PASTEURIZATION. 



179 



more readily than milk containing less air. If pumps are used 

 for pumping the milk, it is well to admit as little air into the 

 milk as possible. This can be accomplished by keeping plenty 

 of milk in the tank which feeds the pump, or by having a float 

 which will close the inlet to the pasteurizer as soon as the tank 

 is emptied. If the speed of the agitator in the pasteurizer 

 is great enough, the scum is forced towards the center. For 



Fig. 119. — The Jensen pasteurizer. 



some time it was thought that only the best sweet milk could 

 be pasteurized by the intermittent process of pasteurization. 

 It is well known that when a sample of milk reaches a certain 

 degree of acidity it coagulates upon heating. It was thought 

 that by the continuous method of pasteurization this would 

 interfere with getting proper results. Experiment, however, 

 shows that the coagulated sour cream and milk can be suc- 

 cessfully pasteurized, but it is still a fact that the better con- 

 dition the milk or cream is in, the easier it can be pasteurized 



