24 Testing Milk and Its Products. 



30. Partially churned milk. A second difficulty 

 sometimes met with in sampling whole milk arises from 

 the fact that a part of the butter fat may be separated 

 in the form of small butter granules, by too zealous mix- 

 ing or by reckless shaking in preparing the sample for 

 testing. This will happen most readily in case of milk 

 from fresh cows or of milk containing exceptionally 

 large fat globules. When some of the butter granules 

 are thus churned out, they quickly rise to the surface of 

 the milk after pouring and cannot again be incorporated 

 in the milk by simple mixing; it is, therefore impossi- 

 ble to obtain a fair sample of such milk for testing 

 without taking special precautions which will be ex- 

 plained in the following. The granules of butter may 

 be so small as to pass into the pipette with the milk and 

 the quantity measured thus contain a fair proportion 

 of them, but they will be found sticking to the inside 

 of the pipette when this is emptied, and thus fail to be 

 carried into the test bottle with the milk. 



A similar partial churning of the milk will sometimes 

 take place in the transportation cans. When such milk 

 is received at the factory, the butter granules are caught 

 by the strainer cloth through which the milk is poured, 

 and are thus lost both to the factory and to the farmer. 

 This separated fat cannot be added to the cream or to 

 the granular butter, without running the risk of mak- 

 ing mottled butter, and it will not enter into the sam- 

 ple of milk taken for testing purposes. 



When milk samples are sent by mail or express in 

 small bottles, or carried to the place of testing, they 

 often arrive with lumps of butter floating in the milk 

 or sticking to the glass. This churning of the milk can 



