COOLING HOT-BOTTLED PASTEURIZED MILK. 5 
The corrected anemometer readings were in every case higher by 
approximately 10 per cent than those obtained with the Pitot tube. 
The wet-bulb and the dry-bulb temperatures were taken by a sling 
psychrometer. The barometer was read during each test, and the 
weight of air per cubic foot determined from the barometer and the 
wet-bulb and the dry-bulb readings. 
Readings of air velocities were also taken with an anemometer over 
the tops of the crates. These readings, taken at different places over 
the stacks, were practically the same and averaged 182 feet a minute 
over the quart crates and 156 over the pints. It is very important 
that a practically uniform velocity of air be maintained throughout 
the stack in order to cool all bottles at the same rate. Thirty crates, 
stacked 5 high, were used in all experiments, 15 for quart bottles and 
15 for pints. Reading of volts, amperes, and speed of motor were 
also taken during each experiment. 
RELATIVE RATE OF COOLING OF MILK AND WATER. 
As the average specific heat of whole milk is less than that of water, 
it may be expected to cool faster under the same conditions. This, 
however, is not the case when the cooling is done in bulk, such as when 
in bottles or cans, as is plainly shown hi figure 2. These curves are 
plotted from temperature readings taken in a quart bottle of milk 
and a quart bottle of water, subjected to the same conditions of air 
velocity, air temperature, location of thermometers in bottles, etc. 
It will be seen that the curve representing the rate of cooling the 
milk is of a uniformly higher temperature than the similar curve for 
water. 
On account of the small variation in the relative rate of the cooling 
of milk and water it was considered advisable to use water in these 
experiments, as it was more easily obtained and handled. Bottles 
of milk, however, were distributed throughout the crates, in selected 
places, and in these bottles, as well as in those containing water, simi- 
larly placed, the temperature readings were taken. 
RELATIVE RATE OF COOLING WITH STILL AIR AND FORCED AIR. 
In order to obtain data to compare the rate of cooling bottles and 
cans containing milk when exposed to still air and to moving air, pint 
and quart bottles, and 10-gallon cans of milk were placed in a refrig- 
erated room, the constant temperature of which was held at approxi- 
mately 40° F. (4.4° C). The initial temperature of the milk was 
about the same in all instances. The results are seen in figures 3, 4, 
and 5. Figures 3 and 4 show the relative drop in temperature between 
pints and quarts, respectively, when exposed to still air and to mov- 
ing air, and figure 5 shows similar results for the 10-gallon cans. 
