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PURE FOOD IN THE HOME 



blanket. If you desire to keep 

 the ice, and not the food, then 

 this is the way to do it. 



The iceless refrigerator. An 

 interesting home project is the 

 making of an iceless refrigerator. 

 Directions may be found in the 

 U. S. Dept. of Agriculture pam- 

 phlet, Food Thrift Series, No. 4. 

 The principle of evaporation and 

 transfer of heat from the inside 

 to the outside of the box explains 

 its value. Study the diagram 

 and see how it might be usefully 

 applied to your own home. 



Thermos bottle. The ther- 

 mos bottle, as a study of the 

 diagram will show, is another applica- 

 tion of insulation. It is essentially a 

 double walled bottle or one bottle in- 

 side of another, with a vacuum space 

 between. A vacuum is a better insu- 

 lator than air. The inside walls of 

 the bottles surrounding the vacuum 

 are mirrors. They reflect radiant heat 

 energy and prevent its passage across 

 the vacuum. Thus the thermos bot- 

 tle keeps cold substances cold, and hot 

 substances hot, by means of insulation. 

 Canning foods. Canning is simply 

 a method by which foods are boiled to kill the bacteria in 

 them and then placed in vessels into which no more bacteria 



The iceless refrigerator. The out- 

 side canvas dips into a pan of 

 water at the top and drains into 

 another pan at the bottom of the 

 refrigerator. (U. S. Dept. Agri.) 



