Part 385

{ Ir`i*da"ceous (?), I*rid"e*ous (?), } a. [From NL. Iris, Iridis, the Iris.] (Bot.) Pertaining to, or resembling, a large natural order of endogenous plants (Iridaceæ), which includes the genera Iris, Ixia, Crocus, Gladiolus, and many others.

I"ri*dal (?; 277), a. [L. iris, iridis, rainbow. See Iris.] Of or pertaining to the iris or rainbow; prismatic; as, the iridal colors. Whewell.

Ir`i*dec"to*my (?), n. [Gr. &?;, &?;, iris + &?; cutting out; &?; out + te`mnein to cut.] (Surg.) The act or process of cutting out a portion of the iris in order to form an artificial pupil.

Ir`i*des"cence (?), n. [See Iridescent.] Exhibition of colors like those of the rainbow; the quality or state of being iridescent; a prismatic play of color; as, the iridescence of mother-of-pearl.

Ir`i*des"cent (?; 277), a. [L. iris, iridis, the rainbow: cf. F. iridescent.] Having colors like the rainbow; exhibiting a play of changeable colors; nacreous; prismatic; as, iridescent glass.

I*rid"i*an (?), a. Of or pertaining to the iris or rainbow.

I*rid"i*a`ted (?), a. Iridescent.

I*rid"ic (?), a. Of or pertaining to the iris of the eye.

I*rid"ic, a. (Chem.) Of or pertaining to iridium; -- said specifically of those compounds in which iridium has a relatively high valence.

I*rid"i*o*scope (?), n. [See Iris, and -scope.] A kind of ophthalmoscope.

I*rid"i*ous (*rd"*s), a. (Chem.) Of or pertaining to iridium; -- applied specifically to compounds in which iridium has a low valence.

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I*rid"i*um (*rd"*m), n. [NL., fr. L. iris, iridis, the rainbow. So called from the iridescence of some of its solutions. See Iris.] (Chem.) A rare metallic element, of the same group as platinum, which it much resembles, being silver-white, but harder, and brittle, and indifferent to most corrosive agents. With the exception of osmium, it is the heaviest substance known, its specific gravity being 22.4. Symbol Ir. Atomic weight 192.5.

Iridium usually occurs as a native alloy with osmium (iridosmine or osmiridium), which may occur alone or with platinum. Iridium, as an alloy with platinum, is used in bushing the vents of heavy ordnance. It is also used for the points of gold pens, and in a finely powdered condition (iridium black), for painting porcelain black.

Ir"i*dize (?), v. t. [imp. & p. p. Iridized (?); p. pr. & vb. n. Iridizing (?).]

1. To point or tip with iridium, as a gold pen.

2. To make iridescent; as, to iridize glass.

I*rid"o*line (?), n. [Iridescent + L. oleum oil.] (Chem.) A nitrogenous base C10H9N, extracted from coal-tar naphtha, as an oily liquid. It is a member of the quinoline series, and is probably identical with lepidine.

{ Ir`i*dos"mine (?), Ir`i*dos"mi*um (?), } n. [Iridium + osmium.] (Min.) The native compound of iridium and osmium. It is found in flattened metallic grains of extreme hardness, and is often used for pointing gold pens.

I"ris (?), n.; pl. E. Irises (#), L. Irides (#). [L. iris, iridis, the goddess, Gr. &?;, &?;, the rainbow, iris of the eye, the plant Iris. Cf. Orris.] 1. (Class. Myth.) The goddess of the rainbow, and swift-footed messenger of the gods. Shak.

2. The rainbow. Sir T. Browne.

3. An appearance resembling the rainbow; a prismatic play of colors. Tennyson.

4. (Anat.) The contractile membrane perforated by the pupil, and forming the colored portion of the eye. See Eye.

5. (Bot.) A genus of plants having showy flowers and bulbous or tuberous roots, of which the flower-de- luce (fleur-de-lis), orris, and other species of flag are examples. See Illust. of Flower-de-luce.

6. (Her.) See Fleur-de-lis, 2.

I"ris*a`ted (?), a. [See Iris.] Exhibiting the prismatic colors; irised; iridescent. W. Phillips.

I"ri*scope (?), n. [Iris + - scope.] A philosophical toy for exhibiting the prismatic tints by means of thin films.

I"rised (?), a. [See Iris.] Having colors like those of the rainbow; iridescent. Holmes.