318 THE SCIENTIFIC PAPERS OF 



Mr. Hackney, after paying the high compliment which was due 

 to Mr. Bessemer for the introduction of his process, had referred to 

 one process with which Dr. Siemens's name had been associated. 

 That process might perhaps be appropriately called the chemical 

 process, or the cooking process, to use a more vulgar expression ; 

 because, given a hot receptacle, such materials were put into that 

 receptacle as would, when melted together, produce steel of the 

 quality required. The beginning of the operation must be a fluid 

 bath, and the material natural for such purpose was pig metal. To 

 this pig metal, when heated to a temperature exceeding 2,000 

 centigrade, either scrap iron, scrap steel, puddled blooms, or iron 

 sponge might be added, and thus a bath might be obtained, which 

 would gradually come to contain less and less carbon, until it was 

 reduced to the condition of fluid iron. It then received such 

 additions as would give it the necessary manganese, carbon, or 

 other substances, to make steel of the required quality. This 

 process had the advantage that samples could be taken out, from 

 time to time, in order to make sure that the operation was going 

 on properly, and that the chemical and physical qualities of the 

 material were such as might be desired. The essential condition 

 for carrying out such a process was a very high temperature , it 

 was perhaps the highest temperature used in the arts, excepting 

 only the fusion of platinum. Considerable difficulty had existed, 

 at first, in obtaining a vessel to withstand such heat, continuously, 

 and the only substance capable of doing so was silica, containing 

 only from 1 to 2 per cent, of binding material. He noticed 

 diagrams of the furnaces in which the processes were carried out ; 

 and one diagram of a modified form of the furnace, by M. Pernot, 

 which was certainly ingenious. The bath was circular, and was 

 rotated on an inclined axis ; and the pig metal flowing round and 

 round in that vessel would wash over any solid substance put into 

 it. He rjowever doubted very much whether such a vessel would 

 resist the high temperature which was necessary for the production 

 of mild steel by that process. He understood it was used at 

 St. Etienne, in France, where engineers were content to have steel 

 rails containing 0'8 per cent, of carbon, which melted at a much 

 lower temperature than the mild steel required in this country. 

 Nor would it probably work out altogether satisfactorily for the 

 process of producing steel from pig metal and ore ; because, in that 



