Hydroscope Hy"dro·scope noun [ Hydro- , 1 + -scope .] 1. An instrument designed to mark the presence of water, especially in air. Weale.

2. A kind of water clock, used anciently for measuring time, the water tricking from an orifice at the end of a graduated tube.

Hydrosome Hy"dro·some Hy`dro*so"ma noun [ New Latin hydrosoma . See Hydra , and -some body.] (Zoology) All the zooids of a hydroid colony collectively, including the nutritive and reproductive zooids, and often other kinds.

Hydrosorbic Hy`dro·sor"bic adjective [ Hydro- , 2 + sorbic .] (Chemistry) Pertaining to, or designating, an acid obtained from sorbic acid when this takes up hydrogen; as, hydrosorbic acid.

Hydrosphere Hy"dro·sphere noun [ Prefix hydro- , 1 + sphere .] 1. (Meteor.) The aqueous vapor of the entire atmosphere.

2. (Physics Geology) The aqueous envelope of the earth, including the ocean, all lakes, streams, and underground waters, and the aqueous vapor in the atmosphere.

Hydrostat Hy"dro·stat noun A contrivance or apparatus to prevent the explosion of steam boilers.

Hydrostat Hy"dro·stat noun A device, usually electrical, for indicating or regulating the height of water in a reservoir or receptacle.

Hydrostatic, Hydrostatical Hy`dro·stat"ic, Hy`dro·stat"ic·al adjective [ Hydro- , 1 + Greek ... causing to stand: confer French hydrostatique. See Static .] Of or relating to hydrostatics; pertaining to, or in accordance with, the principles of the equilibrium of fluids.

The first discovery made in hydrostatics since the time of Archimedes is due to Stevinus.

Hallam.

Hydrostatic balance , a balance for weighing substances in water, for the purpose of ascertaining their specific gravities. -- Hydrostatic bed , a water bed. -- Hydrostatic bellows , an apparatus consisting of a water-tight bellowslike case with a long, upright tube, into which water may be poured to illustrate the hydrostatic paradox. -- Hydrostatic paradox , the proposition in hydrostatics that any quantity of water, however small, may be made to counterbalance any weight, however great; or the law of the equality of pressure of fluids in all directions. -- Hydrostatic press , a machine in which great force, with slow motion, is communicated to a large plunger by means of water forced into the cylinder in which it moves, by a forcing pump of small diameter, to which the power is applied, the principle involved being the same as in the hydrostatic bellows. Also called hydraulic press , and Bramah press . In the illustration, a is a pump with a small plunger b , which forces the water into the cylinder c , thus driving upward the large plunder d , which performs the reduced work, such as compressing cotton bales, etc.

Hydrostatically Hy`dro·stat"ic·al·ly adverb According to hydrostatics, or to hydrostatic principles. Bentley.

Hydrostatician Hy`dro·sta·ti"cian noun One who is versed or skilled in hydrostatics. [ R.]

Hydrostatics Hy`dro·stat"ics noun [ Confer French hydrostatique .] (Physics) The branch of science which relates to the pressure and equilibrium of nonelastic fluids, as water, mercury, etc.; the principles of statics applied to water and other liquids.

Hydrosulphate Hy`dro·sul"phate noun (Chemistry) Same as Hydrosulphurent .

Hydrosulphide Hy`dro·sul"phide noun (Chemistry) One of a series of compounds, derived from hydrogen sulphide by the replacement of half its hydrogen by a base or basic radical; as, potassium hydrosulphide , KSH. The hydrosulphides are analogous to the hydrates and include the mercaptans.

Hydrosulphite Hy`dro·sul"phite noun (Chemistry) A saline compound of hydrosulphurous acid and a base. [ R.]

Hydrosulphuret Hy`dro·sul"phu·ret noun (Chemistry) A hydrosulphide. [ Archaic]

Hydrosulphureted Hy`dro·sul"phu·ret`ed adjective (Chemistry) Combined with hydrogen sulphide.

