Notes
Watts, Phil. Mag. July, 1903; August, 1904.
Runge, Phil. Mag. December, 1903.
Debierne, C. R. 129, p. 593, 1899; 130, p. 206, 1900.
Giesel, Ber. d. D. Chem. Ges. p. 3608, 1902; p. 342, 1903.
Debierne, C. R. 139, p. 538, 1904. Miss Brooks, Phil. Mag. Sept. 1904. Giesel, Phys. Zeit. 5, p. 822, 1904. Jahrbuch. d. Radioaktivität, no. 4, p. 345, 1904.
Hofmann, Gonder and Wölfl, Annal. d. Phys. No. 13, p. 615, 1904.
Hofmann and Zerban, Ber. d. D. Chem. Ges. No. 12, p. 3093, 1903.
Baskerville and Zerban, Amer. Chem. Soc. 26, p. 1642, 1904.
CHAPTER II. IONIZATION THEORY OF GASES.
J. J. Thomson and Rutherford, Phil. Mag. Nov. 1896.
The word ion has now been generally adopted in the literature of the subject. In using this word, it is not assumed that the ions in gases are the same as the corresponding ions in the electrolysis of solutions.
A minute current is observed between the plates even if no radio-active matter be present. This has been found to be due mainly to a slight natural radio-activity of the matter composing them. (See chapter XIV.)
This nomenclature has arisen from the similarity of the shape of the current-voltage curves to the magnetization curves for iron. Since, on the ionization theory, the maximum current is a result of the removal of all the ions from the gas, before recombination occurs, the terms are not very suitable. They have however now come into general use and will be retained throughout this work.
Some difference of opinion has been expressed as to the value of V required to produce ions at each collision. Townsend considers it to be about 20 volts; Langevin 60 volts and Stark about 50 volts.
Rutherford, Phil. Mag. Jan. 1899.
Rutherford, Phil. Mag. Jan. 1899.
Strutt, Phil. Trans. A, p. 507, 1901 and Proc. Roy. Soc. p. 208, 1903.
McClung, Phil. Mag. Sept. 1904.
A simple and excellent account of the effects produced by the motion of a charged ion and also of the electronic theory of matter was given by Sir Oliver Lodge in 1903 in a paper entitled “Electrons” (Proceedings of the Institution of Electrical Engineers, Part 159, Vol. 32, 1903). See also J. J. Thomson’s Electricity and Matter (Scribner, New York, 1904).
J. J. Thomson, Phil. Mag. April, 1887.
Heaviside, Collected Papers, Vol. II. p. 514.
Searle, Phil. Mag. Oct. 1897.
Abraham, Phys. Zeit. 4, No. 1 b, p. 57, 1902.
A full account of the path described by a moving ion under various conditions is given by J. J. Thomson, Conduction of Electricity in Gases (Camb. Univ. Press, 1903), pp. 79–90.
J. J. Thomson, Phil. Mag. p. 293, 1897.
Lenard, Annal. d. Phys. 64, p. 279, 1898.
Kaufmann, Annal. d. Phys. 61, p. 544; 62, p. 596, 1897; 65, p. 431, 1898.
Simon, Annal. d. Phys. 69, p. 589, 1899.
A complete discussion of the various methods employed to measure the velocity and mass of electrons and also of the theory on which they are based will be found in J. J. Thomson’s Conduction of Electricity through Gases.
Goldstein, Berlin Sitzber. 39, p. 691, 1896; Annal. d. Phys. 64, p. 45, 1898.
Wien, Annal. d. Phys. 65, p. 440, 1898.
Larmor, Phil. Mag. 44, p. 593, 1897.
J. J. Thomson, Phil. Mag. Feb. 1897.
Barkla, Phil. Mag. June, 1903.
CHAPTER III. METHODS OF MEASUREMENT.
Soddy, Trans. Chem. Soc. Vol. 81, p. 860, 1902.
Wilson, Proc. Roy. Soc. Vol. 68, p. 152, 1901.
