“ Iridium sulphide, IrS, is obtained when the metal is ignited in sulphur vapour. The sesquisulphide, Ir2S3, is obtained as a brown precipitate when sulphuretted hydrogen is passed into a solution of one of the sesqui-salts. It is slightly soluble in potassium sulphide. The disulphide, IrS2, is formed when powdered iridium is heated with sulphur and an alkaline carbonate. ”

“ The double chloride is fused with nitre, the melt extracted with water and the residue fused with lead, the excess of lead being finally removed by solution in nitric acid and aqua regia. It is a brittle metal of specific gravity 22.4 (Deville and Debray) , and is only fusible with great difficulty. It may be obtained in the spongy form by igniting iridium ammonium chloride, and this variety of the metal readily oxidizes when heated in air. ”

“ On evaporating the solution (not above 40° C.) a dark mass is obtained, which contains a little sesquichloride. It forms double chlorides with the alkaline chlorides. For a bromide see A. Gautbier and M. Riess, Ber., 1909, 42, p. ”