138 Milk and Its Products. 
motion of the particles and the motion of the churn 
must not be confounded. If the motion of the churn 
is increased so that sufficient centrifugal force is gen- 
erated to cause the particles of cream to partake of 
Fig. 16. Barrel power churn. 
the motion of the churn, then, though the particles 
may pass through space at a greater rate of speed, 
the motion of the particles upon each other will be 
lessened. «A maximum motion of the particles upon 
each other is obtained when the speed of the ehurn 
stops just short of setting up centrifugal force in 
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