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You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: A Practical Treatise on Gas-light + Exhibiting a Summary Description of the Apparatus and + Machinery Best Calculated for Illuminating Streets, Houses, + and Manufactories, with Carburetted Hydrogen, or Coal-Gas, + with Remarks on the Utility, Safety, and General Nature + of this new Branch of Civil Economy. + +Author: Fredrick Accum + +Release Date: January 2, 2014 [EBook #44567] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK A PRACTICAL TREATISE ON GAS-LIGHT *** + + + + +Produced by Chris Curnow, Harry Lamé and the Online +Distributed Proofreading Team at http://www.pgdp.net (This +file was produced from images generously made available +by The Internet Archive) + + + + + + + +Transcriber's notes + +Italics in the original work are transcribed between _underscores_; +small-capitals have been transcribed as all capitals. [::] represents +the proportion symbol. + +More transcriber's notes and a list of corrections made may be found at +the end of this text. + + +[Illustration: FIG. 1] + + + + + A + PRACTICAL TREATISE + ON + GAS-LIGHT; + EXHIBITING + A SUMMARY DESCRIPTION + OF THE + APPARATUS AND MACHINERY + BEST CALCULATED FOR + ILLUMINATING + STREETS, HOUSES, AND MANUFACTORIES, + WITH + CARBURETTED HYDROGEN, OR COAL-GAS, + WITH REMARKS + ON THE + UTILITY, SAFETY, AND GENERAL NATURE OF THIS NEW BRANCH + OF CIVIL ECONOMY. + + BY FREDRICK ACCUM, + _OPERATIVE CHEMIST_, + LECTURER ON PRACTICAL CHEMISTRY, ON MINERALOGY, AND ON CHEMISTRY + APPLIED TO THE ARTS AND MANUFACTURES; MEMBER OF THE ROYAL + IRISH ACADEMY, FELLOW OF THE LINNÆN SOCIETY, MEMBER + OF THE ROYAL ACADEMY OF SCIENCES OF BERLIN, &c. &c. + + WITH SEVEN COLOURED PLATES. + + London: + PRINTED BY G. HAYDEN, BRYDGES-STREET, COVENT GARDEN; + FOR R. ACKERMANN, 101, STRAND; + _LONGMAN, HURST, REES, ORME, AND BROWN; AND SHERWOOD, NEELY, AND + JONES, PATERNOSTER ROW; AND J. HATCHARD, PICCADILLY_. + + _Price--Twelve Shillings in Boards._ + + 1815. + + + EX FUMO DARE LUCEM. + + HOR. + + + + +PREFACE. + + + _11, Compton Street Soho._ + +The following pages are intended to exhibit a summary view of the new +art of procuring light, by means of carburetted hydrogen gas obtained +from pit-coal, and which of late has been employed with unparalelled +success, as a substitute for candles and lamps, and is known by the name +of GAS-LIGHT. + +To accomplish this object, I have given, in the first part of this +Essay, a concise and popular view of the chemical theory and production +of artificial light--I have explained the action of candles and lamps--I +have shown the methods of measuring the comparative illuminating power +of artificial light of different kinds, so as to appreciate their +economical value--I have stated the proportions of combustible materials +requisite for producing a light of a certain strength; with such other +preliminary facts and observations as were deemed necessary to enable +the reader to understand fully the nature of the new art of +illumination, which it is the object of this Essay to describe. + +These positions are followed by a chemical view of the general nature +and composition of coal--the chemical changes which this substance +suffers, when employed in the production of gas-light--the different +products it furnishes--the modes of obtaining them--their properties and +applications in the various arts of life. + +I have given a description of the apparatus and machinery by means of +which the coal-gas is prepared, and the methods employed for +distributing and applying it as a substitute for candles and lamps to +illuminate houses, streets and manufactories;--I have furnished the data +for calculating the expense that must attend the application of this +species of light under different circumstances, so as to determine the +relative cost or value of gas-lights, when compared with the lights now +in use--together with such other practical directions and facts as will +enable the reader to form a proper estimate of the gas-light +illumination, and to put this art into practice. + +I have stated the leading objects of public and private utility to which +the new system of lighting may be successfully applied, candidly +pointing out those in which it cannot be made use of to advantage. + +I have detailed the most obvious effects which the discovery of lighting +with coal-gas must inevitably produce upon the arts and upon domestic +economy; its primary advantages--its views--its limits, and the +resources it presents to industry and public economy. I have endeavoured +to show how far its application is safe, and in what respect it is +entitled to public approbation and national encouragement. + +It may not be improper, before concluding, to inform the reader, that my +qualifications for the task I have undertaken are founded upon many +years experience, during which time, I possessed peculiar opportunities +to witness and verify the most extended series of operations that ever +have been made for the purpose of ascertaining the practicability, +safety, and general nature of the art of applying coal-gas as a +substitute for tallow and oil; and which have, as it were, fixed the +fate of this art. The numerous experiments I instituted, upon a large +scale, by desire of the Gas-Light Company, for the purpose of adducing +them in my evidence before the House of Commons, and House of Lords, on +a former occasion, have enabled me to collect such information as could +not have been obtained by other means. The substance of these results +(which are printed by order of Government,) are incorporated in this +Treatise, together with such other facts and observations as have +presented themselves in the routine of my profession elsewhere. + +To generalize the results of my observations, and to make them +practically useful to the public, is the aim of the present publication, +and I need scarcely add, that their suffrages to the zeal and industry, +at least, with which I have endeavoured to attain my object, will be a +source of infinite satisfaction. + + FREDRICK ACCUM + + + + +Contents. + + + INTRODUCTORY OBSERVATION. Page 1. + + Progress of the arts.--Influence of it upon the morals and condition + of man.--Beneficial tendency of chemical and mechanical improvements. + --State of pre-eminence of people with regard to civilization.--How to + be estimated.--Flourishing state of those nations which have shown the + greatest activity in cultivating the useful arts, and establishing + useful enterprises.--General observations on this subject.--Extra- + ordinary discoveries of modern times.--New art of procuring light.-- + Object of the treatise. + + + PART I. + + + PRODUCTION OF ARTIFICIAL LIGHT, &c. 8. + + Production of the flame generated during the combustion of certain + bodies.--Characters of flame when perfect.--Most luminous flame, how + produced with the least consumption of combustible matter.--Conditions + necessary for that purpose.--Importance of this subject, with regard + to the production and supply of artificial light.--The flame of bodies + may be tinged.--Blue flame, red flame, green flame, &c.--Opinion + concerning the origin of light emitted by bodies burning with flame.-- + Philosophy of the subject.--Theory of the action of the instruments of + illumination.--Rude method of procuring light employed in some + countries.--Chemical action of candles, and lamps.--Agency of the + tallow, oil, &c.--Office of the wick.--Reason why tallow candles + require snuffing, and wax candles snuff themselves--Further + observations on the subject. + + + METHOD OF ASCERTAINING THE ILLUMINATING POWER OF CANDLES, LAMPS, AND + OTHER LUMINOUS BODIES. 22. + + Optical principle assumed as law for determining the relative strength + of lights of different kinds.--Admeasurement of the intensities of + light.--Quantity of wax, tallow, oil, &c. requisite for producing a + light of a certain strength.--Method of increasing the light of tallow + candles, and to obviate the necessity of snuffing them.--A tallow + candle placed in an inclined position gives more light than when + placed perpendicularly and snuffed with an instrument.--Explanation of + the fact.--Further observations on this subject.--Comparative cost of + the light obtained by burning tallow candles of different sorts and + sizes. + + + PART II. + + + GAS-LIGHT. 47. + + Encouragement given by the legislature to the new system of procuring + light.--Gas-light company, incorporated by charter, to apply the new + art of illumination by way of experiment, on a large scale, to + illuminate the streets and houses of the metropolis.--Power and + authorities granted to this corporate body.--are very restricted, and + do not prevent other individuals from entering into competition with + them.--Boundaries of their experiments.--limit of capital employed by + them.--Power of His Majesty with regard to the gas-light charter. + + + THEORY OF THE COMBUSTION OF COAL IN ELUCIDATION OF THE NATURE OF GAS- + LIGHT. 49. + + Natural history of pit-coal.--Immediate constituent parts of coal.-- + Their relative quantities--are different in different kinds of coal.-- + Phenomena, which happen during the combustion of coal.--Analysis of + coal by distillation.--Great waste of matter capable of producing + light and heat, in the usual mode of burning coal.--Proofs of this + statement.--Theory of the production of gas-light, compared with the + production of light obtained by candles and lamps.--Place which the + discovery of lighting with gas occupies in the philosophical order of + knowledge. + + + HISTORICAL SKETCH OF THE RISE AND PROGRESS OF THE APPLICATION OF COAL- + GAS AS A SUBSTITUTE FOR PROCURING ARTIFICIAL LIGHT. 55. + + The discovery of the inflammable nature and application of coal-gas + for the production of artificial light, cannot be claimed by any body + now living.--Early notices of the inflammable property of the gas + obtained by distilling coal.--Attempts to substitute it for tallow and + oil.--Experiments made with coal-gas by Dr. CLAYTON, Dr. HALES, and + the Bishop of Llandaff.--First successful attempt of lighting manu- + factories with gas.--_Creditor_ and _debtor_ account concerning the + expence of this mode of illumination, when compared with the light + obtained by tallow candles.--Claims of Mr. MURDOCH with regard to the + economical application of coal-gas.--Claims of Mr. WINSOR.--Experi- + ments of Mr. NORTHERN, Mr. CLEGG, Mr. COOK, Mr. ACKERMANN.--Economical + statements of the gas-light illumination when compared with the cost + of the same quantity of light obtained by means of candles and lamps. + + + THEORY OF THE PRODUCTION OF GAS-LIGHT; AND DESCRIPTION OF A PORTABLE + APPARATUS FOR ILLUSTRATING, IN THE SMALL WAY, THE GENERAL NATURE OF + THE NEW SYSTEM OF PROCURING LIGHT. 77. + + Philosophy of the production of coal-gas.--Characters of the various + products which the gas-light process affords, their quantities, and + modes of obtaining them.--Quantity of gas obtainable from a given + weight of coal.--Illuminating power of a given bulk of coal-gas + compared with the illuminating power of a given weight of tallow + candles.--Practical directions with regard to the production of the + gas from coal.--Its chemical constitution and analysis.--Pit-coal is + not the only substance which affords carburetted hidrogen gas.--This + gas exists ready formed in nature.--Mode of collecting it when found + native.--Is given out by all kinds of vegetable matter, submitted to + distillation in close vessels.--Other sources of obtaining this + gazeous fluid.--Practical directions with regard to the method of + obtaining from coal, this gazeous substance, as best suited for + illumination.--Chemical constitution of coal-gas.--How ascertained. + + + UTILITY OF THE GAS-LIGHT ILLUMINATION WITH REGARD TO PUBLIC AND + PRIVATE ECONOMY. 99. + + Objects to which the new system of lighting with gas may be + beneficially applied.--Capital advantages of the gas-light illumina- + tion.--Places and public edifices lighted with coal-gas in this metro- + polis.--Situations best suited for the application of gas-lights.-- + places where it cannot be used to advantage.--Illumination of + barracks, arsenals, dock yards, &c. with coal-gas.--Further observa- + tions on this subject.--Great heat produced by gas-lights.--Reason why + the flame of coal-gas produces more heat than the flame of candles and + lamps.--Admeasurement of the comparative degrees of heat produced by + gas-lights, oil lamps, tallow and wax candles, &c.--Gas lamps and + burners, various kinds of.--Ornamental chandeliers and candelabras, + for applying coal-gas as a substitute for oil.--Other products obtain- + able from coal besides gas.--_Coke._--Its nature.--Combustion of it.-- + Produces a more strong and lasting heat than coal.--Explanation of + this fact.--Advantages resulting from the use of coke as fuel.--Disad- + vantages of its application in certain circumstances.--Relative effect + of heat produced by equal quantities of coke and charcoal.--Method of + measuring the comparative effect of different kinds of fuel in pro- + ducing heat.--Capital advantages resulting from the application of + coke, as fuel, in the art of burning lime.--Plaster of Paris, bricks, + &c.--Quantity of coke obtainable from a certain quantity of pit-coal. + --Kind of coke best suited for metallurgical operations.--Mode of + obtaining it in the gas-light process.--Sort of coke best adapted for + kitchen and parlour fires.--Manufacture of it.--_Coal tar._--How + obtained.--Its properties.--Earl of Dundonald's method of manufac- + turing tar from coal.--Quantity of coal-tar produced in the gas-light + process from a given quantity of coal.--Characters of coal tar + obtained from Newcastle coal, differ from that produced from canel + coal.--_Coal pitch._--Process for obtaining it.--Properties of coal- + pitch.--Use of it in the arts.--quantity of coal-pitch obtainable from + a given quantity of tar.--_Ammoniacal liquor_ produced during the + distillation of coal.--Its chemical constitution.--Quantity obtained + from a given quantity of coal.--General observation respecting the + scheme of applying coal-gas as a substitute for candles and lamps.-- + Effects which it must produce upon the arts and upon domestic economy. + --Its views.--Primary advantages.--Resources which it presents to + industry and public economy.--In what respect it is entitled to public + approbation and national encouragement.--Effects of prejudice against + the introduction of new and useful discoveries.--Have operated + strongly in retarding the gas-light illumination.--Remarkable slowness + with which improvements of extended utility make their way into common + use, contrasted with the rapid adoption of fashionable changes.--Other + causes unfavourable to the adoption of new and useful plans.--Further + observations on this subject.--The new system of lighting with coal- + gas can never supersede the use of candles and moveable lights.--Gas- + light illumination cannot prove injurious to the Greenland fishery-- + nor can it diminish the coal trade--must prove beneficial to it.--The + price of coal even when it is the highest cannot materially affect the + beneficial application of gas-lights.--Striking advantages to be + derived from the introduction of gas-lights into manufactories.-- + Principal expense which must always attend the gas-light illumination. + --Is the dead capital employed for erecting the machinery.--Floating + capital is small.--Advice to private individuals with regard to the + erection of a gas-light apparatus calculated for their own use.-- + Expence which must attend the application of the new system of + lighting under different circumstances.--Entire new scheme of + illuminating streets, or small towns, with gas-lights; which would + save all the main pipes for conveying the gas through the streets as + well as the branch pipes which conduct the gas to the lamps.--Manage- + ment of the gas-light machinery is extremely simple and easy.--The + apparatus not liable to be out of order.--Observations on the safety + of the gas-light illumination.--Misapprehension of the public con- + cerning it.--Causes that have alarmed the public concerning the + application of the new lights.--Gas-lights cannot give rise to those + accidents which have so often arisen from the careless snuffing of + candles, &c.--Produce no embers or sparks.--Cannot fall, or be dis- + turbed without becoming extinguished.--Are the safest of all lights.-- + Impossibility of streets or towns lighted with gas to be thrown + suddenly into darkness by the fracture of the gas-pipes conveying the + gas to the lamps--or by the destruction of one or more of the gas- + light machineries employed for preparing the gas.--Illustration + showing the absurdity of such mistaken notions.--Curious self-ex- + tinguishing lamp, invented by Mr. CLEGG.--His machine which measures + and registers in the absence of the observer, the quantity of gas + delivered by a pipe communicating with a gas-light _main_.--Leading + characters of the new lights.--Objects and views which this art + embraces.--It must lessen the consumption of oil.--Occasion a + defalcation in the revenue. + + + TABULAR VIEW, Exhibiting the quantity of GAS, COKE, TAR, PITCH, + ESSENTIAL OIL, and AMMONIACAL LIQUOR, obtainable from a given quantity + of COAL: together with an estimate of the quantity of Coal necessary + to produce a quantity of Gas, capable of yielding a Light equal in + duration of time and intensity to that produced by Tallow Candles of + different kinds. 164. + + + DESCRIPTION OF THE GAS-LIGHT APPARATUS. 166. + + METHOD of correcting the relative pressure of the Gasometer, so as to + cause the gas which it contains to be uniformly of an equal density. + 181. + + + DIRECTIONS TO WORKMEN ATTENDING THE GAS-LIGHT APPARATUS. 182. + + + ESTIMATE of the price of a Gas-Light Apparatus. 185. + + + LONDON Price List of the most essential articles employed in the + erection of a Gas-light Apparatus. 186. + + + + +ERRATA. + + + Page 24, line 11, _for_ too, _read_ two. + 48, 22, _for_ corporated, _read_ incorporated. + 53, 7, _for_ this combustion, _read_ the combustion. + 64, 24, _for_ CLEG, _read_ CLEGG. + _ibid_ 25, _for_ communicates, _read_ communicated. + 65, erase the * and put it after the word CLEGG, line + 24, p. 64. + _ibid_ 17, _for_ attemps, _read_ attempts. + 125, 23, _for_ degree, _read_ degrees. + 132, 25, _for_ coal, _read_ coal-tar. + + + + +DIRECTIONS TO THE BINDER: + + + Plate I. facing the title; plate II. facing page 79; plate III. facing + page 115; plate IV. facing page 119; plate V. facing page 120; and + plates VI. and VII. at the end of the book. + + + + + A + PRACTICAL TREATISE + ON + GAS-LIGHT. + + + + +INTRODUCTORY OBSERVATION. + + +INFLUENCE OF THE PROGRESS OF THE ARTS UPON THE MORALS AND CONDITION OF +MAN. + +It is an undoubted truth, that the successive improvements in the +condition of man, from a state of ignorance and barbarism, to that of +the highest cultivation and refinement, are usually effected by the aid +of machinery and expedients, calculated to procure the necessaries, the +comforts, and the elegancies of life; and that the pre-eminence of any +people in civilization is, and ought ever to be, estimated by the +proportional state of industry, and useful labour existing among them. + +In proof of this great and striking truth, no other argument requires to +be offered, than an immediate reference to the experience of all ages +and places: the various nations of the earth, the provinces of each +nation, the towns, and even the villages of the same province, differ +from each other in their accommodations; and are in every respect more +flourishing, the greater their activity in establishing new channels of +useful employ, calculated to procure the necessaries and comforts of +life. Hence the nations which have shewn the most ingenuity in this way, +are not only the richest, but also the most populous and the best +defended: the provinces of those nations, are seen to flourish likewise +in proportion to their respective degrees of activity in this respect, +And from these exertions it is, as SMITH[1] emphatically remarks, that +"the accommodation of an European prince does not always so much exceed +that of an industrious and frugal peasant, as the accommodation of the +latter exceeds that of many an African king, the absolute master of the +lives and liberties of ten thousand naked savages." + + [1] Wealth of Nations, chap. 1. + +It was a strange notion of Rousseau to maintain that mankind were +happier when they resembled wild beasts, than with all the expanded +knowledge of civilized life; and that the cultivation of their +understanding had tended to degenerate their virtues. There can be no +virtue but what is founded on a comprehensive estimate of the effects of +human actions, and an animal under the guidance of instinct can form no +such estimate. + +The variety of production, of wants, and fabrication of a civilized +society, has given rise to barter or exchange; mutual supply has +increased the sub-division of labour, and improved the means of +conveyance. Streams, roads, ships, and carriages have extended their +beneficial intercourse; confidence between man and man has advanced the +moral principles of society, and afforded a progression, of which the +past gradation may indeed be traced, but to the future part of which +the imagination can scarcely form a probable outline. And as the moral +and physical powers of man expand, new resources and new agencies are +made subservient to our commands, which, in an earlier state of society, +would have appeared altogether visionary. + +Who among the ancients would have listened to the extraordinary scheme +of writing books with such rapidity, that one man, by this new art, +should perform the work of twenty thousand amanuenses? What philosopher +would have given credit to the daring project of navigating the widest +ocean?--or imagined the astonishing effect of gun-powder--or the +extended application of the steam engine? What mortal would have dared +to dive to the bottom of the sea--or to soar aloft into the air--or bid +defiance to the thunder of the clouds? Discoveries which have changed, +as it were, the course of human affairs, and the effects of which have +already carried the intellectual operations of the human mind, to a +height they could by no other means have attained. The men of those +early ages, in the confidence of their own wisdom, might have derided +these discoveries as impossible, or rejected them as visionary; but to +those, who enjoy the full effects of such, and numerous other successful +inventions, it becomes a duty to reason upon different principles, and +to exert all means in their power to give effect to the progress of +useful knowledge. + +The artificial production and supply of light during the absence of the +sun, unquestionably holds a distinguished rank among the most important +arts of civilized life. + +If we could for a moment suppose the privation of artificial light, it +would follow as an immediate consequence that the greatest part of the +globe on which we dwell, would cease to be the habitation of man. +Whether he could ensnare or overtake those animals upon whose unprepared +remains he would then be compelled to feed--whether he might store the +fruits of the earth for his winter supply--what might be the physical +and moral consequences of a state of such desolation, may perhaps be +conjectured; but no estimate can show its dreadful magnitude. How much +do our comforts, and how greatly does the extent of our powers, in the +common affairs of life, depend upon the production and supply of +artificial light. The flame of a single candle animates a family, every +one follows his occupation, and no dread is felt of the darkness of +night. It might be a curious speculation to enquire how far, and in what +respects, the morals of men would become degraded by the want of this +contrivance. But it is sufficient on the present occasion, that, +previous to entering upon a dissertation respecting a new art of +illumination, a train of ideas has slightly been hinted at, which cannot +fail to show its magnitude and importance. The methods of procuring and +distributing light, during the absence of the sun, have not hitherto +attained the extent of their possible perfection: there is yet a wide +field for improvement in the construction of the instruments of +illumination, and the subject is highly deserving the attention of every +individual. + +The scheme of lighting houses, streets, and manufactories, by means of +the inflammable gas, obtainable by distillation from common pit-coal, +professes to increase the wealth of the nation, by adding to the number +of its internal resources, and on this ground it is entitled, at least, +to a candid examination. + +The apparent slight that has been thrown upon this new breach of civil +economy by some individuals, who appear to be incapable of judging of +its nature, has contributed to deter sensible and well disposed persons +from wishing it success. It is the more necessary to state this fact, +because, when a mistaken notion once becomes diffused, concerning the +nature of a new project, persons of the best intention are liable to +become affected with wrong impressions on their mind. I am neither a +share holder, nor a governor, nor am I directly or indirectly concerned +in any gas-light association. + +The object of the succeeding pages, simply is to rescue the art of +illumination with coal-gas from misconception and misrepresentation, and +by a fair, and not overcharged statement of its merits and its +disadvantages, to appeal from prejudice and ignorance, to the good sense +of the community. + + + + +PART I. + + +PRODUCTION OF ARTIFICIAL LIGHT; AND THEORY OF THE ACTION OF CANDLES AND +LAMPS. + +The flame of burning bodies consists of such inflammable matter in the +act of combustion as is capable of existing in a gazeous state. When all +circumstances are favorable to the complete combustion of the products, +the flame is perfect; if this is not the case, part of the combustible +body, capable of being converted into the gazeous state, passes through +the luminous flame unburnt, and exhibits the appearance of smoke. Soot +therefore always indicates an imperfect combustion. Hence flame is +produced from those inflammable substances only, which are either +totally volatile when heat is applied to them, so as not to alter their +chemical habitudes--or which contain a quantity of combustible matter +that is readily volatilized into vapour by heat, or the elements +necessary for producing such vapour or gazeous products, when the +chemical constitution of the body is altered by an increase of +temperature. And hence the flame of bodies is nothing else than the +inflammable product, either in a vaporous or in a permanently elastic +gazeous state. Thus originates the flame of wood and coal, when they are +burned in their crude state. They contain the elements of a quantity of +inflammable matter, which is capable of assuming the gazeous state by +the application of heat, and subsequent new chemical arrangements of +their constituent parts. + +As the artificial light of lamps and candles is afforded by the flame +they exhibit, it seems a matter of considerable importance to society, +to ascertain how the most luminous flame may be produced with the least +consumption of combustible matter. There does not appear to be any +danger of error in concluding, that the light emitted will be greatest +when the matter is completely consumed in the shortest time. It is +therefore necessary, that the stream of volatilized combustible gazeous +matter should pass into the atmosphere with a certain determinate +velocity. If the quantity of this stream should not be duly +proportioned; that is to say, if it be too large, its internal parts +will not be completely burned for want of contact with the air. If its +temperature be below that of ignition, it will not, in many cases, burn +when it comes into the open air. And there is a certain velocity at +which the quantity of atmospherical air which comes in contact with the +vapour will be neither too great nor too small; for too much air will +diminish the temperature of the stream of combustible matter so much as +very considerably to impede the desired effect, and too little will +render the combustion languid. + +We have an example of a flame too large in the mouths of the chimneys of +furnaces, where the luminous part is merely superficial, or of the +thickness of about an inch or two, according to circumstances, and the +internal part, though hot, will not set fire to paper passed into it +through an iron tube; the same defect of air preventing the combustion +of the paper, as prevented the interior fluid itself from burning. And +in the lamp of Argand we see the advantage of an internal current of +air, which renders the combustion perfect by the application of air on +both sides of a thin flame. So likewise a small flame is always whiter +and more luminous than a larger; and a short snuff of a candle giving +out less combustible matter in proportion to the circumambient air; the +quantity of light becomes increased to eight or ten times what a long +snuff would have afforded. + +The light of bodies burning with flame, exists previously either +combined with the combustible body, or with the substance which supports +the combustion. We know that light exists in some bodies as a +constituent part, since it is disengaged from them when they enter into +new combinations, but we are unable to obtain in a separate state the +basis with which it was combined. + +That in many cases the light evolved by artificial means is derived from +the combustible body, is obvious, if we recollect that the colour of +the light emitted during the process of combustion varies, and that this +variation usually depends not upon the medium which supports the process +of combustion, but upon the combustible body itself. Hence the colour of +the flame of certain combustibles, even of the purest kind may be tinged +by the admixture of various substances. + +The flame of a common candle is far from being of an uniform colour. The +lowest part is always blue; and when the flame is sufficiently +elongated, so as to be just ready to smoke, the tip is red or brown. + +As for the colours of flames that arise from coals, wood, and other +usual combustibles, their variety, which hardly amounts to a few shades +of red or purple, intermixed with the bright yellow light, seems +principally to arise from the greater or less admixture of aqueous +vapour, dense smoke, or, in short, of other incombustible products which +pass through the luminous flame unburnt. + +Spirit of wine burns with a blueish flame. The flame of sulphur has +nearly the same tinge. The flame of zinc is of a bright greenish white. +The flame of most of the preparations of copper, or of the substances +with which they are mixed, is vivid green. Spirit of wine, mixed with +common salt, when set on fire, burns with a very unpleasant effect, as +may be experienced by looking at the spectators who are illuminated by +such light. If a spoonful of spirit of wine and a little boracic acid, +or nitrate of copper be stirred together in a cup, and then be set on +fire, the flame will be beautifully green. If spirit of wine be mixed +with nitrate of strontia, it will, afterwards, on being inflamed, burn +with a carmine red colour. Muriate of lime tinges the flame of burning +spirit of wine of an orange colour.