Editing Chlorine (section)

===Isolation===
The element was first studied in detail in 1774 by Swedish chemist [[Carl Wilhelm Scheele]], and he is credited with the discovery.<ref>{{cite journal|last1=Scheele|first1=Carl Wilhelm|title=Om Brunsten, eller Magnesia, och dess Egenskaper|journal=Kongliga Vetenskaps Academiens Handlingar [Proceedings of the Royal Scientific Academy]|date=1774|volume=35|pages=89–116, 177–94|url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015039452910;view=1up;seq=99|trans-title=On braunstein [i.e., pyrolusite, manganese dioxide], or magnesia, and its properties|language=sv|access-date=2018-02-19|archive-date=2020-04-23|archive-url=https://web.archive.org/web/20200423132126/https://babel.hathitrust.org/cgi/pt?id=mdp.39015039452910;view=1up;seq=99|url-status=live}} [https://babel.hathitrust.org/cgi/pt?id=mdp.39015039452910;view=1up;seq=103 In section 6 on pp. 93–94 of his paper] {{Webarchive|url=https://web.archive.org/web/20211218003341/https://babel.hathitrust.org/cgi/pt?id=mdp.39015039452910;view=1up;seq=103 |date=2021-12-18 }}, Scheele described how chlorine was produced when a mixture of hydrochloric acid and manganese dioxide (''Brunsten'') was heated: ''"6) (a) På 1/2 uns fint rifven Brunsten slogs 1 uns ren Spiritus salis. ... samt lukten fo̊rsvunnen."'' ( 6) (a) On one half ounce of finely ground Braunstein [pyrolusite] was poured one ounce of pure ''spiritus salis'' [spirit of salt, hydrogen chloride]. After this mixture had been standing in the cold for one hour, the acid had assumed a dark brown colour. One part of this solution was poured into a glass, which was placed over the fire. The solution gave off an odour like warm ''aqua regia'' and after one quarter's hour duration, it was as clear and colourless as water, and the smell had disappeared.) For an English translation of the relevant passages of this article, see: ''The Early History of Chlorine : Papers by Carl Wilhelm Scheele (1774), C. L. Berthollet (1785), Guyton de Morveau (1787), J. L. Gay-Lussac and L. J. Thenard (1809)'' (Edinburgh, Scotland: Alembic Club, 1912), [https://babel.hathitrust.org/cgi/pt?id=coo.31924012394379;view=1up;seq=9 pp. 5–10.] {{Webarchive|url=https://web.archive.org/web/20211218003427/https://babel.hathitrust.org/cgi/pt?id=coo.31924012394379;view=1up;seq=9 |date=2021-12-18 }}</ref><ref name="krogt">{{cite web |url=http://elements.vanderkrogt.net/element.php?sym=Cl |title=17 Chlorine |publisher=Elements.vanderkrogt.net |access-date=2008-09-12 |url-status=dead |archive-url=https://web.archive.org/web/20100123003013/http://elements.vanderkrogt.net/element.php?sym=Cl |archive-date=2010-01-23 }}</ref> Scheele produced chlorine by reacting [[Manganese dioxide|MnO<sub>2</sub>]] (as the mineral [[pyrolusite]]) with HCl:<ref name="Greenwood789" />

:4 HCl + MnO<sub>2</sub> → MnCl<sub>2</sub> + 2 H<sub>2</sub>O + Cl<sub>2</sub>

Scheele observed several of the properties of chlorine: the bleaching effect on [[Litmus test (chemistry)|litmus]], the deadly effect on insects, the yellow-green colour, and the smell similar to [[aqua regia]].<ref name="Greenwood792">{{harvnb|Greenwood|Earnshaw|1997|pp=792–93}}</ref> He called it "''dephlogisticated muriatic acid air''" since it is a gas (then called "airs") and it came from [[hydrochloric acid]] (then known as "muriatic acid").<ref name="krogt" /> He failed to establish chlorine as an element.<ref name="krogt" />

Common chemical theory at that time held that an acid is a compound that contains oxygen (remnants of this survive in the German and Dutch names of [[oxygen]]: {{Lang|de|sauerstoff}} or ''{{Lang|nl|zuurstof}}'', both translating into English as ''acid substance''), so a number of chemists, including [[Claude Berthollet]], suggested that Scheele's ''dephlogisticated muriatic acid air'' must be a combination of oxygen and the yet undiscovered element, ''muriaticum''.<ref>{{Cite book|url=https://books.google.com/books?id=34KwmkU4LG0C&pg=PA158|page=158|title=The development of modern chemistry|author=Ihde, Aaron John|publisher=Courier Dover Publications|date=1984|isbn=978-0-486-64235-2|access-date=2020-05-06|archive-date=2023-12-30|archive-url=https://web.archive.org/web/20231230133555/https://books.google.com/books?id=34KwmkU4LG0C&pg=PA158|url-status=live}}</ref><ref name="Weeks">{{cite journal|doi = 10.1021/ed009p1915|title = The discovery of the elements. XVII. The halogen family|date = 1932|last1 = Weeks|first1 = Mary Elvira|author-link1=Mary Elvira Weeks|journal = Journal of Chemical Education|volume = 9|issue = 11|page = 1915|bibcode=1932JChEd...9.1915W}}</ref>

