Rhodium
(Rho"di*um) n. [NL., fr. Gr. "ro`don the rose. So called from the rose-red color of certain
of its solutions. See Rhododendron.] (Chem.) A rare element of the light platinum group. It is found
in platinum ores, and obtained free as a white inert metal which it is very difficult to fuse. Symbol Rh.
Atomic weight 104.1. Specific gravity 12.
Rhodizonic
(Rho`di*zon"ic) a. [Gr. to be rose-red.] (Chem.) Pertaining to, or designating, a colorless
crystalline substance (called rhodizonic acid, and carboxylic acid) obtained from potassium carboxide
and from certain quinones. It forms brilliant red, yellow, and purple salts.
Rhodochrosite
(Rho`do*chro"site) n. [Gr. "ro`don the rose + a coloring.] (Min.) Manganese carbonate,
a rose-red mineral sometimes occuring crystallized, but generally massive with rhombohedral cleavage
like calcite; — called also dialogite.
Rhodocrinite
(Rho*doc"ri*nite) n. [Gr. "ro`don rose + lily.] (Paleon.) A rose encrinite.
Rhododendron
(Rho`do*den"dron) n. [L., fr. Gr. "rodo`dendron, literally, rose tree; "ro`don rose + de`ndron
tree. See Rose.] (Bot.) A genus of shrubs or small trees, often having handsome evergreen leaves,
and remarkable for the beauty of their flowers; rosebay.
Rhodomontade
(Rhod`o*mon*tade") n. See Rodomontade.
Rhodomontader
(Rhod`o*mon*tad"er) n. See Rodomontador.
Rhodonite
(Rho"don*ite) n. [Gr. "ro`don the rose. ] (Min.) Manganese spar, or silicate of manganese,
a mineral occuring crystallised and in rose-red masses. It is often used as an ornamental stone.
Rhodophane
(Rho"do*phane) n. [Gr. "ro`don the rose + to show.] (Physiol.) The red pigment contained
in the inner segments of the cones of the retina in animals. See Chromophane. W. KÜhne.
Rhodopsin
(Rho*dop"sin) n. [Gr. "ro`don rose + "w`ps eye.] (Physiol.) The visual purple. See under
Visual.
Rhodosperm
(Rho"do*sperm) n. [Gr. "ro`don the rose + spe`rma a seed.] (Bot.) Any seaweed with
red spores.
As the name of a subclass, Rhodosperms, or Rhodospermeæ, is synonymous with Florideæ (which see.)
Rhomb
(Rhomb) n. [L. rhombus, Gr. rhomb, a spinning top, magic wheel, fr. to turn or whirl round,
perhaps akin to E. wrench: cf. F. rhombe. Cf. Rhombus, Rhumb.]
1. (Geom.) An equilateral parallelogram, or quadrilateral figure whose sides are equal and the opposite
sides parallel. The angles may be unequal, two being obtuse and two acute, as in the cut, or the angles
may be equal, in which case it is usually called a square.
2. (Geom.) A rhombohedron.
Fresnel's rhomb (Opt.), a rhomb or oblique parallelopiped of crown or St. Gobain glass so cut that
a ray of light entering one of its faces at right angles shall emerge at right angles at the opposite face,
after undergoing within the rhomb, at other faces, two reflections. It is used to produce a ray circularly
polarized from a plane-polarized ray, or the reverse. Nichol.
Rhombic
(Rhom"bic) a.
1. Shaped like a rhomb.
2. (Crystallog.) Same as Orthorhombic.
