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diff --git a/old/63117-0.txt b/old/63117-0.txt deleted file mode 100644 index a4628d0..0000000 --- a/old/63117-0.txt +++ /dev/null @@ -1,8241 +0,0 @@ -The Project Gutenberg EBook of Description of the Process of Manufacturing -Coal Gas, for the Lighting of Streets House, by Frederick 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/license - - -Title: Description of the Process of Manufacturing Coal Gas, for the Lighting of Streets Houses, and Public Buildings etc. - -Author: Frederick Accum - -Release Date: September 4, 2020 [EBook #63117] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK DESCRIPTION OF THE PROCESS *** - - - - -Produced by deaurider, Harry Lamé and the Online Distributed -Proofreading Team at https://www.pgdp.net (This file was -produced from images generously made available by The -Internet Archive) - - - - - - - - Transcriber’s Notes - - Text printed in italics has been transcribed _between underscores_, - bold face text =between equal signs=. ~Text between tildes~ represents - blackletter text, ^{text} represents superscript text. Small capitals - have been replaced with ALL CAPITALS. - - More Transcriber’s Notes may be found at the end of this text. - - -[Illustration: _Pl. II._ - -_Accums’, Description of Gas Works._ - -_to Face Title._ - -_Mulholland Del^{t}._ - -_W. Read, Sculp^{t}. Maiden Lane, Covent Garden._ - -GAS LIGHT APPARATUS, - -_Erected by Order of Government at =THE ROYAL MINT=, by Fredc^{k}. -Accum._] - - - - - DESCRIPTION - OF - THE PROCESS OF MANUFACTURING - COAL GAS, - FOR THE LIGHTING OF STREETS HOUSES, AND PUBLIC BUILDINGS, - WITH - ELEVATIONS, SECTIONS, AND PLANS - _OF THE MOST IMPROVED SORTS OF APPARATUS_ - NOW EMPLOYED AT THE - ~Gas Works in London,~ - AND THE PRINCIPAL PROVINCIAL TOWNS OF GREAT BRITAIN; - _Accompanied with comparative Estimates, exhibiting the most - Economical Mode of procuring this species of Light_. - - [Illustration: _Plate I._] - - _WITH SEVEN PLATES._ - - BY FREDRICK ACCUM, - _OPERATIVE CHEMIST_, - - Lecturer on Practical Chemistry, on Mineralogy, and on Chemistry - applied to the Arts and Manufactures; Member o£ the Royal Irish - Academy, Fellow of the Limnæan Society, Member of the Royal Academy of - Sciences of Berlin, &c. &c. - - ~London.~ - - PRINTED FOR THOMAS BOYS. N^{o}. 7. LUDGATE-HILL. (FROM N^{o}. 3, - PATERNOSTER ROW) - - MDCCCXIX. - - - - -PREFACE. - - - _Compton Street, Soho._ - -The extraordinarily rapid progress which the recent invention of -lighting with coal gas has made in this country, is perhaps without a -parallel in the history of the useful arts. - -It was an invention not exempted from the misfortune common to all -innovations on established practises, of encountering opposition, but it -had the fortune common to few, of obtaining an almost instantaneous -triumph. - -A single exhibition of the gas lights in actual use was sufficient to -determine the public judgment in favour of the new mode of illumination; -to see was in this case, indeed to believe. - -The legislature responsive to the popular voice, and fortified in its -responsibility, by the results of special enquiries which were ordered -to be made into the merits of the invention, and in which I had the good -fortune to be professionally engaged, gave the most liberal and decided -encouragement to its adoption. - -Capital, often wanting even in this opulent country for undertakings of -magnitude, came to the promotion of the new art of procuring and -distributing light in overflowing abundance; and already ere many years -are elapsed, such has been the rapidity with which the gas light -illumination has advanced, that there is not a city and scarcely a town -of any note in Great Britain, in which the art of lighting by means of -gas, has not been carried into effect, or in which active measures are -not in progress, to participate in the benefit of this important -discovery. - -When the art was yet in its infancy, I published a Treatise, containing -a description of the apparatus and machinery best calculated for -illuminating streets, houses, and public buildings, by means of coal -gas, with remarks on the utility, safety, and general nature of this new -branch of domestic economy, as far as then understood, and practised in -the metropolis. - -The universal avidity for information on the subject, more perhaps than -any particular merit in the work itself, produced a demand in this -country for four large impressions of this work, in the course of a few -years, and I have also had the satisfaction of finding that the Treatise -has been translated into the French, German, and Italian languages. - -Since this work was written, however, the art of manufacturing and -applying coal gas, has undergone so many material improvements, all -combining to bring it to a degree of simplicity, precision, and economy, -far surpassing every thing which the original mode of practice -exhibited, that I have felt I should be guilty of an injustice to the -constant demand which still exists for my former Treatise, had I not -made it my duty to publish the work I now present to the reader; -superseding altogether the former publication, but superseding it from -circumstances of necessity, and with a view to good, which I trust will -be found not illusory. - -The present treatise, as its title expresses, is intended to exhibit the -superior process of manufacturing coal gas now employed in the -metropolis and the provincial towns of Great Britain, and to lay before -the reader the elevations, sections, and plans of the improved Gas Light -machinery, which has stood the test of practice, and is now in action at -the most celebrated Gas Light Establishments. - -In the first and second part of the Treatise, I have, as introductory -to the rest, given a sketch of the chemical theory and production of Gas -Light. I have pointed out the leading objects of public and private -utility, to which the art of lighting with gas has been, or remains to -be applied: and added such other facts and observations as may serve to -remove all doubt in the minds of the reader as to the important benefit -which this country in particular, and the world at large, have gained by -this discovery. - -In the third part I have stated the maximum quantities of gas obtainable -in the large way, from different kinds of coal. - -In the fourth part, I have given a description of all the various forms -and dimensions which the distillatory vessels or retorts have -successively assumed, as well as of the improvements that have been made -in the mode of setting the retorts, with a view to saving them from -undue deterioration, and preventing any improvident waste of fuel. I -have here given a particular account of the distillatory apparatus now -used at the most celebrated gas works in the metropolis. - -The fifth and sixth parts, lead the reader considerably further into a -knowledge of the economy and practice of this art. They contain an -account of a great variety of experiments which have been pursued on a -large scale, in order to ascertain the most profitable mode of -employing the retorts, the differences of opinion which have existed -among practical men with respect to the degree of temperature fittest to -be applied, and the number of hours at a time during which the retorts -may most advantageously be kept in action, with the particular results -which the experiments instituted into these points have afforded; and -such other data, as will enable the reader to adopt that mode of -operation, which under every circumstance of locality will be found most -advantageous. - -The changes which have taken place with respect to the retorts, have -been before detailed in part fourth; but in order to give the -manufacturer a nearer insight into the superior advantages attending -retorts of the construction lately brought into use, I have given in -part seventh, a detailed description of the horizontal rotary retorts, -the application of which has led to a more economical, expeditious, and -easy method of manufacturing coal gas than heretofore practised. I have -distinctly pointed out the advantages which these retorts present, the -particular results they afford, and the method of applying them. - -The purification of coal gas forms the subject of part eighth. I have -compared here, the apparatus for purifying coal gas, as it was -originally constructed, with the improved machinery lately adopted, -showing the inefficacy and defects of the former, and the decided -superiority which belongs to the latter. - -The ninth part gives an account of the various improved gas holders -which have been invented, and now are in action at the most recent -establishments, for the purpose of storing large quantities of gas. The -improvements that have been made in this department of the Gas Light -machinery, are particularly valuable and have contributed more perhaps -than any other, to lessen the expence of manufacturing gas for -commercial purposes. - -In the tenth part, I have given a description of an entirely new -machine, called the gas-metre, or self-acting guage, lately adopted at -the Birmingham, Chester, and other gas works, which measures and -registers the quantity of gas manufactured in any given time, from any -given quantity of coal, or consumed during any period, by any number of -burners or lamps. The great services which such a machine must render -both to the manufacturer and consumer of gas, are particularly pointed -out, and illustrated to the manufacturer, by serving as a complete check -on his workmen as to the quantity of work that ought to be performed, -and to the consumer, as an exact measure of the quantity of gas he -receives, and ought to pay for. - -The eleventh part is appropriated to the description of another -apparatus, called the governor, also of recent invention, and now in use -at numerous establishments. The design of this machine is, to regulate -the pressure of the gas, before it enters into the mains, the importance -of which must be sufficiently manifest. I have also pointed out the -application of this apparatus for regulating the magnitude of the flames -of gas burners and lamps. - -The twelfth part treats on gas mains and branch pipes, I have here -stated the rules and practical proceedings necessary to be observed, for -applying and distributing gas pipes to the greatest advantage. - -The most efficient method of introducing the gas to the interior of -houses, forms the subject of part thirteen. All the necessary -instructions are here given to workmen, for adapting the gas pipes, and -insuring success at the least cost, under every variety of -circumstances. - -The fourteenth part gives an account of the illuminating power of coal -gas--the quantity of gas consumed in a given time, by different kinds of -gas burners and lamps, the relative cost of gas, tallow, and oil lights -of different intensities, and the most improved method employed for -ventilating apartments lighted by gas. - -In the fifteenth and sixteenth parts, I have added an account of the -manufacture of carburetted hydrogen gas, from coal tar, vegetable tar, -and oil, with such other observations as may enable the reader to form a -proper estimate of the comparative advantage of manufacturing gas from -oil, or tar, under certain circumstances. I have here also given an -account of the manufacture of carbonate of ammonia, as now practised, -from the ammoniacal liquor obtained in the Gas Light process, and of the -manufacture of other saleable products obtainable from coal, namely; -pitch, coal tar, and oil. - -In conclusion I have to observe that my object throughout has been to -make the work a compendium of all the best information which the -practice of the art down to the present moment has been able to afford, -embodying a great number of data, with which I have been obligingly -favoured by gentlemen, the most practically versant in the art, and for -which I beg they will individually accept this public expression of my -thanks, and obligations, as well as the results which my own labours in -this department, neither few, nor inconsiderable have furnished. - -To supply the reader with a work of practical utility in a most -valuable, and growing branch of national economy has been my object; and -I need scarcely add, that the suffrages of the public to the zeal and -industry at least with which I have endeavoured to obtain that object, -will be a source of infinite satisfaction. - - FREDRICK ACCUM. - - _LONDON, 1819._ - - - - -CONTENTS. - - - PART I. - - PAGE - - GENERAL NATURE AND ADVANTAGES OF THE ART OF PROCURING LIGHT, BY - MEANS OF CARBURETTED HYDROGEN, OR COAL GAS 1 - - - PART II. - - OUTLINE OF THE NEW ART OF PROCURING LIGHT BY MEANS OF COAL GAS, - AND THEORY OF THE PRODUCTION OF GAS LIGHTS 33 - - - PART III. - - CLASSIFICATION OF PIT COAL, AND MAXIMUM QUANTITY OF GAS, - OBTAINABLE FROM DIFFERENT KINDS OF COAL 41 - - - PART IV. - - FORM AND DIMENSIONS OF THE RETORTS ORIGINALLY EMPLOYED FOR - MANUFACTURING COAL GAS 51 - - APPLICATION OF HEAT--FLUE PLAN ORIGINALLY ADOPTED 59 - - REPORT ON A COURSE OF OPERATIONS, MADE WITH SETS OF 66, OF 30, OF - 116, AND OF 64 RETORTS, WORKED ON THE FLUE PLAN 61 - - OVEN PLAN LATELY ADOPTED 67 - - DESCRIPTION OF THE RETORT OVEN 69 - - - PART V. - - DIFFERENCE IN THE QUANTITY OF GAS EVOLVED DURING DIFFERENT - PERIODS OF THE DISTILLATORY PROCESS, AND ECONOMICAL - CONSIDERATIONS RESULTING THEREFROM IN THE MANUFACTURE OF COAL GAS 77 - - EXPERIMENTS WITH 18 CYLINDRICAL RETORTS, CONTAINING ONE CHALDRON - OF COAL 80 - - EXPERIMENT WITH THIRTY-SIX PARALLELOPIPEDAL RETORTS, EACH - CONTAINING TWO BUSHELS OF COAL 81 - - REPORT ON A COURSE OF EXPERIMENTS MADE TO ASCERTAIN THE - COMPARATIVE ECONOMY OF MANUFACTURING EVERY WEEK, 857,667 CUBIC - FEET OF GAS, BY MEANS OF CYLINDRICAL RETORTS VARIOUSLY WORKED 84 - - - PART VI. - - TEMPERATURE BEST ADAPTED FOR WORKING CYLINDRICAL RETORTS 94 - - ANNUAL CREDITOR AND DEBTOR ACCOUNT OF MANUFACTURING DAILY, FROM - 50,000 TO 102,000 CUBIC FEET OF GAS, AT THE PRICE WHICH COAL - BEARS IN THE METROPOLIS, THE OPERATION BEING COMMENCED WITH NEW - RETORTS, AND THE RETORTS BEING LEFT IN A FIT WORKING STATE 97 - - COMPARATIVE FACILITY WITH WHICH THE DECOMPOSITION OF DIFFERENT - SPECIES OF COAL IS EFFECTED 106 - - - PART VII. - - HORIZONTAL ROTARY RETORTS, LATELY BROUGHT INTO USE FOR - MANUFACTURING COAL GAS 110 - - DESCRIPTION OF THE HORIZONTAL ROTARY RETORTS AT THE ROYAL MINT 112 - - ACTION AND MANAGEMENT OF THE HORIZONTAL ROTARY RETORTS 120 - - ADVANTAGES OF THE METHOD OF MANUFACTURING COAL GAS BY MEANS OF - HORIZONTAL ROTARY RETORTS 124 - - DIRECTIONS TO WORKMEN WITH REGARD TO THE MANAGEMENT OF HORIZONTAL - ROTARY RETORTS 134 - - - PART VIII. - - PURIFYING APPARATUS, OR LIME MACHINE 140 - - LIME MACHINE ORIGINALLY EMPLOYED FOR THE PURIFICATION OF COAL GAS 141 - - LIME MACHINE LATELY ADOPTED 149 - - TEST APPARATUS, FOR CERTIFYING THE PURITY OF COAL GAS, AND THE - PROPER MANNER OF WORKING THE LIME MACHINE 157 - - BEST METHOD OF PREPARING QUICK-LIME FOR THE PURIFICATION OF COAL - GAS 161 - - - PART IX. - - GAS HOLDER 164 - - GAS HOLDER AS ORIGINALLY EMPLOYED 165 - - GAS HOLDER WITH GOVERNOR, OR REGULATING GUAGE, LATELY BROUGHT - INTO USE 169 - - GAS HOLDER WITH GOVERNOR OR REGULATING GUAGE AT THE CHESTER GAS - WORKS 175 - - GAS HOLDER WITH GOVERNOR OR REGULATING GUAGE AT THE BIRMINGHAM - GAS WORKS 177 - - REVOLVING GAS HOLDER AT THE WESTMINSTER GAS WORKS 181 - - RULE FOR FINDING THE CAPACITY OF A REVOLVING GAS HOLDER OF GIVEN - DIMENSIONS 185 - - COLLAPSING GAS HOLDER 185 - - RULE FOR FINDING THE CAPACITY OF A COLLAPSING GAS HOLDER OF GIVEN - DIMENSIONS 195 - - RECIPROCATING SAFETY VALVE 196 - - - PART X. - - GAS METRE, OR SELF-ACTING GUAGE, WHICH MEASURES AND REGISTERS, IN - THE ABSENCE OF THE OBSERVER, THE QUANTITY OF GAS PRODUCED IN A - GIVEN TIME, FROM ANY GIVEN QUANTITY OF COAL, OR CONSUMED DURING A - GIVEN PERIOD, BY ANY NUMBER OF BURNERS OR LAMPS 200 - - DESCRIPTION OF THE GAS METRE AT THE ROYAL MINT GAS WORKS 214 - - RULE FOR CALCULATING THE WEIGHT, WHICH A GAS METRE OF GIVEN - DIMENSIONS, WILL RAISE, TO A GIVEN HEIGHT, IN A GIVEN TIME 220 - - GAS HOLDER VALVE 221 - - SIPHON, OR WATER RESERVOIR 221 - - - PART XI. - - GOVERNOR OR REGULATING GUAGE 225 - - DIRECTIONS TO WORKMEN FOR FIXING THE GOVERNOR AND GAS METRE 229 - - - PART XII. - - GAS MAINS AND BRANCH PIPES 239 - - WEIGHT OF CAST IRON GAS MAINS OF DIFFERENT LENGTHS AND BORES 251 - - - PART XIII. - - GAS LAMPS AND BURNERS 253 - - DIRECTIONS TO WORKMEN, FOR ADAPTING GAS PIPES TO THE INTERIOR OF - HOUSES 258 - - - PART XIV. - - ILLUMINATING POWER OF COAL GAS, AND QUANTITY OF GAS CONSUMED IN A - GIVEN TIME, BY DIFFERENT KINDS OF BURNERS, AND GAS LAMPS 269 - - - PART XV. - - GAS FROM COAL TAR 282 - - GAS FROM OIL 289 - - - PART XVI. - - OTHER PRODUCTS OBTAINABLE FROM COAL, NAMELY: - - COAL TAR 298 - - COAL OIL 300 - - PITCH 302 - - AMMONIACAL LIQUOR 303 - - MANUFACTURE OF CARBONATE OF AMMONIA FROM THE AMMONIACAL LIQUOR 303 - - MANUFACTURE OF MURIATE OF AMMONIA FROM THE AMMONIACAL LIQUOR 307 - - DESCRIPTION OF THE PLATES 315 - - INDEX TO THE WORK 321 - - LONDON PRICE LIST OF THE MOST ESSENTIAL ARTICLES EMPLOYED IN THE - MANUFACTURE AND APPLICATION OF COAL GAS 331 - - - - -ADVERTISEMENT. - - - The author of this work respectfully informs the public, that they may - be furnished with estimates, and plans for the building of Gas Works, - particularly adapted to the circumstances of the places where they are - to be established, and that he proposes to superintend the erection of - the works. - - Mr. Accum also engages to supply the whole of the Gas Apparatus ready - for immediate use, and to guaranty its efficient performance. - - Or he will contract with any committee, directory, or public company, - for Lighting with Gas, any Town, Manufactory, or Building, upon - whatever scale of magnitude, for an annual specific sum. - - Of the qualifications for the services which he thus proffers, he - would speak with diffidence. Such proofs as he is able to offer of - them, are to be found in the work here laid before the reader, beyond - which he would add no more than the flattering testimony of - approbation, with which his labours have been honoured, in having been - selected by HIS MAJESTY’S GOVERNMENT to plan and erect the GAS WORKS - at the ROYAL MINT, and since entrusted with the active management and - superintendance of that establishment. - - _Compton Street, Soho, - - May 28, 1819._ - - The following particulars are required to be stated by those who are - desirous of receiving estimates, concerning the comparative economy of - applying coal gas as a substitute for oil, wax, or tallow light. - - 1. A plan of the place to be lighted with Gas, drawn to a scale not - less than one tenth of an inch, to ten feet. The design must exhibit - the particular spot, where the Machinery is to be erected. - - 2. The kind of gas lights required, namely; whether the lights shall - be equal in illuminating power to one, or more tallow candles of a - given weight, or equal to an argand lamp. - - 3. The number of lights. - - 4. The average time the lights are to burn, throughout the year. - - 5. The average price of coal, and rate of workmen’s wages, at the - place where the light is wanted. - - - - - AN - ACCOUNT - OF THE - PROCESS OF MANUFACTURING - ~Coal Gas~. - - - - -PART I. - - -_General Nature and Advantages of the art of procuring Light, by means -of Carburetted Hydrogen, or Coal Gas._ - -The new art of lighting houses, streets and manufactories, with -carburetted hydrogen, or coal gas, is one of those modern discoveries on -which the admirers of science and the inhabitants of this country in -particular, have greater reason to congratulate themselves, than any -other invention or discovery of the present age. - -This art is so wonderful and important, it speaks so forcibly by the -effects it has already produced, that it cannot fail to increase the -wealth of the nation by adding to the number of internal resources, as -long as coal continues to be dug in this island from the bowels of the -earth. - -For if we distribute the catalogue of human wants which a civilized -state of society has introduced, the production and supply of artificial -light, holds next to food, clothing and fuel, the most important place. -We might indeed exist without it, but how large a portion of our lives -would in that state be condemned to a state little superior in efficacy -to that of the animals around us. - -If we could for a moment suppose the privation of artificial light, -during the absence of the Sun, 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 power -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 respect, 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 procuring light, a train of ideas -has slightly been hinted at, which cannot fail to show its magnitude and -importance. - -The progress of the new art of lighting houses, streets and public -buildings, by means of the inflammable gas obtainable from coal, has -been within these few years uncommonly rapid. The number of gas-lights -already in use in the metropolis alone, amounts to upwards of fifty-one -thousand. The total lengths of mains in the streets through which the -gas is conveyed from the gas-light manufactories into the houses, now -measures two hundred and eighty-eight miles. - -The gas-light illumination has also spread far and wide through the -country. Establishments for the supply of the new lights are carried on -at Edinburgh, Glasgow, Liverpool, Bristol, Bath, Cheltenham, Birmingham, -Leeds, Manchester, Exeter, Chester, Macclesfield, Preston, -Kidderminster, and in many other towns and places of Great Britain. - -Every body is now convinced that pitcoal is capable of furnishing light -superior to that obtained from oil, wax, or tallow. The public attention -is awakened to the new value of coal, and will not rest till the art of -lighting with gas is pushed to the utmost of its extent. - -In order to arrive at a full and accurate knowledge of the many -advantages attending the application of carburetted hydrogen or coal -gas, as a substitute for candles or lamps, it may be necessary, -especially for the information of those readers who have never -personally witnessed this mode of illumination, to take a brief -preliminary view of some of the leading objects of public and private -utility, to which this mode of procuring and distributing light may be -applied, and of the extent to which it is entitled to national -encouragement. - -The chief advantages attending the use of gas, are superiority and -uniformity of light, saving of labour, cleanliness, safety and -cheapness. - -It must be difficult for a person wholly unacquainted with this art, to -imagine with what facility and neatness gas-lights are managed. The gas -being collected in a reservoir, is conveyed by means of tubes, which -branch out into smaller ramifications, until they terminate at the -places where the lights are wanted. The extremities of the branching -tubes are furnished with burners, having small apertures out of which -the gas issues with a certain velocity corresponding to its degree of -pressure. Near the termination of each tube, there is a stopcock, or -valve, upon turning which when light is required, the gas instantly -flows out in an equable stream. There is no noise at the opening of the -valve, no disturbance in the transparency of the atmosphere; the gas -instantly bursts on the approach of a lighted taper into a peculiarly -brilliant, soft and beautiful flame; it requires no trimming or -snuffing to keep the flame of an equal brightness. Like the light of the -Sun itself, it only makes itself known by the benefit and pleasure it -affords. - -The gas flame is entirely free from smell. The gas itself has a -disagreeable odour before it is burnt, and so has the vapour of wax, -tallow and oil, as it comes from a candle or lamp newly blown out. This -concession proves nothing against the flame of gas, which is perfectly -inodorous. - -The gas-light flame is perfectly steady; a benefit which persons -accustomed to read or write by candle-light, are particularly capable of -appreciating. With the other modes of illumination we have never the -light of the same intensity for two minutes together, independent of -that unpleasant dancing unsteady flame which is so harassing to the -sight. - -The size, form and intensity of the gas flame, are regulated by simply -turning the stop-cock which admits the gas to the burner or lamp. The -flame 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 lights of this -description are in nurseries, stables, warehouses, and chambers of the -sick. From the facility with which the gas flame can be conveyed in -almost any direction, from the diversified size and shape which it can -be made to assume, there is no kind of light so well adapted for -ornamental illumination. - -The flame of coal gas is of a pure white colour, and of a body full and -compact. In large masses, it becomes of the same flickering character -which is common to all flames of large dimensions, and is owing to the -agitation of the surrounding heated atmosphere. - -The saving of labour connected with the employment of gas-light, may -seem on a small scale to be trifling; but when it is considered that in -large manufactories, it is not unusual to find several persons employed -for no other purpose than trimming the lamps or setting and snuffing the -candles of the establishment, the advantage gained on this head by the -use of a species of light which require no sort of attention whatever, -cannot but appear very considerable. - -The cleanliness of the gas-lights is also a consideration of no small -importance, they are attended with none of that spilling of oil, and -dropping of grease, which makes the employment of oil-lamps and candles -so injurious in many warehouses, shops and private dwellings. - -The flame of a gas-light compared in point of brilliancy to that of a -candle, is as the flame of a common oil lamp, compared to the flame of a -lamp of Argand. The difference between a street, on the night of a -general illumination, and any other night when the street is under the -dull glimmering light of the ordinary oil lamps, is scarcely more -remarkable, than the difference between a street lighted by gas, and one -lighted by oil. While the ordinary oil lamps may be said merely to serve -the purpose of making “_darkness visible_,” the gas-lights really dispel -the dominion of night, and diffuse a body of light so wide-spreading and -intense, as almost to rival the clearest moonshine. - -The same brilliancy which makes the gas-lights of such utility out of -doors, in lighting the streets, has been found of equal advantage in -illuminating the interior of private dwellings, and large public -buildings, such as churches, and theatres, &c. From a cluster of -gas-lights, fewer by one-half than the number of oil lamps and candles -required for lighting up a public edifice of this description in the -most ordinary manner, a body of light is furnished which diffuses -through the whole, a degree of mellow clearness which is not to be -attained by the greatest number of oil lamps, or candles, which a due -regard to respiration will admit of being employed. As examples of this, -we have only to name the public theatres of the metropolis, all of which -are lighted with gas, and in a manner which excites universal -admiration. - -It may perhaps be imagined that with a substance so inflammable, and -amidst the blaze of resplendent flame which produces such beautiful -effects, there is a peculiar risk of accidents by fire, but so far is -this from being the case, that gas-lights are the safest of all lights. -No danger can arise from these lights in any way, but what is common to -candle lights and lamps of all kinds, and is the fault of none of them. -The gas-lights are in fact a great deal less hazardous. There is no risk -of those accidents which often happen from the guttering of candles, -from sparks being detached, 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. And further, at any time by shutting the main -tube which conveys the gas to the burners and lamps, all the lights in -the house can be immediately extinguished. In short, where gas is used, -the master of the house, when he has turned the main stop-cock which -conveys the gas into the collateral branch pipes, may retire to rest -free from any of those apprehensions, which before harassed him, lest a -candle might have been left burning, of lest the accidental dropping of -a spark might become the cause of enveloping himself and family in -destruction. - -But the best proof of the great safety of the new lights is, that -notwithstanding upwards of fifty-one thousand gas-lamps burn nightly in -London, we have not heard of a single accident occasioned by them, -though the lamps and burners are generally carelessly managed, while we -have too often occasion to lament the effects arising from sparks of -candles, or carelessness in snuffing them. - -Hence the fire-insurance-offices engage to insure manufactories and -public works, at a less premium, where gas is used, than when lighted by -other means. - -The excessive expence of insurance, arising from the numerous candles -employed in most of the first-rate manufacturing establishments, 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 -considerations 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. - -We have as yet only adverted to the application of gas in the more -ordinary cases where light is wanted, but among other special purposes -to which gas-lights may be applied, it would be improper to overlook the -peculiarly advantageous use which may be made of them in the supplying -of light-houses. From the splendour and distinguishing forms which the -gas-light flame is capable of assuming, nothing can possibly be better -calculated for such a purpose; and in point of economy, the employment -of it would be attended with a saving of at least one half of the -ordinary expence of oil lights. By means of a single furnace, as much -gas may be produced in three hours, as will furnish during the longest -winter night, a flame of greater brilliancy than is now furnished by any -lighthouse in Britain, or indeed in the world. The body of flame may be -increased to any size, merely by increasing the number of burners; and -whatever may be the magnitude of the flame, it will continue to burn, -without becoming in the least clouded by smoke, or the reflectors being -in the least obscured. Should these considerations lead, as it is to be -hoped they will, to the actual employment of gas in the lighthouses -around the British islands, it will readily occur, that in proportion as -the gas would be found attended with less expense than the present mode -of lighting by oil, it would enable the commissioners for light-houses, -out of the surplus means which would be thus placed at their disposal, -to multiply the number of lighthouses, and thus to add most essentially -to the security of British navigation. Nor is it in the case of maritime -signal-lights alone, that the use of gas is applicable, by its superior -efficacy and cheapness. The saving of expences to the country which -would be effected by the substitution of coal gas, for oil and tallow in -these and other public establishments, is a consideration which cannot -be too much pressed on public attention. The annual expenditure for -lighting the barracks of Great Britain alone, is said to fall little -short of fifty thousand pounds; for less than one half of which sum, -they might be lighted by means of gas much better, and a great deal more -safely. Some idea may be formed from the practical saving in this -department--how great might be the total saving, were this new mode of -lighting adopted in all our national establishments. - -In the case of the public arsenals, however, the saving from the -employment of coal gas is a consideration of far inferior importance to -the _superior security_ attending it. On the preservation of the stores -which they contain may depend in a time of war the whole chance of -success against the enemy nor can any body who has lived in this -country at such a time have forgot the feverish alarm with which the -people have frequently seen this security endangered by accidents -arising from the use of moveable lights. Were coal gas exclusively -employed in such establishments, the fixed position which can be given -to the burners, and the absence of all danger from sparks must give a -degree of security to those places from fire, far beyond what they at -present possess, even when superintended with the greatest possible -caution and fidelity. - -The same remark is equally applicable to the government offices, public -libraries, museums, in short, to all public establishments where the -national value of the articles preserved is such that no _possible_ -means of increasing their security from destruction should be neglected. - -We have now to turn our attention to another general point of view in -which the introduction of lighting by gas is not less an object of -interest to the public; we allude to the application of gas as a means -of _heating_ as well as lighting. Mr. Maiben[1] was the first who -directed the attention of the public to this subject; he ascertained -that gas from coal gives nearly the same heat when put into combustion, -which is yielded by a third part of the coal from which it is extracted. -In other words, it has been found that a quantity of fuel giving a -particular degree of heat, may be employed so as to produce at the same -time another substance yielding nearly an equal degree of heat in a -different and more manageable form; a form in which it can be preserved -for any length of time, divided into any portions, distributed in any -direction, consumed in an open fire-place, or in a stove concealed in -any shape; a form in which the flame may issue equally well from iron or -from stone-ware, be instantly lighted up and instantly extinguished, be -made to burn as long or as short a time as may suit us, and in any -degree of intensity between the most animating and brilliant blaze and -its total extinction; be extinguished in one room, and the next moment -lighted up in any other; in short such a form, that by one proper -arrangement from the beginning, with the same portion of fuel, we may at -any time have the command of a chearful fire, an adequate and -comfortable warmth in any part of our dwelling to which we may have -occasion to move, as manageable, and in this way as portable, as the -taper by the touch of which it is kindled. To those who have been -accustomed to see before them a solid mass of burning fuel, this gas -flame may at first have the less satisfactory appearance of a fugitive -blaze which we perceive nothing to support. But its uniformity and -permanence will soon banish this impression, while it is attended with -other advantages not inconsiderable with respect either to comfort or -convenience. There are no coals to be carried in, no ashes to be carried -out; there is no blowing, no sweeping of cinders, no dust, no -interruption of servants; there is no excessive heat in one stage, no -sudden damping at another: we have the choice of any temperature, and -which we can regulate with the utmost ease. The fire itself is lively -and pleasant to the eye: inclosed in transparencies it receives a degree -of splendour not easily imagined. Numerous applications of gas, as a -source of heat for airing rooms, and other purposes, have already been -adopted. It is used in kitchens for keeping meat warm, and for boiling -water; in store rooms, in picture galleries, in libraries, for -maintaining them at an equal temperature. By copper-plate printers, it -is used for warming their plates; and by jewellers and other artists, -for soldering. - - [1] _A Statement of the advantages to be derived from coal gas._--p. - 42. - -It remains further to be observed that the coal, by yielding gas and -other products, namely, tar, pitch, and ammoniacal liquor, is not -entirely lost. It produces, besides light, an excellent fuel, namely, -coke; and as a manufactory, or workshop, generally requires heating as -well as lighting, there is a gain both ways. The manufacturer, by -distilling his coal instead of burning it as it comes from the pit, -saves his candles and improves his fuel. One effort at the outset in -erecting a gas apparatus, will reduce his annual disbursement for those -two articles of prime necessity, much in the same manner, though in a -greater degree, as the farmer gains by building a thrashing machine and -laying aside the use of the flail. - -The coal is so far from being reduced in consequence of the gas-light -process, to an useless mass, that in many