ELECTRIC DISTRIBUTION AND CONDENSATION. 57 



influence of attraction from without and repulsion from 

 within, in the direction of the radii. 



If the charge be negative, the potential of surround- 

 ing bodies being higher than that of the sphere, elec- 

 tricity is, in like manner, repelled from the surface 

 toward the center ; and the negative charge takes place 

 on the surface, as the positive charge did in the first 

 instance. Hence the condensation is now in the inte- 

 rior, leaving the surface negative. 



Hence surface charge, if positive, takes place under 

 the influence of attraction from without and repulsion 

 from within ; but, if negative, under the influence of 

 repulsion from without. 



In either case the air is the dielectric between the 

 electrified sphere and surrounding bodies : and when 

 the charge on the sphere is positive, a negative charge 

 of corresponding amount is induced on adjacent parts 

 of surrounding bodies ; electricity being repelled from 

 them by the higher potential of the sphere. But when 

 the charge on the sphere is negative, the charge on 

 adjacent parts of surrounding bodies is positive ; elec- 

 tricity being attracted to them by the lower potential 

 of the sphere. 



Now since surrounding bodies, as a whole, are at 

 zero, and this positive charge, in their adjacent parts, 

 results from the negative attraction of the sphere, it 

 is evident that the interior potential of the sphere, as a 

 whole, cannot rise above zero; the negative potential 

 of its surface being exactly equal to the positive of 

 adjacent parts of surrounding bodies, just as their 

 negative potential was equal to the sphere's positive 

 surface potential in the first instance. Now, since a 

 solid of any conceivable shape could be cut from such a 



