EGGS IN COLD STORAGE. 67 



more plain it may be considered thus: During- the 

 period when the outside air is considerably warmer 

 than the air of the storage room it is necessary to keep 

 some refrigerant at work cooling- the air within. This 

 is usually done by circulating- brine or ammonia 

 throug-h pipes, and the air of the room is circulated in 

 contact with the pipes. When the outside tem- 

 perature is hig-h, more of the refrig-erant must be 

 circulated, or its temperature must be lowered; 

 as the weather turns cooler in the fall, less re- 

 frigerant, or the same amount at a higher temper- 

 ature, must be circulated, and when the air with- 

 out reaches the temperature of the room, the 

 circulation of refrigerant must be discontinued al- 

 together. When this is done the moisture on the 

 cooling pipes begins to evaporate. This evaporation 

 added to that which is given off by the eggs them- 

 selves soon renders the air saturated with very im- 

 pure and poisonous vapors, which cause the eggs to 

 deteriorate very rapidly. 



The influence which the temperature of the refrig- influence of 



& temperature of 



erant flowing in the cooling pipes has on the condition refrigerant in 



cooling- pipes. 



of a storage room may be better understood by tak- 

 ing a specific case: A room with a temperature of 

 33 F. and a humidity of 70 per cent has a dew point 

 (temperature at which the air precipitates moisture) 

 of 25 F. Therefore any cold surface (as a pipe sur- 

 face), having a temperature of 25 F. or lower, will 

 attract moisture when exposed to the air of the room. 

 If the pipe surfaces are heavily coated with frost, as 

 they usually are as cold weather approaches, the frost 

 acts as an insulator, and the refrigerant flowing in 

 pipes must be at a considerably lower temperature 

 than the air of the room, or no moisture is attracted. 

 We have all noted how the accumulation of moisture 

 on pipe coils is slower and slower as the thickness in- 

 creases, until finally a limit is reached where no more 

 frost will form; yet owing to the largely increased 



