564 GEOLOGY OF OHIO. 
basin of the Loire, France, for coking the very fine coal which could 
not be coked well in the other forms of heaps. 
In plan they are rectangular, while the vertical section is trape- 
zoidal. The fine coal is packed and held in position by a plank coy- 
ering of suitable size, vertical, longitudinal and cross channels be- 
ing formed byg wooden bars, which are removed when the heap is 
completed. This process requires great care in the construction of the 
heap, is somewhat difficult to manage, and is not economical in its 
results. The yield of coke obtained with the French coals was 50 to 
55 per cent. 
Coking between walls. A peculiar method of coking between walls 
was practiced for a long time in Upper Silesia, and afterwards was 
introduced into Westphalia and France, where it was known as 
the Schaumbourg Furnace. This furnace, used in Silesia, consists 
of rectangular walls of masonry, 8 feet wide by 54 feet long, in- 
side. The floor of the enclosure is made of cinder, broken small ° 
and well packed, on which fire-brick are placed on edge, thus secur- 
ing a good drainage and a dry bottom. The inside of the walls are of 
fire-brick, while the exterior is of common masonry. In each side- 
wall are built a row of holes opposite to one another, and about 2 
feet apart, and from them vertical chimneys open on to the top of 
the wall. When the kiln is to be charged, one end, is closed by fire- 
brick, and then through the other fine coal is wheeled in and spread on 
the bottom, wetted and stamped down in layers until the level of the 
holes in the walls is reached. Long poles, 6 inches in diameter, are 
then inserted in these holes, and the kiln filled up by layers of coal 
stamped down, and the top is covered by a layer of coal-dust. The. 
end wall is then built up and the poles withdrawn, leaving transverse 
channels in the coal. Before lighting, the vertical chimneys on side 
are closed by a brick, and the draught-holes on the opposite side are 
also closed. Fire is then given to the pile by lighted chips, etc., ap- 
plied at the openings, and from them a current passes out of the chim- 
ney in the opposite side. In 6 or 8 hours the fire will reach the 
other side, when the chimneys on one side are closed and the chim- 
neys on the other side opened, the damper on the horizontal flues 
being also changed at the same time. By this means the current is re- 
versed, and this is repeated every 2 or 3 hours. Different parts of the 
kiln are changed, depending on the working of the operation, the 
