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Related to Geissler tube: Crookes tube
Geissler tube(gīs`lər), gas discharge tube in which light is produced when an electric discharge passes through the rarefied gas in the tube. The color of the glow depends on the gas used. The tubes are made in a variety of shapes and are especially useful in spectroscopy. One later form of the tube is widely used in luminous signs ("neon" signs) and another in fluorescent lamps.
Geissler tube[′gīs·lər ‚tüb]
An experimental discharge tube with two electrodes at opposite ends, used to demonstrate and study the luminous effects of electric discharges through various gases at low pressures.