Antoine Lavoisier - Father of Modern Chemistry

39
Journal of the association of physicians of india • vol 63 • march, 2015
Antoine Lavoisier - Father of Modern Chemistry
JV Pai-Dhungat*, Falguni Parikh**
Antoine Lavoisier, San Marino, 1982
Antoine Lavoisier, Stamp-France 1943
150th Anniversary of French Revolution Stamp-France 1939
A
ntoine Laurent Lavoisier (1743-1794) was
born in Paris. One of the great figures in
science, he is often called father of modern
chemistry. Priestly, in 1774 had heated brick
red calx (mercuric oxide), obtaining back
mercury, and in addition a combustible gas,
with most unusual properties, He called
it “dephlogisticated air” (oxygen). It was
held that combustible objects, were rich
in phlogiston (Greek -to set on fire) and
the process of combustion involved loss of
phlogiston. However, the phlogiston theory
could not explain many things.
From the very beginning of his chemical
researches, Lavoisier recognised the importance
of accurate measurements. With this he was
able to show, that the layer of calx, obtained
on the surface of heated metals like tin and
lead was heavier than the metal it replaced.
He postulated it to be a combination of metal
with air, because rusting and combustion did
not involve a loss of phlogiston, but a gain of
at least some portion of air.
Repeating Priestley’s experiment, he
immediately recognised that the notion of
dephlogisticated air was erroneous. The very
reason, that objects burned readily in the new
gas was, that it was undiluted by that portion
of air in which objects did not burn.
*
Professor of Medicine, T.N.
Medical College (Retd.), Hon.
Physician, Bhatia Hospital,
Mumbai; **Consultant Internal
Medicine and Infectious
Diseases, Kokilaben Dhirubhai
Ambani Hospital,
Andheri (West), Mumbai
In 1777, he announced that air consisted of
two gases, one which supported, combustion
and the other, which did not. Lavoisier called
the former oxygen (Greek- “giving rise to
acids”), and the latter “azote” (Greek-”no
life”). In 1790, it was named nitrogen by
Chaptal.
Though, Priestly had discovered oxygen,
it was Lavoisier who clearly demonstrated
its nature and oxidation, overthrowing the
entire phlogiston theory, causing a complete
change in chemical terminology. He studied
the behaviour of animals in air, oxygen and
nitrogen. He measured the amount of heat that
they produced, proving that life was very much
like combustion.
Unfortunately, Lavoisier’s talents were
applied to many fields, some of them political
He joined Ferme-generale, a tax collecting
company which acted for the government,
in order to earn money for his researches in
1768. Thus he was a tax-farmer, and married
the daughter of the important executive of the
firm. All his activities had made him a figure
of prominence. French Revolution broke out in
1789 and by 1792, the radical anti-monarchist
were in control. France was described a
Republic and the tax farmers were hunted
out. Thus it was Ferme-generale association
which barred, Lavoisier from his laboratory
and arrested him with 27 others, and their
property was confiscated. A plea for Lavoisier,
on the ground of his great scientific ability, was
rejected with a famous remark. ‘The Republic
has no need of scientists’. The trial was a farce,
and all were sentenced to death within 24
hours. Lavoisier fell a victim to the fury of “the
Friends of the People” and was guillotined in
1794. His death was the most deplorable, single
causality of Revolution. Within two years, the
regretful French unveiled his bust.