Letters Received to H.H. Barker, October 15, 1928

UNIVERSITY OF MISSOURI RECEIVED COLUMBIA OCT 17 1928 DEPARTMENT OF CHEMISTRY October 15, 1928 Mr. H. H. Barker United States Radium Corporation RADIC 535 Pearl Street MAYERIAL CORP. New York City, New York My dear Howard: First of all let me thank you for your notes on progress of tests by the Commission, as per yours of October 11, 1928. Enclosed herewith is another installment of our report. I agree fully with you about getting published the material now in hand. To this end I have finished up the essentials of the theoretical part. Let us then try to assemble the material now in hand and put it in final form. In the meantime, could we not hold the fort by indicating in our title, as is quite often done, that this is the first contribution on the subject. The title would then be: THE DETECTION AND ESTIMATION OF PADIUM AND MESOTHORIUM IN LIVING PERSONS. I. Then on the page giving the outline insert this sentence just before the heading, "GAMMA RAY MSTHOD": The experiments conducted on the radioactivity of excreta and the detection of radio- activity in expired air by the scintillation method will be reported in a second con- tribution." Subject D, as appears in our notes, is H. H. Barker, with clothes on, tested August 24, 1928. Perhaps this result should not be included after all. I hope that you and DI. Flinn will add to Table 1, page 3. Now let me take un some of the suggestions in your letter of October 2, 1928. l. Limit of Emanation Method: I have gone the limit in my state- ment on page 1 of introduction but I hope not too far. In the Lind electroscope 7 x 10- curies Radon - 7000 x10th grams, produce a drift of 1 division per second or 1 curie produces a net drift of 0.00014 divisions per second. In an instrument of smaller electrostatic capacity like a Wulf quartz fiber, one ullicurie would pro- duce a drift three to ten times as great which is about the same as the value we found for gamma ray instrument when 5 micrograms standard was used. When we tested you on August 24, we found a net drift of 0.00033 divisions per second, which we re- port as 4 ug: But I am not adverse to making this, " a few micrograms in place of 1 microgram; but when you go down to 2 M for Wulf instrument by gamma ray method, please remember the net drift increase will be only 0.00012 divisions per second.