WILLIAM SIEMENS, F.R.S. 245 



the waste heat of the flame, and giving it up to the in-coming air 

 us. 



The gas-producer is shown in Plate 41, Fig. 1 ; it is a rectangular 

 irk chamber, one side of which, B, is inclined at an angle of 

 in mi !."> to GO , and is provided with a grate, C, at its foot. The 

 fuel, which may be of any description, such as coal, coke, lignite, 

 peat, or even sawdust, is filled in through a hopper, A, at the top 

 of the incline, and falls in a thick bed upon the grate. Air is 

 admitted at the grate, and in burning, its oxygen unites with the 

 carbon of the fuel, forming carbonic acid gas, which rises slowly 

 through the ignited mass, taking up an additional equivalent of 

 carbon, and thus forming carbonic oxide. The heat thus produced 

 distils off carburetted hydrogen and other gases and vapours from 

 the fuel as it descends gradually towards the grate, and the car- 

 bonic oxide already named diluted by the inert nitrogen of the 

 air and by any small quantity of unreduced carbonic acid, and 

 mixed with these gases and vapours distilled from the raw fuel, is 

 finally led off by the gas flue to the furnace. The ashes and 

 clinkers that accumulate in the grate are removed at intervals of 

 one or two days. 



E is a pipe for the purpose of supplying a little water to the 

 ash pit, to be decomposed as it evaporates and comes in contact 

 with the incandescent fuel, thus forming some hydrogen and 

 carl ionic oxide, which serve to enrich the gas ; G is a small plug 

 hole by which the state of the fire may be inspected, and the fuel 

 moved by a bar if necessary ; and D is a sliding damper by which 

 the gas-producer may be shut off at any time from the flue. 



It is necessary to maintain a slight outward pressure through 

 the whole length of the gas flue leading to the furnaces, in order 

 to prevent the burning of the gas in the flue through the indraught 

 of air at crevices in the brickwork. 



Where the furnaces stand much higher than the gas-producers, 

 the required pressure is at once obtained ; but more frequently 

 the furnaces and gas-producers are placed nearly on the same level, 

 and some special arrangement is necessary to maintain the pressure 

 in the flue. The most simple contrivance for this purpose is the 

 " elevated cooling tube." The hot gas is carried up by a brick 

 stack, H, to a height of eight or ten feet above the top of the gas- 

 producer, and is led through a horizontal sheet-iron cooling tube, 



