116 Milk and Its Products. 
ble, also, because the bearings are not perfectly ad- 
justed ; and, lastly, the bowl may tremble because 
the machine is not set level or upon a solid founda- 
tion. A second cause of inefficient separation is 
variation in the velocity of the bowl. It is quite as 
important that the bowl run uniformly as it is that 
it attain any given rate of velocity. In this re- 
spect the turbine separators are more likely to be 
at fault than those run by belt power, and separa- 
tors tured by hand are more subject to variations 
than those run by power. 
An engine of ample power, with a good gover- 
nor, and the power transmitted through an interme- 
diate rope belt kept perfectly tightened, with well-oiled 
bearings all around, are the best safeguards to uni- 
form speed. 
Efficieney of separation in centrifugal machines,— 
With the centrifugal separator run under perfect con- 
ditions, there is still a slight loss of fat in the 
skimmed milk. This need not be greater than .1 
of 1 per cent. At the present time it is considered 
that where more than .1 of 1 per eent of fat is left 
in skimmed milk, a centrifugal machine is not doing 
perfect work, and numerous trials have shown that 
the machines of the leading forms can be made to 
reach this poit of effieieney, as may be seen from 
the following table,* giving the average of a large 
number of tests made by several agricultural experi- 
ment stations : 
* Cornell University Agricultural Experiment Station, Bulletin No. 105. 
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