CONTENTS
ESSAY I
ON THE SPECTRUM OF HYDROGEN
Empirical spectral laws
Laws of temperature radiation
The nuclear theory of the atom
Quantum theory of spectra
Hydrogen spectrum
The Pickering lines
Other spectra


ESSAY II
ON THE SERIES SPECTRA OF THE ELEMENTS
I. Introduction
II. General Principles of the Quantum Theory of Spectra
Hydrogen spectrum
The correspondence principle
General spectral laws
Absorption and excitation of radiation
III. Development of the Quantum Theory of Spectra
Effect of external forces on the hydrogen spectrum
The Stark effect
The Zeeman effect
Central perturbations
Relativity effect on hydrogen lines
Theory of series spectra
Correspondence principle and conservation of angular momentum
The spectra of helium and lithium
Complex structure of series lines
IV. Conclusion


ESSAY III
THE STRUCTURE OF THE ATOM AND THE PHYSICAL AND CHEMICAL PROPERTIES OF THE ELEMENTS
I. Preliminary
The nuclear atom
The postulates of the quantum theory
Hydrogen atom
Hydrogen spectrum and X-ray spectra
The fine structure of the hydrogen lines
Periodic table
Recent atomic models
II. Series Spectra and the Capture of Electrons by Atoms
Arc and spark spectra
Series diagram
Correspondence principle
III. Formation of Atoms and the Periodic Table
First Period. Hydrogen-Helium
Second Period. Lithium-Neon
Third Period. Sodium-Argon
Fourth Period. Potassium-Krypton
Fifth Period. Rubidium-Xenon
Sixth Period. Caesium-Niton
Seventh Period
Survey of the periodic table
IV. Reorganization of Atoms and X-Ray Spectra
Absorption and emission of X-rays and correspondence principle
]X-ray spectra and atomic structure
Classification of X-ray spectra
Conclusion