"World War II brought great demands on the battery industry. Miniature batteries
were needed to provide power in small devices including watches for the military. Samuel Ruben (an independent inventor) developed
the zinc-mercuric oxide alkaline battery, licensed to the P.R. Mallory Co. (later Duracell, International). This battery gave
five to eight times the service of a similar sized Leclanche battery. The cell was made in sizes as large as a "D" cell and
yields a very reliable 1.35 volts on load rather than the constantly declining voltage of batteries with manganese-dioxide
cathodes. Very few of these cells are produced now because of the manufacturing and disposal problems introduced by the presence
of mercury or mercuric oxide. A modern "button" (or "coin") cell version is shown here."