Abstract: A sealed adjusting device for mounting in the wall of a sealed instrument housing that includes at least one adjustable element, such as a potentiometer. The adjusting device comprises an elongated sleeve-like mounting hub capable of being sealingly secured in the housing wall, and a normally freely rotatable or freely turnable knob structured as a hollow capsule rotatably inserted onto one end of the mounting hub. The other end of the mounting hub receives or is connected with a portion of the adjustable element. A spring is provided within the mounting hub to hold the knob in its freely turnable or rotatable position. The knob is operatively connected with a clutch-sleeve for temporary engagement with the rotatable operating end of the adjustable element when the knob is pushed against the spring.

Abstract: Electroanalytic transducers for electrochemical analysis of chemical substances are disclosed. The transducers are of the type which include electrodes contacting an electrolyte solution. In accordance with the method and apparatus of the invention, means insulating an electrode are held in a mutually pressing engagement over preselected portions of the electrode to insulate that portion from the electrolyte and prevent creep of the electrolyte between the insulating means and the preselected portions. Thus, the surface area of the electrode exposed to the electrolyte is maintained substantially constant during the service life of the transducer. In a preferred embodiment, sensor or working and counter electrodes are coaxially mounted and circumferentially coaxially separated by annular insulating means. Spring means urge the inner coaxially mounted electrode and the annular insulating means together so that only the surface of the cross-sectional end of the inner electrode is exposed to electrolyte.