Hydrosulphuric Hy`dro·sul·phu"ric adjective [ Hydro- , 2 + sulphuric .] (Chemistry) Pertaining to, or derived from, hydrogen and sulphur; as, hydrosulphuric acid, a designation applied to the solution of hydrogen sulphide in water.

Hydrosulphurous Hy`dro·sul"phur·ous adjective (Chemistry) Pertaining to, or designating, an acid obtained by the reduction of sulphurous acid. See Hyposulphurous acid , under Hyposulphurous .

Hydrotellurate Hy`dro·tel"lu·rate noun (Chemistry) A salt formed by the union of hydrotelluric acid and the base.

Hydrotelluric Hy`dro·tel·lu"ric adjective [ Hydro- , 2 + telluric .] (Chemistry) Formed by hydrogen and tellurium; as, hydrotelluric acid, or hydrogen telluride.

Hydrotheca Hy`dro·the"ca noun ; plural Latin Hydrothecæ , English Hydrothecas . [ New Latin , from English hydra + Greek ... a box.] (Zoology) One of the calicles which, in some Hydroidea (Thecaphora), protect the hydrants. See Illust. of Hydroidea , and Campanularian .

Hydrotherapeutics Hy`dro·ther`a·peu"tics noun [ Hydro- , 1 + therapeutics .] (Medicine) A system of treating disease by baths and mineral waters.

Hydrotherapy Hy`dro·ther"a·py noun [ Hydro- , 1 + therapy .] (Medicine) See Hydropathy .

Hydrothermal Hy`dro·ther"mal adjective [ Hydro- , 1 + thermal .] Of or pertaining to hot water; -- used esp. with reference to the action of heated waters in dissolving, redepositing, and otherwise producing mineral changes within the crust of the globe.

Hydrothorax Hy`dro·tho"rax noun [ Hydro- , 1 + thorax .] (Medicine) An accumulation of serous fluid in the cavity of the chest.

Hydrotic Hy·drot"ic adjective [ Greek "y`dwr water: confer Greek ... moisture, French hydrotique .] Causing a discharge of water or phlegm. -- noun (Medicine) A hydrotic medicine.

Hydrotical Hy·drot"ic·al adjective Hydrotic.

Hydrotrope Hy"dro·trope noun [ Hydro- , 1 + Greek ... to turn, direct.] A device for raising water by the direct action of steam; a pulsometer.

Hydrotropic Hy`dro·trop"ic adjective [ See Hydrotrope .] (Botany) Turning or bending towards moisture, as roots.

Hydrotropism Hy·drot"ro·pism noun (Botany) A tendency towards moisture.

Hydrotropism Hy·drot"ro·pism noun (Botany) In a broader sense, any curvature or turning induced in certain growing plant organs under the influence of moisture.

» When the movement is toward the moisture, as is the case in most roots, the phenomenon is called positive hydrotropism ; when away from the moisture, as in the case of hyphae of certain fungi, negative hydrotropism .

Hydrous Hy"drous adjective [ Greek "y`dwr water.] 1. Containing water; watery.

2. (Chemistry) Containing water of hydration or crystallization.

Hydroxanthane Hy`dro·xan"thane noun (Chemistry) A persulphocyanate. [ Obsolete]

Hydroxanthic Hy`dro·xan"thic adjective [ Hydro- , 2 + xanthic .] (Chemistry) Persulphocyanic.

Hydroxide Hy·drox"ide noun [ Hydro- , 2 + oxide .] (Chemistry) A hydrate; a substance containing hydrogen and oxygen, made by combining water with an oxide, and yielding water by elimination. The hydroxides are regarded as compounds of hydroxyl, united usually with basic element or radical; as, calcium hydroxide ethyl hydroxide .

Hydroxy- Hy·drox"y- (Chemistry) A combining form, also used adjectively, indicating hydroxyl as an ingredient.

