50
Strutt, Phil. Mag. June, 1903.
51
Elster and Geitel, Phys. Zeit. 4, No. 19, p. 522, 1903. Chem. News, July 17, p. 30, 1903.
CHAPTER XIV. RADIO-ACTIVITY OF THE ATMOSPHERE AND OF ORDINARY MATERIALS.
1
Geitel, Phys. Zeit. 2, p. 116, 1900.
2
C. T. R. Wilson, Proc. Camb. Phil. Soc. 11, p. 32, 1900. Proc. Roy. Soc. 68, p. 151, 1901.
3
Elster and Geitel, Phys. Zeit. 2, p. 590, 1901.