Editing Pierre Louis Dulong (section)

== Career ==
In chemistry, he contributed to knowledge on:
* the double decomposition of salts (1811)
* [[nitrous acid]] (1815)
* the [[oxide]]s of [[phosphorus]] (1816)
* the oxides of [[nitrogen]]
* [[catalysis]] by metals (1823, with Thénard).

Dulong also discovered the dangerously sensitive [[nitrogen trichloride]] in 1811, losing three fingers and an eye in the process.<ref>{{cite journal|year=1813|title=Report on the work of Pierre Louis Dulong|journal=[[Annales de Chimie et de Physique]]|volume=86|issue=6|pages=37&ndash;43|author=Thénard J. L.|author2=Berthollet C. L.|author-link2=Claude Louis Berthollet|author-link=Louis Jacques Thénard}}</ref> The fact that Dulong kept the accident a secret meant that [[Humphry Davy]]'s investigation of the compound had the same unfortunate consequence, although Davy's injuries were less severe.<ref>{{Cite journal|last=Hale|first=William|date=April 1888|title=Formation of the Explosive Chloride of Nitrogen by Electrolysis|jstor=1764740|journal=Science|volume=11|issue=273|pages=206|bibcode=1888Sci....11..206H|doi=10.1126/science.ns-11.273.206.a|pmid=17806755|s2cid=239564780 |url=https://zenodo.org/record/1448313}}</ref>

In addition to his accomplishments in chemistry, Dulong has been hailed as an interdisciplinary expert. His contemporaries in the [[Royal Society|Royal Society of London]] acknowledged his "command of almost every department of physical science".<ref name=":3">{{Cite book|url=https://play.google.com/books/reader?printsec=frontcover&output=reader&id=gw9LAQAAMAAJ&pg=GBS.RA2-PA97|title=Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London|last=Britain)|first=Royal Society (Great|date=1837-01-01|publisher=Richard Taylor|language=en}}</ref>

In 1815, Dulong collaborated for the first time with [[Alexis Thérèse Petit]], in publishing a paper on heat expansion.<ref name=":0">{{Cite journal|last=Lemay|first=Pierre|date=1948|title=Pierre Louis Dulong, His Life and Work|jstor=27757122|journal=Chymia|volume=1|pages=171–190|doi=10.2307/27757122}}</ref> The two would continue to collaborate, researching the specific heats of metals. In 1819, Dulong and Petit showed that the mass heat capacity of [[metal]]lic [[Chemical element|elements]] are inversely proportional to their [[atomic mass]]es, this being now known as the [[Dulong–Petit law]].<ref name=":4">{{cite journal|year=2006|title=Dulong and Petit's Law: We Should Not Ignore Its Importance|journal=Journal of Chemical Education|volume=83|issue=10|pages=1499&ndash;1504|bibcode=2006JChEd..83.1499L|doi=10.1021/ed083p1499|author=Laing, Mary|author2=Laing, Michael}}</ref> For this discovery  Dulong was honored by the [[Académie française|French Academy]] in 1818. This law helped develop the periodic table and, more broadly, the examination of atomic masses.<ref name=":4" />

In 1820, Dulong succeeded Petit, who retired due to poor health,<ref name=":0" /> as professor of physics at [[École Polytechnique|École polytechnique]]. Dulong studied the elasticity of steam, the measurement of temperatures, and the behavior of elastic fluids. He studied how metals enabled the combinations of certain gases.<ref name=":1">{{Cite encyclopedia |title=Pierre-Louis Dulong {{!}} French scientist |encyclopedia=Encyclopedia Britannica |url=https://www.britannica.com/biography/Pierre-Louis-Dulong |access-date=2017-05-05 |language=en}}</ref> He made the first precise comparison of the mercury- and air-temperature scales. In 1830, he was elected a foreign member of the [[Royal Swedish Academy of Sciences]].

He died of stomach cancer in [[Paris]]. At the time of his death, he was working on the development of precise methods in [[calorimetry]]. His last paper, published the year of his death, examined the heat released from chemical reactions.<ref name=":1" />