122 THE FITNESS OF THE ENVIRONMENT 



This is the case because the tendency of the 

 electrically charged ions to reunite and form 

 electrically neutral molecules must be less 

 the greater the dielectric constant of the sol- 

 vent. Now the dielectric constant of water 

 is nearly the highest at present known, and 

 therefore ionization in water is on that account 

 also more extensive than in almost any other 

 solvent. 



Finally, for reasons that are not yet under- 

 stood, the process of ionization in other sol- 

 vents than water is a much more complex 

 affair, and there can be no doubt that such 

 complexity limits the phenomena which are 

 dependent upon ionization. 1 



electrostatic attraction between the ions is alone weakened, 

 and hence the degree of dissociation is increased." — Le 

 Blanc, "A Textbook of Electro-Chemistry." New York, 

 1907, p. 147. 



1 "It would be natural to expect that the conceptions 

 which have been found serviceable in the case of solutions in 

 water could be applied directly to solutions in other solvents, 

 keeping in mind that, according to the individual nature of 

 any given solvent, the degree of dissociation, the migration 

 velocity of the ions, and consequently the conductivity of a 

 solution of a given concentration would be different. It is 

 a noteworthy fact, however, that the behavior of non-aque- 

 ous is much more complicated than that of aqueous solutions. 

 This is shown especially by the investigation of the conduc- 

 tivity of solutions of various substances in liquid sulfur dioxide 

 made by Walden and Centnerszwer. Neither the law of the 

 independent migration of the ions, nor the law that by increas- 