[2] + + [2] See Chemical Amusement, comprising minute instructions for + performing a series of striking and interesting chemical experiments, + p. 8, &c. + +Before we consider the general nature of Gas-Light, it will be necessary +to give a short sketch of the theory and action of the instruments of +illumination employed for supplying light, together with some other +facts connected with the artificial production and distribution of +light; such a proceeding will enable us to understand the general nature +of the new system of illumination which it is the object of this Essay +to explain. + +To procure light for the ordinary purposes of life, we are acquainted +with no other ready means than the process of combustion. + +The rude method of illumination consists, as is sufficiently known, in +successively burning certain masses of fuel in the solid state: common +fires answer this purpose in the apartments of houses, and in some +light-houses. Small fires of resinous wood, and the bituminous fossil, +called canel-coal, are in some countries applied to the same end, but +the most general and useful contrivance is that in which fat, or oil, of +an animal or vegetable kind is burned by means of a wick, and these +contrivances comprehend candles and lamps. + +In the lamp the combustible substance must be one of those which retain +their fluidity at the ordinary temperature of the atmosphere. The candle +is formed of a material which is not fusible but at a temperature +considerably elevated. + +All these substances must be rendered volatile before they can produce a +flame, but for this purpose it is sufficient to volatilize a small +quantity of any of them, successively; for this small quantity will +suffice to give a useful light, and hence we must admire the simple, yet +wonderful contrivance of a common candle or lamp. These bodies contain a +considerable quantity of the combustible substance, sufficient to last +several hours; they have likewise, in a particular place, a slender +piece of spongy vegetable substance, called the _wick_, which in fact is +the fire-place, or laboratory where the whole operation is conducted. + +There are three articles which demand our attention in the lamp--the +oil, the wick, and the supply of air. It is required that the oil should +be readily inflammable; the office of the wick appears to be chiefly, if +not solely, to convey the oil by capillary attraction to the place of +combustion; as the oil is decomposed into carburetted hydrogen gas and +other products, other oil succeeds, and in this way a continual current +and maintenance of flame is effected. + +When a candle is for the first time lighted, a degree of heat is given +to the wick, sufficient first to melt, and next to decompose the tallow +surrounding its lower surface; and just in this part the newly +generated gas and vapour is, by admixture with the air, converted into a +blue flame; which, almost instantaneously encompassing the whole body of +the vapour, communicates so much heat to it, as to make it emit a +yellowish white light. The tallow now liquefied, as fast as it boils +away at the top of the wick, is, by the capillary attraction of the same +wick, drawn up to supply the place of what is consumed by the cotton. +The congeries of capillary tubes, which form the wick, is black, because +it is converted into coal; a circumstance common to it with all other +vegetable and animal substances, when part of the carbon and hydrogen +which enter into their composition having been acted on by combustion, +the remainder and other fixed parts are by any means whatever covered +and defended from the action of the air. In this case, the burning +substance owes its protection to the surrounding flame. For when the +wick, by the continual wasting of the tallow, becomes too long to +support itself in a perpendicular situation, the top of it projects out +of the cone formed by the flame, and thus being exposed to the action of +the air, is ignited, loses its blackness, and is converted into ashes; +but that part of the combustible which is successively rendered volatile +by the heat of the flame is not all burnt, but part of it escapes in the +form of smoke through the middle of the flame, because that part cannot +come in contact with the oxygen of the surrounding atmosphere; hence it +follows, that with a large wick and a large flame, this waste of +combustible matter is proportionately much greater than with a small +wick and a small flame. In fact, when the wick is not greater than a +single thread of cotton, the flame, though very small, is, however, +peculiarly bright, and free from smoke; whereas in lamps, with very +large wicks, such as are often suspended before butchers' shops, or with +those of the lamp-lighters, the smoke is very offensive, and in great +measure eclipses the light of the flame. + +A candle differs from a lamp in one very essential circumstance; viz. +that the oil or tallow is liquefied, only as it comes into the vicinity +of the combustion; and this fluid is retained in the hollow of the part, +which is still concrete, and forms a kind of cup. The wick, therefore, +should not, on this account, be too thin, because if this were the case, +it would not carry off the material as fast as it becomes fused; and the +consequence would be, that it would gutter or run down the sides of the +candle: and as this inconvenience arises from the fusibility of the +tallow it is plain that a more fusible candle will require a larger +wick; or that the wick of a wax candle may be made thinner than that of +one of tallow. The flame of a tallow candle will of course be yellow, +smoky, and obscure, except for a short time after snuffing. When a +candle with a thick wick is first lighted, and the wick snuffed short, +the flame is perfect and luminous, unless its diameter be very great; in +which last case, there is an opake part in the middle, where the +combustion is impeded for want of air. As the wick becomes longer, the +interval between its upper extremity and the apex of the flame is +diminished; and consequently the tallow which issues from that +extremity, having a less space of ignition to pass through, is less +completely burned, and passes off partly in smoke. This evil increases, +until at length the upper extremity of the wick projects beyond the +flame and forms a support for an accumulation of soot which is afforded +by the imperfect combustion, and which retains its figure, until, by the +descent of the flame, the external air can have access to the upper +extremity; but in this case, the requisite combustion which might snuff +it, is not effected; for the portion of tallow emitted by the long wick +is not only too large to be perfectly burned, but also carries off much +of the heat of the flame, while it assumes the elastic state. By this +diminished combustion, and increased afflux of half decomposed oil, a +portion of coal or soot is deposited on the upper part of the wick, +which gradually accumulates, and at length assumes the appearance of a +fungus. The candle then does not give more than one-tenth of the light +which the due combustion of its materials would produce; and, on this +account, tallow candles require continual snuffing. But if we direct our +attention to a wax candle, we find that as its wick lengthens, the light +indeed becomes less. The wick, however, being thin and flexible, does +not long occupy its place in the centre of the flame; neither does it, +even in that situation, enlarge the diameter of the flame, so as to +prevent the access of air to its internal part. When its length is too +great for the vertical position, it bends on one side; and its +extremity, coming in contact with air, is burned to ashes; excepting +such a portion as is defended by the continual afflux of melted wax, +which is volatilized, and completely burned, by the surrounding flame. +Hence it appears, that the difficult fusibility of wax renders it +practicable to burn a large quantity of fluid by means of a small wick, +and that this small wick, by turning on one side in consequence of its +flexibility, performs the operation of snuffing itself, in a much more +accurate manner than can ever be performed mechanically. From the above +statement it appears, that the important object to society of rendering +tallow candles equal to those of wax, does not at all depend on the +combustibility of the respective materials, but upon a mechanical +advantage in the cup, which is afforded by the inferior degree of +fusibility in the wax: and that, in order to obtain this valuable +object, one of the following effects must be produced: either the tallow +must be burned in a lamp, to avoid the gradual progression of the flame +along the wick; or some means must be devised to enable the candle to +snuff itself, as the wax-candle does; or the tallow itself must be +rendered less fusible by some chemical process. The object is, in a +commercial point of view, entitled to assiduous and extensive +investigation. Chemists in general suppose the hardness or less +fusibility of wax to arise from oxygen. Mr. NICHOLSON[3] is led by +various considerations to imagine, that the spontaneous snuffing of +candles made of tallow or other fusible materials, will scarcely be +effected but by the discovery of some material for the wick, which shall +be voluminous enough to absorb the tallow, and at the same time +sufficiently flexible to bend on one side. + + [3] Philosophical Journal, 4to Series, Vol. I. p. 70. + + +METHOD OF ASCERTAINING THE ILLUMINATING POWER OF CANDLES, LAMPS, +GAS-LIGHTS, AND OTHER LUMINOUS BODIES. + +Though the eye is not fitted to judge of the proportional force of +different lights, it can distinguish, in many cases with great +precision, when two similar surfaces, presented together, are equally +illuminated. But as the lucid particles are darted in right lines, they +must spread uniformly, and hence their density will diminish in the +duplicate ratio of their distance. From the respective situations, +therefore, of the centres of divergency, when the contrasted surfaces +become equally bright, we may easily compute their relative degrees of +intensity. + +For this purpose it is assumed as a principle, that the same quantity of +light, diverging in all directions from a luminous body, remains +undiminished in all distances from the centre of divergency. Thus we +must suppose, that the quantity of light falling on every body, is the +same as would have fallen on the places occupied by the shadow; and if +there were any doubt of the truth of the supposition, it might be +confirmed by some simple experiment. Therefore, it follows, that, since +the shadow of a square inch of any surface occupies at twice the +distance of the surface from the luminous point the space of four square +inches, the intensity of the light diminishes as the square of the +distance increases. If, consequently, we remove two sources of light to +such distances from an object that they may illuminate it in equal +degrees, we may conclude that their original intensities are inversely +as the squares of the distances. + +Hence, if two lights of unequal illuminating powers shine upon the same +surface at equal obliquities, and an opake body be interposed between +them and the illuminated surface, the two shadows produced, must differ +in blackness or intensity in the same degree. For the shadow formed by +intercepting the greater light, will be illuminated by the smaller +light only, and reversely the other shadow will be illuminated by the +greater light: that is to say, the stronger light will be attended with +the deeper shadow. Now it is easy, by removing the stronger light to a +greater distance, to render the shadow which it produces at the common +surface equal to that afforded by the less. Experiments of this kind may +be conveniently made by fastening a sheet of white paper against the +wall of a room; the two lights, of whatever nature they are, intended to +be compared, must then be placed so that the ray of light from each +shall fall with nearly the same angle of incidence upon the middle of +the paper. In this situation, if a book or other object be held to +intercept part of the light which would have fallen on the paper, the +two shadows may be made to appear as in this figure; + +[Illustration] + +where A represents the surface illuminated by one of the lights only; B, +the surface illuminated by the other light; C, the perfect shadow from +which both lights are excluded. It will easily be understood that the +lights about D and E, near the angle F, will fall with equal incidences +when the double shadow is made to occupy the middle of the paper; and +consequently, if one or both of the lights be removed directly towards +or from the paper, as the appearances may require, until the two shadows +at E and D have the same intensity, the quantities of light emitted by +each will be as the squares of the distances from the paper. By some +experiments made in this way, the degree of illumination of different +lights may readily be ascertained to the tenth part of the whole. And, +by experiments of this kind, many useful particulars may be shewn. For, +since the cost and duration of candles, and the consumption of oil in +lamps, are easily ascertainable, it may be shewn whether more or less +light is obtained at the same expence during a given time, by burning a +number of small candles instead of one or more of greater thickness. It +will therefore be easy to compare the power of different kinds of lamps +or candles, or gas lights, so as to determine the relative cost of each +particular kind of the combustible substance employed for furnishing +light:--for example, if a candle and a gas-burner supplying coal-gas, +adjusted by a stop-cock, produce the same darkness of shadow, at the +same distance from the wall, the strength or intensity of light is the +same. An uniform degree of intensity of the gas-light may readily be +produced, by opening or shutting the stop-cock, if more or less be +required, and the candle is carefully snuffed to produce the most +regular and greatest quantity of light. The size of the flame in +experiments of this kind of course becomes unnecessary, and will vary +very much with the quality of the coal gas. The bulk of the gas +consumed, and the quantity of tallow used, by weighing the candle before +and after the experiment, furnish the data for ascertaining the relative +costs of tallow and gas-light, when compared with each other. + +From experiments made by Count RUMFORD, concerning the quantity of +materials requisite for producing a light of a certain intensity for a +given time: it was found that we must burn of wax 100, of tallow 101, of +oil, in an Argand's lamp, 129, of an ill-snuffed tallow candle 229 +parts, by weight. And with regard to the quantity of carburetted +hydrogen, or coal-gas, I have found that from 18 to 20 cubic feet +(according to the purity of the gas) are required to give a light equal +in duration and in illuminating powers to 1lb. of tallow candles, six to +the pound, provided they were set up and burnt out one after another.[4] + + [4] 112lbs. of Newcastle coal, called Tanfield Moor, produce, upon an + average, from 250 to 300 cubic feet of gas, fit for illumination. + + +FURTHER ILLUSTRATIONS OF THE MODE OF COMPUTING THE RELATIVE COST OR +VALUE OF LIGHT, EMITTED BY MEANS OF CANDLES, LAMPS, & OTHER BODIES. + +It is sufficiently known that the light of a candle, which is so +exceedingly brilliant when first snuffed, is very speedily diminished +to one-half and is usually not more than one-fifth or one-sixth before +the uneasiness of the eye induces us to snuff it.[5] Whence it follows, +that if candles could be made so as not to require snuffing, the average +quantity of light afforded by the same quantity of combustible matter +would be more than doubled. + + [5] Ezekiel Walker.--Nicholson's Journal, Vol. IV. 8vo. Series. + +When a lighted candle is so placed as neither to require snuffing or +produce smoke, it is reasonable to conclude that the whole of the +combustible matter which is consumed is converted to the purpose of +generating light; and that the intensities of light afforded in a given +time, by candles of different dimensions, are in proportion to the +quantity of matter consumed. That is to say; when candles are made of +the same materials, if one candle produce twice as much light as +another, the former will in the same time lose twice as much weight as +the latter. + +To prove the truth of this position, Mr. Walker made the experiments +contained in the following + +TABLE. + + +-----------+--------+--------+-----------+--------+---------+ + | | | | Weight | | | + | | | | of the | |Distance | + | No. of | No. of |Time of | Candles |Strength| of the | + | the | the |burning.| consumed | of | Candles | + |Experiment.|Candles.| | in a | Light. |from the | + | | | | given | | Wall. | + | | | | time. | | | + +-----------+--------+--------+-----------+--------+---------+ + | | | h. | oz. dr. | | Feet. | + | {| 1 | 3 0 | 0 15 | 1 | 7 | + | 1 {| 3 | 3 0 | 1 1-1/2| 1 + | 7 | + | {| Mould | 3 0 | 0 15 | 1 | 7 | + +-----------+--------+--------+-----------+--------+---------+ + | {| 1 | 2 55 | 0 15 | 1 | 8 | + | 2 {| 3 | 2 55 | 1 0 | 1 + | 8 | + | {| Mould | 2 55 | 0 15 | 1 | 8 | + +-----------+--------+--------+-----------+--------+---------+ + | {| 1 | 3 0 | 0 15-3/4| 1 | 8 | + | 3 {| 3 | 3 0 | 1 2 | 1-1/8 | 8-3/4| + | {| Mould | 3 0 | 0 0 | 1 | 9 | + +-----------+--------+--------+-----------+--------+---------+ + | 4 {| 5 | 3 0 | 1 5 | 1.18 | 8-3/4| + | {| Mould | 3 0 | 1 1-1/8| 1. | 8 | + +-----------+--------+--------+-----------+--------+---------+ + +These experiments, Mr. Walker informs us, were made in the following +manner:-- + +Three candles, the dimensions of which are given in the table, against +1, 3, and mould. These were first weighed, and then lighted at the same +instant. At the end of the time inserted in the third column of the +above table, they were extinguished and weighed again, and the loss of +weight of each candle is contained in the fourth column. + +The three first experiments were made under such favourable +circumstance, that there was little doubt of their results being more +accurate than what practical utility requires, but the fourth experiment +cannot be depended on so much, in consequence of the variable light of +No. 5. This candle was moved so often to keep the two shadows equal, +that it was found necessary to set down its mean distance from the wall +by estimation; but as this was done before the candles were weighed, the +experimenter's mind could not be under the influence of partiality for a +system. + +The method which Mr. Walker employed in comparing one light with another +in each experiment, was that which has been described page 24. + +1. The experiments were made at different times, and the light of the +mould candle was made the standard, with which the lights of the others +were compared; but it must not be understood, that this candle gave the +same strength of light in every experiment. + +2. The sign + in the 5th column, signifies that the candle against +which it is placed, gave a stronger light than the others. + +From the experiments contained in the table, it appears to be an +established law, where combustion is complete, that the quantities of +light produced by tallow candles, are in the complicate ratio of their +times of burning and weights of matter consumed. + +For if their quantities of matter be equal, and times of burning the +same, they will give equal quantities of light, _by the experiments_. + +And if the times of burning be equal, the quantities of light will be +directly as their weights of matter expended. + +Therefore the light is universally in the compound ratio of the time of +burning and weight of matter consumed. + +If the law which Mr. Walker has endeavoured to prove, both by reason and +experiment, be admitted, we have a standard with which we may compare +the strength of any other light. + +Let a small mould candle, when lighted, be so placed as neither to +produce smoke nor require snuffing, and it will lose an ounce of its +weight in three hours. Let this quantity of light produced under these +circumstances, be represented by 1.00. + +Then should this candle at any other time, lose more or less of its +weight in three hours than an ounce, the quantity of light will be still +known, because the quantity of light in a given time is directly as the +weight of the candle consumed.[6] + + [6] To investigate rules for this purpose, 1. Let M represent the + mould candle, _a_ its distance from the wall, on which the shadows + were compared, _x_ its quantity of matter consumed in a given time, + (_t_) and Q the quantity of light emitted by M in the same time: 2. + Let _m_ represent any other candle, _b_ its distance from the same + wall, and _y_ its quantity of matter consumed, in the time _t_. + + Then as the intensities of light are directly as the squares of the + distances of the two candles from the wall, we have as _a_² : Q [::] + _b_² : (_b_² + Q)/_a_² = the quantity of light, emitted by _m_ in the + time. + + Then let us suppose that the quantities of light are directly as the + quantities of matter consumed in the time _t_, and we have, As _x_ : Q + [::] _y_ : (_y_ + Q)/_x_ = the quantity of light emitted by _m_ in + that time, by hypothesis. + + Now, when (_b_² + Q)/_a_² (Theo. 1.) is = (Y + Q)/X (Theo. 2.) the + quantities of light of M and _m_ are directly as their quantities of + matter consumed in any given time. + + +METHOD OF INCREASING THE LIGHT OF TALLOW CANDLES, AND TO OBVIATE THE +NECESSITY OF SNUFFING THEM. + +Mr. EZEKIEL WALKER has shewn that, if a trifling alteration be made in +the method of using common tallow candles, they will become excellent +substitutes for those of wax. + +A common candle, weighing one-tenth of a pound, containing fourteen +single threads of fine cotton, placed so as to form an angle of 30 +degrees[7] with the perpendicular, and lighted, requires no snuffing; +and what is much more valuable for some purposes, it gives a light that +is nearly uniform in strength without the least smoke. These effects are +thus produced: + + [7] Candlesticks may be made to hold the candle at this angle, or they + may be so contrived as to hold the candle at any angle at pleasure. + +When a candle burns in an inclined position, most part of the flame +rises perpendicularly from the upper side of the wick, and when viewed +in a certain direction, it appears in the form of an obtuse angled +triangle. And as the end of the wick projects beyond the flame at the +obtuse angle, it meets with the air, and is completely burnt to ashes: +hence it is rendered incapable of acting as a conductor to carry off +part of the combustible matter in the form of smoke. By this spontaneous +mode of snuffing, that part of the wick which is acted upon by the flame +continues of the same length, and the flame itself very nearly of the +same strength and magnitude[8]. + + [8] The wick's not being uniformly twisted throughout, may occasion a + little variation in the dimensions of the flame. + +The advantages which may be derived from candles that require no +snuffing and afford no smoke, may be readily understood; but these +candles have another property which ought not to be passed over in +silence. A candle snuffed by an instrument gives a very fluctuating +light, which, in viewing near objects is highly injurious to the eye; +and this is an inconvenience which no shade can remove. But when a +candle is snuffed spontaneously, it gives a light so perfectly steady +and so uniformly bright, that the adjustments of the eye remain at rest, +and distinct vision is performed without pain, and without uneasiness. + +Candles, on which Mr. WALKER has made experiments, are described in the +following + +TABLE. + + +-----+--------------+---------+---------------+ + | |No. of candles| | No. of single | + | No. | to the pound |Length in|threads of fine| + | | avoirdupoise | inches. | cotton in the | + | | weight. | | wick. | + +-----+--------------+---------+---------------+ + | 1 | 14 | 8.5 | 10 | + | 2 | 13 | 9. | 12 | + | 3 | 10 | 9.74 | 14 | + | 4 | 8 | 10. | 20 | + | 5 | 6 | 10.25 | 24 | + |Mould| 6 | 13. | | + +-----+--------------+---------+---------------+ + +Number 1, 2, and 3. These candles, when lighted and placed to form an +angle of 30° with the perpendicular, require no snuffing: they give +lights which are nearly equal, and combustion proceeds so regularly, +that no part of the melted tallow escapes unconsumed, except from +accidental causes. + +No. 4, placed at the angle mentioned above, and lighted, requires no +snuffing: it gives a light very little stronger than No. 1, but its +colour is not quite so white, nor its flame so steady. + +No. 5. This candle, placed at an angle of 30°, and lighted, requires no +snuffing; its flame is rather fluctuating, and not so white as No. 4, +nor is its strength of light much greater than No. 1. The melted tallow +sometimes overflows when the air in the room is put in motion; yet the +light of this candle is much improved by being placed in an inclined +position. + +The mould candle, treated in the same manner, affords a very pure steady +flame, without smoke and without snuffing, and its strength of light is +about equal to that of No. 1. + +The experiments have not been sufficiently numerous to determine with +precision which of these candles affords the most light at a given +expence, but the few experiments which have been made seem to indicate, +that the quantity of light is nearly as the quantity of combustible +matter consumed, and thus a candle which is used in the manner pointed +out gives more light than a candle of the same dimension set +perpendicularly and snuffed, because one part of a candle that is +snuffed, is thrown away, and another part flies off in the form of +smoke. And this is not the only inconvenience that attends the using +candles in this manner, and which the other method is free from, for the +light which it gives is of a bad quality, on account of its being +variable and undulating. + +From the time that a candle is snuffed till it wants snuffing again, its +strength of light scarcely continues the same for a single minute. And +that variation which frequently takes place in the height of the flame, +is a matter of still more serious consequence. + +The flame of a long candle placed vertically when it is snuffed burns +steadily, is about two inches high, but it very frequently rises to the +height of four inches or upwards; drops down again in a moment, till it +is less than three inches, and then rises again. In this manner the +flame continues in motion for some time before it returns to its +original dimensions. But it does not continue long in a quiescent state +before it begins a new series of undulations. In this manner the candle +burns till the top of the wick is seen near the apex of the flame, +carrying off clouds of smoke. In this state of things the eye becomes +uneasy for want of light, and the snuffers are applied to remove the +inconvenience. + +Mr. WALKER further observes, that it is these sudden changes, and not +the nature of candle-light itself, that do so much injury to the eye of +the student and artist; and that that injury may be easily prevented, by +laying aside the snuffers, and in the place of one large candle, let two +small ones be used in the manner stated. + +The following observations on this subject are copied from the Monthly +Magazine, 1805, p. 206. + +"It is scarcely necessary to observe, that the combustion of candles +proceeds the quicker in proportion as the inclination is greater. From +the experiments which I have made, I should consider an angle of forty +degrees with the perpendicular as the maximum of inclination, beyond +which several considerable inconveniencies would occur; and I should +take 25 degrees as the minimum of inclination, less than which does not +sufficiently expose the point of the wick to the action of the air. + +"By those who are much in the habit of reading or writing by +candle-light, it will also be esteemed no inconsiderable addition to the +advantages already mentioned, that the trouble of seeking and applying +the snuffers is superseded. A candle of common size in a vertical +position, requires the application of the snuffers forty-five times +during its complete consumption. + +"But I found an obstacle to the adoption of Mr. WALKER's plan, which, +from the inclined position of the candle, it did not immediately occur +to me by what means to counteract. Any agitation of the air of the room, +occasioned either by the opening or shutting of a door, or by the quick +passage of a person near the candle, caused the melted tallow to run +over, or, in more familiar language, caused the candle to gutter; which, +with the candle in this position, became an insuperable bar to the use +of it. + +"For the prevention of this inconvenience, I have had a wire +skeleton-shade adapted to a rod bearing the same inclination as the +candle, and which at bottom joins the candlestick in an horizontal line +of about two inches, terminating in a nozzle fitting that of the +candlestick.--The distance of this rod from the candlestick, or, which +is the same thing, the length of the foot or horizontal line, is of +course to be determined by the distance between the two circles which +form the upper and lower apertures of the shade.