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

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a graduated scientist trained in the study of chemistry, or an officially enrolled student in the field. Chemists study the composition of ...

who accurately measured 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; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

Life and work

Stas was born in

Leuven Leuven (, , ), also called Louvain (, , ), is the capital and largest City status in Belgium, city of the Provinces of Belgium, province of Flemish Brabant in the Flemish Region of Belgium. It is located about east of Brussels. The municipalit ...

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 physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

and worked at the

École Polytechnique (, ; also known as Polytechnique or l'X ) is a ''grande école'' located in Palaiseau, France. It specializes in science and engineering and is a founding member of the Polytechnic Institute of Paris. The school was founded in 1794 by mat ...

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 measuri ...

. Stas and Dumas established the

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

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

, and then weighing the

carbon dioxide Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...

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, officially the Brussels-Capital Region, (All text and all but one graphic show the English name as Brussels-Capital Region.) is a Communities, regions and language areas of Belgium#Regions, region of Belgium comprising #Municipalit ...

. He acquired international fame by determining the atomic weights of the

elements Element or elements may refer to: Science * Chemical element, a pure substance of one type of atom * Heating element, a device that generates heat by electrical resistance * Orbital elements, parameters required to identify a specific orbit of o ...

more accurately than had ever been done before, using an

atomic mass Atomic mass ( or ) is the mass of a single atom. The atomic mass mostly comes from the combined mass of the protons and neutrons in the nucleus, with minor contributions from the electrons and nuclear binding energy. The atomic mass of atoms, ...

of 16 for

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

William Prout William Prout Fellow of the Royal Society, 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 H ...

that all atomic weights must be integer multiples of that of

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

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

periodic system of elements Periodicity or periodic may refer to: Mathematics * Bott periodicity theorem, addresses Bott periodicity: a modulo-8 recurrence relation in the homotopy groups of classical groups * Periodic function, a function whose output contains values tha ...

Dmitri Mendeleev Dmitri Ivanovich Mendeleev ( ; ) was a Russian chemist known for formulating the periodic law and creating a version of the periodic table of elements. He used the periodic law not only to correct the then-accepted properties of some known ele ...

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 the mass of the system must remain constant over time. The law implies that mass can neith ...

, 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 chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

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 and Stas on the other, is enormous. In 1850, Stas gave the evidence that the Belgian Count

Hippolyte Visart de Bocarmé Hippolyte Visart de Bocarmé (Weltevreden, Java 14 June 1818 – Mons, Belgium 19 July 1851) was a Belgian nobleman and convicted murderer. He poisoned his brother-in-law in order to acquire some urgently needed money. In 1851, the chemist Jea ...

killed his brother-in-law by poisoning him with

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

. 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 affect monetary and other financial conditions to accomplish broader objectives like high employment and price stability (normally interpreted as a low and stable rat ...

. 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). Re ...

(1885) * On May 5, 1891 an event was held recognizing the 50th anniversary of Jean Servais Stas' membership in the

Royal Academy of Belgium The Royal Academies for Science and the Arts of Belgium (RASAB) is a non-governmental association that promotes and organises science and the arts in Belgium by coordinating the national and international activities of its constituent academies su ...

. 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. Stas-3

Selected writings

* * * * Stas, Jean Servais (1865).
Nouvelles recherches sur les lois des proportions chimiques : sur les poids atomiques et leurs rapports mutuels
'. Brussels: Bruxelles. M. Hayez

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 biologists Toxicologists Academic staff of the Royal Military Academy (Belgium)

Life and work

Honors and awards

Selected writings

See also

Further reading

References