Emerald green (Paris green, Schweinfurt green) was the most brilliant green of the 19th century — and one of the most lethal. An arsenic-copper compound, it was used in wallpaper, paint, and even food colouring, causing numerous deaths.

Emerald green is historically the colour of beautiful danger — brilliant, desirable, and deadly. It represents the 19th century's uneasy relationship with chemical progress: new wonders that came with undisclosed costs.

Napoleon Bonaparte may have died from arsenic poisoning from emerald green wallpaper in his St Helena bedroom — hair samples show elevated arsenic. The Victorian era's fashion for vivid green fabrics and wallpapers led to widespread chronic arsenic poisoning. Cézanne used it and suffered health problems attributed to pigment exposure.