ow to a small matter the quantity of silver contained in
each. They then take off the mould, and place the pella or mass with
its copper base on a trivet, or such like instrument, standing over a
great earthen vessel full of water, and cover it with an earthen cap,
which again is covered by lighted coals. This fire is fed and kept
up for some hours, by which the mass of pella below becomes violently
heated, the contained mercury being thereby raised into vapour: But,
having no means of escape through the cap or cover, it is forced down
to the water underneath, where it condenses into quicksilver and sinks
to the bottom. By this contrivance, little of the mercury is lost,
and the same serves over again. But the quantity must be increased,
_because it grows weak_.[2] At Potosi, as Acosta relates, they
formerly consumed six or seven thousand quintals of mercury every
year, by which Some idea may be formed of the silver there procured.

[Footnote 2: This is utterly absurd, as the mercury must be the same
in _quality_ as before, the _quantity_ only being _weakened_.]

On the evaporation of the mercury, nothing remains but a spongy lump
of contiguous grains of silver, very light and almost mouldering,
called _la pinna_ by the Spaniards. These masses must be carried to
the king's receipt or mint, to pay the royal fifth; and are there cast
into ingots, on which are stamped the arms of the crown, the place
where cast, and their weight and fineness. All these ingots, having
paid the fifth, are sure to be without fraud or deceit; but it is not
so with the _pinnas_, as these have often iron, sand, or some other
matter contained within them, to increase their weight; Hence,
prudence requires that these should be opened, and made red hot in a
fire; for, if falsified, the fire will turn them black or yellow, or
melt them more easily. This trial by fire is also necessary to extract
moisture, which they contract in places where they are purposely laid
to render them heavier, as also for separating the mercury with which
the bottom of the mass is always more or less impregnated. The weight
of these _pinnas_ may be increased nearly a third, by dipping them
while red hot into water. It also sometimes happens that the same mass
of pinna may be of different fineness in different parts.

The ore, or stones taken from the mines, or the _mineray_, as it is
called in Peru, from which the silver is extracted, is not always of
the same nature, c