THE THIRST OF SALTED WATER 649 



not of the order of gaseous dissociation — that the behaviour of 

 hydrogen chloride was not that of ammonium chloride. 



After 1893 my interpretation was paraphrased, in consequence 

 of a suggestion made by J. J. Thomson and Nernst independently, 

 that the cause of dissociation was the high specific inductive 

 capacity of water. The attempt was then made to show that 

 substances generally of high specific inductive capacity were 

 active in promoting dissociation — but this turned out to be a 

 signal failure in the main. The argument used by J. J. Thomson 

 is of considerable interest (Phil. Mag. 1893, 36, 320) : 



The view that chemical action is electrolytic in character 

 has been repeatedly urged by Prof. Armstrong. The ability 

 of water to further this kind of action would be much greater 

 if, while the chemical action were going on, the water existed in 

 the liquid than it would if the water were in the gaseous state. 

 If we take the view that the forces which hold the atom in the 

 molecule together are electrical in their origin, it is evident that 

 these forces will be very much diminished when the molecule 

 is close to the surface of or surrounded by a conductor or a 

 substance like water possessing a very large specific inductive 

 capacity. 



Then let AB represent two atoms in a molecule placed near 

 a conducting sphere ; then the effect of the electricity induced 

 in the sphere by A will be represented by an opposite charge 

 placed at A' the image of A in the sphere. If A is very near the 



surface of the sphere, then the negative charge at A' will be 

 very nearly equal to that at A. Thus the effect of the sphere 

 will be practically to neutralise the electric effects of A ; as but 

 one of these effects is to hold the atom B in combination, the 

 affinity between the atoms A and B will be almost annulled by 

 the presence of the sphere. Molecules condensed on the surface 

 of a sphere will thus be practically dissociated. The same effect 

 would be produced if the molecules were surrounded by a 

 substance possessing a very large specific inductive capacity. 

 Since water is such a substance, it follows, if we accept the view 

 that the forces between the atoms are electrical in their origin, 

 that when the molecules of a substance are in aqueous solution 



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