places immense quantities are -reduced to the state of coke for the purpose of rendering the coal a -better fuel than it was in its natural state; for coke gives a strong -and lasting heat. It is equally valuable for kitchen and parlour fires, -and still more as a necessary requisite in some important branches of -manufacture, so that in whatever quantity coke may be produced, it can -never want a good market. The demand for coke in this capital, since the -establishment of the gas-light works, has prodigiously increased. -Numerous taverns, offices, and public establishments, which heretofore -burnt coal, now use coke to the total exclusion of coal; and in almost -every manufactory, which requires both extensive lighting and heating, -gas and coke are now the means jointly employed. A coke fire emits a -very uniform and intense heat; it produces no sparks, and burns free -from soot and smoke; it requires no trouble in managing, and to those -who have the misfortune of being plagued with a smoaky chimney, affords -the only certain cure. - -Another valuable product is the tar which is deposited during the -production of the gas, this tar when rectified by a slight evaporation, -has become an article of commerce. Large establishments, both of coal -tar, coal oil, and pitch, are in full action, and the commodities which -they furnish have become in great demand. The ammoniacal liquor which -the gas-light process affords, has of late given rise to very important -branches of chemical manufacture, carried on upon a large scale. But as -the gas is at present supposed to be the only object in view, for the -sake of the light which it yields, the other products being only -accidentally connected with its extraction, let us leave the idea of -profit on them out of the question, and with the utmost latitude of -concession, require them only to stand as in part for a portion of the -coal employed in the process, we have still the gas, an article which -performs the functions of the oil, the tallow, or the wax for which it -is substituted; and to the price of which we have no need to call the -attention of those who make use of them. There remains only to be -opposed on the other side, the expence of the apparatus by which the gas -is to be prepared, and the lights maintained. From the materials and the -workmanship, with the interest of the capital sunk, the expence in the -first instance, must be very considerable. But where the quantity of -light must be great, even from cheap substances, or where, with a less -quantity of light, the substances from which it is derived must be of -the costliest kind; such is in either case the enormous expence of these -materials, that by superseding them and making every reasonable -allowance to the engineer who erects the gas apparatus, the sum it -costs, both principal and interest, is soon liquidated, leaving at last -a total saving, excepting the expence of accidental repairs, which, from -the durability of the materials employed, seldom exceeds a trifling sum. - -The principal expence in the pursuit of this new branch of civil and -domestic economy, is therefore, the dead capital employed in erecting -the machinery for obtaining and conveying the gas. The floating capital, -after the first cost incurred in erecting the apparatus, is -comparatively small; even if usurious interest is allowed for the first -cost of the apparatus, and its deterioration, the saving must always be -considerable, especially if the number of lights furnished are -comparatively in a small place. - -At the same time were we to offer 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 forty pounds. But when a street, or small neighbourhood is -required to be lighted the operation may be commenced with safety; the -sum required for erecting the apparatus, and the labour attending the -process, together with the interest of money sunk, will then soon be -liquidated by the light and other products. - -Individuals have accordingly engaged successfully in the distillation of -coal, and trade with advantage in the articles produced by the process. - -In like manner may the lighting of cities 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. - -The supplying of light to the street or parish lamps alone, of any -district of street lamps only, can never be undertaken with economy in -this capital, nor indeed in any other; for the money sunk in furnishing -the mains or pipes only, must always greatly exceed what any revenue -from the lighting of the streets alone can compensate. - -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 profit of -this mode of illumination is the least. Hence, the lighting of the -parish, or street-lamps alone, without lighting shops or houses, can -never be done with economy. - -It may be objected to the universality of our conclusion that the price -of coal differing very much in different places will occasion a -variation in the expence of the new mode of lighting. - -The price of coals can however have but little effect upon the cost of -the gas-lights; because the very refuse, or small coal, 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. This circumstance may contribute to -enable coal-merchants 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, which is a practice commonly followed. - -The demand which the gas-light occasions for inferior sorts of coal may -hereafter contribute to lower the price of the superior kinds, and keep -a level which cannot be shaken under any circumstances. It may -contribute to prevent combinations which do certainly operate to the -prejudice of the public, and sometimes put this great town at the mercy -of a few proprietors in the north, who deal out this commodity in any -way they please. The competition thus produced, it is impossible not to -consider as an advantage, which would tend to prevent such combinations, -and put the inhabitants of London out of the reach of them. - -The advantages which the coal trade must reap from the introduction of -the gas-light must be very considerable. There is already less waste, -but a greater consumption of coal than formerly. The lower classes of -the community are scantily supplied with firing; and nothing but a -reduction of price is necessary to increase to a very large amount the -average quantity of fuel consumed in the country. The lightness of the -coke produced by the gas-light manufacture diminishing the expence of -land carriage, facilitates its general diffusion--the comforts of the -poor are becoming materially augmented, and a number of useful -operations in agriculture and the arts are beginning to be carried on, -which have been hitherto checked by the extravagant price of fuel. If -any additional vent were wanted for the coke, it would readily be found -in the continental market; coke being better suited than coal to the -habits of most European nations. - -Many, and unquestionable as are the advantages of this new mode of -procuring and distributing light, it was not to be expected that an -invention which went to impair a branch of trade, in which a large -portion of skill and capital had hitherto been successfully employed -should escape encountering very considerable opposition. On the first -introduction of the gas-lights, great but happily unsuccessful -endeavours were made to alarm the public mind by dismal forebodings of -the destruction which would ensue to the Greenland trade, and the -consequent loss of a valuable nursery of British Seamen. When -impartially considered it will be found that there was nothing more in -this objection 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. - -Such clamour scarcely ever fails to be made when the extension of -machinery, the application of inanimate power, and the abridgment of -labour consequent on either, is a matter proposed. We are then sure to -be told that the scheme of mechanical or chemical improvement is pointed -against the human species, that it tends to drive them out of the system -of beneficial employment and that, on the whole, the sum of the -improvement is not only a less proportion of good to society, but a -positive accession of misery to the unemployed poor. - -The misfortune of this argument is that to be good for any thing, it -would prove a great deal too much. It is not confined in its scope to -any particular species or defined extent of improvement, but is equally -proscriptive of all improvements whatever. It is a principle for savage -life, not for a state of civilization. It takes for its basis that it is -an advantage to perpetuate that necessity for hard and incessant labour -under which man finds himself originally placed by nature, with all the -wants, privations, ignorance and ferocity, which are attendant on that -condition, and that every discovery, invention, or improvement which -tends to abridge the quantity required of human labour, and to augment -the resources for living and enjoyment is a serious injury to society. -The advocates of this narrow theory do not go the whole length of -maintaining that diminishing labour, and increase of substance, are in -themselves positive evils, a position too absurd perhaps for any one to -uphold; but they maintain what ends in a consequence nearly as untrue, -namely, that neither the one nor the other is of any advantage to -society at large. The palpable error of this theory is, that it supposes -that all improvements which tend to supersede human labour, are -necessarily made for the benefit of a few, and not for the common -benefit of the many; that instead of lessening to each individual the -share of labour requisite to obtain the means of his subsistence, their -only tendency is to lessen the value of each personas labour, and to -oblige him to work more in order to live equally well. - -Now, however the existing state of things may be in this country, or in -other countries, arising out of a variety of arbitrary circumstances, -foreign to the natural, and in all cases the ultimately inevitable -course of industry, it is a matter of justice, clear and undeniable, -that every improvement in society ought to be the property of the many, -and not of a few; and that it ought either to lessen the quantity of -labour necessary for acquiring the means of living, or to increase the -profit to be gained by continuing the same quantity of labour. Nor does -there seem any reason for believing that, in point of fact, the actual -distribution of things is so far from according with this principle of -justice as some superficial and prejudiced observers are fond of -representing. The labourer, or artizan, may now work a greater number of -hours daily than he did years ago; but how seldom do we find this to be -the case without his comforts being more than proportionally multiplied, -and his ultimate independence from labour essentially promoted. In -general, however, the fact is, if we may give credit to well informed -economists, that the working classes do not labour more than formerly, -and yet live, or at least have the means of living better; and that by -working even less than formerly, they can obtain the means of living -quite as well. - -Let the real state of matters in this respect, however, be as it may, -the question comes to be one merely as to the distribution of the -produce of nature and of art, and instead of opposing improvements -because they tend to encrease that produce, the object of those who have -really the good of their fellow-creatures at heart, ought to be, to -encourage such improvements as much as possible, but at the same time to -obtain a correction of any partiality or injustice which may have crept -into the distribution of their beneficial consequences. It is not to be -denied that all new improvements which interfere with and change the -occupations and habits of the working classes of people, must at first -expose them to inconvenience and distress, against which it is in -fairness the duty of society to protect them; but let not that temporary -inconvenience and distress which can and ought to be provided against, -be held as an insuperable obstacle to the adoption of an improvement the -ultimate tendency of which it is to better the condition of mankind. - -It is likewise true that the manufacturing classes often suffer great -want by the occasional suspension of employment, and sometimes actual -oppression, by the demand for labour; but that involves a question more -immediately connected with political economy than the present subject. - -It is not the machinery that is in fault in such cases, but those -speculators who occasion an inordinate excess of employment, or those -statesmen who, with their folly, derange the great machine of human -interests and intercourse. - -Every invention which tends to diminish the labour of men must be a -benefit to the species; and it is wicked to argue against the use of any -thing from its occasional abuse. - -If the application of mechanical inventions thus tends to improve the -humanity of the public, if it reduces the necessity of hard labour, and -diminishes the danger of many occupations which we contend it does, they -who contribute to this object deserve our respect and gratitude. - -It may be true that we have now no such minds as those of Homer, or -Bacon, or others of their stamp; but we should reflect that the -circumstances which produced such characters are gone by, and great -faculties have found other objects and other materials to work with. - -The use of mechanical industry not only improves and augments the -comforts of domestic life, but it also, perhaps, does as much to soften -the feelings of mankind towards one another as the precepts of -philosophy. It tends to engender a detestation of hard labour, and to -make the world consider not what the labourer may be able to do in -tasking him, but what he ought to do without detriment to himself. It -effects this by withdrawing, to a great degree, from observation, the -distressing spectacle of men and animals toiling beyond their strength. - -It ought never to be forgotten, that it is to manufactories carried on -by machinery, and abridgment of labour, that this country is indebted -for her riches, independence, and prominent station among the nations of -the world. - -Authentic estimates have shewn, that the use of machinery in Great -Britain, is equivalent to an addition to the population of upwards of -_one hundred millions of adult persons_. - -This immense accession of power, has enabled this country to withstand -assaults, and to achieve objects of political ambition, that appear -almost miraculous when compared with the geographical extent and -numerical population of the kingdom. - -With respect to what has been advanced as to the probable injury that -would result from the general adoption of the gas-lights all over the -country, to the Greenland trade, it may be observed that the 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 of able bodied sailors; and being protected men, not subject to -the impress law, they are rendered useless for national defence. The -nursery of British seamen is the coasting trade; and as the gas-light -illumination becomes extended it will increase that trade as much as it -diminishes 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. The consequence of lighting our dwellings -and manufactories with gas can in fact prove injurious only to our -continental friends, one of whose staple commodities, tallow, we shall -then have less occasion to purchase, although the new lights can never -supersede entirely the use of candles and moveable lights. - - - - -PART II. - - -_Outline of the new art of procuring light by means of coal gas, and -Theory of the production of Gas Lights._ - -All substances, whether animal, vegetable, or mineral, consisting of -carbon, hydrogen, and oxigen, when exposed to a red heat, produce -various inflammable elastic fluids, capable of furnishing artificial -light. - -The gases thus obtained are called carburetted hydrogen; they produce, -from their combustion, water and carbonic acid. The species of -carburetted hydrogen, procured from pit-coal, has of late been called -_coal gas_. - -We perceive the evolution of this elastic fluid, during the combustion -of coal, in a common fire. The coal, when heated to a certain degree, -swells and kindles, and frequently emits remarkably bright streams of -flame. And after a certain period these appearances cease, and the coal -glows with a red light. - -The flame produced from coal, wood, turf, oil, wax, tallow, or other -bodies, which are composed of carbon, hydrogen and oxigen, proceeds from -the production of carburetted hydrogen gas, evolved from the combustible -body when in an ignited state. - -It must have been noticed at the same time, that in the common mode of -burning coal in a fire-place, or stove, nearly the whole of this -inflammable gaseous matter is lost. 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 part of the -coal, they will catch fire and burn with a bright flame. The fact is, -that the greater part of the carburetted hydrogen gas, capable of -affording light and heat, continually escapes up the chimney, during the -decomposition of the coal, whilst only a small part is occasionally -ignited, and exhibits the phenomena of the flame. - -If coal instead of being burnt in the way now stated, is submitted at a -temperature of ignition in close vessels, all its immediate constituent -parts may be collected. The bituminous part is melted out in the form of -coal 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 hydrogen, carbonic -oxide, carbonic acid, and sulphuretted hydrogen also makes their -appearance, and the fixed base of the coal, alone remains behind in the -distillatory apparatus, in the form of a carbonaceous substance called -_coke_. An analysis of the coal is thus effected by the process of -destructive distillation. The products which the coal furnishes may be -separately collected in different vessels. The carburetted hydrogen, or -coal gas, when freed from the foreign gases may be propelled in streams -out of small apertures, which when lighted may serve as a flame of a -candle and then form what we now call GAS LIGHTS. - -It is in this manner that from pitcoal a production of our own soil, we -procure a pure, lasting and brilliant light, which in other cases must -be derived from materials in part imported from abroad. - -In order to apply this mode of procuring light on a large scale as now -practised with unparalleled success in this country, the coal is put -into vessels called retorts and furnished with pipes connected with -reservoirs to receive the distillatory products. The retorts are fixed -into a furnace, and heated to redness. The heat developes from the coal -the gaseous and liquid products, the latter are deposited into -receivers, and the former are conducted through water in which quick -lime is diffused by which the carburetted hydrogen gas is purified. The -sulphuretted hydrogen and carbonic acid which were mixed with it, become -absorbed by the quick-lime, and the pure carburetted hydrogen is stored -up in a vessel called the gas-holder, and is then ready for use. - -From the reservoir in which the gas has been collected, proceed pipes, -which branch out into smaller ramifications until they terminate at the -place where the lights are wanted and the extremities of the branch -pipes are furnished with stop-cocks to regulate the flow of the gas into -the burners or lamps. - -The production of gas-lights, is therefore analogous to that of flame -produced from tallow, wax, or oil. All these substances possess, in -common with coal, the elements of certain peculiar matters, which are -capable of being converted into inflammable elastic fluids by the -application of heat. - -The capillary tubes, formed by the wick of a candle, or lamp, serve the -office of the retorts, placed in the heated furnace in the gas-light -process and in which the inflammable gaseous fluid is developed. The wax -tallow or oil, is drawn up into these ignited tubes, and is decomposed -into carburetted hydrogen gas, and from the combustion of this substance -the illumination proceeds. In the lamp as well as in the candle, the -oil, or tallow, must therefore be decomposed before they can produce a -light, but for this purpose the decomposition of a minute quantity of -the materials successively, is sufficient to give a good light. Thus -originates the flame of a candle or lamp. - -Nothing more therefore is aimed at in the gas-light process, than to -separate the immediate products which coal affords, when submitted to a -temperature of ignition in a close vessel; to collect these products in -separate reservoirs, and to convey one of the products, the inflammable -gas, by means of pipes and branching tubes, to any required distance, in -order to exhibit it there at the orifice of the conducting tube, so that -it may be used as a candle or lamp. - -The whole difference between the gigantic process of the gas light -operation, and the miniature operation of a candle or lamp, consists in -having the distillatory apparatus at the gas-light manufactory, instead -of being in the wick of a candle or lamp. In having the crude -inflammable matter decomposed previous to the elastic fluid being -wanted, and stored up for use, instead of being prepared and consumed as -fast as it proceeds from the decomposed oil, wax or tallow; and lastly, -in transmitting the gas to any required distance, and igniting it at -the burner or lamp of the conducting tube, instead of burning it at the -apex of the wick. The principle of the gas-light manufacture is -therefore rational, and justifiable by the general mode in which all -light is produced. - -It only remains to be observed that while the new and important use to -which pitcoal may thus be applied, affords a strong confirmation of what -has been well observed, that of all subterraneous combustible -substances, coal is in this country by far the most important natural -production.[2] “It is connected not only with the necessities, comforts -and enjoyments of life, but also with the extension of our most -important arts, our manufactures, commerce and national riches. - - [2] Davy on the Safety Lamp. - -“Essential in affording warmth and preparing food, it yields a sort of -artificial sunshine and in some measure compensates for the -disadvantages of our climate. - -“By means of it metallurgical processes are carried on, and the most -important materials of civilized life furnished, the agriculturist is -supplied with a useful manure and the architect with a necessary -cement. Not only manufactories and private houses, but even whole -streets and towns are lighted by its application, and in furnishing the -elements of activity in the steam-engine, it has given a wonderful -impulse to mechanical and chemical ingenuity, diminished to a great -extent human labour, and increased in a high degree the strength and -wealth of the country.” - - - - -PART III. - - -_Classification of Pit-coal, and maximum quantity of gas, obtainable -from different kinds of Coal._ - -We have stated already that pitcoal is in this country the cheapest -crude natural production from which carburetted hydrogen gas can be -obtained in the large way. It is that which yields it in abundance, and -which can with the least trouble and expence be subjected to the -operation it has to undergo for the production of the gas.[3] Nature has -dealt this mineral out to us, with an unsparing hand, and has provided -mines of coal which seem to defy the power of man to exhaust. - - [3] Other Substances from which carburetted hydrogen gas, may be - economically obtained, are animal and vegetable oil, tar, both - vegetable and coal tar; pitch, resin, the essential oils obtainable - from vegetable and from coal tar, and the compact species of turf. On - this subject we shall speak hereafter. - -The principal coal mines in England are those near Newcastle and -Whitehaven. The town of Newcastle stands on beds of coal which extend to -a considerable distance round the place, and which as far as concerns -many hundred generations after us, may be pronounced inexhaustible. - -Pitcoal like all other bituminous substances is composed of a fixed -carbonaceous base in the state of bitumen, united to a small portion of -earthy and saline matter, which constitute the ashes left behind when -the coal is burnt. The proportions of these parts differ considerably in -different kinds of coal; and according to the prevalence of one or other -of them, so the coal is more or less combustible, passing by various -shades from the most inflammable coal into blind coal, Kilkenny coal, 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. - -All the varieties of coal used in this country for fuel may be divided -into the following classes. - -The first class comprehends those varieties which are chiefly composed -of bitumen only, which take fire easily, and burn briskly with a strong -and yellowish white blaze, which do not swell or cake on the fire, and -require no stirring, which produce no slag, and by a single combustion -are reduced to light white ashes. Some of this species of coal when -suddenly heated crackle and split into pieces, especially if laid on the -fire in the direction of the cross fracture of their laminæ. - -Cannel coal, deserves to be placed at the head of this class; next to -this, we may rank all those descriptions of coal known in the London -market by the names of Hartley, Cowper’s Main, Tanfield Moor, Eighton -Main, Blythe, and Pont Tops. It also includes the sort of coals found in -several parts of Scotland, called Splent coal, and some of those raised -on the Western Coast of England. - -Most of the coals raised in Staffordshire ought likewise to be classed -among this species of coal, but the line of distinction between these, -and the classes subsequently named, cannot be accurately drawn. - -The following table exhibits the maximum quantity of gas obtainable from -the first class of coal.[4] - - [4] Own Experiments, made at the Royal Mint Gas-Works. - - One Chaldron of Coal, produces Cubic feet of Gas. - - Scotch Cannel coal 19,890 - Lancashire Wiggan coal 19,608 - Yorkshire Cannel coal, - (Wakefield) 18,860 - Staffordshire coal,[5] - First variety,[6] 9,748 - Second variety, 10,223 - Third variety, 10,866 - Fourth variety, 9,796 - Gloucestershire coal,[7] - First variety, (Forest of Dean, High Delph) 16,584 - Second variety, (Low Delph) 12,852 - Third variety, (Middle Delph) 12,096 - Newcastle coal, - First variety, (Hartley) 16,120 - Second variety, (Cowper’s High Main) 15,876 - Third variety, (Tanfield Moor) 16,920 - Fourth variety, (Pontops) 15,112 - - [5] They require a much higher temperature, than is necessary for the - decomposition of Newcastle coal. - - [6] For the maximum quantity of gas produced from this and the three - succeeding varieties of coal, I am indebted to J. Gostling, Esq. - Proprietor of the Birmingham Gas Works. - - [7] Most varieties afford a porous, and very friable coke. - -The second class of coal, comprehends all those varieties which contain -a less quantity of bitumen, and a larger quantity of carbon than the -first class. They burn with a flame less bright and of a more yellowish -colour, and the last portion of flame they are capable of yielding is -always of a lambent blue colour, they become soft after having laid on -the fire for some time, swell in bubbles and pass into a state of -semi-fusion, they then cohere and coke, puff up and throw out tubercular -scoriæ, with a hissing noise, accompanied with small jets of flame. - -In consequence of the agglutination and tumefaction, the passage of air, -if this sort of coal be burnt in an open grate, is interrupted, the fire -burns as it is called hollow, and would become extinguished if the top -of the coal were not from time to time broken into with the poker. - -The coke formed from this species of coal is more compact than that -produced from the first sort of coal, and is well calculated for -standing the blast of bellows in metallurgical operations. In respect to -weight the second class of coal is considerably heavier than those of -the first class, the difference amounts to not less than from -twenty-eight pounds to thirty-three pounds in the sack of coal. A -chaldron of some varieties of this class of coal, if the coals are in -large lumps, weighs upwards of twenty-eight hundred weight. - -The usual denomination by which the second class of coal is known in the -London market, is that of _strong burning coal_. The following varieties -are sufficiently known, Russel’s Walls-End; Bewick’s and Craister’s -Walls-End; Brown Walls-End, Wellington Main, Temple Main, Heaton Main, -Killingsworth Main, Percy Main, Benton Main, and some varieties of the -Swansea coal. - -The smaller kinds of coal of this class are preferred by smiths, because -they stand the blast well. They make a caking fire so as to form a kind -of hollow, space or oven, as the workmen call it. Some varieties abound -in pyrites, and others are intersected with thin layers of slate and -lime-stone. They require more heat for being carbonized than the first -class, and the fluid obtained from it by distillation, contains a -considerable portion of carbonate, sulphate, and hydrosulphuret of -ammonia. They are well calculated for the production of coal gas; the -coke which they produce is not very brittle, and will bear moving from -place to place, without crumbling into dust. - -The following table exhibits the maximum quantity of gas obtainable from -the second class of coal.[8] - - [8] Own Experiments, made at the Royal Mint Gas-Works. - - One Chaldron of Coal, produces Cubic feet of Gas. - - Newcastle coal, - First variety, (Russel’s Wall’s End) 16,876 - Second variety, (Bewick and Craister’s Wall’s End) 16,897 - Third variety, (Heaton Main) 15,876 - Fourth variety, (Killingsworth Main) 15,312 - Fifth variety, (Benton Main) 14,812 - Sixth variety, (Brown’s Wall’s End) 13,600 - Seventh variety, (Mannor Main) 12,548 - Eighth variety, (Bleyth) 12,096 - Ninth variety, (Burdon Main) 13,608 - Tenth variety, (Wears Wall’s End) 14,112 - Eleventh variety, (Eden Main) 9,600 - Twelfth variety, (Primrose Main) 8,348 - -The third and last class of coals includes those which are destitute of -bitumen, being chiefly composed of carbon in a peculiar state of -aggregation, evidently combined chemically with much earthy matter. -Coals of this class require a still higher temperature to become ignited -than any of the former classes, they emit little or no smoke. When laid -on a fire they burn away with a feeble lambent flame, indeed some -varieties give no flame at all, but burn merely with a red glow, -somewhat like charcoal, and at length become consumed without caking. -They leave a small portion of heavy ashes. - -When submitted to distillation they afford little or no tar; of a -consistence almost resembling pitch, and a gaseous fluid chiefly -composed of gaseous oxide carbon and hydrogen gas. It is scarcely -necessary to add that they are altogether unfit to be employed for the -manufacture of coal gas. The Kilkenny, Welch, and stone or hard coal -belong to this class. They require a strong draught when burnt in an -open fire-grate, and the large quantity of gaseous oxide of carbon which -they furnish during their combustion is extremely offensive. This is -particularly the case with Kilkenny coal. The Welch stone or hard coal -is better adapted for culinary purposes, and there is reason to believe -that this species of coal might be rendered useful in the smelting of -iron ore, by a slight modification in the metallurgic process employed -for extracting the metal from its ore, but to eradicate prejudice, and -to alter established practices is a work which nothing but time can -effect. This species of coal is sent all over the kingdom; it is well -calculated for the operations of drying malt and hops, and its small -coal or culm has been found a more economical fuel, than Newcastle and -Sunderland coals, for the burning of lime and bricks, and for all other -processes where no blazing fuel is required. - -The following table exhibits the maximum quantity of gas obtainable from -this class of coals. - - One Chaldron of Coal, produces Cubic feet of Gas. - - Welch coal. First variety, from - Tramsaren, near Kidwelly,[9] 2,116 - Second variety, from the yard vein at the same place 1,656 - Third variety, from Blenew, near Llandillo 1,416 - Fourth variety, from Rhos, near Ponty Barren 1,272 - Fifth variety, from the Vale of Gwendrath 1,292 - Sixth variety, from ditto 1,486 - - [9] The coal for these Experiments was supplied gratuitously, to the - Gas Works of the Royal Mint, by Sir W. Paxton of Middleton Hall. - -When we consider the before mentioned varieties of coal in an economical -point of view, as fuel to be used in the gas-light process, for heating -the retorts, it appears from a series of experiments that have been made -under my direction, that the second class of coal comprehending those -varieties which contain a larger quantity of carbon than bitumen (p. -45,) afford the most economical fuel, they act less on the grate bars, -and fire bricks of the furnace than those varieties which take fire -easily and burn briskly with a strong blaze. A mixture of Welch Stone -coal, and Newcastle coal forms an excellent economical fuel, where an -intense glowing fire is required. - - - - -PART IV. - - -_Form and dimensions of the Retorts originally employed for -manufacturing Coal Gas._ - -The proper mode of constructing the retorts in which the coal is -distilled, and the art of applying them form an object of primary -importance in every gas-light establishment. According as the -manufacture is conducted in these respects with a due regard to physical -principles, depends the quantity of gas which can be obtained in any -given time, from any given quantity of coal, the consumption of fuel -requisite for the production of that quantity of gas, the degree of -deterioration to which the distillatory vessel is subjected, the quality -in some measure, of the gas itself; and, as the ultimate result of all -these circumstances, the cheapness at which the gas light can be -furnished to the consumer. - -The essential influence of these various particulars on the value of the -art of lighting with coal gas, has led to much assiduous enquiry to -ascertain that sort of construction and mode of operation in respect to -each of them which may be most advantageous. And in no branch of the new -art of procuring light, has a greater variety of plans of improvement -been submitted to the several directing boards of gas works, or more -labour and expence been incurred in experiments conducted on a large -scale, to ascertain the relative merits of these plans. Nor is there any -part of the gas-light process in which a greater number of material -alterations have been put in practice. - -In the earlier periods of lighting with coal gas the retorts employed at -some of the gas-light establishments in the metropolis, were hollow -cast-iron cones from six to seven feet in length. The greatest diameter -of the cone which formed the mouth of the retort, measured from twelve -to fifteen inches, and its smallest diameter at the vertex from nine to -ten inches. - -At other gas works the form of the retort was a parallelopiped from six -to seven feet long, the horizontal, and vertical sides were -respectively to each other, as 20 to 15 inches. The angles of these -retorts were slightly rounded. Fig. 16, plate V. exhibits a vertical -section of this retort. - -Again at other establishments semi-cylindrical retorts, placed -horizontally upon their flat surfaces were employed; fig. 18. pl. V. The -length of these retorts was from five to six feet, and their vertical -and horizontal diameters were to each other as 6 inches, to 18 inches. -And at a few establishments, ellipsoidal retorts, fig. 17, plate V. were -used; these measured from five feet and a half, to six feet in length, -their major and minor axes bore different proportions to each other at -different establishments. At the first adoption of these retorts, the -proportions varied but little from the cylinder, but subsequently the -difference between the major and minor axes became gradually increased -till at last the major axis has become to the minor axis, as 20 to 10 -inches, and at some gas works the proportions are as 25 to 10 inches. - -With vessels of these forms the distillatory process was carried on for -some years, and the quantity of fuel employed to decompose a given -quantity of coal by means of them, amounted to from thirty to -thirty-six per cent. - -When the dimensions of the retorts were increased, both the quantity of -fuel and time required for the decomposition of a given quantity of coal -was in a far greater ratio; and the operations of charging and -discharging the retorts, very troublesome. - -Retorts of smaller dimensions have likewise been tried, but the more -frequent charging and discharging, which they require, occasioned such a -waste of time and labour, and such intermissions, in the temperature -necessary for the process of distillation, (besides being attended with -other disadvantages which will be afterwards explained), that they were -speedily discontinued at the gas works where they had been adopted. - -The use of conical retorts, as well as of those of a semi-cylindrical -and parallelopipedal form, has of late been discontinued in most -establishments. The conical shape not only diminishes the capacity of -the vessel, but also renders it incapable of being heated economically. - -From two comparative series of operations made on a large scale, and -continued for upwards of six months with conical and cylindrical -retorts, with a view to determine the comparative power of these -vessels, it has been proved that the same quantity of gas which can be -obtained by means of forty conical retorts, may be procured in the same -time and with the same quantity of coal and fuel, by means of -thirty-four cylindrical retorts.