126 ON THE ASSAY MAEKS ON GOLD AND SILVER PLATE. which has relation only to the middle ages. I shall not say anything respecting the antiquity or mode of working the precious metals, that being a distinct subject, but shall endeavour to give a history of the different marks which have been used in this country for stamping gold and silver plate ; and shall treat the subject, as far as I can, in chronological order, by giving — 1st. Some account of the Assa}" as the groundwork of the subject, together with a brief history of the Goldsmiths' Company of London, as being intimately connected with it. 2nd. A short Abstract of the Statutes by wdiich the marks are ordained, and goldsmiths' work regulated. 3rd. A particular account of the several marks them- selves, as used in London, and 4th. Such accounts of the Provincial marks as I have been able to obtain. The precious metals, gold and silver, when in a state of purity, are too soft for the purposes of either coin or plate. It was, therefore, in early times found necessary to employ some other metal to form with them an alloy, to give them the required degree of hardness without materially affecting their colour. Copper or silver are the only metals which can be employed in forming such an alloy with gold. The admixture of silver renders the alloy paler and yellower than pure gold, while copper makes it more red. Copper is the only metal which can advantageously be used for the alloy with silver ; the white metals, tin, lead, and zinc, rendering it brittle, and not easily workable. The maximum hardness is obtained when the copper amounts to one-fifth of the silver, but the colour is scarcely impaired when the alloy consists of equal parts of the tw^o metals ; hence a means of committing great frauds. The proportions, however, found by experience to produce the required results are, for gold, tw^enty-two parts (in technical terms called carats) fine or pure gold, and two parts alloy : and for silver, 11 oz., 2 dw^ts. fine silver, and 18 dwts. of copper in the Troy lb. of 12 oz. This is called the standard, or sterling alloy of the realm, and has been so since the Conquest. It may here be proper to remark that the fineness of gold is estimated by carats ; originally, for this purpose, the Troy ounce w^is divided into 24 carats, and each carat into 4 grains. Now, however, the carat is only understood to be 2^4 th part
