atomic See also:

• WEIGHT

weight 190.9 See also:

• atomic weight 190.9 OSMIUM [symbol Os. (0= r6)]

OSMIUM [See also:

• SYMBOL (Gr. o-uµ(3oXov, a sign)

symbol Os. (0= r6)]  , in See also:

• CHEMISTRY
• CHEMISTRY (formerly "chymistry"; Gr. xvµela; for derivation see ALCHEMY)

chemistry, a metallic See also:

• ELEMENT (Lat. elementum)

element, found in See also:

• PLATINUM [symbol Pt, atomic weight 145.0 (0=16)]

platinum ore in small particles, consisting essentially of an alloy of See also:

• OSMIUM [symbol Os., atomic weight 190.9 (0= r6)]

osmium and See also:

• IRIDIUM (symbol Ir.; atomic weight 193.1)

iridium and known as osmiridium . It was first obtained in 1803 by See also:

• SMITHSON, HENRIETTA CONSTANCE (1800-1854)
• SMITHSON, JAMES (1765-1829)

Smithson See also:

• TENNANT, CHARLES (1768-1838)
• TENNANT, SMITHSON (1761-1815)
• TENNANT, WILLIAM (1784-1848)

Tennant (Phil . Trans., 1804, 94, p . 411) . It may be prepared from osmiridium by fusing the alloy with See also:

• ZINC

zinc, the zinc being afterwards removed by See also:

• DISTILLATION (from the Lat. distillare, more correctly destillare, to drop or trickle down)

distillation . T e See also:

• RESIDUE (through the French, from the Lat. residuum, a remainder, from residere, to remain)

residue so obtained is then powdered and ignited with bariu nitrate, which converts the iridium into its See also:

• OXIDE

oxide and the osmium into See also:

• BARIUM (symbol Ba, atomic weight 137'37 [0=16])

barium osmiate . The barium See also:

• SALT (a common Teutonic word, cf. Dutch zout, Ger. Salz, Scand. salt; cognate with Gr. &Xs, Lat. sal)
• SALT, SIR TITUS, BART

salt is extracted by See also:

• WATER

water and boiled with nitric See also:

• ACID (from the Lat. root ac-, sharp; acere, to be sour)

acid, when the osmium volatilizes in the See also:

• FORM (Lat. forma)

form of its tetroxide . As an alternative the osmiridium is fused with zinc, the See also:

• REGULUS, MARCUS ATILIUS

regulus treated with hydrochloric acid, and then heated with barium nitrate and barium peroxide . After See also:

• FUSION

fusion, the See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

mass is finely powdered and treated with See also:

• COLD (in O. Eng. cald and ceald, a word coming ultimately from a root cognate with the Lat. gelu, gelidus, and common in the Teutonic languages, which usually have two distinct forms for the substantive and the adjective, cf. Ger. Kolte, kalt, Dutch koude

cold dilute hydrochloric acid; and when See also:

• ACTION

action has finished, nitric and sulphuric acids are added, the precipitated barium sulphate removed, the liquid distilled and the osmium precipitated as sulphide . The sulphide is converted into See also:

• SODIUM [symbol Na, from Lat. natrium; atomic weight 23.00 (0=16)]

sodium osmichloride by fusion with salt, in a current of See also:

• CHLORINE (symbol Cl, atomic weight 35`46 (0=16)

chlorine, the sodium salt transformed into ammonium salt by precipitation with ammonium chloride, and the ammonium salt finally heated strongly (H . Sainte-Claire-Deville and H . J .

Debray, An. See also:

• MIN

min., 1859 [5], 16, 74; see also C . E . Claus, Jour. prakt . Chem., 1862, 85, p . 142; F . See also:

• WOHLER, FRIEDRICH (1800-1882)

Wohler, Pogg . 31, p . 161; E . Leidie and L . Quenessen, See also:

• BULL
• BULL, GEORGE (1634–1710)
• BULL, JOHN (c. 1562–1628)
• BULL, OLE BORNEMANN (18ro-188o)

Bull. See also:

• SOC

soc. aim., 1903 (8), 29, p . 801) . The tetroxide, OsO4, can be easily reduced to the See also:

• METAL
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

metal by dissolving it in hydrochloric acid and adding zinc, See also:

• MERCURY
• MERCURY (MERCU1uus)
• MERCURY (symbol Hg, atomic weight = 2oo)

mercury, or an alkaline formate to the liquid, or by passing its vapour, mixed with See also:

• CARBON (symbol C, atomic weight 12)

carbon dioxide and monoxide, through a red-hot See also:

• PORCELAIN

porcelain See also:

• TUBE (Lat. tuba)

tube .

