oxygen

   A colorless, odorless, tasteless, non-explosive gas, it is the most abundant element on earth, constituting about half of the surface material. It makes up about 9/10 of water, two-thirds of the human body, and 1/5 (by volume) of air. Normal atmospheric oxygen is O2. Oxygen forms compounds with almost all of the elements except the inert gases. The common reaction in which it unites with another substance is called oxidation. The burning of substances in air is rapid oxidation, or combustion, oxygen being required for nearly all combustion. Among its chief uses by artists is supporting the combustion of the oxyacetylene torch in welding. Tank sizes available: 20, 40, 80, 122, and 244 cubic feet. Atomic symbol O, atomic number 8. Also see acetylene, argon, carbon dioxide, helium, hydrogen, nitrogen, oxidation firing, and oxide.