Theory of Electrolytic Dissociation, "215 



osmotic pressure, sought to show that dilute solutions obey 

 the gas laws. In this he was unsuccessful, in that he had to 

 introduce the factor i above mentioned, which varies for 

 different solutes in the same solvent, and even for different 

 concentrations of the same solute in a given solvent. An 

 examination of the original tables published by Arrhenius* 

 shows that the factor i is by no means always unity for 

 aqueous non-electrolytic solutions, nor does it always vary 

 more from unity in the case of solutions of very considerable 

 conductivity than in the case of non-electrolytes ; but for a 

 goodly number of excellent electrolytes i is materially greater 

 than unity. The latter fact was utilized by Arrhenius in his 

 endeavour to show that the factor i exceeds unity for electro- 

 lytic conductors, and increases with the dilution as does the 

 so-called molecular conductivity. And thus upon the assump- 

 tion that free ions, part-molecules charged with electricity, 

 exist in an electrolyte and act like so many molecules, the 

 general statement which van't Hoff had made for solutions 

 was upheld — namely, that dilute solutions having the same 

 temperature and the same osmotic pressure contain the same 

 number of dissolved molecules. 



Now I wish to contend that the facts presented by Arrhenius 

 in his original article are not sufficient to serve as a basis for 

 the assumption of electrolytic dissociation in solutions ; and 

 that while isolated facts may here and there be interpreted 

 by means of the dissociation theory, the bulk of experimental 

 evidence gathered since 1887 speaks strongly against the 

 theory. 



In 1901 1 I published a list of results of cryoscopic and 

 ebullioscopic determinations made with typical aqueous 

 solutions of electrolytes and non-electrolytes, and also a list 

 of molecular-conductivity determinations of the same electro- 

 lyte- at 0° and at 95°. It is unnecessary to discuss again the 

 details of these results, which are rather voluminous. Suffice 

 it to state that a comparison of the freezing-point values with 

 the molecular conductivity at 0°, and also of the boiling-point 

 values with the molecular conductivity at 95 3 , revealed the 

 fact that there is no such connexion between freezing-points 

 and boiling-points of solutions on the one hand, and their 

 conductivity on the other, as is claimed by the theory of 

 Arrhenius. In numerous cases not even a qualitative agree- 

 ment exists. The facts presented in the paper cited have 

 since been corroborated by Sraits in his careful vapour-tension 

 measurements, and by H. C. Jones and co-workers in their 



• Zeit. phu8. Chem. i. p. 629 (1887). 

 t Jour, phj/s. Chem. v. p. 339 (1001). 



