MILK AND ITS PRODUCTS 125 



Maximum. Minimum. 



Water 90.69 80.32 



Fat . . 6.47 1.67 



Casein 4.23 1.79 



Albumen 1-44 .25 



Sugar 6.03 2. ii 



Ash i. 21 .35 



These figures represent quite accurately the maximum 

 and minimum composition of milk except that the maxi- 

 mum for fat is too low. The author has known cows 

 to yield milk testing 7.6% fat, and records show tests 

 even higher than this. 



BUTTER FAT. 



This is the most valuable as well as the most variable 

 constituent of milk. It constitutes about 83% of butter 

 and is an indispensable constituent of the many kinds of 

 whole milk cheese now found upon the market. It also 

 measures the commercial value of milk and cream, and 

 is used as an index of the value of milk for butter and 

 cheese production. 



Physical Properties. Butter fat is suspended in milk 

 in the form of extremely small globules numbering about 

 100,000,000 per drop of milk. These globules vary con- 

 siderably in size in any given sample, some being five 

 times as large as others. The size of the globules is 

 affected mostly by the period of lactation. As a rule the 

 size decreases and the number increases with the advance 

 of the period. In strippers' milk the globules are some- 

 times so small as to render an efficient separation of the 

 cream and the churning of same impossible. 



The size of the fat globules also varies with different 

 breeds. In the Jersey breed the diameter of the globule 



