146 GEOLOGY OF OHIO. 
demand for Ohio cannel at the present time. There are several con- 
siderable deposits that are known in the State, but not one of them is 
now worked on its own account. 
The division between the open-burning and the cementing coals of 
the State is to a certain extent a geographical one. From Perry county, 
southward and westward, all of the coal that is now mined is open- 
burning, except the product of a single mine. From the same boundary, 
northward and eastward, nearly all of the coals, with the exception of — 
the Sharon seam, belong to the cementing variety, though many of them 
possess this property in but a moderate degree. 
The differences between these several classes of bituminous coals 
are not shown in the results of chemical analysis. In other words, a 
knowledge of the chemical composition of a coal does not enable us to 
refer it to one or another of these several varieties. As a rule, the can- 
nels range higher in ash than the cubical coals, but among the latter 
there are very many gradations in this respect. ‘There is no known 
relation between the amount of volatile matter in a coal and the coking 
property, whereby a coking coal can be separated from an open-burning 
coal on the grounds of analysis alone. 
It has been suggested that the coking or open-burning properties 
of coals are dependent upon differences in the vegetation from which 
they are respectively derived. The suggestion is plausible and interest- 
ing, but such connections have not yet been demonstrated. 
CoMPOSITION OF OHIO COALS. 
The results of chemical analyses of Ohio coals, as ordinarily stated, 
comprise the following elements, viz. : 
1. Fixed carbon. 
2. Volatile combustible matter. 
3. Moisture. 
4. Ash. 
5. Sulphur. 
The first two elements are those upon which the value of the coal 
depends, and the terms by which they are designated go far to explain 
themselves. - The fixed carbon is the part which remains after the coal 
has been raised to a bright red heat; the volatile combustible matter is 
the part which escapes as gas under the above named condition, the 
moisture of the coal having been previously expelled. While the 
