Online Encyclopedia
Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.
SMOKE (from O. Eng. smeocan, to smoke...
Online EncyclopediaEncyclopedia Home :: SIV-SOU
del.icio.us it!
|
See also:SMOKE (from O. Eng. smeocan, to smoke, reek, cf. Dutch See also:meek, Ger. Schmauch, probably allied to Gr. vol9caiv)
, the vapour or volatile See also:matter which escapes from a burning substance during See also:combustion, especially the visible vapour produced by the burning of See also:coal, See also:wood, See also:peat or See also:vegetable substances generally
.
In this See also:article the various legislative and other See also:measures recommended or adopted for the abating of the See also:nuisance caused by the excessive See also:production of See also:smoke are dealt with
.
For smoking of See also:tobacco see TOBACCO and See also:PIPE, and for See also:opium-smoking OPIUM
.
Smoke See also:Abatement.—The nuisance created by coal smoke seems to have been recognized in See also:London since 1306, when a See also:Citizen was tried, condemned and executed for burning " See also:sea See also:cole " in the See also:city of London; but it is only in more See also:modern times that the question has been regarded as one of real practicalimportance
.
In 1785 the first smoke-abating invention was patented by See also: 8," any See also:chimney (not being the chimney of a private dwelling-See also:house) sending forth See also:black smoke in such quantity as to be a nuisance, shall be deemed to be a nuisance liable to be dealt with summarily in manner provided by this act." A further clause provides that for the purposes of sub-sec . 7 the offence is not merely the emission of smoke, but the use of a See also:fire-See also:place or furnace " which does not as far as practicable consume the smoke," and this enables a technical See also:defence to be raised which in practice has been found to destroy the efficacy of sub-sec . 7 . Under sub-sec . 8 the See also:mere fact of sending forth black smoke in such quantity as to be a nuisance is an offence, unless it be emitted from the chimney of a private dwelling-house . This sub-section is therefore always resorted to by sanitary authorities who initiate prosecutions for smoke nuisances . It has been decided that where black smoke issued from a chimney several times a See also:day for varying periods the See also:magistrate was justified in finding that the smoke Issued in " such quantity as to be a nuisance," although it was not shown that any particular See also:person, or See also:property, was injuriously affected thereby (See also:South London Electric See also:Supply See also:Corporation v . Perrin (1901) 2 K.B . 186) . It has also been held that smoke need not be injurious to health in See also:order to be a nuisance (See also:Gaskell v . Bayley, 3o L.T.N.S . 316) .
It therefore follows that the issue of black smoke from See also:ordinary factory chimneys is per se a nuisance
.
From a See also:practical point of view, however, it is often found difficult to identify exactly the See also:colour of the smoke, the See also:appearance of which varies in accordance with the position of the observer, and the See also:light behind or in front of the smoke
.
To aid inspectors various smoke charts and See also:instruments have been devised, none of which is wholly satisfactory
.
