THE PASTEURIZATION OF MILK 



the same apparatus was in use. No apparent rea- 

 son could be seen for the variation. Milk at this 

 plant, as received from the patrons, was allowed 

 to flow from the weigh vat into the mixing vat, 

 from which it was pumped to a vat upon the sec- 

 ond floor, thence it flowed into a clarifier, from 

 which it was discharged into a large mixing vat on 

 the same floor. It then flowed by gravity to the 

 pasteurizing vats on the first floor. 



FOURTH TEST. A further test was made at an- 

 other pasteurizing plant, in which the milk was pas- 

 teurized by means of a heater and holder, shown 

 in Figs. 5 and 22. In this heater the milk was 

 forced between two concentric cylinders, in each 

 of which hot water was contained, having a tem- 

 perature of 159. The milk while being heated 

 was kept in agitation by the rapid revolution of 

 one of the cylinders above referred to. After 

 heating, the milk flowed by gravity into a series of 

 insulated tanks, in each of which it was held for 

 twenty-four minutes. On account of the fact, how- 

 ever, that milk as discharged from the heater 

 flowed first into a tank from which the various 

 holding tanks were filled, and on account of the 

 added fact that when these tanks were discharging 

 218 



