Hydrogen ::
Hydrogen (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