Abstract: A device for use in the mixing of fluids, e.g. the gasification of liquids, comprises an elongate member including an internal passage; and, mounted on the elongate member via radials arms, one or more venturi members each having a convergent-divergent duct whose axis is substantially tangential to the elongate member, and in which the neck of the duct has an opening in communication, via passages in the radial, with the internal passage. On rotation of the device, reduced pressure in the duct neck draws fluid down the shaft of the elongate member.