Lactic acid pure product as a colorless liquid, industrial products is a colorless to pale yellow liquid. Odorless, hygroscopic. The relative density of 1.2060 (25/4 ° C). Melting point of 18 ℃. The boiling point of 122 ° C (CVP). The refractive index nD (20 ° C) 1.4392. Miscible with water, ethanol, glycerin, insoluble in chloroform, carbon disulfide and petroleum ether. Thermal decomposition at atmospheric pressure, concentrated to 50%, some into milk anhydride, the products often contain 10% -15% of the milk anhydride