190 Milk and Its Products 
bowl run uniformly as it is that it attain any given 
rate of velocity. In this respect the turbine separators 
are more likely to be at fault than those run by belt 
power, and separators turned by hand are more subject 
to variations than those run by power. 
An engine of ample power, with a good governor, 
and the power transmitted through an intermediate rope 
belt kept perfectly tightened, with well-oiled bearings 
all around, are the best safeguards to uniform speed. 
Efficiency 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 should not be greater than .1 
of 1 per cent. At the present time it is considered 
that where as much as .1 of 1 per cent of fat is left 
in the skimmed milk a centrifugal machine is doing 
such poor work that its use in a commercial plant would 
be unwarranted. The following tables* taken from the 
average of a large number of tests made‘by several agri- 
cultural experiment stations may be ‘taken as repre- 
senting the degree of efficiency that had been attained 
by the leading manufacturers at the time when separa- 
tors first came into general use (1890-95) and the first 
table is compiled wholly from American sources. At 
the present time no separator should be kept in use 
that will leave more than two or three hundredths of 
one per cent of fat in the skimmed milk in a series of 
tests running day after day under ordinary factory 
conditions. 
*QCornell University Agricultural Experiment Station, Bulletin No. 105. 
