290 



NATURE 



[December 29, 1910 



SMOKE AND ITS PREVENTION.' 



T TNDOUBTEDLY the most important question of the 

 ^ day from the sanitary and artistic point of view is 

 how best to combat the smoke nuisance, which, like a 

 cumulative poison, is slowly but surely saturating our 

 lives and homes with its filthy dregs, and is at the same 

 time like a cancer depleting and destroying our natural 

 strength by the waste of our already rapidly diminishing 

 fuel supplies. 



When, in the thirteenth century, bituminous coal was 

 first used for fuel purposes, the smoke to which it gave 

 rise roused such indignation amongst the public that a 

 decree was passed in 1306 forbidding its use ; but fuel 

 had to be found, and the suppfy of timber proving in- 

 sufficient, once more attempts were made to introduce it, 

 but again public opinion led to its banishment in the 

 reign of Queen Elizabeth. The third attempt, however, 

 to bring it into use proved successful, and slowly the 

 consumption increased, until the last century saw coal 

 firmly established, not only as a fuel for domestic con- 

 sumption, but also as our great source of power, and it 

 was the possession of great stores of the fuel that gave 

 England her commercial supremacy. 



The smoke from the few chimneys where coal was used 

 by our forefathers, and which so shocked the sense of the 

 observers of that day as to lead to its use being banned, 

 was an absolutely negligible quantity as compared with 

 the smoke belched forth into the air in any of the large 

 cities of to-day, and the effect upon our climate, our 

 health, and our buildings has so steadily risen with the 

 increase in consumption that it is no exaggeration to 

 speak of it as a cumulative poison. 



It was only in the latter half of the last century that 

 the cumulative effect of smoke began to make itself 

 appreciable, and the 'eighties and 'nineties were marked 

 by a diminution in the hours of sunshine in our big cities 

 and by fogs of remarkable density and lasting power ; but 

 such legislation as was enacted and the efforts of those 

 interested in smoke abatement have apparently had some 

 slight influence in a reduction of the plague, and certainly 

 during the past ten years the fogs have not been of the 

 same density or so frequent as in the preceding twenty 

 or thirty years, but how far this has been due to efforts 

 at smoke abatement and how far to meteorological con- 

 ditions I, at any rate, am unable to say. It is an abso- 

 lute fact that even if a certain amount of work has been 

 done, so much still remains to do that the subject is as 

 important now as it was ten years ago, and my desire 

 this evening is to attack the subject of smoke from the 

 more chemical and physical side of its production, and to 

 review those methods which are practically possible for 

 its prevention. 



It must be borne in mind that the smoke question not 

 only affects the well-being of the country, but also implies 

 a waste of fuel so great that with the problem of failing 

 coal supplies looming on the horizon it behoves us to 

 make a national matter of it, not only from a hygienic, 

 but also from an economic point of view. Indeed, the 

 whole question of fuel economy is so closely allied to the 

 problem of smoke prevention that it is impossible to con- 

 sider the one without the other, and if only rational 

 methods of heat production were adopted, both economy 

 of fuel and cleansing of the atmosphere would follow. 



The principal source of the cloud which hangs over our 

 big towns, cutting off the direct rays of the sun and 

 ruining health, varies with the locality. In the south of 

 England it is the domestic grate using bituminous fuel 

 which is responsible for the major portion of this pollu- 

 tion of the atmosphere, whilst further north, in the great 

 manufacturing centres, it is the factory shafts which emit 

 the pall of black smoke that aids in shortening life and 

 killing vegetation, and which begrimes and finally helps 

 to destroy our public buildings. 



Many estimates of the relative amount of pollution due 

 to manufactories and to the domestic grate have been 

 made, but as the question of what is the ratio of smoke 

 production from the various sources varies enormously 

 with the locality, no very satisfactory conclusion has been 

 arrived at. 



^ A lecture delivered at the London Institution on December 8 by Prof. 

