In his early work as a chemist, he resolved a problem concerning the nature of tartaric acid. A solution of this compound derived from living things rotated the plane of polarization if light passing through it. The mystery was that tartaric acid derived by chemical synthesis had no such effect, even though its chemical reactions were identical and its elemental composition was the same. This was the first time that anyone had demonstrated chiral molecules. Pasteur's thesis on crystallography caught the attention of W.T. Fuillet, who eventually helped Pasteur obtain a position as a professor of chemistry at the College of Strasbourg. In 1854, he was named Dean of the new Faculty of Sciences in Lille. In 1856, he was made administrator and director of scientific studies of the Ecole Normale Superieure.