Abstract: An artificial lifting device has a downhole valve which intermittently directs operating gas to the top of a collection chamber to promote the lifting of oil below the valve upwardly through an annulus defined between a cylindrical housing supporting the valve and an external cylindrical member through which the housing extends. Gas is alternately injected to the top of the chamber through an injection port and vented to the surface through a vent port. An exhaust conduit, separate from the source of pressurized gas running from the surface to the valve, communicates the vent port with the surface when the device is in the vent mode.