234 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



making the test. The acid dissolves the solids not fat 

 and liberates the fat from its emulsion, generates heat 

 which causes the fat globules to run together, and in- 

 creases the specific gravity of the serum. The test is 

 made as follows: The temperature of the milk should 





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Fio.33. Modern type of Babcock milk- Fra. 34. Pipette used in Babcock 



testing bottle conforming to the require- testfor measuring milk. 'From Chem- 



ments of the U. S. Bureau of Standards. ical Testing of Milk and Cream, by 



(From Chemical Testing of Milk and R. H. Shaw, U. S. Dept. of Agriculture.) 

 Cream, by R. H. Shaw, U. S. Dept. of Ag- 

 riculture.) 



be between 60 and 70 F. After the milk has been 

 thoroughly mixed, the tip of the pipette is inserted just 

 beneath the surface and filled to the 17.6 c.c. mark. 

 The pipette is then inserted obliquely into the mouth of 

 the bottle and the milk permitted to run slowly down 

 the inside of the neck. When the milk ceases flowing, 

 the pipette is blown into to force out any residue. To 



