The pure product is the colourless transparent crystal, relative density 2.130. 318.4 degrees Centigrade of points. 1390 degrees Centigrade of boiling point. The city has solid state and two kinds of liquid state to sell the caustic soda: The purely solid caustic soda is white, there are bulk , bar-shaped , granular, the quality is fragile ; The purely liquid caustic soda is the colourless transparent liquid. The solid caustic soda has very strong hygroscopicity. Apt to dissolve it in water, send out heat when dissolving, the aqueous solution is alkaline, there are soft senses ; Dissolve it in the ethanol and glycerin; Do not dissolve it in the acetone , ether . Corrosivity is extremely strong, have function of corroding on fibre , skin , glass , pottery ,etc..