28 BULLETIN 744, U. S. DEPARTMENT OF AGRICULTURE. 



The milk was 22^ 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. 



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. 



Ice 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. 



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