brook, and in the sands and valleys over which torrents have passed: and the supplies from this source must have been far more plentiful in early times than at present, when the superficial parts of the earth have almost everywhere been ransacked for the precious substances. The ancient writers frequently speak of rivers famous for the gold, silver, and copper, which they rolled down in their waters. These metals are also found in other situations, in grains or lumps; and in whichever of these forms exhibited, the metal would have been generally so pure and unmixed as to need none of those elaborate processes of smelting and refining, which ores taken from the mine generally require. The early stock of metal which we find existing in the hands of men, might therefore have been obtained with comparatively small labour or difficulty. However, it appears that men did, at a very early period, acquire the art of extracting metal from the mine, and of refining the ore. These processes are mentioned distinctly in the very ancient book of Job. (Chap. xxviii.) The metals must have been known for some time before the art was discovered of forging them into shapes proper for their designed uses. Goguet thinks that people had not at first any other way of shaping metals than by casting them in moulds. Strabo mentions a nation that made use of cast copper, not knowing how to forge it; and there are barbarous nations no less ignorant at this day. It would soon be observed, however, that all metals, except lead and tin, became flexible and soft when in the fire; and this would readily suggest the idea of working them, when in a state of heat, into the various forms they were desired to bear. This art must have been very ancient knives, swords, and shears, occur to our notice in the history of the Patriarchs; and, from the ornaments of silver and gold which are mentioned in the same history, it is evident that men had learned how to execute, in gold and silver, works of considerable delicacy and exactness. The great degree of perfection which the arts of working in metal had reached, is still more strongly evinced in the account of the works for the tabernacle. The skill which must have been necessary to execute the works described here, very clearly intimates that the discovery of the art could not have been very recently

made. Goguet omits to observe that the fact of the precious metals having, as early as the times of the Patriarchs, become the signs of property, (Gen. xiii. 2,) the media of traffic, and objects of valuable ornament, would alone demonstrate the antiquity of their use. For there can be no question that much time was taken before an estimate of the relative value of the metals could be formed, and that the most precious was first applied to common and mean uses. There was an Egyptian tradition that the art of working gold and copper being discovered in the Thebais, arms were first made to exterminate the beasts of prey, and then tools to cultivate the ground. These were the most obvious purposes to which metals would be applied, whatever metals were first discovered; and accordingly we find instances, in modern as well as ancient times, of gold and silver being applied to the commonest uses of daily life, where the inferior metals were not known. Knight's Illustrated Commentary.

USEFUL COUNSEL TO THE YOUNG.

GUN-COTTON; AND ITS EXPLOSIVE POWER.

A SHORT time ago we were favoured with the opportunity of hearing an address delivered to a society of medical students in the metropolis, by their President, on the occasion of their first meeting for the season. We were ourselves highly gratified; and we believe that our readers will be glad to have repeated to them some of the observations that were made, both by the President and Vice-President. The students were impressively reminded of the motto of their collegiate seal, and earnestly advised always to conduct themselves as well as their studies in accordance with its important suggestions. It is a motto which we hope the readers of The Youth's Instructer" will take as their own. In reference to its principles the articles for their monthly perusal are always sought to be prepared; and with the same reference we trust they will always be read,-" SANCTE SAPIENTER: with holiness and wisdom. Studies so pursued, connected with a life so governed, will not only conduce to their present profit

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and happiness, but to the final attainment and everlasting possession of the great end of their being.

The students were particularly recommended to observe, and to reason. Many things, they were rightly told, might pass before them, and yet, either from inattention, or from some strong pre-occupation of the mind, no notice be taken of them. The speaker said that he recollected, that once, a large eclipse of the sun, which he had much wished to observe, actually took place while he was walking up and down the streets, thinking of the business in which he was engaged, so that the time of its duration passed over without any reference to it. He was all the while in the very presence of the eclipse, but, because he did not think of it, he did not see it.

But the most stress was laid on the second recommendation : not only see,—be aware of the existence of the fact, and its presence before you, but reason upon it; investigate it; ask, as it were, whence it comes, and whither it goes. The speaker illustrated the importance of this advice by saying that two of his friends had been, some years ago, on the very verge of the discovery of two of the most important modern additions to science, electro-metallurgy, and gun-cotton. One of them had to attend, professionally, to the decomposition of metallic salts by means of galvanism; and he noticed that if there were even the impression of the end of his thumb on the substance which received the deposited metal, when the metal was removed, a corresponding impression was found upon it. He noticed it, but that was all. An experiment or two, conducted for the purpose, would at once have led him to the discovery which has of late excited so much attention. He did not make them; and thus, though so near the land that he might have jumped ashore from his boat, and planted his standard as first discoverer, he turned away the boat, and left the honour for another.

