sixty-six feet in diameter, which is employed to draw up the water. This water is afterwards conveyed along an aqueduct, nearly a mile and a half in length. The ore in this mine is not dug out, but blown up by gunpowder, an operation which is performed every day at noon, and is one of the most awful and tremendous that can be imagined.”

Our travellers arrived just at the moment of explosion ; and although Edward had been witness to the same sort of shock in the silver mines; he was absolutely petrified. ""Tis like subterraneous thunder, is it not, Sir?" said the astonished youth. "Or rather rapid discharges of vollies of artillery," replied the Doctor; " and the sensation of the trembling of the ground will give you an idea of that produced by an earthquake. See to what an height the stones are thrown above the level of the ground. But come, you must prepare for our descent; the concussion has perfectly subsided, and the men are already in attendance. This is rather an odd sensation," continued the Doctor, as the bucket descended into the dark and deep abyss beneath them. Nine minutes elapsed ere they reached the bottom, and then the view of the mine was awful and sublime in the highest degree. Whether fear or admiration was the prevailing sensation experienced by our travellers, they could scarcely define. The light of the day was very faintly ad mitted to these subterraneous regions; in many places it was absolutely lost, and flambeaus were kindled in its stead. Beams of wood were laid across some parts, from one side of the rock to the other, and on these the miners sat, employed in boring holes for the gunpowder, with the most perfect composure; although the least dizziness, or even a failure in preserving their equilibrium, must have made them lose their seat, and have dashed them against the rugged surface of the rock beneath: so powerful is the force of habit. The fragments, torn up by the late explosion, lay in vast heaps on all sides, and the whole scene was calculated to inspire a gloomy admiration. Our travellers remained for some time, exploring these frightful caverns, which afford employment for no less than 1300 workmen. The weather above was warm, but here ice covered the whole surface of the ground, and they found themselves surrounded with the cold of the most rigorous winter, amid darkness and caves of iron. In one of these, which ran a considerable way into the rock, half a dozen poor shivering wretches were warming them

selves round a charcoal fire, and eating the little scanty subsistence, arising from their miserable occupation. They started at perceiving such unexpected guests, and appeared pleased when the Doctor and Edward expressed a wish to dry their feet, which were quite wet from the melted ice, by their fire. They immediately made room for them; and a small donation from Edward, at his departure, was received by them with every mark of gratitude.

"Poor creatures," said Edward, as they slowly ascended, "what a wretched life! Do they live long, Sir, in these mines?"

DR. WALKER." The iron mines are not so pernicious as those of copper; but the most pernicious of all are the quicksilver mines: and those which are the least só, are the salt mines."

After their return to the "precincts of the cheerful day," they paid their respects to one of the owners of the forges in the neighbourhood, who hospitably entertained them, and entreated they would take up their abode with him that night. The offer was too inviting to be rejected; and they were not a little exhilarated at the sight of the cheerful fire, and plenteous good store, which was spread for their entertainment. When our travellers mentioned their intentions of visiting the mine at Fahlun, their host endeavoured to dissuade them from undertaking the expedition. "That mine is particularly unwholesome," said he; "and I think I could describe it to you sufficiently for your satisfaction.” Edward, however, expressed a particular wish to visit a mine so celebrated for its machinery, its copper, and, above all, as having been the asylum of the hero of the north, Gustavus Vasa. Their host therefore changed the subject, to that of the iron mine they had just visited. Throughout the whole extent of Sweden," said he, "the iron mines at present wrought, employ upwards of 25,000 persons, and yield annually upwards of 57,000 tons of metal. It has been calculated, that the furnaces and forges, which give to the iron the degree of perfection requisite before it can be used, consume annually 2,400,000 loads of charcoal. The peasants are chiefly employed in the manufacture of these metals; and as our travellers visited several of the forges, they had an opportunity of witnessing the astonishing dexterity, and perfect unconcern, with which these men pursue their hard, and apparently dangerous, employment. Habited in

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coarse linen frocks, they stand close to and hammer a bar of ore, the heat and refulgence of which were almost insupportable at ten feet distance; the sparks flying about them in every direction.

