DETECTION OF ADULTERATION 223 



specific gravity of the solids (m) must be increased. The 

 specific gravity of adulterated milk can vary consider- 

 ably, often it is nearly normal, but frequently it is 

 slightly diminished. Feser has given the following ex- 

 ample of such adulteration : 



The unadulterated milk had 3.95 per cent., fat; 8.9 

 per cent., solids not fat; 1.031 specific gravity; by par- 

 tial skimming, it was changed to 2.19 per cent., fat; 

 about 8.9 per cent., solids not fat ; 1.034, specific gravity ; 

 by the addition of water it was further changed to 1.21 

 per cent., fat; about 8 per cent., fat free solids; 1.0305, 

 specific gravity. 



Decisive points for determining if such adulterations 

 exist are the low solid contents, the low fat per cent., 

 the almost normal specific gravity of the milk, the in- 

 creased specific gravity of the solids (m) which, in the 

 above example, was changed from 1.305 to 1.473, and in 

 the low specific gravity of the whey. If nitrates are 

 proven in the milk there is further support for the con- 

 clusion that it is watered. 



When a sample of adulterated milk can fairly be 

 compared with another which is known to be unadulter- 

 ated (samples taken from the same dealer the same day, 

 milk of a large herd, etc.) [or with an accepted stand- 

 ard] one can form an opinion of the extent of the 

 adulteration by means of a formula derived from Bohm- 

 lander : 



M=--?x w w 



E == 100 



(-) 



M shows the quantity of water added to 100 grm. of 

 rnilk; "VV is the per cent, of water in the unadulterated 

 and w in the adulterated, or suspected, sample ; R and r 

 are the percentages in these two samples of solids not 



