132 MODERN METHODS OF TESTING MILK 



Example: A sample of milk contains 12.5 per cent, 

 of solids and has a specific gravity of 1.031 ; 

 — what is the specific gravity of the milk-solids? 



100 X 1.031— 100 , _^. . 12.5 , ,_ 

 _^ = 3.006, 12.5-3.006 = 9.49^. ^.^^4=^-32 



This calculation may assist in determining whether 

 a sample of suspected milk has been adulterated. The 

 variations of the specific gravity of milk-solids is slight, 

 ranging between 1.25 and 1.34. Milks richer in fat 

 have solids of lower specific gravity. The specific 

 gravity of milk-solids is not changed by watering milk, 

 but is increased by removing fat or by addition of 

 skimmed milk. Hence, milk whose solids have a 

 specific gravity above 1.34 is suspected of being 

 skimmed, while a specific gravity above 1.40 is re- 

 garded as clear evidence of skimming. 



