162 Prof. J. Walker. [Feb. 3, 



k x 10 5 calculated from a = a + d/5 and a = a + d/Q. 



V. 



Tc b \K = 0. 





Jc b jK = 10. 



h b \K = 100. 



fo/X=1000. 



a + d/o. 



a + d/6. 



a + d/5. 



a + dl6. 



a + djo. 



a + dj6. 



a + dlZ. 



a + dj6. 





a + d/6. 



10 

 100 



1000 



1-0 

 1-0 

 10 



1-0 

 1 -o 



10 



0-944 

 0-992 

 0-993 



0-938 

 0-991 

 0-993 



0-718 

 0-947 

 0-991 



679 

 -940 

 0-988 



0-7S0 

 0-710 



0-936 



0-622 

 0-672 

 0-930 



3 30 

 0-73 

 0-69 



2-62 

 0-58 

 0-65 



the true value. For kj,/K =100 we have in the ordinary range of 

 dilutions a fall to a minimum for k , which is apparent when a = a + d/5 

 is used, and also occurs between v = 10 and v = 100 when cc = a + d/6 

 is employed. In this case k at 0=1000 is about 7 per cent, beneath 

 the true value of k a . Finally, with h/K = 1000 the value of k at v = 10 

 greatly exceeds the true value, and falls very rapidly with the dilution 

 to reach a minimum at high dilutions which will generally appear in 

 the usual range investigated. Here k at v = 1000 is 30 — 35 per cent, 

 short of the true value. 



For other values of k a than that used in the above calculations the 

 change in the value of k with the dilution is similar, because, as may be 

 deduced from the formulas on pp. 157 — 158, the relative values of a for 

 two electrolytes with the same ky do not vary greatly with the dilution, 

 being at all dilutions approximately proportional to the square roots of 

 the acid constants as long as u does not differ sensibly from 1 [v. 



Turning now to the experimental data, we find that Ostwald obtained 

 for ortho-amino-benzoic acid, 1 : 2-NH L >Ct3H 4 COOH, values of k which 

 steadily increased with increasing dilution,* confirmation of this result 

 being subsequently furnished by Winkelblech.f Their numbers are 

 given in the following table : — 



v. h (Ostwald). k (Winkelblecli). 



64 0-66 xlO" 5 0-65 x 10~ 5 



128 0-74 0-74 



256 0-84 0-84 



512 0-92 0-91 



1024 0-96 0-97 



Ostwald accounted for the rise in the value of the constant by 

 adopting a suggestion of Wislicenus, that double molecules might be 

 formed according to the scheme referred to on p. 156, and that the 

 breaking up of these double molecules at increasing dilutions into 

 simple ionisable molecules would occasion a greater increase of ionisa- 



* Ostwald,. 'Zeit. fur physikal. Cliem.,' vol. 3, p. 261 (1889). 

 f Winkelblecli, loc. cit., p. 564. 



