It is easy to see why mercury holds such fascination. It is the only metal to be liquid at room temperature. It is also one of the few things that reacts with that most alluring of all the elements: gold.
The process is extraordinary to see.
In his laboratory at University College London, chemistry professor Andrea nike running shoes Sella peels off a fragile leaf of gold and places it on a shimmering ball of mercury.
Before my eyes the gold gradually vanishes, folding itself around the silver blob like bed sheets, before dissolving away.
It is mercury’s unique relationship with gold that fascinated the alchemists.
“Mercury is a profound, systemic and long-term poison for humans, but also for other organisms,” says Sella.
“So getting mercury into the environment is a very serious issue.”
About half the mercury that enters the environment every year comes from volcanic eruptions nike free run 3 and other geological processes. There is nothing we can do about it.
But the other half is released by mankind.
Mercury’s bright red ore, cinnabar, has been employed as a pigment since Neolithic times. Some 10,000 years ago, the earliest artists used it to daub pictures of aurochs, the now extinct giant wild cattle they hunted, on the walls of caves in Turkey.
The Romans used it as a form of rouge make-up, and the Chinese to colour their lacquer, while in the Middle Ages the pigment was mixed with wax to provide the seals placed on formal documents.
For centuries the metal was also used in medicine. Even fairly recently it was still used in antiseptics, laxatives, anti-depressants, and drugs to combat syphilis.
Most adults will have used mercury thermometers, and many of us still have mercury amalgam fillings in our teeth.
Some of the mercury in those medicines and tooth fillings will eventually find its way into shop nike the atmosphere. Many of us can expect to be cremated, that means any mercury goes up in smoke along with our bodily remains.
And tiny amounts of mercury vapour are the light source in fluorescent bulbs – that’s why they need to be disposed of very carefully.