No. G. DEPARTMENT OF AGRICULTURE. US 



In giving (lie description of any iudividnal chemical compound in 

 couneclioii with tlie chemistry of milk, we shall not need to repeat 

 tiie description when we come to consider that compound in con- 

 nection with the products of milk; for, it will be found, the descrip- 

 tion given here will apply to the same compound wherever we find 

 it. The word milk, as we shall use it, refers always to cows' milk, 

 unless otlierwise stated. 



2. Water. 



1. Chemistry. — The water present in milk and its products, how- 

 ever much its presence may be disguised, is one and the same com- 

 pound of hydrogen and oxygen, with which we are everywhere fa- 

 miliar. The water in milk and its products is simply plain, common 

 water, possessing no chemical peculiarities to distinguish it from 

 water found anywhere else. It is only ordinary water in the com- 

 pany of other chemical individuals. 



(2.) Purpose.- — The water in milk serves the purpose of holding in 

 solution the soluble constituents of the milk. It also acts as a 

 diluect, better fitting the mixture as animal nutriment. 



(3.) Amount of Water in Milk. — The amount of water contained 

 in milk varies considerably, depending upon a variety of conditions, 

 such as individuality, breed, stage of lactation, age, character of 

 food, amount of water dru«k, condition of health, etc. 



(a.) Single Milkings. — Taking single milkings of individual cows, 

 vve maj find the amount of water in 100 pounds of milk varying from 

 82 to 00 pounds or more, corresponding to 10 to 18 pounds of total 

 solids. 



(b.) Lactation Period of Single Cows. — In case of milk from single 

 cows for an entire period of lactation, the variation of water may 

 range from 84 to 89 pounds, corresponding to 11 to 16 pounds of 

 total solids. 



(c.) Herds. — Taking milk from herds of cows, the variations of 

 water are within narrower limits, usually ranging from 86 to 88 

 pounds in 100 pounds of milk, corresponding to 12 to 14 pounds of 

 total solids. 



r?i the case of average milk, as found in the United States^ 100 

 pounds of milk contain from 87 to 87 l-Jf- pounds of ivater, correspond- 

 ing to 12 3-Jf, to 13 pounds of solids. 



(d.) Breed. — As regards the influence of breed of cow upon the 

 proportion of water in milk, the following figures, taken from the 

 Geneva (N, Y.) Station records, serve as a fair illustration: 



