48 CHEMICAL ACTION. 



A. The intensity of fire-light depends 

 upon the whiteness to which the carbon 

 is reduced, by combustion. If the car- 

 bon be white hot, its combustion is 

 perfect, and the light intense ; if not, the 

 light is obscured by smoke. 



Q. Why will not CINDERS BLAZE, as well as 

 FRESH coals ? 



A. The flame of coals is made chiefly 

 by hydrogen gas. As soon as this gas 

 is consumed, the hot cinders produce 

 only an invisible gas, called carbonic acid. 



Q. Where does the hydrogen gas of afire come 

 from ? 



A. The fuel is decomposed (by com- 

 bustion) into its simple elements, carbon 

 and hydrogen gas. (see p. 33) 



Q. Why does not a FIRE BLAZE on a FROSTY 

 NIGHT, so long as it does upon another night ? 



A. The air (being very cold) rushes 

 to the fire so rapidly, that the coals burn 

 out faster, and the inflammable gas 

 is sooner consumed. 



Q. Why does a FIRE burn CLEAREST on a 

 FROST? night ? 



A. Because the volatile gases are 



