84 



LECTURE IV. 



CHEMICAL AFFINITY HEAT. 



WE shall have to pay a little more attention to 

 the forces existing in water before we can have 

 a clear idea on the subject. Besides the at- 

 traction which there is between its particles to 

 make it hold together as a liquid or a solid, 

 there is also another force, different from the 

 former ; one which, yesterday, by means of 

 the voltaic battery, we overcame, drawing from 

 the water two different substances, which, when 

 heated by means of the electric spark, attracted 

 each other, and rushed into combination to 

 reproduce water. Now I propose to-day to 

 continue this subject, and trace the various 

 phenomena of chemical affinity ; and for this 

 purpose, as we yesterday ^ considered the cha- 

 racter of oxygen, of which I have here two jars 

 (oxygen being those particles derived from the 



