See also:

• COBALT (symbol Co, atomic weight 59)

COBALT (See also:

• SYMBOL (Gr. o-uµ(3oXov, a sign)

symbol Co, atomic See also:

• WEIGHT

weight 59)  , one of the metallic chemical elements . The See also:

• TERM

term " See also:

• COBALT (symbol Co, atomic weight 59)

cobalt " is met with in the writings of See also:

• PARACELSUS (c. 1490-1541)

Paracelsus, See also:

• AGRICOLA (originally SCHNEIDER, then SCHNITTER), JOHANNES (1494-1566)
• AGRICOLA (the Latinized form of the name BAUER), GEORG (1490-1555)
• AGRICOLA, CHRISTOPH LUDWIG (1667-1719)
• AGRICOLA, GNAEUS JULIUS (A.D. 37-93)
• AGRICOLA, JOHANN FRIEDRICH (1720-1774)
• AGRICOLA, MARTIN (c. 1500-1556)
• AGRICOLA, RODOLPHUS (properly ROELOF HUYSMANN) (1443-1485)

Agricola and See also:

• BASIL (Russ. VASILY)

Basil See also:

• VALENTINE, or VALENTINUS

Valentine, being used to denote substances which, although resembling metallic ores, gave no 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 on smelting . At a later date it was the name given to the See also:

• MINERAL

mineral used for the See also:

• PRODUCTION (Lat. productionem, from producere, to pro-duce)

production of a See also:

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

blue See also:

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

colour in See also:

• GLASS
• GLASS (O.E. glees, cf. Ger. Glas, perhaps derived from an old Teutonic root gla-, a variant of glo-, having the general sense of shining, cf. " glare," " glow ")
• GLASS, STAINED

glass . In 1735 G . Brandt prepared an impure cobalt metal, which was magnetic and very infusible . Cobalt is usually found associated with See also:

• NICKEL
• NICKEL (symbol Ni, atomic weight 58.68 (0=16))

nickel, and frequently with See also:

• ARSENIC (symbol As, atomic weight 75.0)

arsenic, the See also:

• CHIEF (from Fr. chef, head, Lat. caput)

chief ores being speiss-cobalt, (Co,Ni,Fe)As2, See also:

• COBALTITE

cobaltite (q.v.), See also:

• WAD

wad, cobalt See also:

• BLOOM (from A.S. bloma, a flower)

bloom, linnaeite, Co3S4, and skutterudite, CoAs3 . Its presence has also been detected in the See also:

• SUN
• SUN (0. Eng. sonne, Ger. sonne. Fr. soleil, Lat. sol, Gr. ijXior, from which comes helio- in various English compounds)

sun and in meteoric See also:

• IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron . For the technical preparation of cobalt, and its separation from nickel, see NICKEL . The metal is chiefly used, as the See also:

• OXIDE

oxide, for colouring glass and See also:

• PORCELAIN

porcelain . Metallic cobalt may be obtained by reduction of the oxide or chloride in a current of See also:

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

hydrogen at a red 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, or by See also:

• HEATING

heating the oxalate, under a layer of powdered glass . As prepared by the reduction of the oxide it is a 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:

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

powder . In the massive See also:

• STATE
• STATE, GREAT OFFICERS OF

state it has a colour resembling polished iron, and is malleable and very tough .

It has a specific gravity of 8.8,, and it melts at 1530° C . (H . Copaux) . Its mean specific heat between 9° and 97° C. is 0•10674 (H . See also:

• KOPP, HERMANN FRANZ MORITZ (1817-1892)

Kopp) . It is permanent in dry See also:

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

air, but in the finely divided state it rapidly combines with See also:

• OXYGEN (symbol 0, atomic weight 16)

oxygen, the compact metal requiring a strong heating to bring about this See also:

• COMBINATION (Lat. combinare, to combine)

combination . It decomposes See also:

• STEAM
• STEAM (0. Eng. steam, vapour, smoke, cf. Du. steam; the origin is unknown)

steam at a red heat, and slowly dissolves in dilute hydrochloric and sulphuric acids, but more readily in nitric See also:

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

acid . Cobalt See also:

• BURNS, JOHN (1858– )
• BURNS, ROBERT (1759-1796)
• BURNS, SIR GEORGE

burns in nitric oxide at 150 C. giving the monoxide . It may be obtained in the pure state, according to C . Winkler (Zeit. See also:

• FAIR

fair anorg . Chem., 1895, 8, p . 1), by electrolysing the pure sulphate in the presence of ammonium sulphate and See also:

• AMMONIA (NH3)

ammonia, using See also:

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

platinum electrodes, any occluded oxygen in the deposited metal being removed by heating in a current of hydrogen .

