atomic See also:

• WEIGHT

weight 145.0 See also:

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

PLATINUM [See also:

• SYMBOL (Gr. o-uµ(3oXov, a sign)

symbol Pt (0=16)]  , a metallic chemical See also:

• ELEMENT (Lat. elementum)

element . The name, derived from platina, the diminutive of Span. plena (See also:

• SILVER

silver), was first given to a See also:

• MINERAL

mineral, See also:

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

platinum ore or native platinum, originally discovered in See also:

• SOUTH
• SOUTH, ROBERT (1634–1716)

South See also:

• AMERICA

America, from the resemblance to silver . See also:

• RUSSIA
• RUSSIA (Rossiya)

Russia furnishes about 95% of the See also:

• WORLD

world's See also:

• ANNUAL

annual See also:

• SUPPLY (through Fr. from Lat. supplere, to fill up)

supply of platinum . Native platinum occurs usually in small metallic scales or See also:

• FLAT (a modification of O. Eng. flet, an obsolete word of Teutonic origin, meaning the ground beneath the feet)

flat grains, sometimes in the See also:

• FORM (Lat. forma)

form of irregular nuggets, and occasionally, though rarely, in small crystals belonging to the cubic See also:

• SYSTEM

system . Grains of platinum have been found embedded, with See also:

• CHROMITE

chromite, in See also:

• SERPENTINE

serpentine derived from an See also:

• OLIVINE

olivine-See also:

• ROCK
• ROCK (O.Fr. rake, Sp. rota, Ital. rocca; possibly from a Lat. form rupica, from rupes, rock)
• ROCK, DANIEL (1799–187t)

rock, 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 having probably separated out from an See also:

• ORIGINAL

original basic magma . It is said to occur also in See also:

• VEINS

veins in syenitic and other rocks . Usually, however, platinum is found in detrital deposits, especially in auriferous sands, where it is associated with osmiridium (known also as iridosmine), chromite, See also:

• MAGNETITE

magnetite, See also:

• CORUNDUM

corundum, See also:

• ZIRCON

zircon, &c . The platinum has a See also:

• STEEL, FLORA ANNIE (1847– )

steel 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 or silver-See also:

• WHITE
• WHITE, ANDREW DICKSON (1832– )
• WHITE, GILBERT (1720–1793)
• WHITE, HENRY KIRKE (1785-1806)
• WHITE, HUGH LAWSON (1773-1840)
• WHITE, JOSEPH BLANCO (1775-1841)
• WHITE, RICHARD GRANT (1822-1885)
• WHITE, ROBERT (1645-1704)
• WHITE, SIR GEORGE STUART (1835– )
• WHITE, SIR THOMAS (1492-1567)
• WHITE, SIR WILLIAM ARTHUR (1824--1891)
• WHITE, SIR WILLIAM HENRY (1845– )
• WHITE, THOMAS (1628-1698)
• WHITE, THOMAS (c. 1550-1624)

white See also:

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

colour and a metallic lustre; is often magnetic, sometimes with See also:

• POLARITY (Lat. polaris, poles, pole)

polarity; has a hardness of about 4.5 and a specific gravity varying with its See also:

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

composition from 14 to 19 . Native platinum usually contains more or less See also:

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

iron and See also:

• COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper, often See also:

• GOLD
• GOLD [symbol Au, atomic weight 195.7(H = 1),197.2(0 =16)]

gold, and invariably a small proportion of some of the allied metals—See also:

• IRIDIUM (symbol Ir.; atomic weight 193.1)

iridium, See also:

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

osmium, See also:

• RUTHENIUM [symbol Ru, atomic weight 101.7 (0=16)]

ruthenium, See also:

• RHODIUM [symbol Rh; atomic weight 102.9 (0=16)]

rhodium and See also:

• PALLADIUM (Gr. sraXXit&ov)
• PALLADIUM [symbol Pd, atomic weight Io6.7 (O=16)]

palladium . From the associated metals it was named by J . F . L .

See also:

• HAUSMANN, JOHANN FRIEDRICH LUDWIG (1782-1859)

Hausmann polyxene (Gr. iroXbs, many, and Evoc, a See also:

• GUEST (a word common to Teutonic languages; cf. Ger. Gast, and Swed. gust; cognate with Lat. hostis, originally a stranger, hence enemy; cf. " host " )
• GUEST, EDWIN (1800–188o)

guest), whilst from its occurrence as a white metal in auriferous alluvia it is sometimes known to miners as " white gold." Platina del See also:

• PINTO
• PINTO, ANIBAL (1825–1884)
• PINTO, FERNAO MENDES (1509–1583)

Pinto was the name by which native platinum was first introduced into See also:

• EUROPE

Europe from South America about the See also:

• MIDDLE

middle of the 18th See also:

• CENTURY (from Lat. centuria, a division of a hundred men)

century . Although it appears to have been known locally much earlier, the See also:

• ATTENTION (from Lat. ad-tendo, await, expect; the condition of being " stretched " or " tense ")

attention of scientific men in Europe was first directed to it by See also:

• ANTONIO
• ANTONIO (1429—1498)
• ANTONIO, NICOLAS (1617-1684)

Antonio de Ulloa y See also:

• GARCIA
• GARCIA (DEL POPOLO VICENTO), MANOEL (1775-1832)

Garcia de La Torre, a Spaniard who joined a See also:

• FRENCH
• FRENCH, DANIEL CHESTER (1850– )
• FRENCH, NICHOLAS (1604-1678)

French scientific expedition to See also:

• PERU
• PERU (apparently from Biru, a small river on the west coast of Colombia, where Pizarro landed)

Peru in 1735, and published in 1748 an See also:

• ACCOUNT
• ACCOUNT (through O. Fr. acont, Late Lat. comptum, cornputare, to calculate)

account of his See also:

• JOURNEY (through O. Fr. jornee or journee, mod. Fr. journee, from med. Lat. diurnata, Lat. diurnus, of or belonging to dies, day)

journey, in which he refers to platinum, though not under that name, as occurring with gold in New See also:

• GRANADA
• GRANADA, LUIS DE (1504-1588)

Granada (now See also:

• COLOMBIA

Colombia) . See also:

• SIR

Sir See also:

• WILLIAM
• WILLIAM (1143-1214)
• WILLIAM (1227-1256)
• WILLIAM (1J33-1584)
• WILLIAM (A.S. Wilhelm, O. Norse Vilhidlmr; O. H. Ger. Willahelm, Willahalm, M. H. Ger. Willehelm, Willehalm, Mod.Ger. Wilhelm; Du. Willem; O. Fr. Villalme, Mod. Fr. Guillaume; from " will," Goth. vilja, and " helm," Goth. hilms, Old Norse hidlmr, meaning
• WILLIAM (c. 1130-C. 1190)
• WILLIAM, 13TH

William See also:

• WATSON, RICHARD (1737-1816)
• WATSON, THOMAS (c. 1557–1592)
• WATSON, WILLIAM (1858- )
• WATSON, WILLIAM (c. 1559-1603)

Watson, an See also:

• ENGLISH

English physicist, had, however, in 1741 received some grains of the mineral, probably from the ' Reproduced by J . F . Riano, in Studies of See also:

• EARLY
• EARLY, JUBAL ANDERSON (1816-1894)

Early See also:

• SPANISH

Spanish See also:

• MUSIC

Music (See also:

• LONDON

London, 1887) . ' See facsimile edited by Dr See also:

• GEORGE
• GEORGE, 8TH MARQUESS OF TWEEDDALE (1787-1876)
• GEORGE, HENRY (1839—1897)
• GEORGE, LAKE
• GEORGE, SAINT (d. 303)

George See also:

• WARNER, OLIN LEVI (1844-1896)
• WARNER, SETH (1743-1784)
• WARNER, WILLIAM (1558?-16o9)

Warner, pl. See also:

• XXVIII

xxviii. fol . 51 . 3 See F . J . See also:

• FURNIVALL, FREDERICK JAMES (1825-1910)

Furnivall, See also:

• CAPTAIN (derived from Lat. ca put, head, through the Low Lat. capitanus)

Captain See also:

• COX, DAVID (1783-1859)
• COX, JACOB DOLSON (1828-1900)
• COX, KENYON (1856– )
• COX, RICHARD (I3oo ?–1581)
• COX, SAMUEL (1826–1893)
• COX, SAMUEL HANSON (1793-1880)
• COX, SIR GEORGE WILLIAM (1827-1902)

Cox, his See also:

• BALLADS

ballads and Books, or See also:

• ROBERT
• ROBERT (1275—1343)
• ROBERT, HUBERT (1753-1808)
• ROBERT, LOUIS LEOPOLD (1794-1835)

Robert Laneham's See also:

• LETTER (through Fr. lettre from Lat. littera or litera, letter of the alphabet; the origin of the Latin word is obscure; it has probably no connexion with the root of linere, to smear, i.e. with wax, for an inscription with a stilus)

Letter A.D . 1575 (London, 1871), clx . 86 .

re-melted in a reverberatory See also:

• FURNACE

furnace with See also:

• GALENA

galena or litharge, the See also:

• LEAD
• LEAD (pronounced iced)

lead platinum alloy being then cupelod, and the platinum fused into an See also:

• INGOT

ingot by re-smelting in a See also:

• LIME
• LIME (O. Eng. lim, Lat. limes, mud, from linere, to smear)

lime furnace (see Dingler's Polytech . Journ . 1859, 153, p . 38; 1859, 154, p . 383, 1862, 165, p . 205) . The platinum so obtained is not pure . In See also:

• WOLLASTON, WILLIAM (1659--1724)
• WOLLASTON, WILLIAM HYDE (1766-1828)

Wollaston's wet method the ore is dissolved in aqua regia, the osmiridium, ruthenium and rhodium being See also:

• LEFT

left unattacked, and the platinum precipitated as ammonium platinochloride by adding ammonium chloride in the presence of an excess of See also:

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

acid . The 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 chloride is then washed, dried and ignited, leaving a See also:

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

residue of metal . G . Matthey (Chem . See also:

• NEWS

News, 1879, 39, p .

175) obtains pure platinum from the commercial metal by fusing the latter with a large excess of lead . The lead alloy is then treated with a dilute nitric acid and the insoluble portion taken up in dilute aqua regia, From the See also:

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

solution so obtained lead is precipitated as sulphate, and platinum and rhodium as double ammonium chlorides . The rhodium ammonium chloride is converted by fusing with See also:

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

potassium and ammonium bisulphates into rhodium sulphate, which is then removed by extraction with See also:

• WATER

water, when a residue of finely divided platinum remains . The See also:

• GERMAN
• GERMAN, DUTCH AND SCANDINAVIAN

German See also:

• FIRM

firm of Heraus (in See also:

• HANOVER
• HANOVER (Ger. Hannover)

Hanover) 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 the raw ore with aqua regia and water under pressure, evaporate the solution to dryness, and heat the residue to 125° C . A clear aqueous See also:

