12 



BULLETIN 744, U. S. DEPARTMENT OP AGRICULTURE. 



Ill 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 



"5 3 



IOQOAM 



-4 — ^? r 7 



T/ME- HOURS. 



« W 



Fig. 9. 



-Rise in temperature of water during 9 hours in 4 types of cooling tanks, 

 tanks uncovered and in milk house. 



All 



milk was 49.5° F. Notwithstanding the fact that the average air 

 temperature was 5^ 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 5£ 

 degrees lower than in the concrete tank and 8£ 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. 



