A triclinic form is claimed to be obtained by Friedel (Bull.
Again, the pyroxenes, RS103 (R=Fe, Mg, Mn, &c.), assume the forms (I) monoclinic, sometimes twinned so as to become pseudo-rhombic; (2) rhombic, resulting from the pseudo-rhombic structure of (I) becoming ultramicroscopic; and (3) triclinic, distinctly different from (I) and (2); (I) and (2) are polysymmetric modifications, while (3) and the pair (I) and (2) are polymorphs.
Hexachlorethane is trimorphous, forming rhombic, triclinic and cubic crystals; the successive changes occur at about 44° and 71°, and are attended by a decrease in density.
Thus, for instance, near Nikko in the upper valley of the Daiya-gawa, and in several other places in the neighboring mountains, a granite-porphyry appears with large, pale, flesh-colored crystals of orthoclase, dull triclinic feispar, quartz and hornblende.
Boric acid crystallizes from water in white nacreous laminae belonging to the triclinic system; it is difficultly soluble in cold water, but dissolves readily in hot water.
If this be dissolved in water and the solution concentrated, some silicic acid separates and the filtrate deposits triclinic prisms of tungstosilicic acid.
Van Deventer, ibid., 1906, 3, p. 515.) It crystallizes with five molecules of water as large blue triclinic prisms. When heated to Poo°, it loses four molecules of water and forms the bluish-white monohydrate, which, on further heating to 250°-260°, is converted into the white CuSO 4.
Silver nitrate, AgNO 3, one of the most important silver salts, is obtained by dissolving the metal in moderately dilute nitric acid; on evaporation it separates in the anhydrous form as colourless triclinic plates.
Ferrous sulphate forms large green crystals belonging to the monoclinic system; rhombic crystals, isomorphous with zinc sulphate, are obtained by inoculating a solution with a crystal of zinc sulphate, and triclinic crystals of the formula FeSO 4.5H 2 O by inoculating with copper sulphate.
It forms large triclinic prisms of specific gravity 2.6-2.7, which are moderately soluble in cold water and readily soluble in hot water.