borax(redirected from borak)
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sodium tetraborate, Na2B4O7·IOH2O, crystal hydrate of the sodium salt of tetraboric acid. It is found in nature in the form of the mineral borax (or tincal), which is white or, less frequently, gray and yellow in color; its density is 1, 690-1, 720 kg/m3. Borax is soluble in water (1.6 g of the anhydrous salt in 100 g of H2O at 10° C). Aqueous solutions of borax are alkaline and absorb CO2 from the air. Borax is decomposed by strong acids. It is used in soldering, since fused borax dissolves oxides of metals and in that way cleans the metallic surfaces to be soldered. Borax is used in the production of special kinds of glass (mainly optical), enamels, glazes, for tanning leather, for making substances borated, and in agriculture as a trace-element fertilizer.
Borax is a medicinal preparation that has antiseptic action. It is used in the form of a 3-5 percent solution for irrigation and lubrication of the buccal cavity, nose, and nasopharynx in various infectious diseases (tracheitis, head cold, stomatitis, and others). Borax is prescribed internally for treatment of epilepsy (especially in children).