90 CHEMICAL AFFINITY. 



the particles of which it consists chemically. 

 Now we have never yet been able to reduce 

 either oxygen or hydrogen to the liquid state ; 

 and yet their first impulse when chemically 

 combined is to take up first this liquid condition 

 and then the solid condition. We never com- 

 bine these different particles together without 

 producing water ; and it is curious to think how 

 often you must have made the experiment of 

 combining oxygen and hydrogen to form water 

 without knowing it. Take a candle, for in- 

 stance, and a clean silver spoon (or a piece of 

 clean tin will do), and if you hold it over the 

 flame you immediately cover it with dew not 



Fig. 30. 



a smoke which presently evaporates. This 

 perhaps will serve to show it better. Mr. An- 



