Oils which contain sulphur-compounds are subjected to a special process of refining in which cupric oxide or litharge is employed as a desulphurizing agent.
After having previously roasted the tube and copper oxide, and reduced the copper spiral a, the weighed calcium chloride tube and potash bulbs are put in position, the boat containing the substance is inserted (in the case of a difficultly combustible substance it is desirable to mix it with cupric oxide or lead chromate), the copper spiral (d) replaced, and the air and oxygen supply connected up. The apparatus is then tested for leaks.
The salts derived from cupric oxide are generally white when anhydrous, but blue or green when hydrated.
Cupric fluoride, CuF 2, is obtained by dissolving cupric oxide in hydrofluoric acid.
It is also obtained by burning the metal in chlorine, by heating copper and cupric oxide with hydrochloric acid, or copper and cupric chloride with hydrochloric acid.
