Argon
Argon, AHR gon, is a chemical element that forms 0.94 percent of Earth's atmosphere. Most ordinary light bulbs are filled with argon and a little nitrogen. Argon is also used as a shielding gas in arc welding to protect the metal from oxygen in the air. Lord Rayleigh and Sir William Ramsay discovered it in 1894. See Ramsay, Sir William; Rayleigh, Lord.