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Page:Popular Science Monthly Volume 38.djvu/180

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168
THE POPULAR SCIENCE MONTHLY.

ing to Swedenborg) especially adapted to the working of bog-ores, large quantities of which were actually smelted in New England, it does not seem at all improbable that furnaces of similar form may have been used there for smelting such ores; and the fact that this furnace produced wrought iron in masses of considerable weight would make it of especial utility in connection with forges, which were quite numerous in the New England colonies at the beginning of the eighteenth century.

The Stücköfen was an enlargement upward of the Osmund furnace, and may be pretty accurately described, as one Osmund furnace inverted upon another, its interior form being that of two cones united at their bases, a hearth similar to that of an Osmund furnace being formed at the lower part. We have no certain information that the Stücköfen was ever used in this country; but as this furnace was well known in Europe, where it had been in use for several centuries, those interested in the earlier smelting enterprises in the American colonies must have been acquainted with its construction, and it is very probable that some of the earlier blast-furnaces were Stücköfens under another name. The fact that this furnace could be so worked as to produce either cast or wrought iron, as desired, would make it especially valuable in a new country, where there was not sufficient demand for either metal to keep a furnace constantly employed. Besides those already enumerated, there was another method of producing a "bloom" of forgeable iron; viz., by the remelting of "sowe" or "pig" iron in a "Catalan forge" or "blomary fire." In colonial times this operation was largely used and was often described as "refining," and the premises in which it was carried on were frequently called a "refinery"; but the reader must not conf ound this term with that applied to a comparatively modern apparatus of quite different construction and purpose, which we will describe later.

This old refining process[1] consisted substantially of melting the pig iron with charcoal, and then directing the blast upon the melted iron—which was stirred occasionally by proper iron tools—until its impurities in a great degree were expelled, and a spongy mass of forgeable iron was formed (quite similar, in fact, to that obtained when ore alone was used), which could be hammered into a "bloom."

Thus far we have confined ourselves mainly to a description of methods and apparatus for the production of "sowe" or "pig" iron and "blooms," which were either in actual use in America


  1. This process is even now worked to a limited extent, but its use is steadily declining. Mr. Swank reports that "the production of blooms and billets from pig and scrap iron in 1889 was 23,853 net tons, against 25,787 tons in 1888, and 28,218 tons in 1887."