Thorioi, Or Thorinum, a rare metal discovered in 1828 by Berzelius in a black mineral called thorite, found in a syenitic rock in Norway. It is obtained by reducing the chloride with potassium or sodium. It is a gray metallic powder having much resemblance to zirconium, and acquires a metallic lustre by pressure. Its specific gravity is 7.6 to 7.8; symbol, Th. It takes fire when heated considerably below redness, and burns with great brilliancy, forming thorina, Th02, a white substance of sp. gr. 9.402. Thorinic chloride, ThCl2, is prepared by passing dry chlorine over a heated mixture of thorina and charcoal. It crystallizes in rectangular four-sided tables, which are deliquescent and very soluble in water. Thorinic sulphate, with potassic sulphate, forms thorinic potassic sulphate, K2S04,ThS04,H20, which is soluble in water, but is precipitated by a saturated solution of potassic sulphate. Thorinic sulphate is characterized by being precipitated by boiling its solution, which re-dissolves on cooling. Oxalic acid gives with salts of thorium a white insoluble oxalate of the metal.