2.2 MODERN METHODS OF TESTING MILK 



tially churned milk, the fat may be redistributed in 

 the milk by warming it to 105° or 110° F. long enough 

 to melt the butter-granules, after which the sample 

 is vigorously shaken, until the fat is evenly distributed 

 through the milk, and then the sample is drawn at 

 once for analysis. 



Dissolving fat in ether. — Another method of treat- 

 ing partially churned milk, previous to sampling, is 

 to shake the milk with 5 per cent, of its volume of 

 ether until the fat-granules are redissolved and then, 

 after further vigorous shaking, to take the sample at 

 once. In this case it is necessary to make a correc- 

 tion by adding to the results 5 per cent, or one-twenti- 

 eth of the result obtained. For example, a milk, 

 treated with 5 per cent, of ether, and giving, on test- 

 ing, 3 per cent, of fat, should have added .15 (5 per 

 cent, of 3), making the corrected result 3.15 per cent. 

 When ether is used, extra care must be observed in 

 mixing the acid and milk, (see p. 58) as the heat de- 

 veloped may cause the ether to boil up out of the 

 neck of the test-bottle. 



Measures for preventing the churning of fat in 

 milk. — It is better to prevent the churning of fat in 

 milk than to be put to the extra trouble required to 

 get a good sample from milk that has in it fat-granules. 

 Cans of milk, when necessarily exposed to much mo- 

 tion in transportation, should be made as nearly full 

 as possible. In the case of bottles of milk sent by 

 mail or express for analysis, the churning of fat may 

 be prevented in the following manner: Fill the bot- 

 tle full of milk to overflowing. Then push in tightly 

 a stopper of cork or rubber in which has been made 



