such as furfuracrolein, C,H2O CH:CH·CHO, and furfuracetone, | the fire-place in which the fuel is consumed, the heated chamber, CHO CH:CH CÓ CHỊ. With alcoholic potassium cyanide laboratory, hearth or working bed, as it is variously called, it changes to furoin, CH,O CHOH-CO·C,H2O, which can be oxidized to furil, CH2O·CO·CO-CH2O, whilst alcoholic potash converts it into furfuryl alcohol. With fatty acids and acid anhydrides it gives the "Perkin "reaction (see CINNAMIC ACID). Furfurol is shown to have its aldehydic group in the a position, by conversion into furfurpropionic acid, CH2O-CH2-CH2 CO2H, which on oxidation by bromine water and subsequent reduction of the oxidized product is converted into n-pimelic acid, HO2C(CH2) CO,H. Furfurol in minute quantities can be detected by the red colour it forms with a solution of aniline

where the heat is applied to the special work for which the furnace is designed, and the apparatus for producing rapid combustion by the supply of air under pressure to the fire. In the simplest cases the functions of two or more of these parts may be combined into one, as in the smith's forge, where the fire-place and heating | chamber are united, the iron being placed among the coals, only the air for burning being supplied under pressure from a blowing engine by a second special contrivance, the tuyere, tuiron, twyer or blast-pipe; but in the more refined modern furnaces, where great economy of fuel is an object, the different functions are distributed over separate and distinct apparatus, the fuel being converted into gas in one, dried in another, and heated in a third, before arriving at the point of combustion in the working chamber of the furnace proper.

bustion are employed (1) only for heating purposes, or (2) both for Furnaces may be classified according as the products of comBer.,heating and bringing about some chemical change. The furnaces employed for steam-raising or for heating buildings are invariably of the first type (see BOILER and HEATING), while those employed in metallurgy are generally of the second. The essential difference in construction is that in the first class the substances heated do whereas in the second they do. Metallurgical furnaces of the first not come into contact with either the fuel or the furnace gases, class are termed crucible, muffle or retort furnaces, and of the second shaft and reverberatory furnaces. The following is a detailed subdivision:(1) Fuel and substance in contact.

collect at the lowest point of the hearth, whence they are removed [ally representing its class. The fire-place A is divided from the by opening a hole pierced through the front wall at the bottom. working bed B by a low wall C known as the fire bridge, and at the The active portion of such a furnace is essentially that above the opposite end there is sometimes, though not invariably, a second blast-pipe, the function of the lower part being merely the collection bridge of less height called the flue bridge D. A short diagonal flue of the reduced metal; the fire may therefore be regarded as burning oldianini addo about boloso planla da obara afurbiny) had sudd in an unconfined space, with the waste of a large amount of its siods gnibrocos(sonatedna heating power. By continuing the walls of the hearth above the yal soqqu os paimtel tuyere, into a shaft or stack either (soidgang halo of the same or some other section, inshoqmisviteler alwe obtain a furnace of increased besbainonds to capacity, but with no greater power of consuming fuel, in which the material to be treated can be

aloni bocheated up gradually by loading it into the stack, alternately with layers of fuel, the charge descending regularly to the point of combustion, and absorbing a proportion of the heat of the flame that went to waste in the open dfire. This principle is capable of ara very wide extension, the blast. furnace being mainly limited in height by the strength the column To Beqof materials or "burden" has to resist crushing, under the weight due to the head adopted, and the power of the blowing engine to supply blast of sufficient density to overcome the resistance of the closely packed materials to the free passage of the spent gases. The consuming power of the furnace or the rate at which it can burn the fuel supplied is measured by the number of tuyeres and their section. iq to Jurbo or The development of blast furnaces is practically the develop-e ment of iron-smelting. The profile has been very much varied at different times. The earliest examples were square or rectangular in horizontal section, but the general tendency of modern practice is to substitute round sections, their construction being facilitated by the use of specially moulded bricks which have entirely superseded the sandstone blocks formerly used. The vertical section, on the other hand, is subject to considerable variation according to the work to which the furnace is applied. Where the operation is simply one of fusion, as in the ironfounder's cupola, in which there is no very great change in volume in the materials on their descent to the tuyeres, the stack is nearly or quite straight-sided; but when, as is the case with the smelting of iron ores with limestone flux, a large proportion of volatile matter has to be removed in the process, a wall of varying

inclination is used, so that the body of the furnace is formed of two dissimilar truncated cones, joined by their bases, the lower one passing downwards into a short, nearly cylindrical, position. For further consideration of this subject see IRON AND STEEL.

