... 40.0Boric anhydride B2O3 , %45.0-48.0Loss on ignition %13.5-15.5Fineness (325 Residue on sieve ),% ≤0.1Specific gravity ... , g/cm32.67Melting point, oC980Losing temperature of crystal water, oC >320Refractive ... .5Fineness (325 Residue on sieve ),% ≤0.1Specific gravity , g/cm32.67Melting point , oC980Losing temperature of crystal water , oC > ...