72 Economy of Fuel. (January, 
hopper, and the gases are led off to the blast-heating stoves 
in the usual way. The upper part of the furnace, for 
a depth of 20 feet below the space required for the bell and 
cone, is divided into four compartments by vertical walls 
supported on arches, and radiating from the centre. These 
division walls, by causing additional frictional resistance to 
be opposed to the descent of the materials, relieve the coke 
formed of a portion of its load, but their main object is to 
enable the coking of the coal to be performed in the upper 
part of the furnace. The economic results obtained with 
this furnace have been most satisfactory, and they were thus 
described by Mr. Ferrie himself to the Iron and Steel 
Institute, at their meeting in March, 1871: 
‘“‘In the Lanarkshire district, the quantity of coal 
required in the manufacture of a ton of No. I pig-iron 
ranges from 50 to 52 cwts. in the furnace, whereas, in this 
furnace, a ton of the same quality can be produced with 
32 to 36 cwts., effecting a saving in coal of nearly a ton to 
the ton of iron made. In ores, the saving in this furnace 
will be about 2} cwts. per ton of iron.” 
The quantity of gas drawn off from the furnace is found 
to be greatly in excess of that required for heating the blast 
and raising steam for the blowing engines ; but where works 
for the production of finished iron are annexed to the blast- 
furnaces, ready means may be found for utilising this excess 
of gas. 
The next subject for consideration is the economy of fuel 
hitherto attained in the manufacture of iron and steel. 
Before the introduction of the puddling process, the conver- 
sion of cast-iron into malleable or wrought-iron was always 
effected in a finery or hearth, in which the metal was melted 
in contact with the solid fuel, and so exposed to the highly 
oxidising action of a blast of atmospheric air. Dr. Siemens, 
in a lecture delivered to the operative classes of Bradford, 
on behalf of the British Association, in September last, 
remarked that in the metallurgical furnace there is great 
room for improvement, the actual fuel consumed in heating 
a ton of iron up to the welding point, or in melting a ton of 
steel, being more in excess of the theoretical quantity 
required for those purposes than is the case with regard to 
the production of steam power or to domestic consumption. 
Taking the specific heat of iron at 114, and the welding 
heat at 2700 degrees F., it would require 307 heat units 
to heat 1 lb. of iron. A pound of pure carbon develops 
14,500 units of heat, a pound of common coal 12,000, and 
therefore 1 ton of coal should bring 39 tons of iron up to the 
