Theory of Amp/ioteric Electrolytes. 27 1 



" Theory of Amphoteric Electrolytes. Part II." By JAMES 

 WALKER, F.K.S., University College, Dundee. Received 

 October 19, Eead November 17, 1904. 



In a previous paper* it was shown that if HXOH is an amphoteric 

 electrolyte, it is possible to express the concentration of the various 

 ions present in its aqueous solution in terms of the concentration of 

 the unionised substance, the dissociation constants of the substance 

 acting as acid and as base respectively, and the ionisation constant of 

 water. As the expressions obtained will be frequently used in the 

 presei)t paper, I reproduce them here in their original form, suitable 

 for calculation when the electrolyte is preponderantly acid, and also in the 

 form which would be used when the substance is preponderantly basic. 

 The active masses of the various substances present at equilibrium are 

 represented as below, the dissociation constants of acid, base and water 

 being denoted by k a ^kb, and K respectively 



H + OH- XOH- HX+ HXOH + X 



abed u 



- 



c = k a u/a ....................... (3). c = ub ........................ (3'). 



K. 



d = ua ........................ (4). d = k b u/b ........................ (4'). 



It was further shown that in the case of the amino-benzoic acids 

 investigated by Ostwald and by Winkelblech an application of the 

 theory accounted for the abnormalities exhibited by these acids, and 

 in particular led to the deduction of values of the molecular conduc- 

 tivity which were in satisfactory accordance with those observed. A 

 thorough recalculation of the results shows that the more strictly the 

 theory is applied the better is the correspondence between theory and 

 experiment. Owing to a systematic error in the first calculation, the 

 values given for d were, when the ratio &&/K was large, somewhat too 

 high, the total concentration 77 = 1/v having been taken in the calcula- 

 tion by inadvertence equal to u + a + d instead of equal to u + a + 2d. 

 The latter result is deduced as follows: The total concentration, 

 corresponding to the composition of the solution as made up in the 



* ' Roy. Soc. Proc.,' vol. 73, p. 155, 1904 ; also ' Zeitschriffc fur physikalische 

 Chemie,' vol. 49, p. 82. 



