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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text diff --git a/44567-0.txt b/44567-0.txt new file mode 100644 index 0000000..407369d --- /dev/null +++ b/44567-0.txt @@ -0,0 +1,4563 @@ +*** START OF THE PROJECT GUTENBERG EBOOK 44567 *** + +Transcriber’s notes + +Italics in the original work are transcribed between _underscores_; +small-capitals have been transcribed as all capitals. + +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 1½ | 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 15¾ | 1 | 8 | + | 3 {| 3 | 3 0 | 1 2 | 1⅛ | 8¾ | + | {| Mould | 3 0 | 0 0 | 1 | 9 | + +-----------+--------+--------+----------+--------+---------+ + | 4 {| 5 | 3 0 | 1 5 | 1.18 | 8¾ | + | {| Mould | 3 0 | 1 1⅛ | 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| 18¾ | 0 14 | 3 15 | 59 26 | 9.70 | + |wick. | 19 | 0 13½ | 2 40 | 50 34 | 11.40 | + |A large| 16½ | 0 15½ | 2 40 | 44 2 | 13.08 | + |wick. | 12 | 1 5¼ | 3 27 | 41 24 | 13.92 | + | | 10¾ | 1 8 | 3 36 | 38 24 | 15.00 | + | | 7¾ | 2 1 | 4 9 | 32 12 | 17.88 | + | | 8 | 2 0 | 4 15 | 34 0 | 16.94 | + | | 5¾ | 2 13 | 5 19 | 30 15 | 19.06 | + | |Mould | | | |Moulds at 14d. | + | |candles. | Each. | | | per dozen. | + |With | 3⅞ | 2 12 | 7 20 | 42 39 | 15.74 | + |wax’d | 4 | 4 0 | 9 3 | 36 20 | 18.56 | + |wick. | 3 | 5 2¾ |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 +13½_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 4¾ pecks of + coke and ½ 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 = +17½lbs. 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. ½7 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 | 3½ to 5_d_ -- 4¼ + One Pound | ¼ + -----------+------------------------------------------ + + -----------+----------------------------------- + | _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 -- 82½ + One Peck | 19½ to 21¼ -- 20¼ + 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 -- 71½ + One Pound | 3 to 4 -- 3½ + -----------+-------------------------------- + + -----------+----------------------------------------- + | } |_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 1¼ to 1½ + 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 2½ inches deep, and has +the spigot inserted 1½ 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 1½ 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._ + ¼ inch in diameter 0 4 a foot} + ⅜ ditto 0 4 ditto} + ½ ditto 0 5 ditto} + ⅝ ditto 0 6 ditto} + ¾ ditto 0 6½ ditto} in + ⅞ ditto 7 ditto} 15 + 1 inch, ditto 0 7½ ditto} to + 1¼ ditto 0 9 ditto} 18 + 1½ ditto 0 10½ ditto} feet + 1¾ ditto 0 11 ditto} lengths. + 2 inch, ditto 1 1½ ditto} + 2¼ ditto 1 4 ditto} + 2½ ditto 1 5 ditto} + 3 inch, ditto 1 6½ ditto} + Copper pipes brazed ¼ inch 0 4 per foot + Ditto, ditto, ditto ⅜ inch 0 5½ 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} + ½ inch nuts, screws and washers to put iron pipes together 7d. per lb + ⅝ ditto 7d. ditto + ¾ 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 ½ 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 THE PROJECT GUTENBERG EBOOK 44567 *** diff --git a/44567-h/44567-h.htm b/44567-h/44567-h.htm new file mode 100644 index 0000000..67d3639 --- /dev/null +++ b/44567-h/44567-h.htm @@ -0,0 +1,8043 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> + <head> + <meta http-equiv="Content-Type" content="text/html;charset=UTF-8" /> + <meta http-equiv="Content-Style-Type" content="text/css" /> + <title> + The Project Gutenberg eBook of A Practical Treatise On Gas-light, by Frederick Accum. + </title> + <link rel="coverpage" href="images/cover.jpg" /> + <style type="text/css"> + + .bb {border-bottom: solid thin;} + .bl {border-left: solid thin;} + blockquote {font-size: .9em; 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MEMBER OF THE ROYAL<br /> +IRISH ACADEMY, FELLOW OF THE LINNÆN SOCIETY, MEMBER<br /> +OF THE ROYAL ACADEMY OF SCIENCES OF BERLIN, &c. &c.</span></p> + +<hr class="sect" /> + +<p class="center fsize125">WITH SEVEN COLOURED PLATES.</p> + +<hr class="sect" /> + +<p class="center"><span class="oldtype fsize125">London:</span><br /> +<span class="fsize80">PRINTED BY G. HAYDEN, BRYDGES-STREET, COVENT GARDEN;<br /> +FOR R. ACKERMANN, 101, STRAND;<br /> +<i>LONGMAN, HURST, REES, ORME, AND BROWN; AND SHERWOOD, NEELY, AND<br /> +JONES, PATERNOSTER ROW; AND J. HATCHARD, PICCADILLY</i>.</span></p> + +<p class="center"><em class="italic">Price—Twelve Shillings in Boards.</em></p> + +<hr class="sect" /> + +<p class="center">1815.</p> + +<hr class="chap" /> + +<p class="motto center">EX FUMO DARE LUCEM.</p> + +<p class="motto right"><span class="smcap">Hor.</span></p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_i1" id="Page_i1">[i]</a></span></p> + +<h2>PREFACE.</h2> + +<p class="rightsig"><i>11, Compton Street Soho.</i></p> + +<p>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 <span class="smcap">Gas-Light</span>.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_ii1" id="Page_ii1">[ii]</a></span> +products it furnishes—the modes of obtaining +them—their properties and applications in the various +arts of life.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_iii1" id="Page_iii1">[iii]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p class="rightsig gesp blankabove">FREDRICK ACCUM</p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_i2" id="Page_i2">[i]</a></span></p> + +<h2 class="oldtype">Contents.</h2> + +<table class="toc" summary="ToC"> + +<tr> +<td class="secname"><b>INTRODUCTORY OBSERVATION.</b></td> +<td class="pagenr">Page</td> +<td class="pagenr"><a href="#Page_1">1.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.—Extraordinary discoveries of modern +times.—New art of procuring light.—Object of the treatise.</td> +</tr> + +<tr> +<td colspan="3" class="partnr">PART I.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>PRODUCTION OF ARTIFICIAL LIGHT, &c.</b></td> +<td class="pagenr"><a href="#Page_8">8.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>METHOD OF ASCERTAINING THE ILLUMINATING +POWER OF CANDLES, LAMPS, AND +OTHER LUMINOUS BODIES.</b></td> +<td class="pagenr"><a href="#Page_22">22.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="3" class="partnr">PART II.<span class="pagenum"><a name="Page_ii2" id="Page_ii2">[ii]</a></span></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>GAS-LIGHT.</b></td> +<td class="pagenr"><a href="#Page_47">47.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>THEORY OF THE COMBUSTION OF COAL IN +ELUCIDATION OF THE NATURE OF GAS-LIGHT.</b></td> +<td class="right bot"><a href="#Page_49">49.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>HISTORICAL SKETCH OF THE RISE AND PROGRESS +OF THE APPLICATION OF COAL-GAS +AS A SUBSTITUTE FOR PROCURING ARTIFICIAL +LIGHT.</b></td> +<td class="pagenr"><a href="#Page_55">55.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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. <span class="smcap">Clayton</span>, +Dr. <span class="smcap">Hales</span>, and the Bishop of Llandaff.—First successful +attempt of lighting manufactories with gas.—<em class="italic">Creditor</em> and <em class="italic">debtor</em> +account concerning the expence of this mode of illumination, +when compared with the light obtained by tallow candles.—Claims +of Mr. <span class="smcap">Murdoch</span> with regard to the economical application +of coal-gas.—Claims of Mr. <span class="smcap">Winsor</span>.—Experiments +of Mr. <span class="smcap">Northern</span>, Mr. <span class="smcap">Clegg</span>, Mr. <span class="smcap">Cook</span>, Mr. <span class="smcap">Ackermann</span>.—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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>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.</b><span class="pagenum"><a name="Page_iii2" id="Page_iii2">[iii]</a></span></td> +<td class="pagenr"><a href="#Page_77">77.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>UTILITY OF THE GAS-LIGHT ILLUMINATION +WITH REGARD TO PUBLIC AND PRIVATE +ECONOMY.</b></td> +<td class="pagenr"><a href="#Page_99">99.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">Objects to which the new system of lighting with gas may be beneficially +applied.—Capital advantages of the gas-light illumination.—Places +and public edifices lighted with coal-gas in this metropolis.—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 observations +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 obtainable from coal +besides gas.—<em class="italic">Coke.</em>—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.—Disadvantages +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 producing 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 +<span class="pagenum"><a name="Page_iv2" id="Page_iv2">[iv]</a></span>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.—<em class="italic">Coal tar.</em>—How obtained.—Its properties.—Earl +of Dundonald’s method of manufacturing 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.—<em class="italic">Coal +pitch.</em>—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.—<em class="italic">Ammoniacal liquor</em> 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.—Management 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 concerning 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, +<span class="pagenum"><a name="Page_v2" id="Page_v2">[v]</a></span>&c.—Produce no embers or sparks.—Cannot fall, or be disturbed +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-extinguishing lamp, invented by Mr. <span class="smcap">Clegg</span>.—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 <em class="italic">main</em>.—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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>TABULAR VIEW</b>, Exhibiting the quantity of <span class="smcap">Gas</span>, <span class="smcap">Coke</span>, +<span class="smcap">Tar</span>, <span class="smcap">Pitch</span>, <span class="smcap">Essential Oil</span>, and <span class="smcap">Ammoniacal Liquor</span>, obtainable +from a given quantity of <span class="smcap">Coal</span>: 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.</td> +<td class="pagenr"><a href="#Page_164">164.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>DESCRIPTION OF THE GAS-LIGHT APPARATUS.</b></td> +<td class="pagenr"><a href="#Page_166">166.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>METHOD</b> of correcting the relative pressure of the Gasometer, +so as to cause the gas which it contains to be uniformly of an +equal density.</td> +<td class="pagenr"><a href="#Page_181">181.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>DIRECTIONS TO WORKMEN ATTENDING THE +GAS-LIGHT APPARATUS.</b></td> +<td class="pagenr"><a href="#Page_182">182.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>ESTIMATE</b> of the price of a Gas-Light Apparatus.</td> +<td class="pagenr"><a href="#Page_185">185.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>LONDON</b> Price List of the most essential articles employed in +the erection of a Gas-light Apparatus.</td> +<td class="pagenr"><a href="#Page_186">186.</a></td> +</tr> + +</table> + +<hr class="sect" /> + +<h2 class="small">ERRATA.</h2> + +<table class="fsize80" summary="Errata"> + +<tr> +<td class="left top padr1">Page</td> +<td class="right top">24,</td> +<td class="left top padl1 padr1">line</td> +<td class="right top">11,</td> +<td class="left top padl1"><em class="italic">for</em> too, <em class="italic">read</em> two.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">48,</td> +<td> </td> +<td class="right top">22,</td> +<td class="left top padl1"><em class="italic">for</em> corporated, <em class="italic">read</em> incorporated.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">53,</td> +<td> </td> +<td class="right top">7,</td> +<td class="left top padl1"><em class="italic">for</em> this combustion, <em class="italic">read</em> the combustion.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">64,</td> +<td> </td> +<td class="right top">24,</td> +<td class="left top padl1"><em class="italic">for</em> <span class="smcap">Cleg</span>, <em class="italic">read</em> <span class="smcap">Clegg</span>.</td> +</tr> + +<tr> +<td> </td> +<td class="right top"><em class="italic">ibid</em></td> +<td> </td> +<td class="right top">25,</td> +<td class="left top padl1"><em class="italic">for</em> communicates, <em class="italic">read</em> communicated.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">65,</td> +<td colspan="2"> </td> +<td class="left top padl1">erase the * and put it after the word <span class="smcap">Clegg</span>, line 24, p. 64.</td> +</tr> + +<tr> +<td> </td> +<td class="right top"><em class="italic">ibid</em></td> +<td> </td> +<td class="right top">17,</td> +<td class="left top padl1"><em class="italic">for</em> attemps, <em class="italic">read</em> attempts.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">125,</td> +<td> </td> +<td class="right top">23,</td> +<td class="left top padl1"><em class="italic">for</em> degree, <em class="italic">read</em> degrees.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">132,</td> +<td> </td> +<td class="right top">25,</td> +<td class="left top padl1"><em class="italic">for</em> coal, <em class="italic">read</em> coal-tar.</td> +</tr> + +</table> + +<hr class="sect" /> + +<h2 class="small">DIRECTIONS TO THE BINDER:</h2> + +<p class="fsize80"><a href="#Plate1">Plate I.</a> facing the title; <a href="#Plate2">plate II.</a> facing page 79; <a href="#Plate3">plate III.</a> facing page 115; +<a href="#Plate4">plate IV.</a> facing page 119; <a href="#Plate5">plate V.</a> facing page 120; and <a href="#Plate6">plates VI.</a> +and <a href="#Plate7">VII.</a> at the end of the book.</p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_1" id="Page_1">[1]</a></span></p> + +<p class="pseudoh1">A<br /> +<span class="fsize150">PRACTICAL TREATISE</span><br /> +ON<br /> +<span class="fsize175">GAS-LIGHT.</span></p> + +<hr class="chap" /> + +<h2>INTRODUCTORY OBSERVATION.</h2> + +<hr class="sect" /> + +<h3>INFLUENCE<br /> +<span class="fsize60">OF</span><br /> +THE PROGRESS OF THE ARTS<br /> +<span class="fsize60">UPON THE</span><br /> +MORALS AND CONDITION OF MAN.</h3> + +<p class="largecap">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<span class="pagenum"><a name="Page_2" id="Page_2">[2]</a></span> +civilization is, and ought ever to be, estimated +by the proportional state of industry, and useful +labour existing among them.</p> + +<p>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 <span class="smcap">Smith</span><a name="FNanchor_1" id="FNanchor_1"></a><a href="#Footnote_1" class="fnanchor">[1]</a> +emphatically remarks, that “the accommodation +of an European prince does not +always so much exceed that of an industrious<span class="pagenum"><a name="Page_3" id="Page_3">[3]</a></span> +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.”</p> + +<div class="footnote"> + +<p><a name="Footnote_1" id="Footnote_1"></a><a href="#FNanchor_1"><span class="label">[1]</span></a> Wealth of Nations, chap. 1.</p></div> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_4" id="Page_4">[4]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_5" id="Page_5">[5]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_6" id="Page_6">[6]</a></span> +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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_7" id="Page_7">[7]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_8" id="Page_8">[8]</a></span></p> + +<h2>PART I.</h2> + +<hr class="chap" /> + +<h3>PRODUCTION<br /> +<span class="fsize60">OF</span><br /> +ARTIFICIAL LIGHT;<br /> +<span class="fsize60">AND</span><br /> +<span class="gesp">THEORY</span><br /> +<span class="fsize60">OF THE</span><br /> +ACTION OF CANDLES AND LAMPS.</h3> + +<p>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<span class="pagenum"><a name="Page_9" id="Page_9">[9]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_10" id="Page_10">[10]</a></span> +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.</p> + +<p>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,<span class="pagenum"><a name="Page_11" id="Page_11">[11]</a></span> +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.</p> + +<p>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.</p> + +<p>That in many cases the light evolved by artificial +means is derived from the combustible<span class="pagenum"><a name="Page_12" id="Page_12">[12]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_13" id="Page_13">[13]</a></span> +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.<a name="FNanchor_2" id="FNanchor_2"></a><a href="#Footnote_2" class="fnanchor">[2]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_2" id="Footnote_2"></a><a href="#FNanchor_2"><span class="label">[2]</span></a> See Chemical Amusement, comprising minute instructions +for performing a series of striking and interesting +chemical experiments, p. 8, &c.</p></div> + +<p>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<span class="pagenum"><a name="Page_14" id="Page_14">[14]</a></span> +the new system of illumination which it is the +object of this Essay to explain.</p> + +<p>To procure light for the ordinary purposes +of life, we are acquainted with no other ready +means than the process of combustion.</p> + +<p>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.</p> + +<p>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.</p> + +<p>All these substances must be rendered volatile +before they can produce a flame, but for +this purpose it is sufficient to volatilize a small<span class="pagenum"><a name="Page_15" id="Page_15">[15]</a></span> +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 <em class="italic">wick</em>, +which in fact is the fire-place, or laboratory +where the whole operation is conducted.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_16" id="Page_16">[16]</a></span> +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,<span class="pagenum"><a name="Page_17" id="Page_17">[17]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_18" id="Page_18">[18]</a></span> +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<span class="pagenum"><a name="Page_19" id="Page_19">[19]</a></span> +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<span class="pagenum"><a name="Page_20" id="Page_20">[20]</a></span> +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<span class="pagenum"><a name="Page_21" id="Page_21">[21]</a></span> +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. +<span class="smcap">Nicholson</span><a name="FNanchor_3" id="FNanchor_3"></a><a href="#Footnote_3" class="fnanchor">[3]</a> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_3" id="Footnote_3"></a><a href="#FNanchor_3"><span class="label">[3]</span></a> Philosophical Journal, 4to Series, Vol. I. p. 70.</p> + +</div> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_22" id="Page_22">[22]</a></span></p> + +<h3>METHOD<br /> +<span class="fsize60">OF</span><br /> +ASCERTAINING THE ILLUMINATING POWER<br /> +<span class="fsize60">OF</span><br /> +CANDLES, LAMPS, GAS-LIGHTS,<br /> +<span class="fsize60">AND</span><br /> +OTHER LUMINOUS BODIES.</h3> + +<p>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.</p> + +<p>For this purpose it is assumed as a principle, +that the same quantity of light, diverging in<span class="pagenum"><a name="Page_23" id="Page_23">[23]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_24" id="Page_24">[24]</a></span> +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;</p> + +<div class="figcenter"> +<img src="images/illo037.png" alt="Overlapping shadows" width="200" height="133" /> +</div> + +<p><span class="pagenum"><a name="Page_25" id="Page_25">[25]</a></span></p> + +<p>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<span class="pagenum"><a name="Page_26" id="Page_26">[26]</a></span> +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.</p> + +<p>From experiments made by Count <span class="smcap">Rumford</span>, +concerning the quantity of materials requisite +for producing a light of a certain intensity for<span class="pagenum"><a name="Page_27" id="Page_27">[27]</a></span> +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.<a name="FNanchor_4" id="FNanchor_4"></a><a href="#Footnote_4" class="fnanchor">[4]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_4" id="Footnote_4"></a><a href="#FNanchor_4"><span class="label">[4]</span></a> 112lbs. of Newcastle coal, called Tanfield Moor, produce, +upon an average, from 250 to 300 cubic feet of gas, +fit for illumination.</p></div> + +<hr class="sect" /> + +<h4>FURTHER ILLUSTRATIONS<br /> +<span class="fsize60">OF THE</span><br /> +<span class="fsize60">MODE OF COMPUTING THE RELATIVE COST OR VALUE</span><br /> +<span class="fsize60">OF</span><br /> +LIGHT,<br /> +<span class="fsize60">EMITTED BY MEANS OF</span><br /> +CANDLES, LAMPS, & OTHER BODIES.</h4> + +<p>It is sufficiently known that the light of a +candle, which is so exceedingly brilliant when +first snuffed, is very speedily diminished to<span class="pagenum"><a name="Page_28" id="Page_28">[28]</a></span> +one-half and is usually not more than one-fifth +or one-sixth before the uneasiness of the eye +induces us to snuff it.<a name="FNanchor_5" id="FNanchor_5"></a><a href="#Footnote_5" class="fnanchor">[5]</a> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_5" id="Footnote_5"></a><a href="#FNanchor_5"><span class="label">[5]</span></a> Ezekiel Walker.—Nicholson’s Journal, Vol. IV. 8vo. +Series.</p></div> + +<p>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.</p> + +<p>To prove the truth of this position, Mr. +Walker made the experiments contained in +the following</p> + +<p><span class="pagenum"><a name="Page_29" id="Page_29">[29]</a></span></p> + +<p class="center">TABLE.</p> + +<table class="nowrap" summary="Table page 29"> + +<tr class="bt bb"> +<th colspan="4" class="center padl1 padr1 bl br">No. of<br />the<br />Experi-<br />ment.</th> +<th class="center padl1 padr1 br">No. of the<br />Candles.</th> +<th colspan="2" class="center padl1 padr1 br">Time of<br />burning.</th> +<th colspan="3" class="center padl1 padr1 br">Weight<br />of the<br />Candles<br />consumed<br />in a given<br />time.</th> +<th colspan="2" class="center padl1 padr1 br">Strength<br />of Light.</th> +<th colspan="2" class="center padl1 padr1 br">Distance<br />of the<br />Candles<br />from the<br />Wall.</th> +</tr> + +<tr> +<th colspan="4" class="bl br"> </th> +<th class="br"> </th> +<th class="center padl1 padr1">h.</th> +<th class="br"> </th> +<th class="center padl1 padr1">oz.</th> +<th colspan="2" class="center padl1 padr1 br">dr.</th> +<th colspan="2" class="br"> </th> +<th colspan="2" class="center padl1 padr1 br">Feet.</th> +</tr> + +<tr> +<td rowspan="3" class="right padl1 padr1 bl">1</td> +<td rowspan="3" class="right padr0 narrow">-</td> +<td rowspan="3" class="bt bb bl narrow"> </td> +<td rowspan="3" class="br narrow"> </td> +<td class="center padl1 padr1 br">1</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">7</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">3</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr0">1</td> +<td class="center padl1 padr1 br">+</td> +<td class="right padl1 padr0">7</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">Mould</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">7</td> +<td class="br"> </td> +</tr> + +<tr class="thinrow bb"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr class="thinrow"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr> +<td rowspan="3" class="right padl1 padr1 bl">2</td> +<td rowspan="3" class="right padr0">-</td> +<td rowspan="3" class="bt bb bl"> </td> +<td rowspan="3" class="br"> </td> +<td class="center padl1 padr1 br">1</td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr1 br">55</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">3</td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr1 br">55</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">0</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="center padl1 padr1 br">+</td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">Mould</td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr1 br">55</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr class="thinrow bb"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr class="thinrow"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr> +<td rowspan="3" class="right padl1 padr1 bl">3</td> +<td rowspan="3" class="right padr0">-</td> +<td rowspan="3" class="bt bb bl"> </td> +<td rowspan="3" class="br"> </td> +<td class="center padl1 padr1 br">1</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">3</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">2</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>8</sub></td> +<td class="right padl1 padr0">8</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +</tr> + +<tr> +<td class="center padl1 padr1 br">Mould</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">0</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">9</td> +<td class="br"> </td> +</tr> + +<tr class="thinrow bb"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr class="thinrow"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr> +<td rowspan="2" class="right padl1 padr1 bl">4</td> +<td rowspan="2" class="right padr0">-</td> +<td rowspan="2" class="bt bb bl"> </td> +<td rowspan="2" class="br"> </td> +<td class="center padl1 padr1 br">5</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">5</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br">.18</td> +<td class="right padl1 padr0">8</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +</tr> + +<tr> +<td class="center padl1 padr1 br">Mould</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>8</sub></td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br">.</td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr class="thinrow bb"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +</table> + +<p>These experiments, Mr. Walker informs us, +were made in the following manner:—</p> + +<p>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,<span class="pagenum"><a name="Page_30" id="Page_30">[30]</a></span> +and the loss of weight of each candle is contained +in the fourth column.</p> + +<p>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.</p> + +<p>The method which Mr. Walker employed +in comparing one light with another in each +experiment, was that which has been described +<a href="#Page_24">page 24</a>.</p> + +<p>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.</p> + +<p>2. The sign + in the 5th column, signifies<span class="pagenum"><a name="Page_31" id="Page_31">[31]</a></span> +that the candle against which it is placed, gave +a stronger light than the others.</p> + +<p>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.</p> + +<p>For if their quantities of matter be equal, +and times of burning the same, they will give +equal quantities of light, <em class="italic">by the experiments</em>.</p> + +<p>And if the times of burning be equal, the +quantities of light will be directly as their +weights of matter expended.</p> + +<p>Therefore the light is universally in the +compound ratio of the time of burning and +weight of matter consumed.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_32" id="Page_32">[32]</a></span> +of light produced under these circumstances, +be represented by 1.00.</p> + +<p>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.<a name="FNanchor_6" id="FNanchor_6"></a><a href="#Footnote_6" class="fnanchor">[6]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_6" id="Footnote_6"></a><a href="#FNanchor_6"><span class="label">[6]</span></a> To investigate rules for this purpose, 1. Let M represent +the mould candle, <i>a</i> its distance from the wall, on +which the shadows were compared, <i>x</i> its quantity of matter +consumed in a given time, (<i>t</i>) and Q the quantity of light +emitted by M in the same time: 2. Let <i>m</i> represent any +other candle, <i>b</i> its distance from the same wall, and <i>y</i> its +quantity of matter consumed, in the time <i>t</i>.</p> + +<p>Then as the intensities of light are directly as the squares +of the distances of the two candles from the wall, we have as +<i>a</i><sup>2</sup> : Q <span class="symbol">∷</span><span class="symbol_e">::</span> <i>b</i><sup>2</sup> : +<span class="division"><span class="num"><i>b</i><sup class="division">2</sup> + Q</span><span class="denom"><i>a</i><sup class="division">2</sup></span></span> = the quantity of light, emitted by +<i>m</i> in the time.</p> + +<p>Then let us suppose that the quantities of light are directly +as the quantities of matter consumed in the time <i>t</i>, and we +have, As <i>x</i> : Q <span class="symbol">∷</span><span class="symbol_e">::</span> <i>y</i> : <span class="division"><span class="num"><i>y</i> + Q</span><span class="denom"><i>x</i></span></span> = the quantity of light emitted +by <i>m</i> in that time, by hypothesis.</p> + +<p>Now, when <span class="division"><span class="num"><i>b</i><sup class="division">2</sup> + Q</span><span class="denom"><i>a</i><sup class="division">2</sup></span></span> (Theo. 1.) is = <span class="division"><span class="num">Y + Q</span><span class="denom">X</span></span> (Theo. 2.) the +quantities of light of M and <i>m</i> are directly as their quantities +of matter consumed in any given time.</p> + +</div> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_33" id="Page_33">[33]</a></span></p> + +<h4>METHOD<br /> +<span class="fsize60">OF INCREASING</span><br /> +THE LIGHT OF TALLOW CANDLES,<br /> +<span class="fsize60">AND TO OBVIATE THE</span><br /> +NECESSITY OF SNUFFING THEM.</h4> + +<p>Mr. <span class="smcap">Ezekiel Walker</span> 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.</p> + +<p>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<a name="FNanchor_7" id="FNanchor_7"></a><a href="#Footnote_7" class="fnanchor">[7]</a> 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:</p> + +<div class="footnote"> + +<p><a name="Footnote_7" id="Footnote_7"></a><a href="#FNanchor_7"><span class="label">[7]</span></a> 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.</p></div> + +<p><span class="pagenum"><a name="Page_34" id="Page_34">[34]</a></span></p> + +<p>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<a name="FNanchor_8" id="FNanchor_8"></a><a href="#Footnote_8" class="fnanchor">[8]</a>.</p> + +<div class="footnote"> + +<p><a name="Footnote_8" id="Footnote_8"></a><a href="#FNanchor_8"><span class="label">[8]</span></a> The wick’s not being uniformly twisted throughout, +may occasion a little variation in the dimensions of the +flame.</p></div> + +<p>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<span class="pagenum"><a name="Page_35" id="Page_35">[35]</a></span> +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.</p> + +<p>Candles, on which Mr. <span class="smcap">Walker</span> has made +experiments, are described in the following</p> + +<p class="center">TABLE.</p> + +<table class="nowrap" summary="Table page 35"> + +<tr class="bt bb"> +<th class="center padl1 padr1 bl br">No.</th> +<th class="center padl1 padr1 br">No. of<br />candles<br />to the<br />pound<br />avoir-<br />dupoise<br />weight.</th> +<th colspan="2" class="center padl1 padr1 br">Length<br />in<br />inches.</th> +<th class="center padl1 padr1 br">No. of<br />single<br />threads<br />of fine<br />cotton<br />in the wick.</th> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">1</td> +<td class="right padl1 padr3 br">14</td> +<td class="right padl1 padr0">8.</td> +<td class="left padl0 padr1 br">5</td> +<td class="center padl1 padr1 br">10</td> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">2</td> +<td class="right padl1 padr3 br">13</td> +<td class="right padl1 padr0">9.</td> +<td class="br"> </td> +<td class="center padl1 padr1 br">12</td> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">3</td> +<td class="right padl1 padr3 br">10</td> +<td class="right padl1 padr0">9.</td> +<td class="left padl0 padr1 br">74</td> +<td class="center padl1 padr1 br">14</td> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">4</td> +<td class="right padl1 padr3 br">8</td> +<td class="right padl1 padr0">10.</td> +<td class="br"> </td> +<td class="center padl1 padr1 br">20</td> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">5</td> +<td class="right padl1 padr3 br">6</td> +<td class="right padl1 padr0">10.</td> +<td class="left padl0 padr1 br">25</td> +<td class="center padl1 padr1 br">24</td> +</tr> + +<tr class="bb"> +<td class="center padl1 padr1 bl br">Mould</td> +<td class="right padl1 padr3 br">6</td> +<td class="right padl1 padr0">13.</td> +<td class="br"> </td> +<td class="br"> </td> +</tr> + +</table> + +<p>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.</p> + +<p>No. 4, placed at the angle mentioned above, +and lighted, requires no snuffing: it gives a<span class="pagenum"><a name="Page_36" id="Page_36">[36]</a></span> +light very little stronger than No. 1, but its +colour is not quite so white, nor its flame so +steady.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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,<span class="pagenum"><a name="Page_37" id="Page_37">[37]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_38" id="Page_38">[38]</a></span> +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.</p> + +<p>Mr. <span class="smcap">Walker</span> 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.</p> + +<p>The following observations on this subject +are copied from the Monthly Magazine, 1805, +p. 206.</p> + +<p>“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.</p> + +<p><span class="pagenum"><a name="Page_39" id="Page_39">[39]</a></span></p> + +<p>“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.</p> + +<p>“But I found an obstacle to the adoption of +Mr. <span class="smcap">Walker</span>’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.</p> + +<p>“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<span class="pagenum"><a name="Page_40" id="Page_40">[40]</a></span> +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.</p> + +<p>“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<span class="pagenum"><a name="Page_41" id="Page_41">[41]</a></span> +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.</p> + +<p>“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.”</p> + +<p>Lord <span class="smcap">Stanhope</span><a name="FNanchor_9" id="FNanchor_9"></a><a href="#Footnote_9" class="fnanchor">[9]</a> 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<span class="pagenum"><a name="Page_42" id="Page_42">[42]</a></span> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_9" id="Footnote_9"></a><a href="#FNanchor_9"><span class="label">[9]</span></a> Repository of Arts, Vol. I, p. 86.</p></div> + +<p>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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_43" id="Page_43">[43]</a></span></p> + +<p>A taper lamp, with eight threads of cotton, +will consume in one hour <sup>225</sup>⁄<sub>1000</sub> oz. of spermaceti +oil: at six shillings per gallon, the expence of +burning twelve hours is 13.71 farthings.</p> + +<p>At seven shillings, it is 15.995 farthings.</p> + +<p>At eight shillings, it is 18.280 farthings.</p> + +<p>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.</p> + +<p>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.</p> + +<p>At eight shillings, it is 8.022 farthings.</p> + +<p>At nine shillings, it is 9.024 farthings.</p> + +<p><span class="pagenum"><a name="Page_44" id="Page_44">[44]</a></span></p> + +<p class="center">TABLE,</p> + +<p class="center">Exhibiting a series of experiments, made with +a view to determine the real and comparative +expence of burning candles of different +sorts and sizes.</p> + +<table class="nowrap esmaller" summary="Table page 44"> + +<tr class="bt"> +<th class="bl br"> </th> +<th colspan="2" class="center padl1 padr1 br bb">Number of<br />candles<br />in one<br />pound.</th> +<th colspan="3" class="center padl1 padr1 br bb">Weight<br />of one<br />candle.</th> +<th colspan="2" class="center padl1 padr1 br bb">Time<br />one<br />candle<br />lasted.</th> +<th colspan="2" class="center padl1 padr1 br bb">The time<br />that<br />one pound<br />will last.</th> +<th colspan="2" class="center padl1 padr1 br bb">The expence in twelve hours<br />when candles are at 12s.<br />per dozen, which also shews<br />the proportion of expence<br />at any price, per dozen.</th> +</tr> + +<tr> +<th class="bl br"> </th> +<th colspan="2" class="br"> </th> +<th class="center padl1 padr1">Oz.</th> +<th colspan="2" class="center padl1 padr1 br">Dr.</th> +<th class="center padl1 padr1">Hr.</th> +<th class="center padl1 padr1 br">Min.</th> +<th class="center padl1 padr1">Hr.</th> +<th class="center padl1 padr1 br">Min.</th> +<th colspan="2" class="center padl1 padr1 br">Farthings and<br />hundredth parts.</th> +</tr> + +<tr> +<td rowspan="4" class="left padl1 padr1 bl br">A small<br />wick.<br />A large<br />wick.</td> +<td class="right padl1 padr0 bl">18</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">14</td> +<td class="br"> </td> +<td class="right padl1 padr1">3</td> +<td class="right padl1 padr2 br">15</td> +<td class="right padl1 padr1">59</td> +<td class="right padl1 padr2 br">26</td> +<td class="right padl1 padr0">9</td> +<td class="left padl0 padr1 br">.70</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">19</td> +<td class="br"> </td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">13</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">2</td> +<td class="right padl1 padr2 br">40</td> +<td class="right padl1 padr1">50</td> +<td class="right padl1 padr2 br">34</td> +<td class="right padl1 padr0">11</td> +<td class="left padl0 padr1 br">.40</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">16</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">2</td> +<td class="right padl1 padr2 br">40</td> +<td class="right padl1 padr1">44</td> +<td class="right padl1 padr2 br">2</td> +<td class="right padl1 padr0">13</td> +<td class="left padl0 padr1 br">.08</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">12</td> +<td class="br"> </td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">5</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr1">3</td> +<td class="right padl1 padr2 br">27</td> +<td class="right padl1 padr1">41</td> +<td class="right padl1 padr2 br">24</td> +<td class="right padl1 padr0">13</td> +<td class="left padl0 padr1 br">.92</td> +</tr> + +<tr> +<td rowspan="6" class="bl br"> </td> +<td class="right padl1 padr0 bl">10</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +<td class="right padl1 padr1">3</td> +<td class="right padl1 padr2 br">36</td> +<td class="right padl1 padr1">38</td> +<td class="right padl1 padr2 br">24</td> +<td class="right padl1 padr0">15</td> +<td class="left padl0 padr1 br">.00</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">7</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr1">4</td> +<td class="right padl1 padr2 br">9</td> +<td class="right padl1 padr1">32</td> +<td class="right padl1 padr2 br">12</td> +<td class="right padl1 padr0">17</td> +<td class="left padl0 padr1 br">.88</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">8</td> +<td class="br"> </td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr0">0</td> +<td class="br"> </td> +<td class="right padl1 padr1">4</td> +<td class="right padl1 padr2 br">15</td> +<td class="right padl1 padr1">34</td> +<td class="right padl1 padr2 br">0</td> +<td class="right padl1 padr0">16</td> +<td class="left padl0 padr1 br">.94</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">5</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr0">13</td> +<td class="br"> </td> +<td class="right padl1 padr1">5</td> +<td class="right padl1 padr2 br">19</td> +<td class="right padl1 padr1">30</td> +<td class="right padl1 padr2 br">15</td> +<td class="right padl1 padr0">19</td> +<td class="left padl0 padr1 br">.06</td> +</tr> + +<tr> +<td rowspan="2" colspan="2" class="center padl1 padr1 br">Mould<br />candles.</td> +<td colspan="3" class="br"> </td> +<td rowspan="2" colspan="2" class="br"> </td> +<td rowspan="2" colspan="2" class="br"> </td> +<td rowspan="2" colspan="2" class="center padl1 padr1 br">Moulds at 14d.<br />per dozen.</td> +</tr> + +<tr> +<td colspan="3" class="center padl1 padr1 br">Each.</td> +</tr> + +<tr> +<td rowspan="3" class="left padl1 padr1 bl br">With<br />wax’d<br />wick.</td> +<td class="right padl1 padr0 bl">3</td> +<td class="left padl0 padr1 br"><sup>7</sup>⁄<sub>8</sub></td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr0">12</td> +<td class="br"> </td> +<td class="right padl1 padr1">7</td> +<td class="right padl1 padr2 br">20</td> +<td class="right padl1 padr1">42</td> +<td class="right padl1 padr2 br">39</td> +<td class="right padl1 padr0">15</td> +<td class="left padl0 padr1 br">.74</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">4</td> +<td class="br"> </td> +<td class="center padl1 padr1">4</td> +<td class="right padl1 padr0">0</td> +<td class="br"> </td> +<td class="right padl1 padr1">9</td> +<td class="right padl1 padr2 br">3</td> +<td class="right padl1 padr1">36</td> +<td class="right padl1 padr2 br">20</td> +<td class="right padl1 padr0">18</td> +<td class="left padl0 padr1 br">.56</td> +</tr> + +<tr class="bb"> +<td class="right padl1 padr0 bl">3</td> +<td class="br"> </td> +<td class="center padl1 padr1">5</td> +<td class="right padl1 padr0">2</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr1">17</td> +<td class="right padl1 padr2 br">30</td> +<td class="right padl1 padr1">52</td> +<td class="right padl1 padr2 br">30</td> +<td class="right padl1 padr0">16</td> +<td class="left padl0 padr1 br">.825</td> +</tr> + +</table> + +<p>The time each candle lasted, was taken from +an average of several trials on each size.