THORIUM SERIES
| Element | Atomic Weight | T (average time-period—half transformed) | Rays (given out in each decomposition) |
| Thorium | 232.1 | 2.2 × 1010 yrs. | Alpha |
| Mesothorium I | 228 | 6.7 yrs. | Beta, Gamma |
| Mesothorium II | 228 | 6.2 hrs. (?) | Beta, Gamma |
| Radio-thorium | 228 | 1.90 yrs. (?) | Alpha |
| Thorium X | 224 | 3.64 days | Alpha |
| Thorium (Emanation) | 220 | 54 sec. (?) | Alpha |
| Thorium A | 216 | .14 sec. (?) | Alpha |
| Thorium B | 216 | 10.6 hrs. (?) | Beta, Gamma |
| Thorium C | 212 | 60 min. (?) | Alpha |
| Thorium D | 208 | 3.2 min. (?) | Beta, Gamma |
| Thorium E (End-product thorium-lead) | 208 | ............... | ............... |