See also:

• HELIUM (from Gr. i)Xcor, the sun)

HELIUM (from Gr. i)Xcor, 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)  , a gaseous chemical See also:

• ELEMENT (Lat. elementum)

element, the See also:

• MODERN

modern See also:

• DISCOVERY

discovery of which followed closely on that of See also:

• ARGON (from the Gr. 6.-, privative, and Epyov, work; hence meaning " inert ")

argon (q.v.) . The investigations of See also:

• LORD
• LORD (O. Eng. hldford, i.e. hldfweard, the warder or keeper of bread, hlIf, loaf; the word is not represented in any other Teutonic language)
• LORD, JOHN (1810-1894)

Lord See also:

• RAYLEIGH, JOHN WILLIAM STRUTT

Rayleigh and 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:

• RAMSAY, ALLAN (1686-1758)
• RAMSAY, ALLAN (1713-1784)
• RAMSAY, ANDREW MICHAEL (1686-1743)
• RAMSAY, DAVID (1749—1815)
• RAMSAY, SIR WILLIAM (1852– )
• RAMSAY, SIR WILLIAM MITCHELL (185r– )

Ramsay had shown that indifference to chemical reagents did not sufficiently characterize an unknown See also:

• GAS

gas as See also:

• NITROGEN [symbol N., atomic weight 14.01, 0=16]

nitrogen, and it became necessary to reinvestigate other cases of the occurrence of "nitrogen" in nature . H . Miers See also:

• DREW
• DREW, SAMUEL (1765-1833)

drew Ramsay's See also:

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

attention to the See also:

• WORK

work of W F . See also:

• HILLEBRAND, KARL (1829–1884)

Hillebrand, who had noticed, in examining the See also:

• MINERAL

mineral uraninite, that an inert gas was evolved when the mineral was decomposed with See also:

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

acid . Ramsay, repeating these experiments, found that the inert gas emitted refused to oxidize when sparked with See also:

• OXYGEN (symbol 0, atomic weight 16)

oxygen, and on examining it spectroscopically he saw that the spectrum was not that of argon, but was characterized by a See also:

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

bright yellow See also:

• LINE

line near to, but not identical with, the D line of See also:

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

sodium . This was after-wards identified with the D3 line of the See also:

• SOLAR, SOLLER (Lat. solarium, Fr.• galetas, Ital. solaio)

solar See also:

• CHROMOSPHERE (from Gr. xpwµa, colour, and vqSaipa, a sphere)

chromosphere, observed in 1868 by Sir J . See also:

• NORMAN
• NORMAN, SIR HENRY WYLIE (1826-1904)

Norman See also:

• LOCKYER, SIR JOSEPH NORMAN (1836– )

Lockyer, and ascribed by him to a hypothetical element See also:

• HELIUM (from Gr. i)Xcor, the sun)

helium . This name was adopted for the new gas . Helium is relatively abundant in many minerals, all of which are radioactive, and contain See also:

• URANIUM [symbol U, atomic weight 238.5 (0=16)]

uranium or See also:

• THORIUM (symbol Th, atomic weight ,232.42 [0=16])

thorium as important constituents . (For the significance of this fact see RADIOAcT1~1TY.) The richest known source is See also:

• THORIANITE

thorianite, which consists mainly of thorium See also:

• OXIDE

oxide, and contains 9.5 cc. of helium per See also:

• GRAM

gram . See also:

• MONAZITE

Monazite, a phosphate of thorium and other rare earths, contains on the See also:

• AVERAGE

average about r cc. per gram .

