Candles are one of the oldest forms of generating light.聽Any flame, of course, is a source of light so candles emerged from a search for materials that could burn for a long time.聽Nobody knows who first noted that beeswax, beef tallow or spermaceti from whales burned well, but it would not have been a difficult thing to notice.聽Countless people must have observed that the fatty parts of animals when cooked would sometimes catch fire.
Until the early part of the 19th century, candles were made by covering wicks with beeswax, tallow or spermaceti, but as the chemical industry got going, stearic acid became more and more available.聽This acid is formed when animal fats are broken down by the action of an alkali, such as sodium hydroxide.聽The stuff that forms in this reaction, sodium stearate, is soap.聽When sodium stearate is treated with an acid we get stearic acid.聽It turned out that stearic acid burned well and could be produced cheaply.聽It was great for candles, except for one thing.聽It was brittle.聽This problem was solved by adding some paraffin, a mixture of long hydrocarbon molecules, which was isolated from petroleum.
Now the problem was that the paraffin made the candle wax melt more easily and聽the wax would drip down the side to make聽鈥渨axicles.鈥澛燭o make a dripless candle, the wax has to have a high enough melting point so that the heat of the candle is not enough to melt the edges.聽How do you do this?聽By increasing the amount of stearic acid.聽Of course, you can just design a candle so that the edges are far from the flame. A big candle will not drip.聽The thicker the candle, the less likely that the flame will melt the edges.
But here's another little trick to making dripless candles.聽Pour some water into a bowl and add a couple of tablespoons of salt.聽Soak ordinary candles for a couple of hours and presto, you鈥檒l have dripless candles. How? Because the salt absorbs聽into the wax which in turn raises its melting point.聽But if you want a really interesting candle, you鈥檒l have to get hold of a dried stormy petrel.聽That鈥檚 a bird that lives in the Shetland Islands and has a very high-fat content.聽Islanders have by threading a wick through its beak and fixing its feet in clay and then burning the bird.聽But I bet the bird drips.
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