prov:value
| - Particularly preferred additives in this case are vegetable ashes, insoluble polyquinones, addition products or condensation products of benzoquinone and amines, in particular ammonia, and furthermore lignin, lignin-sulphonic acid, humic acids, diverse fly ashes, bauxite, aluminum oxide, cobalt molybdate, silicon dioxide, active charcoal, zirconium dioxide, nickel oxide, palladium oxide and barium
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