CHAPTER III 

 REFRIGERATION AND ITS USES 



I. THE REFRIGERATOR 



181. Use of the Refrigerator. The refrigerator is probably 

 found in as many modern houses as is the furnace. It is 

 probably also true that the health and comfort of the family 

 depend upon the use of the refrigerator during the summer 

 months in as large a measure as they do upon modern methods 

 of heating furnace, steam, or hot water heating during 

 the winter months. Owing to the difficulty of securing ice, 

 the cellar must still be used in many rural districts as a sub- 

 stitute for the refrigerator, just as the stove is used in the 

 place of the more modern and adequate heating devices. 

 In most town and city houses, the refrigerator is now considered 

 a necessity. 



182. Principle of the Refrigerator. Most decay is the 

 result of the action of MICROORGANISMS upon vegetable or 

 animal matter. Microorganisms are minute plants or animals 

 so small as to be seen only by means of powerful microscopes. 

 Fermentation, or the action of microorganisms, is hastened by 

 moderately high temperature and plenty of moisture. Lower- 

 ing the temperature of foods, or lessening the moisture in the 

 foods delays decay. The function of the refrigerator is to 

 ward off or delay decay as far as possible. It does this by 

 providing a stream of cool, very dry air in which the foods are 

 placed. The effectiveness of the refrigerator depends largely 

 upon the circulation of the air within it. The stronger the 

 circulation, the more effective the refrigerator in preventing 

 decay (see Chap. VIII, Microorganisms). 



183. Construction of the Refrigerator. The refrigerator is 

 practically a box, the walls of which are usually made of 



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