogen phosphide, which should not occur in greater proportion than 
1 grm. per cubic metre, since, besides being poisonous and having an unpleasant smell, it 
facilitates the formation of explosive metallic acetylides. (The estimation of the impurities 
in carbide is described in vol. i, p. 505.) 

III. HYDROCARBONS OF THE SERIES C,,H 2 ,,_ 4 and C,,H,,,. 6 

DI ACETYLENE, C 4 H 2 (Butandiine), CH i C-C : CH, is a gas and forms the usual 
metallic acetylides. 

DIPROPARGYL, C 6 H 6 (Hexan-1 : 5-diine), CH C.CH 2 -CH 2 -C i CH, is isomeric 
with benzene, boils at 85, and can take up 8 atoms of bromine. It is obtained from 
diallyl and readily forms metallic acetylides. 

HEXAN-3 : 4-DIINE, CH 3 'C i C-C C-CH 3 , is also isomeric with benzene. 



BB. HALOGEN DERIVATIVES OF THE HYDROCARBONS 

The Table on page 95 summarises the physical properties of the more 
important halogen derivatives of the hydrocarbons, the first column giving 
the hydrocarbon residue (alkyl) united with the halogen. 

I. HALOGEN DERIVATIVES OF SATURATED HYDROCARBONS 

PROPERTIES. Very few are gases, several are liquids and, those which 
contain many atoms in the molecule are solids. The iodo-compouiids 
boil at higher temperatures than the corresponding bromo- and chloro- 
compounds. They are very slightly, if at all, soluble in water, but are readily 
soluble in alcohol, ether, and glacial acetic acid. 

Most of them burn easily, and ethyl and methyl chlorides colour the edges 
of the flame green. Some of them, containing few carbon atoms, produce 
ancesthesia, e.g. CHC1 3 , CH 2 C1 2 , C 2 H 3 C1 3 , C 2 H 5 Br, C 2 H 5 C1. 

Generally they do not react with silver nitrate, since these compounds, 
in solution, are not dissociated and do not give free halogen ions (see vol. i. 
p. 91 et seq.). In alcoholic solution, ethyl iodide gives a little precipitate in 
the cold, and ethyl bromide in the hot, whilst the chloride gives no precipitate 
at all, with silver nitrate. 

The bromo- and iodo-compounds exhibit great reactivity and effect the 
most varied and interesting reactions and syntheses ; methyl iodide reacts 
the most readily of all, since the reactivity diminishes with increase of mole- 
cular weight. 

The halogens of these compounds can easily be replaced by H (by sodium- 
amalgam, or zinc dust and hydrochloric or acetic acid). 

These derivatives can, to some extent, be transformed one into the other, 
e.g. the chlorides into iodides by treatment with KI or CaI 2 , and the iodides 
into the fluorides (more volatile than the chlorides) by means of silver fluoride. 

1 The numerous types of apparatus for generating acetylene may be divided into three groups : 

(1) Those where the carbide and water are in separate vessels communicating by a tube furnished with a tap 
which automatically opens more or less and so diminishes or increases the supply of the gas. To prevent the 
carbide, or rather the lime formed, from holding water and generating gaseven after the tap is closed, the carbide 
is impregnated with an indifferent substance, e.g. paraffin, stearin, oil, sugar (to dissolve the lime as calcium 
saccharat e). &c. One inconvenience of this procedure is that at some places the carbide, in presence of little water, 
becomes excessively heated and may produce an explosion, which is dangerous if the gas is under pressure. 

(2) Those where the carbide is suspended at a certain part of the vessel containing the water ; acetylene is 
then generated when the level of the water rises to the carbide and ceases automatically when it falls. 

(3) Those where the carbide and water are separated, a small quantity of carbide being dropped into excess of 
water. This would be the most rational method, but is perhaps not the most convenient owing to the difficulty of 
powdering the carbide (often very hard) without allowing it to absorb moisture. 



HALOGEN DERIVATIVES 



95 



Alkyl 


Names of the Alkyls 
and Isomeridcs 


Chlorides 


Bromides 


Iodides 


B.-pt. 


Sp.gr. 


B.-pt. 


Sp.gr. 


B.-pt. 


Sp.gr. 




(a) SATURATED 
















DERIVATIVES 
















(1) MonositbgtUtUed 














CH, 


Methyl 


- 23-7 


0-952 (0) 


+ 4-5 


1-732 (0) 


+ 45 


2-293 (18) 


CjH 5 


Ethyl 


+ 12-2 


0-918 (0) 


38-4 


1-468 (13) 


+ 72-3' 


1-944 (14') 


C,H 7 


n-Propyl 


+ 46-5 


0-912 (0) 


71 


1-383 (0) 


102-5 


1-786 (0) 




Isopropyl 


36-5 


0-882 (0) 


60 


1-340 (0) 


89 


1-744 (0) 


CH, 


n-Butyl (primary) 


78 


0-907 (0) 


101 


1-305 (0) 


130 


1-643 (0) 




Isobutyl 


68-5 


0-895 (0) 


92 


1-204 (16) 


119 


1-640 (0) 




sec.-Butyl 














119-120 


1-626 (0) 




tert.-Butyl 


56 


0-866 (0) 


Tfl 


1-215 (20) 


100 


1-571 (0) 


C 5 H n 


n-Ainyl (primary) 


107" 


0-901 (0) 


129 


1-246 (0) 


156 


1-543 (0) 




Isoamyl, (CH,), CH- 


.101 


0-893 (0). 


121 


1-236 (0) 


148 


1-468 (0) 




CH,-CH,-X 
















tertiary-Butylmethyl 





0-879 (0) 





1-225 (0) 





1-050? (0) 




(CH,),C-CH,-X 
















active- Amyl 


97-99 


0-886 (15) 


118-120 


1-221 (20) 


148 


1-524 (20) 




(CH,)(C,H,)CH- CH,- X 














C.H,, 


n-Hexyl (primary) 


134 


0-892 (16) 


156 


1-193 (0) 


182 


1-461 (0) 




n-Hexyl (secondary) 








144 





168 


1-453 (0) 


C 7 H U 


n-Heptyl (primary) 


159 


0-881 (16) 


179 


1-113 (16) 


201 


1-386 (16) 


CH I7 


n-Octyl (primary) 


180 


0-880 (16) 


199 


1-116 (16) 


221 


1-345 (16) 




(2) Disubsttiuied 














>CH, 


Jlethylene, CH,X, 


42 





97 





180 





-CH 2 -CH 2 


Ethylene 


84 





131 











CH, CH 2 < 


Ethylidene (or ethydene) 


57 





108 













(3) Trisubstituted 
















CHX, (chloroform, 


61" 





161" 





solid 







bromoform, iodoform) 










mpt.H9 






CH.-CC1, methyl chloro- 


74 





188 













form (a-trichloroethane 
















CH.C1-CHC1, (/3-tri- 


114 





220 













chloroethane) 
















CH.X-CHX-CH,X (tri- 


168 



















chlorohydrin, tri- 
















bromohydrin) 
















(4) Polysvbftituted 
















CX 4 (carbon tetra- 


77 











solid 







chloride, iodide) 
















C a Cl, perchloroethane 


solid 





















m.pt. 187 














(&) UNSATURATED 
















DERIVATIVES 
















(1) Ethylenic series 














CH, :CH-X 


Vinyl chloride, &c. 


- 18 





23 





56 





C,H,-X 


AUyl 


46 





70 





101 





CVH,:X S 


Dichloroethylene 


55 

















G,H : X, 


Trichloroethylene 


88 

















C, : X 4 


Tetrachloroethylene 


121 


















(2) Acetylene tenet 














HC: CX 


Monochloro- and mono- 


gas 





gas 


_ 










bromo-acetylene 















METHODS OF PREPARATION, (a) By the action of halogens on 
saturated h3 r drocarbons : chlorine and bromine react directly at the ordinary 
temperature on the gaseous hydrocarbons, and on heating with the liquid ones. 

The first halogen atom is fixed more readily than the succeeding ones, 
and the addition of iodine facilitates the reaction with bromine and chlorine, 
since the iodine forms, for example, IC1 3 , which readily gives nascent chlorine, 
IC1 3 = IC1 + C1 2 (i.e. it acts like SbCl 5 , which yields SbCl 3 + Cl ? ). By 
saturating with chlorine and heating under pressure energetic chlorinations 
may be effected. 

Methane, ethane, propane, &c., exchange their hydrogen atoms one by 



96 ORGANIC CHEMISTRY 

one for chlorine atoms, the completely substituted compounds (C 2 C1 6 , C 3 C1 8 , &c., 
and especially the higher ones), on further energetic chlorination, being resolved 
into other completely chlorinated compounds containing less numbers of 
carbon atoms : C 2 C1 6 + C1 2 = 2CC1 4 ; C 3 C1 8 + C1 2 = C 2 C1 6 + CC1 4 , a little 
hexachlorobenzene, &c., being always formed as well. 

Iodine scarcely ever acts directly on the hydrocarbons, since the HI, 
formed acts in the opposite sense on the iodo-products. The reaction proceeds 
only in presence of iodic acid or mercuric oxide, which fixes the hydrioclic 
acid as it is formed. 

The iodo -compounds are easily obtained from zinc-alkyls and iodine. 

When the halogens act directly, the more energetic (F or Cl) replaces the 
weaker (Br or I). The iodo-compounds may, however, be easily obtained by 
preparing first the magnesium compounds of the alkyl chlorides or bromides 
and treating these with iodine : 

Alkyl-Mg-Cl + I 2 = Alkyl-I + MglCl. 

(b) Unsaturated hydrocarbons, with the halogen hydracids, give saturated 
monosubstituted derivatives : C 2 H 4 + HBr = C 2 H 5 Br, ethyl bromide, &c. ; 
if the halogens act directly, disubstituted saturated products are obtained : 
C 2 H 4 + C1 2 = C 2 H 4 C1 2 , ethylene dichloride. 

Propylene, CH 3 CH : CH 2 , reacts with HI giving isopropyl iodide, 
CH 3 -CHI-CH 3 , which is decomposed by alcoholic potash, yielding propylene ; 
but normal propyl iodide, CH 3 -CH 2 -CH 2 I, which also yields propylene when 
HI is removed from it, can thus be converted into isopropyl iodide. 

Similar behaviour is exhibited by the butyl iodides. 

The halogen always goes to the carbon atom united with the lesser number of 
hydrogen atoms : CH 3 -CH : CH 2 + HI = CH 3 -CHI-CH 3 . 

(c) The alcohols C w H 2w+1 OH with the halogen hydracids give : 
C w H 2n+1 OH + HBr = H 2 + CjjHg^+jBr, but the reverse action also pro- 
ceeds and to limit this, excess of the halogen hydracid is used and the water 
formed is fixed, e.g. by addition of zinc chloride. 

Further, the chlorine of the phosphorus chlorides also replaces hydroxyl : 
PC1 3 + 3C 2 H 5 OH = P(OH) 3 + 3C 2 HsCl, or, better, PC1 5 + C 2 H 5 OH = 
POC1 3 + HC1 + C 2 H 5 C1. This reaction is of importance for the preparation 
of the bromo- and iodo-compounds : 3CH 3 -OH + P + 31 = 3CH 3 I + H 3 P0 3 ; 
the bromine or iodine first acts on the phosphorus to form PBr 3 or PI 3 , this 
then reacting with the alcohol. 

The polyhydric alcohols act in the same way ; for example, glycerol, 
C 3 H 5 (OH) 3 reacts with PC1 5 giving trichlorohydrin, CH 2 C1 CHC1 CH 2 C1. 

The resulting halogenated products are easily separated by distillation, 
as the phosphoric acid does not distil. In these, as in most other chemical 
reactions, secondary products are always formed ; these are often very com- 
plex and form viscous resins of unknown composition. 

(d) The aldehydes and Tcetones yield disubstituted products : for example, 
ethylidene chloride, CH 3 -CHC1 2 , is obtained from acetaldehyde, CH 3 -CHO, 
and dichloropropane, CH 3 CC1 2 CH 3 , from acetone, CH 3 -CO-CH 3 , by the 
action of PC1 5 . 

METHYL CHLORIDE (Chloromethane), CH 3 C1. This is prepared by 
passing hydrogen chloride into boiling methyl alcohol containing half its 
weight of zinc chloride in solution, or by heating 1 part of methyl alcohol 
with 3 parts of concentrated sulphuric acid and 2 parts of concentrated hydro- 
chloric acid. Industrially it can be obtained by heating methyl alcohol and 
crude, concentrated hydrochloric acid together in an autoclave. 

It is also obtained to-day in appreciable quantity, by the old Vincent 
process, from the final residues of the beet-sugar industry, which are evaporated 



ALKYL HALOGEN COMPOUNDS 97 

and then dry-distilled. In this way an abundant quantity of trimethylamine 
is formed ; this is neutralised with HC1, and the hydrochloride distilled at 
300. A regular evolution of methyl chloride and trimethylamine is thus 
obtained : 3N(CH 3 ) 3 HC1 = 2CH 3 C1 + 2N(CH 3 ) 3 + CH 3 -NH 2 -HC1. 

Triinethylamine hydro- Trimethyl- Methylamine hydro- 

chloride amine chloride (residue) 

The chloromethane, distilled as a gas, is purified with HC1, dried with 
CaCl 2 , and liquefied in steel cylinders under pressure, just as is done with 
carbon dioxide (vol. i, p. 382). 

It is a colourless gas of ethereal odour, and at 23-7 becomes liquid, 
then having a sp. gr. 0-952 (at 0). Water dissolves one-fourth of its volume, 
and alcohol rather more. It burns with a green-edged flame. 

In the liquefied condition it is used as a local anaesthetic ; it is used also 
to extract perfumes from flowers, and in considerable quantities for the 
manufacture of dyestuffs (methyl green), especially for methylation ; but 
the greatest amount is employed in cooling machines. In France there are 
about 100 ice-machines which use methyl chloride instead of liquefied NH 3 , 
C0 2 , or S0 2 . In brass cylinders containing from 1 to 30 kilos it is sold at 
11s. to 14s. Qd. per kilo, in addition to the cost of the cylinder, which is 
20s. for the 1-kilo, 25s. Qd. for the 3-kilo, and 3 16s. for the 30-kilo size. 

METHYL IODIDE, CH 3 I, is prepared from methyl alcohol, phosphorus, and iodine 
as described later for ethyl iodide. It is a liquid of sp. gr. 2-293, boiling at 45 ; with 
excess of water at 100 it is decomposed into hydrogen iodide and methyl alcohol. 

ETHYL CHLORIDE (Chloroethane), C 2 H 5 C1, was termed by Basil Valentine " Spiritus 
salis et vini," or spirit of sweet wine. It is obtained from ethane and chlorine, or by passing 
hydrogen chloride into a solution of zinc chloride and ethyl alcohol. It is also formed as 
a secondary product in the manufacture of chloral. It boils at + 12-2 and burns with a 
flame having green edges. It is a local anaesthetic and is soluble in alcohol, but only slightly 
so in water. It costs from Is. Id. to 4s. per kilo in metal cylinders containing 1 to 30 kilos. 

ETHYL IODIDE, C 2 H 5 I, is prepared by digesting 10 grms. of red phosphorus with 80 
grms. of absolute alcohol for 12 hour's and gradually adding 100 grms. of iodine ; the mix- 
ture is then heated for 2 hours under a reflux condenser and the ethyl iodide distilled on 
the water-bath, washed with dilute alkali and with water, and dried by means of calcium 
chloride. According to Ger. Pat. 175,209, ethyl iodide is obtained quantitatively if 
diethyl sulphate is slowly added to the calculated amount of hot potassium iodide solution. 
It boils at 72-3 and has the sp. gr. 1-944 (at 14) ; it is highly refractive and dissolves in 
alcohol or ether. It decomposes when heated with water at 100. Chlorine converts it 
into ethyl chloride and bromine into ethyl bromide. In the light it slowly decomposes 
with separation of iodine, which colours the liquid brown, but it remains colourless in 
presence of a drop of mercury. It is used as an inhalation for the treatment of asthma. 
It costs about 28s. to 32s. per kilo. 

ETHYL FLUORIDE, C 2 H 5 F, is liquid at -48, burns with a blue flame, and does not 
attack glass. 

From PROPANE two series of isomeric compounds are derived: CH 3 CH 2 CH 2 X, 
prepared from normal propyl alcohol, and CH 2 -CHX-CH 3 , derived from isopropyl alcohol, 
and hence from acetone. 

ISOPROPYL IODIDE (Iodo-2-propane), CH 3 -CHI.CH 3 , is obtained from glycerol, 
phosphorus and iodine, small amounts of allyl iodide and propylene being also formed. 

The butyl compounds occur in four isomeric modifications : 

NORMAL BUTYL IODIDE (Iodo-i-butane), CH 3 - CH 2 - CH 2 - CH 2 I. 

SECONDARY BUTYL IODIDE (Iodo-2-butane), CH 3 . CH 2 - CHI - CH 3 . 

ISOBUTYL IODIDE (Methyl-2-iodo-3-propane), ^ 3 >CH-CHI. 

/-ITT 

TERTIARY BUTYL IODIDE (Methyl-2-iodo-2-propane), CH 3 >CI-CH 3 . 

The constitutions of the four isomerides are deduced from those of the corresponding 
butyl alcohols from which they are obtained by the action of hydriodic acid. 
Of the AMYL derivatives eight isomerides are known. 

ii 7 



98 ORGANIC CHEMISTRY 

METHYLENE CHLORIDE (Dichloromethane), CH 2 C1 2 , bromide and iodide (see 
Table, p. 95). 

ETHYLENE COMPOUNDS, CH 2 X-CH 2 X, are formed from ethylene by the addition 
of halogens or from glycol, C 2 H 4 (OH) 2 and halogen hydracids. 

ETHYLIDENE (or Ethydene)COMPOUNDS, CH 3 CHX 2 , are obtained by substituting 
the oxygen of the aldehydes by halogens. 

ETHYLENE CHLORIDE (Dichloro-i : 2-ethane), CH 2 C1-CH 2 C1 (Dutch liquid), boils 
at 84. The IODIDE, BROMIDE, and CHLORIDE with alcoholic potaeh give acetylene 
and glycol. 

ETHYLIDENE CHLORIDE (Ethydene chloride or Dichloro-i : i -ethane), 
CH 3 .CHC1 2 , is obtained from aldehyde and phosgene: CH 3 -CHO + COCJ 2 = C0 2 + 
CH 3 -CHC1 2 , chloral (which see) being also formed ; it boils at 57. 

CHLOROFORM (Trichloromethane), CHC1 3 . Chloroform was discovered 
by Liebig and Souberain and its constitution shown by Liebig in 1835. 

It is prepared from (1) ethyl alcohol or (2) acetone, by heating with chloride 
of lime and water : (1) 4C 2 H 6 OH + 16CaOCl 2 = 3H 2 C a 4 Ca (calcium 
formate) + 13CaCl 2 + 8H 2 + 2CHC1 3 ; in this reaction there is always an 
appreciable evolution of C0 2 , which appears to originate in the oxidation 
of the alcohol, and liberates HC10 and so forms aldehyde and hence chloral, 
this, in presence of lime, yielding chloroform : 3C 2 H 5 OH + 8Ca(OCl) 2 = 
2CHC1 3 + 3CaC0 3 + C0 2 + 8H 2 + 5CaCl 2 . 

(2) 2CH 3 -CO-CH 3 + 3Ca(OCl) 2 = 2CH 3 -CO-CC1 3 (trichloro-acetone) 
+ 3Ca(OH) 3 ; 2CH 3 -CO-CC1 3 + Ca(OH) 2 = Ca(C 2 H 3 O 2 ) 2 (calcium acetate) 
+ 2CHC1 3 . 

In a very pure form for pharmaceutical use it is obtained by treating 
chloral with aqueous caustic soda solution, sodium formate being also formed : 

/ H 
CC1 3 C( + NaOH = CHC1 3 + H C0 2 Na. 

% 

Chloroform can also be obtained industrially by reducing carbon tetra- 
chloride with hydrogen in the hot : CC1 4 + H 2 = HC1 + CHC1 3 ; the hydrogen 
necessary to treat 75 kilos of CC1 4 is given by 60 kilos of HC1 at 22 Baume 
and 50 kilos of zinc. 

To obtain very pure chloroform from the impure product, Anschtitz treats 
the latter with salicylic anhydride, C 6 H 4 C0 2 , which forms a crystalline mass 
only with chloroform, (C 6 H 4 C0 2 ) 4 , 2CHC1 3 ; this, after separation from the 
mother-liquor, is heated on the water-bath, when pure chloroform distils off. 

It is a colourless liquid with a sweet ethereal smell and taste ; it dissolves 
only to a slight extent in water (0-7 per cent.), but is soluble in alcohol or 
ether. It boils at 61-2, and its vapour pressure at 20 is 160 mm. of mercury ; 
its specific gravity is 1-5263 at and 1-500 at 15, referred to water at 4. 

It is non-inflammable, and it dissolves resins, rubber, fats, and iodine, 
with the last of which it gives violet solutions. 

Exposed to light and air, it decomposes partially into Cl, HC1, and COC1 2 , 
but it can be kept in yellow bottles, while that for pharmaceutical use keeps 
better if 1 per cent, of absolute alcohol is added. 

It is the most efficacious anesthetic (Simpson, 1848), but in some cases 
may cause death if not used with great care, since it acts on the heart ; to 
diminish this effect, it is mixed with atropine or morphine. 1 

1 From coal-tar products various anaesthetics or hypnotics are produced synthetically, and these have been 
of great service to medicine, especially to surgery, rendering possible the execution of the most complicated opera- 
tions without any pain to the patient. At first substances were used which produced general ancesthesia of the 
organism, but they were accompanied by many inconveniences, sometimes by fatal results. 

Indeed, the anaesthetic is transported by the blood into contact with the higher nervous centres by which 
pain is felt, producing poisoning and paralysis of them often lasting for some time ; at the same time an influence 
is felt by the centres controlling the action of the heart and of respiration, this being the cause of the danger and 
disturbance produced by general anaesthesia. The nerve-currents start from the periphery, from the points where 
the surgical operation is to begin, and are transmitted to the brain, which transforms them into painful sensations, 



MANUFACTURE OF CHLOROFORM 93 

In America, chloroform is used to render pigs insensible so as to kill them 
painlessly and to skin them more easily. Also, in fattening them, they are 
subjected to periodic inhalations of chloroform, which renders them more 
restful. 

Chromic acid transforms chloroform into phosgene (COC1 2 ), whilst potassium 
amalgam gives acetylene. With potassium hydroxide, it gives potassium 
formate and chloride : 



CHC1 



H-C0 2 K 



2H 2 0. 




FIG. 102. 



3 4KOH = 3KC1 
With ammonia at a red heat, it gives hydrocyanic and hydrochloric acids : 
CHC1 3 + NH 3 = HCN + 3HC1. 

Pictet Chloroform is pure chloroform obtained from the commercial 
product by freezing it at -80 to -120 ; the impurities remain in the 
liquid, the crystals giving pure chloro- 
form. 

INDUSTRIAL PREPARATION. A 

considerable amount of chloroform is pre- 

pared even to-day from chloride of lime 

and alcohol, but the latter should not 

contain fusel oil. The reaction takes place 

in a double -bottomed iron boiler, A (Fig. 

102), which contains a mechanical stirrer, 

M, and into which the chloride of lime, 

water, and alcohol are introduced through 

a large aperture, F, at the top. The heat- 

ing is effected by a steam-coil, Pp, and 

cold water can be circulated through the 

jacketed bottom, when necessary, by 

means of another pipe not shown in the 

figure. To produce 100 kilos of chloro- 

form 100 kilos of alcohol and 1300 kilos 

of chloride of lime (with 36 per cent. Cl) 

are actually used ; but in practice a large excess of alcohol about ten times that really 

required by the reaction is employed, but the excess is used up, since it is added all at 

once and the process then continued by gradually replacing the quantity that reacts. 

An apparatus for producing 125 kilos of chloroform daily with four charges of the 
apparatus in 24 hours is charged first of all with 300 kilos of alcohol (96 per cent.) and 
1300 litres of water, 400 kilos of chloride of lime being then added, in small quantities and 
with constant stirring ; the aperture F is then covered and the temperature raised to 
40 by steam -heating. The steam is then shut off and the stirring continued until the 
temperature rises spontaneously to 60 (if this is exceeded, cold water is passed through 
the jacket). The mixing is then stopped and the chloroform, mixed with a little alcohol, 
begins to distil. The vapours are cooled and condensed in a coil, Z, placed in the lank, K, 
through which cold water circulates from V to ms. The mixed chloroform and alcohol 
is collected in a reservoir, L, with a graduated standpipe. When about 30 kilos of 
chloroform have distilled over, the stirrer is started again, and a little of the distillate 

and it is by influencing the cerebral centres by anaesthetics that pain is avoided ; but anaesthesia ceases to be 
dangerous if the peripheral nervous centres at the beginning of the nerve-currents are paralysed without the latter 
reaching the brain. Thus local anaesthesia is much more rational and less dangerous, since the insensibility extends 
only to one organ or one region of the subject of the .operation. 

So that, to chloroform, ether, &c., was added, in 1885, cocaine, which paralyses only the sensitive peripheral 
nerves without influencing the motor nerves. By studying anaesthetic and hypnotic substances chemists were 
able to determine what specific atomic groups produced anaesthetic properties in a molecule. Thus, with many 
of these substances, it was found to be the hydroxyl group which induced sleep, especially when it is united to 
carbon joined at the same time to several alkyl groups ; replacement of the hydroxyl by other groups resulted in 
the disappearance of the anaesthetic properties. Also various amino-acid gioups, under certain definite condi- 
tions, give rise to anaesthetics. To enumerate all the members of the vast group of anaesthetics which chemistry 
has placed at the disposal of surgery would be out of place here, but the following few examples may be mentioned : 
a-eucaine, ^-eucaint, orthoform, alipine, holocaine, and, on the other band, ttUphonal, trional, dormiol, hedonal, 
Veronal, &c. Other properties of anaesthetics are described in Part III, in the section on alkaloids. 



100 

collected from time to time from the tap, y, at the bottom of the condensing coil ; when 
the addition of water to this no longer causes separation of chloroform at the bottom of 
the liquid, the remainder of the distillate obtained finally the contents of the boiler 
are again heated with steam is collected at y, communication with the reservoir, L, 
being shut off and the tap, O, closed. More or less dilute alcohol now distils over 
and the distillation is stopped when the distillate contains less than 2 to 2ij per cent, of 
alcohol. 

The total amount of alcohol (usually 260-265 kilos) in the alcoholic distillate (500-600 
litres) is determined, and sufficient pure alcohol added to bring the total quantity up to 
300 kilos ; this dilute solution serves for the next operation, allowance being made for 
the water it contains. In this way the loss of alcohol is small. 

The crude chloroform is washed and agitated with water (30 litres per 100 kilos) to 
remove the alcohol present, or, better, with lime-water or a weak soda solution, which 
removes also the small quantity of HC1 that always forms. Finally, the liquid is agitated 
with concentrated sulphuric acid, thoroughly rewa?hed with water, dried over CaCl 2 and 
redistilled, the chloroform, passing over at 62-63, being collected. Instead of alcohol, 
acetone is used by some manufacturers when it can be bought cheaply, and in that 
case 100 kilos of acetone yields up to 170 kilos of chloroform. According to Ger. Pat. 
129,237, a good yield and continuous formation of chloroform are obtained by heating, in 
a vessel divided into a number of cells communicating at the bottom, alcohol (35 Be.) 
which has been previously chlorinated by means of chloride of lime and alkali in the hot. 

During recent years the industrial preparation of chloroform has again been attempted 
by electrolysing an aqueous solution of KC1 (20 per cent.) into which alcohol or acetone 
is slowly introduced. In this process 1 h.p.-hour is consumed to produce 40 grms. of 
chloroform. 

Erlworthy and Lange (Fr, Pat. 354,291, 1905) propose to produce chloroform from 
methane and chlorine diluted with indifferent gases (N, C0 2 ) by subjecting the mixture 
to the action of light in suitable retorts : CH 4 + 6C1 = 3HC1 + CHC1 3 . 

TESTS FOR CHLOROFORM. Minute quantities of chloroform can be detected 
by gently heating a little of the liquid with a few drops of aniline and of alcoholic potash 
solution, the characteristic repulsive odour of phenylcarbylamine (phenyl isocyanide) 
being formed. Pure chloroform for medicinal use should not be acid or give a precipitate 
with silver nitrate solution or redden potassium iodide solution ; on evaporation it should 
not leave a residue of water or odorous substances, and it should not darken with 
concentrated sulphuric acid. To test for the presence in it of carbon tetrachloride, 20 c.c. 
are treated with a solution of 3 drops of aniline in 5 c.c. of benzene ; a turbidity or separa- 
tion of crystals of phenylurea indicates with certainty the presence of the tetrachloride. 
To ascertain if it contains alcohol it is treated with a very dilute potassium permanganate 
solution, which is decolorised in presence of this impurity. 

Its estimation is effected by treating a given weight with Fehling's solution (see under 
Sugar Analysis) and heating the mixture in a closed bottle on a water-bath for some hours 
(until the odour of chloroform disappears) ; the cuprous oxide, formed according to the 
equation CHC1 3 + 2CuO + 5KOH = K 2 CO 3 + 3H 2 O + 3KC1 + Cu 2 O, being weighed. One 
molecule of chloroform corresponds with 2 atoms of copper. 

It can also be determined by heating with alcoholic potash in a reflux apparatus on 
the water-bath ; it is then diluted with water, the alcohol distilled off, and the potassium 
chloride formed (together with potassium formate, see preceding page) titrated with a 
standard silver nitrate solution. This method serves for the estimation of all alkyl-halogen 
compounds. 

The price of industrial chloroform is about 8 per 100 kilos ; redistilled costs 2s. Wd. 
per kilo ; the pharmacopceial preparation 2s. 2d. ; puriss. from chloral, 6s. 5d. to 9s. Id. ; 
Pictet's, 12s. per kilo, and that of Anschiitz Wd. per 50 grms. Part of the chloroform 
consumed in Italy is imported from abroad ; in 1906 this amounted to 12,200 kilos ; in 
1907, 10,100 ; in 1908, 7000 ; and in 1909, 9000 kilos -of the value 680. 

IODOFORM (Tri-iodomethane), CHI 3 , was discovered by Serullas in 1822, 
and its constitution was established by Dumas who, unlike his predecessors, 
did not overlook the very small proportion of hydrogen (0-25 per cent.) 
present. 



IODOFORM 



It is formed by heating ethyl alcohol or acetone with iodine and sufficient 
alkali hydroxide or carbonate to decolorise the iodine (Lieberis reaction) : 

C 2 H 5 OH + 81 + 6KOH = CHI 3 + H-COOK + 5KI + 5H 2 0. 

This reaction (separation of yellow crystals and formation of a character- 
istic odour) is so sensitive that it serves for the detection of minute traces 
(1 : 2000) of ethyl alcohol or acetone in other liquids (waiting 12 hours 
for the separation of crystals if the amount of alcohol is small) ; the same 
reaction is, however, given by isopropyl alcohol, acetaldehyde (and by almost 
all compounds containing the group CH 3 -CO-), but not by methyl alcohol, 
ether, or acetic acid. 

For the practical preparation of iodoform 32 parts of K 2 CO 3 are dissolved in 80 parts 
of water and 16 parts of alcohol, the mixture being heated to 70 and 32 parts of iodine 
gradually added. The separated iodoform is filtered off and the iodine of the potassium 
iodide in the nitrate utilised as follows : 20 parts of HC1 are added and 2-3 parts of 
potassium dichromate, the liquid being then neutralised with K 2 CO 3 , mixed with a further 
32 parts of K 2 CO 3 , 16 parts of alcohol and 6 parts of iodine. On heating, a second quantity 
of iodoform separates, and after this or another similar operation the mother -liquor is 
treated to recover the iodine from the potassium iodide. 

It has been proposed to prepare iodoform by treating the metallic acetylides (see 
p. 91 ) with iodine and caustic soda. 

It seems that practical use is now made of the old electrolytic process, using a bath 
of 6 parts KI, 2 parts soda, 8 vols. alcohol, and 40 of water at 60-65. The iodine to be 
used in the reaction is set free at the anode and to avoid the formation of a little iodate 
with the KOH formed at the cathode the latter is enclosed in parchment paper. 

When pure, iodoform crystallises in hexagonal, yellow plates (sp. gr. 2), 
insoluble in water but soluble in alcohol or ether. It has a penetrating and 
persistent odour, ' recalling partly that of saffron and partly that of phenol. 
It melts at 119, readily sublimes, and is volatile in steam. On heating with 
either alcohol or reducing agents, it gives methyleiie iodide. 

It is used in surgery as an important antiseptic, which, however, acts 
indirectly on bacteria by means of the decomposition products formed from 
it under the action of the pus of wounds or of the heat of the body. 

Owing to its disagreeable odour, it has been to some extent replaced latterly 
by Xeroform, which is a tribromophenoxide of bismuth, C 6 H 2 Br 3 OH, Bi 2 2 , 
obtained by the action of bismuth chloride on sodium tribromophenoxide and 
forming a tasteless, odourless, yellow powder insoluble in water or alcohol ; 
it is used also as a disinfectant for the intestines, and costs 44s. to 48s. per 
kilo, whilst iodoform costs only 24s. to 28s. a kilo. 

TESTS FOR IODOFORM. It should leave no residue on sublimation and should 
dissolve completely in alcohol or ether. It is estimated by heating about 1 grm. with 
about 2 grms. of silver nitrate and 25 c.c. of concentrated nitric acid (free from chlorine) 
in a reflux apparatus so that the liquid does not boil ; when the nitrous vapours have 
disappeared the liquid is diluted with water to 150 c.c. and heated, the silver iodide being 
collected on a tared filter, dried and weighed : 1-789 grm. Agl corresponds with 1 grm. 
iodoform. 

CARBON TETRACHLORIDE (Tetrachloromethane), CC1 4 (see vol. i, p. 378). 

POLYCHLORO-DERIVATIVES OF ETHYLENE AND ETHANE. 1 Asymm. 
HEPTACHLOROPROPANE was prepared in 1910 by Boeseken and Prins from tetra- 
chloroethylene and chloroform in presence of aluminium chloride as catalyst. 

1 Since 1908 (Ger. Pats. 196,324, 204,516, 204,883, &c.), the Chemische Fabrik Griesheim-Elektron of Frankfort, 
and the Usines electriques de la Lonia of Geneva have placed on the market, as non-inflammable solvents for 
industrial purposes, six chlorinated compounds obtained as colourless liquids by the action of chlorine on acetylene. 
They are all good solvents for fats, resins, rubber, &c., and can replace advantageously benzene, carbon disulphide, 
and alcohol, since they are not inflammable and their vapours do not form explosive mixtures with air ; ovci 



; 102 



r.$>Jf.GANIC CHEMISTRY 

1 *f ' C r " 



II. HALOGENATED DERIVATIVES OF UNSATURATED 
HYDROCARBONS 

These are obtained from saturated halogen derivatives by partial elimination of the 
halogen hydracid : C 2 H 4 Br 2 = HBr + C 2 H 3 Br. They are formed by incomplete satura- 
tion, with halogens or halogen hydracids, of the less saturated hydrocarbons : 
C 2 H 2 + HBr = C 2 H 3 Br (see Table in footnote). 

The allyl compounds, C 3 H 5 X, are formed from allyl alcohol by the action of halogen 
hydracid or of phosphorus and halogen. 

ALLYL CHLORIDE (Chloro-3-propene-i), CH 2 : CH.CH 2 C1, the bromide and iodide 
having analogous constitutions. 

They are related to the natural allyl compounds (garlic oil and mustard oil). Two 
stereoisomerides are known : 

H C Cl H C Cl 

a-chloropropylene, and iso-a-chloropropylene, 

H C CH a CH 3 C H 



CC. ALCOHOLS 

These form an important group of organic compounds containing one or 
more characteristic hydroxyls, the hydrogen of which has pronounced reactive 
properties, so that numerous series of other compounds are derived from the 
alcohols. They have a neutral reaction, although their chemical behaviour 
is analogous to that of the inorganic bases which always contain the anion 
OH'. The majority of these alcohols are colourless liquids, but those of 
high molecular weights are oily, solid, and sometimes of a yellowish colour. 
The first members of the series are soluble in water, but with increase of 
molecular weight the solubility decreases and the smell, generally slight, also 
tends to disappear. They are often found in nature either free or combined 
with organic acids, in the fats, waxes, fruits, essential oils, &c. 

According to the number of hydroxyl groups they contain, they are divided 
into mono-, di-, . . . polyhydric alcohols, and may belong either to the satu- 
rated or to the unsaturated series already studied in connection with the 
hydrocarbons of which they retain the fundamental characters ; added to 
the latter are those characteristic of the alcoholic group, which we shall study 
generally with the monohydric alcohols. 

carbon tetrachloride they have the advantage of not attacking the metal parts of the extraction apparatus, and the 
loss on extraction varies from 0-3 to 0-8 per cent. ; they are, however, dearer than the ordinary solvents and seem 
to be injurious to health. The properties of these compounds are given in the following Table : 





DlCHLORO- 


TRICHLORO- 


TETRA- 


TETRA- 


PENTA- 


HEXA- 




ETHYLENE 


ETHYLENE 


CHLORO- 


CHLORO- 


CHLORO- 


CHIORO- 








ETHYLENE 


ETHANE 


ETHANE 


ETHANE 




C,H 2 C1, 


CjHCl, 


C 2 C1 4 


CjH^Cli 


CjHCl 6 


C 2 C1. 


Common name 


Didine 


Trieline 


EtUine 


Tetraline 


Pentaline 





Specific gravity . 


1-278 


1-471 


1-628 


1-600 


1-685 


2 


Boiling-point 


52 


85 


119 


144* 


159 


(185') 


Vapour pressure at 20 


205 mm. 


56 


17 


11 


7 


3 


Specific heat at 18 


0-270 


0-233 


0-208 


0-227 


0-207 


. 


Heat of evaporation 


41 cals. 


57-8 


50 


52-8 


45 





Freesing-point 





-70 





30 








Uses and properties 


Readily dis- 


Dissolves 


Serves well 


Dissolves 


Readily dis- 


Has an 




solves rub- 


fats, paraf- 


for remov- 


resins and 


solves cellu- 


odour like 




ber 


fin, and va- 


ing spots 


varnishes, 


lose acetate 


camphor, 






seline hotter 




like turpen- 


for artificial 


and serves 






than ben- 


tine and al- 


silk and 


as an insec- 






'ne 


cohol and dissolves cellu- 


cinemato- 


ticide 








lose acetate for films and 


graph films 










artificial silk 







MONOHYDRIC ALCOHOLS 103 

I. SATURATED MONOHYDRIC ALCOHOLS 

The specific gravity of these is always lower than that of water and up to 
the C 16 member they distil unchanged at the ordinary pressure ; beyond that 
reduced pressure must be employed. 

That alcohols always contain a hydroxyl group OH can be shown by the following 
chemical reactions : 

The alcohols can be obtained by the action of silver hydroxide, AG-OH (which cer- 
tainly contains the group OH), or even of the alkalis or hot water, on halogenated hydro- 
carbons : C w H 2n+1 I + AgOH = Agl + C re H 2w+1 OH. 

With the halogen hydracids the hydroxyl separates from the alcohols in the form of 
water : C re H 2n+1 OH + HBr = H 2 + C n H 2w+1 Br ; and the same happens with oxy- 
acids, the so-called esters being formed : C n H 2w+1 OH + HN0 3 = H 2 + C n H 2n+1 NO 3 . 
Just as sodium and potassium react with water, liberating hydrogen, so do they act 
on the alcohols, from which only the typical hydrogen (hydroxylic), not united directly 
to carbon, is eliminated : C n H 2n+1 OH + Na = C n H 2n+1 ONa (sodium alkoxide) + H. 
Magnesium alkoxides are also easily obtained. With phosphorus trichloride, however, 
the hydroxyl group is eliminated : 

3C n H 2n+1 OH + PC1 3 = 3C n H 2n+1 Cl = P(OH) 8 . 

On p. 16 the difference in constitution between ethyl alcohol and methyl ether has 
been demonstrated. 

If the hydroxyl group occurs in place of a hydrogen atom in the methyl group 
( CH 3 ) at the extremity of the hydrocarbon chain, the primary alcohols are obtained, 

/ ^ z \ 

all containing the characteristic group CH 2 -OH (i.e. Cf 1, e.g. propyl alcohol, 

CH 3 CH 2 CH 2 OH, and by oxidation of these alcohols are formed first aldehydes with 
the characteristic group ( X G'f ), and then acids with the characteristic carboxyl 



group COOH (i.e. Cf ). Substitution of a hydroxyl for a hydrogen atom in an 



intermediate methylene group ( = CH 2 )ln the saturated hydrocarbon chain yields secondary 
alcohols, which have the characteristic group ^>CH-OH (i.e. ^>C<^QTT) and on oxidation 

give ketones containing the special group ^>CO. Finally the substitution of the hydrogen 
of a branched hydrocarbon may take place in the methinic group (=CH), giving tertiary 
alcohols with the characteristic grouping =C-OH, the other three valencies of the carbon 
being united to three carbon atoms. When the secondary alcohols are oxidised they 
cannot give either acids or ketones with an equal number of carbon atoms, but, if the 
oxidation is energetic, the chain breaks, and then acids and ketones may be formed, but 
with less numbers of carbon atoms. 

According to B. Neave (1909), primary, secondary, and tertiary alcohols 
can be distinguished by the Sabatier and Senderens reaction (see p. 34), by 
passing the vapours of the alcohol over finely divided copper heated at 300 ; 
the primary alcohols form hydrogen and aldehydes (recognisable by Schiff s 
reaction ; see section on Aldehydes), the secondary ones give hydrogen and 
ketones (detectable by semicarbazide hydrochloride solution) and the tertiary 
alcohols give water and unsaturated hydrocarbons (which decolorise bromine 
water). 

The primary alcohols and the corresponding ethers have the highest boiling- 
points, the tertiary ones and, in general, those with branched chains showing 
the lowest boiling-points. 

In the group of alcohols the isomerism and the number of isomerides are 



104 O R GA N.I C CHEMISTRY 

similar to those of the halogenated derivatives of the hydrocarbons, since the 
halogen atom is here replaced by a hydroxyl group. * 

The names of the primary alcohols are made from those of the corresponding hydro- 
carbons (see p. 31) with the termination ol, and those of the secondary and tertiary 
alcohols are derived from the names of the hydrocarbons with the longest non-branched 
chains ; or the secondary and tertiary alcohols may be regarded as derivatives of methyl 
alcohol or carbinol, CH 3 OH, formed by substitution of the hydrogen atoms of the methyl 
group. We have, hence, two different, but still equally clear, systems of nomenclature. 
For example : 

(1) Normal butyl alcohol: CH 3 CH 2 CH 2 CH 2 OH = butan-1-ol or n-propylcarbinol. 

2 1 

(2) Secondary butyl alcohol: CH 3 .CH 2 -CH(OH).CH 3 = butan-2-ol or methylethyl- 
carbinol. 2 l 

123 

(3) Isobutyl alcohol: CH 3 CH CH 2 OH = 2-methylpropan-3-ol or isopropylcarbinol. 



CH, 



1 23 

(4) Tertiary butyl alcohol : CH 3 C CH 3 = 2-methylpropan-2-ol or trimethylcarbinol. 



CH 3 OH 

PROCESSES OF FORMATION OF MONOHYDRIC ALCOHOLS. As 

well as from the halogen derivatives, the alcohols can usually be obtained by 
decomposing esters with acids, alkalis, or superheated water. This reaction 
is termed saponification or hydrolysis : 

C 2 H 5 0-N0 2 + KOH - KN0 3 + C 2 H 5 -OH. 

Tn a general way, the primary alcohols are formed by reducing the acids 
(C n H 2n 2 ) or aldehydes (C n H ow O) with nascent hydrogen : 

7 
CH 3 CC (acetaldehyde) + 2H = CH 3 CH 2 OH. 

H 

Since the acids, in their turn, can be prepared from the alcohols with one 
carbon atom less, we have at our disposal a general reaction for preparing 
synthetically any higher alcohol. 

The secondary alcohols are formed by reducing the ketones,'C w H 2W 0, e.g. : 

CH 3 CO CH 3 + H 2 = CH 3 CH(OH) CH 3 

Acetone Isopropyl alcohol 

(see later, Aldehydes and Ketones). 

The tertiary alcohols are formed by the prolonged action of zinc methyl 
on acid chlorides, the intermediate compounds thus formed being decomposed 
with water. 

For the secondary and tertiary alcohols Grignard's reaction may also be 
employed (see later, Alkylmetallic Compounds). 

Of more industrial importance, however, is the preparation of some of the 
more common of these alcohols by the distillation of wood or the fermentation 
of certain carbohydrates (see later). 

In addition to the properties of the alcohols given above, namely, their 
behaviour towards acjds, halogens (which oxidise them), chlorides, and oxidising 
agents in general (which give aldehydes and acids), it may be mentioned that 
the higher alcohols (primary) are transformed into the corresponding acids 
by simple heating with soda lime. Traces of primary alcohols are detectable 
by oxidising with permanganate and sulphuric acid and then testing for 
aldehyde with a sulphurous acid solution of fuchsine. 



CONST ANTS OF ALCOHOLS 105 

ft 

PHYSICAL CONSTANTS OF THE MONOHYDRIC ALCOHOLS 



Name and Formula 


Specific 
gravity 


Melting- 
point 


Boiling- 
point 


1. Methyl alcohol, CH 3 -OH 


0-812 (0) 


-94, -98 


66 


2. Ethyl alcohol, C 2 H 6 -OH 


0-806 


-112 -117 


78 


3a. Normal propyl alcohol (prim.) 








CH 3 -CH 2 -CH 2 -OH 


0-817 


-127 


97 


36. Iso propyl alcohol (sec.) 








CH 3 -CH(OH)-CH 3 


0-789 (20) 





81 


4a. Normal butyl alcohol (prim.), C 4 H 9 -OH . 


0-810 


-80(-122) 


117 


46. Normal butyl alcohol (sec.), C 4 H 9 -OH 


0-808 





100 


4c. Isobutyl alcohol, C 4 H 9 - OH . . ; : . 


0-806 (20) 





107 


4:d. Tertiary butyl alcohol (trimethylcarbinol), 








C 4 H 9 -OH 


0-786 (20) 


+ 25 


83 


5a. Normal amyl alcohol (prim.) 








CH 3 -[CH 2 ] 3 -CH 2 -OH 


0-817 (20) 





138 


56. Amyl alcohol of fermentation or isobutyl- 








carbinol, (CH 3 ) 2 CH-CH 2 -CH 2 -OH . 


0-810 (20) 





130 


5c. Active amyl alcohol or sec. butylcarbinol, 








CH 3 -CH(C 2 H 5 )-CH 2 -OH 


0-816 (20) 





128 


5d. Trimethyl- or tertiary butyl-carbinol, 








(CH 3 ) 3 C-CH 2 -OH 


0-812 (20) 


49 


113 


5e. Diethylcarbinol, C 2 H 5 -CH(OH)-C 2 H 5 


0-831 (0) 





117 


5/. Methylpropylcarbinol, 








CH 3 .[CH 2 ] 2 -CH(OH)-CH 3 


0-824 (0) 





119 


5g. Methylisopropylcarbinol, 








(CH 3 ) 2 CH-CH(OH)-CH 3 


0-819 (0) 





112-5 


&h. Dimethylethylcarbinol, 








(CH 3 ) 2 C(OH).C 2 H 5 


0-814 (15) 


-12 


102 


6. Normal hexyl alcohol (prim.), C 6 H 13 -OH . 


0-833 (0) 





157 


7. Normal heptyl alcohol (prim.), C 7 H 15 -OH 


0-836 





175 


8. Normal octyl alcohol (prim.), C 8 H 17 -OH 


0-839 





191 


9. Normal nonyl alcohol, C 9 H 19 -OH 


0-842 


5 


213 


10. Decyl alcohol, C^^-OH . . . 


0-839 


+ 7 


231 


11. Undecyl CuH 28 -OH . , . . 





+ 19 


131(15rrm.) 


12. Dodecyl C^H^-OH . . 


0-831 


24 


143 


13. Tridecyl C^H^-OH . . . 





30-5 


156 


14. Tetradecyl alcohol, Ci 4 H 29 - OH 


0-824 


38 


167 


15. Pentadecyl alcohol, C^H^-OH 





45-46 





16. Hexadecyl (cetyl) alcohol, C 16 H 33 -OH 


0-818 


50 


190 


17. Octodecyl alcohol, C^H^-OH . 


0-813 


59 


211 


18. Ceryl C 26 H 53 -OH . . . 





79 





19. Myricyl C 30 H 61 -OH . 





85 






corre- 



By the behaviour of the nitro-compounds (prepared from the 
spending iodides and silver nitrite) and also by the initial velocity and degree 
of esterification, primary alcohols can be differentiated from the secondary 
and tertiary ones. 

Various primary normal alcohols enter inorganic compounds as alcohol of 
crystallisation, e.g. BaO, 2CH 3 -OH; CaCl 2 , 4CH 3 -OH; KOH, 2C 2 H 5 -OH 



MgCl 2 



6C 2 H 5 



OH ; CaCL, 4C,H 5 -OH, &c. ; it is hence evident why calcium 



chloride cannot be used for drying alcohol, although it serves well in the case 
of ether. 



106 



ORGANIC CHEMISTRY 



METHYL ALCOHOL, CH 3 -OH (Methanol or Carbinol) 

This is called wood-spirit, since it was obtained by Boyle in 1661 from 
wood-tar, and is to-day prepared in large quantities by distilling wood. Its 
chemical composition was not determined until 1834 (by Dumas and Peligot). 

In nature it occurs in the form of its salicylic ester, in Gaultheria pro- 
cumbens (in Canada) and as butyric ester in the bitter seeds of Heracleum 
giganteum. 

PROPERTIES. When pure it is a colourless liquid, b.pt. 66, with a 
faint alcoholic smell ; it burns with a non-luminous flame, solidifies at very 
low temperatures and melts at 94. When 1 kilo is burned, 5310 cals. 
are developed. It dissolves in all proportions in water, alcohol, ether, or 
chloroform. Its specific gravity at 15 is 0-7984, and in aqueous solutions 
the amount of the alcohol present can be determined from the specific gravities. 1 

Like spirits of wine (ethyl alcohol) it is intoxicating, dissolves fats, oils, &c., 
and when it is anhydrous it dissolves also calcined copper sulphate forming 
a bluish green solution. Jfrn 

It is more poisonous to the human organism than ethyl alcohol, since it 
produces fatty degeneration of the liver and undergoes changes quite different 
from those of ethyl alcohol, passing only in minimal quantities into the urine 
and being mostly oxidised in the organism. 

When heated with soda lime or with oxidising agents it readily yields 
formaldehyde and formic acid, and sometimes carbon dioxide ; r [when distilled 
with zinc dust it gives CO and H. With potassium it forms a crystalline 
alcoholate, CH 3 -OK, CH 3 -OH. 

INDUSTRIAL PREPARATION. In the laboratory methyl alcohol can be prepared 
by saponifying methyl chloride or iodide. Industrially, if wood is heated in retorts out 
of contact with air, after all the water has distilled over, gradual decomposition commences 
at 150, and between 150 and 280 acetic acid (about 5 per cent, of the weight of wood), 
acetone (0-1 to 0-2 per cent. ), methyl alcohol (0-5 to 0-8 per cent. ), certain ammonia bases, &c., 
distil over in the form of a reddish brown aqueous liquid of empyreumatic odour, termed 
wood-spirit, and containing about 10 per cent, of acetic acid, 1 to 2 per cent, of methyl 
alcohol and 0-1 to 0-5 percent, of acetone. Between 300 and 400 the distillate is mainly 
black, oily, dense wood-tar (about 10 per cent, of the wood), and at the fame time gases 
(about 6-5 per cent.) are developed which are utilised for heating the retorts. At the 
end of the distillation, charcoal (about 18 per cent.) remains in the retort?. If the distilla- 
tion is rapid, a greater yield of charcoal is obtained, whilst with slow heating more 
volatile and liquid products are obtained and only 9 to 10 per cent, of charcoal. 

As the principal product of the distillation of wood is acetic acid, the description of 
the apparatus employed in this industry will be left until later. 





Per 




Per 




Per 




Per 




Per 


Specific 


cent, by 


Specific 


cent, by 


Specific 


cent, by 


Specific 


cent, by 


Specific 


cent, by- 


gravity 


weight 


gravity 


weight 


gravity 


weight 


gravity 


weight 


gravity 


weight 


at 15-56" 


of 


at 15-56 


of 


at 15-56 


of 


at 15-56 


of 


at 15-56 


of 




alcohol 




alcohol 




alcohol 




alcohol 




alcohol 


0-99729 


1 


0-96524 


22 


0-93335 


42 


0-89358 


62 


0-84521 


82 


0-99554 


2 . 


0-96238 


24 


0-92975 


44 


0-88905 


64 


0-84001 


84 


0-99214 


4 


0-95949 


26 


0-92610 


46 


0-88443 


66 


0-83473 


86 


0-98893 


6 


0-95655 


28 


0-92237 


48 


0-87970 


68 


0-82938 


88 


0-98569 


8 


0-95355 


30 


0-91855 


50 


0-87487 


70 


0-82396 


90 


0-98262 


10 


0-95053 


32 


0-91465 


52 


0-87021 


72 


0-81849 


92 


0-97962 


12 


0-94732 


34 


0-91066 


54 


0-86535 


74 


0-81293 


94 


0-97668 


14 


0-94399 


36 


0-90657 


56 


0-86042 


76 


0-80731 


96 


0-97379 


16 


0-94055 


38 


0-90239 


58 


0-85542 


78 


0-80164 


98 


0-97039 


18 


0-93697 


40 


0-89798 


60 


0-85035 


80 


0-79589 


100 


0-96808 


20 



















METHYL ALCOHOL 107 

To separate the methyl alcohol from the liquid products of the distillation these are 
subjected to fractional distillation in copper boilers with a Pistorius rectifier (see Ethyl 
Alcohol), and when the specific gravity of the distillate has increased from 0-9 to 1 all 
the methyl alcohol (crude wood-spirit) has passed over and forms a greenish yellow liquid 
with a disagreeable odour. To eliminate the majority of the impurities the liquid is 
mixed with about 2 per cent, of lime, left overnight, and then distilled with the Pistorius 
rectifying apparatus, the acetic acid remaining fixed by the lime. 

The crude methyl alcohol thus obtained has a specific gravity of about 0-816 (93 per 
cent.) and is colourless, but it turns brown on standing in the air and becomes turbid on 
mixing with water. To purify it, it is diluted with water to the sp. gr. 0-935 (about 
40 per cent. ), left for several days, and after the superficial tarry layer which collects has 
been removed it is treated with 2 per cent, of lime and distilled almost completely. The 
distilled product is mixed with 0-1 to 0-2 per cent, of sulphuric acid and rectified, the 
concentrated alcohol distilling at 64 to 66, being collected separately ; this is used for many 
industrial purposes, although it contains a small proportion of acetone. The latter can 
be removed almost completely by transforming the alcohol into an ester (e.g. the oxalate, 
by treatment with concentrated sulphuric acid and potassium dioxalate), which is easily 
separated from the impurities ; by hydrolysing the ester with KOH, distilling and rectify- 
ing, pure methyl alcohol is obtained. The acetone can also be got rid of by combining 
the alcohol with CaCl 2 , giving the compound CaCl 2 , 4CH 3 -OH, which is stable at 100, 
so that the acetone can be distilled off at 56 together with the other impurities ; the 
residue is then decomposed with water and the pure methyl alcohol distilled. 

To ascertain if the alcohol still contains acetone, 10 c.c. of it are treated with caustic 
soda and an aqueous solution of iodine in potassium iodide ; no turbidity due to iodoform 
should be formed for some time. 1 

According to Farkas's patent (Ger. Pat. 166,360, 1904) alcohol of 92 to 95 per cent, 
purity is obtained direct if the vapours from the distillation of wood, while still hot, are 
passed through hot NaOH solution (15 to 20 B6.) and then into hot fatty acids, r the 
alcoholic condensate being rectified by passing the vapours into milk of lime. 

USES AND STATISTICS. Methyl alcohol is used for the manufacture 
of formaldehyde and various aniline dyes, for the preparation of different 
varnishes and for the denaturation of spirit (ethyl alcohol). 

1 Tests for Methyl Alcohol. When pure it should leave no residue on evaporation, should not have an 
acid reaction towards litmus, and should not contain ethyl alcohol, which can be detected as follows : a little 
of the liquid is heated with sulphuric acid, diluted with water and distilled, the distillate being treated with 
permanganate, then with sulphuric acid, and finally with sodium hydrogen sulphite ; if ethyl alcohol is not 
present this liquid will not give a violet coloration with fuchsine solution. Acetone and ethyl alcohol can also be 
detected by the iodoform reaction (Lieben's reaction : see below and also p. 101). Proportions of 2 to 3 per cent, of 
methyl alcohol can be detected by Scudder and Rigg's reaction (1906), which consists in treating 10 c.c. of the 
liquid at 25" with 5 c.c. of concentrated sulphuric acid and 5 c.c. of saturated permanganate solution, decolorising 
(after two minutes) with sulphurous acid solution and boiling until all smell of sulphur dioxide or acetaldehyde 
disappears. This liquid is then tested for formaldehyde by adding a few centigrams of resorcinol to 2 c.c. 
and pouring 1 c.c. of pure concentrated sulphuric acid to the bottom of the liquid ; a blue ring, due to the 
formaldehyde formed from the methyl alcohol, forms at the surface of separation of the two liquids. Deniges 
(1910) detects as little as 1 per cent, of ethyl alcohol by heating the methyl alcohol with bromine water and 
testing for the acetaldehyde formed with fuchsine solution decolorised with SO, (see Aldehydes). 

Estimation of the methyl alcohol in the commercial product is effected by the Krell-KrSmer method : 30 grms. 
of phosphorus tri-iodide is placed in a flask furnished with a long reflux condenser, down which is poured, drop by 
drop, 10 c.c. of the'methyl alcohol ; after a short time the methyl iodide formed is distilled from a water-bath into 
a graduated cylinder containing a little water ; when the distillation is completed, the condenser is rinsed out with 
water and the volume of the methyl iodide under the water measured at 15" ; 5 c.c. of pure methyl alcohol give 
7-19 c.c. of methyl iodide. 

The acetone is estimated by Kramer's method : in a 50 c.c. graduated cylinder with a ground stopper are placed 
10 c.c. of a 2N-caustic-soda solution, then 1 c.c. of the alcohol, and, after shaking, 5 c.c. of a 2N-iodine solution. 
After a short time 10 c.c. of ether free from alcohol are added, the liquid shaken and then allowed to stand ; the 
volume occupied by the ether is read off, an aliquot part of it evaporated to dryness on a tared watch-glass and 
the iodoform crystals dried in a desiccator and weighed : 394 parts CHI, correspond with 58 of acetone. 

A good commercial methyl alcohol should contain not more than 0-7 per cent, of acetone and at least 95 per 
cent, of the alcohol ; it should distil within 1 ; 5 c.c. of 0-1 per cent, permanganate solution should not be decolo- 
rised immediately when treated with 5 c.e. of the alcohol, and 25 c.e. of the alcohol, mixed with 1 c.c. of an acetic 
acid solution of bromine (1 part Br in 80 parts of 50 per cent, acetic acid) should give a yellow solution. 

Detection of Methyl Alcohol in Ethyl Alcohol. To 0-1 c.c. of the alcohol, in a test-tube, are added 5 c.c. 
of 1 per cent, potassium permanganate solution and 0-2 c.c. (not more) of pure, concentrated sulphuric add. The 
liquid is shaken and left at rest for 2 or 3 minutes, 1 c.c. of 8 per cent, oxalic acid solution being then added. The 
mixture i? again shaken and when it has assumed a brownish yellow coloration, 1 c.c. of concentrated sulphuric 
acid is added, decolorlsation then occurring in a few seconds. Five c.c. of rosaniline bisulphite are then mixed 
with the liquid, which is afterwards allowed to stand. With ethyl alcohol alone, an intense greenish to violet 
coloration is obtained, but this disappears after a few minutes. But if the alcohol contains even as little as 1 per 
cent, of methyl alcohol, the more or less blue coloration persists for several hours. 



108 ORGANIC CHEMISTRY 

In 1902, Germany produced 5000 tons of the pure spirit, of which 1151 
tons was exported, and imported 4273 tons of the crude product. In 1910 
England imported 448,500 galls, of methyl alcohol and exported 47,290 galls. 
The United States exported 1,691,000 galls, in 1910 and 2,040,000 (179,600) 
in 1911. 

Pyroligneous alcohol of 90 per cent, strength (French) is sold at 4 12s. 
per 100 kilos ; that of 92 to 93 per cent, strength (English) at 4 17s. 6d. ; and 
that of 95 to 96 per cent, strength for lacs at 5 Is. Qd. ; the purest methyl 
alcohol, free from acetone, costs 7 per 100 kilos. 

ETHYL ALCOHOL, C 2 H 5 -OH (Ethanol, Spirit of Wine) 

This is found rarely in nature (as butyric ester in Pastinaca sativa) and sometimes as 
an abnormal product in certain vegetables and animals, whilst it is easily formed by the 
alteration (fermentation) of various organic vegetable substances (saccharine juices, 
fruits, &c.)- It has hence been known from the most remote times. Aqua vitae or spirit 
of wine, obtained by distilling alcoholic beverages, was used as early as the eighth century 
and gave rise to an industry which acquired great renown in the province of Modena 
in the fourteenth century. Various European races learnt the use of aqua vitse from the 
custom introduced everywhere by the soldiers, who consumed large quantities of it during 
the wars of the Middle Ages. But very soon the northern peoples, who did not produce 
aqua vitae from wine, began to prepare alcohol by suitable transformations of the starch 
in the cereals abounding in their countries. By the beginning of the nineteenth century 
alcoholic liquors (exciting and enfeebling the nervous system and the brain) were spread 
over the whole of the civilised world and produced the terrible social scourge of alcoholism, 
much more disastrous in its material and moral consequences than all the other maladies 
that afflict humanity (see later, Alcoholism). Later, however, alcohol gradually acquired 
agricultural and industrial importance owing to its increasing practical applications in 
the arts and industries. Since 1830 Germany has extended the manufacture of potato 
spirit, and in many districts great agricultural advantages have followed the culture of 
this vegetable, since the waste products from the distilleries serve as nourishment for 
large numbers of cattle a source of great direct and indirect profit owing to the abundance 
of stable manure, which increases the fertility of the land and hence also the crops. 

SYNTHESIS OF ALCOHOL. In the laboratory alcohol can be obtained 
synthetically by hydrolysing ethylsulphuric acid, prepared from ethylene and 
concentrated sulphuric acid (Faraday and Hennel, 1828). Alcohol is formed 
by hydrolysing ethyl chloride, and, since ethyl chloride is prepared from ethane, 
which, in its turn, can be obtained from acetylene and hydrogen at 500 (or 
in presence of platinum black), the synthesis of alcohol from acetylene can 
be effected (Berthelot, 1855). Further, acetylene can be obtained from 
so-called inorganic substances, from C and H (Berthelot) ; by decomposing 
calcium carbonate with an acid, carbon dioxide is obtained, and magnesium, 
burnt in this gas, gives carbon, which, with lime, gives calcium carbide, and 
this, with water, acetylene ; there is hence a transformation of mineral sub- 
stances into organic substances. 

In 1907, Jonas, Desmonts, and Deglotigny (Fr. Pat. 360,180) proposed 
preparing alcohol by first forming acetylene in mercurous nitrate and then 
heating the mass to boiling ; the precipitate decomposes, regenerating the 
mercury salt and evolving vapours of acetaldehyde, which are condensed and 
converted into alcohol by means of sodium amalgam (nascent hydrogen). 

PROPERTIES. When pure, it is a colourless liquid with a characteristic 
odour, sp. gr. 0-7937 at 15, 0-80625 at ; it boils at 78-3 (or at 13 under 
21 mm. pressure), and its vapour is stable at 300 ; at a very low temperature 
it gives a glassy mass, which at 135 is converted into another solid mass 
m.pt. 117 (enantiotropy, vol. i, p. 191). 

When concentrated (absolute) it is extremely hygroscopic, and it mixes 



PROPERTIES OF ALCOHOL 109 

with water or ether in all proportions. To obtain absolute alcohol, i.e. 
absolutely free from water, fractional distillation is not sufficient, since at 
78-15 an aqueous alcohol containing 95-57 per cent, of alcohol by weight 
distils ; the higher alcohols also give mixtures with water which boil at 
lower temperatures than the corresponding alcohols. If benzene is mixed with 
alcohol, the latter can be obtained pure although a mixture of water and 
benzene first distils over, then alcohol (at 64-8), then alcohol and benzene 
(68-2) and finally pure alcohol. 

Usually absolute alcohol is obtained by distilling the ordinary 90 to 96 per 
cent, alcohol over calcined potassium carbonate or over anhydrous (i.e. calcined) 
copper sulphate, redistilling over lime and finally over baryta or a little sodium 
or calcium ; or it may be left over powdered aluminium until hydrogen ceases 
to be evolved. The aldehydes of the alcohol can be separated by boiling 
with 5 per cent, of caustic soda. 

If alcohol contains a little water, it becomes turbid on mixing with benzene, 
carbon disulphide, or paraffin oil, and turns white, calcined copper sulphate 
blue, and barium hydroxide is precipitated on addition of baryta, the latter 
dissolving only in the absolute alcohol. 

A mixture of 53-9 vols. of alcohol with 39-8 of water gives 100 vols., the 
contraction of 3-7 per cent, being due to the formation of a labile compound, 
(C 2 H 5 -OH) 18 ,H 2 (or 2H 2 0, &c.). It is a good solvent for resins, oils, colour- 
ing-matters, varnishes, ethereal essences and many other substances, and dis- 
solves sulphur and phosphorus to a slight extent ; it coagulates proteins and 
diffuses through porous membranes more rapidly than water. It dissolves 
and gelatinises soaps. 1 

It unites with various salts and alkalis as alcohol of crystallisation (KOH, 
LiCl, CaCl 2 , MgCl 2 ) (see p. 107). 

It oxidises easily, giving aldehyde and acetic acid, e.g. with potassium 
dichromate, Mn0 2 or even H 2 S0 4 , or oxygen in presence of platinum, or with 
micro-organisms if the solution is dilute. With concentrated nitric acid, it gives 
various oxidation products and with the dilute acid, glycollic acid. Alcoholic 
solutions of caustic alkalis turn brown, since they are partially resinified by 
the aldehyde which forms first and which acts as a reducing agent. Chlorine 
gives acetaldehyde and various intermediate chlorinated products. In a 
red-hot tube it decomposes, giving hydrogen and many hydrocarbons and 
acids. With sodium it gives sodium ethoxide in the form of a white powder. 

Absolute alcohol, which plays an important part in organic syntheses, is 
poisonous and rapidly produces death when injected into the blood. 

The complete combustion of 1 kilo of pure alcohol (C 2 H 5 -OH + 60 = 
2C0 2 + 3H 2 0) generates 7193 cals. and 96 per cent, alcohol, about 6750 cals. 

Alcohol can be detected even in traces (1 : 2000) by means of Lieben's 
iodoform reaction (see pp. 101 and 107). This reaction is also given by acetone, 
isopropyl alcohol, and the aldehydes ; according to Buchner (1905) it is 
preferable to heat the alcoholic liquid with a little paranitrobenzoyl chloride, 
which forms crystals of ethyl paranitrobenzoate, N0 2 -C 6 H 4 -C0 2 C 2 H 5 , 
m.pt. 57. In Rimini's reaction, the liquid is heated with sulphuric acid, and 
a dilute solution of potassium dichromate : the green colour of the solution and 
the odour of acetaldehyde are sufficiently characteristic, but the reaction can 
be confirmed by distilling a few drops of the liquid and treating the distillate 

1 Solid Alcohol is nothing but a soapy mass formed from about 20 per cent, of water, 20 per cent, of soap 
(sodium stearate) and 60 per cent, or more of alcohol ; it burns like liquid alcohol but leaves a residue. 

A richer product can be prepared by heating and stirring 100 parts of 96 per cent, alcohol at 60, dissolving 
1 part of stearine and adding 0-5 part of a 30 per cent, aqueous sodium hydroxide solution just sufficient 
to make it redden phenolphthalein. Some use a sodium soap charged with silicate (500 per cent.). A solid alcohol 
that burns without leaving a residue can be obtained by dissolving 20 to 40 parts of collodion in 100 parts of alcohol ; 
others add, instead, 25 parts of a 25 per cent, solution of cellulose acetate in acetic acid, and shake, the crust of 
solid alcohol which separates being squeezed out. 



110 ORGANIC CHEMISTRY 

with a little sodium nitroprussiJe and a drop of piperidine, a beautiful blue 
coloration being obtained if acetaldehyde is present. 

The manufacture of alcohol became One of the great chemical industries 
when a scientific explanation was obtained of the phenomena governing the 
transformation of starch and sugar. Fermentation, although known from the 
most ancient times, remained unexplained up to the nineteenth century, and 
it is solely, or largely, owing to the studies of Caignard de Latour and 
Schwann, Turpin, Schroeder, Liebig, Pasteur, Nageli, Cohn, de Bary, and, 
more recently, Duclaux, Buchner, &c., that the phenomena of fermentation 
are now completely explained and rationally regulated. 

In 1836 Caignard de Latour and Schwann found that the fermentation of wine and 
beer is strictly dependent on the germination of microscopic fungi which multiply in the 
must or wort. Turpin supposed that these fungi are nourished by the sugar, producing, 
as the excreta of their vital action, alcohol and carbon dioxide. In 1838 Liebig held 
that this transformation of sugar is caused by a special inter molecular movement due to 
substances contained in the ferment itself "(microscopic fungus). 

Pasteur, in 1872, showed that certain ferments that live at the expense of the oxygen 
of the air and can decompose sugar into water and carbon dioxide, when they are 
immersed in saccharine liquids, being no longer able to assimilate oxygen from the air, 
extract it from the sugar, resolving the molecule of the latter into alcohol and carbon 
dioxide. Although Nageli, in 1879, had attempted to reconcile the hypotheses of Liebig 
and Pasteur, yet up to a few years ago all fermentative phenomena were interpreted on 
the basis of the ideas enunciated by Pasteur. Progress in the fermentation industry 
proceeded, part passu, with that of bacteriology. 1 

1 Bacteriology is the science which studies morphologically and biologically the smallest, unicellular, 
vegetable organisms which are propagated with immense rapidity by segmentation. The cell is formed, as in the 
other organisms, of an extremely thin membrane which permits all the osmotic phenomena (see vol. i, p. 77), 
and encloses the protoplasm in which no central nucleus is visible, but in which there occur scattered granules 
(of starch and other substances), fat globules, vacuoles containing cell-sap, and sometimes crystals (e.g. of sulphur), 
while in certain bacteria the protoplasm holds various colouring-matters in solution. The temperature most 
favourable to their vitality varies, according to the species, from 5 to 40 ; they live, however, in a latent con- 
dition, at very low temperatures, although they do not reproduce, and they usually die at about 70 
(excepting the spores, tee below). As, in general, they do not contain chlorophyll, they are nourished by complex 
organic substances already elaborated by other organisms and hence soluble or capable of being rendered soluble 
(sugars, organic ammonium salts, ammonium compounds, &c.) ; and in this they are clearly differentiated from 
vegetable organisms and approximate more to the animals. Nutrient matter for bacteria always contains 
phosphorus, sulphur, potassium, and calcium, and, in certain cases, magnesium and manganese. They live well 
and reproduce rapidly in meat-broth or nutrient gelatine. They tolerate more easily alkaline than acid media 
and direct sunlight kills many species of bacteria, even pathogenic ones. As a result of their vital actions, sub- 
stances are sometimes formed which kill the bacteria themselves. Different antiseptics have various actions 
on different bacteria, or else only a specific action on certain of them. The reproduction of bacteria takes place 
ordinarily by segmentation, that is, when the cell has reached a certain length a thin wall forms in the middle and 
divides the cell into two new ones ; these divide, in their turn, so that the reproduction of these organisms, which 
increase in geometrical proportion (1, 2, 4, 8, 16, 32, &c.), proceeds with prodigious rapidity and yields millions 
of individuals in a few hours. The universal distribution of bacteria is thus easily understood. When the vital 
conditions are rendered abnormal or difficult for bacteria, in many of them there occurs a contraction of their proto- 
plasm into a more compact mass (at the centre or laterally, according to the species), which forms a separate 
individual, the spore, much more resistant to cold (180) and heat (130-140), and even to antiseptics than the 
corresponding bacterial cell ; the spores can retain life even for some years. Under favourable conditions, the 
spore breaks its envelope and gives a cell which reproduces by segmentation like the original one. Only certain 
rare species of bacteria are provided with chlorophyll or other colouring-matters capable of assimilating carbon 
dioxide under the action of sunlight. 

These micro-organisms, termed bacteria or schizomycetes or microbes, are those which produce putrefaction 
and infectious diseases (cholera, carbuncles, typhus, tuberculosis, small-pox, diphtheria, &c.) ; they are classified, 
according to their form, into: (1) Desmobacteria (bacillus or vibrio forms like small rods); (2) Sphere 
bacteria (cocci and micrococci of spherical shape and termed diplococci if united in twos, staphylococci if joined 
in bunches, and streptococci if in strings) ; (3) Spirobacteria (spirilla of twisted shape). To give a concrete idea 
of their forms de Bary described them as analogous to a pencil, a billiard ball, and a corkscrew. 

On the basis of their different activities and physiological properties Cohn divided all the species of bac- 
teria into three characteristic groups : (1) zymogenic, or those which produce all the non-alcoholic feimentations ; 
(2) ehromogenic, which produce various colouring-matters (red, violet, yellow, &c.) ; (3) pathogenic, which cause 
diseases of man and animals. To recognise the latter given the difficulty of distinguishing them morphologicaly 
under the microscope, since different species often have the same form and the same species sometimes several 
forms they are inoculated into the blood of living rabbits, rats, guinea-pigs, &c., the pathogenic character 
being deduced from the effects produced in the animals in two or three days, or sometimes even after a few 
hours. 

The lesser diameter (width) of these unicellular bacteria measures a few tenths of a micron (1 micron or /* = 
0-0001 mm.), and, in rare cases, as much as 1-7 M ; the greater diameter (length) is usually several microns. 

If we wish to indicate bacteria in a wider sense of the term, and not to limit them to the pathogenic or sapro- 
phylic (non-pathogenic) but still to those that produce all putrefactions and widen the limits of their dimensions, 



FERMENTATION 111 

During recent times, however, new facts have been discovered which have profoundly 
shaken the fundamental basis of this theory, according to which no fermentation is 
possible, except in the presence of certain species of living micro -organisms. In reality 
certain special fermentations are already known which are produced by enzymes, i.e. 
substances of complex chemical compositions which do not manifest anything in the 
nature of living micro-organisms ; for example, diastase transforms starch into maltose 
2(C 6 H 10 5 ). V + H 2 = aAaH^Ou. 1 

In 1900 Buchner succeeded in showing, by careful experiment, that some of these 
fermentations, which in the past could only be induced by the living micro-organisms, 
could also be effected by using the extract of the bacteria obtained by squeezing out, 
under great pressure, through special unglazed porcelain niters, the extract of the ferment- 
cells previously ground with quartz-sand. In this way Saccharomyces cerevisice yields 
maltase (which is an enzyme occurring also in germinating barley or maize and contained 
in Saccharomyces octosporus), which hydrolyses maltose, transforming it into glucose ; 
f i'om beer-yeast is obtained invertase (or invertin) capable of resolving saccharose or cane- 
sugar (not directly fermentable) into fructose and glucose (fermentable) ; fresh yeast 
calls yield zymase, the enzyme capable of effecting the alcoholic fermentation of various 
six-carbon-atom sugars (glucose, fructose, &c.). 

