Metallica's song about the Yves Klein Blue pigment brought to mind Schweinfurt Green – a pigment beloved by Turner, Monet, Renoir, Gauguin and Cézanne. And the next time you see Van Gogh, think of two chemists, Russ and Sattler, working at the Wilhelm Dye and White Lead Company in Schweinfurt in 1814 who combined copper, acetate and arsenic to make a pigment that was in use until the invention of cobalt green. Use of Schweinfurt Green extended well beyond the art world – the high arsenic content made it effective against rats in the sewers of Paris (the pigment is also known as Paris Green) and farmers in the mid-west sprayed it on the Colorado potato beetle, and tobacco growers on the budworm.
Speech bubble: "Curses! It's plain to see malaria mosquitoes we'll never be!"
In Michigan, in 1874, Dr Robert Kedzie published what is now one of the rarest books in the world - Shadows from the Walls of Death: Facts and Inferences Prefacing a Book of Specimens of Arsenical Wall Papers. His text warned of arsenic poisoning, which was fine, but he bound into the book eighty-six sheets of wallpaper printed with Schweinfurt Green. The book is so dangerous that only four copies remain in existence. But despite Dr Kedzie's warnings, the compound became an insecticide of choice worldwide and as late as the 1940s was being sprayed on malarial marshes. The Schweinfurt chemists' pigment was not an invention - rather, it was a development from an earlier pigment made by Carl Wilhelm Scheele in 1775. Though born in Sweden, Scheele learned his pharmacy in Gottingen. Isaac Asimov was to describe him as 'hard-luck Scheele' and with reason. Tardiness in publishing his findings meant he was never credited during his lifetime with his discoveries of molybdenum, tungsten, barium, hydrogen, dephlogisticated muriatic acid (Humphry Davy published first with the name 'chlorine'), uric acid, lactic acid, citric acid – and many other substances, including 'fire air' (Joseph Priestley published first and Lavoisier named it oxygen). Sheele also invented a process for mass-producing phosphorus which made Sweden, which has a lot of trees, a world leader in the production of matches.
A plate from Scheele's Physische und Chemische Werke (1793) (c) Christie's
Unfortunately, Scheele's science did not extend to understanding the damage his Green would do when released into the world. There are nineteenth century accounts of children sickening in bright green rooms, of ladies in green dresses fainting and a famous Christmas party lit by green candles where all fell ill. Scheele's pigment was also used as a food dye for products such as blancmange. This particular pudding was, apparently, a great favourite of the citizens of Greenock - and the consequent illnesses and deaths have to this day created a prejudice in Scotland against green sweets. Napoleon was not a lover of blancmange but this did not save him. Exiled to St Helena, he cheered himself up by painting all the rooms in his house bright green, his favourite colour. St Helena is a damp island and mould grows and Napoleon appears to have spent his days breathing in arsenic laden fungal spores; certainly, a surviving lock of hair shows traces of arsenic sufficient to suggest that its carcinogenic properties triggered the cancer that killed him. And then there was the fate of poor bad-luck Scheele, for whom I have enormous sympathy. On my twelfth birthday, my parents gave me a Junior Chemistry Set, you may have had one, packed with what ought to have been totally harmless powders – unless you knew the pharmacist in town who was happy to sell a twelve year old chemical-enthusiast glass bottles of concentrated sulphuric and hydrochloric acids. My bicycle then, a Cinelli of great beauty, had a double water bottle holder on the handlebars and I would cycle home looking down fondly at the glass stoppers holding in these completely lethal liquids. My chemistry set had a great deal of apparently useless copper sulphate – but if you mix it with hydrochloric acid, you get chlorine gas. So I did. I bubbled some chlorine up into a test tube and wondering what I had made, sniffed and fell to the floor, my lungs in a burning agony. This is why I have sympathy for Scheele, who lived in the age of taste-and-sniff chemistry. He spent his days with arsenic, lead, hydrofluoric acid (which he discovered) and other serious toxins – and died of mercury poisoning at the age of 43. Monday sees the Race Marshal's birthday, so we shall spend a few days in this surprising city of Schweinfurt. Tomorrow we seek out the man whose poetry inspired some of the greatest music in the world. Tonight, given it is still Spargelzeit, we are booked into Ross Stuben, an Italian bistro offering grilled 'white gold' with tagliatelle in a cream and balsamic sauce. Usually, we celebrate the Race Marshal's birthday in the Vale of Evesham where they have black asparagus from New Zealand but this will do.
Here is French chef Hélène Darroze, in the Vogue Kitchen in Paris, ruining white asparagus with pickles and lemon - https://youtu.be/OqsH33--Ehg
This is the song that Scheele's name kept triggering -https://youtu.be/OMAIsqvTh7g
A little film about Scheele's Green (though one viewer has commented: "I was somewhat unnerved by how joyfully you described someone being poisoned to death") - https://youtu.be/ypxKCJS52G8
TED Ed have made this film about the world's deadliest colours - https://youtu.be/gKfjHTk8KrY
And this R&B group opted to call themselves Paris Green instead of the more echt Schweinfurt Green. Here they sing about Parchman Farm, a maximum security prison in Mississippi - https://youtu.be/UlyIFwseuOk