Zinc has been bombarded with 17 Mev alpha-particles and the consequent radioactivity observed. The disintegration products are mainly positrons; the half-lives of the observed activities are 19.8± 0.4 minutes, 37± 1.5 hours, 79± 2 hours and about 195 days. A chemical separation indicates that the first and third of these activities are due to gallium and the remaining two to germanium. The two gallium activities may be respectively assigned to ${\mathrm{Ga}}^{70}$ and ${\mathrm{Ga}}^{67}$. No very definite assignment has been possible, however, with respect to the activities associated with germanium.

• Received 23 August 1938

DOI:https://doi.org/10.1103/PhysRev.54.649