Most indelible inks contain nitrate of silver, the stain of which may
be removed by first soaking in a solution of common salt, and
afterward washing with ammonia. Or use solution of ten grains of
cyanide of potassium and five grains of iodine to one ounce of water,
or a solution of eight parts each bichloride of mercury and chloride
of ammonium in one hundred and twenty-five parts of water.