The metal has a See also:

• BLUE (common in different forms to most European languages)

blue-See also:

• GREY, CHARLES GREY, 2ND EARL (1764-1845)
• GREY, HENRY GREY, 3RD EARL (1802-1894)
• GREY, LADY JANE (1537-1554)
• GREY, SIR EDWARD
• GREY, SIR GEORGE (1812–1898)

grey See also:

• COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour, and may be obtained in the crystalline See also:

• STATE
• STATE, GREAT OFFICERS OF

state by See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution in See also:

• TIN (Lat.- stannum, whence the chemical symbol " Sn "; atomic weight =117.6, 0=16)

tin . Its specific gravity is 21.3-22.48 (Deville and Debray) and its specific See also:

• HEAT (0. E. haktu, which like " hot," Old Eng. hat, is from the Teutonic type haita, hit, to be hot; cf. Ger. hitze, heiss; Dutch, hitte, heet, &c.)

heat is o•03113 (See also:

• REGNAULT, HENRI (1843-1871)
• REGNAULT, HENRI VICTOR (1810-1878)
• REGNAULT, JEAN BAPTISTE (1754-1829)

Regnault) . It can be distilled in the electric See also:

• FURNACE

furnace . In the massive state it is insoluble in all acids, but when freshly precipitated from solutions it dissolves in fuming nitric acid . On fusion with See also:

• CAUSTIC (Gr. rcavvraubs, burning)

caustic potash it yields See also:

• POTASSIUM [symbol K (from kalium), atomic weight 39.114 0=16)]

potassium osmiate . It combines with See also:

• FLUORINE (symbol F, atomic weight 19)

fluorine at See also:

• ROC

roc° C., and when heated with chlorine it forms a mixture of chlorides . A colloidal variety was obtained by A . Gutbier and G . Hofmeier (Jour. prakt . Chem., 1905 (2), 71, p . 452) by reducing osmium compounds with See also:

• HYDRAZINE (DIAMIDOGEN), N2H4

hydrazine See also:

• HYDRATE

hydrate in the presence of See also:

• GUM (Fr. gomme, Lat. gommi, Gr. Kµµ1, possibly a Coptic word; distinguish " gum," the fleshy covering of the base of a tooth, in O. Eng. gbma, palate, cf. Ger. Gaumen, roof of the mouth; the ultimate origin is probably the root gha, to open wide, seen in

gum arabic . Several oxides of osmium are known .

The protoxide, OsO, is obtained as a dark grey insoluble See also:

• POWDER (through O. Fr. puldre, modern poudre, from Lat. pulvis, pulveris, dust)

powder when osmium sulphite is heated with sodium carbonate in a current of carbon dioxide . The sesquioxide, OS20,, results on See also:

• HEATING

heating osmium with an excess of the tetroxide . The dioxide, OsO2, is formed when potassium osmichloride is heated with sodium carbonate in a current of carbon dioxide, or by See also:

• ELECTROLYSIS (formed from Gr. Xbety, to loosen)

electrolysis of a solution of the tetroxide in the presence of See also:

• ALKALI

alkali . It is insoluble in acids and exists in several hydrated forms . The osmiates, corresponding to the unknown trioxide OsO3, are red or See also:

• GREEN, A
• GREEN, ALEXANDER HENRY (1832—1896)
• GREEN, DUFF (1791—1875)
• GREEN, JOHN RICHARD (1837—1883)
• GREEN, MATTHEW (1696-1737)
• GREEN, THOMAS HILL (1836-1882)
• GREEN, VALENTINE (1739–1813)
• GREEN, WILLIAM HENRY (.1825–1900)

green coloured salts; the solutions are only See also:

• STABLE

stable in the presence of excess of caustic alkali; on boiling an aqueous solution of the potassium salt it decomposes readily, forming a See also:

• BLACK
• BLACK, ADAM (1784-1874)
• BLACK, JEREMIAH SULLIVAN (1810–1883)
• BLACK, WILLIAM (1841-1898)

black precipitate of osmic acid, H20s04 . Potassium osmiate, K20sO42H2O, formed when an alkaline solution of the tetroxide is decomposed by See also:

• ALCOHOL

alcohol, or by potassium nitrite, crystallizes in red octahedra . It is stable in dry See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air, but in moist air rapidly decomposes . The tetroxide, OsO4, is formed when osmium compounds are heated in air, or with aqua regia, or fused with caustic alkali and See also:

• NITRE

nitre . It is obtained as a yellowish coloured mass and can be sublimed in the form of needles which melt at 4o° C . It possesses an unpleasant See also:

• SMELL (connected etymologically with " smoulder " and " smoke ")

smell and its vapour is extremely poisonous . It dissolves slowly in water, and the aqueous solution is reduced by most metals with precipitation of osmium . It acts as an oxidizing See also:

• AGENT (from Lat. agere, to act)

agent, liberating See also:

• IODINE (symbol I, atomic weight '26.92)

iodine from potassium iodide, converting alcohol into acetaldehyde, &c .

