a metallic chemical element, symbol Eu, atomic weight 152 0 (0 =16). The oxide Eu 2 0 3 occurs in very small quantity in the minerals of the rare earths, and was first obtained in 1896 by E. A. Demargay from Lecoq de Boisbaudran's samarium; G. Urbain and H. Lacombe in 1904 obtained the pure salts by fractional crystallization of the nitric acid solution with magnesium nitrate in the presence of bismuth nitrate. The salts have a faint pink colour, and show a faint absorption spectrum; the spark spectrum is brilliant and well characterized.