10 BULLETIN 744, U. S. DEPARTMENT OF AGRICULTURE. 
cents a hundredweight, would be $72. Frequently ice costs more than 
the price named, which would add to the saving effected by an in- 
sulated tank. While few dairymen would waste so large a quantity 
of ice, the result indicates the economy of using a covered, insulated 
tank. 
Four other tests were conducted with the same tanks under best 
service conditions. All tanks were covered and sheltered. The gal- 
vanized-iron, concrete, and wooden tanks each contained 1,000 pounds 
§ 
TEMPERATURE, PEGREES F 
x) 
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— 
Gs 5a 2 3 4 a 6 r) 10 
SAS, 10:0 OAS. 12:00NV00NV 2:00 FA. 4-00 PH. 
TUVIE—- HOURS. 
Fic. 7—Rise in temperature of water during 9 hours in 4 types of cooling tanks. 
P 
All tanks uncovered and exposed to direct rays of su 
of water at 54° F., a 100-pound block of ice, and a 10-gallon can of 
- warm milk; the cork-insulated tank contained the same quantity of 
water and ice and two 10-gallons cans of milk. In each case the block 
of ice was placed close to the can in order that the milk might receive 
its immediate cooling effect. The water in the tank was slightly 
stirred each hour, after which the temperature reading was taken. 
The milk was not stirred during any of the tests; the results of the 
tests are shown in figure 11. 
