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such as furfuracrolein, C,H,O-CH:CH-CHO, and furfuracelone,'| the fire-place in which the fuel is consumed, the heated chamber, C,H,O.CH:CH.CO.CHs. With alcoholic potassium cyanide laboratory, hcarth or working bed, as it is variously called, it changes to furoin, C,H,O.CHOH.CO.C,H,O, which can be where the heat is applied to the special work for which the furnace oxidized to furil, C,H,O.CO.CO-C,H,O, whilst alcoholic potash is designed, and the apparatus for producing rapid combustion converts it into furfuryl alcohol. With fatty acids and acid by the supply of air under pressure to the fire. In the simplest anhydrides it gives the " Perkin " reaction (see CINNAMIC ACID). cases the functions of two or more of these parts may be combined Furfurol is shown to have its aldehydic group in the a position, into one, as in the smith's forge, where the fire-place and heating by conversion into furfurpropionic acid, C.H30-CH2-CH2CO,H, chamber are united, the iron being placed among the coals, only which on oxidation by bromine water and subsequent reduction the air for burning being supplied under pressure from a blowing of the oxidized product is converted into 3-pimelic acid, engine by a second special contrivance, the tuyere, tuiron, HO,C(CH3),CO,H. Furfurol in minute quantities can be iwyer or blast-pipe; but in the more refined modern furnaces, detected by the red colour it forms with a solution of aniline where great economy of fuel is an object, the different functions acetate.
are distributed over separate and distinct apparatus, the fuel Furfurane-aa'. dicarboxylic acid dehydroniocic acid, being converted into gas in one, dried in another, and heated C.H2O(CO,H), is formed when mucic acid is heated with hydro- in a third, before arriving at the point of combustion in the chloric acid at 100° C. On being heated, it loses carbon dioxide working chamber of the furnace proper. and gives pyromucic acid. By, digesting acetoacetic ester with sodium succinate and acetic anhydride, methronic acid, CsH2O bustion are employed (!)
only for heating purposes, or (2) both for
Furnacés may be classified according as the products of com. is obtained; for the constitution of this acid, see Lu Knorr, Ber., heating and bringing about some chemical change. The furnaces 1889, 22, p. 152, and R. Fittig, Ann., 1889, 250, p. 166. Di and tetrahydrofurfura ne compounds are also known (see employed for steam-raising or for heating buildings are invariably
of the first type (see BOILER and HEATING), while those employed A. Lipp. Ber., 1889, 22, p. 1196; W. H. Perkin, junr. Journ. Chem. Soc., 1890, 57, p. 944; and S. Ruhemann, ibid., 1896, 69, p. 1383).
in metallurgy are generally of the second. The essential difference
in construction is that in the first class the substances heated do FURIES (Lat. Furiae, also called DIRAE), in Roman mythology whereas in the second they do. Metallurgical furnaces of the first
not come into contact with either the fuel or the furnace gases, an adaptation of the Greek Erinyes (9.0.), with whom they class are termed crucible, muffle or retort furnaces, and of the are generally identical. A special aspect of them in Virgil is second shalt and reverberatory surnaces. The following is a detailed that of agents employed by the higher gods to stir up mischief, subdivision: strise and hatred upon earth. Mention may here be made of
(1) Fuel and substance in contact.
(6) Height of furnace greater than diameter = shaft furnaces. an old Italian deity Furina (or Furrina), whose worship fell
(a) No blast = kilns. early into disuse, and who was almost forgotten in the time of
(8) With blast = blast furnaces. Varro. By the mythologists of Cicero's time the name was (6) Height not much greater than diameter = hearth furnaces. connected with the verb surere and the noun furia, which in the
(2) Substance heated by products of combustion=reverberatory
furnaces. plural (not being used in the singular in this sense) was accepted
(a) Charge not melted = roasting or calcining furnaces. as the equivalent of the Greek Erinyes. But it is more probably (b) Charge melted = melting furnaces. related to survus, suscus, and signifies one of the spirits of dark (3) Substance is not directly heated by the fuel or by the products ness, who watched over men's lives and haunted their abodes.
