Editing Metre Convention (section)

=== The 1874 metre-alloy ===
[[File:Metre alloy.jpg|thumb|Preparing the first metre-alloy in May 1874, at the Conservatoire des Arts et Métiers, Paris]]
On 6 May 1873 during the 6th session of the French section of the Metre Commission, [[Henri Étienne Sainte-Claire Deville]] cast a 20-kilogram platinum-iridium ingot from Matthey in his laboratory at the [[École normale supérieure (Paris)]]. On 13 May 1874, 250 kilograms of platinum-iridium to be used for several national prototypes of the metre was cast at the [[Conservatoire national des arts et métiers]].<ref name="BIPM-150" /> When a conflict broke out regarding the presence of impurities in the metre-alloy of 1874, a member of the Preparatory Committee since 1870 and president of the Permanent Committee of the International Metre Commission,<ref>{{Cite book |last=Bigourdan |first=Guillaume |url=https://archive.org/details/lesystmemtri00bigo/page/n345/mode/2up |title=Le système métrique des poids et mesures ; son établissement et sa propagation graduelle, avec l'histoire des opérations qui ont servi à déterminer le mètre et le kilogramme |date=1901 |publisher=Paris : Gauthier-Villars |others=University of Ottawa |pages=313}}</ref> [[Carlos Ibáñez e Ibáñez de Ibero]] intervened with the [[French Academy of Sciences]] to rally France to the project to create an International Bureau of Weights and Measures equipped with the scientific means necessary to redefine the units of the [[metric system]] according to the progress of sciences.<ref name="Pérard-19572">{{Cite web |last=Pérard |first=Albert |date=1957 |title=Carlos Ibáñez e Ibáñez de Ibero (14 avril 1825 – 29 janvier 1891), par Albert Pérard (inauguration d'un monument élevé à sa mémoire) |url=https://www.academie-sciences.fr/pdf/eloges/ibanez_notice.pdf |website=Institut de France – Académie des sciences |pages=26–28}}</ref> In fact, the chemical analysis of the alloy produced in 1874 by the French section revealed contamination by [[ruthenium]] and [[iron]] which led the [[General Conference on Weights and Measures|International Committee for Weights and Measures]] to reject, in 1877, the prototypes produced by the French section from the 1874 alloy. It also seemed at the time that the production of prototypes with an X profile was only possible through the [[extrusion]] process, which resulted in iron contamination. However, it soon turned out that the prototypes designed by [[Henri Tresca]] could be produced by [[Milling (machining)|milling]].<ref name="Quinn-20122">{{Cite book |last=Quinn |first=T. J. |title=From artefacts to atoms: the BIPM and the search for ultimate measurement standards |date=2012 |publisher=Oxford University Press |isbn=978-0-19-990991-9 |location=Oxford |pages=3-10, 14, 90-91, 56-57, 72, 108, 56-57 |oclc=861693071}}</ref>