See also:

• CALORESCENCE (from the Lat. calor, heat)

CALORESCENCE (from the See also:

• LAT

Lat. calor, 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)  , a See also:

• TERM

term invented by See also:

• JOHN
• JOHN (1167–1216)
• JOHN (1290-c. 1320)
• JOHN (1296-1346)
• JOHN (1371–1419)
• JOHN (1468-1532)
• JOHN (1801-1873)
• JOHN (Heb. llni')
• JOHN (ZAPOLYA) (1487-1540)
• JOHN, 4TH MARQUESS OF TWEEDDALE (c. 1695-1762)
• JOHN, DON (1545-1578)
• JOHN, DON (1629–1679)
• JOHN, GOSPEL OF ST
• JOHN, or HAYS (1513–1571)
• JOHN, THE APOSTLE
• JOHN, THE EPISTLES OF

John See also:

• TYNDALL, JOHN (182o-1893)

Tyndall to describe an See also:

• OPTICAL

optical phenomenon, the essential feature of which is the See also:

• CONVERSION (Lat. conversio, from convertere, to turn or ,change)

conversion of rays belonging to the dark infra-red portion of the spectrum into the more refrangible visible rays, i.e. 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 rays into rays of See also:

• LIGHT

light . Such a transformation had not previously been observed, although the converse phenomenon, i.e. the conversion of See also:

• SHORT, FRANCIS JOB (1857– )

short waves of light into longer or less refrangible waves, had been shown by See also:

• SIR

Sir G . G . See also:

• STOKES, SIR G
• STOKES, SIR GEORGE GABRIEL, BART
• STOKES, WHITLEY (1830-1909)

Stokes to occur in fluorescent bodies . Tyndall's experiments, however, were carried out on quite different lines, and have nothing to do with See also:

• FLUORESCENCE

fluorescence (q.v.) . His method was to sift out the See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

long dark waves which are associated with the short visible waves constituting the light 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 or of the electric arc and to concentrate the former to a See also:

• FOCUS (Latin for " hearth " or " fireplace ")

focus . If the See also:

• EYE
• EYE (O. Eng. edge, Ger. Auge; derived from an Indo-European root also seen in Lat. oc-ulus, the organ of vision (q.v.)

eye was placed at the focus, no sensation of light was observed, although small piecesto incandescence, thus giving rise to visible rays . The experiment is more easily carried out with the electric light than with sunlight, as the former contains a smaller See also:

• PRO

pro-portion of visible rays . According to Tyndall, 90% of the See also:

• RADIATION, THEORY OF

radiation from the electric arc is non-luminous . The arc being struck in the usual way between two carbons, a See also:

• CONCAVE

concave See also:

• MIRROR (through O. Fr. mirour, mod. miroir, from a sup-posed Late Lat. miratorium, from mirari, to admire)

mirror, placed See also:

• CLOSE
• CLOSE (from Lat. clausum, shut)
• CLOSE, MAXWELL HENRY (1822-1903)

close behind it, caused a large See also:

• PART

part of the radiation to be directed through an See also:

• APERTURE (from Lat. aperire, to open)

aperture in the See also:

• CAMERA (a Latin adaptation of Gr. Kagapa, an arched chamber)

camera and concentrated to a focus outside . In front of the aperture were placed a See also:

• PLATE

plate of transparent 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-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, and a See also:

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

flat See also:

• CELL (from Lat. cella, probably from an Indo-European kal —seen in Lat. celare, to hide; another suggestion connects the word with Lat. cera, wax, taking the original meaning to refer to the honeycomb)

cell of thin 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 containing a See also:

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

solution of See also:

• IODINE (symbol I, atomic weight '26.92)

iodine in See also:

• CARBON (symbol C, atomic weight 12)

carbon bisulphide . Both rock-salt and carbon 'bisulphide are extremely transparent to the luminous and also to the infra-red rays The iodine in the solution, however, has the See also:

• PROPERTY

property of absorbing the luminous rays, while transmitting the infra-red rays copiously, so that in sufficient thicknesses the solution appears nearly See also:

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

black .

Owing to the inflammable nature of carbon bisulphide, the plate of rock-salt was found to be hardly a sufficient See also:

• PROTECTION

protection, and Tyndall surrounded the iodine cell with an See also:

• ANNULAR, ANNULATE

annular See also:

• VESSEL (O. Fr. vaissel, from a rare Lat. vascellum, dim. of vas, vase, urn)

vessel through which 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 See also:

• WATER

water was made to flow . Any small See also:

• BODY

body which was a goqd absorber of dark rays was rapidly heated to redness when placed at the focus . Platinized See also:

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

platinum (platinum See also:

• FOIL

foil upon which a thin film of platinum had been deposited electrolytically) and See also:

• CHARCOAL

charcoal were rendered incandescent, black See also:

• PAPER
• PAPER (Fr. papier, from Lat. papyrus)

paper and matches immediately inflamed, See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary 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 paper pierced and burned, while thin 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 blotting-paper, owing to its transparency to the invisible rays, was scarcely tinged . A simpler arrangement, also employed by Tyndall, is to cause the rays to be reflected outwards parallel to one another, and to concentrate them by means of a small See also:

• FLASK

flask, containing the iodine solution and used as a See also:

• LENS
• LENS (from Lat. lens, lentil, on account of the similarity of the form of a lens to that of a lentil seed)

lens, placed some distance from the camera . The rock-salt and cold water circulation can then be dispensed with . Since the rays used by Tyndall in these experiments are similar to those emitted bya heated body which is not hot enough to be luminous, it might be thought that the radiation, say from a hot See also:

• KETTLE, SIR RUPERT ALFRED (1817-1894)

kettle, could be concentrated to a focus and employed to render a small body luminous . It would, however, be impossible by such means to raise the receiving body to a higher temperature than the source of radiation . For it is easy to see that if, by means of lenses of rock-salt or mirrors, we focused all or nearly all the rays from a small See also:

• SURFACE

surface on to another surface of equal See also:

• AREA

area, this would not raise the temperature of the second surface above that of the first; and we could not obtain a greater concentration of rays from a large heated surface, since we could not have all parts of the surface simultaneously in focus . The desired result could be obtained if it were possible, by reflection or otherwise, to cause two different rays to unite without loss and pursue a See also:

• COMMON

common path . Such a result must be regarded as impossible of attainment, as it would imply the possibility of heat passing from one body to another at a higher temperature, contrary to the second 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 See also:

• THERMODYNAMICS (from Gr. Bepµos, hot, Siva trs, force)

thermodynamics (q.v.) . Tyndall used the dark rays from a luminous source, which are emitted in a highly concentrated See also:

• FORM (Lat. forma)

form, so that it was possible to obtain a high temperature, which was, however, much See also:

• LOWER

lower than that of the source . A full See also:

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

account of Tyndall's experiments will be found in his Heat, a Mode of See also:

• MOTION (Lat. motio, from movere, to move)
• MOTION, LAWS OF

Motion .

(J . R .