Page:Archaeological Journal, Volume 9.djvu/181

 ON THIS ASSAY MARKS ON GOLD AND SILVKH I'LATE J;i7 of the gold ; and gold of 22 or 18 carats is understood to consist of 22 or 18 parts of line gold, and 2 or G parts alloy. The great frauds ^vhich were abundantly practised by dishonest workmen, and the consequent necessity of affording some protection against them by an examination, under authority, of the ailiclcs put for sale, in order to certify to the purchasers, by an authorised stamp, a certain standard purity of metal, seems to have been the origin of the marks which we find on the gold and silver plate of most countries. In very early times, those who carried on particular trades or handicrafts, were accustomed to form themselves into guilds or fraternities, for the purpose of protecting and regu- lating the trade or mystery, as it was called, which they exercised. These were at subsequent periods incorporated by royal charters, and had particular powers and authority given to them. Amongst such fraternities that of gold- smiths seem to have been early formed in many countries, and it is most probable that one of their objects was to protect their trade against fraudulent workers, and that such an examination as that above mentioned formed part of their duties. The earliest mode of testing the fineness of these metals seems to have been by the touchstone, or " pierre de touche," an imperfect black jasper, or black flinty slate, originally brought from the Mountain of Tmolus in Lydia, and thence also called Lapis Lydius ; it is, however, found in various parts of the world, and indeed any hard black siliceous sub- stance will serve the purpose. This mode of trying the fineness was called "touching." The name obtained for a long time after the adoption of the chemical assay, and the word " touch " seem to have been generally applied to the trial, the standard quality of the metal, and the mark impressed upon it. For the trial of gold two sets of touch needles, or bars, were used, one set alloyed with copper, and the other with silver, twenty-four in each set, according to the twenty-four carats fineness of gold. The streak, or touch made on the touchstone Avith the piece to be examined, was compared with the streaks made by the needles ; these streaks were also washed with aquafortis, which, dissolving the alloying metals, left the gold pure, and thus its fineness was deter-