1. This is summarised in Kayser's “Handbuch der Spektroscopie,” Vols. 5, 7.
2. R. T. Birge, paper before Am. Phys. Soc.: abstr., Phys. Rev., 23, 294 (1924).
3. Cf. Lord Rayleigh and Prof. A. Fowler, Proc. Roy. Soc., 86A, 113 (1912);
4. Lord Rayleigh, ibid., 102A, 453 (1923).
5. E. Freundlich and E. Hochheim, Zeit. f. Phys., 26, 102 (1924).