The study of radioactivity was pursued with great ability not only by the Curies and A.
It requires a radium salt of high radioactivity to be at all comparable in effectiveness with a good water-dropper.
The study of radium and radioactivity led before long to the further remarkable knowledge that these so-called radioactive materials project into surrounding space particles or corpuscles, some of which are identical with those projected from the cathode in a high vacuum tube, together with others of a different nature.
The radioactivity is denoted by A, and A = signifies that the potential of the dissipation apparatus fell I volt in an hour per metre of wire introduced.
Turning to the study of radioactivity, he noticed its association with the minerals which yield helium, and in support of the hypothesis that that gas is a disintegration-product of radium he proved in 1903 that it is continuously formed by the latter substance in quantities sufficiently great to be directly recognizable in the spectroscope.