1. Becquerel, J.Phys. Zeits., 1907,8, 932. Becquerel, J.C. R., 1910,151, 859; 1911,152, 183.
2. Bhagavantam, S., and Venkatarayudu, T.Proc. Ind. Acad. Sci., A, 1939,9, 224.
3. BoisbaudranC. R., 1887,106, 452.
4. CoblentzInvestigations, 1908,5, 17, 34.
5. Crookes, W.Chem. News., 1887,55, 251;56, 59. Crookes, W.Nature, 1889,39, 542.