SfK WILLIAM SIEMENS, F.R.S. 235 



any silica, it is necessary to add some lime or other fluxing 

 mat' rials, but it is desirable to employ ores containing little 

 gan^ue, in order not to encumber the furnace with slag, reserving 

 the poorer ores for the blast furnace. The ore should, moreover* 

 be in pieces ranging from the size of a pea to that of a walnut, in 

 order to be pervious to the reducing gases. If ores in the form 

 of powder are employed, it is necessary to mix them with about 

 10 per cent, by weight of light carbonaceous materials, such as 

 dry peat, wood, or charcoal. 



The metallic bath having sufficiently increased in the course of 

 from three to four hours, the supply of ore is stopped, and that 

 contained in the hoppers is allowed to sink. Before the hoppers 

 are empty, a false cover of cast iron, lined with clay at its under 

 side, is introduced, being suspended from above by a strong wire, 

 in order to prevent the access of flame to the interior of the empty 

 hoppers. Charcoal and ore are filled in upon the top of this false 

 cover, and, on cutting the wire, afterwards form the commence- 

 ment of the succeeding charge. 



When all the ore has disappeared, the metallic bath is tested 

 as before described in reference to the melting of scrap. If it 

 should be partially solidified, cast iron is added to re-establish 

 complete liquefaction ; but if, on the other hand, the bath con- 

 tains an excess of carbon, oxidising agents may be added as 

 before described, in requisite proportion. From 5 to 8 per cent, 

 of spiegeleisen is then added, and the furnace is tapped as already 

 described. 



The quality of the steel produced is chiefly dependent upon the 

 quality of the ore, but considering that ores of great freedom from 

 sulphur, phosphorus, or arsenic can be had in large quantities, 

 this process contains all the elements for producing steel of high 

 quality. 



Having tried a variety of ores, I do not attach much im- 

 portance to their precise composition, so long as they are 

 comparatively free from gaugue, and from sulphur and phos- 

 phorus, the heat being sufficient to reduce the most refrac- 

 tory. My experience is, however, as yet limited to experimental 

 working. 



I hoped to have been in a position to have given you the 

 temperature of this furnace, as determined by an electric resistance 



