Battery, Water

A voltaic battery, whose exciting fluid is water. They are used for charging quadrant electrometer needles and similar purposes. They polarize very quickly and are of high resistance. Hence very small plates in large number can be used without impairing their advantage. Rowland's water battery dispenses with cups and uses capillarity instead. The zinc and platinum or copper plates of a couple are placed very close together, while the couples are more distant. On dipping into water each couple picks up and retains by capillarity a little water between its plates, which forms the exciting fluid. Many hundred couples can be mounted on a board, and the whole is charged by dipping into water and at once removing therefrom. It then develops its full potential difference. IMG:8956969607833025625_077F55.jpg: Fig. 55. SECTION OF WOLLASTON BATTERY. IMG:8956969607833025625_077F56.jpg: Fig. 56. PLATES OF WOLLASTON'S BATTERY. 78   STANDARD ELECTRICAL DICTIONARY.