of combustion. This goddess had her own special priest, a grove across the Tiber
(2) Heating chamber fixed and forming part of furnace
muffie furnaces. where Gaius Gracchus was slain, and a festival on the 25th of (6) Crucible furnaces. July. Authorities differ as to the existence of more than one (c) Retort furnaces. goddess called Furina, and their identity with the Forinae Another classification may be based upon the nature of the heating mentioned in two inscriptions found at Rome (C.I.L. vi. agent, according as it is coal (or some similar combustible) oil, gas 422 and 10,209).
or electricity. In this article the general principles of metallurgical FURLONG (from the 0. Eng. furlang, i.e. "furrow-long "), is treated in the article Fuel, and of the electric furnace in the
furnaces will be treated; the subject of gas- and oil-heated furnaces a measure of length, originally the length of a surrow in the article ELECTROMETALLURGY. For special surnaces reference should common field system. As the field in this system was
he made to the articles on the industry concerned, e.g. Glass, Gas. generally taken to be a square, 10 acres in extent, and as the Manufacture, &c. acre varied in different districts and at different times, the Shaft, Blasi and Hearlh Furnaces.—The blast furnace in its furlong"
" also varied. The side of a square containing 10 simplest form is among the oldest, if not the oldest, of metalstatute acres is 220 yds. or 40 poles, which was the usually lurgical contrivances. In the old copper-smelting district of accepted length of the furlong. This is also the length of fth of Arabia Petraea, clay blast-pipes dating back to the earlier the statute mile. “Furlong was as early as the 9th century dynasties of ancient Egypt have been found buried in slag heaps; used to translate the Latin stadium, Ith of the Roman mile. and in India the native smiths and iron-workers continue to use
FURNACE, a contrivance for the production and utilization furnaces of similar types. These, when reduced to their most of heat by the combustion of fuel. The word is common to all simple expression, are mere basin-shaped hollows in the ground, the Romance tongues, appearing in more or less modified forms containing ignited charcoal and the substances to be heated, of the Latin fornax. But in all those languages the word has a the fire being urged by a blast of air blown in through one or more extended meaning than in English, as it covers every more nozzles from a bellows at or near the top. They are variety of heating apparatus; while here, in addition to furnaces essentially the same as the smith's forge. This class of furnace proper, we distinguish other varieties as ovens, sloves and kilns. is usually known as an open fire or hearth, and is represented in The first of these, in the form Ojen, is used in German as a general a more advanced stage of development by the Catalan, German term like the French four; bui in English it has been restricted and Walloon forges formerly used in the production of malleable to those apparatus in which only a moderate temperature, iron. usually below a red heat, is produced in a close chamber.
Fig. 1 represents a Catalan forge. The cavity in the ground is bakers' ovens, hot-air ovens or stoves, annealing ovens for glass represented by a pit of square or rectangular section lined with or metal, &c., would all be called fours in French and Öfen in brick or stone of a kind not readily acted on by heat, about 11 or German, in common with furnaces of all kinds. Stove, an 2 st. deep. usually somewhat larger above than below, with a tuyere equivalent of oven, is from the German Stube, i.c. a heated room, with a considerable downward inclination, so that the air meets
or blast-pipe of copper penetrating one of the walls near the top. and is commonly so understood; but is also applied to open the fuel some way down. In iron-smelting the ore is laid in a heap fire-places, which appears to be somewhat of a departure from upon the fuel (charcoal) filling up the hearth, and is gradually brought the original signifcation.
