20 Mr. W. Sutherland on Ionization in Solutions 



row for each solute contains 100 K(l — X/^o)/(yin)^(t c — t)v 9 .. 

 which I have found empirically to be constant, so that 

 l/v(t c —t) is proportional to the unknown I. 







Table VI 









Temp 



18°. 



140°. 



218°. 



281°. 



306°. 



K 



81-2 



44-8 



26'0 



13-3 



8-93 



v 



1-001 



1-088 

 NaCl. 



1-186 



1-336 



1-434 







(1-x/a o )A0(v0* 



0-306 



0-448 



0-573 



0-745 



0-877 





86 



82 



KCl. 



85 



88 



93 



(l-X/A )/10(v lW )* 



0-321 



0-468 



0-577 



0-713 



0-853 





75 



86 



80 



84 



90 



From this table we draw the conclusion that if K enters 

 as in (10), I is inversely proportional to v(t c — t). Now the 

 induction of Walden, given in the last section, shows that K 

 does enter as in (10) ; so we infer that the force causing 

 ionization varies inversely as v(t c — t). But apart from 

 theoretical considerations I have noticed empirically that 



(fe-*)*(l— VMAOO'in)*" is constant, . . (22) 



as is shown by the following values derived from Table VI. : 



NaCl ... 6'S 6-7 7-0 6S 6-7 

 KCl . . . 6-0 7-0 7-1 6-5 6-5 



But interest centres in the clue given by Table VI. to the 

 law of I, namely, that it varies inversely as v(t c — t). 



Now, according to the law of Eotvos, the surface-energy 

 per molecule in a liquid is proportional to t c — t ; and in 

 *'The Principle of Dynamical Similarity in Molecular 

 Physics " (Boltzmann Festschrift, p. 373), I have sought 

 to show the dynamical basis for that law. We have t c — t 

 serving as a measure for a certain supply of potential energy 

 in the solvent ; and the force causing ionization in a given 

 solvent at different temperatures varies inversely as this 

 potential energy. To follow this interesting inquiry farther, 

 special experiments on a variety of solvents, like those of 

 Walden, will have to be carried out over ranges of tem- 

 perature like those of Noyes and Coolidge. The result 

 seems paradoxical, that the ionizing force should be inversely 

 as the molecular potential energy ; but the electrical force 

 drawing the ions together is inversely as K, so that in a 

 liquid like water, in which molecular potential energy and K 



