1. Barson, N., and Beyer, G. H., Chem. Eng. Progress,49, 243–252 (1953).
2. Brice, B. A., Swain, M. L., Herb, S. F., Nichols, P. L. Jr., and Riemenschneider, R. W., J. Am. Oil Chemists' Soc.,29, 279–287 (1952).
3. Freeman, S. E., U.S. 2,278,309 (1942).
4. Gloyer, S. W., Ind. Eng. Chem.,40, 228–239 (1948).
5. Goebel, C. G., U.S. 2,482,761 (1949).