See also:

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

ATMOSPHERE (Gr. See also:

• FIR

fir µ6r, vapour; orkaipa, a See also:

• SPHERE (Gr. vclsa?pa, a ball or globe)

sphere)  , the aeriform envelope encircling 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; also the envelope of a particular See also:

• GAS

gas or gases about any solid or liquid . Meteorological phenomena seated more directly in the See also:

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

atmosphere obtained See also:

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

early recognition; thus See also:

• HESIOD

Hesiod, in his See also:

• WORKS

Works and Days, speculated on the origin of winds, ascribing them to the See also:

• HEATING

heating effects of 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 on the See also:

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

air . Ctesibius of See also:

• ALEXANDRIA
• ALEXANDRIA (Arab. Iskenderia)

Alexandria, See also:

• HERO (Gr. open)
• HERO, THE YOUNGER

Hero and others, founded the See also:

• SCIENCE (Lat. scientia, from scire; to learn, know)

science of See also:

• PNEUMATICS (Gr. Irveiiµa, wind, air)

pneumatics on observations , on the See also:

• PHYSICAL

physical properties of air . Anaximenes made air the primordial substance, and it was one of the Aristotelian elements . A See also:

• DIRECT

direct See also:

• PROOF (in M. Eng. preove, proeve, preve, &°c., from O. Fr . prueve, proeve, &c., mod. preuve, Late. Lat. proba, probate, to prove, to test the goodness of anything, probus, good)

proof of its material nature was given by Galileo, who weighed a See also:

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

copper See also:

• BALL (in Mid. Eng. bal; the word is probably cognate with " bale," Teutonic in origin, cf. also Lat. falls, and Gr. 7raXXa)
• BALL, JOHN (1585-1640)
• BALL, JOHN (1818-1889)
• BALL, JOHN (d. 1381)
• BALL, SIR ALEXANDER JOHN, BART
• BALL, THOMAS (1819- )

ball containing compressed air . Before the development of pneumatic See also:

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

chemistry, air was regarded as a distinct chemical unit or See also:

• ELEMENT (Lat. elementum)

element . The study of calcination and See also:

• COMBUSTION (from the Lat. comburere, to burn up)

combustion during the 17th and 18th centuries culminated in the See also:

• DISCOVERY

discovery that air consists chiefly of a mixture of two gases, See also:

• OXYGEN (symbol 0, atomic weight 16)

oxygen and See also:

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

nitrogen . See also:

• CAVENDISH
• CAVENDISH, GEORGE (1500-1562?)
• CAVENDISH, HENRY (1731-1810)
• CAVENDISH, SIR WILLIAM (c. 1505-1557)

Cavendish, See also:

• PRIESTLEY, JOSEPH (1733-1804)

Priestley, See also:

• LAVOISIER, ANTOINE LAURENT (1743-1794)

Lavoisier and others contributed to this result . Cavendish made many analyses: from more than 500 determinations of air in See also:

• WINTER, JOHN STRANGE
• WINTER, PETER (c. 1755-1825)

winter and summer, in wet and clear See also:

• WEATHER (O. Eng. weder; the word is common to Teutonic languages; cf. Du. weder, Dan. veir, Icel. ve8r, and Ger. Wetter and Gewitter, storm; the root is wa- to blow, from which is derived " wind ")

weather, and in See also:

• TOWN

town and See also:

• COUNTRY (from the Mid. Eng. contre or contrie, and O. Fr. cuntree; Late Lat. contrata, showing the derivation from contra, opposite, over against, thus the tract of land which fronts the sight, cf. Ger. Gegend, neighbourhood)

country, he discerned the mean See also:

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

composition of the atmosphere to be, oxygen 20.833 % and nitrogen 79.167 % The same experimenter noticed the presence of an inert gas, in very See also:

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

minute amount ; this gas, afterwards investigated by See also:

• RAYLEIGH, JOHN WILLIAM STRUTT

Rayleigh and 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, is.now named See also:

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

argon (q.v.) . The constancy of composition shown by repeated analyses of atmospheric air led to the view that it was a chemical See also:

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

compound of nitrogen and oxygen; but there was no experimental See also:

• CONFIRMATION (Lat. confirmatio, from confirmare, to establish, make firm)

confirmation of this See also:

• IDEA (Gr. Ibia, connected with i&eiv, to see; cf. Lat. species from specere, to look at)

idea, and all observations tended to the view that it is simply a See also:

• MECHANICAL

mechanical mixture . Thus, the gases are not See also:

• PRESENT

present in See also:

