The electrical properties of the inner epidermis of the onion scale

Abstract

The inner epidermis of the onion scale is shown to resemble the dried collodion membrane in being relatively very impermeable for anions in dilute solutions of electrolytes and in retaining this impermeability for an indefinite period. For uni-univalent electrolytes the potential across the membrane tends with increasing conc. to a limit equal to the liquid junction potential (l.j.p.) in the absence of the membrane. For electrolytes containing a bi- or trivalent cation the potential falls with increasing conc. below the value of the l.j.p. and the membrane appears to be more permeable for anions than for cations. Additions of small amts. of bi- or trivalent cations to solutions of KC1 in contact with the membrane has a disproportionately large depressing effect on the potential.