Johann Josef Loschmidt (March 15 1821 - July 8 1895) was an Austrian physicist and chemist.

Born in Počerny near Carlsbad (today in the Karlovy Vary Region of 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. In 1865 Loschmidt first calculated the Avogadro's number (now called Avogadro's constant, which in the German language countries is still sometimes referred to as the Loschmidt number (now Loschmidt constant has another meaning).

He retired from university in 1891 and died in 1895 in Vienna.

External links

• http://www.physicstoday.org/pt/vol-54/iss-3/p45.html
• http://scienceweek.com/2004/rmps-15.htm
• http://www.uh.edu/engines/epi1858.htm