112 Milk and Its Products. 
the milk passes so rapidly through the machine that 
the separation is not complete, and if we reduce the 
inflow to such a point that the skimmed milk outlet 
has a capacity of discharging the milk as fast as it 
flows in, we shall get a separation until the bowl 
becomes filled, and then all of the milk will pass 
out of the skimmed milk outlet in the same condi- 
tion in which it enters the machine. 
The speed of the machine, also, affects the rela- 
tive amount of cream and its percentage of fat. The 
size of the skimmed milk outlet being fixed, the 
faster the bowl is revolved the greater the capacity 
of this outlet will be, so that, the rate of inflow 
remaining uniform, the faster the bowl is revolved 
the less proportional amount of cream we shall have, 
and the richer it will be in fat, and vice versa. It 
must be borne in mind, further, that the speed of 
the bowl is also an important factor in the complete- 
ness of separation, and that if the speed is slackened 
in order to get a greater bulk of cream, there will 
be danger of incomplete separation. 
Most of the machines have arrangements for reg- 
ulating the relative amount of skimmed milk and 
cream without changing the rate of inflow or the 
speed of the machine. In most of the machines 
this arrangement is known as a “cream screw,” and 
affects the amount of cream by placing the cream 
outlet nearer or farther from the center of the bowl; 
the nearer the center the cream screw is turned, the 
thicker will be the cream and the smaller the amount. 
Some of the separators change the proportion of 
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