112 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS By applying a layer of oil onto the stratum corneum, the rate of water evaporation from the surface of the skin may be reduced. This moisture, which normally would have been lost, is then deflected back into and increases the moisture content of the stratum comeurn, resulting in a softer skin. In an effort to study the effect of lotions on the water content of the ski% Powers and Fox (11) developed a method, using small desiccators, whereby the rate of moisture loss from the skin could be measured. The desiccator and assembly are shown in Figs. 2 and 3. In this test, the desiccators containing silica gel* are placed on the inner portion of the forearm and held in place by a strip of elastic pajama belting fastened with a bandage clip (see [Pig. 4). Using this test method, it was shown that water-insoluble oily materials definitely retard the percentage of moisture loss from the skin and that certain emulsifiers and humectants may actually accelerate this moisture loss. Data obtained with the ingredients tested are shown in Table 1. Further studies have revealed that the accuracy of the method may be improved by "calibrating" each subject. When the subject is quiescent, * "Tell-Tale" silica gel, 6-16 Mesh, Davison Chemical Co. Figure 4.--The desiccators in position on the inner surface of the forearm.

EFFECT OF COSMETIC EMULSIONS ON STRATUM CORNEUM TABLE 1--MoisTURE Loss FROM THE INNER SURFACE OF THE FOREARM, AFTER THE APPLICATION OF SELECTED COSMETIC RAW MATERIALS (11) 113 Test Material Average Moisture Loss in rag. for 2-Hour Test No. of Average Effect Test Deter- on Moisture Material Control minations Loss Petrolatum, U.S.P. 7.80 14.92 8 Lanolin, anhydrous 9.12 13.39 5 Mineral oil, light tech. 7.94 11.00 4 Lanolin alcohols (25% sol. in mineral oil) 7.46 10.40 3 Isopropyl palmirate 14.65 20.45 3 Silicone oil 7.94 10.72 5 Squalene 9.04 11.70 3 Glyceryl trioleate 8.72 11.30 5 Dewaxed lanolin oil 9.80 12.50 5 Sorbitan sesquioleate 14.50 17.40 3 Polyoxyethylene glycol 200 mono61eate 15.75 15.62 5 Polyoxyethylene glycol 600 mono61eate 12.14 12.12 3 Glyceryl mono61eate (90% mono ester content) 9.70 9.73 4 Safflower Monoglyceride (40% mono ester content) 15.95 16.32 4 Oleyl sarcosine 10.68 10.95 5 Polyoxyethylene glycol 400 mono stearate 12.10 11.60 3 Polyoxyethylene sorbitan mono laurate 12.04 11.48 4 Diethylene glycol mono61eate 11.19 10.28 5 Polyoxyethylene sorbitan mono61eate 12.91 11.26 4 Polyoxyethylene oleyl ether (15-20 Eto) 14.42 11.98 3 Polyoxyethylene oleyl ether (5-10 Eto) 17.75 14.15 5 Propylene glycol, anhydrous 11.55 8.56 5 Glycerine, anhydrous 12.55 8.83 5 48% reduction 32% reduction 28% reduction 28% reduction 28% reduction 26% reduction 23% reduction 23% reduction 22% reduction 17% reduction Nil Nil Nil Nil Nil Nil 5% increase 9% increase 13% increase 22% increase 25% increase 25% increase 43% increase similar moisture loss readings are obtained from the adjacent test sites. However, when the subject is moving about, the moisture loss in one site. may differ from the adjacent site. This difference is probably due to the varying number ofeccrine glands at the different test sites. It is advisable, therefore, to use at least ten control readings for each subject and the results averaged. From these data one can calculate more accurately the percentage difference in moisture loss of the adjacent sites. Calibrating TABLE 2--AVERAGE MOISTURE Loss FROM ADJACENT SITES OF THE INNER PORTION OF TI-IE FOREARM Number of Average Moisture Loss, mg.* Subject Readings Upper Arm Lower Arm Do, %t CK 17 11.0 12.9 18 GB 10 22.5 28.0 25 CF 20 16.6 19.4 17 FM 17 13.3 16.8 26 LF 10 11.0 12.9 17 * Moisture loss is the milligrams of water vapor picked up by the desiccator in a two hour period. •' Dc is the percentage difference of the lower reading compared to the upper reading. L--U D,- X 100 U