All seems to be as it should in the Potions laboratory; however, those who need to use a certain item might notice that they have decreased in number.

Glancing over at the shelves you may notice that several phials that were there just the day before are nowhere to be seen. Perhaps someone recently used them for a fairly large brew? Or maybe the house-elves had taken them for cleaning?

Nothing has been recorded in the logbook and, for those that try, summoning them proves ineffective. Where, oh where, could those missing phials have gone?

If you have your own phials or just don't care to pay attention to such minor things, you would be totally oblivious that anything in the room is missing.