The Lactometer and Its Application. 113 



ing the 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 de- 

 termine 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, however, cows which at times 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 composition of the milk produced by his cows 

 is liable to prosecution just 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 qual- 

 ity of the herd milk up to the legal standard, or the 

 cows giving very thin milk must be disposed of. 



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

 tion of the specific gravity of the milk solids is of considerable 

 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 sol- 



