containing neon, which was first displayed by Ramsay and Travers; "Ne" is the
symbol for neon, one of the chemical elements. |alt=Photograph of glass tube that's been bent to form the connected letters "Ne". The tube is glowing brightly with a red color.
Neon is a
noble gas chemical element and an
inert gas that is a minor component of the Earth's atmosphere. It was discovered in 1898 by the British scientists
William Ramsay and
Morris W. Travers. When Ramsay and Travers had succeeded in obtaining pure neon from the atmosphere, they explored its properties using an
"electrical gas-discharge" tube that was similar to the tubes used today for neon signs. Travers later wrote, "the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget." The procedure of examining the colors of the light emitted from gas-discharge (or "Geissler" tubes) was well known at the time, since the colors of light (the "spectral lines") emitted by a gas discharge tube are, effectively, fingerprints that identify the gases inside. Immediately following neon's discovery, neon tubes were used as scientific instruments and novelties. However, the scarcity of purified neon gas precluded its prompt application for electrical gas-discharge lighting along the lines of
Moore tubes, which used more common
nitrogen or
carbon dioxide as the working gas, and enjoyed some commercial success in the US in the early 1900s. After 1902,
Georges Claude's company in France,
Air Liquide, began producing industrial quantities of neon as a byproduct of the air liquefaction business. From December 3 to 18, 1910, Claude demonstrated two large ( long), bright red neon tubes at the
Paris Motor Show. |alt=Photograph of a large painted sign in the form of a cowboy. The cowboy is winking his eye. His left hand is lifted, and he's pointing that thumb towards the building to his right. A lighted cigarette dangles from the corner of his mouth. He's wearing a cowboy hat, boots, and a scarf. Glowing neon tubes highlight the outlines. These neon tubes were essentially in their contemporary form. The outer diameters for the glass tubing used in neon lighting ranges from 9 to 25 mm; with standard electrical equipment, the tubes can be as long as . The pressure of the gas inside ranges from 3 to 20
Torr (0.4–3 kPa), which corresponds to a partial vacuum in the tubing. Claude had also solved two technical problems that substantially shortened the working life of neon and some other gas discharge tubes, and effectively gave birth to a neon lighting industry. In 1915, a US patent was issued to Claude covering the design of the electrodes for gas-discharge lighting; this patent became the basis for the monopoly held in the US by his company, Claude Neon Lights, for neon signs through the early 1930s. Claude's patents envisioned the use of gases such as
argon and
mercury vapor to create different colors beyond those produced by neon. For instance, mixing metallic mercury with neon gas creates blue. Green can then be achieved using uranium (yellow) glass. White and gold can also be created by adding argon and
helium. In the 1920s, fluorescent glasses and coatings were developed to further expand the range of colors and effects for tubes with argon gas or argon-neon mixtures; generally, the fluorescent coatings are used with an argon/mercury-vapor mixture, which emits
ultraviolet light that activates the fluorescent coatings. A Smithsonian Institution website notes, "These small, low power devices use a physical principle called 'coronal discharge'." Moore mounted two electrodes close together in a bulb and added neon or argon gas. The electrodes would glow brightly in red or blue, depending on the gas, and the lamps lasted for years. Since the electrodes could take almost any shape imaginable, a popular application has been fanciful decorative lamps. Glow lamps found practical use as electronic components, and as indicators in instrument panels and in many home appliances until the acceptance of light-emitting diodes (LEDs) starting in the 1970s." Although some neon lamps themselves are now antiques, and their use in electronics has declined markedly, the technology has continued to develop in artistic and entertainment contexts. Neon lighting technology has been reshaped from long tubes into thin flat panels used for
plasma displays and plasma television sets. ==Neon tube lighting and signs==