The article by David E. Goldman explores the electrical properties of membranes, focusing on potential, impedance, and rectification. Goldman reviews the historical development of electrical measurements on biological cells and tissues, highlighting the importance of steady current and alternating current (a.c.) measurements in understanding ion motion and conductance. He discusses the use of a.c. measurements to determine capacitance and the equivalent circuit model of the cell membrane as a parallel resistance-capacitance combination. Goldman introduces the concept of rectification, where the conductance changes with the direction of current flow, observed in various biological systems such as Valonia, the squid giant axon, and frog muscle. He also discusses the membrane hypothesis of Bernstein, which suggests that the permeability of the cell membrane increases during activity, leading to changes in conductance. The article details the experimental methods used to study the electrical properties of membranes, including the preparation of artificial membranes from protein, collodion, and phospholipid. The measuring equipment and procedures are described in detail, emphasizing the importance of controlling environmental solutions and maintaining stable conditions. The results section presents the findings from impedance and conductance measurements on various membranes, including protein membranes, collodion membranes, and plant cuticles. Goldman notes that the membranes behave like parallel resistance-capacity combinations, with capacitances having a phase angle less than 90° and conductances proportional to those of the environmental solutions. He also discusses the rectification properties, which vary with the membrane potential and current. The theoretical analysis section provides a mathematical framework for understanding the current-voltage relationship in membranes, considering the influence of dielectric constants, ion mobilities, and activity coefficients. Goldman compares the predictions of different theoretical models, such as the Planck equation and the constant field assumption, with experimental data. Finally, the discussion section reflects on the implications of the findings for biological membranes, suggesting that the subthreshold electrical properties may be interpretable in terms of physical rather than metabolic processes. Goldman concludes by emphasizing the need for further research to understand the complex behavior of biological membranes and the potential for using synthetic materials to study membrane properties.The article by David E. Goldman explores the electrical properties of membranes, focusing on potential, impedance, and rectification. Goldman reviews the historical development of electrical measurements on biological cells and tissues, highlighting the importance of steady current and alternating current (a.c.) measurements in understanding ion motion and conductance. He discusses the use of a.c. measurements to determine capacitance and the equivalent circuit model of the cell membrane as a parallel resistance-capacitance combination. Goldman introduces the concept of rectification, where the conductance changes with the direction of current flow, observed in various biological systems such as Valonia, the squid giant axon, and frog muscle. He also discusses the membrane hypothesis of Bernstein, which suggests that the permeability of the cell membrane increases during activity, leading to changes in conductance. The article details the experimental methods used to study the electrical properties of membranes, including the preparation of artificial membranes from protein, collodion, and phospholipid. The measuring equipment and procedures are described in detail, emphasizing the importance of controlling environmental solutions and maintaining stable conditions. The results section presents the findings from impedance and conductance measurements on various membranes, including protein membranes, collodion membranes, and plant cuticles. Goldman notes that the membranes behave like parallel resistance-capacity combinations, with capacitances having a phase angle less than 90° and conductances proportional to those of the environmental solutions. He also discusses the rectification properties, which vary with the membrane potential and current. The theoretical analysis section provides a mathematical framework for understanding the current-voltage relationship in membranes, considering the influence of dielectric constants, ion mobilities, and activity coefficients. Goldman compares the predictions of different theoretical models, such as the Planck equation and the constant field assumption, with experimental data. Finally, the discussion section reflects on the implications of the findings for biological membranes, suggesting that the subthreshold electrical properties may be interpretable in terms of physical rather than metabolic processes. Goldman concludes by emphasizing the need for further research to understand the complex behavior of biological membranes and the potential for using synthetic materials to study membrane properties.