--It may serve, perhaps, +more familiarly to describe this part of the apparatus, to state, that +it bears a perfect resemblance to the two first strokes of the written +figure 4; and the third stroke, if carried up as high as the first, and +made sloping instead of upright, will very well represent the situation +of the candle. + +"When a strong light, for the purposes of reading or writing, be +required, a white silk or paper may be used, as is common, over the +skeleton; but when it be required that the light should be dispersed +over the room, a glass of a similar shape may be adopted, for the +purpose of preventing the flame from being influenced by any agitation +of the air of the room. If the upper circle of the shade be four inches +in diameter, the apex of the flame will be within it during more than +half the time of the complete consumption of the candle; the shade will +not, therefore, require adjusting for the purpose of preventing injury +to the silk, or whatever else may be used over the skeleton, more than +once during that time. + +"Being myself much averse to the interruptions which a candle used in a +vertical position occasions, and which, though short, may, under some +circumstances, be highly vexatious, I wish to extend to others a benefit +which I prize rather highly." + +Lord STANHOPE[9] has published a simple method of manufacturing candles, +which, according to his Lordship's statement, is superior to the method +usually employed. The principles upon which the process depends are the +following:--First, the wick of the candle is to have only three-fourths +of the usual number of cotton threads, if the candle be of wax or +spermaceti; and only two-thirds of the usual number, if the candle be of +tallow. Secondly, it is required that the wick in all cases be perfectly +free from moisture, a circumstance seldom attended to in the +manufacturing of candles; and thirdly, to deprive the wick of wax +candles, of all the air which is entangled in its fibres, and this may +conveniently be done, by boiling it in melted wax, till no more air +bubbles, or froth appear on the surface of the fluid. + + [9] Repository of Arts, Vol. I, p. 86. + +If these circumstances be attended to, three candles of any size thus +prepared, last as long as four of the same size manufactured in the +common way. The light which they afford is superior and more steady than +the light of common candles; and lastly, candles made in this manner, +whether of wax, spermaceti, or tallow, do not require to be snuffed as +often. Besides all this, they flame much less, and are consequently +better for writing, reading, working and drawing, than candles made by +the common method. + +The following observations will enable any person who is willing to try +the candles manufactured according to Lord Stanhope's plan, to ascertain +the real value of the improvements suggested by his Lordship. It shews +also the result of some experiments, made to ascertain the expence of +burning oil in lamps with wicks of various sizes. + +A taper lamp, with eight threads of cotton, will consume in one hour +225/1000 oz. of spermaceti oil: at six shillings per gallon, the expence +of burning twelve hours is 13.71 farthings. + +At seven shillings, it is 15.995 farthings. + +At eight shillings, it is 18.280 farthings. + +N. B. This gives as good a light as tallow candles of eight and ten in +the pound. This lamp seldom wants snuffing, and casts a steady and +strong light. + +A taper, chamber, or watch lamp, with four ordinary threads of cotton in +the wick, consumes 1.664 oz. of spermaceti oil in one hour: the oil at +seven shillings per gallon, the expence of burning twelve hours, 7.02 +farthings. + +At eight shillings, it is 8.022 farthings. + +At nine shillings, it is 9.024 farthings. + +TABLE, + + Exhibiting a series of experiments, made with a view to determine the + real and comparative expence of burning candles of different sorts and + sizes. + + +-------+---------+-----------+--------+----------+-----------------+ + | |Number of| Weight of |Time one|The time |The expence in | + | | candles |one candle.| candle |that one |twelve hours when| + | | in one | | lasted.|pound will|candles are at | + | | pound. | | |last. |12s. per dozen, | + | | | | | |which also shews | + | | | | | |the proportion of| + | | | | | |expence at any | + | | | | | |price, per dozen.| + | +---------+-----------+--------+----------+-----------------+ + | | | | | |Farthings and | + | | | Oz. Dr. |Hr. Min.| Hr. Min. |hundredth parts. | + |A small| 18-3/4 | 0 14 | 3 15 | 59 26 | 9.70 | + |wick. | 19 | 0 13-1/2| 2 40 | 50 34 | 11.40 | + |A large| 16-1/2 | 0 15-1/2| 2 40 | 44 2 | 13.08 | + |wick. | 12 | 1 5-1/4| 3 27 | 41 24 | 13.92 | + | | 10-3/4 | 1 8 | 3 36 | 38 24 | 15.00 | + | | 7-3/4 | 2 1 | 4 9 | 32 12 | 17.88 | + | | 8 | 2 0 | 4 15 | 34 0 | 16.94 | + | | 5-3/4 | 2 13 | 5 19 | 30 15 | 19.06 | + | |Mould | | | |Moulds at 14d. | + | |candles. | Each. | | | per dozen. | + |With | 3-7/8 | 2 12 | 7 20 | 42 39 | 15.74 | + |wax'd | 4 | 4 0 | 9 3 | 36 20 | 18.56 | + |wick. | 3 | 5 2-3/4|17 30 | 52 30 | 16.825 | + +-------+---------+-----------+--------+----------+-----------------+ + +The time each candle lasted, was taken from an average of several trials +on each size. + +It has been suggested by Dr. FRANKLIN, that the flame of two candles +joined, gives a much stronger light than both of them separately. The +same, has been observed by Mr. WARREN, to be the case with flames of +gas-lights, which, when combined, give a much stronger light than they +would afford, when in a separate state. + +Indeed, in all cases, where flames for producing light are placed near +to each other, it is always beneficial to preserve the heat of the flame +as much as possible. One of the most simple methods of doing this, is no +doubt, the placing of the several flames together, and as near as +possible to each other without touching, in order that they may mutually +cover and defend each other against the powerful cooling influence of +the surrounding cold bodies. This principle is now employed in the +Liverpool lamp, which acts by several flat or ribband wicks placed in +the form of a cylinder. The power of illumination of this lamp is +superior in effect and more economical than any other lamp in use--and +as flame is perfectly transparent to the light of another flame which +passes through it, there is no danger of loss of light on account of the +flames covering each other. + + + + +PART II. + + +GAS-LIGHT. + + +PRELIMINARY OBSERVATION. + +A new art of procuring artificial light, which consists in burning the +gazeous fluid obtained by distillation from common pit-coal, has of late +engaged the attention of the public, under the name of _gas-light_. + +The encouragement that has been given for some years past by the +legislature to this system of lighting, has induced certain individuals +to apply the coal-gas light for the illumination of streets, houses, +roads, and public edifices. And it is sufficiently known that a company +has been incorporated by charter under the name of the "_Gas Light and +Coke Company_," to apply this new art of procuring light, by way of +experiment, on a large scale, in lighting the streets of the +metropolis.[10] + + [10] An Act for granting certain powers and authorities to a company + to be incorporated by charter, called the "Gas Light and Coke + Company," for making inflammable air for the lighting of the streets + of the metropolis, &c.--Session 1810, 50th Geo. III. + +The power and authorities granted to this corporate body are very +restricted and moderate. The individuals composing it have no exclusive +privilege; their charter does not prevent other persons from entering +into competition with them. Their operations are confined to the +metropolis where they are bound to furnish not only a stronger and +better light to such streets and parishes as chuse to be lighted with +gas, but also at a cheaper price than shall be paid for lighting the +said streets with oil in the usual manner. The corporation is not +permitted to traffic in machinery for manufacturing or conveying the gas +into private houses, their capital or joint stock is limited to +200,000_l._ and His Majesty has the power of declaring the gas-light +charter void, if the company fail to fulfil the terms of it. + + +THEORY OF THE COMBUSTION OF COAL IN ELUCIDATION OF THE NATURE AND +PRODUCTION OF GAS LIGHT. + +Pit-coal exists in this island in strata, which, as far as concerns many +hundred generations after us, may be pronounced inexhaustible; and is so +admirably adapted, both for domestic purposes and the uses of the arts, +that it is justly regarded as a most essential constituent of our +national wealth. Like all other bituminous substances, it is composed of +a fixed carbonaceous base or bitumen, united to more or less earthy and +saline matter constituting the ashes left behind when this substance is +burnt. The proportions of these parts differ considerably, in different +kinds of coal; and according to the prevalency of one or other of them, +so the coal is more or less combustible, and possesses the characters +of perfect pit-coal; and by various shades, passes from the most +inflammable canel-coal, into blind, Kilkenny, or stone-coal; and, +lastly, into a variety of earthy or stony substances; which, although +they are inflammable, do not merit the appellation of coal. + +Every body knows that when pit-coals are burning in our grates, a flame +more or less luminous issues from them, and that they frequently emit +beautiful streams of flame remarkably bright. But besides the flame, +which is a peculiar gas in the state of combustion, heat expels from +coal an aqueous vapour, loaded with several kinds of ammoniacal salts, a +thick viscid fluid resembling tar, and some gases that are not of a +combustible nature. The consequence of which is, that the flame of a +coal-fire is continually wavering and changing, both in shape, as well +as brilliance and in colour, so that what one moment gave a beautiful +bright light, in the next, perhaps, is obscured by a stream of thick +smoke. + +But if coals, instead of being suffered to burn in this way, are +submitted to distillation in close vessels, all its immediate +constituent parts may be collected. The bituminous part is melted out +in the form of tar. There is disengaged at the same time, a large +quantity of an aqueous fluid, contaminated with a portion of oil, and +various ammoniacal salts. A large quantity of carburetted hidrogen, and +other uninflammable gases, make their appearance, and the fixed base of +the coal remains behind in the distillatory apparatus in the form of a +carbonaceous substance, called coke. + +All these products may be separately collected in different vessels. The +carburetted hidrogen, or coal-gas, may be freed from the non-inflammable +gases, and afterwards forced in streams out of small appertures, which, +when lighted, may serve as the flame of a candle to illuminate a room or +any other place. It is thus, that from pit-coal a native production of +this country, we may procure a pure, lasting, and copious light; which, +in other cases, must be derived from expensive materials, in part +imported from abroad. + +It is chiefly upon the power of collecting the products afforded by +coal, with convenience and cheapness, that the promoters of the +gas-light illumination found their claims to public encouragement. They +conceive that the flame which pit-coal yields, as it is now consumed, +is turned to very little advantage: it is not only confined to one +place, where a red heat is more wanted than a brilliant flame, but it is +obscured, and sometimes entirely smothered, by the quantity of +incombustible materials that ascend along with it and pollute the +atmosphere. + +That much inflammable matter is thus lost, is evident from facts that +come under our daily observation. We often see a flame suddenly burst +from the densest smoke, and as suddenly disappear; and if a light be +applied to the little jets that issue from the bituminous parts of the +coal, they will catch fire, and burn with a bright flame. A considerable +quantity of a gazeous fluid, capable of affording light and heat +continually escapes up the chimney, whilst another part is occasionally +ignited, and exhibits the phenomena of the flame and light of the fire. + +The theory of the production of gas-light is therefore analogous to the +action of a lamp or candle. The wick of a candle being surrounded by the +flame, is in the same situation of the pit-coal exposed to distillation. +The office of the wick is chiefly to convey tallow, by capillary +attraction, to the place of combustion. As it is decomposed into +carburetted hidrogen gas it is consumed and flies off, another portion +succeeds; and in this way a continued current of tallow and maintenance +of flame are effected. See page 15. + +The combustion of oil by means of a lamp depends on similar +circumstances. The tubes formed by the wick serve the same office as a +retort placed in a heated furnace through which the inflammable liquid +is transmitted. The oil is drawn up into these ignited tubes, and is +decomposed into carburetted hidrogen gas, and from the combustion of +this gas the illumination proceeds. See p. 15. What then does the +gas-light system attempt? Nothing more than to generate, by means of +sufficient furnaces and a reservoir of sufficient capacity, desired +quantities of the gas, which is the same material of the flame of +candles or lamps; and then by passing it through pipes to any desired +distance, to exhibit it there at the mouths of the conducting tubes, so +that it may be ignited for any desired purpose. The only difference +between this process and that of an ordinary candle or lamp, consists in +having the furnace at the manufactory, instead of its being in the wick +of the candle or lamp--in having the inflammable material distilled at +the station, instead of its present exhibitions in oil, wax, or tallow, +and then in transmitting the gas to any required distance, and igniting +it at the orifice of the conducting pipe instead of igniting it at the +apex of the wick. The principle is rational, and justified by the +universal mode in which all light is produced. Indeed, this discovery +ranks among the numerous recent applications of chemical science to the +purposes of life, which promise to be of the most general utility. + +It is evident from the outline here given of the production and +application of coal-gas, that all the uses of pit-coal are not +exhausted; it will be sufficient to observe, that the complete analysis +of coal, which has been hitherto confined to the laboratory of the +chemist, requiring skill and nicety in the operator, and attended with +great trouble and expence, is now so far simplified, that many chaldrons +of coals may be decomposed by one gas-light apparatus in the space of +six hours, and all the component parts produced in their most useful +shape, at an expence out of all proportion below the value of the +products. + + +SKETCH OF THE RISE AND PROGRESS OF THE DISCOVERY AND APPLICATION OF +COAL-GAS, AS A SUBSTITUTE FOR PROCURING ARTIFICIAL LIGHT. + +To assist the reader in comprehending the nature and object of +substituting coal-gas for tallow or oil, for the purpose of obtaining +light, it may be proper to touch slightly upon the successive +discoveries that have been made as to the decomposition of coal, and the +application of its different ingredients. Such a sketch will add to the +many examples that occur in the history of science and art, showing the +slow progress of mankind in following up known principles, or extracting +from acknowledged facts every possible advantage. + +In the Philosophical Transactions of the Royal Society, V. XLI. so long +ago as the year 1739, is recorded a paper, exhibiting an account of some +experiments made by Dr. James Clayton, from which it appears that the +inflammable nature of coal-gas was then already known. Dr. Clayton +having distilled Newcastle coal, obtained, as products of the process, +an aqueous fluid, a black oil, and an inflammable gas, which he caught +in bladders, and by pricking these he was enabled to inflame the gas at +pleasure. + +It is further known, that in the beginning of the last century, Dr. +Hales[11] on submitting pit-coal to a chemical examination, found, that +during the ignition of this fossil in close vessels, nearly one-third of +the coal became volatilized in the form of an inflammable vapour. Hence +the discovery of the inflammable nature of coal-gas can no longer be +claimed by any person now living. + + [11] Vegetab. Statics, vol. I. + +In the year 1767, the Bishop of Llandaff[12] examined the nature of the +vapour and gazeous products evolved during the distillation of pit-coal. +This learned philosopher noticed, that the volatile product is not only +inflammable as it issues from the distillatory vessel, but that it also +retained its inflammability after having been made to pass through +water, and suffered to ascend through two high curved tubes. The solid +matters obtained by this venerable prelate, were, an aqueous ammoniacal +fluid, a tenaceous oil, resembling tar, an ammoniacal liquor, and a +spongy coal, or coke. + + [12] Watson's Chemical Essays, vol. II. + +The first discovery and application of the use of coal-gas for the +purpose of illumination is claimed by Mr. Murdoch. + +Dr. W. Henry of Manchester, has published the following account[13] of +this discovery. + + [13] Thompson's System of Chemistry, vol. I. p. 52. + +"In the year 1792, at which time Mr. Murdoch resided at Redruth, in +Cornwall, he commenced a series of experiments upon the quantity and +quality of the gases contained in different substances. In the course of +these he remarked, that the gas obtained by distillation from coal, +peat, wood, and other inflammable substances, burnt with great +brilliancy upon being set fire to; and it occurred to him, that by +confining and conducting it through tubes, it might be employed as an +economical substitute for lamps and candles. The distillation was +performed in iron retorts, and the gas conducted through tinned iron and +copper tubes to the distance of 70 feet. At this termination, as well as +at intermediate points, the gas was set fire to, as it passed through +apertures of different diameters and forms, purposely varied with a view +of ascertaining which would answer best. In some the gas issued through +a number of small holes like the head of a watering pan; in others it +was thrown out in thin long sheets; and again in others in circular +ones, upon the principle of Argand's lamp. Bags of leather and of +varnished silk, bladders, and vessels of tinned iron, were filled with +the gas, which was set fire to, and carried about from room to room, +with a view of ascertaining how far it could be made to answer the +purpose of a moveable or transferable light. Trials were likewise made +of the different quantities and qualities of gas produced by coals of +various descriptions, such as the Swansea, Haverfordwest, Newcastle, +Shropshire, Staffordshire, and some kinds of Scotch coals. + +"Mr. Murdoch's constant occupations prevented his giving farther +attention to the subject at that time; but he again availed himself of a +moment of leisure to repeat his experiments upon coal and peat at Old +Cumnock, in Ayrshire, in 1797; and it may be proper to notice that both +these, and the former ones, were exhibited to numerous spectators, who, +if necessary, can attest them. In 1798, he constructed an apparatus at +Soho Foundry, which was applied during many successive nights to the +lighting of the building; when the experiments upon different apertures +were repeated and extended upon a large scale. Various methods were also +practised of washing and purifying the air, to get rid of the smoke and +smell. These experiments were continued, with occasional interruptions, +until the epoch of the peace in the spring of 1802, when the +illumination of the Soho manufactory afforded an opportunity of making a +public display of the new lights; and they were made to constitute a +principal feature in that exhibition." + +In the year 1803 and 1804, Mr. Winsor exhibited at the Lyceum in London +the general nature of this new mode of illumination though the +machinery for procuring, and the manner of purifying the gas, he kept a +secret. He exhibited the mode of conducting the gas through the house, +and a number of devices for chandeliers, lamps, and burners, by which it +might be applied. Among these he proposed long flexible tubes suspended +from the ceiling, or wall of the room, and at the end communicating with +burners or lamps of different kinds. This gentleman showed also by +experiment, that the flame of the gas-light, produced no smoke; that it +was not so dangerous as the flame of candles or lamps; that it could not +produce sparks; and that it was not so readily extinguished by gusts of +wind or torrents of rain. + +Mr. WINSOR's display of gas-lights took place more than two years before +Mr. MURDOCH's priority of right was heard of. + +In stating these facts I do not mean to say that Mr. MURDOCH derived the +hint of applying the coal-gas from the previous exhibition of Mr. +WINSOR, because it is quite within the bounds of probability that the +ideas of Mr. MURDOCH may have arisen totally independent of all +acquaintance with Mr. WINSOR's. + +The claims of invention, or the determination of the right of priority, +concerns the public only so far as the honour and estimation of any +useful discovery conferred on the inventor may induce other individuals +to devote their talents to similar pursuits; by means of which, more +discoveries may be made, and the subject of human invention become +extended, or rendered more useful. For as the mere benefits which +mankind may derive from any particular discovery, they are certainly +more indebted to the person who first applied the discovery to actual +practice, than to him who first made it, and merely illustrated it by +barren experiments. Mr. WINSOR certainly pressed on the mind of the +public with unremitted perseverance and diligence the extensive +application of gas-light in the year 1802, but he made no new discovery +with regard to the composition of coal; he did not even invent the mode +of conducting the gas through tubes; and if he has pointed out the +particulars of the process, he has made a very important, though not the +most brilliant improvement in this line of business. Mr. WINSOR's +publications are, perhaps, but ill adapted to promote his cause; and the +exaggerated calculation which the sanguine mind of a discoverer is +naturally disposed to indulge in, have, to superficial observers, thrown +an air of ridicule and improbability on the whole scheme of lighting +with gas. + +It may, however, be safely affirmed, that if the same facts had come +forward, under the sanction of some great name in the chemical or +philosophical world, the public incredulity would long since have been +subdued; and the plan, which for many years has been struggling for +existence, would have been eagerly adopted as a national object. + +On the 18th of May, 1804, Mr. FREDERICK ALBERT WINSOR, took out a patent +for combining the saving and purifying of the inflammable gas (for +producing light and heat), the ammonia, tar, and other products of +pit-coal, with the manufacture of a superior kind of coke (see +Repertory, 2d Series, v. 172). And, lately, the same gentleman has taken +out a second patent, for further improvements in these processes. + +In the year 1805, Mr. NORTHERN, of Leeds, also directed the attention +of the public to the application of coal-gas, as a substitute for tallow +light, as will be seen by the following extract of the Monthly Magazine +for April, 1805. + +"I distilled in a retort, 50 ounces of pit-coal in a red heat, which +gave 6 ounces of a liquid matter covered with oil, more or less fluid as +the heat was increased or diminished. About 26 ounces of cinder remained +in the retort; the rest came over in the form of air, as it was +collected in the pneumatic apparatus. I mixed part of it with +atmospherical air, and fired it with the electric spark with a tolerable +explosion, which proves it to be hydrogene.--Whether any of the other +gases were mixed with it, I did not then determine. In the receiver I +found a fluid of an acid taste, with a great quantity of oil, and, at +the bottom, a substance resembling tar. + +"The apparatus I make use of for producing light is a refiner's +crucible, the top of which (after filling with coal) I close with a +metal cover, luted with clay or other luting, so as to prevent the +escape of the gas; a metal pipe is soldered into the cover, bent so as +to come under the shelf in the pneumatic trough, over which I place a +jar with a stop-cock and a small tube; the jar being previously filled +with water, the crucible I place on the common or other fire as is most +convenient; and as the heat increases in it, the gas is forced rapidly +through the water into the jar, and regularly displaces it. I then open +the cock and put fire to the gas, which makes its escape through the +small tube, and immediately a most beautiful flame ensues, perfectly +free from smoke or smell of any kind. A larger light, but not so vivid +or clear, will be produced without passing the gas through water, but +attended with a smoke somewhat greater than that of a lamp charged with +common oil. + +"I have great hopes that some active mechanic or chemist will, in the +end, hit on a plan to produce light for large factories, and other +purposes, at a much less expence, by the above or similar means, than is +at present produced from oil." + +Soon afterwards, Mr. SAMUEL CLEGG[14] of Manchester, Engineer, +communicated an account of his method of lighting up manufactories with +gas-light to the Society of Arts, for which he received the silver +medal. + + [14] This gentleman is at present engineer to the Gas-Light Company. + +Since that time, the application of gas-light has spread rapidly, and +numerous manufactories and other establishments have been lighted by +coal-gas. + +In France, the application of gas-lights to economical purposes, was +pointed out long before it was publicly introduced into this country. M. +LE BON had a house fitted up in Paris, in the winter of 1802, so as to +be entirely illuminated by gas-lights, which was seen by thousands with +admiration; and had a _brevet d'invention_ (patent) granted to him by +the French government, for the art of producing light from wood, ignited +in close vessels. + +Many other attempts have been made to derive advantage from the +different ingredients of coal; but they are too obscure to merit +particular enumeration. + +In the year 1808, Mr. MURDOCH presented to the Royal Society his account +of the application of gas-light, and was complimented with Count +ROMFORD's medal for the same. + +The following statement is taken from Mr. MURDOCH's paper. + +"The whole of the rooms of the cotton mill of Mr. LEE, at Manchester, +which is I believe the most extensive in the United Kingdom, as well as +its counting-houses and store-rooms, and the adjacent dwelling house of +Mr. LEE, are lighted with the gas from coal. The total quantity of light +used during the hours of burning has been ascertained, by a comparison +of shadows, (_see page 23_) to be about equal to the light which 2500 +mould candles, of six to the pound, would give; each of the candles with +which the comparison was made consuming at the rate of 4-10ths of an +ounce (175 grains) of tallow per hour. + +"The gas-burners are of two kinds: the one is upon the principle of the +Argand lamp, and resembles it in appearance; the other is a small curved +tube with a conical end, having three circular apertures or +perforations, of about a thirtieth of an inch in diameter, one at the +point of the cone, and two lateral ones, through which the gas issues, +forming three divergent jets of flame, somewhat like a fleur-de-lis. The +shape and general appearance of this tube has procured it, among the +workmen, the name of the cockspur burner. + +"The number of burners employed in all the buildings amounts to 271 +Argand, and 653 cockspurs, each of the former giving a light equal to +that of four candles of the description above-mentioned; and each of the +latter a light equal to two and a quarter of the same candles; making +therefore the total of the gas-light a little more than equal to that of +2500 candles, six to the pound. When thus regulated, the whole of the +above burners require an hourly supply of 1250 cubic feet of the gas +produced from cannel-coal; the superior quality and quantity of the gas +produced from that material having given it a decided preference in this +situation over every other coal, notwithstanding its higher price. + +"The time during which the gas-light is used may, upon an average of the +whole year, be stated at least at two hours per day of 24 hours. In some +mills, where there is over work, it will be three hours; and in the few +where night work is still continued nearly 12 hours. But taking two +hours per day as the common average throughout the year, the consumption +in Messrs. Philips and Lee's mill will be 1250 × 2 = 2500 cubic feet of +gas per day; to produce which 700 weight of cannel-coal is required in +the retort. The price of the best Wiggan cannel-coal (the sort used) is +13-1/2_d._ per cwt. (22_s._ 6_d._ per ton) delivered at the mill, or say +about eight shillings for the seven hundred weight. Multiplying by the +number of working days in the year (313,) the annual consumption of coal +will be 110 tons, and its cost 125_l._ + +"About one-third of the above quantity, or say forty tons of good common +coal, value ten shillings per ton, is required for fuel to heat the +retorts, the annual amount of which is 20_l._ + +"The 110 tons of cannel-coal, when distilled, produce about 70 tons of +good coke, which is sold upon the spot at 1_s._ 4_d._ per cwt. and will +therefore amount annually to the sum of 93_l._ + +"The quantity of tar produced from each ton of cannel-coal is from 11 to +12 ale gallons, making a total annual produce of about 1250 ale gallons, +which not having been yet sold, it cannot yet be determined its value. + +"The interest of the capital expended in the necessary apparatus and +buildings, together with what is considered as an ample allowance for +wear and tear, is stated by Mr. LEE at about 550_l._ per annum, in which +some allowance is made for this apparatus being made upon a scale +adequate to the supply of a still greater quantity of light, than he has +occasion to make use of. + +"Mr. LEE is of opinion that the cost of attendance upon candles would be +as much, if not more, than upon the gas apparatus; so that, in forming +the comparison, nothing need be stated upon that score, on either side. + +"The economical statement for one year, then, stands thus: + + Cost of 110 tons of cannel coal £ 125 + + Ditto of 40 tons of common ditto, to carbonise 20 + ---- + In all 145 + ---- + Deduct the value of 70 tons of coke 93 + + The annual expenditure in coal, after deducting the value of the + coke, and without allowing any thing for the tar, is therefore 52 + + And the interest of capital sunk, and wear and tear of apparatus 550 + + Making the total expence of the gas apparatus per annum, about 600 + +"That of candles, to give the same light, would be about 2000_l._ For +each candle, consuming at the rate of 4-10ths of an ounce of tallow per +hour, the 2500 candles burning, upon an average of the year, two hours +per day, would, at one shilling per pound, the present price, amount to +nearly