Report, no date

EXPERIMENTAL DETERMINATION OF THE RADIUM PROSENT IN LIVING PERSONS. Calibration of Gamma Ray instrument. Mr. Barker and Dr. Flinn worked out method of calibrating the gamma ray electroscope used for detecting radio- active elements in the living persons. They find that a net discharge of the in- strument of 0.0018 d.p.sec. represents 10 microgrems of radium, distributed in the body. This value for the calibration constant applies when the instrument is put up close to the middle of back of subject and the net drift of the leaf of the elec- troscope is determined and expressed in divisions per second. TO get this value gamma ray measurements were made as just stated on a radioactive subject a faw months before death. Adter death the radium content of the skeleton and body the parts was determined by the amanation method, and the total radium content of per- whane A son computed Net discharge for radioactive person/0.018 X 10 = micrograms radium in living person. In this way it was found that 10 micrograms of radium in a living person produced a discharge of 0.0018 d.p. sec. in the instrument whence an experimental value e.g. of 0.0072 d.p.sec. for the net drift would represent 40 micrograms of radio-activi- ty in the individual under test. It may be of interest in this point to mention that two ampoules of radium solution of five micrograms each likewise produce a net drift of 020018 d.p.sed. when placed in the vest pockets of a non-radioactive person of average size. Let us compute next the quantity of emanation that would be expired con- tinuously from a radio-active person with 40 micrograms of radium present: First let us generously assume that all of the emanation produced is given off in the lungs to the expired air. Since 1 g radium element produces constantly per second 2.1 x 10-6 curies of emanation, 1.0., Ra.Em. accumulates at the rate of