26 On the Theory of Dissociation into Ions. 



MR and M'R' might collide under such circumstances that M' 

 might come nearer to R than M was, and, consequently, M'R 

 would be the result ; whether, however, M and R' would find 

 themselves in such close proximity that they would instantly 

 combine together, or whether they might remain for a time 

 actually free, is a question which our ignorance of the distances 

 and forces concerned do not allow us to settle. Williamson's 

 theory (Phil. Mag.) was practically identical with Clausius's 

 second proposition — continual interchange of radicals, but 

 not necessarily the presence of free atoms. Clausius's theory 

 was proposed to account for the facts of Electrolysis, William- 

 son's to account for Chemical facts. Nothing which has come 

 to light since that time seems to have shaken the idea of a 

 continual interchange of atoms in the molecules of a liquid ; 

 there seem, however, to be decided objections to the concep- 

 tion of free atoms being present. Whether it is probable that 

 in a liquid at ordinary temperatures there can be any mole- 

 cules as hot as the dissociation temperature (which is probably 

 1000° to 2000°) or not, is a matter of opinion ; but if any 

 free atoms are present the chances of their meeting atoms 

 of the same nature would be equal to those of their meeting- 

 atoms of the opposite nature: with the former they would 

 combine just as they do with the latter, and the result would 

 be that hydrogen and chlorine gas would be formed, and the 

 acid would gradually become entirely decomposed : nor can 

 it be argued that the similar charges on the free atoms of the 

 same substance would prevent these combining, for in the 

 analogous case of hydriodic acid we know as a fact that free 

 iodine is produced when the acid is heated to its dissociation 

 temperature. 



It does not seem necessary, however, to imagine the presence 

 of free atoms to explain the phenomena of electrolysis (cf. 

 Lodge, B. A. Report, 1887, p. 338). The facts of the case, I 

 believe, are that although an E.M.F. of finite magnitude is 

 required to produce sensible electrolysis, i. e. the liberation of 

 gas, &c. in recognizable quantities, any electromotive force 

 will produce results indicative of electrolysis, these results 

 being a gradual leakage of electricity, and a reverse or 

 polarization current on removing the battery. The leakage 

 may be explained by the electrolysis of those molecules which 

 happen to be at a temperature above that of the average 

 molecule, and decomposable by a lower E.M.F. than is the 

 average molecule, or else by the action of the E.M.F. on those 

 dissimilar atoms which at the moment when they lose their 

 original partners find themselves comparatively very far apart 

 from each other (M and R' in the case above cited). As to 



