996 



SCIENCE. 



[N. S. Vol. XVII. No. 443. 



has long been 'in the air' of science, wait- 

 ing to take more definite development. 

 Our minds are gradually getting accus- 

 tomed to the idea of the genesis of the 

 elements, and many of us are straining 

 for the first glimpse of the resolution of 

 the chemical atom. We are eager to enter 

 the portal of the mysterious region too 

 readily ticketed 'Unknown and Unknow- 

 able.' 



Another phase of the dream now de- 

 mands attention. I come to the earlier 

 glimpses of the electric theory of matter. 



Passing over the vague speculations of 

 Faraday and the more positive speculations 

 of Sir William Thomson (now Lord Kel- 

 vin), one of the earliest definite statements 

 of this theory is given in an article in the 

 Fortnightly Review for June, 1875, by 

 W. K. Clifford— a man who in common 

 with other pioneers shared that 'noblest 

 misfortune of being born before his time.' 

 'There is great reason to believe,' said 

 Clifford, 'that every material atom carries 

 upon it a small electric current, if it does 

 not wholly consist of this current.' 



In 1886 when president of the Chemical 

 Section of the British Association, in a 

 speculation on the origin of matter, I drew 

 a picture of the gradual formation of the 

 chemical elements by the workings of three 

 forms of energy — electricity, chemism and 

 temperature— on the 'formless mist' (pro- 

 tyle*), wherein all matter was in the pre- 

 atomic state — potential rather than actual. 

 In this scheme the chemical elements owe 

 their stability to being the outcome of a 

 struggle for existence— a Darwinian de- 

 velopment by chemical evolution— a sur- 

 vival of the most stable. Those of lowest 



* We require a word, analogous to protoplasm, 

 to express the idea of the original primal matter 

 existing before the evolution of the chemical ele- 

 ments. The word I venture to use is composed 

 of Trp6 {earlier than) and v?!.?/ (the stuff of which 

 things are made) . 



atomic weight would first be formed, then 

 those of intermediate weight, and finally 

 the elements having the highest atomic 

 weights, such as thorium and uranium. I 

 spoke of the 'dissociation point' of the 

 elements. "What comes after uranium?" 

 I asked. And I answered back, "The re- 

 sult of the next step will be * * * the 

 formation of * * * compounds the disso- 

 ciation of which is not beyond the powers 

 of our terrestrial sources of heat." A 

 A dream less than twenty years ago, but 

 a dream which daily draws nearer to en- 

 tire and vivid fulfilment. I will presently 

 show you that radium, the next after uran- 

 ium, does actually and spontaneously dis- 

 sociate. 



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 experi- 

 ment.* Faraday, W. Weber, Laurentz, 



* " The equivalent weights of bodies are simply 

 those quantities of them which contain equal 

 quantities of electricity; * * * it being the elec- 

 tricity which determines 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 equivalents to 

 each other in their ordinary chemical action, have 

 equal quantities of electricity naturally associated 

 with them." Faraday's ' Experimental Researches 

 in Electricity ' par. 869, January, 1834. 



" This definite quantity of electricity we shall 

 call the molecular charge. If it were known 

 it would 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. * * * Eor each chemical 

 bond which is ruptured within an electrolyte a 

 certain quantity of electricity traverses the elec- 

 trolyte, which is the same in all eases." G. John- 

 stone 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." Helmholtz, Faraday Lecture, 

 1881. 