[10] - - [10] These Experiments were made at the commencement of the new art of - lighting with gas, at the Westminster Chartered Gas Works, by Messrs. - Grant and Hargraves. - -Similar experiments have been undertaken, to determine the comparative -action of semi-cylindrical and parallelopipedal retorts.[11] The latter, -when kept in action day and night, do not long retain their shape; their -sides collapse, their capacity becomes diminished, their angular form -causes the heat to act upon them unequally, in whatever manner it may be -applied, in consequence of which they suffer more deterioration in some -parts than in others. Besides, they require a much larger proportion of -fuel for decomposing a certain quantity of coal than the cylindrical -retorts. - - [11] At the Birmingham Gas Works. - -Semi-cylindrical retorts, with the base of the retort bent inwards, so -as to give the vessel a kidney-shaped form, have likewise been tried. -But this shape is still less advantageous; they could not be made to -work uniform, they required more heat, and their deterioration was more -rapid than cylindrical retorts. They could not be kept fit for use when -worked day and night, more than about five months. And with regard to -ellipsoidal retorts, it must be confessed, that the experiments that -have as yet been made upon a large scale to ascertain their powers, are -not of a nature to enable us to decide on their merits. No experiments -have been carried on with retorts of this description in the metropolis -for a sufficient length of time, with that care and attention which the -subject demands, to ascertain their comparative power. From what however -has been done, there is reason to believe that ellipsoidal retorts, -might be found more advantageous, than those of a cylindrical form now -in use. An ellipsoidal retort, 20 inches by 10 in diameter, and six feet -long, weighs 14 Cwt. - -The reader will thus observe, that of all the forms of retorts which -have been hitherto fairly tried, upon a large scale, it has been -satisfactorily ascertained, (excepting only as to the ellipsoidal -retorts), that the cylinder is the best form for decomposing coal in -masses, from five to eight or ten inches in thickness. - -It is perhaps needless to state that in making experiments on the -comparative value of the best form of cast-iron retorts, it is obvious -that the operations should be continued for some months uninterruptedly; -no conclusion can be drawn that may become practically useful in the -large way, from processes carried on for a few weeks only. It is -absolutely essential that the comparative trials be continued for months -together, and that the inferences be taken from the total quantity of -coal used during that period, compared with the total quantity of gas -obtained, the deterioration of the retorts, and the time and labour -expended. - -Proceeding on erroneous data, many have persuaded themselves of having -noticed that parallelopipedal and semi-cylindrical retorts last longer -fit for use than those of a cylindrical shape, an assertion of which -subsequent trials, conducted in the manner just stated, has clearly -shown the fallacy. Enough has been done at the different gas works in -the capital to settle this point, and there is now but one opinion -amongst those who are best qualified to judge of the subject. Every body -who has made the trial on a large scale, is convinced as already stated, -that the best form of the retort for manufacturing coal gas where the -process is conducted on the plan of decomposing coal in masses or layers -of from four to eight inches in thickness, is a cylinder six and a half -feet long, and one foot in diameter, and accordingly retorts of this -shape and dimensions are now used in all the best regulated gas -establishments in the metropolis. - -A cylindrical retort of the description before named, weighs about nine -and a half to ten hundred weight. These and all other shaped retorts are -furnished with a moveable lid or cover having a conical edge to fit the -mouth-piece; the cover is rendered air-tight, not as formerly by -grinding, a mode which was costly, but by the interposition of a thin -coat of loom, between the lid and the mouth of the retort. - -The mouth-piece forms a separate part of the retort. It is bolted and -screwed to a flanch which terminates the mouth of the retort, so that -when the retort is worn out, the mouth-piece may be detached and applied -to new retorts. - -There are now in action 620 cylindrical retorts, at the two chartered -Gas Works[12] in the metropolis; and the total number of retorts at all -the London gas establishments amounts to 960. - - [12] - - { Westminster Station 250 Retorts. - Westminster Gas Works, { Brick Lane ditto 190 ditto - { Norton Falgate ditto 50 ditto - City of London Gas Works, Dorset Street, 130 ditto - --- - 620 - - -_Application of heat.--Flue Plan originally adopted._ - -It must be obvious that the durability of the distillatory apparatus, -greatly depends on the manner in which the heat is applied, to effect -the decomposition of the coal contained within the retort. If the heat -be very intense the whole vessel is rapidly destroyed. If it be too -languid, the distillatory process is protracted, and much fuel, time, -and labour wasted to no purpose; and the retort is speedily -deteriorated, if the heat acts upon one part of it more than upon -another. - -The different kind of retorts of which a description has been given in -the preceding pages, were originally heated by means of flues passing -under and over them. The retorts were placed horizontally and fixed in -brick-work. One fire-place at the extremity of the mouth of the retort -where the coals are introduced, and whence the coke is withdrawn, was -allotted to every two retorts in the series. - -At the commencement of the new art of procuring light the quantity of -fuel as before stated, necessary to decompose a given quantity of coal, -amounted to from thirty to thirty-six per cent of the coal decomposed; -that is to say, it required from thirty to thirty-six parts of fuel to -decompose one hundred parts of coal. This quantity has been much -lessened by a better mode of setting the retorts, and it is now the -general opinion that the operation of decomposing coal, by means of -cylindrical, parallelopipedal, or semi-cylindrical retorts, must be -considered as well conducted when one hundred parts of coal are -decomposed by twenty or twenty-five parts of fuel. This appears to be -the minimum quantity of fuel, that can be employed for the complete -decomposition of coal by means of these retorts, and with the least -deterioration of the distillatory vessel. - -The following statement will exhibit what has been done in this branch -of art. - - -_Report on a course of Operations, made with sets of 66, of 30, of 116, -and of 64 retorts, worked on the Flue Plan._ - -In order to determine the relative value of the best method of setting -cast-iron retorts, it was deemed necessary to ascertain whether three -retorts might not be heated, instead of two, as before stated, by one -fire-place and branching flues. To determine this the following -processes were carried into effect. - - -_Process I._ - -Sixty-six cast-iron cylindrical retorts, of the usual size, namely, six -and a half feet long, (exclusive of the mouth-piece) and one foot in -diameter, internal dimensions, where set on the plan of three retorts to -one fire-place, at the Westminster gas-work station, and a series of 30 -similar retorts were erected at another station belonging to the same -company, at the East end of London. - -The experiments were pursued with every degree of justice in the detail, -the retorts were kept in action day and night for upwards of four -months, and the results noted down with exactness. The final reports -from the two establishments were found to concur in showing that nothing -was to be gained by this method over that previously in use. - -The time occupied for the distillatory process was not abridged. The -consumption of fuel was greater--no larger quantity of gas was obtained -from the quantity of coal carbonized. The produce with regard to coke -was in the usual ratio, and the retorts were destroyed in about one -third less time than when only two were heated by one fire-place. - - -_Process II._ - -The apparently conclusive results of these experiments did not, however, -prevent another set of experiments from being made on the same -principle, extended even a degree farther. The problem now proposed to -be solved, was, whether four retorts might not be heated with economy, -in a manner which had been found already wasteful with respect to three, -that is, whether four instead of two retorts might not be heated -economically by means of one fire-place. - -On this plan one hundred and sixteen cylindrical retorts of the usual -dimensions were again erected at the Westminster gas establishment, and -sixty-four at another station belonging to the same chartered company. -These retorts were kept in action in the best possible manner night and -day, and the results, as might have been anticipated, only served to -confirm the facts already established by experiment with three retorts. - -Nothing was found to be gained; and so far from their being any saving -in respect of fuel and wear and tear of the retorts, the waste beyond -that which takes place on the plan of two retorts to one fire-place, -was increased to nearly twenty-five per cent., accompanied by a -corresponding acceleration of injury to the retorts. - -It was still imagined, however, that the great waste of fuel and the -ultimate unfavourable result of these proceedings, which were repeated -with as little success at several other gas-works in the metropolis with -parallelopipedal retorts, and at other works with retorts of a -semi-cylindrical form, set in a way different from that pursued at the -Westminster station, might probably have been owing to the unavoidable -circumstance, that the heat was not made to act upon all the retorts -employed uniformly in each series of four retorts, but in a manner so -variable that one, or even two of the series would become destroyed and -rendered useless, while the others continued uninjured in a sound and -working state. - -The excessive waste of fuel was occasioned, we are told, by the number -of injured retorts, which became useless, and were nevertheless required -to be kept red hot to no purpose; for it was actually found that when -one retort of a series of four became injured, the same fire which had -heated the whole four, still required to be kept up to maintain in -action the remaining three of the series, and so on with respect to the -whole range, till ultimately when there might remain only eighty retorts -actually in use, as many fire-places were required to be in full action -as would have been sufficient to serve for one hundred retorts. - -Attempts accordingly were now made to get over this supposed cause of -the losing results, already obtained from the plan of four retorts to -one fire-place, by a new series of similar operations, in which the -retorts were fixed in such a manner, that those which happened to become -injured during the process, might easily and immediately be withdrawn -without materially disturbing the rest, and replaced by new ones. The -waste of fuel was, it is clear, greatly lessened by the expedient; yet -still upon the whole there was no such variation from the general -results obtained by the preceding experiments, as to justify the -adoption of this plan of increasing the number of retorts worked by one -fire-place, on any principle of sound economy. - -The great obstacle, as the reader will at once perceive, to working more -than two retorts, no matter whether cylindrical, or of any of the other -forms before named, with economy, by means of one fire-place, evidently -arose from the difficulty of conducting the heat by means of flues -around the series of retorts, in such a manner that the heat shall act -with equal force on all the retorts. - -It is almost needless to state, that the construction of the -fire-places, and the direction of the flues for applying the heat to the -retorts, were varied by different workmen, who prided themselves on -being able to aid the object in view, but the result always showed even -that when the draft of the fire-place was well obtained, the action of -the heat upon the series of retorts could not be distributed equally and -kept up uniformly, except at a great expence of fuel and vast -deterioration of the distillatory vessels. The retorts always became -injured more in some parts than in others. The concentration and -rapidity of the draught of the fire, beyond a certain velocity was -always found highly injurious to the retort, and this observation has -been since amply confirmed. - -In a well constructed furnace, the deterioration of all the retorts in -the series is uniform over the whole vessel; no part of the retort is -_burnt out_, as the workmen call it, sooner than another part; and -whenever the contrary happens, we may pronounce the fire to be badly -applied. When there is such misapplication of the heat, the manufacturer -cannot depend upon the duration of the distillatory vessel; he is always -in a state of uncertainty with regard to their wear and tear, and it not -unfrequently has happened, under such circumstances, that a whole series -of retorts have become suddenly deteriorated. - - -_Oven plan lately adopted._ - -The results before detailed, with regard to the mode of setting -cylindrical retorts suggested the propriety of an entire change in the -mode of applying the heat, and this was at length fully carried into -effect by the adoption of ovens, or air furnaces, in which the retorts -are equally exposed to the action of heat on all sides. Mr. Rackhouse -has the merit of having first carried into effect this method, since -generally known by the name of the _oven plan_. - -The first experiments with these ovens were made on only one retort, -exposed in an oven to air intensely heated; but they were afterwards -repeated on two, three, four, and five retorts, successively. The -retorts suffered the action of heat thus applied, exceedingly well; -their deterioration was uniform, and the quantity of fuel required to -work them, was found always to be in a direct ratio to the number of -retorts employed. These experiments were carried on for upwards of nine -months, and it was found, that with five retorts in one oven, so that -the heated air could act upon all of them equally, without the flame -being directed forcibly upon them, this plan had a decided advantage, in -point of economy, over every other method previously adopted. Each oven, -containing five retorts, is heated by means of three fire-places, and -although it is true that the number of retorts is less by one, than what -could have been heated by three fire-places, on the original plan of two -retorts to one fire, yet still this method has been found to be far more -productive. The front wall of the oven may be readily taken down so that -a retort, when damaged, may be withdrawn, and replaced without -materially disturbing the rest. - -The oven plan of applying heat has been found equally advantageous for -parallelopipedal and semi-cylindrical retorts.[13] - - [13] The only gas-light establishment of great extent in the - metropolis, at which parallelopipedal retorts are still in use, is the - _South London Gas Works_. But it is solely owing to the very peculiar - care and economy with which all the details of this establishment are - conducted, under the immediate superintendence of a few active, - skilful and scientific proprietors, that they are able to compensate - for the loss, which in all ordinary cases is inseparable from the - employment of vessels of that description. - - -_Description of the Retort Oven._ - -Fig. 1, plate IV., represents a transverse section of one of the retort -ovens now in action at the Westminster Chartered Gas-Light Company’s -Works; similar ovens are likewise in use at the City of London Chartered -Gas-Light Works, and in many other provincial gas establishments. - -Fig. 2, plate IV., exhibits a longitudinal section, and fig. 1, plate V. -shows the front elevation of the oven, built about ten feet above the -ground, upon piers or arches, which saves brick-work and allows a stage -or platform to be erected in front of the fire-places of the ovens. See -fig. 2, plate IV. - -Between the back part of the ovens and the wall of the building in which -they are erected, is left an empty space of a few inches to prevent the -heat of the oven being communicated to the wall, as is seen at Y in fig. -2, plate IV. - -The whole interior of the oven, as well as the horizontal flue which -pass underneath the crown of it, near the upper tier of retorts, is -lined with fire bricks. The uppermost part or crown of the arch is -constructed of large fire bricks of such a shape as will allow to -flatten the upper part of the arch as much as possible, in order to -contract the space between the two upper retorts and the crown of the -arch of the oven. - -R. R. fig. 1, and 2, plate IV. and fig. 1, plate V. are cylindrical -retorts, placed horizontally in the oven, the lower series are either -supported by a large fire-brick, placed edgeways underneath the retort, -or by means of a stout wrought-iron pillar, as shown in the design. The -two upper retorts are supported by wrought iron straps, T, T, T, fig. -1, and T, fig. 2, plate IV. The straps pass through the brick-work of -the upper part of the oven, as shown in the designs, and they are -secured with screws and nuts to an iron bearing bar, the extremities of -which are supported by the outer walls of the oven. Each retort is -furnished at the extremity opposite to the mouth-piece, with a short -projecting piece or tail let into the brick-work of the oven, as seen in -the design, fig. 2, plate IV. - -M. Fig. 2, plate IV. shows the mouth-piece of the retort with its cross -bar and hand-screw; and fig. 6, plate V. shows the mouth-piece drawn to -a larger scale. E. is the hand-screw, with its cross or bearing bar D, -which passes through the projecting arms C. C. The lid of the -mouth-piece has a conical edge, so that it fits close when pushed into -its place by means of the hand-screw E. Fig. 7, plate V. is the lid -which closes the mouth-piece; the handscrew E, fig. 6, presses the lid -close, to render it air-tight, a thin stratum of loom luting being first -applied to the orifice of the mouth-piece. - -F. fig. 2, plate IV., is the fire-place, with the ash-pit E of the -oven. The door of the ash-pit is provided with three slits covered -within by a register slide, to regulate the admission of air as occasion -may require. - -The fire passes freely and uniformly round all the retorts, and the -whole cavity of the oven acquires an equable temperature, which it -retains, if the workman takes care to admit as little air as possible, -through the register door of the ash pit, when the upper part of the -arch, or crown of the oven has acquired a bright cherry red heat. - -We have stated already that in front of the oven, is a platform, as -represented in the sketch, fig. 2, plate IV. In the floor of this -platform, and directly underneath the mouth-piece of the retorts, all of -which project beyond the brick-work of the oven, is an opening covered -with an iron trap door; through this door the red hot coke, discharged -from the retorts, is suffered to fall below the stage or platform into a -cellar, or other fire-proof place, that it may not annoy the workmen. O, -O, fig. 1, plate V. denotes this opening through which the coke falls. - -P, fig. 2, plate IV., and P. P. fig. 1, plate V. is a pipe proceeding -perpendicularly from the upper part of the mouth-piece of each retort, -the other extremity of which descends into the horizontal hydraulic main -H, which is shown in fig. 2, plate IV. and plate V., supported upon iron -columns. This pipe serves to convey away the liquid and gaseous products -which become disengaged from the coal in the retort during the -distillatory process. - -The liquid substances, namely the tar and ammoniacal fluid, collect in -the hydraulic main H, plate IV. and V., which is furnished with a -perpendicular diaphragm or partition plate to cause a certain quantity -of the liquid deposited in it to accumulate to a certain height, and -thus to seal the perpendicular pipe P. The liquid cannot flow out of the -horizontal pipe H, till it rises to the level of the diaphragm. This -arrangement is distinctly shewn at H. fig. 2, plate IV., where the -diaphragm or partition plate is seen in the section of the hydraulic -main, together with the extremity of the perpendicular pipe P., -descending into the fluid contained in the hydraulic main. - -K, Fig. 1, plate V. is the discharging pipe, connected with the upper -part of the horizontal main H: it serves to convey away the gaseous and -liquid products from the hydraulic main H. By means of this pipe the tar -and ammoniacal fluids are conveyed into any convenient reservoir, called -the tar cistern, which is perfectly air-tight, and from this vessel the -liquid may be drawn of by means of a pipe or stop-cock. The extremity of -the pipe which communicates with the liquid, is bent downwards, so that -no air can enter the vessel: this arrangement is shown at fig. 3, plate -II. - -It is essential that the condensation of the vaporous fluids should be -fully completed before they reach the tar cistern. To effect this, there -is usually allowed a considerable distance to intervene between the -discharging pipe K, fig. 1, plate V., and the reservoir destined to -receive the condensible products; or the pipe is made to pass through a -vessel containing water, called the condenser, which acts in a similar -manner as the refrigeratory of a common still. It is obvious that it is -immaterial how the condensation of the vaporous fluid is effected; it is -essential, however, that the condensation should be complete before the -liquid tar and ammoniacal fluid reach the reservoir destined to receive -these products. - -The gaseous fluid which accompanies the condensible products, are then -made to pass into the lime machine, of which we shall speak hereafter, -in order to be deprived by means of quick-lime and water, from the -portion of sulphuretted hydrogen and carbonic acid gas which was -combined with the gas. And when this has been accomplished, the purified -gas is conveyed into the gas-holder, where it is stored up for use. This -part of the operation will be rendered more obvious hereafter. In some -establishments, the hydraulic main is furnished with two discharging -pipes, the one carries away the condensible fluid, into which the -perpendicular pipes P, fig. 2, plate IV. dip, whilst the other serves to -convey away the gaseous fluids to a condensor, in order to deposit the -vaporous portion of condensible liquid it may contain, and from thence -the gas passes into the purifying apparatus, or lime machine. X, fig. 2, -plate IV., is a small screw plug, which, when opened, restores the -equilibrium of the air within and without the retort previous to the lid -being taken off, to prevent the loud report, which otherwise happens -when the lid or cover of the retort is suddenly removed. To avoid these -explosive reports which had become a nuisance to the neighbourhood of -gas works, the practice of gradually withdrawing the lid of the retort, -and at the same time presenting a lighted torch has been adopted at some -works, which fully remedies the evil. - -The number of retort ovens at the Westminster Chartered Gas Works’ -Stations, amounts to four hundred and ninety. - - - - -PART V. - - -_Difference in the quantity of Gas evolved during different periods of -the distillatory process, and economical considerations resulting -therefrom in the manufacture of Coal Gas._ - -In conducting the decomposition of coal, the evolution of the gas is far -from being, with regard to quantity, uniform during different periods of -the distillatory process. The formation of the gas is more rapid in the -beginning of the process, and gradually slackens as the operation -proceeds. The gas also differs in its chemical constitution, at -different periods of the process; although in the case of large -supplies, this difference is of little consequence after the gas is -purified in the usual manner. The former consideration, however, has -given rise to various modes of operating, of which it will be proper to -take some notice. - -It must be obvious, that in proportion as the mass of coal in the retort -becomes carbonized or converted into coke, the exterior surface becomes -a gradually increasing obstacle to the action of the heat upon the -interior or central part of the coal remaining to be decomposed. The -heat required on that account must be more intense, and kept up to no -purpose, and the extrication of gas becomes slower and slower, as the -operation proceeds. - -The loss occasioned by this rapid diminution of the means employed, is -serious in every point of view, in regard as well to the quantity of -fuel used and time wasted, but it is unavoidable in the operation of -decomposing coal in masses or layers from 5 to 10 inches in thickness, -and must be a great drawback on the value of the gas-light discovery. - -The loss of fuel, it is obvious, must be just in proportion to the -quantity of carbonised matter, or coke, which is kept hot to no purpose, -awaiting the decomposition of that portion of coal, which it is the -very means of protecting from becoming decomposed. - -A striking exemplification of this statement will be seen in the -following table, exhibiting the result of the progressive produce of -coal gas, obtainable, in a given time, by means of cylindrical and -parallelopipedal retorts. - -_Experiment with one cylindrical Retort, containing two bushels of -coal._ - - Hours of the Quantity of Gas - distillatory process produced. - - First hour 115 cubic feet - Second ditto 81 ditto - Third ditto 78 ditto - Fourth ditto 70 ditto - Fifth ditto 66 ditto - Sixth ditto 55 ditto - Seventh ditto 49 ditto - Eighth ditto 42 ditto - --- - 555 cubic feet. - -The quantity of gas is at the rate of ten thousand cubic feet to the -chaldron (27 cwt.) of coal. - -_Experiment[14] with eighteen cylindrical Retorts, containing one -chaldron of coal._ - - Hours of the Quantity of gas - distillatory process produced. - - First hour 2000 cubic feet - Second hour 1488 - Third hour 1400 - Fourth hour 1301 - Fifth hour 1208 - Sixth hour 1000 - Seventh hour 897 - Eighth hour 691 - ---- - 9985 - -This experiment was made with retorts set on the flue plan. - -The coal employed was (Bewick and Craister’s Wall’s End), Newcastle -coal. - - [14] Communicated by Mr. T. S. Peckston, of the Westminster Gas Works. - -_Experiment with thirty-six parallelopipedal retorts, each containing -two bushels of coal._[15] - - Hours of the Quantity of Gas - Distillatory Process produced. - - In the first hour 4,058 - Second hour 3,028 - Third hour 2,871 - Fourth hour 2,526 - Fifth hour 2,380 - Sixth hour 1,971 - Seventh hour 1,754 - Eighth hour 1,450 - ------ - 20,038 - - [15] Own Experiments. - -The same heat as we have seen from the preceding table, p. 79, which is -necessary during the first hour of the operation, for the evolution of -one hundred and fifteen cubic feet of gas, is required in the eighth -hour for the production of no more than forty-two cubic feet, being a -decrease in effect of nearly two-thirds. - -When larger retorts are employed for decomposing coal in masses, from -five to ten inches in thickness, the loss of heat is in a much greater -ratio. - -In the hope of remedying in some measure the evils thus distinctly -ascertained to arise from the undue thickness of the masses of coal -subjected to the distillatory process, there have not been wanting -manufacturers who have had recourse to experiments on a large scale, to -ascertain with certainty whether they might not be gainers by suffering -the distillatory process, when the retorts are charged with two bushels -of coal, to proceed only for the space of six hours, instead of eight. -But the result of these experiments, as will be presently explained, has -shown satisfactorily that it is more profitable to keep up the -distillatory process for a period of eight hours, with the retorts fully -charged, than to abridge the operation by terminating it at the end of -six hours. - -Others again, have imagined, that it would be more economical to -decompose a less quantity of coal at once, or to decrease the thickness -of the stratum of coal in the cylindrical, or in any of the before named -retorts; but then again, serious difficulties occur in the practice. -The more frequent charging of the retorts and luting on the covers,[16] -which such a mode of operating require, occasions a prodigious waste of -fuel, time and labour. A greater number of retorts and more workmen must -likewise be employed, in order to produce the requisite quantity of gas -daily, which the manufacturer is called upon to supply; more space of -ground is required, and more dead capital must be sunk in the -establishment. The more frequent and sudden alterations of temperature -which the retorts necessarily suffer, by the more frequent introduction -of cold coal, renders them extremely liable to become injured; and it is -almost impossible to maintain a number of retorts thus worked, at an -uniform temperature. - - [16] When the cover is ground on, air-tight, the cost of the retort is - much increased. - -From various statements, which I have been favoured with, in -confirmation of my own observations on the best method of working -cylindrical retorts, it may suffice to lay before the reader the result -of a series of operations instituted by one of the largest and best -conducted establishments in this country; the public-spirited and -indefatigable directors of which have done more in the way of extensive, -costly, varied and long continued experiments, to improve the new art of -lighting with gas, than any other similar body in the kingdom; and -without whose exertions the gas light illumination would never have -reached the state of perfection it has attained. - - -_Report on a course of Experiments made to ascertain the comparative -Economy[17] of manufacturing every week, 857,667 cubic feet of gas, by -means of Cylindrical Retorts variously worked._ - - [17] The cost of materials and price of labour in this estimate, as - well as in all subsequent statements, is given such as they actually - were, at the time, when the experiments to which they refer were made. - - _Gas Light and Coke Company’s Works, - Westminster Station._ - - _February 8th, 1819._ - -_SIR_, - -_Enclosed are the result of a series of experiments made under my -direction with a view of ascertaining the relative value of the -different modes of working cast-iron cylindrical retorts, from which -you will perceive that it is more economical to work eight hours -charges, as the workmen call it, that is to say, to suffer the -distillatory process to go on for eight hours, when nearly two bushels -of coal are contained in each retort, than to discontinue the operation -at the end of six hours._ - - _I am with respect, - Sir, Yours, &c. - T. S. PECKSTON._ - - _To Mr. F. Accum, - Compton Street, Soho._ - - -_Process A._ - - =========+=======+================+================+========+========= - Number of|Number | | |Quantity|Quantity - Days the | of |Quantity of Coal| Quantity of | of | of Gas - Retorts |Retorts| decomposed for | Coal used | Gas |from one - were | in | obtaining Gas. | for Fuel. | pro- |Chaldron - worked. |action.| | | duced. |of Coal. - ---------+-------+----------------+----------------+--------+--------- - | |_Chal- _Bushel._|_Chal- _Bushel._| _Cubic | _Cubic - | |dron._ |dron._ | Feet._| Feet._ - Monday | 87 | 10 30 | 4 24 | 94,987| 8,768 - Tuesday | 88 | 14 24 | 6 8 | 128,597| 8,784 - Wednesday| 88 | 14 24 | 6 8 | 122,188| 8,331 - Thursday | 94 | 15 24 | 6 26 | 131,176| 8,373 - Friday | 96 | 16 0 | 6 32 | 127,696| 7,981 - Saturday | 96 | 16 0 | 6 20 | 127,536| 7,971 - Sunday | 96 | 15 18 | 6 4 | 125,487| 8,092 - | +----------------+----------------+--------+--------- - | | 103 12 | 43 14 | 857,667|8,300[18] - =========+=======+================+================+========+========= - - [18] Average proportion of gas from a chaldron of coal. - -_Expenditure of Process A._ - - Coals, decomposed, 103 chaldron 12 bushel, at £ 2. 11_s._ - 6_d._ the chaldron, (27 Cwt.) £ 266 2 0 - - Small Coal, 43 chaldron, 14 bushels, used for fuel, at £ 2. - 2_s._ the chaldron 91 2 4 - - Wages of two additional workmen (not required had the - retorts been worked at eight hours charges,) at £ 1. 16_s._ - each man, the week 3 12 0 - ----------- - Total expenditure, £. 360 17 0 - -_Products of Process A._ - - Coke, 103 chaldron, 12 bushel, at £ 1. 7_s._ the chaldron £ 139 10 0 - - Breeze, or small coke, 6 chaldron, 9 bushels, at 18_s._ the - chaldron 5 12 6 - - Tar, 7³⁄₄ tons, at £ 6. the ton 46 10 0 - - Ammoniacal liquor, 1864 gallons, at 1¹⁄₂_d._ the gallon 11 13 0 - - Gas, 857,667 cubic feet, at 15_s._ the thousand cubic feet 643 5 0 - ---------- - Total for products, £ 846 10 6 - -Hence the amount of expenditure for procuring 857,667 cubic feet of gas, -is £ 360. 17_s._ - -The value of the saleable products £ 846. 10_s._ 6_d._ - -And the average proportion of gas obtained from one chaldron of -Newcastle coal, 8,300 cubic feet. - - -_Process B._ - - =========+=======+================+================+========+========= - Number of| Number| | |Quantity| Propor- - Days the | of |Quantity of Coal| Quantity of | of | tion of - Retorts |Retorts| decomposed for | Coal used | Gas | Gas to a - were | in | obtaining Gas. | for Fuel. | pro- | Chaldron - worked. |action.| | | duced. |of Coals. - ---------+-------+----------------+----------------+--------+--------- - | |_Chal- _Bushel._|_Chal- _Bushel._| _Cubic| _Cubic - | |dron._ |dron._ | Feet._| Feet._ - Monday | 57 | 9 18 | 2 13 | 94,987| 10,000 - Tuesday | 77 | 12 31 | 3 8 | 128,597| 10,000 - Wednesday| 73 | 12 8 | 3 2 | 122,188| 10,000 - Thursday | 79 | 13 4 | 3 10 | 131,176| 10,000 - Friday | 76 | 12 27 | 3 7 | 127,696| 10,000 - Saturday | 77 | 12 27 | 3 6 | 127,536| 10,000 - Sunday | 76 | 12 20 | 3 6 | 125,487| 10,000 - | +----------------+----------------+--------+--------- - | | 103 12 | 21 16 | 857,667| 10,000 - | | | | | [19] - =========+=======+================+================+========+========= - - [19] Average proportion of gas from a chaldron of coal. - -_Expenditure of Process B._ - - Coal, decomposed, 85 chaldron, 27 bushels, at £ 2. - 11_s._ 6_d._ the chaldron £ 220 16 10¹⁄₂ - - Small Coal, 21 chaldron, 16 bushels, used for fuel, at - £ 2. 2_s._ the chaldron 45 0 8 - --------------- - Total expenditure, £. 265 17 6¹⁄₂ - -_Products of Process B._ - - Coke, 100 chaldron, at £ 1. 7_s._ the chaldron £ 135 0 0 - - Breeze, or small coke, 3 chaldron, at 18_s._ the chaldron 2 14 0 - - Coal tar, 6 Tons, 8 Cwt. at £ 6. the ton 38 8 0 - - Ammoniacal liquor, 1536 gallons, at 1¹⁄₂_d._ the gallon 9 12 0 - - Gas, 857,667 cubic feet of, at 15_s._ the thousand cubic - feet 643 5 0 - ------------ - Total for products, £. 828 19 0 - -From the result of this process it appears, that at the expence of -265_l._ 17_s._ 6¹⁄₂; the value of the products obtained is £ 828. 