Abstract: An apparatus for the registration of the humidity and acid content of a refrigerant or another non-polar liquid including a capacitive sensing element placed in the refrigerant or liquid and connected to an electrical evaluation circuit, the electrodes of the capacitive sensing element being formed of two different metals having different normal potentials, and the electrical circuit includes circuit elements for determining the resistive loss in the capacitive sensing element and circuit breakers for determining the current delivered by the sensing element.