ON FOG. 
39 
high, temperature to secure the required end. Automatic or 
closed stoves of all kinds seem out of the question, and, indeed, 
make as much smoke as an open grate ; only it is not seen till 
it escapes at the chimney- top. 
Another, and far more hopeful scheme, is advocated by a 
writer in the Engineer , a class paper already referred to, and 
which is specially qualified to speak on such a subject. It has the 
advantage that it 4 would leave us our open fires and our coal 
just as they are. It consists in depriving the smoke of its sus- 
pended carbon. To a large extent this is done for us already 
by our chimneys. The sweep every year takes away enough 
soot to render London fogs — were it found in them — ten times 
worse than they are. There is every reason to believe that the 
partial or total cleaning of household smoke is not at all beyond 
the reach of the inventor who will approach the subject with 
an intelligent perception of facts. Why is it that much of the 
soot is now deposited in our chimneys P The answer is that 
the particles come in contact with the sides, lose their velocity, 
and fall, or adhere to the bricks. It is well known that 
wherever an eddy can he formed in a chimney there will soot 
he deposited in quantity. Soot is delivered from the top of a 
chimney solely because the particles are very small, so small 
that their superficies is enormous as compared with their 
solidity. Consequently they are when set afloat in a current of 
air easily borne up and carried to the top of the chimney. 
Once there the current is gone, and they fall by their own 
gravity as a shower of “blacks.” How, if the velocity is once 
taken out of them and they are not permitted to be caught up 
by a current again, we are done with them as far as smoke is 
concerned. To get rid of them we must do just what is done 
in getting moisture out of steam — permit the current to strike 
a series of flat surfaces from which it is deflected. These sur- 
faces, so to speak, “ knock ” the water out of steam. The prin- 
ciple has been very elegantly employed in a gas purifier which 
we illustrated in our pages not long since. The object in view 
is to get rid of carbon in suspension in the gas.’ That such a 
plan could be rendered efficient ‘ is certain, but that trouble and 
expense would be incurred must not be denied. Its great claim 
to popular support would consist in the fact that its adoption 
would interfere with no popular prejudice in favour of open 
fires and their existing management. * 
