CHAPTER II 

 COMPOSITION OF MILK 



Appearance. Milk as secreted is opaque and 

 white in appearance. Normally it usually has a 

 slightly yellowish tinge, due to the fat globules 

 it contains. The white color is due to suspended 

 particles interfering with the passage of the 

 light. Skim-milk, or milk from which the fat 

 has been removed, has a bluish tinge. Milk has 

 a sweet taste when first drawn owing to the pres- 

 ence of the milk sugar. 



Specific gravity. Milk is heavier than water, 

 having a specific gravity of about 1.029 to 1.033. 

 This means that if a vessel held exactly 1.000 

 pound of water, this same vessel would hold from 

 1.029 to 1.033 pounds of milk. 



The two parts of milk. Milk may be consid- 

 ered as consisting of two parts, viz.: the fat and 

 the serum. One hundred pounds of milk ordi- 

 narily contains about 3.7 pounds of fat. The 

 serum in this amount, consisting of all the con- 

 stituents of the milk except the fat, would 

 therefore weigh 96.3 pounds. 



There is no chemical union between the fat and 



15 



