HOW MAY WE KEEP FOODS FROM SPOILING? 343 



at one side to the bottom part of the refrigerator, where 



warm food substances give off their heat to the cold air, 



which is warmed and gradually rises, passing in again at 



the top of the ice chamber. Thus we have a circulation 



of air within the 



refrigerator. The 



warm air returns 



to the ice which 



absorbs heat in 



the process of 



melting and the 



heat is carried off 



in the water which 



drips into the 



drain pipe. 



Electric and 

 Other Methods 

 of Refrigeration. 

 The application of 

 the cold-storage 

 plant to the home 

 is found in the 

 newer types of re- 

 frigerators which 

 run by electricity 

 or by gas. These automatic refrigerators are more expen- 

 sive in the first cost than ordinary ice boxes, but they have 

 the advantage- of being able to keep a nearly constant 

 temperature all the time and they are economical to run. 

 Since these automatic devices are colder than the ordinary 

 refrigerators using ice, the arrangement of foods in them 

 is of less importance. 



A New Development in Refrigeration. One of the latest 

 developments in refrigeration is the use of "dry ice," 

 which is solid carbon dioxide. This has the advantage of 



Are the foods properly placed in this electric re- 

 frigerator ? Explain how the cold air circulates. 



