LAVA LAMPS ARE BACK FROM THE 60's!!
ViV has a treasured find!! It's a lovely fushia pink and purple!
Briton Edward Craven-Walker invented the lava lamp in 1960. The lamp contains a standard incandescent bulb or halogen lamp which heats a tall (often tapered) glass bottle containing water (often with glycerol derived additive) and a transparent, translucent or opaque mix of wax and carbon tetrachloride (although other combinations may be used). The wax is slightly more dense than water at room temperature but is less dense under warmer conditions. This occurs because wax expands more than water when both are heated. When heated, the wax becomes fluid, its relative density decreases, and blobs of wax ascend to the top of the device where they cool (which increases their density relative to that of the water's) and then 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. The underlying mechanism is a form of Rayleigh-Taylor instability. The bulb is normally about 25 to 40 watts. It may take 45 to 60 minutes for the wax to warm up enough to freely form rising blobs (depending on the original temperature). It may take 2 to 3 hours if it has been in a cold room for a long time.
Once the wax is molten the lamp should not be shaken or knocked over or the two fluids may emulsify and the wax/blobs will remain cloudy rather than clear. Some recombination will occur as part of the normal cycle of the lava in the container but the only means to recombine all of 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.
from Wikipedia
