SIR WILLIAM SIEMENS, F.R.S. 391 



process, which is compensated for, however, by the correspond! ug 

 advantage in favour of the ore process, that it is not dependent 

 up' in the irregularities appertaining to scrap metal, and upon the 

 purifying action produced upon the fluid metal first by the oxide 

 and thereafter by the lime. It has been found generally that for 

 small applications the scrap or Siemens-Martin process is the more 

 advantageous, while for large applications the ore process has the 

 advantage. 



For the production of steel of special quality, such as is em- 

 ployed for boiler and ship plates and castings, the process is 

 different only towards the eud of the operation from that already 

 described. The reduction is carried to a still lower degree than 

 O'l per cent, of carbon, and in order to make sure that the right 

 degree of carburization is attained, chemical analysis of a sample 

 is resorted to. Instead of spiegeleisen, a rich ferro-inanganese is 

 employed, together with a small proportion of silica iron (a pig 

 metal containing about 10 per cent, of silicon), which latter metal 

 has the effect of taking up oxygen from the fluid iron, and thus 

 preventing blow-holes in the casting. Another method of con- 

 solidating steel is that which has been introduced and so success- 

 fully carried out by Sir Joseph Whitworth. The steel upon which 

 he operates is made upon the open hearth of the furnace in the 

 manner I have described ; but steel when it is poured from the 

 ladle into the moulds shrinks, and during shrinkage little air- 

 spaces or hollows are formed, which break the continuity of the 

 steel, although the cavity may afterwards be closed. Sir Joseph 

 Whitworth, by applying great pressure through hydraulic agency 

 to the steel while in the fused condition, closes up these cavities, 

 and steel is thus produced perfectly continuous in its nature, and 

 of such great hardness and tenacity combined, that when put, for 

 instance, into the form of shells, some of these shells have gone 

 three or four times through thick iron armour, and have been 

 quite fit to go into the gun again. 



The rich ferro-manganese now introduced into the market 

 affords the steel-maker great facility for producing sound metal, 

 notwithstanding its admixture with a considerable amount of 

 impurities, notably of sulphur and phosphorus. By its means 

 such inferior irons as the Cleveland can be rendered suitable for 

 the production of steel rails, and large contracts have been carried 



