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{
    "localId": "75723314",
    "label": "Letters Received to H.H. Barker, November 6, 1928",
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    "id": "75723314",
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    "contentType": "document",
    "title": "Letters Received to H.H. Barker, November 6, 1928",
    "citationUrl": "https://catalog.archives.gov/id/75723314",
    "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_0001497.pdf",
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    "ocrText": "UNIVERSITY OF MISSOURI\nCOLUMBIA\nDEPARTMENT OF CHEMISTRY\nNovember 6, 1928\nNOV 1928\nMr. H. H. Barker\nUnited States Radium Corporation\n535 Pearl Street\nNew York City\nMy dear Barker:\nLast evening I wired you stating that it will\nbe possible to attend the examination of the girls during the week\nof November 19. I shall, however, not be able to leave Columbia\nuntil late Friday evening or Saturday morning, and I shall there-\nfore have to miss the football game, much to my regret. As soon\nas I know more definitely about train service I shall let you know.\nI hope, however, to have a good visit with the Underwoods.\nTomorrow or day after I expect to return to\nyou one of the spinthariscopes fitted with zinc sulfide screen\nwhose natural scintillations are considerably lower than the\nusual specimens of zinc sulfide show. We shall send at the same\ntime a sample of Hammer Special Zinc Sulfide and a sample of Grade\nA, furnished by the Denver Fire Clay Company. The screen which you\nwill find mounted in the instrument is Hammer Special Grade. Grade\nA appears to be somewhat more free from natural scintillations\nthan the Special. After some experimenting we finally found\nthat at least some of the screens which we had prepared and con-\ndemned were not so bad as we had suspected. We found that one of\nthe spinthariscopes which you sent is infected, and this was the one\nwhich we used in our tests. It is barely possible that this instru-\nment became contaminated with a trace of radioactive material in our\nlaboratory. The natural scintillations of the instrument which we\nare planning to send you will be about 50 in three to four minutes - 5 min\nwhen Hammer Special is used, and about 25 when Grade A is used. The\nfluctuations, however, are large and we believe that this is in part\ndue to a slight contamination with radioactive material of the sample\ntested.\nWe have also gone over the data which you sub-\nmitted on the radium content of the excreta in the Dunn case, and we\nhave placed your results alongside of the values found for the radium\ncontent of the excreta in the Dumschott case and we find that your\nvalues are about 10 times as high when expressed as grams radium per\ngrams dry residue as our values for Mrs. Dumschott; 30 I wish to ask\nwhether there is a chance that you may have the decimal point mis-\nplaced in your calculations. Our most active specimen we found to\ncontain 2.8 X 10⁻¹⁰ grams radium per gram, while you report in the\nuniversity OF MISSOURI\nCOLUMBIA\nDEPARTMENT OF CHEMISTRY\n-2-\nMr. H. H. Barker\nDurin Case 5 micrograms per gram which is a value nearly 20 times that\nof our value. We use nitric acid to dissolve the residue.\nI know that you will keep me advised about the\nprogress of the plans for the tests. It seems to me we had better\nsend the spinthariscope and sample of zinc sulfide directly to Dr.\nFlinn so as to avoid a chance for contamination in your office.\nIn case we find the girls active by the gamma ray method of testing,\nwould it not be advisable to check the results against the expired\nair using the large Lind ionization chamber?\nWith very kind regards, I remain\nSincerely yours,\nHaman Schlundt\nHerman Schlundt.\nWe shall also and Flenn\nHS\nSamples of the two grades of phosphorescent\ngns for making new screens.\nC\nb\nHave just s covered that one of the three\nspritharricopes which you sent is an\nwhilition in strument. un to this time\nwe had confined our tests to two of\nthe instru ments, and had left the\nthird in box ant and many\nthanks for this present\nHS."
}