THE PASTEURIZATION OF MILK 



in adjustment, and careful handling is necessary. 

 Either form will control the milk temperature 

 within 2, as indicated by the temperature re- 

 corder. 



A method of temperature control which was 

 proposed by the writer some years ago had for its 

 basis a principle which has been made use of 

 in this connection to a limited extent only. This 

 consisted in this, namely, that the temperature of 

 the heating medium be so controlled as to remain 

 constant, and that the milk which flowed out of 

 the heater be kept at a uniform temperature by 

 varying the speed of flow of the milk through 

 the heater. This reverses or inverts the present 

 practice, in which the speed of milk flow is con- 

 stant, while the temperature of the heating med- 

 ium varies. The proposed method would have 

 this advantage, that no part of the milk could ever 

 be heated higher than the temperature of the water, 

 and if this water temperature were controlled by 

 a thermostat no scorching of the milk would ever 

 result. It is evident that with a uniform heating 

 medium the milk which flows through the heater 

 will take up more of this heat if the speed of flow 

 is slow than it will if the milk moves rapidly over 

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