A type of rare gas. Used as a shielding gas for arc welding (cutting) stainless steel, magnesium, aluminum, and other alloys. Also used in the smelting of steel, aluminum, titanium and zirconium. Argon emits a purple glow during discharge, and is used for lighting technology and filling of fluorescent lamps, electric bulbs, photocell preparation or sources: argon-containing fractions can be withdrawn from an air fractionation column, and argon is used to make crude argon, followed by chemical reaction and physical adsorption. The method separates pure argon.