Part 952

Hy`dro*fer`ro*cy*an"ic (?), a. [Hydro-, 2 + ferrocyanic.] (Chem.) Pertaining to, or containing, or obtained from, hydrogen, ferrous iron, and cyanogen; as, hydroferrocyanic acid. See Ferrocyanic.

Hy`dro*flu"ate (?), n. (Chem.) A supposed compound of hydrofluoris acid and a base; a fluoride. [Archaic]

Hy`dro*flu*or"ic (?), a. [Hydro- , 2 + fluoric.] (Chem.) Pertaining to, or containing, hydrogen and fluorine; fluohydric; as, hydrofluoric acid.

Hydrofluoric acid (Chem.), a colorless, mobile, volatile liquid, HF, very corrosive in its action, and having a strong, pungent, suffocating odor. It is produced by the action of sulphuric acid on fluorite, and is usually collected as a solution in water. It attacks all silicates, as glass or porcelain, is the agent employed in etching glass, and is preserved only in vessels of platinum, lead, caoutchouc, or gutta-percha.

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Hy`dro*flu`o*sil"i*cate (?), n. (Chem.) A salt of hydrofluosilic acid; a silicofluoride. See Silicofluoride.

Hy`dro*flu`o*si*lic"ic (?), a. [Hydro-, 2 + fluorine + silicic.] (Chem.) Pertaining to, or denoting, a compound consisting of a double fluoride of hydrogen and silicon; silicofluoric. See Silicofluoric.

Hy`dro*gal*van"ic (?), a. [Hydro- , 1 + galvanic.] Pertaining to, produced by, or consisting of, electricity evolved by the action or use of fluids; as, hydrogalvanic currents. [R.]

Hy"dro*gen (?), n. [Hydro-, 1 + -gen: cf. F. hydrogËne. 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.

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.

Hy"dro*gen*ate (?), v. t. [imp. & p. p. Hydrogenated (?); p. pr. & vb. n. Hydrogenating (?).] (Chem.) To hydrogenize.

Hy`dro*gen*a"tion (?), n. (Chem.) The act of combining with hydrogen, or the state of being so combined.

Hy"dro*gen*ide (?), n. (Chem.) A binary compound containing hydrogen; a hydride. [R.] See Hydride.

Hy`dro*ge"ni*um (?), n. [NL. See Hydrogen.] (Chem.) Hydrogen; -- called also in view of its supposed metallic nature. Graham.

Hy"dro*gen*ize (?), v. t. [imp. & p. p. Hydrogenized (?); p. pr. & vb. n. Hydrogenizing (?).] (Chem.) To combine with hydrogen; to treat with, or subject to the action of, hydrogen; to reduce; -- contrasted with oxidize.

Hy*drog"e*nous (?), a. Of or pertaining to hydrogen; containing hydrogen.

Hy*drog"no*sy (?), n. [Hydro-, 1 + Gr. &?; knowledge.] A treatise upon, or a history and description of, the water of the earth.

Hy"drog*ode (?), n. [Hydrogen + Gr. &?; way. path.] (Elec.) The negative pole or cathode. [R.]

Hy*drog"ra*pher (?), n. One skilled in the hydrography; one who surveys, or draws maps or charts of, the sea, lakes, or other waters, with the adjacent shores; one who describes the sea or other waters. Boyle.

{ Hy`dro*graph"ic (?), Hy`dro*graph"ic*al (?), } a. Of or relating to hydrography.

Hy*drog"ra*phy (?), n. [Hydro-, 1 + -graphy: cf. F. hydrographie.] 1. The art of measuring and describing the sea, lakes, rivers, and other waters, with their phenomena.

2. That branch of surveying which embraces the determination of the contour of the bottom of a harbor or other sheet of water, the depth of soundings, the position of channels and shoals, with the construction of charts exhibiting these particulars.

Hy*drog"u*ret (?), n. [From Hydrogen.] (Chem.) A hydride. [Obs.]

Hy"droid (?), a. [Hydra + - oid.] (Zoˆl.) Related to, or resembling, the hydra; of or pertaining to the Hydroidea. -- n. One of the Hydroideas.

||Hy*droi"de*a, n. pl. [NL. See Hydra, and -oid.] (Zoˆl.) An extensive ||order of Hydrozoa or AcalephÊ. [Written also Hydroida.]

This order includes the hydras and the free-swimming hydromedusÊ, together with a great variety of marine attached hydroids, many of which grow up into large, elegantly branched forms, consisting of a vast number of zooids (hydranths, gonophores, etc.), united by hollow stems. All the zooids of a colony are produced from one primary zooid, by successive buddings. The Siphonophora have also been included in this order by some writers. See Gymnoblastea, Hydromedusa, Gonosome, Gonotheca.

Hy`dro*ki*net"ic (?), a. [Hydro- , 1 + kinetic.] Of or pertaining to the motions of fluids, or the forces which produce or affect such motions; -- opposed to hydrostatic. Sir W. Thomson.