Di-Ammonium Phosphate (DAP) appears as a white or colourless crystal with a relative density of 1.619 g/cm³ and a melting point of 155.0 ℃. It is 100% soluble in water, insoluble in alcohol and the pH of a 1% solution is 8.0; in air it gradually loses ammonia and converts into mono-ammonium phosphate. It is mainly used in the manufacture of fire-extinguisher powder and flame retardants, as a fire-proofing agent for fire-resistant doors, fabric and paper, and is one of the ingredients for liquid and high-quality water-soluble fertilizers.