82 is fastened to the base plate 83 by means of screw 86 the manifold 78 is fastened to the base plate 83 by means of screw 87 any equivalent structure that creates a gas nozzle tangential to the interior of the curved surface may be used referring again to fig2 the near sonic air stream ejected from the converging diverging nozzle 81 is forced into the spiralling path 88 where most of its original energy is lost before escaping the air driven vortex 59 via exhaust passage 90 that extends along the longitudinal axis of the cylindrical exhaust manifold 91 it can be appreciated that the centrifugal effects of the air driven vortex 59 is to preferentially drive the large sonic velocity particles 62 against the cylindrical wall 72 the air exhausted by the exhaust manifold 91 is relatively enriched in small treatment particles 61 the exhausted particles 61 are replenished by a cylindrical supply tube 94 both apparatus 1 and 51 have the advantage of treating fabric continuously across the width and of recycling the treatment particles apparatus 51 has the additional advantage of efficiently utilizing all of the energy in the air stream and is immune to clogging the type of particle or particles to be used in both embodiments should be small high speed particles that could be in the form of a powder which have a hardness comparable to or less than that of the fiber this is so the fiber may undergo repeated impacts with breaking or.