 Vivian B. Lewes. 



With regard to London, Dr. Shaw's estimate that 70 pe^ 

 cent, of the smoke is due to the domestic fire would probi 

 ably be about correct, but in Shellield or Birmingham th(j 

 figures would most likely be reversed. But it is a certain 

 fact that domestic smoke is produced throughout the whol^ 

 length and breadth of the land, whereas the factor* 

 chimney concentrates its attention on the more limite 

 area of the manufacturing districts. , 



Although it is diflkult to gain any idea of the ratio ol 

 blame to be given to the two greatest sources of smok^ 

 production at any one spot, yet it is easy to obtain ai 

 insight as to the relative total amount of smoke so pro3 

 duced from the uses to which our coal is put, and the! 

 Royal Commission on Coal Supplies arrived at the con-3 

 elusion that, of the 167 million tons of coal burnt in thii 

 country in 1903, 36 millions were used for domestic hear 

 ing, whilst, after deducting the coal used for gas making, I 

 would probably be near the truth to say that the domestU 

 use of bituminous coal is responsible for one quarter <^ 

 the smoke pollution of the country, the responsibility fc 

 the remainder being split up amongst the various mam 

 factures and railways. 



Practically all the advances of late years have been . 

 fuel consumption on the large scale, and the improyfl^ 

 ments brought about by stoking machinery and attentioi 

 to air supply have been great, whilst some of the largea 

 manufactures have demonstrated, not only the ease ol 

 obtaining smokeless factory shafts, but also the economj 

 that accompanies them. . 



Little, however, has been done to improve the condij 

 tions of fuel consumption in the household, and in spit^ 

 of the fact that the use of bituminous fuel in the domestic 

 grate has been condemned for the part it has played ii^ 

 the pollution of the atmosphere from the earliest years 

 of the fourteenth century to the present day, the ideas thai 

 exist as to its composition and method of production are 

 still very vague, and it is this side of the question witM 

 which 1 now desire to deal. In an ordinary open fire 

 radiant heat given by the incandescent fuel and heated 

 grate warms the room, and although it is. undoubtedly 

 a wasteful method, owing to the largest proportion of the 

 heat escaping up the chimney with the products of com- 

 plete and incomplete combustion, yet it is so superior 

 from the hygienic point of view, and so much more corn- 

 fortable than anv other method of heating, that it still 

 holds the premier position in spite of the economic 

 advantages of central heating systems or slow combustion 

 stoves. 



The production of smoke from the ordinary open grate 

 using bituminous coal means a waste of fuel, but although 

 this loss assumes grave proportions when the number of 

 fires is taken into consideration, it is small as compared 

 with the other losses due to actions taking place in the 

 fire itself and the loss of heat escaping up the chimney. 

 When bituminous coal is fed on to the burning fire, the 

 action which takes place on the newly added portion 

 closely follow the lines of action occurring during the dis- 

 tillation of coal, and it is during this period that a very 

 large proportion of the heat units in the coal are lost, 

 owing to the amount taken up in decomposing the coal 

 and converting the volatile portions into vapours and 

 gases. During this period the coal, heated by the fire 

 from below and comparatively cool above, distils off tar 

 vapours, coal gas, and steam in proportions which vary 

 with the temperature. In the early stages, the surface 

 of the fuel being too cool to lead to their ignition, they 

 escape as vapours up the chimney, mingled with an 

 amount of air which is dependent upon the draught of 

 the chimney, and ranges from eight to thirty thousand 

 cubic feet per hour. In an ordinary flue the composition 

 of the escaping products may be taken as approaching to 

 the following analysis : — 



Per cent. 



Carbon dioxide 0'70 



Methane 0-36 



Hydrogen 029 



Carbon monoxide ^'^^ 



Oxygen ^9-85 



Nitrogen 7979 



and these gases, together with water vapour, escape up 

 the chimney. 



NO. 2148, VOL. 85] 



