Report, July 27, 1925

Report of Tests Made on Samples Submitted by Dr. Flinn, July 20, 1925. Preliminary examination of the specimens infiented that the samples marked 1, 2, 3, and B, all in brown bottles, were suffic- iently radio active for gamma ray measurements. Samples were therefore hennetically sealed in a standard type of tube and allowed to tand for about five weeks, afetr which a series of readings were ande Bample 1, brown bottle, contains the equivalent of approximately 1.55 micro grams of radium element per Sample 2, brown bottle, con ains the equivalent of approxiuately 1.75 micro grans of redium element per Sample 3, brown bottle, contains the equivalent of approxisately 0.02 micro grams of radium element per gram. Sample B, brown bottle, contains the equivalent of approxinately 0.23 micro scans of r adium element per gram. Inasmich as the quantity of radium or nesothorium in the remain- ins samples, with the exception of the urine sanples, is very snall it has been somewhat difficult to definitely establish just what their activity amounter to in terms of radium element. In some instances the activity is so small that it is quite possible that the activitating agent was introluced by contam- ination unless the operator who put the samples up used the utmost of caution. It would have bean a good idea had a emple of aome of the organs of an animal not t reated with the zine sulphide been included, as that would have served as a check for contamination, or the possibility of a slight ionizing power that may be characteristio of the material as a result of the method of treating. Perhpas it will be advisable to describe in brief the method I used in testing the following samples together with the data obtained, 8.8 that may give a more concrete idea of the difficult- iss involved in ascertaining the quantity of activating agant contained per sram. A specially constructed type of alpha ray electroscope was used. First, the natural drift, that is, the time required for the quartz fibre in the electroscope to pass over a definite number of divisions in the eyepiece, was determined withthe physical conditions in the instrument the same as when the sample was to be read. The sample was then introduced and the time required