19_s._ - -By comparing the two preceding processes, A and B, it will be observed -that the same quantity of gas was generated each day, notwithstanding -there were fewer retorts in use, and less coal decomposed by process B, -than by Report A, and that the expence of fuel, when the distillatory -process was continued for a term of eight hours, was considerably less. -Also, that the proportion of gas obtained from a chaldron of coals, was -greater than when the process was continued for only six hours. - -Hence, if from the products of - - process A, £. 846 10 6 - we take the products of process B, £. 828 19 0 - ----------- - The difference is, £. 17 11 6 - -which, being subtracted from the difference between the expenditure, as -specified in the process alluded to, namely - - Process A, £. 360 17 0 - - Process B, 265 17 6¹⁄₂ - --------------- - The difference is £. 94 19 5¹⁄₂ - - Less 17 11 6 - --------------- - And leaves a balance of £. 77 17 11¹⁄₂ - -in favour of _working eight hours charges_, for one week, and producing -a like quantity of gas, as had been obtained by working _six hours -charges_. - -Thus, having compared the quantity of coals actually used when working -six hours charges, with what was used to produce a like quantity of gas -from eight hours charges, I shall next point out, in process C, the -quantity of gas obtained when working the same number of retorts for a -period of eight hours which had been worked at the process of six -hours. - - -_Process C._ - - =========+=======+================+================+=========+======== - Number of| Number| | | Quantity|Propor- - Days the | of Re-|Quantity of Coal| Quantity of | of Gas |tion of - Retorts | torts | decomposed for | Coal used | pro- |Gas to - were | [20] | obtaining Gas. | Fuel. | duced. |a Chal- - worked. | in | | | |dron of - |action.| | | |Coals. - ---------+-------+----------------+----------------+---------+-------- - | |_Chal- _Bushel._|_Chal- _Bushel._| _Cubic |_Cubic - | |dron._ |dron._ | Feet._ |Feet._ - Monday | 87 | 16 18 | 3 22 | 165,000| 10,000 - Tuesday | 88 | 14 24 | 3 24 | 146,667| 10,000 - Wednesday| 88 | 14 24 | 3 24 | 146,667| 10,000 - Thursday | 94 | 15 24 | 3 33 | 156,666| 10,000 - Friday | 96 | 16 0 | 4 0 | 160,000| 10,000 - Saturday | 96 | 16 0 | 4 0 | 160,000| 10,000 - Sunday | 96 | 15 18 | 3 32 | 155,000| 10,000 - | +----------------+----------------+---------+-------- - | | 107 0 | 26 27 |1,070,000| 10,000 - | | | | | [21] - =========+=======+================+================+=========+======== - - [20] Worked at six hours charges in process A, page 85, but here - worked at eight hours charges. - - [21] Average proportion of gas from a chaldron of coal. - -_Expenditure of process C._ - - Coal decomposed, 107 chaldron, at £ 2 11_s._ 6_d._ the - chaldron £ 275 10 6 - - Small coal, 26 chaldron, 27 bushels, used for fuel, at £ 2 - 2_s._ the chaldron 56 3 6 - ---------- - Total expenditure £ 331 14 0 - -_Products of process C._ - - Coke, 124 chaldrons, at £ 1 7_s._ the chaldron £ 167 8 0 - - Breeze, or small coke, 4 chaldrons, at 18_s._ the - chaldron 3 12 0 - - Tar, 8 tons, at £. 6 the ton 48 0 0 - - Ammoniacal liquor, 1945 gallons, at 1¹⁄₂_d._ the gallon 12 3 1¹⁄₂ - - Gas, 1,070,000 cubic feet, at 15_s._ for a thousand cubic - feet 802 10 0 - ------------- - Total for products £ 1033 13 1¹⁄₂ - - -RECAPITULATION. - - Products by process C. £ 1033 13 1¹⁄₂ - - Products by process A. 846 10 6 - ------------- - Difference £ 187 2 7¹⁄₂ - - Expenditure by process A. £ 360 17 0 - - Expenditure by process C. 331 14 0 - ---------- - Difference £. 29 3 0 - -From the above recapitulation it will appear, that by working equal -numbers of retorts, at six and at eight hours charges, the balance is -considerably in favour of the latter method; for, from the foregoing -statement, there appears to be on the practice of the latter method an -increase of saleable products amounting to - - £ 187 2 7¹⁄₂ - obtained at 29 3 0 less expence; - consequently there is a ------------- - balance of £ 216 5 7¹⁄₂ in favour of - -working the retorts, as stated in process C, over that method shewn in -process A; and in such proportion, _let the number of retorts worked be -what it may, an advantage will always be gained in this mode of -manufacturing coal gas, by working the retorts at eight hours charges, -as the workmen call it, in preference to adopting the shorter process_. - -From a series of operations made[22] with twenty parallelopipedal and -with twenty cylindrical retorts, worked for one month, it has been -ascertained that the decomposition of coal is most economically -conducted when each retort is charged with 100 pounds of coal, and the -distillatory process be continued for eight hours. Two men, one by day -and one by night, can attend nine or ten retorts. - - [22] By H. Morrison, Esq. and Self; the coal used, was Newcastle - (Bewick and Craister’s Walls End) coal. - - - - -PART VI. - - -_Temperature best adapted for working Cylindrical Retorts._ - -There is perhaps no subject in the art of manufacturing coal gas, on -which practical men are less agreed, than they are on the temperature -most economically to be employed for the production of coal gas in the -large way. It must be sufficiently evident, that cast-iron retorts, when -worked at a low temperature, will last longer, than when exposed to -higher degrees of heat.[23] Hence, according to some operators, the -economy of the process consists in saving the retorts, at the expense of -a diminution, even though considerable, in the quantity of gas -obtained; whilst, according to others, it is more economical to obtain -the largest possible quantity of gas at the expence of any consequent -injury to the distillatory vessel. - - [23] It is essential that the retorts should be kept in constant - action night and day, or at least never allowed to go below a red - heat. The first portion of oxide which forms upon the surface, when - allowed to cool, cracks and falls off, leaving a new surface to be - acted upon the next time it is heated. By thus being every day heated - and cooled, a retort will be speedily destroyed. - -The truth appears to be wholly with neither of these extremes, nor -indeed in any absolute general rule which can be ventured on the -subject. - -The degree of temperature proper to be adopted in gas works, where the -method of decomposing coal in masses, or layers from four to eight -inches in thickness, and upwards, is practised by means of the cast-iron -retorts, of which a description has been given, p. 53, chiefly depends -on circumstances of a local nature, with regard to the price of coal and -labour, so that where in one place it may be more profitable to employ a -very high temperature for the production of the gas, it may be in others -quite the reverse. - -The utmost therefore that can be done on this head, is to state what -these circumstances are, and to shew the value which belongs to them -under every supposable situation. - -In this metropolis, and in all other places where coal and labour bear a -higher price than probably elsewhere in this country, and where saving -of time is also an object of primary importance, it is clearly -established, that the manufacturer who pursues the method of decomposing -coal in masses from five to eight inches and upwards in thickness, by -means of cast-iron retorts,[24] will consult his interest best, by -employing such a high temperature for the decomposition of the coal, as -will produce in the shortest time the greatest possible quantity of gas, -from a given quantity of coal, without regarding the unavoidable -deterioration of the retorts. But in places where coal and labour is -cheap, it will be his interest to save the retorts at the expence of the -coal. But that this fact may not rest on mere general assertion, I shall -subjoin for the satisfaction of the reader a few statements of -experiments made upon a large scale for the purpose of ascertaining -these facts. - - [24] The Retorts should be manufactured of what is called in commerce, - _iron of the second process_. The best cast-iron of this kind, is of a - light grey colour, its fracture is granulated and dull, it receives a - dent from the blow of a hammer. The cast-iron which exhibits a dark - grey or black colour inclining to blue, and presents granular - concretions, readily friable, and therefore unfit for vessels intended - to stand a long continued heat. - - -_Annual Creditor and Debtor Account of manufacturing daily from 50,000 -to 102,000 cubic feet of gas at the price which coal bears in the -metropolis.--The operation being commenced with new Retorts, and the -retorts being left in a fit working state._ - -The first of the following processes was conducted on the principle that -coal and labour, being of an high price, as in London, it is most -economical to obtain the greatest possible quantity of gas from a given -quantity of coal in the least possible time, without any regard to the -injury done to the distillatory vessel. - -The second process is intended to illustrate the correctness of that -principle, by shewing that where coal and labour are at the high prices -stated in the first process, it is a losing system to work the retorts -at a lower temperature, in order to make them last longer. - -In some respects a similarity will be observed between these -experiments, and those already given in page 85, but besides their -having reference to the separate and distinct circumstance of the high -prices of coal and labour in London, it will be found that they also -differ from the former statements, in exhibiting, not merely the expence -of working, but the original cost of erecting the retorts, as well as -the expence of replacing them. - - -_Process I._ - -The quantity of gas to be supplied each night, was 50,000 cubic feet. - -In order to produce this quantity, thirty cylindrical retorts, each -containing two bushels of Newcastle coal, were put in action. The -temperature at which the retorts were worked, was a bright cherry -redness, at which they produced at the rate of ten thousand cubic feet -of gas, from a chaldron of Newcastle coal. - -To work the retorts, three workmen by day and three by night, were -required. - -The retorts were charged three times every twenty-four hours. The first -total expence of erecting the retorts, was £. 23 each, and it was found, -that when worked night and day, they could not, with the utmost care, -be made to continue fit for use for more than from five to six months; -hence, a double set of the original number of retorts was requisite each -year. - -The whole annual operation pursued on this plan stood as follows: - - Cost of sixty retorts, thirty at work and thirty to - spare, with brick-work foundation, iron coke hearth, - perpendicular pipe connected with hydraulic main, see P, - fig. 2, plate IV., at £ 23. each. £. 1380 0 0 - - Six workmen, three during day-time, and three at night, - at £ 1. 6_s._ each the week 405 12 0 - - Coals, 1825 chaldron, requisite for producing the gas, - at £ 2. 8_s._ the chaldron 4380 0 0 - - Wear and tear of grate bars, fire-shovels, tongs and - rackers 42 0 0 - - 456¹⁄₄ chaldron of Coal for fuel, £. 2 1_s._ the chaldron £. 935 6 3 - ------------ - Total expence, £. 7142 18 3 - - Subtract the market price of saleable - Coke[25] produced by the process, viz. 1825 - chaldron, at £ 1. 3_s._ the chaldron £. 2098 15 0 - - 456¹⁄₄ chaldron of small Coke or Breeze, at - ten shillings the chaldron 228 2 6 - ------------ 2326 17 6 - ------------ - There remains £. 4816 0 9 - -for the annual expence of maintaining the apparatus on this -construction. - - [25] The tar and ammoniacal liquor afforded by the process, not being - always saleable articles, are omitted to be charged in the estimates. - - -_Process II._ - -The next experiment made was, to ascertain the contrary practice of -operating, namely the mode of working the retorts, on the principle -which holds out, that it is more economical to be satisfied with a less -quantity of gas than what the coal is capable of furnishing, because by -so doing the retorts become less deteriorated and remain for a longer -time in a state fit for use. - -The quantity of gas to be supplied each night, was, as in the preceding -process, fifty thousand cubic feet. - -The number of retorts required to produce that quantity, was forty-two, -and to make them last twelve months instead of six months, as in the -preceding process, it was necessary to work them at a temperature, at -which a chaldron of coal produces from seven thousand, to eight thousand -cubic feet of gas. - -The result of this operation was as follows: - - Cost of forty-two retorts, with brick-work foundation, - cast-iron coke hearth, perpendicular dip pipe, connected - with the hydraulic main, at £. 23 each £. 966 0 0 - - Eight workmen, four by day and four by night, at £ 1. - 6_s._ each the week £. 540 16 0 - - 2555 chaldron of Coal, requisite for producing the gas, - at £. 2 8_s._ the chaldron £. 6123 0 0 - - Wear and tear of grate bars, fire shovels, tongs and - rackers 42 0 0 - - 638 chaldron of Coal for fuel, at £ 2. 1_s._ the - chaldron 1307 18 0 - ------------ - £. 8979 14 0 - - Deduct the market price of 2555 chaldron - of coke, produced by the process, at £ 1. - 3_s._ the chaldron. £. 2938 5 0 - - 638³⁄₄ chaldron of small coke, or breeze, - at 10s. the chaldron 319 7 6 - ------------ £. 3257 12 6 - ------------ - - There remains for the annual expence of maintaining the - apparatus £. 5722 1 6 - - Subtract the annual expence of Process I. 4816 0 9 - ------------ - The balance in favour of Process I. is £. 906 0 9 - - -_Process A._ - -In the following additional processes, the retorts when begun to be -worked, were also new, and were left in a fit working state. The -quantity of gas required to be produced daily, was 102,000 cubic -feet.[26] - - [26] These Experiments were made at the Westminster Gas Works, under - the superintendance of Mr. Clegg, to whom I am indebted for this - communication. - -The retorts were worked at a temperature at which they produced 10,000 -cubic feet of gas from the chaldron, (27 Cwt.) of Newcastle coal. - - To sixty-eight retorts, twice replaced, at £ 15. each £. 2040 0 0 - - Deterioration of grate bars, fire shovels, tongs, and - rackers 91 16 0 - - 3723 chaldron of coal for obtaining the gas, at £ 2. - 8_s._ the chaldron 8935 4 0 - - 930 chaldron, 27 bushels of Coal, for fuel, at £ 2. - 1_s._ the chaldron 1908 0 9 - - 14 Men at £ 1. 6_s._ each, the week, being 7 for the - day, and 7 for the night 946 8 0 - ------------- - £. 13,921 8 9 - - Deduct the market price of 3723 chaldron - of saleable coke, at £ 1. 3_s._ the - chaldron £. 4281 9 0 - - 930³⁄₄ chaldron of small coke, or breeze, - at 10_s._ the chaldron 465 7 6 - ------------ £. 4746 16 6 - ------------ - Cost of obtaining, 37,230,000 cubic feet of gas £. 9174 12 3 - - -_Process B._ - -Producing 8000 cubic feet of gas, from the chaldron of Newcastle coal. - - Eighty-five retorts, once replaced at £. 15 each £. 1275 0 0 - - Deterioration of grate bars, fire shovels, tongs and - rackers 117 16 0 - - 4653 chaldron of coals for obtaining the gas, at £ 2. - 8_s._ the chaldron 11,167 4 0 - - 1163³⁄₄ chaldron of coal for fuel, at £ 2. 1_s._ the - chaldron 2385 13 9 - - Eighteen men at £ 1. 6_s._ each man the week, being nine - for the day, and nine for the night 1216 16 0 - -------------- - £. 16,162 9 9 - From which deduct 4653 chaldron of - saleable Coke, at £. 1 3_s._ the chaldron £. 5350 19 0 - - 1163³⁄₄ chaldron of small coke, or breeze, - at 10_s._ the chaldron 581 17 6 - ------------ £. 5932 16 6 - -------------- - Cost of obtaining 37,230,000 cubic feet of gas, - according to process B, £. 10,229 13 3 - - Deduct the cost of Process A, 9174 12 3 - -------------- - Balance in favour of Process A. £. 1055 1 0 - -The reader will have no difficulty in calculating from the preceding -experiments, every variation which can possibly take place, as to the -degree of temperature most economically to be employed in consequence -of a variation in the prices of coal, coke and labour.[27] - - [27] The average cost at which coal gas can be manufactured on a large - scale in London, is seven shillings the thousand cubic feet, deducting - not only the interest of the capital sunk in erecting the - establishment, rent and taxes, the cost of the coal, labour, wear and - tear of the machinery, and superintendence, but all other necessary - and incidental expences that may occur. - - -_Comparative facility with which the decomposition of different species -of Coal is effected._ - -The temperature necessary for the decomposition of different kinds of -coal, varies. Some species of coal are more readily decomposed, and -require a less portion of fuel than others; they yield up their maximum -quantity of gas, in an almost equal stream from beginning to end, and no -extraordinary increase of temperature is required to terminate the -distillatory process. Other kinds of coal require a different treatment; -the temperature necessary to complete their decomposition requires that -the heat should be considerably increased as the process advances; and -without this condition the evolution of the gas would cease altogether. - -A striking proof of this statement may be seen when Newcastle or -Sunderland coal are attempted to be decomposed at a temperature which is -sufficient for the decomposition of Scotch Splent coal, or Lancashire -Wiggan coal. - -The decomposition of the latter, will be fully effected when the -distillatory vessel exhibits to the eye a dull cherry redness, and the -evolution of the gas at such a temperature will take place in torrents -from beginning to end. In order, on the other hand, to complete the -decomposition of Newcastle and Sunderland coal, the heat must be -increased as the process proceeds, and the production of the gas will be -extended far beyond the time required for decomposing a like quantity of -Scotch, or Lancashire Wiggan coal, when exposed to the same degree of -heat. - -It must be allowed, however, that few experiments have been yet made on -this subject. I have reason to believe that all those varieties of coal -which afford an incoherent friable coke, are decomposed at a much lower -degree of heat, than such as produce, when treated under like -circumstances, a ponderous compact coke. And if we give credit to the -assertion of those workmen, whose business it is to manufacture a given -quantity of gas by means of a certain quantity of coal delivered to -them, it would appear that coal which affords gas abounding in -sulphuretted hydrogen, is the kind of coal most easily to be decomposed. -This, as far as it regards the decomposition of Scotch Splent or cannel -coal, is certainly true. No species of coal affords gas at a lower -temperature, and of none is the gaseous product more loaded with -sulphuretted hydrogen gas. The subject is important and deserves to be -pursued; particularly in places where coke is not, as it is in the -metropolis, and all places where coal bears a high price, next to gas, -the primary article to which the attention of the manufacturer of coal -gas ought to be directed. - -The following are the result of a series of experiments on the subject -made at the Westminster Gas Works,[28] the same temperature being -employed throughout the process. - - [28] Communicated by Mr. T. S. Peckston. - - Varieties of Coal. Ratio of time - in Decimals. - Scotch Splent or Cannel coal 1,00 - Newcastle coal, (Nesham) 1,04 - Gloucestershire coal - Forest of Dean first variety (Low Delph) 1,08 - Newcastle coal, - Second variety, (Middle Delph) 1,09 - Third variety, (Heaton Main) 1,15 - Fourth variety, (Brown’s Wall’s End) 1,18 - Fifth variety, (Hutton’s Low main) 1,30 - Sixth variety, (Tyne Main) 1,54 - Warwickshire coal, - First variety, 1,60 - Second variety, 1,65 - Third variety, 1,68 - - - - -PART VII. - - -_Horizontal Rotary Retorts, lately brought into use for manufacturing -coal gas._ - -The many disadvantages attendant on the plan of decomposing coal in -masses from five to ten inches in thickness, as already sufficiently -exposed in the preceding parts, had naturally the effect of developing a -principle of manufacturing coal gas, which practice has now fully -established, namely: that to decompose coal, in thin layers from two to -four inches in thickness, is to obtain the greatest quantity of gas from -a given quantity of coal at the least expence. - -Mr. Clegg was the first person who pointed out to the public the -advantages that must accrue from this mode of operating, and to him we -are indebted for the construction of an apparatus, the great ingenuity -and superiority of which, entitles what is called the horizontal rotary -retort, to all the merit and praise that belongs to the character of an -original invention. - -The numerous and great advantages of this distillatory apparatus, the -rapidly increasing adoption of it,[29] and the almost certain prospect -which exists of their ultimately superseding all former methods of -decomposing coal, make it proper that I should lay before the reader, as -full an account as my limits will permit, of the construction and -operation of this retort, and the mode of applying it; and this becomes -the more necessary on account of the many important improvements which -the apparatus has undergone since its first adoption,[30] and of which -no description has yet been laid before the public. - - [29] Retorts of this description have been lately adopted, in the Gas - Works at Bristol, Birmingham, Chester, Kidderminster, and at many - other provincial Gas Establishments. - - [30] An account of the original construction of the rotary retort may - be seen in the Repository of Arts, No. CLXXVI, 1816, page I. and also - in the Journal of Science, Vol. II. page 133. - -The following account will render the construction of this retort -sufficiently obvious: - - -_Description of the Horizontal Rotary Retorts at the Royal Mint._[31] - - [31] The retorts lately erected at the Gas Works, at Birmingham, - Chester, Bristol, &c. are similar to those at the mint. - -The horizontal rotary Retorts at the Royal Mint, are hollow cylinders, -eight feet six inches in diameter and 15 inches high, arched a little at -the top. They are made of wrought-iron plates, half an inch thick, -rivetted together in the manner of a steam-engine boiler; A, A, A, fig. -2, plate III. exhibits a perpendicular section of the rotary retort. In -fig. 1, plate II. the retort is seen fixed in the brick-work; _a_, fig. -1, plate II. shews the mouth of the retort, through which the coals are -introduced, and from whence the coke is withdrawn. It is also shown in -perspective at B, B, B. fig. 2. plate VII. The mouth is closed with a -cast-iron door fitted on air-tight by grinding. - -The door is connected at its upper and lower extremities, with a frame -and adjusting rod, see B, B, fig. 1, plate II., and also plate VII., by -means of which it may readily be slided down below the mouth of the -retort, when the coals are to be introduced, or coke is to be withdrawn. -To the upper extremity of the rod B, fig. 1, plate II., is fixed a -lever, loaded with a counterpoise weight C, to balance the door, and to -render the opening and closing of it easy and expeditious. - -The mouth-piece and its door is three feet long, and nine inches wide; -it projects nine inches beyond the brick-work or furnace in which the -retort is fixed, as may be seen at fig. 1, plate II. - -The fire-place, which is on the opposite side to that of the mouth of -the retort, heats only one-third part of the whole capacity of the -retort to that degree which is proper for the complete and rapid -decomposition of the coal, while the remaining parts, which are not over -the fire-place, and to which the fire flues do not extend, are kept at a -lower temperature. - -The flues are directed under about one-third of the area of the bottom -of the retort, and after having passed over one-third part of the area -of the top of the retort, they pass into the chimney. Fig. 1, plate VI., -exhibits the direction of the flues; A, A, the flues, and the -fire-place. The whole retort is guarded from the contact of the fire, -which would soon destroy it, by fire-bricks; it notwithstanding speedily -receives the full effect of the heat, and retains its temperature when -once heated for a long time. Fig. 1, plate II., exhibits one of the -retorts fixed in its furnace. A perspective view of three retorts may be -seen in fig. 2, plate VII. - -Through the centre of the retort, passes perpendicularly, an iron shaft -D, as shown in the section of the retort, fig. 2, plate III., and also -in fig. 1, plate II. The lower extremity of the shaft revolves upon the -bottom of the retort, in a cup-shaped cavity, while its upper extremity -passes through the roof of the retort, where the latter is made -air-tight by means of a pipe E, fig. 1, plate II., and E, fig. 2, plate -III., closed at the top and surrounding the shaft, and hence the shaft -must always preserve its centre. - -To the lower extremity of the shaft is keyed a box or centre piece, -(technically called a rose centre,) F, fig. 2, plate III. It is also -seen in the perpendicular section of the retort, fig. 1, plate II. From -this shaft radiate twelve wrought-iron arms, G, G, fig. 2, plate -III.,[32] fixed in sockets made in the box. These arms are elevated -three inches above the bottom of the retort, and extend to nearly within -its whole inner circumference. They are wedge-shaped, and their greatest -diameter is at right angles to the base of the retort, so that the -weight of the arms rests on the axis. They are intersected by two -concentric rings, as will be seen on inspecting fig. 5, plate III., -which exhibits the plan of the retort, together with the iron arms, G, -G, and concentric rings. The centre of figure 5, shows also the plan of -the rose centre F, fig. 2, plate III., into which the arms are keyed. - - [32] In the horizontal rotary Retorts at the Chester, Birmingham and - Bristol Gas Works, which are twelve feet six inches in diameter, there - are fifteen arms. At some Gas Works the arms are made of cast-iron. - -Between the arms are placed twelve shallow iron trays or boxes, destined -to contain the coal from which the gas is to be obtained. They are -formed to the segment of a circle, hence the whole series of them when -arranged in the retort, exhibits a shallow circular tray, which, when -motion is given to the shaft, may be made to revolve within the retort. - -Fig. 12, plate III. exhibits one of the shallow trays, or coal boxes in -perspective. - -It will be obvious, that by the motion of the shaft, any number of the -trays or coal-boxes can readily be brought from the coldest, into the -hottest, and from the hottest into the coldest part of the retort. - -H, fig. 1, plate II., and _a_, plate III., or H, plate VII., is a -perpendicular pipe situated at the margin of the retort, close behind -the mouth-piece, and consequently in the coldest part of the retort. It -serves to carry off the distillatory products evolved from the coal, and -causes part of the vaporous tar, which becomes condensed in it, to -trickle back again upon the coal in the retort, in order to become -converted into gas, when the coal on which it falls becomes situated -over the fire-place. - -This pipe is furnished at its upper extremity with a _hydraulic valve_, -J, fig. 1, plate II. It consists simply of an inverted cup X, applied -over the upper open extremity of the perpendicular pipe H, and submersed -into a cup formed of a portion of larger pipe, surrounding the pipe H, -containing tar. The smaller, or inner cup X, is represented in the -design raised out of the liquid contained in the outer cup J, to show an -aperture Y, made in the smaller or inner cup; the use of which will be -mentioned hereafter. The inverted cup X, is furnished with a chain, one -extremity of which is fastened to the upper extremity of the cup, the -other passes over a small wheel, and descends through the roof of the -building, as shown in the design. - -K, fig. 1, plate II., or K K, fig. 2, plate VII., is a branch pipe -proceeding laterally from the perpendicular pipe H; it communicates with -the hydraulic box L, fig. 1, plate II. N, is a pipe which proceeds from -the hydraulic box L; it serves to carry away the gaseous and liquid -products to their places of destination. The liquid products, namely, -the tar and ammoniacal fluid, become deposited in the tar cistern, fig. -3, plate II., into which the pipe N terminates. The tar cistern is -furnished with two floats Y Y; the one serves to indicate the quantity -of tar, and the other the quantity of aqueous ammoniacal fluid contained -in the vessel. These fluids may be drawn off without admitting air into -the vessel by the stop-cock and bent tube, exhibited in the figure. - -The shorter pipe N, which proceeds from the tar cistern, fig. 3, plate -II., and communicates with the purifying apparatus or lime machine, fig. -2, plate II., serves to convey the gaseous fluid, which accompanied the -condensible liquids deposited in the tar cistern, back again into the -lime machine, or purifying apparatus, fig. 2, plate II., the -construction of which, together with the conveyance of the gas from this -vessel to its place of destination will be stated hereafter. - -L, fig. 1, plate II., or fig. 2, plate VII., is an iron flap table, -placed level with the bottom of the mouth of the retort. It is -convenient to hold several coal trays ready charged with coal in a state -fit to be introduced into the retort. - -The fire-place, flues, and ash-pit of the furnace, in which the retort -is fixed, are sufficiently obvious by mere inspection of fig. 1, plate -II. The front elevation of the retort is seen in fig. 2, plate VII., -which exhibits three horizontal retorts; two of which have the door of -the mouth-piece slided down, and one with the door in its place, or -shut. The circular ring seen in this design, at the top of each retort, -which rests on iron-bearing bars, the extremities of which are let into -the end walls of the furnace, serves to support the roof of the retort -by means of bolts, proceeding from the inner side of the roof. This -arrangement is likewise shown in the section, fig. 1, plate II.[33] At -the bended part of the perpendicular pipe H, fig. 1, plate II., is seen -a bonnet, or cover, which closes an opening made into the pipe H, -through which, by means of an iron rod, the lower extremity of the pipe -H, may, from time to time, be examined, to guard against an incrustation -of decomposed tar or carbonaceous matter that might happen to accumulate -in that part of the pipe. The upper part of the pipe H, above the bonnet -at the bended part, requires no examination. - - [33] A more economical method of supporting the roof of the retort has - lately been adopted by Mr. Clegg. It consists in giving the roof the - form of an inverted arch, supported on the Catenaria plan, by two - bolts only, placed at the most elevated extremity of the arch and - secured to an horizontal beam. - -_b_, fig. 2, and _b_, fig. 5, plate III., is the flanch of the retort; -_c_, fig. 2, plate III., the flanch of the mouth-piece; _d_, the cutter, -or wedge, which draws the mouth-piece close; _e_, the cross bar, against -which the cutter _d_, bears, to render the mouth-piece air tight; _f_, -fig. 2, one of the eye-bolts or arms which support the cross bar _e_; it -is also seen at _e_, in the plan of the retort, fig. 5, plate II. In -this figure _b_ is the flanch of the retort, and _c_ the door. - -These few particulars will be sufficient to enable the reader to -understand the construction of the retort; its action is as follows. - - -_Action and Management of the Horizontal Rotary Retort._ - -When the retort is heated to the proper temperature for the -decomposition of the coal, the door is slided down, and the coal boxes -charged with small coal are slided into the retort from the table, L, -fig. 1, plate II., one by one, so that each box rests firmly upon the -concentric rings placed between the arms of the retort; the door is then -slided up again into its place and rendered air-tight by means of -wedges. - -When the whole circle fig. 5, plate III. is thus filled with -coal-boxes, (the coal should be spread in the boxes, in layers two or -three inches in depth,) it is obvious that of all the twelve boxes, four -only can be situated directly over the fire-place, while the remaining -eight are placed right and left towards the door of the retort. The coal -in the former boxes receives the full effect of the heat, (see the plan -of the fire flues of the retort, fig. 1, plate VI.,) while the remaining -eight boxes to which the fire does not extend, are less heated. The coal -in the four boxes which are in the hottest part of the retort becomes -rapidly decomposed, whilst the coal in all the other boxes is gradually -heated, and consequently deprived only of moisture, previous to being -subjected to the greatest heat. The box which is situated under the -condensing pipe H, plate II., near the entry door, receives the -condensed tar which trickles down the pipe H. - -Now let us suppose that the coal in the four boxes over the fire place -is fully decomposed, which will be the case if 32¹⁄₂ pounds of coal are -in each box, in two hours, the workman then turns the shaft E, fig. 1, -plate II., one-third part of the circumference of a circle, by pulling -towards him by means of an iron hook the nearest iron arm that may -happen to be opposite to the door; this moves those boxes which at the -commencement of the operation were over the fire-place, towards the -coldest part of the retort, namely, towards the door which is opposite -to the fire-place, and a second series, or four of the adjacent boxes, -are brought in turn into the hottest part of the retort, or over the -fire-place, from whence the preceding boxes were removed. - -When the coal in the second series of boxes has been two hours in the -hottest part of the retort, its decomposition will be completed; the -workman therefore turns the shaft again one-third part of a circle, and -a third series advances in their place, while at the same time the first -series becomes situated opposite the entry door of the retort, from -whence they may be withdrawn and exchanged for an extra set of trays, -ready charged with coal and placed on the iron table for that purpose. - -In this manner the operation proceeds. One-third part of the whole -charge of coal within the retort is always in the act of becoming -decomposed; another third part is gradually heated, and totally deprived -of moisture, previous to its being exposed to the temperature necessary -for its decomposition; and the remaining third part placed in the -coldest part of the retort, receives that portion of tar, which escapes -decomposition, and trickles down the perpendicular pipe, in order to be -decomposed when the coal upon which it falls becomes situated over the -fire-place. Hence the quantity of tar obtained from one chaldron of -Newcastle coal, when decomposed by means of an horizontal rotary retort, -seldom amounts to more than sixty or seventy pounds, whereas the same -quantity of coal when decomposed by means of cylindrical or -parallelopipedal retorts, yields never less than from one hundred and -fifty, to one hundred and eighty pounds. An horizontal rotary retort, -twelve feet six inches in diameter, and fifteen inches high, furnishes -in the ordinary way of working every twenty-four hours, fifteen thousand -cubic feet of gas, when five trays of the retort are charged with three -bushels of Newcastle coal. The weight of the retort is three tons; its -capacity, one hundred and fifty cubic feet. - -The hydraulic valve described page 116, serves merely to restore the -equilibrium, between the gas within the retort, and the atmospheric air -without, previous to the opening of the door of the mouth of the retort. -To effect this the workman raises the cup X, by means of the chain, so -that the small hole Y, in the cup X, becomes raised out of the tar in -the cup L, and he closes it again when the retort is charged: this -operation requires two minutes. We have stated already, that the door of -the retort is ground air-tight, and hence it requires no luting. - - -_Advantages of the method of manufacturing Coal Gas by means of -Horizontal Rotary Retorts._ - -The advantages of the mode of manufacturing coal gas by means of -horizontal rotary retorts, consist in a saving of fuel, time, labour, -and machinery, a gain in the quantity of gas, and increase in the -quantity of coke. - -_Saving of fuel._--The mass of coal subjected to decomposition being -reduced from the dimension required in the old plan (by means of -cylindrical retorts) to the narrowest available limits, there being no -outward crust of coke to be kept red hot for hours to no purpose, while -the decomposition of the interior mass of coal is going on;--the coke -itself being as soon as formed removed from the source of heat, and -applied while cooling, to warm up a fresh supply of coal next in order -of becoming decomposed, instead of being discharged in a red hot state, -into the open air, as requires to be done in the practice before -detailed--the whole fuel in short being necessarily and beneficially -expended--the saving of coal employed as fuel in this respect, is -exactly the gaining of all that is lost on the plan of employing -cylindrical or any of the retorts before described. Hence one chaldron -of coal is decomposed at the gas establishments where horizontal rotary -retorts are in action by means of twenty per cent of fuel, and at some -establishments an expert stoker will work the retorts with fifteen per -cent of fuel. - -_Saving of time._--The saving of time does not merely amount to what is -consequent on the speedier decomposition of the coal, and the saving of -that heat which formerly required to be kept up a length of time to no -adequate purpose; it also includes all that is gained in consequence of -the revolving motion to which the coal is submitted, superseding, as has -been already mentioned, the necessity of discharging the coke in an -ignited state from the retort. - -When the coke is removed, as previously explained, page 72, red hot from -the cylindrical, parallelopipedal, semi-cylindrical or ellipsoidal -retorts, the charging of the distillatory vessel with fresh coal -produces such a sudden reduction of temperature, that from three to four -hours inevitably elapse before the retort is again in a full working -state, and to this circumstance the workmen (perhaps very justly) -attribute the frequent sudden injury which the distillatory cast-iron -vessel sustains. - -Another striking advantage of the new mode of decomposing coal is, that -besides saving the time which is wasted in keeping up an intense -temperature unnecessarily the revolving apparatus prevents entirely the -loss occasioned by these three or four hours of unnecessary cooling of -the distillatory vessel. For each series of trays, or coal boxes, -containing the ignited coke, of the horizontal rotary retort, being -suffered to cool within the retort before the coke is discharged, and -being placed in contact with a fresh supply of coal, the temperature of -the retort is kept up uniformly the same from beginning to end. - -_Saving of Labour._--In consequence of the superior facility with which -the mode of decomposing coal in thin layers and removing the coke as -fast as it is formed is effected, the saving in point of labour is very -great. The charging and discharging of the retort is performed in two -minutes. Hence one chaldron of coal may be decomposed by means of three -horizontal rotary retorts, each twelve feet six inches in diameter, and -with the attendance of two men, in eight hours, and produces from -fifteen thousand, to eighteen thousand cubic feet of gas, whilst ten -thousand cubic feet of gas can only be obtained from the same quantity -of coal in eight hours, by means of twenty cylindrical retorts, attended -by the same number of workmen. - -_Saving of machinery._--When we compare the original cost and wear and -tear of the horizontal rotary retorts, with the cost and deterioration -of a set of cylindrical, parallelopipedal, ellipsoidal, or -semi-cylindrical retorts of an equal power, (that is to say to produce a -like quantity of gas, in a given time,) a difference not less striking -presents itself in favour of the horizontal retort. - -We have stated already, that cylindrical, ellipsoidal, parallelopipedal, -or semi-cylindrical retorts, when constantly kept in action, and worked -to the greatest advantage, cannot be made to last longer than six -months.