COSMETIC KNOWLEDGE THROUGH INSTRUMENTAL TECHNIQUES 137 The sensitivity of the DTA method was shown by its ability to dis- tinguish virgin hair from neutralized waved hair, from no-neutralized waved hair, from reduced hair. Figures 10 and 11 show the DTA curves given by these substances. The differences were not huge, by any means, and were complicated by the fact that even differences in the source of virgin hair were detectable, but the curves did indicate that real differences could be found. OTHER POSSIBLE METHODS There are many other instrumental techniques where increased use in cosmetics research can be foreseen. These range from mere extensions of those discussed, as for example electrochromatography where an electrical dimension has been added to paper chromatography causing the sideways migration of ionic species to be superimposed on their downward movement, to new excursions into the electronic realm of radio and microwave spectros- copy. The new methods of Nuclear Magnetic Resonance and Para- magnetic Resonance appear to have great potential as analytical tools. If research money becomes more plentiful, the cosmetic industry will be able to acquire much greater benefit from the use of the electron microscope, the mass spectrometer, x-ray diffraction, etc. The electron microscope, especially, has proved invaluable in fiber research (7). It also played an important role in demonstrating the effectiveness of stannous fluoride as a protective treatment in preventing acid attack on tooth enamel (8). Finally, we may speculate that the measurement of smells and odors may I I I I I I I I I lOO 200 300 400 SAMPLE TEMPERATURE (øC) Figure 10.--Differential thermal analysis cur:yes of reduced human hair and virgin human hair.

138 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 25 No neut•alixed hai• ..'•-- -- 100 200 300 400 SAMPLE TEMPERATURE (*C) Figure 11.--Differential thermal analysis curves of human hair processed by "no-neutralizer" waving procedure and human hair after reduction and fixative treatment. be achieved by instrumental means. This is a field that interests us a great deal, and we are confident that its application to problems in cos- metic research will eventually be achieved. The potential for such a method would seem to be enormous. The goal is well worth attaining. REFERENCES (1) McDonough, E.G., "The Development of Machineless Permanent Waving," J. Soc. COSMETIC CHEM., 1, 183 (1948). (2) McDonough, E.G., "Mercaptans in Cosmetics," Ibid., 1, 27 (1947). (3) Dimick, K. P., Stitt, F., and Corse, J., "Volatile Flavor of Strawberries. II Application of Gas-Liquid Partition Chromatography," Symposium on Vapor Phase Chromatography, American Chemical Society Meeting, Dallas, Tex., April, 1956. (4) Gohlke, R. S., and McLafferty, F. W., "Use of Vapor-Phase Chromatography in the Identification of Unknown Mixtures," Symposium on Vapor Phase Chromatography, American Chemical Society Meeting, Dallas, Tex., April, 1956. (5) Bernstein, R. B., "Infra-red Spectroscopy and Its Application to Cosmetic Chemistry," J. SOC. COSMETIC CHEM. 3, 265 (1952). (6) Hausdorff, H. H., "Infrared Applications to the Analysis of Cosmetics and Essential Oils," Ibid., 4, 251 (1953). (7) Courchene, W. W., "The Electron Microscope--A Tool for the Study of Hair Fibers," Ibid., 7, 60 (1957). (8) Gray, J. A., Schweitzer, H. C., Broge, R. W., and Rosedear, S. B., "Electron Microscope Studies of Tooth Enamel After Application of Stannous and Sodium Fluorides," Inter- national Association of Dental Research Meeting, St. Louis, March, 1956.