BOILERS. 199 



radiates heat very slowly, and therefore 

 keeps the water hot. 



Q. Why does a SAUCEPAN which has been USED, 

 boil QUICKER than a NEW ONE ? 



A. Because the bottom and back are 

 covered with soot; and the black soot 

 rapidly absorbs the heat of the glowing 

 coals. 



Q,. Why should the FRONT and LID of a 

 SAUCEPAN be clean and BRIGHT ? 



A. As they do not come in contact 

 with the fire, they cannot absorb heat ; 

 and (being bright) they will not suffer 

 the heat to escape by radiation. 



Q. In what state should a SAUCEPAN be, in 

 order that it may BOIL QUICKLY ? 



A. All those parts which come in 

 contact with the fire should be covered 

 with soot, to absorb heat ; but all the rest 

 of the saucepan should be as bright as 

 possible, to prevent the escape of heat by 

 radiation. 



Q. Why is it said that " SATURDAY'S KETTLE 



BOILS the FASTEST ?" 



A. Because on Saturday the front 

 and top of the kettle are generally cleaned 



