question: How does a Lava Lamp work?
comment: The “lava” heats up and expands slightly decreasing its density. Which it is already close to the rest of the liquids density. When it becomes lower than the other liquid it starts to float which moves it further from the heat source and then becomes more sense and causing it to fall back down.
passages: Section::::Operation.
  
  A classic lava lamp contains a standard incandescent or halogen lamp which heats a tall (often tapered) glass bottle. A formula from a 1968 US patent consisted of water and a transparent, translucent, or opaque mix of mineral oil, paraffin wax, and carbon tetrachloride. The clear water or mineral oil can optionally be coloured with transparent dyes.
   A lava lamp (or astro lamp) is a decorative lamp, invented in 1963 by British entrepreneur Edward Craven Walker the founder of the British lighting company Mathmos. The lamp consists of a bolus of a special coloured wax mixture inside a glass vessel, the remainder of which contains clear or translucent liquid; the vessel is then placed on a box containing an incandescent light bulb whose heat causes temporary reductions in the density of the wax and surface tension of the liquid. The warmed wax rises through the surrounding liquid, cools, loses its buoyancy, and falls back to the bottom of the vessel in a cycle that is visually suggestive of pāhoehoe lava, hence the name. The lamps are designed in a variety of styles and colours.
   The bulb is normally 25 to 40 watts. Generally, it will take 45–60 minutes for the wax to warm up enough to form freely rising blobs, when operating the lamp at standard room temperature. It may take as long as 2 to 3 hours if the room is below standard room temperature.
   In 2015, a new design was introduced into the market that uses ferrofluid in place of wax.
  
  Section::::History.
   In 1965, two men named Adolph Wertheimer and Hy Spector were intrigued by Walker's product when they saw it at a German trade show. They bought the American rights and began the Lava Manufacturing Corporation in Chicago, Illinois to sell what they called the Lava Lite Lamp. In the late 1970s, the US rights were sold to Larry Haggerty, who created a subsidiary of his company, Haggerty Enterprises, called Lava World International, which produced American lava lamps for over 30 years.
   Mathmos
  
  Mathmos is a British company that sells lighting products, most famously the lava lamp invented by its founder Edward Craven Walker. It is headquartered in its factory in Poole, Dorset.
  
  Section::::Company history.
  
  The Astro lamp, or lava lamp, was invented around 1963 by Edward Craven Walker. It was adapted from a design for an egg timer spotted in a pub in Dorset, England. Edward and Christine Craven-Walker licensed the product to a number of overseas markets whilst continuing to manufacture for the European market themselves under the original name of the company, Crestworth.
   British entrepreneur Edward Craven-Walker had the idea for the lava lamp in 1963 after watching a homemade egg timer, which was made from a cocktail shaker filled with liquids, as it was bubbling on a stove top in a pub. He hired British inventor David George Smith to develop the device and the chemical formula required put his idea into practice. Smith is credited as the inventor on the original for a "Display Device", that was filed and assigned to Craven-Walker's company in 1965, and subsequently issued in 1968. Craven-Walker's company was named Crestworth and was based in Poole, Dorset, in the United Kingdom. Craven-Walker named the lamp "Astro" and had variations such as the "Astro Mini" and the "Astro Coach" lantern.
   The rights to produce and sell the lamp on the American market for the duration of the patent were sold to Lava Simplex International, in 1966. The American company has now closed the American factory and has the lava lamps made in China.
  
  In Europe Craven-Walker’s original lava lamp designs have been in continuous production since the early 1960s and are still made today by Mathmos in Poole, Dorset, UK. The Mathmos lava lamp formula developed initially by Craven-Walker in the 1960s and then improved with his help in the 1990s is still used.
   Craven-Walker retained the rights for the rest of the world, and took on two business partners in the late 1980s named Cressida Granger and David Mulley. Eventually Granger and Mulley took over the company and they changed the name to Mathmos in 1992. Edward Craven-Walker remained a consultant until his death in 2000. Mathmos continues to make Lava Lamps and related products. Mathmos won two Queens Awards for Export, as well as Best Multi-Media prize at the Design Week awards. Astro lava lamp was launched in 1963 and celebrated its 50th anniversary in 2013. Mathmos lava lamps are still made in the original factory in Poole, Dorset.
   In 2003, American lava lamp maker, Lava World International (formerly known as Lava-Simplex-Scribe Internationale), shipped production to China. In 2008, they were acquired by Talon Merchant Capital and the name was again changed to Lava Lite LLC. As of 2016, lava lamps were being sold under Lifespan brands in North America. In 2018, the 'Lava Lamp' brand was acquired by toy and gift maker, Schylling Inc. of North Andover, MA.
  
  Section::::See also.
  
  BULLET::::- Lava
  
  BULLET::::- Lavarand, a random number generator that used lava lamps
  
  BULLET::::- Plasma globe
  
  BULLET::::- Bubble light
  
  Section::::External links.
  
