VOLUME 1 Introduction 5 Atomic Weights 6 Electricity 11 Units of Electricity 11 Cathode Rays 13 Radioactivity 17 The Structure of the Atom 25 Atomic Numbers 30 Isotopes 35 Energy 47 The Law of Conservation of Energy 47 Chemical Energy 50 Electrons and Energy 54 The Energy of the Sun 55 The Energy of Radioactivity 57 VOLUME 2 Mass and Energy 69 The Structure of the Nucleus 75 The Proton 75 The Proton-Electron Theory 76 Protons in Nuclei 80 Nuclear Bombardment 82 Particle Accelerators 86 The Neutron 92 Nuclear Spin 92 Discovery of the Neutron 95 The Proton-Neutron Theory 98 The Nuclear Interaction 101 Neutron Bombardment 107