Abstract: Longitudinally collapsible apparatus for compacting packing material within a tubular liquid chromatography column. The apparatus includes a first support member, a second support member and a movable support member. The movable support member is releasably connectable to the second support member for support thereby. When released from the second support member, the movable member is adapted to ride on guide members extending between the first and second support members. A compression mechanism is supported on the movable support member to mote therewith to a longitudinally collapsed position for the apparatus. The compression mechanism comprises a reversible drive for an axially movable rod carrying a movable piston. With the movable support member secured to the second support member, the piston of the compression mechanism is movable in an end of the tubular column when the column is supported on the first support member.