CHAPTER X. 



THE DAIEY. 



Milk. Its constituents Conditions affecting its richness. Curdling. 

 The action of bacteria. Cream. The fat globules Modes of 

 raising cream Composition of cream Kipening of cream. Skim- 

 milk. Its composition. Butter. The operation of churning 

 Composition of butter. Butter-milk. Its composition. Cheese. 

 Rennet Operation of cheese-making Composition of cheese. 

 Whey. Its composition. Annatto. Its nature and use. Necessity 

 for cleanliness. 



Milk. The general composition of colostrum, and of 

 ordinary cow's milk, has been already given on p. 117. 



Cow's milk has generally a specific gravity of 1*032, 

 the extremes being about 1*028 and T035. As the 

 removal of cream raises the specific gravity, which can 

 be brought back to the normal point by the addition of 

 water, no safe conclusion as to the quality of milk can be 

 based on this indication. 



The albuminoids of milk are chiefly composed of two 

 constituents of similar composition, casein and albumin. 

 Casein is coagulated by the addition of acids, or by 

 rennet, but not by boiling. Albumin is not coagulated 

 by rennet, or by most acids, but is coagulated by heat. 

 In colostrum albumin largely preponderates, so that the 

 milk coagulates on boiling ; in ordinary cow's milk the 

 albumin forms about one-eighth of the total albuminoids. 



The fat of milk chiefly consists of the glycerides of 



