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Full text of "Technical methods of chemical analysis. Edited by George Lunge in collaboration with E. Adam, [and others] English translation from the latest German ed., adapted to English conditions of manufacture"

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L 



TECHNICAL METHODS OF 
CHEMICAL ANALYSIS 



U'^xi 



TECHNICAL METHODS 

OF 

Chemical Analysis 



Edited by GEORGE LUNGE, Ph.D., Dr.Ing. 

EMERITUS PROFESSOR OF TECHNICAL CHEMISTRY, FEDERAL POLYTECHNIC SCHOOL, ZURICH 



IN COLLABORATION WITH 



E. ADAM. 
P. AULICH. 

F. BARXSTEIN. 
E. BERL. 

O. BOTTCHER. 
A. BUJARD. 
C. COUN'CLER. 
K. DIETERICH. 
K. DCMMLER. 
A. EBERTZ. 



A. EIBXER. 

C. V. ECKEXBRECHER. 

F. FISCHER. 

P. FRANK. 

H. FREUDENBBKQ. 

E. GILDEMEISTER. 

R. GXEHM. 

O. GUTTMANN. 

E. HASELHOFF. 

W. HERZBERG. 



D. HOLDE. 
H. KOHLER. 

W. KLAPPROTH. 
P. KREILIXG. 
K. B. LEHMAXN, 
J. LEWKOWITSCH. 
C. J. LIXTXER. 

E. O. V. LIPPMAXX. 
E. MARCKWALD. 

J. MESSXER. 



J. PASSLER. 
O. PFEIFFER. 
O. PUFAHL. 
O. SCHLUTTIG. 
C. SCHOGH. 
G. SCHULE. 
L. TIETJEX3. 
K. WINDISCH. 
L. W. WIXKLER. 



ENGLISH TRANSLATION 

FROM THE LATEST GERMAN EDITION, ADAPTED TO ENGLISH 
CONDITIONS OF MANUFACTURE 

EDITED BY 

CHARLES ALEXANDER KEANE, D.Sc, Ph.D. 

PRINCIPAL AND HEAD OF THE CHEMISTRY DEPARTMENT 
THE SIR JOHN CASS TECHNICAL INSTITUTE, LONDON 



IX COLLABORATION WITH 



W. BACOX. 

T. L. BAILEY. 

C. O. BAXXISTER. 

E. J. BEVAX. 

W. BURTOX. 

J. C. CAIX. 

W. A. GASPARI. 

E. G. CLAYTON. 



H. G. COLMAX. 
J. T. COXROY. 
C. F. CROSS. 
W. A. DAVIS. 
L. EYXOX. 
G. J. FOWLER. 
A. G. GREEX. 
O. GUTTMAXX. 



A. D. HALL. 

J. HUBXER. 

G. CECIL JOXES. 

W. J. LAMBERT. 

J. LEWKOWITSCH. 

A. R. LIXG. 

C. A. MITCHELL. 

G. W. MOXIER-WILLIAMS. 



F. B. POWER. 
H. R. PROCTER. 
H. J. L. RAWLINS. 
A. RULE. 
W. F. REID. 
P. SCHIDROWITZ. 
A. SMETHAM. 
W. THOMASOX. 



VOLUME lll.-PART I. 



3 ^J^ b 






GURNEY AND JACKSON ^ 
33 PATERNOSTER ROW, LONDON 

1914 



I 



TP 

6/ 

■ 

r 



PREFACE 

The sections comprised in this third and concluding volume of the 
English edition are included in the third and fourth volumes of 
the last German edition, published in 1910-11. 

The sections on "Brewing Materials and Beer" and on " Vinegar" 
have been entirely re-written for the English edition, as the processes 
of manufacture and associated methods of analysis that obtain in 
this country are so entirely different from those of Germany ; and the 
sections on " Spirits " and on " Brandy and Liqueurs " of the German 
edition have been combined into one section under the title of 
"Alcohol, Potable Spirits, and Liqueurs," and have been fully revised, 
so as to provide a connected account of the analytical methods required 
by the English conditions of manufacture and of legislative control. 

All the remaining sections have been submitted to English experts 
for revision. The contents of the volume have thus been brought 
thoroughly up to date by the addition of all relevant matter of 
importance since the issue of the last German edition. 

Also, the order of the sections in the German edition has been 
altered, with the object of securing a somewhat better sequence of the 
subject matter. 

With the exception of those cases in which empirical factors are 
employed in technical work, all the numerical data are calculated from 
the table of atomic weights for 1914, issued b}' the International Com- 
mittee, with 0=16 as the basis. As in Volumes I. and II., the 
numerical data for gases, and for the weights of substances to be 
taken for analysis so as to correspond to definite volumes of gases, 



viii PREFACE 

are calculated from the real litre weights according to the most reliable 
determinations, not from the calculated values. Also, all temperatures 
arc given in Centigrade degrees, except where otherwise stated. 

The Editor desires to record his thanks to Mr J. S. S. Brame, 
Lecturer on Fuel, The Sir John Cass Technical Institute, for very 
kindly reading the proofs of the sections on "Mineral Oils" and 
" Lubricating Oils," the MSS. of which had been revised by the late 
Dr Lewkowitsch ; to the Director of Navy Contracts, for a copy of the 
Admiralty specification governing the supplies of manufactured rubber; 
and to Mr L. Archbutt, for permission to reproduce the illustration of his 
vaporimeter. Also to Messrs Baird & Tatlock, Messrs A. D. Cillard 
(Paris), Messrs Constable & Co., and Messrs C. Griffin & Co., for the 
loan of and permission to reproduce blocks ; and to Messrs Macmillan 
& Co., for permission to reproduce a block from their publication, 
India-rubber Laboratory Practice^ by W. A. Caspari. 

CHARLES A. KEANE. 
London,////;/ 1914. 



LIST OF CONTRIBUTORS TO THE GERMAN 
EDITION, AND OF REVISERS AND 
AUTHORS OF THE ENGLISH TRANS- 
LATION IN VOL. III. 

Mineral Oils. 

By Prof. D. Holde, Lichterfelde. 

Revised by the late J. Lewkowitsch, Ph.D., M.A. 

Lubricants. 

By Prof. D, HOLDE, Lichterfelde. 

Revised by the late J. Lewkowitsch, Ph.D., M.A. 

Oils, Pats, and "Waxes. 

By the late J. Lewkowitsch, Ph.D., M.A. 
Revised by The Author. 

Special Methods of Analysis Employed in the Oil and Pat Industries. 
By the late J. Lewkowitsch, Ph.D., M.A. 
Revised by The Author. 

Resins, Balsams, and Qum-Resins. 

By K. Dieterich, Ph.D., Dresden. 

Revised by the late J. Lewkowitsch, Ph.D., M.A. 

Drugs and Galenical Preparations. 

By K. Dieterich, Ph.D., Dresden. 
i?tfz//V<f^^/ F. B. Power., Ph.D., LL.D. 

Essential Oils. 

By E. Gildemeister, Ph.D., Leipzig. 
Revised by F. B. POWER, Ph.D., LL.D. 

Tartaric Acid. 

By W. Klapproth, Dr.Ing., Nieder-Ingelheim. 
Revised by W. A. Davis, B.Sc. 

Citric Acid. 

By W. Klapproth, Dr.Ing., Nieder-Ingelheim. 
Revised by W. A. Davis, B.Sc. 

Organic Preparations. 

By J. Messner, Ph.D., Darmstadt. 

Revised by Charles A. Keane, D.Sc, Ph.D. 



X LIST OF CONTRIBUTORS 

India-rubber and Rubber Goods. 

By F. Frank, Ph.D., and E. Marckwald, Ph.D., Berlin. 
Revised by W. .X. Caspari, Ph.D., H.Sc. 

Vegetable Tanning Materials. 

By the late Prof. C. Councler, Munden. 
Revised by Prof. H. R. Procter, M.Sc. 

Leather. 

By J. Paessler, Ph.D., Freiberg. 
Revised by Prof. H. R. PROCTER, M.Sc. 

Ink. 

By O. SCHLUTTIG, Dresden. 
Revised by C. \. Mitchell, B.A. 

Sugar. 

By Prof. E. O. VON Lippmann, Halle. 

Revised by P^KT'AXi-R. R. Ling and Lewis Eynon. 

Starch and Dextrin. 

By Prof. C. voN ECKENBRECHER, Berlin. 
Revised by hKlWMK R. LiNG. 

Alcohol, Potable Spirits, and Liqueurs. 

By A. EiiERTZ, Ph.D., Hohenheim, and G. SCHULE, Ph.D., Strassburg. 
Revised by G. W. Monier-Williams, M.A., Ph.D. 

Vinegar. 

Re-written by G. Cecil Jones, A.C.G.I. 

Corresponding section in German Edition by G. Schule, Ph.D., Strassburg. 

Wine. 

By Prof. K. WiNDISCH, Hohenheim. 
Revised by P. SCHIDROWITZ, Ph.D. 

Brew^ing Materials and Beer. 

Re-writttn by ARTHUR R. LiNG and G. CECIL JONES, A.C.G.L 
Corresponding section in German Edition by Prof. C. J. LiNTNER, Munich. 

Pai>er. 

By Prof. W. Herzberg, Lichterfelde. 

Revised by C. F. CROSS, B.Sc, E. J. Bevan, and W. Bacon, B.Sc 

Textile Fibres. 

By Prof. R. Gnehm, Zurich. 
Revised by J. HiJBNER, M.Sc. (Tech.) 

Inorganic Colours. 

By Prof. A. ElBNER, Munich. 

Revised by H. J. L. Rawlins and A. Rule, D.Sc, Ph.D. 



LIST OF ABBREVIATED TITLES OF JOURNALS 



Journals. 



quee a I'lndustrie, k 
a la Biologie 



Acetylene 

American Chemical Journal 

American Journal of Science 

Analyst ..... 

Annalen der Chemie . 

Annalen der Physik . 

Annales de Chimie analytique appl 

TAgriculture, k la Pharmacie et 
Annales de Chimie et de Physik 
Annales des Falsifications . 
Archiv der Pharmacie 
Atti della Reale Accademia dei Lincei 
Berg und Huttenmannische Zeitung . 
Berichte der deutschen chemischen Gesellschaft 
Biedermann's Zentralblatt fiir Agricultur Chemie 
Bollettino chimico farmaceutico . 
Brewer's Journal 
British and Colonial Druggist . 
Bulletin de rAssociation Belgique des Chimistes 
Bulletin de I'Association chiraique de Sucre et de Distillerie 
Bulletin de la Societe chimique de Belgique 
Bulletin de la Societe chimique de Paris . 
Bulletin de la Societe Industrielle du Nord de la France 
Bulletin de la Societe Industrielle de Mulhouse 

Chemical News 

Chemical Trade Journal 

Chemiker Zeitung 

Chemiker Zeitung Repertorium . . . , 

Chemische Industrie ...... 

Chemische Revue iiber die Fett- und Harz-Industrie 
Chemisches Zentralblatt ...... 

Chemist and Druggist ...... 

Comptes rendus hebdomadaires des seances de I'Academie 

des sciences ..... 

Der Gerber 

Deutsche Gerber Zeitung .... 

Die landwirthschaftlichen Versuchs-Stationen 
Dingler's polytechnisches Journal 
Electrician ...... 

Electrochemical and Metallurgical Industry 
Electrotechnische Zeitschrift 



Engineer 



Abbreviations. 

Acetylene 
Amer. Chem. J. 
Amer. J. Sci. 

Analyst 
Annalen 
Ann. Physik 

Ann. Chim. anal. 

Ann. Chim. Phys. 

Ann. Falsific. 

Arch. Pharra. 

Atti R. Accad. Lincei 

Berg u. Hiitten. Zeit. 

Ber. 

Biedermann's Zentr. 

Boll. chim. farm. 

Brewer's J. 

Brit, and Col. Drug. 

Bull. Assoc. Belg. des Chim. 

Bull. Assoc. Chim. Sucr. 

Bull. Soc. Chim. Belg. 

Bull. Soc. Chim. 

Bull. Soc. Ind. Nord 

Bull. Soc. Ind. Mulhouse 

Chem. News 

Chem. Trade J. 

Chem. Zeit. 

Chem. Zeit. Rep. 

Chem. Ind. 

Chem. Rev. Fett-Ind. 

Chem. Zentr. 

Chem. and Drug. 

Comptes rend. 

Gerber 

Gerber Zeit. 

Landw. Versuchs-Stat. 

Dingl. polyt. J. 

Electrician 

Electrochem. Ind. 

Electrotech. Zeitsch. 

Engineer 



Xll 



LIST OF ABBREVIATED TITLES OF JOURNALS 



Journals. 

1". I ■ £J . • • • • • • 

Ei: - and Mining Journal 

Farben-Zciiung 

Farber-Zeitung 

P"ischer's Jahresbericht 

Gazzetta Chimica Italiana 

Gummi-Zeiiung ...... 

I ndia-ruilicr Journal ..... 

Industrie Blatt 

Intern.iiional Sugar Journrd .... 
Jahresbericht der chemischen Technologic 
Jahresbericht der Pharmazie .... 

Jahresbericht fur Chemie 

Journal of Analytical and Applied Chemistry . 
Journal de Pharmacie et de Chimie . 
Journal fiir Gasbeleuchtung und Wasserversorgung 
Journal fiir praktische Chemie .... 
Journal of Agricultural Science .... 

Journal of Gas Lighting 

Journal of Industrial and Engineering Chemistry 

Journal of Physical Chemistry .... 

Journal of the American Chemical Society 

Journal of the Chemical Society 

Journal of the Chemical Society, Abstracts 

Journal of the Chemical, Metallurgical, and Mining 

Society of South Africa 

Journal of the Franklin Institute .... 
Journal of the Institute of Brewing .... 
Journal of the Institution of Mechanical Engineers . 
Journal of the Institute of Metals .... 
Journal of the Iron and Steel Institute 
Journal of the Physical and Chemical Society of Russia 
Journal of the Ro3'al Society of Arts .... 
Journal of the Society of Chemical Industry 
Journal of the Society of Dyers and Colourists . 
Koninklijke Akademie van Wetenschappen te Amsterdam 

Proceedings (English Edition) . 

Leather Trades Review 

Le Stazioni sperimentali agrarie Italiana 

Mittheilungen aus dem kiJniglichen Materialpriifungsamt 

zu Gross-Lichterfelde West 
.Mittheilungen aus der Zentralstelle fiir wissenschaftlich 

technische Untersuchungen .... 

Mittheilungen dcs lechnischen Gewerbemuseums in Wien 
Monatshefte fiir Chemie der kaiserlichen Akademie der 

Wisscnschaften, Wien 
Monatsschrift fiir Textil-Industrie 
Monitcur Scicniifique 
Oesterrcichische Chemiker Zeitung 
Oesterreichisch-Unpar Zeitschrift fiir 

Landwirthschaft . 
Paper and Pulp .... 
Papier-Zeitung .... 
Petroleum Review 



Zuckerindustrie und 



AnBREVIATIONS. 

Engineering 

Eng. and .Min. J. 

Farben-Zeit. 

Farber-Zeit. 

Fischer's Jahresber. 

Gazz, Chim. Ital. 

Gummi-Zeit. 

India-rubber J, 

Ind. Bl. 

Int. Sugar J. 

Jahresber, d. chem. Techn. 

Jahresber. d. Pharm. 

Jahresber. f. Chem. 

J. Anal, and Applied Chem. 

J. Pharm. Chim. 

J. Gasbeleucht. 

J. prakt. Chem. 

J. Agric. Sci. 

J. Gas Lighting 

J. Ind. Eng. Chem. 

J. Phys. Chem. 

J. Amer. Chem. Soc. 

J. Chem. Soc. 

J. Chem. Soc. Abstr. 

J. Chem. Met. Soc, S. .Africa 

J. Franklin Inst. 

J. Inst. Brewing 

J. Inst. Mech. Eng. 

J. Inst. Metals 

J. Iron and Steel Inst. 

J. Russ. Phys. Chem. Soc 

J. Soc. Arts 

J. Soc. Chem. Ind. 

j. Soc. Dyers and Col. 

Proc K. Akad. Wetensch. Am- 
sterdam 
Leather Tr. Rev. 
Staz. speriment. agr. Ital. 

Mitt. k. .Materialpriif. 

Mitt. Zentralst. Wiss.-tech. 

Unters. 
Mitt, techn. Gew. .Museums 

Monatsh. 

Monatsschrift f. Te.\t.-Ind. 
Monit. Scient, 
Oesterr. Chem. Zeiu 

Oesterr.-Ungar Zeitschr. 
Paper and Pulp 
Papier-Zeil. 
Petrol. Rev. 



LIST OF ABBREVIATED TITLES OF JOURNALS 



XII 1 



Journals. 

Pharmaceutical Journal 
Pharmaceutical Review 
Pharmazeutisch Weekblad 
Pharmazeutische Zeitung . 
Pharmazeutische Zentralhalle 
Pharmazeutisches Zentralblatt 
Philosophical Magazine and Journal of Science 
Philosophical Transactions of the Royal Society . 
Proceedings of the American Academy 
Proceedings of the American Electrochemical Society 
Proceedingsof the American Institute of Mining Engineers 
and also Bulletin 

Proceedings of the Faraday Society .... 

Proceedings of the Institution of Civil Engineers 

Proceedings of the Institution of Mining and Metallurgy 

Proceedings of the Royal Society 

Revue Generale des Matiferes Colorantes 

Revue internationale des Falsifications 

Receuil des travaux chlmiques des Pays-Bas at de 1 

Belgique . 
Scientific American . 
Stahl und Eisen 
Tonindustrie Zeitung 

Transactions of the Institute of Mining and Metallurgy 
United States Consular Reports 
West Indian Bulletin . . . 

Wochenschrift fiir Brauerei 
Zeitschrift der analytischen Chemie . 
Zeitschrift der anorganischen Chemie 
Zeitschrift des Vereins der deutschen Zucker-Industrie 
Zeitschrift des Vereins deutscher Ingenieure , , 
Zeitschrift fiir angewandte Chemie .... 
Zeitschrift fiir chemische Apparatenkunde 
Zeitschrift fiir das gesammte Brauwesen . 
Zeitschrift fiir das landwirtschaftliche Versuchswesen in 

Osterreich ...... 

Zeitschrift fiir Elektrochemie . 

Zeitschrift fiir Farben Industrie . 

Zeitschrift fiir Farben- und Textil-Chemie 

Zeitschrift fiir offentliche Chemie 

Zeitschrift fiir physikalische Chemie .... 

Zeitschrift fiir Spiritusindustrie ..... 

Zeitschrift fiir Untersuchung der Nahrungs- und Genuss 
mittel ........ 

Zeitschrift fiir Zuckerindustrie in Bohmen . . . 



Abbreviations. 

Pharm. J. 

Pharm. Rev. 

Pharm. Weekblad 

Pharm. Zeit. 

Pharm. Zentralh. 

Pharm. Zentr. 

Phil. Mag, 

Phil. Trans. 

Proc. Amer. Acad. 

Proc. Amer. Electrochem. Soc. 

Proc. Amer. Inst. Min. Eng. ; 

Bull. Amer. Inst. Min. Eng. 
Proc. Faraday Soc. 
Proc. Inst. Civ. Eng. 
Proc. Inst. Min. and Met. 
Roy. Soc. Proc 
Rev. Gen. Mat. Col. 
Rev. intern. Falsif. 

Rec. trav. chim. 

Scient. Amer. 

Stahl u. Eisen 

Tonindustrie Zeit. 

Trans. Inst. Min. and Met. 

U.S. Cons. Reps. 

West Ind. Bull. 

Woch. f. Brau. 

Z. anal. Chem. 

Z. anorg. Chem. 

Z. Ver. deut. Zuckerind. 

Z. Verein. deutsch. Ingen. 

Z. angew. Chem. 

Z. fiir chem. Apparatenkunde 

Z. ges. Brauw. 

Zeitschr. f. landw. Versuchswesen, 

Osterr. 
Z. Elektrochem. 
Z. Farb. Ind. 
Z. Farb.- u. Text.-Chem. 
Z. offentl. Chem. 
Z. physik. Chem. 
Z. Spiritusind. 

Z. Unters. Nahr. u. Genussm, 
Z. Zuckerind. Bohm. 



CONTENTS 



Preface ........... 

List of Contributors to the German Edition, and of Revisers and 
Authors of the English Translation ...... 

Abbreviated Titles of Journals ....... 



PAOE 

vii 



IX 

xi 



PART I 



Mineral Oils. 



A. Crude Petroleum . . . . . 

I. Chemical Composition . . ' . 

II. Specific Gravity and Coefficient of 

Expansion . . . . . 
in. Determination of Contained Water 

IV. Determination of Mechanical Im- 
purities 

V. Yield of Naphtha, Burning Oil, 

Lubricating Oil, etc. 

VI. Flashing Point 

VII. Determination of Asphalt . 

VIII. Paraffin Wax . 

IX. Specific Heat 

X. Latent Heat of Evaporation o 

Petroleum Fractions 

B. Naphtha 

I. Specific Gravity ... 

II. Evaporation Test ... 

III. Fractional Distillation . 

IV. Flashing Point 

V. Risk of Explosion . 

VI. Heat of Combustion of Naphth; 
(Petrol) .... 

VII. Aromatic Hydrocarbons 

VIII. Oil of Turpentine 

IX. Degree of Purification . 

X. Solubility in Absolute Alcohol 

XI. Petroleum Spirit (Naphtha or 
"Normal Benzine") . 

XII. Petroleum Spirit for Varnishes 
and Oil of Turpentine Substitutes 

XV 



PAGE 

I 
2 



6 
8 

9 
II 

13 
U 

i6 

17 
17 
17 
i8 

19 

20 
20 
21 
21 
21 

21 

22 



C. Burning Oil 

I. Colour — 

1. Wilson's colorimeter 

2. Stammer's colorimeter 

II. Specific Gravity 

III. Viscosity 

IV. Solidifying Point . 

V. Flashing Point 
The Abel petroleum test apparatus . 
The Abel-Pensky petroleum test 

apparatus . . . . . 
Other apparatus for testing the flash- 
ing point 

VI. Ignition or "Fire Test" 

VII. Fractional Distillation . 

VIII. Degree of Purification 

1. Sulphur conipounds 

2. The acid test . . . . 

3. Determination of acidity 

4. Salts of naphthenic and sulphonic 

acids . . . . . 

5. Inorganic residue (ash) 

6. The " breaking " of petroleum 

IX. Unsaturated Hydrocarbons . 

X. Burning Quality .... 

XI. Illuminating Power 

XII. Solubility in Absolute Alcohol 

XIII. Determination of the Origin of a 
Petroleum ..... 

D. Gas Oils from Crude Petroleum . 

E. Transformer Oils .... 

F. Liquid Fuel for Internal Combustion 

Engines 



PAOB 

23 

24 

25 

27 

28 
28 
28 
29 

33 

35 
36 
36 
36 
36 
39 
39 

39 
40 
40 
40 
40 

41 

42 

42 
43 
43 

44 



XVI 



CONTENTS 



PAOK 

G.fuilOih(^M^isut,Astatki'). -45 

H. Dust-Laying Oils . . ■ 46 

I. Paraffin Wax 46 

K . T:ir and Pitch Rfsuiues (Petroleum Tar, 

Asphalt, and Pitch) . . . -47 

L. By-products of the Petroleum Industry . 50 

By-products of the refining operations . 50 

1. AciJ tar 5° 

2. Pitch 50 

3. Waste acid 5° 

M. Products of the Shale and Lignite In- 
dustries . . ■ . . •5'' 
Experimental distillation test . • 5' 

I. Shale Oil 52 

II. Lignite or Brown Coal Tar . 53 

III. Montan Wax . . . .54 
N. Osokerite and Ceresin . . . -55 

O. Ichthyol 56 

P, Peat Tar 57 

Literature 57 

Lubricants. 
The Substances used as lubricants . 58 

A. Mineral Oils 60 

Physical Tests 60 

I. Appearance . . . . .60 

(rt) Colour 60 

{U) Consistency . . . .61 
(f) Mechanical impurities . . 61 

II. Specific Gravity . . . .61 
{a) Determination of the specific 

gravity by means of the hy- 
drometer . . . .61 
(/') Determination of the specific 

gravity by pyknometers . 62 

III. Expansibility . . . .63 

IV. Viscosity 65 

Redwood's viscometer . . .66 
Sayboll's viscometer . . .68 
Engler's viscometer . . .68 
Viscosity of mixtures of oils . . 69 
Absolute viscosity . . . .69 

V. Behaviour of Oils at Low 

Temperatures . . . .70 
Quantitative comparison of fluidi- 
ties. The freezing point or cold 
test 72 

VI. Volatility and Inflammability . 74 
(;) Evaporation or volatility test . 74 

1. .\rchbutt's vaporimeter . , 74 

2. Schreil)cr's apparatus . . 76 



PACK 

A. Mineral Oils. — Physical Tests — Contd. 

VI. Volatility and Inflammability — 

Continued. 

ij!) The flashing point 

The " open " test 

The Pensky-Martens apparatus 

Gray's apparatus 
(() The ignition point 

VII. Optical Tests . 
Optical activity 
Refractiviiy . 

Chemical Tests 

VIII. Acidity and Free Alkali . 

IX. Rosin in Lubricating Oils . 

X. Liability to " Gum " or " Resinifi 

cation " of Lubricants 

XI. Formolite Reaction (Xastjukoff' 
Ten) 

XII. Behaviour towards Metals 

XIII. Moisture 

XIV. Mineral Ash . 

XV. Presence of Soap 

XVI. Admixtures of Fatty Oils 

XVII. Rosin Oils and Tar Oils 
XVIH. India-rubber 

XIX. Deblooming Agents and Per 
fumes .... 

XX. Water-soluble Substances 

XXI. Suspended Matter . 

XXII. Asphalt and Paraffin in Solu 
tion ..... 

XXIII. Changes Lubricating Oils 
undergo in Use . . . .96 

Recovered oils . . . -96 
Condenser water . . . -97 

B. Fatty Oils 97 

C. Mixtures 0/ Mineral and Fatty Oils . 97 

D. Vaseline . . . . . -97 

E. Solid Lubricants 98 

I. Appearance, etc. . . . -99 

II. Liquefying and Dropping Points 99 

III. Qualitative Examination . . 100 

IV. Quantitative Determinations . 100 
('/) Free acid . . . . ico 

(_h) Soap 100 

(() Neutral fats (glycerides) and 

unsaponiliable matter . .101 

(</) Water 10 1 

(<■) Glycerol loi 

(^/') Nitronaphthalene and Nitro- 
benzene ..... lOI 
(jf) Free lime .... loi 
(//) Impurities and adulterants . loi 



CONTENTS 



xvii 



F". Water-soluble Lubricants 
The solidifying point 
The emulsif) ing properties or 
bility in water 
Analytical examination 
{a) Volatile matter 
(3) Free organic acid . 
(c) Neutral fatty matter 
(jf) Soap 

Literature .... 



solu 



PAGE 

102 
102 



102 
I02 
I02 
I03 

103 

103 
104 



Oils, Fats, and Waxes. 

Classification of oils, fats, and waxes . 105 

The examination of oils, fats, and waxes . 106 

A. Physical Methods .... 106 

I. Determination of the Specific 

Gravity ..... 107 

II. Determination of the Melting 

Point and the Solidifying Point. 108 

III. Determination of the Refractive 
Index ..... 107 

The butyro-refractometer . .110 

IV. Determination of the Viscosity . 113 

V. Determination of the Solubility . 113 

VI. Optical Rotation . . -US 

B. Chemical Methods . . . . 1 14 

I. Quantitative methods . . .114 
(a) Characteristics . . .114 

1. Determination of the saponi- 

fication value . . .114 

2. Determination of the iodine 

value . . . . .116 

3. Determination of the Reichert 

(Reichert-Meissl or Reich- 
ert-Wollny) value . .119 
Determination of the acetyl-value . 120 
(3) Variables . . . .122 

1. Determination of the acid 

value ..... 122 

2. Determination of the content 

of glycerol . . . .123 

3. Determination of the unsa- 

ponifiable matter . . 124 

II. Qualitative Methods . . .125 

1. Oxygen absorption . . . 126 

2. Bromide test .... 127 

3. Colour reactions . . . 129 

C. Examination of the Fatty Acids . 130 

1. Determination of the neutralisa- 

tion value and the mean 
molecular weight . . -131 

2. Determination of lactones (An- 

hydrides) .... 132 



The examination of oils, fats, and 
waxes — Continued. 

C. Examination of the Fatty Acids — 
Continued. 

3. Determination of insoluble fatty 

acids . . . . .132 

4. Determination of soluble fatty 

acids . . . . -133 

5. Separation of saturated from 

unsaturated fatty acids . .134 

6. Examination of the saturated 

fatty acids . . . .136 
Arachidic acid . . . .136 

Stearic acid . . . .136 

7. Determination of oleic, linolic, 

linolenic and clupanodonic 
acids 137 

8. Determination of oxidised fatty 

acids 139 

D. Examination of Unsaponifiable 

Matter I39 

1. The examination of unsaponifiable 

substances which are naturally 

present I39 

(a) In oils and fats . • .139 
((5) In waxes .... 141 

2. The detection and determination 

of admixed unsaponifiable sub- 
stances • . . . • 142 

Literature 145 

Data for the identification of vegetable 

oils 146 

Data for the identification of animal oils . 148 
Data for the identification of vegetable 

and animal fats . . . .150 

Data for the identification of waxes . .152 

Special Methods of Analysis employed 
in the Oil and Fat Industries. 

A. Oil Seed, Oil Cakes, Crude Fats, etc. .154 

B. Edible Oils and Fats . . . .155 

1. Butter 155 

2. Margarine 159 

3. Lard, artificial lard, lard substitutes . 159 

4. Chocolate fats, cocoa-butter sub- 

stitutes . . . . • 159 

C. Wool Oils 160 

D. Lithographic Varnishes, Polymerised 

Linseed Oils . . . . . 161 

E. ^'Boiled" Linseed Oil, Linseed Oil 

Varnish, Varnish Oils . . .162 

1. Linseed oil 162 

2. Siccatives 163 

b 



XVlll 



CONTENTS 



PAGE 

F. Ltnsud Oil Patnts and I'arntshfs . 1 66 

G. Oxuhsed Oils 169 

1. Oxidised oils obtained from semi- 

drying vegetable oils, marine animal 
oils, and liquid waxes . . . 169 

2. Oxidised oils obtained from drying 

oils 169 

H. Vulcanise J Oils, In Jia-rubber Substitutes 170 



J. Sulphonattd Oils, Turkey Red Oils . 1 70 
K. Tlie Candle Industry . . . .173 

1. Stearine candles . . '73 
(<j) Testing of the raw material . 174 
(/') Testing of intermediate and 

5nished products . . .176 

2. Paraffin candles . . . '179 

3. Spermaceti candles .... 1S3 

4. Wax candles, beeswax c;indles. . 183 

5. Ceresin 187 

L. Soap 188 

Soda soaps 18S 

Potash soaps (soft soap) . . .189 
Raw materials ..... 190 

{ii) Determination of the fatty 

matter and total alkali . . 191 

{b") Determination of combined alkali, 
free caustic alkali, and alkaline 
salts. Free fatty acids . .193 

(f) Determination of water . -194 

{d) Examination of fatty matter 

("soap stock ") . . . . 194 

1. Rosin acids .... 195 

2. Neutral fat . . . .196 

3. Unsaponifiable matter . . 196 
{e) Substances insoluble in alcohol . 197 

1. Water-soluble substances . .197 

2. Substances insoluble in water . 197 

3. Organic matter . . -197 
(/) Other substances which occur in 

soaps ..... 198 

1. Glycerol 198 

2. Sugar (saccharose) . . . 198 

3. Carbolic acid . . . -199 
Metallic soaps . . . . .199 

M. Glycerin ...... 200 

I. Crude glycerin .... 200 

(rt) Crude saponification glycerin . 2CO 

(/') Crude distillation glycerin . . 201 
(c) Crude soap-lye glycerin ; crude 

soap glycerin .... 202 

a. Distillation glycerin ; dynamite 

glycerin ..... 202 

3. Chemically pure glycerin . . 206 

Literature 209 



PAOB 

Resins, Balsams, and Gum Resins. 

A. Methods of .\n.ilysis . . . .211 
(a) The acid value . . . .212 

1. By direct titration . . .212 

2. By indirect titration . . .212 

3. By estimating the acid value of 

the volatile acids . . •213 
(/') The saponification value . .213 

1. Determination in the hot solution. 213 

2. Determination in the cold solution 214 
(<:) The ester value . . . .214 
(./) Lois at 100° (moisture). . .214 

(j) Ash 214 

(/) The proportion soluble in alcohol. 215 
Cc) The proportion insoluble in alcohol 215 
(/•) Specific gravity at 15° . . . 215 
(;) Determination of thecinnamein and 

resin esters in Peru balsam . -Sis 
{k") The acetyl, carbonyl, and methyl 

values 3i6 

(/) Examination of the resin acids . 216 
0") Qualitative reactions . . .216 

B. Characteristic Values and Standards 

of Quality 



I. Balsams 
Copaiba 

II. Resins 
Amber 
Benzoin 
Colophony 
Copal (Zanzibar) 
Dammar . 
Guaiacum 
Mastic (Levant) 
Pine resin 
Sandarac . 
Storax 
Turpentine 

in. Gum Resits 
Ammoniacum . 
^ Galbanum 
Myrrh 
Olibanum 
Literature 



217 

217 
217 

218 
?i8 
218 
218 
219 
219 
219 
220 
220 
220 
221 
221 
221 
221 
222 
222 
222 
222 



Drugs and Galenical Preparations. 
Drugs ...... 224 



Gambir 
Pegu catechu 
Ergot 
Isinglass . 
Opium 
Vegetable drugs 



224 

225 
225 
226 
230 

232 



CONTENTS 






xix 




PAGE 




PAOE 


A. Drugs. — Vegetable Drugs — Cojitd. 




B. Galenical Preparations 


. 252 


I. Barks 


232 


Papers 


• 253 


Cascara sagrada . 


232 


Test papers . 


. 253 


Cascaiilla .... 


232 


Mustard paper and mustard lint . 253 


Cinchona .... 


233 


Plasters . 


. 254 


Cinnamon and cassia 


235 


Liquid or fluid extracts 


• 255 


Condurango .... 


235 


Liquid extract of kola 


. 255 


Frangula .... 


235 


Thick extracts and dry extracts . 256 






Tinctures . 


• 257 


II. Bulbs 


236 


Ointments 


. 257 


Squill 


236 


Mercurial ointment 


. 257 


III. Flowers .... 


. 236 


Literature 


. 258 


Chamomile flowers 


236 






Red poppy petals .... 


237 


Essential Oils 


, 


Rose petals .... 


237 


Determination of the physical constants . 260 


IV. Fruits .... 


237 


Specific gravity . 


. 260 


Buckthorn berries . 


237 


Optical rotatory power 


. 260 


Capsicum, Spanish pepper, cayenne 




Solubility . 


. 260 


pepper .... 


237 


Congealing point 


. 260 


Elder berries 


238 


Fractional distillation . 


. 261 


Fennel 


238 


Chemical methods of examination . . 262 


Juniper berries 


238 


Determination of esters by sa 


ponification 262 


Parsley fruit . 


238 


Determination of free alcohols by acety- 


Poppy capsules 


239 


lation . 


. 263 


V. Herbs 


. 239 


Aldehyde determination by 


the bisul- 


Carduus benedictus 


239 


phite method 


. 264 


Linaria ..... 


239 


Determination of aldehydes and ketones 


Marjoram .... 


239 


with neutral sulphite 


. 265 


Milfoil or yarrow . 


239 


Determination of phenols 


. 266 


VI. Leaves .... 


239 


Detection of alcohol 


. 266 


Belladonna .... 


240 


Detection of fatty oil . 


. 267 


Coca 


241 


Detection of mineral oil 


. 267 


Digitalis .... 


242 


Detection of turpentine oil 


. 268 


Menyanthes .... 
Senna 


244 
244 


Constants and properties of some essential 


oils of commercial and industrial im- 


Strammonium 


244 


portance . 






. 208 


Uva ursi .... 


244 


Anise oil 
Bay oil 






. 268 
. 269 


VII. Rhizomes 


245 


Bergamot oil 






. 269 


Galangal .... 


245 


Bitter almond oil 






. 269 


Ginger ..... 


245 


Caraway oil 






. 270 


Hydrastis .... 


245 


Cassia oil 






. 271 


Male fern .... 


246 


Cinnamon oil 






. 271 


Rhubarb .... 


246 


Citronella oil 






. 271 


VIII. Roots .... 


247 


Clove oil 






. 271 


Belladonna .... 


247 


Eucalyptus oil 






. 273 


Gentian .... 


248 


Fennel oil . 






. 274 


Ipecacuanha .... 


248 


Geranium oil 






. 274 


Liquorice .... 


249 


Lavender oil 






. 274 


Rhatany .... 


249 


Lemon oil . 






• 274 


Senega 


250 


Lemon-grass oil 






• 274 


Valerian .... 


250 


Linaloe oil . 






• 275 


IX. Seeds .... 


250 


Mustard oil . 






. 275 


Kola seeds, kola nuts . 


250 


Nutmeg oil . 






. 276 


Black mustard seed 


252 


Orange oil . 






. 276 



XX 



CONTENTS 



Constants and properties 


of some essential 


oils of commercial and industrial im- 


po rtan ce — Continued. 




Orange flower oil 


. . 276 


Palmarosa oil 




. 276 


Patchouli oil 




. 276 


Peppermint oil 




. 276 


Rose oil 




• 277 


Rosemary oil 




• 277 


Sandalwood oil . 




• »77 


Sassafras oil 




• 277 


Spike oil 




. 278 


Star-anise oil 




. 278 


Thyme oil . 




. 278 


Turpentine oil 




. 278 


Literature 




. 280 


Tartaric Acid. 




I. Raw Materials . 


. 282 


I. Estimation of acid potassium ta 


rtrate 283 


2. Estimation of the total tartaric 


acid . 284 


The "Goldenberg Method, 189 


8" . 285 


The "Goldenberg Method, 190 


7" . 287 


3. Other estimations . 


. 289 


II. Control of Working Conditions 


. 290 


Calcium tartrate . 


. 291 


Tartaric acid liquors 


. 291 


Old liquors .... 


. 291 


Waste products. Lees residue 


and 


gypsum 


. 291 


Washings or "runnings " 


. 291 


Free sulphuric acid in liquors 


. 291 


Harmful impurities (" Impurity Rr 


itio") 292 


III. Finished Products . 


. 292 


Tartaric acid 


. 292 


Rocheile salt 


• 295 


Tartar emetic 


• 295 


Neutral potassium tartrate, borax t 


artar, 


iron tartrate . 


• 295 


Literature 


. 


• 295 



Citric Acid. 

I. Raw materials . . • . . 296 
Calcium citrate ..... 297 
Lime juice, lemon juice, and factory 

citric acid liquors .... 298 

II. Control of Working Conditions. . 299 

III. Final Products .... 300 
Literature ..... 



Organic Preparations. 

Acetaldehyde .... 
Aceianilide .... 
Acetic acid .... 



300 



301 
303 
304 





f AGK 


Acetone 


308 


Acetyl salicylic acid (aspirin) . 


310 


Amyl acetate 


311 


Amyl nitrite ..... 


312 


Apomorphine hydrochloride 


313 


-Atropine ...... 


315 


Atropine sulphate .... 


315 


Benzaldehyde ..... 


316 


Benzoic acid 


319 


Bromoform ..... 


• 321 


Caffeine 


322 


Caffeine-sodium salicylate 


322 


CafiFeine-sodium benzoate 


323 


Camphor 


323 


Carbon bisulphide .... 


325 


Carbon tetrachloride 


326 


Casein • 


327 


Catechol (pyrocatechin) . . . . 


329 


Chloral hydrate . . . . . 


330 


Chloroform ..... 


332 


Cinnamic acid 


336 


Citric acid 


337 


Cocaine hydrochloride 


338 


Coumarin ..... 


340 


Dextrose 


341 


Diethyl barbituric acid (veronal) 


• 343 


Veronal-sodium .... 


344 


Ethyl acetate 


344 


Ethyl alcohol 


345 


Ethyl bromide 


347 


Ethyl butyraie .... 


348 


Ethyl ether 


350 


Formaldehyde ..... 


351 


Formic acid 


352 


Gallic acid 


353 


Gelatin ...... 


355 


Guaiacol ...... 


356 


Guaiacol carbonate .... 


356 


Hexamethylenetetramine . 


357 


Hydroquinone (quinol) . 


358 


Iodoform 


359 


Lactic acid ..... 


360 


Methyl alcohol (wood spirit) . 


362 


Morphine 


365 


Morphine hydrochloride . 


365 


Codeine (methyl morphine) . 


367 


Dionine (ethyl morphine hydrochloride 


) 367 


a-Naphthol 


368 


/3-Naphthol 


369 


Oxalic acid 


370 


Paraldehyde 


371 


Phenacetine 


372 


Phenyidimethylpyrazolone (antipyrine) 


• 374 


Phenylhydrazine .... 


374 


Phthalic acid 


376 


Phthalic anhydride 


376 



CONTENTS 



XXI 



Pyrogallol 377 

Quinine ....... 378 

Quinine sulphate ..... 378 

Quinine hydrochloride .... 380 

Resorcinol ...... 382 

Saccharin ...... 383 

Salicylic acid ...... 385 

Salol 387 

Santonine ...... 388 

Strychnine 388 

Strychnine nitrate ..... 389 

Sulphanilic acid ..... 389 

Sulphonal ...... 390 

Tannin (tannic acid) .... 391 

Theobromine ...... 392 

Theobromine-sodium salicylate . . 393 

Thymol ....... 394 

Vanillin 395 

Literature ...... 397 

India-rubber and Rubber Goods. 

A. Crude and Vulcanised Rubber . . 398 
The examination of crude rubber . . 399 

I. Determination of Resin, Moisture, 

and Ash ..... 400 

II. The Direct Determination of 

Rubber 401 

(a) The Tetrabromide method . 402 
(<5) Nitrosite methods . . . 403 

I. Alexander's method . . 403 

II. Harries' method . . . 404 
(c) Schneider's method. . . 405 
{(T) Fendler's method . . . 406 
((?) Spence's method . . . 406 

III. The Determination of Protein 

in Crude Rubber . . . 407 
Vulcanised and manufactured rubber . 407 

B. Accessory Materials of the Rubber 

Industry ...... 409 

Substitutes ...... 410 

White substitute .... 410 

Brown substitute . . . .411 

Other organic accessories . . . 413 

Bitumen 413 

Pitch 413 

Solvent naphtha . . . .414 
Shale spirit ..... 414 
Petroleum naphtha .... 414 
Reclaimed rubber .... 414 
Organic colouring matters . -415 

Fabrics 415 

Inorganic accessories .... 415 

Sulphur . . . . . .415 

Sulphur chloride . . . .415 

Antimony sulphide . . . .416 



PAOK 



B. Accessory Materials of the Rubber 

Industry — Continued. 
Inorganic accessories — Continued. 
Vermilion .... 

Covering power 

C. The Analysis of Rubber Goods 

Special methods of analysis 
I. Preparation of the sample . 
Desiccation 
Incineration 
Total sulphur . 
Chlorine .... 
Sulphur combined with metals 
Carbonic acid . 
The direct isolation of filling 

materials 
Extraction with volatile solvent 
Determination of substitutes 
Resins insoluble in acetone 
Pitch and bitumen . 
The direct determination of 
antimony and mercury sul- 
phides . . . . . 
The direct determination of 
rubber .. 
General scheme of analysis 
Interpretation and statement of analy^ 

tical results ... 
The examination of cable insulation: 

and specifications for the same 
Miscellaneous notes on the analysis 
of rubber and of rubber goods 
Coefficient of vulcanisation 
Analysis of proofed fabrics 
Rubber solutions . 
Specific gravity 
Microscopic examination 



2. 
3. 
4- 
5- 
6. 

7. 
8. 

9- 

ID. 
II. 
12. 

13- 



14. 



D. Empirical Tests applied to R 



'bbei 



I. Chemical tests .... 441 

1. Dilute acids .... 441 

2. Alkalis 442 

3. Alcoholic alkali .... 442 

4. Saline solutions .... 442 

5. Chlorine 442 

6. Fatty and mineral oils . . . 442 

7. Resistance to oxidation . . 442 

II. Physical and mechanical tests . 443 

8. Dry heat test .... 443 

9. Superheated steam . . . 443 

10. Action of light .... 443 

11. Permeability . . . .443 

12. Resistance to pressure . . . 444 

13. Percussion test .... 444 

14. Insulation and breakdown voltage 444 

15. Resiliency 444 



439 
439 
439 
440 

440 
441 
Goods 441 



417 
417 

417 
418 
418 
418 
419 
419 
422 
422 
423 

423 
42s 
425 
426 
426 



427 

428 
429 

435 
437 



xxu 



CONTENTS 



PAOB 

D. Empirical Tests applied to Rubber Goods — 
Continued. 
II. Physical and mechanical tests — Contd. 

1 6. Abrasion ..... 444 

17. Tensile test 444 

18. Bending stress .... 447 

19. Washers for bottle-stoppers . . 447 
Gutta-percha and Balata .... 447 

((7) Gutta-percha ..... 447 
{b) Balata 45 1 

Liter.-iture 451 

Vegetable Tanning Materials. 

Preliminary Notes on the Estimation of 

Tannin ...... 452 

A. Non-gravimetric Methods of Tannin 

Analysis 453 

I. The Loewenthal - von Schroeder 

Method 453 

II. Procter and Hirst's Modification of 

the Loewenthal Method . . 458 

III. Appendix 463 

1. Estimation of moisture . . 463 

2. Estimation of sugary matters . 463 

B. The most recent Standard Gravimetric 

Method of Tannin Analysis, according 
10 the Regulations framed at the 
Conferences of the International As- 
sociation of Leather Trades Chemists 464 

I. Resolutions of Previous Conferences 

still in force ..... 464 

1. Sampling the bulk . . . 464 

2. Preparation of the sample for 

analysis ..... 465 

3. Preparation of the infusion . . 466 
Solution of extracts . . . 467 
Extraction of solid tanning 

materials .... 468 

II. Most recent Resolutions of the 

International Conferences at Brus- 
sels (1908) and Paris (1910) . . 469 
General directions .... 469 
Detailed official method of analysis 
adopted by the International 
Association of Leather Trades 
Chemists which is obligatory on 

all members 470 

Literature ...... 474 

Leather. 

I. Accessories to the Processes prior to ' 
Tanning ...... 475 

Water 475 

Depilatories 476 

Deliming, swelling, and bating materials 477 



PAGE 

II. Vegetable Tanning Materials and 

Tannin Infusions .... 478 

III. Mineral Tanning Materials . . 480 

IV. Other Tanning Materials and 
Accessories for Leather Dressing . 481 

Preserved ^g'g yolk .... 481 

Admixture of other oils . . . 482 
Tallow ...... 483 

Fish tallow . . . . .484 

Fish oils ...... 484 

Neat's-foot and bone oil . . . 488 
Moeilon and Dcgras. . . . 488 

Vaseline oils and mineral oils . . 493 
Soaps ...... 493 

V. Control of Working Conditions . . 493 
The estimation of nitrogen . . . 493 
Tan liquors ...... 495 

Acidity ...... 496 

Estimation of volatile and non-volatile 

acids ...... 497 

Spent tanning materials . . . 497 

VI. The Examination of Leather . . 498 
Sampling ...... 498 

(rt) Vegetable tanned leather . . 498 
Estimation of moisture . . . 498 
Estimation of mineral matter (ash) . 499 
Estimation of the fat ... 499 

Estimation of the loss on washing 

(Auswaschverlust) and of the • 

content of extractable tans and 

non-tans . . . . -499 
Estimation of hide substance and 

combined tannin . . . 500 
Estimation of sugar . . . • . 502 
Estimation of sulphuric acid and of 

lime 503 

Estimation of the specific gravity . 506 
Nature of the tannage . . . £o6 
Tannin penetration test (acetic acid 

test) 506 

Test of strength .... 506 
Water-absorption test . . . 507 
(J)) Chamois leather .... 507 
{c") Chrome leather .... 507 
Estimation of moisture . . . 507 
Estimation of mineral matter . . 507 
hstimation'of chromic oxide . . 508 
Estimation of alumina . . . 508 
Estimation of sulphuric acid and of 

alkalis 508 

Estimation of chlorides . . . 509 
Estimation of fat and free sulphur . 509 
Estimation of hide substance . . 509 

Literature 510 



CONTENTS 



XXlll 



Ink. 

A. General Survey 

B. Description of Different Classes of 

Inks. ..... 

I. Black Writing Inks . 

Normal inks .... 

German official classification of 

writing inks . 
New Prussian regulations 
The composition of English inks 
Qualitative examination of writing 

inks 

Schluttig's "stripe" method. 
Differential reactions 
Practical tests of writing inks . 

1. Determination of the darkening 

Capacity 
Acidity .... 
Proportion of iron 

2. The stability of the ink 

3. The fluidity and penetrating 

capacity of the ink and sticki- 
ness of the writing . 

4. Identification of different inks 



5" 

512 
512 
512 

512 
516 
516 

518 
518 

519 

520 

520 
522 
523 
523 



524 
525 



PAOS 



B. Description of Different Classes of 
Inks — Cojitinued. 

I. Black Writing Inks — Continued. 
Differentiation of inks in writing 

II. Copying Inks 

III. Coloured Writing Inks . 
Tests for coloured inks 

I. Blue and blue-black inks . 

II. Green and green-black inks 

III. Red and red-black inks . 

IV. Violet and brown inks 

V. Black inks 

IV. Drawing Inks 
Indian inks .... 
Sepia ..... 
Waterproof inks 

V. Printing Inks .... 

VI. Ticket and Stencilling Inks . 

VII. Marking Inks 

VIII. Typing Inks 

IX. Inks for Writing on Metals, Glass 
etc 

X. Sympathetic Inks . 

Literature 



525 
£27 

527 
528 
528 

529 

530 
530 
531 
532 
532 
533 
534 
534 
534 
535 
536 

536 
537 
538 



PART I I 



Sugar. 
Prefatory Note 

I. The Sugar Beet . 

A. Estimation of Sucrose 
Alcoholic extraction . 
Digestion methods . 



539 

539 
542 

544 
547 



((?) The warm alcoholic digestion 

method 547 

(J)) The warm aqueous digestion 

method ..... 548 

(t) The cold aqueous digestion 

method 549 

B. Estimation of Fibre or Juice and of 

Dry Substance .... 552 

C. Estimation of Invert Sugar . . 554 

(3) Gravimetric estimation of small 
quintiiies of invert sugar 
(0.5-1.0 per cent.) in presence 
of sucrose .... 555 

((5) Gravimetric estimation of 
larger quantities of invert 
sugar in presence of sucrose . 558 

(c) The gravimetric inversion 

method 561 



PAOB 

I. The Sugar Beet — Continued. 

C. Estimation of Invert Sugar — Contd. 

(r/) The volumetric estimation of 

invert sugar .... '63 
The estimation of invert sugar 
in beetroot .... 566 

D. Beetroot Seeds .... 567 

II. Beetroot Juice ^ Thin Juice^ and the Pro- 

ducts occurring in the Working up of 
Juice 568 

1. Beetroot juice, thin juice . . . 568 

A. Determination of Specific Gravity 569 

B. Estimation of Sucrose . . . 578 

(1) Gravimetric method . . 578 

(2) Volumetric method . . 579 

C. Estimation of Water and Non- 

Sugar ; Purity Quotient . . 587 

D. Estimation of Ash . . . 589 

E. Estimation of Invert Sugar . . 590 

F. Estimation of Alkalinity, Acidity, 

and Coagulability . . . 591 

G. Estimation of Colour . . . 592 

2. Waste-water, wash water, etc. . . 592 

3. Extracted slices and pressed slices ; 

dry slices and sugar slices . . 594 

4. Press mud, defecation mud . . 595 



XXIV 



CONTENTS 



PAGE 

I IF. Thick Juices, Syrups . . . . 596 

A. Determination of Specific Gravity . 596 

B. Estimation of Sucrose . . . 597 

C. Estimation of Water and of Non- 

sugar Constituents . . . 600 

D. Estimation of Ash .... 606 

E. Estimation of Invert Sugar . . 606 

F. Estimation of Raffinose . . . 607 

G. Estimation of Colour . . . 610 
H. Estimation of Alkalinity . . .610 

IV. .\fassecuites 610 

A. Estimation of Dry Substance and of 

Specific Gravity .... 610 

B. Estimation of Sucrose . . .612 

C. Estimation of Raffinose . . .612 

D. Estimation of Invert Sugar . . 612 

E. Estimation of Water . . . 6l2 

F. Estimation of Ash . . . .612 

G. Estimation of Alkalinity . . .612 
H. Estimation of Colour . . .612 
I. Estimation of the Content of Crystals 613 

V. Sugar (^Raw Sugar, Refined Sugar, 

After-products') 613 

A. Estimation of Sucrose . . . 613 

B. Estimation of Water and Non-sugar 614 

C. Estimation of Ash .... 614 

D. Estimation of Invert Sugar . . 614 

E. Estimation of Raffinose . . .615 

F. Estimation of Colour . . .615 

G. Estimation of Alkalinity . . . 615 
H. Examination for Sulphurous Acid . 616 
I. Estimation of the Content of Crystals 616 
K. Calculation of Yield (Rendement) 616 

VI. Molasses, Runnings, Mother Syrups .617 

A. Determination of the Specific Gravity 617 

B. Estimation of Sucrose . . . 619 

C. Estimation of Water and Non-sugar 

Substances 623 

D. Estimation of Ash .... 623 

E. Estimation of Invert Sugar . . 623 

F. Estimation of Raffinose . . . 624 

G. Estimation of Colour . .624 
H. Estimation of Alkalinity . . 624 

VII. Products obtained in working up 
Molasses ...... 624 

A. Calcium Sucrate and VVaste Liquors 624 

1. Calcium sucrate .... 624 
(a) Determination of specific gravity 624 
(//) Estimation of sucrose . . 625 

(c) Estimation of lime . . . 625 

(d) Estimation of purity . . 625 

2. Waste Liquors .... 626 
(a) Determination of specific gravity 626 
{/>) Estimation of sucrose . . 626 



PXOB 

VII. Products obtained tn working up 

Molasses. — A. Calcium Sucrate and 
Waste Liquors — Continued. 
2. Waste Liquors — Continued. 

(c) Estimation of potash . . 626 

(</) Estimation of nitrogen . . 627 

B. Strontianite and Products of the 

Strontia Process .... 627 

1. Strontianite ..... 627 
(ij) Estimation of moisture . . 627 
(J>) Estimation of the portion in- 
soluble in acid . . . 627 

(c) Estimation of oxide of iron and 

alumina ..... 627 

(ji) Separation and estimation of 
strontium and calcium car- 
bonates . . . . .627 

2. Ignited ore and residue . . 628 

3. White salt, brown salt, centrifuged 

salt and sucrate . . . 629 

4. Charred vinasse .... 630 
(a) Estimation of moisture . . 630 
(/^) Estimation of the portion in- 
soluble in water . . . 630 

(c) Estimation of total alkali salts 630 

(_d) Estimation of potassium chlor- 
ide. . . • . . 631 

(^) Estimation of potassium sul- 
phate . . . . .631 

(/) Estimation of potassium phos- 
phate 631 

{jg") Estimation of potassium car- 
bonate 631 

(//) Estimation of sodium carbonate 632 

C. Osmose Water .... 632 

D. Molasses Fodders .... 634 

1. Estimation of moisture. . . 634 

2. Estimation of sucrose . . . 634 

3. Estimation of fat . . . . 635 

4. Estimation of nitrogen . . .635 

VI n. Accessories 636 

A. Animal Charcoal .... 636 

1. Estimation of moisture . . . 636 

2. Estimation of carbon, sand, and 

clay ...... 636 

3.' Estimation of calcium carbonate . 636 

4. Estimation of calcium sulphate . 638 

5. Estimation of calcium sulphide . 639 

6. Estimation of organic matter . 639 

7. The mechanical analysis of char- 

coal 639 

8. Estimation of sucrose in spent 

animal charcoal . . . 639 

9. Estimation of phosphoric acid in 

animal charcoal lye . . . 640 



CONTENTS 



XXV 



PAGE 

VIII. Accessories — Continued. 

B. Strontianite and Strontium-contain- 

ing Manufacturing Products . . 640 

C. Limestone 640 

D. Defecation Lime (Burnt Lime) . 640 

E. Water 641 

F. Sodium Carbonate, Sodium Hydrox- 

ide, Hydrochloric Acid, Sulphuric 
Acid 642 

G. Saturation Gas, Flue Gases . .642 
H. Fuel 644 

IX. Products of the Cane Sugar Industry . 644 

I. The Sugar Cane .... 645 

Sampling 645 

Estimation of sucrose . . . 645 
Estimation of the dry substance . 647 
Estimation of the expressed cane 

(bagasse, megasse) . . . 647 

II. Factory Products .... 648 
Estimation of sucrose . . . 648 
Quotient of purity .... 650 
Estimation of the apparent purity of 

crude juice . . '. , 652 

Estimation of the reducing sugar . 652 

Literature 657 

Starch and Dextrin. 
I. Starch 659 

A. The Examination of Raw Materials 659 

1. Estimation of starch by washing 

out the raw material . . . 659 

2. Estimation of starch by chemical 

analysis ..... 659 
Estimation of sugar in potatoes . 660 
Estimation of the total solids of 

potatoes . . . .661 

The pentosans .... 661 

3. Polarimetric estimation of starch . 667 

4. Estimation of starch in potatoes 

by the specific gravity methods . 669 

B. The Examination of Different 

Starches ..... 670 

1. Potato starch . . . .671 

2. Rye, wheat, and barley starch . 671 

3. Oat starch .... 672 

4. Rice starch .... 672 

5. Maize starch .... 672 
Estimation of the content of water in 

starch 674 

Estimation of acid in starch . . 678 
Determination of the adhesiveness of 

starch ..... 679 

Examination of starch flour for 

impurities and adulterations . 679 



PAOE 

I. Starch — Continued. 

C. The Examination of the Waste 

Products ..... 680 

D. The Examination of the Auxiliary 

Raw Materials used in the Manu- 
facture of Starch . . . .681 

II. Dextrin 682 

A. The Examination of the Raw 

Materials 682 

B. The Examination of Auxiliary 

Raw Materials . . . .682 

C. Control of Working Conditions . 682 

D. Analysis of Dextrin . . . 683 

1. Estimation of the percentage of 

pure dextrin .... 683 

2. Estimation of water . . . 684 

3. The acidity of dextrin . . . 684 

4. The content of ash . . . 684 

5. The content of sand . . . 684 

6. Estimation of constituents soluble 

and ^insoluble in cold and hot 
water 684 

7. Estimation of the soluble starch . 685 

8. Estimation of the sugar . . 685 

9. Determination of the keeping 

quality and consistency of the 
concentrated solution . . . 686 

10. Determination of the viscosity . 686 

11. Chlorine 686 

12. Unchanged starch . . . 687 

13. Scorched glutin .... 687 

Literature 687 

Alcohol, Potable Spirits, and Liqueurs. 

I. The Examination of Water . . . 688 

II. The Examination of Raw Materials . 688 

A. Amylaceous Materials . . . 688 

1. The polarimetric estimation of 

starch in cereals . . . . 689 

2. The estimation of starch by hy- 

drolysis with diastase . . 690 

3. The estimation of starch by fer- 

mentation 692 

B. Molasses 692 

1. The estimation of fermentable 

sugars 692 

2. The fermentative capacity . . 693 

C. Other Raw Materials . . .695 
Wort extract and spirit yield of mash- 
ing materials .... 695 



XXVI 



CONTENTS 



PAGB 

II. The Examination of Raw Materials — 

Continued. 
D. The Examination of Barley and 

Malt 696 

1. Barley 696 

2. Malt 697 

1. The determination of the dias- 

tatic power of malt (Lintner 

value) 697 

2. The determination of the lique- 

fying capacity of malt . . 698 

3. The estimation of acidity . . 699 

4. The estimation of moisture . 699 

5. The cold water extract . . 700 

III. The Examination of the Wort . . 700 

1. The iodine test .... 700 

2. The estimation of the total solids in 

solution ..... 701 

3. The estimation of "apparent mal- 

tose and dextrin " . . . . 702 

4. The acidity 704 

IV. The Examination of the Fermented 
Wort (Wash) 704 

1. The presence of diastase . . . 704 

2. Microscopic examination . . . 705 

3. The degree of fermentation, " At- 

tenuation " . . . . . 705 

4. The estimation of maltose and 

dextrin ...... 706 

5. The acidity 707 

6. Estimation of alcohol . . . 707 

7. The total nitrogen and the soluble 

nitrogen 708 

8. The examination of fermented 

molasses washes .... 708 

V. Alcoholometry 709 

VI. Denatured Alcohol . . . .713 

A. The Examination of Wood Naphtha 715 
I. Bromine decolorisation . . 715 
:. The methyl orange alkalinity test 715 

3. The estimation of methyl alcohol. 716 

4. The estimation of acetone . . 716 

5. The estimation of esters . . 717 

B. The Estimation of Methyl Alcohol 

in Ethyl Alcohol .... 717 

C. The Estimation of Ethyl Alcohol in 

Fusel Oil .... 



VII. Potable Spirits and Liqueurs 

A. Alcoholic Strength . 

B. Secondary Constituents . 

1. Total acidity 

2. Volatile acidity . 

3. Total solids and ash 



PACK 



720 
720 
720 
722 
723 
723 
723 



VII. Potable Spirits and Liqueurs — Contd, 




Examination of the distillate 


724 


4. Acidity of the distillate 


7 -'4 


5. Esters 


724 


6. Furfural .... 


725 


7. Aldehydes .... 


725 


8. Higher alcohols . . . , 


726 


The Allen-Marquardi method 


726 


The Ruse-Herzfeld method . 


728 


The sulphuric acid (colorimetric^ 




method .... 


733 


Beckmann's nitrite method . 


734 


Potable spirits .... 


735 


I. Whisky .... 


735 


2. Brandy .... 


735 


3. Rum .... 


735 


4. Gin 


736 


5. Kirschwasser . 


736 


Liqueurs, bitters, and cordials . 


737 


I. The estimation of sugar ir 




liqueurs .... 


739 


2. Colouring matters . 


740 


Literature ..... 


• 740 



Vinegar. 
Introduction ...... 

A. The Analysis of the Raw Materials 

of the Vinegar Industry . 

1. Malt 

2. Barley, rice, rice grits, maize grits 

3. Flaked maize .... 

4. Glucose 

5. Raw sugars, invert sugar, molasses 

6. Acetic acid .... 

7. Caramel ..... 

8. Sulphuric acid 

B. The Analysis of V^ineg;ir . 

1. The specific gravity . 

2. Total acid .... 

3. Alcohol 

4. Heavy metals .... 

5. Arsenic 

6. Cyanogen compounds 



C. The Further Examination of \'inegar 748 

749 
750 
750 
750 

751 
751 
751 
751 

752 

753 
752 



1. OeVermination of free mineral acid 

2. Fixed organic acids 

3. Total solids 

4. Ash .... 

5. Total phosphoric acid 

6. Nitrogen .... 

7. Potassium hydrogen tartrate 

8. Foreign pungent materials 

9. Polarisation 

10. Preservatives . 

11. Foreign colouring matters 



741 

744 
744 
744 
745 
745 
745 
745 
747 
747 
747 
747 
747 
747 
748 
748 
748 



CONTENTS 



XXVll 



C. The Further Examination of Vinegar — 
Continued. 
12. Aldehyde, glycerol, dextrin, fixed 

and volatile acid . . . -753 
Detection of misdescription . • . 753 

Literature 754 



Wine. 



Prefatory note 



The Analytical Examination of Wine . 

A. The Drawing, Labelling, Storage 

and Dispatch of Samples of Wine 
for Chemical Analysis, and General 
Remarks (German Regulations) . 

B. Official Methods of Analysis 

(German Regulations) . 
I. Determination of the specific 

gravity ..... 
Estimation of the alcohol . 
Estimation of the extract (content 

of extractives) .... 
Estimation of mineral constriuents 
Estimation of the sulphuric acid in 

red wines ..... 
Estimation of the free acids (total 

acids) ..... 

Estimation of the volatile acids . 
Estimation of the non-volatile 

acids ...... 

Estimation of the glycerol . 
Estimation of the sugar 

11. The rotatory power (polarisation) 

12. Detection of impure glucose by 
polarisation . . . . 

Detection of foreign colouring 
matter in red wines . 
Estimation of the total tartaric 
acid, free tartaric acid, tartar, 
and tartaric acid combined with 
alkaline earth metals . 
Estimation of sulphuric acid in 
white wines . . . . 

16. Estimation of sulphurous acid 

17. Estimation of saccharin 

18. Detection of salicylic acid . 

19. Detection of gum arable and 
dextrin . • . . . 
Estimation of tannin . 
Estimation of chlorine 
Estimation of phosphoric acid 
Detection of nitric acid 

24, 25. Detection of barium and of 

strontium 

26. Estimation of copper . 



2. 

3- 

4- 
5- 



7- 



9- 

10. 



13- 



14. 



15- 



20. 

21. 

22. 
23. 



755 
756 



756 

758 

758 
758 

759 

764 

765 

765 
765 

766 
766 
767 

771 

772 
774 



776 

779 
779 
780 
782 

782 

783 
784 

784 
784 

785 

785 



PAOE 

L The Analytical Examination of Wine — 
Continued, 
C. Other Methods of Analysis . . 786 

27. Detection of foreign colouring 
matter in white wines. . . 786 

28. Estimation of succinic acid . . 786 

29. Estimation of lactic acid . . 787 

30. Estimation of malic acid . . 790 

31. Detection and estimation of citric 
acid 791 

32. Estimation of the volatile esters 

of wine 792 

33. Detection and estimation of 

aldehydes 793 

34. Estimation of dextrose and Isevu- 
lose in musts and in sweet wines 793 

35. Detection and estimation of 
mannitol ..... 794 

36. Detection of liquorice juice . 794 

37. Detection of dulcine . . . 794 

38. Detection of abrastol (asaprol) . 795 

39. Estimation of nitrogen . . 796 

40. Detection and estimation of boric 
acid 796 

41. Detection and estimation of 
fluorine compounds . . . 797 

42. Detection of hydrogen sulphide . 799 

43. Estimation of lime, magnesia, 
alkali-metals, silicic acid, iron, 
alumina, manganese, heavy 
metals, and arsenic . . . 799 

44. Detection of oxalic acid . . 799 
n. The Judging of Wines from the 

Results of the Chemical Examination 800 



The recognition of sugared 


wines 


800 


"Marc "wines. 




801 


Yeast wines 




801 


Raisin wines (basis wines) 




801 


The addition of fruit must 


and fruit- 




wine to grape-wine 




802 


Boric acid in wine 




802 


Soluble fluorine compounds 


in wine . 


802 


Salicylic acid in wine 




803 


Glycerol in wine 




803 


Sodium salts in wine 




803 


Volatile acids in wine 




804 


The judging of sweet wines . 




804 


Literature .... 




805 


Brewing Materials and Beer. 




The Brewing Process 




806 


L Brewing Materials 




808 


■ A. Water .... 




808 


B. Malt .... 




809 


I. Extract 




809 


2. Tint .... 




811 



XXVIU 



CONTENTS 



I. Brewing MaUrials — Continued. 
B. Mall— r(7w//n«/(/. 

3. Moisture 

4. Diastaiic power 

5. Cold water extract 

6. ^fodification 

7. "Saccharification" time 

8. Nitrogen 



9. Soluble uncoagulable albuminoids 815 



10. Physical examination 
Growth of acrospire 
Results of analysis . 
Brown and Crystal malts 

1. Extract 

2. Tint 
Black barle3's and malts 

1. F.xtract 

2. Tint 

C. Caramel . 

1. Extract 

2. Tint 

3. Ash ... 

4. Iron ... 

5. Deportment with beer 

D. Flaked maize and rice 

1. Extract 

2. Moisture 

3. Oil . . . 

E. Grits and raw grain 

F. Barley . 

1. Moisture 

2. Nitrogen 

3. Starch . 

4. Weight of skins . 
The physical examination 

5. Germination test . 

G. Raw Cane Sugar . 
H. Invert Sugar . 

1. Albuminoids 

2. Ash 

3. Brewers' extract and water 

4. Sucrose, dextrose, and Ixvulose 

5. Unfermentable carbohydrates 
I. Glucose and other Starch Sugars 
K. Hops 



PAOE 



811 
811 
814 
815 
815 
815 



of barley 



816 
816 
817 
817 
817 
818 
818 
818 
818 

818 

818 

818 

818 

818 

818 

819 

819 

819 

819 

819 

820 

, 821 

821 

. 821 

. 821 

, 821 

.821 

822 

. 823 
. 823 
. 823 
. 824 
. 824 
. 827 
. 827 
. 828 



1. Estimation of hard and soft resins 828 

2. Direct estimation of antiseptic 

power of hops .... 829 

3. Estimation of moisture . . 830 

4. Detection of " sulphuring" . . 830 
Detection of free sulphur . . 830 
Estimation of free sulphur . . 831 

5. Physical examination of hops . 831 
Interpretation of results of the 

chemical analysis of hops . . 832 



II. Beer . 

1. Original gravity 

2. Alcohol 

3. Extract . 

4. Forcing test . 



PACE 

. 832 
. 832 
. 835 
. 835 
. 835 



Estimation of arsenic in brewing 

materials and beer .... 836 
Literature 837 

Paper. 

The determination of mineral contents . 838 
The microscopic examination of the fibrous 

constituents of paper .... 840 
Preparation of the paper for examination 840 



Mechanical wood 


. 842 


Wood cellulose . 


. 842 


Jute .... 


. . 842 


Straw cellulose . 


. 842 


Esparto cellulose 


. 843 


Linen 


. 843 


Hemp 


. 843 


Cotton 


. 843 


The degree of lignification of 


wood cel- 


lulose 


. 844 


Klemra's method of examination . . 845 


The differentiation of sulphite and soda 


wood cellulose . 


. 846 


The macroscopic determination 


of mechani- 


cal wood . 


. 846 


Determination of the hardness 


of size in 


paper 


. . . 847 


The examination of size . 


. 847 


Animal size (gelatin) 


. 847 


Rosin size 


• 849 


Casein size 


. . . 851 


Starch 


. . . 852 


Viscose 


. 852 


Wax, paraffin, stearine, fat, oil . .853 


The determination of the rate of filtration 


and separating capacity 


of filtering 


paper 


. . . 853 


Rate of filtration . 


. . . 853 


Separating capacity 


. . . 854 


The absorbency of papers 


. • . 855 


• The strip test . 


. . • 855 


The zone test . 


. 856 


Imperviousness to air . 


. 856 


The detection of free chlorine 


and of free 


acid .... 


. . . 857 


Impurities in papers injurious 


to metals . 858 


Loss of colour in paper 


. 859 


Other physical properties of p 


aper of im- 


portance in paper testing 


• 859 


Opacity 


. 860 


Bulk .... 


. 860 



CONTENTS 



XXIX 



Other physical properties of paper of im- 
portance in paper testing — Continued. 
Surface ...... 86i 

Tenacity . . . . . .861 

Elasticity 861 

Breaking weight and bursting strain . 862 

Literature 863 

Textile Fibres. 

I. The more important Reagents and 

Operations employed in the Testing 

of Textile Fibres .... 864 

1. Iodine solution and sulphuric acid 

mixture ..... 864 

2. Zinc chloride iodine solution . 865 

3. Reagents used for the identification 

of lignified fibres . . . 865 

4. Ammoniacal cupric oxide . . 866 

5. Ammoniacal nickel solution . . 866 

6. The separation of fibre bundles into 

ultimate fibres .... 866 

7. The preparation of thin cross- 

sections . , . . _ . 867 

II. The Chemical Examination of Textile 

Fibres 867 

1. Characteristic colorations with 

dyestuffs 867 

2. Action of solutions of different salts 868 

3. Action of alkaline solutions . . 868 

4. Action of acids, etc. . . . 869 

A. Methods of Distinguishing Animal 

and Vegetable Fibres . . .870 

1. Molisch's method .... 870 

2. The behaviour of fibres towards an 

8 per cent, solution of sodium or 
potassium hydroxide . . . 870 

3. The rosaniline reaction . . . 870 

4. Behaviour towards boiling nitric 

acid . . . . . .871 

5. Action of a " nitrating mixture " . 871 

6. Behaviour of the fibres during 

burning 871 

7. Manca's oleic acid and sulphuric 

acid test 871 

B. Methods of Distinguishing Different 

Fibres from each other . . . 872 

1. Wool and silk . . • . 872 

2. Cotton and linen .... 872 

3. Flax and hemp .... 873 

4. Jute from linen and hemp . . 873 

5. Cotton, and kapok . . . 875 

C. Quantitative Estimation of Indi- 

vidual Fibres in Fibre Mixtures . 875 

1. Cotton and wool .... 875 

2. Silk, wool, and cotton . . . 877 



PAGE 

II. The Chemical Examination of Textile 

Fi bres — Couiunced. 

D. The Examination of Weighted Silk. 878 
Qualitative examination . . . 878 
Quantitative examination . . . 880 

1. Estimation of water . . . 880 

2. Weighting materials soluble in 

water 880 

3. Petroleum spirit or ether extract 880 

4. Action of hydrochloric acid . 881 

5. Action of alkalis . . . 881 

6. Estimation of ash . . . 881 

7. Colouring matters . . . 881 
Quantitative estimation of the weight- 
ing materials in dyed silk . . 882 

Quantitative estimation of the weight- 
ing materials in black silk . . 884 

Stripping methods .... 885 
(rt) Hydrofluoric acid method . 885 
((J) Hydrochloric acid method . 887 
(0 Oxalic acid method . . .887 

(d) Sulphuretted hydrogen alkaline 

sulphide method . . . 888 

(e) Estimation of the boiling-off of 

silk 889 

E. Analysis of Shoddy, etc. . . . 889 
Quantitative analysis . . . 890 
Qualitative examination . . . 890 

F. TheDegreeof Bleaching of Cellulose 891 

G. Tests for Oxycellulose and Hydro- 

cellulose ..... 891 

III. The Microscopic Examination of 

Textile Fibres .... 892 

IV. Mercerised Cotton and Artificial Silk 894 
Mercerised cotton ..... 894 
Artificial silk ..... 897 

Chardonnet, Lehner, Besangon, 

Meteor or Frankfurt silk . . 898 

Glanzstoff (Pauly silk) . . . 899 

Viscose silk ..... 900 

Acetate silk ..... 900 

Vandura silk (gelatin silk) . . 900 

Clement's method of examination . 901 

Clement's method for the differentiation 

of natural and artificial silk . . 902 

Finishing Materials .... 903 

Substances used in finishing . . . 903 
The chemical examination of finishing 

materials 903 

Literature 909 

Inorganic Colours. 

I. Naturally occurring White Auxiliary 
Colours — 
Adulterants and substrata . . .910 
Calcium carbonate . . . .911 



XXX 



CONTENTS 



PAGE 

I. Naturally occurring White Auxiliary 

C o 1 our s — Continued. 
Adulterants and substrata — Continued. 
Quicklime . . . .911 

Gypsum . . . . . .912 

Barytes 913 

White clays 915 

II. White Pigments . . . .915 

White lead 915 

White lead substitutes . . . 921 
Zinc white ..... 922 
Lithopone 924 

III. Grey Pigments . . . .933 

Slate grey 933 

Zinc sulphide grey .... 933 
Zinc grey 933 

IV. Yellow Pigments . . . .933 
The yellow ochres .... 933 
Siennas 935 

The examination of mineral colours for 

arsenic ...... 935 

Artificial ochres .... 936 

Realgar ...... 936 

Orpiment ...... 936 

Naples yellow ..... 936 

Cassel yellow 938 

Tungsten yellow .... 938 
Litharge and massicot . . . 938 
Uranium yellow .... 939 
Cadmium yellow .... 939 
Cadmium orange .... 939 
Cobalt yellow (aureolin) . . . 943 

Nickel yellow 945 

The yellow chromium pigments -945 

Chrome yellow .... 945 

Chrome orange 946 

Chrome red ..... 946 

Valuation of the yellow and red 
chromium colours and of the raw 
materials used in their preparation 947 
(a) Examination of potassium chro- 

mate ...... 947 

(/') Examination of chrome yellow . 947 
{c) Examination of chrome orange 

and chrome red .... 950 

Zinc yellow 951 

Barium yellow ..... 952 
Strontium yellow .... 952 

V. Red Pigments ..... 953 
{a) Naturally occurring red pigments . 953 

Red ochres and other red mineral 

colours 953 

(J)') Artificial products .... 953 
English red ..... 954 
Red lead (minium) .... 957 



V. Red Pigments — Continued, 
(h) Artificial products — Continued. 

Brilliant scarlet 
Vermilion (cinnabar) 
Antimony vermilion . 
Cadmium red . 
Chrome red 



VI. Blue Pigments . 
Prussian blues . 
Blue copper colours . 
Blue cobalt colours . 

Smalts .... 
Cobalt blue . 
Cceruleum 
Ultramarine .... 

I. The Analysis of Raw Materials 

1. Clay. 

2. Silica 

3. Sulphur . 

4. Sodium carbonate 

5. Sodium sulphate 

6. Rosin and pitch 

II. Control of Working Conditions 
Supervision of the burning process 

and working up of the raw 
product 985 

III. The Examination of the Finished 
Ultramarine .... 988 

1. Colouring power . . . 988 

2. Fineness ..... 988 

3. Examination for free sulphur . 989 

4. Examination for alum resistance 989 

5. Examination for use in calico 

printing ..... 989 

6. Examination for use as a lacquer 990 

IV. Analysis of Ultramarine . . 990 

1. Preparation of the raw ultra- 

marine for analysis . . . 990 

2. Estimation of silica, clay residue, 

and total sulphur . . . 991 

3. Estimation of alumina and 

sodium oxide . . . .991 

4. Examination for additions in- 

soluble in acid . . . 992 
' r Properties of technical importance 

in painting .... 993 

Behaviour of ultramarines in mix- 
tures 993 

Fastness to zinc white . . . 993 

VII. Violet Pigments .... 994 

Cobalt violet 994 

Manganese violet .... 994 
Mineral violet .... 994 
Violet and red ultramarine . . 995 



961 
962 
965 
965 
967 

96S 
968 

975 
976 

977 
977 
979 
979 
981 
981 
983 
983 
984 

985 
985 

985 



CONTENTS 



XXXI 



PAOE 

VIII. Green Pigments .... 995 

(a) Natural products . . . 995 

Green earths (seladonite) . . 995 

((5) Artificial green pigments . . 999 

Cobalt green (Rinmann's green) . 999 

iVIanganese green . . . 1000 

The green chromium pigments . 1000 

Chrome oxide green . . . looo 

Guignet's green .... looi 

Chromium phosphate greens . 1003 

Arnaudon's green . . . 1003 

Schnitzer's green . . . 1004 

Mathieu Plessy's green . . IC04 

Ultramarine green . . . 1004 

(c") Green mixture - pigments of 

chrome yellow and Paris blue 1004 
Chrome green .... 1004 

Zinc greens 1005 

((/) The green copper pigments . 1006 
X. Imitation native malachite 

greens ..... 1006 
Mountain green . . . 1006 
Lime green . . . - . 1006 
Bremen green .... 1006 
Brunswick green • . . ico6 
Erlau green .... 1007 
BoUey's green .... 1007 
Gentele's green . . . 1007 

Eisner's green .... 1007 



PAGE 



VIII. Green Pigments — Continued. 

{d') The green copper pigments — Contd. 



2. Verdigris 
Casselmann's green . 
Saxon verdigris 

3. Arsenic greens 
Scheele's green 
Emerald or Schweinfurth green 
Neuwied green 



IX. 



Brown Pigments 



(minera! 



(a) Natural products . 

Umber, umber brown 

brown) .... 
(Jj) Artificial products 

Berlin brown .... 

Florentine brown 

X. Blaclc Pigments 

Graphite 

Appendix 

I. Bronze pigments . 
Tungsten bronze 

II. Lakes from artificial dyes 
Lake precipitants for acid dyes 
Lake precipitants for basic dyes 
Lake bases ('substrata) . 
Examination of the dyes . 
Examination of the substratum 

Literature ..... 



1007 
1007 
1007 
1008 
IC08 
1008 

lOIO 

lOII 
lOII 

lOII 
I0I2 
IOI2 
I0I2 

I0I2 
I0I2 
IOI3 
IOI3 
IOI4 
IOI4 
IOI4 
IOI5 
IOI5 
IOI5 
IOI6 
IOI7 



Appendix 1019 

Index of Subjects 1083 

Index of Names 1114 



MINERAL OILS 

By Prof. D. HOLDE, Ph.D., Divisional Director of the Royal Testing Laboratory, 
Gross-Lichterfelde, Berlin, English translation revised by the late J. Lewko- 
WITSCH, M.A., Ph.D.i 

CRUDE PETROLEUM, NAPHTHA, BURNING OILS, 
PARAFFIN WAX, ASPHALT, SHALE OIL, 
AND LIGNITE TAR. 

^.— CRUDE PETROLEUM. 

Crude Petroleum is usually dark brown or black in colour, but occasion- 
ally lighter-coloured varieties (pale yellow to reddish-brown) are met 
with. According to the filtration hypothesis of D. Day, the lighter 
colour of certain crude oils is to be attributed to the percolation of the 
oil through subterranean layers of argillaceous shale, which absorb the 
colouring matter. If the crude oil is allowed to percolate upwards 
through a column of fuller's earth in a tube, fractionation takes place 
to a certain extent, paraffin hydrocarbons accumulating in the lighter 
fraction at the upper end, and heavy, unsaturated hydrocarbons at the 
lower end of the tube. According to Hofer's view, however, the filtra- 
tion hypothesis is not substantiated by geological observations. 

Two chief types of crude oil must be differentiated : — (i) Crude oils 
rich in naphthenes, with a paraffin-wax content of less than i per cent, 
containing, as a rule, very small quantities of low-boiling fractions 
(benzine and burning oils), and rich in high-boiling lubricating oils 
which do not solidify readily ; (2) crude oils containing less naphthenes, 
with a paraffin-wax content of 3-8 per cent., and yielding considerable 
quantities of benzine, burning oil, and light, mobile lubricating oils. 
Bustenari oil, however, notwithstanding its very low paraffin-wax 
content, yields considerable quantities (25 per cent.) of benzine. 

^ The Editor is indebted to Mr J. S. S. Brame, Lecturer on Fuel, The Sir John Cass 
Technical Institute, for very kindly reading the proofs of this section, the MSS. of which had 
been revised by the late Dr Lewkowitsch. — C. A. K. 

Ill A 



5 MINERAL OILS 

American, Galician (Boryslaw and Tustanowice), and Roumanian 
crude oil (from Campina) form the chief source of good paraffin wax 
(for candles), burning oil, and petroleum benzine. 

Most of the lubricating oils prepared from American, Galician, and 
Roumanian crude oils have a higher solidifying point (about o ) than 
Russian oils. A few Galician oils, e.g. that of Grosno, and a large 
proportion of the Roumanian oils, namely, the oils of Bustenari, Moreni, 
and Tintca, making up 70 per cent, of the Roumanian production, also 
yield lubricating oils useful for lubricating engines, railway carriages, 
etc., on account of their low solidifying point, suitable viscosity, and 
high flashing point. For cylinder oils the highly viscous, salve-like 
American products have proved the most suitable. The crude 
petroleums from Java, Borneo, and Sumatra are noted for the 
considerable amounts of low-boiling hydrocarbons useful as motor oil. 
The crude German oils are mostly deep brown or black and somewhat 
viscous ; those occurring in Alsatia arc suitable for the preparation of 
benzine, burning oil, easily solidifying lubricating oils, "cleaning oils," 
gas oils, and asphalt ; recently, also, paraffin wax has been extracted 
from them. The Hanoverian oils, especially the heavy oils from 
Wietze, yield lubricating oils, but no paraffin wax, and but very little 
benzine ; they contain, however, notable amounts of asphaltic substances. 
In addition to the products enumerated above there are obtained, from 
crude petroleums, transformer oils, and the still residues sold as Fuel 
oil (Masut), Goudron, Asphalt, coke for electrodes, etc. 

The world's production of crude petroleum in 191 2 was 46 million 
tons, as compared with a production of 1050 million tons of coal. It is, 
however, to be remembered that the calorific value of crude petroleum 
is 1 1,000-1 1,100 Cal. per kilogram as against 7000-7500 Cal. for coal, and 
only 4500-5000 Cal. for air-dried lignite. The distribution of the 
world's production in 191 2, expressed as a percentage of the total, was 
as follows: — United States 6325, Russia 19-37, Mexico 471, Galicia 
2-43, Roumania 370, East Indies 3-09, India 2-03, Germany 0-28. 

L CHEMICAL COMPOSITION. 

Crude petroleum consists chiefly of hydrocarbons of various boiling 
points, which do not belong to the lower boiling aromatic series 
(difference from coal-tar hydrocarbons). The oils arc not dissolved 
by sulphuric acid, whereas the heavier oils are partially converted into 
soluble sulphonic acids. Aromatic hydrocarbons (benzene and the 
higher homologucs) occur in small quantities in certain petroleums. 
The chemical nature of the viscous lubricating oils of petroleum is still 
unknown. Benzine, burning oil, gas oil, and paraffin wax consist, in 
the case of Pennsylvanian petroleum, mainly of hydrocarbons of the 



CRUDE PETROLEUM 3 

methane series, C^^H.,^^^^. In the case of Russian petroleum 80 per 
cent, consists of naphthenes, i.e. alicyclic polymethylenes, such as: — 

pentamethylene, CH., . CH.^ . CH., . CH., . CH., ; 

I " "^ ^ " I 

hexamethylene, CH., . CH., . CH., . CH., . CH., . CH., ; 

I I 

methyl hexamethylene ; etc. The high-boiling fractions of the Russian 
oils consist essentially of polynaphthenes (perhaps hydrodiphenyls). 
The naphthenes resemble the paraffin rather than the benzene hydro- 
carbons in their chemical behaviour ; they are not acted upon by 
permanganate, or by concentrated sulphuric acid, but yield sub- 
stitution products on treatment with chlorine and bromine, and even, 
though with greater difficulty, with dilute nitric acid ; concentrated 
nitric acid converts hexanaphthene into adipic acid, pentamethylene into 
glutaric acid. Zelinsky has succeeded in preparing synthetically high- 
boiling naphthenes — viz., cycloeikosan, C^qH^q, and cyclotessaracontane, 
Qo^so (melting point 1 18°), starting from the methyl ester of sebacic 
acid. As these experiments demonstrate the great tendency of the 
naphthenes to polymerise, Charitschkoff doubts whether the high-boiling 
viscous fractions of Russian petroleum consist of naphthenes, as is 
generally assumed. In the German, Galician, and Roumanian 
petroleums, the relative proportions of methane hydrocarbons and 
naphthenes vary according to the special localities in which the oils 
are found. In Galician and Roumanian oils notable quantities of 
unsaturated hydrocarbons occur, and in the latter aromatic hydro- 
carbons also. In some crude oils (especially those from Texas) 
secondary products occur in small quantities, such as pyridine bases, 
probably resulting from the decomposition of marine animals, according 
to the Hofer-Engler theory of the origin of petroleum, sulphur com- 
pounds such as mercaptans and organic sulphides (especially in Ohio 
oils), and oxygenated and sulphurised asphalt. The hydrocarbons of 
Texas oil belong chiefly to the series C^^H^,^,^, containing a double 
polymethylene ring, whilst in Ohio oil members of the series C^H2„^2' 
C^Hg,^, and C^Jr[^^^_^ are found. In Californian petroleums up to 15 per 
cent, of nitrogen compounds, containing 2 per cent, of nitrogen, are 
found, as also benzene, toluene, xylene, naphthalene, phenanthrene 
and anthracene. In the crude oil from the Santa Barbara County even 
members of the C^Ho„ « series were found ; this oil is remarkable for 
its high viscosity and specific gravity. The heavy Wietze oil is rich 
in asphalt. Engler and Jezioranski ^ showed that the fractions of 
Galician, Russian (Bibi-Eybat), and Pechelbronn oils boiling above 

1 Ber., 1895, 28, 2501. 



4 MINERAL OILS 

2CXd' dissolve almost completely in concentrated sulphuric acid, and 
contain on an average 87 per cent, of carbon (as against S57 per cent, 
in the olefines) ; hence they would appear to contain considerable 
quantities of more unsaturated hydrocarbons. In the case of Pennsyl- 
vanian petroleum, only 35 per cent, of the fractions boiling over 
200' dissolve in concentrated sulphuric acid. 

In the following Table the results obtained by the above authors are 
collated : — 

Table i. 



Crude oil from 


C per cent. 


11 per cent. 


per cent. 


Galinii .... 

Baku 

Alsalia .... 
Pennsylvania 


86-18 
86-21 
85-38 
86-10 


13-82 
13-49 
12-68 
13-90 


0'-30 

1-94 



The fractions boiling below 200^ contain principally saturated 
compounds of the methane and naphthene series. The elementary 
composition of crude oils from various sources varies within the follow- 
ing limits: — Carbon, 79-5-887; hydrogen, 9-6- 14- 8 ; oxygen, oi-6-9; 
nitrogen, o-02-i-i ; and sulphur, 0-OI-2-2 per cent. 

The following methods serve for the recognition and separation of 
the several groups of the constituents of petroleum : — 

1. Acidic constituents (naphthenic acids, phenols) are extracted by 
dilute sodium hydro.xide. 

2. Nitrogen compounds (homologues of pyridine, etc.) are extracted 
by dilute mineral acid. 

3. Unsaturated aliphatic hydrocarbons are extracted by sulphuric 
acid. 

4. Aromatic hydrocarbons are detected by nitration, 

5. Unsaturated cyclic hydrocarbons are separated b}' the Nastjukoff 
test (p. 8G). 

II. SPECIFIC GRAVITY AND COEFFICIENT OF EXPANSION. 

The specific gravity of crude petroleum varies from o 730-0-970 ; thus 
Pennsylvanian oil has a gravity of o-8i6;Baku oil, 0-882; Ohio oil, 
0887; East Galician oil, 0-870; heavy Wietze oil, 0-955. ^'^ one case 
Engler found a sp. gr, of almost i^o. 

A low specific gravity indicates a high proportion of benzine and 
burning oil ; a high specific gravity, on the other hand, indicates a notable 
proportion of high-boiling fractions and of asphalt. The specific gravity, 
although giving very little indication as to the source of a petroleum, 
may serve as a useful guide in the classification of oils of known origin, 
and has a considerable commercial importance for purposes of com- 



CRUDE PETROLEUM 5 

parison and identification, inasmuch as the specific gravity forms the 
simplest means of controlh'ng deliveries of oil. 

The determination of the coefficient of expansion of crude oils is of 
importance for the correction of the specific gravity determined at 
various temperatures to the normal temperature (15° or 20^), as also for 
the calculation of the expansion of the oil in the storage vessels and 
stills. 

The coefficient of expansion (a) of Pennsylvanian oil is 0-000840, 
that of Russian oil 0-000817 (of Wietzeoil 0-000647) ; hence it decreases 
as the specific gravity rises. The values for a series of oils are given in 
the subjoined Table. 

Table 2. 



Source. 


Sp. gr. 


ax 1,000,000. 


Canada ..... 

Alsatia 

11 ..... 

West Galicia .... 
Wallachia 


0-828 
0-829 
0-861 
0-885 
0-901 


843 
843 
858 
775 
748 



Zaloziecki and Klarfeld found an exceptionally high coefficient of 
expansion (about o-ooi) in the case of Galician crude oil from Boryslaw 
and Tustanowice. 

The determination of the specific gravity and coefficient of expansion 
of crude oils is carried out as described in the section on " Lubricants " 
(this Vol., pp. 61 and 6t,). 



III. DETERMINATION OF CONTAINED WATER. 

1, A method much used in oil refineries, but not universally 
applicable, is to place a measured quantity of crude oil, say 200 c.c, 
in a 500 or looo c.c. stoppered cylinder, best constricted at the bottom 
and graduated. Two to four times the volume of petroleum spirit or of 
benzene are added, and the whole warmed and shaken. After settling, 
the water content is read off; but as emulsions are readily formed and 
the reading is thus rendered indistinct, it is usual to take only 70 per 
cent, of the volume read off as water. The method of shaking with 
petroleum spirit is not applicable to oils which are rich in asphalt, as 
the latter is precipitated by petroleum spirit to some extent ; in this 
case benzene must be used, which, however, readily leads to the 
formation of emulsions. 

2. A method which is universally applicable for the determination 
of water consists in the distillation of the oil with xylene. According to 
Hofmann and J. Marcusson 100 g. of the crude oil (or 50 g. if the water 
content is high) are mixed with 100 c.c. of xylene, which has been 



6 MINERAL OILS 

previously saturated with water by shaking, and distilled in a 600 c.c. 
flask containing fragments of pumice, until 80-90 c.c. have passed 
over. The distillate is collected in a graduated cylinder which is 
constricted at the bottom. After rinsing out the condenser tube with 
xylene, and detaching any drops of water adhering to the sides of the 
cylinder, the quantity of water can be read off. 

M. Wielezynski ^ uses a centrifuge to separate the water, the centri- 
fuge being heated by a steam-jacket in the case of thick oils. 
Mechanical impurities are, however, separated together with the water, 
and the separation is not always satisfactory. Other methods of a 
chemical character have been proposed, such as the alteration in the 
titrc of X/io hydrochloric acid on shaking with the oil, due to the 
dilution by the water present;- the measurement of the acet)-lene 
evolved when calcium carbide is allowed to react with the oil, and of 
the hydrogen evolved when sodium is brought into contact with an 
ethereal solution of the oil."^ None of these proposals can be 
recommended. 

IV. DETERMINATION OF MECHANICAL IMPURITIES. 

Qualitative Exaniiiiation. — Mechanical impurities are detected by 
shaking 2 c.c. of oil with 40 c.c. of benzene, and allowing to settle for 
several hours. 

Quantitative Determination. — From 5-10 g. of the well-mixed oil are 
weighed out and dissolved in 100-200 c.c. of benzene. After standing 
for some time, any water which has separated out is drawn off, and the 
solution is filtered through a filter paper previously dried at 105°. 
After washing with benzene and drying at 105°, the filter paper and 
impurities are weighed. 

Any suspended particles of pitch and asphaltic substances are not 
determined by this method, as they are dissolved by benzene; the 
determination of these is described on p. 9. Any mineral salts 
introduced by the bore-holes mud, or by chemicals added in the 
refining process, are determined by washing the residue on the filter 
with water, evaporating the solution, and weighing the residue. 

Russian specifications direct to dilute a weighed quantity of the oil 
with petroleum spirit and to filter through a filter paper. The residue 
is incinerated and weighed. 

V. YIELD OF NAPHTHA, BURNING OIL, LUBRICATING OIL, ETC. 

Laboratory methods should be adapted to the requirements of the 
works concerned, the nature of the raw materials, the methods of 
distillation in use, and so forth. I'rom one and the same crude oil very 

1 Petroleum, 1906, 2, 285 ; r/. also Rosenthal, Chem. Zeit., 1909, 33, 1259. 

2 Neltel, C/ierrt. ZeU., 1904. 28, 867. ' Graefe, Petroleum, 1906, I, 815, 



YIELD OF NAPHTHA 



b^ 



3^ 




different yields of the various fractions are obtained, depending on the 
method of distillation, the height of the fractionating column, and other 
factors. The general procedure in the laboratory consists in distilling 
from I to I kg. of crude oil in glass or metal retorts. The distillate is 
condensed at first with water and then atmospherically, and is measured 
in definite ranges of boiling points up to 150° (c/. p. 17). The heavy 
fractions boiling above 3CXD° are best dis- 
tilled with superheated steam, in a vacuum 
of 300-400 mm. The characters of the 
distilled fractions are determined after 
purification by shaking with 1-8 per cent. 
of concentrated sulphuric acid.^ 

When mineral oils, after refining with 
acid, are washed with alkali and with 
water, persistent emulsions frequently 
make their appearance. Heavy oils must 
be kept hot and shaken violently to effect 
separation. As this is not easily done 
in a separating funnel, the. washing and 
separating apparatus shown in Fig. i is 
recommended. The glass vessel a, having 
two stopcocks d and d' for emptying, is 
fitted with a glass or aluminium steam- 
coil d, and a glass tube c through which 
air is blown. The lower stopcock d' is 
useful for separating small quantities of 
oil which may have passed through d. 
Should the apparatus be used for refining 
with acid, a third tap may be placed at the shoulder of the vessel, in 
order to separate the oil from resinous matter. The top of the vessel 
may be closed by a suitably bored lid to prevent splashing. Finally, 
the washed oil is dried by blowing the heated oil with air. 

Since the various forms of laboratory distillation apparatus give 
quite discordant results with one and the same crude oil, specially 
constructed apparatus is employed for the fractional distillation of 
naphtha, kerosene, etc., for purposes of commercial control, and in 
Germany especially for Customs purposes.^ These are made of specific 
dimensions, and give reliable comparative results under the same 
conditions of experiment. 

Oils which contain water are carefully dehydrated before testing by 
shaking with calcium chloride at the ordinary temperature. 

In place of the intermittent distillation by Engler's method,^ which 

1 Cf. Holde, MineralSle, p. l6 ^/ seq. "- Cf. Singer, Chem. Rev., 1896, p. 93. 

* Cf. Boverton Redwood, Petroleum and iis Products, vol. ii., p. 204. 



LJ 

Fio. 1 



a' 



8 



MINERAL OILS 



X — 



S3 A 






U-fi,f^->'' 



occupies a considerable time and does not always give concordant 

results, the improved continuous distillation method of Holde and 

Ubbelohde is to be recommended. The apparatus employed (Figs. 

2, 3, 4) consists of the original Engler's flask (Fig. 2), which is heated 

in a sheet-iron oven by a Bunsen burner fitted 
with a tap. The condenser is 60 cm. long. The 
distillate is collected in six test tubes divided 
in 0-2 c.c. and rotatable in a stand. They are 
cooled in water at the ordinary temperature. 

To carry out the test, 100 c.c. of oil are 
filled into the distillation flask. This quantity 
holds good, however, only for petroleum and 
crude oils which yield a sufficient quantity of 
low-boiling constituents in a given time, so 
that the expansion of the heavy oils does not 
p,Q^ 2, cause any difficulty. For high-boiling oils, e.^., 

"astatki" and lubricating oils which would 

readily boil over in a 100 c.c. flask, the flask must have a capacity of 

at least 140 c.c, or the quantity of oil must be reduced to 80 or 90 c.c. 

The temperature at which the first drops of distillate 

fall into the receiver is taken as the boiling point. 
The rate of boiling is fixed at 2 drops a second ; 

this is best controlled by means of a seconds' 

pendulum. 

In some factories, such as those working Gali- 

cian oil, the boiling point limits of the petroleum 

fraction are i50°-275°. All fractions except the last 

are collected and measured without waiting for the 

several fractions to drain off. 

The fractional distillation test prescribed by the 

New York Produce Exchange may be carried out 

with a small still and condenser, or with any other 

simple form of distilling apparatus. The fractions 

taken off the condenser must each form one-tenth 

of the crude oil by volume ; the specific gravities of 

each fraction must then be determined. 

In Germany special apparatus is prescribed for 

the use of Custom officers. The directions are laid 

down in an official publication entitled, Anleitung 

fiir die Zollabfertigiuig, Berlin, 1906, part iii. 




FiQ. 3. 



VI. FLASHING POINT. 



The flashing point of an oil is the temperature at which it gives off 
so much vapour, in the "open test," that the latter takes fire when a 



FLASHING POINT 



flame is passed over the surface of the oil ; or in the " close test," that 
temperature at which so much vapour collects above the surface of the 
oil in a closed vessel (Abel's, Gray's, or Pensky's apparatus) that it 
forms an inflammable mixture with the air contained in the vessel. 

Crude oils from different sources have different flashing points, 
mostly in the neighbourhood of 0°. Those containing much naphtha, 
such as Javanese and American petroleum, have a considerably lower 
flashing point, whilst oils free from naphtha, such as the heavy 
Hanoverian oils, flash between yo" and 80°. 




Fio. 4. 



The flashing point is determined in this country by means of the 
standard Abel apparatus (see p. 29) in the case of low-flash oils, and 
by means of either the Pensky-Martens or Gray's apparatus in the 
case of high-flash oils. In Germany the Abel-Pensky and the Pensky- 
Martens apparatus are used for low-flash and high-flash oils respectively. 
At the recent International Petroleum Congress (Vienna, 1912), the 
Abel-Pensky (Abel-P.) apparatus was adopted as an international 
standard, provided, of course, it be sanctioned by legislation in the 
respective countries.^ 

VII. DETERMINATION OF ASPHALT. 

Some crude petroleums (especially those of Hanover) contain 
notable amounts of asphalt. Analytical methods for its detection and 

^ Cf. Petroleum, 1912, 7, 468. 



10 MINERAL OILS 

quantitative estimation have been proposed by Holde. These methods, 
however, yield only comparative results, and therefore can be only 
looked upon as provisional, especially so as much depends on the 
character of the petroleum spirit employed for the extraction. In 
Germany a special " normal benzine " of the sp. gr. 0-695-0/05 at 
15° and boiling from 65'-95° has been proposed for this purpose. 
{C/.P.21.) 

Detection of Asphalt. — About i c.c. of crude oil is shaken in a test 
tube with 40 c.c. of petroleum spirit, and the liquid allowed to stand. 
If asphalt be present dark flocks separate out either immediately or on 
standing (for a day if necessary). 

Or, 0-5 c.c. of oil is dissolved in 5 c.c. of ether, and 7 c.c. of alcohol 
are added. Hard and soft asphaltic substances are thereb)- precipitated 
as a viscous mass adhering to the sides of the vessel. 

Determination of Asphalt. 

1. Hard Asphalt. — 5 g. of crude oil are shaken in an Erlenmeyer flask 
with 220 c.c. of petroleum spirit ; in the case of oils poor in asphalt, 5-20 
c.c. of oil are taken. After standing for at least a day, the clear liquid 
is decanted through a small pleated filter. The bulk of the precipitate 
is brought on the filter, and the flask and filter are washed with the 
solvent until the filtrate no longer leaves an oily residue on evaporation. 
The asphalt on the filter is then dissolved by means of hot benzene, the 
solution concentrated by distillation, the remainder washed into a 
weighed dish, and the solid residue, after evaporation and drying at 
100°, weighed. This procedure leaves any non-asphaltic matter which 
may have been precipitated by petroleum spirit on the filter; this 
may be estimated separately. 

When it is desired to differentiate between dissolved and suspended 
asphalts in the crude oil, two determinations are made, as above — 
one on the original oil, the other on the same oil after it has been 
filtered without warming. The difference found represents suspended 
asphalt, 

2. Soft Asphalt. — 5 g. of crude oil are dissolved at is"" in 25 vols, 
of ether, and \2\ vols, of 96 per cent, alcohol are added, drop by 
drop, from a burette, with continuous shaking. After standing for five 
hours at 15 , the liquid is filtered as above, and tiie precipitate washed 
with ether-alcohol (2:1), so long as oily matter is extracted ; it is then 
dissolved in benzene and evaporated down. In order to remove any 
paraffin wax in the residue, it is boiled out repeatedly with 30 c.c. of 
96 per cent, alcohol, until no more paraffin wax separates out on 
cooling. Finally, the residue is dried for a quarter of an hour at 105°, 
and weighed. 



PARAFFIN WAX 



11 



VIII. PARAFFIN WAX. 



I. A method of determining paraffin, originally proposed by 
Grotowsky, worked out by Engler and Bohm, and modified by Holde, 
is carried out as follows : — lOO g. of crude petroleum are rapidly distilled 
from a glass retort until a thermometer placed in the vapours registers 
300°. The condenser is then removed, a fresh receiver of known weight 
is fitted, and the remainder of the oil is distilled without a thermometer, 
until only coke is left behind. The weight of the heavy distillate, which 
is considered to contain all the paraffin wax, is then ascertained. 

Of the heavy distillate 5-10 g. are dissolved at the ordinary 
temperature in a mixture of equal volumes of 
absolute alcohol and ether. The solution is placed 
in a test tube (see Fig. 5) cooled to —20" until 
a clear solution results, and so much of the ether- 
alcohol mixture is added until, at —20'^, all oily 
matter has disappeared, and only flocks of paraffin 
are observed. The paraffin wax is then filtered 
off by suction, in a funnel cooled by a freezing 
mixture (see Fig. 5), washed with previously cooled 
ether-alcohol, and finally washed off the filter 
with hot petroleum spirit or benzene into a 
weighed glass dish. After removal of the solvent 
by cautious evaporation on the water-bath, the 
outside of the dish is wiped dry, and its contents 
are examined. If the paraffin is hard, the dish is 
heated for a quarter of an hour at 105", allowed to 
cool in a desiccator, and weighed. Should the 
paraffin, however, be soft, i.e., melting below 45°, 
it is better to dry it for several hours at 50° in a vacuum desiccator. 

In washing the precipitated paraffin with cooled ether-alcohol, 5 c.c. 
of the filtrate must be tested from time to time by evaporation ; wash- 
ing is complete when either the residue is negligible in amount or is 
solid at the ordinary temperature. 

When the method is applied to crude paraffin waxes, 0-5-1 g. is 
weighed out and dissolved in 10-20 c.c. of ether-alcohol (see p. 46). 

A correction is made for the solubility of paraffin wax in ether- 
alcohol. The percentage found is increased by 0-2 per cent, in the 
case of fluid oils, 0-4 per cent, in the case of oils beginning to solidify at 
15°, and I per cent, in the case of crude paraffin wax. 

This method gives the true proportion of paraffin only in the 
case of hard paraffin waxes suitable for candle-making. Soft paraffin 
waxes melting below 50" are not completely precipitated by ether- 




Fio. 



12 MINERAL OILS 

alcohol at —20 ; but the greater part of the paraffin which goes into 
solution can be recovered by evaporating down the filtrate, and redis- 
solving the residue in the least possible quantity of ether-alcohol (i : 2) 
at— 20. In the preliminary distillation (which is only necessary 
with the dark kinds of crude oil), a small proportion of paraffin wax 
undergoes decomposition. This source of error is the more serious, the 
higher the paraffin content of the crude oil ; when there is 5 per cent, 
of paraffin present, the error may amount to 0-5 per cent, on the content 
of paraffin. 

As the method described is universally applicable, other methods 
which have only a restricted application, need only be briefly 
mentioned. 

2. R. Pawlewski and J. Filemonowicz ^ shake from 5-20 c.c. of oil 
with 100-200 c.c. of glacial acetic acid, filter off the separated paraffin, and 
wash it two or three times with glacial acetic acid and then two or 
three times with 75 per cent, alcohol, dry the precipitate, and weigh. 
The method does not, however, give reliable results for the paraffin 
wax in lignite or petroleum, as soft paraffin wax is soluble in glacial 
acetic acid, and heavy mineral oils cannot be separated quantitatively 
from paraffin wax by glacial acetic acid. 

3. R. Zaloziecki - dissolves 10-20 c.c. of the sample in five times its 
volume of amyl alcohol, and precipitates with the same quantity of 75 
per cent, ethyl alcohol at a temperature not exceeding 4". After stand- 
ing for several hours in the cold, the liquid is filtered through a cooled 
filter, and washed with a cooled mixture of 2 parts of amyl alcohol and 
I part of 70 per cent, alcohol. The paraffin wax is then dissolved in ether, 
and after evaporating this off, it is dried at 125^' until the amyl alcohol 
is completely removed. This procedure may be used to determine 
paraffin wax in the presence of fatty acids, neutral fats, rosin and rosin 
oils, but cannot be used in the presence of beeswax, as this is also 
precipitated from amyl alcoholic solution by ethyl alcohol. Shukoff and 
Pantuchoff-' subsequently suggested, as improvements on Zaloziecki's 
method, the use of 90 per cent, ethyl alcohol for the precipitation, and 
the cooling of all the solutions to 0°. The process is not suitable for 
mineral lubricants, especially those which are very viscous, as it is 
hardly possible to separate the paraffin wax completely from the oil. 
If, however, the precautions mentioned are carefully observed, it can be 
used with success for lignite-tar products. The drying of the paraffin 
wax at lower temperatures than 125° is recommended. 

4. R. Holand's method * for the determination of paraffin wax in 

» Ber., 1888, 21, 2973. 

■- Dingl.polyt.J., 1888, 267, 274 ; /. Soc. Chem. Ind., 1888,7, 349- 

^ Russian '■'■Journal of Fats y 1900. 

^ Chem. Zeil., 1893, I?. 1473. ^'nd 1483 ; /. Soc. Chem, InJ., 1894, 13, 286. 



SPECIFIC HEAT la 

lignite-tar products has not been tested for other materials, and is 
probably unsuitable for petroleum products. It depends on the fact 
that the lignite-tar oils containing paraffin are soluble in absolute 
alcohol, and that at a certain temperature only the paraffin separates 
out. 

IX. SPECIFIC HEAT. 

The specific heat of crude oils is of importance, if it be a question 
of using the waste heat of steam for pre-heating the oil previous to 
distillation ; or if dehydration of a crude oil by means of indirect steam 
is contemplated, when the amount of heating surface required can be 
calculated. The specific heat is also required for calculating the 
capacity of the refrigerating plant needed for the recovery of the 
paraffin wax. 

Two methods are in use for the determination of the specific heat. 
E. Graefe^ burns 0-4 1-0-43 S- of a substance of known heat of 
combustion {e.g. pure cellulose, in the form of absorbent pads manu- 
factured by Schleicher and Schiill ; 1 kg. =4175 Cal.) in a bomb 
calorimeter. The sample of oil is used as the outer liquid in the calori- 
meter. From the quantity of cellulose taken («), the quantity of oil {b), 
the water equivalent of the calorimeter (W), and the observed rise of 
temperature (T), the specific heat can be calculated from the formula : — 

«.4i75 = W T 4- ^^T. 

By this method Graefe found the specific heat of various oils to 
range from 0-4-0-5. 

Another method ^ depends upon the measurement of the heat 
produced by passing a current of known intensity (/) for a given time 
(2) through a strip of nickelin of resistance r immersed in the oil under 
examination. The rise of temperature {t) is read off, and the specific 
heat calculated from Joule's law {w being the water equivalent of the 
calorimeter), according to the formula : — 

{ni . c-\-iu) t = 0-239 z'2 r z. 

The results obtained by this method in the " Reichsanstalt " are in 
good agreement with those of Graefe. 

The more hydrogen an oil contains, the higher is its specific heat, 
and the richer it is in carbon and oxygen, the lower its specific heat. 
The specific heat as calculated from the elementary composition by 
Kopp's law, according to which the molecular heat equals the sum of 
the atomic heats, is in very good agreement with the experimental 
value. It is not even necessary to know the molecular composition 

^ Petroleum.^ 1907, 2, 521. 

^ Cf, Kohlrausch, Introduction to Physical Measurements^ translated by Waller and Procter, 
3rd ed., p. 118. 



u 



MINERAL OILS 



of the oil, as it is sufficient to divide the percentages of C, H, and O 
by the respective atomic weii^hts, and to multiply these quotients by 
the atomic heats, viz., C= i-8, H = 2-3, = 40. 

X. LATENT HEAT OF EVAPORATION OF PETROLEUM FRACTIONS. 

A knowledge of these constants is necessary, in designing a works 
plant, for determining the requisite heating arrangements, the dimen- 
sions of the condensers, and the supply of condensing water. It is true 
that these data are commonly arrived at by empirical methods, but 
occasions arise when first principles have to be resorted to. The latent 
heats as required for the proper calculation of distilling and condensing 
plant may be conveniently determined in the apparatus designed by 
V. Syniewski,^ shown in Fig. 6. 




Fio. 6. 



The vapour generated in the flask A, charged with about 400 c.c. 
of the fraction to be examined, passes through a b to the jacketed 
vessel f, and thence past the bell-valve z into the condensing worm c 
fitted inside the calorimeter B. The calorimeter system is closed off 
by z as long as condensation of vapour takes place in l\ whence 
condensed liquid runs off through d. When c contains only vapour, 
free from liquid, ;: is opened and the vapour is admitted into the 
calorimeter, which is charged with about 1200 c.c. of water. The 
thermometers T and / serve to show the temperatures of the calori- 
meter and of the vapour respectively. Distillation into the calorimeter 
is continued until the boiling point has risen by 20^, it being convenient 
to deal with fractions at intervals of 20^ boiling point. The calorimeter 
is now closed off at .:; and the whole of the distilling apparatus 

1 Z. angeu'. Chein., 1898, II, 621 \J. Soc. Chem. fnJ., 189S, 17, 751. 



LATENT HEAT OF EVAPORATION 



15 



removed, when the amount of condensed liquid is determined by 
weighing. The determination of the specific heat is conveniently 
carried out with the condensed liquid. The total heats of evaporation 
determined in this way at the " Reichsanstalt " ranged from 130-190 Cal. 
in the case of various crude oils and the products derived therefrom. 

E. Graefe determines the heat of evaporation by passing the 
vapour of the mineral oil through a form of Liebig's condenser and 
measuring the rate of flow and rise of temperature of the condenser 
water, on the principle of the observations made with the Junkers' 
calorimeter. The loss of heat by radiation is determined in a 
preliminary experiment by distillation of a liquid of known heat of 
evaporation. The heats of evaporation of various lignite-tar oils were 
found to range from 120-220 Cal. 

Graefe^ has also shown that the heat of evaporation can be 
calculated from the molecular weight and the boiling points. Trouton 
had established for definite chemical compounds that when equimole- 
cular quantities are taken, the quotient of the heat of evaporation 
and the absolute temperature of the boiling point is a constant, 
approximately 20. Now although the mineral oils are not definite 
chemical compounds, and moreover have not a constant boiling point, 
Trouton's formula can still be applied to them if mean values are 
adopted for the molecular weight and boiling point. The heat of 
evaporation is then : — 

20 T 



VV 



M 



The mean molecular weight of an oil is determined by the lowering 
of the freezing point of commercial stearic acid. The molecular 
depression is ascertained in a preliminary experiment with a substance 
of known molecular weight ; a weighed quantity {0) of the oil is then 
dissolved in a known quantity {s) of the stearic acid and the depression 
of the freezing point determined. \( k be the molecular depression of 
the stearic acid and t the depression of the freezing point, 

c.ioo. k 



M = 



s t 



The following mean molecular weights were obtained in this way. 

Table 3. 



Lignite-tar oil. 



Light crude oil 
Heavy crude oil 
Gas oil 
Light paraffin oil 



Sp. gr. 



0-883 
0-905 
0-890 
0-920 



Mol. \vt. 



113 

158 
158 
190 



Petroleum^ 1910, 5, 569. 



16 MINERAL OILS 

Charitschkoff,' by calculating the molecular weights from determina- 
tions of the vapour density by Hofmann's method, arrived at results 
similar to those of Graefe. 

For the determination of the mean boiling point the oil is distilled 
continuously in Englcr's apparatus, and the boiling points noted for each 
lo per cent. The arithmetical mean of these temperatures gives the 
mean boiling point. Graefe found the following figures for a light 
crude oil. The liquid commenced to boil at 124°. 

Distillate . 10 p. c. 20 p. c. 30 p. c. 40 p. c. 50 p. c. 



Temperature . 173 184 192 201 



no 



Distillate . 60 p. c. 70 p. c. 80 p. c. 90 p. c. 98 p. c. 

Temperature . 221 234 255 285 



;oo 



From this follows the mean boiling point = 2 16° C. = 489° abs. 
Using Trouton's formula, the heat of evaporation is : — 

W = ^ = --^^^^ = 86.5. 
M 113 ^ 

In order to calculate the total heat of evaporation, the heat necessary 
to raise the oil from the ordinary temperature (25°) to the mean boiling 
point (216°) must be included. Taking the specific heat of the oil as 
0-43, this gives 0-43 (216 — 25) = 82 Cal. Hence, the total heat of 
evaporation is 86-5+82= 168-5 Cal. It is thus seen that in the case of 
this oil, almost as much heat is used in heating the oil to its boiling 
point as in the actual distillation. In many cases the conditions are 
still less favourable. From this result the great importance of warming 
the oil by waste heat before distilling is apparent. 

> ^.—NAPHTHA. 

The term " Naphtha," or " mineral naphtha," or " petroleum naphtha," 
is generally held to cover all those fractions of crude petroleum which 
boil bjslow 150°. The limit of 150^ is not observed by all refineries, 
and the naphthas sold are apt to show wide variations. The nature 
and value of both crude and redistilled naphtha arc determined in the 
laboratory by fractional distillation with a dephlcgmating apparatus. 

In the commercial valuation of naphthas great stress is laid on a 
mild smell and on water-white colour. Patents have recently been 
taken out for masking the evil smell of badly refined naphtha by the 
admixture of turpentine and treatment with alkali. Such additions are 
detected by the methods given on p. 21. 

^ Physikahsche Unkrsuchuug des Erdoh, 



NAPHTHA 



17 



I. SPECIFIC GRAVITY. 

This is measured either by Mohr's balance, hydrometers, or pykno- 
meters, and is stated for a temperature of 15" (see "Lubricants," p. 61). 
The specific gravity test serves chiefly for the identification of a 
sample. 

The subjoined Table, due to Mendelejeff, facilitates the calculation of 
the specific gravity at the working temperature to that at the standard 
temperature of 15°: — 

Table 4. 



Sp. gr. 


Correction for 1°. 


Russian oil. 


Pennsylvanian oil. 


0-700 to 0-720 
0-720 „ 0-740 
0-740 „ 0-760 
0-760 „ 0-780 
0-780 „ 0-800 


0-00082 
0-00081 
0-00080 
0-00079 
0-00078 


0-00086 
0-00082 
0-00077 
0-00072 
0-00068 



II. EVAPORATION TEST. 



Petroleum spirit boiling below ioo° (sp. gr. o-yo-o-yi) should leave 
no residue when evaporated in a watch-glass on a lukewarm water-bath, 
nor should it leave a grease-spot on paper. A negative result with 
both of these tests indicates the certain absence of heavy oils. 



III. FRACTIONAL DISTILLATION. 

Petroleum spirit used as motor fuel should, according to Continental 
practice, contain nothing, or at very most 5 per cent., boiling above 100°. 
If this limit is exceeded, evaporation in the carburettor may become so 
sluggish, especially in cold weather, as to lead to misfires. Hence 
motor petrols, no less than solvent naphthas, need to be tested by 
fractionation. The commercial motor oils, sold in this country under 
the technical term " petrol," have higher boiling points ; as a rule, 
60-70 per cent, only boil below 100°, about 25 per cent, pass over 
between ioo°-i20°, 5-6 percent, from 120°- 13 3'', and about 3 per cent, 
above 133".^ Petrols containing much larger proportions of higher 
boiling fractions are, however, now used in modern carburettors in 
which the exhaust gases jacket the in-going air. 

In the usual commercial distillation test 100 c.c. of naphtha are dis- 
tilled directly from an Engler distilling flask, in the manner described 

^ Cf. B. Blount, " The Composition of Commercial Petrols," The Incorporated Institution of 
Automobile Engineers, loth March, 1909 ; J. Soc. Chem, Ind,, 1909, 28, 419. 

Ill £ 



18 



MINERAL OILS 



on p. 6 for crude oil, and the fractions are collected for each interval 
of lo"). The point at which the first drop of distillate falls from the 
condenser is taken as the commencement of boiling, and the moment 
at which the bottom of the distillation flask is just dry is taken as the 
end point. 

If the barometric pressure is not normal, this must be taken into 
account in stating the boiling points and quantities of liquid in the suc- 
cessive fractions.^ The receiver is changed, in such a case, not exactly 
at each round lo", but at a slightly higher or lower temperature based 
on the deviation of the boiling point of water from the normal at the 
prevailing barometric pressure. R. Kissling has shown that this 
correction is sufficiently accurate for all technical purposes. Such a 
correction is to be applied whenever the atmospheric pressure deviates 
by more than 5 mm. from 760 mm. To correct automatically for 
differences of pressure, Fuss has suggested the use of a thermometer 
with an adjustable scale, the 100" point being adjusted according to the 
boiling point of water under the given barometric pressure; the ther- 
mometer is divided into ^ degrees, so that ^V degrees can be estimated. 



IV. FLASHING POINT. 



As the vapour of petroleum naphtha (boiling as described above) 
ignites well below o^, the determination of the flashing point in the 

Abel apparatus requires special precau- 
tions, and should aim at keeping the 
temperature well below freezing point. 
The container of the Abel apparatus 
(Fig. 7) is therefore placed in a cylindrical 
metal pot /;, about 60 mm. high and 90 mm. 
wide, filled with alcohol. The pot is placed 
in a larger vessel r, about 'jo mm. high 
and 160 mm. wide, also filled with alcohol, 
and well insulated by felt. The cooling 
below o" is effected by introducing solid 
carbonic acid into the alcohol as required. 
The ignition mechanism should be inserted, not from the beginning, 
but immediately before the actual test commences ; otherwise the flame 
may go out during the test, owing to clogging of the wick by cold. 
Moreover, the spring which governs the insertion of the ignition flame 
is apt to work badly at low temperatures, and must be helped by 
frequently turning the knob on the lid of the igniter. A temperature 




Fio. 7. 



* Cf. Ubbelohde, Z. angnv. Chtm., 1906, 19, 1 155 ; and R. Kissling, Client. Zeit., 1908,32, 



695. 



RISK OF EXPLOSION 



19 



of —50° to —60° having been reached, the container a is taken out 
bodily, and wrapped carefully in a cloth ; the test is then carried out 
in the usual manner. After the flash test has been made, the ignition 
point may be determined ; for this purpose the lid is taken off. 

The following flashing points and ignition points of some naphtha 
fractions are given by Holde ^ : — 

B.P. 50'-60^ (30'-7S° 

Flashing point below -58° -39° 
Ignition point ... ~34° 



70°.88° 


SOMOO- 


SOMIS- 


100°-150 


-45" 


-22° 


-22° 


+ 10° 


-42° 


... 


-19° 


+ 16'' 



V. RISK OF EXPLOSION. 

In gas engines, explosive mixtures of gas and air are purposely 
generated. It is to be borne in mind that combustible gases become 
explosive only when they are mixed with air, oxygen, or other gases 
which exercise an oxidising action. However, not every mixture of a 
combustible and an oxidising gas yields an explosive mixture, proper 
proportions of the two being required. Hence, there is a limited range 
of composition, within which explosion can occur. H. Bunte ^ has 
determined the explosive limits for various mixtures of air and gas 
(Table 5) in a gas-burette of 19 mm. diameter, the gas being ignited 
by a powerful electric spark. 

Table 5. 



Gas. 


Percentage of combustible gas in tlie mixture. 










No explosion. 


Limits of explosion. 


No explosion. 


1. Carbon monoxide . 


16-4 


16-6 to 74-8 


75-1 


2. Water gas 


12-3 


12-5 „ 66-6 


G6-9 


3. Hydrogen 




9-4 


9-5 „ 66-3 


66-5 


4. Acetylene 




3-2 


3-5 ,. 55-2 


52-4 


5. Coal gas 




7-8 


8-0 „ 19-0 


19-2 


6. Ethylene 




4-0 


4-2 „ 14-5 


14-7 


7. Alcohol 




3-9 


4-0 „ 13-6 


13-7 


8. Methane 




6-0 


6-2 „ 12-7 


12-9 


9. F.ther . 




2-6 


2-9 „ 7-5 


7-9 


10. Benzene 




2-6 


2-7 „ t)-3 


6-7 


11. Pentane 




2-3 


2-5 „ 4-8 


5-0 


12. Petroleum spirit . 


2-3 


2-5 „ 4-8 


5-0 



These experiments were carried out under strictly comparable 
conditions, as the range of the limits of explosion depends not only on 
the nature of the gas, but also on the diameter of the tube, the method 
of ignition, the pressure, and the temperature. The influence of the 
last factor was determined in the case of carbon monoxide. Whereas 



' Mill. k. MaUrialpriif., 1899, p. 70. - J. Gasbekucht, 1901, 44, 835. 



20 



MINERAL OILS 



the lower limit for this gas at the ordinary temperature is i6-6 per cent., 
it sinks to 14-2 per cent, at 400"", and to 7-4 per cent, at 600". 

It is seen from the Table that the limits of explosion for petroleum 
spirit lie very close together, the upper limit being onl)' 5 per cent, 
of the vapour. On the other hand, it must not be overlooked that 
very small quantities of petroleum spirit are sufficient to cause an 
explosion. 

It is advantageous, instead of employing Bunte's method of deter- 
mination, to allow a certain quantity of vapour of petroleum spirit to 
evaporate into a gasometer holding a known volume of air, and then to 
draw the mixture into a Hempel explosion pipette over mercury for 
the ignition. 



VI. HEAT OF COMBUSTION OF NAPHTHA (PETROL). 

Since benzine has come into use for motors, especially for auto- 
mobiles {cf. also p. 45), the determination of its heat of combustion has 
become of importance, as the value of an oil depends upon its calori- 
metric effect. The determination is carried out in a calorimetric bomb 
(Berthclot's, Mahler's, Krocker's) placed in a water calorimeter, with a 
known quantity of oil and compressed pure oxygen, the ignition being 
effected electrically. The heat evolved by the combustion is measured 
by the rise in temperature of the calorimeter. The apparatu-s and 
the method of determination are described in the section on " Fuel," 
Vol. I., pp. 254 ct seq. 

The heats of combustion of benzine and burning oils are given in 
Table 6 in comparison with those of some other fuels. 

Table 6. 



Heating material. 


Heat of combustion. 


Naphtha 

Petroleum ..... 

Benzene 

Motor Alcohol .... 

Anthracite 

Coal 

Lignite (air-dry) 


11,160 to 11,225 

11,000 „ 11,100 

10,038 

5,940 

8,000 

7,000 to 7,500 

4,500 „ 5,000 



VII. AROMATIC HYDROCARBONS. 



I. Qualitative Dctectio?t. — Asphalt, free from mineral matter, is finely 
powdered and thoroughly extracted with petroleum spirit of sp. gr. 



NAPHTHA 21 

0-70-07 1. A pinch of this is placed in a small filter, and the naphtha under 
examination is poured on to it. The filtrate is collected in a test tube ; 
if it be colourless, benzene is absent, whereas if it show a yellow or 
brown tinge, the presence of benzene or toluene is indicated. This test, 
which is based on the solubility of asphalt in benzene, is sensitive 
enough to indicate an admixture of from 5-10 per cent, of aromatic 
hydrocarbons. 

