Hy"dro*gen (?), n.
[Hydro-, 1 + -gen: cf. F. hydrogène. So called because water is generated by its combustion. See Hydra.]
(Chem.) 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.
&fist; Although a gas, hydrogen is chemically similar to the metals in
its nature, having the properties of a weak base. It is, in all acids, the base which is replaced by metals and basic radicals to form salts. Like all other gases, it is condensed by
great cold and pressure to a liquid which freezes and solidifies by its own evaporation. It is absorbed in large quantities by certain metals (esp. palladium), forming alloy-like compounds; hence, in view of quasi-metallic nature, it is
sometimes called hydrogenium. It is the typical reducing agent, as opposed to oxidizers, as oxygen, chlorine, etc.
Bicarbureted hydrogen, an old name for
ethylene. -- Carbureted hydrogen gas. See under Carbureted. -- Hydrogen dioxide,
a thick, colorless liquid, H2O2, resembling
water, but having a bitter, sour taste, produced by the action of
acids on barium peroxide. It decomposes into water and oxygen, and is manufactured in large quantities for an oxidizing and bleaching agent. Called also oxygenated
water. -- Hydrogen oxide, a chemical name for water, H&?;O. -- Hydrogen sulphide, a colorless inflammable
gas, H2S, having the
characteristic odor
of bad eggs, and found in
many mineral springs. It is produced by
the action of acids on metallic sulphides, and is an important chemical reagent. Called also sulphureted hydrogen.
Hear it pronounced