[34] - - [34] They are frequently rendered unfit for use in three months, and - at some works in two months, owing not less to the irregularity of the - temperature at which they are worked, than to the carelessness of the - workmen. - -Only one-third part of the top and bottom plates of the rotary retort -being exposed to the action of heat, are alone liable to deterioration. -It is only necessary therefore that these parts of the vessel be -renewed, while the other parts remain uninjured for years. The new top -and bottom plates being rivetted to the old and undecayed part, without -deranging the rest, the retort is rendered as good as new. - -_Gain in the quantity of gas._--A large increase in the quantity of gas -obtained, is a natural consequence of the mode in which the -decomposition of coal is effected by means of the horizontal rotary -retort. - -Every body knows that coal, when decomposed slowly, affords a larger -quantity of tar and ammoniacal liquor, but a less quantity of gas than -when decomposed rapidly. - -In the former case, the formation of the proximate products which coal -is capable of furnishing is effected properly; the bituminous part of -the coal is developed under the most favourable circumstances. - -But when coal, after being previously deprived of moisture, is very -suddenly heated to a high temperature, in thin strata, and small -portions at a time, so that the vaporous products instead of becoming -condensed, are made to come into contact with a substance (which in this -case is the roof of the retort,) kept constantly at a temperature rather -higher than that at which gold, silver, and copper melts, (32°, -Wedgwood, or 5237°, Fahrenheit,) a very different arrangement of -principles takes place. - -The greatest portion of tar which the coal is capable of furnishing, -instead of being produced in a liquid form, becomes then decomposed into -carburetted hydrogen, and olifiant gas. That portion of tar which -escapes decomposition, is condensed in the perpendicular pipe _H_, fig. -2, plate II., or _H_, fig. 2, plate VII., and falls back again into the -retort, where it is also decomposed when the coal upon which it falls -comes under the process of decomposition. - -Hence the quantity of tar obtained by means of horizontal rotary -retorts, is very small; it seldom exceeds the proportion mentioned page -123, when the retort is worked to the greatest advantage. This quantity -is considerably diminished, when Newcastle coal, broken into pieces of -the size of split pease is decomposed in strata, not exceeding two -inches in thickness. The quantity of tar afforded by a chaldron of coal -then amounts to thirty pounds, whilst at the same time the quality of -the gas is improved; because coal tar furnishes olifiant gas, which the -coal alone, when distilled by means of cylindrical or other shaped -cast-iron retorts of the usual form, cannot produce, or at least but in -a small quantity. One gallon of coal tar yields 15 cubic feet of -olifiant gas, which greatly increases the illuminating power of the -carburetted hydrogen. - -From what has been so far stated, it will be understood why one chaldron -of Newcastle coal, when decomposed by the new process, may readily be -made to produce from 15,000 to 18,000 cubic feet of gas and upwards, -whereas the same quantity of coal, if decomposed by the old method, -yields only upon an average 10,000 cubic feet of gas.[35] - - [35] The experiments exhibiting the maximum quantity of gas obtainable - from coal, see page 44, were made with the horizontal rotary retorts - at the Royal Mint. Similar results have also been obtained at the - Westminster Gas-Works. - -In the former case, the greater part of the essential oil and tar which -the coal would have afforded is decomposed, as stated already by virtue -of the high temperature to which the vapourous tar is suddenly exposed -in the horizontal rotary retort, which is not the case when coal is -decomposed in the retorts of the old construction. - -_Gain in the quantity of coke._--With the cylindrical or cast-iron -retorts of the old shapes, the quantity of coke obtained from a given -quantity of coal is upon an average 25 per cent. increase by measure -from the best kind of Newcastle and Sunderland coal, but taking into -account the waste incurred in breaking out and removing the red hot coke -from the retort, which requires the application of rakers and crow bars, -a considerable portion of it becomes reduced to dust or breeze, and -hence no more than bulk for bulk of the coal decomposed can seldom be -depended upon as the ultimate saleable quantity of coke.[36] - - [36] There is a vast difference with regard to the quality as well as - quantity of coke obtained from different kinds of coal. Some kinds of - coal produce a species of coke which is so friable that it will hardly - bear being moved from place to place without crumbling into dust, - others produce coke in pieces of the size of small pebbles, while a - third sort affords coke of a stony hardness. - -In the new mode of carbonizing coal by means of the horizontal rotary -retorts, the increase of coke is 150 per cent. by measure, so that one -chaldron of Newcastle coal produces two and a half chaldron of -coke--this is the quantity produced upon an average. But when the retort -is worked at a temperature to produce at the rate of 18,000 cubic feet -of gas from the chaldron of coal, the increase of coke by measure is 175 -per cent.; in that case, the layers of coal in the coal boxes must not -exceed two inches in thickness, so that the volume of coke is in the -ratio of the quantity of gas produced and the rapidity and elevation of -temperature at which the decomposition of the coal is effected. - -The coke being withdrawn from the place where it is formed by merely -turning the boxes containing it, upside down, all waste is avoided. - -With respect, again, to the quality of the coke, it will be observed -that when the coal is rapidly carbonized in thin layers, and has full -liberty to expand freely, as in the case of the horizontal rotary -retort, it affords a light and porous coke, whereas in the cylindrical, -paralellopipedal, semi-cylindrical, or ellipsoidal retorts, the coke -being compressed, the intense heat to which it is so long and -superfluously exposed, renders it extremely dense, and of a stony -hardness. - -The latter sort of coke is unquestionably preferable for the smelter, -and all furnace operations, standing the blast of the bellows well. But -the coke produced in the new mode of operating, is better suited for -the great majority of domestic purposes, kindling more readily, and -making a more cheerful fire. The combustion of the dense, or as it is -now called, cylinder coke, can be only kept up when used in a common -grate, by a strong draft of air, and it is therefore not so well suited -for fuel for domestic purposes, to make a small fire; but the coke -obtained by the horizontal rotary retort, readily maintains its own -combustion, even when in small masses; hence it may be used without any -trouble, either in the fire-place of the cottager, or of the prince, and -accordingly it bears a higher price in the market. - - -_Directions to workmen, with regard to the management of Horizontal -Rotary Retorts._ - -The circumstance most essential to the economical application of the -horizontal rotary retort, is, as has been repeatedly stated, that the -coal shall be spread in thin layers in the boxes of the retort, not -exceeding from two to four inches in thickness; and it may be laid down -as a general rule, that the thinner the layers, and the higher the -temperature, the greater will be the proportion of gas, the greater the -bulk of coke, and the smaller the quantity of tar. - -The coal before it is submitted to the distillatory process, should be -as dry as possible, and the more it is comminuted the better. The very -refuse of the coal called _slack_, provided it is perfectly free from -foreign matter, answers best. It should also be spread in the trays, in -even layers. - -When the retort is in a good working state, the temperature should be -kept up by the application of small quantities of fuel at a time. A -prodigious saving of fuel may be effected by attending the fire -properly, and it is this which distinguishes a careful stoker from a -bungler. For in the working of this retort particularly, it is a -wasteful process to clog up the fire-place with a large quantity of fuel -injudiciously applied. The difference in this respect, with regard to -the economy of fuel is so great, that an expert stoker will work the -retort with one-third less of fuel and half the labour that would be -employed by a negligent workman. - -The quantity of gas produced from a chaldron of coal may be ascertained -by the gas metre, or by the gas holder, if the outlet valve of the -latter be shut during the distillatory process. - -The heat at the same time employed for working the retort, will be best -defined for the stoker’s guide, by copying carefully on paper the red -tint of the retort, as seen through the sight hole, made for that -purpose in the brick-work directly over the fire-place. - -The first six feet of the perpendicular pipe H, fig. 1, plate II., which -conveys the distillatory products from the retort, should be well -cleaned out once a month, the bonnet at the bended part of the pipe H, -fig. 1, is provided for that purpose, as already stated, page 119. - -When the retort remains uncharged, the fire must be kept low in order to -prevent its getting beyond the usual temperature, and the arms and -moveable axis should be turned occasionally, and the door kept close. - -The fire tiles which cover the flues under the retort should be examined -about once a fortnight, and if a tile is melted or broken, it must be -replaced by a new one, because the preservation of the retort greatly -depends upon this precaution. - -All the parts of the arms composing the moveable disc within the retort, -may be taken out of the door of the retort, if they should require a -repair, first taking off the cap from the perpendicular pipe E, fig. 1, -plate II., surrounding the shaft of the retort, then the centre piece, -or rose centre, F, fig. 2, plate II., the shaft D, fig. 2, plate III., -may be drawn up through the pipe which surrounds it. - -When the retort requires cleaning, which should be done once every six -or eight months, a screw may be attached to the upper extremity of the -shaft D, which passes through the retort; by this means, the arms and -rose centre within the retort can easily be raised, to leave the bottom -of the retort quite clear, in order that the lumps of coke, that may be -scattered about, may be easily removed. And if an incrustation of coke -should happen to be attached to the bottom of the retort, it may be -readily detached by a crow bar, or other suitable instrument. - -The trays or coal boxes, fig. 12, plate II., may be made by the stoker, -of sheet iron, (called in commerce No. 16,) framed upon a wooden mould -made for the purpose. - -The temperature best suited for the decomposition of coal by means of -the horizontal rotary retort depends, as has been already stated in the -case of cylindrical cast-iron retorts, altogether on the price of coal, -and the price which can be obtained for the coke. - -In all places where the average price of coal, equal in quality to -(Bewick and Craister’s Walls End) Newcastle coal, or any other species -of coal, capable of producing from fifteen to eighteen thousand feet of -gas from one chaldron, is not less than £ 2. 8s. the chaldron (27 Cwt.) -or upwards, and where coke can be sold at the average price of £. 1 the -chaldron, the horizontal rotary retort should be worked at such a -temperature, that when viewed through the sight hole, it shall appear of -a bright cherry redness, and at which it produces from 15,000 to 16,000 -cubic feet of gas, from a chaldron of coal. - -But in all other places where coal of the same quality to (Bewick and -Craister’s Walls End) Newcastle coal, may be purchased at £. 1 8s. the -chaldron, or at a less price, it will be more advantageous to the -manufacturer, to work the horizontal rotary retort, at a lower -temperature, so as to produce only at the rate of thirteen or fourteen -thousand cubic feet of gas from the chaldron of coal. In the latter case -the manufacturer expends coal in order to save his retort, whereas in -the former case he economizes the fuel, as productive of a gain more -than commensurate for the waste of the retort. - -When the supply of gas required, happens at any time to be less than the -retort when in action is capable of furnishing, the fire must then be -kept low, but the retort should never be suffered to acquire a lower -temperature, than that of a dull red heat visible by day-light. - - - - -PART VIII. - - -_Purifying Apparatus, or Lime Machine._ - -Coal gas, even as obtained from the best species of coal, must be -rendered pure before it is fit for the purpose of illumination. The gas -in its crude state always contains a portion of sulphuretted hydrogen -and carbonic acid; and when burnt, although its illuminating power is -greater in an impure than in a pure state, it produces an oppressive and -suffocating odour, which is speedily perceptible in confined places. The -gaseous product evolved during its combustion, blackens paint and -tarnishes metallic bodies; an impure gas besides strongly acts upon the -copper branch pipes through which it is conveyed. - -To obviate these defects the sulphuretted hydrogen and carbonic acid -which are the cause of them must be removed, and to effect this, no -method more economical and efficacious, has as yet been discovered, than -to bring the gas confined under a pressure equal to a column of water, -not less than eight or ten inches in height, into contact with -quick-lime, diffused through water. Other means have been tried, but all -of them have failed to be sufficiently efficacious or economical on a -large scale. - - -_Lime Machine originally employed for the Purification of Coal Gas._ - -In the lime-machine, until lately in use, the gas was made to pass in -the apparatus, through passages which could not be guarded from being -stopped up in the course of time by the concretion of a quantity of -carbonate and hydro-sulphuret of lime, formed during the purification of -the gas, so that when the stoppage occurred, a prodigious pressure was -produced in the machine, in consequence of which, it was either found -impossible to keep the distillatory apparatus air-tight, or if this was -accomplished, a great part of the gas was forced through the purifying -apparatus, without coming in contact with the lime, by driving the -column of mixture of lime and water before it, and of course without -being rendered fit for use, previous to its passing into the gas -reservoir. This effect was unavoidable without the precaution of -employing a very dilute mixture of quick-lime and water. - -Numerous instances have also occurred where from the increased pressure -which the gas exerted in the lime apparatus, the tar from the hydraulic -main was driven up with a prodigious force through the dip pipe, P, fig. -2, plate IV., into the retort when the retort was opened, where it took -fire to the imminent danger of the whole establishment. - -The apparatus originally employed was composed of a large vessel closed -on all sides to receive the gas; within this was a smaller vessel or -lime trough open at top containing the quick-lime and water; and there -was also a third vessel, or inverted trough into which the gas was -received. - -This inverted trough was open at bottom, and the edge of the open part -was immersed beneath the surface of the mixture of lime and water -contained in the lime-trough, so that the gas which was introduced in -the last-mentioned inverted trough could not escape therefrom, except -rising up through the lime and water. To facilitate this, holes or -openings were made in the inverted trough near the bottom edge thereof, -and beneath the surface of the purifying mixture, so that the bubbles of -gas were obliged to rise up through these openings. From this -construction of the machine the apertures through which the gas had to -pass, were extremely liable to become stopped up, and dangerous -consequences ensued. - -In order to remedy in some measure the evil, a plan was adopted by Mr. -Malam, for making the gas to pass in thin strata underneath a series of -shelves, placed horizontally in the machine so as to expose the gas in -as large a surface as possible to the contact of the lime and water, and -employing the purifying mixture at the same time in a more dilute -state:--this arrangement is as follows. - -Fig. 4; plate V., represents a vertical section of the machine; it is -made of cast-iron plates, rendered air-tight by screws, bolts, and iron -cement. It consists of three separate chambers, _a_, _a_, _a_, destined -to contain the mixture of quick-lime and water. At the under side of -each chamber, is bolted a cylinder, _h_, _h_, _h_, the lower extremity -of which is furnished with a large flanch, extending nearly to within -the whole inner diameter of the machine. - -From the bottom of each of the chambers, _a_, _a_, _a_, proceeds a pipe -curved upwards, and communicating with a circular vessel, C, C, C, which -serve for the purpose of charging the chambers, _a_, _a_, _a_, with the -mixture of quick-lime and water, and regulating the level of the fluid -within the chambers. The curved pipe likewise prevents the escape of the -gas when the contents of the chambers _a_, _a_, _a_, are discharged. - -The vessels, C, C, C, are provided with a waste pipe and stop-cock, as -shown in the sketch, for discharging the contents of one chamber into -the chamber placed below it, and lastly into the reservoir _e_. - -_b_ _b_, are pipes which convey the gas into the chambers, one extremity -of each pipe communicates with the cylinders _h_, _h_, _h_, and the -other with the chamber below it, and the lower pipe communicates with -the valve M, so that by this means a communication is formed from the -lower cylinder _h_, to the middle cylinder _h_, and from the middle to -the uppermost cylinder. K, is the exit pipe which conveys the purified -gas from the uppermost chamber into the reservoir destined to receive -it. Through the centre of the machine passes a wrought-iron shaft, -furnished with agitators or arms, to stir up the mixture of quick-lime -and water. The arms are not immediately connected with the shaft, but -proceed from cast-iron hydraulic cups, of the usual construction, by -this means the escape of the gas is prevented, nor can the fluid pass -from one chamber into another. The axis is put in motion, by wheel-work -as shown in the design _e_, the handle for turning the shaft. - -_g_, is a receiver to collect the condensible products. The contents of -this vessel may be discharged by a hand pump being attached to the upper -extremity of the pipe _f_, after the cap with which it is closed is -removed. - -The operation of this lime machine is obvious. The gas first passes into -the lowermost chamber of the cylinder _h_, where it comes in contact -with the purifying mixture and passes through the fluid to the top of -the same chamber, and thence through the pipe _b_, into the cylinder -above it which communicates with the lower chamber, where it is acted on -again by the lime and water, and bubbles up through the fluid to the top -of the chamber. From this compartment the gas passes into the third -cylinder, where it bubbles up and passes through the lime and water; and -lastly it makes its exit through the pipe K, into the gasholder or -vessel destined to receive it. - -When the mixture of quick-lime and water in the compartments _a_, _a_, -_a_, of the machine, requires to be renewed, it is let off by the -stop-cock at the bottom of the lowermost vessel into the reservoir _e_. -The fluid contained in the upper chamber may be discharged into the -chamber below it, and so on with the chambers below it, care being taken -to close the stop-cock of the lower vessel. The machine may be recharged -at the uppermost chamber with the purifying mixture. Fig. 5, exhibits -the plan of the machine. _b_, _b_, _b_, the tubes connecting the -chambers. B, the flanch of the cylinder _h_. - -This machine has in part remedied the inconveniences stated pages 141, -142, but the increase in the quantity of the purifying materials which -the apparatus requires, is of itself productive of most serious -disadvantages. - -The greater accumulation of waste lime which such a practice occasions, -renders it necessary that capacious reservoirs and sewers should be -constructed to receive and carry off the refuse materials, and where an -outlet by such means cannot be obtained, the carting away the increased -quantities of waste matter adds greatly to the cost of the gas. - -If attempts are made to convey the waste substances into the common -sewers or drains of the neighbourhood, the proprietors of gas works are -exposed to indictments for a nuisance at the suit of the inhabitants, -and when the near proximity of any river or lake induces an attempt to -convey the waste materials thither, the most serious injury may be done -to the water, which becoming impregnated with hydrosulphuret of lime is -rendered unfit not only for domestic but for many manufacturing -purposes. The latter evil indeed is one which operates also in a greater -or lesser degree, even when the fœtid refuse or hydrosulphuret is -discharged into the common sewers, all of which ultimately empty -themselves into some water course, rivulet or lake. I would here beg to -suggest, that considering how rapidly the new mode of procuring light is -extending throughout Britain,[37] and how much the waters of the country -are liable to be contaminated, from discharging into them the noxious -refuse from the process of purifying coal gas, so as to be rendered -proportionably unfit for the various purposes of domestic and -manufacturing economy, it is well deserving the attention of the -legislature, whether such contamination ought not to be guarded against -by prohibiting enactments. - - [37] The Towns of Edinburgh, Glasgow, Liverpool, Bristol, Bath, - Cheltenham, Birmingham, Leeds, Manchester, Exeter, Macclesfield, - Kidderminster, Preston, Waterford, Rochester, Chatham and several - others, have been lighted with gas within these few years. - -It appears to me that it would be a wise exertion of authority, to -insert in every act of Parliament granted for incorporating Gas-light -Companies, a clause prohibiting the proprietors from ever conveying the -waste material, or any other produce from the manufacture of coal gas, -either directly or indirectly into the common sewers, drains or water -courses, or into rivers and lakes adjacent. The salubrity of the water -we use is of as much consequence to us, as any superior excellence or -saving of cost in our light can possibly be, and we ought to take care -that in profiting by an improvement which science and art have -discovered, we do not unnecessarily depreciate one of those primary -blessings we owe to the bounty of nature. - - -_Lime Machine lately adopted._ - -In the improved purifying apparatus[38] lately brought into use, of -which we shall now give an account, a shaft or axis furnished with teeth -or claws, is applied within the interior of the vessel, and made to act -in such a manner as to scrape out the openings or slits through which -the gas has to pass every time the axis is moved round, and by which -regular clearance all chance of stoppage is avoided without any -augmentation of the purifying mixture. - - [38] This machine has been adopted at the gas works at Chester, - Birmingham, Kidderminster, Bristol, and in many other provincial Gas - Establishments. - -The lime trough is also made moveable on a centre or axis, in such a -manner that it may readily be inverted by a lever from the outside, for -the purpose of emptying its contents into the bottom of an exterior -vessel, from which the waste materials may be discharged at pleasure. - -With this machine we are farther enabled to employ the purifying mixture -in a semi-fluid state, and consequently in a much less bulk; and after -having suffered it to remain in the reservoir destined to receive it, -the waste substance speedily acquires such a degree of solidity that it -may be dug out with a spade and carted away in a small compass. The -safety of the apparatus is therefore insured and the construction of -expensive drains and sewers is rendered unnecessary. The following -description will render the construction of the improved apparatus -obvious. - -A, A, fig. 2, plate II., is a rectangular four-sided prism, made of -cast-iron plates, screwed together air-tight with bolts and cement. The -base of the prism terminates in a rectangular four-sided pyramid placed -with its apex downwards. It is surrounded by an iron stage, supported -upon pillars, as shown in the design. - -Within this vessel, which in fact composes only the outer case of the -apparatus, is contained an oblong trough B, fig. 2, plate II., (it is -shown in the design as if broken down), moveable upon an horizontal -axis, fixed to one of its longest sides, so that by means of the wheel -C, or lever communicating with the axis, and applied on the outside of -the machine, the trough B, may be inverted, and its contents discharged -into the exterior case, or lower part A, A, of the machine. The part B, -of the machine is called the lime trough, because it is destined to -contain the quick-lime and water, by means of which the crude coal gas -is purified. Within this trough B, is inverted an oblong rectangular box -D, closed at top and open at bottom, called the air-box, because it -receives the gas to be purified. - -In each of the longest sides of the box D, are perpendicular openings or -slits (as shown in the design) exactly opposite to each other. Through -the whole length of this box D, passes a horizontal axis furnished with -as many teeth or claws as there are upright openings, through each side -of the box. These claws extend a little way through the openings so that -when the axis, which passes through a stuffing box, is made to revolve -by means of the handle X, the ends of the claws pass through the -openings and scrape them out every time the axis is turned. The claws -operate first on the openings of one side of the box and then on those -on the opposite side. They pass quite through and therefore keep them -clear; those parts of the claws which enter into the openings are narrow -in the direction of their motion, and that part of each claw which is -nearest to the centre, is broad and flat, hence they act as paddles or -rowers whilst they are in motion, to stir up the quick-lime and water. - -Fig. 10, plate III., represents a transverse section of this part of the -apparatus. B, B, is the lime trough; D, the air box inverted into the -lime trough; the dotted circle shows the sweep of the claws when the -shaft is put in motion. The darts show the course of the gas. - -Fig. 10, plate VI., represents a plan of the machine. G, shows the -inverted air-trough with its axis, and the claws or teeth fixed upon the -axis. H, is the lime trough. A, the outer case of the machine; R, R, -the axis, to which is affixed the wheel or lever, for inverting the -trough H. L, the axis and handle to give motion to the shaft upon which -the claws are fixed, for stirring up the contents of the lime trough. - -The inverted air-box D, fig. 2, plate II., is supported within the outer -case of the machine A, A, fig. 2, plate II., by cross bars, and the axis -is put in motion by the handle X, on the outside of the machine. It is -rendered air-tight by a stuffing box, and is provided with wheel-work, -as shewn in the design, fig. 2, plate II., to communicate the motion to -the axis. - -The gas is brought into the air box by the pipe N, fig. 3, which -proceeds from the tar vessel, fig. 3, plate II. The gas cannot escape -out of the machine without displacing the column of fluid in the lime -trough, in order to make its way through the openings or upright slits -in the side of the air box D, and thus bubbling up through the mixture -of quick-lime and water, the depth of which is one foot. The -sulphuretted hydrogen and carbonic acid being thus made to combine with -the lime, the carburetted hydrogen is left more or less pure, it is -conveyed into the gas metre, by the pipe V, where it is to be measured, -and from thence by the pipe W, fig. 4, into the gas-holder. - -When the purifying mixture is to be removed, the workman unbolts the -wheel C, fig. 2, and turns it half way round; (if the emptying of the -lime trough requires more power than can conveniently be applied by -means of the wheel, the axis of the trough may be worked with a tooth -and pinion, a small wheel being attached to the axis of the pinion as a -perpetual handle;) this motion inverts the lime trough B, and its -contents become discharged into the outer case forming the inverted -pyramid of the apparatus, whence the waste materials may be conveyed -into the reservoir or pit Q, by drawing open the sliding valve _o_, fig. -2, plate II., or _o_, fig. 3, plate VII., added for that purpose to the -discharging pipe P, fig. 2, plate II., or _p_, fig. 3, plate VII. To -prevent the air entering into the machine when the waste lime is -discharged, the lower extremity of the outlet pipe P, dips into the -basin Q, fig. 2, plate II., which always contains a portion of the waste -fluid and thus seals the extremity of the pipe P. - -One side of the lime-machine is provided with two large lenses, to -admit light into the interior of the apparatus, so that by means of an -eye-glass fixed in a proper place, the workman is enabled to see into -the interior of the apparatus. And when the machine requires to be -cleaned out, the _manhole_ as it is called, is opened for the workmen to -enter into the apparatus to remove any solid incrustation of carbonate -of lime, or hydrosulphuret of lime that may happen to be formed in the -lime trough, or any other part of the apparatus. - -The wheel C, is loaded with a counter-weight, to balance the weight of -the lime trough. To bring the lime trough again into a proper position, -to be re-charged with a fresh portion of the purifying mixture, the -workman turns the wheel C half round, the contrary way to that which -caused the trough to be turned topside-down, and the trough may then be -re-filled with a fresh portion of lime and water from the reservoir R, -fig. 2, plate II., (or R, fig. 3, plate VII.,) containing the mixture -ready prepared. Y, is a pipe to bring water from a cistern into the lime -reservoir R. The prepared lime which is to supply the machine is put -into the vessel R, and a sufficiency of water being mixed with it, the -mixture is stirred up to the consistence of a semi-fluid mass. - -T, shows the pipe furnished with a sliding valve S, for conveying the -purifying mixture of quicklime and water into the lime trough from the -reservoir R, which is furnished with an agitator to stir up its -contents. - -To give motion to the shaft for stirring up the contents of the lime -trough D, the inventor of this machine (Mr. Clegg,) has happily applied -the gas, to act as a power for that purpose. This operation will be -explained hereafter in describing the gas metre. - -The pipe N, which conveys away the purified gas, proceeds from an -hydraulic valve, to cut off the communication between the gas holder and -the lime machine, if occasion should require it, and to prevent the gas -from passing back from the gas holder into the lime machine. - -It consists of a box containing water into which dips a small pipe, by -means of which the gas passes out of the lime machine, and from thence -into the pipe V, communicating with the gas metre. The box is furnished -with a tube curved upwards to discharge the water when it accumulates -above the required height, and to prevent any quantity being thrown out -of the hydraulic valve, by the concussion of the fluid in the lime -trough. - -One cubic foot capacity of the lime trough is sufficient to purify 1000 -cubic feet of gas obtained from Newcastle coal in twenty-four hours. - - -_Test Apparatus, for certifying the purity of coal gas, and the proper -manner of working the Lime Machine._ - -The proper purification of the gas being a matter of essential -importance, as already illustrated page 140, it becomes of great -consequence to have some ready means of ascertaining whether the workman -does his duty in this respect, by keeping the lime trough D, fig. 2, -plate II., properly charged with the requisite quantity of lime and -water necessary for the purification of the gas. - -For this purpose an apparatus has been adapted by Mr. Clegg to the lime -machine, which serves not only to indicate the quantity of fluid -contained in the machine when gas is manufactured, but