62 



MAINE AGRICULTURAL EXPERIMENT STATION. 



solves all the solids contained in the milk except the fat; this 

 is separated from the solution by centrifugal force. 



In churning, water and small quantities of casein and other 

 solids separate with the butter fat and remain incorporated with 

 it, so that after the salt is added butter contains only 80 to 87 

 per cent butter fat. In the Babcock test the fat is separated as 

 pure butter fat, and contains neither water, salt nor casein. 



A good quality of butter contains about 85 per cent butter 

 fat, and this is the percentage commonly used in calculating but- 



TT 



A 



n&c 



\ 



Fig. 1. 



Fig. 2. 



Fig. 3. 



^=> 



FIG. 4. 



ter fat to its equivalent in butter. Suppose, for example, milk 

 tests 4.25 per cent fat, 100 pounds of such milk contains 4.25 



