152 HYDROGEN ION CONCENTRATION 



The definition of acid and alkaline reaction would be the same 

 as in aqueous solution; at the neutral reaction [H+] = [0H~], but 

 methods for the determination of the reaction are still lacking. A 

 gas chain with an oily Hquid has not yet been investigated. Nor is 

 the dissociation constant of water (in oil) known 



[H+] [0H-] _ 



H2O 



(where [H2O] represents again a value proportional to the vapor 

 pressure). Doubtlessly it depends to a great extent upon the nature 

 of the oil and especially upon its dielectric constant. In our present 

 state of knowledge it is useless to attempt to apply any indicator 

 method to oil phases. All that can be done at present is to disclose 

 this great gap. 



The principal difference between the two classes of electrolytes, 

 1-acids and bases, 2-salts, appears to be still evident even in solvents 

 with small dielectric constants. In this connection also H- and 

 OH-ions exhibit their specific pecuharity. This is all the more 

 remarkable, since the other peculiarity of the H- and OH-ions, 

 i.e., their abnormally high conductivity, is not in evidence in these 

 solvents. H- and OH-ions, for example, have no greater motility 

 in organic water-free solvents than alkali or halogen-ions. The 

 abnormally high conductivity of H- and OH-ions was explained by 

 Arrhenius in the following way: When a moving H-ion comes in 

 contact with a H20-molecule, it combines with the OH-group of 

 the latter which immediately liberates its H-group as an H+-ion. 

 In this way in the process of conduction the portion of the path cor- 

 responding to the thickness of the H20-molecule is saved, and an 

 apparent impression of an abnormally high motility of the H-ion 

 results. The same holds for the OH-ion. In general it appears 

 that in every solvent those ions which the solvent itself is capable 

 of yielding possess an abnormally high conductivity. This theory, 

 is similar to the one once proposed by Grotthus concerning general 

 electrolytic conduction, and which had been dominant before the 

 Arrhenius theory of dissociation appeared. 



