U.S.SoilPropran The advantages and disadvantages of gummed film for fallout measurement have been discussed many times previously. One possible calibration is the comparison of cumulative gummed film results with analyses of soils taken at identical locations. The first such collec- tion was undertaken at 17 Weather Bureau stations in October 1955 and was repeated in Cctober 1956. In both cases, 0-2 inch and 2-6 inch depths were taken, and Sr-90 leached with 6N HCl. The O-2" depths for the 1955 samples were reported in NYO-1,751. (2) The 2-6" depths ,eve the analysts considerable difficulty due to interference from thorium chain isotopes and they were not reported. A pro- cedure has been worked out for these soils and those having residual sample available will be reanalyzed. The date for the 1956 samples is shown in Table 1 and a plot of soil activity against the values estimated from the gummed film is shown in Fig. 3. 4s in the 1955 data, Albuquerque, Grand Junction, and Salt Lake City <':>. lower soil values than predicted. The mean ratio of soil/film is 2.°2 for the 1) "normal" samples. (Gummed film values already multiplied by 1.6 correction factor.) If the 1955 samples are corrected to total me /mi* using the 1956 ratio for total tc top-soil activity, the mean ratio becomes 2.4. of 1.6 reported in NY¥O-L.751 was for the 0-2" depths only. The value