to the metallic state by the reducing action of the carbon monoxide Furnaces are constructed according to many different patterns forming. in the hearth, a spongy mass or ball, which is listed out by
formed at the tuyere. The metal sinks through the ignited fuel, with varying degrees of complexity in arrangement; but all the smelters at the end of cach operation, and carried to the forge may be considered as combining three essential parts, namely, I hammer. The earthy matters form a fusible glass or slag melt, and
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 fue of the reduced metal; the fire may therefore be regarded as burning site interese
เpirin นาฬW) is all in an unconfined space, with the waste of a large amount of its 2293
gibondedor heating power. By continuing the walls of the hearth above the stod ale od CH
A mon but
поімад Солоо \ Діт
IT power of consuming fuel, in which 2161
the material to be treated can be boti bo heated up gradually by loading it
| ansque into the stack, alternately with layers of fuel, the charge descend
SA ing regularly to the point of com
Juod bustion, and absorbing, a proportion of the heat of the flame
70 that went to waste in the open
TOLINI fire. This principle is capable of
has arbato diod Vd Bocor very wide extension, the blast FIG. 1.-Elevation of Catalan furnace being mainly limited in
TOP FIG. 2.–Longitudinal section of Reverberatory Furnace. Forge.
height by the strength the column or up-take E conveys the current of spent flame to the chimney
Sosem to beat of materials or "burden " has to F, which is of square section, diminishing by steps at two or three resist crushing, under the weight due to the head adopted, and the different heights, and provided at the top with a covering plate or power of the blowing engine to supply blast of sufficient density is 40
w galar to overcome the resistance of the closely packed materials to the free passage of the spent gases. The consuming power of the
உயர் Lovaigms eleifs furnace or the rate at which it can burn the fuel supplied is measured
benim bio by the number of tuyeres and their section. ilang 70 Jurb 460
Zooled The development of blast furnaces is practically the develop
7010 ment of iron-smelting. The profile has been very much varied
w oldian st. at different times. The earliest examples were square or rect
osad angular in horizontal section, but the general tendency of modern
bort Battuta practice is to substitute round sections, their construction being
Kad salto alla facilitated by the use of specially moulded bricks which have
10939 zoisibize adı bu
obs entirely superseded the sandstone blocks formerly used. The
Cassando vertical section, on the other hand, is subject to considerable variation according to the work to which the furnace is applied.
ali o HOB9019 Where the operation is simply one of fusion, as in the iron
ob glas founder's cupola, in which
there is no very great change in volume fans in the materials on their descent to the tuyeres, the stack is nearly and FIG. 3.-Reverberatory Furnace (horizontal section).. ghel or quite straight-sided; but when, as is the case with the smelting damper G, which may be raised or lowered by a chain reaching to of iron ores with limestone flux, a large proportion of volatile the ground, and serves for regulating the speed of the exhaust gases, matter has to be removed in the process, a wall of varying
and thereby the draught of air through the fire. Where several inclination is used, so that the body of the furnace is formed of
E ao citosta tieabirols els two dissimilar truncated cones, joined by their bases, the lower than anime or brow yotibdaba one passing downwards into a short, nearly cylindrical,
tood a Dior babivanqui beiblagdel ERIT position. For further consideration of this subject see IRON
ad: zavol 90 busirudqlara bado al AND STEEL.
baby napsadua ei irtos Hearth furnaces are employed in certain metallurgical opera Emil Jeld al azult daw gojzul xd sisset tions, e.g. in the air-reduction process for smelting lead ores.
- The ori ci siaq Iris Mula 293EATE The principle is essentially that of the Catalan forge. Such
946 soitsulle bas oqrob, todo mu furnaces are very wasteful, and have little to recommend them
dicit, that of SUOMUVITARA (see Schnabel, Metallurgy, 1905, vol. i. p. 409).
