Molybdenum Trisulphide, MoS₃

Molybdenum Trisulphide, MoS₃, is obtained by saturating an alkali molybdate with hydrogen sulphide (or by adding thereto ammonium sulphide), and decomposing the thiomolybdate so formed by warming with dilute hydrochloric or sulphuric acid. There is thus obtained a reddish-brown gelatinous precipitate, which on drying becomes dark brown. It is slightly soluble in water and in aqueous potassium hydroxide, but easily soluble in a solution of potassium sulphide. On heating it yields the disulphide MoS₂; at a high temperature in hydrogen it is reduced to the metal. Molybdenum trisulphide has been prepared in the colloidal condition.