A Bologna bottle, also known as a Bologna phial or philosophical vial, is a
glass bottle
A glass bottle is a bottle made from glass. Glass bottles can vary in size considerably, but are most commonly found in sizes ranging between about 200 millilitres and 1.5 litres. Common uses for glass bottles include food condiments, soda, liq ...
which has great external strength, often used in
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
demonstrations and
magic tricks
Magic, which encompasses the subgenres of illusion, stage magic, and close up magic, among others, is a performing art in which audiences are entertained by tricks, effects, or illusions of seemingly impossible feats, using natural means. It ...
. The exterior is generally strong enough that one could pound a nail into a block of wood using the bottle as a
hammer; however, even a small scratch on the interior would cause it to crumble.
It is created by heating a glass bottle and then rapidly cooling the outside whilst slowly cooling the inside. This causes external compression and internal tension such that even a scratch on the inside is sufficient to shatter the bottle.
The effect is utilized in several magic effects, including the "Devil's Flask".
Manufacture
To create the desired effect, the bottles are rapidly cooled on the outside and slow cooled on the inside during the glass-making process. This causes the outside to be extremely hard, and the inside to be soft and susceptible to damage which can release the powerful internal stresses. The glass is not
annealed. Reheating the glass and then allowing it to cool slowly will remove the unique properties from the glass.
Uses
Because of the seemingly paradoxical nature of the glass (being both extremely durable and extremely fragile), Bologna bottles are often used as
props
A prop, formally known as (theatrical) property, is an object used on stage or screen by actors during a performance or screen production. In practical terms, a prop is considered to be anything movable or portable on a stage or a set, distinc ...
in magic tricks, where the bottle can be shattered by rattling a small object inside it.
History
Mentioned in the publication of the Royal Society around 1740s, the Bologna bottle is named for where it was first discovered in Bologna, Italy. During this period, a glassblower would create a Bologna bottle by leaving the bottle in the open air instead of immediately placing the bottle back into the furnace to cool (
annealing). This produced a special phenomenon, where the bottle would remain intact even when dropped from a distance onto the brick floor, but would immediately rupture if a small piece of flint were placed inside.
The Philosophical Transactions and Collections – Royal society of London: Abridged and Disposed Under General Heads, Volume 10 (1743-1750). p. 1343
Although the bottle can resist a strong external force, the extremely fragile flaws inside the bottle prevent it from being used in practical applications.
See also
* List of bottle types, brands and companies
This is a list of bottle types, brands and companies. A bottle is a rigid container with a neck that is narrower than the body, and a "mouth". Bottles are often made of glass, clay, plastic, aluminum or other impervious materials, and are typical ...
* Prince Rupert's Drop
References
External links
A demonstration of the principle as a magic trick, using a coca-cola bottle as the vessel.
{{DEFAULTSORT:Bologna Bottle
Glass bottles
Glass engineering and science
Glass physics
Magic tricks
Prop design