64

yielded 50 marcs per quintal were considered extremely rich. Moreover according to the report of Don Francisco Texada on the mines of Gaudalcanal in Spain, in 1607 the mean wealth of the minerals of Potosi was not above an ounce and a half. Since the commencement of the 18th century, they reckon only from 3 to 4 marcs per caxon of 5000 pounds, or from 48 to per quintal. The minerals of Potosi are consequently extremely poor, and it is of their abundance alone, that the still in such a flourishing state. prising to see that from 1574 to mean riches of the minerals have diminished in the proportion of 170 to 1, while the quantity of silver extracted from the mines of Potosi, has only diminished in the proportion of 4 to 1.

on account works are

It is sur

1789, the

From 1545 till 1571 the silver minerals of Potosi were all smelted. The knowledge of the conquistadores being confined to military affairs, they were unacquainted with the carrying on of metallurgical processes. They did not smelt the mineral by means of bellows, but they adopted the whimsical method employed by the Indians in the neighbouring mines of Potosi, which had been wrought on account of the Inca, long before the conquest. They established on the mountains which surround the

town of Potosi, wherever the wind blew with impetuosity, portable furnaces, called huayres or guayaras in the Quichua language. These furnaces were cylindrical tubes of clay, very broad, and pierced with a great number of holes. The Indians threw in bed by bed silver mineral, galena, and coal; and the current of air which entered at the holes into the interior of the huayre quickened the flame, and gave it a great intensity. When they perceived that the wind blew too strong, and that too much fuel was consumed, they carried their furnaces to a lower situation. The first travellers who visited the Cordilleras, all speak with enthusiasm of the impression made on them by the first appearance of more than 6000 fires, which illuminated the summits of the mountains round the town of Potosi. The Indians extracted the galena necessary for their smelting, from a smaller mountain, in the vicinity of the Cerro de Hatun-Potocsi called the child, or Huayna Potocsi*. The argentiferous masses which

*Properly the Father mountain and the son-mountain. The different summits of the Volcan de Pichincha, bear analogous denominations; and it is because the French academicians have not distinguished in their works the old Rucu-Pichincha from the young, or Guagua-Pichincha, that it is so difficult to find the place of the academical station of Bouguer, La Condamine, and d'Ulloa. (See my Recueil d'Observations Astronomiques. vol. i. p. 308.)

came out of the huayres established in the mountains, were resmelted in the cottages of the Indians, by means of the old process of blowing the fire by ten or twelve persons at once, through tubes of copper, of one or two metres in length, and pierced at the lower extremity with a very small hole. It is easy to conceive what an enormous quantity of silver must have remained in the scoria without combining with the lead.

Pedro Fernandez de Velasco, who, it is expressly said by the jesuit Acosta,* "had seen in Mexico how the silver was extracted. from the mineral by means of mercury," proposed to Francisco de Toledo, viceroy of Peru, to introduce amalgamation into Potosi. He succeeded in his attempts in 1571; and of the eight or ten thousand quintals of mercury produced by the mine of Huancavelica towards the end of the 16th century, more than from six to seven thousand were consumed in the works of Potosi. The minerals which during the first years had been considered too poor to be smelted in the huayres, were now wrought to advantage.

The abundance of rock salt wrought on the table land of the Cordilleras near Cuchuara, Carangas, and Yocalla, facilitates very

* Acosta, p. 146.

much the amalgamation of Potosi.

According

to the calculation of Alonzo Barba,* there was consumed between 1545 and 1637 the enormous quantity of 234,700 quintals of mercury. From 1759 to 1763, the consumption was between sixteen and seventeen thousand quintals annuallyt. Towards the end of the 16th century, 15,000 Indians were compelled to work in the mines and amalgamation works of Potosi, and there was daily brought to the town, more than 1500 quintals of salt of Yocalla. At present there are not more than 2,000 miners, who are paid at the rate of 50 sous per day. Fifteen thousand llamas, and an equal number of asses are employed in carrying the ore from the mountain of Hatun-Potocsi to the amalgamation works. In 1790 there was coined at the mint of Potosi 4,222,000 piastres, viz. 299,246 piastres, or 2204 marcs in gold, and 3,293,173 piastres, or 462,609 marcs in silver.

When we reflect on the history of the precious metals, and the interest taken in them by those who engage in investigations of political economy, it will not be deemed surprising that we have so minutely explained those facts,

which may throw some light on the quantity of silver extracted during two centuries and a half from the mines of Potosi. It was necessary to compare the testimonies of the first Spanish authors who visited America; to distinguish between the produce of exportation, and the fifth payable to the crown; and between the piastres, an imaginary coin, used in the beginning of the conquest, and the Peruvian piastres of eight reals. Had we neglected these investigations which have never been made hitherto, we should have run the risk of increasing the mass of silver imported into Europe since 1492, more than 57 millions of marcs equal to two thousand five hundred millions of livres tournois*.

IV. The Kingdom of New Grenada produces on an average, 18,300 marcs of gold annually. The following tables specify the coinage in the mint of Santa Fe, between the 1st of January, 1789, and the 31st December, 1795, and in the mint of Popayan, between 1788 and 1794.

* £102,040,800, Sterling. Trans. +12,049 lb, troy. Trans.