Bone in vinegar is an item used during the Fur 'n' Seek wish list. It is made by using the skeletal wyvern tail-bone with a pot of vinegar. The bone in vinegar should be brought along with logs to the pot boiler near the Odd Old Man. The pot boiler should be lit with the logs, which will result in a polished skeletal wyvern tail-bone after 12 seconds.
Emptying the pot will return an empty pot, but destroy the skeletal wyvern tail-bone.