86 CONSTRUCTION OF RETORTS; 



retort; H is a web on to which the coal is discharged by the disc F; 

 1 1 are the revolving drums carrying the web H ; K is the furnace ; L L the 

 flues passing under and over the retorts, and finally into the main flue ; M 

 the shoot into which the coke falls ; the end of which may either dip into 

 water or be furnished with a tight door. 



The retort itself, and the chamber in which the drums work, are made of 

 wrought-iron boiler-plates, riveted together so as to be quite gas-tight. The 

 only parts subject to wear and tear are the retort adjoining the flues and the 

 web, both of which are heated ; the latter however never becomes so hot that 

 the shape alters. The action of this arrangement is as follows : 



All the coal must be either ground, or beaten small and screened, so that 

 no lumps remain larger than coffee-berries, and a twenty-four hours' charge 

 must be thrown into the hopper, and secured by a luted cover. The dis- 

 charging-disc, which is nine inches in diameter, with six arms, is made to re- 

 volve uniformly with the drum below it, at the rate of four revolutions an 

 hour ; for this purpose two shafts run the entire length of the retort-beds, on 

 one of which the drums are fixed ; on the other are the discharging-discs, 

 connected at one end by a strap. The diameter of the hexagonal drums is so 

 regulated, that the coal which falls on the web from the discharging-lip will 

 at one revolution have passed the entire length of the retort. Fifteen minutes 

 is quite time enough to convert the coal so distributed into gas. Each link 

 of the web is 14 inches long and 24 inches broad, having a surface of 336 

 square inches, upon which the contents of one partition of the disc will be 

 discharged, viz. a little more than 124 cubic inches of coal in a stratum less 

 than three-eighths of an inch thick. Each successive link receives the same 

 quantity, so that, in one entire revolution of the disc and drum, 74.5 cubic 

 inches of coal (equal to 21 Ibs.) are distributed over a heated surface of 2016 

 square inches, and converted into gas. 



Eighty-four pounds of Wall's-end coal will by this process make 450 cubic 

 feet of gas of the specific gravity '490. It therefore follows, that in 24 hours 

 18 cwt. of coal will be discharged by each retort, making 10,800 cubic feet 

 of gas, equal to 12,000 cubic feet per ton. 



These retorts are considerably more expensive in the first instance than 

 those in general use, but in the end they would be found cheaper. Indeed, 

 the entire arrangement is one of great ceconomy, and by far the most scientific 

 process yet adopted for making coal-gas : it requires no attendance, except 



