BORAX, or BITIO'RATE OF SODA, is-found native as a saline incrustation on the shores of certain lakes in Persia and Thibet. It also occurs in India, China, Ceylon, Saxony, and South America. When collected on the banks of the lakes, it is impure, and goes by the name of tincal. The latter is purified by acting upon it with a solution of caustic soda, which removes the fatty matter that the crystals are coated with, to prevent evap oration of the water they contain, and thereafter dissolving in hot water and lag. B. is likewise prepared from boracic acid (B0,), (q.v.), by solution in Lolling water, and the addition of a boiling solution of ordinary carbonate of soda when B. (Na0,2130t) is formed, and carbonic acid (CO,)is disengaged, and on cooling in wooden tanks lined with lead, the crystals of B. separate. The common crystalline variety of B. contains 10 equivalents of water 10110); hut if a stronger than. ordinary solution be allowed to cool, crystals begin to separate at a higher tempera ture than usual. which contain only 5 atoms of water 5110). B. is solu
ble in water to the extent of one part of the salt in two parts of hot water, and in twelve of cold, yielding a clear solution with a sweetish taste. It is readily reduced to powder, and is then known as powdered borax. It is of great use in the chemical arts. As an assistant agent M experimenting with the blow-pipe (q.v.), B. is of great service, from the readiness with which it forms colored glasses with the various metallic oxides. It is also employed in the manufacture of enamel, and for glazing or coating vessels in English as also in the formation. f the paste for artificial gems. s. To the metal lurgist, it is an aid in the readiness with which it promotes the fusion of metallic mix tures, and the separation of the metals; and to the solderer of all metals it is of service in forming a thin glassy coating over the edges of the metals, which prevents their oxi dation at the time they are being joined together. B. is also used in dyeing.