Claude Louis Berthollet
Claude Louis Berthollet (9 December 1748 – 6 November 1822) was a Savoy
Duchy of Savoy
From 1416 to 1847, the House of Savoy ruled the eponymous Duchy of Savoy . The Duchy was a state in the northern part of the Italian Peninsula, with some territories that are now in France. It was a continuation of the County of Savoy...

ard-French chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...

 who became vice president of the French Senate
French Senate
The Senate is the upper house of the Parliament of France, presided over by a president.The Senate enjoys less prominence than the lower house, the directly elected National Assembly; debates in the Senate tend to be less tense and generally enjoy less media coverage.-History:France's first...

 in 1804.


Claude Louis Berthollet was born in Talloires
Talloires is a commune in the Haute-Savoie department in the Rhône-Alpes region in south-eastern France.-Geography:Talloires is located south of Geneva, Switzerland, on Lake Annecy and from the local "prefecture" Annecy, near the border of Italy...

, near Annecy
Annecy is a commune in the Haute-Savoie department in the Rhône-Alpes region in south-eastern France.It lies on the northern tip of Lake Annecy , 35 kilometres south of Geneva.-Administration:...

, then part of the Duchy of Savoy
Duchy of Savoy
From 1416 to 1847, the House of Savoy ruled the eponymous Duchy of Savoy . The Duchy was a state in the northern part of the Italian Peninsula, with some territories that are now in France. It was a continuation of the County of Savoy...

, in 1749.

Berthollet, along with Antoine Lavoisier
Antoine Lavoisier
Antoine-Laurent de Lavoisier , the "father of modern chemistry", was a French nobleman prominent in the histories of chemistry and biology...

 and others, devised a chemical nomenclature, or a system of names, which serves as the basis of the modern system of naming chemical compounds. He also carried out research into dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

s and bleaches, being first to introduce the use of chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 gas as a commercial bleach in 1785. He also determined the composition of ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

. Berthollet was one of the first chemists to recognize the characteristics of a reverse reaction, and hence, chemical equilibrium
Chemical equilibrium
In a chemical reaction, chemical equilibrium is the state in which the concentrations of the reactants and products have not yet changed with time. It occurs only in reversible reactions, and not in irreversible reactions. Usually, this state results when the forward reaction proceeds at the same...

. Potassium chlorate
Potassium chlorate
Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use...

 (KClO3), a strong oxidizer, is known as Berthollet's Salt.

Berthollet was engaged in a long-term battle with another French chemist Joseph Proust
Joseph Proust
Joseph Louis Proust was a French chemist.-Life:Joseph L. Proust was born on September 26, 1754 in Angers, France. His father served as an apothecary in Angers. Joseph studied chemistry in his father’s shop and later came to Paris where he gained the appointment of apothecary in chief to the...

 on the validity of the law of definite proportions
Law of definite proportions
In chemistry, the law of definite proportions, sometimes called Proust's Law, states that a chemical compound always contains exactly the same proportion of elements by mass. An equivalent statement is the law of constant composition, which states that all samples of a given chemical compound have...

. While Proust believed that chemical compounds are composed of a fixed ratio of their constituent elements irrespective of the methods of production, Berthollet believed that this ratio can change according to the ratio of the reactants initially taken. Although Proust proved his theory by accurate measurements, his theory was not immediately accepted partially due to Berthollet's authority. His law was finally accepted when Berzelius
Berzelius is a secret society at Yale University named for the Swedish scientist Jöns Jakob Berzelius, considered one of the founding fathers of modern chemistry...

 confirmed it in 1811. But it was found later that Berthollet was not completely wrong because there exists a class of compounds that do not obey the law of definite proportions. These non-stoichiometric compound
Non-stoichiometric compound
Non-stoichiometric compounds are chemical compounds with an elemental composition that cannot be represented by a ratio of well-defined natural numbers, and therefore violate the law of definite proportions. Often, they are solids that contain crystallographic point defects, such as interstitial...

s are also named berthollides in his honor.

Berthollet was one of several scientists who went with Napoleon to Egypt, and was a member of the physics and natural history section of the Institut d'Égypte
Institut d'Égypte
The Institut d’Égypte was a learned academy formed by Napoleon Bonaparte to carry out research during his Egyptian campaign.-Early work:It first met on 24 August 1798, with Gaspard Monge as president, Bonaparte himself as vice-president and Joseph Fourier and Costaz as secretaries...


In April, 1789 he was elected a Fellow of the Royal Society of London. In 1801, he was elected a foreign member of the Royal Swedish Academy of Sciences
Royal Swedish Academy of Sciences
The Royal Swedish Academy of Sciences or Kungliga Vetenskapsakademien is one of the Royal Academies of Sweden. The Academy is an independent, non-governmental scientific organization which acts to promote the sciences, primarily the natural sciences and mathematics.The Academy was founded on 2...

. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences
American Academy of Arts and Sciences
The American Academy of Arts and Sciences is an independent policy research center that conducts multidisciplinary studies of complex and emerging problems. The Academy’s elected members are leaders in the academic disciplines, the arts, business, and public affairs.James Bowdoin, John Adams, and...

 in 1822.

He died in Arcueil
Arcueil is a commune in the Val-de-Marne department in the southern suburbs of Paris, France. It is located from the center of Paris.-Name:The name Arcueil was recorded for the first time in 1119 as Arcoloï, and later in the 12th century as Arcoïalum, meaning "place of the arches" , in...

, France in 1822.

Further reading

See also

Society of the Friends of Truth
Society of the Friends of Truth
The Society of the Friends of Truth , also known as the Social Club, was a French revolutionary organization founded in 1790. It was "a mixture of revolutionary political club, the Masonic Lodge, and a literary salon"...

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