255617 16 ani
A6 Reverberatory Furnaces.--Blast furnaces are, from the intimate sease totibdi ud anos low contact between the burden to be smelted and the fuel, the least
AD 3 boendua ada seonduba wasteful of heat; but their use supposes the possibility of obtain
Turists and no i sigoord von 2005 Todos ing fuel of good quality and free from sulphur or other substances de Donut odio sistem likely to deteriorate the metal produced. In all cases, therefore, o esbord de dinasta bainod 19 do where it is desired to do the work out of contact with the solid
FR0W Todela, za pidu ona fuel, the operation of burning or heat-producing must be per alime atq3i OJ TOJOT 70 Eldum formed in a special fire-place or combustion chamber, the body in Tolentino ad Homb of flame and heated gas being afterwards made to act upon the rain surface of the material exposed in a broad thin layer in the gogotsus working bed or laboratory of the furnace by reverberation from ប is balsam dorit the low vaulted roof covering the bed. Such furnaces are known
to notare by the general name of reverberatory or reverbatory furnaces, tolddete also as air or wind furnaces, to distinguish them from those
Roitaudam worked with compressed air or blast.
lenia gia 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 Fig. 4.--Reverberatory Furnace (elevation at fue end). iron-founders—reverberatory smelting furnaces in the same furnaces are connected with the same chimney stack, the damper
los trade being called air furnaces.
takes the form of a sliding plate in the mouth of the connecting flue, Figs. 2, 3 and 4 represent a reverberatory furnace such as is used so that the draught in one may be modified without affecting the for the fusion of copper ores for regulus, and may be taken as gener- others. The fire bridge is partially protected against the intense
heat of the body of flame issuing through the fire arch by a passage | immediately in contact with the fuel and fame, such as the introduced into the furnace from the hoppers HH through the lining of the fire-place, the arches, roof and lues, the lower part 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 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 for stirring the charge is introduced. It is covered by a plate of limited use. The opposite opening M is the working door, through which the tool indicated by their order, the last two or three indeed being only suspended to a lever, similar to that seen in the end elevation (hig. 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
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 potsberds, 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 The most highly valued fireclays are derived from the Coal become more refractory as part of the sulphur is dissipated and Measures. Among the chief localities are the neighbourhood of oxygen takes its place, it is important that the heat should be Stourbridge in Worcestershire and Stannington near Sheffield, very carefully regulated at first, otherwise the mass may become which supply most of the materials for crucibles used in steel and
brass melting, and the pots for glass houses; Newcastle-on-Tyne clotted or fritted together, and the oxidizing effect of the air soon and Glenboig near Glasgow, where heavy blast furnace and other ceases unless the fritted masses be broken small again. This is firebricks, gas retorts, &c., are made in large quantities. Coarsegenerally done by making the bed of the furnace very long in grained but very strong firebricks are also made of the waste of proportion to its breadth and to the fire-grate area, which may
china clay works.
In Belgium the clay raised at Andenne is very largely used for be ihe more easily done as a not inconsiderable amount of heat making retorts for zinc furnaces. The principal French fireclays is given out during the oxidation of the ore--such increased are derived from the Tertiary strata in the south, and more nearly length being often obtained by placing two or even three working resemble porcelain clays than those of the Coal Measures They beds one above the other, and allowing the flame to pass over them give wares of remarkably fine texture and surface, combined with
high refractory character. in order from below upwards. Such calciners are used especially
In Germany, Ips and Passau on the Danube, and Gross Almerode in roasting zinc blende into zinc oxide, and in the conversion of in Hesse, are the best known localities producing fireclay goods, the copper sulphides into chlorides in the wet extraction process. In crucibles from the last mentioned place, known as Hessian crucibles, some processes of lead-smelting, where the minerals treated going all over the world. These, though not showing a great resist: contain sand, the long calciner is provided with a melting bottom tions in heating, as they may be plunged cold into a strongly heated
ance to extreme heat, are very slightly affected by sudden alternaclose to the fire-place, so that the desulphurized ore leaves the furnace without cracking, a treatment to which French and Stourfurnace as a glassy slag or silicate, which is subsequently reduced bridge pots cannot be subjected with safety. to the metallic state by fusion with fluxes in blast furnaces. Plumbago or graphite is largely used in the production of Reverberatory furnaces play an important part in the manu- crucibles, not in the pure state but in admixture with fireclay: facture of sodium carbonate; descriptions and illustrations are the proportion of the former varies with the quality from 25 to given in the article ALKALI MANUFACTURE.
