Stone Vintage Radio Museum - Antique Radios, Wireless, Crystal Sets, Tubes, and Valves

Geissler tubes, the name of these electrical discharge tubes, were used late in the 19th and early in the 20th century. Geissler tubes were developed in the late 1850s. Heinrich Geissler was experimenter, researcher and glass blower. Geissler tubes could not be developed until a very good vacuum pump was developed. The effects of electrical discharge is best observed in a glass chamber where the air has been evacuated. The electric charge is produced by an induction coil. 5 volts is increased to several thousand volts in the induction coil. The vacuum in the tube reduces the air molecules and allows electrons to travel farther before they strike something. There is a violet blue light at the negative electrode and a brush discharge at the positive end. A glass tube containing air at normal pressure shows no unusual phenomena; When air is pumped from the tube creating a partial vacuum, the whole geissler tube presents a luminous appearance, a glow of light being exhibited at the negative electrode, while a kind of brush discharge is observed at the positive electrode. They were incited by the use of high voltages created by an induction coil powered by several dry cells. They were named after their inventor. The intensity of the light is greatest in constricted areas. The discharge can be altered by bringing magnets near the geissler tube. Geissler tubes are filled with various gasses at different pressures. 1. Nitrogen causes a pale blue light at the negative pole and a rosy tint at the positive pole. 2. Hydrogen produces a blue light at the negative pole and it becomes crimson in constricted areas. 3. The composition of the glass also affects the color of the discharge. 4. Compound tubes, constructed with an outer jacket filled with a solution of quinine, or a simple tube of uranium glass may be used to create the bluish characteristics of the former and the yellow/green characteristics of the latter. What are they used for? The study of electricity and Parlor entertainments. The box of geissler tubes displayed came from a university in Edinburgh, Scotland. You can tell when it was last used by the newspaper that was used to pack it away: The Scotsman, November 7, 1916. The tubes are judged to be manufactured in about 1890.

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