MILK TESTING 



17 



will be considered in another paragraph. Pour the 

 sulphuric acid from the acid measure into the test bot- 

 tle which contains the milk. The acid and the milk 

 should be of nearly 

 the same tempera- 

 ture, 70° F. 



While the acid 

 is poured in, ro- 

 tate the test bot- 

 tle so as to wash 

 all of the milk 

 down from the 

 stem. After the 

 acid is added, take 

 the bottle by the 

 stem and mix 

 the acid and the 

 milk by rotating. 

 The solution be- 

 comes a dark cof- 

 fee color, due to 



^'"■^"Ttue"' **'^* ^^^ ^^^^ charring 

 the sugar. The 

 acid first precipitates the casein and then dissolves 

 it. The acid does not act on the fat. 



The fat is separated from the milk serum by cen- 

 trifugal action. There are a number of different 

 kinds and sizes of centrifugal machines, but they all 

 act on the same principle. The test bottles are 

 placed in the pockets of the centrifugal machine. 



Fig. 6. — Acid measure. 



