This week, we travel back to Roman times to mine a highly toxic compound. This is Simon Cotton:

Simon Cotton

Readers of the historical parody "1066 and All That" will know that the ancient Romans were a top nation because of their classical education. Some of their scientific knowledge is also accurate. They know how toxic mercury is. Mercury and some of its compounds have been known for over 2,000 years; the Romans mined cinnabar (mercuric sulfide) in Almaden, Spain. They sent criminals to work in mercury mines, which was considered a death sentence.

The Romans used cinnabar as an orange-red pigment and also baked it to obtain metallic mercury. Whether you inhale cinnabar dust or mercury vapor, the result is the same: mercury poisoning. In the ancient world, mercury was used to create amalgams with gold or silver, used in silver mirrors, gilded glass, or luminous letters in manuscripts. After applying the amalgam, simply allow the mercury to evaporate. Mercury compounds are used in medicine dimethylmercury , to treat syphilis (ineffective), and the metal is used in thermometers and barometers.
Many scientists fell victim to mercury poisoning, including Sir Isaac Newton, Michael Faraday and Blaise Pascal. Alchemists were interested in turning mercury into gold. King Charles II of England was an enthusiastic chemist who died suddenly in 1685 after inhaling mercury during experiments.

Mercury nitrate was used to preserve the felt used in hat making and to soften hair. As the felt dries, toxic dust forms. Workers absorbed mercury and developed symptoms such as Hatter's Shiver. The idea of the Mad Hatter in Alice in Wonderland is not an exaggeration of Lewis Carroll's idea, although the character described does not display any of the typical symptoms.
The most toxic mercury compounds are organometallic compounds containing mercury-carbon bonds. The first one was made in 1852; Sir Edward Frankland discovered that methylmercury iodide crystals formed if a mixture of methyl iodide and metallic mercury was exposed to sunlight. Many similar compounds followed. In the early 20th century, people began to use them as fungicides for seeds. They killed the fungi and they killed the humans. Some people make bread directly from grains instead of growing them; leading to an epidemic of mercury poisoning. In February 1971, warnings on bags of treated grain were ignored in Iraq because the warnings were in Spanish. Hundreds died. When a Japanese chemical company discharges mercury waste into the sea, anaerobic bacteria convert it into methylmercury, which is absorbed by plankton and passed to humans through fish along the food chain. As a result, thousands of people in Minamata Town were poisoned.