I finish the survey of this singular mine perfectly free from foul air or fire-damp; ascend as I came down; and, by vigorous rubbing with soap-and-water, am slowly restored from bright vermilion to my normal colour.
The ore, on reaching the surface, is conveyed by the tram-cart to the sorting-shed, where it is broken and carefully picked over by skilful hands, great caution being needed in selection, as much valuable ore might be thrown away, or a large quantity of useless rock taken to the smelting-furnaces. The picked ore is placed in large bags made of sheepskin, weighed, and then hauled by the mules to the lower works.
Near the mine is a primitive kind of village, the abode of the miners, sorters, and ore-carriers, who are principally Mexicans; dirty señoras in ragged finery, dirtier children devoid of garments, together with dogs, pigs, poultry, and idle miners playing monte on the doorsteps, contrast sadly with the exquisite little village at the works.
Descending from the mine to the level ground by a short track down the hillside, through scenery indescribably picturesque, I reach the smelting furnaces; these, occupying about four acres of land, are built of brick, admirably neat, and well contrived. As quicksilver is found in several forms—namely, native quicksilver, occurring in small drops, in the pores or on the ledges of other rocks, argental mercury, a native silver amalgam, and sulphide of mercury or cinnabar, different processes are requisite for its reduction. Here it is found solely in form of cinnabar, and to reduce it a kind of reverberatory furnace is used, three feet by five, placed at the end of a series of chambers, each chamber seven feet long, four wide, and five high. About ten of these chambers are arranged in a line, built of brick, plastered inside, and secured by transverse rods of iron, fitted at the ends with screws and nuts, to allow for expansion. The top is of boiler iron, securely luted.
The first chamber is the furnace for fire, the second for ore, separated from the first by a grated partition, allowing the flame to pass through and play over the cinnabar. This ore-chamber, when filled, contains ten thousand pounds of cinnabar. The remaining chambers are for condensing the metal, communicating by square holes at the opposite corners; for instance, the right upper corner and lower left, and _vice versâ_, so that the vapour has to perform a spiral course in its transit through the condensers. Leaving the chambers, the vapour is conducted through a large wooden cistern, into which a shower of water continually falls, and thence through a long flue and tall chimney carried far away up the hillside.