The pretended secret of the Alchemists was the transmutation of the
baser metals into gold, which they occasionally exhibited to keep the
dupes who supplied them with money in good spirits. This they performed
in various ways. Sometimes they made use of crucibles with a false
bottom. At the real bottom, they put a quantity of gold or silver. This
was covered by a portion of powdered crucible mixed with gum or wax, and
hardened. The material being put into a crucible and the heat applied,
the false bottom disappeared; and at the end of the process, the gold or
silver was found at the bottom of the crucible. Sometimes, they made a
hole in a piece of charcoal, filled it with oxide of gold or silver, and
stopped up the hole with a little wax; or they soaked the charcoal in
solutions of these metals; or they stirred the mixture in the crucible
with hollow rods, containing oxide of gold or silver within, and the end
closed with wax. By these means, the gold or silver wanted was
introduced during the operation, and considered as a product.
Sometimes the cunning wights used solutions of silver in nitric acid, or
of gold in aqua-regia, or an amalgam of gold or silver, which being
adroitly introduced, furnished the requisite quantity of metal. A common
exhibition was to dip nails into a liquid, and take them out, half
converted into gold. The nails were one-half gold and the other half
iron, neatly soldered together, and the gold was covered with something
to conceal the colour, which the liquid was capable of removing.
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