  BULLET::::- Official site (UK)
   Common wax has a density much lower than that of water, and would float on top under any temperature. However, carbon tetrachloride is heavier than water (also nonflammable and miscible with wax) and is added to the wax to make its density at room temperature slightly higher than that of the water. When heated, the wax mixture becomes less dense than the water, because the wax expands more than water when both are heated. It also becomes fluid, and blobs of wax ascend to the top of the device where they cool (which increases their density relative to that of the water) and then they descend. A metallic wire coil in the base of the bottle acts as a surface tension breaker to recombine the cooled blobs of wax after they descend.
   Once the wax is molten, the lamp should not be shaken or knocked over or the two fluids may emulsify, and the fluid surrounding the wax blobs will remain cloudy rather than clear. Some recombination will occur as part of the normal cycle of the wax in the container, but the only means to recombine all of the wax is to turn off the lamp and wait a few hours. The wax will settle back down at the bottom, forming one blob once again. Severe cases can require many heat-cool cycles to clear.
   However, lava lamps made in China for the US market since 1970 do not use carbon tetrachloride, because its use was banned that year due to toxicity. The manufacturer (Haggerty) stated that their current formulation is a trade secret.
  
  The underlying fluid mechanics phenomenon is a form of Rayleigh–Taylor instability.
   Aeolipile
  
  An aeolipile (or aeolipyle, or eolipile), also known as a Hero's engine, is a simple bladeless radial steam turbine which spins when the central water container is heated. Torque is produced by steam jets exiting the turbine, much like a tip jet or rocket engine. In the 1st century AD, Hero of Alexandria described the device in Roman Egypt, and many sources give him the credit for its invention.
   BULLET::::- How I Beat The Odds: Cressida Granger of lava lamp pioneer Mathmos, Management Today, October 2013
  
  BULLET::::- The Secret History Of: The Lava lamp The Independent
  
  BULLET::::- Dyson to advise government BBC
  
  BULLET::::- My new media - The Guardian 
  
  BULLET::::- The Times
  
  BULLET::::- Modern retro - Design Week
  
  BULLET::::- British manufacturing Renaissance - ICON Magazine
  
  BULLET::::- Mathmos' Story
  
  BULLET::::- Lava lamp creators mark 50 years of 1960s icon, BBC News, Aug 2013
  
  BULLET::::- Far out, man: world’s largest lava lamp on show at the South Bank, Time Out, September 11, 2013
   Lava balloon
  
  A lava balloon is a gas-filled bubble of lava that floats on the sea surface. It can be up to several metres in size. When it emerges from the sea, it is usually hot and often steaming. After floating for some time it fills with water and sinks again.
   Fuming is a technique that has been developed in the past 15 years and was popularized by Bob Snodgrass. Fuming consists of heating silver or gold in the flame, so that the metals vaporize or "fume" microscopically thin layers of particles onto the glass. These particles stick to the hot glass surface changing its color with interesting effects. Silver turns clear glass into a yellowish color, giving shades of blues and greens when backed with a dark color, while gold turns clear glass shades of pinks and reds. The precious metal coating becomes increasingly visible the more the glass is fumed.
   Mathmos’ lava lamp sales have been through a number of ups and downs. After selling millions of lamps worldwide in the 1960s and 70s they did not revive until the 1990s. In 1989, Cressida Granger and David Mulley took over the running of Walker's original company, Crestworth, situated in Poole, Dorset, and changed the name to Mathmos in 1992.
  
  The name Mathmos comes from the seething lake of lava beneath the city Sogo in the 1962 comic "Barbarella".
   A red-hot surface can also be used to provide ignition. Such igniters are often made of silicon carbide, silicon nitride, or another material that is durable under prolonged exposure to extreme heat. Hot-surface igniters are commonly used in cooking ovens, boilers, and modern gas furnaces.
   Section::::Impact.
   Typically, and as Hero described the device, the water is heated in a simple boiler which forms part of a stand for the rotating vessel. Where this is the case, the boiler is connected to the rotating chamber by a pair of pipes that also serve as the pivots for the chamber. Alternatively the rotating chamber may itself serve as the boiler, and this arrangement greatly simplifies the pivot/bearing arrangements, as they then do not need to pass steam. This can be seen in the illustration of a classroom model shown here.
  
  Section::::History.
   Astro lamp has been in continuous production for 50 years and has been handmade in Britain since 1963. and is still made today by Mathmos in Poole. The Mathmos lava lamp formula developed initially by Craven Walker in the 1960s and then improved with his help in the 1990s is still used. His lava lamp company Mathmos celebrated its 50th anniversary in 2013.
  
  Section::::Naturism.
   Section::::Ballast operation.
   Section::::Ballasts.
  
  In the older style (but still most popular) "choke ballast", each end of the lamp has its own cathode and anode, however, once the lamp has started, the plasma flows from one end of the lamp to the other, with each end acting as a single cathode or anode. The starter is a plasma switch itself, and temporarily connects the cathode on one end of the lamp to the anode on the other end of the lamp, causing the lamp ends to heat up quickly, or "preheat". Many F71 lamps are still called "pre-heat bi-pin" for this reason.
   A kerosene lantern, also known as a "barn lantern" or "hurricane lantern", is a flat-wick lamp made for portable and outdoor use. They are made of soldered or crimped-together sheet-metal stampings, with tin-plated sheet steel being the most common material, followed by brass and copper. There are three types: dead-flame, hot-blast, and cold-blast. Both hot-blast and cold-blast designs are called tubular lanterns and are safer than dead-flame lamps, as tipping over a tubular lantern cuts off the oxygen flow to the burner and will extinguish the flame within seconds.
  