nearly 50 %. These are the most enduring of all crucibles, the Muffie, Crucible and Relort Furnaces. -A third class of furnaces best lasting out 70 or 80 meltings in brass foundries, about so is so arranged that the work is done by indirect heating; that with bronze, and 8 to 10 in steel-melting. is, the material under treatment, whether subjected to calcina Silica is used in furnace-building in the forms of sand, ganister, tion, fusion or any other process, is not brought in contact either a finely ground sandstone from the Coal Measures of Yorkshire, with fuel or flame, but is raised to the proper temperature by and the analogous substance known as Dinas clay, which is exposure in a chamber heated externally by the products of really nearly pure silica, containing at most about 23 % of bases. combustion. These are known as muffle or chamber furnaces; Dinas clay is found at various places in the Vale of Neath in and by supposing the crucibles or retorts to represent similar South Wales, in the form of a loose disintegrated sandstone, chambers of only temporary duration, the ordinary pot melting which is crushed between rollers, mixed with about 1 % of lime, air furnaces, and those for the reduction of zinc ores or the and moulded into bricks that are fired in kilns at a very high manufacture of coal gas, may be included in the same category. temperature. These bricks are specially used for the roof, fire These are almost invariably air furnaces, though sometimes air arches, and other parts subjected to intense heat in reverbera. under pressure is used, as, for example, in the combustion of tory steel-melting furnaces, and, although infusible under small anthracitic coal, where a current of air from a fan-blower ordinary conditions, are often fairly melted by the heat without is sometimes blown under the grate to promote combustion. fluxing or corrosion after a certain amount of exposure. Ganister, Types of muffle furnaces are figured in the article ANNEALING, a slightly plastic siliceous sand, is similarly used for the lining HARDENING AND TEMPERING.
of Bessemer steel converters; it is found in the neighbourhood Furnace Materials.-The materials used in the construction of Sheffield, of furnaces are divisible into two classes, namely, ordinary and Alumina as a refractory material is chiefly used in the form refractory or fire-resisting. The former are used principally as of bauxite, but its applications are somewhat special. It has casing, walls, pillars or other supporting parts of the structure, 1 been found to stand well for the linings of rotatory puddling and includes ordinary red or yellow bricks, clay-slate, granite furnaces, where, under long-continued heating, it changes into and most building stones; the latter are reserved for the parts | a substance as hard and infusible as natural emery. In the
Paris Exhibition of 1878 bricks very hard and dense in character, angle of repose of the charge, which is introduced at the upper end, said to be of pure alumina, were exhibited by Muller & Co. of and is pushed down the slope by fresh material, when necessary, Paris, as well as bricks of magnesia, the latter being specially Gerstenhofer's pyrites burner is a furnace of this class. It has a tall remarkable for their great weight. They are intended for use vertical chamber heated from below, and traversed by numerous at the extreme temperatures obtainable in steel furnaces, or narrow horizontal cross bars at different heights. The ore in fine for the melting of platinum before the oxy-hydrogen blowpipe. powder is fed in at the top, through a hopper, in a regular thin For the latter purpose, however, lime is generally used; but as bars, forming a talus upon each of the height corresponding to the this substance has only small stability, it is usually bedded in a angle of rest of the material, which is, however, at short intervals casing of firebrick, Oxide of chromium and chrome iron ore removed to lower levels by the arrival of fresh ore from above. In have been proposed as refractory crucible materials. The formet this way a very large surface is exposed to the heat, and the ore, it may be used as a bed for melting platinum in the same way as burned when it arrives at the bottom; if, however, it is imperfectly
containing sufficient sulphur to maintain the combustion, is perfectly lime or magnesia, without affecting the quality of the metal. sized or damp, or if it contains much earthy matter, the result is
Ferric oxide, though not strictly infusible, is largely used as a not very satisfactory. There are many other furnaces in which the protecting lining for furnaces in which malleable iron is made, same principle is utilized. a portion of the ore being reduced and recovered in the process. furnaces, in which the labour of rabbling or stirring the charges is
