\Bo"rax\, n. [OE. boras, fr. F. borax, earlier spelt
borras; cf. LL. borax, Sp. borraj; all fr. Ar. b?rag, fr.
Pers. b?rah.]
A white or gray crystalline salt, with a slight alkaline
taste, used as a flux, in soldering metals, making enamels,
fixing colors on porcelain, and as a soap. It occurs native
in certain mineral springs, and is made from the boric acid
of hot springs in Tuscany. It was originally obtained from a
lake in Thibet, and was sent to Europe under the name of
tincal. Borax is a pyroborate or tetraborate of sodium,
Na2B4O7.10H2O.
{Borax bead}. (Chem.) See {Bead}, n., 3.