The metal may be obtained from the residues obtained in the separation of osmium from osmiridium.
Chem., 1905, 45, p. 166) by heating the crude metal (obtained by other processes) in a current of oxygen until all the osmium is volatilized as tetroxide.
In the following year he discovered rhodium; and at about the same time Smithson Tennant added two more to the list - iridium and osmium; the former was so named from the changing tints of its oxides (ipcs, rainbow), and the latter from the odour of its oxide (ovµA, smell).
Seubert redetermined this constant for platinum, osmium and iridium; E.
This varies in metals from 594 (lithium) to 22.48 (osmium), and in one and the same species is a function of temperature and of previous physical and mechanical treatment.
In the oxyhydrogen flame silver boils, forming a blue vapour, while platinum volatilizes slowly, and osmium, though infusible, very readily.
OSMIUM [[[symbol]] Os., atomic weight 190.9 (0= 16)], in chemistry, a metallic element, found in platinum ore in small particles, consisting essentially of an alloy of osmium and iridium and known as osmiridium.
The residue so obtained is then powdered and ignited with barium nitrate, which converts the iridium into its oxide and the osmium into barium osmiate.
The barium salt is extracted by water and boiled with nitric acid, when the osmium volatilizes in the form of its tetroxide.
After fusion, the mass is finely powdered and treated with cold dilute hydrochloric acid; and when action has finished, nitric and sulphuric acids are added, the precipitated barium sulphate removed, the liquid distilled and the osmium precipitated as sulphide.
Chem., 1905 (2), 71, p. 45 2) by reducing osmium compounds with hydrazine hydrate in the presence of gum arabic.
Several oxides of osmium are known.
The protoxide, OsO, is obtained as a dark grey insoluble powder when osmium sulphite is heated with sodium carbonate in a current of carbon dioxide.
The sesquioxide, Os203, results on heating osmium with an excess of the tetroxide.
The tetroxide, 0s04, is formed when osmium compounds are heated in air, or with aqua regia, or fused with caustic alkali and nitre.
Osmium dichloride, OsC1 21 is obtained as a dark coloured powder when the metal is heated in a current of chlorine.
The tetrachloride, OsC1 41 is obtained as a dark red sublimate (mixed with the dichloride) when osmium is l}eated in dry chlorine.
Potassium osmichloride, K 2 OsC1 6, is formed when a mixture of osmium and potassium chloride is heated in a current of chlorine, or on adding potassium chloride and alcohol to a solution of the tetroxide in hydrochloric acid.
Iodine has no action on osmium, but on warming the tetroxide with a mixture of potassium iodide and hydrochloric acid a deep emerald green colour is produced, due to the formation of a compound 0s12.2H1; this reaction is a delicate test for osmium (E.
Osmium disulphide, OsS2, is obtained as a dark brown precipitate, insoluble in water, by passing sulphuretted hydrogen into a solution of an osmichloride.
He was a man of more promise than performance, and his chief achievement was the discovery of the elements iridium and osmium, which he found in the residues from the solution of platinum ores (1804).
4 shows the mounting of a Thomson card on its pivot, which in common with the pivots of most other compasses is made of brass, tipped with osmium-iridium, which although very hard can be sharply pointed and does not corrode.
The various improvements in electric illuminants, such as the Nernst oxide lamp, the tantalum and osmium incandescent lamps, and improved forms of arc lamp, enclosed, inverted and flame arcs, are described under Lighting: Electric. Between 1890 and 1900, electric traction advanced rapidly in the United States of America but more slowly in England.