ee SECRET , UNCUASSIFIED APPENDIX C BM-1175-AEC $2-30-53 | 22 - THE ANALYTICAL METHOD A. Preliminary treatment of samples Before any chemical preperation was done, most of the solid gamples were dried or burned in an oven or incinerator and then reduced to ashjin a mffle furnance at 900°C. Samples treated in this way included the humaf, alfalfa, \ cheese and milk specimens. The Bureau of Plant Industry at Beltsville, Maryland, processed the soil samples and sent them to us in the form of caldium oxalate. The water samples, including the rain, snov, lake, river andJocean samples, were filtered to remove solid material. B. Chemical preparation of samples The ashed samples were dissolved in concentrated HCl and condentrated HNO, was also added if the sample did not go into solution satisfactorily. The residue, if any, was then filtered off, and, with the exceptidn of the human group, strontium carrier was added to the solution, which was then milked with yttriun. The alfalfa samples were still highly contaminated after the [first milking. Repeated ferric phosphate precipitations were made to r@move the rare earth contaminants. The strontium carrier which had been added wds isolated using Harley's method, and then purified. The soil samples in the form of calcium oxalate were dried, oxides, dissolved in concentrated HCl, diluted with water, and ited to ed. The milking technique adopted by the Chicago group for the determinatfon of the sr” content of various types of sample essentially consists of obtaingng an HCl solution of the sample, adding carrier for the yttrium, separat the yr daughter of any sr” present in the sample by a phosphate precipifsation of the 1045323 UBCLASSIFIED LANL