1902.] on the Electronic Theory of Electricity. 179 



2. That at greater distances positive electrons must repel positive 

 and negative repel negative, but unlike electrons attract, with a force 

 which varies inversely as the square of the distance. 



3. Superimposed on the above there must be a resultant effect such 

 that all atoms attract each at distances great compared with their size 

 without regard to the relative number of positive and negative 

 electrons which compose them, inversely as the square of the 

 distance. 



In this last condition we have the necessary postulate to account 

 for universal gravitation in accordance with Newton's law. 



It is conceivable, however, that this differential or resultant uni- 

 versal attraction to which gravitation is due, is only true of electrons 

 when gathered together so as to form atoms. In order words, every 

 atom attracts every other atom ; but every electron does not attract 

 every other electron. Universal gravitation may be an effect due to 

 the collocation of electrons to form atoms and molecules, but not an 

 attribute of electrons in themselves, though, if the gravitative effect 

 is proportional to the product of the total number of electrons in each 

 mass, the Newtonian law will be fulfilled. It has been also suggested 

 that a sufficient source for the necessary resultant mass attraction 

 may be found in a slight superiority of the attractive force between 

 two opposite electrons over the repulsion between two similar 

 electrons. 



Conclusion. 



In the above sketch of the electronic theory we have made no 

 attempt to present a detailed account of discoveries in their historical 

 order or connect them especially with their authors. The only object 

 has been to show the evolution of the idea that electricity is atomic 

 in structure, and thus these atoms of electricity called electrons attach 

 themselves to material atoms and are separable from them. These 

 detachable particles constitute as far as we yet know negative elec- 

 tricity. The regular free movements of electrons create what we call 

 an electric current in a conductor, whilst their vibrations when 

 attached to atoms are the cause of aether waves or radiation, whether 

 actinic, luminous, or thermal. The SBther can only move and be 

 moved by electrons. Hence it is the electron which has a grip of the 

 aether and which, by its rapid motions, creates radiation, and in turn 

 is affected by it. We have therefore to think of an atom as a sort of 

 planet accompanied by smaller satellites which are the electrons. 

 Moreover the electrons are capable of an independent existence, in 

 which case they are particles of so-called negative electricity, The 

 atom having its proper quota of electrons is electrically neutral, but 

 with electrons subtracted, it is a positive atomic ion, and with 

 electrons added to it it is a negative atomic ion. It has been 

 shown from a quantitive study of such diverse phenomena as the 

 Zeeman effect, the conductibility produced in gases by Rontgeu rays 



N 2 