Hearth furnaces are are employed in certain metallurgical operations, e.g. in the air-reduction process for smelting lead ores. The principle is essentially that of the Catalan forge. Such furnaces are very wasteful, and have little to recommend them (see Schnabel, Metallurgy, 1905, vol. i. p. 409). giantes Reverberatory Furnaces.-Blast furnaces are, from the intimate contact between the burden to be smelted and the fuel, the least wasteful of heat; but their use supposes the possibility of obtain-is ing fuel of good quality and free from sulphur or other substances likely to deteriorate the metal produced. In all cases, therefore, where it is desired to do the work out of contact with the solid fuel, the operation of burning or heat-producing must be performed in a special fire-place or combustion chamber, the body of flame and heated gas being afterwards made to act upon the surface of the material exposed in a broad thin layer in the working bed or laboratory of the furnace by reverberation from the low vaulted roof covering the bed. Such furnaces are known by the general name of reverberatory or reverbatory furnaces, also as air or wind furnaces, to distinguish them from those worked with compressed air or blast. xludgile

Originally the term cupola was used for the reverberatory furnace, but in the course of time it has changed its meaning, and is now given to a small blast furnace such as that used by iron-founders reverberatory smelting furnaces in the same trade being called air furnaces.

Figs. 2, 3 and 4 represent a reverberatory furnace such as is used for the fusion of copper ores for regulus, and may be taken as gener

heat of the body of flame issuing through the fire arch by a passage | immediately in contact with the fuel and flame, such as the to which the air has free access. The material to be melted is lining of the fire-place, the arches, roof and flues, the lower part introduced into the furnace from the hoppers HH through the charging holes in the roof When melted the products separate on if not the whole of the chimney lining in reverberatory furnaces, the bed (which is made of closely packed sand or other infusible and the whole of the internal walls of blast furnaces. Among substances), according to their density; the lighter earthy matters such substances are fireclay and firebricks, certain sandstones, forming an upper layer of slag are drawn out by the slag hole K at silica in the form of ganister, and Dinas stone and bricks, ferric the flue end into an iron wagon or bogie, while the metal subsides to the bottom of the bed, and at the termination of the operation oxide and alumina, carbon (as coke and graphite), magnesia, is run out by the tap hole L into moulds or granulated into water. lime and chromium oxide-their relative importance being The opposite opening M is the working door, through which the tool indicated by their order, the last two or three indeed being only for stirring the charge is introduced. It is covered by a plate of limited use. suspended to a lever, similar to that seen in the end elevation (fig. 4) in front of the slag hole.

The most essential point in good fireclays, or in the bricks or other objects made from them, is the power of resisting According to the purposes to which they are applied, rever-fusion at the highest heat to which they may be exposed. This beratory furnaces may be classed into two groups, namely, fusion supposes them to be free from metallic oxides forming easily or melting furnaces, and calcining or wasting furnaces, also fusible compounds with silica, such as lime or iron, the presence called calciners. The former have a very extended application of the former even in comparatively small proportion being very in many branches of industry, being used by both founders and detrimental. As clays they must be sufficiently plastic to be smelters in the fusion of metals; in the concentration of poor readily moulded, but at the same time possess sufficient stiffness metallic compounds by fusion into regulus; in the reduction not to contract too strongly in drying, whereby the objects. of lead and tin ores; for refining copper and silver; and for produced would be liable to be warped or cracked before firing. making malleable iron by the puddling processes and welding. In most cases, however, the latter tendency is guarded against, Calcining furnaces have a less extended application, being in making up the paste for moulding, by adding to the fresh chiefly employed in the conversion of metallic sulphides into clay a certain proportion of burnt material of the same kind, oxides by continued exposure to the action of air at a temperature such as old bricks or potsherds, ground to a coarse powder. far below that of fusion, or into chlorides by roasting with common Coke dust or graphite is used for the same purpose in crucible salt. As some of these substances (for example, lead sulphide making (see FIREBRICK). and copper pyrites) are readily fusible when first heated, but become more refractory as part of the sulphur is dissipated and oxygen takes its place, it is important that the heat should be very carefully regulated at first, otherwise the mass may become clotted or fritted together, and the oxidizing effect of the air soon ceases unless the fritted masses be broken small again. This is generally done by making the bed of the furnace very long in proportion to its breadth and to the fire-grate area, which may be the more easily done as a not inconsiderable amount of heat is given out during the oxidation of the ore-such increased length being often obtained by placing two or even three working beds one above the other, and allowing the flame to pass over them in order from below upwards. Such calciners are used especially in roasting zinc blende into zinc oxide, and in the conversion of copper sulphides into chlorides in the wet extraction process. In some processes of lead-smelting, where the minerals treated contain sand, the long calciner is provided with a melting bottom close to the fire-place, so that the desulphurized ore leaves the furnace as a glassy slag or silicate, which is subsequently reduced to the metallic state by fusion with fluxes in blast furnaces. Reverberatory furnaces play an important part in the manufacture of sodium carbonate; descriptions and illustrations are given in the article ALKALI MANUFACTURE.

