polychresty (polikresti)

[ Buck's Handbook of Med. Sciences, VIII. 518. polychroic (pol-i-krō'ik), a. Same as pleochroic. Optical properties of the polychroic aureolas present in certain minerals, by M. A. Michel Lévy. Nature , XLI. 215. polychroism (pol'i-kro-izm), n. [= F. poly chroïsme; chroisme; many many, + χροιά, color.] Same as pleochroism. polychroite (pol-i-krō'īt), n. [=F. F. polychroïte, polychro πολύχρους , many-colored (see polychroism ), -ite2 .] The coloring matter of saffron: so named in consequence of the variety of colors which it exhibits when acted upon by various reagents. polychromatic (pol i-kro-mat'ik), a. [ chromatic light. 2. In mineral., exhibiting a play of colors. — Polychromatic acid. See polychro mic acid, under polychromic. Polychromatic proce , a carbon photographic proce invented by Vidal, analogous to chromolithography in method and object. The first step is to make from the subject as many negatives polychromatic as there are colors to be represented, each of these being appropriated for particular tint, while all wise tinted in the original are masked on the negative with an opaque pigment. Gelatin pictures of the required tints are then prepared from the negatives, and superimposed in turn by a system of registration over a print of the whole subject previously made with a neutral ground, thus completing polychromatic picture. This proce gives strikingly naturalistic results in the reproduction of goldsmiths' work, enamels, mosaics, etc. polychrome (pol'i-krōm), a. and n. [F. polychrome; A large panorama of Pergamon, exhibited in con reconstruction of the eastern front of the Olympian junction with a full-size plastic restoration and polychrome ple. Tenth Report of the Archæol. Institute of America, [1888-9, p. 55. Polychrome printing, the art or proce of printing in several colors at the same time. II. n. A fluorescent substance (C21H24013), forming prismatic crystals, odorle , with a bitter taste and slight acid reaction. It is obtained from the bark of the horse-chestnut and from qua ia wood, etc. A solution of polychrome appears colorle by transmitted light, but blue by reflected light. Acids destroy the fluorescence of the liquid; alkalis increase it. polychromic (pol-i-krō'mik), a . [ polychrome tion of nitric acid upon aloes.