[151]. Rutherford, Nature, March 2, 1905. J. J. Thomson, Nature, March 9, 1905.
[152]. Crookes, Proc. Roy. Soc. 81, p. 405, 1903.
[153]. Elster and Geitel, Phys. Zeit. No. 15, p. 437, 1903.
[154]. Glew, Arch. Röntgen Ray, June 1904.
[155]. Becquerel, C. R. 137, Oct. 27, 1903.
[156]. Tommasina, C. R. 137, Nov. 9, 1903.
[157]. An interesting side-light is thrown on this question by the experiments described in [Appendix A] of this book.
[158]. Rutherford and Miss Brooks, Phil. Mag. July 1902.
[159]. 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.
[160]. Rutherford, Phil. Mag. Jan. 1899.