the world > matter > colour > named colours > blue or blueness > blue substances > [noun] > others (3)
A dark blue colouring matter obtained by Reichenbach as a high-boiling fraction in the fractional distillation of wood-tar.
a blue or bluish-green substance obtained by reacting chlorophyll with hydrochloric acid.
A deep blue substance contained in many essential oils, also called azulene.