S7K WILLIAM SIEMENS, F.R.S. 335 



IHtling unless it was of a very strong nature, that is to say of 

 it very pure oxide slipped down and did not stand up so well to 

 i:s \vork as on the vertical side. 



In Vie discussion of the Paper 



"ON IMPROVED CASTING ARRANGEMENTS FOR 



THE SIEMENS-MARTIN PROCESS," 



By ME. MICHAEL SCOTT, 



DR. SIEMENS * said the paper referred to a subject which was 

 one of considerable practical interest. At present they usually 

 tapped the metal into moulds, as they were aware, which were 

 stoppered at the top, and there was a good deal of uncertainty 

 as to the amount of metal which they filled into these moulds. 

 The metal, if it was at all frothy, boiled and gave only uncertain 

 indications of its height in the moulds, which made it difficult for 

 the workmen to stop the flow of fluid steel at the right moment. 

 There was another effect resulting from the mode of filling at the 

 top, viz., atmospheric air was carried in and mixed with the steel, 

 to be liberated again at the moment of solidification, and thus 

 giving rise to spongy metal. It was well known in ordinary practice 

 that gases were set free at the moment of congelation in the moulds ; 

 the steel seemed to take up air, which was, he thought, combined 

 with iron, forming a sub-oxide, which oxide of iron appeared to be 

 dissolved throughout the mass, without combining with the carbon 

 contained in the steel at the high temperature. The temperature 

 of steel being in excess of the point at which carbon and oxygen 

 combined, such metal might be kept for any length of time in a 

 fluid condition, at that temperature, without getting rid of the free 

 oxygen which was evolved at a lower temperature in the moulds. 

 It had been the endeavour of several gentlemen, both in this 



* Excerpt Journal of the Iron and Steel Institute, 1876, pp. 161-163, 165- 

 168. 



