RIFRIGERATION 



63 



the difference between the temperature in the coohng tank and 

 the temperature of the refrigerator, the greater is the velocity 

 of circulation. 



4. Common Ice House. — This is the kind of ice house used 

 with the ice bunker and with the gravity-brine methods of re- 



FiG. 14. — The Cooper gravity brine system and chloride of calcium process. 



frigeration. It is not connected with the refrigerator and is 

 seldom insulated to the extent of the one used in the insulated 

 ice-house method. It is often constructed from one thickness 

 of boards; and when packing the ice, space is allowed for one 

 foot of sawdust to be packed between the ice and the wall. 

 Some ice houses are built with a double wall insulated with from 

 8 to 12 inches of shavings. If the walls are thus insulated, it 

 is advisable to have the floor also insulated; and for this pur- 

 pose no insulation is more satisfactory than cinders and cork. 



