S/K WILLIAM SIEMENS, F.R.S. 87 



water trough D, filled with water up to a constant level from the 

 small feeding cistern E, supplied by a water pipe with a ball tap. 

 Tlii- large opening under the water trough is convenient for draw- 

 ing out clinkers, which generally collect at that point. The small 

 stoppered holes F F at the front and G- G at the top of the pro- 

 ducer are provided to allow of putting in an iron bar occasionally 

 to break up the mass of fuel and detach clinkers from the side 

 walls. Each producer is made large enough to hold about 10 tons 

 of fuel in a low incandescent state, and is capable of converting 

 about 2 tons of it daily into a combustible gas, which passes off 

 through the opening H into the main gas flue leading to the 

 furnaces. 



The action of the gas producer in working is as follows : the 

 fuel descending slowly on the solid portion B of the inclined plane, 

 Plate 7, becomes heated and parts with its volatile constituents, 

 the hydro-carbon gases, water, ammonia, and some carbonic acid, 

 which are the same as would be evolved from it in a gas retort. 

 There now remains from 60 to 70 per cent, of purely carbonaceous 

 matter to be disposed of, which is accomplished by the slow current 

 of air entering through the grate C, producing regular combustion 

 immediately upon the grate ; but the carbonic acid thereby pro- 

 duced, having to pass slowly on through a layer of incandescent 

 fuel from 3 to 4 feet thick, takes up another equivalent of carbon, 

 and the carbonic oxide thus formed passes ofi' with the other 

 combustible gases to the furnace. For every cubic foot of com- 

 bustible carbonic oxide thus produced, taking the atmosphere to 

 consist of th part by volume of oxygen and ths of nitrogen, two 

 cubic feet of incombustible nitrogen pass also through the grate, 

 tending greatly to diminish the richness or heating power of the 

 gas. All the carbonaceous portion of the fuel is not however 

 volatilised on such disadvantageous terms : for the water trough 

 D at the foot of the grate, absorbing the spare heat from the fire, 

 emits steam through the small holes I under the lid ; and each 

 cubic foot of steam in traversing the layer of from 3 to 4 feet of 

 incandescent fuel is decomposed into a mixture consisting of one 

 cubic foot of hydrogen and nearly an equal volume of carbonic 

 oxide, with a variable small proportion of carbonic acid. Thus 

 one cubic foot of steam yields as much inflammable gas as five 

 cubic feet of atmospheric air ; but the one operation is dependent 



