98 CHEMICAL AFFINITY. 



snow-like mass at the close of the lecture. 

 But suppose I limit the atmosphere, what 

 then? why, even the phosphorus will go out. 

 Here is a piece of camphor which will burn 

 very well in the atmosphere, and even on water 

 it will float about and burn, by reason of some 

 of its particles gaining access to the air. But 

 if I limit the quantity of air by placing a jar 

 over it, as I am now doing, you will soon find 

 the camphor will go out. Well, why does it 

 go out ? not for want of air, for there is plenty 

 of air remaining in the jar. Perhaps you will 

 be shrewd enough to say for want of oxygen. 



This therefore leads us to the inquiry as to 

 whether oxygen can do more than a certain 

 amount of work. The oxygen there (fig. 30) 

 cannot go on burning an unlimited quantity of 

 candle, for that has gone out, as you see ; and 

 its amount of chemical attraction or affinity is 

 just as strikingly limited ; it can no more be 

 fallen short of or exceeded than can the attrac- 

 tion of gravitation. You might as soon attempt 

 to destroy gravitation, or weight, or all things 

 that exist, as to destroy the exact amount of 

 force exerted by this oxygen. And when I 

 pointed out to you that 8 by weight of oxygen 

 to 1 by weight of hydrogen went to form water, 



