38 MORRIS LOEB 



solutions of their respective bases, and finally of the bases 

 with one another. 



But if solutions are mixed together which are not "iso- 

 hydric," the resultant conductivity will be greater than 



ma , if calculation shows that the stronger acid is thereby 

 m+n 



partially reassociated and the weaker partially dissociated, 

 while it will be less than the normal if the stronger acid is 

 being dissociated and the weaker reassociated. This depends 

 upon the fact that the dissociation of the same number of 

 molecules produces a relatively greater effect when the acid 

 is farther from the limit of dissociation which all approach 

 asymptotically. In keeping with these facts is Nernst's ob- 

 servation that the solubility of a salt is decreased by the pres- 

 ence of compounds having a common ion with it; thus the 

 solubility of silver acetate is equally affected by the pres- 

 ence of silver nitrate and sodium acetate. 



10. The theory of "isohydric" solutions leads up to the 

 important point of the neutralization of acids by bases. In 

 the first place, salts in dilute solutions are no longer con- 

 sidered to be the product of a reaction like the following : 



KOH+HC1 =KC1+HOH. 



Where there is perfect dissociation, at extreme dilutions, 

 the reaction is represented thus : 



K+OH+Cl+H=K-fCl+HOH. 



At greater concentrations this is accompanied by a certain 

 reassociation of K-j-Cl and a dissociation K, OH and H, Cl, 

 but K+C1 is supposed to be very small in all cases, as the 

 dissociation of salts proves to be relatively very great. Neu- 

 tralization would therefore practically mean a formation of 

 water from H and OH, and salts as such would only exist in 

 concentrated solutions or as a combination of a very weak 

 acid with a very weak base. A result of this would be that 



