COOLING, STORING, AND SHIPPING MILK. it 
During the test with the galvanized-iron tank the air temperature 
ranged from 72° to 80° F. with an average of 76° F. At the end of 
nine hours the temperature of the water was 58° F. and the tempera- 
ture of the milk was 56.5° F. It will be noted that the minimum 
temperature of the water was reached three hours after the ice was 
added, and from that time on the temperature of the water rose slightly 
for the next two hours, until all the ice was melted. From this point 
the rise in the temperature of the water wasmorerapid. The tempera- 
GALVANIZED poke ea 
conerere mul 
aa 
CORK INSULATED 
BAM BEA ES one 2: Sone Soles 
TIME — HOURS. 
Fic. 8.—Rise in temperature of water during 9 hours in 4 types of cooling tanks. All 
tanks covered and exposed to direct rays of sun. 
ture of the milk continued to fall until just before the sixth hour, 
when the curves showed that the temperature of the milk dropped 
below the water. This was due to the fact that about one hour before 
all the ice was melted the temperature of the water began to rise 
and rose faster than the temperature of the milk dropped. This is 
caused by the fact that there is a double transfer of heat, first from the 
air to the water, then from the water to the milk. 
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