In ATLAS an ultrasonic analysis technique has been developed to measure the fluorocarbon vapours in the cooling system of the inner detector. This technique has also been used to analyse the gas mixtures in semiconductor production, where often the amounts of heavy elements have to be controlled. The composition of the mixture is determined with a precision better than 1 part in 100,000. An application in clinical anaesthesia has been tested successfully indicating that typical clinical anaesthesia mixtures can be resolved with high precision. The analysis of hydrocarbons in oil refinery operations has also employed this technique. Ultrasound Gas Analysis Credits: Centre de Physique des Particules de Marseille (CPPM)