The action of the enzyme cannot be attributed to the still living protoplasm derived 
from the cells of the ferment, since the protoplasm can easily be killed in a mixture of 
alcohol and ether, and after this treatment the enzyme retains its activity. The action 
of ferments is hence due to the enzymes that they are able to produce, rather than to 
the biological phenomena of the life of the organisms. 

To-day numerous enzymes are known which, are of great importance in 
many vital functions of vegetable and animal organisms. It is not certain 
if the enzymes, with^their large and complex molecules, are true proteins, 
since up to the present they have not been obtained chemically pure ; all of 
them contain nitrogen but, as they are purified more and more, the nitrogen 
content continually diminishes and to-day it is held by some that the com- 
position of each enzyme approaches that of the substance it transforms ; so 
that diastase would be a substance similar to starch and poor in nitrogen, 
whilst the enzymes that transform the proteins would be of true protein nature. 
Proteolytic (decomposition of proteins) and fermentative actions only occur 

we can logically divide these micro-organisms into two other similar groups of similar beings, namely, the 
Hyphomycetes (moulds) and the Blastomycetes (ferments). 

The Hyphomycetes form groups of branched filaments (mycelia), which often subdivide into portions similar to 
bacteria, but the width of these always exceeds 2/x, and often 5/x ; they multiply by means of spores and four 
principal species are distinguished according to the mode of formation of these spores (conidia) : (1) the Aspergittus 
species which form, at the extremities of the fruit-bearing filaments (spore-bearing hyphce), a swelling in the form of 
a club covered with series of spores attached by means of intennediaFe steriymata ; (2) the Mucor species (or 
Mucedinece), in which the spore-bearing hyphse which start from the mass of mycelia carry sporangia (species of 
capsule) in which the spores develop ; (3) the Oidium species in which the spores are formed directly in the spore- 
bearing hyphae without any special organ of fructification ; (4) the Penicillium species, which is very common 
and has branched spore-bearing hyphse in the form of a brush containing series of spores AsperyiUus and Oidium 
are, however, not separate species but special sporifying forms of Eurotium and Erysiphw belonging to the order 
of Ascomycetes. 

The most important of these micro-organisms for industrial purposes are the Blastomycetes, i.e. the ferments 
or unicellular fungi which usually multiply by gemmation (budding), that is, by excrescences forming on the cells 
and becoming detached when they have reached a certain size, forming new cells which live independently of the 
mother-cells ; under abnormal conditions, however, the ferments multiply also by means of spores, four nuclei 
being usually formed inside the cell, these then becoming covered with membranes and dividing the mother-cell 
into four parts forming four new cells. 

The cells of the ferments have often a magnitude greater than 5/x, and the most important for alcoholic 
fermentation form the family of the Saccharomycetes (see later). 

The extraordinary beneficial influence of the bacteria and ferments in nature (apart from the pathogenic action 
of certain of them on some of the higher organisms) is manifested in the wonderful destructive activity they exert 
on the refuse and remains of all the higher organisms, converting the complex substances composing them into 
continually more simple substances until they give CO.,, H a O, NH,, and HNO,. These are the simplest materials 
which can be used by vegetable organisms to recommence the life-cycle, since in nature nothing is destroyed or 
created, but everything is transformed and thus life itself rendered eternal. 

1 Starch, which is formed in the green leaves, of plants under the action of sunlight and of chlorophyll, 
although an insoluble substance and very resistant to various reagents, emigrates during the night and accumulates 
in the seeds, roots (tubers), medulla, &c. We can, however, stop the starch in its path, and can explain how it 
can be transported by the juices into other parts of the plant. In fact, various enzymes occur distributed through 
plants, and among these is diastase or amylase, which renders the starch soluble by transforming it into soluble 
(and hence transportable by the juices) sugar (maltose), to be regenerated by an inverse process unknown to us 
in the form of insoluble starch in other parts of the plant. 



112 ORGANIC CHEMISTRY 

between certain limits of temperature (0-65) and are retarded or prevented 
by certain poisons (e.g. by traces of prussic acid or by metallic salts that act 
on proteins, like HgCl 2 , &c., although they are more, and sometimes completely, 
resistant to the action of antiseptics that kill ferments, such as salicylic acid, 
boric acid, ether, &c.). The various enzymes produce one or other of the 
following general reactions : hydrolysis (amylases, sucrases), coagulation 
(enzyme of rennet), decomposition (zymase of alcoholic fermentation), oxidation 
(laccase oxidises the juice of the lac-tree), &c. Enzymes exhibit different 
behaviour towards the stereoisomerides of certain hydrolysable and ferment- 
able substances (see section on Sugars). 1 

1 The following are some of the more important enzymes : 
Diastase (or amylase) occurs abundantly in malt (germinating cereals) but is found also in plants, the pancreas, 

the saliva, the liver, the bile, the blood, the kidneys, and the mucous membrane of the stomach and of the 

intestines ; it transforms starch into maltose and dextrin. 
Maltase transforms maltose into glucose, and is found in malt, in Saccharomyces cerevisice, and in plants and 

animals. 
Zymase causes alcoholic fermentation of glucose and is contained in yeast and the alcoholic ferments 

(Saccharomyces). 

Lactase decomposes milk-sugar. 

Melibiase resolves rafflnose (or cane-sugar) into molecules of more simple sugars. 
Invertase (sucrase, saccharase, or inverting decomposes saccharose into glucose and levulose, and is obtained from 

beer-yeast. 

Cytase or Cellase attacks cellulose. 
Maltodextrinase ferments maltodextrin. 
Dextrinase ferments dextrins. 

Peptase governs the important digestive functions of the stomach, and peptonises proteins. 
Tryptase is found in the pancreas and contributes to the peptonisation and decomposition of the proteins, 
Lipase is also found in the pancreas and renders the fats soluble (hydrolyses them). 
Emulsin, contained in bitter almonds, and capable of decomposing amygdalin. 
Ptyaiiii is contained in the saliva and initiates the digestion of starchy foods. 
Reductase is capable of effecting reduction phenomena, especially in presence of aldehydes, and is hence also 

known as aldehydo-catalase ; it decolorises Schardinger' s reagent (mixture of methylene blue and 

formalin). Reductase is widespread in the animal kingdom and occurs in unboiled milk (boiled milk is 

detected by the lack of this enzyme ; it does not decompose water or decolorise guaiacol). 
The Oxydases form a group of enzymes (laccase, tyrosinase, aenoxydase, catalase, &c.) capable of effecting 
oxidations by fixing the free oxygen of the air and transferring it, in the nascent state, to the substances to be 
oxidised. They occur widespread in the vegetable kingdom and are also found in the animal kingdom, and their 
oxidising action is comparable to that of platinum black (catalyst). In fact the catalase found in the blood is 
capable of decomposing H 2 O 2 , giving nascent oxygen and water (Loew, 1901). It is now found that the oxydases 
are formed of mixtures of oxygenase and peroxydase. Euler and Boliu (1909) obtained a laccase of the Medicago 
type in a chemically pure state, and found it to be composed of calcium salts and a small amount of iron salts 
of mono-, di-, and tri-basic hydroxy-acids, especially citric, malic, mesoxalic, and glycollic acids. 

Peroxydases and Oxygenases. Schonbein (1856) had observed that certain vegetable and animal 
organisms contain substances analogous to ferments and capable of decomposing hydrogen peroxide catalytically 
with liberation of oxygen, and also of accelerating catalytically this decomposition (i.e., the oxidising action) 
in the same way that ferrous sulphate does. Loew (1901) showed that the first action is due to a special enzyme, 
catalase (oxygenase). Linossier, in 1898, succeeded in separating from pus an enzyme free from oxydase (oxygenase), 
yet capable of accelerating but notof initiating the decomposition of hydrogen peroxide ; this he called peroxydase. 
The oxydases and peroxydases often occur together and they may be separated by heating the mixture to 70, 
the oxydase being thus killed, or, as was proposed by Aso of Tokio (1902), by dissolving the peroxydase in alcohol 
which does not dissolve the oxydase, or by poisoning the latter with sodium fluoride or fluosilicate. There are 
also several plants that contain only peroxydases, among them pumpkins and horse-radish roots (Bach and Chodat, 
1903, 1906). 

The peroxydases are nitrogenous but non-protein substances, and, when heated with NaOH give NH 8 ; they 
always contain about 6 per cent, of ash, 0-8 to 1-4 per cent, being aluminium and 0-2 to 0-6 per cent, manganese. 
The peroxydases dialyse, whilst the oxygenases do not. The specific action of the peroxydases consists in activating 
in a remarkable manner the oxidising action of H 2 O, on organic substances, e.g. gallic acid, pyrogallol, &c. ; they 
activate also the action of the peroxides that form in organic substances by the action of the oxygen of the air 
(e.g. ethereal oils, turpentine, &c.). 

In 1897 Bertrand introduced the following hypothesis to explain the action of the oxydases : the latter are 
regarded as hydrolysable manganous protein compounds, in which the manganese, in the mauganous condition, 
is the transmitter of oxygen from the air to the oxidisable substance ; the manganese dioxide formed would then 
be again reduced by the protein acid radical, the original manganous protein compound being regenerated. Bach 
and Chodat have, however, found manganese in the peroxydases, although these are not direct oxidising agents. 

The peroxydases have no oxidising action, unless a peroxide is present. They do not turn fresh guaiacol 
tincture blue, but after some hours this change does occur, the tincture having formed peroxide, which can be detected 
by starch and potassium iodide solution. Whilst the peroxydases accelerate the decomposition of very dilute 
H 2 O 2 , this kills them if concentrated. In 1908 J. Wolff obtained the reactions of the peroxydases by traces of 
ferrous sulphate or copper sulphate. The oxidising action of the oxygenases (which have, however, not yet been 
obtained free from peroxydases, although the latter are known free from oxygenases) is only weak and is strongly 
activated by addition of peroxydase. On the other hand, it seems established that there are two species of peroxy- 
dases existing, the one activating strongly the oxygenases and feebly the decomposition of H 2 O 2 , and the other 
behaving in the opposite way. The character of the oxydases themselves is indicated by the specific action of one or 
the other species of peroxydase. Indeed, Bertrand had in 1896 extracted from certain plants, e.g. young potato 
tubers) an oxydase which differed from all others in not oxidising phenols or the aromatic amines, whilst it oxidised 
and blackened tyrosine, which is not altered by the ordinary oxydases or even by the presence of H,O a alone. 
Bach (1906) succeeded in separating the specific peroxydase from tyrosinase and in showing that this peroxydase 



ENZYME ACTIONS 113 

But still more interesting is the fact that during an ordinary fermentation the amount 
of sugar fermented does not depend closely on the quantity of living ferment or enzyme ; 
thus large quantities of sugar can be decomposed by small quantities of ferment or enzyme. 

The action of the enzymes and of the ferments may be logically compared with that 
of the inorganic catalysts (vol. i, p. 67), which only produce an enormous increase in the 
velocity of reaction, in our case, of the decomposition of sugar. And that these organic 
catalysts have an action really similar to that of the inorganic catalysts can be shown by 
certain other interesting facts. 

Some years ago Duclaux succeeded in producing alcoholic fermentation by dilute 
alkali ; Traube in 1899 transformed sugar into alcohol by means of finely divided platinum 
alone at 160 ; while Schade in 1906 converted an alkaline solution of glucose, in absence 
of enzyme, quantitatively into acetaldehyde and formic acid (C 6 H 12 O 6 =2C 2 H 4 O +2CH 2 O 2 ), 
and these products, under the catalytic influence of rhodium, are transformed quantitatively 
into C0 2 and alcohol (perhaps the formic acid first gives C0 2 and H 2 , the latter, in the 
nascent state, reducing the aldehyde to alcohol). 1 

Further, as in chemical equilibria (vol. i, p. 62), the action of catalysts in 
reversible reactions is regulated by conditions of temperature and of con- 
centration different from those met with in the case of enzymes : indeed, 
when diastase has converted a certain quantity (dependent on the temperature) 
of starch into maltose, the hydrolytic change is arrested (i.e. equilibrium is 
reached in the reversible reaction : starch t; maltose) ; but if part of the 
maltose is fermented into alcohol and C0 2 , the equilibrium is disturbed and 
the diastase hydrolyses a further quantity of starch. Also at temperatures 
above 55, diastase forms dextrin in preference to maltose. An analogous 
phenomenon is observed in the hydrolysis of amygdalin by emulsin. It has 
already been mentioned that maltase transforms maltose first into glucose, 
but when a certain proportion between these two products is reached, the 
hydrolysis ceases owing to equilibrium being attained : C 12 H 22 U + H 2 ^ 
2C 6 H 12 6 , and the transformation proceeds only when the glucose is removed 
by alcoholic fermentation ; Emmerling has realised the inverse reaction 
by displacing the equilibrium by addition of glucose (in which case isomaltose 
is produced). 

is only capable of causing the oxidation of tyrosine when mixed with the corresponding oxygenase or in presence 
of H 2 O a alone. Hence the action of tyrosinase is due to the specific action of its peroxydase. Bach holds further 
that in the phenomena of respiration of organisms, oxidation due to oxydases plays no part, since this leads to 
true condensations, to syntheses of more complex products ; for respiratory phenomena there should exist euzymes 
of a type not yet known and capable of decomposing and oxidising there serve materials of the organism (fats, 
carbohydrates, &c., which are not oxidised by oxydases). 

At the present day the catalytic action of the enzymes is explained as due to small quantities of metal which 
they contain ; thus the important action of the haemoglobin of the blood (which fixes the oxygen in the lungs 
in a labile condition and transports it to all parts of the organism) appears to be due to the small quantities of 
iron present, this inducing the decomposition of the food materials ; thus the synthetic action of the peroxydases 
is perhaps due to the manganese they contain (see above), just as the important synthetic functions of chlorophyll, 
according to Willstatter's recent work, appears to be owing to the magnesium present in it. Recently (1910) 
Bach has, however, succeeded in preparing very active oxydases and peroxydases free from iron and manganese, 
so that the true explanation of the activity of these enzymes remains to be discovered. 

1 Buchner and Meisenheimer (1909) explain the action of ferments, from the chemical point of view, by the 
addition of a molecule of water to the sugar and abstraction of an atom of oxygen by the ferment, so that there 
results, as an unstable intermediate product, a dihydric alcohol, which, in its turn, is immediately decomposed 
into H 2 and 2 mols. of dihydroxyacetone ; the last product is able to decompose into CO 2 and alcohol, while the 
hydrogen continues to transform fresh quantities of sugar into the dihydric alcohol, and so on. Boysen-Jensen 
(1909) finds that the reactions for dihydroxyacetone are given by fermentations ; the decomposition would hence 
take place thus : 

CH 2 OH CH 2 OH CH 2 OH 

CH, 
CHOH CHOH CO - CO. + 

C'llj,- UJ1 

CHOH CHOH CH,OH 

+ H,0 = O + . - H 2 + p H ' OH 

CHOH CHOH 

CH, 

CHOH CHOH CO ~* C0 2 + - 

CH 2 -UH 

CHO CH,OH CH.OH 

Glucose Dihydric alcohol 2 mols. of 2 mols. 

Dihydroxyacetone of Alcohol 

ii 8 



114 ORGANIC CHEMISTRY 

Also in the action of maltase on amygdalin, Emmerling succeeded in 
producing the reverse reaction, and at the St. Louis Exhibition in 1904 he 
showed a fine specimen of amygdalin prepared synthetically by an enzymic 
process. 1 

So that with one and the same enzyme, analytic and synthetic processes 
can be effected. Cremer obtained glycogen (C 6 H 10 5 ) y from levulose by 
means of an extract of yeast, and Hanriot, Kastle, and Loewenhart prepared 
monobutyrin and butyl acetate synthetically by means of lipase. The 
enzymes also effect the so-called asymmetric syntheses, i.e. they give optically 
active compounds containing asymmetric carbon (1908). 

Also interesting is the fact that a single ferment may contain various 
enzymes ; thus, from Saccharomyces cerevisice, maltase and invertase can be 
extracted easily and also zymase, though with more difficulty. 

These recent discoveries on the reversibility of the reactions effected by 
enzymes are of great importance, as it was at first thought that enzymes or 
ferments in general were capable of causing only decompositions and not 
synthetical reactions, whereas their analogy with inorganic ferments is now 
complete. But the discoveries are all the more remarkable, since the same 
phenomenon of vitality in the single cell as in more complex organisms 
can be reduced to an enzymic phenomenon ; that is to say, the exchange of 
material in the organism (decomposition, recomposition, growth) takes place 
by means of these organic catalysts, which cause the decomposition of food, 
preparing various complex materials which form the organism itself, and at 
the same time generating the energy manifested in the vitality, enzymic 
phenomena being always exothermic. This hypothesis can, with advantage, 
be substituted for the too abstract biogen z hypothesis, to explain vital 
phenomena. 

1 C.Hs-CHfCI^-C.HnOo + C.H 1S 8 ; C 20 H 27 NO n + H 2 O 

Glucoside of phenylgly- Maltase Amygdalin 

collie nitrile 
or, more completely : 

2CH 12 O, + HCN + C 6 H,,-CHO ^ 2H 2 O + C 20 H 2 ,XO U 

Glucose Hydrocyanic Benzal- 

acid dehyde 

Hypotheses of Biogen, Toxins, and Genesis of Life. The physical and physiological basis of life resides 
especially in the protoplasm, the semi-fluid, almost always colourless, refractive substance insoluble in water 
which everywhere constitutes the essential part of the cell. Protoplasm is formed principally from protein sub- 
stances, whilst it is thought that the fats and carbohydrates are not active components. To the protoplasm is 
attributed the fundamental property of vitality, i.e. the exchange of material, but it is not known how its com- 
ponents the proteins can have such properties or in what physico-chemical aggregation of the proteins (the plasti- 
dules and bionomads are regarded as morphological components or units of protoplasm) they have their orign. 

In animals one of the principal functions of the blood is that of supplying the respiratory needs of the tissues 
in virtue of the haemoglobin contained in the blood of vertebrates [besides fibrinogen, serum-albumin, and para- 
globulin; whilst with the invertebrates there are echinochrom, chlorocruorin, hcemoerythrin, hcemocyanin (con- 
taining copper), and pinnoglobin (containing manganese), which have the same functions as hsemoglobin] ; it is 
formed of a protein substance united with a ferruginous compound, which takes up oxygen at the respiratory 
surfaces of the organism (skin, bronchi, and lungs), and brings it into close contact with the tissues. 

The vital processes of the organism being due to the exchange of material in the cells full of protoplasm, the 
biogenic hypothesis assumes that this is brought about by a very complex, labile compound, which, by being con- 
tinually decomposed and reconstituted, maintains the interchange uninterruptedly. By many this compound 
is called living albumin, but Max Verworn (1895 and 1902) regards this as an unsuitable name and does not think 
it has been shown to be a true albuminoid, although it is a nitrogenous substance ; there arc possibly several sub- 
stances in a state of labile combination and these he calls molecules of biogen. 

It has been observed that in organisms, as in parts of them, vitality ceases when oxygen is eliminated, many 
of them subsequently (the frog even after twenty-five hours) recovering it in presence of oxygen. From this arise 
two hypotheses : (1) the molecule of biogen becomes labile, and hence gives rise to decompositions and recompo- 
sitions, that is, to the vital process since it unites transitorily with oxygen ; (2) oxygen serves only to oxidise 
or eliminate the decomposition products of the biogen (admittedly labile), and when there is no oxygen, these 
products are not eliminated, so that the decomposition and recomposition of the biogen arc arrested. By 
experiments on the frog Max Verworn has shown that the foimer hypothesis is the more probable. 

Since, in the vital process, under the action of oxygen, it is especially the carbon dioxide that is eliminated, 
often along with lactic acid, water, &c., whilst the elimination of nitrogenous substances does not increase, it may 
be assumed that biogen is constituted of a benzene nuckus with lateral chains of carbohydrate and aldehydic 
character and with an oxygen-carrying nitrogenous group which fixes the oxygen of the air (just as NO gives 
NOj in the lead-chambers of sulphuric acid works) and gives it up to the lateral chain, which is oxidised (Ehrlich's 
side-chain hypothesis, 1882-1902) to CO 2 , lactic acid, H.O, <fcc., these being eliminated ; the nitrogenous group, 
thus reduced, remains united with the benzene group, wh'ch, with new food,' oims the biogen molecule, this 



TOXINS AND ANTITOXINS 115 

In order to ascertain if a given action is due to enzymes or to organised 
ferments, the liquid is passed under pressure through a Chamberland porous 
porcelain filter, which retains the ferment cells, but not the enzymes ; the 

being again decomposed by oxygen and so on. The digested food^inaterials carry, with the blood, new materials 
to the regeneration of biogen (without food, death ensues), the oxygen then effecting the changes described above. 
The seat of the biogen lies in the liquid protoplasm of the cell (not in its nucleus), into which oxygen enters in the 
state of labile combinations not yet defined but capable of giving it up when needed : these compounds are more 
stable in the cold than in the hot and are those that carry on the vitality during prolonged fasts. These reserve 
materials are probably formed by the decomposition of the food by means of intracellular enzymes, which form the 
connecting-link between the living substance (biogen) and the non-living (foods), transforming the latter into 
the former. 

The biogen hypothesis is opposed by that of the enzymes as factors of the vital process and, given the varied 
nature of the phenomena and of the chemical transformations occurring in the living organism, and the variety 
of the numerous chemical groups forming a protein molecule, it is perhaps imprudent to refer all these phenomena 
to a single compound, biogen, when we already know different enzymes which certainly effect well-investigated, 
definite reactions. From the action of different enzymes on the protein complex forming the protoplasm of the 
cell, there results the many-sided phenomenon of vitality. And in certain cases it is possible to go still further, 
as it must be admitted that many synthetic and analytic phenomena of organic substances (e.g. the fermenta- 
tion of sugar) take place even without protoplasm, by the direct action of the enzyme alone (see p. 111). 

Further, by simple catalytic actions, it is now possible to effect artificial fertilisation (artificial parthenogenesis) ; 
for example, by treating unfertilised eggs of the sea-urchin with solutions of various chlorides, best of all, 
magnesium chloride, Loeb (1899 and 1900) obtained living larvae ; Giard (1904) studied the artificial partheno- 
genesis of the star-fish (Asteria rabens) ; Tichomiroff (1886 and 1902) and, better, Quajat at Padua (1905) obtained 
partial artificial parthenogenesis of the virgin eggs of the silk-worm. 

Most interesting of all are the investigations on sero-therapy which have led to the most unexpected results 
when, instead of the observations being limited to the bacteria, the poisonous or beneficial substances which 
they elaborate or secrete have been considered. These toxins or antitoxins secreted by bacteria or formed in 
animal organisms also appear to be enzym'es, exhibiting, however, their activity in phenomena of a different and 
more complex nature 

In the last few years (1902-1907) Arrhenius, in conjunction first with the head of the German school, Ehrlich, 
and later with that of the Danish school, Madsen, has devoted himself to the interpretation of sero-therapy, making 
effectual use of all the modern laws of physical chemistry. He has succeeded in following and controlling the 
formation and action of toxins and antitoxins in the animal organism by empirical mathematical formulae, 
calculated beforehand from the results of previous experiments ; and it is not improbable that the time will 
soon arrive when from these empirical formulae, suitably co-ordinated, rational formulae will be derived leading 
to new and important natural laws, from which general pathology will obtain great principles rendering it possible 
for man and other animals to be immunised against the attacks of pathogenic bacteria. Then, and only then, 
will man have triumphed over the microbe. 

By injecting more or less poisonous substances (toxins) into the animal organisms, the so-called anti-bodies 
(antitoxins) are formed in the blood, but their formation is probably incomplete in consequence of the laws 
of chemical equilibria discovered by Guldberg and Waage (vol. i, p. 62). 

The corresponding antitoxins are known for only a few poisons. Those of solanine and saponin (1901) 
and of morphine (aniimorphine) (1903) have been sought for in vain by inoculating guinea-pigs and rabbits, so 
that these three poisons are not to be regarded as toxins. From castor-oil seeds ricin has been extracted 
a toxin for which the corresponding antiricin is known ; also, seeds of Abrus prcecatorius and Robinia pseudacacia 
yield the poisons abrin and robin, for which the corresponding antitoxins have been obtained. Animals also 
produce anti-bodies of non-poisonous substances ; thus, if any cells whatsoever are injected into the blood, anti- 
bodies are more or less rapidly produced which have a special destructive action on these cells. Also by injecting 
rennet (which coagulates milk) an antirennet is obtained which is able to prevent the coagulating action of the 
rennet. 

From pathogenic bacteria are obtained anti-bodies (by inoculation) to certain proteolytic eusymes : in 1893 
Hildebrandt found an anti-body to emulsin and Gessard (1901) prepared an anti-body to tyrosinu.se (see above) ', 
from the serum of a goose inoculated with pepsin, H. Sachs (1902) obtained an antipepsin ; A. Schutze (1904) 
obtained antilactase by making subcutaneous and intermuscular inoculations with the lactase of kephir (which 
see), and similarly were prepared anti-bodies to cynarase, zymase, urea.se, and the fibrin and pancreatic ferments. 

It is difficult to establish a limit or any essential difference between enzymes or ferments and toxins, and 
the preparation of anti-bodies to all these active substances is, perhaps, only a matter of time. The anti-bodies 
are divided into two classes, according as they are obtained by inoculation of homogeneous solutions (toxins) 
or of emulsions of bacteria or cells (red blood corpuscles), <fec. The anti-body formed by the inoculation of a 
homogeneous solution combines with the toxin of the latter, forming an innocuous substance, which is called 
an antitoxin if soluble or a precipitin if insoluble. The injection of bacteria sometimes leads to the formation 
of anti-bodies capable of dissolving the bacteria themselves (from which they are derived) and then these anti- 
bodies are termed lysins (bacteriolysins). There may also be formed anti-bodies which agglutinate the inoculated 
cells, i.e. agglutinins, but this depends on the presence of salts. The cholesterin and lecithin of the organism 
often form part of the toxin or antitoxin. Cholesterin, for example, acts as an antitoxin to tetanolysin and 
other lysins. According to Metchnikoff it is the leucocytes (white corpuscles) which produce the antitoxins, 
but this has not been rigorously proved, although Wright has shown that certain anti-bodies (opsonins) exhibit 
their activity against bacteria only in presence of leucocytes. 

That the action between toxins and antitoxins resembles chemical neutralisation was assumed at the time 
of the discovery of the first diphtheritic antitoxin by Bearing and Kitasato in 1890, and was supported by the 
German school with Ehrlich at its head. From 1893, however, the French school (Roux, Vaillaid, Metchnikoff, 
and also Buchner)_ held that the antitoxins exert a physiological action, exciting, as it were, the organic tissues 
to resist the attacks of these poisons (toxins). When, however, Ehrlich showed that the agglutinating action 
of ricin on the red blood corpuscles (suspended in physiological serum, that is, in 0-9 per cent. NaCl solution) 
could be annulled by simply adding antiricin, and because he showed that the neutralisation of the action of 
a given quantity of toxin required the presence of a proportionate amount of antitoxin, most scientific men 
abandoned the physiological hypothesis. Ehrlich's more recent studies on the action of two arsenical compounds 
on the toxins have led to the cure of sleeping-sickness and probably to that of syphilis (by means of the product 
606). In suitable conditions of temperature, &c., the original toxins can be regenerated from the antitoxins 
by a reversible process (Reversible Reactions, vol. i, p. 63) ; this was shown by Morgenroth (1905) by dissociating 



116 

filtered liquid is then examined to ascertain if it still produces the enzymic 
action. Or the liquid may be mixed with chloroform, which arrests all cellular 
life, but does not act on the enzymes. 

A liquid containing an enzyme is coloured blue by the addition of an 
alcoholic solution of guaiacum resin, previously mixed with a drop of hydrogen 
peroxide. 

The enzymes are, as a rule, destroyed by boiling. 

INDUSTRIAL PREPARATION OF ALCOHOL. As already mentioned, 
the prime materials are saccharine or starchy substances ; the latter, by the 
action of enzymes (diastase and maltase) are transformed into maltose and 
glucose, and then by the action of the zymase contained in yeast-cells (species 
Saccharomyces, see pp. Ill and 121) the glucose is transformed, to the extent 
of 95 per cent., into alcohol and C0 2 , with evolution of heat. 

The treatment of the starchy materials is carried out as follows : the 
starch is obtained from various prime economic materials, namely, maize 
(especially in Italy, Hungary, and America), potatoes (Germany, France, 
England, and Russia ; attempts to introduce the potato industry into Italy 
have as yet come to nothing) ; cereals (Russia and England) ; rice (England, 
Japan, China, Italy). 

There are two practical processes : (1) the action of dilute mineral acids 
in the hot, and (2) the action of certain hydrolytic enzymes (like diastase 
contained in malt). 

(1) Transformation of starch by dilute acids. In this transformation, starch yields 
glucose almost quantitatively : (C 6 H 10 O 6 ) n (starch) + nH 2 O = C 6 H 12 O 6 , and we shall 
deal more in detail with this process later on, in the section on Glucose, At present 
only the second process will be considered. 

(2) Transformation of starch by means of enzymes. Of the enzymes, that which 
is of the most service industrially, is diastase. It is formed more especially during 
the early stages of the germination of cereals (maize, barley, &c.), and this germinated 
gram forms malt which is most favoured by a temperature of 45-55 in its transformation 
of starch into dextrins (amylodextrin, erythrodextrin, achroodextrin, (C 12 H 2 o0 1 o). v ) and 
into maltose and isomaltose, C^H^On. 

As has been already mentioned (p. 113), this reaction is regulated by the 
laws of chemical equilibria, and depends especially on the temperature : 

the antitoxin with a little HC1 and destroying the anti-body at 100. So that validity can no longer be ascribed 
to the hypothesis of Behring (1890), Nernst (1904), and Biltz, Much, and Siebert (1905). according to which the 
toxins are absorbed by the colloidal antitoxins and then destroyed. 

The toxins and antitoxins, although colloidal substances, diffuse easily and give osmotic pressures according 
to van 't Hoff's law. 

Toxins diffuse through water and gelatine much more rapidly than antitoxins, so that a mixture of the two 
bodies can be separated into its components. The difference in the rapidity of diffusion depends on the molecular 
magnitudes (according to E. W. Reid, haemoglobin has a molecular weight of 48,000). The molecular weights 
of the antitoxins would be 10 to 100 times as great as those of the toxina. 

The velocity of reaction of the different toxins does not depend, as Morgenroth supposed, on catalytic actions, 
but, as Arrhenius and Madsen showed, on the temperature, and is regulated by a law deduced from thermo- 
dynamical considerations based on van 't Hotf's laws of solutions. 

A number of other factors of the vitality of the organism digestion of food, assimilation of carbon dioxide 
by plants, development of the egg, production of alcohol during the fermentation of sugar, &c. are due to 
enzymes or toxins and antitoxins, whose actions are regulated by the laws of chemical equilibria and of the 
velocity of reaction, and are perhaps not disconnected from catalytic phenomena or from reactions similar to 
or identical with those assumed by the biogen and side-chain hypotheses. 

Further, the recent studies of O. Lehmann and of S. Leduc (1896) on Liquid Crystals, according to 
which, under certain conditions, solutions of substances can assume the form of crystals or of cells that grow, 
multiply, and die, like actual organisms (see vol. i, p. 112), furnish a probable explanation of the transition from 
organic substances to organised bodies. Thus, after what has been stated above, the entire cycle of the genesis 
of life can be comprehended, from the transformation of inorganic substances into organic (see p. 108) and of 
these into organised (or living), by hypotheses based on scientific" facts. It still remains, however, to explain 
the origin of the inorganic world, terrestrial and extra-terrestrial, the answer of science being that, in accordance 
with Lavoisier's law, nothing is created and nothing destroyed, so that the inorganic world has always existed 
and is eternal, and eternal also is its continuous evolution. This is the actual limit of human knowledge, which, 
in its imperfection, cannot explain the infinite and the eternal. And no metaphysical philosophy has succeeded 
in obtaining a final clue to this secret of eternity, since it is not a plausible or even rational explanation to refer 
the eternity of the inorganic world to a hypothetical, abstract, supernatural being who created everything from 
nothing, in contradiction to the fundamental laws of positive science, the fast of all of these being those of the 
conservation of mass and of energy. 



MANUFACTURE OF ALCOHOL 



117 



between 45 and 50 maltose is preferably formed, and at about 60, 
dextrin. 

We have already noticed how maltose is transformed into glucose by means 
of maltase, and how the chemical equilibrium is displaced, by gradually trans- 
forming the glucose into alcohol by fermentation. 

Of the various malts used industrially, that of barley is the most active, then follow 
wheat and rye, and, finally, maize ; the last named is one-third less active than that of 
barley, but owing to its low price has practical advantages, and in Italy is the one most 
commonly used. 

In describing the industry of brewing, we shall deal in detail with the practical manu- 
facture of malt, and we would refer the reader to that section for a description of the 
preparation of maize malt, which does not differ from that of barley malt. 

As regards the use of chlorine dioxide to increase the germinative power of maize, 
as proposed by Effront, see vol. i, p. 171. 

The starchy matters forming the starting materials of the alcohol industry (cereals, 
potatoes, &c.) cannot be subjected to the action of diastase unless their starch is first 
transformed into a semi-solution (starch-paste) by treating with water or steam at a high 
temperature ; the starch-granules swell and then burst and readily assimilate water 
(potato starch at 65, maize starch at 75, barley starch at 80). The materials are hence 
first steeped and ground, and then extracted with hot water, to be subjected subsequently 
to saccharification with malt and finally to alcoholic fermentation. 

The following Table gives the amounts of starchy and extractive matters per 100 kilos 
of various materials, together with the theoretical yields of alcohol : 



Wheat . 

Maize 

Barley 

Rye '. : . 

Rice 

Durra 

Green potatoes 

Dry potatoes . 



Starchy and extrac- 
tive matters 

65-68 kilos 

62-67 

63-65 

66-69 

78-82 

61-64 

18-20 
68-70 



Alcohol 

32-44 kilos 

31-33 

30-32 

34-35 

39-43 

30-32 

10-12 
34-35 



In washed potatoes the starch is calculated from their specific gravity (vol. i, pp. 72 
and 107). 1 

In cereals and potatoes the content of starch can be determined as follows : 200 grms. 
of potatoes (75 grms. of ground cereal) are heated in a flask with 600 c.c. of water and 
10 c.c. of hydrochloric acid (sp. gr. 1-2 =i 4-7 grms. HC1) for ten hours at 90, the volume 
made up to 1 litre and 3-5 grms. of HC1 neutralised with caustic soda (leaving 1 grm. 
free) ; the whole is poured into a larger flask, a few grammes of beer-yeast being added 
and the flask kept at 25 for 2 or 3 days until the fermentation is over, when half of the 



Specific 


Per 


Specific 


Per 


Specific 


Per 


Specific 


Per 


gravity of 


cent, of 


gravity of 


cent, of 


gravity of 


cent, of 


gravity of 


cent, of 


potatoes 


starch 


potatoes 


starch 


potatoes 


starch 


potatoes 


starch 


1-070 


11-5 


1-088 


15-6 


1-106 


19-4 


1-125 


23-5 


1-072 


11-9 


1-090 


16-0 


1-108 


19-9 


1-127 


24-0 


1-074 


12-5 


1-092 


16-4 i| 1-110 


20-3 


1-129 


24-5 


1-077 


13-1 


1-094 


16-9 


1-113 


20-9 


1-134 


25-E 


1-079 


13-7 


1-097 


17-5 


1-115 


21-4 


1-139 


26-f 


1-081 


14-1 


1-099 


17-9 


1-118 


22-0 


1-144 


27-6 


1-083 


14-5 


1-101 


18-4 


1-120 


22-5 


1-149 


28-7 


1-085 


14-9 


1-103 


18-8 1-122 


22-9 


1-150 


28-9 



(To 15 per cent, of starch corresponds 20-8 per cent, of dry matter in the potato ; to 20 per cent, of starch 
25-8 per cent, of dry matter ; and to 25 per cent, of starch 30-8 per cent, of dry matter). 



118 



ORGANIC CHEMISTRY 



liquid is distilled and the alcohol estimated in the distillate by means of the specific gravity. 
100 kilos of starch yield practically 63-5 litres of alcohol. 1 

The fresh potatoes are washed free from stones and earth in an Eckert mechanical 
washer (Pig. 103), passing first into a rotating sieve, E, which removes the stones and, 
by means of the blades, F, carries the potatoes into the tank, A, through which water 
flows and in which they are stirred by the vanes, C, fixed to a rotating axis ; the latter 
is inclined in such a way that the potatoes are gradually forced to the far end of the tank 
where a rotating disc, furnished with perforated blades, collects them and removes them 
from the tank. An elevator raises them to the opening of a Pauksch's improved form 
of the conical Henze autoclave (Fig. 104), which is made of sheet-iron, has a volume of 
2500-3000 litres, and takes about 1500-3000 kilos of potatoes ; in this they are treated 
for an hour or more with steam at 2-5 to 3-5 atmos. pressure. Such an apparatus can 
also be used for treating maize and other cereals, and gives a much denser wort than was 
previously obtained when steam at 100 was used ; in addition, it effects a better dis- 
solution of the starch, and is of advantage to manufacturers in countries where the alcohol 
tax is based on the volume of wort fermented (or of the fermenting vats). The steam is 
passed in at the top by the tube b, and is distributed uniformly over the interior by means 

of a perforated pipe (shown dotted 
at c), the tap, g, at the bottom 
being left open to discharge the 
condensed water. When the whole 
mass is hot, steam begins to issue 
from this tap and drives out all 
the air. The tap is then shut, and 
the pressure, shown by the mano- 
meter, e, soon rises to 3 atmos. 
After about 45 minutes at this 
~^; pressure (temperature 135), the 
conversion is complete. With 
damaged or frozen potatoes, the 
steam is allowed to issue for an 
hour from the tap, g, before raising 
the pressure, and steam is then passed in by the pipe V as well. A pressure higher 
than 3 atmos. turns the mass brown, owing to the caramelisation of the maltose. To 
discharge the apparatus, the pressure is maintained at its maximum and connection 
made with the discharge pipe, i, by opening the valve, h. At the bottom of the cone, 
just above k is a horizontal disc of cutting grids, through which the whole of the mass 
is forced by the steam -pressure and thus converted into a paste ; the pipe i carries 

1 Witte (1904) gives the following improved modification of the Baumert and Bode method for estimating 
the starch in cereals : 1-2 grms. of the meal, sieved and mixed to a paste with water, are heated with 60-70 c.c. 
of water under 4 atmos. pressure (145) in a Lintner bottle or other vessel for two hours in an oil-bath. After 
being allowed to cool partially, the whole is introduced into a flask and boiled for 10 minutes with a few grains 
of zinc. When cool, the liquid is made up to a volume of 500 c.c. and filtered through a thin layer of asbestos. 
To 50 c.c. of the filtrate are added 5 c.c. of 10 per cent, caustic soda solution, about 1 grm. of shredded asbestos 
and 100 c.c. of 96 per cent, alcohol ; the whole is well shaken and then allowed to settle, when the liquid is 
decanted through an asbestos filter-tube (Allihn) ; the deposit is also washed on to the filter with 40 c.c. of 60 per 
cent, alcohol, and is washed successively with 40 c.c. of 60 per cent, alcohol, a mixture of 25 c.c. 96 per cent, alcohol, 
10 c.c. of water, and 5 c.c. of 10 per cent. HC1, a further 40 c.c. of 60 per cent, alcohol, 25 c.c. 96 per cent, alcohol, and 
finally with a little ether. After being well pumped off, the tube with the starch is dried at 120 in a current of 
dry air for twenty minutes, cooled, and weighed. By heating the tube to redness in a current of air the starch is 
burnt away, and its weight, when cool, subtracted from the original weight, leaves that of the starch corresponding 
with 50 c.c. of the solution ; multiplication by 10 gives the amount of starch in the meal originally weighed out. 

When starch is to be determined in materials free from cellulose, dextrin, and other substances which give 
reducing substances (pentoses, &c.) with acids, the following method (Marcker and Morgen) should be used : 
3 grms. of the substance, mixed with 200 c.c. of hot water, are treated with 15 c.c. of hydrochloric acid (sp. gr. 
1-125) for 2J hours in a flask immersed in a boiling water-bath and fitted with a simple reflux tube 1 metre in 
length. The cooled liquid is almost neutralised with caustic soda (it must be left faintly acid) and made up to 
500 c.c., the amount of glucose in 25 c.c. being then determined by means of Fehling's solution (see p. 186). The 
quantity of starch is obtained by multiplying the amount of glucose ^by 0-9. 

For spirit manufacture, where all materials giving fermentable substances are of importance, the new method 
given by Reinke is employed : 3 grms. of the amylaceous material is heated in a Lintner bottle with 30 c.c. of 
water and 25 c.c. of 1 per cent, lactic, acid solution for two hours at 135. The liquid is then cooled to 70-80, 
shaken with 50 c.c. of hot water, cooled to the ordinary temperature, made up to 250 c.c., shaken several times 
during the course of half an hour, and filtered. 200 c.c. of the filtrate are heated with 15 c.c. of hydrochloric 
acid^(sp. gr. 1-125) for two hours in a reflux apparatus immersed in a boiling water-bath. The cooled liquid is 
near/i/,'neutralised and made up to a volume of 500 c.c., 25 c.c. being then titrated with Fehling's solution.^as 
above. 




FIG. 103. 



CONVERTERS 



119 



it to the coolers and then to the wort vessels, where suitable stirrers complete the 
gelatinisation of the mass. 

In order to avoid danger of explosion, the Henze autoclaves should be tested once a 
year to ascertain if they are capable of withstand- 
ing the pressure employed, since they may become 
weakened at rusted parts. 

Maize, rice, and cereals are also treated in the 
Henze apparatus, but with the addition of 110-140 
kilos of water per 100 kilos of cereals, since these 
contain less water (15 per cent.) than potatoes (75 
per cent. ), and without the water the desired fluidity 
of the starch would not be obtained. The volume 
of the autoclave is 350 litres per 100 kilos of maize. 
If a pressure of 5 atmos. cannot be easily attained 
in the autoclave, instead of using the whole grain, 
it is better to crush or grind it coarsely and then 
introduce it into the necessary quantity of boiling 
water in the autoclave. During the boiling, the 
maize should be kept in continual motion by steam- 
jets at the bottom and along the autoclave, or by 
an air-jet at the bottom with an outlet at the top, 
so that a spiral motion is imparted to the mass 
(Fig. 105). Only rarely are mechanical stirrers 
employed inside the autoclave. After an hour's 
heating the pressure reaches 2^ atmos. and is 
raised to 3 atmos. in another hour. The mass is 
then discharged in the usual way. 

Maize that is too dry is steeped in water for a day before boiling. 

Maize always contains a little ready formed sugar (1-7 to 10 per cent.), and this must 
be allowed for in calculating the yield and also in order to avoid a too protracted heating, 




FIG. 104. 





FIG. 105. 



FIG. 106. 



which caramelises the wort and injures it by decomposing the large proportions of fat 
present. 

Saccharification is effected by means of malt (2-5 to 3 percent, on the weight of maize) 
added to the starchy mass at a concentration of about 14 Be. and cooled to about 
50 ; if it is too cold, it coagulates and the diastase acts irregularly ; at 35-40 the lactic 
fermentation readily takes place ; above 65 to 70 the diastase is altered and rendered less 
active, dextrin being then formed in preference to maltose. The paste from the Henze 
autoclave is cooled in various ways, e.g. with Ellenberg's apparatus (Figs. 106 and 107), 
in which it is dropped from the top of a pipe into a vessel similar to the Hollanders 
used in paper factories (see Paper), where it is mixed, cooled, and broken up by a rotating 
drum, T, fitted with knives which graze other knives fixed to an inclined plate, d, at the 



120 



ORGANIC CHEMISTRY 



bottom of the vessel ; the drum makes 200 revolutions per minute ; above the pipe by 
which the paste enters is a Korting injector, e, which produces a strong current of air 
and thus facilitates the cooling of the paste during its fall. 

At the present time preference is given to apparatus with centrifugal stirrers, the 
cooling and ako the saccharification being carried out in these. Fig. 108 shows the 

Hentschel apparatus. The hot starch -paste 
from the Henze converter passes through the 
pipe 6 into the vessel A, where it is cooled 
by water flowing from m to n through an 
internal coil ; the mass is mixed by means of 
a kind of screw, B, rotated by bevel -wheels 
outside the vessel and the air-draught is pro- 
duced by the Korting injector, r. Fig. 109 
shows a section of the Pauksch masher, in 
which the cooling is effected by means of water 
circulating through the jacket, C, surrounding 
the vessel, the liquid being mixed by four 
blades, p, which are rapidly rotated (300 revolutions per minute) by the pulley, S, and, 
as they graze the bottom of the vessel, have also a grinding action. A battery of Henze 
autoclaves is sometimes used in conjunction with one masher. 

Since, during this saccharification, which may last three or four hours (and is complete 
when a test of the liquid, how very fluid, no longer gives the blue starch reaction with 
iodine solution), the mass may become infected with extraneous bacteria, which may 
have a harmful influence during the alcoholic fermentation of the wort, it is usually heated 




FIG. 107. 




FIG. 108. 



FIG. 109. 



for a few minutes at 70-75 to kill these germs. This procedure has, however, the 
disadvantage of destroying the diastase, which can always play a part during the 
fermentation, and of increasing thje quantity of dextrin. 

In the Effront process (see later), the fermentation is carried out in presence of hydro- 
fluoric acid, which kills all the bacteria but not the enzymes (previously acclimatised to 
the hydrofluoric acid), so that the saccharification can be effected at the most favourable 
temperature (55) without subsequently heating to 75. 

As soon as the saccharification is terminated, the wort should be cooled to about 20, 
and the fermentation started. This cooling may be accomplished in the masher, with 
suitable internal coolers (Fig. 108), but it is better done in appropriate apparatus. 

One form of horizontal Hentschel refrigerator is shown in Fig. 111. The horizontal 
rotating axis (40-50 turns per minute) is formed of a tube, to which is fastened a 



FERMENTATION 



121 



deep screw and in which cold water circulates from h to k. The screw moves in a horizontal 
cylinder through which the hot wort is forced by the screw in a direction (b to /) opposite 
to that taken by the water ; the 
temperature of the wort at the 
outlet, /, is controlled by regu- 
lating the flow of wort and 
water, and, if necessary, by spray- 
ing the exterior of the cylin- 
der with water by means of the 
tube I. With 700 c.c. of water, 
.a litre of wort is cooled from 60 
to 16. 

To separate the solid residue, 
husks, &c. (grains), from the wort, 
the latter is filtered cold through 
dehuskers, which have different 
forms, some fixed and some re- 
volving. The most recent Pauksch 
type consists of a kind of centri- 
fuge (hydro-extractor) with a fine 
copper gauze basket, almost like 
the centrifuges used in sugar fac- 
tories (see Sugar). 

Brewers and distillers often 
use also ^ the Hentschel dehusker 
(Fig. 112 and 113), consisting 
simply of a rotating drum, with 
a spiral of metal gauze, which 

carries the drained grains to the middle and discharges it in cakes through doors which 
close automatically ; the liquid flows to the bottom and passes to the fermenting vessels. 




FIG. 110. 




FIG. 111. 



FIG. 112. 



ALCOHOLIC FERMENTATION. Industrially the transformation of saccharine 
worts into alcoholic liquors is always effected by means 
of organised ferments (or yeasts). Worts left exposed 
to the air at 15-30 ferment spontaneously, but, owing 
to the different species of bacteria present, not only 
alcoholic fermentation, but also harmful secondary fer- 
mentations, such as the acetic, lactic, butyric, &c. (the 
corresponding bacteria are shown in Fig. 114), develop. 

Owing to the studies of Rees and more especially of 
Hansen, it is nowadays admitted by everybody that the 
principal agent of alcoholic fermentation is Saccharomyces 
cerevisice (Fig. 115, a, b, and c), a fungus that multiplier; 
by budding and has varying dimensions (2-5-10 p) and 
appearance according as it develops at the surface (Fig- 
116) or in the body of the wort (Fig. 117). In Fig. 118 is represented a cell of the 
ferment magnified 4000 times and showing the granulations, vacuoles, protoplasm, 




FIG. 113. 



122 ORGANIC CHEMISTRY 

cell-wall, &c. In spirit distilleries, a mixture of two varieties of yeast (top- and bottom- 
yeasts) is used, these being of the same race but not interconvertible ; often top-yeast is 
preferred, as it is more active, whilst in lager-beer breweries, where the fermentation 
is slow, bottom-yeast is mostly used. 

The final result of the decomposition of maltose by yeast can be expressed thus : 
Ct2H 22 O u + H 2 = 4C 2 H 5 -OH + 4CO 2 ; 




(a) Acetic bacteria 



FIG. 114. 
(b) Lactic bacteria 



(c) Butyric bacteria 



actually, however, the maltose and dextrin formed from the starch are transformed into 
glucose by the action ,of the maltase contained in the ferment along with the zymase, 
the latter then converting 95 per cent, of the glucose into alcohol and carbon dioxide 






FIG. 115. 

with the development of heat (if the glucose were transformed completely into H 2 + C0 2 , 
the evolution of heat would be seven times as great) : 

C 6 H 12 6 (glucose) = 2C 2 H 5 -OH + 2CO 2 + 33,000 cals. 







FIG. 116. 



FIG. 117. 



A small part of the sugar serves for the growth and multiplication of the 
yeast (Pasteur), about 3 per cent, of it is converted into glycerol, 1 about 
0-5 per cent, into succinic acid, and the remainder into higher alcohols forming 
fusel oil, this consisting mostly of amyl alcohol (C 5 H n -OH,- isobutylcarbinol) , 
with small proportions of isopropyl alcohol, butyl alcohols, and esters. Ehrlich 

1 The formation of glycerol during fermentation has not yet been explained ; it is thought that it forms a 
direct secondary product from the decomposition of the sugar into alcohol and CO 2 , or that it results from the 
action of lipase on the fats and oils of the ferment cells ; Buchner (1906) holds that it is formed from the sugar 
but by a special process ; Reisch (1907), however, finds no relation between the amounts of alcohol and glycerol 
formed and hence regards it not as a product of fermentation, but rather as a metabolic product of the yeast. 



YEAST 



123 



(1909) has shown, however, that fusel oil and succinic acid are formed by the 
decomposition of the amino-acids which constitute the cells of the ferment. 
The theoretical yields of pure alcohol from various sugars are as follow : 

100 grms. of saccharose C 12 H 22 U 51-11 grms. or 64-6 c.c. of alcohol 
,, maltose C 12 H 22 O n 51-11 ,, 64-6 ,, 
starch (C 6 H 10 5 ), 56-80 71-8 
., glucose C 6 H 12 6 48-67 61-6 

Various sugars, however, do not ferment directly (saccharose, lactose, &c.), 
but must first be inverted, that is, transformed into hexoses (fermentable 
sugars with six carbon atoms), but ordinary alcoholic ferments (saccharo- 
mycetes) contain the inverting enzymes (besides zymase) and hence can effect 
inversion and then fermentation. 1 

The fermentation industries in general, and the alcohol industry in particular, have 
made marked progress since the introduction of pure ferments. The cultivation of pure 





FIG. 119. 





FIG. 118. 



FIG. 120. 



FIG. 121. 



ferments has at the present time become a special industry of great importance ; all 
precautions are taken to select and cultivate well-defined races of ferments, and this is 
especially owing to Hansen of Copenhagen, who, by thirty years of study and experiment, 
showed the great practical value of the selection of yeasts. The first pure culture is 
made in a moist chamber of glass, c (Fig. 119), fixed on a microscope slide, a ; the whole 
is sterilised, either by a flame or by heating for two hours in an oven at 150. Sterilised 
water is placed on the bottom of the chamber to keep the atmosphere moist, and the 
chamber placed in an incubator at 30 to 35. The bacterial culture is developed in a drop 
of gelatine, b, adhering to the lower side of the cover -glass covering the chamber. 

The culture of pure ferments can also be carried out in Chamberland flasks of 30 c.c. 
capacity (Fig. 120), half filled with nutrient gelatine and fermentable substances, and 
covered with a glass cap full of sterilised cotton-wool. 

The more or less pure ferment which it is desired to cultivate is introduced by means 
of a sterile platinum wire into a flask containing sterile water, which is well mixed and 
should become just turbid. A drop of this water is then examined under the microscope 
in order to ascertain the number of cells of the ferment it contains. By means of a 
platinum wire sterilised in a flame, a drop of the water is introduced into a Chamberland 

1 According to Boysen-Jensen (1909) the zymaae of alcoholic ferments is constituted of two enzymes : deztrase 
and dihydroxyacetonase, glucose first forming 2 mols. of dihydroxyacetone OH CH 2 - CO CH,- OH (triose), which to a 
small extent can be fixed in the form of oxime or hydrazone (which see) by means of hydroxylamine hydrochloride 
or methylphenylhydrazine acetate ; the dihydroxyacetonase then decomposing the dihydroxyacetone into 2CO 2 
and 2C 2 H 6 OH. The dextrase alone would give directly alcohol and CO 2 if glycerol were added to the solution 
of glucose. With zymase (which contains dihydroxyacetonase), pure dihydroxyacetone gives alcohol and CO 2 , 
whilst with oxydase it gives only CO,. 



124 



ORGANIC CHEMISTRY 



flask containing liquefied gelatine at 35. After the latter has been well shaken, a drop 
of the gelatine is examined microscopically on a glass micrometer (marked with crossed 
lines) to see that there are not too many rr too few cells present, since the colonies that 
ultimately develop from the single cells should develop sufficiently far apart from one 
another not to mingle. Of this inoculated gelatine, one or more drops are placed on the 
cover-glass of the moist chamber, this being kept under a bell-jar until the gelatine has 
solidified and then placed, upside down, in the chamber. In a thermostat at 25, the 
ferments are usually sufficiently developed after two or three days and the various colonies 
are then examined under the microscope to ascertain if one or more of them are pure, 
that is, constituted of similar cells of one and the same ferment. Each of the pure colonies 
is touched separately with a small piece of sterilised platinum wire, which is immediately 
dropped into a Pasteur flask (125 c.c.) charged to the extent of two-thirds with gelatine 
and nutritive substances (Fig. 121), the rubber tube being momentarily removed. The 
flask is at once closed again, and is then kept in a thermostat at 25 to 28. After 2 days 

the liquid will be in a state of active 
fermentation, a large quantity of the 
ferment having been formed. Each 
of these flasks represents a pure 
culture (provided that the proper 
precautions have been taken in the 
inoculation). All the cultures are, 
however, examined, one or two drops 
from each flask being observed under 
the microscope. 

These pure yeasts or other pure 
ferments are largely used by brewers 
or distillers, who have ferments 
suited to then- needs selected and 
preserved by scientific institutions, 
from which cultures in Pasteur 
flasks are despatched to them when 
FIG. 122. the organisms in their own ferment- 

ing vessels begin to degenerate or 

become contaminated. In Fig. 122 is shown diagrammatically an apparatus for 
the industrial preparation of selected ferments ; the metal reservoir, C, provided 
with a safety-valve, q, and a manometer, r, is filled, by means of the pump, u, 
with air filtered through a cotton-wool filter, t, and compressed under a pressure 
of 3 to 4 atmos. The vessel, A, is first sterilised with steam under pressure, which 
enters at the tap, /, whilst the air is driven out through the tube, b, dipping into a 
vessel of mercury forming a seal. When the cock, /, is shut, g is opened so as to 
allow air to filter through d into A. Hot wort is introduced into the reservoir, A, 
heated to boiling and then cooled by means of a water-spray issuing from an annular 
tube, e, and bathing the outside of A. The fermenting vessel, B, which is sterilised in the 
same way as A, is also furnished with a cotton -wool filter, h, and a hydraulically sealed 
tube, ip, through which the C0 2 is to escape ; the glass tube, O, which is a continua- 
tion of the filter, indicates the level of the liquid inside the vessel. It is further provided 
with a vertical stirrer which is set in motion by the handle, k, and serves to mix the wort 
and yeast which are introduced through the small tap, I. A slight air-pressure is main- 
tained in both A and B in order to prevent external contaminated air from entering 
either when the discharge-cock, m, for the fermented wort is opened or through any leaks 
there may be in the apparatus. In this way B can be used for a year or more without 
contamination taking place, a little residual yeast being left after each operation to ferment 
the succeeding charge of wort. The sterile wort, cooled to 15, is passed from A into 
B by means of the tube, a n, and before it reaches the level of the tap, I, the pure yeast 
contained in a Pasteur flask is introduced through this tap ; B is filled to the extent of 
about three-fourths (about 200 litres) with the wort from A, the whole being then well 
mixed. When the fermentation is ended (in three or four days with worts for alcohol 
production, or in 8 to 10 days for beer worts), the yeast is allowed to deposit ; the 
fermented wort is discharged from m by increasing the pressure of the air and, when it 




CULTIVATION OF PURE YEAST 125 

begins to issue turbid (owing to suspended j east), m is closed and about 30 litres of wort 
introduced from A and well mixed in, 30 litres of the turbid yeasty liquid being then 
run off from B, this amount being sufficient to induce fermentation in 40 hectols. of 
wort in the ordinary fermenting vessels ; a further quantity of 30 litres of wort is then 
run in from A and, after mixing, another 30 litres of yeasty wort drawn off. That 
remaining in B serves for the next operation. This is the procedure adopted in large 
breweries and distilleries ; whilst in yeast-factories the wort is prepared from barley 
and rye under the action of malt for an hour at 60 and for about 24 hours at 40 to 
44 in order to produce about 1 per cent, of lactic acid, which peptonises the proteins 
and so affords better nutriment for the yeast, the action being completed by the addition 
of 10 grms. of sodium or ammonium phosphate per hectolitre of wort. The wort is then 
fermented as above at 18 to 20, 
and the yeast, which is formed in 
large quantity, is washed with water 
by decantation, freed from excess of 
water in centrifuges or filter-presses 
and made into a paste with 5 to 10 
per cent, of potato -starch, forming 
cakes which are sold under the 
name of pressed yeast at about 
3 12s. per quintal (220 lb.). 100 
kilos of rye yield 16 kilos of yeast. 
In Germany more than 210,000 
quintals of pressed yeast are pro- 
duced annually, and 10,000 to 
13,000 quintals exported; in five 
factories alone more than 110,000 
quintals were made in 1909. In 
Italy, 1361 quintals were imported 
in 1905 ; 2000 in 1906 ; 3500 in 1907 ; 
4500 in 1908; in 1909, 5300_ quin- 
tals, of the total value of 21,700 
(including 2000 quintals of diamalt 
or liquid malt worth 10,700) ; and 
in 1910, 4750 quintals, including 
1137 of diamalt. Certain of the 
French factories export as much as 
30 or 40 quintals of pressed yeast per 
day. In Austria, the law of May 18, 
1910, regulates the trade in yeast so as to prevent adulteration and mixture. 1 In France 
and latterly in Italy, industrial spirit distillers are making use of the Jacquemin apparatus 
(Fig. 123) for the preparation of pure yeast cultures. The peptonised wort is prepared 
as described above, and the sterilised air, compressed by the pump A, passes through a 
filter of cotton-wool moistened with mercuric chloride, F, into a battery of vessels, G, tho 
first and third of which are empty, whilst S contains sulphuric acid and n soda solution ; 

1 Yeast Manufacture. Not only in Austria, but also in Germany, the yeast industry has lately assumed 
great importance, especially in spirit factories. It has given rise to special legislation and has led to the 
formation of powerful syndicates to regulate prices and production. The largest consumers are the bakers. 

At one time, with a yield of 30 to 32 per cent, of alcohol on the weight of cereal used, the amount 
of yeast obtained was 12 to 14 per cent. During recent years a marked increase has been effected in the quantity 
of yeast (up to 20 per cent.), the yield of alcohol being diminished by vigorous aeration of the wort during fer- 
mentation (30 to 40 cu. metres of air per hour for every 100 kilos of cereals converted into wort). By the new 
Braasch process the yield of yeast can be raised to 40 per cent, and that of alcohol lowered to 15 per cent, (under 
some conditions of the market the production of yeast is more remunerative than that of alcohol). The value 
of yeast in Germany is calculated at about 3 16*. to 4 per quintal, and some factories produce as much as 
5000 to 10,000 quintals per annum ; the alcohol is valued at 1 8. per hectolitre. 

In the old Vienna process, worts of 10 to 20 Balling (or even heavier) were fermented by means of yeasts pre- 
pared with worts rich in lactic acid (100 c.c. of this wort should require 12 to 14 c.c. of normal sodium hydroxide 
solution for neutralisation). When the fermentation was complete, the yeast was collected by means of ladles 
and despatched along channels into vats, where its activity was arrested with cold water. After this, it was 
shaken on silk sieves, which retained all the husks or grains ; the yeast passing through the sieves was washed 
two or three times with water and, after settling, pressed into cakes. In 1887-1890 all yeast factories worked 
on this plan, but nowadays only few of them do so. 

The new aeration process starts from clear wort and green malt (non-kilned). The cereals for preparing the 




FIG. 123. 

Vapeur, steam; eau, water; laveurs d'air, air-washers; 
filtre a air, air-fllter 



126 ORGANIC CHEMISTRY 

the empty vessels serve as safeguards, in case the liquids are sucked backwards. The 
air sterilised in this way passes along suitable pipes to all the ^fermenting vessels, 
B, B', G, C', D. B is two-thirds filled with the peptonised wort (20 to 30 litres), which is 
boiled for a few minutes by steam entering through b and then cooled by passing a vigorous 
current of air through the wort and by an annular spray of water applied to the outside 
of the vessel B by the tube e. When the temperature has fallen to 20, the contents 
of a Pasteur flask of pure yeast are introduced through the tube a, and the fermentation 
allowed to proceed for 24 hours ; in the meantime, wort sterilised and cooled to 20 is 
prepared in B' ; a little of the yeast is then passed from B through the tube t to B', 
the remainder being discharged, by the three-way cock, t, into the larger vessel, C, which 
contains sterilised wort (250 to 300 litres). When the fermentation has reached an 
advanced stage (a definite attenuation ; see later), the wort is discharged through the tube r 
into D, which also contains sterilised wort, and that remaining on the bottom of C is 
forced by compressed air into the vessel C', previously charged with sterile wort. 

It will be seen that, by this procedure, the working is continuous, and the yeast is 
renewed only once .or twice per month. The yeast may then be separated from D and 
pressed, or the actively fermenting wort (5 to 6 hectols.) may be used to induce fermenta- 
tion in the factory vats containing ordinary wort. 

The selected yeasts are controlled practically, by measuring then- fermentative activity 
and by determining the concentration with the microscope and cell -counters, note being 
taken of extraneous organisms. 

Pressed yeast in cakes keeps for several days if well wrapped in paper and placed in 
tightly closed boxes in a cool room ; otherwise it soon becomes covered with mould and 
unusable. When the stock of yeast is larger than is required, it can be dried at a cost 
of a shilling per quintal and sold as a good cattle food. To prevent secondary fermenta- 
tions from taking place, instead of the lactic acid fermentation, during the preparation 
of selected yeasts, Bucheler (Ger. Pat. 123,437) suggests the addition of 180 c.c. of 
concentrated sulphuric acid to every hectolitre of wort ; the process yields excellent 
results in practice, notwithstanding the disputing of the patent from 1900 to 1909, owing 
to the fact that a similar patent (No. 3885) was granted in Austria to Bauer in 1900. 

FACTORS WHICH FACILITATE OR RETARD FERMENTATION. Alcoholic 
fermentation may be hindered by various factors. Very concentrated sugar solutions 
do not ferment, whilst with a concentration of 70 per cent., only 6 per cent, of the sugar 
is converted into alcohol ; with a strength of 60 per cent., 25 per cent, is transformed, 
and when the concentration is 30 per cent, it is possible, although not without difficulty, 
to convert 92 per cent, of the sugar into alcohol. 

Temperature has also a very marked influence on alcoholic fermentation, and at 
or at 60 it ceases completely ; later we shall see at what temperature the process takes 
place most regularly from the point of view of the industrial yield. 

Alcohol, although a product of fermentation, when it reaches a certain concentration, 
may prevent further fermentation. And this an ti -fermentative action of the alcohols is, 
to some extent, proportional to their molecular weights. Thus the fermentation of 
glucose can be arrested by 20 per cent, of methyl alcohol, 16 per cent, of ethyl alcohol, 
10 per cent, of propyl alcohol, 2-5 per cent, of butyl alcohol, 1 per cent, of amyl alcohol, 
and 0-1 per cent, of capryl alcohol. 

mash and then the wort are no longer ground, but are softened with water and then crushed. The mashing of 
the green malt is carried out in a medium slightly acidified with sulphuric acid, the lactic ferment (Bacillus 
Delbriickii) being allowed to act, after the diastase, for several hours at 40 to 50. When the desired acidity is 
reached, further acidification is prevented by heating the whole mass to 68 to 70 (the total amount of sulphuric 
and lactic acids, without CO 2 , corresponds with 5 c.c. of normal NaOH per 100 c.c. of wort). The concentration 
of the wort used was at one time 12 to 14 Balling, but at the present time 10 Balling is preferred. The tempera- 
ture of fermentation is about 25. If the acidity of the wort is less than 2 c.c. of normal soda per 100 c.c., the 
yeast obtained is flocculent and separates badly. The separation of the yeast is now effected thoroughly and 
rapidly in centrifuges. The fermentation is started by adding to the wort 4 to 5 per cent, of yeast (calculated on the 
weight of cereals used) and is finished in 10 to 12 hours ; the yield of 40 per cent, (on the weight of cereals) of 
yeast is in addition to the amount added (5 per cent.). The yeast culture's should be renewed occasionally. 

The fermented wort is feebly alcoholic (less than 1 per cent, of alcohol), so that the distillation and rectifica- 
tion necessary to obtain 90 to 95 per cent, alcohol are very expensive ; further, the alcohol is not of good quality 
and is hence only suitable for denaturing. The diminished yield of alcohol is due partly to loss of the alcohol 
carried away by the large volumes of air passed through the wort and partly to destruction of maltose by ferments 
or enzymes developing in presence of excess of air. The less the amount of air used, the greater is the amount 
of spirit obtained. 

In the control of the purity of the yeast, account must be taken of the extraneous ferments, of the quantity 
of starchy substances (when starch is not added this does not reach 4 per cent.) and of the fermentative activity. 



ANTISEPTICS AND FERMENTATION 127 

ANTISEPTICS, in general, prevent fermentation when they are present in relatively 
great concentrations ; they may, if their dilution is great, exert a favourable influence 
on fermentation. 1 

However, since the favourable action exhibited by these solutions depends on the 
quantity of yeast present and that of the antiseptic dissolved, it is possible, when the 
quantity of yeast is large, that solutions more concentrated than those indicated in 
column (B) may produce favourable effects on the fermentation. It is unnecessary to 
state that these concentrations vary somewhat with the nature of the organisms. It 
has been shown recently (1910), for example, that Staphylococcus pyogenes aureus resists 
a 2-7 per cent, solution of mercuric chloride for six hours. 

The organic acids also exert an unfavourable influence on alcoholic fermentation, 2 
whilst, within certain limits, lactic and formic acids and formaldehyde have a beneficial 
action, since they prevent the development of harmful bacteria and are readily tolerated 
by alcoholic ferments specially acclimatised to their action. By adding small quantities 
of formaldehyde and of sterilised milk (which then gives lactic acid), the yield of 
alcohol has recently been increased by as much as 2 per cent. E. Soncini (1910) has 
shown that the course of fermentation in general is closely connected with the chemical 
medium in which it takes place ; thus, in a saccharine wort (from bananas), the lactic 
fermentation first develops spontaneously and proceeds until the lactic acidity reaches a 
certain limiting amount ; this may be followed by alcoholic fermentation, which, in its 
turn, may be succeeded by the acetic fermentation ; the lactic fermentation may ulti- 
mately begin again. It is only by considering all these conditions that a regular alcoholic 
fermentation and a good yield of pure alcohol can be assured, since in general the secondary 
and harmful products of the fermentation (higher alcohols, such as amyl, &c.) result 
from the actions of extraneous micro-organisms. The carbon dioxide formed during 
fermentation may give rise to pressures as high as 12 atmos. if hermetically sealed vessels 
are used, and the action of the yeast is then retarded or even arrested. 

PRACTICE OF FERMENTATION. To start the fermentation of the worts pre- 
pared as described above, various methods are used : in some cases a portion of old, 
fermented wort from a preceding operation is employed ; but this is not a rational method, 
because the yeast in the old wort is in a condition unfavourable to development and is 
also contaminated with other micro-organisms which would develop readily in the new 
wort. To be preferred is the custom followed by certain distilleries of starting the fer- 
mentation with brewery yeast, which is cheap and comparatively pure. The best and 
most rational method is, however, the use of selected yeast in culture wort or in a pressed 
condition (see above), as supplied by various firms and institutions which guarantee its 
purity. By this means alone it has been possible during the past few years to increase 
the mean yield of alcohol in distilleries by 0-5 per cent, or even 1 per cent., and at the 
same time to improve the quality of the product. 

It is advisable to ferment worts as soon as they are prepared and cooled to 15 to 20, 
delay resulting in contamination with heterogeneous germs always present in the air. 

To avoid secondary fermentations as far as is possible, addition is often made to the 

Thus, lor example : 



Bromine 
Thymol 
Salicylic acid 
Phenol 

Sulphuric acid 
Boric acid 



2 The action of some of the commoner acids is as follows : 



(A) The most dilute solution (B) The most concentrated 


capable of preventing solution capable of 


fermentation is : favouring fermentation is ;. 


oride . 




1 in 20,000 


1 in 300,000 


ermanganate 






10,000 




100,000 












4,000 




50,000 












3,000 




20,000 


d 










1,000 




6,000 












200 




1,000 


:id 










100 




10,000 




25 




8,000 





Dose that retards 


Dose that arrests 




alcoholic fermentation 


alcoholic fermentation 


Acetic acid 


0-50 % 


1-0 % 


Formic 


0-20 % 


0-30 % 


Propionic acid 
Valeric ,, 


0-15 % 
0-10 % 


0-30 % 
0-15 % 


Butyric ,, 


0-05 % 


0-10% 


Caproic 





, 0-05 % 



128 ORGANIC CHEMISTRY 

wort of antiseptics, to which the selected yeasts have been habituated. Thus, small 
proportions, of calcium bisulphite or, better, of ammonium or aluminium fluoride are 
added, the 'hydro fluoric acid liberated under the action of the acids formed in the 
secondary fermentations killing the harmful organisms. With the Effront process, 
hydrofluoric acid (see vol. i, p. 156) is added directly in the proportion of 5 or even 10 grms. 
per hectolitre of wort (some yeasts resist as much as 100 grms. of HF per hectolitre). 
Sometimes a selected lactic ferment (Bacillus acidificans longissimus) is added, this ako 
favouring the production of pure alcohol. 

The use of these yeasts acclimatised to the action of hydrofluoric acid renders possible 
the employment of the temperature 55 to 57 (see above) for the previous saccharification 
of the starch by diastase, this low temperature resulting in the formation of an increased 
amount of maltose ; also if there are other noxious living micro-organisms in the wort, 
these are killed by the hydrofluoric acid during the fermentation. 

Effront, however, succeeded in preparing yeasts capable of fermenting also the dextrin 
with ease ; when these are used, the saccharification with diastase can be effected with 
less malt and at 64 to 65, so that harmful micro-organisms are killed. All the apparatus, 
instruments, and vats which come into contact with the wort should be previously washed 
with dilute hydrofluoric acid solution (100 grms. per 25 litres of water). 

For every hectolitre of wort are added about 30 grms. of pressed yeast in small quantities 
mixed up with increasing quantities of wort and well stirred in ; the fermentation then 
starts immediately. 

The fermentation of the wort proceeds in three successive phases : 

(1) Preliminary fermentation, in which the yeast develops and grows, 
the most favourable temperature being 17 to 21. 

(2) Principal fermentation, in which the maltose and glucose are fermented, 
best at 26 to 30. 

(3) Secondary fermentation, in which the dextrins are fermented, the 
diastase continuing to saccharify the remaining dextrins as the wort becomes 
warm, the best temperature being 25 to 27. 

The vats, holding 10 to 90 hectols. and often furnished with stirrers, are filled with 
wort to the extent of nine-tenths. The temperature is regulated by suitable cold-water 

coils (attemperators, Fig. 124), which 
are of various forms (see Beer). In 
general, these attemperators have a 
surface of 0-3 to 0-4 sq. metres per 
10 hectols. of wort. Fermentation is 
begun in the vats at 12 to 15, and 
after 2 or 3 hours the tempera tuie 
FIG 124 rises and the fermentation becomes 

vigorous. The liquid is then agitated 

to liberate the CO 2 , thus diminishing the pressure in the mass and facilitating the 
fermentation, the temperature not being allowed to exceed 28 to 29. After two days, 
the principal fermentation ceases and the temperature is maintained at 25 to 26 for a 
day, the fermentation being thus completed. 

Worts that are too dilute or are made from poor malt or impure grain give a boiling 
fermentation that hurls the liquid from the vat and renders the subsequent distillation 
difficult. This inconvenience is avoided by using more concentrated worts and good 
yeast, or, in case of necessity, adding 100 to 200 c.c. of oil to each vat. 

Ammonium fluoride (2 to 2-5 grms. per hectolitre) or hydrofluoric acid (rather less) is 
often added to the wort before fermentation. 

LOSSES AND YIELDS. A residue of unfermented starch (0-7 to 2 per cent.) and 
dextrin (5 to 8 per cent.) always remains after fermentation. In every fermentation 2 to 
3 per cent, of glycerol are formed ; also part of the sugar serves as food for the yeast and 
part of the alcohol evaporates, this making a total of 6 to 8 per cent. 

Starting with 100 parts of starch, 12 to 20 parts are usually lost in various ways, and 
with improper working the loss may reach 28 per cent. 

If the starch could be transformed theoretically into alcohol and carbon dioxide alone, 
100 kilos of starch should yield 71-6 litres of pure alcohol ; allowing for these losses and 




DEGREE OF ATTENUATION 129 

working under the best conditions, 63-5 litres of alcohol are obtained ; 60 litres is a good 
yield and 58 litres a medium one, whilst 55 litres would indicate bad conditions of working. 
The mean starch -contents of many of the prime materials used in the distillery are given 
on p. 117 ; that of green malt (from good barley) is 38 to 42 per cent, and that of kilned 
malt, 65 to 70 per cent. Whilst in 1883 Italian distilleries gave an average yield of 31-5 litres 
of alcohol per quintal of maize, in the season of 1904-1905 the yield (official statistics) 
amounted to 35 litres. 

For calculating the yield, the exact analyses of the prime materials, starch and sugar, 
must be known. The sugar-content of a wort is determined from the density by means 
of the Balling saccharometer modified by Brix, degrees Brix (or Balling) read at 20 
(formerly 17-5) indicating directly the percentage of sugar in the solution. In worts, 
however, part of this density is due to unfermentable substances. 

As fermentation proceeds, the proportion of alcohol increases and the density 
diminishes ; this diminution is called the degree of fermentation or attenuation. The 
density is measured before, during, and after the fermentation on the filtered wort, and 
if it filters badly it is diluted with a definite volume of water. 1 When the fermentation 
is finished and the degree of attenuation controlled, the resultant fermented wash (with 
about 9 to 11 per cent, of alcohol) is subjected to distillation and rectification in order to 
extract the alcohol and separate it from the water, yeast, and other solid and liquid 
substances. Before the distillation apparatus is described, certain special eaccharification 
and fermentation processes, which have been recently applied practically, will be considered. 

