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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
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"ocrText": "UNIVERSITY OF MISSOURI\nAPR 17 1929\nCOLUMBIA\nDEPARTMENT OF CHEMISTRY\nApril 15, 1929\nMr. H. H. Barker\nUnited States Radium Corporation\n535 Pearl Street\nNew York, N. Y.\nMy dear Howard:\nThis past week has given me a surprise. Have been at work making radium\ndeterminations on residues of excreta-faeces-Mis: Grace Freyer. Four samples have\nbeen assayed. No trace of radium found.\nBy measuring activity of these samples, film method, before they were\ndissolved the drift was found to be from two to three times the natural drift, the in-\ncrease being about the same as the residue samples of Mrs. Dunschott, which Dr. Flinn\nturned over to me last Fall, and whose radium content was determined by the same\nmethod\nemployed with the Freyer samples.\nThe method followed consisted in (1) Solution in (1:1) HN03, and boiling,\nno\nbarium\nsalt added. (2) Flasks stoppered and solution stored in sealed flask for two\nweeks.\n(3) Emanation separated by boiling; gas collected and transferred to standar-\ndized\nelectroscope (A slight carbonaceous residue remained when sample was first boiled\nwith\nHNO3) . In first two samples not dilute NaOH was used in gas collecting burette.\nIn next two no NaOH was added. (4) Insoluble residue was filtered off. (5) Clear\nsolutions evaporated to dryness, and ignited very gently. (5) Dry recovered residue\nagain tested for activity by film method.\nA blank was first run.\nNat. drift before 0.0124\ndiv/sec\nNat. drift after gas in 0.0125 div/sec\nF.9 Obs. drift 0.0124 div/sec\nObs. drift 0.0114 div/dec after 3 hours\nF.13 Nat. drift 0.0118\ndiv/sec\nObs. drift gas in 0.119 div/sec\nF.12 Nat. drift 0.0119 div/sec\nObs. drift 0.0119 div/sec\nF.2 Nat. drift 0.0119\ndiv/sec\nObs. drift 0.0119 div/sec"
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