326 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS range. No extensive selection work has been done in this field. (3) Detergents Atlas detergent materials fall into the HLB range of 13-15. This range is in accord with recent the- ories of detergency that solubilizing of the soil is a part of the action since 13-15 is above the usual O/W emulsifier range and is close to solubilizers. (4) Solubilizers Solubilizing requires the highest HLB (for common uses) at 15-18. For this purpose, single high HLB agents are frequently used. Early work has indicated that the HLB can be too high for efficient solu- bilizing. The effective range ap- pears to be narrow even for different oils. No thorough study of solubil- izing rs. HLB has been undertaken. SUMMARY We have described a system for the choice of emulsifiers based on their hydrophile-lipophile balance/ The HLB system, though it does not indicate the over-all efficiency of the emulsifier, does tell "what it will do"--that is, wha't kind of an emulsion or product to expect. By so doing, it enables us to compare various chemical types of emulsifiers at their optimum balance. Esti- mated HLB values for various types of emulsifiers and fats and oils were presented as well as a method for their determination. Use of the method was illustrated by choosing an emulsifier combina- tion for a typical cosmetic cream. The HLB system appears to be suit- able for all types of problems em- ploying surface-active agents. BIBLIOGRAPHY (1) Goodey, J. H., Australian Chem. Inst. y. & Proc., 16 47 (1949). (2) Lambert, J. M., and Busse, W. F., 5 e. Am. Oil Chem. Sot., 26 289-296 (1949), Table 4. (3) McBain, J. W., et al., Chem. Abst., 31. 16777 36 34139 , 5581a 38 11606 42. 4022b. (4) Roberts, C. H. M., 7. _Phys. chem., 36 3102 (1932). (5) Schwartz, Anthony M., and Perry, James W., "Surface Active Agents Their Chemistry and Technology," In- terscience Publishers, New York, 1949, pp. 346-347. (6) Atlas Powder Company, "Surface Ac- tive Agents," Wilmington, Del., 1948. Table facing pages 26 and 27. * Nots: Span, Tween and Arlex are Reg. Trade Marks, Atlas Powder Company.

COSMETIC FUNCTIONS OF SYNTHETIC DETERGENTS* By ANTHONY M. SCHWAItTZ, Ph.D. Harris Research Laboratories, I'?ashington zz, D.C. QVlTE REGULARLY in the his- tory of chemical technology there have become available radically new materials which stimulate and facili- tate rapid advancement in widely divergent fields. The introduction of such materials is usually followed by a period of intensive develop- ment during which specialists in- vestigate them and attempt to utilize their novel characteristics to fullest advantage. For some time, we have been in such a stage with regard to the synthetic surface- active agents. Cosmetic technolo- gists have not lagged behind the leaders in taking advantage of these new substances. The basic purpose of this paper is to indicate some of the interesting specific characteris- tics of surface-active agents, and to consider how they might be utilized to an even fuller potential. The more general physical and chemical properties of the surface-active agents have been amply surveyed and are by now quite familiar. A brief review of the more important points will,'however, serve to orient the subsequent discussion. * Presented at the May 20, 1949, Meet- ing, New York City, 327 With respect to chemical struc- ture the surface-active agents are characterized by having a highly unsymmetrical molecule, one por- tion of which is 2•olar and hydro- Milic, with high residual valency. The other portion of the molecule is non-f•olar and hydrophobic. pending on the relative influence of these two portions the material will be primarily oil-soluble or water- soluble, although many common surface-active agents are soluble in both types of solvent. The oil-sol- uble substances are of considerable technical importance but this dis- cussion will be concerned largely with the water-soluble series. These produ.cts may be classified primarily according to the nature of the drophilic group as shown in Table 1. A second basis for classification is the nature of the hydrophobic group. In cohamercial detergents this group is seldom, if ever, molec- ularly uniform. It usually consists of a mixture of isomers or homo- logues belonging to the same series. The more common series of hydro- phobic groups are: (1) The straight chain aliphatic hydrocarbon groups of 8 to 18 carbon atoms, derived di-