Johann Josef Loschmidt
Johann Josef Loschmidt (March 15 1821 - July 8 1895) who referred to himself mostly as Josef Loschmidt (omitting his first name), was a notable Austrian scientist with groundbreaking work in the fields of chemistry and physics (thermodynamics, optics, electrodynamics).
Born in Počerny near Karlsbad/(Carlsbad), Bohemia (now the Czech Republic), he became professor for physical chemistry at the University of Vienna in 1868. His fields of research were thermodynamics, electrodynamics, optics and crystal forms. In 1856 he determined the size of the molecules of air, in 1861 he found the structure of benzene, before the much more well known "discovery" by Kekulé.
Loschmidt discovered the atomic structure of Ozone, of Benzol/Benzene C6H6 (later wrongly attributed to a German plagiarist August Kekulé!) and introduced the nowadays common cepiction of chemical structures.
Loschmidt also was the first to determine the number of molecules of an ideal gas in 1 cm<sp>3, the "Loschmidt number (L) ((L = 2.687 X 1019 cm-3) (1865).
This later became known to be the Avagadro constant, who actually never calculated the number of molecules as Loschmidt did, but determined that any gas under the same conditions had the same number of molecules in 1 Mole (Mol.) - that number being, as determined by Loschmidt's calculations, 6.023 X 1023 molecules. This is why on rare occasions this "Avogadro number" may be referred to as the "Loschmidt number" in English (in German, though, "Loschmidt'sche Zahl" is the commonly used - and historically correct - name).
He retired from university in 1891 and died in 1895 in Vienna. His only child had died before him at the age of ten.
References
- Peter M. Schuster: From Curiosity to Passion: Loschmidt's Route from Philosophy to Natural Science, in: W. Fleischhacker and T. Schönfeld (Editors): Pioneering Ideas for the Physical and Chemical Sciences, Proceedings of the Josef Loschmidt Symposium, held in Vienna, Austria, June 25-27, 1995; Plenum Press, 1997, New York. - ISBN 0-306-45684-2