Both cuprous and cupric oxides are known. Copper(II) oxide or cupric oxide is the inorganic compound with the formula CuO. The basic copper carbonates, malachite and azurite, both decompose forming CO and CuO, cupric oxide. This ingredient maintains cupric ions in solution at an alkaline pH. Many popular vitamin supplements include copper as small inorganic molecules such as cupric oxide. Polyols, compounds containing more than one alcohol functional group, generally interact with cupric salts. One of these used regular injections of copper compounds, including cupric oxide. It may also be regarded as the cupric salt of phosphoric acid. It can also be prepared photochemically, by irradiating cupric hypophosphite with ultraviolet radiation. Cupric hydroxide is a weak base. Cupric sulfate was not as efficient as mercuric oxide, and yielded lower protein results.