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Rh South Kensington. At the close of the exhibition a national smoke abatement institution, with offices in London, was formed.

In the United Kingdom the subject takes an important place in the programme of the Royal Sanitary Institute, whilst the Coal Smoke Abatement Society is devoted to improving the prevailing conditions, especially in the Metropolis, and has organized a number of exhibitions and conferences on the subject. Several smoke abatement committees exist in the provinces.

Usually the name &ldquo;smoke&rdquo; is applied to this vaporous mixture discharged from a chimney only when it contains a sufficient amount of finely divided carbon to render it dark-coloured and distinctly visible. The quantity, however, of this particular ingredient is apt to be overrated. It always bears an extremely small proportion to the vast volumes of water-vapour, carbon dioxide and nitrogen with which it is mixed; it probably never amounts, even in the worst cases, to 3% of the weight of the coal from which it is formed ; and its importance, reckoned in terms of so much fuel wasted, is certainly not greater than that of the unburnt hydrogen and hydrocarbons. It is perhaps best to use the name &ldquo;smoke&rdquo; for all the products of imperfect combustion (5 to 8) which are avoidable, as contrasted with the necessary and unavoidable ingredients (1 to 4). The problem of smoke abatement is thus seen to resolve itself into the problem of the production of perfect combustion.

The solution of this problem would lead to an important saving in fuel. It has been calculated that at least twice as much coal is used in boiler fires and six times as much in domestic fires as is theoretically required for the production of the effects obtained. A considerable portion of this loss is certainly unavoidable; nevertheless, much of this enormous waste could be prevented by improved methods of combustion. Another advantage is the gain in cleanliness and public convenience; not only would there be an end to sooty chimneys, but the atmosphere of towns would no longer be polluted by unburnt carbon, whose total quantity is enormous, though the amount contained in any given puff of smoke is very small. The &ldquo;London&rdquo; or &ldquo;pea-soup&rdquo; fog would be avoided, not because

fogs would become any less frequent than now in London and other large cities, but because they would lose their distinctive grimy opacity.

An investigation of London fogs was made in 1901-1903 by the Meteorological Council with the assistance of the London County Council, from which it appeared that 20% of fogs were entirely due to smoke, and that in every case the density and duration of fogs was enormously added to by smoke.