120 



Common Science 



Hot 



Hot 



Cold the absence of 

 heat. Cold is merely the 

 absence of heat; so if 

 you keep the heat from 

 escaping from anything 

 warm, it cannot become 

 cold ; while if you keep 

 the heat from reaching a 

 cold thing it cannot be- 

 come warm. A blanket 

 is just as good for keep- 

 ing ice from melting, by 

 shutting the heat out, as 

 it is for keeping you 

 warm, by holding heat in. 



Explain why ice 

 is packed in straw 

 or sawdust; why 

 a sweater keeps 

 you warm. 



Select from 



Gas 



i rlame 



FIG. 59. 



the following 

 list the good 



What makes Conductors of 



heat from the 

 poor conductors (insulators) : glass, silver, iron, wood, straw, 

 excelsior, copper, asbestos, steel, nickel, cloth, leather. 



Diagram of a hot-water heater, 

 the water circulate? 



Inference Exercise 

 Explain the following : 



171. If the axle of a wheel is not greased, it swells until it sticks 

 fast in the hub ; this is a hot box. 