• SIMPLE

simple multiples of their combining weights; atmospheric air results when oxygen and nitrogen are mixed in the prescribed ratio, the mixing being unattended by any manifestation of See also:

• ENERGY (from the Gr. ivipyela; iv, in, ipyov, work)

energy, such as is invariably associated with a chemical See also:

• ACTION

action; the gases may be mechanically separated by See also:

• ATMOLYSIS (Gr. arµos, vapour: XGecv, to loosen)

atmolysis, i.e. by taking See also:

• ADVANTAGE

advantage of the different rates of See also:

• DIFFUSION (from the Lat. diffundere; dis-, asunder, and fundere, to pour out)

diffusion of the two gases; the solubility of air in See also:

• WATER

water corresponds with the " See also:

• LAW
• LAW (0. Eng. lagu, M. Eng. lawe; from an old Teutonic root lag, " lie," what lies fixed or evenly; cf. Lat. lex, Fr. loi)
• LAW, JOHN (1671—1729)
• LAW, WILLIAM (1686-1761)

law of partial pressures," each gas being absorbed in amount proportional to its pressure and coefficient of absorption, and oxygen being much more soluble than nitrogen (in the ratio of •04114 to •02035 at o''); air expelled from water by boiling is always richer in oxygen . Various agencies are at See also:

• WORK

work tending to modify the composition of the atmosphere, but these so neutralize each other as to leave it practically unaltered .

Minute See also:

• VARIATIONS
• VARIATIONS, CALCULUS
• VARIATIONS, CALCULUS OF

variations, however, do occur . See also:

• BUNSEN, CHRISTIAN CHARLES JOSIAS, BARON VON (1791-186o,)
• BUNSEN, ROBERT WILHELM VON (1811-1899)

Bunsen analysed fifteen examples of air collected at the same See also:

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

place at different times, and found the extreme range in the percentage of oxygen to be from 2o•97 to 2o•84 . See also:

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

Regnault, from analyses of the air of See also:

• PARIS
• PARIS (also called ALEXANDROS)
• PARIS, ALEXIS PAULIN (1800-x881)
• PARIS, BRUNO PAULIN GASTON (1839-1903)
• PARIS, FRANCOIS DE (169o-1727)
• PARIS, LOUIS PHILIPPE ALBERT
• PARIS, TREATIES OF (1814-1815)

Paris, obtained a variation of 2o•999 to 20.913; country air varied from 20 903 to 21.000; while air taken from over the See also:

• SEA (in O. Eng. sae, a common Teutonic word; cf. Ger. See, Dutch Zee, &c.; the ultimate source is uncertain)
• SEA, COMMAND OF THE

sea showed an extreme variation of 20.940 to 20.850 . See also:

• ANGUS, EARLS OF

Angus See also:

• SMITH
• SMITH, ADAM (1723–1790)
• SMITH, ALEXANDER (183o-1867)
• SMITH, ANDREW JACKSON (1815-1897)
• SMITH, CHARLES EMORY (1842–1908)
• SMITH, CHARLES FERGUSON (1807–1862)
• SMITH, CHARLOTTE (1749-1806)
• SMITH, COLVIN (1795—1875)
• SMITH, EDMUND KIRBY (1824-1893)
• SMITH, G
• SMITH, GEORGE (1789-1846)
• SMITH, GEORGE (184o-1876)
• SMITH, GEORGE ADAM (1856- )
• SMITH, GERRIT (1797–1874)
• SMITH, GOLDWIN (1823-191o)
• SMITH, HENRY BOYNTON (1815-1877)
• SMITH, HENRY JOHN STEPHEN (1826-1883)
• SMITH, HENRY PRESERVED (1847– )
• SMITH, JAMES (1775–1839)
• SMITH, JOHN (1579-1631)
• SMITH, JOHN RAPHAEL (1752–1812)
• SMITH, JOSEPH, JR
• SMITH, MORGAN LEWIS (1822–1874)
• SMITH, RICHARD BAIRD (1818-1861)
• SMITH, ROBERT (1689-1768)
• SMITH, SIR HENRY GEORGE WAKELYN
• SMITH, SIR THOMAS (1513-1577)
• SMITH, SIR WILLIAM (1813-1893)
• SMITH, SIR WILLIAM SIDNEY (1764-1840)
• SMITH, SYDNEY (1771-1845)
• SMITH, THOMAS SOUTHWOOD (1788-1861)
• SMITH, WILLIAM (1769-1839)
• SMITH, WILLIAM (c. 1730-1819)
• SMITH, WILLIAM (fl. 1596)
• SMITH, WILLIAM FARRAR (1824—1903)
• SMITH, WILLIAM HENRY (1808—1872)
• SMITH, WILLIAM HENRY (1825—1891)
• SMITH, WILLIAM ROBERTSON (1846-'894)