2. Quantitative Determination. — The method proposed by G. Kramer 
and W. Bottcher,^ and based on the absorption of aromatic and olefinic 
hydrocarbons by sulphuric acid of sp. gr. 1-84 at 15° (prepared by 
mixing 20 vols, of fuming with 80 of ordinary concentrated acid), gives 
only approximately correct results. 

VIII. OIL OF TURPENTINE (AMERICAN, RUSSIAN). 

Oil of turpentine is best detected by determining the boiling point 
the specific gravity, and the iodine value of the sample, or if need be of 
the fractions. American oil of turpentine yields 90 per cent, of distillate 
boiling from i55°-i65°, has the sp. gr. 0-865 at i5°-5, and an iodine 
value of about 400. 

Russian oil of turpentine ("Kienoel") yields 90 per cent, of distillate 
boiling from i6o°-i85°, has the sp. gr. 0-8610, and an iodine value of 
about 320. Benzine, on the other hand, has a much lower specific 
gravity and a very low iodine value - (if any). 

IX. DEGREE OF PURIFICATION. 

Commercial naphtha is more or less deep yellowish. Refined 
naphtha should be absolutely water-white, should impart no colour to 
concentrated sulphuric acid on shaking with it, and should yield no 
acid or other impurities to boiling distilled water. 

X. SOLUBILITY IN ABSOLUTE ALCOHOL. 

The naphtha fractions are completely soluble in absolute alcohol ; 
naphtha is not miscible with 90 per cent, alcohol. 

XI. PETROLEUM SPIRIT (NAPHTHA OR "NORMAL BENZINE"). 

As benzines used for the determination of "asphaltic substances" in 
dark mineral oils yield very different results according to their individual 
boiling points, the German " Verband fiir die Materialpriifungen der 

^ Gewerbejleiss, 1887. 

- Cf. Lewkowitsch, Chem. Technology of Oils, Fats, and Waxes, vol. iii., p. 125. 



22 MINERAL OILS 

Technik" introduced in 1903 a "normal benzine" for these tests. This 
benzine is supplied solely by the firm of C. A. F. Kahlbaum, Berlin, 
under the control of the Royal Materialpriifungsamt at Gross-Lichter- 
felde near Berlin. This normal benzine must answer the following 
requirements : — 

Sp. gr. at 15°, 0-695-0-705 ; extreme limits of boiling point 65^-95° 
(determined by continuous distillation from a small flask with a three- 
bulb Le Bel-Henninger fractionating column). It must not contain 
more than 2 per cent, of substances which dissolve in a mixture of 80 
parts of concentrated and 20 parts of fuming sulphuric acid. 

XII. PETROLEUM SPIRIT FOR VARNISHES AND OIL OF 
TURPENTINE SUBSTITUTES. 

The identification of pure oil of turpentine substitutes, such as 
"Kienol" (see above, p. 21), perchlorethylene, etc., presents no 
analytical difficulties.^ 

The substitutes used in the manufacture of varnishes, sold in this 
country as " White Spirit," have, as a rule, a flashing point above 23° 
(73° F.), mostly at 26''-7 (80° F.), evaporate as nearly as possible at 
the same rate as does genuine oil of turpentine, yield 90 per cent, of 
distillate up to 140", have a sp. gr. of about 0-785, and are characterised 
by a mild odour. 

The rate of evaporation is determined by a comparative tes.t with 
pure oil of turpentine, the liquids being evaporated in a platinum dish 
on a boiling water-bath. Pure oil of turpentine may leave from 1-5-2 
per cent, of a solid residue ; the substitute, however, should leave no 
residue. A convenient comparative test, which can be carried out in 
the cold, is to moisten a strip of filter paper with an equal number 
of drops of turpentine and the benzine under examination, and to 
observe the time which elapses before the liquid has evaporated off 
completely. 

Many quantitative methods have been proposed for the determina- 
tion of benzine in turpentine substitutes,- but these have all been 
rejected on account of inaccuracy. The method which has proved 
itself the best is J. Marcusson's^ modification of Burton's method, in 
which fuming nitric acid is allowed to act on 10 c.c. of the oil at — lo^ 
Turpentine and " Kienole " pass completely into solution under this 
treatment, or give at most 1-5 per cent, of precipitate. A defect in the 
original method was that certain components of the benzines, viz., 

1 Cf. Lewkowitsch, loc. cit. 

2 QC H. E. Armstrong, /. Soc. Chem. Ind., 1882, I, 478 ; Richardson and Bowen, /. Soc. 
Chem. /luL, 1908, 27, 613 ; Burton, Amer. Chem. /., 1890, 12, I02 ; Allen, Chem. Znitr., 1890, 

II., 125. 

'■^ MilUilungen, 1908, p. 157 ; J. Soc. C/um. /mi., 1909, 28. 1096. 



BURNING OIL (KEROSENE) 



23 



aromatic and olefinic hydrocarbons, also pass into solution, giving rise 
to low results in the determination of the benzines. In the subjoined 
Table a series of results obtained by this method for oil of turpentine 
mixed with Galician and Sumatra benzines are given. 







Table 


7- 








Source of benzine used. 


Percentage 
of benzine. 


Insol. 

in 
nitric 
acid. 


Extract from nitric acid 
solution (freed from acid). 


Benzine 
content 
found. 


Difference 

between 

found 

and true. 




Per cent. 


g. 


c.c. 


Per cent. 

on 

original oil. 


Per cent. 


Percentage. 


Sumatra (heavy) 
„ (light) . 


80 
80 


49-0 
57-5 


3-82 
2-40 


3-32 
2-10 


33-2 
21-0 


82-2 
78-5 


+ 2-2 
-1-5 


(heavy) . 
Galicia . 


60 
40 


33-0 
30-0 


2-80 

ro2 


2-44 
0-90 


24-4 
9-0 


57-4 
39-0 


-2-6 
-1-0 




20 


11-0 


1-03 


0-90 


9-0 


20-0 


+ 0-0 


Sumatra (heavy) . 


10 


4-0 


0-79 


0-70 


7-0 


11-0 


+ 1-0 



Marcusson's method also gives valuable information as to the source 
of the benzine present. If the range of boiling point is ioo°-i8o° and 
the specific gravity of the portion insoluble in nitric acid is 072-0-73, 
the benzine is probably of American origin ; a specific gravity of 
o- 74-0-75 indicates Galician or Roumanian benzine ; 0-76-0-77, Indian ; 
0-78, Russian. A second criterion is the content of substances soluble 
in nitric acid. Taking, as before, a boiling point from ioo°-i8o°, the 
percentage of soluble matter calculated on the total benzine is, in the 
case of American and Russian benzines, 8-10 per cent. ; in Galician and 
Roumanian, 15-20 per cent. ; in Indian, 22-40 per cent. 

A modification of Armstrong's polymerisation method for this 
estimation has been recently recommended by R. S. Morrell.^ 

C— BURNING OIL (KEROSENE). 



I. COLOUR. 

Good burning oil (Kerosene, paraffin oil, etc.) boiling between 150° 
and 300° and prepared by treating the crude oil with sulphuric acid, 
should be clear, transparent, and, at most, of a faintly yellow tint. The 
higher grades, such as " water-white," are colourless. On exposure to 
sunlight all burning oils become slightly discoloured, without however 
suffering to any extent in their illuminating properties. For commercial 
purposes burning oil is classified according to colour. Standardising 

1 J. Soc. Chetn, Ind., 1910, 29, 241. 



24: 



MINERAL OILS 



colorimeters, which enable the grade of an oil to be determined, have 
been devised by A. Wilson, and by C. Stammer. 

I. IVt/son's Colorimeter consists of a box, the lid of which may be 
clamped at an)' angle and acts as a stand for two brass tubes b (Figs. 
8 and 9), 16 in. long, holding the oil and the standard glasses 
respectively. Both tubes are closed by thin glass plates fixed in 
screw-caps. A mirror at the bottom of the lid reflects the light through 
the tubes and through a pair of prisms into the eye-piece. The field, as 
seen through the eye-piece, is divided by a sharp line which allows of 
the comparison of the two halves of the field, which are tinted 
respectively with the colour of the oil and that of the standard. A 
series of four standard glasses is supplied with each colorimeter, 
corresponding, in ascending order of depth, to the four commercial 
grades — water-white, superfine white, prime white, and standard 
white. 





Fio. 8. 



Fig. 9. 



In making a determination, one of the tubes is filled with oil, the 
other remaining empty. The tubes are first fixed in position ; one-half 
of the field seen through the eye-piece will now, of course, be darker 
than the other. Standard glasses are then inserted in the empty tube, 
until both halves of the field have approximately the same tint. The 
grade of the oil is thus fixed. 

It is very rare that an oil corresponds exactly to one of the standard 
glasses. Since, however, these are the only recognised standards, if the 
colour of an oil should lie between say No. 2 and No. 3 standard, the 
oil is classified according to the darker tint, i.e. as No. 3. In Baku the 
common practice is to express the grade in fractions of the standard 
number. 

The colour of the burning oil manufactured at Baku generally lies 
between the standard numbers 2 and 3. Intermediate fractions are 
determined as follows : — Standard glass No. 2 is placed over the tube 
containing the oil, and No. 3 over the empty tube. If the two halves 
of the field be found to be equalised, then the grade of the oil is 2\. 



KEROSENE. COLOUR 



25 



If under these conditions the oil appears too dark, the grade 2f is 
assigned to it ; if too h'ght, the grade 2j. Again if glass No. i on the 
filled tube compensates No. 3 on the empty one, the oil is graded as 
No. 21 

2. Stammers Colorimeter. — This instrument has the advantage over 
that of Wilson that it allows of the variation of the length of the column 
of oil measured, whereby the shade 
of colour can be more accurately de- 
fined. It is largely used at Baku. 

The construction of the apparatus 
is shown diagrammatically in Fig. 10. 
A fixed tube ^, on which is placed a 
standard glass plate ti is arranged side 
by side with a cylinder c in which the 
oil is placed ; this cylinder can be 
moved up and down by means of the 
hand-wheel k, whereby the length of 
the column of oil under comparison is 
varied at will. Both z and c are closed 
at the bottom by thin glass plates 
through which the light reflected from 
the mirror p reaches the eye-piece 0. 
The length of the column of oil is 
adjusted until both fields, as seen 
through the eye-piece, have the same 
depth of tint, and this length is 
measured on the scale m. 

The use of the single glass standard 
was found by Boverton Redwood ^ to 
be open to objection, as the sensitive- 
ness of the test was much impaired in 
cases in which the column of oil had 
to be greatly shortened for the com- 
parison. Modifications introduced by R. Redwood have overcome this 
defect. The space between any two of the four commercial shades is 
divided into ten equal parts, so that if the colour, for instance, of a 
sample is midway between " water-white " and " superfine white " it 
would be indicated by the figure 1-5. 

The following Table gives the relations between grade number by 
Wilson's colorimeter, and height of column in Stammer's colorimeter. 
The figures in the third column, in the case of whole grade num.bers, 
were arrived at by direct experiment, and in the case of the remaining 
numbers, by calculation. 

1 Cf. Petroleum and its Products^ 3rd ed., 191 3, vol. ii , p. 215. 




Fig. 10. 



26 



MINERAL OILS 



Standard white 


. No 


4 


?o 


mm. 


Prime white . 


. No. 2l 


172 


>) 


)i 


3^ 


68 


11 


Superfine white 


• » 2 


199 


Prime white 


5) 


3 


86-5 


>) 


)» 


• „ li 


255 


>i 


)) 


24^ 


H5 


>) 


Water-white . 


• ., I 


310 


»» 


»> 


2^ 


143 


)i 









inm. 



According to the rules of the Baku section of the Imperial Russian 
Technical Society, the colour of a burning oil is by no means the only 
factor determining its degree of purity or its behaviour in burning. 
As, however, burning oil is bought and sold very largely on a basis of 
colour, it was regarded as desirable to standarise the colorimetric tests 
employed. Since the tints of the standard glasses in the above-described 
colorimeters are found to vary a little, a minute comparison of grades, 
Wilson numbers, and Stammer columns, was made by the Baku 
section with a readily reproducible standard, viz., potassium chromate 
dissolved in acidulated water in a column 404-6 mm. high. The results 
of these tests are given in the following Table : — 

Table 8. 



Grade. 


Number. 


Percentage 
strength of 


Column of oil 
In mm. 






K2Cr04 solution. 




Water-white . 


1-0 


•000272 


957^9 




1-1 


•000309 


843-2 


11 

91 * * 


1-2 


•000346 


753-1 


f 1 * * 


1-3 


•000384 


680-3 


9) * * 


1-4 


•000421 


618^9 


11 • • 


1-5 


•000458 


568-4 


tv • • 


1-6 


•000495 


526-4 


!• * * 


1-7 


•000532 


489-8 




1-8 


•OOOf.70 


557-1 


11 • • 


1-9 


•000607 


429-3 


Superfine white 


2-0 


•000644 


404-6 


11 * * 


2-1 


•000836 


294-1 


If • * 


2-2 


•001129 


230-8 




2-25 


•001220 


208-5 




2-3 


•001371 


191-1 


11 * • 


2-4 


•001614 


161-4 


>1 ■ • 


2-5 


•001856 


140-4 


11 * * 


2-6 


•002098 


124-2 


11 • • 


2-7 


•002341 


111-3 


11 • • 


2-75 


•002462 


105-8 


11 " • 


2-8 


•002583 


100*9 


11 • • 


2-9 


•002826 


92-2 


Prime white . 


3-0 


•003068 


84-9 


»1 • * 


3-1 


•003325 


78-4 


11 * * 


3-2 


•003581 


72-8 


11 • " 


3-3 


•003838 


67-9 


11 ' • 


3-4 


•004094 


63-6 


11 • * 


3-5 


•004351 


59-9 


1 1 • • 


3-6 


•004608 


56-5 


11 * " 


3-7 


•004864 


53-5 


)1 • • 


3-8 


•005121 


50-9 


n ' • 


3-9 


•005377 


48-5 


Standard white 


4-0 


•005634 


46-2 



It will be observed that the scale of solutions of potassium chromate 
is so designed that each interval between two standard commercial 
grades is divided into tenths. Thus the difference for each unit 



KEROSENE. SPECIFIC GRAVITY 



27 



is -000037 per cent, chromate between water-white and superfine white, 
•0000242 per cent, between superfine white and prime white, and so on. 
The colour of any given oil can be stated in terms of this scale by 
comparing it in a Stammer colorimeter with a standardised glass 
having the tint of a 404-6 mm. column of superfine white oil. Superfine 
white is the most suitable standard, because with it the inevitable 
qualitative differences of colour are reduced to a minimum. An oil 
paler than superfine white must be compared with a water-white glass, 
since columns longer than 404-6 mm. cannot be examined. 

When comparison is made with a glass corresponding to water- 
white, the following Table gives the requisite data : — 

Table 9. 



Grade. 


Number. 


Percentage 
strength of 


Column of oil 






K2Cr04 solution. 




Water-white . 


1-0 


•000272 


404-6 






1-1 


•000309 


356-2 






1-2 


•000346 


318-1 






1-3 


•000384 


286-6 






1-4 


•000421 


261-4 






1^5 


•000458 


240-3 






1^6 


•000495 


222-3 






1-7 


•000532 


206-9 






1^8 


•000570 


193-1 






1^9 


-000607 


181-3 


Superfine white 


2^0 


-000644 


170-9 



Colorimeter glasses which have not quite the correct standard colour 
are themselves standardised by comparison with potassium chromate 
solutions. The amount of divergence having been ascertained, the 
proper correction is applied in the fourth column of the Tables, when 
such a glass is used. 

II. SPECIFIC GRAVITY. 

The specific gravity is, as a rule, expressed for a temperature of 15° 
compared with water at 4". 

The corrections to be applied for temperatures differing from 15° 
are given in the following Table prepared by Mendelejeff : — 

Table 10. 



Range of sp. gr. 


Correction for 1°. 


0-760 to 0-780 
0-780 „ 0-800 
0-800 „ 0-810 
0-810 „ 0-820 
0-820 „ 0-830 
0-830 ,, 0-840 
0-840 „ 0-850 
0-850 „ 0-860 


-000790 
•000780 
•000770 
•000760 
•000750 
•000740 
•000720 
•000710 



28 MINERAL OILS 

Petroleum increases perceptibly in specific gravity on keeping for a 
long time, even in stoppered bottles; Engler^ ascribes this as being 
due to polymerisation. 

in. VISCOSITY. 
This, if required, may be determined by means of Redwood's visco- 
meter, which is fully described in the section on " Lubricating Oils " 
(p. 66). 

IV. SOLIDIFYING POINT. 

Burning oils, if likely to be used in open places, must remain liquid 
below the freezing point of water. The test is carried out as described 
in the section on " Lubricants" (p. 70). 

American petroleum separates particles of paraffin at - 10° unless it 
has been carefully distilled, whereas Russian petroleum remains 
perfectly clear at — 20°. 

V. FLASHING POINT. 

The flashing point of a mineral oil is that temperature at which it 
begins to evolve inflammable vapour in sufficient quantity for a 
momentary " flash" to occur on the application of a flame. The testing 
of the flashing point as a safeguard against the presence of very 
volatile hydrocarbons in burning oils has been made the basis of 
legislation in regard to petroleum. The test is an arbitrary one, and 
various forms of instruments have been adopted in different countries 
for legislative purposes. 

The first Petroleum Act in this country was passed in 1862, but 
remained practically inoperative, as no method of testing was prescribed. 
Subsequent Acts were passed in 1868 and 1871, in which an "open 
test " was prescribed. Petroleum was defined for the purposes of these 
Acts as "any Rock oil, Rangoon oil, Burma oil, oil made from 
petroleum, coal, schist, shale, peat, or other bituminous substance, or 
any products of petroleum, or any of the above-mentioned oils which 
gives off an inflammable vapour at a temperature of less than i(X)° F," 
In 1879 a further Petroleum Act was passed, as the result of investiga- 
tions by Sir Frederick Abel, in which the " closed test," now known as 
the Abel test, was adopted. The result of a large number of experi- 
ments on the difference between the flashing points with the open-cup 
instrument and with Abel's closed tester gave a mean value of 27' F., in 
accordance with which the new standard of temperature was fixed at 
73° F. (22'.8C.). This Act of 1879, in conjunction with that of 1871, 
is still in force. The specification of the test apparatus and the details 
for applying the test are given below. Every apparatus in use for 
official purposes must be standardised by the Board of Trade. 

Ber., 1900, 33, 7. 



KEROSENE. FLASHING POINT 



29 



The Abel Petroleum Test Apparatus. 

Specification of the Test Apparatus. — The following is a descrip- 
tion of the details of the apparatus, Fig. 1 1 : — The oil cup consists of a 
cylindrical vessel 2 in. diameter, 2j% in. height (internal), with outward 
projecting rim yV i"- wide, f in. from the top, and if in. from the 
bottom of the cup. It is made of gun metal or brass (17 B.W.G.) 
tinned inside. A bracket, consisting of a short stout piece of wire bent 
upwards and terminating in a point, is fixed to the inside of the cup to 
serve as a gauge. The distance of the 
point from the bottom of the cup is i^ in. 
The cup is provided with a close-fitting 
overlapping cover made of brass (22 
B.W.G.), which carries the thermometer 
and test lamp. The latter is suspended 
from two supports from the side by means 
of trunnions upon which it may be made 
to oscillate ; it is provided with a spout, 
the mouth of which is tV ^i^- i^"* diameter. 
The socket which is to hold the thermo- 
meter is fixed at such an angle and its 
length is so adjusted that the bulb of the 
thermometer when inserted to its full 
depth shall be li in. below the centre of 
the lid. 

The cover is provided with three square 
holes, one in the centre, j% in. by yV ^"-j 
and two smaller ones, j\ in. by y%- in., 
close to the sides and opposite each other. 
These three holes may be closed and 
uncovered by means of a slide moving in 
grooves, and having perforations corres- 
ponding to those on the lid. 

In moving the slide so as to uncover 
the holes, the oscillating lamp is caught 
by a pin fixed in the slide, and tilted in 
such a way as to bring the end of the spout just below the surface 
of the lid. Upon the slide being pushed back so as to cover the holes, 
the lamp returns to its original position. 

Upon the cover, in front of and in line with the mouth of the lamp, 
is fixed a white bead, the dimensions of which represent the size of the 
test flame to be used. 

The bath or heated vessel consists of two flat-bottomed copper 
cylinders (24 B.W.G.), an inner one of 3 in. diameter and 2| in. height, 




30 MINERAL OILS 

and an outer one of 5^ in. diameter and 5^ in. height ; they are soldered 
to a circular copper plate (20 B.W.G.) perforated in the centre, which 
forms the top of the bath, in such a manner as to enclose the space 
between the two cylinders, but leaving access to the inner cylinder. 
The top of the bath projects both outwards and inwards about '^ in. ; 
that is, its diameter is about 4 in. greater than that of the body of the 
bath, while the diameter of the circular opening in the centre is about 
the same amount less than that of the inner copper cylinder. To the 
inner projection of the top is fastened, by six small screws, a flat ring of 
ebonite, the screws being sunk below the surface of the ebonite, 
to avoid metallic contact between the bath and the oil cup. The 
exact distance between the sides and bottom of the bath and of the oil 
lamp is one-half of an inch. A split socket similar to that on the cover 
of the oil cup, but set at a right angle, allows a thermometer to be 
inserted into the space between the two cylinders. The bath is further 
provided with a funnel, an overflow pipe, and two loop handles. 

The bath rests upon a cast-iron tripod stand, to the ring of which is 
attached a copper cylinder or jacket (24 B.W.G.) flanged at the top, and 
of such dimensions that the bath, while firmly resting on the iron ring, 
just touches with its projecting top the inward-turned flange. The 
diameter of this outer jacket is 6h in. One of the three legs of the 
stand serves as support for the spirit lamp attached to it by means of a 
small swing bracket. The distance of the wick holder from the bottom 
of the bath is i in. 

Two thermometers are provided with the apparatus, the one for 
ascertaining the temperature of the bath, the other for determining the 
flashing point. The thermometer for ascertaining the temperature of 
the water has a long bulb and a space at the top. Its range is from 
about 90''-r9o'F. The scale (in degrees Fahrenheit) is marked on 
an ivory back fastened to the tube in the usual way. It is fitted 
with a metal collar, fitting the socket, and the part of the tube below 
the scale should have a length of about 3^ in. measured from the lower end 
of the scale to the end of the bulb. The thermometer for ascertaining 
the temperature of the oil is fitted with a collar and ivory scale in a 
similar manner to the one described. It has a round bulb, a space at 
the top, and ranges from about 55 -150" F.; it measures from end of 
ivory back to bulb 2\ in. 

Note. — A model apparatus is deposited at the Weights and 
Measures Department of the Board of Trade. 

Directions for applying the Flashing Test. — i. The test apparatus 
is to be placed for use in a position where it is not exposed to 
currents of air or draughts. 

2. The heating vessel or water-bath is filled by pouring water into 
the funnel until it begins to flow out at the spout of the vessel. The 



ABEL FLASHING POINT APPARATUS 31 

temperature of the water at the commencement of the test is to be 
1 30° F., and this is attained in the first instance either by mixing hot 
and cold water in the bath, or in a vessel from which the bath is filled, 
until the thermometer which is provided for testing the temperature of 
the water gives the proper indication ; or by heating the water with the 
spirit lamp (which is attached to the stand of the apparatus) until the 
required temperature is indicated. 

If the water has been heated too highly, it is easily reduced to 
I30°F. by pouring in cold water, little by little (to replace a portion of 
the warm water), until the thermometer gives the proper reading. 

When a test has been completed, this water-bath is again raised to 
I30°F. by placing the lamp underneath, and the result is readily 
obtained while the petroleum cup is being emptied, cooled, and refilled 
with a fresh sample to be tested. The lamp is then turned on its swivel 
from under the apparatus, and the next test is proceeded with. 

3. The test lamp is prepared for use by fitting it with a piece of flat 
plaited candle wick, and filling it with colza or rape oil up to the lower 
edge of the opening of the spout or wick tube. The lamp is trimmed 
so that when lighted it gives a flame of about 0-15 in. diameter, and this 
size of flame, which is represented by the projecting white bead on the 
cover of the oil cup, is readily maintained by simple manipulation from 
time to time with a small wire trimmer. 

When gas is available it may be conveniently used in place of the 
little oil lamp, and for this purpose a test- flame arrangement for use 
with gas may be substituted for the lamp. 

4. The bath having been raised to the proper temperature, the oil 
to be tested is introduced into the petroleum cup, being poured in 
slowly until the level of the liquid just reaches the point of the gauge 
which is fixed in the cup. In warm weather the temperature of the 
room in which the samples to be tested have been kept should be 
observed in the first instance, and if it exceeds 65° F. the samples to 
be tested should be cooled down (to about 60° F.) by immersing the 
bottles containing them in cold water, or by any other convenient 
method. The lid of the cup, with the slide closed, is then put on, and 
the cup is placed into the bath or heating vessel. The thermometer in 
the lid of the cup has been adjusted so as to have its bulb just immersed 
in the liquid, and its position is not under any circumstances to be altered. 
When the cup has been placed in the proper position, the scale of the 
thermometer faces the operator. 

5. The test lamp is then placed in position upon the lid of the cup, 
the lead line or pendulum, which has been fixed in a convenient 
position in front of the operator, is set in motion, and the rise of the 
thermometer in the petroleum cup is watched. When the temperature 
has reached about 66" F. the operation of testing is to be commenced. 



32 



MINERAL OILS 



the test flame being applied once for every rise of one degree, in the 
following manner : — 

The slide is slowly drawn open while the pendulum performs three 
oscillations, and is closed during the fourth oscillation. 

Note. — If it is desired to employ the test apparatus to determine 
the flashing points of oil of very low volatility, the mode of proceeding 
is to be modified as follows : — 

The air chamber which surrounds the cup is filled with cold water 
to a depth of ih in., and the heating vessel or water-bath is filled as 

usual, but also with cold water. The 
lamp is then placed under the ap- 
paratus and kept there during the 
entire operation. If a very heavy 
oil is being dealt with the operation 
may be commenced with water pre- 
viously heated to 120', instead of 
with cold water. 

Effects of Variation in Baro- 
metric Pressure. — The results ob- 
tained with the Abel apparatus vary 
with the barometric pressure, the 
difference in the flashing point 
amounting to o^'-6t,6 F. (0^-30 C.) for 
each 10 mm. difference in pressure. 
A Table of corrections, given on 
p. 37, is in use in Germany in con- 
nection with the Abel-Pensky instru- 
ment ; no corrections are prescribed 
by the Petroleum Act in this 
country. 

Effect of a Tropical Climate- — The effect of a tropical climate on 
the liberation of vapour causes a lowering of the flashing point. In- 
vestigations by F. Abel and Boverton Redwood ^ have shown that this 
source of error in the determination of the flashing point may be 
overcome by commencing the test many degrees below the flashing 
point, so that the vapour is withdrawn by the current of air created by 
the test flame, in successive quantities too small to cause a flash 
before volatilisation of the oil begins. With this modification, which is 
embodied in the Indian Petroleum Act, 1899 (as modified to 1st Nov, 
1903), the results obtained at a tropical temperature agree very closely 
with those obtained in a temperate climate.- The Act prescribes the 
Pensky modification of the Abel apparatus (p. 33) for carrying out the 




Fig. 12. 



test. 



J C/iat/i. A'fws, 1884, 49, 196. 

- C/. Redwood, Petroleum and its Products, vol. ii-, pp. 231-23S. 



ABEL-PENSKY APPARATUS 



33 



Petroleum Mixtures. — Since mixtures of petroleum with other 
substances present similar dangers to petroleum without admixture, 
an Order in Council^ was introduced in 1907 in regard to such 
mixtures. The prescribed apparatus (Fig. 12) differs from the Abel 
apparatus described above in the addition of a stirrer, to equalise 
the temperature throughout the sample during the test, and must be 
used for all viscous and sedimentary mixtures. 

The Abel-Pensky Petroleum Test Apparatus. 
This modification of the Abel apparatus is provided with a clock-- 
work arrangement for the removal of the slide and the application of the 




Fia. 13. 



test-flame, whereby greater uniformity is secured in the tests and the 
liability to the personal error introduced by the method of applying the 

1 Statutory Rules and Orders, 1907, No. 483. Published by Wyman & Sons, Fetter Lane, 
London, E.G. 

Ill c 



34 



MINERAL OILS 



test-flame is considerably reduced. It has been adopted as the 
standard instrument for legislative purposes in Germany, Russia, and 
in India. 

The apparatus (Fig. 13) consists of a water-bath W, an oil-container 
G, a lid fitted with a thermometer, and an igniting device, operated by 
a special mechanism. In the lid of the water-bath are fixed a funnel C, 
an exit-pipe (not shown in the figure), and a thermometer /.,. A hollow 
copper vessel dips into the water-bath. This acts as an air-jacket to the 
container, and has an ebonite-lined neck. The container G, which fits 
into this neck, is tinned internally and provided with a grip //j, up to the 
level of which it is filled with the oil to be tested. The lid of G carries 
a thermometer /j, and on it lies the flat metal slide-valve S, which is 
actuated by the clockwork mechanism T, and is pierced with a series 
of holes corresponding with holes in the lid of G ; at one end of the 
stroke G is thus closed off, and at the other end it communicates with 
the open air through the holes referred to. 

To set the clockwork in action, the screw b is turned to the right as 
far as it will go. On depressing the lever //, the slide-valve is set in 
motion. At the same time the small lamp <?, which oscillates on a 
horizontal swivel, is made to dip downwards; the lamp has a spout d, 
which carries a wick at which a tiny flame is kept burning. Matters 
are so adjusted that this flame dips into the upper part of G (which 
contains a mixture of oil vapours and air) for two seconds at the point 
where the openings of the slide-valve are over the openings of G. ' 

To determine the flashing point the oil is introduced into the 
container by means of a pipette, and is cooled, before the ignition 
mechanism is brought into play, to 2° below the lowest possible 
limit of the flashing point. The initial adjustment of temperature is 
effected before G is placed in the water-bath. Care should be taken 
that no oil lodges on the inside of G above the level of//. 

The relation between the barometric pressure and the temperature 
at which testing should begin is shown by the following Table : — 



Table 11. 



Barometric pressure. 


Initial temperature. 


From 685 to 695 mm. 


+ 14-0°C. 


Above 695 „ 705 „ 


14-5 


,1 705 „ 715 „ 


15-0 


,1 715 „ 7'25 „ 


15-5 


11 725 „ 735 „ 


16-0 


„ 735 „ 745 „ 


16-0 


11 745 „ 755 „ 


16-5 


„ 755 „ 765 „ 


17-0 


„ 765 ,, 775 „ 


17-0 


1, 775 „ 785 „ 


17-5 



ABEL-PENSKY APPARATUS 35 

The ignition flame, which is fed, through a cotton wick, from the 
petroleum reservoir de, is lighted when the temperature of the water-bath 
has reached 54°-55° C. (i29°-i3i° F.), and is set in motion by winding 
up b and depressing li ; at the same time the spirit lamp L is 
extinguished. The test is made at \° intervals. A white bead let 
into the lid of the tester indicates the size to which the flame should 
be adjusted. 

As the flashing point is approached, the ignition flame is observed to 
grow larger through the formation of a halo of light surrounding it. 
The true flashing point, however, is not reached until a momentary blue 
flame plays over the whole empty space above the oil. A further 
condition is that the ignition flame shall not be blown out by this 
occurrence, as often happens in the first flashings. The temperature at 
which definite flashing sets in is read off at the thermometer t^. 

The test is repeated with a fresh portion of the oil, and if the result 
of the second test does not differ by more than o°-5 from the first, the 
mean of the two temperatures is taken as the flashing point; should 
the two readings differ by i° or more, a third test is made, and if the 
maximum difference between the three readings does not exceed i°-5, 
the average is takeif. 

The minimum flashing point prescribed in Germany is 21° C. 
(69''-8 F.) at 760 mm. pressure. The apparent flashing points must be 
corrected for pressure in accordance with Table 12 (p. 37), in which 
flashing points from i5°-S-25°-9 are tabulated under pressures from 
650-785 mm. ; the flashing points at the normal pressure are given in 
the column between the two thick lines, and the corresponding flashing 
points at other pressures are given in the same horizontal line. 

Other Apparatus for testing the Flashing Point of Petroleum. 

Several other forms of apparatus have been devised for testing the 
flashing point of petroleum. 

In the State of New York an apparatus devised by A. H. Elliot is 
prescribed for legal purposes, whilst in many of the other States of the 
American Union the Tagliabue closed tester or cup has been adopted. 
In France, Granier's automatic tester is employed officially. A full 
description of these instruments together with directions for their use 
and the legislative conditions governing the testing, storage, transport, 
and use of petroleum and its products in the respective countries 
is given in the treatise on Petroleum and its Products^ by Sir 
Boverton Redwood, vol. ii., pp. 216-266, and vol. iii., pp. 1-81, 3rd 
ed, 191 3. 

The Pensky-Martens apparatus and that of J. Gray, both of which 
are employed for determining the flashing point of the heavier mineral 
oils, are described in the section on " Lubricants," pp. TJ et seq. 



36 MINERAL OILS 

An important series of experiments with the apparatus used for 
the determination of the flashing points of illuminating oils has been 
carried out by J. A. Ilarker and W. F. Higgins at the National Physical 
Laboratory, for the International Commission on Petroleum Products.^ 

VI. IGNITION OR "FIRE" TEST. 

The temperature at which an oil takes fire on the approach of a flame 
and continues burning is known as the Ignition or "Fire Test." It 
may be determined in Abel's apparatus by using it as an open tester. 
A small flame is brought near to the surface of the oil for a second or 
two after each rise of i° of temperature, or the lid of the container may 
be removed after a flashing point determination and the heating 
continued with periodical applications of the ignition flame. 

When the flashing point of an oil is well above the prescribed 
minimum, the fire test is of little interest and is only determined 
in special cases. 

VII. FRACTIONAL DISTILLATION. 

Valuable information as to the composition and true quality 
of kerosene is afforded by a fractionation test. No fixed standards 
have been generally accepted, but it is usual to collect and note 
the distillates below 150^ from iSo"'-200^ from 20o''-25o'', and from 
25O°-3O0° ; the residue above 300° is estimated by difference. -The 
measurements are usually made by volume, from which the actual 
weights can be ascertained, if required, from the volumes and specific 
gravities. 

The apparatus used for the examination of crude petroleum can be 
employed for the fractionation [cf. p. 6). Other forms of apparatus 
have been described by J. Biel- and by W. Thorner.^ 

VIII. DEGREE OF PURIFICATION. 

I. Sulphur Compounds. — The presence of sulphur compounds in 
kerosene gives rise to a disagreeable smell in the products of combus- 
tion and vitiates the atmosphere. 

They may be estimated by burning a known weight of the oil in a 
suitable lamp and passing the products of combustion through a 
cylinder moistened with ammonia, as in the Gas Referees' Test for 
sulphur in illuminating gas ; the sulphur dioxide formed is then oxidised 
and finally weighed as barium sulphate. This test is fully described in 
the section on "Illuminating Gas and Ammonia," Vol. II., Part II., 
pp. 669 et seq. As the result of an extended investigation Boverton 

1 Petroleum World, 1911, pp. 303, 35 1, 397. - Dingl. polyt. J., 1884, 252, II9. 

3 Chem. Zeii., 1886, 10, 528, 553, 573, 582, and 601 ; /. Soc. Chem. Ind., 18S6, $, 371. 



CORRECTION OF FLASHING POINT 



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38 MINERAL OILS 

Redwood ^ arrived at the conclusion tliat tlie only satisfactory method 
for the determination of sulphur compounds applicable to all descrip- 
tions of petroleum is that of combustion in oxygen in the Mahler bomb 
and subsequent estimation as barium sulphate ; he recommends that 
2 g. of the sample should be burnt, and that the ox)-gen should be at a 
pressure of 30 atmos. The results obtained are concordant to 
the second place of decimals. A description of the Mahler bomb with 
details of working is given in Vol. I., Part I., in the section on 
"Fuel," p. 256. 

The following method for the determination of the total sulphur in 
kerosene, by means of the Parr calorimeter, has been proposed by 
J. M. Sanders : - — 2-3 g. of the sample are weighed into a 100 c.c. 
porcelain dish, o-oi g. of potassium bromide is dusted over the surface, 
and 4 c.c. of pure fuming nitric acid are added. After the energetic 
reaction has ceased, the dish is heated on the water-bath until the 
liquid becomes dark brown and somewhat viscous. It is then well 
mixed with 05 g. of pure light magnesia, and whilst continuing the 
stirring, is heated over a small flame until the mass shows a tendency 
to solidify on cooling. The granular mass thus obtained is brushed 
into a Parr calorimetric bomb, any trace of oily matter left in the dish 
being removed by warming with a little more magnesia. The standard 
quantity (i measure full) of sodium peroxide is also introduced into 
the calorimeter vessel, and after mixing, the combustion is effected in 
the usual way. A few seconds after firing, the vessel should be 
removed from the water in the calorimeter, and its temperature allowed 
to rise, but not high enough to injure the rubber washer. After about 
45 seconds, the bomb is cooled, opened, and the fused mass transferred 
to 25 c.c. of water in a 200 c.c. nickel beaker, to which the washings are 
also added. The solution is made slightly acid with hydrochloric acid, 
filtered through cotton wool if necessary, boiled to expel chlorine, 
neutralised with ammonia, acidified with hydrochloric acid, and the 
sulphur precipitated as barium sulphate in the boiling solution. The 
method is rapid and the results agree with those obtained by the use 
of the Mahler calorimetric bomb. The construction and use of Parr's 
calorimeter is described in the section on "Fuel," Vol. I., pp. 256-260. 

Good burning oil should not contain more than 002 per cent, of 
sulphur. Commercial oils, even those made from crude Ohio petroleum, 
usuall)' fulfil this condition. E. Hcusler and M. Dennstedt^ have drawn 
attention to the presence of alkyl sulphuric acids in kerosene (due to 
purification by means of sulphuric acid), w^hich, in their opinion, form 
sulphuric acid on combustion, and increase the tendency of the burning 
oil to carbonise the lamp-wick. 

' PelroUum an 1 its ProJuUs, vol. ii., p. 319. - /. Chem. Soc, 1912, lOI, 358. 

* Z. attgew. Chfm., 1904, 17, 264 ; /. Soc. Chem. Ini., 1904, 23, 3 [7. 



KEROSENE. CHEMICAL EXAMINATION 39 

2. The Acid Test. — Properly refined petroleum shaken up with 
sulphuric acid of sp. gr. 1-73 should produce no more than a very slight 
yellow coloration in the acid. 

The official Russian test (Baku section of the Imperial Russian 
Technical Society) is as follows:^ — 100 vols, of oil are shaken for two 
minutes at a temperature not exceeding 32° with 40 vols, of the above 
acid in a stoppered cylinder. The liquid is transferred to a separating 
funnel and the clear acid drawn off into a glass tube, in which its colour 
is compared with that of an equal column of a standard solution of 
Bismarck brown. To prepare the latter, 0-5 g. of Bismarck brown is 
dissolved in a litre of water; a series often standards is then made up 
by mixing i, 2, 3, etc., parts of this solution with 99, 98, 97, etc., parts 
respectively of water, so that the darkest standard (No. 10) contains 
0-005 per cent, of the dye, and the lightest (No. i) 0-0005 per cent. The 
degree of purification is then expressed by the standard number to which 
the sample corresponds. Aqueous solutions of Bismarck brown keep 
fairly well in stoppered bottles. 

It has been found in practice that the lamp oil fraction refined on 
the large scale with 0-5 per cent, of sulphuric acid of sp. gr. 1-84 attains 
as a rule the colour of standard No. 2. With 0-75 per cent, of acid a 
slightly higher degree of purity is obtained, but no further advantage is 
gained by increasing the proportion of acid. The majority of 
commercial oils fall within the range of numbers 1-8. Hence, standard 
No. 8 is considered the limit beyond which an oil must be regarded as 
insufficiently purified. 

3. Determination of Acidity. — 100 c.c. of oil dissolved in neutralised 
alcohol-ether should give with one drop of decinormal alcoholic 
sodium hydroxide a pink colour, phenolphthalein being used as 
indicator. 

4. Salts of Naphthenic and Sulphonic Acids. — The presence of 
these salts, which impair the burning properties of lamp oil, are detected 
by extracting the oil with dilute alkali hydroxide in the following 
manner : — 300 c.c. of the oil are placed in a stoppered 500 c.c. flask with 
18 c.c. of sodium hydroxide solution of sp. gr. 1-014, heated to about 
70° on the water-bath, and thoroughly shaken for one minute. The 
aqueous layer is separated off, cleared by filtration if necessary, and 
divided into two halves. To the first half concentrated hydrochloric 
acid is added, drop by drop, until the liquid is just acid to litmus or 
methyl orange. To the second half exactly the same amount of acid 
is added, and the solution then held immediately over small print. If 
the print can be read without difficulty, the sample may be considered 
free from organic salts ; if not, the ash of the oil should be determined. 
A turbidity does not, however, necessarily prove that naphthenic or 

1 J. Soc. Chem. Ind., 1896, 15, 678. 



40 MINERAL OILS 

sulphonic salts are present, since under the influence of light and 
air petroleum may become sufficiently acid to give a positive indication 
in this test. 

5. Inorganic Residue (Ash). — A litre or half a litre of oil is 
gradually introduced into a retort and distilled off until about 10 c.c. 
are left behind. The residue is washed with petroleum spirit into a 
tared platinum dish, evaporated or burnt off, and finally incinerated at 
a low red heat Good lamp oil should not contain more than 2 mg. of 
ash per litre. 

6. The *' Breaking " of Petroleum. — This phenomenon is due to the 
separation of sodium sulphate or sulphonates from an oil which has 
been standing for a long time. 

LX. UNSATURATED HYDROCARBONS. 

Many petroleums, especially those from Galicia and Roumania, 
contain unsaturated hydrocarbons of the olefinic and benzene series, 
together with cyclic compounds consisting of partly reduced aromatic 
hydrocarbons. 

According to G. Kramer and W. Bottcher and recent experiments of 
M. Weger,^ the quantity of unsaturated hydrocarbons as determined by 
their solubility in concentrated sulphuric acid (p. 21) forms an 
important indication of the quality of a burning oil. 

A characteristic of these hydrocarbons is that they cause the oil to 
burn with a reddish flame. Thus Borneo oil burns badly in ordinary 
lamps, but after the removal of the aromatic hydrocarbons its illuminat- 
ing power equals that of the best American oils. 

X. BURNING QUALITY. 

As a practical test of the value of an oil for illuminating purposes, 
the determination of its burning quality under conditions as near 
as possible to those of ordinary use is of considerable value. 

The following method of carrying out this test is recommended by 
Boverton Redwood.- The oil is burnt in the lamp at a constant 
temperature of preferably 60° F., the wick being raised to yield the 
largest flame obtainable without smoke. A camera is employed 
to register variations in the size and shape of the flame during the test. 
The oil-chambers of the lamps employed should be of uniform 
dimensions, and the burners must be tested to ascertain that they give 
similar flames with the same oils. The wicks employed are examined 
in a special apparatus in which a given length of wick is arranged 
to draw, by means of capillarity, an oil of known quality from a vessel 

^ Chem. Ind., 1905, 28, 24 ; J. Soc. C/iem. Itid.^ 1905, 24, 126. 
2 Petroleum and its Products, vol. ii., p. 21 2. 



KEROSENE. ILLUMINATING POWER 41 

at a fixed temperature ; the value of the wick is judged from the 
quantity of oil drawn out in a certain time, and any defective portion is 
rejected for testing purposes. 

No general agreement has been arrived at as to the extent of 
diminution that should be allowed in a flame classed as of satisfactory 
burning quality, 

XI. ILLUMINATING POWER. 

In its physical principles the photometry of illuminating oils does 
not differ from that of coal gas. A Bunsen photometer fitted with 
Lummer and Brodhun's prismatic device is the best instrument to use. 
A full description of the methods of photometry is given in the section 
on " Illuminating Gas and Ammonia," Vol. II., Part II., pp. 697-716. 

The following points are to be noted with regard to the photometry 
of petroleum : 1 — 

1. Constructio7i of tJie Lamp. — A great deal depends on the construc- 
tion of the lamp in which the oil to be tested is burnt. The mode 
of air-supply, the shape of the chimney and the height of its constriction, 
and the kind of wick employed, are also important factors. It is therefore 
desirable to test an oil as far as possible in a lamp resembling those in 
which it is usually burnt in practice. One and the same kind of lamp 
must, of course, be used for comparative tests of two or more oils. 
Wicks should be dried at 105°, and soaked in the oil whilst still warm. 

Lamps for testing should be provided with capacious oil-wells, 
so that the level of the liquid may change as little as possible during 
burning. 

2. Adjustment of the Flame. — With some oils, notably the Russian 
oils, the burning should be started with a comparatively small flame. 
For the first five minutes the flame is allowed to reach the constriction 
of the chimney, and no further ; it is then gradually raised during the 
first quarter of an hour to the maximum height, that is, until flickering 
or smoking ensues on increasing the height of the flame. The position 
of the constriction should be such that a fully developed flame possesses 
the maximum of illuminating power. For accurate photometric work 
the height of the flame should be measured. 

3. Photometric Measurements are not carried out until the flame has 
burnt at full height for at least half an hour. In accurate work the 
measurements are repeated after 4, 5, 6, etc., hours of burning. 

When an oil contains an undue proportion of fractions boiling above 
270°, its inferior character is only displayed after several hours' burning; 
a marked diminution of its illuminating power then sets in. 

4. Consumptio7i of Oil is determined by weighing the oil-reservoir 
before and after a series of tests. The final results are stated as mean 

^ Eger, Chem. Rev.^ 1899, p. 81. 



42 MINERAL OILS 

photometric intensity, total consumption of oil, and consumption per 
candle-hour. The height and weight of the charred portion of the wick 
are noted, as also odour, etc. 

5. In special cases the residue remaining after half the oil has been 
burnt is submitted to fractional distillation, and the result compared 
with the fractionation of the original oil. 

6. The Standard of Light in England is the Harcourt lo-candle 
pentane lamp, in America the International Standard Candle (since 
April 1909), in Germany the Hefner amyl acetate lamp, and in France 
the Carcel lamp. A comparison of photometric standards and units is 
given in the section on " Ilkiminating Gas and Ammonia," Vol. II., 
Part II., p. 703. 

XII. SOLUBILITY IN ABSOLUTE ALCOHOL. 

Lamp oil is soluble in twice its volume of absolute alcohol, and in 
many cases in less at the ordinary temperature. According to S. 
Aisinman,^ all petroleum fractions with a specific gravity up to 0835 
are miscible with absolute alcohol in all proportions. 

XIII. DETERMINATION OF THE ORIGIN OF A PETROLEUM. 

As it is sometimes of importance to ascertain the origin of a 
petroleum, various investigations have been made with this object 
in view. 

When a drop of bromine is added to 2-3 c.c. of American petroleum 
it is decolorised almost instantaneously, whereas all other oils remain 
coloured for a considerable time. Hence, several determinations have 
been made both of the iodine and bromine values of petroleum. The 
following iodine values were found by E. Graefe :- — 

Iodine value. 
Solar oil (probably a Saxo-Thuringian oil) . . 80 



Russian petroleum 
American petroleum 
Galician petroleum 
Wietze petroleum 



o to 16 

5-5 „ '6-5 
oi 
07 



The following bromine values were determined by F. Utz :^ — 

Source of petroleum. liromine value. 

Russia ...... 072 to 08 

Roumania ...... 0-56 „ o-8 

Austria ...... o-88 

Galicia ...... i-44 

Pennsylvania ..... 2-o 

Petroleum arc-light .... 2-56 

1 Dingl. polyt. J., 1895, 297, 44 ; /• Soc. Chetn. hid., 1895, 14, 812. 

"^ Z. angtw. Chem., I905i 18, 1 580. 

3 Petroleum, 1906, 2, 43 ;/. Soc. Chevt. Ind., 1906, 25. 1 140. 



TRANSFORMER OILS 43 

No definite conclusions can, however, be derived from these figures,^ 
nor can any reliability be placed on the colour test proposed by 
C. Heragen,^ 

Z?.— GAS OILS FROM CRUDE PETROLEUM. 

The oils used for the production of gas are obtained from crude 
petroleum, lignite tar, and shale oil tar. These oils are mobile liquids, 
of a pale to dark yellow colour ; as regards boiling point, they are 
intermediate between burning oil and lubricating oil, i.e. they boil 
between 300" to 400°. They are generally soluble for the most part in 
two volumes of alcohol at the ordinary temperature. Occasionally gas 
oils of lower boiling point are met with, and these are, like petroleum, 
easily soluble in two volumes of alcohol. 

As a rule, i kg. of gas oil yields about 500-600 1, of gas, 300-400 g. 
of tar, and 40-60 g. of coke. 

Further details in regard to gas oils, together with a full account of 
the methods employed for their examination and valuation, are given in 
the section on "Illuminating Gas and Ammonia," Vol. IL, Part II., 
pp. 626-629. 

^.—TRANSFORMER OILS.^ 

The chief requirements for oils used for high-tension electrical 
transformers are freedom from moisture and mineral acids. Further, 
they should exhibit little or no volatility at 100° ; hence, many 
electrical works specify a flashing point of not below 160° (open test). 
When kept for several hours at 100" the oil should show no signs of 
decomposition ; it should remain quite liquid at the lowest winter 
temperature, say — 15°, to which it may be subjected in practice. 

Formerly heavy rosin oil was used for transformers on account of 
Us low price, but to-day the higher petroleum fractions, more or less 
identical with lubricating oils, are preferred. Thus, a good transformer 
oil is specified as follows : — Petroleum distillate of viscosity (Engler) 
9-8 ; sp. gr. 0-8825 ; flashing point 185° ; loss after five hours' exposure to 
100° in Archbutt apparatus (see p. 74), o-o6 per cent, and after two hours 
at 170°, I per cent. Some electrical works stipulate a viscosity not 
exceeding 8 (Engler) at 20^ 

Rosin oils are considerably more volatile at 100" and 170° than 
heavy or even light petroleum lubricants. After five hours at 100° rosin 
oils lose 0-4 to 0-8 per cent. After two hours at 170° thick rosin oils lose 

' Cf. F. Schwarz, Mitt. Kg/. Materialpriifungsamt. Gross-Lichterfelde, 1909, 27, 25 ; /. Soc. 
Chem. Ind., 1909, 28, 467. 

2 Chem. Zeit.y 1909, 33, 20 ; J. Soc. Chem. Inc/., 1 909, 28, 83. 

^ Cf. K. Duckham, Electrician, 191 1, 67, 212 ; F. Breth, Petroleum, 191 1, 7, 290 ; A. Beringer, 
Mitt. K.K. Tech. Gewerb. Museum, Vieuna, 191 1, 21, 211 ; y. Soc. Chem. Ind., 1912, 31, 1 14. 



44 MINERAL OILS 

5-6 to 7-4 per cent. Light lignite oils show much higher losses at ioo°, 
and are therefore unsuitable for use with transformers. 

Those machine oils derived from petroleum which have a flashing 
point of over i6o° (open test) with a volatility of less than oi per 
cent, in five hours at lOO", provided they satisfy the electrical require- 
ments, are suitable for use in transformers. Rosin oils do not meet 
these requirements. 

Oils serving as high-tension switch insulators must be free from 
moisture and acid, and must above all be practically non-volatile, so as 
not to be liable to catch fire from a spark. Cylinder oils are the best 
adapted to this purpose. 

Transformer oils are tested for electrical insulating properties, not 
by determining the ordinary insulation resistance, but by measuring 
the E.M.F. requisite to send a spark through a column of oil of 
definite length. A spark gap is set up within a cylindrical glass vessel 
of about 200 c.c. capacity and 3 cm. diameter containing the oil, and 
the E.M.F. is raised until a spark passes. The terminals must be 
polished spherical knobs, and their distance apart must be kept fixed. 
Bubbles of water or air and floating fibrous matter affect the results 
very seriously. 

7?:— LIQUID FUEL FOR INTERNAL COMBUSTION ENGINES. 

Petroleum distillates of all grades — from the light petrol to heavy 
fuel oils— form the principal liquid fuels emplo)'cd in internal com- 
bustion engines. In addition, coal-tar oils, lignite-tar oils, and even 
crude tar are used to a small extent in the most modern forms of 
Diesel engine. 

For high speed motors petrol is the usual fuel. With the spray 
carburettors now employed heavier grades of petrol are serviceable ; 
the average specific gravity is about 072. Many modern carburettors 
are capable of giving a good mixture with air with petrol of higher 
density, that of sp. gr. 076 being employed for motor-bus vehicles and 
others of similar type. The gross calorific value of petrol is about 
11,100 calorics per pound ; the net value 10,200 calories. 

The specific gravity alone is but a rough guide to the character of 
the petrol. A distillation test should be conducted to ascertain the 
various fractions over given ranges of temperature. A good petrol of 
sp. gr. 071 will }icld nearly 80 per cent, below 120", and 90 per cent, 
below 140". 

Benzene (90 per cent, benzol) is an efficient substitute for petrol. 
In many cases the two liquids are employed, mixed in various pro- 
portions. The calorific value of benzol is 9900 calories gross, and 9500 
calories net per pound. 



HEAVY FUEL OILS 45 

In slow speed oil engines ordinary kerosene is employed on a large 
scale. Owing to its low vapour tension at ordinary temperatures, the 
kerosene has to be vapourised by heat before admixture with air. 

The Diesel engine, with the semi-Diesel type which followed the 
introduction of the Diesel principle, are not dependent on the formation 
of an explosive mixture, but on the steady combustion of a fine oil 
spray through a great portion of the working stroke. The introduction 
of this type of engine has extended enormously the range of liquid 
fuels available for power. 

Heavy petroleum oils are employed usually, but the very great 
advantage of being able to use coal-tar and lignite-tar oils cannot be 
overestimated in countries depending on foreign supplies for all 
petroleum products. With the latter oils a small quantity of a 
petroleum oil is injected by an independent pump, to serve as the 
means of ignition of the coal-tar oil forming the major bulk of the 
fuel. Since a fine spray has to be produced, it is essential that the tar 
or tar oil shall contain but little free carbon. 



(7.— FUEL 'OILS (MASUT, ASTATKI).i 

Crude oils, liquid still-residues (Masut), tar residues, cheap lignite tar 
oils, etc., are largely used, where economic considerations permit, for 
steam-raising purposes under locomotives, marine engines, and other 
boilers. The oils must be atomised by some suitable injector, these 
being operated either by steam, air under pressure, or by forcing the 
heated oil under pressure through special atomisers. 

The examination of fuel oils consists essentially in the determination 
of the calorific value and the specific gravity. The flashing point is also 
invariably determined on account of safety in use. In the British 
Mercantile Marine oil is not permitted for fuel purposes unless the 
flashing point is above 150'' F. 

The calorimetric value is determined in a Berthelot, Krocker, or 
Mahler bomb (see Vol. I., Part I., p. 254) ; it can also be calculated from 
the elementary composition by means of the following formula given by 
Mendelejeff : — 

Q = 8iC-f30oH + 26(0-S). 

According to the revised Admiralty specification ^ (1912) for oil 
fuel the flashing point shall not be lower than 175° F., close test, Abel 
or Pensky-Martens. (In the case of oils of exceptionally low viscosity, 
such as distillates from shale, the flashing point must not be less than 

^ Cf. Zaloziecki and Lidow, Naphtha, 1904, Nos. 21, 22. 
^ Cd. 7010, J. Soc. Chetn. Ind., 1913, 32, 859. 



46 MINERAL OILS 

200' F.) The proportion of sulphur contained in the oil shall not 
exceed 300 per cent. The oil fuel supplied shall be as free as possible 
from acid, and in any case the quantity of acid must not exceed 005 
per cent., calculated as oleic acid when tested by shaking up the oil 
with distilled water, and determining by titration with decinormal alkali 
the amount of acid extracted by the water, methyl orange being used 
as indicator. The quantity of water delivered with the oil shall not 
exceed 05 per cent. 

The viscosity of the oil supplied shall not exceed 2000 seconds for 
an outflow of 50 c.c. at a temperature of 32' F., as determined by 
Sir Bovcrton Redwood's standard viscometer (Admiralty type for 
testing oil fuel). The oil supplied shall be free from earthy, car- 
bonaceous, or fibrous matter, or other impurities which are likely to 
choke the burners. 

^—DUST-LAYING OILS. 

The most suitable dust-laying oils for roads are crude oils, heavy 
asphalt oils, oily by-products, tars, liquid asphalt, and emulsions of oils 
and water (Westrumite). Raschig has recently proposed a mixture of 
tar and clay under the name of "Kiton." 

An extensive series of dust-laying oils was investigated by R. 
Heise,^ who concluded that the so-called water-soluble oils (see 
p. 102), which are diluted with water before use, are not to be recom- 
mended. Thin pure mineral oils are considered by him to be the 
most efficient 

Dust-laying oils used for wooden floors and linoleum should be pure 
mineral oils of high specific viscosity, and should give no separation of 
sticky substances in the course of a few weeks. 

/.—PARAFFIN WAX. 

Crude paraffin wax or paraffin scale always contains some of the 
high-boiling hydrocarbons from which it has crystallised on cooling. 
The "scale" is subsequently refined to form the paraffin wax of 
commerce. 

Hard paraffin wax for the manufacture of candles should melt at 
about 50.° Soft paraffin wax, prepared by cold-pressing comparatively 
light oils, melts at about 30", and is used for impregnating textiles, etc., 
and as an addition to hard candle-paraffin. 

The examination of hard paraffin wax is described in the section 
on " Special Methods employed in the Oil and Fat Industries," this 
Vol., p. 179. 

' Arbeiten aus d. Kais. GesundkitisamI, 1909, 30, part i. 



TAR AND PITCH RESIDUES 47 

Paraffin Scale ^ contains various quantities of impurities or "dirt" 
(fibres of press-cloths, sand, etc.), water, and hydrocarbons of low 
melting point termed " oil," which consists chiefly of" soft paraffin." 

Determination of " Dirt." — A weighed quantity of the sample is 
melted, allowed to subside, the clear paraffin wax poured off, the 
residue mixed with naphtha or petroleum spirit, the whole transferred 
to a tared, dry filter paper, washed with the solvent used, dried, and 
weighed. 

Determination of Water. — The scale is strongly heated in a copper 
flask connected with a condenser, and the distillate collected in a 
narrow graduated measure in which the volume of water that has 
distilled over is read off. A little light oil distils over with the water. 
The condenser tube must be washed out with naphtha or petroleum 
spirit (previously saturated with water), as a little water usually adheres 
to the sides. 

Determination of Oil. — A quantity of the scale, freed from water and 
dirt by melting and subsidence, is allowed to cool overnight to a 
temperature of 15°, the solid residue ground to powder, and a portion 
treated in a press provided with a pressure gauge to express the oil. 
For this purpose the sample is wrapped in fine linen press-cloth and a 
sufficient number of layers of filter paper to absorb all the oil. 

These methods for the examination of paraffin scale, which have 
been agreed upon by the Scottish Mineral Oil Association, have 
been described with full details by J. S. Thomson.^ 



^.— TAR AND PITCH RESIDUES. 

{Petroleum Tar, Asphalt, and Pitch.) 

In the distillation of crude oil a variety of dark-coloured residues 
are obtained which are used as paving asphalt, lubricants, or as raw 
materials for the same, and also for a number of other purposes. The 
more fluid of these residues are sometimes sold directly as cylinder oils ; 
others, which only just melt on the water-bath, may be worked up by 
"cracking," often with a yield of more than 50 per cent, into dark 
lubricating oils. 

In the examination of these products the testing of their viscosity 
affords no useful criteria. Their value depends on their softening- point 
and melting point. The melting point is best determined by G. 
Kraemer and S. Sarnow's method, which is fully described in the 
section on "Coal Tar," Vol. II., Part II., p. 837. The results obtained 

^ Cf. Lewkowitsch, Chemical Technology and .Analysis of Oils, Fats, and Waxes, 4th ed., 
1909, vol. iii., p. 211. 

^y. Soc. Chem. Ind., 1891, 10, 342. 



48 



MINERAL OILS 



by this method are consistent in themselves, but, of course, differ for a 
given substance from the melting point as taken by the capillary tube 
method. This is illustrated by the following data : — 



Table 13. 







Melting point. 


Material. 


Kraemer and Sarnow's 
metlicxi. 


Capillary tube 
method. 


Ceresin .... 

Beeswax 

Paraffin wax . 

Rosin .... 

Asphalt (refined) . 

Asphalt (brittle) . 

Petroleum pitch (Alsatian) 




52° 

55° -5 

46° 
67° to 67°-5 
51° -5 to 52° 

82° 

105° 


47° to 53° 

61°-5 „ 63°-5 

45° „ 48° 

Indefinite 

11 

»i 

11 



For the determination of the specific gravity, if it be desired only to 
ascertain whether this is greater or less than i-o, a fairly large quantity 
of the sample is melted and a drop or two allowed to fall into a beaker 
of water at 15°; air-bubbles, if present, must be removed with a feather. 
For accurate determinations a pyknometer is used. 

For the estimation of the content of Paraffin Wax the products 
must first be refined. This is carried out in the same manner as in 
the jexamination of ozokerite (p. 55). The paraffin wax is then 
determined by the method described on p. 179. 

The recognition of the presence of Fat Pitches, such as are obtained 
in the candle, wool-fat, etc. industries, is rendered easy by their contain- 
ing, as a rule, besides hydrocarbons, notable proportions of fatty acids 
and esters, which are, of course, absent from petroleum. Very hard 
fat pitches, however, obtained by pushing the distillation to the utmost 
limit, only contain small proportions of fatt)' acids and esters. The acid 
value and the saponification value of these compounds are determined 
by the methods described in the section on " Oils, Fats, and Waxes," 
this Vol., pp. 122 and 1 14. 

The subjoined Table gives an indication of the values obtained with 
" Stearine Pitch," and " Petroleum Pitch," respectively : — 

Table 14. 





Stcarine 
pitch. 


Petroleum 
pitch. 




Stearine 
pitch. 


retroleuni 
pitch. 


Acids values - 


0-2 
1-0 
2-4 
2-9 
4-0 


01 
0-3 
0-3 
1-2 


f 

Saponification 
values 


2-2 
2-4 

4-3 

8-3 


1-3 
1-8 
1-7 
2-6 
1-1 



TAR AND PITCH RESIDUES 49 

When soft fatty pitches are destructively distilled considerable 
quantities of fatty acids are found in the distillate, especially in the 
first runnings. In the case of hard pitches only the first drops that 
distil over contain notable amounts of acids ; the yield of acids can, 
however, be considerably increased by distilling with the aid of super- 
heated steam at 300^ The distillate from lignite pitches, on the 
contrary, contains only minute proportions of acids. 

The detection of IVood-tar PitcJi is facilitated by the characteristic 
smell of creosote, and by its almost complete solubility in absolute 
alcohol and in glacial acetic acid, in which petroleum pitch and fat 
pitches are, for the most part, insoluble. According to E. Donath and 
B. Margosches,^ wood-tar pitch differs from all other pitches by its 
sparing solubility in carbon tetrachloride. 

Coal-tar Pitch may be detected by the presence of a considerable 
amount of free carbon. The best method, however, is to distil the 
sample destructively and to estimate the anthracene in the distillate by 
Luck's method, as described in the section on "Coal Tar," Vol. II., 
Part II., p. 805. 

The detection of Petroleum Pitch in Natural Asphalt is frequently 
required. The following method proposed by J. Marcusson and 
Eickmann ^ can be employed for this estimation : — 

30 g. of the sample are dissolved in 45 c.c. of benzene in a small 
flask under a reflux condenser, and the solution poured into 600 c.c. of 
petroleum spirit boiling below 80° ; the flask is rinsed out with 50 c.c. 
of petroleum spirit. After standing for some time the solution is 
sucked off" from the asphaltic precipitate, and the filtrate shaken three 
times successively with 45 c.c. of concentrated sulphuric acid in a 
separating funnel to remove all asphaltic substances. It is then 
further shaken with a N\\ solution of alkali in 50 per cent, aqueous 
alcohol and then several times with water, and finally evaporated, dried 
for ten minutes at 105°, and weighed. 

The following data may furnish some guidance in the interpretation 
of the results so obtained : natural asphalt gave 1-4-31 per cent, of oily 
matter, yellow-brown to brown in colour, and distinctly liquid at 20° ; 
paraffin wax appeared to be absent, since on cooling the alcohol-ether 
solution to - 20°, only tarry, transparent substances separated out. 
Petroleum pitch, on the other hand, gave 26-58 per cent, of oily 
matter of a green to greenish-black colour, which was not liquid at 20° 
but pasty (sometimes almost liquid and sometimes very viscous), with 
solid particles; the content of paraffin wax amounted to 3-3-i6-6 per 
cent. 

If the quantity of petroleum pitch present is large, it is recommended 

1 Chem. Ind., I904, 27, 220 ; J. Soc. Chem. Ind., 1904, 23, 541. 

2 Chem. Zeit., 1908, 32, 965. 



50 MINERAL OILS 

to distil the pitch destructively, and if small, to distil the oil)' substances 
dissolved by petroleum spirit, and to determine the paraffin wax in the 
distillate. 

The detection of petroleum asphalt in natural asphalt may also be 
based on the comparatively high percentage of sulphur usually found 
in the latter, which varies from 2-10 per cent. 

The above method will be found useful in the examination of 
Asphalt Substitutes, consisting of mixtures of powdered limestone and 
petroleum pitch. For this purpose it is necessary to first extract the 
bitumen, which is effected as follows: — 

From 2-5 g. of the finely powdered air-dry material arc boiled in a 
conical flask under a reflux condenser with 100-200 c.c. of benzene. 
The flask is allowed to stand overnight in a slanting position, and the 
main portion of the clean supernatant liquid is poured off into a second 
conical flask which is also kept in a slanting position. The solid residue 
is shaken up with a fresh quantity of benzene, which is allowed to settle 
as before, and decanted, on the same day, into the second flask. This 
is allowed to settle overnight, and the clear benzene solution is then 
finally run off and distilled. The residue is dried at 105' in a tared 
dish, and weighed. A further quantity of bitumen is extracted from 
the solid residue by decomposing it with hydrochloric acid and shaking 
up with benzene. From the total soluble bitumen thus obtained the 
mineral ash, as determined by incineration, is subtracted. The nature 
of the soluble bitumen is then examined. 

An alternative method for the extraction of the bitumen has been 
proposed by A. Prettner.^ 

Z.- BY-PRODUCTS OF THE PETROLEUM INDUSTRY. 

BY-PRODUCTS OF THE REFINING OPERATIONS. 

1. Acid Tar. — The acid tar which separates from, the concentrated 
sulphuric acid, used in refining, by dilution with water consists chiefly 
of resinous substances of unknown composition. It also occludes free 
sulphuric acid and sulphonic acids. Their determination, which is, 
however, very rarely required, may be carried out by the methods 
described under "Turkey Red Oils," in the section on "Special Methods 
employed in the Oil and Fat Industries," this Vol., pp. 170 et seq. 

2. Pitch. — This is examined for the melting point and ash, as 
described in the section on " Coal Tar," Vol. II., Part II., pp. 836 ct scq. 

3. Waste Acid. — This consists of the dilute acid separated from the 
acid tar, and is valued by the determination of the proportion of actual 
acid contained. 

' Chem. Zeit., 1909, 33. 917, 926 ; /. Soc. Chem. Ind., 1909, 28, 983. 



SHALE AND LIGNITE OILS 



51 



J/.— PRODUCTS OF THE SHALE AND LIGNITE INDUSTRIES. 

By the destructive distillation of shale and of lignite, tars are 
obtained which yield crude oils on distillation. These are treated 
similarly to crude petroleum, and are worked up into naphtha, burning 
oil, gas oil, and paraffin wax. * 



EXPERIMENTAL DISTILLATION TEST. 

The yield of oil which a bituminous shale or lignite will give 
is determined by an experimental distillation test. 

Scotch oil-shales show considerable differences in the yield of oil. 
The richer shales yield about 30 gallons of oil per ton of shale, and in 
some cases as much as 40 gallons, and average about 73 per cent, of 
mineral matter; Broxburn shale yields 12 per cent, of crude oil, 8 per 
cent, of water, 9 per cent, of coke, 4 per cent, of gas, and 6"] per cent, of 
mineral residue. A high-grade lignite yields approximately 10 per 
cent, of tar, 52 per cent, of water, 32 per cent, of coke, and 6 per cent, of 
gas, including loss. The bituminous shale of Messel (near Darm- 
stadt) yields 6-10 per cent, of tar, 40-45 per cent, of water, and 40-50 
per cent, of residue. 

A laboratory distillation, although of limited value in estimating the 
yield obtainable on a large scale, is frequently serviceable. The following 
method of carrying out the test is recommended : — 

A tared retort of refractory glass, holding 150-200 c.c, is connected 
with a water-cooled receiver fitted with 
an exit tube, as shown in Fig. 14. 
From 20-50 g. of the pounded sample 
are heated, at first with a small and 
finally with a full flame, as long as any 
vapours condense. The gases issuing 
from the receiver are tested with a 
flame from time to time; if the distilla- 
tion is properly conducted (over four to 
six hours) they should either not be 
inflammable, or only burn weakly and fitfully. The distillate, 
consisting of turbid water and tar, is weighed. The tar which has 
condensed in the neck of the retort is melted and run down into 
the receiver ; the latter is then placed in hot water, and some hot 
water poured into it, so that all the tar may collect on the surface. 
After cooling, the solidified tar is broken up, after the water has 
drained ofl". The lumps are dried preliminarily with rolls of filter-paper, 
then air-dried, and weighed. It is safer to extract the tar by means of 
benzene, and then to evaporate and weigh the residue. To translate 




Fia. 14. 



52 MINERAL OILS 

laboratory yields into working yields they must be diminished by a 
large factor, sa}' by 30-40 per cent., according to the conditions of 
manufacture. (Lignite tar as produced in works is less acid and 
specifically lighter than the laboratory product.) 

As an alternative to this method, a metal retort and a considerably 
greater quantity of the sample may be used for the initial distillation. 

I. Shale Oil.^ 

The manufacture of paraffin and paraffin oil by the destructive 
distillation of shale was initiated by James Young in 1851. A highly 
bituminous mineral known as Boghead coal or Torbanehill mineral was 
first used, from which a yield of 120 to 130 gallons of crude oil per ton 
was obtained ; the supply of this mineral was, however, exhausted 
within a k\v years, and the shales now employed in Scotland, which is 
the chief centre of the industry, are those found between the Coal- 
measures and the Old Red Sandstone. 

This oil-shale, which is dark grey or black in colour and has a 
specific gravity of about i-75, is distilled at a comparatively low tempera- 
ture. Horizontal retorts were at first employed for the distillation, but 
vertical retorts and continuous methods of distillation in presence of 
superheated steam have since been introduced by Young, Henderson, 
and Beilby, whereby increased efficiency and control of the conditions 
of working have been effected. 

Crude shale oil has a specific gravity of o-86o-o-900, and solidifies 
at the ordinary temperature ; it consists of 70-80 per cent, of paraffins 
and olefines, small quantities of benzene hydrocarbons and naphthenes, 
a small proportion of phenol and cresols, and a larger proportion of 
basic constituents (pyridine, etc.). The refining process comprises 
fractional distillation, together with treatment with acid and alkali ; 
the solid paraffin is separated from the portion of the oil, the specific 
gravity of which is above 0840, by cooling and cr)-stallisation. The 
commercial products thus obtained vary with the nature of the mineral 
and the process of distillation adopted ; they may be classified under 
the following headings : — 

Sp. gr. 

Gasoline ...... o-6oo to 0-690 



Naphtha or shale spirit 
Burning or paraffin oil 
Medium or light mineral oil 
Lubricating oil 



0700 „ 0760 
0760 „ 0-840 
0-840 „ 0-870 
0S65 „ 0-910 

M.P. 

Paraffin wax or " scale " . . . . 43° to 60° 

' C/. B. Redwood, Petroleum and its Products, 3rd ed., 1913, vol. ii., pp. 83 etseq.\ I. L 
Redwood, Mineral Oils and their By-Producis ; W. Scheithauer, Shale Oils and Tars and their 
Products, English translation by C. Salter ; also "The Oil-Shales of the Lothians," Memoirs 
of the Geological Survey^ Scotland, 191 2. 



LIGNITE TAR 53 

Gasoline and naphtha contain from 60-70 per cent, of defines and 
other hydrocarbons acted upon by fuming nitric acid, burning oil from 
30-80 per cent. ; lubricating oil consists almost entirely of olefines. 

B. Redwood^ gives the following examples of the average )'ield of 

commercial products obtained at two of the principal Scottish refineries 

in 1895 ; the grouping of the fractions is somewhat different in the two 

cases : — 

I. II. 

Gasoline"* 

NaphthaJ " 

Burning oils 

Intermediate and heavy oils 

Lubricating oils . 

Paraffin scale 

Paraffin (refined or semi-refined) 

Loss 



6-09 


3.0 


31.84 


39-0 


23-97 


« • • 


• • • • 


i8-o 


13-53 


• • • 


. 


lO-O 


24-57 


30-0 


I GO-GO 


lOO-CK 



The distillation of the bituminous shales of New Brunswick, Canada, 
and of the United States has been investigated by C. Baskerville.- 

The Examination of Shale Oil and of Shale Oil Products. 

The methods of examination described in connection with petroleum 
are applicable to the corresponding products from shale oil. These 
comprise the determination of the specific gravity, the solidifying point, 
the distillation test, the flashing point, the burning quality, the illumin- 
ating value, and the content of " paraffin scale " and paraffin wax. 

The Solidifying Point of the crude oil is determined by dipping a 
thermometer into the oil, previously heated to 6o°-70°, then withdrawing 
it and allowing to cool ; the temperature at which the drop adhering to 
the bulb of the thermometer is seen to solidify is taken as the solidify- 
ing point. This point is higher the greater the percentage of paraffin 
present. 

The methods for the determination of Paraffin " Scale " and of 
Paraffin Wax are described in the section on " Special Methods 
employed in the Oil and Fat Industries," this Vol., p. 179. 

II, Lignite or Brown Coal Tar.^ 

The distillation of brown coal or lignite forms an important industry 
in Germany ; it is not carried on in this country, nor in the United 
States. The methods of distillation are similar to those employed in 
the case of shale, and the resulting tar is fractionated and purified for the 
preparation of commercial products on analogous lines. 

^ Petroleum and its Products^ vol. ii., p. 124. 

2 Eng. and Min.J., 1909, 88, I49, 195, and 501 ; /. Soc. C/ietn. /nd., 1909, 28, 878. 

^ Cf. B. Redwood, Petroleum and its Products ^ vol. ii., pp. 124 ei seq. 



54 MINERAL OILS 

At the ordinary temperature lignite tar is a butter-like mass, yellow 
to brown in colour, and having a smell of creosote and often of 
sulphuretted hydrogen. The solidifying point ranges from i5'-3o°; it 
begins to boil between 80° and loo^and the bulk of the distillate comes 
over, as a rule, between 250 and 350'. 

The tar consists mainly of saturated and unsaturated hydrocarbons, 
of which the former predominate. Owing to the higher proportion of 
unsaturated hydrocarbons as compared with shale oil the iodine values 
both of the crude oil and of the paraffin wax obtained from lignite are 
higher, and amount to 70 and 9 respectively. Other constituents of the 
tar which are present only to a small extent are phenol, cresols, benzene 
and its homologues, naphthalene (o-i-o-2 per cent.), chrysene (Ci^Hj.,), 
and picene (Co.>HjJ ; and in very small quantities, aldehydes, ketones, 
pyridine bases, quinoline, carbon bisulphide, thiophene and mercaptans. 

The Examination of Lignite Tar is conducted similarly to that 
of shale oil, and the products obtained therefrom are tested in an 
analogous manner. 

For the Distillation Test of the Crude Tar, about 200 g. are distilled 
from a retort. The first runnings, up to the point when a drop 
crystallises on being cooled with ice, are collected and weighed as light 
oil, and the subsequent fraction, until reddish resinous matter begins to 
distil, represents crude paraffin wax ; the ensuing picene fraction is 
collected separately, the residue of coke in the retort weighed, and 
the gaseous products plus loss taken by difference. 

Examination of Gas Oil. — This forms an important fraction of lignite 
tar. It should be practically free from creosote, which is ascertained by 
shaking 100 c.c. of the oil with 100 c.c. of sodium hydroxide solution of 
sp. gr. 1-05 for five minutes and measuring the decrease in volume. The 
oil should also be free from sulphur. For the Distillation Test fractions 
are collected at intervals of 50^ ; the greater the proportion of the 
sample that distils below 300" the greater is its value as a gas oil. 

in. Montan Wax. 

Montan Wax was first prepared by E. von Bogen ^ from the 
bitumen extracted from dried Thuringian lignite by means of volatile 
solvents or from freshly mined lignite by treatment with superheated 
steam. The resulting product is redistilled repeatedly with superheated 
steam, and finally distilled in a vacuum. It is used chiefly as a Carnaliba 
wax substitute in the manufacture of polishes, and as an insulating 
material in place of ceresin. 

The wax forms a hard, white mass, which melts above 70°, and 
consists of a mixture of fatty acids and a hydrocarbon. The acid 

1 Gcr. P.its. ior373 ; 1 16453; Eng. Pat., 5999(1900). /. Soc. Chem. Ind., 1900, 19, 728; 
Z. angew. Chem., 1901, 14, llio ; /. Soc. Chem. Ind., 1901, 20, 1221. 



OZOKERITE AND CERESIN 55 

" Montanic acid" melts at 80°, and has a sp. gr. of 0-915 ; the hydro- 
carbon is a saturated compound, melts at 58°-59°, and has a sp. gr. of 
0-920. The latter is readily carbonised on heating with concentrated 
sulphuric acid, a reaction which differentiates it from paraffin wax. 

A sample of Montan wax examined by H. Ryan and T. Dillon,^ 
which was of a yellowish colour, had a melting point of 76°, an acid 
value of 73-3, a saponification value of 73-9, and an iodine value (Hiibl- 
Waller) of 16-0. It yielded 47 per cent, of unsaponifiable matter and 
53 percent, of crude montanic acid. The latter had an acid value of 
138-3 and consisted in the main of an acid, CogH^gOo, with a molecular 
weight of 432 and a smaller quantity of an acid of lower molecular 
weight. The unsaponifiable matter had an acid value of 31-3 ; from its 
elementary composition it did not appear to be a pure hydrocarbon, but 
was free from hydroxylic constituents. 

Montaniji Wax is a similar product to Montan wax, but differs 
greatly in its physical properties.^ 

iV.— OZOKERITE AND CERESIN. 

Ozokerite is a naturally occurring bituminous product which is 
found in several localities in the vicinity of petroleum springs. The 
best-known product is that from Galicia ; it is also found in Roumania, 
Utah, the Argentine, and the Orange River Colony.^ 

Crude ozokerite varies in colour from yellow to dark brown. The 
specific gravity varies from 0-91-0-97; the melting point depends upon 
the proportion of liquid hydrocarbons, and it is accordingly difficult to 
fix a lower limit, but an upper limit of 100° may be accepted. It is 
purified from mineral matter, clay, etc., by a liquating process and by 
boiling out with water, and then consists chiefly of h}'drocarbons 
together with oxygenated and wax-like substances. Fraudulently 
added impurities comprise asphaltum (mineral pitch) and residues 
from paraffin-oil distilleries. 

In the examination of ozokerite the loss on heating to 150° (which 
should not exceed 5 per cent.), the melting and solidifying points, and 
the proportion of mineral matter should be determined. For the 
estimation of the mineral contents small pieces are cut from the bottom 
of the blocks and extracted with petroleum spirit. 

A reliable valuation of ozokerite can be effected by closely following 
the method of refining as adopted on the large scale. 

The following method for the commercial valuation of ozokerite is 
recommended by B. Lach:^ — 100 g. of the sample are treated in a 
tared porcelain basin with 200 g. of fuming sulphuric acid at a 

^ Proc. Roy, Dublin Soc.^ 1909, 12, 202 ; J. Soc. Chem. Ind., I909, 28, 878. 
^ C/". J. Berlinerblau, Das Erdwac/is, Ozokerit und Ceresitt, 1 897. 
' C/ietn, Zeit., 1885, 9, 905 ; /. Soc, Chem. Ind,, 1885, 4, 488. 



56 MINERAL OILS 

temperature of 1 70^-1 80°, with constant stirring, until sulphur dioxide 
ceases to be evolved, and the basin then allowed to cool, and weighed ; 
the loss in weight represents the sum of the water and hydrocarbons. 
The residue is then melted and 10 g. of animal charcoal, previously 
dried at 140°, stirred in. A tenth part of this mixture is weighed off in 
a paper thimble, extracted in a Soxhlet thimble with petroleum spirit 
boiling below 80°, and the filter dried at 130'^ and weighed; this gives 
the content of ceresin. This result may be checked by evaporating the 
petroleum spirit solution and drying the residue at 180''; the melting 
point of the residual ceresin is then determined. The proportion of 
fuming sulphuric acid used may be varied according as the colour of 
the refined product is desired to be yellow or white. 

According to E. von Boyer,^ 5 g. of the sample is sufficient for a 
technical analysis. 

Ozokerite is exclusively worked up to-day for the preparation of 
Ceresin. For this purpose it is heated with sulphuric acid, with 
constant stirring, decolorised with charcoal, and filtered through a filter- 
press. The cakes thus obtained are then treated with volatile solvents 
to extract the contained ceresin. The methods of the examination of 
ceresin are described in the section on " Special Methods employed in 
the Oil and Fat Industries," this Vol., p. 187. 

C>.— ICHTHYOL. 

By the dry distillation of the bituminous shales containing fossil 
fish found at Seefeld in the Tyrol, a crude volatile oil is obtained, 
which when treated with an excess of concentrated sulphuric acid and 
subsequently neutralised by ammonia yields the product known as 
" Ichthyol," the ammonium salt of ichthyol sulphuric acid. It has 
been frequently stated to be a definite compound of the composition 
C23H3gS30c(NHJo, but it has been definitely proved by F. W. Passmore,^ 
from its behaviour towards solvents, that this is not the case ; the 
sulphur is present both as sulphonate and sulphate, and in addition 
a portion is derived from the original oil previous to sulphonation 
(" sulphidic " or non-oxidised sulphur). 

According to Passmore, ichthyol contains 10-72 per cent, of total 
sulphur, of which 594 per cent, (reckoned as ammonium sulphate) is 
present as mineral sulphates. From these figures and other data he 
calculates the total organic sulphur on the dry organic residue as i8-66 
per cent, and that of the "sulphidic" sulphur as 12-51 per cent. 

Passmore has also published analyses of a number of preparations 
of a similar character to ichthyol which have been introduced for 
medicinal purposes under various trade-names, such as, " Ichthynat," 

1 Z. angew. C/iem., 1898, 17, 383 ; /. Soc. Chem. /nd., 1898, 17, 609. 

2 Chem, and Drug., 1909, 75, 935. 



PEAT TAR 57 

'• Ichtosan," " Isurol," etc. ; these contain from i2-go-i6-66 per cent, of 
organic sulphur, and from 4-oy-g-ii per cent, of "sulphidic" sulphur, 
calculated as above on the dry organic residue. 

Ichthyol and the allied preparations are used in medicine chiefly for 
the external treatment of skin diseases, such as chronic eczema, and as 
internal antiseptics. 

Properties of Ichthyol. — Ichthyol in the form of the ammonium 

salt is a reddish-brown viscid liquid with a bituminous odour and taste. 

It is soluble in water, glycerine, oils, fats, and vaseline. Treated with 

potassium hydroxide, ammonia is liberated, and the mixture after 

drying and igniting gives off sulphuretted hydrogen when treated with 

hydrochloric acid. When dried on a water-bath it loses about 45 per 

cent, of its weight. 

P. -PEAT TAR. 

In the peat-distilling industry, peat is either distilled right down to 
coke, which is used in metallurgical operations, or it is only partially 
carbonised so that the residue may be employed as a household or 
industrial fuel. The distillates obtained contain respectively 4 or 2 per 
cent, of tar; 40 or 36 per cent, of products soluble in water, consisting of 
ammonia, methyl alcohol, and acetic acid; and 21 or 12 per cent, of 
gaseous products. 

To carry out an experimental distillation on the laboratory scale, 
about 500 g. of the sample are distilled from an iron retort ; the works 
yield of tar may be taken as 70 per cent, of that obtained in the 
laboratory test. A good peat should not contain more than 6-8 per 
cent, of ash. The tar contains a considerable proportion (30-40 per 
cent.) of creosote. 

Literature. 

AlsiNMAN, S. — Taschenbuch fiir die Mineralol-Industrie, 1896. 

Benedikt, R., and Ulzer, F. — Analyse der Fette und IVachsar/en, 1903. 

Berlinerblau, J. — Erdwachs, Ozokerit und Ceresin, iSgy. 

Engler, C, and HoFER, H. — Das Erd'dl, 191 1. 

Graefe, E. — LaboratoHumsbuch fiir die Braunkohlenteerindustrie, 1908. 

HOLDE, D. — Untersuchung der Miner aid I e und Fette, 3rd edition, 1909. 

Kohler, H. — Chemie und Technologie der Natiirlichen und Kilnstlichen Asphalte, 

1904. 
Lewkowitsch, J. — Chemical Technology and Analysis of Oils, Fats, and Waxes, 

4th edition, 1909. 
RakusiNj M. A. — Die Untersuchung des Erdols und seine Prodiicte, 1906. 
Redwood, Boverton — Petroleutn and its Products, 3rd edition, 1913. 
Redwood, I. I. — Mineral Oils and their By-products, 1897. 
SCHEITHAUER, W. — Fabrikation der Mineralole und dcs Paraffins aus Schwelkohle, 

1895. 
SCHEITHAUER, \N ,— Shale Oils and Tars and their Products, English translation 

by C. Salter, 19 13. 
Veith, a. — Industrie der Mineralole, 1902. 
WiSCHiN, R. A. — Die Naphthene, 1901. 



LUBRICANTS 

By Prof. D. HOLDE, Ph.D., Divisional Director of the Royal Testing Laboratory, 
Gross-Lichterfelde, Berlin, in collaboration with G. Meverheim, Ph.D. 
English translation revised by the late J. Lewkowitsch, M.A., Ph.D.i 

The substances used as lubricants may be classified as follows: — 

(a) Mineral Lubricants. — Owing to their cheapness and to certain 
technical advantages possessed by them, mineral oils enjoy at present 
by far the widest application. In Western Europe they are imported 
mainly from America and Russia, to a smaller extent from Galicia and 
Austria-Hungary ; lubricants are also obtained as one of the products 
of the Scotch shale-oil industry. Germany produces about one-fifth of 
its consumption from native material, chiefly from Wietze petroleum. 

All mineral lubricants of whatever grade are more or less alike 
chemically, in that they are composed of petroleum hydrocarbons. 
There are two chief requirements to which they all must conform. 
They must not be appreciably volatile, so that loss of volume and risk 
by fire may be reduced to a minimum, and they must possess a certain 
viscosity so that they can adhere to the metal surfaces which they are 
to lubricate, and maintain a film of sufficient thickness between them. 

The nature and quality of mineral lubricants vary with the purpose 
to which they are applied. The principal grades in common use are 
the following ; the flashing points given are all by the closed test : — 

1. Spindle Oils, especially adapted to spinning machinery, pale 
mobile oils of flashing point i6o°-200°. 

2. Compressor Oils {^Freezing Machinery Oils). — Thin oils of solidify- 
ing point below —20°; flashing point 140°- 180". 

3. Lubricating Oils for Light Machinery. — (Oil for shafting, light 
motors, turbines, and dynamos.) Moderately thick oils of flashing 
point i7o''-220^ Gas-engine oils should flash at i95°-220°. 

4. Lubricating Oils for Lleavy Work. — Thick oils of flashing point 
1 90° -2 20". 

The above-mentioned varieties are generally refined oils ; they arc 
of a clear yellowish- or reddish-brown colour; certain high-class oils of 
groups I, 2, and 3 are nearly colourless ; compressor oils are sometimes 

^ The Editor is indebted to Mr J. S. S. Brame, Lecturer on "Fuel," The Sir John Cass 
Technical Institute, for very kindly reading the proofs of this section, the manuscript of which 
had been revised by the late Dr. Lewkowitch, C.A.K. 



58 



CLASSIFICATION OF LUBRICANTS 59 

artificially coloured to a violet tint. The cheaper kinds of heavy 
machinery oil are opaque. 

5. Heavy Railway Waggon and Engine Oils. — " Summer oil," flash- 
ing point above 140°, solidifying point below —5°. "Winter Oil," 
solidifying point below —20°. 

6. Cylinder Oils represent the highest boiling fractions of petroleum. 
They are mainly the still residues of the lubricating oil fractions of 
heavy consistency; they congeal to vaseline-like masses at ordinary 
temperatures or a few degrees above 0°. Those oils, which have 
been filtered over fuller's earth, are brownish-red and translucent ; 
undistilled and unfiltered oils are greenish-black and opaque. In 
reflected light the paler American oils show a greenish-grey, the 
Russian oils a bluish fluorescence. The flashing points range from 
22o°-3i5°, the better qualities flashing not below 260°. Superheated 
oils flash at from 28o''-300°, or even higher. 

{b) Fatty Oils and Liquid Waxes. — The chief kinds employed 
as lubricants are crude and refined rape (colza), olive, castor, animal 
oils (lard, tallow, neat's foot, bone, etc.), sperm and arctic sperm oils, 
and palm oil. Even blubber oils and also wool-grease are occasionally 
used as lubricants. 

(c) Mixtures of Fatty and Mineral Oils are used frequently. For 
marine engines a mixture of blown rape oil and a mineral oil sold as 
" marine oil " is largely employed. Mineral cylinder oils often receive 
an admixture (2-12 per cent.) of bone fat. 

(cf) Lubricating Greases are employed to some extent on account 
of their easy and, in certain cases, economical application. They 
consist of solutions of lime-soaps or lime-alkali-soaps in mineral oils, 
and contain, as a rule, from 2-6 per cent, of water ; they usually liquefy 
at 70° or 80°. Other lubricating greases are mixtures of wool-grease, 
tallow, alkali-soaps, etc., with mineral oil. Lubricants containing 
graphite are employed as lubricants for cog-wheels, bicycle chains, and 
the like. This class of lubricants is likely to be replaced in the near 
future by the Acheson Graphite Company's compounds ("Oildag," 
" Aquadag ").^ The lowest class of lubricating greases is represented 
by the axle and waggon greases ; these contain lime-soaps, rosin oil, 
lignite-tar or coal-tar oils, also magnesium silicates such as talcum. 
The cheapest products are adulterated with barytes, plaster of Paris, etc. 

(e) Water-Soluble Oils have the property of yielding homogeneous 
emulsions with water, and are prepared by dissolving ammonia- or 
alkali-soaps in pale mineral oils (sometimes with the addition of 
petroleum naphtha). They are chiefly used for lubricating tool- 
machines, for charging hydraulic presses and conduits, for oiling yarn 
in the textile industries, and as dust-laying oils. 

^ Cf. Archbutt and Deeley, Lubrication and Lubricants^ 3rd ed., 1912, pp. 150 et seq. 



60 LUBRICANTS 

(/) Thickened Oils. — For some purposes mineral oils are thickened 
by dissolving in them small amounts of unvulcanised rubber or of 
aluminium sulphate. 

{g) Non-Oleaginous Lubricants. — There are a few exceptional 
cases in which oily lubricants would be dissolved or chemically attacked, 
and are therefore inapplicable. In chlorine and oxygen compression 
plants, for example, strong sulphuric acid and dilute glycerine respec- 
tively are the lubricants used. In the sulphur dioxide industry the 
liquid sulphurous acid itself acts as a lubricant for the pistons and 
c)-linders. 

^.—MINERAL OILS. 
Physical Tests. 

I. APPEARANCE. 

A practised observer can derive valuable information from the 
colour, transparency, smell, and consistency of a lubricating oil. The 
odour of an oil is best observed by rubbing a drop or two in the palm 
of the hand. 

(a) Colour. — The colour of an oil is conveniently noted in a thickness 
of lo cm. In special cases the examination may be carried out either 
with Lovibond's tintometer,^ or with Stammer's colorimeter (see the 
section on " Mineral Oils," p. 23). 

Colour varies, according to the degree of purification, from water- 
white to dark red by transmitted light. Pale oils (not treated with 
nitronaphthalene or aniline dyes to render them non-fluorescent) 
invariably show a fluorescence, which is green in the case of American 
oils and bluish in the case of Russian oils. 

Fluorescence is best ascertained by observing a drop of oil upon 
glazed black paper; fluorescent oils appear blue, whilst treated oils 
appear simply black. For the detection of deblooming substances 
such as nitronaphthalene, etc., see p. 94. 

Oils containing still residues in notable quantity and not filtered 
over fuller's earth are opaque and very dark. Machinery oils are 
almost without exception transparent. 

Unfiltered cylinder oils have an opaque greenish- or brownish-black 
appearance. If filtered or mixed with filtered residues they are dark 
red and translucent. Solid, readily melting particles separating in thin 
layers from the oil are, as a rule, paraffin wax, pitch, or ozokerite ; 
the latter material is added as a thickening agent to certain Russian 
cylinder oils. 

A slight turbidity in pale oils is frequently due to suspended water. 

' Cf./. Soc. Chem. hid., 1888, 7, 424 ; 1890, 9, 10 ; 1894, 13, 308. 



MINERAL OILS. SPECIFIC GRAVITY 61 

(b) Consistency. — Cylinder oils are liable, owing to changes of 
temperature and agitation immediately before examination, to present 
very puzzling indications. It is best to pour such oils into a test 
tube 15 mm. in diameter and 3 cm. high, warm for ten minutes in the 
water-bath, and allow to cool for one hour in water at 20°. The con- 
sistency is then observed on inclining the test tube. 

(c) Mechanical Impurities are easily recognised in pale oils. Dark 
oils must be passed through a sieve of ^ mm. mesh ; not less than 
250 c.c. should be poured through the sieve. 

II. SPECIFIC GRAVITY. 

The specific gravity of mineral lubricating oils is of importance 
only when oils of known definite origin are to be compared, or as 
a means of identification, although it is usual in commerce to sell the 
oil with a statement as to the specific gravity. 

Determination of the Specific Gravity by Means of the 

Hydrometer. 

(a) Standard Hydrometer — The specific gravity of mineral 
oils (and liquid fats or waxes) may, if sufficient material is available, be 
determined by means of a reliable hydrometer. 

In Germany officially calibrated hydrometers, standardised for 
+ 15° C, water at +48° being the basis, are obtainable ; Tables specially 
adapted to American petroleum and its products have been prepared by 
the Normal-Eichungs-Kommission of Germany.^ The temperature of 
the experiment is determined by a thermometer attached to the 
hydrometer spindle. 

Hydrometer readings are, whenever possible, taken at the flat level 
of the liquid, viewed from below ; but when the oil is too dark, it 
is necessary to read at the upper edge of the meniscus and to add 
0001 5 or o-ooio, according to the dimensions of the scale, to the specific 
gravity found. Care must be taken that the hydrometer floats freely in 
the liquid ; the reading should not be taken before fifteen minutes 
have elapsed after the immersion of the hydrometer. 

The specific gravity is corrected to the standard temperature of 15°, 
For each degree difference between the observed and standard tempera- 
ture a correction of ± -00068 is made. 



Exainple. 




Hydrometer reading at i7°-5 . 


0-9010 


Meniscus correction . 


4-0-OOIO 


Temperature correction, 2-5 x -00068 . 


+0-0017 


Specific gravity at 15 


0-9037 



^ Published by J. Springer, Berlin. 



62 



LUBRICANTS 



The following Table, worked out by Mendelejefir, gives the tempera- 
ture corrections for high-boiling Russian petroleum oils: — 

Table 15. 



Sp. gr. of fraction. 


Correction per 1°. 


0-860 to 0-865 


0-000700 


0-865 „ 0-870 


0-000692 


0-870 „ 0-875 


0-000685 


0-875 „ 0-880 


0-000677 


0-880 „ 0-885 


0-000670 


0-885 „ 0-890 


0-000660 


0-890 „ 0-895 


0-000650 


0-895 „ 0-900 


0-000640 


0-900 „ 0-905 


0-000630 


0-905 „ 0-910 


0-000620 


0-910 „ 0-920 


0-000600 




(6) Determination of the Specific Gravity by Pyknometers. — 

ii great accuracy is required, or if 
there is not enough oil available to 
use a hydrometer, a pyknometer, such 
as the ordinary Sprengel tube or a 
Mohr's balance, is employed for the 
determination of the specific gravity. 
A serviceable form of pyknometer 
devised by Gockel for highly viscous 
oils is shown in Fig. 15; it has a 
capacity of 10 c.c. at 15° and is fitted 
with a ground-in thermometer. If 
the calibration is correct, the absolute 
weight of the sample divided by 10 
gives the specific gravity at 15° with- 
out further calculation. Correction to 
standard temperature and water at 
4° is made by the aid of the data 
given above. 
If only a few cubic centimetres of the sample are available, a small 
pyknometer is used. 

In order to determine the specific gravity of pitch-like lubricants 
heavier than water, the pyknometer is employed as follows. A 
small quantity of the substance, melted if necessary, is poured on the 
bottom of the vessel and allowed to cool ; the pyknometer is then 
weighed, filled up with water, and again weighed. 

(c) Determination of the Specific Gravity by the Flotation 
Method. — The specific gravity of very small quantities of a lubricant 



Fig. 15. 



MINERAL OILS. EXPANSIBILITY 



63 



may be determined, provided the substance is insoluble in dilute alcohol, 
by floating it in dilute alcohol of identical density. 

Table i6. 
Specific Gravity of various Oils at 15°. 





American. 


Russian. 


Lamp oil . 

Spindle oil . . . 
Machinery oil . 
Cylinder oil . 


0-780 to 0-800 
0-840 „ 0-907 
0-875 „ 0-914 
0-883 ,, 0-895 


0-800 to 0-830 
0-850 „ 0-900 
0-900 „ 0-915 
0-909 „ 0-932 
(exceptionally up to 0-950) 


Heavy rosin oil . 

Coal-tar oil .... 
Lignite-tar oil .... 


0-973 to 0-982 

(exceptionally up to 1-000) 

1-090 to 1-100 

0-893 „ 0-974 



Preliminary trials are made by dropping a little of the oil or melted 
fat into a series of mixtures of alcohol and water of progressive densities, 
in order to ascertain approximately the upper and lower limits. The 
liquid nearest to the substance in specific gravity is then adjusted, by 
adding very dilute, or as the case may be, absolute alcohol, a thermometer 
being used as a stirring-rod, until the substance just floats in the liquid 
without either rising or sinking. The specific gravity of the liquid is 
then determined accurately ; it equals the specific gravity of the sample 
at the temperature of experiment. It is essential that no air-bubbles 
adhere to the floating globules of oil. 

in. EXPANSIBILITY. 

Although coefficients of expansion do not find a place among the 
commonly accepted characteristic constants of oils, they are required for 
calculating specific gravities to different temperatures, and especially for 
calculating the expansion-space to be allowed for transport, and in 
storage vessels. 

The expansibility is determined either by taking the specific 
gravity at successive temperatures (for corrections for temperature, see 
p. 65) or by a dilatometric method. For the latter purpose an apparatus 
which allows of the simultaneous examination of eight samples has 
been devised by Holde (Figs. 16-18). The dilatometers (Fig. 16) have 
the shape of bulbs of about 30 c.c. capacity, with graduated stems 
07 mm. in bore, holding about 850 cb.mm. The initial volume of 
oil at ordinary temperatures is adjusted in a large water-bath arranged 
like a calorimeter as shown. For higher temperatures the water-bath 
B is placed in a vapour-bath A (Fig. 17) heated by a Bunsen burner. 



64 



LUBRICANTS 



The vapourising liquid, which is chosen according to the temperature 
required, may be ethyl ether (boiling point 35''), ethyl bromide (boiling 
point 38'), chloroform (boiling point 61''), carbon bisulphide, alcohol, 
or any other suitable liquid. Reflux condensation is provided for at e. 
A number of dilatometers, together with a thermometer graduated to 
tenths of a degree, are suspended by means of rubber rings in the 
water-bath. Fig. 18 illustrates the method of charging the dilato- 
meters with oil by suction with a copper or brass capillary tube ; 
discharging is performed similarly by blowing in air. Air-bubbles 
remaining at the junction of the bulb and stem can usually be 
removed by judicious use of the suction-capillary. Any oil adhering 




-^#=2 





Fig. 16. 



Fig. 17. 



Fio. 18. 



to the upper part of the stem is wiped away by means of a spiral wire 
wound with cotton wool. 

The stems of the dilatometers are carefully calibrated, once for all, 
with the aid of mercury. To empty the mercury for the purpose of 
weighing, a thread of glass, which is weighed with the receiving beaker, 
is pushed up the stem. The volume of the dilatometer up to the zero 
mark is determined by weighing it filled with water ; in this case the 
weighings must be reduced to vacuum, which is unnecessary in the case 
of the mercury thread calibration. 

The coefficient of expansion a is calculated by the following 
formula : — 

V,-V 



a 



(^-/)V 



+<? 



MINERAL OILS. VISCOSITY 65 

where V is the initial volume at temperature /, V^, the greater volume 
at the higher temperature t^, and c the cubic expansibility of glass, which 
may be taken as 0-000025, or may be ascertained by determining the 
apparent expansion of the mercury before the experiment. 

For heavy viscous machinery and axle oils of sp. gr. not less than 
0-908, the value of a between 20^ and 78° is o- 00070-0- 0007 2. Oils of 
this class from which particles of wax or pitch separate out at and below 
+ 20° show a higher value between 12° and 20"^, namely, 0-00075-0-00081. 

For light spindle and dynamo oils, of sp. gr. less than 0-905 at 15", 
the value of a is 0-0072-0-00076 between 20° and 78°. 

In the case of oils which are homogeneous liquids, the value of a 
increases slowly with the rise of temperature. 

When an oil contains fusible matter in suspension, a decreases with 
rising temperature up to the point when all the suspended particles are 
liquefied, and then increases as in the case of a homogeneous liquid. 

In the case of oils of different origin but of equal viscosity, a 
difference in expansibility corresponds to a difference in chemical 
composition. 

According to Singer,! Roumanian petroleum residues have an 
expansibility of 0-00073-0-00079. 

Specific Gravity Correction. — In recalculating the specific gravity 
from a higher to a lower temperature, or vice versa, the allowance per 
1° for liquid mineral lubricants is 0-00063-00072, or 0-00065 as a mean 
value. 

When specific gravities are determined by the pyknometer at 
temperatures above 30°, allowance must, in addition, be made for the 
expansion of the pyknometer itself. 

In the case of vaseline-like lubricants or of very viscous cylinder oils, 
for which a ranges from 0-000777-0-000876,^ a mean correction of 0-00075 
per i'' may be taken. 

IV. VISCOSITY. 

The accurate determination of the internal friction of liquids 
requires the use of apparatus which is unsuited for technical work. 
For practical purposes more simple apparatus is employed, by means of 
which a relative determination of viscosity is effected. The determina- 
tion is usually made by ascertaining the times occupied by two equal 
volumes of the liquids under comparison to flow through a narrow 
aperture under exactly the same conditions. The numbers thus 
obtained are entirely arbitrary, and are different with the various forms 
of apparatus, viscometers, employed for the purpo.se. 

The viscosity of oils is, in practice, generally compared with that of 

^ C/iem. Rev.^ 1896, 13, 298. ^ Miiteilungen, 1895, Ergiinzungsheft, v., p. 23. 

Ill E 



66 LUBRICANTS 

rape oil. Boverton Redwood^ found from a number of tests carried out 
with refined rape oil in his viscometer that the average time occupied 
by the outflow of 50 c.c. at 60^ F. (i5'-5 C.) is 535 seconds. Taking this 
as a standard and its viscosity as = lOO, the viscosity of any other 
oil is found by multiplying the number of seconds occupied by the out- 
flow of 50 c.c. by 100 and dividing by 535. If the specific gravity of the 
oil differs from that of rape oil, which is 0-915 at 60' F., Redwood 
introduces a correction by multiplying the above result by the specific 
gravity of the sample and dividing by 915. 

The viscosity of an oil, V, is therefore obtained from the equation : — 

■y _ nx 100 X J- 
535x915 

where n is the time of outflow and s the specific gravity of the oil under 
examination. 

As there is no correlation between the specific gravity and viscosity 
of an oil, it is more useful to record the numbers as obtained by the 
direct determination of the viscosity, and to omit the specific gravity 
correction (Lewkowitsch). 

Of the many forms of viscometer that have been designed, those of 
Redwood, of Saybolt, and of Engler are the most important. Redwood's 
apparatus is the recognised standard instrument in this country, and 
has been adopted by the Government, by the principal Railway 
Companies, and by the Scottish Mineral Oil Association. Saybolt's 
viscometer is used in the United States, and that of Engler in Germany, 
and generally on the Continent. In France an instrument known as an 
" Ixometre," designed by Barbeys, is employed. 

Boverton Redwood's Viscometer.- — This instrument, which is 
shown in Fig. 19 and in section in Fig. 20, consists of a silvered copper 
oil-cylinder C, about i| in. diameter and 3^ in, deep. The bottom of 
the cylinder is provided with an agate jet D, the cavity of which can be 
closed by means of the plug E formed of a small silvered brass sphere 
attached to a wire. A small bracket F terminating in a point is fixed 
at a short distance from the top of the inside of the oil cup, and serves 
as a gauge of the height to which the oil must be filled. The ther- 
mometer T is immersed in the oil. The oil-cylinder is surrounded by 
a copper jacket J, provided with a closed side-tube K, which serves for 
heating the contained liquid to the desired temperature ; a revolving 
agitator L, worked by the handle II, is provided together with a ther- 
mometer T^ for recording the temperature of the liquid in the jacket. 
The whole instrument is supported on a tripod stand furnished with 
levelling screws. 

' /. Soc. CItem. Ind., 1886, 5, 126. » /^/^^ 



THE REDWOOD VISCOMETER 



67 



To carry out a determination, the copper jacket is filled with water 
for temperatures up to 95°, and for higher temperatures with a suitable 
mineral oil, up to a height corresponding roughly with the pointer F in 
the cylinder C. After the liquid in the jacket has become heated to 
the required temperature, the oil to be tested, previously purified and 
dried and heated to the same temperature, is poured into C until its 
level just coincides with the point of the gauge ; great care must be 






e %^ 



Fig. 19. 



Fig. 20. 



taken that this level is reached exactly, and that the temperature remains 
constant during the observation. A narrow-necked flask holding 50 c.c. 
to a point marked on the neck is then placed below the jet D in a 
vessel containing a liquid of the same temperature as the oil. The plug 
E is then raised, and the number of seconds required for 50 c.c. of the 
oil to flow out is carefully observed by means of a chronometer. 

At least two tests should be made at the same temperature ; if due 
care has been taken the two observations should be closely concordant. 
The viscosity value is then calculated to the standard of rape oil as 
described above. 



68 



LUBRICANTS 



Saybolt's Viscometer. — The jet of this viscometer is made of metal, 
and is eiiclused in a tube which extends below the orifice. The oil- 
vessel is contracted above the jet, and is cut away longitudinally on each 
side to expose a glass tube with which it is lined, and which can be seen 
by means of glass windows provided in the water-bath in which the oil- 
vessel is placed. The upper level of the oil is regulated by means of an 
overflow gallery, the position of which determines the length of the oil 
column, and the outflow, which is observed through the windows of the 
bath, is stopped w^hen the oil reaches a certain point in the inner glass 
tube of the oil vessel.^ 

C. Engler's Viscometer. — The vessel A (Fig. 21), which serves for 
the reception of the oil to be tested, is filled with oil up to the tip of 




Fio. 21. 

a small pointer fixed to the side of the vessel, whilst the efflux tube, 
which is either made of or lined with platinum, is closed by a wooden 
rod b which passes through the cover c. The oil (or water) is caught 
as it flows out in the measuring flask which is graduated at 200 
and 240 c.c. When the measuring vessel has three bulbs as in 
Fig. 21, and has a graduation mark at 100 as well as at 200, each 
experiment can be controlled in itself by reading the time of outflow 
from 100-200 c.c. 

In order to heat the oil to the required temperature for the test, the 
inner vessel is surrounded by a heating jacket B, which is filled either 

' For further details see Redwood, Petroleum and its Products, 3rd ed., 191 3, vol. 
ii., p. 279. 



VISCOSITY OF MIXTURES 69 

with water or with a high-boiling mineral oil ; the heating is effected 
by a movable ring-burner at least lo cm. in diameter, and the bath 
stirred by the stirrer DE, thus avoiding any superheating of- the outlet 
hole ; F is a small catch which supports the plunger and prevents it 
from slipping into the orifice during the experiment. 

The expression for the viscosity, generally called " Engler degrees," 
is the quotient obtained by dividing the time of flow for 200 c.c. of 
the oil at any specified temperature, by the time of flow of 200 c.c. of 
distilled water at 20°. 

The relative value of viscosity determinations by Redwood's and 
by Engler's apparatus has been investigated by W. F. Higgins.^ 
Calculated from theoretical considerations, the ratio of the readings 
is approximately constant for times of flow on the Redwood viscometer 
greater than 100 seconds and is = i-8i (Engler : Redwood) ; below 
this the ratio increases with decrease in the time of flow from 1-82- 1-83. 
Experimental results on three different oils and at temperatures vary- 
ing between 10° and 45° gave ratios between 1-74 and 1-84. 

Viscosity of Mixtures of Oils. 

As the viscosity is not an additive property, the viscosity of 
mixtures cannot be calculated directly from the proportions of the 
components, but is always lower than the calculated value. According 
to experiments by H. Sherman, T. Gray, and H. Hammerschlag,^ if the 
viscosities are plotted as ordinates and the percentages of ■ the 
components as abscissae on squared paper, the relationship between 
the two is expressed by hyperbolic curves which deviate more strongly 
from the straight lines joining the extreme points, the more the 
viscosities differ from one another. Mixtures of different mineral oils 
give greater deviations from the straight lines than mixtures of mineral 
with fatty oils. 

For the determination of the viscosity of the unsaponifiable portion 
of a blended oil, the viscometers described above will, as a rule, be found 
to be too large. In such cases Kiinkler's viscometer, which requires 
only 30 c.c. of the sample, will be found useful.'' 

Absolute Viscosity. 

The desirability of expressing viscosities in absolute measure, 
instead of by the arbitrary values at present adopted, has recently 
received consideration. The absolute viscosities of water and of 

1 J. Soc. Chem. Itid., 1 91 3, 32, 568. 

2 J. Ind. Eng. Chem., 1909, 1, \2 \ J. Soc. Chem. Ind., 1909, 28, 17. 

^ Dingl. Polyl. /., 1893, 290, 2S1. Cf. also Lewkowitsch, Chemical Technology and Analysis of 
Oils^ Fats, and Waxes, vol. iii. , p. 52. 



70 



LUBRICANTS 



glycerol have been determined by L. Archbutt and R. Deeley,^ and 
a series of determinations of the absolute viscosities of a number of 
mineral oils in C.G.S. units has been carried out by W. F. Higgins- 
at the National Physical Laboratory in connection with his work 
for the International Commission for the unification of tests on 
petroleum products. 



n^ 



V. BEHAVIOUR OF OILS AT LOW TEMPERATURES. 

In order to judge accurately of the consi.stency of oils when exposed 
to cold, the following points must be taken into account. 

When mineral oils, in passing from the fluid to the semi-solid 
condition, are disturbed, the network of separated solid matter is 
ruptured, and the "crystallising" process is greatly affected. In ex- 
amining oils at low temperatures, therefore, cooling must take place 
without agitation. 

Oils must be cooled during at least one hour to the desired 
temperature, since the solid particles separate with great reluctance, 
_ and temperature equilibrium is attained very slowly. If an 
oil has been heated before being cooled down, its physical 
condition is altered to such an extent as to modify the 
freezing point considerably. In the same way, the effect 
of alternate cooling and warming to room-temperature is to 
render the freezing point hopelessly variable. Oils may be 
exposed to fluctuations of temperature during transportation 
or storage, and this possibility must be taken into account 
when they are tested. 

Pale heavy mineral oils are sometimes known to set to a 
jelly whilst remaining perfectly transparent. 

The question to be decided is whether, and to what 
extent, an oil is fluid at a certain temperature, say — s" 
or —15"; or, alternative!)-, at what temperature solids 
separate out and the oil becomes semi-solid. Much time 
is saved by making a preliminary test with the apparatus 
shown in Fig. 22 : the oil is cooled down in a test tube 
by means of a mixture of ice and salt, and its behaviour on tilting 
the test tube is observed from time to time. The approximate solidi- 
fying point being now known, a series of refrigerating solutions which 
can be kept at a constant freezing point for an hour or more is pre- 
pared, according to the subjoined data. These solutions are partially 
frozen by means of a mixture of one part of salt and two parts of 
pounded ice or snow. 

' Lubrication and Lubricants, pp. 153 ^/ seq. 
2/. Soc. Client. Ind., 1913, 32, 568. 



I 



FlO. 22. 



BEHAVIOUR AT LOW TEMPERATURES 



71 



Temperature. 

o 

o 

- 4° . 



- 5° . 

- 8°7. 
-io° . 

-14° • 

- 15° to 



15-4 



Solute. 


Parts to 100 of water 


Ice 


• • • 


KNO3 


13 


fKNOa 

iNaCl 


1'^ 


I 2 


/KNO3 
iNaCl 


\ 3-3 


BaCl., 


35-8 


KCl 


22-5 


NH^Cl 


20 


NH4CI 


25 



For most practical purposes it is sufficient to ascertain whether an 
oil flows or does not flow at the temperature of experiment. The 
apparatus shown in Fig. 23 may be used with advantage for this 




Fio. 23. 

purpose.^ A vessel of enamelled iron a, about 12 cm. wide, holds the 
standard solution, and is surrounded with a freezing mixture d con- 
tained in the earthenware pan c, which is lagged with felt. Test tubes 
filled up to a mark (3 cm. high) with oil are placed in the holder 
attached to a. After the samples have been cooled for one hour they 
are examined as in the preliminary test. A further differentiation as 
to consistence may be made by placing glass rods in the test tubes 
for a quarter of an hour, and noting whether the tubes are moved up 
bodily when the rods are lifted. If the standard refrigerating solution 
shows any tendency to fall below the proper temperature, the ice which 
has deposited round the inner sides of the vessel is knocked away 
and the outer freezing mixture is removed. Temperatures are read 
by means of a thermometer graduated to tenths of a degree. The 
freezing mixture may have to be renewed from time to time, but as a 
rule this is not required, except at the lowest working temperatures. 

^ C/. Hofmeister, Mitteilmjgen^ 1889, p. 24. 



72 



LUBRICANTS 



Constant temperatures of —20" to —21° may be maintained by 
filling both the inner and outer vessels with the freezing mixture of 
ice and salt. To obtain still lower temperatures a thin metal inner 
vessel (not enamelled) is used, and both this and the outer vessel are 
charged with alcohol into which solid carbon dioxide is thrown as 
required. 

Quantitative Comparison of Fluidities. The Freezing 

Point or Cold Test. 
A quantitative statement as to the behaviour at low temperatures is 
sometimes required for the valuation of dark railway oils, and ma)- be 
obtained by the aid of the apparatus shown in Figs. 24, 25, and 26. 




Fio. 24. 



Fio. 25 



20 
10 



S 



This determination is not so important in this country as in the United 
States and on the Continent, where the danger exists of machinery 
being damaged by the oil becoming solid in the lubricators. Fig. 24 
is a diagrammatic representation of the apparatus prescribed for the 
testing of oils by the Prussian State Railways ; Fig. 26 shows the 
actual form of the apparatus. To carry out the test the oil is thoroughly 
shaken in the sample bottle, and freed from mechanical impurities by 
filtration through a sieve of ^ mm. mesh. In order to take the effect of 
previous heating into account, four tests are made, two with untreated 
oil, and two with oil which has been heated on the water-bath to 50" for 
ten minutes. In all cases, as also when the simple test described in the 
preceding paragraph is carried out, it is well to conduct the preliminary 
heating and cooling in the actual testing vessel, be it a test tube or a 
U-tube. 



FLUIDITY TEST 



73 



The oil is charged by means of small pipettes fitted with a rubber 
ball into the longer limb of the testing vessel. This latter consists of 
a U-tube (Fig. 25) of 6 mm. bore, having a millimetre graduation as 
illustrated. It is important that these tubes should have no constric- 
tion at the bend ; at no point should the bore exceed or fall short of 
6 mm. by more than 0-3 mm. The level of the oil is adjusted to stand 
at the zero mark, which is 3 cm. above the bottom of the U-tube. The 
tube is immersed in a vessel h (Fig. 24 in which two tubes are shown) 
filled with the freezing mixture of the specified temperature, and 




Flo. 26. 



surrounded by the vessel /, which is also filled with the freezing 
mixture ; the temperature is controlled by the thermometer /. The 
U-tube should stand for at least one hour in the freezing mixture without 
being disturbed, the level of the oil being about 10 mm. below that of 
the freezing mixture. The tube is then carefully drawn out so far that 
the level can be observed, when the rubber tube d is slipped over its 
end whilst the pinch-cock e is open. This pinch-cock is then closed and 
the pinch-cock f opened, whereby a pressure of 50 mm. is allowed to 
act on the oil ; this pressure is generated by pouring water into the 
vessel a, in which a weighted funnel b is placed, and controlled exactly 
by the manometer c. The height to which the sample of oil has risen 
when compressed is read off on the shorter limb of the U-tube, the oil 



74 LUBRICANTS 

adhering to the sides showing the required level even though the body 
of oil may have sunk a little ; this height expresses quantitatively the 
fluidity of the sample under compression. 

The Scottish Mineral Oil Association directs that the setting point 
of mineral oils be determined in the following manner:^ — Place the 
sample in a test tube, having a diameter of ij in., to the depth of 
about 2 inches. Immerse the test tube in a freezing mixture and 
stir the oil slowly with a thermometer until it has cooled down con- 
siderably below the temperature at which solid paraffin wax first 
appears. Then remove the test tube from the freezing mixture, stir 
constantly with the thermometer, and observe the temperature at which 
the last trace of solid paraffin wax disappears. The temperature thus 
found is the setting point. 

VI. VOLATILITY AND INFLAMMABILITY, 

Within certain limits, volatility runs parallel with the flashing point, 
which latter is readily determined either by the "open" or "closed" 
test. Thus the quality of machinery and cj-linder oils may, so far as 
volatility is concerned, be judged by their flashing points. 

Flashing points, however, are not reliable criteria of volatility unless 
they lie above the minimum admissible limit, i.e., unless lower petroleum 
fractions are absent. To decide this point it may be necessary to 
undertake a fractionation of the oil, or to determine the loss in weight 
on heating in an open vessel. The fixing of minimum flashing points 
for the various sorts of lubricating oils is a great desideratum. When 
lower fractions are absent, the distillation test is useless and even mis- 
leading. In practice almost the only lubricants which are tested for 
volatility are cylinder, superheated, and turbine oils, also transformer 
oils (see preceding Section, p. 43). 

Volatility may be judged not only by the flashing point of an oil 
but also by its ignition point, i.e., the temperature at which the oil takes 
fire and burns steadily. Some authorities hold that this is an even 
better criterion of volatility than the flashing point. 

(a) Evaporation or Volatility Test. 

The volatility of a mineral lubricating oil is ascertained by determin- 
ing the loss in weight it undergoes at a given temperature. Several 
special forms of apparatus have been constructed for this purpose. 

I. L. Archbutt's Vaporimeter.- — This consists of a straight copper 
tube 1-2 ft. in length, having a branch tube attached at one end 
and coiled round it as shown in Fig. 27. The tube and coil are placed 

1 /. Soc. C/iem. hid., 1891, 10, 347. - Ibid., 1896, 15, 326. 



THE ARCHBUTT VOLATILITY TEST 



75 



in an air-oven provided with a thermometer; the ends of the tube are 
closed by brass screw-caps, one of which is provided with an exit- 
tube. The sample of oil is placed in a platinum boat which is placed 
in a glass carrier. The current of air in which the drying is effected is 
first heated to the required temperature in the coil before entering the 
actual drying tube, whereby a constant temperature is ensured ; it is 
maintained at a constant speed by means of a suitable regulator. 

The sample is exposed to the current of air for exactly one hour ; 
0-5 g. of oil is taken for each determination, and the temperature of the 
oven is varied to suit the requirements of the test. For cylinders 
working at 150 lbs. pressure per square inch, the oil is tested at 370" F. 




CcpperpifjA Oil tray Clasaiuhe 




Fio. 27. 

(188° C), and should not lose more than o-5-i-o per cent, in weight. At 
400° F. ( = 235 lbs. pressure) the loss of weight of cylinder oils is about 
two and a half times as great as at 370° F. 

A flashing point apparatus in use in the United States, known as 
the New York State Board of Health Tester, is so fitted as to allow of 
the determination of the evaporation loss as well as of the flashing 
point. The outer bath of the tester is charged with water, whilst a 
known weight of the oil under examination is placed in the usual 
container. By keeping the water boiling, the oil is maintained at 
208^-210° F. (about 98^-5 C.) during five hours, whereupon it is rapidly 
cooled to about 10° F. (5°-5 C.) and again weighed. Under these con- 
ditions a good machinery oil ought not to lose more than o-i per cent. 
The apparatus is apparently not intended for determining evaporation 
losses at higher temperatures. 



76 



LUBRICANTS 



2. F. Schreiber's Apparatus.' — This is a modification of the 
apparatus desii^ned b\' Iluldu for the determination of the volatility, the 
object of which is to obtain indications of the actual efficiency of a 
lubricant under working conditions. 

The oil to be tested is spread out in a thin layer and is uniformly 
heated from all sides, as in the cylinder of the steam engine. 

The oven (Fig. 28) consists of a heating jacket in which high-boiling 
compressor oil is heated by a Bunsen burner. If the gas pressure is 
constant, the variations of temperature do not exceed ± 2 . The oils 
are placed in shallow glass dishes of So-85 mm. diameter and 20 mm. 
deep, which are placed on a perforated shelf in the middle of the oven. 
The top of the oven has six openings to allow the vapour to escape, or 
to allow steam or gases to be passed through the oven in case it is not 
desired to carry out the test in air. 10 g. of the oil are weighed out 
into each of the dishes and heated for ten to twenty-four hours at 200^ 
The loss of weight by evaporation, and the increase of the amount of 
substances insoluble in benzine and benzene are ascertained. It has 
been found that in the case of oils which have not proved efficient under 
practical conditions, both of these amounts are high (Oils I. and II. in 
Table 17). Specific gravity, viscosity, and flashing point do not always 
give reliable indications of the volatility, as is shown by a comparison 
of the samples II. and V. in the subjoined Table, which have the same 
flashing point and specific gravity, but which gave very different losses 
on heating, viz., 878 per cent, in the case of II. and only 1-35 per cent, 
in the case of V. The results obtained in the case of five mineral oils 
are shown in Table 17 ; of these the two first proved unsatisfactory 



under working conditions. 



Table 17. 



Oil number. 



Specific gravity 

,,. ., fat 100° 
Viscosity 1^^ J5Q. ^ _ 

Flashing point "\ in open/ 

Burning temperature J vessel \^ 
Per cent, of T Insoluble in benzine 
asphallic -! InsoIul:ile in ether- 
substances y alcohol 

Loss on evaporation after 16 hours, 
per cent. . . • . . 

Asphallic substances after healing, 
insoluble in benzine, per cent. . 

Insoluble in hot benzene after 
heating 

Other characteristics 



0-904 

2 '65 
317° 
362= 

0-16 

1-07 
13-6 



II. 



0-905 

2-30 
331° 
372° 

0-04 

0-54 
8-78 



at 250 



- 10-8 

mostly 

insoluble 

oil was solid 

and resembled 

parchment 



•13 



4-04 

oil was a 
tough doughy 



mass 



in. 


IV. 


0-906 


0-916 


6-24 


6-32 


2-34 


2-34 


338° 


319° 


382° 


374° 


0-05 


0-64 


1-59 


1-65 


1-15 


3-66 



0-908 
7-00 
2-51 
332° 
378° 
0-05 

2-29 

1-35 



at '280' 
1-26 1-84 1-28 



1-02 1-46 



0-98 



liquid, without 
appieciable change 



1 Z. angew. C/iem.^ 1910, 23, 99 ; /. Soc. Chcm. Ind., 1 910, 29, 202 




Fig. 28. 



I To Jace page 76. 



THE FLASHING POINT 



77 



The great increase of asphaltic substances is due to oxidation, as 
was proved by the influence of steam and gases on the evaporation and 
character of the oil. A certain amount of formation of asphaltic 
compounds occurred even on heating in steam or carbon dioxide, but 
this may be ascribed to the presence of small quantities of oxygen ; 
at any rate it was much less than when the oil was heated in air. A 
mineral oil containing 0-07 per cent, "insoluble" in benzine gave the 
results shown in Table 18. 



Table 18. 



Results of evaporation. 


In a current of 
air. 


In a current of 
carbon dioxide. 


In a current of 
steam. 


Quantity evaporated in 24 hours at 280° . 
Insoluble in benzine, per cent. . 
Insoluble in hot benzene, per cent. 

Other characteristics 


19-15 
15-10 
13-53 

the oil formed 
a solid parch- 
ment-like mass 


5-30 
0-99 
0-23 


15-31 

0-16 

completely 

so uble 


V 

the oil was liquid without 
appreciable change 



(b) The Flashing Point. 

The "Open" Test. — In the ordinary method of conducting this test 
the oil is simply heated up in an open crucible, in which a thermometer 
is placed, in a flat sand-bath and the temperature observed at which an 
inflammable vapour is given off. Owing to its simplicity this test is 
still largely accepted for railways, etc., and is in common use in factories 
for purposes of works control, and in trade generally. 

A modification of this test proposed by J. Marcusson consists 
in applying the mechanical arrangement used in the Abel apparatus 
(see section on " Mineral Oils," this Vol., p. 29) for approaching the 
flame to the surface of the heated oil. 

