a7. However, if Fe>> were present in this sample in the same ratio the same to pe? as that observed in other samples collected at tine, the activity would have been approximately 1,300,000 d/m of Fe>. Te ammonium citrate fraction at pH 3.5 exhibited high levels of BP the 7 Because radiation in samples 3.5 b-c-d-e (Fig. 1). spectrum contained several peaks which could not be iden- tified a further ion exchange separation was made (Fig. 1, inset) on this fraction according to the method of Kimura etal. (1956). The first peak of the second elution with ammonium citrate at pH 3.1 was sharply separated from the next peak at pH 3.3 (Fig. 1, inset). Although the first peak had a high P tegration rate the Y activity was very low. disin- The isotope in this peak was identified as y7t Since yttrium was known to be eluted at this position and in addition the A radiation had a maximum energy equal to that of y?l (1.54 MEV, 600 mg/em® range in aluminum). The observed half life for this fraction was iden- tical with the 58-day half life of y7+. ne total v2) content of the sample, based on the g count, was 46,400 d/m, The second peak of the second elution occurred at pH 3.3, fractions ¢ through r(Pig. 1, inset). tions comprising this peak by Y Examination of the frac- spectrometry revealed Y of the following energies (Fig. 3). 0.08 MEV (weak) 0.12 MEV W oa Lome + 7 yb. v . 4 1% ¥ we peaks