26 



DAIRY CHEMISTRY 



way the milk for six days may thus be measured 

 directly into the test bottles, and then tested. 



24. Testing Skim Milk. — In testing skim milk the 

 special test bottle devised by Farrington, with the 



small neck and the side tube for 

 the addition of the acid, should 

 be used (see Fig. 10). Each 

 division on the neck represents 

 .05 of a per cent. In using these 

 bottles, it must be remembered 

 that the small amount of fat ob- 

 tained in the neck is not neces- 

 sarily all of the fat in the skim 

 milk, because some of it may be 

 present in such a fine state of divi- 

 sion that it is not brought up into 

 the neck. Hence the results are 

 usually slightly lower than those 

 obtained by chemical analysis. 

 This, however, does not seriously 

 impair the test. When the test 

 shows only a trace of fat, the 

 Fig. 10.— Skim milk test butter maker can feel satisfied that 

 he is doing good work. 



25. Sampling Frozen Milk. — When a can of milk 

 freezes, the ice forms on the outside and there is 

 usually a central part that does not freeze. The un- 

 frozen part is richer in fat and solids than the frozen 

 part. The ice in the center of a can is richer in milk 

 solids than the ice of the outer portions. When 