The Pensky-Martens Apparatus (Fig. 29). — Whereas determina- 
tions by the open test are subject to many uncertainties, and there 
is great difficulty in preventing the dissipation of vapour over the oil- 
surface, this apparatus is fitted with devices which ensure even heating, 
convenient approach of the igniting flame, and ready observation of 
the flash. A further advantage of the Pensky tester is that it gives 
results with low-flashing oils which stand in definite relation with the 
results by Abel's apparatus. As compared with the " open test," it is 
very sensitive to minute quantities of low petroleum fractions in other- 
wise high-flashing oils, the vapours of the former, which would simply 
escape in the open test, being detected by a low flashing point. 

The oil to be tested is poured up to a mark M into the container E, 
which stands 34 mm. high, and is heated by a triple burner. E rests, 



(8 



LUBRICANTS 



with an air-space interposed, in the iron bath H, which is protected 
against radiation by an asbestos-Hned brass mantle L. When the 
temperature of the oil has risen to about lOO , the hand-worked stirrer 
J is brought into operation, and is kept agitating without interruption 
until the end of the test. Fig. /; is a cross section of the cover and Fig. 
c a holder for removing the hot container. From 120 onward the 




Fio. 29. 



ignition flame Z, burning gas or colza oil, is plunged into the upper 
part of E at intervals of 2° ; later on, when the flame is seen to increase 
in size on insertion, it is applied at one-degree intervals, until flashing 
sets in. The temperature read on the thermometer T may be corrected 
for the errors of the instrument itself, and for the column of mercury 
protruding above the heated region. Not infrequently the flash extin- 
guishes the ignition flame. On immediately again introducing the 
flame, the same flashing point need not necessarily be observed, since 



THE PENSKY-MARTEN'S APPARATUS 



79 



further heating may be requisite to collect a sufficiency of inflammable 
vapour. 

The heating should be so controlled that, with continual agitation, 
the temperature rises 6'-iO° per minute up to 120' , and only 4°-6° per 
minute from about 20" below the flashing point. 

It rarely happens that the flashing point of a lubricating oil falls 
below 120°, but when this is the case, stirring should be begun at 80°, 
and the insertion of the ignition flame at 100°. In order to rekindle 
the latter when it goes out, a stationary flame S is kept burning near it. 

Repeated determinations usually agree to within o°-2'' ; the 
difference rarely amounts to 3°. Two determinations, of which the 
mean is taken, are therefore, in general, sufficient. 




Fig. 30. 

Much less concordance may be expected when the oil consists of a 
mixture of mineral oils and glycerides. 

A sample of oil which has once undergone a flashing test should not 
be used for a repetition of the same, since it has necessarily lost some of 
its most volatile constituents. 

When an oil containing water is heated in the Pensky apparatus 
the steam spasmodically generated has the effect of blowing out the 
ignition flame. If serious trouble be experienced from this cause, it 
is well to dry the oil beforehand by treatment with calcium chloride and 
filtration. There is no difficulty in distinguishing the blowing out of the 
flame by steam from that which takes place in the neighbourhood of the 
flashing point. 



80 



LUBRICANTS 



If lubricants should contain lamp oil, and hence flash too low to be 
dealt with by Pensky's apparatus, the Abel tester may be used 
(see p. 29). 

J. Gray's Apparatus.' — This apparatus is frequently used in this 
country for the determination of the flashing point of heavy mineral 
oils. A section of the cup and surrounding iron jacket is shown in 
Fig. 30, and the complete apparatus in Fig. 31. The cup rz which is 



m 








Fig. 31. 

made of brass is closed by a tightly fitting lid, through the centre 
of which passes a steel shaft carrying two sets of stirrers, one above and 
the other below the surface of the oil. A small bevelled wheel // is fixed 
on the top of the shaft and geared with the vertical wheel £■ which is 
worked by the small handle d. The lid is provided with four openings, 
one of which serves for the insertion of a thermometer, whilst the other 
three serve for the mechanism provided for the testing of the flashing 
point. 

' /. Soc. Chem. IiiJ., 1891, 10, 348. 



OPTICAL TESTS 81 

To carry out the test the cup is filled with the oil up to a mark 
inside which is ih in. from the bottom, the test-lamp lighted, and the 
flame adjusted so that it is about -|- in. high. The oil-cup is then heated, 
either by means of a Bunsen burner or on a sand-bath, the stirrers being 
rotated so that the temperature of the oil rises about 5" per minute at 
first, and then less rapidly as the flashing point of the oil is approached ; 
it is important not to work the stirrers too rapidly as otherwise oil is 
sent up the side of the vessel, whereby the ratio of the surface of oil 
exposed to the air space is increased, with the result that the 
observed flashing point may be 2° to 3° too low. The mechanism 
of the apparatus is then brought into play, whereby the stirring 
of the oil is stopped, the cover of the cup opened, and the test- 
lamp tilted into the opening over the cup. The temperature at 
which a slight explosion is produced is taken as the flashing point 
of the oil. If there is no flash the heating is continued as before 
and the test repeated. 

Differences between the Flashing- Points by the "Open" and 
"Closed" Tests. — In the "open" test vapours arising from the oil are 
soon carried away by atmospheric convection currents, whereas this 
cannot occur to any extent in the Pensky - Martens or in Gray's 
apparatus. Consequently the flashing points always come out higher 
by the latter than by the former method. With ordinary mineral 
lubricants the differences range from 5°-40^ according to the flashing 
point. 

(c) The Ignition Point. 

The ignition point or " Fire Test " is the lowest temperature 
at which the oil will continue to burn after a flame has been brought 
into contact with its surface for a few seconds. It is determined after 
the flashing point has been taken by removing the cover, continuing 
the heating, and testing with a small flame. 

VII. OPTICAL TESTS. 

Optical Activity. 

Certain crude petroleums and the fractions distilled from them 
slightly rotate the plane of polarisation. Rosin oils, on the other hand, 
exhibit considerable rotations. 

Mineral oils have specific rotatory powers ofo to +i°-2 rarely rising 
to +3°- 1. The rotation of rosin oils fluctuates between +30" and 44°. 
(Demski-Morawski records +50".) Fatty oils do not appreciably rotate 
the plane of polarised light, with the exception of sesame oil, which 
has a specific rotation of from +3°- 10 to 9", castor oil, which has a 
rotation of from +4o''-7 to +43", and some rarer oils and fats. 
Ill F 



82 LUBRICANTS 

The rotatory power is determined with the usual polarimetric 
apparatus. Strongly coloured oils are first dissolved, in known con- 
centration, in a colourless, inactive mineral oil, or in petroleum spirit or 
benzene. 

If [a] D be the specific rotation of the substance, the formula for 
calculation in the case of the original oils is : — 

^"^•^ = ltd 
and in the case of solutions: — 

r n looxa 

L«Jd = 



ly.pY.d 

where a is the angle of deviation read off on the polarimeter, / the 
length of the column of liquid, d the specific gravity of the oil or of 
the solution, and/ the percentage concentration of the latter. 

Refractivity. 

The refractive index permits of the detection of rosin oil in lubricants. 
Zeiss' rcfractometer (see section on "Oils, Fats, and Waxes," this Vol., 
p. 109), is the most serviceable instrument for the determination. 

The refractive index of high-boiling rosin oils is from i-530-i-55o; 
that of mineral lubricating oils from i-490-i-5oo; that of colza oil from 
I -472- 1 -474; and that of neat's-foot oil from 1-467- 1-470, all at 18'. 

Chemical Tests. 
viii. acidity and free alkali. 

In pale refined mineral oils there is no free acid, or at most traces 
(up to 003 per cent., calculated as SO3) may occur. Dark oils may 
contain up to 0-3 per cent., although their normal acidit)- may be 
taken to be 0-15 per cent, or less; if waste oils have been added the 
acidity may rise up to 0-5 per cent. The acidity is due either to 
resinous substances or to naphthenic acids of uncertain molecular 
weights ; the acidity is expressed either in terms of SO.} or as the "acid 
value." For lubricants the acidity is stated on the Continent in terms 
of SO.J. i.e.^ the number of grams of SO3 equivalent to the potassium 
hydroxide required for the neutralisation of the free acids in icx) g. 
of the oil. The "acid value" represents the number of milligrams of 
potassium hydroxide required for the neutralisation of i g. of the oil. 
1 per cent. SO3 is equivalent to an acid value of 14 ( = 705 per cent, 
oleic acid). 

Free sulphuric acid and free alkali due to traces of these substances 



CHEMICAL TESTS 83 

left from the refining processes are very rarely met with in lubricants ; 
they are detected and determined in the usual manner after extraction 
with hot water. The acidity of oils is determined by titrating either 
their ether-alcoholic solutions or their alcoholic extracts. 

Pale Oils. — For the estimation in this case lo c.c. of the sample are 
washed with 150 c.c. of a neutralised mixture of two parts of absolute 
alcohol and one of ether into a flask which already contains a little of 
the same mixture, i c.c. of i per cent, alcoholic solution of phenol- 
phthalein is added, and the titration is carried out with standardised 
alcoholic sodium hydroxide solution of such a strength that i c.c. 
corresponds to 0-004 S- SO3 (i.e. decinormal). 

Dark Oils. — In this case 20 c.c. of oil are well shaken, after warm- 
ing, if necessary, in a stoppered measuring cylinder with 40 c.c. of 
neutralised absolute alcohol. The liquid is allowed to settle over night, 
and 20 c.c. of the alcoholic layer are then withdrawn with a pipette, and 
titrated as described above. If the acidity exceeds 0-03 per cent., the 
alcoholic liquid is poured off and the oil shaken up once or twice with 
a fresh 40 c.c. of alcohol, and again titrated. 

The Detection of Mineral Acid is confined to sulphuric acid. 
About 100 c.c. of oil are shaken with twice the volume of hot distilled 
water in a capacious flask ; after the two layers have separated, 20-30 
c.c. of the aqueous extract are withdrawn with a pipette, filtered clear, 
and tested with a drop of methyl orange solution (03 g. per litre). 
Further portions of the aqueous extract may be tested for added glue, 
soap, salt, etc. (see p. 95). 

Mineral oils thickened with soap yield emulsions which refuse to 
separate into two layers ; these emulsions invariably show a decided 
alkaline reaction. 

In the case of mineral oils (especially those intended for com- 
pressors) which are artificially coloured with coal-tar dyes, the 
disturbing influence of the dyestuff may be obviated by proceeding in 
one of the following ways : — 

a. If the dyestuff is soluble in hydrochloric acid, a solution of the oil 
in petroleum spirit is shaken repeatedly with dilute hydrochloric acid ; 
this is then removed by thorough shaking with water. The decolorised 
solution is then titrated as above. 

6. If the dye is insoluble in acid, the oil is first treated with tin and 
hydrochloric acid, whereby the colouring matter is, as a rule, reduced to 
the leuco-base or other colourless derivative. The decolorised oil is 
then dissolved in petroleum spirit, washed free from acid, and titrated. 

y. A solution of the oil in petroleum spirit is shaken with a 
measured quantity of A^io alcoholic sodium hydroxide (containing 
about 50 per cent, of water). The whole of the liquid is then titrated, 
using phenolphthalein as the indicator, until the aqueous layer is 



84 LUBRICANTS 

colourless. The total acid required is subtracted from the amount 
corresponding to the sodium h\droxide added ; the difference repre- 
sents the acidity of the oil. 

S. U the dyestuff is insoluble, or nearly so, in alcohol, it is often 
possible to extract the oil with hot 80 per cent, alcohol ; the (almost) 
colourless extract can then be titrated. 

Oils containing soap as well as colouring matter may be dealt with 
directly either by method y or ; but it is better, whenever possible, to 
free the oil from soap by extraction with petroleum spirit or anhydrous 
acetone. 

Mineral acids can be detected just as easily in d}'cd as in undyed 
oils by means of methyl orange, since the dyestuffs do not pass into 
aqueous solution. 

In dyed oils which contain Fatty Admixtures, the determination of 
acidity may be conducted by methods a, y, or 0. Method /3 is inad- 
missible, since the fatty matter may become hydrolysed by concentrated 
hydrochloric acid. 

Thus the acidity in a blue-black leather grease, consisting of waxes, 
oil of turpentine, and dyed with nigrosine, was determined by boiling 
up 5 g- of the grease with petroleum spirit, allowing to cool, and 
filtering ; this operation was repeated several times. Most of the dye 
remained in the residue, the solutions being only slightly coloured. 
They were then repeatedly extracted with dilute hydrochloric acid, 
washed thoroughly with water, and titrated. 

Differentiation of Naphthenic and Fatty Acids. — To ascertain 
whether the free acids present in an oil are naphthenic or fatty acids, 
Davidsohn ^ has recourse to the solubility in water of the alkali-earth 
salts of the latter. The alkali-soap is dissolved in water, an excess of a 
10 per cent, magnesium chloride solution added, the whole boiled, and 
the precipitate filtered off. The filtrate is concentrated on the water- 
bath, and treated with a few drops of hj'drochloric acid, when the 
presence of naphthenic acids is indicated by the solution becoming 
strongly turbid. 

IX. ROSIN IN LUBRICATING OILS. 

Qualitative Detection. — The presence of rosin in mineral oils is 
indicated by high acidity. An acidity of i per cent, of SO3, or an acid 
value of 14, corresponds to about 9 per cent, of rosin (colophony). 
Rosin is characterised by an acid value of from 146-170, a saponifica- 
tion value of from 167-194, and an iodine value of from 100-125. 

In order to isolate the rosin, the oil is thinned with petroleum spirit 
and extracted repeatedly with dilute sodium hydroxide solution. From 

' Seifensieder Zeit.y 1909, Nos. 51 and 5a. 



"GUMMING" OF OILS 85 

this solution the rosin is separated by mineral acid. It is identified by 
the above characteristics, its specific gravity, and by means of the 
Liebermann-Storch colour reaction (see " Detection of Rosins in Oils," 
this Vol., p. 130). For this test the substance is dissolved in a little 
acetic anhydride, and a drop of sulphuric acid of sp. gr. 1-53 added; 
colophony gives a violet coloration. 

The Quantitative Determination of Rosin. — If fatty oils and fatty 
acids are absent, this is effected by extracting the oil with sodium 
hydroxide solution, acidifying the solution, and weighing the separated 
rosin ; when fatty matter is present as well as rosin, the separated mass 
contains both. The rosin is then separated from the fatty matter by 
Twitchell's process (see " The Determination of Rosin in Soap," this 
Vol., p. 195). 

For this purpose so much oil is weighed or measured out that 
about 5 g. of rosin and fatty acids will be obtained. The mixture is 
saponified by means of alcoholic alkali, and the soap solution thus 
obtained is freed from unsaponifiable matter by extraction with ether 
or petroleum spirit, and is then evaporated to dryness ; the residue is 
taken up with water, acidiQed with hydrochloric acid, and extracted with 
ether. The aqueous liquid is again neutralised, evaporated to about 
25 CO., acidified, and again extracted with ether. The combined 
ethereal extracts are then evaporated down. The residue is then 
subjected to the Twitchell process as described under " Soap," this Vol., 
p. 195. 

X. LIABILITY TO "GUM" OR " RESINIFICATION " OF LUBRICANTS. 

Pale mineral oils, on exposure in thin layers, volatilise almost 
completely at 100° within thirty-five hours. 

Dark oils containing still residues scarcely thicken at ordinary 
temperatures, even after a very long time ; but at 50''- 100" they are apt 
to resinify to a considerable extent, since the more volatile hydrocarbons 
partly evaporate off and partly become oxidised, leaving a residue 
of pitch-like bituminous matter. 

In order to test an oil in this respect, a drop is allowed to spread on 
a sheet of glass 5 by 10 cm., and kept at 50° for machinery oils, or at 
100° for cylinder oils ; from time to time, say once a day, the sample 
is cooled down and its consistency noted. 

In consequence of the modern method of ring-lubrication and the 
mode of lubrication of turbine engines, where the same oil remains for a 
long time on the bearing, the requirements of the user, as regards 
liability to gumming of oils, especially of oils subjected to high tempera- 
tures for considerable periods, have become much more stringent than 
formerly, when the oil used for lubrication ran away. Hence more 



86 LUBRICANTS 

searching methods of detennining the liabih"ty of an oil to undergo 
change are required. 

R. Kissling^ has proposed to determine the "tar number," the 
"coke number," the "tar formation number," and the "coke formation 
number," as a means of examining lubricants from this standpoint. 
The "tar number" is the term he applies to the percentage content, 
which can be extracted from the oil with hot alcoholic sodium hx-droxide 
at 80', and after acidification can be extracted from this solution with 
benzene. The "coke number" is determined on the residual oil after 
extracting the "tar," and is the quantity of "coke-like substances" 
insoluble in petroleum spirit. If the oil is heated for fifty hours to 150^, 
and the "tar" and "coke" numbers are again determined as described, 
the quantities obtained are termed the "tar formation number" and 
" coke formation " number respectively. 

As Kissling's proposals have not yet been adopted by other workers, 
it will suffice to record the following results : — 

Pennsylvanian oils. Sum of tar and coke formation numbers . 0-2 to 0-5 
Russian oils „ „ „ . 1-2 

Texas oils „ ,, „ . 2-2 to 28 

The higher these numbers in an oil, the more rapidly it is found to 
undergo changes in practical use. 



XI. FORMOLITE REACTION (A. NASTJUKOFFS TEST).2 

For the determination of the unsaturated cyclic hydrocarbons in 
a mineral oil, Nastjukoff treats the oil with formaldehyde in presence of 
concentrated sulphuric acid, whereby a solid yellow product is separated 
for which the name " formolite " has been proposed. The " formolite- 
number" is the amount of air-dry "formolite" obtained from 100 g. of 
an oil. 

The test is carried out by adding 30 c.c. of concentrated sulphuric 
acid to the same quantity of the oil, and then, without shaking, adding 
15 c.c. of a 40 per cent, formalin solution, whilst cooling the mixture. 
When this has cooled to the ordinary temperature, it is poured 
into water, neutralised with ammonia, filtered off on a Buchner funnel, 
and washed, first with petroleum spirit or ether, and then with hot 
water. After drying in an oven at iio''-ii5'' the product is bright 
yellow to dark brown in colour, amorphous, and, according to Nastjukoff, 
insoluble in the usual solvents ; V. F. Herr, however, found it to be 
distinctly soluble in a large quantity of hot chloroform (i : 100), and has 
suggested applying the test directly to crude oils without previously 

1 Chem. Zeit., 1906, 30, 932; 1907, 31, 328 ; 1908, 32, 938 ; and 1909, 33, 521. 
- Petroleum, 1909, 4, 1336, 1397, 



THE FORMOLITE REACTION 87 

treating the oils with sulphuric acid, as Nastjukoff does. Herr 
obtained the following values : — 

Table 19. 



Crude oil from 


Formolite number. 


Binagdy .... 
Bibi-Eybat .... 
Balachany .... 


63-3 
28-3 
21-3 



These figures correspond to the chemical behaviour of the oils, as 
the Balachany oil is the richest in naphthenes, and the naphthenes 
do not yield " formolite." This reaction furnishes valuable practical 
information as to the working up of crude naphtha. 

The formolite numbers of various American and Russian lubricating 
oils (cylinder oil, machine oil, spindle oil, vaseline oil), given by 
Nastjukoff,^ show that all these oils consist essentially of unsaturated 
cyclic hydrocarbons. Thus American cylinder oils gave formolite 
numbers of 92-97, Russian cylinder oils of from 58-87, and vaseline oils 
of from 7-8-22. 

Herr- has recently pointed out that formalin maybe advantageously 
replaced by methylal CH2(OCH3).„ as the latter acts at the same time 
as a solvent for the oil, and as a condensing agent, and, moreover, forms 
a better condensing agent for the detection of benzene hydrocarbons 
than does formaldehyde. 

XII. BEHAVIOUR TOWARDS METALS. 
Corrosion of bearings by machinery and axle oils never takes place 
to an appreciable extent at ordinary temperatures, unless fatty oil 
containing free acid is present. Comparative tests, carried out first 
by I. I. Redwood,^ may be made by immersing polished and weighed 
plates of the metal concerned, 30 or 50 mm. square, in the oil contained 
in glass or porcelain basins, and heating them, protected from dust, in an 
air-bath. From time to time during the period of the test, which may 
be continued for weeks, the plates are cleaned with tissue paper and 
ether, inspected, and weighed. It must, however, be pointed out 
that these tests by no means furnish reliable guidance as to the 
behaviour of the oils on a practical scale. 

XIII. MOISTURE. 

Qualitative Detection. — The presence of moisture in pale oils is 
usually indicated by a more or less pronounced cloudiness, especially 

1 Petroleum, 1909, 4, 1336, 1397. 

2 Chem. Zeit., 1910, 34, 893 ; J. Soc. Chem. Ind,, 1910, 29, 1094. 

'^ J. Soc. Chem. htd., 1886, 5, 362. 



88 LUBRICANTS 

after the sample has been shaken. By heating on the water-bath, the 
oil loses its cloudiness, which dififerentiates it from the cloudiness caused 
by the separation of paraffin wax, etc. 

Quantitative Determination. — From 10-12 g. of the sample are 
weighed into an open glass or porcelain dish of 6-10 cm. diameter; if 
much moisture is present, 3-5 g. are weighed out and mixed with lo-i 5 g. 
of the same oil, previously dehydrated with calcium chloride and 
filtered. The dish is heated on a briskly boiling water-bath until no 
more froth is formed, when the oil is stirred with a glass rod. Side by 
side another sample, but which has been previously dehydrated, is treated 
in exactly the same way. The percentage loss in weight of the latter is 
subtracted from that of the former ; the difference represents the moisture 
in the original sample. In the case of practically non-volatile cylinder 
oils, the blank test may be omitted. 

XIV. MINERAL ASH. 

No ash is obtainable if the oil is completely soluble in petroleum 
spirit and benzene, and the aqueous and hydrochloric acid extracts of 
the oil give no perceptible residue on evaporation. Well-refined 
machine oils should not contain more than o-oi per cent., and cylinder 
oils not more than o-i per cent, of ash, which should not, however, 
contain any appreciable quantity of alkali. 

For the determination of the ash 20-30 g. of the oil are carefully 
evaporated in a platinum dish over a small flame, until the residue is . 
solid ; this is incinerated and the residual ash weighed. If the 
carbonaceous residue is difficult to burn off by simple heating, the 
combustion is assisted by adding ammonium nitrate. 

XV. PRESENCE OF SOAP. 

It has been pointed out above that solid lubricants contain alkali- or 
lime-soaps which are purposely added. 

The presence of alkali-soap is indicated by the oil, on being 
shaken with water, giving an emulsion having an alkaline reaction to 
phenolphthalein. 

After acidification with a mineral acid, sodium or potassium may 
be detected by the usual methods. The presence of ammonia-soaps 
is recognised by the smell of ammonia (see also p. 103). Lime- 
or alumina-soaps are best tested for in an acid extract of the 
oil. 

Quantitative Determination. — For the quantitative determination of 
soap, use is made of the fact that, by agitating the sample with mineral 
acid, the soap is decomposed, its equivalent amount of free fatty acid 



ADMIXTURES OF FATTY OILS 89 

being dissolved by the oil, the total acidity of which is then greater by 
that amount than its original acidity. The nature of the soap-acids 
may be ascertained by isolating them and examining them according to 
the methods described in the following Section. The soap-bases are 
identified in the aqueous solution. 

To carry out the determination lo c.c. of the oil are dissolved in a 
separating funnel in 40-60 c.c. of ether. The solution is thoroughly shaken 
with so much dilute hydrochloric acid that the aqueous layer remains 
distinctly acid. The latter is separated off, and the residue repeatedly 
washed with water until free from acid. Any emulsions formed are 
broken by adding more ether or a strong solution of common salt, or a 
little alcohol, which is poured on without shaking. 

If the emulsion persist, nevertheless, warm petroleum spirit is 
substituted for ether, and the solution washed with w^arm water. 
Separation having been effected, the ethereal solution is titrated for 
acidity as described on p. 82. Finally, the acidity of the original oil is 
determined ; the difference between the two acidities corresponds to the 
amount of fatty acids present as soaps. 

XVI. ADMIXTURES OF FATTY OILS. 

To detect the presence of fatty oils rapidly, 3-4 g. of the sample are 
heated in a test tube with either sodium or sodium hydroxide for a 
quarter of an hour in a paraffin-bath, pale oils to 230'', dark and cylinder 
oils to 250°. In the presence of 0-5 per cent, of glycerides in pale oils, of 
2 per cent, in dark oils, a formation of soapy froth will be observed, and 
the oil will gelatinise on cooling. 

It should be pointed out, however, that gelatinisation may take 
place without frothing, if rosin and naphthenic acids are present. 

Quantitative Determination. — The percentage of fatty oil is 
determined quantitatively by heating 10 g. of the sample for half an 
hour with 25 c.c. of 2/A^ alcoholic potassium hydroxide and 25 c.c. of 
benzene under a reflux condenser; 25 c.c. of water are then added, 
and the solution is washed into a separating funnel with 50 per cent, 
alcohol. The soap solution is shaken out several times with 50 c.c. of 
low-boiling petroleum spirit, until the last extract leaves no oily residue 
on evaporation. The united petroleum spirit extracts are shaken out 
three times successively, with 15 c.c. of 50 per cent, alcohol to which 
a trace of alkali has been added. This alcohol extract is shaken out 
once with petroleum spirit, and is then added to the soap solution. 
The petroleum spirit solutions are evaporated, and the residue heated 
on a water-bath until the solvent is driven off completely. After 
drying for five minutes at 100" the mineral oil thus obtained is 
weighed. The difference between the amount of mineral oil thus 



90 LUBRICANTS 

found and the quantity of oil originally taken gives the content of 
saponifiable fat. 

If approximate data suffice, it is simpler to determine the saponifica- 
tion value of the sample (see next section, " Saponification Value," 
p. 114). 

For this purpose 4-10 g. of the oil are heated for half an hour under 
a reflux condenser with 25 c.c. of A^/2 alcoholic potassium hydroxide, or, 
in the case of very thick oils, 25 c.c. of A^'i potassium hydroxide and 
the same volume of benzene. The excess of alkali is then titrated back 
with NI2 hydrochloric acid, using phenolphthalein as the indicator, and 
the saponification value calculated as described in the next Section, 
p. 115. 

For the calculation 195 may be taken as a mean saponification value 
of the oils that come under consideration, with the exception of rape 
oils, for which 175 should be taken; the saponification value of mineral 
oil is, of course, nil. Hence, e.g., if the sample has the saponification 
value 97-5, the percentage of fatty oil, if rape oils be absent, is 50 per 
cent. Any alkali necessary to neutralise free acid in the oil (acid value) 
must, of course, be deducted from the saponification value, and the 
difference calculated to glycerides. 

For exact determinations the fatty acids are separated and examined 
as described in the following Section, p. 130. 

In the presence of wool grease (the saponification value of which 
is about 105), a complication arises owing to the higher alcohols of the 
wool grease remaining with the unsaponifiable mineral oil. In this 
case the latter is boiled, after removal of the soap solution, with an 
equal weight of acetic anhydride for two hours under a reflux condenser, 
whereby the alcohols are converted into esters. These remain dissolved 
in the warm acetic anhydride solution which is separated off; the 
mineral oil is then washed several times with a few cubic centimetres 
of warm acetic anhydride in a separating funnel. From 3-5 per cent, 
of mineral oil are lost in this process, and must be duly taken into 
account. Owing to the fact that wool grease itself contains hydro- 
carbons, and further that it is not completely saponified by boiling with 
alcoholic alkali, quantitative determinations of wool grease by the 
method described above, yield only approximate results. 

The Identification of the Fatty Matter. — This is carried out by 
the methods described in the following Section, pp. 130 et seq. 

XVII. ROSIN OILS AND TAR OILS. 

Rosin Oils. — Heavy rosin oils, boiling above 3CX)°, are produced by 
the destructive distillation of colophony, light rosin spirit or pinolin 
coming over in the first runnings. 



ROSIN OILS AND TAR OILS 91 

Crude rosin oil is mainly a mixture of hydrocarbons (which consist, 
according to Bruhn and A. Tschirch/ principally of reduced retenes) ; 
according to the care with which it has been distilled it may contain up 
to 30 per cent, of rosin acids. 

Crude and refined rosin oils find application as electrical insulators, 
and in the manufacture of lubricants, varnishes, and water-soluble oils. 

Rosin oil dissolves in twice its volume of absolute alcohol to the 
extent of 50-100 per cent,, in mineral oils to 2-15 per cent., and in very 
light mineral oils to 35 per cent. It is miscible in all proportions with 
acetone, whereas mineral oils require several volumes for complete 
solution. 

The refractive index of rosin oils is I-535-I-550 at 18", that of mineral 
oils I-490-I-507. The specific gravity varies from o-88o-o-9i5. Rosin 
oils are strongly optically active: [ajo ranges from +30° to +50°; 
mineral oils, on the other hand, are as a rule inactive, or at most have 

The iodine value of rosin oils varies from 43-48. It may be pointed 
out that cracked petroleum distillates have iodine values, sometimes 
reaching 70. 

When a few cubic centimetres of rosin oil are shaken with an equal 
volume of sulphuric acid of sp. gr. i-6, a deep red colour results. This 
colour reaction is due to impurities which are absent from well-refined 
rosin oils, such as are now placed on the market. 

On adding to a mixture of i c.c. of oil and i c.c. of acetic anhydride 
a drop of sulphuric acid of sp. gr. 1-53, a fine violet colour is produced 
(Liebermann-Storch reaction, see p. 130). This reaction is given by 
rosin as well as by rosin oil. When both are present together rosin 
oil may be detected by its odour, and by the further characteristics 
described below. 

If a lubricating oil is suspected of containing rosin oil, the examina- 
tion must be based on the properties described above ; if necessary, the 
tests are performed on that portion of the lubricant which is soluble in 
absolute alcohol in which the rosin oil is much more soluble than the 
mineral oil. 

Determination of Rosin Oil in Mineral Oils. — The best method for 
this determination is that of E. Valenta, which is based on the difference 
in the solubilities of rosin oils and mineral oils in glacial acetic acid at 
50"; 10 c.c. of glacial acetic acid dissolve 17788 g. of the former, and 
from 0-2833-0-6849 g. of the latter. 

For the determination, 2 c.c. of the unsaponifiable matter are mixed 
in a test tube with 10 c.c. of glacial acetic acid, and the tube, loosely 
closed by a cork, is immersed in a water-bath at 50° for five minutes 

^ Chem. Zeit., 1900, 34, 1105 ; Arc/i. P/iaim., 1903, 291, 523. 
2 Rakuzin, C/iem. Zeit,, 1904, 38, 574. 



92 LUBRICANTS 

the contents being frequently shaken. The mixture is then filtered 
through a moistened filter, and the middle portion of the filtrate 
collected. Part of this is then weighed off accurately, and the content 
of acetic acid determined by titration with Nji sodium h}-droxide. 
The difference between the weight of the acid taken and the weight 
thus found corresponds to the quantity of rosin oil dissolved. 

The accuracy of this method has been confirmed by J. H. Walker 
and C. D. Robertshaw.^ 

Rosin acids, if present in the rosin oil, influence the solubility, and 
render the determination inaccurate. In this case, the greater part of 
the acetic acid is neutralised, the solution diluted with water, and the 
rosin oil extracted with ether,^ 

According to the method due to L. Storch,^ which applies only in 
absence of fatty oils, lo g. of oil are well shaken with five parts of warm 
96 per cent, alcohol. After cooling, the alcoholic solution is separated 
off, and the residue washed with a small quantity of the solvent. The 
combined solutions are evaporated in a tared conical flask and heated 
on the water-bath till free from alcohol. The weighed residue (A) is 
then treated with ten parts of alcohol, and the substance dissolved is 
again isolated and weighed (B). There will still be some mineral 
oil in B, and its amount is calculated as follows : — Suppose a grams 
of alcohol to have acted upon the original material, and b 
grams upon A; then a-b grams dissolve A-B grams of mineral oil; 

therefore b grams dissolve ^ j— grams of the same. This 

latter amount is worked out and subtracted from B, and thus gives 
the quantity of rosin oil in the original 10 g. of mixed oil. 

Detection of Mi)ieral Oil in Rosin Oil. — Mineral oils afford no very 
characteristic qualitative reactions, and when there is less than 15 per 
cent, in a sample of rosin oil, no information can be gained by the 
ordinary solubility methods. Holde's procedure for detecting small 
admixtures of mineral oil is based on differential solubilities and on 
differential refractivities. According to this method 10 c.c. of oil are 
shaken up with 90 c.c. of 96 per cent, alcohol at the ordinary temperature. 
If any considerable amount of oil remains undissolved, the presence of 
much mineral oil is indicated. In this case the insoluble oil is allowed 
to settle out overnight, rinsed with alcohol, and tested by the refracto- 
meter. A refractive index of less than 1-533 ^^ ^8° is evidence of 
mineral oil. 

Heavy rosin oils lose much more weight at loo'^ and iSo' than 
mineral oils, even than light spindle oils. Similarly the flashing point 

1 Anatys/, 1902, 27, 238. 

^ A. H. Allen, Commercial Organic Analysis, 2nd ed., vol. ii., p. 465. 

^ Ber. Osterr. Gesell. z. Forder. der Cliem. Ind., 1891, 9, 93 ; /. Soc. Chem. I mi., 1 891, 10, 276. 



COAL-TAR OILS 



93 



of rosin oil is relatively lower. The following Table affords some 
guidance for examination : — 

Table 20. 





Loss on heating (per cent.). 


Flashing point. 


For 5 hours 
at 100°. 


For 2 hours 
at 170°. 


Peusky. 


Open test. 


Heavy rosin oil 

Spindle oil . . . 

Machinery oil . 


0-4 to 0-8 
0-05 „ 0-10 
0-06 „ 0-13 


5-6 to 7-4 
0-5 „ 1-8 
0-6 „ 1-05 


109° to 146° 
177° „ 203° 
188° „ 195° 


148° to 162° 
189° „ 213° 
205° „ 221° 



Coal-tar Oils. — The oils which come under consideration here and 
which are used as lubricants in gas-suction pumps and as ingredients 
of lubricating greases, are the dead anthracene oils, heavier than water, 
and having a characteristic smell of creosote. They are completely 
soluble in alcohol at the ordinary temperature, and are dissolved by 
concentrated sulphuric acid on the water-bath forming compounds 
soluble in water. With - nitric acid of sp. gr, 1-45 they yield nitro- 
products with evolution of heat and sometimes with almost explosive 
violence. The following method for their determination, which gives 
approximate results, has been based on the rise of temperature 
produced by this treatment: — 7-5 c.c. of the sample are placed in a 
graduated tube, cooled to 15°, and 7-5 c.c. of nitric acid of sp. gr. 1-45, 
previously cooled to 15° added; the tube is closed by a cork provided 
with a thermometer, the contents thoroughly shaken, and the rise of 
temperature read off It is well to try a preliminary test always, in 
order to ascertain whether a violent reaction takes place or not, as a 
guide to the quantity of the sample to be taken, and the size of the tube 
to be employed for the test. 

For the differentiation of coal-tar oils from mineral oils the reaction 
proposed by E. Valenta^ may be used. This depends upon the 
solubility of benzene hydrocarbons as found in coal-tar in dimethyl 
sulphate (SOo(OCH3).,) at the ordinary temperature, and the insolubility 
of crude petroleum, benzine, illuminating oil, mineral oil, and rosin oil. 
A certain quantity of the oil is shaken for a minute in a measuring 
cylinder with i|-2 vols, of dimethyl sulphate and allowed to separate, 
whereupon the difference of volume is read off 

This method has been tested by E. Graefe,^ who found that it gave 
almost theoretical values in the case of mixtures of high-boiling coal-tar 
and mineral oils, but that in the case of very low-boiling petroleum 
derivatives, the solubility in dimethyl sulphate is appreciable. In 

1 Chein. Zeit., 1906, 30, 266 ; J. Soc. Chern. Ind.^ 1906, 25, 366. 
2 Chem. Rev. Fetl-Ind., 1907, 14, 1X2. 



94 LUBRICANTS 

lignite-tar oils a constant error of approximately lo per cent, occurs ; 
but if this be taken into account, the separation of coal-tar and lignite- 
tar oils can be effected by this method. The method has also been 
examined by T. W. Harrison and F. IM. Perkin/ who found that 
aromatic oils are soluble in dimethyl sulphate in all proportions, but 
that mineral oils are not insoluble. Thus 8-5 per cent, of Russian 
petroleum was dissolved by its own volume of the reagent, and by 
repeated extraction with fresh quantities as much as 80 per cent, 
could be dissolved. Hence it is concluded that the method cannot be 
applied quantitative!)', although of value as a qualitative test. 

Heavy Lignite Oils {cf. the section on "Mineral Oils," p. 53) have 
a sp, gr. of 0-89 0-97, and dissolve to the extent of 20-60 per cent, when 
shaken with 2 vols, of cold alcohol; the viscosity is usually low. These 
oils have a faint smell of creosote ; their properties are, on the whole, 
not sufficiently well-marked to render them certain of detection. 

XVIII. INDIA RUBBER. 

The presence of india rubber in lubricating oils may be recognised 
by their tendency to run into threads when drawn out by a glass rod, or 
between the fingers. A rough determination of the india rubber may be 
effected by dissolving the oil in ether and precipitating with absolute 
alcohol. If present in a homogeneous dissolved condition, india rubber 
may be regarded as a perfectly harmless ingredient, since it neither 
attacks metals nor tends to thicken ; it has the effect of rendering the' 
oil peculiarly slippery and adhesive. 

As yet there is no standard method of determining the amount of 
india rubber in lubricating oils. Methods based on the formation of 
addition products, insoluble in acetone, either with nitrous acid or with 
hyponitrous acid, have not yet been worked out for the estimation of 
india rubber in oils. 



XIX. DEBLOOMING AGENTS AND PERFUMES. 

Mono-nitronaphthalene, CidH-NO.„ is added to mineral oils to mask 
the fluorescence, whilst the presence of an objectionable smell is over- 
come by the addition of nitrobenzene. The latter is recognised at once 
by its characteristic odour of bitter almonds. Yellow coal-tar dyes, 
which are also used similarly to nitronaphthalene, are indicated by their 
deep yellow colour. Oils treated with nitronaphthalene become darker 
on keeping. 

Detection of NitronaphtJialene. — As a preliminary test from 1-2 g. 
of the oil are boiled with 2-3 c.c. of concentrated alcoholic potassium 

' Analyst, 1908, 33, 2. 



IMPURITIES IN LUBRICANTS 95 

hydroxide (about 2/A^) in a test tube for a minute or two. In the 
presence of nitronaphthalene or nitrobenzene the liquid becomes blood- 
red or even violet, owing to the formation of azo-compounds. The 
reaction is especially well observed when drops of the liquid adhering to 
the upper part of the test tube are gently warmed. 

If the colour test has given a positive indication, the following con- 
firmatory test proposed by N. Leonard may be applied.^ A few cubic 
centimetres of the oil arc placed in a conical flask, and reduced by warming 
with tin and hydrochloric acid for five to ten minutes. A piece of platinum 
wire may with advantage be placed in the liquid. The acid aqueous 
solution is separated from the oil, filtered into a separating funnel, and 
treated with sufficient potassium hydroxide to neutralise the acid and 
redissolve the stannous hydrox'de precipitate. The presence of nitro- 
naphthalene in the original oil is indicated by the characteristic unpleasant 
smell of a naphthylamine. This is extracted with 10-20 c.c. of ether and 
the ethereal solution evaporated in a glass dish. Naphthylamine then 
remains as a malodorous oil of a violet colour. On adding a drop of 
hydrochloric acid a semi-solid mass of the hydrochloride is formed ; this, 
after evaporating off the excess of acid, gives a clear solution in water. 
The solution yields with ferric chloride a bulky blue precipitate which 
when filtered off, assumes a reddish-purple colour, whilst the filtrate 
shows a fine violet tint. 

XX. WATER-SOLUBLE SUBSTANCES. 

Glue occasionally finds its way into mineral oils from carelessly 
glued casks. It is detected as follows : — 100 g. of the oil are thoroughly 
shaken up with boiling water in a conical flask, the aqueous layer 
separated off and an aliquot part, say 60 c.c, filtered into a measuring 
cylinder, and evaporated to dryness in a glass dish on the water- 
bath. If there is an appreciable residue which, whilst hot, seems to 
smell of glue, it is extracted two or three times with 5-8 c.c. of hot 
absolute alcohol, whereby any soap, if present, is removed. The dried 
residue may be weighed. If it consists mainly of glue, the characteristic 
smell given off on heating, as also the precipitate obtained from its 
aqueous solution by tannic acid, serve as confirmatory tests. 

Sodium sulphate, to which (a rarely-occurring) opacity or the break- 
ing of mineral oils may be due, is detected in an aqueous extract by 
means of barium chloride. 

XXL SUSPENDED MATTER. 
Mechanical Impurities are detected in pale oils by mere inspection. 

1 Chem. News, 1S94., 68, 297 ; J. Soc. C/iem. ImL, 1 891, 13, 69. 



96 LUBRICANTS 

For their quantitative determination, 5-10 g. of the sample are 
dissolved in 100 c.c. of petroleum spirit, or in the case of dark oils in 
benzene. After standing overnight the solution is poured through a 
tared filter, and the residue washed thoroughly with the same solvent. 
The filter is then dried at 105° and weighed. 

Bituminous and Pitch-like Matter in suspension in dark oils, 
beside mechanical impurities, is determined as described in the section 
on " Mineral Oils," p. 10. 

Vaseline, Paraffin, Iron-soap, etc. — These may be detected in 
the residue after filtration by methods varying with the character of the 
sample. Iron-soap, which is a not uncommon impurity, is easily 
recognised by the formation of ferric oxide on ignition. 

XXII. ASPHALT AND PARAFFIN IN SOLUTION. 

The determination of asphaltic substances and paraffin wax, which 
must be considered as normal constituents of lubricating oils, is carried 
out by the methods described under " Crude Petroleum " in the section 
on " Mineral Oils," p. 9. 

XXIII. CHANGES LUBRICATING OILS UNDERGO IN USE. 

Recovered Oils. — For reasons of economy, used lubricating oils are 
collected and again used after some process of purification, whereby 
mechanical impurities and moisture are removed. In the laboratory 
water is removed by prolonged warming in a salt-bath, or by adding 
calcium chloride. 

The recovered oils are, as a rule, darker than the original oils. 
Recovered cylinder oils, containing fatty oils, usually show a notable 
amount of free fatt)' acid, asphaltic substances, and of iron-soap ; the 
last-named impurity causes a slight increase of specific gravity and 
viscosity. 

Solid residues found in slide valves, etc.,^ are extracted first 
exhaustively with chloroform. The insoluble residue is treated with 
hydrochloric acid, which decomposes iron-soaps and dissolves iron 
oxide. The substances insoluble in the acid consist generally of 
carbon, sand, etc. ; of these the carbon is determined by incineration. 
The portion dissolved by chloroform is treated with petroleum spirit ; 
the insoluble portion is generally identical with the original lubricating oil 
in specific gravity and elementary composition. The portion insoluble 
in petroleum spirit is usually soluble in benzene, and consists of asphaltic 
substances. 

1 Cf. G. Worrall and J. E. Southcombe, /. Soc. Chem. InJ., 1908, 27, 308 ; J. E.Southcombc, 
/(^/f/., 191 1, 30, 261. 



VASEUNE 97 

Condenser Water being frequently used as feed water for the boilers, 
the removal of the emulsified oil by some process of purification is 
imperative. To test the efficiency of the purifying plant the oil content 
in the water, after filtering, is determined by extracting 1-2 litres 
of the water exhaustively in a separating funnel with freshly distilled 
ether. The extracts are filtered through a filter paper, the ether 
distilled off, and the residue dried for ten minutes at 105° and weighed. 
In view of the small quantities obtained, all sources of error must 
be guarded against. 

E. Graefe recommends the precipitation of the oil in the water by 
means of alumina or ferric hydroxide, and the extraction of the oil from 
the precipitate. 

B. FATTY OILS. 

Since mineral oils have been introduced the use of pure fatty 
oils as lubricants has been greatly restricted. Nevertheless, consider- 
able quantities are still used, either as such or in admixture with 
mineral oils. 

The suitability of a fatty oil for lubricating purposes is gauged by 
the purity of the oil, which is ascertained by the methods given 
in the following Section on " Oils, Fats, and Waxes." 

C. MIXTURES OF MINERAL AND FATTY OILS. 

Mixtures are dealt with, in the main, by the methods described in 
the previous section on " Mineral Oils." When it is desired to separate 
the fatty and mineral oil constituents quantitatively, the procedure given 
on p. 89 is followed. 

D. VASELINE. 

Two kinds of vaseline are known in commerce. The one is prepared 
from crude American petroleum by slow distillation of the volatile 
fractions and purification of the residue by means of acid or Fuller's 
earth (Chesebrough vaseline). The other is compounded by dissolving 
paraffin wax and ceresin in colourless petroleum oils (artificial vaseline, 
German vaseline). Though used principally for cosmetic and pharma- 
ceutical purposes, vaseline is also, to some extent, applied as a lubricant 
and as a rust preventative. The laboratory methods for testing vaseline 
do not differ from those which hold good for petroleum derivatives 
generally. The specific gravity is best measured at 100° by means of a 
hydrostatic balance, the thermometer plummet of which has a range 
reaching to 100" ; or, it may be determined with a Sprengel pyknometer. 
Chesebrough vaseline is stated to have a sp. gr. of 0-845, artificial 
vaseline of 0-827, both at 100'. 

Ill G 



98 



LLliUICANTS 



Distinction between Natural and Artificial Vaseline.' — A com- 
parison of the viscosities gave the following values : — 



Material. 


Viscosity (Engler). 


45°. 


60*. 


80°. 


100'. 


Natural American vaseline . 
Artificial vaseline 


4-8 
does not flow 


3-7 

does not flow 


2-1 
1-5 


1-6 

1-2 



Artificial vaseline did not flow in the Engler apparatus even at 65", 
whereas when completely molten at 80", and 100 , it is much more fluid 
than natural vaseline. 

Differences are also observed in the absorption of o,x)-gen. Engler 
and Bohm heated quantities of 11-15 g. of vaseline with the addition of 
2-3 c.c. of water in sealed tubes, with 53-76 c.c. of oxygen for twenty- 
four hours at 1 10 -i 15", with the following results : — 



Material. 


Absorption of oxygen. 


Quantity of .N'/IO alkali required 

to neutralise the acid from 

100 g. of vaseline. 


Natural vaseline . 
Artificial vaseline 
Hog's lard .... 


35-0 to 46-5 c.c. 

4-2 „ 4-7 „ 

42-0 „ 50-0 „ 


5-5 to 10-5 mg. KOH 
0-7 „ 1-4 
31-0 ., 39-0 



E. SOLID LUBRICANTS. 

The substances included under this head vary widely in their nature 
and composition. General methods of examination, therefore, cannot 
well be laid down, and it is necessary to modify the laboratory tests 
according to the nature of the products concerned. Some data as to 
the composition of solid lubricants have been given above (p. 59). 
Some varieties melt at 6o'-65^ whilst others do not become liquid until 
temperatures well over 100" are reached. 

The following are the main features to be taken into account with 
regard to solid lubricants: — 

I. Appearance^ etc. 

I I. Liquefying and Dropping points. 

III. Qualitative Composition. 

IV. Quantitative determination of: — 

{a) Free Fatty Acid, {h) Soap, {c) Neutral Fats (glycerides) 
and unsaponifiable matter (Mineral Oil, Rosin Oil, Wool 
Grease, etc.). {d) Water, {e) Glycerol. (/) Nitrobenzene 
and Nitronaphthalene. (g) Free Lime. (//) Impurities 
and adulterants. 

' C/. Engler and Bohm, Dingl. polyl. J., l8S6, 262, 468. 



SOLID LUBRICANTS 



99 



L Appearance, etc. 

A good deal of information as to quality may be gained by inspection. 
Properly compounded greases should be quite uniform with respect to 
colour and consistency. Additions of rosin oil, tar oil, 
nitrobenzene, etc., may be detected by the smell. 




ir> - o 



o 



o 



IL Liquefying and Dropping Points. 

The temperature at which lubricating greases become 
fluid ranks as one of the most important criteria in their 
commercial valuation. 

These greases do not possess a definite melting point. 
When warmed, they at first gradually soften at the sur- 
face ; when further heated, the soap may remain sus- 
pended in the molten fatty matter, and complete melting 
may only occur when a portion of the moisture has been 
lost by evaporation. 

The most serviceable method for the determination 
of the liquefying and _ dropping points is that of L. 
Ubbelohde, in which the temperature is ascertained at 
which a drop of the sample detaches itself by its own 
weight from the uniformly heated mass.^ 

The apparatus (Fig. 32) consists essentially of a ther- 
mometer a, to which is closely fitted a metal cylinder b, 
and a small glass receptacle ^, 10 mm. long, and having 
an opening of 3 mm. bore. The metal cylinder has a 
small opening at c, and grips both the thermometer and 
the receptacle firmly. 

To carry out the test the substance under examination 
is pressed into the receptacle, and the excess struck off 
neatly with a knife ; the receptacle is then fitted to the 
thermometer, as shown. In the case of paraffin wax and 
ceresin, the substance is first melted (with a glass plate 
held under the receptacle) and the thermometer inserted 
before it has solidified. Three small guides d prevent ^- 
the thermometer from being pushed down too far. The 
thermometer is fixed by means of a cork in a test tube 
of 4 cm. bore, which is placed in a water-bath (a 3 litre 
beaker filled with water) and heated slowly so that the 
temperature rise per minute does not exceed 1°. 

The temperature at which a drop of the melted lubricant begins to 
make its appearance is noted as the " Liquefying point," and that at 

1 Z. angew. C/iein., 1905, 18, 1220 ; /. Soc. Cliem. Ind„ 1905, 24, 941. The apparatus 
is supplied by Messrs Bleckmann and Burger, Berlin. 



O 



fiP- 



<S 



o 



o 



^CL 



W- 



^a 



FlQ. 32. 



100 LUBRICANTS 

which the first drop falls as the " Dropping point," The latter point is, 
as a rule, from 3^-6 above the liquefying point, although in some cases 
the difference may amount to 15 and even more. 

III. Qualitative Examination. 

If the lubricant should be completely soluble in petroleum spirit 
or ether, and leave no ash on incineration, it is only necessary to test 
for rosin and possibly for ceresin, as described on pp. 84 and 187. 

The presence of water is indicated by the spurting that occurs on 
incineration. 

The examination of the fatty matter is carried out by the methods 
described in the following Section (pp. 1 14 r/ seq). 

As the majority of lubricating greases contain soap, and are therefore 
only partially soluble in petroleum spirit, the sample is treated with 
a hot mixture of 9 vols, of petroleum spirit, and i vol. of absolute 
alcohol and, after standing for a short time, filtered whilst still warm. 
Any insoluble residue (lime, calcium carbonate, barytes, infusorial 
earth, graphite, etc.) remains on the filter and is examined by the 
ordinary methods of inorganic analysis. 

IV. Quantitative Determinations. 

(a) Free Acid. — Free mineral acid, if present, is detected and 
estimated by titrating a hot-water extract of the grease. Free fatty* 
acids are determined by the method described in the following Section 
(p. 130). 

(6) Soap. — For this estimation 10 g. of the sample are dissolved in 
petroleum spirit, decomposed with hot, dilute hydrochloric acid, and the 
acid layer of liquid separated. This layer is sometimes coloured red 
owing to the presence of colouring matters that have been added to the 
lubricant ; in such cases the extraction with hydrochloric acid is 
repeated until a final colourless extract is obtained. If the sample is 
not coloured, two successive extractions are sufficient. After the 
separation of the acid, the residual petroleum spirit is washed either 
with water or with a solution of sodium sulphate (to avoid the 
formation of an emulsion), and titrated, after the addition of 20 
c.c. of absolute alcohol, phenolphthalein being employed as the 
indicator. 

The acid value obtained represents the sum of the free fatty acids 
present (ascertained as in {a), above) and of the fatty acids formed by 
the decomposition of the contained soap; the difference represents the 
fatty acids present as soap. This value may be calculated cither to 
sodium or to calcium soap, as the case may be. It is sufficiently 



SOLID LUBRICANTS. QUANTITATIVE TESTS 101 

accurate to take 280 as the mean molecular weight of the fatty acids ; 
should there be reason to assume the presence of rape oil, the mean 
molecular weight 310 may be adopted. 

(c) Neutral Fats (Glycerides) and Unsaponifiable Matter — The 
petroleum spirit solution obtained under {b) is freed from fatty 
acids in the usual manner by extraction with 50 per cent, alcohol, 
distilled to dryness, and the residue, consisting of neutral fats and 
hydrocarbons, is weighed. The proportion of glycerides in it is 
determined by estimating its saponification value (p. 1 14) and calculating 
to percentage of the original material. 

If the nature of the unsaponifiable matter is to be examined, this 
constituent is separated from the soap as described above. 

(cf) Water. — For most purposes it is sufficiently accurate to mix a 
weighed quantity of the grease with dried sand, and dry in a water 
oven. 

A more lengthy but more accurate method is that proposed by 
J. Marcusson, which is carried out as follows : — 100 g. of the sample are 
dissolved in 100 c.c, of xylene in a 600 c.c. Erlenmeyer flask, some 
fragments of pumice added, and the solution distilled from an oil- 
bath through a Liebig's condenser. Unless very little water is present, 
distillation begins below 100°. The distillate is collected in a 100 c.c. 
measuring cylinder, in which the separation into layers of water and 
xylene rapidly takes place. Distillation is continued until pure 
xylene comes over ; any drops of water which adhere to the con- 
denser are rinsed down with xylene. The amount of water driven 
over is read off directly and calculated to percentages of the original 
substance. 

(e) Glycerol. — The small quantities of glycerol (from. 0-5-2 per 
cent.) occurring in lubricating greases are derived from the saponifica- 
tion of the fatty constituents. The determination of glycerol is carried 
out only in exceptional cases ; the method described in the following 
Section is then employed (p. 123). 

(/) Nitronaphthalene and Nitrobenzene. — The method for the 
estimation of these substances has been described above (p. 94). 

{g) Free Lime is determined by heating 10 g. of the sample 
with 50 c.c. of benzene and 5 c.c. of alcohol for a quarter of an hour 
under a reflux condenser. The residue is filtered off, thoroughly 
washed with a hot mixture of benzene and alcohol in the above 
proportions, and the contained free lime determined by the usual 
methods. 

(/i) Impurities and Adulterants. — Plaster of Paris, barytes, starch, 
talc, graphite, lampblack, and the like remain undissolved when the 
sample is extracted with the mixture of benzene and alcohol as 
described under {g), and are determined in the residue thus obtained. 



102 LUBRICANTS 



F. WATER-SOLUBLE LUBRICANTS. 

Water-soluble lubricants have the property of forming permanent 
emulsions or almost clear solutions with water. Latterly they have 
become important articles of commerce, and are prepared by dissolving 
ammonia-, potash-, or soda-soaps of oleic, sulpho-fatty, rosin, or naph- 
thenic acids in mineral oils. Frequently ammoniacal liquor, petroleum 
naphtha, or alcohol is added ; in some cases the rosin oils are first blown 
with air. The resulting water-soluble products may be regarded as 
(colloidal) solutions of mineral oil in an acid soap solution Such 
preparations are largely employed as lubricants in boring, milling, 
lathe-cutting, and polishing operations. They have the advantage 
over aqueous solutions of soap that iron-work with which they come 
in contact does not rust so easily ; other applications are dressing 
wool-fibre in spinning and weaving, for laying dust in streets, and 
so on. 

The Solidifying" Point of such oils is, of course, lowered by the 
addition of water. Thus a mixture of 80 parts of water with 20 
parts of oil is still liquid at —5'; for this reason water-soluble oils 
are often used in place of glycerine in hydraulic presses and pressure 
mains. 

The Emulsifying Properties or Solubility in Water is determined 
by preparing solutions of varying concentration, and observing the 
permanence of the emulsion after standing for one or more da}-s. In 
the case of oils containing ammonia-soaps, the soaps gradually lose 
ammonia, and the emulsifying properties then fall. Such oils must 
therefore be tested (and kept) in well-closed receptacles. 

Analytical Examination. 

This comprises the following determinations : — 

(a) Volatile Matter (Water, Alcohol, Naphtha).— The content of 
water is determined by distilling about 20 g. of the oil in a i -litre 
Erlenmeyer flask, with the addition of 100 c.c. of xylene and small 
pieces of pumice (r/!, The determination of water in petroleum in the 
section on " Mineral Oils," this Vol., p. 5). 

The aqueous distillate is fractionated and tested for alcohol, either 
by the specific gravity of the distillate, or, if necessary, by the iodoform 
test. To determine the petroleum naphtha, the oil is decomposed by 
dilute sulphuric acid, and the volume of naphtha either measured 
directly or after being distilled over by steam. 

If both alccjhol and naphtha are present, the oil is distilled with acid 
potassium sulphate, and the distillate shaken with sodium hydroxide, 
whereby the alcohol is completely separated. The volume of naphtha 



WATER-SOLUBLE LUBRICANTS 103 

is then measured, and the alcohol separated from the alkaline liquid by 
a further distillation, and determined as above. 

(b) Free Organic Acid. — In the absence of ammonia the sample is 
titrated with iV/io alcoholic sodium hydroxide. 

In the presence of ammonia-soaps, it is necessary to determine the 
ammonia by distilling 20-30 g. of the sample with an excess of concen- 
trated sodium hydroxide solution from a very capacious conical flask 
fitted with a vapour-trap; the distillate is collected in Ay 10 sulphuric 
acid, and the excess titrated back with standard alkali. 

Should ammonia be the only base present, it may be determined by 
simply titrating an aqueous emulsion of the material with N/2 hydro- 
chloric acid, using methyl orange as the indicator. The amount of acid 
corresponding to ammonia, found by either method, is calculated to 
" acid value," and is subtracted from the total acid value obtained by 
direct titration ; the difference represents free acid. 

(c) Neutral Fatty Matter. — The sample is shaken up with petroleum 
spirit and N/io alcoholic sodium hydroxide (50 per cent, alcohol), and 
the neutral fat isolated as described above (p. 89). 

(d) Soap. — I. When, the soap acids present are ordinary fatty or 
naphthenic acids, sulphonated fatty acids or oxidised resin acids being 
absent, the soap content of the material can be determined as in 
ordinary lubricants (p. 88). Ammonia, if present, beside fixed alkali, 
must be determined and allowed for. 

2. Sulphonated acids or oxidised resin acids introduce complications, 
as they combine with considerably more alkali than ordinary fatty acids. 
Thus sulphonated fatty acids require one equivalent of alkali for the 
carboxyl group and a second one for the sulphonic acid group. In such 
cases the organic acid present in the form of soap is determined as 
above, and in addition the total alkali absorbed is determined gravi- 
metrically by incineration. The carbonate found by incineration is 
calculated to metal and added to the soap acid, whereby the amount of 
soap as such is arrived at. 

Exaviple : — 

Free acid found = 10 (" Acid Value " ). 

Weight of total acid, as under c = 15 g. (corresponding to " acid 
value" 30). 

Hence, weight of free acid = — = 5 g- ^i^d 

weight of soap acid = 10 g. 

Alkali found as ash, calculated to metal, =2 g. 

Hence weight of soap present approximately = 10-^2= 12 g. 

Whether soap alkali is to be determined by titration (i) or by 
incineration (2) is decided by a preliminary qualitative test of the 
isolated organic acids, 



104 LUBRICANTS 



Literature. 



Archbutt L. and Deely, R. M. — Lubrication and Lubricants, 3rd edition, 1912. 
Grossmann, J. — Die Schmiennittel, Methoden zu Hirer Untersuchung und Wert- 

bcstimmung, 1909. 
HOLDE, D. — Untersuchung der Mineralole und Fette, 1909. 
Hurst, G. H. — Lubricating Oils, Fats, and Greases, 3rd edition, revised by H. 

Leask, 191 1. 
Lewkowitsch, J. — Chemical Technology and Analysis of Oils, Fats, and Waxes, 

vol. iii., 4th edition, 1909. 
Redwood, I. I. — Lubricants, Oils, and Greases, 1898. 



OILS, FATS, AND WAXES 

By the late J. Lewkowitsch, M.A., Ph.D. English translation 
revised by the Author. 

CLASSIFICATION OF OILS, FATS, AND WAXES. 

The oils, fats, and waxes which form the raw material of the fat and 
oil industries are found ready formed in plants and animals. The oils 
and fats differ chemically from the waxes, in that the former are glyceryl 
esters of fatty acids, whereas the latter are esters derived from fatty 
acids and monohydric alcohols. On this basis it is easy to distinguish 
between oils and fats, on the one hand, and waxes, on the other hand, by 
chemical means ; namely, by the detection of glycerol. In nature 
apparently only triglycerides occur ; mono- and diglycerides are the 
result of a secondary reaction which may be regarded as a natural 
hydrolysis. The present section deals only with the triglycerides. 
The natural oils and fats represent complicated mixtures of the most 
varied triglycerides, including not only simple triglycerides containing 
a single fatty acid, but also mixed triglycerides in which the glyceryl 
radicle is combined with different fatty acids ; hence an exhaustive 
scheme of analysis similar to the systems of inorganic analysis is 
impracticable. There is, however, no necessity for such a scheme, as 
it is generally possible to indentify a given oil, fat, or wax on the basis 
of a systematic method of examination, and in addition to determine 
whether a sample is pure or adulterated ; these are the most important 
problems in their technical analysis. 

It is also possible, with the help of the methods described below, to 
identify a mixture of two or more oils or fats, and to obtain an approxi- 
mate indication as to their relative proportions. The larger the 
number of components in a mixture, the more difficult their detection 
and estimation will naturally be. If, however, the tests are applied on 
a strictly logical basis, and the methods described are combined in 
a suitable manner, it is frequently possible to ascertain, with sufficient 
accuracy for technical purposes, the composition of mixtures which 
appear at first to be hopelessly complicated. 

As glycerol is obtained as a product of saponification from all oils 
and fats, the differentiation of the glycerides must necessarily depend 
upon the differences of the several fatty acids occurring in the natural 

105 



lOG OILS, FATS, AND WAXES 

oils and fats, disregarding for the present the more intricate and 
hitherto scarcely investigated differences depending upon the isomerism 
of the mixed glycerides. Hence it follows that in addition to the 
examination of the oils and fats themselves, an investigation of the 
fatty acids is of great importance. 

In tlie case of the waxes, whose alcoholic constituents, in contra- 
distinction to glycerol, are insoluble in water, the examination of the 
alcohols is of increased importance. The alcoholic compound is spoken of 
in technical practice as " unsaponifiable matter," although this expression, 
in contrast to saponifiable matter, includes not onl)- the alcohols, but 
also (unsaponifiable) hydrocarbons, such as, mineral oils, rosin oils, tar 
oils, etc. Strictly speaking, only the fatty acids themselves are 
saponifiable, that is, capable of conversion into soaps. As, however, 
glycerol, in itself unsaponifiable, is soluble in water, in contradistinction 
to the alcohols of the waxes and to the hydrocarbons, the glycerides 
are technically considered as completely saponifiable. 

A systematic investigation would therefore comprise the examination 
of the oils, fats, and waxes of the fatty acids, and of the unsaponifiable 
matter. 



THE EXAMINATION OF OILS, FATS, AND WAXES. 

Both physical and chemical methods are employed in the examina- 
tion of natural oils and fats. 



A. — Physical Methods. 

Preliminary indications are obtained from the colour, consistency, and 
also from the smell and taste. The colour is chiefly of importance for 
the recognition of certain individual substances amongst the solid fats, 
e^., raw palm oil and aouara oil. The consistency at ordinary tempera- 
ture helps to give a ready indication as to whether a sample belongs to 
the class of liquid fats (oils) or of solid fats. Smell and taste characterise 
the oils derived from marine animals. In the case of other commercial 
oils and fats these " organoliptic " indications can only be made use of 
by experts, for they require an extensive experience which is not at 
the disposal of every technical chemist, the acquirement of which is, 
however, very desirable. In the examination of oils and fats which 
form articles of food, both the smell and taste are of very great 
importance. 

The determination of the specific gravity, melting point, solidifying 
point (especially of fatty acids), and of the refractive index is of 
primary importance. The viscosity, the optical rotation, and the 
solubility are frequently determined as subsidiary tests. 



PHYSICAL METHODS OF EXAMINATION 



107 



I. DETERMINATION OF THE SPECIFIC GRAVITY. 

The specific gravity of liquid oils and waxes is determined by the 
hydrometer, pyknometer, or the hydrostatic balance. It is advisable 
to make the determinations at the normal temperature of 15° C. (or, as 
is usual in England and America, at 15"- 5 C, corresponding to 60° F.), 
as most of the observations recorded in the literature have been made 
at this temperature, and can therefore be used for purposes of com- 
parison. However, if it is impossible to make the determination at this 
temperature, a correction of ±0-00064 per degree is applied. The 
determination is often made at higher temperatures. In such cases, 
Sprengel's pyknometer (Fig. 33) is used. The Sprengel tube is filled 
with the fat by dipping the tube b into the oil 
and sucking it up with the aid of a rubber tube 
attached to a. The tube is then suspended as 
deeply as possible in a beaker of water, which is 
heated to boiling. The oil expands in the Sprengel 
tube in the direction of least resistance towards a^ 
so that the side tube a -always remains full. If 
the meniscus of the liquid lies beyond ;;/, the 
excess is removed at a by a small roll of filter 
paper. If, on the other hand, there is too little 
oil in the tube, a drop of the oil is brought in 
contact with <7 on a glass rod, and is drawn into 
the tube by capillarity. The specific gravity of 
the substance is compared with that of water at 
the same temperature as found by determining 
the specific gravity of water under identical con- 
ditions. The temperature of the water in the 
control test must always be stated. 

The specific gravity of solid fats is usually determined at 100°, in 
the same manner as described above. In the case of beeswax, however, 
the test is generally carried out as follows : — The wax is first melted 
on a watch-glass on the water-bath and allowed to solidify gradually. 
Small pieces are then cut out of the mass, brushed with a damp brush 
to remove air bubbles, and carefully introduced into dilute alcohol with 
the aid of a pair of forceps. Water or alcohol, as the case may be, is 
then added until the wax neither floats nor sinks, but remains suspended 
in the liquid. The alcohol is filtered off, and its specific gravity 
determined ; the value obtained is, of course, identical with the specific 
gravity of the wax. 

As a rule the determination of the specific gravity gives but little 
information as to the nature of a given sample. It furnishes, however, 
indications in the case of the liquid waxes, which are characterised by a 




Fio. 33. 



108 OILS, FATS, AND WAXES 

low specific gravity, as also in the case of castor oil, the specific gravity 
of which is high. The specific gravity also frequently helps to indicate 
adulteration, or serves as a confirmation of conclusions drawn from the 
other methods detailed below. A list of the specific gravities of 
the commoner oils, fats, and waxes is given below (see Tables, pp. 146 
et seq.). 

II. DETERMINATION OF THE MELTING POINT AND THE 

SOLIDIFYING POINT. 

The fats and waxes have no sharply defined melting points, such as 
pure chemical substances exhibit when tested in capillary tubes. If 
this method be applied to fats, the melting point extends over several 
degrees, the substance first softening, then melting at the edges 
and becoming translucent, and finally melting to a clear liquid. Hence 
there is considerable uncertainty as to what temperature should be 
accepted as the melting point. Some chemists define the melting point 
as that temperature at which the fat softens so that it is driven up 
the tube by the hydrostatic pressure of the water, when immersed in 
water in a small tube open at both ends. Others, again, dip the bulb of 
a mercury thermometer into the molten fat, allow it to solidify, and 
take that temperature at which the fat softens sufficiently to drop off the 
bulb as the melting point. As several different methods are still in 
technical use, it is absolutely essential to state precisely in every 
instance the procedure by which the melting point has been 
determined. 

Further, it is to be noted that a freshly melted sample does not show 
the correct melting point, and that it is necessary to allow such 
a sample to remain at rest for twenty-four hours before determining 
the melting point. 

The following methods are still in commercial use in tendering for 
supplies of fats : — 

Pohl's method, which consists in dipping the bulb of a thermometer 
into the molten substance so that a thin layer remains on the glass. The 
thermometer is then allowed to stand for one to two days in a wide test 
tube, which is corked so that the bulb of the thermometer is at a distance 
of 1-25 cm. from the bottom. The test tube is then heated in 
a water-bath, and the temperature at which the fat collects as a drop at 
the bottom of the bulb is taken as the melting point.^ L. Ubbelohde has 
increased the accuracy of the method by the introduction of a special 
thermometer (see " Lubricants," Fig. 32, p. 99), to the bottom of which 
a small glass vessel containing a hole is attached. The temperature at 
which the fat softens may be recognised by the formation of a drop, 
and the melting point is taken as the temperature at which it drops off. 

' Cf. R. Mcldrum, C/iem. Xncs, 1913, 108, 199, 233. 



THE REFRACTIVE INDEX 109 

Hitherto this method has not met with general acceptance, at any rate 
in this country, and the somewhat high cost of the apparatus forms a 
drawback to its introduction. 

A better method is that introduced by Boverton Redwood, which 
gives good results with sufficiently solid fats, when applied in the 
following manner : — A lump of the fat, not recently melted, is brought on 
to a bright surface of mercury, and slowly warmed in a dish over 
a beaker. The temperature at which the fat spreads over the mercury 
is taken as the melting point. 

The determination of the melting point is still frequently made 
in a capillary tube. As the fat passes through successive phases 
of softening, translucency, and finally of melting, it is usual to state the 
initial and final point of the melting. 

The determination of the melting point is only of importance in the 
case of " winter oils " and chocolate fats. 

The solidifying point of the fatty acids, or, as it is technically called, 
the "titre," is of far greater importance. For this purpose the fatty 
acids must first be isolated by the method described in the following 
Section (p. 174). 

III. DETERMINATION OF THE REFRACTIVE INDEX. 

The determination of the refractive index, which has been 
very considerably simplified by the introduction of the oleo-refractometer 
of Amagat and Jean, and especially by the construction of Zeiss' butyro- 
refractometer, forms one of the simplest and most important preliminary 
tests for oils and fats, especially of butter fat and of lard. Formerly 
unjustified objections were raised by various workers against the 
reliability of the refractometric method ; ;more recently, however, on 
account of the ease and rapidity of measurement by the butyro- 
refractometer, this mistrust has given place to undue optimism, 
as is evidenced by many recent publications, so that a warning in 
this connection is necessary. In the testing of butter fat especially, 
conclusions have been drawn which are unsubstantiated. With 
the help of the butyro-refractometer it is possible to tell at a 
glance whether a butter fat has been grossly adulterated ; but when 
the readings differ but slightly from the " normal " value, or even when 
" normal figures " are obtained, this is no proof of the purity of a butter 
fat, for it is an easy matter to prepare mixtures of margarine and cocoa- 
nut oil, which give the same refractive index as does normal butter fat. 
Even when abnormal values are obtained, this does not afford certain 
proof of adulteration, for there are certain kinds of butter which give 
refractometric figures deviating considerably from the normal ones. 
The refractometric test must, therefore, be considered only as a 



110 



OILS, FATS, AND WAXES 



preliminary test, although one of great importance. It would be quite 
unjustifiable to attempt to identify oils and fats by this method alone. 

As a rule, there e.vists a certain correlation between the refractive 
index and the iodine value, as may be gathered from the Tables given 
on pp. 146 ct see]., in which the refractive indices of the most important 
oils and fats arc collated. 



The Butyro-Refractometer. 
The essential parts of this instrument (Fig. 34) are two glass prisms 




Fio. S4. 



contained in the two metal cases A and B. One face of each of 
the prisms is exposed. The case B can be rotated on the axis C, so 
that the two exposed faces of the prisms can be brought into contact 
and removed from one another. The two metal cases are hollow ; 
if warm water is allowed to flow through them, the glass prisms are 
heated. A metal jacket which holds a thermometer M is attached to the 
inner case, the mercury bulb reaching into the case. K is a telescope 



THE BUTYRO-REFRACTOMETER 



111 



containing a scale divided from i-ioo, and J a mirror for illuminating 
the prisms and scale. 

The heating arrangement shown in Fig. 35 is used to warm 
the water. The boiler, heated by the gas burner B^ is fitted with 
a thermometer T^ and a thermo-regulator S^. The neck A^ is connected 
by a glass and rubber tube with a vessel C^, placed above the heater 
and charged with cold water ; the rubber tube carries a screw clip E^. 
Before heating the boiler, water is allowed to flow into it by opening 
the clip Ep The clip is then closed, and the rubber tube G^ is connected 
to the gas supply and the flame lit at B^. By turning the screw Pj^, the 
flow of gas to the burner Bj is regulated once 
for all, so that a constant temperature of the 
water in the boiler is maintained. 

Directions for fitting up the Refractometer 
in connection with the Heating Apparatus. — 
The instrument is placed in a convenient posi- 
tion, and is illuminated either by daylight or by 
lamplight. 

The rubber tube attached to the prism jacket 
of the refractometer (Fig: 34) is connected to 
the nozzle D^ of the heating bath ; at the same 
time a rubber tube is attached to the outlet of 
the metal jacket of the refractometer and is led 
to an empty vessel placed at a lower level, or to 
a sink. The screw clip E^ is then opened, and 
water is allowed to flow from the vessel C^ 
(F^ig- 35) into the heating bath. This causes 
warm water to flow through the outlet tube of 
the bath and so through the rubber tube D 
into the prism jacket B, thence through the 
rubber tube shown in Fig. 34 into the other 
prism jacket, through the metal jacket of the 
thermometer, and so through the outlet and rubber tube. The two 
glass prisms and the bulb of the thermometer are thus heated by the 
warm water. 

The flow of water through the heater is regulated by the screw clip, 
so that the water trickles out in a slow stream, and the thermometer 
indicates the desired temperature (as a rule, 40°). 

Application of the Oil or Fat to the surface of the Prism, and 
Reading of the Refractometer Value. — The prism jacket of the 
refractometer is opened by turning the milled head F (Fig. 34) about 
half a revolution to the right until it releases the catch, whereupon one 
half of the jacket may be turned round the other. The support H 
holds B in the position shown in Fig. 34. The instrument is moved by 




Fig. 35. 



112 



OILS, FATS, AND WAXES 



the left hand into such a position that the exposed surface of the prism 
B is approximately horizontal, and three drops of the filtered oil (or 
molten fat) are applied to the surface with the aid of a small glass rod, 
and spread with the rod, so that the whole surface is covered. The 
prism jacket is then closed by bringing B and A together, and turning 
the milled head to the left into its original position. The mirror is then 
brought into such a position that the border line between the bright 
and the dark portions of the field is seen distinctly. The upper part of 
the telescope, which can be drawn out, is focussed so that the scale 
appears quite distinct. 

Three minutes are allowed to elapse before reading off the scale 
division at which the border line between the bright and dark portions 
of the field lies ; fractions of the marked divisions are estimated by 
the eye. The thermometer is read immediately after taking the 
reading. 

The refractometer reading.s, if not taken at 40 , must be corrected to 
this temperature by adding 0-55 division to the reading for every degree 
of temperature above 40 ; conversely, for every degree below 40', 0-55 
division must be subtracted. 

Cleaning of the Refractometer.— After every experiment, the 
surfaces of the prisms and their metal fittings must be carefully cleaned 
with soft linen or soft filter paper, moistened with ether. 

Testing the Adjustment of the Refractometer Scale. — The 
refractometer itself should be tested from time to time with the normal 
liquid supplied with the apparatus. 

For this purpose the thermometer is fitted into position, water at 
the ordinary temperature allowed to flow through the prism jacket (no 
heating being necessary in this case), and the refractometer number of 
the normal liquid determined, the thermometer reading being taken at 
the same time. If the scale is correctly adjusted, the following refracto- 
meter numbers should be obtained at different temperatures : — 



Temperature. 


Divisions on scale. 


Temperature. 


Divisions on scale. 


25° C. 


71-2 


16° C. 


76-7 


24° 


71-8 


15° 


77-3 


23° 


72-4 


14° 


77-9 


22° 


73-0 


13° 


78-6 


21° 


73-6 


12° 


79-2 


20° 


74-3 


11° 


79-8 


19° 


74-9 


10" 


80-4 


18° 


75-5 


9° 


81-0 


17° 


76-1 


8° 


81-6 



If necessary, the scale must be adjusted with the key supplied with 
the instrument. 



VISCOSITY. OPTICAL ROTATION 



113 



The divisions of the scale correspond to the following refractive 
indices : — 



Divisions on scale. 


Refractive index. 


Dift'erence. 





1-4220 


0-0080 


10 


1-4300 


0-0077 


20 


1-4377 


0-0075 


30 


1-4452 


0-0072 


40 


1-4524 


0-0069 


50 


1-4593 


0-0066 


60 


1-4659 


0-0064 


70 


1-4723 


0-0060 


80 


1-4783 


0-0057 


90 


1-4840 


0-0055 


100 


1-4895 





Intermediate values are easily obtained by interpolation. 
The refractometers of the newest construction are provided with a 
micrometer screw, which permits of a more accurate estimation of the 



tenths of a degree. 



IV. THE DETERMINATION OF THE VISCOSITY. 

This is determined in one of the known forms of viscometer, the 
Redwood's viscometer being in general use in England, that of 
Saybolt in the United States, and that of Engler in Germany. These 
apparatus and the method of testing are fully described in the section 
on " Lubricants," pp. 66 and 68. This test is of importance only for 
oils which are used for lubricating purposes, e.g., rape oil and blown oils. 

V. DETERMINATION OF THE SOLUBILITY. 

This test is of secondary importance, as almost all fats are readily 
soluble in the common solvents. Castor oil alone forms an exception, 
being readily soluble in alcohol and sparingly so in petroleum hydro- 
carbons. This abnormal behaviour may be used to identify castor oil, 
and to distinguish it from other oils. 



VI. OPTICAL ROTATION. 

This has up to recently been seldom used in technical analysis, and 
was chiefly applied for the detection of rosin oils in fatty oils. Recently, 
however, this test has gained in importance, since the oils of the 
chaulmoogra group can be identified with the aid of the polariscope. 
In this manner the poisonous "Cardamom oil" (which the author first 
identified as chaulmoogra oil) can be recognised in margarines. 
Ill H 



114 OIL, FATS, AND WAXES 

B. — Chemical Methods. 

The chief chemical methods which are used in technical anal}'sis 
consist in the determination of certain values depending upon the 
nature of the fatty acids contained in the oils, fats, and waxes. As 
these figures are a measure of the quantity of different fatty acids or 
groups of fatty acids present, without, however, showing their absolute 
quantit)', these methods are appropriately termed "quantitative 
reactions." 

Besides these quantitative reactions, a number of other tests are 
available which may conveniently be grouped together as "qualitative 
methods." 

I. QUANTITATIVE METHODS. 

The values which are obtained by quantitative methods may be 
divided into two classes.^ 

(a) Characteristics, that is, numbers which determine the nature of 
an oil, fat, or wax, and may therefore serve for the identification of a 
given specimen. 

(b) Variables, that is, numbers which serve to determine the quality 
of a product, as these numbers depend upon the method of purification 
of the raw product, the age, rancidity, and other features. 

The acetyl value takes up an intermediate position, as it may 
sometimes be regarded as a characteristic and sometimes as a 
variable. 

(a) Characteristics. 

The following characteristics, which are given in the order of their 
relative importance, will be considered : — 

1. Saponification Value. 

2. Iodine Value. 

3. Reichert (Reichert-Meissl, or Reichert-VVollny) Value. 

I. Determination of the Saponification Value. 

The saponification value (Kottstorfer Value) indicates the number 
of milligrams of potassium hydroxide required for the saponification of 
I g. of a fat or wax. 

The saponification value is determined as follows: — 1-5-2-0 g, of the 
filtered fat or wax are weighed into a 150-200 c.c. flask (of good glass), 
and 25 c.c. of an approximately A^J2 alcoholic solution of potassium 
hydroxide are added. The alkali is best measured out from a pipette, 

' The expression "constant" origin.illy used in tlie older editions of Lewkowitsch's Chemical 
Technology and Analysts of Oils, Fats, and Waxes, may be advantageously replaced by "character- 
istics," as the former expression has been taken by many chemists in far too literal a sense. 



SAPONIFICATION VALUE 115 

which is always allowed to run out in exactly the same manner — both 
in the experiment proper and in the control test. The flask is attached 
to a reflux condenser or a simple glass tube and heated either on a water- 
bath, or over a small flame, so that the alcohol simmers gently. The 
flask is agitated from time to time, as long as any oil layer is visible 
at the bottom. After half an hour the saponification is almost invariably 
complete; only in the case of waxes {cf. p. 184) is it necessary to use 
strong alcohol and to boil briskly for at least an hour over a free 
flame. (The stronger the alcohol used for the preparation of the 
alcoholic potash, the more quickly the saponification proceeds. It is 
inadvisable to use alcohol of less than 96 per cent, strength.) i c.c. of 
a I per cent, alcoholic solution of phenolphthalein is then added, and 
the excess of alkali is titrated back with N\2 hydrochloric acid. 

A blank test is conducted in exactly the same way with 25 c.c. of 
the alcoholic potassium hydroxide solution. The difference of the 
amounts of acid used in the two experiments corresponds to the 
potassium hydroxide that has combined with the fatty acids. 

Example. — 1-6775 g. of lard were saponified with 25 cc. of an 
alcoholic potash solution, which corresponded to 24-6 c.c. of 7V/2 hydro- 
chloric acid (i c.c.-=o-o5t5i g. KOH). For the back-titration 12-95 c.c. 
of A72 hydrochloric acid were required. Hence, the amount of alkali 
used in combining with the fatty acids is 24-60- 1 2-95 = 1 1-65 c.c. 

This corresponds to U:^!^':^^^ = 32678 mg. KOH. 

Hence i g. of fat requires ^^ryr = 194-8 mg. KOH. 
The saponification value is therefore 194-8. 

The "cold saponification" suggested by R. Henriques ^ has no 
advantage over the above method, except in testing india rubber 
substitutes. 

The saponification values of most oils and fats lie in the neighbour- 
hood of 195, and the mean molecular weight of their fatty acids 
{cf. p. 131) is therefore approximately 276. The oils of the rape oil 
group are, however, distinguished by a lower saponification value, 
namely, about 175, as these oils contain considerable quantities of 
erucic acid of molecular weight 338. On the other hand, oils and fats 
containing considerable quantities of volatile fatty acids have a higher 
saponification value than 195. Thus, the saponification value of butter 
fat is 227. Fats containing much myristin or laurin have still higher 
numbers ; thus the saponification values of the fats of the cocoa-nut oil 
rise as high as 240-260. 

The saponification values of the waxes are far lower than those of 

1 Z. angew. Chem., 1895, 7, 721 ; 1S96, 8, 221 ; /. Soc. C/iein. hid., 1896, 15, 299, 476. 



116 OILS, FATS, AND WAXES 

the oils and fats, and are for the most part between 80 and 136. It is 
therefore possible to distinguish between the waxes (liquid and solid), 
the oils of the rape oil group, butter fat, and the oils of the cocoa-nut 
oil group by the determination of the saponification value alone. This 
holds, of course, only on the assumption that the samples under 
examination contain only negligible amounts of unsaponifiable oils, 
as the latter obviously reduce the saponification value. 

The influence of free fatty acids in a fat on the saponification value 
has been investigated by the author.^ 

2. Determination of the Iodine Value, 

The iodine value indicates the amount of iodine chloride, expressed 
in per cent of iodine, which the fat or wax is capable of absorbing. 
The iodine value is a measure of the unsaturated fatty acids, as these 
acids, both in the free state and also when combined with glycerol, 
absorb one molecule of iodine chloride, corresponding to two atoms of 
iodine, for each pair of doubly linked carbon atoms. 

The determination of the iodine value was introduced into fat 
analysis by A. von Hubl,and is carried out, either in the form originally 
proposed by him, or as modified by J. Wijs, On the basis of many 
years' experience, the latter is to be recommended as the more rapid 
and reliable method. As, however, the Wijs method has not yet met 
with the general acceptance which it undoubtedly deserves, both 
methods will be described. 

Hiibl's Method. — The quantities of oil or fat taken for the test are 
as follows: — Drying oils and fish oils, o-i5-o-i8 g. ; semi-drying oils, 
0-2-0-3 g. ; non-drying oils, 0-3-0-4 g. ; solid fats, o- 8-1 -o g. The oil is 
best weighed in a small weighing bottle, the cork of which is fitted with 
a small pipette, so that a certain number of drops of the oil or molten 
fat can be withdrawn with the help of a rubber tube fixed to the 
pipette. With a little practice the weight can be estimated to within 
a few centigrams by the number of drops. The weighed quantity is 
introduced into a well-stoppered flask of 500-800 c.c. capacity, 10 c.c. 
of carbon tetrachloride (or chloroform) added, and the substance is 
brought into solution, if necessary, by gentle warming ; 25 c.c. of an 
iodine chloride solution are then introduced by means of a pipette, this 
solution being prepared as follows : — Two solutions are made up, one 
of 25 g. of pure iodine in 500 c.c. of 95 per cent, alcohol ; and the other 
of 30 g. of mercuric chloride in the same quantity of alcohol ; these 
solutions arc kept separate. The quantit)' necessary for an experiment 
is made up twenty-four hours before use by mixing equal volumes of the 
two solutions. The mixture must not be used at once, as the iodine 
chloride solution alters its titre rapidly immediately after its prepara- 

' Chemical Technology and Analysis of Oils ^ Fats, and Waxes, vol. i., p. 385. 



IODINE VALUE 117 

tion ; the titre alters gradually even after twenty-four hours' standing, 
but remains sufficiently constant during the experiment. 

In order to avoid any loss of iodine by evaporation, it is advisable 
to moisten the glass stopper of the flask with a concentrated solution of 
potassium iodide. A clear solution should be obtained on gently 
agitating the flask ; if it is not clear, more carbon tetrachloride (or 
chloroform) must be added. The flask is then allowed to stand, 
protected from the light. At the same time a blank experiment is 
made, in which exactly the same quantity of carbon tetrachloride (or 
chloroform) and iodine chloride are brought together ; this solution 
serves to determine the titre. After about two hours the solution must 
still have a deep brown colour, otherwise the quantity of iodine is 
insufficient, and a further quantity of 25 c.c. of the iodine chloride 
solution must be added. The absorption of the bulk of the iodine 
chloride takes place during the first two hours ; after this time it 
becomes more sluggish. It must not, however, be considered as com- 
plete before about six to eight hours in the case of solid fats and non- 
drying oils, or twelve to eighteen hours in the case of drying oils and 
fish oils. For semi-drying oils eight to ten hours suffice. 

After the necessary time has elapsed, 20 c.c. of a 10 per cent, 
solution of potassium iodide are added, and, after shaking, 400 c.c. of 
water. If a red precipitate of mercuric iodide separates, more potassium 
iodide solution must be added. The excess of free iodine is then 
titrated back by the addition of Nj 10 sodium thiosulphate, the titre of 
which has been accurately determined with potassium bichromate. 
The contents of the flask are gently rotated during the titration, so that 
the free iodine which is dissolved in the carbon tetrachloride (or chloro- 
form) may pass into the aqueous solution. When the colour, which was 
originally deep brown, has become pale, a few drops of starch solution 
are added and the titration completed. Tlie iodine in the blank test is 
determined in exactly the same manner. The difference between the 
two results corresponds to the quantity of iodine chloride absorbed, and 
is calculated to per cent, of iodine. 

The potassium bichromate solution used for fixing the strength 
of the thiosulphate solution is made up by dissolving 3-8657 g. of 
bichromate in 1000 c.c. of water; i c.c. of this solution is =o-oi g. I. 
10 c.c. of a 10 per cent, potassium iodide solution are placed in a 
stoppered bottle, 5 c.c. of hydrochloric acid added, 20 c.c. of the 
bichromate solution then run in from a burette, and the liberated iodine 
titrated with the thiosulphate solution. 

To save time in the calculations, the author has prepared a Table in 

0'2 

which the logarithms of the quotients t-. 7~. are given.^ 

c.c. thiosulphate 

^ J. Lewkowitsch, Laboratory Compa?tion to the Fats ajid Oils Industries, Table II, p. 28. 



118 OILS, FATS, AND WAXES 

Example— oil<^\ g. of lard were treated with 25 c.c. of iodine 
chloride, which required in a blank test 60-9 c.c. of thiosulphate solution, 
1 6-45 c.c. of which were equivalent to o-2 ^. of iodine. For titrating 
back the excess of iodine 396 c.c. of thiosulphate solution were required. 
Hence the iodine absorbed corresponds to 609- 396 = 21-3 c.c. thio- 
sulphate solution. Since 16-45 c.c of thiosulphate are equivalent to 

0-2 e. iodine, the iodine absorbed is " r" . — = 0-25S9 ?• Hence 
° 1 0-45 



r, , , , 0-2589 X 100 ^ o • A- 

<j. of lard absorb — ^^ — = 76-28 g. lodme. 

0-3394 

The iodine value of the sample is therefore 76-28. 



For a discussion of the theory of the complicated chemical 
changes occurring in Hiibl's iodine chloride .solution, cf. Lewkowitsch, 
Chemical Technology and Analysis of Oils, Fats, and Waxes, vol. i., 
pp. 398 et seq. 

Wijs' Method. — Solutions of 7-9 g. iodine trichloride and Z-y g. 
iodine respectively, in glacial acetic acid, are made up by warming on 
the water-bath, taking care that no moisture from the air be absorbed. 
The glacial acetic acid must be pure (it must give no green tinge when 
warmed with potassium bichromate and concentrated sulphuric acid). 
The two solutions are poured into a litre flask and made up to i litre 
with glacial acetic acid. 

In a laboratory in which many iodine values are determined, it will 
be found cheaper to dissolve 13 g. of iodine in i litre of glacial acetic acid, 
to ascertain the exact titre of the solution by means of thiosulphate, and 
then to pass washed and dried chlorine gas into the solution until the 
titre has exactly doubled. With a little practice, the exact point 
at which the iodine has just become converted to iodine chloride 
can be judged by the change in colour of the solution. 

The iodine value is determined exacth- in the manner described 
above for Hiibl's method. Carbon tetrachloride is used as the solvent 
instead of chloroform, as the latter frequently contains alcohol. Wijs' 
solution can, however, be used immediately after preparation, and 
remains unaltered for months, so that it is not necessary to carry 
out a blank test in every case. The solution also offers the great 
advantage that solid fats and non-drying oils require only half an 
hour, semi-drying oils one hour, and drying oils two to six hours 
(according to the iodine absorption) for the completion of the 
reaction. 

The iodine value is one of the most important data in the analysis 
of fats, as all oils, fats, and waxes within the groups given in the Tables 
below can be arranged in a natural system according to the magnitude 
of the iodine values (see Tables, pp. 146 et seq.). 



REICHERT VALUE 



119 



3. Determination of the Reichert (Reichert-MeissI, or Reichert- 
Wollny) Value. 

The Reichert (Reichert-MeissI, or Reichert-Wolhiy) value indicates 
the number of cubic centimetres of A^/io potassium hydroxide necessary 
for the neutralisation of that portion of the soluble volatile fatty acids 
which is obtained from 2-5 g. (or 5 g.) of a fat by the Reichert distillation 
process. 

E. Reichert, who introduced this method into the analysis of fats, 
used 2- 5 g. of fat for the estimation ; it is, however, now more usual to 
take 5 g, of fat, as recommended by E. Meissl and R. Wollny. The 
Reichert-MeissI or Reichert- Wollny value is not, however, simply twice 
that of the Reichert value, as is frequently assumed. It is always 
necessary to state precisely how the distillation has been carried out. 




Fig. 36. 



as the results differ somewhat according to the method adopted. As a 
rule, however, the Reichert-MeissI or Reichert-Wollny value may be 
taken as approximately 2-2 times the Reichert value. 

The following details of the method have been agreed upon by a 
Committee of the Government Laboratory and the Society of Public 
Analysts.^ 

The Reichert- Wolhiy Method. — The apparatus used is shown in 
Fig. 36. The fat is filtered and 5 g. are introduced into a 300 c.c. flask. 
A sodium hydroxide solution is made up by dissolving pure 98 per 
cent, sodium hydroxide in an equal quantity of water. This solution 
must be preserved from the action of atmospheric carbon dioxide as 
completely as possible. 2 c.c. of this solution and 10 c.c. of alcohol 
(about 92 per cent, strength) are added to the fat, and the mixture is 

^ Analyst^ 1900, 25, 309. 



120 OILS, FATS, AND WAXES 

heated under a reflux condenser for about fifteen minutes on a boiling 
water-bath. The alcohol is then distilled off on the water-bath until a 
dry soap is left. This is dissolved in lOO c.c. of hot water, which 
has been previously boiled for at least ten minutes, the flask being 
heated until all has passed into solution. Then 40 c.c. oi N/i sulphuric 
acid, and three or four pieces of pumice, about the size of peas, are 
added, and the flask at once connected by means of the bulb-tube to the 
condenser. The flask is heated on a sheet of asbestos 12 cm. in 
diameter, and having a hole in its centre 5 cm. in diameter. The flame 
is at first turned low to melt the fatty acids. W^hen these have become 
clear, the flame is turned up, and the solution distilled so that exactly 
no c.c. pass into the measuring flask in thirty (twenty-eight to thirty- 
two) minutes. The distillate is shaken, 100 c.c. are filtered off, 0-5 c.c. 
of an alcoholic solution of phenolphthalein (i g. in 100 c.c.) added to the 
filtrate, and this then titrated with A710 alkali or baryta. 

A blank experiment is made in exactly the same manner with the 
same reagents. The A710 alkali used in this test must not exceed 0-3 c.c. 
The amount of alkali used in the blank experiment is subtracted from 
that used in the actual experiment, and the difference is multiplied 
by I -I. 

The number thus found is the Reichert-Wollny value ; the Reichert- 
Meissl value is almost identical with this. The Reichert-Meissl value 
of the majority of oils and fats, namely, those whose saponification value 
is below 200, is less than 0-5. All oils and fats whose saponification 
values exceed 200 have Reichert-Wollny values above i-o. 

The Reichert-Meissl value furnishes important information as to the 
nature of an oil or fat. Thus, butter fat is characterised by a Reichert- 
Wollny value of about 27-29, the fats of the cocoa-nut oil group have a 
Reichert-Wollny value of 5-8, and finally, dolphin oil and porpoise oil 
have Reichert-Meissl values of 47-120 (cf. Tables on pp. 146 et scq.). 

The Leffmann-Beam saponification method is generally used when it 
is desired to determine at the same time the titration number of 
the insoluble volatile fatty acids (see p. 156). 

A solution of 100 g. of sodium hydroxide in 100 c.c. of water is made 
up, and 20 c.c. of this solution are mixed with 180 c.c. of pure concen- 
trated gl)-cerol. 20 c.c. of this glycerol alkali solution and 5 g. of the 
filtered fat arc placed in an Erlenmeyer flask, and heated for two or three 
minutes over a free flame until the water is driven off, and the liquid is 
clear. For the rest, the procedure is the same as described above. 

Determination of the Acetyl Value. 

The acetyl value indicates the number of milligrams of potassium 
hydroxide required for the neutralisation of the acetic acid obtained 
on saponifying i g. of the acetylated fat or wax. 



ACETYL VALUE 121 

The determination of the acetyl value of oils and fats is based on 
the principle that glycerides containing hydroxylated fatty acids take 
up an acetyl group for each hydroxyl group on heating with acetic 
anhydride. The chemical change consists, therefore, in the replacement 
of the hydrogen atom of the alcoholic hydroxyl group or groups by the 
radicle of acetic acid. 

The determination of the acetyl value is carried out by the method 
given by the author^ as follows : — lo g. of oil are heated for one or two 
hours under a reflux condenser with double the quantity of acetic 
anhydride. The solution is then poured into a beaker of looo c.c. 
capacity, mixed with 500-600 c.c. of boiling water, and heated for half 
an hour, a slow current of carbon dioxide being at the same time passed 
through the liquid ; this prevents the liquid from bumping. The 
mixture is allowed to separate into two layers, the water layer syphoned 
off, and the oily layer boiled out three times successively with water. 
The last traces of acetic acid are removed in this way, the liquid 
being tested with litmus paper. If the heating be unduly prolonged, 
the acet}'l derivative is hydrolysed to an appreciable extent, and the 
acetyl value found is too low. The acetylated product is then filtered 
through a dry filter paper in a drying oven. 

About 5 g. of the acetyl derivative are then saponified by boiling 
with an accurately measured quantity of alcoholic potassium hydroxide, 
as described under the determination of the saponification value 
(p. 1 14). The alcohol is evaporated off, the soap dissolved in water and 
a quantity of Nji sulphuric acid added, equivalent to the alcoholic 
potash used. On careful warming, the fatty acids separate as an oily 
layer, which is then filtered off and washed with boiling water until the 
washings are no longer acid. The filtrate is then titrated with Njio 
alkali. The number of cubic centimetres required is multiplied by 56-1 
and divided by the weight of substance. Triglycerides which contain 
no hydroxy-acids and no soluble fatty acids give no acetyl value. Tri- 
glycerides of hydroxylated fatty acids give the values required by 
theory, hence the acetyl value is in this case a characteristic of the fat. 

Triglycerides which contain hydroxy-acids, and at the same time 
also soluble fatty acids, give acetyl values which include also the soluble 
acids. In order to obtain the true acetyl value, the quantity of alkali 
required to neutralise the soluble acids (which must be determined by a 
blank experiment) must be subtracted from the apparent acetyl value, as 
determined above. In this case also the acetyl value is a characteristic. 

In the natural oils and fats, however, which contain varying 
quantities of free fatty acids, and hence also varying quantities of 
monoglycerides and diglycerides, the acetyl value is a variable, as its 
value depends not only on the presence of hydroxy-acids, but also on 

' J. Soc. Chem. Inci., 1897, 16, 503. 



1 9 

1 Ml ^ 



OILS, FATS, AND WAXES 



the amount of monoglycerides and diglycerides present. The natural 
oils and fats contain also small quantities of free alcohols, which also 
contribute in some degree to the acetyl value. As oxidised acids (see 
p. 139) also give acetyl values, the acetyl value is very probably a 
measure of the rancidity of an oil or fat.^ 

(b) Variables. 

The following variables are considered here : — 

1. The Acid Value. 

2. The content of Glycerol. 

3. The Unsaponifiable Matter. 

I. Determination of the Acid Value. 

The acid value indicates the number of milligrams of potassium 
hydroxide required to neutralise the free fatty acids in i g. of fat or wax. 

The acid value is thus a measure of the free fatty acids in a fat or 
wax. For the determination an accurately weighed quantity — as a rule 
not less than 5 g. — is mixed with neutral (or neutralised) alcohol, or 
dissolved in a mixture of alcohol and ether, and titrated with aqueous 
or alcoholic potassium hydroxide, with phenolphthalein as indicator. 

The acid value is calculated as shown in the following example: — 
Example. — For the neutralisation of the free fatty acids in 6- 508 g. 
of tallow, 3-5 c.c. of A710 potassium hydroxide were required, corres- 
ponding to 3-5 X 5-61 mg. KOH. The quantity required for i g. is 

r 3-5X5-6I 
therefore -^ — =7; — = 3-01. 
6-508 ^ 

The acid value is frequently expressed in per cent, of oleic acid ; it 
is then sufficiently accurate to give half the acid value as the percentage 
of free fatty acid. 

Older methods of calculating take as units, in some cases, the 
quantity of acid calculated as sulphuric acid ; in others, the "degrees of 
acidity," that is, the number of cubic centimetres of normal alkali required 
to neutralise 100 g. of fat. The following Table facilitates the conversion 
of one term into anv other : — 



Acid value. 


Oleic acid. 


SO3. 


Degrees of acidity. 




Per cent. 


Per cent. 




1-0 


0-5036 


0-0714 


1-7857 


rgs.'i? 


1-0 


0-142 


3-5458 


14-0 


7-042 


1-0 


25-0 


0-5G 


0-2817 


0-04 


1-0 



' Cf. Lewkowitsch, Chemical Technology and Analysis of Ois, Fats, and Waxes, vol. i, 
P- 435- 



CONTENT OF GLYCEROL 123 

In the literature on fats the acid value is much too frequently con- 
sidered as a "characteristic" (constant). This is entirely misleading, 
as the acid values of the natural oils and fats, and perhaps also of the 
waxes, are dependent upon the purity of the sample, the age, the degree 
to which hydrolysis has occurred, and any oxidation which has taken 
place. The acid value may therefore vary from o to the maximum of 
about 195 for any fat; the latter value would correspond to 100 per 
cent, of free fatty acids, which number the author has, in fact, found in 
the case of a very old palm oil. 

The designation of the "ether value" or "ester value" (that is, the 
difference between the saponification value and the acid value) as a 
"characteristic " (constant) is equally misleading. 

2. Determination of the content of Glycerol, 

If the natural oils and fats were neutral triglycerides, the quantity of 
glycerol could be calculated from the saponification value according to 
the following equation : — 

C3H,(OR)3 .+ 3KOH = C3H3O3 + 3KOR. 

In this case the glycerol content would form a "characteristic." As, 
however, the majority of the natural oils and fats contain free fatty 
acids, and hence in all probability mono- and diglycerides, the glycerol 
content varies, and must therefore be considered as a "variable." 

The determination of glycerol in oils and fats is best effected 
indirectly by the acetin method, as the glycerol obtained by the saponi- 
fication of a fat invariably contains organic impurities, which give 
abnormally high values when the glycerol is determined by oxidation 
(by permanganate or bichromate). 

For the acetin method, a crude glycerin must first be prepared. 
For this purpose, 20 g. of the sample are saponified with alcoholic 
potash as described under the determination of the saponification value 
(p. 1 14), and the alcohol evaporated off on the water-bath. The 
resulting soap is dissolved in water, and decomposed by sulphuric acid, 
so that the precipitated fatty acids may be filtered off. The filtrate is 
treated with excess of barium carbonate, and evaporated on the water- 
bath until the bulk of the water is driven off. The residue is then 
extracted with a mixture of ether and alcohol (i : 3), the bulk of the 
ether-alcohol evaporated off by careful heating on the water-bath, and 
the residue dried in a desiccator and weighed. It is not necessary to 
dry to constant weight, as the glycerol in the crude product is accurately 
determined by the acetin method. 

This method depends upon the complete conversion of glycerol to 
triacetin on boiling with acetic anhydride, and the subsequent hydrolysis 
of the product with sodium hydroxide. The acetic acid thus formed is 



124 OILS, FATS, AND WAXES 

a measure of the amount of glycerol. The crude gl)xerol obtained as 
above is heated to boiling with 8-10 c.c. of acetic anhydride and 4 g. of 
sodium acetate, in a round-bottomed flask of about 100 c.c. capacity, 
under a reflux condenser, for one and a half hours. It is then allowed 
to cool a little, the condenser rinsed out with hot water, and the acetin 
brought into solution by gentle agitation. If necessary, the contents 
of the flask may be gently heated, but must not be boiled, as triacctin 
is volatile with steam. The liquid is filtered from a flocculent pre- 
cipitate which separates into a wide-necked flask of about 500-600 c.c, 
capacity, and allowed to cool to the ordinary temperature. Phcnol- 
phthalein is added, and the acetic acid neutralised with sodium hydroxide 
of about 5 per cent, strength. During the addition of the alkali 
the flask must be continually shaken round so that there is never 
any local excess of alkali. The neutral point is reached when the pale 
yellow colour just becomes reddish-yellow. The addition of so much 
alkali that a red colour is formed must be avoided. If an excess has 
been accidentally added, so that the neutral point has been over- 
stepped, the experiment must be rejected. With practice the colour 
change can be easily observed. Exactly 25 c.c. of sodium hydroxide 
solution of about 10 per cent, strength are then added, the strength of 
this solution being determined by a blank experiment, and the solution 
is boiled for a quarter of an hour. The free alkali in both experiments 
is then titrated back with Nji hydrochloric acid ; that is, the total alkali 
in the blank experiment, and the excess of alkali in the experiment 
proper. The difference gives the amount of alkali required for tht 
saponification of the triacetin. 

Example. — 1-5064 g. crude glycerin weighed out. 25 c.c. sodium 
hydroxide solution required in the blank experiment, 53-0 c.c. Nil 
hydrochloric acid, and in the actual experiment, 14-7 c.c. Nji hydro- 
chloric acid for the back-titration. Hence, 530— i47 = 38-3 c.c. were 
required for the saponification of the triacetin. Since 1 c.c. A71 

hydrochloric acid corresponds to — ^ = 0-03067 g. glycerol, the crude 

glycerin contained 0-03067 x 38-3 = 1-1746 g. glycerol (= 77-97 per 
cent, glycerol). The 20 g. fat originally taken for the test contained, 
therefore, 1-1746 g. glycerol, or 5-87 per cent. 

A direct method for the determination of glycerol, proposed 
by A. Shukoff and P. Schestakoff,i by extraction of a solution containing 
at least 40 per cent., has not yet met with general acceptance on 
account of its tediousness. 

3. Determination of the Unsaponifiable Matter. 

The term "unsaponifiable matter" comprises all those sub.stances 

* Z. angew. Chem., 1905, 18, 294 ; J. Soc. Clum. Iml.y 1905, 24, 294. 



UNSAPONIFIABLE MATTER 125 

which are insoluble in water, or which do not form soluble soaps with 
caustic alkalis. The natural oils and fats always contain small 
quantities of unsaponifiable matter. 

The unsaponifiable matter is separated as such, and to this end the 
fat must first be saponified. It is convenient to combine the determina- 
tion of the unsaponifiable matter with that of the saponification value; 
it must, however, be borne in mind, that in view of the very small 
quantity of unsaponifiable matter, it is necessary to take at least 5 g. for 
the test The procedure is as follows : — 5 g. of the sample are saponified 
with 25 c.c. of alcoholic sodium hydroxide, containing 80 g. of sodium 
hydroxide per litre, by heating on a water-bath in a porcelain dish, and 
evaporated to dryness. The soap is dissolved in 50 c.c. of hot water, 
transferred to a separating funnel of about 200 c.c. capacity, and the 
residual contents of the dish rinsed into the separator with 20-30 c.c. of 
water. After cooling, about 50 c.c. of ether are added, and the whole 
is well shaken. If the layers do not separate readily, a little alcohol or 
concentrated sodium hydroxide is added. The clear soap solution is 
run off into a second separating funnel and shaken out again with 
ether. The ethereal extracts are combined, washed with a little water, 
and transferred to a weighed flask. The ether is evaporated off on 
the water-bath, the residue dried at 100°, and weighed. In the case of 
most oils and fats, ether is preferable to petroleum spirit for the 
extraction. 

This method is not suitable for determining the unsaponifiable 
matter in beeswax, carnauba wax, and other solid waxes, as not only 
are the alcohols derived from these esters sparingly soluble in cold 
ether, but also the alkali salts of the fatty acids do not dissolve easily 
in water, nor even in dilute alcohol. In such cases it is advisable 
to neutralise the soap solutions, after adding phenolphthaiein, with acetic 
acid, and to precipitate with either barium chloride or lead acetate. 
The precipitate is then washed, dried, mixed with sand in a mortar, 
and extracted in a Soxhlet apparatus with petroleum spirit boiling 
below 80°. 

A characteristic component of the unsaponifiable matter of vegetable 
oils and fats is sitosterol or other closely allied phytosterols ; the 
unsaponifiable residue of animal oils and fats, on the other hand, contains 
cholesterol. A further examination of the unsaponifiable matter 
is imperative when it is necessary to distinguish between vegetable and 
animal fats (see p. 1 39). 

II. QUALITATIVE METHODS. 

The following qualitative methods of examination frequently yield 
important clues for the detection and valuation of individual oils and 
fats, and must be used to supplement the quantitative reactions, when 



126 OILS, FATS, AND WAXES 

the latter fail to give definite indications. A number of qualitative 
reactions have become superfluous since the method of determining the 
iodine value has come into use, e.g., the elaidine test, the sulphur 
chloride test, and also the thermal reactions with sulphuric acid, 
bromine, and sulphur chloride. Only the following methods need 
therefore be described : — 

1. Oxygen absorption. 

2. Bromide test. 

3. Colour reactions. 

I. Oxygen Absorption. 

The absorption of atmospheric oxygen is of great importance 
in judging the danger of spontaneous combustion when oils are 
distributed in a finely divided condition on organic fibres {cf. "Wool 
oils," p. 160) ; it is generally determined in the case of drying oils. The 
methods used for this purpose are mostly " practical " tests ; these are 
described in the following Section (p. 165). 

If a convenient method for the determination of the total oxygen 
absorbed during drying were available, it would be possible to obtain a 
quantitative expression of the drying properties, or as it might be 
termed, of the " oxygen value." Quantitative determinations have in 
the past been made, but in a very unsystematic fashion, such important 
factors as the temperature, the influence of light, the moisture of the air, 
the thickness of the layer, and the age of the oil having been more or 

less ignored. 

As the drying of an oil requires a somewhat lengthy period of time, 
attempts have been made to accelerate the absorption of oxygen, by 
adding finely divided lead (" molecular " lead) (A. Livache^), or finely 
divided copper (Hubl, Lipperf-). The lead powder is obtained by 
precipitating a lead salt by means of zinc. The precipitate is washed 
with water, alcohol, and ether in rapid succession, and finally dried in a 
vacuum. Livache's test is carried out as follows : — i g. of the lead 
powder is spread out in a thin layer on a fairly large watch-glass, and 
0-6-07 g. (not more) of the oil allowed to drop on to the powder, 
care being taken to let each drop fall on to a separate place on the lead 
(or copper) powder, and not to allow the drops to run together. The 
watch-glass is then allowed to stand at the ordinary temperature in the 
li'^ht. Linseed oil attains its maximum absorption in a few days, 
whereas under other conditions the same result is obtained only after a 
prolonged time. Livachc states that drying oils attain their maximum 
absorption in eighteen hours, or in some cases after three days, whereas 
non-drying oils show an increa.se of weight only after four to five days. 

1 CompUs rend., 1886, 102, I167 ; y. Soc. CJieiii. IiuL, 1886, 4, 494. 
- Uum. Revue, 1 899, p. 67. 



OXYGEN ABSORPTION 127 

Weger ^ rejects Livache's method and suggests the use of larger 
quantities of lead, 2 g. of lead being used for each o-2 g. of oil. But 
even under these conditions the results are unsatisfactory. 

M. Weger- and also W. Lippert^ have undertaken a systematic 
study of the drying properties of oils, the oils being exposed to the air 
in extremely thin layers on glass plates. It was shown that the glass 
plates could not be replaced by any other lighter material ; plates of 
celluloid, gelatin, and even ebonite were found altogether unsuitable ; 
mica plates were satisfactory but are too easily broken, whilst thin 
metal plates are too easily deformed. The following precautions are 
necessary in the experiments : — The glass plate must be quite clean 
(free from dust), and the oil must be very carefully spread out in a 
uniform thin layer. If the layer is uneven in thickness, it is possible 
for an increase of weight to be taking place in one place, whilst a 
decrease is occurring at another. A series of tests showed that, the 
thinner the layer of oil, the more rapidly the oxygen is absorbed at 
the commencement of the experiment, whilst an equilibrium sets in 
after about twenty-four hours. The thicker the layer, the more slowly 
the weight increases; but if the layer is altogether too thin, unreliable 
results are obtained. The best conditions for the absorption of oxygen 
seem to be reached when the layer of oil is so thin that 0-0005 g- cover 
I sq. cm. of the glass plate. 

This method is obviously very tedious, and depends upon the 
accuracy with which decimilligrams can be weighed ; moreover, it 
does not yield absolute data, and can only be used as a guide in 
comparative experiments. If it is only a question of distinguishing 
between drying, semi-drying, and non-drying oils, the determination of 
the iodine value (p. 1 16) is not only more easily carried out, but has also 
the advantage of giving quantitative results. At the same time, it must 
be emphasised that the iodine value is not an absolute measure of 
the drying properties ; for fish oils and liver oils add just as much 
iodine as the best drying oils, and yet absorb much less oxygen. 
Furthermore, the former are distinguished essentially from the latter 
in that they do not form a skin as linseed oil does. Fish oils and liver 
oils are, however, best distinguished from the drying oils by the bromide 
test (^/ p. 137). 

2. The Bromide Test. 

On the basis of Hazura's work on the action of bromine on 
unsaturated acids, O. Hehner and C. Mitchell ^ proposed the following 

1 Chem. Revue, 1898, p. 246. 

2 C/iem. Rev Fett-lnd., 1897, 4, 313, 327 ; /. Soc. Chem. Ind., 1898, 17, 257, 360. 

3 Chem. Rev. Feit-fnd., 1899, 6, 65 ; /. Soc. Chem. hid., 1899, 18, 693. 
* Analyst, 1898, 23, 313- 



128 



OILS, FATS, AND WAXES 



test, which is described with certain modifications which have been 
worked out in the author's laboratory : — 1-2 g. of the oil are dissolved 
in 40 c.c. of ether with the addition of a few cubic centimetres of glacial 
acetic acid. The solution is cooled in a corked flask to 5°, and bromine 
then added, drop by drop, from a drawn-out tube, until the brown 
colour no longer disappears. After standing for three hours at 5°, the 
liquid is filtered through a pleated filter and washed four times 
successively with 10 c.c. of ether cooled to 0°. The residue is finally 
dried in a water-oven to constant weight. In the following Table a 
number of results obtained by this test are collated, of which some are 
given by Hehner and Mitchell, and the remainder obtained by the 
author and his assistants. Walker and Warburton. 

The bromide test is especially adapted to the testing of drying oils 
and fish oils. It is still better to apply it to the fatty acids, as it is 
possible in this way to distinguish between vegetable dr)'ing oils and 
fish oils (cf. p. 137). 

Table 21. 
Yield of Hexabromides from Glycerides. 



Oil. 


Yield of bromides 
insoluble in ether. 


Observer. 






Per cent. 




Linseed oil (iodine value 


181) . 


23-14; 23-52 


Walker and Warburton 


II ( 11 


186-4) 


24-17 


Lewkowitsch 


11 C. 11 


190-4) 


37-72 


11 


i> • • 


• • 


23-86 to 25-8 


Hehner and Mitchell 


Tung oil . 









II 


„ (sample 1) . 









Walker and Warburton 


I, ( „ 2). 






0-38; 0-39 


i> 


Candle nut oil . 






8-21 ; 7-28 


II 


Walnut oil 






1-42; 1-9 


Hehner and Mitchell 


Poppy seed oil . 









M 


Soya bean oil . 






3-73 


Lewkowitsch 


Maize oil . 









Hehner and Mitchell 


Cotton seed oil . 









11 


11 • • 









Lewkowitsch 


Brazil nut oil . 









Hehner and Mitchell 


Almond oil 









11 


Olive oil . 









II 


Japan fish oil . 






21-14 ; 22-07 


Walker and Warburton 


F'ish oil deodorised , 






49-01 ; 52-28 


II 


Cod liver oil 






42-9 


Hehner and Mitchell 


11 ■ " 






35-33; 33-76 


Walker and Warburton 


,, (Newfoundl 


and) 




32-68 ; 30-62 


11 


Shark liver oil . 






22 


Hehner and Mitcliell 


II * • 






21 •2-2; 19-08 


Walker and Warburton 


Seal oil . 






27-54 ; 27-92 


11 


Whale oil 






25 


Hehner and Mitchell 


(old) . . 






15-54; 16-14 


Walker and Warburton 


„ (fresh) 






20-1 ; 22-6 


Lewkowitsch 


Sperm oil. 






2-61 ; 2-42 


Walker and W^arburton 


11 • • • 






3-72; 3-69 


11 






after standing for 








48 hours 





COLOUR REACTIONS 129 



3. Colour Reactions. 

Of the almost innumerable colour reactions which have been 
proposed, and are still being proposed, only the following, as the 
author has shown by extensive tests, can be recommended as trust- 
worthy and of practical value.^ 

(a) H. Baudouvi's Test. — This reaction, originally introduced by 
Camoin, is used for the detection of sesame oil, certain components of 
which give a characteristic red colour with hydrochloric acid and cane 
sugar. As cane sugar is converted by hydrochloric acid into levulose 
and furfural, Villavecchia and Fabris have suggested the following 
method of carrying out the test : — A solution of i vol. of colourless 
furfural in lOO vols, of absolute alcohol is made up, and to o-i c.c. of this 
solution, 10 c.c. of the sample, and 10 c.c. of hydrochloric acid of sp. gr. 
1-19 are added, the whole well shaken and allowed to settle. If the 
sample contains even less than i per cent, of sesame oil, the lower 
aqueous layer shows a distinct crimson-red colour. In case colouring 
matters are present in the fat, which give a coloration with hydro- 
chloric acid alone, these should be removed first by shaking the sample 
with concentrated hydrochloric acid. The only objection to this treat- 
ment is that it is sometimes necessary to repeat the shaking so many 
times that the chromogenetic substance in sesame oil is also destroyed. 

(b) Halphen's Test. — This indicates cotton seed oil. Equal volumes 
of the sample, amyl alcohol, and carbon bisulphide containing i per 
cent, of flowers of sulphur in solution, are heated for fifteen to thirty 
minutes in a test tube in a water-bath or salt water-bath for fifteen to 
thirty minutes. In presence of cotton seed oil a characteristic red 
colour is obtained. The value of this test must not be overestimated 
since on the one hand cotton seed oil, which has been previously heated 
to i8o°-25o'', fails to give the reaction, and on the other hand when cattle 
are fed with cotton seed oil cakes or cotton seeds, the chromogenetic 
substance passes into the milk fat ; it also passes into lard, when hogs 
have been fed with cotton seed or cotton seed oil cakes. It must also 
be noted that kapok oil and baobab oil also give this reaction. Recently 
E. Gastaldi- has shown that only commercial amyl alcohol produces 
the colour, which is therefore produced by impurities in the amyl 
alcohol. Pyridine and allied bases give the colour reaction very 
distinctly. 

(c) Becchi's Test (Silver nitrate test). — This test for cotton seed oil 
is less reliable than Halphen's. It is most trustworthy when carried 
out as proposed by Tortelli and Ruggeri : 5 g. of the sample are 

^ J. Soc. Chem. Ind.^ 1894, 13, 617 ; also Lewkowitsch, Chemical Technology and Analysis of 
Oils, Fats, and Waxes, \o\. i., pp. 398 et seq. 

^ Ami. Lah. Gabelle, 1912, 6, 601 ; J. Soc. Chem. hid., 1912, 31, 934. 

Ill I 



130 OILS, FATS, AND WAXES 

saponified and the liquid fatt\' acids are isolated {cf. p. 134); these are 
dissolved in 10 c.c. of 95 per cent, alcohol, i c.c. of a 5 per cent, solution 
of silver nitrate added, and the solution warmed to 70'-8o'. In presence 
of cotton seed oil, the silver nitrate is at once reduced, whereas other 
oils reduce it only after a considerable time. 

(d) The Nitric Acid Test is frequently useful as a preliminary 
indication of cotton seed oil. A few cubic centimetres of the sample 
are shaken with an equal volume of nitric acid of sp. gr. 1-375 and 
allowed to stand for some time (up to twenty-four hours). In presence 
of cotton seed oil a coffee-brown colour is observed, which is still 
produced by heated cotton seed oil and its fatty acids (which, as stated 
above, fail to give the Halphen reaction). 

The three last-mentioned colour reactions for the detection of cotton 
seed oil must be used with the greatest circumspection, and must be 
considered at the best only as confirmatory tests. 

(e) Liebcrj)iann-Sto)-ch Test. — This colour reaction is extremely 
trustworthy for the detection of rosin oils. A quantity of 1-2 c.c. of 
the sample is dissolved in acetic anhydride with moderate warming ; 
after cooling a dpop of sulphuric acid of sp. gr. i-53 (prepared by 
mixing 34-7 c.c. of concentrated sulphuric acid with 35-7 c.c. of water) 
is added. In presence of rosin acids a beautiful violet-red fugitive 
colour is obtained. Cholesterol also gives a similar colour. If the 
latter is suspected the rosin acids must be separated from the 
unsaponifiable cholesterol. The best method for the detection of 
cholesterol is described below (p. 139). 

(f) The Sulphuric Acid Test. — All the colour reactions with sulphuric 
acid given in the older literature are unreliable, with the exception of 
the reaction for the detection of liver oils. 

To carry out the test i drop of the oil is dissolved in 20 drops of 
carbon bisulphide, and a drop of concentrated sulphuric acid is added. 
If liver oils are present a violet-blue colour is produced, which quickly 
changes to red and brown. The colour seems to be produced not only 
by cholesterol but also by " lipochromes." 

C. — Examination of the Fatty Acids. 

In case the methods described above have not given sufficient 
information for the identification of a sample, the free fattv acids must 
be examined. For this purpose physical methods such as the deter- 
mination of the solidifying point (titre) {cf. the following Section, p. 174, 
and Tables, p. 146) are used, but more especially the following chemical 
methods, which are to some extent based upon the above quantitative 
reactions.^ 

^ For further methods, cf. Lewkowitsch, Chemical Technology and Analysis of Oils, Fats, and 
Waxes, vol. i., chap. viii. 



EXAMINATION OF FATTY ACIDS 131 

1. Determination of the Neutralisation Value, from which the mean 
molecular weight can be derived. 

2. Determination of Lactones (Anh)drides). 

3. Determination of Insoluble Fatty Acids. 

4. Determination of Soluble Fatty Acids. 

5. Separation of Saturated Fatty Acids from Unsaturated. 

6. Examination of the Saturated Fatty Acids. 

7. Determination of Oleic, Linolic, Linolenic, and Clupanodonic 
Acids. 

8. Determination of the "Oxidised" Fatty Acids. 

The free fatty acids are prepared as described in the following 
Section under the "determination of the titre of tallow," p. 174). 
The soluble volatile fatty acids need only be taken into consideration 
in the case of oils and fats whose saponification value exceeds 
200. 

If great accuracy is desired, the unsaponifiable matter should be 
removed with ether, before decomposing the soap solution with mineral 
acid (see p. 124). 

I. Determination of the Neutralisation Value and the 
Mean Molecular Weight. 

The neutralisation value indicates the number of milligrams of 
potassium hydroxide required to saturate i g. of the mixed fatty 
acids. 

The determination of the neutralisation value is carried out in 
exactly the same manner as described under "acid value" (p. 122), but 
using aqueous normal alkali. It is advisable to take at least 5 g. of 
the sample for the determination. Deductions as to the approximate 
composition of a mixture of fatty acids may be obtained from the 
following Table {cf. also the Tables given on pp. 146 et seg.). 

From the neutralisation value thus found, the mean molecular 
weight is calculated as follows : — Let M be the mean molecular weight 
of the fatty acid ; then M grams must, according to theory, be 
neutralised by 56-1 g. potassium hydroxide. If « be the number of 
grams of potassium hydroxide which have been shown by experi- 
ment to neutralise i g. of fatty acid, then the proportion M : 56-1 

= I : ;/. and hence M = . The value of fi is found by multiplying 

n 

the number of cubic centimetres of normal alkali required for i g. fatty 

acid by 00561, If this number of cubic centimetres be a then 

n = rtX 0-0561. Introducing this into the above equation : — 

T\,T 56-1 1000 

M = — ~ >- = . 

^xo-050i a 



132 



OILS, FATS, AND WAXES 



Table 22. 
Neutralisation Values of Fatty Acids. 



Aci-I. 


Formula. 


Molecular weight. 


Neutralisation 
value. 1 


Acetic .... 


C..H,0.. 


60-03 


934-5 


1 Butyric 




c^H.o.; 


88-06 


637-07 


Caproic 




CfiHrP, 


116-10 


483-22 


1 Caprylic 




C,H„P, 


144-13 


389-23 


Capric . 




CiqHoo^'o 


172-16 


325-85 


Laurie . 




CijHjjiOa 


'200-19 


280-30 


Myristic 




C]4H2f,02 


228-22 


245-81 


Palmitic 




Ci«H,.0, 


256-26 


218-90 


Stearic . 




C,,H,^0, 


284-29 


197-33 


Oleic . 




^lHri^CJ.> 


282-27 


198-74 


Linolic 




cZ^hPl 


278-24 


200-17 


' Linolenic 




CigHgoOo 


280-26 


201-62 


Clupanodonic 




^IH"-28^-2 


276-22 


203-09 


Ricinoleic 




^is^.-mOs 


298-29 


188-08 


' Arachidic 




^20"-4o'-'2 


312-32 


179-62 


Erucic . 




V-/.>> ti 42^2 


338-34 


165-81 


Cerotic 




C36HB2O2 


396-42 


141-52 


Melissic 




^30 "60^2 


452-48 


123-98 


Hydroxystearic 




CisHneO;; 


300-29 


186-81 


' Dihydroxysteaiic 




C]8H.3604 


316-29 


177-33 


Triiiydroxystearic 




^is^'se'-'s 


332-29 


168-82 


Sativic . 




CigHseOe 


348-29 


161-07 


Linusic 




CisHsfiOg 


380-29 


147-51 



2. Determination of Lactones (Anhydrides.) 

If the free fatty acids, instead of being examined for their neutralisa- 
tion values as described above, are boiled with excess of alcoholic 
potash as in the determination of the saponification value (p. 1 14), the 
same value should be obtained, or in other words, the saponification 
number of a fatty acid should be identical with its neutralisation value 
on the assumption that the amount of unsaponifiable matter is negligible. 
If, however, the fatty acids contain lactones or anhydrides, the saponifica- 
tion value will be greater than the neutralisation value. The difference 
forms a measure of the lactones or anh)'dridcs present. Its determina- 
tion is of importance in the examination of candle materials (see next 
Section, p. 173). 

