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XII.—On the Solid Fatty Acids of Coco-Nut Oi. By G. Carr Rosinson, 
FE.R.S.E., Demonstrator of Chemistry, Public Health Laboratory, Univer- 
sity of Edinburgh. (Plate XX.) . 
(Read 21st January 1878.) 
Most common oils and fats are mixtures of ethereal salts, termed glycerides 
or glyceric ethers, formed from glycerine and acids of the fatty, the oleic, and 
other allied series. 
Of the methods employed for the decomposition of oils and fats, the follow- 
ing are the most usual :— 
1. Distillation of the oil or fat; those which yield volatile acids, such as 
the acetins, butyrins, &c., may be more or less distilled without decomposition ; 
but those which yield fixed acids, eg., palmitin, olen, &c., are almost wholly 
decomposed by a heat of 300° C., yielding acrolein, numerous hydrocarbons, 
&e. 
2. Distillation with dilute sulphuric acid, by which the volatile acids are 
separated from the non-volatile. 
3. Distillation in a current of superheated steam, when the glycerides are 
decomposed, the fatty acids being liberated. 
4. Saponification ; oils and fats are decomposed by caustic alkalies into 
glycerine and a soap, the soap, when boiled with dilute sulphuric or hydro- 
chloric acid, being decomposed into a sulphate or chloride of the alkali 
employed and the fatty acid set free. 
To separate a mixture of fatty acids various methods are employed, of these 
- may be mentioned—the separation of the volatile from the jixed acids by dis- 
tillation ; fractional distillation of the volatile acids ; Liebig’s method of partial 
saturation ; whilst the jized acids are separated by dissolving in alcohol and 
fractional precipitation with acetate of lead. Another method is that usually 
adopted in the preparation of ethereal salts, and consists in saturating with 
gaseous hydrochloric acid the alcoholic solution of the mixed acids, separating 
the ethers so produced by fractional distillation, saponifying the pure ethers, 
decomposing the soap, and examining the fatty acid by analysis, melting point, 
&c., or by converting it into baryta, silver, or lead salt, and examining these. 
It was determined, at the suggestion of Dr Lerts and Dr Crum Brown, that 
an examination should be made in this manner of coco-nut oil. 
Coco-nut oil or coco butter is obtained by pressure from the fruit of 
certain coco-palms. It is whitish, of unctuous consistence, with a peculiar 
fatty smell. It is a mixture of several glycerides, containing also free acids. 
Though the frequent subject of investigation, this research into coco-nut 
VOL. XXVIII. PART II. q4c 
