Cerium
a metal (Sym. Ce.; at. wt., 140.25); found with two other metals, lanthanum, and didymium, in cerite. Powdered cerite is made into a thick paste with concentrated sulphuric acid, and heated nearly to redness. The mass is then treated with water, saturated with H2S, filtered, acidified with HCl, and precipitated by oxalic acid. This precipitate heated in the air to redness gives a brown powder of the mixed oxides. Nitric acid dissolves the oxides of lanthanum and didymium, and leaves the oxides of cerium. The oxides of lanthanum and didymium are separated by the repeated crystallization of their sulphates. Cerium is obtained by reducing its chloride with sodium as a gray pow- CERVANTES der which decomposes water slowly. It dissolves in dilute acids with evolution of hydrogen. Cerous oxide, CeO, obtained by igniting the carbonate or oxalate, is a grayish-blue powder, which, in the air, oxidizes into ceroso-ceric oxide, Ce3O4, a yellowish-white powder. The salts of the former are colorless, those of the latter brown-red or yellow.