360 . JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS be physiologically identical with similar conditions resulting from exposure to the uncontrolled environment. We note, however, that at our level of observa- tion, soap-induced dryness is not noticeably different from that observed on first examination of untreated subjects during cold, dry weather. Subjects who display signs of environmentally induced dryness and are aware of this as a seasonal cosmetic problem, can be made to develop the signs of dryness at any time of the year in this test, but they respond less readily and less intensely in warm moist weather. We have not measured this seasonal effect by direct ex- periment nor can we comment on the possibility of a corresponding seasonal change in responsiveness to cosmetic treatment and we must, therefore, rec- ommend that direct comparisons of efficacy be made simultaneously. Definitions of the terms "dry skin" and "moisturizer" have been proposed to emphasize testing parameters and foster uniformity in research on moisturi- zation. ACKNOWLEDGMENTS The authors wish to thank Avon Products, Inc., for supporting this work and authoriz!ng its publication. We are also indebted to Dr. Harry Smith, Jr., Department of Biostatis- tics, Mount Sinai School of Medicine, New York, New York for the design of the statistical experiments reported here. The contribution of Anthony Leardi and John Sutherland, who were responsible for writing the Fortran computer program used in the experiments discussed in this paper, and the excellent technical assistance of Douglas Clark and Mary Ann Perini are gratefully acknowledged. REFERENCES (1) D. H. Powers and C. Fox, The effect of cosmetic emulsions on the stratum corncure, J. Soc. Cosmet. Chem., 10, 109-16 (1959). (2) F. A. J. Thiele and K. Schulter, A new micro method for measuring the water- balance of human skin. Salt crystal method, J. Invest. Dermatol., 39, 95-103 (1962). (3) E. W. Rosenberg, H. Blank, and S. Resnick, Sweating and water loss through the skin, J. Amer. Med. Ass., 179, 809-11 (1962). (4) H. Baker and A.M. Kligman, Measurement of transepidermal water loss by elec- trical hygrmnetry, Arch. Dermatol., 96, 441-52 (1967). (5) D. Spruit, Measurement of water vapor loss from very small areas of forearm skin, J. Invest. Dermatol., 58, 109-13 (1972). (6) M. M. Reiger and D. E. Deem, Skin Moisturizers. I. Methods for measuring water regain, mechanical properties, and transepidermal moisture loss of stratum corneum, J. Soc. Cosmet. Chem., 25, 239-52 (1974). (7) K. Laden and R. Morrow, Torsional measurements on skin, J. Soc. Cosmet. Chem., 21,417-25 (1970). (8) A. C. Park and C. B. Baddiel, Rheology of stratum corneum. Part I. A molecular interpretation of the stress-strain curve, J. Soc. Cosmet. Chem., 23, 3-12 (1972). (9) A. C. Park and C. B. Baddiel, Rheology of stratum corneum. Part II. A physico- chemical investigation of factors influencing the water content of the corncure, J. Soc. Cosmet. Chem., 23, 13-21 (1972).

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