Johann Josef Loschmidt (15 March 1821 – 8 July 1895), who referred to himself mostly as Josef Loschmidt (omitting his first name), was a notable
Austria
Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
n scientist who performed ground-breaking work in
chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...
,
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
(
thermodynamics
Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of the ...
,
optics
Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...
,
electrodynamics
In physics, electromagnetism is an interaction that occurs between particles with electric charge. It is the second-strongest of the four fundamental interactions, after the strong force, and it is the dominant force in the interactions of a ...
), and
crystal
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
forms.
Born in Karlsbad, a town located in the
Austrian Empire
The Austrian Empire (german: link=no, Kaiserthum Oesterreich, modern spelling , ) was a Central-Eastern European multinational great power from 1804 to 1867, created by proclamation out of the realms of the Habsburgs. During its existence, ...
(now
Karlovy Vary
Karlovy Vary (; german: Karlsbad, formerly also spelled ''Carlsbad'' in English) is a spa town, spa city in the Karlovy Vary Region of the Czech Republic. It has about 46,000 inhabitants. It lies on the confluence of the rivers Ohře and Teplá. ...
,
Czech Republic
The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...
), Loschmidt became professor of
physical chemistry
Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mecha ...
at the
University of Vienna
The University of Vienna (german: Universität Wien) is a public research university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world. With its long and rich histor ...
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 the
Piarist
The Piarists (), officially named the Order of Poor Clerics Regular of the Mother of God of the Pious Schools ( la, Ordo Clericorum Regularium pauperum Matris Dei Scholarum Piarum), abbreviated SchP, is a religious order of clerics regular of the ...
monastery in
Schlackenwerth and, in 1837, to advanced high-school classes in
Prague
Prague ( ; cs, Praha ; german: Prag, ; la, Praga) is the capital and largest city in the Czech Republic, and the historical capital of Bohemia. On the Vltava river, Prague is home to about 1.3 million people. The city has a temperate ...
.
This was followed by two years of philosophy and mathematics at Prague's
Charles University
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, type = Public, Ancient
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, rector = Milena Králíčková
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, undergr ...
, where Loschmidt met his second important mentor. This was the philosophy professor
Franz Serafin 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.
The era, when Loschmidt gradually developed his ideas on molecular structures, was to be a notable epoch in science. It was the time when
the Kinetic Theory of Gases was being developed.
His 1861 booklet, ''Chemische Studien'' ("chemical studies"), proposed two-dimensional representations for over 300
molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...
s in a style remarkably similar to that used by modern chemists. Among these were aromatic molecules such as
benzene
Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...
(C
6H
6), and related
triazines
Triazines are a class of nitrogen-containing heterocycles. The parent molecules' molecular formula is . They exist in three isomeric forms, 1,3,5-triazines being common.
Structure
The triazines have planar six-membered benzene-like ring but ...
. 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: 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
The ''Loschmidt constant'' or Loschmidt's number (symbol: ''n''0) is the number of particles (atoms or molecules) of an ideal gas in a given volume (the number density), and usually quoted at standard temperature and pressure. The 2014 CODATA reco ...
in his honour, and its modern value is molecules per cubic centimetre at
standard temperature and pressure
Standard temperature and pressure (STP) are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union o ...
(STP).
Loschmidt and his younger university colleague
Ludwig Boltzmann
Ludwig Eduard Boltzmann (; 20 February 1844 – 5 September 1906) was an Austrian physicist and philosopher. His greatest achievements were the development of statistical mechanics, and the statistical explanation of the second law of thermodyn ...
became good friends. His critique of Boltzmann's attempt to derive the
second law of thermodynamics
The second law of thermodynamics is a physical law based on universal experience concerning heat and Energy transformation, energy interconversions. One simple statement of the law is that heat always moves from hotter objects to colder objects ( ...
from
kinetic theory
Kinetic (Ancient Greek: κίνησις “kinesis”, movement or to move) may refer to:
* Kinetic theory, describing a gas as particles in random motion
* Kinetic energy, the energy of an object that it possesses due to its motion
Art and ente ...
became famous as the "
reversibility paradox
Loschmidt's paradox, also known as the reversibility paradox, irreversibility paradox or ', is the objection that it should not be possible to deduce an irreversible process from time-symmetric dynamics. This puts the time reversal symmetry of (alm ...
". It led Boltzmann to his statistical concept of
entropy
Entropy is a scientific concept, as well as a measurable physical property, that is most commonly associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynam ...
as a logarithmic tally of the number of
microstates
A microstate or ministate is a sovereign state having a very small population or very small land area, usually both. However, the meanings of "state" and "very small" are not well-defined in international law.Warrington, E. (1994). "Lilliputs ...
corresponding to a given
thermodynamic state
In thermodynamics, a thermodynamic state of a system is its condition at a specific time; that is, fully identified by values of a suitable set of parameters known as state variables, state parameters or thermodynamic variables. Once such a set o ...
.
Loschmidt retired from university in 1891 and died in 1895 in
Vienna
en, Viennese
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, postal_code_type = Postal code
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.
References
Further reading
* 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. -
* John Buckingham: ''Chasing the Molecule''; Sutton Publishing, 2004, Gloucestershire. -
External links
*
* https://web.archive.org/web/20080201124625/http://scienceweek.com/2004/rmps-15.htm
* http://www.uh.edu/engines/epi1858.htm
* https://web.archive.org/web/20080224030257/http://www.loschmidt.cz/
* http://www.ch.ic.ac.uk/rzepa/loschmidt/
Pioneering Ideas for the Physical and Chemical Sciences
{{DEFAULTSORT:Loschmidt, Johann Josef
19th-century Austrian physicists
Austrian physical chemists
1821 births
1895 deaths
People from Karlovy Vary
German Bohemian people
Charles University alumni