</p> + +<p>It has been suggested by Dr. <span class="smcap">Franklin</span>, that +the flame of two candles joined, gives a much +stronger light than both of them separately. +The same, has been observed by Mr. <span class="smcap">Warren</span>, +to be the case with flames of gas-lights, which,<span class="pagenum"><a name="Page_45" id="Page_45">[45]</a></span> +when combined, give a much stronger light +than they would afford, when in a separate +state.</p> + +<p>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.</p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_46" id="Page_46">[46-<br />47]</a><br /><a name="Page_47" id="Page_47"></a></span></p> + +<h2>PART II.</h2> + +<hr class="sect" /> + +<h3>GAS-LIGHT.</h3> + +<hr class="sect" /> + +<h4>PRELIMINARY OBSERVATION.</h4> + +<p>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 <em class="italic">gas-light</em>.</p> + +<p>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 “<em class="italic">Gas Light and Coke Company</em>,” +to apply this new art of procuring light, by<span class="pagenum"><a name="Page_48" id="Page_48">[48]</a></span> +way of experiment, on a large scale, in lighting +the streets of the metropolis.<a name="FNanchor_10" id="FNanchor_10"></a><a href="#Footnote_10" class="fnanchor">[10]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_10" id="Footnote_10"></a><a href="#FNanchor_10"><span class="label">[10]</span></a> 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.</p></div> + +<p>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<i>l.</i> and His Majesty has the power +of declaring the gas-light charter void, if the +company fail to fulfil the terms of it.</p> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_49" id="Page_49">[49]</a></span></p> + +<h3>THEORY<br /> +<span class="fsize60">OF</span><br /> +THE COMBUSTION OF COAL<br /> +<span class="fsize60">IN<br /> +ELUCIDATION OF THE NATURE AND PRODUCTION<br /> +OF</span><br /> +GAS LIGHT.</h3> + +<p>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<span class="pagenum"><a name="Page_50" id="Page_50">[50]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_51" id="Page_51">[51]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_52" id="Page_52">[52]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_53" id="Page_53">[53]</a></span> +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 <a href="#Page_15">page 15</a>.</p> + +<p>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 <a href="#Page_15">p. 15</a>. 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<span class="pagenum"><a name="Page_54" id="Page_54">[54]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_55" id="Page_55">[55]</a></span> +shape, at an expence out of all proportion below +the value of the products.</p> + +<hr class="sect" /> + +<h3>SKETCH<br /> +<span class="fsize60">OF</span><br /> +THE RISE AND PROGRESS<br /> +<span class="fsize60">OF THE</span><br /> +DISCOVERY AND APPLICATION<br /> +<span class="fsize60">OF</span><br /> +COAL-GAS,<br /> +<span class="fsize60">AS A SUBSTITUTE FOR PROCURING</span><br /> +ARTIFICIAL LIGHT.</h3> + +<p>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.</p> + +<p>In the Philosophical Transactions of the<span class="pagenum"><a name="Page_56" id="Page_56">[56]</a></span> +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.</p> + +<p>It is further known, that in the beginning of +the last century, Dr. Hales<a name="FNanchor_11" id="FNanchor_11"></a><a href="#Footnote_11" class="fnanchor">[11]</a> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_11" id="Footnote_11"></a><a href="#FNanchor_11"><span class="label">[11]</span></a> Vegetab. Statics, vol. I.</p></div> + +<p>In the year 1767, the Bishop of Llandaff<a name="FNanchor_12" id="FNanchor_12"></a><a href="#Footnote_12" class="fnanchor">[12]</a> +examined the nature of the vapour and gazeous +products evolved during the distillation of pit-coal. +This learned philosopher noticed, that<span class="pagenum"><a name="Page_57" id="Page_57">[57]</a></span> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_12" id="Footnote_12"></a><a href="#FNanchor_12"><span class="label">[12]</span></a> Watson’s Chemical Essays, vol. II.</p></div> + +<p>The first discovery and application of the +use of coal-gas for the purpose of illumination is +claimed by Mr. Murdoch.</p> + +<p>Dr. W. Henry of Manchester, has published +the following account<a name="FNanchor_13" id="FNanchor_13"></a><a href="#Footnote_13" class="fnanchor">[13]</a> of this discovery.</p> + +<div class="footnote"> + +<p><a name="Footnote_13" id="Footnote_13"></a><a href="#FNanchor_13"><span class="label">[13]</span></a> Thompson’s System of Chemistry, vol. I. p. 52.</p></div> + +<p>“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<span class="pagenum"><a name="Page_58" id="Page_58">[58]</a></span> +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.</p> + +<p><span class="pagenum"><a name="Page_59" id="Page_59">[59]</a></span></p> + +<p>“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.”</p> + +<p>In the year 1803 and 1804, Mr. Winsor +exhibited at the Lyceum in London the general<span class="pagenum"><a name="Page_60" id="Page_60">[60]</a></span> +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.</p> + +<p>Mr. <span class="smcap">Winsor</span>’s display of gas-lights took +place more than two years before Mr. <span class="smcap">Murdoch</span>’s +priority of right was heard of.</p> + +<p>In stating these facts I do not mean to say +that Mr. <span class="smcap">Murdoch</span> derived the hint of applying +the coal-gas from the previous exhibition +of Mr. <span class="smcap">Winsor</span>, because it is quite within +the bounds of probability that the ideas of Mr.<span class="pagenum"><a name="Page_61" id="Page_61">[61]</a></span> +<span class="smcap">Murdoch</span> may have arisen totally independent +of all acquaintance with Mr. <span class="smcap">Winsor</span>’s.</p> + +<p>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. <span class="smcap">Winsor</span> 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.<span class="pagenum"><a name="Page_62" id="Page_62">[62]</a></span> +<span class="smcap">Winsor</span>’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.</p> + +<p>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.</p> + +<p>On the 18th of May, 1804, Mr. <span class="smcap">Frederick +Albert Winsor</span>, 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.</p> + +<p>In the year 1805, Mr. <span class="smcap">Northern</span>, of Leeds,<span class="pagenum"><a name="Page_63" id="Page_63">[63]</a></span> +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.</p> + +<p>“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.</p> + +<p>“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<span class="pagenum"><a name="Page_64" id="Page_64">[64]</a></span> +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.</p> + +<p>“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.”</p> + +<p>Soon afterwards, Mr. <span class="smcap">Samuel Clegg</span><a name="FNanchor_14" id="FNanchor_14"></a><a href="#Footnote_14" class="fnanchor">[14]</a> of +Manchester, Engineer, communicated an account +of his method of lighting up manufactories<span class="pagenum"><a name="Page_65" id="Page_65">[65]</a></span> +with gas-light to the Society of Arts, +for which he received the silver medal.</p> + +<div class="footnote"> + +<p><a name="Footnote_14" id="Footnote_14"></a><a href="#FNanchor_14"><span class="label">[14]</span></a> This gentleman is at present engineer to the Gas-Light +Company.</p></div> + +<p>Since that time, the application of gas-light +has spread rapidly, and numerous manufactories +and other establishments have been +lighted by coal-gas.</p> + +<p>In France, the application of gas-lights to +economical purposes, was pointed out long +before it was publicly introduced into this +country. M. <span class="smcap">Le Bon</span> 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 <em class="italic">brevet +d’invention</em> (patent) granted to him by the +French government, for the art of producing +light from wood, ignited in close vessels.</p> + +<p>Many other attempts have been made to +derive advantage from the different ingredients +of coal; but they are too obscure to +merit particular enumeration.</p> + +<p>In the year 1808, Mr. <span class="smcap">Murdoch</span> presented +to the Royal Society his account of the application +of gas-light, and was complimented +with Count <span class="smcap">Romford</span>’s medal for the same.</p> + +<p><span class="pagenum"><a name="Page_66" id="Page_66">[66]</a></span></p> + +<p>The following statement is taken from Mr. +<span class="smcap">Murdoch</span>’s paper.</p> + +<p>“The whole of the rooms of the cotton mill +of Mr. <span class="smcap">Lee</span>, 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. <span class="smcap">Lee</span>, +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, (<em class="italic">see <a href="#Page_23">page 23</a></em>) 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.</p> + +<p>“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.</p> + +<p><span class="pagenum"><a name="Page_67" id="Page_67">[67]</a></span></p> + +<p>“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.</p> + +<p>“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<span class="pagenum"><a name="Page_68" id="Page_68">[68]</a></span> +cannel-coal is required in the retort. The price +of the best Wiggan cannel-coal (the sort used) +is 13<sup>1</sup>⁄<sub>2</sub><i>d.</i> per cwt. (22<i>s.</i> 6<i>d.</i> 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<i>l.</i></p> + +<p>“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<i>l.</i></p> + +<p>“The 110 tons of cannel-coal, when distilled, +produce about 70 tons of good coke, which is +sold upon the spot at 1<i>s.</i> 4<i>d.</i> per cwt. and will +therefore amount annually to the sum of 93<i>l.</i></p> + +<p>“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.</p> + +<p>“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. <span class="smcap">Lee</span> at about +550<i>l.</i> per annum, in which some allowance is<span class="pagenum"><a name="Page_69" id="Page_69">[69]</a></span> +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.</p> + +<p>“Mr. <span class="smcap">Lee</span> 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.</p> + +<p>“The economical statement for one year, +then, stands thus:</p> + +<table summary="Table page 69"> + +<tr> +<td class="left top padr3">Cost of 110 tons of cannel coal</td> +<td class="right bot">£ 125</td> +</tr> + +<tr> +<td class="left top padr3">Ditto of 40 tons of common ditto, to carbonise</td> +<td class="right bot bb">20</td> +</tr> + +<tr> +<td class="left top padr3">In all</td> +<td class="right bot bb">145</td> +</tr> + +<tr> +<td class="left top padr3">Deduct the value of 70 tons of coke</td> +<td class="right bot">93</td> +</tr> + +<tr> +<td class="left top padr3">The annual expenditure in coal, after deducting the value of the coke, and without allowing any thing for the tar, is therefore</td> +<td class="right bot">52</td> +</tr> + +<tr> +<td class="left top padr3">And the interest of capital sunk, and wear and tear of apparatus</td> +<td class="right bot">550</td> +</tr> + +<tr> +<td class="left top padr3">Making the total expence of the gas apparatus per annum, about</td> +<td class="right bot">600</td> +</tr> + +</table> + +<p>“That of candles, to give the same light,<span class="pagenum"><a name="Page_70" id="Page_70">[70]</a></span> +would be about 2000<i>l.</i> 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.</p> + +<p>“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<i>l.</i> while that of the tallow would be +3000<i>l.</i>”</p> + +<p>Mr. <span class="smcap">Ackerman</span> 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. <span class="smcap">Ackerman</span>’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:</p> + +<p><span class="pagenum"><a name="Page_71" id="Page_71">[71]</a></span></p> + +<blockquote> + +<p class="center">To <span class="smcap">Mr.</span> ACCUM.</p> + +<p><span class="smcap">Sir</span>,</p> + +<p>“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.</p> + +<p>Now 365 retorts containing 120lb. of coal each, make 43800lb. +which is equal to ten chaldrons of Newcastle and eight tons of +cannel coal.</p> + +<table summary="Table page 71"> + +<tr> +<td class="right top padr1" style="width: 1em;">10</td> +<td colspan="3" class="left top padr3">chaldrons of Newcastle coals, at 65s. make</td> +<td class="right bot padl1 padr1">£ 32</td> +<td class="right bot padl1 padr1">10</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="right top padr1">8</td> +<td colspan="3" class="left top padr3">tons of cannel coal,<a name="FNanchor_15" id="FNanchor_15"></a><a href="#Footnote_15" class="fnanchor">[15]</a> (this coal is sold by weight) at 100s. per ton</td> +<td class="right bot padl1 padr1">40</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="right top padr1">7</td> +<td colspan="3" class="left top padr3">chaldrons of common coals for carbonising, at 55s.</td> +<td class="right bot padl1 padr1">19</td> +<td class="right bot padl1 padr1">5</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="4" class="left top padr3">To wages paid the servant for attending the gas apparatus</td> +<td class="right bot padl1 padr1">30</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="4" class="left top padr3">Interest of money sunk</td> +<td class="right bot padl1 padr1">30</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td> </td> +<td colspan="3" class="left top padr3">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.</td> +<td colspan="3" class="bb"> </td> +</tr> + +<tr> +<td colspan="4" class="right top padr3">Total expence of the gas lights</td> +<td class="right bot padl1 padr1">151</td> +<td class="right bot padl1 padr1">15</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="7" class="center top blankabove blankbelow">DEDUCT</td> +</tr> + +<tr> +<td class="right top padr1">23</td> +<td class="left top padr3">chaldrons of coke, at 60s. per chaldron</td> +<td class="right bot padl1 padr1">69</td> +<td colspan="4"> </td> +</tr> + +<tr> +<td colspan="2" class="left top padr3">Ammoniacal liquor</td> +<td class="right bot padl1 padr1">5</td> +<td colspan="4"> </td> +</tr> + +<tr> +<td colspan="2" class="left top padr3">Tar</td> +<td class="right bot padl1 padr1">6</td> +<td colspan="4"> </td> +</tr> + +<tr> +<td colspan="2" class="left top padr3">Charcoal employed by the copper-plate printers to heat their plates, which is now done with the gas-light flame, cost, annually</td> +<td class="right bot padl1 padr1">25</td> +<td colspan="4"> </td> +</tr> + +<tr> +<td colspan="2" class="left top padr3">Two chaldrons of coals <em class="italic">minus</em> used as fuel, for warming the house, since the adoption of the gas-lights, at 65s. per chaldron</td> +<td class="right bot padl1 padr1 bb">6</td> +<td class="right bot padl1 padr1 bb">10</td> +<td colspan="3"> </td> +</tr> + +<tr> +<td colspan="4"> </td> +<td class="right bot padl1 padr1 bb">111</td> +<td class="right bot padl1 padr1 bb">10</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td colspan="4" class="right top padr3">Nett expences of the gas-lights</td> +<td class="right bot padl1 padr1 bb">£ 40</td> +<td class="right bot padl1 padr1 bb">5</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td colspan="4" class="left top padr3">The lights used in my Establishment, prior to the gas-lights, amounted annually to</td> +<td class="right bot padl1 padr1">160</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="4" class="left top padr3">My present system of lighting with gas costs, per ann.</td> +<td class="right bot padl1 padr1 bb">40</td> +<td class="right bot padl1 padr1 bb">5</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td colspan="4" class="right top padr3">Balance in favor of the gas for one year</td> +<td class="right bot padl1 padr1">£ 119</td> +<td class="right bot padl1 padr1">15</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +</table> + +</blockquote> + +<div class="footnote"> + +<p><a name="Footnote_15" id="Footnote_15"></a><a href="#FNanchor_15"><span class="label">[15]</span></a> <em class="italic">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.</em></p></div> + +<p><span class="pagenum"><a name="Page_72" id="Page_72">[72]</a></span></p> + +<blockquote> + +<p>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.</p> + +<p class="center">I am, with respect,<br /> +Yours,</p> + +<p class="placedate">Strand, March 13,<br /> +1815.</p> + +<p class="signature">R. ACKERMAN.”</p> + +</blockquote> + +<p>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. +<span class="smcap">Cook</span>, 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 <em class="italic">naïveté</em> in his own +account of the process which will amuse as well +as instruct the reader.</p> + +<p>“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<span class="pagenum"><a name="Page_73" id="Page_73">[73]</a></span> +make perhaps six hundred gallons<a name="FNanchor_16" id="FNanchor_16"></a><a href="#Footnote_16" class="fnanchor">[16]</a> 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.”</p> + +<div class="footnote"> + +<p><a name="Footnote_16" id="Footnote_16"></a><a href="#FNanchor_16"><span class="label">[16]</span></a> A wine-gallon is equal to 231 cubic inches.</p></div> + +<p>Thus are the candles which Mr. <span class="smcap">Cook</span> 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<i>l.</i> 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<span class="pagenum"><a name="Page_74" id="Page_74">[74]</a></span> +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. <span class="smcap">Cook</span>’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<i>l.</i> out of the 50<i>l.</i> 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. <span class="smcap">Cook</span> assures us, “will still be considerable:<span class="pagenum"><a name="Page_75" id="Page_75">[75]</a></span> +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<i>l.</i> or 12<i>l.</i> which he will nearly, if not +quite, save the first year.”</p> + +<p>Mr. <span class="smcap">Ackerman</span> 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. +<span class="smcap">Lloyd</span>, of Queen Street, Southwark, thimble +manufacturers and whitesmiths, who have used +the gas-light for soldering and other purposes +these five years past.</p> + +<table summary="Table page 75-76"> + +<tr> +<td class="left top padr3">From 4 pecks or 1 bushel of coals, weighing 69lbs. for which we now pay (1809) 1s. we produce 4<sup>3</sup>⁄<sub>4</sub> pecks of coke and <sup>1</sup>⁄<sub>2</sub> peck of coal not carbonised remains in the distilling pot, which together with the coke weighs 58lbs. 6 oz. value at 1s. per bushel</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">1</td> +<td class="right bot padl1 padr1">4</td> +</tr> + +<tr> +<td class="left top padr3">we procure 6lbs. 4 oz. of tar which<span class="pagenum"><a name="Page_76" id="Page_76">[76]</a></span> we use as pith—it saves us</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">1</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td> </td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">2</td> +<td class="right bot padl1 padr1">4</td> +</tr> + +<tr> +<td class="center top">Deduct for coal</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">1</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td class="left top padr3">Profit on coke and tar</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">1</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td class="left top padr3">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</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">7</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">To this, add profits on coke and tar</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">1</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td class="left top padr3">Gained out of every bushel of coal</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">8</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +</table> + +<p>“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.”</p> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_77" id="Page_77">[77]</a></span></p> + +<h3>THEORY<br /> +<span class="fsize60">OF</span><br /> +THE PRODUCTION OF GAS-LIGHT,<br /> +<span class="fsize60">AND</span><br /> +DESCRIPTION<br /> +<span class="fsize60">OF</span><br /> +A PORTABLE APPARATUS<br /> +<span class="fsize60">FOR EXHIBITING, IN THE SMALL WAY, THE GENERAL<br /> +NATURE OF THIS SPECIES OF LIGHT.</span></h3> + +<p>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<span class="pagenum"><a name="Page_78" id="Page_78">[78]</a></span> +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<span class="pagenum"><a name="Page_79" id="Page_79">[79]</a></span> +which the gas alone can issue, thus forming +small distinct streams of light.</p> + +<div class="figcenter"><a name="Plate2" id="Plate2"></a> +<img src="images/illo093.jpg" alt="Gas-apparatus" width="600" height="383" /> +<p class="largeimg"><a href="images/lg093.jpg">Larger image</a> (279 kB)</p> +</div> + +<p>The gas-apparatus, <a href="#Plate2">plate 2</a>, 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.</p> + +<p>It consists of three distinct apparatus:—namely, +a portable furnace, <a href="#Plate2">fig. 1, plate 2</a>, by +means of which the gas is prepared—<a href="#Plate2">fig. 2</a>, 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—<a href="#Plate2">fig. +3</a>, 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:—<i>a</i>, +represents a cast iron retort, such as +is used for chemical operations in the small<span class="pagenum"><a name="Page_80" id="Page_80">[80]</a></span> +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. <i>b.</i> is a metal pipe which conveys +all the distillatory products from the retort into +the purifier <a href="#Plate2">fig. 2</a>. This tube is bent at right +angles at the extremity where it enters the intermediate +vessel <a href="#Plate2">fig. 2</a>. The purifier <a href="#Plate2">fig. 2</a>, is +divided into three compartments marked <i>c.</i> <i>d.</i> <i>e.</i> +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, <i>d</i>, 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<span class="pagenum"><a name="Page_81" id="Page_81">[81]</a></span> +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 <i>e</i> is left empty +to receive the tar and other liquid products. +Into the first compartment <i>c</i>, all the gazeous +and liquid products are delivered, as they +become evolved during the distillation, by +means of the pipe <i>b</i>. The compartment <i>d</i>, 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 <i>b</i>, to pass readily +through it. From the chamber <i>c</i>, the liquid +and gazeous products pass to the tar-chamber, +or compartment <i>e</i>, by means of the descending +pipe <i>f</i>. The tar and other condensible substances +are therefore deposited at <i>e</i>, whilst the +gazeous products alone ascend from the tar-chamber +<i>e</i>, by the pipe <i>g</i>, and down again +the pipe <i>h</i>, (which is closed at the top) into +the compartment <i>d</i>, of the vessel or purifier, +<a href="#Plate2">fig. 2</a>. The gas being thus made to pass from +the compartment <i>e</i>, up into the pipe <i>g</i>, and +down the pipe <i>h</i>, (which is closed at the top) +into the purifier <i>d</i>, is brought into contact with<span class="pagenum"><a name="Page_82" id="Page_82">[82]</a></span> +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 <i>c</i>, 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>i</i> +is another wide-mouth funnel, by +means of which the chamber <i>d</i>, 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 <i>d</i>, of the +purifier, forming carbonate and hidro-sulphuret +of lime. The carburetted hidrogen, being +left more or less pure, is conveyed through the +pipe <i>k</i>, into the gasometer, <a href="#Plate2">fig. 3</a>. The communication +of the purifier, <a href="#Plate2">fig. 2</a>, with the gasometer, +is made by means of the well-known +water-valve <i>l</i>, placed so that the communicating +tube <i>k</i>, may be easily removed at pleasure—<i>m</i>, +is a cock for drawing off the tar, &c. +<i>n</i>, a gauge-cock for ascertaining the height of<span class="pagenum"><a name="Page_83" id="Page_83">[83]</a></span> +the liquid in the chamber <i>d</i>. The gasometer, +<a href="#Plate2">fig. 3</a>, 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. <i>o</i> is a +pipe, which communicates with the water-valve +<i>l</i>, and by means of which the gas passes +from the purifier, <a href="#Plate2">fig. 2</a>, into the gasometer. +The upper end of this pipe is covered, in the +manner of a hood, by a cylindrical vessel <i>p</i>, +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 <i>p</i>, 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<span class="pagenum"><a name="Page_84" id="Page_84">[84]</a></span> +the gasometer, which is suspended to move up +and down by the chains, pullies, and balance-weights, +<i>q</i>. From the centre of the gasometer +a tube, <i>r</i>, descends, which includes a pipe, <i>s</i>, +fixed perpendicular from the bottom of the +cistern. The fixed pipe <i>r</i>, forms a guide to +keep the gasometer always perpendicular. <i>t</i> is +also an iron pipe made fast in the centre of the +inner vessel, and communicates with the upright +tube, <i>s</i>, in the outer vessel. This contrivance +obliges the gas to pass into the pipe <i>t</i>, +whilst it also serves to keep the gasometer +steady when nearly out of the outer cistern.</p> + +<p>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 <i>q</i> <i>q</i>, 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 <i>o</i>, into +the vessel, <i>p</i>, from which it displaces the +water, and passes out at the small holes, as<span class="pagenum"><a name="Page_85" id="Page_85">[85]</a></span> +before described, rising through the water into +the gasometer, and raising it up: the gas then +passes away to the burners, <i>u</i> <i>u</i>. 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. <i>v</i> <i>v</i> are cocks to let off any +liquid that may collect in the pipe <i>o</i> or <i>t</i>; 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, <em class="italic">dance</em>, or become extinguished. +<i>x</i> is the main stop-cock which communicates +with the burners—these, of course, may be +placed as convenience may require. <i>z</i> <i>z</i> are +two projecting parts in the top of the gasometer;<span class="pagenum"><a name="Page_86" id="Page_86">[86]</a></span> +they are intended to receive the hood <i>p</i>, +and the upper extremity of the pipe <i>t</i>, 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.</p> + +<p>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<span class="pagenum"><a name="Page_87" id="Page_87">[87]</a></span> +of the size of the flames; which could +not be rendered uniform.</p> + +<p>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.</p> + +<p>To compensate for this increasing weight of +the gasometer, and render a scale of equal +graduations accurate, some have ingeniously<span class="pagenum"><a name="Page_88" id="Page_88">[88]</a></span> +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.</p> + +<p>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.</p> + +<p>Pit-coal is not the only substance which affords +carburetted hydrogen; this gazeous fluid<span class="pagenum"><a name="Page_89" id="Page_89">[89]</a></span> +may be obtained in a great variety of ways, +and with very considerable differences in specific +gravity and proportion of ingredients.</p> + +<p>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.</p> + +<p>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 <em class="italic">ignis fatuus</em> 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.</p> + +<p>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<span class="pagenum"><a name="Page_90" id="Page_90">[90]</a></span> +into the bottle; when by thus stirring the mud +in various places, the air may be catched in the +bottle.</p> + +<p>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.</p> + +<p>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 +(<span class="smcap">Van Dieman</span>, <span class="smcap">Troostwyck</span>, 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.<span class="pagenum"><a name="Page_91" id="Page_91">[91]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_92" id="Page_92">[92]</a></span> +air as 2 to 3—112lb. of common cannel coal produce +at its <em class="italic">minimum</em>, 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) <span class="division"><span class="num">7000</span><span class="denom">175</span></span> = 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,<span class="pagenum"><a name="Page_93" id="Page_93">[93]</a></span> +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 <em class="italic">minimum</em>, +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 <span class="division"><span class="num">350</span><span class="denom">20</span></span> = +17<sup>1</sup>⁄<sub>2</sub>lbs. 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.</p> + +<p>With regard to Newcastle coals<a name="FNanchor_17" id="FNanchor_17"></a><a href="#Footnote_17" class="fnanchor">[17]</a>, 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_17" id="Footnote_17"></a><a href="#FNanchor_17"><span class="label">[17]</span></a> One chaldron of Newcastle coal weighs from 2850 to +upwards of 2978lb.</p></div> + +<p>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<span class="pagenum"><a name="Page_94" id="Page_94">[94]</a></span> +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.<a name="FNanchor_18" id="FNanchor_18"></a><a href="#Footnote_18" class="fnanchor">[18]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_18" id="Footnote_18"></a><a href="#FNanchor_18"><span class="label">[18]</span></a> One pound of coal-tar produces 15 cubic feet of carburetted +hidrogen abounding in olifiant gas.</p></div> + +<p>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.</p> + +<p>The retorts best calculated for large gas-light +works are seven or eight foot long (without the +mouth-piece) and twelve inches in diameter,<span class="pagenum"><a name="Page_95" id="Page_95">[95]</a></span> +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;<a name="FNanchor_19" id="FNanchor_19"></a><a href="#Footnote_19" class="fnanchor">[19]</a> 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<span class="pagenum"><a name="Page_96" id="Page_96">[96]</a></span> +an intolerable suffocating odour, when the gas +is burnt which is particularly perceptible in low +rooms illuminated with such gas.</p> + +<div class="footnote"> + +<p><a name="Footnote_19" id="Footnote_19"></a><a href="#FNanchor_19"><span class="label">[19]</span></a> It is chiefly a mixture of carbonic oxid, and hydrogen gas.</p></div> + +<p>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.</p> + +<p>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.</p> + +<p>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. +<sup>1</sup>⁄<sub>27</sub> part of its own bulk of pure coal-gas<span class="pagenum"><a name="Page_97" id="Page_97">[97]</a></span> +is absorbed by the water over which it is confined +in the gazometer.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_98" id="Page_98">[98]</a></span> +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.</p> + +<p>“Messrs. <span class="smcap">Sobolewsky</span> and <span class="smcap">Horrer</span>, 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<span class="pagenum"><a name="Page_99" id="Page_99">[99]</a></span> +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.”<a name="FNanchor_20" id="FNanchor_20"></a><a href="#Footnote_20" class="fnanchor">[20]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_20" id="Footnote_20"></a><a href="#FNanchor_20"><span class="label">[20]</span></a> See Repository of Arts, Vol. XI. No. 36, p. 341.</p></div> + +<hr class="sect" /> + +<h3>UTILITY<br /> +<span class="fsize60">OF THE</span><br /> +GAS-LIGHT ILLUMINATION,<br /> +<span class="fsize60">WITH REGARD TO</span><br /> +PUBLIC AND PRIVATE ECONOMY.</h3> + +<p>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<span class="pagenum"><a name="Page_100" id="Page_100">[100]</a></span> +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<span class="pagenum"><a name="Page_101" id="Page_101">[101]</a></span> +in all our common lights. The products +of the combustion are water and carbonic acid +gas<a name="FNanchor_21" id="FNanchor_21"></a><a href="#Footnote_21" class="fnanchor">[21]</a>. The accurate and elegant experiments +of Dr. W. <span class="smcap">Henry</span> 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<a name="FNanchor_22" id="FNanchor_22"></a><a href="#Footnote_22" class="fnanchor">[22]</a>, which<span class="pagenum"><a name="Page_102" id="Page_102">[102]</a></span> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_21" id="Footnote_21"></a><a href="#FNanchor_21"><span class="label">[21]</span></a> 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.</p></div> + +<div class="footnote"> + +<p><a name="Footnote_22" id="Footnote_22"></a><a href="#FNanchor_22"><span class="label">[22]</span></a> 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. +</p> +<blockquote> + +<p>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. +</p> +<p> +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.” +</p> +<p> +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.” +</p> +<p> +Q. “And you say the same in regard to the use of the gas-lights +in your own family?—A. Certainly I do.”</p></blockquote> +</div> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_103" id="Page_103">[103]</a></span></p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_104" id="Page_104">[104]</a></span> +by the stand or support of the combustible +matter.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_105" id="Page_105">[105]</a></span> +house. When transparencies are wanted as +decorations for halls, lobbies, &c. more than +light, recesses may be filled with different coloured +<em class="italic">media</em>, or paintings, and any intensity of +light may be thrown on the object.</p> + +<p>If a number of minute holes are made in +the end of a gas pipe, it forms as many <i lang="fr" xml:lang="fr">jets +de feu</i>, 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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_106" id="Page_106">[106]</a></span> +night of a general illumination, compared with +the glimmering light of its ordinary parish +lamps.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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,<span class="pagenum"><a name="Page_107" id="Page_107">[107]</a></span> +no doubt will pay all its expences besides the +interest of capital, and leave a surplus of profit.</p> + +<p>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.<a name="FNanchor_23" id="FNanchor_23"></a><a href="#Footnote_23" class="fnanchor">[23]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_23" id="Footnote_23"></a><a href="#FNanchor_23"><span class="label">[23]</span></a> 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. +</p> +<p> +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. +</p> +<p> +In the East end of the metropolis, the gas-light <em class="italic">mains</em> 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.</p></div> + +<p>Enough therefore, has been done to prove the +possibility of lighting houses, and streets, with<span class="pagenum"><a name="Page_108" id="Page_108">[108]</a></span> +gas, which would have been regarded twenty +years ago as an extravagant paradox.<a name="FNanchor_24" id="FNanchor_24"></a><a href="#Footnote_24" class="fnanchor">[24]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_24" id="Footnote_24"></a><a href="#FNanchor_24"><span class="label">[24]</span></a> I am informed by Mr. <span class="smcap">Clegg</span>, 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. +</p> + +<blockquote> + +<p>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. +</p> +<p> +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.</p></blockquote> +</div> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_109" id="Page_109">[109]</a></span></p> + +<p>Another advantageous application of the gas-light +must be the supplying of light-houses.</p> + +<p>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.</p> + +<p>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.</p> + +<p>The ease with which the largest gas-light +flame is instantly extinguished by shutting the<span class="pagenum"><a name="Page_110" id="Page_110">[110]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_111" id="Page_111">[111]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p>The heat produced by gas-lights must be +observed by every one who has had an opportunity<span class="pagenum"><a name="Page_112" id="Page_112">[112]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>From trials made on this subject, I am enabled<span class="pagenum"><a name="Page_113" id="Page_113">[113]</a></span> +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.<a name="FNanchor_25" id="FNanchor_25"></a><a href="#Footnote_25" class="fnanchor">[25]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_25" id="Footnote_25"></a><a href="#FNanchor_25"><span class="label">[25]</span></a> Mr. <span class="smcap">Dalton</span>’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: +</p> +<p> +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. +</p> +<p> +It was thus proved that— +</p> + +<table summary="Table footnote 25"> + +<tr> +<td class="left top padr3">Olefiant gas raises an equal volume of water</td> +<td class="left bot">14°</td> +</tr> + +<tr> +<td class="left top padr3">Carburetted hidrogen, or coal gas</td> +<td class="left bot">10</td> +</tr> + +<tr> +<td class="left top padr3">Carbonic oxid</td> +<td class="left bot">4</td> +</tr> + +<tr> +<td class="left top padr3">Hidrogen</td> +<td class="left bot">5</td> +</tr> + +<tr> +<td class="left top padr3">Spermaceti oil 10 grains burnt in a lamp raised 30,000 grains of water</td> +<td class="left bot">5</td> +</tr> + +<tr> +<td class="left top padr3">Tallow</td> +<td class="left bot">5</td> +</tr> + +<tr> +<td class="left top padr3">Wax</td> +<td class="left bot">5,75</td> +</tr> + +<tr> +<td class="left top padr3">Oil of turpentine</td> +<td class="left bot">3</td> +</tr> + +<tr> +<td class="left top padr3">Spirit of wine</td> +<td class="left bot">2</td> +</tr> + +</table> + +</div> + +<p>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<span class="pagenum"><a name="Page_114" id="Page_114">[114]</a></span> +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.</p> + +<p>The great power of a gas-flame does not +appear when we try small quantities of it, and<span class="pagenum"><a name="Page_115" id="Page_115">[115]</a></span> +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.</p> + +<div class="figcenter"><a name="Plate3" id="Plate3"></a> +<img src="images/illo131.jpg" alt="Gas lamps" width="600" height="367" /> +<p class="largeimg"><a href="images/lg131.jpg">Larger image</a> (252 kB)</p> +</div> + +<p>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.</p> + +<p>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.</p> + +<p><a href="#Plate3"><span class="smcap">Plates</span> III.</a> <a href="#Plate4">IV.</a> and <a href="#Plate5">V.</a> exhibit such designs +of different kinds of gas-lamps, chandeliers, +lustres, candelabras, &c. as are already in use +in this Metropolis.</p> + +<p><a href="#Plate3"><span class="smcap">Plate</span> III. fig. 1</a>, represents a <em class="italic">Rod Lamp</em>. +The gas passes through the rod <i>a</i>, to the Argand +burner, which is surrounded by a cylindrical +chimney, <i>c</i>, swelling out at the lower<span class="pagenum"><a name="Page_116" id="Page_116">[116]</a></span> +extremity. The construction of the Argand +burner we have mentioned already, <a href="#Page_78"><i>p.</i> 78</a>.</p> + +<p>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.</p> + +<p><a href="#Plate3">Fig. 2</a>. <em class="italic">A Rod Gas Lamp, with branches.</em> +The gas passes through the hollow rod, <i>a</i>, and +part of the hollow branch, <i>b</i>, to the burner of +the lamp. The cylindrical shaped glass, <i>c</i>, exhibited +in this figure, is not so well adapted for +the compleat combustion of coal-gas, as the +belly-shaped chimney, <i>c</i>, represented in<span class="pagenum"><a name="Page_117" id="Page_117">[117]</a></span> <a href="#Plate3">fig. 1, +3, 5, 6</a>, 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, +<a href="#Plate3">fig. 1</a>.