- Johann Josef Loschmidt
Infobox_Scientist
name = Johann Josef Loschmidt
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caption = Johann Josef Loschmidt
birth_date =March 15 1821
birth_place = Počerny (Putschirn, now part ofKarlovy Vary ,Czech Republic )
death_date =July 8 1895
death_place =Vienna ,Austria
residence =
nationality = Austrian
field =chemistry ,physics
work_institution =
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footnotes =Jan or Johann Josef Loschmidt (
March 15 1821 -July 8 1895 ), who referred to himself mostly as 'Josef' (omitting his first name), was a notableAustria n scientist who performed groundbreaking work inchemistry ,physics (thermodynamics ,optics ,electrodynamics ), andcrystal forms.Born of poor
Bohemia n farming stock in Počerny (Putschirn), now part ofKarlovy Vary ,Czech Republic , Loschmidt became professor ofphysical chemistry at theUniversity of Vienna in 1868.He had two early mentors. The first was a Bohemian priest,
Adalbert Czech , who persuaded Loschmidt's parents to send young Josef to high school in thePiarist monastery inSchlackenwerth and, in 1837, to advanced high-school classes inPrague .This was followed by two years of philosophy and mathematics at Prague's
Charles University , where Loschmidt met his second important mentor. This was the philosophy professorFranz S. Exner , whose eyesight was failing, and who asked Loschmidt to be his personal reader. Exner was known for his innovative school reforms, which included promoting mathematics and science as important subjects. He suggested to Loschmidt, who became a close personal friend, that he apply mathematics to psychological phenomena. In the process of doing this, he became a very able mathematician.His 1861 booklet, "Chemische Studien" ("chemical studies"), proposed two-dimensional representations for over 300
molecule s in a style [] remarkably similar to that used by modern chemists. [cite web | author = Rzepa, Henry S. | date = 2005 | url = http://www.ch.ic.ac.uk/rzepa/loschmidt/ | title = Joseph Loschmidt: Structural formulae, 1861 | accessdate = 2008-09-28] Among these were aromatic molecules such asbenzene (C6H6), and relatedtriazines . Loschmidt symbolized the benzene nucleus by a large circle, which he said was to indicate the yet-undetermined structure of the compound. Some have argued, however, that he intended this as the suggestion of a cyclical structure, four years before that of Kekulé, who is better known and is generally credited with the discovery of benzene's cyclic structure.In 1865, Loschmidt was the first to estimate the size of the molecules that make up the air: [cite journal | first = J. | last = Loschmidt | authorlink = Johann Josef Loschmidt | title = Zur Grösse der Luftmoleküle | journal = Sitzungsberichte der kaiserlichen Akademie der Wissenschaften Wien | volume = 52 | issue = 2 | pages = 395–413 | year =1865 [http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Loschmidt-1865.html English translation] .] his result was only twice the true size, a remarkable feat given the approximations he had to make. His method allowed the size of any gas molecules to be related to measurable phenomena, and hence to determine how many molecules are present in a given volume of gas. This latter quantity is now known as the
Loschmidt constant in his honour, and its modern value is 26.9 million million million molecules per cubic centimetre. [CODATA2006|url=http://physics.nist.gov/cgi-bin/cuu/Value?n0]Loschmidt and his younger university colleague
Ludwig Boltzmann became good friends. His critique of Boltzmann's attempt to derive thesecond law of thermodynamics fromkinetic theory became famous as the "reversibility paradox ". It led Boltzmann to his statistical concept ofentropy as a logarithmic tally of the number ofmicroscopic state s corresponding to a giventhermodynamic state .Loschmidt 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
* John Buckingham: "Chasing the Molecule"; Sutton Publishing, 2004, Gloucestershire. - ISBN 0-7509-3345-3External 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
* http://www.loschmidt.cz/
* http://www.ch.ic.ac.uk/rzepa/loschmidt/Persondata
NAME= Loschmidt, Johann Josef
ALTERNATIVE NAMES=Loschmidt, Josef
SHORT DESCRIPTION= Austrian chemist, physicist
DATE OF BIRTH=March 15 1821
PLACE OF BIRTH= Počerny (Putschirn, now part ofKarlovy Vary ,Czech Republic )
DATE OF DEATH=July 8 1895
PLACE OF DEATH=Vienna ,Austria
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