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The Cornell Reading-Courses 



other. It must be remembered that these devices do not cause separation ; 

 they simply aid the centrifugal force. The introduction of these devices 

 has made possible the use of a much smaller bowl for a given capacity. In 

 the evolution of improvement in this direction, the bowls of cream separa- 

 tors have become lighter, and they are consequently easier to turn and to 

 handle. The separator referred to as being the one exception has a long 

 and narrow tube-like bowl in the smaller sizes in which it is manufactured. 



The regulation of the percentage of fat in cream 

 The richness, or the percentage of fat, in cream derived from whole 

 milk by the use of a centrifugal separator is regulated by either a cream 



screw or a skimmed 

 milk screw. Two main 

 facts shotdd be re- 

 membered in this con- 

 nection by the person 

 operating a centrifugal 

 separator when he 

 sets either of these 

 screws. The first of 

 these facts is that the 

 richness of the cream 

 depends on the point 

 in the bowl from 

 which it is drawn. 

 The richest crearri is 

 that which is drawn 

 from the center of the 

 Fig. 82. — A comparison of the amounts of cream from one ^q^\ q^^^ ^^^q richness 

 can of whole milk separated at different temperatures. The ' 1 j- 



pounds of fat in the whole milk and in each pail of cream decreases as the dis- 

 arm practically the same ^^^^^^ ^^^^ the center 



of the bowl increases. The other fact is that the smaller the proportion 

 of cream is to skimmed milk, the richer the cream is in fat. The 

 percentage of fat in cream should be regulated according to the 

 use that is to be made of the cream. Ordinarily for churning 

 purposes, the proportion of cream to skimmed milk should be approxi- 

 mately one to eight, or one to ten. For example, in one hundred poimds 

 of whole milk testing four per cent fat, there are four pounds of fat 

 (100 poimds X 4 per cent = 4 pounds fat). In ten pounds of 

 cream that have been separated from the given 100 pounds of 

 whole milk and that test forty per cent fat, there are approximately four 

 pounds of fat (10 pounds x 40 per cent = 4 pounds). If there is no waste, 



