Electrical observers have experienced three important defects in the common galvanic trough battery, as constructed by Cruickshanks, namely, that the zinc is deposited on the copper plates, that the zinc plates become gradually covered with a coating of oxide of zinc, and that the hydrogen formed by the decomposition of water adheres in globules to the surface of the copper; the result of all which circumstances is, that the galvanic action quickly decreases in force. These inconveniences have been in part removed in the battery of Professor Daniell, in which the zinc plates are covered by an animal membrane, and sulphate of copper is substituted for acids to form an exciting solution.