Dicyanin (synthetic dye)

Dicyanin is a synthetic blue dye derived from coal tar that was used for sensitizing photographic plates, first manufactured in the early twentieth century by the Dye Works of Meister, Lucius, and Brüning at Höchst (near Frankfurt), Germany. It became associated with auric research thanks to the experiments of Walter J. Kilner, who used the dye in the manufacture of his Kilner screens.