Fuchsine (sometimes spelled fuchsin) or rosaniline hydrochloride is a magenta dye with chemical formula C20H19N3·HCl. There are other similar chemical formulations of products sold as fuchsine, and several dozen other synonyms of this molecule. It becomes magenta when dissolved in water; as a solid, it forms dark green crystals. As well as dying textiles, fuchsine is used to stain bacteria and sometimes as a disinfectant. In the literature of biological stains the name of this dye is frequently misspelled, with omission of the terminal -e, which indicates an amine. American and English dictionaries (Webster's, Oxford, Chambers, etc.) give the correct spelling, which is also used in the literature of industrial dyeing. It is well established that production of fuchsine results in development of bladder cancers by production workers. Production of magenta is listed as a circumstance known to result in cancer. History Fuchsine was first created by Jakub Natanson in 1856 from aniline and 1,2-Dichloroethane. In 1858 August Wilhelm von Hofmann obtained it from aniline and carbon tetrachloride. discovered the substance independently of Hofmann the same year and patented it. Fuchsine was named by its original manufacturer Renard frères et Franc, is usually cited with one of two etymologies: from the color of the flowers of the plant genus Fuchsia, named in honor of botanist Leonhart Fuchs, or as the German translation Fuchs of the French name Renard, which means fox. An 1861 article in Répertoire de Pharmacie said that the name was chosen for both reasons. Acid fuchsine Acid fuchsine is a mixture of homologues of basic fuchsine, modified by addition of sulfonic groups. While this yields twelve possible isomers, all of them are satisfactory despite slight differences in their properties. Basic fuchsine Basic fuchsine is a mixture of rosaniline, pararosaniline, new fuchsine and Magenta II. Formulations usable for making of Schiff reagent must have high content of pararosanilin. The actual composition of basic fuchsine tends to somewhat vary by vendor and batch, making the batches differently suitable for different purposes. In solution with phenol (also called carbolic acid) as an accentuator it is called carbol fuchsin and is used for the Ziehl–Neelsen and other similar acid-fast staining of the mycobacteria which cause tuberculosis, leprosy etc. Basic fuchsine is widely used in biology to stain the nucleus, and is also a component of Lactofuchsin, used for Lactofuchsin mounting. Properties The crystals pictured at the right are of basic fuchsine,