The electroscope was used in conjunction with an oil lamp or gas flame.
The sign of the electrification imparted to the electroscope when so charged - that is, whether positive or negative - can be determined by rubbing the sealing-wax rod with flannel and the glass rod with silk, and approaching them gently to the electroscope one at a time.
If an insulated brass ball is touched against the first tray and then against the knob or plate of the electroscope, the gold leaves will diverge.
If the ball is discharged and touched against the other tray, and then afterwards against the previously charged electroscope, the leaves will collapse.
The next improvement was the invention of simple forms of repulsion electroscope.