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26
SMOKE ABATEMENT.
Smoke and fog are to be understood from their chemistry of meteorology respectively.
Given the chemistry of coal and of its combustion products and the chemistry of building
stone and their mortars, certain inferences could easily be made as to possible and probable
damage to buildings. It is noteworthy that such inferences are fully supported by the
chemical facts in analysis of rotted building faces and stone tracery. The relative heats of
combustion in factory and domestic fires, as well as a consideration of their respective types
of coal, whether hard steam or caking coals, would lead to a suggestion that the domestic
chimney might be a large offender in the matter of the soot-tar deposited on our buildings
and occasionally in our nostrils. Again, accurate chemical analysis of the deposits in chimneys
and parts of chimneys, and on buildings, supports the lines of general inference very
fully and with such accuracy as to leave little of our more general observations unexplained.
The floating about in air and the deposit of acid soot or acid tar (the acid being sulphuric
acid) is more than half our difficulty as to damage and discomfort in smoke nuisance,
and the domestic chimney is responsible for more than half this difficulty, even in the manufacturing
towns of the north, and for more than half in the City of London.
The withholding of light by the deposit of soot on the green leaf, which is the food factory
of the plant, has occupied the chemical and biological experimenters, and again the effects
are what might have been expected on general principles. The respiration of the plant is
choked by soot, the green leaves are stunted and fall before their time, partly under the
action of the acid, which is introduced into the myriad mouths of the leaf with the soot.
Not all the acid is in soot, however; much is gaseous in the air, and when dissolved in
rain, falls on herbage and soil; the herbage it destroys in proportion to the quantity of acid
present, the soil it deteriorates by continuance of its mortal influences on the bacteria of
the soil and interference with their particular duties in the economy of the community. Like
soot, the free acid gas in the air can be carried to long distances and then thrown to earth
by rain, but unlike soot, is much more rapidly diffused to larger distances, and, of course,
does not interfere with light.
The detail of all these considerations can be very readily found in Cohen and Ruston's
book, "Smoke. or a Study of Town Air," together with so comparatively slight, but so
sufficiently detailed figures and wealth of correlated experiment by the distinguished chemists
who have applied themselves to the science of coal smoke, as makes the book at once popular
and scientific, a difficult accomplishment, but of immense service to a community, because
numbers must realise and realise accurately, the way in which modification may most
reasonably be attempted, if adequate protection is to be afforded us.
The tree, the blade of grass, the bacillus, are seen to be affected by tar and sulphuric
acid—what of animal life ? Nobody in town but experiences in fog, which, apart from town,
arises, and in the main is dissipated at a touch of sun, a sense of night running into night
without natural light. The fog does not clear, and the less it clears the less its tendency to
clear, because of the circlet of tar which prevents the vaporisation of the mist drop. The
longer the fog hangs, the yellower it becomes, because it blankets the rising smoke and the
more acid become its moist particles. To the sense of depression arising from an absence
of that "pleasant thing it is to behold the day," is added a sense of discomfort to eyes and
nostrils and that irritation of the throat which come from the acid tar, to say nothing of
the grime of it. To get a true view of the above mere personal bodily discomforts of yellow
fog, imagine the individual experience multiplied by millions: that constitutes a mass of
comparative inefficiency and absolute and positive ill worth considerable thinking over
if it can be avoided by taking thought.
Not so striking, but none the less ever present in winter time, even in strong gales
down the wind, is the grey to brown haze which is an effective heat and light screen. This
hangs about on days which people will consider are reasonably fine days with plenty of light,
but is really a dense pall. Coming from Holland towards the Straits of Dover and the
Channel, from fifteen miles distant I have seen this pall streaming off England over the
Channel: ourselves in bright sunshine, with the coast of Belgium and France in bright
visibility at first, and then a gloom of smoke on entering the Channel. I have run up the
East Coast in blazing sun, with a light summer easterly air holding a pall to the west of us
throughout 100 miles of travel. Under that pall the day may be reckoned fine, but it is
a dull day by comparison. This was industrial smoke mainly, for no householder who could
avoid it would have lighted any fire that blazing day.