• EXTRACT (from Lat. extrahere, to draw out)

extract of the residue is then acidified with hydrochloric acid and precipitated with ammonium chloride . The double chloride is ignited and the finely divided platinum so obtained is fused in the oxyhydrogen See also:

• BLOWPIPE

blowpipe . same locality, though brought by way of See also:

• JAMAICA

Jamaica; and it was he who first described it in 1750 as a new metal . Native platinum was discovered in 1819 in the gold washings of Verkhniy-Isetsk, in the Urals, but it was not until 1822 that its true nature was recognized . The See also:

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

chief See also:

• RUSSIAN

Russian localities are in the districts of Nizhne Tagilsk and Goroblagodatsk, where it is found in shallow See also:

• DRIFT (from "drive ")

drift deposits, containing pebbles of serpentine, which represent the original See also:

• MATRIX

matrix . The Iset See also:

• DISTRICT

district has acquired importance in See also:

• RECENT

recent years . Although the platinum-bearing gravels usually contain a very small proportion of the metal, the See also:

• AVERAGE

average in 1895 being only 11 dwt. to the ton, See also:

• RICH, BARNABE (c. 1540-1617)
• RICH, CLAUDIUS JAMES (1787-1821)
• RICH, JOHN (1692-1761)
• RICH, PENELOPE, LADY (c. 1562–1607)
• RICH, RICHARD, 1ST BARON RICH (1490?-1567)

rich discoveries have occasionally been made in the See also:

• HISTORY

history of the workings, and nuggets of exceptional See also:

• SIZE

size have been unearthed . The largest recorded specimens are one of 310 OZ. from Nizhne Tagilsk, and another of 722 oz. from the Goroblagodatsk district .

In 1831 platinum ore was recognized in the gold-bearing deposits of See also:

• BORNEO

Borneo, where it had previously been regarded as worthless, being known to the natives as mas kodok (See also:

• FROG

frog gold) . Although recorded from various parts of the See also:

• ISLAND (O.E. ieg =isle, +land')

island, its occurrence seems to be definitely known only in Tanah-See also:

• LAUT

Laut, in the south-See also:

• EAST
• EAST, ALFRED (1849- )

east of Borneo . In See also:

• AUSTRALIA

Australia platinum ore has been found near Fifield (near Condobelin), New South See also:

• WALES (Cymru, Gwalia, Cambria)

Wales; whilst in New See also:

• ZEALAND (also SEALAND Or SEELAND; Danish Sjaelland)

Zealand it occurs in sands and gravels in the See also:

• THAMES

Thames gold-See also:

• FIELD (a word common to many West German languages, cf. Ger. Feld, Dutch veld, possibly cognate with O.E. f olde, the earth, and ultimately with root of the Gr. irAaror, broad)
• FIELD, CYRUS WEST (1819-1892)
• FIELD, DAVID DUDLEY (18o5-1894)
• FIELD, EUGENE (1850-1895)
• FIELD, FREDERICK (18o1—1885)
• FIELD, HENRY MARTYN (1822-1907)
• FIELD, JOHN (1782—1837)
• FIELD, MARSHALL (183 1906)
• FIELD, NATHAN (1587—1633)
• FIELD, STEPHEN JOHNSON (1816-1899)
• FIELD, WILLIAM VENTRIS FIELD, BARON (1813-1907)

field, the Takaka See also:

• RIVER

River and the See also:

• GORGE

Gorge River flowing into Awarua See also:

• BAY

Bay . Many localities in See also:

• NORTH
• NORTH, BARONS
• NORTH, MARIANNE (1830—1890)
• NORTH, ROGER (1653-1734)
• NORTH, SIR THOMAS (1535?-16o1?)

North America have yielded platinum, generally in See also:

• BEACH

beach sands or in auriferous alluvia, and in some cases the deposits are of commercial importance . The metal is found in See also:

• ALASKA

Alaska, See also:

• BRITISH

British See also:

• COLUMBIA

Columbia, See also:

• OREGON

Oregon (See also:

• DOUGLAS
• DOUGLAS, GAVIN (1474?-1522)
• DOUGLAS, JOHN (1721—1807.)
• DOUGLAS, SIR CHARLES
• DOUGLAS, SIR HOWARD
• DOUGLAS, STEPHEN ARNOLD (18,3–1861)

Douglas See also:

• COUNTY (through Norm. Fr. comae, cf. O. Fr. cunte, conk', Mod. Fr. comae, from Lat. comitatus, cf. Ital. comitato, Prov. comtat; see COUNT)

county) and See also:

• CALIFORNIA
• CALIFORNIA, LOWER (Baja California)
• CALIFORNIA, UNIVERSITY OF

California (See also:

• BUTTE
• BUTTE (O. Fr. butte, a hillock or rising ground)

Butte county, Trinity county, Del Norte ccunty) . It has been recorded also from the states of New See also:

• YORK
• YORK (HOUSE OF)
• YORK, EDMUND OF LANGLEY, DUKE OF (1341-1402)
• YORK, EDWARD
• YORK, FREDERICK AUGUSTUS, DUKE OF (1763-1827)
• YORK, RICHARD, DUKE

York and North Carolina . In a nickeliferous sulphide ore worked at See also:

• SUDBURY
• SUDBURY, SIMON OF (d. 1381)

Sudbury, in See also:

• ONTARIO
• ONTARIO, LAKE

Ontario, platinum has been discovered in the form of an arsenide (Pt As2), which has been called sperrylite by H . L . See also:

• WELLS
• WELLS, CHARLES JEREMIAH (1798?–1879)
• WELLS, DAVID AMES (1828—1898)
• WELLS, HERBERT GEORGE (1866— )
• WELLS, SIR THOMAS SPENCER, 1ST BART

Wells, who analysed it in 1889, and named it after F . L . Sperry, of Sudbury . It belongs to the See also:

• PYRITES

pyrites See also:

• GROUP

group, and is interesting as being the only known mineral in which platinum occurs in See also:

• COMBINATION (Lat. combinare, to combine)

combination except as alloy .