In 1809, [[Joseph Louis Gay-Lussac]] and [[Louis-Jacques Thénard]] tried to decompose ''dephlogisticated muriatic acid air'' by reacting it with charcoal to release the free element ''muriaticum'' (and carbon dioxide).<ref name="krogt" /> They did not succeed and published a report in which they considered the possibility that ''dephlogisticated muriatic acid air'' is an element, but were not convinced.<ref>{{cite journal|last1 = Gay-Lussac|last2 = Thenard|title = Extrait des mémoires lus à l'Institut national, depuis le 7 mars 1808 jusqu'au 27 février 1809.|trans-title = Extracts from memoirs read at the national Institute, from 7 March 1808 to 27 February 1809|journal = Mémoires de Physique et de Chimie de la Société d'Arcueil|volume = 2|pages = 295–358|date = 1809|url = https://books.google.com/books?id=hnJKAAAAYAAJ&pg=PA295|access-date = 24 February 2018|archive-date = 30 December 2023|archive-url = https://web.archive.org/web/20231230133512/https://books.google.com/books?id=hnJKAAAAYAAJ&pg=PA295#v=onepage&q&f=false|url-status = live}} See: §
''De la nature et des propriétés de l'acide muriatique et de l'acide muriatique oxigéné'' (On the nature and properties of muriatic acid and of oxidized muriatic acid), pp. 339–58. From pp. 357–58: ''"Le gaz muriatique oxigéné n'est pas, en effect, décomposé ... comme un corps composé."'' ("In fact, oxygenated muriatic acid is not decomposed by charcoal, and it might be supposed, from this fact and those that are communicated in this Memoir, that this gas is a simple body. The phenomena that it presents can be explained well enough on this hypothesis; we shall not seek to defend it, however, as it appears to us that they are still better explained by regarding oxygenated muriatic acid as a compound body.") For a full English translation of this section, see: [http://web.lemoyne.edu/~giunta/thenard.html Joseph Louis Gay-Lussac and Louis Jacques Thénard, "On the nature and the properties of muriatic acid and of oxygenated muriatic acid" (Lemoyne College, Syracuse, New York)] {{Webarchive|url=https://web.archive.org/web/20080725061430/http://web.lemoyne.edu/~giunta/thenard.html |date=2008-07-25 }}</ref>

