New York Agricultural Experiment Station. 311 



since it is acid, can contain none, and the insoluble portion, being 

 neutral, can therefore contain none. 



(4) Relation of inorganic constituents to casein in milk. — Without 

 going into a detailed discussion of the history of the different views 

 held by different investigators, it is sufficient for our purpose to state 

 that three general views have been put forward in regard to the rela- 

 tion of inorganic constituents to casein in milk: (1) That milk- 

 casein is combined with calcium (about 1.07 per ct.) to form a salt, 

 calcium caseinate (which is neutral to litmus and acid to phenol- 

 phthalein) ; (2) that casein is chemically combined directly with cal- 

 cium phosphate; (3) that casein is a double compound consisting 

 of calcium caseinate combined with calcium phosphate. 



We have attempted to learn what is the true condition of casein 

 in milk in relation to inorganic constituents, whether it is in com- 

 bination with calcium alone or with some other inorganic base in 

 addition and also whether milk-casein is an acid salt or a neutral 

 salt and, further, whether the insoluble phosphates are in combina- 

 tion with casein or not. 



In studying this problem, we will first give results of work done 

 with 16 samples of fresh milk from 13 individual cows. Determina- 

 tions were made of (a) casein, (b) total phosphorus, (c) soluble 

 phosphorus, (d) insoluble phosphorus (b minus c), (e) insoluble 

 organic phosphorus (0.71 per ct. of the casein), (f) insoluble inorganic 

 phosphorus (d minus e), (g) total calcium, (h) soluble calcium, 



Table II. — Amounts of Projteins, Casein, and Phosphorus in Milk. 



