Volta the electrifying physicist

2. The condenser
In 1782 Volta produced an instrument capable of revealing much weaker amounts of electricity than the then available electroscopes could. He therefore called it the microelectroscope or the condenser of electricity.
The apparatus basically consisted of two conducting discs separated by a thin insulating layer. The charged conductor and the upper plate are put in contact while one finger touches the other conductor. Breaking the contact, the upper plate is raised and its electrical charge is verified with the electroscope, even if the conductor alone cannot show signs of electricity.

             Volta's original condenser and electrometer