Daniell cell

The original form given to this, the Daniell cell, is shown at Fig.

The Daniell cell consists essentially in a rod or plate of zinc immersed in dilute sulphuric acid, and separated from the copper or collecting plate by a porous earthen pot or cell.

The use of a solution of zinc sulphate to act on the zinc rod, or plate, is always to be preferred in the Daniell cell, when long duration is of more consequence than energetic action.

It may here be noted, that although the effect of mercury in protecting the zinc is very marked in those batteries in which acids are used as the exciting fluids, yet this action is not so observable in the cases in which solutions of salts are used as exciters; and in a few, such as the Daniell cell and its congeners, the use of amalgamated zinc is positively a disadvantage.

The absence of the porous pot decreases the internal resistance, but the electromotive force is the same as in the ordinary type of Daniell cell.