26 FIRST LESSONS IN DAIRYING 



forming two walls or layers, one within the other. 

 If outlets of proper size have been made, one open- 

 ing into the vertical wall of skim milk, the other 

 into the wall of cream, and a continuous supply of 

 milk is delivered into the bowl near the bottom, it 

 will push that which is already in out through the 

 respective openings. Thus we have milk entering 

 the bowl and cream and skim milk separating into 

 distinct layers as they pass up through the bowl 

 and escaping through the respective outlets. This 

 is the principle on which all separators are based, 

 although some may introduce the milk from the 

 bottom, others from the top, while some take the 

 skim milk or cream or both from the top, others 

 from the bottom. 



The introduction of internal devices either in- 

 creases the amount of time required for the milk 

 to pass through the bowl, or else divides it into thin 

 layers, which permit the cream to more quickly 

 find its way into the current moving toward the 

 center of the bowl, unobstructed by the current of 

 skim milk moving away from the center. Most of 

 the clean skimming machines approach more or 

 less closely this latter arrangement. 



Getting milk in motion. Most bowls have some 

 interior arrangement which assists the milk in 

 taking the motion of the bowl, otherwise the milk 

 would revolve more slowly than the bowl. 



Efficiency. The thoroughness of mechanical sep- 

 aration depends on the force generated, the rate of 

 inflow, the temperature of the milk, condition of the 

 milk, and the smooth running of the machine. The 



