new mines, that in a short
time there were above seven thousand _Yanaconas_, or Indian labourers,
established in the neighbourhood, who were employed by their Christian
masters in the various operations of these mines. These men laboured
with so much industry, that each Indian, by agreement, furnished two
marks or sixteen ounces of silver weekly to their respective masters;
and so rich was the mine, that they were able to do this and to retain
an equal quantity to themselves[26]. Such is the nature of the ore
extracted from the mineral veins of this mountain, that it cannot be
reduced in the ordinary manner by means of bellows, as is customary in
other places. It is here smelted in certain small furnaces, called
_guairas_ by the Indians, which are supplied with a mixed fuel of
charcoal and sheeps dung, and are blown up by the wind only, without the
use of any mechanical contrivance.

[Footnote 25: This produce is most extraordinarily large, being equal to
_four_ parts of pure silver from _ten_ of ore, or 640 ounces of silver
from the quintal or 1600 ounces of ore. At the present time, the silver
mines in Mexico, which are the most productive of any that have ever
been known, are remarkable for the poverty of the mineral they contain.
A quintal or 1600 ounces of ore affording only at an average 3 or 4
ounces of pure silver. The profit therefore of these must depend upon
the abundance of ore, and the facility with which it is procured and
smelted.--E.]

[Footnote 26: The gross amount of this production of silver, on the data
in the text, is 11,648,000 ounces yearly; worth, at 5s. 6d. per ounce,
L. 3,203,200 sterling; and, estimating silver in those days, at six
times its present efficacy, worth L. 19,219,200 of modern value. In the
present day before the revolutionary troubles, Humboldt estimates the
entire production of gold and silver from Spanish and Portuguese America
at L. 9,787,500; only about three times the quantity said to have been
at first extracted from Potosi alone, and only about half the effective
value.--E.]

These rich mines are known by the name of Potosi, which is that of the
district, or province in which the mountain is situated. Owing to the
easy labour and great profit experienced by the Indians at these mines,
when any of the Yanaconas was once established at this place it was
found almost impossible to induce them to leave it or to work elsewhere;
and indeed, they were here so entirely conceal