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. 
ReELatTIvE AMOUNT AND RICHNESS OF MILK AND OREAM 
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. 
1. 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 
