Abstract: This invention relates to apparatus for adding mercury ions to a sample fluid within a flow-through sensor system comprising housing means in fluid connection with a main sample stream conduit via a semi-permeable part (2.11), a first electrode (2.8) located within the housing means preferably designed so that it would be in electrical contact with only the mercury when the mercury is located within the housing means, and a second electrode (2.12) located ideally within the main sample stream conduit, the apparatus being arranged such that when mercury is located within housing means and an electrical current is passed between the first and second electrodes, mercury ions are formed in the housing means which then are able to migrate from the housing means via the semi-permeable part into the main sample stream conduit.

Abstract: An electrochemical cell for use in the detection and measurement of water soluble gases includes a vessel having a first chamber adapted to receive and contain said gas and having located therein a working electrode and a second chamber adapted to contain an electrolyte and having located therein a reference electrode arranged to be in contact with said electrolyte. A counter electrode is located in either the first or second chamber. The working electrode consists of an absorbent material communicating between said first and second chambers, which is adapted to be in contact with said electrolyte and has an electro-active substrate deposited on at least a portion of the surface of that part of the material located in the first chamber.

Abstract: Difficulties occur in finding an electrode which responds reliably to the concentration of some ions.The concentration of a required ion in an electrolyte is measured by measuring the potential between first and second electrodes when the electrolyte is passed from the first electrode to the second electrode through a material which changes the concentration of another ion by an amount which depends on the concentration of the required ion. The first and second electrodes are reliable electrodes for measuring the concentration of the other ion.

Abstract: An electrochemical measuring system is used to determine the proportion of water in ethanol, or of moisture in carbon powder, and consists of a Pb/PbO.sub.2 /PbSO.sub.4 electrode and a Pt/PtO.sub.2 electrode in the ethanol or powder, with a high impedance voltmeter connecting the electrodes.

Abstract: Equipment for measuring the concentration of certain ions, particularly hydrogen ions, is disclosed. The ion sensitive electrodes used in this equipment are far more stable than those previously available. Many of the electrodes described use palladium hydride as the ion sensitive electrode and the electrode is stabilized by monitoring the hydrogen concentration in the palladium and replenishing automatically when necessary.

Abstract: Equipment for measuring the concentration of certain ions, particularly hydrogen ions, is disclosed. The ion sensitive electrodes used in this equipment are far more stable than those previously available. Many of the electrodes described use palladium hydride as the ion sensitive electrode and the electrode is stabilized by monitoring the hydrogen concentration in the palladium and replenishing automatically when necessary.

Abstract: Ion-sensitive electrodes are described for determining the concentration of cations of a predetermined type in electrolytes. In one such electrode a material with a high ionic mobility such as a .beta. alumina may be used to protect material, such as a mercury amalgam, which allows interactions requiring the supply of electrons and the cations to take place internally, both materials containing cations of the predetermined type.

Abstract: An oxygen sensor is described which includes an electrochemical cell having a gas diffusion electrode which includes a porous metal layer and another layer substantially non-porous to the electrolyte but porous to oxygen, interposed between the porous metal layer and the environment of the sensor as the cathode or working electrode, a salt electrolyte capable of being molten at the temperature of operation of the sensor, a counter electrode as anode, a reference electrode, means for maintaining the working electrode at a constant potential with reference to the reference electrode, and means for determining the current flowing in the cell due to the reduction of oxygen present in the environment of the cell at the gas diffusion electrode and characteristic of the amount of oxygen present, the oxygen sensor including a noble metal and noble metal/noble metal oxide electrode as the counter electrode and the reference electrode respectively. Platinum is the preferred noble metal.

Abstract: An ion-sensitive electrode for measuring the concentration of a predetermined ion in a liquid is described which employs a metal hydride, such as palladium hydride, or a metal-alloy hydride in proximity with, or in contact with, a mixture of an acid and the salt of the acid with the predetermined ion. The hydride may be precharged with hydrogen or may be charged in situ.