SEPARATION OF CREAM. 137 



The size of the skimmed- milk outlet is usually made so 

 that it bears a certain relation to the size of inlet, size of bowl, 

 and to the speed of the machine. Most skimmed-milk outlets 

 are made so as to discharge from .4 to about .9 or a little more, 

 of the whole milk that enters the bowl. The remainder is 

 the cream, which is forced to the center of the bowl and dis- 

 charged through the cream outlet. 



Relative Amount and Richness of Milk and Cream 



Obtained. 



The conditions which affect the relative amount of cream 

 may be said to be as follows: 



1. Regulation of the cream or skimmed-milk screw. 



2. Rate of inflow to the bowl. 



3. Speed of the machine. 



4. Temperature of the milk. 



I. Regulation of the Cream or Skimmed-milk Screw. — All 

 modern machines, so far as known, have a device by which 

 the relative amount of skimmed milk and cream can be con- 

 trolled, and consequently the richness of the cream. Some 

 machines have this device in the form of a cream-screw, and 

 others as a skim-milk screw. The cream-screw in most of 

 the machines has a hole on one side of it through which the 

 cream is discharged. If this screw is turned so as to make 

 the hole nearer the center, then the cream will be richer and 

 less in quantity. If turned away from the center, then more 

 and thinner cream will be discharged. In some machines there 

 is a skim-milk screw which serves the same purpose. The 

 method then of regulating the relative amount of cream and 

 skimmed milk works in just the opposite direction; that is, 

 when thicker cream and less of it is wanted, then the milk-screw 

 is turned so as to bring the skimmed-milk outlet nearer the 

 circumference of the bowl. This gives more skimmed milk 

 and consequently less cream. If thinner and more cream is 

 wanted, then the screw is turned in. This causes more milk 

 to flow out through the cream outlet. The Reid hand separator 



