MECHANIC A L REPRIGBRA TlON 



137 



vaporization or "latent" heat. Thus to change water from 

 212° F. to steam at 212" F. requires a considerable 

 amount of heat which is apparently lost, hence the term 

 latent (hidden) heat. 



Fig. 59. — Showing Circulation of Ammonia in Meclianical Refrigeration. 



Ether changes into its gas at a much lower temperature 

 than water which is illustrated by its instant evaporation 

 when poured upon the hand. The heat of the hand in this 

 case is sufficient to cause vaporization and the sensation of 

 cold indicates that a certain amount of heat has been 

 abstracted from the hand in the process. 



