A double-ply paper bag provided in the vicinity of its opening with a strip supporting closure means, said strip forming two substantially facing webs, with only of the two webs being fixed to the inside face of the inner ply of the bag prior to the bag being filled and closed. The present invention provides a novel process for the preparation of 3-3-phenylpropionaldehyde. A first mechanism releasably restrains the body from rotating, and a second mechanism is included for winding a spring about the cylindrical wall of the housing.