336 ALKALINE SALTS.‘ grey and smoke-grey; wine-yellow; sometimes apple- green, sulphur-yellow, and brownish-black. It occurs in efflorescences, crusts, stalaetitic, small bo- tryoidal, tuberose, corroded ; and crystallised in the fol lowing figures: 1. Octahedron. 2. Cube, more or less deeply truncated on the edges. 3. Rectangular four-sided prism, acuminated with four planes, which are set on the lateral planes, or on the lateral edges. 4. Garnet or rhomboidal dodecahedron. 5. Leucite crystallization, or the double eight-sided pyramid, acuminated with four planes. The crystals are small and very small; and their late ral planes are usually smooth. Externally it is dull or glistening; internally shining and vitreous. The fracture is even or uneven, sometimes inclining to fibrous. It sometimes occurs in granular distinct concretions. It alternates from transparent to opaque. It is soft. It is slightly ductile, and elastic. Specific gravity, 1.5442, IlassenJ'ratz. Its taste is pungent and saline. Chemical Characters. When moistened, and rubbed with quicklime, it gives out a pungent ammoniacal odour. Constituent