8i2 ' THE POPULAR SCIENCE MONTHLY, 



process had been a long time in use, however, before it occurred to 

 any one to fuse the steel and make it homogeneous. This was done by 

 Huntsman, about 1760. 



By all the processes we have so far reviewed, good steel could be 

 produced, but only in small quantity and at great expense. The ap- 

 plications of steel were, in consequence, very limited ; in fact, prac- 

 tically, its use was confined to implements with a cutting edge. 



In 1845 Heath patented a process which, had it been successful, 

 would have given him the power of producing steel in quantity. He 

 proposed to melt scrap-iron in a bath of molten pig iron in a reverber- 

 atory furnace heated by jets of gas. There w^ere two conditions 

 wanting in this method, which caused it to be a failure, viz., a suffi- 

 ciently high temperature, and the power easily to regulate the charac- 

 ter of the gases employed. Nevertheless, in this suggestion is to be 

 found the germ of one of the two most important processes of the 

 present day. 



The dominant idea in treating cast-iron for steel had always been 

 to refine the metal by the action of atmospheric air, and this was 

 effected by causing a current of air to impinge upon the surface of 

 the metal, by means either of a blowing apparatus or the drawing 

 action of a chimney-stack. What more natural than that it should 

 occur to some one to refine iron by blowing air into it, instead of 

 merely on to its surface ? We find that this idea did occur to several 

 persons, widely separated, in the year 1855. 



In this year a patent was taken out by John Gilbert Martien for 

 refining iron, by forcing air through it as it flowed from the blast- 

 furnace, or cupola, along runners to the puddling-furnace. The proc- 

 ess, as detailed in the patent, was impracticable, and showed internal 

 evidence of not having been worked out on a manufacturing scale. 

 Just after this patent was taken out, we find George Parry, of the 

 Ebbw Yale Works, making the experiment of forcing air through 

 molten cast-iron, on the bed of a reverberatory furnace, by means of 

 perforated pipes imbedded .in the fire-clay bottom. Vigorous action 

 is said to have taken place ; but the metal, through an accident, 

 escaped from the furnace, and the further trial of the process was dis- 

 couraged by the managing director. Two or three months after these 

 experiments, Henry Bessemer took out his now celebrated patent for 

 the production of cast-steel by blowing air through molten cast-iron ; 

 it should be clearly borne in mind that he had been, for a considerable 

 time previously, engaged in experiments on the subject. He first car- 

 ried out his process in crucibles, placed in furnaces, and so arranged 

 that the contents could be tapped from the bottom into molds. 

 Steam or air, either separately or together, and by preference raised 

 to a high temperature, was forced down into the crucible through a 

 pipe. The patent goes on to state that steam cools the metal, but air 

 causes a rapid increase in its temperature, and it passes from a red to 



