Antibubble
Encyclopedia
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
surrounded by a thin film of gas
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
, as opposed to a gas bubble
Liquid bubble
A bubble is a globule of one substance in another, usually gas in a liquid.Due to the Marangoni effect, bubbles may remain intact when they reach the surface of the immersive substance.-Common examples:...
, which is a sphere of gas surrounded by a liquid. Antibubbles are formed when liquid drops or flows turbulently into the same or another liquid. They can either skim across the surface of a liquid such as water, in which case they are also called water globules, or they can be completely submerged into the liquid to which they are directed.
Background
Antibubbles are a common but widely unrecognized phenomenonPhenomenon
A phenomenon , plural phenomena, is any observable occurrence. Phenomena are often, but not always, understood as 'appearances' or 'experiences'...
, in part because of their resemblance to air bubbles, and in part because of their typically transient, or short-lived, nature. With certain (soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
y) solutions, they can be made to last much longer.
Antibubbles can be created by allowing a tap to drip into a container of water to which a drop or two of soap has been added, although it must be noted that antibubbles, being inherently unstable, are difficult to form. The soap reduces the water's surface tension and allows the skin of air surrounding the droplet to remain in place for more than just a fraction of a second.
Just as soap bubble
Soap bubble
A soap bubble is a thin film of soapy water enclosing air, that forms a hollow sphere with an iridescent surface. Soap bubbles usually last for only a few seconds before bursting, either on their own or on contact with another object. They are often used for children's enjoyment, but they are also...
s, with air inside and air outside, have negative buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
and tend to sink towards the ground, so antibubbles, with water inside and water outside have positive buoyancy and tend to rise towards the water surface. But again, just as soap bubbles can be filled with a lighter gas to give them positive buoyancy, so antibubbles can be filled with a heavier liquid to give them negative buoyancy. Using a drinking straw
Drinking straw
A drinking straw is a short tube intended for transferring a beverage from its container to the mouth of the drinker by use of suction. A thin tube of plastic or other material, straight or with an accordion-like living hinge, it is employed by being held with one end in the mouth and another end...
to drop droplets of sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
solution onto soapy water will produce antibubbles that sink.
Antibubbles usually pop when they touch the bottom or the side of the vessel containing the liquid. This can be prevented by tipping a few teaspoons of sugar into the soapy water and giving it some time to dissolve (but without stirring it). This will produce a denser layer of sugary water at the bottom of the container. Antibubbles made from sugar solution will then sink through the water and rest on top of the denser layer at the bottom. Antibubbles made this way can last for several minutes.
The layers of an antibubble are water, which it is submerged in, air, and the water trapped in the air.
Differences between air bubbles and antibubbles
The behavior of antibubbles differs from that of air bubbles in three primary ways, and provides a ready means of identification:- Antibubbles are held in place by surface tensionSurface tensionSurface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
, and move rapidly across the surface of the water. They can also be seen to ricochet off other objects in the water (such as air bubbles) and off the sides of a container in a manner similar to that of billiard balls.
- Under ordinary circumstances, antibubbles are short-lived. An air bubble with a soap skin may last several minutes. Antibubbles often have lifetimes of a few seconds or less; however, if the electrical potential between the inner and outer fluid is equalized, antibubbles can last as long as, or longer than, air bubbles.
- Antibubbles refract light in a different manner than air bubbles. Because they are water droplets, light entering them is refracted back toward its source in the same manner as rainbows are produced. Because of this refraction, antibubbles have a bright appearance.
Potential uses for antibubbles
If antibubbles can be stabilized they can be used to form a long lasting froth — antifoam. Possible uses for antifoam are as a lubricantLubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...
or leveraging the thin passageways permeating antifoam as a filter for air or other gasses.
Antibubbles themselves could be used for chemical processes such as removing pollutants from a smokestack. Replacing the air in antibubble shells with another liquid could be used for a drug delivery system by creating a shell of liquid-polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
around a drug. Hardening the polymer with ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
light would create a drug filled capsule.