pH Measurements with a Glass Electrode Withstanding 1500 kg/cm2 Hydrostatic Pressure

Abstract

A glass electrode can be made to withstand high hydrostatic pressure, up to 1500 kg/cm², by separating the inside fluid from the outside one with a layer of silicone oil acting as a liquid piston, enabling the inside and outside pressure to compensate continuously. Such a glass electrode, with two Ag–AgCl electrodes, maintains its hydrogen electrode function at high pressure. pH changes resulting from dissociation constant shifts caused by pressure in acid and buffer solutions have been measured in good agreement with theoretical expected values for HCl, acetic acid, carbonic acid, and acetate buffer. No agreement was found for bicarbonate buffer. Phosphate buffer and sea water have also been tested. An adapted version of the cell‐assembly is planned to equip the French bathyscaphe for deep‐sea investigations.