Forms: 4–7 boras, 5–6 borace, 6 borras, 7 baurac(h, boraxe, 6– borax; pl. (Obs. rare) boraces. [ME. bora·s, a. OF. boras (borras, bourras), ad. med.L. baurach, borac, boracum, and borax, borac-em, a. Arab. [Arabic] variously pronounced bauraq, būraq, bōraq, prop. ‘natron,’ but also ‘borax’: referred by the lexicons to the Arab. baraqa to glisten, but prob. ad. Pers. būrah borax. According to Léman introduced into the Romanic langs. about the 9th c. Cf. Sp. borrax (now written borraj), mod.F. borax, It. borrace.]
1. A native salt; the acid borate of sodium, or biborate of soda (Na2 B4 O7): having, when pure, the form of a transparent or whitish crystal, or white powder, but also imported as crude borax or tincal, a greenish mass greasy to the touch.
c. 1386. Chaucer, Prol., 630. Ther nas quyksilver, litarge, ne brimstone, Boras, ceruce, ne oille of tartre noon.
1483. Cath. Angl., 37. Borace, Borax.
1543. Traheron, Vigo’s Chirurg. (1586), 433. Boras, others write it Borax, and Plinie saith, that it is a liquor in pits.
1623. Cockeram, Boras, a white substance like salt-peeter wherewith goldsmiths solder gold and siluer.
1678. R. R[ussell], Geber, I. iii. 9. Glass and boraces.
1684. Phil. Trans., XIV. 610. The other species [of Nitre] they term Baurac, which they used in seasoning their meat.
1810. Henry, Elem. Chem. (1826), I. 566. Tincal, which, when purified, becomes the refined borax of the shops.
1876. Harley, Mat. Med., 157. Borax is supposed to have been the Chrysocolla of Pliny.
2. Borax beads, beads made of borax, used in blowpipe analysis to distinguish the metallic oxides, and test minerals by the characteristic colors which they give in the oxidizing and the reducing flame.
