528 



NA TURE 



[September 29, 1892 



It was pointed out by the Royal Commissioners in 1871 

 that we cannot suppose ' the production of coal could continue 

 in full operation until the last remnant was used, and then sudden- 

 ly cease. In reality a period of scarcity and dearness would first 

 be reached. This would diminish consumption and prolong 

 duration ; but only by checking the prosperity of the 

 <:ountry.' .... 'Much of the coal included in the re- 

 turns could never be worked except under conditions 

 of scarcity and high prices. A time must even be an- 

 ticipated when it will be more economical to import part 

 of our coal than to raise the whole of it from our residual coal- 

 beds. ' As the area of coal-bearing strata in North America is 

 fully seventy times greater than ours, it is easy to see where our 

 future supplies must come from. The rate of increase in the use 

 of coal has been greater than the Commissioners anticipated in 

 1 87 1, and Mr. T. Foster Brown, C.E., President of Section F 

 of the British Association at Cardiff last year, has placed on 

 record his opinion that at the end of only fifty years from the 

 present time the increased cost of coal will be severely felt. 

 Pessimism is never pleasant ; nevertheless we cannot afford to 

 ignore reasonable inferences from fairly ascertained facts. 



I apprehend that there are few ordinary consumers likely to 

 be influenced in avoiding waste by the knowledge that we are 

 within measurable distance of the end of our store of British 

 coal, as that calamity may still be some generations off. But 

 the case is very different with large consumers ; the inevitable, 

 if gradual, increase in the cost of coal has effectually arrested 

 the attention of those directly concerned in our great industries 

 or anxious for the maintenance of that manufacturing supremacy 

 to which this country chiefly owes its wealth and power. Keen 

 international competition in trade has quickened the effort to 

 get the utmost work out of fuel, and therefore to diminish 

 waste. 



No such considerations have, however, produced any effect on 

 the domestic conscience. A spasmodic increase in cost of coal 

 stimulates the use of various economical devices which are 

 almost wholly given up when prices fall back nearly to their 

 former level. A small residual effect is left, which, though 

 slight, is on the right side. But that economy in the domestic 

 use of coal which could not be effected by a patriotic desire to 

 avoid the too rapid exhaustion of our coal beds, or by a fear of 

 permanently dear coal, is likely to be brought about by the 

 growing nuisance of large towns, namely, fog, for whose increase 

 our ' hearths and homes ' are in a greater degree responsible 

 than the much abused factory chimneys. The primary con- 

 sideration in seeking to cope with the fog demon no doubt is to 

 avoid the production of solid particles during the combus- 

 tion of any fuel we may use, hence that method which 

 avoids the formation of smoke at any time, and is both 

 more convenient and economical, must ultimately ' hold 

 the field.' As you well know, various suggestions have 

 been made for the purpose of avoiding the production of smoke, 

 and it has even been proposed that the use of non-flaming coal 

 should be made compulsory in all large towns, notwithstanding 

 the difficulties known to attend the combustion of anthracite or 

 similar substances in open grates. But even if the fog demon 

 <;ould be satisfactorily exorcised by such means, the fact would 

 remain that the combustion of any solid fuel in an open grate 

 is a most wasteful proceeding. On the other hand, closed grates 

 or stoves have not been popular in these countries. How, then, 

 can we combine economy in the use of coal with smokeless com- 

 bustion and domestic convenience ? The answer is sufficiently 

 obvious — we must more or less completely gasify the coal prior 

 to i*s complete combustion. 



The late Sir William Siemens showed us long ago how to 

 convert coal completely into gas by means of his great 'pro- 

 ducer' furnaces, and demonstrated the applicability of the 

 comparatively pcor 'producer' gas to operations requiring 

 very high temperatures as well as to the minor work of steam 

 raising. Siemens showed that when so used one ton of coal 

 can perform as much work as 1 7 tons directly burned. In such 

 comparisons the ' producer ' gas was, of course, burned at a 

 short distance from its source and under the regenerative system. 

 This mode of using coal seems to be the most economical of 

 which we have practical experience ; but the gas which is pro- 

 duced seldom contains less than 65 per cent, of useless nitrogen, 

 and therefore is not rich enough in combustible matter for general 

 •distribution. 



The Wilson method of gasifying coal and that employed 

 fcy the Leeds forge, permit the production of a richer gas. 



