One surface of the immersion capacitance consists of an electrically uninsulated metal tube (C1/2a). A second surface (C1/2b) is in the form of a coating on a further tube suspended inside the first tube so that the measurement medium can rise and fall unhindered between the inner and outer tubes.The second surface of the capacitance consists of an electrically conductive film on the inner wall of a closed glass, ceramic or porcelain tube.
