﻿or Atom of Electricity. 419 



Professor Helinholtz's announcement was made in Ins 

 Faraday Lecture delivered on the 5th of April, 1881, subse- 

 quent to both the announcements I had made. See the 

 Journal of the Chemical Society for 1881. The announce- 

 ments as made by him and by myself are as follows : — 



G. Johnstone Stoney in Aug. Professor von Helmholtz in 

 1874, and again in Feb. April 1881. 

 1881. 



" And, finally, Nature presents " Now the most startling result 



us, in the phenomenon of electro- of Faraday's Law is perhaps this. 



lysis, with a single definite quantity If we accept the hypothesis that 



of electricity which is independent the elementary substances are com- 



of the particular bodies acted on. posed of atoms, we cannot avoid 



To make this clear I shall express concluding that electricity also, 



'Faraday's Law' in the following positive as well as negative, is 



terms, which, as I shall show, will divided into definite elementary 



give it precision, viz. : — For each portions which behave like atoms 



chemical bond which is ruptured of electricity. As long as it moves 



within an electrolyte a certain about on the electrolytic liquid 



quantity of electricity traverses the each ion remains united with its 



electrolyte which is the same in all electric equivalent or equivalents. 



cases. This definite quantity of At the surface of the electrodes 



electricity I shall call E,. If* we decomposition can take place if 



make this our unit quantity of there is sufficient electromotive 



electricity, we shall probably have force, and then the ions give off 



made a very important step in our their electric charges and become 



study of molecular phenomena." electrically neutral." 



(Readers of my paper are requested to bear in mind that it 

 was written so long ago that the Ampere was still understood 

 to mean the electromagnetic unit quantity of electricity of 

 the Ohm series. The term is now always applied to the unit 

 current. Moreover the paper, having been written before 

 (■.Gr.S. units came into use, employs those which had been at 

 an earlier date adopted by the Committee of the British 

 Association on Electrical Standards, viz. the G.M.S., or gram- 

 metre-second system.) 



In this paper an estimate was made of the actual amount 

 of this most remarkable fundamental unit of electricity, for 

 which I have since ventured to suggest the name electron. 

 According to this determination the electron = a tvventiethet 

 (that is 10 -20 ) of the quantity of electricity which was at 

 that time called the ampere, viz. : the quantity of electricity 

 which passes each second in a current of one ampere, using 

 this term here in its modern acceptation. This quantity of 

 electricity is the same as three eleventhets (3x 10" u ) of the 

 C.G-.S. electrostatic unit of quantity. 



