560 | GEOLOGY OF OHIO. 
12. Big Vein, Salineville. Wormley. 
13. Durham coke (England). 
14. Coke from Mons basin (France). 
The composition of the ash of coke will, of course, be essentially 
the same as that of the coals from which they are made, and such 
analyses have already been given. The sulphur, however, is some- 
what reduced in amount. It may be generally said that } of the 
sulphur in a coal is expelled in the process of coking, or that the coke © 
will retain about three-quarters of the sulphur in the coal. When, 
however, the sulphur exists in some other combination than the sulphide 
of iron, as in the probable organic sulphur compounds alluded to, a 
somewhat larger proportion is expelled in coking. 
The manufacture of coke may be conducted by three methods: 
1. Coking in simple heaps or piles, as in the carbonization of wood. 
2. Coking between walls or in kilns. 
3. Coking in closed ovens or furnaces of various forms. 
1. Coking in heaps. The manufacture of coke in heaps or piles 
is the oldest method for its production, and though still used in some 
districts in England and in this country, it is fast giving way to the 
more perfect and economical process of coking in ovens. 
The heaps are sometimes circular in form, but more commonly 
rectangular, having a length of from 50 to 200 feet. The operation of 
coking in piles is in many respects similar to charcoal making, and 
though simple and requiring little outlay, it is by no means economical, 
as there is a large loss from the unavoidable burning to waste of a part 
of the coal. The yield of coke made in this manner is 20 to 30 per 
cent. less than when the same coal is coked in ovens, and the coke is 
not so dense, and more care is required in the conduct of the operation. 
The coke heaps are made in the same area, and usually at the furnace 
a portion of the yard being set apart for that purpose, which soon be- 
comes covered with the fine coke dust or breeze, which is used for 
covering the surface of the piles. 
Circular heaps are not employed in this country, but they are used 
in some parts of England. At the center of the base, which is from 
25 to 30 feet in diameter, a chimney is loosely built of brick, generally 
circular in section. A number of holes are left in the chimney by omit- 
ting here and there a brick. The coal is piled around this chimney, the 
