Which poisonous chemical compund was named after the Greek for blue, having been first identified during the production of the dye 'Prussian Blue' in the early 18th century ?
Prussian blue was eventually given the name "Blausäure" (literally "blue acid") because of its derivation from Prussian blue, and in English became known popularly as Prussic acid. Cyanide, a colorless anion that forms in the process of making Prussian blue, derives its name from the Greek word for dark blue. From the beginning of the 18th century, Prussian blue was the predominant uniform coat color worn by the infantry and artillery regiments of the Prussian Army. As "Dunkelblau" (dark blue), this shade achieved a symbolic importance and continued to be worn by German soldiers for ceremonial and off-duty occasions until the outbreak
Prussian blue made from lapis lazuli. Japanese painters and woodblock print artists, likewise, did not have access to a long-lasting blue pigment until they began to import Prussian blue from Europe. Prussian blue (also () · "x") was probably synthesized for the first time by the paint maker Diesbach in Berlin around 1706. Most historical sources do not mention a first name of Diesbach. Only Berger refers to him as Johann Jacob Diesbach. The pigment is believed to have been accidentally created when Diesbach used potash tainted with blood to create some red cochineal dye. The original dye required potash, iron sulfate,