Having now briefly reviewed the nature of the rays arising in
radioactive substances and the rationale of their influence, we
must turn to more especially practical considerations.
The Table given opposite shows that radium itself is responsible
for a- and ß-rays only. It happens that
252
Period in whioh ½ element is transformed.
URANIUM 1 & 2 { a 6 } x 109 years.
URANIUM X { a ß } 24.6 days.
IONIUM { a 8 } x 104 years.
RADIUM { a ß } 2 x 102 years.
EMANATION { a } 8.85 days.
RADIUM A { a 8 } minutes.