The permeability of human skin to electrolytes

The epidermis is not only a protective covering against mechanical injury, but presumably protects the body also from diffusion inwards of foreign sub-stances or diffusion outwards of normal constituents of the blood. In a previous paper (Whitehouse, Hancock and Haldane, 1932) it was shown that though the epidermis, so that in this respect the epidermis seems to play the part of semi-permeable membrane. The question of the permeability of the epidermis to various substances which are met with in mining and other operations, or are applied with a remedial object, is of much practical interest, and in connection with the treatment of mining accidents from burning, the apparent impermeability of the outer epidermis to colloidal solutions of tannic acid and ionized solution is of special importance. It is presumably the dense stratum lucidum , of the external epidermis that tends to stop diffusion. The present investigation deals with the question whether the skin is entirely impermeable to electrolytes in solution. The choice of suitable substances for the tests was necessarily limited to elements which are either not present in urine or blood, or present in only very small amounts, and which could also be detected and determined very accurately.