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Remarkable Ductility and Extensibility of Gold

-Gold is the most ductile, as well as the most malleable, of all metals. According to Cronstedt, one grain of it may be stretched out so as to cover 98 Swedish ells, equal to 63.66 English yards of silver wire; but Wallerius asserts, that a grain may be stretched out in such a manner, as to cover 500 ells of wire. At any rate, the extension is prodigious; for, according to the least of the calculations, the millionth part of a grain of gold may be made visible to the naked eye. Nor is its malleability inferior to its ductility. Boyle, quoted by Apligny, in his treatise on Colours, says, that one grain and a half of gold may be beaten into 50 leaves of an inch square, which, if intersected by parallel lines drawn at right angles to each other, and distant only the hundredth part of an inch from each other, will produce twenty-five millions of little squares, each very easily discernible by the naked eye. Mr. Magellan tells us, that its surface may be extended by the hammer 159,092 times. " I am informed, (says he) by an intelligent goldbeater in England, that the finest gold leaf is that made in new skins, and must have an alloy of three grains of copper to the ounce of pure gold, or else it would be too soft to pass over the irregularities of the skins. He affirms, that 80 books, or 2000 leaves of gold, each leaf containing 10.89 square inches, weigh less than 384 grains. Each book, therefore, of 25 leaves, or 272.25 inches, weighs less than 4.8 grains; so that each grain of the metal will produce about 57 square inches of gold leaf." From further calculation it appears, that the thickness of these leaves is less than the 282,000th part of an inch; and that 16 ounces of gold would be sufficient to gild a silver wire, equal in length to the whole circumference of the globe we inhabit!

PIN-MAKING.-Though pins are apparently simple, their manufacture is not a little curious and complex. When the brass wire, of which the pins are formed, is first received at the manufactory, it is generally too thick for the purpose of being cut into pins. The first operation, therefore, is that of winding it off from one wheel to another with great velocity, and causing it to pass between the two, through a circle in a piece of iron of smaller diameter. The wire being thus reduced to its proper dimensions, is straightened by drawing it between iron pins, fixed in a board in a zigzag manner, but so as to leave a straight line between them: afterwards it is cut into lengths of three or tour yards, and then into smaller ones, every length being sufficient to make six pins. Each end of these is ground to a point, which was performed, (where these observations were made,) by boys, who sat each with two small grinding stones before him, turned by a wheel. Taking up a handful, he applied the ends to the coarsest of the two stones, being careful at the same time to keep each piece moving round between his fingers, so that the points may not become flat: he then gives them a smoother and sharper point by applying them to the other stone, and by that means a lad of twelve or fourteen years of age, is able to point about sixteen thousand pins in an hour. When the wire is thus pointed, a pin is taken off at each end, and this is repeated till it is cut into six pieces . The next operation is, that of forming the heads, or, as they term it, head-spinning, which is done by means of a spinning -wheel, one piece of wire being thus with astonishing rapidity wound round another, and the interior one being drawn out, leaves a hollow tube between the cir- : it is then cut with shears, every two circumvolutions, or turns of the wire, forming one head; these are softened by throwing them into iron pans, and placing them in a furnace till they are red hot. As soon as they are cold, placing they are distributed to children, who sit with hammers and anvils before them, and catching one at the extremity, they apply them immediately to the anvil and hammer, and by a motion or two of the foot, the top and the head are fixed together in much less time than it can be described, and with a dexterity only to be acquired by practice. The pin is now finished as to its form, but still it is merely brass; it is therefore thrown into a copper containing a solution of tin and the lees of wine. Here it remains for some time, and, when taken out, assumes a white, though dull appearance: in order therefore to give it a polish, it is put into a tub containing a quantity of bran, which is set in motion by turning a shaft that runs through its centre, and thus, by means of friction, it becomes perfectly bright. The pin being complete, nothing remains but to separate it from the bran, which is perfectly similar to the winnowing of corn, the bran flying off, and leaving the pin behind it for immediate sale.