(n.) A colorless gaseous substance (O/) obtained (as by the silent discharge of electricity in oxygen) as an allotropic form of oxygen, containing three atoms in the molecule. It is a strong oxidizer, and probably exists in the air, though by he ordinary tests it is liable to be confused with certain other substances, as hydrogen dioxide, or certain oxides of nitrogen. It derives its name from its peculiar odor, which resembles that of weak chlorine.

Dry Ice Freon acetylene argon asphyxiating gas butane carbon dioxide carbon monoxide castor-bean meal chlorine coal gas commercial fertilizer compost coolant dressing dung enrichener ethane ether ethyl chloride ethylene fertilizer fluorine formaldehyde freezing mixture guano helium hydrogen ice ice cubes illuminating gas krypton lewisite liquid air liquid helium liquid oxygen manure marsh gas methane muck mustard gas natural gas neon night soil nitrate nitrogen organic fertilizer oxygen ozone phosphate poison gas propane radon refrigerant sewer gas superphosphate xenon