DETECTION OF ADULTERATION 219 



mixed milk and the specific gravity to rise above its 

 maximum (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 trustworthy. When 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 formula : 



x = 100 X ^- 



in which F shows the fat percentage in the herd sample 

 and f the fat percentage of the sample under suspicion. 



Where there is reason for suspicion, the best method 

 for proving the existence of such adulteration is, 

 in many cases, furnished by the judicial hearing 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 3 to 3.5 per cent, of fat in whole milk, prosecutions 

 for partial skimming or dilution with skimmed milk are 

 not often brought if the sample comes 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.] 



b. The dilution of whole milk with water causes an 

 increase of volume and, therefore, a decrease in the per- 

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



