1. Schulman, J. H., and Rideal, E. K., Proc. Roy. Soc., B, 122, 29 (1937). Schulman, J. H., and Stenhagen, E., Proc. Roy. Soc., B, 126, 356 (1938). Schulman, J. H., Trans. Farad. Soc., 23, 1116 (1937). Marsden, J., and Schulman, J. H., Trans. Farad. Soc., 24, 749 (1938). Cockbain, E. G., and Schulman, J. H., Trans. Farad. Soc., 25, 716 (1939).
2. Dodds, Lawson and Campbell, NATURE, 142, 1121 (1938). Dodds, Golberg and Robinson, NATURE, 142, 34 (1938); 141, 247 (1938). Dodds and Lawson, NATURE, 139, 1068 (1937). We are indebted to Prof. Dodds and Dr. Lawson for specimens of these derivatives.