The best See also:chart is the Ringlemann smoke See also:scale, made by ruling black lines at right angles on a See also: In the See also:United See also:Kingdom the subject takes an important place in the See also:programme of the Royal Sanitary See also: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 . A knowledge of the nature of coal and of its combustion is essential for an understanding of the smoke problem . For the purposes of this article coals may be classified as smoke-producing or bituminous, and smokeless, the former including all those varieties most commonly used as See also:fuel . The elementary constituents of such coals are See also:carbon (generally about 80%), See also:hydrogen, See also:nitrogen, See also:oxygen and See also:sulphur, and they also contain a varying quantity of earthy impurity or ash . The process which occurs in a coal fire consists of two distinct operations . The first, which requires a comparatively See also:low temperature and is See also:independent of the presence of See also:air, is one of destructive See also:distillation, similar to that which occurs in the retorts of gasworks . It results in the decomposition of the coal, and the formation of the following substances: (r) hydrogen, See also:marsh-See also:gas, carbon monoxide, See also:ethylene, See also:benzene, other See also:hydrocarbons of the See also:paraffin and benzenoid See also:series, See also:water—all of which are either gaseous at the temperature at which they are formed or capable of being converted into gas at some-what higher temperatures, and all of which are combustible except the water; (2) See also:ammonia and other nitrogenous compounds and certain compounds of sulphur, which are also volatile and combustible; (3) See also:coke, which consists of carbon (and ash) and is non-volatile but combustible . It is these products of distillation, not the coal itself, that See also:burn, in the strict sense of the word ; and this second process requires the presence of air and also a much higher temperature than the,first . If the combustion is perfect, the only products are (r) water-vapour, (2) carbon dioxide, (3) nitrogen and (4) sulphur dioxide, the first of which contains all the hydrogen originally See also:present in the coal, the second all the carbon, the See also:fourth all the sulphur, while the nitrogen is liberated as such together with the very much larger volumes of nitrogen derived from the air which has supplied the necessary oxygen . These products are discharged through the chimney . Two things are necessary for ensuring such See also:complete. combustion, viz. an adequate, but not too large, supply of air, properly ad-ministered, and the See also:maintenance of the requisite temperature . In practice, however, these conditions are never perfectly fulfilled, and consequently the combustion of coal is always more or less imperfect and gives rise to a complex mixture of vapours . This mixture.contains not only the combustion products already mentioned, but also the following unburnt or partly burnt distillation products:—(5) hydrogen, (6) hydrocarbons, (7) carbon monoxide, (8) unburnt carbon in a very finely divided state, and also considerable volumes of unused air . Usually the name " smoke " 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 See also: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 See also: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 " smoke " for all the products of imperfect combustion (S to 8) which are avoidable, as contrasted with the necessary and unavoidable ingredients (r to 4) . The problem of smoke abatement is thus seen to resolve itself into the problem of the production of perfect combustion . The See also:solution of this problem would See also:lead to an important saving in fuel . It has been calculated' that at least twice as much coal is used in See also: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 See also:waste could be prevented by improved methods Of combustion . Another See also: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 See also:total quantity is enormous, though the amount contained in any given puff 'of smoke is very small . The " London " or " See also:pea-soup 'r See also:fog would be avoided, not becausefogs 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 2o% of fogs were entirely due to smoke, and that in every See also:case the See also:density and duration of fogs was enormously added to by smoke . It is often stated that these fogs are caused by the smoke that blackens them; but this is an See also:error . The combustion of coal is certainly,responsible for their existence, but it is the sulphur of the coal (oxidized ultimately to sulphuric See also:acid), and not the carbon, that is the active See also:agent . So See also:long as coal is burnt at all this manufacture of sulphuric acid and of fogs must continue; it is not to be got rid of by improved methods of combustion, though the See also:character of the fogs, may be materially improved . The evil effects of See also:town air on plant See also:life and human lungs, also often attributed to preventible smoke, are in like manner due to this non-preventible sulphuric acid . Sixteen million tons of coal are annually used in London for See also:heating purposes, and it has been shown by Dr Rideal that, as the sulphur content of this coal ranges from I to 2 %, there is diffused in the air of the metropolis from See also:half a million to a million tons of sulphuric acid every See also:year . The extent to which smoke and fog affect life and injure property is, perhaps, a matter of See also:opinion . It has, however, been proved