Editing Chlorine (section)

==History==
The most common compound of chlorine, sodium chloride, has been known since ancient times; archaeologists have found evidence that [[rock salt]] was used as early as 3000&nbsp;BC and [[brine]] as early as 6000&nbsp;BC.<ref>{{cite web |title=The earliest salt production in the world: an early Neolithic exploitation in Poiana Slatinei-Lunca, Romania |url=https://antiquity.ac.uk/ProjGall/weller/ |url-status=dead |archive-url=https://web.archive.org/web/20110430145935/http://antiquity.ac.uk/ProjGall/weller/ |archive-date=April 30, 2011 |access-date=2008-07-10}}</ref>

===Early discoveries===
Around 900, the authors of the Arabic writings attributed to [[Jabir ibn Hayyan]] (Latin: Geber) and the Persian physician and alchemist [[Abu Bakr al-Razi]] ({{circa}} 865–925, Latin: Rhazes) were experimenting with [[sal ammoniac]] ([[ammonium chloride]]), which when it was distilled together with [[vitriol]] (hydrated [[sulfates]] of various metals) produced [[hydrogen chloride]].<ref>{{Cite book|last=Kraus|first=Paul|author-link=Paul Kraus (Arabist)|year=1942–1943|title=Jâbir ibn Hayyân: Contribution à l'histoire des idées scientifiques dans l'Islam. I. Le corpus des écrits jâbiriens. II. Jâbir et la science grecque|publisher=[[Institut Français d'Archéologie Orientale]]|location=Cairo|oclc=468740510|isbn=978-3487091150}} vol. II, pp. 41–42; {{cite book|last=Multhauf|first=Robert P.|author-link=Robert P. Multhauf|year=1966|title=The Origins of Chemistry|location=London|publisher=Oldbourne|isbn=}} pp. 141–42.</ref> However, it appears that in these early experiments with chloride [[Salt (chemistry)|salts]], the gaseous products were discarded, and hydrogen chloride may have been produced many times before it was discovered that it can be put to chemical use.<ref>{{harvnb|Multhauf|1966|loc=p. 142, note 79}}.</ref> One of the first such uses was the synthesis of [[mercury(II) chloride]] (corrosive sublimate), whose production from the heating of [[mercury (element)|mercury]] either with [[alum]] and ammonium chloride or with vitriol and sodium chloride was first described in the ''De aluminibus et salibus'' ("On Alums and Salts", an eleventh- or twelfth century Arabic text falsely attributed to Abu Bakr al-Razi and [[Latin translations of the 12th century|translated into Latin in the second half of the twelfth century]] by [[Gerard of Cremona]], 1144–1187).<ref>{{harvnb|Multhauf|1966|pp=160–163}}.</ref> Another important development was the discovery by [[pseudo-Geber]] (in the ''De inventione veritatis'', "On the Discovery of Truth", after c.&nbsp;1300) that by adding ammonium chloride to [[nitric acid]], a strong solvent capable of dissolving gold (i.e., ''[[aqua regia]]'') could be produced.<ref>{{Cite journal|last1=Karpenko|first1=Vladimír|last2=Norris|first2=John A.|year=2002|title=Vitriol in the History of Chemistry|journal=Chemické listy|volume=96|issue=12|pages=997–1005|url=http://www.chemicke-listy.cz/ojs3/index.php/chemicke-listy/article/view/2266|access-date=2021-02-09|archive-date=2021-12-18|archive-url=https://web.archive.org/web/20211218003227/http://www.chemicke-listy.cz/ojs3/index.php/chemicke-listy/article/view/2266|url-status=live}} p. 1002.</ref> Although ''aqua regia'' is an unstable mixture that continually gives off fumes containing free chlorine gas, this chlorine gas appears to have been ignored until c.&nbsp;1630, when its nature as a separate gaseous substance was recognised by the [[Duchy of Brabant|Brabantian]] chemist and physician [[Jan Baptist van Helmont]].