.is a prefix a term indicating the mode of manu-facture. There could thus be no difficulty inunderstanding what is meant by pneumatic orBessemer steel, open - hearth or Siemens steel,crucible steel, blister steel, puddled steel. Ifit is necessary to distinguish the different qualitiesof each kind, the classification might very wellbe dependent upon the tensile strength of the ma-terial. Thus, steel which will bear a tensile strainof 25 to 30 tons per square inch might be called,as indeed it now is in common usage, “ soft”; from30 to 35 tons might be called “ mild ”; 35 to 40 tons,“hard;” 40 to 50 tons, “ extra hard”; leaving any-thing above this to be designated specially. Thiswill very nearly accord -with the classification pro-posed by Adolph Greiner, of Seraing , with theusage of Holley, and the recommendation of Hack-ney. The' classification arrived at by the Inter-national Commission at Philadelphia last year was avery good one ; but unfortunately makers and userswill not adopt it, and therefore it becomes almost adead letter. Our own Admiralty, the Board of Trade,and Lloyd’s, for instance, still persist in calling whatthe Commission would have designated as “ingot-iron,” either “Soft Bessemer or Siemens steel.”There is no difficulty in understanding what theymean by these terms, while there might be somedifficulty, as Siemens points out, in deciding whethera given plate would or would not harden, and there-fore whether it was “ingot-iron” or “ingot-steel.”
In this article the term steel will be used inits common and wider acceptation, and the variouskinds will be considered in their chronological order.
There is great probability that an alloy of ironthat would harden by sudden cooling, and thatcould be forged into edge tools, was discovered soonafter the isolation of the metal itself was effected.At all events, IIomer speaks of the art of temperingin such a way as to leave no doubt that in his timesuch an alloy was known. We have no record ofthe mode of production employed by the ancients,but it is feasible to suppose that it was by somemodification of the plan still adopted by the Hindoos—viz., by melting wrought iron in crucibles in con-tact with carbon. Hr. Percy considers that thisprocess of steel making is the most ancient, and hequotes from Dr. Buchanan’s description of the pro-cess as he saw it practised in 1807 as follows:—■
“A wedge of iron, forming about a third part ofone of the little lumps produced in an ordinary Hin-doo iron furnace, is put into a conical, unbaked claycrucible, of about the capacity of a pint, with theaddition of 3 rupees’ weight (531 grains) of the stemof Cassia auriculata, and two large green leaves of aspecies of Convolvulus or Ipomcea. The crucible thuscharged is closed at the mouth with a cap of unbakedclay well luted on, and then well dried near a fire.The furnace used is a little circular pit in the ground,somewhat dilated at the top. An earthen pipe, con-nected with two bellows, each consisting of abullock’s hide, and which are worked alternately,enters the fire-place at the bottom. A row ofcrucibles is first laid round the sloping mouth of the
-History. 851
fireplace; then within these another row is placed;and the centre of the arch thus formed is occupiedby a single crucible, making in all fifteen. Thecrucible in the outer row, opposite the nozzle of thebellows, is then taken out, and in its stead an emptycrucible is placed horizontally, with its mouth dir-ected inwards. This crucible can be readily drawnout and replaced, and the opening which it closesconstitutes the fire-hole through which fuel is intro-duced. The fuel is charcoal, with which the fire-place is filled, and the arch of crucibles, chargedas stated above, is covered over. The bellows arethen plied during four hours, when the operation iscompleted. A new arch of crucibles is constructed,and the process goes on night and day; five sets,of four crucibles each, being every day worked off.On breaking open the crucibles the steel is foundmelted into the well-known conical cakes of wootz,which usually present a radiated wrinkling on theirupper or flat surface, considered by Buchanan toindicate a tendency to crystallization. The cakes aresurrounded by some -vitrified matter.
Henry found a sample of wootz to contain—
Carbon, combined,. 1-333
“ uncombined. -312
Silicon,. -045
Sulphur. -181
Arsenic,. - 037
Iron, by difference,. 98-092
100 000
The following is an analysis of a sample of steelmade from Indian ore reduced by Blair’s process:—
Carbon, combined,. -400
“ graphite,. —
Silicon,. -090
Sulphur,. -081
Phosphorus,. -028
Manganese,. 1-200
Iron,. 98-500
100-299
It was very soft, but capable of taking an edge whenhardened.
In the sixteenth century a very curious methodwas employed for making steel. This was describedby several writers, among others by Vanoccio Biu-inguccio in 1540, and by Agricola in his “De ReMetallica, ” in 1560. This consisted in heatingmalleable iron in molten cast iron until the formerbecame pasty, by which time it had absorbed suf-ficient carbon from the cast iron to convert it intosteel. It was, in fact, a cementation process con-ducted at a very high temperature and with a fluidbath. The translation of the original, as given inDr. Percy’s work, is very curious, and well worthperusal.
Since steel occupies a medium position betweencast and wrought iron, it is natural to expect that inthe early stages of the manufacture of iron in fineryhearths, it would often happen that the workmenwould obtain a product more carburized than usual,and having, therefore, a steely nature. This was thecase; and the Styrian, Carinthian , Tyrolehe, Paal,and Siegen processes, which were largely practised