However, these hopes were disappointed, and in 1855, after refusing the offer of a chair of chemistry at the new Zürich Polytechnic in 1854, he accepted the professorships of chemistry at the Faculty of Sciences and the École Polytechnique at Strassburg, where he died the following year, having just completed checking the proofs for "Traité de chimie organique" (4 vols., Paris, 1853–56), his magnum opus.