If then the ball be withdrawn, the leaves will diverge a second time with negative electrification.
Clerk Maxwell demonstrated, however, that all electric charge or electrification of conductors consists simply in the establishment of a physical state in the surrounding insulator or dielectric, which state is variously called electric strain, electric displacement or electric polarization.
The reader should, however, notice that what is generally called electric force is the analogue in electricity of the so-called acceleration of gravity in mechanics, whilst electrification or quantity_of electricity is analogous to mass.
This harmonizes with the fact that the real seat of the energy 3f electrification is the dielectric or insulator surrounding the charged conductor.'
By the surface density of electrification on a conductor is meant the charge per unit of area, or the number of tubes of electric force which spring from unit area of its surface.