THE PASTEURIZATION OF MILK 



cans into a large dump vat, from which it was 

 pumped to a receiving vat upon the second floor 

 and was thence allowed to flow through a clarifier, 

 from which it was discharged into a large mixing 

 vat and thence flowed directly to the milk heater. 



FIFTH TEST. This test was made at a plant at 

 which the milk was pasteurized by means of a 

 heater somewhat similar to that shown in Fig. 3. 

 The holder was like Fig. 21. In this heater the 

 milk is forced between two water-heated cylin- 

 ders, in one of which the water was at a tempera- 

 ture of 165, and in the other of which the tem- 

 perature of the water was nearly at the boiling 

 point. The milk, while being heated, was kept in 

 agitation by means of a revolving arm, which was 

 so arranged that it moved between the two heat- 

 ing surfaces. The milk, after heating, was held 

 in a series of eight water- jacketed tanks, the water 

 surrounding the tanks being kept at a temperature 

 of from 145 to 150 F. The milk, while in this 

 holding tank, was kept in agitation by means of re- 

 volving metal stirrers. 



A sample was first taken from one of the hold- 

 ing tanks in which the milk was heated to a tem- 

 perature of 143 F. and held there for thirty 

 220 



