Barium ferrate hydrochloric acid, releasing chlorine. The irreversible reaction of digesting barium chromate with a solution of sodium ferrate forms barium ferrate, and the color of the solution is changed from red to yellow due to the sodium chromate that is also formed. Alkaline sulfates decompose barium ferrate that has not been dried, forming barium sulfate, ferric hydroxide and oxygen gas. Barium ferrate, therefore, appears to be one of the most insoluble salts known. Barium ferrate Barium ferrate is the chemical compound of formula BaFeO. This is a rare compound containing iron in the +6 oxidation state. The ferrate(VI) ion has two
Calamine brass Calamine brass Calamine brass is brass produced by a particular alloying technique using the zinc ore calamine directly, rather than first refining it to metallic zinc. Direct zinc smelting appears to have been unknown in Europe until the mid-18th century, even though the alloyed calamine brass was in use for centuries, and metallic zinc was produced directly via reducing-atmosphere smelting in India and China from the 12th century CE onwards. Brass is an alloy of copper and zinc and, when it was first developed, methods for producing metallic zinc were unknown. Metallurgists wishing to produce brass thus used calamine (actually