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LABORATORY MANUAL 
SERIES D. 
Hand Separators. 
Materials necessary for 10 students: 
2 —Hand separators. 
6 — Pails. 
60-80—Pounds of milk for each of last 5 exercises. 
EXERCISE NO. 7 
Object: To become acquainted with the principle and construction of a cream 
separator. 
Procedure: The principle upon which the centrifugal cream separator is 
based is the fact that the fat of milk has a specific gravity of 
approximately .90 and is found in the serum (sp. gr. 1.04) as 
an emulsion. As centrifugal force is applied to the milk in a 
separator bowl, the milk is divided into three parts: namely, 
the heavier part, composed of the heaviest portions of the 
milk, albuminoids, ash, sediment, germs, etc., and is commonly 
known as “slime;” the second layer, or next heaviest part is 
the skimmilk, and likewise makes its way to the outside of 
the bowl as a result of centrifugal force. The lightest part 
or cream is crowded to the center of the bowl by the heavier 
skim milk. There is no clear line of demarcation between the 
skimmilk and cream, since separation is continually taking 
place, but the richest cream is always found nearest the center 
of the bowl. The skimmilk nearest the outside of the bowl 
contains the least fat and therefore the separator bowls are 
so constructed that the skimmilk is carried off from the out¬ 
side layer. 
A. Become familiar with each of the separators provided, by as¬ 
sembling, operating, handling, etc. Free use should be made 
of the instruction books. 
