Abstract: A method of regulating combustion by rapid-response monitoring of the gaseous effluents leaving a combustion chamber, especially the chamber of an internal-combustion engine, includes the steps of emitting ultraviolet radiation to a zone of small volume traversed by at least part of the gaseous effluents leaving the combustion chamber; receiving at least part of the ultraviolet radiation which has passed through this zone; measuring the degree to which the ultraviolet radiation has been absorbed by a chemical compound contained in the gaseous effluents; and governing at least one parameter influencing combustion within the combustion chamber as a function of the degree of absorption.

Abstract: A process and device for determining the composition of an alcohol-petrol mixture supplying a combustion engine. According to this process a light beam is emitted through the mixture supplying the engine, the degree to which this beam is absorbed by the mixture is determined in a wave length chosen in the wave length range corresponding to the near infra-red and adjustment of the operating parameters of the engine is controlled as a function of the degree of absorption thus measured.