The consecutive disintegration series, with the half-value periods, for the uranium and thorium series as given by Soddy are seen in the following tables. They are probably subject to some changes on further and more accurate determination. The nature of the rays emitted is also given. [Illustration: Uranium (8 × 10^9 years) 238.5 -> [alpha] -> [alpha] \/ Uranium X (35.5 days) (230.5) -> [beta]&[gamma] -> ([beta]) \/ \/ \/ Ionium (5 × 10^4 to 10^6 years) (230.5) -> [alpha] \/ Radium (2,500 years) 226.4 -> [alpha] \/ Emanation (5.57 days) (222.4) -> [alpha] \/ Radium A (4.3 minutes) (218.4) -> [alpha] \/ Radium B (38.5 minutes) (214.4) -> ([beta]) \/ Radium C_{1} (28.1 minutes) { (214.4) -> [alpha] { -> [beta]&[gamma] { \/ Radium C_{2} (1.9 minutes) { (210.4) -> [beta]&[gamma] \/ Radium D (24 years?) (210.4) -> ([beta]) \/ Radium E (7.25 days) (210.4) -> [beta]&[gamma] \/ Radium F (Polonium 202 days) (210.4) -> [alpha] \/ Radium G (probably lead) (206.8) Actinium (?) \/ Radio-Actinium (28.1 days) -> [alpha] -> ([beta]) \/ Actinium X (15 days) -> [alpha] \/ Emanation (5.6 seconds) -> [alpha] \/ Actinium A (0.0029 second) -> [alpha] \/ Actinium B (52.1 minutes) -> ([beta]) \/ Actinium C_{1} (3.10 mins.) { -> [alpha] { \/ Actinium C_{2} (?) { -> [alpha] \/ Actinium D (7.4 minutes) -> [beta]&[gamma] \/ Actinium E (unknown)