</p> + +<p><a href="#Plate3">Fig. 3</a>. <em class="italic">A Bracket Lamp.</em> <i>a</i>, the tube +which conveys the gas to the burner; <i>b</i>, the +stop-cock of the tube.</p> + +<p><a href="#Plate3">Fig. 4</a>. <em class="italic">A Pendent Rod Lamp</em>; in which the +gas is supposed to come from a pipe above, +through the ceiling, into the pipe, <i>a</i>, to supply +the burners. The tulip-shaped chimney, <i>b</i>, +of this lamp, is likewise ill adapted for gas-light +burners.</p> + +<p><a href="#Plate3">Fig. 5</a>. <em class="italic">A pendent double-bracket Lamp.</em> +The gas passing through the perpendicular +tube, <i>a</i>, into the brackets, <i>b</i> <i>b</i>; <i>c</i> shows the +Argand burner.</p> + +<p><span class="pagenum"><a name="Page_118" id="Page_118">[118]</a></span></p> + +<p><a href="#Plate3">Fig. 6</a>. <em class="italic">A swing Bracket Lamp.</em> <i>a</i>, the +gas-pipe with its stop-cock; <i>b</i>, a brass ball, +communicating with the pipe, <i>a</i>; <i>c</i>, the conducting +tube, ground air-tight into the ball, +<i>b</i>, and communicating with the burner of the +lamp, so as to allow it to have an horizontal +motion.</p> + +<p><a href="#Plate3">Fig. 7</a>. Shews the construction of the ball +<i>b</i>, and pipe, <i>c</i>, of the lamp, <a href="#Plate3">fig. 6</a>.</p> + +<p><a href="#Plate3">Fig. 8</a>. <em class="italic">A Swing Cockspur Lamp</em>, constructed +upon the same plan as <a href="#Plate3">fig. 6</a>. These two +lamps are very convenient for desks in counting-houses, +&c.</p> + +<p><a href="#Plate3">Fig. 9</a>. 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.</p> + +<p><a href="#Plate3">Fig. 10</a>. Section of the stop-cock, with ball +and socket.</p> + +<p><a href="#Plate3">Fig. 11</a>. Shows the ball and socket, <a href="#Plate3">fig. 9</a>, +in perspective.</p> + +<div class="figcenter"><a name="Plate4" id="Plate4"></a> +<img src="images/illo137.jpg" alt="Gas lamps" width="600" height="343" /> +<p class="largeimg"><a href="images/lg137.jpg">Larger image</a> (205 kB)</p> +</div> + +<p><a href="#Plate4"><span class="smcap">Plate</span> IV</a>,<a name="FNanchor_26" id="FNanchor_26"></a><a href="#Footnote_26" class="fnanchor">[26]</a> <a href="#Plate4">fig. 1</a>. <em class="italic">A Candelabrum</em>; the gas<span class="pagenum"><a name="Page_119" id="Page_119">[119]</a></span> +pipe ascending from the floor of the apartment, +through the column <i>a</i>, and terminating +in the burner of the lamp.</p> + +<div class="footnote"> + +<p><a name="Footnote_26" id="Footnote_26"></a><a href="#FNanchor_26"><span class="label">[26]</span></a> The gas-lamps exhibited in this plate, are employed +in the library, counting-house, warehouse, and offices of +Mr. <span class="smcap">Ackerman</span>, and, by whose permission, they are copied +on this occasion.</p></div> + +<p><a href="#Plate4">Fig. 2</a>. <em class="italic">A fancy pendent Cockspur Lamp.</em> +The gas being transmitted to the burners, <i>c</i> <i>c</i>, +by means of the pipe, <i>a</i>.</p> + +<p><a href="#Plate4">Fig. 3</a>. <em class="italic">A Pedestal Argand Lamp.</em> <i>a</i>, the +pipe and stop-cock, which transmits to, and +shuts off the gas from the burner of the lamp.</p> + +<p><a href="#Plate4">Fig. 4</a>. <em class="italic">A Pedestal Cockspur Lamp.</em> <i>a</i>, the +stop-cock and gas-pipe.</p> + +<p><a href="#Plate4">Fig. 5</a>. <em class="italic">A fancy bracket Cockspur Lamp</em>, +intended merely to show that the coal-gas, as +it passes to the burner, is perfectly devoid of +colour, and invisible. <i>a</i> is a glass vessel furnished +at its orifice with a brass cap, <i>c</i>, and +perforated ball, out of which the gas-flame +proceeds. <i>b</i>, the pipe which conveys the gas +into the glass vessel, <i>a</i>.</p> + +<p><a href="#Plate4">Fig. 6</a>. <em class="italic">A Bracket Argand Lamp.</em> <i>a</i> and <i>b</i>, +the gas pipe communicating with the burner.</p> + +<p><a href="#Plate4">Fig. 7 and 8</a>. <em class="italic">A Horizontal Bracket Lamp.</em> +<i>a</i>, the gas pipe, supposed to be concealed +in the ceiling. <i>b</i>, the communicating pipe, +which, together with <i>c</i>, branches out at right +angles at <i>d</i> <i>d</i>. <i>e</i> <i>e</i>, are the burners of the lamp.</p> + +<div class="figcenter"><a name="Plate5" id="Plate5"></a> +<img src="images/illo140.jpg" alt="Gas lamps" width="600" height="355" /> +<p class="largeimg"><a href="images/lg140.jpg">Larger image</a> (286 kB)</p> +</div> + +<p><span class="pagenum"><a name="Page_120" id="Page_120">[120]</a></span></p> + +<p><a href="#Plate5"><span class="smcap">Plate</span> V</a>. <a href="#Plate5">fig. 1</a>. <em class="italic">A Candelabrum</em>, into which +the gas-pipe ascends from the floor of the +apartment, the lateral branches communicating +with the central tube.</p> + +<p><a href="#Plate5">Fig. 2</a>. <em class="italic">An Arabesque Chandelier.</em> The gas +enters from the ceiling of the room into the +rope-shaped pipe, <i>a</i>, from which it proceeds +through one of the arched ribs, <i>b</i> <i>b</i>, into the +horizontal hoop, or pipe, <i>c</i>.</p> + +<p><a href="#Plate5">Fig. 3</a>. <em class="italic">A Roman Chandelier.</em> The gas enters +through the inflexible hollow chain, <i>a</i>, into +the central tube, <i>b</i>, from whence the burners +are supplied by the lateral branches, <i>c</i> <i>c</i>.</p> + +<p><a href="#Plate5">Fig. 4</a>. <em class="italic">A Gothic Chandelier.</em> The gas is +transmitted to the burners through the rope, <i>a</i>, +which includes a tube, and the communication +with the burners is established through the +lateral branches.</p> + +<p><a href="#Plate5">Fig. 5</a>. <em class="italic">A Pedestal Figure Lamp.</em> The gas is +here made to pass by means of a pipe through +the body of the figure into the lattice-work +<em class="italic">plateau</em>, constructed of hollow and perforated +brass tubes.</p> + +<p><a href="#Plate5">Fig. 6</a>. <em class="italic">A Pedestal Vase Lamp.</em> The gas-tube +enters through one of the claw-feet of the +altar-shaped pedestal, into the glass vase, <i>a</i>, at<span class="pagenum"><a name="Page_121" id="Page_121">[121]</a></span> +the bottom of which it joins the tubes communicating +with the metallic corn-ears, <i>b</i>, at the +upper extremities of which it forms <em class="italic">jets de feu</em>.</p> + +<p><a href="#Plate5">Fig. 7</a>. <em class="italic">A Girandole.</em> The gas enters through +the bracket, <i>a</i>, and is conveyed to the burners +by the descending tubes, <i>b</i> <i>b</i>.</p> + +<p><a href="#Plate5">Fig. 8</a>. <em class="italic">A Candelabrum</em>, having a central +pipe, through which the gas is conducted to +the burner at the top.</p> + +<hr class="sect" /> + +<h4><span class="fsize60">OTHER</span><br /> +PRODUCTS OBTAINABLE FROM COAL:<br /> +<span class="fsize60">NAMELY,</span><br /> +COKE, TAR, ESSENTIAL OIL, &c.</h4> + +<p>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.</p> + +<p><em class="italic">Coke.</em>—The substance called coke, which +constitutes the skeleton of the coal, or its carbonaceous +base, is left behind in the retort, after<span class="pagenum"><a name="Page_122" id="Page_122">[122]</a></span> +all the evaporable products have been expelled +from the coal by heat.—See <a href="#Page_85">page 85</a>.</p> + +<p>It is sufficiently known, that coke is a more +valuable fuel than the coal from which it is +obtained.</p> + +<p>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.<a name="FNanchor_27" id="FNanchor_27"></a><a href="#Footnote_27" class="fnanchor">[27]</a> In the manufacture<span class="pagenum"><a name="Page_123" id="Page_123">[123]</a></span> +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 <em class="italic">ennui</em> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_27" id="Footnote_27"></a><a href="#FNanchor_27"><span class="label">[27]</span></a> 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.</p></div> + +<p>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<span class="pagenum"><a name="Page_124" id="Page_124">[124]</a></span> +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.</p> + +<p>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.</p> + +<p>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 <em class="italic">very intense</em>, 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<span class="pagenum"><a name="Page_125" id="Page_125">[125]</a></span> +the fire, unless the bars of the grate be too +close together.</p> + +<p>The relative effects of heat produced by +coke and coal are as follows:—</p> + +<p>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.<a name="FNanchor_28" id="FNanchor_28"></a><a href="#Footnote_28" class="fnanchor">[28]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_28" id="Footnote_28"></a><a href="#FNanchor_28"><span class="label">[28]</span></a> 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, +</p> +<p> +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.</p></div> + +<p><span class="pagenum"><a name="Page_126" id="Page_126">[126]</a></span></p> + +<p>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.</p> + +<p>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 <em class="italic">third more lime</em> at the <em class="italic">same time</em>.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_127" id="Page_127">[127]</a></span></p> + +<p>The following account given by Mr. Davis,<a name="FNanchor_29" id="FNanchor_29"></a><a href="#Footnote_29" class="fnanchor">[29]</a> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_29" id="Footnote_29"></a><a href="#FNanchor_29"><span class="label">[29]</span></a> Philosophical Magazine, Vol. 33, p. 435.</p></div> + +<p>“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<span class="pagenum"><a name="Page_128" id="Page_128">[128]</a></span> +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.</p> + +<p>“On applying coke instead of coal, the +produce of lime may be increased to nearly 30<span class="pagenum"><a name="Page_129" id="Page_129">[129]</a></span> +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 <em class="italic">less attendance</em> and <em class="italic">less labour</em>, +and the whole saving, thus accomplished, +amounts to more than 50 <em class="italic">per cent. on the +lime-kiln</em>.</p> + +<p>“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.</p> + +<p>“If coke be applied instead of coal, the +arches, or empty spaces in the clamp or pile,<span class="pagenum"><a name="Page_130" id="Page_130">[130]</a></span> +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.</p> + +<p>“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.</p> + +<p>“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.”</p> + +<p>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,<span class="pagenum"><a name="Page_131" id="Page_131">[131]</a></span> +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.</p> + +<p><em class="italic">Coal-tar</em>, <em class="italic">Oil</em>, and <em class="italic">Pitch</em>.—Another, valuable +product obtainable from pit-coal, is coal-tar.<a name="FNanchor_30" id="FNanchor_30"></a><a href="#Footnote_30" class="fnanchor">[30]</a> +This substance is deposited, in the purification +of the coal-gas, in a separate vessel destined +to receive it.</p> + +<div class="footnote"> + +<p><a name="Footnote_30" id="Footnote_30"></a><a href="#FNanchor_30"><span class="label">[30]</span></a> 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.</p></div> + +<p>The coal-tar is so called from its resembling +common tar in its appearance, and most of its +qualities.</p> + +<p>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<span class="pagenum"><a name="Page_132" id="Page_132">[132]</a></span> +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.</p> + +<p>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.</p> + +<p>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 <a href="#Page_94">page 94</a>.</p> + +<p>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.</p> + +<p>To render the tar fit for use, it requires to +be evaporated to give it a sufficient consistence.<span class="pagenum"><a name="Page_133" id="Page_133">[133]</a></span> +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.</p> + +<p>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.</p> + +<p>Two hundred pounds of tar produce, upon +an average, fifty-three pounds of essential oil.</p> + +<p>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<span class="pagenum"><a name="Page_134" id="Page_134">[134]</a></span> +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.</p> + +<div class="figcenter"> +<p class="caption"><i>Kettle for boiling Tar.</i></p> +<img src="images/illo155.png" alt="" width="350" height="205" /> +</div> + +<p>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 <em class="italic">asphaltum</em>.</p> + +<p><em class="italic">Ammoniacal Fluid.</em>—The properties of the +ammoniacal liquor, which accompanies the tar,<span class="pagenum"><a name="Page_135" id="Page_135">[135]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_136" id="Page_136">[136]</a></span> +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.</p> + +<p>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 <em class="italic">fashion</em>.</p> + +<p>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,<span class="pagenum"><a name="Page_137" id="Page_137">[137]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_138" id="Page_138">[138]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_139" id="Page_139">[139]</a></span> +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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_140" id="Page_140">[140]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_141" id="Page_141">[141]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>If any additional want were wanted for the<span class="pagenum"><a name="Page_142" id="Page_142">[142]</a></span> +coke it will readily be found in the continental +market; coke being much better suited than +coal to the habits of most European nations.</p> + +<p>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.</p> + +<p>It is worthy observation, that the annual +importation of coal into this Metropolis, is +above one million and eighty-eight thousand +chaldrons.<a name="FNanchor_31" id="FNanchor_31"></a><a href="#Footnote_31" class="fnanchor">[31]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_31" id="Footnote_31"></a><a href="#FNanchor_31"><span class="label">[31]</span></a> 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, +</p> +<p> +<em class="italic">1st</em>. 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. +</p> +<p> +<em class="italic">2dly</em>. That this seam, on an average, is at least four feet +and a half thick. +</p> +<p> +<em class="italic">3dly</em>, That 1-6th part of the above extent is sufficient +for pillars to support the roofs of the mines, &c. +</p> +<p> +And, <em class="italic">4thly</em>, It appears, by experiments, that a cubic +yard of coal weighs 1 ton, or 20 cwt. +</p> + +<table summary="Table footnote 31"> + +<tr> +<td> </td> +<td class="center fsize80">London Chaldrons</td> +</tr> + +<tr> +<td class="just top padr3">The total consumption of coal from the rivers Tyne and Wear known from the register to be</td> +<td class="right bot">2,300,000</td> +</tr> + +<tr> +<td class="just top padr3">The number of tons in the above quantity taking the London chaldron at 27 cwt. is</td> +<td class="right bot">3,100,000</td> +</tr> + +<tr> +<td colspan="2" class="just top">Now a ton weight of coal is estimated to occupy in the earth the space of one cubic yard.</td> +</tr> + +<tr> +<td class="just top padr3">The number of cubic yards in the square mile is</td> +<td class="right bot">3,097,600</td> +</tr> + +<tr> +<td class="just top padr3">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</td> +<td class="right bot">1,548,800</td> +</tr> + +<tr> +<td class="just top padr3">And hence the square mile of the beds or seams of coal we are describing contains, of cubic yards and tons of coal</td> +<td class="right bot">4,645,000</td> +</tr> + +<tr> +<td class="just top padr3">A deduction of 1-6th for pillars to support the mine, &c.</td> +<td class="right bot">800,000</td> +</tr> + +<tr> +<td class="just top padr3">The number of tons per square mile</td> +<td class="right bot">5,445,000</td> +</tr> + +</table> + +<p> +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.</p></div> + +<p><span class="pagenum"><a name="Page_143" id="Page_143">[143]</a></span></p> + +<p>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<span class="pagenum"><a name="Page_144" id="Page_144">[144]</a></span> +illumination. But there are two reasons why +this should have less place, because we find, +in Mr. Murdoch’s statement, <a href="#Page_69">page 69</a>, 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.<a name="FNanchor_32" id="FNanchor_32"></a><a href="#Footnote_32" class="fnanchor">[32]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_32" id="Footnote_32"></a><a href="#FNanchor_32"><span class="label">[32]</span></a> See, also, Mr. Ackermann’s statement, <a href="#Page_71">page 71</a>.</p></div> + +<p><em class="italic">2dly</em>, 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,<span class="pagenum"><a name="Page_145" id="Page_145">[145]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_146" id="Page_146">[146]</a></span> +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.</p> + +<p>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.</p> + +<p>From experiments, made by Mr. <span class="smcap">Clegg</span>, on +the effects produced by a number of gas-lights, +of a certain intensity, there is reason to believe<span class="pagenum"><a name="Page_147" id="Page_147">[147]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_148" id="Page_148">[148]</a></span> +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,<a name="FNanchor_33" id="FNanchor_33"></a><a href="#Footnote_33" class="fnanchor">[33]</a> which is a practice commonly<span class="pagenum"><a name="Page_149" id="Page_149">[149]</a></span> +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<span class="pagenum"><a name="Page_150" id="Page_150">[150]</a></span> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_33" id="Footnote_33"></a><a href="#FNanchor_33"><span class="label">[33]</span></a> 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. +</p> +<p> +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. +</p> +<p> +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. +</p> +<p> +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. +</p> +<p> +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.</p></div> + +<p>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,<span class="pagenum"><a name="Page_151" id="Page_151">[151]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_152" id="Page_152">[152]</a></span> +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.</p> + +<p>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.</p> + +<p>Those who are familiar with the subject +will readily allow, that there is no more risk<span class="pagenum"><a name="Page_153" id="Page_153">[153]</a></span> +in the action of a gas-light machinery, properly +constructed, than there is in the action +of a steam-engine, built on just principles.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_154" id="Page_154">[154]</a></span> +as we depend on the light to be obtained from +a certain number of candles or oil-lamps.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_155" id="Page_155">[155]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_156" id="Page_156">[156]</a></span> +body, as has been stated, <a href="#Page_98">page 98</a>, 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<span class="pagenum"><a name="Page_157" id="Page_157">[157]</a></span> +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.</p> + +<p><span class="pagenum"><a name="Page_158" id="Page_158">[158]</a></span></p> + +<div class="london_b"><a name="FigLondon" id="FigLondon"></a> +<div class="ill_b"> + +<p class="fsize80 nowrap" style="padding-left: .5em; padding-top: .75em;">Main pipe, leading from the Gas-light station or +apparatus,<br />situated in Brick Lane, near Old St.<a name="FNanchor_34" id="FNanchor_34"></a><a href="#Footnote_34" class="fnanchor">[34]</a></p> + +<p class="fsize80 left" style="padding-left: 37em; padding-top: 3em;">Main pipe, leading from the gaslight apparatus, +or station, at Norton Falgate.<a name="FNanchor_35" id="FNanchor_35"></a><a href="#Footnote_35" class="fnanchor">[35]</a></p> + +<p class="fsize80 left" style="padding-left: .5em; padding-top: 12.5em;">Main pipe, leading from the gaslight apparatus, +or station,<br />in Westminster.<a name="FNanchor_36" id="FNanchor_36"></a><a href="#Footnote_36" class="fnanchor">[36]</a></p> + +</div><!--ill_b--> + +<div class="footnote"> + +<p><a name="Footnote_34" id="Footnote_34"></a><a href="#FNanchor_34"><span class="label">[34]</span></a> <em class="italic">The gasometer at this place is equal in capacity to 22000 cubic feet.</em></p> + +<p><a name="Footnote_35" id="Footnote_35"></a><a href="#FNanchor_35"><span class="label">[35]</span></a> <em class="italic">The capacity of the gasometer here is equal to 15928 cubic feet.</em></p> + +<p><a name="Footnote_36" id="Footnote_36"></a><a href="#FNanchor_36"><span class="label">[36]</span></a> <em class="italic">At this station the gasometer is equal in capacity to 14808 cubic feet.</em></p></div> + +</div><!--london_b--> + +<div class="london_e"> +<div class="ill_e"> +<img src="images/illo_e179.png" alt="Pipe network" width="500" height="385" /> +</div><!--ill_e--> + +<div class="footnote"> + +<p><span class="label">*</span> <em class="italic">The gasometer at this place is equal in capacity to 22000 cubic feet.</em></p> + +<p><span class="label">†</span> <em class="italic">The capacity of the gasometer here is equal to 15928 cubic feet.</em></p> + +<p><span class="label">‡</span> <em class="italic">At this station the gasometer is equal in capacity to 14808 cubic feet.</em></p></div> + +</div><!--london_e--> + +<p>The <a href="#FigLondon">black lines</a> 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, <em class="italic">Pall Mall</em>, should break, it is evident, +on mere inspection, that the gas which is<span class="pagenum"><a name="Page_159" id="Page_159">[159]</a></span> +passing through the main in the <em class="italic">Strand</em>, and +which is also connected with the main in the +<em class="italic">Haymarket</em>, <em class="italic">Piccadilly</em>, and <em class="italic">Coventry Street</em>, +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.</p> + +<p>Further, let us suppose a main pipe should +break in <em class="italic">Piccadilly</em>; in that case, the valve +being shut on each side of the fracture, the gas +would be supplied from the mains in the <em class="italic">Haymarket</em> +and <em class="italic">St. James’s Street</em>. 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<span class="pagenum"><a name="Page_160" id="Page_160">[160]</a></span> +streets.<a name="FNanchor_37" id="FNanchor_37"></a><a href="#Footnote_37" class="fnanchor">[37]</a> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_37" id="Footnote_37"></a><a href="#FNanchor_37"><span class="label">[37]</span></a> As shown in the <a href="#FigLondon">sketch</a>.</p></div> + +<p>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<span class="pagenum"><a name="Page_161" id="Page_161">[161]</a></span> +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.<a name="FNanchor_38" id="FNanchor_38"></a><a href="#Footnote_38" class="fnanchor">[38]</a> 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,<span class="pagenum"><a name="Page_162" id="Page_162">[162]</a></span> +as well as political recommendations, +for the adoption of the new lights in all manufactories +where work is done by candle-light.</p> + +<div class="footnote"> + +<p><a name="Footnote_38" id="Footnote_38"></a><a href="#FNanchor_38"><span class="label">[38]</span></a> Since the preceding pages have been printed, I have +seen a <em class="italic">self-extinguishing gas-lamp</em>, invented by Mr. <span class="smcap">Clegg</span>. +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. <span class="smcap">Clegg</span> 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.</p></div> + +<p>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<span class="pagenum"><a name="Page_163" id="Page_163">[163]</a></span> +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.</p> + +<p>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.</p> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_164" id="Page_164">[164]</a></span></p> + +<h3 class="noblank"><b>TABULAR VIEW,</b></h3> + +<p class="center fsize80">EXHIBITING</p> + +<p>The quantity of <span class="smcap">Gas</span>, <span class="smcap">Coke</span>, <span class="smcap">Tar</span>, <span class="smcap">Pitch</span>, <span class="smcap">Essential Oil</span>, and <span class="smcap">Ammoniacal Liquor</span>, obtainable from a given +quantity of <span class="smcap">Coal</span>; 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.</p> + +<table class="nowrap esmallest" summary="Table page 164"> + +<tr> +<th colspan="3"> </th> +<th colspan="14" class="center padl1 padr1 br"><em class="italic">Cost of Coal.</em></th> +<th colspan="8" class="center padl1 padr1 br"><em class="italic">Weight of Coal.</em></th> +<th colspan="6" class="center padl1 padr1"><em class="italic">Produce of Gas, in cubic feet.</em></th> +<td rowspan="8" class="bt br bb narrow"> </td> +<td rowspan="8" class="left padl0 narrow">-</td> +<td rowspan="8" class="left padl1 padr1 br wrappable"><a name="FNanchor_39" id="FNanchor_39"></a><a href="#Footnote_39" class="fnanchor">[39]</a>Equal to as many tallow candles, 12 in the pound, burning two hours; or to</td> +<th colspan="3" class="center padl1 padr1"><em class="italic">Candles.</em></th> +</tr> + +<tr> +<th colspan="3"> </th> +<th colspan="4" class="center padl1 padr1">Mini-<br />mum.</th> +<th> </th> +<th colspan="4" class="center padl1 padr1">Maxi-<br />mum.</th> +<th> </th> +<th colspan="4" class="center padl1 padr1 br">Aver-<br />age.</th> +<th colspan="2" class="center padl1 padr1">Min.</th> +<th> </th> +<th colspan="2" class="center padl1 padr1">Max.</th> +<th> </th> +<th colspan="2" class="center padl1 padr1 br">Aver.</th> +<th class="center padl1 padr1">Min.</th> +<th> </th> +<th class="center padl1 padr1">Max.</th> +<th> </th> +<th colspan="2" class="center padl1 padr1">Aver.</th> +<td class="right padl1 padr1">9,516<br />8,651</td> +<td class="right padr1">11<br />10</td> +<td class="left">to the pound.<br /><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td class="left">One Chal.<br />of Coal,<br />from 25<br />to 28 cwt.</td> +<td class="bt br bb narrow"> </td> +<td class="left padl0">-</td> +<td class="right padl1 padr0">40</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">to</td> +<td class="right padl1 padr0">60</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">—</td> +<td class="right padl1 padr0">50</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2" class="br"> </td> +<td class="right padl1 padr0">2,800</td> +<td> </td> +<td class="center">to</td> +<td class="right padl1 padr0">3,136</td> +<td> </td> +<td class="center">—</td> +<td class="right padl1 padr0">2,968</td> +<td class="br"> </td> +<td class="right padl1 padr1">8,906</td> +<td class="center">to</td> +<td class="right padl1 padr1">11,872</td> +<td class="center">—</td> +<td class="right padl1 padr0">10,388</td> +<td class="left padl0 padr0"><a href="#Footnote_39" class="fnanchor">[39]</a></td> +<td class="right padl1 padr1">7,786<br />6,921<br />6,556<br />5,194</td> +<td class="right padr1">10<br />9<br />8<br />7</td> +<td class="left"><span class="noshow">to th</span>do.<br /><span class="noshow">to th</span>do.<br /><span class="noshow">to th</span>do.<br /><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Ton</td> +<td class="right padl1 padr0">30</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">to</td> +<td class="right padl1 padr0">48</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">—</td> +<td class="right padl1 padr0">38</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">6</td> +<td class="left padl0 padr1 br"><i>d</i></td> +<td colspan="6"> </td> +<td class="right padl1 padr0">2,240</td> +<td class="br"> </td> +<td class="right padl1 padr1">6,720</td> +<td class="center">to</td> +<td class="right padl1 padr1">8,960</td> +<td class="center">—</td> +<td class="right padl1 padr0">7,840</td> +<td> </td> +<td class="right padl1 padr1">4,325</td> +<td class="right padr1">5</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Sack</td> +<td class="right padl1 padr0">3</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">4</td> +<td class="left padl0 padr1"><i>d</i></td> +<td class="center">to</td> +<td class="right padl1 padr0">5</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">—</td> +<td class="right padl1 padr0">4</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">2</td> +<td class="left padl0 padr1 br"><i>d</i></td> +<td class="right padl1 padr0">233</td> +<td> </td> +<td class="center">to</td> +<td class="right padr0">261</td> +<td> </td> +<td class="center">—</td> +<td class="right padl1 padr0">247</td> +<td class="br"> </td> +<td class="right padl1 padr1">741</td> +<td class="center">to</td> +<td class="right padl1 padr1">988</td> +<td class="center">—</td> +<td class="right padl1 padr0">814</td> +<td> </td> +<td class="right padl1 padr1">3,463</td> +<td class="right padr1">4</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Bushel</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">2</td> +<td class="left padl0 padr1"><i>d</i></td> +<td class="center">to</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">8</td> +<td class="left padl0 padr1"><i>d</i></td> +<td class="center">—</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">5</td> +<td class="left padl0 padr1 br"><i>d</i></td> +<td class="right padl1 padr0">78</td> +<td> </td> +<td class="center">to</td> +<td class="right padl1 padr0">87</td> +<td> </td> +<td class="center">—</td> +<td class="right padl1 padr0">82</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">247</td> +<td class="center">to</td> +<td class="right padl1 padr1">330</td> +<td class="center">—</td> +<td class="right padl1 padr0">290</td> +<td> </td> +<td class="right padl1 padr1">2,595</td> +<td class="right padr1">3</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Peck</td> +<td colspan="2"> </td> +<td class="right padl1 padr0">3</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center">to</td> +<td colspan="2"> </td> +<td class="right padr0">5</td> +<td class="left padl0 padr1"><i>d</i></td> +<td class="center">—</td> +<td colspan="2"> </td> +<td class="right padl1 padr0">4</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr0">19</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center">to</td> +<td class="right padl1 padr0">21</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>4</sub></td> +<td class="center">—</td> +<td class="right padl1 padr0">20</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr1">61</td> +<td class="center">to</td> +<td class="right padl1 padr1">82</td> +<td class="center">—</td> +<td class="right padl1 padr0">71</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">1,730</td> +<td class="right padr1">2</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Pound</td> +<td colspan="13"> </td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>4</sub></td> +<td colspan="6"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr1">3</td> +<td class="center">to</td> +<td class="right padl1 padr1">4</td> +<td class="center">—</td> +<td class="right padl1 padr0">3</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">866</td> +<td class="right padr1">1</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td class="blankabove"> </td> +<td colspan="36" class="just wrappable blankabove"><span class="smcap">Coke.</span>—One chaldron of coal, from 25 to 28 cwt. gives 1<sup>1</sup>⁄<sub>4</sub> to 1½ chaldron of Coke.</td> +</tr> + +<tr> +<td> </td> +<td colspan="36" class="just wrappable"><span class="smcap">Tar.</span>—One chaldron of coal, from 25 to 28 cwt. gives from 150 to 180lb. of Tar,<a href="#Footnote_39" class="fnanchor">[39]</a> or 15 to 18 ale gallons, 10lb. each.</td> +</tr> + +<tr> +<td> </td> +<td colspan="36" class="just wrappable"><span class="smcap">Ammoniacal Liquor.</span>—One chaldron of coal, gives from 220 to 240lb. of Ammoniacal Liquor, or 22 to 24 ale gallons.</td> +</tr> + +</table> + +<div class="footnote"> + +<p><a name="Footnote_39" id="Footnote_39"></a><a href="#FNanchor_39"><span class="label">[39]</span></a>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.</p></div> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_165" id="Page_165">[165]</a></span></p> + +<p class="center"><i>Tabular View, exhibiting the illuminating power of Coal-Gas, compared with the illuminating power +of Tallow Candles of different sizes.</i></p> + +<table class="nowrap" summary="Table page 165"> + +<tr> +<th colspan="11" class="center padl1 padr1">One chaldron of Coal produces, according to weight and quality,</th> +</tr> + +<tr class="fsize80"> +<th colspan="6"> </th> +<th class="center padl1 padr1">Burning.</th> +<th class="center padl1 padr1">Candles.</th> +<th class="right padl1 padr1">12 to 1lb.</th> +<th> </th> +<th class="right padl1 padr1">6 to 1lb.</th> +</tr> + +<tr> +<th colspan="4" class="center padl1 padr1 fsize80">Cubic feet of Gas.</th> +<th class="center padl1 padr1 fsize80">Average.</th> +<td class="right padr1">1</td> +<td class="center">hour</td> +<td class="center padl1 padr1">=</td> +<td class="right padr1">21,000</td> +<td class="center padl1 padr1">=</td> +<td class="right padl1 padr1">10,500</td> +</tr> + +<tr> +<td class="left">From</td> +<td class="right padl1 padr1">9,000</td> +<td class="center">to</td> +<td class="right padl1 padr1">12,000</td> +<td class="right padl1 padr1">10,500</td> +<td class="right padl1 padr1">2</td> +<td class="center">hours</td> +<td class="center">=</td> +<td class="right padl1 padr1">10,500</td> +<td class="center">=</td> +<td class="right padl1 padr1">5,250</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">6,000</td> +<td> </td> +<td class="right padl1 padr1">8,000</td> +<td class="right padl1 padr1">7,000</td> +<td class="right padl1 padr1">3</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">7,000</td> +<td class="center">=</td> +<td class="right padl1 padr1">3,500</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">4,500</td> +<td> </td> +<td class="right padl1 padr1">6,000</td> +<td class="right padl1 padr1">5,250</td> +<td class="right padl1 padr1">4</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">5,250</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,625</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">3,600</td> +<td> </td> +<td class="right padl1 padr1">4,800</td> +<td class="right padl1 padr1">4,400</td> +<td class="right padl1 padr1">5</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">4,400</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,200</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">3,000</td> +<td> </td> +<td class="right padl1 padr1">4,000</td> +<td class="right padl1 padr1">3,500</td> +<td class="right padl1 padr1">6</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">3,500</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,750</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">2,571</td> +<td> </td> +<td class="right padl1 padr1">3,428</td> +<td class="right padl1 padr1">3,005</td> +<td class="right padl1 padr1">7</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">3,005</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,502</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">2,250</td> +<td> </td> +<td class="right padl1 padr1">3,000</td> +<td class="right padl1 padr1">2,625</td> +<td class="right padl1 padr1">8</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,625</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,312</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">2,000</td> +<td> </td> +<td class="right padl1 padr1">2,666</td> +<td class="right padl1 padr1">2,333</td> +<td class="right padl1 padr1">9</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,333</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,166</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,800</td> +<td> </td> +<td class="right padl1 padr1">2,100</td> +<td class="right padl1 padr1">2,100</td> +<td class="right padl1 padr1">10</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,100</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,050</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,636</td> +<td> </td> +<td class="right padl1 padr1">2,191</td> +<td class="right padl1 padr1">1,913</td> +<td class="right padl1 padr1">11</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,913</td> +<td class="center">=</td> +<td class="right padl1 padr1">956</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,500</td> +<td> </td> +<td class="right padl1 padr1">2,000</td> +<td class="right padl1 padr1">1,750</td> +<td class="right padl1 padr1">12</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,750</td> +<td class="center">=</td> +<td class="right padl1 padr1">875</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,384</td> +<td> </td> +<td class="right padl1 padr1">1,846</td> +<td class="right padl1 padr1">1,615</td> +<td class="right padl1 padr1">13</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,615</td> +<td class="center">=</td> +<td class="right padl1 padr1">807</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,285</td> +<td> </td> +<td class="right padl1 padr1">1,714</td> +<td class="right padl1 padr1">1,499</td> +<td class="right padl1 padr1">14</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,499</td> +<td class="center">=</td> +<td class="right padl1 padr1">749</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,200</td> +<td> </td> +<td class="right padl1 padr1">1,600</td> +<td class="right padl1 padr1">1,400</td> +<td class="right padl1 padr1">15</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,400</td> +<td class="center">=</td> +<td class="right padl1 padr1">700</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,125</td> +<td> </td> +<td class="right padl1 padr1">1,500</td> +<td class="right padl1 padr1">1,312</td> +<td class="right padl1 padr1">16</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,312</td> +<td class="center">=</td> +<td class="right padl1 padr1">656</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,058</td> +<td> </td> +<td class="right padl1 padr1">1,111</td> +<td class="right padl1 padr1">1,234</td> +<td class="right padl1 padr1">17</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,234</td> +<td class="center">=</td> +<td class="right padl1 padr1">617</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,000</td> +<td> </td> +<td class="right padl1 padr1">1,333</td> +<td class="right padl1 padr1">1,166</td> +<td class="right padl1 padr1">18</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,166</td> +<td class="center">=</td> +<td class="right padl1 padr1">583</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">947</td> +<td> </td> +<td class="right padl1 padr1">1,263</td> +<td class="right padl1 padr1">1,105</td> +<td class="right padl1 padr1">19</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,105</td> +<td class="center">=</td> +<td class="right padl1 padr1">552</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">900</td> +<td> </td> +<td class="right padl1 padr1">1,200</td> +<td class="right padl1 padr1">1,050</td> +<td class="right padl1 padr1">20</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,050</td> +<td class="center">=</td> +<td class="right padl1 padr1">525</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">857</td> +<td> </td> +<td class="right padl1 padr1">1,143</td> +<td class="right padl1 padr1">1,000</td> +<td class="right padl1 padr1">21</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,000</td> +<td class="center">=</td> +<td class="right padl1 padr1">500</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">818</td> +<td> </td> +<td class="right padl1 padr1">1,095</td> +<td class="right padl1 padr1">956</td> +<td class="right padl1 padr1">22</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">956</td> +<td class="center">=</td> +<td class="right padl1 padr1">478</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">783</td> +<td> </td> +<td class="right padl1 padr1">1,044</td> +<td class="right padl1 padr1">913</td> +<td class="right padl1 padr1">23</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">913</td> +<td class="center">=</td> +<td class="right padl1 padr1">456</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">750</td> +<td> </td> +<td class="right padl1 padr1">1,000</td> +<td class="right padl1 padr1">875</td> +<td class="right padl1 padr1">21</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">875</td> +<td class="center">=</td> +<td class="right padl1 padr1">437</td> +</tr> + +</table> + +<p>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:</p> + +<table class="nowrap" summary="Table page 165-2"> + +<tr> +<td> </td> +<td class="right padl1 padr1">1</td> +<td class="center">lb.