20 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS number of lanolin acids. Acids constitute approximately 50% of the esters whose hydroxyl number is in the range of 24 to 29. Therefore the fatty acids liberated from lanolin monoesters should have a hydroxyl number twice that of the esters, or a range of 48 to 58. The corrected range of hydroxyl number for our acids is 62 to 88 indicating that a considerable amount of diesters is present in lanolin. Further evidence that the combinations are not random is given by Truter (13) who could not isolate straight chain esters by means of urea in anything but negligible quantities. If random combinations were the rule, at least 12% of such esters should be present. Bertram (1) calculated that diesters constituted 91.5% of the esters of the American, and 31.7% of the esters of the Australian wool fat. The actual separation and identification of individual lanolin esters is an immense task, but great impetus has been given to this type of investiga- tion by new methods and modern equipment. Urea may be used as a com- plexing agent to separate lanolin into straight, branched chain, and cyclic ester groups. In 1952 Tiedt and Truter (18) subjected a fraction oflanolin to an 85-stage systematic fractional crystallization, resulting in the isolation and identification of three cholesterol monoesters of branched chain acids. They also isolated a diester of a hydroxyacid and another hydroxyacid of unknown structure whose molecular weight, 489, is considerably higher than for any hydroxyacid isolated hitherto from lanolin. These findings are consistent with the idea that lanolin esters as formed in nature may be simple or exceedingly complex, and confirms the suspicion that degradation during separation and analysis has added greatly to the difficulties in elucidation of the chemical structure of the unaltered lanolin. COMPOSITION P$. EMULSIFYING PROPERTIES In studying the emulsifying properties of lanolin an interesting applica- tion can be made of the data which has been presented. The ability to form water-in-oil emulsions is the outstanding character- istic oflanolin but a study of the literature for the past 30 years reveals only disagreement as to which fraction endows lanolin with this property. In the recent literature, Maimstrom (19) in 1949 found "no indication that the free, combined or total cholesterol had any effect on the water absorp- tion power of lanolin," and concluded that the water absorption properties were "due to the composition of the mixture." Bertram (1), whose data have been presented here in detail, attributed the emulsifying properties to the high molecular weight diesters of hydroxy- acids. Tie& and Truter (20) carried out an extensive investigation in 1952 and concluded that the esters of lanolin were incapable of forming emulsions by themselves. They attributed the emulsifying power to the free alcohol content and to a minor extent to the free acids. The stability of these

NEWER CONCEPTS OF LANOLIN COMPOSITION 21 emulsions was attributed by them entirely to the free alcohols. These authors found, as have others, that mixtures of the alcohols were better than a pure single alcohol. They also reported that the diols in the alcohol frac- tion were the most active of all. It was mentioned previously that Fieser (8) had isolated a diol from a fraction of lanolin alcohols. This fraction, because of its surface activity is used in the production of emulsifiers. Fieser reported that the diol was tried as a co-emulsifier and found to be more promising than cholesterol. It might be of interest to add some of our own observations on emulsi- fication. If lanolin is modified by reacting its hydroxyl groups the emulsi- fication property disappears. The addition of a surface-active extract of lanolin alcohols to this modified laBolin, and as a control to U.S.P. laBolin, results in marked improvement in water absorption in each case, but the water absorption levels of modified lanolin remain far below those of the U.S.P. lanolin. This indicates that in addition to the free alcohols, hydroxy- esters might play a part in the emulsification properties oflanolin. These hydroxyesters may not be restricted to diesters as stated by Bertram (1), but could include monoesters of hydroxyacids. We find that laBolin fatty acid mixtures free of alcohols and containing 40% of hydroxyacids, emulsify only slightly less water than lanolin U.S.P. Tile addition of these acids to the modified lanolin and to U.S.P. laBolin re- suits in improvement in the former, and slightly decreased water absorption in the latter. It appears that the alcohols are by far the most active emulsifiers of lanolin, the diols perhaps best of all. The hydroxyesters may have emulsi- fying properties but no direct evidence has been obtained, and additional data are required as proof of this activity. The laBolin acids are fair water- in-oil emulsifiers but they are present in U.S.P. lanolin in such small quan- tities that it is doubtful whether they have any significant effect on emul- sification. The chemistry of laBolin has entered a period of enlightenment which promises to unravel many of the mysteries of this complex substance. We already have a new concept of composition which is serving as the basis for the development of more effective products from lanolin and its compon- en t s. BIBLIOGRAPHY (1) Bertram, S. H., •7. Am. Oil Chem. Soc., 26, 454-456 (1949). (2) Weitkamp, A. W., 5 t. Am. Chem. Soc., 67, 447-454 (1945). (3) Drummond, J. C., and Baker, L. C., •e. Soc. Chem. Ind., 48, 232-238 (1929). (4) Lower, E. S., Croda publication "Lanolin," 1951. (5) Hembrough, G. R., Chem. Prod., 175-178 (May 1953). (6) Warth, A. H., "The Chemistry and Technology of Waxes," Reinhold (1947), p. 77. (7) Horn, D. H. S., and Hougen, F. W., Chemistry & Industry, 670 (Aug., 1951). (8) Fieset, Louis F., Harvard University, Personal Communication, 1953. (9) Tiedt, J., and Truter, E. V., 5 t. Chem. Soc., 4628-4630. 1952, (10) Murray, K. E., and Schoenfeld, R., •e. Am. Oil Chem. Soc., 29, 416-420 (1952).