IRON 941 



This outlet being closed, and the furnace filled with charcoal, fire is kindled at the 

 bottom. Whenever the whole is in combustion, the roasted ore is introduced at the 

 top in alternate charges with charcoal, till the proper quantity has been introduced. 

 The ore falls down ; and whenever it comes opposite to the tuyere the slag begins to 

 flow, and the iron drops down and collects at the bottom of the hearth into the mass or 

 Stuck ; and in proportion as this mass increases, the floss-hole for the slag and the tuyere 

 is raised higher. When the quantity of iron accumulated in the hearth is judged to 

 be sufficient, the bellows are stopped, the scoriae are raked off, the little brick wall is 

 taken down, and the mass of iron is removed by rakes and tongs. This mass is then 

 flattened under the hammer into a cake from 3 to 4 inches thick, and is cut into two 

 lumps, which are submitted to a new operation ; where it is treated in a peculiar 

 refinery, lined with charcoal brasque, and exposed to a nearly horizontal blast. The 

 above mass seized in the jaws of powerful tongs, is heated before the tuyere ; a por- 

 tion of the metal flows down to the bottom of the hearth, loses its carbon in a bath 

 of rich slags or fused oxides, and forms thereby a mass of iron thoroughly refined. 

 The portion that remains in the tongs furnishes steel, which is drawn out into bars. 



This process is employed in Carniola for smelting a granular oxide of iron. The 

 mass or Stuck amounts to from 15 to 20 hundred-weight after each operation of 24 

 hours. Eight strong men are required to lift it out, and to carry it under a large hammer, 

 where it is cut into pieces of about 1 cwt. each. These are afterwards refined, aud 

 drawn into bars as above described. These furnaces are now almost generally aban- 

 doned on the Continent, in favour of charcoal high or blast-furnaces. 



Chenofs Process. As far back as 1823, M. Adrien Chenot introduced a process for 

 preparing metallic iron, in a spongy form, direct from the ore by cementation in 

 charcoal. The ore usually employed in this process is brown haematite, which, in the 

 form of lumps, is mixed with wood-charcoal in more than sufficient quantity to effect 

 its deoxidation. The furnace used for reduction consists of a cubic pedestal of masonry, 

 surmounted by a truncated cone, and containing two rectangular chambers or retorts, 

 which widen in the lower part to facilitate the descent of the reduced charge. Each 

 retort is surrounded by a series of vertical flues, communicating below with the fire- 

 places and above with a large flue. The reduced iron is discharged from the retorts 

 on to a special cooler, where oxidation is prevented. The daily charge of a furnace, 

 working with a single retort, at Hautmont, consisted of about 1 ton of calcined 

 Sommorostro ore (containing 55 per cent, of iron), and about \ ton of wood-charcoal. 

 This charge would yield about 12 cwts. of iron-sponge, and about 2 cwts. of charcoal 

 would be regained as the excess over the quantity needed for reduction. At the same 

 time there is about 1 ton 6 cwts. of coal consumed as fuel. The reduction occupies 

 three days, but as the freshly-formed sponge is allowed to remain three days in the 

 cooler, the entire process occupies six days. When perfectly reduced, the iron sponge 

 presents a bright grey colour, and is so soft that it may be readily sliced with a knife ; 

 it is easily ignited, and when set on fire burns until it is completely oxidised. The 

 specific gravity is very variable, but the average is about T25. 



In addition to the ' external ' or ' indirect ' method described above, Chenot's sponge 

 may be obtained by an ' internal ' or direct ' method, in which the ore is reduced not 

 by means of solid charcoal, but by a hot current of carbonic-oxide gas. The furnace in 

 which this reduction is effected is similar to that used for the indirect process, excepting 

 that the reducing chamber is connected with gas-furnaces for generating the carbonic 

 oxide. A modification of Chenot's direct method, by M. Tourangin, has been used both 

 in France, and near Bilbao, in Spain. The iron-sponges are balled up in a charcoal 

 hearth. It should be remarked, that the raw material suited for Chenot's process 

 should be a pure ore, such as haematite or spathose ore, porous in texture, and not 

 fusible at the temperature at which the reduction is effected. 



Gurlt' s Process. In 1857, Dr. Adolph Gurlt introduced a process for reducing iron- 

 ores by means of gaseous fuel, maintaining that either cast-iron steel, or wrought-iron 

 could be obtained according to the proportion of carbon in the reducing gases. 

 It was said that the process effected a saving of about 50 per cent, of fuel, 

 compared with that consumed in the blast-furnace. The reduction and cementation 

 of the ore requires a current of reducing gases, which may be generated at a moderate 

 temperature ; but the fusion of the reduced iron must be effected at a higher tempera- 

 ture in a current of neutral gas, that is to say, neither reducing nor oxidising. Hence 

 the process was resolved into two operations conducted in separate furnaces. The re- 

 duction was effected in a furnace with a shaft similar to that of an ordinary blast- 

 furnace, and supplied with carbonic oxide from a gas-generator. The fusion was 

 conducted in a closed hearth, connected with two gas -generators, and supplied with a 

 blast through tuyeres. Experiments made by Gurlt, in 1857, at the Eheinbach Hiitte, 

 near Bonn, decidedly failed, but the process was afterwards successfully worked, in a 

 modified form, at Santa Ana de Bolueta, in Biscay. The ore used at Bolueta was 