The AMYLO PROCESS (Collette or Boidin Process). This process is based on investi- 
gations of Calmette, Collette, Boidin, and others, who found that certain Mucors (mould?, 
see p. Ill), isolated from impure Chinese and Japanese ferments, are capable of performing 
the functions of both diastase and zymase, that is, of transforming starch into alcohol by 

1 The density, p, before fermentation is due to x parts of sugars + z parts of non-fermentable substances ; 
if the density after fermentation indicates the magnitude, z, then p z = x. But this does not give the absolute 
attenuation, since z is altered by the presence of alcohol and carbon dioxide. If the carbon dioxide is eliminated 
by shaking and gentle heating, a density, m, is obtained and the magnitude of (p m) gives the so-called apparer.t 
attenuation (apparent because alcohol is still present) ; the amount of alcohol formed can be allowed for by meai.s 
of a factor, a, the real attenuation being given by A = a (p m). The value of a is determined by distilling a small 

^ 
quantity of fermenting wort, and calculating the value of the expression a = -. : ; a is, however, not a 

constant, but varies with the nature of the sugars, with the original concentration, p, and with the stage of 
the fermentation (incipient, vigorous, or secondary). If a is known, the quantity of alcohol obtainable from a 
fermented wort of a given density can be calculated. 

The ratio between the apparent attenuation, (p m), and the original saccharometer reading, p, gives the 
so-called degree of apparent fermentation (B). If p = 25 and the density (m) of the fermented wort is 3, we have 

25 3 
B = = 0-880, which is the degree of apparent fermentation and indicates that, of every unit of saccharine 

4t> 

substances, 0-880 parts have disappeared, i.e. have been fermented. From the degree of apparent fermentation 
(B), the degree of apparent attenuation can, of course, be obtained : thus, = B gives p m = Bp ; and 

from the factor a mentioned above, the amount of alcohol resulting from such degree of apparent fermentation 
is known. 

The real attenuation (A') is determined by distilling a certain quantity of the fermented wort until its volume 
is reduced to one-third, the residue being made up to the original volume with water and the density, n, measured ; 
the real attenuation then = p n. But, since the residue always contains unfermented matter, in order to 
calculate the alcohol, a factor, b, is determined in the same way as the factor, a, i.e. by distillation of a part of 
the fermented wort ; the quantity of alcohol can then always be determined from the density of the fermented 

wort, for, since A' = (p n) b, b = . Similarly, the degree of real fermentation will be B' = -which 

p n p 

expresses the fraction of the extract (dissolved substance without alcohol) really fermented, the manufacturer 
being thereby able to judge if the fermentation proceeds normally and to establish comparisons with previous 
fermentations, &c. 

The apparent attenuation (alcohol being present) is always greater than the real (derived after elimination 
of the alcohol) and the attenuation difference, D, is obtained by subtracting one from the other, (p m) (p n) = D- 
This magnitude,!), is therefore equal to n mand increases as the fermentation proceeds towards completion; also 
here the quantity of alcohol already formed is found by determining experimentally a factor, c, in the usual way, 

A p m 
so that ^_ = c, or A = (n m).c. The ratio of the apparent to the real attenuation, n = q, gives a quo- 

tient of attenuation which varies with the concentration of the liquid but becomes constant towards the end of 
the fermentation and shows how much the apparent fermentation is greater than the real ; by its means, almost 

all the saccharometric calculations can be made : ~ = the alcohol factor for the real attenuation, and if this is 

q 
divided by q diminished by unity [i.e. by (q 1)], the factor, c, for the difference of attenuation is obtained 

D 

The factor, r, is used for the analysis of liquids for which the value of p is unknown also = B' (degreeof real 

fermentation). 

The following illustrates a practical calculation : the original saccharometric degree of a wort was p = 16-2, 
and that after fermentation m = 1, and that after boiling n = 3-9 ; applying any one of the three factors (a, 
II 9 



130 



ORGANIC CHEMISTRY 



way of maltose and dextrin. Of these moulds, Amylomyces Rouxii, discovered by Calmette 
in 1892, and the Mucors B and C discovered by Collette, Boidin, and Mousain, are of most 
importance industrially. 1 Of the first two, the forms observed under the microscope 
in different stages of development are shown in Fig. 125 (A, B, C, D, and E). 

b, and c) given in the appended Table, the apparent attenuation becomes A = (p m) a (where p = 16-2, 
a = 0-4267) = 6-4858 per cent, of alcohol. Calculating according to the real attenuation, A = (p n) b (where 
p 16-2, n = 3-9, and 6 = 0-5274) = 6-4870 per cent, of alcohol. Lastly, calculating from the attenuation 
difference, D, A (n m) c (where c = 2-2350) = 6-4815 per cent. Hence the fermented wash consists of 
6-48 per cent, of alcohol, 3-9 per cent, of unfermented extract (n), and 89-62 per cent, of water. 

TABLE FOB, CALCULATING THE ATTENUATION IN FERMENTED WORTS 





Alcohol factors for 








Saccharo- 
meter degrees 
of the wort 


the attenuation 


Factors for the 
attenuation 
difference 


Attenuation 
quotient 


c 
Values of r 








Apparent 


Real 






b 


P 


a 


b 


c 


9 




6 . 


0-4073 


0-4993 


2-2096 


1-226 


4-4247 


7 . 


0-4091 


0-5020 


2-2116 


1-227 


4-4052 


8 . 


0-4110 


0-5047 


2-2137 


1-228 


4-3859 


9 . 


0-4129 


0-5074 


2-2160 


1-229 


4-3668 


10 . 


0-4148 


0-5102 


2-2184 


1-230 


4-3478 


11 . 


0-4167 


0-5130 


2-2209 


1-231 


4-3289 


12 . 


0-4187 


0-5158 


2-2234 


1-232 


4-3103 


13 . 


0-4206 


0-5187 


2-2262 


1-233 


4-2918 


14 . 


0-4226 


0-5215 


2-2290 


1-234 


4-2734 


15 . 


0-4246 


0-5245 


2-2319 


1-235 


4-2553 


16 . 


0-4267 


0-5274 


2-2350 


1-236 


4-2372 


17 . 


0-4288 


0-5304 


2-2381 


1-237 


4-2194 


18 . 


0-4309 


0-5334 


2-2414 


1-238 


4-2016 


19 . 


0-4330 


0-5365 


1M!U,S 


1-239 


4-1840 


20 . 


0-4351 


0-5396 


2-2483 


1-240 


4-1660 


21 . 


0-4373 


0-5427 


2-2519 


1-241 


4-1493 


22 . 


0-4395 


0-5458 


2-2557 


1-242 


4-1322 


23 -. 


0-4417 


0-5490 


2-2595 


1-243 


4-1152 


24 . 


0-4439 


0-5523 


2-2636 


1-244 


4-0983 


25 . 


0-4462 


0-5555 


2-2677 


1-245 


4-0816 


26 . 


0-4485 


0-5589 


2-2719 


1-246 


4-0650 


27 . 


0-4508 


0-5622 


2-2763 


1-247 


4-0485 


28 . 


0-4532 


0-5636 


2-2808 


1-248 


4-0322 


29 . 


0-4556 


0-5690 


2-2854 


1-249 


4-0160 


30 . 


0-4580 


0-5725 


2-2902 


1-250 


4-0000 



B. Wagner, F. Schultze, and J. Rub (1908) suggest the Zeiss immersion refractometer as a means of deter- 
mining the attenuation : exact results are obtained rapidly and with a small quantity of liquid (20 to 30 c.c.). A 
little of the wort is well shaken to get rid of carbon dioxide, and filtered through a covered filter, 5 c.c. of the 
filtrate being used to determine the refractometer reading, A, at a temperature of 17-5 ; a further 20 c.c. are 
evaporated to one-half the volume in a porcelain dish to expel the alcohol, the volume being then made up exactly 
to 20 c.c. with water and the refractometer reading, B, taken. From the difference, AB=C, 15 (the refracto- 
meter reading for water) is subtracted, giving E ; the corresponding alcohol degree (by volume), V, is then found 
in the following Table and can be subsequently corrected for the density of the wort : 



E: 

V : 



16-2 17-5 18-8 20-1 21-4 22-8 24-2 25-6 27-1 28-6 30-1 31-7 33-3 34-9 36-4 38-0 
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 



1 Among the Ilyphomyceles (moulds, p. Ill) in the Mucor and Mucedirue Pasteur found certain varieties 
(Mucor racenwsm) capable of transforming sugar into alcohol and carbon dioxide when they live immersed in 
the liquid out of contact of air (like the yeasts) ; in presence of air, they convert the sugar directly into water 
and carbon dioxide. These are called facultative anaerobic organisms. In 1887 Gayon studied other varieties 
which behave similarly (Mucor alternant, spinosus, and cirrinettoides), and Prinsen Geerligs investigated Chlamy- 
domucor oryzce, which is used in Java to ferment molasses. In 1892 Calrnette imported from China, studied, 
and named Amylomyces Rouxii, the Mucor isolated from the rice-ferment used by the Chinese (which is more 
active than the Japanese l-oji) for the preparation of spirit ; later he found this Mucor in rice-husks. At Tokyo 
in 1894, Takamine studied, and applied practically to the saccharification of rice, Aspergillus oryzce (separated 
from Japanese koji, which is a mixture of yeasts and moulds used in Japan for producing alcoholic fermentation), 
but it did not meet with success, owing to its action being too energetic. Boidin, Collette, and Mousain investi- 
gated Mucor /3, which is another Mucor separated from Japanese koji and is different from, and more important 
industrially than, that of Takamine ; Mucor y, which was separated at the same time from Tonkin rice, is of 
still greater practical value than Mucor /s. 

These moulds have the special property of saccharifying starch and of fermenting the sugar thus formed. Their 
saccharifying and fermentative activity is, however, influenced by the acids that they produce. Thus, Amylomyces 
Rouxii, which was the first to be used in practice in 1898, was abandoned later, as it transforms rather too 
much sugar into carbon dioxide and water and, owing to the production of 1-45 grms. of acid per litre of wort (at 



AMYLO PROCESS 



131 



Collette and Boidin patented in 1897 (Eng. Pat. 19,858) a process for the industrial 
utilisation of Amylomyces Rouxii for manufacturing alcohol directly from the starch of 
cereals, &c., and later they utilised Mucor ft. At the present time this process is employed 
on an enormous scale in varioiis distilleries in France, Belgium, and Italy (at Savona). 

As it is necessary to work with perfectly aseptic worts, the starch-paste prepared in 
the ordinary way with the Henze apparatus is passed into closed metal cylinders holding 
200 to 1000 hectols. and furnished with vertical stirrers. When the temperature reaches 
65, 1 per cent, of malt (on the amount of maize used) is added to render the mass rather 
more liquid ; after an hour the mash is slightly acidified by the addition of 0-1 grm. of 
sulphuric acid per litre, and is then rendered completely sterile by passing steam in at 
the bottom and boiling the wort until the steam issues freely from the upper aperture. 
The apparatus is then closed hermetically, a vacuum being produced by the condensation 




FIG. 125. 

A. Colonies of Amylomyces Rouxii in wort-gelatine. B. Mycelial conidia of Amylomyces Rouxii 
in aerobic cultures. C. Segmentation into gemmae of the mycelium of Amylomyces in anaerobic 
culture. D. Hyphse of Mucor /3 (1 : 100) with sporangia in aerobic culture. E. Mycelium of 
Mucor with spores in different stages of development in anaerobic culture : 1, spores just sepa- 
rated ; 2, turgid spores ready to germinate ; 3, germinating spores ; 4, mycelium (1 : 600). 

of the steam. The vacuum is relieved by allowing sterilised air filtered through cotton- 
wool (see p. 124) to enter ; the maintenance of a slight pressure inside the vessel prevents 
the entry of germs. By stirring the starch and running cold water down the outer walls 
of the cylinder 1000 hectols. of boiling wort may be cooled in five hours to 38 ; this 
is the most suitable temperature for the Mucor fermentation, but a great part of the 

16 Balling), complete attenuation is obtained only in very dilute worts (7 to 8 Balling, these giving 4 to 4-5 per 
cent, alcohol) ; Mucor ft, on the other hand, forms only 0-75 grm. of acid, and can ferment worts at 10 to 17 Balling 
(which give 8 to 9 per cent, of alcohol) without oxidising completely more than a very small proportion of sugar. 
Calmette studied more particularly the saccharifying properties of Amylomyces Rouxii, but in 1897 Boidin 
and Bolants, and simultaneously Sanguinetti (Institut Pasteur, 1897) found that this mould is also capable of 
transforming sugar and dextrin into alcohol ; it was found later that Mucor racemosus, which had been already 
studied by Pasteur, behaved similarly. In 1895 Professor Saito, of Tokyo, isolated Rhizopits oligotyorus, which 
acts like Amylomyces Rouxii. 



132 



ORGANIC CHEMISTRY 



sulphuric acid added must first be neutralised. A vat of 1000 litres capacity contains 
150 to 200 quintals (15 to 20 tons) of maize and six times as much water. 

The Amylomyces is cultivated in the laboratory on 100 grms. of rice and 200 c.c. of 
sterile wort, so that preferably spores are developed. Every culture-flask contains a 
total of about 0-1 grm. of spores, and this quantity is sufficient to inoculate 1000 hectols. 
of wort. The Mucor is introduced, under aseptic conditions, into the vats from above 
and the stirrer set in motion ; a little air is introduced, this issuing by an upper 
tube with a hydraulic seal. In the course of 24 hours the wort is attacked by an 
abundant growth of the Mucor. The mass is then cooled to 33 and, in order to com- 
plete the alcoholic fermentation more rapidly, a small quantity of ordinary yeast (500 c.c. 
of a wort culture, corresponding with 3 to 4 grms. of pressed yeast) is added. 

After 3 to 4 days, the alcoholic fermentation is complete (the carbon 
dioxide passes out at the top through the water-seal). Fig. 126 shows dia- 
grammatically a plant with five large fermentation vessels. 




FIG. 126. 

The advantages of the amyio-process are : (1) a considerable saving in 
malt, only about 1 per cent, being used instead of 12 to 15 per cent, by the 
old process ; further, air-dried malt is difficult to keep in hot countries ; 
(2) the reduction of the amount of yeast required to a minimum. The yield 
of alcohol is also sensibly increased, one quintal of maize containing 57 to 58 per 
cent, of starch yielding 37-5 litres of alcohol, i.e. 65 (often 66) litres of pure 
alcohol per 100 kilos of starch ; the old method of working gives only 60 to 61 
litres. 

The increase in the alcohol-yield is naturally due to the fermentation 
taking place in a wort uncontaminated with extraneous micro-organisms ; on 
rectification, 4 to 5 per cent, more good spirit (bon gout) are obtained than 
by the old process. 

Finally, the spent wash (residue after distillation) filters better, since it 
contains less dextrin and does not block the filter-presses. 

DISTILLATION OF THE FERMENTED LIQUID. As has already been stated, 
the fermentation is rendered the more complete by using worts which are not too con- 
centrated and yield 9 to 10 per cent, of ethyl alcohol. These fermented liquids contain also 



RECTIFICATION 



133 




FIG. 127. 



small quantities of various other substances, such as aldehydes, organic acids (acetic, 
propionic, butyric, lactic, succinic, &c.), certain higher alcohols (amyl, propyl, butyl ; 
glycerol), &c., besides the solid residues of cereals and yeast and small amounts of 
unfermented dextrin and starch. 

It was formerly not easy to separate the ethyl alcohol from these products, in spite 
of the great differences in boiling-point in some cases (amyl alcohol, 132 ; ethyl alcohol, 
78-4), and, as already explained on p. 109, this separation cannot be effected with the 
most exact fractional distillation, so that recourse must be had to rectification (see p. 3). 1 
Every distillation apparatus is now composed of four parts : 
(1) the boiler in which the alcoholic liquid is heated; (2) the 
rectifier ; (3) the dephlegmator ; and (4) the condenser. The 
liquid collecting in the dephlegmator returns to the column 
(hotter), where alcohol vapours are formed richer than those from 
which it was formed in the first distillation ; so that the alcohol 
vapours of the dephlegmator, uniting with the other vapours 
before the condenser is reached, contribute to form a more con- 
centrated alcohol. 

Apparatus with continuously working columns and with re- 
covery of the heat have been studied and applied since 1867 
(Savalle). 

The action of a rectifying column may be understood from Fig. 
127, showing part of the column, which is divided into a number 
of chambers communicating by means of tubes and placed above 
the boiler. The mixture of alcohol and water vapours from the 

Jj IBilg^aa boiling fermented wash below ascends the column from chamber 
to chamber through the central tubes, which are covered with 

ffl ^ caps dipping below the surface of the liquid in the chambers ; by 

this arrangement the mixed vapours are obliged to pass through 
the hot, condensed liquid, which slowly descends the column 
through the drop-tubes, when it reaches a certain level in each 
chamber. The vapours give up to the liquid mainly water-vapour, and the liquid gives 
up to the vapours preferably the alcohol it contains, so that the alcohol -vapour reaches 
the top of the column mixed with only a little water-vapour and passes to the condenser, 
whilst water almost free from alcohol flows downwards, forming vinasse or spent wash. 

With this column, 8 to 10 metres high and containing 20 to 25 plates and chambers, 
one distillation and partial rectification yields 
directly a crude 50 to 65 per cent, alcohol, and 
when this is subjected to a second similar 
distillation and rectification a concentration of 
90 per cent, or even 96 per cent, is attained ; 
each apparatus gives a high output. This is 
the procedure often adopted in France. 

Taller columns (14 to 18 metres) are, how- 
ever, used, especially in Germany, and these 

with efficient dephlegmators give 90 per cent, or even 96 per cent, alcohol in one continuous, 
although slower, operation. The cylindrical columns are advantageously replaced by 
square ones, which are less easily stopped up and more easily cleaned and repaired ; in 
place of the costly copper columns, cheaper cast-iron ones are now largely used. A square 
plate of such a Savalle column is shown diagrammatically in Fig. 128, the apertures and 

1 The first forms of distillation apparatus were used in the times of the ancient Arabs, and were termed alembics. 
The alchemists made improvements in the shape, especially of the part used for condensing. Simple distillation 
apparatus, like that used for obtaining distilled water (vol. i, p. 225), yield a highly aqueous spirit, termed phlegm. 
Argand, and later Adam (about 1800), utilised the heat of the aqueous alcoholic vapours distilling over to heat 
the liquid to be distilled. Solimani and Berard (1805) improved the apparatus so as to allow a distillate 
moderately rich in alcohol to be obtained in a single operation. Before the condenser was placed a vessel called 
a dephlegmator, which condensed part of the water-vapour and part of the alcohol (phlegm), more concentrated 
alcohol vapours passing to the condenser. The first really rational and complete apparatus for the fractional 
distillation of alcohol was constructed by Cellier-Blumenthal (1815), who used dephlegmators and the first rudi- 
mentary rectifiers ; but as early as 1813, A. Baglioni had placed semi-rectifying dephlegmators directly above 
the boiler. , 

The first column rectifying dephlegmator was devised by Derosne and Cail in 1817, and shortly afterwards 
widespread use was made of the very convenient Pistorius apparatus, with its flat, lenticular dephlegmators, 
which allows of 60 to 75 per cent, alcohol being obtained directly, and is still used in some of the smaller distilleries. 




FIG. 128. 



134 



ORGANIC CHEMISTRY 



tubes being sufficiently wide to avoid obstructions when dense fermented worts, rich in 
solid matters, are distilled. The heating of the column and of the liquid is no longer 
effected by direct steam, as this causes useless dilution ; indirect steam is employed with 




FIG. 129. 



a tubular heater, to be described later. In order to obtain regularity of working and 
constancy in the alcoholic strength an automatic steam regulator is used (see below), 
and the supply of fermented wash to the apparatus is so controlled that the yield and 
strength of the alcohol remain uniform. The heat of condensation of the alcohol vapours 
is recovered to heat the wash, and the latter, before being introduced into the top of the 



CONTINUOUS DISTILLATION 



135 



column, is passed through tubular heaters so as to utilise also the heat of the spent wash 

before this is discarded. 

Fig. 129 shows the whole of a Savalle continuous distilling apparatus. The wash to 

be distilled passes from large constant -level tanks, situate 
on the upper floors, through the tube m, furnished with 
a regulating cock, 2, into the bottom of the heater, C, 
from which it issues at the top, after serving to condense 
the alcohol vapours coming from the column by the tube 
k ; these vapours, however, first yield a little condensed 
spirit in B, this being carried to the column by the tube r. 
The heated wash passes along the pipe q to the top of 
the column and slowly descends, meeting meanwhile the 
ascending vapour current, to which it gradually gives 
up its alcohol, as stated above (see Fig. 127). The 
alcohol condensed in the wash -heater is cooled in the 
condenser, D, below, through which cold water circulates. 
If the wash is heated in the wash -heater sufficiently to 
form vapour this passes into the small dephlegmator, H, 
whence the condensed alcohol and water are led by the 
tube S r to the column, whilst the alcohol vapour which 
is not condensed proceeds through t to the condenser 
along with the other alcohol. When all the plates of 
the column are covered with wash, steam is passed 
in from below by heating the exhausted vinasse by 
pipes from the heater, G, in which superheated steam 
from suitable boilers circulates ; this steam is regulated 
by the tap j, which in its turn is controlled by the 
automatic regulator F. When the distilled alcohol issues 
from the test-glass, E, the access of wash through 2 is 
regulated so that the alcoholic strength remains con- 
stant. In the column the wash traverses a path more 




FIG. 130. 



than 125 metres in length, the total absorptive 
surface being more than 200 metres, so that every 
litre of wash, before exhaustion, meets a surface of 
vapour 200 metres long. In this way 30,000 kilos 
or more of wash can be distilled per day without 
interruption of the working for months. 

Fig. 130 shows Savalle 's tubular heater more in 
detail. Steam under pressure from ordinary boilers 
traverses the regulator, E, and passes through 
the tube i to a large metallic cylinder, G, which 
contains a series of vertical tubes connecting 
the upper chamber, 0', with the lower one, Q" ; 
the latter is filled with almost exhausted vinasse 
supplied from the lower part of the Savalle column 
by the pipe x. The spent wash, which is already 
very hot, is thus easily brought into a condition of 
vigorous ebullition and loses the last traces of 
alcohol, which rise with a large quantity of steam 
through the pipe y into the Savalle column. The 
exhausted spent wash is discharged continuously 
from the tube 7, whilst the condensed steam 
issues from the tap 8. 

Fig. 131 shows the automatic regulator of the pressure and steam in the distillation 
and rectifying column. In order that it may pass through all the layers of liquid on the 
plates of the column the steam must be at a certain pressure in the column itself ; this 
pressure increases or diminishes according as the quantity and temperature of the steam 
rise or fall, and the greater the supply of steam the more dilute will be the alcohol. If 
the column is connected with the pressure regulator by means of the tube F(f in Fig. 129), 




FIG. 131. 



136 ORGANIC CHEMISTRY 

then, when the pressure increases, the water in the lower chamber, A, of the regulator is 
forced along the tube B to the upper chamber and raises a float, C, which operates the 
lever D, and so partially closes the tap (or valve) E controlling the supply of steam to the 
heater, G ; owing to the diminished supply of steam the pressure falls. In the opposite 
case, when the pressure in the column is smaller than that necessary for regular distilla- 
tion, so that the concentration of the alcohol (measured in E, Figs. 129 and 132) becomes 
too high and the yield too small, the water of the upper chamber of the regulator descends 
to the lower one, the float, C, hence falling and the steam-cock, E, opening a little. With 
these regulators, which are sensitive to variations of one -thousandth part of an atmo- 
sphere, the distillation is automatically regulated and requires very little personal 
control. 

'" The constancy of the strength of the alcoholic distillate is controlled by the test- 
glass, E (see Fig. 132), which is situated in the alcohol discharge tube and contains an 
alcoholometer fitted with a thermometer, so that the concentration and temperature are 
indicated continuously. 

Of the variously highly perfected forms of apparatus (Ilges, Coffey, Pampe, the last 

of. which gives very pure spirit by distillation under 
reduced pressure) used in England, Germany, Russia, 
&c., which allow of the continuous and direct pro- 
duction of 90 to 96 per cent, alcohol without special 
rectification and refining (when the first and last 
products of distillation foreshots and tailings are 
kept separate ; see later), we shall refer only to 
the apparatus of Siemens Brothers, which is largely 
used in Germany (Fig. 133). The column is com- 
posed of three principal parts : the heater (or pre- 
heater), A, the distillation column, B, and the recti- 
fier, C ; the whole is formed of superposed cast-iron 
discs or rings fitted with pasteboard packing and 
held tightly together by bolts extending from the 
top to the bottom. Inside are plates arranged 
FIG. 132. spirally round a central tube, D, which passes about 

half-way up the column to / ; the liquids thus tra- 
verse a long path, so that a large production is possible with a relatively small tower-space. 
The apparatus is also economical since it is not necessary to construct it of copper. The 
heater, A (see also Fig. 134, A), contains, in the chambers a and o, hot spent wash which 
comes from the top of the column. Between these hot chambers are arranged alternately 
others in which circulates the cold wash or wine to be distilled ; this is supplied through 
the pipe d by means of high -pressure pumps, and begins to be heated as it descends the spiral 
chambers between the hot ones containing the spent wash. When it reaches the bottom 
the hot wash passes into the central pipe D, and rises to the higher level,/, in the distillation 
column, B (which embraces the space between d and E). The pipe D empties on to the 
perforated spiral plates (see Fig. 134, B) and, as it descends, the wash meets a current of 
steam rising from the tube o through B. In this way the alcohol liberated from the wash 
rises with the steam through the perforations of the spiral plates and thus continually 
meets fresh quantities of wash and becomes continually richer in alcohol, as is shown 
in Fig. 134, B. The wash, thus deprived of alcohol, reaches the bottom as very hot 
spent wash, which, before leaving the column, traverses the chambers of the heater 
(shown in Fig. 134, A) and is then discharged continuously from the pipe J K, at a lower 
level than /. The mixed alcohol and water vapours enter the rectifying compartment, E, 1 
which is formed of plain discs and is filled with wash, the level of which can be seen through 
suitable glass windows. The alcohol vapours rise into the rectifier, C (more properly 
termed a fractionator or dephlegmator, see p. 133), formed of non -perforated and hence 
non-communicating spiral chambers (Fig. 134, C), in some of which circulate the ascending 
vaporous mixture, whilst the alternate ones are traversed by a descending current of 
water ; the latter is not very cold, as it comes from the top of the condenser, S (by means 
of the pipe t), so that it condenses mainly steam and only a little alcohol vapour, 

1 Pampe (Ger. Pat. 199,142, 1908) suggests placing, before the rectifying compartment, a steam-turbine with 
rapidly rotating vanes, which separate all the suspended drops or impurities from the vapours. 




RECTIFYING COLUMNS 



137 



which falls into the distilling column again. The alcohol vapours gradually become 
more and more highly concentrated and pass through the tube F to the refrigerator, S, 
where they condense and are cooled by water flowing in at s and out at t. By means of 
a sample taken from the column B by the tube p 
and examined in the tester, T, it can be ascertained 
if the spent wash is completely free from alcohol. 

In some cases it is observed that the spirit from 
such a cast-iron apparatus absorbs traces of hydro- 
carbons and of hydrogen sulphide which are formed 




FIG. 133. 



ConC.atco* 

. f nol vapoun 

JLyueous alcoltol vapour: 

FIG. 134. 



from the iron and give an unpleasant taste and smell to the alcohol ; this may, perhaps, 
depend on the quality of the metal and on the newness of the apparatus. 

We shall mention finally the attempts which have been made, first by Perrier in 1875, 
to transform the vertical column into a horizontal distilling and rectifying column with 
a central rotating axis carrying helically arranged blades, which transport even a very 
dense wash from one end to the other, whilst the opposing current of steam removes the 
whole of the alcohol. The process was perfected by Sorel and Savalle (1891), who arranged 
the numerous vertical chambers of the horizontal column in a more rational manner. 
These forms are not yet free from disadvantages, but they have the advantage of being 



138 



ORGANIC CHEMISTRY 



considerably more economical to construct and of bringing all the taps conveniently to 
hand on the ame level. 

Lastly, Guillaume eliminated various defects of these columns and at the same time 
retained all their advantages by employing very simple and convenient inclined columns 
(made by Egrot, of Paris), which allow of very dense washes being employed without 
danger of obstruction. Fig. 135 shows the complete Guillaume-Egrot apparatus, and 
the description of the various parts given underneath will indicate the way in which it 
works. The cross-section shown in Fig. 136 gives an idea of the internal arrangement of 
the inclined column, and Fig. 137 represents the ground plan of the column, the arrows 
indicating the horizontal, zigzag course followed by the liquid from the highest part of 
the column, whilst the vapours ascend the column in a zigzag vertical path and bubble 
through the liquid in all the chambers formed by the numerous vertical partitions. With 
relatively small plant, which can be mounted on portable cars (see later), 30,000 litres or 




FIG. 135. 

A, distilling column ; a, entrance of the wash into the heater or refrigerator ; B, condenser and 
heater; b, hot wash pipe; C, adjustable steam regulator; c, exit for spent wash;.D, hot wash 
extractor used as heater ; d, steam-tap ; E, test-glass giving the strength of the alcohol ; e, valve 
regulating flow and hence strength of the alcohol ; h, entrance of water into refrigerators in case 
of need. 

more of wash, containing 10 per cent, of alcohol, can be distilled per 24 hours, 90 per cent, 
alcohol being produced. 

In the modern distillery the consumption of steam should not exceed 25 kilos (about 
3 kilos of coal) per 100 kilos of wash, and the consumption of water in the condenser 
should not exceed 80 litres. 

RECTIFICATION OF ALCOHOL. The alcohol obtained with the ordinary Savalle 
apparatus is not sufficiently concentrated or pure to be placed on the market, and even 
that obtained with other forms from washes which have nqt been fermented with selected 
yeasts should be freed by rectification and refining from various impurities which impair 
the colour, smell, and taste. These impurities may be more volatile than alcohol (i-_uch 
as aldehydes and certain esters) or less volatile (as acetic and butyric acids ; propyl, 
isopropyl, and amyl alcohols ; various esters, &c.), and they are separated from the true 
alcohol if, in the redistillation and rectification, the portions which distil most readily 
(foreshots) and also the least volatile portions (tailings or fusel oil, which has a very 



PROCESS OF RECTIFICATION 



139 




disagreeable odour if obtained from potatoes, molasses, or maize, but a pleasing odour if 
derived from grapes, fruit, &c. ) are kept apart. 

Beatification apparatus usually consists of a large copper or iron boiler, A (Fig. 138), 
which is heated with an indirect steam-coil and on which is mounted the copper rectifying 
column, B. Above this and to one side is a large dephlegmator, G, which serves as a heater, 

and is of importance not 
so much for condensing the 
less volatile products (water, 
amyl alcohol, &c.) as for 
furnishing a continuous and 
abundant supply of a suitable 
alcoholic liquid to wash the 
vapours arriving at the top 
of the column ; it is, however, 
quite useless to employ several 
dephlegmators, as was erro- 
neously done in the past. The 
foreshots, which have a con- 
centration up to 94 per cent, 
and boil at 85, are collected 
separately. Then from 85 to 
102 alcohol passes over. The 
tailings, boiling above 102, 
are collected in the bottom of 
the column by shutting off the 

PIG. 136. steam and thus emptying the 

plates. The quantities of these 

products vary according to the quality of the alcohol required ; thus 20 per cent, of 
foreshots and tailings may be obtained and 80 per cent, of alcohol (bon gout extra), or 
5 per cent, of foreshots and tailings and 95 per cent, of alcohol (bon gout). 

This apparatus does not work continuously, the boiler requiring to be discharged 
and recharged. Attempts 

y*T>tv j^ 

9 



to render the process con- 
tinuous were met with suc- 
cess in 1881 (E. Barbet) in 
spite of the difficulty of 
separating the pure alcohol 
from an impure product 
that boils below it and 
another that boils above it. 
This is effected by carrying 
out the operation in two 
phases, which are, however, 
continuous ; in the first 
phase the foreshots are 
driven off and the alcohol 
distilled from the remaining 
liquid, the tailings being left 
behind. The boiler is then 

replaced by a rectifying column, which receives the impure product and distils the 
foreshots, passing the residue continuously at a certain height to a second lower column 
at the side ; this distils and rectifies the pure alcohol and retains in the lowest chamber 
of the column the tailings, which are continuously discharged. 

In the Savalle rectifiers 45 kilos of coal are consumed per hectolitre of pure rectified 
alcohol. Continuous rectification results in a saving of almost 50 per cent, of fuel compared 
with the discontinuous process. During rectification the loss of alcohol is 1 to 2 per cent., 
and the cost of rectification varies from 3 to 3-5 lire (2*. 6d. to 3*.) per hectolitre. The firm 
of Savalle holds that it is more economical to use cold air than water in the refrigerators of 
the condensers, 




FIG. 137. 



140 



ORGANIC CHEMISTRY 



Attention may lastly be drawn to the ingenious although complicated Perrier 
distilling and rectifying apparatus, in which the vapours of alcohol, water, higher 
alcohols, and aldehydes are pacsed successively into columns filled with glass beads and 
surrounded by a jacket containing a liquid boiling at a constant temperature, the latter 
bsing hence assumed by the whole of the tower. In one of these, having a tempera- 
ture of 85 to 90, only water and 
the tailings are condensed ; the 
vapours then pass into a second 
tower, kept at 75, where all the 
ethyl alcohol (which can be recti- 
fied in another tower) separates ; 
the vapours from this form the 
foreshots and are condensed in a 
succeeding tower. 

OTHER PRIME MATERIALS 
FOR THE MANUFACTURE OF 
ALCOHOL. (1) Beetroot and Mo- 
lasses. It is especially in France 
that considerable quantities of 
beet are used for the manufacture 
of alcohol instead of sugar ; this 
is never done in Germany or Italy. 
The beets are washed, minced, and 
the pulp exhausted by pressure, 
maceration, or diffusion with water. 
This treatment is described in the 
section on sugar. 

The spirit obtained from the 
beet is less pure than that from 
potatoes, containing more propyl 
and butyl alcohols but less amyl 
alcohol. 

Of more importance in Italy 
and various other countries is the 
utilisation of beet-molasses. 1 

The complete fermentation of 
molasses has presented many diffi- 
culties, which have now been over- 
come. Formerly, after the molasses 
was diluted to 8 to 10 Be. (this 
was carried out in vats provided 
with stirrers, see Fig. 139), it was 
slightly acidified with sulphuric acid 
(2-5 grms. of free H 2 SO 4 per litre), 
as the reaction is usually alkaline. 
The liquid was then boiled for some 



1 These are the dense, viscous, and 
FlG. 138. blackish mother-liquors which remain from 

the final crystallisation of the sugar (which 

e) and from which no further sugar will crystallise although 45 to 50 per cent, are present (see explana- 
tion in the section on Sugar) ; it has a density of 40 to 45 Be. (74 to 84 Balling). The composition of beet- 
is as follows : water, 16 to 20 per cent. ; sugar, 44 to 52 per cent. ; non-nitrogenous extractive matters, 
10 to 15 per cent, (largely pentoses) ; nitrogenous compounds, 6-5 to 9-5 per cent, (of which only one-third consists 
[ proteins, the rest being amino-acids) ; ash (deducting CO 2 ), 8-5 to 11 per cent. In Italy the working-up of 
nolasses has assumed considerable importance during the last few y^ars, owing to a change in the method of 
taxing sugar ; previous to 1903, sugar recovered from molasses by somewhat expensive processes (see Sugar) 
was exempt from taxation, whilst nowadays all sugar produced is taxed uniformly, so that the manufacturers 
nnd it advantageous to sell the molasses to the distillery at 4s. 9d. to 6s. 5d. per quintal. 

In Germany, Belgium, and part of France, it is found to be more convenient and rational to utilise a large 
proportion of the molasses as cattle-food after absorbing it by highly porous vegetable substances. In Italy, 
tumelina, patented by E. Molinari, and sanguemelassa (blood-molasses), patented by L. Fino, are manufactured ; 
the residues of dried tomatoes (Squassi, Bono) and various other dried industrial products are now used as absor- 
bents. In Germany more than 1,500,000 quintals of molassic fodder are consumed ; Italy produced 400,000 
quintals in 1908 and more than 480,000 in 1909 




ALCOHOL FROM MOLASSES, FRUIT, ETC. 141 

hours in a current of air in order to eliminate the volatile acids (nitric, &c.) liberated, 
and, after cooling it to 15, alcoholic fermentation was initiated by the addition of 
vigorously fermenting liquid ; the excess of acid which forms is gradually neutralised 
with chalk. The spirit thus obtained is difficult to purify as it contains an aldehyde 
and various acids which boil at a very low temperature. 

To-day, however, the process is much more simple, as Jacquemin and Effront have 
devised various methods of preparing races of yeast capable of living actively in worts 
rich in salts (nitrates, carbonates, &c.), such as those prepared from beet-molasses. In 
the past the difficulty of fermentation was attributed to the presence of nitrates, but it 
appears from Fernbach and Langenberg's experiments (1910) that nitrates, even in 
proportions as great as 0-3 per cent., facilitate fermentation. 

(a) In the Jacquemin process the fermentation is initiated in small quantities of 
wort in suitable vessels (see Fig. 123, p. 125), and the wort of the last rather larger vessel 
(into which is also placed a little hydrofluoric acid, to which the yeast has been previously 
" acclimatised ") serves to pitch a 200-hectol. vat containing diluted, non-sterilised 
molasses, to which has been added 8 to 10 kilos 

of calcium hypochlorite, this preventing the de- 
velopment of heterogeneous organisms during the 
first few hours without damaging the yeast 
already adapted to chlorine. By means of this 
vat two other 500-hectol. vats of similar 
diluted molasses can be brought into a state of 
vigorous fermentation ; the fermentation takes 
place so rapidly (and this is the most specific 
action of these yeasts) that in three days the 
Avhole of the molasses is fermented, there being 
thus no time for the development of extraneous 
germs causing harmful secondary fermentations. 

(b) The Effront process is still more simple, 
and is based on the use of selected yeasts specially 
adapted to molasses worts and endowed with 
exceptionally rapid fermenting properties ; these 

yeasts are placed under such conditions that they easily overcome deleterious 
bacteria (namely, the addition of resin) 1 and complete the fermentation before these 
become harmful. To the molasses simply diluted with water and not sterilised are 
added these special yeasts together with 1 kilo of colophony per 10 hectols. of wort ; 
in three days the fermentation is complete. In 1903 almost 1,000,000 kilos of colophony 
were used in France for this purpose. 

(2) Alcohol from Fruit. This is not of great industrial importance, 
although in certain districts and in certain years it assumes considerable 
magnitude. In Italy, dried figs of little commercial value, carobs, &c., are 
used ; and, in other countries, plums, apples, pears, &c. These fruits often 
give an irregular, and seldom a complete, fermentation, owing to conditions 
similar to those encountered with beet-molasses. Hence, as in the latter case, 
use is made of very active yeasts adapted, where possible, to these special 
worts. 

The alcohol obtained from these worts has a characteristic odour indicating 
its origin. 

* Effront observed that the law of the strongest, which is often verified in bacteriology the most numerous 
and powerful bacteria rendering life impossible to weaker ones scarcely ever holds in the case of .alcoholic fer- 
mentation, where, even though the harmful bacteria are less numerous than the yeasts, the latter are seldom 
victorious, the bacteria often entirely arresting alcoholic fermentation even when the conditions are favourable 
for the latter. 

According to Effront, this is owing to the different specific gravities possessed by yeasts and bacteria, which 
hence live in different, relatively distant strata, so that there is no opportunity for the application of the law 
of the strongest -which consists in the production by certain micro-organisms of poisonous substances preventing 
other forms from developing. Effront hence proposes to add suitably emulsified resin (colophony) to the worts 
at the beginning of Uie fermentation ; this has the property of coagulating only the bacteria, which become 
denser and are brought into more intimate contact with the yeast, the latter then being in the most favourable 
condition for the annihilation of the bacteria. The resin itself is not the cause of the death of the bacteria, as 
Effront states that these can be readily cultivated in the pure state in presence o"f resin (private communication). 




FIG. 139. 



142 ORGANIC CHEMISTRY 

(3) Alcohol from Woody Substances. This is a subject which has aroused con- 
siderable interest during about the last twenty years. Many attempts have been made 
to transform a part of the wood (sawdust, peat, &c.) into fermentable sugar by the action 
of acids on the matter (lignin) encrusting the 'wood and not on the cellulose. In Chicago 
the process was applied on a vast industrial scale according to A. Classen's patents 
(Ger. Pats. 130,980, 1899, and 161,644, 1904). 100 kilos of wood (with 25 per cent, of 
moisture) are treated in an autoclave for an hour with about 100 kilos of aqueous sulphur 
dioxide and sulphuric acid in presence of steam at 6 to 7 atmos. pressure (150 to 165). 
The excess of sulphur dioxide is eliminated by means of a current of air, the residue being 
boiled with water or extracted in diffusers, and the liquid neutralised with calcium 
carbonate and fermented ; x about 8 litres of pure alcohol are thus obtainable, and the 
residues are partially utilisable for making paper. It is not improbable that in the near 
future wood and the more economical wood refuse will replace cereals and potatoes in spirit 
factories. 2 In France, England, and the United States there were in 1910 four factories 
making alcohol from wood and obtaining yields of 7 per cent. 

(4) Alcohol from Wine, Lees, Vinasse, and Withered Grapes. In seasons when 

1 Wood thus yields a product contaiuing 35-36 per cent, of solid residue, 34-63 per cent, of water, 10-97 per 
cent, of fermentable reducing sugar, 3-21 per cent, of non-fermentable reducing sugars (pentoses : xylose, &c.) : 
0-35 per cent, of sulphuric acid, and 0-77 per cent, of other acids. 

As early as 1820, Braconnot observed that sugar is formed when wood or even cotton cloth is treated with 
sulphuric acid. Later on Melsens obtained a good yield by treating cellulose with dilute sulphuric acid in an 
autoclave under pressure. In 1860 Pettenkofer investigated this process and showed that it could, at that time, 
compete with the use of potatoes. Still later, Basset prophesied a yield of 32 per cent, of alcohol from the similar 
treatment of wood (I). Simonson, in 1889, treated wood under pressure with dilute sulphuric acid, transforming 
25 per cent, of it into sugar (78 per cent, of which was fermentable) and obtaining a practical yield of 6 to 7 litres 
of pure alcohol (Third International Congress of Applied Chemistry, Berlin, 1903). 

Ileiferscheidt (1905) overcame the resistance of the wood to penetration by liquid acid (met with also by 
Classen) by causing sawdust to absorb two-thirds of its weight of sulphuric acid (sp. gr. 1-65) and subjecting 
the mass to the maximum pressure of a hydraulic press ; simple digestion of the mass with water and nitration 
gave a fermentable liquid and a yield of 6-5 per cent, of alcohol on the weight of wood (pine, containing 53 per 
cent, of cellulose) taken. A similar yield is obtained by treating the wood with five times its weight of 1 per 
cent, sulphuric acid solution at a pressure of 8 atmos. for fifteen minutes. He confirmed the observation that the 
pentosans of the wood do not ferment, and with pure cotton he obtained as much as 13 per cent, of alcohol. 

According to Xh. Korner, the addition of oxidising agents or of ozone, as was suggested by Both and Gentzen 
(1905), is of no advantage. He obtained the best yields by heating sawdust, straw, &c., with 0-5 per cent, sul- 
phuric acid for 2 hours in an autoclave at 6 to 8 atmos. ; only a small part of the molecular complex of the cellulose 
is converted into fermentable sugar, and he obtained a yield of alcohol equal to 15 to 18 per cent, of the weight of 
the true cellulose in the wood. Without the addition of sulphuric acid, the yield was about one-fourth less. 

P. Ewen and H. Tomlinson, of Chicago (U.S. Pat, 938,308, 1909) treated 400 kilos of sawdust, straw 
or stems of various cereals (with 30 per cent, of moisture) in autoclaves with 5 kilos of sulphuric acid of 60 Be 1 , 
diluted with 20 litres of water ; after complete digestion and agitation the temperature of the mass is brought 
in fifteen minutes to 135 to 160 by means of steam under pressure ; after half an hour the temperature is lowered 
rapidly to 100 by allowing the steam to escape, and the sulphuric acid then separated in the usual way. By 
this means 20 to 30 per cent, of the weight of the cellulose is transformed into fermentable sugar. A similar process 
is that of Eckstrom (Norw. Pat. 17,634, 1907). 

Classen's process, which has been tried on a large scale in North America, has exhibited various disadvantages : 
the time required for treating 2 tons of wood was as much as six hours, the consumption of sulphuric acid was 
large, part of the sugar was destroyed, and frequent repairs were necessary. The process was improved by 
Ewen and Tomlinson, and was worked in a factory near Chicago. Less acid was used and the treatment main 
tained only for forty minutes, the autoclave being rotatable and made of steel protected outside with fireclay 
This was filled with sawdust, sulphur dioxide (1 part per 100 of dry wood) being then passed in, and subsequently 
steam at 7 atmos. After forty minutes, the vapours of water, acetic acid, terpenes, and sulphur dioxide are 
passed into washing or absorption vessels, while the residual darkened sawdust is extracted with hot water : 
the aqueous extract is neutralised with chalk, filtered, fermented, and distilled. Rectification yields 94 per 
cent, alcohol free from methyl and higher alcohols, and containing only traces of furfural and other aldehydes, 
The cost of this alcohol seems to be less than three-halfpence per litre of 90 per cent, concentration. 

J. Ville and W. Mestrezat (1910) state that, whilst cellulose resists dilute solutions (up to 30 per cent.) of 
hydrofluoric acid, with 50 per cent, solutions, 100 grms. of cellulose yield 50 grms. of glucose 1 

According to the Swedish patents of J. H. Vallin and of Eckstrom, alcohol is obtained by treating the waste 
sulphite liquors of paper-mills in the hot with sulphuric acid and fermenting the liquid containing the glucose 
formed. The hot acid liquid has to be neutralised almost completely with chalk and decanted, the residue 
being then pressed in a filter-press ; the liquid is then cooled on piles to 30, pitched with yeast, aerated during 
fermentation (5 to 6 hours) and the dilute alcoholic liquid (0-7 to 0-8 per cent, alcohol) distilled. From 10 
cu. metres of the sulphite liquors are obtained 60 litres of 100 per cent, alcohol (which is, however, of bad flavour 
and is used for denaturation). For a factory producing 60 tons of cellulose per day, i.e. 600 tons of waste sulphite 
liquors, the cost of tanks, pumps, piles, distilling apparatus, filter-presses, &c., may be taken as about 6000, 
and the alcohol produced (36 hectols. per day) would cost (including all expenses, but excluding taxation) 10s. 
to 11. per hectolitre at 100 per cent, strength. The problem of the disposal of the waste liquors (which con- 
taminate the rivers) of paper-mills is not, however, solved in this way, since the liquid still contains much decom- 
posable organic matter after the distillation of the alcohol. Before starting such an industry, it is also necessary 
to consider the condition of the market, so that there may not be an over-production of alcohol and hence 
depression of prices. 

In 1910 there were two factories in Sweden for the manufacture of alcohol from these waste sulphite liquors : 
that at Billingfors prepared methyl alcohol (15 kilos per ton of wood pulp) by H. Bergstrom and H. Fahl's process ; 
the other at Skutskiir manufactured ethyl alcohol. For every ton of cellulose there are obtained 8 to 9 tons of 



ALCOHOL FROM WINE RESIDUES 



143 



wine is abundant and prices low and in general when there are spoilt wines (at 6s. to 
8s. per hectolitre), it is convenient to extract the alcohol from them, this being of use 
in the preparation of liqueurs and spirits. 

The distillation presents no difficulty and is carried out either in the large distilleries 
or with a Guillaume-Egrot apparatus (see p. 138), which is mounted on a car so as to be 
readily transportable, and can be used in places where there is little available water, since 
the coolers and condensers act as heaters and are fed with the wine to be distilled. It 
gives directly 90 to 94 per cent, alcohol. 

In the same way as wine, fresh lees or bottoms from wine vats (containing 4 to 6 per 
cent, of alcohol) and dried grapes l are treated. 

The distillation of vinasse, containing 2-25 to 3-5 per cent, of alcohol, is of considerable 
importance in Italy ; if this were all distilled it would yield about 250,000 hectols. of 
pure alcohol annually (for a production of 40 million hectols. of wine). Of the various 
forms of apparatus for the distillation of vinasse only those of Villard-Rottner and of 
Egrot will be described, as they are the commonest and differ little from other good types. 

The generator, K (Fig. 140), of the Villard-Rottner apparatus sends steam from the 
dome, M, into the three boilers, A, in succession, the steam entering at the bottom and 




FIG. 140. 



FIG. 141. 



issuing at the top of each. These three boilers contain the vinasse mixed with an equal 
volume of water. The vapours, which are rich in alcohol, pass through the pipe, E, to 
the dephlegmator, G, and are then condensed in the coil, 7, at a concentration little 
exceeding 50 per cent. When the first boiler is exhausted it is emptied and again charged, 
the steam passing meanwhile through the second and third ; the first boiler now becomes 
the third, the second being then emptied, so that two boilers are always in use. The 
hot water from the boilers is treated separately for the extraction of tartar (see this). 

In the Egrot apparatus (Fig. 141) the boilers, A, are arranged on pivots, so that they 

sulphite liquors containing, either dissolved or suspended, as much as 12 per cent, of organic substances and 
yielding alcohol at loss than \\d. per litre. 

Considerable interest was aroused in 1901 by the English patent of Dornig and Pratorius, according to 
which human faces yielded about 9 per cent, of alcohol, but it proved to be a fraud. 

There has been much discussion recently (1906-1907) concerning a process for extracting spirit from peat 
in a manner similar to that described for wood. These attempts date from 1870, and various patents were filed 
in 1882-1891. The most important tests were made in Norway in 1906 by the Reynaud process (1903), in which 
300 kilos of peat were treated in the hot with 700 kilos of water containing 7 kilos of sulphuric acid (66 Be.) 
under 3 atmos. pressure ; 600 litres of liquid were thus obtained and this was fermented with specially selected 
yeasts (Saccharomyces ellipsoideus), the yield being 25 litres of burning spirit at an inclusive cost of about 4-5<7. 
per litre, which is about double the cost of that obtained from ordinary starchy materials. In 1905, the Danif b 
Government offered a prize for the improvement of this process, but the yield was not increased although it varies 
somewhat (6 to 8 per cent.) with the quality of the peat ; in all cases the alcohol obtained in this way is too costly. 

1 In some countries at certain times in Italy dried grapes are used for the production of alcohol, especially 
Greek grapes, which are received from viticulturists by the Greek Government in payment of taxes, and are 
dried and placed on the European markets. These grapes are first macerated in tepid water, then crushed and 
fermented in the usual way ; the wine obtained may be used for mixing with other wines or for distillation. In 
1905-1907, in order to help the crisis in the South, the Italian Government granted a considerable rebatement 
of taxation on the alcohol obtained from grapes The Italian distillers then began to import large quantities 
-of Greek grapes (containing 50 to 55 per cent, of sugar), which could be delivered in the factory at about 13*. per 
' quintal, so that the southern viticulturists reaped no advantage from the rebate, which was hence abolished. 



144 ORGANIC CHEMISTRY 

can be inverted and rapidly emptied. Steam from the boiler, D, extracts the alcohol 
from the three boilers, which are arranged in series, as before, so that two are always in 
use while the third is being emptied and recharged. The alcohol vapours pass into the 
dephlegmator, B, and thence into the spherical rectifier, C ; R acts as a condenser and is 
cooled by water from the tank, K. The condensed alcohol passes along the tube, m, to the 
test-glass, M, and from there to the casks, t, at a concentration of 55 to 60 per cent. 

With the first apparatus, to treat 100 quintals of vinasse, yielding about 8 hectols. 
of brandy at 51 per cent., roughly 13 quintals of coal are consumed, whilst the Egrot 
apparatus uses much less than this for an equal yield. The brandy thus obtained has 
almost always a rather unpleasant flavour and is often used for rectification in the ordinary 
way (if too dilute it becomes opalescent) and is then left to age in oak casks so as to acquire 
a pleasing aroma. This result is obtained more rapidly by pasteurisation, that is, by passing 
the brandy through a coil surrounded by water at 60 to 65, or by passing a current of 
ozonised air through it (artificial maturation). The name cognac is given to the finest old 
French brandies. 

Alcohol from cereals can be distinguished from that obtained from wine, &c., as the 
latter always contains aldehydes (see later, Rimini's Reaction and Schiff's Reagent). 

REFINING AND PURIFICATION OF SPIRIT. After the introduction of rational 
methods of fermentation with selected yeasts and of more perfect rectifying appliances, 
the quantity of actual alcohol was considerably increased and it was generally sufficiently 
pure for ordinary commercial purposes. But when it became recognised that the harmful 
effects of alcoholism are aggravated by the presence in commercial alcohols for liquors, 
&c., of even minimal quantities of aldehydes and amyl alcohol, recourse was sometimes 
had to a special purification or refining of rectified spirits in order to give them a slight 
ethereal odour, which is greatly valued. Of the many and varied substances suggested 
for the purification, mention need only be made of charcoal in lumps calcined and cooled 
out of contact with air and placed in batteries of tall cylinders through which the alcohol 
is passed ; when the charcoal becomes inactive it is revivified by means of superheated 
steam at 600. The charcoal has an oxidising, esterifying, and decolorising action, but 
it does not fix the amyl alcohol. Treatment with fatty oils (which retain the aldehydes) 
and subsequent distillation are also used, as also are carbonates of the alkalis and alkaline 
earths. Treatment with oxidising agents ozonised air, potassium permanganate or 
dichromate, nitric acid, chloride of lime, &c. has the disadvantage of forming acetic 
acid and ethyl acetate. Consequently Naudin prefers reducing the aldehydes with nascent 
hydrogen formed in the liquid itself by means of a copper-zinc couple. 

R. Pictet has devised a totally different process : owing to the variations (at different 
temperatures) of the maximum vapour pressure of volatile liquids, he ascertained that 
the vapours obtained from a mixture of water or other substances with alcohol are the 
richer in alcohol the lower the temperature to which the mixture is heated. He boils the 
mixture at 50 to 60 in a vacuum and then rectifies the vapours in a column at a tempera- 
ture of 30 or 40, obtained by means of a sulphur dioxide refrigerating machine. 
The apparatus is somewhat complex, but it yields a well-refined pure spirit. 

TESTS FOR THE PURITY OF ALCOHOL. The tests mentioned on p. 109 will 
detect traces of water in so-called absolute alcohol. 

If alcohol is highly purified (puriss.), 10 c.c. of it, mixed with 1 c.c. of water and 1 c.c. 
of 0-1 per cent, potassium permanganate solution, should maintain its red colour for 20 
minutes, or for at least five minutes if the alcohol is termed pure ; it should not become 
turbid on dilution with water, should give neither an acid nor an alkaline reaction (with 
phenolphthalein), and should remain unchanged with ammoniacal silver nitrate solution. 
To test for aldehydes the alcohol is diluted with water and a few drops distilled and tested 
by Rimini's reaction (see p. 109) ; or, for aldehydes in general, by Schiff's reagent(fuchsine 
solution decolorised with sulphur dioxide : 0-5 grm. of fuchsine is dissolved in 500 c.c. 
of water and decolorised with 10 c.c. of sodium hydrogen sulphite solution of sp. gr. 1-26 
and 10 c.c. of concentrated HC1) ; a few c.c. of this reagent are coloured red when shaken 
with a few drops of alcohol containing traces of aldehydes. 

Of more importance is the quantitative estimation of the fusel oil 1 (always formed in 

1 Fusel oil has a varying composition : 14-24 per cent, of water, 15-45 per cent, of ethyl alcohol, 6-14 per 
cent, of normal propyl alcohol, 10-25 per cent, of isobutyl alcohol, and 10-40 per cent, of amyl alcohol of fer- 
mentation. Traces of fusel oil may be detected by Kamarowsky's reaction, i.e. with salicylic aldehyde and 



ESTIMATION OF FUSEL OIL 



145 



alcoholic fermentation), which is made with Herzfeld and Windisch's modification of 
Rose's apparatus (Fig. 142) ; the method is based on the property possessed by chloro- 
form of dissolving the higher alcohols and a very little ethyl alcohol, at the same time 
increasing in volume. The alcohol is first diluted to a concentration of 30 per cent, by 
volume or, better, to the sp. gr. 0-9656 at 15-5 (see Table, p. 148 ; if the alcohol has a 
concentration, v, less than 30 per cent., then 10 (30 v) 1 c.c. of absolute alcohol should be 
added). The Rose tube (washed with alkali, acid, water, alcohol, and ether and well 
dried) has a cylindrical expansion at the bottom containing 20 c.c. up to the first mark ; 
then comes a tube 18 cm. long, holding 2-5 c.c. and graduated in O'Ol c.c. ; at the top is 
a pear-shaped bulb of about 200 c.c. capacity, closed with a ground stopper. The tube 
is placed in water at 15 and into it are introduced by a long funnel reaching to the lower 
bulb 20 c.c. of pure chloroform at 15, and then 100 c.c. of the alcohol 
diluted to 30 per cent, at 15 and 1 c.c. of sulphuric acid of sp. gr. 1-2857 
(38 per cent. H 2 SO 4 ). The tube is then closed, inverted so that all the 
liquid passes into the pear-shaped bulb, shaken vigorously for a minute 
(150 shakes) and placed erect in the water-bath at 15, where it is left for 
15 minutes after a rotatory movement has been imparted to the liquid so as 
to collect the drops of chloroform adhering to the walls. The increased 
volume of the chloroform is then compared with that obtained in a similar 
test with pure alcohol of the same concentration. If no blank experiment 
is made, 1-64 c.c. is subtracted from the increase in volume as being due to 
the ethyl alcohol dissolved. Each 0-01 c.c. increase hi volume of the chloro- 
form corresponds with 0-006634 per cent, by volume of fusel oil. For 
an alcohol rich in fusel oil which gave a final volume of chloroform of 
22-14 c.c. the true increase in volume will be 22-14 1-64-20=0-5 c.c. 
The percentage, /, of fusel oil by volume on the original alcohol (not on 
that diluted to 30 per cent.) is calculated by the following formula : 

_ (c-6)(100 + a) 
* = 150 ' 

where c is the uncorrected increase in volume of the chloroform, 6 is the 
correction, 1-64, due to the ethyl alcohol, and a indicates the number of 
c.c. of water or absolute alcohol added to 100 c.c. of the original spirit to 
bring it to 30 per cent. Example : If 80 per cent, alcohol is used, 171-05 
c.c. of water must be added to 100 c.c. to break it down to 30 per cent. ; 
100 c.c. of this then increases the volume of the chloroform from 20 to 
21-94 c.c., so that: 




/ = 



(1-94 -1-64) (100 + 171-05) 
150 



FIG. 142. 



= 0-54 per cent, by volume of fusel oil. 



The furfural is determined in 10 c.c. of distilled alcohol, to which are added 10 drops 
of colourless aniline and 2 c.c. of acetic acid ; if a red coloration appears after 20 to 30 
minutes furfural is present. 1 

sulphuric acid; H. Kreis's modification (1907) of this colorimetric reaction yields moderately accurate 
results. 

Fusel oil is now largely used for the preparation of amyl alcohol, which is used in the manufacture of fruit 
essences, for obtaining nitrous and other ethers, and for gelatinising explosives (nitrocellulose) ; during the last 
five years the price of fusel oil has risen from 65 to 170, and even 195 lire per quintal. Pasteur thought that 
the amyl alcohol (iso- and d-amyl) arose from the action of specific bacteria on the sugar. But in recent years 
F. Ehrlich has thrown doubt on the formation of an alcohol with a branched chain from a sugar with a direct 
chain, and has now shown that it is the proteins of the malt and their decomposition products which furnish 
nitrogen to the yeast for the synthesis of its protein constituents and at the same time form amyl alcohol. In 
fact, in the fermentation of a pure sugar, Ehrlich obtained a quantity of fusel oil proportional to the quantity 
of leucine added ; he was also able to obtain an amount of fusel oil equal to 7 per cent, of the alcohol formed 
(the usual amount being 0-4 to 0-6 per cent.) and, further, he succeeded in reducing the formation of fusel oil 
considerably by the addition of ammonium salts. The United States imported 2350 tons (122,000) of fusel 
oil in 1910 and 2900 tons (255,000) in 1911. 

1 The estimation of small quantities of benzene in denaturated alcohol can be carried out by means of Rose's 
apparatus (for more than 1 per cent, of benzene). The best method is to dilute 100 c.c. of the alcohol to a con- 
centration of 24-7 per cent, by weight and to distil the whole ; the first 10 c.c. of the well-cooled distillate are 
diluted to 20 to 25 c.c* with water in a graduated cylinder ; the volume of the benzene which separates is increased 
by 0-3 per cent., which is a constant error of the method. This method of Holde and Winterfeld (1908) is based 
on the fact that when the alcohol is diluted with water, the pressure of the benzene is considerably augmented, 
whilst that of the alcohol is diminished. 

To ascertain if methyl alt-olio as present in alcohol, 1 c.c. of it is treated with 1 c.c. of chromic acid solution 
II 10 



146 



ORGANIC CHEMISTRY 




FIG. 143. 



ALCOHOL METERS OR MEASURERS. These are important instruments, as in 
nearly all countries the manufacture of alcohol is subject to taxation which is calculated 
on the quantity of alcohol passing through a sealed meter indicating automatically the 
corresponding amount of pure alcohol (100 per cent.). The Siemens measurer is the one 
most used (Figs. 143 and 144) and somewhat resembles the gas-meter (see p. 50) even in 
its registration. The alcohol, which enters laterally by the tube I, is discharged into the 
inner central part of the drum, B, i.e. into D, this being divided longitudinally into three 
small chambers furnished with apertures, r 1 , r 2 , r 3 ; when the small chamber is about half 
full the alcohol falls into the large lower chamber (e.g. I), which has a capacity of 4 Hires. 
When this chamber is filled with alcohol the level of the latter reaches the chamber D, 
the alcohol then falling through r 2 into // and displacing the equilibrium, so that the 

drum, B, is forced round in the sense 
of the arrow. At the same time the 
first 4 litres of alcohol are discharged 
into the vessel C, which communicates 
with the storage reservoir by means 
of the tube G. The compartment II 
then occupies the position of 7, and 
so on. The axis of the drum is con- 
nected with a suitable automatic regis- 
tering device. At the same time, in 
the cylinder A in front of the drum, 
the alcohol which passes through raises 
the float, P, more or less according to 
its strength, and a screw, Q, operates the lever, T, and so moves the index, 8, the point of 
which registers the alcoholic strength on a paper ribbon moving along a carefully calcu- 
lated curve, X. In order that alcohols of different concentrations may be well mixed 
and so influence the float correctly, they are delivered at E, where there are two tubes ; 
one of these, a, collecting the lighter 
alcohol, rises and then descends (c), dis- 
charging into the bottom of A by the per- 
forated tube, e ; the denser alcohol passes 
preferably along 6 and is discharged 
through the perforated tube, d, at the top 
of A, so that mixing is rapid and com- 
plete. The registration is also independent 
of the temperature of the alcohol, as its 
expansion (or contraction) is allowed for 
by that of the float. 

ALCOHOLOMETRY AND TESTS 
FOR ALCOHOL. As a rule alcohol is 
sold practically by volume and not by 
weight ; 1 litre of absolute alcohol weighs 
0-7937 kilo or 1 kilo measures 1-2694 litre. 
Industrially alcohol is stated to be of so 
many litre-degrees ; thus 100 litres of 2 per cent, alcohol would contain 200 litre-degrees 
(100 x 2), and 100 litres of 50 per cent, alcohol would indicate 5000 litre -degrees, which 
would also be given by 1000 litres of 5 per cent, alcohol ; so also 75-48 litres of 100 per 
cent, alcohol would be expressed as 7548 litre-degrees. Alcohol is taxed on the basis of 
the number of litres of absolute alcohol. 

The alcohol-content of an aqueous alcoholic solution is deduced from the specific 
gravity determined by the Westphal balance, or directly by the Gay-Lussac alcoholometer 
(at 15) in France, or by the Tralles official alcoholometer (at 15-56) in Italy and Germany, 
these giving the percentage of alcohol by volume contained in 100 vols. of the aqueous 

and 5 c.c. of water, the whole being then carefully distilled until only 0-5 c.c. remains. The distillate is condensed 
in a long air-cooled tube and collected in a test-tube, the condenser-tube being washed out with 2 c.c. of distilled 
water. One drop of ferric chloride and two of albumin solution are added to the test-tube, which is shaken ; 
5 c.c. of concentrated sulphuric acid are then cautiously added. The immediate appearance of a violet ring at 
the zone separating the two layers indicates that the original alcohol contained more than 5 per cent, of methyl 
alcohol ; if the coloration appears after a minute, the proportion is 1 to 5 per cent, and if after two minutes less than 
]per cent.(A. Vorisek, 1909). 




FIG. 144. 



ALCOHOLOMETRY 



147 





FIG. 145. 



alcohol. The reading on the alcoholometer is made at the point of the stem coincident 

with the lower meniscus, which is well seen by looking rather below the surface of the 

liquid (Fig. 145) ; to avoid error, the alcoholometer must be so im- 
mersed that the whole of the graduated stem is not wetted (see 
vol. i, p. 75). To determine the percentage by weight contained 
in 100 vols. the percentage by volume is multiplied by 0-7937 
(specific gravity of absolute alcohol) and divided by the specific 

gravity of the alcohol examined (see Table on p. 148). 

To correct the alcohol reading determined at a temperature 

different from 15 (or 15-56 for the Gay-Lussac alcoholometer), 

the following moderately exact formula of Pranco3ur is used : 

x = c 0-392, where x is the number of Gay-Lussac degrees at 
15, c the number of degrees found at the non-normal tempera- 
ture, and t the number of degrees the latter is above or below 15 ; 

the + sign of the formula is used 
if the temperature is below 15 and 
the sign if it is above 15. Thus 
an alcohol showing 72 on the 
Gay-Lussac alcoholometer at a 
temperature of 28 would have : 
x = 72 - 0-39 x 13 = 66-93 Gay-Lussac at 15. 

With dilute alcoholic liquids of complex composi- 
tion (wine, beer, spirits, &c.) the alcoholic degrees cannot 
be deduced from their specific gravities. But, if a given 
volume, e.g. 100 c.c., is taken and distilled (Fig. 147) 
until all the alcohol has passed over (about 70 c.c.), the 
distillate can be made up to the original volume with 
distilled water and its specific gravity and alcoholic 
strength determined in the usual manner. In order to 
prevent frothing during the distillation of beer and wine 
a piece of tannin or a few drops of oil are added. In 
some cases the alcohol of wines and other liquors is 
determined by the Geissler vapoiimeter, which indicates 
the pressure of the vapours from the liquid heated at 100, 
By means of a Table the alcoholic strength may be read 
off, knowing the vapour pressure ; the latter is measured 
on a special barometric U-tube, B (Fig. 146), to one end 
of which is fixed the bottle, O, containing mercury and 
the alcoholic liquid and placed in the jacketed vessel, D, 
filled with steam from the boiler, A. This apparatus 
gives results which 
are influenced by 
several factors (dis- 
solved carbon dioxide, 

salts, &c.), so that little use is made of it. In more 

general use is the ebullioscope devised in 1823 by 

Groningen and subsequently improved by Tabarie 

(1833), Brossard-Vidal (1842), Malligand (1874), 

Salleron (1880), and Amagat (1885). Malligand's 

form (Fig. 148) is the most commonly used and is 

based on the different boiling-points possessed by 

alcoholic liquids of different concentrations. The 

reservoir, F, is provided with a cover, through which 

pass a thermometer, T, bent at a right-angle and a 

tube surrounded by the condenser, R. This cover is 

unscrewed and water poured into the reservoir as far as the lowest mark inside, the cover 

being then screwed on (the bulb of the thermometer does not touch the water). The 

burner, L, is then lighted under the small chamber, S, which is traversed by a brass tube 

communicating with the reservoir ; the part a' being rather higher than a, circulation of 



146. 




FIG. 147. 



148 ORGANIC CHEMISTRY 

WINDISCH'S TABLE FOR CALCULATING THE STRENGTH OF AQUEOUS 

ALCOHOL SOLUTIONS 



Sp. gr. 
at 
15 C. 


Grms. of 
alcohol in 
100 grms. 


C.c. of 
alcohol in 
100 c.c. 


Grms. of 
alcohol in 
100 c.c. 


Sp. gr. 
at 
15 C. 


Grms. of 
alcohol in 
100 grms. 


C.c. of 
alcohol in 
100 c.c. 


Grms. of 
alcohol in 
100 c.c. 


0-9999 


0-05 


0-07 


0-05 


0-9550 


31-66 


38-06 


30-21 


0-9992 


0-42 


0-53 


0-42 


0-9535 


32-55 


39-07 


31-01 


0-9985 


0-80 


1-00 


0-80 


0-9520 


33-42 


40-06 


31-79 


0-9978 


1-17 


1-48 


1-17 


0-9505 


34-28 


41-02 


32-55 


0-9970 


1-61 


2-02 


1-60 


0-9490 


35-11 


41-95 


33-30 


0-9963 


2-00 


2-51 


1-99 


0-9470 


36-21 


43-17 


34-26 


0-9956 


2-39 


3-00 


2-38 


0-9455 


37-01 


44-06 


34-96 


0-9949 


2-79 


3-49 


2-77 


0-9440 


37-80 


44-93 


35-66 


0-9942 


3-19 


4-00 


3-17 


0-9420 


38-84 


46-07 


36-56 


0-9935 


3-60 


4-51 


3-58 


0-9405 


39-61 


46-90 


37-22 


0-9928 


4-02 


5-03 


3-99 


0-9385 


40-62 


47-99 


38-09 


0-9922 


4-39 


5-48 


4-35 


0-9365 


41-61 


49-06 


38-93 


0-9915 


4-81 


6-01 


4-77 


0-9345 


42-59 


50-11 


39-76 


0-9909 


5-19 


6-47 


5-14 


0-9330 


43-31 


50-88 


40-38 


0-9902 


5-63 


7-02 


5-57 


0-9305 


44-51 


52-14 


41-38 


0-9896 


6-02 


7-50 


5-95 


0-9290 


45-22 


52-89 


41-97 


0-9889 


6-48 


8-07 


6-40 


0-9265 


46-39 


54-12 


42-95 


0-9884 


6-81 


8-48 


6-73 


0-9245 


47-32 


55-08 


43-71 


0-9877 


7-29 


9-06 


7-19 


0-9225 


48-24 


56-03 


44-47 


0-9872 


7-63 


9-48 


7-53 


0-9205 


49-16 


56-97 


45-21 


0-9866 


8-05 


10-00 


7-94 


0-9180 


50-29 


58-13 


46-13 


0-9860 


8-48 


10-52 


8-35 


0-9160 


51-20 


59-05 


46-86 


0-9854 


8-91 


11-05 


8-77 


0-9140 


52-09 


59-95 


47-57 


0-9849 


9-28 


11-50 


9-13 


0-9115 


53-21 


61-06 


48-46 


0-9843 


9-72 


12-05 


9-56 


0-9095 


54-10 


61-95 


49-16 


0-9838 


10-10 


12-50 


9-92 


0-9070 


55-20 


63-04 


50-03 


0-9832 


10-55 


13-06 


10-36 


0-9050 


56-09 


63-91 


50-71 


0-9827 


10-94 


13-53 


10-74 


0-9025 


57-18 


64-98 


51-56 


0-9822 


11-33 


14-01 


11-12 


0-9000 


58-27 


66-03 


52-40 


0-9817 


11-72 


14-48 


11-49 


0-8975 


59-36 


67-08 


53-23 


0-9811 


12-20 


15-07 


11-96 


0-8955 


60-23 


67-91 


53-89 


0-9807 


12-52 


15-46 


12-27 


0-8930 


61-31 


68-94 


54-71 


0-9801 


13-00 


16-04 


12-73 


0-8905 


62-39 


69-95 


55-51 


0-9796 


13-41 


16-54 


13-13 


0-8880 


63-47 


70-96 


56-31 


0-9791 


13-82 


17-04 


13-52 


0-8855 


64-54 


71-96 


57-10 


0-9786 


14-23 


17-54 


13-92 


0-8830 


65-61 


72-94 


57-88 


0-9781 


14-65 


18-04 


14-31 


0-8805 


66-67 


73-92 


58-66 


0-9776 


15-06 


18-54 


14-71 


0-8775 


67-95 


75-07 


59-57 


0-9771 


15-48 


19-04 


15-11 


0-8750 


69-01 


76-02 


60-33 


0-9766 


15-90 


19-55 


15-51 


0-8725 


70-06 


76-97 


61-08 


0-9761 


16-32 


20-05 


15-91 


0-8695 


71-33 


78-08 


61-97 


0-9756 


16-73 


20-55 


16-31 


0-8670 


72-37 


79-00 


62-69 


0-9751 


17-15 


21-06 


16-71 


0-8640 


73-63 


80-09 


63-56 


0-9747 


17-49 


21-46 


17-03 


0-8615 


74-67 


80-99 


64-27 


0-9741 


17-98 


22-06 


17-50 


0-8585 


75-91 


82-05 


65-11 


0-9736 


18-40 


22-55 


17-90 


0-8555 


77-15 


83-10 


65-94 


0-9731 


18-81 


23-05 


18-29 


0-8530 


78-17 


83-96 


66-63 


0-9726 


19-22 


23-54 


18-68 


0-8500 


79-40 


84-97 


67-43 


0-9721 


19-63 


24-02 


19-07 


0-8470 


80-62 


85-97 


68-23 


0-9716 


20-04 


24-51 


19-45 


0-8440 


81-83 


86-95 


69-00 


0-9710 


20-52 


25-08 


19-91 


0-8405 


83-23 


88-08 


69-90 


0-9705 


20-92 


25-56 


20-28 


0-8375 


84-42 


89-02 


70-65. 


0-9695 


21-71 


26-50 


21-03 


0-8340 


85-80 


90-09 


71-50 


0-9685 


22-49 


27-42 


21-76 


0-8310 


86-97 


90-99 


72-21 


0-9675 


23-25 


28-32 


22-47 


0-8275 


88-31 


92-01 


73-02 


0-9665 


24-00 


29-20 


23-17 


0-8240 


89-64 


93-00 


73-80 


0-9655 


24-73 


30-06 


23-86 


0-8200 


91-13 


94-09 


74-66 


0-9645 


25-45 


30-91 


24-53 


0-8165 


92-41 


95-00 


75-39 


0-9630 


26-51 


32-14 


25-50 


0-8125 


93-85 


96-00 


76-19 


0-9620 


27-19 


32-93 


26-13 


0-8080 


95-43 


97-08 


77-04 


0-9605 


28-19 


34-10 


27-06 


0-8040 


96-79 


97-99 


77-76 


0-9590 


29-17 


35-22 


27-95 


0-7990 


98-46 


99-05 


78-61 


0-9580 


29-81 


35-95 


28-53 


0-7925 


100-00 


100-00 


79-36 


0-9565 


30-74 


37-02 


29-38 











There are also Tables by Hehner, Haas, Tralles-Brix, Gay-Liissac, &c., which differ little 
(at most 0-1 to 0-2 per cent.) from that of Windisch. 

