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{
    "localId": "75723478",
    "label": "Letters Received to H.H. Barker, December 10, 1928",
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    "id": "75723478",
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    "contentType": "document",
    "title": "Letters Received to H.H. Barker, December 10, 1928",
    "citationUrl": "https://catalog.archives.gov/id/75723478",
    "collections": [
        "Safety Light Collection",
        "Records Related to Radium Dial Painters"
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    "seq": 3,
    "pageIndex": 0,
    "type": "document",
    "url": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0001544.pdf",
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    "ocrText": "UNIVERSITY OF MISSOURI\nCOLUMBIA\nDEPARTMENT OF CHEMISTRY\nDecember 10, 1928\nMr. H. H. Barker\nUnited States Radium Corporation\n535 Pearl Street\nNew York, New York\nMy dear Howard:\nYour letter of December 8 has just come to hand and I shall\ntake just a moment to tell you about the difference between your value and my\nvalue in the amount of radium required to liberate the radon which we reported\nfor Dr. Flinn's subject. In explanation of the discrepancy, let me quote the\nparagraph from the letter to Dr. Flinn which will, I think, clear up the matter.\n\"Your letter of the 27th giving experimental data obtained on\nthe girl which you tested for radioactivity has just come to hand. I note that\nthe girl is rather low in activity by the gamma ray method, and your test on Nov-\nember 27 is lower than the one made in June. I have made some approximate cal-\nculations of the radium content of the subject of November 27. The value is ap-\nproximately four micrograms by the gamma ray test. The expired air test seems\nto be perfectly definite also. Assuming a constant for the instrument of 7.3\nX 10⁻⁹ and assuming further that the volume of air contained in the chamber is\n2.7 liters, I find that the expired air from this subject contains about 15. X\n10-12 curies per liter, and if we assume that it takes 15 seconds to blow a liter\nof air through the instrument, then it follows that non emanation continuously\nexpired corresponds to about half a microgram of radium.\"\nPlease note that I have assumed that it takes 15 seconds to\nblow a liter of air through the instrument while you are assuming that the air\nin the chamberwould be expired in 18 seconds. I am assuming that it would be\nexpired in 45 seconds. Your assumption is based upon the relations which we\nhave assumed up to this time but in the expèriments which I have conducted here\nrecently, I have always timed myself and I find that in blowing air through the\nchamber\nsample in series with a drying train that one does not breathe as fast as in\nnormal breathing. I found that it takes about 15 seconds to expire a liter of\nair in the set-up which I make use of. I determined this by finding the time\nrequired to expire six liters of air which I caught in a 6 liter flask filled\nwith water inverted in a pneumatic trough. I found it took a minute and a\nhalf to displace the water and I tried to duplicate the rate of blowing just as\nI did in blowing the expired air through the drying train and the chamber of the\nelectroscope. I therefore feel that your point about using the Douglass bag\nis a very good one and that we should use the Doublass bag in making tests upon\nexpired air. I may add, too, that our Douglass bag outfit has come to hand\nfully equipped with valves and stopcocks.\nUNIVERSITY OF MISSOURI\nCOLUMBIA\nDEPARTMENT OF CHEMISTRY\n- 2 -\nH. H. BARKER\nOne point more--I have now trained myself to breathe more\neasily in making expired air tests and I think that I can have trained myself to\nbreathe almost normally while forcing the air through the chamber, but I believe\nthat most persons when they are asked to blow air into the ionization chamber\ntake deep and long breaths allowing 15 seconds per liter of air for nearer the\ncorrect figure than 18 seconds for three liters.\nWe received notice this afternoon that classwork will end\nat four o'clock today and will not be resumed until January 3. We have more\ncases of \"flu\" than the local hospital can handle.\nMy second series of experiments is nearing completion. I\nhope to render report by the end of the week if all goes well.\nSincerely yours,\nHerman Schlundt\nHerman Schlundt.\nHS\nc\nb"
}