500 GEOLOGY OF OHIO. 
excessive cheapness and smal] quantity of the fuel used, the amount of 
which is about one-tenth that of the ore, though it is not accurately 
measured. One object of roasting is the expulsion of sulphur, which is 
quite incompletely attained in piles. And where the ores contain con- 
siderable, as is the case with some of the gray ores, the imperfect 
expulsion of the sulphur may lead to serious trouble in the working. 
This description of the method of roasting in piles applies to all the 
furnaces using native ores in the State, the fuel being, as stated, char- 
coal breeze at the charcoal furnaces, and coal slack at the coal furnaces. 
The use of kilns for roasting ore, which has been found so advantageous 
in many parts of the world, has been almost untried in Ohio. At the 
Monitor furnace, however, four miles from Ironton, an iron kiln has 
been built out of the upper part of the mantle of an old furnace; this 
primitive kiln, consisting of an iron shell about 8 feet in diameter, lined 
with fire-brick, and supported at the bottom on stone blocks, and having 
a total height of only 17 feet, is charged with ore mixed with charcoal 
breeze, and the burned ore drawn out at the bottom. This burns the 
ore in from twenty-six to thirty hours, the ore is uniformly burned, and 
does not loup or melt together. This one kiln furnishes nearly 
enough ore to supply the furnace. The charges in this kiln are not 
weighed, and consequently precise figures as to the amount of coal used 
could not be obtained, but the filler states that about an inch of breeze 
was used to a foot of ore. Experience with good English kilns has 
shown that in proper kiln-roasting one-fifteenth to one-twentieth the 
weight of the ore is all the fuel that is required. 
The new furnace now being built at Hanging Rock, by Means, 
Kyle & Co., is to be equipped with kilns built after a slightly modified 
plan, of the “Gjer” kiln. This kiln, having a diameter of 173 feet 
at top, 19% feet at middle, and 133 feet at bottom, is provided with a 
series of flues by which air is brought to a cone of cast iron in the center 
of the kiln. The advantage of this arrangement is that the ore is 
prevented from overheating, and is fully supplied with air, by which 
all the lower oxides of iron are converted to sesquioxides. Figure I 
gives a sketch of ths kiln. These are the only cases of kiln-roasting 
in the State. The blackband ores of Tuscarawas and Stark counties 
are roasted in piles with coal slack, or in the case of the Mineral Ridge 
blackbands, where the proportion of carbonaceous matter is large, are 
