DAIRYING 



DAIRYING-Part III 



Cream Separation 



212. Wherever milk is used as a human food some attempt 

 is ordinarily made to skim off the cream. Nearly every civilized 

 person considers cream to be the most valuable part of. milk. A 

 higher price is paid for it than for either butter or cheese, and 

 none of the common milk products are so expensive as cream. 

 On account of this superior value which cream possesses, a con- 

 stant effort has been made in the past, to separate "the cream 

 from milk by the most economical means possible. 



Two forces have been used for this purpose in the past, 

 the force of gravity, and centrifugal force. The former costs 

 nothing, while the application of centrifugal force to cream separa- 

 tion is more or less expensive. Gravity, which works in a per- 

 pendicular direction, was used almost exclusively until about 

 1876, when centrifugal force, which acts horizontally, began to 

 be used for skimming milk. 



High temperatures favor the separation of cream by cen- 

 trifugal force, because hot milk is less viscous than cold, just as 

 hot syrup is thinner than cold syrup, but cream rises slowly by 

 gravity, and on this account milk must be cooled to prevent its 

 souring and coagulating before the cream has all come to -the 

 surface. 



