- Brines containing bases but not sulfates;
- Potassium permanganate, occurring at fermenting and purification installation;
- Sodium carbonate and potassium carbonate;
- Bases, provided that their concentrations are not excessively high;
- Oxalic acid occurring at tanneries; and
- Mineral oils and petroleum products (benzene, kerosene, cutback oil, naphtha, paraffin, tar) as long as these contain no acids that can remain in the products after chemical treatment.