Theory of Centrifugal Separation. 115 



outlet. In this way the milk as it enters is divided 

 into two portions : one, the larger, drawn from the 

 extreme 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 matters with some fat globules 

 adhering, and any particles of dirt or foreign mat- 

 ter that maj' 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 clog 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 separa- 

 tion. — The completeness of the separation is depend- 

 ent upon the centrifugal force generated, the rate 

 of inflow, the temperature of the milk, and the 

 physical condition of the milk. 



The amount of centrifugal force generated depends 

 upon the diameter of the bowl and the velocity of 

 rotation . 



Roughly speaking, the centrifugal force increases 



