Potassium Uranyl Carbonate, K₄UO₂(CO₃)₃

Potassium Uranyl Carbonate, K₄UO₂(CO₃)₃, may be prepared by the action of carbon dioxide on potassium uranyl cyanide, or by evaporating at moderate temperature a solution containing potassium bicarbonate and potassium uranate. It crystallises in small hexagonal prisms, which are stable in dry air and dissolve in cold water without decomposition. The solution is hydrolysed on warming, and the addition of alkali causes precipitation of uranyl hydroxide.