Letters Received to H.H. Barker, October 1, 1928

UNIVERSITY OF MISSOURI COLUMBIA DEPARTMENT OF CHEMISTRY October 1, 1928 OCT 3 Mr. H. H. Barker the United States Radium Corporation 535 Pearl Street New York City. My dear Howard: Enclosed herewith is a second, perhaps a third installment of our report, The Detection of Radium in Living Persons. Perhaps we shall be obliged to call a temporary halt for it seems to me that the data in hand on the Scintillation Method of Detecting Radium or Mesothorium will require a little more ex- perimenting. Tomorrow or the day after we hope to return to you two of the spinthariscopes properly fitted with zinc sulfide screens. I fear that there will still be a little residual alpha radiation, although we have used considerable care to keep the zinc sulfide away from high grade material. The magnification of the lens is seven times and the area of the field covered is a circle about 15 mm in diameter. We have in process of construction a spinthariscope in which the lens will be also magnified seven times, but the field covered will be 28 mm in diameter, the Cal length, of course, will be thereby reduced and it will be necessary to mount the lens outside the chamber and fix it so that the zinc sulfide will be fastened to glass through the scintillations can be seen. which Our next step will be to conduct a few experiments on the determination of radium in excreta. Please advise whether the report up to this point will be sufficient to guide Dr. Craver and Dr. Fialla in the tests for radioactivity which are soon to be made on the five patients now under observation. With very kind regards, I remain Sincerely yours, Herman Schlendt Iumder whether the next step should not be HS C b a few pages about the theory of these measurement 2 Dufficate of therestern of report goes takes 7