Hydroxy acid (Chemistry) , an organic acid, having (besides the hydroxyl group of the carboxyl radical) an alcoholic hydroxyl group, and thus having the qualities of an alcohol in addition to its acid properties; as, lactic and tartaric acids are hydroxy acids.

Hydroxyl Hy·drox"yl noun [ Hydro- , 2 + ox ygen + -yl .] (Chemistry) A compound radical, or unsaturated group, HO, consisting of one atom of hydrogen and one of oxygen. It is a characteristic part of the hydrates, the alcohols, the oxygen acids, etc.

Hydroxylamine Hy·drox`yl·am"ine noun [ Hydroxyl + amine .] (Chemistry) A nitrogenous, organic base, NH ₂ .OH, resembling ammonia, and produced by a modified reduction of nitric acid. It is usually obtained as a volatile, unstable solution in water. It acts as a strong reducing agent.

Hydrozoa Hy`dro·zo"a noun plural [ New Latin , from English hydra + Greek ... an animal.] (Zoology) The Acalephæ; one of the classes of cœlenterates, including the Hydroidea, Discophora, and Siphonophora.

Hydrozoal Hy`dro·zo"al adjective (Zoology) Of or pertaining to the Hydrozoa.

Hydrozoön Hy`dro·zo"ön noun ; plural Latin Hydrozoa , English Hydrozoöns . [ New Latin ] (Zoology) One of the Hydrozoa.

Hydruret Hy"dru·ret noun [ Hydro- , 2] (Chemistry) A binary compound of hydrogen; a hydride. [ Obsolete]

Hydrus Hy"drus noun [ Latin , a water serpent; also, a certain constellation, Greek "y`dros .] (Astron.) A constellation of the southern hemisphere, near the south pole.

Hydræmia Hy·dræ"mi·a (hi*drē"mĭ*ȧ) noun [ New Latin , from Greek "y`dwr water + a"i^ma blood.] (Medicine) An abnormally watery state of the blood; anæmia.

Hye Hye noun & v. See Hie . [ Obsolete] Chaucer.

Hyemal Hy·e"mal adjective [ Latin hyemalis , or better hiemalis , from hyems , hiems , winter: confer French hyémal .] Belonging to winter; done in winter. Sir T. Browne.

Hyemate Hy"e·mate intransitive verb [ Latin hiemare , hiematum . See Hyemal .] To pass the winter. [ Obsolete & R.]

Hyemation Hy`e·ma"tion noun [ Latin hiematio .] 1. The passing of a winter in a particular place; a wintering.

2. The act of affording shelter in winter. [ Obsolete]

Hyen Hy"en noun [ French hyène .] A hyena. [ Obsolete] Shak.

Hyena Hy·e"na noun ; plural Hyenas . [ Latin hyaena , Greek ..., orig., a sow, but usually, a Libyan wild beast, probably , the hyena, from ... hog: confer French hyène . See Sow female hog.] (Zoology) Any carnivorous mammal of the family Hyænidæ , of which three living species are known. They are large and strong, but cowardly. They feed chiefly on carrion, and are nocturnal in their habits. [ Written also hyæna .]

» The striped hyena ( Hyæna striata ) inhabits Southern Asia and a large part of Africa. The brown hyena ( H. brunnea ), and the spotted hyena ( Crocuta maculata ), are found in Southern Africa. The extinct cave hyena ( H. spelæa ) inhabited England and France.

Cave hyena . See under Cave . -- Hyena dog (Zoology) , a South African canine animal ( Lycaon venaticus ), which hunts in packs, chiefly at night. It is smaller than the common wolf, with very large, erect ears, and a bushy tail. Its color is reddish or yellowish brown, blotched with black and white. Called also hunting dog .

Hyetal Hy"e·tal adjective [ Greek ... rain, from ... to rain.] Of or pertaining to rain; descriptive of the distribution of rain, or of rainy regions.

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