Dr. Walker was anxious his pupil should see the whole process of reducing the ore into iron, which is altogether a very curious process; and therefore the next day they inspected the different forges. It is first roasted in the open air for a considerable time; after which it is thrown into a furnace; and when reduced to fusion, it is poured into a mould of sand, about three yards in length. These pigs, as they are then called, are next put into a forge, heated to a prodigious degree; a large piece is then broken off with pinchers when red hot, and this is beat to a lesser size with hammers. It is again put into the fire, and from thence entirely finished, by being laid under an immense engine, resembling a hammer, which is turned by water, and which flattens the rude piece into a bar. Nothing can exceed the skill of the men employed in this concluding part of the operation, as the eye is the sole guide, and it requires an exquisite nicety and precision.

Having once more resumed their seat in their carriage, Dr. W. thus spoke upon the properties and nature of iron. "Iron," said the Doctor, "is the most universally diffused metal throughout nature. It is found in animals, in vegetables, and in almost all bodies. It is seldom found native, but combined with a great variety of substances. It is particularly distinguished by its magnetical properties; by its hard. ness and elasticity, by its ductility and the property of being welded, but it is very difficult to fuse. Iron soon rusts or oxydates, when exposed to the action of water. Iron filings agitated in water become oxydated, and assume the form of a black powder, called martial Ethiops. When iron ore is fused in large furnaces, it is made to flow into a kind of mould formed in sand. This first product, which is exceedingly brittle, and not at all malleable, is called cast iron, of which are formed stoves, pipes, cannon, and other articles. Cast, or crude iron, contains carbon and oxygen. The presence of the former appears from its coating the utensils employed in its fusion with plumbage or black lead, which contains nine-tenths of carbon, and one of iron."

EDWARD." I do not quite comprehend you, Sir. What is carbon, and what is oxygen?”

DR. WALKER. "Carbon and oxygen are two gasses. Our atmospheric air is composed of oxygen, nitrogen, and carbonic acid. Oxygen is that wholesome air, without which we could not breathe. This gas is absorbed by combustible bodies, and converts them into acids; hence its power of oxydizing, or rusting, certain metals. Gold, silver, and platina, will not become oxydated by exposure to the air; but in a very high temperature, that is to say, in a strong heat,oxyds are produced even from those metals. But to return to the air: nitrogen gas is unfit to maintain combustion, or support life; yet a small portion is absorbed in respiration. It is a little lighter than atmospheric air; when separated from it, is uninflammable, and one of the most general ele. ments of animal substances. Though nitrogen gas is of itself so noxious to animals, it answers an important end, when mixed with oxygen, in atmospheric air. Were it not for this large quantity of nitrogen in the atmosphere, the blood would flow too rapidly through the vessels, and would shorten the life of man. Carbonic acid gas is incombustible, and does not detonate with oxygen gas, and it is most noxious to animals. The atmospheric air, which is produced by this mixture, supports animal life, by giving out its caloric, or that substance which produces heat to the blood. The blood of the veins is purple, approaching to black, until it imbibes the atmospheric air through the lungs, when it becomes a brilliant red, pregnant with heat and motion. The loss of oxygen by respiration and combustion, is supplied by the leaves of trees and other vegetables, which in the day exude or breathe a large portion of oxygen gas; but at night they throw out azote or nitrogen gas: and hence they are unwholesome in a close chamber, while people sleep. They vegetate upon this impure air, and in return give out the oxygen. Any one or more of the simple substances, when united to a less quantity of oxygen gas than is necessary to form an acid, produces what is called oxyd: hence the words carbon and oxygen, when applied to metals, means, that they contain properties partaking of the nature of those gasses, or else that they are capable of being acted upon by them."

EDWARD.

"You mentioned simple substances, what am

I to understand by that expression?"

DR. WALKER." Simple substances are those bodies, which have never yet been decomposed, nor formed by art.