Part 232

Chro`ma*tol"o*gy (?), n. [Gr. &?;, &?;, color + -logy.] A treatise on colors.

Chro"ma*to*phore` (?), n. [Gr. &?;, &?;, color + &?; to bear.] 1. (Zo÷l.) A contractile cell or vesicle containing liquid pigment and capable of changing its form or size, thus causing changes of color in the translucent skin of such animals as possess them. They are highly developed and numerous in the cephalopods.

2. (Bot.) One of the granules of protoplasm, which in mass give color to the part of the plant containing them.

Chro"ma*to*scope` (?), n. [Gr. &?;, &?;, color + -scope.] (Astron.) A reflecting telescope, part of which is made to rotate eccentrically, so as to produce a ringlike image of a star, instead of a point; -- used in studying the scintillation of the stars.

Chro"ma*to*sphere` (?), n. A chromosphere. [R.]

Chro"ma*trope (?), n. [Gr. &?; color + &?; turn, rotation, &?; to turn.] 1. (Physics) An instrument for exhibiting certain chromatic effects of light (depending upon the persistence of vision and mixture of colors) by means of rapidly rotating disks variously colored.

2. A device in a magic lantern or stereopticon to produce kaleidoscopic effects.

Chro"ma*type (?), n. [Gr. &?; color + &?; type.]

1. (Photog.) A colored photographic picture taken upon paper made sensitive with potassium bichromate or some other salt of chromium.

2. The process by which such picture is made.

Chrome (?), n. Same as Chromium.

Chrome alum (Chem.), a dark violet substance, (SO4)3Cr2. K2SO4.24H2O, analogous to, and crystallizing like, common alum. It is regarded as a double sulphate of chromium and potassium. -- Chrome green (a) The green oxide of chromium, Cr2O3, used in enamel painting, and glass staining. (b) A pigment made by mixing chrome yellow with Prussian blue. -- Chrome red, a beautiful red pigment originally prepared from the basic chromate of lead, but now made from red oxide of lead. -- Chrome yellow, a brilliant yellow pigment, PbCrO4, used by painters.

Chro"mic (?), a. (Chem.) Pertaining to, or obtained from, chromium; -- said of the compounds of chromium in which it has its higher valence.

Chromic acid, an acid, H2CrO4, analogous to sulphuric acid, not readily obtained in the free state, but forming well known salts, many of which are colored pigments, as chrome yellow, chrome red, etc. -- Chromic anhydride, a brilliant red crystalline substance, CrO3, regarded as the anhydride of chromic acid. It is one of the most powerful oxidizers known.

Chro"mid (?), n. [Gr. &?; a kind of fish.] (Zo÷l.) One of the ChromidŠ, a family of fresh-water fishes abundant in the tropical parts of America and Africa. Some are valuable food fishes, as the bulti of the Nile.

||Chro`mi*dro"sis (?), n. [NL., fr. Gr. &?; color + &?; sweat.] (Med.) Secretion of abnormally colored perspiration.

Chro"mism (?), n. Same as Chromatism.

Chro"mite (?), n. 1. (Min.) A black submetallic mineral consisting of oxide of chromium and iron; -- called also chromic iron.

2. (Chem.) A compound or salt of chromous hydroxide regarded as an acid. [R.]

Chro"mi*um (?), n. [NL., fr. Gr. &?; color.] (Chem.) A comparatively rare element occurring most abundantly in the mineral chromite. Atomic weight 52.5. Symbol Cr. When isolated it is a hard, brittle, grayish white metal, fusible with difficulty. Its chief commercial importance is for its compounds, as potassium chromate, lead chromate, etc., which are brilliantly colored and are used dyeing and calico printing. Called also chrome.

Chro"mo (?), n.; pl. Chromos (#). [Abbrev. from chromolithograph.] A chromolithograph.

Chro"mo*blast (?), n. [Gr. &?; color + -blast.] An embryonic cell which develops into a pigment cell.

Chro"mo*gen (?), [Gr. &?; color + -gen.]

1. (Biol.) Vegetable coloring matter other than green; chromule.

2. (Chem.) Any colored compound, supposed to contain one or more chromophores.

Chro"mo*gen"ic (?), a. (Biol.) Containing, or capable of forming, chromogen; as, chromogenic bacteria.

Chro"mo*graph (?), n. [Gr. &?; color + -graph.] An apparatus by which a number of copies of written matter, maps, plans, etc., can be made; -- called also hectograph.

Chro`mo*leu"cite (?), n. [Gr. &?; color + E. leucite.] (Bot.) A chromoplastid.