IRON MANUFACTURE. 473 
ous limestone,” of the barren coal measures, which is so important a 
feature of the Coal Measures, from Linton to some distance below 
Steubenville. At Bellaire, Wheeling, etc., there is an inexhaustible 
supply of limestone in the stratum, immediately overlying Coal No. 8, 
the Pittsburgh coal, usually about 20 feet thick. Some portions of 
this are sent up the river and used at Steubenville and Mingo. This 
is the same stratum from which the furnaces obtain their supply at 
Pittsburgh. Analyses of these limestones have been made by Dr. 
Wormley, and appear in the report of the Chemist (Report of 1870). 
As has been said, the fuel of this region is almost entirely Connells- 
ville coke. At Leetonia, however, and at Steubenville some coke is 
made from the Ohio coal, the furnaces of the Cherry Valley Iron 
Works using almost entirely, coke made in bee hive ovens at the fur- 
nace. The Grafton works also have some fifty ovens, and while they 
purchase a large amount of Connellsville coke, also, when prices of labor 
and coal are favorable, run on coke made at their works. 
As at many other works in the State, mill cinder is largely used in 
the manufacture of iron at the various works in the Steubenville dis- 
trict. The peculiar character of this material in its relation to smelting 
will be discussed further on. 
The Hocking Valley District. 
The iron works designated as belonging to this region comprise 
those situated in Hocking, Perry and Athens counties. They forma 
distinctive class of works, using the native ores of the Lower Coal 
Measures and the famous furnace coals of the Hocking Valley. They 
are allied to the numerous charcoal furnaces of the Hanging Rock 
region, representing the application of raw coal to much the same class 
of ores as the charcoal furnaces smelt with charcoal. The furnaces are 
mostly of recent date and present peculiarities of working of much in- 
terest to the metallurgist. Of late years the Lake Superior ores have 
been used more and more in mixture with the native ores, these latter 
having somewhat disappointed the expectation at first entertained as to 
their richness and purity. ‘The establishment of railroads all through 
the district has followed its mineral development, and it is now, through 
the Columbus & Hocking Valley and the Ohio Central Railroad brought 
well into communication with the railway system of the State. The 
works of the valley are mostly comprised between Logan, Hocking 
