Cutaneous Reaction

The hydrogen ion concentration of the skin has been the subject of a number of studies in recent years. On the basis of regional and pathologic variations in the acidity of the cutaneous surface, certain hypotheses concerning the physiologic significance of these have been developed, and attempts to treat certain dermatoses by changing the surface acidity have been made. In the present study, in which a simple and rather different method has been used, we have attempted (1) to obtain further data concerning the variation in the hydrogen ion concentration of the surface of the skin, (2) to determine accurately the effect of the skin on theph of acid and alkaline solutions coming in contact with it, (3) to determine the threshold of irritability of normal and scarified skin, so far as the hydrogen ion concentration of the contact substance is concerned, and (4) to check the clinical