CHAPTER II 



Methods of Sampling and Preserving Milk 



Too much emphasis can not be placed upon the im- 

 portance of taking for analysis a sample of milk that 

 truly represents the whole body of milk from which 

 the sample is taken. This statement applies equally 

 to any product or by-product of milk that is to be 

 tested. Before a sample for testing is taken, the body 

 of milk from which the sample is to be drawn should 

 be uniform throughout in composition. Several con- 

 ditions may disturb the desired uniformity of compo- 

 sition of a mass of milk, among which are the fol- 

 lowing : 



(1) Separation of fat. 



(2) Partial churning of fat. 



(3) Freezing of milk. 



(4) Souring of milk. 



SAMPLING MILK WHEN FAT HAS SEPARATED 



The rapidity with which fat-globules rise to the 

 surface of milk in the form of cream is well known. 

 Therefore, milk standing at rest soon loses its uni- 

 formity of composition, the upper layers containing 

 more fat than the lower ones. On this account it is 

 always necessary, just before taking a sample of 

 milk for testing, to make sure that the body of milk 

 to be tested has an even composition throughout. 



Milk in which fat separation is slight. In milk 



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