</td> +<td class="center padl1 padr1">=</td> +<td class="right">2968th</td> +<td class="left padl1">part of a chaldron.</td> +</tr> + +<tr> +<td class="left">One peck</td> +<td class="right padl1 padr1">20</td> +<td> </td> +<td class="center">=</td> +<td class="right">148th</td> +<td class="center">ditto.</td> +</tr> + +<tr> +<td class="left">One bushel</td> +<td class="right padl1 padr1">82</td> +<td> </td> +<td class="center">=</td> +<td class="right">36th</td> +<td class="center">ditto.</td> +</tr> + +<tr> +<td class="left">One sack</td> +<td class="right padl1 padr1">248</td> +<td> </td> +<td class="center">=</td> +<td class="right">12th</td> +<td class="center">ditto.</td> +</tr> + +</table> + +<p><span class="smcap">Rule.</span>—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.</p> + +<p><span class="smcap">Example.</span>—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.</p> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_166" id="Page_166">[166]</a></span></p> + +<h3>DESCRIPTION<br /> +<span class="fsize60">OF</span><br /> +THE GAS-LIGHT APPARATUS.</h3> + +<h4><a href="#Plate1">PLATE I.</a></h4> + +<p>Exhibits a perspective view of a gas-light apparatus,<a name="FNanchor_40" id="FNanchor_40"></a><a href="#Footnote_40" class="fnanchor">[40]</a> +for lighting factories, or small districts of +houses. It consists of the following parts: which +may be considered separately.</p> + +<div class="footnote"> + +<p><a name="Footnote_40" id="Footnote_40"></a><a href="#FNanchor_40"><span class="label">[40]</span></a> This apparatus was erected by Mr. <span class="smcap">Clegg</span>, and is now in +action at Mr. <span class="smcap">Ackerman</span>’s establishment, in this metropolis.</p></div> + +<p><a href="#Plate1"><span class="smcap">Fig.</span> 1.</a> The <em class="italic">Retort Furnace</em>, for distilling the +coals. It is built of brick-work. The bricks which +are exposed to the immediate action of the fire, +are <em class="italic">Welch tumps</em>, or fire-bricks; they are bedded +in clay, or Windsor loam.</p> + +<p><a href="#Plate1"><span class="smcap">Fig.</span> 2.</a> The <em class="italic">Tar Cistern</em>, 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.</p> + +<p><span class="pagenum"><a name="Page_167" id="Page_167">[167]</a></span></p> + +<p><a href="#Plate1"><span class="smcap">Fig.</span> 3.</a> The <em class="italic">Lime Machine</em>, for purifying the +crude coal-gas, and to render it fit for use. The +construction of this machine will be explained in +<a href="#Plate7">plate <span class="smcap">VII</span></a>. It is put together of cast-iron plates.</p> + +<p><a href="#Plate1"><span class="smcap">Fig.</span> 4.</a> The <em class="italic">Gasometer</em>, 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.</p> + +<p>The action of these different parts of the apparatus +will be obvious from the following explanation:</p> + +<p><span class="smcapall">A</span>, <span class="smcapall">A</span>, are two iron retorts, placed horizontally, +and side by side, in the furnace; the mouth of the<span class="pagenum"><a name="Page_168" id="Page_168">[168]</a></span> +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.</p> + +<p>When the operation commences, the inner vessel +of the gasometer, <a href="#Plate1">fig. 4</a> 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 <span class="smcapall">B</span>, <span class="smcapall">B</span>, into the horizontal pipe or main +condenser <span class="smcapall">C</span>, with which they are connected. The +liquid which is distilled, collects in the pipe, or +main condenser, <span class="smcapall">C</span>, where it is retained until its +quantity has risen so high as to discharge itself into +the pipe <span class="smcapall">D</span>, which is connected with the upper part +of one of the extremities of the condenser, <span class="smcapall">C</span>. One +of the extremities of the pipes, <span class="smcapall">B</span>, <span class="smcapall">B</span>, therefore become +immersed into the liquid contained in the +main condenser or pipe <span class="smcapall">C</span>, whilst the vaporous or +condensible fluid, after having overcome the pressure +there opposed to it, is transported into the pipe <span class="smcapall">E</span>, +which, after passing in a serpentine direction, <span class="smcapall">E</span>, <span class="smcapall">E</span>,<span class="pagenum"><a name="Page_169" id="Page_169">[169]</a></span> +&c. through the exterior vessel or cistern of the gasometer, +terminates in the tar-vessel, <a href="#Plate1">fig. 2</a>. Thus the +vaporous fluids are condensed by passing through the +serpentine pipe, <span class="smcapall">E</span>, <span class="smcapall">E</span>, &c. and become deposited in +the tar-cistern, <a href="#Plate1">fig. 2</a>; whilst the non-condensible or +gazeous products are made to proceed by the pipe <span class="smcapall">F</span>, +which branches off from the pipe <span class="smcapall">E</span>, into the lime +machine, <a href="#Plate1">fig. 3</a>. 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 <span class="smcapall">G</span>, +into the perpendicular pipe <span class="smcapall">H</span>, 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 <span class="smcapall">I</span>, 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 <span class="smcapall">H</span>, displaces the water from +the receiver <span class="smcapall">I</span>, 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 <span class="smcapall">I</span>, 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<span class="pagenum"><a name="Page_170" id="Page_170">[170]</a></span> +with this substance in the lime machine, <a href="#Plate1">fig. 3</a>. +After rising through the water in the gasometer +cistern, it enters into the gasometer, which then ascends +as the gas accumulates in it.</p> + +<p>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 <span class="smcapall">K</span>, to the burners, or main +pipe, which communicates with the gas burners or +lamps. <span class="smcapall">L</span>, 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, +<span class="smcapall">L</span>, may be conveyed by the curved pipe <span class="smcapall">M</span>, without +admitting common air. <span class="smcapall">N</span>, <span class="smcapall">N</span>, 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<span class="pagenum"><a name="Page_171" id="Page_171">[171]</a></span> +machine, the contents of which should be renewed +occasionally. This pipe also conveys the necessary +water into the barrel, <span class="smcapall">L</span>. <span class="smcapall">O</span>, is a waste-pipe, to convey +the water as it becomes impregnated with the +impurities of the gas, out of the gasometer cistern. +<span class="smcapall">P</span>, is an agitator, to stir up the contents of the lime +machine occasionally, <span class="smcapall">Q</span>, <span class="smcapall">Q</span>, are two iron rods, which +serve as stays to guide the motion of the gasometer. +<span class="smcapall">R</span>, 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. <span class="smcapall">S</span>, is the waste +pipe of the lime machine, to remove the insoluble +parts of the lime. <span class="smcapall">T</span>, 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. <span class="smcapall">U</span> 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.</p> + +<p>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<span class="pagenum"><a name="Page_172" id="Page_172">[172]</a></span> +the right-hand corner of <a href="#Plate7">plate VII.</a> 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.</p> + +<h4><a href="#Plate2">PLATE II.</a></h4> + +<p>Represents a Portable experimental Gas Apparatus +for exhibiting, in the small way, the general +nature of the gas-light illumination.—It is described +<a href="#Page_79">page 79</a>.</p> + +<h4><a href="#Plate3">PLATES III.</a> <a href="#Plate4">IV.</a> <a href="#Plate5">V.</a></h4> + +<p>Show designs of various kinds of Gas Lamps, +Chandeliers, Candelabras, &c.—See <a href="#Page_114">pages 114</a>, <a href="#Page_118">118</a>, +<a href="#Page_140">140</a>.</p> + +<h4><a href="#Plate6">PLATE VI.</a></h4> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 1.</a> Exhibits a design of the <em class="italic">gasometer +framing</em>, or <em class="italic">skeleton</em>, which serves to give stability +and strength to the gasometer. It consists of +wooden frame work, marked <span class="smcapall">A</span>, <span class="smcapall">A</span>, <span class="smcapall">A</span>, interlaced<span class="pagenum"><a name="Page_173" id="Page_173">[173]</a></span> +with iron rods, <span class="smcapall">B</span>, <span class="smcapall">B</span>, <span class="smcapall">B</span>, &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.</p> + +<p>The rest of the sketches represent various kinds +of gas pipes employed as <em class="italic">mains</em> for conveying the +gas, and the methods of connecting them.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 2.</a> Represents a longitudinal section of a +<em class="italic">Spigot</em> and <em class="italic">Faucet Pipe</em>. These kinds of pipes are +applicable in most cases as mains for conveying gas. +<span class="smcapall">A</span>, is called the spigot, and <span class="smcapall">B</span>, the faucet. They +are joined together, and made air tight, by iron +cement, the composition of which is as follows:</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_174" id="Page_174">[174]</a></span> +proportion of iron,) all the parts of which cohere +strongly together.</p> + +<p>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<sup>1</sup>⁄<sub>2</sub> inches deep, and has the spigot inserted +1<sup>1</sup>⁄<sub>2</sub> 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<sup>1</sup>⁄<sub>2</sub> +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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 3.</a> 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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 4.</a> Represents a longitudinal section of two +flanch pipes, and the modes of connecting them. +<span class="smcapall">A</span> and <span class="smcapall">B</span>, show the parts of the pipes; and <span class="smcapall">C</span> and +<span class="smcapall">D</span>, the flanches. These pipes are also joined together, +and rendered air-tight, by interposing between<span class="pagenum"><a name="Page_175" id="Page_175">[175]</a></span> +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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 5.</a> Profile view of the same kind of pipes +connected together, <span class="smcapall">A</span> and <span class="smcapall">B</span>, the pipes; <span class="smcapall">C</span> and <span class="smcapall">D</span>, +the flanches; <span class="smcapall">E</span> and <span class="smcapall">F</span>, the bolts.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 6.</a> 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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 7.</a> Exhibits the method of connecting spigot +and faucet pipes when they have a round turn. <span class="smcapall">A</span> +and <span class="smcapall">B</span>, the junctures of the pipes.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 8.</a> Represents a longitudinal section of the +mode of joining pipes by means of what is called +a <em class="italic">thimble joint</em>. The junctures of the pipes to be +connected, are made air tight, as mentioned already, +by iron cement. <span class="smcapall">A</span>, the thimble or small cylinder, +with projecting edges, which unites the pipes <span class="smcapall">B</span>, <span class="smcapall">C</span>.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 9.</a> 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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 10.</a> Section of the same.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 11.</a> Represents a profile view of what is +called the <em class="italic">saddle joint</em>. It is employed for taking +off a branch-pipe. The branch has a piece <span class="smcapall">A</span> <span class="smcapall">B</span>, +formed on its end, and fits round one-half of the +outside of the pipe from which it is to proceed. +<span class="smcapall">C</span>, is called the saddle, which fits round the other +half of the pipe. The parts are secured together<span class="pagenum"><a name="Page_176" id="Page_176">[176]</a></span> +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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 12.</a> Section of the saddle-joint.</p> + +<p>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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 13.</a> Shows a reservoir for collecting the water +of condensation which might accumulate in the +pipes. It consists of a receptacle, <span class="smcapall">A</span>, in which the +water may pass; <span class="smcapall">B</span>, 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.</p> + +<p><span class="pagenum"><a name="Page_177" id="Page_177">[177]</a></span></p> + +<h4><a href="#Plate7">PLATE VII.</a></h4> + +<p>Exhibits a perpendicular section of a gas-light +apparatus, calculated for lighting towns, or large +districts of streets and houses.</p> + +<p><a href="#Plate7"><span class="smcap">Fig.</span> 1.</a> 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. <span class="smcapall">A</span>, <span class="smcap">A,</span> shows two of the retorts +placed horizontally above each other; <span class="smcapall">B</span>, the fire-place; +<span class="smcapall">C</span>, the flue which causes the fire to circulate +round the retorts so as to heat them equally in +every part; <span class="smcapall">D</span>, the opening of the flue where the +fire passes into the chimney; <span class="smcapall">E</span>, the ash-pit; <span class="smcapall">F</span>, a +chamber in front of the retort furnace, into which +the orifice or mouth of the retorts project; <span class="smcapall">G</span>, <span class="smcapall">G</span>, the +doors of the chamber, to enable the workmen to +charge and discharge the retorts; <span class="smcapall">H</span>, a funnel shaped +hole at the floor of the chamber <span class="smcapall">F</span>, through which +the red hot coke as it is discharged from the retorts +passes into the arched vault <span class="smcapall">I</span>; <span class="smcapall">K</span>, the syphon tube; +<span class="smcapall">L</span>, the horizontal condenser<a name="FNanchor_41" id="FNanchor_41"></a><a href="#Footnote_41" class="fnanchor">[41]</a>—the action of both of +these pipes have been already explained, <a href="#Page_168">p. 168</a>; +<span class="smcapall">M</span>, main pipe, which conveys the liquid substances +from the condenser, to the tar cistern, <a href="#Plate7">fig. 3</a>, and<span class="pagenum"><a name="Page_178" id="Page_178">[178]</a></span> +which conducts also the gazeous products into the +lime machine, <a href="#Plate7">fig. 2</a>; <span class="smcapall">N</span> <span class="smcapall">N</span>, shows that part of the +pipe which is interposed between the tar cistern, +<a href="#Plate7">fig. 3</a>, and the condensing pipe <span class="smcapall">M</span>,—it passes in a +serpentine direction along the inner sides of the +gasometer cistern, and, like the so-called <em class="italic">worm</em> in +a distillatory apparatus, condenses the products +which escape in a vaporous state from the condenser +<span class="smcapall">L</span>; <span class="smcapall">O</span>, shows the place where the serpentine pipe +<span class="smcapall">N</span> <span class="smcapall">N</span>, passes again out of the gasometer cistern, and +its communication with the lime machine, <a href="#Plate7">fig. 2</a>, and +tar chamber, <a href="#Plate7">fig. 3</a>. The action of the lime machine +is as follows: The liquid products evolved from the +coal, having been deposited in the tar cistern, <a href="#Plate7">fig. 3</a>, +by means of the serpentine pipe <span class="smcapall">N</span>, <span class="smcapall">N</span>, the gazeous products +which accompany it, are conveyed by means of +the pipe <span class="smcapall">P</span>, which branches out from the pipe <span class="smcapall">O</span>, into +the interior receptacle of the lime machine marked <span class="smcapall">Q</span>, +which consists of a vessel open at the bottom, and +closed at the top, where it communicates with the +pipe <span class="smcapall">O</span>. As the gas accumulates in the interior part <span class="smcapall">Q</span>, +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 <span class="smcapall">R</span>, <span class="smcapall">R</span>, <span class="smcapall">R</span>, <span class="smcapall">R</span>, into the outer +vessel, <span class="smcapall">S</span>, of the lime machine and from thence it is +conducted away by the pipe <span class="smcapall">T</span>, <span class="smcapall">T</span>, <span class="smcapall">T</span>, into the additional +washing apparatus, of the gasometer; <a href="#Plate7">fig. 4</a>, +the construction of this apparatus, greatly resembles +the lime machine, <a href="#Plate7">fig. 2</a>, namely, <span class="smcapall">V</span>, is a water +pipe, proceeding from a cistern <span class="smcapall">U</span>, placed 3 or 4 feet +above the orifice of the pipe <span class="smcapall">V</span>; <span class="smcapall">T</span>, <span class="smcapall">T</span>, is the gas-pipe,<span class="pagenum"><a name="Page_179" id="Page_179">[179]</a></span> +covered with a hood, marked <span class="smcapall">W</span>, 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 <span class="smcapall">W</span>, meets with +a shower of water delivered by the pipe <span class="smcapall">V</span>. 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; <span class="smcapall">Y</span>, 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 <span class="smcapall">V</span>, 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 <span class="smcapall">L</span>, by means of the +pipe <span class="smcapall">K</span>, 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 <span class="smcapall">K</span>, <span class="smcapall">K</span>, becomes immersed and hermetically +sealed by the liquid which the condenser <span class="smcapall">L</span>, 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 <span class="smcapall">M</span>, from whence they are +transported into the tar cistern, <a href="#Plate7">fig. 3</a>, by means of +the system of pipes <span class="smcapall">N</span>, <span class="smcapall">N</span>, <span class="smcapall">O</span>, whilst the gazeous products +are made to pass by means of the branch +pipe <span class="smcapall">P</span>, into the lime machine, <a href="#Plate7">fig. 2</a>. From this +part of the apparatus the gas passes through the +pipe <span class="smcapall">T</span>, <span class="smcapall">T</span>, <span class="smcapall">T</span>, into the additional or smaller washing +apparatus placed upon a tressel in the cistern of the<span class="pagenum"><a name="Page_180" id="Page_180">[180]</a></span> +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 <span class="smcapall">A</span>, closed at the +top, and fixed in one corner of the gasometer, but +open at the bottom; it includes another pipe marked +<span class="smcapall">B</span>, which communicates with the main pipe leading +to the burners, or place where the gas is wanted. The +pipe <span class="smcapall">A</span>, which slides over the pipe <span class="smcapall">B</span>, is perforated at +the top, the gas passes through these perforations +and is thus made to enter into the pipe <span class="smcapall">B</span>, and +disposed of as mentioned. <span class="smcapall">C</span>, <span class="smcapall">C</span>, 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 <span class="smcapall">D</span>, which reaches +through the roof of the gasometer house, and thus +the superfluous quantity of gas is conveyed away +into the open air.</p> + +<div class="footnote"> + +<p><a name="Footnote_41" id="Footnote_41"></a><a href="#FNanchor_41"><span class="label">[41]</span></a> 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 <span class="smcapall">K</span>, <span class="smcapall">K</span>, and not to discharge itself into the pipe <span class="smcapall">M</span>, till +this has been effected. The partition is seen in the drawing.</p></div> + +<p>The cylindrical vessel <span class="smcapall">P</span>, of <a href="#Plate7">fig. 3</a>, surrounding +the orifice of the pipe <span class="smcapall">O</span>, which delivers the tar into +the tar cistern, <a href="#Plate7">fig. 3</a>, 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 +<span class="smcapall">L</span>, is placed, as shown in the drawing, higher +than the level of the water in the gasometer cistern,<span class="pagenum"><a name="Page_181" id="Page_181">[181]</a></span> +to allow a free descent of the distillatory liquids as +they pass from this vessel along into the pipes <span class="smcapall">M</span>, <span class="smcapall">N</span>, <span class="smcapall">O</span>, +&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—<span class="smcapall">E</span>, <span class="smcapall">E</span>, are two iron stays—<span class="smcapall">G</span>, <span class="smcapall">G</span>, are +friction wheels.</p> + +<hr class="sect" /> + +<h3 class="light"><i>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.</i><a name="FNanchor_42" id="FNanchor_42"></a><a href="#Footnote_42" class="fnanchor">[42]</a></h3> + +<div class="footnote"> + +<p><a name="Footnote_42" id="Footnote_42"></a><a href="#FNanchor_42"><span class="label">[42]</span></a> For this elegant contrivance we are also indebted to +Mr. <span class="smcap">Clegg</span>.</p></div> + +<p>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 <a href="#Page_88">p. 88</a>, and <a href="#Page_167">167</a>. To +render its pressure uniform, we first take the <em class="italic">absolute</em> +weight of that part of the gasometer which becomes +immersed in the water, and knowing the <em class="italic">specific +weight</em> 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<span class="pagenum"><a name="Page_182" id="Page_182">[182]</a></span> +of which the gasometer is composed. For example, +let us suppose that the part of the gasometer which +becomes immersed in water weighs 861 <i>lb.</i> 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<i>lb.</i> 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<i>lbs.</i> then the chain +of the gasometer equal in length to the height of +the gasometer, immersed into the water must weigh +224<i>lb.</i> 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.</p> + +<hr class="sect" /> + +<h3>DIRECTIONS TO WORKMEN<br /> +<span class="fsize60">ATTENDING</span><br /> +THE GAS-LIGHT APPARATUS<a name="FNanchor_43" id="FNanchor_43"></a><a href="#Footnote_43" class="fnanchor">[43]</a>.</h3> + +<div class="footnote"> + +<p><a name="Footnote_43" id="Footnote_43"></a><a href="#FNanchor_43"><span class="label">[43]</span></a> Copied from a printed direction drawn up by Mr. Clegg, +for the use of workmen.</p></div> + +<p>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<span class="pagenum"><a name="Page_183" id="Page_183">[183]</a></span> +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.</p> + +<p>The bridge or row of bricks of the flue <span class="smcapall">C</span>, 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.</p> + +<p>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<span class="pagenum"><a name="Page_184" id="Page_184">[184]</a></span> +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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_185" id="Page_185">[185]</a></span></p> + +<hr class="sect" /> + +<h3>ESTIMATE<br /> +<span class="fsize60">OF</span><br /> +THE PRICE<br /> +<span class="fsize60">OF</span><br /> +A GAS-LIGHT APPARATUS,<br /> +<span class="fsize80"><em class="italic">IF ERECTED IN LONDON</em>,</span></h3> + +<p class="center">Capable of affording, every 24 hours, Light equal to 40,000 Tallow +Candles, six in the pound, burning one hour.</p> + +<table summary="Table page 185"> + +<tr> +<th> </th> +<th class="center padl3 padr1">£.</th> +<th class="center padl1 padr1">s.</th> +</tr> + +<tr> +<td class="left top padr3">Gasometer, to contain 10,000 cubic feet of gas</td> +<td class="right bot padl1 padr1">236</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Wheel-work, regulating chain, ballance-weight for ditto, with wooden framing</td> +<td class="right bot padl1 padr1">160</td> +<td class="right bot padl1 padr1">11</td> +</tr> + +<tr> +<td class="left top padr3">Wrought iron cistern for gasometer—36 feet wide, 24 feet long and 16 feet deep</td> +<td class="right bot padl1 padr1">500</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="3" class="center">(<em class="italic">It would weigh about 16 tons.</em>)</td> +</tr> + +<tr> +<td class="left top padr3">Wooden framing built around it, to secure ditto</td> +<td class="right bot padl1 padr1">150</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Condenser, cistern and communicating pipes</td> +<td class="right bot padl1 padr1">126</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Lime machine, made of cast iron plates</td> +<td class="right bot padl1 padr1">82</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Gasometer-house, built of frame-work and weather-boarded</td> +<td class="right bot padl1 padr1">250</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Twenty-four retorts set in brick-work, with furnaces for ditto, compleat</td> +<td class="right bot padl1 padr1">336</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Sundries</td> +<td class="right bot padl1 padr1 bb">100</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td> </td> +<td class="right bot padl1 padr1">£ 1940</td> +<td class="right bot padl1 padr1">11</td> +</tr> + +</table> + +<hr class="tb" /> + +<p>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<i>l.</i> if erected in this metropolis.</p> + +<p><span class="pagenum"><a name="Page_186" id="Page_186">[186]</a></span></p> + +<h3 class="light">LONDON Price List of the most essential articles<a name="FNanchor_44" id="FNanchor_44"></a><a href="#Footnote_44" class="fnanchor">[44]</a> employed +in the erection of a Gas-Light apparatus.</h3> + +<div class="footnote"> + +<p><a name="Footnote_44" id="Footnote_44"></a><a href="#FNanchor_44"><span class="label">[44]</span></a> 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.</p></div> + +<table class="nowrap" summary="Table page 186-1"> + +<tr> +<th colspan="10" class="center">Sheet-iron pipes brazed.</th> +</tr> + +<tr> +<th colspan="3"> </th> +<th class="center padl1 padr1"><i>s.</i></th> +<th colspan="2" class="center padl1 padr1"><i>d.</i></th> +<th colspan="4"> </th> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1 narrow"><sup>1</sup>⁄<sub>4</sub></td> +<td class="left padr3">inch in diameter</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">4</td> +<td> </td> +<td class="center padl1 padr1">a foot</td> +<td rowspan="14" class="bt br bb narrow"> </td> +<td rowspan="14" class="left padl0 narrow">-</td> +<td rowspan="14" class="left wrappable">in 15<br />to 18<br />feet<br />lengths.</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>3</sup>⁄<sub>8</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">4</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">5</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>5</sup>⁄<sub>8</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">6</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>3</sup>⁄<sub>4</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">6</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>7</sup>⁄<sub>8</sub></td> +<td class="left padr3">ditto</td> +<td> </td> +<td class="right padl1 padr0">7</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">1</td> +<td> </td> +<td class="left padr3">inch, ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">7</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">1</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>4</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">9</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">1</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">10</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">1</td> +<td class="left padl0 padr1"><sup>3</sup>⁄<sub>4</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">11</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">2</td> +<td> </td> +<td class="left padr3">inch, ditto</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">2</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>4</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr0">4</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">2</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr0">5</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">3</td> +<td> </td> +<td class="left padr3">inch, ditto</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr0">6</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td colspan="3" class="left padr3">Copper pipes brazed <sup>1</sup>⁄<sub>4</sub> inch</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">4</td> +<td> </td> +<td class="center padl1 padr1">per foot</td> +<td colspan="3"> </td> +</tr> + +<tr> +<td colspan="3" class="left padr3">Ditto, ditto, ditto <sup>3</sup>⁄<sub>8</sub> inch</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">5</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +<td colspan="3"> </td> +</tr> + +<tr> +<td colspan="10" class="left">Gas-light cockspur burners with stop-cock 2s 6d to 3s 6d</td> +</tr> + +<tr> +<td colspan="10" class="left">Argand’s lamps, with glass-holders, from 3s to 4s 6d</td> +</tr> + +</table> + +<table class="nowrap notop" summary="Table page 186-2"> + +<tr> +<td class="left padr3">Cast-iron retorts, weighing 7 cwt. at 15s 6d per cwt</td> +<td class="right padr1 padl1">£5</td> +<td class="right padl1 padr1">8</td> +<td class="right padl1 padr1">6</td> +</tr> + +<tr> +<td class="left padr3">Mouth-piece for ditto, compleat</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr1">14</td> +<td class="right padl1 padr1">8</td> +</tr> + +<tr> +<td class="left padr3">Cast-iron door frames for retort furnace</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="4" class="left">Furnace bars 10s. per cwt.</td> +</tr> + +<tr> +<td colspan="4" class="left">Sheet iron for gazometer (No. 23) 24s. per cwt.</td> +</tr> + +<tr> +<td colspan="4" class="left">Gazometer chains, 5d per lb.</td> +</tr> + +<tr> +<td colspan="4" class="left">Ballance weights [Plates] for gazometer, 9l 10s per ton.</td> +</tr> + +<tr> +<td colspan="4" class="left">Cast-iron cistern plates</td> +</tr> + +<tr> +<td colspan="4" class="left">----------------------- smaller size for lime machine, 18l per ton.</td> +</tr> + +<tr> +<td colspan="4" class="left">----------------------- middling size for tar cistern, 16l ditto</td> +</tr> + +<tr> +<td colspan="4" class="left">----------------------- largest size for gazometer cistern 14l ditto</td> +</tr> + +</table> + +<table class="nowrap notop" summary="Table page 186-3"> + +<tr> +<td class="left">Cast-iron flanch pipes</td> +<td class="right padl1 padr0">2</td> +<td class="center narrow padl0 padr0">-</td> +<td colspan="2" class="left padl0 padr1">inch diameter, at</td> +<td class="right padr1">5s</td> +<td> </td> +<td class="left padl1 padr1">per yd. in</td> +<td class="right padr1">6</td> +<td class="left">feet lengths</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">3</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">6s</td> +<td> </td> +<td class="center">ditto</td> +<td class="right padr1">6</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">4</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">8s</td> +<td class="right padr1">6d</td> +<td class="center">ditto</td> +<td class="right padr1">9</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">5</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">10s</td> +<td> </td> +<td class="center">ditto</td> +<td class="right padr1">9</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">6</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">12s</td> +<td> </td> +<td class="center">ditto</td> +<td class="right padr1">9</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">7</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">13s</td> +<td class="right padr1">6d</td> +<td class="center">ditto</td> +<td class="right padr1">9</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">8</td> +<td rowspan="4" class="bt br bb narrow"> </td> +<td rowspan="4" class="left padl0 narrow">-</td> +<td rowspan="4" colspan="4" class="left">11l. 5s. per ton</td> +<td rowspan="4" class="right padr1">9</td> +<td rowspan="4" class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">9</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">10</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">11</td> +</tr> + +</table> + +<table class="nowrap notop" summary="Table page 186-4"> + +<tr> +<td class="left"><sup>1</sup>⁄<sub>2</sub> inch nuts, screws and washers to put iron pipes together</td> +<td class="right padl1 padr1">7d.</td> +<td class="center">per lb</td> +</tr> + +<tr> +<td class="left"><sup>5</sup>⁄<sub>8</sub> ditto</td> +<td class="right padl1 padr1">7d.</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="left"><sup>3</sup>⁄<sub>4</sub> ditto</td> +<td class="right padl1 padr1">6d.</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="left">English bar-iron</td> +<td class="right padl1 padr1">13l.</td> +<td class="center">per ton</td> +</tr> + +<tr> +<td class="left">Best, ditto</td> +<td class="right padl1 padr1">18l.</td> +<td class="center">ditto</td> +</tr> + +</table> + +<p class="center fsize150"><em class="italic">FINIS.</em></p> + +<div class="figcenter"><a name="Plate6" id="Plate6"></a> +<img src="images/illo208.jpg" alt="Gasometer frame and pipe connectors" width="364" height="600" /> +<p class="largeimg"><a href="images/lg208.jpg">Larger image</a> (345 kB)</p> +</div> + +<div class="figcenter"><a name="Plate7" id="Plate7"></a> +<img src="images/illo210.jpg" alt="Gas works" width="600" height="499" /> +<p class="largeimg"><a href="images/lg210.jpg">Larger image</a> (302 kB)</p> +</div> + +<div class="tnbottom"><a name="TN" id="TN"></a> + +<h2>Transcriber’s notes</h2> + +<p>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.<br /> +The errata have already been incorporated in the text; the error mentioned as occurring on page 24 actually occurs on page 22.<br /> +The original language, including inconsistencies in spelling, hyphenation, punctuation, formatting, etc. has been retained, except as mentioned below.<br /> +The e-reader cover image has been created for this project, and is placed in the public domain.<br /> +Unclear parts of the text have been checked against the on-line copy of this book of the Eidgenössische Technische Hochschule Zürich.<br /> +Fractions like <sup>1</sup>⁄<sub>2</sub> and 1-10th have both been retained.<br /> +Page 90, Van Dieman, Troostwyck: Jan Rudolph Deiman and Adriaan Paets van Troostwijk.</p> + +<p>Changes made to the text:<br /> +Obvious punctuation and typographical errors have been corrected silently.<br /> +Some footnotes, tables and illustrations have been moved; some tables have been re-arranged.</p> + +<p>Other changes:<br /> +Page 23: any surfaces changed to any surface<br /> +Page 26: opening or shuting changed to opening or shutting<br /> +Page 47: A New changed to A new<br /> +Page 48: trafic changed to traffic; footnote [10]: corporated changed to incorporated (cf. errata)<br /> +Page 53: This combustion changed to The combustion (cf. errata)<br /> +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)<br /> +Page 67: 1250 + 2 = 2500 changed to 1250 × 2 = 2500<br /> +Page 69: Mr. <span class="smcap">Lee</span> changed to “Mr. <span class="smcap">Lee</span> for consistency<br /> +Page 72: closing quote mark added to letter<br /> +Page 96: pure coal- changed to pure coal-gas<br /> +Page 102: sub acetate changed to sub-acetate<br /> +Page 118: ball 6 changed to ball <i>b</i><br /> +Page 119: <i>e</i>, are changed to <i>e</i> <i>e</i>, are<br /> +Page 125: 180 degree changed to 180 degrees (cf. errata); footnote [28]: may he compleatly changed to may be compleatly<br /> +Page 131: and make changed to and makes<br /> +Page 132: coal changed to coal-tar (cf. errata)<br /> +Page 158: Nortou Falgate changed to Norton Falgate; a about changed to about<br /> +Page 165, table: 10,509 changed to 10,500.</p> + +</div><!--tnbottom--> + +<div>*** END OF THE PROJECT GUTENBERG EBOOK 44567 ***</div> +</body> +</html> diff --git a/44567-h/images/cover.jpg b/44567-h/images/cover.jpg Binary files differnew file mode 100644 index 0000000..117a713 --- /dev/null +++ b/44567-h/images/cover.jpg diff --git a/44567-h/images/illo001.jpg b/44567-h/images/illo001.jpg Binary files differnew file mode 100644 index 0000000..1ff6e78 --- /dev/null +++ b/44567-h/images/illo001.jpg diff --git a/44567-h/images/illo037.png b/44567-h/images/illo037.png Binary files differnew file mode 100644 index 0000000..984631f --- /dev/null +++ b/44567-h/images/illo037.png diff --git a/44567-h/images/illo093.jpg b/44567-h/images/illo093.jpg Binary files differnew file mode 100644 index 0000000..991b5e2 --- /dev/null +++ b/44567-h/images/illo093.jpg diff --git a/44567-h/images/illo131.jpg b/44567-h/images/illo131.jpg Binary files differnew file mode 100644 index 0000000..1b3cf28 --- /dev/null +++ b/44567-h/images/illo131.jpg diff --git a/44567-h/images/illo137.jpg b/44567-h/images/illo137.jpg Binary files differnew file mode 100644 index 0000000..670c0d1 --- /dev/null +++ b/44567-h/images/illo137.jpg diff --git a/44567-h/images/illo140.jpg b/44567-h/images/illo140.jpg Binary files differnew file mode 100644 index 0000000..a296d59 --- /dev/null +++ b/44567-h/images/illo140.jpg diff --git a/44567-h/images/illo155.png b/44567-h/images/illo155.png Binary files differnew file mode 100644 index 0000000..ffac448 --- /dev/null +++ b/44567-h/images/illo155.png diff --git a/44567-h/images/illo208.jpg b/44567-h/images/illo208.jpg Binary files differnew file mode 100644 index 0000000..d26a772 --- /dev/null +++ b/44567-h/images/illo208.jpg diff --git a/44567-h/images/illo210.jpg b/44567-h/images/illo210.jpg Binary files differnew file mode 100644 index 0000000..90b7cc1 --- /dev/null +++ b/44567-h/images/illo210.jpg diff --git a/44567-h/images/illo_b179.png b/44567-h/images/illo_b179.png Binary files differnew file mode 100644 index 0000000..05c0801 --- /dev/null +++ b/44567-h/images/illo_b179.png diff --git a/44567-h/images/illo_e179.png b/44567-h/images/illo_e179.png Binary files differnew file mode 100644 index 0000000..4570d23 --- /dev/null +++ b/44567-h/images/illo_e179.png diff --git a/44567-h/images/lg001.jpg b/44567-h/images/lg001.jpg Binary files differnew file mode 100644 index 0000000..823d7ed --- /dev/null +++ b/44567-h/images/lg001.jpg diff --git a/44567-h/images/lg093.jpg b/44567-h/images/lg093.jpg Binary files differnew file mode 100644 index 0000000..7e0cd4b --- /dev/null +++ b/44567-h/images/lg093.jpg diff --git a/44567-h/images/lg131.jpg b/44567-h/images/lg131.jpg Binary files differnew file mode 100644 index 0000000..44b2ea2 --- /dev/null +++ b/44567-h/images/lg131.jpg diff --git a/44567-h/images/lg137.jpg b/44567-h/images/lg137.jpg Binary files differnew file mode 100644 index 0000000..1f99ce6 --- /dev/null +++ b/44567-h/images/lg137.jpg diff --git a/44567-h/images/lg140.jpg b/44567-h/images/lg140.jpg Binary files differnew file mode 100644 index 0000000..95bc5d2 --- /dev/null +++ b/44567-h/images/lg140.jpg diff --git a/44567-h/images/lg208.jpg b/44567-h/images/lg208.jpg Binary files differnew file mode 100644 index 0000000..bd5424c --- /dev/null +++ b/44567-h/images/lg208.jpg diff --git a/44567-h/images/lg210.jpg b/44567-h/images/lg210.jpg Binary files differnew file mode 100644 index 0000000..c683551 --- /dev/null +++ b/44567-h/images/lg210.jpg diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..fc00df3 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #44567 (https://www.gutenberg.org/ebooks/44567) diff --git a/old/44567-0.txt b/old/44567-0.txt new file mode 100644 index 0000000..d9242d3 --- /dev/null +++ b/old/44567-0.txt @@ -0,0 +1,4958 @@ +Project Gutenberg's A Practical Treatise on Gas-light, by Fredrick Accum + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. 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: UTF-8 + +*** 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. + +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 1½ | 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 15¾ | 1 | 8 | + | 3 {| 3 | 3 0 | 1 2 | 1⅛ | 8¾ | + | {| Mould | 3 0 | 0 0 | 1 | 9 | + +-----------+--------+--------+----------+--------+---------+ + | 4 {| 5 | 3 0 | 1 5 | 1.18 | 8¾ | + | {| Mould | 3 0 | 1 1⅛ | 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| 18¾ | 0 14 | 3 15 | 59 26 | 9.70 | + |wick. | 19 | 0 13½ | 2 40 | 50 34 | 11.40 | + |A large| 16½ | 0 15½ | 2 40 | 44 2 | 13.08 | + |wick. | 12 | 1 5¼ | 3 27 | 41 24 | 13.92 | + | | 10¾ | 1 8 | 3 36 | 38 24 | 15.00 | + | | 7¾ | 2 1 | 4 9 | 32 12 | 17.88 | + | | 8 | 2 0 | 4 15 | 34 0 | 16.94 | + | | 5¾ | 2 13 | 5 19 | 30 15 | 19.06 | + | |Mould | | | |Moulds at 14d. | + | |candles. | Each. | | | per dozen. | + |With | 3⅞ | 2 12 | 7 20 | 42 39 | 15.74 | + |wax’d | 4 | 4 0 | 9 3 | 36 20 | 18.56 | + |wick. | 3 | 5 2¾ |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 +13½_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 4¾ pecks of + coke and ½ 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 = +17½lbs. 