Shapes to Come

At a time when chemists knew little of molecular structure, a Viennese high-school teacher self-published a book that contained some of the earliest structural formulas.

In 1861 Viennese high-school teacher Johan Josef Loschmidt self-published a booklet titled Chemische Studien, in which he included two-dimensional representations of over 380 molecules. His use of double lines to denote double bonds and triple lines for triple bonds, easily recognizable to modern-day chemists, is considered the first such use in graphic formulas.

Throughout his life Loschmidt remained outside the academic chemical mainstream, and today he is better known by physicists. Born in Počerny in 1821 in what is now the Czech Republic, Loschmidt studied chemistry, physics, and mathematics. He pursued broad research interests, including the structure of carbon bonding, crystal structure, and the size of gas molecules. Shapes and numbers of molecules fascinated Loschmidt, and he is credited with the first computation of Avogadro’s number. In 1866 he became professor of physical chemistry at the University of Vienna.

Not all of Loschmidt’s structural formulas in Chemische Studien proved accurate. And in some cases, despite his accuracy, his intent is not entirely clear in terms of molecular shape and orientation. But in an age when the physical existence of atoms was still in question, his attempts—and his successes—remain remarkable.

The papers of Loschmidt, recently donated to CHF by a private collector, offer scholars a unique opportunity to explore the career and scientific contributions of this little-studied figure. In addition to a copy of Chemische Studien, the collection contains correspondence and research notes that explore numerous scientific and political topics, including batteries, electricity, magnetism, optics, thermodynamics, agriculture, economics, and “flight engines.”