±2 inaugural Address by the President 



the direction of the current was always from the chemically 

 active surface of metal through the liquid to the inactive one. 

 A very remaikable expieriment arises from this last-mentioned 

 law. 



You observed that when we dipped these metal plates in the 

 acidulated water the pointer moved to the right, and I told you 

 that in this case the iron was being attacked. We now place 

 them in another solution, a solution of potassium sulphide 

 which attacks the copper most, with the result that the current is 

 reversed, and sends the pointer to the left. It now flows from 

 the copper by liquid to iron. I point especially to this experi- 

 ment with its reversal ot current for a reason which follows 

 later. 



After Faraday's brilliant researches, men's minds seemed to 

 have inclined towards belief in the chemical source of the current 

 till about 1862, when LVrd\Kelvin (then Sir William Thomson) 

 published what he described as a. new proof of Volta's contact 

 force,* which was really, only a very elegant variation of Volta's 

 fundamental experiment,"and does not to my thinking throw 

 any further light on the subject. Lord Kelvin, however, 

 became himself convinced that the contact theory was the true 

 one, and this seems very remarkable when we remember that 

 it is to Lord Kelvin we owe the enunciation of the law (now 

 known as Thomson's law) defining the intimate and exact 

 connection between the electromotive force of the cell and the 

 chemical actions in it. The great authority belonging to Lord 

 Kelvin's high order of genius however swayed the scientific 

 world towards what he accepted as true. 



We have now come to the period when I was tempted to 

 enter the lists. I found then two opposing camps, one led by 

 the genius of Faraday holding that the Voltaic current and all 

 Voltaic action was due to chemical action at the surface of the 

 metal and liquid, the other maintaining that the seat of the 

 force generating the current was at the contact of the two 



8. Papers on Electrostatics and Magnetism, p. 317, 



