Explanatory notes
… mentioned in the introduction to this sub‑Chapter, this heading covers : (I) Carbonates (neutral carbonates, … carbonic acid (H 2 CO 3 ), whose anhydride (CO 2 ) falls in heading 28.11. (II) Peroxocarbonates (percarbonates), i.e., … processes give commercial ammonium carbonate which, in addition to various impurities (chlorides, sulphates, …