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THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



131 



defects llieir starting point. Smoke may therefore be regarded as a mixture 

 of combustible and incombustible gases, in such proportions as to prevent 

 the combustion of the mixture with practical economy." 



Smoke is here defined (o be the product of imperfect combustion ; but 

 what are we to understand by the term " imperfect combustion; " there is 

 no such thing in nature. 'Who ever heard of imperfectly formed carbonic 

 acid, or of steam without a saturating equivalent of oxygen. In fact, the 

 term " imperfect combustion " refers to a period in the history of science 

 when the doctrine of chemical equivalents and the atomic constitution of 

 bodies was still undeveloped, and though justified by common usage, yet 

 language so unprecise is unsuited to philosophical definition, where precision 

 is the great requisite. 



The product of imperfect combustion must, therefore, be understood to 

 mean, the products of perfect combustion, mixed up with what is not the 

 product of combustion at all, or, in other words, a mLxture of combustible 

 and incombustible gases; but how this should ever come to be regarded as 

 a definition of smoke — nay, as being /jar excellence, "the very definition" 

 by which must be tested the merits of all smoke-burning and smoke-pre- 

 venting schemes whatever, is likely to remain a mystery till it please the 

 author of " Thoughts on Steam Locomotion," to elucidate the subject in a 

 second edition. 



That a mixture of carbonic acid gas and olefiant gas, or of coal gas with 

 nitrogen should produce smoke, even though " when taken they be well 

 shaken," is a discovery, which I apprehend may look for its establishment to 

 a period in the prospective history of science, nearly as remote as that to 

 which we are referred in the retrospective, by the terra imperfect com- 

 bustion. And such it seems are the opinions on the constitution of smoke, 

 to which it is alleged Mr. Williams was indebted for the views he has deve- 

 loped in his treatise on the combustion of coal. Let us now attend to the 

 process of its formation, as explained in that treatise. We shall find it to be 

 carbon precipitated from the state of gaseous combination or solution in 

 which it had been held by hydrogen or other gases, forming, it may be, 

 cyanogen or carbonic oxide, but principally the ordinary hydrocarbons. The 

 decomposition of either of the former, or the partial combustion of the latter, 

 may occasion smoke. 



We shall, for the present, confine our attention to the hydrocarbons ; and 

 in the first place, smoke may be produced, if to the gas at a high temperature 

 be presented a certain quantity of oxygen, but not sufficient to saturate both 

 the elements composing the hydrocarbon. In this case the hydrogen, in 

 virtue of its superior afBuity, will combine with its equivalent of oxygen 

 while the carbon will be precipitated, and when cooled below the teuipera- 

 ture of ignition, will assume the form of smoke. Secondly, the reduction of 

 the temperature below that which is required for chemical action, after com- 

 bustion has commenced, is the other principal cause of the formation of 

 smoke. In this case the decomposition of the hydrocarbon will go on, if 

 there be any uncombined oxygen present, steam will be formed, while the 

 carbon being cooled down below the temperature required for combustion, 

 wrill speedily assume the form of smoke. 



The cooling effect of a body of cokl air suddenly admitted into a furnace, 

 must be famihar to all who have studied the phenomena of combustion ; 

 smoke is produced immediately in consequence of the condensation and 

 deposition of the aerial carbon previously held in solution by the hydrogen. 



Let us now consider the arguments by which it is intended to be proved 

 that Mr. Williams' furnace is in reality a smoke-burning and not a smoke- 

 preventing. The substance of the argument is this ; in Mr. Williams' fur- 

 nace carbonic acid is first of all formed, and comes over mingled with the 

 carburetted hydrogen produced by the destructive distillation of the coal. 

 Here, then, is the product of imperfect combustion, a true mixture of com- 

 bustible and incombustible gases, but this is smoke according to the very 

 definition. When, therefore, we effect the combustion of the hydrocarbon 

 in this impure state (or rather in this disreputable company), it seems that 

 we do not burn gas but smoke. In short, the unlucky hydrocarljon is dis- 

 franchised at least, if not decomposed, by its unfortunate proximity to the 

 product of combustion, with which it is more or less contaminated, becomes 

 no longer entitled to the privilege of a combustible gas, but must prolong or 

 terminate its existence as it may, under the ignominious character of smoke. 