Cleveite, samarskite and fergusonite contain a little more than monazite . The gas also occurs in See also:

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

minute quantities in the See also:

• COMMON

common minerals of the 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's crust . In this See also:

• CASE
• CASE, JOHN (d. 1600)

case too it is associated with radio-active See also:

• MATTER

matter, which is almost ubiquitous . In two cases, how-ever, it has been found in the See also:

• ABSENCE (Lat. absentia)

absence of appreciable quantities of uranium and thorium compounds, namely in See also:

• BERYL

beryl, and in sylvine (See also:

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

potassium chloride) . Helium is contained almost universally in the gases which bubble up with the See also:

• WATER

water of thermal springs . The proportion varies greatly . In the hot springs of See also:

• BATH
• BATH, THOMAS THYNNE
• BATH, WILLIAM

Bath it amounts to about one-thousandth See also:

• PART

part of the gas evolved . Much larger percentages have been recorded in some See also:

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

French springs (Compt. rend., 1906, 143, p . 795, and 146, p . 435), and considerable quantities occur in some natural gas (Journ . Amer . Chem .

See also:

• SOC

Soc . 29, p . 1524) . R . J . See also:

• STRUTT, JEDEDIAH (1726-1797)

Strutt has suggested that helium in hot springs may be derived from the disintegration of common rocks at See also:

• GREAT

great depths . Helium is See also:

• PRESENT

present in the See also:

• ATMOSPHERE (Gr. fir µ6r, vapour; orkaipa, a sphere)

atmosphere, of which it constitutes four parts in a million . It is conspicuous by its absorption spectrum in many of the 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 stars . Certain stars and pebulae show a bright line helium spectrum . Much the best See also:

• PRACTICAL

practical source of helium is thorianite, a mineral imported from See also:

• CEYLON

Ceylon for the manufacture of thoria . It dissolves readily in strong nitric acid, and the helium contained is thus liberated . The gas contains a certain amount of See also:

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

hydrogen and oxides of See also:

• CARBON (symbol C, atomic weight 12)

carbon, also traces of nitrogen .

In See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order to get rid of hydrogen, some oxygen is added to the helium, and the mixture exploded by an electric spark . All remaining impurities, including the excess of oxygen, can then be taken out of the gas by Sir See also:

• JAMES
• JAMES (Gr. 'IlrKw,l3or, the Heb. Ya`akob or Jacob)
• JAMES (JAMES FRANCIS EDWARD STUART) (1688-1766)
• JAMES, 2ND EARL OF DOUGLAS AND MAR(c. 1358–1388)
• JAMES, DAVID (1839-1893)
• JAMES, EPISTLE OF
• JAMES, GEORGE PAYNE RAINSFOP
• JAMES, HENRY (1843— )
• JAMES, JOHN ANGELL (1785-1859)
• JAMES, THOMAS (c. 1573–1629)
• JAMES, WILLIAM (1842–1910)
• JAMES, WILLIAM (d. 1827)

James See also:

• DEWAR, SIR JAMES (1842- )

Dewar's ingenious method of absorption with See also:

• CHARCOAL

charcoal cooled in liquid See also:

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

air . Helium alone refuses to be absorbed, and it can be pumped off from the charcoal in a See also:

• STATE
• STATE, GREAT OFFICERS OF

state of See also:

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

absolute purity . In the absence of liquid air the helium must he purified by the methods employed for argon (q.v.) . If thorianite cannot be obtained, monazite, which is more abundant, may be utilized . A part of the helium contained in minerals can be extracted by 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 grinding (J . A . See also:

• GRAY
• GRAY (or GREY), WALTER DE (d. 1255)
• GRAY, ASA (1810-1888)
• GRAY, DAVID (1838-1861)
• GRAY, ELISHA (1835-1901)
• GRAY, HENRY PETERS (1819-18/7)
• GRAY, HORACE (1828–1902)
• GRAY, JOHN DE (d. 1214)
• GRAY, JOHN EDWARD (1800–1875)
• GRAY, PATRICK GRAY, 6TH BARON (d. 1612)
• GRAY, ROBERT (1809-1872)
• GRAY, SIR THOMAS (d. c. 1369)
• GRAY, THOMAS (1716-1771)

Gray, Proc . See also:

• ROY, WILLIAM (1726-1790)

Roy . Soc., 1909, 82A, p . 301) . Properties.--All attempts to make helium enter into See also:

• STABLE

stable chemical See also:

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

union have hitherto proved unsuccessful .

