(α) Basic carbonate of copper.
(β) Basic carbonate and sulphide of copper.
(γ) Malachite (normal carbonate of copper), with occasional admixture of cuprous oxide and azurite (acid carbonate of copper) [Stolba].
(δ) Crystalline cuprous oxide, according to Wibel[36] a reduction product of the carbonate of copper, by the action of the copper of the bronze.
Lastly, copper chloride has been occasionally found in patina [Haidinger][37]. This is only to be expected from the varying character of the localities in which the statues or bronzes are found. The author has himself noticed on board ship, how objects of copper and brass, which are exposed to the salt spray, develop a durable coating of copper oxychloride[ [38] (atacamite).
In conclusion, reference may be made to a statement of Chevreul[ [39], who, after examination of both hollow and solid specimens of Egyptian statuettes, states that the bronze is of an excellent quality and that it occurs in four different conditions. He describes these four conditions, three of which are undoubtedly patina or altered copper, as follows:
(α) A green deposit with patches of blue.
(β) A blood-red mass.
(γ) A reddish coloured bronze.
(δ) Ordinary bronze unaltered in appearance.