SMOKE

(Low Germ, smuke.) Smoke has been defined as the visible effluvium or sensible exhalation of any thing burning. The term is commonly applied to those results of the combustion or ignition of pit coal which escape from chimneys, and which constitute a serious and well-known evil and nuisance in large towns, manufacturing districts, and almost every where where large quantities of coal are consumed. Coal is often a very complex substance; but, putting aside its occasional and adventitious ingredients, carbon, hydrogen, nitrogen, and oxygen may be regarded as its ordmary and e ential constituents; and the results of its perfect combustion would therefore be carbonic acid steam and nitrogen. These substances would constitute invisible and incombustible gases and vapour, and would therefore escape from the chimney top, and blend with the atmosphere, without being perceived. But it unfortunately happens that from the way in which coal is burned its combustion is far from being perfect, and that besides the above-mentioned products inflammable gases and vapours, together with large quantities of very finely divided carbon, constituting soot and black and brown smoke, are vomited forth from the chimney shaft, not only contaminating the air, and making all neighbouring objects black and dirty, but also occasioning great lo of fuel; so that the smoke of London is not only a nuisance, but a very expensive one, and ought to be put down by legislative enactments, several of which have been from time to time stiggested, but unfortunately never enforced, and are at this moment a mere dead letter. The neglect which this subject has encountered has arisen chiefly out of the difficulty of enforcing and inculcating rational doctrines upon the subject of combustion, and of getting persons to adopt new systems of construction in regard to furnaces and fire-places, new methods of stoking and managing the fire, and new kinds of fuel; and it is astonishing to observe the obstinacy and per'^■ersene which prevail in these respects amongst the masters as well as the men. There is a not lier cause too, 1124 SMUGGLING. which no doubt has had its influence in retarding tn adoption of means for diminishing the smoke nuisance which is the shoals of quacks and ignorant empyrics am impostors who have embarked in these speculations; si that till stringent and coercive measures are adopted ii regard to it, founded upon scientific and rational princi pies, we must be content to continue breathing a taintei air, which fouls the organs of respiration, encrusts ou buildings, and covers our books, pictures, and every ar tide of furniture with an enamel of soot, and whic! dims the atmosphere to such an extent as materially ti shorten the duration of metropolitan daylight. That all these evils may be got rid of admits of n( doubt, and ultimately with economy and convenience though the first introduction of the remedies will pro bably be attended by many practical difficulties, and con sider able inconvenience and expense. One remedy, anc the most obvious, consists in the substitution of coke anthracite, and certain other smokele fuel, for the bi tuminous and eminently smoke-generating varieties o coal now in common use. Another is, the constructioi of fireplaces and furnaces which shall not indeed bun smoke, but prevent its formation. It must be allowec that there are many practical difficulties in the way, rathe i perhaps of the application than of the invention or per fection of these contrivances; but experience has show i that none of these are of such a nature or magnitudi that they may not be overcome by perseverance and skill They all merge into one common principle, that of mix Ing air with the combustible vapours and gases generatec by the action of heat on pit coal, so that by virtue of a du( supply of oxygen they may be made to burn with flame and become entirely converted into incombustible anc transparent invisible vapours and gases, instead of being as they now are, only partially burned, by which theii carbon is precipitated, and escapes, to get lier with th< other imperfectly consumed matters, into the air. Th( foundation of a practical inquiry into the subject of th< prevention of smoke has been laid by Mr. C. W. Williams of Liverpool {E ays on the Combustion of Coa, and Prevention of Smoke). The theoretical details arc e entially blended with the whole doctrine of heat; bui the investigations which most e entially bear upon then will be found in Sir H. Davy's Researches into the Philosophy of Flame. [s. 1137]