DAIRY CHEMISTRY 



3. Milk Solids. — When milk is evaporated to dry- 

 ness, the water is expelled and the milk solids are 

 obtained. Milk solids are a mechanical mixture of 

 fat, casein, albumin, milk sugar, and ash. Normal 

 milk contains about 13 per cent of solid matter ; some 

 samples contain as low as 12 and a few as high as 

 14 per cent. The amount of milk solids varies pro- 

 portionally with the fat content of the milk, the higher 

 the per cent of fat the larger the amount of solids. 



In the chemical analysis of milk, the solids are 

 obtained by evaporating a weighed quantity of milk 

 to dryness in a small dish which has previously been 

 carefully weighed on a very delicate balance. The 

 weight of the milk solids is then obtained and the 

 percentage amounts calculated. 



Example 



Weight of milk + dish 

 Weight of dish 

 Weight of milk 



Weight of dish + solids 

 Weight of dish 

 Weight of milk solids 



10.51 : 1.346 : : 100 : x. 



1.345 X 100 



Grams 



23.360 

 12.850 

 10.510 



14.195 



12.850 



1.345 



. . ^^ - = 12.80 per cent solids. 

 10.51 



100 - 12.80 = 87.20 per cent water. 



Fio.l.-Determining the solids ^^'^ P^'^ °^^* °f ^^^^^ ^^^ 

 in milk. milk is obtained by subtract- 



