METHODS OF SAMPLING MILK 3! 



sample, the contents of the jar should be mixed by 

 giving the jar a gentle, rotary motion. Unless this 

 is done regularly each day, the cream that rises be- 

 comes tough, especially where it is in contact with the 

 sides of the jar, and this condition makes it difficult 

 to get a proper sample for testing. This daily mixing 

 also insures the complete solution and distribution of 

 the preservative through the milk, which is an es- 

 sential condition of success in keeping samples. (5) 

 If a composite sample shows any dried or churned 

 cream, the sample should be warmed to 105 or 110 F. 

 for some minutes and then agitated vigorously be- 

 fore drawing the sample for testing. 



AGE OF COMPOSITE SAMPLES WHEN TESTED 



It is advisable to make the fat-test in composite 

 samples, when they have been accumulating for a 

 week or ten days. In any case the limit should be 

 placed at two weeks. The custom practised by some 

 of testing composite samples only once a month should 

 be severely condemned. When samples are kept longer 

 than two weeks, it is more difficult to get a perfectly 

 reliable test for fat. 



PREPARATION OF COMPOSITE SAMPLES FOR 

 SAMPLING AND TESTING 



When a composite sample is to be tested, it is 

 treated like any other sample previous to taking the 

 sample for testing, as has already been described in 

 the first part of this chapter on pp. 20-24. 