For any specific gravity not given in the Table the corresponding alcoholic degree can 
be obtained easily and with sufficient accuracy by proportional interuolat 



ALCOHOL STATISTICS, ETC 



149 



liquid takes place through the tubes and reservoir. When the mercury thread of the 
thermometer remains stationary owing to the water boiling and the steam hence having 
a constant temperature, the scale is adjusted by the screw, E, so that the zero-point corre- 
sponds with the end of the mercury column. The reservoir is then emptied, rinsed out 
with the wine, &c. (containing less than 15 per cent, of alcohol), and then filled with the 
wine to the upper mark, so that the thermometer bulb dips into the liquid when the cover 
is screwed on. The condenser is filled with cold water, the burner lighted, and the 
heating continued until the thermometer again shows a constant reading ; the corre- 
sponding scale-reading then gives directly the percentage of alcohol by volume. In tho 
case of sweet wines or beers it is advantageous to dilute with an equal volume of water, 
the result given by the instrument then being doubled. 

An ingenious and simple ca pillar imeter, recently devised by Bosla and constructed by 
the Italian (Enological Agency, Milan, gives the alcoholic 
strength of wines or spirits with sufficient accuracy in 
three or four minutes. 

The Table given in the footnote 1 indicates the volume 
of water to be added to 100 c.c. of alcohol of known 
strength in order to bring it to a definite lower concen- 
tration. This Table is calculated from the formula : 

/S'x. v \ 
x = 100 (. ~r- - 8} 

where v is the strength of the more concentrated 
alcohol, S its specific gravity, S' and V the specific 
gravity and alcoholic strength required, and x the 
quantity of water to be added to 100 c.c. 

STATISTICS, FISCAL REGULATIONS, DE- 
NATURED ALCOHOL. The annual production of 
alcohol is now about 21,000,000 hectols., 2 and of 
this 23 per cent, is made in Germany (the taxation 
amounting to 7,600,000 in 1907 and 8,000,000 in 
1909 ; in 1911 the consumption of alcohol in Germany 
fell to 3,650,000 hectols.), 20 per cent, in European 
Russia, 16 per cent, in Austria-Hungary, 14 per cent, 
in France, 15 per cent, in the United States, 10 per cent, in England, and 1-4 per cent, in 
Italy. In 1908 Turkey imported about 175,000 hectols. of alcohol (one-half from Russia), 




FIG. 148. 



Concen- 


GIVEN ALCOHOL AT 


tration 




desired 


95% 


90 % 


85% 


80 % 


75% 


70% 


65% 


60 % 


55 % 


50% 




by vol. 


by vol. 


by vol. 


by vol. 


by vol. 


by vol. 


by vol. 


by vol. 


by vol. 


by vol. 


90% 


6-4 




















85 


13-3 


6-56 


















80 


20-9 


13-79 


6-83 
















75 


29-5 


21-89 


14-48 


7-20 














70 


39-1 


31-10 


23-14 


15-35 


7-64 












65 


50-2 


41-53 


33-03 


24-66 


16-37 


8-15 










60 


63-0 


53-65 


44-48 


35-44 


26-47 


17-58 


8-76 








55 


78-0 


67-87 


57-90 


48-07 


38-32 


28-63 


19-02 


9-47 






50 


95-9 


84-71 


73-90 


73-04 


52-43 


41-73 


31-25 


20-47 


10-35 




45 


117-5 


105-34 


93-30 


81-38 


69-54 


57-78 


48-09 


34-46 


22-90 


11-41 


40 


144-4 


130-80 


117-34 


104-01 


90-76 


77-58 


64-48 


51-43 


38-46 


25-55 


35 


178-7 


163-28 


148-01 


132-88 


107-82 


102-84 


87-93 


70-08 


58-31 


43-58 


BO 


224-4 


206-22 


188-57 


171-05 


153-53 


136-34 


118-94 


101-71 


84-54 


67-45 


25 


287-0 


266-12 


245-15 


224-30 


203-61 


182-83 


162-21 


141-65 


121-16 


100-73 


20 


381-8 


355-80 


329-84 


304-01 


278-26 


252-58 


226-98 


201-43 


175-96 


150-55 


15 


539-5 


505-27 


471-00 


436-85 


402-81 


368-83 


334-91 


301-07 


267-29 


233-64 


10 


859-0 

^ 


804-50 


753-65 


702-89 


652-21 


601-60 


551-06 


500-50 


460-19 


399-85 

_^ 




c.c. of water to be added to 100 c.c. of the more concentrated alcohol. 



For example, if an alcohol of 90 per cent, by volume is to be diluted to 50 per cent, by volume, to 100 c.c. 
of the former must be added 84-71 c.c. of water. 
1 See Table on next page. 



150 



ORGANIC CHEMISTRY 



For every 100 litres of alcohol consumed as beverages the following amounts are used 
for industrial purposes : 54 litres in Germany, 19 in Austria, 18 in France, and 14 in 
England. 

These figures indicate the countries where alcoholism is causing the greatest amount 
of harm. 1 

PRODUCTION OF ALCOHOL IN THOUSANDS OF HECTOLITRES 





1902-3 


1904-5 


1905-6 


1907-8 


1908-9 


Observations 


Germany 


3383 


3791 


4020 




4500 




Austria-Hungary 


2318 


2480 


2700 




2650 




Russia . 


3855 


4196 


4500 




2700 




United States . 


2900 


2900 


2900 








France . 


1800 


2500 


2700 


2538 






England 


1297 


1300 


1284 


1400 






Holland . 


354 


367 


351 








Belgium 


328 


329 


389 








Sweden . 


186 


195 






220 


(Imports in 














1909 : 12,000 














hectolitres) 


Italy 


173 


300 


293 


463 






Denmark 


169 


155 


154 









In Germany the exportation varies considerably : 313,400 hectolitres in 1902, 14,000 in 1904, 194,000 in 1906, 
and 9700 in 1908. 

1 Alcoholism. The abuse of alcoholic beverages is leading to the ruin and decadence of certain nations, since it 
is largely the cause of depopulation and produces actual decay of the human organism. Alcoholism produces a 
diminution in stature, as is shown by the increased numbers of those unfit for military service ; it quickly leads 
to crime and folly, and renders the organism easily attackable by all kinds of disease, its effects being felt to the 
third generation. 

Alcohol acts as a poison which first excites and exalts, then intoxicates and depresses the psychic faculty 
more or less permanently. The abuse of wine and spirits is the real cause of much intestinal catarrh and of 
certain visceral lesions, and sometimes leads to chronic nephritis, heart-injury, enlargement and inflammation 
of the liver, hepatic cirrhosis, cerebral apoplexy, progressive paralysis, and often to madness. 

Among the industrial classes it is thought that alcohol warms, prevents cold, and gives greater strength during 
work, but this is a great error based on appearances. Almost as soon as it is swallowed, the alcohol of wine and 
spirits is absorbed by the blood by means of the capillaries and brought into contact with all parts of the organism, 
the nervous centres are then more or less paralysed, and the numerous capillaries under the skin dilate, since 
an increased amount of blood rushes to the skin itself. The drinker has, indeed, a red face ; but the sensation 
of great heat is only superficial ; if the surroundings are cold, the heat of the body is more easily dispersed. This 
explains why drunken men, sleeping on the roads in the winter, readily die of cold. Nansen, the famous Polar 
explorer, withstood temperatures 52 below zero without using alcoholic liquors. 

The International Congress on Industrial Diseases, held at Milan in 1906, declared that the use of alcohol 
" is unnecessary for the nourishment of the workman, and becomes harmful where the work is heavy or long. 
As regards useful effects in the food rations of the worker, alcohol may be advantageously replaced by sugar, 
coffee, and tea." Alcohol may diminish the using-up of fat in the organism and hence the consumption of proteins, 
but as a food it is very costly and of little effect. 

During the last few years alcohol-free wines have been prepared by crushing grapes from the best vineyards 
and subjecting the must to filtration and pasteurisation (heating to 60) so as to render it clear and prevent 
fermentation ; the wine is then stored in hermetically sealed, sterilised bottles. These wines retain the taste 
and fragrance of the grape and have considerable nutritive value since the sugar of the grape remains unchanged 
(15 to 20 per cent.). 

Alcohol also has a harmful effect on the reproduction of man, this explaining the slowness or absence of the 
increase in population of nations consuming much alcohol ; as in France, where 6,000,000 was spent in 1898 
on so-called aperitives (absinthe, bitters, Ac.) alone. In England 60,000,000 is spent annually on spirits, and 
in Switzerland even 6,000,000. Drink causes the direct or indirect death of about 45,000 people annually in 
France, 40,000 in Germany, 50,000 in England, 20,000 in Belgium, and 100,000 in Russia. In Italy, L. Ferriani 
stated that 627 cases of death in 1904 were evidently due to acute alcoholism. Dr. Marambat affirms that in 
France 72 per cent, of the criminals and 70 per cent, of the individuals (121,688) appearing annually before the 
courts make excessive use of alcoholic liquors. In Germany, A. Baer found that 41-7 per cent. (13,706) of the 
prisoners (32,837) were addicted to drink ; in Switzerland, it is 41 per cent. ; and in England, 33 per cent, of 
those sentenced at the Assizes. In Holland, four-fifths of the crime is attributed to alcohol, and in Sweden three- 
fourths. Similar figures to the above have been giyen for Italy. In various countries it has been found that 
25 per cent, of the lunatics are excessive alcohol drinkers. In the Salpi'triere Hospital of Paris, 60 out of 83 
babies afflicted with epilepsy had alcoholic parents. In Germany, 30,000 persons are attacked every year by 
alcoholic delirium and other cerebral disturbances due to abuse of alcohol. 

Alcoholism in Germany was a national calamity as early as the fifteenth and sixteenth centuries, when to 
the enormous consumption of beer was added that of brandy and, after 1550, of cereal and potato spirit. After 
the eighteenth century, when the production of cereal and potato spirit., became a great industry, their consump- 
tion as beverages increased enormously. In 1905 the annual expenditure for alcoholic drinks amounted to 47*. 
per head, or 8 for every person over fifteen years old, making a total of 120,000,000 for the whole of Germany, 
or about 80,000,000 for the working classes corresponding with 12 per cent, of their wages. Every year there 
are 200,000 cases of inebriety, and 75 per cent, of the crimes against the person are the result of drunkenness. 
The question of alcoholism is closely connected with the social problem, as it is especially among the working 
classes and the ignorant and ill-nourished that the victims are found. 

Abstainers are less liable to illness and usually live longer, as is shown by the following statistics. The Tables 
of the Sceptre Life Association for eleven years (1884-1894) show that the mortality in the temperance section 



ALCOHOL STATISTICS 



151 



In 1874 the average consumption of alcohol per inhabitant in Italy amounted to 
6-5 litres, and hi 1898 to 10-23 litres, to which must be added about 100 litres of wine. 1 

In Italy the production was 80,000 hectolitres in 1878 ; 165,000 in 1888 ; 187,000 
in 1898-9 ; 306,700 in 1904-5, 90,000 being from cereals, 72,600 from molasses, 
59,000 from wine, 83,000 from vinasse, and 1725 from fruit. In 1907-8 Italy produced 
463,000 hectolitres and exported 64,000 in 1908 (half in bottles) ; 134,000 in 1909, 40,000 
being in bottles and 7000 sweetened or rendered aromatic for beverages, and 95,000 
in 1910. 

In 1903 there were 3275 distilleries in Italy employing 8670 workmen. In 1904-5 
spirit factories consumed 234,000 quintals of maize, 6000 of durra, and 17,000 of barley, 
rye, millet, and rice ; also 280,000 quintals of molasses and sugar and 53,000 of other 
materials. To these must be added 575,000 hectolitres of wine, 2,600,000 quintals of 
vinasse, and 13,700 of fruit. 

In Germany 80 per cent, of the alcohol comes from potatoes (the cultivation of which 
occupies 3,300,000 hectares out of a total area of 26,000,000 hectares capable of cultiva- 
tion) ; in Austria 60 per cent., in Russia 50 per cent., and in France 20 per cent. ; the rest 
is obtained from cereals and saccharine products. 

The origin of the alcohol produced in France is as follows, the numbers representing 
hectolitres : 





From starchy 
matters 


From 
molasses 


From 
beetroot 


From 
wine 


From 
cider 


Total 


1877 . . 


163,204 


642,709 


272,883 


157,570 


9,468 


1,308,881 


1885 . 


567,768 


728,523 


465,451 


23,240 


- 20,908 


1,864,514 


1897 . . . 


484,637 


734,819 


798,484 


83,719 


26,579 


2,208,140 


1901 . 


269,074 


1,006,933 


578,628 


330,966 


115,220 


2,437,964 


1904 . 


380,710 


626,722 


992,149 


88,509 





2,181,362 














f about 


1908 . 


362,500 


448,000 


1,260,000 


468,000 


~ 


\ 2,600,000 



In Italy the tax for manufacturing alcohol was 21s. per hectolitre at 100 per cent, in 
1871, 4 in 1883, 6 in 1885, and 7 4s. in 1887 ; to this the sale-tax of 2 8s. was added 

(abstainers) was 57 per cent, and that in the general section (non-abstainers) 81 per cent. In times of epidemics 
nine out of ten non-abstainers die and only two out of ten abstainers. 

The introduction of the alcoholic tendency into Africa, as a result of colonisation, wrought such havoc qmong 
the natives that the International Congresses against Alcoholism held in Brussels in 1899 and 1906 adopted various 
prohibitive and fiscal measures to save the black race of Africa from the terrible plague. Many remedies for 
alcoholism have been proposed, but singly they are almost all inefficacious, though more useful if combined. 

Increase of the price of drinks and diminution of the number of shops have proved almost useless in France, 
Belgium, and England. In England, however, the latest increase in taxation has diminished by one-third the 
consumption of spirit ; the amount of beer has fallen from 31-4 to 25-8 litres per head per annum, whilst the 
consumption of tea and wine has increased. In the United States the enormous taxes on alcohol have not 
diminished the consumption of liquors. Sweden has obtained good results by making a State monopoly of alco- 
holic drinks, by granting licence to sell only to trustworthy persons, by giving them special facilities for, and 
large profits on the sale of other beverages and of food, by abolishing profit on alcoholic drinks and by making 
the licencees responsible for cases of drunkenness on their premises. This example has been partially followed 
in America and England, and many temperance associations have helped by opening establishments where good 
food and drink are obtainable at low prices, alcohol being banned. Another effective factor against alcoholism 
is education and the explanation of the harm done by it : in schools, churches, barracks, the streets, workshops, 
books, reviews, newspapers, 'advertisements indeed everywhere should an intelligent campaign be waged against 
alcoholic liquor which, as Gladstone said in the House of Commons, commits more slaughter in our days than the 
three historic plagues : famine, pestilence, and war, since it decimates more than famine and pestilence and kills more 
than war, and is in all cases a disgrace often lowering man below the level of the brute. 

1 The average annual consumption per head in litres of absolute alcohol in the form of different beverages 
is as follows : 



Germany 
Austria-Hungary 
France . 
England . 

Belgium . 

Denmark 
Sweden . . 
Russia . 
United States . 
Italy 



Beer 
4-8 
1-7 
1-3 
8-3 
8-7 
2-6 
2-3 
0-2 
3-4 
0-1 



Wine 
0-66 
2-1 

17-5 
0-2 
0-6 

0-06 

0-28 
12-0 



Spirits 
4-1 
5-1 
3-5 
2-3 
3-7 
7-0 
3-9 
2-5 
2-7 
2-0 



Total 

9-5 

8-9 

22-3 

10-8 

13-0 

9-6 

6-26 

2-7 

6-38 

14-1 



In Sweden 27 litres of alcohol in the form of spirits were consumed per inhabitant in 1830. 



152 



ORGANIC CHEMISTRY 



in 1888 (so that the consumer paid about 23 pence per litre in taxation alone !) ; the 
sale-tax was abolished in 1904. A rebate of 90 per cent, of the tax is made on exported 
alcohol (added to marsala, vermouth, &c.). In 1903 alcohol obtained by distilling wine 
and vinasse and destined for industrial use was exempted of all taxation, and to alleviate 
the crisis in the wine industry it was proposed, but in vain, to grant a substantial bounty 
to the distillers of wine and vinasse. In 1911 the tax was raised to 10 16s. per anhydrous 
hectolitre at 15-56. In 1910 the Italian exchequer received nearly a million sterling 
in alcohol taxes. 

In Germany the manufacturing tax of ordinary non-denatured alcohol varied prior 
to 1909 from 64s. to 72s. per hectolitre, this being entirely repaid on exported alcohol, 
which in certain cases also enjoyed a bounty of 9s. Before 1909 the tax was based on 
the volume of the wort, so that all distillers tried to work with concentrated worts (up 
to 25 Brix). Nowadays the payment is made on the volume of anhydrous alcohol 
produced, and the tax varies according to the production, which is established every 
ten years for each factory (contingent production). On this contingent quantity the tax 
is 105 marks (shillings) per anhydrous hectolitre, excess production paying 125 marks. 
There are then supplementary taxes of 4 to 14 marks to protect the small factories, so that 
a hectolitre of alcohol, costing of itself 28s. to 32s., with taxes, costs 7 4s. to 8 8s. The 
German Government received about 8,000,000 in alcohol taxes in 1908-9 and expect 
in the future to raise this to 14,000,000 ; but increase in the taxation has been followed 
by a diminution of 25 per cent, in the consumption. Potato spirit is made in 6400 large 
factories, that from cereals in 730 large and 6600 small factories, that from molasses in 
27 special distilleries, and that from wine, fruit, and yeast by about 60,000 small dis- 
tilleries. In Germany, besides the concession of untaxed denatured alcohol to all indus- 
tries, non-denatured alcohol is also allowed free of taxes to scientific laboratories and for 
medicinal uses and military explosives. The alcohol of spirituous beverages imported 
into Germany pays a Customs tax of about 14 16s. per quintal. In England the spirit 
duty amounted to about 30,000,000 in 1907. 

In Prance alcohol for drinking pays a tax of 10 per hectolitre, whilst industrial spirit 
is untaxed (as in Germany), and is sold at about 4-5 pence per litre. 

Denatured Alcohol. In several countries denatured alcohol is allowed free of tax to 
manufacturers, and in Italy in 1903 this spirit was taxed 12s. per hectolitre (100 per cent.) 
instead of 8 (which is subject to 25 to 40 per cent, bonus if made from vinasse or wine). 
Denaturation is, however, allowed only for the manufacture of ether, collodion, mercury 
fulminate, varnishes, photographic papers, artificial silk, and alcohol for heating or 
illuminating purposes. In 1905 Italy also abolished the tax of 12s. for denatured alcohol 
of whatever origin (cereals, vinasse, &c.), but there remains the cost of the denaturant, 
which sometimes amounts to 2s. Qd. or more per hectolitre for about 3 per cent, of de- 
naturant composed of methylene, acetone, pyridine, and benzene. 

In order that alcohol intended for various industries may not be used for beverages 
(wines, liqueurs, &c.), the Government denatures it by the addition of various substances 1 
stinking, coloured, or of unpleasant taste which cannot be separated from the alcohol 





DENATURANTS 




Crude 
wood spirit 


Crude 
pyridine 


Acetone 


Benzene 


Crude 
benzine 




per cent. 


per cent. 


per cent: 


per cent. 


per cent. 


France . . 


7-5 





2-5 





o-r. 


Germany . . 


1-5 


0-5 


0-5 


__ 





,, (motors) 


0-75 


0-25 


0-25 


2-0 


. 


Austria . 


3-75 


0-5 


1-25 





. 


,, (motors) 


0-5 


traces 


traces 


2'5 





Russia 


10-0 


0-5 


VO 


. 





Switzerland 


5-0 


0-32 


2-2 









In the United States methyl alcohol and pyridiue are used, and, for special purposes, ether, cadmium iodide, 
ammonium iodide, &c. 

In France denaturation costs about 10 fr. (8s.) per hectolitre, and the Government makes a rebate of 9 fr. 
In Germany it costs only 2 marks (shillings) since much less, although sufficient, denaturant is added. In Italy 
denaturation is possibly excessive and too expensive. 



DENATURED ALCOHOL 153 

by any of the ordinary means (distillation, &c.), but which do not damage the alcohol 
for its industrial use. The denaturant should vary according to the use to which the 
spirit is to be put. There are hence in all countries a general denaturant for alcohol as 
fuel, for motors, &c., and special denaturants. As colouring- matter, traces of crystal 
violet (hexamethyl-p-rosaniline hydrochloride) are used in Germany. Alcohol intended 
for the manufacture of ether, collodion, and artificial silk is denatured by the addition 
of ether and sometimes of a little acetone ; in Italy, for varnishes, 2 per cent, of methylene, 
2 per cent, of light acetone oils, and 20 per cent, of a 50 per cent, solution of sealing-wax 
are used. It has also been proposed to use part of the stinking products obtained on 
distilling certain bituminous shales. 

In 1906-7, 41,000 hectolitres of alcohol were denatured in Italy with the general 
denaturant for fuel, motors, lighting, &c. (16,790 in 1903-4, about 18,500 in 1904-5, 
over 30,000 in 1905-6, and almost 83,000 in 1910), 1031 hectolitres for making ether 
(about 1100 in 1904-5 and 8120 in 1910), 38 hectolitres for collodion (63 in 1910), 130 
hectolitres for the manufacture of mercury fulminate (140 in 1910), 1625 hectolitres for 
artificial silk in 1910, 50 hectolitres for photographic paper (1910), 995 hectolitres for 
lacquer according to the Dermoid patent, and 1364 hectolitres for other lacquers (1910). 
In France 23,000 hectolitres out of a total of 1,488,000 were denatured in 1879 ; in 1901 
153,000 hectolitres with the general denaturant were used for motors and lighting, and 
98,130 hectolitres with special denaturants for chemical industries ; in 1904, 290,000 
hectolitres with the general denaturant and 133,500 hectolitres with special denaturants, 
the total production being 2,180,000 hectolitres ; in 1907, 600,000 hectolitres were de- 
natured altogether ; and in 1908, about 626,670 hectolitres 442,758 for heating and 
lighting, 12,054 for varnishes, 21,300 for celluloid, 1147 for dyes, 359 for collodion, 194 
for chloroform, 950 for tannin, 490 for chloral, 138,346 for ether, fulminate of mercury, 
and explosives, 6972 for pharmaceutical products, 587 for scientific purposes, and 1514 
for other uses. 

In the United States, 126,000 hectolitres were denatured in 1908 and 173,000 hecto- 
litres in 1909 (after the law of 1907). In 1910-1911 the United States consumed 250,000 
hectolitres of denatured alcohol. In Norway, in 1910, 400 hectolitres were denatured, 
and the consumption of spirits, which was 40,000 hetcolitres in 1874, diminished to 
15,000 hectolitres in 1910. 

In Germany, 1,400,000 hectolitres of denatured alcohol were sold in 1904-5 (1,582,000 
hectolitres in 1908), of which 36,000 were for motors (in 1903 only 24,000 hectolitres were 
used for this purpose, 12,500 horse-power being developed). 1 In 1909-1910, 1,883,000 
hectolitres of alcohol were denatured in Germany. 

Denatured 90 per cent, alcohol now costs 465. per quintal in Italy, whilst in Germany 
it costs only about half this, namely, 25 marks (shillings) per hectolitre (after 1909, with 
the new tax, 48s.), in Austria 26s., in Switzerland 24s. (retail), and in Belgium 25s. 

UTILISATION OF DISTILLERY RESIDUES. All the components of the prime 
materials used in the production of alcohol are found (excepting the carbohydrates : 
starch and sugar) in the residues (grams, spent wash) left after the distillation of the 
alcohol. 

These residues formerly formed inconvenient refuse, since they readily undergo putre- 
faction and, if discharged into rivers or canals, contaminate the water. In exceptional 
cases, when the distilleries are in large agricultural centres, the residues are used in 
the wet state for cattle-food, but more commonly they are evaporated and dried, these 
dried grains being highly valued as a concentrated fodder, rich in proteins 2 and having 
a restricted (1 : 3 to 1 : 5) nutritive ratio (ratio between nitrogenous and non -nitrogenous 
substances). 3 In the fresh residues two-thirds of the part which is not water is dissolved 

1 An automobile weighing 1200 kilos, on a journey of 174 kiloms. (109 miles) at 30 kiloms. (19 miles) per 
hour, consumed 11-3 litres of alcohol ; under similar conditions, 10 litres of petrol are required. For an 8 h.p. 
car, 350 grms. of alcohol or 500 of petrol are used per horse-power hour. For automobiles and explosion 
motors in general, the Paris Omnibus Company uses alcohol mixed with 50 per cent, of benzene, this giving a 
better thermal efficiency (34 per cent.). A domestic 25-candle lamp with an Auer mantle uses about 2 grms. of 
alcohol per candle-hour. The use of alcoholene, a mixture of alcohol and ether, has now been proposed, and 
from a technical standpoint presents advantages over alcohol and other mixtures. 

* The average percentage compositions of the principal residues will be found in the Table on page 154. 

3 For fodder, the nutritive values of the proteins, fats, and non-nitrogenous digestible substances are in the 
proportions 3 : 2 : 1, so that the commercial value of a fodder, expressed in nutritive units, is given by : nitrogenous 
substances x 3 -f fatty substances X 2 + non-nitrogenous substances, given by the percentage composition 
of the digestible components. 



154 



ORGANIC CHEMISTRY 



and the remaining third suspended in the water. Potatoes give about 10 per cent, of 
dried residue, malt about 40 per cent., and maize 45 to 50 per cent. 

It will hence be understood how distilleries have greatly increased the raising of cattle 
and consequently production of stable manure, thus contributing to the fertilisation of 
formerly unfertile lands. 

The economics of the drying of these residues has always constituted a difficult problem 
owing to the presence of more than 90 per cent, of water in which part of the nutritive 
products is dissolved and to the fact that the dried residues sell at 8s. to 11s. per quintal. 
In many cases the liquid portion is abandoned and the solid part separated by filter- 
presses or centrifuges ; but if the liquid part cannot be got rid of, even after addition 
of lime, ferrous sulphate, &c., it is best to evaporate it by means of the hot fumes from 
the flues, the operation being hastened with disc-stirrers of large surface and with fans. The 
evaporation is sometimes carried out in a vacuum apparatus (see Sugar) furnished with 
stirrers, by which means a marked economy in fuel is effected (see also vol. i, pp. 442- 
444). 




FIG. 149. 

Of the various drying systems (Hatschek, Meeus, Porion and Mehay, Venuleth and 
Ellenberg, Theisen, Biittner and Meyer, &c.), we shall only deal with that of Donard and 
Boulet, which has been applied with advantage in France and recently also in Italy. 

The solid residue from the filters or centrifuges (perhaps mixed with the evaporated 
residue of the liquid portion), still containing more than 50 per cent, of water, is carried 
by mechanical transporters into the vacuum drying apparatus (Fig. 149), consisting 
of a horizontal cast-iron cylinder rotatable about a hollow axis through which the steam 
enters or issues ; its length and diameter are 2-5 metres. Inside are a number of tubes 
(heating area about 60 sq. metres) into which steam is passed from D, the condensed 
water being discharged without coming into contact with the mass to be dried. At the 

TABLE OF AVERAGE PERCENTAGE COMPOSITIONS OF THE PRINCIPAL RESIDUES 





Beetroot 


Potato 


Rye 


Maize 


Durra 


Barley 




liquid 


dried 


liquid 


dried 


liquid 


dried 


liquid 


dried 


liquid 


dried 


liquid 


dried 


Water . 


91-0 


10-12 


94-0 


8-10 


91-0 


10-12 


90-6 


10-12 


90-3 


10-12 


75-0 


14-0 


Proteins 


0-9 


6-7 


1-3 


18-24 


1-9 


22-28 


2-0 


24-26 


2-0 


24-26 


4-0 


20-0 


Non-nitrogenous 


-\ 
























matter 


I 7-2 


60-65 


2-6 


45-55 


5-2 


48-52 


4-9 


35-40 


5-1 


30-34 


10-0 


46-0 


Fatty matter 


( 


1-3-1-6 


0-2 


3-4 


0-3 


5-6 


1-0 


12-16 


0-7 


12-14 


1-7 


7-0 


Cellulose 


> 


13-15 


0-9 


9-11 


1-0 


5-7 


1-0 


10-12 


1-1 


14-16 


5-0 


16-0 


Ash 




10-12 


0-5 


1-2 


0-6 


4-6 


0-5 


5-6 


0-8 


7-8 


1-3 


5-0 



ALCOHOLIC BEVERAGES: WINE 155 

other end, by means of the perforated axis, G', the interior of the cylinder communicates 
with a double-action exhaust pump to carry away the vapour from the grains which are 
hsated in a vacuum of 700 mm., while the cylinder slowly rotates (three turns per minute). 
The charge consists of 25 to 30 quintals of solid grains, which are dried (to 15 per cent, 
moisture, it then keeping well) in less than four hours, the coal consumption being about 
150 kilos. By thus drying at a relatively low temperature (in a vacuum) and out of 
contact with air, the oil of the grains does not become rancid. 

Since maize-grains contain as much as 15 to 18 per cent, of fat, it is sometimes' 
convenient to extract them in one of the forms of apparatus described in the section 
on Fats. 

Special interest attaches to the residues from Molasses and Beet, since these contain 
special nitrogenous compounds (amino-acids) and a large proportion of potassium salts 
utilisable for fertilisers or for chemical products. The evaporation of the liquid part of 
these residues may be carried to a certain stage in the ordinary vacuum plant, the mass 
being subsequently completely evaporated and the residue calcined in suitable furnaces 
(Porion model in France and Belgium) which are similar to the reverberatory furnaces 
or muffles used in the preparation of sodium sulphate (see vol. i, p. 161). Care must 
be taken not to fuse the mass, which, when discharged, should still be carbonaceous and, 
indeed, sufficiently so to cause it to burn when placed in heaps outside the furnaces ; the 
greyish mass thus obtained known in France as salin contains : water, 0-3 to 6 per 
cent. ; KC1, 6 to 10 per cent. ; K 2 SO 4 , 10 to 14 per cent. ; potassium phosphate, 0-5 to 1 
percent. ; K 2 C0 3 , 53 to 58 per cent. ; Na 2 CO 3 ,6to 9 per cent. ; soluble substances, 9 to 
14 per cent. By this treatment, however, all the nitrogen compounds are lost ; but in 
some cases these are used for the extraction of methyl chloride (see p. 96). The process 
for extracting pure potassium carbonate, ammonia, and sodium cyanide is referred to 
in vol. i, p. 435. 

During recent years the utilisation of these nitrogenous substances has assumed great 
importance : according to the Effront patents (1907), the amino-acids are utilised by 
enzymic processes 1 for the preparation of organic acids and ammonium sulphate (with 
each hectolitre of alcohol produced correspond 25 kilos of ammonium sulphate and 
35 grms. of organic acids, principally acetic, propionic, and butyric). Since 1902, the 
Dessau Sugar Refinery, and since 1904 the Ammonia Company of Hildesheim, have 
utilised the nitrogen compounds as potassium cyanide and ammonium sulphate. In 
1907 the Ammonia Company utilised 60 per cent, of the nitrogen of the residues, 
producing potassium cyanide to the value of 80,000 and ammonium sulphate to the 
value of 20,000. 

ALCOHOLIC BEVERAGES 

WINE. Only the liquid obtained by the spontaneous alcoholic fermentation of the 
must of fresh grapes, without any addition, should be called wine. The fermentation 
i^ spontaneous owing to the presence on the grapes of Saccharomyces cerevisice. 

Grape must has the sp. gr. 1-08 to 1-10 and contains 70 to 86 per cent, of water, 16 to 36 per 
cent, of sugar (glucose and levulose, which reduce Fehling's solution) ; 1 to 3 per cent, of 
cream of tartar, tartaric, malic, and tannic acids ; 0-4 to 1 per cent, of colouring, aromatic, 
extractive, gummy, and protein substances, and mineral salts. If the musts have to 
be transported over long distances, either they are concentrated in a vacuum or by freezing, 
or the fermentation is interrupted for a time by filtering them. One quintal of grapes 
gives 60 to 70 litres of must and 30 to 35 kilos of residue (marc). 

By fermentation in open vats the sugar is transformed, more or less completely, in 
7 or 8 days into alcohol, large quantities of carbon dioxide being developed and 
a little glycerol, succinic acid, &c., always being formed. With more than 25 per cent, 
of sugar, sweet wines are obtained, and with less, dry wines. Fermentation cannot yield 
more than 15 to 16 per cent, of alcohol, as with more than this proportion the yeast dies. 
After the principal fermentation, when the wine, without the marc, is placed in casks 
of chestnut or oak, a slow fermentation goes on, this ceasing in the winter ; with increase 
in the alcohol -content and lowering of the temperature, the yeast and part of the tartar 

1 Ehrlich was the first to show that the fermentation of amino-acids is produced by amidages. Effront (1908) 
found that amidases occur especially in top beer-yeasts and in aerobic yeasts which, in seventy-two hours at 40" 
are able to transform, e.g. all the nitrogen of an alkaline asparagine (fee this) solution, and almost all the nitrogen 
of the yeast itself into ammoniacal nitrogen, organic acids being formed at the same time. 



156 ORGANIC CHEMISTRY 

(slightly soluble in alcoholic liquids) are deposited. In the spring, the clear wine is 
decanted into clean (sulphured?) casks, which are kept full. It can now be placed on 
the market, or it can be further matured by clarifying it in the cask (by shaking with 
albumin and a little tannin and allowing to stand) and by decanting and filtering it several 
times during the course of a year or more before placing in well -cleaned bottles ; the 
latter are corked by machinery with paraffined corks. As time goes on, the wine acquires 
a pleasing aroma, this process being hastened sometimes by pasteurisation, which consists 
in passing the wine rapidly through coils heated to about 60 ; this process ako arrests 
certain incipient diseases, which would otherwise end by spoiling the wine (acidity, &c.). 
Sparkling wines are obtained by saturating the cold wine with carbon dioxide during 
bottling or by bottling sweet wines, the fermentation of which continues slowly in the 
corked bottle ; in the latter case, however, a deposit forms at the bottom of the bottle. 

In order to obtain wines of constant type on a large scale, co-operative wineries have 
been recently instituted in France, these collecting the grapes or must from a whole 
district, mixing it and preventing it from fermenting by saturating it in the cold with 
sulphur dioxide (70 grms. liquid SO 2 per hectolitre) ; in this way, not only the yeasts, 
but also the moulds, bacteria, and unpleasant odours are destroyed and the must can 
then be kept for months in closed vessels. When part of the must is to be converted 
into wine, it is heated at 50 to 60 in a vacuum by allowing it to pass down a kind of recti- 
fying column (Barbet, Ger. Pat. 195,235, 1906), the sulphur dioxide thus removed being 
recovered ; selected yeast or other wine rich in yeast is then added, the resulting wines 
being of uniform and improved character, although somewhat rich in sulphates. These 
desulphurated musts might well be used as non-alcoholic wines. There are also special 
yeasts capable of destroying SO 2 in the musts and of starting fermentation. In Italy 
much has been said in favour of co-operation in 1909 and 1910, but no trial has been 
made on a large scale. 

The proportions of the most important components of wine vary between wide limits, 
owing to variation of the vines, soil, climate, system of wine-making, and season (certain 
wines contain manganese, sometimes as much as 27 mgrms. per litre). 

It is hence difficult to ascertain if there has been an artificial addition of constituents 
similar to those naturally present in the wine, so that considerable dilution with water and 
addition of alcohol, glycerol, tartar, sugar, &c., are not easy to detect if they do not 
exceed such limits. Natural wines may contain 8 to 16 per cent, of alcohol, 1-6 to 4 per cent, 
(for dry wines, and as much as 20 per cent, or more for sweet wines) of dry extract 
(obtained by evaporating a definite volume to dryness on a water-bath and drying in 
an oven at 100), 0-5 to 1-5 per cent, of various acids and tartar (expressed as tartaric acid) 
and 0-15 to 0-45 per cent, of mineral substances (ash, obtained by calcining the dry extract) ; 
the glycerol varies from one-seventh to one -fourteenth part of the alcohol. Naturally 
these variations are much smaller for wines of a certain quality and year and obtained 
from one and the same district, for which the results of numerous analyses have been 
collected. 

In Italy the following minimum legal limits have been recently (Ministerial Circular, 
1907) established as those which must be reached for a wine to be called natural (except 
in cases where genuine, wines of the same origin and year are shown to give lower limits) : 
alcohol, 8 per cent, by volume in white wines, 9 per cent, in red ; dry extract without sugar, 
1-6 (white), 2-1 (red) ; total acidity expressed as tartaric acid, 0-5 (white), 0-6 (red) ; 
ash, 0-15 (white), 0-2 (red) ; alkalinity of the ash in c.c. of normal alkali per litre, 11 
(white), 16 (red) ; the glycerol should be from one-seventh to one-fourteenth by weight 
of the alcohol, and the relation between ash and extract (for dry wines or for sweet wines 
after deducting the sugar) should be about 1 : 10 ; plastering, 1 expressed as sulphuric 
acid, should not exceed 0-02 per cent. 

In France, and now also in Italy, watering of a wine is detected by adding the per- 
centage of alcohol by volume to the total acidity per litre expressed as sulphuric acid ; 
this should give 13-5 for red and 12-5 for white wines (in Milan, 12-5 is allowed for red 
and 11-5 for white wine). Wines weak in alcohol or tartar do not keep well in the warm 

1 In order to prevent certain diseases to which southern wines low in acidity are liable, recourse is had to 
plastering, i.e. the addition of sulphites or bisulphites, which increase the quantities of sulphuric acid and sulphates. 
Thus some wines remain clear in the bottle, but become turbid and dark on exposure to the air ; this disease, 
termed casse, is prevented by addition of potassium bisulphite, which also arrests secondary fermentation. 
To make certain weak wines keep better in summer in tapped casks, calcium sulphite is added, this giving a slow 
evolution of sulphur dioxide. 



TESTING OF WINE 157 

weather. A weak wine can be improved by either mixing with stronger wines or con- 
centrating by freezing, water then separating in the form of ice (this method, in use even 
in the Middle Ages, has recently been patented in Italy !) 

New wine has sometimes the smell and taste of rotten eggs, i.e. of hydrogen sulphide ; 
this can be remedied by decanting it into casks in which sulphur has been burnt : 
2H 2 S + S0 2 = 2H 2 + 3S. 1 

From the vinasse remaining after the wine is drawn off a little rather rougher wine 
can still be obtained by subjecting it to considerable pressure, and from the pressed vinasse 
alcohol (see above) and tartar (see later) can be extracted. 

The testing or analysis of wine is usually limited to determining the alcohol (by the 
method described on p. 146), dry extract, ' ash (see above), glycerol, plastering, and 
total acidity, and to testing for the addition of colouring -matter and other adultera- 
tions. 2 

Statistics. The countries which produce the most wine are France, Italy, and Spain. 
For Italy the statistics are very contradictory, and even the official ones are erroneous ; 
for instance, the production for 1909, which was given officially as 40,000,000 hectols. 
was officially corrected in 1910 to 60,000,000 hectols. 

1 To desulphur musts and wines, use is sometimes made of a small quantity of urotropine (hexamethylene- 
tetramine) ; such addition can be detected, according to Fonzes-Diacon and Bouis (1910) by distilling 25 c.c. 
of the wine with 3 drops of sulphuric acid, acidifying the first 5 c.c. of distillate with 1 c.c. of sulphuric acid, and 
observing if it colours a solution of fuchsine decolorised with sulphur dioxide. The residue from the distillation 
is rendered alkaline with magnesium hydroxide and distilled, the vapours distilling over being condensed in a 
known volume of N/10 sulphuric acid, which is titrated back to ascertain how much ammonia distils over from 
the urotropine. 

1 The Total Acidity is estimated by titrating 10 c.c. of the wine, diluted with water, with N/10 sodium hydroxide 
solution, using blue litmus paper as indicator ; multiplication of the number of c.c. of NaOH by 0-75 gives the 
total acidity in 100 c.c., expressed as tartaric add. A volatile acidity (acid that distils in a current of steam) 
exceeding 0-1 per cent., expressed as acetic acid, indicates a sour wine. 

The Cilycerol is determined by evaporating 100 c.c. of wine to about 10 c.c. on the water-bath, then adding 
sand and milk of lime until it is strongly alkaline and evaporating to dryness ; the residue is taken up in 50 c.c. 
of 95 per cent, alcohol, the solution boiled and filtered, and the residue washed with 150 c.c. of hot alcohol ; the 
filtrate is then evaporated on the water-bath to a syrup, which is well mixed with 10 c.c. of absolute alcohol and 
15 c.c. of ether, allowed to deposit, filtered into a tared dish, the residue on the filter being washed with a mixture 
of equal volumes of alcohol and ether. Evaporation of the solvent leaves the glycerol, which is dried in a steam- 
oven and weighed. 

Plastering is allowed bylaw up to a maximum quantity of total sulphuric acid (of sulphates) corresponding 
with 2 grms. of normal potassium sulphate per litre. Hence, on adding to 50 c.c. of the wine, 50 c.c. of a solution 
of BaCl 2 (2-8 grms. of the crystallised salt and 50 c.c. of HC1 to a litre), boiling, allowing to stand, and filtering, 
the filtrate should give no further precipitate with barium chloride solution, that already added being exactly 
sufficient to precipitate the maximum allowable amount of potassium sulphate. Excessive sulphuration of wines 
is sometimes masked by the addition of urotropine (see above), which decomposes into ammonia and formal- 
dehyde, the latter fixing the sulphurous anhydride ; this can, however, be detected by Schiff's reaction (see 
Aldehydes). 

Artificial Coloration. 100 c.c. of the wine are evaporated to about one-third the volume, 3 to 4 c.c. of 10 per 
cent. HC1 and 0-5 grm. of well defatted white wool being then added and the liquid boiled for five minutes ; the 
solution is then poured off, and the wool, after being thoroughly rinsed in running water, is repeatedly boiled 
with fresh quantities of water acidified with HC1 until the latter no longer becomes coloured ; the wool is again 
well washed with water and boiled for ten minutes with 50 c.c. of water and 15 to 20 drops of concentrated 
ammonia solution, the wool being then removed and the boiling continued to expel the ammonia ; the liquid is 
then slightly acidified with HC1 and boiled for five minutes with fresh wool. If the latter, after washing, 
remains distinctly red, the presence of artificial coal-tar colours in the wine may be certified ; but if the colour 
of the wool is faint or indefinite, the colour is removed with water and ammonia, and the solution acidified and 
boiled with fresh wool ; even a faint red coloration of this confirms the presence of coal-tar dye. 

L. Bernardini (1910) finds that if the lower end of a strip of filter-paper is dipped into wine coloured with 
vegetable or animal substances, these rise to a greater height than the cenocyanin, which is more tenaciously 
fixed ; hence, after the paper has been dried, different parts can be tested for artificial colouring-matters by the 
characteristic general reactions (see Table of Colouring-Matters in Part III). 

It has been observed recently that the natural colours are slowly decolorised (in 48 hours) by hydrogen 
peroxide, whilst the artificial ones are not, 

Salicylic Acid and Saccharin are detected as in beer (see later). 

Added water is difficult to recognise if it does not bring the constituents of the wine below the legal limits 
(see above), and sometimes as much as 40 per cent, of water can be added to strong wines without reaching these 
limits. However, since natural wines never contain nitrates, which are present in almost all waters, the following 
test may be made : 100 c.c. of the wine are treated with 6 c.c. of lead acetate solution and filtered. To the filtrate 
are added 4 c.c. of concentrated magnesium sulphate solution and a little pure animal charcoal, the liquid being 
shaken, allowed to stand a short time, and then filtered. To a few drops of the decolorised liquid are added a 
few crystals of diphenylamine and 1 to 2 c.c. of concentrated sulphuric acid. If a blue coloration is formed, the 
presence of nitrates is demonstrated the reagents being assumed to be pure. If the wine is watered with distilled 
or condensed water, or pure rain water, the reaction for nitrates is not given. 

The addition of Glucose to wine or liqueurs is detected by adding to the wine a little pure yeast (pressed yeast) 
so as to ferment completely any grape-sugar still present as well as the added glucose. Commercial glucose, 
prepared from starch, always contains a small quantity of unfermentable, dextro-rotatory substances, so that 
if the wine, after fermentation is complete (when no more CO, is evolved) and after decolorisation with animal 
charcoal or with a little lead acetate, still exhibits a dertro-rotation greater than 0-5" in a 20 cm. tube, the presence 
of, glucose is proved. 



158 ORGANIC CHEMISTRY 

The following figures represent hectolitres (1 hectolitre = 22 gallons) 





France. 


Italy 


Production 


Production 


Exportation 


1875 


83,000,000 


28,000,000 


363,000 


1879 


25,000,000 


34,000,000 


1,075,000 




(phylloxera) 




* 


1884 


34,781,000 


21,000,000 


2,380,000 


1887 


24,333,000 


34,000,000 


3,603,000 (2,800,000 to France) 


1889 


23,000,000 


22,000,000 


1,440,000 (commercial treaty with France 








broken in 1887) 


1893 . 


59,000,000 


32,000,000 


2,362,000 (750,000 to" Austria-Hungary ; 








300,000 to Switzerland, 1 and 








426,000 to America) 


1897 


32,000,000 


28,000,000 


2,400,000 


1901 


58,000,000 


44,000,000 


1,334,000 


1902 





35,000,000 


2,164,000 (976,300 to Austria-Hungary). 


1903 


39,000,000 








1904 





42,000,000 


1,200,000 (Austro -Hungarian market lost 








by new commercial treaty) 


1905 


57,000,000 


28,000,000 


980,000 (worth 1,400,000) 


1906 


62,000,000 


30,000,000 


710,000 


1907 


66,070,000 


54,000,000 


920,000 


1908 


66,500,000 


52,000,000 


1,200,000 


1909 


66,000,000 


60,000,000 


1,450,000 (France has a vine area of 1,625,630 








and Italy of 3,500,000 hectares) 


1910 





42,000,000 


2,000,000 



In the Italian exportation is included that of marsala, vermouth, and bottled wine, 
this amounting in 1885 to 1,200,000 bottles and flasks (including vermouth and marsala), 
in 1894 to 3,000,000, in 1897 to 4,720,000, in 1904 to 8,120,000, and in 1905 to 9,000,000 
(worth 440,000), whilst in 1891 France exported 33,000,000 bottles (worth 3,800,000) 
and to-day has an enormous export. 

The world's 'production of wine in 1902 was 126,000,000 hectolitres: 16,000,000 in 
Spain, 5,200,000 in Austria, 2,000,000 in Hungary, 5,000,000 in Portugal, 3,500,000 
in Algeria, 2,000,000 in Germany (formerly 3,700,000 ; in 1906 1,636,000 and in 1907 
2,492,000 from 118,600 hectares of vineyards, in 1910 846,139 hectolitres), 2,300,000 in 
Russia, almost 2,000,000 in Turkey and Cyprus, nearly 1,000,000 in Greece and its islands, 
2,300,000 in Bulgaria, 2,700,000 in Roumania, 500,000 in Servia, 1,100,000 in the 

1 The following is a statistical resume of the wine imported into Switzerland from 1906 to 1910 (in 
hectolitres) : 



From 


1906 


1907 


1908 


1909 


1910 


Italy . i, 


137,843 


300,208 


531,776 


651,726 


828,559 


France 


273,731 


581,163 


363,769 


386,486 


216,909 


Spain 


123,587 


219,666 


415,052 


352,347 


422,775 


Austria 


53,411 


78,104 


69,634 


91,034 


110,608 


Greece 


9,370 


10,120 


12,209 


42,234 


64,874 


Algeria-Tunis 


19,520 


52,501 


17,342 


11,118 


10,714 


Germany 


10,009 


8,870 


7,619 


7,650 


5,504 


Turkey . . 


5,743 


5,183 


3,637 


2,865 


2,451 


Other countries 


50 


50 


62 


457 




Total hectolitres 


633,566 


1,255,865 


1,421,290 


1,546,027 


1,675,427 


Total value . . 








"^ 


1,430,800 


2,255,840 



VARIOUS WINES, ETC. 159 

United States, 1,500,000 in Argentine, 2,500,000 in Chili, 350,000 in Brazil, 327,000 
in Australia, &c. The total production in 1909 was estimated at 160,000,000 hectolitres. 
The average annual consumption per head is 144 litres in France, 121 in Italy, and 116 
in Spain. In Milan in 1909 duty was paid on 1,000,000 hectolitres, the Corporation 
receiving 420,000, and the consumption per head being 200 litres. 

In 1905 Italy exported to Germany 124,000 quintals of dessert grapes, whilst France 
exported only 78,000 quintals. In 1892 Italy exported about 260,000 hectolitres of 
wine to Germany, but less amounts in subsequent years. 1 

MARSALA. This is a liqueur wine made for the first time at Trapani in 1773 by 
J. Woadhouse of Liverpool to compete with the world-famous Madeira. In 1812 another 
large establishment was started by the Englishman, Benjamin Ingham, and in 1840 
Vincenzo Florio's factory which has since become the most celebrated. The prime 
material for the manufacture of Marsala is white Trapani wine with 13 per cent, of alcohol, 
to which is added (in quantity varying for different types of Marsala) the must (cotto) of very 
mature white grapes, concentrated in open boilers until two-thirds have evaporated ; 
then is added, in varying amount, the sifone, obtained by filling a cask to the extent of 
three-fourths with clear, must from a very ripe white grape, and one-fourth with pure 
alcohol (free from tax if for export), mixing and allowing to age so as to develop the 
Marsala aroma. 

Mixtures of these three components in different proportions give the various brands 
of Marsala : the Italian brand is the least alcoholic (16 to 17 per cent.) ; the original English 
brand, the strongest (up to 24 per cent, of alcohol) ; while the Margherita and Garibaldi 
brands are of intermediate strengths and are sweeter, 

In 1904 Italy exported in cask 30,540 hectolitres of Marsala, worth 92,000 ; in 
1905,29,765 hectolitres, worth 83,280, and 51,000 bottles, value 2040 ; in 1906,26,800 
hectolitres ; in 1907,27,677 hectolitres ; in 1908,24,900 hectolitres ; and in 1909,24,800 
hectolitres, of the value of 97,600, together with 136,000 bottles. In 1910 the exportation 
was 32,500 hectolitres. 

VERMOUTH. This was prepared formerly in Tuscany, but nowadays almost 
exclusively in Piedmont, where the industry was started in 1835 by Giuseppe Cora and 
A. Marendazzo. 

The prime material for manufacturing vermouth is the muscat wine of Asti and of 
the Monferrato heights, which contains 6 to 11 per cent, of alcohol and 2 to 4 per cent, of 
sugar ; with this is mixed 2 to 5 per cent, of a vinous infusion of aromatic drugs in which 
wormwood predominates and which contains also sweet flag, juniper, gentian, &c. ; 
finally alcohol is added to bring the strength up to 15 to 18 per cent, and sugar to the density 
of 6 to 9 Be. (if for exportation, 90 per cent, of the alcohol and sugar taxes are refunded). 
Sparkling vermouth is made by saturating it with CO 2 in the cold under pressure. 

It cannot be said that in the manufacture of Marsala and vermouth all the rational 
methods prescribed by modern oenotechnics are followed. 

The production of vermouth in Piedmont is now about 250,000 hectolitres, the exports 
(especially to America) being 12,400 hectolitres in cask and 31,214 hectolitres in bottle 
in 1902 ; 10,000 hectolitres (24,000) in cask and 53,500 hectolitres (224,000) in bottle 
in 1905 ; 8960 hectolitres in cask and 64,980 hectolitres in bottle in 1906 ; 8600 hecto- 
litres in cask and 77,800 hectolitres in bottle in 1907 ; 7874 hectolitres in cask and 83,300 
hectolitres in bottle in 1908 ; 10,176 hectolitres in cask (27,680) and 100,000 hectolitres 
in bottle (464,920) in 1909 ; 20,400 hectolitres in cask (53,040) and 173,670 hectolitres 
in bottle (760,000) in 1910. 

CIDER. This is an alcoholic drink obtained by the partial fermentation of the juice 
of apples and pears. It is largely used in the north of France, in Germany, and in Swit- 
zerland. It is consumed almost immediately it is made. In France the production 
varies from 8,000,0000 to 30,000,000 hectolitres, part of which is distilled to produce 
alcohol (30,000 to 70,000 hectolitres of alcohol). 

LIQUEURS. These contain 40 to 70 per cent, of alcohol. The finest are those obtained 
by collecting the first, more highly alcoholic distillate from other fermented liquors. 
Such are brandy (prepared by distilling vinasse or wine and containing 45 to 55 per cent, of 
alcohol), cognac, kirschwasser (obtained especially from the cherries of the Black Forest ) f 

1 The import dutie elevied by different countries on Italian wines are as follows : Germany, 29*. per quintal ; 
Belgium 18. &d. Holland, 34*. ; England, 23s. for wines with less than 14-84 per cent, of alcohol, and 54.*. M. 
for strosger one li -. i 45s. ; United States, 54s. 6d. ; and British India, 33*. 6d. 



160 ORGANIC CHEMISTRY 

rum (prepared principally in Jamaica by distilling fermented cane-sugar molasses), 
maraschino (prepared from small Zara cherries), gin (from juniper berries), atole or chica 
of South America, arrack of the Arabs and Indians (prepared from rice, cane-sugar, and 
coco-nuts), schnapps of the Germans (potato spirit), &p. 

The other class of liqueurs comprises those obtained from aromatic substances, sugar, 
and more or less concentrated pure alcohol. In this way are obtained rosoli, anisette, 
absinthe (alcoholic decoction and distillation with wormwood) much used in France 
and the principal cause of the terrible effects of alcoholism (p. 150) creme de menthe, 
creme de cafe, &c. ; ratafia from fruit must, spirit, and sugar ; Chartreuse (the most cele- 
brated was that prepared by the Carthusian monks, before their expulsion from France 
in 1904, from balm-mint, cinnamon, saffron, hyssop, angelica, sugar, alcohol, and other 
ingredients), coca (from Bologna), curacao (first prepared from two kinds of orange in the 
island of Curasao in the Antilles), kummel (in Russia the best kinds are obtained by 
distilling brandy or alcoholic liquids with Dutch cumin seeds and dissolving pure sugar 
in the highly alcoholic distillate). It is unnecessary to mention that all liqueurs, even 
the most celebrated, are more or less poorly imitated in all countries with mixtures in 
no way resembling the original types, but the latter always command very high prices. 

Cognac is a brandy prepared especially in Charente by very carefully distilling weak 
wines of special vintages and refining and maturing the product in casks of Angouleme 
or Limousin oak, which gradually imparts to the spirit a pale yellow colour and a 
characteristic aroma. The finer and older brands sell at as much as 40 per hectolitre. 

FERMENTED MILK. This bears the following names according to the locality 
and method of its preparation and the nature of the milk from which it is made : kephir, 
koumis, galazin, leben (Egypt), and mazun. The first three of these are the best known. 

KEPHIR, or Kefir, is of very ancient origin among the Caucasian highlanders, who 
nowadays make enormous use of it and jealously keep the secret of its preparation. There 
is a legend to the effect that Allah was the first to make it, and that he recommended it 
as a remedy for various diseases. Kephir is simply cows' milk (fresh or skim) fermented 
by the addition of a special ferment in the form of granules, which the Russians call 
"fungi " and the Tartars " grain or millet of the Prophet," as they regard it as discovered 
by Mahomet. It was only in 1882 that Dr. Dmitrieff called the attention of the rest 
of Russia and of Europe to kephir and its great recuperative properties in cases of lung 
diseases. 

Kern and, later, Freudenreich showed that the alcoholic fermentation of milk with 
millet of the Prophet is due to the simultaneous action (symbiosis) of the new Saccharomyces 
kephiri (similar to ordinary Saccharomyces ellipsoideus), a streptococcus, and a bacillus. 
The alcoholic fermentation of milk-sugar with evolution of C0 2 takes place rapidly and 
is always accompanied and followed by acid fermentation (lactic acid), which partially 
dissolves the casein (propep tones) and forms a very fine coagulation, almost a frothy 
emulsion. In practice the kephir granules are softened with tepid water (30 to 35) for a 
couple of hours, the milk being then added and the mixture shaken every hour for eight 
hours ; it is then sealed up in clean bottles fitted with mechanical stoppers and is shaken 
now and then, the temperature being maintained at 15 to 20 ; in 24 hours' time 
the kephir is ready ; it forms a slightly alcoholic and acidulated dense, frothing liquid. 
If the kephir is left in closed bottles for two days, the pressure increases and the mass 
becomes more acid and more liquid ; by the third day it becomes extremely acid and 
contains up to about 2 per cent, of alcohol, and after this it is inadvisable to drink it. 

In Italy kephir or kephir-extract is placed on the market by the Borgosatollo Dairy 
(Brescia) and kephir dried in vacua is also prepared (Rosemberger, Ger. Pat. 198,869, 
1907). 

KOUMIS is similar to kephir, and of equally ancient origin, but is prepared from 
mares' milk. In Russia there are various sanatoria which make efficacious use of large 
quantities of koumis. The composition of the latter has been found to be : Water, 
94 per cent. ; CO 2 , 0-9; ethyl alcohol, 1-7; lactic acid, 0-7; lactose, 1-3 (before fer- 
mentation 5-5) ; fats, 1-3 ; proteins, 2-3 (largely peptonised) ; salts, 0-3. 

GALAZIN is obtained by placing skim (cows') milk, with 2 per cent, of sugar and 
0-3 per cent, of beer-yeast in strong, tightly stoppered bottles, and allowing fermentation 
to proceed for twenty -four hours at 16 ; from the second to the sixth day the proportion 
of alcohol rises from 0-3 to 1-5 per cent. Galazin is less nutritious than kephir or koumis. 



BREWING 



161 



BEER 

This is another alcoholic liquor saturated with C0 2 and is obtained by 
fermenting aqueous decoctions of barley-malt and hops. 

The ancient Egyptians were acquainted with the manufacture of beer and held it in 
great regard. Later it became known to the Ethiopians and the Hebrews, but the Greeks 
never acquired a taste for beer. The industry was taken by the Armenians from Egypt 
into the interior of Asia, and still later beer was manufactured in Spain and France, but 
it was never consumed by the Romans. In Germany beer has been made from time 
immemorial. 

A marked improvement in the manufacture of beer dates from the time of Charles 
the Great, when hops were first used. 




FIG. 150. 



FIG. 151. 



Lager beer (see later) was prepared as early as the thirteenth century, and its use has 
since been greatly extended in various countries. 

In England the manufacture has flourished since the fifteenth century, the famous 
porter being first made at the beginning of the eighteenth century. 

The improvements made in brewing operations by the introduction of scientific methods 
have led to a very considerable development of the industry in Germany and elsewhere. 

The prime materials for the manufacture of beer are barley, rice, maize, &c., 
hops, water, and yeast. 

LA. BARLEY 1 should satisfy the following requirements : 

1 Barley (botanical species Hordeum) used for making beer is of two types : two-rowed (Fig. 150), in which 
the corns are arranged in the ear in two rows, one on each side, and six-rowed (Fig.151), in which there are three 
rows of corns on each side of the ear. Different kinds of barley can, to some extent, be recognised by the form 
of the small basal bristle found at the base of the corn inside the longitudinal furrow. The value of barley for 
brewing purposes is largely influenced by the nature of the soil, climate, methods of cultivation, and manuring. 
Barley is cultivated in all countries and in all climatesin Holland and also in Sicily. It is difficult to keep 
II II 



162 



ORGANIC CHEMISTRY 



(a) When moistened and kept at 25 to 30, 80 per cent, of the corns should germinate 
in 48 hours and 90 to 95 psr cent, in 72 hours. 

(b) Those are preferred which are heaviest (60 to 70 kilos per hectolitre) and contain 
about 62 per cent, of starch, about 10 per cent, of protein, and 12 to 14 per cent, of moisture. 

(c) The skin should be thin and the colour pale yellow, the ends of the corns not being 
brown. 

Barley starch swells at 50, and with water forms a paste at 80. With diastase it 
begins, unlike potato starch, to saccharify as soon as it is completely transformed into 
paste. 
! B. Wheat is sometimes used, together with barley, for pale beers. 

C. Maize is used in America after being skinned and degermed, the germ being rich 
in oil. 

D. Rice is used in America and Scandinavia with the barley. 

2. HOPS. The female 
flowers, dry and mature, of 
Humulus lupulus (Fig. 152) 
are used, these containing 10 
to 17 per cent, of a powder 
(which can be separated by 
shaking and sieving) possess- 
ing the aromatic and bitter 
principles which bestow on 
the beer its aroma and keep- 
ing qualities. 1 

varieties pure, since they become 
modified during growth owing to 
crossing. Only by the rational 
system of selection initiated by Dr. 
Nilsson at the Svalof Institute is it 
possible to fix different varieties 
with constant, well-marked charac- 
ters suited to the various districts in 
which at one time they originated. 

From a commercial point of 
view, the weisjht of a barley is of 
importance and good qualities give 
a weight of 40 grms. per 1000 corns, 
or 62 to 67 kilos per hectolitre for thin 
barleys and as much as 70 kilos per 
hectolitre for the larger ones. The 
grains should have a floury and not 
a vitreous appearance when cut 
through, and there should be few 
broken corns as these do not ger- 
minate and become mouldy on the 
malting floor. Germination tests, 
made on 500 or 1000 corns, should 
show at least 95 per cent, of ger- 
m nated corns in 5 to 6 days. With barley harvested under wet conditions, the ends of the corns are darkened. 

The world's production of barley in 1906 amounted to 315,000,000 quintals ; in France, in 1909, 10,800,000 
quintals (or 17 million hectols.) were grown on an area of 737,300 hectares ; Italy imported 104,000 quintals 
in 1907, 124,000 in 1908, 176,000 (value 126,120) in 1909, and 178,000 (value 128,120), mostly from Austria- 
Hungary, in 1910. 

1 The best hops are cultivated in Bohemia (at Saaz), Bavaria, Posen, Wiirtemberg, Baden, and Alsace- 
Lorraine, where they are picked towards the end of August. If they are too ripe the bracts of the hop-cones 
open and lupulin is lost. 

The hop should have a yellowish green, and not a brown, colour, and the bracts should not be opened ; a 
too green colour indicates that the hops have been picked in an unripe condition. The seeds have no value for 
brewing purposes, but the largest hops are of least value. They should not have an unpleasant odour. Since 
the fresh hops contain 75 to 85 per cent, of moisture, so that they will not keep, it is necessary to dry them in the 
air or in ovens at 25 to 30 with a strong current of dry air, until they contain only 12 to 15 per cent, of moisture; 
they will then keep well, even for a year or more. Their keeping qualities may be improved by sulphuring them 
(with S0 2 ) either when dry or during the drying. Sulphuring is, however, often applied to inferior hops to mask 
their defects. 

The better qualities are seldom sulphured and, when they are well dried, are kept tightly compressed in 
large sacks or in evacuated metal cylinders. They may also be kept in a very cool place (cold store). 

The bitter flavour and keeping properties imparted by hops depend on their content of a- and p-bitter acids, 
which varies from 6 to 18 per cent, and is determined by Lintner's method as follows : 10 grms. of an average 
sample of the hops are heated in a flask graduated at 505 c.c., with 350 c.c. of light petroleum (b.pt. 30 to 50) 
for six hours on a water-bath at 40 to 45, an efficient reflux condenser being fitted to the flask. When the latter 
Is cold, it is filled to the mark with light petroleum and shaken, the contents then being filtered. 100 c.c. of the 
filtrate, mixed with 80 c,c. of alcohol, we titrated with a drcinormal potassium hydroxide solution in 




Fia. 152. 



STEEPING 



163 



3. WATER. Formerly water for brewing purposes was invested with a mysterious 
importance, but nowadays the water is tested in a much more rational and rigorous 
manner. Preference used to be given to moderately soft water, but now waters of medium 
hardness are regarded as best, as it is found that a certain quantity of calcium sulphate 
aids fermentation ; but if the water is too hard, less extract is obtained from the malt 
and hops. Iron is also harmful, and especially so are waters contaminated with bacteria. 1 

The principal operations in the manufacture of beer are as follow : 

(1) CLEANING OF THE BARLEY, to remove dust, soil, stones, damaged and light 
corns, &c. by means of sieves, fans, &c. 

(2) STEEPING OF THE BARLEY for 2 or 
3 days in water at 11 to 12 in order that it may 
absorb the water necessary for germination. 

For this purpose use is generally made of the 
Neubecker tank (Fig. 153) made of iron plates, 
opan at the top and cone-shaped at the bottom. 
In the middle is a wide perforated pipe, E, which 
is surrounded by the barley (500 to 3000 kilos). 
The water is supplied by the pipe W, and is 
discharged through the perforations of E, thus 
covering the barley ; it is then discharged from 
the top of the tank through the pipe U, the 
lighter floating corns being carried away. After 7 
or 8 hours the water is run off through the tap 
C, and the moist barley left exposed to the air for 
5 or 6 hours. Fresh water is then introduced and 
left for 10 to 12 hours, after which it is run off 
and the grain exposed for 5 or 6 hours, and so 
on. This procedure is continued for 30 to 50 hours in summer or 70 to 100 hours 
in winter, the corns having in that time absorbed about 40 per cent, of water. 
Steeping of the barley in lime-water has been suggested as a means of preventing 
abnormal fermentations (Windisch, 1901). In some cases steeping is preceded by 
washing the barley in running water in rotating cylinders ; or else compressed air is 
forced into the steeping vessels at frequent intervals, so as to stir the barley. The 

of 10-15 drops of phenolphthalein solution. If much fat is present an aliquot part of the light petroleum solution 
is evaporated and the residue extracted with methyl alcohol, which does not dissolve the fat and, on evaporation, 
gives the bitter acids ; these can then be weighed. 

The quality and commercial value of hops are influenced largely by the nature of the soil and the quality 
of the manure used, as well as by the variety of the hop itself. 

Chemical composition does not always give satisfactory indications for judging of the value of hops, and this 
is almost always done by men experienced in valuing hops. Hops give up to alcohol 22 to 30 per cent, of extract, 
about two-thirds of which is composed of a resin giving the bitter flavour and acting as an antiseptic towards 
certain bacteria injuriously affecting the keeping of the beer, although it has no influence on the yeast. The 
flavour of the beer is also considerably affected by the tannin contained in the hop to the extent of 2 to 4 per cent. 

The determination of the ethereal extract is also employed in judging of the quality of hops ; with good 
qualities, after evaporation of the ether, 27 to 28 per cent, of residue is left (see above, Lintner Test). 

The total area of the earth's surface under hops in 1909 was 97,421 hectares (of which 29,000 hectares in 
Germany) and the production varied from 10 to 15 quintals per hectare. Germany imported 28,000 quintals of 
hops in 1908 and 36,360 in 1909, but exported 124,000 quintals in 1908 and 88,000 in 1909. The hops imported 
by the United States were valued at 247,200 in 1910 and at 427,400 in 1911, and those exported at 461,400 
in 1910 and at 851,600 in 1911. 

1 The compositions of various waters are as follows : 




FIG. 153. 





Good 


Medium 


Cad 


Dry residue ...... 


250-450 


450-550 


550-700 A 


Ferric oxide and alumina (Fe 2 O a ,Al 2 O 3 ) 


0-1-5 


1-5-2-5 


3 1 .- 


Lime (CaO) 


120-150 


150-200 


200-300 1 .2 


Magnesia (MgO) ..... 


20-50 


50-80 


80-120 1 3 


Sulphuric acid (SO,) 


20-60 


60-80 


100-200 j 


Ammonia ....... 








trace-1-5 / <> 

1 Q< 


Nitrates ....... 





0-0-5 


0-5-1-5 j 


Organic matter (as oxygen absorbed) . 


0-4-1-5 


1-5-2-0 


2-3 | 


Hardness (French degrees) .... 


15-25 


25-35 


35-50 / PH 


Number of bacteria per 1 c.c. 


50-500 


500-4000 


4000-10,000 



These numbers are only indicative apd mupt not be tefcen too strictly, 



164 



ORGANIC CHEMISTRY 



steep-water becomes yellowish brown and acid, and after some time undergoes lactic 
and butyric fermentations. At the end of the operation, the barley is discharged through 
the lower aperture, A, by undoing the screw, B, and raising the tube, E, by means of 
the lever, D. 

(3) GERMINATION OF THE BARLEY. The steeped barley is carried to the 
spacious malting floor, which is fitted with numerous windows to allow of the renewal 

of the air when desired, and is arranged so that 
the temperature can be maintained constant at 
15 to 20. On the impermeable floor (of cement 
or asphalte), the barley is spread out in a layer 
50 to 60 cm. deep, and on the second day the 
mass is moved with wooden shovels so as to 
reduce the depth to 30 to 35 cm., this being 
further reduced to 15 cm. on the third day. 
Every 8 Or 10 hours the grain is turned, 
the floor being kept well ventilated. The 
temperature gradually rises, but should - not be allowed to exceed 20 ; if necessary 
it can be modified by turning more often and thinning out the barley. After the second 
day the radicles begin to sprout and later the plumule. In eight to ten days the rootlets 
become twice or three times as long as the corn and the transformation of nitrogenous 
material into diastase is at its maximum (Fig. 154 shows the various stages in the ger- 
mination of barley). The germination should then be interrupted so as not to lose any 
part of the diastase formed, the green malt then containing about 40 per cent, of moisture. 
A floor of 20 sq. metres is sufficient for only 1000 litres of steeped grain. If the piece 
dries too much, it is moistened by sprinkling with water. In order to prevent mould- 
growth when the floor is free, it, and also the walls, are washed with 1 per cent, calcium 
bisulphite solution, the floors being then well dried by ventilation. 




FIG. 154. 



- v ; ;:.,..,-. '' -. ?>>'-... -K^': .o>v,' ' v . ; ^- x ;.- -..-.> ^u.^.:..^^^""- ';v.\ ,;- ,;<V ; ?^-'"\ 




FIG. 155. 



FIG. 156. 



The germination is now sometimes carried out on the pneumatic system, use being 
made of the Galland apparatus (Figs. 155 and 156), which consists of a double sheet-iron 
drum, T, rotated by means of the wheels 6 (one rotatiqn in forty minutes). The inner 
drum is perforated and is filled to the extent of four-fifths with barley from the steeping 
tank, W ; along the axis of the cylinder passes a pipe which is also perforated. Air 
sucked in by a fan, Z, is moistened in A by means of pulverised water, and from L passes 
into the jacket of the drum, then through the perforations and the grain to the central 
pipe, m . Thence it proceeds to 8, and so through the fan Z to the shaft ; a thermometer 
here^shows the temperature of the air, and if this becomes too high the speed of the fan 



PNEUMATIC MALTING 



165 



is increased. If 100 kilos of barley are taken and the air enters at 12 and issues at 20, 
4500 cu. metres of air are required per hour ; if the air is to leave at 16, 10,000 cu. metres 
per hour are necessary. The germination lasts 8 to 9 days. 

To stop the germination, a current of dry air, heated to 22 to 25 or mixed with gas 
rich in C0 2 (to diminish 
the supply of oxygen), 
is supplied ; in a short 
time the moisture content 
of the grain is reduced 
from 40 per cent, to 20 to 
25 per cent. 

For a malting to'give 
continuously 2000 to 
5000 kilos per day, three 
to four steeping- tanks are 
used, these feeding six 
to eight Galland drums 
arranged in batteries (Fig. 
157) ; 6 to 10 horse -power 
are required for turning 
the drums, driving the 
fans, &c. FIG - 157 ' 

The water necessary for steeping amounts to about 10 to 12 times the weight of the 
barley, rather less being required to moisten the air for pneumatic malting. The steep-water 
can hence be used again for the latter purpose if at any time the water-supply is scarce. 





FIG. 158. 

Another system of malting, used especially in France, is that of Saladin (shown in 
perspective in Fig. 158, while Fig. 159 shows a longitudinal section of one of the vessels 
and Fig. 160 a transverse section of the vessels). There is one vessel, made of concrete 



1 




M 


p 






if 




<a rri >A 


G=r^ 


""tSS? L "^l 


i 


"Q "D~ D ~D"D B "Q n T D D"C" B "n o ~G~D a a Ta o"o~ B"o 


t 


I 






C L 




D 





i 




FIG. 159. 



FIG. 160j 



and fitted with a perforated false bottom of sheet-iron, for each day that the germination 
lasts. These vessels, B, communicate under the false bottom with a channel containing 
a fan which draws moistened'air through the mass of barlej' in the vessel (50 cm. deep). 



166 



ORGANIC CHEMISTRY 



Above each vessel is a mechanical turner, A, with a number of screws which rotate in the 
barley as the turner passes along the vessel. The turner can be transported from one 
vessel to another and is put into operation twice a day at first (the temperature of the 
barley being 12 to 14), then four times a day (at 15 to 18), and finally twice a day (at 
18 to 50"). In some maltings a saving is effected by operating the fan only at intervals 
when the temperature rises. Dry air, drawn along the channels, S, is finally passed 
through the malt. 

The advantages of the various mechanical processes over the old system of malting 
are that they can be worked continuously and at any season of the year, while they occupy 
less space, allow of efficient regulation, of temperature, economise labour and general 
exp3nses and diminish the percentage of waste. 

(4) KILNING OF MALT. The germinated barley is too moist to keep sound, and 
as breweries require large stocks of malt this must be dry and capable of being kept. If 

the moisture is reduced to 6 per cent, by air alone the 
germination process is stopped, and on subsequently 
raising the temperature to 60 a slight diastatic saccharin- 
cation occurs, this being greater in amount if the moisture 
is kept at 12 to 15 per cent. ; beyond 70 the diastase is 
destroyed and certain substances formed which give good 
flavour, aroma and fullness of taste to the beer and at the 
same time furnish food for the yeast. When the tempera- 
ture exceeds 100 part of the maltose is caramelised for 
the making of dark beers and a considerable amount of 
nitrogenous substances, which would cause the beer to keep 
badly, thrown out of solution. 

In order not to destroy too much of the diastase and to 
make malt suitable for pale beers the drying must first be 
conducted with warm air. When the proportion of mois- 
ture has reached 5 to 6 per cent, the diastase can withstand a 
temperature of 60 to 70 without losing much of its activity ; 
whilst if the malt is heated when it contains too much 
moisture (15 to 20 per cent.) the diastase is rapidly destroyed. 
The drying is carried out in a current of warm air (or of air 
mixed with the hot gases from a coke or anthracite fire), 
which passes through the green malt placed in layers 1 5 to 20 
cm. deep on wire or tile floors, often arranged one above 
the other. Above the upper floor is a chimney, which 
increases and facilitates the draught started by suitable 

fans. The air is heated by passing directly over a fire or through batteries of tubes 
heated in the usual way. During the drying the malt is turned by a suitable mechanical 
device, at first every 2 hours and later on continuously. The temperature of the air 
gradually rises, during the course of 84 to 90 hours, by 30 to 35 (during the first few 
hours germination still proceeds feebly, causing increase in the diastase), and ends at 100 
to 110 (for dark beers). Drying is usually effected in less than 48 hours, and it is only 
beyond 80 that the diastase partially loses its saccharifying properties (at 90 it loses 
50 per cent, and at 100 85 per cent.) ; this loss is, however, an advantage, since a too 
highly diastatic malt leads to excessive saccharification and hence to increased attenua- 
tion in the subsequent fermentation, so that the beer tastes less full. The peptases 
also are destroyed beyond 90, so that the nitrogenous substances are dissolved to a less 
extent and the beer hence keeps better. 

Fig. 161 shows diagrammatically a section of a two -floor malt -kiln in which the air is 
heated in the tubing, t, surrounding the ducts carrying the hot fumes from the coal burning 
on the grate, F. The hot air then traverses the malt on the floors, B and C, and issues 
from the chimney, D, the turning apparatus, a, being kept in motion meanwhile. To obtain 
100 kilos of dry malt in 24 hours (maximum temperature 90 to 100) 20 kilos of coal are 
required. For making dark beers of the Munich type part of the kilned malt is further 
roasted at about 200 in suitable rotating iron cylinders heated by direct fire ; this treat- 
ment leads to the formation of caramel, which colours the beer, the malt being then called 
coloured malt. The temperatures on the malting floors and kiln are registered by auto- 




FIG. 161. 



