44 CHEMICAL ACTION. 



2ndly The heat of the fire is per- 

 petually drawn off, by the conversion of 

 water into steam. 



Q. Why does DRY wood burn BETTER than 



GREEN ? 



A. 1st Because no heat is carried 

 away, by the conversion of water into 

 steam : and 



2ndly The pores of dry wood arc 

 filled with air, which supply the fire with 

 oxygen. 



Q. Why do TWO pieces of WOOD burn 



BETTER than ONE ? 



A. 1st Because they help to en- 

 tangle the heat of the passing smoke, and 

 throw it on the fuel : and 



2ndly They help to entangle the air 

 that passes over the fire, and create a 

 kind of eddy or draught. 



Q. Why does SALT CRACKLE when thrown 

 into a FIRE ? 



A. Salt contains water; and the 

 cracking of the salt is owing to the sudden 

 conversion of the water into steam. 



Q. Wliy will not wood or paper burn, if they 

 are steeped in a solution of POTASH, jfaosphate of 

 LIME, or AMMONIA fhartshorn) ? 



