Jean Stas

Template:Short description Template:Infobox scientist Jean Servais Stas (21 August 1813 – 13 December 1891) was a Belgian analytical chemist who accurately measured the atomic weight of carbon.

Life and work

Stas was born in Leuven and trained initially as a physician. He later switched to chemistry and worked at the École Polytechnique in Paris under the direction of Jean-Baptiste Dumas. Stas and Dumas established the atomic weight of carbon by weighing a sample of the pure material, burning it in pure oxygen, and then weighing the carbon dioxide produced.

In 1840, Stas was appointed professor at the Royal Military School in Brussels. He acquired international fame by determining the atomic weights of the elements more accurately than had ever been done before, using an atomic mass of 16 for oxygen as his standard. His results disproved the hypothesis of the English physicist William Prout that all atomic weights must be integer multiples of that of hydrogen. These careful, accurate atomic weight measurements of Stas helped lay the foundation for the periodic system of elements of Dmitri Mendeleev and others.<ref>Template:Cite journal</ref>

Following the pioneering work of Lavoisier and his statement of the conservation of mass, the prolonged and exhaustive experiments of Stas supported the strict accuracy of this law in chemical reactions,<ref>Matthew Moncrieff Pattison Muir, The Elements of Chemistry (1904)</ref> even though they were carried out with other intentions. His research<ref>Nouv. Recherches sur los lois des proportions chimiques (1865) 152, 171, 189</ref><ref>"Conservation of Mass in Chemical Changes"Journal - Chemical Society, London, Vol.64, Part 2 Chemical Society (Great Britain)</ref> indicated that in certain reactions the loss or gain could not have been more than from 2 to 4 parts in 100,000.<ref>William Edwards Henderson, A Course in General Chemistry (1921)</ref> 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.<ref>Ida Freund, The study of Chemical Composition: an account of its method and historical development, with illustrative quotations (1904)</ref>

In 1850, Stas gave the evidence that the Belgian Count Hippolyte Visart de Bocarmé killed his brother-in-law by poisoning him with nicotine.<ref>Template:Cite journal</ref>

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. Jean Stas died in Brussels and was buried at Leuven.

Honors and awards

Foreign Member, Royal Society of London (1879)
Davy Medal (1885)
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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.<ref>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.</ref>

Nouvelles recherches sur les lois des proportions chimiques : sur les poids atomiques et leurs rapports mutuels (1865)

Nouvelles recherches sur les lois des proportions chimiques : sur les poids atomiques et leurs rapports mutuels (1865)