If the apparatus is required to be air-tight, the gold-leaf system can be charged by means of a piece of magnetized steel wire, which is made to touch the rod R by the approach of a magnet.
It is sometimes observed that the motion of the gold-leaf, immediately after charging, is irregular. In many cases, this can be traced to air currents set up in the electroscope in consequence of unsymmetrical heating by the source of light used for illumination.
Wilson, Proc. Camb. Phil. Soc. Vol. 12, Part II. 1903.
Walker, Phil. Mag. Aug. 1903.
Strutt, Phil. Trans. A, p. 507, 1901.
Dolezalek, Instrumentenkunde, p. 345, Dec. 1901.
It is very desirable that care should be taken not to release large quantities of the radium emanation inside a laboratory. This emanation has a slow rate of decay and is carried by currents of air throughout the whole building and finally leaves behind an active deposit of very slow rate of change (see chapter XI.). Eve (Nature, March 16, 1905) has drawn attention to the difficulty of making refined radio-active measurements under such conditions.
J. J. Thomson, Phil. Mag. 46, p. 537, 1898.
Bronson, Amer. Journ. Science, Feb. 1905.
J. and P. Curie, C. R. 91, pp. 38 and 294, 1880. See also Friedel and J. Curie, C. R. 96, pp. 1262 and 1389, 1883, and Lord Kelvin, Phil. Mag. 36, pp. 331, 342, 384, 414, 453, 1893.
CHAPTER IV. NATURE OF THE RADIATIONS.
In an examination of uranium the writer (Phil. Mag. p. 116, Jan. 1899) found that the rays from uranium consist of two kinds, differing greatly in penetrating power, which were called the α and β rays. Later, it was found that similar types of rays were emitted by thorium and radium. On the discovery that very penetrating rays were given out by uranium and thorium as well as by radium, the term γ was applied to them by the writer. The word “ray” has been retained in this work, although it is now settled that the α and β rays consist of particles projected with great velocity. The term is thus used in the same sense as by Newton, who applied it in the Principia to the stream of corpuscles which he believed to be responsible for the phenomenon of light. In some recent papers, the α and β rays have been called the α and β “emanations.” This nomenclature cannot fail to lead to confusion, since the term “radio-active emanation” has already been generally adopted in radio-activity as applying to the material substance which gradually diffuses from thorium and radium compounds, and itself emits rays.
It is presumed that the results were corrected, if necessary, for the discharging action due to the ionized gas, although no direct mention of this is made in the paper by Seitz.
Strutt, Phil. Trans. A, p. 507, 1901.
Crookes, Proc. Roy. Soc. 1902. Chem. News, 85, p. 109, 1902.
Mme Curie, C. R. 130, p. 76, 1900.
Rutherford, Phil. Mag. Feb. 1903. Phys. Zeit. 4, p. 235, 1902.
Further experimental results bearing on this important question are given in an Appendix to this book.
Bakerian Lecture, Phil. Trans. A, p. 169, 1904.
Strutt, Phil. Mag. Aug. 1904.
J. J. Thomson, Proc. Camb. Phil. Soc. 13, Pt. I. p. 39, 1905. Nature, Dec. 15, 1904.
Rutherford, Nature, March 2, 1905. J. J. Thomson, Nature, March 9, 1905.
An interesting side-light is thrown on this question by the experiments described in Appendix A of this book.
Rutherford and Miss Brooks, Phil. Mag. July 1902.
In order to obtain a thin layer, the compound to be tested is ground to a fine powder and then sifted through a fine gauge uniformly over the area, so that the plate is only partially covered.
Rutherford, Phil. Mag. Jan. 1899.
Owens, Phil. Mag. Oct. 1899.
Rutherford and Miss Brooks, Phil. Mag. July, 1900.
Since the ionization at any point above the plate is the resultant effect of the α particles coming from all points of the large radio-active layer, λ is not the same as the coefficient of absorption of the rays from a point source. It will however be proportional to it. For this reason λ is called the “absorption constant.”
Townsend, Phil. Mag. Feb. 1901.
