WATER LOSS OF STRATUM CORNEUM 251 ] o0 m 0o5 m 32O ! y x l0 s (deg -!) Figure 7. Water permeation through stratum comeurn as a function of temperature •. The rate o• water vapor absorption o• human stratum corneum depends on the relative humidity. The equilibrium water content o• extracted and nn- extracted human stratum corneum at humidities below about 80% is essential- ly the same. 3. The rate of water vapor transmission through human stratum corneum in vitro is a linear function of the ambient relative humidity. Th•s rate is markedly decreased by a reduction in temperature. ( Received November 13, 1973 )

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