\ 
New York AGRICULTURAL EXPERIMENT STATION. 137 
ing for receiving the thermometer. As the milk is spread out in 
this thin layer it quickly takes up the heat from the steam 
chamber surrounding it. 
The temperature of the milk is controlled by changing either 
the valve admitting the steam or the valve regulating the milk 
flow. A slight change in either of these valves produces a quick 
response in the mercury column of the thermometer. Usually 
the milk valve was set to admit about all the milk that could be 
heated to the desired degree and the slight variations in tempera- 
ture were controlled by changing the steam valve. 
METHOD OF WORK. 
In the manipulation of the machine at the different tempera- 
tures the effort was always made to give it a fair chance to show 
what could be expected of it when handled in the average cream- 
ery at that temperature. Our ability to give it a fair trial in- 
ereased as we became familiar with the machine and its manipula- 
tion. 
The first requisite was a method of regulating the flow of milk 
and steam so that the temperature might be held constant. When 
received, the machine was provided with a float intended to con- 
trol the flow of milk automatically. After testing it in a variety 
of ways for some weeks it was condemned as too clumsy for our 
purpose and was removed. 
As finally arranged a supply tank placed sufficiently high to 
give a good fall was connected directly with the base of the 
pasteurizer and the flow regulated by a hand valve. This brought 
the milk and the steam valves near together where one man 
could reach both and still watch the thermometer. The maxi- 
mum variation, which rarely exceeded 10° C., usually occurred 
at the beginning of the process before the valves were properly 
adjusted. This having been accomplished the desired tempera- 
ture could be maintained with very little variation. 
