1. Gurwitsch, L., and Moore, H., “The Scientific Principles of Petroleum Technology,” p. 485, New York, D. Van Nostrand Co., 1932.
2. Haseman, J. D., “The Alleged Catalytic Action of Fuller’s Earth on Coloring Matter in Oils,” paper presented before Amer. Oil. Chem. Soc., New Orleans, May 5–6, 1924.
3. Nutting, P. G., “The Bleaching Clays,” U. S. Geol. Survey Circular 3, pp. 11, 17, 20 (1933).
4. Kerr, P. F., “Montmorillonite or Smectite as Constituents of Fuller’s Earth and Bentonite,” Jour. Miner. Soc. of Amer., 17, No. 5, 192 (1932).