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The blue plaque for Smithson Tennant in Finkle Street, Selby, North Yorkshire. Smithson Tennant FRS (30 November 1761 [1] – 22 February 1815 [2]) was an English chemist.He is best known for his discovery of the elements iridium and osmium, which he found in the residues from the solution of platinum ores in 1803.
The density of osmium is slightly greater than that of iridium; the two are so similar (22.587 versus 22.562 g/cm 3 at 20 °C) that each was at one time considered to be the densest element. Only in the 1990s were measurements made accurately enough (by means of X-ray crystallography) to be certain that osmium is the denser of the two. [11] [15]
Perey discovered it as a decay product of 227 Ac. [177] Francium was the last element to be discovered in nature, rather than synthesized in the lab, although four of the "synthetic" elements that were discovered later (plutonium, neptunium, astatine, and promethium) were eventually found in trace amounts in nature as well. [178]
Iron is a part of some hormones as well. A lack of iron in the body can cause iron deficiency anemia, and an excess of iron in the body can be toxic. [7] Some ruthenium-containing molecules may be used to fight cancer. [8] Normally, however, ruthenium plays no role in the human body. [3] Both osmium and hassium have no known biological roles ...
Early in 1909, Haber discovered that osmium could serve as a catalyst. Later, he established that uranium could also act as a catalyst. [51] Haber also obtained good results with iron, nickel, manganese and calcium. [52] In the chemical equation shown above, the direct reaction is exothermic.
Iridium is extremely brittle, to the point of being hard to weld because the heat-affected zone cracks, but it can be made more ductile by addition of small quantities of titanium and zirconium (0.2% of each apparently works well). [19] The Vickers hardness of pure platinum is 56 HV, whereas platinum with 50% of iridium can reach over 500 HV ...
Auer von Welsbach then started work on development of metal-filament mantles, first with platinum wiring, and then osmium. Osmium is very difficult to work with, but he developed a new method, which mixed osmium oxide powder with rubber or sugar into a paste, which is then squeezed through a nozzle and fired. The paste burns away, leaving a ...
For example, a dagger made of meteoric iron was found in the tomb of Tutankhamun, containing similar proportions of iron, cobalt, and nickel to a meteorite discovered in the area, deposited by an ancient meteor shower. [88] [89] [90] Items that were likely made of iron by Egyptians date from 3000 to 2500 BC. [86]