THORIUM

(Lat.), n. n. Thor'ia-u3m(um). Fr., t. Ger., T. Also written thorinum. A metallic element discovered by Berzelius in 1828. It occurs in certain rare minerals. It has been prepared in the pure state as a gray, lustrous powder of sp. gr. 7'66 to 7'95. In composition it acts as a tetrad. Symbol, Th; atomic weight, 231'S. [B.] [s. 620]