The following is designated as Open Game Content per the Open Game License.
Double Bottle of Analysis
The double bottle of analysis appears as a bottle with two necks that empty into the same two-quart space. In reality the volume of the vessel is bisected by an invisible force field that separates the volume into two one-quart volumes, each one served by one of the bottle necks. When the command word is spoken, the field will dissappear and allow the contents of the two spaces to mix. The true purpose of the double bottle of analysis is to test the miscibility of magic potions. When two different potions are poured into the bottle through the two necks, the user can hold the bottle and determine the possible outcome of mixing the two together. The Dungeon Master rolls twice on the Potion Miscibility Table and gives both results to the player. Only one of the results is the actual outcome of mixing the two potions, so the player will have to weigh his options before deciding whether or not to allow the potions to mix. If the decision to mix the potions is made, the DM rolls a d4; on a 1 or 2 the first result occurs, on a 3 or 4 the second.