COKE MANUFACTURE. 575 
mit the examination of the two flues. The charge having been made, 
and spread on the hearth to a uniform thickness, the doorway is closed 
by a wall of brickwork piled loosely, and a little in front is placed a 
sheet-iron door, which is supported by a horizontal iron bar. The space 
between the wall and plate is then filled with coke dust, so as to seal 
the furnace and prevent the entrance of air. ‘The air necessary for the 
combustion enters the furnace at the rear through the openings in the 
back ; passing through the flues in the chimney it becomes heated, and 
enters the back of the furnace and in the front. The volatile matter 
from the coal is thus burnt in the oven, and escapes by the two openings 
in the rear of the oven, descends and circulates through the flues in the 
bottom, and finally escapes into the chimney. The coal used in Stafford- 
shire in the furnace was the celebrated 10-yard seam, a dry coal, the charge 
consisting of 43 tons of coal and 1 ton of pitch or tar, which are well 
mixed between rollers. The time of the operation is 36 hours, when 
the coke is discharged by an apparatus formed of two cast-iron L-shaped 
plates, which are riveted to two bars of iron. To place them in the 
furnace two flat bars of iron are first put on top of the coke, and upon 
them one of these hoes is shoved to the rear of the furnace; the flat 
bars are then removed and placed on the side of the oven, and the other 
hoe is shoved in in the same manner. The ends of the L-plates fall 
into the vertical space between the rear of the furnace and the coke, 
which has been left by the shrinkage of the coal during the process of 
coking. If there is any difficulty in fastening them in this position 
they are fixed by pokers introduced by the openings in the rear of the 
oven. The pullers are then fastened together by a bar, and the eoke 
pulled out at once by a chain and capstan. The yield of this oven 
when using the materials mentioned is 65 per cent. of coke, which is 
strong and well suited for iron manufacture. 
Of the ovens which are heated by the walls as well as by the 
bottom, the most important and most extendedly employed are the 
rectangular ovens, generally of small width, which as a class are known 
as the Belgian oven, because of the great improvements that have been 
made with them in that country. In speaking of the development of 
this type, M. M. Franquoy* says, that in 1837 Walker obtained a 
patent in England for coke ovens with their bottom and walls heated, 
which were introduced at Seraing in 1856. The first patent for the 
* Progress of Iron Manufacture, Liege, 1861 