2. Mechanical stirrers constitute a second division of mechanical In an oxidizing atmosphere it is indifferent to silica, and therefore performed by combinations of levers and wheel-work taking motion siliceous bricks containing a considerable proportion of ferric from a rotating shaft, and more or less perfectly imitating the action oxide, when used in flues of boilers, brewers' coppers, &c. and of hand labour. They are almost entirely confined to puddling similar situations, are perfectly fire-resisting so long as the heated furnaces. gas contains a large proportion of unconsumed air. The red mechanical furnaces, are of two kinds. The first of these resemble
3. Revolving furnaces, the third and most important division of firebricks known as Windsor bricks, which are practically an ordinary reverberatory furnace by having a fat bed which, similar in composition to soft red sandstone, are of this character. however, has the form of a circular disk mounted on a central shaft,
The electric furnace has led to the discovery of several and receives a slow movement of rotation from a water-wheel or important materials, which have been employed as furnace other motor, so that every part of the surface is brought successively linings. Carborundum (q.v.) was applied by Engels in 1899, removed by passing under a series of Exed scraper arms placed above
under the action of the fire, the charge being stirred and ultimately firebricks being washed with carborundum paste and then baked. the surface at various points. Brunton's calciner, used in the burnSiloxicon, a compound of carbon, silicon and oxygen, formed ing" of the pyritic minerals associated with tin ore, is a familiar from carbon and silica in the electric furnace, was patented by axis, so that the
path of its surface is oblique to that of the fame, E. G. Acheson in 1903. It is very refractory, and is applied by or the working part may be a hollow cylinder, between the fireplace mixing with water and some bond, such as sodium silicate or and flue, with its axis horizontal or nearly so, whose inner surface gas-tar. An amorphous, soft silicon carbide, also formed in the represents the working bed; mounted upon friction rollers, and electric furnace, was patented by B. Talbot in 1899. For basic receiving motion from a special steam-engine by means of a central linings, magnesia crystallized in the electric furnace is being alkali works for the conversion of sulphate into carbonate of sodium
belt of spur gearing. Furnaces of the second kind were first used in extensively used, replacing dolomite to some extent (see E. in the process known as black ash fusion, but have since been applied Kilburn Scott, “Refractory Materials for Furnace Linings,". to other processes. As calciners they are used in tin mines and for Faraday Soc., 1906, P. 289).
the chlorination of silver ores. Mechanical furnaces are figured in Furnace Construction.-In the construction of furnaces provision the article ALKALI MANUFACTURE. has to be made for the unequal expansion of the different parts under
Use of Healed Air.-The calorific intensity of fuel is found to be the effect of heat. This is especially necessary in the case of rever
very considerably enhanced, if the combustion be effected with air beratory furnaces, which are essentially weak structures, and previously heated to any temperature between that of boiling water therefore require to be bound together by complicated systems of and a dull red heat, the same effect being observed both with solid tie rods and uprights or buck staves. The latter are very commonly and gaseous fuel. The latter, especially when brought to the burning made of old Aat bottom rails, laid with the flat of the lange against point at a high temperature, produces a heat that can be resisted the wall. Puddling furnaces are usually entirely cased with iron by the most refractory substances only, such as silica, alumina and. plates, and blast furnaces with hoops round each course of the stack, magnesia. This is attained in the regenerative furnace of Siemens, or in those of thinner constructions the firebrick work
is entirely detailed consideration of which belongs more properly to the subject enclosed in a wrought iron casing or jacket. Such parts as may be of iron. subjected to extreme heat and the fretting action of molten material,
