41 8 THE SCIENTIFIC PAPERS OF 



ing that process, because the removal of phosphorus must depend 

 on finding oxide of iron in the slag. It was quite true that it did 

 do so, but at the same time Dr. Siemens thought that the rotary 

 process was a most effectual and thorough one for the removal of 

 phosphorus, or rather for the production of a metal free from 

 phosphorus. He was much surprised at that portion of M. Pour- 

 eel's remarks, because on the preceding page he said, "In this 

 operation only an imperfect reduction of the ore is obtained, and 

 if the phosphate of iron can be partially reduced at a low tempera- 

 ture, nearly all the phosphoric acid remains in the slag, and as 

 phosphorus was generally present in ores only in the state of 

 phosphate of lime, it was not reduced by the ordinary reducing 

 action of the furnace" (p. 15). He (Dr. Siemens) found, in fact, 

 that in operating upon ore containing phosphorus, the phosphorus 

 never went to the metal ; it remained in the oxidised condition, 

 and he had been enabled to produce metal almost entirely free 

 from phosphorus from an ore containing a very considerable per- 

 centage of phosphoric acid in combination. It was necessary, in 

 order to cany out the process properly, to tap off the first slag 

 before the metal was brought into the form of balls. This first 

 slag contained certainly not an excessive quantity of oxide of iron, 

 and as much as 3 or 4 per cent, of phosphorus. If done 

 systematically, there was no great difficulty in obtaining metal 

 free from phosphorus without incurring great loss. The cinder 

 must be a rich cinder in order to produce the welding quality of 

 the ball. He could bear his testimony to the great value of 

 M. Pourcel's paper, which opened out a very important subject for 

 discussion. 



The, President asked Dr. Siemens whether he had anything to 

 say about the last paper that of Mr. Bull. 



Dr. Siemens said, that with regard to the last paper read, they 

 had in it the revival of a very old friend. He had heard of the 

 blowing in of steam into molten metal even before the days of 

 the Bessemer process, when their friend Mr. James Nasmyth pro- 

 posed and patented such a plan. Sir Henry Bessemer himself had 

 also proposed to blow steam through the metal. There was, 

 therefore, nothing new in the conception. At the same time, he 

 did not doubt the chemical reaction, but, as had already been 

 pointed out, he doubted very much its practicability, because when 



