 Rubiacine was identical to nordamnacanthal (1,3–dihydroxyanthraquinone–2–aldehyde) and rubianine was an unusual C–glucoside of unknown constitution.In 1855, Schunck turned his attention to the subject of indigo, preferring the name indigo-blue to the alternative name, Indigotine.He grew woad from "good French woad seed", extracted the dye precursor with cold ethanol and after further processing obtained a brown syrup which he called "indican".