What's in the air you breathe? Most of earth's atmosphere is nitrogen - about 78 percent of it. The next most abundant component is oxygen, at 21 percent. Those two account for 99 percent. What's the third most abundant element in air? You see it every day; mixed with nitrogen, it's used to fill incandescent light bulbs. (Some bulbs are vacuums, but inert gas makes the filament last longer.) The answer: argon. Argon was discovered in the 1890s by William Ramsay, a Scot, who later won the Nobel Prize. He and his co-workers isolated other rare gases in the atmosphere, too: neon, krypton, and xenon. Ramsay was the first to send an electric current through a tube of inert gas, creating the neon light.
Source: 'Strange Universe,' by Bob Berman (Henry Holt, 2003); www.cyberphysics.pwp.blueyonder.co.uk; www.chemheritage.org