COOLING, STORING, AND SHIPPING MILK. 17 



cessive quantity of ice for cooling. Since the quantity of milk pro- 

 duced on a dairy farm fluctuates from season to season and from year 

 to year, it is advisable to construct a tank of two parts, the larger 

 being approximately twice the size of the smaller. With a tank of 

 that kind the larger part should be large enough to cool the quantity 

 of milk ordinarily produced. The smaller part may be used in addi- 

 tion for handling an increased supply. In case production is de- 

 creased the smaller part can be used alone, thus insuring more effi- 

 cient cooling. Such arrangements can be made with little additional 

 expense at the time of building, and they result in more efficient 

 cooling. 



As an example of what may be accomplished by such an arrange- 

 ment a test was conducted in which a 10-gallon can of milk at 91° 

 F. was placed in a concrete tank containing 1,000 pounds of water at 

 54° F. to which a 100-pound block of ice had been added. The can 

 was left in the tank from 8 a. m. until 5 p. m. on a day when the air 

 temperature ranged from 75° to 85° F. At 5 p. m. the milk had a 

 temperature of 5.3^° F. The same tank was afterwards divided into 

 two parts, one being two-thirds and the other one-third the size of 

 the original tank. Into the smaller part of the tank were placed 

 350 pounds of water at 54° F., a 100-pound block of ice, and a 10-gal- 

 lon can of milk at 90° F. The air temperature during the 9 hours, 

 from 8 a. m. to 5 p. m., ranged from 75° to 85° F., and during that 

 time the milk was cooled to 48° F., or 5-§ degrees lower than when 

 cooled in the larger tank. 



. The test was repeated with a wooden tank, a can of milk at 90° F. 

 being left for 9 hours in a tank containing 1,000 pounds of water with 

 an initial temperature of 54° F. and a 100-pound block of ice. At 

 the end of the 9 hours the milk had been cooled to 50° F. The tank 

 was then partitioned in a manner similar to the concrete tank and 

 a 10-gallon can of milk at 90° F. was placed in the smaller part, the 

 quantity of water and ice used being the same as in the concrete tank. 

 At the end of 9 hours the can of milk was cooled to 41° F., or 9 de- 

 grees lower than for a similar can in the large wooden tank. It is 

 evident that for cooling efficiency a tank holding 3 or 4 gallons of 

 water for each gallon of milk makes for more efficient use of ice than 

 a larger tank. 



LOCATION OF TANK. 



For best results the cooling tank should be covered and placed in 

 a building where it will be sheltered from the direct rays of the sun. 

 The best location, therefore, is in the milk house. When a milk- 

 cooling tank is placed outdoors, exposed to the action of the weather, 

 there is usually a rapid deterioration and a great loss in cooling effi- 

 ciency. Besides keeping milk cold a properly constructed cooling 

 tank also protects it from dust, flies, and other contaminating influ- 

 ences. 



