ANALYSIS OF SUNSCREENS 345 REFERENCES (1) Bruhn, Wolfgang, Solar radiation sunburn and sunscreen,s, Dragoco Rep., 1969• pp. 6, 29. (2) Luckiesh, M., Applications o[ Germicidal, Erythemal and In[fared Energy, D. Van Nostrand Co., New York, 1946, p. 71, 103. (3) Kreps, S. I., The structure, function and formulation of topical sunscreens. I. Theoreti- cal considerations, J. Soc. Cosmet. Chem., 14, 626 (1963). (4) Luckiesh, M., and Holladay, L. L., Fundamental units and terms for biologically effective radiation, J. opt. Soc. Amer. (1933). (5) Handbook o[ Chemistry and Physics, Transparency to Optical Density Conversion Table, The Chemical Rubber Co., Ohio, 1968-9, p. E-251. (6) Kreps, S. I., Spectrophotometric evaluation of sunscreens, Proc. Sci. Sect. Toilet Goods Ass, 23, 13, (1955).

J. Soc. Cosmet. Chem., 23, 347-358 (May 23, 1972) In Vitro and in Vivo Evaluation of Cooling Effect of Cold Creams M. J. SCHNEIDER, B.S., and W. A. RITSCHEL, Ph.D.* Presented December 13, 1971, New York City Synopsis--Sixteen different ointments were evaluated in vitro and in vivo (involving the use of human skin for their COOLING EFFECT using a wet-dry bulb thermometer in vitro and a telethermometer in vivo. Cooling rates were determined. Suggestion is made for changing the composition of the COLD CREAM USP XVIII. INTRODUCTION Cold creams are not only used by the general public as cleansing creams, but they also have value in the treatment of general skin dryness and various pathological skin diseases, notably ichthyosis (1, 2). The use and action of cold creams depend, to a significant degree, on the evapora- tion of water from these preparations. The cleansing action of cold creams is based on solvent and emulsifica- tion processes. Evaporation of water from an O/W cold cream results in phase inversion to W/O. Now the external phase, the oil serves as a solvent for oil-soluble grime. A W/O cold cream cleanses by dissolving the oil-soluble grime in oil, and emulsifying the water-soluble grime in the water (3). Emollient action is the basis for the use of cold creams in dry skin conditions. In its simplest form, an emollient is any substance which alleviates skin dryness. Cold creams combine the emollient effects of water and oil--the water hydrates the skin, and the oil reduces water * College of Pharmacy, University of Cincinnati, Cincinnati, Ohio 45221. 347