A non-explosive, colorless, odorless, tasteless, inert gaseous element used in electric light bulbs, fluorescent tubes, and neon POISONOUS!tubes, and as an inert gas shield in arc welding. Atomic symbol Ar, atomic number 18, atomic weight 39.94, melting point -189.2?C, boiling point -185.7?C. Tank sizes available are 131, 330, and 4754 liquid cubic feet.Also see acetylene, carbon dioxide, helium, hydrogen, nitrogen, and oxygen.