THE PASTEURIZATION OF MILK 



tank upon the receiving floor. From this tank it 

 flowed by gravity to the pasteurizers on the floor 

 below. 



SIXTH TEST. This test was made at a plant in 

 which the milk was heated by means of an appa- 

 ratus shown in Fig. 11, where the milk is heated 

 by means of what is known as a Multitube Heater. 

 In this form of heater a series of large tubes are 

 so arranged that several smaller tubes extend 

 through them. The milk is forced through the 

 inner tubes, while hot water is forced through the 

 large surrounding tubes. After heating, the milk 

 is discharged into a series of eight holding tanks 

 similar to those described in test No. 5. The water 

 which is used to heat the milk in this apparatus is 

 itself heated in a tank outside of the milk heater 

 and is kept at a temperature varying between 144 

 and 163, the temperature rarely exceeding 154. 

 From this tank the water is pumped to the milk- 

 heating apparatus. 



The conditions at this plant were apparently fa- 

 vorable for securing good results. The fact that 

 the temperature of the heating water was carefully 

 controlled, made it impossible to superheat or 

 scorch any of the milk. The first sample of milk 



222 