Native platinum seems to be a mineral of rather wide See also:

• DISTRIBUTION (Lat. distribuere, to deal out)

distribution, but in very sparse quantity . The sands of the See also:

• RHINE (Lat. Rhenus, Ger. Rhein, Fr. Rhin, Dutch Rhyn, or Rijn)

Rhine, derived from Alpine rocks, have been found to contain platinum in the proportion of 0.0004% . It has also been found in the sands of the Ivalo River in 'See also:

• LAPLAND, or LAPPLAND

Lapland; it is recorded from Roros in See also:

• NORWAY
• NORWAY (Norge)

Norway; and it was detected by W . See also:

• MALLET (or MALLOCH), DAVID (?17o5–1765)
• MALLET, PAUL HENRI (173o–18o7)

Mallet in some of the gold-sands of the streams in Co . See also:

• WICKLOW

Wicklow, See also:

• IRELAND
• IRELAND, CHURCH
• IRELAND, CHURCH OF
• IRELAND, JOHN (1761-1842)
• IRELAND, JOHN (1838- )
• IRELAND, WILLIAM HENRY (1777-1835)

Ireland . The table shows the See also:

• OFFICIAL (Late Lat. QJicialis, for class. Lat. apparitor, from officium, office, duty)

official amount (in ounces See also:

• TROY
• TROY, JEAN FRANCOIS DE (1679–1752)

Troy) of platinum produced in Russia for certain years, the actual amounts are much larger: See also:

• YEAR

Year . Amount . Year . Amount . 1890 116,640 1904 161,950 1895 141,757 1905 167,950 'goo 163,060 1906 185,492 1901 203,257 1907 172,758 1902 197,024 1908 157,005 1903 192,976 (See also:

• ROTHWELL

Rothwell's Mineral See also:

• INDUSTRY (Lat. industria, from indu-, a form of the pre, position in, and either stare, to stand, or struere, to pile up)

Industry, 1908.) Platinum is largely used for the manufacture of chemical apparatus, incandescent lamps, thermo-couples; in the manufacture of sulphuric acid by the contact See also:

• PROCESS

process, in See also:

• PHOTOGRAPHY (Gr. bias, light, and ypa w, to write)
• PHOTOGRAPHY, CELESTIAL

photography, and in See also:

• JEWELRY (O. Fr. jouel, Fr. joyau, perhaps from joie, joy; Lat. gaudium; retranslated into Low Lat. jocale, a toy, from jocus, by misapprehension of the origin of the word)

jewelry . The See also:

• PRICE
• PRICE, BARTHOLOMEW (1818–1898)
• PRICE, BONAMY (1807-1888)
• PRICE, RICHARD (1723-1791)

price of See also:

• TILE (0. Eng. tigel, Fr. tuile, connected with Lat. tegula)

tile metal has risen considerably, not so much on account of the restricted supply, but chiefly because the See also:

• SOURCES

sources of supply have passed into the hands of a few individuals . The following data show the fluctuations in he average price of platinum ingot per once Troy: s. d .

£ s. d . 1874-1898: 1 5 2 to 2 2 0 1899-1905: 3 13 6 „ 4 10 4 1906: 4 15 2 „ 7 19 8 1907: 7 0 0„ 6 18 8 908: 5 2 6 (average) price . Platinum may be extracted from its ore by both wet and dry processes . In the latter method, due to H . Sainte-Claire-Deville and H . J . Debray, the ore is smelted in a furnace constructed of two blocks of lime, and the metallic See also:

• BUTTON (Fr. bouton, O. Fr. boton, apparently from the same root as bouter, to push)

button so obtained is Platinum is a greyish-white metal which is exceedingly malleable and ductile; the addition of a small quantity of iridium hardens it and diminishes its ductility very considerably . Its specific gravity is 20.85 to 21.71, and its mean specific heat from o to See also:

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

loo° C. is 0.0323 (J . Violle, Comptes rendus, 1877, 85, p . 543); W . P . White (Amer .

Journ . Sci., 1909, iv . 28, p . 334) gives the See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

general See also:

• FORMULA
• FORMULA (Lat. diminutive of forma, shape, pattern, &c., especially used of rules of judicial procedure)

formula St=o•o3198+3.4Xio st . St being the specific heat at t°C . Its temperature of See also:

• FUSION

fusion is in the neighbourhood of 1700 to 1800°C., various intermediate values having been obtained by different investigators (see J . A . Harker, Chem . News, 1905, 91, p . 262; C . Fery and C . Chenevean, Comptes rendus, 1909, 148, p .

