Aniline was accurately investigated by A. W. Hoffman in 1843. He was able to show that all of the above products are identical and for them he selected Fritsche's name, aniline. His work on the separation of aniline from coal tar started in 1843, and continued after his arrival in England in 1845, and it is remarkable to learn that practically all of them aniline used for his numerous researches was obtained by the laborious and costly process of distilling indigo with caustic potash. Having found aniline in coal tar he was persuaded that benzene could also be found in it. This belief was verified by Charles Mansfield who obtained both benzene and toluene from coal tar.