1902.] on the Electronic Theory of Electricity. 171 



success which has so far attended this effort to create a new range of 

 electrical conceptions. Let us consider first the fundamental difference 

 between substances in respect of electrical conductivity. In the elec- 

 tronic theory, what is the distinction between conductors and non-con- 

 ductors ? It must be remembered that on the electronic hypothesis an 

 electric current is a movement of electrons. Hence a conductor must 

 be a substance in which electrons free to move exist. It is considered 

 therefore that in metals and good conductors a certain proportion of 

 the atoms are broken up into positive and negative ions or into elec- 

 trons and remainders of atoms which we may call coelectrons. There 

 may be a constant decomposition and recomposition of atoms taking 

 place, and any given electron so to speak flits about, now forming 

 part of one atom and now of another and anon enjoying a free exist- 

 ence. It resembles a person visiting from house to house forming a 

 unit in different households and in between being a solitary person in 

 the street. In non-conductors, on the other hand, the electrons are 

 much restricted in their movements, and can be displaced a little way 

 but are pulled back again when released. The positive and negative 

 ions or electrons and coelectrons never have the opportunity to part 

 company very far. 



The reader who is familiar with the modern doctrine of the ioniza- 

 tion of salts in solution will see that a close similarity exists between 

 this view of the atomic state of a metal and the chemical state of a 

 salt in solution. The ionic theory of solution is that if some salt, say 

 sodic chloride, is placed in water a certain proportion of the molecules 

 of sodic chloride are dissociated into sodium and chlorine ions, that is 

 to say, atoms possessing electric charges, and the electric conductivity 

 of the solution is due to the mobility of these saline ions. 



On the electronic theory a certain proportion of the atoms of 

 a conductor are similarly in a state of electronization. The application 

 of an electromotive-force to the conductor thus at once causes the 

 electrons to begin to migrate. If we compare conductors and non- 

 conductors we shall see that the former are mostly elementary bodies, 

 the metals and alloys or graphitic carbon, whilst the latter are all 

 very complex substances such as glass, ebonite, the oils, shellac, 

 gutta-percha, etc. These last have large and complex molecules, but 

 the good conductors have all simple molecules and small atomic 

 volumes. The exceptions apparently are sulphur and carbon in the 

 form of diamond. When, however, we remember that carbon and 

 sulphur are elements very prone to polymerise and so to speak com- 

 bine with themselves they may not really be an exception. The 

 electrons may, therefore have much more difficulty in exchanging 

 from atom to atom or in making their way between or through the 

 molecules when these are very complex than when they are 

 simple. 



The question then may be asked why these free electrons do not 

 all escape from the conductor. The answer is that there must be an 

 equal quantity of electrons and coelectrons or remainflers of atoms 



