1911 Encyclopædia Britannica/Wislicenus, Johannes
WISLICENUS, JOHANNES (1835-1002), German chemist, was born on the 24th of June 1835 at Klein-Eichstedt, in Thuringia. In 1853 he entered Halle University, but in a few months emigrated to America with his father. For a time he acted as assistant to Professor E. N. Horsford at Harvard, and in 1855 was appointed lecturer at the Mechanics' Institute in New York. Returning to Europe in 1856, he continued his studies at Zurich University, where nine years later he became professor of chemistry. This post he held till 1872. He then succeeded A. F. L. Strecker in the chair of chemistry at Wiirzburg, and in 18S5, on the death of A. W. H. Kolbe, was appointed to the same professorship at Leipzig, where he died on the 6th of December 1902. As an original investigator he devoted himself almost exclusively to organic chemistry, and especially to stereochemistry. His work on the lactic acids cleared up many difficulties concerning the combination of acid and alcoholic properties in oxy-acids in general, and resulted in the discovery of two substances differing in physical properties though possessing a structure of proved chemical identity. To this phenomenon, then noticed for the first time, he gave the name of " geometrical isomerism." So far back as 1869, before the publication of the doctrine of J. H. van't Hoff and J. A. Le Bel, he expressed the opinion that the ordinary constitutional formulae did not afford an adequate explanation of certain carbon compounds, and suggested that account must be taken of the verschiedeneLagerung ihrer Atome im Raume. Later (see Die räumliche Attordnung der A tome in organischen Molekülcn, 1887) he extended the application of the van't Hoff-Le Bel theory, believing that it, together with the supposition that there are "specially directed forces, the affinity-energies," which determine the relative position of atoms in the molecule, afforded a method by which the spatial arrangement of atoms in particular cases may be ascertained by experiment. Wislicenus is also known for his work on aceto-acetic ester and its application as a synthetical agent. He was awarded the Davy medal by the Royal Society in 1898.