360 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS ß face, water droplets do not tend to spread readily and the surface of the skin cannot be considered as particularly hydrophilic even when •clean? • There is little question that the work being done on combination of surface-active ions with proteins is of considerable importance and sig- nificance to the cosmetic industry. Contributions in this field are ap- pearing at an accelerated rate and while often difficult to follow because of highly mathematical treatments, well deserve the attention of the cosmetic chemist. Another common misconception is that soap is not suitable for formu- lation of hard water shaml:(OOS. There is no question that soap--es- pecially coconut oil soap•has many desirable properties not easily dup- licated by synthetics. Aside from the fact that s. oap produces the con- ventional feel of skin and hair, the lather produced by coconut soaps is excellent. It is copious, viscous, and stable in soft water. It rinses readily in soft water. In hard wa- ter, the volume and viscosity of the lather fall and during the rinsing operation, the dilution of soap with large quantities of water containing calcium and magnesium results in the precipitation of the correspond- ing alkali earth soaps on the hair. The inclusion of water-softening agents in liquid soaps is now widely practiced due to the improved availability of organic sequestering agents which are compatible with potassium and triethanolamine soaps and which do not hy•irolyze on storage in aqueous solutions. Typical of such products is ethyl- enediamine tetraacetic acid. The neutral and alkaline salts form chelate complexes with 'cal- cium and magnesium (13) and thus prevent the precipitation of soap by these ions. It is now possible to manufacture liquid soaps which often do not require refrigeration or filtering and which will not cloud in glass containers. The addition of a few per cent of ethylenediamine tet- raacetate to a soap shampoo will prevent the decrease in lather vol- ume and viscosity in hard water. Foam measurements on dilute solu- tions of soap and sequestrant have been made (13) and these results have also been confirmed for high concentrations of soap. Five per cent solutions of soap containing 0.5 per cent ethylenediamine tetra- acetate show no drop in lather vol- ume or viscosity at 500 ppm. hard- ness as tested in a Waring blendor. This concentration of sequestering agent is also adequate to neutralize such hardness as may be encoun- tered on preliminary dilution and rinsing of the lather. It is not adequate, however, to neutralize the hardness of all the rinse water used, and in all probability these organic sequestrants rinse faster than does the soap, leaving it un- protected. The precipitation of calcium and magnesium soap on the hair during dilution may be prevented by the addition to the soap of a lime-soap dispersant. The function of this material is perhaps more correctly

to retard the development of soap curds. Table 1 compares the trans- mirrance of 0.2 per cent soap solu- tions containing 0.02 per cent of various surface-active agents at 25øC. readings being made five minutes after making up the solu- COCO•AT• XND 0.02• DISPERSXNT I• 200 PPM. CaCO• K cocohate only ................... 66% Non-ionic ether .................... 85% Na lauryl sulfate ................... 70% Coconut fatty amide ............... 81% Non-ionic ester .................... 84% Dodecyl toluene sulfonate ........... 79% Oleic amide sulfonate ............... 84% If these solutions are allowed to stand long enough, they will even- tually all show the same low trans- mittance. One cannot, however, formulate soap and lime soap dis- petsant on the basis of these data alone. The foaming properties of (1) binary mixtures of surface-active agents are not predictable. The (2) adverse effect of soap on alkyl aryl (3) sulfonate foam is well known and (4:) has even been utilized to make non- foaming wetting agents. Lathering (5) experiments using high concentra- (6) tions of soap and alkyl aryl sul- fonate confirm the results obtained (7) at low. concentrations, although, (8) strangely enough, the defoaming effect is not picked up easily in the (9) Waring blendor test. Hand lather- (10) ing experiments also indicate that (11) the fatty amides of the Altosol (12) type enhance lather, at the same (13) time retarding precipitation of the SHAMPOO FORMULATION 361 lime soap. None of these materials has the same effect on the lathering properties of the soap in hard water that organic sequestrants have. A mixture of soap, plus lime-soap dispersant, does not show good lathering properties in hard water unless organic sequestrant is present. Considering the number of years that shampoos have been manu- factured and marketed, no one can complain that conditions in this field are static.. Shampoos today account for over 50 million dollars in sales volume. The cosmetic chemist today must search con- stantly for new possibilities. Fortu- nately, he has an untapped wealth of raw materials still available to draw on. BIB LIOGRAPH¾ Stoves, j. L., y. Soc. Leather Trades Chemists, 32, (8), 254: (1948) Nature, 157, 230 (1948). Putnam, F. W., "Advances in Protein Chemistry," Vol. 4, p. 79 (194:8). Valko, E., Atnn. of N.Y. Atcad. Sci., 4,6, 4:51 (1946). Harris, M., Textile Research y., 18, 669 (1948). Neville and Jeanson, Arm. Dyestuff Reptr., 22, 565 (1933). Steinhardt, Fugitt, and Harris (1942): y. Res. Natl. Bureau Standards, 28, 201 (1942). Steinhardt, and Fugitt, Ibid., 29, 315 (1942). Aickin, R. G., y. Soc. Dyers Colorists, 60, 60 (194{). King, y. Textile Inst., 13, 127 T (1922). Neville, H. A., and Harris, M., Arm. Dye- stuff Reptr., 2't, 312 (1935). Baker, Z., et al., y. •Exper. Med. 74, 621 (1941). Tech. Bull., Alrosept MB (Alrose Chemical Co.). Zussman, H. W., Soap & Sanitary Chem., 24, (2), 57 (1947).