Economy of Wasle Heal.-In every system of artificial heating, the as the tuyere and slag breasts of blast furnaces, and the fire bridges amount of heat usefully applied is but a small proportion of that and bed plates of reverberatory furnaces, are often made in cast developed by combustion. Even under the most advantageous iron with double walls, a current of water or air being kept circulating application, that of evaporation of water in a steam boiler where the through the intermediate space. In this way the metal, owing to gases of the fire have to travel through a great length of flues bounded its high conductivity and low specific heat as compared to that of by thin iron surfaces of great heat-absorbing capacity, the temwater, is kept at a temperature far below its melting point th perature of the current at the chimney is generally much above that water is renewed quickly enough. It is of course necessary in such required to maintain an active draught in the fireplace: and other cases that the circulation shall be perfectly free, in order to prevent tubes containing water, often in considerable numbers, forming the the accumulation of steam under pressure in the interior of the so-called fuel economizers, may often be interposed between the casting. This method has received considerable extension, notably boiler and the chimney with marked advantage as regards saving in furnace-smelting of iron ores containing manganese, where the of fuel. In reverberatory and air furnaces used in the different entire hearth is often completely water-cased, and in some lead operations of iron manufacture, where an extremely high temperature furnaces where no firebrick lining is used, the lower part of the has to be maintained in spaces of comparatively small extent, such furnace stack being a mere double iron box cooled by water suf as the beds of puddling, welding and steel-melting furnaces, the ficiently to keep a coating of slag adhering to the inner shell which temperature of the exhaust gases is exceedingly high, and is allowed prevents the metal from being acted upon.
to pass directly into the chimney they appear as a great body of Mechanical Furnaces.-The introduction and withdrawal of the flame at the top. It is now general to save a portion of this heat by charges in fusion furnaces is effected by gravitation, the solid masses passing the flame through flues of steam boilers, air-heating apparaof raw ore, fuel and Aux being thrown in at the top, and flowing tus, or both-so that the steam required for the necessary operations out of the furnace at the taphole or slag run at the bottom. Vertical of the sorge and heated blast for the furnace itself may be obtained kilns, such as those used for burning limestone, are worked in a without further expenditure of fuel. The most perfect method of similar manner--the raw stone going in at the top, and the burnt utilizing the waste heat hitherto applied is that of the Siemens reproduct falling through holes in the bottom when allowed to do so. generator, in which the spent gases are made to travel through With reverberatory calciners, however, where the work is done chambers, known as regenerators or recuperators of heat, containing upon a horizontal bed, a considerable amount of hand labour is a quantity of thin firebricks piled into a cellular mass so as to offer expended in raking out the charge when finished, and in drawing a very large heat-absorbing surface, whereby their temperature
is slags from fusion furnaces; and more particularly in the puddling very considerably reduced, and they arrive at the chimney at a beat process of refining iron the amount of manual exertion required is not exceeding 300 or 400 degrees. As soon as the bricks have become very much greater. To diminish the item of expenditure on this red hot, the current is diverted to an adjacent chamber or pair of head, various kinds of mechanical furnaces have been adopted, all chambers, and the acquired heat is removed by a current of cool of which can be classified under three heads of gravitating furnaces, gas or air passing towards the furnace, where it arrives at a tem. mechanical stirrers and revolving furnaces.
perature sufficiently high to ensure the greatest possible heating la gravitating furnaces the bed is laid at a slope just within the effect in combustion.
In iron-smelting blast furnaces the waste gases are of considerable FURNES (Flem. Veurne), an old-fashioned little town amid fuel value, and may render important services if properly applied. the dunes near the coast in West Flanders, Belgium, about Owing to the conditions of the work, which require the maintenance of a sensibly reducing atmosphere, they contain a very notable 26 m. S.W. of Bruges. Pop. (1904) 6099. It is the centre of a proportion of carbonic oxide, and are drawn off by large wrought iron considerable area extending to the French frontier, and its tubes near the top of the furnace and conveyed by branch pipes market is an important one for the disposal of corn, stock, hops to the different boilers and air-heating apparatus, which are now
and dairy produce. During the Norman raids Furnes was entirely heated by the combustion of such gases, or mixed with air and exploded in gas engines. Formerly they were allowed to burn destroyed, and the present town was built by Baldwin Bras de to waste at the mouth of a short chimney place above the furnace Fer, first count of Flanders, about the year 870. At the height top, forming a huge body of flame, which was one of the most of the prosperity of the Flemish communes in the 14th century striking features of the Black Country landscape at night.
