ia 
On the Principles of Iron and Steel, 165 
be Able’ to flate the exa& weight of mixtures united with a 
given quantity of crude iron. 
Some, however, may contend for the exifience of fome 
metallic fubftances along with crude iron, which may alfo 
form part of the unmetallic mafs: we are however unac- 
quainted with any capable of enduring the violent heats ufed 
in manufacturing iron, excepting manganefe ; and this femi- 
metallic fubftance is found in bar iron and fteel, nearly in 
the fame proportion as in crude iron: hence it can form ne 
part of the /wppofed heterogeneous matter expelled during 
the procefs of malleability. 
Steel is a mixture of iron with carbon in an aériform 
ftate*. Carbon is given to iron by heating it violently, un- 
expofed to air, in conta¢t with charcoal duft. The propor- 
tion in which carbon exifts in fteel is various, depending 
upon the degree of purity exiting in the malleable iron 
previous to cementation. In abforbing this principle it 
gains weight; and this augmentation of weicht, by the ad- 
dition of carbon, is dependent upon the reafon already men- 
tioned. Some iron, in paffing to the {tate of fteel, gains 1th 
part of its original weight, while others gain not more than 
-py3th part, 
fpecific gravity than an equal bulk in a gafeous ftate, that is combined 
with caloric, inftead of being combined with themctal. The enormous wafte 
of reul metal, in converting a given quantity of crude into malleable iron, 
4s generally fo great, that, at prefent, I merely with to call the attention of 
artifts to the prevention of this wafte, inftead of fatisfying themfelves with 
faying they had only a given produét, becaufe the crude iron employed was 
of 9s a nature as to be incapable of yielding more. 
* In the works of thofe who haye treated on iron, I have never yet feen 
carbon which exifts in crude iron, diftinguifhed from that abforbed by mal- 
leable iron, in the procefs of converting into fteel. I could adduce many facts, 
which to me appcar conclufive, to prove that carbon exifts in crude iren in 
a concrete ftate, feparable by mechanical divifion ; and that it is united to 
fteel in a gafeous ftate by the combuftion of its bafe, infeparable in any form 
by the moft minute mechanical reduction, 
M3 If 
