Hydrology Hy·drol"o·gy noun [ Hydro- , 1 + -logy : confer French hydrologie .] The science of water, its properties, phenomena, and distribution over the earth's surface.

Hydrolysis Hy·drol"y·sis noun [ Hydro- , 1 + -lysis .] (Chemistry) A chemical process involving the addition of the elements of water.

Hydrolytic Hy`dro·lyt"ic adjective [ Hydro- , 1 + Greek ... to loose.] (Chemistry) Tending to remove or separate water; eliminating water.

Hydrolytic agents, such as sulphuric acid or caustic alkali.

Encyc. Brit.

Hydrolytic ferment (Physiol. Chem.) , a ferment, enzyme, or chemical ferment, which acts only in the presence of water, and which causes the substance acted upon to take up a molecule of water. Thus, diastase of malt, ptyalin of saliva, and boiling dilute sulphuric acid all convert starch by hydration into dextrin and sugar. Nearly all of the digestive ferments are hydrolytic in their action.

Hydromagnesite Hy`dro·mag"ne·site (hī`dro*măg"ne*sīt) noun [ Hydro- , 1 + magnesite .] (Min.) A hydrous carbonate of magnesia occurring in white, earthy, amorphous masses.

Hydromancy Hy"dro·man`cy noun [ Hydro- , 1 + -mancy : confer French hydromancie .] Divination by means of water, -- practiced by the ancients.

Hydromantic Hy`dro·man"tic adjective [ Confer French hydromantique .] Of or pertaining to divination by water.

Hydromechanics Hy`dro·me·chan"ics noun [ Hydro- , 1 + mechanics .] That branch of physics which treats of the mechanics of liquids, or of their laws of equilibrium and of motion.

Hydromedusa Hy`dro·me·du"sa noun ; plural Hydromedusæ . [ New Latin See Hydra , and Medusa .] (Zoology) Any medusa or jellyfish which is produced by budding from a hydroid. They are called also Craspedota , and naked-eyed medusæ .

» Such medusæ are the reproductive zooids or gonophores, either male or female, of the hydroid from which they arise, whether they become free or remain attached to the hydroid colony. They in turn produce the eggs from which the hydroids are developed. The name is also applied to other similar medusæ which are not known to bud from a hydroid colony, and even to some which are known to develop directly from the eggs, but which in structure agree essentially with those produced from hydroids. See Hydroidea , and Gymnoblastea .

Hydromel Hy"dro·mel noun [ Latin hydromel , hydromeli , Greek ...; ... water + ... honey: confer French hydromel .] A liquor consisting of honey diluted in water, and after fermentation called mead .

Hydromellonic Hy`dro·mel·lon"ic adjective See Cyamellone .

Hydrometallurgical Hy`dro·met`al·lur"gic·al adjective Of or pertaining to hydrometallurgy; involving the use of liquid reagents in the treatment or reduction of ores. -- Hy`dro*met`al*lur"gic*al*ly , adverb

Hydrometallurgy Hy`dro·met"al·lur`gy noun [ Hydro- , 1 + metallurgy .] The art or process of assaying or reducing ores by means of liquid reagents.

Hydrometeor Hy`dro·me"te·or noun [ Hydro- , 1 + meteor .] A meteor or atmospheric phenomenon dependent upon the vapor of water; -- in the plural , a general term for the whole aqueous phenomena of the atmosphere, as rain, snow, hail, etc. Nichol.

Hydrometeorological Hy`dro·me`te·or`o·log"ic·al adjective Of or pertaining to hydrometeorology, or to rain, clouds, storms, etc.

Hydrometeorology Hy`dro·me`te·or·ol"o·gy noun [ Hydro- , 1 + meteorology .] That branch of meteorology which relates to, or treats of, water in the atmosphere, or its phenomena, as rain, clouds, snow, hail, storms, etc.

Hydrometer Hy·drom"e·ter noun [ Hydro- , 1 + -meter : confer French hydromètre .] 1. (Physics) An instrument for determining the specific gravities of liquids, and thence the strength spirituous liquors, saline solutions, etc.