Muffle, Crucible and Retort Furnaces.-A third class of furnaces is so arranged that the work is done by indirect heating; that is, the material under treatment, whether subjected to calcination, fusion or any other process, is not brought in contact either with fuel or flame, but is raised to the proper temperature by exposure in a chamber heated externally by the products of combustion. These are known as muffle or chamber furnaces; and by supposing the crucibles or retorts to represent similar chambers of only temporary duration, the ordinary pot melting air furnaces, and those for the reduction of zinc ores or the manufacture of coal gas, may be included in the same category. These are almost invariably air furnaces, though sometimes air under pressure is used, as, for example, in the combustion of small anthracitic coal, where a current of air from a fan-blower is sometimes blown under the grate to promote combustion. Types of muffle furnaces are figured in the article ANNEALING, HARDENING AND TEMPERING.

Furnace Materials.-The materials used in the construction of furnaces are divisible into two classes, namely, ordinary and refractory or fire-resisting. The former are used principally as casing, walls, pillars or other supporting parts of the structure, and includes ordinary red or yellow bricks, clay-slate, granite and most building stones; the latter are reserved for the parts

The most highly valued fireclays are derived from the Coal Measures. Among the chief localities are the neighbourhood of Stourbridge in Worcestershire and Stannington near Sheffield, which supply most of the materials for crucibles used in steel and brass melting, and the pots for glass houses; Newcastle-on-Tyne and Glenboig near Glasgow, where heavy blast furnace and other firebricks, gas retorts, &c., are made in large quantities. Coarsegrained but very strong firebricks are also made of the waste of china clay works.

In Belgium the clay raised at Andenne is very largely used for making retorts for zinc furnaces. The principal French fireclays are derived from the Tertiary strata in the south, and more nearly resemble porcelain clays than those of the Coal Measures They give wares of remarkably fine texture and surface, combined with high refractory character.

In Germany, Ips and Passau on the Danube, and Gross Almerode in Hesse, are the best known localities producing fireclay goods, the crucibles from the last-mentioned place, known as Hessian crucibles, going all over the world. These, though not showing a great resistance to extreme heat, are very slightly affected by sudden alternations in heating, as they may be plunged cold into a strongly heated furnace without cracking, a treatment to which French and Stourbridge pots cannot be subjected with safety.

Plumbago or graphite is largely used in the production of crucibles, not in the pure state but in admixture with fireclay; the proportion of the former varies with the quality from 25 to nearly 50 %. These are the most enduring of all crucibles, the best lasting out 70 or 80 meltings in brass foundries, about 50 with bronze, and 8 to 10 in steel-melting.

Silica is used in furnace-building in the forms of sand, ganister, a finely ground sandstone from the Coal Measures of Yorkshire, and the analogous substance known as Dinas clay, which is really nearly pure silica, containing at most about 24% of bases. Dinas clay is found at various places in the Vale of Neath in South Wales, in the form of a loose disintegrated sandstone, which is crushed between rollers, mixed with about 1 % of lime, and moulded into bricks that are fired in kilns at a very high temperature. These bricks are specially used for the roof, fire arches, and other parts subjected to intense heat in reverberatory steel-melting furnaces, and, although infusible under ordinary conditions, are often fairly melted by the heat without fluxing or corrosion after a certain amount of exposure. Ganister, a slightly plastic siliceous sand, is similarly used for the lining of Bessemer steel converters; it is found in the neighbourhood of Sheffield.

