The equilibrium relation among SO₂ gas and oxygen and sulphur in molten copper, calculated from the theoretical equation obtained in the previous report, was numerically compared with the observed data in a reverberatory furnace and a copper alloying furnace. The results obtained may be summarized as follows: The effect of sulphur content in heavy oil is small in anode copper refining and on the other hand, is great in wire bar refining in a reverberatory furnace. If sulphur content in heavy oil is >0.3%, it is obtained numerically that the sulphur content of copper increases rapidly from 0.005% to 0.007% when the oxygen content is <0.045∼0.05%, and the partial pressure of SO₂ is 1×10⁻³∼5×10⁻⁴ atmosphere at 1200°. In these cases, many large blowholes appear in the cast copper. This phenomenon is so called overpoling due to SO₂ gas evolution. Next it is shown that in a copper alloying furnace, the observed data are approximately distributed on the equilibrium curves.