DETECTION OF ADULTERATION 219 



mixed milk and tlie specific gravity to rise above its 

 maximmn (1.034:), this adulteration is difficult to dis- 

 cover, as the considerable variations in normal milk 

 would lead one to expect. It is in these cases that com- 

 parison was formerly made with the stable or herd sam- 

 ples, but, as stated before, these are worth but little in 

 relation to small herds, and even in the case of large 

 ones they are not entirely trustwortliy. AYhen it is pos- 

 sible to compare the figures of inspected milk with the 

 results of the herd test, an opinion can be formed as to 

 how great a percentage of the fat content is lacking, 

 from this fornmla : 



in which F shows the fat percentage in the herd sample 

 and f the fat i)ercentage of the sampk' under suspicion. 



AVhere there is reason for suspicion, the Itest iiu'tlidd 

 for i)r()ving the existence of such adultrration is, 

 in many cases, furnislie<l by the judicial bearing of the 

 persons charged, and the witnesses. In many places, as 

 has already been stated, to prevent such adulterations a 

 minimum standard has been established for the fat con- 

 tent of whole milk. 



[In America, where there are legal standards calling 

 for .'^ to 0.5 per cent, of fat in whole milk, prosecutions 

 for partial skimming or dilution with skimmed milk are 

 not often brought if the sample conies up to this estab- 

 lished standard, although such adulteration may be 

 suspected from a marked disproportion between the 

 fat and the solids not fat. But this proportion is, at 

 best, so variable that it furnishes no definite guide. 

 L. P.] 



It. The dilution of whole milk with water causes an 

 iucreast' of volume and, therefore, a decrease in the per- 

 centage of fat, of solids and of the specific gravity of the 



