The half-lives of six gamma-emitting nuclides were determined by comparison with radium standards, using a lead-shielded ionization chamber. The following results were obtained: ${\mathrm{Sc}}^{46}$: 83.89±0.12 days; ${\mathrm{Co}}^{60}$: 5.24±0.03 years; ${\mathrm{Zn}}^{65}$: 243.5±0.8 days; ${\mathrm{Ag}}^{110m}:252.5\mathrm{}\pm 1.5$ days; ${\mathrm{Cs}}^{134}$: 2.07±0.02 years; ${\mathrm{Eu}}^{152,154}$: 12.2±0.2 years. The errors quoted are twice the standard deviation calculated from a least-squares analysis.

• Received 28 November 1956

DOI:https://doi.org/10.1103/PhysRev.105.1539