232 
THE SMOKE ABATEMENT EXHIBITION. 
some of these constituents, notably sulphur, may become very 
important from the deleterious influence which they exert on the 
respiratory organs. 
Thus we are able to infer the conditions under which fuel 
will be so burned as to give no smoke. 
If we can get a fuel which is almost entirely composed of 
carbon, such as anthracite coal is, we shall have no smoke. But 
there is a difficulty in lighting a fire with this coal, and if it is 
heated too quickly it breaks up into small pieces, which fall 
through the grate bars and are lost, therefore it has to be put 
into the fire gradually, so that it becomes slowly warmed before 
it is ignited. \' hen dry, this coal gives no flame, but when 
moistened it gives yellowish flames. Thus we see that if a 
satisfactory means of burning anthracite coal could be devised, 
and, what is even more difficult, if people could be persuaded 
to use it, there wmuld be no smoke produced from it. 
But if bituminous coals are employed, smoke must be pro- 
duced, and having been produced, if it is not to leave the 
chimney, it must in some way be consumed. It may be con- 
sumed either by leading it through the fire, so that by passing 
again through the ignited mass, the smoke may be burned, or it 
may be burned by mixing with it a proper amount of air, which, 
in order not to cool it below the temperature of ignition, should, 
be previously heated. 
These, then, are the only theoretical conditions required for 
the combustion of smoke. Let us now go to the Exhibition to 
find out in what way these principles have been practically 
applied. 
The exhibits at South Kensington may be divided into eight 
classes, viz., domestic grates, stoves, furnaces with mechanical 
feeding arrangements, multiple-stage furnaces, firedoors and bars 
of various kinds, various devices for consuming smoke, apparatus 
in w hich gas is consumed, including gas engines and gas burners. 
