WII.UAM STEVENS, F.R.S. 193 



I'.Tno Falir.), the number of heat units alworbed by the iron does 

 ii"t exceed, according to the best authorities, about 900, which 



would be producible with about -- - = 0*075 Ib. of coal. 



1ZUUO 



Iii an ordinary furnace, the coal burned to heat a ton of iron to 

 rlic wilding point amounts to about 12 cwts., or '6 Ib. of coal per 

 pound of iron, making the actual consumption eight times that 

 indicated by theory. 



A^ain, in. melting a ton of steel in pots the number of heat 

 units actually absorbed by the metal may be roughly estimated at 

 about 1,800 units per pound weight, whereas the fuel actually 

 consumed to melt a ton of mild steel in pots amounts to 3 tons in 

 the dense form of coke, or 3 x 12,000 = 36,000 units per pound of 

 steel melted. 



Here we find that the actual consumption exceeds the theoretical 

 in the ratio of 20 : 1, without taking into consideration the loss 

 of effect which had already taken place in converting the coal into 

 coke. 



Here is a field for effecting a saving in fuel which has particu- 

 larly occupied my attention for a number of years, and, with your 

 permission, I will give you a description of the means resorted to 

 by myself and my brother, Frederick Siemens, who is associated 

 with me in these improvements, to accomplish more economical 

 results. 



These consist in the combination of an apparatus for the entire 

 conversion of fuel into unrefined gas, with a furnace constructed 

 upon the regenerative principle, suitable for the combustion of 

 such gaseous fuel. 



The gas-producer, Fig. 1, Plate 8, is a rectangular fire-brick 

 chamber, one side, B, inclined at an angle of from 45 to 60, and 

 provided with a grate, C, at the foot, through which passes a regulated 

 quantity of air. Fuel is tilled in through a hopper, A, at the top 

 of the incline, and carbonic acid gas is the first result of com- 

 bustion taking place at the foot of the producers. The carbonic 

 acid gas thus produced, in passing through the thick stratum of 

 incandescent fuel above, is converted into carbonic oxide, while 

 some of the surplus heat distils the hydrocarbons in the fuel on 

 the incline. Below the grate water is supplied in limited quantity, 

 E, which is decomposed into its elements by heat which would 



Vol.. III. O 



