Bō'rax, n.

n. [Fr. borax, Sp. borrax, It. borrace, Ar. bāraq, niter, saltpeter, from bāraqa, to shine.] (Chem.) Biborate of soda; a salt formed by a combination of boracic acid with soda. It was originally obtained from a lake in Thibet, and was sent to Europe under the name of tincal. It is of a white color, or sometimes grayish, or with a shade of blue and green. It is an excellent flux in many metallurgical operations, and useful in soldering. Dana.