important observation that the curve of decay C, corresponding to that shown in Fig. 88, for a long exposure, could be accurately expressed by an empirical equation of the form
where λ2 = 5·38 × 10-4 (sec)-1 and λ3 = 4·13 × 10-4 (sec)-1, and α = 4·20 is a numerical constant.
I have found that within the limit of experimental error this equation represents the decay of excited activity of radium for a long exposure, measured by the β rays. The equation expressing the decay of activity, measured by the α rays, differs considerably from this, especially in the early part of the