ON CAST IRON. 



187 



it very easily. A skilful workman succeeded in forging a 

 piece without melting it, and formed a plate of it, which, af- 

 ter tempering, appeared to be very steely. Hence I conceive 

 it follows, that, if cast iron gain in metallization by continu- 

 ing the heat, it loses by the diminution of its oxide a princi- 

 ple, that seems indispensable to the solidity of its texture.] 



If this oxide, which serves the purpose of interlacing the Tough \;ast 



metallized parts, and of preserving a more complete conti- iron > a solution 



i ■> t ■, . • ,!••■*• of oxide of 



guity between them, happen to be deficient, the liquidity of iron in the 



the fused mass cannot avoid being diminished, and its place metaI « 



must be supplied by carbon, to keep up this effect. But 



when the iron owes it liquidity to this new principle, it is far 



from having the same coherence or tenacity as in the former 



case. Whatever may be thought of this opinion by those 



metallurgists, who are engaged in casting artillery, I conceive 



it will be of use to them, to preserve the history of these facts. 



But if we continue for the present to consider the carburet If a carburet, 



of iron as an actual combination, we must allow, that its ex- sti11 a com - 



rr „ pound united 



istence, or its solution in cast iron, affords us an example of a with an excess 



combination, a compound with the excess of one of its ele- °f oneoflts 



elements 

 ments, or, if you please, of another kind of union, to which 



Mr. Berthollet does not appear to me to give a full assent. 



I have examined cast iron obtained with the pit-coal of As- Cast iron im- 



turia in furnaces, that had neither the height, nor strength of P erfe ctlv re- 



° ; ° cluced by pit 



blast, commonly required to reduce iron ore by this combus- coal. 



tible. This cast iron, on coming out of the crucible, boiled 

 till it began to fix. The result was white, blistered masses, 

 fit for nothing but making cannon balls. It was easy to see, 

 that this ebullition was nothing but a continuation of the ef- 

 fervescence, which had not terminated in the furnace. 



Its solution confirmed this opinion, for it afforded infinitely Afforded less 

 less hidrogen than white cast iron. hidrogen. 



The labours of Bergman, Berthollet, and many other sci- ~ gt iron re _ 

 entific men, confirmed by the methods practised in England, tains oxide in 

 to promote the disoxidation of the parts in which this process solutlon - 

 has not taken place, scarcely admit of a do\ibt, that cast iron 

 is nothing but metallic iron serving as a menstruum to a por- 

 tion of its oxide. But are not such solutions so many exam- 

 ples of compounds dissolved in an excess of one or other of 

 their elements ? 



O 2 Sulphurate 



