Part 950

Hy*drau"li*con (?), n. [NL. See Hydraulic.] (Mus.) An ancient musical instrument played by the action of water; a water organ. [Written also hydraulis.]

Hy*drau"lics (?), n. [Cf. F. hydraulique.] That branch of science, or of engineering, which treats of fluids in motion, especially of water, its action in rivers and canals, the works and machinery for conducting or raising it, its use as a prime mover, and the like.

As a science, hydraulics includes hydrodynamics, or the principles of mechanics applicable to the motion of water; as a branch of engineering, it consists in the practical application of the mechanics of fluids to the control and management of water with reference to the wants of man, including canals, waterworks, hydraulic machines, pumps, water wheels, etc. Some writers treat hydraulics and hydrostatics as subdivisions of hydrodynamics.

Hy"dra*zine (?), n. [Hydr- + azo- + -ine.] (Chem.) Any one of a series of nitrogenous bases, resembling the amines and produced by the reduction of certain nitroso and diazo compounds; as, methyl hydrazine, phenyl hydrazine, etc. They are derivatives of hydrazine proper, H2N.NH2, which is a doubled amido group, recently (1887) isolated as a stable, colorless gas, with a peculiar, irritating odor. As a base it forms distinct salts. Called also diamide, amidogen, (or more properly diamidogen), etc.

Hy"dren*ceph"s*loid (?), a. [Hydrencephalus + -oid.] (Med.) Same as Hydrocephaloid.

||Hy"dri*a (?), n. [L., fr. Gr. &?;.] (Gr. Antiq.) A water jar; esp., ||one with a large rounded body, a small neck, and three handles. Some ||of the most beautiful Greek vases are of this form.

Hy"dri*ad (?), n. [Gr. &?;, &?;, of the water, fr. "y`dwr water.] (Myth.) A water nymph.

Hy"dric (?), a. [From Hydrogen.] (Chem.) Pertaining to, or containing, hydrogen; as, hydric oxide.

Hydric dioxide. (Chem.) See Hydrogen dioxide, under Hydrogen. -- Hydric oxide (Chem.), water. -- Hydric sulphate (Chem.), hydrogen sulphate or sulphuric acid.

Hy"dride (?), n. [Hydr- + ide.] (Chem.) A compound of the binary type, in which hydrogen is united with some other element.

Hy"dri*form (?), a. [Hydra + -form.] (Zoˆl.) Having the form or structure of a hydra.

||Hy*dri"na (?), n. pl. [NL. See Hydra.] (Zoˆl.) The group of hydroids ||to which the fresh-water hydras belong.

Hy*dri"o*date (?), n. [Cf. F. hydriodate.] (Zoˆl.) Same as Hydriodide.

Hy`dri*od"ic (?), a. [Hydr- + iodic: cf. F. hydriodique.] (Chem.) Pertaining to, or derived from, hydrogen and iodine; -- said of an acid produced by the combination of these elements.

Hydriodic acid (Chem.), a pungent, colorless gas, HI, usually prepared as a solution in water. It is strong reducing agent. Called also hydrogen iodide.

Hy*dri"o*dide (?), n. (Chem.) A compound of hydriodic acid with a base; -- distinguished from an iodide, in which only the iodine combines with the base.

{ Hy"dro- (?), Hy"dr-. } 1. A combining form from Gr. &?;, &?;, water (see Hydra).

2. (Chem.) A combining form of hydrogen, indicating hydrogen as an ingredient, as hydrochloric; or a reduction product obtained by hydrogen, as hydroquinone.

Hy`dro*ba*rom"e*ter (?), n. [Hydro- , 1 + barometer.] An instrument for determining the depth of the sea water by its pressure.

Hy`dro*bil`i*ru"bin (?), n. [Hydro- , 2 + bilirubin.] (Physiol. Chem.) A body formed from bilirubin, identical with urobilin.

||Hy`dro*bran`chi*a"ta (?), n. pl. [NL., fr. Gr. "y`dwr water + &?; ||gills.] (Zoˆl.) An extensive artificial division of gastropod ||mollusks, including those that breathe by gills, as contrasted with ||the Pulmonifera. -- Hy`dro*bran"chi*ate (#), a.

Hy`dro*bro"mate (?), n. (Chem.) Same as Hydrobromide.

Hy`dro*bro"mic (?), a. [Hydro-, 2 + bromic.] (Chem.) Composed of hydrogen and bromine; as, hydrobromic acid.

Hydrobromic acid (Chem.), a colorless, pungent, corrosive gas, HBr, usually collected as a solution in water. It resembles hydrochloric acid, but is weaker and less stable. Called also hydrogen bromide.

Hy`dro*bro"mide (?), n. (Chem.) A compound of hydrobromic acid with a base; -- distinguished from a bromide, in which only the bromine unites with the base.

Hy`dro*car"bon (?), n. [Hydro-, 2 + carbon.] (Chem.) A compound containing only hydrogen and carbon, as methane, benzene, etc.; also, by extension, any of their derivatives.

Hydrocarbon burner, furnace, stove, a burner, furnace, or stove with which liquid fuel, as petroleum, is used.

Hy`dro*car`bo*na"ceous (?), a. Of the nature, or containing, hydrocarbons.