Editing Chlorine (section)

===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]]