Tin is found in Cornwall in larger quantities than in any other part of the world. It is generally discovered in the alluvial soil of low grounds, where it is known as stream tin, because it has been washed by the agency of water from the rocks in which it was originally embedded mixed with sand and gravel. Tin is also found in the island of Banca, in the Indian Archipelago, in Bohemia and Saxony, Chili and Mexico. Mercury is a rare metal. The richest mines are at Almaden, a small town of La Mancha, in Spain. It is also found in Austria, China, and Peru, and a few other places. It is sometimes found in globules, but it is generally procured from one of its ores, cinnabar, a sulphate of the metal, of a red colour, and indeed identical with the richly prepared paint vermilion. A thousand workmen are employed in the Spanish mines, above or under ground. It freezes at an exceedingly low temperature, and was found solid during midwinter by the traveller Pallas. Of the other metals, some used as medicines, or pigments, or to form alloys, we have not time now to speak. CHAPTER SIX. SALT AND QUICKSILVER MINES. The object of the travellers was not only to inspect coal mines, but to view the wonders of the subterranean world. It is impossible to do more than give a very brief account of the places they visited. They had found their way to the Carpathian Mountains, in order to visit the salt mines of Wieliczka, a small town to the south of Cracow. The valley in which the mine is situated is fruitful and picturesque. Descending by a staircase of thirty feet or so, through a bed of clay, they arrived at the commencement of the level galleries, which branch off in all directions. Overhead was a ceiling of solid salt, under foot a floor of salt, and on either side grey walls of salt, sparkling here and there with minute crystals. The guide led them on through a bewildering maze of galleries. Now they entered a grand hall, now descended by staircases to another series of vaulted chambers. On every side was solid salt, except where stout piers of hewn timber had been built up to support the roof, or wooden bridges had been thrown over some vast chasm. As they descended, the air became dry and agreeable, and the saline walls more pure and brilliant. One hall, 108 feet in length, resembled a Grecian theatre, the places where the blocks had been taken out in regular layers representing seats for the spectators. Here and there were gangs of workmen, some labouring at the solid floor, others trundling wheel-barrows full of cubes of salt.