576 GEOLOGY OF OHIO. 
introduction of air was also patented in England in 1837. Although 
this was introduced in France and Belgium they were unsuccessful from 
the manner of introducing the air, and in 1844 Dulait, of Charleroi, 
Belgium, invented an oven in which the air was introduced in small 
currents into the encircling flues, which was very successful, and is the 
plan now adopted in many coke ovens in Belgium. The inducing 
circumstances in the introduction of these furnaces is stated by Mr. 
Aug. Sillers, of the School of Mines at Liege * to be, that in 1852 “the 
extraction of bituminous coal necessary for the manufacture of coke by 
the means then employed became insufficient in the Charleroi district, 
and the price increased to such a figure as to threaten serious injury to 
the iron trade. It was therefore found necessary to economize fuel, and 
to find means for manufacturing coke out of semi-bituminous (dry) coal, 
which circumstances were the means of bringing numerous varieties of 
ovens under notice of the industrial community.” Shortly after the 
same circumstances visited other contizental regions, which with their 
great success, caused their rapid extension. ‘The demands of the rail- 
ways, about this time on the Continent, requiring the production of a 
purer and better coke, and its manufacture from inferior and often very 
dry coals, stimulated the improvements in coal washing and coking, for 
which we are largely indebted to French and Belgian experience. 
Difference of size, arrangement of flues, and other modifications 
have multiplied the number of this type of ovens, and they are now 
very largely used on the Continent of Europe, but in England, from 
the nature of the coal, lack of appreciation, etc., though the type 
originated in that country, they are used to but a small extent, and have 
not supplanted the old bee-hive form of oven. 
In the United States their good results in quantity and quality of 
coke has induced their use for not only the drier and less strong coals, 
but also for the better and stronger coking coals. Ovens of this type 
are now used in many places in the Allegheny and Missouri coal basins, 
and their employment is rapidly extending. In the treatment of the 
coals of the Missouri basin, we have, however, probably to witness 
their greatest efficiency. 
* Belgian Coke Manufacture, Jul. Iron and Steel Institute, vol. 1, 1873. 
