... colorless crystal,efflorescent in air,easily soluble in water,but insoluble in alcohol,water solution is slightly alkaline,relative density is 1.63 ... fire-prevention agent for fabric,timber,and paper,also as water softening agent for boiler,food additive,buffering agent,solder,tanning ... , % min98.098.0Phosphorus pent-oxide, % min19.419.4PH of 1% water solution .8.8-9.29.0-9.4Water insoluble, % max0.10 ...