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.