MERCURY-COAL.

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will be more attentive to their common interests: it becomes, therefore, of consequence to observe the indications of mercury in South America. Mexico and Peru, instead of receiving this metal from Europe, will one day, perhaps, be able to supply the Old world with it.

We may also hope that, in proportion as the inhabitants of the New world shall learn to profit by the natural wealth of the soil, the improvement of chemical knowledge will discover processes of amalgamation by which less mercury is consumed. By diminishing the consumption of this metal, and increasing the produce of the indigenous mines, the American miners will gradually learn to dispense with the mercury of Europe and China.

To complete the view of the mineral substances of New Spain, it remains for us to name coal, salt, and soda. The coal, of which I saw in the valley of Bogota beds at 7,500 feet of elevation above the level of the sea, in general appears to be very rare in the Cordilleras. In the kingdom of New Spain it has only yet been discovered in New Mexico; it is however probable that it may be found in the secondary formations which extend to the north and north-west of the Rio Colorado, as well as in the plains of San Luis Potosi and Texas. There is already a coal mine near the sources of the Rio Sabina. In general, coal and rock salt abound to the west of the Sierra Verde near the lake of Timpanogos, in Upper Louisiana, and in those vast northern regions situated

between the stony mountains of Mackenzie and Hudson's Bay.

Deposits of coal abound beyond the tropics in New Mexico, in the middle of the salt plains of Moqui and Nabajoa, and to the east of the Rocky Mountains, as also towards the sources of the Rio Sabina, in that immense basin covered with secondary formations, in which flow the Missouri and the Arkansas.

An able engineer, M. Lafond, whose inap throws much light on these countries, observes, that eight leagues north from the post of Chichi there are hills abounding in coal, from which a subterraneous noise is heard at a distance like the discharge of artillery. Does this curious phenomenon announce a disengagement of hydrogen produced by a bed of coal in a state of inflammation?

In the whole inhabited part of New Spain, there is no rock salt like that of Zipaquira in the kingdom of Santa Fe, or of Wieliczka in Poland. The muriate of soda is no where found collected in banks or masses of considerable volume; it is merely disseminated in the argillaceous soil which covers the ridge of the Cordilleras.

The most abundant salt mine of Mexico is the lake of the Peñon Blanco, in the intendancy of San Luis Potosi, of which the bottom is a bed of clay which contains from 12 to 13 per cent. of muriate of soda. We ought also to observe, that were it not for the amalgamation of silver ores, the con

sumption of salt would be very inconsiderable in Mexico, because the Indians, who constitute a great part of the population, have never abandoned the old custom of seasoning their food with chile or pimento instead of salt.

NOTE A.

In speaking of the common metals which may be found in Mexico, I think the probability of their value, as an object of research, is overrated. Not that I doubt that they may be found, and perhaps in some instances abundantly; but unless fuel could be supplied in much larger quantity than at present, it cannot pay to work them.-For instance, iron and copper require such a great weight of coal that they cannot be worked to advantage without it; and when we take into account the expense of transporting and erecting machinery, the fuel required for merely draining the mines, the rate of wages of the miners of Mexico, and the charge of carrying the produce to the coast, we shall see at once, that though all these expenses may be borne by silver and gold mines, nothing but a great falling off in the supply from other countries, and a proportionable advance in price, can warrant the application of them to mines of the inferior metals.

An exception may be made in respect to mercury and lead.The former may indeed be reckoned as a precious metal, and one of which the supply is limited, being only now found in Spain and Germany: it is also, according to the present practice, essential in Mexico for the extraction of gold and silver from the ores: and though I am of opinion that, if fuel can be obtained, it would be better to discontinue the use of mercury, yet I would strongly recommend M. de Humboldt's remarks to the attention of persons working mines in Mexico, and that

every inquiry and research should be made as to veins likely to produce quicksilver.

If smelting should ever be extensively practised in Mexico instead of amalgamation, lead would be the substitute for quicksilver, and a great consumption of it would take place, as in the process much would be dissipated or destroyed. This demand for it on the spot would render it valuable, and it would be applied in the state of ore. There is also every reason to think that the lead ores of Mexico may frequently contain silver in sufficient proportion to make it worth while to work them. J. T.

NOTE B.

Coal.-M. de Humboldt mentions this substance in the preceding chapter as having hitherto been found only in New Mexico, which is far too distant north for the supply of any of the mines now likely to be worked. It has however been also found in Peru and Chili, and some late accounts warrant the belief that it may be yet discovered within reach of the silver mines.

In a letter which I had the honour to receive, containing some information from M. de Humboldt himself, dated at Paris, on the 12th Jan. last, (1824,) he tells me, that " he thinks that he "has insisted too much in his works upon the difficulties of "supplying fuel for steam engines: That this difficulty is not so great in general in Mexico as in Peru, as far as relates to "wood; because, in the latter, nature has deposited the mineral "treasures at such great elevations, that they are found almost " at the highest limits of all vegetation; whereas, upon the ta"ble-land of Mexico, though wood is not plentiful, yet a good

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deal is to be found, as at Guanaxuato, from its proximity to "the Sierra de Santa Rosa: That there are also good woods near Real del Monte, at l' Oyamel, and at Cerro del Sacal." He also says, "that some coal has been found, but that he "does not know of any in the domains of Count Regla," which had been reported to be the case; and he goes on to observe, "that the formations of basalt and amygdaloid, which are common there, might indicate the presence of Lignite or Bovey "coal, which would be very useful."

This observation of M. de Humboldt has, in some degree, been confirmed, as there have lately arrived in England some specimens of a kind of coal from the district he speaks of, which, though not exactly the same as the one he mentions, is nearly allied to it, and appears to be what Professor Jameson has called pitch coal. It has the appearance of jet, is found in several coal-fields in Scotland, in some in England, and in Hungary, where the minerals generally remarkably resemble those of Mexico.

The letter above mentioned goes on to say, "that he had seen secondary formations resting upon the metalliferous porphyries about Actopan and Totonilcos; so that, geognostically "speaking, it is possible that true coal might be discovered "there." Some further remarks on this subject will be found

in the next chapter.-J. T.

S