54 FOODS AND FOOD ADULTERANTS. 



About 5 grains of solid caustic potash arc then added, and from time to 

 time a few drops of water, to facilitate its solution, the liquid being- 

 stirred all the time. In this manner the butter becomes vapidly sapon- 

 ified. The clear yellowish solution is then freed iivm all alcohol over 

 the water bath and the soap decomposed as already described. Care 

 should be taken to remove all the alcohol, as a small quantity of the 

 fatty acids might bo held dissolved should any alcohol remain, and so 

 lead to an erroneous result. 



Hclincr's method modified by Eeichcrt. 1 Weigh out 2^ grains of dried 

 and filtered butter fat in an Erlenmeyer flask of 150cc. capacity ; add 1 

 grain of solid potassium hydrate and 20cc. of 80 per cent, alcohol. This 

 mixture is kept upon the water bath with constant shaking until the soap 

 obtained no longer forms a foamy, greasy mass. Afterwards 50cc. of 

 water are added to the flask, and the soap, after it has dissolved in water, 

 is decomposed with 20cc. of dilute sulphuric acid (Ice. of pure sulphuric 

 acid to lOcc. of water). The contents of the flask are now subjected to 

 distillation, with the precaution of conducting through it a slow stream 

 of air, in order to avoid bumping, It is also recommended to use a bulb 

 tube with a wide opening 1 , in order to avoid carrying over the sulphuric 

 acid. The distillate, which, especially with fats poor in butter and by 

 rapid distillation, always deposits a little of the solid fat acids, is filtered 

 through a moistened filter paper and collected in a 50cc. flask. After 10 

 to 20cc. are passed over it is poured back into the flask and the distilla- 

 tion is nov* continued until the distillate amounts to exactly 50cc The 

 distillate, which, when the distillation has gone on evenly, forms a water 

 clear liquid, is immediately titrated with decinormal soda lye after the 

 addition of 4 drops of litmus tincture. The titration is finished if the 

 blue color of the litmus remains constant for some time. Six analyses 

 of an artificial butter fat required 10.5cc. of decinormal soda lye to neu- 

 tralize the acid in the distillate. 



The genuine butter gave on three trials 14 50, 14.45, and 14.GOcc., re- 

 spectively, of the decinormal soda. 



Two samples of cocoanut fat required 5.70 and 3.70cc. of soda lye. 



Thirteen samples of pure butter required a mean of 13.97cc. of the 

 decinormal soda. 



All the other fats which are used in the adulteration of butter re- 

 quired a much smaller amount of the decinormal soda for the saturation 

 of the distilled acid. 



In artificial butters the proportion of pure butter and added fat may 

 be calculated from the following formula: 



in which n represents the most probable value of the number represent- 

 ing the quantity of decinormal soda solution required either for pure \l 

 butter or for the fat with which it may be adulterated. When B equals \ 



l Zeit. Anal. Chcm., 1879, pp. 68, et scq. 



