218 MILK HYGIENE 



One has only to subtract the fat percentage found from 

 the computed percentage of total solids. The percent- 

 age of fat (p) in the total solids is easily computed 

 according to the formula : 



p = -|- X 100 

 To use the above illustration : 



3.55 



■ 12.697 



X 100 = 27.95 



Likewise, it is quite easy to determine the specific 

 gravity (m) of the dry milk solids by a simple computa- 

 tion, according to this formula : 



St 



™ ~ St — (100s — 100) 

 Using the same illustration again : 



1.0327 X 12.697 13.112 



"1.0327X12.697— (103.27 — 100) 13.112 — 3.27 



: 1.332 



The specific gravity of the dry solids of whole milk 

 varies, according to the fat content, between about 1.31 

 and 1.36. 



V. ADULTERATION AND ITS DETECTION. 



The most frequent adulterations of whole milk con- 

 sist in partial skimming, dilution with skimmed milk, 

 dilution with water or a combination of these. Skimmed 

 milk is adulterated by the addition of water, and cream 

 by starch, flour, etc. 



a. Partial skimming of whole milk or dilution with 

 skimmed milk produce the same result; in both cases 

 the fat content is lessened, while the percentage of solids 

 not fat is increased very slightly, and the specific gravity 

 is increased. If the skimming is not so great as to cause 

 the fat percentage to fall below the minimum limit for 



