the name of a saline substance brought from the E. Indies in large masses, composed partly of large crystals, but chiefly of smaller ones, partly white and partly green, joined together, as it were, by a greasy yellow substance, intermingled with sand, small stones, and other impurities. The purer crystals, exposed to the fire, melt into a kind of glass, which is nevertheless soluble in water.

This salt, dissolved and crystalized, forms small transparent masses. The origin of this salt is not known; but experiments have clearly shown, that it consists of a fixed alkaline salt, the same with the basis of sea-salt, in some degree neutralised by another saline substance, which is supposed to exist nowhere but in borax itself.

The medical virtues of borax are little known: In doses of half a dram to two scruples, it is supposed to be diuretic, emmenagogue, and a promoter of delivery.