Ask the Scholar

{
    "localId": "75730982",
    "label": "Report, no date",
    "core": "doc",
    "dtoType": "document",
    "citationUrl": "https://catalog.archives.gov/id/75730982"
}

{
    "id": "75730982",
    "sourceUrl": "https://catalog.archives.gov/id/75730982",
    "contentType": "document",
    "title": "Report, no date",
    "citationUrl": "https://catalog.archives.gov/id/75730982",
    "collections": [
        "Safety Light Collection",
        "Records Related to Radium Dial Painters"
    ],
    "iiifBase": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
    "thumbnailUrl": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
    "largeImageUrl": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
    "imageCount": 22,
    "hasImages": true,
    "source": "import",
    "hasTranscription": false
}

{
    "url": "https://catalog.archives.gov/id/75730982",
    "naId": 75730982,
    "levelOfDescription": "fileUnit",
    "recordType": "description",
    "ocrSource": "nara-archive"
}

{
    "seq": 10,
    "pageIndex": 0,
    "type": "photo",
    "url": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_10.jpg",
    "mediaId": "6583689575898f7a",
    "ocrText": "-8-\n10\nTHE EXPIRED AIR METHOD\nAttention has already been called to the extrome sensitiveness of measurements\nin radicactivity depending upon the ionizing effect of alpha particles. While the\nlimit of detecting radium by the gamma-ray method reaches a fow micrograms the\nemanation method of determining radium makes possible the identification of amounts\nof radon of an entirely different order of magnitude. For expressing these quanti-\nmug\nties we may well choose as our unit the micro-microgram, the millionth part of the\nmicrogram, or expressed in grams, the unit is, 10-12 6.\nParadoxical as it may\nseem it is nevertheless true that the tests on expired air as ordinarily conducted\nare probably not any more sensitive than the gamma-ray method when applied to the\ndetection of radium in living persons The explanation for this apparent inconsis-\nteney lies in the fact that the relatively small volume of air, a liter or two, the\nionization chambers of alpha ray electroscopes hold, contains at best only that\nsmall fraction of the radon which is generated by the radium present in the subject\nduring the time it takes for a few breaths. Per second this amount will be only\n2.1 x 10-6 or roughly, 0.000005 of the equilibrium quantity. It is the equili-\nbrium quantity which comes into consideration in S tating the sensitiveness of the\nemanation method of testing for radium. While this matter will be explained and\nillustrated more fully in the theoretical part of thi S report, let us call attention\nto another factor which materially influences the sensitiveness of the expired air\nmethod: Since the free emanating power of radium in the solid state is naturally\nthomanation\nrelatively small, it follows that only a smäll fraction of that continuously pro-\nduced by the radium present will find its way into the blood stream and lungs.\nIf for a moment we generously assume that all of the radon continuously produced\nis exhaled, then none of its transformation products will accumulate in the body,\nwhich means that no gamma radiation will be manifest for it is emitted entirely\nfrom radium C. which follows radon in the transformation series. Indeed we may go\na step farther. The quantity of radium detected by the gamma-ray mothod of"
}