-particles from a speck of radium
shoot into a chamber and produce therein sufficient ionization by collision to cause an electrometer needle to jump every time one of them entered. These authors measured the total charge as Regener did and, dividing by 2 the charge on each
-particle, they obtained
All determinations of
from radioactive data involve one or the other of these two counts, namely, that of Rutherford and Geiger or that of Regener. Thus, Boltwood and Rutherford[98] measured the total weight of helium produced in a second by a known weight of radium. Dividing this by the number of