It forms crystallizable salts with potassium and calcium hydrates, and functions as a weak acid forming salts named plumbates.
The element is insoluble in water, but dissolves in concentrated sulphuric acid forming a deep red solution.
Chromium sesquioxide is a basic oxide, although like alumina it acts as an acid-forming oxide towards strong bases, forming salts called chromites.
Cuprous oxide is reduced by hydrogen, carbon monoxide, charcoal, or iron, to the metal; it dissolves in hydrochloric acid forming cuprous chloride, and in other mineral acids to form cupric salts, with the separation of copper.
It dissolves in ammonia with the liberation of nitrogen and the formation of silver oxide, Ag 2 O; and in sulphuric acid forming a fairly stable dark green liquid which, on dilution, gives off oxygen and forms silver sulphate.
