Hydrogen
HY'DROGEN, noun [Gr. water, and to generate; so called as being considered the generator of water.]
In Chimistry, a gas which constitutes one of the elements of water, of which it is said by Lavoisier to form fifteen parts in a hundred; but according to Berzelius and Dulong, hydrogen gas is 11.1 parts in a hundred, and oxygen 88.9. hydrogen gas is an aeriform fluid, the lightest body known, and though extremely inflammable itself, it extinguishes burning bodies, and is fatal to animal life. Its specific gravity is 0.0694, that of air being 1.00. In consequence of its extreme lightness, it is employed for filling air balloons.