3. Determination of Insoluble Fatty Acids. 

For this determination the fat is filtered, and 3-5 g. arc saponified as 
described under "saponification value" (p. 114), using, of course, a flask 
of double the capacity given above. The alcohol is then completely 
evaporated off, until the snap solution becomes thick. Then i(X)-i50c.c. 
of hot water are added, the solution acidified with dilute sulphuric acid, 
and heated until the liberated fatty acids float on the surface as a clear 



EXAMINATION OF FATTY ACIDS 133 

oily layer. The solution is next filtered through a filter paper of about 
lo cm. diameter, previously dried at lOo" and weighed, taking care first to 
fill the filter paper half full of hot water. The liquid is then brought on to 
the filter, keeping it half full throughout the operation. The fatty acids 
are washed with hot water on the filter, until a few cubic centimetres of 
the filtrate no longer redden sensitive litmus paper. In the case of 
fats of the cocoa nut oil and dika fat groups, 2 or 3 1. of water are 
sometimes necessary. On the completion of the washing the funnel and 
filter are immersed in cold water, so that the liquid in the filter and the 
water outside are at the same level. This causes most fatty acids 
to solidify. The water is allowed to drain off, the filter brought into a 
small weighed beaker and dried for two hours at 100". After weighing, 
the drying is continued for an hour, and the weighing repeated. The 
difference between the two weights does not usually exceed i mg. ; 
absolute constancy cannot be expected, as there are two sources of 
error, which, however, usually compensate one another. On the one hand 
unsaturated fatty acids become slightly oxidised, and on the other hand 
they volatilise to some extent. The fatty acids of highly unsaturated 
oils are best washed with, ether into a tared flask, and dried in a current 
of carbon dioxide or hydrogen. 

Most fats give a yield of 95 per cent. ; only those fats which have 
high Reichert values yield less than 95 per cent. It must be borne in 
mind that any unsaponifiable matter is weighed with the acids, and that 
the yield cannot therefore be identified with the percentage of fatty 
acids. In most oils and fats the proportion of unsaponifiable matter 
may, as a rule, be neglected, but in accurate analyses this must 
be determined as described on p. 124, and deducted. In the case 
of waxes, the alcohols separate out together with the fatty acids, and 
thus results exceeding 100 per cent, are obtained, 

4. Determination of Soluble Fatty Acids. 

A high Reichert- Meissl value points to the presence of considerable 
quantities of volatile fatty acids. The volatile fatty acids — comprising 
butyric, caproic, caprylic, capric, and lauric acids — are conveniently 
subdivided into soluble volatile acids and insoluble volatile acids, 
although a sharp analytical distinction between these two classes cannot 
be drawn. The Reichert- Meissl method estimates a. part of the soluble 
volatile fatty acids (almost all the butyric acid, part of the caproic, and 
a little caprylic acid). Similarly Polenske's method which is carried out 
in conjunction with the Reichert-Meissl method (see p. 156) gives 
approximatel}' the insoluble volatile acids (comprising very little butyric 
acid, a little caproic, more capr)'lic, almost all the capric and all the 
lauric acid which has passed over, together with traces of myristic acid). 
In the analysis of butter fat for the detection of fats of the cocoa nut oil 



13t OILS, FATS, AND WAXES 

group, the determination of both groups of acids and of their mean 
molecular \veiL;ht leads to important results.^ 

5. Separation of Saturated from Unsaturated Fatty Acids. 

The best method (though still an incomplete one) for this separation 
is based upon the solubility of the lead salts of unsaturated fatty acids 
in ether, in which the lead salts of the solid fatty acids are almost 
insoluble. This method is most trustworthy when carried out in the 
following manner worked out in the author's laboratory. The method 
depends upon a combination of the modifications proposed by ?iluter 
and de Koningh, and by Lane, to a method originally devised by 
Gusserow and Varrentrapp. 

From 3-4 g. of the fatty acids are neutralised in the usual manner in 
a 300 c.c. flask, with 50 c.c. of about Nj2 aqueous potassium hydroxide. 
(If the determination is started with the original fat this must be boiled 
with alcoholic potash to saponify it. After adding phenolphthalein the 
solution is rendered faintly acid with acetic acid, and finally exactly 
neutralised with alcoholic potash). The solution is made up to about 
100 c.c. with water. A solution prepared from 30 c.c. of a 10 per cent, 
solution of lead acetate and 150 c.c. of water, is then heated to boiling 
in a beaker, and poured, whilst boiling hot, into the soap solution, 
shaking continuously, so that the precipitated lead soaps ma}' deposit 
themselves on the walls of the flask. The flask is filled to the neck with 
hot water and allowed to cool. After the liquid has become clear it is • 
poured off or filtered if necessary. The lead soaps are carefully washed 
with hot water. It is advisable to cool the hot solutions before filtering, 
thus causing the cooled lead soaps to adhere to the sides of the flask. 
The last traces of water are removed b\' means of a small roll of filter 
paper. It is not advisable to dry the lead salts, as in the case of dr)'ing 
oils they absorb oxygen somewhat rapidly from the air. Next 150 c.c. 
of ether are added to the lead salts, the flask corked and shaken 
repeatedly, so as to disintegrate the lead salts. The flask is then 
attached to a reflux condenser, and heated on a water-bath for some 
little time with frequent shaking. The lead salts of the liquid fatty 
acids dissolve readily in the hot ether; at the same time a certain 
quantity of the saturated acids pass into solution. When the undissolved 
salts settle out at the bottom of the flask as a fine powder, the heating 
is discontinued. If all operations are conducted somewhat rapidly, and 
unnecessary exposure to the air is avoided, it is not essential to work 
in an atmos[)here of h)'drogen or carbon dioxide. The ethereal solution 
is allowed to cool, and filtered through a pleated filter covered with a 
watch glass, into a separating funnel. The undissolved salts are brought 

' C/. Lewkowitsch, Chemical 'leclinology and Analysis of Oils, Fats, and Waxes, vol. i., p. 538. 



EXAMINATION OF FATTY ACIDS 



135 



on to the filter by rinsing out the flask three or four times with ether, 
using 30-40 c.c. each time. The ethereal filtrate is then shaken with 
dilute hydrochloric acid to decompose the lead soaps. The ether 
dissolves the free fatty acids as they form, and the undissolved lead 
chloride and aqueous solution are drawn off. The ethereal solution is 
washed with water until the wash water is free from acid. P^inally the 

Table 23. 
The Iodine Value of Unsaturated Fatty Acids and their Glycerides. 











Iodine value of 


Acid. 


Formula. 


Iodine value 
of 


















fatty af-id. 


Mono- 


Di- 


Tri- 








glyceride. 


glyceride. 


glyceride. 


Tiglic 


C5H8O2 


253-68 


145-79 


198-18 


225-10 


*» * 




, 


CjoHmO^ 


128-88 


93-26 


112-22 


120-39 


*i • 




, 


CuHoyO., 


112-21 


85-54 


99-84 


106-26 


Hypogx'ic . 




- 












Physetoleic 




^16"30^'2 


99-84 


77-32 


89-93 


95-10 


Lycopodic . 














Oleic . 




"■ 












Elaidic 




- 


^I8'':u02 


89-92 


71-24 


81-80 


86-06 


Rapic. 




J 












Doeglic 
Jecoleic 




} 


r H r^ 


85-67 


68-54 


78-28 


82-15 


Erucic 
Brassidic 




\ 


C2.2H4.2O2 


75-02 


61-55 


69-23 


72-31 


Linolic 




J 












Tariric 
Telfairic 




C,8H,,0., 


181-14 


143-28 


164-68 


173-31 


Elseomargaric 














Linolenic . 




1 
/ 












Isolinolenic 




^18 "30^2 


273-69 


216-16 


248-65 


261-76 


J ecoric 














Clupanodonic 






18 28 2 


366-24 


289-04 


332-63 


350-23 


Isanic 




, 


^14 20^2 


461-19 


345-11 


409-12 


436-08 


Ricinoleic . 




•\ 












Isoricinoleic 
Ri(inelaidic 




^18 "34^3 


85-13 


68-17 


77-79 


81-37 


Ricinic 














Mixed Triglycerides . 


— 












Myristopalmito-olein 








... 




31 -54 


Oleodipalmitin . 










, . 








30-43 


Oleodimargirin . 








• . ■ 


,, 








29-48 


Oleopalmitostearin 






> • • 


• * • 






, , 




29-48 


Oleodistearin 


















28-55 


Elaidodistearin . 










.. 








28 -55 


Dioleostearin 






... 












57-24 



ether solution is filtered through a small pleated filter into an ordinary 
flask. In case the liquid fatty acids consist chiefly of oleic acid, the 
result.*: will be accurate enough if the ether be evaporated off on the 
water-bath, and the residue dried in a water-oven. If, however, more 
highly unsaturated acids than oleic are suspected (from linseed oil, soya- 
bean oil, maize oil, marine animal oils), the ethereal solution must be 



136 OILS, FATS, AND WAXES 

evaporated down in a current of dry hydrogen or dry carbon dioxide. 
The precipitate collected on the filter consists of the soaps of the 
saturated fatty acids ; the free acids are obtained by decomposing these 
soaps with hydrochloric acid in the manner described above. 

It must be especially emphasised that this method of separation is 
not absolutely accurate ; thus the solid fatty acids always retain 
unsaturated acids (the quantity of which can be estimated approximately 
by the iodine value). Moreover, the ethereal solution of the lead salts 
retains a certain quantity of saturated fatty acids, especially the volatile 
fatty acids. Nevertheless the method gives results which are sufficiently 
accurate for the ordinary purposes of technical analysis. It is advisable 
to estimate the iodine value of the liquid fatty acids, as this supplies 
valuable information as to the composition of the fats when the Table 
on p. 135 is taken as a guide {cf. also under No. 7, p. 137). 

6. Examination of the Saturated Fatty Acids. 

The only solid fatty acids which can at present be determined with 
sufficient accuracy are arachidic and stearic acids. 

Arachidic Acid. — The determination of this acid is necessary for 
the recognition of arachis oil in mixtures of oils containing arachis oil 
(adulterated olive oil). For the estimation, the solid fatty acids 
obtained from 10 g. of oil are dissolved in 50 c.c. of hot 90 per cent, 
alcohol. In presence of arachidic acid a cr)'stalline mass is obtained on 
cooling the alcoholic solution. This consists of "crude arachidic acid,'\ 
that is a mixture of arachidic and lignoccric acids. The crystals are 
filtered off and washed, first with a measured quantity of 90 per cent. 
alcohol, then with 70 per cent, alcohol ; the latter dissolves only traces 
of the acid. The crystals on the filter are finally washed with boiling 
absolute alcohol, and the filtrate collected in a porcelain dish or a 
flask. The alcohol is evaporated off and the dried crystals weighed. 
A correction must be made for the arachidic acid dissolved by the 90 
per cent, alcohol, taking as a basis that 100 c.c. dissolve at 15°, 0022, or 
at 20°, 0-045 g- crude arachidic acid. Finally, the melting point of the 
crude arachidic acid is determined ; this should be 'J\°-'J2°> 

Stearic Acid. — The determination of stearic acid depends upon the 
observation due to David, that alcohol saturated at 0° with pure stearic 
acid, dissolves all the lower solid fatty acids as also all the unsaturated 
acids, whereas stearic acid remains undissolved. The method may be 
applied either to the total fatty acids, or to the saturated fatty acids 
isolated as described on p. 134. It should, however, be observed that 
any arachidic acid present must be removed beforehand, as it would 

' For details and criticism of a modified method of estimation proposed by Tortelli and 
Ruggeri, cf. Lewkowitsch, Chemical Technology and Analysis of Oils ^ Fats, and Waxes, vol. ii., 

P- 253. 



SATURATED FATTY ACIDS 137 

otherwise be estimated as stearic acid. O. Hehner and C. Mitchell ^ have 
worked out a method on this basis, which is applicable in most cases, 
though, it must be pointed out, not in all. The stearic acid solution 
is prepared by dissolving 3 g. of stearic acid in lOOO c.c. of hot alcohol 
of sp. gr. 0-8183 in a stoppered flask. The flask is allowed to remain 
overnight in ice, and the mother-liquor is syphoned off, without taking 
the flask out of the ice water. This is done with the aid of a tube 
widened at the end to a small funnel which dips into the alcoholic 
solution ; the small funnel is covered with fine linen to retain the 
separated crystals of stearic acid. The filter tube is bent twice at right 
angles, and fitted to a flask so that the clear liquid may be drawn off 
quickly by means of a filter pump. 

If the fatty acids are solid, o-5-i-o g. is taken; if liquid, 5 g. This 
is weighed accurately in a flask, and treated with 100 c.c. of the above 
described stearic acid solution. The flask is allowed to stand overnight 
in ice water. On the next day the liquid is shaken, the flask being still 
in the ice water, to promote the separation of crystals, and then left in 
the ice water for another half hour. The alcoholic solution is drawn off 
as described above, and the precipitate remaining in the flask is washed 
three times successively with quantities of 10 c.c. of the alcoholic solu- 
tion cooled to 0°. Finally, the crystals of stearic acid adhering to the 
filter are washed into the flask with hot alcohol. The alcohol is 
evaporated off, the residue dried at 100" and weighed, and calculated to 
pure stearic acid. The melting point of the crystals should not be much 
below 68°- 5. A correction of 0-005 g. is applied for the stearic acid 
introduced by the alcoholic solution of stearic acid. If the melting 
point of the isolated acid is below 68^, the acid must be again subjected 
to the same treatment. 



7. Determination of Oleic, Linolic, Linolenic, and Clupanodonic 

Acids. 

From the iodine value of the liquid fatty acids, a preliminary indica- 
tion as to their nature is obtained. In the present state of our know- 
ledge, the acids which come chiefly into consideration are oleic, linolic, 
linolenic, and clupanodonic acids. If the iodine value is about 90, this 
indicates, as a rule, practically pure oleic acid ; if, however, the iodine 
value is much higher, then in the case of vegetable oils the presence of 
linolic and linolenic acids is indicated, and in the case of marine animal 
oils, the presence of clupanodonic acid is most probable. In the case of 
mixtures, the presence of all of these acids is possible. Linolenic and 
clupanodonic acids are detected by the bromide test, and are estimated 
quantitatively as follows : — 

1 Analyst, 1896, 21, ?2i 



138 



OILS, FATS, AND WAXES 



A solution of 0-3 g. of the fatty acid in glacial acetic acid is cooled 
in a corked flask to 5 . Bromine is then added, drop by drop, until the 
brown colour no longer disappears. Any evolution of h)drogen 
bromide is caused by too high a temperature. After standing for three 
hours to permit of complete absorption of the bromine, the solution is 
filtered through a pleated filter, and washed with four successive 
quantities of 10 c.c. of cold ether. The residue on the filter is dried to 
constant weight in a water-oven. The melting point of the bromide 
lies between 175 and 180 , in the case of the hexabromide of linolenic 
acid (from drying oils). If the bromide has not melted at 180 , but 
blackens at 200' or above, it consists of octobromidcs (from marine 
animal oils). If the residue be suspected to be a mixture of hexa- 
bromides and octobromidcs, these are separated by boiling the residue 
with benzene, in which the octobromidcs are insoluble ; the two are 
identified by their melting points after the removal of the benzene. 

Linolic acid may be approximately estimated in the filtrate as the 
tetrabromide by the following method given by K. Farnsteiner. The 
solution is evaporated and the residue, consisting presumably of a 
mixture of the dibromide of oleic acid and the tetrabromide of linolic 
acid, is treated with hot petroleum spirit of boiling point SS°-^7'S- ^n 
cooling, a crystalline tetrabromide of linolic acid separates out, whilst a 
liquid tetrabromide and the dibromide of oleic acid remain in solution. 
The crystals which are filtered off should melt at about 1 12°.^ 

The following Table contains a number of determinations carried out 
in the author's laboratory : — 



Fartty acids from oils. 



11 
-o 

's 

o 

X 
V 

X 



4> 

-a 

■§ 
o 

k. 

O 



'Linseed (iodine value 181) 
„ ( „ 184) 

„ ( „ 190-4) 

,, liquid acids (iodine va 
Candle nut 

Stiilingia .... 
Safflower .... 
Soya bean 

Rape .... 
'Japan fish (old samples) . 
(fresh „ ) . 
Deodorised fish 
Cod liver (Norway) . 

„ (Newfoundland) 
Shirk liver 

Seal 

Whale (old samples) 

,, (fresh samples) 
Sperm .... 



ue 208) 



Bromides insoluble in 
ether. 



Per cent. 

29-06; 29-34 

31-31 ; 30-44; 30-80 

38-1; 42-0 

34-9 

11-53; 11-23; 12-63 

25-78 

1-65; 0-65 

3 to 5 
2-4; 3-4 
23-04 ; 23-32 
44-2; 44-7 
38-42; 39-27 
29-86; 20-36 
39-1 ; 37-76 
12-68; 15 08 
19-83 ; 19-93 
12-38 ; 12-44 
22-59; 27-77 
2-05 



' For further details c/. Lewkowiisch, Chemical Technoloey and Analysis of Oils, Fats, and 
Waxes, vol. i., pp. 560 et seq. 



UNSAPONIFIABLE MATTER 139 

8. Determination of Oxidised Fatty Acids. 

The "oxidised" fattv^ acids comprise those acids which are present 
in oxidised oils and fats, and which are distinguished from other fatty 
acids by their tnsolubiHty in petroleum spirit. They are estimated 
as follows by W, Fahrion's method^:— 4-5 g. of an oxidised fat or oil 
are saponified in the usual manner with alcoholic potash. The alcohol 
is evaporated off, the soap dissolved in hot water, introduced into a 
separating funnel, and decomposed by hydrochloric acid. After cooling, 
the liquid is shaken with petroleum spirit (boiling below 80°) and then 
allowed to stand until it has completely separated into two layers. 
The insoluble oxidised fatty acids adhere to the walls of the funnel or 
form lumps under the layer of petroleum spirit. The aqueous solution 
is drawn off, the petroleum spirit layer decanted, and the oxidised 
fatty acids again well shaken with petroleum spirit to wash out all 
occluded soluble fatty acids. If the quantity of oxidised acid is 
large, it is advisable to dissolve it in potassium hydroxide solution, 
decompose the soap again with hydrochloric acid, and shake out as 
before with petroleum spirit. The residual oxidised acids are dissolved 
in warm alcohol, the solu-tion brought into a tared dish, the alcohol 
evaporated off, and the residue dried to constant weight. - 

/^.—Examination of Unsaponifiable Matter. 

The unsaponifiable matter, which is isolated in substance as 
described above (p. 124), can be further examined immediately. If 
the samples have not been adulterated with mineral oils, rosin oil, or 
tar oil, the quantity of unsaponifiable matter will be very small, as the 
unsaponifiable substances which occur naturally in oils and fats amount 
generally to less than i per cent. (^ above, p. 124). In waxes, however, 
the quantity is much greater — up to 50 per cent. The examination of 
the unsaponifiable matter may be divided into : — 

I. The examination of those unsaponifiable substances which are 
naturally present. 

II. The detection and estimation of unsaponifiable substances which 
have been added purposely. 

I. The Examination of Unsaponifiable Substances 
which are Naturally Present. 

(a) In Oils and Fats. 

The unsaponifiable matter in natural oils and fats contains chiefly 
cholesterol or phytosterol, accompanied by small quantities of hydro- 

1 Z. angew. Chem., 1898, II, 781 ; 1903, 16, 79, 1 199;/ ^oc. Chem. Ind., 1898, 17, 958 ; 

1904. 23, 26. 

- For the further examination of these acids, cf. Levvkovvitsch, Chemical Technology and 

Atialysis of Oils, Fats, and Waxes, vol. iii., p. 468. 



140 



OILS, FATS, AND WAXES 



carbons, higher aliphatic alcohols, colouring matters, resinous substances, 
and albuminous matter. Since, as shown above, "cholesterol" is 
characteristic of animal oils and fats, and " phytosterol " (mostly sito- 
sterol) is characteristic of vegetable oils and fats, the examination of 
the unsaponifiable matter supplies a means of distinguishing between 
animal and vegetable products. If the sample consist of a mixture of 
animal and vegetable fats, both alcohols will be found in the residue. 



X 





X 



a 7f c d 

Fio. 37.— Crystals of Cholesterol. 



n A 












r d /' f/ 

Fia. 38.— Crystals of Phytosterol. 



For the examination, the unsaponifiable matter is dissolved in the 
smallest possible quantity of absolute alcohol,^ and set aside to 
crystallise. If only very small quantities of colouring matter and 
resinous substances are present, well-formed crystals are generally 
obtained ; if this is not the case, the unsaponifiable matter is dissolved 
in 95 per cent, alcohol, and the colouring matter removed by treatment 
of the hot solution with animal charcoal. The filtrate is then evaporated 





Pio. 89.— Crystals from a mixture of Cholesterol and Phytosterol. 

to dryness, the residue taken up with absolute alcohol and allowed to 
crystallise. The crystals are removed from the mother-liquor and 
examined under the microscope. If either cholesterol or sitosterol 
(phytosterol) alone is present, it may frequently be recognised by its 
characteristic crystalline form, as shown in Figs. 37 and 38. If, however, 

' A. Burner, Z. Unters. A'a/ir. it. Genussvi., 1898, 8, S44 ; /• '^'"^- C/iem. hid., 1898, 
17. 954- 



UNSAPONIFIABLE MATTER 141 

cholesterol and sitosterol are present simultaneously, the microscopic 
examination yields very uncertain results. A. Bomer showed that mixed 
crystals are obtained (Fig. 39), whilst in the author's experience the 
crystallisation of mixtures of cholesterol and sitosterol frequently yields 
the separate crystals of the two alcohols side by side and not the mixed 
forms.^ 

The uncertainty of the microscopic method of examination is, 
however, obviated by the phytosterol acetate test worked out by 
Bomer.^ In this test the alcoholic solution containing the crystals 
which have separated is evaporated to dryness and heated for a short 
time over a small flame in a dish with 2-3 c.c. of acetic anhydride for 
each 100 g. of fat, the dish being covered with a watch-glass. The 
watch-glass is then removed and the excess of acetic anhydride 
evaporated off on the water-bath. The residue is then heated with the 
smallest possible quantity of absolute alcohol and set aside to crystallise. 
To avoid immediate solidification or crystallisation a few cubic centi- 
metres of alcohol are added. The crystallised acetates are collected on 
a small filter and washed with 95 per cent, alcohol. They are then 
again placed in the dish, dissolved in 5-10 c.c. of absolute alcohol, and 
again allowed to crystallise. The crystals are filtered off and their 
melting point is determined. As cholesterol acetate melts at ii4°-3- 
ii4°-8 (corn), whilst the " phytosterols " obtained from various oils and 
fats gives acetates melting between i25°-6 and 137° (corn), it is possible 
to draw a preliminary conclusion as to the presence of cholesterol or 
phytosterol alone from the melting point of the recrystallised pro- 
duct. In cases of doubt it is advisable to repeat the crystallisation 
several more times. If the melting point of the fifth crystallisation 
is still below 116", the absence of phytosterol may be considered as 
established. 

For the identification of stigmasterol and brassicasterol, and for 
the detection of traces of paraffin wax with which lard, for instance, 
may have been adulterated in order to circumvent the phytosterol 
acetate test, cf. J. Lewkowitsch, Chemical Technology and Analysis of 
Oils, Fats, and Waxes, vol. i., pp. 591 et seq. ; vol. ii., chap, xiv., 
" Lard." 

(6) In Waxes. 

As the waxes contain considerable quantities of higher alcohols 
which prevent a rapid saponification, it is advisable to saponify with 
2\N alcoholic potash under pressure, or with sodium ethylate. A 

^ Cf. also Lewkowitsch, Chemical Technology and Analysis of Oils, Fals, and Waxes, vol. i., 

P- 584. 

'^ Z. Unlers. Nahr. u. Genussm., 1901, 4, 865, 1070 ; 1902, 5, 1018 ; cf also R. H. Kerr, 
U.S. Depart, of AgriculL Bureau Animal Chem. Circular 212, loth May 1913 ; J. Soc. Chem. huL, 
1913,32, 917- 



142 OILS, FATS, AND WAXES 

systematic examination of the unsaponifiable matter from waxes is 
difficult, and is therefore seldom carried out in commercial anal\'sis.^ 

The melting point of the unsaponifiable matter ma\' furnish a rough 
guide as to the nature of the substances under investigation. The 
behaviour towards acetic anhydride permits of definite conclusions as to 
the alcoholic or hydrocarbon nature of the substance, and in certain 
cases, such as spermaceti, for the identification of the wax. For this 
purpose the mixture of unsaponifiable substances is boiled with double 
its quantity of acetic anh)'dride for a short time under a reflux condenser. 
The appearance of the hot solution is then observed. If all has passed 
into solution, aliphatic alcohols or cholesterol and " phytosterol " are 
present and have undergone acetylation. If, on the other hand, an 
undissolved oil floats on the surface of the hot acetic anhydride solution, 
paraffin wax or ceresin is present. The aliphatic alcohols generally 
remain dissolved in the acetic anhydride even after cooling. If a mass 
of crystals separates out, it may be concluded that cholesterol or " phyto- 
sterol" is present, although the presence of higher aliphatic alcohols is 
not excluded. 

A summary of those characteristics which will prove of assistance in 
the examination of the solid unsaponifiable substances is given in the 
subjoined Table (p. 143). 

2 The Detection and Determination of Admixed 
Unsaponifiable Substances. 

The presence of admixed unsaponifiable substances in oils and fats 
is generally indicated by abnormally low saponification values. Solid 
unsaponifiable substances such as paraffin wax and ceresin are identified, 
in absence of waxes, by their state of aggregation and melting point. 
As a rule, especially in liquid fats, any admixed unsaponifiable matter 
consists of liquid substances belonging to one of the three following 
groups : — 

(a) Mineral oils. 

(d) Rosin oils. 

(c) Tar oils. 

The three classes of oils are scarcely ever present simultaneously. 
It is therefore only necessary to consider the possible presence 
of mineral oil together with rosin oil, or of rosin oil together with 
tar oil. 

It should be observed that a certain percentage of mineral oil is not 
necessarily to be considered as an adulteration, as it often happens (as 
for instance in burning oils or lubricating oils) that mineral oil is 
legitimately added to fatty oils. To ascertain more closely the nature 

^ For further details, c/. Lewkowilsch, Chemical Technology and Analysis of Oils ^ fals, and 
Waxes, vol. i., chap. ix. 



UNSAPONIFIABLE SUBSTANCES 



143 






u 

(0 
0) 

■M 
U 

n{ 
u 
rt 

x: 
U 



0) 
Xi 

c 

tfl 
0) 

a 

c 

to 

XJ 

3 
CO 

3 

■ «-« 

C 

o 
a 

nJ 
(/) 

G 

a 

o 



Increase of weight on 

boiling with ai'etic 

anhydride.* 


2 

g (N>ncp?oo50ia505 c^oo •" .'P 
"Ot-_vni-(Oioooo3 ;oo ••" :io»-> 

^ i-Hi— lr-( r-Hf-*T-H "f— IF— 1 t>, '"'05 

<» 

• 

CD 


< 


a 
o 
P. 
tc 
a 


°c. 

22 to 23 

31 

65 

70 

114 

under 100 

125-6 to 137 

141 


o 

U 

c 
o 
o< 
ee 
m 


^2 

•t^O(NCD>-i>-'r-io2'f'^0.- :^CO 

•0500CO.— COCOCOtMOCOvn-, "OOIM 

r— If— If— <f— (r- II— ti-Hi— II— li— (r— r— <i< r-(F— < 

CO 2 

F-( ""^ 


c» 


<D 2 

'v. £* 

° o 

.D 


^ L/ CO OO * CO ,„ . . . 
^oooo^;^^go ;^ : i2 : i 

-1 i2 CO CD ^ *" ^ 

CO 'i' 

CO 


C 

'o 

_C 

"3 


38 to 82 

50 

59 

79 

85 

148-5 

137 to 138 

137 ., 138 

170 
25-5 to 27-5 

88 „ 90 
44-4 „ 48-9 

75 to 76 ; 65 to 66-1 
49-5 to 59-2 
46-7 ■ 

78 


c 


oroooooo 

: X E ffi K K E s: ffi "• ■ ■ ^- ■-• 

00000000 




1 






Paraffin wax, ceresin 

Cetyl alcohol . . . . 

Octodecyi alcohol 

Ccryl alcohol 

Melissyl (myricyl) alcohol . 

Cholesterol 

Isocholesterol 

Phytosterol, sitosterol 

Stigmasterol 

Alcohols from sperm oil 

„ carnaiiba wax 

,, wool wax . 

,, crude wool wax 

,, beeswax 
Hydrocarbons from beeswax 
Alcohols from spermaceti . 

,, insect wax . 



D ":!. 

a ^. 

O to 
to tfi 



Q 3 r:; 



O .— tr 
rt ^- 0:1 
-" *" o 



»-. .0 



5.$.% 



u 


T) 


c 

3 


ri 




V* 


> 




C3 

to 




C 



o3 


3 


if 


-?> 


w 


m 





m 


A 






.5 3 

tj -*^ 

.2 - 

o ^ 

c * 

• .2 5 

"" 3 .a 



(» ;3 ^ 

^ a - 

g g o 



. «« 






o .S 



•a 

c 

. 3 



O 3 






o 






3 
c 

a; 
c4 



o 



13 

.2 

s 

3 



S 2 

^ 3 

*-. ■" . rt 

O - « uj 

m J" 9 .3 

= S •* >. 

c3 - c -O 

3 -a 



o 2 fi 

^ C i-i 



^5 ^ 



1 g s 1 






Hi OILS, FATS, AND WAXES 

of the isolated unsaponifiable oil, a quantity sufficient for the examina- 
tion is prepared, and the specific gravity is first determined. As the 
mineral oils in question have a sp. gr. of 0-84-0-92, and the 
rosin oils 0-96- i-oi, whilst the tar oils have a gravity over i-oi, the 
specific gravity may give useful indications, if only one oil is present. 
If a mixture of mineral oil and rosin oil is present, the Liebermann- 
Storch reaction is the best test for the qualitative detection of rosin oil. 
In this test, 1-2 c.c. of the unsaponifiable oil are gently warmed 
v.'ith acetic anhydride in a test tube and shaken. After cooling, the 
bottom layer is removed by means of a finch- drawn out pipette, and 
the solution tested as described above (p. 130). In presence of rosin 
oil a beautiful violet fugitive colour is obtained. It must not be 
forgotten that cholesterol gives a similar colour reaction. The presence 
of rosin oil may also be ascertained by the determination of the optical 
rotation, as mineral oils rotate the plane of polarised light but little, 
whereas rosin oils show a marked optical activity. (It must not, 
however, be overlooked that the hydrocarbons obtained from the dis- 
tillation of wool fat arc also optically active, as first shown by the 
author.) 

The quantitative determination of rosin oil in mineral oil is best 
effected by Valenta's method : — 10 c.c. of glacial acetic acid dissolve 
at 50", 0-2833-0-6849 g. or 2-6-6-5 per cent, of mineral oil as compared 
with 1-7788 g. or 16-9 per cent, of rosin oil. For the determination, 2 c.c. 
of the unsaponifiable oil are mixed with 10 c.c. of glacial acetic acid in a 
test tube, which is then loosely corked and heated for five minutes in a 
water-bath with frequent shaking. The solution is then filtered through 
a moistened filter paper, and the middle portion of the filtrate collected. 
A weighed quantity of this is titrated to determine the acetic acid. 
The difference between the percentage of acid found and that originally 
taken gives the quantity of undissolved oil.^ 

If the sample consists of a mixture of mineral oil and tar oil, the 
presence of the latter is detected by treatment with nitric acid of sp. 
gr. 1-45. Tar oils cause a considerable rise of temperature, whereas 
mineral oils become only slightly warmer. 

For details of Valenta's proposal to treat the unsaponifiable oils 
with dimethyl sulphate, cf. J. Lewkowitsch, Chemical Technology and 
Analysis of Oils, Fats, a7id Waxes, vol. i., p. 61 1. 

With the aid of the subjoined Tables 25-27, which are arranged as 
far as feasible according to a natural system, it will not be difficult to 
identify a sample of oil, fat, or wax, when the above described methods 
have been applied. More complete Tables are given in the author's 
Laboratory Companion to Fats and Oils Industries. A series of examples 

> Cf. Lewkowitsch, Chemical Technology ami Analyns of Oils, Fats, ami Waxes, vol, iii., 
chap. XV. 



UNSAPONIFIABLE SUBSTANCES 145 

which may serve as a guide to the investigation of more complex 
problems, are given in vol i., chap, xi., of the author's Chemical Technology 
and Analysis of Oils, Fats, and Waxes. The special methods described 
in the following Section should also be consulted. 



Literature. 

Lewkowitsch, J. — Chemical Technology and Analysis of Oils, Fats, and Waxes, 

Vol. I., 5th edition, 1913 ; Vols. II. and III., 4th edition, 1909. 
Lewkowitsch, J. — The Laboratory Companion to Fats and Oils Industries, 1901. 



[Tables 25, 26, 27. 

HI K 



146 



OILS, FATS, AND WAXES 

Table 25— Data for the Identification 



OILS. 


Characteristics. 


Sp. gr. 




0. 

c 


I 

V 

3t 


3 
"3 

a 
•5 


^=1 


c 00 tf 
1-35 


°C. 




•c. 


'C. 


KOH. 

mg. 


Per cent. 


A-/IO KOH. 
c.c. 


Per 
cent. 


Vegetable 


Drying. 
Linseed 


15 


0-9315-0-9345 


-27 


-20 


192-195 


171-201 


* • • 


95-5 


Tung oil, Chinese^ 
(Japanese) wood* J 
Candle nut 


15 
15-5 


0-9360-0-9432 
0-9256 


below - 17 


liq. at 
-18 


193 

192-6 


150-165 
163-7 


... 


92-2 
95-5 


Hemp seed 
Walnut 
Safflower . 
Poppy seed 
Sunflower . 


15 

15 
15-5 
15 
15 


0-9255-09280 
9250-0-9260 
0-9251-0-9280 
0-9240-0 9270 
9240-0-9258 


-27 
-27-5 

-18 
- 18-5 


192-5 
195 
186-6-193-3 
195 
193-5 


148 
145 
129-8-149-9 
133-143 
119-135 


1-54 (R.-M.) 



95-4 
95-37 
95-2 
95 


Semi-Drying. 

Cotton seed group — 
Soja bean 

Cameline (German "\ 
Sesame) . J 
Pumpkin seed . 
Maize 


15 
15 

15 
15-5 


0-9242-0-9270 
0-9200-0 9260 

09237 
0-9213-09255 


-8 
-18 

-15-5 

-10 to -20 


... 


192-7 
188 

188-4 
188-193 


137-140 
135-142 

123-130 
113-125 


4-5 (R.-M.) 


95-5 

96-2 
■ 93-96 


Kapok 
Cotton seed 


18 
15 


0-9199 
0-9220-0-9250 


... 


3-4 


181 
193-195 


116 
108-110 


... 


94-9 
95-96 


Sesame 


15 


0-9230-0 9237 


-5 


... 


189-193 


103-108 


1-2 (R.-M.) 


95-7 


Beech nut 
Brazil nut 
Curcas 


15 
15 
15-5 


0-9200-0-9225 

9180-0 9185 

0-9204 


-17 

0-4 

-8 


... 


191-196 
193-4 
193-2 


104-111 
106-2 
98-110 


0-5 (R.-M.) 


95-2 
95 "3 


Croton 

Rape group — Ravison . 
Hedge mustard 
Rape (Colza) . 
Black mustard seed . 


15 

15-5 
15 

15-5 
15 


0-9500 

0-9183-0-9217 

09175 

0-9132-0-9168 

0-916-0-920 


-16 

-8 

-8 

-2 to -10 

-17 


\ 


210-215 

174-179 

174 
170-179 

174 


102-104 

101-122 
105 
94-102 
96-110 


12-13-6 
(R.-M.) 

6-3 


89-0 

95-1 
95-1 


White mustard seed . 
Radish seed 

Jamba 


15-5 
15 

15 


0-914-0 916 
0-9175 

0-9154 


-8 to -16 
-10 to 
-17-5 

-lOto-12 


... 


170-174 
173-178 

172-3 


92-97 
93-96 

95-4 


0-33 (R.-M.) 


96-2 
95-9 


No\-Drying. 

A Imond group — 
Cherry kernel . 
Apricot kernel . 
Plum kernel . 


15 

15-5 

15 


9234 

0-9195 

0-9160-0-9195 


-19 to -20 

-14 
- 5 to - 6 


... 


193-195 
192-.-. 
191-5 


110-114 

96-108 
93-3-100-3 





95-4 


Peach kernel . 


15 


0-918-09215 


below -20 


... 


192-5 


93-109 


... 


... 


Almond . 


15 


9175-0-9195 


-10 to -20 




191 


93-97 


... 


962 



* To be separated on the basis of the specilic gravities. Cf. Lewkowitsch» 



VEGETABLE OILS 



147 



of Vegetable Oils and of Animal Oils. 





Variables. 


Characteristics of fatty acids. 


Refractive 
index. 


> 

< 


1 
"3 

> 

S 
< 


> 

■< 


_2 

a . 

§•3 

a 

t3 


Sp. gr. 


1.3 

•a 3 


+3 

a 

P. 
to 

a 

1 




■is 
f' 




3 
■3 

> 

1 




> 


Butyio- 

refracto- 

meter. 


"c. 


Scale 
divisions. 


KOH. 
mg. 


Per cent. 


"C. 




r, Titre. 

C. OQ 


°C. 


KOH. 

mg. 


Total 
fatty 
acids. 


Liquid 
fatty 
acids. 


°c 


Oils. 


20 


84-90 




3-98 


0-8-8-4 


•42-1-1 


15-5 


0-9233 


13-17 


19-4 to 


17-21 


197 


179-182 


190-201 


60 


1-4546 


40 


72-5 


... 














20-6 














... 


... 


... 




7-6-12 


0-44 


... 


... 


31; 34 


37-2 


31; 
43-8 


188-8 


144-159 


... 


... 




15 


76 




9-86 


8-1 


0-76 
1-08 


*.• 


• ■> 


13 
15 


16-6 


20-21 
18-19 


. . . 


141 


... 


... 


... 


40 


64 -8 


... 


... 


• . . 


• • • 


. • • 


•.. 


16 


• . . 


16-18 


**• 


150 


167 


... 


... 


40 


65-2 




16-1 


0-33-20 


. • • 




... 


• ■ • 




... 


• • • 


. . • 








40 


63-4 


• • • 


• • • 


0-7-11 


0-43 ' 


ibo 


0-8886 


16-5 


16-2 


20-5 


199 


139 


15b 


60 


1-4506 


25 


72-2 




... 


11-2 
4-5 


0-31 
0-22 


... 


... 


18 

24 
14-13 


... 


22-24 

28 
18-20 


201-6 


124-134 

119 
136-8 


154-3 
165-4 


60 


1-4531 


25 


70-2-72-5 














24-5 




28-29 


197 
















7-5 to 


1-7-20-6 


1 •35-2-86 


... 




16-14 




18-20 


198-4 


119-5 


140-144 


... 


... 








8-75 








0-9162 


24-23 




29 


191 


108 








25 


67-6-69-4 




7-6 to 
18 





0-73-i-64 


15-5 


0-9206 to 
0-9219 


32-35 


32-35 


35-38 


202-208 


111-115 


147-151 


60 


1-4*460 


25 


68 




... 


0-23 to 
66(0 


0-95-1-32 


... 




23-5 

17 


22-9 to 
23-8 


26-32 
23-24 


200-4 


110-45 
114 


129-136 


60 


1-4461 


■ •• 








... 


... 


... 


... 


32-25 




29 


• . • 


108 


... 


. • * 


• •■ 


25 


65 




7-5 


0-7-8-5 


0-5-0-58 


... 




26-5to 


28 


27-5 to 




105-1 


■ . • 


, , 


• <M 


40 


56-5 














25-7 




30-5 












27 


77-5 




19-32 


... 


0-55 




... 


16-7 


19 


... 


201 


111-5 


... 


... 


... 


20 


73-74 






4-8-12 


1-45-1-66 


100 


0-8802 










... 


124-2 






25 


70-5-71 -5 




... 


... 


... 


... 


... 


... 


> ■ . 


. . * 




• •• 








25 


68 




14-7 


1-4-13-2 


0-58-1 


ioo 


0-8758 


16 


12-13 


16-19 


185 


99-103 


121-125 


60 


1-4991 


40 


59-5 




... 


1-36 to 
7-35 


... 


... 


... 


15-5 


... 


16 


... 


109-6 


... 


... 




40 


58-5 






5-4 


... 


... 


... 


. . . 


. t . 


15-16 


• . * 


95-3 


. . . 






40 


57-5 


... 




14-5 


... 


... 


• •• 


15-13 
16-11 

15-13 


... 


20 
19-21 

19-21 


173-9 

189 


97-1 
96-1 

109 


124-7 




... 


25 


66-6 


... 


... 


o"64 
0-55 


... 


... 


... 



15-13 


..• 


3-4 

20-22 
3-5 


194 

200-5 


103 

103 (!) 


111-5 
98-6 


... 


... 


25 


66-1-67-2 


... 


... 


... 


... 


... 


... 


... 


13 to 
13-5 


10-18 


200-9 


94-101 


101-9 




... 


25 


64-4 






1-5 








5 


10-1 to 13-14 


204 


93-96-5 


101-7 


60 


1-4461 




















11-8 












Chemical Technology and Analysis of Oils, Fals, and Waxes, vol. ii., p. 03. 



148 



OILS, FATS, AND WAXES 



Table 









Cha 


racteristics. 










it! 
a 




5 


3 




ally 
tor. 








o 


d . 




^-^ <L/ : . 


\~ d *^ 


OILS. 


Sp. gr. 


1'^ 


c 
a 
% 


- a 

c > 

a 
X! 


> 

a 

'i 


-5a « > 


s, X ce 


°C. 




'C. 


"C. 


KOH. 

mg. 


Per cent. 


N/IO KOH. 
c.c. 


Per 
cent. 


Vegetable 


Non-Drying (coni.). 


















Olive group — Arachis'^ 


15 


0-9170-0-9209 


- 3 toO 





190-196 


83-100 


... 


95-8 


(earth nut) . / 


















Hazel nut 


15 


0-9146-0-9170 


-17 




192 


83-90 


0-99 (R.-M.) 


95-6 


Olive 


15 


0-916-0-918 


-6 to 2 




185-196 


79-88 


0-3 


95 


Olive kernel . 


15 


0-9184-0-9191 






183 


87-4 






Ben .... 


15 


0-9120-0-9198 


"6" 






82 






Castor group — 


















Grape seed 


15 


0-935 


-lOto -13 




178-5 


96 


0-46 (R.-M.) 


92-13 


Castor 


15'5 


0-9600-0-9679 


-lOto - 18 




183-186 


83-86 


1-4 




Animal 


Marine Animals. 


















/^?5/2 —Menhaden 


15-5 


0-927-0-933 


-4 


... 


190-6 


139-173 


1-2 




Sardine . 


15 


09330 




... 


... 


161-193 




94-5 


Japanese sardine \ 
(Japanese fish oil) J 


15 


0-9160 


... 


20 to 


189-8-192-1 


100-164 




96-97 








22 










Herring . 


15-5 


0-9202-0-939 


... 




171-194 


123-.0-142 




95-64 


Stickleback 


• • * 


... 


... 






162-0 




95-78 


Sturgeon . 


15 


0-9236 


... 




186-3 


125-3 






Sprat 


15-5 


0-9284 














Liver — Cod 


15 


0-9210-0-9270 


to"'-10 




171-6-189 


167 




95-3 


Haddock . 


15 


0-9298 






188-8 


154-2 




93-3 


Skate 


15 


0-9307 


• > • 




185-4 


157-3 




94-7 


Tunny 


. . • 




• • ■ 




... 


155-9 




95-79 


Shark (Arctic) . 


15 


0-9163 


• •• 




161-0 


114-6 




86-9 


Coal fish . 


15 


0-925 






177-181 


137-162 




... 


Hake . 


15-5 


0-9270 














Ray. 


15-5 


0-9280 














Ling 


15 


0-9200 


... 




184-1 


132-6 






Blubber— ^tzX . 


15 


0-9155-0-9263 


- 2 to - 3 




189-196 


127-141 


07-0-22 


95-45 


Whale . 


15-5 


0-9250 


below -2 




188-0 


121-136 


0-7-2-04 


93-5 


Dolphin (body) 


15 


0-9180 


below - 3 




197-3 


99-5 


5-6 


93-07 


Dolphin (jaw) . 


• • • 


• • • 






290 


32-8 


65-92 


66-28 


Porpoise (body) 


15 


0-9258 


-16 




195 


... 


23-5 




Porpoise (jaw) 


15 


0-9258 


... 




254-272 


22-50 


47-77-65-8 


70*23 


Land Animals. 


















Sheep's foot 


15 


0-9175 


to - 15 




194-7 


74-2 






Horse's f ^ot 


If, 


0-91 3-0-927 


• • • 




195-9 


73-8-90 






Neat's foot 


1 . 


0-9H-0-916 


to - 15 


... 


194-3 


69-3-70-4 


... 


... 


Egg . 


1.') 


09144 


8 to -10 


22-25 


184-4-190-2 


68-5-81-6 


0-4-0-7 
(R.-M.) 


95-16 



VEGETABLE AND ANIMAL OILS 



149 



25 — cofttinued. 





Variables. 


Characteristics of fatty acids. 


Refractive 








0) 






•+J 


a 






index. 


0? 

■3 




"3 



3 

> 
■0 


a 


Sp. gr. 


be 

hi 

-So 


'0 

Qt 
bO 

a 


^3 
*3 > 


> 

a 


? 


Butyro- 


refracto- 
meter. 




3 



< 




eg 


■3 


^ 

^ 


•a 


l-H 


PS 


•0. 


Scale 
divisions. 


< 


< 


KOH. 

mg. 


Percent. 


°C. 




°C. 


Titre. 

'C. 


°c. 


KOH. 

mg. 


Total 
fatty 
acids. 


Liquid 
fatty 
acids. 


'C. 




Oils — con tin ued. 


25 


66-67-5 


... 


3-2 


1-2 to 
32(!) 


0-54-0-94 
0-5 


100 


0-8790 


26 
19-20 


29-2 


27-7 to 

32 
22-24 


201-6 
200-6 


96-103 
90-3 


105-128 

91-3 to 
97-6 


60 


1-4461 


25 


62-4 


... 


10-64 


1-9-50 
2-3-5 


0-46-1 


100 


0-8749 


22-17 


17-2 to 
26-4 


24-27 


193 


86-90 


95-5 to 
103-5 


60 


1-4410 










16-2 


- 






20-18 




24 


187-4 


99 








25 


78 


146-7 
to 
150 


• ' ' 


0-14 to 
14-61 


. . * 


15-5 


0-9509 


3 


•" • 


13 


192-1 


87-93 


106-9 


60 


1-4546 


Oils. 










11-6 


1-6-2-2 






















... 


... 




13-0 


4-21 
10-35 

1-8-44 
21 


0-52-0-86 
0-48-2-6 

0-99-10-7 
1-73 


... 


... 


... 


28-2 


... 


178-5 
181-5 


... 




... 


... 


25 


75 


... 


4-8 
10 -6 

li-'g 


1-25 

0-2-34 
1-26 to 


0-54-7-83 

1-1 

0-97 

1-0-1-8 

10-2 


... 




... 


18-4 to 
24-3 


2i-25 


204-207 
177-0 


130-5 to 
170 




60 


1-4521 
... 


... 


... 


... 


16-5 


1-68 

11 -0 
1-9-40 


2-23 
0-38-1-4 


... 


... 


... 


15-5 to 
15-9 


22-23 


... 
193-2 


... 








25 


70 

1 
1 

1 


... 


13-b 

22-0 


0-5-37 
5-0 


0-92-3-72 

3-7 

16-4 


100 


0-8922 


... 


23-9 

21-1 

2-86 

26-1 to 

26-5 


27-0 
... 
... 

29-8 to 
30-8 


... 


131-2 

61 -98 to 
63-26 


144-7 






25 


68-5 


... 




1-2 


1-7 


... 


... 


... 


... 


34-39 


194-9 


72-9 


... 


... 


... 



150 



OILS, FATS, AND WAXES 

Table 26. — Data for the Identification 





Characteristics. 








4^ 

a 


1 


6 

_3 




• 1 


FATS.' 




3p.gr. 




C 

43 


1> 


C3 

> 

C 




i >: ea 

2 = a 








s 


CJ 

s 


1" 


1 


-5 fc,'5 


1 11 so 

acids 

flab 


°C. 




"C. 


°c. 


KOH. 

mg. 


Per cent. 


.Y/10 KOH. 
CO. 


Per 
cent. 


Vegetable. 


















Laurel oil group — 


















Laurel oil 


15 


0-9332 


25 


32-34 


197-9 


68-80 


1-6 


. . . 


Mahua butter . 


100 
(100 = 1) 


0-8981 


19-22 


28-31 


190-194 


53-67 


0-5-0-9 
(R.-M.) 


94-82 


Mowrah seed oil 


15 


0-9175 


36 


42 


188-192 


50-62 




94-76 


Macassar oil . 


15 


0-9240 


10 


22 


221-5 


48-55 




91-5 


Shea butter (Galam^ 


15 


0-9175 


17-18 


25-3 


179-192 


56-6 




94-76 


butter) . . / 


















Palm oil . 


15 


0-921-0 -9245 


... 


27-42-5 


196-202 


51-5 


0-5 


94-97 


Nutmeg butter . 


15 


0-945-0-996 


41-42 


38-51 


154-191 


40-52 
(50-81) 


1-4-2 
(R.-M.) 


... 


Cocoa group — Mkanyi . 


15 


0-9298 


38 


40-41 


190-5 


41-9 


1-21 
(R.-M.) 


95-65 


Malabar tallow 


15 


0-9150 


30-5 


36-5 


188-7-192 


38-2 




0-2 to 

0-44 

(R.-M.) 


Cocoa butter . 


15 


0-9500-0-976 


23-21-5 


28-33 


193-55 


32-41 


0-2-0-8 
(R.-M.) 


94-59 


Chinese vegetable^ 


15 


0-9180 


27-31 


36-46 


200-3 


28-37 


.» 


"... 


tallow . . / 


















Kokum butter (Goa\ 
butter). . J 


40 


0-8952 


37-6 to 


41-42 


187-191 


33-6 


0-1-1-5 


95-1 


(15 = 1) 




37-9 








(R.-M.) 


1 


Borneo tallow . 


... 


... 


... 


35-42 


... 


(31 ?) 


... 


... 


Cocoa nut oil group — 


















Mocaya oil 






22 


24-29 


240-6 


24-63 


7-0 (R.-M.) 




Maripa 


100 
(15-5 = 1) 


0-8686 


24-25 


26-5 to 
27-0 


270-5 


17-35 


4-45 
(R.-M.) 


88-88 


Palm seed oil . 


15 
(15-5 = 1) 


0-9520 


20-5 


23-28 


242- -250 


13-14 


5-6 (R.-M.) 


87-6 to 
91-1 


Cocoa nut oil • it . 


40 
(15-5 = 1) 


0-9115 


22-14 


21-24 


246-260 


8-9-5 


7-8-4 
(R.-M.) 


88-6-90 


Myrtle wax 


15 


0-995 


39-43 


40-44 


208-7 


10-7 






Japan wax . 


15 


0-9700-0-980 


48-5-53 


50-54 


217-237-5 


4-9-8-5 


... 


90-6 


Dika oil (oba oil, wild) 


... 


0-8200 


34-8 


41-6 


. . • 


31-1 






mango oil) , / 


















Animal. 


















Drying — Polar bear . 


15 


0-9256 




. . . 


187-9 


147 




... 


Semi-drying — 


















Black cock 


15 


0-9296 


... 


... 


201-6 


121-1 


2-1 


... 


Hare 


15 


0-9349 


17-23 


35-40 


200-9 


102-2 


1-59 


95-4 


Rabbit (wild) . 


15 


0-9393 


17-22 


35-38 


199-3 


99-8 


0-7 


... 


„ (tame) . 


15 


0-9342 


22-24 


40-42 


202-6 


67-6 


2-8 


95-5 


Wild duck 


... 




15-20 


• • < 


198-5 


84-6 


1-3 


• •■ 


Tame duck 




, , , 


22-24 


36-39 




58-5 






Horse 


15 


0-9189 


43-30 


34-54 


195-197 


71-86 


0-2-0-4 


95-96 



For subsidiary groups, cj. J. Lewkowitsch, BiM. Sac. Chim., 1909, 42. (Conference : Fatty Compounds.) 



VEGETABLE AND ANIMAL FATS 



151 



of Vegetable and Animal Fats. 



Variables. 



Refractive 
index. 



Butyro- 

refracto- 

meter. 



'C. 



40 



40 



Scale 
divisions. 



52-1 



lfi: 



48-85 



40 46-47-8 



25 



40 

40 



1-4628 



36-5 

-r34 



18 



2-8 



> 

'3 
< 



a 



KOH. 

mg. 



Per 
cent. 



Characteristics of fatty acids. 



Sp. gr. 



°C. 



26-3 

34-56 
6-2 to 
35-4 
29-4 

24-200 

17-44-8 

23-3 

38 

1-1 to 

1-88 

2-2-7-5 

21 

20 



1-9 to 
8-4 

0-9 to 
12-3 

27 to 
31-2 



40 
40 
40 



49 

49 

53-7 



8-36 

5-50 

3-4-4 
7-33 

19-6 



3-12 
3-5 



5-9 

2-73 

7-2 

6-2 
1-5 

0-2-44 



100 



0-8701 



1-lto 
1-63 



100 
(15-5=^1) 



98-99 
(15 -5 ---1) 

98-99 
(15-5 = 1) 



0-8230 

0-8354 
0-8480 



~ o 

o 



38-40 
38 

40 
57-5 
54-8 

47-45 

59-4 

53-5 to 
54 

22-20 
25 

20-16 

46 

53-0 to 

56-5 



15 

15 
15 

15 



Titre. 
'C. 



15-1 



a 



40-3 45 
51-6 to 52-55 
53-2 



53-8 

35-910 
45-5 
35-9 

61-5 



48-3 

45 -2 to 
53-5 



58 

47-50 

42-5 

59 to 
61-5 
56-6 

48-50 
53-57 
60-61 



a 
o 

Mi 
"A 



KOH. 

mg. 



191-6 



205-6 






Total 
fatty 
acids. 



23-25 
... '27-5to 
28-5 
20-5 to 25 to 



25-5 

22-5 to 

25-2 

59-4 



0-9374 

0-9361 
0-9246 

0-9264 



25-28 

36-40 
35-36 

37-39 
30-31 

37-7 



28-5 
25-27 

47-5 
56-62 



190 

182-208 

198-9 

254 

258-264 

258-266 

230-9 
213-7 



30-33 

44-47 
39-41 

40-42 
36-40 



199-3 

209 
209-5 

218-1 



33-7 37 -5 to 202-6 
39-5 



81-8 

56-6 
50-58 

56-57-2 

63-3 

42-1 

33-39 
30-39 



Liquid 
fatty 
acids. 



103-2 



94-6 



12-15 

12-0 

8-4-9-3 



120 

93-3 
101-1 

64-4 
84-87 



18-6 



60 



60 
60 



1-422 



1-4310 
1-4295 



40 



40 



But'r. refr- 
36 

But'r. refr. 
36 



152 



OILS, FATS, AND WAXES 



Table 



FATS. 


Characteristics. 


Sp.gT. 


If 


a 
"3 

c. 
to 

B. 

■^ 


a 
o 

ll 

|5 

C 

•n 


6 

a 

a 
o 


v u Z 


ps 

■- =3 -J 
C, i C3 

S 3 = 

.= + = 

Ui 


-c. 




°C. 


'C. 


KOH. 

mg. 


Per cent. 


A'AO KOH. 
c.c. 


Per 
cent. 


Animal {cont.). 

Non -dry inf; — 
Horse marrow . 

Goose (domestic) 
Wild goose 

Lard 

Wild boar 

Beef marrow . 

Bone 

Beef tallow 

Mutton tallow . 

Butter 

Stag 


15 

15 
15 

15 

15 

15 

15 

15 

15 

15 

15 


0-9204-0-9221 

0-9274 
0-9158 

0-934-0-938 

0-9424 

0-9311-0-9380 

0-914-0-916 

0-943-0-952 

0-937-0-953 

0-926-0-940 

0-9670 


24-20 

18-20 
18-20 

27-1 to 
29-9 
22-23 

31-29 

15-17 

35-27 

36-41 

20-23 

39-48 


35-39 
32-34 

36-40-5 
40-44 
37-45 
21-22 
45-40 
44-45 
28-33 
49-52 


199-8 

193-1 
196 

195-4 

195-1 

199 

190-9 

193-2-200 

192-195-2 

227 

199-9 


79-1 

67-71 
99-6 

50-70 

76-6 

55-4 

46-55-8 

38-46 

35-46 

26-38 

20-5-25-7 


1 

0-98 
0-2-0-3 
(R.-M.) 

0-68 
1-1 

0-25 

12-5-15-2 

1-66 


95 
93-96 

95-6 

95-5 

86-5 to 
89-8 



Table 27. — Data for the 





Characteristics. 










s 




... 








c 


t 


_o 


a 
■3 


t(R. 
hert 
t.-M 

e. 


waxks. 




Sp. gr. 


■So 


s 


05 













= A 




> 


^ 


•3=J ? > 








eg 






~3 



2 t:'s 


"0. 




°c. 


°c. 


KOH. 


Percent. 


A'/IO KOH. 












mg. 




c.c. 


Liquid — 














Sperm oil . 


15 


0-8799-0-8835 


... 


... 


125-2-132-6 


81-90 


1-3 


Bottlenose oil . 


15 


0-8764 






123-135-9 


67-82-1 


1-4 


Vegetable — 
















Carnaiiba . 


15 


0-990-0-999 


80-81 


85-86 


79-95 


13-5 




Animal — 
















Wool (wool fat) 


17 


0-9413-0-9449 


30-30-2 


31-35 


102-4 


17-1-28-9 




Bees. 


15 


0-964-0-970 


60-5-62-8 


61-5-64-4 


90-98 


7-9-11 


0-34-0-54 


Spermaceti 


15 


0-90r.-0-960 


42-47 


42-i9 


123-135 






Insect (Chinese) 


15 


0-926-0-970 


80-5-81 


80-5-83 


80-5-93 


... 


... 



VEGETABLE AND ANIMAL FATS. WAXES 



153 



26 — continued. 





Variables. 


Characteristics of fatty acidi). 


Refractive 
index. 




3 


05 






bO 


a 
'0 


.2 


a 




<o 




. 


"5 


.^fe 






Ba 


0. 


2 3 


C" 




s A 




3 




§"S 


Sp. 


gr- 




to 


'3'c3 


a 




Sg 


Butyro- 


« 




0.5 








^ 


i^> 








refracto- 




< 


tn 






03 


© 


a 


-> 




tf 


meter. 


< 




H) 








a 


i5 








^0, 


Scale 


KOH. 


ivr 


°C. 




°C. 


Titre. 


°c. 


KOII. 


Total 
fatty 


Liquid 
fatty 









divisions. 




mg. 


cent. 








u. 




nig. 


acids. 


acids. 






... 




... 


1 




15 


0-9182to 
0-9289 


36-34 


• . . 


42-44 


210-8to 
217-6 


71 -8 to 
72-2 






... 


40 


50-50-5 




0-59 




15 


0-9257 


31-32 


• • • 


38-40 


202-4 


65-3 


. . . 




... 


... 


... 


... 


0-86 




15 


0-9251 


33-34 


... 


34-40 


196-4 


65-1 
[ 


92 -i* 


60 


l-i395 


40 


48-6 to 
51-2 


2-6 
... 


0-54 to 

1-28 

2-6 


0-23 


99 
15 


0-8445 
0-9333 


39 

32-5 to 
33-5 


41-42 


43-44 
39-40 


201-8 
203-6 


64 \ 
81-2 


90-1 06t 


22 


Oil refr. 
-30 




... 


4-2 


1-6 


... 


15 


0-9300 to 
0-9399 


37-9 to 
38 




44-46 


204-5 


55-5 




... 


... 


... 


... 


11-3 


29-6-53 


0-5 to 
1-8 


• 


... 


28 


... 


30 


200 


55-7 to 
57-4 


... 


... 


... 


40 


49 


2-7to 
8-6 


3-5-50 




100 
(100^1) 


0-8698 


... 


37-9to 
46-2 


43-44 


197-2 


41-3 


92-4 


60 


1-4375 


... 


... 


... 


1-7-14 


... 


... 


... 


41 


40-15 
to 48-2 


49-50 


210 


34-8 


92-7 


60 


1-4374 


40 


41-42 


1-9 to 
8'6 


0-45 to 
35-38 


... 


37-75 
a5-5 = l) 


0-9075 


33-38 


... 


38-40 


210-220 


28-31 


... 


60 


1-437 


40 


44-5 


... 


3-5 


... 


15 


0-9685 


46-48 




50-52 


201-3 


23-6 




... 


... 



* European lard. 



t American lard. 





Variables. 


Characteristics of fatty acids. 


Refractive index. 


a 
> 



< 


Acid value. 


Fatly acids. 


Sp. gr. 


Solidifying 
poiut. 


so 
a 


4^ 

t-l 

a 

"3 



"o 

s 

5 


3 

■3 
2 




Butyro- 
refractometer. 


'C. 


Scale 
divisions. 


KOH. 

mg. 


Per 

cent. 


°C. 




^C. 


Titre. 
°C. 


'C. 


Per cent. 


40 


46-2 


4-5-6-4 




60-64 


15-5 


0-899 


16-1 


11-1-11-9 


13-3 


281-294 


83-2-85-6 


... 




4-1-6-4 


... 


61-65 


... 


... 


10 


8-3-8-6 


10-3-10-8 


... 


82-7 


... 


• •« 


55-24 


4-7 


... 




... 


... 


... 




... 


... 






23-3 




59-8 






40 




41-8 


327-5 


17 


62 


29-5-30 


15-24 
2-63 


16-8-21-2 


... 




... 


... 


... 


... 


... 


... 



SPECIAL METHODS OF ANALYSIS EMPLOYED 
IX THE OIL AND FAT INDUSTRIES 







By the late J. Lewkowitsch, M..\,, Ph.D. English translation 
revised by the Author. 

A.— OIL SEED, OIL CAKES, CRUDE FATS, ETC. 

The raw materials of the oil and fat industries in which the content of 
fat is to be determined are subdivided as finely as possible, and 
extracted with ether, petroleum spirit, or other such solvents. The dis- 
integration of the hard oil seeds may be effected by pounding in a 
porcelain mortar ; in this case, it is necessary to rinse out the mortar 
with the solvent to avoid losing any fat which has been pressed out. 
Oil seeds may also be ground in an ordinary coffee mill, but in this case 
it is impossible to avoid loss of oil. M. Lehmann ^ has constructed a 

grinding mill of such small dimensions that 
->,^ after grinding the sample the whole mill may 
/ \ be put into the extractor, together with the 
ground material. If the substances contain 
a considerable amount of moisture, the 
sample should be dried in an air-oven previ- 
ously to extraction, provided that this can be 
done without detriment to the fat ; but if any 
oxidation or loss of volatile ingredients be 
feared, the complete extraction of moist sub- 
stances is effected by using petroleum spirit 
(boiling completely below So"). Ethyl ether, 
carbon bisulphide, or chloroform maybe u.sed 
only for dry substances. The choice of solvent is not always im- 
material ; carbon bisulphide, as a rule, extracts more foreign matter 
than either ether or petroleum spirit. 

Of the numerous forms of extraction apparatus that have been 
proposed, that of Soxhlet (Fig. 40) is the most generally employed. A 
wei-T-hed quantity (20-50 g.) of substance is introduced into a " thimble " 
of filter paper (either bought ready-made or prepared by rolling filter 
paper round a cylindrical piece of wood). The tube B is then attached 
to a flask of 100-200 c.c. capacity, and the solvent added at A, until it 

1 C/iem. Zei/., 1 894, 18, 412. 
154 



V^" 



Fig. 40. 




OIL SEED, OIL CAKES, CRUDE FATS, ETC. 155 

overflows the syphon. After adding a little more solvent, A is attached 
to a reflux condenser and the flask heated on a water-bath. 

In using this form of extractor, it is always a matter of doubt when 
the extraction is complete, and it is therefore generally carried on 
longer than is necessary, with consequent loss of time and solvent. 
For this reason a modified form of Soxhlet's apparatus proposed by the 
author,^ and shown in Fig. 41, may be used with advantage ; after 
certain intervals of time a sample is drawn off into a watch-glass, and 
evaporated down to see if any residue of fat remains. 

When the extraction is complete, the heating is discontinued, the 
solvent distilled off, and the residue weighed. As ethyl ether extracts 
from moist substances not only considerable quantities of water but also 
non-fatty substances, it is advisable, when using ether, to take up the 
residual fat with petroleum spirit, after distilling off the ether. 

The drying may be done by laying the flask in a drying oven heated 
to 100''- 105^, and turning it round occasionally. When all droplets of 
water have disappeared, the drying may be considered complete. As a 
check, the substance is dried for another half an hour, and weighed 
again. In the case of drying oils, the flask is heated to ioo°-i05° in an 
oil-bath, and a slow current of carbon dioxide or hydrogen is passed 
over the heated fat. The nature of the extracted fat is determined by 
the methods described in the foregoing Section on " Oils, Fats, and 
Waxes." In the case of oil seeds and oil cakes, a careful microscopic 
examination gives useful information as to their source, purity, etc. For 
further details of this subject, special treatises must be consulted, such 
as J. Konig's Untersuchung landwirtscJiaftlicJi und gewerblicJi wichtiger 
Stoffe, pp. 244 and 278. 

^.—EDIBLE OILS AND FATS. 

The examination of these products is carried out by the methods 
described in the previous Section. Most frequently it is required to 
detect cotton-seed oil, sesame oil, and arachis oil in table oils, sold 
under the name of olive oil. The determination of the acid value is of 
importance, although it is not always safe to condemn a sample, the 
acid value of which is somewhat high (over 2), on this test alone. The 
taste is rather to be regarded as the determining factor. This Section 
is restricted to the examination of the following- edible fats : — 



't> 



I. Butter. 

The methods of examination to be described are concerned only 
with butter fat. The butter fat is prepared by melting the sample 
and pouring off the clear molten fat through a dry pleated filter. 

1 J. Chem. Soc.^ 1889, 55, 359. 



156 



ANALYSIS IN OIL AND FAT INDUSTRIES 



The refractive index serves as a preliminary test {cf. p. 109). The 
determination of the Reichert-WoHny value (p. 119) is of importance, 
and should exceed 24 in a "normal" butter. If a lower value be 
obtained, adulteration with other animal fats or vegetable fats may be 
suspected, except in the case of " abnormal " butters. The former are 
introduced into butter mostly in the form of margarine. If the 
margarines contain sesame oil, prescribed by law in some continental 
countries, indications of its presence are obtained by a positive result of 
the Baudouin reaction (p. 129); if this is not the case, the saponification 
value, specific gravity, etc, and other characteristics (see preceding 
Section) must be determined,^ and as margarines contain, as a rule, 
vegetable fats, the phytosteryl acetate test should be applied. 

With the aid of this test the presence of vegetable fats is most 
rapidly ascertained. The detection of small quantities of cocoa-nut 

oil in butter fat is of importance. For this 
purpose E. Polenske's method- is the most 
applicable ; in the absence of better methods, 
this may be regarded as supplementary to the 
ph)'tosteryl acetate test. 

To carr)' out the test, 5 g. of filtered butter 
fat are saponified by heating in a 300 c.c. flask 
over a free flame with 20 g. of gh-cerol and 
2 c.c. of a solution of sodium hydroxide in an 
equal quantity of water (Leffmann and Beam's 
process). The solution is allowed to cool below 
100'', 90 c.c. of water added, and the soap 
brought into solution by warming on a water- 
bath to about 50 . The solution should be 
clear and almost colourless. If a brown solu- 
tion has been obtained, the test must be 
rejected. Then 50 c.c. of dilute sulphuric acid 
(25 c.c. pure concentrated sulphuric acid in 
1000 c.c. water) is added to the hot solution, 
together with some poivdered pumice. The flask is then attached 
immediately to a condenser. The apparatus used must correspond 
precisely in all details with the dimensions given in Fig. 42. The 
heating must be so regulated that 1 10 c.c. distil over in nineteen to 
twenty minutes. The flow of condenser water is regulated so that the 
distillate is collected in the 1 10 c.c. flask at a temperature not exceeding 
20°-23''. As soon as 1 10 c.c. have distilled over, the 1 10 c.c. flask is 
removed and replaced by a measuring cylinder of 20 c.c. capacity. 

^ Cf. Lewkowilsch, Chemical Technology and Analysis of Oils, Fats, and Waxes, vol. ii., p. 667. 
- Arbeiten atis. d, Kaiserl, Gesundheitsamt, 1904, p. 543 ; cf. also R. R. Tallock and R. T. 
Thomson, y. Soc. Chetn. Iiid., 1909, 28, 69. 




Fig. 42. 



BUTTER 157 

The distillate must not be shaken. The flask is immersed almost 
completely in water at 15°; after about five minutes, the neck of the 
flask is gently tapped, so that the drops of oil floating on the surface 
attach themselves to the walls of the flask. After a further lapse of ten 
minutes, the consistency of the insoluble acids is observed, to see whether 
they form a solid or semi-solid mass or oily drops. The contents of 
the flask are then well mixed up, by inverting the closed flask four or 
five times, without, however, shaking it vigorously. Then 100 c.c. are 
filtered off through a filter paper of 8 cm. diameter, and titrated with 
A710 alkali exactly as in the Reichert process (p. 119). In order 
to remove the soluble acid completely, the filter is washed three times 
successively with 1 5 c.c. of water, which have been passed severally 
through the condenser tube, then into the 20 c.c. measuring cylinder, 
and finally into the no c.c. flask. The condenser tube, measuring 
cylinder, and 1 10 c.c. flask are then rinsed out in the same manner 
with three successive washings of 15 c.c. of neutralised 90 per cent, 
alcohol, each washing being allowed to drain off completely before the 
next is brought on to the filter. The alcoholic filtrate is finally titrated 
with N/io alkali. In the following Tableanumber of the values published 
by Polenske for pure butter fats are given, together with the values for 
the same butter fats containing respectively, 10, 15, and 20 per cent, 
of cocoa-nut oil. The expression "new butter value" proposed by 
Polenske has been avoided by the author, as it is better expressed by 
"titration value of the insoluble volatile acids." 

Polenske claimed that with the help of this Table an approximately 
quantitative estimation of the cocoa-nut oil present in an adulterated 
butter could be obtained ; this is based upon the deduction from the 
data in the Table, that the amount of alkali necessary for the neutralisa- 
tion of the insoluble acids is increased by o-i c.c. for each per cent, 
of cocoa-nut oil added. The mode of calculation may be illustrated by 
an example. Suppose a sample of butter fat gave a Reichert-Meissl 
value of 24-5 and required 3-0 c.c. of TV/ 10 alkali for the neutralisation 
of the insoluble volatile fatty acids. The insoluble volatile fatty acids 
were of a liquid consistency. According to the Table a pure butter fat 
of Reichert-Meissl value 24-5 should require only i-6 c.c. of iV/io alkali 
for the neutralisation of the insoluble volatile fatty acids ; hence 
3-0— 1-6 = 1-4 c.c. was necessary for the neutralisation of the insoluble 
volatile acids ; the sample in question must therefore be considered to 
have been adulterated with cocoa-nut oil. As each o-i c.c. of alkali is 
taken to correspond to i per cent, of cocoa-nut oil, the sample is looked 
upon as having been adulterated with 14 per cent, of cocoa-nut oil. 
Examples 15 and 22 of the Table (24-2, 3-0 and 24-8, 3-0) would 
indicate an addition of 10 per cent, of cocoa-nut oil. The sample 
which gave the above figures actually contained lO per cent, of cocoa-nut 



158 



ANALYSIS IN OIL AND FAT INDUSTRIES 



oil. A method based upon the same principle, but differing in the 
practical details, has been described by A. Miintz and H. Coudon,^ 

Table 28. 
Titration Values of Butter Fats. (Polenske.) 



Titration values, i.e., number of c.c. X/10 KOU required for the neutralisation of the :— 




^^ 


09 


^ 


CQ 


j^ 


X 


^ 


93 




X 


S 


~5 




■S5 


•o 


■a s 


2 






'0 




O 




o 




u 




"5 "3 


d 


■5 C3 


e3 


O 03 


o3 


£■ S 


tf 




« > 





« > 


<s 


eS > 


£ 


* > 


S 




0^ 
IT * 


=3 


II 




.2 « 

5~ 


'•3 


il 






cO s 




ea £> 




eS V 




cS » 






oS 




> 


oS 


> 


OS 




oS 


3 

> 




''S 





>J, 


o 


f- 


a> 


" ^ 


a 




© tn 




^ 


•— 1 


C U 




C Im 




No. 


35 


3 

3 


22 


:3 


S 2 


2 


1-2 


3 

3 




3 y 




3 




S'o 




3 U 






l| 


"3 

s 


II 


1 


II 


"3 

03 

a 


II 


"o 

C 








>^ 


t-t 


N.^ 




""^ 






Same butter fat with 


Same butter fat with 


Same butter fat with 




Pure butter fat. 


addition of 10 per cent. 


addition of 15 per cent. 


addition of 20 per cent. 






cocoa-nut oil. 


cocoa-nut oil. 


cocoa-nut oiL 


1 


19-9 


1-35 


18-7 


2-4 


18-1 


2-9 


17-6 


3-3 


2 


21-1 


1-4 


19-7 


2-3 


192 


3-0 


18-5 


3-6 


3 


22-5 


1-5 


21-0 


2-5 


20-4 


2-9 


19-8 


3-5 


4 


23-3 


1-6 


22-0 


2-5 


21-5 


3-1 


21-0 


3-7 


5 


23-4 


1-5 


22-3 


2-4 


21-7 


3-1 


21-2 


3-7 


6 


23-6 


1-7 


22-5 


2-5 


21-9 


3-3 


21-4 


4-0 


7 


21-5 


1-6 


23-3 


2-5 


22-4 


3-1 


21-7 


3-7 


8 


24-7 


1-7 


23-8 


2-9 


22-9 


3-5 


22-1 


3-9 


9 


24-8 


1-7 


23-5 


2-7 


22-7 


3-2 






10 


24-8 


1-6 


23-4 


2-5 


22-8 


3-0 


22-1 


s-'e 


11 


25-0 


1-8 


23-0 


2-7 


23-3 


3-1 


21-8 


3-6 


12 


25-1 


1-6 


23-5 


2-5 


23-1 


3-0 


22-5 


3-8 


13 


25-2 


1-6 


23-4 


2-6 


22-9 


3-0 


22-3 


3-7 


14 


25-3 


1-8 


24-0 


2-9 


23-5 


3-5 


22-6 


41 


15 


25-4 


1-9 


24-2 


3-0 


23-7 


3-6 


22-6 


4-1 


16 


25-6 


1-7 


24-1 


2-7 


23-3 


3-1 


22 "7 


3-7 


17 


25-4 


1-7 


23-8 


2-6 


23-0 


3-1 




... 


18 


26-2 


1-9 


25-0 


31 


24-2 


3-6 


23-6 


4-0 


19 


26-5 


1-9 


25-0 


2-9 


24-1 


3-5 


23-2 


4-1 


20 


26-6 


1-8 


25-4 


2-9 


24-6 


3-3 


23-9 


3-8 


21 


26-7 


2-0 


25-2 


3-2 


24-5 


3-6 


237 


4-2 


22 


26-8 


2-0 


24-8 


3-0 


24-2 


3-4 


23-5 


4-0 


23 


26-9 


2-1 


25-2 


2-9 


24-1 


3-6 


23 2 


4-2 


24 


26-9 


1-9 


24-9 


2-9 


24-0 


3-3 


23-3 


4-0 


25 


27-5 


1-9 


25-7 


2-7 


24-9 


3-3 


24-0 


39 


26 


27-8 


2-2 


26-0 


3-1 


25-0 


3-7 


... 


... 


27 


23-2 


2-3 


26-1 


3-1 


25-1 


3-8 


24-5 


4-4 


28 


28-4 


2-3 


26-5 


3-5 


25-7 


40 


25-1 


4-5 


29 


28-8 


2-2 


26-8 


3-3 


26-0 


3-9 


... 


... 


30 


28-8 


2-5 


27-1 


3-5 


26-3 


4-0 


25-4 


4-7 


31 


29-4 


2-6 


27-6 


3-8 


26-9 


4-2 




... 


32 


29-6 


2-8 


27-5 


3-8 


26-2 


4-2 


25-5 


4-9 


3:5 


29-5 


1 2-5 


27-4 


3-5 


26-6 


4-1 


25-4 


4-7 


34 


30-1 3-0 


27-8 


3-8 


26-9 


4-4 


26-2 


5-0 



It must, however, be clearly pointed out that the titration values 
must not be considered as definite and final indications, as was formerly 

' MoniL Scient., 1904, 18, 530 ; /. Soc. Chem. Ind., 1904, 23, 764 ; cf. Lewkowitsch, Chemical 
Technology, etc., vol. ii.. p. 695. 



BUTTER. MARGARINE. LARD. 159 

supposed ; indeed, as a rule, they do not furnish any more information 
than the Reichert-Meissl value themselves. For the detection of tallow 
and hog's lard in butter fat, with the aid of the "difference number" 
(difference of melting points), cf. Lewkowitsch, Chemical Technology, etc., 
vol. i., p. 324. 

2. Margarine. 

The examination of margarine fat comprises the determination of 
the Reichert-Wollny value, and in those countries in which sesame oil 
must be added, its detection by the Baudouin test. If the quantity of 
milk prescribed by law in this country (10 per cent, of butter fat) has 
not been exceeded in the preparation of the margarine, the Reichert- 
Wollny value must not exceed 4. This is, however, only the case when 
the margarine contains no cocoa-nut oil, but since the latter has come 
into use in the manufacture of margarine Reichert's method must, 
if necessary, be supplemented by Polenske's test. Margarines consisting 
entirely of cocoa-nut oil are readily identified by the Reichert value, 
saponification value, iodine value, and titration value of the insoluble 
volatile acids. 

3. Lard, xA-Rtificial Lard, Lard Substitutes. 

The testing of lard for impurities and the detection of substitutes 
are among the most important problems in the analysis of edible fats. 
The refraction is first observed in a (butyro) refractometer ; the iodine 
value of the fat and that of the liquid acids are also determined. If 
these tests give cause for suspicion, the sample is examined for vegetable 
oils and fats by the phytosteryl acetate test (p. 141). If cocoa-nut oil or 
palm kernel oil is suspected, the Reichert-Meissl (Reichert-Wollny) 
value (p. 119) and the titration value of the insoluble volatile acids 
(Polenske's method, p. 156) are determined. 

The detection of Talloiv or Beef Stearitie is a difficult problem ; for 
information the reader is referred to the monograph on " Lard " in the 
author's Chemical Technologj' and Atialj'sis of Oils, Fats, and Waxes, vol. 
ii., p. 560. 

4. Chocolate Fats, Cocoa-butter Substitutes. 

Under the former of these two terms, the author includes all the 
fats which serve as substitutes for the expensive cocoa-butter in the 
manufacture of cheap chocolates. These are for the most part " cocoa- 
nut oil stearine " and " palm kernel stearine," which are recognised by 
their low iodine values and high saponification values, as also by their 
Reichert-Meissl values. The melting point of these "stearines" is 
frequently raised by the addition of tallow or of oleostearine. The 
determination of the melting point of the fat and the titre test of the 
fatty acids are of importance. 



160 



ANALYSIS IN OIL AND FAT INDUSTRIES 



C.—WOOL OILS. 

These are oils which are used to lubricate the wool fibre previous to 
spinning and weaving. The\' are either pure fatty oils (olive oil, lard 
oil, neat's foot oil) or oleic acid, or mixtures of this acid with unsaponifi- 
able oils (mineral oils, wool-fat hydrocarbons). 

The value of wool oils depends upon the ease with which the\- are 
removed from the fibre by scouring, and further upon their freedom from 
liability to spontaneous combustion. 

The quantitative estimation of the unsaponifiable matter (p. 124) 
furnishes important information. This is insisted upon by Fire Insur- 
ance Companies, as the insurance premium is fixed at a higher rate the 
greater the amount of unsaponifiable matter present. 

The liability to spontaneous combustion is ascertained b)' determin- 
ing the flashing point (cf. the sections on " Mineral Oils," p. 28, and 
" Lubricants," p. yy) ; and, further, in the case of pure oils and pure 

fatty acids, by the behaviour of 
the wool oil to cotton fibre, at a 
somewhat high temperature in 
W. Mackey's "Cloth Oil Tester." 
This apparatus^ (Fig. 43) con- 
sists essentially of a cylindrical 
water-bath, closed by a lid in 
which a thermometer is fixed. 
In the lid are fitted two tubes. 
A and B, through which air is 
circulated in the direction of the 
arrows. The water - bath con- 
tains a wire-gauze cylinder C, 
in which is placed a wad of 
cotton wool impregnated with 
the wool oil under examination. 
To carry out the test, 7 g. of pure cotton wool is weighed out and 
soaked with 14 g. of the wool oil in a flat porcelain dish. This must 
be done carefully so as to distribute the oil uniformly. It is best to 
teaze the cotton wool out and to impregnate it carefully with the 
oil, as the success of the test depends, to a large extent, upon the 
uniform distribution of the oil. The cotton wool containing the oil is 
brought into the cylinder C, the thermometer being held firmly so that 
the cotton wool is packed round the mercury bulb. The water in the 
steam jacket is heated until it boils vigorously, the C)-linder introduced 
into the bath, the cover brought down over the thermometer and held 
in place by the clamp D. After about an hour, during which time the 

1 Made by Messrs Reynolds & Branson, Leeds. 




Fi.i. 4S. 



LINSEED OIL 



161 



water is kept boiling vigorously, the temperature is observed. Moisture 
must be rigorously excluded. 

If, after an hour, the thermometer shows a temperature exceeding 
ioo°, the oil is considered as liable to spontaneous combustion. In the 
case of very dangerous oils the temperature rises to 200° within forty- 
five minutes. If the temperature rises above 150° it is advisable to 
remove the thermometer, as the oiled cotton wool easily becomes ignited. 

This method gives only comparative values ; hence the details must 
be precisely observed. Before proceeding with the experiment, it is 
advisable to test olive oil and pure cotton-seed oil as examples, 
representing a safe and a dangerous oil respectively. 

Z*.— LITHOGRAPHIC VARNISHES— POLYMERISED 

LINSEED OILS. 

Lithographic varnishes are obtained by heating drying oils — chiefly 
linseed oil — to high temperatures in absence of air. The more strongly 
the oil is heated the more energetic is the resulting polymerisation. 
The determination of the iodine value does not furnish sufficient data 
for the valuation of such oils. According to the author,^ the determina- 
tion of the yield of insoluble bromides (p. 138) gives reliable results. 
Thus, whilst raw linseed oil yields up to 42 per cent, of insoluble (hexa) 
bromides, the yield in the case of highly polymerised oils falls to zero. 

The data given in the following Table will serve as a guide in the 
interpretation of the values found. 

Table 29. 

Values of Polymerised Linseed Oils — Lithograph Varnishes. 

(Lewkowitsch.) 







OJ 








CO 










>, 






b 
§ 


> 




m 

1 








"3 


a5 
3 


03 


-.J 

a 



-a 




■4^ 

ClC 

m 


'3 



> 



"as 


^1 

a 

w 


Oxidised fat 


§1 
rv e8 





> 

'0 


> 


3;a 

"3 '3 
> a 

a 




3 










Pur 




Per 


Per 


Per 








Per 










cent. 




cent. 


cent. 


cent. 








cent. 


Raw linseed oil 


0-9308 


... 


186-4 


24-17 


... 


... 














Linseed oil heated 


























to 310° 


0-9354 


... 


176-3 


8-44 


















Thin varnish I. 


0-9676 


189-5 


107-7 


0-17 


94-75 


4-17 


1-76 


9-71 


6-09 


6-5 


114-74 


39-31 


n. . 


0-9691 


193-0 


125-3 


2-0 


94-8 


0-34 


0-13 












Medium varnish I. . 


0-9693 


194-4 


121-9 


0-95 


93-8 


1-48 


0-57 












II . 


0-9703 


190-5 


126-5 


0-0 




1-53 


1-8 












Thick oil I. 


9720 


190-0 


109-4 


0-24 


94-68 


6-36 


1-45 


9-17 


5-12 


1-65 


13-53 


32-31 


„ IF. . . 


0-9747 


193-7 


118-5 


0-0 


95-6 


0-36 


0-25 












Burnt varnish . 


0-9912 


178-6 


102-69 


0-0 


93-53 


9-12 


1-14 




... 




... 


... 



Analyst^ 1904, 29, 2. 



Ill 



162 ANALYSIS IN OIL AND FaT INDUSTRIES 



£.— "BOILED" LINSEED OIL, LINSEED OIL VARNISH, 

VARNISH OILS. 

The term " boiled " oil originates from the times when the now 
almost obsolete process of heating the oil over free fire to 2io°-26o^, 
with the addition of suitable metallic salts or metallic oxides (siccatives, 
driers) was practised. Now " boiled " oil is prepared by heating linseed 
oil by steam to 150°, at the same time mixing the oil intimately with 
added siccatives by vigorous stirring. According to the nature and 
quantity of the siccative and the duration of the heating, the resulting 
product is a "pale boiled oil" or "double boiled oil." ^ 

Linseed oil is practically the only drying vegetable oil which serves 
for the technical preparation of good boiled oil. 

The examination of the raw materials comprises the testing of: — 

1. The Linseed Oil. 

2. The Siccatives. 

I. Linseed Oil. 

The specific gravity should not be below 0-930. The iodine value 
should be as high as possible, but at least 170, and the higher the 
better. The oil must be free from adulterants such as marine animal 
oils (bromide test), rosin oils, mineral oils, and rosin acids (colophony). 

For the valuation of a linseed oil which has been found to be free 
from impurities, the time it requires to dry is of importance. In 
addition to the determination of the time required to dry to an elastic 
skin, the valuation of a linseed oil for varnish manufacture often 
includes the determination of the quantity of oxygen which it absorbs. 
Livache's method and the glass plate method (p. 127) may indeed be 
used for quantitative measurements, but, except in special cases, these 
give but little information. It is of far greater importance to ascertain 
the time of drying and the consistency of the elastic skin. This is 
done by the method generally used in practice. Much experience is, 
however, required in order to judge an oil by the drying test. In 
examining an oil it is therefore advisable to make comparative tests 
with a boiled oil known to be pure and of good drying quality, on glass 
plates covered with a thin la\'er of the oil (spread with the aid of a 
spatula, not with a brush). A good linseed oil should dry in less than 
three days ; after this time it should not be sticky to the touch and 
should give a coherent, elastic skin. (Oils containing considerable 
(juantities of unsaponifiable matter or foreign oils are recognised as 
adulterated by this test alone, as the presence of the impurities prevents 
the formation of a good elastic skin.) 

' For the theory of the process of "boiling" and further details, and the preparation of 
varnishes at ordinary temperatures, cf. Lewkowitsch. Chemical Technology of Oils, etc., vol iii., 

r- 138. 



LINSEED OIL 163 

An important test for judging the suitability of a linseed oil for 
boiled oil (and especially for varnishes), consists in heating the oil in a 
test tube until it begins to boil. Good oil remains clear (it generally 
becomes somewhat paler after heating) ; if a mucilaginous mass 
(" spawn," " break ") separates out, the oil must be rejected as unsuit- 
able. In the case of oils of inferior quality the "spawn" extends 
through the whole mass of the oil like frog spawn. Such oils are 
useless for the manufacture of boiled oil and varnish in this condition. 
Freshly expressed ("green") linseed oil froths on heating, whereas old 
" tanked " oils, from which water and mucilage have settled out, do not 
froth. As the latter are most suitable for the above-named purposes, 
the preference of the manufacturers for "tanked" oil is readily under- 
stood. The mucilaginous mass consists, as G. Thompson ^ has shown, to 
the extent of one-half of phosphates (and sulphates) of calcium and 
magnesium, which on settling out carry down with them organic 
impurities. 

2. SlCCATIVES.2 

In the older processes for the manufacture of varnishes the only 
drying agents used were Oxides of lead and manganese, such as massicot, 
red lead, and pyrolusite. The salts of zinc, copper, and iron do not 
possess the property of imparting the desired effect to the oil. More 
recently, manganese acetate, oxalate, and borate have also come into 
use. As colophony absorbs oxygen from the air, the metallic salts of 
rosin acids, lead rosinate, manganese rosinate, and calcium rosinate are 
also employed as siccatives. The metallic salts of the rosin acids are 
prepared either by precipitating solutions of their sodium salts with 
metallic salts {e.g. sodium rosinate and manganese sulphate), or by 
melting together a metallic oxide with colophony. Hence, a distinction 
is made in commerce between " precipitated " siccatives and " molten " 
siccatives. By melting or precipitating colophony with a mixture of 
manganese and lead salts, " molten " or " precipitated " as the case may 
be, manganese-lead siccatives are obtained. A simple method of 
distinguishing between "molten" and "precipitated" siccatives is to 
determine the proportion of water. Only the " precipitated " siccatives 
contain a considerable quantity of water (up to 6 per cent). The 
degree of fineness is also of importance. The further valuation of these 
siccatives is carried out by the ordinary methods of mineral analysis. 

A further development in the industry of driers is the use of metallic 
salts of the fatty acids of linseed oil. These salts are prepared either 
by precipitating soap solutions (obtained by the saponification of 
linseed oil with caustic soda) with metallic salts, or by melting together 

1 y. Soc. Chem. Ind., 1903, 22, 1 005. 

'■^ C/. Weger, Z. angew. Chem., 1896, 9, 531 ; 1897, 10, 401, 542, 560 ; y. Soc. Chem. hid., 
1896, 15, 728 ; 1898, 17, 360. 



164 ANALYSIS I\ OH. AND FAT INDUSTRIES 

the fattv acids and metallic oxides. In this manner " precipitated " and 
" molten " manganese and lead linoleates are obtained. The salts 
derived from linseed oil fatty acids and colophony are soluble in 
turpentine, ether, chloroform, and in linseed oil ; hence they are termed 
"soluble siccatives." Solutions of such siccatives in linseed oil or 
turpentine, or in mixtures of these, are met with in commerce under 
fancy names, such as " liquid driers," " terebene," etc. 

The valuation of the Soluble Siccatives cannot be based upon the 
content of metal, as found by direct ignition and weighing the ash, 
since suspended metallic oxides, which are not chemically combined to 
fatty acids or rosin acids, are not only useless, but actually detrimental 
to the manufacture, as they render the finished product turbid. As a 
preliminary test, the drier is treated with organic solvents, A good 
drier should dissolve completely in ether, or in the case of lead rosinate, in 
chloroform and in turpentine. (Turpentine also dissolves lead rosinate 
on warming, but the dissolved siccative separates out again on cooling.) 

In the analysis of a Soluble Drier, the organic component is first 
burnt off in a porcelain crucible, and the lead, manganese, etc., deter- 
mined in the ash. The weight of the ash alone does not always give 
reliable results, as the " molten " siccatives often contain sand, etc. 
Besides lead and manganese, calcium should also be determined in the 
ash. (Calcium rosinate is admissible as a component of driers.) A fresh 
portion of the sample is then extracted with ether, chloroform, or 
turpentine, the solution filtered, the solvent evaporated off, and the 
residue incinerated. In the ash the lead or manganese (or both) are" 
determined quantitatively ; the difference between the lead and 
manganese found, and the proportion of these metals in the original 
determination corresponds to the weight of lead and manganese present 
as insoluble excess. The result may be checked by the determination 
of the dissolved metal in an aliquot part of the solution. In case of a 
rosinate, the dissolved lead must be determined by difference, as it is 
stated that chloroform can be removed completely from the rosinate 
only at a red heat, at which temperature part of the lead chloride 
volatilises. 

The determination and examination of the fatty and rosin acids {cf. 
p. 195) is of less importance; it can, however, be carried out by decom- 
posing the ethereal solution with a mineral acid. It must, however, be 
emphasised that the chemical examination does not furnish sufficient 
information as to the "drying" properties of the siccative. The colour 
of the boiled oil to be prepared, its drying properties and other 
conditions, are the determining factors in the choice and quantity of a 
drier. 

The chemical examination of the finished boiled oil comprises the 
detection of adulterants such as marine animal oils, vegetable oils other 



LINSEED OIL 



165 



than linseed oil, mineral oils, rosin oils, and colophony. Oils which 
have been prepared with liquid siccatives may contain small quantities 
of turpentine as a legitimate ingredient. The so-called "patent 
varnishes " are mostly adulterated oils. 

Boiled Linseed Oil is distinguished from raw linseed oil by its 
higher specific gravity — above 0-94— also by the presence of a drier ; 
hence on incinerating the oil a residue remains. Boiled oil is frequently 
mixed with raw linseed oil, as boiled oil when used alone sometimes 
gives a " hard " surface which readily cracks ; hence a method for the 
detection of raw linseed oil in the boiled oil is only of some importance 
in those countries in which linseed oil and boiled oil pay different 
Customs duties. 

The best method for the detection and approximate estimation of 
raw linseed oil in boiled oil which has been manufactured at hio-h 
temperatures is the bromide test ^ (p. 13S). A number of data in 
regard to linseed oils are given in the following Table : — 

Table 30. 
Values for Linseed Oils. (Lewkowitsch.) 







Sp. gr 


Iodine 


Insoluble bromides 






value 


from the glycerides 










Per cent. 


Linseed 


oil (raw) 


0-9308 


186-4 


24-17 




(light boiled) . 


0-9429 


171-0 


20-97 




(double boiled . 


0-9449 


169-96 


13-03 




(ozonised) 


0-9310 


180-1 


36-26 to 36-34 




M • • 


0-9388 


171-2 


25-73 




» 


0-9483 


169-7 


30-19 



The quantity of oxidised acids (p. 139) in boiled oils should not 
exceed a iew per cent. 

It should be noted that in consequence of the presence of metals in 
boiled oils, the iodine value found is too high, unless the metal be 
previously removed by treatment with mineral acids. The magnitude 
of the error which may result from this cause is shown by the following 
data : — 



Varnish oil from 


Original boiled oil. 


After separating 
the metal. 


Linseed oil . . ' 


173-3 
177-2 


169-7 
171-1 



The valuation of a boiled oil which has been found free from 

^ Lewkowitsch, Analyst^ 1904) 29, 2. 



16G ANALYSIS IN OIL AND FAT INDUSTRIES 

adulterants must be based on practical tests, the oil being spread out 
in a thin layer on glass plates and exposed to the air as described on 
p. 127. The boiled oil is taken either in its original state, or mixed 
with pigments, such as are used for paints. A weighed or measured 
quantity of the boiled oil is very intimately mixed with a weighed 
quantity of pigment on a glass plate, the mixture spread out in a thin 
la\'er, and exposed to the air, side by side with a paint prepared in 
precisely the same way with a boiled oil of good quality. Practical 
experience is, however, indispensable to arrive at a correct opinion. 

Boiled linseed oil is used extensively for the preparation of paints 
and varnishes. 

/^.—LINSEED OIL PAINTS AND VARNISHES. 

Linseed Oil Paints. — No great difficulties are involved in the 
testing of linseed oil paints. The paint is shaken with ether, a mineral 
acid added to decompose the metal soap and to bring it into solution, 
in case it be soluble in acids, and the ethereal solution separated from 
the aqueous solution and from any insoluble residue. After evaporat- 
ing off the ether the residual oil maybe further tested. The mineral 
substances are examined by the usual methods of mineral analysis. 
The oil content, as a rule, amounts to 8-10 per cent, in the case of 
white lead, and to 30-40 per cent, in the case of black paints ; other 
pigments require intermediate amounts. 

Varnishes consist of a mixture of boiled oil, with various gum resins . 
and oil of turpentine.' 

The preparation of these products is guarded as a valuable trade 
secret. The "art" of the manufacturer lies in the choice of suitable 
gum resins, and in the treatment of these previous to their introduction 
into the boiled oil. Most gum resins must be heated beforehand to over 
2,00^. This causes them to melt and to undergo a partial decomposition, 
certain oily products distilling over; the loss of weight caused by this 
treatment is from 5 to 25 percent. In the manufacture the melted gum 
resins are dissolved whilst hot in a drying oil or a boiled oil ; in 
the former case the oil is " boiled " after the addition of a suitable drier. 
The product thus obtained is termed " varnish oil." The varnish oil is 
allowed to stand, so that "foots" may separate out, or it is filtered 
through a filter press. Finally, the commercial enamel varnish is 
prepared by diluting the "varnish oil " with turpentine. 

The most suitable oil, and in fact the only oil which is used for the 
manufacture of the best varnishes, is linseed oil. A large number 
of patents has been taken out for the manufacture of linseed oil 

^ Lacquers are simple solutions of gum resins in alcohol, turpeniine, fusel oil, etc., the 
examination of which lies outside the scope of ih'S section. 



LINSEED OIL PAINTS AND VARNISHES 167 

substitutes, the linseed oil being replaced by tung oil, or by a mixture of 
linseed and tung oils. In most of the products thus prepared which 
have come under the author's notice, the expensive gum resins had been 
replaced by colophony. 

The oil of turpentine is also frequently replaced by cheaper hydro- 
carbons, especially by petroleum hydrocarbons of the same boiling point. 

A complete chemical examination of varnish oils is in our present 
state of knowledge a very difficult problem. Whilst the fatty oil used 
and the volatile solvent can be more or less easily identified, it is in 
some cases absolutely impossible to identify the gum resins by chemical 
means alone, and an extended practical experience is necessary 
to interpret the results furnished by the chemical tests 

In the chemical examination of a varnish the volatile solvent is first 
isolated by distilling lOO g. of the varnish in steam until no more 
volatile oil passes over. The examination of the volatile oil is 
comparatively simple; the specific gravity, boiling point, and iodine 
value of the sample yield the requisite data. The iodine values 
of genuine American turpentine from the live tree lie between 370 and 
400. Oil from the dead w^ood, such as " Kienol," has a lower iodine 
value.^ 

The residue remaining in the flask is freed from water and the 
quantity of fatty oil is estimated approximately by determining the 
quantity of glycerol obtained after saponification. The separation of 
the gum resins from the boiled oil cannot always be satisfactorily 
effected. The usual characteristics of the gum resins do not always 
yield sufficient information, as their composition is completely altered 
on heating to 300^ The values given in the following Table ^ may 
furnish useful information. 

The examination of the ash shows what metal or metals were 
present in the siccative. Considerable quantities of lime in the ash 
indicate the presence of calcium rosinate, which is frequently added in 
much too large proportion in order to impart a fictitious hardness and 
lustre to the dried varnish. 

The chemical examination must be supplemented by "practical" 
tests. The practical examination of the fatty oil as to its usefulness 
and drying properties is carried out in a similar manner to that 
described above under boiled oil. The influence of atmospheric 
conditions (moisture, light, etc.) can only be determined by practical 
tests either of the varnish alone, or in admixture with pigments. 

Enamels.' — This is the technical term for mixtures of varnish with 
pigments such as zinc oxide, lead oxide, iron oxide, etc. Their chemical 

^ Cf. Lewkowitsch, Chemical Technology, etc., vol. iii., p. I2i. 

^ Cf. Lewkowitsch, Analyst, 1901, 26, 37. 

* Not to be confused with the enamels of the ceramic industry. 



168 



ANALYSIS IN OIL AND I AT INDUSTRIES 



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OXIDISED OILS 169 

examination consists in a combination of the methods given for linseed 
oil paints and varnishes. 

6^.— OXIDISED OILS. 

Under this term the author includes all those oils which have 
taken up oxygen on exposure to the air, or have been oxidised 
artifically by heating (" blowing ") in a current of air or oxygen. 

It is convenient to subdivide the oxidised oils into two groups. 

I. Oxidised Oils, obtained from Semi-drying Vegetable 
Oils, Marine Animal Oils, and Liquid Waxes. 

These oils (commercially known as " blown oils," " thickened oils," 
"soluble castor oil") are obtained by treating vegetable semi-drying 
oils, marine animal oils, or liquid waxes, with a current of air at 
a somewhat high tem.perature whereby the density and viscosity of the 
oils are increased. They thus approximate in their properties to castor 
oil, but differ from the latter by being miscible with mineral oils — hence 
their designation as "soluble castor oil." They further differ from 
castor oil in their insolubility in alcohol. The most striking chemical 
change which accompanies the "blowing" is that a considerable 
quantity of soluble fatty acids and of oxidised fatty acids are formed. 
For this reason these oils have high saponification values and somewhat 
high Reichert-Meissl values. Their acetyl values are also high.^ 

The blown oils are used com.mercially as lubricants, for the most 
part in admixture with mineral oils, fatty oils, and rosin oils. 

2. Oxidised Oils obtained from Drying Oils. 

When drying vegetable oils are exposed to the air or to a current of 
air or oxygen at somewhat high temperatures, the production of the 
oxidised acids proceeds much more rapidly than is the case with semi- 
drying oils. Extended use is made of this property in the employment 
of paints and varnishes, the vegetable oil — especially linseed oil — drying 
finally to a solid mass which forms a continuous skin on the surface 
of the object with which the paint or varnish is coated. 

The chemical change which occurs when a vegetable oil dries to a 
solid elastic skin has been only incompletely investigated. The process 
seems to be the same whether raw linseed oil absorbs oxygen from the 
air, or whether the drying is accelerated by conversion of the oil into a 
" boiled " oil, or finally, whether the raw linseed oil is treated with 
a current of oxygen at higher temperatures after the addition of driers. 

It is probable that in the first stage the linolenic acids of the linseed 

^ Detailed Tables, showing the characteristics of "blown" oils, are given in Lewkowitsch's 
Chemical Technology^ etc., vol. iii., pp. 132 et seg. 



170 ANALYSIS IN OIL AND FAT INULSTHIES 

oil are attacked ; the iodine values decrease and the amount of oxidised 
fatt)' acids increases. When the oxidation of the linseed oil is carried 
further, i.e. until the linseed oil has taken up the maximum quantity of 
oxygen, a gelatinous solid mass is obtained, which is known as " solid 
linseed oil," or "oxidised linseed oil" ("linoxyn ").^ 

Solid linseed oil is used very extensively for the manufacture 
of Lino/eimi, the solid oil being mixed with various gum resins, 
powdered cork, and materials added to increase the weight. The mass 
thus obtained is called Liuoleiun Cement. It is pressed on a jute cloth 
by means of rollers, and finally allowed to "ripen" at a temperature of 
about 20 . The valuation of linoleum depends almost entirely upon 
practical tests. The chemical examination consists in the determination 
of the ash and the treatment of the powdered mass with ether. Any 
considerable quantity of linseed oil in the extract in addition to gum 
resins would indicate that the oil has not been treated sufificientl}' long 
with oxygen. The methods of testing used by the Techuische 
Versuchs-Anstalten in Germany- have been adversely criticised by H. 
Ingle,-'' who has proposed alternative methods. 

//.—VULCANISED OILS, INDIARUBBER SUBSTITUTES. 

See the section on " Indiarubber and Rubber Goods," this Vol., 
pp. 398 et seq. 

/.— SULPHONATED OILS, TURKEY RED OILS. 

Turkey red oils are thick, oily, dark yellow liquids, which are used 
in printing and dyeing cotton. The part which they play in fixing the 
dye is not yet fully elucidated. Genuine Turkey red oil is prepared by 
the action of concentrated sulphuric acid on castor oil. The resulting 
oil is isolated by drawing off the acid layer, washing with sodium 
sulphate solution, and partially neutralising the acid with caustic soda 
solution or ammonia until the product gives a perfectly clear solution 
with a little water. 

The portion of the product of the action of sulphuric acid on castor 
oil which is soluble in water contains for the most part ricinoleo- 
sulphuric acid, which is partially hydrolysed by boiling with dilute 
acids into sulphuric acid and ricinoleic acid (a further portion is 
converted to inner anhydrides of ricinoleic acid). The portion insoluble 

' For recent views as to the process of drying, cf. Lewkowitsch, Chemical Technology, etc., 
vol. iii., p. 139. 

"^ H. Bjrchartz, Mitt, kdnigl. tech. Versuchsarist., 1899, 17, 285 ; /. Soc. Chetn. hid., 1900, 

19. 255- 

•' y. Soc. Chem. Ind., 1904, 23, 1197; cf. Lewkowitsch, Chemical Technology, etc., vol. ii., 
p. 146. 



SULPHONATED OILS. TURKEY RED OILS 171 

in water contains ricinoleic acid and anhydrides of this acid, together 
with unchanged oil (neutral fat). The testing of Turkey red oil consists 
of preliminary tests (chiefly a dyeing test) and the determination of the 
chemical characteristics. 

Prelii/iifiary Tests. — Turkey red oil should give a perfect emulsion 
with lo vols, of water; no drops of oil should separate until the 
emulsion has stood for a long time. The emulsion is compared with 
an emulsion prepared in exactly the same way from an oil known to 
be of good quality. If an excess of alkali is present it must be reduced 
to a minimum by the addition, drop by drop, of dilute acetic acid. 
The emulsion should react faintly acid towards litmus. A good oil 
should dissolve to a fairly clear solution in all proportions of ammonia, 
and on diluting considerably only a slight turbidity should result. 

For the dyeing test the oil under examination is diluted (together 
with a check sample) in 15-20 parts of water, and pieces of cotton cloth 
of equal size are soaked in exactly the same manner with the two 
diluted Turkey red oils. The cloths are then dried, mordanted with 
alumina, and dyed with alizarin. Recently paranitraniline red has been 
preferred by practical dyers. It is difficult for anyone who has not had 
practical experience to judge a Turkey red oil correctly on the strength 
of the dyeing test alone. 

Determination of the Characteristics. — The value of a Turkey red oil 
is primarily dependent upon the proportion of total fat contained, that 
is, upon the sum of the insoluble fatty acids and the neutral fat which 
separate out when the oil is decomposed by boiling with dilute acids. 

The total fat is determined as follows : — A small deep porcelain 
dish of 100-150 c.c. capacity is tared together with a glass rod; then 
3-4 g. of Turkey red oil are weighed into it and stirred with 20 c.c. of 
water, which is gradually added. If the liquid becomes turbid, a drop 
of phenolphthalein solution is added and ammonia run in carefully until 
the red colour persists ; this produces a clear solution. Then 30 c.c. of 
dilute sulphuric acid (1:4) and 5-8 g. of beeswax are added, and the 
whole heated to gentle boiling until the oil layer has separated out 
completely. The solution is allowed to cool, the solidified cake of fat 
is lifted out with the aid of the glass rod, treated as described under the 
analysis of "Soap" (p. 191), and weighed. The weight of the beeswax 
is, of course, deducted from the total weight. 

The following shortened method, described by Finsler, and recom- 
mended by F. Breindl,^ is often used in works : — 30 g. of the sample 
are accurately weighed out and rinsed into a flask of about 200 c.c. 
capacity with about 70 c.c. of hot water. The neck of the flask is 
divided in \ or ^^ c.c. To the contents of the flask 25 c.c. of sulphuric 
acid of sp. gr. 1-563 are added and the mixture is heated, with frequent 

1 Miiteil. d. k. L Tech. gew. Museums, 1888, p. 81 ; /. Soc, Chem, Ind., 1889, 8, 573. 



172 ANALYSIS IN OIL AND FAT INDUSTRIES 

shaking, to boiling until the fatty matter forms a clear, transparent 
layer. A hot saturated solution of common salt or sodium sulphate is 
then carefully added to raise the layer of fatty matter completely into 
the neck of the flask. After standing for about half an hour the volume 
of the fat is read off. The number of cubic centimetres found multiplied 
by 3-33 corresponds to the percentage of the total fat. As, however, the 
specific gravity of the fatty matter is, as a rule, 0-945, ^ corresponding 
correction must be applied. 

The total amount of fatty matter thus found is less than the actual 
sulphonated oil dissolved in the water by the amount of sulphuric acid 
split off on boiling with hydrochloric acid. 

In addition to the total fatty matter the examination also comprises 
the determination of (<^) Neutral Fat, (/') Sulphonated Fatty Acids, 
(c) Alkalis (Ammonia and Soda), (d) Sulphuric Acid. 

(a) Neutral Fat. — 30 g. of the sample are dissolved in 50 c.c. of 
water, treated with 20 c.c. of ammonia and 30 c.c. of glycerol, and 
extracted two or three times successively with 100 c.c. of ether. The 
combined ethereal extracts are washed with water, the ether distilled 
off from a small weighed flask, and the residue dried in the flask at 100° 
and weighed. 

(b) Sulphonated Fatty Acids. — For their estimation 4 g. of the 
sample are boiled in an Erlenmeyer flask with 30 c.c. of dilute sulphuric 
acid (i : 5) for forty minutes, with frequent shaking. After cooling, the 
liquid is transferred to a separating funnel and extracted with ether. 
The aqueous layer is drawn off and the ethereal layer washed with 
water. The washings are added to the main portion of the aqueous 
solution, and the sulphuric acid is estimated by precipitation with 
barium chloride. A deduction must be made from the amount of 
sulphuric acid found, to allow for any sodium or ammonium sulphate 
present as estimated under {d). The difference is calculated to 
recinoleic acid. 80 parts SO3 correspond to 378 parts of recinoleo- 
sulphuric acid, Cj3H3.jO.vO.SO3H. 

(c) Amvio7iiiiin or Sodium Hydroxide. — From 7-10 g. of the sample 
are dissolved in ether and shaken out with four successive amounts of 
5 c.c. of dilute sulphuric acid. 

For the determination of the ammonia the acid liquid is distilled 
with potassium hydroxide solution in the usual way and the evolved 
ammonia absorbed in a known volume of standard acid. 

For the determination of sodium hydroxide the acid liquid is 
evaporated in a platinum dish on a water-bath, the excess of sulphuric 
acid driven off by heating on a sand-bath, the residue mixed with 
ammonium sulphate, ignited, and the remaining sodium sulphate 
weighed. 

(d) Sulphuric Acid. — The sulphuric acid which is present as 



STEARINE CANDLES 173 

ammonium or sodium sulphate is determined by dissolving a weighed 
quantity of the sample in ether, and shaking out several times with a 
few cubic centimetres of concentrated salt solution which is free from 
sulphate. The total washings are diluted, filtered, and the filtrate 
precipitated with barium chloride. 

If it be required to determine the nature of the oils used in the 
preparation of the Turkey red oil, the acetyl value of the total quantity 
of fat must be determined. 

If the acetyl value is 125 or more, the oil is derived from pure 
castor oil; if other material has been used, the acetyl value is 
lower. 

AT.— THE CANDLE INDUSTRY. 

The tallow candle industry is now practically extinct. At present 
the candles met with in commerce are — i, Stearine Candles, generally 
containing considerable amounts of paraffin wax ; 2. Paraffin Candles, 
always containing small additions of stearine ; 3. Spermaceti Candles ; 
4. Wax Candles (beeswax candles). Ceresin is not used solely as 
a material for candles^ but it is employed extensively in the 
manufacture of night-lights. 

I. Stearine Candles. 

The materials used in the manufacture of "stearine" ("stearic 
acid ") for candles are primarily beef and mutton tallow, bone fat, and 
palm oil. Less important raw materials are some solid vegetable fats, 
such as Chinese tallow, Malabar tallow, shea-butter, etc. In the candle 
industry three main products are obtained, i. A mixture of solid fatty 
acids known as " stearine," the actual candle material; 2. " Oleine " or 
technical oleic acid, which is used in the manufacture of soaps or as 
wool oil ; and 3. Glycerin. The resolution of the fats into free fatty 
acids and glycerol is efifected by one of the following processes : — • 
(i) Treatment with water under high pressure; (2) Hydrolysis with 
lime or magnesia or zinc dust ; (3) Hydrolysis by means of concentrated 
sulphuric acid ; (4) The combination of methods 2 and 3 ; (5) Hydro- 
lysis by means of Twitchell's reagent (prepared by allowing an excess 
of sulphuric acid to act on a solution of oleic acid in aromatic hydro- 
carbons). The solid fatty acids obtained by these processes and 
separated by pressing the liquid fatty acids differ considerably in 
value, for whereas those prepared by methods i, 2, and 5 consist 
essentially of the solid acids originally present in the fats (chiefly 
palmitic and stearic acids), concentrated sulphuric acid converts oleic 
acid partially into " iso-oleic " acid, a solid mixture of several isomeric 
oleic acids, capable of being used as a candle material, and solid 
stearolactone. 



]7t ANALYSIS IN OIL AND FAT INDUSTRIES 

(a) Testing of the Raw Material. 

The proportion of water and the quantity of non-fatty substance 
are of importance. These are first determined. The solidifying point 
of the fatty acids and the colour of the fat are also of great importance. 
It is frequently required to determine the unsaponifiable matter, the 
free acids, the oleic acid, and the yield of glycerol. A description of 
these determinations has been given in the main in the preceding 
Section, to which the following details are a necessary supplement. 

1. Fats Zi'hich contain targe quantities of Unsaponifiable Matter — e.g. 
certain kinds of shea-butter, containing 15 per cent, of unsaponifiable 
matter — are unsuitable for the manufacture of candles. A small quantity 
of unsaponifiable matter such as is found in bone fats is not detrimental. 

2. The Solidifying point of the Fatty Acids, termed in commerce the 
"Titre" ("tallow titre "), is the most important criterion for the valua- 
tion of the raw materials for use in the manufacture of candles. The 
higher the titre the more valuable is the material. As it is necessary 
in determining the titre, by which tallows are mostly sold, to adhere 
precisely to a standard method of working in order to avoid differences 
of even tenths of a degree, it is necessary to give a detailed description 
of the method of determining the titre as adopted by the International 
Congress of Applied Chemistry in London in 1909.^ 

The method proposed originally by Dalican has been adopted in 
England, France, and the United States for the testing and valuation 
of commercial fats. It gives reliable results and constant figures in 
duplicate examinations, as the author can confirm from his own ' 
experience, so long as care is taken to perform the test under precisely 
the same conditions. 

For the determination, 50 g. of the sample are saponified by heating 
with 40 c.c. of aqueous potassium hydroxide solution ofsp.gr. 1-4 and 
40 c.c. of strong alcohol in a flask under a reflux condenser, or in a 
porcelain dish on the water-bath. A flask is preferable for hard fats, 
to ensure complete saponification. The soap solution is freed from 
alcohol, dissolved in 1000 c.c. of water, and the fatty acids liberated with 
sulphuric acid, separated from the water, and finally filtered through 
a dry pleated filter into a porcelain dish. The fatty acids are then 
allowed to solidify in a desiccator and left to stand over night. (Accord- 
ing to the resolutions of the Congress it is permissible to determine the 
titre after a few hours' standin;^ in cases of exceptional urgency.) On 
the following day the fatty substance is carefully melted in an air-bath 
or over a free flame, and enough is poured into a test tube 16 cm. long 
and 3-5 cm. broad to fill the tube more than half full. The tube is then 
fitted by means of a cork into a wide-mouthed bottle, 10 cm. wide and 

^ Comptes rendus de la Commission inlernationaU d' Analyses au I7//"'< Congres Inttrnalional 
de la Chimie applttjucr, par L. I indet, Paris, 1909 p. 181. 



STEARINE CANDLES 



175 



13 cm. high, and an accurate thermometer divided in yV degrees is 
immersed in the fatty acids, so that the bulb is in the middle of the mass. 
The tube is then allowed to cool slowly. As soon as crystals are seen 
at the bottom of the test tube the mass is stirred by means of the 
thermometer, first three times from right to left, and then three times 
from left to right. The stirring is continued rapidly with the thermo- 
meter, care being taken that it does not touch the sides of the tube, so 
that all solidified particles are well stirred into the mass as soon as they 
appear ; the fatty acids then become turbid throughout the whole mass. 
The temperature is now carefully watched. It first falls, and then 
suddenly rises a few tenths of a degree, reaching a maximum and 
remaining at this point for a short time before it falls again. The 
maximum temperature observed is called the " Titre " or solidifying 
point. 

R. Finkener ^ uses large quantities of fatty acids in a small pear- 
shaped flask of about 50 mm. diameter. To avoid rapid cooling, he 
places the vessel containing the molten 
fatty acids in a wooden box (Fig. 44). 
This apparatus has been adopted as the 
official apparatus in the German Custom 
offices. In Austria the process proposed 
by F. Wolfbauer- is used in technical 
work. In this method the fatty acids 
(from 120 g. of the sample) are dried 
for two hours at lOO"' ; the rest of the 
determination is carried out exactly as 
described above. 

A. Shukoff-^ has constructed an ap- 
paratus by means of which it is possible 
to avoid small personal errors, which consists of a vessel surrounded by 
a Dewar vacuum jacket ; this prevents too rapid cooling of the fatty 
acids on the walls of the vessel. The dimensions of the apparatus are 
given in Fig. 45. 

For the determination, 30-40 g. of the melted fatty acids are poured 
into the inner vessel, which is then closed by a cork, through which 
passes a thermometer divided into i degrees. When the temperature 
has fallen to about 5° above the presumable solidifying point, the vessel 
is vigorously and regularly shaken up and down, until the contents are 
distinctly turbid and opaque. The thermometer is then closely watched 
to observe the maximum temperature of solidification. 





Fio. 41. 



Fig 45. 



1 Mitt. K. techn. Versuchanst, 1889, p. 27 ; 1890, p. 153 ; /. Soc. Chem, hid., 1889, 8, 423 ; 
1890, 9, 1671. C/. also Lewkowitsch, Chemical Technology^ etc., vol. i., p. 501. 

- Milt. tech?!. Gew. Museums, 1891, p. 57 \ J. S'o:. Chem. hid., 1894, 13, 181, 908. 
3 Chem. Rev. Fett-fnd., 1899, 6, li. 



176 ANALYSIS IN OIL AND FAT INDUSTRIES 

Shukoft" showed subsequently^ that the vacuum jacket is not 
absolutely necessary, and that equally good results are obtained when a 
test tube 2^-3 cm. wide, fitted with a thermometer, is fixed by means 
of a cork into the neck of a wide-mouthed bottle. 

Titre tests of the fatty acids are given in Table 26, pp. 150 et seq. 
of the previous Section. 

3. TJic Colour is an important criterion in the valuation of tallow. 
Imported tallows, which are chiefly dealt with on the English market, 
are therefore sold under such names as " good colour," " off colour," " no 
colour," etc. 

4. The Content of Free Fatty Acids in the case of fresh animal fats is 
fairly small. Foreign tallows frequently contain 20 per cent, or more of 
free fatty acids. In palm oil the free fatty acids often much exceed this 
figure. The amount of free fatty acid is ascertained by determining 
the acid value (see p. 122). 

5. The Yield of Solid Fatty Acids obtainable from tallow by lime 
saponification may be ascertained with the help of an empirical Table 
compiled by Dalican.- For technical purposes a separate Table for each 
class of fats should be prepared by making mixtures of solid and liquid 
fatty acids similar to those obtained technically on a large scale, and 
determining the titre of the several mixtures of known composition. 
Dalican's Table is obviously inapplicable to candle material obtained by 
sulphuric acid saponification, and separate Tables must be prepared for 
this purpose.^ More accurate results are obtained in the case of 
saponification by water and lime (or magnesia) by determining the - 
iodine value and calculating it to oleic acid. This method is, however, 
unreliable when applied to candle material obtained by sulphuric acid 
hydrolysis or by the mixed process, as " iso-oleic " acid also absorbs 
iodine. 

6. The Yield of Glycerol is determined directly as described in the 
Section on " Oils, Fats, and Waxes" (p. 123). This determination is, 
however, generally superfluous, as it is sufficient to reckon on a yield of 
10 per cent, from neutral fat, and to deduct i per cent, for every 10 per 
cent, of fatty acids.* 

(6) Testing of Intermediate and Finished Products. 
The progress of hydrolysis is watched by determining the unchanged 
neutral fat from time to time. An average sample is taken, and in the 
case of the sulphuric acid saponification process, boiled with water, and 
in the case of the lime or magnesia saponification process with dilute 
sulphuric or hydrochloric acid, then allowed to cool, and the cake of 

1 Chem. Zeit., 1901, 25, 99. 

- Cf. Lewkowitsch, Chemical Technology, etc., vol. ii., p. 641. ^ Ihid., vol. iii., p. 184. 

■» Lewkowitsch, The Laboratory Companion to Fats and Oils Industries, Table 5, p. 13. 



STEARINE CANDLES Hi 

fat taken off and washed free from acid. The acid and saponification 
values are then determined. 

Exa7nple. — If the saponification value, k, of a sample of tallow taken 
from the autoclave water process be 203, and the acid value, a, be 162-2, 
then k — a = 201—162-2 = A,o-Z corresponds to the amount of neutral fat 
present in the sample. As the saponification value of a neutral tallow 
is in round numbers 195, the proportion is : — 

195 : 100 = 40-8 \x. X = 20-92. 

The percentage of neutral fat in the sample is therefore 20-29, and 
the percentage of free fatty acids 100 — 20-92 = 79-08. 

The intermediate products are valued according to their solidifying 
points, and iodine values (with the above-mentioned limitation). 

As regards the Final Products, those obtained by the water, lime, 
and magnesia saponification processes are technically known as " saponi- 
fication " products, whilst those from the other processes are known as 
" distillation " products, since the fatty acids must always be purified by 
distillation. Hence in commerce, the terms saponification stearine, 
distillation stearine, saponification oleine, distillation oleine, saponifica- 
tion glycerin, and distillation glycerin are emplo}ed. 

The value of Saponification Stearine depends upon the solidifying 
point. The higher this is, the more valuable the candle material. A 
definite iodine value shows the quantity of residual oleic acid in the 
press cakes. A distinct difference between the neutralisation value and 
the saponification value corresponds to the quantity of neutral fat which 
has escaped saponification, and has not been pressed out with the oleic 
acid. For commercial purposes it is seldom necessary to estimate the 
quantities of palmitic and stearic acids separately. 

Distillation Steai'ine is also valued according to its solidifying point, 
which is generally lower than that of saponification stearine. The iodine 
value of a " distillation stearine " forms a measure of the quantity of 
"iso-oleic" acid present; the difference between the saponification 
value and the neutralisation value shows the amount of stearolactone 
present. 

A complete examination of distillation stearine comprises, therefore, 
the determination of the iodine value, the neutralisation value, and the 
saponification value, and the direct determination of the stearic acid. 
The palmitic acid is then found by difference. It is thus possible to 
distinguish between" saponification stearine "and "distillation stearine" 
by means of the iodine value. The iodine value of the former product 
seldom exceeds a few units, whereas distillation stearines give iodine 
values which lie for the most part between 1 5 and 30. 

A considerable amount of neutral fat is contained in the candle 
material used for the " composite candles," which consist of a mixture 
III M 



178 ANALYSIS IN OIL AND FAT INDUSTRIES 

of stearine and cocoa-nut stearine. If an accurate determination of the 
neutral fat is required, it is best to saponify 50 g. of the sample, and to 
estimate the quantity of glycerol obtained. 

Adulterants of "stearine" are solid hydrocarbons (paraffin wax, 
ceresin), distilled wool fat stearine, also carnaiiba wax, which is 
sometimes added to raise the solidifying point of the candle 
material. 

The presence of these substances is ascertained by the determination 
of the unsaponifiable matter. The unsaponifiable matter is examined 
as described in the previous Section (p. 139). In this manner paraffin 
wax, ceresin, and carnaiiba wax are detected. The presence of 
cholesterol indicates an addition of " distilled wool fat stearine." 

Candles consisting almost entirely of stearine are generally used in 
hot countries, as candles which contain much paraffin wax in addition 
to stearine are liable to bend and gutter, in consequence of their low 
melting point. 

In temperate climates, candles are generally made of mixtures of 
stearine and paraffin wax. 

Co))iuiercial Oleic Acid — Olcine — is a by-product, and is, as stated 
above, placed on the market in two qualities, " saponification oleine " 
and "distillation oleine." 

Saponification Oleine is generally dark in colour, and if it has not 
been freed from "stearine" by cooling, contains considerable quantities 
of solid fatty acids. Hence the iodine value of an oleine lies con- 
siderably below 90. All neutral fat which has escaped hydrolysis • 
in the autoclave process is present in this " oleine " ; its saponification 
value is therefore higher than its neutralisation value. All the un- 
saponifiable matter contained in the original fat is also present in the 
"oleine." 

Distillation Oleine obtained in the sulphuric acid saponification 
process or by the "mixed process" is a distillation product, and 
accordingly represents a bright, transparent oil. It contains, as a 
rule, small quantities of solid fatty acids, so that the iodine value of 
a distillation oleine, prepared commercially from tallow, lies between 
80 and 86. 

Before the method of distilling the fatty acids had reached its present 
state of perfection distilled oleines contained considerable quantities of 
hydrocarbons, which resulted from the decomposition of neutral fat 
remaining in the still. Hence it was formerly possible to distinguish 
" distillation oleine " from " saponification oleine " by the presence of 
hydrocarbons in the former. At present, however, owing to the 
improvements in the process of manufacture, the distillation oleine of 
commerce is {practically free from decomposition products. 

The other by-product. Glycerin, is treated in detail later (p. 198). 



PARAFFIN CANDLES 179 

2. Paraffin Candles (see also "Mineral Oils," p. 52). 

The chemical composition of paraffin wax is not yet definitely known, 
and varies with its origin. American paraffin wax may be considered as 
consisting of a mixture of hydrocarbons of the ethane series. The 
paraffin wax obtained in the lignite industry of Saxo-Thuringia 
contains a small percentage of olefines. Hence the iodine values of 
the paraffin waxes met with in commerce vary. Paraffin wax obtained 
from petroleum must not be taken to be identical with that obtained by 
destructive distillation. As a rule, the paraffin wax obtained by 
destructive distillation is superior to petroleum paraffin wax in its 
commercial application. 

Scotch crude paraffin wax is known in commerce under the name of 
" scale." This contains varying quantities of impurities, dirt, water, and 
hydrocarbons of lower melting point, which consist principally of "soft 
paraffin." The latter is commercially known in England as "oil," as it 
is valueless to the candle-maker. 

There is no definite dividing line between the solid hydrocarbons 
and the " oil," as the bard paraffin hydrocarbons pass by gradations 
through soft paraffin or lower melting paraffins to " oil." The quantity 
of oil which is pressed out in the manufacture depends naturally upon a 
number of conditions, such as temperature, pressure, length of time 
during which the pressure is applied to the mass, etc. It is therefore 
easily understood that a laboratory test for " oil " must be more or less 
empirical. 

For this reason special tests are laid down between the buyer and 
seller in specifications. 

The final product of the Scotch paraffin oil industry is sold as " Soft 
Paraffin " in case the melting point is below 48° (118° F.). Paraffin wax 
of melting point over 48°-9 (120" F.) is termed "Hard Paraffin." The 
candle material produced in the Saxo-Thuringian industry has, as a 
rule, a melting point of 53°-56° ; material of lower melting point (5o°-52°) 
or of higher melting point is but seldom placed on the market. 

