Lead Metaplumbate, Pb₂O₃

Lead Metaplumbate, Pb.PbO₃, prepared from the calcium salt, is identical with lead sesquioxide, Pb₂O₃, to which Marino attributes the constitutional formula:



This oxide is, however, usually prepared by carefully adding hypochlorite solution to a cold solution of alkali plumbite. It may also be obtained by adding very dilute ammonia to an acetic acid solution of red lead, or by heating lead monoxide or dioxide to 350° C. in air or oxygen, oxygen being absorbed or evolved so that Pb₂O₃, the most stable product at this temperature, may be formed. Lead sesquioxide is a reddish yellow amorphous powder which behaves towards acids similarly to red lead, in accordance with the fact that it is lead metaplumbate. A hydrated form of lead sesquioxide, to which Bellucci and Parravano attribute the constitutional formula Pb[Pb(OH)₆], is obtained by precipitating an alkaline solution of lead monoxide with potassium plumbate.