the sum of money above-mentioned. + +"If the comparison were made upon an average of three hours per day, as +in most cases, would perhaps be nearer to the truth, and the tear and +wear remaining nearly the same as on the former case, the whole cost +would not exceed 650_l._ while that of the tallow would be 3000_l._" + +Mr. ACKERMAN in this metropolis, has shown that the art of gas-light +illumination is not confined to great manufactories, but that its +advantages are equally applicable to those on a moderate scale. The +whole of Mr. ACKERMAN's establishment, his public library, warehouse, +printing-offices and work-shops, together with his dwelling house, from +the kitchen to the drawing-room, has, for these four years past, been +lighted with gas, to the total exclusion of all other lights. The result +of the whole of this proceeding will be obvious from the following +letter: + + To MR. ACCUM. + + SIR, + + "In answer to your request with regard to my gas-lights, which I now + have in my house, I take this mode of informing you, that I charge two + retorts with 240lbs. of coal, half cannel and half Newcastle, from + which I extract 1000 cubic feet of gas. To obtain this quantity of + gas, when the retorts are cold, I use from 100 to 110lb. of common + coals; but when they are in a working state, that is to say, when they + are once red hot, the carbonising fuel amounts to about 25lb. per + retort. The bulk of gas thus obtained supplies 40 Argand's lamps, of + the large size, for four hours per night, during the long winter + evenings, together with eight Argand's lamps and about 22 single + cockspur burners, for three hours per night: in addition to which my + printers employ 16 cockspur burners for ten hours per day to heat + their plates instead of charcoal fire. In the depth of winter we + charge two retorts per day: but, upon an average, we work 365 retorts + in 365 days. + + Now 365 retorts containing 120lb. of coal each, make 43800lb. which is + equal to ten chaldrons of Newcastle and eight tons of cannel coal. + + 10 chaldrons of Newcastle coals, at 65s. make £ 32 10 0 + 8 tons of cannel coal,[15] (this coal is sold by weight) + at 100s. per ton 40 0 0 + 7 chaldrons of common coals for carbonising, at 55s. 19 5 0 + To wages paid the servant for attending the gas apparatus 30 0 0 + Interest of money sunk 30 0 0 + The wear and tear of the gas-light apparatus I consider to + be equal to the wear and tear of lamps, candlesticks, &c. + employed for oil, tallow, &c. ----------- + Total expence of the gas lights 151 15 0 + + DEDUCT + + 23 chaldrons of coke, at 60s. per chaldron 69 + Ammoniacal liquor 5 + Tar 6 + Charcoal employed by the copper-plate printers to + heat their plates, which is now done with the gas- + light flame, cost, annua 25 + Two chaldrons of coals _minus_ used as fuel, for + warming the house, since the adoption of the gas- + lights, at 65s. per chaldron 6 10 + ------ 111 10 0 + ---------- + Nett expences of the gas-lights £ 40 5 0 + ---------- + The lights used in my Establishment, prior to the gas- + lights, amounted annually to 160 0 0 + My present system of lighting with gas costs, per ann. 40 5 0 + ---------- + Balance in favor of the gas for one year £ 119 15 0 + + Such is the simple statement of my present system of lighting, the + brilliancy of which, when contrasted with our former lights, bears the + same comparison to them as a bright summer sun-shine does to a murky + November day: nor are we, as formerly, almost suffocated with the + effluvia of charcoal and fumes of candles and lamps. In addition to + this, the damage sustained by the spilling of oil and tallow upon + prints, drawings, books and paper, &c. amounted annually to upwards of + 50l. All the workmen employed in my establishment consider their + gas-lights as the greatest blessing; and I have only to add, that the + light we now enjoy, were it to be produced by means of Argand's lamps + or candles, would cost at least 350l. per annum. + + I am, with respect, + + Yours, + + Strand, March 13, + + 1815. + + R. ACKERMAN." + + [15] _Although cannel-coal sells at nearly double the price of + Newcastle coal, I use it in preference to the latter, because it + affords a larger portion of gas, and gives a much more brilliant + light._ + +Another manufacturer who was one of the first that adopted the use of +this method of illumination in the small way, and who gave a statement +of its advantages to the public, is Mr. COOK, a manufacturer of metal +toys, at Birmingham, a clear-headed, prudent man, not apt to be dazzled +by a fanciful speculation, but governed in his transactions by a simple +balance of profit and loss. There is a _naïveté_ in his own account of +the process which will amuse as well as instruct the reader. + +"My apparatus is simply a small cast-iron pot, of about eight gallons, +with a cast-iron cover, which I lute to it with sand. Into this pot I +put my coal. I pass the gas through water into the gasometer or +reservoir, which holds about 400 gallons; and, by means of old +gun-barrels, convey it all round my shops. Now, from twenty or +twenty-five pounds of coal, I make perhaps six hundred gallons[16] of +gas; for, when my reservoir is full, we are forced to burn away the +overplus in waste, unless we have work to use it as it is made: but, in +general, we go on making and using it, so that I cannot tell to fifty or +a hundred gallons;--and, in fact, a great deal depends on the coals, +some coals making much more than others. These twenty-five pounds of +coal put into the retort, and say twenty-five pounds more to heat the +retort, which is more than it does take one time with another, but I am +willing to say the utmost, are worth four-pence per day. From this +four-pence we burn eighteen or twenty lights during the winter season." + + [16] A wine-gallon is equal to 231 cubic inches. + +Thus are the candles which Mr. COOK used to employ, and which cost him +three shillings a day, entirely superseded. But, besides his expence in +candles, oil and cotton for soldering, used to cost him full 30_l._ a +year; which is entirely saved, as he now does all his soldering by the +gas flame only. For "in all trades in which the blow-pipe is used with +oil and cotton, or where charcoal is employed to produce a moderate +heat, the gas flame will be found much superior, both as to quickness +and neatness in the work: the flame is sharper, and is constantly ready +for use; while, with oil and cotton or charcoal, the workman is always +obliged to wait for his lamp or coal getting up; that is, till it is +sufficiently on fire to do his work. Thus, a great quantity of oil is +always burned away useless; but, with the gas, the moment the stop-cock +is turned, the lamp is ready, and not a moment is lost." We must refer +to Mr. COOK's letter for the details of expence, which he gives with +faithful minuteness, and always leaning to the side unfavourable to the +gas. The result of the whole is, that he saves 30_l._ out of the 50_l._ +which his lights formerly cost him: and, when we consider that his +calculation allows the gas-lights to burn the whole year, and the +candles only twenty weeks, there can be little doubt, that the savings +in this case follow nearly the same proportion as in the former. If the +apparatus be erected even on a smaller scale, "the saving," Mr. COOK +assures us, "will still be considerable: for the poor man, who lights +only six candles, or uses one lamp, if the apparatus is put up in the +cheapest way possible, will find it only cost him 10_l._ or 12_l._ which +he will nearly, if not quite, save the first year." + +Mr. ACKERMAN having, in this town, set the example of lighting his +establishment with gas, several other individuals soon followed the +attempt. The following statement will show, that this species of light +may be made use of with the greatest advantage, upon a still smaller +scale, where no great nicety with regard to the apparatus for procuring +gas is required. The following report I have received from Messrs. +LLOYD, of Queen Street, Southwark, thimble manufacturers and +whitesmiths, who have used the gas-light for soldering and other +purposes these five years past. + + From 4 pecks or 1 bushel of coals, weighing 69lbs. for + which we now pay (1809) 1s. we produce 4-3/4 pecks of + coke and 1/2 peck of coal not carbonised remains in the + distilling pot, which together with the coke weighs + 58lbs. 6 oz. value at 1s. per bushel 0 1 4 + we procure 6lbs. 4 oz. of tar which we use as pith--it + saves us 0 1 0 + ---------- + 0 2 4 + Deduct for coal 0 1 0 + ---------- + Profit on coke and tar 0 1 0 + ---------- + The gas yielded by the 4 pecks of coals in the pot, make + 42 brilliant lights, which burn 7 hours. To keep 42 + tallow candles which were formerly used in the manufactory + burning for the same time, required 7lbs. which at 1s. per + lb. cost 0 7 0 + To this, add profits on coke and tar 0 1 0 + ---------- + Gained out of every bushel of coal 0 8 0 + ---------- + +"The gas-burners made use of in our manufactory produce jets of flame, +which in our business, where much soldering with the blow-pipe must be +done, have a decided superiority over Argand's lamps. We are not nice +concerning the quality of the gas--a great part of it is burned from the +gasometer, without allowing it to purify itself in the gasometer, +because our gasometer is not large enough to store up the whole quantity +of gas we want for use." + + +THEORY OF THE PRODUCTION OF GAS-LIGHT, AND DESCRIPTION OF A PORTABLE +APPARATUS FOR EXHIBITING, IN THE SMALL WAY, THE GENERAL NATURE OF THIS +SPECIES OF LIGHT. + +To obtain carburetted hidrogen, or coal-gas, from common pit-coal, and +to apply it for the purposes of illumination, the coal is introduced +into large iron cylinders, called retorts, to the apertures of which +iron pipes are adapted, terminating in a vessel, or vessels, destined to +purify and collect the gas. The retorts charged with coals and made +air-tight, are placed upon the fire, the action of which extricates the +gazeous products from the coals, together with an aqueous ammoniacal +vapour, and a tenaceous bituminous fluid, or tar, &c. The liquid +substances are conveyed into proper vessels, and the gazeous products +are conducted, by means of pipes, under the gasometer, where the gas is +again washed, and remains ready for use. There are also other pipes +leading from the gasometer, which branch out into smaller ramifications, +until they terminate at the places where the lights are wanted. The +extremities of the pipes have small apertures, out of which the gas +issues, and the streams of gas being lighted at those apertures burn +with a clear and steady flame as long as the supply of gas continues. +All the pipes which come from the gasometer are furnished at their +extremities with stop-cocks to regulate the admission of the gas. The +burners are formed in various ways, either a tube ending with a simple +orifice, at which the gas issues in a stream, and if once lighted will +continue to burn with the most steady and regular light imaginable, as +long as the gas is supplied; or two concentric tubes of brass, or +sheet-iron, are placed at a distance of a small fraction of an inch from +each other, and closed at the bottom. The gas which enters between these +cylinders, when lighted, forms an Argand lamp, which is supplied by an +internal and external current of air in the usual manner. Or the two +concentric tubes are closed at the top with a ring having small +perforations, out of which the gas alone can issue, thus forming +small distinct streams of light. + +[Illustration] + +The gas-apparatus, plate 2, will be found very convenient for +exhibiting, in the small way, the general nature of this new art of +illumination, whilst at the same time it may serve to ascertain, at a +trifling expence, the comparative value of different kinds of coals +intended to be employed for the production of this species of light, as +well as other occasional purposes connected with the gas-light system of +illumination. + +It consists of three distinct apparatus:--namely, a portable furnace, +fig. 1, plate 2, by means of which the gas is prepared--fig. 2, a +purifyer, or condenser, which separates and purifies the products +obtained from the coal, so as to render the gas fit for the purpose of +illumination--fig. 3, a gasometer, or reservoir for receiving and +preserving the purified stock of gas, and from which it may be +transferred and distributed as occasion may require. The following +statement will explain more fully the general nature of this portable +chamber apparatus:--_a_, represents a cast iron retort, such as is used +for chemical operations in the small way. This retort rests upon a +tripod of hammered iron, placed upon the bars of the grate of the +chemical furnace. Into this retort the coals are put for furnishing the +gas. It is provided with a solid iron stopper ground air-tight into the +mouth of the retort, and the stopper is secured in its place by an iron +wedge passing over it in the centre; by means of which the mouth of the +retort when charged with coal is readily made air-tight, and the stopper +may easily be removed by knocking out the iron wedge. _b._ is a metal +pipe which conveys all the distillatory products from the retort into +the purifier fig. 2. This tube is bent at right angles at the extremity +where it enters the intermediate vessel fig. 2. The purifier fig. 2, is +divided into three compartments marked _c._ _d._ _e._ The first +compartment is filled with water, and by means of it an air-tight +communication is established with the retort which furnishes the gas. +The second compartment, _d_, contains a solution of caustic pot-ash +composed of about 2 parts of caustic pot-ash and 16 of water, or a +mixture of quick-lime and water of the consistence of very thin cream. +The object of this compartment is to separate the non-inflammable gases +and other products evolved during the distillation of the coal, from the +carburetted hidrogen or coal-gas, so as to render it fit for use. The +third compartment _e_ is left empty to receive the tar and other liquid +products. Into the first compartment _c_, all the gazeous and liquid +products are delivered, as they become evolved during the distillation, +by means of the pipe _b_. The compartment _d_, of the purifier, or +alcali vessel, is furnished with a wide perpendicular pipe, which serves +to make an air-tight communication with the retort, by allowing the tube +_b_, to pass readily through it. From the chamber _c_, the liquid and +gazeous products pass to the tar-chamber, or compartment _e_, by means +of the descending pipe _f_. The tar and other condensible substances are +therefore deposited at _e_, whilst the gazeous products alone ascend +from the tar-chamber _e_, by the pipe _g_, and down again the pipe _h_, +(which is closed at the top) into the compartment _d_, of the vessel or +purifier, fig. 2. The gas being thus made to pass from the compartment +_e_, up into the pipe _g_, and down the pipe _h_, (which is closed at +the top) into the purifier _d_, is brought into contact with the liquor +in that vessel, where it is opposed to a pressure in proportion to the +perpendicular height of the column of liquid which it contains. The +funnel in the compartment _c_, is considerably higher than the purifying +apparatus, it therefore allows the liquid which it contains, when +pressed upon by the gas, to ascend into it, without overflowing the +apparatus, and to descend again as the pressure diminishes--_i_ is +another wide-mouth funnel, by means of which the chamber _d_, is filled +with the alcaline solution, or mixture of lime and water. The carbonic +acid gas and sulphuretted hidrogen, evolved during the distillation of +the coal, are thus made to combine with the alcali or lime, in the +compartment _d_, of the purifier, forming carbonate and hidro-sulphuret +of lime. The carburetted hidrogen, being left more or less pure, is +conveyed through the pipe _k_, into the gasometer, fig. 3. The +communication of the purifier, fig. 2, with the gasometer, is made by +means of the well-known water-valve _l_, placed so that the +communicating tube _k_, may be easily removed at pleasure--_m_, is a +cock for drawing off the tar, &c. _n_, a gauge-cock for ascertaining the +height of the liquid in the chamber _d_. The gasometer, fig. 3, the +object of which is to store up the gas, consists of two principal +parts--namely, a large interior vessel designed to contain the gas, and +an outer cistern or vessel, of rather greater capacity, in which the +former is suspended, designed to contain the water by which the gas is +confined. The interior vessel which contains the gas is suspended by +chains or cords hung over pullies, to which weights are attached, so as +to nearly equipoise it. _o_ is a pipe, which communicates with the +water-valve _l_, and by means of which the gas passes from the purifier, +fig. 2, into the gasometer. The upper end of this pipe is covered, in +the manner of a hood, by a cylindrical vessel _p_, open at bottom, but +partially immersed beneath the surface of the water contained in the +outer cistern of the gasometer, and perforated round near the lower edge +with a number of small holes. The gas displaces the water from this +receiver _p_, and escapes through the small holes, rising in bubbles +through the water, so as to expose a large surface to its action, that +it may be properly washed, &c. After rising through the water the gas +enters the gasometer, which is suspended to move up and down by the +chains, pullies, and balance-weights, _q_. From the centre of the +gasometer a tube, _r_, descends, which includes a pipe, _s_, fixed +perpendicular from the bottom of the cistern. The fixed pipe _r_, forms +a guide to keep the gasometer always perpendicular. _t_ is also an iron +pipe made fast in the centre of the inner vessel, and communicates with +the upright tube, _s_, in the outer vessel. This contrivance obliges the +gas to pass into the pipe _t_, whilst it also serves to keep the +gasometer steady when nearly out of the outer cistern. + +When the operation commences, the gasometer is sunk down nearly to a +level with the surface of the water in the outer cistern, and is +consequently filled with water; but as the gas enters, it rises up to +receive it. It is to be noted, that the balance-weights _q_ _q_, should +not be quite so heavy as the gasometer, in order that some pressure may +be exerted, to force the gas out of the burners with a proper jet. The +gas which issues from the retort enters the purifier as stated already, +and ascends the pipe _o_, into the vessel, _p_, from which it displaces +the water, and passes out at the small holes, as before described, +rising through the water into the gasometer, and raising it up: the gas +then passes away to the burners, _u_ _u_. In this manner the process +proceeds until the whole of the volatile products of the coal in the +retort is evaporated. The use of the gasometer is, to equalize the +emission of the gas which comes from the retort more quickly at some +time than others. When this happens, the interior vessel rises up to +receive it, and when the stream from the retort diminishes, the weight +of the gasometer expels its contents. When the process is finished, the +retort is suffered to cool, and its ground stopper is then removed to +replenish it with coal. The residue found in the retort is coke. _v_ _v_ +are cocks to let off any liquid that may collect in the pipe _o_ or _t_; +for if the smallest portion of liquid were to obstruct the free passage +of the gas to the burners, the consequence would be, that the lights +would not burn steadily--they would, as it is called, _dance_, or become +extinguished. _x_ is the main stop-cock which communicates with the +burners--these, of course, may be placed as convenience may require. _z_ +_z_ are two projecting parts in the top of the gasometer; they are +intended to receive the hood _p_, and the upper extremity of the pipe +_t_, so as to allow the gasometer to be wholly immersed into the +cistern. The wheels or pullies of the gasometer have a groove to allow +the links of the chain to pass freely. + +In this apparatus there is no provision made for the unequal pressure +which the gas suffers, accordingly as the gasometer is more or less +immersed in water. It will be observed that, in this apparatus, the +weight of the interior vessel is constantly increasing, in proportion as +it fills with gas, and rises out of the water, and consequently, if a +constant, uniform, counterpoising weight, equal only to that of the +gasometer in the first moment of its rise, be employed, the gas becomes +gradually more and more compressed by that part of the weight of the +gasometer which is not counterpoised, and if its pressure or quantity be +then estimated by the bulk which it occupies, without making allowance +for the increasing pressure, a material error must arise, and this, in +the large way, would give rise to insurmountable difficulties with +regard to the regulation of the size of the flames; which could not be +rendered uniform. + +Suppose the cistern or exterior vessel full of water, and the gasometer +partly filled with gas and partly with water, it is evident that the +balance-weight may be so adjusted, as to occasion an exact equilibrium, +so that the external air shall not tend to enter into the gasometer nor +the gas to escape from it; and in this case the water will stand exactly +at the same level both within the gasometer and within the outer +cistern. On the contrary, if the balance-weights be diminished, the +gasometer will then press downwards from its own gravity, and the water +will stand lower in the gasometer than it does in the cistern; in this +case, the included air or gas will suffer a degree of compression above +that experienced by the external air, exactly proportioned to the weight +of a column of water, equal to the difference of the external and +internal surfaces of the water. + +To compensate for this increasing weight of the gasometer, and render a +scale of equal graduations accurate, some have ingeniously adopted the +plan of a spiral pulley to the chain, which has the effect of gradually +avoiding the evil, but the best way of accomplishing it will be stated +hereafter. + +With regard to the philosophy or the production of coal-gas, it proves +that pit-coal contains solid hidrogen, carbon, and oxigen. When the +intensity of the heat has reached a certain degree, a part of the carbon +unites with part of the oxigen and produces carbonic acid, which by +means of caloric is melted into the gazeous state and forms carbonic +acid gas; at the same time, part of the hidrogen of the coal combines +with another portion of carbon and caloric, and forms the carburetted +hidrogen gas, which varies considerably in its constitution, according +to the circumstances under which it is produced; a portion of olifiant +gas, carbonic oxid, hidrogen, and sulphuretted hidrogen, is also +produced during the process. The quantities of these products vary +according to the nature of the coal employed in the process. + +Pit-coal is not the only substance which affords carburetted hydrogen; +this gazeous fluid may be obtained in a great variety of ways, and with +very considerable differences in specific gravity and proportion of +ingredients. + +It is found plentifully native or ready formed on the surface of +stagnant waters, marshes, wet ditches, &c. through which, if examined +closely, large bubbles will be seen to rise in hot weather, and may be +increased at pleasure by stirring the bottom or mud with a stick. + +In close still evenings if a lighted candle is held over the surface, +flashes of blue lambent flame may sometimes be perceived spreading to a +considerable distance. All that is not fabulous concerning the _ignis +fatuus_ is probably derived from this source. This species of gas is +termed for distinction the carburetted hydrogen of marshes. In the +purest form in which it can be collected it is mixed with about 20 per +cent. of azot or nitrogen. + +To procure the gas for the purpose of philosophical amusement, fill a +wide-mouthed bottle with the water of the ditch, and keep it inverted +therein with a large funnel in its neck, then with a stick stir the mud +at the bottom just under the funnel, so as to cause the bubbles of air +which rise from the mud to enter into the bottle; when by thus stirring +the mud in various places, the air may be catched in the bottle. + +Carburetted hidrogen gas is also given out very abundantly by all kinds +of vegetable matter when subjected to a scorching heat sufficient to +decompose them. When heated in close vessels much more gas is obtained +than when burnt in the open air. If moistened charcoal be put into an +earthen retort and heat be applied till the retort becomes ignited; gas +will be evolved, consisting partly of carbonic acid, and partly of +carburetted hidrogen. A gas of similar properties is obtained by causing +steam to pass through a tube filled with red-hot charcoal; by passing +spirit of wine, or camphor, through red-hot tubes; by distilling oils, +wood, bones, wax and tallow, or any animal or vegetable body whatever. + +Indeed it would be endless to enumerate the various sources of this +gazeous fluid. A most curious variety of carburetted hidrogen gas has +been discovered by the associated Dutch chemists (VAN DIEMAN, +TROOSTWYCK, and others) which is procured from ether or alcohol, and has +the remarkable property of generating a heavy oil when in contact with +chlorine gas. Hence it has been termed oily carburetted hidrogen, or +olifiant gas--it consists of carburetted hydrogen, supersaturated with +carbon. The oil generated is heavier than water, whitish, and +semi-transparent. By keeping, it becomes yellow and limpid; its smell is +highly fragrant and penetrating--its taste somewhat sweet--it is partly +soluble in water, imparting to it, its peculiar smell. A portion of this +gas always accompanies the common carburetted hidrogen obtained from +coal, and those sorts of coal that afford the largest quantity of it are +best suited for the production of gas-light. + +The nature of carburetted hidrogen obtained from coal varies +considerably according to the conditions under which it is obtained. The +first part is always much heavier than the last, though still lighter +than common air, and holds in solution a portion of oil, for on standing +for some time over water it becomes lighter, and is found to require +less oxygen for saturation than before. The oil which it held suspended, +then becomes precipitated. The average specific gravity of the first and +last gas mixed, which may be taken as an average of the whole specific +gravity is to that of common air as 2 to 3--112lb. of common cannel +coal produce at its _minimum_, from 350 to 360 cubic feet of carburetted +hidrogen gas; but the same quantity of the best Newcastle coal, that is +to say, such as coke, which, when laid on the fire readily undergoes a +kind of semi-fusion, and sends out brilliant streams of flame, produces +upon an average from 300 to 360 cubic feet of this gazeous fluid, +besides a large portion of sulphuretted hidrogen, carbonic oxid and +carbonic acid. Half a cubic foot of this carburetted hidrogen, fresh +prepared, that is to say, holding in solution or suspension, a portion +of the essential oil, which is generated during the evolution of the +gas, is equal in illuminating power to from 170 to 180 grains of tallow, +(being the quantity consumed by a candle six to the pound in one hour.) +Now, one pound avoirdupoise is equal to 7000 grains, and consequently +one pound of candles of six in the pound, burning one at a time in +succession, would last (if we take 175 grains of tallow to be consumed +in an hour) 7000/175 = 40 hours. To produce the same light we must burn +one half of a cubic foot of coal-gas per hour; therefore, one-half +multiplied by forty hours is equal to twenty cubic feet of gas in 40 +hours, consequently equal to one pound of candles, six to the pound, +provided they were burnt one after another. One hundred and twelve +pounds of cannel-coal, produce, at its _minimum_, three hundred and +fifty cubic feet of gas; and are equal to three hundred and fifty, +divided by twenty, which last is equivalent to one pound of tallow, +making one hundred and twelve pounds of cannel-coal, equal to 350/20 = +17-1/2lbs. of tallow. Further, one hundred and twelve pounds of +cannel-coal, divided by seventeen and a half of tallow make six and +four-tenths of cannel-coal, equal to one pound of tallow. + +With regard to Newcastle coals[17], it may be stated that one chaldron +of Wall's-End coal may be made to produce in the large way upwards of +11,000 cubic feet of crude gas; which, when properly purified, +diminishes to nearly 10,000 cubic feet. + + [17] One chaldron of Newcastle coal weighs from 2850 to upwards of + 2978lb. + +The production of carburetted hydrogen, both with regard to quantity and +quality from the same kind of coal depends much upon the degree of +temperature employed in the distillatory process. If the tar and oil +produced during the evolution of the gas in its nascent state, be made +to come in contact with the sides of the red hot retorts, or if it be +made to pass through an iron cylinder or other vessel heated red hot, a +large portion becomes decomposed into carburetted hydrogen gas and +olifiant gas, and thus a much larger quantity of gas is produced than +would be obtained without such precaution from the same quantity of +coal.