“
In the... various disintegration series of uranium, thorium and actinium, every degree of atomic instability is encountered. The average life varies from... [~]1010 years, for... primary... uranium and thorium, down to... a minute.., the limit beyond which the chemical character cannot be investigated. But by physical methods... down to... 1/350 second have been... in evidence, and two, of the order... 10-6 and 10-11 second, are indirectly inferred.
— FREDERICK SODDY