32 Svante Arrhenius on Electrolytic 



Cl(m— w)H 2 (G. Wiedemann's hypothesis) . Now it appears 

 from OstwalcPs researches that the velocity of an ion is the 

 smaller the more atoms it contains. Thus the velocity 

 (which may be easily determined from the conductivity) for 

 the potassium ion of a solution of KG, viz. K.rcH 2 0, must 

 be smaller the greater is the value of n. But Kohlrausch has 

 shown that the ion K.nH 2 travels at the same rate in solu- 

 tions of all the potassium salts, therefore the ion K must be 

 combined with the same quantity of water in all salts. This 

 holds for all other ions. As soon therefore as both the ions 

 ot a salt solution are given, then the hydrate is also known ; 

 and the composition of this hydrate does not alter with the 

 concentration, which certainly does not agree with Mendele- 

 jeff's views. There are, besides, other circumstances (Ostwald, 

 Zeitschr.fur pliysikal. Chemie, ii. p. 840) which make it very 

 probable that in the ions I.nH 2 0, nis extremely small; 

 and this, again, according to MendelejefT is not the case in 

 dilute solutions. But as we have no ground for attributing 

 any particular value to n, and as it is besides probable that 

 many salts {e. g. most of those of potassium) exist only in the 

 anhydrous state, the simplest and likeliest assumption is that 

 the ions of the salts, and consequently the salts themselves, 

 exist in solution without water of hydration. In an analogous 

 way we come to precisely the same conclusion from consider- 

 ing diffusion and the additive properties of salt solutions. 

 The theory of dissociation (contrary to Mendelejeff's asser- 

 tion) is therefore decidedly unfavourable to the assumption of 

 the existence in dilute solutions of hydrates with large quan- 

 tities of water. 



It is well known that for a very long time chemists have 

 been striving to find hydrates in solutions from a considera- 

 tion of the properties of the solutions. Graham some forty 

 years ago lent his support to such a view. The mode of 

 procedure was very simple. Any property, e. g. internal 

 friction (Graham), was taken and tabulated as ordinates 

 against the percentage of substance in solution as abscissas. 

 In the curves thus obtained are some singular points, e. g. 

 maxima, minima, points of inflexion, angular points. In 

 this way Graham found that the internal friction of solu- 

 tions of alcohol in water had a maximum near 36 per cent, 

 alcohol, and concluded therefrom that possibly this compo- 

 sition corresponded to a definite and highly viscous hydrate 

 (perhaps C 2 H 5 OH . 5H 2 0). This conclusion is evidently 

 devoid of any theoretical foundation, and is in fact simply a 

 random shot. Consequently when it was found that the 

 maximum varies with the temperature, this attempt at ex- 



