or Allay, properly signifies a proportion of a baser metal mixed with a finer one. The alloy of gold is estimated by carats, that of silver by penny-weights. See Gold, &c. In different nations, different proportions of alloy are used; whence their moneys are said to be of different degrees of fineness or baseness, and are valued accordingly in foreign exchanges.

In a more general sense, the word is employed in chemistry to signify the union of different metallic matters.—As an infinity of different combinations may be made according to the nature, the number, and the proportions of the metallic matters capable of being alloyed, we shall not here enter into the detail of the particular alloys, all which are not yet nearly known. Those which are used, as Bronze, Tombac, Brass, White Copper, &c. may be found under their particular names; and what is known concerning other alloys may be found under the names of the different metals and semi-metals.