A nuclear staining solution containing, hematoxylin, ferric chloride and hydrochloric acid used in many non-routine techniques (special stains) because, it resists decolorization in acidic staining solutions. Ferric Chloride is a strong oxidizer, so it serves both as a mordant and oxidizer for Weigert's Hematoxylin.
Lidbury, J. A. et al. Interobserver Agreement Using Histological Scoring of the Canine Liver. Journal of Veterinary Internal Medicine. In Press, (2017). doi:10.1111/jvim.14684