which also -enables the workmen to appreciate the quantity of quick-lime necessary -for the purification of the gas, and to ascertain its purity. The -apparatus consists of a closed cup C, fig. 23, plate IV., partly filled -with any coloured liquid. Into this cup is cemented, air-tight, a -straight glass tube _a_, about 2¹⁄₂ feet long and a ¹⁄₄ of an inch in -the bore; the lower extremity of the tube nearly touches the bottom of -the cup, and is therefore sealed by the fluid. _d_, _d_, is a small -copper tube, which forms a communication between the air confined above -the surface of the fluid in the guage cup C, and the gas which is -proceeding into the lime-trough. - -The communication may be established at any part of the pipe which -conveys the gas into the lime machine. When the connection is made, the -fluid in the guage cup C, will be driven up into the perpendicular -measuring tube _a_, by the pressure of the gas, to an altitude equal to -a column of liquid contained in the lime-trough. It is essential that -the tube _a_, be at least 2¹⁄₂ feet in height, if the depth of the -lime-trough is one foot, for without this precaution, the fluid will -rise out of the tube in consequence of the oscillation which it suffers. -By this means the overseer of the works will be enabled, by mere -inspection, to know whether the workmen have charged the lime trough -with the mixture of quick-lime and water to the requisite height, which -should never be less than from ten to fifteen inches. Because the -abstraction of the sulphuretted hydrogen and carbonic acid gas, from the -carburetted hydrogen with which it is combined, is greatly facilitated -by pressure, and there is no inconvenience whatever in operating under a -pressure of a column of fluid of even double the height that has been -stated, provided the apparatus is properly constructed. From experiments -made on this subject, I am justified in stating that one half of the -quantity of quick-lime that is required for the purification of coal gas -in the ordinary way, is sufficient, if the column of the liquid opposed -to the gas is raised to twenty inches high, nor is the evolution of the -gas in any degree retarded under such a pressure. - -The curved tube _d d_, which is cemented air-tight into the gauge cup -_c_, has a free communication with the gas in the guage cup _c_. It -serves to enable the workmen to form some notion of the chemical -constitution of the crude gas, before it passes into the lime machine. -For if the stop cock _e_ of the tube be opened, and the descending leg -_a_ of the bended tube _d_ be immersed in a glass containing a solution -of super acetate of lead, some notion may be formed by a little practice -of the quantity of lime requisite for the purification of the gas, from -the quantity of (black precipitate) hydrosulphuret of lead produced. Two -per cent of quick-lime to the coal employed (if Newcastle coal) is -usually sufficient for the complete abstraction of all the sulphuretted -hydrogen and carbonic acid, contained in the crude gas, provided the -operation be carried on under a pressure of not less than a column of -water twelve inches in height. - -The test tube _f_, properly so called, may be adapted to any part of the -pipe which conveys the purified gas to its place of destination. It -serves to ascertain the purity of the gas, after it has been acted on by -quick-lime, by suffering the gas to pass from the tube into a solution -of super acetate of lead, which speedily becomes discoloured, if the -gas contains sulphuretted hydrogen. The presence of carbonic acid is -rendered obvious, by a white precipitate being produced when the gas is -made to pass through barytic water. The precipitate, which is carbonate -of barytes, effervesces with acids. - -It must be obvious that the apparatus which we have now been describing -does not require to be placed in the immediate vicinity of the gas light -machinery. It may be arranged in the counting-house of the overseer, -who, by mere inspection, can then at all times detect the slightest -irregularity or insufficiency in the process thus given to the gas light -manufacture, a degree of scientific controul of which few arts can -boast. - -The following method has been found economical and convenient, for -preserving quick-lime in a ready state, fit for the purification of coal -gas. - -Take the lime as soon as possible after it is burnt; put it into a pit -eight or ten feet long, five or six wide, and five or six deep, -constructed of brick-work and level with the ground. By this pit set a -wooden trough about six feet long, three feet broad, and two feet deep. -The trough should have at one end a hole about six inches square, -covered with an iron grating, the bars of which are a quarter of an -inch distant. Let this grating be provided with a slider, which can -occasionally be drawn up to uncover, or pushed down to cover, the -grating. Put three or four bushels of lime at a time into the trough; -throw water on it, and mix it up into a thick fluid mass with a hoe -perforated with holes. When there is a good quantity of liquid, draw up -the slider and let the slacked lime run into the pit. Throw more water -on the remaining unslacked lime, and lastly reject those pieces which -will not slack. The trough should have a small inclination and project -over the pit. - -After the lime thus slacked has been five or six hours in the pit, it -will take the consistence of a stiff paste, which it retains for years. -It should then be kept covered to keep it clean and to exclude the free -contact of the air. For those who use larger quantities of lime, several -pits should be constructed in preference to one larger reservoir. When -the lime is wanted for use it may be dug out with a spade, and readily -diluted with a sufficient quantity of water. - -The quick-lime thus prepared forms a perfect homogeneous mixture. The -practice of throwing lime simply slackened into the lime cistern is a -wasteful and slovenly process, as will becomes obvious on examining the -waste hydrosulphuret of lime discharged from the machine, which will be -found to abound with lime in a concrete form, unacted on by the -substances with which it was intended to combine. - - - - -PART IX. - - -_Gas Holder._ - -The name of gas holder, or, as it is improperly called, gasometer, is -given to the vessel employed for collecting the gas and storing it up -for use. In the principle and construction of this part of the gas light -machinery, peculiarly valuable improvements have of late been made. They -have contributed to lessen the expence of the apparatus so much, that a -reservoir for storing up any quantity of gas, may now be furnished for -nearly one half the sum which such a vessel cost as originally -constructed. - -In the infancy of the art of lighting with coal gas, the reservoir was -encumbered with a heavy appendage of chains, wheel-work and balance -weights, and from the construction of the machine, it was necessary to -guard it from the impulse of the wind, the action of which on the gas -holder, would have rendered the lights which the machine supplied with -gas, unsteady. - -Hence it was necessary to inclose the gas holder in a building, called -the gasometer house, which formed one of the largest items of -expenditure which the proprietor of a gas light establishment was called -upon to defray. - -Now, however, the whole of these expensive appendages is dispensed with, -nor is the gasometer house to contain the gas holder any longer -necessary, and the machine as now constructed may be fixed in the open -air. - - -_Gas Holder as originally employed._ - -The gas holder, of the original construction, consists of two principal -parts; first, of a cistern or reservoir of water, usually constructed of -masonry, or of cast-iron plates, bolted and screwed together; and -secondly, of an air-tight vessel which is closed at top and open at -bottom, inverted with its open end downwards into the cistern of water. -This vessel is always made of sheet-iron plates rivetted together -air-tight, and was suspended by a chain or chains, passing over wheels, -supported by a frame work. - -If the common air be allowed to escape from the inner vessel, when its -open end is under the edge of the water in the outer cistern, it will -freely descend, and water will occupy the place of the air; but if the -avenue of the escape be stopped, and air be made to pass through the -water, the suspended inverted vessel will rise to make room for the air. -And, again, if the suspended vessel be counterpoised by a weight, so as -to allow it to be a little heavier than the quantity of water which it -displaces, it will descend, if, the entering gas be withdrawn through an -outlet made in the vessel to permit the gas to escape. But if the outlet -be stopped, and air again be admitted under the vessel, it will rise -again. The apparatus, therefore, is not only a reservoir for storing up -the gas introduced into it, but serves to expel the gas which it -contains, when required, into the pipes and mains connected with this -machine. - -According to this construction of the apparatus the interior inverted -vessel forms strictly what is termed the gas holder. It is suspended as -already stated in the outer cistern, by a chain or chains, passing over -pullies, supported by blocks and frame work, and to the chain there is -affixed a counterpoise balance, of such a relative weight, as to allow -the gas holder a slow descent into the water, in order to propel the gas -into the mains or vessel destined to receive it, with a very small and -uniform weight. - -It will be obvious, that when a gas holder of this construction becomes -immersed in the water, it loses as much of its weight as is equal to the -bulk of water which it displaces, and hence to render its descent -uniform, and to preserve the gas within, of an invariable density, at -any degree of immersion, a greater counterpoise is required as the gas -holder rises out of the water. - -Among various methods which have been adopted to attain this object, the -ends of the chains by which the gas holder is suspended, have been -fastened in separate grooves, in the edge of a large wheel or pulley, of -such a diameter, that the gas holder rises to its full height, before -the wheel makes one revolution. - -In another groove in the edge of the same wheel, was fixed the end of -another chain, to which a balance weight was suspended. This weight was -made nearly equal to the weight of the gas holder. To equalize the -density of the gas within the gas holder, at any degree of immersion of -the vessel, the weight chain was made to pass over a wheel, furnished -with a spiral groove, so as to make the radii of the wheel, change -reciprocally with the relative weight of the gas holder, and -consequently to render the pressure of the gas holder constant and -uniform. - -Another and more elegant method of obtaining an uniform elasticity of -the gas within the gas holder, and which has been more generally -adopted, consists in passing the chain or chains by which the gas holder -is suspended over a pully or wheels, and making the weight of that -portion of the chain, which is equal to the depth of the gas holder, or -that part of it which becomes immersed into the water, equal to one -half of the weight of the specific gravity of the gas holder. - -It is obvious that before the purified gas can be admitted into the gas -holder, the vessel must be allowed to descend to the bottom of the -exterior cistern, in order to get rid of the common air which it -contains. This may be effected rapidly by opening the _man hole_ at the -top of the gas holder, to cause the vessel to descend completely into -the outer cistern filled with water. The man hole is then screwed up -again air-tight, and the machine is ready to receive the gas. It is -obvious that the operation of opening the man hole for letting out the -common air, requires only to be done once prior to the commencing of the -working of the apparatus. - - -_Gas Holder with Governor, or Regulating Gauge, lately brought into -use._ - -It must be obvious that the gas holder, of which a description has been -given in the preceding page, requires a machinery at once ponderous and -very delicate, qualities not easily reconciled in the construction of -such a machine. It is necessary that the specific gravity apparatus, or -regulating chain, wheel work and balance weight, should be constructed -so correctly as never to suffer the gas within the vessel, to alter its -elasticity. The machinery requires an expensive framing for its support, -and independently of this, the gas holder must be inclosed in a -building, in order to protect it from the impulse of the wind, the -action of which would render the lights supplied from the apparatus -unsteady, as already stated. The expensive and cumbersome specific -gravity apparatus has been wholly superseded by an ingenious contrivance -called the regulator or governor. The action of this machine, for which -we are indebted to Mr. Clegg, is, that it regulates the density of the -gas prior to its entering into the mains, to any required degree, -whatever its density may be in the gas holder. - -To accomplish this object, the apparatus through which the gas passes -into the mains, is provided with an aperture which is capable of being -enlarged or diminished by a very slight force. To effect this object the -gas is made to enter a small vessel, and then to pass through a -regulating aperture, the capacity of which becomes enlarged or -diminished by the velocity of the gas to a certain standard. If the -pressure of the gas in the gas holder becomes increased, the regulating -aperture through which the gas passes into the mains, becomes -diminished, in such a proportion, that the velocity with which the gas -issues into the mains, remains constant and uniform. And on the other -hand, if the pressure of the gas in the gas holder becomes diminished, -the regulating aperture of the governor becomes enlarged to effect the -intended regulation. - -The following is a concise description of the manner in which this -instrument is constructed. - -_A_, _B_, _C_, _D_, fig. 9, pl. III. is a hollow cylindrical vessel, or -the outer case of the machine. It is made of sheet iron or copper, -japanned within and without, closed at the top and bottom. It is placed -between the gas holder and the mains, into which the gas is to be -conveyed. _a_, _x_, is a pipe which proceeds from the outer vessel and -branches upwards in the centre of the base of the outer vessel A, B, C, -D. It brings the purified gas into the governor. _b_, T, is the outlet -pipe which conveys the gas from the governor into the mains. It is -placed above the inlet pipe and communicates with the interior vessel. -G, H, a short projecting hollow cylinder, which proceeds downwards from -the centre of the base of the outer case of the machine A, B, C, D. _u_, -_x_, _y_, _z_, is the regulator, properly so called; it consists of a -small conical vessel, also made of sheet iron or copper, closed at the -top and open at bottom, japanned within and without. This vessel rises -and falls vertically in the outer cylindrical case. A, B, C, D, of the -machine, when the latter is filled with water. It is kept steady in its -motion by two slender guide rods, as shewn in the sketch. - -Between the inlet pipe which conveys the gas into the governor, and the -outlet pipe which conveys the gas into the mains, is fixed horizontally -a partition plate, having a circular aperture in the centre. This plate -is seen between the letters _x_, T. - -Through this orifice passes a perpendicular axis P, which is fixed at -the top in the centre of the regulator or interior floating vessel _u_, -_x_, _y_, _z_. - -The interior extremity of the axis P, is furnished with a cone, having -its base downwards, and projecting beyond the pipe _a_, _x_, into the -short cylinder G, H. The base of this cone slightly exceeds the diameter -of the orifice _x_, T, so as to close up entirely, when the regulator is -raised to its greatest height in the outer vessel A, B, C, D. But when -the floating vessel _u_, _x_, _y_, _z_, descends in the outer vessel A, -B, C, the vertex of the adjusting cone P, is just entering the aperture. - -The regulator is conical, and its form is in exact proportion to the -loss of the weight of water which it displaces; so that the gas conveyed -into it always retains an invariable density at whatever height the -regulator may be immersed in the water in the outer vessel. If the outer -vessel be filled with water up to the top of the central branch pipe, -the interior vessel will float, and the water will stand in the outer -vessel at the same height as in the inside of the regulator; hence the -density of the gas within will be the same as the outer air. But the -density of the gas in the regulator may be increased at pleasure by -applying a weight to the top of the regulator, the water will then stand -higher on the outside of the regulator than within, and this adjustment -will remain uniform, because the quantity of matter of the regulator is -in the ratio of its specific gravity or loss of weight as it becomes -immersed in the water. - -Let us suppose that the pipe above the partition plate be connected with -a main, and that the outlet pipe below the partition plate be connected -with a gas holder supplying gas into the machine; it will be evident -that if the density of the gas in the inlet pipe becomes by any means -increased, a greater quantity of gas must pass betwixt the sides of the -adjusting cone and the aperture in the partition plate, the consequence -of which will be that the floating regulator will rise, and therefore -contract the area of the partition plate. And if, on the contrary, the -gas in the inlet pipe decreases in density the regulator will descend, -so that whatever density the gas may at any time assume in the gas -holders or mains, its density in the floating vessel _u_, _x_, _y_, _z_, -will remain uniform, and consequently the velocity of the gas passing -into the mains will be regular. - -For when the aperture of the partition plate would admit more gas than -what is necessary for the density of the gas in the mains, the floating -regulator rises, and by that means raises the adjusting cone to diminish -the aperture in the partition plate, and when, on the contrary, the -aperture does not allow a sufficient quantity of gas to come from the -gas holders, the gas passes out of the regulator into the mains, and in -so doing the regulator descends, and consequently the adjusting cone -increases the opening to admit the requisite gas into the mains. - -The further application of this machine, for regulating the height of -the gas flames issuing from burners or lamps of different kinds will be -shewn hereafter. - - -_Gas Holder with Governor or Regulating Guage at the Gas Works Chester._ - -Fig. 7, plate VI., exhibits a perpendicular section of the gas holder at -Chester. A, A, are wooden beams or pillars fixed into sockets or shafts -constructed on the outside of the brick-work, and descending as seen in -the design to the depth of the tank. There are four of these pillars, -three only are seen in the section. B, B, are round iron guide rods -rendered steady by stays at the upper extremity of the rods. - -To the upper and lower edges of the gas holder are fastened eye bolts, -C, C, through which the guide rods, B, B, are inserted, so that the gas -holder must move steadily and firmly. D, E, are the inlet and outlet -pipes which convey the gas into and out of the gas holder. - -F, F, are diagonal stays for supporting the roof of the gas holder, -which has a slope of ten feet from the centre to the circumference. G, -is the wooden curb at the lower margin of the machine. - -This gas holder is circular. It measures forty-eight feet in diameter, -and thirteen feet in height; its weight is eight tons. - -The regulator adapted to this gas holder, measures three feet across its -base, and its height is three feet three inches. The base of the -regulating cone is four inches, and its length two feet. The machine is -made of sheet iron japanned within and without. - - -_Gas Holder with Governor or Regulating Guage at the Birmingham Gas -Works._ - -The construction of this gas holder, as exhibited plate V., fig. 2, -shows a perpendicular section, and fig. 3, a plan of the machine; _a_, -_a_, _a_, _a_, fig. 3, are upright pillars, two of which B, B, are seen -in the section, fig. 2. - -In the centre of the gas holder is fixed a pipe, which allows the gas -holder to slide on the central guide rod G, made fast at the bottom of -the cistern, and at the top of the cross framing. C, C, are diagonal -stays; D, the inlet pipe which conveys the gas into the gas holder E; -the outlet pipe F, the wooden curb. - -The capacity of this gas holder is 30,000 cubic feet; its regulator is -precisely similar to that before described. The weight of the gas -holder, exclusive of the wooden curbs at top and bottom, is between -eight and nine tons.[39] - - [39] The gas holder without specific gravity apparatus, at the Bristol - Gas Works, is constructed on a similar principle. Its capacity is - 43,000 cubic feet. Its regulator is like those already described. - -The gas holder thus disencumbered of its specific gravity apparatus, -requires no building to enclose it, it may be erected in the open air, -for the machine cannot suffer from the rain or snow falling upon it, nor -can the action of the wind render the lights unsteady. - -The saving which has been effected by these improvements is very great. -A gas holder without balance weight and specific gravity apparatus, with -its governor, may be erected complete for action, for little more than -half the cost that would be required for the erection of an apparatus of -the same capacity constructed on the old plan. - -The cheapest house constructed of sheet iron to surround a circular gas -holder of 15,000 cubic feet capacity, supposing the surface of its -cistern or tank to be level with the ground, costs no less than £. 320. -The balance weights and chains £. 60, and the cast-iron framing for -supporting the specific gravity machinery £. 150. - -The cost of a gas holder of the before-mentioned capacity, will be £. -300, and a cast-iron tank for it, £. 800.--If the tank be constructed of -brick-work, it will cost about £. 500, and if of wood (an iron-bound -vat,) it will cost £. 600. - -A governor or regulating guage adapted to a gas holder of from 10,000 to -40,000 cubic feet capacity, costs £. 50. In the construction of the gas -holders, as hitherto described, it is always advisable when the -situation will admit it, that the diameter to the height of the machine -should be in the proportion as three to two. If these dimensions be -observed, and the gas holder is not burdened by iron stays, it will not -displace a column of water more than one inch and a half in height. And -by adapting to the machine, a governor or regulating guage, a -considerable saving will be effected. The gas holder may then be -constructed as shown fig. 7, plate VI., or fig. 2, plate V. A circular -gas holder of 30,000 cubic feet capacity, if properly constructed, -weighs no more than eight or nine tons, including its wooden curb at its -lowest extremity, and its diagonal stays.[40] - - [40] Mr. Lee of Manchester supplies his house, two miles distance from - the manufactory, by means of a portable gas holder.[41] A small - carriage upon springs conveys two square close gas holders made of - wrought iron plates, and each containing fifty cubic feet of perfectly - purified gas, equivalent together to about six pounds of tallow. Each - gas holder weighs about 160 pounds; and has a valve at the bottom, - which is opened by the upright main pipe, the moment the gas holder is - immersed in the pit. The strength of one man is found sufficient for - the labour of removing the gas holder from the carriage to its place. - - [41] Henry’s Experiments on the Gas from Coal, in the Memoirs of the - Manchester Literary and Philosophical Society, 1819. - -The roof of the machine ought to be constructed of thicker sheet iron -than those forming its sides. The only object of the balance weight, is -to counterpoise the weight of the chain of the gas holder of the old -construction, so that when the gas holder is wholly immersed in the -cistern, the chain and balance weight are in equilibrium, deducting the -required pressure with which the gas holder is intended to act. And this -ought never to exceed from half an inch to an inch perpendicular _head_ -of water. - -The sheet iron best adapted for constructing gas holders, is that known -in commerce as No. 16, wire guage.[42] Gas holders made of plates of -iron of this kind, have now been in use for upwards of nine years, and -are not in the least injured or decayed. Self-interested views may -sometimes lead unprincipled workmen to make use of sheet iron plates of -a much greater thickness, but experience has sufficiently shown that any -greater thickness than what has been specified is wholly unnecessary, -and only serves as a drawback to the facility of the general operation. - - [42] A superficial foot weighs three pounds. - - -_Revolving Gas Holder at the Westminster Gas Works._ - -The revolving gas holder is an ingenious contrivance invented by Mr. -Clegg, for storing large quantities of gas. A gas holder of this -construction may be erected with advantage in situations where the -nature of the ground will not admit of a deep cistern either above or -below the ground being constructed, without an enormous expence. - -The base which it occupies is no larger than what would be required for -a gas holder of equal capacity, built on the plan of the gas holders of -which descriptions have been just given. - -It regulates its own specific gravity. And though more expensive in the -construction, yet as it does not require a deep cistern, like the -machines already described, it can be erected at the same cost. The -revolving gas holder is exhibited, fig. 8, plate VI. Its capacity is -15,000 cubic feet; it weighs 12 tons. Plate I., (on the title page,) -exhibits a perpendicular section of the gas holder. - -On inspecting fig. 8, plate VI., it will be seen that this machine is -the segment of a hollow cylinder, or broad wheel, formed by two -concentric cylindric surfaces of 250° each, revolving upon an horizontal -axis, and supported upon a wooden frame or truss, in a brick cistern, I, -K, L. - -The extremity C, D, fig. 8, plate VI., or C, plate I., of the segment of -the cylinder, is open, and the other extremity A, is closed. E, is a -balance pipe, which connects the closed with the open extremity of the -machine. - -This pipe is made of such a weight as to counterpoise the interval -between the open and closed end of the gas holder, so that the machine -may move in a segment of a circle equally, in whatever position it may -happen to be placed, and hence the gas will be discharged from the gas -holder with an uniform velocity. - -The balance pipe E, is closed at the part where the letter E is placed; -H, is a straight pipe, which forms the communication between the -balance pipe E, and the horizontal axis upon which the machine moves. -This axis is hollow: it is supported by stays and braces, as shown in -the design on the title page. The cistern in which the gas holder moves -is 7¹⁄₂ feet deep. It must be evident that the gas being conveyed into -the open end of the hollow axis, it will pass through the pipe H, into -the balance pipe E, and this being stopped up near E, the gas will -proceed into the closed end of the gas holder. The operation will -therefore be as follows: - -Let us suppose the closed extremity of the machine to be at the surface -of the water in the cistern, and the gas flowing through the axis as -described, the extremity of the machine will begin to fill, and -consequently to ascend; the gas holder will therefore continue to move -upon its axis until the open end C, D, fig. 8, plate VI., or C, plate -I., comes nearly to the surface of the water, and when the gas is -required to be discharged, it will return through the same channel by -which it entered. A sufficient pressure is given to this gas holder for -discharging the gas at the velocity required, by means of a weight -suspended to one extremity of a chain, passing over a pulley, whilst -the other end is fastened into the groove of a small circle attached to -the stays of the machine, as shown in the designs. The circle is -graduated to express the capacity of the machine. Thus any degree of -pressure may be given to the gas, and the gas holder will retrograde in -an arc describing 270° of a circle, as the gas becomes discharged, until -the end A, again arrives at the surface of the water. - -The small curved pipe T, plate I., serves to let the common air escape -out of the angular extremity of the machine, whilst filling with gas, -when the margin of this part of the machine becomes immersed in the -water, and to let the common air enter again, when the gas holder is -discharging its contents. - -S, plate I., is a friction sector, upon which the axis of the machine -revolves. The advantage of this contrivance is, that the friction is -very much diminished. The length of the friction sector is eight feet, -the diameter of the gudgeon or axis four inches; therefore the space -described by its outer circumference and its centre is in the proportion -of 96 to 4. - - -_Rule for finding the capacity of a Revolving Gas Holder of given -dimensions._ - -To find the capacity of a revolving gas holder, of given dimensions, -take the area of the whole diameter, then the area of the inner -cylinder, multiply the difference by the length, and from this deduct -one-fourth. - - -_Collapsing Gas Holder._ - -The collapsing gas holder is a still farther improvement by Mr. Clegg, -on this part of the gas light apparatus, and certainly of all the -contrivances which have been invented for collecting and storing up -large quantities of gas, this machine must be pronounced to be by far -the most simple, economical, and efficient. The striking advantage of -the revolving gas holder which we have just been describing is, that it -enables the dimensions of the tank to be very much diminished, where the -nature of the ground will not admit of a cistern of great depth being -sunk, except at an extraordinary expence; but the still superior feature -of the collapsing gas holder which we now come to describe, is, that it -may be constructed of any required capacity, and adapted to a tank or -cistern of such diminished depth, as scarcely to deserve that name. It -requires a sheet of water no more than 18 inches in height, so that it -may be constructed in or upon ground of all descriptions, not only with -every possible facility, but at an immense saving of expence. - -Fig. 1, plate VII., exhibits a perspective view of this gas holder. It -is composed of[43] two quadrangular side plates joined to two end -plates, meeting together at top in a ridge, like the roof of a house. -The side and end plates are united together by air tight hinges, and the -joints are covered with leather, to allow the side plates to fold -together and to open in the manner of a portfolio. The bottom edges of -the gas holder are immersed in a shallow cistern of water, to confine -the gas. By the opening out or closing up of the sides and ends of the -gas holder, its internal capacity is enlarged or diminished, and this -variation of capacity is effected without a deep tank of water to -immerse the whole gas holder in, as required in the ordinary -construction of rising and falling gas holders. The collapsing gas -holder requires therefore only a very shallow trough of water to immerse -the bottom edges of the gas holder to prevent the escape of the gas -introduced into it. The lower edges of the gas holder which dip in water -are made to move in an horizontal plane or nearly so, when they are -opened, so that they dip very little deeper in the water when shut or -folded together, than when opened out. - - [43] From Mr. Clegg’s specification--the same letters of reference - indicate the same parts in all the designs. - -For this purpose the top or ridge joints which unite the two sides of -the gas holder, are slightly raised up when the sides close or approach -together, or slightly depressed when the sides open out or recede from -each other. To guide the whole gas holder in this movement, two -perpendicular rods rise from the bottom of the shallow tank which pass -through sockets in the ridge joints at the upper part of the gas holder. -These sockets are secured by collars of leather round the shafts or -rods, to prevent the escape of the gas, and they are braced by chains -proceeding from their upper extremities and fastened at the ground on -each side of the tank. - -The weight of the gas holder is balanced by levers bent in the form of -the letter L, and placed inside of the gas holder. These levers move on -centre pins fixed at the bottom of the shallow trough, which pass -through the angles of the L levers. The perpendicular arms of the levers -are jointed at their upper extremities to the sides of the gas holder, -nearly in the middle. At the ends of the horizontal arms of the L -levers, are weights to counterbalance the weights of the gas holder, and -both sides of the gasholder are provided with these kind of levers, -which at the same time that they balance its weight cause the ridge -joint of the machine to rise and fall, as before described, so that the -under edges of the gasholder, which are immersed in the water to confine -the gas, must move in an horizontal plane instead of describing an arc -of a circle as they would do if the ridge joint was a fixed centre of -motion. - -When the gas holder is closed the perpendicular arms of the levers stand -nearly in a perpendicular position, but when the gas holder is opened -out the levers become inclined. And as they move upon a fixed fulcrum at -their lower extremities, and are jointed to the sides of the gas holder -at their upper extremities, they allow the whole of the gas holder to -descend gradually upon the guide rods, nearly in the same degree as the -lower edges would rise up if the ridge joint was stable, and if the -sides described an arc of a circle. - -It is obvious, however, that the latter movement is not very essential, -but it is convenient and necessary to make a very inconsiderable depth -of water in the trough or tank serve the purpose it is intended. It may -be also observed that the sides of the collapsing gas holder may be made -to unfold or open on a fixed ridge point as a centre of motion, but it -will then require a considerable depth of water in the tank to keep the -lower edges of the sides and ends of the machine always beneath the -surface of the water, because the sides of the gas holder then describe -an arc of a circle when they are open. Fig. 1, plate VII., is a -perspective view of the apparatus, as it appears when partly filled with -gas. Fig. 2, plate VI., exhibits a perpendicular longitudinal section -made through the middle of the gas holder and tank; fig. 3, plate VI., -represents a transverse section; fig. 4, plate VI., is an end view of -the machine, and fig. 5, exhibits an horizontal plan or section of part -of the gas holder, or one of its ends, to show how the end plates are -jointed together, and the leather applied to prevent the escape of the -gas. - -A, fig. 2, is the inlet pipe which conveys the gas into the machine, it -rises up perpendicularly through the water in the tank, high enough to -prevent the water entering it. B, is the exit pipe for discharging the -gas into the mains from the gas holder. It rises up nearly to the top of -the machine. C, C, are the guide rods, they are firmly fixed at their -lower extremities into a cast-iron framing D, D, beneath the bottom of -the tank. The upper ends of these rods are kept steady by chains E, E, -fig. 3, and fig. 4, descending on each side of the gas holder, and -fastened at bottom to D, D, part of the same iron framing. F, G, K, K, -are the balance (or L) levers which suspend or bear up the gas holders; -they move on fixed centre pins supported in pieces _a_, _a_, fig. 2, and -3, of the framing D. The upper end of the perpendicular arms are jointed -to the iron bars H, H, H, see fig. 2, which are riveted to the side -plates of the gas holder; they are united by knuckle joints W, fig. 6, -which allow the sides of the machine to approach each other till they -come together. The arms _i_, _i_, of the bent levers F, G, K, K, fig. 4, -are placed nearly at right angles to the other arms F, G, fig. 3, and -the extremities of the arms _i_, _i_, are loaded with counterpoise -weights K, K, which always tend to bring the arms F, G, into a vertical -position, and consequently to close up the sides of the gas holder, in -order to expel the gas through the exit pipe B, fig. 2. - -Three pairs of the above mentioned L levers are represented in fig. 2, -in the length of the gas holder to support it in different parts and to -prevent it altering its figure. The weight that must be used is -according to the magnitude of the machine. The pairs of levers F, G, K, -K, fig. 3, are placed side by side on the same centre pins, and cross -each other. K, K, are counterpoises at the ends of the arms _i_, _i_, -they are long pieces of iron extending from one lever K, to the next -lever. The tank is furnished at the bottom with a recess, as seen in -fig. 3, and 4, to allow the arms _i_, _i_, and counterpoises K, K, to -descend beneath the edges of the gas holder. In the course of the -movement of the machine, the sides of the gas holder are shorter at the -top or ridge joints than at the bottom edges, as seen in fig. 2, in -order that the under edges of the folding ends can move in an horizontal -plane. Each of the folding ends is made of two triangular plates, -connected together by an air tight joint, and each plate is again -jointed to its respective side plate, and they are made tight by -introducing a piece of leather or oil-cloth, or any other flexible -substance impervious to air in the angle at the joint. - -Fig. 5, represents the end plates of the gas holder when nearly -extended, but when it is closed up, the two parts N, O, of the end -assume the position as shewn by dotted lines. L, M, fig. 5, shews how -the ends of the two side plates are turned outwards at _b_, to render -them stiff and firm. As all the flexible joints are made strong by -metallic joints or hinges, the leather has no stress to bear but only to -prevent the escape of the gas; R, R, fig. 2, are the collars of leather -to prevent the escape of the gas at the openings in the top or ridge -joint where the guide rods _c_, _c_, pass through. - -The tank must be filled with water to such a level that the under edges -of the sides and ends of the gas holder will be a few inches immersed in -the water. The counterpoises K, K, fig. 3, tend to close the sides of -the machine together, and expel the gas from the gas holder through the -pipe B, fig. 2. The counterpoises are so adjusted in weight as to force -out the gas with the requisite pressure. - -If more gas be introduced by the pipe A, it distends the sides of the -machine and moves them outwards upon the ridge joint. A man hole, as -seen at S, fig. 2, is made in each side of the gas holder, to give -entrance when any repairs are necessary, or to oil or examine the -joining leathers. It is scarcely necessary to add that the form and -dimensions of this gas holder, and the materials of which it can be made -may be varied without any deviation from its essential properties as -they have been now described. For instance, the ends of the gas holder -may be formed of more than two folding plates, united together, if it is -judged necessary, and the levers F, G, may be varied in number, form, or -proportion, provided they balance the weight of the sides and cause the -lower edges of the gas holder to move nearly in an horizontal plane. Or -the balance levers may be laid aside entirely, and the gas holder may be -suspended from the upper part of the guide rods C, C, without moving up -and down thereon. But in this case it will require more water in the -tank to keep the open end of the gas holder always immersed in the -water; the weight of the sides of the gas holder will then tend more to -bring them together and to expel the gas. - -In proportion as the quantity of water sufficient for the tank of the -collapsing gas holder is less than that required for the tanks of other -gas holders, it is attended with this further advantage, that the water -can be let off or removed without any expence when repairs are -necessary. If the repairs indeed are trivial, they can be made without -letting off the water at all, the depth being no more than one foot. In -the case, on the contrary, of the gas holder, with or without specific -gravity apparatus, the quantity of water is so considerable, that the -means provided for carrying it off must always be attended with great -difficulty and expence; and yet it is a provision which is in all cases -indispensable, no matter however difficult or expensive, for no material -repair to the interior of the apparatus can be otherwise effected. - -With regard to the best size of a gas holder adapted to a certain number -of retorts, it may be stated, that this machine should be of a -sufficient capacity to hold the whole quantity of gas that is required -for the supply of the lights during one night, exclusive of what may be -furnished by the retorts during that time. - - -_Rule for finding the capacity of a Collapsing Gas Holder of given -dimensions._ - -The bulk of gas which a collapsing gas holder of given dimensions will -contain, may be found, by multiplying the area of the triangle contained -between the side plates when at their greatest extent, and the surface -of the water, by the mean length of the side plate. For example, suppose -the base of the triangular end plate be 30 feet long, and 30 feet high, -and that the length of the side plate at the top be 40 feet, and at the -bottom 60 feet, - - 30 × 15 = 450 area of end plate, - 450 × 50 = mean length of end plate, - = 22,000 cubic feet capacity.