776 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS physiological factors or by artificial means (cooling, heating, relative humid- ity of the air, drugs, etc.). The intensity of local sweating can be increased in specific limited areas by several locally applied drugs however, this is of significance primarily for experimental work. Topical agents, capable of limiting or temporarily stopping excessive sweating on a given area of the body surface, have found much greater utility in medicine and cosmetics. In addition to the other effects, their applica- tion leads to changes in the microcirculation of water in the skin and can form the etiopathogenetic basis for certain pathological skin conditions, such as miliaria etc. The objective evaluation of the antiperspirant effects of various agents used for this purpose is very difficult and in such studies, several basic physiological facts related to sweating must be considered. On the palms and soles, the regions of so-called psychic sweating, the structural and chemical dissimilarity of the thick horny layer (2), the position of the person under study (3) (4), and the intensity of the psychic or sensory stimulus (5) are significant. In these areas, penetration of externally applied drugs occurs primarily through numerous eccrine sweat ducts of glands which are continuously elaborating sweat. In the extra-palmoplantar regions, the areas of so-called thermal sweating, sweating can be caused by the generalized or local application of drugs, such as pilocarpine, or by general heating. Pharmacological sweating differs from physiological/thermal sweating both in the course and the composition of the expelled perspiration (6). Absorption in these areas occurs primarily via the direct transcorneal path and to a lesser extent via the hair follicles. Absorption via sweat gland ducts does not occur under normal temperature conditions. In the evaluation of experimental data one must realize, however, that even under subthreshold thermal stimulation, psychic sweating may occur in extra-palmoplantar regions in the same way as on the palms and soles (5). The penetration of antiperspirants and also the depth of their action are largely dependent on the degree of hydradon of the surface horny layer which in turn is significantly influenced by the type of vehicle from which the antiperspirant is applied (7) (8) (9). Excessive hydradon, i.e., conditions of occlusion, can by itself limit sweat output through swelling of the terminal portions of the eccrine sweat duct (hidromeiosis) (10) (11) (12). The authors have attempted to overcome the noted difficulties via a rational approach based on current publications. In addition, the authors' experience was utilized which was obtained during earlier work in this field (a combination of the measurement of the actual sweat output with the aid of a quickly responding resistance hygrometer and of a perspiration

COMPARISON OF THE EFFECTIVENESS 777 print test with the aid of a contact indicator). Simultaneous application of these methods yielded a complete picture of the quantity and the dynamics of sweat secretion and of the frequency distribution of active sweat glands. This type of information cannot be obtained simply by employing only one of the two above-mentioned methods. During recent years many authors have dealt with problems associated with the evaluation of topical anti- perspirants [(13) to (25)]. The antiperspirant efficacies of several chemical agents, which are used either in pure form or in combinations for topical antiperspirancy as well as deodorization, are compared in the present study. It includes formaldehyde, aluminum chloride, zinc chloride, hexamethylene tetramine, and sodium hexametaphosphate. MATERIALS AND METHODS The anhidrotic effects of aqueous solutions of the following chemical agents at the indicated concentrations were investigated: Formaldehyde--l% , 5%, 10% aluminum chloride--15% zinc chloride--5% hexamethylene tetramine--20ø//0 sodium hexametaphos- phate--10 •o. For control purposes, distilled water was tested by the same procedure. The exposure to the test agent was either 1, 3, or 10 hours. Measurements were commenced within one hour after the removal of the test material from the volar side of the forearm. METHOD OF APPLICATION Several layers ofWhatman 1 filter paper squares (4 x 4 cm) were moistened with the test solution of the antiperspirant and applied to a previously de- lineated area. The central portion of the moistened squares was then covered with a polypropylene film to an extent of approximately 2 x 2 cm. The purpose of this partial covering with a water-proof film was twofold: to prevent rapid drying of the test solutions and to allow partial evaporation of water vapor formed underneath the occlusive film. The occurrence of anhydrosis due to excessive swelling of the horny layer (hydromeiosis) was thus avoided and the efficacy of this procedure had been verified by pre- liminary experimentation. It was also possible to remoisten the protruding filter paper margins with the solutions of the tested antiperspirants whenever long exposures were required. The final fixation to the skin was carried out with a layer of polyurethane foam sponge and a bandage. Tests were con- ducted on a total of 15 subjects ranging in age from 14 to 16 years. Sweating was elicited by exposing the subjects to heat in a polypropylene tent with the aid of a hot air stream (55 øC). During the measurement, the test subjects