12 Testing Milk and Its Product*. 



and three per cent, of fat, the niilk serum will make up 

 97 per cent, of the milk, and the serum solids, . y 9 7 =9.28 

 per cent, of the milk serum. 



16. Water. The amount of water contained in cows' 

 milk ranges from 82 to 90 per cent. Normal cows' milk 

 will not as a rule contain more than 88 per cent, of water, 

 nor less than 84 per cent. In states where there are laws 

 regulating the sale of milk, as is the case in eighteen 

 states in the Union (see Appendix}, the maximum limit 

 for water in milJC in all instances but one (South Carolina) 

 is 88 per cent. ; the state mentioned allows 88.5 per cent, 

 of water in milk offered for sale within her borders. The 

 effect of fraudulently increasing the water content of 

 milk by watering is considered under Adulteration of 

 Milk (118). 



17. Fat. The fat in milk is not in solution, but sus- 

 pended as very minute globules, which form an emulsion 

 with the milk serum; the globules are present in immense 

 numbers, viz., on the average about one hundred million 

 in a single drop of milk; a quart of milk will contain 

 about two thousand billions of fat globules, a number 

 written with thirteen ligures. The size of the globules 

 in the milk from the same cows varies according to the 

 stage of the period of lactation, the globules being largest 

 at the beginning of the lactation period, and gradually 

 decreasing in size with its progress. Different breeds of 

 cows have fat globules of different average sizes; the 

 Channel Island cows are thus noted for the relatively 

 large fat globules of their milk, while the Lowland 

 breeds, the Ayrshire, and other breeds have uniformly 

 smaller globules. The diameter of average sized fat 



