The demonstration is performed with a dry five-gallon (20-Litre)water jug. A volume of 5.0 mL of methanol is added to the jug. The jug is capped and shaken for 30 seconds. After removing the top, excess ethanol is shaken from the jug, and placed in a stoppered container away from the demonstration table. Since these âÂÂWhoosh BottleâÂÂ demonstrations have caused a variety of accidents, it is imperative to protect against shattering when the ignition of the vapor in the jug occurs. After removing the top and drying the opening of the jug, place the jug on its side under the protection of a small three-sided safety shield1 that is lying on its side on the bench top. This allows for protection of both the demonstrator and audience when ignition occurs.
The demonstration is used to discuss the combustion process. I normally first ignite a small volume of ethanol on a watch glass (behind a safety shield) to describe the slow burning process of the vapors. This provides a sharp contrast to the ignition of a small volume of methanol vaporized in the jug. A variety of combustion/detonation processes may then be discussed.
1. The standard three-sided safety shield, which is recommended for use in performing any hazardous demonstrations