610 



TESTING FOR BUTTERFAT 



Table 103. Continued. 



TESTING MILK, CREAM, SKIM MILK AND BUTTER- 

 MILK FOR BUTTERFAT 

 Volumetric Methods 

 The Babcock Test 



Principle of Babcock Test. The principle of the Babcock test 

 is based on the fact that when sulphuric acid in sufficient strength 

 and amount is added to milk, cream or other dairy product, the acid 

 breaks down the non-fatty constituents without materially affecting 

 the fat. The action of the acid, together with the heat generated, 

 destroys the emulsion of fat-in-milk serum, causing the fat to sep- 

 arate out. The completeness of this separation is facilitated by sub- 

 jecting the mixture of acid and milk to centrifugal force. 



In order to make possible the ready measurement of this prac- 

 tically pure, separated fat in terms of per cent, the neck of the test 

 bottle, in which the fat appears in the finished test, is graduated. 

 Each one per cent graduation has a capacity of .2 cubic centimeter. 

 The specific gravity of butterfat at about 135 degrees F., which is 

 the temperature at which the test is read, averages .9. The .2 cubic 

 centimeter of butterfat therefore weighs .2 X .9 = .18 grams. In 