401; also C . W . Waidner and G . H . See also:

• BURGESS (Med. Lat. burgensis, from burgus, a borough, a town)
• BURGESS, DANIEL (1645-1713)
• BURGESS, THOMAS (1756–1837)

Burgess, ibid., 1909, 148, p . 1177) . Its latent heat of fusion is 27.18 calories (Violle, loc. cit) . The metal has been obtained in the crystalline See also:

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

condition by See also:

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

distillation in the electric furnace, or by decomposing its fluoride at a red heat (H . See also:

• MOISSAN, HENRI (1852-1907)

Moissan) . Platinum, like palladium, absorbs large quantities of See also:

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

hydrogen and other gases, the occluded See also:

• GAS

gas then becoming more "active"; for this See also:

• REASON (Lat. ratio, through French raison)

reason platinum is used largely as a catalytic See also:

• AGENT (from Lat. agere, to act)

agent . Several forms of platinum, other than the massive form, may be obtained . Spongy platinum is produced when ammonium platinochloride is ignited; platinum See also:

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

black on the reduction of acid solutions of platinum salts; and colloidal platinum by passing an electric arc between two platinum wires under the See also:

• SURFACE

surface of pure water (G .

Bredig, Zeit. phys . Chem., 1901, 37, pp . 1, 323) . Platinum is practically unoxidizable; it combines directly with See also:

• PHOSPHORUS (Gr. 4ws, light, sPEpety, to bear)

phosphorus, See also:

• ARSENIC (symbol As, atomic weight 75.0)

arsenic, See also:

• ANTIMONY (symbol Sb, atomic weight 120.2)

antimony, See also:

• SILICON [symbol Si, atomic weight 28.3 (0= 16)]

silicon, See also:

• BORON (symbol B, atomic weight I I)

boron, and See also:

• FLUORINE (symbol F, atomic weight 19)

fluorine, and with almost all other metals . It is practically unattacked by all acids, dissolving only in aqua regia or in mixtures which generate See also:

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

chlorine . When fused with alkaline hydroxides in the presence of See also:

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

air it forms platinates . It is readily attacked by fused nitrates, and by potassium See also:

• CYANIDE

cyanide and ferrocyanide . All the platinum compounds when heated strongly decompose, and leave a residue of the metal . Of platinum salts, in the true sense of the word, none exist; there is no carbonate, nitrate, sulphate, &c; halide salts, however, are known, but are obtained in an indirect manner . Platinum monoxide, PtO, obtained by See also:

• HEATING

heating the corresponding See also:

• HYDRATE

hydrate, is a dark-coloured See also:

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

powder which is easily reduced to the metal (L . See also:

• WOHLER, FRIEDRICH (1800-1882)

Wohler, See also:

• BEE (Sanskrit blza, AS. ben, Lat. apis)

Bee., 1903, 36, p . 3475) .

The hydrated form, PtO.2H2O, is obtained impure by precipitating the dichloride with See also:

• CAUSTIC (Gr. rcavvraubs, burning)

caustic soda, or by adding caustic soda to a boiling solution of potassium platinous chloride, K2PtCI4, the precipitate being rapidly washed and dried in vacuo (L . Wohler, Zeit. anorg . Chem., 1904, 40, p . 423) . It is a black powder; when freshly prepared it is soluble in concentrated acids, but when dried it is insoluble . It is an acidic See also:

• OXIDE

oxide, the dioxide being both acidic and basic . It behaves as a strong oxidizing and reducing agent . C . Engler and L . Wohler (Zeit. anorg . Chem., 1901, 29, p . 1) have shown that platinum black, containing occluded See also:

• OXYGEN (symbol 0, atomic weight 16)

oxygen, is soluble in dilute hydrochloric acid and also liberates See also:

• IODINE (symbol I, atomic weight '26.92)

iodine from potassium iodide, and that the ratio between the amount of platinum dissolved and the amount of oxygen occluded agrees with the formation of a comppound corresponding to the formula PtO, _ Platinum dioxide (platinic oxide), PtOr4H2O, is obtained by adding an excess of caustic soda solution to a boiling solution of chlorplatinic acid, the hot solution being diluted and neutralized with acetic acid .

It loses its water of hydration when heated, finally decomposing into platinum and oxygen . When freshly prepared it is soluble in dilute acids . Other hydrated forms of composition, PtO2.3H2O and PtO2.2H2O, have been described (E . Prost, See also:

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

Bull. See also:

• SOC

soc. chim., 1886, 46, p . 156; H . Topsoe, Ber., 187o, 3, p . 462) . The tetrahydrate may be considered as an acid, H2Pt(OH)s, for salts are known (namely the platinates) corresponding to it, those of the See also:

• ALKALI

alkali metals being soluble in water, and possessing an alkaline reaction (M . See also:

• BLONDEL, DAVID (1591-1655)
• BLONDEL, JACQUES FRANCOIS (1705-1774)

Blondel, See also:

• ANN

Ann. chim. phys., 1905 [viii.], 6, p . 81) . A similar set of chlorine-holding compounds is also known, the chlorine replacing one or more hydroxyl See also:

• GROUPS
• GROUPS, THEORY

groups and giving rise to complexes of composition, H2[PtCls(OH)], H2[PtCI4(OH)2], Ht[PtC12(OH)4] and H2[PtCI(OH)s] . The platinic salts (derived from PtO2) are yellow or 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 solids, which are readily reduced to the metallic condition .

