The curious case of Scheele’s Green

In chromotherapy, green is the colour of the harmony, the peace and the nature. Wearing, using or be immersed in this colour should nurture a deep state of calm. What would happen if, instead, it provoked a state of “eternal peace”? What if the abuse of the green colour would lead to the six-feet-under-peace?

During the XIX century, the risk of death due to the use of the green colour was not so rare, especially since the love for the Scheele’s green overflowed. This specific shade of green took the name from the Swedish chemist Carl Wilhelm Scheele, the first who synthetized it in 1775; this story explains also why Scheele’s green is sometimes called Swedish green. From a chemical point of view, the compound is an acid copper arsenite with a complex chemical formula, due to the variable presence of copper and arsenic oxides. The formula could be simplified and expressed as CuHAsO3. The particles obtained during the compound synthesization are medium size and they form together an amorphous material that sometimes can show crystalized phases.

In the field of Fine Arts, Scheele’s green is a not so loved and not used: the artists of XVII and XIX Centuries did not really appreciated its dirty shade. Turner probably used this colour in a painting of 1805, named Guildford from the Banks of the Wey, and perhaps it was present in Manet’s palette during the painting of La Musique aux Tuileries in 1862. In a short while, emerald green rapidly substituted the Scheele’s hue.

Looking at the Scheele’s formula, it is easy to understand the toxicity and the danger of this colour due to the presence of arsenic. Nevertheless, in the XIX century it was a low-cost product sold for several uses: inks, varnishes, dyes for fabric and for toys. In addition, the arsenical green was used as insecticide: who would have thought it!? For all these applications Parker patented a green pigment called Patent green, in 1812.

The Scheele’s green was also adopted in the wallpaper of a house on St. Helena Island, in the South Atlantic Ocean, where Napoleon Bonaparte served his exile. In XX Century a group of scientists realized some analysis on Napoleon’s hair and discovered the presence of arsenic. Indeed, some species of fungi can metabolize arsenic, eliminating it as toxic gases. Moreover, these fungi can grow on the wallpaper glue, using it as culture medium. Therefore, probably Napoleon die was due to the poisoning and not to an ulcer. However, Clemenza et al. in 2008 analysed again the hair of Napoleon and of their relatives, discovering that the Emperor probably touched with the arsenic (and perhaps the poisoned green) since an early age. So, the toxic wallpaper was not the only one responsible for Napoleon death.

A little treat: do you remember the colour of the venom used by the Evil Queen Grimhilde to poison Snow White, in the 1937 Walt Disney Pictures’? Yes: it was GREEN!

Melania

References

- Bevilacqua, Borgioli, Adrover Garcia “I pigmenti nell’arte. Dalla preistoria alla rivoluzione industriale”. Ed. Il prato, 2010

- Clemenza, M., et al. "Misure con attivazione neutronica sulla presenza di arsenico nei capelli di Napoleone Bonaparte e di suoi famigliari." Il Nuovo Saggiatore 24.1-2 (2008): 19-30.

- Ball P., “Colore. Una biografia”. Ed. Bur, 2001

- “Occhio nucleare sui capelli di Napoleone”. On the newspaper “Il sole 24Ore”, published 11/02/2008