ADULTERATION OF COIN. This has been accounted among all nations, both in ancient and modern times a very grave offence, and punishable by death in several ways. It was formerly considered as treason in Great Britain, and ri-
Adulterine gorously punished with death; but in the amelioration of our criminal code by Lord John Russell's act (Will. IV., c. 34, Vict. 1), the punishment has been commuted to transportation for any period not less than seven years, or by imprisonment for not more than four years, at the discretion of the judge.
The specific gravity of pure gold = 19.30; standard gold = 18.88; pure silver = 10.51; standard silver = 10.34. The proportion of alloy in the gold and silver coin of Britain is copper, which gives durability. A genuine coin, unless it be cracked, is quite sonorous; yet even this quality is not an invariable test for counterfeit money. Much false coin is in circulation, especially in the metropolis, a statement confirmed by its very frequent reception as change. Besides the frauds by clipping, filing, casing, electroplating, &c. the debasement of coin has been effected by boring the edge of a piece, and plugging the cavity with inferior metal; in this manner has platinum been inserted in gold. Another method has been practised by sawing a gold piece laterally, and skilfully filling the centre with platinum; a fraud which cutting alone could detect.
To ascertain the adulteration of silver and gold coin by excess of copper, the following processes will suffice: dissolve a given weight of the silver in nitric acid, and precipitate by a solution of common salt; dry, and weigh the precipitate, which is the chloride of silver, and contains 75.5 per cent. of the metal; or it may be reduced on charcoal before the blowpipe, when a button of pure silver will be obtained, by weighing which, the proportions of silver and of copper will be known. Silver coin is very frequently imitated by some white alloy, generally of tin, antimony, and lead: it may be known by its pliancy and dull appearance, or it may be tested for silver, as described above. German silver, a beautiful imitation of silver by nickel and copper, may be detected by its deficient specific gravity, and its emitting, when briskly rubbed, a faint, coppery odour; or by dissolving it in nitric acid, and adding a solution of common salt, when it will give no precipitate. The amount of alloy in gold may readily be ascertained, for ordinary purposes, by the streak on touchstone, and comparing that with the streak of the gold needles made for the purpose; or more nicely by this process: file off a given weight of the gold, and dissolve in aqua regia, then precipitate the gold by immersing in the solution a plate of silver or copper; or more quickly, by weak galvanic action; or the gold may be thrown down by addition of an alkaline solution, or by adding the muriate of tin, which throws down the purple powder of Cassius, from which the quantity of gold may be easily ascertained, by oxidating with the blowpipe a given weight of the powder, and so obtaining a button of pure gold.
The purity of copper is ascertained by dissolving a given weight in any of the mineral acids, and obtaining copper of cementation by immersing a plate of iron or zinc in the solution; or by decomposing the salt of copper by charcoal, alkali, and heat, in the usual way. See CHEMISTRY. It may be noticed as a curious fact, that the copper coinage of Will. IV. was found to contain gold, from which discovery these coins speedily became scarce.