318 THE CHEMISTRY OF DAIRYING 



similar to that of cow's milk, but it contains a somewhat larger 

 percentage of fat. 



As it is frequently necessary to substitute cow's milk for 

 mother's milk, the comparison of these two is of special 

 interest and importance. The percentages of fat and of total 

 solids are about the same in each. The most obvious difference 

 is in the relative proportions of proteins and sugar. Mother's 

 milk, it will be seen, contains less of the former and more of 

 the latter. But it is the nature of* the proteins rather than the 

 total amount that is of the greatest importance. Cow's milk 

 contains nearly three times as much casein as mother's milk, 

 and only about half the percentage of albumin. When cow's 

 milk is given to infants, the casein becomes curdled in the 

 stomach, and forms clots which are not easily digested. They 

 are liable to set up inflammation of the stomach and bowels. 



Bottle Milk for Infants. In order to prevent the 

 disastrous effects mentioned above, cow's milk is usually 

 diluted with two or three times its volume of water. The 

 percentage of casein is thus reduced to about the same as is 

 found in mother's milk. The percentages of all the other 

 constituents are reduced in the same proportion. The infant is 

 therefore compelled to absorb about three times the amount of 

 liquid in order to obtain the same amount of nourishment. 

 The excessive dilution may be partly compensated by addition 

 of sugar, but this, it is said, gives rise to acidity, and the 

 insufficiency of fat has been mentioned as a cause of 

 " rickets." It is advisable, therefore, to add some cream 

 and less sugar than is commonly used. 



A very fair imitation of mother's milk can be prepared as 

 follows : 



The cream is separated from two parts of cow's milk, and 

 the casein in the separated milk is then coagulated by addition 

 of acid preferably lactic acid, or phosphoric acid, if it can be 

 obtained perfectly pure. The curd is then broken up and 

 strained off, and the acidity of the whey is neutralised by 

 addition of calcium carbonate (precipitated chalk). The whey 

 and cream from the two parts of milk are then mixed with one 

 part of fresh whole milk. The minimum amount of acid 