The gas is in all See also:

• PROBABILITY (Lat. probabilis, probable or credible)

probability only mechanically retained in the minerals in which it is found . Jacquerod and See also:

• PERROT, SIR JOHN (c. 1S27–1592)

Perrot have found that See also:

• QUARTZ

quartz-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 is freely permeable to helium below a red-heat (Comps. rend., 1904, 139, p . 789) . The effect is even perceptible at a temperature as See also:

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

low as 220 C . Hydrogen, and, in a much less degree, oxygen and nitrogen, will also permeate See also:

• SILICA

silica, but only at higher temperatures . They have made this observation the basis of a practical method of separating helium from the other inert gases . M . Travers has suggested that it may explain the liberation of helium from minerals by heat, the gas being enabled to permeate the siliceous materials in which it is enclosed . Thorianite, however, contains no silica, and until it is shown that metallic oxides behave in the same way this explanation must be accepted with reserve . The See also:

• DENSITY (Lat. densus, thick)

density of helium has been determined by Ramsay and Travers as 1.98 . Its ratio of specific heats has very nearly the ideal value 1.666, appropriate to a monatomic See also:

• MOLECULE (from mod. Lat. molecula, the diminutive of moles, a mass)

molecule . The accepted atomic See also:

• WEIGHT

weight is accordingly 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 the density, i.e.approximately four times that of hydrogen .

The refractivity of helium is 0.1238 (air= 1) . The solubility in water is the lowest known, being, at 18.2°, only •0093 vols. per unit See also:

• VOLUME

volume of water . The viscosity is .96 (air= I) . The spectrum of helium as observed in a See also:

• DISCHARGE (adapted from the O. Fr. discharge, modern decharge, from a med. Lat. discargare, to unload, dis- and earn care, to load, cf. " charge ")

discharge See also:

• TUBE (Lat. tuba)

tube is distinguished by a moderate number of brilliant lines, distributed over the whole visual spectrum . The following are the approximate See also:

• WAVE

wave-lengths of the most brilliant lines: Red . . .. 7066 Red .. . . 6678 Yellow . . . 5876 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 . . .

4922 See also:

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

Blue . . . . 4472 See also:

• VIOLET

Violet .. . . . 4026 When the discharge passes through helium at a pressure of several millimetres, the yellow line 5876 is prominent . At See also:

• LOWER

lower pressures the green line 4922 becomes more conspicuous . At atmospheric pressure the discharge is able to pass through a far greater distance in helium than in the common gases . M . Travers, G . Senter and A . Jacquerod (Phil . Trans .

A . 1903, 200, p . 105) carefully examined the behavour of a See also:

• CONSTANT, BENJAMIN (1845-1902)

constant volume gas thermometer filled with helium . For the pressure coefficient per degree, between o° and See also:

• ROE (or Row), SIR THOMAS (c. 1581—1644)
• ROE, EDWARD PAYSON (1838-1888)

roe C., they give the value •00366255, when the initial pressure is 700 mm . This value is indistinguishable from that which they find for hydrogen . Thus at high temperatures a helium thermometer is of no See also:

• SPECIAL

special See also:

• ADVANTAGE

advantage . At low temperatures, on the other See also:

• HAND
• HAND (a word common to Teutonic languages; cf. Ger. Hand, Goth. handus)
• HAND, FERDINAND GOTTHELF (1786-185r)

hand, they find, using an initial pressure of r000 mm., that the temperatures on the helium See also:

• SCALE
• SCALE (1) A

scale are measurably higher than on the hydrogen scale, owing to the more perfectly gaseous See also:

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

condition of helium . This difference amounts to about i1b at the temperature of liquid oxygen, and about *° at that of liquid hydrogen . The liquefaction of helium was achieved by H . Kamerlingh Onnes at See also:

• LEIDEN

Leiden in 1908 . According to him its boiling point is 4.3° abs . (–268.7° C.), the density of the liquid 0.154, the See also:

• CRITICAL (in alphabetical order of authors)

critical temperature 5° abs., and the critical pressure 2.3 atmospheres (Communications from the See also:

• PHYSICAL

Physical Laboratory at Leiden, No. ro8; see also LIQUID GASES) .