If Harry finished the potion, how could Dumbledore get past the black flames?

Question

To get through to the final chamber containing the Philosopher's Stone Harry and Hermione have to defeat Snape's logic challenge. When Hermione discovers the correct potion they find that there is only a small quantity remaining.

"Got it," she said. "The smallest bottle will get us through the black fire - towards the Stone."
Harry looked at the tiny bottle.
"There's only enough there for one of us," he said. "That's hardly one swallow."
_{(Philosopher's Stone, Chapter 16, Through the Trapdoor).}

I've always assumed that there wasn't much potion left because Quirrell had already consumed part of it to gain access himself. Yet Dumbledore later went through the flames to rescue Harry from Quirrell. He did this despite it being made perfectly clear that Harry had finished the potion.

"Here I come," he said and he drained the little bottle in one gulp.
_{(Philosopher's Stone, Chapter 16, Through the Trapdoor).}

How then did Dumbledore get through the challenge? Did the bottle refill itself every time the potion was drunk (but contained a small quantity of potion so as to only allow one person entry)? Or did Dumbledore have some kind of 'cheat code' that allowed him to bypass having to drink the potion at all?

Answer 1

I think your assumptions are flawed in two ways.

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Assumption 1: The bottle was mostly drained.

It's much more likely that the bottle only contained enough potion for one, and that it had reset itself after Quirrell drank from it. The chessboard, for example, had definitely reset itself.

They were standing on the edge of a huge chessboard, behind the black chessmen, which were all taller than they were and carved from what looked like black stone. Facing them, way across the chamber, were white pieces-- the towering white chessmen had no faces.

...

Their first real shock came when their other knight was taken. The white queen smashed him to the floor and dragged him off the board, where he lay quite still, face down.
_{Harry Potter and the Philosopher's Stone}

Clearly, the pieces had recovered after Quirrell's match.

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Assumption 2: Dumbledore needed the potion to bypass the flames.

Dumbledore had numerous other methods at his disposal to get around Hogwarts. Aside from any other ways of getting past them, there are three ways I know of that he might have Apparated straight into the chamber, even inside Hogwarts.

Phoenix magic:

Fawkes circled the office and swooped low over him. Dumbledore released Harry, raised his hand and grasped the phoenix's long golden tail. There was a flash of fire and the pair of them were gone.
_{Harry Potter and the Order of the Phoenix}

House-elf magic:

"Dobby must go!" breathed the elf, terrified; there was a loud crack, and Harry's fist was suddenly clenched on thin air. He slumped back into bed, his eyes on the dark doorway to the hospital wing as the footsteps drew nearer.
_{Harry Potter and the Chamber of Secrets}

Lifting the Apparition barrier in that area:

"As you may know, it is usually impossible to Apparate or Disapparate within Hogwarts. The Headmaster has lifted this enchantment, purely within the Great Hall, for one hour, so as to enable you to practise. May I emphasise that you will not be able to Apparate outside the walls of this Hall, and that you would be unwise to try."
_{Harry Potter and the Half-Blood Prince}

So even if the potion hadn't refilled, I don't think Dumbledore was the least bit hindered by that obstacle.

Answer 2

I would imagine that the potions refill. If they do not refill then when Harry and Hermione arrived in the potions room they would have seen that one bottle was half empty and known that that was the correct one, just like in the room with the keys:

Not for nothing, though, was Harry the youngest Seeker in a century. He had a knack for spotting things other people didn’t. After a minute’s weaving about through the whirl of rainbow feathers, he noticed a large silver key that had a bent wing, as if it had already been caught and stuffed roughly into the keyhole.

We do not find that they noticed anything different about the correct bottle, and in fact Harry was still skeptical that it was the correct one:

“You drink first,” said Harry. “You are sure which is which, aren’t you?”

It would thus seem that they were unable to determine the correct bottle by noticing one that had already been used; therefore, it stands to reason that the bottle refilled itself.

Of course one could argue that the bottle was in fact half empty but Harry and Hermione did not think of using such evidence. However, this is probably unlikely as this is precisely where we find out that Hermione's logical reasoning exceeds the average wizard:

“Brilliant,” said Hermione. “This isn’t magic — it’s logic — a puzzle. A lot of the greatest wizards haven’t got an ounce of logic, they’d be stuck in here forever.”

“But so will we, won’t we?”

“Of course not,” said Hermione.

Answer 3

The bottle has to refill, once the room has emptied, or possibly when all the obstacles do (the chess set has to reset at some point) if it doesn't then Harry couldn't have followed Quirrel in the first place (and if it refilled as soon as it was put down then there's no point in having a one person portion since any number could use it simply by drinking it and putting in back on the table), Quirrel arrived and won through all the obstacles before Harry, Ron and Hermione arrived and only stalled out because he didn't understand the mirror. In getting to the mirror Quirrel had to empty that potion bottle so what Harry drank had to be a refill, that being the case Dumbledore can also drink a refill; or, since he helped set up the obstacle course in the first place, walk through it using built-in bypasses and not need any potion.

Answer 4

Snape provided more potion.

It is clear that Snape is up to speed on Quirrells and has shown great presence of mind regarding his plans to steal the Philosophers Stone. Noticing Dumbledore is gone and Quirrell is missing he knows what Quirrell is doing. He suspected Harry and the others were up to something and they even mentioned the Stone to Mcgonagall so it is very likely he understands what is about to happen.

From there there are 3 options for him:

1. try to stop Quirrel before he gets to the hatch
2. try to race him through the traps and stop him in the dungeon
3. damage control.

Once he saw Fluffy asleep option 1 was dead. He knows that option 2 might put him face to face(-ish) with Voldemort becaus Quirrel is close to his endgame. There might also be interference from Harry and there would be no time to try and convince them That leaves option 3.

The potion puzzle is clearly his doing and he knows that there isn't much of the protection potion. It would be obvious that the potion would be spent after 1 or 2 portions (depending on how much chance he gives three firstyears). Wasting Dumbledores time with a riddle also wouldn't be a good idea in a crisis. So in accordance with option 3 he either made or retrieved some more protection potion and handed it to Dumbledore and the rest of the rescue party upon Dumbledore arrival.

Answer 5

My personal opinion:

I really doubt that Quirrel, possessed by Lord Voldemort, would really have played a chess game or tried to catch a key, while on a broom, or tried to solve a puzzle. It would be a really strange thing to do. In my opinion, Quirrel knew, or was suggested, magic to skip these tasks. I just can't draw a game of chess played by Quirrel, in my head. Possibly the key was summoned using dark magic and the Potion might have been with Quirrel before he went there, or maybe he found out about a way to do it without a Potion. Remember how he found about the way to get past Fluffy, the three-headed dog? What prevented him to try to find out the other secrets?

As for a more logical explanation for Dumbledore, I guess, he, as one of the makers of the task queue, could have known all the back doors, shortcuts or other stuff, must have, he's the boss actually too. So he shouldn't have had any problem getting to rescue Harry.

Answer 6

Snape does challenge Quirrell in the forest but he wouldn't have brought Dumbledore into the situation, due to fears of what would happen to Snape if he had knowingly stopped Voldemort's return to power. Dumbledore could have also used Fawkes's phoenix tear healing power if he got badly burnt by walking through the flames or by the chess game.

However, I think the fact that Dumbledore is the "keeper" for the Philosopher's Stone allows him to bypass everything, a bit like a secret keeper can be the only one to see a place if they like. From the impression I get from the book he just went straight to Harry, no trouble!