The application of steam power would to a certain extent remedy the above-mentioned defect, but the cost of such a method, compared to that of a Voltaic arrangement, would be far too great to allow of its superseding the latter arrangement. _Von Ebner's Voltaic Battery._--This form of Voltaic battery, which may be considered as a modification of that known as Smee's, was designed by Baron von Ebner, colonel of the Austrian imperial corps of engineers, for use in connection with the Austrian system of submarine defence, by self-acting electrical mines. A section of one of these cells is shown at Fig. 72. It consists of a glass vessel _a_, to contain the diluted sulphuric acid, within which is suspended a plate _b_ of platinised lead, which is bent round into a cylindrical form to fit close around the inner surface of the glass vessel. In the centre of this latter is hung a porcelain perforated cup _c_, containing some cut-up zinc and mercury to keep it (the zinc) amalgamated. The top of each cell is furnished with a porcelain cover, through which the wires attached to the positive and negative poles of the cell project. Due to the large quantity of liquid contained in the cell, the tendency to alter its internal resistance is retarded; also by the arrangement of the porcelain cup, above detailed, the consumption of zinc and mercury, which in an ordinary Voltaic battery is very considerable, is materially diminished. _Chromic Acid or Bichromate Battery._--This form of battery is very similar to Grove's, the difference being that, in the place of the nitric acid as the exciting liquid, either chromic acid, or a solution of bichromate of potash, sulphuric acid and water is substituted. A form of this battery, as designed by Dr. Hertz, is used in connection with the German system of torpedo defence. _Leclanché Voltaic Battery._--This form of Voltaic battery was invented by M. Leclanché, some twelve years ago. At Fig. 73 is shown a cell of this battery in its original form. The positive pole _a_ consists of a plate of graphite in a porous pot _b_, and surrounded by a mixture of peroxide of manganese and graphite. The negative pole _c_ is a rod or pencil of amalgamated zinc. The whole is enclosed in an outer vessel of glass _d_ containing a solution of sal ammoniac.