A sensitive measuring scheme has been developed for capacitive-semiconductor converters of humidity of dispersed media, and basic static characteristics have been obtained depending on the duration of bipolar pulses, providing an increase in accuracy and linearity of the static characteristics. A scientifically based increase in the reliability of the results of chemical analysis and physicochemical measurements, the identification and minimization of their errors are impossible without the use of the foundations of metrology - the science of measurements. At the same time, theoretical metrology is rather closely intertwined with the legislative - a set of state acts and regulatory documents that regulate the rules, requirements and norms that must be guided by when making measurements. Obviously, the more responsible the decision is made on the basis of the measurement results, the more stringent the requirements are imposed on them, the less the measurement results should depend on the subjective opinion of the experimenter. Main provisions of measurement error assessment and principles of uniformity of measurements required for rational performance of physical and chemical measurements and chemical analysis are presented. Regularities of normal and other most common types of random v.e. distribution are considered.