AMERICAN INDUSTRIES SINCE COLUMBUS. 741 



much of it for remelting in pots, and a great deal being used 

 for forgings. In the " Centennial Exhibition of 1876 " there was 

 shown in the Swedish department by the " Motala Iron and Steel 

 Works" a number of welded coils of "puddled steel" intended 

 for " gun-hoops " and several finished " hoops." 



The introduction of the " Bessemer process " into the United 

 States preceded by a few years that of the " open-hearth," but 

 their advent was practically coincident. For convenience, the lat- 

 ter will be described first. By this process pig iron of a suitable 

 quality is melted on the hearth of a reverberatory furnace, and then 

 either wrought-iron " scrap " or iron ore is mixed therewith. 



The principle of the " open-hearth " process was well understood 

 by metallurgists for many years before it could be carried into prac- 

 tice, owing to the impossibility of securing a sufficiently intense and 

 continuous heat in any ordinary form of reverberatory furnace. 

 As early as 1824, M. Bre'ant* stated that "it would be possible 

 to produce cast steel on a very large scale in reverberatory furnaces 

 by following a process analogous to that of the depuration of bell- 

 metal that is to say, by adding to the metal in fusion [pig iron] 

 a portion of the same metal oxidized, or, still better, natural oxide 

 of iron." In 1845 Josiah Marshal Heath (who invented the use 

 of manganese in melting steel in pots) patented a method of mak- 

 ing steel in large quantities by melting cast and wrought iron to- 

 gether upon the open hearth of a reverberatory furnace ; and, for 

 the purpose of preventing the contamination of the metal by the 

 ashes of solid fuel, he designed to heat his furnace by jets of gas. 

 But the experiments of Heath, although pointing out clearly the 

 road to success, were not themselves successful. M. Alfred Sudre 

 patented in England, December 31, 1858, a method of melting 

 steel in a reverberatory furnace. He made experiments in 18G0 

 and 1861 near Paris, the expense of which was defrayed by 

 the Emperor of the French, but they fell short of a commercial 

 success. It was not until 1864 forty years after the original sug- 

 gestion of M. Bre'ant that the making of steel by the fusion of 

 pig iron and wrought-iron " scrap " on the open hearth of a gas- 

 fired reverberatory furnace could be regarded as commercially 

 and technically successful. This result was attained by a com- 

 bination of the " regenerative gas furnace," then recently invent- 

 ed, with the perseverance and technical skill of Messrs. Emile and 

 Pierre Martin, who, notwithstanding its failure in other places, 

 erected one of the Siemens furnaces in their works at Sireuil, 

 France. Evidently there was a lurking doubt in the minds of 

 the Messrs. Martin, for this furnace seems to have been so con- 

 structed that, if it failed as a melting, it would succeed as a heat- 



*Annales de Minos, 1824. 



