rhodium

[Latinized from Gr. rhodon = a rose, from the red color of some of its salts.] Chem.: A tetratomic metallic element belonging to the platinum group, symbol Rh; atomic weight, 1044; specific gravity, 10-6-12; discovered by Wollaston in 1804 in crude platinum. To obtain it, the solution from which platinum, palladium, and iridium have been separated is mixed with hydrochloric acid, evaporated to dryne , and the residue treated with alcohol of specific gravity 0-837, which di olves everything except the double chlorides of rhodium and sodium. On filtering, heating the residue to dryne , and boiling with water, metallic rhodium remains. It is a whitish-gray metal, very hard, le fusible and le ductile than platinum, unalterable in the air at ordinary temperatures, but oxidizing at a red heat. When pure it is unacted upon by the strongest acids, but when alloyed it di olves in nitro-hydrochloric acid. Rhodium forms but one chloride, RhCl3, a brownish-red pidity with which it absorbs oxygen on exposure to air and moisture, being converted into pota ium croconate. rhō-do-, pref. [Gr. rhodon a rose.] Of, pertaining to, or in any way resembling a rose.