t. This
certainly may be the case with particular mines; but, on the whole,
the quantities of silver now annually obtained from the mines in
Spanish America, abundantly exceeds what used formerly to be procured.
Those mines which are at present [1720] most remarkable in Peru are,
Loxa, Camora, Cuenca, Puerto-veio, and St Juan del Oro. Those of Oruro
and Titiri are neglected; and those of Porco and Plata are filled
up. At Potosi there are a vast number of mines; and those of Tomina,
Chocaia, Atacuna, Xuxui, Calchaques, Guasco, Iquique, &c. are all
wrought with more or less profit, according to the skill of the
proprietors or managers. It is generally believed that the Creoles
have a very perfect acquaintance with the minerals, from experience,
and with the art of treating them, so as to obtain the largest profit;
but, when their utter ignorance in all other arts is considered, their
constant going on in the old beaten track, and their enormous waste of
quicksilver, one is tempted to believe that our European miners might
conduct their works to still greater advantage.

The most perfect silver that is brought from Peru is in the forms
called _pinnas_ by the Spaniards, being extremely porous lumps of
silver, as they are the remainder of a paste composed of silver dust
and mercury, whence the latter being exhaled or evaporated, leaves the
silver in a spongy mass, full of holes, and very light. This is the
kind of silver which is put into various forms by the merchants, in
order to cheat the king of his duty; wherefore all silver in this
state, found any where on the road, or on board any ship, is looked
upon as contraband, and liable to seizure.

In regard to the art of refining, I propose to shew the progress of
the ore, from the mine till it comes to this spongy mass or cake.
After breaking the stone or ore taken out of the veins, it is grinded
in mills between grindstones, or pounded in the _ingenious reales_,
or royal engines, by means of hammers or beetles, like the mills for
Paris plaster. These generally have a wheel of twenty-five or thirty
feet diameter, with a long axle or lying shaft, set round with smooth
triangular projections, which, as the axle turns, lay hold of the iron
hammers, of about two hundred-weight each, lifting them to a certain
height, whence they drop down with such violence that they crush and
reduce the hardest stones to powder. The pounded ore is afterwards
sifted through iron or copper siev