(n.) A gaseous element, colorless, tasteless, and odorless, the lightest known substance, being fourteen and a half times lighter than air (hence its use in filling balloons), and over eleven thousand times lighter than water. It is very abundant, being an ingredient of water and of many other substances, especially those of animal or vegetable origin. It may by produced in many ways, but is chiefly obtained by the action of acids (as sulphuric) on metals, as zinc, iron, etc. It is very inflammable, and is an ingredient of coal gas and water gas. It is standard of chemical equivalents or combining weights, and also of valence, being the typical monad. Symbol H. Atomic weight 1.

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