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EXPLANATION OF EXERCISE VII 



There are several kinds of conical coolers on the market, which are 

 suitable for use on farms. These coolers furnish an efficient piece 

 of apparatus at a reasonable price. Their use has often been abused 

 since they are frequently stationed and used in places where they are 

 exposed to dust and dirt, and in order to minimize the danger from 

 such contamination, some coolers are provided with a hood which 

 surrounds that part of the cooler over which the milk flows. The 

 refrigerating material most commonly used in these coolers is ice and 

 water, although they may be attached to a brine barrel or a running 

 water supply, if such a supply is available. Whatever the refrigerating 

 substance used in these coolers, it should be stirred frequently. If it 

 is not stirred, the refrigerating material next to the walls soon becomes 

 warmed by the milk passing over the cooler and so loses its efficiency. 

 The purpose of the following experiment is to compare the effi- 

 ciency of a conical type of cooler when the refrigerating material 

 inside the cooler is stirred and when it is not stirred. 



EXERCISE VII 

 COOLING MILK WITH A CONICAL COOLER 



1 . Weigh a can of whole milk and heat it to 95 F. The purpose 

 of heating the milk is to bring it to nearly the same temperature as 

 when drawn from the cow. Place forty pounds of ice inside the cooler 

 and fill the cooler to the overflow pipe with cold water. Run the 

 milk over the cooler and note the time it takes the first milk which 

 comes from the receiving tank to reach the outlet spout of the cooler. 

 Do not stir the water inside the cooler. Record the temperature of 

 the milk at the outlet spout every three minutes. Note the time 

 required to pass the milk over the cooler. After all of the milk has 

 passed over the cooler, stir it thoroughly and record the final tempera- 

 ture. Take the temperature of the water near the walls of the cooler. 

 Stir the water and then take its temperature. Weigh the amount of 

 ice left. 



2 . Repeat the experiment, heating the milk to the same tempera- 

 ture and using the same amount of ice, but in this case stir the ice 

 water in the cooler continuously. Record the temperature of the 

 milk every three minutes. Stir the can of milk and take the final 

 temperature. Weigh the amount of ice left. Compare the results 

 obtained by the two methods of cooling. Make a drawing of the 

 cooler. Compute the capacity of the cooler per hour. 



State in your notes the name of the cooler used. 



