(The electrolyte is a solution of acidified copper sulphate. The anode is impure copper, whereas, the cathode is a strip of pure copper. ) On passing electric current through electrolyte, the pure copper from the anode dissolves into the electrolyte. An equivalent amount of pure copper from the electrolyte is deposited on the cathode. The soluble impurities go into solution, whereas, the insoluble impurities settle down at the bottom of the anode and are known as anode mud.