Aureolin

Aureolin (sometimes called Cobalt Yellow) is a pigment sparingly used in oil and watercolor painting. Its color index name is PY40 (40th entry on list of yellow pigments). It was first made in 1848 by Nikolaus Wolfgang Fischer in Breslau and its chemical composition is potassium cobaltinitrite. The investigation by Gates gives the exact modern procedures for the preparation of aureolin and also the methods for its identification in paintings.