WARMING ROOMS. 237 



Q. What BECOMES of the steam, after it has 

 been condensed ? 



A. It is dissolved by the air, and 

 forms a part of its invisible vapour. 



Q. Is AIR a good CONDUCTOR ? 



A. No ; air is a very bad conductor, 

 and is heated (like water) by convection. 



Q. How is a ROOM WARMED by a STOVE? 



A. The air nearest the fire is made 

 hot first; the cold air descends, is 

 heated also, and rises in turn ; and this 

 goes on, till all the air of the room is 

 warmed. 



Q. Why are FIRES placed on the FLOOR of a 

 room, and not towards the CEILING? 



A. As heated air always ascends, if 

 the fire were not near the floor, the 

 lower part of the air (which we want to 

 be the warmest) would never be bene- 

 fited by the fire at all. 



Q. If you take a POKER out of the fire, and 

 hold the HOT END DOWNWARDS, why is the HANDLE 

 so intensely HOT ? 



A. Because the hot end of the 

 poker heats the air around it, and this 

 hot air (in its ascent) scorches the poker, 

 and the hand which holds it. 



