3J4 ProduSlion of Steel from Soft Iron by the Diamond. 



But if the charcoal be really unburned in the cementation of iron, there muft be a difcn- 

 gagement of oxigen gas. I have endeavoured to refolve this qireftion by experiment. 



I cemented fmall pieces of ir,on in a porcelain retort, which had received by a previous 

 operation a vitreous coating, andconfequently was no longer permeable by the air. Thefe 

 pieces of ij"on were furrouiuled on all fides by very dry powdered charcoal of beech. 



The retort was placed in the rcverberatory furnace with an adjutage, bearing a fyphon, 

 plunged beneath the furface of mercury, under an inverted glafs veffel. A large quantity of 

 elaftic fluid was difengaged, confifting of carbonated hydrogenous gas, and carbonic acid ; 

 the latter of which was at the commencement o, 1 1 of the volume} towards the middle 0,13 ; 

 and towards the end 0,15. • 



The converfion of iron into fteel being but little advanced, after the fire had been con- 

 tinued for three hours and "a half, the fame iron and the fame charcoal were again put into 

 the retort, and fubje£ted to the heat of a large furnace, urged by three bellows-pipes. There 

 ■was now no more than a very fmall quantity of gas; but it was carbonated hydrogen, mixed 

 with carbonic acid, witlva progreflive flow increafe; fo that the latter, which at firfl formed 

 only the 0,07 of the bulk, amounted in the laft portions to 0,12. The iron was now con- 

 verted into fteel, and the pieces were even joined together by a commencement of fufion. 



It is very probable that part of the carbonic acid, coUedted in this operation, was formed 

 at the expence of die remaining charcoal, with oxigen which was difengaged ; but the con- 

 ftant prefence of hydrogen leaves nothing certain in the refult, but the difliculty of entirely 

 depriving the charcoal of the lalt portions of water it contains. 



I muft here obferve, that this experiment does not appear eafy to be reconciled with the 

 opinion of fome chemifts, that hydrogen has a greater attra£lion for oxygen than charcoal 

 has; an opinion founded on the confideration that coal is precipitated in the eudiometer of 

 Volta, when a mixture of oxygen and carbonated hydrogen gafes are detonated, and the 

 quantity of oxygen is not fuiKient for faturating the two bafes. I fay that this ele£live at- 

 traftion does not take place in my experiment, in which it cannot be doubted that the tempe- 

 rature is fufliciently elevated to produce water by the union of oxygen and hydrogen, and there 

 is nothing in this cafe to give a preference of the oxygen for the carbone. 



This confideration appeared to me to give a new intereft to the experiment propofed by 

 Citizen Clouet, I did not hefitate to ufe one of the diamonds of the polytechnic fchool for 

 this purpofe, purfuant to the authority I had received from the council ; being perfuaded that 

 if it fliould difappear in this operation, by the mere expofure to an elevated temperature, in' 

 contaft with iron, without the prefence of air, nor any other oxigenating matter, the fail would 

 well repay the facrifice. Befides which, its form, colour, and irregular cryftallization, ren- 

 dered it of little value, even as an objedl of inftrudlion. 



Citizen Clouet had himfelf prepared a fmall crucible of foft iron, exprefsly forged out of 

 chofen heads of nails. Its form was that of an eight-fided folid. See fig. i. Plate XVI. and 

 - it was clofed by a ftopper of the fame metal, well fitted, fig. 2. 



This crucible was intended to be placed in a Heffian crucible, furnifhed with a cover, 



well 



