NEW YORK MILK COMMITTEE,, , 101 



limit of milk solids from 12 to 11.50 per cent, we will mention 

 briefly some of the more important general principles that have 

 formed a basis in fixing minimum limits of purity for market 

 milk. 



In legally defining normal or pure milk on the basis of its 

 percentage composition, it has been customary to select two 

 factors, fat and solids, and to fix for each the lowest permissi- 

 ble limit. Two different factors have been selected, because 

 more complete protection is obtained than if one alone were used 

 since the percentage of fat and of solids are somewhat inde- 

 pendent and do not vary together uniformly. For example, 

 taking normal milk containing 5 per cent of fat and 14.5 per 

 cent of solids ; it would require the addition of 66 pounds of 

 water to 100 pounds of normal milk before the percentage of 

 fat is reduced to the lowest legal limit of 3 per cent, but the 

 addition of only 1 pounds of water would reduce the solids 

 below the permissible limit of 12 per cent and the diluted milk 

 would still contain 4 per cent of fat. The basis of solids in 

 addition to fat affords, therefore, added protection against 

 dilution by water. 



Now, the chief purpose of a legal definition of normal milk 

 or of adulterated milk is to prevent, or rather limit, the two 

 most common forms of adulteration (1) addition of water and 

 (2) reduction of fat percentage by removal of cream or by 

 addition of skimmilk. It is possible, however, within certain 

 limits, to manipulate milk rich in fat both by watering and by 

 skimming or addition of skimmilk so that it is difficult and often 

 impossible to prove the fact of such manipulation by examina- 

 tion of the milk. 



It is thus seen that in attempting, on the basis of fat and 

 solids, to fix a line of division between milks that shall be re- 

 garded as pure and as adulterated, two general difficulties are 

 met, because normal milk varies so widely in composition, and 

 the relation of fat to solids also varies decidedly. On the one 

 hand, the lowest limits for purity must be placed high enough 

 to prevent too great opportunity for manipulating milks above 

 average richness by watering or skimming. On the other hand, 

 the minimum limits must not be placed so high as to put in the 

 class of adulterated milk the normal product of too many herds 

 of cows. In framing a practicable legal definition for milk, 



