among mechanics, the joining and fastening together two pieces of the same metal, or of two different metals, by the fusion and application of some metallic composition on the extremities of the metals to be joined. See the last article.

To folder upon silver, brass, or iron: take silver, five penny-weight; brass, four penny-weight; melt them together for soft folder, which runs soonest. Take silver, five penny-weight; copper, three penny-weight; melt them together for hard folder. Beat the folder thin, and lay it on the place to be soldered, which must be first fitted and bound together with wire, as occasion requires; then take borax in powder, and temper it like pap, and lay it upon the folder, letting it dry; then cover it with quick coals, and blow, and it will run immediately; take it presently out of the fire, and it is done. It is to be observed, that if any thing is to be soldered in two places, which cannot well be done at one time, you must first folder with the harder folder, and then with the soft; for if it be first done with the soft, it will unfold again before the other is soldered. Let it be observed, that if you would have the folder run about the piece that is to be soldered, you must rub such places over with chalk.

In the soldering either of gold, silver, copper, and all the metals before-mentioned, there is generally used borax in powder, and sometimes rosin. As to iron, it is sufficient that it be heated red hot, and the two extremities thus hammered together, by which means they will become incorporated into one another.