Principles of Milk Preservation. 115 



To use ice economically, the ice itself should be applied 

 as closely as possible to the milk to be cooled, for the 

 larger part of the chilling value of ice comes from the 

 melting of the same. To convert a pound of ice at 32 



FIG. 28. Water cooler, using either running cold water, or water and crushed 

 ice. The milk is introduced at i. m. and is spread out in m. c. in a thin cylindri- 

 cal sheet, flowing out at o. m. Cold water circulates through inside of milk 

 cylinder in w. c., while ice may be used in outer water chamber, o. w. c. 



F. into a pound of water at the same temperature re- 

 quires as much heat as would suffice to raise 142 pounds 

 of water one degree F., or one pound of water 142 F. 

 The absorptive capacity of milk for heat is not quite the 

 same as it is with water. It fluctuates with the amount 

 of solids in the milk, but for ordinary milk is about .85 

 while water is taken as a standard 1.0. Hot milk would 

 therefore require somewhat less ice to cool it than would 

 be required by an equal volume of water at same tem- 

 perature. 



In the mere melting of a pound of ice, a large part of 

 the heat in a pound of pasteurized milk will be absorbed. 

 To take advantage of this, the ice should be brought in 

 close contact with the milk rather than to spend all of 

 this absorptive capacity on cooling water which is later 

 applied to the milk. If broken ice is used directly, it 

 should be arranged so that the milk surrounds it, as in 

 this way the specific capacity for heat that is latent in 

 the ice acts on the milk instead of being radiated in part 

 to the outside. 



