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calaminaris, which contains the zinc, and by which it is rendered harder, and becomes of a yellow colour. It is rather lighter, harder, and more sonorous than pure copper, and melts easier; but, if heated even a little, is apt to crack and fall in pieces under the hammer; for which reason, it is generally cast into the form required, and polished afterwards. The beauty of its colour, and being less subject to rust than copper, recommend it for the purposes of many domestic utensils. A gold colour may be imparted to brass, by first burning it, then dissolving it in aquafortis, and lastly reducing it to its metalline state or it may be whitened by heating it red hot, and quenching it with water distilled from sal ammoniac and chalk.
CHARLES. The Corinthian brass was highly valued among the ancients: was that merely a mixture of copper and calamine?
It is certain that it was a metallic composition of great beauty, and prized but little below gold: but many doubt the relation of Pliny, who says that it was a mixture of metals, occasioned by the con
flagration of Corinth, when that city was taken by L. Mummius, 146 years before Christ.
SOPHIA. Bell-metal bears some resemblance to brass. Is that also a composition?
MR. HARCOURT. It is composed of a due proportion of copper and tin. In the metal of which cannon is made, the copper is mixed with various ingredients of a coarser nature, to make it run close, and founder well. Before we dismiss the subject of copper, it may be proper to specify the uses to which it is most commonly applied.
CHARLES. As I was passing by a coppersmith's, a little while since, I stood some time to observe the men at work: they were making large vessels, for the purpose of boilers, to which, they told me, copper was particularly adapted, from the ease with which it could be hammered out to a proper thinness. There was also a vast number of sheets of copper, prepared for covering the roofs of houses, and sheathing of ships: by this contrivance, their holds are defended from worms, and the smoothness of its surface contributes to the swiftness of their sailing.
CECILIA. Copper is likewise essential to the engraver. The finest prints are engraved upon sheets of that metal.
MRS. HARCOURT. Perhaps we may enlarge upon this topic at some future opportunity. It is now time to turn our thoughts upon iron, which is the hardest of all metals, and the most extensively useful of any of them: next to gold, it has the greatest tenacity of parts, or difficulty of being broken; is very elastic; and requires a great degree of heat to put it into a state of fusion. The hardness, brittleness, and capacity of yielding to the hammer, varies in iron, according to the nature of the ore from which it is obtained, and the operation it has undergone. Cast-iron is that which is run from the ore, and, from a mixture of crude earth, is so hard as generally to resist the file or the chisel: it is likewise brittle and unmalleable, in this state; but is rendered tough by the operation of forging, which is performed by heating it red hot, and then striking it with large hammers, which force a quantity of vitreous matter out of it. Steel is iron combined with a small proportion
of charcoal: it is produced by fusing bars of the purest iron in an earthen crucible, with a cement of charcoal, wood-ashes, and different animal substances; such as bones, horns, skins, or hair. The metal, in consequence of this change, acquires a more compact and close-grained texture, and becomes harder, more elastic and tenacious, as well as more fusible. Different degrees of elasticity and brittleness may be given to steel, according to the uses for which it is designed.
CHARLES. Papa's sword affords specimens of both qualities: the fine polished handle is very brittle, as he observed when he broke it by hitting it against a chair; and the blade is so flexible, it will bend almost double without breaking.
MR. HARCOURT. Flexibility is an essential requisite in a sword; for a soldier would presently be exposed to the power of his enemy, whose weapon was easily broken. Damascus and Toledo are famous for manufacturing the best swords.
SOPHIA. Without the elasticity of steel, we should be deprived of the accommodation
of watches. I think they are moved by steel springs.
MRS. HARCOURT. Steel watch-springs are chiefly made at Geneva, by children.
AUGUSTA. Pray, what method is taken to give them that blue colour, of which I have frequently seen them.
MR. HARCOURT. Polished plates of steel, put upon a gentle charcoal fire, acquire different colours on their surfaces, and pass through several shades, according to the degrees of heat; becoming first white, then yellow, orange, purple, violet, and lastly blue. The hardness of steel renders it capable of receiving a sharp edge, which adapts it peculiarly for the blades of all instruments for cutting, such as knives, razors, scissors, &c.
CECILIA. Ornamental works of polished steel are extremely beautiful; their brilliancy is exquisite; and I have heard that the workmanship raises them in value to nearly the equivalent of silver and gold.
MR. HARCOURT. Steel is most suitable to all purposes of nicety, where polish or flexibility is requisite; but iron is applicable to