Silicate

(sil'e-kat.) (Chem.) See SILICA. Silicon, (sil'e-kon,) or SILICIUM. [See SILICA.] (Chem.) An element which forms the basis of silica. It is obtained in the free state with great difficulty. At. weight 21; Symbol Si. It exists in three different conditions: 1. Amorphous, as a dull brown powder, insoluble in water; 2. Graph i to i dal, obtained by heating amorphous silicon to a high temperature out of contact with air. Wohler has obtained it by another proce in crystals; 3. Crystalline, or adamantine, in which state it has the form of long needle-shaped crystals, having a dark iron-gray color, and exhibiting iridescence like that of iron glance. At a temperature near the melting point of cast-iron, S. melts, and maybe cast in a mould; the castings have a brilliant surface, and are not altered by exposure to the air. S. forms three oxides, only one. of which is anhydrous; this is the di-oxide or SILICA, q. v. (sil'eek.) [From L. siliqua, a pod.] (Bot.) The long pod-like fruit of Crucifers or Bra icaceæ, consisting of a pair of valves applied to a frame on which the seeds grow. (se-lis'tre-ah,) a fortified city of Turkey in Europe, p. Bulgaria, on the Danube, 63 m. E.N.E. of Rustchuk. This place sustained a memorable siege in 1854, when it was resolutely defended by the Turks under Omer Pasha, who compelled the Ru ians to retire with heavy lo . Pop. 20,000. [s. 826]