TRANSFER OF HEAT 79 



8. What is meant by latent heat ? What work is done by this 

 heat? Since the temperature of ice is 32 F., and ice melts at 

 32 F., why does a block of ice in an ice house remain solid 

 through the summer ? Why does not ice on a pond melt at once 

 when the sun strikes it ? Why does a snowstorm often end in 

 a storm of rain ? 



SECTION III 

 TRANSFER OF HEAT 



89. Methods of Transfer. We know that water 

 standing in a room becomes the same in temperature as 

 the air around it ; that if a warm body be placed near 

 a colder one, it loses some of its heat, while the other 

 becomes warmer; that the earth is warmed from the 

 sun ; and that a room may be warmed from a stove or 

 radiator, or a whole house even may be heated from a 

 furnace in the cellar. These things show that heat 

 must be able to travel from one place to another. Heat 

 may be transferred (carried from place to place) in three 

 different ways, by conduction, radiation, and convection. 



90. Conduction. Conduction is the transfer of heat 

 from one particle to another which touches it, without 

 change of relative position of the particles. Heat may 

 flow from place to place in the same mass, or from one 

 body to another which touches it, by conduction. Each 

 vibrating molecule is supposed to increase the energy 

 of vibration of those which it touches; they in turn 

 give greater energy to those that they touch ; and so on. 

 But each molecule remains in its place ; though it may 

 vibrate faster, its position among the others is not 

 changed. 