[18] + + [18] One pound of coal-tar produces 15 cubic feet of carburetted + hidrogen abounding in olifiant gas. + +The distillation of the coal, (if gas be the chief object) should +therefore not be carried on too rapidly. Most of the retorts used in the +large way, are calculated for containing about one hundred weight of +coal, and in general, when previously heated, produce from two and +one-half to three cubic feet of gas, in four hours for each pound of +coal they contain; but when the layer of coals in them does not exceed +four inches in depth, three and one-half to four feet of gas may be +obtained in the same time. + +The retorts best calculated for large gas-light works are seven or eight +foot long (without the mouth-piece) and twelve inches in diameter, +tapering down to ten inches--if they are larger the coal which they +contain cannot be heated properly. The advantages that may be derived +from the circumstances before stated are of greater value in the +gas-light manufacture than is often imagined, and the quantity as well +as the quality of the gas is very much influenced by such circumstances. +If coal be distilled with a very low red heat scarcely observable by +daylight, the gas produced gives a feeble light--if the temperature be +increased so that the distillatory vessel is of a dull redness, the +light is more brilliant and of a better colour--if a bright or +cherry-red heat be employed the gas produced, burns with a brilliant +white flame, and if the heat be increased so far that the retort is +almost white hot, and consequently in danger of melting, the gas given +out, has little illuminating power, and burns with a clear blueish +flame;[19] or if the coal abounds in pyrites or sulphuret of iron, as is +sometimes the case with Newcastle coal, a large quantity of sulphuretted +hidrogen is likewise evolved, which although it increases the +illuminating power of the coal-gas, has the capital disadvantage, of +producing an intolerable suffocating odour, when the gas is burnt which +is particularly perceptible in low rooms illuminated with such gas. + + [19] It is chiefly a mixture of carbonic oxid, and hydrogen gas. + +These observations also apply to the distillation of tar, which when +distilled either in a vaporous or nascent state, during its first +production from coal in the ordinary process, or if it be submitted to a +second distillation, mingled with a fresh portion of pit-coal, a +practice usually had recourse to when this product cannot be disposed of +more advantageously. The best depth of coal in the retort for procuring +excellent gas, and at the same time for yielding the greatest quantity +from the same weight in the shortest possible time, is about six inches. + +The brightness of the coal-gas flame is rather diminished when the gas +has been long kept over water, and hence for illumination it should be +used as soon as prepared, but of course properly purified. + +The quantity of gas taken up by water is affected by temperature, +because the temperature increases its elasticity; the quantity of gas +absorbed, diminishes as the temperature increases, and increases as the +temperature diminishes. 1/27 part of its own bulk of pure coal-gas is +absorbed by the water over which it is confined in the gazometer. + +The chemical constitution of this gazeous fluid is best ascertained by +burning it in a vessel of oxygen gas, over lime-water in a pneumatic +reservoir, by means of a bladder and bent brass pipe. Two products are +then obtained, viz. water and carbonic acid. That water is produced, may +be shown by burning a very small stream of the gas in a long +funnel-shaped tube open at both ends. The formation of carbonic acid is +evinced, by the copious precipitation of the lime-water in the foregoing +experiment. + +If carburetted hydrogen be mixed with a sufficient quantity of oxygen +gas or common air and fired by the electric spark, or by any other +method, an explosion takes place more or less violent according to the +quantity of carbonaceous matter condensed in the hydrocarbonat; and the +remaining gas consists of carbonic acid, together with any unconsumed +gas, or excess of oxygen, whilst the water condenses in drops on the +sides of the vessel. A few cubic inches of the mixed airs is as much as +can be conveniently managed at a single explosion; and when any portion +of olefiant gas is present, even this quantity will endanger very thick +glass jars. A very vivid red flame appears at the moment of the +explosion, and a great enlargement takes place in an instant, after +which the bulk is suddenly reduced to much less than the original +quantity. When the carbonic acid is absorbed by lime-water, if the +gasses have been properly proportioned, no gazeous residue is left, +except accidental impurities. Though carburetted hydrogen gas, is +sometimes naturally produced in coal-mines, and occasionally mixes with +common air, producing dreadful explosions, yet when coal-gas is mixed +with common air, it does not explode unless the gas be to the air as 1 +to 10 nearly. Such are the leading chemical habitudes of this gazeous +product. The varieties of carburetted hydrogen gas all agree in being +inflammable; but they possess this property in various degrees, as is +evinced by the variable brightness of the flame which they yield when +set on fire. + +"Messrs. SOBOLEWSKY and HORRER, of St. Petersburgh, have employed wood +for the purpose of producing carburetted hydrogen gas. The pyroligneous +acid obtained in this operation, when freed from the empyreumatic oil +with which it is mixed, becomes acetous acid, and is applicable to all +the uses of vinegar. A cubic cord of wood equal to 2.133 French metres +(a metre being rather more than an English yard), yields 255 Paris +pounds of charcoal, and 70 buckets of acid. The latter gives 30 pounds +of tar, after the extraction of it 50 buckets of good vinegar remain. +The same quantity of wood furnishes 50,000 cubic feet of gas, sufficient +for the supply of 4000 lamps for five hours."[20] + + [20] See Repository of Arts, Vol. XI. No. 36, p. 341. + + +UTILITY OF THE GAS-LIGHT ILLUMINATION, WITH REGARD TO PUBLIC AND PRIVATE +ECONOMY. + +From what has been stated in the preceding pages it becomes obvious, +that a substance yielding an artificial light may be obtained from +common coal in immense quantities. The attempt to derive advantage from +so valuable a discovery is surely no idle speculation. Let us therefore +now consider to what objects of public and private utility this mode of +procuring light may be applied with effect. It is obvious that coal-gas +may be preserved in a reservoir for any length of time and that it may +be conveyed by means of tubes to any distance flowing equably and +regularly like water. Those, indeed, who have not seen the contrivance +will find it difficult to imagine with what ease it is managed. The gas +may be distributed through an infinity of ramifications of tubes with +the utmost facility. Near the termination of each of the tubes through +which it flows, it is confined by a valve or stop-cock, upon turning +which, when required to be lighted, it flows out in an equable stream +and ascends by its specific levity. There is nothing to indicate its +presence; no noise at the opening of the stop-cock or valve--no +disturbance in the transparency of the atmosphere--it instantly bursts +on the approach of a lighted taper, into a brilliant, noiseless, steady +and beautiful flame. Its purity is attested by its not blacking or +soiling in the least degree the metallic orifice from which it issues, +nor even a sheet of white paper, or polished surface brought in contact +with it. There is no escape of combustible matter unconsumed, which is +so great a nuisance in all our common lights. The products of the +combustion are water and carbonic acid gas[21]. The accurate and elegant +experiments of Dr. W. HENRY have shewn in the most satisfactory manner, +that considerably less carbonic acid is produced by the flame of +coal-gas, than by that of oil, tallow, or wax[22], which sufficiently +refutes the absurd notions that have been circulated respecting the +pernicious effects of gas-lights. But if the gas from Newcastle coal is +badly prepared, or not deprived of the portion of sulphuretted hydrogen, +which it usually contains, it then emits fiery sparks and produces a +portion of sulphureous acid by virtue of the union of the oxygen of the +air with the sulphur dissolved in the gas, the consequence of which is, +a suffocating odour, which is particularly observable in the higher +stratum of the air of apartments in which the gas is burnt. Such gas +likewise tarnishes all metallic bodies--it discolours the paintings +effected with metallic oxids, and always produces a suffocating odour +very noxious to health. It is freed from the sulphuretted hydrogen and +may be rendered fit for illumination by passing it repeatedly through +very dilute solutions of sub-acetate of lead, green sulphate of iron, +quicklime and water, or hyper-oxymuriate of lime. + + [21] The water (which passes off in imperceptible vapour) is generated + by part of the oxygen of the air uniting with part of the hydrogen, + which forms the great bulk of the coal-gas: and the carbonic acid gas + is produced by the union of another portion of the oxygen uniting with + the smaller portion of carbon, which is the other component part of + the coal-gas. + + [22] 100 Cubic inches of carburetted hydrogen from coal, require for + burning 220 cubic inches of oxygen and produce 100 cubic inches of + carbonic acid--100 cubic inches of the same gas obtained from wax, + require for burning 280 cubic inches of oxygen and produce 137 cubic + inches of carbonic acid--100 cubic inches of the same gas procured + from lamp-oil, require 190 cubic inches of oxygen for burning, and + produce 124 cubic inches of carbonic acid. + + The following lines relating to the salubrity of the gas-light + illumination are copied from Mr. Lee's evidence in the House of + Commons, when examined on that subject. + + Question--"Is the health of your manufacturers at all affected by the + use of gas?--Answer--Not in the least, or I would not have adopted it. + I believe I explained to the Committee, that I used the gas-lights in + my own house first." + + Q. "You have not seen the smallest alteration in the health of your + workmen?--A. Not in the least, for had I seen it, it would have been a + fatal objection to it." + + Q. "And you say the same in regard to the use of the gas-lights in + your own family?--A. Certainly I do." + +As to the brilliancy of the flame, an appeal may be made to every one +who has witnessed the gas-light illumination, whether it be not superior +to the best wax candle-light, or the light of Argand's lamps. + +It may be described as a rich compact flame, burning with a white and +agreeable light. It is also perfectly steady, when the flame is limited +to a moderate size: in large masses, it is subject to that undulation +which is common to it with all flames of certain dimensions, and is +caused by the agitation of the surrounding atmosphere. The gas flame is +entirely free from smell. The coal-gas itself certainly has a +disagreeable foetid odour before it is burnt, so has the vapour of wax, +oil, and tallow, as it comes from a lamp or candle newly blown out. This +concession proves nothing against the flame of gas which is perfectly +inodorous, a white handkerchief, passed repeatedly through it and +applied to the nose, excites no odour. + +Another peculiar advantage of the gas flame is, that it may be applied +in any direction we please, as there is nothing to spill and the gas is +propelled by a certain force which is always the same, it will burn +equally well in an almost horizontal as in an upright position; and we +can thus obviate two great objections to all our artificial lights, that +their least luminous end is directed downwards where the light is +generally most wanted, and that a shade is cast below by the stand or +support of the combustible matter. + +The size, shape and intensity of the gas-flame may be regulated by +simply turning a stop-cock which supplies the gas to the burner. It may +at command be made to burn with an intensity sufficient to illuminate +every corner of a room, or so low and dim as barely to be perceived. It +is unnecessary to point out how valuable such lights may be in +nurseries, stables, warehouses, in the chambers of the sick, &c. + +From the facility with which the gas-flame can be conveyed in any +direction, from the diversified application, size and shape which the +flame can be made to assume, there is no other kind of light so well +calculated for being made the subject of splendid illuminations. + +Where lustres are required in the middle of a room, the best mode of +conducting the gas to the chandelier, is to pass the gas-pipe through +the ceiling from the room above, immediately over the lustre. This can +be easily done without injury to the apartment. + +Where side-lights and chandeliers are required the tubes need never +appear in sight, but may be concealed in the wall or floor of the +house. When transparencies are wanted as decorations for halls, lobbies, +&c. more than light, recesses may be filled with different coloured +_media_, or paintings, and any intensity of light may be thrown on the +object. + +If a number of minute holes are made in the end of a gas pipe, it forms +as many _jets de feu_, which have a very brilliant appearance; these may +sometimes be placed in the focus of a parabolic reflector. In cases +where the light is required to be thrown to a distance, other burners +are constructed upon the same principle as the Argand lamp, forming a +cylinder of flame, and admitting a current of air both to the inside and +outside. + +On comparing the flame of a gas-light with the flame of a candle +whatever its size may be, it appears just as yellow and dull as the +flame of a common lamp appears when compared with that of a lamp of +Argand. The beautiful whiteness of gas-light never fails to excite the +surprize and admiration of those who behold it for the first time. + +A large edifice or manufactory lighted by gas, contrasted with one of +the same kind lighted by candles or lamps, resembles a street on the +night of a general illumination, compared with the glimmering light of +its ordinary parish lamps. + +The intensity of one of the parish gas-light lamps, now exhibited in the +streets of this metropolis, will bear ample testimony of this assertion; +the light of the parish gas-lamps, is to the intensity of the parish oil +lamps as 1 to 12. + +One of the most obvious applications of the gas-light illumination +unquestionably consists in lighting streets, shops and houses; and let +it be observed that as this is found safe and economical, it proves all +that the most ardent friends of the gas-light system can desire. For in +contending with the common mode of lighting the streets and shops, the +new lights must beat out of the market the cheapest of all artificial +lights; and as it has succeeded in doing this it shews in the most +satisfactory point of view, the prodigious advantages of gas-lights when +compared with the materials of tallow and oil. + +The original expence of laying the pipes for conveying the gas, together +with the cost of the machinery, is all that is required; the preparation +of the gas being itself a lucrative process, no doubt will pay all its +expences besides the interest of capital, and leave a surplus of profit. + +Indeed the application of the coal-gas, as a substitute for tallow and +oil, to illuminate houses, shops, &c. is no longer problematical, a +considerable extent of this capital, together with numerous shops and +houses being already supplied with this species of light.[23] + + [23] The Liberty of Norton Falgate, as far as Bishopgate-street, is + lighted with gas-light, from the Chartered Company's station at Norton + Falgate; and gas-light pipes are laid from that station as far as the + west end of Cheapside, and in all the streets north of that great + thoroughfare. + + In the West end of the Town, the main pipes for supplying the streets + and houses with light from the Gas-Light Company, extend through the + most eligible parts; from their Establishment in Peter-street, + Westminster, along the line from Pall Mall to Temple-bar, compleatly + surrounding the parish of St. Martin's in the Field. Main pipes are + also placed in the Hay-market, Coventry-street, Long-Acre, St. + Martin's-lane; and in the principal parts of the parishes of St. James + and St. Ann. + + In the East end of the metropolis, the gas-light _mains_ extend from + Cornhill to St. Paul's, Wood-street, Fore-street, &c.--Consent has + also been given to the incorporated Gas-Light Company for laying their + pipes in the parish of St. Stephen's in the Field; St. Paul + Covent-garden; St. Mary-le-Strand; St. Clement Danes; St. George's, + Bloomsbury; St. Giles's in the Fields; St. Andrew's, Holborn, above + the bars; part of the parish of St. Mary-la-bonne; besides several + other districts, comprehending the whole of the city and suburbs of + Westminster. + +Enough therefore, has been done to prove the possibility of lighting +houses, and streets, with gas, which would have been regarded twenty +years ago as an extravagant paradox.[24] + + [24] I am informed by Mr. CLEGG, the engineer of the Chartered + Gas-Light Company, under whose direction the new system of lighting is + carried on, that the total length of pipe laid down, as mains, in the + streets of London amounts already to nearly 15 miles. + + In the Eastern part of London, the same Company is engaged to lay + their pipes in the principal parts of Whitechapel, Spitalfields, St. + Luke's, and the adjoining neighbourhood. + + One part of the city of London, extending from Temple-bar to the West + end of Cheapside; from Newgate-street to Holborn Bars, together with + the intervening streets, is also provided with pipes laid down by + another gas-light association, who have opened a new Establishment in + Water-lane, Fleet-street, but are unconnected with the Chartered + Company. A third company is projected in Southwark, and a fourth in + the Eastern district of London, creating by a rivalry of interest, + that laudable competition which always proves beneficial to the public + at large, and which cannot fail to accelerate the progress of this new + art of procuring light. + +The Church of St. John the Evangelist in this metropolis has been +illuminated with gas-lights for upwards of two years: the lights +employed in this edifice is equal to 360 tallow candles eight to the +pound. The avenues to the House of Lords and House of Commons, +Westminster-hall, Westminster-bridge; the house and offices of the +Speaker of the House of Commons, the Mansion-house, and many other +places, deserve to be named, as having already adopted this species of +illumination. + +Another advantageous application of the gas-light must be the supplying +of light-houses. + +From the splendour and distinguishing forms which the gas-light flame is +capable of assuming, no light is better calculated for signal-lights +than this. By means of one single furnace as much gas might readily be +procured as would furnish a flame of sufficient intensity, during the +longest winter night, exceeding in brilliancy or intensity of light any +light-house in Britain or elsewhere. + +If every light-house round this island were possessed of a gas-light +furnace, one-half part of the enormous expence which they at present +require would furnish a much more brilliant light. The cheapness of this +light and its efficacy for the purpose, would soon multiply the number +of light-houses, and thus most essentially contribute to the security of +navigation on our coast. The gas may be made to issue from tubes by long +narrow slips, and a surface of flame produced of any given dimensions, +and free from all smoke that would obscure the reflectors. + +The ease with which the largest gas-light flame is instantly +extinguished by shutting the stop-cock, and the readiness with which a +long line of gas catches fire by applying a lighted taper to one +extremity, are properties that cannot fail to recommend it for the +purposes of telegraphic communications by night. Another application of +the gas unquestionably might be the lighting of barracks, arsenals, +dock-yards, and other establishments where much light is wanted in a +small place. + +The annual expence of lighting the barracks of Great Britain is said to +fall little short of 50,000l. a small part of which on the new plan, +would supply them with a much purer and safer light. + +The uses of the gas-lights already enumerated must of themselves, +justify us in attaching great importance to the discovery, and if +reduced to practice all over the kingdom, would employ a large capital +in a way the most advantageous and productive. But the utility of this +light will be almost indefinitely increased to the use of private +families. That such an application is practicable, in all towns of Great +Britain, is obvious, from what has been done already, and that it would +be highly economical and ornamental, there can be little doubt. + +By means of gas we may have a pure and agreeable light at command in +every room of our house, just as we have the command of water, with this +singular advantage, that these lights may burn for hours within an inch +of the most combustible substance without danger, because they neither +can burn down like a candle nor emit sparks. These properties make the +gas-lights a most desirable light on board our ships of war, where +severe regulations are necessary to prevent danger from fire, which +after all are frequently evaded. The gas-light might be used in the +store-rooms, and even in the powder magazine, and the captain would +completely command the supply of light by the possession of the key +which opens and shuts the stop-cock. A small apparatus which may be +erected at a trifling expence would be sufficient for that purpose. + +In shops, counting-houses, and public offices, the advantages are a +white light, nearly equal to day-light, a warmth which almost supersedes +the use of fires, a total absence of smoke, smell, and vapour, and great +economy of labour. + +The heat produced by gas-lights must be observed by every one who has +had an opportunity of attending to it in the most superficial manner, +and the reason why gas-lights produce more heat than oil or candle-light +will not appear strange to our chemical readers (and who is there now +that does not know something of chemistry?) when it is considered that +the gas-light flame condenses more air than the flame of oil and tallow, +and consequently must produce more heat. + +The flame of gas may be produced in so large a surface, as to be applied +to heat the most spacious apartments as well as to light them. + +If the gas is made to issue by a circular rim of about twelve inches +diameter; it forms a sort of an Argand lamp on a great scale, and it is +manifest that a circumference of three feet of flame will heat the air +very rapidly, and with such uniformity that we need no longer be exposed +to the partial heating occasioned by the strong draft of a large fire. A +lamp of this description in the centre of a large room, with a very +small fire to secure a gradual renewal of the air would enable us to +enjoy the most healthful and agreeable temperature. + +From trials made on this subject, I am enabled to state, that three +Argand's lamps, consuming five cubic feet of gas per hour, are +sufficient to keep a room 10 feet square at a temperature of 55° Fahr. +when the air without doors has a temperature of freezing.[25] + + [25] Mr. DALTON's method of ascertaining the comparative quantity or + effects of heat evolved during the combustion of different inflammable + gases, and other substances capable of burning with flame, as stated + in his System of Chemistry, vol. I. p. 76, deserves to be recommended + to those who are more immediately interested in this subject. The + process, which is simple, easy, and accurate, is as follows: + + Take a bladder of any size, (let us suppose for the sake of + illustration, the bladder to hold or to be equal in capacity to 30,000 + grains of water,) and having furnished it with a stop-cock and a small + jet pipe, fill it with the combustible gas the heating power of which + is to be tried. Take also a tinned iron vessel with a concave bottom + of the same capacity, pour into it as much water as will make the + vessel and water together equal to the above stated bulk of water in + the bladder, viz. 30,000 grains. This being done, set fire to the gas + at the orifice of the pipe, and bring the point of the flame under the + bottom of the tinned vessel, and suffer it to burn there, by squeezing + the bladder till the whole of the gas is consumed. The increase of + temperature of the water in the tinned vessel being carefully noticed + before and after the experiment, gives very accurately the heating + power of the given bulk of the inflammable gas. + + It was thus proved that-- + + Olefiant gas raises an equal volume of water 14° + Carburetted hidrogen, or coal gas 10 + Carbonic oxid 4 + Hidrogen 5 + Spermaceti oil 10 grains burnt in a lamp raised + 30,000 grains of water 5 + Tallow 5 + Wax 5,75 + Oil of turpentine 3 + Spirit of wine 2 + +In all processes of the arts where a moderate heat is wanted the +gas-light flame will be found very advantageous--even on a large scale +this flame may be used with profit. It possesses advantages which cannot +be obtained from flaming fuel, where much nicety is required; because no +fuel can be managed like the flame of coal-gas. For it is well known, +that when too little air be given to flaming fuel it produces no flame, +but sooty vapour; and if too much air be admitted to make those vapours +break out into flame, the heat is often too violent. It is a fact, that +flame, when produced in great quantity, and made to burn violently, by +mixing with a proper portion of fresh air, driving it on the subject, +and throwing it into whirls and eddies, thereby mixing the air with +every part of the hot vapour, produces a very intense heat. + +The great power of a gas-flame does not appear when we try small +quantities of it, and allow it to burn quietly, because the air is +not intimately brought into contact with it, but acts only on the +outside; and the quantity of burning matter in the surface of a small +flame is too minute to produce much effect. + +[Illustration] + +But when the flame is produced in large quantity and is freely brought +forward into contact and agitated with air, its power to heat bodies is +immensely increased. It is therefore peculiarly proper for heating large +quantities of matter to a violent degree, especially if the contact of +solid fuel with such matter is inconvenient. + +As the gas-flame may be made to assume any shape and intensity, and as +there is nothing to spill, it may be exhibited under such variety of +forms and designs, as cannot fail to give rise to the most tasteful +ornamental illumination. + +PLATES III. IV. and V. exhibit such designs of different kinds of +gas-lamps, chandeliers, lustres, candelabras, &c. as are already in use +in this Metropolis. + +PLATE III. fig. 1, represents a _Rod Lamp_. The gas passes through the +rod _a_, to the Argand burner, which is surrounded by a cylindrical +chimney, _c_, swelling out at the lower extremity. The construction of +the Argand burner we have mentioned already, _p._ 78. + +In all the gas-light burners, constructed on Argand's plan, care should +be taken that the flame be in contact with the air on all sides, and +that the current of air be directed towards the upper extremity of the +flame. This may be effected by causing a current of air to rise up +perpendicular from the bottom of the chimney glass, and to pass out +again through the contracted part, or upper extremity of the chimney; +but no other current of air should ever be permitted to come near the +gas-flame, or enter the glass chimney which covers or defends the light; +for if more air be permitted to mix with the flame than is sufficient +for the compleat combustion of the coal-gas, it necessarily diminishes +the heat, and consequently reduces the quantity of light. + +Fig. 2. _A Rod Gas Lamp, with branches._ The gas passes through the +hollow rod, _a_, and part of the hollow branch, _b_, to the burner of +the lamp. The cylindrical shaped glass, _c_, exhibited in this figure, +is not so well adapted for the compleat combustion of coal-gas, as the +belly-shaped chimney, _c_, represented in fig. 1, 3, 5, 6, because the +ascending current of fresh air is not turned out of its perpendicular +course, and thrown immediately in a concentrated state, into the upper +part of the flame where the combustion of the gas is less perfect. The +exterior current of air which enters at the bottom into the lamp, rises +merely with a velocity proportioned to the length of the cylinder, and +to the rarefaction of the air in the same, but without being propelled +to the apex of the flame, as it should do, and is made to do, in the +bellied glass adapted to the lamp, fig. 1. + +Fig. 3. _A Bracket Lamp._ _a_, the tube which conveys the gas to the +burner; _b_, the stop-cock of the tube. + +Fig. 4. _A Pendent Rod Lamp_; in which the gas is supposed to come from +a pipe above, through the ceiling, into the pipe, _a_, to supply the +burners. The tulip-shaped chimney, _b_, of this lamp, is likewise ill +adapted for gas-light burners. + +Fig. 5. _A pendent double-bracket Lamp._ The gas passing through the +perpendicular tube, _a_, into the brackets, _b_ _b_; _c_ shows the +Argand burner. + +Fig. 6. _A swing Bracket Lamp._ _a_, the gas-pipe with its stop-cock; +_b_, a brass ball, communicating with the pipe, _a_; _c_, the conducting +tube, ground air-tight into the ball, _b_, and communicating with the +burner of the lamp, so as to allow it to have an horizontal motion. + +Fig. 7. Shews the construction of the ball _b_, and pipe, _c_, of the +lamp, fig. 6. + +Fig. 8. _A Swing Cockspur Lamp_, constructed upon the same plan as fig. +6. These two lamps are very convenient for desks in counting-houses, &c. + +Fig. 9. A stop-cock with ball and socket, which, when adapted to a +gas-light pipe, allows it to have an universal motion, so that the light +may be turned in any direction. + +Fig. 10. Section of the stop-cock, with ball and socket. + +Fig. 11. Shows the ball and socket, fig. 9, in perspective. + +[Illustration] + +PLATE IV,[26] fig. 1. _A Candelabrum_; the gas pipe ascending from +the floor of the apartment, through the column _a_, and terminating in +the burner of the lamp. + + [26] The gas-lamps exhibited in this plate, are employed in the + library, counting-house, warehouse, and offices of Mr. ACKERMAN, and, + by whose permission, they are copied on this occasion. + +Fig. 2. _A fancy pendent Cockspur Lamp._ The gas being transmitted to +the burners, _c_ _c_, by means of the pipe, _a_. + +Fig. 3. _A Pedestal Argand Lamp._ _a_, the pipe and stop-cock, which +transmits to, and shuts off the gas from the burner of the lamp. + +Fig. 4. _A Pedestal Cockspur Lamp._ _a_, the stop-cock and gas-pipe. + +Fig. 5. _A fancy bracket Cockspur Lamp_, intended merely to show that +the coal-gas, as it passes to the burner, is perfectly devoid of colour, +and invisible. _a_ is a glass vessel furnished at its orifice with a +brass cap, _c_, and perforated ball, out of which the gas-flame +proceeds. _b_, the pipe which conveys the gas into the glass vessel, +_a_. + +Fig. 6. _A Bracket Argand Lamp._ _a_ and _b_, the gas pipe communicating +with the burner. + +Fig. 7 and 8. _A Horizontal Bracket Lamp._ _a_, the gas pipe, supposed +to be concealed in the ceiling. _b_, the communicating pipe, which, +together with _c_, branches out at right angles at _d_ _d_. _e_ _e_, are +the burners of the lamp. + +PLATE V. fig. 1. _A Candelabrum_, into which the gas-pipe ascends from +the floor of the apartment, the lateral branches communicating with the +central tube. + +Fig. 2. _An Arabesque Chandelier._ The gas enters from the ceiling of +the room into the rope-shaped pipe, _a_, from which it proceeds through +one of the arched ribs, _b_ _b_, into the horizontal hoop, or pipe, _c_. + +Fig. 3. _A Roman Chandelier._ The gas enters through the inflexible +hollow chain, _a_, into the central tube, _b_, from whence the burners +are supplied by the lateral branches, _c_ _c_. + +Fig. 4. _A Gothic Chandelier._ The gas is transmitted to the burners +through the rope, _a_, which includes a tube, and the communication with +the burners is established through the lateral branches. + +Fig. 5. _A Pedestal Figure Lamp._ The gas is here made to pass by means +of a pipe through the body of the figure into the lattice-work +_plateau_, constructed of hollow and perforated brass tubes. + +[Illustration] + +Fig. 6. _A Pedestal Vase Lamp._ The gas-tube enters through one of the +claw-feet of the altar-shaped pedestal, into the glass vase, _a_, at +the bottom of which it joins the tubes communicating with the metallic +corn-ears, _b_, at the upper extremities of which it forms _jets de +feu_. + +Fig. 7. _A Girandole._ The gas enters through the bracket, _a_, and is +conveyed to the burners by the descending tubes, _b_ _b_. + +Fig. 8. _A Candelabrum_, having a central pipe, through which the gas is +conducted to the burner at the top. + + +OTHER PRODUCTS OBTAINABLE FROM COAL: NAMELY, COKE, TAR, ESSENTIAL OIL, +&c. + +Having thus far considered the nature of coal-gas as a substitute for +the lights now in use, it will be necessary to attend more particularly +to some other products which are obtained during the production of this +species of light: namely, coke, tar, ammoniacal liquor, &c. + +_Coke._--The substance called coke, which constitutes the skeleton of +the coal, or its carbonaceous base, is left behind in the retort, after +all the evaporable products have been expelled from the coal by +heat.