12 BULLETIN 744, U. S. DEPARTMENT. OF AGRICULTURE. 
In the case of the concrete tank the air temperature ranged from 
72° to 85° F. with an average of 79.4° F. or 3.4 degrees higher than in 
the case of the galvanized-iron tank. Notwithstanding this fact the 
final temperatures of the water and milk were 3 degrees lower in the 
concrete tank. 
In the test of the wooden tank the air temperature ranged from 79° 
to 85° F. with an average of 81.1° F. for the 9-hour period. At the 
end of the test the tank-water had a temperature of 50.5° F. and the 
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VIMIE- HOURS. 
Fic. 9.—Rise in temperature of water during 9 hours in 4 types of cooling tanks. All 
tanks uncovered and in milk house. 
milk was 49.5° F. Notwithstanding the fact that the average air 
temperature was 54 degrees higher than in the case of the galvanized- 
iron tank and 1.7 degrees higher than in the case of the concrete tank, 
the temperatures of the water and milk at the end of the test were 55 
degrees lower than in the concrete tank and 84 degrees lower than in 
the galvanized-iron tank. This again illustrates the superiority, from 
the milk-cooling standpoint, of a wooden tank over either concrete or 
galvanized iron. 
