THE CITY MILK PLANT 



103 



bottles are placed in baskets, which are carried on an 

 endless chain into tanks of water having different tem- 

 peratures. In this way the bottles are passed through 

 lukewarm water, then through warmer and warmer water, 

 until they reach the pasteurizing temperature. They re- 

 main at this temperature for 20 minutes or any desired 

 time; then they pass through a series of cooling tanks, 

 each successive tank containing cooler water than the 

 previous one. 



In the other type of machine, the bottles are placed 

 in trays on a large wheel revolving horizontally, where 

 they receive a heavy shower bath of water. As the wheel 

 revolves the bottles pass through water of different tem- 

 peratures just as in the above-described system, so that 

 pasteurization and cooling are accomplished by a con- 

 tinuous process. 



Mr. Bixby 1 of Boston compared pasteurization in a 

 machine with pasteurization in bottles and secured the 

 following results: 



NUMBER OF BACTERIA IN ONE CUBIC CENTIMETER 

 OF MILK. 



In both these methods of pasteurization, the same 

 degree of heat and same time of exposure were employed. 



1 Medical Record. July 15, 1911. 



