Chapter II: Preface: To the Second Edition

I feel that some apology is due to my readers for bringing out at such an early date a new edition which includes so much new material, and in which the rearrangement is so extensive as to constitute almost a new work. Though only a year has passed since the book first made its appearance, the researches that have been carried out in that time have been too numerous and of too important a character to permit the publishing of a mere reprint, unless the author were to relinquish his purpose of presenting the subject as it stands at the present moment.

The three new chapters which have been added possibly constitute the most important change in the work. These chapters include a detailed account of the theory of successive changes and of its application to the analysis of the series of transformations which occur in radium, thorium, and actinium.

The disintegration theory, which was put forward in the first edition as an explanation of radio-active phenomena, has in these later researches proved to be a most powerful and valuable method of analysing the connection between the series of substances which arise from the transformation of the radio-elements. It has disclosed the origin of radium, of polonium and radio-tellurium, and of radio-lead, and now binds together in one coherent whole the large mass of apparently heterogeneous experimental facts in radio-activity which have been accumulating since 1896. The theory has received a remarkable measure of verification in the past year, and, in many cases, has offered a quantitative as well as a qualitative explanation of the connection between the various properties exhibited by the radio-active bodies. In the light of this evidence, radio-activity may claim to have assumed the position of an independent subject, though one with close affinities to physics on the one hand and to chemistry on the other.

The present edition includes a large amount of new material relating to the nature and properties of the radiations and the emanations. In the limits of this book, it would have been found impossible, even had it been thought desirable, to include more than a brief sketch of the physiological effects of the rays. The literature on this subject is already large, and is increasing rapidly. For reasons of space, I have not been able to refer more than briefly to the mass of papers that have appeared dealing with the examination of various spring and well waters, sediments, and soils, for the presence of radio-active matter.

In order to make the book more self-contained, a short account has been given in Chapter II of the magnetic field produced by an ion in motion, of the action of an external magnetic and electric field upon it, and of the determination of the velocity and mass of the particles constituting the cathode stream.

Two appendices have been added, one giving an account of some work upon the α rays which was completed too late for inclusion in the subject matter of the book, and the other containing a brief summary of what is known in regard to the chemical constitution of the various radio-active minerals, the localities in which they are found, and their probable geologic age. For the preparation of the latter, I am indebted to my friend Dr Boltwood of New Haven, who, in the course of his researches, has had occasion to analyse most of these minerals in order to determine their content of uranium and radium. I hope that this account of radio-active minerals will prove of value to those who are endeavouring to elucidate the connection between the various radio-active substances and the inactive products which arise from their transformation.

For the convenience of those who have read the first edition, a list of the sections and chapters which contain the most important additions and alterations is added below the table of contents.

The writing of a complete account of a subject like radio-activity, in which so much new work is constantly appearing, has been a matter of no little difficulty. Among other things it has involved a continuous revision of the work while the volume was passing through the press.

I wish to express my thanks to my colleague Professor Harkness for the care and trouble he has taken in revising the proofs and for many useful suggestions; also to Mr R. K. McClung for his assistance in correcting some of the proofs and in preparing the index.

E. R.

MCGILL UNIVERSITY,
MONTREAL,
_9 May, 1905_.

Transcriber’s Note:

The plain text version of this ebook includes complex mathematical formulas in TeX notation. These formulas are enclosed between double dollar signs. The HTML version includes the same formulas rendered in their original form.

ERRATA.

Transcriber’s Note:

These corrections have been applied to the text in the book.

page 48, line 24 section 218 should read section 284
„ 77, last line „ 263 „ „ „ 270
„ 123, 5th line from bottom „ 254 „ „ „ 261
„ 124, 10th „ „ „ „ 246 „ „ „ 253
„ 151, line 3 „ 228 „ „ „ 229
„ 156, 13th line from bottom „ 261 „ „ „ 268
„ 200, line 9 „ 246 „ „ „ 253
„ 216, line 3 „ 260 „ „ „ 267
„ 184, at the top of 5th column of table the letter γ should be
inserted.

TABLE OF CONTENTS.

I. Radio-active Substances 1

II. Ionization Theory of Gases 31

III. Methods of Measurement 82

IV. Nature of the Radiations 108

V. Properties of the Radiations 201

VI. Continuous Production of Radio-active Matter 218

VII. Radio-active Emanations 238

VIII. Excited Radio-activity 295

IX. Theory of Successive Changes 325

X. Transformation Products of Uranium, Thorium and Actinium 346

XI. Transformation Products of Radium 371

XII. Rate of Emission of Energy 418

XIII. Radio-active Processes 437

XIV. Radio-activity of the Atmosphere and of Ordinary Materials 501

Appendix A. Properties of the α Rays 543

Appendix B. Radio-active Minerals 554

Index 559

Plate (Fig. 46A: Spectrum of Radium Bromide) _to face p._ 206

* * * * *

For the convenience of the reader, the sections and chapters which contain mostly new matter, or have been either partly or wholly rewritten, are appended below.

Chap. I. Sections 18, 20–23.
„ II. „ 48–52.
„ III. „ 69.
„ IV. „ 83–85, 92, 93, 103, 104, 106–108, 111, 112.
„ V. „ 115, 117, 119, 122.
„ VII. „ 171–173.
„ VIII. „ 182–184, 190.
„ IX-XIV. Mostly rewritten.

ABBREVIATIONS OF REFERENCES TO SOME OF THE JOURNALS.

_Ber. d. deutsch. Chem. Ges._ Berichte der deutschen chemischen
Gesellschaft. Berlin.

_C. R._ Comptes Rendus des Séances de l’Académie des Sciences.
Paris.

_Chem. News._ Chemical News. London.

_Drude’s Annal._ Annalen der Physik. Leipzig.

_Phil. Mag._ Philosophical Magazine and Journal of Science. London.

_Phil. Trans._ Philosophical Transactions of the Royal Society of
London.

_Phys. Rev._ Physical Review. New York.

_Phys. Zeit._ Physikalische Zeitschrift.

_Proc. Camb. Phil. Soc._ Proceedings of the Cambridge Philosophical
Society. Cambridge.

_Proc. Roy. Soc._ Proceedings of the Royal Society of London.

_Thèses-Paris._ Thèses présentées à la Faculté des Sciences de
l’Université de Paris.

_Wied. Annal._ Annalen der Physik. Leipzig.