154 



ELEMENTARY GENERAL SCIENCE 



CHAP. 



can be defined as the number of heat' units required to 

 change the unit mass of water into steam without changing 

 its temperature. 



The latent heat of water can be measured by mixing a known 

 quantity of ice with a known quantity of warm water and 

 ascertaining the amount of heat given up by the warm water to 

 melt the ice. In a similar manner, by mixing a known quantity 

 of steam with a known amount of water and ascertaining how 



FIG. 70. Arrangement for passing steam into a vessel containing cold water. 



much heat the steam gives to the water, we can measure the 

 latent heat of steam. 



EXPT. 154. Put some ice into a known weight of hot water. 

 Notice the temperature when the ice is melted. Determine 

 the weight of the ice by reweighing the water. Notice that a 

 small quantity of ice requires a large quantity of heat to 

 melt it. 



EXPT. 155. Pass steam, produced by heating water in a 

 flask, through a delivery tube into cold water. Notice the 

 rapid rise in temperature of the water, and determine the 

 weight of water condensed. To prevent hot water from coming 



