Never place the original medal in the apparatus, or the deposited
copper may adhere so tightly to it that the removal destroys the beauty
of the medal. Having taken an impression in sealing-wax, cover the
latter with black-lead, and attach a wire so that it is in contact
with the black-lead. To the wire and cast thus arranged a piece of
sheet or cast zinc, amalgamated with mercury, must be attached, and
we are at once furnished with the materials for the battery, as the
object to be copied supplies the place of the copper. The medal must
always be placed horizontally. Now let the apparatus be charged with
the solution, by pouring into the outer vessel a portion of the coppery
solution, so that it will stand about an inch above the medal; then
pour in the glass the dilute acid to the same height as the former; now
introduce the zinc into the acid, and the object to be copied into the
solution of copper, which will immediately be deposited on the medal,
and when of a sufficient thickness may be taken off.