16 



THE STORY OF MILK 



The Babcock Test.* — By treating a sample of milk 

 with strong sulphuric acid the butter-fat is liberated as 



Babcock test outfit 



an oil. By subjecting the mixture to centrifugal force 

 the light butter oil is separated from the rest of the 



* The Babcock Test is operated as follows: When the milk has been 

 thoroughly mixed and a true sample has been taken the pipette is filled 

 to the mark by sucking the milk into it until it stands a little above the 

 mark on the stem, then quickly placing a dry finger over the end of 

 the pipette and allowing the milk to escape until it just reaches the mark. 

 The quantity thus measured off is 17.6 c.c. The pipette is then emptied 

 into the test bottle by placing the point in the neck and allowing the milk 

 to flow slowly down the inside of the neck, taking care not to lose any 

 of the milk. Blow the last drops out of the pipette into the bottle. 



The measuring glass, holding 17.5 c.c, is filled to the mark with 

 sulphuric acid of a specific gravity of 1.82 to 1.83 and this is poured into 



