The bell for electroluminescence experiments is used, like the electric egg, to observe, but in more spectacular fashion, how the appearance of electrical discharges in rarefied gases changes with miscellaneousations in pressure and gas.
It consists of a large cylindrical bell of very thick glass (diameter 21 cm, height 31 cm, having the bottom carefully flattened so that it can be placed hermetically on the plate of a pneumatic machine. A brass rod enters the bell through a sturdy brass ring at the centre of the dome. It terminates on the outside with a ring and on the inside with a horizontal electrode in the form of a five-pointed star.
The distance of the points from the centre of the star is 4.5 cm and the overall height of the instrument is 53 cm.