Data are given on the density of charge convected by the laminar flow in capillary tubes of cyclohexane containing different additives. We make special note of the experimental results which correspond to a fully developed charge density profile in the output section of the tube, when solutions are either very resistive ( greater than 3 multiplied by 10**1**1 OMEGA m), or rather conductive ( less than 10**1**0 OMEGA m). The true zeta potential was 17 mv for cyclohexane and TiAP and 75 mv for cyclohexane and Aerosol OT. These values were found independent of the solution conductivity.