Pure caustic soda is Colorless, tran***rent crystals, melting point :318.4℃,boiling point:1390℃, crispy. Pure solid caustic soda appear white, block ,flake, bead , easily soluble in water ,can release lots of heat.in water appear alkaline, feeling creamy. soluble in ethanol and glycerol, not soluble in acetone ,ether. strong corrosive, corrupt fiber ,skin, glass ,ceramic ,etc.