CARE OF MILK ON THE FARM 329 



farms where only a few cows are milked. In the first method, 

 the milk is poured into shallow pans and allowed to set in a cool 

 place for about thirty-six hours, during which time the cream 

 rises to the surface. The cream surface, which is exposed to the 

 air, often absorbs objectionable odors and flavors. The greatest 

 disadvantage, however, is the loss of fat in the skim milk, which 

 varies from 0.5 to 1.5 per cent. 



The deep-setting method of separation is the best of the 

 gravity systems, owing to the fact that a better quality of both 

 cream and milk is obtained. As soon as milk is draAvn from the 

 cow, it is placed in a deep but narrow can, and the can set in cold 

 water, preferably with an addition of ice, for twelve hours. The 

 low temperature causes the cream to rise quickly and the separa- 

 tion takes place while the milk is still in good condition. 

 However, by this method about 0.5 per cent of the butterfat 

 remains in the skim milk. 



The water-dilution method is probably the least used, as it 

 results in a loss of butter fat equal to the shallow-pan method 

 and has the further objection of adding a watery flavor to the 

 cream and reducing the value of the skim milk by dilution. 



AVith the centrifugal separator the separation is accomplished 

 in a few minutes while the milk is still warm and perfectly fresh. 

 This is a great advantage in getting a good quality of perfectly 

 sweet cream. The skim milk also is more valuable when fed 

 fresh and warm to calves and young stock. Furthermore, when 

 the milk is fed soon after it is produced the chances of contam- 

 ination are lessened and the bacterial content will ordinaril}^ be 

 much lower than when it is allowed to stand for a considerable 

 length of time. 



The centrifugal method also has the advantage over other 

 methods of separating in that the thickness of the cream can be 

 regulated at will simply by turning the cream screw. 



The centrifugal separator skims to a very small fraction of 

 one per cent, so that practicall}^ no butter fat is left in the skim 

 milk. This, of course, results in a considerable saving and, 

 unless the quantity of milk to be skimmed is very small, the sep- 

 arator is a jDaying investment. There is no hard and fast rule 

 for determining the number of cows a dairyman should milk 

 before it will pay him to buy a separator, but ordinarily, where 

 the herd numbers more than four or five cows, the use of a sep- 

 arator would prove to be economical. 



Size of separator. — The size of the separator required wall 

 depend on the number of pounds of milk produced. However, 



