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.
Hy`dro*log"ic*al (?), a. Of or pertaining to hydrology.
Hy*drol"o*gist (?), n. One skilled in hydrology.
Hy*drol"o*gy (?), n. [Hydro-, 1 + -logy: cf. F. hydrologie.] The
science of water, its properties, phenomena, and distribution over the
earth's surface.
Hy`dro*lyt"ic (?), a. [Hydro-, 1 + Gr. &?; to loose.] (Chem.) 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.
Hy`dro*mag"ne*site (h`dr*mg"n*st), n. [Hydro-, 1 + magnesite.] (Min.) A
hydrous carbonate of magnesia occurring in white, earthy, amorphous
masses.
Hy"dro*man`cy (?), n. [Hydro-, 1 + -mancy: cf. F. hydromancie.]
Divination by means of water, -- practiced by the ancients.
Hy`dro*man"tic (?), a. [Cf. F. hydromantique.] Of or pertaining to
divination by water.
Hy`dro*me*chan"ics (?), n. [Hydro- , 1 + mechanics.] That branch of
physics which treats of the mechanics of liquids, or of their laws of
equilibrium and of motion.
||Hy`dro*me*du"sa (?), n.; pl. HydromedusÊ (#). [NL. See Hydra, and
||Medusa.] (Zoˆl.) Any medusa or jellyfish which is produced by budding
||from a hydroid. They are called also Craspedota, and naked-eyed
||medusÊ.
Such medusÊ 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 medusÊ 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.
Hy"dro*mel (?), n. [L. hydromel, hydromeli, Gr. &?;; &?; water + &?;
honey: cf. F. hydromel.] A liquor consisting of honey diluted in water,
and after fermentation called mead.
Hy`dro*mel*lon"ic (?), a. See Cyamellone.
Hy`dro*met`al*lur"gic*al (?), a. 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, adv.
Hy`dro*met"al*lur`gy (?), n. [Hydro- , 1 + metallurgy.] The art or
process of assaying or reducing ores by means of liquid reagents.
Hy`dro*me"te*or (?), n. [Hydro-, 1 + meteor.] A meteor or atmospheric
phenomenon dependent upon the vapor of water; -- in the pl., a general
term for the whole aqueous phenomena of the atmosphere, as rain, snow,
hail, etc. Nichol.
Hy`dro*me`te*or`o*log"ic*al (?), a. Of or pertaining to
hydrometeorology, or to rain, clouds, storms, etc.
Hy`dro*me`te*or*ol"o*gy (?), n. [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.
Hy*drom"e*ter (?), n. [Hydro-, 1 + -meter: cf. F. hydromËtre.] 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.
{ Hy`dro*met"ric (?), Hy`dro*met"ric*al (?), } a. [Cf. F.
hydromËtrique.] 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.