[44] - - [44] A collapsing gas holder of 22,000 cubic feet capacity, costs - about £. 800, it weighs eight tons; a collapsing gas holder containing - 15,000 cubic feet, which weighs seven tons, costs about £. 700, and a - ditto containing 30,000 cubic feet costs about £. 1000. The depth of - the cistern for either is one foot. - - -_Reciprocating Safety Valve._ - -It must be sufficiently obvious that when the gas holder is full, and -the distillation of the gas continues going on, that unless a provision -is made for conveying away the surplus gas, it must escape by bubbling -up from underneath the gas holder. And should the gas holder happen to -be enclosed within walls, the gas may by chance accumulate, so as to -give rise to serious accidents. - -As a remedy for this evil the manufacturers of coal gas have until very -lately contented themselves with what is called a _safety tube_, adapted -to the gas holder, by which, all the superfluous gas was carried away -into the open air; or by leaving large apertures in the roof or upper -part of the building, for the ready escape of the gas. By either of -these devices the danger from the accumulation of waste gas, was in part -only avoided, and instances might be named where dangerous consequences -ensued from an accumulation of gas, in a confined atmosphere, in the -vicinity of the upper part of the gas holder. - -In some instances, indeed, recourse was had to the establishment of a -communication between all the reservoirs and an auxiliary gas holder or -gas holders, by means of a pipe furnished with an hydraulic valve; but -this was an expensive arrangement which required personal -superintendance, and depended, of course, for its efficiency on the -integrity and good conduct of the servant employed. - -Mr. Clegg has now, however, invented what has been termed the -Reciprocating Safety Valve, which has a self-acting operation, and by -which an exit for the surplus gas of any number of gas holders that may -be in action is provided to an unlimited extent. A communication is -established between all the gas holders and a waste pipe, which -communication opens or closes by the action of the gas, as occasion -requires, and which may be extended to any number of gas holders at a -trifling cost. - -The apparatus has now been adopted at the greater number of gas light -establishments, and has been uniformly found most efficient in its -operation. Fig. 9, plate VI., presents a perpendicular section of the -apparatus; _h_, _h_, _h_, _h_, is a small vessel made of sheet iron, -about eighteen inches in diameter, and twenty inches deep, closed at top -and open at bottom. It is inverted into an outer air tight vessel, _i_, -_i_, _i_, _i_, of double the height and rather greater diameter, which -is filled with water to a certain height; D, is a pipe communicating -with the gas holders that are in action; this pipe branches upwards -through the bottom of the outer vessel, _i_, _i_, _i_, _i_, and reaches -a little above the surface of the water in the outer vessel. E, is a -small pipe, the upper extremity of which is sealed by means of an -inverted sheet iron cup G, the edge of which is submersed under the -surface of the water in the outer vessel, _i_, _i_, _i_, _i_. This pipe -conveys the waste gas into the upper part of any chimney. - -For let us suppose that the gas holders become overcharged; the gas must -then acquire an increased density before the wooden curb of the gas -holder G, fig. 7, plate VI.,[45] at the lower extremity of the -overcharged gas holder can begin to rise out of the water. But when the -elasticity of the gas is thus far increasing, and before the curb can -wholly emerge out of the water, the small vessel _h_, _h_, _h_, _h_, of -the reciprocating safety valve, ascends, and consequently establishes a -communication between the overcharged gas holder and the pipe D, of the -reciprocating safety valve. The surplus gas thus passes into the waste -pipe E, E, which had been before sealed by the inverted cup G, and is -hence conveyed into the upper part of the chimney where it terminates, -so that no accumulation of gas can ever take place above, or in the -vicinity of any gas holder. - - [45] Every gas holder ought to have a wooden curb at the bottom. - -It must be obvious on the other hand, that when the gas in any of the -gas holders has recovered its original density, the reciprocating safety -valve will again be closed by the descending of the cup G. - - - - -PART X. - - -_Gas Metre, or Self-acting Guage, which measures and registers, in the -absence of the observer, the quantity of Gas produced in a given time, -from any given quantity of coal, or consumed during a given period, by -any number of burners or lamps._ - -For the invention of this machine we are indebted to the ingenuity and -talents of Mr. Clegg, and undoubtedly, of all the improvements with -which the new art of procuring light has been recently enriched, there -is none which has been attended with results more beneficial to the -interest both of the manufacturer and consumer of coal gas. - -In this machine we see combined a standard or check on the conduct of -the workmen, which enables the manufacturer of coal gas to assure -himself of obtaining at all times the greatest possible produce from his -establishment; a measure by which he can deal the gas out to his -customers in whatever quantities they may require it, and an index which -registers the exact quantities furnished, and thus serves as an -infallible account of debtor and creditor between the seller and -purchaser of gas. - -This machine, therefore, performs at once all the duties of an overseer, -meter, and book-keeper, and performs them all so much more effectually, -that its operation is not dependant on matters so uncertain as the care -or integrity of servants, but on unerring principles which are fixed and -incapable of any hidden misapplication. - -The view in which this machine naturally demands our particular -attention is that in which as a standard of the work which ought to be -performed, it enables the manufacturer to make sure of obtaining the -greatest possible produce from his establishment. - -The gas metre serves this purpose in the first place by enabling the -proprietors of gas works to know what is the utmost possible quantity of -gas which can economically be obtained from any given portion of coal, -with a given portion of fuel, in any given time. - -It is necessary, in every gas light establishment, in order to know -whether as much gas is obtained as might and ought to be produced, that -it be previously ascertained by a series of experiments how much gas the -species of coal used at the works is capable, on an average, of -producing, and such data it is obvious, can only be obtained by means of -an apparatus, which, like this gas metre, shall take measure of the -quantities of gas supplied by the manufactory at all times, and under -all circumstances. - -It may, perhaps, be imagined, that assays sufficient for that purpose -might be made by means of a few retorts, or small experimental -apparatus, or by noting down the quantity of gas produced at the works -during the time the valves which convey the gas into the street mains -are shut, and during which time the capacity of the gas holders may -afford a rule for ascertaining the quantity produced. But nothing can be -further from the truth; assays of this description to be practically -useful and to serve as a basis for the operations of a large -establishment, must be made on a scale of magnitude and be continued for -a considerable period of time as well as under every variety of -circumstances. - -The quantity of gas obtained from any given quantity of coal, varies so -much with the degree of heat applied, and the circumstances under which -the decomposition of the coal is effected, that the solitary product of -any one period of time can afford no positive criterion for the product -of any other period. A correct general conclusion, in short, can only be -drawn from the result of experiments carried on uninterruptedly through -a succession of days and nights, and such a continuity of experiments -could, previous to the invention of the gas metre, only be affected by -means of two separate gas holders, one for measuring the gas as it is -produced, and the other for receiving the gas after it is thus measured, -in order to its being transferred into the mains. By the aid of a single -gas holder, an admeasurement could obviously be effected only during the -time the valves which transmit the gas into the street mains are shut, -and this, when the days are short, as in the winter season, the most -productive period of the whole year, is only about eight hours out of -the twenty-four, leaving nearly two-thirds of each day, during which, no -account could be taken of the quantity of gas produced at the works. - -It deserves further to be observed, that when two gas holders are -employed, the utmost that can be effected by them, is the admeasurement -of the gas produced, while the distinguishing feature of the metre is, -that it not only measures, but by its own action registers the quantity -of gas produced, or expended, in any given time. - -Nor does the whole merit of this machine, in an economical point of -view, consist in its thus furnishing the manufacturer with an infallible -criterion of the quantity of gas which ought at all times to be -produced; for, in the second place, it enables him by the several -experiments which have supplied that criterion, to ascertain at what -least possible expenditure of fuel, and in what space of time the -greatest possible quantity of gas can be produced. - -The advantage of the gas metre, in these additional respects, will be -sufficiently demonstrated by attending for a moment to the situation of -the manufacturer of coal gas, when without any such protecting register. -Suppose, for example, that the manufacturer desires to know whether his -workmen have made during a given time, (say during the night), the -quantity of gas which they ought to have produced from a given quantity -of coal, or whether they have consumed no greater proportion of fuel for -its production than was absolutely necessary. He may, upon examination, -find all the retorts in an excellent working state, but whether they -have been so during the whole of the night, or whether the requisite -quantity of gas has been really produced during the time that the valves -which convey the gas into the mains have been open, is to him a matter -of uncertainty. The workman may, as has been too often the case, have -neglected the fire during the night, and on every such occasion, in -order to bring back again the retorts to a proper working state, as well -as to redeem the time lost, he may have urged the heat to a degree of -intensity much exceeding the temperature best suited for the most -economical production of the gas. And however injurious such irregular -modes of operating may be for the master’s interest they are altogether -shrouded from his observation. It deserves also to be noticed that the -loss occasioned by this irregularity of operating is not merely a loss -of fuel, for in consequence of it the retorts, (particularly if -cast-iron retorts of the usual forms,) are liable to more injury in one -day than they would be during a whole week, if properly attended. - -When the proprietor of the establishment, on the contrary, has recourse -to the gas metre, not one of all these evils can occur without being -liable to certain and instant detection. From the data which preceding -experiments on the productiveness of the species of coal used at the -establishment have furnished, the overseer of the works is always -enabled to determine, from the portion of coal he finds used, how much -gas ought to have been manufactured during any space of time that has -elapsed, and also the portion of carbonizing fuel which was necessary -for the production of that quantity of gas; and comparing these data -with the quantity of gas which the index of the gas metre announces has -been produced, he is enabled to determine by mere inspection, in an -unerring manner, whether the workman has acted with that sedulous -attention to his duty which the economy of the establishment demands. - -The many important advantages in short which the manufacturer of coal -gas derives from this machine, considered _as a standard or check on the -conduct of the workmen_, may be summed up in this--that while, without -the aid of the gas metre, no establishment can be possibly more exposed -to suffer from the ignorance of managers or the want of fidelity in -servants, than a gas manufactory, there is none which is more -independent of either than a gas manufactory, possessed of this -important apparatus. Nor can the amount of that possible loss be -regarded as otherwise than extremely serious, when attention is paid to -the difference in profit and loss between conducting the process of -manufacturing coal gas on a system founded on the deductions of -experience, and an assiduous attention to keeping up a regularly -sustained temperature; and conducting the process on a system of random -calculation and irregular working,--a difference, which as appears from -the details already laid before the reader, amounts in respect to the -quantity of gas produced, to from fifty to one hundred per cent.; in -respect to the waste of machinery, to upwards of eighty per cent.; and -in respect to the consumption of fuel and time to a sum in the ratio of -the loss experienced under both these other heads. - -The Second General Point of View in which the gas metre claims our -attention, is, its excellence as a standard of fair dealing between the -seller and consumer of gas, by enabling the former to supply the gas in -whatever quantities it may be required, and serving, at the same time, -as a self-acting register of the quantities furnished. It is for this -purpose merely necessary to connect the gas metre with the pipe of -supply, which conveys the gas to any burner, or number of burners, or -lamps, and the index of the instrument will regularly announce the -precise quantity of gas which has passed through the machine during any -period of time, from one day to a number of years, without requiring any -particular sort of care whatever. Every person must have noticed how -shamefully many individuals disregard the terms on which they have -contracted for a supply of gas, some by means of the excessive flame -they keep up, and others suffering the lights to burn hours beyond the -time stipulated and contracted with the gas light company which supplies -them. The latter have officers, it is true, whose duty it is to check -such abuses as far as is in their power, but having no right of access -to the premises of individuals, their vigilance can only extend to shops -and places open to public view and of general access; and to these, of -course, but occasionally. In short in every place where gas is supplied -on contracts to pay for burning it a limited time, by means of certain -sized burners or lamps, instead of according to the quantity actually -furnished, the seller must always be in a greater or less degree, and in -some cases wholly dependent on the care and honesty of the purchaser for -the protection of his commodity from waste and depredation. But when on -the contrary the seller possesses, as he now does, by means of the gas -metre, an infallible check of the exact quantity of gas consumed in a -certain time, and the purchaser is bound to pay for as much as he uses, -the former is relieved from every apprehension or chance of being -defrauded, and the latter is furnished with the same motives for -economizing gas as he would have for economizing oil and candles. - -The manufacturer is certain of obtaining what he has a just right to, -value for the whole quantity of gas supplied, and the consumer is -assured that if he wastes the gas unnecessarily, he must as he ought, -pay the price of his own carelessness or profusion. Equal justice is -done both to the consumer and seller, and the public at large are at the -same time most materially benefited, in as much as they are saved from -paying for the expence of that waste of gas by a few, which from the -former impossibility of tracing it to the offending parties, was -necessarily added to the whole cost of the gas, and equally partitioned -upon all the individuals who made use of it. The waste being now -transferred to those who occasioning the waste and ought alone in -justice to bear it, the price of the gas to the equitable and honest -consumer, is thus reduced to an equitable and correct measure of value. - -The benefits of this invention have a yet wider range; not only does it -secure full value for the whole of the gas manufactured, but it tends to -make the gas a greatly more marketable article. For in the system of -charging for the supply of gas by the year, half year, or quarter, and -at one common rate, many individuals who are only occasionally in want -of gas lights, or whose demand is irregular and uncertain, such as the -proprietors of public rooms, theatres, &c. are debarred of availing -themselves of this kind of illumination, except at an expence quite -disproportioned to what other more regular customers pay, and out of all -proportion of the value of the quantity of gas consumed by them. The gas -light under such circumstances is not as it ought to be, a light for -all. It is not as oil and candle are, a benefit which every one may -obtain who is in need of it, and in such quantities as may best suit his -means and convenience. One of the capital advantages, of the gas metre, -however, is, that it makes gas a substitute for oil and candles, -applicable under all circumstances, and that it enables the manufacturer -without the least prejudice or chance of prejudice to his interest, to -supply gas in whatever quantities it may be demanded, and at a fair -proportioned price. - -In speaking thus of the influence which the gas metre must have in -attending the beneficial application of the new lights, we are not -unaware that situations may present itself where the action of the metre -might be impeded from the want of a sufficient pressure of the gas in -the pipe of supply connected with it. But this can never be the case -except where the pressure of the gas in the pipe of supply is so low as -three-eighths of an inch of a column of water, and in all such cases it -is only necessary to give a greater capacity to the wheel of the -machine, than would be necessary under other circumstances, and this -will at once make up for the inferiority of pressure. In point of fact, -therefore, no situation can occur, where the application of the machine -may not be rendered available.[46] - - [46] See directions to workmen, for adapting gas metres, p. 229. - -Nor do the various advantages which have now been detailed, form all the -good that this important machine is capable of furnishing. The gas metre -furnishes at its axis a power which has been ingeniously applied to put -in motion the shaft of the lime machine, employed for purifying the gas, -see fig. 3, plate VII.[47] The importance of a power thus certain in its -operation, and obtained free of expence, must at once be obvious, when -it is considered that upon whatever plan the purifying apparatus or lime -machine may be constructed, it is absolutely essential, that its -contents be kept constantly in motion, in order to produce the desired -effect upon the crude gas, which would otherwise pass away in an impure -state. - - [47] The upper axis communicates with the agitating shaft of the lime - machine, and the lower axis is a continuation of the shaft of the gas - metre. The two pullies are connected by a strap. - -When the charge of keeping the agitating shaft of the lime machine in -action, is intrusted to a workman, there is no positive security against -his occasionally neglecting his duty, whereas by applying the gas metre -to that purpose, the manufacturer is assured beyond the possibility of -deception, that when gas is produced, that gas is as certainly purified, -and a saving is effected in point of labour of the expence of two men, -one during the day, and one during the night. - - -_Description of the Gas Metre at the Royal Mint Gas Works._ - -Fig. 4, plate II., represents a perpendicular section of the gas metre. -It is placed between the purifying apparatus or lime machine, and the -gas holder fig. 8, plate III., exhibits a front elevation; fig. 1, plate -III., a perspective view, and fig. 6, plate III., a transverse section -of the machine. - -It consists of a hollow wheel or cylinder, made of thin iron plate, -revolving upon an horizontal axis, in the manner of a grindstone; this -wheel is enclosed in a cast iron air tight case containing water. - -The cylinder or wheel, is composed of two circular channels, 1 and 2, -fig. 4, plate II., concentric to each other. The larger or outer channel -1, is divided into three equal compartments, by partition plates, marked -_a_, as shewn in the design. The compartments are provided with -hydraulic ducts or valves, made at the upper part of every partition -plate _a_, _a_, _a_, and by means of them a communication is formed -between the larger concentric channel 1, and the outer case in which the -wheel revolves. - -Similar valves are also placed at the foot of each partition plate, they -are seen near the letters _a_, _a_, _a_, and by this means, a -communication is established, between each compartment or chamber of the -larger concentric channel 1, and the smaller interior circle 2, of the -wheel. - -On inspecting the design, it will be seen that the valves are situated -in opposite directions to each other, hence there can be no -communication either between the inner smaller concentric channel 2, and -the larger compartment of the wheel 1, nor between the latter -compartment, and the exterior case, in which the wheel revolves, except, -through the valves _a_, _a_, _a_, which form the communicating ducts. It -will be seen also, that these valves are carried from one chamber of the -machine into another, but in opposite directions; the entry into one -chamber, being in the opposite direction to the hydraulic duct, placed -in the other chamber. - -From these particulars the action of the machine will be obvious. - -Let us suppose that the outer case (which is marked in the sketch by a -black tint,) in which the wheel revolves, be filled with water, to about -an inch above the axis of the wheel, and that gas is conveyed into the -interior small channel, by a pipe, passing along the axis, so as to -allow the wheel to turn freely round, and that the pipe is turned up at -right angles in the inner chamber, and projects a little way above the -surface of the water, as shewn in the design. The gas then must enter -into the interior chamber of the wheel above the surface of the water, -and must press against the adjacent partition; it will therefore cause -the wheel to turn round, and in consequence of this motion, the next -partition plate will press the gas against the surface of the water, and -cause it to pass through the hydraulic opening, in an equal quantity to -that, which is introduced into the exterior chamber. - -This alternate filling, and discharging, of the contents of each -chamber, will take place once during every revolution of the wheel, and -hence the number of times each particular chamber has been filled, and -emptied of gas, may be known. - -In fact this machine performs the office of three revolving gas holders, -fixed on an horizontal axis, and moving in a cistern, which is the outer -case of the machine. One gas holder, or one compartment of the machine, -is always in the act of becoming filled with gas, another is emptying -its contents into the outer case, from which it passes into the -reservoir, where it is to be stored up, or to the lamps, where it is to -be burned, and the third compartment is stationary, or in an -equilibrium. The wheel in any situation will therefore always have one -of its receiving, and one of its discharging valves open, and -consequently it will revolve. - -Now to ascertain the quantity of gas discharged by one revolution of the -wheel, we need only to know the capacity of the chambers, and add them -together. Let us for example suppose, that each chamber contains 576 -cubic inches, then one revolution of the wheel, discharges a cubic foot -of gas. To register the total number of revolutions which the wheel -makes in a certain time, a train of wheel-work is connected with the -axis of the metre, see fig. 8, plate III.; it consists of a pinion -impelling a common train of wheel-work, composed of any number of -wheels. The pinion on the axis of one wheel, acts into the circumference -of the next wheel, and the circumference of the wheel being as ten to -one, it is obvious whilst the metre makes 100,000 revolutions, if the -series consists of six wheels, the last wheel of the series, will only -have made one revolution. Each axis of the wheels is provided with a -finger and dial plate, divided into ten parts, therefore any number of -revolutions may be read off at any time by inspection betwixt 10,000,000 -and one. - -The velocity with which the metre acts, is of course in proportion to -the quantity of gas passing through it. Thus suppose there is a burner -or gas lamp connected with the machine, of one foot capacity lighted, -which consumes four cubic feet of gas in an hour, the gas metre performs -four revolutions per hour, and so on for every number of burners or -lamps, not exceeding the number which the machine is calculated to -supply. - -To render the construction of the gas metre more obvious, we have at -fig. 6, plate III., exhibited a transverse section of the machine; _a_, -is the outer case of the machine in which the wheel revolves. B, B, the -outer or larger concentric chamber, (marked 1, in fig. 4, plate II.) L, -the inner or smaller concentric chamber, (marked 2, in fig. 4, plate -II.) _d_, the index on the axis which passes through a stuffing box in -front of the machine. 5, 5, 5, 5, are stays or braces for supporting the -wheel; they are likewise seen in fig. 4, plate II. A, is the inlet pipe -for the gas to enter into the machine. The gas passes through the pipe -_h_, and from thence into the curved pipe _i_, into the interior chamber -L, of the metre. The pipe _h_, is surrounded by a second pipe K, which -has a small aperture at _x_, the office of which is, to act as a siphon, -in order to preserve the proper level of the water in the machine. The -water is poured into the machine, through the small funnel at the back -of the entrance pipe A. _y_, is a float, which stops the performance of -the metre altogether, if a fraudulent attempt should be made, to stop -the registering of the metre, by drawing off the water with which it is -charged. In fig. 1, plate III., _a_, is the inlet pipe; _b_, the outlet -pipe of the gas; and fig. 2, shows the interior chamber. - -The registering wheel work, may be adapted to any part of the machine, -and the motion may be communicated by a mitre wheel, from the shaft of -the machine to the index. - -The gas metre at the Royal Mint measures and registers 30,000 cubic feet -of gas every twenty-four hours.[48] - - [48] The gas metre at the Bristol gas works registers 60,000 cubic - feet of gas every twenty-four hours. The metre at the Chester gas - works registers 40,000 cubic feet every twenty-four hours.