Eligio Perucca
Encyclopedia
Eligio Perucca was an Italian Physics
instructor and researcher at the University of Turin
in Italy
in the early decades of the twentieth century. He later served a professorship at the nearby Polytechnic University of Turin. He discovered an important principle in stereochemistry
in 1919, but his contribution was overlooked and forgotten until recently.
from the University of Pisa
at the astoundingly young age of 20. He became Assistant to Professor Naccari
in 1911 at the University of Turin
, a post he retained for 11 years.
In 1922 Perucca succeeded Professor Majorana
to the chair of Experimental Physics at the Polytechnic University of Turin
. He retained that appointment until 1960. In addition he was Rector of the Polytechnic from 1947–1955, and largely devoted his energy to rebuilding the physical facilities which had been destroyed during World War II
.
known as the Bilamina de Bravais-Perucca, which is still highly regarded for its precision.
In a paper published in 1919, Perucca reported an experiment which produced optical rotatory dispersion
(ORD) as a result of passing linearly polarized light through colored crystal
s of sodium chlorate
. Perucca was attempting to replicate a nineteenth-century experiment (1860) in which amethyst
exhibited optical activity in the visible light spectrum. He used a readily-available substitute for the amethyst. Sodium chlorate is chiral
as a crystal, but in its natural (undyed) state is transparent and does not exhibit enhanced optical activity, so Perucca added an organic dye (an equilibrium racemic mixture of a triarylmethane textile dye then known as extra China blue). His goal was to see if addition of the organic dye on the crystalline structure would induce enhanced optical activity (rotation) of light in the 500-600 nm absorption band on the otherwise optically inactive dye.
Perucca reported that the dyed crystal did exhibit the desired optical rotation. However, because his report was not widely distributed, his discovery of this stereochemistry
effect was not attributed to him, and when it was later studied by Paul Pfeiffer in Germany beginning in 1931 and reported in the literature, the effect eventually became known as the Pfeiffer Effect
.
Perucca's experiment was the forerunner of another field of study which arose in the 1970s, in connection with enantioselective adsorption of racemic mixtures on inorganic crystals. This study was a basic tool in determining the origin of the homochirality
of life - scientists are still trying to determine why present earth-based life is based almost exclusively on L-enantiomers, popularly known as left-handed proteins
.
During his tenure at the Turin Polytechnic, Perucca studied the Volta Effect
, measuring with high precision the electronegativity
between pairs of dissimilar metals. He was able to establish a theoretical correlation between the Volta Effect and the Peltier Effect. In 1928 he discovered that Enrico Fermi
's theory on free electrons
could be used to predict the constants of the photoelectric effect
and thermionic effect
in Volta's and Peltier's equations.
In 1930 Perucca turned his attention to the photoelectric effect
. He developed a new type of electric-current/voltage measuring device called the Elettrometro di Perucca which was highly sensitive.
chemistry professor Bart E. Kahr determined to compile a complete list of studies on crystal dyeing. He happened upon Perucca's nearly-forgotten paper. After studying and researching the subject, Kahr and associates Yonghong Bing and Werner Kaminsky repeated the experiment in 2008, using aniline blue as the dyeing compound. They did confirm the 1919 result. Kahr stated:
regime of Benito Mussolini
. However, his associates remember him as strongly anti-fascist, not a safe viewpoint in those days. In 1939 Perucca received Mussolini during an official visit to Turin
. Rather than donning the black attire which the Duce's supporters affected in his presence, Perucca made "a bold political statement" by wearing fancy ceremonial attire to the meeting.
Perucca once demanded that a student describe the Carnot Cycle
during an oral examination. The flustered student was unable to comply, so the professor directed him to draw a circle on the blackboard. He then directed him to draw another circle of equal size nearby. He then said the student had drawn a "Carnot bicycle", that he should get on and ride away, because he had failed the exam.
Perucca once asked a chemistry student why the laboratory's washbasins were located one meter above the laboratory's floor. The confused student stumbled through possibilities such as necessary hydraulic force or sanitary requirements. But Perucca failed the already demoralized student and explained that the basins were so located in order to allow the workers to wash their hands while standing up.
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...
instructor and researcher at the University of Turin
University of Turin
The University of Turin is a university in the city of Turin in the Piedmont region of north-western Italy...
in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
in the early decades of the twentieth century. He later served a professorship at the nearby Polytechnic University of Turin. He discovered an important principle in stereochemistry
Stereochemistry
Stereochemistry, a subdiscipline of chemistry, involves the study of the relative spatial arrangement of atoms within molecules. An important branch of stereochemistry is the study of chiral molecules....
in 1919, but his contribution was overlooked and forgotten until recently.
