116 SIE WILLIAM KAMSAY 



pressure, which leads to the assumption that the mole- 

 cules of the dissolved substance subsist in the liquid in 

 the same number in unit volume and exert the same 

 pressure as they would if they were capable of assuming 

 the state of gas at the same temperature. This paper was 

 immediately afterwards translated by Ramsay and pub- 

 lished in the Philosophical Magazine. This theory of 

 Van't HofFs was found not to be equally applicable to 

 substances like common sugar on the one hand, and on 

 the other to salts and compounds of saline constitution, 

 such as acids, all of which are electrolytes. And the 

 next step was represented by the hypothesis of Arrhenius, 

 published in 1888, as to the dissociation of such com- 

 pounds into their chemically interchangeable parts or 

 ions. This hypothesis to the supporters of the older 

 doctrine seemed to be contrary to fact and common 

 sense. It may readily be imagined therefore with 

 what animation the discussion proceeded in the joint 

 meetings of Sections A and B. A report of the several 

 speeches was published in the Chemical News and in 

 the Abstracts issued by the Chemical Society, But as 

 so often remarked, the discussions which take place in 

 public on such occasions are often equalled or surpassed 

 in practical effect by the more intimate and informal 

 talk which goes on over the dinner-table or perhaps in 

 the garden or over a pipe at night. One such sym- 

 posium occurred at Leeds in the house of Professor 

 Smithells, who has kindly supplied the following note 

 recording his recollections of what took place : 



