-10The disintegration rates of Mn? and zn? were determined entirely by than one 7 7Y counting. Also, in those instances where more -emitting isotope was present in a fraction, the disintegration rate for each isotope was calculated from the 7 spectrum, back-calculated to c/m with the observed fA -count rate. calculated and observed £8 BP , totaled, and compared The difference between the count was rarely greater than 10 per cent and was usually 5 per cent or less. The radiochemical separations for the fission products and for Fe? and Fe? were made according to the methods outlined by Kleinberg (1954) of the Los Alamos Selentific Laboratory. The methods for Mn, zn, and vanadium were taken from the procedures developed at the University of California Radiation Laboratory (Meinke, 1949). The determinations for cobalt were made according to two different methods: one was taken from Kleinberg and the other from Hillebrand and Lundell (1953).