Life and career
Perucca received a Ph.D. degree in PhysicsPhysics
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...
from the University of Pisa
University of Pisa
The University of Pisa , located in Pisa, Tuscany, is one of the oldest universities in Italy. It was formally founded on September 3, 1343 by an edict of Pope Clement VI, although there had been lectures on law in Pisa since the 11th century...
at the astoundingly young age of 20. He became Assistant to Professor Naccari
Andrea Naccari
Andrea Naccari is notable for his study of the thermoelectric properties of metals, the photoelectric effect of metals immersed in liquids, and the electrical conductivity of gases and liquid dielectrics...
in 1911 at the University of Turin
University of Turin
The University of Turin is a university in the city of Turin in the Piedmont region of north-western Italy...
, a post he retained for 11 years.
In 1922 Perucca succeeded Professor Majorana
Quirino Majorana
Quirino Majorana was an Italian experimental physicist who investigated a wide range of phenomena during his long career as professor of physics at the Universities of Rome, Turin , and Bologna , Italy.-Work:...
to the chair of Experimental Physics at the Polytechnic University of Turin
Polytechnic University of Turin
The Polytechnic University of Turin is an engineering university based in Turin, northern Italy. Established in 1859, Politecnico di Torino is Italy’s oldest Technical University. In 2011 it was ranked as the best engineering university in Italy in the Academic Ranking of World Universities.It is...
. He retained that appointment until 1960. In addition he was Rector of the Polytechnic from 1947–1955, and largely devoted his energy to rebuilding the physical facilities which had been destroyed during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
.
Scientific achievements
Upon arriving at the University of Turin, Perucca launched into the study of polarized light. In 1913 he invented a sensitive light meterLight meter
A light meter is a device used to measure the amount of light. In photography, a light meter is often used to determine the proper exposure for a photograph...
known as the Bilamina de Bravais-Perucca, which is still highly regarded for its precision.
In a paper published in 1919, Perucca reported an experiment which produced optical rotatory dispersion
Optical rotatory dispersion
Optical rotatory dispersion is the variation in the optical rotation of a substance with a change in the wavelength of light. Optical rotatory dispersion can be used to find the absolute configuration of metal complexes....
(ORD) as a result of passing linearly polarized light through colored 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...
s of sodium chlorate
Sodium chlorate
Sodium chlorate is a chemical compound with the chemical formula . When pure, it is a white crystalline powder that is readily soluble in water. It is hygroscopic. It decomposes above 250 °C to release oxygen and leave sodium chloride...
. Perucca was attempting to replicate a nineteenth-century experiment (1860) in which amethyst
Amethyst
Amethyst is a violet variety of quartz often used in jewelry. The name comes from the Ancient Greek ἀ a- and μέθυστος methustos , a reference to the belief that the stone protected its owner from drunkenness; the ancient Greeks and Romans wore amethyst and made drinking vessels of it in the belief...
exhibited optical activity in the visible light spectrum. He used a readily-available substitute for the amethyst. Sodium chlorate is chiral
Chirality (chemistry)
A chiral molecule is a type of molecule that lacks an internal plane of symmetry and thus has a non-superimposable mirror image. The feature that is most often the cause of chirality in molecules is the presence of an asymmetric carbon atom....
as a crystal, but in its natural (undyed) state is transparent and does not exhibit enhanced optical activity, so Perucca added an organic dye (an equilibrium racemic mixture of a triarylmethane textile dye then known as extra China blue). His goal was to see if addition of the organic dye on the crystalline structure would induce enhanced optical activity (rotation) of light in the 500-600 nm absorption band on the otherwise optically inactive dye.
Perucca reported that the dyed crystal did exhibit the desired optical rotation. However, because his report was not widely distributed, his discovery of this stereochemistry
Stereochemistry
Stereochemistry, a subdiscipline of chemistry, involves the study of the relative spatial arrangement of atoms within molecules. An important branch of stereochemistry is the study of chiral molecules....
effect was not attributed to him, and when it was later studied by Paul Pfeiffer in Germany beginning in 1931 and reported in the literature, the effect eventually became known as the Pfeiffer Effect
Pfeiffer Effect
The Pfeiffer Effect is an optical phenomenon whereby the presence of an optically active compound influences the optical rotation of a racemic mixture of a second compound....
.
Perucca's experiment was the forerunner of another field of study which arose in the 1970s, in connection with enantioselective adsorption of racemic mixtures on inorganic crystals. This study was a basic tool in determining the origin of the homochirality
Homochirality
Homochirality is a term used to refer to a group of molecules that possess the same sense of chirality. Molecules involved are not necessarily the same compound, but similar groups are arranged in the same way around a central atom. In biology homochirality is found in the chemical building blocks...
of life - scientists are still trying to determine why present earth-based life is based almost exclusively on L-enantiomers, popularly known as left-handed proteins
Chirality (chemistry)
A chiral molecule is a type of molecule that lacks an internal plane of symmetry and thus has a non-superimposable mirror image. The feature that is most often the cause of chirality in molecules is the presence of an asymmetric carbon atom....