They give with sulphuretted hydrogen a dark brown precipitate, soluble in excess of ammonium sulphide . Potassium iodide gives a brown solution with See also:

• GRADUAL (Med. Lat. gradualis, of or belonging to steps or degrees; gradus, step)

gradual formation of a precipitate . They form characteristic precipitates with potassium and ammonium chlorides . The platinous salts are brown or colourless solids which, with sulphuretted hydrogen, give a dark brown precipitate of platinum sulphide, and with potassium iodide a gradual precipitation of platinic iodide, PtI2 . Platinum trioxide, PtO3, is obtained as See also:

• K20

K20.3PtO3, by electrolysing a solution of platinic hydroxide in potash, this See also:

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

compound with acetic acid giving the oxide as a brown, easily decomposable powder (L . Wohl: r and F . See also:

• MARTIN (Martinus)
• MARTIN, BON LOUIS HENRI (1810-1883)
• MARTIN, CLAUD (1735-1800)
• MARTIN, FRANCOIS XAVIER (1762-1846)
• MARTIN, HOMER DODGE (1836-1897)
• MARTIN, JOHN (1789-1854)
• MARTIN, LUTHER (1748-1826)
• MARTIN, SIR THEODORE (1816-1909)
• MARTIN, SIR WILLIAM FANSHAWE (1801–1895)
• MARTIN, ST (c. 316-400)
• MARTIN, WILLIAM (1767-1810)

Martin, Bee., 1909, 42, p . 3326) . • Platinum bichloride, PtC12, is obtained by heating chlorplatinic acid to 300-350° C . (J . J . See also:

• BERZELIUS, JONS JAKOB (1779-1848)

Berzelius), or, mixed with more or less platinic chloride, by passing chlorine over spongy platinum at a temperature of 250 C .

(P . See also:

• SCHUTZENBERGER, PAUL (1829–1897)

Schutzenberger, Comptes rendus, 187o, 70, pp . 1134, 1287) . It may also be obtained by the decomposition of the compound HC1•PtCl2.2H2O (see below) at loo' C., this method giving a very pure product (L . F . Nilson, Journ. prak . Chem., 1877 (2), 15, p . 26o) . It is a brown or greyish 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 solid, which is soluble in hydrochloric acid . It decomposes into its constituent elements when heated . It combines with many chlorides to form characteristic double salts . Platinum bichloride combines with See also:

• CARBON (symbol C, atomic weight 12)

carbon monoxide, yielding compounds of composition, PtC12.CO, PtCl2•zCO, 2PtC12.3CO (P .

Schutzenberger, Ann. chim. phys., 187o (4), 21, p . 350) . Hydrogen platinochloride or chlorplatmous acid, H2PtCl4, is only known in solution, and as such is obtained when platinum bichloride is dissolved in hydrochloric acid, or by decomposing the See also:

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

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 with sulphuric acid, or the silver salt with hydrochloric acid . Its salts, the platinochlorides or chlorplatinites, are obtained by reducing the chlorplatinates or directly from the acid itself . They are mostly soluble in water giving red solutions . They are readily oxidized, and nascent hydrogen reduces them to metallic platinum . Potassium platinochloride or chlorplatinite, K2PtCI4, is prepared by reducing hydrogen platinichloride with See also:

• SULPHUR

sulphur dioxide, or potassium platinichloride with potassium oxalate in the presence of iridium (Klason, Ber., 1904, 37, p . 1360); or by adding potassium chloride to a solution of platinum bichloride in hydrochloric acid . It crystallizes in dark red prisms, is readily soluble in water, but insoluble in See also:

• ALCOHOL

alcohol . The solution of the See also:

• FREE

free acid when concentrated in vacuo leaves a residue of HCI.PtCl2.2H20 . When the free acid is reduced by alcohol, or when See also:

• ETHYLENE, or ETHENE, C2H4

ethylene is passed into a solution of platinum bichloride in hydrochloric acid, PtCl2•C2H4 is obtained as a brown amorphous See also:

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

mass which decomposes when heated . When the bichloride is heated in a current of carbon monoxide, a sublimate of platinomonocarbonyl dichloride, PtC12CO, dicarbonyl dichloride,PtC12(CO)2, and tiicarbonyl tetrachloride, Pt2C14(CO)3, is obtained .

The first forms See also:

• BRIGHT, JOHN (1811-188g)
• BRIGHT, SIR CHARLES TILSTON

bright yellow needles and the second white acicular crystals . The bichloride also combines with phosgene to form PtC12.2LOCl2 . Platinic chloride, PtCl4, is obtained when chlorplatinic acid is heated in a current of dry hydrochloric acid gas to 165° C . (W . Pullinger, Journ . Chem . Soc., 1892, 61, p . 422) or in a current of dry chlorine at 275° C . (A . See also:

• ROSENHEIM

Rosenheim and W . Lowenstamm, Zeit. anorg . Chem., 1903, 37, p .

394) . It forms a reddish brown crystalline mass which is very hygroscopic . Numerous hydrates are known . The chloride is characterized by the readiness with which it forms double salts with the metallic chlorides and with the hydrochlorides of most organic bases . Chlorplatinic acid, H2PtCI6.6H20, is obtained by dissolving platinum in aqua regia containing an excess of hydrochloric acid, or by the See also:

• ACTION

action of chlorine (dissolved in hydrochloric acid) on platinum sponge . It crystallizes in needles, which are very deliquescent and dissolve easily in water . It melts in its own water of See also:

• CRYSTALLIZATION

crystallization at 7o° C., and when heated in vacuo to loo° C. it leaves a residue of composition HCI.PtC14.2H20 . The potassium and ammoniumn salts and the salts it forms with organic bases are characterized by their exceedingly small solubility in water . The aqueous solution of the acid reddens See also:

• LITMUS (apparently a corruption of lacmus, Dutch lacmoes, lac, lac, and moes, pulp, due to association with " lit," an obsolete word for dye, colour; the Ger. equivalent is Lac/emus, Fr tournesol)

litmus and decomposes the metallic See also:

• CARBONATES

carbonates . Its salts may he prepared by the See also:

• DIRECT

direct action of the acid on the metallic hydroxides or carbonates, and are usually of an See also:

• ORANGE
• ORANGE (Citrus Aurantium)
• ORANGE, HOUSE OF

orange or yellow colour and are mostly soluble in water . Potassium chlorplatinate, K2PtC16, is obtained, in the form of a yellow crystal-See also:

• LINE

line precipitate, when a concentrated solution of a potassium saltis added to a solution of chlorplatinic acid . It crystallizes in octahedra which are scarcely soluble in water, and practically insoluble in See also:

• ABSOLUTE (Lat. absolvere, to loose, set free)

absolute alcohol .

