Player's Handbook, Wizards of the Coast, p. 150, 151

Alchemist's Fire (flask)

Adventuring Gear Common

This sticky, adhesive fluid ignites when exposed to air. As an action, you can throw this flask up to 20 feet, shattering it on impact. Make a ranged attack against a creature or object, treating the alchemist's fire as an improvised weapon. On a hit, the target takes 1d4 fire damage at the start of each of its turns. A creature can end this damage by using its action to make a DC 10 Dexterity check to extinguish the flames.

Cost: 50 GP Weight: 1 lb. / 0.5 kg