Iron, 
US 
i iron mutually possess towards each other* In the case of 
the iron separating in an oxygenated state destitute of car- 
bon, it immediately falls a prey to its affinity for oxygen* 
In the latter case* the iron, being completely carbonated* 
resists decomposition by the sacrifice of a very small por- 
tion of its carbon ; it further proves, that the affinity of 
oxygen is greater to carbon than to iron ; and that, before 
iron becomes oxydated, all the carbon is taken up. 
The continuity of the particles of splint coals renders 
the coaks of difficult combustion, capable of withstanding 
a most powerful discharge of air, in quantity and in the 
degree of compression, without entailing effects similar 
to those produced with the use of softer coals : this ren- 
ders the operations with splint coal less subject to casualty 
and to change. Carbonated iron with a proper blast is 
; more uniformly obtained, and frequently a very superior 
quantity* Similar effects are produced with the clod coal* 
but in a more eminent degree. Discharging-pipes are 
used four inches in the diameter, and the compression 
only equal to two pounds on the square inch ; yet the 
same fatal effects are not known as in the use of soft coal, 
which, with such a column of air, would require the pres- 
sure to be equal to 3 1-2 upon the square inch at least. 
5th, Upon the form and construction of the discharg - 
! ing-pipe, effects of more considerable importance depend 
than is either generally allowed or even conceived. At 
; some iron- works, no peculiar shape is adopted : if the tube 
I is sufficient to convey the air, and the mouth of it nearly 
! of the size wanted, the interior construction is entirely 
overlooked. This indifference, however, is by no means 
| general : variously constructed pipes are used at different 
works, and at some places it is preferred to throw in the 
air from two pipes whose areas are only equal to one of 
the usual size.' 
T 