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. ½7 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 | 3½ to 5_d_ -- 4¼ + One Pound | ¼ + -----------+------------------------------------------ + + -----------+----------------------------------- + | _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 -- 82½ + One Peck | 19½ to 21¼ -- 20¼ + 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 -- 71½ + One Pound | 3 to 4 -- 3½ + -----------+-------------------------------- + + -----------+----------------------------------------- + | } |_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 1¼ to 1½ + 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 2½ inches deep, and has +the spigot inserted 1½ 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 1½ 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._ + ¼ inch in diameter 0 4 a foot} + ⅜ ditto 0 4 ditto} + ½ ditto 0 5 ditto} + ⅝ ditto 0 6 ditto} + ¾ ditto 0 6½ ditto} in + ⅞ ditto 7 ditto} 15 + 1 inch, ditto 0 7½ ditto} to + 1¼ ditto 0 9 ditto} 18 + 1½ ditto 0 10½ ditto} feet + 1¾ ditto 0 11 ditto} lengths. + 2 inch, ditto 1 1½ ditto} + 2¼ ditto 1 4 ditto} + 2½ ditto 1 5 ditto} + 3 inch, ditto 1 6½ ditto} + Copper pipes brazed ¼ inch 0 4 per foot + Ditto, ditto, ditto ⅜ inch 0 5½ 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} + ½ inch nuts, screws and washers to put iron pipes together 7d. per lb + ⅝ ditto 7d. ditto + ¾ 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 ½ 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 44567-0.txt or 44567-0.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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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 Lam 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 LINNN 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_ : Q [::] + _b_ : (_b_ + Q)/_a_ = 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_ + Q)/_a_ (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 _navet_ 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 RAckermann'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 Eidgenssische Technische Hochschule Zrich. + +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 Lam 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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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 Lam and the Online +Distributed Proofreading Team at http://www.pgdp.net (This +file was produced from images generously made available +by The Internet Archive) + + + + + + +</pre> + + +<div class="tnbox"> +<p class="center">Please see the <a href="#TN">Transcriber’s Notes</a> at the end of this text.</p> +</div> + +<div class="figcenter"><a name="Plate1" id="Plate1"></a> +<img src="images/illo001.jpg" alt="Gas plant" width="600" height="469" /> +<p class="largeimg"><a href="images/lg001.jpg">Larger image</a> (546 kB)</p> +</div> + +<h1><span class="fsize40">A</span><br /> +<span class="fsize80">PRACTICAL TREATISE</span><br /> +<span class="fsize40">ON</span><br /> +<span class="fsize150"><b>GAS-LIGHT;</b></span><br /> +<span class="fsize40">EXHIBITING</span><br /> +<span class="fsize80">A SUMMARY DESCRIPTION</span><br /> +<span class="fsize40">OF THE</span><br /> +APPARATUS AND MACHINERY<br /> +<span class="fsize40">BEST CALCULATED FOR</span><br /> +<span class="gesp">ILLUMINATING</span><br /> +<span class="fsize80">STREETS, HOUSES, AND MANUFACTORIES,</span><br /> +<span class="fsize40">WITH</span><br /> +<span class="fsize80">CARBURETTED HYDROGEN, OR COAL-GAS,</span><br /> +WITH REMARKS<br /> +<span class="fsize40">ON THE</span><br /> +<span class="fsize60">UTILITY, SAFETY, AND GENERAL NATURE OF THIS NEW BRANCH<br /> +OF CIVIL ECONOMY.</span></h1> + +<hr class="sect" /> + +<p class="center highline"><span class="fsize125"><span class="smcap">By</span> FREDRICK ACCUM,</span><br /> +<i>OPERATIVE CHEMIST</i>,<br /> +<span class="fsize80">LECTURER ON PRACTICAL CHEMISTRY, ON MINERALOGY, AND ON CHEMISTRY<br /> +APPLIED TO THE ARTS AND MANUFACTURES; MEMBER OF THE ROYAL<br /> +IRISH ACADEMY, FELLOW OF THE LINNÆN SOCIETY, MEMBER<br /> +OF THE ROYAL ACADEMY OF SCIENCES OF BERLIN, &c. &c.</span></p> + +<hr class="sect" /> + +<p class="center fsize125">WITH SEVEN COLOURED PLATES.</p> + +<hr class="sect" /> + +<p class="center"><span class="oldtype fsize125">London:</span><br /> +<span class="fsize80">PRINTED BY G. HAYDEN, BRYDGES-STREET, COVENT GARDEN;<br /> +FOR R. ACKERMANN, 101, STRAND;<br /> +<i>LONGMAN, HURST, REES, ORME, AND BROWN; AND SHERWOOD, NEELY, AND<br /> +JONES, PATERNOSTER ROW; AND J. HATCHARD, PICCADILLY</i>.</span></p> + +<p class="center"><em class="italic">Price—Twelve Shillings in Boards.</em></p> + +<hr class="sect" /> + +<p class="center">1815.</p> + +<hr class="chap" /> + +<p class="motto center">EX FUMO DARE LUCEM.</p> + +<p class="motto right"><span class="smcap">Hor.</span></p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_i1" id="Page_i1">[i]</a></span></p> + +<h2>PREFACE.</h2> + +<p class="rightsig"><i>11, Compton Street Soho.</i></p> + +<p>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 <span class="smcap">Gas-Light</span>.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_ii1" id="Page_ii1">[ii]</a></span> +products it furnishes—the modes of obtaining +them—their properties and applications in the various +arts of life.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_iii1" id="Page_iii1">[iii]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p class="rightsig gesp blankabove">FREDRICK ACCUM</p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_i2" id="Page_i2">[i]</a></span></p> + +<h2 class="oldtype">Contents.</h2> + +<table class="toc" summary="ToC"> + +<tr> +<td class="secname"><b>INTRODUCTORY OBSERVATION.</b></td> +<td class="pagenr">Page</td> +<td class="pagenr"><a href="#Page_1">1.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.—Extraordinary discoveries of modern +times.—New art of procuring light.—Object of the treatise.</td> +</tr> + +<tr> +<td colspan="3" class="partnr">PART I.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>PRODUCTION OF ARTIFICIAL LIGHT, &c.</b></td> +<td class="pagenr"><a href="#Page_8">8.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>METHOD OF ASCERTAINING THE ILLUMINATING +POWER OF CANDLES, LAMPS, AND +OTHER LUMINOUS BODIES.</b></td> +<td class="pagenr"><a href="#Page_22">22.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="3" class="partnr">PART II.<span class="pagenum"><a name="Page_ii2" id="Page_ii2">[ii]</a></span></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>GAS-LIGHT.</b></td> +<td class="pagenr"><a href="#Page_47">47.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>THEORY OF THE COMBUSTION OF COAL IN +ELUCIDATION OF THE NATURE OF GAS-LIGHT.</b></td> +<td class="right bot"><a href="#Page_49">49.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>HISTORICAL SKETCH OF THE RISE AND PROGRESS +OF THE APPLICATION OF COAL-GAS +AS A SUBSTITUTE FOR PROCURING ARTIFICIAL +LIGHT.</b></td> +<td class="pagenr"><a href="#Page_55">55.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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. <span class="smcap">Clayton</span>, +Dr. <span class="smcap">Hales</span>, and the Bishop of Llandaff.—First successful +attempt of lighting manufactories with gas.—<em class="italic">Creditor</em> and <em class="italic">debtor</em> +account concerning the expence of this mode of illumination, +when compared with the light obtained by tallow candles.—Claims +of Mr. <span class="smcap">Murdoch</span> with regard to the economical application +of coal-gas.—Claims of Mr. <span class="smcap">Winsor</span>.—Experiments +of Mr. <span class="smcap">Northern</span>, Mr. <span class="smcap">Clegg</span>, Mr. <span class="smcap">Cook</span>, Mr. <span class="smcap">Ackermann</span>.—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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>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.</b><span class="pagenum"><a name="Page_iii2" id="Page_iii2">[iii]</a></span></td> +<td class="pagenr"><a href="#Page_77">77.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>UTILITY OF THE GAS-LIGHT ILLUMINATION +WITH REGARD TO PUBLIC AND PRIVATE +ECONOMY.</b></td> +<td class="pagenr"><a href="#Page_99">99.</a></td> +</tr> + +<tr> +<td colspan="3" class="just">Objects to which the new system of lighting with gas may be beneficially +applied.—Capital advantages of the gas-light illumination.—Places +and public edifices lighted with coal-gas in this metropolis.—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 observations +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 obtainable from coal +besides gas.—<em class="italic">Coke.</em>—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.—Disadvantages +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 producing 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 +<span class="pagenum"><a name="Page_iv2" id="Page_iv2">[iv]</a></span>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.—<em class="italic">Coal tar.</em>—How obtained.—Its properties.—Earl +of Dundonald’s method of manufacturing 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.—<em class="italic">Coal +pitch.</em>—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.—<em class="italic">Ammoniacal liquor</em> 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.—Management 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 concerning 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, +<span class="pagenum"><a name="Page_v2" id="Page_v2">[v]</a></span>&c.—Produce no embers or sparks.—Cannot fall, or be disturbed +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-extinguishing lamp, invented by Mr. <span class="smcap">Clegg</span>.—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 <em class="italic">main</em>.—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.</td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>TABULAR VIEW</b>, Exhibiting the quantity of <span class="smcap">Gas</span>, <span class="smcap">Coke</span>, +<span class="smcap">Tar</span>, <span class="smcap">Pitch</span>, <span class="smcap">Essential Oil</span>, and <span class="smcap">Ammoniacal Liquor</span>, obtainable +from a given quantity of <span class="smcap">Coal</span>: 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.</td> +<td class="pagenr"><a href="#Page_164">164.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>DESCRIPTION OF THE GAS-LIGHT APPARATUS.</b></td> +<td class="pagenr"><a href="#Page_166">166.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>METHOD</b> of correcting the relative pressure of the Gasometer, +so as to cause the gas which it contains to be uniformly of an +equal density.</td> +<td class="pagenr"><a href="#Page_181">181.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>DIRECTIONS TO WORKMEN ATTENDING THE +GAS-LIGHT APPARATUS.</b></td> +<td class="pagenr"><a href="#Page_182">182.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>ESTIMATE</b> of the price of a Gas-Light Apparatus.</td> +<td class="pagenr"><a href="#Page_185">185.</a></td> +</tr> + +<tr> +<td colspan="2" class="secname"><b>LONDON</b> Price List of the most essential articles employed in +the erection of a Gas-light Apparatus.</td> +<td class="pagenr"><a href="#Page_186">186.</a></td> +</tr> + +</table> + +<hr class="sect" /> + +<h2 class="small">ERRATA.</h2> + +<table class="fsize80" summary="Errata"> + +<tr> +<td class="left top padr1">Page</td> +<td class="right top">24,</td> +<td class="left top padl1 padr1">line</td> +<td class="right top">11,</td> +<td class="left top padl1"><em class="italic">for</em> too, <em class="italic">read</em> two.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">48,</td> +<td> </td> +<td class="right top">22,</td> +<td class="left top padl1"><em class="italic">for</em> corporated, <em class="italic">read</em> incorporated.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">53,</td> +<td> </td> +<td class="right top">7,</td> +<td class="left top padl1"><em class="italic">for</em> this combustion, <em class="italic">read</em> the combustion.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">64,</td> +<td> </td> +<td class="right top">24,</td> +<td class="left top padl1"><em class="italic">for</em> <span class="smcap">Cleg</span>, <em class="italic">read</em> <span class="smcap">Clegg</span>.</td> +</tr> + +<tr> +<td> </td> +<td class="right top"><em class="italic">ibid</em></td> +<td> </td> +<td class="right top">25,</td> +<td class="left top padl1"><em class="italic">for</em> communicates, <em class="italic">read</em> communicated.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">65,</td> +<td colspan="2"> </td> +<td class="left top padl1">erase the * and put it after the word <span class="smcap">Clegg</span>, line 24, p. 64.</td> +</tr> + +<tr> +<td> </td> +<td class="right top"><em class="italic">ibid</em></td> +<td> </td> +<td class="right top">17,</td> +<td class="left top padl1"><em class="italic">for</em> attemps, <em class="italic">read</em> attempts.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">125,</td> +<td> </td> +<td class="right top">23,</td> +<td class="left top padl1"><em class="italic">for</em> degree, <em class="italic">read</em> degrees.</td> +</tr> + +<tr> +<td> </td> +<td class="right top">132,</td> +<td> </td> +<td class="right top">25,</td> +<td class="left top padl1"><em class="italic">for</em> coal, <em class="italic">read</em> coal-tar.</td> +</tr> + +</table> + +<hr class="sect" /> + +<h2 class="small">DIRECTIONS TO THE BINDER:</h2> + +<p class="fsize80"><a href="#Plate1">Plate I.</a> facing the title; <a href="#Plate2">plate II.</a> facing page 79; <a href="#Plate3">plate III.</a> facing page 115; +<a href="#Plate4">plate IV.</a> facing page 119; <a href="#Plate5">plate V.</a> facing page 120; and <a href="#Plate6">plates VI.</a> +and <a href="#Plate7">VII.</a> at the end of the book.</p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_1" id="Page_1">[1]</a></span></p> + +<p class="pseudoh1">A<br /> +<span class="fsize150">PRACTICAL TREATISE</span><br /> +ON<br /> +<span class="fsize175">GAS-LIGHT.</span></p> + +<hr class="chap" /> + +<h2>INTRODUCTORY OBSERVATION.</h2> + +<hr class="sect" /> + +<h3>INFLUENCE<br /> +<span class="fsize60">OF</span><br /> +THE PROGRESS OF THE ARTS<br /> +<span class="fsize60">UPON THE</span><br /> +MORALS AND CONDITION OF MAN.</h3> + +<p class="largecap">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<span class="pagenum"><a name="Page_2" id="Page_2">[2]</a></span> +civilization is, and ought ever to be, estimated +by the proportional state of industry, and useful +labour existing among them.</p> + +<p>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 <span class="smcap">Smith</span><a name="FNanchor_1" id="FNanchor_1"></a><a href="#Footnote_1" class="fnanchor">[1]</a> +emphatically remarks, that “the accommodation +of an European prince does not +always so much exceed that of an industrious<span class="pagenum"><a name="Page_3" id="Page_3">[3]</a></span> +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.”</p> + +<div class="footnote"> + +<p><a name="Footnote_1" id="Footnote_1"></a><a href="#FNanchor_1"><span class="label">[1]</span></a> Wealth of Nations, chap. 1.</p></div> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_4" id="Page_4">[4]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_5" id="Page_5">[5]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_6" id="Page_6">[6]</a></span> +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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_7" id="Page_7">[7]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_8" id="Page_8">[8]</a></span></p> + +<h2>PART I.</h2> + +<hr class="chap" /> + +<h3>PRODUCTION<br /> +<span class="fsize60">OF</span><br /> +ARTIFICIAL LIGHT;<br /> +<span class="fsize60">AND</span><br /> +<span class="gesp">THEORY</span><br /> +<span class="fsize60">OF THE</span><br /> +ACTION OF CANDLES AND LAMPS.</h3> + +<p>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<span class="pagenum"><a name="Page_9" id="Page_9">[9]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_10" id="Page_10">[10]</a></span> +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.</p> + +<p>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,<span class="pagenum"><a name="Page_11" id="Page_11">[11]</a></span> +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.</p> + +<p>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.</p> + +<p>That in many cases the light evolved by artificial +means is derived from the combustible<span class="pagenum"><a name="Page_12" id="Page_12">[12]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_13" id="Page_13">[13]</a></span> +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.<a name="FNanchor_2" id="FNanchor_2"></a><a href="#Footnote_2" class="fnanchor">[2]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_2" id="Footnote_2"></a><a href="#FNanchor_2"><span class="label">[2]</span></a> See Chemical Amusement, comprising minute instructions +for performing a series of striking and interesting +chemical experiments, p. 8, &c.</p></div> + +<p>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<span class="pagenum"><a name="Page_14" id="Page_14">[14]</a></span> +the new system of illumination which it is the +object of this Essay to explain.</p> + +<p>To procure light for the ordinary purposes +of life, we are acquainted with no other ready +means than the process of combustion.</p> + +<p>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.</p> + +<p>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.</p> + +<p>All these substances must be rendered volatile +before they can produce a flame, but for +this purpose it is sufficient to volatilize a small<span class="pagenum"><a name="Page_15" id="Page_15">[15]</a></span> +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 <em class="italic">wick</em>, +which in fact is the fire-place, or laboratory +where the whole operation is conducted.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_16" id="Page_16">[16]</a></span> +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,<span class="pagenum"><a name="Page_17" id="Page_17">[17]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_18" id="Page_18">[18]</a></span> +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<span class="pagenum"><a name="Page_19" id="Page_19">[19]</a></span> +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<span class="pagenum"><a name="Page_20" id="Page_20">[20]</a></span> +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<span class="pagenum"><a name="Page_21" id="Page_21">[21]</a></span> +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. +<span class="smcap">Nicholson</span><a name="FNanchor_3" id="FNanchor_3"></a><a href="#Footnote_3" class="fnanchor">[3]</a> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_3" id="Footnote_3"></a><a href="#FNanchor_3"><span class="label">[3]</span></a> Philosophical Journal, 4to Series, Vol. I. p. 70.</p> + +</div> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_22" id="Page_22">[22]</a></span></p> + +<h3>METHOD<br /> +<span class="fsize60">OF</span><br /> +ASCERTAINING THE ILLUMINATING POWER<br /> +<span class="fsize60">OF</span><br /> +CANDLES, LAMPS, GAS-LIGHTS,<br /> +<span class="fsize60">AND</span><br /> +OTHER LUMINOUS BODIES.</h3> + +<p>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.</p> + +<p>For this purpose it is assumed as a principle, +that the same quantity of light, diverging in<span class="pagenum"><a name="Page_23" id="Page_23">[23]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_24" id="Page_24">[24]</a></span> +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;</p> + +<div class="figcenter"> +<img src="images/illo037.png" alt="Overlapping shadows" width="200" height="133" /> +</div> + +<p><span class="pagenum"><a name="Page_25" id="Page_25">[25]</a></span></p> + +<p>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<span class="pagenum"><a name="Page_26" id="Page_26">[26]</a></span> +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.</p> + +<p>From experiments made by Count <span class="smcap">Rumford</span>, +concerning the quantity of materials requisite +for producing a light of a certain intensity for<span class="pagenum"><a name="Page_27" id="Page_27">[27]</a></span> +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.<a name="FNanchor_4" id="FNanchor_4"></a><a href="#Footnote_4" class="fnanchor">[4]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_4" id="Footnote_4"></a><a href="#FNanchor_4"><span class="label">[4]</span></a> 112lbs. of Newcastle coal, called Tanfield Moor, produce, +upon an average, from 250 to 300 cubic feet of gas, +fit for illumination.</p></div> + +<hr class="sect" /> + +<h4>FURTHER ILLUSTRATIONS<br /> +<span class="fsize60">OF THE</span><br /> +<span class="fsize60">MODE OF COMPUTING THE RELATIVE COST OR VALUE</span><br /> +<span class="fsize60">OF</span><br /> +LIGHT,<br /> +<span class="fsize60">EMITTED BY MEANS OF</span><br /> +CANDLES, LAMPS, & OTHER BODIES.</h4> + +<p>It is sufficiently known that the light of a +candle, which is so exceedingly brilliant when +first snuffed, is very speedily diminished to<span class="pagenum"><a name="Page_28" id="Page_28">[28]</a></span> +one-half and is usually not more than one-fifth +or one-sixth before the uneasiness of the eye +induces us to snuff it.<a name="FNanchor_5" id="FNanchor_5"></a><a href="#Footnote_5" class="fnanchor">[5]</a> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_5" id="Footnote_5"></a><a href="#FNanchor_5"><span class="label">[5]</span></a> Ezekiel Walker.—Nicholson’s Journal, Vol. IV. 8vo. +Series.</p></div> + +<p>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.</p> + +<p>To prove the truth of this position, Mr. +Walker made the experiments contained in +the following</p> + +<p><span class="pagenum"><a name="Page_29" id="Page_29">[29]</a></span></p> + +<p class="center">TABLE.</p> + +<table class="nowrap" summary="Table page 29"> + +<tr class="bt bb"> +<th colspan="4" class="center padl1 padr1 bl br">No. of<br />the<br />Experi-<br />ment.</th> +<th class="center padl1 padr1 br">No. of the<br />Candles.</th> +<th colspan="2" class="center padl1 padr1 br">Time of<br />burning.</th> +<th colspan="3" class="center padl1 padr1 br">Weight<br />of the<br />Candles<br />consumed<br />in a given<br />time.</th> +<th colspan="2" class="center padl1 padr1 br">Strength<br />of Light.</th> +<th colspan="2" class="center padl1 padr1 br">Distance<br />of the<br />Candles<br />from the<br />Wall.</th> +</tr> + +<tr> +<th colspan="4" class="bl br"> </th> +<th class="br"> </th> +<th class="center padl1 padr1">h.</th> +<th class="br"> </th> +<th class="center padl1 padr1">oz.</th> +<th colspan="2" class="center padl1 padr1 br">dr.</th> +<th colspan="2" class="br"> </th> +<th colspan="2" class="center padl1 padr1 br">Feet.</th> +</tr> + +<tr> +<td rowspan="3" class="right padl1 padr1 bl">1</td> +<td rowspan="3" class="right padr0 narrow">-</td> +<td rowspan="3" class="bt bb bl narrow"> </td> +<td rowspan="3" class="br narrow"> </td> +<td class="center padl1 padr1 br">1</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">7</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">3</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr0">1</td> +<td class="center padl1 padr1 br">+</td> +<td class="right padl1 padr0">7</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">Mould</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">7</td> +<td class="br"> </td> +</tr> + +<tr class="thinrow bb"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr class="thinrow"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr> +<td rowspan="3" class="right padl1 padr1 bl">2</td> +<td rowspan="3" class="right padr0">-</td> +<td rowspan="3" class="bt bb bl"> </td> +<td rowspan="3" class="br"> </td> +<td class="center padl1 padr1 br">1</td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr1 br">55</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">3</td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr1 br">55</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">0</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="center padl1 padr1 br">+</td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">Mould</td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr1 br">55</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr class="thinrow bb"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr class="thinrow"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr> +<td rowspan="3" class="right padl1 padr1 bl">3</td> +<td rowspan="3" class="right padr0">-</td> +<td rowspan="3" class="bt bb bl"> </td> +<td rowspan="3" class="br"> </td> +<td class="center padl1 padr1 br">1</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr> +<td class="center padl1 padr1 br">3</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">2</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>8</sub></td> +<td class="right padl1 padr0">8</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +</tr> + +<tr> +<td class="center padl1 padr1 br">Mould</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">0</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr0">9</td> +<td class="br"> </td> +</tr> + +<tr class="thinrow bb"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr class="thinrow"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +<tr> +<td rowspan="2" class="right padl1 padr1 bl">4</td> +<td rowspan="2" class="right padr0">-</td> +<td rowspan="2" class="bt bb bl"> </td> +<td rowspan="2" class="br"> </td> +<td class="center padl1 padr1 br">5</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">5</td> +<td class="br"> </td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br">.18</td> +<td class="right padl1 padr0">8</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +</tr> + +<tr> +<td class="center padl1 padr1 br">Mould</td> +<td class="center padl1 padr1">3</td> +<td class="right padl1 padr1 br">0</td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>8</sub></td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1 br">.</td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +</tr> + +<tr class="thinrow bb"> +<td colspan="4" class="bl br"> </td> +<td class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="3" class="br"> </td> +<td colspan="2" class="br"> </td> +<td colspan="2" class="br"> </td> +</tr> + +</table> + +<p>These experiments, Mr. Walker informs us, +were made in the following manner:—</p> + +<p>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,<span class="pagenum"><a name="Page_30" id="Page_30">[30]</a></span> +and the loss of weight of each candle is contained +in the fourth column.</p> + +<p>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.</p> + +<p>The method which Mr. Walker employed +in comparing one light with another in each +experiment, was that which has been described +<a href="#Page_24">page 24</a>.</p> + +<p>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.</p> + +<p>2. The sign + in the 5th column, signifies<span class="pagenum"><a name="Page_31" id="Page_31">[31]</a></span> +that the candle against which it is placed, gave +a stronger light than the others.</p> + +<p>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.</p> + +<p>For if their quantities of matter be equal, +and times of burning the same, they will give +equal quantities of light, <em class="italic">by the experiments</em>.</p> + +<p>And if the times of burning be equal, the +quantities of light will be directly as their +weights of matter expended.</p> + +<p>Therefore the light is universally in the +compound ratio of the time of burning and +weight of matter consumed.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_32" id="Page_32">[32]</a></span> +of light produced under these circumstances, +be represented by 1.00.</p> + +<p>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.<a name="FNanchor_6" id="FNanchor_6"></a><a href="#Footnote_6" class="fnanchor">[6]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_6" id="Footnote_6"></a><a href="#FNanchor_6"><span class="label">[6]</span></a> To investigate rules for this purpose, 1. Let M represent +the mould candle, <i>a</i> its distance from the wall, on +which the shadows were compared, <i>x</i> its quantity of matter +consumed in a given time, (<i>t</i>) and Q the quantity of light +emitted by M in the same time: 2. Let <i>m</i> represent any +other candle, <i>b</i> its distance from the same wall, and <i>y</i> its +quantity of matter consumed, in the time <i>t</i>.</p> + +<p>Then as the intensities of light are directly as the squares +of the distances of the two candles from the wall, we have as +<i>a</i><sup>2</sup> : Q <span class="symbol">∷</span><span class="symbol_e">::</span> <i>b</i><sup>2</sup> : +<span class="division"><span class="num"><i>b</i><sup class="division">2</sup> + Q</span><span class="denom"><i>a</i><sup class="division">2</sup></span></span> = the quantity of light, emitted by +<i>m</i> in the time.</p> + +<p>Then let us suppose that the quantities of light are directly +as the quantities of matter consumed in the time <i>t</i>, and we +have, As <i>x</i> : Q <span class="symbol">∷</span><span class="symbol_e">::</span> <i>y</i> : <span class="division"><span class="num"><i>y</i> + Q</span><span class="denom"><i>x</i></span></span> = the quantity of light emitted +by <i>m</i> in that time, by hypothesis.</p> + +<p>Now, when <span class="division"><span class="num"><i>b</i><sup class="division">2</sup> + Q</span><span class="denom"><i>a</i><sup class="division">2</sup></span></span> (Theo. 1.) is = <span class="division"><span class="num">Y + Q</span><span class="denom">X</span></span> (Theo. 2.) the +quantities of light of M and <i>m</i> are directly as their quantities +of matter consumed in any given time.</p> + +</div> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_33" id="Page_33">[33]</a></span></p> + +<h4>METHOD<br /> +<span class="fsize60">OF INCREASING</span><br /> +THE LIGHT OF TALLOW CANDLES,<br /> +<span class="fsize60">AND TO OBVIATE THE</span><br /> +NECESSITY OF SNUFFING THEM.</h4> + +<p>Mr. <span class="smcap">Ezekiel Walker</span> 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.</p> + +<p>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<a name="FNanchor_7" id="FNanchor_7"></a><a href="#Footnote_7" class="fnanchor">[7]</a> 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:</p> + +<div class="footnote"> + +<p><a name="Footnote_7" id="Footnote_7"></a><a href="#FNanchor_7"><span class="label">[7]</span></a> 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.</p></div> + +<p><span class="pagenum"><a name="Page_34" id="Page_34">[34]</a></span></p> + +<p>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<a name="FNanchor_8" id="FNanchor_8"></a><a href="#Footnote_8" class="fnanchor">[8]</a>.</p> + +<div class="footnote"> + +<p><a name="Footnote_8" id="Footnote_8"></a><a href="#FNanchor_8"><span class="label">[8]</span></a> The wick’s not being uniformly twisted throughout, +may occasion a little variation in the dimensions of the +flame.</p></div> + +<p>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<span class="pagenum"><a name="Page_35" id="Page_35">[35]</a></span> +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.</p> + +<p>Candles, on which Mr. <span class="smcap">Walker</span> has made +experiments, are described in the following</p> + +<p class="center">TABLE.</p> + +<table class="nowrap" summary="Table page 35"> + +<tr class="bt bb"> +<th class="center padl1 padr1 bl br">No.</th> +<th class="center padl1 padr1 br">No. of<br />candles<br />to the<br />pound<br />avoir-<br />dupoise<br />weight.</th> +<th colspan="2" class="center padl1 padr1 br">Length<br />in<br />inches.</th> +<th class="center padl1 padr1 br">No. of<br />single<br />threads<br />of fine<br />cotton<br />in the wick.</th> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">1</td> +<td class="right padl1 padr3 br">14</td> +<td class="right padl1 padr0">8.</td> +<td class="left padl0 padr1 br">5</td> +<td class="center padl1 padr1 br">10</td> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">2</td> +<td class="right padl1 padr3 br">13</td> +<td class="right padl1 padr0">9.</td> +<td class="br"> </td> +<td class="center padl1 padr1 br">12</td> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">3</td> +<td class="right padl1 padr3 br">10</td> +<td class="right padl1 padr0">9.</td> +<td class="left padl0 padr1 br">74</td> +<td class="center padl1 padr1 br">14</td> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">4</td> +<td class="right padl1 padr3 br">8</td> +<td class="right padl1 padr0">10.</td> +<td class="br"> </td> +<td class="center padl1 padr1 br">20</td> +</tr> + +<tr> +<td class="center padl1 padr1 bl br">5</td> +<td class="right padl1 padr3 br">6</td> +<td class="right padl1 padr0">10.</td> +<td class="left padl0 padr1 br">25</td> +<td class="center padl1 padr1 br">24</td> +</tr> + +<tr class="bb"> +<td class="center padl1 padr1 bl br">Mould</td> +<td class="right padl1 padr3 br">6</td> +<td class="right padl1 padr0">13.</td> +<td class="br"> </td> +<td class="br"> </td> +</tr> + +</table> + +<p>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.</p> + +<p>No. 4, placed at the angle mentioned above, +and lighted, requires no snuffing: it gives a<span class="pagenum"><a name="Page_36" id="Page_36">[36]</a></span> +light very little stronger than No. 1, but its +colour is not quite so white, nor its flame so +steady.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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,<span class="pagenum"><a name="Page_37" id="Page_37">[37]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_38" id="Page_38">[38]</a></span> +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.</p> + +<p>Mr. <span class="smcap">Walker</span> 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.</p> + +<p>The following observations on this subject +are copied from the Monthly Magazine, 1805, +p. 206.</p> + +<p>“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.</p> + +<p><span class="pagenum"><a name="Page_39" id="Page_39">[39]</a></span></p> + +<p>“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.</p> + +<p>“But I found an obstacle to the adoption of +Mr. <span class="smcap">Walker</span>’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.</p> + +<p>“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<span class="pagenum"><a name="Page_40" id="Page_40">[40]</a></span> +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.</p> + +<p>“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<span class="pagenum"><a name="Page_41" id="Page_41">[41]</a></span> +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.</p> + +<p>“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.”</p> + +<p>Lord <span class="smcap">Stanhope</span><a name="FNanchor_9" id="FNanchor_9"></a><a href="#Footnote_9" class="fnanchor">[9]</a> 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<span class="pagenum"><a name="Page_42" id="Page_42">[42]</a></span> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_9" id="Footnote_9"></a><a href="#FNanchor_9"><span class="label">[9]</span></a> Repository of Arts, Vol. I, p. 86.</p></div> + +<p>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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_43" id="Page_43">[43]</a></span></p> + +<p>A taper lamp, with eight threads of cotton, +will consume in one hour <sup>225</sup>⁄<sub>1000</sub> oz. of spermaceti +oil: at six shillings per gallon, the expence of +burning twelve hours is 13.71 farthings.</p> + +<p>At seven shillings, it is 15.995 farthings.</p> + +<p>At eight shillings, it is 18.280 farthings.</p> + +<p>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.</p> + +<p>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.</p> + +<p>At eight shillings, it is 8.022 farthings.</p> + +<p>At nine shillings, it is 9.024 farthings.</p> + +<p><span class="pagenum"><a name="Page_44" id="Page_44">[44]</a></span></p> + +<p class="center">TABLE,</p> + +<p class="center">Exhibiting a series of experiments, made with +a view to determine the real and comparative +expence of burning candles of different +sorts and sizes.</p> + +<table class="nowrap esmaller" summary="Table page 44"> + +<tr class="bt"> +<th class="bl br"> </th> +<th colspan="2" class="center padl1 padr1 br bb">Number of<br />candles<br />in one<br />pound.</th> +<th colspan="3" class="center padl1 padr1 br bb">Weight<br />of one<br />candle.</th> +<th colspan="2" class="center padl1 padr1 br bb">Time<br />one<br />candle<br />lasted.</th> +<th colspan="2" class="center padl1 padr1 br bb">The time<br />that<br />one pound<br />will last.</th> +<th colspan="2" class="center padl1 padr1 br bb">The expence in twelve hours<br />when candles are at 12s.<br />per dozen, which also shews<br />the proportion of expence<br />at any price, per dozen.</th> +</tr> + +<tr> +<th class="bl br"> </th> +<th colspan="2" class="br"> </th> +<th class="center padl1 padr1">Oz.</th> +<th colspan="2" class="center padl1 padr1 br">Dr.</th> +<th class="center padl1 padr1">Hr.</th> +<th class="center padl1 padr1 br">Min.</th> +<th class="center padl1 padr1">Hr.</th> +<th class="center padl1 padr1 br">Min.</th> +<th colspan="2" class="center padl1 padr1 br">Farthings and<br />hundredth parts.</th> +</tr> + +<tr> +<td rowspan="4" class="left padl1 padr1 bl br">A small<br />wick.<br />A large<br />wick.</td> +<td class="right padl1 padr0 bl">18</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">14</td> +<td class="br"> </td> +<td class="right padl1 padr1">3</td> +<td class="right padl1 padr2 br">15</td> +<td class="right padl1 padr1">59</td> +<td class="right padl1 padr2 br">26</td> +<td class="right padl1 padr0">9</td> +<td class="left padl0 padr1 br">.70</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">19</td> +<td class="br"> </td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">13</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">2</td> +<td class="right padl1 padr2 br">40</td> +<td class="right padl1 padr1">50</td> +<td class="right padl1 padr2 br">34</td> +<td class="right padl1 padr0">11</td> +<td class="left padl0 padr1 br">.40</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">16</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">0</td> +<td class="right padl1 padr0">15</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">2</td> +<td class="right padl1 padr2 br">40</td> +<td class="right padl1 padr1">44</td> +<td class="right padl1 padr2 br">2</td> +<td class="right padl1 padr0">13</td> +<td class="left padl0 padr1 br">.08</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">12</td> +<td class="br"> </td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">5</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr1">3</td> +<td class="right padl1 padr2 br">27</td> +<td class="right padl1 padr1">41</td> +<td class="right padl1 padr2 br">24</td> +<td class="right padl1 padr0">13</td> +<td class="left padl0 padr1 br">.92</td> +</tr> + +<tr> +<td rowspan="6" class="bl br"> </td> +<td class="right padl1 padr0 bl">10</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="center padl1 padr1">1</td> +<td class="right padl1 padr0">8</td> +<td class="br"> </td> +<td class="right padl1 padr1">3</td> +<td class="right padl1 padr2 br">36</td> +<td class="right padl1 padr1">38</td> +<td class="right padl1 padr2 br">24</td> +<td class="right padl1 padr0">15</td> +<td class="left padl0 padr1 br">.00</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">7</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr1">4</td> +<td class="right padl1 padr2 br">9</td> +<td class="right padl1 padr1">32</td> +<td class="right padl1 padr2 br">12</td> +<td class="right padl1 padr0">17</td> +<td class="left padl0 padr1 br">.88</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">8</td> +<td class="br"> </td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr0">0</td> +<td class="br"> </td> +<td class="right padl1 padr1">4</td> +<td class="right padl1 padr2 br">15</td> +<td class="right padl1 padr1">34</td> +<td class="right padl1 padr2 br">0</td> +<td class="right padl1 padr0">16</td> +<td class="left padl0 padr1 br">.94</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">5</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr0">13</td> +<td class="br"> </td> +<td class="right padl1 padr1">5</td> +<td class="right padl1 padr2 br">19</td> +<td class="right padl1 padr1">30</td> +<td class="right padl1 padr2 br">15</td> +<td class="right padl1 padr0">19</td> +<td class="left padl0 padr1 br">.06</td> +</tr> + +<tr> +<td rowspan="2" colspan="2" class="center padl1 padr1 br">Mould<br />candles.