Fluxing.—The word flux means to fuse or to melt, or to put into a liquid state. The office of a flux is to facilitate the fusion of metals. But fluxes do two things. They not only aid the conversion of the metal into a fluid state, but also serve as a means for facilitating the unity of several metals which make up the alloy, and aid in uniting the parts of metals to be joined in the welding of parts
Uniting Metals.—Metals are united in three ways, where heat is used:
First: By heating two or more of them to such a high temperature that they melt and form a compound, or an alloy, as it is called.
Second: By heating up the points to be joined, and then lapping the pieces and hammering the parts. This is called forge work or welding.
Third: By not heating the adjacent parts and using an easily fusible metal, which is heated up and run between the two, by means of a soldering iron.
The foreign material used in the first is called a flux; in the second it is termed a welding compound; and in the third it is known as a soldering acid, or soldering fluid.
The boy is not so much interested in the first process, from the standpoint of actual work, but it is necessary that he should have some understanding of it.
It may be said, as to fluxes, generally, that they are intended to promote the fusion of the liquefying metals, and the elements used are the alkalis, such as borax, tartar, limestone, or fluor spar.
These substances act as reducing or oxidizing agents. The most important are carbonate of soda, potash, and cyanide of potassium. Limestone is used as the flux in iron-smelting