Abstract: An assembly for insertion in a bath of molten material to form therewith an electrochemical cell for determining the concentration of a constituent of the bath. The assembly is of the type including a body structure of refractory material from which protrudes a first electrically conductive element providing means for establishing an electrical connection with the bath and a reference electrode structure separated from the bath by means of a rigid electrolyte material. Reference electrode structures of this general type may be comprised of a closed end tube of electrolyte material or a tube of electrically non-conductive refractory material having a pellet of electrolyte material closing the immersion end thereof to separate the material of the bath from the means establishing a reference potential.

Abstract: In the measurement of ion concentration, a selected base is added to the sample liquid which reduces the hydrogen ion content without producing other cations of a size to which the measuring electrode is sensitive. Bases having a high molecular weight and a dissociation constant, particularly secondary and tertiary amines are suitable for us. The system includes an absorber which mixes sample liquid with gaseous base, means for pressurizing the reference electrode, and an analyzer cell which prevents contamination of the measuring electrode with reference fluid leaking from the reference electrode. A separate reservoir mixes known concentration solutions for calibration purposes. The concentration readout meter of the system includes an auxiliary dial for ease of calibration.