<ref name="Greenwood789">{{harvnb|Greenwood|Earnshaw|1997|pp=789–92}}</ref><ref group=en>{{cite book|last1=van Helmont|first1=Joannis Baptistae|title=Opera omnia [All Works]|date=1682|publisher=Johann Just Erythropel|location=Frankfurt-am-Main, (Germany)|url=https://books.google.com/books?id=Qy5AAAAAcAAJ&pg=PP5|language=la}} From ''"Complexionum atque mistionum elementalium figmentum."'' (Formation of combinations and of mixtures of elements), §37, [https://books.google.com/books?id=Qy5AAAAAcAAJ&pg=PA105 p. 105:] {{Webarchive|url=https://web.archive.org/web/20231230133537/https://books.google.com/books?id=Qy5AAAAAcAAJ&pg=PA105#v=onepage&q&f=false |date=2023-12-30 }} ''"Accipe salis petrae, vitrioli, & alumnis partes aequas: exsiccato singula, & connexis simul, distilla aquam. Quae nil aliud est, quam merum sal volatile. Hujus accipe uncias quatuor, salis armeniaci unciam junge, in forti vitro, alembico, per caementum (ex cera, colophonia, & vitri pulverre) calidissime affusum, firmato; mox, etiam in frigore, Gas excitatur, & vas, utut forte, dissilit cum fragore."'' (Take equal parts of saltpeter [i.e., sodium nitrate], vitriol [i.e., concentrated sulfuric acid], and alum: dry each and combine simultaneously; distill off the water [i.e., liquid]. That [distillate] is nothing else than pure volatile salt [i.e., spirit of nitre, nitric acid]. Take four ounces of this [viz, nitric acid], add one ounce of Armenian salt [i.e., ammonium chloride], [place it] in a strong glass alembic sealed by cement ([made] from wax, rosin, and powdered glass) [that has been] poured very hot; soon, even in the cold, gas is stimulated, and the vessel, however strong, bursts into fragments.) From ''"De Flatibus"'' (On gases), [https://books.google.com/books?id=Qy5AAAAAcAAJ&pg=PA408 p. 408] {{Webarchive|url=https://web.archive.org/web/20231230133615/https://books.google.com/books?id=Qy5AAAAAcAAJ&pg=PA408#v=onepage&q&f=false |date=2023-12-30 }}: ''"Sal armeniacus enim, & aqua chrysulca, quae singula per se distillari, possunt, & pati calorem: sin autem jungantur, & intepescant, non possunt non, quin statim in Gas sylvestre, sive incoercibilem flatum transmutentur."'' (Truly Armenian salt [i.e., ammonium chloride] and nitric acid, each of which can be distilled by itself, and submitted to heat; but if, on the other hand, they be combined and become warm, they cannot but be changed immediately into carbon dioxide [note: van Helmont's identification of the gas is mistaken] or an incondensable gas.)<br>
See also:
* [https://www.encyclopedia.com/people/science-and-technology/chemistry-biographies/johannes-joan-baptista-van-helmont Helmont, Johannes (Joan) Baptista Van, Encyclopedia.Com] {{Webarchive|url=https://web.archive.org/web/20211218003254/https://www.encyclopedia.com/people/science-and-technology/chemistry-biographies/johannes-joan-baptista-van-helmont |date=2021-12-18 }}: "Others were chlorine gas from the reaction of nitric acid and sal ammoniac; ... "
* Wisniak, Jaime (2009) "Carl Wilhelm Scheele," ''Revista CENIC Ciencias Químicas'', '''40''' (3): 165–73; see p. 168: "Early in the seventeenth century Johannes Baptiste van Helmont (1579–1644) mentioned that when sal marin (sodium chloride) or sal ammoniacus and aqua chrysulca (nitric acid) were mixed together, a flatus incoercible (non-condensable gas) was evolved."</ref>
[[File:PSM V31 D740 Carl Wilhelm Scheele.jpg|thumb|left|upright=0.65|[[Carl Wilhelm Scheele]], discoverer of chlorine]]

