STEEL.— Bessemer Process. 861

Railway Steel and Plant Co. The latter gentlemanread a very interesting and able paper on “ BessemerSteel ” before the Association of employers, foremen,and draughtsmen of the mechanical trades of GreatBritain , in 1868; and in this paper he makes thefollowing statement:—

“It was usually the custom to melt the pig metalused for conversion into Bessemer steel in air orreverberatory furnaces. Now this is a costly andwasteful way of melting iron for this purpose.There is an opinion prevalent amongst engineersgenerally, that by the melting of pig iron in airfurnaces it is improved thereby. For foundry pur-poses it undoubtedly is, but for our use it is not;it is very much deteriorated. The air furnace, asyou are all aware, is purely an oxidising furnace;that is, the metal, after it is melted, is subjected toa current of heated air passing over it continually,and, as a matter of course, is continually beingoxidised from the moment of its first melting untilit is tapped out; it is consequently much wasted,and the yield of steel is therefore proportionablyless. In case of accidents in the after part of theprocess, such as a disabled vessel or any disarrange-ment in the pit, the waste of metal is still going onin the furnace. I have seen cases of this sort wherenot more than 50 per cent, of the iron has been gotout at tapping, and what has been got out wasutterly useless for conversion. But the loss of ironis not the greatest evil in this case. You will re-member I told you that it is requisite that the metalused for this process should contain graphitic orfree carbon; now, the action of the air furnace notonly oxidises the iron, but it also burns off the carbon,the very fuel required for the conversion of the castmetal into steel. To put it in other words, it refinesit too much, and takes cut what we require to raisethe temperature of the metal to such a pitch as tokeep it fluid when in the state of pure iron ; ofcourse this deterioration is only in proportion to thetime it is exposed to this oxidising influence, butunder the most favourable circumstances there isalways a deterioration. Early in the year 1865I suggested to the directors and manager of theRailway Steel and Plant Co., Newton Heath, thefeasibility of melting our metal in a common cupola;it met with much opposition, and, I assure you,some very learned arguments were used against itby outsiders; and some people who ought to haveknown better, said that if we began we should neverhave a good heat. This was at the commencementof our operations at Newton Heath, and thoughthoroughly convinced of the practicability of the thing,

I rather chose to get our materials into the marketby the old method of melting, than meet at once thedirect opposition which the novelty had excited in acommercial way. By the permission of the managingdirectors, I had 3 tons melted in our foundry cupola,brought liquid in a ladle, and poured into the con-vertor, made the heat in the usual way, hammeredit into blooms, broke one or two of them; when thegentlemen above referred to, who had expressed theirbelief that we should not get one good heat, saw

them (without knowing that they had been made bythe use of the cupola), they said they were the finestsamples they ever saw. The matter was very soonsettled; we erected two cupolas on Woodward’ssteam jet principle, and we have not used the airfurnace since. The Mersey Iron and Steel Co. werethe next to adopt it, and now it is in general useboth at Sheffield and elsewhere. The cupola pos-sesses many advantages over the air furnace; thefirst cost is not near so great, and the maintenancefor the number of tons of iron melted is consider-ably less; the cost of melting is greatly reduced inthe article of fuel, and there is little or no waste ofiron in remelting. But the greatest thing in itsfavour is the ease with which we are enabled toremelt all steel scrap cuttings and chippings ofevery kind. It is the complete cure for the scrapdifficulty, which has for so long a time been a greatdrawback to this process. It is next to impossibleto remelt Bessemer scrap in the air furnace, onaccount of its oxidising action, and the small amountof carbon which the scrap contains; while in thecupola we have not the least difficulty, because ofthe reducing * action of the furnace, and thematerial being surrounded with carbonaceous matterin a high state of combustion.”

Repeated experiments by Snelus and othershave shown that good grey iron can be remeltedin a cupola with good coke if a small portionof limestone be added to the charge, without riskof taking up sulphur. It has also been thoroughlydemonstrated that during this process of remelt-ing some silicon — generally from one quarterto one half per cent.—is removed from the iron;and it is the opinion of Snelus that the improve-ment in tenacity which Fairbairn found as aresult of several times remelting the same greypig iron was due to this removal of silicon. On theother hand, white iron, or iron poor in carbon andfree from manganese, does certainly take up sulphuron remelting it in a cupola. There is always a smalltrace of phosphorus present in coke, and doubt-less this is mostly taken up by the iron duringremelting; so that by performing the operation agreat number of times, as Fairbairn did, there isa point reached at which the iron begins to deterio-rate. And this was exactly what he found by hismechanical tests. But the chemical analyses ofsome of these samples, which were made by Calvert,do not appear to support these conclusions. Theanalytical results, however, as will be seen from anexamination of the figures given below, are soremarkable that it is evident that they are not re-liable, and it is desirable that they should be repeated.

The pig was No. 3 Eglinton, hot blast, remeltedin a cupola with coke. Three test pieces, 1 inchsquare and 5 feet long, were taken with each cast,and they were broken on supports, 4 feet 6 inchesapart, by a centre load. The experiment was con-tinued up to the eighteenth remelting, and samplesfrom the first, eighth, tenth, and eighteenth re-melting were analysed by Calvert.

* The reducing action in a cupola is very slight.—En.