MALT ANALYSIS 167 

matic devices which construct diagrams showing the temperature at any particular 
moment. 

Nowadays malt for pale beers is sometimes heated only to 25 to 30. 

The kilned malt leaves the kiln with 2 to 5 per cent, of moisture and is then cooled and 
stored in silos or large bins. A malt kept for only 1 or 2 months is to be preferred to an 
older one. 1 

1 The commercial value of a malt is determined largely by its yield of extract, which is measured as follows : 
45 grins, of ground malt are placed in a tared flask with 200 c.c. of water, the temperature being kept at exactly 
45 for half an hour and then raised 1 per minute up to 70, this temperature being maintained until the liquid 
no longer gives a blue colour with iodine ; the time required at 70 to reach this point is noted (saccharification 
test). The mass is then cooled and water added to bring its total weight up to 450 grins. ; after mixing and 
filtering through a dry filter, the density of the liquid is determined at 15 and by Windisch's or Schulze's tables 
the corresponding quantity of extract deduced. The latter can also be obtained from Balling's tables (see below). 
note being taken that they yield low values, the deficit being 0-08 grm. per cent, for specific gravities up to 1-01 ; 
0-345 for specific gravities up to 1-05 ; 0-48 for specific gravities up to 1-06 ; and 0-4 for specific gravities up to 
. 1-08. If the maltose is to be determined directly, 10 grms. of the filtered saccharine liquid (corresponding witli 
1 grm. malt) are diluted to 100 c.c., various quantities of this liquid being then titrated with Fehling's solution, 
1 c.c. of which corresponds with 0-0075 grm. of maltose. 

C. Lintner (1886-1908) has modified the Kjeldahl method for determining the diastatic power of malt as follows : 
25 grms. of the ground malt are extracted for 6 hours with 500 c.c. of water at the ordinary temperature, the 
mixture then being filtered ; 2 c.c. (for pale malts) or 8 c.c. (for dark malts) of the filtrate are added to 100 c.c. 
of 2 per cent, soluble starch solution and the mixture left for exactly half an hour, at the end of which time 10 c.c. 
of caustic soda solution are added. Into a number of test-tubes, each containing 5 c.c. of Fehling's solution, 
are introduced varying quantities of the saccharified starch solution (e.g. from 1 to 6 c.c.) ; the tubes are next 
immersed for ten minutes in a boiling water-bath and then taken out, and the precipitated cuprous oxide allowed 
to settle ; it can then be seen in which of the tubes the Fehling's solution is just completely reduced and in which 
it is just not reduced. A more exact result can be obtained by using quantities of the saccharified starch solution 
intermediate to those corresponding with these two tubes. When 0-1 c.c. of the cold water malt extract, acting 
for one hour on 10 c.c. of 2 per cent, soluble starch solution, forms just sufficient maltose to reduce 5 c.c. of 
Fehling's solution, the malt is said to have the diastatic power 100 ; if 0-2 c.c. of the malt extract is required, 
the diastatic power is taken as 50, and so on. 

BALLING'S TABLE 





Degrees 




Degrees 




Degrees 




Degrees 




Balling or 




Balling or 




Balling or 




Balling or 


Sp. gr. 


grms. of 


Sp. gr. 


grms. of 


Sp. gr. 


grms. of 


Sp. gr. 


grms. of 


at 17-5 


saccharose 


at 17-5 


saccharose 


at 17-5 


saccharose 


at 17-5 


saccharose 




per 100 




per 100 




per 100 




per 100 




grms. liquid 




grms. liquid 




grms. liquid 




grms. liquid 


1-0010 


0-250 


1-0210 


5-250 


1-0410 


10-142 


1-0610 


14-904 


1-0020 


0-500 


1-0220 


5-500 


1-0420 


10-381 


1-0620 


15-139 


1-0030 


0;750 


1-0230 


5-575 


1-0430 


10-G19 


1-0630 


15-371 


1-0040 


1-000 


1-0240 


6-000 


1-0440 


10-857 


1-0640 


15-604 


1-0050 


1-250 


1-0250 


6-244 


1-0450 


11-095 


1-0650 


15-837 


1-0060 


1-500 


1-0260 


6-488 


1-0460 


11-388 


1-0660 


16-070 


1-0070 


1-750 


1-0270 


6-731 


1-0470 


11-571 


1-0670 


16-302 


1-0080 


2-000 


1-0280 


6-975 


1-0480 


11-809 


1-0680 


16-534 


1-0090 


2-250 


1-0290 


7-219 


1-0490 


12-047 


1-0690 


16-767 


1-0100 


2-500 


1-0300 


7-463 


1-0500 


12-285 


1-0700 


17-000 


1-0110 


2-750 


1-0310 


7-706 


1-0510 


12-523 


1-0710 


17-227 


1-0120 


3-000 


1-0320 


7-950 


1-0520 


12-761 


1-0720 


17-454 


1-0130 


3-250 


1-0330 


8-195 


1-0530 


13-000 


1-0730 


17-681 


1-0140 


3-500 


1-0340 


8-438 


1-0540 


13-238 


1-0740 


17-909 


1-0150 


3-750 


1-0350 


8-681 


1-0550 


13-476 


1-0750 


18-136 


1-0160 


4-000 


1-0360 


8-925 


1-0560 


13-714 


1-0760 


18-363 


1-0170 


4-250 


1-0370 


9-170 


1-0570 


13-952 


1-0770 


18-590 


1-0180 


4-500 


1-0380 


9-413 


1-0580 


14-190 


1-0780 


18-818 


1-0190 


4-750 


1-0390 


9-657 


1-0590 


14-428 


1-0790 


19-045 


1-0200 


5-000 


1-0400 


9-901 


1-0600 


14-666 


1-0800 


19-272 



Correction of Degrees Balling for Various Temperatures 



Determina- 
tion made 
at tempera- 
ture of 


Correction 
of degrees 
Balling 


Determina- 
tion made 
at tempera- 
ture of 


Correction 
of degrees 
Balling 


Determina- 
tion made 
at tempera- 
ture of 


Correction 
of degrees 
Balling 


Determina- 
tion made 
at tempera- 
ture of 


Correction 
of degrees 
Balling 


Deg. 




Deg. 




Deg. 




Deg. 




4 


-0-43 


11 


-0-22 


17-5 





24 


+ 0-27 


5 


- 0-40 


12 


- 0-19 


18 


+ 0-02 


25 


+ 0-32 


6 


- 0-37 


13 


- 0-16 


19 


+ 0-05 


26 


+ 0-37 


7 


- 0-34 


14 


0-13 


20 


+ 0-09 


27 


+ 0-42 


8 


- 0-31 


15 


-0-10 


21 


+ 0-13 


28 


+ 0-48 


9 


-0-28 


16 


-0-06 


22 


+ 0-17 


29 


+ 0-54 


10 


-0-25 


17 


0-02 


23 


+ 0-22 


30 


+ 0-60 



168 



ORGANIC CHEMISTRY 




Malt kilned with fumes direct from a coal fire communicates to the beer a certain 
flavour from the smoke. Also, when coal is employed which contains arsenic, the latter 
becomes deposited on the malt and hence finds its way into the beer. Arsenic may also 
be present in the glucose often used in brewing ; in this case it is introduced by the 
employment of arsenical sulphuric acid in the manufacture of the glucose from starch. 

(5) CLEANING AND GRINDING. 
Before the malt is mashed it is freed 
from dust and rootlets by means of 
rotating drums of metal gauze (a kind 
of sieve) furnished with fans. It is 
then ground but not too finely, the 
husks being kept whole as far as pos- 
sible, since they serve in the subsequent 
operations as filtering material ; if the 
malt is ground too fine it cannot be 
exhausted, as the liquid will not drain 
off. A suitable form of mill is the 
Excelsior Mill, made by Messrs. 
Krupp (Figs. 162 and 163). The shaft, 
g, fitted with fast and loose pulleys, 
s and t, can be shifted from right to 
left or vice versa through the stuffing- 
boxes, m, by means of the lever, d. One 
toothed disc, a, is fixed, whilst the 
FIG. 162. other, 6, rotates with the axis, g, and 

is so adjusted that the teeth pass 

through the tooth spaces of the other disc. The barley from the hopper, /, falls between 
the two discs, where it is ground, the ground malt (grist) being discharged at n. For the 
sake of economy the discs are toothed on both faces, so that when one face is worn the 
other can be used. 

The total loss in weight suffered by the barley during steeping, germination, kilning, 
cleaning, and grinding amounts to about 20 per cent. 

(6) MASHING. This consists in subjecting the ground malt to the action of warm 
water so that the diastase may act on 
the starch and convert it into soluble 
products. The temperature at which the 
maximum extract is obtained is about 65, 
whilst at 55 the starch is only very 
slightly attacked by diastase, and above 
70 diastase loses its saccharifying pro- 
perties very largely and the wort filters 
through the grains (husks ; see later) with 
difficulty this effect is aggravated by 
coagulation of part of the proteins. The 
quantity and quality of the water have 
an influence on the mashing, the presence 
of calcium sulphate facilitating the forma- 
tion of maltose and maltodextrins and 
increasing the amount of nitrogenous substances dissolved. 
3 hectols. of beer are made. 

There are two systems of mashing : the infusion method (at 65 to 72), used only in 
top-fermentation breweries, and the decoction system, used for bottom-fermentation and 
sometimes for top-fermentation beers, and with highly diastatic malt or when unmalted 
barley is used with the malt. 

(I) The infusion process, used largely in England and Scotland, less in France and 
still less in Germany, is usually carried out in one of two ways : (i) rising infusion, where 
the malt is first mixed to a paste with 10 per cent, of cold water and then with hot water 
in the ratio of two parts of water to one part of malt, so that a temperature of 40 is 
attained. To raise the temperature of 1 kilo of malt (which has a specific heat of about 




FIG. 163. 
From 1 quintal of malt 2 to 



MASHING 



169 



0-5) from 20 to 40 requires 10 Calories, which can be supplied by 2 litres of water at 
45, the latter falling to 40 on losing 10 Calories ; owing, however, to unavoidable loss 
of heat, water at 48 to 50 should be used. 

This mixing is done in a circular mash-tun of metal or wood, furnished with a 
perforated false bottom several centimetres above the true bottom, in which are fitted 
the pipes supplying the hot water (Fig. 164). The mashing and subsequent mixing are 
effected by efficient mechanical stirrers or rakes. 

As soon as the mash has reached the temperature of 40 water at 80 is gradually 
introduced, the temperature being raised to 63 to 65 in half an hour. It is next mixed 
for 60 to 70 minutes, the liquid being then discharged by^opening the taps under the false 
bottom so that the liquid passes through the grains and is conducted to the copper. The 
residue in the tun is mixed for 15 minutes with water at 75, the liquid being run off and 
the grains finally washed with water at 80, all these extracts passing to the copper. In 
this way almost complete saccharification is attained and the subsequent fermentation 
produces considerable attenuation. If 
a less attenuation is desired, either 
a higher temperature (72 to 73) is used 
in place of 65, or high-dried malt is 
used. 

(ii) Descending infusion, which is 
rarely used, consists in bringing the 
mass directly to a temperature of 65 to 
70 with very hot water and then allowing 
it to fall slowly to 35 to 40. 

Neither of these methods admits of 
the use of rice or maize, the starch of 
which is attacked by diastase only after 
it has been heated with water to 80 to 
85. Hence with such material the 
decoction process is used. 

(II) Decoction Process. This is 
largely used in North Germany, Austria, 
and Belgium, and allows of the use of F IG . 164. 

unmalted barley, rice, maize, wheat, &c. 

The malt grist is first mixed to a paste with cold water so as to dissolve the diastase, 
this being carried out in a metal vessel without a false bottom ; by the addition of small 
quantities of boiling water the temperature of the mass is raised gradually to 35, From 
one-third to one-half of the turbid wort (Dickmaische) is transferred to a double-bottomed 
copper heated with steam. In many cases coppers with direct-fire heat are used, these 
being furnished with chains which scrape on the bottom and so prevent caramelisation of 
the mass which settles (Fig. 165 shows a complete decoction or infusion plant). The 
wort transferred to the copper is boiled for 20 to 40 minutes and is then returned to the 
original tun, where it raises the temperature to about 55. Another one-third or one-half 
is similarly removed, boiled, and returned, the temperature being thus raised to 65 ; the 
saccharification has then reached a maximum and the mash become thinner. The 
complete disappearance of starch is controlled by the reaction with iodine. About 
one-half of the wort is again removed, boiled, and returned, the temperature being thus 
raised to 75. During all these operations continual stirring is maintained. The greater 
the number of decoctions made the greater will be the density of the wort and the darker 
the beer. The turbid wort is either allowed to deposit in tuns with false bottoms as 
shown in Fig. 164, or passed through filter-presses (see Sugar Industry) to clarify it, the 
grains remaining in the form of cakes being well washed. 1 

When considerable quantities of other cereals are to be used with the malt use 

1 The grains are composed of the whole of the husks of the ' malt coagulated proteins, pentosans, fat, 
maltose and dextrin. They serve as excellent cattle-food, but if not consumed in the course of 24 hours, they 
undergo change ; they may, however, be placed in silos and dried in a suitable apparatus (see Tig. 149, p. 154). 
Wet grains contain 70 to 80 per cent, of water, 4 to 6 per cent, of protein, 1 to 3 per cent, of fat, 8 to 14 per cent, 
of extractive substances, 1 to 3 per cent, of ash, and 3 to 9 per cent, of cellulose. Dried grains contain 6 to 
18 per cent, of water, 17 to 26 per cent, of protein, 4 to 9 per cent, of fat, 35 to 55 per cent, of extractive 
substances, 3 to 12 per cent, of ash, and 9 to 20 per cent, of cellulose ; they have a brown colour, a pleasing 
odour of new bread and a sweet taste ; they make a good food to follow wheat or oat bran. 




170 



ORGANIC CHEMISTRY 



is made of a Henze pressure apparatus, as described under Distilling (Fig. 104, 
p. 119). 

The wort thus obtained is boiled with a certain quantity of hops until a certain amount 
of concentration has been effected. This boiling finally destroys the diastase, intensifies 
the colour of the wort and aerates it, and oxidises various substances producing acid 
bodies ; it completely sterilises the liquid, which is also clarified owing to the precipitation 
of nitrogenous substances, partly by the tannin of the hops. 

The decoction of the hops is carried out in a separate vessel, the boiling liquid being 
continually circulated until the hops are exhausted. The decoction is then added to the 
boiling wort, principally towards the end of the operation ; if added earlier the hop 
extract loses some of its aroma. The direct addition of the hops to the copper is still 
used, although the method is not a very rational one ; it is better to pass the boiling 
wort from time to time into a separate vessel containing the hops and then back to the 
copper, this procedure being repeated until the hops are exhausted. 




FIG. 165. 

In general, 400 to 500 grms. of hops are used per hectolitre of beer, or 2-5 to 5 kilos for 
every quintal of malt mashed. More hops are usually employed for beers to be kept for 
some time (lager beer, stock ale) than for draught beer. The lupulin powder contained in 
the hop gives up resins and essential oils, while the leaves give tannin and the stalks 
somewhat bitter substances ; the whole gives the bitter taste and aroma of the beer, and 
causes the latter to keep better. A temperature of 75 (Pasteur) is sufficient to sterilise 
a hopped beer, since the resins have a marked antiseptic action. 

The boiling of the wort is carried out in copper vessels (see Fig. 165, a) heated by direct 
fire or by indirect steam (passed through coils or through the double bottom of the copper), 
the boiling being continued for 4 to 6 hours with dilute worts (infusion) and only 1^ to 2 hours 
with the more concentrated decoction worts ; as a rule boiling is continued until the 
density reaches a certain value for the particular kind of beer to be made (see later). The 
temperature during boiling should be gradually raised and registered. In many modern 
breweries there are automatic registering thermometers which show the whole course of 
these operations. When the boiling is finished the wort is allowed to stand for a time, 
and the Inland Revenue officials then generally make their first measurements (they 
calculate that 1 kilo of dry malt should give 25 litres of wort with a density of 1 Balling, 
5 litres at 5, &c., an allowance being made of 10 per cent.). The copper is then dis- 
charged, the hops being strained off, and the wort pumped to the cooler, which is usually 
at the top of the building. These coolers are large shallow vessels of iron (or copper or 
wood) in whicfy the coagulated proteins are deposited ; the temperature here is not allowed 



COOLING OF WORT 



171 



to fall below 60 to 65, otherwise contamination with harmful organisms (butyric, lactic, 
&c.) might occur. In Italy the tax on the manufacture of beer is calculated from the 
volume, temperature, and specific gravity of the wort in the cooler (see later). The wort 
is next cooled rapidly by suitable refrigerators to 2 to 3 (for bottom fermentation) or 
12 to 15 (for top fermentation). One form of refrigerator which is much used consists of 
a number of superposed, communicating horizontal tubes (Fig. 166). In the tubes of 
the upper half water circulates, and in those of the second half brine at a temperature 
of -6 or -8 from a refrigerating machine (see vol. i, p. 231). The wort flows down in 
a thin skin over the outside of the tubes, meanwhile dissolving an appreciable quantity 
of air. The cooled and aerated wort flows down to the fermenting vessels placed in cool 
rooms ; for bottom fermentation these are cooled to about by pipes conveying cold 
brine. The wort from the coolers is turbid and should be filtered through conical cloth 
bags or filter -presses. In some modern breweries the coolers are omitted in order to 
avoid any possible contamination (which is, however, difficult with hopped wort at 60) 
and the wort is passed direct from the copper to the closed refrigerator and the filter- 
press, aeration being afterwards effected with air filtered through cotton -wool. 

The refrigerators consume considerable 
quantities of water, and where this is 
scarce the warm water from the refrigera- 
tors is cooled by means of pulverisers 
or by causing it to flow down over 
twigs, the evaporation thus caused often 
lowering the temperature below that of 
the air (see section on Sugar). The boil- 
ing of the wort has hence effected a con- 
centration, the preparation of a sterile 
(aseptic) liquid, and the extraction of the 
useful principle of the hop, the tannin of 
which has partially precipitated the pro- 
teins. If pale beer is to be brewed the 
wort can, if necessary, be clarified during 
the boiling by the addition of a little 
tannin. During the cooling on the cooleis 
the wort takes up the oxygen necessary 
for the oxidation of the resins, for clarify- p IG ^gg 

ing it and, more especially, for aiding the 
development and multiplication of the yeast during the initial stages of the fermentation 

Contact of the wort with tin, e.g. tinned vessels, is avoided, as turbidity of the beer 
may be caused thereby, especially if the wort is acid or rich in carbon dioxide. 

FERMENTATION. From the density (degrees Balling) or the dry 
extract of the wort, the extract yielded by the materials may be deduced, and, 
under favourable conditions, the dry extract amounts to about 70 per cent, 
of the weight of the malt, whilst with bad working it may be as low as 45 per 
cent. When ready for fermentation the wort contains mainly maltose, malto- 
dextrins, dextrins, a little saccharose, glucose, and levulose, besides nitro- 
genous substances partially peptonised and transformed into amino-acids ; 
also lactic acid and potassium phosphates. Fermentation with yeast converts 
the carbohydrates more or less completely into alcohol and carbon dioxide. 1 

1 In addition to what has been said on pp. Ill and 123 on ferments and yeasts in general, the following i& 
of interest, especially to the brewing industry : 

All yeasts which attack only saccharose, maltose, glucose, and levulose, giving alcohol and carbon dioxide, 
are feebly attenuating yeasts of the so-called Saaz type (e.g. the beer-yeasts of Li6ge, which yield fairly full-tasting 
sweet beers containing little alcohol). Other yeasts are also capable of fermenting the combined maltose of 
maltodextrins by means of a special enzyme studied by Delbriick, maltodextrinase ; these yeasts give the maximum 
attenuation and form the so-called Frohberg type, producing alcoholic, highly attenuated beers even from weak 
worts. Between these types Saaz and Frohberg there exist intermediate ones giving in 4 days at 25 to 27, 
well-defined attenuations in a normal wort. 

Certain other yeasts are capable of fermenting dextrin combined as maltodextrins, since they contain an 
enzyme which Delbriick has termed dextrinase. Such is the Schizosaceharomycet Pombi : , separated from the 
millet beer of the Egyptians. These yeasts constitute the so-called Logos type. Wild yeasts are all strongly 
attenuating and may produce turbidity in finished, slightly fermented beers, which they referment. The yeasts 




172 ORGANIC CHEMISTRY 

The concentration of the wort most favourable to the multiplication of 
yeast is 15 Balling (corresponding with a specific gravity of 1-06). 1 A too 
dilute wort or one prepared with an excessive proportion of non-germinated 
grain has not sufficient assimilable nitrogenous food (amino-acids), and this 
is remedied^ by the addition of zymogen, which is a commercial product. 
During the period when the yeast develops (first stage of the fermentation) 
little alcohol and much carbon dioxide are produced. 

Two distinct methods of fermentation are in use : top fermentation, used 
generally in England, Belgium, and Holland, and largely in France, and also, 
at one time, exclusively in Italy ; and bottom fermentation, usually employed 
in Germany, Austria, and Denmark, and in general use in countries where 
beers of the Munich and Pilsen types are made. In hot countries it is easier 
to regulate bottom fermentation (by refrigeration) than top fermentation, 
since in summer the temperature of the air is often high enough to have an 
injurious effect on top fermentation. So that, as a refrigerating plant is 
necessary, the bottom fermentation system is preferable. 

The difference between bottom and top yeasts is that the latter are covered 
with viscous, mucilaginous substances and readily stick together and carry 
bubbles of carbon dioxide developed in the wort to the surface and so produce 
a rapid feimentation ; the former, however, fall to the bottom of the fer- 
menting vessel and, even under the microscope, are not found in large masses. 
Top yeasts develop well only at temperatures above 12 best at about 
24 and effect complete fermentation in 4 to 6 days, whilst the bottom 
yeasts develop below 10 and, after the vigorous primary fermentation of 
8 to 12 days at 6 to 8, continue the maturation of the beer for two or 
three months by a secondary fermentation at a low temperature (0 to 2) ; 
this procedure gives beers of less attenuation which can be produced or con- 
sumed even in summer (lager beer). Top -fermentation beers are almost 
always more highly attenuated, are consumed at once (draught beer), and are 
made more especially in the cold weather ; they can, however, be kept, and 
in some cases stock beers are made on this system. 

The advantages and disadvantages of the two processes are as follow : 

Top fermentation does not require costly refrigerating plant, and hence lends itself 
to the construction of small breweries ; further, the beer can be sold immediately, and 
the capital, although small, thus frequently renewed each year. The control and successful 
working of top fermentation are, however, more difficult owing to ready contamination 
with numerous harmful bacteria which find at 15 to 20 the most favourable conditions for 
their development, especially in the summer ; in bottom-fermentation beers only yeasts 
can develop at to 2. 

With top fermentation, in which at first yeasts of the Saaz type and those intermediate 
to the Saaz and Frohberg types predominate, there develop later bacteria and also 
Frohberg yeasts (especially during the secondary fermentation), and both of these render 
difficult the preparation of a clear beer which does not become turbid after fermentation ; 
on the other hand, a bright beer is easily and naturally obtained by bottom fermentation. 
In summer, then, unless an abundant supply of cold water and also cool cellars are avail- 
intermediate to the Saaz and Frohberg types and also Frohberg yeasts themselves are especially active in the 
secondary fermentation ; they increase the apparent fullness of the beer, even when this is light, arid maintain 
a continuous and desirable evolution of carbon dioxide by slowly fermenting the maltodextrius and even dextrins. 
In order to grow and multiply, yeasts generally require, in addition to carbohydrates and free oxygen, nitro- 
genous substances, but they cannot make use of nitrates, or ammonium salts, or even the true proteins ; they 
can, however, utilise the decomposition products of the latter, namely, the amino-acids (such as asparagine) pro- 
duced by the proteolytic enzymes secreted by healthy yeasts. They-.require also mineral substances, e.g. calcium 
and potassium phosphates. 

The oxygen of the air is, as has been said, indispensable to the development and multiplication of yeast, and 
well-aerated worts facilitate the multiplication during the first few days, when only CO. and H,O are produced 
when, however, the supply of free oxygen diminishes or ceases, the yeast produces more especially alcohol and 
carbon dioxide. There are also saccharomyces which are solely aerobic and form membranes on the surface of 
the wort, producing only carbon dioxide and water and destroying the alcohol produced by other yeasts. 

1 The strengths of the worts for different types of beer are : 9 to 10 Balling for light beers ; 12 to 13 for 
draught beers (Schenkbier) ; 15 to 20 for double beers (Bock or Salvator beer) ; and up to 25 for table beers. 



FERMENTATION 



173 



able, and rigorous precautions and disinfection are resorted to, it is very difficult to 
prepare top-fermentation beer, whilst the low temperature required for bottom fer- 
mentation can be attained at any season of the year by refrigerating plant. Bottom 
fermentation gives beers of a more constant type, since the mother -yeast from succes- 
sive fermentations does not become contaminated so easily as, and hence requires renewal 
less frequently than, with top fermentation. 1 

When a large amount of yeast is added to a wort the fermentation is initiated and 
completed more rapidly ; with small quantities the same result is obtained, but after a 
longer time, so that there is more danger of contamination. Usually 250 to 300 grms. 
of pressed yeast are used per hectolitre of wort rather more for strong worts. 

Especially with top, but also with bottom fermentation, it is most important that all 
instruments, vessels, and rooms should be kept clean and disinfected. For this purpose 
boiling water is used and also dilute solutions of hydrofluoric acid, ammonium fluoride, 
ammonium fluosilicate, calcium bisul- 
phite, and calcium hypochlorite. In 
all cases, however, great care must be 
taken to remove the disinfectant com- 
pletely with abundant supplies of hot 
water, in order that the yeast may not 
be injured. Chloride of lime is elimi- 
nated by rinsing first with bisulphite 
solution and then with hot water. 
Even traces of bisulphite (sometimes 
added during mashing to prevent the 
action of lactic ferments) must be 
completely eliminated, otherwise, 
during the alcoholic fermentation, 
which is a process of reduction, they 
may yield hydrogen sulphide and so 
give a bad taste and odour to the 
beer. (Bacteria capable of producing 
hydrogen sulphide sometimes develop 
in beer.) 

Whatever system of fermentation is 
used, it is always divided into two 
phases : the primary or vigorous, and 
the secondary. The primary fermenta- FIG. 167. 

tion begins 12 or 24 hours after 

pitching, when the yeast has grown to some extent at the expense of the dissolved 
oxygen, and continues for 3 or 4 days in the case of top fermentation or for 10 to 12 
days with bottom fermentation ; considerable quantities of carbon dioxide are developed, 
these forming a dense, white, frothy head on which can be seen brownish spots of hop 
resin or agglutinated bacteria. In top fermentation, this first head is removed, the next 
darker one being collected for pitching purposes. 

In the bottom fermentation system and in large modern breweries in general, in order 
that the yeast may be kept as pure as possible, the pitching is carried out in the manner 
described on p. 127 for distilleries. 

1 With top fermentation, the type and taste of the beer are determined by the united activity of a number 
of different yeasts and bacteria which are present in given equilibrated proportions, these becoming modified 
as contamination increases. When the yeast is renewed, the pure yeast naturally gives a different taste to the 
beer, and this inconvenience cannot be avoided by preparing a mixture of yeasts and bacteria similar to that 
normally present in the partially contaminated top fermentation. New pure yeasts are less resistant to con- 
taminating surroundings than old ones are. 

Attempts are made to-day to keep the fermentation pure as long as possible by the use of good, hops, the 
resins of which exert an agglutinating and paralysing action on the bacteria, so that these can be removed from 
the tun with the first scum forming on the surface of the fermenting wort ; the purer yeast of succeeding heads 
is then collected for pitching subsequent worts. When the collection of the yeast is delayed, that of the Frohberg 
type increases. With the object of maintaining the cultures naturally pure and constant, Effront has proposed 
the addition of abietinic acid a component of lupulin and of colophony to agglutinate and render innocuous 
the bacteria in fermenting worts (see also p. 141). Thus, after elimination of the bacteria with the first scums, 
purer yeast can be collected and washed with pure water or, better, with water containing a little hydrofluoric 
acid or ammonium fluoride (5 to 10 grms. per hectolitre), which attacks the bacteria, but not the yeast. It cannot, 
however, be^denied that, in general, washing produces considerable weakening of yeast, which can be reinvigorated 
by preliminaryjgrowth in sterilised, unhopped wort. 




174 ORGANIC CHEMISTRY 

During the primary fermentation, a considerable quantity of heat is evolved, and to 
prevent the temperature exceeding 22 to 25 in top or 7 to 8 in bottom fermentation, 
attemperating coils,, through which cold water (top) or brine (bottom) passes, are used to 
cool the fermenting wort (F, Fig. 167). Each fermenting vat is provided with a slate, 
&c., on which are noted, each day, the temperature and the specific gravity of the wort ; 
the attenuation should reach 58 to 62 per cent, in the primary fermentation and 70 to 
75 per cent, in the secondary fermentation, in order that the beers may keep in the warmer 
rooms of the consumers. 1 When the vigorous fermentation is ended, the head falls and 
almost disappears, carrying to the bottom of the wort the suspended yeast ; in this way 
the secondary fermentation is started, this being allowed to proceed for 15 to 20 days 
in the trade casks placed in cellars at 10 to 12 (for top fermentation) ; the beer is then 
cleared, filtered, and sold. In bottom fermentation, on the other hand, the secondary 
fermentation is completed in large tuns pitched inside (-see later) ; these are not quite filled 
and are kept for 1 to 3 months in cellars maintained continually at to 2, where the 
beer acquires the desired attentuation and its characteristic flavour. The yeast which is 
deposited in the fermenting vessels can be collected, pressed (p. 125) and sold to bakers or 
small brewers. 

In some breweries the carbon dioxide is now drawn off from the fermenting vats, which 
are fitted with covers, by pumps and, after being passed through potassium permanganate 
solution to purify it, the gas is then liquefied (see vol. i, p. 382) ; it can be either utilised 
in the brewery itself or sold. 

The fermenting vessels and the storage casks are constructed of oak or pitch-pine. 
The use of glass vats has been proposed, as these retain the pure flavour of the beer ; such 
a vat to hold 42 hectols. costs about 40. The cellars have walls and floor of concrete 
(1 metre higher than the first aqueous border of the subsoil) so that they can be washed 
when necessary ; the roof is of brickwork. These cellars are furnished with draughts 
to remove the carbon dioxide, with double doors (always on the north side) to prevent the 

1 Determinatiort of the Attenuation and of the Apparent and Real Extracts of Beer. The apparent 
extract is deduced from the density of the well-shaken (to remove CO 2 ) beer and the corresponding number 
of degrees Balling (see p. 167). The real extract is deduced from the specific gravity (and Balling's tables) of the 
beer freed from alcohol by evaporating it to one-third of its volume and making the residue up to the original 
volume. The original extract of the wort may he calculated with moderate accuracy by adding to the real extract 
the amount of alcohol (determined as in wine, p. 147) multiplied by 1-92. 

The degree of real attenuation (A) is referred to 1 hectolitre of wort and indicates how many parts per 100 of 
the extract of the wort are transformed into alcohol and carbon dioxide : it is obtained by means of the following 
formula : 

A = ^^ X 100 

where D represents the percentage of extract in the wort and d the percentage of real e.rtract of the beer. 

In practice, the percentage of extract is sometimes replaced by the degrees Balling, but the results thus obtained 
are not very exact. If we make D = 15 Balling and d = 5, the real attenuation becomes : 

15-5 
A = x 100 = 66-66 per cent. 

15 

But it cannot be denied that Balling degrees refer to kilos of sugar or of extract in 100 kilos of solution, so 
that a wort showing 15 Balling (sp. gr. 1-0615) contains 15 kilos of extract per 100 kilos of wort, or 15-922 kilos 
(i.e. 15 X 1-0615) in a hectolitre of wort ; the beer, free from alcohol, showing 5 Balling, has a sp. gr. 1-020, and 
1 hectolitre contains 5-100 kilos of extract, so that 10-822 kilos of extract have been fermented and the true 

10-822 
attenuation is TcTooo x ^ ~ ^'* " 



Practical brewers find it more convenient, in considering the degree of attenuation of a wort, to calculate the 

D-d 
degree of apparent attenuation (A') from the apparent extract of the beer d bymeans of the formula, A = x 100; 

for example, a wort of 16 Balling has the sp. gr. 1-0658 and 1 hectolitre contains 17-05 kilos of extract, while 
the beer, with 7 Balling of apparent extract, has the sp. gr. 1-0281, corresponding with 7-20 kilos of extract per 

17.05 _ 7-20 
hectolitre. The apparent attenuation is hence - -r-rr - X 100 = 57-9 per cent, per hectolitre. 

L i *Ui> 

The attenuation can be deduced in a rather less exact manner if instead of degrees Balling are used degrees of 
the legal densimeter (i.e. the figures in the second decimal place of the specific gravity, a value of 1-063 for the 
latter thus corresponding with 6-3 on the legal densimeter). In the above example, 16 Balling corresponds with 
sp. gr. 1-0658, hence with 6-58 on the densimeter ; similarly, 7 Balliog corresponds with 2-81 densimeter degrees. 
Hence the apparent attenuation is given by : 

A' = - - X 100 = 57-3 per cent. 
6-58 

which differs little from the value calculated above from the degrees Balling, and is sufficiently exact for practical 
purposes. Hence, both for real and apparent attenuation, Balling's tables can be dispensed with, it being sufficient 
to determine the specific gravity. It should be noted that the lesjal density expresses the weight of wort 
contained in the volume occupied hy 1 kilo of water measured t 17-5, 



NATHAN-BOLZE PROCESS 



175 



entry of warm air from outside and with electric lighting so that windows, which dissipate 
the cold may be avoided. The vats and casks are raised 50 to 60 cm. from the ground and 
are inclined slightly forward so that they can be emptied completely and easily cleaned 
from outside. Along the ceiling run pipes for the circulation of cold brine (bottom 
fermentation), which maintain a temperature below 60 in the fermentation cellars 
and one of to 2 in the lager cellars. 

Ten or fifteen days before the beer is run off from the lager vessels which have been 
several times filled up to avoid contact of the beer with the air and consequent danger 
from acetic ferments the 
bung-hole is tightly closed so 
as to supersaturate the beer 
under slight pressure with 
carbon dioxide, which is still 
developed more or less feebly 
according to the state of ma- 
turity of the beer. If a beer 
contains, say, O'l to 0-2 per 
cent, of C0 2 before the bung- 
hole is closed, it will sub- 
sequently contain six or seven 
times that proportion. 

Nathan-Bolze Rapid 
Process (Ger. Pat. 135,539, 
1900). This process was tested 
on an industrial scale in 1904 
in the Fermentation Institute 
at Berlin, and gave satisfac- 
tory results. But the applica- 
tion of the process has not 
progressed as rapidly as was 
hoped for a process which 
allows of mature beer being 
prepared in 8 or 10 days, and 
works under conditions of 
sterilisation formerly attain- 
able only in the laboratory or 
in the manufacture of spirit 
by the amylo -process (p. 129). 
The hot, sterile wort from the 
copper passes into a large 
hermetically sealed, sterile 
vessel of enamelled iron (a 
special resistant enamel being 
employed) surrounded by an F IG> igg. 

iron jacket through which 

water can be passed. These vessels have a capacity of 125 hectols. or more and are 
called Hansena vessels. They are provided with powerful stirrers (Fig. 168), which keep 
the wort in continual motion during the fermentation and thus accelerate the transforma- 
tion of the maltose into alcohol and carbon dioxide. 

After the temperature of the wort has been lowered to 50 by passing water through 
the jacket and the diminution of pressure (owing to the condensation of steam) compen 
sated by the admission of sterilised air, the latter (which has served also to aerate th 
wort) is replaced by carbon dioxide, the cooling being continued to 10. The pure yeast 
is then introduced through suitable pipes, the mass being slightly stirred at intervals 
of an hour. The gas developed is removed in order to hasten the fermentation, and is 
washed with permanganate, part of it then being compressed (see p. 174). The carbon 
dioxide which is not compressed is utilised to remove the new beer flavour from beer 
already fermented in the Hansena vessels ; the gas is passed in at the bottom (after removal 
of the yeast sediment) at the ordinary temperature, the mass being continually stirred 




176 ORGANIC CHEMISTRY 

meanwhile, it being the carbon dioxide which effects the elimination from the boor of the 
volatile products to which the disagreeable taste and odour of new beer are due. The 
gas issues from the top of the vessel, passes to the purifiers and is again conducted through 
the beer, this process being continued for 10 hours on end. The primary fermentation 
is finished in less than 3 days, and, after the passage of gas through the beer is completed, 
the temperature is lowered to and the beer saturated for 24 hours with slightly com- 
pressed carbon dioxide. The beer is finally filtered and delivered to the trade casks, 
where it keeps well even in the hot weather. 

Such a process, simple, rapid, and economical (the cost of the beer being diminished 
by about 2s 6d. per hectolitre), although it does not give a very delicate flavoured beer, 
should be suitable to hot countries and to small breweries. Several European breweries 
already work on these lines and recently (1907) one has been constructed at Milan to employ 
a modification of the Nathan patent, consisting of a system intermediate to the old process 
with open fermenting vessels and that devised by Nathan ; in this case enamel] ed iron 
vessels are used both for the primary fermentation and for the maturation (3 to 4 weeks). 
These vessels cost about 1 for each hectolitre of capacity. 

If to the Nathan process is added the Meura system of mashing (1891) which has 
rendered the preparation of the wort as simple as possible by mashing the finely ground 
malt in a horizontal cylinder fitted with stirrers so that the mash can be rapidly cooled or 
heated and wort ready for passing to the filter-press and thence to the copper can be 

obtained in an hour it will be understood 
how the manufacture of ordinary beer has 
been shorn of those practical and theoretical 
difficulties long regarded as insurmount- 
able. 

RACKING OF BEER. Beer is delivered 
to the consumer in bottles and in casks, and 
should be perfectly bright, cold, and super- 
saturated with carbon dioxide. To render it 
bright, the old method of clarification with 
gelatine or of filtration through bags has now 
FIG. 169. been largely replaced by the use of the filter- 

press, which acts more rapidly and yields 

brilliant beer. The filtration is carried out in suitable frames through filter-cloths or, 
better, through finely divided cellulose (such as is used in paper-making) under a pressure 
of about half an atmosphere. These filter-presses are the same in principle as, and little 
different in form from, those which are used for the filtration of saccharine liquids and 
are described in the section on Sugar. (In England, beer in cask is clarified by mixing 
with the beer a small quantity of finings, which consist of isinglass " cut " or dissolved 
in an acid, such as tartaric, sulphurous, &c. ; these finings are gradually deposited on the 
bottom of the cask and carry down with them any suspended protein substances, hop- 
resins, &c.). Bottling is to-day carried out with all the care employed in the preparation 
of sparkling wines. A few lines may be devoted to the preparation of beer-casks, since 
the methods employed are peculiar to the brewing industry. 

In order that beer for retail consumption may retain its flavour, it must be kept cool 
and saturated with carbon dioxide up to the moment when it is drawn off into the customers' 
glasses, and for this purpose the use of liquid carbon dioxide with the arrangement shown 
in vol. i, p. 389, is well adapted. 

RESINING OR PITCHING OF CASKS. The keeping of beer sound depends 
largely on the cleanliness of its surroundings and of the vessels in which it is stored. Hence 
the casks, returned empty from the customers, are first well scrubbed and washed both 
inside and outside with water under pressure by means of automatic plant (Fig. 169), 
and are then disinfected by means of formalin vapour or other antiseptics, or, better still, 
by pitching the internal surface with natural or artificial resins, which should be transparent 
and have a melting-point of about 50 ; in this process, which was first used in Bavaria, 
and is nowadays largely employed all over the Continent, aromatic resins are no longer 
used, mixtures of colophony with other residues from the distillation of turpentine being 
prepared by fusion and then rendered more elastic by the addition of resin oil (10 per 
cent.). To free the casks from the old resin and coat them again every time they are 




PASTEURISATION 



177 



returned to the brewery, they are heated inside by means of air supplied from a Roots 
blower, B (Fig. 170), and heated bypassing through red-hot coke, the hot air being forced 
into the casks through the tubes, D, for 5 minutes. The old pitch is discharged and the 
new pitch (about 200 to 250 grms. per hectolitre), fused and heated to 250, introduced 
into the sterile cask. The bung-hole is then closed, the cask rotated automatically for a 




FIG. 170. 

few minutes, the excess of pitch poured out, and the rolling of the cask continued until 
it is cold. The lager -vessels used for the maturation of the beer are treated in a similar 
way. 

PASTEURISATION. Beer, more than wine, is subject to numerous changes and 
diseases (turbidity due to inferior materials, incomplete saccharification or excess of 
proteins ; acidity caused by acetic or lactic acid ; stinking fermentation produced by 




FIG. 171. 

various bacteria, &c.), and it is difficult to remedy these inconveniences except by improve- 
ment in the methods of working. In order that beer may remain unchanged when kept 
for a long time in bottle or when sent to hot places, it is advisable to pasteurise it. The 
bottles are tightly stoppered and placed in vessels containing cold water, which is then 
gradually heated to a maximum of 60 to 65, this temperature being maintained for 10 
minutes ; the vessels should be covered so as to avoid danger from breakages. The 
water-bath is subsequently allowed to cool slowly to the ordinary temperature. Top- 
fermentation beers are rarely pasteurised, as they sometimes acquire an unpleasant flavour 

II 12 



178 



ORGANIC CHEMISTRY 



under this treatment ; bottom-fermentation beers, however, undergo no change and keep 
good even for ten years. 

In large breweries, very efficient pasteurising apparatus is employed, the bottles being 
moved automatically in suitable vessels in which the water moves in the opposite 
direction. 

Of the many improved forms in use at the present time, the Gasquet circular type is 
shown in Pig. 171. Here the chambers are filled successively with baskets of bottles, 
which are raised by suitable cranes. The water, at a gradually increasing temperature, 
is drawn from each chamber by means of a tube communicating with a pump, heated by 
a central thermo-syphon, and then passed on to the succeeding chamber. A bell rings 
every five minutes as a signal for the bottles of a cool chamber to be removed and replaced 
by fresh ones. 

The bottles are made of a special glass, which diminishes the proportion of breakages 
to less than 1 per cent. 

ALCOHOL-FREE BEER. A proposal has recently been made to manufacture 
beer containing no alcohol by treating wort directly at with yeast which has previously 
been, subjected to special treatment effecting the destruction of almost all of the zymase 
but not that of the peptase and other proteolytic enzymes ; the carbohydrates hence give 
no alcohol, the proteins alone being decomposed. These yeasts remove the flavour of 
fresh wort, the beer being used before alcoholic fermentation begins (Ger Pat. 180,128). 

COMPOSITION AND ANALYSIS OF BEER. The most varied types of 
beer are found in different countries, and of each type there are usually the 
two qualities pale and dark. 1 The density varies from 1-010 to 1-030, and 
the amount of alcohol usually from 3-5 to 4-5 per cent, by volume, although 
export beers often contain 5 to 5-5 per cent, of alcohol, and certain special 
beers still more. The amount of extract also varies considerably, being as 

1 The compositions of some of the best-known beers are as follow : 





Alcohol 


Extract 


Ash 


Real 

attenuation 




per cent, 
by vol. 


per cent, 
by vol. 


per cent, 
by vol. 


per cent, 
by vol. 


Pale Berlin beer .... 


3-91 


4-85 


0-14 


60-50 


Berlin lager beer ..... . 


4-00 


6-15 


0-20 


54-70 


Export Bavarian beer . . . . . 


4-78 


1067 


0-29 


45-44 


Munich Spaten beer (at Munich) . 


3-23 


6-61 


0-28 


48-40 


,, ,, (at Milan) . . 


5-23 











Salvator beer' . . . 


4-64 


9-08 


0-28 


49-00 


Spaten table beer . . . 


7-0 


10-35 





57-40 


Bock ..... 


4-20 


7-10 





54-20 


white beer .... 


3-51 


4-73 





59-58 


Vienna lager beer .... 


3-62 


6-01 





54-50 


Pilsen beer ...... 


3-47 


4-97 





59-00 


North of France beer .... 


3-20 


4-04 





61-20 


Amsterdam beer ..... 


4-30 


7-0 





36-40 


Brussels Iambic ..... 


5-94 


3-30 





78-00 


Belgian faro ..... 


4-33 


5-1 





62-80 


Bass's pale ale ..... 


6-15 


6-87 





64-00 


Scotch pale ale ..... 


8-50 


10-90 





59-9 


Dublin stout ..... 


7-23 


6-15 





70-64 


London porter .:.... 


5-40 


6-00 


' 


63-3 


American beer ..... 


5-89 


6-45 





63-15 


Milan beer : Pilsen type ... 


3-92 


5-43 


0-21 


57-91 


,, Munich type ... 


3-50 


5-58 


0-20 


54-63 


Porretti beer (Varese) .... 


3-98 


5-66 


0-22 


57-45 


Italia beer (made at Milan by the modified Nathan- 










Bolze process) ....... 


4-78 


6-00 


0-22 


59-43 



The real attenuation (or degree of fermentation, see p. 174) is calculated by multiplying the percentage of nlcohol 
by 1-92 (= d'), and adding to this product the extract of the beer, d ; this gives the extract, D, contained in the 

D d 
wort prior to fermentation and then the attenuation or percentage of extract fermented = X 100. 

Some English breweries make stout from a mixture of 65 per cent, of pale malt, 10 per cent, of black malt (for 
colour), 10 por cent, of caramelised malt and sometimes 10 per cent, of cane-sugar and 5 per cent, of maize. This 
very dark beer is attenuated to a relatively small extent, and retains a full, sweet taste, this being partly due to 
the almost entire absence of gypsum in and the small total hardness of London water ; these beers also contain few 
hops. Export stout is made from worts having gravities as high ag 25 Balling, whilst porter is lighter jn character, 
J'he pale beers of Berlin are made with a gggd proportion (75 per 00nt-) Q* malted wheat, 



BEER STATISTICS 179 

much as 12 per cent, for certain types of beer ; for ordinary beers it lies 
between 5 and 6 per cent. (1 per cent, being maltose). The proportion of ash 
is generally less than 0-3 per cent. The amount of carbon dioxide dissolved 
varies from 0-15 to 0-40 per cent. 

The analysis qf beer is carried out in a similar manner to that of wine (p. 157), but 
the carbon dioxide is eliminated by heating the beer to 40 and shaking for several minutes 
before the specific gravity and acidity are determined ; the latter does not exceed 0-3 per 
cent, and is expressed as lactio acid (1 c.c. N/10-alkali = 0-009 grm. lactic acid) or as 
cubic centimetres of normal alkali used per 100 c.c. of beer. To avoid frothing during the 
distillation of the alcohol, 1 a little tannin is added. The nitrogenous substances are deter- 
mined on the extract of 40 c.c. of the beer by Kjeldahl's method (p. 10), the proportion of 
nitrogen being multiplied by 6-25 to give the corresponding amount of proteins. The 
reducing sugar is determined by means of Fehling's solution and is calculated as maltose 
(see Note, p. 167). 2 

STATISTICS. In Italy the brewing industry has never been in a flourishing condition, 
owing to the abundance and cheapness of wine possibly more commonly drunk than water. 
The beer manufactured from remote epochs in Italy was made by the top -fermentation 
process and was of poor quality ; it did not keep well in summer, was stored carelessly 
by the retailers and was consumed for only about a couple of months in the year 
close to where it was produced. Technical improvements have been introduced tardily, 
but nowadays the industry is largely concentrated into a few large breweries using the 
most modern methods and controlled by technical experts from other countries. 

About one -half of the beer imported into Italy is supplied by Austria -Hungary, about 
one -third by Germany, and one -tenth by Switzerland : 

PRODUCTION, IMPORTATION, AND CONSUMPTION OF BEER IN ITALY 

Consumption 

Production Imports Total Per head 

hectols. hectols. in cask hectols. litres 

1880 . ". 116,000 . . 46,900 . . 163,000 . . 0-57 

1890 . . 160,900 . . 99,500 . . 260,000 . . 0-86 

1894-95 . . 95,500 .. 60,000 .. 156,000 .. 0-50 

1900 . . 154,000 . . 54,750 . . 209,000 . . 0-66 

1903 .' . 185,000 . . 70,000 . . 255,000 . . 0-79 

1904 . . 220,000 . . 80,000 . . 300,000 . . 0-92 
1905-06 . . 304,000 . . 90,000 . . 394,000 . . 1-20 
1906-07 . . 360,000 .. 94,494 .. 455,000 .. 1-50 
1907-08 . . 400,000 .. 95,213 .. 495,000 .. 1-60 
1908-09 . . 473,000 .. 88,100 .. 561,000 .. 1-80 
1909-10 . . 563,000 . . 89,737 . . 651,000 . . 2-00 

1 The proportion of alcohol can be calculated indirectly by means of the formula, A = (s/S) -4- 8, where 
A indicates the percentage of alcohol, s the specific gravity of the beer, S the specific gravity of the beer freed 
from alcohol and made up to the original volume ; the alcohol Table (p. 148) gives the percentage by weight 
corresponding to the value of s/S and division of this percentage by S gives the true percentage of alcohol. 

8 The determination of sulphurous add (only traces are allowed in beer) derived from sulphites or sulphurous acid 
added to preserve the beer, is effected by distilling 200 c.c. of the beer, previously acidified with 5 c.c. of syrupy 
phosphoric acid, in a current of carbon dioxide and passing the distillate through 50 c.c. of iodine solution (5 grms. 
I + 7-5 grms. KI made up to 1 litre with water) ; the iodine solution is then acidified with hydrochloric acid, 
boiled to expel excess of iodine and precipitated with barium chloride, the filtered, washed, and ignited barium 
sulphate being weighed ; multiplication of this weight by 1-372 gives the amount of SO 2 per litre of beer. For 
the detection of boric and, 100 c.c. of beer are evaporated to dryness and the residue calcined ; a little sulphuric 
acid and alcohol are then added to the resulting ash and the mixture ignited and stirred ; the appearance of a 
green colour at the edges of the flame indicates the presence of boric acid. The quantitative determination of 
boric acid is difficult and is only rarely carried out, Rosenbladt and Gooch's method being then used. 

For the detection of fluorides, sometimes (although prohibited) added as preservative, 100 c.c. of the beer, 
rendered alkaline with ammonium carbonate, are boiled, mixed with 3 to 4 c.c. of calcium chloride solution, boiled 
again for 5 minutes and filtered, the residue being washed and calcined in a platinum crucible. One cubic centi- 
metre of concentrated sulphuric acid is then added and the crucible, covered with a watch-glass partly coated 
with paraffin wax, gently heated. 1 In presence of fluorides, the glass is attacked in the unprotected parts. 

The degree of attenuation or of fermentation is calculated as indicated in the Note on the preceding page. 

Adulteration with salicylic acid is detected by acidifying 100 c.c. of the beer with 5 c.c. of hydrochloric acid and 
shaking with 50 c.c. of ether and 50 c.c. of light petroleum. The ethereal solution is separated and evaporated to 
dryness, the residue being taken up in water and filtered. If the liquid gives a violet coloration with a little 
dilute ferric chloride solution and a red one with MiKon'9 mgent (aqueous mercuric nitrate containing a little 
nitrous acid), the presence of salicylic acid is certain, 

Saccharin \ determiped by evaporating an. ethereal fjrfrapt obtained as abpve, dissolving fte resjdup i s a Jltyfe 



180 ORGANIC CHEMISTRY 

The consumption of beer in Italy takes place mostly in the towns of the north and 
centre, and the average consumption per head in Milan, Turin, or Rome is at least ten 
times that for the whole country. 

The production of beer in Japan was 362,000 hectols. in 1907 ; 294,100 in 1908 ; 271,500 
in 1909, and 280,000 in 1910. 

The production of beer in other countries in 1900 was as follows : Germany, 67,000,000 
hectols. or 118 litres (in 1907, 70, and in 1910, 64 litres) per head. England, 59,000,000 
hectols. (57,000,000 or 150 litres per head in 1909). Austria -Hungary, 20,000,000 hectols. 
(72 litres per head) or 19,000,000 in 1909. Belgium, 14,000,000 hectols. (213 litres per head). 
France 9,000,000 hectols. (25 litres per head ; but here, too, the consumption is localised, the 
annual consumption per head in Lille being 360 litres) ; in 1909 France produced 11,000,000 
hectols. The United States, 48,000,000 hectols. (63 litres per head) in 1900 and 70,000,000 
in 1909. Spain, about 1,000,000 hectols., and Russia, 6,200,000 hectols. in 1909. 

In 1900, Germany, with 10,000 breweries, produced twice as much beer as in 1880, 
and in 1885 exported 1,500,000 hectols. One large brewery in Germany makes more 
beer than the whole of Italy consumes. (Italy has 93 breweries at the present time.) 

In 1881, England produced 45,000,000 hectols. ; Austria -Hungary, 12,000,000 ; Belgium 
9,000,000 ; France, 8,000,000 ; Switzerland, 1,000,000 (now 1,500,000), and the United 
States, 19,000,000. 

The world's production of beer in 1910-11 was 271,000,000 hectols. 

In Italy the brewing tax was 5fd. up to 1891, when it was raised to ll^d. (causing a 
temporary diminution in the consumption at that time) per saccharometer degree per 
hectolitre, measured with the decimal saccharometer at 17'5 on the wort from the cooler, 
an allowance of 12 per cent, being made for loss during the subsequent operations ; the 
tax varied from a minimum of 115d. to a maximum of 184d. per hectolitre, according to 
the strength of the beer. Imported beer pays 29d. more, or the importers can demand the 
tax to be levied on the extract degrees, these being increased by twice the number of 
alcohol degrees. The exchequer collected 180,000 in 1905-6 and 211,800 in 1906-1907 
as tax of manufacture. 

In Germany beer costs about 12s. per hectolitre, or rather more with the extra taxation 
of 1910. In Italy the cost is about 32s. (that imported from well-known breweries about 
40s. per hectolitre). 

ALCOHOLS HIGHER THAN ETHYL 

PROPYL ALCOHOLS, C 3 H 8 O. The two isomerides theoretically possible are known : 

(1) Normal, CH 3 CH 2 CH 2 OH (propanol-1 or ethylcarbinol). This can be obtained 
from fusel oil (p. 122) by fractional distillation or from its bromo -derivative. It has an 
agreeable odour, b.pt. 97, sp. gr. 0-804, and is readily soluble in water. On oxidation it 
gives propionic acid, which proves its constitution. 

(2) Sec. or Iso-Propyl Alcohol, CH 3 -CH( OH)- CH 3 (propanol-2 or dimethylcarbinol), is 
a colourless liquid, b.pt. 81, sp. gr. 0-789. It is obtained from isopropyl iodide and hence 
indirectly from glycerol, or by reducing acetone with sodium amalgam, the constitution 
attributed to it being thereby confirmed. 

BUTYL ALCOHOLS, C 4 H 10 O. The four isomerides, predicted by theory, are 
known : 

(1) Normal Butyl Alcohol, CH 3 -CH 2 - CH 2 -CH 2 - OH (l>utanol-\ or propylcarbinol), is a 
liquid, b.pt. 117, sp. gr. 0-810, and has an irritating odour ; 12 vols. of water at 22 dissolve 
only 1 vol. of it, this being separated from the solution by the addition of a soluble salt. 

sodium carbonate solution, evaporating in a silver dish and fusing the residue with solid caustic soda ; the white 
mass is dissolved in water, the solution acidified with hydrochloric acid, and the sulphuric acid (derived from 
the sulphonic group of the saccharin) precipitated quantitatively as barium sulphate. The weight of the latter, 
multiplied by 0-785, gives the weight of saccharin. 

Caramel, rjdded to colour the beer is recognised by shaking 20 c.c. with about 30 to 40 grms. (i.e. until saturated) 
of solid sodium sulphate and 60 c.c. of 05 per cent, alcohol. If the lower liquid is markedly coloured and forms a 
greenish brown deposit, the presence of caramel is indicated ; beer .containing no caramel becomes decolorised 
and gives only a greenish or dark greenish brown deposit if it contains coloured malt. 

Picric acid is detected by evaporating a litre of the beer to a syrupy consistency, extracting with boiling absolute 
alcohol, filtering and evaporating the alcoholic liquid, dissolving the residue in water, adding a few drops of hydro- 
chloric acid and heating for an hour with a few strands of wool ; if the latter are coloured yellow, picric acid is 
present. 

Extraneous bitter substances are tested for by evaporating 2 litres of beer to half its volume and precipitating 
the residue in the hot with lead acetate ; the hot liquid is filtered rapidly and the lead then precipitated with 
ammonium sulphate and filtered off. The filtrate should have no bitter taste. 



BUTYL, AMYL, AND HIGHER ALCOHOLS 181 

It is found in fusel oil and can be obtained by fermenting glycerol or mannitol (yield 
8 to 10 per cent.) with Bacillus butylicus (contained in the excreta of cows). It can also 
be prepared synthetically by the various general processes (p. 104). Its constitution is 
indicated by its syntheses and by the possibility of transforming it into normal butyric 
acid by oxidation. 

(2) Secondary Butyl Alcohol, CH 3 CH 2 CH(OH) CH 3 (butanol-2 or ethylmethylcarbinol) 
is a liquid with an intense, peculiar odour, b.pt. 100, sp. gr. 0-808. It can be obtained by 
treating the tetrahydric alcohol, erythritol, C 4 H 6 (OH) 4 , with hydriodic acid or by the 
interaction of normal butylene and hydriodic acid and hydrolysis of the resulting iodide. 

/ITT 

(3) Isobutyl Alcohol, ^^^CH CH 2 OH (methylpropanol), is termed also butyl alcohol 



of fermentation, since it abounds in the fusel oil of potatoes, from which it can be extracted 
by forming the corresponding iodo -compound. It is a colourless liquid, b.pt. 107, sp. gr. 
0-806, and has a characteristic alcoholic smell. Its constitution is determined by the 
fact that, on oxidation, it yields isobutyric acid, the constitution of which is known. 

C*TT 

(4) Tertiary Butyl Alcohol, r , T4 - 3 >C(OH)-CH 3 (trimethylcarbinol or methyl-2-propanol), 
Or 3 

occurs in small proportion in fusel oil, and can be prepared by the action of hot 75 per cent. 
sulphuric acid on isobutylene, which thus takes up 1 mol. of water. When pure, it forms 
rhombic prisms or plates, m.pt. 25-5, sp. gr. 0-786 (solid), b.pt. 83. On oxidation it gives 
acetic acid, acetone, and carbon dioxide. 

AMYL ALCOHOLS, C 6 H U .OH. The eight isomerides theoretically possible are 
known, the most important being : 

(1) Normal Amyl Alcohol, CH 3 - CH 2 CH 2 - CH 2 CH 2 - OH (pentanol-l), b.pt. 138, 
sp. gr. 0-817, is of little importance, and is obtained by reducing normal valeraldehyde or 
by the other general methods. 

(2) Amyl Alcohol of Fermentation, 3 >CH-CH 2 - CH 2 - OH (methyl-3-butanol-I or 

L>1 3 

isobutylcarbinol), is a liquid, b.pt. 130, sp. gr. 0-810, and is solid at 134. It imparts 
its characteristic smell and burning taste to fusel oil, in which it abounds. It is to this 
alcohol that the poisoning effect of spirits is principally due. It occurs naturally in Roman 
chamomile oil. 

(3) Active Amyl Alcohol, /Lr^CH CH 2 OH (methyl-2-butanol-l or 2-methylbutan- 

L>rL 3 

l-ol), boils at 128, has the sp. gr. 0-816, and is found with the amyl alcohol of fermentation. 
It contains an asymmetric carbon atom (see p. 19) and is laevo -rotatory, whilst the halogen 
compounds and the valeric acid derived from it are dextro-rotatory ; also the dextro- 
isomeride of this acid yields a laevo -rotatory iodide. 

PTT 

(4) Tertiary Amyl Alcohol, ^TT 3 >C( OH)- CH 2 -CH 3 (methyl-2 -butanol-2 or amylene 

CM 3 

hydrate or dimethylethylcarbinol) is an oily liquid with a faint odour of mint. It boils at 
102 and is prepared from amylene by the indirect addition of water under the influence of 
sulphuric acid. It exerts a soporific action. 

HIGHER ALCOHOLS. Of these may be mentioned : Primary normal hexyl alcohol 
or hexanol, CH 3 - [CH 2 ] 4 -CH 2 -OH (14 of the 18 hexyl alcohols predicted by theory are 
known), can be obtained from caproic acid, C 6 H 12 2 , and is found as butyric and acetic 
esters in the ethereal oil of the seeds of Heracleum giganteum and in the fruit of Heracleum 
spondylium : it boils at 158 (under 740 mm. pressure), and has a specific gravity of 0-820. 
Caproyl or isohexyl alcohol, (CH 3 ) 2 : CH CH 2 CH 2 CH 2 OH, b.pt. 150, is f ound in vinasse 
and in fusel oil. Heptyl (or oznanthyl) alcohol, C 7 H 16 O ; of the ^38 possible isomerides, 
13 are known. Normal octyl alcohol, C 8 H 18 O, is contained in Heracleum spondylium and 
H-eracleum giganteum ; secondary octyl alcohol (or capryl alcohol or methylhexylcarbinol) is 
formed on distilling castor oil. Other higher alcohols are obtained by reducing the corre- 
sponding aldehydes with zinc dust and acetic acid ; they are almost solid, like paraffin wax. 
Cetyl or normal hexadecyl alcohol, C^H^O, combined with palmitic acid, forms the principal 
component of sperm oil. Ceryl alcohol (cerotin), C 26 H 53 OH, occurs as cerotic ester in Chinese 
wax and in wool-fat ; it melts at 76 to 79. Melissyl or myricyl alcohol, C 30 H 61 OH, 
is found as the palmitic ester in beeswax and carnauba wax and is obtained free by saponi- 
fication with alcoholic potash. 



182 



II. UNSATURATED MONOHYDRIC ALCOHOLS 



These are similar to the saturated alcohols, but, as they contain one or .two double 
linkings, they behave like the olefines and diolefines in taking up two or four atoms of 
hydrogen, halogens, &c., to give saturated compounds. If they contain a triple linking, 
C ^ CH, they form explosive metallic compounds, as does acetylene (p. 91 ). 

VINYL ALCOHOL, CH 2 : CH-OH (Ethenol), appears to be present in commercial 
ether, but it has never been isolated, attempts to synthesise it leading, as is the case with 
other similar compounds, to an isomeride acetaldehyde, CH 3 -CHO ; the formation of 
the latter is explained by the addition of a molecule of water to the alcohol, and immediate 
loss of a molecule of water from the compound thus formed. 

ALLYL ALCOHOL, CH 2 : CH-CH 2 -OH (Propenol), is a liquid of pungent odour, 
b.pt. 97, and readily soluble in water. It is formed in small quantity in the distillation of 
wood, but is more easily obtained by heating glycerol at 26 with oxalic acid and a little 
ammonium chloride. Cl, Br, CN, and HC10 can be added on to it directly, but not H. 
When cautiously oxidised, it takes up O and H 2 O, giving glycerol or even acrolein (ally! 
aldehyde) and acrylic acid, which shows it to be a primary alcohol. 

CITRONELLOL, C 10 H 2 oO, is found in attar of roses. 

PROPARGYL ALCOHOL, CH C-CH 2 -OH (Propinol), is a liquid with a pleasant 
odour, lighter than water, b.pt. 114. 

GERANIOL, C 10 H l8 Oor(CH 3 ) 2 : C : CH-CH 2 -CH 2 -C(CH 3 ) : CH-CH 2 -OH, is a pleasant- 
smelling oil, b.pt. 121 under 17 mm. pressure. It is obtained from geranium oil, and 
on oxidation gives citral (the corresponding aldehyde) which occurs in mandarin oil and 
in essences of orange and lemon and to a very considerable extent (60 per cent.) in 
verbena oil. 

III. POLYHYDRIC ALCOHOLS 
(a) DIHYDRIC ALCOHOLS OR GLYCOLS, C W H 2 ,XOH) 2 

Substitution of two hydrogen atoms joined to different carbon atoms 
by two hydroxyl groups gives dihydric alcohols, containing two alcoholic 
groups. It is not, however, possible to have two hydroxyl groups united to 
the same carbon atom although similar compounds are known for the ether 
derivatives known as Acetals (see later) since even if they could be formed 
they would immediately lose a molecule of water, forming aldehydes or 
ketones. 

The dihydric alcohols, owing to their sweet taste, were called Glycols by 
Wurtz, who prepared them by transforming a dihalogenated hydrocarbon into 
the corresponding diacetyl-ester by means of silver acetate and then saponi- 
fying the diacetyl compound either by baryta or sodium hydroxide or by 
boiling with water and lead oxide or sodium carbonate solution : 

CH 2 Br CH 2 .0-COCH 3 

1 +2CH 3 -COOAg = 2AgBr+ I 

CH 2 Br CH 2 -0-COCH 3 

Ethylene bromide Diacetylglycol 

CH 2 .0-COCH 3 CH 2 -OH 

+ 2KOH = 2CH 3 -COOK + I (glycol) 

CH 2 -0-COCH 3 CH 2 -OH 

A special group of glycols, the pinacones, containing two adjacent tertiary 
alcohol groups (=C-OH), are formed by reducing the ketones with sodium 
and water, or, better, together with isopropyl alcohol, by electrolysing a dilute 
solution of sulphuric acid and acetone, the latter being reduced at the 
negative pole : 

CH 3 -C(OH)-CH 3 
3CH 3 CO CH 3 + H 4 = CH 3 CH(OH) CH 3 + | 

CH 3 -C(OH)-CH 3 



POLYHYDRIC ALCOHOLS 183 

this pinacone (2 : 3-dimethyl-2 : 3-butandiol), melts at 38, boils at 172 and 
crystallises with 6H 2 O. When distilled with dilute sulphuric acid, it is 
transformed into pinacotine, (CH 3 ) 3 C-CO- CH 3 , with separation of H 2 
and transposition of an alkyl group. 

The glycols have an almost oily appearance ; their solubility and sweetness 
increase with the molecular weight ; the specific gravity and boiling-point are 
much higher than those of the monohydric alcohols with equal numbers of carbon 
atoms. The hydroxyl groups of the glycols behave like those of monohydric 
alcohols, so that the glycols can give rise to ethers and esters, alkoxides (sodium, 
&c.), halogen compounds (e.g. the chlorohydrins), aldehydes and acids, besides 
which they may give up 1 mol. of H 2 forming anhydrides. 

ETHYLENE GLYCOL (Ethan-1 : 2-diol), C 2 H 4 (OH 2 ), is a dense liquid, b.pt. 198, 
and, on oxidation, yields glycollic acid, CO 2 H CH 2 OH and oxalic acid, C0 2 H C0 2 H. 

PROPYLENE GLYCOLS. Two isomerides are known : a-Propylene Glycol, 
OH.CH 2 -CH(OH)-CH 3 (propan-1 -. 2-diol), boils at 188 and is formed in the distillation 
of glycerolwith sodium hydroxide. It contains an asymmetric carbon atom and, by the 
action of certain ferments, the Isevo -rotatory isomeride can be isolated. /3 -Propylene 
Glycol boils at 216 and is formed by the bacterial decomposition of glycerol, as well as by 
the usual synthetical methods. 

In the higher glycols, when the two hydroxyl groups have four carbon atoms between 
them (y-glycols), water is readily separated and furan derivatives, analogous with pyrrole 
and thiophene compounds, formed. 

(6) TRIHYDRIC ALCOHOLS, C,,H 2w . 1 (OH) 3 

These are colourless, dense liquids with a sweetish taste and readily soluble 
in water ; they contain at least three carbon atoms and three hydroxyl groups, 
and are hence capable of forming three series of esters by combination with a 
monobasic acid. 

GLYCEROL, C 3 H 5 (OH) 3 , or OH-CH 2 -CH(OH)-CH 2 -OH (Propantriol), 
was discovered by Scheele in 1779. Chevreul and Braconnot (1817) found it 
as a component of all oils and fats. Its formula and constitution were estab- 
lished later (Pelouze, Wurtz, and Berthelot). It occurs abundantly in nature, 
not in the free state, but combined with higher fatty acids in the form of esters 
(glycerides), which form the fats and oils ; these contain 9 to 11 per cent, of 
combined glycerol. 

It exists free in rancid fats and is formed in small proportions in the fer- 
mentation of sugar (all wines contain 0-98 to 1-67 per cent.). Industrially 
glycerol is obtained principally from factories where fats are decomposed 
(stearine- and soap-works). Synthetically it can be obtained by transform- 
ing propylene (from isopropyl iodide), by means of chlorine in the hot, into 
dichloropropane, C 3 H 6 C1 2 , which, with iodine chloride, gives the trichloro- 
derivative C 3 H 5 C1 3 ; the latter, when heated with water at 170, gives glycerol : 

CH 2 C1-CHC1-CH 2 C1 + 3H 2 O = 3HC1 + OH-CH 2 -CH(OH)-CH 2 -OH. 

This formation of glycerol and also that by the oxidation of allyl alcohol, 
CH 2 : CH-CH 2 -OH, demonstrate the constitution of glycerol. On the other 
hand, it is possible to prepare glycerol synthetically from the elements by way 
of acetylene, acetaldehyde (p. 91), acetic acid, acetone (by distillation of 
calcium acetate), isopropyl alcohol (by reduction), propylene, and thence, as 
above to glycerol (Friedel and Silva). 

PROPERTIES. Glycerol (also termed glycerine) is an oily, colourless, dense 
(sp. gr. 1-265 at 15) liquid, with a sweet taste ; it is very hygroscopic and 
dissolves in all proportions in water and alcohol, heat being developed on mixing 
58 parts of glycerol with 42 parts of water. 

It is insoluble in ether and chloroform ; it dissolves to the extent of 5 per 



184 



ORGANIC CHEMISTRY 



cent, in dry acetone and to a greater degree in aqueous acetone. It boils at 
290 with partial decomposition, but it can be distilled unchanged in a vacuum 
(at 10 mm. pressure it boils at 162). It crystallines at 40 or at a higher 
temperature if it contains water ; the separated crystals melt only at 22. 

When heated for a long time at 130 to 160 in presence of sulphuric acid, 
glycerol loses one or more molecules of water, giving anhydrides or ethers 
of glycerol or polyglycerines (A. Nobel, 1890) ; W. Will (1904) arrived at the 
same result by heating glycerol for 7 to 9 hours at 290 to 295 and distilling 
off the water formed. This treatment yields about 60 per cent, of diglycerol, 
C 3 H 5 (OH) 2 -0-C 3 H 6 (OH) 2 , and a little tri- and polyglycerols ; all these pro- 
ducts can be esterified like glycerol and yield, e.g. tetranitrodiglycerine, which 
does not congeal even at 20 and has an explosive power like trinitroglycerine 
(see also C. Claessen, Ger. Pats. 181,754 and 198,768, 1907). According to 
U.S. Pats. 978,443 (1910) and 13,234 (1911), glycerol readily polymerises 
when heated at 275 in presence of 0-5 to 1-0 per cent, of sodium acetate, 
70 per cent, being polymerised in an hour. 
- When it is heated rapidly and strongly it decomposes, yielding partly 

acrolein with the characteristic pungent odour. Also when heated with P 2 5 

or KHS0 4 , it loses 2H 2 0, giving acrolein, CH 2 : CH- CHO. 

One hundred parts of glycerol dissolve the following quantities of mineral 

salts : 98 of sodium carbonate, 60 of borax, 50 of zinc chloride, 40 of potassium 

iodide, 10 of boric acid, 50 of tannin ; bromine, ammonia, ferric chloride, &c., 

are also dissolved. 

Glycerol has the refractive index 1-476 at 13 and in aqueous solution the 

index varies proportionally with the dilution. By means of Lenz's table, the 

concentration of glycerol solutions can be determined from either the specific 

gravity or the index of refraction : 



Per- 
centage of 
glycerol 


Degrees 
Bailing, 
Beck, 
Gerlach 


Sp. gr. at 
12 to 14 


Index of 
refraction 
at 12-5 to 
12-8 


Per- 
centage of 
glycerol 


Degrees 
Baum, 
Beck, 
Gerlach 


Sp. gr. at 
12 to 14 


Index of 
refraction 
at 12-5 to 
12-8 


98 


30-1 


1-2637 


1-4729 


48 


16-2 


1-1265 


1-3979 


96 


29-6 


1-2584 


1-4700 


46 


15-5 


1-1210 


1-3950 


94 


29-1 


1-2531 


1-4671 


44 


15-0 


1-1155 


1-3921 


92 


28-7 


1-2478 


1-4642 


42 


14-3 


1-1100 


1-3890 


90 


28-2 


1-2425 


1-4613 


40 


13-6 


1-1045 


1-3860 


88 


27-7 


1-2372 


1-4584 


38 


13-0 


1-0989 


1-3829 


86 


27-1 


1-2318 


1-4555 


36 


12-3 


1-0934 


1-3798 


84 


26-6 


1-2265 


1-4525 


34 


11-5 


1-0880 


1-3772 


82 


26-1 


1-2212 


1-4496 


32 


11-0 


1-0825 


1-3745 


80 


25-6 


1-2159 


1-4467 


30 


10-3 


1-0771 


1-3719 


78 . 


25-1 


1-2106 


1-4438 


28 


9-6 


1-0716 


1-3692 


76 


24-5 


1-2042 


1-4409 


26 


9-0 


1-0663 


1-3666 


74 


24-0 


1-1999 


1-4380 


24 


8-3 


1-0608 


1-3639 


72 


23-5 


1-1945 


1-4352 


22 


7-6 


1-0553 


1-3612 


70 


23-0 


1-1889 


1-4321 


20 


6-9 


1-0498 


1-3585 


68 


22-3 


1-1826 


1-4286 


18 


6-1 


1-0446 


1-3559 


66 


21-6 


1-1764 


1-4249 


16 


5-6 


1-0398 


1-3533 


64 


21-0 


1-1702 


1-4213 


14 


4-9 


1-0349 


1-3507 


62 


20-3 


1-1640 


1-4176 


12 


3-8 


1-0297 


1-3480 


60 


19-8 


1-1582 


1-4140 


10 


3-4 


1-0245 


1-3454 


58 


19-2 


1-1530 


1-4114 


8 


2-8 


1-0196 


1-3430 


56 


18-6 


1-1480 


1-4091 


6 


2-1 


1-0147 


1-3405 


54 


18-0 


1-1430 


1-4065 


4 


1-3 


1-0098 


1-3380 


52 


17-4 


1-1375 


1-4036 


2 


0-7 


1-0049 


1-3355 


50 


16-9 


1-1320 


1-4007 











GLYCEROL 185 

Glycerol has the interesting property of preventing the precipitation of 
various metallic hydroxides (i.e. it keeps them dissolved) ; for instance, in 
presence of glycerol, potassium hydroxide does not precipitate salts of chromium, 
copper, &c. With alkalis it forms slightly stable soluble alkoxides. It does 
not reduce silver or cupric salts, and hence cannot contain aldehyde groups ; 
it is not coloured by concentrated sulphuric acid or by sodium hydroxide on 
boiling. The halogens act on glycerol, not as substituting, but as oxidising 
agents. It inverts cane-sugar and renders starch soluble ; 100 parts of glycerol 
and six of starch at 190 give starch soluble in water, and the starch can be 
separated from the glycerol, when cold, by precipitation with alcohol. 

