FURNEAUX 



3379 



FURNESS 



improvements, 

 and in 1882 was 

 able to melt 10 Ib. 

 of platinum in a 

 furnace which 

 consisted of a 

 carbon crucible 

 constituting one 

 pole of the system, 

 and a vertical car- 

 bon rod suspended 

 in it forming the 

 other. 



Electric fur- 

 naces may be 

 grouped roughly 

 under three main 

 heads : (1) those 

 in which the heat 

 is derived from an 

 electric arc; (2) 

 those in which the 

 substance to be 

 heated acts as a 

 resistance or is 

 in contact with 

 a resisting substance ; 



Furnace. Sectional elevation of Heroult Arc furnace. 

 A, furnace; a, steel plate casing, BB', electrodes; C, flexible 

 cable connexion between electrodes and current trans- 

 former ; D, electric motor and supplementary hand gear 

 for adjusting positions of electrodes in the furnace ; E E', 

 racks for tilting furnace ; F, hydraulic pusher for tilting 

 furnace to discharge molten contents. Position when 

 pouring molten metal is indicated by the broken lines 



(3) those 



which use arc and resistance heat 

 in combination. 



The first class is exemplified by 

 the Moissan furnace and the Stas- 

 sano iron-smelting furnace, with an 

 arc formed inside a covered cham- 

 ber of refractory material above 

 the substance treated, which re- 

 ceives the heat directly by radia- 

 tion and by conduction from the 

 walls of the chamber. 



The Heroult Furnace 



The second or resistance furnace 

 is exemplified by the Heroult type 

 of steel furnace, which consists 

 essentially of a "hollow bed of re- 

 fractory material on which the 

 charge to be melted is placed and 

 one or more carbon poles placed 

 vertically above it and provided 

 with means by which they may be 

 lowered down to the material on 

 the hearth. The heating is de- 

 veloped by numerous small arcs 

 formed between the poles and the 

 charge, which may be steel scrap 

 or pig iron. As these arcs flash 

 about from point to point of the 

 charge the melting gradually pro- 

 ceeds until the charge is entirely 

 molten. In this type of furnace 

 the anode is formed by adjustable 

 carbon rods, and the cathode is 

 the hearth itself and its containing 

 casing. (See Aluminium, illus.) 



The resistance offered to the 

 passage of the current through the 

 mass of material on the bed of the 

 furnace suffices to melt the charge, 

 but does not decompose it. The 

 decomposition is accomplished by 

 the electrolytic action of the cur- 

 rent, which breaks up the ore, 

 setting free oxygen which combines 

 with the carbon of the anode and 

 escapes as carbonic oxide, which 

 bums as it issues from the furnace. 



The induction furnace is based 

 upon a different principle. In the 

 Kjellin iron-smelting furnace alter- 

 nating high-tension current, passed 

 through a vertical coil with heavy 

 iron core, induces 

 a low-tension cur- < 

 rent in a charge of \ 

 ore or metal which 1 

 occupies an annu- \ 

 lar trough concen- \ 

 trie with the coil . 4 

 and acts as the 

 secondary circuit. 



Indirect resist- 

 ance heating is 

 used in the manu- 

 facture of carbor- 

 undum (carbide of 

 silicon). A core of 

 small lump coke is 

 the resistance. Round it is packed 

 a charge of mixed carbon powder, 

 sand, sawdust, and salt, covered 

 with a coating of loosely piled 

 bricks. The intense heat of the 

 core, which is converted into pure 

 graphite, causes the carbon sur- 

 rounding it to combine with the 

 silicon of the sand as carborundum 

 to a depth of a foot or more. 

 The body of the kiln is broken up, 

 and the partly combined material 

 used for the next charge. 



At the end of 1918 there were in 

 Great Britain about 140 electric 

 furnaces in operation or under 

 erection, much the greater number 

 being of iron or steel. In the 

 U.S.A. there were about 287, 

 and in Canada 43. The great 

 advantage of the furnace, apart 

 from the facility with which very 

 high temperatures may be reached, 

 lies in the greater purity of the 

 products turned out, due partly 

 to the absence of contact between 

 the metal and deleterious elements 



in ordinary solid or gaseous fuel, 

 and partly to the more regular and 

 higher temperatures which may be 

 employed. Whether the use of the 

 electric furnace for the direct pro- 

 duction of pig iron will much 

 extend and the blast furnace be 

 ultimately superseded, it is too 

 early to predict. Progress in this 

 direction will be determined by the 

 relative costs of coke and the 

 equivalent in electrical energy. 

 Where water-power is abundant 

 and cheap, and other conditions 

 are favourable, there is no doubt 

 that the electrical system will be 

 favoured. See Aluminium ; Cop- 

 per ; Iron : Steel ; Welding, Electric. 



Furneaux. Group of islands 

 between Tasmania and Australia 

 in Bass Strait. They were dis- 

 covered in 1773 by the English 

 navigator Tobias Furneaux. Flin- 

 ders Island, the largest, is 35 m. 

 long and 10 m. broad. Pop. 170. 



Furnes. Town of Belgium, in 

 the prov. of W. Flanders. It is 

 16 m. E. of Dunkirk, on the rly. 

 from Dunkirk to Dixmude. In 

 the Great War it was first bom- 

 barded bv the Germans, Oct. 24- 



The Grand' Place, with the Hotel de Vffle, 

 Palais de Justice, and Church of S. Walburge 



27, 1914, in which month the 

 Allies evacuated it. The French 

 conferred the croix de guerre on it 

 in 1920. Pop. about 6,000. 



Furness. District in the N.W. 

 of Lancashire, England. It is de- 

 tached from the main portion of 

 the county by Morecambe Bay. 

 Its area is 250 sq. m. The hematite 

 iron ore in the S. of the district 

 was worked by the Romans. 



Furness, CHRISTOPHER FURNESS, 

 IST BARON (1852-1912). British 

 shipowner. Born April 23, 1852, 

 at West Har- 

 tlepool, he was 

 educated pri- 

 vately, and in 

 1876 became a 

 shipbroker, es- 

 tablishing soon 

 afterwards the 

 Furness line of 

 steamers. In 

 1885 he went 

 into partner- 

 shipjjwith 



1st Baron Furness, 

 British shipowner 



