Discovery and Coke is reported to have been an article of commerce in the Chinese province of Hunan some 2,000 years ago. The process seems to have been adapted from the charcoal industry that flourished ex tensively in the Middle Ages. Coke was made in Germany in 1584, at the Hohenbuechen mines in the Harz, by Duke Julius von Braun schweig-Liineberg, and about the same time the master of the Anhalt mint, Daniel Stump felt, made a similar discovery. It appears that in both instances the coke was designed for use as a smokeless fuel, rather than for iron smelting, a use that developed later on. In Eng land a patent for the "de-sulphurizing* of bitu minuous coal was granted to the dean of York in 1590, and in 1619 Dud Dudley, an it onmas ter of Worcestershire, was successful in mak ing coke. Up to this time the coke appears to have been made in the same way as charcoal, namely, by burning in a mound or smeller,* the coal lumps being so piled as to leave draught openings and the whole covered with coal dust or earth. This primitive method gave place to a pit dug in the ground, or to a walled enclo sure, into which the coal was piled, and later into a covered structure known as the °bee-hive oven," so-called from its shape. Such an oven was patented by Sir William St. John and others in England in the year 1620, particular mention being made of the use of the coke so made in manufacturing iron or steel. The bee hive oven did not come into extended use in England until about 1735, when Abraham Darby operated a blast furnace at Colebrook dale, Shropshire, with coke, an example soon followed by others. This innovation was has tened by the increasing scarcity of wood for charcoal, which was the fuel first used for iron smelting. In France, Gabriel Jars, who had visited the English iron-works, is reported to have introduced the use of coke at the iron works in Sainbel. In Germany, Prince Wilhelm Heinrich made coke in closed muffle-ovens of peculiar design, at Sulzbach near Saarbruecken, in 1767, and with it made, it is stated, the first coke-smelted iron on the Continent, at the Fischbacher furnace, near Sulzbach.
Beehive ovens of the English type were built in rows or batteries, both for convenience in operation and to save the heat radiated from one to another, instead of to the atmosphere. Later, modifications were made in the design of the oven, to improve its thermal efficiency and to cheapen the operation. These gave rise to the elongated shape instead of the round or square section, and the retort type of oven was thus gradually developed. The Belgian oven is typical of this form. In it the coking cham ber was from 20 to 30 feet or more in length, 5 or 6 feet high and 18 to 30 inches wide, closed by movable doors at either end, and the coke was removed by a pushing ram which forced out the coked mass as in the present form of by-product oven. This oven was heated by the gas from the coal, which burned in vertical or horizontal flues built into the walls sepa rating adjacent ovens, air being supplied by ducts from the top, and draught from a stack located at one end of a battery of such ovens, connected with them all by an underground flue. Ovens of this general type were constructed by Rcxroth, Copp& and Smet about 1857-60. In
1856, however, Knab was experimenting with a closed retort oven, externally heated, from which he obtained both coke and by-products at Commentry, France. A modification of this oven was built by Carves, and later, by Hues sener, who built a plant at Gelsenkirchen, West phalia, in 1N1. At the same time, an experi mental plant of 10 ovens was built at Watten scheid, Germany, by Otto, the two last men tioned being of the true by-product type. Thus, while the origin of the by-product oven may be conceded to the French experiments of Knab, the development was due to Germany. The Wattenscheid experiments gave rise to the type of oven known as the Otto-Hoffmann, since widely extended, particularly in Germany. The modification of the Knab-Carves oven by Simon, known as the Simon-Carves oven was of the by-product type and was further devel oped by Semet, a Belgian, who in 1881 took out a patent for the oven known as the Semet Solvay.
In the United States the beginning of the development of the coke industry dates about 1810-13. For the same reason that England was forced into its manufacture so was Amer ica. The Pennsylvania Society for the Promo tion of Internal Improvements about this time sent an expert to England to study develop ments in the mother country in the person of W. Strickland. This occurred about 1825.
Mixtures of charcoal and coke were tried, and in 1835 in Pennsylvania a premium of a gold medal was offered to the person who would manufacture in the United States the greatest quantity of iron from the ore during the year, using no other fuel than bituminous coal or coke, the quantity to be not less than . 20 tons. Results were not satisfactory, prob ably due to the poor quality of the coke, pos sibly through selecting a poor coking coal or in the method of blast furnace practice.
The first coke ovens in the Connellsville re gion were built in 1841, but not until 1856 was its use augmented to any great extent; at this time there were established in Pennsylvania alone 21 furnaces in blast on coke. A gradual increase in its successful use was made during the period from the use of Connellsville coke up to the year 1880. At this point the growth was extremely rapid, and its effect of increas ing the iron output of the world of vital import ance.
Methods of Coal was first coked in heaps or mounds in the open air, fol lowing the methods of the charcoal burners, and although resulting in a first-class quality of coke was extremely wasteful. It consisted in arranging rectangular heaps or mounds with longitudinal, transverse and vertical flues to obtain a draft, sufficient wood having been dis tributed in the mass to produce general igni tion. The mound was ignited and the fire al lowed to spread to the whole mass. After the gaseous matters had been expelled, the mound was partially smothered by fine coal dust, the final operation consisting of the application of a small quantity of water, which permeated the whole mass. The application of the water tend ed to develop a coke with few cells and under proper management a low moisture. The yield of coke was in the neighborhood of 55 to 60 per cent, the loss being 40 to 45 per cent of the coal.