BORON

The base of boracic acid, discovered by Davy in 1807. It may be procured by heating dry boracic acid with pota ium. Itis a dark olive-coloured substance, a nonconductor of electricity, insoluble in water, infusible, and of a specific gravity = 2. Heated to redne it burns into boracic acid, which consists of 20 boron -^ 48 oxygen. Boracic acid is found in.the hot springs, and amongst the volcanic products of the Lipari islands, and in the waters of Sa o in the Florentine territory; it also occurs in some minerals. It may be obtained by adding exce of sulphuric acid to a strong solution of borax. Its specific gravity is 1"48. In its usual state of scaly crystals it is a hydrate, composed of 68 dry acid -f 27 water. In this state it requires about 30 parts of cold and 3 of boiling water for its solution. It di olves in alcohol, and the solution burns with a characteristic green flame. It reddens litmus; but renders turmeric brown, like an alkali. When its water is driven off by fusing it at a high heat, the anhydrous acid concretes into a gla y substance of the specific gravity of 1-8. It is a useful flux, and was formerly used in medicine under the name of Homberg's sedative salt. [s. 168]