ABSTRACT
The results of an examination of the wave-lengths of the soft γ rays from radium B, for angles of reflexion from rock-salt between 8° and 16°. Direct evidence was obtained that the strong lines of the γ ray spectrum of radium B were identical with the corresponding lines in the X-ray spectrum of lead thus confirming the hypothesis that radium B and lead have identical physical and chemical properties, although their atomic weights differ probably by seven units. Considering the fact that no attempt was made to cut off the effect of the general γ radiation on the photographic plate, the sharpness with which the bands show up is very remarkable. Results of this kind bring out clearly the large amount of the radiation that is scattered when passing through the crystal at proper reflexion angle. In order to overcome this difficulty, recourse was also had to another method involving the measurements of the dark bands arising from reflexion.
