Dry Ice Freon acetylene ammonia argon asphyxiating gas butane carbon monoxide chlorine coal gas coolant ethane ether ethyl chloride ethylene fluorine formaldehyde freezing mixture helium hydrogen ice ice cubes illuminating gas krypton lewisite liquid air liquid helium liquid oxygen marsh gas methane mustard gas natural gas neon nitrogen oxygen ozone poison gas propane radon refrigerant sewer gas xenon