d more accurate determination. The nature of the rays emitted is
also given.

[Illustration:

Uranium (8 x 10^9 years) 238.5 -> [alpha]
-> [alpha]
\/
Uranium X (35.5 days) (230.5) -> [beta]&[gamma]
-> ([beta])
\/

\/

\/

Ionium (5 x 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} (?) { -> [al