178 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS the results of Figure 2. In the remaining two instances the intensity would increase while r remained constant as required by the experimental results. Only in the latter instance however, would the relative humidity dependencies of the elastic and viscoelastic intensities differ, as suggested by the results shown in Figures 2 and 3. Thus, the results suggest that viscoelastic "domains" occur in skin when sufficient water is present to insure that the protein fibers are surrounded by a mucopolysaccha- ride-water gel. As water is removed the gel dissappears and hence, the number of viscoelastic "domains" are decreased. In conclusion, the results suggest that the viscoelastic response of skin at low-strain results from shearing of the mucopolysaccharide-water gel. The shearing force results from the movement of elastin fibers relative to the gel and is confined to hydrated "domains" whose number decreases with relative humidity. Outside of these "domains" the low-strain mechanical properties of skin are governed by elastin alone. REFERENCES (1) G. L. Wilkes, I. A. Brown and R. H. Wildnauer, The biomechanical properties of skin, in CRoe Critical Reviews in Bioengineering (CRC Press, Cleveland, 1973), pp 453-495. (2) R. D. B. Fraser and T. P. MacRae, Molecular structure and mechanical properties of keratins, in Society for Experimental Biology Symposia XXXIV, The Mechanical Properties of Biological Materials, J. F. V. Vincent andJ. D. Curry, Ed. (London, 1980), pp 211-246. (3) J. C. W. Chien, Solid-state characterization of the structure and property of collagen, J. Macromol. Sci-Revs. Macromol. Chem. C12, 1-80 (1975). (4) A. Berg, Z. Eckmayer and S. Smith, Elastin, Cosmetics & Toiletties, 94, 23-38 (1979). (5) T. C. Laurent, Structure of Hyaluronic Acid, in Chemistry and Molecular Biology of the Intracellular Matrix, E. A. Balazs, Ed. (Academic Press, New York, 1970), pp 703-732. (6) L. Roden, Structure and metabolism of the proteoglycans of chondroitin sulfates and keratin sulfate, Ibid, pp 797-821. (7) J. Diamant, A. Keller, E. Baer, M. Litt and R. G. C. Arridge, Collagen: Ultrastructure and its relation to mechanical properties as a function of aging, Proc. R. Soc. Lond. B., 180, 293-315 (1972). (8) Y. Lanir, A structural theory for the homogeneous biaxial stress-strain relationship in flat collagenous tissues,J. Biomech., 12, 423-436 (1979). (9) R. M. Kenedi, T. Gibson, C. H. Daly and M. Abrahams, Biomechanical characteristics of human skin and costal cartilage, Fed. Proc., 25, 1086-1087 (1966). (10) Y. Lanir and Y. C. Fung, Two-dimensional mechanical properties of rabbit skin. II. Experimental results,J. Biomed., 7, 171-182 (1974). (11) J. B. Finlay, Thixotropy in human skin,J. Biomech., 11,333-342 (1978). (12) R. Potts and M. M. Breuer, The mechanical spectrum of skin. I. The experimental technique and measurement at room temperature,J. Soc. Cos. Chem., 32, 339-353 (1981). (13) J. D. Ferry, The Viscoelastic Properties of Polymers, (J. Wiley & Sons, New York, 1980). (14) D. A. Gibbs, E. D. Merrill and K. A. Smith, Rheology of Hyaluronic Acid, Biopolymers, 6, 777-791 (1968). (15) C.J. Hooley, N. G. McCrum and R. E. Cohen, The viscoelastic deformation of tendon, J. Biomech., 15,521-528 (1980). (16) R. Potts and M. M. Breuer, unpublished results.

j. Soc. Cosmet. Chem., 33, 179-191 (July, 1982) Statistical evaluation of vehicle effect on anti-perspirant activity with a limited number of subjects GEORGE E. OSBORNE and JOAN M. LAUSIER, Dept. of Pharmacy, WILLIAM D. LAWING, Dept. of Computer Sciences and Experimental Statistics, University of Rhode Island, Kingston, RI 02881,' MELANIE SMITH, Chesebrough-Pond's, Inc., Trumbull, CT 06611. Received November, 1979. Synopsis The effect of formulation factors (e.g., vehicle) on the efficacy of the antiperspirant agent, aluminum chlorhydrate, was studied. Aluminum chlorhydrate was solubilized in a cream base, an aqueous lotion, and a hydroalcoholic base, and was suspended in a solid stick. Aluminum chlorhydroxy allantoinate was incorporated into all vehicles for its therapeutic and cosmetic properties. A statistically useful experimental design to evaluate antiperspirant efficacy data with a limited number of subjects was developed. Four vehicles containing aluminum chlorhydrate were compared for efficacy by a well-recognized gravimetric procedure during a normal work day in each subject's normal work environment. A pretest sweat collection was used as a blocking factor in designing the 4 x 4, split plot, Latin Square. Post-test sweat collection data were evaluated statistically using the geometric mean of treatment results. All ratio treatment means were converted to percent sweat reduction to determine antiperspirant efficiency. Statistical analysis indicated that the side treated may be selected randomly without compromising the results. The carrier vehicle does not affect antiperspirant efficacy. However, efficacy differences were observed as a function of solution versus suspension. Treatment response in terms of percent sweat reduction was: aqueous lotion, 38.0% hydroalcoholic solution, 32.4% cream base, 31.8%, and solid stick, -6.2%. INTRODUCTION Most of the articles in the cosmetic literature are concerned with the efficacy of the antiperspirant agent or the methods of testing antiperspirant effectiveness (1-4). Studies of topically applied drugs have shown that drug efficiency is dependent on the carrier vehicle in which the drug is placed (5). Kligman (6) tested dimethyl sulfoxide (DMSO) as a carrier vehicle for a variety of topical drugs and observed that certain concentrations of DMSO potentiated the antiperspirant effect of strong aluminum chloride solutions. 179