Dispenser for dispensing liquids in controlled quantities from a bottle

A dispenser for dispensing controlled quantities of liquid from a bottle includes a piston, which is movable in a cylinder and serves to suck and discharge an adjustable quantity of liquid. The cylinder is secured to a valve block, which contains a suction valve and a discharge valve. A cylindrical sleeve surrounds the cylinder and defines an annular clearance therewith. To change the length of the stroke of the piston and the quantity of liquid which is to be sucked and discharged depends on the stroke length, an adjustable stop and a fixed stop, which is engageable with the adjustable stop and are accommodated in the clearance. In order to simplify the design of such dispenser and to improve the correctness, accuracy and reproducibility of its adjustment in that the characteristics are rendered independent from the subjective reliability of the operator, and to permit the variable and correctly reproducible adjustment for a desired quantity of liquid to be effected in a simpler manner and quicker, the two stops are axially fixed relative to the piston and the cylinder. To permit a change of the length of the stroke of the piston, the adjustable stop is rotatably mounted in the dispenser and is adapted to be releasably locked in each of a plurality of adjusted angular positions by resilient detents.