16 (Ed59) f,9¢ only when the mass chain A is 100% volatile, e.g., 136¢5, Equations for specific nuclides are in Appendix 3. The values of r(91), r(136), r(140), and r(141) generally agree, within experimental error, in the 25 samples measured. These values are averaged for each sample; the averages appear in Table 3. The values of r(A) are plotted against radial distance from ground zero (Fig. 6) and arrival time (Fig. 7). and distance from ground zero. Clearly, r(A) increases with time The value of r(A) = 2 (half refractories present) can be used to characterize the nuclide composition of the offsite fallout within 160 miles from ground zero. The relative amount of volatile phase increases with distance, indicating that the volatile phase is relatively enriched on the smaller particles, even though there was a constderable amount of unmelted dust entrained in the cloud. This correlation is consistent with the concept that the refractory nuclides are contained in the bulk of the particles formed by condensation and the volatile nuclides are deposited on the surface. As time and distance from ground zero increase, the size of the fallout particles decreases. Values of r(A) for each size fraction were averaged for each shot. The average values are shown in Table 4 and in Fig. 8.