Editing Iridium (section)

== History ==
=== Platinum group ===
[[File:Winged goddess Cdm Paris 392.jpg|thumb|upright|The Greek goddess [[Iris (mythology)|Iris]], after whom iridium was named.|alt=Photo of part of a black vase with brown picture on it: A woman with wings on her back hold an arrow with right hand and gives a jar to a man. A small deer is standing in front of the woman.]]

The discovery of iridium is intertwined with that of platinum and the other metals of the [[platinum group]]. The first European reference to platinum appears in 1557 in the writings of the Italian humanist [[Julius Caesar Scaliger]] as a description of an unknown noble metal found between [[Darién Province|Darién]] and Mexico, "which no fire nor any Spanish artifice has yet been able to [[Liquefaction|liquefy]]".<ref name="weeks">{{cite journal | last=Weeks | first=Mary Elvira | title=The discovery of the elements. VIII. The platinum metals | journal=Journal of Chemical Education | publisher=American Chemical Society (ACS) | volume=9 | issue=6 | year=1932 | issn=0021-9584 | doi=10.1021/ed009p1017 | pages=1017–1034| bibcode=1932JChEd...9.1017W }}{{cite book |title=Discovery of the Elements |url=https://archive.org/details/discoveryofeleme07edunse |url-access=registration |pages=[https://archive.org/details/discoveryofeleme07edunse/page/385 385]–407 |author=Weeks, M. E. |date=1968 |edition=7th |publisher=Journal of Chemical Education |isbn=978-0-8486-8579-9 |oclc=23991202}}</ref> From their first encounters with platinum, the Spanish generally saw the metal as a kind of [[impurity]] in gold, and it was treated as such. It was often simply thrown away, and there was an official decree forbidding the [[adulteration]] of gold with platinum impurities.<ref name="history">{{cite book |title=A History of Platinum and its Allied Metals |pages=7–8 |author=Donald McDonald, Leslie B. Hunt |date=1982 |publisher=Johnson Matthey Plc |isbn=978-0-905118-83-3}}</ref>
[[File:Platinum symbol.svg|thumb|left|upright=0.4|alt=A left-pointing crescent, tangent on its right to a circle containing at its center a solid circular dot|This [[alchemical symbol]] for platinum was made by joining the symbols of silver (moon) and gold (sun).]]
[[File:Almirante Antonio de Ulloa.jpg|thumb|[[Antonio de Ulloa]] is credited in European history with the discovery of platinum.]]

In 1735, [[Antonio de Ulloa]] and [[Jorge Juan y Santacilia]] saw Native Americans mining platinum while the [[Spaniards]] were travelling through [[Colombia]] and [[Peru]] for eight years. Ulloa and Juan found mines with the whitish metal [[Chicken nugget|nuggets]] and took them home to Spain. Ulloa returned to Spain and established the first [[mineralogy]] lab in Spain and was the first to systematically study platinum, which was in 1748. His historical account of the expedition included a description of platinum as being neither [[Separation process|separable]] nor [[calcination|calcinable]]. Ulloa also anticipated the discovery of platinum mines. After publishing the report in 1748, Ulloa did not continue to investigate the new metal. In 1758, he was sent to superintend [[Mercury (element)|mercury]] mining operations in [[Huancavelica]].<ref name="weeks" />

In 1741, [[Charles Wood (metallurgist)|Charles Wood]],<ref>{{cite book |url=https://books.google.com/books?id=525bAAAAQAAJ&pg=PP7 |page=52 |title=The literary life of William Brownrigg. To which are added an account of the coal mines near Whitehaven: And Observations on the means of preventing epidemic fevers |last1=Dixon |first1=Joshua |last2=Brownrigg |first2=William |date=1801 |url-status=live |archive-url=https://web.archive.org/web/20170324090058/https://books.google.com/books?id=525bAAAAQAAJ&pg=PP7 |archive-date=24 March 2017 |df=dmy-all}}</ref><!--https://books.google.com/books?id=S1lFAAAAcAAJ&pg=PA672--> a British [[metallurgy|metallurgist]], found various samples of Colombian platinum in Jamaica, which he sent to [[William Brownrigg]] for further investigation.

