The polyethylene capillary used for dropping mercury electrodes (D.M.E.) has permitted the study of interfacial tension by a drop time method in highly concentrated solutions. The electrocapillary curves were obtained for the aqueous solutions of KF, NaOH and KCL. The measurements evince that there is a difference between results obtained using glass and polyethylene capaillaries. The difference increases with the concentration of the electrolyte. We attribute that fact to wetting of the polyethylene capillary by mercury.