——— MR. EISENBUD: That ie very good. Our conclusion about these pepers hasn‘t changed because our level of confidence has. We concluded about two years ago that we were about 70 per cent efficient, Well, that was on the basis of rather flimsy tests but on the basis of the studies that Brandt has now completed, I have a pretty high degree of confidence in this, at least compared to a pot. Of course we can't possibly say that the pot is the absolute method either, ¥hat we want is comparison of the two things we were interested in; one is the estimate of etrontium as made by our gummed paper method and the other is the measure of strontium as found in the eoil, This is really the test, There is more than Just the ine efficiency of the paper to coneider here because as Harley points out, there is an inherent fractionation of strontium 90 with distance as well as the fact that there may be selected physical separation of the strontium 90 off of the parers. a 210

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