280 THE SCIENTIFIC PAPERS OP 



In the discussion of the Paper 



"ON THE PEACTICAL WORKING OF DANKS'S 

 ROTARY PUDDLING MACHINE," 



By MB. JOHN LESTEB, Wolverhampton, 



ME. SIEMENS * said he congratulated the members of the Iron 

 and Steel Institute on the very able reports which they had re- 

 ceived on the subject of Danks's rotary puddling furnace. He 

 had listened to these reports with great interest, and it seemed as 

 though the facts brought out conclusively proved the value of the 

 apparatus that had been brought before them. That was not the first 

 attempt at a rotating puddling apparatus, as they well knew. He 

 had, many years ago, seen the apparatus, erected, at Dowlais 

 Works, by Mr. Menelaus, and he looked with regret at the 

 difficulty which prevented its practical success. That difficulty 

 had, to all appearance, been overcome by Mr. Danks, by the in- 

 troduction of a judicious fettling material. In the report mention 

 was made of one or two points which called for remark on his 

 part. In one of them, by Mr. Jones, a paper "On Puddling 

 Iron " was mentioned, which he (the speaker) read some years 

 ago before the British Association, setting forth a theory of 

 puddling which had been much criticised by practical ironmasters, 

 but which was very- fully confirmed by the results obtained in the 

 Danks furnace. The reports in question expressed some surprise 

 at the greater yields realised in puddling grey iron than in puddling 

 white iron. Now, he would submit that his paper furnished a 

 complete explanation of that result. He there endeavoured to 

 prove that puddling was, strictly speaking, a chemical reaction 

 between fluid cinder and fluid cast-iron, and he showed that for 

 every pound of carbon in the metal, 3*5 pounds of metallic iron 

 have necessarily to be reduced and added to the charge. In like 

 manner, for every pound of silicon in the metal 2*8 pounds of 

 metallic iron had to be produced. If, therefore, his theory was 



* Excerpt Proceedings of the Iron and Steel Institute, 1872, pp. 293-295 and 

 314-315. 



