Editing Jean Stas (section)

== 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 Academy (Belgium)|Royal Military School]] in [[Brussels]]. He acquired international fame by determining the atomic weights of the [[Element (chemistry)|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 table|periodic system of elements]] of [[Dmitri Mendeleev]] and others.<ref>{{cite journal | last = Rawson | first = Don C. | year = 1974 | title = The process of discovery: Mendeleev and the periodic law | journal = Annals of Science | volume = 31 | issue = 3 | pages = 181&ndash;204 | doi = 10.1080/00033797400200221}}</ref>

Following the pioneering work of [[Antoine Lavoisier|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 reaction]]s,<ref>Matthew Moncrieff Pattison Muir, [https://books.google.com/books?id=EwZZAAAAYAAJ ''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"[https://books.google.com/books?id=bhQ3AAAAYAAJ ''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, [https://archive.org/details/acourseingenera00hendgoog ''A Course in General Chemistry''] (1921)</ref> The difference in the accuracy aimed at and attained by Lavoisier on the one hand, and by [[Edward Morley|Morley]] and Stas on the other, is enormous.<ref>[[Ida Freund]], [https://archive.org/details/studychemicalco01freugoog ''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>{{cite journal
|last=Wennig
|first=Robert
|date=April 2009|title=Back to the roots of modern analytical toxicology: Jean Servais Stas and the Bocarmé murder case
|journal=Drug Test Anal
|volume=1
|issue=4
|pages=153–5
|location = England| pmid = 20355192
|doi = 10.1002/dta.32
 }}</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]].