Three characteristic oxides of cobalt are known, the monoxide, CoO, the sesquioxide, Co203, and tricobalt tetroxide, Co304; besides these there are probably oxides of See also:

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

composition CoO2, Co3Q6, Co60s and Co4Oi . Cobalt monoxide, CoO, is prepared by heating the hydroxide or carbonate in a current of air, or by heating the oxide Co304 in a current of See also:

• CARBON (symbol C, atomic weight 12)

carbon dioxides It is a 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 coloured powder which is See also:

• STABLE

stable in air, but gives a higher oxide when heated . On heating in hydrogen, ammonia or carbon monoxide, or with carbon or See also:

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

sodium, it is reduced to the metallic state . It is readily soluble in warm dilute mineral acids forming cobaltous salts . Cobaltous hydroxide, Co(OH)2, is formed when a cobaltous 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 precipitated by See also:

• CAUSTIC (Gr. rcavvraubs, burning)

caustic potash in the See also:

• ABSENCE (Lat. absentia)

absence of air . A blue basic salt is precipitated first, which, on boiling, rapidly changes to the See also:

• ROSE
• ROSE (Rosa)
• ROSE, GEORGE (1744-1818)
• ROSE, HUGH JAMES (1795—1838)
• ROSE, WILLIAM STEWART (1775-1843)

rose-coloured hydroxide . It dissolves in acids forming cobaltous salts, and on exposure to air it rapidly absorbs oxygen, turning brown in colour . A. de Schulten (See also:

• CORN (a common Teutonic word; cf. Lat. granum, seed, grain)
• CORN (fromm Lat. corms, horn)

Corn ptes Rendus, 1889, x09, p . 266) has obtained it in a crystalline See also:

• FORM (Lat. forma)

form; the crystals have a specific gravity of 3.597, and are easily soluble in warm ammonium chloride See also:

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

solution . Cobalt sesquioxide, Co2O3, remains as a dark-brown powder when cobalt nitrate is gently heated . Heated at 190-30o° in a current of hydrogen it gives the oxide Co3O4, while at higher temperatures the monoxide is formed, and ultimately cobalt is obtained . Cobaltic hydroxide, Co(OH)3, is formed when a cobalt salt is precipitated by an alkaline hypochlorite, or on passing See also:

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

chlorine through See also:

• WATER

water containing suspended cobaltous hydroxide or carbonate .

It is a brown-See also:

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

black powder soluble in hydrochloric acid, chlorine being simultaneously liberated . This hydroxide is soluble in well cooled acids, forming solutions which contain cobaltic salts, one of the most stable of which is the acetate . Cobalt dioxide, CoO2, has not yet been isolated in the pure state; it is probably formed when See also:

• IODINE (symbol I, atomic weight '26.92)

iodine and caustic soda are added to a solution of a cobaltous salt . By suspending cobaltous hydroxide in water and adding hydrogen peroxide, a strongly acid liquid is obtained (after filtering) which probably contains cobaltous acid, H2CoO3 . The See also:

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

barium and See also:

• MAGNESIUM [symbol Mg, atomic weight 24.32 (0 = 16)]

magnesium salts of this acid are formed when baryta and See also:

• MAGNESIA

magnesia are fused with cobalt sesquioxide . Tricobalt tetroxide, Co3O4, is produced when the other oxides, or the nitrate, are heated in air . By heating a mixture of cobalt oxalate and sal-ammoniac in air, it is obtained in the form of See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute hard octahedra, which are not magnetic, and are only soluble in concentrated sulphuric acid . The cobaltous salts are formed when the metal, cobaltous oxide, hydroxide or carbonate, are dissolved in 'acids, or, in the See also:

• CASE
• CASE, JOHN (d. 1600)

case of the insoluble salts, by precipitation . The insoluble salts are rose-red or See also:

• VIOLET

violet in colour . The soluble salts are, when in the hydrated See also:

• CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition, also red, but in the anhydrous condition are blue . They are precipitated from their alkaline solutions as cobalt sulphide by sulphuretted hydrogen, but this precipitation is prevented by the presence of citric and tartaric acids; similarly the presence of ammonium salts hinders their precipitation by caustic alkalis . Alkaline See also:

• CARBONATES

carbonates give precipitates of basic carbonates, the formation of which is also retarded by the presence of ammonium salts .

For the See also:

• ACTION

action of ammonia on the cobaltous salts in the presence of air see Cobaltammines (below) . On the addition of See also:

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

potassium See also:

• CYANIDE

cyanide they give a brown precipitate of cobalt cyanide, Co(CN)2, which dissolves in excess of potassium cyanide to a 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 solution . Cobalt chloride, CoC12, in the anhydrous state, is formed by burning the metal in chlorine or by heating the sulphide in a current of the same See also:

• GAS

gas . It is blue in colour and sublimes readily . It dissolves easily in water, forming the hydrated chloride, CoC12.6H2O, which may also be prepared by dissolving the hydroxide or carbonate in hydrochloric acid . The hydrated salt forms rose-red prisms, readily soluble in water to a red solution, and in See also:

• ALCOHOL

alcohol to a blue solution . Other hydrated forms of the chloride, of composition CoC12.2H2O and CoC.I2.4H2O have been described (P . See also:

• SABATIER, LOUIS AUGUSTE (1839-1901)

Sabatier, See also:

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

Bull . See also:

• SOC

Soc . Chim . 51, p . 88; Bersch, Jahresb. d .

