FRUIT STORAGE 



95 



Fig. 81. PRESSED CORK 



waste cotton, mineral wool, and even shavings or saw- 

 dust have been used with -good results. 



Insulating Materials. The construction of a modern 

 storage house calls for 

 great care and attention 

 to details of the work. 

 Carelessness or the use of 

 poor material will often 

 result in the inability of 

 the operators to control 

 the temperature of the 

 house. All of the differ- 

 ent materials used in con- 

 struction have different 

 insulating values. The de- 

 gree with which they will 

 prevent the passage of 

 heat or cold is different 

 with each material used. 

 For determining the insu- 

 lating value of the dif- 

 ferent materials, certain 

 units in measuring heat 

 have been established. 

 One used in England, 

 and to a considerable ex- 

 tent in the United States, 

 is commonly known as the 

 British Thermal Unit, or, as it is usually written, 

 B. T. U. It means the amount of heat required 

 to raise the temperature of one pound of water 

 one degree Fahrenheit. The French and German 



Fig. 82. MINERAL WOOL 



Fig. 83. FIBER-FELT 



