249.  Rutherford and Soddy, Phil. Mag. April, 1903.

250.  Curie and Debierne, C. R. 133, p. 931, 1901.

251.  Rutherford and Soddy, Phil. Mag. Nov. 1902.

252.  Ramsay and Soddy, Proc. Roy. Soc. 72, p. 204, 1903.

253.  Rutherford and Miss Brooks, Trans. Roy. Soc. Canada 1901, Chem. News 1902.

254.  Loschmidt, Sitzungsber. d. Wien. Akad. 61, II. p. 367, 1871.

255.  See Stefan, Sitzungsber. d. Wien. Akad. 63, II. p. 82, 1871.

256.  P. Curie and Danne, C. R. 136, p. 1314, 1903.

257.  Bumstead and Wheeler, Amer. Jour. Science, Feb. 1904.

258.  Makower, Phil. Mag. Jan. 1905.