56 CHEMICAL ACTION. 



Q. Why will WOOD BLAZE, even if it does not 

 touch tliefire? 



A. The heat of the fire drives out 

 the hydrogen gas of the wood ; which is 

 inflamed by contact with the red-hot 

 coals. 



Q. Why will a NEIGHBOUR'S HOUSE some- 

 times CATCH FIRE, though no flame of the burning 

 house ever touches it ? 



A. The heat of the burning house 

 sets at liberty ike hydrogen gas of the 

 neighbouring wood-work, which is ignited 

 by the flames or red-hot bricks of the 

 house on fire. 



Q. What is COKE ? 



A. Coal freed from its volatile gases, 

 by the action of artificial heat. 



Q. Why do ARNOTT'S STOYES sometimes 

 SMELL so strong of SULPHUR ? 



A. The fire is made of coke, which 

 contains sulphur; and, whenever the 

 draught is not rapid enough to drive the 

 sulphur up the flue, it is emitted into the 

 room. 



Q. Wliat is meant by SPONTANEOUS COM- 

 BUSTION ? 