--See page 85. + +It is sufficiently known, that coke is a more valuable fuel than the +coal from which it is obtained. + +Hence, immense quantities are prepared in the large way, but the gazeous +and other substances are lost in the process employed for carbonizing +the coal.[27] In the manufacture of coal-gas, the coke comes from the +retort, enlarged in size, and greatly diminished in weight, when +compared with the original coal. In whatever state the coal may be when +introduced into the retort, the coke is uniformly taken out in large +masses, so that the refuse coal, or dust, and sweepings of the pit, +which are now thrown away, may be employed and converted into an +excellent fuel. Coke is decidedly superior to coal for all domestic, and +more especially for culinary purposes; the heat which it throws out +being more uniform, more intense, and more durable. No flame, indeed, +accompanies it, and it seldom needs the application of the poker,--that +specific for the _ennui_ of Englishmen; but these deficiences are more +than balanced by the valuable property of emitting no sparks, of giving +more heat, and burning free from dust and smoke. + + [27] The preparation of coke is as follows:--A quantity of large coal + is placed on the ground in a round heap, of from 12 to 15 feet in + diameter, and about two feet in height; as many as possible of the + large pieces are placed on their ends, to form passages for the air; + above them are thrown the smaller pieces and coal dust, and in the + midst of this circular heap, is left, a vacancy of a foot wide where a + few faggots are deposited to kindle it. Four or five apertures of this + kind are formed round the ring, particularly on the side exposed to + the wind; there is, however, seldom occasion to light it with wood, + for other masses being generally on fire, the workmen most frequently + use a few shovels of coal already burning, which acts more rapidly + than wood, and soon kindles the surrounding pile; as the fire spreads, + the mass increases in bulk, puffs up, becomes spongy and light, cakes + into one body, and at length loses its volatile parts, and emits no + more smoke. It then acquires an uniform red colour, inclining a little + to white, in which state it begins to break into gaps and chinks, and + assumes the appearance of the under part of a mushroom; at this moment + the heap must be quickly covered with ashes, of which there is always + a sufficient provision around the numerous fires, where the coke is + prepared. + +That coke must give out more heat during its combustion than coal, will +at once become obvious, when we consider that the quantity of matter +which, in the combustion of coal is changed from a solid to a state of +elastic fluidity, must necessarily carry off a portion of caloric, +which then becomes converted in a latent state without producing heat, +whilst the glow of the coke radiates caloric with an intensity +unimpaired by any demand of this kind. + +It is thus that coke, though somewhat more difficult of ignition than +common coal, always gives out a more steady, a more lasting, and a more +intense heat. + +The only inconveniences that attend the use of coke is, that, as it +consumes, it leaves much more ashes than common coal, charcoal, or wood; +and these much heavier too, which are, therefore, liable to collect in +such quantity as to obstruct the free passage of air through the fire; +and further, that when the heat is _very intense_, these ashes are +disposed to melt or vitrify into a tenacious drossy substance, which +clogs the grate, the sides of the furnace and the vessels. This last +inconvenience is only troublesome, however, when the heat required is +very great. In ordinary heats, such as are produced by kitchen or +parlour grates, the ashes do not melt, and though they are more copious +and heavy than those of charcoal or wood, they do not choke up the +fire, unless the bars of the grate be too close together. + +The relative effects of heat produced by coke and coal are as follows:-- + +Six hundred pounds of pit-coal are capable of evaporating 10 cubic feet +of water in 20 hours, and 430lb. of coke are capable of evaporating 17 +cubic feet of water in 12 hours and a half.[28] + + [28] In order to learn the relative effect of different kinds of fuel, + with regard to their capability of producing heat, chemistry teaches + that equal quantities of fuel alike expended, will raise the + temperature of a given quantity of water through the same number of + degrees; whence, by knowing the original quantity and temperature of + water, together with the quantity of fuel expended to raise the water + to the boiling point, the result sought may be expressed by stating + the quantity of water at 30 degrees, which would have been raised 180 + degrees by one pound of the fuel employed; or in the form of a rule, + + Multiply the quantity of water by the number expressing the degrees + actually raised; multiply the number of pounds of fuel expended by 180 + degrees. Divide the first product by the latter, and the quotient will + express the water which would have been raised 180 degrees by one + pound of the fuel. Or equal quantities of water may be compleatly + evaporated under equal surfaces and circumstances, with the different + kinds of fuel, the nature of which is to be examined; the quantities + of fuel expended for that purpose give the relative effect of the + different kinds of fuel, with regard to their power of producing + heat. + +The Earl of Dundonald has shown that, in the application for burning +lime, a quantity of coke uniformly burns a given portion of lime-stone +in one-third part of the time that the quantity of coal from which the +coke had been made could do. + +This effect is to be accounted for from having previously freed the +coal, or rather its coke, from the moisture and the tar, which it sends +out during combustion, and which condenses on the middle and upper +strata of stratified limestone and coal in the lime kiln, and impedes +the whole mass of materials from coming into a rapid and compleat +ignition; because the greater the quantity of materials, and the sooner +the whole is ignited, the better and more economically the lime is +burned, both as to coals and time; the saving of which last is a +material object, especially at lime-kilns where there is in the summer +time a great demand for lime, the coke occasioning the kilns to hold a +_third more lime_ at the _same time_. + +In the art of making bricks, in the smelting of metallic ores, and the +drying of malt, the advantages of coke over coal, are sufficiently +known. + +The following account given by Mr. Davis,[29] shows that the advantages +that may be derived in the processes of burning lime, plaster of paris, +and bricks, by means of coke, are greater than at first sight might be +imagined. + + [29] Philosophical Magazine, Vol. 33, p. 435. + +"The coke obtained in the gas process is so valuable, that it appears +inexplicable that men should not avail themselves of this mode of +procuring light, to the almost total exclusion of all other methods now +in use. As a landholder, placed among an industrious but wholly +illiterate society of men, I have had the more opportunity of trying +this species of fuel or coke, which I could not otherwise procure in +this sequestered spot, at a tolerably cheap rate, for purposes to which +it has not, as far as I know, been hitherto employed. I must tell you +that I am my own lime-burner, plaster of paris baker, and brick-maker; +and that in these processes of rural economy I have derived the greatest +benefits from this species of fuel, which I now prepare at a cheap rate, +although I waste almost the whole of the light of the coal gas +intentionally. The coal which I employed formerly for the burning of +limestone into lime, is a very inferior kind of small coal, called here +Welsh culm. The kiln for burning the limestone into lime is a cup-shaped +concavity, surrounded with solid brick-work, open at the top, and +terminating below by an iron grate. It has a stone door that may be +opened and closed for charging and emptying the furnace when required. +This furnace I formerly charged with alternate strata or layers of small +coal and limestone, the latter being broken previously into pieces not +larger than a man's fist, until the kiln was completely filled. The +stone is thus slowly decomposed; the upper part of the charge descends, +and when it has arrived at the bottom of the furnace new strata are +super-imposed, so as to keep the furnace continually full during a +period of 50 hours. The quantity of lime I procured with small coal +formerly amounted to 85 bushels. The strata of coal necessary for the +production of this quantity of lime require to be four inches thick, and +the time necessary for calcination was, as stated already, 50 hours. + +"On applying coke instead of coal, the produce of lime may be increased +to nearly 30 per cent. from the same furnace, and the time required to +effect the calcination of this quantity of lime-stone is reduced to 39 +hours: it also requires _less attendance_ and _less labour_, and the +whole saving, thus accomplished, amounts to more than 50 _per cent. on +the lime-kiln_. + +"I have lately also employed coke for the burning of bricks. My bricks +are burnt in clamps, made of bricks themselves. The place for the fuel, +or fire-place, is perpendicular, about three feet high. The flues are +formed by gathering or arching the bricks over, so as to leave a space +between each of a brick's breadth; and as the whole of the coal, if this +fuel be employed, must, on account of the construction of the pile, be +put in at once, the charge of the bricks is not, and never can be, burnt +properly throughout; and the interference of the legislature, with +regard to the measurement of the clamp, is a sufficient inducement for +the manufacturer to allow no more space for coal than he can possibly +spare. + +"If coke be applied instead of coal, the arches, or empty spaces in the +clamp or pile, as well as the strata of the fuel, may be considerably +smaller: the heat produced in this case is more uniform and more +intense, and a saving of 30 per cent. at least is gained. + +"In the baking my own plaster-stone I also employ coke. The calcination +of the stone for manure I perform in a common reverberatory furnace, and +the men who conduct the process (who are otherwise averse to every thing +new) are much pleased with the steadiness of the fire, and little +attendance which the process requires, when coke is used instead of +coal. + +"These are the few facts I wish to state, with regard to the useful +application of this species of fuel, which, no doubt, hereafter will +become an object of economy of incalculable advantage to individuals, if +its nature be better understood than it is at present." + +The quantity of coke obtainable from a given quantity of coal varies +according to the nature of the coal employed. One chaldron of Newcastle +coal produced, upon an average, in the gas-light manufacture, from one +chaldron and a quarter to one chaldron and a half of well formed coke. +If the carbonization of the coal has been carried to its utmost point, +the coke produced, has a brilliant silvery lustre. Such coke is +excellent for metallurgical operations, because it stands the powerful +blast of the bellows, but for culinary and other purposes of domestic +economy, the carbonization should not be carried so far, because, the +coke then produced, kindles more readily and makes a more cheerful fire. + +_Coal-tar_, _Oil_, and _Pitch_.--Another, valuable product obtainable +from pit-coal, is coal-tar.[30] This substance is deposited, in the +purification of the coal-gas, in a separate vessel destined to receive +it. + + [30] In the year 1665, Becher, a German chemist, brought to England + his discovery for extracting tar from coal, this distillation he + performed in close vessels. It is not mentioned in the records of the + time, whether Becher obtained, or rather collected, any other articles + than the tar. + +The coal-tar is so called from its resembling common tar in its +appearance, and most of its qualities. + +Several works have been, at different times, erected both in England and +on the continent, to procure from coal a substitute for tar; but they +turned out unprofitable speculations. In 1781, the Earl of Dundonald +invented a mode of distilling coal in the large way, which enabled him +not only to form coke, but, at the same time, to save and collect the +tar. Even this process however, for which a patent was taken out, has +gained very little ground. Its object was still too limited; for though +some of the ingredients of coal were procured, they were procured at an +expense that nearly balanced the profits; and no attention whatever was +paid to the coal gas, which constitutes the most important part of coal. + +Coal-tar may be used with advantage for painting and securing wood that +is exposed to the action of air or water. The wood being warmed, the tar +is applied cold, and penetrating into the pores, gives the timber an +uncommon degree of hardness and durability. + +One chaldron of Newcastle coal produces in the gas-light manufacture +from 150 to 180lb of tar, according to the circumstances under which it +is produced. See page 94. + +The tar obtained from Newcastle coal-tar is specifically heavier than +that produced from cannel-coal; hence it sinks in water, whereas the +latter swims on the surface of that fluid. + +To render the tar fit for use, it requires to be evaporated to give it a +sufficient consistence. If this process be performed in close vessels, +a portion of an essential oil is obtained, which is known to colourmen +by the name of oil of tar. To obtain this oil, a common still is filled +with the coal-tar, and, being properly luted, the fire is kindled and +kept up very moderate, for the tar is very apt to boil up in the early +part of the process. The first product that distils over is principally +a brown ammoniacal fluid, mixed however with a good deal of oil. As the +process advances, and the heat is increased, the quantity of ammoniacal +liquor lessens, and that of oil increases, and towards the end of the +distillation the product is chiefly oil. + +The oil and ammoniacal water which distil over do not mix, so that they +may be easily separated by decantation. The oil is a yellowish inferior +kind of oil of turpentine, which is very useful in painting ships, for +making varnishes, and other coarse out-door work. + +Two hundred pounds of tar produce, upon an average, fifty-three pounds +of essential oil. + +If the coal-tar is wanted to be converted into pitch, without obtaining +the oil which it is capable of furnishing, the evaporation of it may be +performed in a common boiler; but as it is extremely liable to boil +over, the greatest precaution is necessary in conducting the +evaporation. A boiler constructed on the following plan is very +convenient for the conversion of coal-tar into pitch. The contrivance +consists in adding a spout, or rim, to the common boiler, into which the +tar spreads itself as it rises, and by this means becomes cooled, and +the boiling over is checked. + +[Illustration: _Kettle for boiling Tar._] + +1000lb. of coal-tar produce, upon an average, from 460 to 480lb. of +pitch. A subsequent fusion, with a gentle heat, converts the coal-pitch +into a substance possessing all the characters of _asphaltum_. + +_Ammoniacal Fluid._--The properties of the ammoniacal liquor, which +accompanies the tar, and which is deposited in the tar-cistern, has not +yet been fully investigated. It is employed already in the manufacture +of muriate of ammonia (sal ammoniac). One chaldron of coal affords from +220 to 240lb. of this ammoniacal fluid, which is composed chiefly of +sulphate, and carbonate of ammonia.--Such are the products obtainable +from coal. + +However certain the practicability of extending the new lights to the +dwelling houses of every town and village is, it cannot be expected that +such an event should take place speedily and generally. To eradicate +prejudice, and to alter established habits, is a work which nothing but +time can effect; because prejudice is the effect of habit, and can +seldom be eradicated from the minds of such individuals as consider the +ready occurrence of a proposition as a test of its truth. To establish a +new philosophical theory has, in every instance, required time +sufficient to educate an entire generation of men. The rejection of the +Aristotelian philosophy--the adoption of experimental research--the +substitution of the doctrine of gravitation instead of that of vortices, +and the rejection of phlogiston by modern chemists, are sufficiently +illustrative of this assertion. New arts, and new practices, are still +more difficult to be introduced. The new art of bleaching need merely be +mentioned to prove this assertion. The new grammar--the new rudiments of +science--the new stile--or the new instrument, however superior to the +old in simplicity, facility, and truth, must be less valuable to the +ordinary teacher or artisan, whose memory is familiarized with the +precepts of the latter, and whose only ambition is to earn his +subsistence with the least possible exertion. + +The slowness with which improvements of every kind, make their way into +common use, and especially such discoveries as are most calculated to be +of an extended or general utility is very remarkable, and forms a +striking contrast to the extreme avidity with which those unmeaning +changes are adopted, which folly and caprice are continually sending +forth into the world under the auspices of _fashion_. + +On the first view of the subject it appears very extraordinary, that any +person should neglect, or refuse to avail himself of a proposed +invention, or improvement, which is evidently calculated to economise +his labour, and to encrease his comforts; but when we reflect on the +power of habit, and consider how difficult it is for a person even to +perceive the disadvantages or imperfections of former modes to which he +has been accustomed from his early youth, our surprize will be +diminished, or vanish altogether. + +Many other circumstances, besides prejudice, are unfavourable to the +introduction of new and useful discoveries. Among these jealousy, +malice, envy, and revenge, have too often their share in obstructing the +progress of real improvement, and in preventing the adoption of plans +evidently calculated to promote the public good. + +A plan like the present, which proposes not only to trench upon domestic +habits, but to give an entire new direction to a portion of the skill +and capital of the country, must necessarily encounter the most +strenuous opposition. It is thus that some individuals have mustered all +their strength against the introduction of this new art. An endeavour +has been made to move the public opinion by dismal forebodings of the +Greenland trade, and the subsequent loss of a nursery of British seamen. +This objection is nothing more than the common clamour that is always +set up against every new means of abridging labour, to which had the +public listened, an interdict would have been laid upon the spinning and +threshing machines, the steam engine, and a thousand other improvements +in machinery. + +Indeed such clamour scarcely ever fails to be made when the extension of +machinery and the abridgement of labour or the application of inanimate +powers are considered. On such occasions, it is stated by certain humane +but mistaken objectors, that the scheme of mechanical and chemical +improvement is pointed against the human species--that it tends to drive +them out of the system of beneficial employment--that the introduction +of machinery is injurious to the labouring class of society, by +abridging their work. Two creatures offer themselves for employment and +support--a man and a horse. I must invariably prefer the latter, and +leave the former to starve. Two other beings--a horse and a +steam-engine, are candidates for my favour. My preference to the latter +tends to exterminate the species of the former. In both cases it is +stated, that the number of intelligent creatures capable of the +enjoyment of happiness must be diminished for want of support; and that, +on the whole, the sum of the proposed improvement is not only a less +proportion of good to society, but a positive accession of misery to the +unemployed poor. + +On this wide and extended argument, which can in fact be maintained +against all improvements whatever in no other way than by insisting that +the savage state of man, with all its wants, its ignorance, its +ferocity, and its privations, is preferable to the social intercourse of +effort and division of labour we are habituated to prefer, it may be +sufficient to observe that it includes matter not only for reasoning and +induction, but also for experiment. By reference to the matter of fact, +though it must be allowed that new improvements, which change the habits +of the poor, must at first expose them to a temporary inconvenience and +distress, against which, in fairness, it is the duty of society to +defend them; yet the invariable result of such improvements is always to +better the condition of mankind. A temporary inconvenience to +individuals must often be incurred for the sake of general national +benefit. + +It is to manufactories carried on by machinery and to the abridgment of +labour, that this country is indebted for her riches, her independence +and pre-eminent station among the nations of the world. + +But let us return to the subject.--The progress of the new mode of +lighting with coal-gas can never wholly supersede the use of candles and +moveable lights. The objection with regard to the Greenland trade is +equally futile. This traffic, might with more propriety be called a +drain, than a nursery, of the naval force. The nature of the Greenland +service requires that the crew should consist chiefly of able-bodied +sailors; and being protected men, not subject to the impress law, they +are thus rendered useless for national defence. The nursery of British +seamen is the coasting trade; and if the gas-light illumination be put +in practice to a large extent, it will increase that trade as much as it +will diminish the Greenland fishery. + +Even on the extreme supposition that it would annihilate the Greenland +fisheries altogether, we should have no reason to regret the event. The +soundest principles of political economy must condemn the practice of +fitting out vessels to navigate the polar seas for oil, if we can +extract a superior material for procuring light at a cheaper rate from +the produce of our own soil. + +Indeed the fisheries will find ample encouragement, and the consequence +of lighting our streets with gas can prove injurious only to our +continental friends, one of whose staple commodities, tallow, we shall +then have less occasion to purchase. + +There will be less waste indeed, but a greater consumption of coal. The +lower classes of the community are at present very scantily supplied +with firing; and nothing but a reduction of price is necessary to +increase to a very large amount the whole average quantity of fuel +consumed in the country. The lightness of the coke produced in the +gas-light manufacture diminishing the expence of land carriage, will +facilitate its general diffusion--the comforts of the poor will be +materially augmented, and a number of useful operations in agriculture +and the arts be carried on, which are now checked and impeded by the +price of fuel. + +If any additional want were wanted for the coke it will readily be +found in the continental market; coke being much better suited than coal +to the habits of most European nations. + +The gas-light illumination cannot tend to diminish the coal-trade; on +the contrary it will prove beneficial to it; it will contribute to lower +the price of the superior kinds of coal, and keep a level which cannot +be shaken under any circumstances; it will contribute to prevent +combinations which do certainly operate to the prejudice of the public, +and do sometimes put this great town at the mercy of particular +proprietors in the north, who deal out coal in the way they please. The +competition thus produced, it is impossible not to consider as an +advantage, which would prevent in future such combinations, and put +those in London out of the reach of them. + +It is worthy observation, that the annual importation of coal into this +Metropolis, is above one million and eighty-eight thousand +chaldrons.[31] + + [31] To give an idea how long there is a probability of Great Britain + being applied with coal from the rivers Tyne and Wear only, it must be + observed, + + _1st_. That the Seams of coal which are now worked at Newcastle and + Sunderland, are equal to a seam or bed of 15 miles by 20 miles. + + _2dly_. That this seam, on an average, is at least four feet and a + half thick. + + _3dly_, That 1-6th part of the above extent is sufficient for pillars + to support the roofs of the mines, &c. + + And, _4thly_, It appears, by experiments, that a cubic yard of coal + weighs 1 ton, or 20 cwt. + + London Chaldrons + + The total consumption of coal from the rivers Tyne + and Wear known from the register to be 2,300,000 + + The number of tons in the above quantity taking the + London chaldron at 27 cwt. is 3,100,000 + + Now a ton weight of coal is estimated to occupy in + the earth the space of one cubic yard. + + The number of cubic yards in the square mile is 3,097,600 + + The beds or seams of coal are, on an average, 4 + feet and a half in thickness, which increases the + above number of cubic yards in the square mile by + half the number of square yards to 1,548,800 + + And hence the square mile of the beds or seams of + coal we are describing contains, of cubic yards + and tons of coal 4,645,000 + + A deduction of 1-6th for pillars to support the + mine, &c. 800,000 + + The number of tons per square mile 5,445,000 + + We have already mentioned the length and breadth of the seams of coal + to be equal to 20 miles by 15, making an area of 300 square miles, and + consequently a source of consumption for 375 years. + +It may be objected to the universality of our conclusion, that the price +of coals, differing very much in different places, will occasion a +variation in the expence of the new mode of illumination. But there are +two reasons why this should have less place, because we find, in Mr. +Murdoch's statement, page 69, that of 600l. the estimated yearly expence +of lighting the cotton mill, 550l. consist of interest of capital, and +tear and wear of apparatus, leaving the cost of coal only 50l. a sum so +trifling, when we reflect that it replaces 2000l. worth of candles, that +the price of coal, even where it is highest, can but slightly affect the +general profits.[32] + + [32] See, also, Mr. Ackermann's statement, page 71. + +_2dly_, The coal, by yielding the gas and other products,--namely, tar, +pitch, ammoniacal liquor, &c. of which we have treated already, is +converted into a substance, increased in bulk, and in the power of +producing heat, namely, coke; and as a manufactory generally requires +heating as well as lighting, there will be a gain both ways. The +manufacturer, by distilling his coal, instead of burning it as it comes +from the pit, will save his candles and improve his fuel. One effort at +the outset, in erecting a proper apparatus, will reduce his annual +disbursement, for these two articles of prime necessity, much in the +same manner, (though in a far greater degree) as the farmer gains by +building a thrashing machine and laying aside the use of the flail. + +The principal expence in the pursuit of this branch of civil and +domestic economy is therefore the dead capital employed in erecting the +machinery destined for preparing and conveying the gas; the floating or +live capital is comparatively small. At the same time, were we to offer +an advice to the public on this subject, it would be, that no private +individual resident in London should attempt to light his premises for +the sake of economy with coal-gas by means of his own apparatus, whose +annual expence for light does not exceed 60l. because the expence of +erecting and attending a small apparatus is almost as great as one +constructed on a larger scale would be. For if the quantity of gas +wanted is not sufficient to keep the retorts continually in a red-hot or +working state, the cost of the gas will be considerably enhanced; +because either the empty retorts must be continued red-hot, or the fire +must be suffered to go out; and the retorts, when cold, cannot be +brought to a working state, that is to say, be made red hot again, but +at a considerable expence of fuel, which must be wasted to no purpose. +Whereas, if the retorts are constantly kept red hot and in action, one +half of the coal necessary to produce a given quantity of gas will then +be saved. But when a street, or a small neighbourhood is wanted to be +lighted, and the retorts can always be kept in a working state, that is +to say, red hot, the operation may be commenced with safety; because the +sum required for erecting the apparatus, and the labour attending it, +together with the interest of money sunk, will then soon be liquidated +by the light which it will afford. + +Individuals, therefore, may engage in the distillation of coal, and +trade with advantage in the articles produced by that process, and the +lighting of cities may be accomplished without the aid of incorporated +bodies; and parishes may be lighted by almost as many individuals as +there are streets in a parish. + +From experiments, made by Mr. CLEGG, on the effects produced by a number +of gas-lights, of a certain intensity, there is reason to believe that +the streets of small towns might be illuminated at a cheaper rate, by +means of a tower, or pagoda, furnished with gas-lamps, than can be done +in the ordinary way by street lamps: the gas being conducted to the top +of the building from the apparatus below, and the light directed down +again, upon the objects to be illuminated, by means of reflectors placed +at a certain angle. By this contrivance, all the main pipes which convey +the gas through the streets, as well as those collateral ones that +branch out from them to the street lamps, would be saved, and thus +compensate for the expense of the tower. + +The most beneficial application of gas-lights unquestionably is in all +those situations where a great quantity of light is wanted in a small +place: and where light is required to be most diffused, the advantages +of this mode of illumination are the least.