</td> +<td colspan="3" class="br"> </td> +<td rowspan="2" colspan="2" class="br"> </td> +<td rowspan="2" colspan="2" class="br"> </td> +<td rowspan="2" colspan="2" class="center padl1 padr1 br">Moulds at 14d.<br />per dozen.</td> +</tr> + +<tr> +<td colspan="3" class="center padl1 padr1 br">Each.</td> +</tr> + +<tr> +<td rowspan="3" class="left padl1 padr1 bl br">With<br />wax’d<br />wick.</td> +<td class="right padl1 padr0 bl">3</td> +<td class="left padl0 padr1 br"><sup>7</sup>⁄<sub>8</sub></td> +<td class="center padl1 padr1">2</td> +<td class="right padl1 padr0">12</td> +<td class="br"> </td> +<td class="right padl1 padr1">7</td> +<td class="right padl1 padr2 br">20</td> +<td class="right padl1 padr1">42</td> +<td class="right padl1 padr2 br">39</td> +<td class="right padl1 padr0">15</td> +<td class="left padl0 padr1 br">.74</td> +</tr> + +<tr> +<td class="right padl1 padr0 bl">4</td> +<td class="br"> </td> +<td class="center padl1 padr1">4</td> +<td class="right padl1 padr0">0</td> +<td class="br"> </td> +<td class="right padl1 padr1">9</td> +<td class="right padl1 padr2 br">3</td> +<td class="right padl1 padr1">36</td> +<td class="right padl1 padr2 br">20</td> +<td class="right padl1 padr0">18</td> +<td class="left padl0 padr1 br">.56</td> +</tr> + +<tr class="bb"> +<td class="right padl1 padr0 bl">3</td> +<td class="br"> </td> +<td class="center padl1 padr1">5</td> +<td class="right padl1 padr0">2</td> +<td class="left padl0 padr1 br"><sup>3</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr1">17</td> +<td class="right padl1 padr2 br">30</td> +<td class="right padl1 padr1">52</td> +<td class="right padl1 padr2 br">30</td> +<td class="right padl1 padr0">16</td> +<td class="left padl0 padr1 br">.825</td> +</tr> + +</table> + +<p>The time each candle lasted, was taken from +an average of several trials on each size.</p> + +<p>It has been suggested by Dr. <span class="smcap">Franklin</span>, that +the flame of two candles joined, gives a much +stronger light than both of them separately. +The same, has been observed by Mr. <span class="smcap">Warren</span>, +to be the case with flames of gas-lights, which,<span class="pagenum"><a name="Page_45" id="Page_45">[45]</a></span> +when combined, give a much stronger light +than they would afford, when in a separate +state.</p> + +<p>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.</p> + +<hr class="chap" /> + +<p><span class="pagenum"><a name="Page_46" id="Page_46">[46-<br />47]</a><br /><a name="Page_47" id="Page_47"></a></span></p> + +<h2>PART II.</h2> + +<hr class="sect" /> + +<h3>GAS-LIGHT.</h3> + +<hr class="sect" /> + +<h4>PRELIMINARY OBSERVATION.</h4> + +<p>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 <em class="italic">gas-light</em>.</p> + +<p>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 “<em class="italic">Gas Light and Coke Company</em>,” +to apply this new art of procuring light, by<span class="pagenum"><a name="Page_48" id="Page_48">[48]</a></span> +way of experiment, on a large scale, in lighting +the streets of the metropolis.<a name="FNanchor_10" id="FNanchor_10"></a><a href="#Footnote_10" class="fnanchor">[10]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_10" id="Footnote_10"></a><a href="#FNanchor_10"><span class="label">[10]</span></a> 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.</p></div> + +<p>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<i>l.</i> and His Majesty has the power +of declaring the gas-light charter void, if the +company fail to fulfil the terms of it.</p> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_49" id="Page_49">[49]</a></span></p> + +<h3>THEORY<br /> +<span class="fsize60">OF</span><br /> +THE COMBUSTION OF COAL<br /> +<span class="fsize60">IN<br /> +ELUCIDATION OF THE NATURE AND PRODUCTION<br /> +OF</span><br /> +GAS LIGHT.</h3> + +<p>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<span class="pagenum"><a name="Page_50" id="Page_50">[50]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_51" id="Page_51">[51]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_52" id="Page_52">[52]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_53" id="Page_53">[53]</a></span> +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 <a href="#Page_15">page 15</a>.</p> + +<p>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 <a href="#Page_15">p. 15</a>. 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<span class="pagenum"><a name="Page_54" id="Page_54">[54]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_55" id="Page_55">[55]</a></span> +shape, at an expence out of all proportion below +the value of the products.</p> + +<hr class="sect" /> + +<h3>SKETCH<br /> +<span class="fsize60">OF</span><br /> +THE RISE AND PROGRESS<br /> +<span class="fsize60">OF THE</span><br /> +DISCOVERY AND APPLICATION<br /> +<span class="fsize60">OF</span><br /> +COAL-GAS,<br /> +<span class="fsize60">AS A SUBSTITUTE FOR PROCURING</span><br /> +ARTIFICIAL LIGHT.</h3> + +<p>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.</p> + +<p>In the Philosophical Transactions of the<span class="pagenum"><a name="Page_56" id="Page_56">[56]</a></span> +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.</p> + +<p>It is further known, that in the beginning of +the last century, Dr. Hales<a name="FNanchor_11" id="FNanchor_11"></a><a href="#Footnote_11" class="fnanchor">[11]</a> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_11" id="Footnote_11"></a><a href="#FNanchor_11"><span class="label">[11]</span></a> Vegetab. Statics, vol. I.</p></div> + +<p>In the year 1767, the Bishop of Llandaff<a name="FNanchor_12" id="FNanchor_12"></a><a href="#Footnote_12" class="fnanchor">[12]</a> +examined the nature of the vapour and gazeous +products evolved during the distillation of pit-coal. +This learned philosopher noticed, that<span class="pagenum"><a name="Page_57" id="Page_57">[57]</a></span> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_12" id="Footnote_12"></a><a href="#FNanchor_12"><span class="label">[12]</span></a> Watson’s Chemical Essays, vol. II.</p></div> + +<p>The first discovery and application of the +use of coal-gas for the purpose of illumination is +claimed by Mr. Murdoch.</p> + +<p>Dr. W. Henry of Manchester, has published +the following account<a name="FNanchor_13" id="FNanchor_13"></a><a href="#Footnote_13" class="fnanchor">[13]</a> of this discovery.</p> + +<div class="footnote"> + +<p><a name="Footnote_13" id="Footnote_13"></a><a href="#FNanchor_13"><span class="label">[13]</span></a> Thompson’s System of Chemistry, vol. I. p. 52.</p></div> + +<p>“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<span class="pagenum"><a name="Page_58" id="Page_58">[58]</a></span> +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.</p> + +<p><span class="pagenum"><a name="Page_59" id="Page_59">[59]</a></span></p> + +<p>“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.”</p> + +<p>In the year 1803 and 1804, Mr. Winsor +exhibited at the Lyceum in London the general<span class="pagenum"><a name="Page_60" id="Page_60">[60]</a></span> +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.</p> + +<p>Mr. <span class="smcap">Winsor</span>’s display of gas-lights took +place more than two years before Mr. <span class="smcap">Murdoch</span>’s +priority of right was heard of.</p> + +<p>In stating these facts I do not mean to say +that Mr. <span class="smcap">Murdoch</span> derived the hint of applying +the coal-gas from the previous exhibition +of Mr. <span class="smcap">Winsor</span>, because it is quite within +the bounds of probability that the ideas of Mr.<span class="pagenum"><a name="Page_61" id="Page_61">[61]</a></span> +<span class="smcap">Murdoch</span> may have arisen totally independent +of all acquaintance with Mr. <span class="smcap">Winsor</span>’s.</p> + +<p>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. <span class="smcap">Winsor</span> 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.<span class="pagenum"><a name="Page_62" id="Page_62">[62]</a></span> +<span class="smcap">Winsor</span>’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.</p> + +<p>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.</p> + +<p>On the 18th of May, 1804, Mr. <span class="smcap">Frederick +Albert Winsor</span>, 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.</p> + +<p>In the year 1805, Mr. <span class="smcap">Northern</span>, of Leeds,<span class="pagenum"><a name="Page_63" id="Page_63">[63]</a></span> +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.</p> + +<p>“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.</p> + +<p>“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<span class="pagenum"><a name="Page_64" id="Page_64">[64]</a></span> +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.</p> + +<p>“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.”</p> + +<p>Soon afterwards, Mr. <span class="smcap">Samuel Clegg</span><a name="FNanchor_14" id="FNanchor_14"></a><a href="#Footnote_14" class="fnanchor">[14]</a> of +Manchester, Engineer, communicated an account +of his method of lighting up manufactories<span class="pagenum"><a name="Page_65" id="Page_65">[65]</a></span> +with gas-light to the Society of Arts, +for which he received the silver medal.</p> + +<div class="footnote"> + +<p><a name="Footnote_14" id="Footnote_14"></a><a href="#FNanchor_14"><span class="label">[14]</span></a> This gentleman is at present engineer to the Gas-Light +Company.</p></div> + +<p>Since that time, the application of gas-light +has spread rapidly, and numerous manufactories +and other establishments have been +lighted by coal-gas.</p> + +<p>In France, the application of gas-lights to +economical purposes, was pointed out long +before it was publicly introduced into this +country. M. <span class="smcap">Le Bon</span> 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 <em class="italic">brevet +d’invention</em> (patent) granted to him by the +French government, for the art of producing +light from wood, ignited in close vessels.</p> + +<p>Many other attempts have been made to +derive advantage from the different ingredients +of coal; but they are too obscure to +merit particular enumeration.</p> + +<p>In the year 1808, Mr. <span class="smcap">Murdoch</span> presented +to the Royal Society his account of the application +of gas-light, and was complimented +with Count <span class="smcap">Romford</span>’s medal for the same.</p> + +<p><span class="pagenum"><a name="Page_66" id="Page_66">[66]</a></span></p> + +<p>The following statement is taken from Mr. +<span class="smcap">Murdoch</span>’s paper.</p> + +<p>“The whole of the rooms of the cotton mill +of Mr. <span class="smcap">Lee</span>, 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. <span class="smcap">Lee</span>, +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, (<em class="italic">see <a href="#Page_23">page 23</a></em>) 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.</p> + +<p>“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.</p> + +<p><span class="pagenum"><a name="Page_67" id="Page_67">[67]</a></span></p> + +<p>“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.</p> + +<p>“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<span class="pagenum"><a name="Page_68" id="Page_68">[68]</a></span> +cannel-coal is required in the retort. The price +of the best Wiggan cannel-coal (the sort used) +is 13<sup>1</sup>⁄<sub>2</sub><i>d.</i> per cwt. (22<i>s.</i> 6<i>d.</i> 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<i>l.</i></p> + +<p>“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<i>l.</i></p> + +<p>“The 110 tons of cannel-coal, when distilled, +produce about 70 tons of good coke, which is +sold upon the spot at 1<i>s.</i> 4<i>d.</i> per cwt. and will +therefore amount annually to the sum of 93<i>l.</i></p> + +<p>“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.</p> + +<p>“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. <span class="smcap">Lee</span> at about +550<i>l.</i> per annum, in which some allowance is<span class="pagenum"><a name="Page_69" id="Page_69">[69]</a></span> +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.</p> + +<p>“Mr. <span class="smcap">Lee</span> 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.</p> + +<p>“The economical statement for one year, +then, stands thus:</p> + +<table summary="Table page 69"> + +<tr> +<td class="left top padr3">Cost of 110 tons of cannel coal</td> +<td class="right bot">£ 125</td> +</tr> + +<tr> +<td class="left top padr3">Ditto of 40 tons of common ditto, to carbonise</td> +<td class="right bot bb">20</td> +</tr> + +<tr> +<td class="left top padr3">In all</td> +<td class="right bot bb">145</td> +</tr> + +<tr> +<td class="left top padr3">Deduct the value of 70 tons of coke</td> +<td class="right bot">93</td> +</tr> + +<tr> +<td class="left top padr3">The annual expenditure in coal, after deducting the value of the coke, and without allowing any thing for the tar, is therefore</td> +<td class="right bot">52</td> +</tr> + +<tr> +<td class="left top padr3">And the interest of capital sunk, and wear and tear of apparatus</td> +<td class="right bot">550</td> +</tr> + +<tr> +<td class="left top padr3">Making the total expence of the gas apparatus per annum, about</td> +<td class="right bot">600</td> +</tr> + +</table> + +<p>“That of candles, to give the same light,<span class="pagenum"><a name="Page_70" id="Page_70">[70]</a></span> +would be about 2000<i>l.</i> 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.</p> + +<p>“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<i>l.</i> while that of the tallow would be +3000<i>l.</i>”</p> + +<p>Mr. <span class="smcap">Ackerman</span> 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. <span class="smcap">Ackerman</span>’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:</p> + +<p><span class="pagenum"><a name="Page_71" id="Page_71">[71]</a></span></p> + +<blockquote> + +<p class="center">To <span class="smcap">Mr.</span> ACCUM.</p> + +<p><span class="smcap">Sir</span>,</p> + +<p>“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.</p> + +<p>Now 365 retorts containing 120lb. of coal each, make 43800lb. +which is equal to ten chaldrons of Newcastle and eight tons of +cannel coal.</p> + +<table summary="Table page 71"> + +<tr> +<td class="right top padr1" style="width: 1em;">10</td> +<td colspan="3" class="left top padr3">chaldrons of Newcastle coals, at 65s. make</td> +<td class="right bot padl1 padr1">£ 32</td> +<td class="right bot padl1 padr1">10</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="right top padr1">8</td> +<td colspan="3" class="left top padr3">tons of cannel coal,<a name="FNanchor_15" id="FNanchor_15"></a><a href="#Footnote_15" class="fnanchor">[15]</a> (this coal is sold by weight) at 100s. per ton</td> +<td class="right bot padl1 padr1">40</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="right top padr1">7</td> +<td colspan="3" class="left top padr3">chaldrons of common coals for carbonising, at 55s.</td> +<td class="right bot padl1 padr1">19</td> +<td class="right bot padl1 padr1">5</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="4" class="left top padr3">To wages paid the servant for attending the gas apparatus</td> +<td class="right bot padl1 padr1">30</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="4" class="left top padr3">Interest of money sunk</td> +<td class="right bot padl1 padr1">30</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td> </td> +<td colspan="3" class="left top padr3">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.</td> +<td colspan="3" class="bb"> </td> +</tr> + +<tr> +<td colspan="4" class="right top padr3">Total expence of the gas lights</td> +<td class="right bot padl1 padr1">151</td> +<td class="right bot padl1 padr1">15</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="7" class="center top blankabove blankbelow">DEDUCT</td> +</tr> + +<tr> +<td class="right top padr1">23</td> +<td class="left top padr3">chaldrons of coke, at 60s. per chaldron</td> +<td class="right bot padl1 padr1">69</td> +<td colspan="4"> </td> +</tr> + +<tr> +<td colspan="2" class="left top padr3">Ammoniacal liquor</td> +<td class="right bot padl1 padr1">5</td> +<td colspan="4"> </td> +</tr> + +<tr> +<td colspan="2" class="left top padr3">Tar</td> +<td class="right bot padl1 padr1">6</td> +<td colspan="4"> </td> +</tr> + +<tr> +<td colspan="2" class="left top padr3">Charcoal employed by the copper-plate printers to heat their plates, which is now done with the gas-light flame, cost, annually</td> +<td class="right bot padl1 padr1">25</td> +<td colspan="4"> </td> +</tr> + +<tr> +<td colspan="2" class="left top padr3">Two chaldrons of coals <em class="italic">minus</em> used as fuel, for warming the house, since the adoption of the gas-lights, at 65s. per chaldron</td> +<td class="right bot padl1 padr1 bb">6</td> +<td class="right bot padl1 padr1 bb">10</td> +<td colspan="3"> </td> +</tr> + +<tr> +<td colspan="4"> </td> +<td class="right bot padl1 padr1 bb">111</td> +<td class="right bot padl1 padr1 bb">10</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td colspan="4" class="right top padr3">Nett expences of the gas-lights</td> +<td class="right bot padl1 padr1 bb">£ 40</td> +<td class="right bot padl1 padr1 bb">5</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td colspan="4" class="left top padr3">The lights used in my Establishment, prior to the gas-lights, amounted annually to</td> +<td class="right bot padl1 padr1">160</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="4" class="left top padr3">My present system of lighting with gas costs, per ann.</td> +<td class="right bot padl1 padr1 bb">40</td> +<td class="right bot padl1 padr1 bb">5</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td colspan="4" class="right top padr3">Balance in favor of the gas for one year</td> +<td class="right bot padl1 padr1">£ 119</td> +<td class="right bot padl1 padr1">15</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +</table> + +</blockquote> + +<div class="footnote"> + +<p><a name="Footnote_15" id="Footnote_15"></a><a href="#FNanchor_15"><span class="label">[15]</span></a> <em class="italic">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.</em></p></div> + +<p><span class="pagenum"><a name="Page_72" id="Page_72">[72]</a></span></p> + +<blockquote> + +<p>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.</p> + +<p class="center">I am, with respect,<br /> +Yours,</p> + +<p class="placedate">Strand, March 13,<br /> +1815.</p> + +<p class="signature">R. ACKERMAN.”</p> + +</blockquote> + +<p>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. +<span class="smcap">Cook</span>, 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 <em class="italic">naïveté</em> in his own +account of the process which will amuse as well +as instruct the reader.</p> + +<p>“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<span class="pagenum"><a name="Page_73" id="Page_73">[73]</a></span> +make perhaps six hundred gallons<a name="FNanchor_16" id="FNanchor_16"></a><a href="#Footnote_16" class="fnanchor">[16]</a> 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.”</p> + +<div class="footnote"> + +<p><a name="Footnote_16" id="Footnote_16"></a><a href="#FNanchor_16"><span class="label">[16]</span></a> A wine-gallon is equal to 231 cubic inches.</p></div> + +<p>Thus are the candles which Mr. <span class="smcap">Cook</span> 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<i>l.</i> 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<span class="pagenum"><a name="Page_74" id="Page_74">[74]</a></span> +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. <span class="smcap">Cook</span>’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<i>l.</i> out of the 50<i>l.</i> 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. <span class="smcap">Cook</span> assures us, “will still be considerable:<span class="pagenum"><a name="Page_75" id="Page_75">[75]</a></span> +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<i>l.</i> or 12<i>l.</i> which he will nearly, if not +quite, save the first year.”</p> + +<p>Mr. <span class="smcap">Ackerman</span> 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. +<span class="smcap">Lloyd</span>, of Queen Street, Southwark, thimble +manufacturers and whitesmiths, who have used +the gas-light for soldering and other purposes +these five years past.</p> + +<table summary="Table page 75-76"> + +<tr> +<td class="left top padr3">From 4 pecks or 1 bushel of coals, weighing 69lbs. for which we now pay (1809) 1s. we produce 4<sup>3</sup>⁄<sub>4</sub> pecks of coke and <sup>1</sup>⁄<sub>2</sub> peck of coal not carbonised remains in the distilling pot, which together with the coke weighs 58lbs. 6 oz. value at 1s. per bushel</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">1</td> +<td class="right bot padl1 padr1">4</td> +</tr> + +<tr> +<td class="left top padr3">we procure 6lbs. 4 oz. of tar which<span class="pagenum"><a name="Page_76" id="Page_76">[76]</a></span> we use as pith—it saves us</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">1</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td> </td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">2</td> +<td class="right bot padl1 padr1">4</td> +</tr> + +<tr> +<td class="center top">Deduct for coal</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">1</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td class="left top padr3">Profit on coke and tar</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">1</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td class="left top padr3">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</td> +<td class="right bot padl1 padr1">0</td> +<td class="right bot padl1 padr1">7</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">To this, add profits on coke and tar</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">1</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td class="left top padr3">Gained out of every bushel of coal</td> +<td class="right bot padl1 padr1 bb">0</td> +<td class="right bot padl1 padr1 bb">8</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +</table> + +<p>“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.”</p> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_77" id="Page_77">[77]</a></span></p> + +<h3>THEORY<br /> +<span class="fsize60">OF</span><br /> +THE PRODUCTION OF GAS-LIGHT,<br /> +<span class="fsize60">AND</span><br /> +DESCRIPTION<br /> +<span class="fsize60">OF</span><br /> +A PORTABLE APPARATUS<br /> +<span class="fsize60">FOR EXHIBITING, IN THE SMALL WAY, THE GENERAL<br /> +NATURE OF THIS SPECIES OF LIGHT.</span></h3> + +<p>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<span class="pagenum"><a name="Page_78" id="Page_78">[78]</a></span> +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<span class="pagenum"><a name="Page_79" id="Page_79">[79]</a></span> +which the gas alone can issue, thus forming +small distinct streams of light.</p> + +<div class="figcenter"><a name="Plate2" id="Plate2"></a> +<img src="images/illo093.jpg" alt="Gas-apparatus" width="600" height="383" /> +<p class="largeimg"><a href="images/lg093.jpg">Larger image</a> (279 kB)</p> +</div> + +<p>The gas-apparatus, <a href="#Plate2">plate 2</a>, 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.</p> + +<p>It consists of three distinct apparatus:—namely, +a portable furnace, <a href="#Plate2">fig. 1, plate 2</a>, by +means of which the gas is prepared—<a href="#Plate2">fig. 2</a>, 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—<a href="#Plate2">fig. +3</a>, 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:—<i>a</i>, +represents a cast iron retort, such as +is used for chemical operations in the small<span class="pagenum"><a name="Page_80" id="Page_80">[80]</a></span> +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. <i>b.</i> is a metal pipe which conveys +all the distillatory products from the retort into +the purifier <a href="#Plate2">fig. 2</a>. This tube is bent at right +angles at the extremity where it enters the intermediate +vessel <a href="#Plate2">fig. 2</a>. The purifier <a href="#Plate2">fig. 2</a>, is +divided into three compartments marked <i>c.</i> <i>d.</i> <i>e.</i> +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, <i>d</i>, 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<span class="pagenum"><a name="Page_81" id="Page_81">[81]</a></span> +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 <i>e</i> is left empty +to receive the tar and other liquid products. +Into the first compartment <i>c</i>, all the gazeous +and liquid products are delivered, as they +become evolved during the distillation, by +means of the pipe <i>b</i>. The compartment <i>d</i>, 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 <i>b</i>, to pass readily +through it. From the chamber <i>c</i>, the liquid +and gazeous products pass to the tar-chamber, +or compartment <i>e</i>, by means of the descending +pipe <i>f</i>. The tar and other condensible substances +are therefore deposited at <i>e</i>, whilst the +gazeous products alone ascend from the tar-chamber +<i>e</i>, by the pipe <i>g</i>, and down again +the pipe <i>h</i>, (which is closed at the top) into +the compartment <i>d</i>, of the vessel or purifier, +<a href="#Plate2">fig. 2</a>. The gas being thus made to pass from +the compartment <i>e</i>, up into the pipe <i>g</i>, and +down the pipe <i>h</i>, (which is closed at the top) +into the purifier <i>d</i>, is brought into contact with<span class="pagenum"><a name="Page_82" id="Page_82">[82]</a></span> +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 <i>c</i>, 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>i</i> +is another wide-mouth funnel, by +means of which the chamber <i>d</i>, 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 <i>d</i>, of the +purifier, forming carbonate and hidro-sulphuret +of lime. The carburetted hidrogen, being +left more or less pure, is conveyed through the +pipe <i>k</i>, into the gasometer, <a href="#Plate2">fig. 3</a>. The communication +of the purifier, <a href="#Plate2">fig. 2</a>, with the gasometer, +is made by means of the well-known +water-valve <i>l</i>, placed so that the communicating +tube <i>k</i>, may be easily removed at pleasure—<i>m</i>, +is a cock for drawing off the tar, &c. +<i>n</i>, a gauge-cock for ascertaining the height of<span class="pagenum"><a name="Page_83" id="Page_83">[83]</a></span> +the liquid in the chamber <i>d</i>. The gasometer, +<a href="#Plate2">fig. 3</a>, 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. <i>o</i> is a +pipe, which communicates with the water-valve +<i>l</i>, and by means of which the gas passes +from the purifier, <a href="#Plate2">fig. 2</a>, into the gasometer. +The upper end of this pipe is covered, in the +manner of a hood, by a cylindrical vessel <i>p</i>, +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 <i>p</i>, 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<span class="pagenum"><a name="Page_84" id="Page_84">[84]</a></span> +the gasometer, which is suspended to move up +and down by the chains, pullies, and balance-weights, +<i>q</i>. From the centre of the gasometer +a tube, <i>r</i>, descends, which includes a pipe, <i>s</i>, +fixed perpendicular from the bottom of the +cistern. The fixed pipe <i>r</i>, forms a guide to +keep the gasometer always perpendicular. <i>t</i> is +also an iron pipe made fast in the centre of the +inner vessel, and communicates with the upright +tube, <i>s</i>, in the outer vessel. This contrivance +obliges the gas to pass into the pipe <i>t</i>, +whilst it also serves to keep the gasometer +steady when nearly out of the outer cistern.</p> + +<p>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 <i>q</i> <i>q</i>, 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 <i>o</i>, into +the vessel, <i>p</i>, from which it displaces the +water, and passes out at the small holes, as<span class="pagenum"><a name="Page_85" id="Page_85">[85]</a></span> +before described, rising through the water into +the gasometer, and raising it up: the gas then +passes away to the burners, <i>u</i> <i>u</i>. 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. <i>v</i> <i>v</i> are cocks to let off any +liquid that may collect in the pipe <i>o</i> or <i>t</i>; 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, <em class="italic">dance</em>, or become extinguished. +<i>x</i> is the main stop-cock which communicates +with the burners—these, of course, may be +placed as convenience may require. <i>z</i> <i>z</i> are +two projecting parts in the top of the gasometer;<span class="pagenum"><a name="Page_86" id="Page_86">[86]</a></span> +they are intended to receive the hood <i>p</i>, +and the upper extremity of the pipe <i>t</i>, 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.</p> + +<p>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<span class="pagenum"><a name="Page_87" id="Page_87">[87]</a></span> +of the size of the flames; which could +not be rendered uniform.</p> + +<p>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.</p> + +<p>To compensate for this increasing weight of +the gasometer, and render a scale of equal +graduations accurate, some have ingeniously<span class="pagenum"><a name="Page_88" id="Page_88">[88]</a></span> +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.</p> + +<p>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.</p> + +<p>Pit-coal is not the only substance which affords +carburetted hydrogen; this gazeous fluid<span class="pagenum"><a name="Page_89" id="Page_89">[89]</a></span> +may be obtained in a great variety of ways, +and with very considerable differences in specific +gravity and proportion of ingredients.</p> + +<p>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.</p> + +<p>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 <em class="italic">ignis fatuus</em> 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.</p> + +<p>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<span class="pagenum"><a name="Page_90" id="Page_90">[90]</a></span> +into the bottle; when by thus stirring the mud +in various places, the air may be catched in the +bottle.</p> + +<p>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.</p> + +<p>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 +(<span class="smcap">Van Dieman</span>, <span class="smcap">Troostwyck</span>, 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.<span class="pagenum"><a name="Page_91" id="Page_91">[91]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_92" id="Page_92">[92]</a></span> +air as 2 to 3—112lb. of common cannel coal produce +at its <em class="italic">minimum</em>, 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) <span class="division"><span class="num">7000</span><span class="denom">175</span></span> = 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,<span class="pagenum"><a name="Page_93" id="Page_93">[93]</a></span> +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 <em class="italic">minimum</em>, +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 <span class="division"><span class="num">350</span><span class="denom">20</span></span> = +17<sup>1</sup>⁄<sub>2</sub>lbs. 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.</p> + +<p>With regard to Newcastle coals<a name="FNanchor_17" id="FNanchor_17"></a><a href="#Footnote_17" class="fnanchor">[17]</a>, 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_17" id="Footnote_17"></a><a href="#FNanchor_17"><span class="label">[17]</span></a> One chaldron of Newcastle coal weighs from 2850 to +upwards of 2978lb.</p></div> + +<p>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<span class="pagenum"><a name="Page_94" id="Page_94">[94]</a></span> +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.<a name="FNanchor_18" id="FNanchor_18"></a><a href="#Footnote_18" class="fnanchor">[18]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_18" id="Footnote_18"></a><a href="#FNanchor_18"><span class="label">[18]</span></a> One pound of coal-tar produces 15 cubic feet of carburetted +hidrogen abounding in olifiant gas.</p></div> + +<p>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.</p> + +<p>The retorts best calculated for large gas-light +works are seven or eight foot long (without the +mouth-piece) and twelve inches in diameter,<span class="pagenum"><a name="Page_95" id="Page_95">[95]</a></span> +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;<a name="FNanchor_19" id="FNanchor_19"></a><a href="#Footnote_19" class="fnanchor">[19]</a> 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<span class="pagenum"><a name="Page_96" id="Page_96">[96]</a></span> +an intolerable suffocating odour, when the gas +is burnt which is particularly perceptible in low +rooms illuminated with such gas.</p> + +<div class="footnote"> + +<p><a name="Footnote_19" id="Footnote_19"></a><a href="#FNanchor_19"><span class="label">[19]</span></a> It is chiefly a mixture of carbonic oxid, and hydrogen gas.</p></div> + +<p>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.</p> + +<p>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.</p> + +<p>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. +<sup>1</sup>⁄<sub>27</sub> part of its own bulk of pure coal-gas<span class="pagenum"><a name="Page_97" id="Page_97">[97]</a></span> +is absorbed by the water over which it is confined +in the gazometer.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_98" id="Page_98">[98]</a></span> +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.</p> + +<p>“Messrs. <span class="smcap">Sobolewsky</span> and <span class="smcap">Horrer</span>, 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<span class="pagenum"><a name="Page_99" id="Page_99">[99]</a></span> +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.”<a name="FNanchor_20" id="FNanchor_20"></a><a href="#Footnote_20" class="fnanchor">[20]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_20" id="Footnote_20"></a><a href="#FNanchor_20"><span class="label">[20]</span></a> See Repository of Arts, Vol. XI. No. 36, p. 341.</p></div> + +<hr class="sect" /> + +<h3>UTILITY<br /> +<span class="fsize60">OF THE</span><br /> +GAS-LIGHT ILLUMINATION,<br /> +<span class="fsize60">WITH REGARD TO</span><br /> +PUBLIC AND PRIVATE ECONOMY.</h3> + +<p>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<span class="pagenum"><a name="Page_100" id="Page_100">[100]</a></span> +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<span class="pagenum"><a name="Page_101" id="Page_101">[101]</a></span> +in all our common lights. The products +of the combustion are water and carbonic acid +gas<a name="FNanchor_21" id="FNanchor_21"></a><a href="#Footnote_21" class="fnanchor">[21]</a>. The accurate and elegant experiments +of Dr. W. <span class="smcap">Henry</span> 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<a name="FNanchor_22" id="FNanchor_22"></a><a href="#Footnote_22" class="fnanchor">[22]</a>, which<span class="pagenum"><a name="Page_102" id="Page_102">[102]</a></span> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_21" id="Footnote_21"></a><a href="#FNanchor_21"><span class="label">[21]</span></a> 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.</p></div> + +<div class="footnote"> + +<p><a name="Footnote_22" id="Footnote_22"></a><a href="#FNanchor_22"><span class="label">[22]</span></a> 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. +</p> +<blockquote> + +<p>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. +</p> +<p> +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.” +</p> +<p> +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.” +</p> +<p> +Q. “And you say the same in regard to the use of the gas-lights +in your own family?—A. Certainly I do.”</p></blockquote> +</div> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_103" id="Page_103">[103]</a></span></p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_104" id="Page_104">[104]</a></span> +by the stand or support of the combustible +matter.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_105" id="Page_105">[105]</a></span> +house. When transparencies are wanted as +decorations for halls, lobbies, &c. more than +light, recesses may be filled with different coloured +<em class="italic">media</em>, or paintings, and any intensity of +light may be thrown on the object.</p> + +<p>If a number of minute holes are made in +the end of a gas pipe, it forms as many <i lang="fr" xml:lang="fr">jets +de feu</i>, 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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_106" id="Page_106">[106]</a></span> +night of a general illumination, compared with +the glimmering light of its ordinary parish +lamps.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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,<span class="pagenum"><a name="Page_107" id="Page_107">[107]</a></span> +no doubt will pay all its expences besides the +interest of capital, and leave a surplus of profit.</p> + +<p>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.<a name="FNanchor_23" id="FNanchor_23"></a><a href="#Footnote_23" class="fnanchor">[23]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_23" id="Footnote_23"></a><a href="#FNanchor_23"><span class="label">[23]</span></a> 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. +</p> +<p> +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. +</p> +<p> +In the East end of the metropolis, the gas-light <em class="italic">mains</em> 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.</p></div> + +<p>Enough therefore, has been done to prove the +possibility of lighting houses, and streets, with<span class="pagenum"><a name="Page_108" id="Page_108">[108]</a></span> +gas, which would have been regarded twenty +years ago as an extravagant paradox.<a name="FNanchor_24" id="FNanchor_24"></a><a href="#Footnote_24" class="fnanchor">[24]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_24" id="Footnote_24"></a><a href="#FNanchor_24"><span class="label">[24]</span></a> I am informed by Mr. <span class="smcap">Clegg</span>, 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. +</p> + +<blockquote> + +<p>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. +</p> +<p> +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.</p></blockquote> +</div> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_109" id="Page_109">[109]</a></span></p> + +<p>Another advantageous application of the gas-light +must be the supplying of light-houses.</p> + +<p>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.</p> + +<p>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.</p> + +<p>The ease with which the largest gas-light +flame is instantly extinguished by shutting the<span class="pagenum"><a name="Page_110" id="Page_110">[110]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_111" id="Page_111">[111]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p>The heat produced by gas-lights must be +observed by every one who has had an opportunity<span class="pagenum"><a name="Page_112" id="Page_112">[112]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>From trials made on this subject, I am enabled<span class="pagenum"><a name="Page_113" id="Page_113">[113]</a></span> +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.<a name="FNanchor_25" id="FNanchor_25"></a><a href="#Footnote_25" class="fnanchor">[25]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_25" id="Footnote_25"></a><a href="#FNanchor_25"><span class="label">[25]</span></a> Mr. <span class="smcap">Dalton</span>’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: +</p> +<p> +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. +</p> +<p> +It was thus proved that— +</p> + +<table summary="Table footnote 25"> + +<tr> +<td class="left top padr3">Olefiant gas raises an equal volume of water</td> +<td class="left bot">14°</td> +</tr> + +<tr> +<td class="left top padr3">Carburetted hidrogen, or coal gas</td> +<td class="left bot">10</td> +</tr> + +<tr> +<td class="left top padr3">Carbonic oxid</td> +<td class="left bot">4</td> +</tr> + +<tr> +<td class="left top padr3">Hidrogen</td> +<td class="left bot">5</td> +</tr> + +<tr> +<td class="left top padr3">Spermaceti oil 10 grains burnt in a lamp raised 30,000 grains of water</td> +<td class="left bot">5</td> +</tr> + +<tr> +<td class="left top padr3">Tallow</td> +<td class="left bot">5</td> +</tr> + +<tr> +<td class="left top padr3">Wax</td> +<td class="left bot">5,75</td> +</tr> + +<tr> +<td class="left top padr3">Oil of turpentine</td> +<td class="left bot">3</td> +</tr> + +<tr> +<td class="left top padr3">Spirit of wine</td> +<td class="left bot">2</td> +</tr> + +</table> + +</div> + +<p>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<span class="pagenum"><a name="Page_114" id="Page_114">[114]</a></span> +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.</p> + +<p>The great power of a gas-flame does not +appear when we try small quantities of it, and<span class="pagenum"><a name="Page_115" id="Page_115">[115]</a></span> +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.</p> + +<div class="figcenter"><a name="Plate3" id="Plate3"></a> +<img src="images/illo131.jpg" alt="Gas lamps" width="600" height="367" /> +<p class="largeimg"><a href="images/lg131.jpg">Larger image</a> (252 kB)</p> +</div> + +<p>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.