2Q2 THE SCIENTIFIC PAPERS OP 



cannot be effected in less than about 36 hours, and that at a great 

 expenditure of fuel for heating the chamber externally. 



This unsatisfactory result directed my thoughts to another 

 method of producing spongy iron by means of a rotative furnace. 

 This furnace consisted of a long cylindrical tube of iron about 8 

 feet diameter, mounted upon antifriction rollers ; the brick lining 

 of it was provided with longitudinal passages for heating currents 

 of air and gas prior to their combustion at the one extremity of 

 the rotating chamber. The flame produced passed thence to the 

 opposite or chimney end, where a mixture of crushed ore and car- 

 bonaceous material was introduced. By the slow rotation of this 

 furnace the mixture advanced continually to the hotter end of the 

 chamber, and was gradually reduced to spongy iron. This dropped 

 through a passage constructed of refractory material on to the 

 hearth of a steel-melting furnace, where a bath of fluid pig metal 

 had been provided. The supply of reduced ore was continued till 

 the carbon in the mixture was reduced to the minimum point 

 before indicated. The rotation was then arrested to prevent 

 further descent of reduced ore ; spiegel was added ; and the con- 

 tents of the melting furnace tapped into a ladle and thence into 

 ingots, as before described. 



This rotary furnace was erected by me at the Landore Works in 

 18G9, and it was so far successful, that the reduction of the ore 

 was accomplished in a comparatively short time. A difficulty, 

 however, presented itself, which led to its immediate abandonment ; 

 it was found that the spongy metal produced, absorbed sulphur from 

 the heating gases, and was rendered unfit for the production of 

 steel ; the spongy iron moreover, upon its introduction into the 

 steel-melting furnace, floated upon the metallic bath without being 

 readily absorbed into it, and was in great part reoxidised and con- 

 verted into slag by the action of the flame in the furnace. 



These experiments convinced me that the successful application 

 of reduced ores could not be accomplished through their conversion 

 into spongy metal, and fully explained to me the want of success 

 which has attended the previous efforts of Clay, Chenot, Yates, 

 and others, to produce iron directly from the ore. On the other 

 hand, I had observed that in melting iron ores no sulphur was 

 absorbed from the flame ; and it occurred to me that by melting 

 ores mixed with fluxing materials in a furnace so arranged as to 



