lan than am, lantanium, lantane

[ Gr.lanthanō =to lie hid.] Chem.: A metallic diad element, symbol La", atomic weight, 9018; discovered by Mosander. It occurs along with didymium and cerium (q. v.) in the mineral cerite, from which it may be separated as an oxide, by the method described under didymium. To obtain the pure metal, the anhydrous chloride is decomposed with sodium, and the chloride of sodium di olved out with absolute alcohol. It is a dark, lead-gray powder, soft to the touch. and adhering when pre ed. Lanthanum appears to form only one set of compounds, and its salts are mostly colorle , their solutions yielding, with alkalies, a precipitate of lanthanum hydrate, LaO1H2O, which, when ignited, leaves the white anhydrous monoxide. Lanthanum chloride, LaCl, forms a radio-crystalline ma soluble in alcohol. Lanthanum oxy-chloride, LagCl2O3, is a white powder insoluble in water, but soluble in hydrochloric and nitric acids. Lanthanum sulphide, La2S, crystallizes in microscopic crystals of a bright yellow color. Lanthanum sulphate forms small prismatic crystals containing LaSO43H2O.