Values of the half-life of actinouranium are obtained from data on a Morogoro pitchblende and a uraninite from Great Bear Lake, analyzed by von Grosse and Marble, respectively. Computations were made with two extreme values, 0.03 and 0.04, for the actinium "branching ratio" $B$. Half-life values in ${10}^8$ years are:

• Received 10 March 1934

DOI:https://doi.org/10.1103/PhysRev.45.628