Apart from colour, transparency, and smell, the most important 
characteristic in valuing paraffin wax is the melting point. The melting 
point and solidifying points coincide in the case of paraffin wax. A 
uniform method for the determination of the solidifying point of 
paraffin wax has not yet been agreed upon. The following three 
methods are met with in commerce, and are known respectively as 
(i) The English test; (2) The American test; and (3) The German 
test (Halle specification). 

I. TJie English Test. — A test tube of about i in. diameter is filled 
to a depth of 2 in. with molten paraffin wax. A small thermometer is 
immersed in the mass and the latter slowly stirred, so that the tube and 



180 ANALYSIS IN OIL AND FAT INDUSTRIES 

its contents cool gradually. The temperature at which the thermometer 
remains stationar\' for a short time is taken as the melting point. It is 
to be noted that the paraffin wax does not behave like a mixture of 
fatty acids, which exhibits a rise of temperature on solidifying. In 
the case of paraffin wax the mercury column remains stationar)' for 
about half a minute, but no sudden rise of the mercury takes place ; 
subsequently the mercury falls gradually. The stationary point is 
especially distinct when larger quantities — about 50 g. — are taken for 
the determination. 

2. The American Test. — A quantity of paraffin wax sufficient to fill 
a dish 3f in. in diameter three quarters full is melted. A thermometer 
with a round bulb is then immersed into the molten mass, so that only 
three-quarters of the bulb is in the paraffin wax. The wax is then 
allowed to cool gradually, and the temperature, at which the first sign of 
a film is seen to form from the wall of the dish across to the thermo- 
meter, is taken as the melting point 

3. The German Test. — A beaker about 7 cm. in height and 4 cm. in 
diameter filled with water is heated to about yo" , and a small lump of 
the sample is thrown on to the hot water, the lump being of such a size 
that after melting it spreads out to a disc of about 6 mm. diameter. 
As soon as the wax is liquid a thermometer of the special pattern pre- 
scribed by the " Verein fur Mineralolindustrie " is plunged into the liquid 
so that the horizontal mercury bulb of the thermometer is completely 
immersed. At the moment when the paraffin film forms a solid skin 
the solidifying point is read off on the thermometer. During this 
operation the beaker must be carefully protected from draughts by glass 
plates ; also, the paraffin layer must not be cooled by breath from the 
mouth. 

It is evident that the determination of the melting point by the 
American and German methods must lead to very uncertain results. 
It is therefore recommended to adopt the English method. 

Candles prepared exclusively from commercial paraffin wax are too 
soft and bend too easily ; it is therefore necessary to add from 3-15 per 
cent, of" stearine " to paraffin wax, according to its melting point. 

It has been already pointed out above (p. 173) that "stearine" is 
mixed with varying quantities of paraffin wax. The melting point of a 
mixture of stearine and paraffin wax cannot be calculated from the 
melting points of the components. It is, therefore, alwa\'s necessary for 
the control of the manufacture to construct an empirical Table for the 
special materials concerned. 

The following Tables of this character have been prepared by I. I. 
Redwood for mixtures of Scotch paraffin wax and "stearine," and 
by W. Scheithauer for mixtures of Saxo-Thuringian paraffin wax and 
" stearine." 



PARAFFIN CANDLES 



181 



Table 32. 

Melting Points of Candle Material from "Mixed Paraffin Wax" 

(Scotch Pyroparaffin) and "Stearine." (I. I. Redwood.) 



Paraffin wax. 



Per cent. 



90 
80 
70 
60 
50 
40 
30 
20 
10 



90 
80 
70 
60 
60 
40 
30 
20 
10 



90 
80 
70 
60 
50 
40 
30 
20 
10 



90 
80 
70 
60 
50 
40 
30 
20 
10 



90 
80 
70 
60 
50 
40 
30 
20 
10 



90 
80 
70 
60 
50 
40 
30 
20 
10 



Melting point. 



°F. 

102 
102 
102 
102 
102 
102 
102 
102 
102 



120 
120 
120 
120 
120 
120 
120 
120 
12'0 



120-25 
120-25 
120-25 
120-25 
120-25 
120-25 
120-25 
120-25 
120-25 



125 
125 

125 
125 
125 
125 
125 
125 
125 



130 
130 
130 
130 
130 
130 
130 
130 
130 



132-50 
132-50 
132-50 
132-50 
132-50 
132-50 
132-50 
132-50 
132-50 



"Stearine.' 



Per cent. 



10 
20 
30 
40 
50 
60 
70 
80 
90 



10 
20 
30 
40 
50 
60 
70 
80 
90 



10 
20 
30 
40 
50 
60 
70 
80 
90 



10 
20 
30 
40 
50 
60 
70 
80 
90 



10 
20 
30 
40 
50 
60 
70 
80 
90 



10 
20 
30 
40 
50 
60 
70 
80 
90 



Melting point. 



°F. 
121 
121 
121 

121 
121 
121 
121 
121 
121 



123 
123 
123 
123 
123 
123 
123 
123 
123 



129-75 
129-75 
129-75 
129-75 
129-75 
129-75 
129-75 
129-75 
129-75 



121 
121 
121 
121 
121 
121 
121 
121 
121 



121 
121 
121 
121 
121 
121 
121 
121 
121 



129-75 
]29-75 
129-75 
129-75 
129-75 
129-75 
129-75 
129-75 
129-75 



Mixture. 



Melting point. 



'F. 
100-0 

98-5 
100-0 
104-5 
110-5 
111-0 
113-5 
117-5 
119-0 



118-0 

116-50 

114-0 

112-0 

110-0 

109-0 

113-0 

118-50 

119-50 



118-50 

116-75 

114-50 

112-25 

113-0 

118-75 

122-0 

124-50 

127-0 



123 

121-0 

119-0 

117-50 

114-0 

111-0 

107-0 

114-0 

117-0 



1-28-0 

125-50 

123-0 

121-0 

118-50 

114-0 

109-0 

115-50 

118-0 



130-50 

128-50 

126-50 

124-25 

121-0 

117-75 

119-50 

125-25 

127-50 



182 



ANALYSIS IN OIL AND FAT INDUSTRIES 



Table 33. 

Melting Points of Candle Material from Saxo-Thuringian '• Paraffin 
Wax" and • Stearine" (W. Scheithauer.) 



ParafiQn wax. 


"Stearine." 


Mixture. 


Per cent. 


Helting point. 


Per cent. 


Melting point. 


Melting point. 




"C. 




-c. 


•c. 


90-0 


36-5 


10-0 




36-5 


66-6 
33-3 


33-3 
66-6 


54 


39-0 
45-75 


10-0 


90-0 




51-75 


90-0 


37-5 

J 


10-0 


'^ 


36-5 


66-6 
33-3 


33-3 
66-6 


54 


35-5 
47-0 


10-0 


90-0 


■ 


52-0 


90-0 


40-75 


10-0 


'1 

54 


39-75 


66-6 
33-3 


33-3 
66-6 


40-5 
47-5 


10-0 


90-0 


52-0 


90-0 


- 45-0 


10-0 


\ 


44-0 


66-6 
33-3 


33-3 
66-6 


54 


40-75 
48-0 


10-0 


90-0 




52-5 


90-0 


48-5 

J 


10-0 


y 54 


47-5 


66-6 
33-3 


33-3 
66-6 


45-0 
47-75 


10-0 


90-0 


52-5 


90-0 


> 


10-0 


54 


49-0 


66-6 
33-3 


I 50-0 


33-3 
66-6 


47-0 
47-5 


10-0 


J 


90-0 


52-5 


90-0 


54-0 


10-0 


54 

J 


53-0 


66-6 
33-3 


33-3 
66-6 


49-0 
47-0 


10-0 


90-0 


52-5 


90-0 




10-0 


\ 


55-5 


66-6 


33-3 


\ 54 


62-0 


33-3 


56*o 

* 


66-6 


47-5 


10-0 


90-0 


J 


52-5 



The proportion of stearic acid in paraffin candles is determined by 
dissolving 5-10 g. of the sample in petroleum spirit or ether, adding a 
few cubic centimetres of alcohol and titrating with normal alkali, using 
phenolphthalein as indicator. The number of cubic centimetres of 



WAX AND BEESWAX CANDLES 183 

alkali used is multiplied by 0-284 and divided by the weight of substance 
taken. 

3. Spermaceti Candles. 

Spermaceti candles are made of refined spermaceti. They are still 
used for lighting purposes, although they are, for the most part, super- 
seded by the cheaper stearine and paraffin candles. Until recently, 
spermaceti candles were always used as normal candles for photometric 
measurements in this country. 

Spermaceti alone cannot be used for candle-making, as it is too 
brittle ; hence beeswax, tallow, " stearine," paraffin wax, or ceresin is 
added. The standard spermaceti candles used for photometric work 
are only allowed to contain an addition of best air-bleached white 
beeswax of melting point 62° ; no other material is admissible, and the 
amount of beeswax allowed is between 3 and 4-5 per cent. The 
spermaceti itself must melt between 45° and 46°. 

The characteristics of spermaceti given in Table 27 of the Section 
on " Oils, Fats, and Waxes," p. 153, permit of the detection of adultera- 
tion with the above-named materials, 

4. Wax Candles, Beeswax Candles. 

The wax candles for use in churches in Russia, which account for a 
very considerable proportion of the total wax consumption of the world, 
must always be made of pure beeswax. The Catholic Church now 
allows for ritual purposes, church candles containing 75 per cent, 65 
per cent, and even less of beeswax.^ Hence, excepting the candles 
destined for Russia, very few "beeswax" candles are met with which do 
not contain admixtures. The commonest additions are stearic acid, 
tallow and rosin, spermaceti, and, above all, ceresin and paraffin wax. 
Vegetable waxes such as carnaiiba wax make beeswax practically 
worthless. Beeswax contains no glycerides ; in addition to free fatty 
acids of high molecular weight (much cerotic and little melissic acid), it 
consists chiefly of myricin (myricyl palmitate), free myricyl and ceryl 
alcohols, and, in addition, smaller quantities of hydrocarbons, and also 
some unsaturated acids. Crude beeswax has, as a rule, a yellow to 
reddish-brown colour. It has the pleasant smell of honey, a fine-grained 
structure, and is sufficiently soft at the ordinary temperature to be 
kneaded ; at lower temperatures it is brittle. It always contains 
imbedded grains of pollen which facilitate its microscopic detection. 
When purified by repeated melting over hot water and bleached by 
exposure to the sun or by chemical means, white wax is obtained. This 
is pure white or pale yellow, inodorous and tasteless, brittle and heavier 
than yellow wax, and generally shows a smooth fracture. 

1 Cf. Lewkovvitsch, Chemical Technology, etc., vol. iii., p. 337. 



184 ANALYSIS IN OIL AND FAT INDUSTRIES 

The most important characteristics of pure, yellow beeswax are 
given in Table 27, p. 153. It is, however, to be noted that these values 
do not hold for Indian waxes (" Ghedda wax"), which give abnormal 
values.^ "Ghedda" wax appears to differ from ordinary yellow 
beeswax in that it contains ceryl alcohol as the only alcoholic 
constituent. 

A preliminary indication of the purity of a wax is given by its 
melting point, specific gravity, and solubility in chloroform. 

The iodine value, which varies from 9- 11 in the case of pure 
yellow wax, whereas it is lower (about 4) for white wax, may afford 
further information in cases of doubt. 

The most important characteristics in the examination of pure 
beeswax are the acid and saponification values. The acid value of 
yellow wax is from 18-22 (as a rule 19-20); the saponification value is 
88-99, hence the difference between the acid value and the saponification 
value is 69-79. (This difference was termed by Hiibl the " ether value " ; 
the author avoids this term, as it is somewhat misleading.) As the 
higher and lower values frequently occur together, the quotient : — 

saponification value — acid value 
acid value 

i.e. " Hiibl's ratio value," varies within narrow limits, namely, between 
3-6 and 3-8. For white wax the limits must be somewhat extended, 
namely, for the 

Acid value ..... to i9-7o-24-oo 
Saponification value . . . „ 93-6o-io7-oo 

Hiibl's ratio value . . . . „ 2-96-3-97 

The method of determining the saponification value is practically 
the same as for fats (p. 114), modified, however, by the fact that the 
esters of beeswax, as also its more frequently used adulterants (paraffin, 
ceresin), are almost insoluble in alcohol. Since these form a protective 
coating round the soluble portions, and thus inhibit the action of the 
alkali, incorrect results ,may be obtained unless the saponification be 
carried out as described below. 

For the determination of the acid value, 3-5 g. of beeswax are 
warmed for some time with 25 c.c. of 95 per cent, alcohol, and the free 
acid then titrated with Nji alkali, using phenolphthalein as indicator. 
The saponification value is determined on a separate quantity of 1-5-2 
g. with 25 c.c. of an A72 alcoholic solution of potassium hydroxide 
prepared with strongest (almost absolute) alcohol. The boiling must 
be continued over a wire gauze and under a reflux condenser for at 
least an hour, as the saponification is otherwise incomplete. 

If the main problem be to ascertain the purity of a beeswax, it is 
' C/. Lewkowitsch, Chemical Technology, etc., vol. ii., p. 755. 



WAX AND BEESWAX CANDLES 



185 



sufficient to determine the acid and saponification values. If these 
give normal values the specific gravity is determined, and further, 
ceresin and paraffin wax are tested for by Weinwurm's method (see 
p. 1 86). If these hydrocarbons are absent and the specific gravity lies 
within the limits given above, the sample may be pure. The melting 
point and also the iodine value should, however, be determined as well. 
The following Table gives the characteristics of pure beeswax and 
of the usual adulterants found in it (average values) : — 



Table 34. 
Characteristics of Beeswax and of the usual Adulterants found in it. 





Acid value. 


Saponiflcation 
value. 


Ratio value. 


Beeswax (yellow) 
„ (white) . 
Carnatiba wax 
Chinese (insect) wax . 
Japan wax . ... 
Myrtle wax .... 
Spermaceti ..... 
Tallow and tallow stearine . 
Stearic acid (commercial) 
Rosin ..... 
Paraffin wax and ceresin * . 


19 to 21 

19-7 „ 24 

2 



20 

3 



4 to 10 

200 

130 to 164-6 




91 to 97 
93-5 „ 107 
80 
80-4 
227 
208 
130 
195 
200 
146-8 to 194 



3-62 to 3-84 

2-96 „ 3-97 

39 

lb -8 
68-3 

18-5 to 48 

0-126 to 0-191 




* Commercial paraffin and ceresin are not always quite free from acid. 

From these data the following conclusions may be drawn : — If the 
saponification value of a sample is below 92 and at the same time the 
" ratio value " equal to that of a pure wax, paraffin wax or ceresin is 
present. 

If the "ratio value" exceeds 3-8, adulteration with tallow, Japan 
wax, spermaceti, or other waxes is probable. If, at the same time, the 
acid value is below 20, Japan wax is excluded. An abnormally low 
" ratio value " (high acid value) leads to the conclusion that stearic acid 
or rosin (colophony) is present. The values quoted in the Table show, 
however, that more complicated adulterations are possible by the 
simultaneous addition of several adulterants. Their presence cannot 
be recognised readily by the test just mentioned. Thus, the addition 
of a mixture of 37-5 per cent, of Japan wax, 6-5 per cent, of stearic acid, 
and 56 per cent, of ceresin, a mixture containing no beeswax whatever, 
furnishes perfectly "normal" values. In such cases the adulteration 
can be detected, not only by the appearance of the sample (fracture, 
taste), but also by the following tests : — 

Detection of Glycerides. — If 20 g. of the sample are saponified and 
tested for glycerol, a positive result indicates the presence of fats (Japan 
wax, tallow). 



18G ANALYSIS IN OIL AND FAT INDUSTRIES 

Detection of Stearic Acid. — Stearic acid is more readily soluble in 
alcohol than the free cerotic acid occurring in beeswax. Hence if i g. 
of wax be boiled with lo c.c. of alcohol of 80 per cent, by volume, 
allowed to cool, filtered, and water added to the filtrate, the liquid 
becomes only slightly turbid in the case of pure wax, whilst any stearic 
acid present separates in flocks ; as little as i per cent, of stearic acid 
can be thus detected. 

It is, however, to be borne in mind that if rosin is also present, this 
also dissolves and gives an emulsion with water.^ 

Detection of Rosin. — The presence of rosin in beeswax is easily 
recognised by its taste and stickiness. In contrast to pure beeswax it 
adheres to the teeth when chewed. To detect rosin the Liebermann- 
Storch reaction (p. 130) is used; its quantitative determination is 
carried out by Twitchell's method (p. 195). 

Detection of Ceresin and Paraffin Wax. S. Weinwurm's Test.- — 5 g. 
of beeswax are saponified with 25 c.c. of N/2 alcoholic potash, the 
alcohol evaporated off, 20 c.c. of concentrated glycerol added, and the 
solution heated further until all is dissolved. On adding 100 c.c. of 
boiling water, genuine beeswax gives a more or less clear, transparent 
to translucent solution. If a paper printed with letters of normal size 
is placed under the vessel the printing must be perfectly legible. If, on 
the other hand, the wax contain 5 per cent, or more of ceresin or 
paraffin wax, a turbid solution or a precipitate is obtained which makes 
the printing illegible. If the turbidity is but slight, about 3 per cent, 
of ceresin may be present. To detect this, a second test is made, 3 per, 
cent, of ceresin being added to the wax before saponification. If a 
decided turbidity is now obtained, then small quantities of foreign 
hydrocarbons must have been originally present; if the turbidity is not 
more distinctly marked, the presence of hydrocarbons is not proved. 
In presence of 8 per cent, of ceresin or paraffin wax a precipitate is 
obtained. 

It must, however, be borne in mind that this test is only of a 
preliminary character. Moreover, a turbidity does not necessarily 
point to the presence of paraffin wax and ceresin, for a beeswax to 
which 50 per cent, of carnaiiba wax or insect wax has been added gives 
(as the author has shown) just as great a turbidity as one containing 
5 per cent, of paraffin wax. 

For the quantitative estimation of ceresin or (and) paraffin wax, the 
following method of A. and P. Buisine-^ is recommended: — 2-10 g. of 
the sample are melted in a small porcelain crucible, the same weight of 

1 For a method of detection proposed by Buchner and criticised by Berg, c/. Lewkowitsch, 
Chemical Techtiology, etc.^ vol. ii., p. 770. 

2 Chem. Zeit., 1897, 21, 519 ; /. Soc. Chem. hid., 1897, 16, 939. 

3 Monit. Scient., 1890, Scr. [iv.], 4, 1 134. 



WAX AND BEESWAX CANDLES 187 

finely powdered potassium hydroxide added, and the whole stirred. 
The hard mass resulting on cooling is powdered and intimately mixed 
with 3 parts of potash lime for i part of wax, (The potash lime is 
prepared from i part of potassium hydroxide and 2 parts of lime.) The 
mixture is placed in a test tube or a small pear-shaped flask and heated 
in a mercury bath, the temperature being maintained for two hours at 
250°. The bath consists of an iron vessel with an air-tight cover 
having three openings ; in one of these the small flask is fixed, in the 
second a thermometer, whilst in the third a long iron tube is fitted, to 
condense the mercury vapour. After cooling, the melt is powdered, 
extracted with dry ether, the extract filtered, the ether distilled off, 
and the residue (if necessary after a second treatment with ether and 
filtering) dried and weighed. The proportion of hydrocarbons in yellow 
beeswax varies from I2-5-I4-5 per cent. (Hett and Ahrens found up to 
I7'35 P^r cent.). An addition of 3-5 per cent, of ceresin or paraflin 
wax can thus be detected with certainty, 

Detectio7i of Carnailba Wax. — An addition of carnaiaba wax raises 
the specific gravity and the melting point. Carnaiiba wax is not 
completely soluble in chloroform, in contradistinction to pure yellow 
wax. Weinwurm's test also serves as a good preliminary test. An 
incontrovertible proof of the presence of carnaiiba wax is a difficult 
problem, and its quantitative determination still more so ; these can 
only be effected by an exhaustive examination of both the free and 
combined fatty acids. This applies also to the detection of insect wax. 

For the detection of the several ingredients of a white wax candle 
consisting of a mixture of bleached beeswax, spermaceti, stearic acid, 
paraffin (and) or ceresin, and for the detection of adulterants, cf. J. 
Lewkowitsch, Chemical Technology, etc., vol, ii., p. yyG, and vol. iii., 

P- 335- 

5. Ceresin. 

Ceresin is the product obtained by refining ozokerite (earth wax), 
a natural bituminous product, found mostly in the neighbourhood of 
petroleum springs. The richest pockets of ozokerite are at present 
found in Galicia, The refined ceresin varies in colour from dark orange 
yellow to almost pure white. It has a specific gravity of 0-9 18-0-922, 
melts at 6i°-'j2>'' (higher than paraffin wax), has a conchoidal fracture, 
and is not crystalline. Pure specimens are odourless. It is largely 
adulterated with paraffin wax and with rosin. Additions of carnaiiba 
wax for the purpose of raising the melting point are also made 
sometimes. 

The melting point of ceresin is much lowered by the addition 
of considerable quantities of paraffin wax. For technical purposes the 
melting point is still frequently determined by Pohl's method which is 
stipulated in specifications. The accuracy of this method has been 



188 ANALYSIS IN OIL AND FAT INDUSTRIES 

improved by employing Ubbelohde's apparatus {cf. " Oils, Fats, and 
Waxes," p. 108). 

For the detection of paraffin wax in ceresin, J. Marcusson and H. 
Schliiter^ have recommended a method which is said to give approxi- 
mately correct results under certain conditions, but which, at present, 
stands in need of confirmation. 

Ceresin containing rosin has a definite acid value. Unadulterated 
ceresins are, however, met with which contain a small proportion of acid, 
owing to the sulphuric acid used in the refining process (acid value up 
to 4), but samples adulterated with rosin show much higher acid values. 
Rosin is detected and estimated in the alcoholic extract as described on 
p. 186. 

Z.— SOAP. 

Salts of fatty acids are termed soaps. A differentiation is made 
between salts of alkali metals on the one hand, and salts of the alkaline 
earths and heavy metals on the other. In commerce, the term "soap" 
refers only to the alkali salts of the non-volatile fatty acids. According 
as the base is soda or potash the products are distinguished as hard 
soaps (soda soaps) and soft soaps (potash soaps, soft soap). These 
soaps are also termed soluble soaps. 

The salts of the alkaline earths and heavy metals are also termed 
metallic soaps, or water-insoluble soaps {cf. infra). 

Soda Soaps. 

These are prepared on the large scale by two methods — (i) b\- the 
so-called cold process ; (2) by the boiling process (hot process). 

For the manufacture by the former process, the vegetable fats of the 
cocoa-nut oil group are especially suitable. For their saponification, 
concentrated solutions of caustic soda must be used. With the help of 
these fats, other fats which are in themselves not readily hydrolysed by 
concentrated caustic soda (such as olive oil, tallow, lard) may be 
saponified in the cold. The " cold-made " soaps which thus result contain, 
of course, all the glycerin, and any salts present as impurities in the 
caustic soda, and frequently also free alkali, and even unsaponified fat. 

Theoretically, a soap prepared from cocoa-nut oil or palm kernel oil 
has the following composition : — 

Fatty acid anhydrides 

Sodium o.xide (Na^.O) .... 

Water and glycerol (by difference) . 

loO'Oo per cent. 
" Filling " materials are frequently added to these soaps. 

' Cliem. Zeit.^ 1907, 31, 348 ; /. Soc. Clum. J>uL, 1907, 26, 491. 



54-50 


per 


cent, 


8-86 




)» 


36-64 




5) 



SOAP 189 

The soaps prepared by the second method (boiling process) are 
obtained either by boiling mixtures of neutral oils and fats with caustic 
soda solution, or by boiling " fatty acids," which are manufactured on a 
large scale, with sodium carbonate and caustic soda. A third process 
depending upon the double decomposition of lime soap with soda ash 
is in use in a few small soap factories on the Continent. The soap 
paste obtained in the boiling process is " salted out" with common salt; 
the curd is again boiled to a paste, and then converted into pressed 
soap, which solidifies on cooling to a solid mass, so that it can be cut up 
into the well-known soap bars and cakes. The glycerol of the neutral 
fats passes into the soap lye. Such soaps cannot be prepared with a 
higher proportion of fatty acids than 63-64 per cent. The theoretical 
composition (taking the mean molecular weight of the fatty acids as 
275) is as follows : — 

Fatty acid anhydrides . . . 61 -So per cent. 

Sodium oxide (Na^O) .... 7-21 ,, 

Water and glycerol (by difference) . . 30-99 „ 

loo-oo per cent. 

If it be desired to prepare soaps with a smaller percentage of water, 
as in the manufacture of milled toilet soaps, the curd must be deprived of 
part of its water (" water of constitution "). If, on the other hand, a 
higher proportion of water be desired, additions of solutions of silicate 
of soda, soda ash, sodium sulphate, common salt, etc., are made, either 
in the soap pan itself, or in special mixing machines. These " run " soaps 
represent the cheap household soaps ; their proportion of fatty acids 
may be reduced by " filling" to as little as 12-16 per cent. 

Further varieties of soda soaps are : — 

1. Transparent Soaps, made either by dissolving the soap in alcohol, 
distilling off the alcohol, and moulding the gelatinous residue, thus yield- 
ing soaps containing a high percentage of fatty acid, or (cheap) " filled " 
soaps, rendered transparent by the addition of sugar solution. 

2. Soap Powders, Washiiig Powders, " Dry Soap" which are prepared 
by grinding soda soaps with soda, etc. 

Potash Soaps (Soft Soap). 

These are made by boiling neutral fats or commercial " fatty acids " 
with solutions of caustic potash, or a mixture of this with potassium 
carbonate. These soaps are not salted out, and hence the soft soaps 
contain, like the "cold-made" soda soaps, all the glycerol contained in 
the neutral fat, together with the excess of alkali, the potassium 
carbonate, and any "filling" material which may have been added. 
Normal soft soaps cannot be obtained in the soap pan with more than 
about 40 per cent, of fatty acids. Hence the theoretical composition of 



190 ANALYSIS IN OIL AND FAT INDUSTRIES 

a soft soap made from neutral fats or " fatty acids," assuming a mean 
molecular weight of 275 for the fatty acids, is as follows : — 

Fatty acid anhydrides . . . 38-70 per cent. 

Potassium oxide (K.,0) . . . 6-84 „ 

Water and glycerol (by difference) . . 54-46 



» 



100-00 per cent. 

Potash soaps are frequently '* filled," so that the proportion of 
fatty acid in commercial products falls to 25 per cent, and less. 
Frequently rosin is introduced, so that the isolated fatty acids include 
the rosin acids. The latter are estimated by Twitchell's method 

(P- 195). 

The number of substances which are openly added to soaps, to 

impart to them some useful (real or supposed) property, is enormous. 

It must be left to the analyst to decide in each individual case whether 

petroleum, paraffin wax, tar oil, sulphur, etc., are to be regarded as 

adulterants or not. 

In the present state of the soap industry, and in view of the require- 
ments of the consumer, it is difficult to say what constitutes 
Adulteration. 

Rosin (colophony) is a legitimate substitute for fatty acids, as the 
alkali salts of the rosin acids possess washing properties. Hence rosin 
acids, which are obtained on decomposing a soap with mineral acid, are 
generally reckoned together with the fatt}' acids and returned as fatty 
acids. 

Silicate and borate also possess washing properties ; these substances 
must, however, be considered as standing on the border line between 
legitimate ingredients and adulterants. 

Dyes in soaps must not be considered as illegitimate additions, as 
there is a demand for coloured soaps. Provided that the colouring 
matter is harmless, no objection need be raised against such an 
addition. At the most, the analyst will have to determine whether the 
colouring matter contains poisonous metals or not. 

Essential Oils in soaps have become almost a necessity. The 
quantity contained is generally very small, and, as a rule, such 
ingredients do not come within the scope of the analytical examination. 

There can, however, be no doubt as to adulteration having taken 
place when filling materials or "weighting substances" arc found in a 
soap. Starch, clay, talcum, sand, etc., fall under this category. 
Naturally, the sand found in a " sand soap," sold as such, cannot be 
looked upon as an adulterant. 

Raw Materials. 
The raw materials of the soap industry arc the neutral fats and 



SOAP 191 

" fatty acids," which are examined by the methods described in the 
foregoing Section. In the " fatty acids " the quantity of neutral fat and 
fatty acids is determined {cf. p. 177). 

In the following paragraphs the most reliable methods (omitting a 
large number of suggestions) for the testing and valuation of commercial 
soaps are given. The author has made no attempt to give a general 
and complete system for ths analysis of soaps which would include 
every possible ingredient, as such a procedure would have but little 
value. 

Sampling. — In sampling great care must be taken to avoid 
errors in the determination of moisture. By exposure to the air soap 
dries on the surface, and as soon as a "skin" has formed on the outer 
surface of a hard soap the interior is protected against further evapora- 
tion. Therefore, in the case of hard soaps the samples for analysis 
must be taken from the middle of the piece, the skin being cut away ; 
an inspection of the sample will generally indicate how much must be 
cut away, as a transverse section shows to what depth the drying has 
progressed. Suggestions to take a sample by means of a cork borer or 
by cutting out a transverse section, so as to obtain an " average sample," 
lead to incorrect results. If the sample to be tested is fresh, thus contain- 
ing at least 30 per cent, of water, a somewhat large quantity is quickly 
weighed out (as soap readily loses water in the dry air of a balance 
case). For the same reason, the sample should not be sliced before 
weighing ; at most, this is permissible only in the case of a milled or of 
a dried soap. 

In such cases the well-known devices to prevent loss of water during 
weighing must be employed. 

Similar precautions must be observed in sampling soft soaps. The 
sample must be taken from the middle of the soap. 

(a) Determination of the Fatty Matter and Total Alkali. 

A rapid method, sufficiently accurate for commercial purposes, is the 
following : — 5-10 g. of the sample (or 50 g. weighed on a balance which 
indicates correctly to centigrams) are accurately weighed out, and 
dissolved in hot water in a beaker or a porcelain dish, the liquid being 
stirred constantly with a glass rod to prevent the caking of the soap at 
the bottom of the vessel. After adding a few drops of methyl orange 
an excess of standard sulphuric acid (or in case chlorides and sulphates 
are to be determined, dilute nitric acid) is added, and the liquid heated, 
with constant stirring, until the separated fatty acids have liquefied. 
About 5 g. (or 20 g. for 50 g. of soap) of dry beeswax or paraffin wax, 
weighed accurately in a tared watch-glass (which is afterwards used for 
weighing the fatty matter), are added, and the liquid again heated until 
the mixture of fatty acids and wax has separated on the surface of the 



192 ANALYSIS IN OIL AND FAT INDUSTRIES 

aqueous layer as a clear, transparent layer of oil, free from solid particles. 
(If it be known that the fatty acids solidify to a hard mass, the addition 
of wax, etc., is, of course, superfluous.) The glass rod is rinsed with hot 
water, and the liquid again heated until the fatty substance forms a 
uniform mass. The source of heat is then removed and the vessel allowed 
to cool. Any white precipitate found on the bottom of the vessel 
indicates the presence of silicate or of " filling " materials, which are 
insoluble in mineral acid. 

The solidified cake of fatty matter is lifted off by means of a 
platinum spatula, rinsed with cold water, and placed on filter paper. 
Any remnant of fatty matter adhering to the walls of the vessel are 
carefully scraped off and added to the main portion. The cake is dried 
with filter paper and brought on to the same watch-glass which was 
used before, bottom side upwards, and allowed to dry in a desiccator 
and weighed. (For the control of the manufacturing process, for which 
purposes 50 g. should be taken, it is sufficiently accurate to weigh at 
once after drying with filter paper, but care must be taken that all water 
present in crevices of the cake are removed by filter paper.) If the cake 
has crevices enclosing water and perhaps even acid, which occurs only 
when the mass has not been heated sufficiently long, the cake must be 
melted over water, allowed to solidify, and again treated as before. 

The weight of the beeswax or paraffin wax is deducted from 
the weight thus found, and the difference is reckoned as fatty matter; 
when no further examination is required, it is generally returned 
as fatty acids ; this is, however, only correct if the absence of neutral 
fat, wax, and unsaponifiable matter has been proved. Rosin acids are 
included in the fatty acids, except in cases where a separate deter- 
mination of rosin acids is required. The acid liquid is filtered, 
the excess of mineral acid titrated back with standardised alkali, and 
the total alkalinity thus found. 

Any soluble fatt)' acids present in the soap pass to some extent 
into the acid liquid ; as a rule they are neglected, except when cocoa- 
nut oil or palm kernel oil soaps are under examination. In such cases 
it is best to work with concentrated solutions, or, if permissible, to add 
common salt, which renders the bulk of these acids insoluble, so that 
the dissolved portion may be neglected. If great accuracy is required, 
the soap is decomposed under ether ; all the fatty acids are thus 
obtained in ethereal solution as they are liberated. A less accurate 
method is to titrate the aqueous solution to neutralit)- with methyl 
orange, then to add phenolphthalein, and to titrate again with Njio 
alkali. In this case the alkali used for the second titration is calculated 
to caprylic acid, CyH^^O.^, molecular weight 144, and the amount thus 
found is added to the main portion of the fatt\' acids. 

A considerable number of methods supposed to increase the 



SOAP 193 

accuracy of the determination have been suggested. In the author's 
opinion, however, they only comph'cate the analysis without offering any 
advantage. 

If the absence of neutral fat, wax, and unsaponifiable matter (p. 196) 
has been proved, the fatty material is returned as fatty acids. In 
a complete soap analysis this amount is multiplied by 0-9675 to convert 
it to anhydride. 

The higher the percentage of fatty acids, the more actual soap is 
present. A comparison of the analytical results with the theoretical 
compositions of soaps given above will furnish a useful guide in the 
valuation of a sample, 

(b) Combined Alkali, Free Caustic Alkali, and Alkaline Salts. 

Free Fatty Acids. 

The total alkali is the sum of the several amounts of alkali present 
in the soap, as (i) alkali combined with fatty and rosin acids termed 
"combined alkali"; (2) free caustic alkali; (3) alkali as carbonate, 
silicate, or borate. 

1. The Combined Alkali is generally found by difference, ie. by 
subtracting the sum of the amounts of alkali found under (2) and (3) 
from the total alkali. It can, however, be determined directly by 
titrating the alcoholic solution with methyl orange, after having made it 
neutral to phenolphthalein. This may be done as a check, or to avoid 
the separate determination of alkali present as carbonate, silicate, 
or borate, as the latter can then, of course, be determined by difference, 

2. Free Caustic Alkali. — A preliminary test is first made by 
placing a drop of phenolphthalein on to a freshly cut surface of the 
soap. A red colour indicates the presence of free sodium hydroxide; 
if the soap is moist the red colour may be produced also by carbonate, 
silicate, or borate, but if it has been dried these salts produce no colora- 
tion. In order to separate the free caustic alkali from alkaline salts, 
part of the sample is dissolved in absolute alcohol and filtered. The 
alkaline salts remain on the filter, so that the alcoholic filtrate can then 
be tested with phenolphthalein. 

Soaps which have been properly manufactured should not contain 
free alkali ; this holds especially for toilet soaps. As great care 
and experience are necessary in the process of " filling," in order 
to produce a soap practically free from excess of alkali, most commercial 
soaps, especially household soaps, contain an excess of free alkali. If 
this quantity be very small, the free alkali becomes converted to 
carbonate by exposure to the air, so that in some cases no free 
alkali is found, especially if the outer layer only is tested. 

Free caustic alkali is estimated quantitatively^ by dissolving 10-30 g. 

1 Hope, C/ietn. News, 1 88 1, 43, 219, 
III N 



194 ANALYSIS IN OIL AND FAT INDUSTRIES 

of the sample in hot absolute alcohol in a loosely closed flask (to 
avoid the absorption of atmospheric moisture). Soaps containing much 
moisture must be partially freed from water, care being taken to exclude 
air, to avoid absorption of carbon dioxide. The hot solution is rapidly 
filtered, so that the soap does not separate out as a gelatinous mass on 
the filter ; when the operation is carried out with care, a hot-water funnel 
is unnecessary. The filter is washed with absolute alcohol and the 
filtrate collected in a flask. Phenolphthalein is then added, and the 
solution titrated with A710 hydrochloric acid. 

In some cases the alcoholic soap solution may react acid to 
phenolphthalein. This is due to the presence of an acid salt (distearate, 
dipalmitate, dioleate), in consequence of faulty fitting, or also to 
intentional addition of fatty acids to the soap with the object of 
neutralising the free alkali. The quantity of Njio alkali necessary to 
neutralise the solution is calculated to free fatty acids in terms of oleic 
acid. 

3. Carbonate, Silicate, and Borate. — The residue remaining on 
the filter consists of carbonate, silicate, and borate, together with other 
insoluble substances added as filling materials, such as starch, talcum, 
dyes, etc. (For a complete examination of this residue, see p. 197). 
For the determination of the alkali contained in the alkaline salts, the 
residue is washed on the filter with cold water {cf. (e) i, p. 197). The 
alkali in the filtrate is determined by titration with normal acid, using 
methyl orange as the indicator, and is calculated to Na.^O. 

(c) Determination of Water. 

The direct determination of water in a soap is, as a rule, unnecessary. 
In the case of genuine soaps it is sufficient for all practical purposes to 
calculate the fatty acids to anhydrides and to add the quantity of alkali 
found in the several forms ; the water is then found by difference. 

The direct determination of water is therefore carried out only in 
exceptional cases. For this purpose the soap is introduced in thin 
shavings into a porcelain dish, weighed with a glass rod, so that from 
time to time the dry skin, which prevents the evaporation of water from 
the interior layers, can be broken. This is especially necessary in the 
case of highly " run " soaps. 

For the valuation of a sample of soap it is generally sufticient to 
carry out tests (a) to (c). Further tests include the examination of the 
fatty matter and the detection and estimation of other ingredients of 
the sample. 

(</) Examination of Fatty Matter ("Soap Stock")- 

Assuming no wax, etc., has been used in the separation of the fatty 
matter, this can be used at once for further examination. The fatty 



SOAP 195 

matter may contain in addition to fatty acids: i. Rosin acids; 
2. Neutral fat ; 3. Unsaponifiable matter. 

I. Rosin Acids- — These are determined by Twitchell's method/ as 
the author has shown that the older methods proposed by Barfoed and 
Gladding and others, and the modifications of these methods, give 
unreliable results. 

E. Twitchell's method depends upon the property of the aliphatic 
acids that they are converted into esters by treatment with hydrogen 
chloride gas in alcoholic solution, whereas rosin acids under the same 
treatment undergo only a very slight alteration, abietic acid separating 
from the solution. 

For the determination, 2-3 g. of the mixed fatty and rosin acids are 
weighed out accurately in a flask and dissolved in ten times their 
quantity of absolute alcohol. The use of absolute alcohol is indispens- 
able, as esterification is incomplete in 90 per cent, alcohol. The flask 
is immersed in cold water, and a current of dry hydrogen chloride is 
passed through the liquid. After about three-quarters of an hour, 
when the gas is passing through the liquid unabsorbed, the operation 
is finished. In order to achieve as complete esterification as possible, 
the flask is allowed to stand for an hour. During this time the ethyl 
esters and the rosin acids rise to the surface as an oily layer. The 
contents of the flask are diluted with 5 vols, of water, and heated until 
the aqueous solution has become clear. The analysis can then be 
completed either volumetrically or gravimetrically. 

(a) Volumetric Method. — The contents of the flask are transferred 
to a separating funnel, and the flask rinsed out several times with ether. 
After shaking well the acid layer is drawn off, and the ethereal solution, 
which contains the ethyl esters of the fatty acids and the unchanged 
rosin acids, is washed with water until the hydrochloric acid is 
completely removed. Then 50 c.c. of alcohol are added to the 
solution, and it is titrated with normal alkali, phenolphthalein being 
used as the indicator. The rosin acids combine at once with the 
alkali, whilst the ethyl esters remain almost unchanged. The combin- 
ing weight of the rosin acids is taken as 346 ; thus the number of 
cubic centimetres of normal alkali used in the titration multiplied by 
0-346 gives the quantity of rosin acids in the sample. 

(b) Gravimetric Method. — The contents of the flask are mixed with 
some petroleum spirit boiling below 80°, and transferred to a separating 
funnel, the flask being rinsed out with petroleum spirit. The petroleum 
layer should amount to about 50 c.c. After shaking, the acid solution 
is drawn off, the petroleum layer washed once with water, the water 
drawn off, and 50 c.c. of an aqueous solution of potassium hydroxide 
containing 0-5 g. of potassium hydroxide and 5 c.c. of alcohol are added. 

' J. Anal, and Applied Cheni., 1891, 5, 379 ; J. Soc. Chem. Ind., 1891, 10, 804. 



196 ANALYSIS IN OIL AND FAT INDUSTRIES 

The rosin acids are extracted by the dilute alkahne solution, forming 
soaps, whilst the ethyl esters still dissolved in the petroleum spirit float 
on the surface. The soap solution is drawn off, decomposed with 
hydrochloric acid, and the separated rosin acids are weighed, cither 
directly on the filter, or preferably after extraction with ether and 
evaporation of the ether. The residue gives the quantity of rosin acids 
present in the sample. 

Of all the methods hitherto proposed for the estimation of rosin 
acids, Twitchell's method gives the best results. These must not, 
however, be considered as strictly accurate, as the author has shown in 
an exhaustive investigation of the volumetric and gravimetric methods 
that the results are only approximate.^ 

2. Neutral Fat. — A properly manufactured soap will seldom 
contain unsaponifiable fat. In case neutral fatty matter has been 
purposely added to the finished soap, as in the case of " superfatted " 
soaps (olive oil, or, in certain toilet soaps, wool wax), it is obtained 
together with the unsaponifiable matter. The neutral fat must then be 
separated from the unsaponifiable matter. 

The neutral fat plus unsaponifiable matter can be obtained directly 
from the sample by dissolving a weighed quantity in water or alcohol, 
titrating with normal alkali in the presence of phenolphthalein to 
neutralise any free fatty acids, and then extracting the soap solution as 
described in the Section on " Oils, Fats, and Waxes," p. 124. 

The residue of the ethereal solution consists of neutral fat plus 
unsaponifiable matter. The separation of the two components is 
effected by saponifying and extracting again with ether. 

If no unsaponifiable matter be present, the ether residue consists 
essentially of neutral fat ; otherwise the neutral fat is found by 
difference, or it may also be ascertained directly by isolating the fatty 
acids and calculating the quantity found to glycerides. 

A complication occurs when the soap contains wool wax. If this 
ingredient is suspected, the ether residue must be saponified with dilute 
alcoholic potash on the water-bath, in order to obtain at least a portion 
of the wool wax in the form of unsaponifiable matter, which can then be 
examined and irlcntified. 

3. Unsaponifiable Matter. — This is determined together with the 
neutral fat, as described. In case no neutral fat be found, the whole of 
the ether residue is taken as unsaponifiable matter. This is examined 
as described in the Section on " Oils, Fats, and Waxes," p. 139. 

Besides the substances given on p. 139, the possibility of the 
presence of vaselin, petroleum hydrocarbons, naphthalene, parafifin wax, 
wool-fat hydrocarbons, etc., must be taken into account. 

The examination of the fatty acids themselves (after separating the 

' J. Soc. Chein. Ind., 1 893, 12, 504. 



SOAP 197 

rosin acids, neutral fat, and unsaponifiable matter) is also carried out as 
described in the Section on " Oils, Fats, and Waxes." 

(e) Substances Insoluble in Alcohol. 

The determination of all the substances which are insoluble in 
alcohol is conveniently combined with the estimation of free caustic 
alkali (p. 193), the insoluble residue being collected on a previously 
dried (at 100') and weighed filter, and then weighed after again drying 
at 100°. 

Good soaps generally give a negligible residue. Only the toilet 
soaps prepared by the " alcohol process " are quite free from insoluble 
substances. 

The residue on the filter may consist of: — 

1. Water-soluble substances, such as chloride, sulphate, carbonate, 
silicate, and borate of the alkali metals. 

2. Mineral substances insoluble in water, such as colouring matters, 
*' filling " and " weighting " materials such as talcum, etc. 

3. Organic substances, especially starch, dextrin, gelatin (Carragheen 
mucilage). 

1. Water-soluble Substances. — The residue on the filter is washed 
with f^/(a^ water, so that any gelatin present does not pass into solution. 
The presence of silicate will have been already detected in the deter- 
mination of the fatty matter when decomposing the soap by acid (see 
above under (a)). The silica can be determined at this stage, assuming 
that no other substances insoluble in water are present, by acidifying 
the filtrate with hydrochloric acid, after determining the total alkali by 
titration (see (d) 3) and evaporating to dryness in the usual way. The 
filtrate from the precipitated silica can be examined for boric acid. 

In case boric acid is absent, carbonate and silicate may be found 
from the total alkali as estimated by titration, and the silica as found by 
weighing. If boric acid is also present and its quantity is to be 
determined, it is best to divide the solution into three parts. In the 
first the carbonic acid is determined, in the second the silica, and in the 
third the total alkali by titration. 

Chlorides and sulphates are best determined in aliquot parts of the 
acid liquid obtained after separating the fatty matter as described under 
(a). In this case, as stated above, nitric acid must be used for the 
decomposition of the soap. 

2. Substances Insoluble in Water are incinerated to remove 
organic matter, and the residue weighed. The ash is examined 
qualitatively and quantitatively in the usual way. 

3. Organic Matter. — The microscopic examination of the total 
residue insoluble in alcohol may furnish valuable information. 

Starch can be detected in this manner ; the microscopic examina- 



198 ANALYSIS IN OIL AND FAT INDUSTRIES 

tion may be confirmed by the iodine test. If a quantitative examination 
is required, the starch is converted to glucose. The residue insoluble in 
alcohol is washed on the filter with cold water to remove substances 
soluble in water, and dextrin, and is then boiled with dilute sulphuric 
acid, the water being replaced as it evaporates. The liquid is neutralised 
with potassium carbonate, filtered, and the glucose determined by 
Fehling's solution. 

Dcxtriri is removed by cold water together with the soluble salts. 
It is determined by precipitation with alcohol. This is best done in a 
small beaker weighed together with a glass rod. The liquid is 
vigorously stirred so that all the dextrin settles out on the sides of the 
beaker. The aqueous solution is then decanted, the residue washed 
with alcohol, and determined by weighing after drying at ioo°. 

Gelatin is removed by washing the residue insoluble in alcohol with 
hot water. The filtrate is then tested with tannic acid to corroborate 
the presence of gelatin. 

(/) Other Substances which occur in Soaps. 

1. Glycerol. — The small quantities of glycerol left behind in hard 
soaps prepared by the boiling process can be determined with accuracy 
only by working with a large quantity of soap. On decomposing the 
soap with mineral acid, the glycerol passes into the aqueous solution ; 
this is examined by the method described below (p. 202) for the 
"determination of glycerol in soap lyes." From the quantity of glycerol 
found a conclusion may be drawn as to whether a hard soap has been 
prepared by the cold process or not. In this case about 5 per cent, of 
glycerol will be found. The absence of glycerol in a soft soap proves 
that the soap has been manufactured from " fatty acids." 

Considerable quantities of glycerol are added to certain toilet soaps 
in the milling process. Glycerol must, in virtue of its cosmetic pro- 
perties, be considered a valuable constituent of such soap. It is determined 
by dissolving the soap in water, separating the fatty matter by means 
of a mineral acid, and filtering. The filtrate is neutralised with barium 
carbonate, evaporated to a syrup, and the residue extracted with a 
mixture of 3 parts of 95 per cent, alcohol and i part of ether. The 
alcoholic solution is filtered, evaporated on the water-bath to a small 
volume, and finally dried in a desiccator. The glycerol in the crude 
glycerin thus obtained is then estimated by the acetin method (p. 123). 

In case a soap also contains sugar, the sugar must first be removed. 

2. Sugar (Saccharose) is found in considerable quantities (up to 25 
per cent, and more) in cheap, transparent soaps. The determination of 
the cane sugar is best effected by boiling the filtrate obtained in (^^), 
or an aliquot portion, with dilute sulphuric acid, to invert the sugar, 
then making the solution alkaline, and heating with Fehling's solution. 



SOAP 199 

after diluting considerably to prevent oxidation of the glycerol. The 
cuprous oxide which separates out is determined in the usual way and 
calculated to cane sugar. If the quantity of sugar is considerable, it 
may be determined polarimetrically. 

If glycerol and sugar are present simultaneously, they are separated 
by the method of E. Donath and J. Mayrhofer,i ^vhich consists in adding 
a sufficient quantity of slaked lime to combine with the sugar, then an 
equal quantity of washed and ignited sand, evaporating to a syrup, 
powdering the residue after cooling, and extracting in a closed flask 
with 80-100 c.c. of a mixture of equal volumes of alcohol and ether. 
The solution will then contain the glycerol free from sugar, and the 
glycerol present is determined as in (i). 

3. Carbolic Acid. — The determination of "carbolic acid" (phenol 
and cresols) in carbolic soaps is carried out with sufficient accuracy by 
the following method (Lewkowitsch) : — 

A considerable quantity of the sample (about 100 g.) is weighed out, 
dissolved in hot water, and sufficient sodium hydroxide solution added 
to make it strongly alkaline. The soap is then salted out with common 
salt, the curdy soap filtered off, and the soap washed with salt solution. 
The solution, which now contains the phenol and cresols as sodium 
salts, is evaporated down, and any dissolved soap is precipitated by a 
further addition of common salt. The solution is filtered again, evapor- 
ated down to a small volume, introduced into a graduated stoppered 
cylinder of 50-100 c.c. capacity, and common salt added until some 
remains undissolved ; the solution is then acidified with sulphuric acid. 
The volume of the separated phenols is read off, and the number 
of cubic centimetres is reckoned as equivalent to the same number 
of grams. 

If greater accuracy be required, the separated phenols are extracted 
with ether, the ether evaporated off, and the phenol and cresols 
determined by the methods described in the Section on " Coal Tar," 
Vol. ii., part ii., pp. Sii e^ seq. 

Metallic Soaps. 

These are either salts of the fatty acids or of rosin acids, or mixtures 
of both, as, for instance, the driers described on p. 163. To this class 
of soaps belong the Lend Plasters, chiefly lead oleate ; Aluminiu7n 
Oleate, which is used to thicken lubricating oil ; Lime Soaps, which 
are used in the manufacture of lubricating greases ; Magnesium Oleate, 
used in petroleum spirit solution by dry-cleaners as a protection against 
the generation of electric sparks ; and, finally, Zific, Lron, Chromium, 
and Copper Soaps, used in anti-fouling and anti-rusting paints. 

For analysis, the metallic soaps are decomposed by a suitable 

1 Z. anal. Chem., i88l, 20, 383- 



200 ANALYSIS IX OIL AND FAT INDUSTRIES 

mineral acid (hydrochloric, nitric, sulphuric), the fatty and rosin acids 
being obtained as an oily layer, or, if the salts are decomposed under 
ether (which is frequently the more suitable method), the acids pass 
into the ether layer and the metal into the acid solution. The separated 
fatty and rosin acids are examined as described above, 

i7/.— GLYCERIN. 

The glycerins met with in commerce are classified as : i. Crude 
glycerin ; 2. Distilled glycerin ; Dynamite glycerin ; 3. Chemically pure 
glycerin. 

I. Crude Glycerin. 

Three kinds of crude glycerin are distinguished in commerce : (a) 
Crude saponification glycerin ; {/>) Crude distillation glycerin ; (c) Soap- 
lye crude glycerin ; Soap crude glycerin. 

(a) Crude Saponification Glycerin. 

This is a product of the autoclave process (see p. 173). It is 
evaporated down to a sp. gr. of 1-240- 1-242, and sold as " 28° Be. saponi- 
fication glycerin" or "crude candle glycerin." It has a pure sweet 
taste, and varies in colour from bright yellow to dark brown. It gives 
only a slight precipitate with lead acetate, and scarcely any turbidity 
with hydrochloric acid. The valuation of this glycerin comprises the 
determination of the ash, which should not exceed 0-3-0-5 per cent., the 
determination of the glycerol, and of the organic impurities. 

The glycerol is best determined by the acetin method as described 
in the Section on "Oils, Fats, and Waxes" (p. 123). Of the oxidation 
methods, only Hehner's modification of the bichromate method can 
be recommended. The author has, however, shown that this method 
gives too high a percentage, especially in the case of impure glycerins.^ 
Since, nevertheless, the bichromate method is still frequently used 
in commercial analysis, it may be described here. The following 
normal solutions are required : (i) A solution of potassium bichromate 
containing 74-86 g. K^Cr^Oy per litre. Hehner recommends the 
addition of 150 c.c. of concentrated sulphuric acid before the solution is 
made up to 1000 c.c. The author considers it preferable to keep the 
unacidified solution as a stock solution, and to add the sulphuric acid 
only at the time of the experiment. The actual oxidising value of the 
solution must be determined by titrating a known solution of ferrous 
sulphate or pure ferrous ammonium sulphate, or pure iron wire. (2) 
Solution of ferrous ammonium sulphate, containing about 240 g. per 
litre. (3) A bichromate solution, prepared by diluting 100 c.c. of 

> Analyst, 1903, 28, 104. 



GLYCERIN 201 

solution (i) to looo c.c. The solution (2) must correspond accurately 
to the strong bichromate solution of which i c.c. is equivalent to o-oi g. 
of glycerol. 

For the determination about 1-5 g. of crude glycerin is accurately 
weighed out into a 100 c.c. flask, diluted with water, silver oxide added 
(or copper sulphate and potassium hydroxide solution), and after 
standing for a short time a few drops of lead acetate are added and the 
whole made up to 100 c.c. After filtering, 25 c.c. of the solution are 
transferred to a beaker, previously cleansed with concentrated sulphuric 
acid and potassium bichromate, and 40 c.c. of the concentrated 
bichromate solution are added. As the bichromate solution is un- 
avoidably a concentrated one, it is necessary not only to measure it 
with great care, but also to observe the temperature of the solution. 
Hehner states that this bichromate solution expands 0-05 per cent, per 
degree. The author avoids corrections by keeping the solutions at 
normal temperature in a large water-bath until the titration is finished. 

Then 25 c.c. of concentrated sulphuric acid are added, the beaker is 
covered with a watch-glass, and placed for two hours in boiling water. 
The excess of bichromate is then reduced with an excess of ferrous 
ammonium sulphate solution, and the excess of the latter finally titrated 
back with the dilute bichromate solution, potassium ferricyanide being 
used as indicator. 

The glycerol content of commercial samples varies, as a rule, between 
85 and 90 per cent. 

Organic Impurities are determined quantitatively by heating a few 
grams gradually to 160° in a platinum dish in a drying oven. Rapid 
heating tends to cause the formation of polyglycerols, which of course 
lead to incorrect results. It is best to moisten the glycerin from time 
to time with a few drops of water, so that the glycerol may evaporate 
with the water. The residue is dried to constant weight. The amount 
thus found is the sum of the ash and organic impurities. The ash is 
found by incineration, and subtracted from the total residue found. 

Crude glycerin obtained by the fermentation process is also some- 
times termed " saponification glycerin " ; it should be noted that it 
contains, as a rule, a considerably larger amount of ash and organic 
impurities.^ 

(6) Crude Distillation Glycerin. 

This crude glycerin is obtained from the acid water resulting from 
the acid saponification process. The solutions are evaporated down to 
a sp. gr. of I -240- 1 -242. The crude glycerin has generally a bright 
yellow colour and a sharp astringent taste ; when rubbed on the hand it 
has an unpleasant odour. As a rule it contains 84-86 per cent, of 

^ CJ. Lewkowitsch, Chemical Technology, etc., vol. iii., p. 332. 



202 ANALYSIS IN OIL AND FAT INDUSTRIES 

glycerol. The ash generally varies from 2-3-5 P^^ cent. The per- 
centage of glycerol can be determined with greater accurac)- by the 
acetin method than by oxidation. This crude gl)'ccrin gives a decided 
precipitate with lead acetate ; on addition of hydrochloric acid a marked 
turbidity is generally obtained (fatty acids). 

A product of a similar character is the gl)'cerin obtained by 
Twitchell's process (p. 173). 

(c) Crude Soap-lye Glycerin ; Crude Soap Glycerin. 

This glycerin is obtained from waste soap-lyes. The specific gravity 
of the commercial product should not be below 1-3, the content of 
glycerol should be at least 80 per cent, and the proportion of salts 
should not exceed 10-5 per cent. 

The percentage of glycerol is best determined by the acetin method 
in preference to the bichromate method (p. 200). 

For the determination of the ash, 3-5 g. are slowly incinerated in a 
platinum dish over a small burner. When the bulk of the glycerol has 
been driven off, the dish is more strongly heated ; a voluminous 
carbonaceous residue remains in the dish. The organic matter is then 
burnt off, care being taken that no sodium chloride volatilises. The 
residue, which contains some carbon, is exhausted with water, and the 
filtrate evaporated in the platinum dish on a water-bath. This residue 
must be white ; it is heated to dryness (not over 400° to avoid volatilisa- 
tion of sodium chloride), and weighed. The carbon residue is burnt, and 
the residual ash is also weighed ; this is especially necessary when the 
sample contains lime. 

Crude glycerin which contains sulphates and thiosulphates is 
almost worthless to the refiner ; the qualitative detection of these sub- 
stances is therefore of importance. 

Recently an International Committee, consisting of manufacturers 
and some analytical chemists, has published, under the title of " Inter- 
national Standards for the Analysis of Crude Glycerin," somewhat 
more detailed methods of examining crude soap-lye glycerins,^ 

2. Distillation Glycerin ; Dynamite Glycerin. {C/. the 
Section on " Explosives," Vol. ii., part i., p. 490.) 

These glycerins are obtained from the above-described crude 
glycerins by distillation. 

The distilled glycerins vary in colour from yellow to almost white. 
Their proportion of glycerol varies according to the specific gravity, 
which generally lies between 1-220 and 1-260; it can be found approxi- 
mately from the specific gravity {cf. Table 35, p. 205). As, however, 

» J. Soc. C/iem. Ind., 191 1, 30, S56 ; 1912, 31, 1084 ; 1913, 32, 1039- 



GLYCERIN 203 

these glycerins contain a little ash, it is necessary in accurate analyses 
to determine the glycerol by the acetin method (or by an oxidation 
method, such as the bichromate or even the permanganate method, 
p. 207). In this case also the oxidation methods easily lead to high 
results. Dynamite glycerin is a special quality of distilled glycerin 
which has a specific gravity of from i-26i-i-263. The colour varies from 
deep yellow to bright pale yellow. From a large number of specifications 
regulating the conditions of sale of this glycerin, the author has 
extracted the following requirements : — 

(a) Specific Gravity. — This must not be less than 1-261 at 15-5°. 

(b) Liine^ Magnesimn, and Aluviina must be absent. 

(c) Chlorides may only be present in traces. i c.c. of glycerin 
diluted with 2 c.c. of water must not give a decided milky turbidity with 
silver nitrate. 

(d) Arsenic. — Only traces are permitted. As the Gutzeit test 
(p. 208) is too sensitive, the following method is used. The sample is 
made just alkaline with a very small quantity of ammonia, and silver 
nitrate is added when no milky turbidity should be observable. An 
excess of ammonia is, to be avoided, as silver arsenite is soluble 
in ammonia. 

(e) Foreign Organic Matter. — i c.c. of the sample is diluted with 2 
c.c. of water, and a {&w drops of a 10 per cent solution of silver nitrate 
are added. On standing for ten minutes there should be no brown or 
black coloration. 

(f) Total Residue. — This is determined as described above (p. 201). 
(Polyglycerols). 

(g) Free Acid. — The glycerin must not redden blue litmus paper. 
Volatile fatty acids are detected most readily by the pleasant odour 
emitted (recalling that of pine apple) on warming the sample 
with alcohol and concentrated sulphuric acid. On diluting i c.c. of the 
sample with 2 c.c. of water, and adding concentrated hydrochloric acid, 
no turbidity should be noticeable. 

(h) Nitration and Separation Test) — A commercial sample may 
pass all the above-mentioned tests satisfactorily and yet be unsuitable 
for the manufacture of nitroglycerin. Its suitability for this purpose 
must, therefore, be especially ascertained by the following method, which 
is based upon the large scale process. A mixture of i part by weight 
of fuming nitric acid of sp. gr. 1-5 with 2 parts by weight of pure 
concentrated sulphuric acid of sp. gr. 1-845 is prepared, and allowed to 
cool in a closed vessel, and 375 g. of this mixture are weighed into 
a beaker of about 500 c.c. capacity ; a thermometer which serves 
as a stirrer during the nitration is introduced, and the beaker is placed 
in a capacious vessel of cold water. The water is kept circulating by 

^ Lewkowitsch, Chem. Zeit., 1895, 19, 1423. 



204 ANALYSIS IN OIL AND FAT INDUSTRIES 

passing it through a stout rubber tube carefully laid on to the sides of 
the cooling vessel. The water is allowed to run away by overflowing 
the vessel. It should be carefully noted that the rubber tube must be 
securely attached to the tap if the nitration is carried on near the water- 
supply tap, as it may easil\- happen that it is thrown off the tap owing 
to a sudden alteration of pressure in the supply pipe. If any water 
is thrown into the nitration mixture, the temperature may easily rise 
to danger point. The safest plan is therefore to use a thin-walled 
beaker, so that in case of emergency the thermometer may be quickly 
pushed through the bottom. 

When the temperature of the acid mixture has fallen to 12^-15^ 
50 g. of the dynamite glycerin to be tested is weighed out into a lipped 
beaker and allowed to fall, drop by drop, into the acid, whilst continually 
stirring with the thermometer. The temperature should be read after 
the addition of each drop. As this operation is not without danger, it 
is best for an unpractised experimenter to have the process demonstrated 
to him. If this be impossible the nitration should be performed very 
slowly and exactly as described, that is, with continual stirring to avoid 
any local overheating, taking care that no further glycerin be added, 
until the temperature has fallen to 25°. A temperature of 30' must 
never be exceeded. A practised operator will, of course, proceed much 
more quickly. 

When all the glycerin has been introduced the stirring is continued 
until the temperature falls to 15°. The mixture of nitroglycerin and 
acids is then transferred to a perfectly dry separating funnel. (It is 
best to rinse out the separator with concentrated sulphuric acid 
beforehand.) 

If the glycerin is of good quality, the nitroglycerin separates 
quickly, floating on the acid as an oily, somewhat turbid layer. The more 
rapidly the separation into two layers with a sharply defined dividing 
line takes place, the better is the glycerin. If slimy or flocculent 
particles remain suspended in the nitroglycerin, or the separation 
is incomplete after five to ten minutes, or if the dividing line is indistinct 
in consequence of a cloudy intermediate layer, the gl)cerin is unsuitable 
for the manufacture of nitroglycerin. 

In the case of a very bad glycerin no separating line at all can be 
observed, and the nitroglycerin appears honeycombed with cellular 
matter which separates out only after many hours' standing. Such a 
glycerin must of course be rejected. 

In consequence of the danger attending this test, it has been 
proposed to reduce the quantity of glycerin taken for the determination 
to 15 g. This should, however, be the lowest permissible limit, as the 
results of the nitration become absolutely unreliable when as little as 
10 g. are taken. 



GLYCERIN 



205 



Table 35. 
Specific Gravities of Aqueous Solutions of Chemically pure Glycerin. 





Lenz. 


Strohmer. 


Gerlach. 


Nicol. 


Glycerol. 










Sp. gr. atl2'tol4°C. 


Sp. gr. at 17°-5C. 


Sp. gr. atl5°C. 


Sp. gr. at 20° C. 


Sp. gr. at 20° C. 


Per cent. 


Water at 12° =1. 


Water at 17° -5 = 1. 


Water at 15°= 1. 


Water at 20° = 1. 


Water at 20°= 1. 


100 


1-2691 


1-262 


1-2653 


1-2620 


1-26348 


99 


1-2664 


1-259 


1-2628 


1 -2594 


1-26091 


98 


1-2637 


1-257 


1-2602 


1-2568 


1-25832 


97 


1-2610 


1-254 


1-2577 


1-2542 


1-25572 


96 


1-2584 


1 -252 


1-2552 


1-2516 


1-25312 


95 


1-2557 


1-249 


1-2526 


1-2490 


1-25052 


94 


1-2531 


1-246 


1-2501 


1-2464 


1-24790 


93 


1-2504 


1-244 


1-2476 


1-2438 


1-24526 


92 


1-2478 


1-241 


1-2451 


1-2412 


1-24259 


91 


1-2451 


1-239 


1 -2425 


1-2386 


1-23990 


90 


1-2425 


1 -236 


1-2400 


1-2360 


1-23720 


89 


1-2398 


1-233 


1-2373 


1 -2333 


1-2.3449 


88 


1-2372 


1-231 


1-2346 


1-2306 


1-23178 


87 


1-2345 


1-228 


1-2319 


1-2279 


1-22907 


86 


1-2318 


1-226 


1 -2292 


1-2252 


1-22636 


85 


1-2292 


1-223 


1-2265 


1 -2225 


1-22365 


84 


1-2265 


1-220 


1-2238 


1-2198 


1-22094 


83 


1-2238 


1-218 


1-2211 


1-2171 


1-21823 


82 


1-2212 


1-215 


1-2184 


1-2144 


1-21552 


81 


1-2185 


1-213 


1-2157 


1-2117 


1-21281 


80 


1-2159 


- 1-210 


1-2130 


1-2090 


1-21010 


79 


1-2122 


1-207 


1-2102 


1-2063 


1 -20739 


78 


1-2106 


1-204 


1 -2074 


1-2036 


1-20468 


77 


1-2079 


1-202 


1-2046 


1-2009 


1-20197 


76 


1-2042 


1-199 


1-2018 


1-1982 


1-19925 


75 


1-2016 


1-196 


1-1990 


1-1955 


1-19653 


74 


1-1999 


1-193 


1-1962 


1-1928 


1-19.381 


73 


1-1973 


1-190 


1-1934 


1-1901 


1-19109 


72 


1-1945 


1-188 


1-1906 


1-1874 


1-18837 


71 


1-1918 


1-185 


1-1878 


1-1847 


1-18565 


70 


1-1889 


1-182 


1-1850 


1-1820 


1-18293 


69 


1-1858 


1-179 






1-18020 


68 


1-1826 


1-176 






1-17747 


67 


1-1795 


1-173 


... 




1-17474 


66 


1-1764 


1-170 


... 




1-17201 


65 


1-1733 


1-167 


1-1711 


1-1685 


1-16928 


64 


1-1702 


1-163 


• ■ • 




1-16654 


63 


1-1671 


1-160 






1-16380 


62 


1-1640 


1-157 


... 




1-16107 


61 


1-1610 


1-154 






1-15834 


60 


1-1582 


1-151 


1-1570 


1 -1550 


1-15561 


59 


1-1556 


1-149 


... 




1-15288 


58 


1-1530 


1-146 


... 




1-15015 


57 


1-1505 


1-144 


... 




1-14742 


56 


1-1480 


1-142 


... 




1-14469 


55 


1-1455 


1-140 


1-1430 


1-1415 


1-14196 


54 


1-1430 


1-137 






1-13923 


53 


1-1403 


1-135 


... 


• • ■ 


1-13650 


52 


1-1375 


1-133 


... 




1-13377 


51 


1-1348 


1-130 


... 




1-13104 


50 


1-1320 


1-128 


1-1290 


1-1280 


1-12831 


45 


1-1183 




1-1155 


1-1145 


1-11469 


40 


1-1045 


• • • 


1-1020 


1-1010 


1-10118 


35 


1-0907 




1-0885 


1 -0875 


1-08786 


30 


1-0771 


• ■ • 


1-0750 


1-0740 


1-07469 


25 


1 -0635 


• • • 


1-0620 


1-0610 


1-06166 


20 


1-0498 




1-0490 


1-0480 


1-04884 


15 


1-0374 








1-03622 


10 


1-0245 


■ * • 


1-0245 


1-6235 


1-02391 


5 


1-0123 


• • « 


... 




1-01184 





1-0000 


... 


1-0000 


1-6000 


1-00000 



206 



ANALYSIS IN^ OIL AND FAT INDUSTRIES 



3. Chemically pure Glycerin. 

This glycerin forms the purest commercial product, and should — 

except for the presence of a small proportion of water — represent the 

chemical compound, CgH^Oa, i.e. glycerol. In commerce the following 

qualities are recognised : — 

Chemicallypureglycerinofsp.gr. . . . i'24 

1-25 



» 



» 

5> 



1-26 



The percentage is most rapidly determined from the specific gravity 
in accordance with Table 35, p. 205. 

When determining the specific gravity of the most concentrated 
glycerin, it is of importance to ensure that it is free from air-bubbles. To 
avoid these it is best to warm the sample in a corked flask until all the 
bubbles have risen to the top. The flask is then allowed to cool to the 
ordinary temperature, and the glycerin carefully transferred to a pyk- 
nometer by pouring it down the side of the vessel. 

Table 36. 
The Specific Gravities and Refractive Indices of Aqueous 
Solutions of Glycerin. (Lenz.) 



"2 

>. 

"3) 

00 



>> 

Ji 

< 


(-1 



*^ 


Is 

if 

p— I 


i 

s 

>> 

"3) 

3 
S 
>» 

•5 



CI 

d 

32 


5 ^ 

efi 


Anhydrous glycerol. 


e 

-»^ 



d 

OQ 


X . 

CO 

•a „• 
.5 "^ 


1 

>> 

a 

•a 
>> 

.a 

< 


l-H 

•Ad 

CI 

•s 


X . 

a 00 

.^ r-t 


100 


1-2691 


1-4758 


74 


1-1999 


1-4380 


49 


1-1293 


1-3993 


24 


1-0608 , 1-3639 


99 


1-2664 


1-4744 


73 


1-1973 


1-4366 


48 


1-1265 


1-3979 


23 


1-0580 


1-3626 


98 


1-2637 


1-4729 


72 


1-1945 


1-4352 


47 


1-1238 


1-3964 


22 


1-0553 


1-3612 


97 


1-2610 


1-4715 


71 


1-1918 


1-4337 


46 


1-1210 


1-3950 


21 


1-0525 


1-3599 


96 


1-2584 


1-4700 


70 


1-1889 


1 -4321 


45 


1-1183 


1-3935 


20 


1-0498 


1-3585 


95 


1-2557 


1-4686 


69 


1-1858 


1-4304 


44 


1-1155 


1-3921 


19 


1-0471 


1-3572 


94 


1-2531 


1-4671 


68 


1-1826 


1-4286 


43 


1-1127 


1-3906 


18 


1-0446 


1-3559 


93 


1-2504 


1-4657 


67 


1-1795 


1-4267 


42 


1-1100 


1-3890 


17 


1-0422 


1-3546 


92 


1-2478 


1-4642 


66 


1-1764 


1-4249 


41 


1-1072 


1 -3875 


16 


1-0398 


1-3533 


91 


1-2451 


1-4628 


65 


1-1733 


1-4231 


40 


1-1045 


1-3860 


15 


1-0374 


1-3520 


90 


1-2425 


1-4613 


64 


1-1702 


1-4213 


39 


1-1017 


1-3844 


14 


1-0349 


1-3507 


89 


1-2393 


1-4598 


63 


1-1671 


1-4195 


38 


1-0989 


1 -3829 


13 


1-0332 


1-349 J 


88 


1 -2372 


1-4584 


62 


1-1640 


1-4176 


37 


1 -0962 


1-3813 


12 


1-0297 


1-3480 


87 


1-2345 


1-4569 


61 


1-1610 


1-4158 


36 


1-0934 


1-3789 


11 


1-0271 


1-3467 


86 


1-2318 


1 -4555 


60 


1-1582 


1-4140 


35 


1-0907 


1-3785 


10 


1-0245 


1-3454 


85 


1-2292 


1-4540 


59 


1-1556 


1-4126 


34 


1 -0880 


1-3772 


9 


1-0221 


1-3442 


84 


1 -2265 


1-4525 


58 


1-1530 


1-4114 


33 


1-0852 


1-3758 


8 


1-0196 


1-3430 


83 


1-2238 


1-4511 


57 


1-1505 


r4]02 


32 


1-0825 


1-3745 


7 


1-0172 


1-3417 


82 


1-2212 


1-4496 


56 


1-1480 


1-4091 


31 


1-0798 


1 -3732 


6 


1-0147 


1-3405 


81 


1-2185 


1-4482 


55 


1-1455 


1-4079 


30 


1-0771 


1-3719 


5 


1-0123 


1 -3392 


80 


1-2159 


1-4467 


54 


1-1430 


1-4065 


29 


1-0744 


1-3706 


4 


1-0098 


1-3380 


79 


1-2122 


1-4453 


53 


1-1403 


1-4051 


28 


1-0716 


1-3692 


3 


1-0074 


1-3367 


78 


1-2106 


1-4438 


52 


1-1375 


1-4036 


27 


1-068!) 


1-3679 


2 


1-0049 


1 -3355 


77 


1-2079 


1-4424 


51 


1-1348 


1 -4022 


26 


1-0663 


1-36C6 


1 


1 -0025 


1-3342 


76 


1-2046 


1-4409 


50 


1-1320 


1-4007 


25 


1-0635 


1-3652 





1-0000 


1-3330 


75 


1-2016 


1-4395 














1 

i 







GLYCERIN 



207 



The refractive index may also be used to determine the proportion 
of glycerin. Table 36, p. 206, gives the numbers determined by Lenz. 

For exact determinations it is necessary to adhere to the tempera- 
tures given, and for this reason Lenz recommends determining the 
refraction of the glycerin, and then that of pure water, at the same 
temperature, immediately afterwards; the influence of temperature and 
of small fluctuations in the adjustment of the scale are thus eliminated. 

The differences between the refractive indices of glycerin solutions 
and of pure water are given in the following Table : — 



Table 37. 

Differences between the Refractive Indices of Aqueous Solutions 
of Glycerin and Pure Water. (Lenz.) 



si 

■5) 


Per cent, of 

glycerol 
by weight. 


p a> 


Per cent, of 

glycerol 

by weight. 


si 

"So a 


Per cent, of 

glycerol 
by weight. 


"21 

■3) a 


Per cent, of 

glycerol 
by weight. 


0-1424 


100 


0-1046 


74 


0-0645 


48 


0-0288 


22 


0-1410 


99 


0-1032 


73 


0-0630 


47 


0-0275 


21 


0-1395 


98 


0-1018 


72 


0-0616 


46 


0-0261 


20 


0-1381 


97 


0-1003 


71 


0-0601 


45 


0-0238 


19 


0-1366 


96 


0-0987 


70 


0-0587 


44 


0-0225 


18 


0-1352 


95 


0-0970 


69 


0-0572 


43 


0-0212 


17 


0-1337 


94 


0-0952 


68 


0-0556 


42 


0-0199 


16 


0-1323 


93 


0-0933 


67 


0-0541 


41 


0-0186 


15 


0-1308 


92 


0-0915 


66 


0-0526 


40 


0-0173 


14 


0-1294 


91 


0-0897 


65 


0-0510 


39 


0-0160 


13 


0-1279 


90 


0-0889 


64 


0-0495 


38 


0-0146 


12 


0-1264 


89 


0-0861 


63 


0-0479 


37 


0-0133 


11 


0-1250 


88 


0-0842 


62 


0-0464 


36 


0-0120 


10 


0-1235 


87 


0-0824 


61 


0-0451 


35 


0-0108 


9 


0-1221 


86 


0-0806 


60 


0-0438 


34 


0-0096 


8 


0-1206 


85 


0-0792 


59 


0-0424 


33 


0-0083 


7 


0-1191 


84 


0-0780 


58 


0-0411 


32 


0-0071 


6 


0-1177 


83 


0-0768 


57 


0-0398 


31 


0-0058 


5 


0-1162 


82 


0-0757 


56 


0-0358 


30 


0-0046 


4 


0-1148 


81 


0-0745 


55 


0-0372 


29 


0-0033 


3 


0-1133 


80 


0-0731 


54 


0-0385 


28 


0-0021 


2 


01119 


79 


00717 


53 


0-0345 


27 


0-0008 


1 


01104 


78 


0-0702 


52 


0-0332 


26 


0-0000 





0-1090 


77 


0-0688 


51 


0-0318 


25 






0-1075 


76 


0-0663 


50 


0-0315 


24 






0-1061 


75 


0-0659 


49 


0-0302 


23 







For the determination of the refractive index of dilute glycerin 
solutions, the " immersion-refractometer " may also be used. It should 
be noted, however, that this instrument may only be used for solutions 
containing less than 28 g. of glycerol in 100 c.c. of solution. 

In the case of dilute solutions containing chemically pure glycerin, 
the best method of estimation is oxidation with either bichromate or 
permanganate. The latter is best carried out by using the modification 



208 ANALYSIS IN OIL AND FAT INDUSTRIES 

of Waiiklyn and Fox's process proposed by R. Benedikt and R. 
Zsigmondy.^ This depends upon the complete oxidation of the 
glycerol in cold, strongly alkaline solution to oxalic acid, according to 
the equation : — 

C3HP3+3O, = C,H..0, + C0, + 3H,0. 

For the test, 0-2-0-3 g. of highly concentrated glycerin or the corre- 
sponding quantity of dilute glycerin (calculated approximately from the 
specific gravity) are placed in a capacious flask and diluted to about 
250 c.c. with water. 10 g. of solid potassium hydroxide are added, and 
then a 5 per cent, solution of potassium permanganate, at the ordinary 
temperature, until the solution is no longer green but blue or blackish. 
If preferred, solid, finely powdered potassium permanganate may be 
added. On heating to boiling, hydrated manganese dioxide separates 
out, and the liquid becomes red. A solution of sulphurous acid or 
sodium sulphite is then added until the liquid is just decolorised. The 
solution is filtered through a smooth filter paper of such a size that it 
takes at least half of the liquid at once, the filter is carefully washed 
with hot water, and the filtrate acidified with acetic acid. The last 
washings are frequently turbid through containing some hydrated 
manganese dioxide ; this turbidity disappears, however, in the acidifica- 
tion with acetic acid as the liberated sulphurous acid reduces the 
manganese dioxide. The solution is heated to boiling, and the oxalic 
acid precipitated by the addition of 10 c.c. of a 10 per cent, solution 
of calcium chloride. The precipitate of calcium oxalate is further 
treated in the usual way, and the oxalic acid is calculated to glycerol 
according to the above equation. 

The content of ash plus polyglycerols should not exceed 0-03 per 
cent. ; the ash itself should not exceed o-oi per cent. 

Acrolein (and other reducing substances) are best detected by the 
addition of a few drops of silver nitrate solution to the dilute solution 
of the gl}xerin, the solution being allowed to stand for twent}'-four 
hours at the ordinary temperature. The test is still more delicate if 
ammoniacal silver nitrate be used. 

Volatile Fatty Acids are recognised by heating the gl\cerin with 
alcohol and concentrated sulphuric acid, when ethyl esters of the acids 
are formed, which can be detected by their odour, recalling that of pine 
apple. 

Sugar is determined polarimetrically. 

Arsenic should be entirely absent. A rapid and most sensitive test 
for arsenic is that of Gutzeit. For this test, 2 c.c. of the sample are 
introduced into a tall test tube and treated with zinc (free from arsenic) 
and a few cubic centimetres of absolutely pure dilute sulphuric acid. 

1 Chem. Zeit., 1885, 9, 975 ; /. Soc. Clum. bid., 1885, 4, 610. 



GLYCERIN 209 

The mouth of the test tube is covered with a close-fitting cap of filter 
paper, two or three layers in thickness, the innermost layer of which has 
been moistened with a 50 per cent, solution of silver nitrate with the aid 
of a glass rod. In presence of arsenic, arseniuretted hydrogen is evolved. 
After standing for ten minutes, the paper cap is taken off. There 
should be no deep yellow stain on the inner layer of paper. Only a 
very pale yellow coloration is permissible. This test is so extremely 
sensitive, that it is absolutely essential to carry out a blank test with the 
same reagents. This silver nitrate test is almost too sensitive (although 
commercial glycerins are met with which give no colour after ten 
minutes), and has been replaced by the less delicate test, in which 
the silver nitrate solution is replaced by a concentrated solution of 
mercuric chloride. A glycerin may be considered as practically free 
from arsenic when no yellow colour is obtained after ten minutes. 
If mercuric chloride is used, hydrochloride acid may be taken 
instead of sulphuric ; with silver nitrate, hydrochloric acid is not 
permissible, as small quantities of hydrogen chloride gas may be 
evolved if the solution becomes warm. 

The Marsh-Berzelius test may of course also be used. This is fully 
described in the section on the " Manufacture of Sulphuric Acid," Vol. i,, 
part i., pp. 363 et seq. 



Literature. 

Lewkowitsch, J. — Chemical Technology and Analysis of Oils, Fats, and Waxes, 

Vol. I., 5th edition, 1913 ; Vols, II. and III., 4th edition, 1909, 
Lewkowitsch, J. — The Laboratory Companion to Fats and Oils industries, 1901. 



Ill O 



RESINS, BALSAMS, AND GUM-RESINS 

By K. DiETERlCH, Ph.D., Lecturer in Pharmaceutical Chemistry, the Royal \'eterinary 
High School, Dresden. English translation revised by the late J. LewkowitsCH, 
M.A., Ph.D. 

Resins, balsams, and gum-resins are the secretions of chiefly exotic 
plants, and represent mixtures of varying composition. They are used 
in industry and in medicine. The methods employed to obtain them 
are usually so cumbersome and so crude that the substances which come 
on the market as resin, balsam, and gum-resin are completely changed 
products, differing widely from their original form as they occur in 
nature. Since most of the consignors are non-Europeans, it has been 
possible only in the case of a few resins to obtain authentic samples. 

On account of the great distances from which the resins come, the 
many hands through which they pass, and their completely changed 
and varying composition, the examination of samples obtained direct 
from the tree, and of authenticated purity, is extremely useful and 
of fundamental importance. The analytical data obtained from such 
genuine samples, e.g. of Peru balsam, have led to definite conclusions," 
but have also shown that the commercial article very seldom 
corresponds to the genuine resin. A demand for the genuine article 
would lead to the rejection of nearly all commercial samples. Hence 
in the examination of commercial samples certain variations must be 
allowed, and concordant results, such as are obtained in the case of fats 
and oils, must not be expected ; unfortunately, the analyses of resins 
so far published not only vary within wide limits, but are, speaking 
generally, actually contradictor}-. For this reason it is not possible, at 
present at any rate, to lay down reliable methods of examination, or 
even to fix certain limits within which characteristic values may vary.^ 

As regards classification, the subdivision into resins, balsams, and 
gum-resins has been retained, although numerous attempts have been 
made to classify these substances on a chemical basis.^ This sub- 
division appears to be the most convenient, especially from the stand- 
point of commercial and technical considerations. 

The examination of resins comprises both qualitative and quanti- 

^ C/. K. Dieterich, Analyse der Harze, Ba!same, und Gummiharze nebst ihrer Chemie und 
Pharni.ikognosie, 1 900. 

- Cf. A. Tschirsch, Harze und HarzbehSller. 

210 



METHODS OF ANALYSIS 211 

tative tests. Whereas formerly qualitative tests, colour reactions, etc., 
were used almost exclusively for identification and for evaluation, a 
large number of quantitative tests (to some extent included in the 
Pharmacopoeias) are now available. The most important of these are 
the determination of the acid and saponification values (and their 
difference, the ester values), a method of valuation borrowed from the 
analysis of fats and oils. While the determination of these values 
furnishes really useful numbers, the iodine-bromine values of the resins 
are of minor importance. As more recent proposals the following 
quantitative methods, which may be used to complement the above 
values, may be mentioned : — The methyl value (Gregor and Bam- 
berger), the carbonyl value (Kitt), the acetyl value (K. Dieterich), and 
the examination of the resin alcohols and acids (K. Dieterich). 

The determinations now generally included in the analysis of resins 
are : — 

{a) The Acid Value. 

{b) The Saponification or Resin Value. 

{c) The Ester Value (the difference between (a) and {b). 

(d) Loss at ioo° (Mojsture). 

{e) Ash. 

{/) Proportion soluble in Alcohol. 

{g) Proportion insoluble in Alcohol, 

(//) Specific Gravity. 

And the following more special determinations : — 

{{) Determination of the Cinnamein and Resin Esters in Peru 
Balsam. 

{k) Acetyl, Carbonyl, and Methyl Values. 

(/) Examination of Resin Acids and Alcohols, 

(w) Qualitative Reactions. 

Any single estimation in the case of resins cannot obviously be 
regarded as conclusive, but the relations of the several data obtained 
under the above headings often renders it possible to draw certain 
conclusions, 

A. — Methods of Analysis. 

The meaning of certain terms, as used in this Section, is as 
follows : — 

The Acid Value. — The number of milligrams of potassium 
hydroxide required for the neutralisation of the free acid in i g. of 
the resin. 

The Acid Value of the Volatile Portions. — The number of mil- 
ligrams of potassium hydroxide required to neutralise 500 g. of 
distillate obtained from o-S g. of gum-resin by distillation in a current 
of steam, e.g., in ammoniacum, galbanum. 



212 RESINS, BALSAMS, AND GUM-RESINS 

The Saponification Value. — The number of milligrams of potassium 
hydroxide required to saponify i g. of resin. 

Tiie Resin Value. — The number of milligrams of potassium 
hydroxide required to neutralise i g. of (certain) resins and gum- 
resins on cold fractional saponification with alcoholic potassium 
hydroxide alone. 

The Total Saponification Value (Fractional Saponification). — The 
total number of milligrams of potassium hydroxide required to 
neutralise i g. of (certain) resins and gum-resins on cold fractional 
saponification successively with alcoholic and aqueous potassium 
hydroxide. 

The Gum Value. — The difference between the total saponification 
value and the resin value. 

The Ester Value. — The difference between the acid value and the 
saponification value. 

The Acetyl Value. — The difference between the acetyl saponification 
value and the acetyl acid value. 

The Carbonyl Value. — The percentage of carbonyl oxygen in the 
resin. 

The Methyl Value. — The percentage of methoxyl, calculated as 
" methyl" (CH3), obtained from i g. of the resin. 

The details for the determination of these characteristic values 
depend on the nature of the substance under examination (see 
examples) ; for most resins several alternative methods have hitherto 
been in use. 

(a) The Acid Value. 

I. By Direct Titration (A. Kremel). — If the resin is completely 
soluble in alcohol, chloroform, or benzene-alcohol, the solution of i g. 
of the sample is titrated with Njz or A710 alcoholic potassium 
hydroxide, phenolphthalein being used as the indicator. If the 
substance is not completely soluble an alcoholic extract is titrated 
as above, and the result calculated to i g. of the sample. {Examples : — 
Gum-resins, benzoin, storax.) An alternative method is to prepare 
a water-alcohol extract by heating i g, of the finely ground substance 
with 30 c.c. of water under a reflux condenser, adding 50 c.c. of 96 per 
cent, alcohol, and boiling again under the reflux condenser for fifteen 
minutes for each extraction ; the extract is allowed to cool and is then 
titrated without filtering the solution. {Examples: — Myrrh, bdellium, 
opoponax, sagapenum.) 

2. By Indirect Titration (K. Dieterich). 

(a) In the case of completely or almost completely soluble ester- 
free resins, the alkali simultaneously neutralises the ac'd and dissolves 
the resin, i g. of the ester-free resin is digested in a glass-stoppered 



THE ACID VALUE 213 

bottle with 25 c.c. of A'/2 alcoholic potassium hydroxide solution and 
50 c.c. of light petroleum spirit — or benzene in the case of copal — for 
twenty-four hours ; Nji sulphuric acid, with phenolphthalein as the 
indicator, is used for the titration of the excess of alkali. {Examples : — 
Colophony, dammar, sandarac, mastic, guaiacum, copal.) 

(/3) In the case of partially soluble resins, containing esters which 
are saponified with difficulty, when the alkali neutralises the acid and 
dissolves out the acidic portions, i g. of the finely ground resin is 
digested in a stoppered bottle for twenty-four hours with 10 c.c. of 
alcoholic, and 10 c.c. of aqueous, iV/2 potassium hydroxide solution, 
and the excess of alkali titrated back after addition of 500 c.c. of water. 
{Examples : — Asafoetida, olibanum.) 

(y) In the case of partially soluble resins, containing esters, a 
water-alcohol extract is used, i g. of the finely ground resin is boiled 
with 50 c.c. of water for fifteen minutes under a reflux condenser; 
100 c.c. of strong alcohol are added, the liquid boiled for a further 
fifteen minutes, allowed to cool, and made up to 150 c.c. To 75 c.c. 
of the filtrate, equivalent to 0-5 g. substance, are added 10 c.c. of 
jV/2 alcoholic potassium hydroxide solution, and after standing in a 
small flask for exactly five minutes the solution is titrated back with 
N/2 sulphuric acid, using phenolphthalein as indicator. (Examples : — 
Ammoniacum, galbanum.) 

((5) In the case of almost completely soluble resins, containing easily 
saponifiable esters, the natural product as such is used. The finely 
ground sample is digested for exactly five minutes with 10 c.c. of 
N/2 alcoholic potassium hydroxide solution. {Example : — Benzoin.) 

3. By estimating the Acid Value of the Volatile Acids. — (For 
gum-resins containing much essential oil.) A small quantity of water 
is added to 0-5 g. of the resin in a flask attached to an inclined 
condenser and heated on a sand-bath (to avoid excessive condensation), 
and a current of steam passed through. The condenser tube dips 
into 40 c.c. of N/2 potassium hydroxide solution contained in a 
receiver. When exactly 500 c.c. have passed over, the condenser tube 
is rinsed with distilled water, and the solution titrated back with 
standard acid, using phenolphthalein as the indicator. {Examples: — 
Ammoniacum, galbanum.) 

(6) The Saponification Value. 

I. Determination in the Hot Solution. 

(a) I g. of a completely soluble resin is boiled for thirty minutes 
under a reflux condenser with 25-30 c.c. of N/2 alcoholic potassium 
hydroxide, diluted with alcohol and titrated with N/2 sulphuric acid, 
using phenolphthalein as the indicator. {Examples : — Almost all balsams 
and resins.) 



214 RESINS, BALSAMS, AND GUM-RESINS 

If the substance is not completely soluble, either of the two following 
methods may be used : — 

(,8) The alcoholic extract is titrated exactly as in (a), and the result 
calculated on i g. of the sample. {Examples: — Gum-resins, benzoin, 
storax.) 

(y) Water is added to the sample to dissolve the gummy portions, 
and it is then heated as in (a). {Exa))iple : — Myrrh.) 

2. Determination in the Cold Solution (K. Dieterich). 

(a) In the case of completely soluble resins i g. of the sample is allowed 
to stand for twenty-four hours at the ordinary temperature in a 500 c,c. 
stoppered bottle with 50 c.c. of petroleum spirit of sp. gr. 0-700 at 15", 
and 50 c.c. of iV/2 alcoholic potassium hydroxide solution; it is then 
titrated back with A72 sulphuric acid. To dissolve any salt which may 
have separated on the bottom of the bottle, which may happen with 
Peru balsam, 300 c.c. of water are added before titration. {Exaviples : — 
Peru balsam, copaiba balsam, benzoin, storax.) 

(/3) In the case of incompletely soluble resins, two portions of i g. 
each are powdered and allowed to stand, with frequent shaking, for 
twenty-four hours at the ordinary temperature in a i litre stoppered 
bottle with 50 c.c. of petroleum spirit of sp. gr. 0-700 at 15° and 25 c.c. 
q{ N\2 alcoholic potassium h}'droxide solution, added in the order given. 
One portion is titrated back after addition of 500 c.c. of water with 
N\2 sulphuric acid, using phenolphthalein as the indicator, the liquid 
being agitated during the titration by imparting a rotary motion to 
the flask. This gives the " resin value." To the second portion are 
added 25 c.c. of NI2 aqueous potassium hydroxide and 75 c.c. of 
water; this is allowed to stand, with frequent shaking, for a further 
twenty - four hours, when 500 c.c. of water are added, and is then 
titrated with iV/2 sulphuric acid, with agitation as before. The result 
obtained is the " total saponification value." The difference is termed 
the "gum value." {Examples : — Ammoniacum, galbanum.) 

(c) The Ester Value. 
This value is the difference between the acid and the saponification 
values. 

{d) Loss at 100° (Moisture). 
For this determination from 2-3 g. of the resin are heated in an oven 
at 100" to constant weight. Resins containing essential oils lose, of 
course, volatile substances as well as water. {Examples : — All resins 
except balsams.) 

(e) Ash. 
This is determined by incinerating the residue obtained in {d). 



SOLUBILITY. ESTERS 215 

(/) The proportion Soluble in Alcohol. 
The sample is extracted with 90 or 96 per cent, alcohol, either by 
mixing 10 g. of the sample with sand and extracting in a Soxhlet 
apparatus, or by dissolving in a flask attached to a reflux condenser, 
filtering the resulting solution on a tared paper and washing the 
residue with hot alcohol. The solvent in the filtrate is evaporated 
off and the residue dried at 100' to constant weight. To avoid 
creeping during the evaporation, the dish is placed in water in a larger 
dish, which serves as a water-bath; by adopting this expedient the 
alcohol never rises above the level of the water outside. In the case 
of resins containing essential oils, such as gum-resins, it is preferable 
to estimate the insoluble portion and to calculate from this the 
soluble portion : the volatile portions, which otherwise might be over- 
looked, are thus included in the result. 

(g) The proportion Insoluble in Alcohol. 

The residue from (/) is dried at 100° to constant weight. 

Instead of using alcohol for the extraction in (/"), and (g-), ether, 
petroleum naphtha, light petroleum spirit, chloroform, etc., may be 
employed. 

(h) Specific Gravity at 15°. 

The specific gravity of liquid resins, such as Mecca, Copaiba, and Peru 
balsams, is determined with the Mohr-Westphal balance, and that of 
solid resins by the methods used for wax (see p. 107). 

For solid resins, such as colophony, salt solutions of known concentra- 
tion may be used. 

(/■) Determination of the Cinnamein and Resin Esters 

in Peru Balsam. 

The estimation of the cinnamein is best carried out immediately 
after the determination of the portion soluble in ether (see g above). 
The ethereal filtrate is shaken out twice successively in a separating 
funnel with 2 per cent, sodium hydroxide solution, using 20 c.c. each 
time, washed twice with water and dried for thirty minutes on the 
water-bath (Thoms). 

The determination of the resin esters follows conveniently on the 
cinnamein determination, the brown alkaline resin solution from which, 
after separation from the ethereal liquid, is precipitated with dilute hydro- 
chloric acid. The precipitate is collected on a tared filter and washed 
on the pump until free from chlorine. The resin is dried at 80° to 
constant weight and its percentage calculated. {^Example: — Peru 
balsam.) 



216 RESINS, BALSAMS, AND GUM-RESINS 

(k) The Acetyl, Carbonyl, and Methyl Values. 

1. The Acetyl Value. 

The resin is boiled under a reflux condenser with an excess of acetic 
anhydride and anhydrous sodium acetate either until solution is com- 
plete, or until no more dissolves. The solution thus obtained is poured 
into water, and the separated product collected on a filter and exhausted 
with boiling water until all free acetic acid has been removed. (The in- 
soluble residues from dammar and copal are similarly treated.) The 
acetyl products are dissolved in alcohol and the acid and saponifica- 
tion values determined as described in the section on " Oils, Fats, and 
Waxes," pp. 122 and 1 14. The difference between the acetyl acid value 
and the acetyl saponification value is the "acetyl (ester) value." 
[Examples : — Turpentine, colophony, sandarac, dammar, copal.) 

2. The Carbonyl Value (M. Kitt). 

The substance is warmed with sodium acetate and an accuratel)- 
measured quantity of phenylhydrazine hydrochloride in dilute alcoholic 
solution. The excess of phenylhydrazine hydrochloride is ascertained 
by oxidation with Fehling's solution and measuring the nitrogen 
evolved. The carbonyl value is found from the formula; — 

Percentage of carbonyl oxygen = V — Vq ^-^ where \' is the 

volume of nitrogen obtained from the total phenylhydrazine hydro- 
chloride added, and V^, that of the excess left, both reduced to o'' and 
760 mm., and S the weight of substance used. {Exaviplcs : — Sandarac, 
elemi, colophony, copal, acaroid.) 

3. The Methyl Value (G. Gregor). 

This determination is based upon Zeisel's method. The methoxj'l 
groups present are removed as meth\l iodide by means of h)-driodic 
acid, and the meth}-l iodide estimated as silver iodide.^ 

(/) Examination of the Resin Acids. 
The saponification products of the resins, as obtained above {b i and 
b 2) are decomposed with acid, washed and dried. The resulting 
substances are examined both qualitatively and quantitatively by 
determining their solubility in various solvents, and their acid and 
saponification (also ester) values. {Examples: — Balsams, benzoin, 
colophony, dammar, copal). 

(m) Qualitative Reactions. 
These are described below under the heading B. 

■ C/. G. Gregor, MonalsL, 1 898, 19, 116;/. Soc. Cliem. Ind., 1 898, 17, 609. 



CHARACTERISTIC VALUES 



217 



B. — Characteristic Values and Standards of Quality. 

The subjoined tabular statement of the characteristic values of resins, 
balsams, and gum-resins is based on the determinations of Williams, 
Kremel, von Schmidt and Erban, Gehe and Co., Beckurts and Briiche, 
E. Dieterich, K. Dieterich, Tschirch, and others. The values, which are 
given in round numbers, do not constitute a criterion of purity and 
quality ; they are merely intended to show the limits of the numbers, as 
determined by the several methods of examination employed. The 
solubilities given represent the demands which present experience 
justifies. Only the most important balsams, resins, and gum-resins are 
included in the Tables. 

I. Balsams. 
Copaiba. 



1. Maracaibo. 

Acid value (by a\)* 
Saponification value (by i^la) 
( M '''2a) 
Ester value 

Sp. gr 

Methyl value (by kZ') 



2. Para (Maranham). 

Acid value (by aV) . 
Saponification value (by /'la) 

( M '^2a) 
Ester value 
Sp. gr 



3. Bast Indian (Gur- 
jun Balsam). 

Acid value (by «1) . 
Saponification value (by lAa) 
„ ( „ bla) 
Ester value 
Sp.gr 



4. Peru Balsam. 

Acid value (by al). 
Saponification value (by i^la) 
( ., ^2a) 



Ester value . . . . 
Methyl value (by kZ) 
Cinnamein (by i) . 
Resin esters (by i) . 
Saponification value of cinna- 
mein (by ^la) 
Sp. gr 



75 to 100 



80 

80 

- 0-5 

0-96 



100 
90 
8 
0-99 



25 to fi5 

30 „ 70 

30 „ 60 

2 „ 18 

0-91 „ 0-99 



5 to 20 

8 „ 20 

10 „ 25 

1 „ 15 

0-955 „ 0-980 



40 to 80 
220 „ 260 
240 „ 270 



140 „ 200 
14-4 „ 22-6 
60 „ 61% 
19 „ 28 

240 
1-138 to 1-148 



Solubility. 



Ether . 
Chloroform . 
Petroleum spirit . 
Oil of turpentine . 
Carbon bisulphide 

Alcohol (90%) . 
Ethyl acetate 



Ether . 
Chloroform . 
Benzene 

Oil of turpentine . 
Alcohol (90%) . 
Ethyl acetate 
Petroleum spirit . 
Carbon bisulphide 



Alcohol (90%) . 
Chloroform . 
Ethyl acetate 
Benzene 

Oil of turpentine . 
Ether . 

Petroleum spirit . 
Carbon bisulphide 

Chloroform . 
Ethyl acetate 

Alcohol 



Ether . 
Benzene 
Petroleum spirit 
Oil of turpentine 
Carbon bisul 
phide 



90% 

92 to 98% 

94 

66 

85 



98% 



} 86 „ 88% 



Completely 
soluble 



Only 
partially 
soluble 



1 



Completely 
soluble 



Only 

partially 

soluble 



Completely 
soluble 



] Only 
r partially 
J soluble 

^ Completely 
j soluble 
r Almost 
-! completely 
[ soluble 
Soluble 



The letters and figures refer to the methods given under A (pp. 211 zt seq.). 



218 



RESINS, BALSAMS, AND GUM-RESINS 



II. Resins. 
Amber. 





tiolubility. 








Fused. 


Natural. 


Acid value (by (j1) 


15 to 35 


Alcohol . 


. almost insol. 


.•Mmost insol. 


Saponification value 




Ether . 


. partially sol. 


11 


(by/.l;3) . . 


86 „ 145 


Methyl alcohol 


. almost insol. 




Ester value . 


71 „ 91 


Amyl alcohol . 


. partially sol. 


u 


Moisture 

Ash .... 


1% 
0-2 to 0-3% 


Benzene 


/almost com- 
\ pletely sol. 


r 






Petroleum spirit 


. almost insol. 


)i 






Acetone . 


* 1* 


Insol. 






Glacial acetic acid . 


. partially sol. 


11 






Chloroform . 


M 


11 






Carbon bisulphide . 


falmost com- 
\, pletely sol. 


l Partially sol. 






Oil of turpentine . 


f almost com- 
\ pletely sol. 


I 



Copal, which may be confounded with amber, is soluble in cajuput 
oil, while amber is not. On ignition, amber blackens moist lead acetate 
paper ; copal does not. Adulterants and artificial products from 
colophony arc recognised by their solubility in alcohol and their high 
acid values. 

Benzoin. 



1. Siam. 




2. Sumatra. 




Acid value (by al) . 


120 to 170 


Acid value (by a\) 


95 to 190 


( „ «2o) . 


140 „ 170 


II II ( 11 ''25) . 


100 „ 130 


Saponification value (by 61^) 


170 „ 210 


Saponification value (by /'lj8) 


155 „ 270 


( ,. i2a) 


220 „ 240 


1, ( 1, ^^a) 


180 „ 230 


Ester value 


35 ,, 75 


Ester value .... 


30 „ 175 


Ash .... 


0-2 „ 1-5% 


Loss at 100° 


4 .1 9% 


Methyl value (by /3) . 


28-5 „ 43-5 


Ash 


0-2 „ 1-5% 


(Should be soluble in alcoho 




Methyl value (by /3) . 


13 „ 25-5 


with little residue, at mosi 




(Should be soluble to the 




5% vegetable tissue.) 




extent of 70 to 80% in alcohol.) 





Colophony. 



Solubility. 



Acid value (by al) 
I. ( I, «2a) 

Sp. gr. 
Loss at 100° 
Ash . 

■\retvl fh /Ti /■'^^''^ value 

y K y J 1^ Saponification value 
Carbonyl value (by /2) 
Methyl value (by /3) 

(Its solution in acetic acid gives a 
fine red coloration with sulphuric acid.) 



145 to 180 



145 

1-045 

0-0 

0-2 

155-82 

251-21 

0-54 



185 

1-085 

0-5% 

1-2% 

1.55-84 

274-94 

0-56 



Alcohol 

Oil of turpentine 
Essential oils 
Acetone 
Ether 

Chloroform 
Methyl alcohol . 
Amyl alcohol . 
Ethyl acetate 
Benzene . 
Carbon bisulphide 
Petroleum naphtha 
Light petroleum 
spirit 



Completely 
soluble 



Partially 
soluble 



CHARACTERISTIC VALUES 



219 



Copal (Zanzibar). 



Acid value (by al) 


35 to 95 


( „ «2a) 




60 „ 65 


Loss at 100° 




0-5 „ 2-5% 


Ash 




0-25 „ 2-0% 


\ ^ ^ /-u L^\ r Acid value 
Acetyl (by /fl) (saponification value . 




77^1 \ on the soluble 
203-29 / portion 


( /I") /^'^'^ value 
" <.>'-' 1^ Saponification value 




210-10 to 221-14 \on the insoluble 
203-94 „ 231 -27 J portion 




Carbonyl value (by X-2) .... 




0-61 


Solubility. 




Natural. 


SheUed. 


Alcohol 


Insoluble 


Almost soluble 


Ether . 










Partially soluble 


Partially soluble 


Methyl alcohol . 










Insoluble 


Insoluble 


Amyl alcohol 










Slightly soluble 


Partially soluble 


Benzene 










Partially soluble 


Almost completely soluble 


Petroleum spirit . 










Insoluble 


Insoluble 


Acetone 












Almost soluble 


Glacial acetic acid 










Partially soluble 


Partially soluble 


Chloroform . 




. 










Carbon bisulphide 










Insoluble 


Almost soluble 


Oil of turpentine . 










Partially soluble 


M 


Cajuput oil . 










Completely soluble 


Completely soluble 


Chloral hydrate (80% solution) . 


Quite insoluble 


Quite insoluble 



Dammar. 



Acid value (by al) 

( n «2a) 

Loss at 100° 

Ash 

A . 1 ,-u 1.1 \ f Acid value .... 
Acetyl (by /51)|s,p,„ifi,,tion value . . 


20 to 35 
20 „ 30 

0-1 „ 1% 

0-01 „ 0-1% 

50-52 „ 51-80 

132-08 „ 134-86 



Guaiacum. 



Acid value 


(by al) . 




20 


to 45 


11 


( „ «2a) 


• 


70 


,. 97 


Ash 


• • 


• • 


2- 


10% 


Acetyl (by ^1) { ^f^ 


value . 
value . 


13 to 23 
163 „ 193 


Methyl va 


lue (by /f3) 


• • 


73 


„ 84 



Solubility. 



Alcohol . at least 80% 
Water . . . 3 to 5% 
Petroleum spirit 0-06 ,, 10% 
Ether . . . 22 „ 91% 
Benzene . . 20 „ 90% 
Carbon bisulphide 12 „ 37% 

Chloral hydrate (60 and 80% 
solutions) .... 



Soluble 



Almost 

completely 

soluble 



220 



RESINS, BALSAMS, AND GUM-RESINS 



Mastic (Levant). 







Solubility. 


Acid value (by al) . 


50 to 70 


Alcohol .... 


Partially sol. 


( „ «2a) 


44 „ 66 


Ether . 




Soluble 


Loss at 100° , . . . 


0-9 „ 1-5% 


Methyl alcohol . 




Partially sol. 


Ash 


0-1 „ 0-2% 


Amyl alcohol 




Soluble 


Methyl value (by JtS) 


„ 1-9 


Benzene 

Petroleum spirit . 
Acetone 

Glacial acetic acid 
Chloroform . 
Carbon bisulphide 
Oil of turpentine . 




1' 

Insoluble 

Partially sol. 

It 

11 
Slightly sol. 
Partially sol. 






Chloral hydrate (60 to 80% 








solution) .... 


'» 



Pine Resin. 





SolubUity. 


Acid value (by «1) . 
Saponification value (by iJla) . 
Ester value .... 
Loss at 100° .... 
Ash 

Acetyl (by «){t:j?;£ : 


100 to 160 

150 „ 190 

10 „ 30 

5 to 12-5% 

1% 
155-27 to 158-48 

222-86 „ 230-75 


Alcohol (90%) . 
Chloroform . . 
Ethyl acetate . 
Benzene . 
Carbon bisulphide 
Ether 

Oil of turpentine 
Petroleum spirit 




Completely sol. 
11 
11 
■I* 
»i 
1* 
Partially sol. 



Sandarac. 





Solubility. 


Acid value (by al) . 


95 to 155 


Absolute alcohol 




Completely sol. 


(by a2a) 


130 „ 160 


Ether . 




II 


Loss at 100° .... 


0-04 „ 0-2% 


Amyl alcohol . 




1* 


Ash 


0-1 „ 2% 


Methyl alcohol 




Partially sol. 


Ace.y.(by.0(^,fvat': 


166 „ 170 


Acetone . 




Completely sol. 


239 „ 252 


Chloroform 


, 


Partially sol. 


Carbonyl value (by >f2) . 


0-43 „ 0-74 


Essential oils . 
Benzene . 

Glacial acetic acid . 
Carbon bisulphide . 




'1 

Almost insol. 
Partially sol. 
Almost insol. 






Chloral hydrate 


(60% 


/ Almost com- 
\ pletely insol. 






solution) 








Petroleum spirit 




Partially sol. 



Australian samples are more soluble in petroleum spirit than the 
above African sandarac. 



CHARACTERISTIC VALUES 



221 



Storax. 





Solubility. 


Acid value (by al) . 
Saponification value (by dl^ . 

(ii^la). 
Ester value .... 
Loss at 100° .... 

Ash 

Methyl value (by y63) 


35 to 180 

130 „ 250 
100 „ 190 
70 „ 185 
5 „ 40% 
0-0 „ 1-5% 
3-6 „ 4-5 


Alcohol . 
Ethyl acetate . 
Chloroform 
Ether 
Benzene . 
Oil of turpentine 
Carbon bisulphide 
Petroleum spirit 




f Almost com- 

\ pletely sol. 

Partially sol. 

11 

II 

II 

II 

II 



Turpentine. 



1. Ordinary Turpen- 
tine. 

Acid value (by al) . 
Saponification value ((^la) 
Ester value 

Carbonyl value (by /f2) . 

(This turpentine hardens 
with calcium hydroxide.) 

2. Larch Turpentine 

Acid value (by al) . 
Saponification value (by 61a) 
Ester value 

(This turpentine does not 
harden with calcium hy- 
droxide.) 



110 to 145 



108 




180 


2 




60 


123 




126 


187 




217 


0-28 




0-57 



65 to 100 

85 „ 130 

,, 55 

70 „ 72 

179 „ 191 



Solubility, 



Alcohol (90 %) 

Ether 

Chloroform 

Ethyl acetate . 

Benzene . 

Oil of turpentine 

Carbon bisulphide 

Petroleum spirit 

Alcohol . 
Ether . 
Methyl alcohol 
Amyl alcohol . 
Benzene . 

Petroleum spirit 

Acetone . 
Glacial acetic acid 
Chloroform 
Ethyl acetate . 

Carbon bisulphide 

Oil of turpentine 



Completely sol. 



/ Almost com- 

\^ pletely sol. 

Partially sol. 

Soluble 



f Almost com- 

^^ pletely sol. 

Soluble 



( Almost com- 
^^ pletely sol. 
Completely sol. 



III. GUxM Resins. 
Ammoniacum. 



Solubility. 



Acid value (by al) 
( „ a3) . 

.._ .( .1 «27) 
Saponification value (by 31/3) 
Total sap. value (by i2p') 
Ester value 
Resin value 
Loss at 100° . 
Ash 
Methyl value (by iS) 



55 to 135 

100 „ 200 

80 „ 105 



145 



235 

155 
100 



99 

60 

145 „ 162 
2-0 „ 15% 

1 
8-6 



7-5% 
11 



Partially soluble in all indifferent sol- 
vents. Alcohol dissolves 90%, water up to 
20%. Galbanum is tested for by boiling 
5 g. of the ammoniacum, as finely divided 
as possible, in a dish with 15 g. hydrochloric 
acid (sp. gr. 1*19) for fifteen minutes, 
filtering through a double moistened filter, 
and carefully adding to the clear filtrate 
an excess of ammonia. The presence of 
galbanum is shown by the characteristic 
blue fluorescence of umbelliferon in reflected 
light. 



222 



RESINS, BALSAMS, AND GUM-RESINS 



Galbanum. 





Solubility. 


Acid value (by al) . 


5 to 70 


As for ammoniacum. Ash 


not to exceed 


( ,, «3) . 


72 „ 115 


10%. 




( n «27) 


20 „ 70 






Saponification value (by il^ . 


75 „ 245 






Total sap. value (by 62^') 


107 „ 123 






Ester value .... 


50 „ 180 






Resin value .... 


115 „ 136 






Loss at 100° .... 


1 ,, 31% 






Ash ..... 


1 „ 30% 






Methyl value (by -^3) . 


3-7 







Myrrh. 





Solubility. 


Acid value (by al) . 
Saponification value (by il^) . 

( M ^17) . 

Ester value 

Ash 

Methyl value (by i3) 


60 to 70 
159 „ 216 
220 „ 230 

95 „ 145 

1 „ 10% 
3-6 „ 4-5 


Partially soluble in all indifferent 
solvents. Water should not extract more 
than 50%, and alcohol not less than 

35%. Ash not to exceed 7%. 



Olibanum. 



Acid value (by al) 

„ (by ^2^) 

Saponification value (by Sl^') . 

( „ ^517) . . 
Ester value ...... 

Carbonyl value (by ,^2) .... 

Methyl value (by /f3) . . . . 


45 to 60 

30 „ 50 

65 „ 120 

110 „ 120 

6 „ 60 

0-36 

5-3 to 6-4 



Literature. 



DiETERICH, K. — Analyse der Harze, Balsame, unci Gummiharze nebst ihrer Chemie 

und Pharmacognosies 1 900. 
TSCHIRCH, A. — Harze u. Harzbehdlter, 2nd edition, 1906. 



DRUGS AND GALENICAL PREPARATIONS 

By K. DiETERiCH, Ph.D., Lecturer on Pharmaceutical Chemistry, The Royal 
Veterinary High School, Dresden. English translation revised by 
Frederick B. Power, Ph.D., LL.D,, Director of the Wellcome Chemical 
Research Laboratories, London. 

Drugs are generally considered to comprise all those crude products 
which represent either the dried parts of plants or plant extracts, and 
which serve as initial material for the manufacture of various important 
pharmaceutical or medicinal preparations. The fact that drugs, to a 
large extent, only come into the hands of the manufacturer as 
secondary or even more completely altered products, is due to the 
chemical changes^ which always take place in connection with their 
production, whether these changes be unintentional or otherwise. As 
a result, even with consideration of differences in the character of the 
soil, drugs always vary in composition, and methods for their examina- 
tion and valuation have therefore become necessary. The standards 
resulting from such methods of examination, as in the case of the 
resins, can, however, only be expressed by figures denoting the maximum 
and minimum limits ; for although pharmaco-chemistry has made 
great progress, we do not know as yet the constituents, either active or 
inactive, of many drugs, to say nothing of being able to determine 
their active principles quantitatively. Even with such drugs as contain 
alkaloids that are known and can be quantitatively determined, it must 
be taken into consideration that the presence, for example, of a certain 
proportion of alkaloid does not always afford a guarantee for the good 
quality and purity of the drug. The conditions with regard to the 
galenical preparations made from the drugs are similar, but for these 
many other analytical factors have become available as the result of 
experience. 

Drugs in a more extended sense, that is, those which are not of 
vegetable origin, and also those drugs and preparations for which 
complete quantitative tests are given in the Pharmacopoeia, have not 
been included in this account of the subject. Furthermore, other 
drugs have been excluded which are more correctly designated as crude 

^ Cf, K. Dieterich, " On the chemical changes in the production of Drugs," Helfenberger 
Annalen^ 1896, pp. 9-20, 

223 



224 DRUGS AND GALENICAL PREPARATIONS 

products, such as the fats, oils, waxes, paraffins, and ceresins, since 
they are dealt with in other Sections. 

In view of the large number of drugs which are now technically 
utilised on a large scale, and the limitations of space, it has naturally 
only been possible to include here the more important. The present 
standards of value and the requirements are in accordance with experi- 
ence, and such as are recorded in the numerous works on pharmaceutical 
chemistry and pharmaco-chemistr}'. 



^.— DRUGS. 
Gambir. 

PALE CATECHU. CATECHU PALLIDUM. TERRA JAPONICA. 

An extract prepared from the leaves and twigs of Ourouparia 
Gambir (Hunter), Baillon. 

Gambir and Catechu are frequently confused, but, although similar 
in character, they are recognised in commerce as distinct products and 
are obtained from totally different botanical sources. The British 
Pharmacopoeia under the title of Catechu recognises the above-defined 
product, to which the United States Pharmacopoeia gives the title of 
Gambir. The fourth edition of the German Pharmacopoeia included 
both of the above-mentioned products under the title of Catechu, bu.t 
in the present edition the term is restricted to the so-called Black 
Catechu or Cutch. 

(a) Reaction for Idetitity (according to K. Dieterich). — If to 3 g. 
of gambir there be added 25 c.c. oi N\i aqueous potassium hydroxide and 
50 c.c. of light petroleum (sp. gr. O/OO at 15^), and the whole shaken 
a few times in a glass separating funnel, after the separation of the two 
layers the light petroleum will show in reflected light a green fluorescence, 
increasing in intensity according to the time of action of the alkali 
(gambir-fluorescin). 

If to the dilute alcoholic solution a solution of ferric chloride be 
added, an intense green coloration will be produced, which persists for 
some time. 

(b) Plant Residues. — If 20 parts of gambir be extracted with 200 
parts of boiling alcohol, the insoluble residue, dried at 100', should 
amount to not more than 6 parts, or 30 per cent. 

(c) Determination of Ash. — i g. of gambir is carefully incinerated, 
and the residue heated until, after cooling in a desiccator, a constant 
weight is obtained. Both the British and United States Pharmacopoeias 
require that gambir should yield not more than 5 per cent, of ash. 



CATECHU. ERGOT 225 



Pegu Catechu. 



BLACK CATECHU. CATECHU NIGRUM. CUTCH. 

An extract prepared from the heartwood of Acacia Catechu (Linne 
fil.), Willdenow. 

The following methods of examination and requirements are those 
of K. Dieterich and of the German Pharmacopoeia : — 

(a) Reaction for Identity. — If to a solution of Pegu catechu in dilute 
alcohol a solution of ferric chloride be added, a green coloration ensues 
which quickly changes to brown, and a precipitate is formed which gives 
a bluish-violet colour with alkalis. 

Pegu catechu does not give the fluorescence reaction of gambir. 

(b) Plant Residues. — The plant residues, determined by the method 
given under gambir, should not exceed 30 per cent. 

(c) Determination of Ash. — If this determination be conducted as 
given under gambir, Pegu catechu should yield not more than 6 per cent, 
of ash. 

Ergot. 
ergota. secale cornutum. 

(a) Determination of Extract, — To 10 g. of the finely crushed drug 
100 c.c, of water are added, and the mixture allowed to stand for 
twenty-four hours in a closed vessel. 20 c.c. of the filtered liquid are 
then evaporated in a tared porcelain dish to dryness, and the residue 
heated at 100" until the weight is constant. The weight of dry 
extract, multiplied by fifty, expresses the percentage of water-soluble 
extract yielded by the drug. 

(b) Determination of Alkaloid (according to C. C. Keller). — 25 g. 
of dry powdered ergot are extracted in a glass percolator with light 
petroleum. When nothing more is removed by this solvent, the drug 
is dried at a gentle heat, and brought into a tared, dry flask of 
250 c.c. capacity. To the powder 100 g. of ether are added, and, after 
ten minutes, milk of magnesia, prepared by mixing i g. of calcined 
magnesia with 20 c.c. of water. The whole is shaken continuously 
and vigorously until the ergot has agglomerated and the liquid becomes 
clear. The shaking is then frequently repeated for half an hour, 
after which 80 g. of the ethereal liquid, representing 20 g. of the drug, 
are decanted. This solution is shaken three times in a separator with 
25, 15, and 10 c.c. respectively of 0-5 per cent, hydrochloric acid. If 
the extraction is not then complete, the liquid is shaken once or twice 
more with 10 c.c. of 0-5 per cent. acid. The acid solution is shaken 
with an equal volume of ether and an excess of ammonia, and this 
extraction repeated twice with less ether. The ethereal liquids are 
united, transferred to a tared flask, and the solvent removed. After 

III P 



226 DRUGS AND GALENICAL PREPARATIONS 

treating the residue twice with a Httle ether, and evaporating the 
latter, the flask with its contents is finally dried and weighed. The 
weight of dry residue, multiplied by five, expresses the percentage of 
alkaloid present in the ergot. 

The following minimum and maximum values have been obtained : — 

Extract . , . 1250 to 17-84 per cent. 

Alkaloid . . . o-io „ 034 „ 

Requirements. — Ergot has an oily, unpleasant taste, and when mixed 
with 10 parts of hot water should develop the odour peculiar to it, 
but this should be neither ammoniacal nor rancid. It should yield 
the largest possible amount of extract and of alkaloid.^ 

Isinglass. 

ICHTHYOCOLLA. COLLA PLSCIUM. 
{According to K. Die tench.) 

(a) Preparatio7i of the Material. — The kinds of isinglass which are 
capable of being divided into small pieces by means of shears, or a 
knife, etc., are cut into strips i cm. in width, and these again into squares 
of i cm. When the isinglass is very hard and cannot be divided in 
this manner, it is best ground in a mill to a powder, which, however, 
should be as coarse as possible, as the production of a fine powder 
renders the subsequent operation of filtering extremely difficult. 

(b) Dcternii)iation of the Moisture. — About 5 g. of the isinglass, 
divided into small pieces as described above, is heated in a drying 
oven at ioo°-i05° until the weight is constant. 

(c) Determination of the Ash. — The perfectly dried isinglass remain- 
ing from the determination of the moisture is heated by a small flame 
in a fume chamber having a good draught until the material ceases to 
emit dense vapours, which have the smell of burnt horn, and there is no 
longer a strong intumescence. All possible care should also be taken 
that the isinglass does not burn on to the vessel, so that after a while 
a brownish black carbonaceous mass remains which is somewhat 
readily combustible. By the application then of a larger flame, and 
eventually moistening the material once with water, it ma)- completely 
and quickly be reduced to a light brown ash. 

(d) Determination of Potassium Carbonate in the Ash. — The ignited 
residue obtained by the determination of the ash is taken up with 
hot water, transferred to a small filter, and washed with about 75-100 
c.c. of boiling, distilled water. The filtrate, after the addition of a 

' For recent investigations concerning tlie allviiloids of ergot cf. J, Cliem. Soc.^ 1907, 
91. 337 ; 19091 95. "23 ; 1910, 97, 284, 2592 ; 191 1, 99, 2336 ; /. Pharm. Chim., 1909 [vi.], 
30. 145- 



ISINGLASS 227 

little tropreoHn or methyl orang-e, is titrated with A^io hydrochloric 
acid, and the amount of potassium carbonate calculated either on the 
original substance or on lOO parts of ash. 

(e) Deterviination of the portions soluble and itisolnble in Boiling 
Water. — lo g. of the finely divided isinglass are placed in a tall 

enamelled vessel, preferably an internally enamelled litre measure, with 
a spout, since glass beakers cannot be used for this purpose. About 
500 c.c. of water are then added, and the mixture kept in a steam-bath 
or water-bath until the isinglass floats for the most part on the 
surface, so that it cannot burn on to the bottom of the vessel by the 
subsequent treatment. It is then heated to boiling over a free flame, 
and the boiling continued until the intense frothing has ceased or 
abated. During the evaporation the froth, mixed with the impurities 
contained in the isinglass, is firmly deposited on the sides of the 
vessel. At this stage 400 c.c. of hot distilled water are added, and 
the liquid evaporated to about 300 c.c. Pieces of the isinglass which 
may adhere to the sides of the vessel are detached from time to time 
by means of a glass rod, and brought into the boiling liquid. The 
vessel is then removed from the burner, placed on a steam-bath, and 
the solid material allowed to deposit, after which the liquid is decanted 
as completely as possible into a graduated litre flask. About 800 g. 
of boiling water are then added, the mixture again heated over a free 
flame, and then evaporated to about 200 c.c, after which it is allowed 
to deposit, and the liquid decanted as before. This operation is 
repeated altogether three or four times, until the litre flask is about 
nine-tenths filled. The flask, especially during warm weather, should 
be kept hot on a steam-bath or water-bath during the entire pro- 
cedure, in order to prevent the solution from spoiling. The vessel 
employed for heating is cleaned from all adhering particles of isinglass 
by means of a glass rod over which a piece of rubber tubing is drawn, 
and a little water, and the entire residue finally washed into the 
litre flask. The contents of the flask are then cooled to 15", filled up 
to the mark, and the whole thoroughly shaken and filtered. 50-100 
c.c. of the filtrate, which is more or less opalescent, are evaporated 
in a tared dish, the residue dried at loo'-ios" until the weight is 
constant, and calculated for the percentage of substance soluble in 
boiling water. The sum of this percentage and that of the moisture, 
subtracted from lOO, gives the percentage of substance contained in 
the isinglass which is insoluble in boiling water, 

(f) Swelling Value and Gelatinising Power. — To determine the 
swelling value 10 g. of the isinglass are placed in a tared, enamelled 
litre measure, 800 c.c. of hot water added, and, together with a glass rod 
which is weighed at the same time, the mixture evaporated on a steam- 
bath, with frequent stirring, to a total weight of about 510 g. If 



228 DRUGS AND GALENICAL PREPARATIONS 

gelatinisation does not ensue, when completely cold, an additional 50- 
100 g. of water are evaporated, and it is again allowed to cool. When 
the point is thus determined at which a jelly is formed, the whole is 
weighed. If, for example, the weight is found to be 370 g., the 
gelatinising power is i : 36, or the swelling value is 36. 

Since it has been found by experience that the gelatinising power 
is affected by heating over a free flame to boiling and subsequent 
evaporation, a steam-bath should be employed so that the temperature 
does not exceed loo^ 

(g) Deterniination of the Fat. — 10 g. of the finely divided isinglass 
are weighed into an extraction thimble, placed in a Soxhlet apparatus, 
and extracted for three hours with ether of sp. gr. 0720. The contents 
of the extraction flask are then evaporated, and dried for a short time 
at 100' until the weight is constant, the weight of the flask itself having 
been previously determined. The contents of the extraction thimble 
are also dried, and, after all the ether has evaporated, used for the 
determination of the glutin, 

(h) Deterniinatio)i of the Collagen. — The combined weights of the 
soluble and insoluble portions, minus the fat, expresses the amount of 
collagen. 

(i) Deter minatioji of the Crude Glutin. — The dried contents of the 
extraction thimble, remaining from the determination of the fat, 
contains the so-called collagen, that is, the pure gelatin-yielding 
tissue freed from fat, and this is used for the determination of the 
glutin as follows : — The contents of the thimble are completely extracted 
with boiling water, in the same manner as described for determining 
the portion of the isinglass soluble in boiling water (cf. e). 500 c.c. of 
the filtrate which is finally obtained, corresponding to 5 g. of the 
isinglass deprived of fat, i.e. collagen, are placed in an accurately 
weighed beaker, and evaporated to about 50 c.c. To the solution, 
while still warm, 200-300 c.c. of absolute alcohol are gradually added in 
a thin stream, and the precipitate thus produced allowed to stand for 
at least twelve hours, or until the supernatant liquid has become 
perfectly clear. Although the glutin is usually precipitated as an 
extremely viscid, white mass, opalescent on the surface, it is best to 
bring the mixture on to a small, weighed filter. The filtrate, together 
with the alcohol used for washing the glutin and the filter, are then 
evaporated in a tared dish, the residue being finally dried and weighed 
(extractive matter not precipitable by alcohol). 

