The Lactometer and its Application. 103 



extent of adulteration of a sample of milk. A list of 

 legal standards for milk in this country and abroad is 

 given in the Appendix. These standards determine the 

 limits below which the milk offered for sale within the 

 respective states must not fall. Legally it matters not 

 whether a sample of milk offered for sale has been 

 skimmed or watered by the dealer or by the cow; in the 

 latter case, the cows producing the milk are of a breed 

 or a strain that has been bred persistently for quantity 

 of milk, without regard to its quality. In most states 

 the legal standard for the fat content of milk is 3 per 

 cent., and for solids not fat 9 per cent. There are, how- 

 ever, cows which normally produce milk containing only 

 2.5 to 2.8 per cent, of fat, and less than 8.5 per cent, 

 solids not fat. Such milk cannot therefore be legally 

 sold in most states in the Union, and the farmer offering 

 such milk for sale, even if he does not know the compo- 

 sition of the milk produced by his cow, is as liable to 

 prosecution as if he had directly watered the milk. By 

 mixing the milk of several cows, the chances are that the 

 mixed milk will contain more fat and solids not fat than 

 called for by the legal standard; if such should not be 

 the case, cows producing richer milk must be added to 

 the herd so as to raise the quality of the herd milk up to 

 the legal standard. 



122. The specific gravity of the milk solids. A calcula- 

 tion of the specific gravity of the milk solids is of consid- 

 erable assistance in interpreting the results of analyses 

 of suspected milk samples. The milk solids vary but 

 slightly in specific gravity, viz., between 1.25 and 1.34, 

 the richer milks having solids of low specific gravities. 



