Properties of Steel,--Hard cojl inn, roj 



Wc have remarked that caft iron, fufficiently abounding with charcoal, aflumes the ap- 

 pearance of the white crude iron when it is caft. in plates or too fuddenly cooled. To af- 

 certain its nature, nothing more is neceflary than to clean its furface j and by the more or 

 lefs grey or dark colour of the fpot produced by nitrous acid, a judgment may be formed of 



its quality. 



Vandermonde, Monge, Berthollet. 



Annotations upon the Report concerning Steel. 



I. Notwithstanding the great light which has been afforded by the labours of Rinman, 

 Bergman, Vauquelin, and other chemifts, together with the learned authors of the fore- 

 going paper, we have ftill much to learn refpefling the caufes of th^ feveral qualities of 

 fteel to be found in the market. Much of this information might probably be obtained by 

 diligent enquiry, and the ufual methods of examination. It is yet to be fliewn by experi- 

 ment, whether pure iron united with carbon conflitutes the beft fteel ; or whether any ad- 

 ditional ingredient, fuch as phofphorus, manganefe, or other metallic matter, may not be of 

 advantage. If the former pofition be true, the beft fteel-iron will be that which is the 

 pureft; and the beft cement will be the fimpleft coaly matter. On the contrary, if the latter 

 fuppofitions fliould be well founded, the goodnefs of our fteel will depend, not only upon 

 the component parts of the bar iron, but likewlfe on the adaptation of the cement proper 

 for its converfion. Mr. Duhamel, in tlie Encyclopedic, article Acier, p. 462, found that 

 the charcoal which had been ufed in making fteel was not fit to be ufed again, by reafon of 

 the flownefs of its operation. In this cafe it feems probable that, though enough of car- 

 bone remained, yet fonie more volatile ingredient had been expended in the firft procefs. 

 Our authors have well explained the advantage of the iron being well forged and found 

 throughout, previous to its expofure to the cementing procefs. • 



1. The grey crude iron may be confidered as iron faturated with as much plumbago or 

 carburet as it can hold in folution at a very elevated temperature. When it is fuffered to 

 cool flowly, as in foft cafting, the plumbago appears to feparate by hafty cryftallization 

 tlirough the whole mafs,as may frequently be obferved in its fracture, and as has been fliewn 

 by plunging a cold bar of iron into the fufed metal, and withdrawing it covered with the 

 carburet which precipitates upon it. When this iron is poured into a cold mould of me- 

 tal, or fuffered to run to a great diftance from the aperture of reception, in fand, or other- 

 wife if a bar of this metal be heated to whitenefs, and plunged in water, it becomes very 

 h»rd ; more fo than fteel tools of any defcription are ufually made, and is very white, and 

 clofer grained in its fracture. .The hardnefs muft depend upon circumftances in its aggre- 

 gation, to explain which we pofiefs no data ; but I apprehend the whitenefs to be an evi- 

 dent confcquence of the union between the iron and the plumbago continuing to be nearly 

 as intimate as it was at the white heat. It is very probable that, in all cafes of the hardening 

 of other fteels containing lefs carbone, a iimilar efFefl may take place. 



3. The laminating rollers, concerning which our authors offer nothing but conjeiSlure, 

 are made cf this iron caft in fand, or metallic moulds of confiderable thicknefs. I am in- 

 formed by founders who make them, that the external hard part does not penetrate to a 

 greater depth than about three quarters of an inch ; and that the hardnefs is not greater 

 than that of a good graver. The procefs of turning them in the lathe., iu faQ, ftiews this. 



Vol. JI.— June 1798. V Far 



