Abstract: In an apparatus for the volumetric metering of fluid, pasty and/or powdery substances, in particular for separating small amounts of substance from a delivery flow, by means of an adjustable-volume measurement chamber which is connected to a feed conduit and which is provided with an outlet, a capillary measurement conduit (22) is connected as the measurement chamber to a vacuum conduit (33). In particular cases the measurement conduit can be acted upon by conveyor air, but in the normal case it is provided with a metering needle which is displaceable therein and whose free needle end (19) delimits the measurement chamber at one end. In addition a movable sealing body (56) is to be associated as a closure element with the mouth opening (23) of the measurement conduit (22), that serves as the outlet, which sealing body can be connected to a closure device (50) which is limitedly rotatable about a pivot means (52).