STEEL.— Bessemer Process.

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the time of Heath. In 1839, however, JosiahMarshall Heath took out a patent for the additionof manganese to steel in the crucible in the form of“ carburet of manganese,” which he made by sub-mitting black oxide of manganese and carbonaceousmatter to a very high temperature. This materialwas for some time sold as Heath’s powder; but liehimself afterwards showed his agent that it was notnecessary to form the carburet by a separate operation,and that the same result would be attained by simplyputting the mixture of oxide of manganese andcarbon into the crucible with the steel. Advantagewas taken of this deviation from the wording of thepatent to ignore its legality, and one of the mostremarkable patent trials on record was the result.The story is pathetically told by Charles Dickens in Household Words, to which the reader is re-ferred. The discovery made by Heath of the powerpossessed by manganese to produce good steel outof moderately inferior iron led to a largely increasedmanufacture; and his plan is still followed very exten-sively, although his oxide of manganese and carbonare now giving place to R. Mushet’s spiegeleisen andferro-manganese. Since the invention of the re-generative system by Dr. Siemens, his plan of gasfurnaces has largely superseded the old coke firesfor crucible steel melting. Plate I. shows a verticalsection of a Siemens crucible furnace of the mostrecent kind, as erected by Murdock, at the SteelCasting Works, Barrow. Whereas the old cokefurnaces used 2£ to 3 tons of coke to melt 1 tonof steel, not more than Itt ton of coal is requiredfor the same work in the Siemens producer.

The Bessemer Process. —No metallurgical dis-covery has been more pregnant with benefit to theworld in general, or more profitable to its author,than the invention which is now universally knownas the Bessemer process. Although it is little more thantwenty-two years since Bessemer first made histiny experiment with about 25 lbs. of metal in asmall crucible, and less than twenty years since heexplained to the Institute of Civil Engineers hiscomplete plans for working the process on a com-mercial scale, so rapid has been the growth of themanufacture that it is estimated that in the year1877 over two million tons of steel were actuallymade by the Bessemer process. Estimating this atonly £5 per ton in the ingot, we have the enormoussum of £10,000,000 sterling as the value of the rawsteel produced by this process in one year—theactual value of the finished articles being aboutdouble this amount. Or to put the matter inanother light: there are at the present time closeon 350 Bessemer convertors in existence. Assum-ing the plant in connection with and dependentupon each of these to have cost on an average£20,000 (which is a moderate estimate), we findthat something like £7,000,000 sterling have beeninvested in works for carrying on the Bessemerprocess and finishing the articles produced from it,while there are probably no less than a quarterof a million workpeople engaged in the variousbranches of the manufacture.

Bessemer’s first experiments were made on asmall scale at his Bronze Manufactory in London ,where, in order to test his ideas regarding therefining of iron by blowing air through it, he had asmall crucible furnace constructed; and after melt-ing about 25 lbs. of pig iron in a crucible, he passed aclay pipe into the metal, and forced a current ofair through it for some time. The result was thathe blew out or wasted about half his material; butthe remaining half proved to him conclusively that ifair was blown upward through molten iron insteadof merely on to its surface, as in the old Welshrefinery, much greater refining action was pro-duced. His aim was to produce, if possible, animproved metal for guns. Having satisfied himselfthus far, he took out his first patent, dated October17, 1855:—“ Improvements in the manufacture ofcast steel,” in which he proposed to use cruciblesplaced in a rectangular furnace, with the fire barsat the side instead of at the bottom. Each cruciblewas to have a tap hole in the bottom, through whichthe metal was to be tapped into a mould beneath atthe proper time. Steam or air, or both, were to beforced through a pipe to the bottom of the pig iron,which was to be run into the hot crucible in a fluidstate. The invention was tersely described as con-sisting in “ forcing currents of air or of steam, orof air and steam, into and among the particles ofmolten crude iron, or of remelted pig or refinediron, until the metal so treated is thereby renderedmalleable, and has acquired other properties commonto cast steel, and still retaining the fluid state ofsuch metal, and pouring or running the same intosuitable moulds.” The inventor distinctly statesthat “ steam cools the metals, but air causes a rapidincrease in its temperature, causing it to pass froma red to an intense white heat.”

On December 17 of the same year, Bessemerobtained a further patent for blowing the air upthrough the molten iron, which was to be containedin a spherical or egg-shaped vessel of iron, lined withfire-brick, and suspended upon axes; and when the pro-cess had been carried far enough, the metal wasto be poured from the vessel into moulds. Thisarrangement is cleai-ly the first germ of the idea oftipping the vessel on axes to discharge the fluidiron, instead of tapping it through a hole in thebottom of the crucible; but in this apparatus thesingle blow-pipe carrying the air downwards to itsescape orifice was still retained. Later on, however(May, 1856), we find Bessemer patenting an uprightfixed cylindrical vessel, with several twyer-pipespermanently fixed into, and forming part of thelower lining of the vessel. This form of converting-vessel has been extensively adopted in Sweden forworking small charges of metal; but it has beenfound in practice on larger quantities of metal, thatthe operation of opening the tapping-hole was oneof great difficulty and delay, and not unfrequentlycaused a charge to be over-blown and spoiled;because the blast was necessarily continued so longas the metal was retained in the vessel. In thisarrangement the blowing operation was also neces-