Essay, or Say, in Metallurgy, the proof or trial of the goodness, purity, value, &c. of metals and metallic substances. See Essay.

In ancient statutes this is called touch; and those who had the care of it keepers of the touch.—Under Henry VI. divers cities were appointed to have touch for wrought silver-plate, 2 Hen. VI. c. 14.—By this, one might imagine they had no better method of assaying than the simple one by the touchstone; but the case is far otherwise. In the time of King Henry II. the bishop of Salisbury, then treasurer, considering that though the money paid into the king's exchequer for his crown-rents did not answer numero et pondera, it might nevertheless be mixed with copper or brass: wherefore a constitution was made, called the trial by combustion; which differs little or nothing from the present method of assaying silver. See a description of it in the Black Book in the Exchequer, written by Gervase of Tilbury, c. xxi. This trial is also there called essaim, and the officer who made it is named fuser. The method still in use of assaying gold and silver was first established by an act of the English parliament 1354.