CHAP. V.
PRECIOUS METALS.
147
less loss by friction on the gold coin at that thanat subsequent periods, on account of the greatpurity of the metal.
It is well known now, and seems to have beenascertained at an early period, that the purerthe gold is, the less consumption of it from fric-tion arises in use. Without examining the che-mical reasons for this, the fact is undoubted, andthe ancients seem to have been acquainted withit. They had early acquired the art of refiningit. We learn from Pliny 1 , that in his time goldwas refined by mercury, which mingled with it,but rejected all alloy; and the gold was after-wards freed from the mercury by squeezing bothin skins; in which operation the mercury ranthrough, and left the gold in a pure state.
In the time of Philip of Macedon , the art ofrefining had arrived at great perfection, for hiscoins are found of the utmost purity; and theyare rivalled by those of his son Alexander, andof the other princes and cities which immedi-ately followed. The purest gold coin now cir-culating in Europe is that which issues from theEnglish mint. Our standard gold consists oftwenty-two carats of pure gold, and two carats ofalloy. That of all the other kingdoms of Europe contains more alloy in different proportions-;but except the Dutch ducats, which are few in
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