8 14 THE POPULAR SCIENCE MONTHLY. 



been passed through the other regenerator, it burns, giving out in- 

 tense heat. 



There are two methods now in use for the production of steel in 

 the reverberatory furnace, or open-hearth, as it is called. In France, 

 pig-iron and scrap-steel are fused together ; in England, pig-iron is de- 

 carburized by means of iron-ore, some scrajD, however, being generally 

 added for the sake of utilizing it. As in the Bessemer process, the 

 necessary amount of carbon is imparted to the metal by the means of 

 spiegeleisen or ferro-manganese. This process has been largely em- 

 ployed for the production of ship and boiler plates. It has the great 

 advantage that the metal can be kept fluid on the hearth, and its com- 

 j)Osition adjusted until it is exactly that required. 



In 1876 a patent w^as taken out by M. Pernot, in which it was 

 proposed to produce steel on an open-hearth furnace with a revolving 

 bed, inclined at an angle of 5 or 6 to the vertical. Pig-iron previ- 

 ously heated to redness is placed in the bed of the furnace and covered 

 with scrap-steel. The bed of the furnace is then made to revolve 

 slowly, the pig gradually melts, and the scrap is alternately exposed 

 to the strong heat of the flame, and then dipped under the molten pig- 

 iron. In this way the fusion is very rapid, comparatively, the whole 

 mass becoming fluid in about two hours. The process is then com- 

 pleted in the ordinary way. M. Pernot informs me that he has just 

 taken out a patent for an arrangement of his furnace by means of 

 which he can employ gas under pressure, and that within the last few 

 months he has obtained by this means results which have never been 

 equaled before. 



The Ponsard furnace aims at combinino^ the advantao^es of the 

 Bessemer and open-hearth processes. The furnace is so arranged that, 

 by giving it a half-revolution on its oblique axis, the tuyeres with 

 which it is supplied may be brought either beneath or above the sur- 

 face of the bath of metal. By these means the metal can be rapidly 

 decarburized nearly entirely, as in the Bessemer converter, and then, 

 by removing the tuyeres from beneath the metal, the final adjustment 

 of the carbon can be made as in the Siemens process. The rapid de- 

 struction of the tuyeres which is effected is a formidable obstacle to 

 the practical success of this process. 



The one important drawback to the Bessemer process was that 

 phosphorus was not in any degree eliminated by it. Notwithstanding 

 this, enormous quantities of steel were made by it ; and, within the 

 last three years, means have been devised in the Thomas-Gilchrist, or 

 " basic " process, by which this difficulty has been overcome. In the 

 ordinary Bessemer converter the lining was formed of ganister, a 

 siliceous material, the chemical effect of which was to prevent the 

 elimination of phosphoric acid. Messrs. Thomas and Gilchrist sought 

 a basic material which they could substitute for the ganister, and 

 found a magnesian limestone which worked very satisfactorily. The 



