74 ANALYSIS AND ADULTERATIONS OF BUTTER. 



" A quantity amounting to 460 grammes was treated suc- 

 cessively with twice its volume of alcohol of 92 per cent. ; 

 the alcoholic solution on evaporation gave 9 grammes of an 

 oily fat which yielded 79 "7 per cent, of fixed fatty acids, the 

 remainder consisting of glyceriue and the volatile acids. 



" The butter-fat insoluble in alcohol was next treated with 

 twice its volume of warm ether, and allowed to stand for 

 several hours. A white crystalline fat separated, which was 

 thrown on a filter and washed with'a small quantity of ether. 

 The ether was evaporated from both portions, and the spe- 

 cific gravity and fixed fatty acids determined. The crystal- 

 line fat, weighing 90 grammes, had a specific gravity of 

 909'55, and gave 89"50 per cent, of fixed fatty acids. The 

 soluble fat, weighing 350 grammes, had a specific gravity of 

 912'35, and yielded 87'95 per cent, of fixed fatty acids. 



" The portion soluble iu ether was then treated with a mix- 

 ture of alcohol and ether. Nearly one-haK of the fat passed 

 into solution. Both portions were freed from alcohol and 

 ether. The soluble gave 86'50 per cent, of fixed fatty acids, 

 and the insoluble 88'62 per cent. 



" We then proceeded synthetically, by adding to a mixture 

 of beef suet fat and dripping a given percentage of prepared 

 butyrate of glycerin ; 8 per cent, of the butyrin was dis- 

 solved in a fat of a specific gravity of 902-99 by the aid of 

 heat. The specific gravity of the mixture at 100° Fahren- 

 heit was 910'39. The mixture, when treated with alcohol, 

 as in the preceding experiment, was almost completely freed 

 from butyrin, as was shown by the residual fat giving a spe- 

 cific gravity of 903-44. The extractive by alcohol contained 

 a little olein derived from the fat. 



" The conclusion which may be drawn from these results is, 

 that, contrary to the statement made by Berthelot and others, 

 compounds of butyric and the other volatile acids present in 

 butter with glycerine do not exist as simple glycerides, but 



