Aston 1922

ISOTOPES[1]

PREFACE

I have undertaken the preparation of this book on isotopes in response to many requests made to me by teachers of physics and chemistry and others working in these subjects that I should publish the results obtained by means of the mass spectrograph in a form more convenient to the public than that in which they first appeared. This is one of the reasons why the space allotted to the inactive isotopes may appear, in the light of the general title of the book, somewhat disproportion- ately large. Another is that the subject of radioactive isotopes really requires a book to itself, and I am in the hope that the inadequacy of my account may stimulate the production of such a volume by hands more competent than mine to deal with this very special and remarkable field of modern science. The logical order of exposition of a scientific subject is to start with the simple and from that build up the more complex. Unfortunately the sequence of events in experimental research is the exact opposite of this so that a compromise must be effected, unless one is content to sacrifice historical treatment altogether. The latter seems very undesirable in a new subject. I have endeavoured in Chapters I, II and IV, and elsewhere when possible, to adhere strictly to the historical order of events even at the cost of some reiteration.

I wish to take this opportunity of expressing my indebted- ness to Mr. C. G. Darwin for his timely criticism and unfailing assistance throughout the work, and also to Mr. R. H. Fowler for help with the proofs. My thanks are also due to Professor Soddy for his diagram of the radioactive isotopes, to Mr. A. J. Dempster for kindly sending me the illustrations of his work, to the proprietors of the Philosophical Magazine and to the Council of the Chemical Society for permission to use the plates and figures of my original papers, and to Messrs. Macmillan & Co., for the diagram of the radioactive transformations.

F. W. Aston

Cambridge,

January, 1922.

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CONTENTS

• • Preface

• Chapter I - Introduction

• Chapter II - The Radioactive Isotopes

• Chapter III - Positive Rays

• Chapter IV - Neon

• Chapter V - The Mass-Spectrograph

• Chapter VI - Analysis of the Elements

• Chapter VII - Analysis of the Elements (Continued)

• Chapter VIII - The Electrical Theory of Matter

• Chapter IX - Isotopes and Atomic Numbers

• Chapter X - The Spectra of Isotopes

• Chapter XI - The Separation of Isotopes

• Appendices

Sub Pages

• Aston 1922/Appendices
• Aston 1922/Chapter 1
• Aston 1922/Chapter 10
• Aston 1922/Chapter 11
• Aston 1922/Chapter 2
• Aston 1922/Chapter 3
• Aston 1922/Chapter 4
• Aston 1922/Chapter 5
• Aston 1922/Chapter 6
• Aston 1922/Chapter 7
• Aston 1922/Chapter 8
• Aston 1922/Chapter 9
• Aston 1922/Contents