31 
nitude, and may be remedied in a great measure by an aug- 
mentation of blast. The grand destructive power, we are 
decidedly of opinion, resides in the oxygen and hydrogen 
gases, entering the furnace along with the air, in the form of 
vapour, but which are immediately decomposed, or separated, 
by coming in contact with the ignited combustibles in the 
furnace. 
To render our ideas upon this intricate subject more in- 
telligible, we must first take a short view of the phenomenon 
of combustion, the various matters used, the action of each, 
and the changes effected thereby in the reduction of iron by 
combustion, or in the blast furnace. 
The subject, it must be confessed, is yet involved in much 
obscurity, and, sensible of our very imperfect acquaintance 
with what is known, it is with considerable diffidence we sub- 
mit the following conjectures upon it. The materials neces- 
sary to make crude, or pig iron, are ironstone, which in this 
vicinity is iron, combined with oxygen and argillaceous earth, 
or alumina, limestone, or lime united to near an equal weight 
of carbonic acid gas, and coke, which is carbon mixed with 
sundry saline and earthy substances. 
When these matters are intermixed in a furnace in proper 
proportions, the cokes lighted, and the blast introduced, 
consisting of the gases, &c. we have before enumerated, we 
imagine these phenomena take place. The free oxygen of the 
air unites with part of the carbon of the cokes, and forms 
carbonic acid gas, or carbonic oxide ; this gas, or oxide, 
having a much inferior capacity for caloric, takes up some- 
what less than one-third of the heat evolved from the oxygen ; 
the redundant two-thirds serve to raise the temperature 
of the other materials to the point of fusion. It is then that 
the lime, (from which the carbonic acid gas is previously 
driven off by the heat,) combines with the clay of the iron- 
stone, and perhaps some portion of the metallic oxide, (we 
suppose this, because it is said that the earths lime and 