The speaker had another friend, who had occasionally to try the effect of acid on silk in discharging colours or stains. He held it sometimes to the fire to dry it, and, on two or three occasions, it came in contact with the fire, and at once exploded, leaving no remainder. Here was, substantially, the

same fact that the gun-cotton has since exhibited; but the accident was not turned into an experiment, followed up by the requisite inquiry, and thus the discovery was delayed.

If thoughtlessness may produce such fearful results in man's moral relations; if neglect of salvation is connected with such heavy guilt, and followed by such awful punishment; still, we find in all this nothing which is at all contrary to, or even inconsistent with, “the established course of nature," as Bishop Butler terms it in his great work. On the contrary, we see in this point the same analogy existing which he has so admirably pointed out in many others. Not only heedlessness, but want of attention, may occasion the absence of much good; the presence of much evil. It is so in God's natural, why should it not be so in his moral, government?

These last remarks, however, are only a digression, though, we hope, neither useless nor unimportant. Resuming the thread of our observations, we proceed to say that the speaker, having adverted to "gun-cotton," held up to the view of the meeting a sheet of writing-paper, on which was spread a circle of this material. Applying a light to it, explosion in a bright flame instantly took place, leaving the paper clear and unsoiled. Gunpowder could not have exploded more immediately, nor more completely. Leaving the general counsel to the serious consideration of our readers, we shall just add a statement which we have very recently met with, illustrative of the wonderful power of this last-mentioned material.

A series of experiments have lately been employed to test the efficacy of gun-cotton in blasting, as compared with gunpowder, in the Standedge tunnel, on the Manchester and Huddersfield railway, through the great Yorkshire chain of hills, lying between those towns. This tunnel, when completed, will be the longest that has yet been made. The rocks are more than four hundred and fifty feet below the surface of the mountain, and consist entirely of close-grained quartz. Some idea of its compactness may be formed when it is said, that, in one hundred and ten yards of this tunnel now completed, in the whole length not a single fissure or joint is to be found. A better test of comparative power, therefore, could not have been devised. First, a rough estimate was

made with fire-arms, and it was found that a charge of the prepared cotton produced on a wooden target the same effect as one of gunpowder of six times the weight. Holes were drilled in the stone of two inches, one and a half inches, and one and a quarter inches in diameter, and charges of guncotton, varying from one-sixth to one-third the weight of powder usually employed in blasting, were put into them. The quantities varied from ten ounces in the larger, to six ounces in the smaller tubes. There were twelve, enumerated as 1, 2, and so on; Nos. 4 and 11 being charged with gunpowder. It was thought that Nos. 2, 7, and 12, would afford the most striking results in relation to the object sought. No. 2 was charged with ten ounces of cotton, and produced effects far exceeding expectation. No. 7 was charged with one ounce and a quarter of cotton, and did as much execution as six ounces of gunpowder would have done. Nos. 11 and 12 were the crowning experiments. No. 12 was charged with sixteen ounces of cotton, against three pounds four ounces of gunpowder in No. 11. These exceeded anything the miners had ever witnessed. The gun-cotton exploded first, and threw against the side of the heading, and broke into nine pieces, two hundred and twenty cubic feet of rock, or about fifteen tons weight. This shot, from its proximity to No. 11, was supposed to have assisted it materially. It moved away two hundred and twenty-four cubic feet of rock, or about sixteen and a half tons.

How wonderful are the powers which feeble man is able to employ! Without any power but his own,-just with fingers and nails,-what could he do against such a mass of rock? With the simple machines of hammer and chisel, he could do much more; but only fancy the attempt to cut a tunnel through this mountain of rock, (some of our readers know the range, spreading from the Peak of Derbyshire far away towards Scotland,) only by setting men to chip it by repeated hammerstrokes! But he learns how to compose an exploding material, and how to employ it. He finds that the chemical mixture of substances containing certain elements abundantly existing in nature, will, when set on fire, explode with a force of expansion which the solid rock cannot resist. In one form