In 1810, [[Sir Humphry Davy]] tried the same experiment again, and concluded that the substance was an element, and not a compound.<ref name="krogt" /> He announced his results to the Royal Society on 15 November that year.<ref name="Greenwood789" /> At that time, he named this new element "chlorine", from the Greek word χλωρος (''chlōros'', "green-yellow"), in reference to its colour.<ref>{{cite journal|last1=Davy|first1=Humphry|title=The Bakerian Lecture. On some of the combinations of oxymuriatic gas and oxygene, and on the chemical relations of these principles, to inflammable bodies|journal=Philosophical Transactions of the Royal Society of London|date=1811|volume=101|pages=1–35|url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015034564297;view=1up;seq=15|bibcode=1811RSPT..101....1D|doi=10.1098/rstl.1811.0001|doi-access=free|access-date=2018-02-19|archive-date=2020-04-23|archive-url=https://web.archive.org/web/20200423032814/https://babel.hathitrust.org/cgi/pt?id=mdp.39015034564297;view=1up;seq=15|url-status=live}} Davy named chlorine on [https://babel.hathitrust.org/cgi/pt?id=mdp.39015034564297;view=1up;seq=46 p. 32:] {{Webarchive|url=https://web.archive.org/web/20211218003415/https://babel.hathitrust.org/cgi/pt?id=mdp.39015034564297;view=1up;seq=46 |date=2021-12-18 }} "After consulting some of the most eminent chemical philosophers in this country, it has been judged most proper to suggest a name founded upon one of its obvious and characteristic properties – its colour, and to call it ''Chlorine'', or ''Chloric'' gas.* *From χλωρος."</ref> The name "[[halogen]]", meaning "salt producer", was originally used for chlorine in 1811 by [[Johann Salomo Christoph Schweigger]].<ref>{{cite journal|last1=Schweigger|first1=J.S.C.|title=Nachschreiben des Herausgebers, die neue Nomenclatur betreffend|journal=Journal für Chemie und Physik|date=1811|volume=3|issue=2|pages=249–55|url=https://babel.hathitrust.org/cgi/pt?id=njp.32101076802287;view=1up;seq=295|trans-title=Postscript of the editor concerning the new nomenclature|language=de|access-date=2018-02-19|archive-date=2020-04-23|archive-url=https://web.archive.org/web/20200423132157/https://babel.hathitrust.org/cgi/pt?id=njp.32101076802287;view=1up;seq=295|url-status=live}} On p. 251, Schweigger proposed the word "halogen": ''"Man sage dafür lieber mit richter Wortbildung ''Halogen'' (da schon in der Mineralogie durch ''Werner's'' Halit-Geschlecht dieses Wort nicht fremd ist) von αλς ''Salz'' und dem alten γενειν (dorisch γενεν) ''zeugen''."'' (One should say instead, with proper morphology, "halogen" (this word is not strange since [it's] already in mineralogy via Werner's "halite" species) from αλς [als] "salt" and the old γενειν [genein] (Doric γενεν) "to beget".)</ref> This term was later used as a generic term to describe all the elements in the chlorine family (fluorine, bromine, iodine), after a suggestion by [[Jöns Jakob Berzelius]] in 1826.<ref>In 1826, Berzelius coined the terms ''Saltbildare'' (salt-formers) and ''Corpora Halogenia'' (salt-making substances) for the elements chlorine, iodine, and fluorine. See: {{cite journal|last1=Berzelius|first1=Jacob|title=Årsberättelser om Framstegen i Physik och Chemie|journal=Arsb. Vetensk. Framsteg|trans-title=Annual Report on Progress in Physics and Chemistry|date=1826|publisher=P.A. Norstedt & Söner|location=Stockholm, Sweden|volume=6|page=187|url=https://babel.hathitrust.org/cgi/pt?id=hvd.32044092556919;view=1up;seq=195|language=sv|access-date=2018-02-19|archive-date=2020-04-23|archive-url=https://web.archive.org/web/20200423132254/https://babel.hathitrust.org/cgi/pt?id=hvd.32044092556919;view=1up;seq=195|url-status=live}} From p. 187: ''"De förre af dessa, d. ä. ''de electronegativa'', dela sig i tre klasser: 1) den första innehåller kroppar, som förenade med de electropositiva, omedelbart frambringa salter, hvilka jag derför kallar ''Saltbildare'' (Corpora Halogenia). Desse utgöras af chlor, iod och fluor *)."'' (The first of them [i.e., elements], i.e., the electronegative [ones], are divided into three classes: 1) The first includes substances which, [when] united with electropositive [elements], immediately produce salts, and which I therefore name "salt-formers" (salt-producing substances). These are chlorine, iodine, and fluorine *).)</ref><ref>{{Cite journal|title=J. S. C. Schweigger: His Romanticism and His Crystal Electrical Theory of Matter|author=Snelders, H. A. M.|journal=Isis|volume=62|issue=3 |pages=328–38|date=1971| doi=10.1086/350763| jstor=229946|s2cid=170337569}}</ref> In 1823, [[Michael Faraday]] liquefied chlorine for the first time,<ref>{{cite journal|last1=Faraday|first1=M.|title=On fluid chlorine|journal=Philosophical Transactions of the Royal Society of London|date=1823|volume=113|pages=160–64|url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015034564487;view=1up;seq=244|bibcode=1823RSPT..113..160F|doi=10.1098/rstl.1823.0016|doi-access=free|access-date=2018-02-19|archive-date=2020-04-23|archive-url=https://web.archive.org/web/20200423053126/https://babel.hathitrust.org/cgi/pt?id=mdp.39015034564487;view=1up;seq=244|url-status=live}}</ref><ref>{{cite web |url=http://www.aps.org/publications/apsnews/200108/history.cfm |title=This Month in Physics History September 4, 1821 and August 29, 1831: Faraday and Electromagnetism |editor=Chodos, Alan |publisher=American Physical Society |access-date=2010-05-08 |url-status=dead |archive-url=https://web.archive.org/web/20100615142343/http://aps.org/publications/apsnews/200108/history.cfm |archive-date=June 15, 2010 }}</ref><ref>{{cite web |url=http://www-history.mcs.st-andrews.ac.uk/Biographies/Faraday.html |author=O'Connor J. J. |author2=Robertson E. F. |work=School of Mathematics and Statistics, University of St Andrews, Scotland |title=Michael Faraday |access-date=2010-05-08 |url-status=dead |archive-url=https://web.archive.org/web/20100220051522/http://www-history.mcs.st-andrews.ac.uk/Biographies/Faraday.html |archive-date=2010-02-20 }}</ref> and demonstrated that what was then known as "solid chlorine" had a structure of [[Clathrate hydrate|chlorine hydrate]] (Cl<sub>2</sub>·H<sub>2</sub>O).<ref name="Greenwood789" />