This test chamber is the eighth bonus level of the game. It is taken from Portal: The Flash Version MapPack. The challenges of this level are unlocked when the test chamber is completed once.
At the sliding door, use portals to get into the Rat Man den area; there is a turret guarding the way across.
Shoot a portal directly above the turret on the raised block and go through, knocking it over.
Turn around and shoot a portal behind the glass barrier.
Walk up to the top of the small non-portalable slope, turn around, and place a portal in the button area.
Once in the button area, press the pedestal button to have a new sphere come out of the Vital Aparatus Vent.
Once the sphere rolls down to the lower level, use portals to get it into the button area.
Walk up to the very edge of the button area and place a portal as close to the edge on the lower level as possible. Put the other portal on the angled panel.
Carefully drop the sphere through so it rolls down the narrow hallway and knocks over the turret at the end. Once it is done deactivating, jump through yourself.
Place the sphere on the button if it isn't already, then go back behind the glass barrier and through the hatch in the floor.
