Elution procedure . The sample was allowed to pass through the column at a rate of 0.2 - 0 5 ml per minute and then the column was washed with 50 ml of O.2N HCl. The HCl fractions, ions not adsorbed to the resin, fractions. which contained are designated as the anion The cations adsorbed to the resin were removed progressively by passing through the column 50 ml of 0.5 per cent oxalic acid followed by 5 per cent citric acid solutions adjusted to pH 3.5, 4.1, 4.6, 5.1, 5.6 and 6,1 with NH,OH. The eluates were collected in ‘test tubes and dried for gamma counting. Aliquots were removed for beta counting. The resin bed was removed from the column at the termination of the elution procedure and was ignited. The ash was counted for beta and gamma activity The disintegration rates for the individual isotopes were determined from the beta and gamma counts. Gamma survey procedure After the isotope wr85 was identified in the plankton samples, gamma spectra were made from different types of samples collected in and around the Eniwetok Test Site during the in- terval April 28 to September 17, 1958. The radiotungsten was identified by the 0.055 MEV gamma peak and the disintegration rates of this isotope as well as those of the other gamma