Durack, Phil. Mag. July 1902, May 1903.
Bragg and Bragg and Kleeman, Phil. Mag. Dec. 1904.
In a recent paper (Phil. Mag. Feb. 1905), McClelland has, in the main, confirmed the experimental results obtained by Eve. An electrometer was used instead of an electroscope. He finds, in addition, that the amount of secondary radiation depends on the angle of incidence of the primary rays, and is greatest for an angle of 45°. In a letter to Nature (Feb. 23, p. 390, 1905), he states that more recent experiments have shown that the amount of secondary radiation from different substances is a function of their atomic weights rather than of their densities. In every case examined, the amount of secondary radiation increases with the atomic weight, but is not proportional to it.
Kunz and Baskerville, Amer. Journ. Science XVI. p. 335, 1903.
See Nature, p. 523, March 31, 1904.
Crookes, Proc. Roy. Soc. 74, p. 47, 1904.
Kunz and Baskerville, Science XVIII, p. 769, Dec. 18, 1903.
Beilby in a recent communication to the Royal Society (Feb. 9 and 23, 1905) has examined in some detail the production of phosphorescence by the β and γ rays of radium and has put forward a theory to account for the different actions observed.
Huggins, Proc. Roy. Soc. 72, pp. 196 and 409, 1903.
The spark spectrum of the radium bromide showed the H and K lines of calcium and also faintly some of the strong lines of barium. The characteristic lines of radium of wave-lengths 3814·59, 3649·7, 4340·6 and 2708·6, as shown by Demarçay and others are clearly shown in the figure. The strong line of wave-length about 2814 is due to radium.
Giesel, Ber. d. D. Chem. Ges. 37, p. 1696, 1904.
Hartmann, Phys. Zeit. 5, No. 18, p. 570, 1904.
In a recent paper, Giesel (Ber. d. D. Chem. Ges. No. 3, p. 775, 1905) has shown that the bright lines are due to didymium, which is present as an impurity. Exposure of didymium to the radium rays also causes the appearance of the lines.
Wiedemann and Schmidt, Wied. Annal. 59, p. 604, 1895.
Wiedemann, Phys. Zeit. 2, p. 269, 1901.
Elster and Geitel, Annal. d. Phys. 69, p. 673, 1899.
Willons and Peck (Phil. Mag. March, 1905) found that under some conditions, especially for long sparks, the rays of radium hindered the passage of the spark.
Hemptinne, C. R. 133, p. 934, 1901.
Himstedt, Phys. Zeit. p. 476, 1900.
Henning, Annal. d. Phys. p. 562, 1902.
Kohlrausch and Henning, Verh. Deutsch. Phys. Ges. 6, p. 144, 1904.
Hardy and Anderson, Proc. Roy. Soc. 72, p. 393, 1903.
CHAPTER VI. CONTINUOUS PRODUCTION OF RADIO-ACTIVE MATTER.
Crookes, Proc. Roy. Soc. 66, p. 409, 1900.
Becquerel, C. R. 131, p. 137, 1900; 133, p. 977, 1901.
Rutherford and Soddy, Phil. Mag. Sept. and Nov. 1902. Trans. Chem. Soc. 81, pp. 321 and 837, 1902.
Rutherford and Soddy, Phil. Mag. Sept. 1902.
The general method of regarding the subject would be unchanged, even if it were proved that the radio-activity of thorium is not due to thorium at all but to a small constant amount of a radio-active impurity mixed with it.
Rutherford and Soddy, Phil. Mag. Sept. 1902.
CHAPTER VII. RADIO-ACTIVE EMANATIONS.
Owens, Phil. Mag. p. 360, Oct. 1899.
Rutherford, Phil. Mag. p. 1, Jan. 1900.
Rossignol and Gimingham, Phil. Mag. July, 1904.
