fumes, but the relative fragility of its thin glass enclosure and the necessity of having to raise the zinc plate when the cell is not in use eventually saw it fall out of favour. The cell was also known as the 'chromic acid cell', but principally as the 'bichromate cell'. This latter name came from the practice of producing the chromic acid by adding sulphuric acid to potassium dichromate, even though the cell itself contains no dichromate. The Fuller cell was developed from the Poggendorff cell. Although the chemistry is principally the same, the two acids are once again separated by a porous container and the zinc is treated with mercury to form an amalgam. Grove cell The Welshman William Robert Grove invented the Grove cell in 1839. It consists of a zinc anode dipped in sulfuric acid and a platinum cathode dipped in nitric acid, separated by porous earthenware. The Grove cell provides a high current and nearly twice the voltage of the Daniell cell, which made it the favoured cell of the American telegraph networks for a time. However, it gives off poisonous nitric oxide fumes when operated. The voltage also drops sharply as the charge diminishes, which became a liability as telegraph networks grew more complex. Platinum was and still is very expensive. Dun cell Alfred Dun 1885, nitro-muriatic acid () – iron and carbon: In the new element there can be used advantageously as exciting-liquid in the first case such solutions as have in a concentrated condition great depolarizing-power, which effect the whole depolarization chemically without necessitating the mechanical expedient of increased carbon surface. It is preferred to use iron as the positive electrode, and as exciting-liquid nitro muriatic acid (), the mixture consisting of muriatic and nitric acids. The nitro-muriatic acid, as explained above, serves for filling both cells. For the carbon-cells it is used strong or very slightly diluted, but for the other cells very diluted, (about one-twentieth, or at the most one-tenth). The element containing in one cell carbon and concentrated nitro-muriatic acid and in the other cell iron and dilute nitro-muriatic acid remains constant for at least twenty hours when employed for electric incandescent lighting. Rechargeable batteries and dry cells Lead-acid Up to this point, all existing batteries would be permanently drained when all their chemical reactants were spent. In 1859, Gaston Planté invented the lead–acid battery, the first-ever battery that could