Chemie, 1867, p . 291) . 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 chlorides of composition CoCl,.NH4C1.6H2O; CoC12•SnCl4.6H2O and CoC12.2CdC12.12H2O are also known . By the addition of excess of ammonia to a cobalt chloride solution in absence of air, a greenish-blue precipitate is obtained which, on heating, dissolves in the solution, giving a rose-red liquid . This solution, on See also:

• STANDING

standing, deposits octahedra of the composition CoCl2.6NH3 . These crystals when heated to 120° C. lose ammonia and are converted into the See also:

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

compound CoC12.2NH3 (E . See also:

• FREMY, EDMOND (1814–1894)

Fremy) . The bromide, CoBr2, resembles the chloride, and may be prepared by similar methods . The hydrated salt readily loses water on heating, forming at See also:

• LOO (formerly called " Lanterloo," Fr. lanturlu, the refrain of a popular 17th-century song)

loo° C. the See also:

• HYDRATE

hydrate CoBr2.2H2O, and at 13o° C. passing into the anhydrous form . The iodide, See also:

• COLL

Coll, is produced by heating cobalt and iodine together, and forms a greyish-green See also:

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

mass which dissolves readily in water forming a red solution . On evaporating this solution the hydrated salt CoI2.6H2O is obtained in hexagonal prisms . It behaves in an analogous manner to CoBr2.6H2O on heating .

Cobalt fluoride, CoF2.2H2O, is formed when cobalt carbonate is evaporated with an excess of aqueous hydrofluoric acid, separating in rose-red crystalline crusts . See also:

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

Electrolysis of a solution in hydrofluoric acid gives cobaltic fluoride, CoF3 . Sulphides of cobalt of composition Co4S3, See also:

• COS
• COS, or STANKO (Ital. Stanchio, Turk. Islan-keui, by corruption from Etc rav KW)

CoS, Co3S4, Co2S3 and CoS2 are known . The most See also:

• COMMON

common of these sulphides is cobaltous sulphide, CoS, which occurs naturally as syepoorite, and can be artificially prepared by heating cobaltous oxide with See also:

• SULPHUR

sulphur, or by fusing anhydrous cobalt sulphate with barium sulphide and common salt . By either of these methods, it is obtained in the form of See also:

• BRONZE

bronze-coloured crystals . It may be prepared in the amorphous form by heating cobalt with sulphur dioxide, in a sealed See also:

• TUBE (Lat. tuba)

tube, at Zoo° C . In the hydrated condition js formed by the action of alkaline sulphides on cobaltous salts, or by precipitating cobalt acetate with sulphuretted hydrogen (in the absence of See also:

• FREE

free acetic acid) . It is a black amorphous powder soluble in concentrated sulphuric and hydrochloric acids, and when in the moist state readily oxidizes on exposure . Cobaltous sulphate, CoSO4.7H2O, is found naturally as the mineral bieberite, and is formed when cobalt, cobaltous oxide or carbonate are dissolved in dilute sulphuric acid . It forms dark red crystals isomorphous with ferrous sulphate, and readily soluble in water . By dissolving it in concentrated sulphuric acid and warming the solution, the anhydrous salt is obtained . Hydrated sulphates of composition CoSO4.6H2O, CoSO4.4H2O and CoSO4•See also:

• H2O (combined)

H2O are also known .

The heptahydrated salt combines with the alkaline sulphates to form double sulphates of composition CoSO4•M2SO4.6H20 (M=K, NH4, &c.) . The cobaltic salts corresponding to the oxide Co203 are generally unstable compounds which exist only in solution . H . See also:

• MARSHALL
• MARSHALL, ALFRED (1842– )
• MARSHALL, JOHN (1755–1835)
• MARSHALL, JOHN (1818-1891)
• MARSHALL, STEPHEN (c. 1594-1655)

Marshall (Proc . See also:

• ROY, WILLIAM (1726-1790)

Roy . Soc . Edin . 59, p . 760) has prepared cobaltic sulphate See also:

• CO2

Co2(SO4)3.18H2O, in the form of small needles, by the electrolysis of cobalt sulphate . In a similar way potassium and ammonium cobalt alums have been obtained . A cobaltisulphurous acid, probably H6 [(SO3)6•Co2] has been obtained by E . Berglund (Berichte, 1874, 7, p .

469), in aqueous solution, by dissolving ammonium cobalto- cobaltisulphite (NH4)2Co2 [(SO3)6.Co2] •14H2O in dilute hydrochloric or nitric acids, or by decomposition of its See also:

• SILVER

silver salt with hydro- chloric acid . The ammonium cobalto-cobaltisulphite is prepared by saturating an air-oxidized ammoniacal solution of cobaltous chloride with sulphur dioxide .