In South America, the Chilian lead mine of Mina Grande, near Coquimbo, is renowned for its extreme richness, and Brazil has considerable veins of galena, in the province of Minas Geraes; but probably the United States of North America (Wisconsin, Arkansas, Iowa, Illinois), possess the largest galena deposits in the world. In Wisconsin, they extend all over a vast territory of more than 4,000 square miles. As yet the works are conducted in the most negligent manner, by a crowd of adventurers. In winter, when the air in the pits is more salubrious, and agricultural labour ceases, needy farmers, bankrupt traders, and thriftless artisans flock from all parts to the lead country for the purpose of repairing their broken fortunes. In summer when malaria renders the pits extremely unhealthy, this nomadic population melts away like chaff before the wind. Yet, in spite of the rough mode of extraction which prevails in the American lead country, the mines of Iowa, Wisconsin, and Illinois yielded about 20,000 tons of lead in 1866, and their produce is constantly increasing. In all lead mines, the galena often occurs in pieces so large that they do not require to be separated from the veinstone by the processes of stamping and washing. They are then called _pure ores_, and the most simple preparation is sufficient to prepare them for the smelting furnace. When the ore has been picked and so far prepared, it is first roasted or heated in a reverberatory furnace, an operation which causes the oxygen of the air to combine with the two elementary bodies of which galena is composed. After undergoing this chemical change, the ore is now mixed with coke, charcoal, or peat, and reduced by smelting in a small blast furnace of a peculiar kind. Under the influence of heat, the carbon of the coal, uniting with the oxygen of the ore, flies off in the form of carbonic acid gas, while the metallic lead, which in the finer ores amounts to 70 or 80 per cent., sinks to the bottom of the furnace. Almost all the varieties of galena contain a greater or less proportion of silver, which it is often found worth while to separate from them. This process is at present effected according to a most ingenious method, founded on the circumstance first noticed in the year 1829, by the late H. L. Pattinson, of Newcastle-on-Tyne, that when lead containing silver is melted in a suitable vessel, afterwards slowly allowed to cool, and at the same time kept constantly stirred at a certain temperature near the melting point of lead, crystals begin to form. These, as rapidly as they are produced, sink to the bottom, and on being removed are found to contain much less silver than the lead originally melted. The still fluid portion, from which the crystals have been removed, will at the same time be proportionally enriched. By repeated meltings and crystallisations in a series of cast-iron pots with fire-places beneath, the workman is thus able to deprive almost