It may be noted that in the technical preparation of glutin the 
isinglass is usually treated with dilute hydrochloric acid before being 
deprived of fat, in order to remove inorganic constituents. This 
procedure cannot be adopted in the cjuantitativc determination of 
glutin, for the reason that other constituents would be dissolved 



ISINGLASS 229 

together with the inorganic substances, and the action of hydrochloric 
acid is too strong for analytical purposes. If it is desired to ascertain 
the nature of the small amount of inorganic matter present, the ash 
yielded by the glutin is determined. 

(k) Determination of the Acid Value. — If the filtrate obtained by the 
determination of the soluble portion of the isinglass, when tested with 
sensitive litmus paper, gives a distinctly acid reaction, the acid value of 
the solution may be ascertained as follows : — 2 g. of isinglass, together 
with 100-150 c.c. of distilled water, are placed in a flask of 200 c.c. 
capacity, the liquid heated for about three hours on a steam-bath, then 
brought once to boiling over an open flame, allowed to cool, filled up 
to the mark, and filtered after being well shaken. 50 c.c. of the filtrate 
are finally titrated with Njio aqueous potassium hydroxide, using 
phenolphthalein as the indicator. 

(1) Determination of the Iodine Value} — Since isinglass belongs to 
the albuminoids, or albumen-like substances, its property of absorbing 
iodine may be used for its identification and the detection of adultera- 
tions, as in the case of albumen itself. The determination of the iodine 
value may be carried out as follows : — 50 c.c. of the same filtrate as that 
employed for the determination of the acid value or of the filtrate used 
for determining the soluble portion of the isinglass, representing 0-5 g. 
of the latter, are mixed with 20 c.c. of an N\\o solution of iodine in 
potassium iodide in a glass-stoppered bottle of 500-750 c.c. capacity. 
The mixture is then well shaken, allowed to stand for twenty-four 
hours, and the excess of iodine titrated back with A710 sodium 
thiosulphate, using starch as an indicator. The number of c.c. of N\io 
iodine solution used, multiplied by 0-012697 and 200 respectively, gives 
the iodine value of the sample. 

(m) Test for Sulphur. — The test for sulphur is important, inasmuch 
as isinglass is often artificially bleached with sulphurous acid, and such 
a product is generally not so good as that obtained by natural methods. 
The test consists in fusing the isinglass with a mixture of potassium 
nitrate and sodium carbonate, and testing the aqueous extract of the 
fused mass for sulphate in the usual manner, 

(n) Test for Starch. — The test for starch may also serve as one 
for identity, since pure isinglass gives no reaction for starch, whereas 
artificial products may do so. To the aqueous solution a little solution 
of iodine in potassium iodide is added, when pure isinglass will show a 
reddish-brown, but no blue coloration. 

(o) Determination of the Optical Rotation of the Glutin Solution. — 
The aqueous glutin solution is laevo-rotatory, and the optical rotation 
is therefore also to be determined as proof of identity of a natural 
isinglass. 

1 Cf. K. Dieterich, Hel/enberger Annalen, 1897, pp. 1-29. 



230 



DRUGS AND GALENICAL PREPARATIONS 



Table 38. 
Analytical Values for Isinglass (K. Dieterich). 

(Expressed in round numbers.) 









American : 


Adulterated 




Rnssian : 
Salianaky, 


Chinese. 


Brazilian, 
Venezuelan, 


Saliansky, 

iniprepnated 

with glue. 




Beluga, Samovy. 




Jlaracaibo, 
and scraps. 


Moisture . 


13 10 20 p. c. 


11 to 17 p. c. 


13 to 18 p.c. 


16 p. c. 


Ash . 


O'O to 1"7 p. c. 


0-9 to 2-3 p. c. 


1 to 3-7 p.c. 


0-6 p.c. 


Potassium carbonate in 
100 parts of ash . 


1 8 to 33 p. c. 


32 to 53 p. c. 


6 to 37 p.r. 


72 p.c. ! 


Soluble portion 


65 to 81 p. c. 


68 to 86 p. c. 


59 to 75 p. c. 


82 p. c. 


Insoluble ponion 


1 to 19 p. c. 


2 to 15 p.c. 


9 to 25 p. c. 


1*5 p. c. 


Swelling value . 


to 49 


14 to 25 


16 to 55 


25 


Fat . 


0-1 to 1-2 p. c. 


0-1 to 1-2 p.c. 


0-1 to 0-8 p. c. 


0-3 p.c. 


Collagen . 


79 to 85 p. c. 


81 to 88 p. c. 


80 to 87 p. c. 


83 p. c. ! 


Crude glutin 


66 to 82 p. c. 


69 to 74 p. c. 


66 to 75 p. c. 


82 p c. ! 


Acid value 


to 6-0 





to 2-76 


3-8 p. c. ! 


Iodine value 


19 to 45 


39 to 46 


30 to 47 


37 


Ash of crude glutin . 


. 0-4 to 0-7 p. c. 


0-67 p.c. 


0-4 to 0-7 p.c. 


0-4 to 0-7 p.c. 


Optical rotation of crude 
glutin . 


I laevo 


laevo 


laevo 


\xvo 


) 








Test for sulphur 


positive 


positive 


positive 


positive 



OriUM. 

{According to K. Dieterich and the German Pharmacopaia!) 

(a) Dctcrniinatioji of Moisture. — 2 g. of the opium are heated in a 
drying oven at 100° until the weight is constant. 

(b) Deter jumatioji of Ash. — The dried opium is incinerated, and the 
residue ignited until the weight remains constant. 

(c) Determination of MorpJdne. — The following method is that of the 
German Pharmacopoeia: — 7 g. of opium, dried at 60^ and in moderately 
fine powder, are triturated with 7 g. of water, the mixture being then 
washed with water into a flask and the total weight made up to 61 g. 
by the further addition of water. After having stood for an hour with 
frequent shaking, the mixture is transferred to a dry, folded filter of 
10 cm. diameter. To 42 g. of the filtrate ( = 488 g. opium) there is then 
added 2 c.c. of a mixture of 17 g. solution of ammonia (sp. gr. 0960) and 
83 g. of water, and the whole filtered immediately through a dry, folded 
filter into a flask. To 36 g. of the filtrate ( = 4 g. opium) are then added, 
with agitation, 10 c.c. of ethyl acetate and another 5 c.c. of the above- 
mentioned dilute ammoniacal liquid. After corking the flask, the 
contents are shaken for ten minutes, then 20 c.c. more of ethyl acetate 
added, and the whole allowed to stand for a quarter of an hour with 
occasional gentle agitation. The ethyl acetate layer is then first 



OPIUM 231 

transferred as completely as possible on to a smooth filter of 8 cm. 
diameter, lO c.c. of ethyl acetate added to the aqueous liquid remaining 
in the flask, the mixture agitated for a moment, and the ethyl acetate 
layer then again brought on to the filter. After the ethereal liquid has 
ceased to pass, the aqueous solution is poured on the filter, without 
regard to the crystals adhering to the sides of the flask, and the filter as 
well as the flask washed three times with water which has been saturated 
with ether, using 5 c.c. each time. When the liquid has thoroughly 
drained from the flask, and ceased to drop from the filter, both the flask 
and filter are dried at 100°. 

In order to determine the amount of morphine gravimetrically, the 
dried contents of the filter are transferred to the previously tared flask 
by means of a camel's-hair brush, and the whole heated at 100° until the 
weight is constant. The weight of substance, when multiplied by 25, 
then represents the percentage amount of anhydrous morphine in the 
opium. The German Pharmacopoeia directs, however, that the morphine 
shall ultimately be determined by the following volumetric method : — 
The crystals of morphine, as obtained above, are dissolved in 25 c.c. of 
Njio hydrochloric acid, the solution poured into a graduated flask of 
100 c.c. capacity, the filter, flask, and stopper then carefully washed with 
water, and the solution finally diluted to the measure of 100 c.c. 50 c.c. 
of this solution, representing 2 g. of powdered opium, are placed in a 
flask of about 200 c.c. capacity, and about 50 c.c. of water added, 
together with so much ether that the latter forms a layer about i cm. in 
depth. After the addition of 10 drops of iodo-eosine solution, Njio 
potassium hydroxide is allowed to flow into the liquid, shaking actively 
after each addition, until the lower aqueous layer has assumed a pale 
red colour. For this purpose not more than 4-1 c.c. of Njio potassium 
hydroxide should be required, so that at least 8-4 c.c. of A^io hydro- 
chloric acid are used for the neutralisation of the morphine present. 
This corresponds to a minimum of 12 per cent, of morphine in the 
opium, since i c.c. Njio hydrochloric acid = 0-02852 g. of morphine, 
Ci7Hjg0.3N, with iodo-eosine as the indicator. 

The British Pharmacopoeia (1898) requires that opium dried at 100° 
should contain about 10 per cent, of anhydrous morphine. The 
United States Pharmacopoeia (eighth revision) specifies that opium in 
its normal moist condition should contain not less than 9 per cent, of 
crystallised morphine, Ci7H^,,03N, H2O, or, when dried at 85° not less 
than 12 per cent, nor more than 12-5 per cent, of crystallised morphine. 
It should be noted, however, that these percentages of morphine are 
based upon the methods of assay prescribed by the respective 
pharmacopoeias, since different methods are likely to yield somewhat 
divergent results. 

(d) Microscopic Test, especially for starch. 



232 DRUGS AND GALENICAL PREPARATIONS 

The following variations in composition have been found in the 
examination of opium : — 

Moisture . . . 7-35 to 24-13 per cent. 

Ash . . . . 3-55 „ 5-49 

Aqueous extract . . 45-00 „ 45-25 „ 

Morphine . . . 9-98 „ 15-82 „ 

Vegetable Drugs. 

The method of examination of vegetable drugs should be of an 
individual character, in accordance with the purpose for which the 
drug is to be used, and with due consideration of the preparation that 
is to be made from it. In cases where official preparations are 
concerned the method of testing adopted should be in accord with 
the respective directions given in the current pharmacopceias. Since 
these examinations only involve the determination of comparative 
values, and not exact figures for the purpose of manufacture, H. Mix 
and K. Dieterich regard it as sufficient to extract the drug once 
only, and to allow not more than forty-eight to sixty hours for the 
operations of expression, filtration, evaporation, and drying to constant 
weight. 

I. BARKS. 

Cascara Sagrada. 

The dried bark o{ Rkaninus PursJiimia, DC. 

DetenntHntt'oH of Extract. — The bark is extracted by the following 
methods, according as it is to be used for the preparation of 
(i) aqueous extract ; (2) alcoholic extract ; or (3) liquid extract. 

1. As indicated under Ergot (p. 225). 

2. As indicated under Flowers (III.), cither with 68 per cent, 
alcohol, or with a mixture of 2 parts by weight of 90 per cent, 
alcohol and 3 parts of water. 

3. Like the preceding, with a mixture of i part by weight of 
90 per cent, alcohol and 2 parts of water. 

The German Pharmacopoeia requires that the bark, when completely 
extracted with a mixture of 3 parts of alcohol and 7 parts of 
water, should yield at least 24 per cent, of extract, and that, when 
incinerated, it should leave not more than 6 per cent, of residue. 

Cascarilla. 

The dried bark of Crot07i Elutcria, Bennett. 

Determination of Extract. — As described in the introduction to 
Leaves (p. 239), in the proportion of 10 : 200. 



VEGETABLE DRUGS 233 



Cinchona. 



The British, United States, and German Pharmacopceias all 
recognise the dried bark of the stem and branches of cultivated 
plants of Cinchona succirubra, Pavon. In addition to the latter the 
United States Pharmacopoeia, under the general title of CincJiona, 
comprehends the dried bark of Cinchona Ledgenana, Moens, C. Calisaya, 
Weddell, C. officinalis, Linne, and hybrids of these with other species 
of CincJiona. 

(a) Aqueous Extract — lo g. of the finely powdered bark are 
mixed in a beaker with lOO c.c. of cold water, and the mixture allowed 
to stand for twenty-four hours, with frequent stirring. It is then 
allowed to settle, 20 c.c. of the filtered liquid ( = 2 g. of bark) evaporated, 
and the residue dried until of constant weight. 

(b) Alcoholic Extract. — Proceed as under {a), but with the use of 
68 per cent, alcohol. 

The following yields of extract have been obtained : — 

Dry aqueous extract . . . ir-i to 26-0 per cent. 

Dry alcoholic extract . . . 34.0 „ 39-5 „ 

(c) Determination of Alkaloid. — The following method is that of the 
German Pharmacopoeia : — 

To 12 g. of the finely powdered bark, contained in a flask, are 
added 30 g. of chloroform and 30 g. of ether (sp. gr. 0720), and, after 
vigorous shaking, 5 g. of solution of sodium hydroxide (15 per cent.) 
and 5 g. of water. The mixture is then allowed to stand for three 
hours, with frequent vigorous shaking. 60 g. of ether are subsequently 
added, the whole being well shaken, and, after the liquid has become 
clear, 80 g. of the chloroform-ether mixture ( = 8 g. of cinchona bark) 
are filtered through a dry, well-covered filter into a flask, and about 
two-thirds of the solvent distilled off. The cooled residue is transferred 
to a glass separator (I.), the flask washed three times with a mixture 
of 2 parts of chloroform and 5 parts of ether, using 5 c.c. each 
time, then once with 20 c.c. of dilute hydrochloric acid (containing i per 
cent, of acid of sp. gr. 1-126), these liquids being also brought into the 
separator, and, after the addition of so much ether that the chloroform- 
ether mixture floats on the surface of the acid liquid, the entire 
mixture is vigorously shaken for two minutes. When the liquids have 
become clear, the hydrochloric acid solution is allowed to flow into 
another separator (II.), and the ethereal liquid shaken twice successively 
in the same manner with the above-mentioned dilute hydrochloric acid, 
using 5 c.c. each time. 

To the combined hydrochloric acid liquids are added 5 c.c. of 
chloroform, then a solution of sodium carbonate until the reaction is 



234 DRUGS AND GALENICAL PREPARATIONS 

alkaline, and the mixture at once shaken vigorously for two minutes. 
When the liquids have become perfectly clear, the chloroform extract 
is allowed to flow into another separator (III.), and the alkaline liquid 
shaken three times successively with chloroform, using 5 c.c. each 
time. To the combined chloroform extracts are added 25 c.c. of 
N/io hydrochloric acid, and so much ether that the chloroform-ether 
mixture floats on the surface of the acid liquid, after which the whole 
is well shaken for two minutes. When it has become perfectly clear, 
the acid liquid is filtered through a small filter, moistened with water, 
into a graduated flask of 100 c.c. capacity, the chloroform-ether 
mixture shaken three times successively for two minutes with water, 
using 10 c.c. each time, these aqueous liquids being also passed through 
the same filter, which is finally washed with water, and the entire 
aqueous, acid liquid diluted with water to 100 c.c. 50 c.c. of this 
liquid ( = 4 g. of cinchona bark) are placed in a flask, about 50 c.c. of 
water added, and then a freshly prepared solution of a fragment of 
haematoxylin in i c.c. of alcohol. Subsequently N'lO potassium 
hydroxide solution is added to the liquid, with gentle agitation, until 
the mixture assumes a deep yellow colour, which by vigorous agitation 
quickly passes into bluish-violet. For this purpose not more than 
4-1 c.c. of iV/io potassium hydroxide solution should be required, so 
that at least 84 c.c. Njio hydrochloric acid would be used up for the 
neutralisation of the alkaloids present. This would correspond to a 
minimum of 6-5 per cent, of alkaloids in the bark (i c.c. Njio hydro- 
chloric acid =0-0309 g. quinine and cinchonine, using haematoxylin as 
the indicator). 

5 c.c. of the alkaloid solution which was not used for the titration, 
when mixed with i c.c. of chlorine water, should give a green coloration 
on the addition of solution of ammonia. 

Standards for Alkaloid. — The German Pharmacopoeia requires that 
red cinchona bark, when assayed by the above method, should yield 
at least 6-5 per cent, of alkaloids of the composition C20H04O.2N., 
(quinine) and Cj,,H.2.pN2 (cinchonine), having an average molecular 
weight of 309. The British Pharmacopcjeia requires between 5 and 
6 per cent, of total alkaloids, of which not less than half should consist 
of quinine and cinchonidine, when estimated by the official method. 
The United States Pharmacopoeia requires for Ciuclioua succirubra not 
less than 5 per cent, of anhydrous cinchona alkaloids ; for the species 
mentioned under Cinchona not less than 5 per cent, of total anhydrous 
cinchona alkaloids, and at least 4 per cent, of anhydrous ether-soluble 
alkaloids, when a.ssayed by the official process. 

Since the various pharmacopruias prescribe different methods of 
assay, and the percentage of alkaloids required to be contained in a 
bark is based on a particular method, it is obvious that this is to be 



BARKS 235 

considered in connection with the vakiation of any given species of 
cinchona which is to be used for pharmacopoeial purposes. 

Cinnamon and Cassia. 

The true Cinnamon consists of the dried inner bark of the shoots 
of Cimiauioiimm zeyla?iic?im, Breyne, and is distinguished in commerce 
as Ceylon Cinnamon. 

Cassia bark is obtained from one or more undetermined species of 
CimiauioDiHvi grown in China, and is also known as Chinese Cinnamon. 

The British and German Pharmacopoeias recognise only Ceylon 
Cinnamon, whereas the United States Pharmacopoeia also includes 
Saigon Cinnamon, which is the bark of an undetermined species of 
Cinnmnoviuvi. 

Determination of Extract. — The yield of aqueous extract is deter- 
mined as stated under Ergot, and that of alcoholic extract by the 
method described under Flowers (III.), with the use of 68 per cent, 
alcohol. 

Determination of Aldehyde. — The yield of cinnamic aldehyde may 
be determined by the method of J. Hanus.^ 

The German Pharmacopoeia requires that cinnamon bark should 
yield on ignition not more than 5 per cent, of ash. 

Condurango. 

The probable botanical source of this bark is Marsdenia cundnrango, 
Reichenbach fils. 

Determination of Extract. — When the bark is to be used for the 
preparation of extract, the yield of alcoholic extract is determined as 
under Flowers (III.), with the use of a mixture of 2 parts by weight 
of 90 per cent, alcohol and i part of water. For the preparation of a 
liquid extract it is treated in the same manner, but with a mixture of 
I part by weight of alcohol and 3 parts of water. P^or a tincture the 
extraction is conducted with 68 per cent, alcohol. 

Frangula. 

The dried bark oi Rhammis frangula, Linne. 

Determination of Extract. — The bark is extracted by one of the 
following methods, according to its intended use for the preparation of 
(i) an aqueous extract ; (2) an alcoholic extract; (3) a liquid extract; 
or (4) a tincture. 

(i) It is extracted with cold water in the manner described under 
Ergot (p. 225), or with boiling water as described in the introduction 
to Leaves (p. 239), in the proportion of 10 : 200. 

1 Z. Unters. Nahr. it. Genussin., 1 903, 6, 817 ; /. Soc. Chem. fnd., 1 903, 22, 1 1 54. 



236 DRUGS AND GALENICAL PREPARATIONS 

(2) In the manner described under Flowers (III.), ^vith a mixture 
of 2 parts by weight of 90 per cent, alcohol and 3 parts of water. 

(3) In the same manner, with a mixture of 3 parts by weight of 90 
per cent, alcohol and 7 parts of water. 

(4) In the same manner, but with 6S per cent, alcohol. 

I!. BULBS. 

SquiH. 

Squill consists of the bulb of Urgitiea maritima (Linnc), Baker, 
divested of its dry, membranous outer scales, cut into slices, and dried. 

Determination of Extract. — The squill, in moderately fine powder, is 
extracted with either cold or hot water, or with 68 or 90 per cent, 
alcohol, according to the methods which have been described, and 
adhering as closely as possible to the directions for making the 
respective preparations. 

The German Pharmacopoeia requires that squill shall yield on 
ignition not more than 5 per cent, of ash. 

in. FLOWERS. 
In the case of flowers the alcoholic extract is generally determined 
in accordance with the following method : — 

(a) Alcoholic Extract. — To 10 g. of the ground flowers, contained in 
a flask, are added 100 c.c. of a mixture of i part by weight of alcohol 
and 2 parts of water. The flask is then closed, allowed to stand for 
twenty-four hours, with frequent shaking, and, after the material has 
deposited, the liquid is filtered. 20 c.c. of the filtrate ( = 2 g. of the 
drug) are then evaporated in a tared dish, and the residue dried at 100° 
until the weight is constant. 

(b) The official flowers should conform to the requirements of the 
respective pharmacopoeias. 

Chamomile Flowers. 

The Chamomile Flowers of the British and United States 
Pharmacopoeias consist of the dried flower heads of Anthemis nobilis, 
Linn6, whereas the German Pharmacopoeia recognises only the dried 
flower heads of Matricaria cJianioniilla, Linne, which are commonly 
known as German Chamomile. 

Determination of Extract. — The German chamomile flowers, accord- 
ing to their intended use for the preparation of (i) tincture ; (2) extract 
or syrup ; or (3) oil, are extracted by one of the following methods : — 

(i) As described above, with 68 per cent, alcohol. 

(2) As described above, with a mixture of 2 parts by weight of 90 
per cent, alcohol and 3 parts of water. 



FLOWERS. FRUITS 237 

(3) In the same manner, with 200 c.c. of a mixture of 150 g. of 90 
per cent alcohol and 2 g. of a solution of ammonia (sp. gr. 0-960). 

All extractions of chamomile flowers should be conducted in the 
proportion of 10 g. of the flowers to 200 c.c. of the respective liquid. 

Red Poppy Petals. 

Red Poppy petals are obtained from Papmier Rkoeas, Linne. 

Determmatioii of Extract. — This is conducted according to the 
method described in the introduction to Leaves (p. 239), in the pro- 
portion of 10 : 200, but the temperature of extraction should not exceed 
about 35°-40°, and 0-2 g. of citric acid should be added to 10 g. of the 
red poppy petals or to 200 c.c. of water respectively. 

Rose Petals. 

This title refers to the petals of the Pale Rose or Cabbage Rose, 
which are obtained from Rosa centifolia, Linne. 

Determination of Extract. — The extraction is conducted in the 
proportion of 10 parts of the petals to 200 parts of liquid by one of 
the following methods, according to the use of the petals for the 
preparation of (i) an alcoholic extract ; or (2) for honey of rose. 

(i) By the above general method, with the use of 68 per cent, 
alcohol. 

(2) As described in the introduction to Leaves (p. 239), in the pro- 
portion of 10 : 200. 

IV. FRUITS. 

Buckthorn Berries. 

The fruit of Rhainnns cathartica, Linne. 

Determination of Extract. — The well-crushed berries are extracted 
by the use of 10 parts of berries to lOO parts of solvent, as described 
in the introduction to Leaves (p. 239). 

Capsicum. Spanish Pepper. Cayenne Pepper. 

In the German Pharmacopoeia Capsicum is defined as the dried, ripe 
fruit of Capsicum annuum, Linne, whereas the British and United States 
Pharmacopoeias recognise the smaller fruit of Capsicum minimum, 
Roxb. {C. fastigiatum, Blume). 

Determination of Extract. — According to the intended use of 
capsicum for the preparation of (i) a liquid extract; (2) a tincture; 
or (3) a thick extract, it is extracted with one of the following solvents, 
as indicated under Flowers (III.). 

(i) With 90 per cent, alcohol, 

(2) With 68 per cent, alcohol. 



238 DRUGS AND GALENICAL rilEPARATIONS 

(3) With a mixture of 2 parts by weight of alcohol and 3 parts of 
water. 

The German Pharmacopceia requires that powdered capsicum should 
yield on ignition not more than 6-5 per cent, of ash. 

Elder Berries. 

The fruit of Sanibitcus Jiigra, Linnc. 

Dctcy))n)iation of Extract. — This is conducted as indicated under 
Buckthorn berries. 

Fennel. 

The ripe fruit of Fooniciiluiii capillaccuui^ Gilibert. 

Dctcr)}iination of the Essential Oil (according to K. Dieterich). — 
10 g. of the finely crushed fruit are distilled in a current of steam until 
the distillate (about 500 c.c.) no longer possesses an odour. The 
distillate is then saturated with common salt and allowed to stand for 
twenty-four hours, after which the oil is extracted with 50 c.c. of ether 
by shaking in a separator. The ethereal liquid is filtered through a 
little well-dried salt, the latter subsequently washed with 20 c.c. of ether, 
and the combined liquids allowed to evaporate spontaneously in a beaker 
which is covered with finely perforated filter paper. When the ether 
has completely evaporated, the residue is dried for twelve hours in a 
desiccator, and weighed. 

The yield of essential oil has been found to be from 3-0 to 40 per 
cent. 

The German Pharmacopceia requires that powdered fennel fruit 
should yield on ignition not more than 10 per cent, of ash. 

Juniper Berries. 

The dried, ripe fruit oi ftcniperus communis^ Linne. 

Determination of Extract. — As described in the introduction to 
Leaves (p. 239). 

The juniper berries are previously well crushed, but extracted 
only in the proportion of 10 parts of berries to 100 parts of liquid, 
and the heating for a quarter of an hour in a hot-water bath is 
omitted. 

The German Pharmacopcuia requires that powdered juniper berries 
should yield on ignition not more than 5 per cent, of ash. 

Parsley Fruit. 

The fruit of Caruni Petroseliiinm, Jicnth. et Hook. 

Determination of the Essential 6?// (according to K. Dieterich). — As 
described under Fennel, and according to the Supplement to the 
German Pharmacopoeia, 4th edition. 



HERBS. LEAVES 239 

Poppy Capsules. 

Poppy capsules or heads are the dried, immature fruits of Papaver 
soniniferuni, Linne. 

Detcnnination of Extract. — This is conducted as described under 
Flowers (III.), with lOO c.c. of a mixture of i part by weight of 90 per 
cent, alcohol and 9 parts of water. 

V. HERBS. 

The general directions for the examination of herbs consist in 
determining either the yield of alcoholic extract, as described under 
Flowers (III.), or the aqueous extract, as described under Leaves (VI.). 

When the herbs are to be used for making extracts, the prescribed 
directions for the respective extract should be strictly followed. The 
herbs should be used in a finely cut state. 

Carduus Benedictus (Blessed Thistle). 

The dried leaves and flowering branches of Cnicus benedictus, Linne. 
Dctermmation of Extract. — As described under Alexandrian Senna 
leaves (p. 244). 

Linaria (Common Toad-flax). 

The flowering plant of Linaria vulgaris. Miller. 

Determination of Extract. — As described under Flowers (III.), with 
the use of 100 c.c. of a mixture of 150 g. of 90 per cent, alcohol and 
5 g. of a solution of ammonia (sp. gr. 0-960). 

Marjoram (Sweet Marjoram). 

The leaves and flowering stems of Origanum Majorana, Linne. 
Determination of Extract. — As described under Linaria. 

Milfoil or Yarrow. 

The flowering plant oi Achillea Millefolium, Linne. 

Determi)iation of Extract. — As described under Flowers (III.), with 
a mixture of 2 parts by weight of 90 per cent, alcohol and 3 
parts of water, and in the proportion of 10 g. of herb to 200 c.c. 
of liquid. 

VI. LEAVES. 

The general method for the examination of leaves consists in 

determining the yield of water-soluble extract. The procedure is as 
follows : — 

(a) Determinatioji of Extract. — To 10 g. of the finely cut leaves, 

contained in a tared beaker, 100 g. of boiling water are added, the 



240 DRUGS AND GALENICAL PREPARATIONS 

whole heated for ten to fifteen minutes in a hot-water bath, and allowed 
to stand for twenty-four hours. The amount of evaporated water 
is then replaced, the liquid filtered, 20 c.c. of the filtrate ( = 2 g. of the 
drug) evaporated to dryness, and the residue heated at 100° until 
of constant weight. 

(//>) Those leaves which are officially recognised are also to be 
tested according to the respective pharmacopcuia. 

The examination is somewhat differently conducted with belladonna, 
coca, digitalis, senna, and menyanthes leaves. 

Belladonna (Deadly Nightshade). 
The dried leaves of Atropa Belladonna, Linnc, which, according to 
the German Pharmacopoeia, should be collected from plants growing 
wild and at the time of flowering. 

Determination of Hyoscyamine, C17H.23O3N. — The following method 
is that of the German Pharmacopoeia : — 

To 20 g. of finely powdered belladonna leaves, contained in a 
flask, are added 120 g. of ether, and, after vigorous shaking, 5 g. of 
a solution of sodium hydroxide (15 per cent.) and 5 g. of water. The 
mixture is then allowed to stand for an hour, with frequent and 
vigorous shaking. When the liquid has become perfectly clear, 
60 g. of the ethereal solution (= 10 g. of belladonna leaves) are filtered 
through a dry, well-covered filter into a flask, and about two-thirds 
of the ether distilled off. The cooled residue is transferred to a glass 
separator (I.), the flask washed three times with ether, using 5 c.c. each 
time, and then once with 10 c.c. of dilute h)'drochloric acid (i part 
of acid, sp. gr. 1-126, to 49 parts of water), these liquids being also 
brought into the separator, and the whole shaken vigorously for two 
minutes. When the liquids have become perfectly clear, the hydro- 
chloric acid solution is run into another separator (II.). and the ethereal 
liquid again shaken in the same manner with two successive portions, 
of 5 c.c. each, of dilute hydrochloric acid (1:49), the latter having 
previously been used for the further rinsing of the flask. 

To the combined hydrochloric acid extracts are added 5 c.c. of 
chloroform, then sufficient solution of sodium carbonate to impart an 
alkaline reaction, and the mixture at once shaken vigorously for two 
minutes. After having become perfectly clear, the chloroform extract 
is run into another separator (III.), and the aqueous, alkaline 
liquid again shaken three times successively with chloroform, using 
5 c.c. each time. To the combined chloroform extracts 20 c.c. of 
A710 hydrochloric acid are then added, and so much ether that the 
chloroform-ether mixture floats on the surface of the hydrochloric acid, 
after which the whole is shaken vigorously for two minutes. After 
having become perfectly clear, the acid liquid is filtered through a small 



LEAVES 241 

filter, previously moistened with water, into a colourless glass flask of 
about 2(X) c.c. capacity, the chloroform-ether mixture again shaken 
three times successively for two minutes with water, using lo c.c. each 
time, these liquids being passed through the same filter, which is 
subsequently washed with water, and the entire liquid finally diluted 
to about 100 c.c. 

After having added so much ether that the layer of the latter is 
about I cm. in depth, and lo drops of iodo-eosine solution, iV/ioo 
solution of potassium hydroxide is added to the liquid, the mixture 
being actively shaken after each addition, until the lower aqueous 
layer has assumed a pale red colour. For this purpose not more than 
9-6 c.c. of N/ioo potassium hydroxide should be required, so that at 
least 10-4 c.c. of N/ioo hydrochloric acid would be used up for the 
neutralisation of the alkaloid present. This would correspond to a 
minimumi of 0-3 per cent, of hyoscyamine in the leaves (i c.c. Njioo 
hydrochloric acid = 0-00289 g. hyoscyamine, using iodo-eosine as the 
indicator). 

The United States Pharmacopceia, in conformity with the above 
standards, requires that belladonna leaves should yield not less than 
0-3 per cent, of mydriatic alkaloids, when assayed by the official process. 

The amount of dry, aqueous extract yielded by belladonna leaves 
has been found to vary from 23-9 to 32-9 per cent. 

The German Pharmacopceia requires that powdered belladonna 
leaves should yield on ignition not more than 15 per cent, of ash. 

Coca. 

The dried leaves of Erythroxyluvi Coca, Lamarck. 

Determination of Cocaine (according to C. C. Keller). — To 12 g. of 
powdered coca leaves, contained in a flask of 150 c.c. capacity, are 
added 120 g. of ether, then after fifteen minutes 10 c.c. of a solution of 
ammonia (sp. gr, 0-960), and the whole frequently and vigorously 
shaken. After half an hour, 20 c.c. of water are added, and the separa- 
tion of the drug effected by prolonged, vigorous shaking. Subsequently 
100 g. of the dark green, ethereal solution (=10 g. of the leaves) are 
decanted, and allowed to stand for a short time, when a small amount 
of the finest particles of the drug, together with drops of water, will be 
deposited at the bottom of the flask. The clear solution is then trans- 
ferred to a separator, shaken first with 50 c.c. of 0-5 per cent, hydro- 
chloric acid, and then once again with 25 c.c. of the same dilute acid. 
The acid, aqueous liquid is placed in another separator, made alkaline 
with ammonia, and shaken twice successively with ether, using 40 c.c. 
each time. The clear, ethereal solution is then transferred to a tared 
flask, the ether distilled off, and the residue dried in a water-bath and 
weighed. 

Ill Q 



242 DRUGS AND GALENICAL PREPARATIONS 

The standard is about i per cent, of cocaine. 

Although the German Pharmacopoeia restricts the definition of 
Coca to the leaves of ErytJiroxylum Coca, which is the Bolivian or 
Huanuco variety, the British and United States Pharmacopoeias also 
recognise the Peruvian or Truxillo Coca, from E. Tnixillcnse, Rusby. 
The latter requires the dried leaves of either species to contain not less 
than 0-5 per cent, of the ethcr-solublc alkaloids of Coca, when assayed 
by the prescribed method.^ 

Digitalis. 

The dried leaves of flowering plants o{ Digitalis purpurea, Linne. 

Determination of Digitoxin (according to C. C. Keller). — 20 g. of the 
leaves are thoroughly extracted in a suitable apparatus, or by percola- 
tion, with 70 per cent, alcohol. The completeness of this operation may 
be controlled by allowing 3-4 c.c. of the last portions of the percolate to 
evaporate, taking up the residue with about 3 c.c. of water and two 
drops of hydrochloric acid, and testing the filtered liquid with a solution 
of tannin, when no appreciable turbidity should ensue. 

The entire percolate is evaporated in a porcelain dish on the 
water-bath, with active stirring, to about 25 g., in order to remove the 
alcohol, the residue then taken up with water, washed into a flask of 
250 c.c. capacity, and the total weight brought to 222 g. To this turbid 
solution of the extract are added 25 g. of a solution of basic acetate of 
lead, when a copious precipitate will be formed. By a gentle swaying 
of the flask a uniform mixture is obtained, but it should not be strongly 
shaken, otherwise much froth will be produced, which renders the 
subsequent filtration more difficult. The very voluminous precipitate, 
when washed and dried, weighs about 7 g., so that 12 g. of the 
liquid correspond to i g. of digitalis leaves. The thick mixture is 
brought on to a filter of about 18 cm. diameter, 132 g. of the filtrate 
collected, and to this clear, pale yellow liquid a solution of 5 g. of 
sodium sulphate in 7 g. of water is added, to precipitate the excess of 
lead. If the precipitation is conducted in an Erlenmeyer flask, which 
after some time is placed in a sharply inclined position, the lead 
sulphate will be deposited in such a manner that in the course of four or 
five hours 1 30 g. of the liquid ( = lo g. of digitalis leaves) can be decanted 
perfectly clear, and the difficulty of collecting and washing the precipi- 
tate on a filter is thus avoided. The liquid is then placed in a 
separator, and 2 c.c. of a solution of ammonia (10 per cent.) added, 
when it will become somewhat darker in colour, but must remain per- 
fectly clear, indicating that only traces of lead remain ; otherwise an 
emulsion will be formed by the subsequent extraction. It is then 

' For a comprehensive review of the methods of assay suggested for coca leaves, see Arch, 
Pharm., igio, 248, 303-336 ; /. Soc. Chem. Ind., 1910, 29, 897. 



LEAVES 243 

shaken four or five times successively with chloroform, using 30 c.c. each 
time. The united and only slightly turbid chloroform solutions are 
passed through a double, pleated filter of 8-9 cm. diameter, which has 
previously been moistened with chloroform, when the liquid will bi* 
obtained perfectly clear. It is then transferred to a tared Erlenmeyer 
flask, and the chloroform distilled off in a water-bath, when the digitoxin 
will remain as a yellow varnish. If the digitoxin is extracted from an 
acid instead of from an alkaline solution, it will be obtained in a much 
less pure form. 

The crude digitoxin contains small amounts of fat, and especially 
the odorous principles of the digitalis, and therefore requires purifica- 
tion. For this purpose the residue is dissolved in 3 g. of chloroform, 
and to the solution are added 7 g. of ether and 50 g. of light petroleum, 
when the digitoxin will be precipitated in white flakes, which are 
rapidly deposited, while the liquid, if actively shaken, will become 
perfectly clear. In order to obtain the precipitate in a suitable 
condition for weighing, a variety of methods may be adopted. 

The precipitate may be collected on a small, pleated filter, and the 
flask and filter washed vvith a little light petroleum, the small funnel 
being meanwhile kept covered with a watch-glass. After the light 
petroleum has passed through, the funnel is again placed in the neck 
of the flask, to the sides of which a portion of the digitoxin will have 
adhered, and the contents of the filter, while still moist, again brought 
into solution by pouring some hot absolute alcohol upon it. The 
alcoholic solution is evaporated, about 5 c.c. of ether added to the 
residue, and the ether then removed by heating in a water-bath, when 
the varnish-like digitoxin will be partially changed into the crystalline 
form. The residue is finally dried in a water-bath and weighed. 

Another method is as follows : — The flask with the precipitated 
digitoxin is placed in a sharply inclined position, and allowed to remain 
undisturbed for some hours, until the flakes have been well deposited, 
when the light petroleum is decanted, so far as this may be possible 
without loss. The remaining contents of the flask are weighed, and 
these evaporated at a gentle heat, which is best effected by blowing a 
warm current of air, by means of a hand-bellows, into the flask. Care 
should be taken not to place the flask in a hot-water bath, otherwise 
the contents will be thrown out with explosive violence. The digitoxin 
will remain as a white powder, which can now be weighed, but a 
correction of the weight is necessary. If it be assumed that the crude 
digitoxin weighed 0-062 g., the purified substance 0-048 g., the decanted 
light petroleum 50 g., and the contents of the flask which were 
evaporated 10 g., the latter would still have contained 0-0028 g. of 
impurities. The purified digitoxin would therefore be calculated as 
0-048 — 0-0028=0-0452 g. or 0-452 per cent. 



244 DRUGS AND GALENICAL PREPARATIONS 

Determination of Extract. — The yield of aqueous extract is deter- 
mined by the cold process, as described under Ergot (p. 225). 
The following values have been obtained : — 

Digitoxin .... 026 to 062 per cent. 

Dry, aqueous extract, up to . . 36 per cent. 

Menyanthes (Buckbean, Bogbean, Marsh Trefoil). 

The leaves oi Menyanthes trifoliata, Linne. 

Determination of Extract. — As described in the introduction to 
Leaves (p. 239), in the proportion of 10 to 200. 

Senna (Alexandrian). 

The dried leaflets of Cassia acutifolia, Delile. 

Determination of Extract. — In the same manner as with Menj'anthes. 

The German PharmacopcKia recognises only the Indian or 
Tinnevclly Senna, which consists of the dried leaflets of Cassia 
angnstifolia, Vahl, and requires that the powdered leaves should yield 
on ignition not more than 12 per cent, of ash. 

Strammonium. 

The leaves of Datiira Straminottium, Linne, collected at the time of 
flowering. 

Determination of Extract. — This is conducted as follows, according 
to the use of the leaves for the preparation of (i) tincture ; (2) oil ; or (3). 
extract. 

(i) By extraction with pure alcohol, as described in the introduc- 
tion to Flowers (III.) (p. 236). 

(2) By extraction with a mixture of 150 g. of 90 per cent, alcohol 
and 4 g. of a solution of ammonia (sp. gr. 0-960), in the same manner 
as the preceding. 

(3) By extraction with either cold or hot water. 10 g. of the sample 
are extracted with 100 g. of water ; the extraction with hot water is 
carried on for a quarter of an hour in a hot-water bath, the water lost 
by evaporation being made good. 

The United States Pharmacopoeia directs the assay of strammonium 
leaves for alkaloid to be conducted in the same manner as prescribed 
for belladonna leaves, and requires that they shall contain not less than 
0-25 per cent, of mydriatic alkaloids. 

The German Pharmacopoeia requires that powdered strammonium 
leaves should yield on ignition not more than 20 per cent, of ash. 

Uva Ursi. 

The dried leaves oi ArctostapJiylos Uva-Ursi i^xwwC), Sprengel. 



RHIZOMES 245 

Determinatioti of Extract. — By extraction with cold water, as 
indicated under Ergot (p. 225). 

By extraction with hot water, as described in the introduction to 
Leaves (p. 239), in the proportion of 10 : 200. 

By extraction with a mixture of equal parts by weight of 90 per 
cent, alcohol and water, as described in the introduction to Flowers 
(III.) (p. 236). 

VII. RHIZOMES. 

The rhizomes are examined in precisely the same manner as the 
roots, for which the details are given below (p. 247). The yield of 
either aqueous or alcoholic extract is determined as the directions for 
making the extract may require. The tests of the Pharmacopoeia are 
also to be considered. In the case of calamus rhizome the yield of 
alcoholic extract is determined. 

Galangal. 

The dried rhizome oi Alpmia offidnaruiii, Hance. 
Determination of Extract. — By extraction with 68 per cent, alcohol 
in the usual manner. 

Ginger. 

The dried rhizome of Zingiber officinale, Roscoe. 

Deterniinatiofi of Extract. — This is conducted either by extracting 
with a mixture of i part of 90 per cent, alcohol and 8 parts of water, 
or with 6?) or 90 per cent, alcohol. 

The German Pharmacopoeia requires that powdered ginger should 
yield on ignition not more than 7 per cent, of ash. 

Hydrastis (Golden Seal). 

The dried rhizome and roots of Hydrastis cattadettsis, Linne. 

(a) Deternmiation of Alcoholic Extract. — This is conducted according 
to the general method described under Roots (VIII.). The yield 
should be not less than 20 per cent. It has been found to vary from 
2004 to 28-0 per cent. 

(b) Determination of Hydrastine. — The following method is that of 
the German Pharmacopoeia: — To 6 g. of hydrastis rhizome in moderately 
fine powder, contained in a flask, are added 60 g. of ether, and, after 
vigorous shaking, 10 c.c. of a solution of ammonia (sp. gr. 0-960), the 
mixture being then allowed to stand for three hours, with frequent 
and vigorous shaking. When the liquid has become perfectly clear, 
40 g. of the ethereal solution (=4 g. of hydrastis rhizome) are 
filtered through a dry, well-covered filter into a flask, and the ether 
distilled off. The residue is then gently heated with 10 c.c. of 
dilute hydrochloric acid (i part of acid, sp. gr. M26, to 99 parts of 



246 DRUGS AND GALENICAL PREPARATIONS 

water), and the solution passed through a small filter, previously 
moistened with water, into a separator, the flask being washed twice 
successively with dilute hydrochloric acid of the above strength, using 
5 c.c. each time. These liquids are passed through the same filter into 
the separator, the filter being finally washed with a little water. To 
the united acid liquids are added 40 c.c. of ether, the mixture being 
vigorously shaken, and then sufficient solution of ammonia to impart 
an alkaline reaction, after which the mixture is at once shaken 
vigorously for two minutes. When it has become perfectly clear, the 
aqueous liquid is drawn off, the ethereal liquid remaining in the 
separator again shaken, and, when clear, 30 c.c. of it ( = 3 g. of hydrastis 
rhizome) are transferred to a light, tared flask. The ether is then 
allowed to evaporate at a moderate heat, and the residue dried at 100° 
until the weight remains constant. The amount of residue should be 
not less than 0-075 g-) corresponding to at least 2-5 per cent, of 
hydrastine, C.2iH._,^OyN. 

The same percentage of hydrastine is required by the United States 
rharmacopceia, when determined by the prescribed method of assay. 

Male Fern. 

The rhizome of Aspiduim Filix-mas (Linne), Swartz, collected in the 
autumn, divested of the roots, leaves, and dead portions, and carefully 
dried. 

The United States Pharmacopoeia, under the title of Aspidiuvi, 
recognises the dried rhizome of Dryopteris Filix-mas (Linne), Schott, 
or of D. via)-ginalis (Linne), Asa Gray. 

Dctcniiiiiation of Extract. — 10-20 g. of the rhizome, dried and in 
moderately fine powder, are extracted in a Soxhlet apparatus for one 
and a half to two hours with ether (sp. gr. 0720). The ether is then 
evaporated off in a tared flask, and the residue dried and weighed. 

Rhubarb. 

The dried rhizome of RJicuni palinatuiii, Linne, and R. officijialc^ 
Baillon. 

Determinatio7i of Extract. — Either the yield of aqueous extract is 
determined by the cold process, as described under Roots (VII L), or 
the extraction may be conducted with dilute alcohol according to the 
following method of the German Pharmacopoeia : — 

To 5 g. of rhubarb, in fine powder, are added 50 c.c. of a mixture 
of equal parts by weight of 90 per cent, alcohol and water, and the 
mixture allowed to stand for twenty-four hours, with frequent agitation ; 
20 c.c. of the clear, filtered liquid are then evaporated in a tared dish, 
and the residue dried at 105° until the weight is constant. The weight 



ROOTS 247 

should be not less than 07 g., corresponding to at least 35 per cent, of 
extract. 

The powdered rhubarb should yield on ignition not more than 12 
per cent, of ash. 

VIII. ROOTS. 

The directions, in general, are as follows, according to whether the 
yield of aqueous or alcoholic extract is to be determined : — 

(a) Aqueous Extract. — To 10 g. of the finely powdered root are 
added 100 g. of cold water, and the mixture allowed to stand for 
twenty-four hours, with frequent stirring ; the liquid is then passed 
through a dry filter, 20 c.c. of the filtrate ( = 2 g. of the root) evaporated 
in a tared dish, and the residue dried at 100° until of constant weight. 

(b) Alcoholic Extract. — The procedure is the same as in the case of 
the aqueous extract, but with the use of a mixture of equal parts of 
alcohol and water. 

Belladonna. 

The dried root of Atropa Bellado7ina, Linne. 

Determination of Alkaloid (according to C. C. Keller). — To 12 g. 
of dried belladonna root, in the form of powder, and contained in a 
flask, are added 90 g. of ether and 30 g. of chloroform, and the 
mixture allowed to stand for ten minutes, with frequent shaking. 
10 g. of a solution of ammonia (sp. gr. 0-960) are then added, and the 
maceration continued for half an hour, the mixture being repeatedly 
shaken. Subsequently 15 g. of water are added, the whole shaken 
vigorously for a few minutes, or until the powdered drug has agglomer- 
ated, and 100 g. of the clear liquid then decanted. This is shaken 
three times successively with i per cent, hydrochloric acid, the com- 
bined acid liquids made alkaline with ammonia, these extracted with 
a mixture of chloroform and ether, the ethereal liquid evaporated in 
a tared flask, and the residue weighed. The latter is subsequently 
dissolved in a little alcohol, the solution diluted with water, and 
titrated with N\\o hydrochloric or sulphuric acid with the use of 
haematoxylin as the indicator. i c.c. of iV/io acid = 00289 g. 
of atropine. 

The yield of alkaloid should be not less than 0-5 per cent. {cf. 
also the method of assay described under belladonna leaves, Section 
VI., p. 240). 

The following variations in yield have been found : — 

Aqueous extract . . . 20-0 to 23'33 per cent. 

Alkaloid .... 0-63 „ 070 „ 

The United States Pharmacopoeia requires that belladonna root 
should yield not less than 0-45 per cent, of mydriatic alkaloids, when 
assayed by the method prescribed for belladonna leaves. 



248 DRL'GS AND GALENICAL PREPARATIONS 

Gentian. 

The dried rhizome and roots of Gcntiana /utea, Linne, or of other 
species of Gctitiana, of which the German Pharmacopoeia specifies 
G. pa7inonica,^ZQ'^o\\\ G. purpurea, \S\x\Xik.; and G. punctata, \J\x\x\(t. 

Deten)ii7iation of Extract. — For the preparation of extract the root 
is treated as described for Frangula bark, under (L) (p. 235); for a 
Hquid extract it is extracted with a mixture of equal parts of alcohol 
and water ; and for a tincture with 68 per cent, alcohol. 

Ipecacuanha. 

The dried root of Uragoga ipecacuanha (Willdenow), Baillon. 

(a) Deterviination of Extract. — For the preparation of a liquid 
extract the root is extracted with 90 per cent, alcohol, for a tincture 
with 68 per cent, alcohol, and for the preparation of the syrup with a 
mixture of i part of alcohol and 8 parts of water, 

(b) Dctermijiation of Alkaloid. — The following method is that of 
the German Pharmacopoeia. To 12 g. of finely powdered ipecacuanha, 
contained in a flask, are added 90 g. of ether and 30 g, of chloroform, 
and, after vigorous shaking, 5 g. of a solution of sodium carbonate (i : 2) 
and 5 g. of water, the mixture being then allowed to stand for three 
hours, with frequent vigorous shaking. When it has become perfectly 
clear, 60 g. of the chloroform-ether mixture ( = 6 g. of ipecacuanha) are 
passed through a dry, well-covered filter into a flask, and the liquid 
distilled off. The residue is heated with 10 c.c, of dilute hydrochloric 
acid (i part of acid, sp. gr. 1-126, to 99 parts of water), the solution 
passed through a small filter, previously moistened with water, into 
a separator (I.), the extraction of the residue being then repeated 
with two successive portions of the same dilute acid as above, using 
5 c.c. each time, these liquids passed through the same filter, and the 
flask and filter finally washed well with water. To the united acid 
liquids are added 5 c.c. of chloroform, then a solution of sodium 
carbonate until the reaction is alkaline, and the mixture at once 
shaken vigorously for two minutes. When perfectly clear, the chloro- 
form solution is run into another separator (IL), and the extraction 
repeated three times in the same manner with chloroform, using 5 c.c. 
each time. To the united chloroform solutions are added 10 c.c. of 
A710 hydrochloric acid, and so much ether that the chloroform-ether 
mixture floats on the surface of the acid liquid, after which the whole 
is vigorously shaken for two minutes. When perfectly clear, the acid 
liquid is passed through a small filter, previously moistened with water, 
into a flask of 100 c.c. capacity, the chloroform-ether mixture then 
shaken three times successively for two minutes with water, using 
10 C.C. each time, these liquids also passed through the same filter, 



ROOTS 249 

which is finally washed with water, and the entire liquid diluted with 
water to lOO c.c. 50 c.c. of this solution ( = 3 g. of ipecacuanha) are 
transferred to a flask, about 50 c.c. of water added, together with a 
freshly prepared solution of a fragment of haematoxylin in i c.c. of 
alcohol, and so much Njio potassium hydroxide solution run into 
the liquid, with agitation, that the mixture assumes a deep yellow 
colour, which, by vigorous agitation, quickly passes into bluish-violet. 
For this purpose not more than 2-6 c.c. of Njio potassium hydroxide 
solution should be required, so that at least 24 c.c. of N/io hydrochloric 
acid are used up for neutralising the alkaloids present. This would 
correspond to a minimum of 1-99 per cent, of alkaloids (i c.c. Ayio 
hydrochloric acid =0-02482 g. of alkaloids, calculated as emetine, 
C30H44O4N2, with haematoxylin as the indicator). 

The amount of alkaloid has been found to vary from 0-97 to 
3-20 per cent. 

The United States Pharmacopoeia requires that ipecacuanha shall 
yield not less than 1-75 per cent, of alkaloids, when assayed according 
to the prescribed method. 

Liquorice (Russian). 

The dried root of Glycyrrhiza glandtilifera, Waldstein and Kitaibel. 

Determination of Extract. — If the liquorice is to be used for the 
preparation of an extract or syrup, the yield of extract is determined 
by the aid of heat in the following manner : — 

To 10 g. of finely cut or coarsely powdered liquorice root, contained 
in an enamelled vessel which is best weighed with a stirring rod, are 
added 300 g. of cold water, and the whole allowed to stand for an hour 
at the ordinary temperature, with frequent stirring. It is then slowly 
heated to boiling, with frequent stirring, and evaporated to about 
210 g. After standing overnight, the evaporated water is replaced, 
the mixture again stirred vigorously, and the whole brought upon a 
dry filter ; 20 c.c. of the clear filtrate (=1 g. of root) are then evaporated 
in a tared porcelain dish and the residue dried until of constant weight. 

The yield of extract by the cold process can be determined by 
extracting with a mixture of 99 g. of cold water and i g. of a solution 
of ammonia (sp. gr. 0-960) in a closed vessel. For the purpose of 
preparing an alcoholic extract or syrup, the root is extracted with 
100 c.c. of a mixture of 49 g. of 90 per cent, alcohol, 48 g. of water, and 
3 g. of solution of ammonia (sp. gr. 0-960). 

Rhatany. 

The dried root of Kravieria triandra, Ruiz and Pavon (Peruvian 
Rhatany), and of K. argentea, Martius (Para or Brazilian Rhatany). 



250 DRUGS AND GALENICAL PREPARATIONS 

In addition to these two sorts the United States Pharmacopoeia also 
recognises Savaniila Rhatan)', from K. Ixina, Linne. 

Dcterviiuation of Extract. — The yield of aqueous extract is 
determined by the cold process, as described under Ergot (p. 225). 

Senega. 

The dried rhizome and roots oi Polygala Senega, Linn(^. 

Dcteri)iinatio7i of Extract. — This is conducted as follows, according 
to the use of the roots for the preparation of (i) syrup ; (2) solid extract ; 
(3) liquid extract ; or (4) permanent extract (" Daucrextrakt," Dieterich). 

(i) B}' extraction with a mixture of i part of 90 per cent, alcohol 
and 3 parts of water. 

(2) By extraction with a mixture of 2 parts of 90 per cent, 
alcohol and 3 parts of water. 

(3) By extraction with a mixture of 2 parts of 90 per cent, 
alcohol and i part of water. 

(4) By extraction with either cold or hot water. The extraction 
with hot water is carried on for a quarter of an hour in a hot- 
water bath. 

Valerian. 
The dried rhizome and roots of Valeriana officinalis, Linne. 
Determination of Extract. — This is conducted in the usual manner 
with a mixture of equal parts of alcohol and water. 

IX. SEEDS. 

Kola Seeds. Kola Nuts. 

The seeds of Cola vera, Schumann, or of Cola acuminata, Schott 
and Endlichcr. 

The following methods of examination have been given by 
K. Dieterich: — 

(a) Determination of Total Alkaloid. — 10 g. of the finely rasped 
drug, which has been uniformly moistened with water, are mixed with 
10 g. of granular, unslaked lime, and the mixture placed in an extraction 
thimble. This is then extracted with chloroform in a Soxhlet apparatus 
for three-quarters of an hour, or only so long as the chloroform runs off 
clear, then washed with chloroform, and the solution evaporated in a 
dish to approximate dryness. The residue thus obtained is taken up 
with 20 c.c. of iV/i hydrochloric acid, by the aid of a very gentle heat, 
and the solution filtered into a separator of 100 c.c. capacity, the dish 
and filter being carefully washed, and the washings added to the acid 
liquid. The contents of the separator are made strongly alkaline with 
ammonia, allowed to stand for a quarter of an hour, with frequent 
shaking, and then extracted with three successive portions of chloroform, 
using 20 c.c. each time. The united chloroform solutions are finally 



SEEDS 251 

evaporated in an Erlenmeyer flask or in a crystallising basin, in the 
latter case placing the basin in a dish of hot water but not in a 
steam-bath, in order to prevent loss by the creeping of the liquid, and 
the caffeine, which is now quite white, dried until the weight is 
constant. The weight obtained, multiplied by lo, gives the percentage 
of total alkaloid. 

(b) Free aiid combined Alkaloid and Fat. — lo g. of the finely rasped, 
dry drug are mixed, without previously being moistened, with lo g. of 
coarse, purified sand, and extracted for two hours in a Soxhlet apparatus 
with chloroform. The resulting solution is evaporated, the residue 
dried until of constant weight, and the total weight of fat and free 
caffeine determined. This mixture is extracted with boiling water, the 
solution filtered, and the filter carefully washed. The aqueous solution 
is evaporated, and the crude caffeine, for the purpose of its purification, 
taken up with 20 c.c. oi N\\ h}'drochloric acid, as in the determination 
of total alkaloid. The acid solution is filtered, made alkaline with 
ammonia, and, after standing for a quarter of an hour, extracted three 
times successively with chloroform. The united chloroform liquids are 
then evaporated, and the residue dried until the weight is constant. 
This weight, multiplied by 10, gives the percentage of free caffeine. 
By subtracting the amount of the latter from that of the caffeine arid 
fat, as determined above, the amount of fat present is ascertained. The 
difference between the amount of free caffeine and that of the total 
alkaloid represents the combined caffeine. 

(c) Determination of Moisture. — 5 g. of the finely rasped drug are 
dried in a platinum dish at 100° until the weight is constant. 

(d) Determination of Ash. — The 5 g. of drug which had been used for 
the determination of moisture are ignited until, after cooling in a 
desiccator, the weight remains constant. 

(e) Test for Identity. — 20 g. of the drug are mixed with 10 g. of 
calcined magnesia, the mixture moistened with dilute alcohol, and then 
extracted with 100 g. of the latter by digestion at a gentle heat, which 
is best effected by allowing the mixture to stand in a warm room for 
twelve hours. The liquid is then expres.sed, filtered, and the filtrate 
transferred to a white glass vessel, the width of which is at least 10 cm. 
In a layer of this depth the liquid will show a bluish-green fluorescence, 
resembling that of curcuma tincture. This reaction is only given by 
unroasted kola powder. 

The following are the minimum and maximum values obtained : — 
Total Alkaloid . . . i-o to 2-0 per cent. 



Free Alkaloid . 

Combined Alkaloid 

Fat 

Moisture 

Ash 



o-io6 „ 0778 

0788 „ 1-282 

0324 „ 1-298 

9-49 ,, 13-57 

279 » 5-46 



252 DRUGS AND GALENICAL PREPARATIONS 

Requirements. — The extreme limits should be within the above 
figures, and the drug should contain the largest possible amount of 
alkaloid, but not less than i per cent., with a preponderating amount 
of combined alkaloid. 

It may be noted that, according to Gadamer, the caffeine is present 
in only a very loose form of combination, and that, both in the free and 
combined form, it is probably first produced in the process of dr}-ing. 
The much shorter method of examination of C. C. Keller or that of 
Siedler,^ with the use of ammoniacal chloroform, does not give so pure 
a caffeine, but suffices for a crude analysis. 

Black Mustard Seed. 

The ripe seed of Brassica tiigra (Linne), Koch. 

Detennination of the Essential Oil. — The following method is that 
of the German Pharmacopoeia : — To 5 g. of powdered mustard seed, 
contained in a flask, are added 100 c.c. of water at 20 -25^ The 
corked flask is then allowed to stand for two hours, with repeated 
agitation, 20 c.c. of alcohol and 2 c.c. of olive oil are added, and the 
mixture distilled with careful condensation. The first 40-50 c.c. 
which pass over are collected in a flask of 100 c.c. capacity which 
contains 10 c.c. of a solution of ammonia (sp. gr. 0-960), and 20 c.c. of 
Njio silver nitrate solution are added. A small funnel is then placed in 
the flask, and the mixture heated for an hour in a water-bath ; after 
cooling, it is diluted with water to 100 c.c. To 50 c.c. of the clear 
filtrate are added 6 c.c. of nitric acid and i c.c. of ferric ammonium 
sulphate solution (i part of ferric ammonium sulphate to be dissolved 
as required in a mixture of 8 parts of water and i part of dilute 
sulphuric acid of sp. gr. M09-M 14) ; not more than 6-5 c.c. of A710 
ammonium thiocyanate solution should then be required to produce a 
red coloration, which would correspond to at least 0-7 per cent, of all\l 
mustard oil (i c.c. of A710 silver nitrate solution = 0004956 g. of allyl 
mustard oil, with ferric ammonium sulphate as the indicator). 

i^.— GALENICAL PREPARATIONS. 
Since the manufacture of galenical preparations has become a 
branch of industry on a large scale, and is no longer restricted to the 
pharmacy, methods for their examination have been worked out. 
This has been rendered necessary by the fact that, as shown in the 
preceding Section, " Resins, Balsams, and Gum-Resins," the crude 
materials and drugs used for this purpose are not only subject to great 
variations, but also occur in commerce of such poor quality that the 
galenical preparations made from them must naturally be inferior 
in character. Although the methods for the examination of galenical 

1 Ber. d. deutsch. pharm. G(S., 1898, p. 18. 



GALENICAL PREPARATIONS 253 

preparations, such as tinctures and extracts, cannot be regarded as 
final, they, nevertheless, permit of forming an opinion which is to 
some extent useful respecting their quality and that of the drugs 
from which they were made. The methods employed depend 
upon the observation of such physical characters as transparency, 
colour, odour, taste, specific gravity, and, when practicable, the 
quantitative determination of some essential constituent. Such methods 
of examination have now been incorporated to a large extent in the 
German Pharmacopoeia, whereas the British and United States 
Pharmacopoeias do not as yet describe the physical characters of 
galenical preparations, and requirements respecting the control of 
quality or strength are restricted to those preparations of special 
potency whose active constituents permit of being quantitatively 
determined. 

The following data comprise some of the special methods of 
examination : — 

Papers. 

Test Papers. 

{A'ccordlng to E. Dieterick.) 

Sensitiveness. — Ten different strengths of dilute sulphuric acid are 
prepared, which should contain i part of SO3 in 1000, 5000, 10,000, 
20,000, 30,000, 40,000, 50,000, 60,000, 80,000, and 100,000 parts of 
water respectively, and also ten dilute solutions of ammonia which 
shall contain NH3 in the same proportions. The test papers prepared 
from filter paper are then examined for their sensitiveness by dipping 
a strip of the paper once in the solutions of sulphuric acid or ammonia, 
in the order of strength indicated above, and observing with which 
solution a change of colour takes place. 

The test papers prepared from writing paper are examined by 
placing on them a drop of the above solutions. 

The papers should respond to the following limits of sensitiveness : — 

Congo Red Paper . . i : 5000 to i : 10,000 SO3 

Curcuma Paper . . . i : 5000 „ i : 10,000 NH3 

Blue Litmus Paper . . i : 10,000 „ i : 40,000 SO3 

Red Litmus Paper . . I : 10,000 „ i : 30,000 NH3. 

Mustard Paper and Mustard Lint. 

{According to K. Dieterich and the German Pharmacopcsta.) 

(a) Amount of Mustard Flour. — This is determined by carefully 
scraping the mustard with a knife from 100 sq. cm. and weighing it. 

(b) Determination of Mustard Oil} — 100 sq. cm. of the mustard 

1 Cf, the determination of essential oil in black mustard seed, under Drugs. Also 
the determination of mustard oil in mustard flour, by C. Brioux, Ann. Cliim. analyi., 191 2, 17, 3 ; 
J. Soc. C/iem. Ind., 1912, 31, 148 ; and Greenish and Bartlett, Pharm.J., 1912, 88, 203. 



254 DRUGS AND GALENICAL PREPARATIONS 

paper, cut in strips, arc placed in a flask, and 50 c.c. of water at 20°-25"' 
added. The flask is then corked, allowed to stand for two hours with 
repeated agitation, 10 c.c. of alcohol and 2 c.c, of olive oil added, and 
the mixture distilled with careful condensation. The first 30 c.c. which 
pass over arc collected in a flask of 100 c.c. capacity which contains 
10 c.c. of a solution of ammonia (sp. gr. 0-960), and 10 c c. of A' 10 silver 
nitrate solution are added. A small funnel is then placed in the flask, and 
the mixture heated for an hour in the water-bath, when, after cooling, 
it is diluted with water to 100 c.c. To 50 c.c. of the clear filtrate are 
added 6 c.c. of nitric acid and i c c. of ferric ammonium sulphate 
solution; not more than 3-8 c.c. of A710 ammonium thiocyanate 
solution should then be required to produce a red coloration, which 
would correspond to at least 001 19 g. of allyl mustard oil in 100 sq. cm. 
(i c.c. of A710 silver nitrate solution = 0-004956 g. of allyl mustard oil, 
with ferric ammonium sulphate as the indicator). 

The mustard paper and mustard lint should conform to the 
following limits : — 

I. Coarse Flour. 

Coarse Mustard Flour to 100 sq. cm., 2-oi6-4-55i g. 
Mustard oil, calculated on the flour, 0-89- 1-57 per cent. 

I I. Fine Flour. 

Fine Mustard Flour to 100 sq. cm., 1-50-2-991 g. 
Mustard oil, calculated on the flour, 0-80-1-44 per cent. 

III. Mustard Lint. 

Mustard Flour to 100 sq. cm., 2-1-2-711 g. 

Mustard oil, calculated on the flour, i-ii-i-2i per cent. 

The British Pharmacopoeia directs that CJiarta Sitiapis (Mustard 
Plaster) should be prepared by spreading a mixture of 5 g. of equal 
parts of black and white mustard seed, deprived of fixed oil, with a 
sufficient quantity of solution of india-rubber, over about 2 sq. dm. of 
cartridge paper, whilst the United States Pharmacopoeia requires of 
Mustard Paper that a surface of 60 sq. cm. should contain about 4 g. of 
black mustard, deprived of fatty oil. 

Plasters. 

Plasters having a rubber basis, which* are now most largely used in 
medical practice, should be examined first of all for the amount of 
caoutchouc they contain. 

A method for the determination of caoutchouc has been worked out 
by K. Dieterich.^ 

' " Ueber die quantitative Bestimmung von Kautschuk in Kautschuk-Pflasterii," P/uirm. 
Zeit,^ 1903, No. 78, and the Helfenberger .AnnaUn^ KJ03. 



LIQUID OR FLUID EXTRACTS 255 

The general method for the examination of plasters consists in the 
determination of the water. This is effected by heating i g. of the 
respective plaster, contained in a tared, shallow, porcelain dish, in a 
drying oven at loo^, until the weight remains constant. 

The determination of glycerin, which is sometimes carried out, is 
very uncertain ; a reliable method is required before any conclusions 
can be drawn as to the amount of glycerin present. 

Liquid or Fluid Extracts. 

According to the general method of examination the following 
points are to be considered : — 

(a") Tests for Identity. — See the Helfenbei'ger Aimalen, 1891, pp. 50-80. 

(b) Specific Gravity at 15°. 

(c) Dry Residue at [00°. — 5 g. of the liquid extract are evaporated 
in a previously ignited and weighed platinum dish, and the residue 
dried at 100° until the weight is constant. 

(d) AsJi. — The dry residue is ignited. 

(e) Exaniinatio7t according to the Pharmacopoeia. — The number of 
liquid extracts adopted .by the national pharmacopoeias not only 
varies considerably, but in many cases there are also important 
differences with respect to their method of preparation, or in the 
nature of the solvent employed for the extraction of the drug. In 
accordance with these facts preparations bearing the same name 
may differ appreciably in character, and in the examination of such 
products consideration must therefore be taken of the requirements of 
the particular pharmacopoeia to which they are expected to conform. 
These differences are, moreover, by no means constant, since changes 
in the method of preparation or in strength are frequently made in 
successive revisions of a pharmacopoeia. The British Pharmacopoeia 
directs the following liquid extracts to be assayed for the proportion 
of their active constituents : — Belladonna root, cinchona, ipecacuanha, 
nux vomica, and opium. In the United States Pharmacopoeia 
such requirements are extended to the following fluid extracts: — 
Aconite, belladonna root, cinchona, coca, colchicum seed, conium, 
guarana, hydrastis, hyoscyamus, ipecacuanha, nux vomica, pilocarpus, 
scopola, and strammonium. 

A special method is given for the following unofficial preparation : — 

Liquid Extract of Kola. 

(From unroasted nuts, according to K. Dieterich.) 

(a) Determinatio?t of Total Alkaloid. — 20 g. of the liquid extract are 
evaporated to a syrupy consistency, or until all the alcohol has been 
removed, and the residue then treated as described under Kola Nuts 



256 DRUGS AND GALENICAL PREPARATIONS 

(Section IX., Seeds, p. 250). The weight of total alkaloid, multiplied by 
5, expresses the percentage. 

(b) Free and CoDibined Alkaloid. — 20 g. of the liquid extract are 
evaporated to a syrupy consistency, or until all the alcohol has been 
removed, and the residue treated as described under Kola Nuts (/;) 
(p. 251). By multiplying with 5 the percentage of free caffeine is 
obtained, and by subtracting the latter from the total alkaloid the 
percentage of combined caffeine is indicated. 

The purification of the caffeine can only be effected by means of 
acid, since many liquid extracts contain glycerin, from which the 
caffeine cannot be separated by either water or alcohol. 

(c) Ash 

(d) Specific Gravity \ According to the usual methods. 

(e) Residue, dried at 100 

(f) Identification. — The identification of liquid extract of kola may 
be effected either with the alkaloidal residue obtained, or with the 
extract itself. In the first case the identification depends upon the 
purple coloration which caffeine gives with chlorine water and 
ammonia (the so-called murexide reaction), or, if the extract be used, 
20 g. of the liquid are evaporated, the residue triturated with a solution 
of ammonia, and then shaken with ether. On evaporating the ethereal 
liquid, a residue will be obtained which, although impure, yields a purple 
colour with the above reagents. 

The figures obtained for the extract should be within the following 
limits, which will indicate that it has been prepared from the more active 
unroasted kola nuts : — 

Total Caffeine 

Free Caflfeine 

Combined Caffeine 

Dry Residue 

Ash ..... 

Specific Gravity at 15° 

Thick Extracts and Dry Extracts. 

In addition to the liquid or fluid extracts the German Pharmacopoeia 
recognises the following three forms of an extract : — 

I. T/iin Extracts, which have a degree of fluidity resembling that 
of fresh honey ; 2. Thick Extracts, which, when cold, do not permit of 
being poured ; and 3. Dry Extracts, which are such as can be powdered. 
In other pharmacopoeias their characters are designated as "soft," 
" firm," " in powder," of a " pilular consistence," etc. 

The general method for the examination of the above-mentioned 
extracts is, according to E. Dieterich, as follows : — 

(a) Reactions for Identity. 



0-95 to 


1-5 per cent 


O-IIO „ 


o-8io „ 


. 0-03 „ 


I-OI9 


. I4-0 „ 


I7-0 


I -04 „ 


1-42 „ 


. 0-974 „ 


0-976. 



TINCTURES. OINTMENTS 257 

(b) Loss on djyijig at ioo°. — 2 g. of the extract are dried at ioo° 
in an ignited and weighed platinum dish until the weight is constant. 

(c) Ash. — The dried extract is incinerated. 

(d) Examination according to the Pharmacopoeia. — The remarks con- 
cerning the variations in liquid or fluid extracts are equally applicable 
to the so-called solid extracts. Among those recognised by the British 
Pharmacopoeia the following are directed to be assayed for the pro- 
portion of active constituent : — Belladonna root, nux vomica, and opium. 
The United States Pharmacopoeia extends these requirements respect- 
ing strength to the following extracts : — Belladonna leaves, colchicum 
corm, hyoscyamus, nux vomica, opium, physostigma, scopola, and 
strammonium. 

Tinctures. 

The class of galenical preparations known as " Tinctures " exhibits 
not only great variation with respect to the number adopted by the 
different national pharmacopoeias, but also with regard to their mode 
of preparation and strength. No general standards can therefore be 
adopted for them, such as those of specific gravity and the amount of 
dry residue which they 5'ield on evaporation, and the more specific 
requirements must naturally be in conformity with those of the 
respective pharmacopoeias. The British Pharmacopoeia directs the 
tinctures of belladonna, nux vomica, and opium to be assayed for 
alkaloid, and the tincture of jalap is required to contain a definite 
amount of resin ; whereas the United States Pharmacopoeia extends 
these more precise requirements to the tinctures of aconite, belladonna, 
colchicum seed, hydrastis, hyoscyamus, nux vomica, opium, physostigma, 
and strammonium. 

Ointments. 

The British and United States Pharmacopoeias restrict their require- 
ments concerning ointments and cerates to the prescribed methods of 
preparation and strength. The only exception is the more precise 
requirements of the latter work for the following preparation : — 

Mercurial Ointment. 

The United States Pharmacopoeia directs that the amount of 
mercury contained in this preparation shall be determined by the 
following method:^ — Weigh lo g. of mercurial ointment in a tared dish, 
melt it, then remove it from the flame and add 50 c.c. of warm petroleum 
spirit. Stir the mixture well, allow the mercury to settle completely, 
and decant the petroleum spirit. Wash the residue with successive 
portions of 10 c.c. each of warm petroleum spirit until it is entirely free 

1 For the volumetric determination of mercury in miercurial preparations see Crewe, 
Pharm./., 1908, 81, 359 ; and Cowie, ibid., 1911, 87, 885. 

Ill R 



258 DRUGS AND GALENICAL PREPARATIONS 

from fatty matter, carefully retain all the separated mercury in the dish, 
and allow all traces of the petroleum spirit to evaporate. Add to the 
residue lo c.c. of dilute hydrochloric acid (lo per cent.), heat gently, 
and stir with a glass rod until the mercury collects in a globule. Pour 
off the acid, warm the mercury with a little distilled water, dry the 
globule on filter paper, and weigh. The mercury should weigh not less 
than 4-9 g. 

The corresponding preparation of the British Pharmacopcuia 
{^Ungiicntuvi Hydrargyri) contains about 48-5 per cent, of mercur}-, while 
that of the German Pharmacopoeia {Ungucntiini Hydrarg}'ri cincrcu))i) 
contains 30 per cent, of mercury. 



Literature. 

British Phannacopccia, 1898. 

British Pharmaceutical Codex, 191 1. 

Deutsches Arzneibuch, 5th edition, 1910. 

Dispensatory of the United States of America, latest edition. 

Greenish, H. G. — Materia Medica, 1909. 

Greenish, H. G. — The Microscopical Examination of Foods and Drugs, 19 10. 

The National Standard Dispensatory, latest edition. 

United States Pharmacopceia, 8th revision, 1900, published 1905. 



ESSENTIAL OILS 

By E. GiLDEMElSTER, Ph.D., Leipzig. English translation revised by 
Frederick B. Power, Ph.D., LL.D., Director of the Wellcome Chemical 
Research Laboratories, London. 

The 'examination of essential oils for the purpose of detecting 
adulterations is conducted partly by physical and partly by chemical 
methods. 

In the first place, by determining the physical properties it is 
ascertained whether the oil under examination is a normal one. That 
is the case if all the constants are within the limits adopted for pure 
oils. The chemical examination, as a rule, affords information regarding 
the quality of the oil, and_ by this means the nature and amount of any 
adulterant present may also be found. 

The physical tests comprise the determination of the specific gravity, 
optical rotatory power, and solubility in alcohol of different strengths, 
sometimes also the congealing point, boiling point, and amount of 
residue left on evaporation. The usual adulterants, such as alcohol, 
fatty oil, petroleum, oil of turpentine, cedar-wood oil, etc., almost always 
affect one or more of the physical constants, and may thus be detected. 
For example, oil of turpentine when added to oil of sweet orange 
diminishes its rotatory power, while the presence of cedar-wood oil in 
oil of lavender renders the latter insoluble in 70 per cent, alcohol. The 
adulteration of any essential oil with alcohol causes a decrease in 
specific gravity, while the addition of petroleum to the oil of star-anise 
lowers its congealing point and influences its solubility in 90 per cent, 
alcohol. 

The chemical examination of an essential oil is closely connected with 
its physical tests. If a definite adulteration is suspected, an attempt should 
be made to isolate the adulterant and to identify it. Even when an oil 
has been found to be normal, a determination of its quality is frequently 
desirable, but among the methods subsequently to be described the one 
to be employed would depend upon the composition of the respective 
oil. The chief constituents of some oils, and those which determine its 
value, are alcohols, while in other cases they are esters, aldehydes, 
phenols or ketones, and by their quantitative determination information 
is not only obtained with regard to the normal or abnormal character 
of the oil, but also respecting its quality. Thus, of two unadulterated 

259 



260 ESSENTIAL OILS 

lavender oils, that would be considered the better which contains the 
larger percentage of esters. Cassia oil is valued according to its con- 
tent of cinnamic aldehyde, caraway oil according to the amount of 
ketone it contains, and clove oil according to the amount of its 
phenolic constituent. 

Determination of the Physical Constants. 

Specific Gravity. — When a sufficient quantity of material is avail- 
able, the specific gravity is most conveniently determined by means of 
the hydrostatic balance of Mohr or Westphal. If the amount of oil is 
not sufficient for this method, a pyknometer may be used, the tempera- 
ture being maintained at 15". 

Optical Rotatory Power. — The rotatory power of essential oils can 
be determined in an)- polarising apparatus which is adapted for sodium 
light ; the half-shadow apparatus of Laurent is especially to be recom- 
mended. In the case of dark oils, short observation tubes having a 
length of 50 and 20 mm. may be used, in order to avoid dilution with a 
solvent. The angle of rotation, which is directly observed in a 100 
mm. tube, is designated as «, and the specific rotatory power ^ as [a]i„ 

which is calculated according to the formula [a]^ = _ii- In this 

formula / denotes the length of the tube in millimetres, and d the 
specific gravity of the liquid. In general, it is not necessary to maintain 
a definite temperature, but with some oils, such as those of lemon and 
sweet orange, the determination is conducted at 20°. 

Solubility. — For the customary determination of the solubility of 
essential oils, alcohol of 70, 80, and 90 per cent, by volume is chiefly 
employed. To i c.c. of the oil, in a small graduated cylinder, alcohol of 
a definite strength is added, drop by drop, until solution is effected. In 
most cases the liquid will remain clear when further amounts of the 
solvent are added, but sometimes an opalescent turbidity will subse- 
quently appear, even with pure oils. If the oil under examination 
contains petroleum, this will separate on the surface of the liquid in 
drops after standing for a time, whereas fatty oil will collect at the 
bottom of the vessel. Cedar-wood oil, copaiba oil, and gurjun oil, as 
well as oil of turpentine, are quite sparingly soluble in alcohol, and are 
indicated by this property when they have been added with a fraudulent 
purpose to other more readily soluble oils. 

Congealing Point. — The apparatus employed in the laboratory of 
Schimmel & Co.- for determining the congealing point of essential oils, 

' Cf. H. Landolt, Das optische Dre/iungsvermogen organischer Substanzeit, 2nd Edition, 1898. 
English translation by J. H. Long, The Optical Rotating Power 0/ Organic Substances and its 
Practical Applications, 1902. 

'^ Semi-annual Report of Schimmel & Co., October i8y8, p. 43. 



PHYSICAL CONSTANTS 



261 



such as those of anise, star-anise, and fennel, is adapted from tlie well- 
known apparatus of Beckmann for determining molecular weights by 
the depression of the freezing point, and has the form represented 
in Fig. 46. 

The battery jar A serves as a receptacle for the cooling liquid or 
freezing mixture. The glass tube B suspended from the metal cover 
forms an air-jacket around the freezing tube C, and prevents the pre- 
mature solidification of the oil to be tested. The freezing tube C is 
wider at the top, and becomes narrower at the place where it rests on 
the rim of the tube B. In order to retain C in a fixed position, three 
glass supports are fastened on the inside of the 
tube B, about 5 cm. below its upper edge. The 
thermometer, which is graduated in h degrees, 
is securely held by three springs in a metal disc, 
which permit of sliding it up or down. 

To carry out a determination with anise or 
star-anise oil the battery jar is filled with cold 
water and pieces of ice, but for fennel oil a 
freezing mixture prepared from ice and salt is 
used. So much of the oil to be examined is 
then brought into the freezing tube as to have 
a height of about 5 cm., and the thermometer is 
immersed in the liquid without allowing it to 
touch the sides of the glass at any point. 
During the process of cooling, the super-cooled 
oil is protected from any disturbance which 
would cause its premature solidification. If the 
temperature has sunk to about 5° below the 
congealing point, that is, with anise oil to 12°^ 
with star-anise oil to 10°, and with fennel oil 
to 3°, crystallisation is induced by rubbing or 
scratching the sides of the glass with the ther- 
mometer. If this procedure is not successful, a 
small crystal of the congealed oil or a little solid anethol is brought 
into the liquid, when solidification will ensue with a considerable 
development of heat. The solidification may be accelerated by con- 
stant stirring with the thermometer, when the temperature will rise 
rapidly, and finally attain a maximum, which is termed the "congealing 
point " of the oil. 

If such an apparatus as the above is not available, the determination 
can be conducted in an ordinary flask, which is cooled by placing it in 
a freezing mixture, provided the amount of oil is not too small, that 
is, not less than 100 g. 

Fractional Distillation. — Fractional distillation is employed when it 




Fio. 46. 



2G2 



ESSENTIAL OILS 



is a question of isolating a definite constituent of an oil or of separating 
individual portions from each other. For a scientific examination it 
is necessary to subject the oil to repeated fractional distillation, with 
the aid of a fractionating column, in order to separate the constituents 
of different boiling point, and even then the separation is sometimes 

Lvery incomplete. In testing for 
adulterants, fractional distillation 
will frequently effect the isolation 
of the adulterating agent, such as 
alcohol, petroleum, oil of turpentine, 
and other liquids. Lemon oil, rose- 
mary oil, and oil of spike are tested 
for turpentine oil b}' distilling over 
lo or 50 per cent, of the respective 
oil, and determining the rotatory 
power of the distillate. In order 
to obtain concordant results by this 
method, distillation flasks of uniform 
size must be used, and the fractiona- 
tion so conducted that the distillate 
passes over drop by drop. 

The Ladenburg fractionating 
flask, which is used in the labora- 
tory of Schimmel & Co.^ for testing 
the three above-mentioned oils, has 
the shape and size indicated in Fig. 47. 

The statements regarding boiling point in this Section refer to 
determinations in which the mercurial column of the thermometer 
is entirely in the vapour of the liquid. 




Fio. 47. 



Chemical Methods of Examination. 

Determination of the amount of Esters by Saponification. 

The esters of the alcohols C^^IIiviO and CjyHooO, on account of 
their pleasant odour, represent some of the most valuable constituents 
of essential oils. Linalyl acetate is the chief odorous component 
of the oils of bergamot, petit-grain, and lavender ; bornyl acetate 
imparts to the pine-needle oils their characteristic aroma; menthyl 
acetate occurs in peppermint oil, and other examples might be given. 
All these esters are readily saponified by an alcoholic solution of 
potassium hydroxide, and may thus be determined quantitatively, 
in fact, in the same manner as is customary in the analssis of fats. 

These methods of examination include the determination of the acid 



^ Semi-annual Report of Schimmel & Co., October 1898, p. 41. 



CHEMICAL EXAMINATION 263 

value (A. v.), ester value (E.V.), and saponification value (S.V.). The 
acid value expresses how many milligrams of potassium hydroxide 
are necessary for neutralising the free acid contained in i g. of oil. 
The ester value denotes the number of milligrams of potassium 
hydroxide required to saponify the esters contained in i g. of oil. 
The saponification value designates the sum of the acid and ester 
values. Since the essential oils usually contain but very little free acid, 
this determination can generally be neglected. 

The saponification is conducted in a small, wide-necked flask of 
potash glass, having a capacity of loo cc. A glass tube, about i m. in 
length, which is inserted in a perforated stopper, will serve as a reflux 
condenser. In such a flask about 2 g. of the oil are weighed accurately 
to I eg. and 10-20 cc. of A72 alcoholic solution of potassium hydroxide 
added ; in most cases 10 cc. of NJ2 potassium hydroxide solution are 
sufficient, but with some oils having a high ester content, such as 
Roman chamomile and wintergreen oils, 30 cc must be used. The 
oil should, however, first be tested for free acid, after the addition of a 
little alcoholic solution of phenolphthalein. The flask, with the 
attached condenser, is then heated on a steam-bath for half an hour to 
one hour, after which th'e cooled contents of the flask are diluted with 
about 50 cc of water, and the excess of alkali titrated with 7V/2 
sulphuric acid. In order to saponify menthyl and bornyl w^^valerates 
completely, they must be boiled for two to three hours with a consider- 
able excess of alkali. 

In order to calculate from the saponification value found the amount 
of linalyl, geranyl, or bornyl acetate (QoHi^O.COCHg.molec wt.= 196) 
contained in an oil, the following equation is employed : — 

196XS.V. , r , 

— — = percentage 01 ester. 

In the case of acetic esters of alcohols such as menthol, citronellol, 

etc. (C^oHjgO. COCH3. molec wt. = 198), the percentage of esters is 

, , ,, ^. 198 X S.V. 
expressed by the equation : -^ — . 

In order to ascertain the amount of alcohols of the formulae 
C10H13O (molec wt. = 154), C10H20O (molec wt. = 156), and C^gHg^O 
(molec wt. = 220) respectively, the following equations are used : — 

1 54 X S.V. 1 56 X S.V. , 220 X S.V. 

^ ) — — ^ , and 2 . 

560 560 560 

Determination of the amount of free Alcohols by Acetylation. 

The alcohols of the formulae CjoHigO, CjoHgoO, and CigH.^^O 
respectively, which occur as esters in essential oils, are also frequently met 
with in the free state ; for example, borneol, geraniol, terpineol, linalool, 



264 



ESSENTIAL OILS 



thujyl alcohol, menthol, citronellol, and santalol. For their quantitative 
determination advantage is taken of their property of becoming converted 
into acetic esters by heating with acetic anhydride, in accordance with 
the equation : — 

CioHisO + (CH3CO),0 = CioHi,O.COCH3+CH3CO,H. 

This change only takes place quantitatively in the case of borneol, 
geraniol, menthol, citronellol, and santalol. Linalool 
and terpineol, on the other hand, become partially 
decomposed on heating with acetic anhydride, with 
the elimination of water. For the purpose of a 
quantitative acetylation,' lo c.c. of the oil, together 
with an equal volume of acetic anhydride and about 
2 g. of anhydrous sodium acetate, are brought into a 
small flask provided with a ground-glass condensing 
tube (Fig. 48), and the mixture maintained in a uniform 
state of ebullition for one hour. After cooling, some 
water is added to the contents of the flask, which is 
then heated for a quarter of an hour on a water-bath 
in order to decompose the excess of acetic anhydride. 
By means of a separating funnel, the aqueous, acid liquid 
is subsequently drawn off from the oil, and the latter 
washed with water, or preferably with a solution of 
common salt, until the washings are neutral. 

After having been dried with anhydrous sodium 
sulphate, 2 g. of the acetylated oil are saponified according to the 
method described above (p. 263). From the ester value thus found, 
the corresponding amount of the alcohol contained in the original 
oil is calculated, according to the following equations : — 

«x 15-4 




Fio. 48. 



1. Percentage of alcohol CjoH^gO in the original oil = 

2. Percentage of alcohol Ci^HgoO in the original oil = 

3. Percentage of alcohol C^jHo^O in the original oil 



i- — (rt:x 0-042) 
axiS -6 

s — {ax 0-042) 
ax 220 



s — {ax 0042) 

In these formulae a designates the number of c.c. of N/i potassium 
.hydroxide solution used, and s the amount of acetylated oil employed 
for saponification, expressed in grams. 

Aldehyde Determination by the Bisulphite Method 
of Schimmel & Co. 

This method depends upon the property of some aldehydes of 
forming compounds with sodium bisulphite which are soluble in water. 

' Semi-annual Report of Schimmel & Co., October 1894, p. 62. 



CHEMICAL EXAMINATION 



265 



If oils rich in aldehyde, such as cassia oil, Ceylon cinnamon oil 
(cinnamic aldehyde), or lemon-grass oil (citral) be shaken with a hot, 
concentrated solution of sodium bisulphite, the total aldehyde will pass 
into the aqueous solution, whilst the other constituents of the oil, 
being insoluble in water, will float on the surface. The diminution in 
volume of the oil by this process corresponds to its content of aldehyde. 

For such a determination a special glass flask ^ (cassia flask or 
aldehyde flask. Fig. 49) of about 100 c.c. capacity is used. This has 
a neck about 13 cm. in length, 8 mm. inside diameter, 
and is graduated in —^ c.c. The neck has a capacity of 
somewhat more than 6 c.c, and the zero of the scale 
is a little above the junction of the body of the flask 
and the neck. 

By means of a pipette, exactly 10 c.c. of oil are 
brought into the flask, the same amount of an approxi- 
mately 30 per cent solution of sodium bisulphite added, 
the mixture shaken, and the flask then placed in a bath 
of boiling water. After the curdy mass which is first 
formed has liquefied, so much bisulphite solution is 
gradually added, while being constantly heated in the 
water-bath and frequently shaken, that the flask be- 
comes at least three-quarters filled. The heating is 
then continued for some time, or until no more solid 
particles float in the liquid, and there is a layer of 
clear oil on the surface of the salt solution, while the 
odour of the aldehyde has disappeared. After cooling, 
the flask is filled with bisulphite solution, so that the 
oil rises in the neck, and the lower boundary of the oily 
layer is exactly in line with the zero mark on the neck 
of the flask. The number of cubic centimetres of non-aldehydic con- 
stituents is then read off on the scale, and by subtracting this from 
10 the aldehyde content is found. 

This method can only be somewhat accurately employed for oils 
which are relatively rich in aldehyde, such as cassia oil, cinnamon oil, 
and lemon-grass oil. It is quite inadequate for lemon oil, which 
contains but small amounts (5-8 per cent.) of aldehyde. 




Fio. 49. 



Determination of Aldehydes and Ketones with Neutral Sulphite, 

according to Burgess (The Sulphite Method). 

In place of the acid sulphite, neutral sodium sulphite may also be 
used in the cassia flask for the quantitative determination of citral 
and cinnamic aldehyde. Even the ketones, carvone and pulegone, may 

1 Semi-annual Report of Schimmel & Co., October 1890, p. 18. 



266 ESSENTIAL OILS 

be determined in the same manner, which is not possible by the method 
above described. 

The determination is conducted in the following manner: — 5 c.c. of 
the oil are brought into a cassia flask, together with a saturated 
solution of sodium sulphite, and, after the addition of two drops of a 
phenolphthalein solution, the mixture is heated in a water-bath, with 
frequent agitation. The sodium hydroxide which is liberated by this 
reaction is neutralised from time to time with dilute acetic acid (i : 5) 
or with sodium bicarbonate, until a red coloration no longer appears 
on further heating. The oil then is brought into the neck by filling the 
flask with water, and, after cooling, its volume may be accurately 
determined. The amount of oil absorbed, multiplied by 20, gives 
the percentage content of aldehyde or ketone. 

S. Sadtler^ has proposed to determine volumetrically the sodium 
hydroxide liberated by the action of aldehydes or ketones, with the 
use of rosolic acid as the indicator, and thus to calculate the amount 
of aldehyde or ketone in the oil. This method, however, fails in 
practice, owing to the impossibility of determining the end reaction 
with precision. 

Determination of Phenols. 

For an approximately accurate determination, a measured quantity 
of the oil to be examined is shaken with a dilute (not more than 
5 per cent.) solution of sodium hydroxide. The diminution in volume 
of the oil indicates the amount of phenols present. For this purpose 
a burette of 60 c.c. capacity is filled to the 10 c.c. mark with a 5 per 
cent, solution of sodium hydroxide. 10 c.c. of the oil to be examined 
are then brought upon the surface of the liquid, the burette closed with 
a tightly fitting cork, and, after shaking the mixture vigorously, allowed 
to stand for twelve to twenty-four hours. Any drops of oil which may 
adhere to the sides of the glass are detached by tapping or inclining 
the burette. When the alkaline liquid has become clear, the amount 
of non-phenolic constituents of the oil can be read off. 

The cassia flask described on p. 265 can also be used for phenol 
determinations in place of a burette. 

Detection of Alcohol. 

The adulteration of an essential oil with alcohol, which is of frequent 
occurrence, is indicated in the first place by a low specific gravity. 

When drops of an oil containing alcohol are allowed to fall into 
water, they will not remain clear and transparent as in the case of a 
pure oil, but will appear opaque or show a milk-like turbidity. 

In order to separate and identify the alcohol, the suspected oil is 

' J. Soc. Chetn. frui., igo^, 23, 303. 



CHEMICAL EXAMINATION 267 

heated until it begins to boil, the first few drops of the distillate 
collected in a test tube, and then passed through a filter which has 
been moistened with water, so as to remove any drops of oil which may 
have been mechanically carried over. After the filtered liquid has 
been made strongly alkaline with a dilute solution of potassium 
hydroxide, and heated to 50°-6o'', a solution of iodine in potassium 
iodide is added until a permanent yellow coloration is produced. If 
alcohol be present, small crystals of iodoform will be deposited after a 
time at the bottom of the liquid. It is, however, to be borne in mind 
that acetone and ethyl acetate, as well as the lower aldehydes, will give 
the iodoform reaction under the same conditions. 

If a measured quantity of an oil containing alcohol be shaken in a 
graduated cylinder with water, the increase in volume of the aqueous 
layer will correspond approximately to the amount of alcohol present. 
The alcohol can then be separated from the water by distillation, and 
identified as described above. 

The amount of alcohol in an adulterated oil may also be determined 
by a comparison of the specific gravity of the oil before and after 
shaking with water. 

Detection of Fatty Oil. 

If an essential oil is adulterated with a fatty oil, it does not yield 
a clear solution with considerable amounts of 90 per cent, alcohol, and 
leaves a permanent greasy stain when evaporated on writing paper. It 
is to be borne in mind, however, that the essential oils obtained by 
expression, such as those of bergamot, lemon, and sweet orange, produce 
similar permanent stains on paper; but these oils are soluble in 90 per 
cent, alcohol, and the stain is not caused by fatty oil. For the detection 
of the fatty oil, the essential oil is either distilled over with steam, or 
evaporated on a water-bath. The residue, when it consists of fat, will 
be insoluble in 70 and 90 per cent, alcohol (only ricinus oil is soluble 
in 90 per cent, alcohol, but it is insoluble in 70 per cent, alcohol) ; it 
will give off the irritating vapours of acrolein when heated in a test 
tube with acid potassium sulphate, and will be saponified by an 
alcoholic solution of potassium hydroxide, giving a saponification value 
between 1 80 and 200. 

Detection of Mineral Oil. 

Petroleum, mineral oil, or fractions of the latter, are practically 
insoluble in alcohol, even of the highest strength, and they are, there- 
fore, easily detected in essential oils. An essential oil which is 
adulterated with a mineral oil will yield a turbid mixture when shaken 
with 90 per cent, alcohol, but this will soon become clear on standing, 
and the separated mineral oil will then float on the surface of the 
alcohol. The mineral oil, when repeatedly washed with alcohol, will be 



268 ESSENTIAL OILS 

recognised as such by its permanence towards a solution of potassium 
hydroxide, as also towards concentrated sulphuric and nitric acids. 

Detection of Turpentine Oil. 

The most frequentl)- observed adulteration of essential oils consists 
in an addition of turpentine oil. Those oils which in a pure state 
contain no pinene — the chief constituent of oil of turpentine — may be 
examined for an adulteration with the latter by repeated fractional 
distillation and the isolation of the respective hydrocarbon. The 
portion distilling at about i6o° is separately collected, and the pinene 
identified by its characteristic derivatives, for which purpose the 
nitrosochloride and the bases prepared therefrom, pinene nitrolbenzyl- 
amine or pinene nitrolpiperidine, are best adapted. 

According to the directions given by O. Wallach,^ 50 g. each of the 
respective fraction, glacial acetic acid, and ethyl nitrite (or amyl nitrite) 
are well cooled in a freezing mixture, and to the mixture of the three 
substances 15 c.c. of crude (33 per cent.) hydrochloric acid are gradually 
introduced. The nitrosochloride soon separates in a crystalline form, 
and when drained at the pump and washed with cold alcohol is obtained 
sufficiently pure for further treatment. A portion of the nitrosochloride 
is hydrolysed with a solution of potassium hydroxide and converted 
into nitrosopinene,- melting at 132°. To another portion an excess of 
an alcoholic solution of benzylamine or piperidine is added,^ the mixture 
heated for a short time on the water-bath, and the nitrolamine thus 
produced separated by the addition of water. The melting point of 
pinene nitrolpiperidine is i i8°-i 19°, that of pinene nitrolbenzylamine, 

I22°-I23°. 

In those cases in which pinene is a natural constituent of an 
essential oil, an adulteration with turpentine oil may be recognised by 
a change in its physical constants, such as specific gravity, solubility, 
and rotatory power. With regard to the optical behaviour, it should 
be noted that there are both dextrorotatory and laevorotatory turpentine 
oils. 

Constants and Properties of some Essential Oils of 
Commercial and Industrial Importance.^ 

Anise Oil. — From the fruits oi Piiiipinella Anisuui, Linnc. 
d"^" 0-980-0-990 ; a^ laevorotatory to — i" 50' (an oil to which fennel 
oil or fennel stearoptene has been added is dextrorotatory); soluble in 

' Annalen, 1888, 245, 251, and 1889, 253, 251. - Wallach and Lorentz, ibid., 1891, 258, 198. 

3 Wallach, ifiid., 1888, 245, 253 ; 1889, 252, I 30. 

* Since it is not expedient to enumerate ail the essential oils, reference may be made to the 
comprehensive work : Die (vtherischen Oe/e, by E. Gilderaeister and P'r. Hoffmann. This 
contains more detailed information respecting their origin, preparation, composition, and 
commercial varieties. 



CONSTANTS AND PROPERTIES 269 

ii-3 vols, of 90 per cent, (by volume) alcohol; congealing point 
(see p. 260) + 17" to + 19^ When improperly kept the congealing point 
may become depressed to below 0°, and at the same time the oil will 
become heavier than water through the formation of anisaldehyde. 

Anet/iole, C^^V[^S^.—d''^° 0-984-0-986 ; an ± 0° ; ;/d^^° i-SSQ-I'S^i ; 
congealing point 2i°-22°; melting point 22-5°-23° ; boiling point (760 
mm.) 233°-234° ; soluble in 2-3 vols, of 90 per cent, alcohol. 

Bay Oil. — From the leaves oi Pimenta acris, Wight. 

d'^'"'' 0-965-0-985 ; a^ laevorotatory to —3°. Usually not giving a 
clear solution with 90 per cent, alcohol. Eugenol content 40-70 per 
cent. The determination of the eugenol is conducted in the manner 
described under Clove Oil. 

Bergamot Oil. — The oil expressed from the rind of the fruit of 
Citrus Bergaiiiia^ Risso. 

Colour green or yellowish-brown ; (^'^^ o- 881-0-886 ; ar, -f 8" to + 24° ; 
soluble in \ vol. or more of 90 per cent, alcohol. Amount of 
linalyl acetate (see p. 262) 35-45 per cent; residue on evaporation, 
5-6 per cent. For determining the latter, about 5 g. of the oil are 
weighed accurately to i eg. in a tared glass dish, and heated on a 
water-bath until the residue has completely lost the odour of bergamot 
oil. After cooling, the dish is weighed with the residue. This will 
amount to more than 6 per cent, of the oil if fatty oil were present. 
Rectified bergamot oil is colourless, and volatilises without leaving 
any appreciable residue. 

Bitter Almond Oil. — Prepared by the fermentation and subsequent 
distillation of bitter almonds, from Prunus Amygdalus, Stokes, or of 
apricot kernels, from Prunus Armeniaca, Linne, which have been 
deprived of fatty oil. 

Bitter Almond Oil containing Hydrocyanic Acid. — d^^'^ 1-045-1 -070, 
but with a large proportion of hydrocyanic acid the specific gravity is 
higher; a^ inactive or nearly so; soluble in 1-2 vols, of 70 per cent, 
alcohol. 

Bitter Almond Oil deprived of Hydrocyanic Acid. — d^^" 1-050- 1-05 5 ; 
boiling point 179". In order to distinguish this oil from one containing 
hydrocyanic acid, 10-15 drops of the respective oil are shaken with 
2-3 drops of an approximately 30 per cent, solution of sodium hydroxide, 
or a corresponding amount of more dilute alkali. After the addition of 
a few drops of a partially oxidised ferrous sulphate solution, the mixture 
is again shaken, and then acidified with dilute hydrochloric acid, when 
the precipitate of ferroso- ferric oxide will be dissolved, and, if hydro- 
cyanic acid be present, the characteristic blue precipitate of prussian 
blue will be formed. 

For the quantitative determination of hydrocyanic acid in essential 
oils various volumetric methods have been proposed, some of which. 



270 ESSENTIAL OILS 

however, give very poor results. The following gravimetric method has 
been found most trustworthy : — About i g. of the oil is accurately weighed, 
dissolved in ten to twenty times its amount of alcohol, and lo g. of a 
chlorine-free, alcoholic solution of ammonia added. After standing for 
a time, an aqueous solution of i g. of silver nitrate is added, and the 
mixture then acidified with nitric acid. When the liquid has become 
clear, the silver cyanide is collected on a dried and weighed filter, 
thoroughly washed w^ith water, and dried at lOo' until the weight is 

constant. 

The silver precipitate thus obtained contains the entire amount of 
hydrocyanic acid present in the oil, whereas without the preceding 
treatment with ammonia, w^hich decomposes the mandelic nitrile, only 
a part of the hydrocyanic acid would be determined. 

Detection of Chlorine. — Synthetic bitter almond oil prepared from 
benzyl chloride or benzylidene chloride, is more or less contaminated 
with chlorinated products. Since synthetic benzaldehyde is much used 
to adulterate true bitter almond oil, its presence can be ascertained by 
the detection of chlorine. Synthetic cinnamic aldehyde likewise some- 
times contains chlorine, and the detection of chlorine in cinnamon oil 
is similarly evidence of its adulteration with the synthetic aldehyde. 
It should specially be noted, however, that synthetic benzaldehyde and 
cinnamic aldehyde which are free from chlorine now also occur in 
commerce. 

For the detection of chlorine a piece of filter paper 5x6 cm. in size 
is folded in the form of a taper, soaked in the oil to be examined, and _ 
the excess of oil thrown off by two short shakings with the hand. The 
paper thus prepared is brought into a small porcelain dish, which is 
placed in a larger one of about 20 cm. diameter, and lighted by a flame. 
A beaker of about 2 litres capacity, which has been moistened on the 
inner surface with distilled water and kept ready for the purpose, is then 
quickly inverted over the burning taper. The gaseous products of 
combustion condense on the moist walls of the beaker, and are washed 
with 10 c.c. of distilled water on to a filter. The filtrate should give no 
turbidity, much less a precipitate of silver chloride, on the addition of 
a solution of silver nitrate. The genuine oil, that is, such as has been 
distilled from bitter almonds or from peach kernels, never gives a reaction 

for chlorine. 

The above-described method of testing the oil has proved to be 
infallible. In order, however, to be certain of the result, a control test 
should always be made with a pure distilled oil, since an incorrect 
opinion might be formed if the water and the vessels employed were 
not perfectly free from chlorides. 

Caraway Oil — From the fruits of Carum Carvi, Linne. 

^^5° 0-907-0-9I5 ; au+70 to +80°; soluble in 3-10 vols, of 80 per 



CONSTANTS AND PROPERTIES 271 

cent., or i vol. of 90 per cent, alcohol. Carvone content 50-60 per 
cent, (to be determined according to the sulphite method described 
on p. 265). 

Carvone {Carvol), C^^U^p.—d^'^" o-ge^-o-gGG ; boiling point 229"-230° ; 
"d +57°to +60" ; soluble in 16-20 vols, of 50 per cent, alcohol at 20° or 
in ^-2 vols, of 70 per cent, alcohol ; n^'^^° 1-497- 1-500. 

Cassia Oil, Chinese Cinnamon Oil. — From the leaves of the Chinese 
cinnamon, Citinamonuni Cassia^ Blume. 

d}^'' I-055-I-070; optically inactive or slightly l?evo- or dextro- 
rotatory ; soluble in 2-3 vols, and more of 70 per cent alcohol, 
usually with opalescence. Cinnamic aldehyde content (see p. 264) 75-90 
per cent. The residue obtained by distillation from a fractionating flask 
with a low side tube amounts to 6-8, or, at the most, 10 per cent. This 
residue should be pasty, but not hard or brittle, as would be the case if 
the oil were adulterated with colophony. Such an addition to the oil 
may also be detected in the following manner : — To a solution of 
I vol, of cassia oil in 3 vols, of 70 per cent, alcohol is added, drop 
by drop, an amount up to \ vol. of a freshly prepared solution of lead 
acetate in 70 per cent, alcohol, which has been saturated at the room 
temperature. If a precipitate is produced, it indicates the addition 
of colophony. 

Cinnamon Oil, Ceylon. — From the bark of Cinnanioninn zeylanicuniy 
Breyne. 

d}-^° 1-023-1-040; od laevorotatory to —1°; soluble in 2-3 vols, of 
70 per cent, alcohol ; cinnamic aldehyde content 65-75 per cent., as 
determined by the bisulphite method (see p. 264). 

Citronella Oil. — From the herb of Cymbopogon Nardus, Stapf. 

There are two sorts of this oil, the Ceylon and the Java, the latter 
being the more valuable. 

Ceylon Citronella Oil. — ^^° 0-900-0-920; au laevorotatory to —21". 
It should yield a clear solution with 1-2 vols, of 80 per cent, alcohol, 
and with 10 vols, of this solvent should give a solution which is at 
most opalescent, but which, on standing, should separate no drops of 
oil (Schimmel's Test). The oil should also meet these requirements 
after the addition of 5 per cent, of Russian petroleum (Stricter 
Schimmel's Test). The apparent amount of alcohol, C\oH^gO 
(geraniol + citronellal), as determined by acetylation, at least 57 per 
cent, (for method of determination see p. 263). 

Java Citronella Oil. — <a^^° 0-886-0-900; od laevorotatory to —5°; 
soluble in i or 1-2 vols, of 80 per cent, alcohol. Amount of alcohols, 
CjoHigO, usually more than 80 per cent. 

Clove Oil. — From the dried flower-buds of Eugenia caryopJiyllata^ 
Thunberg. 

d^^° 1-044-1-070; a-o laevorotatory to —1° 15'; soluble in 1-2 vols. 



272 ESSENTIAL OILS 

of 70 per cent, alcohol. Eugenol content 80-90 per cent, and 
more. 

Clove Sicui Oil'is distilled from the stems of cloves, d^^' i 040-1 065 ; 
optical rotation and solubility the same as clove oil. Eugenol content 
85-95 per cent. 

The determination of the eugenol is conducted either in a cassia 
flask (Fig. 49, p. 265), with a 3 per cent, solution of sodium hydroxide, 
or according to Thoms' improved method/ which also permits of 
determining the eugenol contained in the oil in the form of ester. 

This method is carried out as follows : — To 5 g. of clove oil are 
added 20 g. of a solution of sodium hydroxide (15 per cent.), and the 
mixture gently heated on a water-bath for half an hour, when a layer 
of sesquiterpene separates on the surface of the liquid. The contents 
of the beaker, while still warm, are brought into a small separator with 
a short discharge tube, and the eugenol-sodium solution, which soon 
settles well, returned to the beaker. The sesquiterpene which remains 
in the separator is washed twice with a 15 per cent, solution of sodium 
hydroxide, using 5 c.c. each time, and these washings added to the 
eugenol-sodium solution. To this solution 6 g. of benzoyl chloride are 
added, and the mixture shaken, whereb)- the formation of benzoyl- 
eugenol is at once effected, with the development of considerable heat. 
The last portions of unattacked benzoyl chloride are decomposed by 
heating for a short time on the water-bath. After cooling, the liquid 
above the solidified ester is removed by filtration, any small crystals 
which may have got on to the filter being washed with 50 c.c. of water 
into the beaker, and the mixture heated until the crystalline cake again 
forms an oil. After gentle agitation it is again allowed to cool, the 
supernatant clear liquid removed by filtration, and the cake, previously 
melted, washed twice in the same manner as before with water, using 
50 c.c. each time. To the bcnzoyleugenol, while still moist, 25 c.c. of 
alcohol (90 per cent, by weight) are immediately added, and the 
mixture heated on a water-bath, with gentle agitation, until solution is 
effected. After removing the beaker from the water-bath, the agitation 
of the contents is continued until the bcnzoyleugenol separates in the 
form of small crystals, which takes place within a few minutes. It is 
then cooled to a temperature of 17 , the precipitate brought on a filter 
of 9 cm. diameter, and the filtrate allowed to flow into a graduated 
cylinder, in which it may occupy a space of about 20 c.c. The alcoholic 
solution which may still be retained by the crystalline magma on the 
filter is displaced by the addition of so much alcohol (90 per cent, by 
weight) that the entire filtrate amounts to 25 c.c. The filter with the 
precipitate, while still moist, is transferred to a weighing tube, previously 
dried with the filter at loT' and weighed, and the whole heated at 101° 

• Arch. Pkarm., 1 903, 241, 592. 



CONSTANTS AND PROPERTIES 273 

until the weight is constant. At 17° the amount of pure benzoyleugenol 
dissolved by 25 c.c. of 90 per cent, alcohol is 05 5 g., and this weight 
must therefore be added to that of the quantity found. 

U a designates the amount of benzoic ester found, d the amount of 
clove oil used (approximately 5 g.), and if 25 c.c. of alcoholic solution 
are filtered from the ester under the above-mentioned conditions, then 
the percentage of eugenol in the clove oil is found according to the 
following formula : — 

4100(^ + 0-55) . 
6y.d 

This formula is derived from the two equations : — 

Benzoyleugenol Eugenol 

268 : 164 =(<3: + o-55): the amount of eugenol found. 

T-. , i64.(« + o-55) 

Eugenol = — =^^^^^7^ — ^^^. 
268 

Therefore, b : iM^+^iD = 100 : .^ir 

268 

_ i-64(^? + o-55). 100 ^ 4100(^ + 0-55) 
^ ~ - 268.^ 67. b 

Eucalyptus Oil. — From the leaves of Eticalyptus globulus, Labil- 
lardiere. 

d>^" 0-910-0-930; Od +1° to +15^; soluble in 2-4 vols, of 70 per 
cent, alcohol. An adulteration with the less valuable laevorotatory oil 
of Eucalyptus ainygdalina, LabilL, which consists almost entirely of 
phellandrene, Qo^ig. is tested for by adding to the oil, diluted in a 
test tube with twice its volume of light petroleum, a concentrated, 
aqueous solution of sodium nitrite. If now acetic acid be added in 
small portions, phellandrene nitrite will separate in a flocculent form 
in case this hydrocarbon be present. 

In order to determine quantitatively the cineol,^ the most important 
constituent of eucalyptus oil, 100 c.c. of the latter are distilled from 
the Ladenburg fractionating flask, described on p. 262, in such a 
manner that about one drop passes over per second. In the fraction 
boiling between 170° and 190°, after diluting it with an equal volume 
of turpentine oil, the cineol content is determined in the following 
manner: — To 10 c.c. of the mixture, consisting of the respective 
fraction and turpentine oil, and contained in a cassia flask of 100 c.c. 
capacity (p. 265), is added so much of a 50 per cent, resorcinol solution 
that the flask is about four-fifths filled. The mixture is then vigorously 
shaken for five minutes, after which the portions of oil which have not 
entered into the reaction are brought into the neck of the flask by 

1 Semi-annual Report of Schimmel & Co., October 1907, p. 47, and April 1908, p. 50. 
J. Soc. Chem. Ind.^ 1 908, 27, 90. 

Ill S 



274 ESSENTIAL OILS 

filling the latter with the resorcinol solution. As soon as the liquid 
has become perfectly clear, or nearly so, which usually requires several 
hours, the volume of unchanged oil is read off. Any drops of oil 
which may remain attached to the sides of the vessel are brought to 
the surface by a frequent rotation and tapping of the flask, and the 
amount of cineol thus determined is calculated to its percentage by 
volume in the original oil. The cineol content of good Eucalyptus 
globulus oils should be from 55-80 per cent. 

This method depends upon the property of cineol of forming an 
addition product with resorcinol which is soluble in water. 

Eucalyptol {Cineol), Z^^^f^. — d}^° 0-928-0-930 ; Oi, ±0^ ; boiling point 
I76''-I77°; ^n^o^ 1-458; melting point between +i°and +1-5°. 

Fennel Oil. — From the fruits oi Foeniculum vulgare, Miller. 

d^^° 0-965-0-977 ; ai,+ i2' to +18', rarely higher; soluble in 5-8 
vols, of 80 per cent, alcohol (sometimes with turbidity), and in 
I vol, of 90 per cent, alcohol. Congealing point (see p. 260), not 
below +5°. 

Geranium Oil. — From the leaves of different species o{ Pelargofiium. 
(Palmarosa oil is also incorrectly designated as Turkish or Indian 
geranium oil). 

d}^° o- 890-0- 907 ; an —6" to —16''; acid value 3-12; ester value 
42-78 ; soluble in 3 vols, of 70 per cent, alcohol, sometimes with separa- 
tion of a paraffin hydrocarbon. 

Lavender Oil.— From the flowers oi Lavayidula officinalis^ Chaix. 

^^''' 0-883-0-895 ; a,,-,—y to —9°; soluble in 3 vols, of 70 per cent, 
alcohol; linalyl acetate content 30-55 per cent, and more (for method 
of determination, see p. 262). 

The requirements of the German tax commissioners for a lavender 
oil which is to be used for denaturing purposes, but which are not 
sufficient for differentiating between adulterated and pure oils, are as 
follows: — The density of lavender oil at 15° should be between 0880 
and 0-900; 10 c.c. of lavender oil at 20° should )'ield a clear solution 
with 30 c.c. of spirit containing 6"^) per cent, by weight of alcohol. 

Lemon Oil. — Obtained by expression from the rind of the fruit of 
Citrus Lijnonujfi, Risso. 

d^^° 0-857-0-86I ; 0^+58" to ^-es" at 20"; soluble with turbidity in 
90 per cent, alcohol, but giving a clear solution with absolute alcohol. 
Residue on evaporation 2-5-3-5 P^r cent, (the method of determination 
is described under Bergamot Oil, p. 269). Among the numerous 
published methods for the determination of the citral content none 
has proved satisfactory. 

Lemon-grass Oil. — From the herb of Cyiiibopogon flcxuosus, Stapf. 

^/'^ 0-895-0-905 ; ay dextro- or kcvorotatory -f T to —5°; soluble 
in 2-3 vols, of 70 per cent, alcohol, but occasionally showing a slight 



CONSTANTS AND PROPERTIES 275 

turbidity by a further addition of the solvent. Citral content, determined 
by the bisulphite method (p. 264), 70-85 per cent., by the sulphite 
method (p. 265), 65-80 per cent. In reporting on the citral content 
it should be stated which method has been used for its determination. 

Citral, QoHipO.— ^15° 0-892-0-895 ; an±o°; 11^20° i -4880-1 -4886 ; 
boiling point 228°-229°. 

Linaloe Oil. — From the wood of different species o{ B7irsera. 

d^^° 0-875-0-890; «,, — 3' to —5°, less frequently dextrorotatory 
-1-3° to +8°; saponification value 1-25; soluble in 2 vols, of 70 per 
cent, alcohol. 

Mustard Oil, true. — From the seed of Brassica nigra, Koch, and 
Brassica Juncea, Hooker. 

d^^° I -014-1 -025 ; Od ± o' ; boils for the most part between 147° and 
153° (760 mm.); soluble in every proportion in 90 per cent, alcohol. 
Allyl isothiocyanate content more than 90 per cent. 

Mustard Oil, synthetic. — d^''>° 1-020-1-025; u^±d'. Boils chiefly 
between 150° and 153° (760 mm.). «d-° 1-527-1-529, 

Determination of the Allyl Isothiocyanate in Mustard Oil. — A method 
for the quantitative determination of sulphur in mustard oil has been 
devised by J. Gadamer^ and improved by M. Kuntze.^ The mustard oil 
is converted by ammonia into thiosinamine (allyl thiocarbamide), and 
the latter by an ammoniacal solution of silver nitrate into silver 
sulphide, allyl cyanamide, and ammonium nitrate, in accordance with 
the equation : — 

C3H5.NCS + 3NH3-f2AgN03 = Ag2S + C3H5.NCNH + 2NH,N03. 

In order that this reaction should proceed smoothly, a large excess 
of silver nitrate is necessary. If conducted in alcoholic solution, it is 
also necessary that this should be heated, as otherwise the results are 
too low. The excess of silver nitrate is titrated back with tV/io 
ammonium thiocyanate solution. 

For testing the mustard oil it is first converted into the Spirit of 
Mustard {Spij-itus Siiiapis of the German Pharmacopceia) by mixing 
2 g. of the oil with 98 g. of alcohol (sp. gr. 0-830-0-834). 

The determination is carried out as follows: — To 5 c.c. ( = 4-2 g.) of 
the spirit, contained in a flask of 100 c.c. capacity, are added 50 c,c. of 
N\io silver nitrate solution and 10 c.c. of solution of ammonia (sp. gr, 
0-960). After closing the flask with a cork, through which a glass tube 
I m. in length is passed, the mixture is heated for an hour on a water- 
bath in which the water is in active ebullition. It is then cooled to 15°, 
the flask filled to the 100 c.c. mark with distilled water, and the mixture 
filtered. In 50 c.c. of the clear filtrate, after the addition of 6 c.c, of 

1 Arch. Pharnu, 1899, 237, IIO, 372 ; /. Chetn. Soc. Ahslr., 1899, 76, ii., 712. 

2 Arch. Pharm., 1908, 246, 58 ; /. Chem. Soc. Ahsir., 1908, 94, ii. 440, 



276 ESSENTIAL OILS 

nitric acid (sp..gr. 1153), the excess of silver nitrate is determined by 
titration with .\'io ammonium thiocyanate solution, ferric ammonium 
sulphate or ferric sulphate being used as the indicator. 

Since 2 mols. of silver nitrate (M.VV. = 340) correspond to i mol. 
of allyl mustard oil (M.W. = 99), i c.c. Xjio silver nitrate solution 
( = 0017 g. AgXOg) is equivalent to 000495 g- of allyl mustard oil. 

Nutmeg Oil. — Distilled from nutmeg, the kernel of the seed of 
Alyristica fragratis, Houttuyn. 

d'^^' 0-S70-0-925 ; 00+7"^ to +30' ; soluble in 1-3 vols, of 90 per cent, 
alcohol. 

Orange Oil, bitter. — Expressed from, the rind of the fruit of the 
bitter orange, Citrus Bigaradia, Risso. 

d^^° 0-853-0-857 ; a„ +90" to +93° at 20° C. Does not form a clear 
solution with 90 per cent, alcohol. Residue on evaporation (see under 
Bergamot Oil, p. 269) 3-5 per cent. 

Orange Oil, sweet. — Expressed from the rind of the fruit of the 
sweet orange, Citrus Aurantiuni, Risso. 

dif 0-848-0-853 ; a^ +95° 30' to +98'^ at 20' C. Does not form a 
clear solution with 90 per cent, alcohol. Residue on evaporation 2-4 
per cent. 

Orange Flower Oil. Oil of Neroli. — A distillate from the flowers 
of the bitter orange. Citrus Bigaradia, Risso. 

d^-'' 0-870-0-880; au + i"" 30' to +8^; soluble in 1-2 vols, of 
80 per cent, alcohol, but on the further addition of the solvent a 
turbidity usually occurs owing to the separation of a paraffin ;. 
saponification value 24-55. 

Palmarosa Oil (also incorrectly termed Indian or Turkish 
Geranium Oil). — From the herb of Cymbopogon Martini, Stapf 

d^^" 0-888-0-900; a^ slightly dextro- or hevorotatory +6^ to —2° 
30'; soluble in 1-5-3 vols, of 70 per cent, alcohol; saponification 
value 14-46; saponification value after acetylation not below 225. 

Patchouli Oil. — From the leaves oi Pogostemon Patchouli, Pelletier. 

d^-' 0-970-0-995 ; ai,— 50° to —68''; soluble in i vol. of 90 per 
cent, alcohol. 

Peppermint Oil. — From the herb of Mentha piperita, Linne. 
There are various commercial sorts of this oil, of which the English, 
.American, and Japanese are the most important. 

English or Mitcham Peppermint Oil. — cP-'^" 0-900-0-9IO; «„ — 22^ to 
— 33"; soluble in 3-5 vols, of 70 per cent, alcohol. Amount of 
ester menthol {i.e. menthol present in the form of ester, calculated 
as menthyl acetate, Ci(,Hj(,0. COCII.;) 4-12 per cent. = saponification 
value 14-41 ; total menthol (free menthol + menthol ester) 50-63 per 
cent. = saponification value after acetylation 164-194. 

American Peppermint Oil. — a^'-'^' ogoo-o-gio ; a,, — 18'' to —33°. 



CONSTANTS AND PROPERTIES 277 

Some oils only dissolve in | vol. and more of 90 per cent, alcohol, 
whilst others are soluble in 4-5 vols, of 70 per cent, alcohol. Ester 
menthol 3-10 per cent, (saponification value 10-36), total menthol 
50-61 per cent, (saponification value after acetylation 158-188). 

Japanese Peppennint Oil. — At the ordinary temperature a normal 
oil is a semi-solid mass, interspersed with crystals of menthol. The 
commercial oils are mostly such as have been deprived of a part of 
the menthol, and which therefore vary exceedingly with respect to 
density, rotatory power, and menthol content. The differentiation of 
the individual sorts of peppermint by a physical and chemical examina- 
tion is very difficult, and impossible in the case of mixtures of 
different oils. 

Rose Oil. — From the flowers of Rosa daniascena, Miller. 

^^*^° 0-849-0-862 ; a^ — 1" 30' to —3°. On account of the paraffin 
hydrocarbons present, the oil does not give a clear solution with 90 
per cent, alcohol. Acid value 0-5-3-0; ester value 8-16; total 
geraniol content (geraniol + citronellol) 66-75 per cent, (see p. 263). 
Congealing point {i.e. the temperature at which the oil, when slowly 
cooled, begins to separate the stearopten or paraffins) +19° to +23°-5. 
In order to determine the congealing point of rose oil, 10 c.c. of the 
oil are brought into a test tube of 15 mm. diameter, and a thermometer 
then immersed in it so that it can move freely without touching 
the sides of the glass. After the test tube has been warmed to such 
an extent that all the stearopten is melted, the contents are slowly 
cooled until the first crystals appear. 

Rosemary Oil, Italian. — From the flowers of Rosmarinus officinalis^ 
Linne. 

^^° 0-900-0-920; a^ dextrorotatory to +15°; soluble in \ vol. 
and more of 90 per cent, alcohol. If from 50 c.c. of the oil, contained 
in the flask described on p. 262, 5 c.c. are slowly distilled off', the 
distillate should be dextrorotatory. If it is laevorotatory, this is 
almost always due to an adulteration with French oil of turpentine. 
It should, however, be noted that there are also pure natural products 
of which the first 10 per cent, which passes over is slightly laevo- 
rotatory. The German tax commissioners no longer give definite 
directions for the examination of rosemary oil which is to be used for 
denaturing fatty oils. 

Sandalwood Oil. — From the wood of Santaluni album, Linne. 

(^^° 0-975-0-983 ; un—i^" to —20''; soluble in 5 vols, of 70 per 
cent, alcohol at 20°, and this solution should not be rendered turbid by 
the further addition of 70 per cent, alcohol ; saponification value 5-20. 
Santalol content, calculated for C^gH^^O, at least 91 per cent, (for 
method of determination, see p. 263). 

Sassafras Oil. — From the root of Sassafras officinalis, Nees. 



278 ESSENTIAL OILS 

d^'"" I -070- 1 -082 ; rtu+3 to +4'; soluble in 1-2 vols, of 95 per 
cent, alcohol. 

Safrol, CioHj.,Oo.— ^^' 1105-M07; a^ ± O \ boiling point 233° 
(760 mm.); 71^20° i-536-i-540. Congealing point 11 . Safrol often 
solidifies with great difficulty, and the crystallisation should therefore 
be initiated by introducing a crystal of the substance. 

Spike Oil. — Distilled from the flowers of Lavandula Spica, DC. 

f/'' 0-905-0-9I5; a^ dextrorotatory to +7"; soluble in 1-5-3 ^'o^^- 
of 70 per cent, alcohol. The best spike oils dissolve in 15-20 vols, 
of 60 per cent, alcohol. Saponification value 5-20. 

Star-anise Oil. — From the fruits of Illiciuui atnsatinn, Linne. 

d^^° 0-980-0-990 ; od slightly laevorotatory to — 2', seldom slightly 
dextrorotatory; soluble in I-5-2-5 vols, of 90 per cent, alcohol. 
Congealing point (see p. 260) + 15'' to + i8^ 

Thyme Oil. — From the fresh flowering herb of Thymus vulgaris, 
Linne. 

(P^'"'' 0-900-0-9I5; a^ slightly l.-evorotatory ; phenol content (thymol 
and carvacrol) 20-30 per cent, (for method of determination see p. 266) ; 
soluble in 1-2 vols, of 80 per cent, alcohol. 

Tliymol, CioHi^G. — d^-'' 1-028; crystallised thymol sinks in water, 
but in a fused state floats upon it. Melting point 50-51° ; boiling point 
228"-23o' ; readily soluble in alcohol, ether, chloroform, and the aqueous 
.solutions of caustic alkalis, but very slightly soluble (i : iioo) in pure 
water. 

Turpentine Oil. — Distilled from the turpentine of various species 
of Pi)ius. 

American Turpenti?ie Oil. — ^^^° 0-865-0-870; a^ dextrorotatory to 
-f 15", very seldom slightly laevorotatory; soluble in 5-7 vols, of 
90 per cent, alcohol, old resinified oil being more readily soluble. On 
distillation 85 per cent, passes over between 155' and 163^ 

French Turpentine Oil.—d>^° 0-865-0-876; od - 20' to -40°. The 
other properties are the same as those of the American oil. 

Spanish Turpentine Oil — This possesses the same constants as the 
French oil. 

Grecian Turpentine 6>//.— rt!^^° 0-863-0-870 ; a,, +36' to -(-40. Other- 
wise the same as the American oil. 

Pine-tar Oil (Ger. Kienol) is a product of the dry distillation of coni- 
ferous roots, and may be recognised by its disagreeable, empyreumatic 
odour, d^-'" 0-862-0-875; aD+14' to -I-24.'' It boils between 160' 
and 180'. 

Turpentine oil has been much adulterated in recent years, chiefly 
with fractional products from petroleum (benzine, etc.), rosin essence, 
carbon tetrachloride, pine-tar oil, and many other substances. The 
detection, and especially the quantitative determination of these 



CONSTANTS AND PROPERTIES 



279 



™, 



!J?, 



additions, is often difficult ; for a critical consideration of the respective 
methods reference should be made to the work of J. Marcusson and 
H, Herzfeld.i 

An addition of benzine may be recognised by a lowering of the 
specific gravity, since that of pure turpentine oil is between 0-865 ^^^^ 
0-875, whilst the benzine fractions commonly used to adulterate it, 
which boil from ioo''-i8o°, have a density between 0-73 and oSo. The 
indices of refraction are also different, that of turpentine oil being 
I-47I-I-4735 and that of benzine 1-419-1-450. According to Herzfeld 
the addition of benzine may also be recognised by fractional distillation. 
In the case of a pure oil the refraction indices of the individual fractions 
will differ but slightly from each other, whereas 
the portions containing benzine will exhibit great 
differences. 

