.S7A' WILLIAM SIEMENS, l-.R.S. 



21 I 





Description. 



for magnets 





containing 

 tungsten . 



spades . . . . 



hammers . 



Bessemer steel for rails . . . 



Homogeneous metal armour plates 



Vi ry mild steel from open 



hearth furnace 



Sample before Spiegel was applied 

 Bessemer iron (pure) . 



Carbon per cent. Authority. 



4 

 32 

 3 



25 to : 

 23 



18 

 05 

 trace 



A. Willis 



various 

 Percy 



A. Willis 

 Abel 



Cast-steel containing less than 0*3 per cent, of carbon is no 

 longer capable of being hardened, and should be classed rather 

 as homogeneous or melted iron than as steel, while on the other 

 hand an excess of carbon above 1'4 per cent, again deprives the 

 metal of the quality of taking a temper, and it must then be 

 regarded as approaching in character rather to white cast-iron. 



It is, however, a contested question between chemists whether 

 the presence of a third substance may not be necessary to produce 

 steel. Fre*my, in his celebrated controversy with M. Caron before 

 the French Academy, maintains that nitrogen or cyanogen is a 

 necessary constituent of steel ; the investigations of other chemists 

 appear to confirm this theory, and the old Sheffield practice of 

 mixing leather and other animal substances with the charcoal 

 used in the converting furnace would also seem to corroborate it. 

 M. Fremy's theory probably admits of great extension, and it may 

 be that we should regard steel as a triple combination of iron with 

 carbon and with another substance, taken from a series comprising 

 nitrogen, sulphur, phosphorus, silicon, manganese, tungsten, 

 titanium, tin, silver, and probably many other elementary bodies, 

 each of which entering, in an exceedingly small proportion, into 

 combination with the iron and carbon is capable of imparting to 

 the steel distinctive physical properties. 



NITROGEN. Nitrogen has been found invariably in the stee 

 produced by the ordinary processes. 



SULPHUR AND PHOSPHORUS. Sulphur and phosphorus are 

 commonly regarded as the worst enemies to steel, the one render- 

 ing it " red-short," or incapable of being forged, and the other 



P 2 



