174 On the Blast Furnace in the Manufacture of Iron. 
In the upper half of the fire-room little or no chemical action is 
taking place, the ore, flux and coal, as already stated, simply losing 
their volatile parts. In the bottom of the upper half and the en- 
tire lower half of the fire-room, a reaction is taking place between 
the ore and the carbonic oxide of the ascending column, iron or 
magnetic oxide of iron and carbonic acid being the result. It 
must be borne in mind, that the coal has played no part in this re- 
duction down to the commencement of the boshes. Between 
the boshes, and in the hearth, no reactior appears to take place 
between the ascending and descendi Y masses, but the reduction 
of the ore is completed by the direct action of the coal upon the 
remaining portion of the undecomposed ore, carbonic oxide being 
formed, and here is the first consumption of the coal in its pas- 
sage downwards. \ i 
According to M. Ebelman the ore loses in the fire-room 24 of 
its oxygen by the reaction of the oxide of carbon, and the re- 
maining ;%; disappears in the boshes and hearth in the manner al- 
ready stated, at the expense of from ;%, to 32, of the entire 
amount of charcoal used. : 
The ore being now completely reduced, unites with a portion 
of carbon in the hearth, melts at about 13 inches from the tuyer, 
and descends into the crucible ; and here also the flux combining 
with the impurities of the ore forms the slag which. melts. 
- The coal and the air react upon each other most powerfully 
just in the neighborhood of the tuyer, where the most intense 
heat is produced ; the oxygen becomes converted into carbonic acid, 
which acting upon a portion of the ignited coal, is almost at the 
same moment reduced to carbonic oxide; the moisture of air act- 
mg on the ignited charcoal undergoes the decomposition already 
mentioned, hydrogen and carbonic oxide resulting therefrom. 
When the ore is easy of reduction, the gas at the boshes is rep- 
resented by 100 nitrogen and 52-5 carbonic oxide, plus the quan- 
tity of carbonie oxide and hydrogen afforded by the moisture. 
It must be clearly understood that these rules do not apply to 
every variety of ore. They are especially applicable to the he- _ 
matites and such ores as are either naturally porous, or become 
so in their passage through the fire-room of the furnace, thus in- 
creasing the surface of contact exposed to the action of the re- 
ducing agent, (carbonic oxide, ) so that when it has reached the 
boshes the reduction is nearly complete. 
See ae ghar 