that the See also:death-See also:rate enormously expands in foggy See also:weather, and the Hon . Rollo See also:Russell has made a careful calculation showing the extra cost which the smoke nuisance annually imposes upon London . The figure at which he has arrived is £5,470,000, including damage to buildings, fabrics and See also:works of See also:art . The amount of coal consumed each year in the country was calculated by the Royal See also:Commission on coal supplies to amount to 16o,000,000 tons, of which 36,000,000 or 19.2 % are consumed for domestic purposes, and 53,000,000 tons are used in ordinary factories . Thirteen million tons are taken by railways, 15,000,000 by gasworks and 28,000,000 tons by the See also:iron and See also:steel See also:industries . The methods that have' been suggested for the abolition of smoke may be divided into two See also:great classes, viz. those that seek to attain this end by improving the appliances for the burning of bituminous coal, and those that propose to abolish its use and substitute for it some other. See also:kind of fuel . The proposals of the first class may be divided into those applicable to domestic purposes and those applicable to boiler fires and other large-scale operations . Those of the second class may be divided according to the nature of the fuel which they suggest . The innumerable inventions of the first class depend for their success (so far as they are successful) on the See also:attention bestowed on the scientific requisites for complete combustion, viz. a sufficient but not too great supply of air, the thorough admixture of this air with the products of the destructive distillation of the coal, and the maintenance of a high temperature within the fire . In the old and crude methods the facts which most militate against the attainment of these desiderata are—(1) that large masses of fresh fuel are thrown on at the See also:top, which cool down the fire where the highest temperature is required; (2) that. the products of the distillation of this fresh fuel, heated from below, do not get properly mixed with air till they have been See also:drawn up the chimney; (3) that unduly large volumes of See also:cold air are continually being sucked up through the fire, cooling it and carrying its See also:heat away .from where it is wanted, and yet without remedying the second evil . In the See also:imp-oved methods regularity of supply of both fuel and air. is sought so as to maintain a steady See also:evolution of distillation products, a steady temperature, and a steady and complete combustion . In many cases it is sought to warm fresh air before it enters the See also:room by a regenerative See also:system, the. heat being taken from the escaping gases which would otherwise carry it up the chimney; and in some cases the air which feeds the fire is heated in the same why . Tests applied at the South Kensington Exhibition of 1882 and in See also:recent years by the Coal Smoke Abatement Society acting in See also:con-junction with the See also:Office of Works, for domestic grates and stoves, have included a chemical examination of the chimney gases, observations of the " smoke-shade " as indicating the proportion of unburnt carbon, and' a See also:record of the amount of coal burnt, of the rise of temperature produced, of the See also:radiation, and of the amount of heat lost by being carried away through the chimney . Domestic grates and stoves are divided into six classes :—(1) open grates having ordinary bottom grids and upward See also:draught; (2) open grates having solid floors (adapted for " slow combustion ") and upward draught; (3) open grates fed from below, supplied with fresh fuel beneath the incandescent fuel; (4) open grates fed from the back or from the sides or from hoppers; (5) open grates having downward or backward or lateral draught; (6) close stoves . Each of these classes is 'subdivided according as the apparatus is " air-heating or " non-air-heating, i.e. according as an See also:attempt is or is not made to See also:save heat on the regenerative principle . The following conclusions, among others, have been arrived at:—(a) the air-heating principle has not been, applied with success except in class 5; (b) close stoves (class 6) are See also:superior to open grates (ttotal See also:average of classes 1-5) in respect of freedom from smoke and of See also:general heating effect, but they are greatly inferior in radiating See also:power; (c) the "slow-combustion " principle gives a high radiation See also:factor, with a See also:lower See also:consumption of fuel, but is otherwise not successful; (d) the class of air-heating grates with downward, backward, or lateral See also:draughts and with a large See also:surface of fire-See also:brick for radiating heat is, on the whole, most efficient (see HEATING) . In boiler fires, both for locomotives and for fixed appliances, the desiderata are essentially the same as in the case of domestic fires; the principles involved are consequently also the same, though the appliances are necessarily different . These iiriproveinents'mayall classed under one or other of two heads, according as the mode of supplying the fuel or the mode of supplying the air is the subject of the improvement . These two kinds of improvement may of course be combined.' In the old forms of furnace fresh fuel, as it is wanted, is supplied by See also:hand labour, the furnace doors being opened and large quantities of coal thrown in . One result of this is the inrush of great volumes of cold air, which, aided by the equally cold fuel, lowers the general temperature of the furnace . Mechanical stokers meet