The method of Pollard et al. [J. Chem. Soc. 1863 (1951)] possesses the disadvantages that (a) tailing takes place in the case of vanadium and molybdenum, and (b) tungsten remains at the on Anal spot, which tends to retain some moly-bdenum. It is egpecied to solve these troubles by keeping the valency and the state of association unchanged during elution, and confining the elements tested in the form of stable and soluble complexes. The per-acids formed by these three elements and hydrogen peroxide [Feigl and Raacke, Anal. Chim. Acfat 1,317(1947)] were tried and found to be satisfactory.