CONSTRUCTION OF RETORTS. 79 



I subjoin a letter which I have received from Mr. Brunton, fully explaining 



his views on the subject. 



"West Bromwich Gas-Works, 5th Nov. 1840. 



" DEAR SIR, Agreeably to your request I herewith send you a statement of my 

 reasons for adopting the form and principle of my patent retort ; in the first place, the 

 particular form and arrangement, and, secondly, wherein I am induced to expect a 

 greater quantity of gas from the coals so introduced, carbonized and discharged. 



" It will be seen by reference to the drawings that the arrangements are so widely dif- 

 ferent from the ordinary form of retort, that scarcely any comparison exists. The ex- 

 ternal appearance does not present so wide a contrast as in the mode of working them, 

 which by considerable experience has proved satisfactory not to me alone, but to those 

 who have watched and calculated their operation, and found the saving to be 30 per 

 cent, of labour and tools, with 35 per cent, more gas from the same quantity of coals. 



"In describing the apparatus and its working, it is necessary to state that to the 

 mouth-piece of my retorts is fixed a slide-valve C, according to the drawing, through 

 which the coal is introduced into the retort, over which, upon a frame, is placed a hopper 

 B, capable of holding one charge of coal, say from 20 to 28 pounds, so that when the 

 valve is withdrawn the charge drops into that part of the mouth-piece in front of the 

 piston ; the valve is again closed ; this part of the operation never exceeds more than six 

 seconds of time. The object of the piston is to push forward the coal which has fallen 

 into the retort to make room for another charge. The piston is propelled forward by a 

 double-threaded screw, which is worked through a stuffing-box at the end in the middle 

 of the lid to prevent the escape of gas. 



" The retort is charged once every hour, or oftener, according to the quality of the coals 

 that are used and the heat of the retort. This is one feature in the improvement of these 

 retorts, that by varying the times of charging, with the other necessary duties requisite, 

 you may increase or decrease the quality of the gas produced to any density or illu- 

 minating power, with less labour and more practical correctness than by any other 

 retort in use. 



" It will be observed, that in the operation of forcing forward a charge of coal, a quan- 

 tity of coke will be discharged into the water-cistern at the wider end of the retort, to 

 which is attached a close shoot H, through which the coke drops into the cistern, and is 

 taken out of the water by a rake or shovel, or endless chain, with a little contrivance. 



" Being in the habit of using South's Staffordshire coals, which swell in a certain ratio 

 during the process of carbonization, and agreeably to the proportion of their enlargement, 

 I have increased the area of my retort, that no obstruction should take place in the pas- 

 sage of the coke. 



" I would here observe, that it is necessary to the correct working of these retorts that 

 the quality of coal with respect to its enlargement should be considered in making the 

 retorts, to secure the easy discharge of the coke and prevent breakage, etc. 



