If you follow the narrow stone staircase leading from the Entrance Hall to the dungeons, the entrance to the Potion Master's office is halfway down the cold passageway leading from the foot of that staircase locating the office adjacent to the Potions classroom.
The walls of the store room, which are in shadow, are lined with glass jars, including the wall behind the Potion Master's desk. Each jar contains some potion (differently coloured in different jars) in which is suspended slimy bits of some animal or plant (different ones in different jars).
There is also cupboard in one corner containing the private stores of potion ingredients
