|
|
Discharge Devices
This classification is for discharge devices - artifacts where electricity is spilled from a wire into the world. In an X-ray tube, electrons are emitted by a cathode, travel through a vacuum while being sped by an electrostatic field, and crash into an anode. At the anode, they emit X-rays. Most sources of ultraviolet light run electricity through a quartz tube filled with mercury vapor, where the hot mercury atoms emit ultraviolet light. (Fluorescent lights have electricity running through a mercury vapor, but they're lined with phosphors that absorb the ultraviolet light and emit visible light. In a tanning booth, they leave out the phosphors and you get a tan from the UV.) The violet ray machine is an early twentieth-century semi-medical device, often found in Grandfather's attic, and usually considered quackery. (I suspect they actually were of some use in dermatology. The story is complicated.) They have a small Tesla coil in the handle, which sends radio-frequency electricity out through a glass tube filled with low-pressure air. These tubes are pressed against the patient's skin. Demonstration devices are often glass tubes filled with glowing gases - the neon sign, the Geissler tube, and the handsome discharge globes found today are in this category. Finally, ozone generators discharge electricity - as ions - into free air at room temperature. These air ions combine chemically to form ozone and nitrogen oxides. Ozone is extremely good at removing other smells from the air, and is a wonderful germ-killer; the benefits of ozone and the perils of ozone have been wrestling back-and-forth in the public mind for almost the entire twentieth century.
|
| The Bakken A Library and Museum of Electricity in Life 3537 Zenith Avenue South Minneapolis, MN 55416-4623, USA Join our E-Mail List Contact Us Tele: 612-926-3878 Fax: 612-927-7265 |
 |
Museum Hours:
Tuesday - Saturday 10 to 5 |