484 Dr. Harry 0. Jones on the 



by Arrhenius * as probably due to the formation of double 

 molecules of sulphate in the more concentrated solutions, and 

 these are partly broken down with increase in dilution. 



The dissociation of the acids and alkalies as calculated from 

 the lowering of the freezing-point is in general slightly lower 

 than from the conductivity. This would be expected, since the 

 highest conductivity in Kohlrausch's results is probably not 

 that representing complete dissociation. The conductivity 

 value decreases from 0*001 or 0'002 equivalent normal to 

 the greatest dilutions employed t- Doubtless the same cause 

 which produces this real decrease also diminishes the highest 

 value to some extent. A decrease in the true value of /jlco 



would increase the dissociation calculated from-^— . 



It is to be regretted that the freezing-point method could 

 not be extended beyond that dilution where the conductivity 

 value began to decrease. But on account of the very small 

 lowering produced by such dilute solutions, it is even at present 

 impossible. The cause of this decrease in conductivity for the 

 very dilute solutions has been thought to be the carbon dioxide 

 and ammonia in the water. These form compounds with 

 the alkalies and acids respectively, and the molecules of these 

 compounds dissociate into ions with smaller " velocity " than 

 the ions of the original compounds, decreasing the conduc- 

 tivity. The amount of such impurities required to neutralize 

 a considerable per cent, of the acid or base in such dilute 

 solutions would be extremely small. Whether such impurities 

 are the real cause is not positively established by the work 

 of Kohlrausch, as will appear from his own statements %. 

 This explanation is, however, regarded by many as entirely 

 satisfactory. 



Before concluding this division of my paper, which has to 

 do especially with " electrolytic dissociation," it may be of 

 interest to add a word in reference to the so-called " Breaks " 

 which have been claimed to appear when the results from the 

 freezing-point method are plotted as curves. This is the more 

 desirable because of the large number of communications 

 which have recently appeared from Mr. S. Pickering against 

 the " Dissociation Theory/'' I have carefully examined his 

 results in the case of dilute solutions of sodium chloride, and 

 have shown that the " breaks " are caused only by the experi- 

 mental errors in his results § . Mr. Pickering || has applied 



* Arrhenius, Zeits. phys. Chem. ii. p. 497. 



f Kohlrausch, Wied. Ann. xxvi. p. 196. 



j Kohlrausch, torn. cit. p. 204. 



§ Jones, Ber. d. deutsch. Chem. Oesell. xxvi. p. 551. 



H Pickering, ibid. p. 1221. 





