The amount of charge in each jar was determined by bringing a proof-plane into contact with its knob and measuring by a torsion balance the charge taken away.

He first charged one of his instruments, and then dividing the charge with the other, found that when air intervened in both cases the charge was equally divided.

But when shellac, sulphur, or spermaceti was interposed between the two spheres of one jar, while air occupied this interval in the other, then he found that the instrument occupied by the 'solid dielectric' takes more than half the original charge.

A portion of the charge was absorbed by the dielectric itself.

The electricity took time to penetrate the dielectric.