“…Thus his separation system was adopted as the basis for the work reported in this paper. Work on other niobium and tantalum ion exchange sepa-rations has been done (Alimarin and Borzenkova, 1958;Al'tshuler and Subbotina, 1959; Al'tshuler y a/., 1958; Bunney et al, 1959;Cabell and Milner, 1955;Freiling et al, 1959;Freund and Miner, 1953;Fridman and Yudina, 1959;Gilíes etal., 1953;Hague et al, 1954;Huffman et al, 1951;Nikol'skaya/., 1959;Wetlesen, 1960;Wish, 1959;Yajima, 1955).…”