CHEMISTRY AND HEAT 



temperature at which a body changes from a liquid state to a 

 vapor or a gas is called its temperature of vaporization; and the 

 heat required to effect this change in 1 Ib. of the liquid is called 

 its latent heat of vaporization. 



When a vapor changes back to a liquid, it is said to con- 

 dense, and when a liquid changes back to a solid, it is said to 

 freeze; in either case, an amount of heat, equal to the latent 

 heat of vaporization or of fusion, as the case may be, must be 

 abstracted from, or given up, by the body. 



TEMPERATURES AND LATENT HEATS OF FUSION 

 AND OF VAPORIZATION 



The accompanying table shows the latent heats of fusion 

 and of vaporization for 1 Ib. of various substances, they having 

 first been raised to the temperature at which the change takes 

 place, and the pressure being one atmosphere, or 14.7 Ib. per 

 sq. in. The temperature of vaporization in the table is the 

 boiling point of the liquid under the ordinary atmospheric 

 pressure of 14.7 Ib. per sq. in. 



Specific Heat. The specific heat of a body is the ratio be- 

 tween the quantity of heat required to warm that body 1 

 and the quantity of heat required to warm an equal weight of 



