Boric Acid

Boric Acid BP Ph Eur H3BO3 -- 61.8 -- CAS 10043-35-3 Boric Acid BP DEFINITION Boric acid contains not less than 99.0 per cent and not more than the equivalent of 100.5 percent of H3BO3. CHARACTERS A white, crystalline powder, colourless, shiny plates greasy to the touch, or white  crystals, soluble in water and in alcohol, freely soluble in boiling water and in glycerol  (85 per cent). IDENTIFICATIONA. Dissolve 0.1 g by gently heating in 5 ml of methanol, add 0.1 ml of sulphuric acid and ignite the solution. The flame has a green border. B. Solution S (see Tests) is acid. TESTS Solution S Dissolve 3.3 g in 80 ml of boiling distilled water, cool and dilute to 100 ml with  carbon dioxide-free water prepared from distilled water. Appearance of solutionSolution S is clear and colourless. pHThe pH of solution S is 3.8 to 4.8. Solubility in alcohol Dissolve 1.0 g in 10 ml of boiling alcohol. The solution is not more opalescent than reference suspension and is colourless. Organic matter It does not darken on progressive heating to dull redness. Sulphates 10 ml of solution S diluted to 15 ml with distilled water complies with the limit test  for sulphates (450 ppm). Heavy metals