It is doubtful whether any treatment would prevent corks used as stoppers for bottles or flasks being acted upon by chemicals. It is usual to treat corks with melced paraffin wax, the corks being kept in the melted material for several hours. Cerasin wax is a better material, and has a higher melting-point. For this purpose, steep the corks for several hours in silicate of soda solution (1 part of silicate to 4 parts of water), and then in lime water for several hours. They can be waxed afterwards, if desired.