178 ANNUAL OF SCIENTIFIC DISCOVERY. 



in the former experiments. The presence of the zinc appeared to offer 

 no impediment to the welding, and the result was a bloom, or bar of 

 iron, the fracture of which presented a most remarkable and beautiful 

 silvery grain, as good, if not superior, in aspect to the finest samples of 

 " Low Moor." Blooms of this iron were rolled out in rods, and tested 

 in the cable-proving machine, and the result indicated from five to ten 

 per cent, higher strength than the best samples of wrought-iron ; thus 

 establishing the fact, that, so far from the presence of zinc being de- 

 structive to the strength and tenacity of wrought-iron, the contrary is 

 the case. I may mention, that bars of iron were heated to a welding 

 heat in the usual manner ; and, on drawing them from the fire for 

 being welded, a handful of zinc filings was thrown on the welding hot 

 surface, and the welding proceeded with. In this severe test no appar- 

 ent impediment to the process resulted ; the iron welded as if no zinc 

 had been present. 



ON THE CHEMICAL CHARACTER OF STEEL. 



THE following views, respecting the chemical character of steel, were 

 set forth, some time since, by Mr. Nasmyth, of England : 



" Were we to assume, as our standard of the importance of any in- 

 vestigation, the relation which the subject of it bears to the progress 

 of civilization, there is no one which would reach higher than that 

 which refers to the subject of steel ; seeing that it is to our possession 

 of the art of producing that inestimable material that we owe nearly 

 the whole of the arts. I am desirous of contributing a few ideas on the 

 subject, with a view to our arriving at more distinct knowledge as to 

 what (in a chemical sense) steel is, and so lay the true basis for im- 

 provement in the process of its manufacture. It may be proper to 

 name, that steel is formed by surrounding bars of wrought-iron with 

 charcoal, placed in fire-brick troughs, from which air is excluded, and 

 keeping the iron bars and charcoal in contact, and at a full red heat, 

 for several days, at the end of which time the iron bars are found to 

 be converted into steel. What is the nature of the change which the 

 iron has undergone, we have no certain knowledge ; the ordinary ex- 

 planation is, that the iron has absorbed and combined with a portion 

 of the charcoal or carbon, and has, in consequence, been converted into 

 a carburet of iron. But it has ever been a mystery that, on analysis, 

 so very minute and questionable a portion of carbon is exhibited. It 

 appears that the grand error, in the above view of the subject, consists 

 in our not duly understanding the nature of the change which carbon 

 undergoes in its combination with iron, in the formation of steel. 

 Those who are familiar Avith the process of the conversion of iron into 

 steel, must have observed the remarkable change in the outward aspect 

 of the bars of iron after their conversion ; namely, that they are cov- 

 ered with blisters. These blisters indicate the evolution of a very 

 elastic gas, which is set free from the carbon in the act of its combina- 

 tion with the iron. I have the strongest reasons to think that these 

 blisters are the result of the decomposition of the carbon, whose me- 

 tallic base enters into union with the iron, and forms with it an alloy, 



