417 



in adding ivlinrd iiiaal. M. IVmrcel wont on to say that an 

 aihantauv might le obtained by tapping off the slag at a certain 

 . and, after dephosphorization had taken place, adding the 

 frn-o-manganese ; and then he said, "All this is very complicated. 

 Dr. Siemens himself will acknowledge that this is no longer his 

 simple method. It is a mixture of the Krupp and the forno- 

 convcrtisseur processes" (p. 22). Now he (Dr. Siemens) should 

 be sorry to interfere with the carrying out of Hen* Krupp's pro- 

 cess, but if it consisted in tapping off the slag, the misfortune was 

 that he had done that already ten years ago, and he must, there- 

 f.iv. pardon him for interfering with that part of the process. A 

 very great advantage could be gained through tapping off the 

 silicious slag at a certain stage, and then adding the final quanti- 

 ties of ferro-manganese and silicon iron, if the latter was used for 

 bringing the bath into its final and proper condition. But it was 

 difficult in actual practice to insist upon such nice operations. 

 The tapping off of the slag took time, and his experience was that, 

 after having used it anywhere, and finding that it worked very 

 nicely, the next time he came to the place he found it had been 

 discontinued. Except for the additional trouble it involved, the 

 tapping off of the silicious slag, in order to produce towards the 

 end of the operation a basic slag by adding lime, was a very 

 advantageous mode of working, and one that he had for many 

 years insisted on. 



Mr. Richards had made some interesting remarks, giving the 

 negative results of experiments he had made at Middlesborough, 

 with a view of saving time in deoxidising the metal, by means of 

 silicon and manganese combined, after the blow in the Bessemer 

 converter. He (Dr. Siemens) could confirm Mr. Richards from 

 his own experience, it being the established practice in some of 

 the works where the open-hearth process was carried on, to add 

 silicon iron and spiegeleisen about twenty minutes before the final 

 addition of ferro-manganese, this interval of time being necessary 

 in order to effect the formation and separation of the particles of 

 slag, formed when silicon, manganese, and the oxygen absorbed in 

 the metal combined. This modus operandi, he believed, was first 

 suggested by M. Gautier of the Terrenoire Works. 



M. Pourcel alluded to the rotary process as carried on at 

 Towcester, and said that there could be little advantage in work- 



VOL. I. E E 



