Letters Received to H.H. Barker, April 15, 1929

UNIVERSITY OF MISSOURI APR 17 1929 COLUMBIA DEPARTMENT OF CHEMISTRY April 15, 1929 Mr. H. H. Barker United States Radium Corporation 535 Pearl Street New York, N. Y. My dear Howard: This past week has given me a surprise. Have been at work making radium determinations on residues of excreta-faeces-Mis: Grace Freyer. Four samples have been assayed. No trace of radium found. By measuring activity of these samples, film method, before they were dissolved the drift was found to be from two to three times the natural drift, the in- crease being about the same as the residue samples of Mrs. Dunschott, which Dr. Flinn turned over to me last Fall, and whose radium content was determined by the same method employed with the Freyer samples. The method followed consisted in (1) Solution in (1:1) HN03, and boiling, no barium salt added. (2) Flasks stoppered and solution stored in sealed flask for two weeks. (3) Emanation separated by boiling; gas collected and transferred to standar- dized electroscope (A slight carbonaceous residue remained when sample was first boiled with HNO3) . In first two samples not dilute NaOH was used in gas collecting burette. In next two no NaOH was added. (4) Insoluble residue was filtered off. (5) Clear solutions evaporated to dryness, and ignited very gently. (5) Dry recovered residue again tested for activity by film method. A blank was first run. Nat. drift before 0.0124 div/sec Nat. drift after gas in 0.0125 div/sec F.9 Obs. drift 0.0124 div/sec Obs. drift 0.0114 div/dec after 3 hours F.13 Nat. drift 0.0118 div/sec Obs. drift gas in 0.119 div/sec F.12 Nat. drift 0.0119 div/sec Obs. drift 0.0119 div/sec F.2 Nat. drift 0.0119 div/sec Obs. drift 0.0119 div/sec