COAL-TAR 



299 



and convenience of charging. Each oven is a brick structure 

 lined with firebrick. There is an opening below by which the 

 coal is charged into the oven and by which the coke when pro- 

 duced is withdrawn. The oven is filled up to the shoulder, giving 

 a layer of coal about five feet thick, and the combustion is 

 started at the top and proceeds downwards till the whole is 

 deprived of volatile matter and the luminosity of the flame at 

 the top practically ceases. During the burning the admission of 

 air through the door is regulated by a damper or a movable brick. 

 When the operation is over the coke is withdrawn and quenched 

 with water. The oven while still hot receives a fresh charge of 

 coal. This process yields a quantity of coke amounting to about 



FIG. 99. THE BEEHIVE COKE OVKX. 



60 per cent of the coal, but while the coke is hard, lustrous, and 

 eminently fitted for use in the blast-furnace or foundry the 30 

 or more per cent of the volatile products are all lost. 



The importance of saving the tar and the ammonia which are 

 given off by coal, when heated, together with a large quantity of 

 inflammable gas has led to an immense amount of invention, and 

 an almost innumerable variety of ovens have been devised with 

 the object of recovering and utilising these by-products. One of 

 the first contrivances introduced was the coke oven known as 

 Jameson's. This was shaped like a beehive, but the floor sloping 

 forward was perforated with holes which opened into pipes 

 underneath. These communicated with a large horizontal 

 main which ran along the front of a series of ovens and in which 

 tar and ammoniacal water collected. The gas was drawn forward 

 by a pump and delivered into a gas-holder. The more modern 