Osmium dichloride, OsC12, is obtained as a dark coloured powder when the metal is heated in a current of chlorine . Its solution in water is deep blue in colour, but the colour changes rapidly togreen and yellow . The trichloride, OsC18, is only known in solution and is formed by the reducing action of mercury on See also:

• AMMONIA (NH3)

ammonia-cal solutions of the tetroxide . A hydrated form of See also:

• COMPOSITION
• COMPOSITION (Lat. compositio, from componere, to put together)

composition OsC12.3H2O has been described . The tetrachloride, OsC14, is obtained as a dark red sublimate (mixed with the dichloride) when osmium is heated in dry chlorine . It is soluble in water, but the dilute solution readily decomposes on See also:

• STANDING

standing . It combines with the chlorides of the alkali metals to form characteristic See also:

• DOUBLE
• DOUBLE (from the Mid. Eng. duble, the form which gives the present pronunciation, through the Old Er. duble, from Lat. duplus, twice as much)

double salts of the type OsC14.2MCl (osmichlorides) . Potassium osmichloride, K2OsCl,, is formed when a mixture of osmium and potassium chloride is heated in a current of chlorine, or on adding potassium chloride and e lcohol to a solution of the tetroxide in hydrochloric acid . It crystallizes in dark red octahedra which are almost insoluble in cold water . The aqueous solution decomposes rapidly on boiling . Iodine has no action on osmium, but on warming the tetroxide with a mixture of potassium iodide and hydrochloric acid a deep See also:

• EMERALD

emerald green colour is produced, due to the formation of a See also:

• COMPOUND
• COMPOUND (from Lat. componere, to combine or put together)

compound OsI2.2HI; this reaction is a delicate test for osmium (E . Pinerua See also:

• ALVAREZ, DON JOSE (1768-1827)
• ALVAREZ, DON MANUEL (1727-1797)
• ALVAREZ, FRANCISCO (c. 1465-1541?)

Alvarez, Comptes rendus, 1905, 140, p .

1254) . Osmium disulphide, OsS2, is obtained as a dark See also:

• BROWN
• BROWN, CHARLES BROCKDEN (1771-181o)
• BROWN, FORD MADOX (1821-1893)
• BROWN, FRANCIS (1849- )
• BROWN, GEORGE (1818-188o)
• BROWN, HENRY KIRKE (1814-1886)
• BROWN, JACOB (1775–1828)
• BROWN, JOHN (1715–1766)
• BROWN, JOHN (1722-1787)
• BROWN, JOHN (1735–1788)
• BROWN, JOHN (1784–1858)
• BROWN, JOHN (1800-1859)
• BROWN, JOHN (1810—1882)
• BROWN, JOHN GEORGE (1831— )
• BROWN, ROBERT (1773-1858)
• BROWN, SAMUEL MORISON (1817—1856)
• BROWN, SIR GEORGE (1790-1865)
• BROWN, SIR JOHN (1816-1896)
• BROWN, SIR WILLIAM, BART
• BROWN, THOMAS (1663-1704)
• BROWN, THOMAS (1778-1820)
• BROWN, THOMAS EDWARD (1830-1897)
• BROWN, WILLIAM LAURENCE (1755–1830)

brown precipitate, insoluble in water, by passing sulphuretted See also:

• HYDROGEN [symbol H, atomic weight x-oo8 (0=16)]

hydrogen into a solution of an osmichloride . The tetrasulphide, OsS4, is similarly prepared when sulphuretted hydrogen is passed into acid solutions of the tetroxide . It is a brownish black solid, insoluble in solutions of the alkaline sulphides . The atomic See also:

• WEIGHT

weight of the metal has been determined by K . Seubert (Be,'., 1888, 21, p . 1839) from the See also:

• ANALYSIS (Gr. avci and Meta, to break up into parts)

analysis of potassium and ammonium osmichlorides, the values obtained being approximately 191 .