Johann Josef Loschmidt
Encyclopedia
Jan or Johann Josef Loschmidt (March 15, 1821 - July 8, 1895), who referred to himself mostly as 'Josef' (omitting his first name), was a notable Austria
n scientist who performed groundbreaking work in chemistry
, physics
(thermodynamics
, optics
, electrodynamics), and crystal
forms.
Born in Carlsbad, a town located in the Austrian Empire
(now Karlovy Vary
, Czech Republic
), Loschmidt became professor of physical chemistry
at the University 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 the Piarist monastery in Schlackenwerth and, in 1837, to advanced high-school classes in Prague
.
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 professor Franz 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. Among these were aromatic molecules such as benzene
(C6H6), and related triazines. 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 in his honour, and its modern value is 2.69 x 1019 molecules per cubic centimetre.
Loschmidt and his younger university colleague Ludwig Boltzmann
became good friends. His critique of Boltzmann's attempt to derive the second law of thermodynamics
from kinetic theory
became famous as the "reversibility paradox". It led Boltzmann to his statistical concept of entropy
as a logarithmic tally of the number of microscopic states corresponding to a given thermodynamic 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.
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
n scientist who performed groundbreaking work in chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
(thermodynamics
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
, optics
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...
, electrodynamics), and crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
forms.
Born in Carlsbad, a town located in the Austrian Empire
Austrian Empire
The Austrian Empire was a modern era successor empire, which was centered on what is today's Austria and which officially lasted from 1804 to 1867. It was followed by the Empire of Austria-Hungary, whose proclamation was a diplomatic move that elevated Hungary's status within the Austrian Empire...
(now Karlovy Vary
Karlovy Vary
Karlovy Vary is a spa city situated in western Bohemia, Czech Republic, on the confluence of the rivers Ohře and Teplá, approximately west of Prague . It is named after King of Bohemia and Holy Roman Emperor Charles IV, who founded the city in 1370...
, Czech Republic
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
), Loschmidt became professor of physical chemistry
Physical chemistry
Physical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts...
at the University of Vienna
University of Vienna
The University of Vienna is a public university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world...
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 monastery in Schlackenwerth and, in 1837, to advanced high-school classes in Prague
Prague
Prague is the capital and largest city of the Czech Republic. Situated in the north-west of the country on the Vltava river, the city is home to about 1.3 million people, while its metropolitan area is estimated to have a population of over 2.3 million...
.
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 professor Franz S. Exner
Franz S. Exner
Franz Serafin Exner was an Austrian physicist.-Life:Exner comes from one of the most important university families of the Austrian-Hungarian empire. The same Exner family includes Adolf Exner, Karl Exner, Sigmund Exner, and Marie von Frisch. Exner the youngest of five children of parents Franz...
, 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
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
s in a style remarkably similar to that used by modern chemists. Among these were aromatic molecules such as benzene
Benzene
Benzene is an organic chemical compound. It is composed of 6 carbon atoms in a ring, with 1 hydrogen atom attached to each carbon atom, with the molecular formula C6H6....
(C6H6), and related triazines. 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
Friedrich August Kekulé von Stradonitz
Friedrich August Kekule von Stradonitz was a German organic chemist. From the 1850s until his death, Kekule was one of the most prominent chemists in Europe, especially in theoretical chemistry...
, 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 in his honour, and its modern value is 2.69 x 1019 molecules per cubic centimetre.
Loschmidt and his younger university colleague Ludwig Boltzmann
Ludwig Boltzmann
Ludwig Eduard Boltzmann was an Austrian physicist famous for his founding contributions in the fields of statistical mechanics and statistical thermodynamics...
became good friends. His critique of Boltzmann's attempt to derive the second law of thermodynamics
Second law of thermodynamics
The second law of thermodynamics is an expression of the tendency that over time, differences in temperature, pressure, and chemical potential equilibrate in an isolated physical system. From the state of thermodynamic equilibrium, the law deduced the principle of the increase of entropy and...
from kinetic theory
Kinetic theory
The kinetic theory of gases describes a gas as a large number of small particles , all of which are in constant, random motion. The rapidly moving particles constantly collide with each other and with the walls of the container...
became famous as the "reversibility paradox". It led Boltzmann to his statistical concept of entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
as a logarithmic tally of the number of microscopic states corresponding to a given thermodynamic state
Thermodynamic state
A thermodynamic state is a set of values of properties of a thermodynamic system that must be specified to reproduce the system. The individual parameters are known as state variables, state parameters or thermodynamic variables. Once a sufficient set of thermodynamic variables have been...
.
Loschmidt retired from university in 1891 and died in 1895 in Vienna
Vienna
Vienna is the capital and largest city of the Republic of Austria and one of the nine states of Austria. Vienna is Austria's primary city, with a population of about 1.723 million , and is by far the largest city in Austria, as well as its cultural, economic, and political centre...
. His only child had died before him at the age of ten.
External links
- 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/