Few sights are as iconic as the menacing monolith of a woman draped in a long dress, overseeing a nearby busy metropolis that could just as well be the world’s capital. Nobody questions her choice of attire. Her dress’s bright, cyan-tinged greenness has become a brand on its own.
Walking along the ever-buzzing streets of the metropolis, one can find the iconic green silhouette crowned with a wreath of rays on fridge magnets, keychain pendants, posters, and stickers.
But the modern appearance of the Statue of Liberty, guarding the mouth of the Hudson River as it enters the Upper Bay, is far from how she was designed and imagined in the late nineteenth century. The green—as iconic as it is nowadays—was born from the boring dullness of dark metal plates of which the monument is made, slowly interacting with water and air. Some colors seem to abound in nature, providing hues to rocks, soil, stones, and gravel. In most cases, however, these are the less exciting brown, grey, and beige tones. On the other hand, green, quite similarly to other more brilliant and conspicuous colors like blue, red, or yellow, emerges reluctantly, usually harboring some specific metals’ color-producing powers.
Greenwashing the Green
Try to visualize a lush, dense forest pierced by the rays of the morning sun. Few images evoke the feeling of calmness and the sensation of connectivity with nature and the living world. Green is the color most commonly associated with life. The greenery of tree leaves of a tropical forest, with its canopy stretching to the edges of the horizon, is almost archetypically wild and alive. No wonder companies and institutions worldwide are so eager to use green when they want to make their connection with nature clear. The environmental identity attached to the color green is also why people sometimes attempt to greenwash products and ideas that are not perceived or regarded as environmentally friendly.
Yet green also has a darker, more malicious side to it. Nature seems able to produce it effortlessly, infusing tones of green plants’ tissues with the brilliant emerald pigment chlorophyll. Reproducing green for our selfish human desires is a different endeavor altogether. Historically, most dyes used as favorite greens by painters, tailors, architects, and artisans have been foul, treacherous substances. Even today, in the era of synthetic dyes and more sustainable chemistry, producing green involves rather unpleasant heavy metals and releases side products that are difficult to neutralize. The neon green Statue of Liberty has embedded one of such hues deep in modern pop culture.
In 1886, the pedestal designed to elevate the statue was finished. The monument itself, designed and crafted in France as a gift from the French to the Americans, had arrived in New York almost one year earlier. The gigantic sculpture was in pieces, carefully packed in huge crates, shipped aboard the warship Isère from Rouen in Normandy. Its reassembly took another six months. First, the builders had to erect a steel skeleton designed by Gustave Eiffel (the exact same Eiffel responsible for building the most recognizable landmark of Paris). Then, piece by piece, the copper “skin” of the statue was laid on the steel scaffolding.
Yes, copper. Liberty Enlightening the World was sculpted entirely in this fiery-red metal, typically encountered in wires and electronic circuits nowadays due to its exceptional electric conductance. One of the most iconic greens was absent from the statue’s overall appearance—for weeks after assembly, the monument shone with sharp metallic gloss, scattering pinkish-red sparkles all over the bay as the sun illuminated its uneven surfaces. During the following months and years, the copper shell tarnished, turning red, then brown, until it became almost black some three to four years after reconstruction. Then a slow process of turning bright green began, marked by a gradual yellowing of copper sheets reacting with air and atmospheric moisture. A dark layer of copper oxides and other complex compounds slowly turned brown-greenish, eventually developing its recognizable, green-bluish tinge twenty-five to thirty years after the statue’s skin was first exposed to the elements. Some people who witnessed the initial stages of its construction may have never had a chance to see it as we can today.
The current hue of the Statue of Liberty takes its bright greenness from verdigris—a mixture of copper salts and hydroxides produced when metallic copper comes in contact with water solutions of acids. The verdigris covering the Statue of Liberty is most likely composed of various forms of copper sulfate and copper carbonate mixed with varying amounts of hydroxides and polyhydroxides—such composition is mainly due to exposure to carbon dioxide from the air and sulfuric acid from acidified rainwaters (acid rain was a particularly prevalent environmental issue throughout the twentieth century). Also known as patina, verdigris can be seen everywhere on copper surfaces (e.g., copper-lined roofs, and bronze and brass monuments) that have remained under the influence of rain and air long enough.
