Abstract: An apparatus for automatically dispensing a measured volume of liquid has a cylinder and a piston. The liquid is fed to one end of the cylinder and displaces the piston which expels from the other end of the cylinder a quantity of liquid proportional to the piston stroke. At the end of the stroke, the piston abuts and closes a switch which actuates an electric motor driving a four-way rotary valve to reverse the liquid flow direction in the cylinder, whereby the piston moves in the opposite direction to discharge a measured amount of the liquid which was previously used to push the piston. The piston, at the end of its second stroke, again strikes and causes the closing of a second electric switch which produces rotation of the four-way valve to again reverse the liquid flow to its original direction.