--Hence, as already stated, +the lighting of the parish, or street-lamps only, without lighting shops +or houses, can never be accomplished with economy. + +We have noticed before the reason why the price of coals can have little +effect upon the gas-light; because the very refuse, or small coals, +called slack, which pass through the screen at the pit's mouth, and +which cannot be brought into the market--nay, even the sweepings of the +pit, which are thrown away, may be employed for the production of +coal-gas. It makes no difference in what form the coal is used, and this +circumstance may contribute to enable the coal-merchant to furnish coals +in larger masses, and as they come from the mine, instead of increasing +the bulk by breaking them into a smaller size,[33] which is a practice +commonly adhered to. This unquestionably reduces the value of coals; +because the quantity of radiant heat generated in the combustion of a +given quantity of any kind of fuel depends much upon the management of +the fire, or upon the manner in which the fuel is consumed. When the +fire burns bright, much radiant heat will be sent off from it; but when +it is smothered up, very little will be generated: most of the heat +produced will then be expended in giving elasticity to a thick dense +vapour, or smoke, which is seen rising from the fire; and the combustion +being very incomplete, the carburetted hidrogen gas of the coal being +driven up the chimney without being inflamed, the fuel is wasted to +little purpose. + + [33] It is not generally apprehended, how very wasteful the use of + small coals is in the ordinary open fire-grates. Necessity makes us + use the poker very much, particularly, when the coals are small; and + habit prevails even when they are large. By the constant stirring of + the fire almost the whole of the small coal passes through the bars; + and consequently a great deal goes to the dust-hole without being + burnt at all. To prove this, we need only take a shovel full of ashes + and put them into a pail, and then pouring water over them, which + being gently run off, will carry away nearly all the light and burnt + parts: and leave an astonishing quantity of bright unburnt coal, which + has escaped from the fire-place, in consequence of being small. + + When the grate of the fire-place is large, and the small coals are + thrown behind; or when we can have patience enough to bear the cold + for an hour or two, or contrive to have the fire lighted a long time + before we want it, the small coal may be of some use, but the fire + made with it is never strong, nor so bright; and does not burn so long + as a fire made with large or round coals: it often requires the help + of the poker, and produces a great quantity of breeze. + + The loss in the use of small coals is more considerable to the poor, + who cannot keep large fires. When they want their breakfast or dinner, + the time they can spare is limited; and to have their water sooner + boiling, or their meals quicker ready; they must make use of the + poker, and lose a great deal of coal. This fact is so evident, that + any body who wishes to make the experiment before recommended, will + find that much more bright coal goes to the dust-hole of the poor man, + than to the dust-hole of a rich family, where, the fire-place being + large, the small coal has more chance of burning. + + The loss is still greater to the poor, in consequence of the inferior + sorts of coal which are sold to them. If it is the light sort, it + burns too quick, and they consume double the quantity; if the strong + sort, it burns too slow, and is nearly as wasteful; for a great + quantity of it then goes to the dust-hole without having been lighted + at all. + + An incorrect opinion is often entertained, that the real quantity of + coal contained in a sack is lessened by separating or screening the + small from the round coals; but we must recollect, that any compact + body occupies less space than is required to contain the same matter, + reduced to smaller irregular pieces, or to powder.--Now the screening + only takes away the finest dusty part of the coals, and admits more + small pieces of round coals to be filled into the sack. + +Nothing can be more perfectly devoid of common sense, and wasteful and +slovenly at the same time, than the manner in which chimney fires, where +coals are burnt, are commonly managed by servants. They throw on a load +of (perhaps all small) coals at once, through which the flame is hours +in making its way; and frequently it is not without much care and +trouble that the fire is prevented from going quite out. During this +time no heat is communicated to the room; and, what is still worse, the +throat of the chimney being occupied merely by a heavy dense vapour, not +possessed of any heating power, and, consequently, not having much +elasticity, the warm air of the room finds less difficulty in forcing +its way up the chimney and escaping, than when the fire burns bright, +and the coal-gas is ignited. And it happens not unfrequently, especially +in chimnies and fire-places ill-constructed, that this current of warm +air from the room which presses into the chimney, crossing upon the +current of heavy smoke and aqueous vapour which escapes slowly from the +fire, obstructs it in its ascent, and beats it back into the room. Hence +it is that chimnies so often smoke when too large a quantity of fresh +coals is put upon the fire. So many coals should never be put on the +fire at once as to prevent the free passage of the flame between them, +or to prevent them becoming quickly heated, so as to give out the +carburetted hidrogen gas which they are capable of furnishing, and to +cause it to be inflamed, In short, a fire should never be smothered: and +when attention is paid to the quantity of coals put on, there is little +use for the poker; and this circumstance will contribute much to +cleanliness, and the preservation of furniture. + +The author of a paper in the Plain Dealer asserts, that, of the various +perversions of abilities, there is none that makes a human being more +ridiculous, than that of attempting to stir a fire without judgment; to +prevent which he lays down the following rules:--1. Stirring of a fire +is of use, because it makes a hollow where, the air being rarefied by +the adjacent heat, the surrounding air rushes into this hollow, and +gives life and support to the fire, and carries the flame with it. 2. +Never stir a fire when fresh coals are laid on, particularly when they +are very small, because they immediately fall into the hollow place, and +therefore ruin the fire. 3. Always keep the bottom bars clear. 4. Never +begin to stir the fire at the top, unless when the bottom is quite +clear, and the top only wants breaking. + +There is one subject more on which it is necessary to speak.--In the +present instance, the public has been alarmed by representations that +the general adoption of gas-lights would expose us to innumerable +accidents, from the inflammable nature of the gas, and the explosion of +the apparatus in which it is prepared, or the bursting of the pipes by +which it is conveyed. But there is no ground for such fears. + +Those who are familiar with the subject will readily allow, that there +is no more risk in the action of a gas-light machinery, properly +constructed, than there is in the action of a steam-engine, built on +just principles. + +The manufacture of the coal-gas requires nothing more than what the most +ignorant person, with a common degree of care and attention, is +competent to perform. The heating of the gas-furnace, the charging of +the retorts with coal, the closing them up air-tight, the keeping them +red-hot, and discharging them again, are the only operations required in +this art; and these, surely, demand no more skill than a few practical +lessons can teach to the meanest capacity. The workman is not called +upon to exercise his own judgment, because, when the fire is properly +managed, the evolution of the gas goes on spontaneously, and without +further care, till all the gas is extricated from the coal. + +No part of the machinery is liable to be out of order,--there are no +cocks to be turned, no valves to be regulated; nor can the operator +derange the apparatus but by the most violent efforts. And when the +stock of gas is prepared, we may depend on its lighting power as much +as we depend on the light to be obtained from a certain number of +candles or oil-lamps. + +The diversified experiments which have been made by different +individuals, unconnected with each other, have sufficiently established +the perfect safety of the new lights; and numerous manufactories might +be named in which the gas-lights have now been in use for upwards of +seven years, where nothing like an accident has occurred, though the +apparatus in all of them is entrusted to the most ignorant man. + +It would be easy to state the causes which have given rise to some of +those accidents that have spread alarm amongst the public; but of this +it is not my business to speak at length. It is sufficient, on the +present occasion, to state, that those melancholy occurrences which have +happened at some gas-light establishments which I have had an +opportunity of examining, were totally occasioned by egregious failures +committed in the construction of the machinery. Thus, an explosion very +lately took place in a manufactory lighted with coal-gas, in consequence +of a large quantity of gas escaping into a building, where it mingled +with common air, and was set on fire by the approach of a lighted +candle. That such an accident could happen, is an evident proof that the +machinery was erected by a bungler, unacquainted with the most essential +principles of this art; because such an accident might have been +effectually prevented, by adapting a waste pipe to the gasometer and +gasometer house. By this means, if more gas had been prepared than the +gasometer would contain, the superfluous quantity could never have +accumulated, but would have been transported out of the building into +the open air, in as an effectual manner as the waste-pipe of a water +cistern conveys away the superfluous quantity of water, when the cistern +is full. Such an expedient did not form part of the machinery. + +Other instances might be named, where explosions have been occasioned +through egregious mistakes having been committed in the erection of the +gas-light machinery, were this a subject on which I meant to treat. + +That the coal-gas, when mixed with a certain portion of common air, in +close vessels, may be inflamed by the contact of a lighted body, as has +been stated, page 98, is a fact sufficiently known. But the means of +preventing such an occurrence in the common application of gas-lights, +are so simple, easy, and effectual, that it would be ridiculous to dread +danger where there is nothing to be apprehended. In speaking thus of the +safety of the gas-light illumination, I do not mean to deny that no +possible circumstances may occur where the coal-gas may be the cause of +accident. It is certain that the gas, when suffered to accumulate in +large quantities in close and confined places, where there is no current +of air, such as in cellars, vaults, &c. and where it can mix with common +air, and remain undisturbed, that it may be liable to take fire when +approached by a lighted body; but I do not see how it is probable that +such an accumulation of gas should take place in the apartments of +dwelling houses. The constant current of air which passes continually +through the rooms, is sufficient to prevent the possibility of such an +accumulation ever to take place. And with regard to the bursting of the +pipes which convey the gas, no accident can possibly happen from that +quarter; because the gas which passes through the whole range of pipes +sustains a pressure equal to the perpendicular weight of about one inch +of water only, and such a weight of course is insufficient to burst iron +pipes. Nor could the town when illuminated by gas-lights, be thrown +suddenly into darkness, as has been asserted might happen by the +fracture of a main pipe, supposing such an event should take place; +because the lateral branches, which supply the street-lamps and houses, +are supplied by more than one main; and the consequence of a fracture +would be only an extinction of the few lamps in the immediate vicinity +of the broken pipe, because the rest of the pipes, situated beyond the +fracture, would continue to be supplied with gas from the other mains, +as will become obvious from the sketch exhibited in the next page. + +[Illustration: Main pipe, leading from the Gas-light station or +apparatus, situated in Brick Lane, near Old St.[34] + +Main pipe, leading from the gaslight apparatus, or station, at Norton +Falgate.[35] + +Main pipe, leading from the gaslight apparatus, or station, in +Westminster.[36]] + + [34] _The gasometer at this place is equal in capacity to 22000 cubic + feet._ + + [35] _The capacity of the gasometer here is equal to 15928 cubic + feet._ + + [36] _At this station the gasometer is equal in capacity to 14808 + cubic feet._ + +The black lines represent the gas-light mains, or largest pipes, from +which the smaller pipes branch off: they are connected with each other +at the places marked A B C; and the dotted lines represent the smaller +mains, or collateral branches before-mentioned. The main pipes are all +furnished with valves, or cocks, placed at about 100 feet distant from +each other. Now let us suppose that a main pipe, in any part of the +street marked in the sketch, _Pall Mall_, should break, it is evident, +on mere inspection, that the gas which is passing through the main in +the _Strand_, and which is also connected with the main in the +_Haymarket_, _Piccadilly_, and _Coventry Street_, would continue to +supply the broken pipe, and the valve nearest to the fracture being +shut, would prevent the loss of any considerable quantity of gas, and +the few lamps situated between the two valves and the fracture would +therefore only become extinguished. + +Further, let us suppose a main pipe should break in _Piccadilly_; in +that case, the valve being shut on each side of the fracture, the gas +would be supplied from the mains in the _Haymarket_ and _St. James's +Street_. And the same effect would be produced in any part of the town, +supplied with gas-pipes. Besides all this, in the statement thus far +given, we have assumed that all the gas-light mains are supplied with +gas from one manufacturing station only, but which in reality is not the +case. The range of pipes that convey the gas is connected with three +gas-light establishments, situated at different parts of the town; and +the gas which is supplied from these stations is connected with the +whole system of pipes in the streets.[37] If, therefore, one of the +manufactories should be annihilated, it would make no difference, +because the lights would be amply supplied from the other two +manufacturing stations. Hence it is obvious, that the fracture of any of +the gas-light mains, or even the total destruction of one or more of the +manufactories themselves, would be attended with no serious consequence; +and as the system of lighting with gas becomes more extended, the +manufactories, or stations for supplying it, will also be multiplied, to +give effect and security to the whole. + + [37] As shown in the sketch. + +In fact, no danger can arise from the application of gas-lights in any +way, but what is common to candle-light, and lamps of all kinds, and is +the fault of none of them. Even in this case the gas-lights are less +hazardous. There is no risk of those accidents which often happen from +the guttering or burning down of candles, or from carelessly snuffing +them. The gas-light lamps and burners must necessarily be fixed to one +place, and therefore cannot fall, or otherwise become deranged, without +being immediately extinguished. Besides, the gas-light flames emit no +sparks, nor are any embers detached from them. As a proof of the +comparative safety of the gas-lights, it need only be stated, that the +Fire-offices engage themselves to insure cotton-mills, and other public +works, at a less premium, where gas-lights are used, than in the case of +any other lights.[38] The excessive expence of insurance arising from +the numerous candles employed in most of the first rate manufactories, +and the combustible nature of the structure of the buildings; the great +difficulty of retrieving the injury resulting to a well-organised +business, from the accidental destruction of the machinery, are objects +alone sufficient to furnish the strongest economical, as well as +political recommendations, for the adoption of the new lights in all +manufactories where work is done by candle-light. + + [38] Since the preceding pages have been printed, I have seen a + _self-extinguishing gas-lamp_, invented by Mr. CLEGG. This lamp is so + constructed, that the gas cannot flow to the burner, when the flame + becomes extinguished. If, therefore, the lamp should be blown out, and + the stop-cock which supplies the gas be left open, the extinction of + the flame will effectually shut the valve. The action of this lamp + depends upon the expansibility of a metallic rod, heated by the flame + of the lamp, and thus keeping open the valve, whereas, when the lamp + is extinguished, and the rod becomes cold, it contracts to its natural + dimensions, and, by that means, effectually closes the valve. The same + engineer has invented a machine, which both measures and registers, in + the absence of the observer, the quantity of gas delivered by any pipe + communicating with a gas-light main. The machine occupies a space of + about two feet by one foot, and, if put up in a room, house, or other + place, where gas is burnt, will, at any time, by mere inspection, give + an account of the quantity of gas consumed in that place during any + given time. On the present occasion, it would not become me to say + more on these subjects, which, no doubt, Mr. CLEGG will make known to + the public; I shall only remark, that these contrivances do signal + honour to the talents and abilities of the inventor; and that they + will render the greatest services to those who are engaged in the + gas-light illumination. + +After considering the facts so far detailed, many other advantages, +connected with the gas-light illumination, will naturally suggest +themselves to the reader. I have endeavoured merely to point out the +leading characters of the new lights, as they are at present. Ingenious +men may speculate from what has been done to what remains to be +effected, which, no doubt, will embrace objects of the greatest utility +and most extended national importance. The public attention is awakened +to the new properties of coal, and will not rest till they are +extensively applied to economical purposes. The consequence will be, a +considerable defalcation in the revenue. For, in proportion as the +gas-lights are more or less generally adopted in all towns of the +country, the consumption of oil and tallow will be diminished, and the +impost on those articles become less productive; and when this takes +place, Government, no doubt, will share in the profits, by levying a tax +on the new lights. The Exchequer will thus have nothing to fear; as one +branch of the revenue fails, another, and a more productive one, will +supply its place. + +Upon the whole, when we reflect that the object of the gas-light +illumination is to open a source of national wealth, of which nothing +can deprive us, to create, we may almost say, new articles of value, its +friends cannot be thought guilty of great presumption, if they look +forward with confidence to the successful extension of this new art of +civil economy; and if, contrary to all expectations, the effects of +jealousy and prejudice should, in some respect or other, continue here +and there its influence against this new art of procuring light, a firm +perseverance of its application must at length remove that ignorance +which alone can give them birth. + + +TABULAR VIEW, EXHIBITING + + The quantity of GAS, COKE, TAR, PITCH, ESSENTIAL OIL, and AMMONIACAL + LIQUOR, obtainable from a given quantity of COAL; together with an + Estimate of the quantity of Coal necessary to produce a quantity of + Gas, capable of yielding a Light equal in duration of time and + intensity to that produced by Tallow Candles of different kinds. + + -----------+------------------------------------------ + | _Cost of Coal._ + | Minimum. Maximum. Average. + -----------+------------------------------------------ + One Chal. }| + of Coal, }| 40_s_ to 60_s_ -- 50_s_ + from 25 to}| + 28 cwt. }| + One Ton | 30_s_ to 48_s_ -- 38_s_ 6_d_ + One Sack | 3_s_ 4_d_ to 5_s_ -- 4_s_ 2_d_ + One Bushel | 1_s_ 2_d_ to 1_s_ 8_d_ -- 1_s_ 5_d_ + One Peck | 3-1/2 to 5_d_ -- 4-1/4 + One Pound | 1/4 + -----------+------------------------------------------ + + -----------+----------------------------------- + | _Weight of Coal._ + | Min. Max. Aver. + -----------+----------------------------------- + One Chal. }| + of Coal, }| 2,800 to 3,136 -- 2,968 + from 25 to}| + 28 cwt. }| + One Ton | 2,240 + One Sack | 233 to 261 -- 247 + One Bushel | 78 to 87 -- 82-1/2 + One Peck | 19-1/2 to 21-1/4 -- 20-1/4 + One Pound | 1 + -----------+----------------------------------- + + -----------+-------------------------------- + |_Produce of Gas, in cubic feet._ + | Min. Max. Aver. + -----------+-------------------------------- + One Chal. }| + of Coal, }| 8,906 to 11,872 10,388[39] + from 25 to}| + 28 cwt. }| + One Ton | 6,720 to 8,960 -- 7,840 + One Sack | 741 to 988 -- 814 + One Bushel | 247 to 330 -- 290 + One Peck | 61 to 82 -- 71-1/2 + One Pound | 3 to 4 -- 3-1/2 + -----------+-------------------------------- + + -----------+----------------------------------------- + | } |_Candles._ + | } |9,516 11 to the pound. + One Chal. }| }[39]Equal to |8,651 10 do. + of Coal, }| }as many tallow |7,786 9 do. + from 25 to}| }candles, 12 in |6,921 8 do. + 28 cwt. }| }the pound, |6,556 7 do. + | }burning two |5,194 6 do. + One Ton | }hours; or to |4,325 5 do. + One Sack | } |3,463 4 do. + One Bushel | } |2,595 3 do. + One Peck | } |1,730 2 do. + One Pound | } | 866 1 do. + -----------+----------------------------------------- + + COKE.--One chaldron of coal, from 25 to 28 cwt. gives 1-1/4 to 1-1/2 + chaldron of Coke. + + TAR.--One chaldron of coal, from 25 to 28 cwt. gives from 150 to + 180lb. of Tar,[39] or 15 to 18 ale gallons, 10lb. each. + + AMMONIACAL LIQUOR.--One chaldron of coal, gives from 220 to 240lb. of + Ammoniacal Liquor, or 22 to 24 ale gallons. + + [39] 1000lb. of Coal-Tar afford by distillation, from 260 to 265lb. of + Essential Oil, or Naphtha. 1000lb. of Coal-Tar produce by mere + evaporation, from 460 to 480lb. of Pitch. + +_Tabular View, exhibiting the illuminating power of Coal-Gas, compared +with the illuminating power of Tallow Candles of different sizes._ + + One chaldron of Coal produces, according to weight and quality, + Cubic feet of Gas. Average. Burning. Candles. 12 to 1lb. 6 to 1lb. + From 9,000 to 12,000 10,500 1 hour = 21,000 = 10,500 + ----- ------ ------ 2 hours = 10,500 = 5,250 + 6,000 8,000 7,000 3 ditto = 7,000 = 3,500 + 4,500 6,000 5,250 4 ditto = 5,250 = 2,625 + 3,600 4,800 4,400 5 ditto = 4,400 = 2,200 + 3,000 4,000 3,500 6 ditto = 3,500 = 1,750 + 2,571 3,428 3,005 7 ditto = 3,005 = 1,502 + 2,250 3,000 2,625 8 ditto = 2,625 = 1,312 + 2,000 2,666 2,333 9 ditto = 2,333 = 1,166 + 1,800 2,100 2,100 10 ditto = 2,100 = 1,050 + 1,636 2,191 1,913 11 ditto = 1,913 = 956 + 1,500 2,000 1,750 12 ditto = 1,750 = 875 + 1,384 1,846 1,615 13 ditto = 1,615 = 807 + 1,285 1,714 1,499 14 ditto = 1,499 = 749 + 1,200 1,600 1,400 15 ditto = 1,400 = 700 + 1,125 1,500 1,312 16 ditto = 1,312 = 656 + 1,058 1,111 1,234 17 ditto = 1,234 = 617 + 1,000 1,333 1,166 18 ditto = 1,166 = 583 + 947 1,263 1,105 19 ditto = 1,105 = 552 + 900 1,200 1,050 20 ditto = 1,050 = 525 + 857 1,143 1,000 21 ditto = 1,000 = 500 + 818 1,095 956 22 ditto = 956 = 478 + 783 1,044 913 23 ditto = 913 = 456 + 750 1,000 875 21 ditto = 875 = 437 + +N. B. If it be required to know, for how many hours one pound, or one +peck, or one bushel, or one sack, of coal will produce Gas Light equal +to that of a certain number of well-snuffed Tallow Candles, the +proportion of each of the average weights of a pound, peck, bushel, or +sack, to that of the average weight of a chaldron of coal, is as +follows: + + 1 lb. = 2968th part of a chaldron. + One peck 20 = 148th ditto. + One bushel 82 = 36th ditto. + One sack 248 = 12th ditto. + +RULE.--Divide with either of the above parts of weight, the number of +lights opposite to their hours, and the product will be the number of +lights burning for the same number of hours. + +EXAMPLE.