8. Black sulphuret of silver; is blackish, brittle, cellular, affording globules of silver at the blowpipe. It is found only in certain mines, at Allémont, Freyberg; more abundantly in the silver mines of Peru and Mexico. The Spaniards call it negrillo.
9. Chloride of silver, or horn silver.—In consequence of its semi-transparent aspect, its yellowish or greenish colour, and such softness that it may be cut with the nail, this ore has been compared to horn, and may be easily recognised. It melts at the flame of a candle, and may be reduced when heated along with iron or black flux, which are distinctive characters. It is seldom crystallized; but occurs chiefly in irregular forms, sometimes covering the native silver as with a thick crust, as in Peru and Mexico. Its density is only 4·74.
Chloride of silver sometimes contains 60 or 70 per cent. of clay; and is then called butter-milk ore, by the German miners. The blowpipe causes globules of silver to sweat out of it. This ore is rather rare. It occurs in the mines of Potosi, of Annaberg, Freyberg, Allémont, Schlangenberg, in Siberia, &c.
10. Carbonate of silver, a species little known, has been found hitherto only in the mine of S. Wenceslas, near Wolfache.
Table of the Quantities of Silver brought into the Market every year, on an average, from 1790 to 1802.
| Old Continent. | Lbs. Avoird. | New Continent. | Lbs. Avoird. | ||
|---|---|---|---|---|---|
| ASIA. | |||||
| Siberia | 38,500 | Central America | 1,320,000 | ||
| EUROPE. | South America | 605,000 | |||
| Hungary | 44,000 | ||||
| Austrian States | 11,000 | ||||
| Hartz and Hessia | 11,000 | ||||
| Saxony | 22,000 | ||||
| Norway | 22,000 | ||||
| Sweden | - | 11,000 | |||
| France | |||||
| Spain | |||||
| Total of the Old Continent | 159,500 | Total of the New Continent | 1,925,000 | ||
Thus the New Continent furnished twelve times more silver than the Old. For more detailed [statistics] of silver, see the end of the article.
The following is Mr. Ward’s description of the treatment of silver ores in Mexico:—
“After returning from San Augustin,” says he, “I passed the whole of the afternoon at the hacienda (metallurgic works) of Salgado, in which the ores of the Valenciana mine are reduced. The hacienda, of which a representation is given below, [fig. 1001.] contains forty-two crushing-mills, called arrastres, and thirty-six stampers. The ore, on being extracted from the mine, is placed in the hands of the pepenadores, men and women, who break all the larger pieces with hammers, and after rejecting those in which no metallic particles are contained, divide the rest into three classes” (inferior, middling, and rich). “These are submitted to the action of the morteros (stamps), one of which, of eight stampers, is capable of reducing to powder ten cargas of ore (each of 350 lbs.) in twenty-four hours. This powder not being thought sufficiently fine for the quicksilver to act upon with proper effect, it is transferred from the morteros to the arrastres (crushing-mills, see [wood-cut]), in which water is used. Each of these reduces to a fine impalpable metalliferous mud, six quintals (600 lbs.) of powder in 24 hours. At Guanajuato, where water-power cannot be obtained, the arrastres are worked by mules (see [fig. 1001.]), which are kept constantly in motion at a slow pace, and are changed every 6 hours. The grinding-stones, as well as the sides and bottom of the mill itself, are composed of granite; four blocks of which revolve in each crushing-mill, attached to cross-bars of wood. This part of the operation is thought of great importance, for it is upon the perfection of the grinding that the saving of the quicksilver is supposed in a great measure to depend, in the subsequent amalgamation. The grinding is performed usually in a covered shed or gallery which in a large hacienda, like Salgado, from the number of arrastres at work at the same time, is necessarily of considerable extent.”