Abstract: A circuit for measuring electrical properties such as the resistance, capacitance and inductance includes two bridge branches each having at least two serially-connected components which can comprise resistors, capacitors and inductors or combinations thereof. One of the components is variable with respect to its resistance by means of a quantity which is under measurement. The bridge branches are connected to different voltage outputs of a common alternating current supply. The diagonal points between serially-connected components in each of the bridge branches serve as measuring points for a measurable signal. Each measuring point may be connected by a line having a rectifier followed by a capacitor forming an electronic store such that at the output of the stores there is a direct current potential forming the measurable signal.

Abstract: Method and apparatus for simultaneously and continuously determining the total inorganic carbon, total organic carbon (TOC) and chemical oxygen demand (COD) of an aqueous sample. The method involves first converting all inorganic carbon to CO.sub.2, the amount of which is determined. The organic carbon is converted, by treatment with an excess of an oxidizing agent, into CO.sub.2, which is conductimetrically determined (TOC), and the amount of remaining oxidizing agent is determined in a redox cell to ascertain how much of the oxidizing agent was consumed by the organic carbon. This is the COD.