1297041 Separating gaseous mixtures BERTIN & CIE and ENTREPRISE DE RECHERCHES ET D'ACTIVITES PETROLIERES-ELF 3 Aug 1970 [11 Aug 1969] 37381/70 Heading B1L Gas mixtures containing components having different atomic or molecular weights are separated by passage under pressure through orifice 3 at supersonic velocity into chamber 4. Pilot circuits 9, 10 which also open into chamber 4 act as a fluidic flip-flop, causing the effluent stream from orifice 3 to oscillate uniformly and continuously across inlet orifices 5 of tubes 8 from one extreme position to the other (see also Fig. 4, not shown). As the stream sweeps across the orifice 5 of any one tube a wave pulse of the mixture passes into the tube in which a partial mass separation occurs, in consequence of which a fraction enriched in the heavier components is removed by tube 18, while the fraction enriched in lighter components is collected at the outlet 8c of tubes 8. Stage enrichment of a few tenths % were obtained in separating air into O 2 and N 2 , and in separating <SP>36</SP>A and <SP>40</SP>A. The separation units may be employed in cascades.