SINCE the discovery of the radioactivity of samarium by Hevesy and Pahl in 19321, several experimenters have examined the emitted radiations in detail2. It is well established that the main radiation consists of I±-particles of range 1.13 ± 0.02 cm., and the experiments of Wilkins and Dempster3 indicate that these particles are emitted by the isotope of mass 148. In addition, however, a number of experimenters claim to have detected particles of longer range, and present some evidence which suggests that they are protons4. Thus Taylor and Dabholkar5, using the photographic technique, found particles, of longer range than the 1.1 cm. group, continuously distributed in range up to a maximum of 3.5 cm. of air and producing a grain-spacing characteristic of protons.