26 Yield A comparison of the carrier and tracer yield measurements are shown in Table 4. These data were selected to show wide ranges of recovery, yet in most cases, the strontium-90 yield (determined by the tracer method) is better than 75%. In those cases where the gravimetric yield is higher than the tracer yield, it is assumed that macro amounts of stable strontium have been leached from the soil. On the basis of many other soil samples analyzed at HASL, it can be said that the strontium recovery is generally better than 80%. The majority of the loss apparently occurs in the oxalate precipitation, for in following separations, only relatively small amounts of strontiumare lost by either coprecipitation or incomplete precipitation. For example, with the tracer, it was possible to determine the percentage of strontium-90 which is coprecipitated with barium as the chromate. Under the conditions of this separation, a very small and consistent amount of strontium is lost at this point. Im the eight cases tabulated in Table 4, the range is 107 to 2.4% coprecipitation. Since the gravimetric yield of strontium is determined by weighing the carbonate precipitate, « study was made of the efficiency of this precipitation. It was shown that under the conditions used in the procedure reported here, the precipitation is quantitative, Ta test the yield under the highest calcium concentration expected, 30 grams of calcium as the nitrate were spiked with stromtian-f2 co.er and 200 milligrams of strontium carrier eaddedo