Potassium Nitrate

• Type: Potion Ingredient
• Known Users: Draco Malfoy
• Source: Presumably part of the standard Hogwarts School Stock for Potions classes.

Potassium nitrate is a chemical compound used as an ingredient in Potion-making. Its physical appearance is not described in the novels, though its real-world Muggle counterpart, also known as saltpeter, is a white crystalline solid. Its precise magical function is not explicitly stated. However, its use by Draco Malfoy as an unlisted additive in a Shrinking Solution suggests it acts as an altering agent or enhancer. When Malfoy added it to his potion, the solution turned a “shimmering, silvery color” instead of the “acid green” color specified in Libatius Borage's textbook, Magical Drafts and Potions. This indicates that potassium nitrate can significantly change a potion's physical and possibly magical properties, representing a more advanced or non-standard brewing technique.

Potassium nitrate is mentioned only once in the series, during a fourth-year Potions lesson in Harry Potter and the Goblet of Fire. While the class was brewing Shrinking Solutions, Ron Weasley observed Draco Malfoy adding extra, unauthorized ingredients to his cauldron and identified one of them as potassium nitrate. This brief moment serves several narrative purposes:

• It highlights the ongoing rivalry between Harry Potter's trio and Malfoy, particularly in the academic setting of Potions.
• It demonstrates Malfoy's competence and ambition in Potions, showing his willingness to deviate from the textbook instructions to achieve a superior, or at least different, result.
• It underscores Harry's and Ron's relative struggles in the subject, contrasting their by-the-book difficulties with Malfoy's confident experimentation and Hermione Granger's precise adherence to instructions.

In real-world Muggle chemistry, potassium nitrate (KNO₃), commonly called saltpeter, is a primary ingredient in the manufacture of gunpowder. Its inclusion in the wizarding world as a Potion ingredient may be a subtle nod to its volatile and powerful nature, reflecting Malfoy's use of a potentially risky but effective ingredient to get ahead.