Page:Popular Science Monthly Volume 39.djvu/756

736 beneficent changes in material positively bad, and to so purify and purge it that it would inevitably produce steel phenomenally good, that wearied the minds, vexed the souls, and too often imparted a lurid hue and sulphurous flavor to the language of the early makers of cast steel. These nostrums represented every school of "medicine"; one prescribed heavy doses of certain "salts," another was loud in the praises of minute pellets of his most potential preparation; one of the advocates of the botanical treatment extolled the efficacy of a raw potato to "agitate the metal and cause it to throw off all its superfluities, while the "eclectics" roamed through all the fields of "physic" and claimed to appropriate all the virtues and ignore the vices of the other practitioners.

The original method of melting cast steel consisted in placing a single "pot" with its contents in a square vertical furnace, or "hole," whose top was level with the floor of the "casting house"; the furnace was then filled with either coke or anthracite coal, care being taken that the fuel was distributed equally on all sides of the "pot," which was provided with a "lid" to protect its contents from contamination by the entrance of coal or other matter.

The fire was then urged by the powerful draught of a chimney, or frequently by a "blower." Many of the later "melting holes," in which solid fuel was used, were made large enough to contain two, and some of them four "pots."

All the cast steel made in America prior to the year 1868 was melted by solid fuel in "holes" such as have been described; but in November, 1867, Messrs. Anderson and Woods, of Pittsburg, procured a license from the American owners of the Siemens patents for "regenerative gas furnaces," and under this license a "twenty-four pot" melting furnace was erected under the supervision of William Durfee, in their works at Pittsburg, Pa., in the spring of 1868, according to plans prepared by J. Thorpe Potts, C. E., who represented Dr. Siemens in America. This was the pioneer furnace in the United States using gaseous fuel for melting cast steel, and its success led to their rapid introduction in other works, so that to-day there are not many of the old-fashioned "holes" using solid fuel to be found.

In Fig. 51 we have a vertical cross section of a "Siemens regenerative gas furnace" for melting cast steel. Fig. 52 is a top view of the furnace, showing two of the "melting holes" covered and six "pots" in place in the open hole; the top of the furnace