348 THE APPLE 



A much smaller amount of surface is required to do a certain re- 

 frigerating duty when the pipes are clean than when the frost has 

 been allowed to accumulate, and the economy of a device that will 

 keep the refrigerating pipes free from frost at all times will be 

 appreciated by any person familiar with the business, for it is well 

 known that frosted pipes are partially insulated, the degree of 

 insulation depending on the thickness of the coat of frost. The 

 Cooper chloride of calcium process consists simply in placing a 

 quantity of chloride of calcium so that the brine resulting from a 

 union of the moisture in the air of the storage room with the salt 

 will drip over the refrigerating pipes. After passing down over 

 the pipes the brine falls into a water-tight floor, which is provided 

 with drip connections to the sewer. This effectually and continually 

 disposes of the brine, which contains the moisture and impurities 

 from the air of the storage room, therefore making contamination 

 from this source impossible. 



The indirect circulation system. The auxiliary method of cool- 

 ing, known as the indirect circulation system, consists of a space 

 for the circulation of air between the inner and outer insulation 

 of the cold-storage building. It has been demonstrated that this 

 space need not be more than one inch in thickness to accomplish 

 the desired result. The air is drawn from near the floor of the 

 ice house by a fan and forced through the space provided for 

 it. After accomplishing its work by absorbing the heat which 

 penetrates from the outside, it is returned to the ice house, where 

 it is let in near the ceiling. The circulation not only covers the 

 outside walls of the building but the ceiling as well. The air of 

 the indirect circulation system does not enter the rooms ; it merely 

 circulates around them in a thin sheet between the interior and 

 exterior walls of the building. The penetration of outside heat 

 during the summer is effectually prevented, and even in ex- 

 tremes of hot weather no variation of temperature is noticeable 

 in the rooms. 



Ventilation of cold-storage rooms. Though most of the impuri- 

 ties natural to the air of cold-storage rooms are disposed of by being 

 frozen onto the pipes, there are certain gases for which moisture 

 has little or no attraction, and these will remain in circulation if 

 not displaced by forcing in fresh air. 



