ion. It is necessary to prevent the glass membrane from drying out because the performance is dependent on the existence of a hydrated layer, which forms slowly. See also Potentiometry Ion-selective electrodes ISFET pH electrode Chalcogenide glass Quinhydrone electrode Solid State Electrode References E. P. Nikol'skii, M. M. Schul'tz, et al., Vestn. Leningr. Univ., Ser. Fiz. i Khim., 18, No. 4, 73-186 (1963) (This series of articles summarizes Russian work on the effect of varying the glass composition on electrode properties and chemical stability of a great variety of glasses) External links pH electrode practical/theoretical information Titration with the glass electrode and pH calculation - freeware Electrodes Glass applications