578 



GAS, COAL 



5 or 6 cwts. of Newcastle or Welsh coal every 12 hours, and produces gas at the 

 rate of 9,000 cubic feet per ton of Welsh, and 'lO,000 to 12,000 per ton of Newcastle 

 coal. 



Clegg's revolving Web Retort. This retort, tho invention of Mr. Clegg, sen., makes 

 the nearest approach to a truly philosophical apparatus for tho generation of gas ; in 

 it the coal is exposed to a sudden and uniform heat, in a thin stratum, by which moans 

 the gases are liberated at once, and under the conditions most favourable for the 

 production of a maximum amount of illuminating constituents. Very little tar is 

 produced from this retort. 



Fig. 1037 represents a section of this retort, which is of tho D shape, with a very 

 low and flat arch. It is made of wrought-iron boiler plates riveted together. E is a 



1037 



hopper for holding the coal to be carbonised ; F is a discharging disc ; G is tho retort ; 

 H is a web on to which the coal is discharged by the disc F; 1 1 are revolving drums, 

 carrying the wrought-iron web H ; L L are the flues from a lateral furnace by which 

 the retort is heated ; M is the exit-pipe for the coke, its lower extremity is either closed 

 by an air-tight door, or is made to dip into water. 



All tho coal must be reduced to fragments about tho size of coffee-berries, and a 

 24 hours' charge must be placed at once in the hopper, and secured by a luted cover. 

 The discharging disc has 6 spurs, and is made to revolve uniformly with tho drum 

 below it at the rate of 4 revolutions per hour. The diameter of the hexagonal drums 

 is so regulated that the coal, which falls upon tho web from the discharging disc, will 

 at one revolution have passed the entire length of the retort. The passage through 

 the retort occupies 15 minutes, which is quite sufficient to expel the whole of the pis 

 from the coal. In each revolution of the disc and drum 745 cubic inches of coal (or 

 21 Ibs.) are distributed over a heated surface of 2,016 square inches. 18 cwts. of coal 

 is carbonised in one of these retorts in 24 hours, and the production of gas is equal to 

 12,000 cubic feet per ton of Newcastle coal. Tho quality of the gas is also consider- 

 ably superior to that obtained from the same coal in the ordinary retorts. 



Although the first cost of these retorts and accompanying machinery is considerably 

 greater than that of the retorts in ordinary use, yet the destructible parts can be 

 replaced at about the same cost as that required to replace tho latter. The coke pro- 

 duced is greater in quantity, but inferior in quality, owing to its more minute state of 

 division. The minor advantages attendant upon this form are, that it occupies less 

 space, requires much less manual labour, and enables the retort-house to be kept 

 perfectly clean, wholesome, and free from suffocating vapour. If the principle of this 

 plan could be combined with less complication of details, it would no doubt come into 

 extensive use. 



II. THIB KKFRIGKRATORY APPARATUS. 



From the moment that the gas leaves the retorts it is subjected to cooling influences, 

 which gradually reduce its temperature, until, on leaving the so-called condenser, its 



