in fencing, denotes a blunt sword, or one that has a button at the end covered with leather, used in learning the art of fencing.

**Foil**, among glass-grinders, a sheet of tin, with quicksilver, or the like, laid on the back side of a looking-glass, to make it reflect. See Foliating.

**Foil**, among jewellers, a thin leaf of metal placed under under a precious stone, in order to make it look transparent, and give it an agreeable different colour, either deep or pale; thus, if you want a stone to be of a pale colour, put a foil of that colour under it; or if you would have it deep, lay a dark one under it.

These foils are made either of copper, gold, or gold and silver together. The copper foils are commonly known by the name of Nuremberg or German foils; and are prepared as follows: Procure the thinnest copper-plates you can get; beat these places gently upon a well-polished anvil, with a polished hammer, as thin as possible; and placing them between two iron-plates as thin as writing paper, heat them in the fire; then boil the foil in a pipkin, with equal quantities of tartar and salt, constantly stirring them till by boiling they become white; after which, taking them out and drying them, give them another hammering, till they are made fit for your purpose; however, care must be taken not to give the foils too much heat, for fear of melting; nor must they be too long boiled, for fear of attracting too much salt.

The manner of polishing these foils is as follows: Take a plate of the best copper, one foot long and about five or six inches wide, polished to the greatest perfection; bend this to a long convex, fasten it upon a half roll, and fix it to a bench or table; then take some chalk, washed as clean as possible, and filtered through a fine linen cloth, till it be as fine as you can make it; and having laid some thereof on the roll, and wetted the copper all over, lay your foils on it, and with a polishing stone and the chalk polish your foils till they are as bright as a looking-glass; after which they must be dried, and laid up secure from dust.