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 



charring 

 



FIG. 5 -Milk test 

 bottle. 



FIG. 6. Acid measure. 



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. 



