How to make a lava lamp with your own hands
The story of lava lamps began in the 1960s when a simple accountant Edward Craven Walker filed a patent application for a lighting fixture with an exciting visual effect. Walker's original recipe included tinted water and a mixture of clear oil with translucent paraffin and tetrachloromethane.
In 1970, carbon tetrachloride was recognized as a toxic substance and removed from the composition, so the recipe had to be changed. Paraffin does not mix with water. Usually its density is much lower than the density of water, but the addition of carbon tetrachloride makes it a little heavier than H2O, causing it to sink to the bottom. The lamp housing is a transparent vessel with an incandescent lamp at the bottom.
Sinking down, the paraffin heats up from the lamp. Under conditions of increasing temperature, it expands faster than water, that is, it becomes less dense, which is why it rises up in the form of beautiful bubbles. Moving away from the lamp, the paraffin cools, and, as soon as they reach the top of the vessel, the bubbles again smoothly fall down.
A “kitchen” version of a lava lamp can be built in minutes. In it, the ingredients are interchanged: a transparent vessel fills the vegetable oil, and a denser colored water falls down. Water and oil, as you know, do not mix with each other.
To start the show, it is enough to throw a colorless effervescent tablet, for example, soluble vitamin C. Such tablets contain acidic substances, carbonates or bicarbonates, which, when reacted with water, emit carbon dioxide. Bubbles of gas rise through the oil, taking with them part of the tinted water. Along the way, the bubbles meet and combine into larger droplets. Having reached the top, the gas escapes into the air, and a water drop gradually drops down. It remains only to illuminate the vessel with a flashlight at the back or bottom.The article “Cold Lava” was published in the journal Popular Mechanics (No. 5, May 2013).