there were dependent on the barony of Furnes not fewer than Laboratory and Portable Furnaces. --Small air-furnaces with hot plates or sand bath flues were formerly much employed in chemical fifty-two rich villages, but these have all disappeared, partly laboratories, as well as small blast furnaces for crucibles heated with no doubt as the consequence of repeated French invasions down charcoal or coke. The use of such furnaces has very considerably to the end of the 18th century, but chiefly through the encroachdiminished, owing to the general introduction of coal-gas for heating ment of the sea followed by the accumulation of sand along the purposes in laboratories, which has been rendered possible by the invention of the Bunsen burner, in which the mixture of air and gas whole of this portion of the coast. Furnes contains many 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 is the scene of the weekly market, present a quaint picture furnace being a mere clay, shell and soon brought to a working 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 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 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
PURNESS, HORACE HOWARD (1833 American the bottom, and enters the furnace through a series of several small Shakespearian scholar, was born in Philadelphia on the end 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. PURNEAUX, TOBIAS (1735-1781), English navigator, was
out in 1871 the first volume of a new Variorum edition, designed born at Swilly near Plymouth on the 21st of August 1735. He to represent and summarize the conclusions of the best authorities 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) Seven Years' War (1760-1763). He served as second lieutenant (1880); Othello (1886); The Merchant of Venice (1888); As You
(revised edition, 1903); Hamlet (2 vols., 1877); King Lear of the “ Dolphin " under Captain Samuel Wallis on the latter's Like 11 (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 Lose 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 England). On the former occasion he explored a great part of basis, while in others he makes the text of the Cambridge (Globe) the south and east coasts of Tasmania, and made the earliest editors his foundation. His wife, Helen Kate Furness (1837British chart of the same. Most of his names here survive;
1883), compiled A Concordancclothe Poems of Shakespeare (1872). Cook, visiting this shore-line on his third voyage, confirmed the major portion of the county by Morecambe Bay. It is
FURNESS, a district of Lancashire, England, separated from Furneaux's account and delineation of it (with certain minor bounded S.E. by this inlet of the Irish Sea, S.W. by the sea, criticisms and emendations), and named after him the islands w. by the Duddon estuary and Cumberland, and N. and E. by in Banks Straits, opening into Bass's Straits, and the group now
Westmorland. Its area is about 250 sq. m. It forms the greater known as the Low Archipelago. After the" Adventure” was part of the North Lonsdale parliamentary division of Lancashire, finally separated from the “ Resolution” off New Zealand in and contains the parliamentary borough of Barrow-in-Furness. October 1773, Furneaux returned home alone, bringing with bim The surface is almost entirely hilly. The northern half is included Omai of Ulaietea. This first South Sea Islander seen in the in the celebrated Lake District, and contains such eminences British Isles returned to his home with Cook in 1776-1777. as the Old Man of Coniston and Wetherlam. Apart from the Furneaux was made a captain in 1775, and commanded the Duddon, which forms part of the western boundary, the principal "Syren” in the British attack of the 28th of June 1776 upon rivers are the Leven and Crake, flowing southward into a common Charleston, South Carolina. His successful efforts to introduce estuary in Morecambe Bay. The Leven drains Windermere domestic animals and potatoes into the South Sea Islands are worthy of note. He died at Swilly on the 19th of September District," however, tends to limit the name of Furness in common
and the Crake Coniston Lake. The usage of the term “ Lake 1781.
Sec Hawkesworth's Narrative of Wallis' Voyage; Captain Cook's thought to the district south of the Lakes, where several of the Narrative of his Second Voyage; also T. Furneaux's life by Rev. place-Dames are suffixed with that of the district, as Barrow-inHenry Furneaux in the Dictionary of Nolional Biography. Furness, Dalton-in-Furness, Broughton-in-Furness. Between