178 THE AMERICAN FARMER. 



ness, requires certain essentials, in the knowledge and practice of which its highest possibili 

 ties may be attained. These essentials may, perhaps, be briefly summarized in a knowledge 

 of the nature of milk and its treatment in various relations; its manufacture into different 

 dairy products, their care and preservation; a knowledge of the art of successful breeding, 

 breeding for a specific object; the management of dairy cattle in health and disease; the pro 

 duction of their food, etc. 



Milk is the liquid secreted by the mammary glands of female mammalia for the nourish 

 ment of their young, and although the milk of each species of animals of this order has its 

 peculiarities, differing somewhat from that of every other species, it is always a white, opaque 

 fluid, sometimes of a bluish and sometimes of a yellowish tint, having a slight, agreeable 

 odor and sweet taste. It contains a fatty substance, which forms butter; casein, which forms 

 cheese, and a watery residuum, called serum or whey, in the manufacture of cheese. 



The fatty globules, commonly known as butter globules, are generally round in form 

 and of unequal size, varying from -^ to -^ of a line in diameter. Under the microscope 

 they are seen to float about in the serum or watery portion of the milk. They are so very 

 minute that they readily filter through the finest paper. The fatty or butyraceous matter in 

 milk varies, according to its richness, from two and a half per cent, to six and a half per 

 cent, or more of its weight; the caseous or cheesey matter from three to ten per cent., and the 

 watery or serous matter called &quot; whey,&quot; from eighty to ninety per cent. When milk is per 

 mitted to stand undisturbed for a time, the fat or butter globules rise to the lop and form a 

 layer of cream; this separation of fat and serum is, however, never complete, each retaining 

 a portion of the other. 



If cream rose to the surface of milk entirely free from other elements, it would 

 appear in the form of pure butter, and would not require the process of churning to separate 

 it from the other matter which it contains. A high temperature hastens the separation of 

 the caseous matter or curd from the whey. This separation sometimes takes place so rap 

 idly from the effects of great heat or sudden changes in the atmosphere that sufficient time 

 is not allowed for the butter globules to rise to the top, and hence they become mixed with 

 the curd. Milk, upon standing, separates into curd and whey, becoming sour by the change 

 of its sugar of milk into an acid known as lactic acid. It is owing to the presence of this 

 sugar, and the chemical changes that take place in consequence, that milk undergoes the dif 

 ferent degrees of fermentation. An intoxicating liquor may be made from milk by ferment 

 ing it, followed by distillation, which produces pure alcohol. 



The Tartars and Arabs make much of their spirituous liquors in this way from camel s 

 milk. 



Relative Nutritive Talue Of Milk. It will be seen by a cursory examination of 

 the following table, given by Dr. Bellows, that milk, as an article of food, is not usually 

 rated at its actual worth. It gives the comparative nutritive value of several articles of food 

 in their natural state, and will be found convenient for reference and comparison: 



THE RELATIVE NUTRITIVE VALUE OF MILK. 



NITRATES. CARBONATES. PHOSPHATES. WATER. 



Milk of Cow, ... 5.0 8.0 1.0 86.0 



Beef, .... 15.0 * 30.0 5.0 50.0 



Lamb, .... 11.0 35.0 3.5 50.5 



Mutton, . . .12.5 40.0 8.5 44.0 



Pork 10.0 50.0 1.5 38.5 



Codfish, .... 14 very little. 5 to 6 79 



Trout, . .17 very little. 5 to 6 75 



White of eggs, . . .15* none. 4| 80 



