Abstract: Disclosed is a pneumatically-driven volume controlled bellows pump apparatus for oscillating liquid into a localized area of the human body, preferably methyl-tertiary butyl ether or another solvent, into the gallbladder. The pump includes a fluid reservoir in the form of an inverted syringe attached via a stopcock to the bellows. The bellows is attached via a second stopcock to a catheter also attached to a priming syringe. An inlet pinch valve is disposed between the bellows and the fluid reservoir and an outlet pinch valve between the bellows and the fluid receiver.To use the pump, a pigtail catheter with outlets in the pigtail is inserted into the desired area of the body, preferably a receptacle such as the gallbladder, to introduce a selected volume of liquid for gallstone dissolution. Liquid is infused into the receptacle by decompression of the bellows with the inlet but not the outlet valve open and then by compression of the bellows with the outlet but not the inlet valve open.