ON THE PHYSICAL VIEW OF NATURE. 1G5 



Tho decisive step was taken in 1887 by Arrhenius/ whu 

 has the merit of having brought together the two inde- 

 pendent courses of research and reasoning, and made 

 them fruitful for each other. He shows - " that the dif- 

 ference between active and inert molecules consists in 

 this, that the former are split into tlieir ions, the latter 

 not. Only the free ions take part in tlie conduction of 

 electricity and in chemical reactions : this is the rea.son 

 for the proportionality of the two (Faraday's law). The 

 ions behave in solution like independent molecules : this 

 is the reason of the deviation which electrolytic solutions 

 show from the extended gaseous laws (Van't Hott's dis- 

 covery)." " What a change has come over our concep- 

 tions," exclaims Victor ]\Ieyer,^ " if we have to accustom a. 



. , Victor 



ourselves to see in a dilute solution ot common salt, no Meyor^.n 

 longer the undecomposed molecules of a salt, but separate ^^^'^^^ 

 atoms of chlorine and sodium. For these revolutionary 

 innovations we are indebted to the labours of Van't 

 Hoff, Arrhenius, Ostwald, Planck, Tfeffer, de Vries, but, 

 so far as experiments go, notably to the splendid re- 

 searches of Kaoult, wliich for years have been prepar- 

 ing the way for this miglity theoretical advance." 



The year 1887, which brought together these two 

 fruitful lines of reasoning and research, can also be con- 

 sidered as the epocli wlien the new science of physical 

 chemistry was fairly laiiiiclied into existence. The year 



1 In a communication to the I Address by Victor Meyer before 

 Academy of Stockholm of 8th June the German " Naturforscherver 



and 9th November 1887. 



- Quoted from Ostwald's ' Allge- 

 meine Chemie,' 2nd ed., vol. ii. 

 part 1, p. 656. 



^ See the highly interesting 



sammlung" at Heidelberg in 1S89, 

 entitled " Chemische IVobleme 

 der Gegcnwart " (Heidelberg, 

 1890), p. 32. 