Like the other polyhydric alcohols (glycols, erythritol, and its isomerides, 
also glucose and its isomerides galactose, &c. but not cane-sugar, quercitol 
or dextrin) glycerol, when added in sufficient quantity, transforms the alkaline 
reaction of borax solutions in an acid reaction, thus allowing of the determina- 
tion of boric acid and borax by titration. 

Under the action of certain schizomycetes, glycerol yields normal butyl 
alcohol, butyric acid and, partly, ethyl alcohol. 

Being a trihydric alcohol, glycerol is able to form esters of three types 
(mono-, di- and tri-), according as one, two, or three hydroxyl groups are 
replaced by inorganic or organic acid residues. In this way the glycerides can 
be regenerated ; for example, when excess of stearic acid is heated with glycerol 
at 200 under reduced pressure until no more water separates, tristearin is 
formed. 

When cautiously oxidised, glycerol forms first glyceric acid, OH-CH 2 - 
CH(OH)-COOH, which undergoes further oxidation to tartronic acid, 
COOH-CH(OH)'COOH, so that it is proved that glycerol contains two 
primary alcohol groups, (-CH 2 -OH); also, as tartronic acid still exhibits 
alcoholic characters, it must contain a secondary alcohol group. The con- 
stitution of glycerol is hence completely proved. 

USES OF GLYCEROL. The majority of the glycerol manufactured is 
used for the preparation of nitroglycerine and hence of dynamite (see later). 
It is also used to give body to light wines (termed Scheelisation, after Scheele, the 
discoverer of glycerol). It is employed in the manufacture of liqueurs, syrups, 
preserves, and sweetmeats, since it is sweet and dense, and, to some extent, 
anti-fermentative. It is added to chocolate, tobacco, cosmetics, textiles to be 
dressed, and leather goods, since it does not dry and keeps them soft or pliable. 
It is also used in extracting from flowers and herbs delicate perfumes which 
would undergo change if extracted by distillation. 

It is employed as a non-congealing and lubricating liquid (a solution of 
$p. gr. 1-13) in gasmeters ; for greasing iron objects to prevent them from 
rusting ; for making copying-ink, soap, and shoe-polish ; for preserving 
anatomical preparations, &c. 

INDUSTRIAL PREPARATION. Glycerol is almost exclusively obtained as a 
secondary product in the treatment of fats. Until the year 1885 only the aqueous residues 
of stearine works were worked up (the fats are decomposed with lime, sulphuric acid, steam, 
or ferments), but nowadays almost all the alkaline lye of soap factories (where the fats 
are treated directly with caustic soda and then with salt) 1 are utilised. 

Of the 9 to 11 per cent, of glycerol contained in fats, 8 to 10 per cent, can be recovered 
(only 4 per cent, when the decomposition is effected by sulphuric acid, the maximum yield 
being obtained when water or ferments are used). 

The treatment of the dilute solutions of crude glycerol varies with their origin : soap- 
lyes (which are sometimes concentrated in the soap-works and sold to the glycerol refiners) 

1 These lyes have an alkaline reaction and, on analysis, one of them gave the following results : water, 61 per 
cent.; glycerol, 16-5 per cent, salts; 22 per cent, (eight-tenths of which were NaCI, one-tenth Na 2 SO4, and 
one-thirtieth Na 2 CO,). The specific gravity varies from 3 to 7 B6., and the proportion of glycerol usually 
from 6 to 12 per cent. 



186 



ORGANIC CHEMISTRY 




are treated with 0*1 to 0*2 per cent, of lime or ferrous sulphate and mixed by means of an 
air-jet ; the liquid is decanted, slightly acidified with hydrochloric acid and skimmed ; 
a small quantity of aluminium sulphate is then added, the liquid being decanted, rendered 
slightly alkaline, passed through a filter-press and concentrated in open boilers furnished 
with stirrers until sodium chloride begins to separate ; subsequent concentration to the 
sp. gr. 28 Be. is carried out in a vacuum, the salt deposited being gradually removed. This 
crude glycerol contains 85 to 90 per cent, of glycerol and 1 per cent, of salts, and has a dark 
yellow or brownish colour. Sometimes the alkali is removed from the soap lyes by adding a 

little resin and boiling, so that the 
resin soap formed is carried to the 
surface and can be decanted (to be 
utilised by adding to ordinary soap). 
The free lime may also be pre- 
cipitated with an oxalate or with 
carbon dioxide. The concentration 
is not carried out in open vessels, 
as, when the aqueous solutions are 
vigorously boiled, the steam given 
off carries away appreciable quan- 
tities of glycerol. The concentration 
is hence carried to a certain point 
FIG. 172. in an apparatus (Fig. 172 shows the 

Droux apparatus and Fig. 173 that 

of Morane), fitted with rotating coils or hollow discs, in which steam under pressure circu- 
lates. The apparatus is covered in and the steam from the solution .issues rapidly through 
a tube communicating with an aspirator. When the density reaches 18 to 20 Be. the 
solution is decanted or filtered and then further concentrated in a vacuum to 27 to 28 Be. 

In some cases the glycerol thus obtained, while still boiling, is decolorised by adding 
animal charcoal and filtering through a filter-press. This glycerol always contains a small 
quantity of dissolved salts. To purify it, its temperature is raised to 110 to 120 by means 
of superheated steam, the acids or more volatile products being thus eliminated. It is 
then distilled with superheated steam at 170 to 180, at which temperature all the 
pure glycerol passes over. This is rectified 
in one apparatus to 22 Be. and in a 
second, under diminished pressure and wit h 
superheated steam, to 28 Be., at wh:'ch . 
concentration almost all the salt separate' . 
The vacuum distillation is sometiirto 
effected by a triple-effect apparatus (Pick 
type, see vol. i, p. 453 ; also section c n 
Sugar), with which it is easy to remove 
the salt as it separates without interrupt- 
ing the distillation. 

These forms of apparatus for purifica- 
tion and distillation are named after their 
inventors (Hagemann, Scott, Jobbins, van Ruymbeke, Lehmann, Heckmann, &c.). 

The Heckmann process consists in distilling the aqueous glycerine, already concentrated 
to beyond 20 Be., in a boiler, A (Fig. 174), into which steam superheated to 200 to 
220 and under half an atmosphere pressure is passed by means of a perforated coil. In 
order to prevent the scum being carried over with the steam and glycerol, a perforated 
disc, a, fitted with a vent-pipe is fixed two-thirds of the way up the boiler. The vapours 
issue by the pipe B, and are condensed in the reservoir, C, which is heated to 80 to 90 
with indirect steam circulating in the jacketed bottom, D. Above the reservoir is a 
rectifying column, with a dephlegmator, K, similar to, but. much lower than, that used for 
the rectification of alcohol (see p. 136). 

During the distillation, a slight vacuum is maintained in the whole apparatus by means 
of a suction pump, V, so that principally water-vapour and only a little glycerol are evolved 
from the reservoir, C. The glycerol vapour separates in the column and returns to the 
reservoir, whilst the condenser, M , condenses only the water-vapour, which is controlled 




FIG. 173. 



PURIFICATION OF GLYCEROL 



187 



by its density, colour, and taste in the test-glass, N, and is then collected in the tank, 0. 
In C the glycerol finally reaches a concentration of 95 to 99 per cent. 

The rectifying column is sometimes replaced by a series of communicating, vertical 
copper tubes (Fig. 175) which fractionally condense the glycerol- and water-vapours from 
the boiler, B (heated partly by d : rect fire), into which passes steam from v, superheated 




in the furnace, T. By means of the pump, Z, a vacuum is maintained in the whole apparatus, 
so that, as the distillation proceeds, fresh glycerine from the reservoir, A, can be drawn 
into the boiler. In the first cylinder or condensing tube, which soon reaches a temperature 
of 100, almost pure glycerol separates, whilst in the succeeding tubes, cooled only by the 
surrounding air, more and more dilute glycerine and finally water separate. Below each 
tube is a horizontal cylinder, these serving to collect the glycerols of different concen- 
trations, some of which are subjected to redistillation. In this way is obtained the best 
dynamite, glycerine, which must have a specific gravity of 1-263 (98 to 99 per cent.), and 
should not contain lime, sulphuric acid, chlorine, or arsenic. 

The final decoloration may also be effected by sodium hydrosulphite. Very pure 




FIG. 175. 

glycerol has been obtained by maintaining it at for some time and then inducing crystal- 
lisation by a few pure crystals obtained separately by cooling to 40 (Kraut's process). 
The degree of purity is increased by a second crystallisation. 

Purification by an osmotic process has also been attempted but with unsatisfactory 
results. 

During the last few years the glycerine liquids from the biological or catalytic decom- 
position of fats (see section on Fats) have also been worked up : they are first neutralised 
or, better, rendered slightly alkaline with milk of lime and, after being left for some time, 
the liquid is decanted or filtered off, concentrated to 15 Be. in vacuo, again allowed to 
stand to deposit a further quantity of lime, decolorised by passing through a carbon filter 
and again concentrated to 28 Be. 

Various attempts have also been made to recover the glycerine from the waste liquors 
from the manufacture of alcohol, but as yet without much success (Ger. Pats. 114,492, 



188 ORGANIC CHEMISTRY 

125,788, 129,578, 141,703, and 147,558). Separation of glycerine by dialysis does not 
give good results. 

STATISTICS AND PRICES. In 1890, the world's production of crude glycerine 
amounted to 26,000 tons from candle factories and 14,000 tons from soap factories, the 
amounts due to the principal nations being : France, 6000 tons (candles), 3500 tons (soap) ; 
Germany, 3000 and 2000 ; England, 1200 and 5500 ; Italy, 180, &c. 

In 1900 the production rose to 80,000 tons (equally divided between soap and candle 
factories) and Germany, with a production of about 10,000 tons, exported 2730 tons (value 
about 140,000) in 1900 and 1580 tons in 1909, against importations of 5373 tons in 1908 
and 3530 tons in 1909. In 1890 France exported 3856 tons (value 156,000), in 1900 about 
7450 tons (value 308,000), and in 1909 as much as 7000 tons out of a total production of 
12,000 tons ; 9000 tons were made at Marseilles, where the most important refinery produces 
more than 2000 tons per annum. The French exportation is now directed especially to 
the United States (more than 4000 tons in 1910). According to the official statistics (!) 
Italy produced 190 tons of distilled glycerine (worth 8660) in 1905 and 215 tons (value 
12,040) in 1908 ; the imports were 198 tons in 1907 and 1908, 160 tons in 1909 and 270 
tons in 1910; and the exports 833 tons in 1908, 1145 tons (worth 59,540) in 1909, and 
1763 tons (value 126,920) in 1910. 

In 1910 Spain produced 2500 tons of glycerine and exported 893 tons. In 1905 the 
United States produced 23,000 tons (1,040,000), of which 13,500 tons were obtained from 
soap-works ; the imports amounted to 16,000 tons in 1909 and to more than 20,000 tons in 
1910. England exported 10,500 tons (one-half in the crude state) in 1909 and about 12,500 
tons (1,040,000) in 1910 ; in 1911 the output was 16,000 tons, one-half of which was refined. 
Two main qualities of glycerine are distinguished : * (a) Crude glycerine from the 
candle or soap works ; (b) Refined glycerine, which is subdivided into : pale, white, for 
dynamite, and chemically pure. 

In 1905-1909 the price of No. II dark brown crude glycerine at 24 Be. was 30s. 6d. per 
quintal, and at 28 Be. 36s. per quintal ; for the light brown quality, 46s. 6d. per quintal 
at 28 Be., and for the pale at 28 Be. 4. Yellow refined at 28 Be. cost 93s. ; 
white refined No. I, 96s. at 28 Be. and 108s. at 30 Be. ; free from lime for soap, 
5 at 28 and 108s. at 30 Be. Finally the purest double distilled glycerine for nitro- 
glycerine at 31 Be. cost 6 per quintal. At the beginning of 1910 these prices were 
increased by 25 per cent, and towards the end of 1910 by 50 per cent, or even 70 per cent. 
At the beginning of 1911 they were still higher mainly owing to the large amount required 
in North America for making dynamite for the Panama Canal and other public works. 

C. TETRA- AND POLY-HYDRIC ALCOHOLS 

These are usually sweet, crystalline substances which decompose near their 
boiling-points. They are distinguished one from another by the crystalline 
forms of their phenylhydrazine derivatives. 

1 Tests for Glycerine : the crude, pale at 28 Be., contains 0-5 per cent, of ash and is not rendered 
turbid by HC1, and only faintly so by lead acetate ; that separated from sulphuric acid saponifications, besides 
having a bad smell and taste, gives 3 to 5 per cent, of ash and 84 to 86 per cent, of glycerine, a turbidity (fatty 
acWs) or precipitate being produced by HC1 or lead acetate. The glycerine to be used for nitroglycerine and 
dynamite is subjected to the following tests : the water is calculated from the loss in weight of 20 grms. heated 
for 10 hours at 100 and for a few hours at a slightly higher temperature. Five grammes, after being heated in a 
platinum dish at 180 until no further evolution of vapour takes place, are weighed, and should then undergo no 
further diminution in weight when again heated for a short time ; it is then ashed in the usual way and the ash 
tested for metals and salts. Glycerine for nitroglycerine should have been distilled at least once, should not 
contain sugar or fatty acids, should have a neutral reaction and should contain no lead, calcium, or other metals or 
foreign metalloids ; only traces of Cl, As, and Fe are allowed : the specific gravity should exceed 1-262. The purest 
glycerine (puriss.) does not contain more than 0-03 per cent, of ash and as much organic impurity, and for dynamite 
these two should not exceed 0-25 per cent. Oxalic acid is detected by neutralising with ammonia, acidifying 
with acetic acid and precipitating with CaCl,. The glycerine content is determined from the density (the air- 
bubbles being removed by heating), use being made of the Table on p. 184 ; in Germany a special Berthelot scale is 
used indicating one degree higher than the Baume' scale, 26 Berthelot corresponding with a specific gravity of 1-210, 
28 with 1-230, 29 with 1-240, and 30 with 1-250. The index of refraction is determined at the temperature 
indicated in the Table. In many cases the glycerine is estimated directly by means of the acetyl number (see 
(succeeding Note), but the method in which the glycerine is oxidised by hot permanganate and potassium hydroxide 
to oxalic acid and the latter precipitated as calcium oxalate should be rejected. The fairly rapid Hehner- 
Richardson-Jaffe method is used more successfully : the glycerine is destroyed with dichromate and sulphuric 
acid, and the amount of dichromate used up (or, according to Gautter and Schulze, how much CO 8 is evolved) 
measured by titration with sodium thiosulphate, or, better, ferrous ammonium sulphate. This method assumes 
that the glycerine contains no chloride, nitrate, or extraneous organic matter ; these impurities can, in any case, 
be eliminated by means of silver oxide (chlorides), and lead acetate and calcium carbonate (organic matter), 
decoloration being then effected by heating with animal charcoal. 



POLYHYDRIC ALCOHOLS 189 

They do not reduce Fehling's solution and hence differ from the carbo- 
hydrates, but are derived from these by reduction. 

The valency of an alcohol is given by the number of alcoholic hydroxyls it 
contains, and hence by the number of monobasic acid residues it can fix to form 
a neutral ester. Acetic anhydride serves well for this purpose, the hydrogen 
atoms of the hydroxyl groups being replaced each by an acetyl group, CH 3 CO : 1 

C 6 H 8 (OH) 6 + 6(CH 3 -CO) 2 O = 6CH 3 -COOH + C 6 H 8 (0-CO-CH 3 ) 6 . 

Mannitol Hexacetylmannitol 

Esters can also be prepared with bromobenzoic acid, the bromine in the 
resultant product being determined and the number of hydroxyl groups 
deduced therefrom. Well-defined compounds are also formed with benzal- 
dehyde and are employed in separating the constituents of different mixtures. 

ERYTHRITOL(Butantetrol),OH-CH 2 -CH(OH)-CH(OH)-CH 2 -OH, is found in nature 

in the free state in Protococcus vulgaris, and as orsellinic ester (erythrin) in lichens and algae. 
It forms crystals, m.pt. 112, b.pt. 330, and is slightly soluble in alcohol and insoluble in 
ether. It is obtained by decomposing rf-glucose or synthetically from crotonylene, and its 
constitution is deduced from the fact that it yields secondary normal butyl iodide on 
reduction with hydriodic acid. A similar reaction takes place with the higher polyvalent 
alcohols with normal chains. The four possible stereoisomerides are known, the most 
common being the one now described which is optically inactive. 

PENTA-ERYTHRITOL has the formula C(CH 2 -OH) 4 , and melts at 253. 

ARABITOL, C 5 H 7 (OH) 5 (Pentahydroxypentane), crystallises in acicular prisms, 
m.pt. 102, has a sweet taste and is formed by reducing the corresponding sugar, arabi- 
nose, with nascent hydrogen ; reduction of xylose similarly yields xylitol. 

MANNITOL, C 6 H 8 (OH) 6 (Hexanhexol), occurs abundantly in the vegetable kingdom 
(the larch, sugar-cane, Agaricus integer containing 20 per cent, of mannitol, &c.), but espe- 
cially in the manna ash (Fraxinus ornus), the dried juice of which forms ordinary wanna; 2 

1 In this way is determined the so-called acetyl number which is so widely used in the analysis of fats and oils. 
With these, the test is made on the insoluble fatty acids obtained by saponifying 40 to 50 grms. of the fat with 
40 c.c. of KOH solution (sp. gr. 1-4) and 40 c.c. of alcohol, this mixture being heated for half an hour on the 
water-bath, after which it is diluted with a litre of water and boiled for three-quarters of an hour in an open 
beaker to eliminate the alcohol. The liquid is acidified with sulphuric acid and boiled until the fatty acids separate 
in a transparent condition, when they are removed with a tapped funnel, washed twice with hot water and dried in 
an oven at 100 to 105". To determine the acetyl number, a few grammes of the substance containing the hydroxyl 
groups (or about 20 grms. of hydroxylic fatty acids) are treated with two or three times their volume of acetic 
anhydride and a few drops of concentrated sulphuric acid (formerly in place of the sulphuric acid fused sodium 
t acetate, in quantity equal to the acetic anhydride, was used, the mixture being heated for two hours on the water- 
bath in a reflux apparatus). The mass heats spontaneously, and in a few minutes acetylation takes place ; it 
is then allowed to cool, calcium carbonate being added to precipitate the sulphuric acid and the liquid filtered. 
The filtrate is distilled or evaporated to separate the acetate in a liquid or crystalline condition. 

In the case of the fatty acids, the filtrate is, however, diluted with 600 to 700 c.c. of water and boiled for 
30 to 40 minutes in an open beaker to remove the acetic acid, a slow current of CO 2 being passed into the bottom 
of the liquid to prevent bumping. The supernatant liquid is then siphoned from the acetyl compound, which is 
boiled with another 500 c.c. of water and so on, this operation being repeated until the washing water no longer 
has an acid reaction. The acetylated derivative is then collected on a filter, washed and dried in an oven. 

Of this compound, 0-5 to 1 grm. is dissolved in pure, neutral alcohol, and the solution heated for 45 minutes on 
the water-bath in a 150 c.c. flask with a definite volume (30 to 50 c ; c.) of seminormal alcoholic potash. When 
cold, the liquid is titrated with seminormal hydrochloric acid in presence of phenolphthalein to determine the 
excess of alkali which has not taken part in the splitting of the acetic ester. 

One hydroxyl group for every grm.-mol. of substance corresponds with 56 grms. of KOH fixed. With the 
fatty acids, which contain also the carboxyl group, the procedure is as follows : 3 to 4 grms. of the acetyl derivative 
are dissolved in pure, neutral alcohol and the acidity of the carboxyl group (acetyl acid value) determined by 
titration with N/2-alkali ; the neutralised liquid is boiled with a known volume in excess of N/2-alcoholic potash 
for a short time on the water-bath, retitration with N/2-hydrochloric acid given the excess of alkali not combined 
with acetyl groups. The alkali combined (after the first neutralisation), expressed in mgrms. of KOH per 1 grm. 
of acetyl compound gives the acetyl number. With the fatty acids the sum of the acetylated acid number and 
the acetyl number is termed the acetyl saponiftcation value. From the acetyl number (N), the molecular magnitude 

56,100 
(M ), of the alcoholic substance can be deduced by the formula : M - - 42. 

1 Manna is extracted more particularly from Fraxinus ornus and Fraxinus rotundifolia, which are widespread 
in Sicily and Calabria and from which it readily flows through long vertical incisions made in summer and autumn. 
It seems to occur in the rising sap before this reaches the leaves and is thought by some to be produced by enzyme 
actions. Crude, commercial manna contains 12 to 13 per cent, of water, 10 to 15 per cent, of sugar, 32 to 42 
per cent, of mannitol, 40 to 41 per cent, of mucilaginous substances, organic acids and nitrogenous matter, 1 to 2 
per cent, of insoluble substances and 1 to 2 per cent, of ash. Australian manna (from Myoporum platycorpum) 
contains as much as 90 per cent, of mannitol. 

The manna tree grows in fertile, rocky soiljind is incised iu its tenth year and in the following 10 or 15 years. It 



190 ORGANIC CHEMISTRY 

from this alcohol extracts pure mannitol, which can be decolorised by repeated treatment 
with charcoal. In manna it was discovered by Proust in 1806. It is obtained synthe- 
tically by reducing fructose or glucose : C 6 H 12 O 6 + H 2 = C 6 H 14 O 6 . 

The optically inactive, laevo- and dextro-rotatory forms are known, the last being the 
most common ; the optical activity is slight but is rendered more apparent by the addition 
of borax. When heated it loses water giving anhydrides (mannitan, C 6 H 12 5 , and mannide, 
C 6 H 10 O4) ; in a vacuum it distils unchanged. 

One hundred parts of water dissolve 16 parts by weight of mannitol at 16. 

From alcohol it crystallises in triclinic acicular prisms and from water in large rhombic 
prisms having a sweet taste and melting at 160. 

Stereoisomeric with mannitol is DULCITOL, C 6 H 8 (OH) 6 , which occurs in a number 
of plants and in Madagascar manna. It forms sweet, monoclinic prisms, m.pt. 188, and is 
almost insoluble in water, even in the hot. Synthetically it can be prepared by reducing 
lactose and galactose. It is optically inactive even in presence of borax. 

Another stereoisomeride of mannitol is sorbitol, which melts at 104 to 109, or at 75 
when crystallised with 1H 2 O. It can be obtained synthetically by reducing d-glucose 
or ^-fructose. In presence of borax it shows a slight dextro-rotation. 

Other stereoisomerides are TALITOL and IDITOL ; these isomerides are usually 
separated by means of the acetals they form with benzaldehyde. 

DD. DERIVATIVES OF THE ALCOHOLS 

A. DERIVATIVES OF MONOHYDRIC ALCOHOLS 
i. ETHERS 

These are generally formed by eliminating 1 mol. of water (for example, 
by concentrated sulphuric acid or by hot hydrochloric acid) from 2 mols. of 
alcohol, which condense to form 1 mol. of ether in the same way as 2 mols. of 
an acid give an anhydride : 

C 2 H 5 OH _ TT o , C 2 H 5 \ O 
CH 3 -OH CH 3 / L 

Ethers are not formed by secondary or tertiary alcohols. The first term of the 
series, methyl ether, is gaseous, and the succeeding terms become liquid and 
then solid as the molecular weight increases, the ethereal odour of the first 
members being gradually lost. 

is then cut back and the new branches incised in the seventh year and the succeeding 10 or 15 years. It is 
then again cut back, this procedure being continued for 80 or 100 years. J One hectare with 4500 trees gives as 
much as 100 kilos of manna per annum. It is harvested in August and September. 

Manna is used as a mild purgative for children. It has a sweetish taste, is soluble in' water or alcohol, and, 
besides mannitol, contains various sugars such as stachyose and mannatrwse. 

To extract the mannitol, the crude manna is dissolved in half its weight of water containing white of egg. 
The solution is boiled for a few minutes and strained, and the filtered mass, solidified by cooling, pressed in bags, 
or, better, centrifuged and washed at the same time with a large quantity of cold water. It is redissolved in 
water and the solution boiled with animal charcoal, filtered under pressure, crystallised and centrifuged. The 
mother-liquors are used to dissolve fresh quantities of the crude manna. The fineness of the crystals depends on 
the concentration and on the temperature of the air ; in some cases the crystallisation is disturbed by continually 
stirring the mass. 

Sometimes the manna solutions are first subjected to lactic fermentation, by which means considerable quantitie 
of calcium lactate are obtained ; the mannitol is then extracted from the residual liquors. 

Mannitol is not fermented by beer-yeast, but with chalk and sour cheese it gives a considerable amount of 
alcohol, volatile acids, carbon dioxide, and hydrogen. When cautiously oxidised with nitric acid, it forms 
d-mannose and d-fructose, whilst with the Sorbose bacterium it gives only the latter sugar. 

Mannitol has a slight laevo-rotation ( 0-15) which is increased by alkali and changed in sign by borax. It 
dissolves in 6-5 parts of water at 18, in 80 parts of 60 per cent, alcohol at 15, or in 1400 parts of absolute alcohol ; 
it is insoluble in ether. 

Manna in casks costs 3s. to 5s. per kilo ; assorted, 1. 7d. ; in lumps, 9i</v The average. price of manna (from 
Cefalu) on the Genoa Exchange has gradually risen from about 2s. Id. in 1901 to about 4s. 7d. in 1910, when pure 
crystallised mannitol cost 7. to 10s. per kilo. The best qualities of manna are those from Cefalu, Gerace, and 
Smauro ; of inferior quality is the Capaci variety, which is produced also at Cinisi, Belmonte, Castellamare del 
Golfo, &c. The Sicilian production, which represents almost the entire production of the world, was about 3600 
quintals in 1900, 7000 in 1902, 5100 in 1905, 6900 in 1906, 4550 in 1908, and less than 3000 (owing to the bad 
season) in 1910. The exports were 2320 quintals in 1907, 1776 in 1908, 2582 (value? 36,000) in 1909. About 
8000 quintals per annum are treated for the extraction of mannitol about 1000 quintals, of wljieh onjy one-third 
pr one-fourth IB consumed in Italy, 



ETHERS 191 

The empirical formulae of the ethers show them to be isomeric with the 
alcohols, but their constitution results from Williamson's synthesis, according 
to which they are obtained by the action of a sodium alkoxide on the halogen 
derivative of an alcohol : 

C w H 2w+1 ONa + IC,,H 2 ,, +1 = Nal + C^^.O-aH^ 

If in the sodium alkoxide the sodium were not united to the oxygen but 
directly with carbon, this reaction would give an alcohol and not an ether ; 
indeed, if sodium ethoxide were NaCH 2 CH 2 - OH, it would, with methyl iodide, 
give propyl alcohol : CH 3 I + NaCH 2 CH 2 OH = Nal + CH 3 CH 2 CH 2 OH. 
But, in reality, methyl ethyl ether and not propyl alcohol is obtained, this 
proving the constitution of the metallic alkoxides and of the ethers, in which 
all the hydrogen atoms are equivalent. 

The interaction of silver oxide with alkyl halides (see p. 17) also leads to 
the formation of ethers : 2C 2 H 5 I + Ag 2 = 2AgI + C 2 H 5 -0-C 2 H 5 . 

If the alkyl radicles of an ether are similar, it is a simple ether, e.g. ethyl ether, 
C 2 H 5 -0-C 2 H 5 , whereas if the radicles are different, the result is a mixed ether, 
e.g. methyl ethyl ether, C 2 H 5 - 0- CH 3 . 

Sabatier, Senderens, and Mailhe (1909-1910) obtained ethers of different types, some 
mixed and of the aromatic series, by passing the superheated vapours of alcohols (250 to 
350) over metallic oxides (titanium, thorium, tungsten, or, best of all, aluminium). The 
yield is quantitative, no ethylene hydrocarbons being formed as is the case when sulphuric 
acid is used. The process is continuous and pseudo-catalytic, unstable aluminium alkoxide 
being formed as an intermediate product : (C 2 H 5 0) 6 A1 2 = A1 2 3 + 3(C 2 H 5 ) 2 0. In some 
cases this general method can be advantageously employed industrially. 

When the ethers are prepared from the alkoxides in alcoholic solution there should not 
be an excess of water (more than 50 per cent.) present, otherwise the alkoxide decomposes 
into alcohol and alkali hydroxide and no ether is formed. 

Also when sulphuric acid (or HC1) is used in the preparation, an equilibrium sets in 
between the reacting products intermediate and final this equilibrium being regulated 
by the mass law, so that a certain yield cannot be exceeded except by eliminating some 
of the new products formed (e.g. by gradually distilling the ether ; see later) : 



(a) C 2 H 5 .OH + H 2 S0 4 = C2H 5 .S0 4 H + H 2 O. 

Ethylsulphuric acid. 

(b) C 2 H 5 .S0 4 H + C 2 H 5 -OH = H 2 S0 4 + C 2 H 5 .O.C 2 H 6 . 

The sulphuric acid is regenerated and can transform fresh alcohol into ether ; theoreti- 
cally, then, the initial quantity of sulphuric acid should be sufficient to transform an 
infinite quantity of alcohol into ether, but in practice it is necessary to add a small quantity 
of the acid each time, as some of it is used up in the formation of sulphur dioxide, ethylene, 
and sulphonated products. The process is thus not practically continuous in the strict 
sense of the term, since in the phase (a) water is formed, and this cannot all be eliminated 
by distillation, but after a time accumulates in such quantity as to establish an equilibrium 
between the formation of ether and the decomposition of ethylsulphuric acid, alcohol and 
sulphuric acid thus being regenerated. 

The ethers are very stable and scarcely react in the cold with alkalis, 
dilute acids, sodium or phosphorus pentachloride. When superheated with 
water and a little mineral acid, ether is converted back into alcohol : 

C 2 H 5 -0-C 2 H 5 + H 2 S0 4 = C a H 5 -OH + C,H 6 -S0 4 H 

and the same change occurs on saturating ether at with gaseous hydrogen 
iodide : 

(C 2 H 5 ) 2 + HI - C 2 H 5 -OH + C 2 H 5 I, 

the hydrogen iodide subsequently converting he alcohol also into gthyl iodide ; 



192 ORGANIC CHEMISTRY 

when mixed ethers are taken, the iodine unites preferably with the radicle 
containing the lesser amount of carbon. PC1 5 also decomposes the ethers on 
heating : 

(C 2 H 5 ) 2 + PC1 5 = POC1 3 + 2C 2 H 5 C1. 

The halogens give substitution products just as they do with the hydro- 
carbons, but nitric acid gives oxidation products. 

In the ethers are reproduced all the cases of isomerism presented by the 
alkyl groups from which they are derived, there being consequently numerous 
cases of metamerism (see p. 17), e.g. methyl amyl ether, CH 3 -OC 5 H U , is 
metameric with ethyl butyl ether, C 2 H 5 -0-C 4 H 9 , and also with dipropyl 
ether, C 3 H 7 - 0- C 3 H 7 , all these having the empirical formula C 6 H 14 0. 

METHYL ETHER, CH 3 -O-CH 3 (Methoxymethane), is a gas, but liquefies at 23, 
and then has a sp. gr. 1 -617 ; it resembles ethyl ether. One volume of water dissolves 37 vols. 
of the gas, and 1 vol. of sulphuric acid 600 vols. of it. 

ETHYL ETHER, C 4 H 10 O (Ethokyethane), C 2 H 5 -0-C 2 H 5 . This was pre- 
pared for the first time in the sixteenth century by Valerius Cordus from spirit 
of wine. It was formerly thought to contain sulphur, and was therefore given 
the name sulphuric ether, still in use. Its true composition was established by 
Saussure and by Gay-Lussac (1807 and 1815) and the constitution was enun- 
ciated by Laurent and Gerhardt and confirmed experimentally by Williamson. 
It was thought for a long time that the sulphuric acid employed in the manu- 
facture of ether possessed the sole function of fixing and subtracting water 
from the alcohol. Since, however, it was found that water formed in the 
reaction always distilled with the ether, this hypothesis became invalid, and 
Berzelius and Mitscherlich attributed the reaction of etherification to the 
catalytic action of the sulphuric acid. 

Later on Liebig maintained that the ether is formed by the direct decom- 
position of the intermediate product (ethylsulphuric acid) with separation, 
in the hot, of S0 3 . Graham, however, succeeded in showing that ethyl- 
sulphuric acid, when heated alone at 140, does not give ether, but that the 
latter is formed in presence of alcohol. In 1851 Williamson gave the true 
explanation of the process by dividing the reaction into two phases (a and b, see 
preceding page) ; the secondary products, explaining the loss of sulphuric acid 
(see above], were discovered later. 

Etherification takes place also if the sulphuric acid is replaced by phos- 
phoric, arsenic, boric, or hydrochloric acid. 

Sulphur dioxide, which is formed and lost in this process, is not produced 
if the sulphuric acid is replaced by an aromatic sulphonic acid, for instance, 
C 6 H 5 -S0 3 H, or the corresponding chloride, C 6 H 6 -S0 2 C1 (Kraft and Ross, 
Ger. Pat. 691,115), the temperature of the reaction being then slightly above 
100: 

(a) C 2 H 5 -OH + C 6 H 5 -S0 3 H = H 2 + C 6 H 5 -S0 2 -OC 2 H 5 . 

(b) C 2 H 5 -OH + C 6 H 5 .S0 2 -OC 2 H 5 = (C 2 H 5 ) 2 + C 6 H 5 -S0 3 H. 

J. W. Harris's process (U.S. Pat. 711,656) may also have an industrial 
future ; in this, acetylene and hydrogen give ethylene which, with H 2 S0 4 , 
forms ethylsulphuric acid, the latter then forming ether under the action of 
water. 

Good results are also given by the use of methionic acid, CH 2 (S0 3 H) 2 , 
proposed by Schroeter and Sondag in 1908 ; with this acid all the higher ethers 
can be prepared and 10 per cent, of the acid (on the weight of alcohol) is sufficient 
to give a continuous distillation of ether. 

Senderens transforms alcohol vapour quantitatively into ether by passing 
it over calcined, precipitated alumina heated exactly to 260 (see p. 191). 



PROPERTIES OF ETHER 



193 



PROPERTIES. Ether is a colourless, very mobile liquid boiling at 34-9, 
solidifying at -129, and melting at -113 ; it has the sp. gr. 0-7196 at 15. 
At 120 its vapour pressure is 10 atmos. On evaporation, it produces intense 
cold. It inflames very readily, but is not inflammable when mixed with 
35 to 50 per cent, of carbon tetrachloride. With air it forms explosive mixtures 
(p. 33). It is obtained anhydrous by distilling over a little sodium. 

J. Meunier (1907) has found that mixtures of ether vapour and air become 
inflammable and explosive when they contain from 75 to 200 mgrms. of ether 
per litre of air. 

As ether vapour is much heavier than air (mol. wt. 74), it tends to collect 
in a dense, invisible layer on the floor or bench and may cause fire or explosion. 
It is soluble in concentrated hydrochloric acid. 

Water dissolves 6-5 per cent, of ether at 19, and ether dissolves about 
1-25 per cent, of water at 20. Aqueous 
ether can be recognised by the turbidity pro- 
duced on shaking it with a small quantity of 
carbon disulphide. It is moderately soluble 
in concentrated sulphuric acid (1 vol. H 2 S0 4 
dissolves 1-67 vol. of ether). It is an excellent 
solvent for many organic substances. It 
combines with certain inorganic substances 
(chloride of tin, aluminium, phosphorus, 
antimony, &c.) as ether of crystallisation. 

The action of light on ether produces small 
quantities of hydrogen peroxide, acetaldehyde, 
acetic acid, and vinyl alcohol. In contact with 
platinum black, ether ignites. When poured 
into a cylinder of chlorine it explodes and 
forms hydrogen chloride, whilst in the dark 
the slow reaction yields perchloroether. Ether 
is an anaesthetic and was used as such before 
chloroform ; it is again coming into use at 
the present time, as it is not very dangerous, 
although it produces certain disturbing effects, 
for example, in the lungs. For this purpose 
it must be used in a highly purified con- 
dition. 

When mixed with liquid carbon dioxide, 
it lowers the temperature to 79-5 below zero 
giving acetaldehyde. 

INDUSTRIAL PREPARATION OF ETHER. Use is generally made of the con- 
tinuous process, the apparatus employed being that of Boullay or of Barbet ; 9 parts of 
concentrated sulphuric acid of 66 Be. (free from nitric and nitrosylsulphuric acids, 
which would attack the copper of the apparatus) and 5 parts of 90 per cent, alcohol free 
from fusel oil are taken. Heckmann's apparatus for working on a small scale is shown in 
Fig. 176 : A is the alcohol reservoir which feeds the alcohol regularly through the tap, a, 
and the glass vessel, b, to the still, B, containing the sulphuric acid ; indirect steam under 
pressure is supplied to the coil, e. The ether continually distilling over is condensed in 
the coil, C, immersed in cold water. 

The Barbet apparatus (Fig. 177) is used for the production of large quantities of ether, 
and consists of a vertical cylindrical boiler, A, inside which is the steam coil, C. The alcohol 
is introduced by the central tube, H, whilst another tube is used at the beginning for the 
acid and still another, of greater width, allows the ether vapour to escape to the saturator 
and the condenser. The boiler and the coils are of copper or of iron lined with lead. 

First of all, 3500 kilos of sulphuric acid (66 Be.) and 1500 kilos of 95 per cent, 
alcohol are introduced and are heated to 130 by means of the steam-coil ; as the ether 
II 13 




FIG. 176. 



It decomposes at above 500 C 



194 



ORGANIC CHEMISTRY 



distils alcohol is automatically added in a continuous stream. To remove the acid products 
carried over by the ether, use is made of a saturator (Fig. 178), which contains a number of 
plates like a rectifying column and down which flows a solution of soda. 

The crude ether, distilled and condensed in the refrigerating coil, contains a little alcohol, 
water, and other impurities ; to dry and purify it, it is redistilled over calcium chloride 
and then rectified in a column apparatus. Distillation over sodium wire yields a very pure 
product. 

The premises where the distilling apparatus is situated are usually separated by thick 
walls from the condenser, in order to avoid the danger of fire and explosion. Some premises 
are fitted with channels and draught-apertures for rapidly dispersing any vapour which 
may find its way into the air. The distilled vapour is condensed in closed apparatus, 
the only outlet to which is a tube opening on the roof. 

If the temperature of etherification exceeds 140, the yield diminishes, as a considerable 

quantity of ethylene is then 
formed : C 2 H 5 OH = H 2 + C 2 H 4 . 
On the other hand, if the tem- 
perature falls below 130, a large 
amount of alcohol distils without 
reacting. 

The alcohol for making ether 
is denatured so as to be exempt 
from taxation, and in Germany 
animal oil (Dippel's) is added, 
this being then fixed and decom- 
posed by the sulphuric acid. In 
Italy the alcohol is denatured with 
sulphuric acid. 

D. Annaratone (Ger. Pat. 
231,395, 1909) obtains increased 
yields of ether by passing alcohol 
vapour, superheated to 130, into 




FIG. 177. 




p IG 



a column filled with pebbles, among which the sulphuric acid is circulated or sprayed ; 
for 100 kilos of ether only 180 kilos of steam are required for heating instead of 700 
kilos used in the old process. 

USES AND PRODUCTION. The amount of ether manufactured in 
Germany in 1902 was about 2000 tons, without counting that now made in 
large quantities for the production of artificial silk by the Chardonnet-Lehner 
process. 

In Italy large amounts of ether were manufactured before the artificial 
silk factories were closed ; it is protected by a Customs duty of 3 12s. The 
importation into Italy has fallen to 25 quintals. In 1907, Gulinelli's distillery 
(Ferrara) alone produced 3588 quintals of ether. Owing to the crisis in the 
Italian artificial silk industry, the production had fallen considerably in 1910. 

Ether exempt from duty is sold in Germany at 4 per quintal if its sp. gr. 
is 0-722, whilst the price of the pharmacopcsial product, sp. gr. 0-720, is 4 10s. 
Taxed ether, distilled over sodium and chemically pure, costs 4s. per kilo. In 
1909, ether for artificial silk manufacture cost 2 11s. per quintal in Belgium and 
2 14s. in Austria. 

Ether is used in small quantity as an anaesthetic, and in large quantities 
in the manufacture of collodion and artificial silk, and also as a solvent for 
numerous organic compounds in dye and perfume factories. In Ireland it 
is drunk as a liqueur a refined form of alcoholism. 

Various chlorinated derivatives of ether are known. 

Also Ethyl Peroxide, C 2 H 5 -O-O-C 2 H 5 , is prepared by introducing ethyl groups into 
hydrogen peroxide by means of ethyl sulphate ; it is a liquid, b.pt. 65, soluble in water 
and very readily inflammable, but is moderately stable towards chemical reagents. 

Jn 1901 Baeyer prepared also the Hydrate of Ethyl Peroxide, C 2 H 5 O OH, as a colourless 



MERCAPTANS AND SULPHIDES 195 

liquid, which possesses strong oxidising properties, dissolves in water, boils at 95, and 
forms barium and other salts. 

TESTS FOR ETHER. Ether containing water or alcohol has a specific gravity of 
0-720-0-722-0-725 or even 0-733. When 20 c.c. of ether are shaken with 5 c.c. of water, 
the latter should not exhibit an acid reaction. The presence of ozone or hydrogen peroxide 
in ether is revealed by potassium iodide solution, which turns brown within an hour in the 
dark. If water is present, the ether imparts a green or blue colour to ignited white copper 
sulphate. 

In a mixture of alcohol and ether, Fleischer and Frank (1907) determine the proportions 
of the two components by pouring 10 c.c. into a graduated cylinder containing 5 c.c. of 
benzene and 5 c.c. of water. After shaking, the increase in volume of the water gives 
the alcohol and the increase in volume of the benzene shows the quantity of ether. 



II. THIO-ALOCOHLS AND THIO-ETHERS 

These have the same constitution as the alcohols and ethers, excepting that 
the oxygen is replaced by sulphur. They are very volatile and inflammable 
liquids, almost insoluble in water and having repulsive garlic-like odours ; 
in the higher members, however, the odour diminishes and the solubility in 
water vanishes, although they continue to be soluble in alcohol or ether. 

(a) THIO-ALCOHOLS (or Mercaptans or Thiols or Alkyl Sulphydrates), 
C W H 2W+1 SH, have lower boiling-points than the corresponding alcohols. They 
are feebly acid in character and form salts called Mercaptides, e.g. with mercuric 
oxide. They are soluble in concentrated alkali solutions. They may be 
regarded as hydrogen sulphide in which one atom of hydrogen is replaced by an 
alkyl radicle, e.g. ethanthiol or ordinary Mercaptan, C 2 H 5 SH. As acids they 
are monobasic, and salts are formed with metallic sodium or potassium ; the 
lead salts are yellow and are obtained by the action of lead acetate in alcoholic 
solution. Nitric acid transforms the mercaptans into alkylsulphonic acids : 
C 2 H 5 SH + 30 = C 2 H 5 -S0 3 H. 

With iodine, the salts of sodium, &c., give disulphides : 

2C 2 H 5 SNa + I 2 = 2NaI + (C 2 H S ) 2 S 2 , 

which, with hydrogen, give mercaptans, and with nitric acid disulphoxides, 
(C 2 H 5 ) 2 S 2 2 ; concentrated sulphuric acid gives disulphides and is itself reduced 
to sulphur dioxide. 

(6) THIO-ETHERS (or Alkyl Sulphides), (C w H 2n+1 ) 2 S, are neutral, 
readily volatile liquids, and afford a good illustration of the variability of the 
valency of sulphur (di- to hexa-valent). 

They may be regarded as derived from hydrogen sulphide by replacement 
of the two hydrogen atoms by alkyl groups. With salts they form double 
compounds, e.g. ethyl sulphide with mercuric chloride gives (C 2 H 5 ) 2 S, HgCl 2 . 
They combine with halogens, giving, for instance, (C 2 H 5 ) 2 SBr 2 , whilst when 
treated with dilute nitric acid they fix an atom of oxygen, yielding, e.g. 
(C 2 H 5 ) 2 SO, ethyl sulphoxide ; with more energetic oxidising agents, a further 
oxygen atom is taken up with formation of sulphones, e.g. Diethylsulphone, 
(C 2 H 5 ) 2 S0 2 . With hydrogen, the sulphoxides give sulphides, but the sul- 
phides are not reduced. They combine with alkyl haloids, forming sulphonium 
compounds, e.g. ethyl iodide and ethyl sulphide give Triethylsulphonium 
Iodide, (C 2 H 5 ) 3 SI, which reacts like metallic iodides with silver hydroxide, 
yielding Triethylsulphonium Hydroxide, (C 2 H 5 ) 3 S-OH. 

METHODS OF FORMATION. They are obtained : (1) by heating alkyl haloids 
or salts of alkylsulphuric acid with an alcoholic or aqueous solution of potassium sul- 
phide or hydrosulphidc : C 2 H 5 Br + KSH = KBr + C 2 H 5 SH : 2C 2 H 5 Br + K 2 S = 2KBr + 
(C 2 H 5 ) 2 S; 2C 2 H 5 -S0 4 K + KS = 2.K,SO 4 + (C 2 H 5 ) 2 S. 



(2) By the action of phosphorus pentasulphide, P 2 S 5 , on ethers. Mixed sulphides can 
also be obtained by these and various other methods. 

METHYL HYDROSULPHIDE (Methanthiol) , CH 3 -SH, is found among the 
gases from the anaerobic decomposition of proteins (for instance, in the intestines 
of animals). It is a nauseous liquid, lighter than water and boiling at 6. 

METHYL SULPHIDE, (CH 3 ) 2 S, is a liquid, b.pt. 37, having a disagreeable 
ethereal odour. 

ETHYL HYDROSULPHIDE (Ethanthiol, Ethylmercaptan, or Mercaptan), 
C 2 H 5 -SH, is a liquid, b.pt. 36, having a repulsive odour and is used for the preparation 
of sulphonal. With sodium ethoxide in alcoholic solution it gives Sodium Mercaptide, 
C 2 H 5 SNa, in white crystals ; Mercuric Mercaptide, (C 2 H 5 S) 2 Hg, has also been obtained. 

ETHYL SULPHIDE, (C 2 H 5 ) 2 S, is a liquid, b.pt. 92, insoluble in water, and forms 
a crystalline bromide (C 2 H 5 ) 2 SBr 2 . 

ETHYL DISULPHIDE (Ethanodithioethane), (C 2 H 5 ) 2 S 2 , boils at 151, and is 
obtained by the action of iodine on mercaptan. 

ETHYL SULPHOXIDE (Ethanosulphoxyethane), (C 2 H 5 ) 2 SO, is a dense liquid, 
soluble in water, and readily reducible. 

ETHYLSULPHONE (Ethanosulphonethane, Diethylsulphone), (C 2 H 5 ) 2 SO 2 , boils 
unchanged and does not undergo reduction. 

TRIMETHYLSULPHONIUM IODIDE, (CH 8 ) 3 SI, obtained from sulphur and 
methyl iodide, forms white crystals soluble in water and with silver hydroxide gives the 
Hydroxide (CH 3 ) 3 SOH, which is an energetic base and displaces ammonia from its salts. 

III. ETHERS OF ALCOHOLS WITH INORGANIC ACIDS 

Ethers formed from an alcohol residue and an acid residue are termed 
Compound Ethers or Esters. We shall here describe those derived from mineral 
acids and shall consider organic acid esters more in detail when the acids 
themselves have been studied. The esters may be regarded as derived either 
from acids by the replacement of the acid hydrogen by an alkyl residue, as 
with the salts, or from alcohols by replacing the hydroxylic hydrogen by an 

acid radicle : TT\T/-A -ir-\*r\ 

HN0 3 . . . KN0 3 .. . C 2 H 5 -N0 3 

or C 2 H 6 -OH . . . C 2 H 5 -0(N0 2 ) . . . C 2 H 5 -0(S0 3 H). 

Monobasic acids form only one class of esters, viz. normal esters. 

Dibasic acids form two series of esters, normal and acid : e.g. C 2 H 5 HS0 4 , 
acid esters, and (C2H 5 ) 2 S0 4 , normal ester. 

Tribasic acids give three kinds of esters with constitutions analogous to 
those of the salts. 

The Normal Esters are neutral liquids of agreeable odour, moderately 
volatile and insoluble in water. 

The Acid Esters have acid reactions, are less stable, odourless, soluble in 
water, and volatile without decomposition. 

In general, these esters are decomposed by alkali or water at a high tempera- 
ture (150 to 180), the components being regenerated ; this change is known 
as Saponification : C 2 H 5 N0 3 + KOH = C 2 H 5 -OH + KN0 3 . 

FORMATION. (1) They are usually formed by the interaction of the 
components (absolute alcohol + acid), the water which gradually forms being 
fixed and the resulting ester distilled. With some acids, the corresponding 
salts in presence of concentrated sulphuric acid- at 100 to 130 are taken, 
so that the acid is obtained in the nascent state and the ester driven off as it is 
formed. They are more readily obtainable by saturating the mixture of 
alcohol and salt with gaseous hydrogen chloride. 

(2) From the silver salt of the acid and alkyl iodide : 

Ag 2 S0 4 + 2C 2 H 5 I = 2AgI + S0 4 (C 2 H 5 ) 2 . 



INORGANIC ESTERS 197 

(3) From the alcohol or alkoxide with the chloride of the acid : 

SOC1 2 + 2C 2 H 5 OH = 2HC1 + SO(OC a H 5 ) 2 ; and 
POC1 3 + 3C 2 H 5 ONa = 3NaCl + PO(OC 2 H 5 ) 3 (ethyl phosphate) . 

(4) By passing the vapours of the acid and alcohol together over a catalyst 
as much as 50 per cent, of the ester is obtained. 

1. ESTERS OF SULPHURIC ACID AND ALKYLSULPHURIC ACIDS. These 
are generally prepared from fuming sulphuric acid and alcohol, or from silver sulphate 
and alkyl iodide or from alcohol and sulphuryl chloride, 

S0 2 C1 2 + 2C 2 H 5 OH = 2HC1 + S0 2 (C 2 H 5 O) 2 ; 

acid esters (alkylsulphuric acids) also exist. Tertiary alcohols do not form these esters. 

Ethyl Sulphate, (C 2 H 5 ) 2 S0 4 , is an oily liquid with an odour of mint and a pro- 
nounced acid character ; it boils at 208 and is easily saponified, even by boiling with 
water alone. It is formed by heating ethylsulphuric acid : 

2C 2 H 5 S0 4 H = S0 4 H 2 + S0 4 (C 2 H 5 ) 2 . 

Ethylsulphuric Acid, C 2 H 5 SO 4 H = (C 2 H 5 O-SO 3 H), is formed as an initial product 
in the manufacture of ether (p. 192). It is soluble in water and is distinguished from 
sulphuric acid by the solubility of its calcium, strontium, barium, and lead salts. It 
gives well crystallised salts, the potassium salt being largely used for preparing ethyl 
derivatives, e.g. when it is dry-distilled with potassium bromide : 

KBr + C 2 H 6 SO 4 K = S0 4 K 2 + C 2 H 5 Br. 

2. DERIVATIVES OF SULPHUROUS ACID: (a) Sulphurous Esters; (b) Sul- 
phorric Acids. 

(a) Ethyl Sulphite, SO 3 (C 2 H 5 ) 2 , and ethylsulphurous acid, C 2 H 5 SO 3 H. The latter 
is known also in the form of salts and both are readily saponified, since the sulphur is not 
directly uru'ted with carbon : CH 3 CH 2 SO 2 H. . 

(b) Ethylsulphonic Acid, C 2 H 5 -SO 3 H, is obtained by the reaction 

C 2 H 5 I + SO 3 Na 2 = Nal + C 2 H 5 S0 3 Na ; 
or by oxidising the thioalcohols : C 2 H 5 SH + 3 = C 2 H 5 S0 3 H ; or thus : 

2C 2 H 5 I + Ag 2 S0 3 = 2AgI + (C 2 H 5 ) 2 S0 3 (ethyl ethylsulphonate). 

Sulphonic acid compounds are not saponifiable ; diethylsulphonic acid is saponifiable to 
the extent of one-half, since in the sulphonic acids the sulphur is united with carbon : 
CH 3 CH 2 S0 2 OH ; the presence of hydroxyl is shown by the fact that with PC1 5 it 
forms C 2 H 5 S0 2 C1, which with hydrogen gives ethylsulphinic acid, C 2 H 6 SHO 2 , the salts 
of the latter reacting with alkyl haloids to form sulphones. 

3. ESTERS OF NITRIC ACID. These are explosive if heated rapidly and undergo 
saponification when boiled with an alkali. Tin and hydrochloric acid reduce them, giving 
Hydroxylamine, NH 2 OH, the nitrogen being separated from the radicle as in saponification; 

Ethyl Nitrate : C 2 H 5 O-NO 2 , is a liquid boiling at 86. 

4. ESTERS OF NITROUS ACID. These are easily obtained by passing nitrogen 
trioxide (N 2 O 3 ) into the alcohols, or by treating the latter with alkali nitrites and sulphuric 
acid. They are reduced by nascent hydrogen, giving alcohol and ammonia. 

Ethyl Nitrite, C 2 H 5 O-NO, was at one time called-m'Jn'c ether. Dissolved in alcohol, it 
bears the name spiritus cetheris nitrosi, and is used to modify the taste of various substances. 
It is also used for preparing diazo -compounds. 

5. NITRO-DERIVATIVES OF THE HYDROCARBONS. These are isomeric 
with nitrous esters but they boil at higher temperatures than the latter and are distinguished 
from them by being non-saponifiable and by giving organic amino-compounds on reduction, 
as long as the nitrogen is not severed from the organic radical : 

CH 3 .NO 2 (nitromethane).+ 3H 2 = 2H 2 O + CH 3 -NH 2 . 
They are formed by treating alkyl iodides with silver nitrite : 

CH 3 I + AgNO 2 = Agl + CH 3 -N0 2 ; 
with the higher members of the series, the nitrous esters are formed at the same time 



198 ORGANIC CHEMISTRY 

and may be separated by distillation. Of the various methods of formation, mention may 
be made of that based on the action of dilute nitric acid, in the hot and under pressure, on 
the paraffins : 

C 6 H 14 + HN0 3 = C 6 H 13 .N0 2 + H 2 O. 

Hexane Nitrohexane 

Concentrated nitric acid does not give nitro -compounds with the paraffins, but with 
aromatic hydrocarbons it reacts readily. 

The difference in constitution between nitro-derivatives, e.g. H 3 C-N0 2 , and nitrous 
esters, e.g. H 3 C-0-N : O, explains their different relations as regards saponification. 

This also confirms the hypothetical constitution of nitrous acid, O : N OH. The 
hydrogen of the carbon atom united to nitrogen can be partially substituted by metals or 
bromine, since it has acquired acid characters for instance, NaCH 2 N0 2 but the acidify- 
ing influence of the nitro -group is not extended to the hydrogens of the other carbon atoms. 

These nitroparaffins react with nitrous acid differently according as they are primary, 
secondary, or tertiary : 

A Jff.OH 

(a) Nitroethane, CH 3 - Of + NO 2 H = H 2 O + CH 3 - Of i.e. ethyl- 

X N0 2 \NO 2 

nitric acid, salts of which are red. 

CH 3 ,IL CH 3X N = O 

(6) Secondary Nitropropane, \OQ + N0 2 H = H 2 O + )C<f 

CH 3 / \N0 2 CH 3 / \N0 2 

propylpseudonitrole, which forms blue salts. 

(c) Tertiary derivatives give no reaction. 

These reactions serve well to distinguish primary, secondary, and tertiary alcohols. 

Nitroethane may be used in the manufacture of explosives to lower the freezing-point of 
nitroglycerine. 

CHLOROPICRIN, CC1 3 -N0 2 , boils at 112, and is formed by the simultaneous action 
of nitric acid and chlorine on various organic compounds. 

NITROFORM, CH(NO 2 ) 3 , and TETRANITROMETHANE,C(N0 2 ) 4 , are crystallisable 
substances which boil unchanged. R. Schenck (Ger. Pat. 211,198, 1908) has prepared 
tetranitromethane in various ways. 

6. Various esters of hyponitrous, phosphoric, boric, silicic, &c., acids are known. 

DERIVATIVES OF HYDROCYANIC ACID 
A. NITRILES. B. ISONITRILES 

These compounds are formed by the substitution of the hydrogen of hydrocyanic acid 
by an alkyl radical, but they are not true esters, as they do not give the acid and alcohol 
again on hydrolysis. 

A. NITRILES (or Alkyl Cyanides), are either liquid or solid, and have a 
pleasant, faintly garlic-like, ethereal odour. They are lighter than water, in 
which the first terms are soluble without undergoing change. They boil at 
about the same temperatures as the corresponding alcohols. 

PREPARATION. 1. They are obtained by distilling a potassium alkyl- 
sulphate with potassium cyanide or with anhydrous potassium ferrocyanide, 
or by heating the cyanide at 180 with methyl iodide : 

CH 3 I + KCN = KI + CHg-CN (methyl cyanide or acetonitrile). 

2. Distillation of ammonium salts of monobasic acids yields amido- 
compounds which, with a dehydrating agent (P 2 5 , P 2 S 5 or PC1 5 ), give nitriles : 

(a) CH 3 -COOH + NH 3 = H 2 + CH 3 -CO-NH 2 ; 

Acetic acid Acetamide 

(6) CH 5 CO-NH 2 - H 2 = CH 3 -CN. 

Acetonitrile or 
Methyl cyanide 



NITRILES AND ISONIT RILES 199 

3. The higher nitriles are formed from the acid-amides containing one 
more carbon atom or from the primary amine containing the same number of 
carbon atoms, by treatment with sodium hydroxide and bromine ; or from the 
aldehydes which, with hydrocyanic acid, give the nitriles of higher acids, the 
so-called cyanohydrins or hydroxynitriles, liquid compounds easily saponified 
with regeneration of the aldehyde : 



+Q 

CH 3 Of + HCN = CH 3 CH<( 

X H X CN 

Acetaldehyde Ethylidenecyanohydrin 

PROPERTIES. When boiled with alkali or acid, or treated with 
superheated steam, nitriles give ammonia and an acid, from which products 
they can also be formed : 

(a) CH 3 CN + H 2 = CH 3 -CO-NH 2 (acetamide) ; 
(6) CH 3 -CO-NH 2 + H 2 = CH 3 -CO-OH + NH 3 . 

This reaction is of importance for the synthesis of organic acids since, 
starting from a given alcohol and transforming it into iodide and then nitrile, 
an acid of the saturated series containing an extra carbon atom is obtained. 

If the cyanide is treated with hydrogen sulphide instead of water, 
thioacetamide, CH 3 -CS-NH 2 , is obtained. With hydrochloric acid, the 
nitriles form chloramides or chlorimides, whilst with ammoniacal bases they 
give amidines (see later). Nascent hydrogen converts, them into amines : 
CH 3 -CN + 2H 2 = CH 3 -CH 2 -NH 2 (ethylamine). By potassium or gaseous 
hydrogen chloride the nitriles are polymerised. 

ACETONITRILE (or Methyl Cyanide), CH 3 -CN, is found among the 
products of distillation of beetroot molasses and of tar. It is soluble in 
water and boils at 82. 

B. ISONITRILES (Isocyanides or Carbylamines) are colourless liquids 
which have a faint alkaline reaction and boil at rather lower temperatures than 
the corresponding nitriles. They are insoluble in water but dissolve in alcohol 
or ether. They have repellent odours and are poisonous. They are obtained 
by the interaction of alkyl iodides with silver cyanide (whilst with potassium 
cyanide the nitriles are obtained) : 

C 2 H 5 I + AgCN = Agl + C 2 H 5 -NC ; 

they are also formed by treating the primary amines with chloroform and 
alcoholic potash (see p. 100 ; also later under Amines). 

Although they are stable towards alkalis, the isonitriles are readily 
decomposed by water giving formic acid and the corresponding amino-base 
containing one carbon atom less than the isonitrile : 

CH 3 -NC + 2H 2 = H-COOH + CH 3 -NH 2 . 

From the nitriles they are distinguished also by the different additive 
compounds which they form with halogens, hydrogen chloride, hydrogen 
sulphide, &c. At high temperature certain isonitriles change into nitriles. 

CONSTITUTION OF THE NITRILES AND ISONITRILES. The nitriles have the 
carbon atom of the cyanogen group attached to the alkyl radicle and when they are hydro - 
lysed only the nitrogen is removed as ammonia. Acetonitrile would hence have the 
constitution, CH 3 C^N. 

The isonitriles, on the other hand, readily form amino -bases with loss of an atom of 
carbon that of the cyanogen group the nitrogen remaining with the radicle. Methyl - 
isocyanide or methylcarbylamine would hence have the formula CH 3 N==C. 



200 ORGANIC CHEMISTRY 


IV. NITROGENATED BASIC ALKYL COMPOUNDS (AMINES) 

If one or more of the hydrogen atoms of the ammonia molecule is replaced 
by one or more alkyl radicles, substances called Amines are formed ; these 
have a basic character, which is in some cases more marked than that of 
ammonia itself (in the dissociation of compounds of the ammonia type, free 
anions, OH', are formed). To ammonia they present other chemical analogies. 
They have disagreeable ammoniacal odours ; with mineral acids they form 
white, crystalline, deliquescent salts which are extremely soluble in water 
and have a basic nature, the nitrogen then becoming pentavalent ; for the 
first members of the series the electrical conductivity is very high, higher 
indeed than that of ammonia, since N/100 solutions are almost completely 
dissociated. 

Like ammonia, they give, with platinum chloride, crystalline platinichlorides, 
e.g. methylamine platinichloride, (NH 2 -CH 3 , HCl) 2 PtCl 4 ; they also form 
double salts with gold chloride, NH 2 -C 2 H 5 , HC1, AuCl 3 . They precipitate 
heavy metals from solutions of their salts, and, in excess, sometimes redissolve 
them. The first terms are gases, after which come unpleasant smelling 
liquids soluble in water. The higher members are odourless and insoluble in, 
and lighter than, water ; they are soluble in alcohol and in ether. 

The ammonia derivatives are deliquescent solids, and in their behaviour 
greatly resemble potassium hydroxide, &c. According as they contain one 
or more alkyl radicals, these bases are called primary or aminic, secondary or 
iminic, tertiary or nitrilic, quaternary or ammoniacal. 

PROCESSES OF FORMATION, (a) By heating an alkyl halogen com- 
pound with ammonia : 

(1) NH 3 + C n H 2+1 I = HI + C w H an+1 NH 2 ; the halogen hydracid formed 
unites with the ammonia and with the amine, converting these partly into the 
corresponding salts ; distillation with potassium hydroxide then gives : 
KI + H 2 + the free base, C M H 2n+1 -NH 2 . The latter, which is partly free 
before treatment with potash, can in its turn react with a second molecule of 
the alkyl halogen compound, giving a secondary amine ; 

(2) C M H 2W+1 -NH 2 + C w H 2n+1 I = (C W H 2W+1 ) 2 NH, HI; the free base, which 
can be liberated by distilling with KOH, reacts with a third molecule of 
the alkyl halogen compound, yielding a tertiary amine ; 

(3) (C M H 2n+1 ) 2 NH + C W H 2W+1 I = (C n H 2w+1 ) 3 N, HI. Finally, the tertiary 
base, which remains free or can be liberated, reacts with a fourth molecule 
of the halogen derivative, giving the salt of the quaternary base ; 

(4) (C n H 2n+1 ) 3 N + C n H 2n+1 I = (C W H 2M+1 ) 4 NI, which is no longer a crystalline 
ammonia base and is not decomposed by potassium hydroxide, being more 
energetic than the latter ; the hydrogen iodide formed unites with the amines 
if such are still present. When heated, the iodide of the quaternary base is 
converted back into the tertiary base and alkyl iodide, whilst with silver 
hydroxide it gives the corresponding solid alkylammonium hydroxide. In 
this general reaction, the four bases are always formed together, although more 
of one or another is obtained according to the nature of the alkyl group, the 
temperature, the duration of the reaction, and the quantity of ammonia present. 

The separation of the bases in this mixture is not easy, and when these are 
present as salts, distillation with potassium hydroxide yields the primary, 
secondary, and tertiary amines, whilst the quaternary ammonium compound 
remains unchanged. The three bases or the corresponding salts are separated 
partly by crystallisation or by fractional distillation, or, better, by means of 
ethyl oxalate, C 2 2 (C 2 H 5 O) 2 , which gives solid or liquid oxamides [e.g. solid 
dimethyloxamide, C 2 2 (NH-CH 3 ) 2 and the ethyl ester of dimethyloxaminic acid, 
C 2 H 2 (OC 2 H 5 )-N(CH 3 ) 2 ]. 



A- M I N E S 201 

Amines can also be prepared by the following reactions : 

(b) By the action of potassium hydroxide on alkyl isocyanates, e.g. ethyl 
isocyanate, C 2 H 5 NCO + 2KOH = K 2 CO 3 + C 2 H 5 -NH 2 ; 

(c) By reducing nitro-compounds, nitrites, oximes, or hydrazones with 
nascent hydrogen. 

PROPERTIES. The amines do not undergo hydrolysis and are resistant 
to the action of acids, alkalis, and, to some extent, oxidising agents. The 
hydrogen combined with the nitrogen of amines can be replaced not only by 
alkyl groups (see above), but also by acid radicals (e.g. by acetyl, CH 3 -CO-) 
and mixed amines with alkyl and acidic groups can also be obtained. A 
characteristic and sensitive reaction of the primary amines is that with chloro- 
form in presence of alkali, which gives rise to the unpleasant-smelling isonitriles : 
CHC1 3 + CH 3 -NH 2 + 3KOH = CH 3 -NC + 3KC1 + 3H 2 0. In alcoholic solu- 
tion the primary and secondary bases form, with carbon disulphide, deriva- 
tives of thiocarbaminic acid, and only when these are derived from the 
primary bases can isothiocyanates be obtained. It is easier to distinguish 
(and separate) primary, secondary, and tertiary amines by their reactions with 
nitrous acid. When a hydrochloric acid solution of the mixture is treated 
with a concentrated solution of sodium nitrite, the primary amine yields the 
corresponding alcohol (soluble in water), with evolution of nitrogen : 

C n H 2n+1 NH 2 + NOOH = H 2 + N 2 + C n H 2M+1 OH. 

The secondary amines give oily nitrosamines, almost insoluble in water : 
(C n H 2W+1 ) 2 NH + NOOH = H 2 + (C n H 2n+1 ) 2 N-NO ; with feeble reducing 
agents, the nitrosamine is transformed into a hydrazine, whilst with more 
energetic reducing agents or with concentrated hydrochloric acid the secondary 
amine is regenerated, showing that the nitrous residue NO is joined to the 
iminic nitrogen and not to the carbon. The tertiary amine does not react with 
nitrous acid and is hence left unchanged in the solution, from which it can be 
obtained by distillation in presence of caustic soda. 

Finally, the three classes of amines can be distinguished by the quantities 
of methyl iodide with which they react to produce the final quaternary base 
(see preceding page), with generation of greater or less quantities of ionisable 
compounds (titratable HI). 

METHYL AMINE, CH 3 -NH 2> is found ready formed in certain plants, e.g. in the dog- 
mercury weed (Mercurialis perennis). It is formed in the distillation of wood and occurs 
in beetroot and bone residues and in herring brine. It is a gas like ammonia and precipitates 
various metallic salts, but, when added in excess, does not dissolve nickel and cobalt 
hydroxides ; it is more highly basic and more soluble in water than ammonia, and has a 
strong odour of ammonia and rotten fish. It becomes liquid at 6 and at 11 has the 
sp. gr. 0-699. With sodium hydroxide and bromine it gives acetamide. Its hydrochloride, 
CH 3 NH 2 ,HC1, is a crystalline, deliquescent substance extremely soluble in alcohol. With 
aluminium sulphate its sulphate forms an alum containing 24H 2 O. 

DIMETHYLAMINE, (CH 3 )NH, is a liquid boiling at + 7, and is formed, together 
with acetic acid, in the distillation of wood. 

TRIMETHYLAMINE, (CH 3 ) 3 N, is a gas which liquefies at +3, and has an intense 
odour of rotten fish. It is found in various plants (Arnica montana, shoots of the pear- 
tree, &c.), and in herring brine. It is formed by the decomposition of betaine during the 
distillation of beetroot molasses (p. 96). 

ETHYLAMINE, C 2 H 5 -NH 2 , is a liquid, b.pt. + 19, and smells strongly of ammonia, 
which it surpasses in basicity. It dissolves very readily in water with generation of heat. 
It dissolves aluminium hydroxide, and to a small extent cupric hydroxide but not ferric 
or cadmium hydroxide. 

DIETHYLAMINE, (C 2 H 5 ) 2 NH, is a liquid, b.pt. 56, and does not dissolve zinc 
hydroxide. 



202 ORGANIC CHEMISTRY 

TRIETHYLAMINE, (C 2 H 5 ) 3 N, is an oily liquid which precipitates metals from their 
salts but does not redissolve the precipitates. It has a strongly alkaline reaction and boils 
at 89. It is extremely soluble in cold water, but above 20 it becomes completely insoluble, 
separating from the water in an oily layer. 

A group of nitrogen compounds which may be considered as formed by the condensation 
of ammonia (hydrazine, azoimide, hydroxylamine, &c.) has been already mentioned in 
vol. i, pp. 327 and 332. The alkyl derivatives of hydroxylamine, NH 2 -OH, are divided 
into two groups : a-alkylhydroxylamines, in which the alkyl replaces the hydroxylic hydrogen 
NH 2 OR, and which hence have an ether character and do not reduce Fehling's solution ; 
and ft-alkylhydroxylamines, in which the alkyl radical replaces an amino -hydrogen and is 
therefore joined to the nitrogen, R NH OH ; these reduce Fehling's solution even in the 
cold and on energetic reduction yield primary amines. 

Also the Alkylhydrazines, RNH NH 2 , R 2 N-NH 2 , &c., unlike amines, reduce Fehling's 
solution in the cold and give characteristic reactions with aldehydes and ketones. 

The Diazo-compounds of the methane series are of slight importance, whilst those of the 
aromatic series are a very important class of compounds ; the former differ from the latter 
in that the characteristic divalent nitrogen group, N=N , has its valencies saturated 
by only one carbon atom. Diazomethane, CH 2 N 2 , which is a yellow, poisonous gas, is 
prepared from hydroxylamine and dichloromethylamine. 

V. PHOSPHINES, ARSINES, AND ALKYL METALLIC COMPOUNDS 

Like ammonia, the hydrogen derivatives of phosphorus, arsenic, antimony, &c., give rise 
to alkyl compounds which have a very feebly basic character and a very unpleasant odour. 

1. PHOSPHINES. These are gases or colourless liquids with repulsive odours. Their 
basic properties and their stability towards water become more marked as the number of 
alkyl groups increases. They are readily oxidisable with nitric acid, the remaining hydrogen 
atoms of the PH 3 being transformed into hydroxyl groups. The quaternary phosphonium 
bases are very strongly basic, and, unlike the corresponding ammonium bases, they lose 
an alkyl group in the form of a saturated hydrocarbon when heated, the residue being a 
trialkylphosphonium oxide. 

C w H 2n+1 PH 2 (C n H 2n+1 ) 2 PH (C M H 2n+1 ) 3 P (C n H 2n+1 ) 4 P-OH 

Primary phosphine Secondary phosphine Tertiary phosphine Tetralkylphosphonium 

hydroxide 

C n H 2n+1 PO(OH) 2 (C n H 2n+1 ) 2 PO. OH (C n H 2n+1 ) 3 PO 

Alkylphosphonic acid Dialkylphosphonic acid Trialkylphosphine oxide 

The primary and secondary phosphines are formed by heating phosphonium iodide 
with alkyl iodides and zinc oxide, whilst the tertiary phosphines and phosphonium deri- 
vatives are obtained from hydrogen phosphide, PH 3 , and alkyl halogen compounds. 

2. ARSINES. Well-known primary and secondary compounds are : methylarsenic 
dichloride, CH 3 AsCl 2 (liquid, b.pt. 135) ; dimethylarsenic chloride, (CH 3 ) 2 AsCl (b.pt. 100) ; 
dimethylarsine, (CH 3 ) 2 AsH (b.pt. 36) ; dimethylarsenic acid or cacodylic acid, (CH 3 ) 2 AsO OH, 
&c. The tertiary arsines are obtained by the action of sodium arsenide, AsNa 3 , on alkyl 
iodides : 

3C 2 H 5 I + AsNa 3 = 3NaI + As(C 2 H 5 ) 3 ; 

they are liquids slightly soluble in water, with which they do not form bases. The 
quaternary arsonium compounds, e.g. (CH 3 ) 4 AsI (tetramethylarsonium iodide), obtained 
from the tertiary arsines and alkyl iodides, are, however, very energetic and are able to 
give, with moist silver oxide, tetramethylarsonium hydroxide. The cacodyl 

[(CH 3 ) 2 As - As(CH 3 ) 2 ] 

compounds were studied by Bunsen (1837-J843), who obtained cacodyl oxide, 

(CH 3 ) 2 As-O.As(CH 3 ) 2 , " 

by distilling arsenic trioxide with potassium acetate (this reaction serves as a delicate test 
for acetates in mixtures) : 

As 2 O 3 + 4CH 3 -COOK = 2C0 2 + 2K 2 C0 3 + [As(CH 3 ) 2 ] 2 0. 
With hydrochloric acid, cacodyl oxide gives cacodyl chloride, (CH 3 ) 2 AsCl. 



ORGANOMETALLIC COMPOUNDS 203 

Many of these cacodyl compounds are liquids which ignite in the air and have nauseating 
odours ; the cacodyl behaves like a true electro- positive element. 

3. Various alkyl derivatives are known of antimony (stibines), boron, silicon, bismuth, 
tin, &c., but these are of little practical importance. 

4. ALKYLMETALLIC (Organometallic) DERIVATIVES. These are 
obtained from various metallic chlorides or from the metals themselves (Zn, 
Hg, Mg, Al, &c.) by the action of halogen derivatives of the hydrocarbons. 
They are generally colourless liquids with low boiling-points, and some of 
them are violently decomposed by water and ignite in the air. Of importance 
for many organic syntheses are the zinc-alkyls (see pp. 32, 96, and 149). 

ZINC METHYL : Zn(CH 3 ) 2 , is a colourless, highly refractive liquid, sp. gr. 
1-39, b.pt. 46, and has an intense, repulsive odour ; it ignites in the air, 
forming zinc oxide, and with water gives methane and zinc hydroxide. It is 
formed in two phases, as follows, and is separated by distillation : 

(a) CH 3 I + Zn = Zn(CH 3 )I (zinc methyl iodide, solid) ; 

(b) 2Zn(CH 3 )I = Znl + Zn(CH 3 ) 2 . 

GRIGN ARD ' S REACTION. Mention has already been made of the use of this reaction 
in synthesising the saturated hydrocarbons (p. 32). One molecule of a monohalogen 
(Br or I) compound, in presence of absolute ether, combines with an atom of magnesium : 
Mg + C 2 H 5 Br = C 2 H 5 MgBr (ethyl magnesium bromide), and with compounds containing 
several carbon atoms there is always formed, as a secondary product, a saturated hydro- 
carbon. The ether probably takes part in the reaction, forming an intermediate product 
C 2 H 5 .Mg.Br[(C 2 H 6 ) 2 0]. 

