A nozzle for injecting a first liquid mass into a stream of second liquid mass flowing within a pipe, comprising a first, outer, cylinder and second, inner, cylinder concentrically arranged about a nozzle axis, securing means for securing the nozzle to a wall of the pipe with the nozzle axis orthogonal to the pipe wall, the nozzle projecting into an interior of the pipe in use, duct means for receiving the first liquid mass and transporting it to the interior of the inner and outer cylinders, the inner cylinder comprising at least one hole arranged to expel liquid therethrough, and the outer cylinder comprising at least one hole arranged to expel liquid therethrough.