In order to deliver porous particulate material into a cavity via a thin tube without substantially crushing the porous particulate material, a two-step process and an apparatus for use therein are provided. The two-step process involves inserting a first rod into the thin tube to push the porous particulate material therein； removing the first rod from the tube； and (a) inserting a second rod into the thin tube, or (b) joining a second rod with the first rod, and inserting the joined first rod and second rod, to push the porous particulate material which remains in the thin tube. In (a), the first rod has a cross sectional area significantly smaller than that of the thin tube, and the second rod has a cross sectional area which is about equal to that of the thin tube. In (b), each of the first rod and the second rod has a cross sectional area about half of the thin tube.
