WATER 121 



occur among them, and between them and 

 other substances. 



Such, then, is the process to which are due 

 most of the electrical phenomena and many 

 of the chemical phenomena of solutions, and 

 it is certain that the extent and variety of 

 ionization in water far surpass what is possi- 

 ble in any other solvent. One reason for this 

 is most simple. The ionizing substances are 

 so very much more often soluble in water 

 than in any other solvent, and when soluble 

 are in general so much more highly soluble, 

 that the opportunity for ionization in water 

 is quite unparalleled. Further, ionization in 

 solution unquestionably depends upon the 

 dielectric constant of the solvent, in accord- 

 ance with the principle first stated by Nernst 

 that the greater the dielectric capacity of the 

 solvent, the greater is the degree of electro- 

 lytic dissociation of substances dissolved in it, 

 when the conditions are otherwise the same. 1 



1 "The following consideration will make this principle 

 clearer : The positively and negatively charged ions would 

 unite to form electrically neutral molecules because of the 

 electrostatic attraction which exists between them if it were 

 not for the action of another and opposing force, the nature of 

 which is as yet unknown. The equilibrium between these 

 two forces gives rise to the equilibrium between the ions and 

 the undissociated molecules, or determines the degree of dis- 

 sociation. When the dielectric constant is increased, the 



