Giesel, Ber. d. D. Chem. Ges. No. 3, p. 775, 1905.

Miss Brooks, Phil. Mag. Sept. 1904.

Rutherford, Phys. Zeit. 3, No. 12, p. 254, 1902.

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.