CARBONIC ACID 163 



genuine. But they arc dependent upon water; 

 secondary in their nature; resting upon solu- 

 bility and ionization; upon interactions be- 

 tween the two substances. So they lead us 

 to a consideration of the most intricate of 

 all mutual relations, to a purely chemical 

 study of the compounds of carbon, hydrogen, 

 and oxygen, into which water and carbonic 

 acid can be transformed. 



