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, ferric sulfate, and dried cochineal. Instead, the blood, potash, and iron sulfate reacted to create a compound known as iron ferrocyanide, which, unlike the desired red pigment, has a very distinct blue hue. It was named and in 1709 by its first trader.