BUTTER-MAKING. 



CHAPTER I. 



COMPOSITION OF MILK. 



Definition. — Normal milk is a liquid secreted in special 

 glands of all females belonging to the mammalian group. It 

 is composed chiefly of water, proteids, fats, sugar, and minerals. 

 Coloring-matters and gases and some organic acids are found 

 in small quantities. 



All normal milk from the different classes of animals, such 

 as mare, buffalo, goat, ewe, ass, and cow, has a general resem- 

 blance in that it all contains water, fat, proteids, sugar, and 

 ash. But milk from different animals varies in the relative 

 proportions of its constituents. The chemical and physical 

 properties are not alike. Human milk, when treated with 

 half its volume of ammonium hydrate and the mixture kept 

 at a temperature of 60° centigrade for about twenty minutes, 

 assumes an intense red color. Cow's milk turns faintly yellow 

 if treated in the same way. This test was reported by Unikoff, 

 of St. Petersburg, at the meeting of the Medical Section, Royal 

 Academy of Medicine, in Ireland. The various kinds of milk 

 also differ from each other in their behavior towards rennet. 

 Richmond has divided milk into two classes: Class I includes 

 milk from the ewe, buffalo, goat, and cow. When rennet is 

 added to the milk from these animals, the casein coagulates into 

 a firm curd. Class II includes human milk, milk of the ass, 

 and mare. When rennet is added to the milk of these animals, 

 a soft curd or none at all is formed. The latter class seems 