The latter, and also the alkyl magnesium halogen compounds, when dissolved in ether, 
are highly reactive and form additive compounds with aldehydes, ketones, and even 
esters of mono- and poly-basic carboxylic acids ; with water these additive compounds 
then give the corresponding secondary and tertiary alcohols, the reaction occurring in the 
following two phases (R = alkyl) : 

/0-MgI 
R-CHO + R'Mgl = R-C^-R' -> + H 2 O = I-Mg-OH + R.CH(OH)-R' 

Aldehyde Alkyl mag- H Secondary 

nesium iodide alcohol 

/OMg-Br 

H - COOC 2 H 5 + C 2 H 5 MgBr = C 2 H 5 - C^H -> + C 2 H 5 . MgBr = 

Ethyl formate X OC 2 H 5 

/OMgBr 
Br.Mg.OC 2 H 5 + C 2 H 5 .CH -> + H 2 O = BrMgOH + C 2 H 5 .CH(OH).C 2 H 5 

Diethylcarbinol 



If esters of other monobasic acids are used instead of a formic ester, tertiary alcohols 
are obtained, whilst esters of dibasic acids give dihydric alcohols. Hence, by means of 
the Grignard reaction, the carboxylic oxygen of any acid (starting from the corresponding 
ester) is ultimately replaced by two alkyl residues. Similar behaviour is also shown by acid 
chlorides and anhydrides, which also contain carbonylic oxygen ( CO ). 

With nitriles, Tcetonimides and ketones are obtained : 

yN-Mgl 

R-CN + R'Mgl = R-Cf -* + H 2 O = 

X R' 

IMgOH + R.C ( : NH).R' -> + H 2 = NH 3 + R.CO-R'(ketone). 
Further, with dry CO 2 , alkyl magnesium compounds give organic acids : 

R'Mgl + CO 2 = R'-COOMg-I -v + HX = IMgX + R'-COOH (acid). 

Other most varied organic syntheses have been rendered possible of late years by the 
Grignard reaction. 



204 ORGANIC CHEMISTRY 

VI. ALDEHYDES AND KETONES, C w H 2n O 

The elimination of two atoms of hydrogen by means of an oxidising agent 
(e.g. potassium dichromate and dilute sulphuric acid, or sometimes even the 
oxygen of the air), from a primary or secondary alcohol yields an aldehyde or 
a ketone : R-CH 2 -OH + = H 2 + R-CHO (aldehyde), or 

R-CH(OH)R' + = H 2 + R-CO-R' (ketone). 

The aldehydes have a strong reducing action, as they fix oxygen and 
become converted into acids with the same numbers of carbon atoms, whilst 
the ketones resist oxidising agents, and, if these are very energetic, are 
oxidised to acids containing fewer carbon atoms than the original ketones. 



(a) ALDEHYDES 

The first members of this series are neutral liquids with pronounced and 
often disagreeable odours (formaldehyde is a gas) and are soluble in water, 
whilst the higher ones gradually become solid and insoluble. Their boiling- 
points are much lower than those of the corresponding alcohols. 

The aldehydes are formed when a calcium or barium salt (or even two 
salts) of a monobasic organic acid is dry distilled with calcium or barium 
formate (reducing agent): (R-COO) 2 Ca + (H-COO) 2 Ca = 2CaC0 3 + 2R-CHO. 

They are also obtained on heating with water compounds containing two 
halogen atoms united to the same carbon atom : 

CH 3 -CHC1 2 (ethylidene chloride) + H 2 = 2HC1 + CH 3 -CHO. 
The constitution of the aldehydes can be deduced from their methods of 

7 
formation (e.g. the latter) and the characteristic aldehyde group is OC 

X H 

PROPERTIES. They are substances of considerable and varied reac- 
tivity. With oxidising agents they are transformed into acids, and this re- 
ducing property is readily manifested in their reduction of ammoniacal silver 
nitrate solution (22 per cent, ammonia solution and 10 per cent, of dilute silver 
nitrate diluted with its own volume of 10 per cent, sodium hydroxide solution ; 
or 1 grm. of silver nitrate dissolved in 30 c.c. of water and dilute ammonia 
added as long as no precipitate forms) or of Fehling's solution (the latter, how- 
ever, is not reduced by aldehydes containing as many as 8 or 9 carbon atoms). 
In their turn, the aldehydes are converted back into the primary alcohols 
when reduced with nascent hydrogen ; with PC1 5 , they give ethylidene 
chlorides again. 

Hydrocyanic acid, ammonia, sodium hydrogen sulphite, and sometimes 
alcohol and acetic anhydride (also the alkyl magnesium halogen compounds : 
see above, Grignard's Reaction) form characteristic additive products with the 
aldehydes : 

CH 3 -CHO + 2C 2 H 5 -OH (+ a little HC1) = H 2 + CH 3 -CH(OC 2 H 5 ) 2 (acetal), 

which is an ether of the hypothetical glycol (dihydric alcohol), CH 3 - CH(OH) 2 ; 
the latter, however, does not exist in the free state, since two hydroxyl groups 
cannot remain joined to one and the same carbon atom, excepting in the case of 
chloral hydrate (see later) and a very few other substances. 1 

They combine with sodium and ammonium bisulphites (very concentrated 

1 See Table on opposite page. 



ALDEHYDES 



205 



solutions) forming crystalline bisulphite compounds soluble in water and 
slightly so in alcohol : 

OH 



S0HNa = CH 



/ 

-CO- 



H 



H 



S0 2 Na, 



and these compounds, when heated with dilute acid or with alkali (even 
Na 2 C0 3 ), liberate the aldehyde again. This reaction hence renders possible 
the separation of aldehydes from other substances. 

The aldehydes combine with ammonia forming crystalline aldehyde- 
ammonias soluble in water and slightly so in alcohol but insoluble in ether, 
for example, CH 3 -CH(OH)(NH 2 ), which gives the aldehyde again when heated 
with a dilute acid. But formaldehyde, with ammonia, readily forms poly- 
merised derivatives, e.g. hexamethylenetetramine, (CH 2 ) 6 N 4 . 

With hydrocyanic acid they form cyanohydrins (p. 199). 

An interesting change is the aldol condensation, that is, the condensation 
of 2 mols. of an aldehyde brought about by prolonged heating with dilute 
mineral acids, dilute alkalis, or even aqueous solutions of sodium acetate. 
Possibly a molecule of water is first added to one of the aldehydes : 



CH, 



X 



,0 



H 



H 2 = CH 3 



N 



OH 



this hypothetical hydrate then condensing with another molecule of aldehyde, 
with separation of water and formation of a hydroxyaldehyde (aldol) : 

,0 //O 



CH 3 CHX 



CH C 






H 



= H 2 



CH 8 CH(OH) CH 2 



V H 



(fi-hydroxybutyraldehyde). These aldols in their turn readily lose a molecule 
of water, forming an unsaturated aldehyde, which can also be obtained directly 
(aldehyde condensation) by heating the original aldehyde with a dehydrating 
agent such as zinc chloride : 



CH,-C 



/ 



CH-C 










H 



H 



=H 2 



CH,-CH:CH-C 







H 



DERIVATIVES OP ACETALS 



Name 


formula 


Boiling-point 


Specific gravity 


ALKYL DERIVATIVES 








Mcthylal 


CH 2 (OCH a ) 2 


41-3 -41-7 (749-8 mm.) 


0-862 (18) 


Diethylmethylal . 


CH 2 (OC 2 H 6 ) 2 


87 


0-834 (20) 


Dipropylmethylal 


CH 2 (OC,H,) 2 


136 


0-834 (20) 


Diisopropylmethylal 


CH 2 (OC a H,) 2 


118 


0-831 (20) 


Diisobutylmethylal 


CH 2 (OC 4 H 9 ) 2 


164 


0-824 (20) 


Di i soamylmcthylal 


CH 2 (OC 5 H n ; 2 + H 2 O 


206 


0-835 (20) 


Dihexylmethylal 


CH 2 (OC,H 1S ) 2 


174-175 


0-822 (15) 


Dioctylacetal 


CH 8 -CH(OC,H 17 ) 2 


289 


0-848 (15) 


Dimethylacetal 


CH a -CH(OCH 3 )j 


63 


0-865 (22) 


Diethylacetal 


CH 3 -CH(OC 2 H 5 ) 2 


102-9 


0-831 (20) 


Dipropylacetal 


CH 8 -CH(OC,H,) 2 


147 


0-825 (22) 


Diisobutylacetal 


CH 3 -CH(OC 4 H ! ,) a 


170 


0-816 (22) 


Di isoamylacetal 


CHa-C^OCjHnJj 


211 


0-835 (15) 


ACID DERIVAT VES 








Methylencdiacetate 


CH 2 (0-CO-CH a ) 2 


170 





Ethylencdiacetate 


CH 3 -CH(O-CO-CH 3 ) 2 


169 


1-073 (15) 


Ethyleneclipropionate 


CH3-CH(O-CO-C 2 H 5 ) 2 


192 


1-020 (15) 


Ethylencdibutyratc 


CH 3 -CH(O-CO-C 3 H,) 2 


215 


0-985 (15) 


Ethylenediisovalerate 


CH a -CH(O-CO-C 1 H,) 2 


225 


0-947 (15) 



206 ORGANIC CHEMISTRY 

The aldehydes, especially form-, acet-, and prop-aldehydes, &c., exhibit a 
tendency to polymerise, in the mere presence of a little hydrochloric or sulphuric 
acid, sulphur dioxide, zinc chloride, &c. Acetaldehyde, for example, gives 
two isomerides : paraldehyde, m.pt. 10, b.pt. 124, and metaldehyde, which 
sublimes at 100 : 

/0-CH(CH 3 K 

3C 2 H 4 = CH 3 -CH/ )>O. 

X 0-CH(CH 8 r 

These no longer react with ammonia, sodium bisulphite, silver nitrate, and 
hydroxylamine, but they yield the aldehyde again when distilled in presence 
of a small quantity of dilute sulphuric acid. 

With alkalis, even dilute alkalis, many aldehydes, especially the more simple 
ones of the fatty series, resinify, whilst some give rise to an alcohol and an acid : 

X 
2HC- f (formaldehyde) + H 2 = CH 3 OH + H- C0 2 H (formic acid). 

^U 

With halogens the aldehydes give substitution products, and with hydrogen 
sulphide various complex products (thioaldehydes, &c.) with characteristic 
odours. 

With hydroxylamine, aldehydes form aldoximes, which are resolved into 
their components when boiled with acids, and yield nitriles when treated with 
dehydrating agents : CH 3 - CHO + NH 2 - OH = H 2 + CH 3 - CH : N- OH. 

A similar action is exhibited by the hydrazines (as hydrochloride or acetate 
in acetic acid solution containing sodium acetate ; the most suitable is phenyl- 
hydrazine), which give characteristic, stable, and often crystalline compounds, 
termed hydrazones : 

CH 3 -CHO + C 2 H 5 -NH-NH 2 (ethylhydrazine) = 
H 2 O + CH 3 -CH : N-NH-C 2 H 6 (acetaldehyde ethylhydrazone) ; 

by nascent hydrogen (4H) this is converted into 2 mols. of primary amine : 

2CH 3 -CH 2 -NH 2 . 

Characteristic of the aldehydes is also the formation of crystalline semi- 
carbazones by the action of the hydrochloride of semicarbazide, NH 2 CO NH-NH 2 
(obtained by the interaction of potassium cyanate and hydrazine hydrate) : 

R-CHO + NH 2 -CO-NH-NH 2 = H 2 + R-CH : N-NH-CO-NH 2 . 

Both the hydrazones and semicarbazones serve for the separation of the 
aldehydes from other substances and for their quantitative determination. 

Finally a characteristic qualitative reaction which is given generally by the 
aldehydes and is very sensitive is that of Schiff. It consists in shaking the 
liquid to be tested with a solution (0-02 per cent.) of fuchsine previously 
decolorised by a current of sulphur dioxide. Traces of an aldehyde produce a 
reddish violet coloration (it is uncertain if pure ketones also give this reaction). 

Another reaction characteristic of the aldehydes and not given by ketones 
is that with benzosulphinehydroxamic acid or with nitrohydroxylaminic acid, 

/OH 

OH-NO:N'OH, which forms hydroxamic acids, R-C^ the latter 



producing a cherry-red coloration with ferric chloride. 

FORMALDEHYDE (or Methanal), H-CHO, is a gas which liquefies at 
20 to a mobile, colourless liquid having the sp. gr. 0-8153 and solidifying 
at 92. It is very soluble in alcohol o^ water, and is placed on the market 



FORMALDEHYDE 



207 



in the form of 40 per cent, aqueous solution 1 under the name of formalin or 
formal ; the commercial product often contains^l2'to 15 per cent, of methyl 
alcohol to prevent separation of polymerised compounds. Indeed, even in 
the cold, formaldehyde readily forms paraformaldehyde, (CH 2 0) 2 , a white solid 
soluble in water, or the crystalline trioxymethylene (or metaformaldehyde), 
(CH 2 0) 3 . Both of these give the aldehyde when volatilised by heat, and they 
are used thus as disinfectants under the names triformol and paraformol. 
Formaldehyde may also give rise to a mixture of saccharine compounds 
(formose). With ammonia it gives, not an aldehyde -ammonia, but hexa- 
methylenetetramine, C 6 H 12 N 4 , which is crystalline and of feebly monobasic 
character. 2 With potassium hydroxide it does not resinify,but yields methyl 
alcohol and formic acid (p. 206). 

A question which has been under discussion for many years is the possible formation 
of formaldehyde as the first product in the natural synthesis of carbohydrates (see Sugar) 
in the leaves of plants, from carbon dioxide under the influence of chlorophyll. 

Numerous sensitive reagents have been employed to detect microscopically the transitory 
formation of formaldehyde in living leaves ; but almost all these reagents are poisonous to 
plants and no decisive results have been obtained, even those of Pollacci (1907), who 
distilled the leaves with water and tested for formaldehyde in the distillate, being doubtful. 
Schryver (1910) has succeeded in establishing the formation of aldehyde in green plants in 
sunlight, by making use of a very sensitive reagent (detecting 1 part of aldehyde per million) 
consisting of a solution of phenylhydrazine, potassium ferricyanide, and hydrochloric 

1 The concentrations of commercial aqueous solutions of formaldehyde can be deduced from the specific 
gravities by means of the following table (Auerbach, 1905) : 



Sp. gr. at 

1-0054 
1-0090 
1-0126 
1-0172 
1-0218 
1-0311 
1-0410 
1-0568 
1-0719 
1-0853 
1-1057 
1-1158 



Grms. of CH 2 O in 100 c.c. 
of solution 

2-24 

3-50 

4-66 

6-51 

8-37 
11-08 
14-15 
19-89 
25-44 
30-17 
37-72 
41-87 



Grms. of CH 2 O in 100 grms. 
of solution 

2-23 

3-45 

4-60 

6-30 

8-0 
10-74 
13-59 
18-82 
23-73 
27-80 
34-11 
37-53 



If the aldehyde is pure and leaves no residue, the percentage by volume, if greater than 23, should be increased 
by about 5. 

The analysis of commercial formalin is based on the following reaction of Blank and Finkenbeiner : 
2CH 2 O + 2NaOH + H 2 O 3 = H 2 + 2H 2 O + 2H-CO 2 Na. Three grammes of the formaldehyde solution are 
poured into a long-necked flask containing 25 c.c. of 2N-caustic-soda solution (free from carbonates), the liquid 
being mixed and 50 c.c. of hydrogen peroxide solution (neutralised or of known acidity) carefully added, 3 minutes 
being taken to make this addition. After 7 to 8 minutes, the excess of alkali remaining is titrated with 2N-sulphurie 
acid. With every cubic centimetre of the 2N-alkali that has reacted corresponds 0-06 grm. of formaldehyde. 
Litmus purified several times with alcohol should be used as indicator. 

The estimation of the aldehyde may also be carried out with ammonia (see succeeding Note). 

Brautigam (1910) suggested determining formaldehyde by adding to it excess of clear calcium hypochlorite 
solution. After a time the solution deposits calcium carbonate, which is filtered, washed, and weighed ; 1 mol. 
of CaCO 3 corresponds with 1 mol. of formaldehyde. 

To determine the methyl alcohol which may be present, 5 c.c. of the solution, diluted with 100 c.c. of water, 
are distilled with an excess of ammonia (about 10 c.c. of concentrated ammonia), 50 e.c. of the distillate being 
collected in a 100 c.c. flask and made up to volume with water. The methyl alcohol in 5 c.c. of this solution, 
which contains only negligible traces of formaldehyde, is determined by the iodine method (see p. 107). 

2 This reaction was proposed by L. Leger in 1883 as a means of estimating formaldehyde in commercial 
solutions : 6CH Z O + 4NH, = (CH 2 ) e N+6H 2 O ; the reaction is, however, slow and the method not very accurate. 
F. Hermann (1911) has rendered it more rapid and exact in the following manner. Pour cubic centimetres of the 
formalin are weighed into a 150 c.c. flask with a ground stopper, and about 3 grms. of pure powdered ammonium 
chloride and exactly 25 c.c. of 2N-caustic soda (equivalent to 50 c.c. of normal soda) added. The flask is stoppered 
and shaken, and, when the mass is cool, 50 c.c. of water and 4 drops of 1 per cent, methyl orange are added and the 
excess of alkali titrated with normal sulphuric acid. Deduction of the volume of acid required from 50 c.c. gives 
the volume of soda used in liberating, from the ammonium chloride, a corresponding amount of nascent ammonia, 
which instantly transforms the aldehyde into hexamethylenetetramine. The latter is, however, monobasic and 
reacts with part of the sulphuric acid, and, in order to obtain the number of grammes of formaldehyde in the 
quantity of formalin taken, the number of cubic centimetres of soda arrived at above must be multiplied by the 
factor 0-06. If the formalin be acid initially, the acidity must be determined separately by titration with soda 
in presence of phenolphthalein and the 50 c.c. of soda increased accordingly. 



208 ORGANIC CHEMISTRY 

acid ; this reagent gives a magenta-red coloration with formaldehyde or with the methylene 
derivative which chlorophyll would form with the aldehyde. 

MANUFACTURE. Formaldehyde is obtained by passing a mixture of methyl alcohol 
vapour and air over copper or platinum gauze or the finely divided metals, which act as 
catalysts (O. Blank, Ger. Pat. 228,697, 1908, obtained quantitative yields by using silver 
precipitated on asbestos). The product is rectified in a column filled with pieces of clay. 
Patents have been taken out for the preparation of formaldehyde by the oxidation of 
methane with oxide of iron, hydrogen peroxide, &c. It is also formed by the electrolysis 
of dilute methyl alcohol, and some years ago a patent was granted for its preparation by 
passing a mixture of formic acid vapour and hydrogen through a tube containing pieces 
of metal (e.g. lead, iron, zinc, nickel, silver, &c.), heated to 300. 

Formaldehyde has considerable antiseptic power, even in aqueous solution. 
It is largely used at the present time as a disinfectant in houses and for the 
preservation of readily putrescible substances (meat, beverages, &c.). Its 
vapour has an acute and penetrating odour and irritates the eyes. On 
account of the property possessed by formaldehyde of combining with proteins 
to form insoluble and stable products, it is used in the manufacture from 
casein of articles of a horny consistency and in making imitation pegamoid ; 
also in preparing photographic films with gelatine, for rendering insoluble 
or hardening the coloured gelatine for textile printing, and for hastening the 
tanning of skins. 

Owing to its great reactivity, it is largely used in organic syntheses, e.g. in 
the manufacture of aniline dyes. 

Various solid and liquid disinfectants containing free aldehyde are prepared 
by means of soaps (soap solutions are also on the market under the names 
of lysoform and ozoform, the starting product in the case of the latter being 
sulphoricinoleic acid). 

A characteristic and very sensitive reaction of formaldehyde is that 
proposed by Rimini, according to whom a mixture of phenylhydrazine 
hydrochloride, sodium nitroprusside and caustic soda is coloured blue even 
by minimum traces of the aldehyde. 

Formaldehyde gives Schiffs reaction even in presence of a certain amount 
of sulphuric acid, whilst acetaldehyde does not. 

The price of commercial 40 per cent, formaldehyde is about 4 per quintal, 
while pure, powdered paraldehyde costs 4s. to 5s. per kilo. 

ACETALDEHYDE (Ethanal), CH 3 -CHO, is a colourless, mobile liquid, sp. gr. 0-801 
(at 0), b.pt. 21, and solidifies at 121. It has an agreeable but suffocating odour, 
and it polymerises with moderate ease, giving the paraldehyde and metaldehyde (see above). 
It dissolves in water, alcohol, or ether, and is readily converted into acetic acid by oxidising 
agents. 

It is prepared by pouring a mixture of 3 parts of 90 per cent, alcohol and 4 parts of 
concentrated sulphuric acid slowly into a solution of 3 parts of potassium bichromate in 
12 of water, the liquid being kept cool meanwhile. The solution is then heated in a reflux 
apparatus on a water-bath and subsequently distilled. The mixture of alcohol, aldehyde, 
and acetal thus obtained is heated to 50 and the aldehyde vapour passed into cold ether. 
On passing ammonia into this solution, crystallised aldehyde-ammonia, CH 3 CH(OH) NH 2 , 
separates ; this, when pressed and distilled with dilute sulphuric acid, gives pure acetalde- 
hyde. The commercial aldehyde is obtained from the foreshots of alcohol distillation, from 
which it is separated by simple fractional distillation. 

It is of importance in many organic syntheses and in .the production of silver mirrors. 
The price of 50 per cent, solutions is 2s. per kilo, that of the 95 to 99 per cent, product 
3s. 6d., and that of the purest aldehyde 15s. 1 

1 The estimation of acetaldehyde is based on the following reaction (Seyewetz and Bardin) : 
2Na 2 SO, + 2CH.-CHO + H a SO 4 = Na a SO 4 + (CH.-CHO, NaHSO,) z . 

The aldehyde is diluted to 7 to 8 per cent, and about 10 c.c. of this solution is poured into 40 c.c. of 10 per cent, 
pure sodium sulphite solution. After the addition of a few drops of neutralised alcoholic phenolphtbaJc.in solution 



UNSATURATED ALDEHYDES 209 

METHYLAL, H.CH(OCH 3 ) 2 , and ACETAL, CH 3 .CH(OC 2 H 6 ) 2 (see p. 204). 

PROP ALDEHYDE, C 2 H 5 -CHO, is found among the tarry products from the 
distillation of wood. Valeraldehyde, C 4 H 9 CHO, boils at 92 and begins to show a diminu- 
tion in solubility in water. Normal heptaldehyde (oenantaldehyde), C 6 H 13 -CHO, is found 
among the products of decomposition of castor oil when this is subjected to distillation in 
a vacuum. Nonyl aldehyde, C 8 H 17 CHO, occurs in the oxidation products of oleic acid or, 
better, in the decomposition products of the ozonide of oleic acid (Harries, Molinari, &c.) ; 
it boils at about 192. 

CHLORAL (Trichloroethanal), CC1 3 -CHO, is the most important halo- 
genated derivative of the aldehydes. It is a dense liquid with a peculiar, 
penetrating odour and boils at 94-4. It is prepared by passing chlorine into 
pure alcohol (96 per cent.) for some days, the hydrochloric acid formed being 
collected. The liquid is then heated with sulphuric acid in a reflux apparatus 
until no further evolution of hydrogen chloride occurs, the chloral being 
distilled and subsequently purified by rectification. Within recent times it 
has also been prepared electrolytically : the bath contains potassium chloride 
solution at 100 and is fitted with a diaphragm ; alcohol is passed into the anode 
chamber, where chlorine is formed, and the hydrogen chloride produced at the 
anode is neutralised by the potassium hydroxide formed (1 h.p.-hour yields 
50 grms. of chloral). 

Chloral gives the reactions of the aldehydes and is used in medicine as an 
anaesthetic and soporific, being first treated with water to form the crystalline 

OTT 
CHLORAL HYDRATE, CC1 3 CH< ::;, which is readily soluble in water 

(m.pt. 57) ; this is one of the few compounds having two hydroxyl groups 
united to the same carbon atom. The crystalline alcoholates or Acetals, 
CC1 3 -CH(OH)-OC 2 H 5 and CC1 3 -CH(OC 2 H 5 ) 2 , corresponding with this hydrate 
are known. 

Chloral costs about 6s. per kilo. 

ALDEHYDES WITH UNSATURATED RADICALS 

ACRYLIC ALDEHYDE (Propenal, Acrolem, or Allyl Aldehyde), CH 2 : CH-CHO, 

is formed when fats are burned, owing to loss of water by the glycerol present ; a similar 
change takes place when glycerol is heated with potassium hydrogen sulphate or boric 
acid. Acrolein, which can also be obtained by the oxidation of allyl alcohol, is a liquid, 
b.pt. 52-4, and has a characteristic pungent odour. When oxidised, it yields acrylic 
acid and, when reduced, allyl alcohol. It has all the chemical properties of the aldehydes 
and polymerises in the course of a few hours. With ammonia, it gives a solid, basic 
condensation product, soluble in water : 2C 3 H 4 + NH 3 = H 2 O + C 6 H 9 ON (acrole'ir.- 
ammonia, which gives picoline on distillation). Owing to its double linking, acroleiin 
unites with 2 mols. of sodium bisulphite and the resulting product, when boiled with acid, 
gives up only one bisulphite molecule, namely, that combined with the aldehyde group. 

CROTONIC ALDEHYDE, CH 3 .CH : CH-CHO, is obtained by distilling the corre- 
sponding aldol, CH 3 .CH(OH).CH 2 .CHO, at 140 or by the dehydrating action of zinc 
chloride or sodium acetate on the saturated aldehyde. It is a liquid boiling at 104 and 
possessing a penetrating odour, and its constitution is shown by the fact that it yields 
crotonic acid when oxidised with silver oxide. 

CITRAL L (or Geranial), (CH 3 ) 2 C : CH.CH 2 .CH 2 -C(CH 3 ) :CH-CHO, is a liquid of 
pleasant odour, b.pt. 229, and occurs in many essences (of mandarin, citron, lemon, orange, 
and most abundantly 60 per cent. in that of Verbena Indiana or lemon -grass, from which 
it is separated by means of its bisulphite compound). It may also be obtained by the gentle 
oxidation of the corresponding alcohol, gerianol, which boils at 230. It exists in two stereo - 
isomeric forms, the cis- and trans-modifications. When oxidised with potassium bisulphate 
at 170, citral is transformed into cymene (with a closed ring) with separation of water. 

the liquid is cooled to 4 to 5 and titrated with normal sulphuric acid until it is decolorised. This occurs when 
no further combination of aldehyde and sulphurous acid takes place. This determination is not affected by the 
presence of alcohol, acetal, or paraldehyde. 

II 14 , 



210 ORGANIC CHEMISTRY 

CITRONELLAL, (CH 3 ) 2 C : CHC-H 2 .CH 2 .CH(CH 3 ).CH 2 .CHO, is found with citral 
in citron oil and boils at 208. 

PROPARGYL ALDEHYDE, CH C-CHO, is a solid, m.pt. 60, and is obtained 
from dibroinoacroleiin by way of the acetal. As it contains the group CH : C, it forms 
metallic derivatives (see p. 91). 

(b) KETONES (R CO R') 

These have the carbonyl group attached to two alcohol radicals and, if 
the latter are similar, are known as simple ketones and, if different, mixed ketones. 
The first member must contain at least three carbon atoms. They present 
the same cases of isomerism as the secondary alcohols, and are metameric with 
the aldehydes. 

Up to the C u -compound they are liquid and beyond that solid, but all 
are less dense than water. They resist feeble oxidation but energetic oxidising 
agents (dichromate and dilute sulphuric acid) break the chain of the ketone 
at the carbonyl group, thus forming an acid with a lower number of carbon 
atoms: CH 3 -CO-CH 3 + 40 = H 2 + CO 2 + CH 3 -C0 2 H. In mixed ketones, 
however, the carboxyl is mainly united to the smaller alkyl radical (R or B'), 
but the acid with the higher alkyl is always formed to some extent. With 
ammonia, the action is different from that in the case of aldehydes : water is 
eliminated from 2 or 3 mols. of ketone and di- and tri-ketonamines (or acetona- 
mines), e.g. C 6 H 13 ON, formed. Further, the ketones do not polymerise, but they 
form condensation products. They do not react with ammoniacal silver 
solutions or with Fehling's solution, and are hence not reducing in character 
(difference from aldehydes). 

With phosphorus pentachloride they give the corresponding dichloro- 
derivatives ; for instance, acetone gives 2-dichloropropane, CH 3 -CC1 2 -CH 3 . 

On reduction, they yield secondary alcohols, and with very energetic oxidis- 
ing reagents (H 2 2 , &c.), they form characteristic polymerised ketonic per- 
oxides, e.g. [(CH 3 ) 2 C0 2 ] 2 , [(CH 3 ) 2 C0 2 ] 3 . With ethyl orthoformate they give 
acetals, (CH 3 ) 2 C(OC 2 H 5 ) 2 , and similarly with mercaptans they form Mercaptols, 
e.g. (CH 3 ) 2 C(SC 2 H 5 ) 2 , which, when oxidised with permanganate, gives Sulphonal, 
(CH 3 ) 2 C(S0 2 C 2 H 5 ) 2 . 

Ketones, which generally contain the group CH 3 -CO- form, with sodium 
bisulphite, compounds which are crystalline and hence readily separable from 
other substances : 

(CH 3 ) 2 CO + S0 3 HNa = (CH 3 ) 2 C<j?;? N (sodium acetonebisulphite). 

- 3 

This compound crystallises also with 1 mol. H 2 and yields acetone easily 
when heated with dilute soda solution. 

With hydrocyanic acid, ketones give the cyanohydrins or nitriles of higher 

OH 

acids : e.g. (CH 3 ) 2 C< CN . 

With hydrogen sulphide, but only in presence of HC1, &c., they form 
trithioketones, which on heating give simple thioketones. 

With hydroxylamine, ketones readily form the so-called ketoximes, 
R^CrN-OH, 1 similar to aldoximes, and with phenylhydrazine they give 
phenylhydrazones, just as aldehydes do : 



(CH 3 ) 2 CO + NH 2 -OH = H 2 + (CH 3 ) 2 C rN-OH (acetoxime}. 

1 For the ketoximes (as for the aldoximes) stereoisomerides exist as a consequence of the stereoisomerism of 
nitrogen (see p. 22), which has been studied by Beckmann, V. Meyer, Auwer, H. Goldschmidt, Hautzsch arid 
Werner, Minunni, &c. Thus for aldoximes we have the two following stereoisomeric configurations : 

R C H K C H 

II (syw-aldoximo) ;iml || (rtnti-aldoxime), 

N OH OH N 



K E T O N E S 211 

Under certain conditions, e.g. by the action of acetyl chloride, ketoximes 
undergo an atomic transposition by which they are converted into amides, 
substituted in the ammo-group (Beckmann rearrangement), these being tauto- 
meric with the ketoximes : 

R-C-R' R-C:O 

II - I 

N-OH NHR'. 

The action of nitrous acid (or its esters) yields isonitrosoketones : 
CH 3 -CO-CH 3 + N0 2 H = H 2 + CH 3 -CO-CH : N-OH. 

In presence of various reagents, e.g. lime, potash, sulphuric or hydrochloric 
acid, &c., the ketones lose water and undergo condensation (whilst aldehydes 
polymerise) : 3(CH 3 ) 2 CO = 2H 2 + C 9 H 14 0. Similar condensations occur 
between ketones and aldehydes. 

The FORMATION OF KETONES takes place in the dry distillation of 
wood or of the calcium or barium salts of many organic acids or on simple 
heating of the latter or the anhydrides of the acids in presence of phosphorus 
pentoxide : (CH 3 C0 2 ) 2 Ca = CaC0 3 + CH 3 CO CH 3 (acetone) ; if mixed 
ketones are required, a mixture of the salts of two different acids is used. x Note- 
worthy also is the formation of ketones by the oxidation of secondary alcohols 
(see p. 103): CH 3 -CH(OH)-CH 3 + = H 2 + CH 3 -CO-CH 3 . Also, with 
powdered metals (Sabatier and Senderens, p. 34), secondary alcohols give 
ketones, hydrogen being eliminated. 

Ketones are also formed by the action of water in the hot on chlorinated 
hydrocarbons having two chlorine atoms united to the same carbon atom : 
,(CH 3 ) 2 CC1 2 + H 2 = 2HC1 + CH 3 -CO-CH 3 . 

Another general method of preparing ketones is based on the interaction 
<of zinc alkyls and acid chlorides, the additive product formed being immediately 
decomposed with water so as to avoid the formation of tertiary alcohols : 
2CH 3 -CO-C1 + Zn(C 2 H 6 ) 2 = ZnCl 2 + 2CH 3 -CO-C 2 H 6 (methyl ethyl ketone). 

Acetone is formed when acetic acid vapour is passed over a heated acetate or 
base. 

ACETONE (Propanone), CH 3 -CO-CH 3 , is found in small quantities in the 
human organism, where it is formed in larger amounts during certain diseases 
(diabetes, acetonuria). It is formed in considerable quantities in the dry 
distillation of wood and of other organic substances (calcium acetate, sugar, 
gum, wool -fat, &c.). It is a liquid with an ethereal odour and a characteristic 
burning taste, b.pt. 56-3, sp. gr. 0-7921 at 18. It solidifies at 94 and is 
soluble in water (from which it separates on addition of soluble salts), alcohol, 
ether, and chloroform ; it dissolves fats, resins, ethereal oils, nitrocellulose, 
&c., and is readily inflammable. 

In aqueous solution rendered alkaline with sodium carbonate, it is oxidised 
with ease by potassium permanganate, and chromic acid converts it into acetic 
acid and carbon dioxide. With sodium it forms sodium fi-allyloxide : 

CH 3 -C(ONa) : CH 2 . 

whilst for ketoximes, stereoisomerides exist if the two alkyl radicals are different : 

B^C It' B^-C R' 

I! (gyw-ketoxime) and II (antf-ketoxime) 

ff OH OH N 

These isomerides are transformable one into the other, and in addition to their physical differences exhibit also 
chemical differences, e.g. in regard to the readiness with which they lose water (aldoximes giving nitrites). 

1 This reaction can be used to demonstrate the normal constitution (absence of branching from the carbon 
chain) of acids, ketones, and hydrocarbons (paraffins), since on distilling an organic barium salt with a normal C 
chain with barium acetate, a C ll + 1 ketone is obtained which should also be normal, as the methyl group of the 
acetate unites with the carbonyl at the end of the chain of the acid. On oxidation, this ketone gives a _ ! acid 
which will also be normal. From this are prepared the ketone and then a C,, _ , acid, so that normal products are 
always obtained (also the corresponding hydrocarbons) by this gradual descent from a high acid of which the 
constitution is known to be normal. 



212 ORGANIC CHEMISTRY 

In the crude form, it is used in lac and colour factories and in a more or less 
pure state in the manufacture of iodoform. Also at the present time pure 
acetone is employed in large quantities for gelatinising smokeless powders and, 
owing to the intense burning taste it imparts, as a denaturant for spirit, from 
which it cannot be separated by distillation. 

Industrial Preparation. Calcium acetate obtained from pyroligneous acid (which see) 
is subjected to dry distillation, the temperature being controlled so that it does not exceed 
300 ; the vapours evolved are rapidly cooled and condensed, giving crude acetone. In 
order to avoid superheating and irregularity during the distillation, moist calcium acetate 
is sometimes employed. The acetone vapour escaping condensation is easily recovered 
by passing it through towers down which a spray of sodium bisulphite solution falls ; this 
fixes the acetone, which can be liberated by distilling the solution in presence of an alkali. 
In France, Buisine has utilised the wash-waters of dirty wool to prepare acetone from the 
fat they contain. This process has been tried on an industrial scale at Roubaix, but as yet 
without marked success. 

The crude acetone is purified by digesting it with quicklime and then distilling it from 
sodium hydroxide and subsequently over sodium sulphite. 

Crude, impure acetone (oil of acetone) is sold at 3 8s. per quintal if dark or 4 if pale. 
Acetone for industrial purposes (85 to 90 per cent.) sells at 6, the pure product at 6 16s., 
and the chemically pure (98 to 100 per cent. ) at 7 8s. per quintal. The bisulphite compound 
is also placed on the market at 4 per quintal (or 14s. per kilo for the chemically pure). 
In 1908 England consumed 1500 tons of acetone (worth 100,000), which was almost all 
imported from the United States. In 1910 England imported 1100 tons of acetone, of the 
value of 57,000. In 1910 Italy imported 438 hectols. of the value of 2600. 

Tests for Acetone. These are of especial importance for explosive factories, where a 
highly purified product is required. It should dissolve in water in all proportions without 
rendering it turbid. When mixed with a little 0-1 per cent, permanganate solution it 
should retain the colour for some minutes. If acetone contains water, when mixed with 
an equal volume of light petroleum (boiling at 40 to 60) two layers are formed ; if no 
water is present, the liquids mix perfectly. At least 95 per cent, of it should distil between 
56 and 56-5, and it should not redden blue litmus paper. Kramer's quantitative iodo- 
metric test (see p. 107) should indicate at least 98 per cent, of acetone ; Strache's method, 
in which phenylhydrazine is employed, may also be used. 1 The detection of acetone in 
other substances is effected by means of orthonitrobenzaldehyde and caustic soda, which 
convert acetone into indigo. 

MESITYL OXIDE, CH 3 .CO-CH : C(CH 3 ) 2 , is an aromatic liquid boiling at 132. 

PHORONE, (CH 3 ) 2 C : CH-CO-CH : CMe 2 , forms yellow, readily fusible crystals, and 
is obtained by saturating acetone with hydrogen chloride. 

BUTANONE (Methyl ethyl ketone) , CH 3 C-O.C 2 H 5 , is a liquid, b.pt. 81, and is 
contained in wood-spirit. 

KETENES 

These constitute a group of substances discovered by Staudinger since 1905. Although 
they contain the ketonic group, CO, they differ markedly from the ketones in their great 
reactivity, since they are unsaturated compounds, that is, unsaturated ketones. 

They are derived from the type R 2 C : CO, which was formerly thought incapable of 
existing in the free state. The residues, R, may be either aromatic or aliphatic hydro- 
carbon radicals. All these compounds can be derived from KETENE, CH 2 : CO, which is a 
colourless gas, b.pt. 56, m.pt. 151, and was prepared in 1908 ; it has a disagreeable 
odour (resembling somewhat those of chlorine and acetic anhydride), is poisonous and even 
in small quantity produces intense headache. It is easily polymerised (by metallic chlorides 
or tertiary bases), yielding a coloured resin. It decolorises ethereal bromine solutions 

1 Strache' method for the indirect estimation of compounds containing carbonyl groups (aldehydes and ketones). 
When to a solution of an aldehyde or a ketone is added an excess of a phenylhydrazine solution of definite strength, 
the excess of the latter which does not combine may be deduced from the amount of nitrogen liberated on 
decomposing (oxidising) in the hot with Fehling's solution [a mixture in equal volumes of the following two 
solutions : (a) 69-26 grms. of air-dried copper sulphate crystals dissolved in water to 1 litre ; (6) 346 grms. of 
Rochelle salt dissolved in 800 c.c. of water + 105 grms. sodium hydroxide, the whole made up to 1 litre with 
water] : C,H B NH-NH 2 + O = H 2 O + C,H, + N 2 . The test is made on 0-2 to 0-6 grm. of substance (aldehyde 
or ketone) and the details of the operation are described in Zeitschr. fi'ir analyt. Chemie, 1892, p. 573, or in Hans 
Meyer's ' Determination of Radicals in Carbon Compounds," 1899, p. 65. 



DERIVATIVES OF GLYCOL 213 

instantly, and, unlike disubstituted ketenes, does not undergo oxidation in the air. The 
most stable and best characterised of these compounds are dimethyl-, (CH 3 ) 2 C : CO, and 
diphenyl-ketene, (C 6 H 5 ) 2 C : CO ; monomethyl-, CH 3 -CH:CO, and monoethyl-ketene, 
C 2 H 5 CH : CO, have properties similar to those of carbon suboxide, O : C : C : C : 0, and 
resemble the isocyanates in their great reactivity. The disubstituted ketenes are coloured 
and readily oxidise in the air ; two molecules condense with one of a base (pyridine, quino 
line), and they unite with the C : N group (benzylideneaniline) and with the C : group 
(quinones), forming /3-lactams and /3-lactones. All the ketenes combine with water, 
alcohols, or amines at the double carbon -linking, giving compounds of an acid nature. 
The monosubstituted ketenes are also called aldoketenes and the disubstituted ones, 
ketoketenes. They are usually prepared by the action of zinc on an ethereal solution of 
acid halogen derivative with a second halogen in the a -position : 

CH 3 .CHBr.COBr + Zn = ZnBr 2 + CH 3 -CH : CO. 

a-bromopropionyl bromide 

The ketenes are easily transformed into acids ; and those that condense (the ketoketenes) 
with unsaturated groups (ethylene and carbonyl compounds, Schiff's bases, thioketones, 
nitroso-and azo -compounds) form compounds with a closed chain of four or six carbon atoms, 
these being resolved into two unsaturated compounds when heated. The aldoketenes 
undergo polymerisation more readily, giving derivatives of cyclobutane which decompose 
on heating. 

B. DERIVATIVES OF POLYHYDRIC ALCOHOLS 

The ethers of polyhydric alcohols are generally prepared by the methods used for ethers 
of the monohydric alcohols and have many properties in common with these. 

ETHYL ETHER OF GLYCOL, OH-C 2 H 4 .OC 2 H 5 , boils at 127 and the DIETHYL 
ETHER, C 2 H 4 (OC 2 H 5 ) 2 , at 123. Of the esters of glycbl, the mono- and di-acetates, 
C 2 H 4 (OC 2 H 3 O) 2 , which are liquids soluble in water, are well known. Glycolchlorohydrin 
or Monochloroethyl Alcohol, OH-CH 2 -CH 2 -C1, boils at 130, is soluble in water and 
is prepared by passing hydrogen chloride into hot glycol. GLYCOLSULPHURIC ACID, 
OH C 2 H 4 -O-SO 3 H, is the sulphuric ester of glycol. Glycol Dinitrate, C 2 H 4 (N0 3 ) 2 , is 
a yellowish liquid insoluble in water and explode son heating ; it is prepared by treating 
glycol with nitric -sulphuric mixture (see later, Nitroglycerine). It is readily hydrolysed 
by alkali. 

ETHYLENECYANOHYDRIN, CH 2 : C : N-CH 2 .OH, is isomeric with Ethyl- 
idenecyanohydrin, CH 3 -CH(OH).CN. Ethylene Cyanide, C 2 H 4 (CN) 2 , obtained by the 
action of potassium cyanide on ethylene bromide, forms a crystalline mass ; on hydrolysis 
it gives Succinic Acid, C 2 H 4 (COOH) 2 . 

ETHYLENE OXIDE, CH 2 -0-CH 2 , isomeric with acetaldehyde, is a liquid with an 
ethereal odour, sp. gr. 0-898 (at 0), b.pt. 12-5 ; although neutral in its reaction it 
precipitates certain metallic hydroxides from solutions of their salts. It is formed on 
distilling glycolchlorohydrin with potash. It reacts readily and dissolves in water with 
gradual formation of glycol. 

The following compounds are also known : Ethylene M onothiohydrate, C 2 H 4 (OH)-SH ; 
Glycol Mercaptan (Ethan-l : 2-dithiol), C 2 H 4 (SH) 2 ; Dithioglycol Chloride, (C 2 H 4 C1) 2 S, which 
is a very poisonous liquid. Hydroxymethylsulphonic Acid, CH 2 (S0 3 H)-OH, is solid and is 
obtained from methyl alcohol and fuming sulphuric acid. MethylenedisulpJionic (or 
Methionic) Acid, CH 2 (SO 3 H) 2 , is formed from acetylene and fuming sulphuric acid, by way 
of Acetaldehydedisulphonic Acid, CHO-CH(S0 3 H) 2 , which with lime gives formic acid and 
methionic acid ; the latter is isomeric with ethylsulphuric acid, but cannot be hydrolysed. 
Hydroxyethylsulphonic Acid, OH-CH 2 -CH 2 -S0 3 H (Isethionic Acid), is a crystalline mass 
formed by treating ethyl alcohol with sulphur trioxide ; ethylene with S0 3 gives Carbyl 
Sulphate, C 2 H 4 (S0 3 ) 2 , which forms sulphuric and isethionic acids with water. 

Glycol forms also two amines: Hydroxyethylamine, OH C 2 H 4 NH 2 . (primary mono- 
valent base, or Hydroxyalkyl Base, or Hydramine), and Ethylenediamine, C 2 H 4 (NH 2 ) 2 
(primary divalent base). These may also be regarded as derived from one or two molecules 
of ammonia, in which all or part of the hydrogen is substituted by the hydroxyethyl group, 
C 2 H 4 -OH, or by ethylene, C 2 H 4 <^. Thus, such compounds as the following are known : 
NH 2 -C 6 H 4 .OH;' (NH 2 ) 2 C 2 H 4 ; NH(C 2 H 4 .OH) 2 , Dihydroxydiethylamine ; N(C 2 H 4 .OH) 3 , 



214 ORGANIC CHEMISTRY 



Trihydroxytriethylamine ; (NH) z (Q^li) z ,Dieihylenediamine; N 2 (C 2 H 4 ) 3 , Triethylenediamine ; 
and finally quaternary bases containing alkyl groups, e.g. CTioline (or Bilineurine), 
(CH 3 ) 3 N( OH) C 2 H 4 OH, or HydroxyetTiyltrimethylammonium Hydroxide, which is 
obtained from trimethylamine and ethylene oxide and is found in the bile, in egg-yolk, 
and in the brain in the form of lecithin (see later) ; it is not poisonous, but when oxidised 
with nitric acid yields Muscarine, CH(OH) 2 -CH 2 -N(CH 3 ) 3 -OH, which has a distinct 
poisonous action. On putrefaction, choline gives neurine (or Trimethylvinylammonium 
hydroxide), N(CH 3 ) 3 (C 2 H 3 )-OH, which is also poisonous. Many of these com- 
pounds are formed in putrefying proteins and in dead bodies, and are called 
'ptomaines. 

These bases are prepared by the same methods as the monovalent bases (p. 200), the 
primary diamines, for example, being obtained by reducing the nitriles, C n H 2n (CN) 2 , in 
hot alcoholic solution by means of sodium or from ethylene bromide and alcoholic ammonia 
at 100. They are liquid or solid substances and have certain of the characters of ammonia. 
Pentamethylenediamine or Cadaverine, NH 2 CH 2 CH 2 CH 2 ^^2 CI^ NH 2 , boils at 179 
and, being a ^-diamine, can form Piperidine, C 5 H 11 N, with separation of ammonia. 

NH 

Diefhylenediamine. or Piperazine, C 2 H 4 <^ > ,-p,>>C 2 H4, melts at 104 and boils at 146. 

Tetramethylenediamine is called also Putrescine. 

TAURINE (Aminoethylsulphonic Acid), NH 2 -CH 2 -CH 2 -S0 3 H, is found in com- 
bination with cholic acid (as Taurocholic Acid) in the bile of various^animals and also 
in the lungs and kidneys. It forms monoclinic prisms soluble in hot water but insoluble 
in alcohol, and has a neutral reaction, the basic and acid groups neutralising one another. 
It is not hydrolysable. 

Of the derivatives of Olycerol, the CTilorTiydrins or esters of hydrochloric acid are of 
interest ; they are liquids soluble in alcohol or ether, and, to a less extent, in water. With 
hydrochloric acid, glycerol forms the Monochlorhydrin, C 3 H 5 (OH) 2 C1, of which two 
isomerides (- and ft-) are known, and the Dichlorhydrin, C 3 H 5 (OH)C1 2 , also existing in 
two isomeric forms. Either of these, when treated with PO 5 , gives the trichloro- 
derivative, C^sCl^ 1 At the present time interest attaches also to the formins and acetins, 
which are used in the manufacture of non -congealing explosives. 2 

GLYCIDE ALCOHOL, CH 2 -CH-CH 2 .OH, is a liquid, b.pt. 162, soluble in alcohol 

\0/ 

or ether, and also in water, with which it gives glycerol again ; with hydrochloric acid 
it gives the chlorhydrin. It may be regarded as derived from glycerol by the removal of 
a molecule of water, and is prepared by the separation of HC1 from the a-monochlorhydrin 
by means of baryta. It is isomeric with propionic acid and reduces ammoniacal silver 
solution. Separation of hydrogen chloride from the dichlorhydrin yields Epichlorhydrin, 
CH 2 C-HCH 2 C1, which may be regarded as the hydrochloric ester of glycide alcohol. 

\0/ 

It boils at 117, has an odour like that of chloroform and is insoluble in water. It is 
isomeric with propionyl chloride and monochloroacetone. 

GLYCEROPHOSPHORIC ACID, OH,CH 2 .CH(OH).CH 2 .0-PO(OH) 2 , is optically 
active, as also are its calcium and barium salts (laevo -rotatory). It is interesting from the 
fact that when the hydroxyl-groups are esterified with palmitic, stearic, or oleic acid, and 

1 According to Ger. Pat. 180,668, the monochlorhydrin is made by heating for 15 hours in an autoclave at 
120 a mixture of 100 parts of glycerol with 150 parts of hydrochloric acid (sp. gr. 1-185). The water is distilled 
off and the residue subjected to fractional distillation in a vacuum (15 mm. pressure) ; after the acid and water 
have been eliminated, the monochlorhydrin distils over at 130 to 150, and the unaltered glycerine at 165 to 180. 
If it is to be nitrated and used for explosives, it is sufficient to get rid of the water and acid. According to Fr. Pat. 
370,224, the monochlorhydrin may also be obtained by shaking glycerine with the calculated quantity of 
sulphur chloride at a temperature of 40 to 50 ; the water formed is distilled off in a vacuum at 60 to 70. The 
a-Monochlorhydrin, CH 2 C1-CH(OH)'CH 2 -OH, is obtained (according to Fr. Pat. 352,750) bypassing hydrogen 
chloride into glycerine heated to 70 to 100. 

Like glycerine itself, the chlorhydrins are easily nitrated, yielding non-congealing explosives (gee Inter). 

3 MonoaceMn, C.3H 6 (OH) ? (O'COCH3),isobtained by heatingfor lOto 15 hoursat 100 a mixture of 10 parts 
of glycerol with 15 parts of 40 to 100 per cent, acetic acid, the weak acetic acid (25 to 30 per cent.) that distils 
over being condensed separately. Ten parts of 70 per cent, acetic acid are then added and the weak acid up 
to 40 per cent., which distils at 120 collected apart. After this the temperature is raised in 3 hours to 250, 
the weak acid still being kept separate. The crude monoacetin remaining contains about 44 per cent, of combined 
acetic acid and about 0-8 per cent, of the free acid. This acetin is soluble in water and serves well for the manu- 
facture of explosive and non-congealing nitroacetins (see Explosives) and for gelatinising the nitrocellulose 
of smokeless powders (Vender Ger. Pat. 226,422, 1906), 



EXPLOSIVES 215 

the phosphoric residue united to choline, it gives rise to the important group of lecithins, 
which are optically active : 

OR CH 2 CH(OR') CH 2 . PO(OH) - O CH 2 CH 2 N(CH 3 ) 3 OH, 

where R and R' are fatty acid residues. 

Lecithins are found in the brain, yolks of eggs, and many seeds and are soluble in 
alcohol, and, to a less degree, in ether ; they give salts with acids and with bases and yield 
solid compounds with chloroplatinic acid or cadmium chloride. They are saponified by 
baryta, with formation of choline, fatty acids, and glycerophosphoric acid. 

Of the nitric esters of glycerine, the most important is trinitroglycerine, 
or trinitroglyceric ester, C 3 H 5 (ON0 2 ) 3 , which is one of the most powerful 
explosives. We shall hence study it from the industrial standpoint, first dis- 
cussing certain general notions concerning explosives. The manufacture of the 
latter constitutes one of the most interesting industries of organic chemistry, 
partly because of the varied mechanical appliances which it requires. 

EXPLOSIVE SUBSTANCES 

The name explosive substances, or explosives, is given, in general, to those 
solid and liquid bodies which, under the influence of heat, percussion, 
electrical discharge, &c., are transformed instantaneously and completely 
or nearly so into a gaseous mass with an enormously increased temperature. 

If the reaction takes place in a closed space, the gases thus produced and 
heated exert a very considerable pressure which can be immediately trans- 
formed into mechanical work, the enclosing substance and all the surround- 
ing objects being shattered with great violence and noise. Such a phenomenon 
(or effect) constitutes a so-called explosion, and if it attains very great rapidity 
and power it is termed a detonation. For a constant quantity of gas produced 
in an explosion, the effect will be the greater the higher the temperature 
developed in the reaction. 

THEORY OF EXPLOSIVES. The chemical reactions and physical phenomena 
of explosives are produced under conditions differing greatly from those in which physical 
and chemical properties of substances are usually studied. The pressures, temperatures, 
and velocities with which we have to deal in ordinary phenomena are of a very different 
order from that of the enormous pressures of the gases in the interior of the earth's crust, 
which are measured in hundreds of thousands or millions of atmospheres. So also the 
temperatures in various stars, e.g. in the sun, reach thousands of degrees, and the velocities 
of the planets hundreds of kilometres per second. The phenomena now to be considered, 
although they do not attain these enormous magnitudes, still do approach them. Indeed, 
explosions give pressures of tens of thousands of atmospheres, temperatures of thousands 
of degrees, and velocities (of projectiles) of thousands of metres per second. 

Almost all explosive substances contain oxygen (furnished by chlorates, nitrates, &c.), 
only very few, such as nitrogen chloride and iodide, and aniline fulminate, being without 
it. Mixtures of oxidising agents with readily combustible substances (sulphur, carbon, 
sugar, &c.) are explosive, but they are less powerful than those composed of single com- 
pounds which explode by themselves. This is because the elements necessary for complete 
combustion are in much greater proximity, being present in the molecule of the explosive 
itself ; examples of such explosives are nitroglycerine, guncotton, mercury fulminate, 
picric acid, &c. 

The determination of the theoretical power of an explosive requires a knowledge of : 

(a) the chemical reaction accompanying the explosion, so that the heat of the reaction, 
the temperature, and the volume and relative pressure of the gases formed can be deduced ; 

(b) the velocity of the reaction. In order to understand the theory of explosives, it is indis- 
pensable to call to mind the fundamental principles of thermochemistry and of thermo- 
dynamics, for which the reader is referred to the brief account given in vol. i, pp. 49 
and 57. 



216 ORGANIC CHEMISTRY 

(a) The chemical reaction is deduced from the difference in composition between the 
explosive and the products resulting from the explosion. When there is sufficient oxygen 
in the explosive to produce complete combustion, the nature and quantities of the gases 
can be calculated a priori, and from their heats of formation their temperature can be 
deduced. The total combustion of nitroglycerine, when exploded in a closed space, gives 
the following products (a) : 2C 3 H 5 (NO 3 ) 3 = 6C0 2 + 5H 2 + 3N 2 + 0. 

When there is deficiency of oxygen, as in guncotton and other substances, it is not easy 
to foretell the products of the reaction, as these vary with the conditions in which the explo- 
sion occurs, and usually several reactions take place simultaneously. Further the gases 
found after the explosion of such products are probably not always those formed at the 
instant of the explosion, as at such high temperatures certain substances (H 2 O, CO 2 , &c.) 
may undergo dissociation with absorption of heat. 1 

(b) The heat developed in the explosion is deduced by calculation from the thermo- 
chemical data of the equation, but the practical result is not in accord with the theoretical 
calculation, since part of the heat (25 to 30 per cent.) that should theoretically be developed 
is transformed into mechanical work, which is what is utilised in practice. In calculating 
theoretically the heat of explosion, the heat of formation of the explosive (from the elements) 
is subtracted from the heat that should theoretically be developed in the reaction. The 
heat of explosion varies, however, according as it is determined at constant volume or 
at constant pressure ; in the latter case the explosion of nitroglycerine, for example, is 
effected in the open air, since then the volume varies, but the pressure is only that of 
the atmosphere. 

The heat cf formation of nitroglycerine from its elements (see p. 25) is given by the 
following equation (6) : C 3 + H 5 + N 3 + O 9 = C 3 H 5 (NO 3 ) 3 + 98 Gals. 

The heat of reaction of nitroglycerine can be calculated from equation (a) given 
above, from which it is seen that 2 mols. or 454 grms. of nitroglycerine yield 
6C0 2 + 5H 2 + 3N 2 + O. The heat of formation of 6C0 2 is 6 x 97 = 582 Cals., 
and that of 5H 2 0, 5 x 68-5 = 342-5 Cals. For the nitrogen and oxygen there is no 
development of heat since they are not combined, so that the total heat of reaction 
calculated on the gases formed in the explosion of 2 grm.-mols. of nitroglycerine will 
be 924-5 (i.e. 582 + 342-5) Cals. From this must be subtracted the heat of formation 
from the elements of 2 mols. of nitroglycerine, since on decomposing under these 
conditions of temperature the explosive first of all liberates its atoms, absorbing as 
much heat as is evolved in its formation from its elements (reaction b), i.e. 196 (98 x 2) 
Cals. per 2 mols. The atoms thus liberated combine immediately to give the gases 
which result from the explosion, the heat of formation of which has already been 
calculated. 

The true theoretical heat of explosion at constant pressure for 454 grms. of nitroglycerine 
will hence be 728-5 (i.e. 924-5 - 196) Cals., or for a kilo, 1603 Cals. The heat of reaction 
at constant volume the explosion occurring in a closed vessel is rather higher, the 
heat corresponding with the expansion of the gas (see vol. i, pp. 26 and 50) not being 
absorbed as no expansion takes place ; theoretically the heat at constant volume is calcu- 
lated to be 1621 Cals. per kilo. 2 Serrau and Vieille, by direct practical measurements, 
found the heat of explosion of nitroglycerine at constant volume to be 1600 Cals., which 
confirms the accuracy of the calculation. 

With substances which themselves contain sufficient oxygen for complete combustion 

The following Table gives the percentage compositions of the gases resulting from the normal explosion of 
various explosives in the calorimetric bomb : 

CO CO 2 O 2 CH 4 Hj N 2 

Nitrocellulose powder 46-87 16-8 0-08 1-26 20-44 14-9 



Gelatine dynamites. 
Carbonite 
Picric acid 
Trinitrotoluene 



34-0 32-68 0-75 10-0 21-0 

36-0 19-2 2-8 27-6 14-4 

61-05 3-46 0-34 1-02 13-18 21-1 

57-01 1-93 0-11 . 20-45 18-12 



For every gramme-molecule of a substance passing from the solid or liquid to the gaseous state, owing to 
the new volume occupied, 590 small calories (vol. i, pp. 26 and 50) are absorbed. In the explosion of 2 mols. 
of nitroglycerine, 14-5 mols. of gas (6C0 2 + 5H 2 O -f 3N 2 + O) are formed, and these, on expanding, will 
absorb 14-5 x 590 = 8550 small calories, or 8-5 Cals. per 454 grms. of nitroglycerine, i.e. 18 Cals. per kilo. 
This, added to 1603, the heat of reaction at constant pressure, gives 1621 Cals. as the. heat of reaction at constant 
volume. 



217 

during explosion, it is not easy to calculate theoretically the heat of explosion, since the 
products of the reaction are not exactly known ; in such cases, various direct practical 
determinations must be made. 

It is not easy to calculate theoretically the temperature of the gases at the moment of 
explosion, since the specific heat of the gases at such high temperatures cannot be deter- 
mined, but is certainly rather higher than the ordinary value. Further, at such tem- 
peratures dissociation phenomena occur which cannot be defined ; these, however, lower 
the temperature, although not greatly, since with the great pressures developed the disso- 
ciation is minimal. On the other hand, with the means we possess, it is not possible to 
measure these temperatures directly and only approximately can they be determined 
for black powder. In general, however, they are very high and in some cases exceed 4000 
(for instance, by burning ballistite in the air, platinum withm.pt. 1800 is easily melted), 
but even these temperatures, deduced indirectly, are much lower than those calculated 
theoretically. 1 

The temperature of ignition does not usually coincide with the temperature of explosion 
since explosion is caused not so much by the temperature as by the pressure and other 
factors to be considered later ; so that for explosion to occur, special conditions (detonators) 
are necessary. But for some substances, e.g. black powder, non -compressed guncotton, &c., 
the temperature of ignition, given in the following Table, is identical or almost so with that 
of explosion : 

Fulminate of mercury . . . 200 

Non -compressed guncotton . . 220 to 250 

Nitroglycerine . . . .218 (explodes'at 240 to'250) 

Black powder *>'' 288 

There are thus explosives which explode when merely ignited with a match and others 
which are exploded indirectly by means of detonators^ 

The mechanical work, in kilogram-metres, yielded by an explosive is calculated by 
multiplying the number of calories developed in the explosion of 1 kilo of the substance 
by the mechanical equivalent of heat (= 425, see vol. i, pp. 50 and 51). For various 
explosives this mechanical work (or potential energy) is given in the following Table : 

Nitroglycerine . (1 kilo) = 1600 Gals, x 425 = 680,000 kilogram -metres 

Explosive gelatine . . . = 1530 = 650,000 

Dynamite . . . . = 1178 = 500,000 

Guncotton . . . . = 1074 = 456,000 

Fine sporting powder . . = 849 = 360,000 

Potassium picrate . . . = 780 = 330,000 

Fulminate of mercury . . = 403 = 170,000 

Nitrogen chloride . ' . . = 339 = 144,000 

Owing to various causes, the total theoretical energy of explosives cannot be utilised 
practically ; e.g. the expansion of the gases at the moment the projectile leaves the cannon 
or gun, the friction, the heating of the barrel, &c., all constitute losses of the useful effect 
of the explosive. 

The volume of the gases formed in the explosion can be calculated with reference to 
and 760 mm., taking account of the fact that at the moment of explosion the water is 
in the state of vapour. But in practice it is of more importance to calculate the volume 
at the temperature of explosion, when a knowledge of the gases formed is possible, as is 
the case with nitroglycerine, and, in general, with explosives containing sufficient oxygen 

1 Indeed, water-vapour, formed from H a + 0, should have theoretically a temperature of 7927 (see Calcula- 
tion, vol. i, p 378), but in the most favourable theoretical conditions the oxy-hydrogen flame does not exceed 
2500. For carbon dioxide the heat of formation is 97,000 cals., and the specific heat 0-217, so that for 44 grms. 

97 000 
of C0 2 gas (grm.-mol.) the temperature attainable would be TJTTiESJS = 10,160, and allowing for the fact 

that along with the 6 mols. of CO 2 and 5 of H 2 O, the 3 mols. of N 2 and half a mol. of oxygen formed in the explo- 
sion of nitroglycerine are also to be heated the theoretical temperature of the gases from the explosion would 

ft 

be about 7000. This theoretical temperature is determined in general by the formula t = - TTTT ^-^ 

where p, p', p" . . . are the weights of the gases formed in the explosion, s, s', s" . . . their specific heats, and 
C the total heat in caloriesi 



218 ORGANIC CHEMISTRY 

for their complete combustion. It is, however, not easy to calculate the volume of gas 
formed by products containing an insufficiency of oxygen, like guncotton, &c., with which 
the gases vary quantitatively and qualitatively according to the type of explosion ; in such 
cases the volume must be determined directly. 

The volume of gases is calculated (see vol. i, p. 34) by means of the general formula, 

7 (1 + 0-00367 1) .. 

v t - p 

where V f is the required volume at the temperature of explosion t, V is the volume at 
and 760 mm. pressure (which can be found from the weight of the gaj?es formed), and 
0-00367 is the coefficient of expansion for all gases. For such high temperatures and 
pressures, however, the coefficient of expansion is rather higher than that resulting from 
Gay-Lussac's and Boyle's laws, but this difference is compensated for by the somewhat 
higher specific heat of the gas at high temperatures, in consequence of which more than 
the theoretical quantity of heat is absorbed. 

The pressure of the gas is deduced from the general formula given above, V f being 
diminished by the volume v of the mineral, non-gasifiable residue (in the case of dynamite 
or other mixtures), so that : 

+ 0-00367 Q 







V t -v 



with nitroglycerine, guncotton, &c., v = 0. P is the maximum theoretical force of an 
explosive, starting from its volume (solid) at the ordinary temperature, but the effect of 
a given explosive will be the greater as its density increases, that is, the greater the weight 
for the same volume ; and for guncotton, for example, the effect will be the greater for 
the same volume, the more it is compressed. Thus the relative specific gravities of 
different explosives are of importance, and in fact fulminate of mercury, which has a high 
specific gravity (five times that of ordinary powder and three times that of nitroglycerine), 
has a maximum rapidity of reaction and is the most powerful detonator, being capable of 
exerting a force of about 27,000 kilos per square centimetre (atmospheres), this being 
about treble that given by any other known explosive. 

In practice, pressures higher than any imaginable may be attained when the volume 
occupied by a given weight of explosive in a closed vessel is less than the critical volume of 
the gas developed, since this critical volume (vol. i, p. 28) cannot be diminished by any 
pressure, however great. If we term charging density the ratio between the weight of the 
explosive in grammes and the volume in cubic centimetres occupied by it in absolutely 
filling its envelope (as though it were liquid or fused), this charging density corresponds 
with the specific gravity of the explosive ; if this density equals or exceeds the 

reciprocal of the limiting volume ( - I into which the gases developed (critical volume) 

\v' 

can be compressed, the pressure attained will be infinitely great and will rupture any 
enclosing vessel, no matter how resistant it may be. The reciprocal of the critical volume 
of the gases produced in the explosion is termed the critical specific volume (or limiting 
density), and comparison of this with the density of charge leads to consequences of practical 
importance. 

Limiting density Specific gravity of 

of the gases the explosive 

Black powder . . . .2-05 .. 1-75 

Nitroglycerine . . .1-40 . . 1-60 

Powdered guncotton . . . 1-16 .. 1-20 

Picric acid . . . .1-14 .. 1-80 

Fulminate of mercury . .3-18 . . 4-42 

.Thus, black powder has a charging density (or specific^gravity) of 1-75 to 1-82, which 
does not reach the limiting density, so that even if it is exploded in its own volume it does 
not break the envelope if the latter is strong enough to withstand the pressure developed, 
namely, about 29,000 kilos per square centimetre. For granular powder, the density of 
which is 1 , the pressure is only 6000 kilos. The real density (specific gravity) of compressed 
guncotton is 1 -2, that of nitroglycerine 1 -6, and that of picric acid 1 -8, all of these being 




VELOCITY OF EXPLOSION 219 

superior to the limiting densities of the corresponding gases ; so that when they explode 
in their own volume, all of these explosives burst the most resistant envelope, and, in such 
cases, the velocity of the explosive wave becomes infinitely great. Fulminate of mercury, 
although it has the high limiting density 3-18 (owing to the low critical volume, v), has a 
specific gravity of 4-42 (to which the density of charge approximates) and behaves like 
nitroglycerine, &c. 

As it is difficult to calculate a priori the pressures exerted by explosives, it is preferable 
to determine them relatively by measuring certain effects of the ga?es at the instant of 
explosion ; this is done, for instance, by observing the crushing or deformation of small 
cylinders of copper or lead, which are termed crushers (Fig. 179). 

The total pressure depends on the character of the explosive and on the nature of the 
explosion (see later), but more especially on the density of charge. 

The specific pressure of an explosive is a constant (a), given by the ratio of the pressure 

P 

(p) to the corresponding density of charge (d) of the explosive itself : a = . This specific 

a 

pressure a is characteristic of any explosive and expresses the pressure developed ~by unit 
weight (1 grm.) of an explosive in unit volume. The specific pressure is not always the 
maximum pressure that can be exerted, this depending, 
as we have seen, on the charging density in its relation 
to the critical volume. 

Velocity of reaction. The duration of the explosion is 
of great importance, since on it depends the greater or FIG. 179. 

less utility of the explosive for different purposes. The 

more rapid the explosion the better is the heat developed utilised, so that this can be 
used almost entirely in heating and expanding the gases and so increasing the pressure 
considerably. If, however, the reaction is slow, a large portion of the heat is dissipated 
by radiation and conduction. 

Explosives with an extremely rapid reaction produce special effects, as they shatter 
the envelope or rock in immediate contact with the explosive into minute fragments 
an effect often not desired. These are termed shattering or detonating explosives and their 
properties are utilised in certain cases, as, for example, where a small cavity is to be made 
in a rock so that a large quantity of a progressive explosive may be subsequently introduced. 

If the reaction, although rapid, is not instantaneous, the explosion produces other 
effects, for instance, the cleaving of large stones or rocks and the projection of fragments 
nearer to the exolosive ; this progressive or rending action is the effect usually desired 
by miners. 

According as the gasification takes place more or less instantaneously (and the one or 
the other effect can be obtained with the same substance by adding inert materials to, say, 
dynamite, or mixing paraffin with guncotton), explosives are more or less shattering. 
Thus, panclastite is more shattering than guncotton, the latter more than dynamite, 
and this more than smokeless powder, which is a progressive explosive. 

Many substances explode only with detonators (of fulminate of mercury) and the 
cause of the explosion in such cases is not only the high temperature produced by the 
explosion of the detonator, but more especially the great immediate pressure resulting 
from the instantaneous production of gas, this pressure and the sudden shock provoking 
the decomposition of the molecules of the explosive (Berthelot, Abel, Vieille). The 
duration of explosion or of gasification of the detonator is 500 times less than that of the 
explosive material, and the greater relative amount of heat developed in "a certain time by 
detonators explains their greater shattering power compared with that of progressive 
. explosives. The most highly shattering materials are : fulminate of mercury, panclastite, 
compressed guncotton, and nitroglycerine. The duration of reaction for detonators 
is only about T ^ of a second, the extraordinary effect of these explosives being due to 
the enormous amount of energy developed (1600 Cals. for nitroglycerine) in this short time 
and in the small space containing them. 1 

1 The velocity of combustion (or of deflaaratron) is sharply distinguished from the velocity of the explosive 
reaction and is made use of it in certain cases, e.g. in the throwing of projectiles (expansive and progressive action)j 
The velocity of combustion of explosives depends on, and increases with increase of, the pressure at which they 
decompose. Another factor influencing the mode of combustion of explosives is the maximum velocity with 
which the pressure develops. 

The exponent of the power of the pressure, which admits < f passing from one value to the other in the increase 




220 ORGANIC CHEMISTRY 

As has been already stated, the shattering effect of a substance is rendered evident by 
exploding a few grammes of it on a cylinder of metal (crusher) and the actions of different 
explosives are compared by means of these deformed and disfigured crushers. Fig. 180 B 
shows a leaden cylinder before the explosion, whilst A shows the same cylinder after 10 grms. 
of dynamite (a progressive explosive) have been exploded on it and C the result of the 
explosion of 10 grms. of panclastite (from nitrotoluene). 

One and the same explosive substance may be made to give either a shattering or a 
progressive effect by varying the velocity of the reaction, this usually depending on the 
power of the initial shock which causes the explosion. The more powerful the initial shock 
the greater is the amount of kinetic energy transformed into heat and hence the higher 
the temperature developed ; therefore, also, the greater is the pressure of the resultant 
gases and the more rapid and powerful the effect of the explosive. The effects vary 
considerably with the manner in which the explosion is induced ; thus, if a flame is brought 
near to non-compressed guncotton, the latter burns rapidly but does not explode ; whilst 
if it is compressed and subjected to the action of a cap (detonator) of fulminate of mercury, 

a real and very powerful ex- 
plosion occurs ; similar pheno- 
mena are observed with nitro- 
glycerine and dynamite. 1 

DETERMINATION OF 
THE EXPLOSION. In order 
to induce the explosive re- 
action of a substance, it is 
sufficient to bring it at a single 
point to a certain initial decom- 
A position temperature (by percus- 

FIG. 180. sion, detonation, &c.), the sharp 

decomposition at this point then 

producing a new shock which heats the neighbouring points to the decomposition 
temperature, and so on, the explosion being thus communicated to the whole mass by a 
true explosive wave, which is enormously more rapid than simple burning. From this will 
be understood the great importance of detonators, which do not serve merely for ignition ; 
and the difference will also be apparent between an ordinary explosion by ignition and 
percussion and that induced by fulminate of mercury detonators. 

When the phenomenon of explosion is studied more closely, it becomes evident that 
the gases produced at the point of ignition tend to expand and hence to diminish the 
pressure at that point and also the rapidity of explosion, but if this initial expansion 
is impeded the pressure and hence the velocity of decomposition increase rapidly. In 
practice miners obtain this effect by filling the cavity containing the explosive with a 

of the pressure, is called the modulus of progressirity, and serves to characterise the various explosives. Thus, 
this modulus varies from 1-25 to 1-50 for black powders and from 1-86 to 1-87 for smokeless powders, whilst that 
of picric acid is 2-82 and that of "Earner's explosive (12 per cent, of dinitronaphthalene -f 88 per cent, of ammonium 
nitrate) 3-25. As will hence be seen, these last two explosives have the dangerous property of furnishing accidental 
superpressures, owing to undulatory phenomena which always accompany the combustion of substances in- 
flammable with difficulty. In smokeless powders, the moderate progressivity compared with the great power 
constitutes a valuable safeguard in their use in firearms ; in this they are surpassed only by black powders, which 
are, however, much less powerful. 

1 The percussive force (kinetic energy) of an explosive serves best to establish the shattering power and is calcu- 
lated by C. E. Bichel by means of the formula -, where m denotes the mass of the gases formed in the explosion, 

or the weight of the explosive, divided by 9-81 and v is the velocity of detonation (i.e. the time elapsing from the 
beginning of the explosion to its completion throughout the whole mass). For 1 kilo of an explosive gelatine 
(92 per cent, of nitroglycerine and 8 per cent, of collodion cotton) with the charging density, 1-63, Bichel gives 
a velocity of detonation of 7700 metres per second, so that the percussive force in absolute units will be : 
1 X 7700 2 
"9^1 x 2 = 3>021 ' 916 kilogram-metre-seconds ; for black powder (with a charging density 1-04) exploded under 

the same conditions in a closed vessel with a detonating cap, the velocity of detonation is 300 metres per second, 

1 x 300 
so that 9 gl x 2 = 4587 kilogram-metre-seconds ; for kieselguhr dynamite (35 per cent, nitroglycerine) the velocity 

of detonation is 6818, and hence the percussive force, 2,369,272 kilogram-metres per second ; for a gdatine-dynamite 
(63-5 per cent. 1 nitroglycerine, 1-5 per cent, collodion cotton, 27 per cent, sodium nitrate, 8 per cent, wood meal), 
with a charging density of 1 67, the velocity of detonation is 7000 and the percussive force 2,497,452 ; for trinitro- 
toluene, with a [charging density of 1-55, the velocity was 7618, and the percussive force 2,957,896 ; guncotton, 
with a charging density of 1-25, had a velocity of 6383, the percussive force being 2,076,589 ; and picric acid, with 
a charging density of 1-55, gave the velocity of detonation 8183, and the percussive force 3,412,920 'kilogram- 
metre-seconds. 



EXPLOSION BY INFLUENCE 221 

tamping of earth or stone. The same end may also be attained by increasing considerably 
the mass of the explosive and the surface of ignition, and this explains why certain sub- 
stances burn, without exploding, in small quantities (guncotton, nitroglycerine, &c.), or 
when the ignition is confined to a limited area, whilst a powerful explosion may occur 
when a large quantity of explosive is used or when it is surrounded by a source of considerable 
heat. 

For shattering explosives (e.g. fulminate of mercury) no tamping is used, since the 
reaction is so rapid that the atmospheric pressure, that is, the air itself with its inertia, 
is sufficient to maintain the pressure of the gases. Even fulminate of mercury, if ignition 
is effected by an electric contact (which heats a platinum wire to redness) and under an 
evacuated bell-jar, burns without exploding, thus confirming the tamping action of the 
air in the case of detonators and even of ordinary explosives ; in fact, if a roll of 
dynamite is exploded on a bridge, the latter is cut in two owing to the tamping action 
of the air. 

