FATS. 75 



to tlic point of fusion in tlie fats of different animals. Chevreul 

 describes the olein of human fat as a colourless oil, devoid of 

 odoiu', and of a sweetish taste, which retains its fluid state at 

 25°. At a lower temperature it assumes a crystalline acicular 

 form. Its specific gra^dty at 59° is 0-913. One hundred parts 

 of boiling alcohol tlissolve 123 of olein; when the solution 

 cools to 170°, it becomes turbid. It is readily soluble in ether, 

 btit perfectly insoluble in water. It burns with a clear flame. 

 It dissolves camphor, phosphorus, selenium, the ethereal oils, 

 benzoic and many other organic acids. Its composition is re- 

 presented by the formula C,,^ H^. Oj^, and is composed of 



1 Atom glycerin . . Cg H^ O5 -| 



2 Atoms oleic acid . Cgg H^g Og i-= C94 Hg^ 0,3 

 2 Atoms water . . H.^ Oa-I 



c. Butyric and its allied acids. Butter contains four volatile 

 acids, which stand in a very simple relation to each other, 

 namely, butyric acid = C^ H^ O^, caproic acid = Cj^^ Hj„ O^, 

 capryllic acid = C,g Hj^ O^, and capric acid = C^,^ H„,, O^. 

 Butter sometimes affords, instead of butyric and caproic acids, a 

 distinct acid, vaccinic acid, which appears to be equal to the 

 sum of those two acids, minus 1 atom of oxygen, and is very 

 readily decomposed into them. Two of these acids, the capryUic 

 and vaccinic, were discovered only a few months ago, by Lerch, 

 a German chemist. The following is the method that he gives 

 for their separation : 



" Fresh butter is completely saponified with potash in a still, 

 the soap decomposed in the vessel with dilute sulphuric acid, 

 the head then luted on, and the aqueous liquid drawn off to 

 within a fourth. Fresh water is then added to it, which is 

 again distilled off, and this operation continued as long as the 

 water which passes over possesses any acid reaction. In this 

 manner the volatile fat acids are carried over just as the essen- 

 tial oils ; the action of the atmosphere is moreover entirely ex- 

 cluded. From four to five pints of a milky liquid are obtained 

 from a pound of butter, on the surface of which float drops of 

 oil and particles of hard or smeary fat. The distilled water is 

 immediately saturated in the receiver with barytic water, and 

 allowed to stand well closed till the end of the distillation. When 

 the distillation is finished, the still is cleansed, and the liquid 

 saturated with barytic water, evaporated in it, with the head on. 



