The discovery of osmium.

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Osmium is a metallic chemical element with the symbol Os, atomic number 76 and atomic weight 190.23. It is a very hard, lustrous bluish-white metal with a close-packed hexagonal crystalline structure. Osmium is used largely for the production of hard alloys for use in fountain pen points, phonograph needles and instrument bearings. Osmium tetroxide is used in microscopy as a stain, in fingerprint detection and as a catalyst[1].


The English chemist Smithson Tennant (1761-1815) discovered[2] osmium in 1804 after experimenting on the residue that remains when aqua regia (nitric acid hydrochloride) is used to dissolve platinum ore. The residue consists of many metals found in the ore. Tennant filtered the residue and heated it strongly with pure alkali in a silver crucible. He then used an acid and distilled the solution to obtain the oxide of this new metal. Here is a photograph[3] of high-purity osmium:

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No portrait of Smithson Tennant could be found.

  2. gbs_navlinks_s, pages 220-221.
  3. Collection/dp/B071JQ83V4