--To know how many lights one peck of coal will give for six +hours, divide the 148th part in 3,500, opposite to the number of six +hours, the product is almost 24 lights. The same rule holds good for any +given quantity or number of pounds of coal, in a chaldron, to find how +many lights, or candles, 12 to the lb. or 6 to the lb. they will give +for a given number of hours. + + +DESCRIPTION OF THE GAS-LIGHT APPARATUS. + + +PLATE I. + +Exhibits a perspective view of a gas-light apparatus,[40] for lighting +factories, or small districts of houses. It consists of the following +parts: which may be considered separately. + + [40] This apparatus was erected by Mr. CLEGG, and is now in action at + Mr. ACKERMAN's establishment, in this metropolis. + +FIG. 1. The _Retort Furnace_, for distilling the coals. It is built of +brick-work. The bricks which are exposed to the immediate action of the +fire, are _Welch tumps_, or fire-bricks; they are bedded in clay, or +Windsor loam. + +FIG. 2. The _Tar Cistern_, to collect the coal-tar, and other +condensible products obtained during the distillation of the coals. It +is a cast-iron hollow cylinder, closed at the top with a cast-iron +cover, which has a very small hole to allow the air to escape as the +liquid enters into the vessel. + +FIG. 3. The _Lime Machine_, for purifying the crude coal-gas, and to +render it fit for use. The construction of this machine will be +explained in plate VII. It is put together of cast-iron plates. + +FIG. 4. The _Gasometer_, for collecting and preserving the purified gas, +and for distributing and applying it as occasion may require. It +consists of two principal parts--namely, a large interior vessel closed +at the top and open at the bottom, made of sheet iron, designed to +contain the gas, and an outer cistern or vessel, of rather greater +capacity, constructed of cast-iron plates, in which the former vessel is +suspended. The latter contains the water by which the gas is confined. +The interior vessel which contains the gas is suspended by chains hung +over wheels or pullies, to which weights are attached, so as to be just +sufficient to balance the weight of the gasometer, all but a small +difference, and allowing its slow descent in the manner which is found +as nearly adapted as can be to the proper supply of the lamps. The +weight of the chains must be equal to the specific gravity of the +material of which the gasometer is composed, so as to compensate +accurately for the quantity of water which the gasometer displaces, or +what is the same, it must be equal to the loss of weight which the +gasometer sustains, when immersed in the water; and the counterpoise +weight must be equal (or nearly so) to the absolute weight of the +gasometer. + +The action of these different parts of the apparatus will be obvious +from the following explanation: + +A, A, are two iron retorts, placed horizontally, and side by side, in +the furnace; the mouth of the retorts where the coals are introduced, +projects into an arched chamber, situated in front of the furnace, as +shewn in the drawing by the broken down brick-work. The object of +suffering the mouth of the retorts to project into a separate chamber, +is merely to discharge with convenience the red hot coke from the +retorts when the process is at an end; the coke being suffered to fall +to the bottom of the chamber, where it cools, without becoming +troublesome to the operator. It may be removed from this fire-safe +chamber by the door represented at the end view of the furnace. + +When the operation commences, the inner vessel of the gasometer, fig. 4 +is sunk down, to expel the air which it contains to a level with the +exterior vessel, or outer cistern, of the gasometer; and, consequently, +becomes filled with water. As the distillation of the coal in the +retorts proceeds, the liquid and gazeous products evolved from the coals +are transmitted by means of the perpendicular syphon pipes B, B, into +the horizontal pipe or main condenser C, with which they are connected. +The liquid which is distilled, collects in the pipe, or main condenser, +C, where it is retained until its quantity has risen so high as to +discharge itself into the pipe D, which is connected with the upper part +of one of the extremities of the condenser, C. One of the extremities of +the pipes, B, B, therefore become immersed into the liquid contained in +the main condenser or pipe C, whilst the vaporous or condensible fluid, +after having overcome the pressure there opposed to it, is transported +into the pipe E, which, after passing in a serpentine direction, E, E, +&c. through the exterior vessel or cistern of the gasometer, terminates +in the tar-vessel, fig. 2. Thus the vaporous fluids are condensed by +passing through the serpentine pipe, E, E, &c. and become deposited in +the tar-cistern, fig. 2; whilst the non-condensible or gazeous products +are made to proceed by the pipe F, which branches off from the pipe E, +into the lime machine, fig. 3. In this apparatus the gas, as it is +evolved from the coals, comes into contact with slaked lime and water; +the object of which is, to strip it of its sulphuretted hydrogen and +carbonic acid gas with which it always abounds, and to render it fit for +illumination. This being accomplished, the purified gas is conducted +away out of the lime machine by means of the pipe G, into the +perpendicular pipe H, which branches up through the bottom of the +gasometer cistern. The upper extremity of this pipe is covered, in the +manner of a hood, by a cylindrical vessel I, open at bottom, but +partially immersed beneath the surface of the water contained in the +outer cistern of the gasometer, it is also perforated round near the +lower edge with a number of small holes. The gas, as it passes out of +the pipe H, displaces the water from the receiver I, and escapes through +the small holes, and is thus made to pass through the water in the +cistern, in which the hood of the pipe I, is partly immersed, so as to +expose a large surface to its action, that it may once more be washed, +and deprived of all the foreign gazeous products which might have +escaped the action of the lime, whilst it was agitated with this +substance in the lime machine, fig. 3. After rising through the water in +the gasometer cistern, it enters into the gasometer, which then ascends +as the gas accumulates in it. + +In this manner the process proceeds, until the whole of the volatile +products of the coal in the retort are disengaged. The use of the +gasometer is, partly to equalize the evolution of the gas which comes +from the retort more quickly at some time than others. When this +happens, the vessel rises up to receive it, and when the stream from the +retort diminishes, the weight of the gasometer expels its contents, +provided the main-cock be open. When the process is finished, the retort +is suffered to cool, and its lid is then removed to replenish it with +coal. When the main stop-cock is then opened, the gasometer descends, +and the gas passes from the gasometer through the pipe K, to the +burners, or main pipe, which communicates with the gas burners or lamps. +L, is a wooden tub or barrel, containing the mixture of lime and water, +for charging the lime machine; and into which the contents of the +barrel, L, may be conveyed by the curved pipe M, without admitting +common air. N, N, is a water-pipe, to convey fresh water into the +gasometer cistern occasionally; because it is essential that the water +used for washing and purifying the gas should be changed for fresh as +soon as it becomes dirty; and unless this is done, the gas will not be +perfectly purified by washing, but produce a disagreeable odour when +burnt; the same holds good with regard to the lime machine, the +contents of which should be renewed occasionally. This pipe also conveys +the necessary water into the barrel, L. O, is a waste-pipe, to convey +the water as it becomes impregnated with the impurities of the gas, out +of the gasometer cistern. P, is an agitator, to stir up the contents of +the lime machine occasionally, Q, Q, are two iron rods, which serve as +stays to guide the motion of the gasometer. R, is an index, connected by +means of a shaft and pulley with the axis of one of the gasometer +wheels. This index is graduated to the capacity of the cubical contents +of the gasometer, so as to indicate, by the rising and falling of the +gasometer, its relative contents of gas expressed in cubic feet. S, is +the waste pipe of the lime machine, to remove the insoluble parts of the +lime. T, represents the iron cover, or lid, which is turned on the +lathe, and ground air-tight, to close up the mouth of the retort, so as +to make readily an air-tight fitting. U is an iron wedge to secure the +cover of the retort. The left-hand retort in the design shows the retort +closed up, and the cover, or lid of the mouth of it secured by means of +the wedge, in its place, so as to render the mouth of the retort +perfectly air tight. + +There is a safety valve attached to this gasometer which could not be +represented in the drawing; and the object of which is, to convey away +any portion of gas that might happen to be produced by a careless +operator, when the gasometer is full, and which is thus prevented from +accumulating in the place where the gasometer is erected. It is +represented in the right-hand corner of plate VII. where fig. 1 shows +the edge of the gasometer; 2, the surface of the water in the inside of +the gasometer; 3, the surface of the water in the outside of the +gasometer, or in the cistern; 4, a pipe issuing from the lower edge of +the gasometer, and surrounded at its upper extremity with a cup marked +5; 6, the waste pipe, the mouth of which is immersed in water. It is +obvious that, when the gasometer is full, if an additional quantity of +gas should be attempted to be put into it, it will be transported by +means of the pipe 4, into the waste-pipe 6; the upper extremity of which +reaches out of the building, and there communicates with the open air. + + +PLATE II. + +Represents a Portable experimental Gas Apparatus for exhibiting, in the +small way, the general nature of the gas-light illumination.--It is +described page 79. + + +PLATES III. IV. V. + +Show designs of various kinds of Gas Lamps, Chandeliers, Candelabras, +&c.--See pages 114, 118, 140. + + +PLATE VI. + +FIG. 1. Exhibits a design of the _gasometer framing_, or _skeleton_, +which serves to give stability and strength to the gasometer. It +consists of wooden frame work, marked A, A, A, interlaced with iron +rods, B, B, B, &c. The whole framing is so disposed that it will float +in the cistern horizontally, and therefore keep the gasometer perfectly +steady and level with the surface of the water. + +The rest of the sketches represent various kinds of gas pipes employed +as _mains_ for conveying the gas, and the methods of connecting them. + +FIG. 2. Represents a longitudinal section of a _Spigot_ and _Faucet +Pipe_. These kinds of pipes are applicable in most cases as mains for +conveying gas. A, is called the spigot, and B, the faucet. They are +joined together, and made air tight, by iron cement, the composition of +which is as follows: + +Take two ounces of sal ammoniac, one ounce of flowers of sulphur, and +sixteen ounces of cast iron filings or borings. Mix all well together, +by rubbing them in a mortar, and keep the powder dry. + +When the cement is wanted for use, take one part of the above powder, +and twenty parts of clean iron borings or filings, and blend them +intimately by grinding them in a mortar. Wet the compound with water, +and when brought to a convenient consistence, apply it to the joints +with a wooden or blunt iron spatula. + +By a play of affinities, which those who are at all acquainted with +chemistry will be at no loss to comprehend, a degree of action and +re-action takes place among the ingredients, and between them and the +iron surfaces, which at last causes the whole to unite as one mass. In +fact, after a time, the mixture and the surfaces of the flanches become +a species of pyrites (holding a very large proportion of iron,) all the +parts of which cohere strongly together. + +The inner parts of the faucet ought to be no larger in diameter than +just to fit the spigot. This supports the pipe, independently of the +cement, and prevents the risk of hurting the joint from any external +stress. The inner faucet is commonly made about 2-1/2 inches deep, and +has the spigot inserted 1-1/2 inch into it. The practice of some +workmen, is to make the outer faucet, or that which contains the cement, +six inches deep, for all pipes above six inches diameter; and to make +the faucets of all pipes below six inches, the same depth as the +diameter of the pipes. It is usual to make the space for the cement, all +round the spigot, from 1 to 1-1/2 inch; that width is required, in order +that the cement may be firmly driven into the joint. When the space is +very narrow, this cannot be done. On the other hand, when too wide, +there is a waste of cement, and a risk of injury from unequal expansion. + +FIG. 3. Exhibits a profile view of these kinds of pipes when joined +together. The spigot and faucet pipes are liable to burst from the great +expansion of the spigot, and the risk of this accident is increased by +increasing the space between the spigot and faucet, which requires to be +filled with cement. + +FIG. 4. Represents a longitudinal section of two flanch pipes, and the +modes of connecting them. A and B, show the parts of the pipes; and C +and D, the flanches. These pipes are also joined together, and rendered +air-tight, by interposing between the flanches rope-yarn, hemp, or some +other pliable material, and iron cement, and then screwing up the faces +of them by means of the bolts and screw nuts. + +FIG. 5. Profile view of the same kind of pipes connected together, A and +B, the pipes; C and D, the flanches; E and F, the bolts. + +FIG. 6. Represents the method of joining spigot and faucet pipes when +they are to have a turn or angle. This method is convenient when the +place where the turn required to be made is previously known, and the +pipes cast accordingly. + +FIG. 7. Exhibits the method of connecting spigot and faucet pipes when +they have a round turn. A and B, the junctures of the pipes. + +FIG. 8. Represents a longitudinal section of the mode of joining pipes +by means of what is called a _thimble joint_. The junctures of the pipes +to be connected, are made air tight, as mentioned already, by iron +cement. A, the thimble or small cylinder, with projecting edges, which +unites the pipes B, C. + +FIG. 9. A thimble joint made in two parts, which is sometimes convenient +to join pipes. The parts are joined together by screw bolts, and nuts, +in the usual manner. + +FIG. 10. Section of the same. + +FIG. 11. Represents a profile view of what is called the _saddle joint_. +It is employed for taking off a branch-pipe. The branch has a piece A B, +formed on its end, and fits round one-half of the outside of the pipe +from which it is to proceed. C, is called the saddle, which fits round +the other half of the pipe. The parts are secured together by screw +bolts, and iron cement. By this method a branch may be formed on any +part of a gas-pipe, by cutting a hole there, and applying the branch to +that place. Where there is much risk of the inequality of expansion, the +joints at certain places, should be secured by a soft stuffing of hemp +and tallow; but in most cases the joints may be made with iron cement. +Lead is frequently used for making the joints of gas pipes instead of +iron cement, though cheaper and more easy of repair. The galvanic action +which takes place between the lead and iron, soon renders the joints +leaky, and the danger is increased by the unequal expansion of the two +metals. + +FIG. 12. Section of the saddle-joint. + +Before the gas is suffered to enter into the pipe, they should be proved +to be sound, by the usual process of forcing water into them: The pipes +serving as mains, are placed perfectly solid, so that they cannot give +way; their course should be rectilinear, having a descent of about 1 +inch in 9 or 10 feet, to allow the water of condensation which may be +deposited from the gas by a change of temperature to collect readily at +the lowermost part. + +FIG. 13. Shows a reservoir for collecting the water of condensation +which might accumulate in the pipes. It consists of a receptacle, A, in +which the water may pass; B, a branch-pipe closed at the top, by means +of which the water may be removed, by drawing it out with a syringe. +This receptacle is placed in those situations where pipes incline +towards each other. + + +PLATE VII. + +Exhibits a perpendicular section of a gas-light apparatus, calculated +for lighting towns, or large districts of streets and houses. + +FIG. 1. The Retort Furnace. The retorts are placed over each other in +one or more rows; so that a certain number of them may be heated by +separate fire-places. A, A, shows two of the retorts placed horizontally +above each other; B, the fire-place; C, the flue which causes the fire +to circulate round the retorts so as to heat them equally in every part; +D, the opening of the flue where the fire passes into the chimney; E, +the ash-pit; F, a chamber in front of the retort furnace, into which the +orifice or mouth of the retorts project; G, G, the doors of the chamber, +to enable the workmen to charge and discharge the retorts; H, a funnel +shaped hole at the floor of the chamber F, through which the red hot +coke as it is discharged from the retorts passes into the arched vault +I; K, the syphon tube; L, the horizontal condenser[41]--the action of +both of these pipes have been already explained, p. 168; M, main pipe, +which conveys the liquid substances from the condenser, to the tar +cistern, fig. 3, and which conducts also the gazeous products into the +lime machine, fig. 2; N N, shows that part of the pipe which is +interposed between the tar cistern, fig. 3, and the condensing pipe +M,--it passes in a serpentine direction along the inner sides of the +gasometer cistern, and, like the so-called _worm_ in a distillatory +apparatus, condenses the products which escape in a vaporous state from +the condenser L; O, shows the place where the serpentine pipe N N, +passes again out of the gasometer cistern, and its communication with +the lime machine, fig. 2, and tar chamber, fig. 3. The action of the +lime machine is as follows: The liquid products evolved from the coal, +having been deposited in the tar cistern, fig. 3, by means of the +serpentine pipe N, N, the gazeous products which accompany it, are +conveyed by means of the pipe P, which branches out from the pipe O, +into the interior receptacle of the lime machine marked Q, which +consists of a vessel open at the bottom, and closed at the top, where it +communicates with the pipe O. As the gas accumulates in the interior +part Q, of the lime machine, it is made to pass through the liquid which +it contains, namely, slaked lime and water; and escapes through +appertures made in the horizontal partitions R, R, R, R, into the outer +vessel, S, of the lime machine and from thence it is conducted away by +the pipe T, T, T, into the additional washing apparatus, of the +gasometer; fig. 4, the construction of this apparatus, greatly resembles +the lime machine, fig. 2, namely, V, is a water pipe, proceeding from a +cistern U, placed 3 or 4 feet above the orifice of the pipe V; T, T, is +the gas-pipe, covered with a hood, marked W, and immersed in a small +cistern, having horizontal perforated shelves, like those in the lime +machine--they fit close to the hood. The gas which enters the hood W, +meets with a shower of water delivered by the pipe V. The gas, as it +passes through the holes in the horizontal partitions, is, therefore, +again washed and thoroughly purified from foreign gases which may have +escaped the action of the lime machine; Y, is a waste pipe, the lower +extremity of which is sealed by being immersed in water,--it serves to +carry away the water delivered by the pipe V, as it has been acted on by +the gas. The summary action of this gas apparatus is, therefore, as +follows: The liquid products obtained from the coal during the +distillation are first deposited in the main condenser L, by means of +the pipe K, and from whence they cannot escape until a quantity of tar +has accumulated in it to a certain height, and by this means, one of the +extremities of the pipes K, K, becomes immersed and hermetically sealed +by the liquid which the condenser L, contains. The liquid products, +after having accumulated to a certain height in the condenser, overflow +the perpendicular portion which it contains, and discharge themselves +into the pipe M, from whence they are transported into the tar cistern, +fig. 3, by means of the system of pipes N, N, O, whilst the gazeous +products are made to pass by means of the branch pipe P, into the lime +machine, fig. 2. From this part of the apparatus the gas passes through +the pipe T, T, T, into the additional or smaller washing apparatus +placed upon a tressel in the cistern of the gasometer, where it is +again exposed a second time to the action of a current of fresh water; +and from this vessel the gas ascends into the gasometer. The gasometer +is furnished with a pipe A, closed at the top, and fixed in one corner +of the gasometer, but open at the bottom; it includes another pipe +marked B, which communicates with the main pipe leading to the burners, +or place where the gas is wanted. The pipe A, which slides over the pipe +B, is perforated at the top, the gas passes through these perforations +and is thus made to enter into the pipe B, and disposed of as mentioned. +C, C, is a tube of safety adapted to the gasometer; its lower extremity +remains sealed by the water in the cistern so long as the gasometer is +not overcharged with gas; but, if more gas should be made to enter the +gasometer than it is destined to receive, this pipe then delivers the +gas into the funnel-shaped tube D, which reaches through the roof of the +gasometer house, and thus the superfluous quantity of gas is conveyed +away into the open air. + + [41] The condenser in this apparatus is placed at right angles to the + row, or rows of retorts. It is furnished at one extremity with a + partition placed perpendicularly, and of a height equal to about + one-half of the diameter of the condenser. The object of this + partition is to prevent the tar, &c. deposited in it, to seal the + pipes K, K, and not to discharge itself into the pipe M, till this has + been effected. The partition is seen in the drawing. + +The cylindrical vessel P, of fig. 3, surrounding the orifice of the pipe +O, which delivers the tar into the tar cistern, fig. 3, serves to keep +this pipe constantly immersed into a portion of tar, so that the +contents of the cistern may be drawn off by the cock without admitting +air into any part of the apparatus. The tar cistern has a small hole at +the top, to allow the air which it encloses to escape, as it becomes +filled with tar and ammoniacal liquor. The main condenser L, is placed, +as shown in the drawing, higher than the level of the water in the +gasometer cistern, to allow a free descent of the distillatory liquids +as they pass from this vessel along into the pipes M, N, O, &c. The +cistern of the gasometer, as well as the lime machine, and tar cistern, +are constructed of cast iron plates, bolted and cemented together with +iron cement. The gasometer is made of sheet iron plates rivetted +together--E, E, are two iron stays--G, G, are friction wheels. + + +_METHOD of correcting the relative pressure of the Gasometer, so as to +cause the gas which it contains to be uniformly of an equal +density._[42] + + [42] For this elegant contrivance we are also indebted to Mr. CLEGG. + +We have mentioned already that the pressure of the gas in the gasometer +should be invariable, for it is obvious that the weight of the gasometer +is constantly increasing in proportion as it fills with gas, and rises +out of the water--see p. 88, and 167. To render its pressure uniform, we +first take the _absolute_ weight of that part of the gasometer which +becomes immersed in the water, and knowing the _specific weight_ of the +substance of which it is composed, we divide its absolute weight by the +specific weight of the substance of which it is composed; and this being +done, we make part of the chain, (measured at right angles from the axis +of the wheels over which it passes downwards towards the top of the +gasometer,) which is equal to the length of that part of the gasometer +which becomes immersed in water, equal in weight to the specific gravity +of the substance of which the gasometer is composed. For example, let +us suppose that the part of the gasometer which becomes immersed in +water weighs 861 _lb._ and that it is composed of sheet iron, the +specific gravity of which, in round numbers, we will take to be 7. It is +then evident, that the part of the chain of the gasometer measured +downward from the axis of the wheel over which it passes, and which is +equal in length to the height of the gasometer, must be loaded with a +weight of, or must itself weigh, 123_lb._ for this would be the weight +of the water displaced by the gasometer; or let us suppose the gasometer +to be made of sheet copper, the specific weight of which (omitting +decimals) is 8; and that the absolute weight of the gasometer is +1792_lbs._ then the chain of the gasometer equal in length to the height +of the gasometer, immersed into the water must weigh 224_lb._ for this +would be the weight of the quantity of water which the gasometer +displaces. This being accomplished by then adding or diminishing the +absolute or balance weight of the gasometer, any desired uniform +pressure may be effected, and the same bulk of gas will always be of the +same specific gravity. + + +DIRECTIONS TO WORKMEN ATTENDING THE GAS-LIGHT APPARATUS[43]. + + [43] Copied from a printed direction drawn up by Mr. Clegg, for the + use of workmen. + +Particular care must be taken to make the joints of the mouth-pieces of +the retorts perfectly air tight, which may be done in the following +manner:--Take some common clay, dry, pulverize, and sift it, then add +as much water as will make it into the consistency of treacle; make the +mouth-piece and the lid of the retort clean, lay this luting thinly over +the turned part of the lid, press the lid so luted gently to the +mouth-piece, and then secure it moderately, by means of the iron wedge: +if the workman observes this rule, he will never fail to make good +joints; but if, on the other hand, the operator is careless and neglects +to remove the old luting, &c. from the turned or smooth part of the +mouth of the retort, and thereby cause a bad joint, the consequence will +be the loss of a considerable quantity of gas, and a very disagreeable +smell and smoke. + +The bridge or row of bricks of the flue C, of the retorts, should never +be made hotter than a bright red, which may be regulated by the door of +the ash-pit being kept close shut when the fire is getting too hot. If +the operator neglects this, and suffers the fire-bricks to arrive at a +bright white heat the retorts will soon be destroyed, and bad gas be +produced. + +The gasometer should be well examined, at least once a week, to see if +it leaks, by the following method, viz. Let the main stop-cock be shut, +then make a mark on the gasometer at the water's edge when it is full or +nearly of gas, there being no gas coming from the retorts at the time, +and if the mark sinks in the water, the gasometer leaks; to find out the +place, walk slowly round it, and you may perceive the leak by the smell, +apply a lighted candle to the part suspected, and if there be gas +issuing from it, it will take fire, and perhaps appear like a small +blue flame--blow it out, and mark the place: thus proceed round the +gasometer till you have found all the places; if you perceive a smell, +and yet cannot produce a flame in the part suspected, take a brush with +a little thin white-lead paint, and lay it on the part where you think +the leak is, and, if it be there, the gas which escapes from the leak, +will immediately turn the paint brown. After the sides of the gasometer +have been well examined, and secured by dipping a piece of cloth about +the size of a shilling, into some melted pitch, tempered with a little +bees-wax and tar, apply the cloth whilst hot to the place with the end +of your finger, rubbing it till it is quite cold; next examine the top +of the gasometer in the same manner,--when it is about two feet high in +the cistern, it will then be better to get at. The water in the cistern +should always be kept within 3 or four inches of the top, if suffered to +sink much lower without replenishing, the gas will not pass through a +sufficient quantity of water, and oily particles will be apt to condense +in the pipes, to their great detriment. + +The only thing to be observed in the place lighted is, that the lamps +and pipes are not suffered to be touched on any pretence whatever, but +by the person entrusted with their care. When a lamp is not wanted, it +must be completely shut off from the pipe which supplies it, by a +stop-cock provided for the purpose, and not opened again but when a +flame is held over it; not a lighted candle, as the tallow is liable to +drop into the lamps; lighted paper is better. + + +ESTIMATE OF THE PRICE OF A GAS-LIGHT APPARATUS, _IF ERECTED IN LONDON_, + +Capable of affording, every 24 hours, Light equal to 40,000 Tallow +Candles, six in the pound, burning one hour. + + £. s. + Gasometer, to contain 10,000 cubic feet of gas 236 0 + + Wheel-work, regulating chain, ballance-weight for } 160 11 + ditto, with wooden framing } + + Wrought iron cistern for gasometer--36 feet wide, } 500 0 + 24 feet long and 16 feet deep } + (_It would weigh about 16 tons._) + + Wooden framing built around it, to secure ditto 150 0 + + Condenser, cistern and communicating pipes 126 0 + + Lime machine, made of cast iron plates 82 0 + + Gasometer-house, built of frame-work and weather-boarded 250 0 + + Twenty-four retorts set in brick-work, with furnaces } 336 0 + for ditto, compleat } + + Sundries 100 0 + --------- + £ 1940 11 + + * * * * * + + A gas-light apparatus complete for work, capable of affording every + twenty-four hours a quantity of light equal to 1,400 Argand's Lamps, + each lamp equal in intensity to six candles, six in the pound, burning + for five hours, will cost 3,500_l._ if erected in this metropolis. + + +LONDON Price List of the most essential articles[44] employed in the +erection of a Gas-Light apparatus. + + [44] All the articles are warranted to be perfect and of the best + kind. They are delivered free of expence at any wharf between London + and Westminster-bridge. + + Sheet-iron pipes brazed. + _s._ _d._ + 1/4 inch in diameter 0 4 a foot} + 3/8 ditto 0 4 ditto} + 1/2 ditto 0 5 ditto} + 5/8 ditto 0 6 ditto} + 3/4 ditto 0 6-1/2 ditto} in + 7/8 ditto 7 ditto} 15 + 1 inch, ditto 0 7-1/2 ditto} to + 1-1/4 ditto 0 9 ditto} 18 + 1-1/2 ditto 0 10-1/2 ditto} feet + 1-3/4 ditto 0 11 ditto} lengths. + 2 inch, ditto 1 1-1/2 ditto} + 2-1/4 ditto 1 4 ditto} + 2-1/2 ditto 1 5 ditto} + 3 inch, ditto 1 6-1/2 ditto} + Copper pipes brazed 1/4 inch 0 4 per foot + Ditto, ditto, ditto 3/8 inch 0 5-1/2 ditto + Gas-light cockspur burners with stop-cock 2s 6d to 3s 6d + Argand's lamps, with glass-holders, from 3s to 4s 6d + Cast-iron retorts, weighing 7 cwt. at 15s 6d per cwt £5 8 6 + Mouth-piece for ditto, compleat 1 14 8 + Cast-iron door frames for retort furnace 1 0 0 + Furnace bars 10s. per cwt. + Sheet iron for gazometer (No. 23) 24s. per cwt. + Gazometer chains, 5d per lb. + Ballance weights [Plates] for gazometer, 9l 10s per ton. + Cast-iron cistern plates + ------------------------ smaller size for lime machine, 18l per ton. + ------------------------ middling size for tar cistern, 16l ditto + ------------------------ largest size for gazometer cistern 14l ditto + Cast-iron flanch pipes 2-inch diameter, at 5s per yd. in 6 feet lengths + ditto 3 ditto 6s ditto 6 ditto + ditto 4 ditto 8s 6d ditto 9 ditto + ditto 5 ditto 10s ditto 9 ditto + ditto 6 ditto 12s ditto 9 ditto + ditto 7 ditto 13s 6d ditto 9 ditto + ditto 8} + ditto 9} 11l. 5s. per ton 9 ditto + ditto 10} + ditto 11} + 1/2 inch nuts, screws and washers to put iron pipes together 7d. per lb + 5/8 ditto 7d. ditto + 3/4 ditto 6d. ditto + English bar-iron 13l. per ton + Best, ditto 18l. ditto + + +_FINIS._ + +[Illustration: Fig. 1 + +_London Pub. April 1-1815, at R·Ackermann's, 101 Strand._] + +[Illustration] + + + + +Transcriber's notes + +The entries in the Table of Contents do not always conform to the +chapter and section headings in the text. Both have been retained as in +the original work. + +The errata have already been incorporated in the text; the error +mentioned as occurring on page 24 actually occurs on page 22. + +The original language, including inconsistencies in spelling, +hyphenation, punctuation, formatting, etc. has been retained, except as +mentioned below. + +Unclear parts of the text have been checked against the on-line copy of +this book of the Eidgenössische Technische Hochschule Zürich. + +Fractions like 1/2 and 1-10th have both been retained. + +Page 90, Van Dieman, Troostwyck: Jan Rudolph Deiman and Adriaan Paets +van Troostwijk. + +Changes made to the text: + +Obvious punctuation and typographical errors have been corrected +silently. + +Some footnotes, tables and illustrations have been moved; some tables +have been re-arranged. + +Other changes: + +Page 23: any surfaces changed to any surface + +Page 26: opening or shuting changed to opening or shutting + +Page 47: A New changed to A new + +Page 48: trafic changed to traffic; footnote [10]: corporated changed to +incorporated (cf. errata) + +Page 53: This combustion changed to The combustion (cf. errata) + +Page 64: Cleg changed to Clegg (cf. errata); footnote anchor [14] moved +from next page (cf. errata, footnote anchor *); communicates changed to +communicated (cf. errata) + +Page 67: 1250 + 2 = 2500 changed to 1250 × 2 = 2500 + +Page 69: Mr. LEE changed to "Mr. LEE for consistency + +Page 72: closing quote mark added to letter + +Page 96: pure coal- changed to pure coal-gas + +Page 102: sub acetate changed to sub-acetate + +Page 118: ball 6 changed to ball _b_ + +Page 119: _e_, are changed to _e_ _e_, are + +Page 125: 180 degree changed to 180 degrees (cf. errata); footnote [28]: +may he compleatly changed to may be compleatly + +Page 131: and make changed to and makes + +Page 132: coal changed to coal-tar (cf. errata) + +Page 158: Nortou Falgate changed to Norton Falgate; a about changed to +about + +Page 165, table: 10,509 changed to 10,500. + + + + + +End of the Project Gutenberg EBook of A Practical Treatise on Gas-light, by +Fredrick Accum + +*** END OF THIS PROJECT GUTENBERG EBOOK A PRACTICAL TREATISE ON GAS-LIGHT *** + +***** This file should be named 44567-8.txt or 44567-8.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/4/4/5/6/44567/ + +Produced by Chris Curnow, Harry Lamé and the Online +Distributed Proofreading Team at http://www.pgdp.net (This +file was produced from images generously made available +by The Internet Archive) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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