110 Milk and Its Products. 
directly in proportion as the diameter is increased and 
directly with the square of the velocity. The larger 
the bowl, then, and the greater the speed, the greater 
the centrifugal force and the more complete the sep- 
aration. The rate of inflow of milk affects the 
separation, because the separation is more complete 
the longer the milk is subjected to the centrifugal 
force, and the slower the milk flows into a given- 
sized bowl the longer any particle will be in flowing 
through it and the more completely will the cream 
be separated. The temperature of the milk affects 
the fluidity of the fat globules and their ease of mo- 
tion upon the other particles of the milk; the warmer 
the milk the more easily are they separated. <A 
temperature of 76° to 98° F. is the one commonly 
employed because of the effect upon the texture of 
the butter. It is desirable that the milk should be 
separated at as low a temperature as possible without 
interfering with the completeness of the separation, 
so that, other things being equal, that separator is the 
best that separates the milk at the lowest tempera- 
ture. The physical condition of the milk affects 
separation by the centrifugal in the same ways that 
gravity creaming is affected, but to a very much 
slighter degree. Small-sized fat globules, viscosity 
of the milk, and coagulation of part of the casein 
by incipient fermentations, all tend to make separa- 
tion more difficult; but in a majority of cases, un- 
less the milk is so sour as to be coagulated, it may 
be completely creamed with a centrifugal separator, 
but will require a slower feeding (a reduction of 10 
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