As regards date of publication, the priority of the discovery of “excited activity” belongs to M. and Mme. Curie. A short paper on this subject, entitled “Sur la radioactivité provoquée par les rayons de Becquerel,” was communicated by them to the Comptes Rendus, Nov. 6, 1899. A short note was added to the paper by Becquerel in which the phenomena of excited activity were ascribed to a type of phosphorescence. On my part, I had simultaneously discovered the emission of an emanation from thorium compounds and the excited activity produced by it, in July, 1899. I, however, delayed publication in order to work out in some detail the properties of the emanation and of the excited activity and the connection between them. The results were published in two papers in the Philosophical Magazine (Jan. and Feb. 1900) entitled “A radio-active substance emitted from thorium compounds,” and “Radio-activity produced in substances by the action of thorium compounds.”
F. von Lerch, Annal. d. Phys. 12, p. 745, 1903.
Pegram, Phys. Review, p. 424, Dec. 1903.
Miss Gates, Phys. Review, p. 300, 1903.
A more complete examination of the effect of temperature on the excited activity of thorium has been made by Miss Slater (section 207).
Rutherford, Phil. Mag. Feb. 1900.
Giesel, Ber. d. D. Chem. Ges. 36, p. 342, 1903.
Debierne, C. R. 136, pp. 446 and 671, 1903; 138, p. 411, 1904.
CHAPTER IX. THEORY OF SUCCESSIVE CHANGES.
Ramsay, Proc. Roy. Soc. p. 470, June, 1904; C. R. 138, June 6, 1904.
Phil. Mag. February, 1904.
CHAPTER X. TRANSFORMATION PRODUCTS OF URANIUM, THORIUM, AND ACTINIUM.
Soddy, Trans. Chem. Soc. 81, p. 460, 1902.
Pegram, Phys. Rev. p. 424, December, 1903.
Miss Slater, Phil. Mag. 1905.
von Lerch, Ann. de d. Phys. November, 1903.
The ‘rayless change’ certainly does not give out α rays, and special experiments showed that no appreciable amount of β rays were present. On the other hand, the second change gives out all three types of rays.
Miss Brooks, Phil. Mag. Sept. 1904.
Miss Gates, Phys. Rev. p. 300, 1903.
Miss Brooks, Nature, July 21, 1904.
Rutherford, Phil. Mag. Nov. 1904. Nature, p. 341, Feb. 9, 1905.
Rutherford, Nature, p. 341, Feb. 9, 1905.
Marckwald (Ber. d. D. Chem. Ges. p. 591, 1905) has recently found that the activity of his radio-tellurium falls to half value in 139 days.
Eve, Nature, March 16, 1905.
J. J. Thomson, International Electrical Congress, St Louis, Sept. 1904.
Rutherford and Soddy, Phil. Mag. p. 582, 1902; pp. 453 and 579, 1903.
Ramsay and Soddy, Nature, July 16, p. 246, 1903. Proc. Roy. Soc. 72, p. 204, 1903; 73, p. 346, 1904.
Curie and Dewar, C. R. 138, p. 190, 1904. Chem. News, 89, p. 85, 1904.
Strutt, Phil. Mag. June, 1903.
Elster and Geitel, Phys. Zeit. 4, No. 19, p. 522, 1903. Chem. News, July 17, p. 30, 1903.
CHAPTER XIV. RADIO-ACTIVITY OF THE ATMOSPHERE AND OF ORDINARY MATERIALS.
Geitel, Phys. Zeit. 2, p. 116, 1900.
C. T. R. Wilson, Proc. Camb. Phil. Soc. 11, p. 32, 1900. Proc. Roy. Soc. 68, p. 151, 1901.
Elster and Geitel, Phys. Zeit. 2, p. 590, 1901.
J. J. Thomson, Proc. Camb. Phil. Soc. 12, p. 391, 1904.
Wood, Phil. Mag. April, 1905.
Campbell, Nature, p. 511, March 31, 1904. Phil. Mag. April, 1905.
APPENDIX B. RADIO-ACTIVE MINERALS.
An apparent exception has been observed by Danne in the case of certain lead minerals which occur under peculiar conditions at d’Issy-l’Évêque, France. See p. 465.