Smith determined See also:

• LONDON

London air to vary in oxygen content from 2o•857 to 20.95, the air in parks and open spaces showing the higher percentage; See also:

• GLASGOW

Glasgow air showed similar results, varying from 20.887 in the streets to 2o•929 in open spaces . In addition to nitrogen and oxygen, there are a number of other gases and vapours generally present in the atmosphere . Of these, argon and its See also:

• ALLIES, THOMAS WILLIAM (1813-1903)

allies were the last to be definitely isolated . See also:

• CARBON (symbol C, atomic weight 12)

Carbon dioxide is invariably present, as was inferred by Dr See also:

• DAVID
• DAVID (a Hebrew name meaning probably beloved 1)
• DAVID, FELICIEN (1810—1876)
• DAVID, GERARD [GHEERAERT DAVIT], (?=1523)
• DAVID, PIERRE JEAN (1789–1856)
• DAVID, ST (Dewi, Sant)

David Macbride (1726–1778) of See also:

• DUBLIN

Dublin in 1764, but in a See also:

• PRO

pro-portion which is not absolutely See also:

• CONSTANT, BENJAMIN (1845-1902)

constant; it tends to increase at See also:

• NIGHT

night, and during dry winds and fogs, and it is greater in towns than in the country and on See also:

• LAND

land than on the sea . Water vapour is always present; the amount is determined by See also:

• INSTRUMENTS

instruments termed hygrometers (q.v.) . See also:

• OZONE

Ozone (q.v.) occurs, in an amount supposed to be associated with the development of atmospheric See also:

• ELECTRICITY

electricity (See also:

• LIGHTNING

lightning, &c.); this amount varieswith the seasons, being a maximum in See also:

• SPRING (from " to spring," " to leap or jump up," " burst out," O. Eng., springau, a common Teut. word, cf. Ger. springer, possibly allied to Gr. QnrFpxecOac, to move rapidly)

spring, and decreasing through summer and autumn to a minimum in winter . See also:

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

Hydrogen dioxide occurs in a manner closely resembling ozone . Nitric See also:

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

acid and See also:

• LOWER

lower nitrogen oxides are present, being formed by See also:

• ELECTRICAL
• ELECTRICAL (or ELECTROSTATIC) MACHINE

electrical discharges, and by the oxidation of atmospheric See also:

• AMMONIA (NH3)

ammonia by ozone . The amount of nitric acid varies from place to place; See also:

• RAIN (O.E. regn; the word is common to Teutonic languages, cf. Ger. Regen, Swed. and Dan. regn; it has been connected with Lat. rigare, to wet, Gr. 13pixeav)

rain-water, collected in the country, has been found to contain an See also:

• AVERAGE

average of 0•5 parts in a million, but town rain-water contains more, the greater amounts being present in the more densely populated districts .

Ammonia is also present, but in very varying amounts, ranging from 135 to 0•1 parts (calculated as carbonate) in a million parts of air . Ammonia is carried back to the See also:

• SOIL

soil by means of rain, and there plays an important See also:

• PART

part in. providing nitrogenous See also:

• MATTER

matter which is after-wards assimilated by See also:

• VEGETABLE

vegetable See also:

• LIFE

life . The average See also:

• VOLUME

volume composition of the gases of the atmosphere may be represented (in parts per 1o,000) as follows: Oxygen . . . . 2065.94 Ozone . . . 0.015 Nitrogen . . 7711.60 Aqueous vapour 140.00 Argon (about) . . 79.00 Nitric acid . . o•o8 Carbon dioxide . 3.36 Ammonia . . 0.005 In addition to these gases, there are always present in the atmosphere many micro-organisms or bacteria (see See also:

• BACTERIOLOGY

BACTERIOLOGY); another invariable constituent is dust (q.v.), which plays an important'part in meteorological phenomena .

Reference should be made to the articles See also:

• BAROMETER (from Gr. (3apoc, pressure, and µETpov, measure)

BAROMETER, See also:

• CLIMATE

CLIMATE and See also:

• METEOROLOGY (Gr. JerEwpa, and hb'yos, i.e. the science of things in the air)

METEOROLOGY for the measurement and variation of the pressure of the atmosphere, and the discussion of other properties .