INTRODUCT FON The Chicago Sunshine Project will terminate its activities during ‘.ugust 1956. This bulletin will be the last report of results obtained bv the Chicapo Laboratory. ill reselts of sr70 analyses of biological materials, soils, waters and air filters accomplished by the Chicago Sunshine Project, including results for samrles assayed by the Nuclear Science and Engineering Corporation, PittsLurgh, Pennsylvania, under subcontract, are reported in the University of Chicago Bulletins No. 11 and No. 12, results to December 1, 1955, presented in this report. Bulletin No. 11 includes cumlative Results obtained since December 1, 1955 are .. limited number of analyses of human bone, milk, foreirn soil and intarctic snow core samples, now in progress, will be sub- mitted to the Division of Biology and Medicine, U. 5. .itomic Energy Commission in a brief letter renort during -.usust 1956, A detailed discussion of experimental methods, including preliminary processing of samples, chemical procedures and the counting method, has been reported, 1, The report is being further distributed as U, 5, itomic Energy E, «, Martell, The Chicago Sunshine Method; Absolute :.ssay of Sr?0 in Biological Materials, Soils, “iaters and air Filters, Enrico Fermi Institute for Nuclear Studies, University of Chicago, May 1956. Commission publication, sECU-3262, Additional copies will be available from the Office of Technical Services, Department of Commerce, “Jashington 25, D, C. The results have been discussed to a considerable extent by 7, F, Libby .¢»3 2. ‘I, F, Libby, "Radioactive Strontium and Radioactive Fallout," Science 3. “I, F, Libby, "Radioactive Strontium Fallout," Proc, Nat. Acad. Sci. h2, 223, 657 (1956). ~ NYOO 365 (1956). S2