» It is usually made of glass with a graduated stem, and indicates the specific gravity of a liquid by the depth to which it sinks in it, the zero of the scale marking the depth to which it sinks in pure water. Extra weights are sometimes used to adapt the scale to liquids of different densities.

2. An instrument, variously constructed, used for measuring the velocity or discharge of water, as in rivers, from reservoirs, etc., and called by various specific names according to its construction or use, as tachometer , rheometer , hydrometer , pendulum , etc.; a current gauge.

Hydrometric, Hydrometrical Hy`dro·met"ric, Hy`dro·met"ric·al adjective [ Confer French hydromètrique .] 1. Of or pertaining to an hydrometer, or to the determination of the specific gravity of fluids.

2. Of or pertaining to measurement of the velocity, discharge, etc., of running water.

3. Made by means of an hydrometer; as, hydrometric observations.

Hydrometric pendulum , a species of hydrometer consisting of a hollow ball of ivory or metal suspended by a treated from the center of a graduated quadrant, and held in a stream to measure the velocity of the water by the inclination given to the thread; a kind of current gauge.

Hydrometrograph Hy`dro·met"ro·graph noun [ Hydro- , 1 + Greek ... measure + -graph .] An instrument for determining and recording the quantity of water discharged from a pipe, orifice, etc., in a given time.

Hydrometry Hy·drom"e·try noun [ Confer French hydromètrique .] 1. The art of determining the specific gravity of liquids, and thence the strength of spirituous liquors, saline solutions, etc.

2. The art or operation of measuring the velocity or discharge of running water, as in rivers, etc.

Hydromica Hy`dro·mi"ca noun [ Hydro- , 1 + mica .] (Min.) A variety of potash mica containing water. It is less elastic than ordinary muscovite.

Hydromica schist (Min.) , a mica schist characterized by the presence of hydromica. It often has a silky luster and almost soapy feel.

Hydronephrosis Hy`dro·ne·phro"sis noun [ New Latin , Greek "y`dwr water + ... a kidney.] (Medicine) An accumulation of urine in the pelvis of the kidney, occasioned by obstruction in the urinary passages.

Hydropath Hy"dro·path noun [ Confer French hydropathe .] A hydropathist.

Hydropathic, Hydropathical Hy`dro·path"ic, Hy`dro·path"ic·al adjective Of or pertaining to hydropathy.

Hydropathist Hy·drop"a·thist noun One who practices hydropathy; a water-cure doctor.

Hydropathy Hy·drop"a·thy noun [ Hydro- , 1 + Greek ..., ..., to suffer.] The water cure; a mode of treating diseases by the copious and frequent use of pure water, both internally and externally.

Hydroperitoneum Hy`dro·per`i·to·ne"um noun [ New Latin See Hydro- , and Peritoneum .] (Medicine) Same as Ascites .

Hydrophane Hy"dro·phane noun [ Hydro- , 1 + Greek ... to show, appear: confer French hydrophane .] (Min.) A semitranslucent variety of opal that becomes translucent or transparent on immersion in water.

Hydrophanous Hy·droph"a·nous adjective (Min.) Made transparent by immersion in water.

Hydrophid Hy"dro·phid noun [ Hydro- , 1 + Greek ... a small serpent.] (Zoology) Any sea snake of the genus Hydrophys and allied genera. These snakes are venomous, live upon fishes, and have a flattened tail for swimming.

Hydrophlorone Hy`dro·phlo"rone noun [ Hydro- , 2 + phlorone .] (Chemistry) A white, crystalline benzene derivative, C ₈ H ₁₀ O ₂ , obtained by the reduction of phlorone.

Hydrophobia Hy`dro·pho"bi·a noun [ Latin , from Greek ...; "y`dwr water + ... fear: confer French hydrophobie .] (Medicine) (a) An abnormal dread of water, said to be a symptom of canine madness; hence: (b) The disease caused by a bite form, or inoculation with the saliva of, a rabid creature, of which the chief symptoms are, a sense of dryness and construction in the throat, causing difficulty in deglutition, and a marked heightening of reflex excitability, producing convulsions whenever the patient attempts to swallow, or is disturbed in any way, as by the sight or sound of water; rabies; canine madness. [ Written also hydrophoby .]

