52 CHEMICAL ACTION. 



Q. Why is not the red hot wick kindled ly 

 the air AROUND it, without BLOWING it ? 



A. Because oxygen is not supplied 

 with sufficient freedom, unless it be blown 

 to the wick. 



Q. When is this experiment most likely to 

 succeed ? 



A. In frosty weather ; because the 

 air contains more oxygen then, being 

 condensed by the cold. 



Q. Why does a POKER, LAID ACROSS a dull 

 FIRE, revive it ? 



A. For two reasons. 1st Because 

 the poker concentrates the heat, and 

 therefore increases it : and 



2ndly Because the poker arrests the 

 air which passes over the fire, and pro- 

 duces a draught. 



Q. Why do SEVERAL PIECES of WOOD or 

 coal burn BETTER than ONE ? 



A. When there are two or three 

 pieces of wood on a fire, the air (circu- 

 lating round them) produces an eddy or 

 draught, which draws up the fire. 



Q. Why are STOVES fixed on the FLOOR of 

 a room ? 



