CONSUMPTION OF MERCURY. In the mines of Pachuca, Zacatecas, Som- In the mines of Chichiapa, Tetala, Tasco, 225 52 48 In the mines of Temascaltepec, Ayuteco, and Chautla de la Sal 44 In the mines of Zacualpa, San Luis Potosi, 42 The Government regulates the distribution (repartimiento) of silver, according to these data, and the quantity of silver annually extracted from the different districts of mines. The amalgamation of a hundred weight of ores, which contain from three and a half to four ounces of silver, costs in Mexico, including the loss of mercury, from four to five shillings. M. Sonneschmidt calculates the loss of mercury at ten, twelve, or fourteen ounces for eight ounces of silver; and he reckons 8 ounces of mercury consumed (azogue consumido), and from 3 to 6 ounces lost (azogue perdido). From December 1801 till August 1804, Spain received from its colonies 23,250,0947. in gold and silver, and 13,725,9617. in agricultural pro duce. From 1788 to 1795 the total importation was only at an average, from seven to ten millions sterling per annum. The produce of the mines of Spanish America varies a seventh from year to year, or more than 310,000lbs. troy of silver. We have estimated this produce for the Spanish and Portuguese colonies at 17,291 kilogrammes of gold, or 75,217 Castilian marcs, and at 795,581 kilogrammes or 4,460 Castilian marcs of silver, which together are of the value of 9,400,000l. Europe, Siberia, and America furnish per annum 57,368lbs. in gold, and 2,175,000lbs. in silver, or to the value of 10,755,000l. NOTE 1. The Baron de Humboldt proves to us in these remarks that he is well acquainted with practical mining, and that his information is likely to be most valuable on that account. I would particularly direct the attention of English Miners to what is said (page 189) respecting the great size of the shafts and levels, particularly of the latter, and to the influence justly drawn in the following page, that this has prevented the proprietors from making trials which are so indispensable for the preservation of a mine. If these works have not been properly carried on, it may be so much the better for those who are about to commence a new system of operations. Every miner from Cornwall knows that the greater part of the profits on the Mines of that country have of late arisen from a judicious system of exploring ground which had formerly been neglected. It is hoped that experience so valuable for the enterprize in question, will be actively and successfully applied. I have seen many Mines in England and Wales to which M. de Humboldt's remark might have been justly applied, and which were abandoned for want of the trials he recommends. The working of these having been resumed of late years and conducted on a better system, they have become very profitable. The untried ground on the veins between different mines on the same lode, or the high ground standing, should be accurately inspected. There is evidence enough in this chapter that much is to be done, and that a great probability exists of beneficial results. I need hardly say any thing on the mode of drawing the water or the ores, the improvements with respect to which, have been considerable in England in the last twenty years. Every one who is sent to manage mines in Mexico, should of course understand these improvements well. NOTE 2. J. T. On the mode of dressing the ores we have no very precise information; the author praises the trituration or grinding to a fine powder: this is necessary where amalgamation is used, but would be less so for smelting. It appears, however, that their machines only grind from 660 to 880 lbs. in 24 hours. A good stamping mill with 3 heads would probably do 4 times as much; and as 24 heads would be worked by a small steam engine, such a machine would do the work of between 30 and 40 of their mills: consequently, ores that would not pay in the old method, would give large profits by the new. I have said elsewhere, that I conceive it to be a great object to dress the ores as clean as possible, and to reduce the bulk to the smallest possible quantity. This I think must be true, whether amalgamation be used, or smelting, with a scarcity of fuel. It appears that the pyritous ore, or mundic containing silver, which is often very plentiful, is sometimes calcined in reverberatory furnaces or burning-houses. This operation appears to be ill performed, and must be attended to. I should think it an essential process for those ores which are very valuable. In page 206, we are told that smelting is badly performed. The improvement of this process, as well as of that of dressing, will of course demand great attention. Their importance may be estimated by their effect on the consumption of quicksilver, the cost of which, as stated in the latter part of the chapter, forms one of the most formidable deductions from the profits of the mines. J. T. 2 G 2 CHAPTER XI. Intendancy of Guanaxuato.-Situation-extent-cultiva tion-population-towns-mining districts-geological constitution. We shall now subjoin some more particular details concerning the mining districts, and the intendancies in which they are situate; taking them in the order of their comparative wealth and importance. I. Intendancy of Guanaxuato. This province, wholly situated on the ridge of the Cordillera of Anahuac, is the most populous in New Spain. The population is also more equally distributed here than in any of the other provinces. Its length, from the lake of Chapala to the northeast of San Felipe, is 156 miles, and its breadth, from the Villa de Leon to Celaya, 93 miles. Its territorial extent is nearly the same as that of the POPULATION. CULTIVATION. 229 kingdom of Murcia; and in relative population it exceeds the kingdom of the Asturias. Its relative population is even greater than that of the departments of the Hautes-Alpes, Basses Alpes, Pyrenées Orientales, and the Landes. The most elevated point of this mountainous country seems to be the mountain de los Llanitos in the Sierra de Santa Rosa. I found its height above the level of the sea 9235 feet. The cultivation of this fine province, part of the old kingdom of Mechoacan, is almost wholly to be ascribed to the Europeans, who arrived there in the 16th century, and introduced the first germ of civilization. It was in these northern regions, on the banks of the Rio de Lerma, formerly called Tololotlan, that the engagements took place between the tribes of hunters and shepherds, called in the historians by the vague denominations of Chichimecs, who belonged to the tribes of the Pames, Capuces, Samues, Mayolias, Guamanes, and Guachichiles Indians. In proportion as the country was abandoned by these wandering and warlike nations, the Spanish conquerors transplanted to it colonies of Mexican or Aztec Indians. For a long time agriculture made more considerable progress than mining. The mines, which were of small celebrity at the beginning of the conquest, were almost wholly abandoned during the seventeenth and eighteenth centuries; and it is not more than thirty or forty years since they |