IRON. 



Jurnnee, called by fome a refinery, hut by others, to diftinguidi 

 -4t from one hereafter to be defcribed, a run-out furnace. It 

 confifts of a velTel open at the top, imbedded in Hone or 

 brick work, about two feet tliree inches long, two feet 

 ^vide, and ten inches deep. This is generally, in part, con- 

 llrudlcd of cad iron ; and, when fo made, has an outer cafe 

 about two or three inches diftant from the ii.ner one, which 

 is condantly fupplied with a dream of cold water to pre- 

 vent the apparatus from melting. The iron to be decar- 

 bonized is placed in this receptacle, and kept in a continual 

 ilate of fufion for three or four hours by the aid of a 

 coke fire, which is heaped to a confiderable height above 

 the level of the vefTel, and extended proportionally on the 

 hearth that furrounds it. The fize of the hearth is motlly 

 about three yards in length, and from two to three wide, 

 and is completely covered by ;he funnel of the overhanging 

 chimney. Bellows of confid^^rable lize are employed to carry 

 on the procefs ; and the current of air which iffues from 

 them is directed immediately on the furface of the iron by 

 one or more tuyeres. Thefe tuyeres arc double, like the 

 cafe, and continually cooled by the application of the 

 fame means. When the decarbonization is completed, the 

 metal is let out at an opening in the fid.. v.Iiich has been 

 kept clofe during the operation by a flopping of fand. It 

 flows into a groove about 18 inches wide, and fix or feven 

 feet long, conftrufted of ftone in the floor that furrounds 

 the furnace. The bottom of the veffel is fo placed as to 

 be nearly on a level with the floor ; the only elevation given 

 to it being what is merely fufficicnt to let the iron run 

 out with facility. A confiderable quantity of vitreous oxyd 

 is formed during the procefs ; and the lofs in the weight 

 of metal, which is Hated to amount to from ^tli to ith, is 

 principally referable to this circumftance. The total quantity 

 of carbon which the iron contains originally is not elli- 

 iriated at more than ^'5 th ; and yet the approach of it to 

 the pure date, or, in technical language, to the date of 

 bar or wrought Iron, after this operation, is very inconfi- 

 derabie. 



The cake of metal procured by thefe means is broken 

 into lumps of a convenient fize, and fubjeded, in a furnace 

 of another defcription, to a procefs known in the art by 

 the name oi puddling . The furnace, which is alfo didinguidicd 

 by the fame term, is a variety of tlie reverberatory ; and at 

 the immediate point where the flame firikes upon the 

 hearth, a fliallow concavity is worked out, in which the 

 melted iron is expofed. Oppofite to it is a door, and through 

 this the metal is kept in continual agitation, by means of a 

 fort of rake, for the purpofe of exhibiting frefli furfaces 

 perpetually to the influence of the air. Water is likewife 

 occafionally throvi'U in, which in fome degree contributes 

 to the decarbonization. With the lofs of carbon, the iron 

 alfo lofes its fufibility, and about the middle ftage of the 

 operation appears in the form of fmall detached lumps, 

 which fcarcely feem to exert any affinity for each other. 

 At length, however, by much llirring, and frequently prefiing 

 them together, they cohere into a pulpy niafs ; and being 

 gathered into pieces of a convenient fize, are carried under 

 rollers, where, after pafTuig through four pairs, in fucceffion, 

 of a gradually diminifliing guage, they are produced into 

 plates feven or eight inches wide, and three feet or more 

 ja length. Confiderable quantities of matter are fqueezed 

 out in the rolling, which principally coulid of a vitreous 

 kind of oxyd. This is, for the mod part, to be referred 

 to the adlion carried on in the furnace ; but fome portion of 

 it is, in all probability, created by the combudion of fmall 

 pieces of fluid metal, which, engaged amongft the particles 

 «f the puddled mafs, are hurled through the air in a date 



of vivid inflammation, by the comprellive viol,"i)ce of the 

 rollers. The total lofs thus fudained is edimated at from 

 ±l\\ to |th. The plates obtained by this treatment have a 

 very incompact appearance ; and if attempted to be worked 

 in the date they are then prefentcd under, would crumble 

 almoll wholly into fmall granulated lumps. To impart to 

 them the necedary clofenei's and folidity, they are again. 

 heated in another kind of furnace, asd beaten forcibly with 

 a heavy hammer, which is raifed by machinery. 



Previoufly to being thus treated, they are broken up into 

 cakes of fmall fize, and placed upon circular fiabs of done 

 from 8 to 12 inches in diameter. The fize of the cakes is 

 in a great meafure determined by a particular efiert of the 

 lad pair of rollers that they are paflcd throtigh : ribs, of a 

 diamond fliape, girding either one or both of them, on the 

 whole extent of their furface, which leave a deep indenta- 

 tion on the plates, fo as to render them eafily frangible in 

 that direftion. The height to which thefe cakes are piled 

 on the cirCTilar flab juil fpoken of, is generally about 12 

 inches ; and when lo prepared, they are placed on the hearth 

 of a reverberatory furnace, which differs but little in form 

 from that employed for puddling, except in being flat at the 

 bottom indead of concave. The furnace is denominated a 

 hailing furnace ; and the piles of metal, pies or halls. They 

 are continued in this fituation until they have arrived at 3 

 welding heat, and are then removed by large tongs under 

 the droke of the hammer. Near to the place a fmith's 

 forge is kept in blad, where long bars of iron are alfo urged 

 to tlie welding point ; and, after the firft droke or two of. 

 the hammer, united to the lalied mafies, to afford greater 

 convenience in turning them. The mafies are beaten out 

 into ingots of about three feet in length ; and the bar lad 

 mentioned being fepai-ated, they are divided deeply by 

 an inftrument termed a fet, to facilitate their being after- 

 wards broken ; and the procefs is then completed. They 

 are in this ftate called blooms, and have yet to under- 

 go another operation, for the purpofe of being madji 

 into bars or plates. Much lofs is fudained by the lad 

 treatment, and principally from the fame formation of oxyd 

 as was noticed in the preceding cafe. The quantity thus 

 lod, added to the wade occafioned in the blocmcry, which 

 comes next to be defcribed, is ufually confidered as equal 

 to \X.\\ of the metal obtained by puddling; which v.'ill make 

 the total deficiency, by all the operations, as nearly equi- 

 valent to \^. The ingots or blooms, which are received 

 from the hammer, after being broken, over a fmall wedge- 

 fliaped block of iron called a tup, are placed in a fpecies 

 of reverberatory, very fimilar to the balling furnace, and 

 denominated a blooming furnace, or hloomery. They are 

 here heated to welding, and then fubmitted to the requifite 

 predure under rollers, which are cither plain or grooved, 

 according as the iron is wiflied to be obtained in plates or in 

 bars. This completes the whole of the procefles neceffary 

 for making the bed malleable iron ; and it refults from the 

 obfervations which have been premifed, that, in order to pro- 

 cure one ton of it, five-and-thirty hundred weight o{ forge- 

 pig is previoufly required. 



Two other modes of operating are at prefent in ufc ; one 

 of which omits the puddling, and the other, that part of the 

 foregoing procefs that concerns the fabrication fef blooms. 

 In the former, iron is expofed to the heat of a charcoal fire, 

 in a fpecies of furnace prccifely fimilar to the one before de- 

 fcribed as a refinery, or run-out furnace ; and is continued in 

 that fituation, until the metal is thouj^ht to be fufficicntly 

 decarbonized. It is very frequently dirred during the 

 operation ; and when brought into nature, (to ufe the tech- 

 uical expreffion,) is colleftcd into mafies^ and removed by 



tongs 



