The beginning—Radio-active bodies—An atomic property—Discovery of new radio-active bodies—Discovery of Polonium—Discovery of Radium—Other radio-active bodies found
Ionization of Gases—Experimental confirmation—Application of electric field—Size and nature of ions—Photographing the track of the ray—Action of radiations on photographic plates—Discharge of electrified bodies—Scintillations on phosphorescent bodies—Penetrating power—Magnetic deflection—Three types of rays—Alpha rays—Beta rays—Gamma rays—Measurement of radiations—Identifications of the rays
Radio-activity a permanent property—Induced activity—Discovery of Uranium X—Conclusions drawn—Search for new radio-active bodies—Methods of investigation—Nature of the radiations—Life-periods—Equilibrium series
Disintegrating of the elements—Identification of the rays—The alpha rays—Alpha rays consist of solid particles—Electrical charge—Helium formed from alpha particles—Discovery of Helium—Characteristics of Helium—Table of constants
Properties of Radium—Energy evolved by radium—Necessity for a disintegration theory—Disintegration theory—Constitution of the atom—Rutherford's atom—Scattering of alpha particles—Stopping power of substances
Influence upon chemical theory—The periodic system—Basis of the periodic system—Influence of positive nucleus—Determination of the atomic number—Use of X-ray spectra—Changes caused by ray-emission—Atomic weight losses—Lead the end product—Changes of position in the periodic system—Changes from loss of beta particles—Isotopes—Radio-activity in nature—Radio-active products in the earth's crust—Presence in air and soil waters—Cosmical radio-activity
