The adsorptive properties of perlite, an expanded volcanic glass, have been studied. Several activating treatments were investigated, air oxidation it 400 degrees Centigrade appears to be the best, The adsorption of the basic dye emethylene blue yields a saturation valve of 50 milligrams per gram of perlite.  The acid dye cotton blue showed no measurable adsorption. A maximum adsorption of 15 millimoles of acetic acid and one milligram of iodine were found in aqueous solution. A high value of 1.33 milligrams of iodine per gram of perlite were found in methyl alcohol solutions. The surface area of perlite appears to be rather low, The material does not seem suitable for use as avcommercial adsorbant.