</p> + +<p>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.</p> + +<p><a href="#Plate3"><span class="smcap">Plates</span> III.</a> <a href="#Plate4">IV.</a> and <a href="#Plate5">V.</a> exhibit such designs +of different kinds of gas-lamps, chandeliers, +lustres, candelabras, &c. as are already in use +in this Metropolis.</p> + +<p><a href="#Plate3"><span class="smcap">Plate</span> III. fig. 1</a>, represents a <em class="italic">Rod Lamp</em>. +The gas passes through the rod <i>a</i>, to the Argand +burner, which is surrounded by a cylindrical +chimney, <i>c</i>, swelling out at the lower<span class="pagenum"><a name="Page_116" id="Page_116">[116]</a></span> +extremity. The construction of the Argand +burner we have mentioned already, <a href="#Page_78"><i>p.</i> 78</a>.</p> + +<p>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.</p> + +<p><a href="#Plate3">Fig. 2</a>. <em class="italic">A Rod Gas Lamp, with branches.</em> +The gas passes through the hollow rod, <i>a</i>, and +part of the hollow branch, <i>b</i>, to the burner of +the lamp. The cylindrical shaped glass, <i>c</i>, exhibited +in this figure, is not so well adapted for +the compleat combustion of coal-gas, as the +belly-shaped chimney, <i>c</i>, represented in<span class="pagenum"><a name="Page_117" id="Page_117">[117]</a></span> <a href="#Plate3">fig. 1, +3, 5, 6</a>, 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, +<a href="#Plate3">fig. 1</a>.</p> + +<p><a href="#Plate3">Fig. 3</a>. <em class="italic">A Bracket Lamp.</em> <i>a</i>, the tube +which conveys the gas to the burner; <i>b</i>, the +stop-cock of the tube.</p> + +<p><a href="#Plate3">Fig. 4</a>. <em class="italic">A Pendent Rod Lamp</em>; in which the +gas is supposed to come from a pipe above, +through the ceiling, into the pipe, <i>a</i>, to supply +the burners. The tulip-shaped chimney, <i>b</i>, +of this lamp, is likewise ill adapted for gas-light +burners.</p> + +<p><a href="#Plate3">Fig. 5</a>. <em class="italic">A pendent double-bracket Lamp.</em> +The gas passing through the perpendicular +tube, <i>a</i>, into the brackets, <i>b</i> <i>b</i>; <i>c</i> shows the +Argand burner.</p> + +<p><span class="pagenum"><a name="Page_118" id="Page_118">[118]</a></span></p> + +<p><a href="#Plate3">Fig. 6</a>. <em class="italic">A swing Bracket Lamp.</em> <i>a</i>, the +gas-pipe with its stop-cock; <i>b</i>, a brass ball, +communicating with the pipe, <i>a</i>; <i>c</i>, the conducting +tube, ground air-tight into the ball, +<i>b</i>, and communicating with the burner of the +lamp, so as to allow it to have an horizontal +motion.</p> + +<p><a href="#Plate3">Fig. 7</a>. Shews the construction of the ball +<i>b</i>, and pipe, <i>c</i>, of the lamp, <a href="#Plate3">fig. 6</a>.</p> + +<p><a href="#Plate3">Fig. 8</a>. <em class="italic">A Swing Cockspur Lamp</em>, constructed +upon the same plan as <a href="#Plate3">fig. 6</a>. These two +lamps are very convenient for desks in counting-houses, +&c.</p> + +<p><a href="#Plate3">Fig. 9</a>. 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.</p> + +<p><a href="#Plate3">Fig. 10</a>. Section of the stop-cock, with ball +and socket.</p> + +<p><a href="#Plate3">Fig. 11</a>. Shows the ball and socket, <a href="#Plate3">fig. 9</a>, +in perspective.</p> + +<div class="figcenter"><a name="Plate4" id="Plate4"></a> +<img src="images/illo137.jpg" alt="Gas lamps" width="600" height="343" /> +<p class="largeimg"><a href="images/lg137.jpg">Larger image</a> (205 kB)</p> +</div> + +<p><a href="#Plate4"><span class="smcap">Plate</span> IV</a>,<a name="FNanchor_26" id="FNanchor_26"></a><a href="#Footnote_26" class="fnanchor">[26]</a> <a href="#Plate4">fig. 1</a>. <em class="italic">A Candelabrum</em>; the gas<span class="pagenum"><a name="Page_119" id="Page_119">[119]</a></span> +pipe ascending from the floor of the apartment, +through the column <i>a</i>, and terminating +in the burner of the lamp.</p> + +<div class="footnote"> + +<p><a name="Footnote_26" id="Footnote_26"></a><a href="#FNanchor_26"><span class="label">[26]</span></a> The gas-lamps exhibited in this plate, are employed +in the library, counting-house, warehouse, and offices of +Mr. <span class="smcap">Ackerman</span>, and, by whose permission, they are copied +on this occasion.</p></div> + +<p><a href="#Plate4">Fig. 2</a>. <em class="italic">A fancy pendent Cockspur Lamp.</em> +The gas being transmitted to the burners, <i>c</i> <i>c</i>, +by means of the pipe, <i>a</i>.</p> + +<p><a href="#Plate4">Fig. 3</a>. <em class="italic">A Pedestal Argand Lamp.</em> <i>a</i>, the +pipe and stop-cock, which transmits to, and +shuts off the gas from the burner of the lamp.</p> + +<p><a href="#Plate4">Fig. 4</a>. <em class="italic">A Pedestal Cockspur Lamp.</em> <i>a</i>, the +stop-cock and gas-pipe.</p> + +<p><a href="#Plate4">Fig. 5</a>. <em class="italic">A fancy bracket Cockspur Lamp</em>, +intended merely to show that the coal-gas, as +it passes to the burner, is perfectly devoid of +colour, and invisible. <i>a</i> is a glass vessel furnished +at its orifice with a brass cap, <i>c</i>, and +perforated ball, out of which the gas-flame +proceeds. <i>b</i>, the pipe which conveys the gas +into the glass vessel, <i>a</i>.</p> + +<p><a href="#Plate4">Fig. 6</a>. <em class="italic">A Bracket Argand Lamp.</em> <i>a</i> and <i>b</i>, +the gas pipe communicating with the burner.</p> + +<p><a href="#Plate4">Fig. 7 and 8</a>. <em class="italic">A Horizontal Bracket Lamp.</em> +<i>a</i>, the gas pipe, supposed to be concealed +in the ceiling. <i>b</i>, the communicating pipe, +which, together with <i>c</i>, branches out at right +angles at <i>d</i> <i>d</i>. <i>e</i> <i>e</i>, are the burners of the lamp.</p> + +<div class="figcenter"><a name="Plate5" id="Plate5"></a> +<img src="images/illo140.jpg" alt="Gas lamps" width="600" height="355" /> +<p class="largeimg"><a href="images/lg140.jpg">Larger image</a> (286 kB)</p> +</div> + +<p><span class="pagenum"><a name="Page_120" id="Page_120">[120]</a></span></p> + +<p><a href="#Plate5"><span class="smcap">Plate</span> V</a>. <a href="#Plate5">fig. 1</a>. <em class="italic">A Candelabrum</em>, into which +the gas-pipe ascends from the floor of the +apartment, the lateral branches communicating +with the central tube.</p> + +<p><a href="#Plate5">Fig. 2</a>. <em class="italic">An Arabesque Chandelier.</em> The gas +enters from the ceiling of the room into the +rope-shaped pipe, <i>a</i>, from which it proceeds +through one of the arched ribs, <i>b</i> <i>b</i>, into the +horizontal hoop, or pipe, <i>c</i>.</p> + +<p><a href="#Plate5">Fig. 3</a>. <em class="italic">A Roman Chandelier.</em> The gas enters +through the inflexible hollow chain, <i>a</i>, into +the central tube, <i>b</i>, from whence the burners +are supplied by the lateral branches, <i>c</i> <i>c</i>.</p> + +<p><a href="#Plate5">Fig. 4</a>. <em class="italic">A Gothic Chandelier.</em> The gas is +transmitted to the burners through the rope, <i>a</i>, +which includes a tube, and the communication +with the burners is established through the +lateral branches.</p> + +<p><a href="#Plate5">Fig. 5</a>. <em class="italic">A Pedestal Figure Lamp.</em> The gas is +here made to pass by means of a pipe through +the body of the figure into the lattice-work +<em class="italic">plateau</em>, constructed of hollow and perforated +brass tubes.</p> + +<p><a href="#Plate5">Fig. 6</a>. <em class="italic">A Pedestal Vase Lamp.</em> The gas-tube +enters through one of the claw-feet of the +altar-shaped pedestal, into the glass vase, <i>a</i>, at<span class="pagenum"><a name="Page_121" id="Page_121">[121]</a></span> +the bottom of which it joins the tubes communicating +with the metallic corn-ears, <i>b</i>, at the +upper extremities of which it forms <em class="italic">jets de feu</em>.</p> + +<p><a href="#Plate5">Fig. 7</a>. <em class="italic">A Girandole.</em> The gas enters through +the bracket, <i>a</i>, and is conveyed to the burners +by the descending tubes, <i>b</i> <i>b</i>.</p> + +<p><a href="#Plate5">Fig. 8</a>. <em class="italic">A Candelabrum</em>, having a central +pipe, through which the gas is conducted to +the burner at the top.</p> + +<hr class="sect" /> + +<h4><span class="fsize60">OTHER</span><br /> +PRODUCTS OBTAINABLE FROM COAL:<br /> +<span class="fsize60">NAMELY,</span><br /> +COKE, TAR, ESSENTIAL OIL, &c.</h4> + +<p>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.</p> + +<p><em class="italic">Coke.</em>—The substance called coke, which +constitutes the skeleton of the coal, or its carbonaceous +base, is left behind in the retort, after<span class="pagenum"><a name="Page_122" id="Page_122">[122]</a></span> +all the evaporable products have been expelled +from the coal by heat.—See <a href="#Page_85">page 85</a>.</p> + +<p>It is sufficiently known, that coke is a more +valuable fuel than the coal from which it is +obtained.</p> + +<p>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.<a name="FNanchor_27" id="FNanchor_27"></a><a href="#Footnote_27" class="fnanchor">[27]</a> In the manufacture<span class="pagenum"><a name="Page_123" id="Page_123">[123]</a></span> +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 <em class="italic">ennui</em> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_27" id="Footnote_27"></a><a href="#FNanchor_27"><span class="label">[27]</span></a> 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.</p></div> + +<p>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<span class="pagenum"><a name="Page_124" id="Page_124">[124]</a></span> +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.</p> + +<p>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.</p> + +<p>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 <em class="italic">very intense</em>, 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<span class="pagenum"><a name="Page_125" id="Page_125">[125]</a></span> +the fire, unless the bars of the grate be too +close together.</p> + +<p>The relative effects of heat produced by +coke and coal are as follows:—</p> + +<p>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.<a name="FNanchor_28" id="FNanchor_28"></a><a href="#Footnote_28" class="fnanchor">[28]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_28" id="Footnote_28"></a><a href="#FNanchor_28"><span class="label">[28]</span></a> 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, +</p> +<p> +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.</p></div> + +<p><span class="pagenum"><a name="Page_126" id="Page_126">[126]</a></span></p> + +<p>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.</p> + +<p>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 <em class="italic">third more lime</em> at the <em class="italic">same time</em>.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_127" id="Page_127">[127]</a></span></p> + +<p>The following account given by Mr. Davis,<a name="FNanchor_29" id="FNanchor_29"></a><a href="#Footnote_29" class="fnanchor">[29]</a> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_29" id="Footnote_29"></a><a href="#FNanchor_29"><span class="label">[29]</span></a> Philosophical Magazine, Vol. 33, p. 435.</p></div> + +<p>“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<span class="pagenum"><a name="Page_128" id="Page_128">[128]</a></span> +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.</p> + +<p>“On applying coke instead of coal, the +produce of lime may be increased to nearly 30<span class="pagenum"><a name="Page_129" id="Page_129">[129]</a></span> +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 <em class="italic">less attendance</em> and <em class="italic">less labour</em>, +and the whole saving, thus accomplished, +amounts to more than 50 <em class="italic">per cent. on the +lime-kiln</em>.</p> + +<p>“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.</p> + +<p>“If coke be applied instead of coal, the +arches, or empty spaces in the clamp or pile,<span class="pagenum"><a name="Page_130" id="Page_130">[130]</a></span> +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.</p> + +<p>“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.</p> + +<p>“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.”</p> + +<p>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,<span class="pagenum"><a name="Page_131" id="Page_131">[131]</a></span> +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.</p> + +<p><em class="italic">Coal-tar</em>, <em class="italic">Oil</em>, and <em class="italic">Pitch</em>.—Another, valuable +product obtainable from pit-coal, is coal-tar.<a name="FNanchor_30" id="FNanchor_30"></a><a href="#Footnote_30" class="fnanchor">[30]</a> +This substance is deposited, in the purification +of the coal-gas, in a separate vessel destined +to receive it.</p> + +<div class="footnote"> + +<p><a name="Footnote_30" id="Footnote_30"></a><a href="#FNanchor_30"><span class="label">[30]</span></a> 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.</p></div> + +<p>The coal-tar is so called from its resembling +common tar in its appearance, and most of its +qualities.</p> + +<p>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<span class="pagenum"><a name="Page_132" id="Page_132">[132]</a></span> +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.</p> + +<p>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.</p> + +<p>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 <a href="#Page_94">page 94</a>.</p> + +<p>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.</p> + +<p>To render the tar fit for use, it requires to +be evaporated to give it a sufficient consistence.<span class="pagenum"><a name="Page_133" id="Page_133">[133]</a></span> +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.</p> + +<p>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.</p> + +<p>Two hundred pounds of tar produce, upon +an average, fifty-three pounds of essential oil.</p> + +<p>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<span class="pagenum"><a name="Page_134" id="Page_134">[134]</a></span> +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.</p> + +<div class="figcenter"> +<p class="caption"><i>Kettle for boiling Tar.</i></p> +<img src="images/illo155.png" alt="" width="350" height="205" /> +</div> + +<p>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 <em class="italic">asphaltum</em>.</p> + +<p><em class="italic">Ammoniacal Fluid.</em>—The properties of the +ammoniacal liquor, which accompanies the tar,<span class="pagenum"><a name="Page_135" id="Page_135">[135]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_136" id="Page_136">[136]</a></span> +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.</p> + +<p>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 <em class="italic">fashion</em>.</p> + +<p>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,<span class="pagenum"><a name="Page_137" id="Page_137">[137]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_138" id="Page_138">[138]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_139" id="Page_139">[139]</a></span> +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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_140" id="Page_140">[140]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_141" id="Page_141">[141]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>If any additional want were wanted for the<span class="pagenum"><a name="Page_142" id="Page_142">[142]</a></span> +coke it will readily be found in the continental +market; coke being much better suited than +coal to the habits of most European nations.</p> + +<p>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.</p> + +<p>It is worthy observation, that the annual +importation of coal into this Metropolis, is +above one million and eighty-eight thousand +chaldrons.<a name="FNanchor_31" id="FNanchor_31"></a><a href="#Footnote_31" class="fnanchor">[31]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_31" id="Footnote_31"></a><a href="#FNanchor_31"><span class="label">[31]</span></a> 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, +</p> +<p> +<em class="italic">1st</em>. 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. +</p> +<p> +<em class="italic">2dly</em>. That this seam, on an average, is at least four feet +and a half thick. +</p> +<p> +<em class="italic">3dly</em>, That 1-6th part of the above extent is sufficient +for pillars to support the roofs of the mines, &c. +</p> +<p> +And, <em class="italic">4thly</em>, It appears, by experiments, that a cubic +yard of coal weighs 1 ton, or 20 cwt. +</p> + +<table summary="Table footnote 31"> + +<tr> +<td> </td> +<td class="center fsize80">London Chaldrons</td> +</tr> + +<tr> +<td class="just top padr3">The total consumption of coal from the rivers Tyne and Wear known from the register to be</td> +<td class="right bot">2,300,000</td> +</tr> + +<tr> +<td class="just top padr3">The number of tons in the above quantity taking the London chaldron at 27 cwt. is</td> +<td class="right bot">3,100,000</td> +</tr> + +<tr> +<td colspan="2" class="just top">Now a ton weight of coal is estimated to occupy in the earth the space of one cubic yard.</td> +</tr> + +<tr> +<td class="just top padr3">The number of cubic yards in the square mile is</td> +<td class="right bot">3,097,600</td> +</tr> + +<tr> +<td class="just top padr3">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</td> +<td class="right bot">1,548,800</td> +</tr> + +<tr> +<td class="just top padr3">And hence the square mile of the beds or seams of coal we are describing contains, of cubic yards and tons of coal</td> +<td class="right bot">4,645,000</td> +</tr> + +<tr> +<td class="just top padr3">A deduction of 1-6th for pillars to support the mine, &c.</td> +<td class="right bot">800,000</td> +</tr> + +<tr> +<td class="just top padr3">The number of tons per square mile</td> +<td class="right bot">5,445,000</td> +</tr> + +</table> + +<p> +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.</p></div> + +<p><span class="pagenum"><a name="Page_143" id="Page_143">[143]</a></span></p> + +<p>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<span class="pagenum"><a name="Page_144" id="Page_144">[144]</a></span> +illumination. But there are two reasons why +this should have less place, because we find, +in Mr. Murdoch’s statement, <a href="#Page_69">page 69</a>, 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.<a name="FNanchor_32" id="FNanchor_32"></a><a href="#Footnote_32" class="fnanchor">[32]</a></p> + +<div class="footnote"> + +<p><a name="Footnote_32" id="Footnote_32"></a><a href="#FNanchor_32"><span class="label">[32]</span></a> See, also, Mr. Ackermann’s statement, <a href="#Page_71">page 71</a>.</p></div> + +<p><em class="italic">2dly</em>, 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,<span class="pagenum"><a name="Page_145" id="Page_145">[145]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_146" id="Page_146">[146]</a></span> +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.</p> + +<p>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.</p> + +<p>From experiments, made by Mr. <span class="smcap">Clegg</span>, on +the effects produced by a number of gas-lights, +of a certain intensity, there is reason to believe<span class="pagenum"><a name="Page_147" id="Page_147">[147]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_148" id="Page_148">[148]</a></span> +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,<a name="FNanchor_33" id="FNanchor_33"></a><a href="#Footnote_33" class="fnanchor">[33]</a> which is a practice commonly<span class="pagenum"><a name="Page_149" id="Page_149">[149]</a></span> +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<span class="pagenum"><a name="Page_150" id="Page_150">[150]</a></span> +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.</p> + +<div class="footnote"> + +<p><a name="Footnote_33" id="Footnote_33"></a><a href="#FNanchor_33"><span class="label">[33]</span></a> 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. +</p> +<p> +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. +</p> +<p> +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. +</p> +<p> +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. +</p> +<p> +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.</p></div> + +<p>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,<span class="pagenum"><a name="Page_151" id="Page_151">[151]</a></span> +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.</p> + +<p>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<span class="pagenum"><a name="Page_152" id="Page_152">[152]</a></span> +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.</p> + +<p>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.</p> + +<p>Those who are familiar with the subject +will readily allow, that there is no more risk<span class="pagenum"><a name="Page_153" id="Page_153">[153]</a></span> +in the action of a gas-light machinery, properly +constructed, than there is in the action +of a steam-engine, built on just principles.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_154" id="Page_154">[154]</a></span> +as we depend on the light to be obtained from +a certain number of candles or oil-lamps.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_155" id="Page_155">[155]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_156" id="Page_156">[156]</a></span> +body, as has been stated, <a href="#Page_98">page 98</a>, 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<span class="pagenum"><a name="Page_157" id="Page_157">[157]</a></span> +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.</p> + +<p><span class="pagenum"><a name="Page_158" id="Page_158">[158]</a></span></p> + +<div class="london_b"><a name="FigLondon" id="FigLondon"></a> +<div class="ill_b"> + +<p class="fsize80 nowrap" style="padding-left: .5em; padding-top: .75em;">Main pipe, leading from the Gas-light station or +apparatus,<br />situated in Brick Lane, near Old St.<a name="FNanchor_34" id="FNanchor_34"></a><a href="#Footnote_34" class="fnanchor">[34]</a></p> + +<p class="fsize80 left" style="padding-left: 37em; padding-top: 3em;">Main pipe, leading from the gaslight apparatus, +or station, at Norton Falgate.<a name="FNanchor_35" id="FNanchor_35"></a><a href="#Footnote_35" class="fnanchor">[35]</a></p> + +<p class="fsize80 left" style="padding-left: .5em; padding-top: 12.5em;">Main pipe, leading from the gaslight apparatus, +or station,<br />in Westminster.<a name="FNanchor_36" id="FNanchor_36"></a><a href="#Footnote_36" class="fnanchor">[36]</a></p> + +</div><!--ill_b--> + +<div class="footnote"> + +<p><a name="Footnote_34" id="Footnote_34"></a><a href="#FNanchor_34"><span class="label">[34]</span></a> <em class="italic">The gasometer at this place is equal in capacity to 22000 cubic feet.</em></p> + +<p><a name="Footnote_35" id="Footnote_35"></a><a href="#FNanchor_35"><span class="label">[35]</span></a> <em class="italic">The capacity of the gasometer here is equal to 15928 cubic feet.</em></p> + +<p><a name="Footnote_36" id="Footnote_36"></a><a href="#FNanchor_36"><span class="label">[36]</span></a> <em class="italic">At this station the gasometer is equal in capacity to 14808 cubic feet.</em></p></div> + +</div><!--london_b--> + +<div class="london_e"> +<div class="ill_e"> +<img src="images/illo_e179.png" alt="Pipe network" width="500" height="385" /> +</div><!--ill_e--> + +<div class="footnote"> + +<p><span class="label">*</span> <em class="italic">The gasometer at this place is equal in capacity to 22000 cubic feet.</em></p> + +<p><span class="label">†</span> <em class="italic">The capacity of the gasometer here is equal to 15928 cubic feet.</em></p> + +<p><span class="label">‡</span> <em class="italic">At this station the gasometer is equal in capacity to 14808 cubic feet.</em></p></div> + +</div><!--london_e--> + +<p>The <a href="#FigLondon">black lines</a> 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, <em class="italic">Pall Mall</em>, should break, it is evident, +on mere inspection, that the gas which is<span class="pagenum"><a name="Page_159" id="Page_159">[159]</a></span> +passing through the main in the <em class="italic">Strand</em>, and +which is also connected with the main in the +<em class="italic">Haymarket</em>, <em class="italic">Piccadilly</em>, and <em class="italic">Coventry Street</em>, +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.</p> + +<p>Further, let us suppose a main pipe should +break in <em class="italic">Piccadilly</em>; in that case, the valve +being shut on each side of the fracture, the gas +would be supplied from the mains in the <em class="italic">Haymarket</em> +and <em class="italic">St. James’s Street</em>. 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<span class="pagenum"><a name="Page_160" id="Page_160">[160]</a></span> +streets.<a name="FNanchor_37" id="FNanchor_37"></a><a href="#Footnote_37" class="fnanchor">[37]</a> 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.</p> + +<div class="footnote"> + +<p><a name="Footnote_37" id="Footnote_37"></a><a href="#FNanchor_37"><span class="label">[37]</span></a> As shown in the <a href="#FigLondon">sketch</a>.</p></div> + +<p>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<span class="pagenum"><a name="Page_161" id="Page_161">[161]</a></span> +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.<a name="FNanchor_38" id="FNanchor_38"></a><a href="#Footnote_38" class="fnanchor">[38]</a> 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,<span class="pagenum"><a name="Page_162" id="Page_162">[162]</a></span> +as well as political recommendations, +for the adoption of the new lights in all manufactories +where work is done by candle-light.</p> + +<div class="footnote"> + +<p><a name="Footnote_38" id="Footnote_38"></a><a href="#FNanchor_38"><span class="label">[38]</span></a> Since the preceding pages have been printed, I have +seen a <em class="italic">self-extinguishing gas-lamp</em>, invented by Mr. <span class="smcap">Clegg</span>. +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. <span class="smcap">Clegg</span> 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.</p></div> + +<p>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<span class="pagenum"><a name="Page_163" id="Page_163">[163]</a></span> +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.</p> + +<p>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.</p> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_164" id="Page_164">[164]</a></span></p> + +<h3 class="noblank"><b>TABULAR VIEW,</b></h3> + +<p class="center fsize80">EXHIBITING</p> + +<p>The quantity of <span class="smcap">Gas</span>, <span class="smcap">Coke</span>, <span class="smcap">Tar</span>, <span class="smcap">Pitch</span>, <span class="smcap">Essential Oil</span>, and <span class="smcap">Ammoniacal Liquor</span>, obtainable from a given +quantity of <span class="smcap">Coal</span>; 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.</p> + +<table class="nowrap esmallest" summary="Table page 164"> + +<tr> +<th colspan="3"> </th> +<th colspan="14" class="center padl1 padr1 br"><em class="italic">Cost of Coal.</em></th> +<th colspan="8" class="center padl1 padr1 br"><em class="italic">Weight of Coal.</em></th> +<th colspan="6" class="center padl1 padr1"><em class="italic">Produce of Gas, in cubic feet.</em></th> +<td rowspan="8" class="bt br bb narrow"> </td> +<td rowspan="8" class="left padl0 narrow">-</td> +<td rowspan="8" class="left padl1 padr1 br wrappable"><a name="FNanchor_39" id="FNanchor_39"></a><a href="#Footnote_39" class="fnanchor">[39]</a>Equal to as many tallow candles, 12 in the pound, burning two hours; or to</td> +<th colspan="3" class="center padl1 padr1"><em class="italic">Candles.</em></th> +</tr> + +<tr> +<th colspan="3"> </th> +<th colspan="4" class="center padl1 padr1">Mini-<br />mum.</th> +<th> </th> +<th colspan="4" class="center padl1 padr1">Maxi-<br />mum.</th> +<th> </th> +<th colspan="4" class="center padl1 padr1 br">Aver-<br />age.</th> +<th colspan="2" class="center padl1 padr1">Min.</th> +<th> </th> +<th colspan="2" class="center padl1 padr1">Max.</th> +<th> </th> +<th colspan="2" class="center padl1 padr1 br">Aver.</th> +<th class="center padl1 padr1">Min.</th> +<th> </th> +<th class="center padl1 padr1">Max.</th> +<th> </th> +<th colspan="2" class="center padl1 padr1">Aver.</th> +<td class="right padl1 padr1">9,516<br />8,651</td> +<td class="right padr1">11<br />10</td> +<td class="left">to the pound.<br /><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td class="left">One Chal.<br />of Coal,<br />from 25<br />to 28 cwt.</td> +<td class="bt br bb narrow"> </td> +<td class="left padl0">-</td> +<td class="right padl1 padr0">40</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">to</td> +<td class="right padl1 padr0">60</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">—</td> +<td class="right padl1 padr0">50</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2" class="br"> </td> +<td class="right padl1 padr0">2,800</td> +<td> </td> +<td class="center">to</td> +<td class="right padl1 padr0">3,136</td> +<td> </td> +<td class="center">—</td> +<td class="right padl1 padr0">2,968</td> +<td class="br"> </td> +<td class="right padl1 padr1">8,906</td> +<td class="center">to</td> +<td class="right padl1 padr1">11,872</td> +<td class="center">—</td> +<td class="right padl1 padr0">10,388</td> +<td class="left padl0 padr0"><a href="#Footnote_39" class="fnanchor">[39]</a></td> +<td class="right padl1 padr1">7,786<br />6,921<br />6,556<br />5,194</td> +<td class="right padr1">10<br />9<br />8<br />7</td> +<td class="left"><span class="noshow">to th</span>do.<br /><span class="noshow">to th</span>do.<br /><span class="noshow">to th</span>do.<br /><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Ton</td> +<td class="right padl1 padr0">30</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">to</td> +<td class="right padl1 padr0">48</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">—</td> +<td class="right padl1 padr0">38</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">6</td> +<td class="left padl0 padr1 br"><i>d</i></td> +<td colspan="6"> </td> +<td class="right padl1 padr0">2,240</td> +<td class="br"> </td> +<td class="right padl1 padr1">6,720</td> +<td class="center">to</td> +<td class="right padl1 padr1">8,960</td> +<td class="center">—</td> +<td class="right padl1 padr0">7,840</td> +<td> </td> +<td class="right padl1 padr1">4,325</td> +<td class="right padr1">5</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Sack</td> +<td class="right padl1 padr0">3</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">4</td> +<td class="left padl0 padr1"><i>d</i></td> +<td class="center">to</td> +<td class="right padl1 padr0">5</td> +<td class="left padl0 padr1"><i>s</i></td> +<td colspan="2"> </td> +<td class="center">—</td> +<td class="right padl1 padr0">4</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">2</td> +<td class="left padl0 padr1 br"><i>d</i></td> +<td class="right padl1 padr0">233</td> +<td> </td> +<td class="center">to</td> +<td class="right padr0">261</td> +<td> </td> +<td class="center">—</td> +<td class="right padl1 padr0">247</td> +<td class="br"> </td> +<td class="right padl1 padr1">741</td> +<td class="center">to</td> +<td class="right padl1 padr1">988</td> +<td class="center">—</td> +<td class="right padl1 padr0">814</td> +<td> </td> +<td class="right padl1 padr1">3,463</td> +<td class="right padr1">4</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Bushel</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">2</td> +<td class="left padl0 padr1"><i>d</i></td> +<td class="center">to</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">8</td> +<td class="left padl0 padr1"><i>d</i></td> +<td class="center">—</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1"><i>s</i></td> +<td class="right padr0">5</td> +<td class="left padl0 padr1 br"><i>d</i></td> +<td class="right padl1 padr0">78</td> +<td> </td> +<td class="center">to</td> +<td class="right padl1 padr0">87</td> +<td> </td> +<td class="center">—</td> +<td class="right padl1 padr0">82</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">247</td> +<td class="center">to</td> +<td class="right padl1 padr1">330</td> +<td class="center">—</td> +<td class="right padl1 padr0">290</td> +<td> </td> +<td class="right padl1 padr1">2,595</td> +<td class="right padr1">3</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Peck</td> +<td colspan="2"> </td> +<td class="right padl1 padr0">3</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center">to</td> +<td colspan="2"> </td> +<td class="right padr0">5</td> +<td class="left padl0 padr1"><i>d</i></td> +<td class="center">—</td> +<td colspan="2"> </td> +<td class="right padl1 padr0">4</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr0">19</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center">to</td> +<td class="right padl1 padr0">21</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>4</sub></td> +<td class="center">—</td> +<td class="right padl1 padr0">20</td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>4</sub></td> +<td class="right padl1 padr1">61</td> +<td class="center">to</td> +<td class="right padl1 padr1">82</td> +<td class="center">—</td> +<td class="right padl1 padr0">71</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">1,730</td> +<td class="right padr1">2</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td colspan="3" class="left">One Pound</td> +<td colspan="13"> </td> +<td class="left padl0 padr1 br"><sup>1</sup>⁄<sub>4</sub></td> +<td colspan="6"> </td> +<td class="right padl1 padr0">1</td> +<td class="br"> </td> +<td class="right padl1 padr1">3</td> +<td class="center">to</td> +<td class="right padl1 padr1">4</td> +<td class="center">—</td> +<td class="right padl1 padr0">3</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="right padl1 padr1">866</td> +<td class="right padr1">1</td> +<td class="left"><span class="noshow">to th</span>do.</td> +</tr> + +<tr> +<td class="blankabove"> </td> +<td colspan="36" class="just wrappable blankabove"><span class="smcap">Coke.</span>—One chaldron of coal, from 25 to 28 cwt. gives 1<sup>1</sup>⁄<sub>4</sub> to 1½ chaldron of Coke.</td> +</tr> + +<tr> +<td> </td> +<td colspan="36" class="just wrappable"><span class="smcap">Tar.</span>—One chaldron of coal, from 25 to 28 cwt. gives from 150 to 180lb. of Tar,<a href="#Footnote_39" class="fnanchor">[39]</a> or 15 to 18 ale gallons, 10lb. each.</td> +</tr> + +<tr> +<td> </td> +<td colspan="36" class="just wrappable"><span class="smcap">Ammoniacal Liquor.</span>—One chaldron of coal, gives from 220 to 240lb. of Ammoniacal Liquor, or 22 to 24 ale gallons.</td> +</tr> + +</table> + +<div class="footnote"> + +<p><a name="Footnote_39" id="Footnote_39"></a><a href="#FNanchor_39"><span class="label">[39]</span></a>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.</p></div> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_165" id="Page_165">[165]</a></span></p> + +<p class="center"><i>Tabular View, exhibiting the illuminating power of Coal-Gas, compared with the illuminating power +of Tallow Candles of different sizes.</i></p> + +<table class="nowrap" summary="Table page 165"> + +<tr> +<th colspan="11" class="center padl1 padr1">One chaldron of Coal produces, according to weight and quality,</th> +</tr> + +<tr class="fsize80"> +<th colspan="6"> </th> +<th class="center padl1 padr1">Burning.</th> +<th class="center padl1 padr1">Candles.</th> +<th class="right padl1 padr1">12 to 1lb.</th> +<th> </th> +<th class="right padl1 padr1">6 to 1lb.</th> +</tr> + +<tr> +<th colspan="4" class="center padl1 padr1 fsize80">Cubic feet of Gas.</th> +<th class="center padl1 padr1 fsize80">Average.</th> +<td class="right padr1">1</td> +<td class="center">hour</td> +<td class="center padl1 padr1">=</td> +<td class="right padr1">21,000</td> +<td class="center padl1 padr1">=</td> +<td class="right padl1 padr1">10,500</td> +</tr> + +<tr> +<td class="left">From</td> +<td class="right padl1 padr1">9,000</td> +<td class="center">to</td> +<td class="right padl1 padr1">12,000</td> +<td class="right padl1 padr1">10,500</td> +<td class="right padl1 padr1">2</td> +<td class="center">hours</td> +<td class="center">=</td> +<td class="right padl1 padr1">10,500</td> +<td class="center">=</td> +<td class="right padl1 padr1">5,250</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">6,000</td> +<td> </td> +<td class="right padl1 padr1">8,000</td> +<td class="right padl1 padr1">7,000</td> +<td class="right padl1 padr1">3</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">7,000</td> +<td class="center">=</td> +<td class="right padl1 padr1">3,500</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">4,500</td> +<td> </td> +<td class="right padl1 padr1">6,000</td> +<td class="right padl1 padr1">5,250</td> +<td class="right padl1 padr1">4</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">5,250</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,625</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">3,600</td> +<td> </td> +<td class="right padl1 padr1">4,800</td> +<td class="right padl1 padr1">4,400</td> +<td class="right padl1 padr1">5</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">4,400</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,200</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">3,000</td> +<td> </td> +<td class="right padl1 padr1">4,000</td> +<td class="right padl1 padr1">3,500</td> +<td class="right padl1 padr1">6</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">3,500</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,750</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">2,571</td> +<td> </td> +<td class="right padl1 padr1">3,428</td> +<td class="right padl1 padr1">3,005</td> +<td class="right padl1 padr1">7</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">3,005</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,502</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">2,250</td> +<td> </td> +<td class="right padl1 padr1">3,000</td> +<td class="right padl1 padr1">2,625</td> +<td class="right padl1 padr1">8</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,625</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,312</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">2,000</td> +<td> </td> +<td class="right padl1 padr1">2,666</td> +<td class="right padl1 padr1">2,333</td> +<td class="right padl1 padr1">9</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,333</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,166</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,800</td> +<td> </td> +<td class="right padl1 padr1">2,100</td> +<td class="right padl1 padr1">2,100</td> +<td class="right padl1 padr1">10</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">2,100</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,050</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,636</td> +<td> </td> +<td class="right padl1 padr1">2,191</td> +<td class="right padl1 padr1">1,913</td> +<td class="right padl1 padr1">11</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,913</td> +<td class="center">=</td> +<td class="right padl1 padr1">956</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,500</td> +<td> </td> +<td class="right padl1 padr1">2,000</td> +<td class="right padl1 padr1">1,750</td> +<td class="right padl1 padr1">12</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,750</td> +<td class="center">=</td> +<td class="right padl1 padr1">875</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,384</td> +<td> </td> +<td class="right padl1 padr1">1,846</td> +<td class="right padl1 padr1">1,615</td> +<td class="right padl1 padr1">13</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,615</td> +<td class="center">=</td> +<td class="right padl1 padr1">807</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,285</td> +<td> </td> +<td class="right padl1 padr1">1,714</td> +<td class="right padl1 padr1">1,499</td> +<td class="right padl1 padr1">14</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,499</td> +<td class="center">=</td> +<td class="right padl1 padr1">749</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,200</td> +<td> </td> +<td class="right padl1 padr1">1,600</td> +<td class="right padl1 padr1">1,400</td> +<td class="right padl1 padr1">15</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,400</td> +<td class="center">=</td> +<td class="right padl1 padr1">700</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,125</td> +<td> </td> +<td class="right padl1 padr1">1,500</td> +<td class="right padl1 padr1">1,312</td> +<td class="right padl1 padr1">16</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,312</td> +<td class="center">=</td> +<td class="right padl1 padr1">656</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,058</td> +<td> </td> +<td class="right padl1 padr1">1,111</td> +<td class="right padl1 padr1">1,234</td> +<td class="right padl1 padr1">17</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,234</td> +<td class="center">=</td> +<td class="right padl1 padr1">617</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">1,000</td> +<td> </td> +<td class="right padl1 padr1">1,333</td> +<td class="right padl1 padr1">1,166</td> +<td class="right padl1 padr1">18</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,166</td> +<td class="center">=</td> +<td class="right padl1 padr1">583</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">947</td> +<td> </td> +<td class="right padl1 padr1">1,263</td> +<td class="right padl1 padr1">1,105</td> +<td class="right padl1 padr1">19</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,105</td> +<td class="center">=</td> +<td class="right padl1 padr1">552</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">900</td> +<td> </td> +<td class="right padl1 padr1">1,200</td> +<td class="right padl1 padr1">1,050</td> +<td class="right padl1 padr1">20</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,050</td> +<td class="center">=</td> +<td class="right padl1 padr1">525</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">857</td> +<td> </td> +<td class="right padl1 padr1">1,143</td> +<td class="right padl1 padr1">1,000</td> +<td class="right padl1 padr1">21</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">1,000</td> +<td class="center">=</td> +<td class="right padl1 padr1">500</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">818</td> +<td> </td> +<td class="right padl1 padr1">1,095</td> +<td class="right padl1 padr1">956</td> +<td class="right padl1 padr1">22</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">956</td> +<td class="center">=</td> +<td class="right padl1 padr1">478</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">783</td> +<td> </td> +<td class="right padl1 padr1">1,044</td> +<td class="right padl1 padr1">913</td> +<td class="right padl1 padr1">23</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">913</td> +<td class="center">=</td> +<td class="right padl1 padr1">456</td> +</tr> + +<tr> +<td> </td> +<td class="right padl1 padr1">750</td> +<td> </td> +<td class="right padl1 padr1">1,000</td> +<td class="right padl1 padr1">875</td> +<td class="right padl1 padr1">21</td> +<td class="center">ditto</td> +<td class="center">=</td> +<td class="right padl1 padr1">875</td> +<td class="center">=</td> +<td class="right padl1 padr1">437</td> +</tr> + +</table> + +<p>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:</p> + +<table class="nowrap" summary="Table page 165-2"> + +<tr> +<td> </td> +<td class="right padl1 padr1">1</td> +<td class="center">lb.