Abstract: A volumetric apparatus for milk (FIG. 1) for use by milking plants in the direct measurement of the quantity of milk collected from a cow in milking. The instrument comprises a vacuum separating chamber 1 for separation of the milk from the milk-air mixture drawn from the cow and, following said separating chamber, a measuring chamber 7 for the milk which at its lower end is provided with a milk outlet opening 15 and a valve plug 16 for selectively closing of said outlet opening. The measuring chamber is outfitted with a measuring means, and the separating chamber 1 is connected to the measuring chamber (7) through a constantly open inlet opening (6) of such size that the same pressure prevails in both chambers throughout the measuring operation. A collecting means follows the measuring chamber and communicates with the measuring chamber for receiving milk therefrom when the outlet opening 15 is opened by the valve plug.