CHAPTER X. 



THE DAIRY. 



The constituents of milk — The conditions affecting its richness — The fat 

 globules — Modes of raising cream — Composition of cream — Composi- 

 tion of skim-milk — Churning — Composition of butter — Butter-milk 

 — Manufacture of cheese — Composition of cheese — "Whey — Necessity 

 for cleanliness. 



Milk. — The general composition of colostrum, and of 

 ordinary cow's milk, has been already given on p. 96. 



The albuminoids of milk embrace two constituents of 

 similar composition, casein and albumin. Casein is coagu- 

 lated 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 but 

 one-ninth of the total albuminoids. 



The fat of milk chiefly consists of the glycerides of 

 palmitic and oleic acid. The glycerides of stearic, myristic, 

 lauric, capric, capryllic, caproic, and butyric acid are also 

 present in small quantity. The last four of these acids 

 are, when in the free state, more or less soluble in water. 

 The glycerides of oleic acid and of the soluble fatty acids, are 

 fluid fats at ordinary temperatures, the remaining fats are 

 solid. The proportion of fluid and solid fats varies some- 



