“…Fritz and Abbink (71) used cation exchange in acetone-water-HC1 solutions to concentrate traces of nickel and copper in salts of Cd, Zn, and Fe(III) which were absorbed only weakly in this medium. Two papers (88,121) describe determination of impurities in gallium arsenide, removing the major constituents by ion exchange and solvent extraction. A new technique for separating trace impurities from certain chloride salts is precipitation ion exchange (289).…”