The quantitative determination of petroleum in 
turpentine oil is carried out according to W. M. 
Burton - as follows : — 300 c.c. of fuming nitric acid 
are allowed to drop slowly from a dropping funnel 
into 100 c.c. of the adulterated oil, contained in a 
capacious flask provided with a reflux condenser, the 
mixture being kept well cooled. The product of the 
reaction is then washed with hot water, and the 
residual petroleum weighed. 

For this method of determination H. Herzfeld^ 
has constructed a small apparatus (Fig. 50), which 
renders it possible directly to read off the amount 
of mineral oil which has not been attacked by the 
nitric acid. 

Herzfeld^ subsequently recommended the use of 
fuming sulphuric acid in the place of nitric acid. 
10 c.c. of the turpentine oil to be tested are allowed 
to drop slowly, with moderate cooling, into 40 c.c. 
of concentrated sulphuric acid. After ten to twelve hours from 8-9 
per cent, of the turpentine oil used will separate. The lower dark 
brown layer is then drawn off, and the residual oil again shaken with 
3-4 c.c. of fuming sulphuric acid. After standing for several hours 
only 0-I-0-2 c.c. of oil will then separate, whereas if a mineral oil be 
present, the volume will be correspondingly greater. 

According to Marcusson it is better to treat the sample of oil at 
— lo' with fuming nitric acid ; but opinion is still divided respecting the 
relative merits of the nitric acid and sulphuric acid methods. The 

1 CAem. Zeit., 1909, 33, 966, 985, 1081 ; 1910, 34, 285 ; 1912, 36, 413, 421. C/. also / Soc 
Chem. Ind,, 1909, 28, 1096. 

2 Amer. Chem. J., 1890, 12, 102 ; /. Soc. Chem. Ind., 1890, 9, 557. 

3 Chem. Zentr., 1903, i, 258. *^Ibid., 1904, i, 548. 




Fig. 60. 



280 ESSENTIAL OILS 

results vary greatl}', especially for the reason that the different sorts of 
petroleum (from America, Russia, Galicia, Sumatra, and Borneo) show 
a very different behaviour towards the two acids. 

Pine-tar oil may be recognised by the fact that a fragment of 
potassium hydroxide, when brought into the liquid, will soon become 
coated with a )-ellovvish-brown layer. In the case of pure turpentine 
oil, considerable time will elapse before the formation of such a layer 
occurs. Old, resinified oils should be distilled before the application of 
this test. Pine-tar oil, in amounts of not less than lo per cent, may be 
detected by the yellowish-green coloration produced by sulphurous 
acid (Herzfeld's reaction).^ 

Rosin essence may be recognised, apart from the low temperature 
at which the liquid begins to boil, by Grimaldi's reaction, which 
depends upon the collection of fractions of oil, in armounts of 3 c.c. each, 
up to a temperature of 170°, and the green coloration which they 
yield with a fragment of tin and hydrochloric acid. 

Carbon tetrachloride, which, on account of its higher density, is used 
to conceal an adulteration with benzine, may easily be detected by 
Beilstein's copper test, or by the separation of potassium chloride when 
boiled with an alcoholic solution of potassium hydroxide, as also by 
fractional distillation. For its quantitative determination when mixed 
with turpentine oil and benzine, the chlorine content of the mixture is 
determined according to the method of Carius. Pure carbon tetra- 
chloride contains 92-2 per cent, of chlorine. 

^ Cf. also Wolff, Chem. Zeit. Rep., 1912, 36. 64 ; /. Soc. Chem. Ind., 1912, 31, 692 ; and Piest, 
Chem. Zeit., 1912, 36, 198 ; /. Soc. Chem. Ind., 1912, 31, 239. 



Literature. 

GiLDEMEiSTKR, E., AND HOFFMANN, F. — Die AetJierisclien Oele, 2nd edition, vol. i., 

1910 ; vol. ii., 1913. 
English translation of above by E. Kramers. The Volatile Oils, first edition, 1900; 

second edition, vol. i., 1913. 
Parry, E. J. — The Chemistry of Essential Oils and Artificial Perfuvies, 2nd edition, 

1908. 
Semmler, F. W. — Die Aethetischen Oele, 1906-7, 4 vols. 



TARTARIC ACID 

By W. Klapproth, Dr Ing., Chemist to Messrs C. H. Boehringer, Nieder-Ingelheim, 
on Rhine. EngHsh translation revised by W. A. Davis, B.Sc, Rothamsted 
Experimental Station. 

The residues from the manufacture of wine are the raw materials for 
the tartaric acid industry. From these residues are manufactured 
tartaric acid, cream of tartar, and several other salts of tartaric acid, 
such as Rochelle salt, normal (" neutral ") potassium tartrate, tartar 
emetic, and tartrate of iron. 

These raw materials may be classified as follows : — Lees, taj'tars 
(especially the so-called " almnbic^' and " vinaccia " tartars) and " tartrate 
of limey They are obtained by drying, or by crude processes of 
crystallisation, or precipitation, from the residues obtained in the manu- 
facture of wine. The tartaric acid is present in these materials in the 
form of potassium hydrogen tartrate (bitartrate), or as normal calcium 
tartrate, or as a mixture of both these substances ; the proportions are 
very variable. 

Wine-lees, the sediment that settles out from the completely 
fermented must, is the most important raw material. In the moist 
condition, as obtained by pressing out the new wine from this sediment, 
lees form a sticky, clay-like mass, with an odour of wine, and having a 
dirty yellow to dark red colour. The lees are dried as quickly and 
rapidly as possible, in order to avoid the decomposition of the tartaric 
acid by the growth of moulds or bacteria, and are usually put on the 
market in this form as dried lees. They consist of yellowish to dark red, 
irregularly shaped lumps, with an average size about that of a walnut. 
The content of tartaric acid is usually between 15-30 per cent, but is 
sometimes as high as 40 per cent., although lees of the latter grade are 
seldom or never worked in this country. The tartaric acid is present 
as acid potassium tartrate and calcium tartrate in variable proportions. 
The rest of the material is made up of the dried yeast-cells, small 
amounts of inorganic salts, and " impurities " which arise from the grape- 
juice, or from the materials used in treating the wine (grape-skins, 
stalks, pips, clay, sulphur, sand, and gypsum). Lees are differentiated 
according to the place of origin as Italian, Spanish, French, Austrian, 
and Levantine. The last-named includes Dalmatic, Greek, Turkish, 
and South Russian lees. Lees show very marked differences, especially 

281 



282 TARTARIC ACID 

as regards working, according to their place of origin ; analyses have 
been published by Warington, Rasch, and Ciapetti.^ 

The name of" Tartars" comprises the raw materials which contain 
more than 40 per cent, of tartaric acid. A distinction is to be made 
between cask-tartars, obtained by the chipping of the scale from wine 
casks, and the tartars obtained by boiling out with water the lees and 
ma?c or vinacce from the manufacture of wine, and subjecting the 
liquors to crystallisation ; tartars obtained in this latter way form the 
hicrher-<irade tartars, such as Vinacda tartar. The best half-refined 
tartar, known as St Antinio tartar, serves for the manufacture of cream 
of tartar, Rochclle salt, and other tartaric acid salts. 

Linio, Sablon, and Tartrate of Lime are raw materials obtained by 
the precipitation of tartaric acid in tartar works or wine-distilleries. 

I. Raw Materials. 

Owing to the relatively high value of raw materials for the manu- 
facture of tartaric acid and the fact that they are frequently very 
far from uniform in character, the sampling must be carried out with 
very special care. For this purpose a portion of the material is taken 
from each cask or sack, and in general the procedure described in Vol. 
I., Part I., pp. 12-14 is followed. The material is first coarsely ground 
in the factory mill during the sampling, and then, before analysis, again 
finely ground in the laboratory in an ordinary small hand-mill (coffee 
mill) kept solely for this purpose. 

In judging the raw material, both the total percentage of tartaric 
acid and the percentage of tartaric acid present as bitartrate 
are of importance ; the former is necessary in all branches 
of the tartaric acid industry, whilst the latter is essential in the 
manufacture of cream of tartar and of salts of tartaric acid. The 
analytical results for the so-called " Total acid " are given as the 
percentage of tartaric acid in the raw material ; the " Bitartrate " is 
expressed either as the percentage of potassium h}-drogen tartrate, or 
as its equivalent in tartaric acid. In England the latter method has been 
generally used in the analysis of lees and tartars. It is not a general 
practice to return the percentage of moisture present in the sample, 
although by neglecting this, not only can differences of analysis arise, 
but also an essential factor for judging the raw material is left out of 
account. Insufficiently dried samples often lose several per cent, of 
tartaric acid in a few weeks, owing to the development of moulds and 
bacteria ; even apparently well-dried samples of lees, when kept in 
carefully sealed glass bottles, have been shown to lose from 1-3 per cent, 
of their tartaric acid in five years. Moreover, slimy substances are 

^ See Literature, p. 295. 



RAW MATERIALS 283 

produced in insufficiently dried material owing to the growth of moulds, 
and these give trouble in subsequent factory working. It is therefore 
desirable to determine the percentage of moisture obtained by drying 
the sample at ioo°. 

In estimating either the bitartrate or the total tartaric acid, the 
tartaric acid is precipitated in the form of the acid potassium salt, which 
is then determined by titration. For the titration, A710, A^/5, NJ2, or 
Ay I potassium hydroxide is used, which must be free from carbon 
dioxide ; it is standardised by titration with specially recrystallised 
potassium hydrogen tartrate (dried at 100") under exactly the same 
conditions of concentration as are used in the actual determination. As 
indicator, sensitive reddish-violet litmus paper is used exclusively ; the 
same paper must be used in standardising as in the actual estimation. 
The test is made by " spotting." 

The molec. wt. of tartaric acid = 150. 

„ „ potassium hydrogen tartrate = 188. 

I. The Estimation of Acid Potassium Tartrate (Bitartrate). 

An approximate es.timation of bitartrate is effected by simple 
titration. With lees of average quality containing from 20-30 per 
cent, of tartaric acid, the results obtained in this way are from 3-5 per 
cent, higher than the true bitartrate values, owing to the presence of 
acid salts and organic substances of acid character ; with unadulterated 
tartars the difference is smaller. This method does not accordingly 
indicate the adulteration of the raw material with acid substances such 
as alum. 

Approximate results are also obtained by several other methods 
which were formerly in use, such as the " Ignition method " and the 
" Methode a la casserole." In the former method, the material was 
burnt, the ash extracted with water and the dissolved potassium 
carbonate estimated. In the French " casserole test," the sample was 
extracted with boiling water and the crystals which separated on 
cooling weighed. The methods described in detail by P. Carles ^ are 
not applicable, because when certain impurities are present, either by 
accident or design, quite incorrect results are obtained. 

The method of Philips & Co.'-^ consisted in exactly neutralising the 
bitartrate with potassium hydroxide and reprecipitating it from the 
filtered solution by acetic acid and alcohol. When other calcium salts 
are present, such as gypsum, the results obtained are too high. 

F. Klein ^ boils the sample with water, evaporates the filtered solu- 
tion to a small volume, and precipitates the bitartrate by adding 
potassium chloride. The precipitate is filtered off, washed with a 10 per 

1 Les Derives Tartriques, 1903 ; Z. angew. Ckem., 1898, II, 183. 

2 Z. anal. Chem., 1890, 29, 577. ^ Ibid., 1885,24, 379. 



284 TARTARIC ACID 

cent, solution of potassium chloride which has previously been saturated 
with the bitartrate, and then titrated. This method, which is based on 
Warington's process for the estimation of the total tartaric acid, is not 
now in general use, although it gives good results ; it has been much 
recommended by Fabre.^ 

The most-used commercial method, the so-called " Oulman's 
method," is described by Stiefel- as follows :— 3-76 g. of the finely 
powdered tartar is placed in a litre flask, 750 c.c. of water added, the 
latter heated to boiling and kept in ebullition for not more than 
five minutes. The flask is then filled to the mark with distilled water 
and allowed to cool. After cooling, the volume is adjusted to the exact 
litre and the solution filtered through a dry filter. Of this solution, 
500 c.c. are evaporated to dryness on the water-bath in a porcelain 
dish, the residue moistened with 5 c.c. of water, and after cooling, mixed 
with 100 c.c. of 95 per cent, alcohol. After standing for thirty minutes 
the alcohol is decanted through a dry filter paper, allowed to drain 
thoroughly, and any potassium bitartrate which has passed on to the 
filter paper is washed back into the dish with boiling water. The 
solution is then made up to about 100 c,c. and titrated whilst hot with 
A75 potassium hydroxide. To the number of cubic centimetres of 
alkali used 0-2 c.c. is added to correct for the loss of bitartrate in the 
alcohol mother liquors. 

All methods for estimating bitartrate are scientifically not quite 
accurate, as changes may occur in boiling out the samples ; for this 
reason, too prolonged boiling should be avoided. 

2. The Estimation of the Total Tartaric Acid. 

The older methods of Scribani, Scheurer-Kestner, and Oliveri, 
based on the precipitation and weighing of calcium tartrate, have been 
abandoned on account of their inaccuracy. 

The first scientifically sound method was that of R. Warington,^ 
the principle of which is as follows : — The calcium present was 
precipitated as oxalate by means of neutral potassium oxalate, the 
mass neutralised with potassium hydroxide, the whole filtered, and 
the tartaric acid in solution separated by means of citric acid in 
presence of potassium chloride. This method, which was improved 
by Grosjean* and A. Borntrager,'* although in use commercially for 
many years, and until recently exclusively in this country, has been largely 
abandoned owing to its tediousness and also to the fact that it gives 
decidedly high results in presence of impurities such as phosphates. 

The method which is now in general use for the estimation of 

1 Chem. Zeit. Rep., 1899, 23, 4. ^ Das Raffinieren des WeinsUins, 1894. 

V- Chem. Soc, 1875, 27, 925. * //>ul, 1879, 35, 341 i 1883, 43. 33i- 

^ Z. anal. Client., 1886, 25, 327 ; 1S87, 26, 699. 



TOTAL TARTARIC ACID 285 

the total tartaric acid is the " Goldenberg Method, 1898," and its 
modification known as the " Goldenberg Method, 1907." 

These methods are based in principle upon a process, apparently 
due to Jules, and described in detail by the firm of Goldenberg, 
Geromont & Co., which was adopted in the industry under the name 
" Original Goldenberg Method." ^ This method was carried out as 
follows : — The substance was boiled with an excess of potassium 
carbonate, whereby the calcium was precipitated as carbonate, and 
the tartaric acid converted into the normal potassium salt ; the solution 
was then filtered and an aliquot portion of the filtrate precipitated by 
acetic acid and alcohol, the precipitated bitartrate being washed with 
alcohol and titrated. This method is subject to the following errors : — 
The potassium hydrogen tartrate is not quite insoluble in the mixture 
of dilute alcohol and acetic acid; on the other hand, especially in the 
case of wine-lees, other acid substances (pectic material) are precipi- 
tated and finally titrated as bitartrate. The results were, therefore, 
uniformly considerably higher than the true tartaric acid content, and 
depended on the excess of potassium carbonate employed ; further, 
the solutions of bitartrate finally titrated were always highly coloured, 
so that the results obtained by different analysts often differed widely, 
sometimes by several per cent. 

These difficulties are avoided in the " Hydrochloric Acid Method," 
also due to the firm of Goldenberg, Geromont & Co. The first form 
of the method published in 1888- was defined in greater detail 
in 1898.3 

The ''Goldenberg Method, 1898." 

This method is carried out as follows : — 6 g. of finely ground and 
powdered lees are stirred into a uniform mass with 9 c.c. of dilute 
hydrochloric acid (sp. gr. i-i), and allowed to stand during one hour at 
the ordinary temperature, with frequent stirring. The mixture is then 
diluted with an equal volume of water and again left for an hour, 
stirring from time to time. The mass is now washed into a 100 c.c. 
measuring flask, and the volume made up to the mark. After shaking 
well, the solution is filtered through a dry filter paper into a dry vessel ; 
50 c.c. of the filtrate are then measured into a beaker which is kept 
covered with a clock-glass, and carefully boiled with 18 c.c. of a 
potassium carbonate solution (10 c.c. = 2 grm. K.^COy) for ten minutes 
until the calcium carbonate is separated in a granular form. After 
washing the clock-glass with water, the contents of the beaker are 
filtered and the beaker washed with boiling water until the washings 
are neutral ; the calcium carbonate on the filter paper is also 
thoroughly washed out with boiling water, the alkaline liquid being 

1 Z. anal, Chem., 1883, 22, 270. ^ C/iet)!. ZciL, 1888, 12, 390 

'^ Z. anal. Chem., 1898, 37, 312, 383. 



286 TARTARIC ACID 

finally transferred to a porcelain dish. The liquid is then 
evaporated to about 15 c.c, and, after covering the dish with a 
clock-glass, carefully mixed while hot with 3 c.c. of glacial acetic acid. 
After stirring for five minutes the analysis may be completed, or, if 
necessary, left for some time, even to the next day if desired. This 
long standing, however, should be avoided in the case of low-grade 
lees, as a slimy precipitate may separate from which it is difficult 
subsequently to wash out the acetic acid completely. If, for any reason, 
the analysis must be interrupted at any other point, this is best done 
after measuring out the 50 c.c. of the hydrochloric acid solution. 

After stirring with acetic acid, 100 c.c. of 94-96 per cent, alcohol is 
added, rinsing the clock-glass therewith as it is run in ; the mixture 
is then stirred continuously during another five minutes, until the 
precipitate, which first separates as curds, has become finely granular- 
crystalline. The precipitate of bitartrate is now immediately trans- 
ferred to a conical suction-filter in the following way : — The precipitate 
is first allowed to settle in the dish in the ordinary manner, and the 
alcohol decanted off through the filter paper ; the precipitate is then 
washed on to the paper and the dish washed out with alcohol until 
there is no further acid reaction. The precipitate on the filter is also 
washed with alcohol until 30 c.c. of the alcoholic filtrate mixed with 
phenolphthalein shows an alkaline reaction after adding 2-3 drops of 
iV/5 potassium hydroxide ; this quantity of alkali is that required to 
overcome the slight acidity of the alcohol employed. Finally, the 
precipitate, together with the filter paper, is transferred to a beaker, the , 
bitartrate adhering to the porcelain dish and clock-glass being also 
washed in by means of boiling water, so that a total volume of from 
100-120 c.c. of liquid is obtained. This is titrated with iV/2 potassium 
hydroxide; Nji potassium hydroxide can be used if a burette of 10 c.c. 
capacity, graduated in ^V c.c, be employed, so that accurate readings 
to within -j-^ c.c. can be obtained. To recognise the end point sensitive 
litmus paper, with a reddish-violet colour, is u.sed. The alkali used 
must be standardised with chemically pure potassium hydrogen 
tartrate, using the same litmus paper and about the same concentra- 
tion of solution as in the actual analyses. The calculation is corrected 
in the following way for the volume of lees-residue remaining 
undissolved by hydrochloric acid in the first instance : — With a tartaric 
acid content of 20 per cent., a deduction of 07 per cent, is made; and 
the apparent value (20-I-;/) per cent, is counted as (20 + ;/) per cent. - 
(07 + 0-02;/) per cent, tartaric acid. 

In analysing tartars and tartrate of lime, 3 g. of substance is 
employed, which is digested with 9 c.c. of hydrochloric acid, diluted to 
100-5 c.c, and 50 c.c, of the filtrate is used for the analysis, as above. 
In these cases the above correction is avoided. 



TOTAL TARTARIC ACID 287 

In the case of normal raw materials, not too much contaminated by 
factory impurities, this method gives results corresponding with the actual 
tartaric acid content. High results due to adulterants are not possible. 
Experience, however, has shown that certain points were not sufficienlly 
defined, considerable differences being found in the results of different 
analysts, especially in the case of lees rich in calcium tartrate. The 
manner in which the potassium carbonate was added to the hydro- 
chloric acid solution — whether rapidly or slowly— and the time of 
heating, etc., were found to affect the result. These differences are not 
so pronounced when, conversely, the hydrochloric acid solution is added 
slowly to the potassium carbonate. In order to obviate them the exact 
details of procedure to be adopted were discussed at the International 
Congresses of Applied Chemistry held at Rome in 1906, and at London 
in 1909, and the following modification was agreed upon, which is, in 
the main, that worked out by Messrs Ogston and Moore.^ This 
modification is known as : — 

The " Goldenberg Method, 1907." 

This revised form oj the Goldenberg method is carried out as 
follows : — 6 g. of the sample if it contains more than 45 per cent, of 
tartaric acid, or 12 g. if it contains less than 45 per cent, is stirred 
continuously during ten minutes with 18 c.c. of hydrochloric acid of 
sp. gr. I- 10. The mass is then washed into a 200 c.c. measuring flask, 
made up to the mark with distilled water, and, after shaking well, the 
solution is filtered through a dry, fluted filter into a dry beaker. 100 
c.c. of the filtrate is then measured out by a pipette (the volume of 
which agrees exactly with the graduated flask — " standard " measuring 
vessels should be used by preference) and added to 10 c.c. of a solution 
of potassium carbonate containing 66 g. of the anhydrous salt per 100 
c.c. (sp. gr. 1-490). The solution of the potassium carbonate is placed 
in a beaker of 300 c.c. capacity, which should be covered with a clock- 
glass during the addition of the lOO c.c. of acid solution. After mixing, 
the solution is boiled gently for twenty minutes, until the calcium 
carbonate has separated in a crystalline form. The liquid is then 
washed into a 200 c.c. measuring flask, cooled, made up to the mark, 
and filtered through a dry, fluted filter paper. 

100 c.c. of the filtrate is then evaporated, either in a porcelain dish- 
on the water-bath, or in a beaker of Jena glass, on a hot plate, until the 
volume is about 15 c.c. Whilst the solution is still hot 3-5 c.c. of 
glacial acetic acid is added gradually, and with constant stirring, and 

1 Z. anal, Chem., 1908, 47, 57. Report of Internalional Committee on Analysis, 7th Inter- 
national Congress of Applied Chemistry, London, 1909. 

^ Porcelain basins having a blue ring on the inside to show the volume of 15 c.c, can be 
obtained from B. W. Haldenwanger, Charlottenburg. 



288 TARTARIC ACID 

the stirring continued for five minutes afterwards. After standing for 
ten minutes longer, lOO c.c. of 95 per cent, alcohol is added and the 
mixture again stirred during five minutes. After a further ten minutes' 
interval, the precipitate of bitartrate is filtered by the aid of a vacuum 
pump ; for this filtration a perforated disc of lead or porcelain is used, 
with a filter paper cut slightly larger than the disc. Asbestos pulp can 
also be used. The precipitate is then washed with alcohol until the 
washings cease to give an acid reaction, the washing being continued 
until 30 c.c. of the filtrate, mixed with phenolphthalein, require exactly 
the same volume of Nj^ alkali to produce redness as 30 c.c. of the 
alcohol itself The filter with the precipitate is washed into a porcelain 
dish with about 200 c.c. of boiling water, and then titrated with iV/S 
potassium (or sodium) hydroxide solution, using sensitive litmus paper ^ 
as indicator (spot test). 

The alkali must be standardised with chemically pure potassium 
hydrogen tartrate (dried at 100) using the same litmus paper and 
approximately the same concentration of solution. 

As the volume of the insoluble constituents of the raw material has 
not been taken into consideration the following corrections are 
necessary : — It has been agreed to deduct 0-8 per cent, for raw material 
yielding less than 45 per cent, of total tartaric acid, 0-3 per cent, for 
raw material with 45-60 per cent, and 02 per cent, for material with 
60-70 per cent. No deduction is made in the case of samples with 
more than 70 per cent, of acid. 

The "1907 Method" gives slightly higher results than the "1898^ 
Method," by an amount which varies between 02 and 0-7 per cent. 
In consequence a slightly lower valuation of the raw material is 
found with the new method. Both methods are in use, some dealers 
preferring to use the one, some the other method. As compared with 
the older Warington method, the Goldenberg 1907 method gives 
results from I-5-I7 units lower; that is, a difference in the case of 
lees of about 6 per cent, and in the case of tartars of 3 per cent, on the 
tartaric acid present. 

Several other methods have been proposed for estimating tartaric 
acid, but none of these has been generally adopted. It will be 
sufficient therefore to give the references. 

J. Mosczenski.- — Extraction of the material with sulphuric acid, and 
direct precipitation with potassium acetate. 

K. Ulsch.'* — Action of the material on platinised iron powder, and 
measurement of the hydrogen liberated. 

H. Ley.^ — Precipitation and weighing as zinc tartrate. 

' The most suitable sensitive litmus paper is that obtainable from E. Merck, Darmstadt, or 
E. Dieterich, Ilelfenberg. " Z. anal. CJiem., 1900, 39, 57- 

■' Z. anal. Clutn.^ 1901, 40, 614. ■• Pharm, Ztit.y 1904, p. 149. 



IMPURITY RATIO 289 

P. Carles.^ — Precipitation of a hydrochloric acid extract with 
calcium acetate, and weighing of the separated crystals of calcium 
tartrate. 

The following are references to more recent methods : — 

A. C. Chapman and P. Whitteridge, Analyst, 1907, 32, i63* 
P. Pozzi-Escot, CoDiptes rend., 1908, 146, 103 1. 
A. Kling, Comptes rend., 1910, 150, 616. 
C. Beis, Bull. Soc. Chim., 1910, 7' 697. 

3. Other Estimations. 

The adulteration of the raw material employed in the manufacture 
of tartaric acid, for example with alum, was formerly practised when 
samples were examined merely by simple titration ; since the intro- 
duction of the Warington and Goldenberg methods, such adulteration 
is no longer met with. The addition of alum would in fact cause an 
apparent loss of real tartaric acid in the Goldenberg method. 

When the final mother liquors ("Old Liquors") of the tartaric acid 
industry, in which impurities such as alumina, iron, and phosphoric 
acid have accumulated, are precipitated in the form of calcium tartrate, 
the harmful impurities tend to separate also. The working up of these 
old liquors is attended with difficulties. It, therefore, may happen that 
a parcel of raw material is contaminated with such a product. Such 
adulteration, which can in many cases be detected by smell, is also 
recognised by estimating the ratio of phosphoric acid, alumina, and iron 
to the total tartaric acid present {Inipiirity Ratio). For this determina- 
tion a portion of the sample is ignited ; if much calcium tartrate be 
present, it is advisable to moisten the material with a concentrated 
sugar solution in order to avoid loss. The ash is extracted with 
hydrochloric acid, and in the acid extract phosphoric acid, alumina, and 
ferric oxide are estimated ; it is generally sufficient to precipitate the 
three substances together by adding ammonia, and to weigh the whole 
after ignition. The amount found is calculated as a percentage of the 
total tartaric acid present. 

To estimate the proportion of iron the ignited material is dissolved 
by boiling with dilute sulphuric acid, cooled, reduced with iron-free zinc, 
and the solution titrated with iV/io potassium permanganate. 

The "Impurity Ratio" determined in this way is, in general, for 
tartars, less than i, for lees from 1-2, and only seldom in the latter case 
reaches 5-6; in impure factory products the ratio reaches 10-20. 

By slow or unsatisfactory drying, slimy substances may be formed 
in lees, owing to the growth of moulds or bacteria which render the 
subsequent working up of the products very inconvenient. It is, 

^ Les Derives Tartriques, I903, p. 105. 
Ill T 



290 TARTARIC ACID 

therefore, necessar\' to ascertain in many cases whether a material 
contains an undesirable quantity of such fermentation organisms. This 
is done as follows, according to the method given by H. Rasch^ : — 40 g. 
of lees are mixed with 50 c.c. of 10 per cent, calcium chloride solution 
in a beaker of 400 c.c. capacity, and exactly neutralised with milk of 
lime in the cold. The beaker is filled up with water, and the mixture 
allowed to stand for twenty-four hours at a temperature of 35". W'ith 
good, well-dried lees no visible fermentation should begin during this 
interval ; at most, a few bubbles of carbon dioxide should be evolved. 
The auxiliary materials of the industry, such as sulphuric acid, lime, 
chalk in the case of tartaric acid, sodium and potassium carbonates 
in the manufacture of tartaric acid salts, must naturally be as free as 
possible from alumina, iron, and phosphoric acid. A small amount of 
magnesia in the lime or chalk is not prejudicial in the case of tartaric 
acid (as it is in the case of citric acid), because magnesium tartrate is 
not very sparingly soluble. 

II. Control of Working Conditions. 

The impurities which accumulate in the works liquors, which consist 
mainly of phosphoric acid, alumina, and iron, are of importance as 
regards the estimation of the contained tartaric acid. It has been 
shown by Lampert^ that if litmus be used as the indicator in the 
titration of the tartaric acid a certain amount, which is recoverable in 
the actual working, escapes estimation. Rasch^ has therefore recom- 
mended the use of phenolphthalein in dealing with works liquors, with 
which fairly accurate results can be obtained even though the end- 
points are by no means sharp in the case of the cruder liquors. 

In the laboratory of Messrs C. H. Boehringer, it is considered 
preferable first to remove the iron, the principal impurity, by the 
following method : — 50 c.c. of the liquor are measured into a beaker 
and titrated with a standard solution of potassium ferrocyanide, using 
copper sulphate as outside indicator in the usual way, until a slight 
brown coloration is shown. The number of cubic centimetres of ferro- 
cyanide used gives a measure of the iron present. 50 c.c. of the 
original liquor are then measured into a 100 c.c. flask, mixed with the 
volume of potassium ferrocyanide found in the previous experiment to 
be necessary, made up to the 100 c.c, filtered, and the tartaric acid 
estimated in a measured volume of the filtrate. The estimation of the 
iron in the works liquors is a useful means of controlling the purity of 
these liquors, as the other impurities stand in a nearly constant ratio to 
the content of iron. 

^ Fabrikation der IVeinsautr, p. 44. 

'■* C/iem. Zei/., 1800, 14, 903 ; c/. also Ordonneau, Bu//. Soc. Chim., 1910, 7i I034» 
' Fabrikation der Wemst/ure, p. 22. 



CONTROL OF WORKING CONDITIONS 291 

The determinations are carried out as follows :— 

Calcium Tartrate.— 6 g. of substance are boiled with lo cc of 
potassium carbonate solution (500 g. per litre) and about 150 cc* of 
water for ten minutes, the solution made up to 200 cc. in a measuring 
flask, and filtered. 50 cc. of the filtrate are evaporated to about 15 cc 
and precipitated with 3 cc of glacial acetic acid and 100 cc of alcohol' 
The washed precipitate is then titrated with N/io potassium hydroxide 
to obtain the percentage of tartaric acid, using phenolphthalein as 
indicator. 

Tartaric Acid Liquors.-2o cc of the weak liquor (or 10 cc of 
concentrated liquors), freed from iron, are boiled with 40 cc' of 
potassium carbonate solution of the above concentration, the soluiion 
made up to 200 cc and filtered; 10 cc of the filtrate are then 
precipitated hot with 3 c.c of glacial acetic acid and 100 cc of alcohol 
The number of cubic centimetres of N/io alkali used in the titration! 
multiplied by 30 gives grams tartaric acid per litre. Phenolphthalein 
is used as the indicator. 

Old Liquors.-20 cc of the old liquor, freed from iron, are boiled 
with 60 ^;^- of potassium carbonate solution, made up to 200 cc. and 
filtered. Of the filtrate, 20 cc are precipitated with 5 cc of glacial 
acetic acid and 100 cc of alcohol. The number of cubic centimetres of 
^/o alkali used in the titration, multiplied by 15, gives the grams of 
tartaric acid per litre. 

^Vaste Products-Lees Residue and Gypsum.-3oo g of the 
sample are heated to boiling in a porcelain dish with 2c cc of 
concentrated hydrochloric acid and 500 cc of water, stirring well ' A 
part_ of the liquid is filtered, and 50 cc, without evaporation.' are 
precipitated with 3 cc of glacial acetic acid and 130 cc of alcohol 
Each 5 cc of A/ 10 alkali used in titration corresponds with approxi- 
mately o-i per cent, of tartaric acid in the residue 

Washings or "Runnings." (obtained from the precipitation of 
calcium tartrate).-200 cc of the runnings are evaporated to about 
50 cc, boiled for several minutes with 10 cc of potassium carbonate 
solution, and made up to 100 cc ; 60 cc of the filtrate are then mixed 
in a measuring cylinder with 10 cc of hydrochloric acid of sp gr i-io 
and made up with alcohol to a total volume of 180 cc The mixture is 
shaken and filtered immediately, and, without delay, to 150 cc of the 
filtrate is added successively 10 cc of potassium carbonate solution 
(500 g. per litre), 5 cc of glacial acetic acid and 100 cc of alcohol 
The mixture is well stirred, left till the following day, and the precipitate 
filtered off, washed, and titrated. 10 cc of N/io potassium hydroxide 
correspond with 1.50 g. of tartaric acid per litre. Phenolphthalein is 
used as the indicator in the titration. 

Free Sulphuric Acid in Tartaric Acid Liquors.-2o cc of the 



292 TARTARIC ACID 

liquor are made up to 200 c.c. with alcohol in a measuring flask, left to 
settle overnight, and filtered ; from 100 c.c of the filtrate the alcohol is 
completely evaporated on the water-bath, the residue diluted with 
water, and the sulphuric acid precipitated by barium chloride, and the 
precipitate collected and weighed as usual. 

For the approximate determination of the sulphuric acid it is 
sufficient to titrate 10 c.c. of the alcoholic solution with .\' 5 barium 
chloride solution until it ceases to produce a precipitate. 

Harmful Impurities (''Impurity Ratio")- — Alumina, iron, and 
phosphoric acid are determined in the same manner as in raw materials 
(p, 289) on the ash obtained from a known volume of the liquor (20-100 
c.c. according to the grade). 

The proportion of the ash which is soluble in water is often a useful 
guide in investigating works liquors, as well as the proportion of 
potassium carbonate present in this soluble extract. To estimate the 
potassium carbonate in the ash the quickest and best method is to add 
from 10-20 c.c. of 5 per cent, barium hydroxide solution to the ash, 
evaporate to dryness, ignite well, and then extract and filter. To the 
filtrate (and washings) 5 c.c of perchloric acid (sp. gr. 1-12) are added, 
and the liquid is evaporated until fumes of perchloric acid are given off 
strongly. The residue is taken up with 95-96 per cent, alcohol, the 
precipitate of potassium perchlorate collected on a Gooch crucible or 
Soxhlet tube, washed first with alcohol containing 0-2 per cent, of 
perchloric acid, finally with a little pure 95 per cent, alcohol, and 
weighed.! (W. A. D.) 

III. Finished Products. 

Tartaric Acid — Dextrorotatory tartaric acid is the only form made 
commercially. It is used as a mordant in dyeing and as a resist and 
discharge in printing ; also in medicine and photography and on a large 
scale in the manufacture of baking-powders, effervescent salines, fruit 
preserves, aerated waters, bon-bons, etc. The acid must be colourless, 
without smell, and, when crystalline, must consist of large, well-formed 
transparent crystals. A large quantity of tartaric acid, however, is used 
in the form of " smalls," that is, consisting of small crystals. Tartaric 
acid powder must not cake together and should not contain traces of 
free sulphuric acid, although a trace of sulphate (calcium sulphate) 
is riot prejudicial. Larger quantities of calcium sulphate, however, tend 
to make tartaric acid hygroscopic ; it is generally supposed that this is 
due to the action of tartaric acid on the sulphate giving rise to free 
sulphuric acid. 

As/i. — The limit for ash in tartaric acid crystal or powder used for 

' Cf. Section on " Potassium Salts," Vol. I., Part II., p. 530, and W. A. Davis, y. Agric. Set,, 
1912,5, 56. 



FINISHED PRODUCTS 293 

pharmaceutical purposes in Great Britain in past years has been 0-05 
per cent. The Committee of Reference to the Pharmacopoeia Com- 
mittee (1908) has, however, recommended that this limit should be 
raised to o-i per cent, as there is difficulty in obtaining tartaric acid 
with ash below 0-05 per cent. 

Arsenic is tested for by the following method recommended by the 
Royal Commission on arsenical poisoning (1903). From 1-5 g. of 
tartaric acid is used, with arsenic-free zinc and hydrochloric acid. The 
limit of arsenic adopted is y^^ gr. per lb. (1-4 parts AS2O3 per million, 
or 0-00014 per cent). There is no difficulty in obtaining tartaric acid 
in which arsenic falls considerably below this figure.^ 

Lead. — The limit of lead generally adopted in commerce in this 
country is 20 parts per million (0-002 per cent), as recommended by 
M'Fadden.2 Many methods have been suggested for making the test, 
of which the following are probably the most reliable. 

Method I. — Based on C. A. Hill's method,^ which is, like the following 
one, a modification of Warington's original colorimetric method.* 

A standard lead solution is prepared containing 5 parts of lead per 
million, by dissolving, pure metallic lead in a minimum quantity of 
nitric acid (equal parts of concentrated acid and water) and suitably 
diluting ; it is best to prepare a standard stock solution of lead, con- 
taining say I g. of lead per litre, and then, when required, to dilute this 
for use to the above concentration. The standard solution may also 
be prepared from pure lead nitrate or from crystalline lead acetate. 

For the test, 7 g. of the sample are weighed out, and a separate 
portion of 2 g. for the colorimetric comparison. Each portion is 
dissolved in about 10-15 c.c. of water, and to the 2 g. portion is added 
as many cubic centimetres of the standard lead solution as there are 
suspected to be parts per million of lead in the tartaric acid tested. 
Thus to compare with 15 parts of lead per million, 15 c.c. of the 
standard lead solution are used. To each solution is then added 
1-2 c.c. of 10 per cent, potassium cyanide solution and 13 c.c. of 
ammonia of sp. gr. o-88o, and the solutions are boiled for half a minute 
or longer so as to get both colourless if possible. They are next 
poured into two 50 c.c. Nessler cylinders of clear white glass and diluted 
to an equal volume (50 c.c), any difference of colour being corrected if 
necessary by the addition of a drop or two of a very dilute solution of 
caramel. To each solution is then added 1-2 drops of a freshly 
prepared colourless ammonium sulphide solution (obtained by saturating 
ammonia (sp. gr. o-88o), diluted with an equal volume of water, with 
hydrogen sulphide gas, carefully washed by passing through water). 

^ C^ A. W. M'Fadden, Local Government Board Report, Inspector of Foods, No. 2, 1907. 
'^ Cf. Tatlock and Thomson, Analyst, 1908, 33, 173 ; T. F. Harvey and J. M. Wilkie, Chem. 
and Drug., 1909, 75, 92. 

2 Chem, and Drug., 1905, 66, 388. * J. Soc. Chem. Ind., 1893, 12, 97. 



294 TARTARIC ACID 

The colour of the two solutions is compared by examining them, placed 
on a sheet of white paper, in a good light. 

Generally it is sufficient to make sure that the quantity of lead 
present is less than 20 parts per million, but if it is necessary to 
ascertain the exact quantity, comparisons are made with suitable pro- 
portions of lead (5, 10, 15, etc. c.c. of the dilute standard lead solution). 

Method II. — J. M. Wilkie's Method} — 7 g. of the sample are taken 
for the test, and 2 g. for the colorimetric comparison, to which the 
standard lead solution is added. Each is dissolved in about 35 c.c. of 
hot water, allowed to cool, a few drops of N\\o sodium thiosulphate 
solution added, and heated to incipient boiling, when the flame is 
removed. Any ferric iron present is rapidly reduced on cooling. 
When the solution is water-white, potassium cyanide (1-2 c.c. of 
10 per cent solution) is added, and then ammonia until the solution 
just smells of it (excess should be avoided). After diluting in Nessler 
cylinders, 2 drops of colourless ammonium sulphide solution are added, 
and the colorations compared as described above. 

In Germany, the following test, due to W. Klapproth, is used. 20 g. 
of the sample are ignited with 0-04 g. of calcium carbonate in a porcelain 
crucible. The small residue (which contains all the lead) is dissolved in 
a few drops of nitric acid, 2 or 3 drops of sulphuric acid added, and the 
mixture heated to expel the nitric acid. The residue, consisting of lead 
and calcium sulphates, is dissolved in ammonium acetate solution, and 
the solution filtered from insoluble matter (ferric oxide). 

To the clear solution hydrogen sulphide water is added, and the 
resulting brown coloration compared with that of a solution of 
ammonium acetate in water, containing a known quantity of lead to 
which hydrogen sulphide water has been added under similar conditions. 
To make certain that the brown coloration is due to lead and not to 
copper, some potassium cyanide solution is added, which destro)'S the 
brown colour due to copper, but has no effect on that due to lead. 

OtJicr Tests. — Quantities of 3 g. of the acid are dissolved in water, 
and submitted to the following tests. 

The solution of the pure acid should give no turbidity with barium 
chloride ; nor, after the addition of nitric acid, with silver nitrate. The 
solution rendered alkaline with ammonia should give no precipitate 
with ammonium oxalate. The acid should require for titration the 
calculated quantity of normal alkali, which has been standardised by 
pure potassium hydrogen tartrate, using phenolphthalein as indicator, 
under exactly the same conditions of concentration. 

Cream of Tartar. — This occurs in commerce in different grades of 
purity, containing varying proportions of calcium tartrate or calcium 
sulphate. The usual qualities are 95 per cent., 98 per cent., and 99-100 

* J. Soc. Chem. Ind., 1908, 28, 636 ; Harvey and Wilkie, Chem. and Drug., 1909, 75, 92. 



FINISHED PRODUCTS 295 

per cent. It is employed in dyeing as a mordant, for soupling silk, 
in food materials such as baking-powders, and in medicine. The 
tartaric acid and the contained calcium are determined. 

The total tartaric acid is best estimated by the Goldenberg method. 

The Acidity, on which the percentage of cream of tartar is generally 
gauged, is ascertained by titrating 5 g. of the sample with TV/i potassium 
hydroxide, which has been standardised by titration with 5 g. of pure 
recrystaliised 100 per cent, cream of tartar, dried at 100°, under 
exactly the same conditions of concentration, using phenolphthalein as 
indicator. The titration can also be made with 2 g. of the cream of 
tartar with iV/5 alkali, standarised under the same conditions as the 
actual test. This observance of exactly similar concentrations for 
standardisation and the actual test is necessary if exact results are to 
be obtained, owing to the hydrolysis of the neutral tartrate by water, 
which causes more alkali to be required (o- 1-0-3 c.c) in dilute solution 
than in concentrated solution. 

To estimate tartaric acid rapidly in cream of tartar, baking-powders, 
etc., F. W. Richardson and J. C. Gregory,^ and R. O. Brooks- have 
advocated a polarimetric method. 

The requirements as regards Arsenic and Lead 2.xq the same as for 
tartaric acid. 

Rochelle Salt (Sodium potassium tartrate) is employed in 
medicine, in silvering glass, and in electro-plating. The salt should 
dissolve in water to a clear solution, and the crystals also should be 
clear, where not rendered white on the surface by friction. The tests 
for purity are the same as for tartaric acid. 

Tartar Emetic (Antimony! potassium tartrate). — This is used as a 
fixative for tannin mordants in dyeing, and to a limited extent in 
medicine. For analysis, the salt is dissolved in 300 parts of warm water, 
the antimony precipitated by hydrogen sulphide, finally with addition 
of a little hydrochloric acid, and the liquid, separated by filtration from 
the antimony sulphide, used for the estimation of the tartaric acid. The 
antimony content is controlled by titration with iodine solution by 
Mohr's method (see the section on "Metals other than Iron," Vol. II., 
Part I., p. 282). 

Neutral Potassium Tartrate, Borax Tartar, and Iron Tartrate 
find some application in medicine. 

Literature. 

Carles, P. — Les Derives Taririques dit Vz'n, 3rd edition, 1903. 
ClAPETTl, G. — Llndustria Tartarica, published by Hoepli, Milan, 1907. 
Rasch, H. — Die Fabrikation der Weinsdure, 1897. 

ROUX, U. — La Grande Industrie des Acides Organiques, Bitartrate de Potasse, 
Acide Tartrique, Acide Citrique, 191 2. 

^ J. Soc, Chem. Ind., 1903, 22, 405. ^ y_ Amer, Chem. Soc, 1904, 26, 813. 



CITRIC ACID 

By WiLHELM Klapproth, Dr Ing., Chemist to Messrs C. H. Boehringer, Nieder- 
Ingelheim, on Rhine. English translation revised by W. A. Davis, B.Sc, 
Rothamsted Experimental Station. 

I. Raw Materials. 

Citric acid is obtained from the juice of fruits of several species of 
Citrus. Besides the juice of the lemon [Citrus inedica), that of the 
Bergamot {Citrus Bergamid) and of several West Indian species of 
Citrus, especially the Lime {Citrus Linionuvi) are also worked. Small 
quantities of citric acid were obtained experimentally some years back 
by the fermentation of sugar by the organism discovered by C. Wehmer.^ 

The lemon juice is in general prepared at the place of production, 
by pressing the fruit, and is then subjected to a short fermentation to 
remove protein matter. The juice cleared in this way contains from 
45-75 &• of citric acid per litre, and either comes direct into commerce^ 
or is further concentrated by boiling in open copper vessels. The price 
for the juice per "pipe" is calculated on the basis of 64 oz. citric acid 
per Imperial gallon. As i pipe =108 Imperial gallons or 490 litres 
(1 gallon = 4-536 litres), and i oz. = 28-35 g., the "pipe" of juice of the 
above concentration contains 196 kg. of citric acid. Market prices are 
referred to this unit. The concentrated bergamot juice is mostly sold 
on the basis of 48 oz. per Imperial gallon. For factory purposes it is 
often more useful to express the concentrations in grams per litre ; the 
above strengths of 64 and 48 oz. per gallon then become 400 g. and 
300 g. of citric acid per litre. 

Formerly such juice served exclusively as the raw material in the 
manufacture of citric acid. Now, however, most of the juice is con- 
verted into calcium citrate at the place of production, and this is to-day 
the principal raw material. Raw lime juice is, however, still an 
important article. 

All analyses are expressed in terms of the tribasic citric acid with 
I mol. of water of crystallisation, i.e., C^HgO^+HoO, the molecular 
weight of which = 2 10. 

' Beitti'ige zur Kenntnis einhewiischer Pihe, !., 1893 ; P'abriques de produits chimiques de Thairn 
et Mulhouse, Ger. Pat. 72957, 1893 ; Eng. Pat., 5620, 1893,/. Sec. Ckem. Ivd., 1894, 13, 275. 

296 



RAW MATERIALS 297 

The composition and complete analysis of raw juices have been 
studied by R. Warington ^ and more recently by K. Farnsteiner.^ 

The dark brown, concentrated juice was formerly valued either on 
its specific gravity, or on its acidity as determined by simple titration. 
Adulteration by salts (evaporated sea-water) and acids {e.g. sulphuric 
acid) was therefore common. The present method of analysis used in 
commerce was introduced by Warington, and is based on the insolubility 
of calcium citrate. It must be remembered, however, that calcium 
citrate is insoluble only in Jiot water, whilst it is not precipitated from a 
cold solution and even redissolves to a considerable extent in cold water. 

Warington's method is now generally carried out as follows in this 
country and in Sicily (Ogston and Moore). 

Calcium Citrate. 

4 g. of the citrate is boiled with 30 c.c. of 2 A^-hydrochloric acid in a 
100 c.c. standard measuring flask for ten minutes, the solution being 
then cooled and made up to the mark with water. It is then shaken 
and filtered through a dry filter paper, 50 c.c. of the filtrate being 
measured by a standard pipette into a beaker of 300 c.c. capacity, and 
exactly neutralised with dilute sodium hydroxide free from carbonate, 
using phenolphthalein as indicator. The solution is next made slightly 
acid by the addition of 3 or 4 drops of TV-hydrochloric acid, 2 c.c. of 
a 45 per cent, solution of calcium chloride added, the liquid raised to 
the boil and kept boiling for fifteen minutes ; to avoid bumping it is 
necessary to stir the liquid well until actually boiling, after which it can 
safely be left. The hot liquid is filtered and the precipitate on the 
filter paper washed with boiling water six times. The filtrate and 
washings are then made just alkaline by adding a drop or two of dilute 
ammonia, and boiled down to about 15 c.c. The precipitate which 
forms is collected on a small filter paper and washed with boiling water 
six times, using a very small quantity of water for each washing. The 
filtrate and washings are treated with a drop of ammonia, if they have 
become acid, and are boiled down to about 10 c.c, but as a rule no 
further precipitate will be obtained whilst the liquid is hot ; any 
precipitate which forms on cooling can be neglected. 

The filter papers with their precipitates are dried at 100° and 
burnt together in a platinum dish with a cover. The flame should be 
kept low until the whole is charred, and then gradually raised until the 
ash is white. It is then carefully treated with 30 c.c. of A'-hydrochloric 
acid, the whole boiled until all is dissolved and all carbon dioxide 
expelled, and the resulting solution titrated back with A75 or Njz 
sodium hydroxide, using phenolphthalein as indicator. 

The sodium hydroxide is standardised by pure potassium hydrogen 

^ J. Chem. Soc, 1875, 28, 925. ^ ^^ [Jnters. Nahr, u. Genussm., 1903, 6, I. 



298 CITRIC ACID 

tartrate, and the TV/ 1 hydrochloric acid by the alkali; phenolphthalein 
is used as indicator. 

The number of cubic centimetres of iV/i HCl used for the neutralisa- 
tion of the ash x 0-070 gives the weight of citric acid in the portion 
tested. 

An almost identical method has been described by L. and J. Gadais.^ 
If the citrate contains much sulphate it is advisable to ash at as 
low a temperature as possible, preferably with an alcohol flame. Before 
dissolving in hydrochloric acid, the ash should be treated with 10 c.c. 
of hydrogen peroxide. [If, as is usual, the hydrogen peroxide contains 
free acid, allowance must of course be made for it.] 

Lime Juice, Lemon Juice, and Factory Citric Acid Liquors, 

The analysis of these materials is conducted as follows : — From 
15-20 c.c. of unconcentrated juice, or an amount corresponding with 
3 c.c. of concentrated juice (40 g. per 100 c.c), previously diluted to 
facilitate exact measurement, are exactly neutralised with pure 
potassium hydroxide (iV/S). The liquid, having a volume of about 
50 c.c, is heated to boiling, mixed with a slight excess of concentrated 
calcium chloride solution, and kept at a gentle boil for half an hour. 
The precipitate is filtered off immediately while hot, washed with 
boiling water six times, and the mother liquor and washings again 
evaporated and worked up as described above under calcium citrate. 
The whole of the calcium citrate collected is then dissolved in 30 c.c. 
of iV/i hydrochloric acid and the excess of acid estimated as above. 
In dealing with the cruder factory liquors three or four evaporations 
are generally necessary to separate all the calcium citrate. 

The above methods are not entirely free from error,^ but have not 
yet been replaced by better. Incorrect results are obtained when the 
calcium citrate or juice contains other acids which yield sparingly 
soluble calcium salts. The presence of oxalic acid or of tartaric acid 
may be detected by the fact that the cold, neutralised solution gives a 
precipitate in the cold with calcium chloride. 

C. Ulpiani and A. Parozzani '■'' have described a method of analysis 
which, according to Klapproth, gives satisfactory results for citric acid 
even in presence of other organic acids. This method depends upon 
the fact that citric acid, in presence of a sufficient quantity of calcium 
chloride, is precipitated by sodium hydroxide in the cold when the whole 
of the acid is saturated, and in the hot solution when one-third of the 
acid is saturated. M. Spica* has described a method which consists in 
measuring the carbon monoxide which is evolved on gently warming 

' Bull. Soc. Chun., 1 909 [iv.], 5, 287. ^ Qy q, von Spindler, Chem. Zeit., 1903, 27, 1263. 

^ Atti. R. Accad, Lined, 1906 [v.], 15, ii., 517. 

* Chem. Zeit., 1910, 34, 1141 ; cf. Barboni, Ann. Lah, Cenlr. deUe GabelU, 1912, p. 311. 



RAW MATERIALS 299 

the sample with concentrated sulphuric acid. Neither of these methods 
has been adopted in commerce. 

The presence of sulphuric acid, which can give rise to error owing 
to the reduction of calcium sulphate to sulphide during ignition, may be 
recognised in the juice or liquors, after adding hydrochloric acid, by 
means of barium chloride. If only small quantities of sulphuric acid 
or sulphates are present, the above methods can be used ; in presence 
of larger quantities, however, the use of hydrogen peroxide (see above) 
is necessary, or the following method proposed by J. Creuse ^ may be 
used : — 

20 c.c. of the unconcentrated or 3 c.c. of the concentrated juice or 
liquor is accurately neutralised with pure (about iV/5) potassium 
hydroxide and then evaporated to dryness on the water-bath. The 
residue is taken up with from 20-30 .c.c. of 63 per cent, alcohol, and the 
potassium citrate filtered from the undissolved salts (potassium sulphate, 
etc.), the residue being washed with a little 93 per cent, alcohol. To 
the solution, which, if necessary, is neutralised with a drop of dilute 
acetic acid or ammonia, a neutral alcoholic solution of barium acetate is 
added and double the volume of 95 per cent, alcohol, the mixture 
vigorously stirred and left to the following day. The barium citrate 
precipitate, (CgH507)2Ba3, is then filtered off and washed with 6^ per 
cent, alcohol; the barium is estimated in the precipitate, after ignition, 
either by precipitation as barium sulphate or by dissolving it in 
iV/5 hydrochloric acid and titrating back the excess of acid with alkali. 
As the precipitation of barium citrate presents certain difficulties, it 
is preferable, after the removal of the potassium sulphate by alcohol, to 
evaporate the latter, take up with a little water and precipitate with 
calcium chloride, subsequently igniting the calcium citrate and dissolving 
it in 30 c.c. of N/i hydrochloric acid as in Warington's method. (W. 
A. D.) 

To estimate Free lime or Calcium carbonate in calcium citrate, 5 g. of 
the sample is dissolved in a known quantity of standard hydrochloric 
acid (A^/i or A^/2), kept gently boiling, and when cold the solution is 
titrated back with alkali hydroxide in the usual manner. Each cubic 
centimetre of normal acid neutralised by the sample corresponds with 
0-050 g. CaCOg in the portion taken. 

II. Control of Working Conditions. 

Although phosphoric acid, alumina, and iron are more readily 
removed from citric acid than from tartaric acid liquors, it is necessary, 
in order to avoid losses of citric acid, to see that the auxiliary materials 
as well as raw material are as free as possible from these substances. 

1 Chem. News^ 1872, 26, 50. 



300 CITRIC ACID 

The "impurity ratio" is determined as in the case of tartaric acid 
(see p. 289). Chalk and lime must be free from magnesia in treating 
juice, etc., otherwise not only is there loss of citric acid in the precipita- 
tion of the calcium citrate, but the citric acid liquors obtained from the 
latter will contain magnesium sulphate, which leads to subsequent loss. 
Citric acid in the liquors is estimated by the methods given under I. 
Free sulphuric acid is estimated as in tartaric acid liquors (p. 291). 

III. Final Products. 

Citric acid is used in dyeing and textile printing, and very largely 
for consumption in effervescent salines, lemonades, fruit essences, 
marmalades, bonbons, etc. On account of its pleasant, acid taste, it is 
particularly useful for the latter purposes, and it is also used in cake 
making. It is employed in medicine as a preventive of scurvy, 
gout, etc. 

In view of differences in the amount of water of crystallisation 
contained by the acid, a titration of the acid is a useful test. 

To detect and estimate Oxalic Acid the insolubility of calcium 
oxalate in cold solution is utilised ; calcium citrate is not precipitated in 
the cold. 

To separate and estimate Tartaric Acid the insolubility of potassium 
hydrogen tartrate in alcohol is made use of, as in the Goldenberg 
method. (See p. 287.) 

For detecting small quantities of tartaric acid in citric acid O. von 
Spindler utilises a colour reaction which is shown on precipitating. 
citric acid solutions containing tartaric acid with a hot solution of 
mercuric oxysulphate mixed with potassium bichromate (Denige's test). 

A test proposed by P. Pusch consists in heating the acid with 
sulphuric acid for thirty seconds ; J. R. Will ^ has prepared a Table 
showing the different colorations produced by differing proportions of 
tartaric acid. 

Lead, Arsenic, and As/i are tested for as under tartaric acid, the limit- 
ing quantities allowed being the same as in the case of tartaric acid. (See 
p. 293.) It is usual, however, in commerce to require a higher degree 
of freedom from lead than in the case of tartaric acid ; the amount 
present seldom exceeds 10 parts per million. Arsenic is generally 
entirely absent. 

Literature. 

Hallerb.\CH, W. — Die Citronensiiure unci thre Derivate, 191 1. 

ROUX, \2.—La Grande Industrie des Acides Organiques, Bitartrate de Potasse, Acide 
Tartrique, Acide Citrique, 191 2. 



' Chem. Zeit., 1904, 28, 1 5, I48. 



ORGANIC PREPARATIONS 

By J. Messner, Ph.D., Messrs E. Merck & Co., Darmstadt. English translation 
revised by CHARLES A. Keane, D.Sc, Ph.D. 

Acetaldehyde. 

CH3 . COH. Molec. wt. 44-03. 

Acetaldehyde is a colourless, mobile, inflammable liquid. Sp. gr. 0-79; 
boiling point 2i°-22°. The purest commercial product (aldehyde absolu- 
tus) contains 95-98 per cent, of aldehyde, " aldehyde concentratissimus " 
about 80 per cent, and " aldehyde concentratus " about 60 per cent. 

Acetaldehyde is miscible with water, alcohol, and ether in all 
proportions ; also with ammonia when a considerable evolution of heat 
occurs. A yellowish-brown opalescence is produced on the addition of 
sodium hydroxide ; ammoniacal silver solution is reduced on warming. 
An intense blue coloration is produced on adding a few drops of 
acetaldehyde to 10 c.c. of sodium nitroprusside solution mixed with 
2-3 drops of piperidine ; formaldehyde does not give this reaction.^ 

Tests for Impurities. 

Inorganic Matter. — 50 c.c. of the aldehyde should not leave more 
than 5 mg. of residue upon evaporation on the water-bath. 

Metals. — Aldehyde should be neither coloured nor rendered turbid 
by sulphuretted hydrogen water or by the subsequent addition of 
ammonia till alkaline. 

Hydrochloric acid. Chlorides. — No immediate change should take 
place on addition of silver nitrate solution. 

Acetic Acid. — On addition of 2 c.c. of N\i sodium hydroxide solution 
to 20 c.c. of aldehyde in 100 c.c. of water, the solution should be coloured 
red on addition of phenolphthalein. A good sample of aldehyde should 
not contain more than 06 g. of acetic acid in 100 c.c. 

Quantitative Estimation. 
The following method of estimation is due to R. Bourcart.^ The 

^ For colour reactions of aldehyde see Z. anal. Chem.^ 1893, 32, 347 ; 1898, 37, 47 ; also 
Merck's Reagenzien-Verzeichniss, 1908, p. 289. 

- Bull. Soc. Ind. Mulkouse, 1889, 59, 558 ; /. Soc. Chem. hid., 1 890, 9, 557. 
301 



302 ORGANIC PREPARATIONS 

following solutions are prepared: — Potassium bichromate i:ioo; 
sulphuric acid lo per cent, by volume ; potassium iodide i : lo ; starch 
solution, and sodium thiosulphate solution of such a strength that i c.c. 
exactly corresponds to i c.c. of the above bichromate solution when 
titrated against it. 

To carry out the determination lo c.c. of the sample is made up to 
I litre with water, and lo c.c. of the aldehyde solution placed in a well- 
fitted 100-125 c.c. pressure flask. To this solution 50 c.c. of the 
bichromate solution and 20 c.c. of the sulphuric acid are added, the 
flask closed and heated for three hours in a boiling water-bath. 
After cooling, the contents of the flask are washed out into a beaker, 
and sufficient potassium iodide solution added to produce a clear, brown 
solution, which is then titrated back with the thiosulphate. By the 
oxidation of aldehyde by means of chromic acid acetic acid is formed, 
I mol. of aldehyde requiring ^ of a molecule of bichromate, or 
I mol. of bichromate oxidises 3 mols. of aldehyde. i c.c. of 
bichromate used up corresponds, therefore, to 0-004485 g. of aldehyde. 
In order to arrive at the percentage content of the aldehyde under 
examination, the number of cubic centimetres of bichromate solution 
used up is multiplied by 4485, provided that the above quantities 
have been worked with. 

This method is not applicable if the aldehyde contains alcohol, which 
is always the case with the poorer qualities. The following method is 
then preferable: — A 125 c.c. pressure flask is taken, in which are placed 
30 c.c. of water, 20 c.c. of ammonia (sp. gr. 0-91), 25 c.c. of Nji silver, 
nitrate solution, and 25 c.c. of a freshly made solution of 2 c.c. of aldehyde 
in 100 c.c. of water. After closing the flask securely, it is heated for 
about eight hours in a boiling water-bath, allowed to cool, and the product 
of the reaction washed out into a 250 c.c. measuring flask which is 
finally filled up to the mark with water. After shaking well, the 
contents of the flask are allowed to settle, and 50 c.c. of the clear 
solution titrated with Nj 10 ammonium thiocyanate solution after 
acidifying with nitric acid and the addition of some iron alum solution 
as indicator. The quantity of silver solution decomposed by the 
aldehyde is thus determined, i c.c. Nji silver nitrate solution corre- 
sponds to 0-022016 g. aldehyde. 

The following method of analysis, due to A. Seyewetz and J. Bardin,^ 
is applicable in the presence of alcohol, acetal, and paraldehyde. A 
few drops of phenolphthalein solution are added to a 10 per cent, 
solution of anhydrous sodium sulphite, which is then neutralised with 
sulphuric acid. To 40 c.c. of the neutral solution, which is cooled to 
4° or 5", 10 c.c. of a solution of acetaldehyde diluted to 7-8 per cent. 
is added, and the solution titrated with Nji sulphuric acid till colour- 

1 Bull. Soc. Chim.^ 1905 [iii.], 33, icoo ; J. Soc. C/iem, Ind., 1906, 25, 202. 



ACETANILIDE 303 

less. The content of aldehyde is calculated fronn the quantity of acid 
required for the titration according to the equation : — 

2Na.S03+H.3SO, + 2CH3COH = (xXaHSOg+CH^. COH)2+Na,SO,. 

The following method is especially recommended : — About 20 c.c. 
of well-cooled water are placed in a 100 c.c. measuring flask, the 
whole tared on the balance and about 5 g. of acetaldehyde (accurately 
weighed) added. The flask is filled up to the mark with water, 
shaken, and 10 c.c. of the mixture transferred to a 500 c.c. stoppered 
flask containing about 350 c.c. of water and 30 c.c, ofiV/i potassium 
hydroxide solution. After the addition of 10 c.c. of a 30 per cent, 
hydrogen peroxide solution (perhydrol) and thoroughly well shaking, 
the contents of the flask are allowed to stand overnight and then 
titrated with Nji hydrochloric acid, using phenolphthalein as indicator. 
In addition, the acidity of the acetaldehyde must be determined and 
allowed for. For this purpose 10 g, of acetaldehyde are run into 50 
c.c. of water and titrated with Nji potassium hydroxide, i c.c. of 
potassium hydroxide corresponds to 0-04403 g. of acetaldehyde. 

Acetanilide. 

CgHs . NH . COCH3. Molec. wt. 135-08. 

Acetanilide crystallises in colourless glistening plates which dissolve 
in 230 parts of cold and in about 22 parts of boiling water, in 3-5 parts 
of alcohol, and readily in ether and chloroform ; all the solutions have a 
neutral reaction. It has no smell and a slight burning taste. Acetani- 
lide melts at 11 3''-! 14° and boils at 295^ 

When heated with potassium hydroxide and a few drops of chloro- 
form, acetanilide immediately gives the smell of isonitrile. When o-i g. 
of acetanilide are gently boiled for about half a minute with 2 c.c. of 
hydrochloric acid and 2 c.c. of a 5 per cent, aqueous solution of phenol, 
and sufficient calcium hypochlorite solution added, a reddish -violet 
turbidity is produced which changes to an indigo-blue solution on the 
addition of excess of ammonia.^ 

Tests for Impurities. 

Inorganic Matter. — i g. of acetanilide should, on heating, not leave 
more than 0-5 mg. of residue. 

Foreign Organic Matter. — o-2 g. of acetanilide should dissolve to a 
colourless solution on shaking with 2 c.c. of sulphuric acid. This solu- 
tion should not turn yellow on the addition of nitric acid (Phenacetine), 

^ For other identifying reactions for acetanilide, cf. Z, aiial. C/iem., 1888, 27, 666 ; 1889, 
28, 103, 354, 709, 711 ; Pharm. Zentralb.^ 30, 241, 603 ; 32, 41 ; Pharm, Zeit., 1898, p. 546 ; 
Merck's Reag.-Verz.^ 1908, p. 289, 



304 ORGANIC PREPARATIONS 

The cold, saturated, aqueous solution of acetanilide should not be 
coloured by the addition of ferric chloride solution (aniline salts give a 
dirty green, antipyrine a red, salipyrine a violet, and thalline a green 
coloration). 

Free Aui/ine, Dust, Resinous Matter, and Acet-toltdde ma}- be 
recognised in the following manner: — A boiling solution of i g. of 
acetanilide in 30 c.c. of water, to which is added a drop of potassium 
permanganate solution (i : 1000), should retain the rose coloration for at 
least five minutes, and on again boiling should not become either 
discoloured or cloudy. The commercial product cannot ahva\s be 
expected to comply to this stringent test. It is important that the glass 
vessel used for the test be scrupulously clean. 

Free Acetic Acid. — The cold, saturated, aqueous solution of acetanilide 
should not redden blue litmus paper.^ 

Acetic Acid. 

CH3 . COOH. Molec. wt. 60-03. 

Pure acetic acid comes into commerce of various strengths. 

The 95-99 per cent, acid (glacial acetic acid) is a colourless liquid, 
with a suffocating acid smell, miscible in all proportions with water, 
alcohol, and ether. It has a sp, gr. of from i-o66-i-05S at 15°; it 
should not solidify above 9°-5, and should boil at 110-117^ The 
completely anhydrous acid boils at 118" and has a sp. gr. of 1-0553 ^^ 

Tests for Impurities. 

Inorganic Matter and non-volatile Organic Matter. — No appreciable 
residue should remain on evaporation of 10 c.c. of acetic acid. 

Metals arid Alkaline Earths. — 20 c.c. of acetic acid, diluted with 100 
c.c. of water, should show no brown coloration with sulphuretted 
hydrogen water. 10 c.c. of acetic acid, diluted with 100 c.c. of water, 
should remain unaltered on the addition of excess of ammonia, and 
also on allowing to stand in a warm place for some time after the 
addition of ammonium sulphide and of ammonium oxalate solution. 

Arsenic. — 2 c.c. of acetic acid to which is added 6 c.c. of stannous 
chloride solution should show no coloration on standing for an hour. 

The Pharmacopoeia Committee of the General Medical Council 
recommend the Gutzeit test as a limit-test for arsenic in acetic acid 
and other official substances. A special apparatus is described for 

1 For the testing and valuation of acetanilide, c/. E. Ritsert, Pharm. Zeit., 1890, 35, 306 ; /. 
Soc. Chem. Ind., 1890, 9, 1068. 

For the determination of acetanilide in pharmaceutical preparations, see J. L. Turner, and 
C. E. V'anderklud, Pharm. J., 1907, p. 521 ; / Soc. Chem. Ind., 1907, 26. 4S6 ; also A. Seidell, 
J. Amer. Chem. Soc, 1907, 29, I088 ; J. Soc. Chem. Ind,, 1907, 26, 9S9 



ACETIC ACID 305 

carrying out the test and filter paper soaked in a saturated solution of 
mercuric chloride is used as the test-paper. The limit, in the case of 
acetic acid, is placed at 2 parts of arsenic per 1,000,000.^ The Gutzeit 
test is described in the section on " Sulphuric Acid," Vol. I., Part I., 

P- 374- 

Sulphuric Acid. — A solution of 10 c.c. of acetic acid in 150 c.c. of 
water heated to boiling, to which barium chloride solution is added, 
should show no formation of barium sulphate even on standing for 
several (fifteen) hours. 

HydrocJiloric Acid. — A solution of 5 c.c. of acetic acid in 50 c.c. of 
water should give no precipitate or opalescence on acidifying with 5 c.c, 
of nitric acid and adding silver nitrate solution. 

Empyreuinatic impurities and Sulphurous Acid. — 0-3 c.c. of A^/io 
potassium permanganate solution should not be discoloured within a 
quarter of an hour by 5 c.c. of acetic acid diluted with 15 c.c. of water. 
A freshly made mixture of acetic acid and sulphuretted hydrogen water 
should remain clear. 

Formic Acid. — If a mixture of i g. of acetic acid, i g. of sodium 
acetate, 10 c.c. of water, and 5 c.c. of mercuric chloride solution be heated 
for half an hour in a boiling water-bath, there should be no separation 
of mercurous chloride. Formic acid may be quantitatively estimated 
by the following method : — 5 c.c. of the acetic acid are added to a solution 
of 5 g. of sodium acetate in 30 c.c. of water ; 40 c.c. of mercuric chloride 
solution (5 per cent.) are then added and the mixture heated for two 
hours in a steam-bath, using a reflux condenser. The separated 
mercurous chloride is collected in a Gooch crucible, washed with hot 
water, dried and weighed. The weight found multiplied by 0-097726 
gives the quantity of formic acid. - 

Acetic acid used for technical purposes, e.g. in the colour industry, 
need comply to but a few requirements, and the foregoing tests may 
therefore be correspondingly relaxed. {^Cf. section on " Organic 
Dyes," Vol. II., Fart II., p. 896.) 

Quantitative Estimation. 

1. By Titration. — The dilute aqueous solution of the acid is titrated 
with N\\ potassium hydroxide, using phenolphthalein as indicator. 
I c.c. of N\\ potassium hydroxide corresponds to 0-06003 g- of acetic 
acid. 

2. A gas-volumetric method of estimation has been proposed by H. 
Kux,3 

3. By the specific gravity as given in the subjoined Table prepared 
by A. Oudemans. On mixing concentrated acetic acid with water, a 

' Chem. and Drug., 1912, 81, 122. ^ Cf. Apoth. Zeit., 1910, p. 727. 

^ Z, anal. Chem., 1893, 32, 138. 

Ill u 



306 



ORGANIC PREPARATIONS 



contraction in volume takes place -Aith a corresponding rise in specific 
gravity, the latter attaining a maximum at a point corresponding to the 
formation of the hydrate, C^H^O.^+HoO or ortho-acetic acid 
[CH3. C(0H)3]. This hydrate contains yj per cent, of acid, and 
has a sp. gr. of 10748. On further dilution the specific gravity 
diminishes, so that a 51 per cent, acid has the same specific gravity as 
an acid of 97 percent. Specific gravities above 10553 may therefore 
indicate acids of different strengths. In determining the strength of an 
acid by this method, the specific gravity is taken, and if it proves to 
be over 1-0553 the acid is diluted with not too much water. If on 
dilution the specific gravity rises, the acid is stronger than TJ per cent. ; if 
the specific gravity diminishes, the acid is weaker than 'j'j per cent. 



Table 39. 
Specific Gravities of Acetic Acid at 15 (Oudemans). 



Sp. gr. 


Per cent. 


Sp. gr. 


Per cent. 


Sp. gr. 


Per cent. 


Sp. gr. 


Per cent. 


1 -0007 


1 


' 1-0363 


26 


1-0623 


51 


1-0747 


76 


1 -0022 


2 


1-0375 


27 


1 0631 


52 


10748 


77 


1 -00:^.7 


3 


1-0388 


28 


1-0638 


53 


1-0748 


78 


1 •oo:.2 


4 


1-0400 


29 


1-0646 


54 


1-0748 


79 


1-0067 


5 


1-0412 


30 


1-0653 


55 


1-0748 


80 


1-0083 


6 


1-0424 


31 


1-0660 


56 


1-0747 


81 


1-0098 


7 


1-0436 


32 


1-0666 


57 


1-0746 


82 


1-0113 


8 


1-0447 


33 


1 -0673 


58 


1-0744 


83 


1-0127 


9 


1-0459 


34 


10679 


59 


1-0742 


84 


1-0142 


10 


1-0470 


35 


1-0685 


60 


1-0739 


85 


1-0157 


11 


1-0481 


36 


1-0691 


61 


1-0736 


86 


1-0171 


1-? 


1-0492 


37 


1-0697 


62 


1-0731 


87 


1 0185 


13 


1 -0502 


88 


1-0702 


63 


1-07-26 


88 


1-0200 


14 


1 1-0513 


39 


1-0707 


64 


1 -0720 


89 


1-0214 


15 


1 -0523 


40 


1-0712 


65 


1-0713 


90 


1-02-28 


16 


1-0533 


41 


1-0717 


66 


1-0705 


91 


1-0242 


17 


1-0543 


42 


1-0721 


67 


1 -0696 


92 


1-0256 


18 


1-0552 


43 


1-0725 


68 


1 -0686 


93 


1-0-270 


19 


1 -0562 


44 


1-0729 


69 


1-0674 


94 


1-0284 


20 


1-0571 


45 


1-0733 


70 


1 -0660 


95 


1-0298 


21 


1-0580 


46 


1 -0737 


71 


1-0644 


96 


1-0311 


22 


1-0589 


47 


1-0740 


72 


1 -0625 


97 


1 -0324 


23 


1 -0598 


48 


1-0742 


73 


1-0604 


98 


1-0337 


24 


1-0607 


49 


1-0744 


74 


1-058T 


99 


1-0350 


25 


1-0615 


50 


1-0746 


75 


1-0553 


100 



Calcium Acetate. — The most important raw material in the 
manufacture of acetic acid is crude calcium acetate, which comes into 
the market as a grey to brown mass more or less contaminated with 
calcium carbonate and cmpyreumatic and decomposed organic matter. 
For its valuation, a determination of the content of pure calcium acetate 
or of acetic acid suffices. As a matter of practice the valuation may be 
limited to the estimation of the latter, by distillation with phosphoric 



ACETIC ACID 307 

acid, according to the method given by R. Fresenius,^ which is carried 
out as follows : — 

A tubulated retort of suitable size, with its neck bent at an obtuse 
angle, is fitted air-tight to a Liebig's condenser. Into the retort is 
placed 5 g. of the calcium acetate to be tested, 50 c.c. of water, and 
50 c.c. of phosphoric acid (free from volatile acids) of sp. gr. i-2; 
the mixture is then heated on a sand-bath until all volatile products 
have distilled over, i.e. to dryness, and the distillate very carefully 
transferred to a 250 c.c. measuring flask. When the contents of the 
retort have cooled, 50 c.c. of water are added and a second distillation 
to dryness carried out. The same operation is repeated a third time, 
and finally the total distillate is made up to 250 c.c, and 50 c.c. of the 
solution titrated with A^/i sodium hydroxide, using phenolphthalein as 
indicator, i c.c. Nl\ sodium hydroxide corresponds to 006003 g. of 
acetic acid or 007907 g. of calcium acetate. The number of cubic 
centimetres of sodium hydroxide used multiplied by 6-003 gives 
the percentage content of acetic acid (CH^.COOH), and multiplied 
by 7-907, the percentage content of anhydrous calcium acetate 
[Ca(C.,H30,U 

The triple distillation as given above may be dispensed with by 
somewhat modifying the procedure as follows : — The tubulated retort is 
connected up with a suitable steam supply, which may be readily 
connected and disconnected and the steam led into the bottom of the 
retort by means of a bent glass tube. As soon as the bulk of the 
volatile matter has come over on the sand-bath, steam is allowed to 
blow in through the thick residue, at the same time reducing the 
heat of the sand-bath. F'or the distillation by steam a 500 c.c. 
measuring flask is used as receiver. The distillation is stopped as 
soon as the distillate ceases to be acid. The receiver is then filled 
up to the mark with water and the contents well mixed by shaking. 
When working on 5 g. of the crude acetate and using the data for 
calculation given above, 100 c.c. of the acetic acid solution obtained by 
distillation is titrated. 

In this method of estimating acetic acid, small quantities of 
homologous acids (propionic, butyric, etc.) contained in the calcium 
acetate are determined along with the acetic acid and calculated as 
such. This source of error is generally a matter of little importance in 
technical work, but should it be desired to take these acids into account, 
the method given by E. Luck ^ is recommended, which is based on the 

^ Z. anal. Chem., 1866, 5, 315 ; 1875, 14, 172. Cf. also W. Fresenius and L. Griinhut, ihid., 
1908, 47, 597 ; /. Soc. Chem. hid., 1908, 27, 1012 ; J. Jedlicka, ibid., 1910, 49, 97 ; J. Soc. Cliem. 
Ind., 1910, 29, 421 ; and T. S. Gladding, J. Ind. and Eng. Chem., 1909, I, 250 ; J. Soc. Chem. 
Ind., 1909, 28, 467. 

- Z, anal. Chem., 1871, 10, 184 ; cf. also Pharm, Zeit., 1910, p. 810. 



308 ORGANIC PREPARATIONS 

different solubilities of the barium salts of these homologous acids in 
absolute alcohol. 

To carry out this method the distillate obtained in the manner 
previously given is neutralised with barium h\droxide, evaporated to 
dryness, and well boiled with Soo c.c. of absolute alcohol. The alcoholic 
solution, which contains the barium salts of the homologous acids and 
0-0284 g. of barium acetate per 100 c.c, is cooled and filtered, the 
alcohol evaporated off, the residue taken up with water, the barium 
precipitated with sulphuric acid, and the barium sulphate weighed. 
From the weight of the latter, 0-2085 S- nriust be subtracted to allow 
for the barium acetate (as barium sulphate) dissolved by the 800 c.c. 
of alcohol, and the remaining barium sulphate calculated to calcium 
acetate (i g. barium sulphate = 0-6774 g. calcium acetate). The 
quantity of calcium acetate thus found is deducted from the amount 
found by titration. 

If the calcium acetate to be examined contains appreciable quantities 
of calcium chloride, the distillate obtained by the foregoing methods 
will contain hydrochloric acid. A portion of the distillate is therefore 
tested for chloride by adding nitric acid and silver nitrate solution. 
If only an opalescence is produced, the trace of hydrochloric acid 
may be neglected, but if a precipitate of silver chloride be formed, 
the hydrochloric acid xnust be estimated either volumetrically with A71 
silver nitrate solution or by weighing the precipitate of silver chloride, 
and the quantity found allowed for. 

Acetone.^ 

CH3 . CO . CH3. Molec. wt. 58-05. 

Acetone is a colourless, mobile, neutral liquid, readily inflammable, 
burning with a luminous non-smoky flame. It has a peculiar, not 
unpleasant smell and a camphor-like taste. Acetone boils at 55-56"', 
and has a sp. gr. of 0-798. It is miscible with water, alcohol, ether, 
chloroform, and oils in all proportions. When 10 c.c. of acetone are 
mixed with 10 c.c. of ammonia, which should produce no warming 
of the solution (aldehyde), then 10 c.c. of N/i iodine solution added 
and the mixture diluted with 60 c.c. of water, a cloudiness due to the 
formation of iodoform is produced.^ 

Tests for Impvirities. 

Non-volatile Matter. — On evaporation, 25 c.c. of acetone should leave 
no residue. 

^ Cf. the section on " Explosives," Vol. II., Part I., pp. 492 et seq. 

'^ For identifying and colour reactions, cf. Pharvi, Ztntralh.^ 36, 616 ; 37, 439 ; Z. anal, C/icm., 
1893, 32, 347 ; 1898, 37, 47 ; Cheni. Zeit., 1909, 33, 570 ; and Merck's Reag.-Verz., 1908, p. 289. 



ACETONE 309 

Free Acid. — Blue litmus paper should not be reddened. 

Einpyreuniatic Matter. — A mixture of equal parts of acetone and 
water should be clear. 

Aldehyde} — A mixture of lo c.c. of acetone and 5 c.c. of ammoniacal 
silver solution is warmed for fifteen minutes in a water-bath at 50", the 
test being carried out in the dark. No darkening of the solution or 
separation of metallic silver should take place. (The silver solution 
for this test is prepared by mixing 10 c.c. of a 5 per cent, silver 
nitrate solution with 5 c.c. of 10 per cent, ammonia.) 

Action of Potassium Permanganate. — lo c.c. of acetone to which is 
added a drop of potassium permanganate solution (i : 1000) should 
retain the pink colour for at least fifteen minutes at a temperature not 
above 15°. By this test the presence of aldehyde is indicated.^ The 
usual requirement in this country is that a distinct colour should remain 
for thirty minutes when i c.c. of a o-i per cent, pure permanganate 
solution is added to 100 c.c. of acetone at i5°-5. Acetone containing 
0-5 per cent, by volume of aldehyde discolours the permanganate in five 
minutes, and if it contains 0-25 per cent, by volume of aldehyde, the 
discoloration is complete in ten minutes. Free mineral acids should 
not be present, since these discharge the permanganate colour in the 
case of aldehyde-free acetone. 

Water. — 30 c.c. of acetone are shaken in a closed flask with ignited 
potassium carbonate, when the latter should show no signs of becoming 
damp. On mixing 50 c.c. of acetone with 50 c.c. of petroleum spirit 
(boiling point 40°-6o°) no indication of the separation of the liquid into 
two layers should be visible. 

Quantitative Estimation. 

G. Kramer has worked out a method for determining acetone in 
methyl alcohol, which may be equally well applied to its estimation in 
commercial acetone. For this purpose acetone is diluted with 9 parts 
of water, sufficient sodium hydroxide solution and iodine solution 
added, and the mixture extracted with an accurately measured quantity 
of ether, which dissolves out the iodoform formed. An aliquot part of 
the ethereal solution is then evaporated off on a weighed clock-glass, the 
residue dried over sulphuric acid and weighed. From the weight of 
iodoform found the content of acetone is calculated ; 3-94 g. of iodo- 
form correspond to 0-58 g. of acetone.^ 

Volumetric modifications of this method are described below under 

1 <7. Vol. II., Part I., p. 493. 

"^ For the detection of aldehyde, cf. also Z. anal. C/iein., 1883, 22, 259 ; 1891, 30, 208 ; 1895, 
34. 226. 

^ Be}-., 1880, 13, 1000. On a source of error in this method of estimation, f/ Vaubel and 
Scheuer, Z. angew. Chem.^ 1905) 18, 214. 



310 ORGANIC PREPARATIONS 

the estimation of acetone in methyl alcohol (p. 364) and in the section 
on " Explosives," Vol. II., Part I., p. 493. 

H. Strache ^ has proposed a method which consists in converting 
the ketone, in sodium acetate solution, into the hydrazone by means of 
an excess of phenylhydrazine. The hydrazone is not acted upon by 
Fehling solution, but the excess of phenylhydrazine is decomposed by 
hot Fehling solution giving up its nitrogen completely, which latter 
may be determined gas-volumetrically. The nitrogen found gives the 
unused phenylhydrazine ; the used phenylh}drazinc is obtained by 
difference, from which data the acetone can be calculated. - 

Acetyl Salicylic Acid (Aspirin). 

O.COCHgCO 
CgH / . Molec. wt. i8o-o6. 

\C00H(2) 

Acetyl salicylic acid forms small white crystalline needles possessing 
a slightly acid taste, which dissolve in 300 parts of water, readil)' in 
alcohol and in sodium hydroxide and sodium carbonate solutions. 
Melting point, 175°. 

When 0-5 g. of acetyl salicylic acid is boiled for two to three 
minutes with 10 c.c. of sodium hydroxide and, after cooling, dilute 
sulphuric acid added, a transitory violet coloration is first produced, 
and then a white crystalline precipitate of salicylic acid separates out. 
If the precipitate is filtered off, the filtrate smells of acetic acid, and on 
boiling with a little alcohol and sulphuric acid gives the characteristic* 
smell of ethyl acetate. 

Tests for Impurities. 

Salicylic Acid. — A solution of o-i g. of acetyl salicylic acid in 5 c.z. 
of alcohol, prepared in the cold, to which 20 c.c. of water are added, 
should not give an immediate violet coloration on the addition of a 
drop of ferric chloride solution. 

Hydrochloric and Sulphuric Acids. — If i g. of acetyl salicylic acid is 
shaken for five minutes with 20 c.c. of water, the filtrate should remain 
clear on the addition of silver nitrate and of barium nitrate solutions. 

Organic Impurities. — i g. of acetyl salicylic acid should dissolve to a 
colourless solution in 10 c.c. of concentrated sulphuric acid. 

Inorganic Impurities. — On burning off i g. of acetyl salicylic acid, no 
appreciable residue should be left. 

' .Monatsh., 1891, 12, 524 ; Z. anal. C/iem., 1892, 31, 573. 

- For detecting and estimating wood spirit in acetone, cf. F. W. Rabington, J. Soc. Chem. 
Ind., 1907, 26, 243. 

For the quantitative estimation of acetone in crude acetone, cf. G. Heikel, Chtm, Zeil., 1908, 
32, 75 ; /• So<^- Chem. /W., 1908, 27, 114 ; and S. J. M. Auld, J. Soc. Chem. htd., 1906, 25, 100. 



AMYL ACETATE 311 



Quantitative Estimation. 



I g. of acetyl salicylic acid is boiled for three minutes with 15 c.c. of 
Ay I sodium hydroxide solution, allowed to cool, and then titrated with 
Nji hydrochloric acid, using phenolphthalein as indicator; 3-9 c.c. of 
Nji hydrochloric acid should be necessary to discharge the red colour. 
I c.c. of Nji sodium hydroxide corresponds to 0-09003 g. of acetyl 
salicylic acid. 

Amyl Acetate. 

CH3 . COOQH,^. Molec. wt. 130-1 1. 

Amyl acetate (isoamyl acetate) is a colourless, mobile, peculiar 
smelling liquid. Chemically pure amyl acetate has a sp. gr. of 0-8692, 
and boils at 138°. The commercially pure products which come on to 
the market have a sp. gr. of 0-867-0-869, and boil between 135°- 142°. 

Amyl acetate dissolves readily in alcohol, ether, benzene, chloroform, 
and glacial acetic acid, but is quite insoluble in water. 

Tests for Impurities. 

Inorganic and non-volatile Organic Compounds. — 10 c.c. of amyl 
acetate should not leave more than 0-5 mg. of residue on evaporation. 

HydrocJiloric Acid and Sulphuric Acid. — On shaking 30 c.c. of amyl 
acetate with 15 c.c. of water, the separated water should at most only 
give a slight opalescence with silver nitrate solution, and should show 
nothing with barium chloride solution, even on standing for some time. 
(The separated water always reacts acid on account of the presence of 
small quantities of free acetic acid.) 

Alcohol. — On shaking 25 c.c. of amyl acetate with 25 c.c. of a 
saturated calcium chloride solution and allowing the liquids to 
separate completely, the calcium chloride solution should, at most, show 
an increase in volume not greater than i c.c. 

Note. — Amyl acetate comes into commerce in 10 per cent, alcoholic 
solution, as pear oil. On treating such a product with calcium chloride 
solution it gives up about 90 per cent, of its volume to the latter ; for 
this reason it is better to shake up with a proportionally large volume 
of calcium chloride solution. It is generally sufficient in dealing with 
such products to only take notice of the content of amyl acetate. The 
content of alcohol cannot be judged from the specific gravity, since 
alcohol of 75-76 per cent, by volume has the same specific gravity as 
amyl acetate. 

Water. — Amyl acetate should dissolve to a clear solution when 
mixed with ten times its volume of benzene. The purest, anhydrous 
amyl acetate mixes in the same proportion (i : 10) with petroleum spirit 



312 ORGANIC PREPARATIONS 

and with official paraffin oil (liquid paraffin), producing perfectly clear 
solutions. The test with the latter is specially sensitive. 

Amyl Nitrite. 
(CH3).,CH.CH,.CHo.O.NO. Molec. wt. 117-10. 

Amyl nitrite is a clear yellow liquid with a fruity smell. It is quite 
insoluble in water, but mixes with alcohol and ether in all proportions. 
Authorities differ as to the boiling point; Hilger gives 94°-95°, 
Bernthsen 96^ Dunstan and Williams ^ 97°, Chapman- 97°-98, and 
Guthrie '"^ 99°. Dunstan and Williams give a sp. gr. of o-88o, 
Hilger of 0-902, the British Pharmacopoeia of 0-870-0-880, and the 
German Pharmacopoeia of 0-875-0-885. The commercial preparations 
generally have a lower boiling point than given above. A sample, 
however, which begins to boil at 90^ cannot be pure, even if it other- 
wise conforms to requirements, whilst a sample boiling above 99° points 
to a too high content of amyl alcohol. It is to be borne in mind that 
amyl nitrite continually undergoes slow decomposition, which may 
account for variations in the boiling point and specific gravity as well 
as in the content of acid and of amyl alcohol. 

Amyl nitrite burns with a yellow, luminous, smoky flame. On the 
addition of hydrochloric acid and a few crystals of ferrous sulphate a 
brown coloration is produced. 

Tests for Impurities. 

Free Nitrous Acid. — A mixture of i c.c. of water, o-i c.c. of ammonia 
(sp. gr. 0-96), and 2 drops of tincture of litmus shaken up with 5 c.c. 
of amyl nitrite should not be reddened ; this indicates a maximum 
content of about 0-35 per cent, of nitrous acid. 

Valeryl Aldehyde. — A mixture of i c.c. of amyl nitrite, 1-5 c.c. of 
silver nitrate solution, 1-5 c.c. of absolute alcohol, and a few drops of 
ammonia should not be turned brown or black on gently warming. 

Water. — Amyl nitrite should not become turbid when cooled down 

to o^ 

Ethyl Alcohol. — 10 c.c. of water and 10 c.c. of amyl nitrite are shaken 
up in a graduated measuring cylinder. If alcohol is present in not too 
small a quantity, the volume of water increases. The separated water 
will give the iodoform reaction. 

Quantitative Estimation. 

Amyl nitrite may be estimated volumetrically in various ways. 

1 Pharm.J., 1888, 19, 487. - Laboratory, 1867, p. 375. 

^ J. Chem. Soc, 1859, II, 245. 



AMYL NITRITE 313 

The method given for estimating ethyl nitrite, by E. Schmidt,^ may be 
applied, as also that by Curtmann.^ 

The best and simplest method is the gas-volumetric estimation, 
which is carried out as follows : — 26 g. of amyl nitrite are diluted with 
91 per cent, alcohol to 500 c.c. in a measuring flask. 5 cc. of the dilute 
alcoholic solution are introduced into a nitrometer (Vol. I., Part I., p. 
132), and 10 c.c. of potassium iodide solution (i : 5) and then 10 c.c. of 
Nji sulphuric acid added. The volume of nitric oxide evolved is 
measured and corrected for temperature and pressure. It generally 
suffices when reading off the volume at about 20" to reckon ever)- cubic 
centimetre of gas as equivalent to 2 per cent, of amyl nitrite. A good 
sample of amyl nitrite would liberate at least 40 c.c. of nitric oxide, 
equivalent to 80 per cent, of amyl nitrite, whilst a pure 100 per cent, 
sample would yield 50 c.c The reaction proceeds according to the 
following equation : — 

C5H11NO.+ KI + H.3SO, = I + KHSO^ + QHiiOH + NO. 

At normal pressure, i c.c. of nitric oxide at 0° weighs 0-0013402 g. 
If it is desired to take accurate readings, the volume found is reduced 
to 0° and 760 mm. pressure by the following formula : — 

^ _ 76o.(i+0'0366/) 

where Vq is the corrected volume at 0°, V^ is the observed volume, 
b the observed atmospheric pressure, and t the observed temperature. 

The following quite good method for the estimation of amyl nitrite 
is prescribed by the Dutch Pharmacopceia : — 0-5 g. of amyl nitrite are 
dissolved in 10 c.c. of alcohol, and 15 c.c. of an aqueous solution of 
potassium chlorate (i : 20) and 5 c.c. of nitric' acid (sp. gr. 1-316) added. 
The mixture is allowed to react for one hour, with frequent shaking. 
Then 20 c.c. of iV/io silver nitrate solution and 5 drops of an aqueous, 
saturated solution of ferric ammonium sulphate are added, and the 
excess of silver nitrate determined by titration with A710 ammonium 
thiocyanate solution. Not more than 8-6 c.c. of the thiocyanate solution 
should be required to produce a red coloration ; this condition corre- 
sponds to a minimum content of 80 per cent, of amyl nitrite, i c.c. of 
A710 silver nitrate solution = 0-0351 g. of CgH^iNO.,. 

Apomorphine Hydrochloride. 

C17H17O2N . HCl. Molec. wt. 303-61. 

Apomorphine hydrochloride crystallises in small white or grey 
crystals which are soluble in about 50 parts of water and 40 parts 

1 Pharmazeutische Chetnie., 3rd edition, vol. ii., p. 567. 

^ C/. Siidd, Apoth. Zeit., 1898, p. 716 ; also ibid., 1896, pp. 66 and 305, for a description and 
criticism of different methods of estimation. 



314 ORGANIC PREPARATIONS 

of alcohol (of about 85 per cent, by weight). It is quite insoluble 
in ether and chloroform. The solutions react neutral with littnus 
paper and gradually turn green on standing in the light and in 
air ; if some hydrochloric acid, however, is added to the solu- 
tions they remain unchanged for a longer time, but the addition 
of too much hydrochloric acid causes apomorphine hydrochloride to 
separate out. On standing over sulphuric acid, apomorphine hydro- 
chloride gradually loses in weight to the extent of about 3-6 per cent. 
The salt dried in this way regains its original weight on exposure to 
the air. 

Apomorphine hydrochloride dissolves in nitric acid, producing 
a blood-red coloration. The addition of a drop of very dilute ferric 
chloride solution to an aqueous solution of the salt (i : 10,000) turns 
the latter blue. If to 10 c.c. of an aqueous solution (i : 10,000) i c.c. of 
chloroform is added, and after the addition of sodium h)droxide solution 
the mixture is im.mediately shaken with air, the aqueous liquid assumes 
a transitory reddish-violet, and the chloroform a blue coloration. Silver 
nitrate solution produces with an aqueous solution of the salt, after the 
addition of a drop of nitric acid, a white curdy precipitate which 
is blackened immediately on the further addition of ammonia. 

Tests for Impvirities. 

Oxidation Products of Apomorphine. — A freshly prepared solution 
(i : 100 of water) should be colourless or only very faintly coloured. 
5 c.c. of ether shaken with 01 g. of dry apomorphine hydrochloride 
should remain colourless or show only a very faint pink coloration. 

Other Alkaloids. — If 01 g. of apomorphine hydrochloride be placed 
on a small, dry filter paper, and 5 c.c. of a mixture of i c.c. of hydro- 
chloric acid with 4 c.c. of water poured over it, on addition of potassium- 
mercuric iodide solution to the filtrate, at most only an opalescent 
turbidity should be produced. 

^-Cliloro-morpJiide. — 01 g. of apomorphine hydrochloride is dissolved 
in 10 c.c. of water, 20 c.c. of ether poured on, 5 c.c. of a cold, saturated 
solution of sodium carbonate added, and the mixture shaken until the 
precipitate which is first formed redissolves. The aqueous solution is 
run off, the ether well washed three times with about 20 c.c. of water, 
and then completely evaporated off in a test tube. To the cooled 
residue 5 c.c. of concentrated nitric acid containing 05 percent, of silver 
nitrate are added, and after standing for ten minutes the test tube is 
placed in a boiling water-bath for one hour. At the end of this time 
there should be no appreciable flakes of silver chloride at the bottom 
of the clear, undiluted brown liquid.^ 

1 Pharm. Zentral/i., igtl, 52, 537 ; /. Soc. Chem. hid., 1911, 30, 1278. 



ATROPINE 315 

Inorganic Ivipuritics.— On ignition, i g. of apomorphine hydro- 
chloride should not leave more than 05 mg. of residue.^ 

Atropine. 

CiyH^sOgN. Molec. wt. 289-19. 

Atropine crystallises in small, colourless needles which dissolve in 
about 300 parts of water and which are readily soluble in alcohol 
(90 per cent), ether, and chloroform. Melting point, 1 15°-5. 

Tests and Quantitative Estimation. 

Hyoscyanime. — The free base should be optically inactive. The 
more hyoscyamine it contains the more laevorotatory will it be. (The 
rotatory power of hyoscyamine is (a)n = - 20°-97.) 

The tests for inorganic and organic impurities as well as for foreign 
alkaloids are carried out as described below for atropine sulphate. 

To estimate atropine volumetrically, about 01 g. is dissolved in 
50 c.c. of absolute alcohol, some pure lackmoid ^ added, and the solution 
titrated with Njio hydrochloric acid until the blue colour changes to 
red. I c.c. of NJio hydrochloric acid corresponds to 0-02892 g. of 
atropine. 

Atropine Sulphate. 

(Ci7H.,303N),H2S04+ H2O. Molec. wt. 694-49. 

Atropine sulphate comes into commerce in white crystalline masses 
(small crystalline needles). The melting point depends on the con- 
ditions under which it is taken. If Roth's apparatus be used, and the 
temperature raised very slowly, the best commercial product dried over 
sulphuric acid gives a melting point of 185°; if heated quickly, the 
melting point is higher, and the same product may be found to give a 
melting point as high as 190°. These differences point to the melting 
point of atropine sulphate being in reality a decomposition point. The 
melting point given by the British Pharmacopoeia is 183°. In doubtful 
cases it is safest to prepare the gold chloride double salt and to take 
its melting point, which in the case of a good preparation should not be 
above 138°. According to the instructions of the German Pharmacopoeia 
the melting point of the free base is determined. For this purpose 
ammonia is added to the aqueous solution of atropine sulphate (i : 25), 
the crystals which separate on standing collected on a small filter paper, 
washed with water and dried over sulphuric acid ; they should melt at 
115°. 

' On doubtful modern commercial preparations of apomorphine, cf. Harnack and Hilde- 
brandt, Phar7n. Zeit., 1909, 54, 938 ; 1910, 55, 6 and 693. On apomorphine hydrochloride substi- 
tutes, see Frerichs, Apoth. Zeit., 1909, p. 928. 

^ Z. atigew. C/iem., 1 903, l6, 449, 468. 



316 ORGANIC PREPARATIONS 

Atropine sulphate, which dissolves readily in water and alcohol to a 
colourless neutral solution, is difficultly soluble in ether, benzene, and 
chloroform. 

If o-oi g. of atropine sulphate is evaporated to dryness on a 
water-bath with fuming nitric acid, a pale yellow residue is left, which, 
when cold, produces a violet coloration on the addition of alcoholic 
potash.^ 

Tests for Impvirities. 

Inorganic Matter. — On ignition, o-i g. of atropine sulphate should 
not leave more than 0-5 mg. of residue. 

Organic Impurities. — o-i g. of atropine sulphate should dissolve 
without coloration in 5 c.c. of sulphuric acid. 

Other Alkaloids. — The solution in sulphuric acid should remain 
colourless on the addition of nitric acid. The aqueous solution of 
atropine sulphate (o-i : 6) should not be rendered turbid by ammonia. 

Hyoscyaniine. — The free base obtained from the aqueous solution by 
the addition of alkali and extraction with ether should, after drj'ing, 
give the melting point of atropine and be inactive in alcoholic solution. 

Water. — i g. of atropine sulphate should not lose more than 0-026 g. 
in weight on drying at 100°. 

Atropine sulphate may be titrated in pure alcoholic solution with 
A710 sodium hydroxide, using Poirrier's blue as indicator, and excluding 
carbon dioxide from the air.- {Cf. Quinine hydrochloride, p. 381.) 

Benzaldehyde. 

CoH,. COH. Molec. wt. 10605. 

Benzaldehyde is a colourless, highly refractive liquid with a character- 
istic smell. It boils at 1 77°- 1 79", and has a sp. gr. of i-046-i-054. It 
dissolves readily in alcohol, ether, benzene, chloroform, and petroleum 
spirit, but only sparingly in water (about i in 300 parts). 

Tests for Impurities, 

Inorganic Matter. — On heating, benzaldehyde burns with a ver)- 
smoky flame, and leaves no residue on ignition. 

Chlorine. — 2 g. of benzaldehyde are put into a small porcelain 
crucible, which is placed on a porcelain plate of suitable size. The 
benzaldehyde is ignited with a Bunsen burner, and a 2 litre beaker, the 
inside of which is moistened with water, is placed over the burning 
benzaldehyde, and is lifted now and again from the plate so as to 
regulate the supply of air. It is well to extinguish the flame a few 

^ For other identifying reactions, cf. Merck's Reai^.-Verz,^ IQ^S, p. 290. 
" For further details, cf. Z. angetu. Chem,, 1903, 16, 470. 



BENZALDEHYDE 317 

times and re-moisten the beaker before re-lighting. When all the 
benzaldehyde is burnt in this manner, the beaker and plate are washed 
with a little water, which is then filtered through a small filter paper, 
and the filter paper washed with water until a filtrate of 20 c.c. is 
obtained. After acidifying the filtrate with a few drops of nitric acid, 
silver nitrate solution is added which should only produce a very faint 
opalescence. 

Synthetically prepared benzaldehyde is never absolutely free from 
chlorine. 

Organic Chloride {e.g. Benzyl chloride). — 10 g. of benzaldehyde are 
subjected to distillation, and the first 10-12 drops that come over are 
collected in 5 per cent, alcoholic potash. This solution is then heated 
for some time, using a reflux condenser, and the alcohol finally evaporated 
off. The residue is taken up with water, shaken with ether to remove 
oily products, nitric acid added to the aqueous solution after pouring off 
the ether, and the separated benzoic acid filtered off. The filtrate is 
tested for chlorine with silver nitrate solution as above. 

Chloro-benzaldehyde. — 2 c.c. of benzaldehyde are shaken with 40 c.c. 
of water, 6 g. of sodium carbonate (free from chlorine) added, the 
mixture gently heated, and 5 per cent, potassium permanganate solution 
(free from chloride) added gradually until the smell of oil of bitter 
almonds has completely disappeared. If the red coloration due to per- 
manganate does not also disappear, alcohol is added, drop by drop, 
until the solution is colourless. The mixture is filtered and dilute 
sulphuric acid (free from chlorine) added. When quite cold, the 
separated benzoic acid is collected on a filter paper, washed with cold 
water, dissolved in sodium carbonate solution, and after the addition of 
potassium nitrate evaporated to dryness and ignited. The ignited 
residue is dissolved in water and nitric acid, made up to 20 c.c, and 
tested for hydrochloric acid with silver nitrate as above. 

Nitrobenzene. — 2 drops of phenol, 3 drops of water, and a piece of 
potassium hydroxide the size of a pea are placed in a small porcelain 
dish. The mixture is heated carefully to boiling, and then the benzalde- 
hyde under examination, shaken up with water, added. After keeping at 
the boil for some time a carmine red ring appears at the edges of the 
liquid. On the addition of a saturated solution of calcium hypochlorite 
the colour of the ring changes to emerald green in the presence 
of nitrobenzene.^ If present in appreciable quantities, nitrobenzene 
raises the specific gravity of benzaldehyde. 5 c.c. of pure benzal- 
dehyde at 12"'^ weigh from 5-2055-5-222 g. ; if it contain 25 per cent, 
of nitrobenzene the weight of 5 c.c. becomes 5-39 g. ; and if 50 per cent, 

5-57 g- 

A further test for nitrobenzene is carried out as follows: — i g. of 

' Marpurgo, Pharm. Zeitschr. /. Russland, vol. 29, p. 205. 



318 ORGANIC PREPARATIONS 

benzaldehyde, dissolved in 20 c.c. of alcohol, is diluted with water until 
a permanent turbidity is produced. Granulated zinc and sulphuric acid 
are then added. When the evolution of hv-dro^en has ceased, the 
solution is filtered, the alcohol evaporated off, and the aniline formed 
from the nitrobenzene detected as follows: — To half the filtrate, a few 
drops of potassium bichromate solution is added and the solution 
boiled for a short time ; in the presence of aniline a pale violet colora- 
tion is produced. The other half of the filtrate is neutralised with 
potassium hydroxide, and sodium hypochlorite added ; if aniline be 
present a violet coloration is formed. 

Alcohol. — If 20 c.c. of benzaldehyde are shaken up with 20 c.c. of a 
cold, saturated solution of calcium chloride, the volume of the latter 
should not be found to have increased after completely separating the 
liquids. If 3 c.c. of benzaldehyde are mixed with 10 c.c. of nitric acid 
(sp. gr. 1-4) the presence of alcohol will cause an evolution of gas and of 
red fumes. 

Water. — Benzaldehyde should dissolve to a perfectly clear solution 
in ten times its volume of petroleum spirit (boiling point 50°-75°). 

Benzoic Acid. — Benzaldehyde always contains some benzoic acid, since 
it readily oxidises in presence of air. In the purest commercial product 
1-3 per cent, is not uncommon. Up to 14 per cent, of the acid remains 
dissolved in the benzaldehyde at 15°, but if the proportion be larger 
it crystallises out. To estimate the benzoic acid, 10 g. of benzaldehyde 
are dissolved in 50 c.c. of dilute alcohol (70 per cent, by volume), and the 
solution titrated with N\\ sodium hydroxide solution (i c.c. =0-122048 g. 
benzoic acid), using phenolphthalein as indicator. 

Hydrocyanic Acid. — 2 c.c. of benzaldehyde are shaken with 20 c.c. of 
TV/i potassium hydroxide solution, a few drops of ferrous sulphate 
solution added, and the mixture heated nearly to boiling. Hydro- 
chloric acid is then added in excess, and then a drop of ferric chloride 
solution. If hydrocyanic acid be present it will be recognised b)' the 
formation of Prussian blue. 

II)'drocyanic acid occurs in oil of bitter almonds, and can therefore 
be found in benzaldehyde prepared from this source. Oil of bitter 
almonds itself usually comes on to the market, labelled either " free 
from prussic acid" or "containing prussic acid." The oil of bitter 
almonds "free from prussic acid" is not poisonous. Natural oil of 
bitter almonds containing prussic acid can be distinguished from the 
chemically prepared benzaldehyde by a method due to A. Kremel,^ 
according to which oil of bitter almonds containing prussic acid yields 
benzoin, without the addition of potassium cyanide, whilst the chemi- 
cally prepared benzaldeh}'de docs not. 

' Pharm. Zenlralh., 30, 134. 



BENZOIC ACID 319 

Benzoic Acid. 
CgHg . COOH. Molec. wt. 12205. 

Two varieties of benzoic acid come on to tlie market, the official 
benzoic acid prepared from gum benzoin, and the chemically pure 
product prepared from either benzyl chloride, benzal chloride, benzotri- 
chloride or hippuric acid. 

(a) Official Benzoic Acid. 

This is sublimed from Siamese gum benzoin, and forms small white 
or brown leafy or needle-like crystals of a silky appearance, which 
possess a characteristic burning smell. It melts at 120°, and boils 
at 249". 

Benzoic acid dissolves in 270 parts of water at 15" and readily in 
hot water, in ether, alcohol, benzene, chloroform, petroleum spirit, and 
carbon bisulphide. 

On shaking o-2 g. of benzoic acid frequently during fifteen minutes 
with a mixture of i c.c. of iV/i potassium hydroxide solution and 
20 c.c. of water, filtering, and adding to the filtrate a drop of ferric 
chloride solution, a reddish-brown to dirty red precipitate is produced. 

Tests for Impurities. 

Official benzoic acid should melt in boiling water, when more acid 
is used than will dissolve in the quantity of water taken. Chemically 
prepared benzoic acid does not melt under these conditions. 

Inorganic and foreign Organic Matter. — On heating 0-2-0-3 g. of 
benzoic acid in a test tube, it first melts to a yellow then to a brown 
mass, and then sublimes, and should finally leave either no residue or 
only a very slight brown residue. No charring should take place ; 
should this occur it would point to the presence of sugar, hippuric, 
tartaric, or citric acids. 

Salicylic Acid. — An aqueous solution of the benzoic acid to which 
ferric chloride solution is added, and from which the precipitate pro- 
duced is filtered off should show no violet coloration. 

Suniatj-a Benzoic Acid ; Cinjiamic Acid. — i g. of benzoic acid heated 
in a closed test tube in a boiling water-bath, with i g. of potassium 
permanganate and 10 c.c. of water for from ten to fifteen minutes, should 
give no smell of oil of bitter almonds on cooling.^ 

The British Pharmacopoeia prescribes that benzoic acid should not 
develop the odour of benzaldehyde when warmed with its own weight 
of potassium permanganate, and ten times its weight of dilute sulphuric 
acid. 

^ Cf. also Schacht's reaction for Siamese benzoic acid ; Merck's Reag.-Verz,, 1008, p. 228. 



320 ORGANIC PREPARATIONS 

Chcviically prepared Acid. — I g. of benzoic acid dissolves to a yellow 
or brown solution in lo c.c. of ammonia, and the addition of excess of 
sulphuric acid causes the acid to separate out again. If to this mixture 
are added 5 c.c. of potassium permanganate solution (i : 1000), the red 
colour of the latter should completely disappear after standing for 
four hours. 

Hippuric Acid. — 0-2 g. of benzoic acid are rubbed into a paste with 
a few drops of water and 0-3 g. of pure quicklime, then dried and 
ignited. No ammonia should be liberated. 

Synthetic Benzoic Acid. — 04 g. of benzoic acid is mixed with 0-6 g. 
of calcium carbonate free from chloride, and a little water, evaporated to 
dryness on the water-bath, and then ignited. On dissolving the residue 
in nitric acid and water, and making up to 20 c.c, the addition of silver 
nitrate solution should only produce a slight opalescence. This test, 
which shows the presence of chloro-benzoic acid, and which indicates 
whether chemically prepared benzoic acid from benzalchloride, benzyl- 
chloride, benzotrichloride, etc., has been added or not, is not absolutely 
reliable. Chemically pure benzoic acid comes into commerce containing 
no more chlorine than the acid sublimed from gum benzoin, and the 
addition of such a chemically pure acid to the acid from gum benzoin 
cannot be detected b)- the above reaction for chlorine. Only gross 
adulteration by means of cheap benzoic acid containing chlorine can be 
detected in this manner. This reaction has been retained up to now, 
since for a long time it was not possible to prepare the acid chemically, 
free or approximately free from chlorine.^ H. Hagar,- in order to 
detect whether a benzoic acid is a pure product from sublimation or 
whether it has only been sublimed over gum benzoin, uses a reagent of 
doubtful value, prepared by acidifying a solution of ferric chloride and 
potassium ferricyanide with hydrochloric acid. 

(b) Chemically pure Benzoic Acid. 

This acid is distinguished from the acid obtained from gum benzoin 
by its pure white colour, its colourless solution in alcohol and ammonia, 
and its freedom from empyreumatic matter. It does not melt in 
boiling water, melts at 121-4 ^'id boils at 249". 

Tests for Impurities. 

Inorganic and foreign Organic Matter. — i g. of benzoic acid on 
heating should not leave more than 05 mg. of residue. Heated in a 
test tube it should sublime completely without charring, i g. of 
benzoic acid .should dissolve in 20 c.c. of sulphuric acid to a colourless 
or only faint yellow solution. 

' For the detection of chlorine in benzoic acid, cf. Pharm. Zeutralh., 1 899, p. 183. 
2 Pharm. Zentralh.^ 26, 392. 



BROMOFORM 321 

Chloro-benzoic Acid. — 0-4 g. of benzoic acid ignited with calcium 
carbonate and dissolved, as in the case with the official product, should 
show no immediate opalescence on the addition of silver nitrate solution, 
and on standing for five minutes only a faint turbidity.^ 

Quantitative Estimation. 

The purity of benzoic acid may be controlled by titration with 
potassium hydroxide. For this purpose i g. of benzoic acid is dissolved 
in 10 c.c. of N\\ potassium hydroxide solution, diluted with 40 c.c. of 
water, and titrated with A^i hydrochloric acid, using phenolphthalein 
as indicator, i c.c. of Nji potassium hydroxide corresponds to 0-122048 
g. of benzoic acid. 

Bromoform. 

CHBrg. Molec. wt. 25277. 

Bromoform is a colourless liquid with a smell somewhat similar to 
that of chloroform. It is very sparingly soluble in water, but is 
miscible in all proportions with alcohol, ether, benzene, and petroleum 
spirit. The purest bromoform has a sp. gr. of 2-904, melts at 9°, and 
boils at I49°-I50°. 

Tests for Impurities. 

Non-volatile Matter. — 20 c.c. of bromoform should leave no residue 
on volatilisation. 

Bromine. — Bromoform should be quite colourless. On shaking 5 
c.c. of bromoform with 5 c.c. of water, and i c.c. of zinc iodide-starch 
solution, the bromoform should remain colourless and the starch 
solution should not be immediately turned blue. 

Hydrobromic Acid. — On shaking 10 c.c. of bromoform with 10 c.c. of 
water, the separated water should not immediately redden blue litmus 
paper. On carefully pouring the separated water on to silver nitrate 
solution, no opalescent ring should be visible at the point of contact of 
the two layers of liquid. 

Foreign Orgastic Matter. — On shaking 10 c.c. of bromoform with 
10 c.c. of sulphuric acid in a glass cylinder, previously washed out with 
sulphuric acid, the sulphuric acid should remain colourless for ten 
minutes. 

Aldehyde. — On shaking 20 c.c. of bromoform with 10 c.c. of water, 
the separated water, on the addition of ammonia and silver nitrate 
solution, should show no reducing action on the silver nitrate for at 
least half an hour.^ 

1 Pharm. Zentral/i., 1900, pp. 449, 529. 

2 On the decomposition of bromoform by light and air, cf. Berichte der deutschen Pharm. Ges. 
Berlin, 1905, p. 387 ; y. Soc. Cliem. Ind,, 1906, 25, 232. 

Ill X 



322 ORGANIC PREPARATIONS 

Caffeine. 
C,HO,N,(CH3)3+H,0. Molec. wt. 212-14. 

Caffeine crystallises in white, glistening, flexible needles which are 
soluble in So parts of water, 50 parts of alcohol (of about 85 per cent, 
by weight), and in 9 parts of chloroform ; it is but spariiigl}' soluble in 
ether. It effloresces in the air and loses its water of crystallisation 
completely at 100°. Melting point 235°. 

An aqueous solution of caffeine is precipitated by tannic acid 
solution ; the precipitate is soluble in an excess of the precipitating 
reagent. On evaporating a solution of i part of caffeine in 10 parts 
of chlorine water on the water-bath a yellowish-red residue remains, 
which changes to a beautiful purple-red colour on immediately treating 
with a little ammonia.^ 

Tests for Impurities, 

Alkaloids. — Caffeine should dissolve to a colourless solution in 
concentrated sulphuric acid and in nitric acid. A cold, saturated 
solution of caffeine in water should not be rendered turbid by chlorine 
water or by iodine solution, and should remain colourless on the 
addition of ammonia. 

Inorganic Impurities. — i g. of caffeine should volatilise on heating 
without charring, and should not leave more than 0-5 g. of residue. 

Caffeine is considerably more soluble in water in the presence of 
various salts such as sodium benzoate, sodium salicylate, and sodium 
cinnamate, than in water alone. This increased solubility is due to the 
formation of double salts ; of these double salts caffeine-sodium salicylate 
and caffeine-sodium benzoate are the most important, and find applica- 
tion in pharmacy. 

Caffeine-sodium Salicylate. 

This double salt is prepared by evaporating a solution of 5 parts of 
caffeine and 6 parts of sodium salicylate in 20 parts of water. It is 
a white, amorphous powder or a white, granular mass containing 43-8 
per cent, of caffeine, and is soluble in 2 parts of water and in 50 parts of 
alcohol (of about 85 per cent, by weight). On heating in a narrow test 
tube white vapours smelling of phenol are evolved, and the residue 
effervesces on treatment with acids. The aqueous solution even 
when very dilute (i : looo) gives a blue-violet coloration with ferric 
chloride. On warming the double salt with chloroform, the filtered 
liquid yields a crystalline residue on evaporation, which may be identified 
as caffeine. 

^ For identifying reactions, cf. Merck's Reag.-Verz., 1908, p. 292. 



CAFFEINE. CAMPHOR 323 

Tests for Impurities. 

An aqueous solution of caffeine-sodium salicylate (1:5) should be 
colourless. The double salt should dissolve in concentrated sulphuric 
acid without effervescence and to a colourless solution (sodium carbonate, 
sugar). 

Heavy Metals and SnlpJinric Acid. — The aqueous solution (i : 20) 
should remain unchanged by sulphuretted hydrogen water and by 
barium nitrate solution. 

Hydrochlo7-ic Acid. — 2 c.c. of the solution (i : 20), to which 3 c.c. of 
alcohol are added and then acidified with nitric acid, should not be 
affected by the addition of silver nitrate solution. 

Water. — Caffeine-sodium salicylate should not lose more than 5 
per cent, in weight on drying at 100". 

Quantitative Estimation of Caffeine. 

A simple method of estimation consists in shaking up a solution of 
I g. of caffeine-sodium salicylate in 5 c.c. of water, four times succes- 
sively, with about 5 c.c. of chloroform, evaporating off the chloroform, 
and weighing the residue after drying at 100". At least 0-4 g. of 
caffeine should be found in the residue. By this method, the whole of 
the content of caffeine is not found, since a portion is retained in the 
aqueous solution. 

Caffeine-sodium Benzoate. 

Externally, this preparation does not differ from the preceding 
double salt. The caffeine can be extracted with chloroform, and gives, 
after evaporating off the solvent, the reactions given above. The 
aqueous solution gives a flesh-coloured precipitate with ferric chloride. 
Caffeine-sodium benzoate is prepared by evaporating down a solution 
of 5 parts of caffeine and 5 parts of sodium benzoate in 10 parts of 
water. The testing and quantitative estimation are carried out in 
exactly the same manner as given above for caffeine-sodium salicylate. 

Camphor (Japan Camphor). 

CioHioO. Molec. wt. 152-13. 

Camphor comes into commerce in white, transparent, tough, crystal- 
line masses. For pharmaceutical purposes it is sold in the form of 
balls, cubes, and also as " Flowers of Camphor." Crystallised from 
alcohol it forms hard hexagonal crystals. It has a peculiar smell 
and taste, and is difficultly soluble in water. According to the British 
Pharmacopoeia the solubility is i : 700, according to Schmidt, i : 1200; 
it dissolves readily in alcohol, ether, chloroform, acetone, benzene, acetic 
acid, and carbon bisulphide, as well as in fatty and essential oils. Its 



324 ORGANIC PREPARATIONS 

sp. gr. is 0-985-0-996, the melting point 175° (according to J. E. Crane 
and C. M. Joyce ^ iyg°'^), and the boiling point 204^ It burns 
with a luminous, smoky flame. It is dextrorotatory in concentrated 
alcoholic solution, and its specific rotatory power according to Landolt 
is (0)0 = +55-4' 

Tests for Impurities. 

Non-volatile Matter. — On heating i g. of camphor, not more than 
0-5 mg. of residue should remain. 

"Artificial" Cavtphor {Terpene hydrochloride). — Japan camphor, 
when rubbed with an equal quantity of chloral hydrate, should 
give a syrupy liquid, whilst, according to Hirschsohn,^ " artificial " 
camphor does not become liquid when treated in this manner.^ Since 
" artificial " camphor contains chlorine it is readily identified. To test 
for its presence 0-5 g. of the sample is stirred into a molten mixture of 
potassium hydroxide and potassium nitrate, gently ignited, the cold melt 
dissolved in nitric acid and water, and the solution made up to 50 c.c. ; 
on the addition of silver nitrate solution no turbidity should be 
produced. 

Synthetic CampJior. — The synthetical preparation of camphor has 
made such advances in recent }-ears that synthetic camphor has now 
become a commercial product. It has the same chemical composition 
as the natural product, but possesses different phj'sical constants which 
serve for its identification. Natural camphor is dextrorotatory, gives 
on oxidation with nitric acid an optically active camphoric acid melting 
at 187", and gives the Borisch reaction (see below). Synthetic camphor 
is optically inactive ; on oxidation it yields an optically inactive acid 
melting at 202°-203°, and does not give the Borisch reaction. In 
dealing with a mixture of natural and synthetic camphor, the optical 
method is the only means of examination, the product to be examined 
being compared optically with a genuine sample of Japan camphor, both 
in solutions of equal concentration. 

The alcoholic solution is most suitable for determining the specific 
rotatory power. For a solution in benzene Landolt and Forster give 
the following formula when using Laurent's apparatus at 20°: — 



C=,.5-205[-.+7.+ ^54367-J, 

in which C = the weight of camphor in grams per 100 c.c. of solution, 
a — angle of rotation, and / = length of tube in decimetres.* 

^ /. Soc. Chem. hid., 1907, 26, 386. 
2 Pharm. Zeit.f. Russland, 1897, p. 161. 

^ Cf. also B liley's and Dumont's reactions for ariificial camphor. Merck's Keag.-]'ers., 1908, 
pp. 12 and 65. 

* Cf. J. E. Crane and C. M. Joyce,/. Soc. Chem. Ind., 1907, 26, 386. 



CAMPHOR 325 

TJie Bon'sch Reaction. — On warming carefully 0-05 g. of camphor in a 
test tube with i c.c. of vanillin-hydrochloric acid, as the temperature 
gradually rises a rose-red coloration is first produced, which between 
75°-ioo° changes to a greenish - blue. This reaction only takes place 
with natural camphor ; synthetic camphor gives no coloration. The 
test may be carried out in the cold as follows: — About o-i g. of 
camphor is treated on 2 watch-glass with 10 drops of a cold 
mixture of equal volumes of vanillin -hydrochloric acid (i g. of 
vanillin in 100 g. of 25 per cent, hydrochloric acid), and concen- 
trated sulphuric acid added. A yellow coloration is at first pro- 
duced, and in the course of half an hour to one hour in the case 
of natural camphor this changes to a dirty green coloration, and 
in the course of another hour to a pure dark green, and after seven 
to eight hours to an indigo -blue colour. (Impurities in natural 
camphor mask the reaction.) Synthetic camphor treated in a similar 
manner only shows the initial yellow coloration, which disappears at 
the end of an hour.^ 

The oxidation of camphor is carried out as follows: — 5 g. of camphor 
are placed in a small^ flask fitted with a long vertical glass tube 
or upright Liebig's condenser, and heated on the boiling water-bath for 
about fifty hours with a mixture consisting of 24 c.c. of nitric acid 
(sp, gr. I 42) and 16 c.c. of water. The camphoric acid which has 
separated is then collected, washed with cold water, recrystallised from 
hot water, converted into the sodium salt, again separated by the 
addition of hydrochloric acid and recrystallised several times from hot 
water. As stated above, natural camphor yields by this treatment an 
acid melting at 187°, whilst synthetic camphor yields an acid melting at 
2O2°-203°, or, as is frequently the case, no acid at all, owing to the 
oxidation having proceeded too rapidly.^ 

Carbon Bisulphide. 

CSg. Molec. wt 76-14. 

Carbon bisulphide is a colourless, bright, neutral, highly refractive, 
easily inflammable liquid, having a sp. gr. of i-270-i-272, and a boiling 
point of 46°-47°. 

Tests for Impurities. 

Pure carbon bisulphide contains generally only sulphur as an 
impurity, which is found in traces in practically all of the purest 
commercial brands. On evaporating 50 c.c. of carbon bisulphide on 

^ Pharm. Zentralh.y 1907, 48, 527 and 777 ; J. Soc. Chem. Ind.^ 1907, 26, 1065. 
"^ Cf. Deussen, Arch. Pharm., 1909, 247, 3 1 1. On testing synthetic camphor, cf. A. Baselli, 
J. Soc. Chem. Ind.y 1907, 26, 431. 



326 ORGANIC PREPARATIONS 

the water-bath, only a trace of sulphur should remain. On shaking 
carbon bisulphide with lead carbonate, the latter should not be turned 
brown (absence of sulphuretted hydrogen). 

Sulpliuric and Sulphurous Acids. — On shaking lo c.c. of carbon 
bisulphide with 5 c.c. of water, the latter should neither redden nor 
bleach blue litmus paper. 

Quantitative Estimation. 

A quantitative estimation of carbon bisulphide is usually not 
necessary if the sample conforms to the tests given above. If, however, 
a quantitative valuation be required, the method based on A. \V. 
Hofmann's xanthate reaction may be used.^ A weighed quantity 
of carbon bisulphide is added to alcoholic potassium hydroxide, and 
after allowing to react for a short time the mixture is acidified with 
acetic acid and insoluble cuprous xanthate (a yellow crystalline pre- 
cipitate) precipitated by the addition of copper sulphate. The con- 
tained copper may be estimated either volumetrically according to 
Grete- and Macagno,^ or weighed as cupric oxide. From the weight 
of copper found the value of the carbon bisulphide may be calculated, 
since one equivalent of copper corresponds to two equivalents of carbon 
bisulphide.* 

Carbon Tetrachloride. 

CCI4. Molec. wt. 153-84. 

Carbon tetrachloride is a colourless liquid, sparingly soluble in water 
(about o-o8 to 100), miscible in all proportions with absolute alcohol, 
ether, fatty and essential oils. Its sp. gr. is 1-604, ^^^^ its boiling point 
76°-77°. 

Tests for Impurities. 

Non-volatile Matter. — On evaporating 25 c.c. of carbon tetrachloride 
on the water-bath, no appreciable residue should be left. 

Chlorine. — No blue coloration should be produced on shaking 20 c.c. 
of carbon tetrachloride with 5 c.c. of zinc iodide-starch solution. 

Hydrocliloric Acid. — 20 c.c. of carbon tetrachloride are shaken with 
10 c.c. of water for about one minute. The separated water should not 
react acid and should show no reaction with silver nitrate solution. 

Organic Impurities. — On shaking 20 c.c. of carbon tetrachloride 
frequently during one hour with 15 c.c. of concentrated sulphuric acid in 

» Cf. section on "Coal Tar," Vol. II., Part II., p. 796. 

2 Z. anal. Chem., 1882, 21, 133. ' Ibid. 

* Cf. A. Goldberg, Z. angrw. Chem., 1899, 12, 75 ; /. Soc. Ch<m, Ittd., 1889, 18, 304. 



