[271]. 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.”
[272]. Rutherford, Phil. Mag. Feb. 1900.
[273]. Rutherford, Phys. Zeit. 3, No. 12, p. 254, 1902. Phil. Mag. Jan. 1903.
[274]. Miss Brooks, Phil. Mag. Sept. 1904.
[275]. Rutherford and Miss Brooks, Phil. Mag. July, 1902.
[276]. Curie and Danne, C. R. 136, p. 364, 1903.
[277]. Mme Curie, Thèse, Paris, 1903, p. 116.
[278]. Debierne, C. R. 138, p. 411, 1904.
[279]. Giesel, Ber. d. D. Chem. Ges. No. 3, p. 775, 1905.
[280]. Miss Brooks, Phil. Mag. Sept. 1904.