DYSPROSIUM is a metallic element belonging to the rare earth group. In 1886 de Boisbaudran deposited a sealed paper with the Academie des Sciences; this was opened at a later date and read at the writer's request. It contained the statement that a new element possessing a characteristic absorption spec trum had been separated from crude holmia. The oxide was ob tained pure for the first time in 1906 by G. Urbain. This element occurs along with erbium, holmium, etc., in the minerals gadolin ite, euxenite, xenotime, etc. Its symbol is Dy, atomic number 66, and atomic weight 162.5. It is best obtained free from its congeners by the fractional crystallization of the bromates. The white oxide dissolves in many acids forming yellowish-green solutions which show a strong absorption spectrum. The salts of this metal possess the highest magnetic susceptibility of all salts. See RARE EARTHS. (C. J.)