PEARLESCENT STRUCTURES 593 The extent of pearlescence in the aqueous concentrates was deter- mined by the particular polyoxyethylene fatty ether and fatty alcohol present. Only polyoxyethylene fatty ethers that were either water- soluble or dispersible gave pearlescent concentrates. Myristyl and cetyl alcohols generally were more effective in producing pearlescent structures than lauryl or stearyl alcohols. Fatty acids were relatively ineffective except for one outstanding combination. Other factors that affected the pearlescence were the concentration of the complex and the ratios of the components. When the temperature of the samples was raised, the pearlescence disappeared. The loss of pearlescence occurred over a temperature range rather than at a specific temperature and this, in conjunction with the peadescent properties of the systems, suggested that the complexes have a liquid-crystalline structure. Not all of the aqueous concentrates retained their pearlescence after addition of the liquefied gas propellants. This effect varied with the type of propellant that was used. The loss of pearlescence probably was due to destruction of the peadescent structure when the propellant was emulsified. (Received October 4, 1968) (1) (2) (3) (4) (5) (6) (7) (8) (•) (10) REFERENCES Sanders, P. A., Complex formation in aerosol emulsions and foams, II. Nonionic surfactants (polyoxyethylene fatty ethers) and polar compounds, Soap Chern. Specialties, 43, 68, 70 (1967). Epstein, M. B., Wilson, A., Jakob, C. W., Conroy, L. E., and Ross, J., Fihn drainage transition temperatures and phase relations in the system sodium lauryl sulfate, lauryl alcohol and water, J. Phys. Chem., 58, 860 (1954). Goddard, E. D., and Kung, H. C., Interaction between ionized surfactants and long- chain polar compounds, Chem. Specialties Mfrs. Assoc., Proc. 52nd Ann. Meeting (December 1965). Cosmetic Bulletin--"Brij" Surfactants (Polyoxyethylene Fatty Ethers), Atlas Chemical Industries, Inc., November 1961. The Atlas HLB System, 4th Printing, Atlas Chemical Industries, Inc. Rosevear, F. B., Liquid crystals: the mesomorphic phases of surfactant compositions, J. Soc. Cosmetic Chemists, 19, 581 (1968). Technical Bulletin--Spectratherm Liquid Crystals, Westinghouse Electric Corp., Insulating Materials Division. Kolp, D. G., and Lutton, E. S., The polymorphism of n-hexadecanol and n-octadecanol, J. Am. Chem. Soc., 73, 5593 (1951). Atkins, F., Pearliness in creams, Perfumery Essent. Oil Record, 25, 332 (November, 1934). Schwartz, A.M., Perry, J. W., and Berch, J., Surface Active Agents and Detergents, Vol. II, Interscience Publishers, Inc., New York, 1958, p. 450.