22 POPULAR SCIENCE MONTHLY. 



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

 when gathered together so as to form atoms. In other 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 electricity. 

 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 aether 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 there- 

 fore 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 quantitative study of such diverse phenomena as 

 the Zeeman effect, the conductibility produced in gases by Eontgen 

 rays or by ultra violet light and from the magnetic deflection of 

 kathode rays, that in all cases where we have to deal with free moving, 

 or vibrating electrons, the electric charge they carry is the same as that 

 conveyed by a hydrogen atom in electrolysis. 



There is good ground for the view that when a gas is made incan- 

 descent, either by an electric discharge or in any other way, the 

 vibrating bodies which give rise to the light waves are these electrons 

 in association with the atom. The energy of mass movement of the 

 atom determines temperature, but the fact that we may have light given 

 out without heat, in short, cold light, becomes at once possible if it is the 



