MODERN VIEW« ON MATTEE. 233 



elements having the highest titoniic weights, such us thorium ;ind 

 uranium. I spoke of the " dissociution point" of the elements, 

 ' ' What comes after uranium 'i "" I asked. And I answered back — ' ' The 

 result of the next step Avill be * * " the formation of * * * 

 compounds the dissociation of which is not beyond the powers of our 

 terrestrial sources of heat." A dream less than twenty years ago, but 

 a dream which daih" draws nearer to entire and vivid fultillment. I 

 will presently show 3'ou that radium, the next after uranium, does 

 actually and spontaneously dissociate. 



The idea of units or atoms of electricity — an idea hitherto floating 

 intangibly like helium in the sun — can now be brought to earth and 

 submitted to the test of experiment." Faraday, W.Weber, Laurentz, 

 Gauss, Zollner, Hertz, Helmholtz, Johnstone Stoney, Sir Oliver 

 Lodge, have all contributed to develope the idea, originally due to 

 Weber, which took concrete form when Stoney showed that Faraday'^ 

 law of electroh^sis involved the existence of a definite charge of elec- 

 tricity associated with the ions of matter. This definite charge he 

 called an electron. It was not till some time after the name had been 

 given that electrons were found to be capable of existing separately. 



In 1891, in my inaugural address as president of the Institution of 

 Electrial Engineers,^ I showed that the stream of cathode rays near the 

 negative pole was alwa3^s negatively electrified, the other contents of 

 the tube being positively electrified, and I explained that ''the division 

 of the molecule into groups of electro-positive and electro-negative 

 atoms is necessary for a consistent explanation of the genesis of the 

 elements." In a ^^acuum tube the negative pole is the entrance and 



""The equivalent weights of bodies are simply those quantities of them which 

 contain equal quantities of electricity; * * * it being. the electricity which deter- 

 mines the equivalent number, because it determines the combining force. Or, if we 

 adopt the atomic theory or phraseology, then the atoms of bodies which are equiva- 

 lents to each other in their ordinary chemical action, have equal quantities of 

 electricity naturally associated with them." — Faraday's Experimental Researches in 

 Electricity, jjar. 869, January, 1834. 



"This definite quantity of electricity we shall call the molecular charge. If it 

 were known it v^ould be the most natural unit of electricity." — Clerk Maxwell's 

 Treatise on Electricity and Magnetism, first edition. Vol. I, 1873, p. 311. 



"Nature presents us with a single definite quantity of electricity. * * * For 

 each chemical bond which is ruptured within an electrolyte a certain quantity of 

 electricity traverses the electrolyte, which is the same in all cases." — (i. Johnstone 

 Stoney, On the Physical Units of Nature, British Association meeting, Section A, 1874. 



"The same definite quantity of either positive or negative electricity moves always 

 with each univalent ion, or with every unit of affinity of a multivalent ion." — Helm- 

 holtz, Faraday Lecture, 1881. 



"Every monad atom has asso(M:ilc(l witli it a certain definite ciuautity of (■Icctricity; 

 every dyad has twice this (piantit}' associated with it; every triad tliree times as 

 much, and so on." — O. Lodge, On I'-lectrolysis, British Association Keport, 1885. 



'' Electricity in Transitu: from Plcniuii to Vaiiiinii (Jouni. List. Ele(;trical Engineers, 

 Vol. XX, p. 10, January 15, 1891). 



