Qo On the Converfion of Iron into Caf? Steet 
genation. They fuggefted to our brother, C. Clouet, the 
idea of fearching for a confirmation of a new kind, by trying 
to make foft iron pafs to the ftate of fteel by cementation 
with the diamond, 
It has hitherto been confidered as certiin, that iron does 
not melt but by pafling to the ftate of fteel or caft iron. But 
jn what ftate does the carbon enter into that combination ? 
It might be conjetured, that it is in the ftate of plumbago, 
or oxyd of the firft degree; fince that which is feparated by 
acids exhibits the brilliant blacknefs and incombuftibility 
_ which form its principal charaéters. Hence fome were in- 
clined to conclude, that the carbon entered ipto this union in 
the ftate of an oxjdule; that confequently the carbon em- 
ployed in the cementation of ftee] began by deoxydating it- 
felf to a certain degree. This was even in fome meafure 
proved; as the carhon employed for this operation was in- 
deed found to have a more brilliant afpeét, and nearly refifted 
jncineration, like carbon in a mafs burnt in clofe veffels, 
But if carbon really burns in the cementation of iron, it 
aught to difengage from it oxygen gas. This is a queftion 
which I have endeavoured to refolve by experiment. 
I cemented {mall bits of iron in a porcelain retort, which 
in the preceding operation had received a vitreous coating, 
and which confequently was no longer permeable to air, 
Thefe fragments were all furrounded, on every fide, by char- 
coal of beech pulveriled, and yery dry. The retort was put 
into the reverberating furnace, and a tube connected to it 
and carried under a receiver filled with mercury. There was 
difengaged a quantity of elaftic fluid, compofed of carba- 
ape hydrogenous g eas and carbonic acid gas, the laft’ of 
which was at firlt only O°II in bulk ; ; towards the middle of 
the experiment, 0° 135 and at the.end, 0:15. 
The converfion of iron into fteel being found enly little 
advanced, after three hours and a half expofure to the fire, 
we put the fame iron and the fame carbon again into the 
retort, and expofed it to the heat of a three- blatt- furnace, 
This time there was only a very fmall quantity of gas ; but 
it was ftill carbonated hydrogenous gas mixed with carbonic 
acid Bas, and always with the fame progreffion of the latter; 
re) j which — 
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