“…Many of these ion exchangers, although formed in large particles or beads in order to facilitate rapid filtration, appear to be porous to the reactive ions and do not disintegrate upon repeated reaction and regeneration (17,58). Particular properties of many of these products have been reviewed by Myers (92) and by Applezweig (7). Surface-active substances such as charcoal or alumina may be converted into ion-exchange adsorbents by preliminary adsorption of acids or bases (70, 138) just as cloth is rendered more attractive to dyes by treatment with mordants.…”