On the first discovery of the mine of Potosi, the metal was much purer than it is at present, being now greatly reduced, and even inferior to many of the other mines. It is the abundance of the ore alone, which renders it worth working. According to Acosta, the average con tents of silver in the crude ore were, in 1574, from 8 to 9 marks per quintal ; and the minerals, which yielded 50 marks per quintal, were considered as extremely rich. Since the beginning of the 18th century, however, they reckon only from 3 to 4 marks per caxon,• or from to per quintal. From this it appears, that the mean riches of the minerals have diminished in the proportion of 170 to 1 ; but what is surprising, the quantity of silver extracted from the mines of Potosi has only diminished in the proportion of 4 to 1, as will be seen in the follow ing calculations, which are given by Humboldt in a more extended form.
1. From the opening of the mines of Potosi in 1545 to the year 1556, when the royal duties were first recorded with accuracy, Ulloa, upon the authority of Don Sebasti ani Sandoval y Guzman, who published an account o [these mines in 1634, entitled Pretensiones del Potosi, makes the total produce which paid duty to be 613 millions of piastres, making an yearly average of 55,726,000 piastres, or 6.556,000 marks of silver. This immense sum however, Humboldt, upon no less unquestionable data, has redu ced to 127,500,000 piastres, or 15,000.000 of marks, mak ing an annual produce of nearly 1,363,6361 marks.
2. The royal dutiest paid on the silver extracted front the mines of Potosi, between the 1st of January 1556, and the 31st of December 1578, during which the fifth only was paid, amounted to 9,801,906 piastres, making a total produce of 49,009,530 piastres ; or 5,765,827 marks of silver, which, for 23 years, makes the average annual produce of 250,688 marks.
3. The duties paid from the 1st of January 1579 to the 19th of July 1736, during which one and a half per cent. de covost was first paid, and then the fifth of the remain ing 981 piastres, amounted to 129,417,273 piastres, mak ing a total produce of nearly 610,458,835 piastres, or 71,818,6861 marks of silver, which, for l572 years, is at an annual average produce of nearly 455,9911 marks.
4. Between the 20th of July 1736, and the 31st of De cember 1789, during which the one and a half per cent. de covos and the half of the fifth only were paid, the royal duties amounted to 14,542,684 piastres, making a total produce of 128,129,374i piastres, or, 15,074,044 marks of silver, which, for 531 years, makes an annual produce of nearly 281,758 marks.
5. From 1789 to 1803, we have no account of the royal duties ; but during that period the total produce of Po tosi, according to the records of the mint, were 46,000,000 of piastres, or 5,411,764 marks, making an yearly aver age of 386,5541 marks.
From these calculations, it appears that the annual produce of the last period is little more than a fourth of that of the first ; but in giving the average produce for periods of such a length, the gradual diminution or in crease of the quantity of silver extracted from these mines could not be distinctly marked. We may therefore ob serve, that during the second period, when the royal du ties were first correctly registered, the king's fifth varied from 500,000 to 300,000 piastres ; and that during the first 50 years of the third period, the duties varied from 1,000,000 to 1,500,000 piastres ; and then gradually diminished until 1735, when they only amounted to 271,621 piastres, 6 reals. From 1737 to 1789, the in crease was equally gradual from 183,704 to 335,468 pi astres We may also remark, that in these calculations, we have uniformly valued the piastre at only 8 reals de plate, while we arc that until near the close of the 16th century, the Spaniards reckoned by piastres of 480 maravedis, or nearly 131 reals de plata. In estimat ing, therefore, the total produce of these mines from 1545 to 1803, allowance must be made for this low valuation.
The quantity of silver extracted from the mines of Po tosi during the From this statement of the wealth drawn from one mint, the reader is noL to conclude, that the other mines of Buenos Ayres are in any degree equally productive. 01 the immense quantity of silver prouuced by this vice royalty, the single mute of Potosi furnishes more than three fourths. None of the rest are so constantly wrought, being either interrupted by inundations or de stroyed by neglect. In the district of Caranges, detach ed pieces of silver, unmixed with any ore or stone, are found in the sandy deserts extenoing towards the coast of the South Sea. These pieces are called papas or yams, being taken out of the sand in the same manner as that root is taken out of the ground, and arc of various forms and sizes. Two marks or 16 ounces is the general weight ; but Ulloa mentions two papas which he saw at Lima, one weighing 60 and the other 150 marks.