CARBONIC ACID 148 



* + 

 hydrogen by (H) and of ionized hydroxyl by 



(OH) : - 



If (H) = 0.0000001 N = (OH) 



the solution is neutral; 



if (H) > 0.0000001 N > (OH) 



the solution is acid; 



if (H) < 0.0000001N < (OH) 



the solution is alkaline. 



It remains to point out that implicit in 

 these definitions is the well-founded hypothesis 

 that in water the concentrations of hydrogen 

 and hydroxyl ions vary inversely, so that 

 with constant temperature under all circum- 

 stances their product is constant : ! — 



(H) X (OH) = K 



Substituting in this equation the value 

 0.0000001 of the concentrations at neutral- 

 ity, we obtain the value 



K - 0.00000000000001 



u ra\ 0.00000000000001 

 whence (H) = 



(OH) 



1 This corresponds with the requirements of the Mass- 

 Law. 