</td> +<td class="center padl1 padr1">=</td> +<td class="right">2968th</td> +<td class="left padl1">part of a chaldron.</td> +</tr> + +<tr> +<td class="left">One peck</td> +<td class="right padl1 padr1">20</td> +<td> </td> +<td class="center">=</td> +<td class="right">148th</td> +<td class="center">ditto.</td> +</tr> + +<tr> +<td class="left">One bushel</td> +<td class="right padl1 padr1">82</td> +<td> </td> +<td class="center">=</td> +<td class="right">36th</td> +<td class="center">ditto.</td> +</tr> + +<tr> +<td class="left">One sack</td> +<td class="right padl1 padr1">248</td> +<td> </td> +<td class="center">=</td> +<td class="right">12th</td> +<td class="center">ditto.</td> +</tr> + +</table> + +<p><span class="smcap">Rule.</span>—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.</p> + +<p><span class="smcap">Example.</span>—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.</p> + +<hr class="sect" /> + +<p><span class="pagenum"><a name="Page_166" id="Page_166">[166]</a></span></p> + +<h3>DESCRIPTION<br /> +<span class="fsize60">OF</span><br /> +THE GAS-LIGHT APPARATUS.</h3> + +<h4><a href="#Plate1">PLATE I.</a></h4> + +<p>Exhibits a perspective view of a gas-light apparatus,<a name="FNanchor_40" id="FNanchor_40"></a><a href="#Footnote_40" class="fnanchor">[40]</a> +for lighting factories, or small districts of +houses. It consists of the following parts: which +may be considered separately.</p> + +<div class="footnote"> + +<p><a name="Footnote_40" id="Footnote_40"></a><a href="#FNanchor_40"><span class="label">[40]</span></a> This apparatus was erected by Mr. <span class="smcap">Clegg</span>, and is now in +action at Mr. <span class="smcap">Ackerman</span>’s establishment, in this metropolis.</p></div> + +<p><a href="#Plate1"><span class="smcap">Fig.</span> 1.</a> The <em class="italic">Retort Furnace</em>, for distilling the +coals. It is built of brick-work. The bricks which +are exposed to the immediate action of the fire, +are <em class="italic">Welch tumps</em>, or fire-bricks; they are bedded +in clay, or Windsor loam.</p> + +<p><a href="#Plate1"><span class="smcap">Fig.</span> 2.</a> The <em class="italic">Tar Cistern</em>, 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.</p> + +<p><span class="pagenum"><a name="Page_167" id="Page_167">[167]</a></span></p> + +<p><a href="#Plate1"><span class="smcap">Fig.</span> 3.</a> The <em class="italic">Lime Machine</em>, for purifying the +crude coal-gas, and to render it fit for use. The +construction of this machine will be explained in +<a href="#Plate7">plate <span class="smcap">VII</span></a>. It is put together of cast-iron plates.</p> + +<p><a href="#Plate1"><span class="smcap">Fig.</span> 4.</a> The <em class="italic">Gasometer</em>, 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.</p> + +<p>The action of these different parts of the apparatus +will be obvious from the following explanation:</p> + +<p><span class="smcapall">A</span>, <span class="smcapall">A</span>, are two iron retorts, placed horizontally, +and side by side, in the furnace; the mouth of the<span class="pagenum"><a name="Page_168" id="Page_168">[168]</a></span> +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.</p> + +<p>When the operation commences, the inner vessel +of the gasometer, <a href="#Plate1">fig. 4</a> 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 <span class="smcapall">B</span>, <span class="smcapall">B</span>, into the horizontal pipe or main +condenser <span class="smcapall">C</span>, with which they are connected. The +liquid which is distilled, collects in the pipe, or +main condenser, <span class="smcapall">C</span>, where it is retained until its +quantity has risen so high as to discharge itself into +the pipe <span class="smcapall">D</span>, which is connected with the upper part +of one of the extremities of the condenser, <span class="smcapall">C</span>. One +of the extremities of the pipes, <span class="smcapall">B</span>, <span class="smcapall">B</span>, therefore become +immersed into the liquid contained in the +main condenser or pipe <span class="smcapall">C</span>, whilst the vaporous or +condensible fluid, after having overcome the pressure +there opposed to it, is transported into the pipe <span class="smcapall">E</span>, +which, after passing in a serpentine direction, <span class="smcapall">E</span>, <span class="smcapall">E</span>,<span class="pagenum"><a name="Page_169" id="Page_169">[169]</a></span> +&c. through the exterior vessel or cistern of the gasometer, +terminates in the tar-vessel, <a href="#Plate1">fig. 2</a>. Thus the +vaporous fluids are condensed by passing through the +serpentine pipe, <span class="smcapall">E</span>, <span class="smcapall">E</span>, &c. and become deposited in +the tar-cistern, <a href="#Plate1">fig. 2</a>; whilst the non-condensible or +gazeous products are made to proceed by the pipe <span class="smcapall">F</span>, +which branches off from the pipe <span class="smcapall">E</span>, into the lime +machine, <a href="#Plate1">fig. 3</a>. 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 <span class="smcapall">G</span>, +into the perpendicular pipe <span class="smcapall">H</span>, 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 <span class="smcapall">I</span>, 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 <span class="smcapall">H</span>, displaces the water from +the receiver <span class="smcapall">I</span>, 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 <span class="smcapall">I</span>, 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<span class="pagenum"><a name="Page_170" id="Page_170">[170]</a></span> +with this substance in the lime machine, <a href="#Plate1">fig. 3</a>. +After rising through the water in the gasometer +cistern, it enters into the gasometer, which then ascends +as the gas accumulates in it.</p> + +<p>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 <span class="smcapall">K</span>, to the burners, or main +pipe, which communicates with the gas burners or +lamps. <span class="smcapall">L</span>, 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, +<span class="smcapall">L</span>, may be conveyed by the curved pipe <span class="smcapall">M</span>, without +admitting common air. <span class="smcapall">N</span>, <span class="smcapall">N</span>, 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<span class="pagenum"><a name="Page_171" id="Page_171">[171]</a></span> +machine, the contents of which should be renewed +occasionally. This pipe also conveys the necessary +water into the barrel, <span class="smcapall">L</span>. <span class="smcapall">O</span>, is a waste-pipe, to convey +the water as it becomes impregnated with the +impurities of the gas, out of the gasometer cistern. +<span class="smcapall">P</span>, is an agitator, to stir up the contents of the lime +machine occasionally, <span class="smcapall">Q</span>, <span class="smcapall">Q</span>, are two iron rods, which +serve as stays to guide the motion of the gasometer. +<span class="smcapall">R</span>, 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. <span class="smcapall">S</span>, is the waste +pipe of the lime machine, to remove the insoluble +parts of the lime. <span class="smcapall">T</span>, 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. <span class="smcapall">U</span> 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.</p> + +<p>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<span class="pagenum"><a name="Page_172" id="Page_172">[172]</a></span> +the right-hand corner of <a href="#Plate7">plate VII.</a> 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.</p> + +<h4><a href="#Plate2">PLATE II.</a></h4> + +<p>Represents a Portable experimental Gas Apparatus +for exhibiting, in the small way, the general +nature of the gas-light illumination.—It is described +<a href="#Page_79">page 79</a>.</p> + +<h4><a href="#Plate3">PLATES III.</a> <a href="#Plate4">IV.</a> <a href="#Plate5">V.</a></h4> + +<p>Show designs of various kinds of Gas Lamps, +Chandeliers, Candelabras, &c.—See <a href="#Page_114">pages 114</a>, <a href="#Page_118">118</a>, +<a href="#Page_140">140</a>.</p> + +<h4><a href="#Plate6">PLATE VI.</a></h4> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 1.</a> Exhibits a design of the <em class="italic">gasometer +framing</em>, or <em class="italic">skeleton</em>, which serves to give stability +and strength to the gasometer. It consists of +wooden frame work, marked <span class="smcapall">A</span>, <span class="smcapall">A</span>, <span class="smcapall">A</span>, interlaced<span class="pagenum"><a name="Page_173" id="Page_173">[173]</a></span> +with iron rods, <span class="smcapall">B</span>, <span class="smcapall">B</span>, <span class="smcapall">B</span>, &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.</p> + +<p>The rest of the sketches represent various kinds +of gas pipes employed as <em class="italic">mains</em> for conveying the +gas, and the methods of connecting them.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 2.</a> Represents a longitudinal section of a +<em class="italic">Spigot</em> and <em class="italic">Faucet Pipe</em>. These kinds of pipes are +applicable in most cases as mains for conveying gas. +<span class="smcapall">A</span>, is called the spigot, and <span class="smcapall">B</span>, the faucet. They +are joined together, and made air tight, by iron +cement, the composition of which is as follows:</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class="pagenum"><a name="Page_174" id="Page_174">[174]</a></span> +proportion of iron,) all the parts of which cohere +strongly together.</p> + +<p>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<sup>1</sup>⁄<sub>2</sub> inches deep, and has the spigot inserted +1<sup>1</sup>⁄<sub>2</sub> 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<sup>1</sup>⁄<sub>2</sub> +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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 3.</a> 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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 4.</a> Represents a longitudinal section of two +flanch pipes, and the modes of connecting them. +<span class="smcapall">A</span> and <span class="smcapall">B</span>, show the parts of the pipes; and <span class="smcapall">C</span> and +<span class="smcapall">D</span>, the flanches. These pipes are also joined together, +and rendered air-tight, by interposing between<span class="pagenum"><a name="Page_175" id="Page_175">[175]</a></span> +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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 5.</a> Profile view of the same kind of pipes +connected together, <span class="smcapall">A</span> and <span class="smcapall">B</span>, the pipes; <span class="smcapall">C</span> and <span class="smcapall">D</span>, +the flanches; <span class="smcapall">E</span> and <span class="smcapall">F</span>, the bolts.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 6.</a> 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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 7.</a> Exhibits the method of connecting spigot +and faucet pipes when they have a round turn. <span class="smcapall">A</span> +and <span class="smcapall">B</span>, the junctures of the pipes.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 8.</a> Represents a longitudinal section of the +mode of joining pipes by means of what is called +a <em class="italic">thimble joint</em>. The junctures of the pipes to be +connected, are made air tight, as mentioned already, +by iron cement. <span class="smcapall">A</span>, the thimble or small cylinder, +with projecting edges, which unites the pipes <span class="smcapall">B</span>, <span class="smcapall">C</span>.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 9.</a> 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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 10.</a> Section of the same.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 11.</a> Represents a profile view of what is +called the <em class="italic">saddle joint</em>. It is employed for taking +off a branch-pipe. The branch has a piece <span class="smcapall">A</span> <span class="smcapall">B</span>, +formed on its end, and fits round one-half of the +outside of the pipe from which it is to proceed. +<span class="smcapall">C</span>, is called the saddle, which fits round the other +half of the pipe. The parts are secured together<span class="pagenum"><a name="Page_176" id="Page_176">[176]</a></span> +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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 12.</a> Section of the saddle-joint.</p> + +<p>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.</p> + +<p><a href="#Plate6"><span class="smcap">Fig.</span> 13.</a> Shows a reservoir for collecting the water +of condensation which might accumulate in the +pipes. It consists of a receptacle, <span class="smcapall">A</span>, in which the +water may pass; <span class="smcapall">B</span>, 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.</p> + +<p><span class="pagenum"><a name="Page_177" id="Page_177">[177]</a></span></p> + +<h4><a href="#Plate7">PLATE VII.</a></h4> + +<p>Exhibits a perpendicular section of a gas-light +apparatus, calculated for lighting towns, or large +districts of streets and houses.</p> + +<p><a href="#Plate7"><span class="smcap">Fig.</span> 1.</a> 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. <span class="smcapall">A</span>, <span class="smcap">A,</span> shows two of the retorts +placed horizontally above each other; <span class="smcapall">B</span>, the fire-place; +<span class="smcapall">C</span>, the flue which causes the fire to circulate +round the retorts so as to heat them equally in +every part; <span class="smcapall">D</span>, the opening of the flue where the +fire passes into the chimney; <span class="smcapall">E</span>, the ash-pit; <span class="smcapall">F</span>, a +chamber in front of the retort furnace, into which +the orifice or mouth of the retorts project; <span class="smcapall">G</span>, <span class="smcapall">G</span>, the +doors of the chamber, to enable the workmen to +charge and discharge the retorts; <span class="smcapall">H</span>, a funnel shaped +hole at the floor of the chamber <span class="smcapall">F</span>, through which +the red hot coke as it is discharged from the retorts +passes into the arched vault <span class="smcapall">I</span>; <span class="smcapall">K</span>, the syphon tube; +<span class="smcapall">L</span>, the horizontal condenser<a name="FNanchor_41" id="FNanchor_41"></a><a href="#Footnote_41" class="fnanchor">[41]</a>—the action of both of +these pipes have been already explained, <a href="#Page_168">p. 168</a>; +<span class="smcapall">M</span>, main pipe, which conveys the liquid substances +from the condenser, to the tar cistern, <a href="#Plate7">fig. 3</a>, and<span class="pagenum"><a name="Page_178" id="Page_178">[178]</a></span> +which conducts also the gazeous products into the +lime machine, <a href="#Plate7">fig. 2</a>; <span class="smcapall">N</span> <span class="smcapall">N</span>, shows that part of the +pipe which is interposed between the tar cistern, +<a href="#Plate7">fig. 3</a>, and the condensing pipe <span class="smcapall">M</span>,—it passes in a +serpentine direction along the inner sides of the +gasometer cistern, and, like the so-called <em class="italic">worm</em> in +a distillatory apparatus, condenses the products +which escape in a vaporous state from the condenser +<span class="smcapall">L</span>; <span class="smcapall">O</span>, shows the place where the serpentine pipe +<span class="smcapall">N</span> <span class="smcapall">N</span>, passes again out of the gasometer cistern, and +its communication with the lime machine, <a href="#Plate7">fig. 2</a>, and +tar chamber, <a href="#Plate7">fig. 3</a>. The action of the lime machine +is as follows: The liquid products evolved from the +coal, having been deposited in the tar cistern, <a href="#Plate7">fig. 3</a>, +by means of the serpentine pipe <span class="smcapall">N</span>, <span class="smcapall">N</span>, the gazeous products +which accompany it, are conveyed by means of +the pipe <span class="smcapall">P</span>, which branches out from the pipe <span class="smcapall">O</span>, into +the interior receptacle of the lime machine marked <span class="smcapall">Q</span>, +which consists of a vessel open at the bottom, and +closed at the top, where it communicates with the +pipe <span class="smcapall">O</span>. As the gas accumulates in the interior part <span class="smcapall">Q</span>, +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 <span class="smcapall">R</span>, <span class="smcapall">R</span>, <span class="smcapall">R</span>, <span class="smcapall">R</span>, into the outer +vessel, <span class="smcapall">S</span>, of the lime machine and from thence it is +conducted away by the pipe <span class="smcapall">T</span>, <span class="smcapall">T</span>, <span class="smcapall">T</span>, into the additional +washing apparatus, of the gasometer; <a href="#Plate7">fig. 4</a>, +the construction of this apparatus, greatly resembles +the lime machine, <a href="#Plate7">fig. 2</a>, namely, <span class="smcapall">V</span>, is a water +pipe, proceeding from a cistern <span class="smcapall">U</span>, placed 3 or 4 feet +above the orifice of the pipe <span class="smcapall">V</span>; <span class="smcapall">T</span>, <span class="smcapall">T</span>, is the gas-pipe,<span class="pagenum"><a name="Page_179" id="Page_179">[179]</a></span> +covered with a hood, marked <span class="smcapall">W</span>, 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 <span class="smcapall">W</span>, meets with +a shower of water delivered by the pipe <span class="smcapall">V</span>. 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; <span class="smcapall">Y</span>, 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 <span class="smcapall">V</span>, 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 <span class="smcapall">L</span>, by means of the +pipe <span class="smcapall">K</span>, 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 <span class="smcapall">K</span>, <span class="smcapall">K</span>, becomes immersed and hermetically +sealed by the liquid which the condenser <span class="smcapall">L</span>, 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 <span class="smcapall">M</span>, from whence they are +transported into the tar cistern, <a href="#Plate7">fig. 3</a>, by means of +the system of pipes <span class="smcapall">N</span>, <span class="smcapall">N</span>, <span class="smcapall">O</span>, whilst the gazeous products +are made to pass by means of the branch +pipe <span class="smcapall">P</span>, into the lime machine, <a href="#Plate7">fig. 2</a>. From this +part of the apparatus the gas passes through the +pipe <span class="smcapall">T</span>, <span class="smcapall">T</span>, <span class="smcapall">T</span>, into the additional or smaller washing +apparatus placed upon a tressel in the cistern of the<span class="pagenum"><a name="Page_180" id="Page_180">[180]</a></span> +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 <span class="smcapall">A</span>, closed at the +top, and fixed in one corner of the gasometer, but +open at the bottom; it includes another pipe marked +<span class="smcapall">B</span>, which communicates with the main pipe leading +to the burners, or place where the gas is wanted. The +pipe <span class="smcapall">A</span>, which slides over the pipe <span class="smcapall">B</span>, is perforated at +the top, the gas passes through these perforations +and is thus made to enter into the pipe <span class="smcapall">B</span>, and +disposed of as mentioned. <span class="smcapall">C</span>, <span class="smcapall">C</span>, 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 <span class="smcapall">D</span>, which reaches +through the roof of the gasometer house, and thus +the superfluous quantity of gas is conveyed away +into the open air.</p> + +<div class="footnote"> + +<p><a name="Footnote_41" id="Footnote_41"></a><a href="#FNanchor_41"><span class="label">[41]</span></a> 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 <span class="smcapall">K</span>, <span class="smcapall">K</span>, and not to discharge itself into the pipe <span class="smcapall">M</span>, till +this has been effected. The partition is seen in the drawing.</p></div> + +<p>The cylindrical vessel <span class="smcapall">P</span>, of <a href="#Plate7">fig. 3</a>, surrounding +the orifice of the pipe <span class="smcapall">O</span>, which delivers the tar into +the tar cistern, <a href="#Plate7">fig. 3</a>, 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 +<span class="smcapall">L</span>, is placed, as shown in the drawing, higher +than the level of the water in the gasometer cistern,<span class="pagenum"><a name="Page_181" id="Page_181">[181]</a></span> +to allow a free descent of the distillatory liquids as +they pass from this vessel along into the pipes <span class="smcapall">M</span>, <span class="smcapall">N</span>, <span class="smcapall">O</span>, +&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—<span class="smcapall">E</span>, <span class="smcapall">E</span>, are two iron stays—<span class="smcapall">G</span>, <span class="smcapall">G</span>, are +friction wheels.</p> + +<hr class="sect" /> + +<h3 class="light"><i>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.</i><a name="FNanchor_42" id="FNanchor_42"></a><a href="#Footnote_42" class="fnanchor">[42]</a></h3> + +<div class="footnote"> + +<p><a name="Footnote_42" id="Footnote_42"></a><a href="#FNanchor_42"><span class="label">[42]</span></a> For this elegant contrivance we are also indebted to +Mr. <span class="smcap">Clegg</span>.</p></div> + +<p>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 <a href="#Page_88">p. 88</a>, and <a href="#Page_167">167</a>. To +render its pressure uniform, we first take the <em class="italic">absolute</em> +weight of that part of the gasometer which becomes +immersed in the water, and knowing the <em class="italic">specific +weight</em> 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<span class="pagenum"><a name="Page_182" id="Page_182">[182]</a></span> +of which the gasometer is composed. For example, +let us suppose that the part of the gasometer which +becomes immersed in water weighs 861 <i>lb.</i> 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<i>lb.</i> 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<i>lbs.</i> then the chain +of the gasometer equal in length to the height of +the gasometer, immersed into the water must weigh +224<i>lb.</i> 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.</p> + +<hr class="sect" /> + +<h3>DIRECTIONS TO WORKMEN<br /> +<span class="fsize60">ATTENDING</span><br /> +THE GAS-LIGHT APPARATUS<a name="FNanchor_43" id="FNanchor_43"></a><a href="#Footnote_43" class="fnanchor">[43]</a>.</h3> + +<div class="footnote"> + +<p><a name="Footnote_43" id="Footnote_43"></a><a href="#FNanchor_43"><span class="label">[43]</span></a> Copied from a printed direction drawn up by Mr. Clegg, +for the use of workmen.</p></div> + +<p>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<span class="pagenum"><a name="Page_183" id="Page_183">[183]</a></span> +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.</p> + +<p>The bridge or row of bricks of the flue <span class="smcapall">C</span>, 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.</p> + +<p>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<span class="pagenum"><a name="Page_184" id="Page_184">[184]</a></span> +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.</p> + +<p>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.</p> + +<p><span class="pagenum"><a name="Page_185" id="Page_185">[185]</a></span></p> + +<hr class="sect" /> + +<h3>ESTIMATE<br /> +<span class="fsize60">OF</span><br /> +THE PRICE<br /> +<span class="fsize60">OF</span><br /> +A GAS-LIGHT APPARATUS,<br /> +<span class="fsize80"><em class="italic">IF ERECTED IN LONDON</em>,</span></h3> + +<p class="center">Capable of affording, every 24 hours, Light equal to 40,000 Tallow +Candles, six in the pound, burning one hour.</p> + +<table summary="Table page 185"> + +<tr> +<th> </th> +<th class="center padl3 padr1">£.</th> +<th class="center padl1 padr1">s.</th> +</tr> + +<tr> +<td class="left top padr3">Gasometer, to contain 10,000 cubic feet of gas</td> +<td class="right bot padl1 padr1">236</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Wheel-work, regulating chain, ballance-weight for ditto, with wooden framing</td> +<td class="right bot padl1 padr1">160</td> +<td class="right bot padl1 padr1">11</td> +</tr> + +<tr> +<td class="left top padr3">Wrought iron cistern for gasometer—36 feet wide, 24 feet long and 16 feet deep</td> +<td class="right bot padl1 padr1">500</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="3" class="center">(<em class="italic">It would weigh about 16 tons.</em>)</td> +</tr> + +<tr> +<td class="left top padr3">Wooden framing built around it, to secure ditto</td> +<td class="right bot padl1 padr1">150</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Condenser, cistern and communicating pipes</td> +<td class="right bot padl1 padr1">126</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Lime machine, made of cast iron plates</td> +<td class="right bot padl1 padr1">82</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Gasometer-house, built of frame-work and weather-boarded</td> +<td class="right bot padl1 padr1">250</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Twenty-four retorts set in brick-work, with furnaces for ditto, compleat</td> +<td class="right bot padl1 padr1">336</td> +<td class="right bot padl1 padr1">0</td> +</tr> + +<tr> +<td class="left top padr3">Sundries</td> +<td class="right bot padl1 padr1 bb">100</td> +<td class="right bot padl1 padr1 bb">0</td> +</tr> + +<tr> +<td> </td> +<td class="right bot padl1 padr1">£ 1940</td> +<td class="right bot padl1 padr1">11</td> +</tr> + +</table> + +<hr class="tb" /> + +<p>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<i>l.</i> if erected in this metropolis.</p> + +<p><span class="pagenum"><a name="Page_186" id="Page_186">[186]</a></span></p> + +<h3 class="light">LONDON Price List of the most essential articles<a name="FNanchor_44" id="FNanchor_44"></a><a href="#Footnote_44" class="fnanchor">[44]</a> employed +in the erection of a Gas-Light apparatus.</h3> + +<div class="footnote"> + +<p><a name="Footnote_44" id="Footnote_44"></a><a href="#FNanchor_44"><span class="label">[44]</span></a> 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.</p></div> + +<table class="nowrap" summary="Table page 186-1"> + +<tr> +<th colspan="10" class="center">Sheet-iron pipes brazed.</th> +</tr> + +<tr> +<th colspan="3"> </th> +<th class="center padl1 padr1"><i>s.</i></th> +<th colspan="2" class="center padl1 padr1"><i>d.</i></th> +<th colspan="4"> </th> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1 narrow"><sup>1</sup>⁄<sub>4</sub></td> +<td class="left padr3">inch in diameter</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">4</td> +<td> </td> +<td class="center padl1 padr1">a foot</td> +<td rowspan="14" class="bt br bb narrow"> </td> +<td rowspan="14" class="left padl0 narrow">-</td> +<td rowspan="14" class="left wrappable">in 15<br />to 18<br />feet<br />lengths.</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>3</sup>⁄<sub>8</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">4</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">5</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>5</sup>⁄<sub>8</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">6</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>3</sup>⁄<sub>4</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">6</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td> </td> +<td class="left padl0 padr1"><sup>7</sup>⁄<sub>8</sub></td> +<td class="left padr3">ditto</td> +<td> </td> +<td class="right padl1 padr0">7</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">1</td> +<td> </td> +<td class="left padr3">inch, ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">7</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">1</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>4</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">9</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">1</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">10</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">1</td> +<td class="left padl0 padr1"><sup>3</sup>⁄<sub>4</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">11</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">2</td> +<td> </td> +<td class="left padr3">inch, ditto</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr0">1</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">2</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>4</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr0">4</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">2</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="left padr3">ditto</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr0">5</td> +<td> </td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td class="right padr0">3</td> +<td> </td> +<td class="left padr3">inch, ditto</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr0">6</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +</tr> + +<tr> +<td colspan="3" class="left padr3">Copper pipes brazed <sup>1</sup>⁄<sub>4</sub> inch</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">4</td> +<td> </td> +<td class="center padl1 padr1">per foot</td> +<td colspan="3"> </td> +</tr> + +<tr> +<td colspan="3" class="left padr3">Ditto, ditto, ditto <sup>3</sup>⁄<sub>8</sub> inch</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr0">5</td> +<td class="left padl0 padr1"><sup>1</sup>⁄<sub>2</sub></td> +<td class="center padl1 padr1">ditto</td> +<td colspan="3"> </td> +</tr> + +<tr> +<td colspan="10" class="left">Gas-light cockspur burners with stop-cock 2s 6d to 3s 6d</td> +</tr> + +<tr> +<td colspan="10" class="left">Argand’s lamps, with glass-holders, from 3s to 4s 6d</td> +</tr> + +</table> + +<table class="nowrap notop" summary="Table page 186-2"> + +<tr> +<td class="left padr3">Cast-iron retorts, weighing 7 cwt. at 15s 6d per cwt</td> +<td class="right padr1 padl1">£5</td> +<td class="right padl1 padr1">8</td> +<td class="right padl1 padr1">6</td> +</tr> + +<tr> +<td class="left padr3">Mouth-piece for ditto, compleat</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr1">14</td> +<td class="right padl1 padr1">8</td> +</tr> + +<tr> +<td class="left padr3">Cast-iron door frames for retort furnace</td> +<td class="right padl1 padr1">1</td> +<td class="right padl1 padr1">0</td> +<td class="right padl1 padr1">0</td> +</tr> + +<tr> +<td colspan="4" class="left">Furnace bars 10s. per cwt.</td> +</tr> + +<tr> +<td colspan="4" class="left">Sheet iron for gazometer (No. 23) 24s. per cwt.</td> +</tr> + +<tr> +<td colspan="4" class="left">Gazometer chains, 5d per lb.</td> +</tr> + +<tr> +<td colspan="4" class="left">Ballance weights [Plates] for gazometer, 9l 10s per ton.</td> +</tr> + +<tr> +<td colspan="4" class="left">Cast-iron cistern plates</td> +</tr> + +<tr> +<td colspan="4" class="left">----------------------- smaller size for lime machine, 18l per ton.</td> +</tr> + +<tr> +<td colspan="4" class="left">----------------------- middling size for tar cistern, 16l ditto</td> +</tr> + +<tr> +<td colspan="4" class="left">----------------------- largest size for gazometer cistern 14l ditto</td> +</tr> + +</table> + +<table class="nowrap notop" summary="Table page 186-3"> + +<tr> +<td class="left">Cast-iron flanch pipes</td> +<td class="right padl1 padr0">2</td> +<td class="center narrow padl0 padr0">-</td> +<td colspan="2" class="left padl0 padr1">inch diameter, at</td> +<td class="right padr1">5s</td> +<td> </td> +<td class="left padl1 padr1">per yd. in</td> +<td class="right padr1">6</td> +<td class="left">feet lengths</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">3</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">6s</td> +<td> </td> +<td class="center">ditto</td> +<td class="right padr1">6</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">4</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">8s</td> +<td class="right padr1">6d</td> +<td class="center">ditto</td> +<td class="right padr1">9</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">5</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">10s</td> +<td> </td> +<td class="center">ditto</td> +<td class="right padr1">9</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">6</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">12s</td> +<td> </td> +<td class="center">ditto</td> +<td class="right padr1">9</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">7</td> +<td colspan="3" class="center">ditto</td> +<td class="right padr1">13s</td> +<td class="right padr1">6d</td> +<td class="center">ditto</td> +<td class="right padr1">9</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">8</td> +<td rowspan="4" class="bt br bb narrow"> </td> +<td rowspan="4" class="left padl0 narrow">-</td> +<td rowspan="4" colspan="4" class="left">11l. 5s. per ton</td> +<td rowspan="4" class="right padr1">9</td> +<td rowspan="4" class="center">ditto</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">9</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">10</td> +</tr> + +<tr> +<td class="center">ditto</td> +<td class="right padl1 padr0">11</td> +</tr> + +</table> + +<table class="nowrap notop" summary="Table page 186-4"> + +<tr> +<td class="left"><sup>1</sup>⁄<sub>2</sub> inch nuts, screws and washers to put iron pipes together</td> +<td class="right padl1 padr1">7d.</td> +<td class="center">per lb</td> +</tr> + +<tr> +<td class="left"><sup>5</sup>⁄<sub>8</sub> ditto</td> +<td class="right padl1 padr1">7d.</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="left"><sup>3</sup>⁄<sub>4</sub> ditto</td> +<td class="right padl1 padr1">6d.</td> +<td class="center">ditto</td> +</tr> + +<tr> +<td class="left">English bar-iron</td> +<td class="right padl1 padr1">13l.</td> +<td class="center">per ton</td> +</tr> + +<tr> +<td class="left">Best, ditto</td> +<td class="right padl1 padr1">18l.</td> +<td class="center">ditto</td> +</tr> + +</table> + +<p class="center fsize150"><em class="italic">FINIS.</em></p> + +<div class="figcenter"><a name="Plate6" id="Plate6"></a> +<img src="images/illo208.jpg" alt="Gasometer frame and pipe connectors" width="364" height="600" /> +<p class="largeimg"><a href="images/lg208.jpg">Larger image</a> (345 kB)</p> +</div> + +<div class="figcenter"><a name="Plate7" id="Plate7"></a> +<img src="images/illo210.jpg" alt="Gas works" width="600" height="499" /> +<p class="largeimg"><a href="images/lg210.jpg">Larger image</a> (302 kB)</p> +</div> + +<div class="tnbottom"><a name="TN" id="TN"></a> + +<h2>Transcriber’s notes</h2> + +<p>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.<br /> +The errata have already been incorporated in the text; the error mentioned as occurring on page 24 actually occurs on page 22.<br /> +The original language, including inconsistencies in spelling, hyphenation, punctuation, formatting, etc. has been retained, except as mentioned below.<br /> +The e-reader cover image has been created for this project, and is placed in the public domain.<br /> +Unclear parts of the text have been checked against the on-line copy of this book of the Eidgenssische Technische Hochschule Zrich.<br /> +Fractions like <sup>1</sup>⁄<sub>2</sub> and 1-10th have both been retained.<br /> +Page 90, Van Dieman, Troostwyck: Jan Rudolph Deiman and Adriaan Paets van Troostwijk.</p> + +<p>Changes made to the text:<br /> +Obvious punctuation and typographical errors have been corrected silently.<br /> +Some footnotes, tables and illustrations have been moved; some tables have been re-arranged.</p> + +<p>Other changes:<br /> +Page 23: any surfaces changed to any surface<br /> +Page 26: opening or shuting changed to opening or shutting<br /> +Page 47: A New changed to A new<br /> +Page 48: trafic changed to traffic; footnote [10]: corporated changed to incorporated (cf. errata)<br /> +Page 53: This combustion changed to The combustion (cf. errata)<br /> +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)<br /> +Page 67: 1250 + 2 = 2500 changed to 1250 × 2 = 2500<br /> +Page 69: Mr. <span class="smcap">Lee</span> changed to “Mr. <span class="smcap">Lee</span> for consistency<br /> +Page 72: closing quote mark added to letter<br /> +Page 96: pure coal- changed to pure coal-gas<br /> +Page 102: sub acetate changed to sub-acetate<br /> +Page 118: ball 6 changed to ball <i>b</i><br /> +Page 119: <i>e</i>, are changed to <i>e</i> <i>e</i>, are<br /> +Page 125: 180 degree changed to 180 degrees (cf. errata); footnote [28]: may he compleatly changed to may be compleatly<br /> +Page 131: and make changed to and makes<br /> +Page 132: coal changed to coal-tar (cf. errata)<br /> +Page 158: Nortou Falgate changed to Norton Falgate; a about changed to about<br /> +Page 165, table: 10,509 changed to 10,500.</p> + +</div><!--tnbottom--> + + + + + + + + +<pre> + + + + + +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-h.htm or 44567-h.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 Lam 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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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: ASCII + +*** START OF THIS PROJECT GUTENBERG EBOOK A PRACTICAL TREATISE ON GAS-LIGHT *** + + + + +Produced by Chris Curnow, Harry Lame 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 LINNAEN 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_ squared : Q [::] + _b_ squared : (_b_ squared + Q)/_a_ squared = 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_ squared + Q)/_a_ squared (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 deg. 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 deg., 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 x 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 L 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 L 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 L 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 L 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 _naivete_ 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 deg. 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 deg. + 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. + + L. 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 + --------- + L 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 L5 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 Eidgenoessische Technische Hochschule Zuerich. + +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 x 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.txt or 44567.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 Lame 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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