5Y/? WILLIAM SIEMENS, J-.K.S. 



239 



mented by some additional chemical facts and observations, in 

 to render the puddling process perfectly intelligible, and to 

 into relief the defective manner in which it is at present put 

 into practice, involving, as it does, great loss of metal, waste of 

 fuel, and of human labour, and an imperfect separation of the two 

 hurtful ingredients, sulphur and phosphorus. 



SILICON. In forming (by means of the rabble) an intimate 

 mechanical mixture between the fluid cast metal and the cinder, 

 the silicon contained in the iron is brought into intimate contact 

 with metallic oxide, and is rapidly attacked, being found afterwards 

 in the cinder in the form of silicic acid (combined with oxide of 

 iron). The heat of the furnace is always kept low during this stage 

 of the process, and the flame is maintained as reducing as possible. 



CARBON. The disappearance of the carbon from the metal is 

 accompanied by the appearance of violent ebullition and the 

 evolution of carbonic oxide, which rises in innumerable bubbles to 

 the surface of the bath, and burns (in an ordinary puddling 

 furnace) with the blue flame peculiar to that gas. In puddling in 

 a regenerative gas furnace this blue flame cannot be observed, 

 because the flame of this furnace is strictly neutral, and there is no 

 free oxygen present to burn the carbonic oxide rising from the fluid 

 mass, a circumstance which by itself explains the superior results 

 obtained from the gas furnace. 



It is popularly believed that the oxygen acting upon the silicon 

 and carbon of the metal is derived directly from the flame, which 

 should, on that account, be made to contain an excess of oxygen, 

 but the very appearance of the process proves that the combination 

 between the carbon and oxygen does not take place on the surface, 

 but throughout the body of the fluid mass, and must be attributed 

 to reaction of the carbon upon the fluid cinder in separating from 

 it metallic iron ; while as the removal of the silicon is still more 

 rapid, and is effected under a reducing flame, there is strong 

 evidence that it also is oxidized rather by the oxygen of the cinder 

 than by the flame.* 



But it has been argued that, although the reaction takes place 

 below the surface, the oxygen may, nevertheless, be derived from 



* At page 258 is appended a Table showing the comparative quantities of 

 carbon in various kinds of iron and steel. 



