Phosphoric acid is in Colorless, transparent and syrupy liquid or rhombic crystalline;It is odorless and tastes very sour; its melting point is 42.35 centigrade and when heated to 300centigrade it will become into meta phosphoric acid; its relative density is 1.834 g/cm3; it is easily soluble in waterand resolves in ethanol; it may irritate human skin to cause phlogosis and destroy the issue of human body; it shows corrosiveness being heated in ceramic vessels; it has got hydroscopicity.