... crystal, efflorescent in air, easily soluble in water, but insoluble in alcohol, its water solution is slightly alkaline, relative density is 1.63 ... grade1Main content %≥98.098.02P2O5 %≥19.219.43pH of 1% water solution8.8-9.29.0-9.44Chloride, as Cl % ≤0 ... fire-prevention agent for fabric, timber, and paper, also as water softening agent for boiler, food additive, buffering agent, solder, tanning ...