10 INTRODUCTION. 



bustion. This combination may be 

 observed by any one, on applying a 

 lamp-glass, or chimney, over a burning 

 lamp. The hydrogen of the flame 

 (one of the components of oil being 

 hydrogen) will unite with the oxygen 

 of the air, and will be condensed, in 

 the form of vapor, on the inside of the 

 glass. This process is continually going 

 on during the burning of any substance 

 containing hydrogen ; although, in the 

 above process, the vapor will be visible 

 only so long as the glass is sufficiently 

 cool to condense it, as it is formed. 



Oxygen occupies the most important 

 place in nature. No organized being 

 could exist without it ; and yet, nothing 

 is more destructive to life. No fire 

 could burn without it ; and yet, to this 

 very property of its being a supporter 