===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" />

===Later uses===
Chlorine gas was first used by French chemist [[Claude Louis Berthollet|Claude Berthollet]] to bleach textiles in 1785.<ref name="encyc">{{cite encyclopedia |encyclopedia=Encyclopædia Britannica |title=Bleaching |url=http://www.1902encyclopedia.com/B/BLE/bleaching.html |access-date=2012-05-02 |edition=9th Edition (1875) and 10th Edition (1902) |url-status=dead |archive-url=https://web.archive.org/web/20120524111017/http://www.1902encyclopedia.com/B/BLE/bleaching.html |archive-date=2012-05-24 }}</ref><ref name="Cotton">{{Cite book| title=The Cotton Industry| last=Aspin| first=Chris| publisher=Shire Publications Ltd| date=1981| isbn=978-0-85263-545-2| page=[https://archive.org/details/cottonindustry0000aspi/page/24 24]| url=https://archive.org/details/cottonindustry0000aspi/page/24}}</ref> Modern bleaches resulted from further work by Berthollet, who first produced [[sodium hypochlorite]] in 1789 in his laboratory in the town of [[Javel - André Citroën (Paris Métro)|Javel]] (now part of [[Paris]], France), by passing chlorine gas through a solution of sodium carbonate. The resulting liquid, known as "{{Lang|fr|Eau de Javel}}" ("[[Javel water]]"), was a weak solution of [[sodium hypochlorite]]. This process was not very efficient, and alternative production methods were sought. Scottish chemist and industrialist [[Charles Tennant]] first produced a solution of [[calcium hypochlorite]] ("chlorinated lime"), then solid calcium hypochlorite (bleaching powder).<ref name="encyc" /> These compounds produced low levels of elemental chlorine and could be more efficiently transported than sodium hypochlorite, which remained as dilute solutions because when purified to eliminate water, it became a dangerously powerful and unstable oxidizer. Near the end of the nineteenth century, E. S. Smith patented a method of sodium hypochlorite production involving electrolysis of [[brine]] to produce [[sodium hydroxide]] and chlorine gas, which then mixed to form sodium hypochlorite.<ref>{{cite web |url=http://www.chm.bris.ac.uk/motm/bleach/bleachh.htm |title=Bleach (Sodium Hypochlorite) |author=Paul May |publisher=University of Bristol |access-date=13 December 2016 |archive-url=https://web.archive.org/web/20161213230407/http://www.chm.bris.ac.uk/motm/bleach/bleachh.htm |archive-date=13 December 2016 |url-status=live}}</ref> This is known as the [[chloralkali process]], first introduced on an industrial scale in 1892, and now the source of most elemental chlorine and sodium hydroxide.<ref name="Greenwood798">{{harvnb|Greenwood|Earnshaw|1997|p=798}}</ref> In 1884 Chemischen Fabrik Griesheim of Germany developed another [[chloralkali process]] which entered commercial production in 1888.<ref>{{cite book|url=https://books.google.com/books?id=OI0fTJhydh4C&q=Chlorine-Alkali+Griesheim+1884&pg=PA220|title=History of Industrial Gases|isbn=978-0-306-47277-0|last1=Almqvist|first1=Ebbe|publisher=Springer Science & Business Media|date=2003|page=220|access-date=2020-10-09|archive-date=2023-12-30|archive-url=https://web.archive.org/web/20231230133537/https://books.google.com/books?id=OI0fTJhydh4C&q=Chlorine-Alkali+Griesheim+1884&pg=PA220#v=snippet&q=Chlorine-Alkali%20Griesheim%201884&f=false|url-status=live}}</ref>

Elemental chlorine solutions dissolved in [[base (chemistry)|chemically basic]] water (sodium and [[calcium hypochlorite]]) were first used as anti-[[putrefaction]] agents and [[disinfectant]]s in the 1820s, in France, long before the establishment of the [[germ theory of disease]]. This practice was pioneered by [[Antoine-Germain Labarraque]], who adapted Berthollet's "Javel water" bleach and other chlorine preparations.<ref name="bouvet">{{cite journal |author=Bouvet, Maurice |language=fr |trans-title=The great pharmacists: Labarraque (1777–1850) |title=Les grands pharmaciens: Labarraque (1777–1850) |journal=Revue d'Histoire de la Pharmacie |date=1950 |volume=38 |issue=128 |pages=97–107 |doi=10.3406/pharm.1950.8662 }}</ref> Elemental chlorine has since served a continuous function in topical [[Antiseptic|antisepsis]] (wound irrigation solutions and the like) and public sanitation, particularly in swimming and drinking water.<ref name="Greenwood792" />

Chlorine gas was first used as a weapon on April 22, 1915, at the [[Second Battle of Ypres]] by the [[German Army (German Empire)|German Army]].<ref>{{cite web|url=http://www.drcordas.com/education/weaponsmassd/Chlorine.pdf |title=Chlorine – History |access-date=2008-07-10 |url-status=dead |archive-url=https://web.archive.org/web/20070221140939/http://www.drcordas.com/education/weaponsmassd/Chlorine.pdf |archive-date=21 February 2007 }}</ref><ref>{{cite web|title = Weaponry: Use of Chlorine Gas Cylinders in World War I|url = http://www.historynet.com/weaponry-use-of-chlorine-gas-cylinders-in-world-war-i.htm|publisher = historynet.com|access-date = 2008-07-10|url-status = live|archive-url = https://web.archive.org/web/20080702044210/http://www.historynet.com/weaponry-use-of-chlorine-gas-cylinders-in-world-war-i.htm|archive-date = 2008-07-02|date = 2006-06-12}}</ref> The effect on the allies was devastating because the existing [[WWI gas mask|gas mask]]s were difficult to deploy and had not been broadly distributed.<ref>{{Cite web
 |author      = Staff
 |date        = 29 July 2004
 |url         = http://www.vac-acc.gc.ca/remembers/sub.cfm?source=history/firstwar/canada/Canada4
 |title       = On the Western Front, Ypres 1915
 |publisher   = Veteran Affairs Canada
 |access-date  = 2008-04-08
 |url-status     = dead
 |archive-url  = https://web.archive.org/web/20081206024237/http://www.vac-acc.gc.ca/remembers/sub.cfm?source=history%2Ffirstwar%2Fcanada%2FCanada4
 |archive-date = 6 December 2008
}}</ref><ref>{{Cite book
 | first=Victor | last=Lefebure |author2=Wilson, Henry
 | title=The Riddle of the Rhine: Chemical Strategy in Peace and War
 | year=2004 | publisher=Kessinger Publishing | isbn=978-1-4179-3546-8 }}</ref>