Empty Bottle

15 on Standard (Modern and Classic), 16 on Insanity. The first 3 are in ch02: the one that rolls towards you if you switch on the Prep Room light, the one in the Room 201 wardrobe and the one on the Nurses' Corridor table (with the Lighter). In ch03, the one on the Dining Room's west cabinet, behind the table.

Throw it to smash it and draw the enemies that hunt by sound: The Girl, the blind patients, the Licker β2. It is the ingredient of the Molotov Cocktail and the Bottle of Acid.

Keep the Dining Room one in the Item Box for Internal Dispute (ch03): in the Waiting Room, throw it at the zombie in the black dress while she stands by the blind patient and he will attack her. Smash one near Martin L. Case, the patient who can't stand noise, and he attacks whoever is next to him. Don't waste them: from the Basement on, each one is a Molotov Cocktail and, in the ARK, a Bottle of Acid.