90 SCIENCE OF THRESHING. 



heat or B. T. U. to change a pound of ice to water at 



32 degrees. It is found that it takes a quantity of heat 

 expressed by about 966 B. T. U. to change one pound 

 of water into steam, and this, therefore, is 966 times 

 as much heat as is required to raies a pound of water 

 from 62 to 63 degrees. Thus the latent heat o fsteam 

 or amount of energy which is transmitted to steam at 

 a temperature of 212 degrees is about 966 B. T. U. 

 At different temperatures, the latent heat of steam 

 differs. The heat which is taken into the water when 

 it changes from water to steam is given off again 

 when it condenses or turns back to water. 



