Explanatory notes
… use, the derived product potassium thiocarbonate ( heading 28.42 ) is sometimes used. (See the Explanatory Note to … With alkali sulphides, it forms thioarsenites of heading 28.42 . (c) Diarsenic pentasulphide (As 2 S 5 ). This … alkali sulphides, it also forms thioarsenates of heading 28.42 . The heading excludes natural arsenic …