CARBON TETRACHLORIDE 327 

a stoppered glass vessel, previously rinsed out with sulphuric acid, the 
sulphuric acid should not become coloured. 

Aldehyde. — If a mixture of lo c.c. of carbon tetrachloride and lo c.c. 
of potassium hydroxide solution (1-3) be warmed for about one minute 
and frequently shaken during the warming, the potassium hydroxide 
should not become either yellow or brown in colour. 

Carbon Bisulphide. — 10 c.c. of carbon tetrachloride are mixed with 10 
c.c. of a solution of 10 g. of potassium hydroxide in 100 c.c. of absolute 
alcohol. After standing for one hour, 5 c.c. of dilute acetic acid (sp. gr. 
I-04-I-042) and copper sulphate solution are added. No yellow 
precipitate should separate within two hours. 

Any carbon bisulphide present may be quantitatively determined by 
the iodometric method worked out by L. G. Radcliffe,^ as an applicable 
modification of Gastine's form, of the xanthate reaction. The method is 
based on the conversion of the carbon bisulphide into xanthic acid by 
means of alcoholic potash, separating it by the addition of acetic acid, 
and titrating with iodine solution, whereby it is oxidised to ethyl dithio- 
dicarbonate. To carry out the determination, 25 c.c. of alcoholic potash 
are run into a flask of suitable size, and the flask loosely closed with a 
cork and tared ; i c.c. of the carbon tetrachloride under examination is 
then run in from a pipette and the total weight accurately determined. 
After five minutes, dilute acetic acid is added until the mixture reacts 
faintly acid (discoloration of phenolphthalein), the contents of the flask 
cooled, and solid sodium bicarbonate added in excess. The milky, 
turbid mixture is titrated with Njio iodine solution after the addition 
of starch solution. One molecule of xanthic acid corresponds to one 
atom of iodine, as shown in the following equation : — 

/OC2H5 
2CS<( +I2 = S,(CS.OC2H5)2+2HI. 

\5J^ Ethyl dithio-dicarbonate 

Xanthic acid 

Casein. 

Casein, an albuminoid constituent of milk, is a fine, white or 
yellowish-white powder, insoluble in water and in alcohol. Sprinkled 
on moist blue litmus paper, the latter is turned red. It is soluble in 
aqueous solutions of the alkali hydroxides and alkaline earths, as well as 
in alkaline carbonates, and is precipitated out from these solutions by 
acids. Excess of alkali converts it into albuminate. On artificial 
digestion in 02 per cent, hydrochloric acid with pepsin at about 40°, 
the clear solution of casein gradually becomes turbid owing to the 
separation of nuclein. 

^ /. Soc. Chem. I>id., 1 909, 28, 229. 



328 



ORGANIC PREPAKATIONS 



According to Scherer ^ and O. Hammarsten - the elementary com- 
position of casein is as follows : — 





Scherer. 


Hammarsten 




Per cent. 


Per cent. 


Carbon . . . . 


54-02 


52-96 


Hydrogen 


7-33 


7-05 


Nitrogen 


15-52 


15-65 


Sulphur . 


075 


0-71 


Phosphorus 


• • • 


0-85 


Oxygen . 


22-38 


22-78 



Phosphorus is a constituent of casein itself, though it was formerly 
assumed to be only a constituent of the contained mineral matter left 
on ignition. 

Tests for Impurities. 

Inorganic Matter. — On burning i g. of casein in free access of air, 
only a trace of ash should remain behind. The purest casein yields 
up to 0-5 per cent, of ash (according to Hammarsten up to 1-2 per 
cent), commercial casein as much as 6 per cent, and the purest casein 
from plants up to i per cent In judging casein, these figures for 
the percentage of ash may generally be considered as the maxima. 
Sodium casein sometimes comes on to the market under the designa- 
tion of casein. The salt is readily recognised by its solubility in water 
and high percentage of ash (sodium carbonate). 

Fat. — 10 g. of casein are well shaken frequently for one hour with 
100 c.c. of ether, 50 c.c. of the ethereal extract filtered through a dry 
filter paper into a small weighed flask, well covering the funnel to avoid 
loss of ether by evaporation, and the ether evaporated off on the water- 
bath. The residue is then dried for two hours at 90"- 100'' and weighed. 
Good casein should not contain more than o-i per cent of fat In the 
purest casein up to 0-07 per cent., in commercial casein up to 0-09 per 
cent, and in casein from plants up to o-oi per cent, of fat will be found. 

Free Acid {^Acetic Ada). — The purest casein should contain no free 
acid, which, however, is frequently not the case with commercial 
products. On shaking 10 g. of casein with 100 c.c. of water, the filtrate 
should react only slightly acid ; 50 c.c. of the filtrate may be titrated 
with TV/ 10 potassium hydroxide, using phenolphthalein as indicator. A 
good sample should not require more than 05 c.c. of the iV/io 
potassium hydroxide to produce a red coloration. 

Quantitative Estimation. 

This may be carried out by determining the content of nitrogen 
either by Dumas' or Kjeldahl's method. Taking the nitrogen con- 

1 Annalen^ 1841, 40, 41. 

2 Z. physiot. Chem., 1882-3, 7, 269; c/. also Tangl, PJliiger's Arckiv der Physiol., 1908, 

121, S34- 



CATECHOL 329 

tent of milk albumin as 14-3 per cent, the calculation used in the 
analysis of casein is to multiply the percentage of nitrogen found in 
the sample under examination by 6-99. A good sample of casein is 
expected to give a value of 100 when multiplied by this factor. 

According to H. D. Richmond^ the Kjeldahl method is better and 
more reliable than the Dumas method for the estimation of nitrogen in 
casein. Experimental results gave a mean value of 15-65 per cent, of 
nitrogen in casein, corresponding to the factor 6-39. 

Catechol (Pyrocatechin). 

OH(i) 
CgHZ . Molec. wt. 110-05. 

^OH(2) 

Catechol forms colourless, glistening, slightly odourous, rhombic 
scales or columnar crystals, readily soluble in ether, alcohol, benzene, 
chloroform, and water. The aqueous solution reacts acid. It melts at 
104°, and boils at 240°-245°. 

An aqueous solution of catechol gives a green coloration with ferric 
chloride ; on the addition of a little sodium hydroxide the colour 
changes to violet, and with excess to deep red. Silver nitrate is 
reduced by catechol in the cold, but Fehling solution is only reduced 
on heating. The aqueous solution is precipitated by lead acetate as 
well as by the basic acetate. This differentiates catechol from resor- 
cinol and quinol ; resorcinol in aqueous solution is precipitated by basic 
lead acetate, but not by the normal acetate, whilst quinol is precipitated 
by neither of these reagents.- 

Tests for Impurities. 

Inorganic Matter. — i g. of catechol should not leave more than 0-5 
mg. of residue on ignition. 

Phenol. — On boiling an aqueous solution (i:io) it should not be 
possible to recognise the smell of phenol. 

Foreign Organic Matter. — Catechol dissolves in sulphuric acid 
producing a faint rose coloration ; no darkening of the sulphuric acid 
should take place. 

Quantitative Estimation. 

0-5 g. of catechol is dissolved in 50 c.c. of water and a concentrated 
aqueous solution of lead acetate gradually run in, the contents of the 
beaker being kept agitated during the addition. After allowing the 
white precipitate (CgH^OgPb) to settle, a few more drops of lead acetate 

1 Analyst, 1908, 33, 1 79. 

2 For colour reactions, cf. Chem. Zentr., 1898, II., 1282 ; Z. anal. Chem., 1889, 28, 252, and 

1895, 34. 235- 



330 ORGANIC PREPARATIONS 

solution are added in order to see if the precipitation is complete, and 
the precipitate is then collected on a weighed filter paper. After 
washing several times with water, the precipitate is dried at lOO and 
weighed. The result obtained may be checked by igniting the 
precipitate, dissolving in nitric acid, diluting the solution with water, 
precipitating the lead as sulphate and weighing it as such. 

I g. PbC^H^Oo corresponds to 03494 g. of catechol; i g. of lead 
sulphate corresponds to 0-3632 g. of catechol. 

Chloral Hydrate. 
CCI3COH . H,0. Molec. wt. 165-40. 

Chloral hydrate forms colourless, transparent, monoclinic cr}'stals, 
which soften at 49" and melt at 53". It dissolves readily in water, 
alcohol, and in ether, but only sparingly and slowly in benzene, chloro- 
form, petroleum spirit, and carbon bisulphide. In aqueous solution it 
reacts slightl}- acid, whilst in other solvents it has a neutral reaction. 

On treating chloral hydrate with potassium hydroxide solution, 
chloroform is produced.^ The following test serves to differentiate 
between chloral hydrate and but\l-chloral hydrate : — On treating chloral 
hydrate with a solution of pyrogallol in concentrated sulphuric acid, the 
mixture remains colourless in the cold, but on warming carefully and 
gently a fine blue coloration is produced ; butyl-chloral hydrate treated 
in a similar manner yields a wine-red coloration.^ 

Tests for Impiirities. 

Inorganic Matter. — i g. of chloral h)-drate should leave no appreci- 
able residue on ignition. 

Hydrochloric Acid. — An alcoholic solution of chloral hydrate (i : 10) 
should not show any immediate turbidity with silver nitrate solution, 
and should not redden blue litmus paper. 

Chloral Alcoholate. — On pouring i c.c. of commercial nitric acid over 
I g. of chloral hydrate in a porcelain dish, no yellow coloration should 
be produced at the ordinary temperature, or on warming for from three 
to four minutes on the water-bath, and also no yellow vapours should 
be evolved even on warming for ten minutes. The British Pharma- 
copceia gives the following test : — When r g. of chloral hydrate is 
warmed with 6 c.c. of water and 0-5 c.c. of potassium hydroxide solution, 
the mixture filtered, sufficient iodine solution added to impart a deep 
brown colour, and the whole set aside for an hour, no precipitate of 
iodoform should result. 

* For identifying and colour reactions of chloral hydrate, cf. Merck's Reag.-Verz,, 1908, p. 
292. 

- Pharm. Zeit., 1 904, p. 91. 



CHLORAL HYDRATE 331 

Foreign Organic Matter. — i g. of chloral hydrate when shaken up 
with 10 c.c. of sulphuric acid in a glass vessel previously rinsed out with 
sulphuric acid should not discolour the acid within one hour. Chloral 
hydrate required for medicinal purposes should conform to the following 
more exacting test: — If 2 g. of chloral hydrate are dissolved in 10 c.c. 
of sulphuric acid (sp. gr. 1-84) in a glass-stoppered flask previously 
rinsed out with sulphuric acid, and 4 drops of formaldehyde (40 per 
cent.) added, the mixture should not become discoloured within half 
an hour.^ 

Quantitative Estimation. 

Potassium hydroxide, even in the cold, decomposes chloral hydrate 
quantitatively into chloroform and potassium formate : — 

CCI3COH.H2O + KOH = CHCI3+H.COOK + H2O. 

To carry out the estimation based on this decomposition 5 g. of chloral 
hydrate are dissolved in 50 c.c. of N\i potassium hydroxide, phenol- 
phthalein added, and the excess of alkali immediately titrated with N\\ 
hydrochloric acid. In order to arrive at the content of chloral hydrate 
in the 5 g. of the sample taken, the number of cubic centimetres of 
Nil potassium hydroxide used for the reaction is multiplied by 0-1654. 
Should the chloral hydrate contain free hydrochloric acid, 10 g. of the 
sample are treated in a 100 c.c. measuring flask with 0-5 g. of calcium 
carbonate and 50 c.c. of water, and the mixture well shaken for some 
minutes. The flask is then filled up to the mark with water, the con- 
tents well mixed and filtered, and 50 c.c. of the filtrate are then treated 
with 50 c.c. oi Nji potassium hydroxide, as given above. 

T. E. Wallis^ gives the following method :— o-i g. of chloral hydrate 
is dissolved in 10 c.c. of alcohol, 10 c,c. of NJi sodium hydroxide added, 
and the mixture heated in a suitable bottle, closed with a rubber cork 
which is securely tied down, for three hours in the water-bath. The 
resulting mixture is neutralised with vV/i sulphuric acid, using phenol- 
phthalein as indicator, and the sodium chloride formed in the reaction 
titrated with Njio silver nitrate solution. The calculation is made 
according to the following equation : — 

CCl3CH(OH)2-f5NaOH = 3NaCl + 2H . COONa + sHp. 

Not less than i8-i and not more than 18-3 c.c. of Njio silver nitrate 
solution should be required. 

The estimation of the contained chlorine is also made use of in the 
method of valuation devised by P. A. W. Self'' This consists in heat- 
ing 0-3 g. of chloral hydrate with i-o g. of aluminium powder (or 2-5 g. 

1 Merck's Ja/iresber., 1910, p. 150. ^ P/mrm.J., 1906, 76, 162. 

3 Ibid., 1907, 79,4. 



332 ORGANIC PREPARATIONS 

of zinc filings), 15 c.c. of glacial acetic acid, and 40 c.c. of water for half 
an hour under a reflux condenser. The mixture is then filtered, and, 
after washing, the chlorine in the solution is determined either gravi- 
metrically as silver chloride, or volumetrically by adding excess of ^V/io 
silver nitrate solution, filtering, and titrating the excess of silver with 
ammonium thiocyanate. 

E. Rupp^ gives the following iodometric method of estimation : — 25 
c.c. of A^jio iodine solution and 2-5 c.c. of N/i potassium hydroxide 
solution are run into a glass-stoppered flask. 10 c.c. of a i per cent, 
chloral hydrate solution are added to the above mixture, and the 
contents of the flask allowed to stand for from five to ten minutes. 
After diluting with about 50 c.c. of water and adding 5 c.c. of hydro- 
chloric acid (25 per cent.), the solution is titrated with N/io sodium 
thiosulphate solution. From 12-9- 13- 5 c.c. should be required, which 
correspond to 100-95 per cent, of chloral hydrate. The decomposition 
takes place according to the following equation : — 

CCl3CH(OH),-f U = 2HI-fC0.3 + CHCl3. 

I c.c. of the iodine solution is therefore equal to 000827 g. of chloral 
hydrate. 

Chloroform. 

CHCI3. Molec. wt. 119-39. 

Chloroform is a clear, colourless liquid, possessing a characteristic 
smell. The purest chloroform has a sp. gr. of 1-502, and boils at 62°; 
C. Baskerville and W. Hamor give the boiling point of specially purified 
chloroform as 6i°-2, and the sp. gr. at I574° as 1-49887.- The chloroform 
of the British Pharmacopoeia is prepared by the addition of sufficient 
absolute alcohol to produce a liquid having a sp. gr. of not less than 
1-490 and not more than 1-495. That of the German Pharmacopceia 
contains an addition of i per cent, of alcohol and has a sp. gr. of from 
I-485-I-489, and boils between 6o°-62°. The addition of alcohol makes 
the preparation more stable.^ 

Chloroform is only slightly soluble in water (i : 200) ; it is miscible 
in all proportions with alcohol, ether, carbon bisulphide, fatty and 
essential oils. On warming chloroform with potassium hydroxide and 
acetanilide, the disagreeable odour of isonitrile is produced. 

Tests for Impurities. 

Inorganic and noti-volatile Orgafiic ]\ fatter. — On evaporating 25 c.c. 
of chloroform, no appreciable residue should be left. 

1 Arch. P/iarm., 1903, 241, 326 ; /. Soc. Chem. Ind., 1903, 22, 1019. 

2 /. Ind. Eng. Chem., 1912, 4, 212 ; /. Soc. Chem. Ind., 1912, 31, 840. 

^ On the value of alcohol for increasing the stability of chloroform, cf. Adrian, J. Pharm, 
Chim., 1903, 18, 5 ; /. Soc. Chem. Ind., 1903, 22, 879. 



CHLOROFORM 333 

Hyd7-ocJiloric Acid. — On shaking 20 c.c. of chloroform with 10 c.c. of 
water for about a minute, the separated water should not redden blue 
litmus paper, and when poured on to silver nitrate solution the line of 
separation of the two layers of liquid should show no turbidity.^ 

Chlorine. — On shaking 20 c.c. of chloroform with 5 c.c. of zinc iodide- 
starch solution, the chloroform should not become coloured nor the 
starch solution turned blue. 

Foreign Orgattic Matter. — 20 c.c. of chloroform, 1 5 c.c. of concentrated 
sulphuric acid, and 4 drops of formaldehyde solution (40 per cent.) are 
shaken together in a glass-stoppered flask previously rinsed out with 
sulphuric acid ; the sulphuric acid should not become discoloured 
within half an hour.^ 

Carbonyl Chloride. — The smell of chloroform should not be irritating. 
20 c.c. of chloroform are treated with a solution of 3 drops of aniline in 
5 c.c. of benzene. In the presence of carbonyl chloride either a tur- 
bidity or a crystalline precipitate of phenyl urea is produced.^ On 
adding clear baryta water to 10 c.c. of chloroform, no white film should 
be produced at the junction of the two layers of liquid. 

Alcohol — Chlorofornj free from alcohol should not discolour 
potassium permanganate solution. According to H. Hager, a some- 
what high content of alcohol may be detected by shaking up chloroform 
with a mixture of 4 vols, of glycerol and i vol. of water in a graduated 
cylinder. The content of alcohol can be gravimetrically estimated by a 
method given by M. Nicloux.* 

Aldehyde. — If 10 c.c. of chloroform and 10 c.c, of potassium hydroxide 
solution are warmed together for about a minute, no yellow or brown 
coloration should result. 

The following scheme for the examination of chloroform for 
anaesthetic and analytical purposes, with particular reference to the 
detection of avoidable impurities, has been worked out by C. Baskerville 
and W. Hamor, as the result of an extended investigation of the subject.^ 
" Anaesthetic chloroform " is the term given to chloroform complying 
with pharmacopoeial requirements ; it contains ethyl alcohol (up to i 
per cent.) and small quantities of water, " Commercial chloroform " 
contains at least 99 per cent., by weight, of chloroform, but may contain 
small amounts of " organic impurities." 

I. Specific gravity is determined by means of a pyknometer at 15°. 

' On the decomposition of chloroform by air and light, cf. W, Ramsay, y. Soc. Chem. Ind., 
1892, II, 772 ; also, Ber. der deutsch. pharm. Ges. Berlin, ISOS, p, 387, and C, Baskerville and 
W, Hamor,/. Soc. Chem. /nd., 1912, 31, 840. 

2 On the preservation of chloroform for anaesthetic purposes, cf. Merck's Jahresher,, 1902, p. 
43 ; also, Z. angezv. Chem., 1910, 23, 1546, 

^ Scholvien, Pharm. Zetitralh., 34, 611, 

* Bull. Soc, Chim., 1906, 35 330 ; J. Soc. Chem. hid., 1906, 25, 611. 

5 /. Ind. Eng. Chem., 1912, 4, 212, 278, 362, 422, 499, 571 ; /. Soc. Chem. Ind., 1912, 31, 839, 



334 ORGANIC PREPARATIONS 

2. Odour. — lOO c.c. are slowly evaporated to about lo c.c. on the 
water-bath. The residue from anctsthetic chloroform should be colour- 
less and possess no foreign odour, and when allowed to evaporate on 
filter paper, no odour of other substances than alcohol and chloroform 
should be perceptible as the last portions disappear. (In the case of 
pure chloroform, no odour except that of chloroform should be 
observed.) 

3. Residue. — No appreciable residue should be left when 100 c.c. 
of pure or anaesthetic chloroform are evaporated in a platinum dish 
at 100°. 

4. Organie Impurities. — 20 c.c. of the sample are mixed with 15 c.c. 
of concentrated sulphuric acid in a glass-stoppered tube of 50 c.c. 
capacity, and after the addition of 0-4 c.c. of pure 40 per cent, form.al- 
dehyde solution, the whole is shaken for five minutes. No coloration 
should be produced with anaesthetic chloroform, and with pure chloro- 
form no coloration should be produced even on allowing to stand for 
one hour in the dark. 

5. Water. — When 20 c.c. of the sample are boiled with i g. of clean 
crystals of calcium carbide, and the vapours evolved passed into 
ammoniacal silver nitrate solution, no acetylene reaction should result 
in the case of pure chloroform or anhydrous anaesthetic chloroform.^ In 
the case of anaesthetic chloroform, 10 c.c. should dissolve to a clear 
solution when shaken with an equal volume of paraffin oil of sp. 
gr. o-88o. 

6. Alcohul. — For pure chloroform, 10 c.c. arc extracted with succes- 
sive portions of 4 c.c, 4 c.c, and 2 c.c. of concentrated sulphuric acid, 
the acid solution is diluted with 40 c.c. of water, and gently distilled 
until 20 c.c. have passed over. 10 c.c. of the distillate are treated with 
6 drops of a 10 per cent, solution of potassium hxdroxide, warmed to 
50", and treated with a saturated solution of iodine in potassium iodide 
until it becomes permanently brown, when it is carefully decolorised 
with potassium hydroxide; no iodoform should be deposited. A 
negative result with this test indicates the absence of alcohol, acetalde- 
hyde, propyl alcohol, acetone, etc. Tests with chromic acid,'- alkaline 
permanganate,^ and potassium hydroxide (agitation of the sample first 
with ignited potassium carbonate to remove water, and then with a small 
piece of fused potassium hydroxide and red litmus paper ; the latter 
becomes blue in presence of alcohol) may be used for confirmatory 
purposes. In the case of anaesthetic chloroform and commercial chloro- 
form, the amount of alcohol present should be determined by the method 
of Nicloux* as modified by the authors (shaking the chloroform for at 
least ten times in succession with twice its volume of water and using a 

1 Cf.y. Soc. Chem. hid., 1898, 17, 864. - Cf, Ihid., 1896, 15, 748. 

3 Cf. Ihid., 1882, 1, 117. •• Cf. IbiJ., 1906, 25, 611. 



CHLOROFORM 335 

portion of the combined aqueous extracts for the determination), or by 
Behal and Frangois' method.^ 

7. Acetone. — For pure chloroform see (6). For anaesthetic chloroform 
10 c.c. are agitated with 5 drops of a 0-5 per cent, solution of sodium 
nitroprusside and 2 c.c. of ammonia of sp. gr. 0-925, and the mixture 
allowed to stand for several minutes. When acetone is present, 
the supernatant liquid acquires an amethyst colour. The test should 
also be applied to the first 10 per cent, of distillate and the 10 per cent, 
of residue obtained on slowly distilling lOO c.c. of the sample. If the 
proportion of acetone is as low as i : lOOO, the amethyst colour is 
not distinct until the mixture of chloroform with ammonia and sodium 
nitroprusside is saturated with ammonium sulphate, shaken, and then 
allowed to stand for five minutes. In all cases a blank test should be 
made with pure chloroform for comparison. 

8. Acetaldchyde. — With chloroform of all grades, no coloration should 
be produced even after fifteen minutes when 5 c.c. are agitated with 5 
c.c. of Francois' reagent (22 c.c. of sulphurous acid, 30 c.c. of i : 1000 
rosaniline acetate solution, and 3 c.c. of sulphuric acid). For pure 
chloroform, in addition to test (6), no coloration should be produced 
when 5 c.c. are shaken with 5 c.c. of Nessler's reagent and the mixture 
allowed to stand for five minutes. For anaesthetic chloroform, 10 c.c. 
are shaken with 10 c.c. of water and 5 drops of Nessler's reagent, and 
the mixture allowed to stand for five minutes ; no precipitate should 
be produced, and the reagent should not become coloured, although it 
may become opalescent or slightly turbid. 

9. Acidity. — 20 c.c. of the sample are thoroughly agitated with 
10 c.c. of water and 2 drops of phenolphthalein solution, and then 
titrated with N/ioo potassium hydroxide solution ; in the case of either 
pure or anaesthetic chloroform, not more than o-2 c.c. of the alkali solu- 
tion should be required to produce a faint but decided alkaline reaction 
permanent for fifteen minutes, when the mixture is shaken for thirty 
seconds after the addition of each drop of alkali. 

10. Decomposition Products of Pure Chloroform. — A dry stoppered 
tube of 25 c.c. capacity, containing 15 c.c. of the sample, is filled with a 
clear solution of barium hydroxide (1:19) and allowed to stand for three 
hours in the dark, without agitation ; the formation of a film of barium 
carbonate indicates the presence of carbonyl chloride. In addition to 
test (9), both pure and anaesthetic chloroform should comply with the 
following test : — When 10 c.c. are agitated with 5 c.c. of water for five 
minutes, the aqueous extract should not become turbid or give any 
precipitate on addition of silver nitrate solution (absence of hydrochloric 
acid, chlorides, etc.), and no reduction should occur on warming (absence 
of acetaldchyde, formic acid and formates, etc.). With chloroform of all 

1 Cf./. Soc. Cliem. hid., 1897, 16, 566. 



336 ORGANIC PREPARATIONS 

grades, no liberation of iodine, as indicated by addition of starch 
solution, should result when lo c.c. are shaken during fifteen minutes 
with 10 c.c. of a lo per cent, solution of cadmium potassium iodide 
(absence of chlorine and hydrogen peroxide). 

II. Dccoviposition Products of AficBslhelic Chloroform. — For the 
detection of acetaldehyde see (8). If the sample fails to comply with 
test (9) and contains none of the impurities referred to under (10), the 
presence of acetic acid is indicated, and the sample should be rejected. 
For the detection of chlorinated derivatives of the oxidation products of 
alcohol, 20 c.c. of the sample are shaken during twenty minutes with 
15 c.c. of concentrated sulphuric acid, and 2 c.c. of the mixture are 
diluted with 5 c.c. of water ; the liquid should remain colourless and 
clear, and should possess no odour foreign to anaesthetic chloroform 
(chloroform and alcohol) ; it should remain colourless when further 
diluted with 10 c.c. of water, and its transparency should not be 
diminished on addition of 5 drops of silver nitrate solution. 

Quantitative Estimation. 

Chloroform may be estimated either volumetrically by the method 
given by L. de Saint-Martin,^ or iodometrically according to the 
method due to G. Vortmann.^ 

Cinnamic Acid. 

CgHg . CH : CH . COOH. Molec. wt. 148-06. 

Cinnamic acid crystallises in colourless, odourless needles or rhombic 
prisms which melt at 133' and boil at 300° with partial decomposition. 
It dissolves in about 3500 parts of cold water, more readily in boiling 
water, in 4-5 parts of alcohol, in 17 parts of chloroform, and in no parts 
of carbon bisulphide. On warming o-i g. of cinnamic acid in the water- 
bath with 20 c.c. of potassium permanganate solution (i : 1000), a smell 
of benzaldehyde is produced. 

Tests for Impurities. 

Inorganic Matter. — On igniting i g. of cinnamic acid not more than 
0-5 mg. of residue should remain. 

SuIpJiuric and HydrocJdoric Acids. — Neither barium nitrate nor 
silver nitrate solutions should show any reaction with a solution of i g. 
of cinnamic acid in 25 c.c. of boiling water. 

Foreign Organic or Resinous Matter. — On dissolving i g. of cinnamic 
acid in hot sulphuric acid, at most only a light yellow coloration and not 
a brown coloration should result. 

Benzoic Acid. — On thoroughly shaking i g. of cinnamic acid with 

^ CompUs rend., 1888, 106, 492 ; /. Chem. Soc. Aislr., 1888, 54, 570. 

^ Anleiluno zur chemischen Analyse organischer Stoffe, 1891, pp. 102 and 401. 



CHLOROFORM. CITRIC ACID 337 

lOO c.c. of water at 20° at intervals during one hour, and filtering, 50 c.c. 
of the filtrate should not require more than 1-4 c.c. of N/io sodium 
hydroxide for neutralisation, using phenolphthalein as indicator. At 
20°, cinnamic acid is soluble to the extent of i : 2400, and benzoic acid 
of I : 360. Treated as above, benzoic acid yields a filtrate, 50 c.c. of 
which require ii-2 c.c. of N/io sodium hydroxide for neutralisation. 
Traces of benzoic acid in cinnamic acid cannot be detected by this 
method, which only detects quantities over i per cent. 

A sample containing i per cent, of benzoic acid, treated as above, 
requires i-6 c.c. of iV/ 10 sodium hydroxide for neutralisation. According 
to A. W. de Jong^ the benzoic acid in cinnamic acid may be determined 
by converting the cinnamic acid into phen}'ldibromopropionic acid, 
which does not volatilise at loo^ The mixture of the two acids 
(about 2 g.) in carbon bisulphide is treated with bromine, and after 
allowing to stand for twenty-four hours the carbon bisulphide and 
excess of bromine are distilled off; the residue is taken up with ether, 
the ethereal solution evaporated at the ordinary temperature, the 
residue dried m vacuo over sulphuric acid, then powdered and heated 
to loo^ The residual phenyldibromopropionic acid is weighed, and 
the content of benzoic acid thus obtained by difference. By determining 
the bromine in the residual substance and the quantity of sublimed 
benzoic acid, the presence of other substances in the mixture can be 
detected. 

Quantitative Estimation. 

I g. of cinnamic acid is dissolved in 10 c.c. of N\\ sodium hydroxide 
and some water, and titrated with iVyi hydrochloric acid, using phenol- 
phthalein as indicator, i c.c. of sodium hydroxide neutralised corre- 
sponds to 0-1481 g. of cinnamic acid. 

Citric Acid.2 

CgHsOy-t-HgO. Molec. wt. 210-08. 

Citric acid crystallises in large, colourless, rhombic prisms, which 
do not effloresce in dry air at the ordinary temperature, but which lose 
their water of crystallisation completely at 100° ; in a damp atmosphere 
the crystals become moist superficially. The crystallised acid has no 
fixed melting point, since it fuses together at 70°-75°, but the 
anhydrous acid melts at I53''-I54°. Citric acid dissolves in 0-75 parts 
of cold water, in 0-5 parts of boiling water, in i part of alcohol 
(about 85 per cent.), and in about 50 parts of ether. On dissolving 

1 Rec. trav. chim., igog, 28, 342 ; igir, 30, 223 ; /. Soc. C/iem. Ind., 1910, 29, 112; 1911, 
30, 1407. 

- Cf. the section on " Citric Acid," this Vol., pp. 296 et seq. 

Ill Y 



338 ORGANIC PREPARATIONS 

oi g. of the acid in i c.c. of water and adding 40-50 c.c. of lime water 
(the solution must react alkaline), a white flocculent precipitate is 
formed on boiling ; on cooling the solution, the precipitate redissolves 
within three hours. 

Tests for Impurities. 

Inorganic Matter. — I g. of citric acid should leave no appreciable 
residue on ignition. 

Calcium Citrate. — No precipitate should be produced on adding 
ammonium oxalate solution to 20 c.c. of an aqueous solution of the 
acid (i : 10) containing excess of ammonia. 

Lead ; Copper ; Iron. — A solution of 5 g. of citric acid in 10 c.c. 
of water, nearly neutralised with ammonia so that the solution only 
reacts faintly acid (12 c.c. of sp. gr. 096), should remain unchanged on 
treatment with sulphuretted hydrogen. 

Sulphuric Acid. — 20 c.c. of an aqueous solution of citric acid (i : 10) 
should give no turbidity with barium chloride solution. 

Sugar ; Tartaric Acid; Oxalic Acid. — A mixture of i g. of citric acid 
and 10 c.c. of sulphuric acid, prepared in a porcelain mortar previously 
cleaned with sulphuric acid, when heated in a test tube in a boiling 
water-bath for one hour, should not darken and at most only turn 
yellow. 

I g. of citric acid dissolved in 2 c.c. of water should not become 
turbid on the addition of 10 drops of potassium acetate solution and 
5 c.c. of alcohol, and on standing for two hours no crystalline precipitate^ 
should separate.^ 

Quantitative Estimation. 

I g. of crystallised citric acid (with iHoO) requires 14-3 c.c. of N\i 
potassium hydroxide for neutralisation. i c.c. of N\i potassium 
hydroxide corresponds to 007003 g. of citric acid. Phenolphthalein is 
used as indicator. 

Cocaine Hydrochloride. 

Ci,H,iO,N . HCl. Molec. wt. 339-65. 

Cocaine hydrochloride forms colourless, prismatic crystals which 
decompose on melting at 183^ It is readily soluble in water and in 
alcohol. Applied to the tongue, solutions of cocaine hydrochloride 
produce' temporary insensibility. On heating i g. of cocaine h}'dro- 
chloride to about lOO^ for five to ten minutes with 10 c.c. of sulphuric 
acid, and carefully mixing the resulting product with 20 c.c. of water, 

^ For reactions for the detection of tartaric acid in citric acid, c/^ also -l/tvcX'j Reag.-Verz.y 
1908, p. 302. 



COCAINE 339 

the smell of methyl benzoate may be recognised and a considerable 
separation ot benzoic acid occurs. On treating an aqueous solution 
of cocame hydrochloride with a few drops of nitric acid and silver 
nitrate solution, a white precipitate of silver chloride is produced.^ 

Tests for Impurities. 

Inorganic Matter.-Ou igniting 0-5 g. of cocaine hydrochloride not 
more than 0-5 mg. of residue should remain. 

Free Hydrochloric Acid.-An aqueous solution of cocaine hydro- 
chloride should react neutral. 

Cinnamyi Cocaine and Organic Impurities.— According to the British 

Pharmacopoeia a solution containing not less than i per cent of 

cocaine gives a copious red precipitate with an excess of a solution 

ot potassium permanganate which should not change colour within 

an hour. The German Pharmacopoeia prescribes the following test •— 

A solution of o-i g. of cocaine hydrochloride in 5 c.c. of water and 3 

drops of dilute sulphuric acid should assume a violet coloration on the 

addition of 5 drops of potassium permanganate solution (i : 1000) In 

the absence of dust, the coloration should show but little signs of fadin- 

in the course of half an hour. "^ 

Perfectly pure cocaine hydrochloride conforms to the following 

test:— On dissolving o-i g. of cocaine hydrochloride in 5 c.c. of water 

and adding i drop of potassium permanganate solution (i : 1000) the 

pink coloration should not fade within fifteen minutes. As a standard 

for comparison, i drop of potassium permanganate is added to :; cc of 

water. 

It is of importance that the test tubes used for the above reactions 
are scrupulously clean. 

Foreign Alkaloids.-On adding 10 drops of 3 per cent, chromic acid 
solution to an aqueous solution of cocaine hydrochloride (o-i : 10) the 
addition of each drop produces a yellow precipitate which redissolves 
immediately; on the addition of 2 c.c. of hydrochloric acid (sp gr 
1-124) the precipitate is reformed. ^ i- & • 

G. L. Schaefer^ has proposed the following test, based on the 
relative greater solubility of cocaine chromate as compared with 
that of the chromates of the other coca bases, in presence of 
hydrochloric acid :— 0-05 g. of cocaine hydrochloride is dissolved in 
20 C.C. of water, 5 c.c. of a 3 per cent, chromic acid solution and 
5 cc. of 10 per cent, hydrochloric acid (at 15°) added; if the cocaine 
hydrochloride is pure, the solution remains clear, and the more foreign 
coca bases are present the greater is the turbidity produced. The 

1 For identifying reactions, cf. Merck's Reag.-Verz., 1908, p. 29J. 

2 pi,ar,n.J., 1899, 69 [1503]. 336; 1899, 63 [1517], 66; /. Soc. Chem. Ind., 1899, 18 
532, 790. "' ' 



340 ORGANIC PREPARATIONS 

value of this reaction has been adversely criticised by P. W. Squire^ 
and by E. Merck.- 

MacLagaris Test. — o-i g. of cocaine hydrochloride is dissolved in 
lOO c.c. of water, and o-2 c.c. of ammonia (sp. gr. 096) added ; on 
vigorously scratching the sides of the glass vessel with a glass rod, a 
flocculent crystalline precipitate is formed within ten minutes without 
any milky turbidity being produced in the liquid ; the latter should 
remain quite clear.^ 

This test is prescribed as follows by the British Pharmacopceia : — 
o-i a-, of cocaine dissolved in 100 c.c, of water and 0-25 c.c. of a solution 
of ammonia added, affords a clear solution from which a crystalline 
precipitate should gradually separate on stirring. 

The German Pharmacopoeia gives the following modification of this 
test: — If a solution of o-i g. of cocaine hydrochloride in 80 c.c. of water 
is carefully mixed, without shaking, with 2 c.c. of a mixture of i part 
of ammonia (10 per cent.) and 9 parts of water, no turbidity should 
become apparent within half an hour. On scratching the sides of the 
(^lass vessel with a glass rod, the above-mentioned separation of crystals, 
etc., should then take place. 

Oro-anic Matter ; Sugar ; Foreign Alkaloids. — Cocaine hydrochloride 
should produce colourless solutions when dissolved in nitric and in 
sulphuric acids in the proportion of i -.10, 

Water. — No appreciable loss in weight should take place on drying 
cocaine hydrochloride at 100°. The British Pharmacopoeia prescribes 
that the salt should not lose more than i per cent, of moisture when 
dried for twenty minutes at 95''-6-ioo''. 

Cocaine hydrochloride may be estimated volumetrically in alcoholic 
solution, using Poirrier's blue as indicator, as described for quinine 
hydrochloride (p. 381). i c.c. of N\^ potassium hydroxide corresponds 
to 006793 g. of cocaine hydrochloride. 

Coumarin. 

yO — CO 
CeH/ I . Molec. wt. 14605. 

^CH = CH 

Coumarin forms white, glistening, small, leafy crystals, and possesses 
a characteristic smell. It; is sparingly soluble in cold water (about 
I : 400), more readily in boiling water (about i : 45), and very soluble 

1 Chem. and Drug., 1899, 54, 64 1. 

2 Pharm.J., 1899, 62 [l5"]. 523 ; /• Soc. Chem. bid., 1899, 18, 713. 

3 For further details of the MacLagan test, cf. Gunlher, I'/iarm. Zentralh., 1899, p. 186 ; E. 
Merck, Pliarm. Zeit., 1899,44. 367;/. Soc. Chem. Ind., 1899, 18, 713; C. Boehringer, Chem. 
aii'i Druji., 1899, 55, 59 ; Zimmer & Co., Pharm. Zeit., 1899, 66, $83 ; /. ^oc. Chem. /;/</., 1899, 
18, 1055; B. H. Paul and A. J. Cownley, Pharm. J., 1899, 62 [15"]. 524- 



COUMARIN. DEXTROSE 341 

in alcohol and in ether; melting point 6f', boiling point 291°. On 
fusing coumarin with potassium hydroxide, salicylic and acetic acids are 
formed, which may be readily identified. 

Tests for Impurities. 

Vanillin. — No coloration should be produced on heating 0-2 g. of 
coumarin with a mixture of 5 c.c. of phenol and 3 c.c. of sulphuric acid 
at i6o°-i70° for several minutes; vanillin gives a blood-red or very 
dark red coloration.^ 

Organic Impurities. — A colourless solution should be formed on 
dissolving i g, of coumarin in 10 c.c. of sulphuric acid. 

Inorganic Impurities. — On ignition, i g. of coumarin should not leave 
more than 0-5 mg. of residue. 

Acetanilide. — 0-2 g. of coumarin is boiled for one minute with 2 c.c. 
of hydrochloric acid, and then 4 c.c. of phenol solution (i : 20) together 
with a filtered solution of calcium hypochlorite added ; no violet 
coloration should be produced. The latter would be formed in presence 
of acetanilide, in which case the colour of the mixture would be changed 
to indigo-blue on the further addition of ammonia. The acetanilide 
may be most simply estimated by determining the nitrogen by 
Kjeldahl's method, provided that no other substances containing 
nitrogen are present.- 

Dextrose. 

QHiPc- Molec. wt. i8o-io. 

CoHiPg+HoO. Molec. wt. 198-11. 

Anhydrous dextrose consists of small, white, odourless prisms, joined 
together to form warty masses, or of a white crystalline powder. It has 
a sweet taste, the degree of sweetness being less than half that of cane 
sugar. Dextrose containing water of crystallisation forms white, 
granular, crystalline masses. The anhydrous substance melts at 146'^, 
the hydrated at about 85°. The specific rotatory power of the anhydrous 
dextrose is [a]D=52-5; that of the hydrated form [ajo =477. The 
so-called anhydrous dextrose of commerce generally contains small 
quantities of water, which lower the melting point. Dextrose is very 
soluble in water, almost insoluble in cold alcohol, but more so in boiling 
alcohol. 

Dextrose reduces alkaline copper and bismuth solutions, ammoniacal 
silver solution, and copper acetate solution on warming.^ 

1 Cf. Merck's Reag.-Verz,, 1908, p. 1 3 3. 

2 For the detection, separation, and identification of coumarin and vanillin in commercial 
extracts, cf. Z. anal. Chem., 190^, 43, 263. 

' For reactions of dextrose, cf. Merck's Reag.-Verz., 1908, p. 294. 



342 ORGANIC PREPARATIONS 

Tests for Impvirities. 

Inorganic Matter. — On ignition, 5 g. of dextrose should not leave 
more than 0-5 mg. of residue. 

SulpJuiric Acid. — An aqueous solution of dextrose (i : 10) should 
give no reaction with barium chloride solution. 

Hydrociiloric Acid. — No precipitate, but at most onl}' a faint 
opalescence, should be shown on adding a few drops of nitric acid and 
silver nitrate solution to an aqueous solution of dextrose (i : 10). 

Cane Sugar.— A colourless solution should be produced on dissolving 
I g. of dextrose in 10 c.c. of sulphuric acid at 15"; only a pale yellow 
coloration should result on standing for a quarter of an hour. 

Dextrin. — i g. of dextrose should dissolve completely in 20 c.c. of 
boiling 90 per cent, alcohol without leaving any insoluble residue. An 
aqueous solution of dextrose (i : 10) should not turn a reddish colour 
on the addition of a very dilute iodine solution. 

Quantitative Estimation. 

The water in dextrose is determined by drying at 100° till constant. 

Dextrin in impure dextrose is determined indirectly by estimating 
the content of dextrose, of water, and of ash, and calculating the dextrin 
by difference; or, the dextrose is determined before and after inversion, 
and the dextrin calculated from the difference. 

The content of dextrose may be arrived at by various methods : — - 

1. By measuring the polarisation of the aqueous solution.^ 

2. From the specific gravity of the aqueous solution.- 

3. By the reducing action on Fehling's solution, either using a 
volumetric method or by weighing the cuprous oxide. 

Details of these methods are described in the sections on " Sugar " 
(pp. 554 et seq.) and " Brewing Materials and Beer" (pp. 824 et seg.). 

The following volumetric method by E. Riegler^ is simple and 
satisfactory. 

This method is based on the estimation of the copper in a known 
volume of Fehling's solution before and after the reduction by means 
of dextrose, the copper being estimated iodometrically according to the 
equation : — 

2CUSO4+4KI = 2K.SO, + CuJ.,+ l2. 

A copper solution is prepared (69-28 g. of crystallised copper 
sulphate to the litre), as well as a solution of Rochellc salt (346 g. of 
Rochelle salt and 100 g. of sodium hydroxide to the litre), the former 
being standardised as follows : — 10 c.c. of the copper solution, 10 c.c. of 

' Landolt, Ber., 1888, 21, 191 ; Z. anal. Chem., 1889, 28, 203. 

2 Z. ana!. Chem.^ 1883, 22, 454. 

' Z. anal. Chem., 1898, 37, 22 ; /. Soc. Chem, Ind., 1898, 17, 499. 



DEXTROSE 343 

the Rochelle salt solution, lOO c.c. of water, and 2 c.c. of pure con- 
centrated sulphuric acid are well mixed in a 200 c.c. flask, 10 c.c. of a 
10 per cent, aqueous solution of potassium iodide added, and the 
contents of the flask well mixed. In the course of about ten minutes 
starch solution is added and the free iodine titrated with iV/io sodium 
thiosulphate, until the blue colour disappears and does not return on 
standing for five minutes ; a return of the blue colour after standing- for 
over five minutes is disregarded. Each cubic centimetre of thiosul- 
phate solution corresponds to 0-00635 g. of copper. If the solutions 
have been correctly prepared, 10 c.c. of the copper solution will require 
27-8 c.c. of the thiosulphate solution, and the quantity of copper found 
will be, therefore, 27-8 x 0-00635 =0-1765 g. If more or less than 
27-8 c.c. be required, the volume found must be used as a factor in 
place of 27-8, 

To carry out the estimation, 10 c.c. of the copper solution, 10 c.c. 
of Rochelle salt solution, and 30 c.c. of water are heated to boiling in a 
200 c.c. beaker, and 10 c.c. of a solution of dextrose, not stronger 
than I per cent, are run in. The mixture is kept boiling for some 
time, after which the precipitate is allowed to settle, the solution filtered 
(using the pump) through an asbestos filter, and the precipitate washed 
with about 80 c.c. of water. The filtrate is washed out into a 200 c.c. 
flask, 2 c.c. of sulphuric acid added, then 10 c.c. of potassium iodide 
solution, and after standing for ten minutes starch solution is added 
and the iodine titrated with thiosulphate solution as above. 

If V represents the number of cubic centimetres of thiosulphate 
solution used, then the quantity of copper reduced by the sugar is 
= (27-8 — V) X 0-00635. 

Diethyl Barbituric Acid. (Veronal.) 

,C0— NH- 
(C2H5).3C< >C0. Molec.wt. 184-12. 

\C0— NH/ 

Diethyl barbituric acid or veronal is a white, crystalline powder with 
a somewhat bitter taste, soluble in about 145 parts of cold or in 12 
parts of boiling water. It is readily soluble in ether, acetone, ethyl 
acetate, hot alcohol, and alkalis, but is only sparingly soluble in 
chloroform and glacial acetic acid. The aqueous solution reacts faintly 
acid with litmus paper. Melting point 191°. The addition of a few 
drops of nitric acid and several drops of Millon's reagent to a solution 
of 0-05 g. of veronal in 10 c.c. of water produces a white gelatinous 
precipitate which redissolves on adding a large excess of the pre- 
cipitant. Ammonia is evolved on boiling o-i g, of veronal with 5 c.c. 
of potassium hydroxide solution. 



344 ORGANIC PREPARATIONS 

Tests for Impurities. 

Hydrochloric and SulpJiuric Acids. — Neither barium nitrate nor 
silver nitrate solution should produce a precipitate with a solution of 
o-i g. of veronal in 20 c.c. of water. 

Organic Impurities. — Veronal should dissolve in sulphuric acid to a 
colourless solution. It should not become coloured on shaking with 
nitric acid. 

Inorganic Impurities. — o-i g. of veronal is placed on the lid of a 
platinum crucible and heated on an asbestos plate. The preparation 
should sublime, leaving only very little carbon behind. On ignition, 
no appreciable residue should be left. 

Veronal-Sodium. 

C.,H. CO . NXa 

\C<; /CO. Molec. wt. 206-II. 

C.2H/ \CO.NH / 

This is a white, crystalline powder with a bitter taste, and is verj'- 
soluble in water (i : 5). The aqueous solution reacts alkaline. Mineral 
acids as well as acetic acid produce a voluminous white precipitate 
when added to a concentrated aqueous solution (i : 5). 

Veronal-sodium may be titrated with A^/io hydrochloric acid, using 
either methyl orange or Congo red as indicator.^ 

Ethyl Acetate. 
CH3 . COOC2H5. Molec. wt. 88-06. 

Ethyl acetate is a colourless, volatile liquid with a characteristic 
refreshing smell. It is miscible in all proportions with alcohol, ether, 
benzene, and chloroform, and with 17 parts of water. 

Ethyl acetate, when quite pure and free from water and alcohol, 
has a sp. gr. of 0-9254 at 0° compared with water at 4° (J. Wade and 
R. W. Merriman ■-), and boils at yf. The pure commercial product, 
which also is used in medicine, has a sp. gr, of 0-900-0-904 and boils 
at 74''-78^ ; it contains traces of water and alcohol. 

Tests for Impurities. 

Inorganic and non-volatile Organic Matter. — No residue should be 
left on evaporating 50 c.c. of ethyl acetate on the water-bath. 

Fi-ee Acid {Acetic Acid). — A piece of blue litmus paper placed in 
ethyl acetate should not be immediately reddened. 

' For further details concerning veronal, cf. Pliartn. Zoitial/i., 1908, p. 104 1. 
'^ J. Chcm. Soc.^ 1912, lOl, 2429. 



ETHYL ACETATE 345 

Ainyl Compounds and Ethyl Butyrate. — On pouring ethyl acetate 
over filter paper and allowing it to evaporate at the ordinary tempera- 
ture, it should not be possible to detect the smell of foreign esters after 
the smell of the eth)'l acetate ceases to be noticeable. 

Amyl Alcohol and Organic Impurities. — On pouring a few cubic 
centimetres of ethyl acetate carefully on to sulphuric acid, no coloration 
should be produced at the zone of contact of the two layers of liquid. 

Water and Alcohol. — On thoroughly shaking 25 c.c. of ethyl acetate 
with 25 c.c. of a saturated solution of calcium chloride for one minute, 
no appreciable increase in the volume of the latter should take place. 

Note. — On shaking ethyl acetate with water, the volume of the 
latter increases from 2-2-5 c.c, owing to the water taking up some ethyl 
acetate ; on the other hand, ethyl acetate also takes up water. The use 
of a cold, saturated solution of calcium chloride allows of a better 
estimation of the content of water and of alcohol being made, since the 
latter are completely taken up by the calcium chloride solution. A 
turbidity produced on dissolving in benzene will indicate if more than 
a permissible quantity of water is present. i c.c. of ethyl acetate 
should dissolve to a clear solution in 10 c.c. of benzene. Ethyl acetate 
quite free from water will also dissolve to a clear solution in official 
paraffin oil (liquid paraffin). 

The content of alcohol is determined in the same manner as described 
for ethyl butyrate (see p. 349). 

Ethyl Alcohol. 
C2H5 . OH. Molec. wt. 46-05. 

Two kinds of ethyl alcohol come under consideration for technical 
purposes : the so-called " Absolute Alcohol " and " Rectified Spirit " ; 
from the latter, various mixtures with water are prepared, such as the 
70 per cent, 60 per cent., 45 per cent., and 20 per cent, spirit of the 
British Pharmacopoeia. 

The qualitative examination of these varieties may be made in the 
same manner, without reference to the differences in the content of 
alcohol. 

Absolute alcohol is a colourless, neutral liquid boiling at 7^"-^ ; the 
specific gravity, according to the determinations of Mendeleff, is 
0-79367 at 1574°- A good commercial product should contain not 
less than 99-11 per cent, by weight of alcohol and have a sp. gr. 
of not over 0-797. A guarantee of 100 per cent, can never be given, 
since 100 per cent, alcohol is very hygroscopic. 

Rectified spirit should contain at least 94-38 per cent, by weight, and 
96-37 per cent, by volume of alcohol and have a sp. gr, not higher 
than 0-81 1. The "Rectified Spirit" of the British Pharmacopoeia 



346 ORGANIC PREPARATIONS 

has a sp, gr. of 0S340 and contains 85-65 per cent, by weight of ethyl 
alcohol. 

Tests for Impurities. 

Fusel Oil. — No turbidity and no smell foreign to alcohol should be 
produced on mixing 10 c.c. of alcohol with 30 c.c. of water in an 
Erlenmeyer flask. On rubbing a few drops of the sample between 
the hands, no unpleasant smell (fusel oil) should be noticeable after the 
evaporation of the alcohol. On the addition of 25-30 drops of a 
I per cent, alcoholic solution of salicyl aldeh)-de and 20 c.c. of con- 
centrated sulphuric acid to a mixture of 5 c.c. of alcohol and 5 c.c. of 
water, and cooling the mixture, a lemon-yellow coloration is produced 
if the alcohol be free from fusel oil. If only traces of fusel oil are 
present, the solution will appear yellow by transmitted light and red 
by reflected light. In no case should the colour be reddish or red. 

If a mixture of 10 c.c. of alcohol and 02 c.c. of 1 5 per cent, potassium 
hydroxide solution be evaporated down to i c.c. on the water-bath, 
there should be no smell of fusel oil on adding excess of dilute 
sulphuric acid. 

Acetone. — On shaking a mixture of 2 c.c. of alcohol, 6 c.c. of baryta 
water, and 6 drops of mercuric chloride solution (i : 20) for one minute 
and filtering, the filtrate should not be darkened by the addition of 
ammonium sulphide solution. 

Aldehyde. — A mixture of 10 c.c. of alcohol, 10 c.c. of water, and 2 c.c. 
of ammoniacal silver solution (prepared by mixing 10 c.c. of 5 per cent.- 
silver nitrate solution with 5 c.c. of ammonia of sp. gr. 0-96), allowed to 
stand in the dark at the ordinary temperature for fifteen hours, should 
become neither coloured nor turbid. 

Ftirfural{^Fjirfuraldehyde\ — A mixture of 10 c.c. of alcohol, 5 drops 
of acetic acid (sp. gr. 1-040- 1-042), and i drop of aniline, as colourless 
as possible, should not turn red in the course of one hour. 

Molasses Spirit. — On pouring 5 c.c. of alcohol carefully over 5 c.c. of 
concentrated sulphuric acid, no rose-coloured ring should be produced 
at the point of contact of the two layers of liquid. 

Metals atul Tannin. — No coloration should be produced on adding 
either i c.c. of ammonia (sp. gr. 0-96) or 5 c.c. of sulphuretted hydrogen 
water to 10 c.c. of alcohol. 

Inorganic Matter. — No appreciable residue should remain on slowly 
evaporating 50 c.c. of alcohol. 

Methyl Alcohol. — If a negative result has been obtained when 
testing for acetone, it may be taken for granted that the alcohol 
contains no crude wood spirit. 

For the independent detection of methyl alcohol in ethyl alcohol, a 
number of methods have been proposed, based on the oxidation of the 



ETHYL ALCOHOL 347 

methyl alcohol to formaldehyde and the subsequent identification of the 
latter. A critical summary of the various methods has been given by 
A. Vorisek,^ who recommends oxidation with potassium bichromate 
and sulphuric acid and testing the distillate obtained for formaldehyde 
by the addition of ferric chloride and albumin solutions in presence of 
concentrated sulphuric acid, when a sharply defined violet-coloured zone 
is formed at the junction of the liquids. 

Quantitative Estimation. 

The content of alcohol is practically always determined by means 
of the specific gravity, specially prepared Tables being employed of 
which those of the Excise Authorities constitute the legal standard in 
this country. A full description of this estimation is described under 
the heading " Alcoholometry," in the section on " Alcohol, Potable 
Spirits, and Liqueurs," this Vol., p. 709. 

Should it be desired to carry out an estimation of ethyl alcohol by 
a chemical method, that given by O. Blank and H. Finkenbeiner^ for 
methyl alcohol is to be recommended, since it is also quite suitable for 
the estimation of ethyl alcohol. An excess of A710 potassium 
bichromate solution and sulphuric acid are added to the very dilute 
aqueous solution of the alcohol, and after standing at the ordinary 
temperature for some hours, potassium iodide is added and the mixture 
titrated back with A710 sodium thiosulphate solution. The oxidation 
takes place according to the equation : — 

CH3.CH2OH + O2 = CH3.C00H + H,0. 

A reliable method for the quantitative estimation of methyl alcohol 
in ethyl alcohol, based on the oxidation of the former to carbon dioxide, 
has been worked out by T, E. Thorpe and J. Holmes,^ (See p. 717.) 

Ethyl Bromide. 

CoHsBr. Molec. wt. 108-96. 

Ethyl bromide is a clear, colourless, strongly refractive, ethereal 
smelling liquid with a sp. gr. of I-453-I-457, and boiling at 38°-40°. 
Perfectly pure ethyl bromide has a sp. gr. of 1-4735 and boils at sS'^-39'^. 
Since the pure product readily turns yellow through decomposition, 
about I per cent, of alcohol is added to render the commercial product 
less liable to decomposition. 

1 /. Soc. Chem. Ind., 1909, 28, 823. Cf. also C. Deniges, Bull. Soc. Chim., 1910, 7, 951 ; /. 
Soc. Chem. Ind., 1910, 29, 1325, and Merck's Reag.-Verz., 1908, p. 297. 

2 Ber., 1906, 39, 1326 ; J. Soc. Chem. Ind., 1906, 25, 500. 

3 For estimating ether and benzene in alcohol, c/. H. Wolff, Chem. Zeit., 1910, 34, I193; 
J. Soc. Chem. Ind., 1910, 29, 1403, and for estimating carbon bisulphide in alcohol, W. Schmitz- 
Dumont, Chem. Zeit., 1897, 21, 487 and 510 ; /. Soc. Chem. Ind.^ 1897, 16, 829. 



348 ORGANIC PREPARATIONS 

Tests for Impurities. 

Inorganic and non-volatile Organic Matter. — Not more than i mg. 
of residue should remain on evaporating 20 c.c. of ethyl bromide on the 
water-bath. 

Pliosplionis Conipoujids. — No unpleasant garlic-like odour should be 
recognisable on evaporating 5 c.c. of ethyl bromide in a small porcelain 
dish.i 

Hydrobroinic Acid. — Ethyl bromide should react neutral. On 
shaking 10 c.c. with 10 c.c. of water for a few seconds, pouring off 5 c.c. 
of the aqueous layer and adding 2 drops of A710 silver nitrate solution, 
no turbidity should be produced within five minutes. The ethyl 
bromide should not be shaken up directly with silver nitrate solution, 
since silver bromide is always thus formed. 

Aviyl Compounds, Ethylene didromide, Organic SulpJiur Compounds. — 
10 c.c. of ethyl bromide are well shaken during one hour with 10 c.c. of 
sulphuric acid in a stoppered glass cylinder previously rinsed out with 
sulphuric acid. No yellow coloration of the sulphuric acid should be 
produced. 

EtJiyl Ether. — A possible content of ether is indicated by a too low 
specific gravity. It is stated that commercial ethyl bromide may 
contain up to 15 per cent, of ether.^ 

Ethyl Butyrate. 

C3H, . COOC0H5. Molec. wt. 1 16- 10. 

Eth}-1 butyrate is a colourless liquid, sparingly soluble in water but 
readily so in alcohol, ether, benzene, chloroform, and petroleum spirit. 
In the diluted state it possesses a pleasant smell and tastes of pine 
apple. Its sp. gr. is 0-884, and it boils at 11 8'- 120''. 

Tests for Impurities. 

Inorganic aiid non-volatile Organic Matter. — 10 c.c. of eth}-l butyrate 
should not leave more than 0-5 mg. of residue on evaporation. 

Hyd7-ochloric and Sulphuric Acids. — On shaking 20 c.c. of eth\-l 
butyrate with 10 c.c. of water, the separated water should show no 
reaction with cither silver nitrate or barium chloride solutions. The 
test cannot be made with litmus paper, since the water ahva}-s reacts 
acid owing to liberated butyric acid. 

Water. — Ethyl butyrate should dissolve without turbidity in ten 
times its volume of benzene. Chemically pure ethyl butyrate, absolutely 
free from water and alcohol, mixes also with petroleum spirit (boiling 

1 Cf. Chem. Zeit. Rep., 1908, 32, 638. - Pharm, Zentialh., 35, 674. 



ETHYL BUTYRATE 349 

point 50°-75^) and official paraffin oil (liquid paraffin) to form quite 
clear solutions. 

Alcohol — On shaking 20 c.c. of ethyl butyrate with 20 c.c. of a 
saturated solution of calcium chloride, and allowing the two liquids to 
separate completely, no change in volume of the calcium chloride 
solution should take place. 

Quantitative Estimation. 

Ethyl butyrate comes into commerce in alcoholic solution, the 
product being known as " pine-apple oil." The content of the ester in 
such products may be sufficiently accurately estimated by shaking with 
a proportionately large volume of saturated calcium chloride solution. 

The accurate estimation of the alcohol and of the ester, in either 
concentrated or dilute commercial varieties, is carried out as follows : — 
25 g. of the ester are heated with a solution of 22 g. of potassium 
hydroxide in 40 c.c. of water in a 200-250 c.c. Jena glass flask fitted with 
an upright condenser, until the saponification is complete. In the case of 
products containing a high percentage of ester, complete saponification is 
indicated by the original two layers of ester and of potassium hydroxide 
disappearing to form one homogeneous straw-coloured solution. The 
mixture is then further boiled for about half an hour. In the case of 
products of low ester content {i.e., mixtures containing a little ester and 
much alcohol), after the disappearance of the two layers of liquid, the 
mixture is further boiled vigorously for one hour. The saponification 
should be carried out over the free flame, or over a wire gauze. The con- 
tents of the flask are then allowed to cool, about 60 c.c. of water washed 
down the upright condenser into the flask, and 100 g. of the mixture 
then distilled off, using an ordinary condenser and a condensation bulb 
between the flask and condenser, and taking care that no alkali spirts over, 
and that no alcohol is lost by evaporation. From the specific gravity of 
the distillate its alcohol content can be calculated, and from this value 
the alcohol content in the ester in percentage by weight. Having thus 
determined the free alcohol together with the alcohol combined with the 
butyric acid, the content of combined alcohol, from which the content 
of pure ester may be calculated, is determined by saponifying a weighed 
quantity of the ester with an excess of iV/2 potassium hydroxide, and 
titrating back with A^/2 hydrochloric acid, using phenolphthalein as 
indicator, i c.c. of N\2 potassium hydroxide corresponds to 0-05805 g. 
of butyric ester, or to 0-04605 g. of combined alcohol. 

The difference between the total alcohol and the combined alcohol 
gives the quantity of free alcohol. All the necessary data may be, 
therefore, obtained by making the above two estimations, from which 
the content of pure ester, of alcohol, and of water are calculated. 



350 ORGANIC PREPARATIONS 

Ethyl Ether. 

CoH- . O . CoH.. Molec. \vt. 74-08. 

Ether is a colourless, mobile, and readily inflammable liquid, posses- 
sing a characteristic smell. It boils at 34°-36°, and has a sp. gr. of 0720. 
Ordinary commercial ether has a sp.gr. of 0725, owing to its containing 
small quantities of water or of alcohol. Ether used for the quantitative 
estimation of fat, in the analysis of alkaloids, and for anaesthetic 
purposes, should have a sp. gr. of not more than 0720-0722. The 
ether of the British Pharmacopoeia has a sp. gr. of 0735, and contains 
not less than 92 per cent, by volume of pure ether. 

Tests for Impurities. 

Residue. — On allowing 20 c.c. of ether to evaporate spontaneously in 
a glass dish, covered with an inverted funnel, the residue remaining on 
the sides of the dish should have no smell, should not redden or bleach 
blue litmus paper, and on warming on the water-bath should evaporate 
completely, leaving no residue. 

Water. — On shaking 20 c.c. of ether with i g. of dehydrated copper 
sulphate, the latter should not acquire either a green or blue colour. 

A method for the quantitative estimation of water in "wet" ether 
based on the insolubility of cadmium iodide in anhydrous ether, has 
been worked out by D. Tyrer.^ 

Hydrogen Peroxide, Ozone, Ethyl Peroxide. — On shaking 10 c.c. of 
ether with i c.c. of potassium iodide solution (i : 10) in a full, closed,- 
glass-stoppered vessel, in the dark, neither the potassium iodide solution 
nor the ether should become coloured at the end of one hour. 

A very sensitive reaction for peroxides is the following : — o-i g. of 
pure, powdered vanadic acid is heated for a quarter of an hour on the 
water-bath with 2 c.c. of concentrated sulphuric acid, and then 50 c.c. of 
water added. This reagent has a yellow colour. On shaking 20-30 c.c. 
of ether with 2 c.c. of this reagent, the smallest traces of peroxide 
present will immediately turn the colour of the latter to brown or 
reddish-brown. 

Aldehyde and Vinyl Alcohol — On shaking 20 c.c. of ether for one 
minute in a glass-stoppered cylinder with 5 c.c. of Nessler's reagent, no 
reddish-brown precipitate, soon turning to black, should be produced.- 

Acetone. — A mixture of 6 c.c. of baryta water and 6 drops of 5 per 
cent, mercuric chloride solution are shaken for one minute with 20 c.c 
of ether, and the aqueous solution separated and filtered. The latter 
should show no dark coloration during ten minutes after the addition of 
ammonium sulphide. 

1 /. Chem. Soc. Proc, 1911, 27, I42 ; /. Soc. Chem. hid., I911, 30, 767. 

2 Cf. Wobbe, Apolh. Zeit., 1903, p. 466. 



ETHYL ETHER. FORMALDEHYDE 351 

Sulphur Compounds. — On shaking 20 c.c. of ether with a drop of 
mercury in a glass bottle for two minutes, the surface of the mercury 
should show no change, and no black substance should be separated. 

Alcohol — A test for alcohol is not necessary should the ether possess 
the correct specific gravity ; a Table giving the specific gravities of 
mixtures of alcohol and ether has been prepared by E. R. Squibb.^ 
According to Lieben, the presence of alcohol may be detected by the 
iodoform reaction. The ether is shaken up with water, and the aqueous 
solution warmed, after the addition of sodium hydroxide and iodine 
solutions ; the formation of iodoform indicates the presence of alcohol. 

Formaldehyde. 

H . CHO Molec. wt. 3002. 

Formaldehyde is a colourless liquid with an irritating smell, and is 
miscible in all proportions with water and alcohol. The specific gravity 
of the commercial product varies from i -08- 1-095 according to the 
content of formaldehyde and of methyl alcohol, and the content of 
formaldehyde varies fropri 30-40 per cent. The purest commercial 
product is that used for medicinal purposes. The German Pharma- 
copoeia gives the sp. gr. of i -079-1 -08 1 with about 35 per cent, of 
formaldehyde. The specific gravity alone gives no reliable indication 
as to the content of formaldehyde, since the commercial product always 
contains some methyl alcohol which lowers the specific gravity. The 
40 per cent, formaldehyde contains up to 20 per cent, of methyl 
alcohol. In preparations containing less methyl alcohol, there is always 
the possibility of paraformaldehyde separating out at somewhat low 
temperatures.^ 

The methods for the estimation of methyl alcohol in formaldehyde 
are fully described in the section on " Organic Dyes," Vol. IL, Part II., 
pp. 911 ^/ seq. 

Formaldehyde reduces ammoniacal silver solution and Fehling's 
solution and gives a deep red coloration with Schiff s reagent ; an 
ammoniacal formaldehyde solution gives a white precipitate with 
bromine water (hexamethylenetetramine bromide). On evaporating 
formaldehyde on the water-bath a white amorphous mass (trioxy- 
methylene) is left, which is insoluble in water, and which is completely 
volatile on ignition. On making formaldehyde strongly alkaline with 
ammonia, and heating the mixture on the water-bath, a white crystal- 
line residue (hexamethylenetetramine) remains, which is readily soluble 
in water. Other reactions that can be used for the quantitative deter- 

1 Phartn. J., 1 884, p. 74 ; /. Soc. C/iem. Ind., 1884, 3, 53 1. Cf. also Z. anal. Chem., 1889, 

26,97. 

2 Cf. Merck's Jahresber., 1903, p. 79. 



352 ORGANIC PREPARATIONS 

mination of formaldehyde are described in the section on " Organic 
Dyes," Vol. II., Part II., pp. 898 et seq. 

Tests for Impurities. 

Free Acid. — 10 c.c, of formaldehyde should not react acid after the 
addition of 10 drops of N\\ potassium hydroxide. Formaldeh}-dc 
sometimes contains up to o-2 per cent, of formic acid. 

Hydrochloric Acid. — Formaldehj-de should, at most, only give a 
slight opalescence on the addition of silver nitrate solution, and when 
diluted with four times its volume of water should give no reaction 
with this reagent. 

Sulphuric Acid. — Formaldehyde should .show no reaction with 
barium chloride solution. 

Heavy Metals. — On the addition of sulphuretted hydrogen water, 
formaldehyde should not be discoloured. Commercial products some- 
times contain up to o-oi per cent, of cupric oxide, in which case the 
above test will not be negative. 

Inorganic Salts.— Not more than i mg. of residue should remain on 
evaporating 10 c.c, of formaldehyde and igniting with free access of 
air. The purest formaldehyde often contains minute traces of iron. 

Quantitative Estimation. 

The methods for the quantitative estimation of formaldehyde are 
described in the section on "Organic Dyes," Vol. II., Part II., pp. 
90 1 et seq. 

Formic Acid. 

n . COOH. Molec. wt. 4602. 

Formic acid is a colourless liquid with an irritating smell. It has a 
sp. gr. of 1-22 at 20 , boils at 100 -6, and melts at 8-6. It is miscible in 
all proportions with water and alcohol. Sulphuric acid decomposes it 
into carbon monoxide and water. On warming an aqueous solution of 
formic acid (i : 10) with silver nitrate, metallic silver separates out; 
warmed with mercuric chloride, mercurous chloride is precipitated ; and 
on warming with yellow mercuric oxide, a colourless solution is first 
formed from which, on further heating, carbon dioxide is evolved with 
separation of metallic mercury. 

Tests for Impurities. 

Inorganic Matter. — Not more than 05 mg. of residue should be left 
on evaporating 5 g. of formic acid. 

Leady Copper, Iron. — Sulphuretted hydrogen water should produce 
no change in a solution of formic acid (i : 20) rendered alkaline by 
ammonia. 



FORMIC ACID. GALLIC AClD 35^ 

Hydrochloric mid Oxalic Acids. — Neither silver nitrate solution at 
the ordinary temperature nor calcium chloride solution, the latter being 
added to a solution made alkaline with ammonia, should produce any 
change in an aqueous solution of formic acid (i : 20). 

Acetic Acid. — If i c.c. of formic acid is warmed on the water-bath 
with 20 c.c. of water and 6 g. of yellow mercuric oxide, and frequently 
shaken until no further evolution of gas takes place on filtering, the 
filtrate should not react acid. 

Acrolein^ Ally I Alcohol, Enipyreumatic Matter. — No irritating or 
burning smell should be given off on saturating formic acid with excess 
of sodium hydroxide solution. 

Since formic acid comes into commerce in various degrees of 
dilution, the content of formic acid should first be determined by 
titration withiV/l sodium hydroxide solution, and the foregoing tests 
then carried out with suitable quantities proportional to the degree 
of dilution of the acid. 

Quantitative Estimation. 

Formic acid is estimated in aqueous solution by titration with N\i 
sodium hydroxide, using 'phenolphthalein as indicator, i c.c. of iV/i 
sodium hydroxide corresponds to 0-046016 g. of formic acid. Since 
this simple titration gives no guarantee that only the formic acid 
is estimated, it is better to use the method worked out by H. Franzen 
and G. Greve, as described in the section on "Organic Dyes," Vol. II., 
Part II., p. 917. Other quantitative methods are described in the 
same section.^ 

Gallic Acid. 
C6H2(OH)3.COOH + H.p. Molec. wt. 18806. 

Pure gallic acid comes into commerce as colourless or pale yellow 
coloured needles or prisms, which possess an acid, astringent taste, 
and which melt at 220", undergoing slow decomposition. 

Gallic acid dissolves in 85 parts of water at 15° and in 3 parts 
of boiling water, in 6 parts of alcohol and in 10 parts of glycerol. 
It is only sparingly soluble in pure ether, but the solubility increases 
with an increase in the proportion of alcohol contained in the ether used. 

A bluish - black precipitate is produced on adding ferric chloride 
to a solution of gallic acid. On standing in the air, an aqueous 
solution of the acid, to which excess of alkali is added, turns reddish- 
brown to black. Potassium cyanide colours the aqueous solution red.^ 

1 Cf. also A. F. Joseph, y. Soc. Chem. Ind., 191 1, 29, 11 89. 

'^ For reactions distinguishing gallic from tannic acid, cf. Z. anal. Chem., 1889, 28, 103, 351 ; 
1892, 31, 88 ; 1896, 35, 590; Fhartn, Zenlralh., 1899, p. 302 ; and Merck's Reag.-Veiz., 1908, 
p. 294. 

Ill z 



354 ORGANIC PREPARATIONS 



Tests for Impurities. 

Inorganic Matter. — No residue should be left on igniting i g. of 
gallic acid. 

Sulphuric Acid. — Barium chloride solution should give no precipi- 
tate when added to an aqueous solution of gallic acid (i : 50), acidified 
with I c.c. of hydrochloric acid, and allowed to stand for one hour 
at a temperature of 50 . 

Water. — On drying at 100 till constant, gallic acid should not lose 
more than 10 per cent, in weight. 

Solubility in Water. — i g. of gallic acid should dissolve completely 
in 20 c.c. of water, on warming ; the aqueous solution should be 
colourless, or at most only have a faint yellowish coloration. 

Quantitative Estimation. 

The following method given by W. P. Dreaper ^ may be used : — 
5 g. of the gallic acid to be examined are dissolved in i litre of water. 
To 100 c.c. of this solution i g. of barium carbonate made up into 
a thin paste with water is added (to combine with the free sulphuric 
acid produced in the reaction) ; the mixture is then heated to 90' and 
N\\ copper sulphate solution run in until copper can be detected in the 
solution by means of potassium ferrocyanide. This end-point is shown by 
a brown coloration being produced when a drop of the liquid is put 
on to filter paper and a drop of potassium ferrocyanide solution allowed 
to fall on to it. Having thus found how much copper sulphate solution 
is required for the gallic and tannic acids together in 100 c.c. of the 
above solution {i.e., for 0-5 g. of substance), the tannic acid is precipitated 
out of 200 c.c. of the same solution by adding 28-6 c.c. of a 2 per cent, 
solution of gelatin, saturating the mixture with common salt, adding 
5 g. of barium sulphate and 10 c.c. of dilute sulphuric acid (i : 20), and 
making up to 400 c.c. The mixture is well shaken, and the tannic 
acid filtered off. The content of gallic acid in 200 c.c. of the filtrate 
is determined by titrating with copper sulphate solution. The difference 
between the two titrations gives the amount of tannic acid contained 
in the gallic acid taken. 

The copper sulphate solution is best standardised against pure gallic 
acid and pure tannin. Gallic acid of sufficient purity for this purpose 
is obtainable, and tannic acid of like purity is prepared by shaking 
up pure tannin with ether until no reaction is obtained with potassium 
cyanide, and then drying till constant. By this method, gallic and 
tannic acids may be accurately estimated, either individually or together, 
but in determining both together the result for tannic acid comes out 

' J. Soc. Chem. I>id., 1893, 12, 412. 



GELATIN 355 

somewhat high, since the precipitation with gelatin solution carries 
down some gallic acid with the tannic acid. 

Gelatin. 

The best commercial gelatin forms colourless, or almost colourless, 
thin, transparent flakes of glassy lustre, which should be tasteless and 
odourless. 

Gelatin swells up in water, dissolving readily in hot water. The 
hot solution should be clear or only slightly opalescent. On cooling a 
solution of I g. of gelatin in lOO c.c. of water, it should solidify to a 
jelly. Gelatin is insoluble in alcohol and in ether. Tannic acid solution 
produces a flocculent precipitate when added to a dilute aqueous solution 
of gelatin.^ 

Tests for Impurities. 

Inorganic Matter. — Not more than o-2 g. of residue should remain 
on igniting lo g. of gelatin. The cold, ignited residue is tested for 
copper 2 by dissolving in 3 c.c. of hydrochloric acid and adding excess of 
ammonia, when no blue c'oloration should be produced. 

Free Acids. — According to J. Messner no commercial gelatins are 
free from acid.^ In the best commercial varieties he found up to i 
per cent, of free acid (calculated as sulphuric acid). Taking this figure 
as an allowable maximum, products may be tested as follows : — Red 
litmus paper should be turned blue after adding o-2 c.c. of iV/i potassium 
hydroxide to a warm solution of i g. of gelatin in 100 c.c. of water. 

Sulphurons Acid. — Good gelatin generally contains from o-oi-o-02 
per cent, of sulphur dioxide.'* The quantitative estimation is some- 
what lengthy, and the following test (given by the German Pharma- 
copoeia) suffices : — 5 g. of gelatin are allowed to soak in 30 c.c. of 
water in a wide-mouthed, 150 c.c. flask and then dissolved by gently 
warming on the water-bath. 5 g. of phosphoric acid (25 per cent.) are 
then added, the flask loosely closed by a cork, on the under side of which 
is fastened a moistened piece of potassium iodide and starch paper, and 
the contents heated on the water-bath, and frequently shaken round 
with care. No temporary or permanent blue coloration of the paper 
should take place within a quarter of an hour. 

A method for the quantitative estimation of free and combined 
sulphurous acid in gelatin has been recently described by R. W. Sindall 
and W. Bacon.^ 

Water. — The water in gelatin is determined by drying at 105°. A 

1 For identifying reactions for gelatin, cf. Liesegang, Pharm. Zeit., 1910, 55, 283. 

2 QC W. B. Hart,/. Soc. Chetn. Ind., 1909, 28, 739. ^ Merck's Jahresber., 1900, p. 3r. 
* Cf. W. Lange, Arb. Kais. gesundh. Ami, 1909, 32, 144 ; J. Soc. Chem. hid., 1909, 28, 995. 

5 Analyst, 1914, 39, 20. 



356 ORGANIC PREPARATIONS 

good sample should not contain more than 20 per cent, of water; the 
proportion in commercial gelatins usually varies from 11 to 14 percent.^ 

Guaiacol. 

OH(i) 
QH^( . Molec. \vt. 12406. 

^OCH3(2) 

Guaiacol is prepared cither as a clear, colourless, refractive, oily 
liquid boiling at 205'', or in the form of colourless crystals which melt at 
28^ It dissolves in about 60 parts of water, and is readih- soluble in 
alcohol and in ether. The addition of one drop of a dilute solution of 
ferric chloride to the aqueous solution produces a blue coloration which 
immediately changes to reddish-brown, and when added to an alcoholic 
solution, a coloration changing from green through blue to greenish- 
brown is produced."- 

Tests for Impurities. 

A mixture of l vol. of guaiacol with 2 vols, of sodium h)'droxide 
solution should be clear and should remain clear and colourless on 
diluting with 10 vols, of water. A mixture of guaiacol with 2 vols, of 
potassium hydro.xide solution should solidify to a white crystalline mass 
in a short time. Guaiacol should dissolve to a colourless solution in 
cold, concentrated sulphuric acid. 

Guaiacol Carbonate. 
C0(0 . C„H, . OCH3).. Molec. wt. 274- 1 1 2. 

This is the most important pharmaceutical preparation obtained 
from guaiacol. It is a white, almost odourless, crystalline powder. It 
dissolves readily in chloroform and in hot alcohol, sparingly- in cold 
alcohol and in ether, and is insoluble in water. It melts between 86° 
and 88'. Guaiacol carbonate contains approximately 90 per cent, of 
guaiacol. The latter is separated by saponifying 0-5 g. of guaiacol 
carbonate with a mixture of 10 c.c. of alcohol and potassium hydroxide 
solution. After evaporating off the alcohol, the residue is taken up with 
water, acidified with dilute sulphuric acid, and the guaiacol extracted 
with ether. On evaporating off the ether an oily residue smelling of 
guaiacol is left, and which, when dissolved in alcohol, gives the character- 
istic green coloration with ferric chloride. 

If about 0-2 g. of guaiacol carbonate is boiled for from two to three 
minutes with 10 c.c. of quite clear alcoholic potash (i g. potassium 
hydroxide in 20 c.c. of absolute alcohol), a white crystalline precipitate 

' Sind;ill and Bacon, loc. cil, 

'^ For identifying reactions, cf. Merck's /\eag.-\'e>:., 1908, p. 295. 



HEXAMETHYLENETETRAMINE 357 

separates out, which, after washing with alcohol, evolves carbon dioxide 
when treated with h)'drochloric acid. 

Tests for Impurities. 

Free Guaiacol. — A solution of 0-5 g. of guaiacol carbonate in 10 c.c. 
of hot alcohol should not change litmus paper and should give no blue 
or green coloration with ferric chloride. 

Hydrochloric Acid. — On shaking i g. of guaiacol carbonate with 
ro c.c. of water and filtering, the filtrate should give no reaction on 
acidifying with nitric acid and adding silver nitrate solution. 

Organic Impurities. — o-i g. of guaiacol carbonate should dissolve to 
a colourless solution in i c.c. of sulphuric acid. 

Inorganic Impurities. — Not more than 0-5 mg. of residue should be 
left on igniting 05 g. of guaiacol carbonate. 

Hexamethylenetetramine. 

(CH.,)(.N^. Molec. wt. 140-14. 

Hexamethylenetetramine is a colourless, crystalline powder which 
volatilises on heating without melting. It dissolves in 1-5 parts of 
water and in 10 parts of alcohol (of about 85 per cent, by weight). 
The solutions react alkaline with litmus paper. On heating the aqueous 
solution (i :20) with dilute sulphuric acid, formaldehyde, recognisable 
by its smell, is given off On further warming, after the addition of 
excess of sodium hydroxide solution, ammonia is evolved. Silver 
nitrate solution produces a white precipitate with aqueous solutions of 
hexamethylenetetramine (i : 20), which is soluble in excess of the 
latter. A carmine-red coloration is produced on carefully heating a 
mixture of o-i g. of hexamethylenetetramine with o-i g. of salicylic 
acid and 5 c.c. of concentrated sulphuric acid. 

Tests for Impiirities. 

Heavy Metals and Sulphuric Acid. — No precipitate should be pro- 
duced on adding either sulphuretted hydrogen water or barium nitrate 
solution to an aqueous solution (i : 20). 

Hydrochloric Acid. — On adding 5 c.c. of nitric acid and silver nitrate 
solution to an aqueous solution (i : lOo), at most, only a faint opalescent 
turbidity should be produced. 

Ammonium Salts. Paraformaldehyde. — On heating an aqueous 
solution (i : 20) to boiling with Nessler's reagent, neither a coloration 
nor a turbidity should be produced. 

hiorgajiic Impurities. — Not more than 0-5 mg. of residue should 
remain on volatilising i g. of hexamethylenetetramine. 



358 ORGANIC PREPARATIONS 

Quantitative Estimation. 

I g, of the preparation is evaporated to dryness on the water-bath 
with 40 c.c. of iV/i sulphuric acid ; formaldehyde is formed whilst the 
acid combines with the nitrogen to form ammonium sulphate. The 
residue is taken up with water and further evaporated down until the 
formaldehyde is completely driven off. It is then dissolved in lOO c.c. 
of water, and the excess of sulphuric acid titrated back with Nji alkali, 
using litmus as indicator. The difference between the number of cubic 
centimetres of alkali used and the number of cubic centimetres of acid 
taken in the first instance gives the number of cubic centimetres of 
acid used up in the formation of ammonium sulphate in accordance with 
the equation : — 

(CH.,),N, + 6H,0 + 2H2SO, = 6CH204-2(NHJ,SO,. 

I g. of hexamethylenetetramine corresponds, therefore, to 2874 c.c. 
of N/i sulphuric acid.^ 

Hydroquinone (Quinol). 

OH(i) 
CgH/ . Molcc. wt. 11005. 

^0H(4) 

Hydroquinone forms colourless and odourless six-sided prisms 
which melt at 169°, and at a higher temperature sublime undecomposed. 
The sublimed hydroquinone forms monoclinic leaf)' crystals. It 
dissolves in 17 parts of water at 15°, more readily in hot water, in 
alcohol, and in ether. It is but sparingly soluble in cold benzene. 

An aqueous solution reduces silver nitrate solution even at ordinary 
temperatures, and Fehling's solution only on warming. A small 
quantity of ferric chloride produces a temporary blue coloration which 
disappears on adding more ferric chloride, when small, green, shin)', 
crystalline leaves (quinhydrone) separate out. In contradistinction to 
catechol and resorcinol, an aqueous solution of h)droquinone is not 
precipitated by either lead acetate or by the basic acetate. 

Tests for Impurities. 

lnor{!;anic Matter. — Not more than 05 mg. of residue should remain 
on heating i g. of hydroquinone. 

Quinone. — The crystals of hydroquinone should be quite colourless. 

Phenol. — Ferric chloride should not produce a permanent violet 
coloration in an aqueous solution, and the aqueous solution should give 
no smell of phenol on boiling. 

Sulphuric Acid. — Barium chloride solution should produce no 
precipitate with a cold, saturated, aqueous solution of hydroquinone. 

' Base, Pharm. Zeil., 1907, 52, 851. 



IODOFORM 359 

Iodoform. 

CHI3. Molec. wt. 39377. 

Iodoform forms small hexagonal plates or leafy crystals of a lemon- 
yellow colour, with a smell somewhat resembling that of saffron. It 
melts at about 120°, and decomposes with separation of iodine at a 
higher temperature. It is soluble in 10 parts of ether, in 25 parts of 
absolute alcohol, in about 70 parts of 90 per cent, alcohol, and in 
75 parts of glacial acetic acid ; it dissolves also in benzene, chloro- 
form, petroleum spirit, and in carbon bisulphide. It is practically 
insoluble in water,^ 

Tests for Impurities. 

Inorganic Matter. — Not more than 0-5 mg. of residue should be left 
on igniting i g. of iodoform. 

Alkali Iodides and Chlorides. — On shaking up i g. of iodoform with 
10 c.c. of water and filtering, the filtrate should give only an immediate 
opalescence with silver nitrate solution. 

Alkali Carbonates and Sulphates. — Barium chloride solution should 
produce no precipitate when added to an aqueous filtrate prepared as 
above. 

Water. — Iodoform should dissolve to a clear solution in ten times 
the quantity of petroleum spirit. It should, at most, not lose more than 
I per cent, in weight when dried over sulphuric acid for twenty-four 
hours. 

Quantitative Estimation. 

About I g. of powdered iodoform is heated in a glass flask in a 
boiling water-bath, and frequently shaken during one hour with 100 c.c. 
of iV/io silver nitrate solution. Any yellow precipitate adhering to the 
sides of the flask is then washed down into the solution with as little 
water as possible, and the whole kept gently boiling over a wire gauze, 
using a small Bunsen burner, for half an hour. (This operation may 
also be carried out with alcoholic solutions of iodoform and silver 
nitrate.) On cooling, the solution is filtered into a 250 c.c. measuring 
flask, and the precipitate and filter paper afterwards washed with water 
until the flask is full up to the mark. The excess of silver nitrate is 
determined in 50 c.c. of the filtrate by titrating either with A710 sodium 
chloride solution, or with iV/io ammonium thiocyanate solution. The 
number of cubic centimetres of sodium chloride solution or of ammonium 
thiocyanate solution used, multiplied by 5 and subtracted from 100, 
gives the number of cubic centimetres of silver nitrate solution decom- 

^ For identifying reactions, cf. Merck's Rea^.-Verz., 1908, p. 296. 



360 ORGANIC PREPARATIONS 

posed by the quantity of iodoform taken. This figure, multiplied by 
001312, gives the amount of iodoform in the original weighing taken, 
and the percentage content is thus readily calculated. A good sample 
should show a percentage of at least 99-5 of iodoform when analysed by 
this method. 

The method may be simplified by decomposing the iodoform with 
silver nitrate directly in a 250 c.c. measuring flask, and after cool- 
ing making up with water to the mark. When the precipitate has 
settled, 50 c.c. of the clear solution are withdrawn and titrated as 
above. 

The following method of estimation is also to be recommended : — 
I g. of iodoform is dissolved in 100 c.c. of a mixture of i part of 
ether and 3 parts of alcohol, 10 c.c. of this solution transferred to a 
beaker, a few drops of fuming nitric acid added, followed immediately 
by 10 c.c. oi N/10 silver nitrate solution, and the mixture then carefully 
heated on the water-bath until the smell of ether and of nitrous acid 
has disappeared. When cold, 100 c.c. of water and about i c.c. of iron 
alum solution are added, and the excess of silver nitrate titrated with 
Nlio ammonium thiocyanate solution. Not more than 2-5 c.c. of the 
latter should be required.^ In carrying out this method of estimation 
care must be taken to add the silver nitrate solution before the nitrous 
acid has converted the iodine into iodic acid, which would render the 
analysis inaccurate.- 

Lactic Acid. 
CH3.CHOH.COOH. Molcc. wt. 9005. 

Fermentation lactic acid is a clear, colourless or slightly yellow, 
odourless, syrupy liquid, miscible in all proportions with water, alcohol, 
and ether. It is insoluble in benzene, chloroform, and carbon 
bisulphide. The official lactic acid of the British Pharmacopoiia 
has a sp. gr. of i-2i and contains 75 per cent, of pure lactic acid. 
Chemically pure lactic acid is an extremely hygroscopic crystal- 
line mass, which melts at 18° and boils at Ii9°-I20" under 12 mm. 
pressure. The 90 per cent, commercial product is the most important 
technically. 

The characteristic formation of crystalline zinc and calcium salts 
is too long and tedious a test for general purposes. The following 
test is therefore applied: — 3 c.c. of the acid are warmed with 10 c.c. 
of potassium permanganate .solution (i : 1000), when the characteristic 
smell of aldehyde is given off.^ 

* Utz, A/>ol/t. Zeit., 1906, p. 930. ^ Z. angnv. Chem.^ 1909, 22, 1059, 1090. 

3 Cf. Merck's Reag,-Verz., 1908, p. 297. 



LACTIC ACID 361 

Tests for Impurities. 

Inorganic Matter. — On strongly heating, lactic acid chars and finally 
burns away, leaving a small residue which in no case should exceed 
o-i per cent. 

Copper, Lead, Zinc, Iron. — Sulphuretted hydrogen water should 
give no reaction with a lo per cent, aqueous solution of lactic acid. 

Calcium. — An aqueous solution (i : lo) should give no precipitate 
with excess of ammonia and ammonium oxalate solution. 

Sulphuric Acid and Chlorine Compounds. — Neither barium chloride 
solution nor silver nitrate solution should produce a precipitate with 
a I : lo solution of the acid. 

Butyric and Acetic Acids. — No smell of fatty acids should be evolved 
on gently warming lactic acid. 

Tartaric and Oxalic Acids. — No turbidity should be produced on 
mixing 5 c.c. of lactic acid with 100 c.c. of lime water. 

Citric Acid. — The mixture with lime water should also not become 
turbid on warming. 

Sugar. — On carefully pouring 5 c.c. of lactic acid over 5 c.c. of 
sulphuric acid in a test tube, the sulphuric acid should not assume a 
brown coloration within half an hour. The temperature of the reaction 
should not be allowed to rise above i^"", otherwise lactic acid, free from 
sugar, will react and produce a darkening of the sulphuric acid. Sugar 
may also be tested for by means of Fehling's solution, but unless care 
be taken, the separation of a very small quantity of cuprous oxide 
may be overlooked. 

Glycerol — 5 g. of lactic acid are warmed with an excess of zinc 
carbonate, and the mixture dried at 100°. On extracting the residue 
with absolute alcohol and evaporating off the alcohol on the water- 
bath, no sweet-tasting residue should remain, 

Mannite, Grape Sugar, Cane Sugar, Glycerol. — On dropping i c.c. 
of lactic acid into 2 c.c. of ether, no temporary or permanent turbidity 
should be produced.^ 

Sarco-Lactic Acid. — A lO per cent, aqueous solution of lactic acid 
should give no turbidity on the addition of copper sulphate solution. 

Malic and Glycollic Acids. — No turbidity should be produced on 
adding basic lead acetate to a 10 per cent, solution of lactic acid. 
(The absence of sulphuric acid being taken for granted.) 

Quantitative Estimation. 

For the quantitative estimation, 10 g. of lactic acid are dissolved 
in 1000 c.c. of water. 100 c.c. of this solution are warmed in a flask, 
in a boiling water-bath, for ten minutes with 15 c.c. ofTV^r potassium 

1 Cf. Pharm. Zentralh., 1892, p. 676. 



362 ORGANIC PREPARATIONS 

hydroxide, and then titrated with Nji hydrochloric acid, using phenol- 
phthalein as indicator, i c.c. of Nji potassium hydroxide solution 
corresponds to 009048 g. of lactic acid. The warming with potassium 
hydroxide is necessary in order to convert any acid present as 
anhydride into the acid (in the 75 per cent, acid a quantity of anhy- 
dride is present, corresponding to about 15 per cent, of acid), otherwise 
the titration would lead to an erroneous result. For this reason it is 
not advisable to directly titrate a freshly made-up solution of lactic 
acid with potassium hydroxide solution. 

F. Ulzer and H. SeideP give the following method: — 10 g. of 
lactic acid are dissolved in water and made up to i litre. 100 c.c. of 
this solution are taken, and a concentrated solution of potassium 
hydroxide added until the solution contains 3 g. of potassium hydroxide, 
when a 5 per cent, potassium permanganate solution is added, with 
shaking, until the colour of the solution changes from green to violet. 
The solution is then heated to boiling, which should not discharge 
the violet coloration, and, after cooling, hydrogen peroxide is added 
until the coloration is discharged. The solution is then again boiled, 
filtered, the filter paper washed, and the oxalic acid produced in the 
reaction precipitated as calcium oxalate after acidifying with acetic 
acid. The calcium oxalate is ignited and weighed as calcium oxide. 
From the weight of calcium oxide, the corresponding quantity of oxalic 
acid and of lactic acid may be calculated. 

Methyl Alcohol (Wood Spirit). 

CH3.OII. Molec. wt. 32-03. 

Methyl alcohol is a clear, colourless liquid, possessing a characteristic 
smell. It has a sp. gr. of 0798, boils at 65°-66°, and is miscible in all 
proportions with water, alcohol, ether, and with fatty and essential oils. 

Tests for Impurities. 

Non-volatile Matter. — No appreciable residue should remain on 
evaporating 30 c.c. of methyl alcohol on the water-bath. 

Acetone and Ethyl Alcohol. — On shaking together 50 c.c. of 2N 
sodium hydroxide solution and 5 c.c. of methyl alcohol in a cylinder, 
then adding 25 c.c. of 2N iodine solution, and again shaking, there 
should be no separation or smell of iodoform. G. Deniges- has 
published a method for detecting traces of acetone, using mercuric 
sulphate, by means of which he claims that 0003 per cent, of acetone 
can be detected. 

Evipyreuviatic Matter. — i c.c. of methyl alcohol should dissolve in 

1 Monatsh., 1897, 18, 138 ; /. Chfm. Soc. Ahstr., 1897, 72, 389. 
'^ Merck's Reag.-l'erz., 1 908, p. 56. 



METHYL ALCOHOL 363 

lo c.c. of water without turbidity. No coloration or only a faint yellow 
coloration should be produced on adding 5 c.c. of concentrated sulphuric 
acid gradually to 5 c.c. of methyl alcohol, the mixture being cooled 
during the addition. 

CiUoroforni. — No smell of isonitrile should be evolved on heating to 
boiling 10 c.c. of methyl alcohol with a mixture of 3 drops of aniline 
and 10 c.c. of alcoholic potash (10 per cent.). 

Aldehyde. — On shaking 10 c.c. of methyl alcohol with 10 c.c. of 
sodium hydroxide solution (i : 3), the mixture should remain colourless. 

Substances oxidised by Permanganate. — The pink coloration pro- 
duced by the addition of a drop of yV/io potassium permanganate 
solution to 10 c.c. of methyl alcohol should not completely fade away 
within ten minutes. 

In addition to chemically pure methyl alcohol, other qualities come 
on to the market which only partially satisfy the requirements given 
above. The examination of wood naphtha is described in the section 
on "Alcohol, Potable Spirits, and Liqueurs," p. 715. 

Quantitative Estimation. 

The estimation of methyl alcohol in mixtures of the alcohol and 
water is effected by means of the specific gravity. A Table of the 
specific gravities of such mixtures, giving the percentages of methyl 
alcohol by weight, is included in the section on " Organic Dyes," Vol. 
II., Part II., p. 894. 

In other cases methyl alcohol is generally estimated by determining 
the amount of methyl iodide produced from a known quantity of the 
alcohol, a method due originally to Krell, which has been worked out by 
M. Grodzky and G. Kramer.^ For this purpose 30 g. of amorphous 
phosphorus are placed in a small 60 c.c. flask fitted with an upright 
condenser, and after allowing 10 c.c. of methyl alcohol to drop in from 
a small separating funnel, 10 c.c. of a solution of i part of iodine in i 
part of hydriodic acid (sp. gr. 1-7) are added. After the solution has 
digested for a short time, the contents of the flask are allowed to cool, 
the flask connected up with an ordinary condenser, and the contents 
distilled off on the water-bath, the distillate being collected in a 
graduated glass cylinder containing some water. When the distillation 
is ended, the condenser is washed out with water, the distillate 
well shaken, and the number of cubic centimetres of separated methyl 
iodide read off at 15". 

The form of this method, as used for the estimation of methyl 
alcohol in wood naphtha, is described on p. 716, 

Quantitative Estimation in presence of Ethyl Alcohol. — For the 

' Ber., 1874, 7, 1492. 



364 ORGANIC PREPARATIONS 

estimation of methyl alcohol, in presence of ethyl alcohol, the method of 
T. E. Thorpe and J. Holmes,^ which depends upon the oxidation of the 
methyl alcohol to carbon dioxide, is reliable and accurate. The 
process is described in detail in the section on " Alcohol, Potable 
Spirits, and Liqueurs," p. 717. 

Estiuiation of Acetone. — G. Kramer's method for estimating acetone 
in methyl alcohol has been described above as a method for the 
quantitative estimation of acetone (p. 309). 

For the estimation of acetone in methyl alcohol, i c.c. of the sample 
is shaken in a stoppered measuring cylinder with 10 c.c. of 2N 
sodium hydroxide solution, and 5 c.c. of 2N iodine solution added. 
After standing for some time, 10 c.c. of ether are added, the mixture 
again shaken, the volume of the separated ether layer read off, and an 
aliquot part, about 5 c.c, withdrawn, allowed to evaporate on a clock- 
glass, and the residual iodoform dried over sulphuric acid and weighed. 
3-94 g. iodoform correspond to 0-58 g. of acetone. 

The following volumetric modification of this method is due to 
J. Messinger^: — 20 c.c. of potassium hydroxide solution (56 g. to the 
litre) and i c.c. of methyl alcohol arc shaken up together in a 250 c.c, 
stoppered flask, and 20-30 c.c. of A7s iodine solution run in from a 
burette. The contents of the flask are shaken for about half a minute 
until the liquid clears, when 20 c.c. of hydrochloric acid (sp. gr. 1-025) 
and A710 sodium thiosulphate solution, in excess, are added. The 
solution is then titrated back with A75 iodine solution, using starch 
solution as indicator. 

I mol. of acetone (58-048 g.) requires 3 mols. of iodine (761-52 g.) 
for the formation of iodoform, in accordance with the equations : — 

2CH.j.CO.CH., + 6I, + 6KOII = 2CH3. CO . Cl3+6KI+6H._,0. 
2CH3.CO.CI3+2KOH = 2CHl3+2KC2H,0.,. 

761-52:58-048 = I:A 
1 = quantity of iodine, A = quantity of acetone 

Hence, A = i . 5|:24^ _ 007623 1. 
761-52 

The quantity of acetone (in grams) in 100 c.c. of methyl alcohol is 
therefore found by multiplying the quantity of iodine used up by 
7-623. The percentage content by weight is calculated from the 
specific gravity of the methyl alcohol. 

The following method for the estimation of acetone in methyl 
alcohol, due to S. J. M. Auld,^ is based on the formation of bromoform 
and its subsequent saponification by alcoholic potassium hj-dro.xide. 
The sample is diluted with water, so that the solution to be tested 

' /. Chem. Soc, 1904, 85, l. - />V/., 1888, 21, 3366, 

•' y. Soc. Chem. I ml., 1906, 25, 1 00. 



METHYL ALCOHOL. MORPHINE 365 

contains from o- 1-0-2 g. of acetone, and the latter placed in a flask 
fitted with an upright condenser and dropping funnel. After adding 
20-30 CO. of potassium hydroxide solution (10 per cent.), a solution of 
bromine (200 g. bromine and 250 g. potassium bromide to a litre of 
water) is added from the dropping funnel until the mixture has acquired 
a faint yellow tinge. The whole is then warmed on the water-bath, at 
about yo", the bromine solution being added, drop by drop, until a 
slight coloration remains permanent. The excess of bromine is 
removed by boiling for a short time with potassium hydroxide solution, 
and the bromoform then distilled off. The condenser is washed down 
with alcohol, and 50 c.c. of alcohol and sufficient potassium hydroxide 
added to produce a distillate containing about 10 per cent, of potassium 
hydroxide. The bromoform is then saponified by boiling for about 
three-quarters of an hour, using a reflux condenser, and, when cold, the 
contents of the flask are neutralised with nitric acid and made up to 
500 c.c. with water. The solution is then titrated in the usual way 
with Njio silver nitrate solution. 239-76 parts of bromine correspond 
to 58-048 parts of acetone. 

Morphine. 
C17H19O3N . H,0. Molec. wt. 303-18. 

Morphine crystallises in colourless needles or prisms which lose 
their water of crystallisation at i io°-i20", and melt at about 230". It 
is only very sparingly soluble in water (about i : 5000) and the aqueous 
solution is laevorotatory ; it dissolves in lOO parts of 90 per cent, alcohol, 
in 50 parts of absolute alcohol, in lOO parts of chloroform, and in 1200 
parts of ether. It is practically insoluble in benzene. 

It is examined in the same way as morphine hydrochloride. (Cf. 
infra.) 

The free base may be estimated volumetrically by treating with an 
excess of Njio hydrochloric acid, and after adding water, ether, and 
iodo-eosine as indicator, titrating back with Ayio potassium hydroxide. 
I c.c. of iV/io hydrochloric acid corresponds to 0-02852 g. of anhydrous 
morphine, or to 003032 g. of C^yH^gNOg. H.^O. 

Morphine Hydrochloride. 

Ci^H.gOaN . HCl . 3H,0. Molec. wt. 375-68. 

Morphine hydrochloride crystallises in white, silky, non-efflorescent 
needles, which generally come on to the market compressed into cubes. 
It is soluble in 25 parts of water and in 50 parts of 90 per cent, 
alcohol. From the cold, saturated solution the salt is partially thrown 



366 ORGANIC PREPARATIONS 

down on the addition of concentrated hydrochloric acid. A deep red 
coloration is produced on heating a few small crystals for a quarter of 
an hour in a water-bath with 5 drops of sulphuric acid, allowing to 
cool, and then adding i drop of nitric acid. A mixture of o-i g. of 
morphine hydrochloride and 0-4 g. of cane sugar, added to sulphuric 
acid, colours the latter red ; the coloration is intensified by adding 
bromine water. On moistening with nitric acid, morphine h)dro- 
chloride becomes coloured red. A solution of morphine h)-drochloride 
in sulphuric acid turns brown on the addition of basic bismuth nitrate. 

Tests for Impurities. 

Inorganic Impurities. — On heating, 03 g. of morphine hydrochloride 
should burn away, leaving not more than 05 mg. of residue. 

On igniting morphine, there always remains a visible, not insigni- 
ficant residue, and it is only by weighing that it is possible to ascertain 
with certainty whether it is negligible. 

Free Hydrochloric Acid. — The aqueous solution should react neutral 
with litmus paper. 

Sugar and Organic Impurities. — Morphine hydrochloride should 
dissolve in sulphuric acid, producing a colourless or, at most, a faint 
pink-coloured solution. 

Foreign Alkaloids. — On adding a drop of potassium carbonate 
solution (1:3) to 5 c.c. of an aqueous solution of morphine hydro- 
chloride (i : 30), a pure white, crystalline separation takes place " 
immediately or in the course of a iow seconds, which should remain 
colourless in contact with air, and on shaking up with chloro- 
form the latter should not be reddened (apomorphine). Instead 
of potassium carbonate, potassium bichromate may also be used, 
which brings about an immediate oxidation. On shaking with 
chloroform, the latter is immediately turned red if apomorphine 
be present. The addition of a drop of ammonia to 5 c.c. of an 
aqueous solution (i : 30) produces an immediate white, crystal- 
line precipitate, which should dissolve readily in sodium hydroxide 
solution, and slowly in ammonia or lime water, giving colourless 
solutions. On shaking up the sodium hydroxide solution with 
ether, the clear ethereal extract should yield no appreciable residue 
on evaporation. (A residue points to the probable presence of 
narcotine.) 

Water. — On drying i g. of morphine hydrochloride at lOO' till 
constant, at least 0856 g. of residue should remain. 

The methods for the examination of the two most important 
derivatives of morphine, viz., codeine and dionine, are appended. 



CODEINE. DIONINE 367 

Codeine (Methyl Morphine). 
Ci7Hj70N(OH)(OCH3) + H.30. Molec. wt. 317-19. 

Codeine forms colourless crystals which are soluble in 80 parts of 
cold, and in 17 parts of boiling water. It is readily soluble in alcohol, 
ether, and chloroform. On drying at 100^, it loses 5-68 per cent, in 
weight. Anhydrous codeine melts at 153°. The free codeine base 
may be estimated volumetrically in the same way as morphine 
(P- 365). I c.c. of Njio hydrochloric acid corresponds to 0-03172 g. of 
codeine +H2O. 

The salt of codeine which finds the widest application is the 
phosphate, Ci^Hi^ONCOHXOCHg). H3PO, + 2H20. Molec. wt. 433-234. 
It crystallises in fine white needles, soluble in 3-5 parts of water, and 
less soluble in alcohol. Its aqueous solution reddens litmus paper. 
Codeine phosphate dissolves in sulphuric acid to a colourless solution, 
sometimes exhibiting a transitory pale red coloration ; on adding a 
drop of ferric chloride, the mixture turns blue on warming ; when cold, 
a drop of nitric acid changes the blue coloration to a deep red 

Tests for Impurities. 

Sulphuric and Hydrochloric Acids. — An aqueous solution (1:20), 
acidified with nitric acid, should show no change with silver nitrate 
solution, and barium nitrate solution should produce no immediate 
turbidity. 

Morphine. — A solution of a small piece of potassium ferricyanide in 
10 c.c. of water, to which is added a drop of ferric chloride, should not 
be turned blue immediately on the addition of i c.c. of an aqueous 
solution of codeine phosphate (i : 100). 

Water. — Codeine phosphate should not lose more than 8-5 per cent, 
in weight on drying at 100". 

Quantitative Estimation. 

This may be carried out by dissolving a weighed quantity of the 
salt in water, making alkaline with sodium carbonate solution, 
extracting with ether, and titrating the ethereal codeine solution 
obtained with A^/io hydrochloric acid, using iodo-eosine as indicator. 

Dionine (Ethyl Morphine Hydrochloride). 

Ci7Hi80.3N(OC.,H5)HCl + 2H,0. Molec. wt. 385-69. 

Dionine is a white, crystalline powder consisting of fine small 
needles soluble in 12 parts of water and in 25 parts of alcohol (of 
about 85 per cent, by weight). The solution in water reacts neutral 



368 ORGANIC PREPARATIONS 

with litmus paper. On adding a solution of iodine in potassium iodide 
to the aqueous solution (i : lOO), a light brown precipitate is thrown 
down, ooi g. of dionine dissolves in lo c.c. of sulphuric acid (sp. gr. 
1-84) with evolution of hj'drochloric acid, a clear, colourless solution 
resulting which, when warmed with a drop of ferric chloride solution, 
first turns green, then deep blue, and on the further addition of 
2-3 drops of nitric acid, the colour changes to deep red. 

Tests for Impurities. 

Codeine. — i or 2 drops of ammonia (10 per cent. NH3) added to a 
solution of 01 g. of dionine in i c.c. of water, produces a white pre- 
cipitate which is not dissolved on the further addition of 10-15 drops 
of ammonia. (Under similar conditions codeine goes readilv into 
solution.) 

Morpliine. — A solution of a small crystal of potassium ferricyanide 
in 10 c.c. of water, to which a drop of ferric chloride solution is added, 
should not turn immediately blue, but should only very slowly develop 
a bluish -green coloration on the addition of i c.c. of an aqueous 
solution of dionine (i : 100). (Morphine gives an immediate deep blue 
coloration.) 

Inorganic Impurities. — Not more than 05 mg. of residue should 
remain on igniting i g. of dionine. 

Water. — On drying at 100 , dionine should not lose more than 
9-5 per cent, in weight. 

Quantitative Estimation. 

The dionine (0-25 g.) is dissolved in 50 c.c. of absolute alcohol 
in a glass-stoppered flask, and the solution titrated with iV/io potassium 
hydroxide, using Poirrier's blue as indicator {cf. Quinine, p. 381). i c.c. 
oi N/io potassium hydroxide corresponds to 00386 g. of dionine. 

a-Naphthol. 

Ci(,H. .OH. Molec. wt. 14406. 

u-Naphthol crystallises in colourless needles possessing a phenol- 
like smell. It melts at 97" and boils at 280". It is sparingly soluble 
in water, but readily in alcohol, ether, benzene, and chloroform. 

Qualitative Tests. 

I. An aqueous .solution of a-naphthol gives a violet coloration with 
calcium hypochlorite .solution, and also with a solution of iodine in 
potassium iodide on the addition of an excess of sodium hydroxide 
solution. 



NAPHTHOL 369 

2. Ammonia produces a blue fluorescence when added to an aqueous 
solution. 

3. An alcoholic solution (1:5) gives a violet coloration with ferric 
chloride ; the coloration disappears on standing for some time. 

4. On melting 0-5 g. of a-naphthol with 12 g. of chloral hydrate for 
ten minutes in a boiling water-bath, the mass turns red, and dissolves in 
alcohol, producing a red coloration. 

5. If o-l g. of vanillin be dissolved in 2 c.c. of sulphuric acid, and 
then o-i g. of a-naphthol added, a very stable red coloration is produced 
after shaking for some time.^ 

Tests for Impurities. 

Inorganic Acids. — On shaking i g. of a-naphthol with lOO c.c. of 
water, the filtrate should not redden blue litmus paper. 

Organic Impurities insoluble in Sodium Hydroxide. — i g. of a-naphthol 
should dissolve completely to a clear solution in 5 c.c. of sodium hydroxide 
solution of sp. gr. i- 168- 1-172 and 5 c.c. of water. 

Inorganic Matter. — No appreciable residue should remain on ignit- 
ing I g. of a-naphthol. 

Quantitative Estimation. 

The acidimetric method for the estimation of a-naphthol is described 
in the section on " Organic Dyes," Vol. II., Part II., p. 882. 

^-Naphthol. 

C10H7 . OH. Molec. wt. 144-06. 

/3-Naphthol forms colourless, glistening, odourless, rhombic crystals, 
which melt at 128°, and boil at 285°-290° with slight decomposition. 

Qualitative Tests. 

1. Calcium hypochlorite solution gives a yellow coloration with an 
aqueous solution of /3-naphthol ; the coloration disappears if a slight 
excess of the reagent be added. /3-Naphthol gives no coloration with a 
solution of iodine in potassium iodide containing excess of sodium 
hydroxide. 

2. Ammonia produces a violet fluorescence when added to an 
aqueous solution. 

3. An alcoholic solution (i : 5) gives a stable green coloration with 
ferric chloride. 

4. On melting 0-5 g. of /5-naphthol with 12 g. of chloral hydrate for 
ten minutes in a boiling water-bath, the mass turns a deep blue, and 
dissolves in alcohol, producing a blue coloration. 

^ For other colour reactions, cf. Merck's Reag.-Verz., 1908, p. 297. 
Ill 2 A 



370 ORGANIC PREPARATIONS 

5. If 01 g. of vanillin be dissolved in 2 c.c. of sulphuric acid, and 
then o-i g. of /3-naphthol added, the solution turns a chlorophyll-green 
colour. 

Tests for Impurities. 

a-Naphthol. — If i g. of /5-naphthol be dissolved in 100 c.c. of boiling 
water, and the solution cooled and filtered, the filtrate should not show 
a violet coloration on the addition of excess of calcium hypochlorite 
solution. Other methods for the detection of a-naphthol, and for the 
differentiation of the two isomers, are described in the section on 
"Organic Dyes," Vol. II., Part II., pp. 881 et scq. 

Naphthalene. — i g. of /3-naphthol should dissolve completely, leaving 
no residue, in 50 c.c. of ammonium hydroxide (sp. gr. 0-96). 

Organic Impurities. — The above ammoniacal solution should not 
have a brownish colour, but should only be pale yellow. 

Organic Acids. — On shaking i g. of ^^-naphthol with 100 c.c. of 
water and filtering, the filtrate should not redden blue litmus paper. 

Quantitative Estimation. 

F. W. Kiister's method for the acidimetric estimation of ;8-naphthol 
by means of its picric acid compound, is described in the section on 
" Organic Dyes," Vol. II., Part 1 1., p. 882. 



Oxalic Acid. 

C.3H.O,. 2H,0. Molec. wt. 126-05. 

Oxalic acid crystallises in colourless, monoclinic crystals, which should 
show no signs of efflorescence. It dissolves in 10 parts of water at 15°, 
in about 3 parts of boiling water, in 2-5 parts of alcohol at 15 , in i-8 
parts of boiling alcohol, and in about 100 parts of ether. The hydratcd 
acid heated in a capillary tube melts in its water of crystallisation at 
98'; the anhydrous acid melts at 187°. On heating oxalic acid with 
sulphuric acid, carbon monoxide and carbon dioxide are evolved. 
Calcium chloride, added to an aqueous solution containing excess of 
ammonia, produces a white precipitate, insoluble in acetic, but soluble 
in hydrochloric acid. 

Tests for Impurities. 

Inorganic Matter. — No appreciable residue should remain on igniting 
3 g. of oxalic acid. 

Amvioniiim Compounds. — On treating 2-5 g. of oxalic acid with 5 g. 
of potassium hydroxide dissolved in 30 c.c. of water, and then adding 



OXALIC ACID. PARALDEHYDE 371 

15 drops of Nessler's reagent to the solution, only a pale yellowish 
coloration, and not a reddish-brown coloration should result. 

Heavy Metals. — An aqueous solution (i : 10) should be perfectly 
clear. 30 c.c. of this solution should show no reaction on the addition 
of sulphuretted hydrogen water, or on the subsequent addition of 
ammonia, till alkaline. • 

Chlorides. — At most, only a faint opalescence should be produced 
on adding silver nitrate solution to a solution of 5 g. of oxalic acid in 
50 c.c. of water acidified with 15 c.c. of nitric acid. 

Sulphuric Acid. — No turbidity or precipitate should be produced on 
warming an aqueous solution (5 : 100), acidified with hydrochloric acid, 
with barium chloride solution within fifteen hours. 

Nitric Acid. — On carefully pouring a 10 per cent, solution of oxalic 
acid on to 10 c.c. of a solution of diphenylamine in sulphuric acid, no 
blue ring should be visible at the junction of the two layers of liquid. 

Quantitative Estimation. 

I g. of oxalic acid is dissolved in water and made up to 100 c.c, 
25 c.c. of which are titrated hot with TV/S potassium hydroxide solution, 
using phenolphthalein as indicator, i c.c. of A'/s potassium hydroxide 
corresponds to 0-012605 g. of crystallised oxalic acid. 

As an alternative method 25 c.c. of the above aqueous solution 
(i : 100) are titrated with A710 potassium permanganate solution after 
adding 6-8 c.c. of concentrated sulphuric acid, and warming to about 60°. 
I c.c. of iV/io potassium permanganate = 0-0063025 g, of crystallised 
oxalic acid. 

A Table of the specific gravity of aqueous solutions of oxalic acid is 
given in the section on "Organic Dyes," Vol. II., Part II., p. 898. 

Paraldehyde. 

(CH3COH)3. Molcc. wt. 132.10. 

Paraldehyde is a clear, colourless liquid with a peculiar, not irritating 
smell. It has a sp. gr. of 0-997-1-000, boils at 123°- 12 5° solidifies 
below 10^, and melts at io°-5. According to W. Squire,^ absolutely 
pure paraldehyde melts at 11^-7. Paraldehyde is readily soluble in 
alcohol, ether, benzene, chloroform, and petroleum spirit; it dissolves 
in 10 parts of water. A cold, saturated solution becomes turbid 
on warming. 

Tests for Impurities. 

Inorganic Matter. — 20 c.c. of paraldehyde should volatilise completely 
on hearing, leaving no residue. 

' Chem. and Drug.^ 1890, 37, 852. 



372 ORGANIC PREPARATIONS 

Hydrochloric aud SuIpJiuric Acids. — Neither silver nitrate nor barium 
nitrate solution should produce any precipitate in an aqueous solution 
(i : lo) acidified with nitric acid. 

Acetic and Valeric Acids. — lo c.c. of paraldehyde are dissolved in 
50 c.c. of alcohol, and phenolphthalein added ; not more than 0-5 c.c. 
of 7V/i potassium hydroxide should be required to produce the pink 
coloration. 

Alcohol. — The presence of alcohol is indicated by a too low specific 
gravity, melting point, and boiling point. On shaking up 20 c.c. of 
paraldeh}-de with 20 c.c. of a saturated solution of calcium chloride, the 
volume of the latter should show no increase. 

Water. — Paraldehyde should dissolve to a perfectly clear solution in 
an equal volume of official paraffin oil (liquid paraffin). 

Aldehyde. — On shaking up 10 c.c. of paraldehyde with 10 c.c. of 5 
per cent, potassium hydroxide solution, the latter should show no yellow 
or brown coloration within half an hour. 

Valeraldehydc. — No disagreeable smelling residue should remain on 
evaporating 10 c.c. of paraldeh)'de down on the water-bath. 

Amy I Alcohol. — The aqueous solution (i : 10) should be perfectly 
clear and contain no oily drops. 

Phenacetine. 

oaH,(i) 

CgH/ . Molec. wt. 179-11. 

^NH . COCH3(4) 

Phenacetine forms colourless, odourless, and tasteless, small, leafy 
crystals, which melt at 135°. It dissolves in 1400 parts of water at 15', 
in 70 parts of boiling water, and in 16 parts of alcohol. 

On boiling i g. of phenacetine with 10 c.c. of hydrochloric acid for 
about a minute, diluting with 100 c.c. of water, allowing to cool and 
filtering, the filtrate gradually assumes an intense red colour on adding 
1-2 c.c. of chromic acid solution (3 : 100).^ 

Tests for Imptirities. 

Inorganic Matter. — Not more than 0-5 mg. of residue should remain 
on igniting 0-5 g. of phenacetine. 

Orga7iic Impurities. — No brown coloration or carbonisation should 
be produced on dissolving 0-5 g. of phenacetine in 10 c.c. of sulphuric 
acid. 

Acctanilide. — On heating 0-5 g. of phenacetine with 8 c.c. of water to 
boiling, allowing to cool and filtering, the filtrate should show no 
reaction on boiling with potassium nitrite and dilute nitric acid, and 

' For identifying reactions for phenacetine, cf. Merck's Reag.-Verz., 1908, p. 298. 



PHENACETINE 373 

again boiling with nitric acid containing nitrous acid. According to 
J. Schroeder,^ 2 per cent, of acetanilide may be thus detected by the 
production of a red coloration. 

On boiling 0-3 g. of phenacetine for about one minute with 3 c.c. of 
25 per cent, hydrochloric acid, diluting with 30 c.c. of water and filtering, 
10 drops of 3 per cent, chromic acid solution should produce a stable 
ruby-red but not a green coloration.- 

Phenol. — If o-i g. of phenacetine be dissolved in 10 c.c. of hot water, 
the solution allowed to cool and then filtered, the filtrate should show 
no turbidity on adding excess of bromine water. 

Free Acids or Bases. — A 5 per cent, alcoholic solution of phenacetine 
should give no reaction with either red or blue litmus paper. 

Para-Phenetidene. — On stirring i g. of phenacetine into 5 g. of 
molten chloral hydrate, a clear and colourless melt should result. 
The mixture should not be heated in the steam - bath for longer 
than two to three minutes, otherwise pure phenacetine turns a rose- 
red colour. In the presence of^-phenetidene the melt becomes coloured 
violet.^ 

As an alternative test, 0-5 g. of phenacetine is dissolved by warming 
with 2 c.c. of alcohol, and 5 c.c. of iodine in potassium iodide solution 
(0-05 iodine : 1000) added. The solidified mass of separated phena- 
cetine is heated to boiling till dissolved. In the presence of traces 
of /-phenetidene the solution turns rose-red. The colour is more 
marked if the phenacetine be separated out a second time.* 

Ortho- and Diamino-Conipounds. — It is not usually necessary to test 
for these, since the commercial product is practically always free from 
such compounds as impurities.^ 

Para-CJdoracetanilide. — An adulteration with this substance is 
indicated by a low melting point. The chlorine may be detected by 
igniting the phenacetine with calcium carbonate in a similar manner to 
that by which benzoic acid is tested for chlorobenzoic acid^ (p. 321). 

Quantitative Estimation. 

A method for the quantitative estimation of phenacetine in mixtures 
has been worked out by J. L. Turner and C. E. Vanderkleed.'' 

1 Z.anal. C/iem., 1889, 28, 376. - Union pharmac.^ 1905, p. 484. 

3 Reuter, Phartn. Zeif., 36, 185 ; cf. also Pharm. Zentralh., 32, 313, 
■* Goldmann, Pharm. Zeit.^ 36, 208. 

* A method of testing for these compounds is given in Pharm. Zentralh., 31, 65, and 32, 313. 
^ Cf. Sudd, Apoih. Zeit.^ 1906, p. 236 ; C. Mannich, Ber. Pharm., 1906, p. 57 ; /. Soc. Chem. 
Ind., 1906, 25, 495. 

' Amer.J. Pharm., April 1907 ; J. Soc. Chem. Ind., 1907, 26, 486. 



374 ORGANIC PREPARATIONS 



Phenyldimethyl pyrazolone (Antipyrine). 

N(CH3).C— CH3 
C6H5.N/ II . Molec. vvt. I88-I2. 

\C0 CH 

Antipyrine crystallises in colourless plates possessing a slightly 
bitter taste. Melting point i io"'-i 12'. It dissolves in i part of water, 
I '5 parts of chloroform, and in 80 parts of ether. A solution of tannic 
acid added to an aqueous solution of antipyrine (i : 100) gives a 
voluminous white precipitate. 2 drops of fuming nitric acid added to 
2 c.c. of an aqueous solution produce a green coloration, and after 
boiling, the addition of a further drop of the acid causes a red coloration. 
A drop of ferric chloride solution added to 2 c.c. of an aqueous solution 
(i : 1000) produces a deep red coloration, which changes to a bright 
yellow on adding 10 drops of sulphuric acid.^ 

Tests for Impurities. 

The aqueous solution of antipyrine (i : i) should be clear and 
colourless. It should react neutral and remain unchanged on adding 
sulphuretted hydrogen water. A solution of i g. of the preparation in 
5 c.c. of water .should show no reaction on heating to boiling with 3 
drops of silver nitrate solution. No appreciable residue should remain 
on igniting o-i g. of antipyrine 

Quantitative Estimation.^ 

This may be carried out by means of iodine either volumetrically, 
the antipyrine being converted into the periodide of its hydriodide, 
CiiHioN.iO. HI. I.,, and the excess of iodine being titrated back with 
sodium thiosulphate, or gravimetrically by the method of the French 
Codex, in which the antipyrine is precipitated and weighed as the 
difficultly soluble iodo-antipyrine, which contains 70 per cent, of iodine.^ 

Phenylhydrazine. 
CcH., . NH . NH,. Molec. wt. 10808. 

Phenylhydrazine is a colourless or pale yellow, slightly refractive 
liquid, which boils at 243°, and on cooling solidifies in monoclinic plates 
which melt at 19". Phenylhydrazine forms a crystalline hydrate with 

' For other identifj'ing reactions, cf. Merck's Reag.-Verz,^ 1908, p. 290; also G. Lander and 
H. Winter, Analyst, 1 91 3, 38, 97. 

2 Cf. C. Kippenberger, Z. anal. Chem., 1896, 35, 675 ; /. Soc. Chem. Ind., 1896, 15, 266. J. 
Bougault,/. /'harm. Chim., 1900, II, 97 ; /. Soc. Chem. hid.., 1900, 19, 269. 

^ Cf. C. Astre,/. Pharm. C/iim,, 1912, 6, 2ll ; /. Soc, Chem. /«</., 1912, 31, 898. 



PHENYL HYDRAZINE 375 

water (2CgH5.N2H3. +H2O), which melts at 25°. It is but sparingly 
soluble in cold water, more so in hot, and very readily in alcohol and 
ether. It reduces Fehling's solution in the cold. If an aqueous or 
alcoholic solution of phenylhydrazine be heated for a short time 
with a few drops of an aqueous solution of trimethylamine, and 
then a few drops of a solution of sodium nitroprusside added, an 
intense cherry - red coloration is produced. On warming 5 c.c. of 
a solution of i g. of phenylhydrazine and 2 g. of sodium acetate 
in 15 c.c. of water and 1-5 g. of hydrochloric acid (sp. gr. M24) 
with 10 c.c. of grape sugar solution (i : 100) in a boiling water- 
bath, fine yellow needles of phenyl glucosazone begin to separate in 
about ten minutes ; an additional separation takes place on further 
heating. 

Tests for Impurities. 

A clear solution should result on dissolving 2 g. of phenylhydrazine 
in 20 c.c. of 5 per cent, acetic acid. 

Quantitative Estimation. 

A method for the quantitative estimation of phenylhydrazine has 
been worked out by H. Causse.^ It is based on the reduction of arsenic 
acid by means of phenylhydrazine to arsenious acid with formation of 
nitrogen and phenol, according to the following equation : — 

AsA+CfiHgNH.NHa = Ns + CeH^OH-f AsgOg+H.O. 

The estimation is carried out as follows : — 0-2 g. of phenylhydrazine 
and 60 C.C. of arsenic acid solution (125 g. of pure arsenic acid are dis- 
solved by heating on the water-bath in 450 c.c. of water and 1 50 c.c, of 
pure, concentrated hydrochloric acid ; when cold, the solution is filtered, 
and made up to 1000 c.c. with glacial acetic acid) are gently heated in 
a round-bottomed 500 c.c. flask, fitted with upright condenser, until the 
evolution of gas has subsided ; the contents of the flask are then boiled 
for about forty minutes. When cold, 200 c.c. of water are added, and 
the solution made faintly alkaline (until phenolphthalein just turns 
pink) with a solution of sodium hydroxide containing 200 g. of sodium 
hydroxide to the litre. The solution is then made just acid with 
hydrochloric acid, 60 c.c. of a cold, saturated solution of sodium 
bicarbonate added, and the arsenious acid finally titrated with A710 
iodine solution, i c.c. of the latter corresponds to 0-002702 g. of 
p?ienylhydrazine. 

1 Comptes rend.^ 1897, 125, 112 \ J. Soc, Chem. Ind., 1898, 17, 76. 



376 ORGANIC PREPARATIONS 

Phthalic Acid. 

COOH(i) 
CgH^/ . Molcc. wt. 166-05. 

\COOH(2) 

Phthalic acid crystalHses in small, colourless plates or prisms melting 
at 213'' and soluble in 200 parts of water, 10 parts of alcohol, and 145 
parts of ether; it is only very sparingly soluble in chloroform, and is 
insoluble in benzene and in pe