114 Milk and Its Products. 



for revolving the bowl. (The more common types of 

 separator l)owls are shown in Figs. 10-13.) Usually 

 the bowl is driven in an upright position, but there 

 are separators in which the bowl is driven in a hori- 

 zontal position, and in the greater number of ma- 

 chines the walls of the bowl are cylindrical. In the 

 process of separation the milk flows into the bowl, 

 and, partaking of the centrifugal force, is forced to 

 the extreme outer edge of the bowl. As the milk 

 continues to flow in, the bowl begins to fill from 

 the outside toward the center. The centrifugal force 

 acting more strongly upon those parts of the milk 

 which have the greatest specific gravity, they are 

 thrown to the extreme outside, and the lighter por- 

 tions, the fat globules, with whatever may adhere 

 to them, are forced to the center. Attached to the 

 extreme outer edge of the bowl are one or more 

 tubes, which, bending inward along the side of the 

 bowl, find an opening near the center. These are 

 the outlets for the skimmed milk. From the ex- 

 treme center of the bowl, also leading to the out- 

 side, is the cream outlet. When the bowl becomes 

 filled with milk, the centrifugal pressure will force 

 out through the skimmed milk outlets the milk nearest 

 the outside of the bowl. These outlets are made 

 of such size in comparison with the size of the bowl, 

 the speed of the machine, and the size of the inflow 

 tube, that they have a capacity of discharging the 

 milk from .4 to .9 as fast as it runs in ; the remain- 

 ing contents of the bowl are then forced toward 

 the center, and find an exit through the cream 



