THEORIES OE ELECTROLYSIS. 



299 



lated from the depression of the freezing point with its value 

 as found from the conductivity. The following are some of 

 the results given by H. C. Jones : — x 



While the small differences probably indicate that second- 

 ary effects will ultimately have to be investigated, the 

 striking general agreement shows that the condition of the 

 molecules which makes them electrolytically active is also 

 the chief cause of the increase in the osmotic pressure and 

 of the existence of chemical activity. 



So much seems to follow from the facts of the subject. 

 We must now consider the hypotheses which have been 

 framed in order to explain the physical meaning of ionisa- 

 tion. It is well known that the osmotic pressure of a sub- 

 stance in dilute solution not only obeys all the ordinary 

 gaseous laws, but also has the same numerical value as the 

 pressure which the same amount of substance would exert, 

 in the same volume, were it to exist in the gaseous con- 

 dition. Whether or not it follows from this that the mechan- 

 ism of osmotic pressure, like that of gaseous pressure, is 

 due to molecular impacts, is perhaps doubtful. It may 

 be that finely divided matter must necessarily possess such 

 properties, whatever be the ultimate physical explanation. 

 Nevertheless, the agreement of dilute solutions with the 



1 Zeits. fiir physikat. Chemie, xii., p. 639, 189- 