Hydrophobic Hy`dro·phob"ic adjective [ Latin hydrophobicus , Greek ...: confer French hydrophobique .] Of or pertaining to hydrophobia; producing or caused by rabies; as, hydrophobic symptoms; the hydrophobic poison.

Hydrophoby Hy"dro·pho`by noun See Hydrophobia .

Hydrophora Hy·droph"o·ra noun plural [ New Latin , from English hydra + Greek ... to bear.] (Zoology) The Hydroidea.

Hydrophore Hy"dro·phore noun [ Greek "y`dwr water + ... to bear.] An instrument used for the purpose of obtaining specimens of water from any desired depth, as in a river, a lake, or the ocean.

Hydrophyllium Hy`dro·phyl"li·um noun ; plural Latin Hydrophyllia , English Hydrophylliums . [ New Latin , from Greek "y`dwr water + ... a leaf.] (Zoology) One of the flat, leaflike, protective zooids, covering other zooids of certain Siphonophora.

Hydrophyte Hy"dro·phyte noun [ Greek ... + ... plant: confer French hydrophyte .] An aquatic plant; an alga.

Hydrophytology Hy·droph`y·tol"o·gy noun [ Hydro- + phyte + -logy .] The branch of botany which treats of water plants.

Hydropic, Hydropical Hy·drop"ic, Hy·drop"ic·al adjective [ Latin hydropicus , Greek ...: confer French hydropique . See Dropsy .] Dropsical, or resembling dropsy.

Every lust is a kind of hydropic distemper, and the more we drink the more we shall thirst.

Tillotson.

Hydropically Hy·drop"ic·al·ly adverb In a hydropical manner.

Hydropiper Hy"dro·pi`per noun [ New Latin , from Greek "y`dwr water + Latin piper a pepper.] (Botany) A species ( Polygonum Hydropiper ) of knotweed with acrid foliage; water pepper; smartweed.

Hydroplane Hy"dro·plane noun [ Prefix hydro- , 1 + plane .] 1. A plane, or any of a number of planes, projecting from the hull of a submarine boat, which by being elevated or depressed cause the boat, when going ahead, to sink or rise, after the manner of an aëroplane.

2. A projecting plane or fin on a gliding boat to lift the moving boat on top of the water; also, a gliding boat.

Hydroplane Hy"dro·plane intransitive verb Of a boat, to plane (see Plane , below).

Hydropneumatic Hy`dro·pneu·mat"ic adjective [ Hydro- , 1 + pneumatic : confer French hydropneumatique .] Pertaining to, or depending upon, both liquid and gaseous substances; as, hydropneumatic apparatus for collecting gases over water or other liquids.

Hydropneumatic gun carriage Hy`dro·pneu·mat"ic gun carriage (Ordnance) A disappearing gun carriage in which the recoil is checked by cylinders containing liquid and air, the air when compressed furnishing the power for restoring the gun to the firing position. It is used with some English and European heavy guns.

Hydropsy Hy"drop`sy noun Same as Dropsy .

Hydropult Hy"dro·pult noun [ Hydro- , 1 + Greek ... to hurl.] A machine for throwing water by hand power, as a garden engine, a fire extinguisher, etc.

Hydroquinone Hy`dro·qui"none noun [ Hydro- , 2 + quinone .] (Chemistry) A white crystalline substance, C ₆ H ₄ (OH) ₂ , obtained by the reduction of quinone. It is a diacid phenol, resembling, and metameric with, pyrocatechin and resorcin. Called also dihydroxy benzene .

Hydrorhiza Hy`dro·rhi"za noun ; plural Latin Hydrorhizæ , English Hydrorhizas . [ New Latin , from English hydra + Greek ... a root.] (Zoology) The rootstock or decumbent stem by which a hydroid is attached to other objects. See Illust. under Hydroidea .

Hydrosalt Hy"dro·salt` noun [ Hydro- , 1 + salt .] (Chemistry) (a) A salt supposed to be formed by a hydracid and a base. (b) An acid salt. [ R.] (c) A hydrous salt; a salt combined with water of hydration or crystallization.

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