Alumina as a refractory material is chiefly used in the form of bauxite, but its applications are somewhat special. It has been found to stand well for the linings of rotatory puddling furnaces, where, under long-continued heating, it changes into a substance as hard and infusible as natural emery. In the

its

FURNES (Flem. Veurne), an old-fashioned little town amid the dunes near the coast in West Flanders, Belgium, about 26 m. S.W. of Bruges. Pop. (1904) 6099. It is the centre of a considerable area extending to the French frontier, and market is an important one for the disposal of corn, stock, hops and dairy produce. During the Norman raids Furnes was destroyed, and the present town was built by Baldwin Bras de Fer, first count of Flanders, about the year 870. At the height of the prosperity of the Flemish communes in the 14th century there were dependent on the barony of Furnes not fewer than fifty-two rich villages, but these have all disappeared, partly no doubt as the consequence of repeated French invasions down to the end of the 18th century, but chiefly through the encroachment of the sea followed by the accumulation of sand along the whole of this portion of the coast. Furnes contains many

American

In iron-smelting blast furnaces the waste gases are of considerable fuel value, and may render important services if properly applied. Owing to the conditions of the work, which require the maintenance of a sensibly reducing atmosphere, they contain a very notable proportion of carbonic oxide, and are drawn off by large wrought iron tubes near the top of the furnace and conveyed by branch pipes to the different boilers and air-heating apparatus, which are now entirely heated by the combustion of such gases, or mixed with air and exploded in gas engines. Formerly they were allowed to burn to waste at the mouth of a short chimney place above the furnace top, forming a huge body of flame, which was one of the most striking features of the Black Country landscape at night. Laboratory and Portable Furnaces.-Small air-furnaces with hot plates or sand bath flues were formerly much employed in chemical laboratories, as well as small blast furnaces for crucibles heated with charcoal or coke. The use of such furnaces has very considerably diminished, owing to the general introduction of coal-gas for heating purposes in laboratories, which has been rendered possible by the invention of the Bunsen burner, in which the mixture of air and gas giving the least luminous but most powerfully heating flame is curious old houses and the church of St Walburga, which is a effected automatically by the effluent gas. These burners, or fine survival of the 13th century with some older portions. The modifications of them, have also been applied to muffle furnaces, old church and buildings, grouped round the Grand Place, which which are convenient when only a few assays have to be made the furnace being a mere clay shell and soon brought to a working is the scene of the weekly market, present a quaint picture temperature; but the fuel is too expensive to allow of their being which is perhaps not to be equalled in the country. Near Furnes used habitually or on a large scale. Petroleum, or rather the heavy on the seashore is the fashionable bathing place called La Panne. oils obtained in tar refineries, having an equal or superior heating Furnes one day a year becomes a centre of attraction to all power to coal-gas, may also be used in laboratories for producing the people of Flanders. This is the last Sunday in July, when the high temperatures. The oil is introduced in a thin stream upon a series of inclined and channelled bars, where it is almost immediately fête of Calvary and the Crucifixion is celebrated. Of all popular volatilized and burnt by air flowing in through parallel orifices. festivities in Belgium this is the nearest approach to the old Furnaces of this kind may be used for melting cast iron or bronze Passion Play. The whole story of Christ is told with great in small quantities, and were employed by H. Sainte Claire Deville precision by means of succeeding groups which typify the different in experiments in the metallurgy of the platinum group of metals. Sefstrom's blast furnace, used in Sweden for the assay of iron ores, phases of the subject. The people of Furnes pose as Roman is a convenient form of portable furnace applied to melting in soldiers or Jewish priests, as the apostles or mere spectators, crucibles. It consists of a sheet-iron cylinder about 8 or 9 in. in while the women put on long black veils so that they may figure diameter, within which is fixed one of smaller size lined with fire in the procession as the just women. clay. The space between the two cylinders serves as a heater and distributor for the blast, which is introduced through the nozzle at FURNESS, HORACE HOWARD (1833- " the bottom, and enters the furnace through a series