FIRE. 241 



A. The fuel being decomposed (by 

 heat) into hydrogen and carbon; the 

 carbon combines with the oxygen of the 

 air, and produces combustion. 



Q. What does the combination of carbon and 

 oxygen produce ? 



A. The carbon of the fuel combining 

 with the oxygen of the air makes CAR- 

 BONIC ACID GAS. (see pp. 36, 37). 



Q. What becomes of the HYDROGEN of ilie 

 FUEL ? 



A. Hydrogen (being very inflamma- 

 ble) burns with a blaze, and is the cause 

 of the flame which is produced by 

 combustion, (seep. 34). 



Q. What becomes of the NITROGEN of the air, 

 amidst all these changes and combinations ? 



A. The nitrogen of the air escapes, 

 and is absorbed by the leaves of grass, 

 trees, and various other vegetables. 



Q. What is meant when it is said, that 



OXYGEN " SUSTAINS LIFE ?" 



A. It means this : if a person could 

 not inhale oxygen, he would die. 



Q. Wliat GOOD does this inspiration of 

 OXYGEN do ? 



Y 



