14 and La66 and calculated each radionuclide'’s atom ratio to 9574 at zero time. The ratios of 89sr Sly | 136¢5 and 141¢¢@ to %zr were plotted against the 14083 to zr ratio (Fig. 5). In this work I have made the following assumptions: @ Volatile elements do not fractionate from each other. e Refractory elements do not fractionate from each other. e The composition of offsite fallout can be represented by the volatile phase and a fraction of the refractory phase. It follows directly from these assumptions that the atom ratio of a volatile mass chain to a refractory mass chain (e.g., 9574) is a linear function of any other such volatile mass chain atom ratio to the same refractory mass chain. The line that plots this function must pass through the point representing unfractionated debris. The data show this linear behavior and the 91y | 136¢¢, 140g, and 141,144 0, agree, within experimental error, with the values calculated for unfractionated debris (solid circles in Fig. 5). However, the BOC, data are low by a factor of about five. no conclusions have been drawn from these data. Therefore, Ruthenium data have been omitted because they appear to be low, probably because of the intractable chemical behavior of that element. It should be noted that Freiling (Fr6l1, Fr63) has shown that such ratios in fractionated debris are power functions, not linear functions of each other. His ratios range over an order of magnitude above and below the unfractionated value. The Nevada tower shot data, on the other hand, are close to the unfractionated values, and constitute a special case in which the simplifying assumptions lead to a linear relation.