 A moment's attention to the actual constitution of smoke as explained above, 

 is snffioient to show the absolute fallacy of the above conclusion. And when 

 we consider that neither of the circumstances which concur iu the formation 

 of smoke have place in tlie argand furnace, viz. either deficiency of oxygen or 

 an injurious reduction of temperature, we shall have no hesitation in according 

 to Mr. Williams the merit of having produced a smoke-preventing furnace. 



To enter further into an elucidation of the principles on which is founded 

 the peculiarly happy and successful practice of Mr. M'illiams, would at this 

 time of day be quite superfluous ; the public are already in possession of full 

 information upon the subject, and anrthing that could be stated here would 

 be only a repetition of what has been better said elsewhere. 



Sir, I am, 



Your's, &c. 

 A. S. 



" MR. CHARLES WYE WILLIAMS, AND HIS BOILER PROJECTS." 



JIr. Editor — The perusal of the article under this head in your last 

 number, has induced me to trouble you with a few remarks upon the subject 

 of combustion. 



It has frequently been a matter of surprise to me, that so much has been 

 written upon this important subject, with so little practical result. It is true 

 we continually hear of experiments, by which some new smoke-consuming 

 theory has been established beyond all question; but unfortunately, no 

 sooner is this new light brought to the test of every-day experience in the 

 stoke-hole, but it is found that, for want of the required degice of combi- 

 nation of either the oxygen, hydrogen, nitrogen, or carbon, that Iji-carburetted 

 hydrogen is generated, and from the absence of sufficient radiation of heat 

 from the brick-work of the furnace, this dense olefiant gas is not decomposed, 

 ergo is not consumed, and consequently it escapes up the chimney, to publish 

 to the world the failure of the experiment. It is vain to attempt any expla 

 nation of the cause which has produced this effect, to the astonished stoker ; 

 all you get from him is a look expressive of unutterable things. 



I can speak feelingly upon this subject, having some little time since had 

 an excellent opportunity of testing the jiractical value of some of the most 

 plausible propositions for economising fuel, .\bout three years since, I was 

 engaged by a Patent Salt Company to give designs for, and to superintend 

 the construction of several of their furnaces, with a view to greater economy 

 in the fuel department, the vital importance of which will be better under- 

 stood, when I inform you that their annual consumption of coals averages 

 25,000 tons. It will not be necessary to go into a detailed account of the 

 efTect of my alterations of the furnaces in question, but simply to confine the 

 following remarks to the general result of the various experiments. I was 

 naturally anxious to avail myself of the assistance of every modern panacea, 

 which had a sufHcient degree of plausibility attached to it ; and consequently 

 jets of steam discharged upon the burning fuel ; cold air admitted in various 

 quantities, in different directions, through apertures of all sorts and figures ; 

 single fire doors, double fire doors, and no fire doors at all ; register doors to 

 the ash pit ; bridges of divers heights and arrangement ; throats of all capa- 

 cities ; dampers in various positions, &c. (but I did not sjjiie my boilers,) 

 were severally and fairly tried under my own superintendence, for months ; 

 and the result of all these experiments was my settled conviction, that how- 

 ever well adapted these modes of combining some gases and decomposing 

 others may be to the lecture-room or laboratory, that in every-day practice 

 they are to a great extent useless, and that the chief desideratum has been 

 lost sight of. This I take to be a regular and constant sujiply of fuel, thinly 

 scattered over the surface of the fire, without the necessity of the frequent 

 opening of the fire door. 



Several attempts have been made to effect this desirable object, but none 

 that I know of are as efficient as I think they may be made. I am at 

 present too much engaged in another department to devote my time to this 

 subject, but 1 think it would repay some of your readers to do so. 



I am, Sir, 

 Si. John's, Worcester, Yours obediently, 



Feb. 9, 1842. E. Leader Williams. 



[The observations we purpose to ofter in answer to the preceding com- 

 munications we shall reserve for our next number. A portion of the letter 

 of Mr. E. Leader Williams, as being irrelevant, we have omitted. AVe have 

 also been obliged to omit a communication from Mr. Smith of Manchester, 

 in support of Mr. Williams' views, but as the points urged by Mr. Siuitli are 

 still more fully developed in the communication of A.S., Mr. Williams' cause 

 can suffer nothing from this omission. .\s journalists we may sometimes be 

 compelled to be severe, but wc trust to be always impartial. — Editor.] 



