Prof. Norton on Molecular Physics. 103 



Conduction. — We have seen that the act of polarization com- 

 prises two different processes — a movement of a certain portion 

 of the aether of the atmosphere of a molecule from one side to 

 another, and contemporaneously with this a discharge of aether 

 from the one side, and an absorption of a corresponding quan- 

 tity upon the other side. Now the electric constitution of two 

 different bodies may be such that with the one the same amount 

 of electric movement from particle to particle may be accom- 

 panied by a feeble degree of polarization, and with the other 

 by a much greeter degree. The polarization is a change deter- 

 mined originally by the forces propagated by the universal 

 aether, while the outward flow of the electricity is partly the 

 result of the mutual repulsion between contiguous atoms of the 

 electric aether. 



Let us suppose two extreme cases compatible with our gene- 

 ral theory. (1) Let there be an indefinite line of molecules, 

 such that the density of the aether between them is the same as 

 at the surface of the molecular atmospheres, and suppose a 

 quantity of free electricity to arrive at one end of this line. It 

 is plain that the repulsive energy of this electricity will urge 

 before it a certain quantity of electricity throughout the whole 

 length of the line, and that if the flow be unchecked it can exert 

 little or no disturbing action upon the molecular atmospheres 

 except very near their surface, and cannot polarize them. To do 

 this, the moving electricity must have a certain decided tension — 

 that is, be present in a certain sufficient quantity at each point 

 of the line. This would be the case of perfect, or nearly perfect 

 conduction, and there would be little or no polarization of the 

 molecules. (2) Let us suppose that the density of the electric 

 aether is very feeble between the molecules ; there being now no 

 continuous mass of aether to give way before the electricity re- 

 ceived at the end, the latter will, as a first effect, exert its repul- 

 sive action through the universal aether upon the atmospheres of 

 the nearer molecules and polarize them, and this will extend 

 through the line, and the polarization will determine the dis- 

 charge in the manner already explained. This would be the 

 case of a non-conducting dielectric medium. In all actual in- 

 stances of good conduction the case lies between these two ex- 

 tremes : the greater part of the electric movement is confined 

 to the outer envelope of the atmosphere, and the outer portion 

 of the inner envelope ; and the polarization resulting from the 

 disturbance of the lower envelope, or the atmosphere proper, is 

 slight. With non-conductors, or poor conductors, the flow near 

 the surface of the lower envelope, around the molecule, resulting 

 from the direct repulsive action (or elastic tension) of the electric 

 aether, is comparatively slight ; and the polarization of the lower 



