778 Sir J. J. Thomson on the 



naturally be more likely to take place if both A and B were 

 active molecules, L e. if both had exceptionally large electro- 

 static moments. There may, however, be cases in which 

 there is combination, though only one of the molecules, B is 

 of this type. From what we have pointed out on page 770, 

 the approach of B to A will promote the charging up of the 

 atoms in the molecule A, even if they were not charged 

 originally, and thus tend to bring A into the active state even 

 if it were not in that state before its union with B. 



We can readily understand why liquids whose molecules 

 have large electric moments should be able to produce great 

 ionization when electrolytes are dissolved in tbem. For in 

 the first place the molecules of the solvent attach themselves 

 to the molecules of the electrolyte, attract them and thus 

 tend to pull the atoms apart. Secondly, the large electric 

 moment of the molecules will cause the solvent to have a very 

 high specific inductive capacity, so that when the oppositely 

 charged atoms of the electrolyte are once separated, the 

 attraction between them will be diminished ; this diminution 

 in the attraction will diminish their rate of recombination. 

 Since n the number of free ions per cubic centimetre is 



10 



proportional to e~2R0, where iv is the work gained by the 

 recombination of the ions, 6 the absolute temperature and R 

 the gas constant, we see by putting w = iv jK, where w is the 

 work gained when the ions recombine in a medium whose 

 specific inductive capacity is unity, and K is the specific 

 inductive capacity of the solvent, that n will be proportional 



to e 2KK0 : thus when w is large compared with R#, n will 

 increase with great rapidity with any increase in K. Examples 

 of this effect are to be found in the extremely interesting 

 and important series of investigations on the influence of 

 specific inductive capacity on ionization by Walden in a 

 long series of investigations published in the Zeitsclirifb fur 

 Phys. Chem. 



The following table is taken from his paper " Organische 

 Losung- und Ionisierungsmittel," Zeits. fur Pliys. Chem. liv. 

 p. 129. K is the dielectric constant of the solvent, v the 

 dilution required to produce a dissociation of 83 per cent, in 

 a, solution of N(C 2 H 5 ) 4 L 



Another physical property which differentiates the com- 

 pounds with uncharged atoms from those with charged, is 

 that known as electrification by bubbling. When air and 

 other gas bubble through a liquid, such as water, alcohol, 

 acetone, in which there is intra-inolecular ionization, the gas 



