The subject of numismatology has been treated, either partially or at large, by various authors, such as Vail :ant, Beauvais, Le Blanc, Banduri, Beger, Hancarville, Cooke, Sestini, Pinkerton, and others, to whose works nre shall refer at the end of this article. But t4e most distinguished name in this science is undoubtedly that of Eckhel of Vienna, a man of profound learning and excellent judgment, who first reduced this branch of knowledge into systematic order, and whose methodical arrangement we propose to adopt, with sonte slight de viations, in the sequel.
Before proceeding, however, to the classification and description of ancient coins, it appears necessary, for the better understanding of the subject, that we should make some preliminary observations on the metals or which they were composed, their weight, value, and size, their names and denominations, the languages in scribed upon them, as well as upon the various methods of forging and imitating these interesting remains of an tiquity.
The materials of which the ancient coins were com posed were, as in modern times, gold, silver, and the various modifications of copper. The laws of Lycur gus also make mention of iron coins being introduced among the Spartans ; and the sante has been said or B‘ zantium. But experience has not confirmed this infor mation; and even if it had been the case, it is not likely that coins of a metal so liable to be destroyed by rust, as iron, should have been preserved to modern times. Ali that remains to us of the ancient coinage, is composed of the three metals above mentioned ; and that these were the only materials used, appears highly probable from numerous specitnens of the coins of the emperor Augustus, on the reverse of which the triumviri, who had the superintendance of the mint, used to denominate themselves: IIIVIR.A.A.A.F.F. that is, Ala.° virgento viere Flando Feriundo. (Plate CCCCXX. Fig. 2.) Among the Romans and Greeks, the gold and silver was of the finest quality. Some important changes, how ever, took place in the Roman silver coinage : lor its in trinsic quality became depreciated in proportion to the decline of the resources of the empire. From the time cf the emperor Severus, the quantity of base alloy was con siderable ; and afterwards the copper came to predominate over the silver. These coins, therefore, were called numi cerosi, or incactiles, on account of the great admix ture of copper. From the time of Claudius Gothicus, to that of Dioclesian, silver coins arc exceedingly rare ; but it was common to wash over the brass or copper coins with silver.
The ancient brass coins consist partly of pure copper, and partly of a mixture of that with other metals. For a long period, antiquaries were accustomed to talk of coins of Corinthian brass ; but this idea has been justly ridiculed by the more modern nurnismatulogists, who assert that not one coin has ever been exhibited of this metal, which appears to have been employed only in the manufacture of statues, vases, and toys. It is certain, that upon analyzing some of those coins which were said to be of Corinthian brass, no traces of gold could be found.
As gold is not liable to Lte affected by rust, the coins of this metal, in general, are found in a state of excellent preservation. The silver coins have fared worse ; but those of brass worst of all. A single circumstance, however, has frequently proved highly favourable to the coins of brass and copper ; that is, when, by lyint,. in a certain kind of soil, they have acquired a species o°f fine rust, like varnish, which is at once preservative and or namental. This fine rust, says Mr. Pinkerton, which is indeed a natural varnish, not imitable by the art of man, is sometimes of a delicate blue, like that of a turquoise ; t.ornetimes of a bronze brown, equal to that observable in ancient statues of bronze, and so highly prized ; and sometimes or an exquisite green, a little on the azure hue, which last is the most beautiful of all. It is also round or a fine purple, of olive, and ora cream colour, or pale yellow, which last is exquisite, and shows the im pression to as much achantage as paper of a cream co lour, used in all great foreign presses, does copperplates and printing. The Neapolitan //Gana (the rust in ques tion) is of a light green ; and, when free from excres cence or blemish, is very beautiful. Sometimes the pur ple patina gleams through an upper coat of another quality, with as fine effect as a variegated silk or gem. In a few instances, a rust of a deeper green is found ; and it is sometimes spotted l‘ith the red or bronze shade, which gives it quite the appearance of the East Indian stone, called the blood-stone. These rusts are all, when the real product of time, as hard as the metal itself, and preserve it much better than any artificial var nish could have clone ; concealing, at the same time, not the most minute particle of the impression of the coin.