Basic Lead Plumbate

A product intermediate between Pb₃O₄ and Pb₂O₃ exists, having the empirical composition Pb₅O₇.3H₂O. Which may be written 3PbO.2PbO₂.3H₂O. It is obtained as an orange-coloured powder by precipitating with alkali hydroxide a solution of lead nitrate to which hydrogen peroxide has been added. It is not simply a mixture of lead monoxide and dioxide, since cold caustic alkali extracts none of the former oxide from it.

Another oxide, having the empirical composition Pb₅O₈, and containing 4.2 per cent, of active oxygen, is formed when the monoxide is heated with oxygen in a pressure furnace as long as combination takes place. This oxide, which is dark brown, and resembles lead dioxide in appearance, may be regarded as lead pyroplumbate, 2PbO.3PbO₂ or Pb₂(Pb₃O₈).

It should be added, however, that Reinders and Hamburger, who have studied the thermal dissociation of red lead and lead dioxide, do not confirm the existence of the intermediate oxides Pb₂O₃, Pb₅O₇, Pb₅O₈.