Separation of gases or vapours

The present invention relates to an improved apparatus for the separation of a fluid mixture, particularly an isotope mixture, into fractions by difference in mass. Apparatus for the separation nozzle method is described. The advantages of the system derive from the fact that the separating elements can be formed as a one-piece unit for each station or at most from two plates for each station, with especially high precision by electrodeposition techniques. They can be emplaced in the seats machined with equally high precision in the cast passage-forming body so that all of the tolerances can be preestablished in the separating element or by the precision of the machining of the fitting surfaces