The chemist who created the deadly blue color killed many people

Carl Wilhelm Scheele was born in 1742 in Stralsund, in present-day Germany. His father was a famous businessman, but Scheele chose to study chemistry. At age 14, Scheele worked with a pharmacist in Gothenburg, Sweden, where he had his first direct experience with chemicals. The wide variety of chemicals available interested him and he often experimented with them late into the night after work. One evening, while experimenting with a particularly volatile mixture, Scheele caused a huge explosion that shook the whole house and made his boss angry. Scheele was asked to quit his job and not long after, he found a better position with a new employer, CM Kjellström in Malmö. Through him, Scheele first came into contact with academia. Two years later, in 1967, Scheele moved to Stockholm and worked as a pharmacist.

One of his first discoveries was tartaric acid, a white crystalline organic acid that exists naturally in many fruits such as grapes. Grape producers have known tartaric acid for centuries, but Scheele developed a technique to chemically separate it. Scheele was also the first to isolate lactic acid from yogurt, as well as glycerin. He discovered hydrogen fluoride and hydrogen sulfide. But Scheele’s greatest discovery was oxygen, and this event also marked the beginning of his extremely unlucky career.

Scheele’s discovery of oxygen was born 3 years before Joseph Priestley but it took him 6 years to publish his research. Before then, Joseph Priestley had published experimental data and conclusions about oxygen. Before this gas was named “oxygen”, Scheele called it “fire gas” due to its ability to aid combustion. Scheele also found that the air was a mixture of “fiery air” and other gases that were/were not breathable.

Scheele went on to discover at least six more elements, barium, chlorine, molybdenum, manganese, nitrogen, and tungsten, but these were not recorded. In the case of chlorine, Scheele suggests that this is an oxide collected from hydrochloric acid. It was only four decades later that Humphrey Davy was certain this was an element. Davy named it chlorine. As for barium, Scheele knew it was an element but could not isolate it. It was Humphrey Davy who successfully isolated the metal.

Scheele will likely be remembered for many things and forgotten for his only invention that attracted attention, a compound called Scheele Blue that killed countless people over the decades, possibly including including Napoleon. Scheele blue is a green-yellow pigment used to dye paper such as wallpaper, cotton, linen and even in some children’s toys. This colorant is a compound of arsenic.

At that time, the toxicity of arsenic was unknown. People use bright green wallpaper in their rooms, women wear green dresses, and newspapers also use green color to print advertisements. During Napoleon’s exile on the island of Helena, he lived in a house with rooms painted green, his favorite color. Although Napoleon died from stomach cancer, exposure to arsenic increases the risk of carcinoma.

In many ways, Scheele was far ahead of his time. He discovered more elements and isolated more compounds than any of his colleagues, but the only thing named after him was a poison. Years of working with dangerous chemicals, including heavy metals (Scheele had a habit of smelling and tasting any chemicals he discovered) took a toll on his health, and he developed kidney disease. Scheele died quite young at the age of 43 from mercury poisoning.