1911 Encyclopædia Britannica/Samarium

SAMARIUM [symbol Sm, atomic weight 150.4 (O=16)], a rare earth metal (see Rare Earths). The separation has been worked at by A. V. Welsbach, L. de Boisbaudran, Urbain and Lacombe (Complex rendus, 1903, 137, pp. 568, 792); Demarcay (ibid. 1900, 130, p. 1019); Benedicks; Feit and Przibylla (Zeit. anorg. Chem., 1905, 43, p. 202) and others. The metal may be obtained by reduction of its oxide with magnesium. It combines with hydrogen to form a hydride. The salts are mostly of yellowish colour. The chloride, SmCl₃·6H₂O, is a deliquescent solid which when heated in hydrochloric acid gas to 180° C. yields the anhydrous chloride. This anhydrous chloride is reduced to a lower chloride, of composition SmCl₂, when heated to a high temperature in a current of hydrogen or ammonia (Matignon and Cazes, Comptes rendus, 1906, 142, p. 183). The chloride, SmCl₂, is a brown crystalline powder which is decomposed by water with liberation of hydrogen and the formation of the oxide, Sm₂O₃, and an oxychloride, SmOCl. The fluoride, SmF₃·H₂O, was prepared by H. Moissan by acting with fluorine on the carbide. The sulphate, Sm₂(SO₄)₃·8H₂O, is obtained by the action of sulphuric acid on the nitrate. It forms double salts with the alkaline sulphates. The carbide, SmC₂, is formed when the oxide is heated with carbon in the electric furnace.