w Countins Methods The betaezamma activity was determined by countins in a Victoreen unit, the scaler being Model X-327, at the Applied Nisheries Laboratory, University of Washinrton. Counting was started as soon as material could be returned from the test site, processed and ashed. The first counts were made on “ay 22, 1946, while other trays were not counted until September 1, 1948. Some of the counts of activity exceeded the capacity of the scaler. Where such high counts were obtained the amount of material on 2 plate was reduced or the material set aside to decay before countins. Fron decay curves the earlier count could be calculated, The samples were corrected for background, for weicht of samples and for geometry. The background counts averaged 17.0 per minute. Using a U. S. Bureau of Standards Ra D +E standard of approximately *108 disintegrations per second the geometry of the unit was calculated as being 18.0 per cent. No correction was made for scattering, for self-absorption, for absorption by air, and by counter window or for the probability ofionization. Calculation of Counts The activity counts obtained were converted to millimicrocuries per kilocram of sample and recorded in Table I. To convert counts per minute - per gram, to millimicrocurics per kilogram the following formula was used: UNIVERSI1. 2200S JUNIV. OFWASiL Linc wus Mi mpac/kg = net count per mimute (sample wt. )( zeometry) (2.2)