As originated by Regnault, it consisted in filling a large glass globe with the gas by alternately exhausting with an air-pump and admitting the pure and dry gas.
Otto von Guericke (1602-1686), the inventor of the air-pump, was burgomaster of Magdeburg.
Lifting B to a sufficient level, turning the cock Geisler's Air-Pump. so as to communicate with the atmosphere and letting the mercury flow into A until it gets to the other side of the stop-cock, which is then placed in the intermediate position.
This can be shown by suspending an electric bell in the receiver of an air-pump, the wires conveying the current passing through an air-tight cork closing the hole at the top of the receiver.
He was the first to employ mercury for the air-pump, and devised a method of determining longitude at sea by observations of the moon among the stars.