In 1750, after studying the platinum sent to him by Wood, Brownrigg presented a detailed account of the metal to the [[Royal Society]], stating that he had seen no mention of it in any previous accounts of known minerals.<ref>{{cite journal |pages = 584–596 |doi = 10.1098/rstl.1749.0110 |title = Several Papers concerning a New Semi-Metal, Called Platina; Communicated to the Royal Society by Mr. Wm. Watson F. R. S |date = 1749 |last1 = Watson |first1 = Wm |last2 = Brownrigg |first2 = William |journal = Philosophical Transactions |volume = 46 |issue = 491–496 |df = dmy-all |bibcode = 1749RSPT...46..584W |s2cid = 186213277 |doi-access = free }}</ref> Brownrigg also made note of platinum's extremely high melting point and refractory metal-like behaviour toward [[borax]]. Other chemists across Europe soon began studying platinum, including [[Andreas Sigismund Marggraf]],<ref>{{cite book |url=https://books.google.com/books?id=GWNQAAAAcAAJ |title=Versuche mit dem neuen mineralischen Körper Platina del pinto genannt |last1=Marggraf |first1=Andreas Sigismund |date=1760 |url-status=live |archive-url=https://web.archive.org/web/20170324173956/https://books.google.com/books?id=GWNQAAAAcAAJ |archive-date=24 March 2017 |df=dmy-all}}</ref> [[Torbern Bergman]], [[Jöns Jakob Berzelius]],<!--http://www.google.de/url?sa=t&rct=j&q=pmr-v23-i4-155-156&source=web&cd=4&ved=0CFoQFjAD&url=http%3A%2F%2Fwww.platinummetalsreview.com%2Fpdf%2Fpmr-v23-i4-155-156.pdf&ei=FxWTT_6YOoOLswaKy7XeBA&usg=AFQjCNFn8__okV3fK4xcNSg1bQ-Nm_NZHg--> [[William Lewis (scientist)|William Lewis]],<!--http://www.google.de/url?sa=t&rct=j&q=platina+William+Lewis&source=web&cd=1&ved=0CC4QFjAA&url=http%3A%2F%2Fwww.platinummetalsreview.com%2Fpdf%2Fpmr-v7-i2-066-069.pdf&ei=hhWTT4-YNozLsgb14LGLBA&usg=AFQjCNHCECiLbEjXypnkLTujKyMs47FANQ{{cite journal| title=The Platinum of New Granada: Mining and Metallurgy in the Spanish Colonial Empire| author=McDonald, M.| journal=Platinum Metals Review| volume=3| issue=4| date=1959| pages=140–145| url=http://www.platinummetalsreview.com/dynamic/article/view/pmr-v3-i4-140-145}}{cite journal| title=The So-Called 'Platinum' Inclusions in Egyptian Goldwork| first=J. M.| last=Ogden| journal=The Journal of Egyptian Archaeology| volume=62| date=1976| pages=138–144| jstor=3856354| doi=10.2307/3856354}}</ref> and by South American cultures<ref name="preCol">{{cite journal| journal=Platinum Metals Review| date=1980| volume=24| issue=21| pages=70–79| title=The Powder Metallurgy of Platinum| first=J. C.| last=Chaston |url=http://www.technology.matthey.com/pdf/pmr-v24-i2-070-079.pdf}}{{cite book| author=Juan, J.| author2=de Ulloa, A.| date=1748| title=Relación histórica del viage a la América Meridional| page=606| language=es| url=https://books.google.com/books?id=BdSGz0Ea7h8C&| series=Primera parte, tomo secondo}}--> and [[Pierre Macquer]]. In 1752, [[Henrik Teofilus Scheffer|Henrik Scheffer]] published a detailed scientific description of the metal, which he referred to as "white gold", including an account of how he succeeded in fusing platinum ore with the aid of [[arsenic]]. Scheffer described platinum as being less [[pliable]] than gold, but with similar resistance to [[corrosion]].<ref name="weeks" />

=== Discovery ===
[[Chemist]]s who studied platinum [[Dissolution (chemistry)|dissolved]] it in [[aqua regia]] (a mixture of [[hydrochloric acid|hydrochloric]] and [[nitric acid]]s) to create [[Solubility|soluble]] salts. They always observed a small amount of a dark, [[Solubility|insoluble]] residue.<ref name="hunt" /> [[Joseph Louis Proust]] thought that the residue was [[graphite]].<ref name="hunt" /> The French chemists [[Victor Collet-Descotils]], [[Antoine François, comte de Fourcroy]], and [[Louis Nicolas Vauquelin]] also observed the black residue in 1803, but did not obtain enough for further experiments.<ref name="hunt" />