It decomposes at a red heat into platinum, chlorine and potassium chloride . The corresponding See also:

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

sodium salt, Na2PtC1s.6H20, is much more soluble in water and in alcohol . The ammonium salt, (NH4)2PtCls, resembles the potassium salt in its solubility in water and in alcohol . Corresponding See also:

• BROME, ALEXANDER (162o-1666)
• BROME, RICHARD (d. 1652)

brome- and iodo- compounds are known . Platinum bifloride and tetrafluoride, PtF2 and PtF4, were obtained simultaneously by H . Moissan (Ann. chim. phys., 1894 (6), 24, p . 282) by the action of fluorine on platinum at 500-600° C . They may be separated by taking See also:

• ADVANTAGE

advantage of their different solubilities in water . Platinum monosulphide, PtS, is obtained by the direct See also:

• UNION
• UNION (known locally as Union Hill and officially as Town of Union)

union of platinum and sulphur; by heating ammonium chlorplatinate with sul phur; or by the action or aulphuretted hydrogen on the chlorplatinites . It is a dark coloured powder which is almost insoluble in aqua regia . It decomposes when heated strongly leaving a residue of metallic platinum, the same reduction taking See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place at comparatively See also:

• LOW, SETH (1850- )
• LOW, WILL HICOK (1853- )

low temperatures when it is heated in a current of hydrogen . Platinic sulphide, PtS2, is formed when the chlorplatinates are heated with sulphuretted hydrogen to 6o° C .

The precipitate must be rapidly washed and dried in vacuo, since it oxidizes rapidly on exposure to air . It is a black powder, which when heated strongly in air decomposes and leaves a residue of platinum, but if heated in See also:

• ABSENCE (Lat. absentia)

absence of air leaves a residue of the monosulphide . It is scarcely affected by acids and is little soluble in solutions of the alkaline sulphides . Sulphides of composition Pt2S3 and PtsS6 have been described (R . See also:

• SCHNEIDER, JOHANN GOTTLOB (1750-1822)
• SCHNEIDER, LOUIS (1805-1878)

Schneider, Pogg . Ann., 1869, 138, p . 604; 1873, 148, p . 633; 1873, 149, p . 381) . A salt of composition, Pt(OH)4.H2SO4.See also:

• H2O (combined)

H2O, has been prepared by M . Blondel (Ann. chim. phys., 1905, (8), 6, p . 81) by the solution of the hydrate H2Pt(OH)s, i.e .

PtO2.4H20, in dilute sulphuric acid (I:I) at 0° C . On the addition of 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 concentrated sulphuric acid to the solution so obtained, the above salt is precipitated in the form of See also:

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

minute needles, which readily decompose in the presence of water . A platinum sulphate, Pt(SO4)2.2H20, has been obtained by L . Stuchlik (Ber., 1904, 37, p . 2913) by the action of sulphuric acid (s.g . 1.84) on platinum under the See also:

• INFLUENCE (Late Lat. influentia, from influere, to flow in)

influence of an alternating current . A crystalline precipitate is obtained, which is soluble in water and is very hygroscopic . The platinonitrites of composition M2Pt(NO2)4 are mostly obtained by double decomposition from the potassium salt, which is formed by adding a warm aqueous solution of potassium nitrite to one of potassium chlorplatinate . They are mostly colourless or See also:

• PALE (through Fr. pal, from Lat. palms, a stake, for paglus, from the stem pag- of pangere, to fix; " pole " is from the same original source)

pale yellow solids which are more or less soluble in water (L . F . Nilson, Ber., 1876, 9, p . 1722) .

The corresponding platino-oxalates M2Pt(C204)2 were first obtained by J . W . See also:

• DOBEREINER, JOHANN WOLFGANG (178o--1849)

Dobereiner (Pogg . Ann., 1833, 104, p . 18o) and their constitution was determined by H . G . Soderbaum (Ber., 1888, 21, p . 567 R; Zeit. anorg . Chem., 1894, 6, p . 45) . The sodium salt, from which the others are obtained by double decomposition, is formed by adding a warm solution of oxalic acid to sodium platinate . On recrystallization from alkaline solutions the salts are obtained in yellow or orange crystals (see M .

Vezes, Bull. soc. chim., 1898 (3), 19, p . 875) . These salts are scarcely soluble in water and decompose explosively when suddenly heated . The free acid is obtained by decomposing the silver salt with hydrochloric acid, the See also:

• INDIGO (earlier indico, from Lat. indicum, the Indian sub-stance or dye; the Sans. name was niti, from nila, dark blue, and this through Arab. al-nil, annil, gives " aniline ")

indigo See also:

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

blue solution so obtained on concentration in vacuo yielding a red crystalline mass, which dissolves in water with an indigo blue colour, changing to yellow on dilution . Platinum cyanide, Pt(CN)2, is formed by the addition of mercuric cyanide to a solution of a chlorplatinite, or by the decomposition of See also:

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

mercury or ammonium platinocyanide by heat . It is an amorphous powder which is insoluble in water, acids or alkalis, but is soluble in a solution of hydrocyanic acid . It See also:

