Jean Servais Stas (21 August 1813 – 13 December 1891) was a

Belgian Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct languag ...

analytical

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...

who co-discovered the

atomic weight Relative atomic mass (symbol: ''A''; sometimes abbreviated RAM or r.a.m.), also known by the deprecated synonym atomic weight, is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a giv ...

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...

Life and work

Stas was born in

Leuven Leuven (, ) or Louvain (, , ; german: link=no, Löwen ) is the capital and largest city of the province of Flemish Brabant in the Flemish Region of Belgium. It is located about east of Brussels. The municipality itself comprises the historic c ...

and trained initially as a physician. He later switched to

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...

and worked at the

École Polytechnique École may refer to: * an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée) * École (river), a tributary of the Seine flowing in région Île-de-France * École, Savoi ...

in Paris under the direction of

Jean-Baptiste Dumas Jean Baptiste André Dumas (14 July 180010 April 1884) was a French chemist, best known for his works on organic analysis and synthesis, as well as the determination of atomic weights (relative atomic masses) and molecular weights by measuring ...

. Stas and Dumas established the

by weighing a sample of the pure material, burning it in pure

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

, and then weighing the

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

produced. In 1840, Stas was appointed professor at the

Royal Military School Koninklijke Militaire School (KMS) is a Dutch military school in the Netherlands training soldiers and non-commissioned officers for the Royal Netherlands Army. History The KMS began as the Onderofficiers School (OOS), in 1952, in Weert; it was ...

Brussels Brussels (french: Bruxelles or ; nl, Brussel ), officially the Brussels-Capital Region (All text and all but one graphic show the English name as Brussels-Capital Region.) (french: link=no, Région de Bruxelles-Capitale; nl, link=no, Bruss ...

. He acquired international fame by determining the atomic weights of the elements more accurately than had ever been done before, using an

atomic mass The atomic mass (''m''a or ''m'') is the mass of an atom. Although the SI unit of mass is the kilogram (symbol: kg), atomic mass is often expressed in the non-SI unit dalton (symbol: Da) – equivalently, unified atomic mass unit (u). 1&n ...

of 16 for

as his standard. His results disproved the hypothesis of the English physicist

William Prout William Prout FRS (; 15 January 1785 – 9 April 1850) was an English chemist, physician, and natural theologian. He is remembered today mainly for what is called Prout's hypothesis. Biography Prout was born in Horton, Gloucestershire in ...

that all atomic weights must be integer multiples of that of

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...

. These careful, accurate atomic weight measurements of Stas helped lay the foundation for the periodic system of elements of

Dmitri Mendeleev Dmitri Ivanovich Mendeleev (sometimes transliterated as Mendeleyev or Mendeleef) ( ; russian: links=no, Дмитрий Иванович Менделеев, tr. , ; 8 February Old_Style_and_New_Style_dates">O.S._27_January.html" ;"title="O ...

and others. Following the pioneering work of

Lavoisier Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794),
CNRS ( conservation of mass In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass can ...

, the prolonged and exhaustive experiments of Stas supported the strict accuracy of this law in

chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...

s, even though they were carried out with other intentions. His research indicated that in certain reactions the loss or gain could not have been more than from 2 to 4 parts in 100,000. The difference in the accuracy aimed at and attained by Lavoisier on the one hand, and by

Morley Morley may refer to: Places England * Morley, Norfolk, a civil parish * Morley, Derbyshire, a civil parish * Morley, Cheshire, a village * Morley, County Durham, a village * Morley, West Yorkshire, a suburban town of Leeds and civil parish * M ...

and Stas on the other, is enormous. In 1850, Stas gave the evidence that the Belgian Count Hippolyte Visart de Bocarmé killed his brother-in-law by poisoning him with

nicotine Nicotine is a naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and '' Duboisia hopwoodii'') and is widely used recreationally as a stimulant and anxiolytic. As a pharmaceutical drug, it is use ...

. Stas retired in 1869 because of problems with his voice caused by a throat ailment. He became commissioner of the mint, but resigned in 1872 because he disagreed with the government's

monetary policy Monetary policy is the policy adopted by the monetary authority of a nation to control either the interest rate payable for federal funds, very short-term borrowing (borrowing by banks from each other to meet their short-term needs) or the money s ...

. Jean Stas died in

and was buried at

Honors and awards

* Foreign Member,

Royal Society of London The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, r ...

(1879) *

Davy Medal The Davy Medal is awarded by the Royal Society of London "for an outstandingly important recent discovery in any branch of chemistry". Named after Humphry Davy, the medal is awarded with a monetary gift, initially of £1000 (currently £2000). H ...

(1885) * On May 5, 1891 an event was held recognizing the 50th anniversary of Jean Servais Stas' membership in the Royal Academy of Belgium. Various presenters spoke about his significant scientific contributions. He was presented with a medal in his honor sculpted by Belgian engraver Alphonse Michaux and with an album containing accolades authored by scientific societies from around the world.L'Academie Royale des Sciences, des Lettres et des Beaux-Arts de Belgique, ''Manifestation en L'Honneur de Jean-Servais Stas a L'Occasion du Cinquantieme Anniversaire de Sa Nomination Comme Membre Titulaire de la Classe des Sciences 1841 - 1891'', Bruxelles, 1891.

Selected writings

* * *

References

{{DEFAULTSORT:Stas, Jean 1813 births 1891 deaths Belgian chemists Scientists from Leuven Foreign Members of the Royal Society Foreign associates of the National Academy of Sciences Belgian toxicologists Academic staff of Royal Military Academy (Belgium)

Life and work

Honors and awards

Selected writings

See also

Further reading

References