The explosive, wave produced in the explosion of gaseous mixtures and of liquids and 
solids is only slightly related to waves of sound. The latter is transmitted from crest to crest 
with but little kinetic energy, with a small excess of pressure and with a velocity depending 
only on the nature of the medium in which it is propagated and of equal magnitude for all 
kinds of vibrations. The explosive wave, on the contrary, propagates the chemical 
transformation through the mass of the explosive substance, communicating from point 
to point of the decomposing system an enormous amount of potential energy and a great 
excess of pressure. The sound-wave is propagated in a mixture of hydrogen and oxygen 
with a velocity of 514 metres per second at 0, but the velocity of the explosive wave in the 
same mixture (exploded at a point) is 2841 metres. 

With guncotton, the velocity of this wave varies from 3800 to 5400 metres per second 
according to the compression ; with nitroglycerine it is 1300, with dynamite 2700, with picric 
acid 6500, and with nitromannitol 7700 metres per second. This velocity depends only 
on the nature of the explosive and not on the pressure, but it varies to some extent with 
the nature of the envelope. For instance, in a rubber tube having a thickness of 3-5 mm. 
and an internal diameter of 5 mm. and covered with cloth, ethyl nitrate gives a velocity 
of 1616 metres ; whilst in glass tubes of various diameters and thicknesses the value is 
1890 to 2480 metres. The propagation of the explosive wave bears no relation to that 
of ordinary combustion (which is much slower). The former occurs when the inflamed 
gaseous molecules acquire the maximum velocity or energy of translation, i.e. act with 
the whole of the heat developed in the chemical reaction. 

Explosion by Influence. If a long row of dynamite cartridges are arranged on a flat 
solid at distances of 30 cm. or on a metal disc at a distance of 70 cm., explosion of the first 
with a fulminate cap results in the rapid and successive explosion of the remaining ones 
simply by influence and without the need of detonators or fuses. Air does not conduct 
the wave of explosive influence as well as solids, and if the cartridges are suspended in the 
air by wires such explosion by influence does not occur. Water conducts the explosive 
wave to a certain distance, but the influence gradually diminishes with increasing distance 
from the centre of explosion (there have been cases in which the shock of a large charge of 
guncotton has exploded neighbouring torpedoes ; to avoid these inconveniences, so-called 
safety explosives are now used). 

These explosive waves are first propagated through the explosive itself, not by a single 
shock which would gradually weaken as it advanced but by a very rapid series of such 
shocks produced by the propagation of the explosion from point to point of the whole mass 
of the explosive, the kinetic energy being thus regenerated along the whole course of the 
wave in the exploding substance. 

An explosive wave is thus distinguished from an ordinary sound-wave by the fact 
that the latter becomes enfeebled as it advances, whilst the former is characterised by the 
uniformity of the energy transmitted from point to point by a series of numerous and 
successive explosions throughout the exploding mass. Only the last of these explosions 
is transmitted with its energy to the surrounding air and to the matter on which the 
explosive rests, and, since it is no longer reinforced (by other shocks), it weakens as it becomes 
more remote. Hence explosion by influence is not due to the fact that the distant explosive 
transmits or propagates the explosive wave through its own mass, but is owing to the arrest 
and transformation, at the point of impact, of the mechanical energy it being capable 



222 ORGANIC CHEMISTRY 

of similar (but not all) waves into heat energy, able to cause decomposition and explosion 
of the substance itself. 

The effects of large charges of dynamite (25 to 1000 kilos) when freely exploded are 
dangerous to buildings and to life for a distance of 500 metres and are felt as far away as 
3 kilometres (L. Thomas, 1904). 

CLASSIFICATION OF EXPLOSIVES. Explosives are to-day so numerous and are 
prepared from such different mixtures and serve such a variety of purposes that a 
rigorous or rational classification is difficult or impossible. Also with a large number 
of classes there would be many substances which might belong to more than one of 
them. 

It will hence be preferable to limit ourselves to a description of the various explosives 
without any prearranged classification. They will be taken in the following order : (1) 
Dynamites with a basis of nitroglycerine; (2) Nitrocellulose ; (3) Various smokeless powders ; 
(4) Picrate powders ; (5) Explosives of the Sprengel type (the components are explosive only 
when mixed) ; (6) Sundry explosives ; (7) Black nitrate and other powders ; (8) Chlorate and 
Perchlorate powders. 

NITROGLYCERINES 

This name is given improperly to nitric esters of glycerine since they do not contain 
true nitro-groups (N0 2 ) united directly with carbon as is often the case in benzene deriva- 
tives. On the contrary, the union is effected through an intermediate oxygen atom, so that 
these compounds should rather be called nitrates of glycerine. 

Being a trihydric alcohol, glycerine can form three such compounds, the only one known 
until quite recently being trinitroglycerine containing 18-5 per cent, of nitrogen and having 
very considerable industrial importance. 

In 1903, Mikolajczak prepared also pure DINITROGLYCERINE, C 3 H 5 .OH(ONO 2 ) 2 , 
containing 15-4 per cent, of nitrogen, and he proposed to use it as an explosive, as it 
possesses almost all the ballistic advantages of trinitroglycerine and is not easily frozen ; 
it is, however, very hygroscopic and readily soluble in water and in acids. 

Dinitroglycerine is prepared by nitrating 100 parts of glycerine with 400 parts of nitric 
sulphuric mixture containing 8 to 12 per cent. H 2 O, 60 to 70 per cent. H 2 S0 4 , and 15 to 32 per 
cent. HNO 3 ; at the end of the reaction, the mass is poured into an equal volume of water, 
and the acid neutralised with calcium carbonate, when the dinitroglycerine separates as a 
dense, floating oil. During the reaction, the temperature is maintained at 18 to 20 
by cooling with ice. Dinitroglycerine is also formed by dissolving trinitroglycerine in sul- 
phuric acid and then diluting the solution with a little water. In whatever way it is pre- 
pared (e.g. by treating 1 part of glycerine with 2 parts of sulphuric acid, separating by means 
of lime the glycerinedisulphuric acid formed and treating this with nitric acid, as proposed 
by Escales and Novak, 1906), a mixture of the two possible isomerides is always obtained : 
dinitroglycerine K (i.e. ay-), N0 3 -CH 2 -CH(OH)-CH 2 -N0 3 , and dinitroglycerine F (i.e. 
a (3-), NO 3 CH 2 CH(NO 3 ) CH 2 . OH, which was studied by W. Will (1908). The mixture 
forms an almost colourless, faintly yellow oil, sp. gr. 1-47 at 15, which freezes at below 
30 to a glassy mass, this distilling almost undecomposed at 146 under reduced pressure 
(15 mm.) ; at 15 it is soluble to the extent of 8 per cent, in water and at 50 to the extent 
of 10 per cent. In dilute sulphuric or nitric acid it dissolves in all proportions and by 
sulphuric acid (up to 70 per cent.) it is transformed into mononitroglycerine and then into 
glycerine. It is very hygroscopic and, when dry, dissolves or gelatinises nitrocellulose 
(guncotton or collodion-cotton) very well. The two isomerides can be separated by taking 
advantage of the fact that, in the air, the F compound absorbs 3 per cent, of water and is 
transformed into a crystalline hydrate, 3(C 3 H 6 7 N 2 ) + H 2 0, whilst the other remains 
liquid. The J^-form gives a nitrobenzoyl-derivative melting at 81, the corresponding 
compound of the Jf-isomeride melting at 94. In the dry state, the dinitroglycerines 
are as useful for explosives as the trinitro -compound, but when moist they are much 
inferior. A mixture of 50 per cent, dinitro- and 50 per cent, trinitro -glycerine freezes 
below 20. 

Of MONONITROGLYCERINE, C 3 H 5 (OH) 2 .NO 3) the pure a- and /3-isomerides are 
known (W. Will, 1908). These are not true explosives and dissolve to the extent of 70 per 
cent, in water. The n -compound melts at 58 and boils at 155 to 160 under 15 mm, 
pressure. 



NITROGLYCERINE 223 

Nitrochlorhydrin, C 3 H 5 C1(NO 3 ) 2 , and Tetranitrodiglycerine (see p. 184) have also 
been proposed as non-congealing explosives, but better still for this purpose are the 
nitroacetins (V. Vender) (see later). 1 

CH 2 O-NO 2 

TRINITROGLYCERINE, CHO-N0 2 or C 3 H 5 (O.N0 2 ) 3 . 

CH 2 O.NO 2 

This was discovered in 1846 by Ascanio Sobrero, 2 who called it Pyroglycerine and 
established its explosive properties but regarded its industrial manufacture as too dangerous. 
Its chemical composition was determined by Williamson in 1854. At first it was used 
only in small doses as a medicine, owirg to its marked power of inducing dilatation of the 
blood-vessels. Later, after various unavailing attempts, Alfred Nobel succeeded in applying 
it industrially, and in 1863 established two nitroglycerine factories in Sweden, these rapidly 
prospering owing to the great demands of various nations for this powerful explosive. 
Nevertheless, owing to the neglect of precautions by consumers in the handling of nitro- 
glycerine, various terrible explosions occurred which almost resulted in the abandonment 
and prohibition of this substance. Fortunately just at this time Nobel discovered a very 
happy solution of the problem which completely eliminated this danger, by mixing the 
nitroglycerine with inert substances (kieselguhr or infusorial earth) and thus obtaining 
dynamite, this being to-day at the head of the great explosives industry. 

PROPERTIES. When pure it is a dense almost colourless or faintly 
yellow liquid of sp. gr. 1-6 at 15, and when it freezes its density increases by 
almost one-tenth, it is odourless and has a sweetish, burning taste. It is 
almost insoluble in water (0-16 to 0-20 per cent, being dissolved at 15), is 
not hygroscopic, and dissolves easily in concentrated alcohol, ether, benzene, 
chloroform, glacial acetic acid, toluene, nitrobenzene, acetone, olive oil, and 
concentrated sulphuric acid, and to a less extent in nitric acid and still less in 
hydrochloric acid ; it is, however, insoluble in carbon disulphide, glycerine, 
petroleum, vaseline, turpentine, benzine, and carbon tetrachloride. In solu- 
tion it will not explode. It evaporates spontaneously and in very small 
quantities even at 50, and if gradually heated to 109 it begins to decompose 
with evolution of brown nitrous vapours. 

Its specific heat is 0-356, and its heat of solidification 23 to 24 Cals. 

Dinitromonochlorhydrin is obtained, according to F. Roewer (1906), by nitrating the monochlorhydrin in 
the same manner as glycerine is nitrated (see later), and is then quickly separated from the top of the nitric-sulphuric 
acid mixture as an oil which is easily rendered stable by washing with water and soda. It forms a faintly yellow, 
mobile oil of aromatic odour, sp. gr. 1-541 at 15, soluble in alcohol, ether, acetone, or chloroform, but insoluble 
in water and in acids. At 180 it gives yellow vapours, and at 190 boils without detonation or deflagration, 
and with only slight decomposition ; under a pressure of 15 mm. it distils unchanged at 121 to 123 as an almost 
colourless oil. It is much more stable towards pressure than nitroglycerine, although possessing almost the same 
explosive properties. It does not freeze even at 30 and is not hygroscopic. It dissolves nitrocellulose, forming 
explosive gelatine, and mixes readily with nitroglycerine, giving non-congealing dynamites (with 5 to 20 per cent, 
of nitrochlorhydrin, Ger. Pat. 183,400), these being prepared by nitrating directly -a mixture of glycerine and 
chlorhydrin. In order to avoid the inconvenient effects on miners of the hydrochloric acid formed in the explosion 
of nitrochlorhydrin, potassium nitrate is added ; during the explosion this is transformed into potassium carbonate, 
which neutralises the acid. 

Dinitroacetylglycenne, C 3 H 6 (ONO 2 ) 2 (OCOCH 8 ), is obtained by nitrating the monoacetin in the same 
apparatus as is used for nitroglycerine, but using an acid mixture containing a preponderance of nitric acid, e.g. 
65 per cent. HNO, and 35 per cent. H-jSO,. The dinitroacetylglycerine being somewhat soluble in water, it is 
lost to some extent during the washing. It is a yellowish oil, sp. gr. 1-45 at 15, and is soluble in alcohol, acetone, 
ether, nitroglycerine, or nitric acid, and almost or quite insoluble in water, benzene, or carbon disulphide. It 
contains 12-5 per cent, of nitrogen and with double its weight of nitroglycerine gives a mixture with 16-5 per cent, of 
nitrogen, which has a lower freezing-point (below 20) than any other mixture of these substances. It serves 
well for preparing non-congealing dynamites, and as it dissolves nitrocellulose easily it can be used for gelatinising 
smokeless powders. 

Uinitroformylglycerine, C 3 H 6 (ONO 2 ) Z (O- CHO), is prepared in a similar manner to the preceding com- 
pound, or, together with nitroglycerine, by nitrating the product obtained by heating 2 parts of glycerine with 
1 part of oxalic acid for 20 hours at 140. Nitroformin and nitroacetin have explosive powers rather inferior 
to that of nitroglycerine. 

1 Ascanio Sobrero was born at Casalmonferrato on October 12, 1812. He first studied medicine and then 
chemistry. In 1840 he went to complete his chemical studies in the laboratory of the celebrated Pelouze at Paris, 
where he stayed two years, and in 1843 he worked in Liebig's laboratory at Giessen. In 1845 he became Professor 
of Applied Chemistry at Turin, where he taught until 1883. He died on May 26, 1888, after a modest life, during 
which he filled various honorary social positions. It was always his aim that science should not be made a pretext 
or means of dishonorable undertakings or of business speculations. 



224 ORGANIC CHEMISTRY 

At a red heat it evaporates without decomposing, but if it begins to boil 
vigorously during the heating, there is danger of explosion. According to 
Champion, pure nitroglycerine in small quantities boils, giving yellow vapours, 
at 185, evaporates slowly at 194, and rapidly at 200, burns quickly at 218 
and detonates with difficulty at 241, violently at 257, feebly at 267, and 
feebly with flame at 287 (being in the spheroidal state). 

When heated in small quantities in the Bunsen flame, it burns without 
exploding, and if spread in a thin layer on paper it ignites with difficulty and 
burns only partially. Explosion of nitroglycerine can be induced either by 
violent percussion at a temperature of 250, or by energetic detonation (e.g. 
by explosion of fulminate of mercury). 

Nitroglycerine may be easily supercooled below its solidifying point. 
Kast (1906) showed that nitroglycerine represents a case of monotropic allo- 
tropy (see also vol. i, p. 191), i.e. it has two freezing-points, + 12 and + 13-5, 
corresponding with different crystalline forms. 1 

When frozen, nitroglycerine explodes with more difficulty than in the 
liquid form. Pure nitroglycerine will not redden blue litmus paper or turn 
starch paste and potassium iodide blue, unless it contains free acids or nitrous 
compounds due to partial decomposition. 

Impure nitroglycerine readily decomposes and may explode spontaneously, whilst in 
the pure state it keeps indefinitely. A sample of nitroglycerine (200 grms.) prepared by 
Sobrero in 1847 is still kept under water in the Nobel factory at Avigliana. 

When decomposing, nitroglycerine turns green owing to the formation of N 2 and N 2 3 ; 
C0 2 , CO, H 2 O, N, and (see also p. 216) are also successively formed. In exploding, 
1 litre of nitroglycerine produces 1298 litres of gas, which, at the temperature of explosion, 
occupies a space of 10,400 litres. 

L In large doses nitroglycerine is poisonous and its vapour causes headache (especially 
at the back of the head), giddiness, and vomiting. These effects are produced even by 
working with or simply touching nitroglycerine and are cured by means of cold compresses 
on the head, by breathing fresh, pure air, and by drinking coffee and taking suitable 
doses of morphine acetate. 

Workmen who handle the nitroglycerine paste during the manufacture of the various 
dynamites become habituated to it in two or three days and afterwards feel no ill -effects. 
Nitroglycerine is moderately easily decomposed by alcoholic potassium hydroxide (with 
separation of glycerine), and, when necessary, this reaction is employed to destroy and 
render harmless small quantities of nitroglycerine ; similarly benches or floors on which 
nitroglycerine is spilt are washed with caustic alkali solutions : 

C 3 H 6 (ON0 2 ) 3 + 5KOH = KNO 3 + 2KNO 2 + CH 3 .COOK + H-COOK + 3H 2 ; 

a little ammonia is also formed. With reducing agents it gives ammonia and glycerine, 
whilst with concentrated sulphuric acid it yields nitric acid and glycerinsulphuric acid. 

1 Both nitroglycerine and dynamites and smokeless powders prepared from it are liable to solidify, and although 
they are then more stable the thawing is accompanied by danger, and when not carried out with great precautions 
has often led to fatal explosions, these being sometimes caused by the mere rubbing of the crystals. Indications 
will be given later of the precautions taken in magazines to prevent freezing, and mention may be made here of the 
attempts which have been made to render nitroglycerine non-congealable. As early as 1895 it was proposed to add 
nitrobenzene to nitroglycerine to lower the freezing-point, and later the use of orthonitrotoluene was suggested ; 
but the practical results were not very satisfactory in either case, the depression of the freezing-point being very 
small. Substances were required which were almost as explosive as trinitroglycerine, and were insoluble in water 
and stable on heating, and, in addition, were good solvents for nitrocelluloses (for making smokeless powders). 
These conditions were well satisfied by the nitroformins and nitroacetins tested by Nobel as early as 1875 but 
rendered practically useful in 1906 by V. Vender. The best results are given by dinitromonoacetin which is obtained 
from the monoacetin of glycerine prepared by the ordinary method used for esterifying alcohols with acids (see 
later, Esters). Forty parts of the monoacetin are introduced slowly into a mixture of 100 parts of nitric acid (sp. gr. 
1-530) and 25 parts of oleum or Nordhausen sulphuric acid (containing 25 per cent, of free SO 3 , see vol. i, p. 275), the 
mass being cooled so that the temperature does not exceed 25. The whole is then poured into water and washed 
with cold and afterwards with hot (70) dilute soda. By this means an oil is obtained having sp. gr. 1-45 and 
containing 12-5 per cent, of nitrogen ; it is insoluble in water, carbon disulphide or benzene, but dissolves un- 
changed in nitric acid, nitroglycerine, methyl or ethyl alcohol, acetone, acetins, &c. Even in the cold, it has 
considerable solvent and gelatinising power for collodion-cotton and guncotton (with 13-4 per cent, of nitrogen) 
and the resulting explosive gelatines do not freeze even at 20. Naukhorf (1908) has proposed the addition of 
nitromethane or nitroethane to dynamite to lower its freezing-point, and at the present time liquid dinitrotoluene is 
largely used for the same purpose. 



MANUFACTURE OF NITROGLYCERINE 225 

Characteristic Reactions. According to Weber, small quantities of nitroglycerine are 
detected by treatment with aniline and concentrated sulphuric acid : a reddish purple 
coloration is obtained which turns green on addition of water. To establish the purity 
and keeping qualities of nitroglycerine, the nitrogen is determined and Abel's heat test 
carried out (see later, Testing of Explosives) ; if it is satisfactory, 2 c.c. of it withstands 
20 to 30 minutes' heating at 82 without giving sufficient nitrous vapours to be detectable 
by means of starch and potassium iodide paper. 

This reaction is, however, given by nitroglycerine* kept for a few days at a temperature 
exceeding 45, or for a long time below this temperature. 

PREPARATION. It is obtained by the action of a mixture of nitric and 
sulphuric acids on glycerine : 

C 3 H 5 (OH) 3 + 3HN0 3 = 3H 2 + C 3 H 5 (N0 3 ) 3 . 

The mono- and dinitro-compounds are probably formed as intermediate 
products of this reaction. 

The presence of sulphuric acid, which plays no apparent part in the change, 
is usually regarded as being necessary to maintain the nitric acid at a high 
concentration, i.e. to decompose the hydrates formed by nitric acid with the 
water from the reaction (KN0 3 , H 2 HN0 3 , 3H 2 0) and so regenerate mono- 
hydrated nitric acid, which acts on the glycerine (Kullgren, 1908). If the func- 
tion of the sulphuric acid were merely to fix the water, phosphoric acid could 
be used in its place ; but if this is done no nitroglycerine is obtained. 

The excess of the nitric-sulphuric mixture which is always used helps to 
produce a moderately complete separation of the nitroglycerine, which has a 
slightly lower density, so that it is possible to recover the acids employed. 
Although nitroglycerine is soluble in sulphuric or nitric acid alone, it does not 
dissolve in the mixed acids. But if one of the two acids is in large excess, a con- 
siderable amount of nitroglycerine remains in solution and is lost. In the nitra- 
tion, the whole of the glycerine cannot be added at one time, since sufficient 
heat would in that way be developed to produce decomposition and explosion 
of the nitroglycerine instantaneously formed. It is also not convenient to 
reverse the operation, that is, to add the mixed acids gradually to the glycerine, 
the greater density of the latter rendering rapid and homogeneous mixing 
difficult ; it is hence preferable to run the glycerine slowly into the acid mixture 
and to keep the latter continually and thoroughly stirred and cooled. 

MANUFACTURE. The theoretical proportions of the reacting substances 1 would be 
100 parts by weight of glycerine and 205-43 of pure nitric acid, the theoretical yield of 
trinitroglycerine being then 246-74 parts. But on a large scale the whole of the nitric 
acid does not come into immediate contact with the whole of the glycerine, and it is hence 
better to use a slight excess of nitric acid (240 parts or even more) ; the amount of sul- 
phuric acid employed always exceeds that of the nitric acid (about if times). In modern 
factories the following proportions are often used : 100 kilos of glycerine, 240 to 260 kilos 
of nitric acid (98 per cent.), and 340 to 360 kilos of sulphuric acid (96 to 98 per cent.). 

In the best factories, the practical yield is 215 to 232 kilos of nitroglycerine per 100 
of glycerine, but in some cases it amounts to only 205 to 210 kilos. Good yields are obtained 
by cooling the acid mixture during nitration by means of solutions from cooling machines, 
the temperature of reaction being kept down to about 10. 

The low value of the practical compared with the theoretical yield (246-7) is due to the 
fact that towards the end of the reaction there is very little free nitric acid and the last 

1 The prime materials used in the manufacture of trinitroglycerine should be subjected to rigorous control ; 
the glycerine should be pure and distilled and should satisfy the requirements indicated on p. 188. The nitric acid 
should have a specific gravity of 1-500 (48 B6. or about 95 per cent. HNO 3 ) and should not contain more than 
1 per cent, of nitrous acid, i.e. it should not be yellow, as otherwise an increased amount of heat is evolved 
during nitration and the yield is lowered. The sulphuric acid should be pure, with a sp. gr. of 1-8405 (i.e. at 
least 96 per cent. H 2 SO 4 ) and acid containing more than 0-1 per cent, of arsenic should be avoided ; lead and 
iron should also be absent as they might lead to reduction. When nitrations are carried out with nitric-sulphuric 
acids almost free from water (1 to 2 per cent.) the sulphuric acid is replaeed by oleum or Nordhausen acid (see 
vol. i, p. 275), i.e. acid containing 20 per cent, or more of dissolved sulphur trioxide. 

15 



226 



ORGANIC CHEMISTRY 



portions of glycerine added are nitrated only with difficulty and hence remain dissolved in 
the sulphuric acid. 

The mixture of nitric and sulphuric acids, which is prepared separately, is ir.ade by 
pouring the sulphuric acid slowly into the nitric acid (not vice versa) in an iron vessel, 
the mixture being kept well cooled and stirred. With this procedure there is no danger 
of the acid spurting, and no production of nitrous fumes, since the development of heat 
is gradual. This mixture is forced by means of elevators (Montejus) or pulsometers 
working with compressed air (vol. i, p. 264) into tanks which feed the leaden apparatus in 
which the glycerine is nitrated. 

During recent years, many vitriol and explosives works have made considerable use 
of Kuhlmann emulsors (or Mammoth pumps) for raising concentrated acids, which are 
rendered lighter by emulsification with air (see illustration, vol. i, p. 265). 

The leaden nitration apparatus is shown in Fig. 
181. It is surrounded by a wooden jacket inside 
which water circulates. Inside the vessel are peri- 
pheral leaden coils through which large quantities of 
cold water are continually passed by means of the 
two tubes D. The tubes C lead dry compressed air 
to the bottom of the liquid, which is thus kept 
thoroughly mixed. The tube F serves as exit for 
the air, and for any nitrous vapours which may be 
evolved and may be observed through the window, 
/ ; these vapours are recovered in small condensation 
towers sprinkled with a little water. The cold acid 
mixture is first introduced through the pipe G. The 
glycerine, at a temperature of 20 to 25 (if colder it 
would be too viscous), is measured in the reservoir, 
M, and is passed, by means of compressed air supplied 
through O, slowly into the tube H, and thence into 
a perforated circular pipe at the bottom of the appa- 
ratus. Two thermometers, E, show the temperature 
of the reacting mass at any moment. 

The bottom of the apparatus is slightly inclined 
and at the lowest part is inserted a large stoneware 
tap, K, with an ebonite screw containing an aperture 
of at least 5 cm. It is convenient to have two of 
these taps so that, in case of danger, the whole of 
the mass may be rapidly discharged into a vessel of 
water underneath (drowning of the nitroglycerine). 
In such an apparatus, the same quantity of nitro- 
glycerine is produced each time and the treatment 
of 100 kilos of glycerine requires less than half an 
hour. 1 In America as much as 2000 kilos of 

glycerine are worked at one time in open vessels provided with stirrers, but the risk, 
in case of explosion, is greatly increased. At the conclusion of the operation the nitro- 
glycerine (sp. gr. L-6) floats on the acids (sp. gr. 1-7) and is separated by means of a 
suitable decanting apparatus (Fig. 182) to the bottom of which the whole mass is passed 
through the tube K. The apparatus consists of a leaden tank with its base sloping towards 

1 The temperature during the reaction should not exceed 25 to 30, and it can be regulated by passing the 
cooling water more or less rapidly through the coils, and, if necessary, through the wooden jacket ; increase of the 
air-current also helps to lower the temperature. Rise of temperature and consequent explosion were at one time 
due principally to the use of impure glycerine, but nowadays it is generally due to slight escape of water from the 
coils. In order to avoid such danger, the apparatus and coils are tested at least once a day, usually in the evening 
when the plant is free ; water under pressure is forced into the coils and jacket and left until the morning, when 
any leak can be detected. Although the apparatus is constructed of vety thick plates, the lead corrodes in time ; 
tests made with aluminium apparatus (proposed by Guttler) have not been very successful. Some works now employ 
more solid vessels of wrought or cast iron, which arc more easily cooled. 

Boutmy and Faucher avoid the dangers of violent reactions by first dissolving, e.g. 100 parts of glycerine in 
320 of sulphuric acid and then pouring the solution into a mixture of 280 parts of nitric and 280 of sulphuric 
acid. After 12 hours the reaction is complete, the yield being 190 per cent., calculated on the weight of the 
glycerine taken. This method did not give good results in England, but lias bei-n applied in France. 

Kurtz increases the yield and accelerates the reaction by emulsifying the glycerine with air and passing it 
under the acid mixture, a more intimate mixture being thus obtained. 




FIG. 181. 



ITROGLYCERINE PLANT 



227 




FIG. 182. 



the centre and supported by a wooden structure ; the cover, C, is raised on wooden 
joists, B. The tube D, with the glass window, E, serves to carry off any gas which may 
be evolved ; a thermometer is inserted into the vessel at t. The tube shown at the bottom 

and in the centre of the appa- 
ratus communicates with two 
or three taps, H, and is also 
fitted with a window, F. 

After half an hour, the nitro- 
glycerine in this vessel separates 
into a distinct layer, as may be 
seen through /. The surface of 
separation of the two layers 
coincides very nearly with the 
tap J ', so that the nitroglycerine 
can be discharged almost" com- 
pletely through the tube J into 
the lead-lined wooden tank, L. 
The acid that remains is dis- 
charged through one of the taps, 
H, it being noted through F when 
a turbid layer appears, as this 
separates the acid from the nitro- 
glycerine and contains various 
nitro -products and certain im- 
purities. 1 

The tap, H, is then closed and this liquid is passed through other taps into suitable 
washing and decanting vessels (see later). The nitroglycerine in L is washed with water 

1 The acid separated from the nitroglycerine and containing about 72 per cent. H 2 SO 4 , 9 per cent. HN0 3 , 
16 per cent. H 2 O, and 3 per cent, of dissolved nitroglycerine, is collected in leaden tanks in which it remains for 
one or two days, during which time a small quantity (about 0-5 per cent.) of nitroglycerine separates at the surface. 
The dangers of this slow separation are some- 
timrs avoided by neglecting the nitroglycerine 
which separates after 4 to 5 hours ; to avoid 
danger in succeeding nitrating operations, a 
large proportion of the nitroglycerine remaining 
dissolved is decomposed by adding cautiously 
4 to 5 per cent, of water so as to raise the tem- 
perature to 35 to 40 and then again mixing 
the mass by means of air (part of the trinitro- 
glycerine is thus transformed into soluble dinitro- 
glyeerine). These recovered acids, which are 
utilised again, are first denitrated in the appa- 
ratus shown in Fig. 183. This consists of a 
cylinder of earthenware or volvic stone filled 
with fragments of silica (quartz) or glass, on to 
which the acid from the tank, D, is sprayed ; a 
current of steam from the cock, a, together with 
a little air are passed upwards through the tower. 
As the temperature rises the organic matters are 
oxidised at the expense of the nitric acid, which 
thus gives oxide of nitrogen, this passing with 
the other nitrous vapours into the tube, H, which 
is supplied with a current of air from the injec- 
tor, //. The mixed vapours are divided between 
a double battery of long vertical earthenware 
pipes, G, where nitric acid of 38 to 40 B6. 
condenses, any vapour escaping being finally 
condensed in a Lunge-Rohrmann tower. 

The sulphuric acid at last reaches the bottom 
of the tower, A, where it collects in the basin, 
E, and thence passes through the leaden cooling 
coil, F. The acid thus obtained is darkened by the impurities present and has a density of about 56 to 58 B6 ; 
it is usually concentrated in cascade apparatus of the Negrier type or in Gaillard towers (see vol. i, p. 269). 
- During recent years, instead of the sulphuric and nitric acids being recovered and concentrated separately, it 
has been found preferable to send the acid mixture after decomposition of the dissolved nitroglycerine (see above) 
directly but carefully into the boilers (already containing the sodium nitrate) in which nitric acid is made. 
Some prefer to revivify the acid mixture, i.e. to bring it up to its original strength by adding the necessary quantities 
of fuming nitric and sulphuric acids, so that it can be used again for the production of fresh quantities of nitro- 
glycerine ; for this purpose, sulphuric acid or oleum is added slowly to the required amount of concentrated nitric 
acid and the mixture then poured into the weak acid. For this process of recovering the weak acids (by which the 
2 ."> percent, or so of nitroglycerine dissolved in the acid is recovered) to be employed, a cheap supply of sulphuric 
anhydride or oleum must be available (oleum at less than 4s. per quintal). 



^ 




FIG. 183. 



228 



ORGANIC CHEMISTRY 



and is then agitated by passing compressed air through the perforated pipe, N, for about 
fifteen minutes ; the nitroglycerine is allowed to settle and the water decanted off by means 
of the upper tap, M. The washing with water is repeated two or three times, all the washing 
water being collected in a single tank. 1 Finally the nitroglycerine is passed into a similar 
vat where it is stabilised, i.e. washed alternately with very dilute soda solution and water 
until the wash -water no longer has an acid reaction towards litmus and the nitroglycerine 
has a feeble alkaline reaction (0-01 of alkalinity, which disappears later). 

In the British Government factory at Waltham Abbey, Nathan, Thomson, and Rintoul 

(Eng. Pats. 15,983, 1901 ; and 
3020, 1903) prepare nitrogly- 
cerine in large leaden vessels 
(a, Fig. 184) with inclined 
bottoms ; in these 300 to 500 
kilos of glycerine are treated 
at one time and at the end 



of the operation, after 50 to 
60 minutes' rest, the acid 
recovered from a preceding 
operation is passed from the 
tank, c, to the bottom of a. 




FIG. 184. 



In this way the nitroglycerine is displaced and caused to discharge through s into the 
washing vessel, e, exit for the vapours being supplied by the tube o. When all the nitro- 
glycerine has been forced out, a little of the acid mixture is drawn off by the pipe i, 2 to 
3 per cent, of water being then slowly added to the remainder, which is mixed meanwhile 
with a current of air. By this means the dissolved nitroglycerine is decomposed and the 
dangers of slow separation in any of the vessels avoided (see preceding Note). 'The acid 
is immediately denitrated, after sufficient has been passed into the tank, c, to displace 
the nitroglycerine of the succeeding operation, b is the tank in which fresh acid is 
mixed, / the vessel for drowning, g that for stabilising, and h the filter for the nitro- 
glycerine, these two being at a considerable distance from e so that the nitroglycerine may 
be conducted to them as soon as it has undergone its initial rough washing. Yields of 
as much as 230 per cent, are obtained with this Nathan -Thomson process. In Italy it 
is used at the Villafranca (Tuscany) dynamite 
factory. 

FILTRATION. The washed nitrogly- 
cerine is carried in hardened rubber or ebonite 
buckets to the filters, which are merely wooden 
frames covered with woollen cloth or felt to 
retain the impurities, scum, gummy matters, 
&c. By covering these cloths with a layer of 
dried salt, the emulsified water can also be 
held back. The cloths rapidly become blocked 
and are frequently renewed. The filtration 
is often, especially in England, effected by 
means of the apparatus shown in Fig. 185. 
This consists of a lead-lined tank, A, with 
inclined base. In the lid is inserted a leaden 
cylinder, G, with a metal gauze bottom on 
which rests a filtering cloth, N, and on this a 
layer of sodium chloride, O, covered by another filtering cloth kept stretched by a leaden 
ring, Q ; the free part of this cloth is folded, stretched, and fixed by a conical leaden 
weight, E. In place of salt, a sponge may be employed to retain the water. In some 
cases complete separation of the water from nitroglycerine is obtained by leaving the 
latter at rest for a couple of days in a tepid place (30) ahd then decanting it ; but there 

1 The wash-waters from all the preceding operations are collected in an inclined lead-lined tank called the 
labyrinth, which is divided into a number of chambers by vertical leaden walls perforated alternately at the top 
and bottom. The wash-waters enter slowly at one end of the tank and traverse a long up-and-down course, 
gradually depositing the emulsified or suspended drops of nitroglycerine before the opposite end of the tank is 
reached. The nitroglycerine collected at the bottom is discharged through suitable taps and added to that in the 
washing apparatus. 




FIG. 185. 



DYNAMITES 229 

is then some risk owing to the prolonged accumulation of large quantities of nitro- 
glycerine, i 

In the working of nitroglycerine, each operation is usually carried out in a separate 
building, that in which the explosive is produced being at a very high elevation, the nitro- 
glycerine then flowing to lower points for the succeeding operations. All these buildings 
are of wood so as to diminish the damage in case of explosion. The floors of the sheds in 
which the nitroglycerine is produced and of those where it is treated in the liquid state are 
covered with sheet-lead with raised edges so that the material may be caught in case of 
breakage. 

Where the nitroglycerine is worked in a pasty state (for dynamites) the flooring is of 
wood free from crevices. 

If nitroglycerine is accidentally spilled, it should be immediately wiped up with 
sponges. 

The channels through which nitroglycerine passes from one shed to another are in the 
form of gutters furnished with removable covers and are fitted with a longitudinal pipe 
through which warm water can be circulated in winter and the danger of freezing avoided. 
A disadvantage attending the use of these channels is that an explosion in one shed is 
propagated along the channels to all the other sheds. So that the precaution is taken of 
disconnecting one section of a channel when not in actual use. In many factories the nitro- 
glycerine is transported in rubber pails (see above). 

The windows of the sheds are smeared with whitening, as the presence of curved parts 
in the naked glass might possibly result in the focusing of light on the explosive material 
and the explosion of the latter. 

USES OF NITROGLYCERINE. Small quantities are sometimes used 
in medicine to induce dilatation of the blood-vessels, but practically the whole 
of the production is used as an explosive. In America it has been long in use 
in the pure state for large mining operations ; Mowbray freezes it and trans- 
ports it in large quantities on trains from the factory to the place of consump- 
tion, as he regards it as less sensitive in the frozen state ; but this view is generally 
contested. It has also been transported without danger in solution in methyl 
or ethyl alcohol, from which it is reprecipitated with water at its destination. 
Almost all the nitroglycerine made is used in the manufacture of various kinds 
of dynamites, dynamite gelatines, explosive gelatines, smokeless powder, &c. 

DYNAMITES. This generic name is given to explosives obtained by 
gelatinising or absorbing nitroglycerine by various other substances. We have 
already mentioned that Alfred Nobel, the father of dynamite, had from 1860 
to 1864 various explosions of nitroglycerine, sometimes of that recovered from 
the alcohol in which it had been transported (see above). In his attempts to 
diminish the dangers of nitroglycerine by diluting it with inert substances, 
Nobel discovered in 1866 that it is absorbed by kieselguhr (infusorial earth) in 
considerable proportions (up to 81 per cent.), and that in this state its power 
is diminished but little, while it can be safely handled and transported. He 
found further that this dynamite is exploded only by means of a fulminate of 
mercury cap. 

Kieselguhr is found in a very pure state in the Liineburg moors, near Unterluss in 
Hanover, and in an inferior quality in Scotland, Norway, and Italy. It consists almost 
exclusively of the siliceous remains of diatoms, and contains also traces of iron and organic 
matter. Its particles are formed of empty tubes perforated in all directions, and it is 
this structure which renders kieselguhr so highly absorbent. Under the microscope, it 
presents the appearance shown in Fig. 186. At the present time kieselguhr dynamite 
has been almost entirely replaced by new types (gums or gelatines) described later. 

If the absorbing substances are inert, like infusorial silica (kieselguhr), sawdust, cellulose, 
&c., they form dynamites with inactive absorbents, which contain about 72 to 75 per cent, 
of nitroglycerine, 24-5 per cent, of kieselguhr, and 0-5 per cent, of soda for the No. 1 quality, 
and less nitroglycerine in the Nos. 2 and 3 qualities. 

But in the new type of dynamite the solid matter consists of active substances, e.g. 
nitrocellulose, which take part in the explosion. These are dynamites with active absorbents, 



230 



ORGANIC CHEMISTRY 



the absorbents or bases being again divided into nitrates or inorganic oxidising bases and 
organic nitro-absnrbents (collodion-cotton, &c.). 

I. MANUFACTURE OF DYNAMITE WITH INACTIVE ABSORBENTS. The 
kieselguhr used must be suitably prepared. It is first spread out in furnace chambers 




TIG. 186. 

and gently heated to eliminate moisture and organic matter, and is then more strongly 
calcined in reverberatory or muffle-furnaces, excessive heating being avoided as it may 
destroy the absorbing properties. It is then ground into fine powder and sieved. The 
flour thus obtained should not contain more than 1 per cent, of moisture and should be 

immediately filled into sacks and consumed the same 
day, as otherwise it might absorb moisture. It consists 
of silica with traces of oxides of iron and aluminium. 

The nitroglycerine is weighed in buckets of hard gutta- 
percha or lacquered compressed wood-pulp and is carefully 
taken to the mixing-house, where it is poured into wooden 
troughs lined with sheet-lead, and containing the absor- 
bent. Skilled workmen then mix the mass rapidly by 
hand ; sometimes rubber gloves are worn, but usually the 
men prefer to do without gloves, as the hands become 
accustomed to the action of the nitroglycerine in two or 
three days. 

It is important to obtain a homogeneous mixture, so . 
that not the least portion of the kieselguhr remains free 
from nitroglycerine. After this hand-mixing the mass is 
rubbed through brass-wire sieves (2 to 3 meshes per centi- 
metre) arranged above lead-lined wooden troughs. The 
dynamite is placed on the sieve with a wooden spatula 
and pressed through with the palm of the hand ; here, 
too, the use of rubber gloves is not popular with the 
operatives. In the troughs the dynamite is in the form 
of fine grains, which should not be too dry or too 
greasy. If too dry, it is passed again through the sieve or mixed with more nitro- 
glycerine, whilst if too greasy it is mixed with a further amount of kieselguhr. It is 
then placed in small portions in iiidiarubber bags or in .wooden boxes lined with sheet- 
zinc and is removed to the building where the cartridges, used especially in mines, are pre- 
pared. Here the dynamite is transformed by simple presses into rolls, 19, 23, or 26 mm. in 
diameter. A very simple press devised by O. Guttmann is shown in Fig. 187. The dyna- 
mite is introduced into the cloth bag, m, and falls into the tube, I, being pressed into this 
by the lignum vitse or ivory piston, p, at the end of the bar, d, which is actuated by the 




FIG. 187. 



COMPOSITIONS OF DYNAMITES 231 

ICVCT, i ; the cylinder of dynamite issuing from the bottom of the tube, Z, is broken by hand 
into definite lengths, which are wrapped in parchment paper or paraffined paper. The 
ordinary length is 10 cm. (discharge cartridges) or 2-5 to 5 cm. (primers). These cartridge 
machines are sometimes worked by pulleys and motors. In some cases the boudineuses 
illustrated later are used. After the dynamite is wrapped up, packets of 2-5 kilos are placed 
in cardboard boxes, which are wrapped and tied round and filled in tens into wooden cases. 
For military purposes the cartridges are put directly into metal boxes with a socket in the 
lid for inserting the detonator. For use under water these metal boxes are sometimes 
used, and sometimes sausage-skins or rubber bags. 

These cartridge buildings are usually small with light walls and roof ; only two or three 
operatives work in each, high earthen banks separating one man from the next so that the 
effects of an explosion may be mitigated. 

In place of kieselguhr various other absorbents are used at the present time, e.g. wood 
meal (cellulose) mixed with inert mineral salts (calcium carbonate, sodium bicar- 
bonate, &c.). 

First in America and then in -Austria fulgurite was prepared with 60 per cent, of nitro- 
glycerine, the remaining 40 per cent, consisting of wheaten flour and magnesium carbonate. 
At Cologne, Miiller prepared a Wetter- dynamite (safety dynamite, for use in mines containing 
firedamp ; see later) by mixing 10 parts of ordinary dynamite with 7 parts of crystalline 
sodium carbonate ; the water-vapour formed on explosion surrounds the flame and the 
explosive gases and thus prevents explosion of the firedamp. Many varieties of these 
dynamites are used to a greater or less extent in practice, e.g. carbodynamite containing 
90 per cent, of nitroglycerine and 10 per cent, of carbonised cork, sebastine, lithoclastite, 
carbonite, &c. 

Properties of Dynamite with Inert Bases. This forms a pasty mass of reddish yellow, 
red, or grey colour according to the quality of the infusorial earth employed ; to ensure 
a uniform colour about 0-25 per cent, of burnt ochre is often added. It is odourless and 
has the sp. gr. 1 -4 and the pasty consistency of wet modelling clay ; the inside of the wrapper 
should show no traces of nitroglycerine (sweating). It is much less sensitive to pressure 
and percussion than nitroglycerine and, in small portions, can be lighted and burned 
without exploding. 

It can, however, be exploded by powerful percussion or detonation, or by red-hot 
metal, or by heating suddenly to a high temperature or for a long time at 70 to 80. 
Dynamite freezes at temperatures below + 8 and then becomes less sensitive ; before 
being used it must be carefully thawed in warming-pans, surrounded by water at a tem- 
perature not exceeding 60 ; it must never be thawed on a heated metal plate. Thawed 
dynamite should be used carefully as a little nitroglycerine exudes during thawing. Most 
of the dynamite made is used as an explosive in mines and for firearms ; for cannon it 
has little use, owing to the danger caused by sweating during the thawing, so that for 
military purposes explosives are used which are safer to transport and not so sensitive to 
shock or to discharge (explosion by sympathy). 

II. DYNAMITES WITH ACTIVE BASES, (a) Pulverulent Dynamites with 
Inorganic Nitrates. Immediately after the discovery of dynamite with a silica base 
came the idea of replacing the inactive substance, which diminished the force of the 
nitroglycerine, by active substances so that the explosive power of the dynamite might 
be increased. 

In America such dynamites are often made with 40 per cent, of nitroglycerine, 45 per 
cent, of sodium nitrate, 14 per cent, of wood-pulp, and 1 per cent, of magnesium carbonate ; 
these dynamites are well suited for mines where no great power but considerable safety is 
required. In Europe mixtures of nitroglycerine, ammonium nitrate, fine sawdust, sodium 
nitrate, carbon, &c., are made ; e.g. 20 per cent, nitroglycerine, 36 per cent, sodium nitrate, 
25 per cent, ammonium nitrate, 18-5 per cent, roasted rye flour, and 0-05 per cent. soda. 

In Austria Trauzl in 1867 prepared a pasty mixture of nitroglycerine with guncotton, 
which was not affected by water and was exploded only by fulminate of mercury detonators. 
This product was not successful, but similar and improved preparations were subsequently 
made. 

About this time Abel in England prepared glyoxiline by soaking defibred guncotton 
and potassium nitrate in nitroglycerine ; this was also unsuccessful. 

(b) Blasting Gelatine and Gelatine Dynamite. Since these contain nitrocellulose, they 



232 

will be mentioned later (see Smokeless Powders), after the manufacture of nitrocellulose 
has been described. 

Statistics of dynamite : see later at the end of the chapter on Explosives. 

NITROCELLULOSE 
(Guncotton or Pyroxyline and Collodion-Cotton) 

This substance should, to be in order, be described later, after cellulose 
(which is a carbohydrate with many alcoholic groups and with a molecular 
formula polymeric with C 6 H 10 5 ) has been studied, but as its properties and uses 
are closely connected with those of explosives, it is considered opportune to 
include it in the present section. 1 

CONSTITUTION OF NITROCELLULOSE. The relation C w H 2w O w of the com- 
ponents of cellulose being expressed by the more simple formula (C 6 H 10 O 6 ) W , it is found that 
the maximum degree of nitration consists in the introduction of three nitric acid residues per 
molecule of C 6 H 10 O 6 , so that guncotton was. given the name trinitrocellulose, and was repre- 
sented by the formula C 6 H 7 5 (N0 2 )3. Since the use of more dilute acids results in the 
combination of a less proportion of nitric acid residues, it is supposed that a mononitro- 
and a dinitro-cellulose are also formed. 

It was found later by Eder that there exist nitrocelluloses with compositions intermediate 
to those of tri- and di-nitrocellulose, and others between the mono- and di-nitro-compounds, 
so that it must be supposed that cellulose has a formula at least double that of the 
simple one given above ; but the mononitrocellulose corresponding with this doubled 
formula, C 12 H 20 10 , i.e. (C 6 H 10 H 5 ) 2 , has not yet been prepared. 

Still later Vieille, by accurate study of the nitrocelluloses prepared with acids of various 
concentrations, succeeded in preparing eight different types of nitrocellulose, this result 
indicating that Eder's formula, which predicted only six, could no longer serve. Vieille 
then proposed for cellulose a formula double that of Eder, i.e. C 24 H 40 20 or (C 6 H 10 5 ) 4 . 
according to which twelve nitrocelluloses are theoretically possible ; eight of these, from 
endeca- to tetra -nitrocellulose have been actually prepared. Mendelejeff, having found 
nitrocelluloses intermediate to or identical with these twelve, but different from those 
studied by Vieille in being soluble in a mixture of alcohol and ether, proposed the doubling 
of Vieille 's formula, so that cellulose becomes C 48 H 80 40 or (C 6 H 10 O 5 ) 8 . To-day, however, 
it is thought that these differences are due to mechanical mixtures of the various nitro- 

1 In 1833 Braconnot observed that when starch or wood is treated, with concentrated nitric acid, a mucilaginous 
solution is obtained which, on addition of water, yields a white powder soluble in a mixture of alcohol and ether ; 
this powder, which burns vigorously, he called xyloidin. In 1838, by subjecting cotton to the same treatment, 
Pelouze obtained a product which exploded on percussion and was indeed nothing but xyloidin ; he recommended 
it as highly suitable for the manufacture of fireworks. In 1845 Schonbein at Basle, and some months later, and 
independently, Bottger at Frankfort discovered that the nitration of cellulose takes place much more easily and 
completely if the cotton is treated with a mixture of concentrated nitric and sulphuric acids. In order to utilise in- 
dustrially the guncotton thus obtained, the two discoverers combined and kept their process secret. After the 
initial difficulty in getting this new explosive taken up in practice, the extraordinary power of guncotton and its 
great advantages over black powder aroused considerable enthusiasm. But scarcely had it come into general use in 
various countries than a number of spontaneous and fatal explosions in guncotton factories and magazines, by 
which whole buildings were razed to the ground, created such a panic that its manufacture was everywhere 
abandoned. The process of nitration was then already known to Knop and Karmarsch, and to others, who 
manufactured guncotton by this simple process. And in 1846 Sobrero made use of the nitric-sulphuric mixture 
for the preparation of nitroglycerine. 

In 1853 the Austrian, Captain von Lenk, ascertained how to render guneotton safe. The Austrian Government 
acquired from Schonbein and Bottger the process of manufacture (at a price stated to be 30,000 florins, or 2500) 
and maintained the secret of avoiding the spontaneous decomposition of guncotton until 1862. Then von Lenk 
communicated the secret to the French and English Governments, and in 1864 patented the process in America. 
Whilst in America the manufacture was undertaken on an enormous scale, in Austria and England it was again 
suspended on account of further terrible explosions in the factories themselves ; these were explained by the 
English workers as due to the insufficient purification of the nitrocellulose by von Lenk. In 1865 Abel discovered 
the method of bestowing absolute safety and keeping qualities on the nitrocellulose. He used first of all the 
process of washing proposed in 1862 by the Englishman J. Tonkin, which consisted simply in complete washing with 
abundant supplies of water ; the nitrated cotton was then defibred or pulped in machines similar to those em- 
ployed in paper factories and the wet pulp subjected to considerable pressure. From that time the manufacture 
extended to all countries, in spite of an English factory being blown up in 1871 (apparently a criminal act), and in 
recent times it has acquired new and increased importance owing to the discovery of smokeless powder. 

The process universally used at the present time in the manufacture of guncotton is that indicated by Abel. 
Before the discovery of smokeless powder, guncotton had limited applications and was not used in mines since, in the 
form in which it was prepared, it had an excessive shattering action, whilst in mines progressive explosives are 
usually required. 



GUNCOTTON 233 

celluloses rather than to separate chemical combinations, and further, that the nitration 
is gradual and leads from the more simple to the more complex forms. 

Nitrocelluloses with more than 12-83 per cent, of nitrogen were at one time regarded 
as being insoluble in alcohol-ether, but Abel showed that there are nitrocelluloses with 
13-2 per cent, of nitrogen and still soluble in this mixture, whilst others with only 12-8 per 
cent, are insoluble ; and that this depends on the method of preparation the duration of 
action of the mixed acids, the ratios and concentrations of the latter, and the temperature 
at which they act and on the nature, purity, and dryness of the cotton. Only by following 
exactly the directions is it possible to obtain a constant percentage of nitrogen and complete 
solubility or insolubility in the mixture of alcohol and ether. 

It was also once thought that guncotton was a nitro-compound in the true sense of 
the word, i.e. that the N0 2 groups were united directly to carbon. But first Bechamp and 
then others showed that it is a true nitric ester which can be saponified, with regenera- 
tion of . the cellulose, by alkalis, alkaline salts, ammonium sulphide, or ferrous chloride. 
It has been further shown that with the maximum of nitrogen an oxynitrocellulose 
is obtained [oxycellulose is (C 6 H 10 5 ) 3 + (C 6 H 10 6 ) n , so that the nitrocellulose will be 
C 6 H 7 (N0 2 ) 3 O 5 + C 6 H 7 (NO 2 ) 3 O 6 , and this with ferrous chloride gives oxycellulose ; nitro- 
mannitol, treated similarly, gives mannitol and not oxymannitol]. 

PROPERTIES OF GUNCOTTON. Under the microscope nitrocellulose 
has the same appearance as ordinary cotton, but in polarised light it appears 
iridescent. When moistened with a solution of iodine in potassium iodide 
and then with sulphuric acid, nitrocellulose becomes yellow and cellulose blue. 
It is somewhat less white than ordinary cotton, is rather rough to the touch and 
crackles when pressed with the fingers ; it becomes electrified when rubbed and 
then appears phosphorescent in the dark. It is soluble in ethyl acetate, nitro- 
benzene, benzene, acetone, &c., but insoluble in water, alcohol, ether, acetic 
acid or nitroglycerine, although a mixture of nitroglycerine and nitrocellulose 
is soluble in acetone, forming a jelly, cordite (see later). 

It resists the action of dilute acids, but is decomposed slowly by concen- 
trated sulphuric acid or hot alkali, and completely by hot sodium sulphide. 
Decomposition is also effected by iron and acetic acid or by ammonium sul- 
phide or ferrous chloride (Bechamp). 

Flocculent, loose guncotton has the sp. gr. 0-1, whilst the powder (pulp) 
has the sp. gr. 0-3 and is exploded by shock or percussion only at the point 
where it is struck, the explosion not being propagated to the whole mass. When 
ignited, it burns so rapidly that even when it is placed on black powder, the 
latter does not burn. 

In the form of cord, it burns more slowly and may be used as a rapid fuse. 
When wet or compressed it has a specific gravity varying from 1 to 1-3 (the abso- 
lute sp. gr. is 1-5) and it then burns slowly and cannot be exploded by percussion 
or by ordinary detonators ; explosion can, however, be induced by detonating 
a little dry guncotton with a fulminate of mercury cap. The decomposition 
proceeds according to the equation : 

2C 6 H 7 2 (ON0 2 ) 3 = 500 + 7C0 2 + 8H + 3H 2 + 6N. 

Less compressed guncotton gives more CO and H in comparison with the 
C0 2 and H 2 0, and hence has a less effect, the development of heat being smaller. 
No ash or smoke is formed, and 1 kilo of guncotton yields 741 litres of gas (the 
water being liquid, or 982 litres if the water is in the state of vapour), which is 
inflammable and, owing to the presence of carbon monoxide, poisonous. The 
temperature of combustion has been given as 6000 (i.e. 1071 Cals. are developed 
by 1 kilo). 

Unless guncotton is carefully prepared, it undergoes gradual change and 
may explode spontaneously, especially in the light, and to this are probably 



234 O R G A N I C C H E M I S T R Y 

due the great explosions which occurred formerly (1848-1862). Even dry, 
granulated guncotton becomes harmless and safe to handle if it is immersed 
for a moment in ethyl acetate, as it becomes coated with a gelatinous layer 
which dries it and preserves it, if moist, from further evaporation. 

Guncotton is transported in large quantities in the wet state in wooden 
boxes placed in others of zinc which are sealed hermetically to retain the 
moisture. It is stored in dry magazines which are situate at least 150 metres 
from any habitation and are not surrounded by earthworks so that the more 
serious effects due to projection of debris may not be added to those of an 
explosion. 

MANUFACTURE OF GUNCOTTON. Hanks of purified cotton, free from impurities, 
are employed. This cotton should fulfil certain requirements. 1 

The pure cotton is placed loose on trays which are arranged in a drying-stove heated 
by means of gilled pipes through which steam circulates ; the heating is continued until 
the proportion of moisture is less than 0-5 per cent., after which the cotton is allowed to cool 
for 12 to 15 hours in hermetically sealed boxes. If not pure the cotton is best defatted 
by boiling it for 2 to 3 minutes with 2 per ce'nt. sodium hydroxide solution ; it is then washed 
with water and subsequently treated with very dilute nitric acid in the hot. In some 
cases it is also bleached with a weak solution of hypochlorite, well rinsed with water and 
dried in a hot-air oven as above. When almost dry it is carded, dried completely, and, 

while still hot, placed in hermetically sealed boxes 
so that no more moisture may be absorbed. 

Nitration is then effected with a mixture of con- 
centrated nitric and sulphuric acid, as follows : 3 parts 
of pure sulphuric acid of sp. gr. 1-841 (96 per cent.) a ic 
poured into 1 part of pure nitric acid of sp. gr. 1-516, 
mixing taking place immediately and completely 
without the aid of stirrers. The mixture is then 
delivered with the help of an acid elevator (Monte/jus) 
into the nitration apparatus, consisting of a cast-iron 

FIG. 188. vessel, A (dipping pot) (Fig. 188), standing in a larger 

vessel, G, through which cold water circulates from 

H to J. The cotton is immersed in small portions (300 to 800 grms.) in the acid-bath and 
is stirred with an iron fork. In England 1 kilo of cotton is used per 160 kilos of the acid 
mixture, while in Germany 1 kilo of cotton is taken for every 40 kilos of acid ; after a 
short time (15 to 30 minutes) the nitrated cotton is removed with iron forks and is placed 
to drain on a cast-iron grid (grate), B and C, arranged on one side above the vessel ; before 
it is taken away, it is pressed with a cast-iron plate, F, connected with a lever, D E. 

The acid mixture is renewed when it has treated 30 to 50 per cent, of its weight of cotton ; 
also after each portion of cotton is removed from the bath, fresh acid mixture, equal to 
ten times the weight of the cotton taken out, is added in order to make up for what has been 
absorbed and combined. On the German system (where less acid is used) renewal takes 
place more frequently. Above each of the nitrating vessels is a hood with a strong draught 
to carry off the nitrous vapours which are always evolved. Excessive rise of temperature 
gives a guncotton which contains less nitrogen and shows less complete insolubility in 
alcohol-ether than are required in practice. 

In some factories the nitration is carried out in a number of small, deep and narrow, 
hemispherical vessels of cast-iron mounted on trolleys. These are charged in order with 
certain weights of acid mixture (30 to 50 kilos) and dry cotton (2 to 4 kilos), and, after 
thorough mixing, the trolleys are pushed into an oblong lead-lined chamber provided with 

1 Cotton for nitrocellulose should be pure white and should not contain dust or fibres of jute, hemp, or flax, 
or woody matter or pods ; these impurities, when separated by hand from 200 grms. of the cotton, should not 
exceed 0-5 grm. The filaments should not be too short, otherwise they form a paste during nitration. A small 
piece thrown into water should sink in two minutes. It should not contain more than 6-9 per cent, of substances 
soluble in ether (fats, &c.) ; in many factories 0-5 per cent, is not allowed. In England the amount of fat allowed 
is 1-1 per cent, extracted with ether in 4 hours in a Soxhlct apparatus (sea Analysis of Fats). The moisture, 
determined by heating the cotton in an oven at 100 until its weight remains constant, should not exceed 6 per rent, 
and the cotton merchant is debited with any excess and also with the cost of drying. 

When moistened with a few drops of water, the cotton should maintain a neutral reaction. 

The ash, estimated by heating a few grammes of the cotton to redness in a platinum capsule until it becomes 
quite white and of constant weight, should not amount to more than 0-3 per cent. 




MANUFACTURE OF GUNCOTTON 



235 



as many doors as there arc trolleys. A powerful aspirator draws the nitrous vapours 
into a wooden flue. A battery of soaking-pots is used in such a way that w.hen the last 
is introduced into the chamber the first has already finished reacting (30 to 40 minutes), 
and as the pots are of metal and relatively small and are in a strong draught, the heat 
developed is readily dispersed. The pets are removed from the chamber and taken to the 
neighbouring centrifugal machines, into which the contents of the pots, which are mounted 
on pivots, are tipped. The centrifuges are similar to those employed in sugar factories (see 
Sugar) and have a steel or leaded steel rotating basket ; aluminium ones have also been tried 
but not with great success. A few minutes' centrifugation at 1000 revolutions per minute 
removes the greater part of the acid from the guncotton ; the latter is immediately taken 
to the washing machines, while the acid recovered is revivified in the manner described 
on p. 227. If drops of water or lubricating oil fall on to the cotton during centrifugation, 
the mass sometimes undergoes sudden decomposition with formation of a dense cloud of 
brown vapour ; this does not constitute a serious danger, since usually it is not accompanied 
by explosion. 

In some factories the nitration is nowadays carried out directly in the centrifuges, 
which may be of naked or leaded steel or even of earthenware, although these are heavier 





FIG. 189. 



FIG. 190. 



and more fragile (see Figs. 189, 190). The latter consist of a double-walled earthenware 
basket, the inner wall, d and a, but not the outer one, being perforated ; the two walls being 
a slight distance apart, an annular space, c, is left, which has an outlet above in a number 
of holes, s, in the edge of the bush. The whole is bound with steel hoops, t, to prevent 
danger from projection in case of fracture. The dry cotton (7 to 8 kilos or more) is arranged 
peripherally inside the perforated basket, the acid being supplied by the tube, m ; the basket, 
surrounded by the jacket, 6, and the cover, z, both of earthenware, is set in motion by the 
shaft, p, driven by the belt, r. The acid is driven uniformly through the cotton by centri- 
fugal force, rises through the ring space, c, and issues from the holes, s, into the channel, e, 
whence a pipe, /, carries it to an elevator to be again circulated. The operation is of 
short duration, and the red vapours are emitted from the tube, g. During nitration, the 
velocity of the drum is relatively low, but at the end the velocity is increased ; the nitrated 
cotton can then be taken away at once to be washed. 

Use is, however, preferably made of steel centrifuges with circulation of the acid, as 
proposed by Selwig and Lange ; the basket, d, is perforated (Fig. 191) and the cover is of 
aluminium and hinged and is furnished with a large tube, o, communicating with the pipe 
of an aspirator, n. The basket is moved slowly and filled with the nitric-sulphuric mixture 
(e.g. 70 per cent. H 2 S0 4 , 23 per cent. HN0 3 and 7 per cent, water) up to the top edge ; 
the cotton is then introduced in packets (1 kilo per 50 kilos of acid) and the basket given 
a velocity of 20 to 30 turns per minute. This movement causes the acid to circulate 
continuously through the cotton, and in half an hour, the nitration of 6 to 8 kilos of cotton 
is complete ; the acid is then discharged and the velocity increased to remove as much 
acid as possible from the cotton, which is taken out and washed in the ordinary way. 



236 



ORGANIC CHEMISTRY 



Excessive prolongation of the centrifugal ion and excessive velocity are not only without 
advantage but involve increased danger of explosion. 

From August 1905 in the Royal Gunpowder Factory at Waltham Abbey (where 2000 
tons are produced per annum), guncotton has been made by the displacement process of 
J. M. and W. Thomson and Nathan, which is briefly as follows. 




FIG. 191. 

Into the earthenware basins, which are furnished with aluminium covers (Fig. 1 92) and are 
connected in groups of four by means of leaden pipes and also communicate with exhausters, 
600 litres of the nitric -sulphuric mixture are placed ; about 10 kilos of cotton are then 
introduced in small portions into each vessel and are pressed with perforated wrought -iron 
plates. The nitration lasts two and a half hours, and at the end water is introduced 
above the perforated plate, this displacing at the bottom a corresponding quantity of the 
acid ; the acid thus recovered is reinforced with oleum and strong nitric acid. The 
displacement lasts 3 hours, after which the mass is centrifuged and the cotton washed, 
rendered stable, pulped, &c. 




FIG. 192. 

Since guncotton should have a very definite nitrogen content, different from that of 
collodion-cotton used to gelatinise nitroglycerine (see later), the process of nitration is care- 
fully followed by numerous rapid analyses until suitable conditions are found for obtaining 
a constant product ; after this has been done, the final control is sufficient. It has been 
proposed to follow the extent of nitration of cellulose by observing its behaviour towards 
polarised light. In recent years it has been shown that guncotton of more constant type 
and more readily rendered stable is obtained if the acid mixture is renewed for each nitration ; 
the last processes described are hence to be preferred. 

WASHING. The nitrocellulose from the centrifuge is passed directly into the oval 
washing vessel (see. Fig. 193), which has a longitudinal partition down the middle (like 
the hollander machines us-ed in paper-making), and in which a shaft furnished with beaters 



PULPING 



237 



mixes the whole mass with water ; the latter is constantly renewed and the washing 
continued until the acid reaction towards litmus paper disappears (2 to 3 hours). The washed 
guncotton is either centrifuged again or put to drain in wooden baskets. Although it no 
longer exhibits an acid reaction, yet, as was shown by J. Tonkin in 1862 and by Abel in 
1865 (in England), it still contains acid or rather unstable sulphuric esters in the small 
channels of the fibres. 

To separate these remaining traces of acid, the nitrocellulose is rendered stable by 
boiling it for two consecutive periods of 12 hours each with water in wooden vats fitted with 
perforated false bottoms (one vat holds even more than 1000 kilos of the cotton), beneath 
which steam is passed. Then follow four more boilings of 4 hours each with water (formerly 
one or two boilings with calcium carbonate were also carried out), and finally two or three 
boilings each of 2 hours with fresh water. This system of washing was proposed by 
Dr. Robertson and employed with advantage in the Government Factory at Waltham Abbey ; 
it lasts altogether 48 hours, is preferable to that in which the boilings are short at the 
beginning and long at the end, and especially to that where boiling with, soda is interposed, 
as the soda hydrolyses the nitrocellulose and transforms it partially into collodion -cotton 
poor in nitrogen and soluble in alcohol-ether. 

Some of the boiling may be dispensed with if the nitrocellulose is steamed in closed vats. 




FIG. 193. 

PULPING. In spite of all the washing and boiling to which it is subjected, the guncotton 
persistently retains a trace of acid, and to remove this, the cotton is thoroughly defibred 
(pulped) as was proposed by Tonkin and by Abel in 1865. This operation is carried out in hoi- 
landers similar to those used for the preceding washing and identical with those used in the 
manufacture of cellulose for paper (see later, section on Paper, for figures and cross -sections). 

Pulping lasts from 5 to 8 hours, according to the fineness required, but if it is incomplete, 
inconveniences are met with in the subsequent compression, the desired density not being 
attainable ; also if pulping is carried too far, the compression is disturbed in another 
way. Guttmann proposed the use of hot water in pulping, and this possesses several 
advantages in addition to saving time. In the large wooden vats, 'as much as 200 kilos 
of guncotton can be treated at one time. In some cases a little calcium carbonate is 
added to guncotton to preserve it and to neutralise any residual acid ; it is added in powder 
just before the completion of pulping. 

If the guncotton thus prepared does not answer the rigorous tests to which it is sub- 
jected (see later, Tests of Stability), it is rendered stable by again boiling it for some hours 
with water in large wooden tanks (sometimes lined with lead), jets of steam, and also of air to 
keep the mass moving, being passed in. In order to separate the water, the mass is placed 
in suitable centrifuges fitted with drums of fine metal gauze entirely surrounded by linen ; 
in other cases, the water is separated as in paper-mills by placing the mass in chambers 
having perforated brass floors covered with cloth, the pulp drained in this way being finally 
centrifuged. The water separated from the pulp is allowed to stand in suitable vessels 
to deposit the finer fibres it has carried away. After centrifugation, the pulp contains 
about 25 to 30 per cent, of water and in this state it can be kept safely in zinc boxes, in 



238 



ORGANIC CHEMISTRY 



which it can be transported if it is slightly compressed and the cover of the box soldered. 
If properly prepared, guncotton should not contain more than 3-5 to 4 per cent, of collodion- 
cotton (soluble in alcohol-ether), but in England 7 to 8 per cent, is allowed. 

COMPRESSION OF GUNCOTTON. For military purposes, that is, for cartridges 
and for the blocks used for charging torpedoes, the still moist guncotton is strongly com- 
pressed to render it safer and more powerful owing to the increased charging density 
(see above), which reaches the value 1-2 with pressures of 500 to 1000 atmos. Fig. 194 
shows in section a Taylor and Challen hydraulic press used for this purpose ; this is set 
up in an isolated room and can be controlled from a distance so as to avoid any great amount 
of damage in case of explosion during the compression, this mostly happening if any hard 
foreign body chances to be present in the guncotton. 

To obtain the greatest density, the pulp is first washed with hot water and slightly 
compressed in the mould, d, by means of the lever, h, the water being drawn away under 
the perforated base, c (covered with steel gauze), by a pump connected with the tube, I. 




FIG. 194. 



The partitions, I, are raised and the mould passed through an aperture in the wall, M 
(which serves as a protection for the workmen), and thus above the plate, n, of the hydraulic 
press ; this plate is kept horizontal by four columns, S'. The mould is raised by the piston, 
t , of the press so that it is pressed against a die, r, fixed to the cover, q. This cover is held 
fast by the four columns so that the die penetrates the mould and compresses the cotton 
under a pressure of 800 to 1000 atmos. The degree of humidity after the compression is 
about 10 per cent., and at each operation a block of 1 kilo is made, the shape being adapted 
to that of the projectile. Thus compressed, guncotton is so hard and compact that it can 
be worked quite safely with the plane, saw, or boring tool, a fine jet of water being directed 
at the point where the cutting is taking place. To prevent compressed guncotton from 
losing moisture and from becoming mouldy, it is dipped in molten paraffin wax ; or, better, 
it is immersed for a moment in ethyl acetate (or acetone), which dissolves a little nitro- 
cellulose at the surface and forms a kind of impermeable varnish. 

The theoretical yield of dry guncotton is 185 kilos per 100 kilos of dry 
cotton ; practically 171 to 176 kilos are obtained. 

USES OF GUNCOTTON. For the charging 'of torpedoes, moist com- 
pressed guncotton has replaced all other explosives. It is used also for rilling 
grenades, which are then covered with molten paraffin wax to unite the grenade 
and the explosive ; explosion is effected by a detonator of dry guncotton. It 
is made also into compressed cartridges for use in mines, a cavity being left for 
the detonating cap and the fuse. 



COLLODION-COTTON 289 

Mixtures of granulated guncotton and nitrates are placed on the market 
undsr the namss of tonite, potentite, &c. Abel obtained beautiful, pyrotechnic 
effects by saturating guncotton with solutions of various mineral salts capable 
of imparting different colours to the flame. It is sometimes used for filtering 
acids, alkalis, and solutions of permanganate, being resistant to these reagents 
in the cold. Also it is in some cases employed as an electric insulator and 
for bandaging purulent sores and wounds, being first saturated with 
potassium permanganate. 

COLLODION-COTTON FOR GELATINE DYNAMITE, DYNAMITE, AND 
SMOKELESS POWDERS. During recent years, a different, less nitrated nitrocellulose, 
collodion-cotton, has assumed very great importance in the manufacture of smokeless 
explosives. On the other hand, guncotton itself has, of late years, been largely replaced 
by compressed, crystalline, or fused trinitrotoluene (see Part III), especially for military 
and naval purposes. Collodion -cotton was at one time thought to be dinitrocellulose, 
soluble in a mixture of alcohol and ether, but it has now been shown to be a mixture of 
various soluble nitro -compounds, which are formed under different conditions from those 
yielding guncotton. Collodion -cotton should have a constant nitrogen -content, and it 
should be readily soluble in a mixture of alcohol (1 part) and ether (2 parts), giving a 
dense viscous solution. If it answers these requirements, it gelatinises nitroglycerine well 
and dissolves completely in it ; attention is, however, also paid to the time necessary 
for gelatinisation. 

For photographic plates, extensive use was formerly made of ethereal -alcoholic solutions 
of soluble nitrocellulose (collodion), and in this case importance was attached not so much 
to the viscosity as to the proportion of nitrocellulose which would yield an elastic film 
of marked resistant properties. For this purpose, the nitration is carried out at a 
temperature of at least 40 to 50, so that the resulting collodion is less viscous ; also 
the nitrocellulose is not pulped. 

The cotton is immersed for 60 to 90 minutes in a mixture of 1 part of 96 per cent, 
sulphuric acid (sp. gr. 1-840) and 1 part of 75 per cent, nitric acid (sp. gr. 1-442) at a 
temperature of about 40. 

The more concentrated the acid and the more prolonged its action, the higher will be 
the nitrogen -content, but the viscosity will not be decreased ; a high temperature, however, 
results in diminution of the proportion of nitrogen and also of the viscosity. 

The nitration can be effected in the cold, but more concentrated acids and more pro- 
longed action are then required. After nitration collodion -cotton intended for the 
manufacture of gelatine dynamite goes through all the operations of washing, pulping, 
and boiling employed with guncotton. 

Collodion cotton for gelatine dynamite or smokeless powder must be subjected to a 
drying process. Since the centrifuged pulp still contains 30 per cent, of water, whilst 
nitrocellulose begins to decompose at 70 (or even at 50 if badly prepared) and in 
the dry state is very sensitive to shock or percussion, the drying of collodion-cotton con- 
stitutes a very dangerous operation. At one time it was dried by means of indirect steam, 
but nowadays it is placed on iron plates heated to 40 to 50. When dry, it sometimes 
becomes electrified on rubbing, and this phenomenon explains the frequent spontaneous 
fires formerly occurring in the drying ovens. Guttmann prefers to dry the collodion-cotton 
on copper plates connected with the earth by wires (to discharge the electricity). These 
plates are perforated with conical holes 0-25 mm. wide at the top and 1 mm. at the bottom ; 
strips of leather are used to prevent rubbing of the metal parts. In these ovens, the pulp 
is spread out and is subjected to the action of a current of air heated to 40 (in some case," 
also dried) and in two days the mass is dry, not more than 0-1 per cent, of moisture being 
then present. The dried material is then carefully placed in rubber bags and stored in 
air-tight boxes. 

The drying ovens are provided with alarm-thermometers, which also regulate the 
temperature automatically. 

Drying in a vacuum is also employed (especially with fulminate of mercury) and is then 
more rapid and takes place at a lower temperature, while the danger of an explosion 
is diminished owing to the absence of the tamping effect of the atmospheric pressure (see 
p. 221). 



240 ORGANIC CHEMISTRY 

Collodion -cotton for making ballistite (see later) should contain 11-75 to 11-95 per cent, 
of nitrogen, whilst that for ordinary gelatine dynamites contains as much as 12 per cent. 

SMOKELESS POWDERS. Even 50 years ago attempts were made to diminish the 
smoke produced by ordinary gunpowder by diminishing the amount of sulphur present, 
but its relations to the nitre and carbon cannot be greatly altered. Potassium nitrate was 
then replaced by ammonium nitrate, but this was found to be too hygroscopic ; yet later, 
ammonium picrate was employed with better, but still not satisfactory, results. In 1864 
Schulze prepared a smokeless powder from nitrocellulose obtained from pure wood-cellulose. 
It gave good results with sporting guns, but was too shattering for use in warfare, and the 
same was the case with a smokeless powder prepared in 1882 by Walter Reid by granulating 
nitrocellulose and gelatinising it superficially with alcohol and ether. 

The true solution of this important problem is due to Vieille, who in 1884 found that the 
shattering action of guncotton could be transformed into a progressive (or propellant) action 
by destroying the fibrous structure with suitable solutions. To attenuate the rapidity of 
explosion of guncotton it must be made as dense as possible (theoretically the fibre free 
from interstices has the density 1-5) and this cannot be done practically with fibrous 
cotton (even when pulped) as a pressure of 4000 atmospheres would be necessary. Vieille, 
however, dissolved or gelatinised the nitrocellulose and then recovered it by evaporating 
the solvent. 

With the smokeless powder prepared by Vieille in 1885 the velocity of projectiles from 
cannon was increased by 100 metres per second over that obtained with ordinary powder, the 
pressure in the cannon being the same in the two cases ; hence guns of smaller calibre 
could advantageously be employed. 

This amounted to a revolution in the region of ballistics, since, in addition to the advan- 
tages of no smoke or ash, and of the use of lower calibres, there was also the possibility of 
charging empty projectiles with these explosives, which are made and kept so safely. 
Gelatinisation is effected by solvents of nitrocellulose, i.e. by ether, acetone, ethyl acetate, 
nitroacetylglycerine, &c. (see p. 223). 

I. SMOKELESS POWDERS OF PURE NITROCELLULOSE. The quantity of 
dry nitrocellulose (6 to 10 per cent, of the weight of solvent) decided on is introduced into 
the kneading machine (see p. 243), whi