NO. II 96, VOL. 46] 



The Wilson process involves the formation of a certain 

 proportion of 'producer' gas in raising the tempeiature 

 of the coal up to the point at which it can decompose steam, 

 and then affoids a mixture of carbon monoxide and hydrogen, 

 or so-called 'water-gas.' The former can be used for steam 

 raising or furnace work in the immediate vicinity of the pro- 

 ducer, while the water-gas can be transmitted through mains as 

 readily as ordinary town gas, and loses nothing by carriage save 

 its initial heat. Thus one general method affords two qualities 

 of fuel and gasifies the coal in an economical manner. 



Whether by the Siemens method in its modern form or by 

 the more or less complete conversion into rich water-gas, a great 

 saving in coal can now be secured in almost all large operations 

 requiring the command of high temperatures ; and the use of 

 such gaseous fuel is so steadily extending that we may expect in 

 the near future to reach the maximum practicable economy of 

 coal in our greater industries and of smoke abatement as well. 



Between the complete conversion of coal into gas and the very 

 partial process included in the production of ordinary illumina- 

 ting gas is a wide gap which needs to be bridged over in the 

 interests of the small manufacturer and the domestic consumer 

 alike before we can secure that economy in the use of coal which 

 we know to be necessary. For it must be granted at once that 

 our ordinary i6-candle illuminating gas is seldom an economical 

 fuel at an average price of 3^. per looo cubic feet, though it is 

 capable of being so used as to effect distinct saving under special 

 circumstances. As an example of its economical use, even near 

 the price stated, I may cite the case of the kitchen of St. John's 

 College, Cambridge, where gas and steam have been substituted 

 for coal, and an annual saving effected amounting to about ^80. 

 But in establishments which cannot be systematically conducted 

 coal-gas at 35. is too expensive a fuel. Several solutions of this 

 important practical problem have been proposed ; one group of 

 suggestions involving the supply of two distinct gases, an 

 illuminating and a fuel-gas, and therefore requiring two sets of 

 street mains ; but the progress of electric lighting is so rapid 

 that gas companies would not be justified in outlay of capital on 

 a second set of mains. Another proposal is to supply one gas 

 of high calorific value but low illuminating power at a cheap 

 rate, and this gas, when Used for lighting, to be charged at the 

 point of consumption with vapours of suitable hydrocarbides. 

 But the true solution involves a compromise much on the lines 

 along which gas managers are at present apparently working. 



You are aware that the average produce of i6-candle gas per 

 ton of coal is about 9500 cubic feet. By the introduction of 

 steam to a small extent the volume of gas can be materially in- 

 creased, but at the expense of the illuminating power. In order 

 to compensate for this loss, rock or other oils are injected along 

 with the steam, and the illuminating power is maintained. An 

 objection to this practice is that carbon monoxide is present 

 in such gas, but it is also found in many samples of 

 ordinary coal-gas, and provided the gas has a strong and cha- 

 racteristic odour, so that its escape can be readily detected, no 

 risk need attend its use. The supply of the richer bituminous 

 coals is steadily diminishing, hence the practice must grow of 

 supplying a modified water-gas instead of coal-gas as we have 

 hitherto known it. Better far, in the interests of producer and 

 consumer alike, that the inevitable change in the character of the 

 gas manufacture should be carried out with the full knowledije 

 and assent of the public after due Parliamentary inquiry, and in 

 such a manner as to secure the maximum advantage without 

 undue interference with the great monopolies enjoyed by the 

 gas companies. So many satisfactory methods are known by 

 which the illuminating power of a gas can be increased at or 

 near the burner, and gas as an illuminant is moreover being so 

 certainly displaced by the electric light that the objections 

 hitherto urged against the supply of gas of high calorific value 

 but low illuminating power have almost ceased to have any 

 practical force. On the other hand, the supply of a cheap gas 

 of the kind I refer to would prove a great boon to small manu- 

 facturers as well as to the domestic consumer, and competent 

 gas 'engineers inform me that no real difficulties lie in the way. 



The rapid extension of electric lighting in our large towns 

 brings us within measurable distance of some such sweeping 

 change in the character of gas used, in its applications, and 

 in its mode of employment, while the existing mains would 

 serve for its conveyance, and comparatively trifling alterations 

 in our domestic appliances would only be necessary. 



It is in this direction, then, that the best prospect of solving 

 a considerable part of the smoke fog difficulty seems to lie, and 



