EFFECTS OF EVAPORATION 7 



What must be done to the liquid sulphur dioxide in order to 

 cool the ice box? 



What must be done to the gas in the refrigerating coils before 

 it can be used again? 



Iceless Coolers. The principle of evaporation, used in keeping 

 food and water cool by the natives of tropical countries, is used to-day 



FIG. 6. 



n&f. 



by people of every country by making a container of porous material 

 which is dipped in water for a few moments every day or two. 

 The water evaporates from the material if the container is placed 

 where there is a good circulation of air, maintaining a low degree 

 of temperature, even as low as some of the average ice boxes. Fig. 7. 

 Inexpensive Iceless Refrigerators. In some parts of the country 

 refrigerators are made by covering a frame of wood with burlap, 



