{109} The moliendas, or crushing-mills (arrastres, as called at some mines), employed for the purpose of grinding the [p183] ores, are somewhat singular machines. A circular (or rather annular) cistern of some twenty or thirty feet in diameter is dug in the earth, and the sides as well as the bottom are lined with hewn stone of the hardest quality. Transversely through an upright post which turns upon its axis in the centre of the plan, passes a shaft of wood, at each end of which are attached by cords one or two grinding-stones with smooth flat surfaces, which are dragged (by mules fastened to the extremities of the shaft) slowly around upon the bottom of the cistern, into which the ore is thrown after being pounded into small pieces. It is here ground, with the addition of water, into an impalpable mortar, by the constant friction of the dragging stones against the sides and bottom of the cistern. A suitable quantity of quicksilver is perfectly mixed with the mortar; to which are added some muriates, sulphates, and other chemical substances, to facilitate the amalgamation. The compound is then piled up in small heaps, and not disturbed again until this process is supposed to be complete, when it is transferred to the washing-machine. Those I have observed are very simple, consisting of a kind of stone tub, into which a stream of water is made to flow constantly, so as to carry off all the lighter matter, which is kept stirred up by an upright studded with pegs, that revolves in the centre, while the amalgamated metals sink {110} to the bottom. Most of the quicksilver is then pressed out, and the silver submitted to a burning process, by which the remaining portion of mercury is expelled.
The silver which is taken from the furnace, generally contains an intermixture of gold, averaging from ten to thirty per cent.; but what is extracted by amalgamation is mostly separated in the washing. While in a liquid state, the gold, from its greater specific gravity, mostly settles to the bottom: yet it usually retains a considerable alloy of silver. The [p184] compound is distinguished by the name of oroche. The main portion of the silver generally retains too little gold to make it worth separating.
Every species of silver is moulded into barras or ingots, weighing from fifty to eighty pounds each, and usually worth between one and two thousand dollars. These are assayed by an authorized agent of the government, and stamped with their weight and character, which enables the holder to calculate their value by a very simple rule. When the bullion is thus stamped, it constitutes a species of currency, which is much safer for remittances than coin. In case of robbery, the barras are easily identified, provided the robbers have not had time to mould them into some other form. For this reason, people of wealth frequently lay up their funds in ingots; and the cellars of some of the ricos of the South, are often found teeming with large quantities of them, presenting the appearance of a winter's supply of firewood.
{111} As the charge for parting the gold and silver at the Mexican mints, is generally from one to two dollars, and coinage about fifty cents, per pound, this assayed bullion yields a profit upon its current value of nearly ten per cent. at the United States Mint; but, if unassayed, it generally produces an advance of about double that amount upon the usual cost at the mines. The exportation of bullion, however, is prohibited, except by special license from the general government. Still a large quantity is exported in this way, and considerable amounts smuggled out through some of the ports.
A constant and often profitable business in the 'silver trade' is carried on at these mines. As the miners rarely fail being in need of ready money, they are generally obliged to sell their bullion for coin, and that often at a great sacrifice, so as to procure available means to prosecute their mining [p185] operations. To profit by this trade, as is already mentioned, was a principal object of my present visit. Having concluded my business transactions, and partially gratified my curiosity, I returned to Chihuahua, where I arrived, November 24, 1835, without being molested either by robbers or Indians, though the route is sometimes infested by both these classes of independent gentry.
But, as it is now high time I should put an end to this digression, I will once more resume my narrative, where it was interrupted at my arrival in Chihuahua, on the first of October, 1839.
{112} It is usual for each trader, upon his arrival in that city, to engage a store-room, and to open and exhibit his goods, as well for the purpose of disposing of them at wholesale as retail. His most profitable custom is that of the petty country merchants from the surrounding villages. Some traders, it is true, continue in the retail business for a season or more, yet the greater portion are transient dealers, selling off at wholesale as soon as a fair bargain is offered.
The usual mode of selling by the lot in Chihuahua is somewhat singular. All such cottons as calicoes and other prints, bleached, brown and blue domestics both plain and twilled, stripes, checks, etc., are rated at two or three reales[125] per vara, without the least reference to quality or cost, and the 'general assortment' at 60 to 100 per cent. upon the bills of cost, according to the demand. The varage is [p186] usually estimated by adding eight per cent. to the yardage, but the vara being thirty-three inches (nearly), the actual difference is more than nine. In these sales, cloths—{113} indeed all measurable goods, except ribands and the like, sometimes enter at the varage rate. I have heard of some still more curious contracts in these measurement sales, particularly in Santa Fé, during the early periods of the American trade. Everything was sometimes rated by the vara—not only all textures, but even hats, cutlery, trinkets, and so on! In such cases, very singular disputes would frequently arise as to the mode of measuring some particular articles: for instance, whether pieces of riband should be measured in bulk, or unrolled, and yard by yard; looking-glasses, cross or lengthwise; pocket-knives, shut or open; writing-paper, in the ream, in the quire, or by the single sheet; and then, whether the longer or shorter way of the paper; and so of many others.
Before the end of October, 1839, I had an opportunity of selling out my stock of goods to a couple of English merchants, which relieved me from the delays, to say nothing of the inconveniences attending a retail trade: such, for instance, as the accumulation of copper coin, which forms almost the exclusive currency in petty dealings. Some thousands of dollars' worth are frequently accumulated upon the hands of the merchant in this way, and as the copper of one department is worthless in another, except for its intrinsic value, which is seldom more than ten per cent. of the nominal value, the holders are subjected to a great deal of trouble and annoyance.