Letters Received to H.H. Barker, January 21, 1931

UNIVERSITY OF MISSOURI COLUMBIA DEPARTMENT OF CHEMISTRY January 21, 1931 JAN 23 1931 Mr. H. H. Barker United States Radium Corporation 535 Pearl Street New York City, New York My dear Barker: Naturally when it came to the question of the quantity of radium that can be detected in a living subject by the gamma ray method, both Dr. Lind and myself called for the experimental data from which the calculations were made. Let me give you an example: The record shows that the normal drift of the instrument was two divisions in 40 minutes;with the sub- ject under test the observed drift was two divisions in 32 min- utes. The constant of the instrument is assumed as .00015 +. The natural drift in this case is .00083 and the observed drift with subject is .00104, leaving a difference of .00021 from which it shows that the subject contains about 1.4 micrograms of radio- active substance. As I recall it most of the dial painters who have worked since 1926 contained but very small traces of radium and in many cases practically none. The occasional high values such as 6 to 8 micrograms are very limited and it seems to me must be due to some accidental occurrence. During the next few days I expect to receive from Dr. Leake who succeeded Dr. Thompson on the Committee, a revised copy of the report and I shall be glad to mail this to you for reading. As I recall it now the statistical curve for the increase of activity in the workers with time runs about one to two micrograms per year averaged over all the workers. The transfer-press method of applying luminous paint is considered a little more hazardous than regular dial painting because of the larger quantities of paint used at any one time. There is more danger of dust because as now in opera- tion the excess paint after drying is scraped off and thus finds its way into the air in the immediate vicinity of the workers. I expect to write to you again within the next days. Our semester examinations are now in progress and so we are very busy with the closing work of the semester. Sincerely yours, Thig letter was dictated about a week ago- Herman Schlundt HS:AS Hermen Schlundt.