64 CemhuJJihility o/Iron.-^Stet-/. 



III. 



InJIrunions concerning the ManufaElure of Steel, and its Ufes. By VaXDERMONDE, MokgE, 

 and BerTHOLLET. Pubiyijed by Order of the Committee of Puhlic Safety*. 



I 



Preliminary Ohfervations. 



RON is a combuflible body. It lofes its metallic properties by being burned. When 

 iron filings are expofed to flrong heat in a crucible, and frequently ftirred to bring the 

 parts fucceflively in contaft with the air, the metallic afpeiSt difappears. It aflumes a 

 brick-duft colour, and is found to have increafed in weight. Part of the air of the atmo- 

 fphere has combined with it, and produced this change. This portion of the atmofphere 

 is called oxygene. 



Iron is found in this ftate in its ores. The procefs of extracting it from thefc ores prin- 

 cipally confifls in depriving it of oxygene. 



Charcoal has the property of efFedling this change. During combuflion it abforbs and 

 unites with oxygene, and it will attradl the oxygene from iron when thefe fubftances are in 

 contadl at an elevated temperature. Thefe effefls of air and charcoal are very perceptible 

 when tin is kept in fufion. A grey pellicle is foon formed on the furface, which has no 

 metallic fplendour. If this pellicle be taken off, a fecond is formed, and in this manner 

 the whole of the tin may be converted into a fubftance refembling earth, and known by the 

 name of drofs. By expofure of the drofs to heat, together with a fmall quantity of char- 

 coal pow4er, tallow, or refin, the oxygene is abforbcd by thefe combuftible fubftances, and 

 the tin becomes reduced to the metallic flate. 



Charcoal not only poflefTes the property of depriving the iron of the air which was 

 united with it, but it is alfo capable of being diffolved in the iron in a ftrong heat, and by 

 this folution it communicates new properties to it. It changes it into fteelf. 



Crude or call iron may be confidered as a metal not completely reduced, which confc- 

 quently retains a portion of the bafis of air, or oxygene, to which it was united in the ore ; 

 and as this reduftion may be carried farther according to circumftances, the confequcnt 

 variations are among the leading caufes of the different properties we obferve in caft iron. 

 The white caft iron accordingly holds in folution much oxygene and little charcoal ; the 

 grey caft iron on the contrary contains more of this laft fubftance, but is much more pcr- 

 feftly deprived of oxygene. A greater proportion of coal muft be ufed in the furnace to 

 obtain this laft. The properties of thefe two kinds of iron depend only on this difference : 

 the former is more brittle and fufible, but it is eafy in the refining furnace to deprive it of 

 oxygene by the aftion of ignited charcoal, which combines with this principle. The fe- 

 cond has retained lefs oxygene, but contains much more charcoal. It is fofter, and prefer- 

 able for fuch ufes as require this foftnefs ; but it is more difficult to convert it into 

 malleable iron, becaufe a larger portion of coal is required to be deftroyed, and in this 

 ftate it confiderably refifts combuftion. 



• I have -omitted a few political reflections of a temporary nature contained in this memoir. 

 + Other ingredients enter into fteel,and are perhaps effential to it, particularly phofphorus. See the analyfis 

 ofVauquefin. Phiiof. Journal, I. 252. 



Forged 



