A tunnel has been formed at the bottom of the mine through which the waters flow after they have performed their task, which also carries away the crushed granite, while the heavier metalliferous substances are precipitated into the troughs. Neither engine-house nor chimneys such as are seen in other mines are visible, while every detail of the work is exposed to view—indeed, the huge basin has the appearance of a mine completely turned inside out.
There are two methods of smelting tin. By the most common, the ore, mixed with culm, is subjected to heat on the hearth of a reverberating furnace, when ordinary coal is employed. By the other method, the ore is fused in a blast furnace, when wood fuel or charcoal is used. The tin when smelted runs off from the furnace into an open receiver, from which it flows into a large vessel, where it is allowed to settle. After the scoriae have been skimmed off, the upper and purer portion of the mass is refined, and the lower part re-melted.
Chapter Five.
The Metals found in Mines.
The chief object of the travellers was to inquire into the mode in which mines in different countries are worked, the causes of accidents, and the best method of preventing them. Their knowledge was superior to that which most of our readers are likely to possess, and it will be necessary, in order to understand their proceedings, to glance at the mining districts of the world, and to describe some of the principal mines among them.
No country possesses, within the same area, so large an amount of varied mineral wealth as Great Britain. Besides the seventeen coal districts of Great Britain, we find in Scotland numerous lead mines in the clay slate mountains on the borders of Lanarkshire and Dumfriesshire. In the north of England, with Alston Moor as the centre, along the borders of Northumberland, Cumberland, Westmoreland, and Durham, are extensive veins of lead. Cumberland, the north of Wales, and the Isle of Anglesey produce copper ore, as also mines of lead and magnesia, with many other metals,—zinc, arsenic, cobalt, and bismuth. Iron in large quantities is found in South Wales, South Staffordshire, and in the Scottish coal-fields, where the ironstone appears in abundance alternating with layers of coal and other strata, and is generally won from the same pit as that from which the coal is extracted.
Besides coal, Ireland contains mines of copper and lead, found in the slate and limestone ranges, contiguous to the sea coast. Crossing from thence to Spain, we arrive in a country rich in mines, though, owing to its distracted state, for many years greatly neglected. Here lead is found in large quantities in the mountain chains.
Quicksilver is abundant from extensive veins of cinnabar in the province of Mancha. In Galicia tin has been produced from very early times. Iron ore is very abundant, and silver mines, for many centuries abandoned, are now again being reworked. Gold was at one period discovered in large quantities, but is supposed to be almost exhausted.