Grove Cell

Grove Cell is a good form of primary battery possessing the advantages of high and constant electromotive force and low resistance. Its disadvantages are that noxious fumes are given off when the battery is working and that the cell is expensive. It is a double-fluid battery, consisting of a zinc plate immersed in dilute sulphuric acid in an outer earthenware vessel and a platinum sheet in an inner porous pot containing strong nitric acid. The zinc, dissolving, causes the production of zinc sulphate and hydrogen. This latter gas is prevented from producing a back electromotive force that would diminish the efficiency of the battery, by passing through the porous vessel into the nitric acid. Here it is oxidised and converted into water, nitric oxide gas being evolved at the same time. The e.m.p. produced is nearly two volts, and if the inner pot be flat-sided and the slab of zinc bent round so as to surround the porous pot, the internal resistance of the battery may be made very small. Bunsens modification consists of the introduction of a slab of carbon in the place of the platinum sheet. The e.m.p. is a trifle higher, and the cell is much cheaper.