28 BULLETIN 744, U. S. DEPARTMENT OF AGRICULTURE. 
The milk was 224 hours in transit and the average air temperature 
of the baggage car was about 73° F. The temperature of the milk 
in the different cans was between 44° and 45° F. when placed in the 
car. This test demonstrates that the temperature of milk upon 
its arrival at destination is no indication of the temperatures which 
it has experienced in transit and that jacketed and insulated cans 
prevent rapid fluctuations in temperature. 7 
When milk is cooled to between 40° and 45° F. on the farm, it may, 
through the use of felt jackets or insulated cans, reach the market 
with but a comparatively few degrees rise in temperature even in 
very hot weather. The use of felt jackets or insulated cans adds 
somewhat to the cost of shipping milk, because of the initial cost of 
the jackets or insulated cans and the increased transportation charges 
due to the greater weight. Taking all these things into considera- 
tion, however, it is believed that in many cases it is more economical ” 
for the dairyman to use some form of protection in shipping his milk 
to the city. 
SUMMARY. 
Milk must be kept at a low temperature (50° F. or below) from 
the time it is produced until it is consumed if its quality is to be 
maintained. 
Prompt cooling of milk on the farm necessitates the most efficient 
use of water in both surface coolers and cooling tanks. 
Tce is needed if milk is to be cooled quickly to low temperatures. 
Cooling tanks should be covered, protected from the sun, insulated, 
and of such size as to use ice efficiently. 
Felt jackets or insulated cans proved to be very effective in keep- 
ing milk cold during long shipments in hot weather and in prevent- 
ing freezing during cold weather. 
ADDITIONAL COPIES 
OF THIS PUBLICATION MAY BE PROCURED FROM 
THE SUPERINTENDENT OF DOCUMENTS 
GOVERNMENT PRINTING OFFICE 
WASHINGTON, D. C. 
AT 
10 CENTS PER COPY 
V 
