1. Hickman, K. C. D., Ind. Eng. Chem.,29, 968–75, 1107–11 (1937).
2. Burch, C. R. and Van Dijk, W. J. D., J. Soc. Chem. Ind.58, 39–42 (1939).
3. Fawcett, E. W. M., Ibid.,58, 50–56 (1939).
4. Burrows, G., Ibid.,58, 50–56 (1939).
5. Jewell, W., Mead, T. H., and Phipps, J. W. Ibid.,58, 56–64 (1939).