Letters Sent to Dr. Herman Schlundt, October 2, 1928

October 2nd,1928. Dr. Herman Schlundt, University of Missouri, Department of Chemistry, Columbia, No. Dear Dr. Schlundt: The introduction as well as part one of the experimental part of our paper has been received. I have read your subject matter carefully several times and don't know as I can offer mach in the way of constructive criticism. There are one or two points, however, which I wish to call to your attention for further consideration: On page one of the introduction, toward the end of the first paragraph you state that an experienced operator can determine quantitatively one millionth of a microgram of radium. This amount offhand seems almost beyond the range of accurate work, even with delicate instruments - for instance, our experience indicates that it requires approximately five (5) millimicrograns of radium element to cause the leaf to fall one division per second. The quantity indicated by you would be approxinately 1/50 of this amount, which would mean a drift of approximately one dévision per minute for the large chamber Lind electroscope - this it seems to me ie approaching the limit for accurate W ork with this type of instrument. On page 1 of part 1. experimental, at the bottom of page: What would you think of introducing in parenthesis the amont of Tadium which we feel and experienced nan, working under carefully controlled conditions, would give a positive test. As you know Dr. Flinn and I both feel that we can positively detect quantities of less than 5 micrograms, and I can see no reason to expressing in a géneral way the amounts which up to the present time we fel we can detect. I don't know as I would want to go down to a quantity of one microgram, but I do feel that wâth carefully controlled con- ditions and repeated tests that a quantity of two micrograms could be detected. I merely suggest this for consideration. Page 3, Table 1: I presume that the blank space which you have left in this table is intended to be filled in with additional tests which Dr. Flinn has made upon subjects who were or are active. Among this list will have to be included some of those found at the Connecticut plant. Am I correct in this assumption? Page 5, Table 2: In studying this table I was a little surprised to note the variation in the constant - that is the drift increase per microgram where the active source contained different quantities of radium. I do not question your data, as I realize very well it is based upon the figures you obained,But have you any explanation to offer as to the varation