siding.

The chloride concentration of copper-refining electrolyte is correlated with the cathode polarization and also with the grain size and the hardness of the copper deposit. It is shown that the curves have a break at the chloride concentration of about 15 mg./L. The variation of the cathode polarization is explained on the assuinption that the electro-chemical reaction Cu++-[- e ~=t Cu + is a slow process and that the electrochemical reaction Cu ++ + 2 C1- + e--> CuC12- may take place. The variations of the hardness and the grain size are explained accordingly by the polarization phenomena