9.  Rutherford, Phil. Mag. Jan. 1899.

10.  Ibid.

11.  Le Bon, C. R. 130, p. 891, 1900.

12.  Lenard, Annal. d. Phys. 1, p. 498; 3, p. 298, 1900.

13.  Schmidt, Annal. d. Phys. 65, p. 141, 1898.

14.  Mme Curie, C. R. 126, p. 1101, 1898.

15.  Owens, Phil. Mag. Oct. 1899.