Copper sulfide English name: Cupric sulphide Molecular formula: CuS · H2O Molecular weight: 113.62 Properties: dark brown amorphous powder or granular material. Soluble in dilute nitric acid, hot concentrated hydrochloric acid, sulfuric acid and sodium cyanide solution, slightly soluble in ammonium sulfide solution, insoluble in water and sodium sulfide solution. It can be oxidized into a colloidal state in moist air. The conductivity is better than cuprous sulfide. Heating to 220 ° C decomposed into cuprous sulfide.