Theory of Centrifugal Separation 181 
nearest the outside of the bowl. These outlets are made 
of such size in comparison with the size of the bowl, 
the speed of the machine, and the size of the inflow 
tube, that they have a capacity of discharging the 
milk from .4 to .9 as fast as it runs in; the remain- 
ing contents of the bowl are then forced toward the 
center, and find an exit through the cream outlet. 
In this way the milk as it enters is divided into 
two portions: one, the larger, drawn from the ex- 
treme outer portion of the bowl, consisting of 
skimmed milk, and the other, the smaller, escaping 
from the center of the bowl, the cream. A third 
portion also usually accompanies centrifugal sepa- 
ration. A .part of the semi-solid constituents of 
the milk, being heavier than the milk serum, are 
thrown to the outside of the bowl, and adhere to 
the walls in the form of a creamy or gelatinous mass 
which is ordinarily called separator slime. It consists 
mainly of albuminous matter with some fat globules 
adhering, and any particles of dirt or foreign mat- 
ter that may be mechanically mixed with the milk. 
It varies greatly at different times and seasons. 
Usually the -amount is not large, but not infrequently 
it is sufficient to ciog the outlets of the separator 
after a run of an hour or two. The separator slime is 
largely composed of matter deleterious to the qual- 
ity of cream and butter, and its removal is to a 
great extent a purification of the cream. The various 
conditions affecting this operation are as follows: 
Conditions affecting the completeness of separation.— 
The completeness of the separation is dependent upon 
