Rutherford and McClung, Phil. Trans. A. p. 25, 1901.

Meyer and Schweidler, Wien Ber. 113, July, 1904.

Rutherford and Grier, Phil. Mag. Sept. 1902.

Becquerel, C. R. 129, p. 912, 1899.

Bary, C. R. 130, p. 776, 1900.

Kunz and Baskerville, Amer. Journ. Science XVI. p. 335, 1903.

See Nature, p. 523, March 31, 1904.

Crookes, Proc. Roy. Soc. 74, p. 47, 1904.

Kunz and Baskerville, Science XVIII, p. 769, Dec. 18, 1903.

Beilby in a recent communication to the Royal Society (Feb. 9 and 23, 1905) has examined in some detail the production of phosphorescence by the β and γ rays of radium and has put forward a theory to account for the different actions observed.

Huggins, Proc. Roy. Soc. 72, pp. 196 and 409, 1903.

The spark spectrum of the radium bromide showed the H and K lines of calcium and also faintly some of the strong lines of barium. The characteristic lines of radium of wave-lengths 3814·59, 3649·7, 4340·6 and 2708·6, as shown by Demarçay and others are clearly shown in the figure. The strong line of wave-length about 2814 is due to radium.

Giesel, Ber. d. D. Chem. Ges. 37, p. 1696, 1904.

Hartmann, Phys. Zeit. 5, No. 18, p. 570, 1904.