Its electric, almost impossible, green hue did not go unnoticed by painters and artisans looking for new, exciting colors that could be reproduced on canvases and other works of art. Known already in antiquity, verdigris was one of the most commonly used green pigments. Its production was almost trivial. In the Middle Ages, the most widely used method involved mixing strips of copper with pieces of wood infused with vinegar and then burying large blocks of the mixture in horse or cow dung. Weeks or months later, they were dug up, and verdigris that had accumulated on the surface of metal pieces was scraped off and powdered. An alternative, dung-free recipe gained popularity in the eighteenth century: copper plates were packed into large ceramic jars filled with wine. Acids present in wine and acetic acid produced during oxidation of wine reacted with metal, making the acetate-dominated form of verdigris.
Benign and user-friendly as these concoctions may seem, we should not be fooled by their apparent, almost culinary gentleness. Copper is a heavy metal that is pretty toxic, especially if ingested or absorbed in soluble form. Over time, those working with verdigris production eventually tended to develop more or less severe symptoms of copper intoxication, leading to coma and death in the most extreme cases. Notwithstanding its modern eco-friendliness and ubiquitous application in virtually all nature-related contexts, green was one of the most toxic and environmentally unfriendly pigments. And almost as if artists had to be punished for its widespread use—the verdigris green was quite unstable, slowly turning into brownish-green and then into a murky, hard-to-classify shade typical for dirty puddles. In search of a better, more resistant green, chemists embarked on a long journey infused with solutions of all sorts of metals with varying degrees of toxicity, looking for the right combination of elements to yield the ultimate greenness. In a way, they succeeded. Unfortunately, the “green” technological revolution soon claimed even more lives . . . including one famous emperor.
Insectophobes’ Favorite Décor
The end of the eighteenth and the beginning of the nineteenth century saw a real revolution in how living spaces were decorated and furnished. The fast-developing chemical industry kept introducing new synthetic compounds, including dyes and pigments meant to supersede their less permanent, natural analogues, which were often very costly or cumbersome to obtain. Soon, the living rooms and libraries of the wealthier middle class received their all-new color treatments, with wallpapers featuring floral and animal motifs printed in vibrant blues, purples, and greens. The latter was especially desired: at last, rooms could be decorated in lush, bright greens, bringing the images of fresh foliage and peaceful forest paths. Enthusiasts of such décor quickly noticed that one particular color—Scheele’s green, also known as Schloss green—tended to provide additional benefits. Rooms decorated with wallpapers prepared with this pigment were apparently more resistant to insect infestations. Even mosquitos seemed to stay away from such green interiors! The pigment, synthesized in 1775 by Carl Wilhelm Scheele, became an instant bestseller due to its cheapness and ease of production.
Scheele’s green did not escape the copper dependence of green dyes. Chemically, it is acidic copper arsenite (CuHAsO3 in the secret dialect of chemistry’s sorcerers), a crystalline emerald powder. It is closely related to another pigment: Paris green, or copper acetate triarsenite. Beautiful and hypnotizing at first, those colorful masterpieces of chemical synthesis were even more sinister than their old, distant cousin verdigris. Apart from copper, they also contained another extremely noxious element: arsenic. Once absorbed into a living organism, arsenic disrupts critical stages of cellular respiration and gradually damages the nervous system, liver, kidneys, heart, and spleen. The havoc wreaked by arsenic is irreversible: the body and mind slowly shut down and disintegrate. Scheele himself most likely fell victim to the mangling effects of this element (and other heavy metals used in his laboratory on a daily basis)—he died in 1786, aged forty-three, suffering from severe kidney and neurological problems.
