SEPARATION OF CREAM. 



135 



it immediately begins to separate into three distinct layers. 

 The centrifugal force acting in a horizontal direction forces 

 the heaviest portions of the milk and the precipitated albu- 

 minoids, ash, filth, and a multitude of germs over next to 



Fig. 73. — ^The Reid separator. 



Fig. 74. — The Sharpies separator. 



the wall of the separator bowl, and into a solid and more or 

 less gelatinous layer, which is known as the " separator slime." 

 In very impure milk this substance is so plentiful that it is 

 likely to clog the separator in a very short time, and before 

 much separation is accomplished it is necessary to clean out 

 the bowl. The second layer is the skim-milk, while the cream, 

 being the lightest, is forced to the center of the bowl and forms 

 the third portion mentioned. There is no distinct line of 

 demarcation between the layers of skimmed milk and cream. 

 They overlap each other and form a sort of zone, rather than 

 a sharp separation. The richest cream is nearest the center 

 of the bowl, and gets thinner toward the outer portion of the 

 bowl; consequently, by turning the outlet for the cream, or 

 cream-screw, nearer the center of the bowl, the cream is increased 



