Barium permanganate Barium permanganate Barium permanganate is a chemical compound, with the formula Ba(MnO). Barium permanganate may be produced by disproportionation of barium manganate in a mildly acidic solution, or by oxidation of barium manganate with strong oxidants. Preparations relying on aqueous reactions of barium manganate are extremely slow process due to the low solubility of the manganate. Permanganic acid can be prepared by the reaction of dilute sulfuric acid with a solution barium permanganate, the insoluble barium sulfate byproduct being removed by filtering: The sulfuric acid used must be dilute; reactions of permanganates with concentrated sulfuric acid yield the anhydride, manganese
Pewter known as "trifling metal" or "trifle", was used for holloware and is made up of fine metal with approximately 4% lead. The last type of pewter, known as "lay" or "ley" metal, was used for items that were not in contact with food or drink. It consisted of tin with 15% lead. These three alloys were used with little variation until the 20th century. Older pewters with higher lead content are heavier, tarnish faster, and oxidation gives them a darker silver-gray color. Pewters containing lead are no longer used in items that will come in contact with the human body