262 GEOLOGY OF OHIO. 
is shown in the preceding diagram. The divisions of the clay that 
underlies the coal, and which far exceeds the latter in value, are also 
indicated. 
The composition of the coal can be learned from the following 
_ analyses of Professor Lord: 
No.1. Holden’s new mine, at Mineral Point. 
No. 2. Tuscarawas Coal and Iron Company, tunnel mine. 
No. 1. No. 2. 
MOiIStUre c.ccis cate Ee eee 4.26 3.35 
Molatilenmatter sci bse hecsnk eee eee ee oe 41.61 42.14 
Fixed CaEbomite seh Week eee neater Roane ness 48.08 43.73 
DENI) 0 yesCeP SER EOE ae PER ITAA nN SP a te oe INT a AAD meen ae Ty Oba Nt ET 9 6.10 10.78 
100.00 100.00 
SUlPHUr’ «coe iwcocsvansawascedanercesccaees Weseasseuees oes cee eee ee 2.28 4.77 
The coal has a bright resinous luster, and well defined joints or 
cleavage planes. It mines fairly large, but it is tender and does not 
bear handling well. The lower and permanent parting is a pyritous 
slate. There is also visible pyrites distributed through the seam, often 
in large amount. 3 
The floor of the coal, as shown in the foregoing figure, consists of 
5 feet of plastic clay, below which the valuable deposit of the hard or 
flint clay is reached. This upper clay makes great trouble in mining 
on account of its expansion in the process of slacking. It more than 
doubles its volume as it slacks, and thus necessitates a great amount of 
work in keeping entries open. Sometimes the floors of the entries need 
to be cut down many times before they are given up. When any worked 
portions of the mine are left for a few months, they are practically 
closed by this rise of the floor. 
The roof of the coal generally consists of shales, the entire interval 
between this seam and the Middle Kittanning that overlies it generally 
having this constitution. It gives way easily, and needs constant watch- 
fulness and care. 
The accidents of the seam in this district affect the mining of it 
almost as much as its essential characteristics. There is no known por- 