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

burns when heated . The platinocyanides are derived from the acid H2Pt(CN)6, which is formed by the decomposition of the mercury or copper-salt with sulphuretted hydrogen, or of the barium salt with sulphuric acid . It crystallizes from water in See also:

• CINNABAR (Ger. Zinnober)

cinnabar-red prisms which contain five molecules of water of crystallization; in the anhydrous condition it is of a yellowish green colour . It decomposes carbonates . Its salts, which are characterized by the See also:

• PROPERTY

property of polychroism, may be prepared by the usual methods, or by the solution of metallic platinum in the alkaline cyanides or alkaline See also:

• EARTH
• EARTH (a word common to Teutonic languages, cf. Ger. Erde, Dutch aarde, Swed. and Dan. jord; outside Teutonic it appears only in the Gr. 'pq'e, on the ground; it has been connected by some etymologists with the Aryan root ar-, to plough, which is seen in
• EARTH, FIGURE OF
• EARTH, FIGURE OF THE

earth cyanides under the influence of an alternating current (A . Brochet and J .

See also:

• PETIT, SIR DINSHAW MANECKJI, BART

Petit, Ann. chim. phys., 1904 (8), 3, p . 460; M . See also:

• BERTHELOT, MARCELLIN PIERRE EUGENE (1827–1907)

Berthelot, Comptes rendus, 1904, 138, p . 1130) . Those of the alkali and alkaline earth metals are soluble in water . Many combine with the halogen elements to form complex salts of the type M2Pt(CN)4.C12. x H2O . By the decomposition of the barium salts of this type, addition products of the free acid, of composition H2Pt(CN)4.Cl2.4H2O and H2Pt(CN)s.Br2, have been obtained (C . Blomstrand, Ber., 1869, 2, p . 202) . They are deliquescent solids which are exceedingly soluble in water . Potassium platinocyanide, K2Pt(CN)4.3H20, is obtained by dissolving platinum bichloride in potassium cyanide; by heating potassium ferrocyanide with spongy platinum; or by heating ammonium chlorplatinate with potassium cyanide . It crystallizes in needles which effloresce readily .

The dry salt is exceedingly hygroscopic and is very soluble In water . When boiled with aqua regia it forms the chlorine addition product, K2Pt(CN)4.C12.2H20 . It combines directly with iodine . Barium platinocyanide, BaPt(CN)4.4H20, is prepared by the action of baryta water on the copper salt; by dissolving platinum in barium cyanide under the influence of an alternating current; by the addition of barium cyanide to platinum bichloride; or by the simultaneous action of hydrocyanic and sulphurous acids on a mixture of baryta and chlorplatinic acid (P . Bergsoe, Zeit. anorg . Chem., 1899, 19, p . 318) . It crystallizes in yellow See also:

• MONOCLINIC

monoclinic prisms and is soluble in hot water . It is employed for the manufacture of fluorescent screens used for the detection of X-rays . The platinum salts combine with See also:

• AMMONIA (NH3)

ammonia to form numerous derivatives which can be considered as salts of characteristic bases . The first compound of this type was isolated in 1828 by See also:

• MAGNUS, HEINRICH GUSTAV (1802-1870)

Magnus, who obtained a green salt by the action of ammonia on platinum bichloride . Two See also:

• SERIES (a Latin word from serere, to join)

series of these salts are known, one in which the metal corresponds to bivalent platinum, the other in which it corresponds to tetravalent platinum .

The general formulae of the groups in each series are shown below, the method of See also:

• CLASSIFICATION (Lat. classis, a class, probably from the root cal-, cla-, as in Gr. icaMce, clamor)

classification being that due to See also:

• WERNER, ABRAHAM GOTTLOB (1750-1817)
• WERNER, ANTON ALEXANDER VON (1843– )
• WERNER, FRIEDRICH LUDWIG ZACHARIAS (1768–1823)

Werner . Divalent (platinous) Salts . Tetravalent (platinic) Salts . Hexammine salts[Pt(NH3)e]Xs Tetrammine „ [Pt(NH3)QX2]X2 Triammine „ [Pt(NH3)3X3]X Diammine „ [Pt(NH3)2X41 Monammine „ [Pt(NH3)X3IR In the above table X represents a monovalent acid See also:

• RADICAL (Lat. radix, a root)

radical and R a monovalent basic radical . For methods of preparation of salts of these series see P . T . Cleve, Bull. soc. chim . 1867 et seq.; S . M . Jorgensen, Journ. prak . Chem . 1877 et seq .

; C.W . Blomstrand, Ber . 1871 et seq . ; and A . Werner, Zeit. anorg . Chem . 1893 et seq . A very See also:

• COMPLETE

complete account of the method of classification and the general theory of the metal ammonia compounds is given by A . Werner, Ber . 1907, 40, p . 15 . Platinum also forms a series of complex phosphorus compounds .

At 250° finely divided platinum and phosphorus pentachloride combine to form PtC12.PC13, as dark See also:

• CLARET (from the Fr. vin claret, mod. clairet, wine of a light clear colour, from Lat. clarus, clear)

claret-coloured crystals . With chlorine this substance gives PtC13•PC14 as a yellow powder, and with water it yields phosphoplatinic acid, PtC12.P(OH)3, which may be obtained as orange-red deliquescent prisms . The atomic See also:

• WEIGHT

weight of platinum was determined by K . Seubert (Ann . 1888, 207, p . 1; Ber . 1888, 21, p . 2179) by analyses of ammonium and potassium platinochlorides; the value 194.86 being obtained .