Incredibly dense, blue metal which oxidizes readily in a powdered/sponge form, but not as a solid ingot/pellet m.p. 3045±30 ºC; 5513±54 ºF b.p. 5027±100 ºC; 9081±180 ºF density 22.57 g/cc; 1409.00 pound/cubic foot	memory peg
	1803 Smithson Tennant, England / independent by N.L. Vauquelin, A.-F. Fourcroy, & H.V. Collet-Descotils, France
	οσμη (osmè) = stench (Greek) named by S. Tennant

William Hyde Wollaston and Smithson Tennant (1761-1815), who had befriended at Cambridge, formed in 1800 a secret partnership to share expenses and income from ventures in commercially production of Platinum (see Platinum).

During their researches into the purification of platinum by dissolution of native platinum ore in aqua regia, a large amount of insoluble black powder remained as a byproduct of this operation. While Wollaston concentrated on the soluble portion and found Palladium (1802), Rhodium (1804). Tennant examined the insoluble residue. In the summer of 1803, Tennant identified two new elements, Osmium (1803) and Iridium (1803). This was documented in the paper he read to the Royal Society on 21 June 1804 (note).

The insoluble, dark residue was melted with alkalis and treated with acid, distilled and then condensed, leading to a greasy liquid, with a strong and peculiar smell, and then to a semi-transparent solid. Tennant showed that this residue contains two metals, Osmium and Iridium. Of this oxide he wrote:

About the same time, in Paris, suspected Hippolyte Victor Collet-Descotils, the existence of a new metal by the black powder formed by the dissolution of native Platinum in aqua regia. In 1803 Antoine-François de Fourcroy and Nicolas-Louis Vauquelin observed this black powder and came to the conclusion that in the insoluble residue a new metal is present.

In his paper for the Royal Society on the 21 June 1804 Tennant mentioned the parallel research in France by Descotils and Vauquelin. Both chemists found Osmium, "But," wrote Tennant, "neither of these chemists have observed that it contains also another metal, different from any hitherto known." This other metal is osmium (Weeks 1968).
According to some authors, Fourcroy and Vauquelin gave the new substance the name of Ptene, from Greek πτηνος (ptènos) = winged (See Iridium).

• Griffith, W.P., Bicentenary of Four Platinum Group Metals, Part II: Osmium and Iridium – events surrounding their discoveries. In: Platinum Metals Review 48, 4 (October 2004): 182-189 (on-line).
• International Platinum Association, Osmium History (on-line).
• Platinum. Gmelins Handbuch der anorganische Chemie, 8. Aufl.; System-Nummer 68 (1951), Pt. A. pp. 12-13.
• Tennant, Smithson, "On two Metals, found in the black powder remaining after the solution of Platina." Philosophical Transactions of the Royal Society of London 95 (1805), 411-418.
• Weeks, Mary Elvira, Discovery of the Elements, comp. rev. by Heny M. Leicester (Easton, Pa.: Journal of Chemical Education, 1968), pp. 414-418.