294 MR. W. R. BOUSFIELD AND DR. T. M. LOWRY ON THE ELECTRICAL 



not sufficiently pronounced to justify the unsupported assertion that their behaviour 

 was due to the phenomenon now under discussion, but, when placed side by side 

 with the curve showing the intrinsic conductivity of sodium hydroxide, the behaviour 

 of these salts affords a striking confirmation of the view that the behaviour ot 

 sodium hydroxide is not unique, but is characteristic of the whole group of 

 autolytes. 



Owing to the great ionising power of water, the conductivity of dilute aqueous 

 solutions is usually almost entirely heterolytic. With non-aqueous solvents it is 

 often quite otherwise, and it is even possible that in certain cases the conductivity of 

 the solution may be wholly autolytic. Thus it is stated that acetone and formic acid 

 give conducting solutions of the autolytes KC1, KBr and KI, but not of the heterolytes 

 HC1, and CC1 8 * C0 2 H (see WALDEN and CENTNERSZWER, ' Zeit. Phys. Chem.,' 

 1902, vol. 39, p. 564), a result that is most easily explained by supposing that the 

 acetone acts merely as a solvent, but is not able to bring about heterolytic con- 

 duction. 



The task of distinguishing between autolytic and heterolytic conduction is greatly 

 facilitated by the fact, which is brought out very clearly in the curve showing the 

 intrinsic conductivity of sodium hydroxide at different concentrations, that whilst 

 heterolytic conductivity rises to a maximum in the most dilute solutions, autolytic 

 conductivity is greatest in the most concentrated solutions. The existence of 

 autolytic conductivity affords, therefore, a simple explanation of the increase of 

 molecular conductivity with concentration that has been not infrequently observed. 

 Two examples of this kind were recorded by EULEB (' Zeit. Phys. Chem.,' 1899, 

 voL 28, p. 622), who attributed the increase with concentration of the molecular 

 conductivity of sodium bromide and iodide to the influence of the salt in increasing 

 the ionising power of the solvent, that is, to an indirect, rather than to a direct, 

 autolytic influence. In two of the cases recorded by KAHLENBEHG (' Journ. Phys. 

 Chem.,' 1903, vol. 7, pp. 254-258) the molecular conductivity (of silver nitrate and of 

 ferric chloride in amylamine) did not increase continuously with the concentration, 

 but reached a maximum and then decreased ; it is clear, however, that in these 

 solutions the final decrease of molecular conductivity may be attributed to the 

 great viscosity of the concentrated solutions, to which reference is made in the 

 paper. It is of interest to note that KABLUKOFF (' Phys. Chem.,' 1889, vol. 4, 

 p. 429) noticed an increase with concentration in the molecular conductivity of 

 hydrogen chloride dissolved in ether ; this may perhaps be attributed to the autolytic 



0* H \ /H 

 conductivity of the oxonium salt n 2 H/O\cr Similar observations have been 



made more recently by MclNTOSH and ARCHIBALD (' Roy. Soc. Proc.,' 1904, vol. 73, 

 pp. 454-455) and by J. W. WALKER ('Trans. Chem. Soc.,' 1904, vol. 85, 

 pp. 1082-1098). 