Unfortunately, people were long unaware of the toxicity of many arsenic compounds. Green pigments containing it were long regarded as safe, even though people working in factories producing them often exhibited severe poisoning symptoms. Similarly, nobody linked “green fingers”—a widespread affliction of Victorian seamstresses responsible for fixing their female employers’ (often emerald-green) dresses—and the chemical nature of dyes used to produce the fabrics’ extraordinary coloration. Those obsessed with vibrantly green wallpapers and fabrics were utterly oblivious to the ease with which copper arsenates release volatile arsenic compounds when exposed to moisture. The bug-repelling properties of green wallpapers were neither magic nor due to some unknown averseness of insects towards certain shades of green. Invertebrates are extremely sensitive to arsenic, and, like the proverbial canary in a coal mine, their disappearance indicated the presence of a deadly toxin. Actually, “Paris Green” was named after the capital of France due to its widespread use as rat poison in Parisian sewers. Keeping up with the latest trends does sometimes require sacrifices. Still, it is doubtful that anyone would go as far as covering their walls with substantial doses of potent pesticide, irrespective of what brilliant color it may have.
The Emperor’s (Bedroom’s) New Clothes
Napoleon Bonaparte, also known since his coronation as Napoleon I, Emperor of the French, died in 1821, not so long after the beginning of the eighteenth century, with all its colorful technological inventions. His demise was untimely—he was only fifty-one, and, although he had been spending the last years of his life in exile on the British island of Saint Helena, his life was not in direct danger. Napoleon himself was, of course, convinced of covert conspiracies to assassinate him. A few weeks before death, he wrote in his will: “My death is premature. I have been assassinated by the English oligopoly and their hired murderer . . .” Clearly, the paranoid fear of murderers lurking behind every corner, commonly attributed to many fallen rulers, did not spare Napoleon.
However, potential assassins would have to bypass a garrison of twenty-one hundred soldiers initially guarding the prisoner, not to mention sail to the remote island in the middle of the Atlantic. Historians have provided several hypotheses about what caused the emperor’s departure, some bolder, others relatively mundane. Setting aside any (hard to prove) speculations about assassination attempts, one explanation has gained particular attention. Forensic evidence and illegally collected scraps of old wallpapers suggest that Napoleon’s end had nothing to do with the treacherous plots of his enemies. The blame was instead on damp, tropical weather, ill-considered choice of interior décor, and the latest inventions of industrial chemistry.
The first clues came from chemical assays performed on samples of hair belonging to Napoleon and his closest relatives. They all exhibited shockingly elevated levels of one particular element: arsenic. Liver problems and bloody vomiting noted by Napoleon’s medics shortly before his death seem to corroborate the arsenic poisoning hypothesis. In its final weeks, the emperor’s body was literally loaded with substances from all corners of the periodic table of elements as doctors tried to stabilize his deteriorating health by administering questionable medicines based on antimony, mercury, and hydrocyanic acid (today, all known to be very efficient poisons). However, it was arsenic that had likely initiated the slow deterioration of Napoleon’s body. Its source? Ornamented wallpapers covering most of his last home’s walls, many bearing Scheele’s emerald pigment’s vibrant, leafy-green hue. In the extremely damp, tropical air, copper arsenite quickly decomposed, releasing large amounts of volatile arsenic compounds.
The final verdict was confirmed when a woman from Norfolk in England found a rather unusual piece of paper in an old family-owned scrapbook, labelled with a handwritten note that identified it as a small piece of wallpaper taken from a dining room in Napoleon’s last home on Saint Helena. Having heard of the toxic legacy of green Victorian wallpapers, she asked a chemist, David Jones, to analyze it. The small, century-old piece of paper contained ten times more arsenic than the safe maximum level. One of the greatest conquerors in history, an icon of European history, was killed by a particular shade of green—the same color that, ironically, serves today as a symbol of hope, wild nature’s beauty, and many of our collective actions aimed at preserving it.
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