In 1803 British scientist [[Smithson Tennant]] (1761–1815) analyzed the insoluble residue and concluded that it must contain a new metal. Vauquelin treated the powder alternately with [[alkali]] and acids<ref name="Emsley" /> and obtained a volatile new oxide, which he believed to be of this new metal—which he named ''[[Osmium|ptene]]'', from the Greek word {{lang|el|πτηνός}} ''ptēnós'', "[[wing]]ed".<ref>{{cite book |title=A System of Chemistry of Inorganic Bodies |url=https://archive.org/details/asystemchemistr07thomgoog |author=Thomson, T. |author-link=Thomas Thomson (chemist) |publisher=Baldwin & Cradock, London; and William Blackwood, Edinburgh |date=1831 |volume=1 |page=[https://archive.org/details/in.ernet.dli.2015.32266/page/n721/mode/2up 693]}}</ref><ref name="griffith">{{cite journal |url=http://www.technology.matthey.com/article/48/4/182-189/ |title=Bicentenary of Four Platinum Group Metals. Part II: Osmium and iridium – events surrounding their discoveries |author=Griffith, W. P. |journal=Platinum Metals Review |volume=48 |issue=4 |date=2004 |pages=182–189 |doi=10.1595/147106704x4844|doi-access=free }}</ref> Tennant, who had the advantage of a much greater amount of residue, continued his research and identified the two previously undiscovered elements in the black residue, iridium and [[osmium]].<ref name="hunt" /><ref name="Emsley" /> He obtained dark red crystals (probably of {{chem|Na|2|[IrCl|6}}]·''n''{{chem|H|2|O}}) by a sequence of reactions with [[sodium hydroxide]] and [[hydrochloric acid]].<ref name="griffith" /> He named iridium after [[Iris (mythology)|Iris]] ({{lang|el|Ἶρις}}), the Greek winged goddess of the [[rainbow]] and the messenger of the [[Twelve Olympians|Olympian gods]], because many of the [[Salt (chemistry)|salts]] he obtained were strongly colored.{{efn|''Iridium'' literally means "of rainbows".}}<ref>{{cite book |title=Discovery of the Elements |url=https://archive.org/details/discoveryofeleme0000week |url-access=registration |pages=[https://archive.org/details/discoveryofeleme0000week/page/414 414–418] |author=Weeks, M. E. |date=1968 |edition=7th |publisher=Journal of Chemical Education |isbn=978-0-8486-8579-9 |oclc=23991202}}</ref> Discovery of the new elements was documented in a letter to the [[Royal Society]] on June 21, 1804.<ref name="hunt"/><ref>{{cite journal |title=On Two Metals, Found in the Black Powder Remaining after the Solution of Platina |first=S. |last=Tennant |journal=Philosophical Transactions of the Royal Society of London |volume=94 |date=1804 |pages=411–418 |jstor=107152 |doi=10.1098/rstl.1804.0018 |url=https://zenodo.org/record/1432312 |doi-access=free}}</ref>

=== Metalworking and applications ===
British scientist [[John George Children]] was the first to melt a sample of iridium in 1813 with the aid of "the greatest galvanic battery<!-- No page for "Galvanic Battery" --> that has ever been constructed" (at that time).<ref name="hunt" /> The first to obtain high-purity iridium was [[Robert Hare (chemist)|Robert Hare]] in 1842. He found it had a density of around {{cvt|21.8|g/cm3}} and noted the metal is nearly [[Ductility|immalleable]] and very hard. The first melting in appreciable quantity was done by [[Henri Sainte-Claire Deville]] and [[Jules Henri Debray]] in 1860. They required burning more than {{convert|300|L|USgal}} of pure {{chem|O|2}} and {{chem|H|2}} gas for each {{convert|1|kg}} of iridium.<ref name="hunt" />

These extreme difficulties in melting the metal limited the possibilities for handling iridium. [[John Isaac Hawkins]] was looking to obtain a fine and hard point for [[fountain pen]] [[Nib (pen)|nibs]], and in 1834 managed to create an iridium-pointed gold pen. In 1880, [[John Holland (pen maker)|John Holland]] and [[William Lofland Dudley]] were able to melt iridium by adding [[phosphorus]] and patented the process in the United States; British company [[Johnson Matthey]] later stated they had been using a similar process since 1837 and had already presented fused iridium at a number of [[World's fair|World Fairs]].<ref name="hunt" /> The first use of an [[alloy]] of iridium with [[ruthenium]] in [[thermocouple]]s was made by Otto Feussner<!-- No page for "Otto Feussner"
 --> in 1933. These allowed for the measurement of high temperatures in air up to {{convert|2000|C}}.<ref name="hunt" />

In [[Munich]], Germany in 1957 [[Rudolf Mössbauer]], in what has been called one of the "landmark experiments in twentieth-century physics",<ref>{{cite book |pages=179–190 |title=Landmark Experiments in Twentieth Century Physics |author=Trigg, G. L. |publisher=Courier Dover Publications |isbn=978-0-486-28526-9 |date=1995 |oclc=31409781 |chapter=Recoilless Emission and Absorption of Radiation |url=https://books.google.com/books?id=YOQ9fi5yQ4sC}}</ref> discovered the resonant and [[Atomic Recoil|recoil]]-free emission and absorption of [[gamma ray]]s by [[atom]]s in a solid metal sample containing only <sup>191</sup>Ir.<ref>{{cite journal |first=R. L. |last=Mössbauer |s2cid=121129342 |author-link=Rudolf Mössbauer |title=Gammastrahlung in Ir<sup>191</sup> |journal=Zeitschrift für Physik A |volume=151 |issue=2 |pages=124–143 |date=1958 |language=de |doi=10.1007/BF01344210 |bibcode=1958ZPhy..151..124M}}</ref> This phenomenon, known as the [[Mössbauer effect]] resulted in the awarding of the [[Nobel Prize in Physics]] in 1961, at the age 32, just three years after he published his discovery.<ref>{{cite book |title=Nobel Lectures, Physics 1942–1962 |publisher=Elsevier |date=1964 |chapter=The Nobel Prize in Physics 1961: presentation speech |first=I. |last=Waller |chapter-url=http://nobelprize.org/nobel_prizes/physics/laureates/1961/press.html}}</ref>