Immediately after the discharge of the apparatus, no trace of electricity was found upon its knob.

But after a time electricity was found there, the charge having gradually returned from the dielectric in which it had been lodged.

Different insulators possess this power of permitting the charge to enter them in different degrees.

Faraday figured their particles as polarized, and he concluded that the force of induction is propagated from particle to particle of the dielectric from the inner sphere to the outer one.

This power of propagation possessed by insulators he called their 'Specific Inductive Capacity.' Faraday visualizes with the utmost clearness the state of his contiguous particles; one after another they become charged, each succeeding particle depending for its charge upon its predecessor.