Hydrated to Hydroidea
(Hy"dra*ted) a. Formed into a hydrate; combined with water.
Water of hydration (Chem.), water chemically combined with some substance to form a hydrate;
distinguished from water of crystallization.
(Hy*dra"tion) n. (Chem.) The act of becoming, or state of being, a hydrate.
Hydraulic accumulator, an accumulator for hydraulic machinery of any kind. See Accumulator, 2.
Hydraulic brake, a cataract. See Cataract, 3. Hydraulic cement, a cement or mortar made of
hydraulic lime, which will harden under water. Hydraulic elevator, a lift operated by the weight or
pressure of water. Hydraulic jack. See under Jack. Hydraulic lime, quicklime obtained from
hydraulic limestone, and used for cementing under water, etc. Hydraulic limestone, a limestone
which contains some clay, and which yields a quicklime that will set, or form a firm, strong mass, under
water. Hydraulic main (Gas Works), a horizontal pipe containing water at the bottom into which
the ends of the pipes from the retorts dip, for passing the gas through water in order to remove ammonia.
Hydraulic mining, a system of mining in which the force of a jet of water is used to wash down
a bank of gold-bearing gravel or earth. [Pacific Coast] Hydraulic press, a hydrostatic press. See
under Hydrostatic. Hydraulic propeller, a device for propelling ships by means of a stream of
water ejected under water rearward from the ship. Hydraulic ram, a machine for raising water by
means of the energy of the moving water of which a portion is to be raised. When the rush of water
through the main pipe d shuts the valve at a, the momentum of the current thus suddenly checked
forces part of it into the air chamber b, and up the pipe c, its return being prevented by a valve at the
entrance to the air chamber, while the dropping of the valve a by its own weight allows another rush
through the main pipe, and so on alternately. Hydraulic valve. (Mach.) (a) A valve for regulating
the distribution of water in the cylinders of hydraulic elevators, cranes, etc. (b) (Gas Works) An inverted
cup with a partition dipping into water, for opening or closing communication between two gas mains,
the open ends of which protrude about the water.
(Hy*drau"lic) a. [F. hydraulique, L. hydraulicus, fr. Gr. a water organ; "y`dwr water + flute,
pipe. See Hydra.] Of or pertaining to hydraulics, or to fluids in motion; conveying, or acting by, water; as,
an hydraulic clock, crane, or dock.
(Hy*drau"lic*al) a. Hydraulic.
(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
(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.