Page:Popular Science Monthly Volume 39.djvu/752

732 steel" was made directly from the ore or a suitable quality of "pig iron" was used. The operation, when ore was employed, consisted in removing the oxygen, and then by appropriate manipulation, together with a regulation of the blast and heat, the iron was combined with carbon derived from the fuel to such a degree as to convert the metal into a mass of crude steel; this was carefully drawn under a light, quick-working hammer into bars about an inch square; six or eight pieces of these bars were made into a "pile," welded together, and drawn into smaller bars. This process, called "refining" was repeated a number of times, and the quality of the resulting steel was designated by the terms "single" "double," or "triple refined," according to the number of weldings and hammerings. When "pig iron" was used, the operation consisted in so manipulating the metal and regulating blast and heat that a portion of the carbon in the "pig" remained in the resulting "bloom" of crude steel, which was subjected to the same "refining" as has just been described.

All the early attempts to make steel in America were in the "German manner"; but it was soon discovered that the ores and pig irons available were not of a proper quality, and attention was early directed toward the "cementation process," the details of which were fully described by Réaumur in 1722.

The operation of making "cemented" or "blister" steel consisted essentially in packing bars of wrought iron in charcoaldust in long boxes or "pots" made of sandstone or fire-brick. These "pots" were covered as nearly air-tight as possible and subjected to a high degree of heat (not, however, sufficient to melt the bars of iron), which was regulated as to temperature and duration according to the contemplated use to be made of the steel. As a rule, the higher the temperature and the longer time it was kept up, the greater the degree of carburization of the bars in the "pots" and the harder the resulting steel. When the iron is packed in the charcoal, one or more bars are allowed to project through openings in one end of the "pots"; these bars are removed at proper intervals of time, and from their appearance when cold the progress of the operation was judged. When the process of "cementation" was finished, the furnace was allowed to cool, and, as soon as men could work therein, the metal was removed from the "pots," and it was found that it had undergone a great change: instead of having a smooth surface, it was covered with a large number of "blisters" of varying size and thickness (hence the name "blister steel"), and, although when put into the "pot" the metal was very fibrous and tough, it was found