Thorium Sulphide, ThS₂

Thorium Sulphide, ThS₂, and Oxysulphide, ThOS. - Berzelius obtained a yellow powder and Nilson a black substance by heating thorium in sulphur vapour. Chydenius heated thoria to a high temperature in a stream of hydrogen containing carbon disulphide vapour, and obtained a black product having a density of 8.29. Kruss obtained a brown product, probably the oxysulphide, by the action of hydrogen sulphide on thorium halides; and Hauser prepared the same substance by heating carefully dried thorium sulphate to low redness in a current of hydrogen sulphide. Lastly, Duboin heated a mixture of thorium chloride with excess of sodium or potassium chloride in a porcelain boat contained in a tube through which a current of dry hydrogen sulphide was passed. The product, after washing out the alkali chloride, contained brown lamellae of thorium sulphide, ThS₂, having a density of 6.7. After the removal of these lamellae by sifting, the siftings were treated with nitric acid at 40° C., which dissolved the remaining ThS₂ and left the oxysulphide ThOS in the form of yellow crystals; these are only very slowly acted on by nitric acid, and have a density of 8.42.