MILK — ITS PROPERTIES AND COMPOSITION 3 



The specific heat of milk is less than that of water; 

 that is, it requires less heat to warm a definite amount of 

 milk one degree. It also takes less ice to cool a certain 

 volume of milk one degree than it does to cool the same 

 quantity of water one degree. The specific heat of milk 

 is, according to Fjord, 0.94; the specific heat of cream is 

 about 0.7, depending upon the percentage of fat it con- 

 tains. Rich cream has a lower specific heat than poor 

 cream. 



The maximum density of milk is not, like water, at 

 4° C. (39.2° F.), but at about 32.9° F. The boihng point 

 is a trifle higher, and the freezing point a trifle lower than 

 that of water. 



Composition of Milk. — Probably no other food found 

 in nature, except meat, is subject to such great variation 

 in composition as is milk. The average composition of 

 American milk, according to Babcock,^ is: 



Water 87.17 



Fat 3 ■ 69 » 



Casein 3.02 



Albumen .53 



Sugar 4 . 88 



Ash 71 



The milk of individual animals varies from day to day, 

 and varies as the period of lactation advances. However, 

 the mixed milk from a large herd is not subject to very 

 great variations, but the milk of one herd may differ greatly 

 from that of another herd, due to the breed of the cattle. 

 The constituents subject to the greatest variation are the 

 fat and casein. The following table- shows this: 



1 Farrington and WoU — Testing Milk and Its Products. 



2 Van Slyke — Science and Practice of Cheese flaking. 