of several small Shakespearian scholar, was born in Philadelphia on the 2nd of tuyeres arranged round the inner lining. Charcoal is the fuel used, November 1833, being the son of William Henry Furness (1802and the crucibles stand upon the bottom of the clay lining. When 1896) minister of the First Unitarian church in that city, a a large body of fuel is required, the cylinder can be lengthened by an iron hoop which fits over the top ring. Deville's portable blast powerful preacher and writer. He graduated at Harvard in furnace is very similar in principle to the above, but the body of the 1854, and was admitted to the bar in 1859, but soon devoted furnace is formed of a single cast iron cylinder lined with fireclay, himself to the study of Shakespeare. He accumulated a collection closed below by a cast iron plate perforated by a ring of small holes of illustrative material of great richness and extent, and brought a hemispherical basin below forming the air-heating chamber. out in 1871 the first volume of a new Variorum edition, designed FURNEAUX, TOBIAS (1735-1781), English navigator, was to represent and summarize the conclusions of the best authorities born at Swilly near Plymouth on the 21st of August 1735. He entered the royal navy, and was employed on the French and in all languages-textual, critical and annotative. The volumes African coasts and in the West Indies during the latter part of the appeared as follows: Romeo and Juliet (1871); Macbeth (1873) (revised edition, 1903); Hamlet (2 vols., 1877); King Lear Seven Years' War (1760-1763). He served as second lieutenant (1880); Othello (1886); The Merchant of Venice (1888); As You of the "Dolphin" under Captain Samuel Wallis on the latter's Like It (1890); The Tempest (1892); A Midsummer Night's voyage round the globe (August 1766-May 1768); was made Dream (1895); The Winter's Tale (1898); Much Ado about a commander in November 1771; and commanded the "Ad- Nothing (1899); Twelfth Night (1901); Love's Labour's Lost venture" which accompanied Captain Cook (in the "Resolu- (1904). The edition has been generally accepted as a thorough tion") in Cook's second voyage. On this expedition Furneaux and scholarly piece of work; its chief fault is that, beginning was twice separated from his leader (February 8-May 19, 1773; with Othello (1886), the editor used the First Folio text as his October 22, 1773-July 14, 1774, the date of his return to basis, while in others he makes the text of the Cambridge (Globe) England). On the former occasion he explored a great part of editors his foundation. His wife, Helen Kate Furness (1837the south and east coasts of Tasmania, and made the earliest 1883), compiled A Concordance to the Poems of Shakespeare (1872). British chart of the same. Most of his names here survive; the major portion of the county by Morecambe Bay. It is FURNESS, a district of Lancashire, England, separated from bounded S.E. by this inlet of the Irish Sea, S.W. by the sea, W. by the Duddon estuary and Cumberland, and N. and E. by Westmorland. Its area is about 250 sq. m. It forms the greater part of the North Lonsdale parliamentary division of Lancashire, and contains the parliamentary borough of Barrow-in-Furness. in the celebrated Lake District, and contains such eminences The surface is almost entirely hilly. The northern half is included Duddon, which forms part of the western boundary, the principal as the Old Man of Coniston and Wetherlam. Apart from the rivers are the Leven and Crake, flowing southward into a common estuary in Morecambe Bay. The Leven drains Windermere and the Crake Coniston Lake. The usage of the term "Lake District," however, tends to limit the name of Furness in common thought to the district south of the Lakes, where several of the place-names are suffixed with that of the district, as Barrow-inFurness, Dalton-in-Furness, Broughton-in-Furness. Between

Cook, visiting this shore-line on his third voyage, confirmed

Furneaux's account and delineation of it (with certain minor

criticisms and emendations), and named after him the islands in Banks Straits, opening into Bass's Straits, and the group now known as the Low Archipelago. After the "Adventure" was finally separated from the "Resolution" off New Zealand in October 1773, Furneaux returned home alone, bringing with him Omai of Ulaietea. This first South Sea Islander seen in the British Isles returned to his home with Cook in 1776-1777. Furneaux was made a captain in 1775, and commanded the Syren "in the British attack of the 28th of June 1776 upon Charleston, South Carolina. His successful efforts to introduce domestic animals and potatoes into the South Sea Islands are worthy of note. He died at Swilly on the 19th of September See Hawkesworth's Narrative of Wallis' Voyage; Captain Cook's Narrative of his Second Voyage; also T. Furneaux's life by Rev. Henry Furneaux in the Dictionary of National Biography.

1781.