work the form of a cylinder, whose axis is inclined from north to south. Near the surface in the Brocal, the metalliferous bed has scarcely ever been wrought on the south side; but on the other hand, in the depth at Cochapata, the galleries have been for a very small way carried northwards. This particular disposition of the works has given reason for believing the cinnabar is lost towards the bottom of the mine; but if it has been found in less abundance, it is because in going deeper and deeper towards the south, they gradually entered the sterile part of the bed of quartzy sandstone.

Notwithstanding the justness of these considerations, it seems by no no means prudent to advise the clearing out of the old mine; for this operation must require an immense expense, and the old works were so badly disposed that it is impossible to derive any advantage from them. The metalliferous bed of the Cerro de Santa Barbara extends many leagues beyond Sillacasa, even as far as above the village of Guachucalpa; and by beginning to work on points which have hitherto remained untouched, there would hardly be a doubt of the success of the operations; for nothing can be a stronger proof of the abundance of the mercury in this part of the Cordilleras, than

the produce of the petty labours of the Indians. If small veins of cinnabar merely uncovered at their surface, yield annually, on an average 3,000 quintals, we cannot entertain a doubt that works of investigation directed with intelligence will one day produce more mercury than is requisite for all the amalgamation of Peru. We may also hope that in proportion as the inhabitants of the new world shall learn to profit from the natural wealth of the soil, the improvement of chemical knowledge will discover processes of amalgamation by which less mercury is consumed. In 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 2500 metres 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;

* Near Tausa, Canoas, and in the Cerro de Suba, in the road from Santa Fé de Bogota to the salt mine of Zipaquira.

† 8201 feet. Trans.

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.*

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 table lands of Mexico resemble in this respect those of Thibet and Tartary. We have already observed, in our description of the valley of Tenochtitlan,

* There are salt springs on the banks of the Lake Dauphin and the Lake of Slaves (des esclaves). Coal has been found near the river Mackenzie, in the latitude of 66°; and at the foot of the stony mountains in the 52° and 56° of latitude. (Mackenzie's Travels in North America, 4to.)

that the Indians who inhabit the caverns of the porphyritic rock called Peñon de los Baños, lixiviate the earth which is impregnated with muriate of soda. It is a received opinion in the country that this salt, like the nitrate of potash, is formed by the agency of the atmospheric air; and in fact it appears that the muriate of soda is merely found in the upper bed of earth to the depth of eight centimetres.* The Indians pay a small sum to the proprietors of the soil for the permission of carrying off the first saliferous bed, knowing that after a few months they will find a crust of clay full of muriate of soda and lime, nitrate of potash and lime, and carbonate of soda, M. del Rio, a distinguished chemist, proposes to make accurate experiments on these phenomena, by lixiviating the new surface before it has again been exposed to the atmospheric air. 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 consumption of salt would be very inconsiderable in Mexico, because the Indians, who

* 3 inches. Trans.

constitute a great part of the population, have never abandoned the old custom of seasoning their food with chile* or pimento instead of salt.

In taking a general view of the mineral wealth of New Spain, far from being struck with the value of the actual produce, we are astonished that it is not much more considerable. It is easy to foresee that this branch of national industry will continue augmenting as the country shall become better inhabited, as the smaller proprietors shall enjoy more fully their natural rights, and as geological and chemical knowledge shall become more generally diffused. Several obstacles have already been removed since the year 1777, or since the establishment of the su preme council of mines, which has the title of Real Tribunal general del importante cuerpo de Mineria de Nueva España, and holds its sittings in the palace of the viceroy at Mexico. Till that period the proprietors of mines were not united into a corporation, or the court

* Chilli or ahi. See vol. ii. p. 505. If we estimate the annual consumption of muriate of soda in Europe at 6 kilogrammes a head, (13.2 lib. avoird. Trans.) we dare not estimate the consumption of the copper-coloured race at more than half a kilogramme (about a pound. Trans.)