this difficulty by supplying the coal regularly in small quantities at a See also:time . They may be divided into " coking :' stokers, which deliver the coal at the front and gradually push it backward; " sprinkling " stokers, which scatter it generally over the surface of the grate; and " underfeed " stokers, which raise it from below so that the products of its distillation pass through the already incandescent fuel . The mechanism by which these results are attained is often of a complex nature . It is generally recognized that air cannot be efficiently supplied to the furnace if admitted only in front, and accordingly many plans have been devised for supplying it also at the back and sides . In some cases currents of air are induced by steam-jets; but this See also:plan has not always proved successful . The inventions on the regenerative principle are more generally satisfactory . In them the air, before entering the furnace, is made to circulate through See also:chambers heated externally by the products of combustion, and, having thus acquired a high temperature and absorbed heat that would otherwise have been lost, is admitted through openings at the See also:bridge . Many of these appliances are almost absolutely smokeless, and they are much in use, as they have been shown to effect great See also:economy in coal consumption . It must not be forgotten, however, that with the use of trained stokers a high degree of boiler efficiency is reached by hand-firing alone . Indeed, it has been proved by actual tests that, when pitted against untrained. men, skilled stokers have raised the thermal efficiency of their plant by over 16%, without creating smoke nuisances . In See also:Germany stokers are trained under careful state super-See also:vision, and similar See also:work has been started at the See also:Borough See also:Polytechnic Institute by the London County Council . The See also:advocates of the total or partial disuse of smoke-producing coals are variously in favour of See also:anthracite, coke, electric power, liquid fuel or gas . In some factories, such as malting works, anthracite and other coals containing a high percentage of carbon may be and have long been advantageously used as fuel . They yield a much smaller percentage of distillation products than ordinary coals, and produce no smoke or almost none . But they are difficult to ignite, and in small fires difficult to keep burning without forced draught; they give very little See also:flame, and are comparatively expensive, so that they are under considerable disadvantage as compared with the usual kinds of coal . Many grates and stoves have been devised for burning anthracite for domestic heating, and some of them are successful and econorhicat; but, in view of the national See also:prejudice in favour of a See also:bright and open fire, it is not likely that anthracite will ever replace bituminous coal to any great extent in the See also:British Isles, where the great coal-See also:fields undoubtedly are the natural See also:sources, of fuel . This remark, however, does not apply to the use of coke and of gas, which are themselves made from coal . Coke is produced in large quantities, both for its own See also:sake and as a by-product in the manufacture of gas for See also:lighting purposes, and is largely used in various kinds of furnaces It gives no smoke, but it resembles anthracite also in being but See also:ill adapted for use in open grates on See also:account of the difficulty of ignition and the See also:absence of flame . One of the most notable features of the smoke abatement movement in recent years has been the manufacture of smokeless fuels capable of being readily and satisfactorily burnt in ordinary See also:household grates . The use of such fuels is growing and will, in See also:conjunction with the enormous expansion in the use of gas-cookers and heating appliances, do much to eliminate smoke nuisances from private houses . Over 750,000 gas-cookers: are in use in the metropolis alone, and their aggregate effect in preventing the emission of smoke from See also:kitchen chimneys must be very great . Liquid fuel or natural See also:petroleum, which has come into exceptional prominence during recent years as a beating agent, owes its success to its relatively smokeless combustion and high efficiency . The same applies to gaseous fuel, which includes in addition to ordinary coal gas other mixtures of gases whichburn with a high heating value and with no deleterious vapours or smoke (see 1 CEL: Liquid and Gaseous) . See also:Electricity is now also being largely utilized in factories for power purposes, and is thus bearing its See also:share in solving the problem of smoke abatement . See See also:Official See also:Report of the Smoke Abatement Committee (London; 1882); . W . C . Pppplewell, The Prevention of Smoke (190I); W . See also:Nicholson, Smoke Abatement (1905) ; also the publications of the London Coal Smoke Abatement Society; See also:Booth and Kershaw, Smoke Prevention and Fuel Economy (1904) ; Reports of the See also:Laws in certain See also:Foreign Countries in regard to Emission of Smoke from Chimneys (Foreign Office Return) ,Cd . 2347 (1905) ; LondonFo Inquiry (1901-1902) (Reports to and by the Meteorological Council) . (O . M.; L . W .
|
|
|
[back] SMOHALLA, or SHMOQUALA (i.e. " preacher ") |
[next] SMOLENSK |
Additional information and Comments
There are no comments yet for this article.
Highlight the code below, right click and select "copy." Paste it into a website, email, or other HTML document.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.
Links to articles and home page are encouraged.
