CHAP. XXIII.

WEAR OF COIN.

175

perfect knowledge of assaying that then existedthe small quantity of those inferior metals couldnot easily be detected.

It has been shown by the experiments of Mes-sieurs Cavendish and Hatchett that if our English standard gold, consisting of two parts of alloy intwenty-four, were to have that alloy formed of amixture of iron and tin, the loss by friction wouldbe five times as much as it is with the kind of alloyapplied at the mint 1 ; if the alloy were copper andtin it would be nearly four times as much. Thereis no reason to conclude that the ancients everused any alloy except tin, iron, and copper, andwe may conclude therefore that the loss on theirffold coins was from four to five times as great aswould be experienced on the modern English goldcoins.

The maximum of durability for gold coinsseems to be fixed at twenty-two parts in twenty-four of pure gold with the appropriate alloys.When the fineness ascends or descends from thatpoint, the consumption by abrasion is increased.Thus the experiment of Mr. Cavendish and Mr.Hatchett shows, as before stated, that gold of thefinest quality that can be worked, viz. of twenty-three carats and three quarters fine, suffers a lossof four times that of the standard of twenty-twofine. On the other hand, the coins below that

1 See note, page 170.