.
During his tenure at the Turin Polytechnic, Perucca studied the Volta Effect
Contact electrification
Contact electrification is an obsolete scientific theory from the Enlightenment that attempted to account for all the sources of electric charge known at the time. In the late 18th century, scientists developed sensitive instruments for detecting 'electrification', otherwise known as electrostatic...
, measuring with high precision the electronegativity
Electronegativity
Electronegativity, symbol χ , is a chemical property that describes the tendency of an atom or a functional group to attract electrons towards itself. An atom's electronegativity is affected by both its atomic number and the distance that its valence electrons reside from the charged nucleus...
between pairs of dissimilar metals. He was able to establish a theoretical correlation between the Volta Effect and the Peltier Effect. In 1928 he discovered that Enrico Fermi
Enrico Fermi
Enrico Fermi was an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics...
's theory on free electrons
Fermi-Dirac statistics
Fermi–Dirac statistics is a part of the science of physics that describes the energies of single particles in a system comprising many identical particles that obey the Pauli Exclusion Principle...
could be used to predict the constants of the photoelectric effect
Photoelectric effect
In the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as photoelectrons...
and thermionic effect
Thermionic emission
Thermionic emission is the heat-induced flow of charge carriers from a surface or over a potential-energy barrier. This occurs because the thermal energy given to the carrier overcomes the binding potential, also known as work function of the metal. The charge carriers can be electrons or ions, and...
in Volta's and Peltier's equations.
In 1930 Perucca turned his attention to the photoelectric effect
Photoelectric effect
In the photoelectric effect, electrons are emitted from matter as a consequence of their absorption of energy from electromagnetic radiation of very short wavelength, such as visible or ultraviolet light. Electrons emitted in this manner may be referred to as photoelectrons...
. He developed a new type of electric-current/voltage measuring device called the Elettrometro di Perucca which was highly sensitive.
Replication of experimental result (Nuovo Cimento)
In 2001, University of WashingtonUniversity of Washington
University of Washington is a public research university, founded in 1861 in Seattle, Washington, United States. The UW is the largest university in the Northwest and the oldest public university on the West Coast. The university has three campuses, with its largest campus in the University...
chemistry professor Bart E. Kahr determined to compile a complete list of studies on crystal dyeing. He happened upon Perucca's nearly-forgotten paper. After studying and researching the subject, Kahr and associates Yonghong Bing and Werner Kaminsky repeated the experiment in 2008, using aniline blue as the dyeing compound. They did confirm the 1919 result. Kahr stated:
"Perucca's paper should be viewed as a milestone in the chiroptics literature, as well as in the history of enantioselective chemistry."
Perucca's reputation
Perucca labored as a government employee during the fascistFascism
Fascism is a radical authoritarian nationalist political ideology. Fascists seek to rejuvenate their nation based on commitment to the national community as an organic entity, in which individuals are bound together in national identity by suprapersonal connections of ancestry, culture, and blood...
regime of Benito Mussolini
Benito Mussolini
Benito Amilcare Andrea Mussolini was an Italian politician who led the National Fascist Party and is credited with being one of the key figures in the creation of Fascism....
. However, his associates remember him as strongly anti-fascist, not a safe viewpoint in those days. In 1939 Perucca received Mussolini during an official visit to Turin
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...
. Rather than donning the black attire which the Duce's supporters affected in his presence, Perucca made "a bold political statement" by wearing fancy ceremonial attire to the meeting.
Perucca once demanded that a student describe the Carnot Cycle
Carnot cycle
The Carnot cycle is a theoretical thermodynamic cycle proposed by Nicolas Léonard Sadi Carnot in 1824 and expanded by Benoit Paul Émile Clapeyron in the 1830s and 40s. It can be shown that it is the most efficient cycle for converting a given amount of thermal energy into work, or conversely,...
during an oral examination. The flustered student was unable to comply, so the professor directed him to draw a circle on the blackboard. He then directed him to draw another circle of equal size nearby. He then said the student had drawn a "Carnot bicycle", that he should get on and ride away, because he had failed the exam.
Perucca once asked a chemistry student why the laboratory's washbasins were located one meter above the laboratory's floor. The confused student stumbled through possibilities such as necessary hydraulic force or sanitary requirements. But Perucca failed the already demoralized student and explained that the basins were so located in order to allow the workers to wash their hands while standing up.