He explains to the Dragonborn that the White Phial is a magical vessel made from Unmelting Snow gathered at the Throat of the World and that it purifies, amplifies and refills any liquid placed within it; the ultimate embodiment of Alchemy itself.
He has finally discovered its location but is too old, sickly and dying to retrieve it on his own. He now must reluctantly seek the aid of the Dragonborn in his quest to recover it.
Upon accepting the quest from Nurelion, he will produce Nurelion's Mixture to help gain access to the Phial. It is learned that the Forsaken Cave is the final resting place of his coveted phial and that the cave is located west of Windhelm.
The cave is primarily populated with Draugr. In fact, it is more of a Nordic crypt than a cave. Continuing through the cave and into the Forsaken Crypt, one will encounter the burial chamber of Curalmil, a strong Draugr Overlord or even a Dragon Priest, as well as a small cadre of his minions. They are the final guardians of the White Phial, as well as a Word Wall.
Finding the Phial
An Ancient Bowl placed atop a pedestal will be encountered after continuing through the passage directly beneath the Word Wall. Filling it with Nurelion's Mixture will reveal the doorway into the sanctum of the White Phial. Displayed prominently in the room is the Phial along with a number of various alchemical reagents and an Alchemy Lab. However, upon closer inspection, the Phial has unfortunately been damaged.
Returning with the Phial
Upon returning to his shop in Windhelm, Nurelion is heard complaining somewhere as usual, not in a good mood and perhaps having become even sicker than before. Upon inspecting the Phial, he is livid that the Phial is cracked and vociferates at having sent such a clumsy adventurer to retrieve his life's ambition. He then rescinds after realizing the power and intelligence that would be needed to damage such an item... which is surely not the present case. With his lifetime dream broken, he is crushed and only manages to reward the Dovahkiin with a lousy five Septims.
Nurelion's apprentice Quintus is much more sympathetic to the ordeal of actually retrieving the Phial from such a dangerous place, he explains that Nurelion isn't well and parts with a more reasonable reward of 500 Septims.
This section contains bugs related to The White Phial (Quest). Before adding a bug to this list, consider the following:
The Phial can disappear if you leave the dungeon without taking it. At the completion of the quest, even when "asleep and dying" on his bed, you can still hear Nurelion continuing his standard dialogue about not liking loiterers and those who gawk at his goods. It is possible to receive double the amount that Quintus gives you as a reward from 500 to 1000 gold. Often when you finish the initial dialogue with Nurelion too quickly (without exiting during middle of the dialogue), he will repeat the same dialogue if you do not exit the second dialogue, which would result in a duplication of the 500 gold rewarded.
The alchemist of Windhelm, Nurelion, has asked me to find the legendary White Phial for him.
I retrieved the White Phial for Nurelion, but it was damaged beyond repair. His assistant, Quintus, still paid me my reward, though.