Abstract: A manually operated dispenser for dispensing a predetermined amount of powdered substance comprises a pressure cylinder (2) with an axially displaceable piston (3). A super-atmospheric pressure is generated by displacing the piston inwardly in the cylinder and is releaved through a chamber (41) in a magazine (40) comprising a number of chambers (41) containing powdered substance. The ends of the chambers (41) are covered by penetrable membranes (48), and the chambers (41) may be moved to successively being in alignment with a penetrator (30) and an outlet pipe (46). When the piston (3) is in its inner-most position the penetrator (30) and the inlet end of the out-let pipe (46) are forced through the respective membranes (48) at the ends of the chamber (41), and the subatmospheric pressure is releaved through the chamber (41) to dispense its content through the outlet pipe (46).