--One of the - metres at the Birmingham gas works registers 40,000 cubic feet, and - the other (now erecting) will register 100,000 cubic feet every - twenty-four hours. - - -_Rule for calculating the weight, which a Gas Metre of given dimensions, -will raise to a given height, in a given time._ - -The following calculation will exemplify the power produced by a gas -metre constructed to register 60,000 cubic feet of gas, in a day. The -diameter of such a metre would be six feet, its depth three feet, and -the depth of its rim eighteen inches. - -The section of the rim would therefore contain 648 square inches, and -supposing the pressure of the gas passing into the machine to be equal -to a column of water two inches high, its buoyant power would then be -equal to 1296 cubic inches of water, or forty pounds and a half weight. -The mean diameter of the metre is 4 feet 6 inches, which multiplied by -three, gives the perpendicular height that forty pounds and a half -weight, would be raised by each revolution of the metre. The number of -revolutions, in one hour which the metre makes, is 40, they would raise -forty pounds and a half, 540 feet high in one hour. - -Such a power is more therefore than sufficient to keep in motion the -shaft of the lime machine. - - -_Gas Holder Valve,--Siphon, or Water Reservoir._ - -This name is given to the principal hydraulic valve, by means of which a -communication is established between the gas holder or gas holders, and -the principal pipe, leading to the mains. - -Fig. 7, plate III., exhibits a section of this valve. It is composed of -an air tight box, A, A, A, A, containing a portion of tar, or water; -_d_, is the inlet pipe which communicates with the gas holder, B the -outlet pipe; which conveys the gas into the mains. C, C, is an inverted -cup, furnished with a sliding rod, passing through a stuffing box, so -that by means of the rod, the cup may be raised or depressed. For it is -obvious that a communication will be established between the inlet pipe -_d_, and the outlet _B_, when the cup is raised above the surface of the -tar or water in the box A; and that the communication will be cut off -when the cup is depressed into the tar. In the latter position the cup -is shewn in the design. The sliding rod which raises and depresses the -cup, passes through a frame E, E, affixed to the upper part of the box -A, and which serves as a guard for the rod, so that it may be locked by -means of a cutter passing through the sliding rod, and the frame of the -box. - -Fig. 3, plate III., exhibits a similar valve, which at the same time may -be used as a _water reservoir_, commonly called a _siphon_, for -collecting the water that may happen to accumulate in the mains, a -provision which it is essential should be made at the lowest place, -where two or more pipes incline towards each other. For it is obvious, -that if a fluid should happen to accumulate in the angular part, where -two descending pipes meet, to a height sufficient to fill the angular -point, the communication between the two pipes would be completely cut -off, so that the gas could not pass. _x_, _x_, _x_, _x_, fig. 3, is the -reservoir; A, the inlet pipe; B, the outlet pipe; _b_, a short cylinder -communicating with the exit pipe B, it is open at bottom and closed at -top. D, _d_, the hydraulic cup which, when raised by means of the -spindle _e_, closes the exit pipe B, by the open end of the cylinder -_b_, becoming immersed in the tar or water contained in the cup D, _d_. -The darts show the course of the gas when the valve is open: _f_ is a -small pipe furnished at top with a screw and covered with a cap; by -attaching a hand pump to this pipe, the superfluous portion of fluid -that may have accumulated in the reservoir, may be removed. _c_, _c_, is -the _equilibrium_ pipe, it connects the exit pipe B with the inlet pipe -A, when the stop-cock with which it is furnished is opened. This pipe -prevents the tar or water from being blown out of the hydraulic valves -that may be interposed between the different descending mains of a -district, as would otherwise happen, in consequence of the sudden -concussion that takes place when the main or gas holder valves are -opened. Because the gas in the mains, and the gas in the gas holders, -are not in equilibrium. But by means of the small pipe _c_, _c_, the -equilibrium is obtained when the stop-cock of the pipe _c_, _c_, is -opened, and this should always be done before the main or gas holder -valves are opened. For by neglecting this condition, the water or tar is -liable to be blown out of all the hydraulic valves, that may happen to -be interposed in the system of the pipes for conveying the gas, and -communications are thus opened, which were intended to be shut. - - - - -PART XI. - - -_Governor or Regulating Guage._ - -The governor or regulating guage, the construction of which has already -been detailed, page 171, we shall here consider as an instrument by -means of which the gas flames of lamps and burners are kept of one -steady and uniform magnitude. - -The velocity of the gas in the mains and pipes of supply, is in the -first instance as various as there are differences in the altitude and -extent of the mains and pipes of supply. A main, at one place will -furnish with a certain pressure of gas, a flame one inch high, while at -a different altitude it will furnish a flame double that height. - -If again the direction of the pipe has many turns or angles, and -contractions, the velocity of the gas will be different on that account, -than if it were direct and uniform. And if the pipe is of any great -length, and of an uniform bore, but unequally furnished with veins or -branch pipes at certain parts, the burners will be very unequally -supplied with gas, those which are near its head will be supplied with a -fuller stream of gas, than those which are situated towards its -termination. - -And independent of these differences thus arising from diversity of -local positions, there will always be one grand variety in the velocity -of the gas, occasioned by the variety of periods during which lights are -required by different individuals supplied from the same main or system -of pipes, as for example: when a certain number of burners are to be -supplied, and it happens that one half of these burners are shut sooner -than the rest, then in consequence of this, the velocity of the gas in -the mains will be materially altered. - -The inequality thus occasioned, may be seen particularly exemplified in -the case of houses situated in the vicinity of any large establishment, -such as either of the great theatres of the metropolis, and supplied -with gas from the same mains. While the theatres are open, the lights in -the adjacent houses are low and feeble, often too much so for the -necessary purposes of the consumer, but the moment the theatres are -shut, the great quantity of gas which they previously carried off, being -transferred to such of the private houses as continue to be lighted, the -gas flames at the latter are raised to an extravagant height, and burn -with an intensity which makes the gas light partake more of the -character of a nuisance than of a benefit. - -It may be necessary for the better appreciation of the extent of this -nuisance to observe, that it does not arise merely from the excess of -light produced, but from the imperfect combustion of the gas, and hence -a disagreeable odour is produced. When the flame is suffered to rise -beyond the standard height, the combustion of the gas becomes imperfect, -part of the gas passes through the flame unburnt, and occasions the -source of the offensive odour alluded to, which the gas lights never -produce when the combustion of the gas is complete. The remedy for all -these inconveniences thus resulting from the various degrees of -velocity of the gas in the mains, is to be found in the instrument now -under description. - -The effect of this machine, as already mentioned, is, that it causes the -gas to issue from the aperture of the burners or lamps with one uniform -velocity, whatever may be the variations which take place in the -pressure which urges the gas to pass through the pipes of supply. And -such is the efficiency of the operation of the machine, that it -regulates the flow of the gas through any burner, tube, or opening, with -a greater degree of exactness, than the centrifugal apparatus, regulates -the action of the steam engine. - -The construction of the regulator to effect this purpose is precisely -similar to the apparatus already described, page 171. When applied for -regulating the magnitude of the gas flames, it is of course usually made -much smaller, of iron plates, japanned within and without. Fig. 4, plate -III., exhibits a perspective view of the machine; _a_, is the inlet -pipe, _b_, the outlet pipe; P, is the regulating cone, passing through -the regulating aperture _x_, T. The floating vessel _u_, _x_, _y_, _z_, -receives the gas introduced into the machine; A, B, C, D, is the outer -air tight case of the regulator. - - -_Directions to Workmen for fixing the Governor and Gas Metre._[49] - - [49] Copied from Messrs. Clegg’s and Crossley’s printed directions to - workmen, for fixing governors and gas metres. - -The governor must be fixed perpendicularly, so as to admit its floating -vessel _u_, _x_, _y_, _z_. Fig. 4, plate III., or fig. 9, plate III., to -be taken out of the outer case of the machine if occasion should require -it. - -The gas enters into the machine from the street mains at the lowest -branch _a_, and passes out of the machine by its highest branch _b_. - -In connecting the pipes of supply, particular care must be taken that -the work is not _bound_, or the governor by any means rendered leaky. It -must be filled with water to the top of the central tube. - -Examine the workmanship of the machine to see that it is perfect, and -that the regulating cone P, is firmly secured to the top of the -floating vessel and well centered. The floating vessels _u_, _x_, _y_, -_z_, should clear the sides of the outer case of the apparatus by a -quarter of an inch; and when sunk down, it should rest even upon the top -of the central pipe, which conducts the gas into, and out of, the -machine. The aperture in which the cone moves will then be at its widest -opening, and when the floating vessel _u_, _x_, _y_, _z_, has risen to -its highest elevation, the regulating aperture _x_, T, will be closed. - -In this situation particular attention must be paid, that the regulating -cone does not stick or rub in any part, but that it descends freely. - -To the lower extremity of the floating vessel _u_, _x_, _y_, _z_, may be -adapted an air vessel for the purpose of reducing the pressure of the -gas. - -The governor must be so fixed, that the water which may condense in the -pipes leading to the burners shall drain back to the street mains, in -order that it may not accumulate in the machine so as to impede its -operations; for this purpose the gas pipes should have a fall of half an -inch in three or four feet. - -When the locality of situation will not admit of the water that may -accumulate in the pipes falling back to the mains, its accumulation -within the governor above the proper level of the water is prevented by -an inverted siphon affixed to the machine, which allows the water to -drain off without any escape of the gas. - -The governor must be firmly fixed to the nearest beam or wall, as the -least vibration will render the lights connected with it unsteady. - -When a situation cannot be obtained sufficiently warm to prevent the -water from freezing, the machine must then be wrapped round with woollen -cloth, or any other bad conductor of heat. The cellar where the gas -enters the house, has generally been found the most convenient -situation. - -For supplying any deficiency of water which the governor may require; a -small funnel with a curved tube is placed for this purpose at the top of -the governor. When the governor is filled to its proper height, the -water will begin to run out of the siphon. - -The mode of regulating the height of the flames will be stated -presently. - -Fig. 11, plate III., exhibits a portable governor or regulating guage, -combined with a gas metre in one case. A, is the inlet pipe which -conveys the gas into the machine, and B, is the pipe leading from the -governor to the lamps or burners. D, a label expressing the quantity of -gas discharged by one revolution of the wheel, and the number of lights -which the metre is capable of supplying when the pressure of the gas in -the inlet pipe is of a density sufficient to support a column of water -of half an inch in height. - -In those situations where the pressure of the gas is equal in density to -support only a column of water one-quarter of an inch in height, a metre -of a larger capacity must be adopted for supplying the same number of -lights; and if the pressure of the gas be equal only to support a column -of water one-eighth of an inch in height, the capacity of the metre must -be still larger, and thus the capacity may be increased so as to equal -every pressure that may occur. The index which registers the number of -revolutions, and consequently the quantity of gas which passes through -the metre, is shut up in the projecting case, near H, furnished with a -lock and key. - -Previously to the gas metre being filled with water, ascertain that the -regulating cone is screwed perfectly air tight into the top of the -floating vessel which receives the gas, and that the regulating aperture -in which the cone moves, together with its spindle and guide rods, work -perfectly free and without friction. Raise the floating vessel to its -highest elevation, thereby closing the regulating aperture suddenly with -the cone; in this situation it must not rub when turned and tried on -every side, but descend with the least friction. - -The gas metre and regulator being thus examined and fixed, the machine -may be supplied with the requisite quantity of water in the following -manner: - -Open the stop-cock which admits the gas into the machine; open also the -aperture E, which serves to show the pressure of the gas in the machine, -and likewise the opening G, which lets out the air whilst water is -poured in at the aperture H. The superfluous quantity of water will run -out by the siphon tube at K. - -Pour water also into the governor until it runs out at the aperture at -M; and when this has been accomplished, till the gas metre with water -at the opening H, until it overflows at the aperture K, when the surface -of the water will appear at the cypher line on the scale board. The -apertures F, G, H, K, and M, may then be closed, and the machine is -ready for action. - -Near to N, is an aperture communicating with the stuffing box in which -the axis of the machine moves, and through which it should occasionally -be supplied with a small portion of melted tallow. - -To adjust the height of the gas flames of the burners, so that they be -all uniform, open the stop-cock which admits the gas into the metre, and -open also the stop-cocks of the burners, and as soon as the air has -become discharged by means of one or two revolutions of the metre, light -all the burners. Adjust the height of the flames in the first instance -by their stop-cocks, that they become all of an equal height, which -should be about double the diameter of the flame; if any of the flames -be too low when the stop-cock is fully open, a small weight must be -placed upon the top of the floating vessel of the regulator, sufficient -to produce the required flame at the burner, and then again adjust the -remaining lights by their stop-cocks as before stated; this being done, -the aperture to which each burner is screwed must be sufficiently -narrowed, that it will admit no more gas than is requisite for the -required height of the flame, when the stop-cock is fully open. The -diminution of the aperture of the stop-cock may be effected by a brass -plug fitted into it, with a hole in its centre, which must be gradually -widened with a drill until the flame has required the proper height. It -is recommended, instead of adding weight to the floating vessel of the -regulator, that the tubes which supply the gas be sufficiently capacious -to render the weight unnecessary. - -The burners should also be examined from time to time. Observe that the -plugs, sockets, and every other part of the gas metre and regulator be -air tight, and that there be no escape of water or gas. - -An escape of gas, either from the metre or from any of the tubes or -burners, will be discovered by looking at the index of the metre, as the -wheel cannot fail to move whenever there is an escape of gas, if the -stop-cock is open which supplies the gas to the metre. The place where -the gas escapes will be found in the usual way, either by the odour -which the gas produces, or by passing a lighted taper over the apertures -and connections of the metre, and along the tubes leading to the -burners, which will cause the gas to take fire at the place where the -leak happens to be. - -The following remarks will assist the workmen in correcting any -irregularities which may occur in the lights connected with the -apparatus. - -A diminution, or extinction of the lights, may be occasioned by a -deficiency of water in the gas metre or regulator; when this occurs the -necessary quantity of water must be supplied as before directed up to -the cypher line on the scale board E, of the metre, and opening the -aperture M, where it may be seen when the water has risen to the proper -height in the governor. - -A diminution of light may also be occasioned by some obstruction or -contraction of the tubes which supply the gas, or by a diminution of the -pressure of the gas in the mains, to which the metre was originally -adjusted. - -When the lights increase above their standard height, and are variable -with the changes in the pressure or velocity of the gas in the mains or -tubes of supply within the house or place, lighted, there is then reason -to believe that the governor is not performing, which may arise from the -following causes. Its floating vessel _u_, _x_, _y_, _z_, may have -become fast by the friction of the spindle or guide rod, requiring -cleaning, or by an accumulation of water in the air-vessel of the -floating vessel _u_, _x_, _y_, _z_. The water may be drained off at a -small plug by taking out the floating vessel. The same inconvenience -would arise from a diminution in the proper level of the water. - -In order to ascertain that the governor performs correctly, observe at -the time of lighting or extinguishing any of the burners connected with -it, that its floating vessel rises and falls every time the stop-cock is -opened, and that the lights do not suffer any material change. - -An instantaneous starting or dancing of the lights, is generally -occasioned by an accumulation of water in the tubes through which the -gas passes; if this should happen in the vicinity of the metre and -governor, it may be drained off at the aperture K. A provision for a -like purpose is also made at the bottom of the governor when detached -from the metre. - -In order at any time to ascertain the pressure of the gas in the metre, -close the stop-cock which admits the gas, and open the aperture G and F, -which will shew the level of the water on the scale board E. This being -first observed, close the aperture G, and open the stop-cock, and the -pressure of the gas in the metre will be indicated by the rise of the -water on the scale board E, above its original height. - - - - -PART XII. - - -_Gas Mains, and Branch Pipes._ - -The name of _mains_, is given in the strictest sense of the word, to the -cast-iron pipes from two inches in diameter and upwards, placed under -ground, for conveying the gas into smaller branch pipes; but in a more -extended sense, the term is applied to every pipe from which smaller -ramifications or branch pipes proceed. - -All mains destined to convey coal gas should be proved, they should be -submitted to the trial of sustaining a column of water 300 feet high, -and the pipe should be rejected if the least moisture appears on any -part of the side of the pipe whilst submitted to this trial. For -although such a pipe may remain impervious to gas for some time, the -imperfection or fissure which permits the water to issue through under -such a pressure, speedily increases, in consequence of the moisture to -which the main under ground must necessarily be exposed. A skilful -workman who is in the habit of proving pipes will distinguish, with an -astonishing degree of correctness, a faulty pipe, by the sound produced -by blows of the hammer upon the pipe. The faulty part, when struck upon, -produces a jarring sound very different from the clear sound which a -blow of the hammer produces when the pipe is in a perfect state. By this -means the workman also detects, by the ear, inequalities in the -thickness of the metal of the pipe. - -Fig. 14, plate V., represents a longitudinal section of two flanch -pipes, and the mode of connecting them. _a_, and _b_, are the pipes with -their flanches connected; they are joined together, and rendered -air-tight, by first interposing between the flanches a coat of iron -cement, and then screwing up the faces of the flanches by means of screw -bolts and nuts. - -The composition of the cement is as follows: - -Take four ounces of flour of sulphur, and two of muriate of ammonia, and -mix them intimately together. When the cement is wanted, take five -ounces of the above mixture, and add to it six pounds of cast iron -borings, and blend them intimately together in a mortar; wet the mixture -with water, and when brought to a proper consistence, apply it to the -joints with a wooden or blunt iron spatula. - -A degree of action takes place among the ingredients and the iron -surfaces to which it is applied, which at last causes the whole to unite -into one mass. In fact, after a time, the mixture and the surfaces of -the flanches become a species of pyrites (containing a very large -proportion of iron) all the parts of which cohere strongly together, and -form one mass. It is essential that no larger quantity of the -ingredients of the cement should be mixed up with water, than is -required for immediate use. - -Fig. 15, plate V., represents a longitudinal section of a spigot and -faucet pipe. These pipes are most commonly used as gas mains. _a_, is -called the spigot, _b_, the faucet. The cavity between the inside of -one, and the outside of the other, is partly filled with rope yarn, or -oakum, and a good fitting of the two pipes being thus effected, melted -lead is poured into the cavity, which when set, is hammered in by the -end of a punch. - -The inner parts of the faucet of these pipes ought to be no larger in -diameter than just to fit the spigot. This supports the pipe, -independently of the interposed lead and rope yarn, and prevents the -risk of hurting the joint from any external stress. The inner faucet is -commonly made about two and a half inches deep, and has the spigot -inserted one and a half inch into it. The practice of some manufacturers -is to make the outer faucet, or that which contains the lead six inches -deep, for all pipes above six inches in 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 oakum and lead all -round the spigot, from one inch to one and a quarter inch; that width is -required, in order that the lead 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 lead, and a risk of injury from the -unequal expansion of the two metals. - -All gas mains laid in public streets should be placed at least eighteen -inches below the surface of the ground, to secure them from being -disturbed by carriages, or interfering with the paving of the street; -they should be placed perfectly firm, so that they may not easily give -way. - -The course of all gas mains should be rectilinear, with a dip of about -one inch, in every ten feet distance. - -In all wide streets, where the number of houses on both sides of the -streets, to be supplied with gas, is numerous, it is more economical to -employ a separate gas main for each side of the street, than to make use -of one larger main for both sides; because smaller mains may then be -employed, and the collateral branch pipes leading into the houses are -shorter; these circumstances amply compensate for the additional main. -All _branch_ pipes proceeding from a main, should have a dip of about -one inch in ten feet, towards the main from which they proceed, so that -any fluid that may happen to collect in these pipes must run into the -mains. - -All small wrought iron branch pipes proceeding from the mains into the -houses or places to be lighted with gas, should be covered with a thick -coat of coal tar, before they are laid down into the ground; this may -easily be done by heating the pipe, and laying on the boiled tar with a -brush. - -Every separate length of branch pipe should be tried by condensing the -pipe under water, in order to be certain that the pipe is sound. The -junctures of these pipes should be made by dipping the male screw of the -pipe into a mixture of white lead and linseed oil, before they are -screwed together. - -Notwithstanding the usual care which can be taken in proving pipes, -before the gas is admitted into them, a slight leakage may be sometimes -subsequently detected. - -Therefore, before the gas is suffered to enter the mains, they should be -again proved, in order to be certain that all the junctures are air -tight. The most convenient manner of proving the mains when laid, is by -means of a small portable gas holder filled with common air, and -connected by means of a small pipe, with the system of the mains to be -tried. This gas holder should be made to act with a pressure at least -four times greater than the pressure which the pipes will have to -sustain by the gas they are to convey. If the mains are air tight, the -gas holder will remain stationary, but if they are not sound, the gas -holder will descend, in proportion to the leak of the mains, the -quantity of gas lost may be thus ascertained. - -Every quarter of a mile of pipe should thus be tried separately. In this -manner we become also enabled to detect instantly, whether any -collateral branch pipe has been left open by the workmen, a neglect by -no means uncommon in this department of the gas light business. - -In order to guard against the danger of water entering from the external -surface into the pipes, a reservoir should always be placed at the -lowest point, where two or more descending mains meet and form an angle, -so as to receive the water that may happen to collect at this angular -point, an accumulation of which would cut off the communication between -the two pipes; this reservoir is usually called a siphon, see page 221. -It ought to be at least twice the diameter of the bore of the mains, -between which it is interposed, and four times that diameter in depth. -These reservoirs afford the best indication to show the sound or leaky -state of the system of the mains. In all instances where the pipes are -perfectly sound, observation has shown, that half a mile of gas mains, -three inches in the bore, does not deposit more than a quart of water in -a year; on the other hand, if the mains are leaky, the water of the -reservoir requires to be pumped out, sometimes as frequently as every -fortnight, and during wet weather, much oftener. The loss of gas by such -leakage is much greater than is generally imagined. Instances might be -mentioned where, in order to keep the common air out of a system of -faulty pipes, a constant influx of gas which a pipe two inches in -diameter can supply has been found necessary, and this of course is just -so much gas lost to the economy of the establishment. - -With regard to the diameter of the mains, no general rule can be given. -It must vary according to the number of branch pipes and lamps which the -main has to supply within a given distance,--the angular direction of -the mains,--the pressure of the gas holder, and above all, with the -relative altitude of the place where the gas holder is situated, and the -place at which the gas is to be supplied, or where the lamps are placed. -Indeed this is one of the most important considerations with regard to -the economical distribution of gas mains, and by attending to this -circumstance, a prodigious saving may be effected. - -If the gas flows through a main placed at an altitude of the gas holder, -and with a pressure to support a column of water half an inch high, this -gas at an altitude of 100 feet, will support a column of water ¹¹⁄₁₀ -inch high, and as the velocity of the gas is as the ²√ of the height, or -pressure, the quantity of gas which will flow through a given opening at -an elevation of 100 feet, will be very nearly in the proportion of two -to three. Hence if a gas burner, or gas lamp, produces a flame two -inches high, at a place situated on a level with the base of the gas -holder, the lamp, if supplied by the same main, but situated 100 feet -higher, will burn with a flame three inches high. - -This important fact may be rendered obvious in the following simple -manner: - -Take a tube ten or fifteen feet long, and one inch in diameter, place it -horizontally; let one end of the tube be open, and close the other with -a plate pierced with a hole, of about ¹⁄₃₂ of an inch in diameter, and -then fill the tube with gas. If a lighted taper be applied to the hole, -when the tube is lying horizontally, the gas will not take fire; but on -raising the end of the tube where the small aperture is, the gas will -take fire, and the magnitude of the flame will become enlarged in -proportion as the tube approaches towards the perpendicular. - -Hence the diameter of gas mains must be varied, according to the -altitude of the place to be supplied with gas. And it is in consequence -of neglecting this principle that we observe so frequently certain parts -of large towns scantily supplied with gas, whilst other parts furnished -from the same mains, situated considerably above the level of the gas -holder, have the gas in the greatest profusion, but at the expense of -those places situated at a lower level. And so true is this, that if a -main were to descend 100 feet below the base of the gas holder, and if -the pressure of the gas in the main was only equal to sustain a column -of water half an inch in height, the gas lamps could not be lighted at -all, at a point so low, because the pressure of the gas is then in an -equilibrium with the pressure of the atmosphere. Hence in lighting a -town or district with coal gas, the best situation for the gas -apparatus, as far at least as it regards the economy of the mains for -distributing the gas, is the lowest part of the town or district. For if -the mains are placed at an elevated situation, they require to be -proportionally larger, and if situated at a lower place than the level -of the gas holder, they must be smaller; but in either case the mains -must bear a proper proportion to each other, according to the conditions -and circumstances already stated, and it is here, where the skill of the -gas light engineer becomes conspicuous, for the saving that may thus be -effected in the lighting of a district or town with gas, is very -considerable. - -The requisite pressure of the gas for different situations with regard -to the altitude of the place to be lighted, may be readily known by -ascertaining the altitude of the place by means of the mountain -barometer. The Englefield mountain barometer is most commodious and -suitable for that purpose. This instrument is not liable to be out of -order, it may be used by a single observer, and affords an easy method -of ascertaining the elevations and depressions of the surfaces of the -earth with the greatest facility, and to a degree of precision, that may -vie with trigonometrical mensuration. Thus supposing the pressure of the -gas at the level of the gas holder to be equal to a column of water half -an inch high, by inspecting the height of the barometer, the requisite -pressure of the gas at that place may readily be found. - -That part of a gas main which does not supply any gas to a branch pipe -or lamps, as it proceeds in its course need only be a quarter of the -capacity which is necessary at the part where the branch pipe or pipes -commence. For no inconvenience can arise from the increased velocity -which the gas must assume in proportion to the diminution of the bore -of the main, provided that the velocity of the gas is lessened by -passing into a main of a greater bore, prior to it being conveyed into -the pipe or pipes immediately connected with or supplying the lamps. The -enlargement of the pipes should be in the proportion to the diameter of -the two pipes, as four to one. - - -_Weight of cast iron Gas Mains of different lengths and bores._ - -In order to avoid that the gas mains deposited under ground in public -streets or other places, may not be on the one hand superfluously heavy, -or as it is called _thick in the metal_, and consequently unnecessarily -expensive, and on the other hand not too light, or too thin in the -metal, so as to be liable to become injured, we shall exhibit the weight -of gas mains of different bores and lengths best suited for conveying -gas, now employed at the best regulated gas works in the -metropolis.[50] - - [50] A mile of pipe of an average diameter, laid under ground ready - for conveying gas, together with taking up and making good the - pavement, costs in London, about £. 1000.--And in small towns where - the lights are usually less clustered together than is the case in - London, and where pipes of three inches in the bore are usually - sufficient, a mile of pipe complete costs about £. 700. - - _Bore of _Length _Weight - cast iron pipes._ of pipe._ of pipe._ - INCHES. FEET. POUNDS. - 2 6 46 - 2½ 6 63 - 3 9 120 - 4 9 175 - 5 9 248 - 6 9 280 - 7 9 364 - - - - -PART XIII. - - -_Gas Lamps, and Burners._ - -The lamps or burners for the combustion of coal gas, may be infinitely -and tastefully varied. The varieties commonly employed, are the Argand -burner, the Cockspur burner, and the Bat’s Wing burner. - -The _Argand burner_, fig. 10, and 11, plate V., consists of two -concentric brass tubes, about one and a half inch long, and -seven-eighths of an inch in diameter, (the largest size burner -employed.) The interval between the two tubes is closed at top and -bottom. The upper part is closed with a ring of steel, it is perforated -with fifteen or eighteen holes ¹⁄₃₀ of an inch in diameter. The gas -enters into the cavity between the two tubes, and issues from the -circular row of apertures in the steel ring at the top of the burner -where it is burnt. A double supply of air within and without the flame -is effected by means of the glass which surrounds the flame. The -combustion of the gas is perfect when the admission of air is in due -proportion to the magnitude of the flame. The height of the gas flame -should never exceed three times the diameter of the flame. When the -flame is too large, the light is less brilliant, and it then produces an -odour, because the combustion is imperfect. - -The best shape of the glass for surrounding the gas flame of the Argand -lamp, is a straight tube, shown fig. 8, plate V., or a tube enlarged at -the base, shown fig. 9, plate V. Fig. 10, plate V., is called a crutched -argand gas burner, it is used for pillar lamps; fig. 11, is called a -branch argand burner. - -It is essential that the apertures for the emission of the gas of the -argand gas lamp, be perfectly round and of an uniform size, without this -condition the flame of the lamp is ragged, and not well defined. - -Fig. 15, plate III., exhibits a swing bracket, furnished with a -_cockspur burner_. The burner consists of a hollow flattened globe, -about half an inch in diameter, pierced laterally with three or more -holes, of about ¹⁄₃₀ of an inch in diameter; out of these holes the gas -flame issues in streams as shown in the sketch. With this burner the -combustion of the gas is imperfect, and it is a wasteful mode of burning -coal gas. The surrounding holes of the cockspur burner, was it not for -the upward current of air, would give flames radiating in straight lines -from the centre of the burner, but the ascending current of heated air, -causes them to curve upwards like the spur of a game cock, and hence the -name cockspur burner. - -If the gas be made to burn from a series of holes made in the lateral -circumference of a hollow flat cylinder, it will produce a circular -horizontal series of flames curving upwards. - -Fig. 12. plate V., is called a _bat’s wing_ burner; it consists of a -small pear-shaped steel burner, about ¹⁄₁₆ of an inch in diameter, -having a perpendicular slit at its upper extremity, about ¹⁄₄₀ of an -inch in diameter. This burner exhibits a tulip-shaped flame, as shown -fig. 13, plate V., it is well adapted for street gas lamps. - -The stop-cock for admitting gas into gas burners should always be placed -at least six inches from the burner. The stop-cock in the brackets, fig. -8, or 9, plate V., is placed at _a_. _Pendant gas lamps_, into which the -gas is conveyed from a pipe above, through the ceiling, should be -provided with a mercurial joint, or ball and socket joint. The former -contrivance is preferable, because it can never leak;[51] but the latter -requires occasional repairs. Fig. 14, plate III., shews the mercurial -joint. _a_, is the pipe which brings the gas; it terminates in a sheet -iron cup open at bottom, but closed air tight at the top; this cup is -inverted into a small iron bason, containing mercury. D the iron tube -which communicates with the gas lamp or burner, and the upper extremity -of which projects above the surface of the mercury in the iron bason, -whilst the other extremity proceeds to the burners or lamps. - - [51] This contrivance has been adopted throughout the fitting up of - the gas lights at the Royal Mint. - -_Swing bracket burners_, fig. 13, plate III., should have the axis of -motion at the joints A, A, A, perforated at right angles to each other, -so as to admit the moveable joints at A, to be left open, without -obstructing the passage of the gas when the bracket assumes different -angular positions. All swing brackets ought to have a double, and not a -single joint, because the latter soon wears oval in the two opposite -edges; this is prevented by the double joint having an uniform bearing -at top and bottom, it therefore can never leak. - -Fig. 11, plate VI., exhibits the arrangement usually adopted for a -_pendant perpendicular sliding lamp, or chandelier_, which requires to -be raised or depressed. This contrivance is convenient for lighting -theatres, or public buildings, by means of a large central gas light -chandelier, that may be raised or depressed at pleasure. - -The gas enters into the tube _D_, which is firmly fixed in the ceiling, -as shown in the sketch; it passes through a hole near E, into a smaller -tube _j_, which slides perpendicularly within the tube D. This sliding -tube is made air tight by means of two stuffing boxes filled with oil, -placed near B, and C. The sliding tube _j_, together with the chandelier -suspended to it, is counter-balanced by a weight concealed in a box W, -connected with pullies in the usual manner, as shown in the sketch, so -that the chandelier may be raised or lowered at pleasure. - - -_Directions to Workmen, for adapting Gas Pipes to the interior of -houses._ - -The adapting gas pipes to the interior of houses, for the supply of gas, -simple and easy as it may appear, has been the means of not a little -contributing to bring the gas light illumination, on many occasions, -into disrepute. It has required years to enable workmen of the best -intention to acquire sufficient practical skill in the proper execution -of a business, which must be pronounced to constitute an art entirely -new, and in which no progress could be made, but after having committed -many errors. A house neatly and judiciously fitted up with gas pipes, -displays to a person experienced in this art, a skill and judgment, -equal to what is established in any other branch of mechanical -employment. It must be obvious, that the art of arranging the pipes and -adapting them, is one of that class of operations in which it is a real -saving to employ the best materials and skilful workmen, to avoid -repairs and subsequent alterations and derangements of the work. The -supply and distribution of the pipes, or the _fitting up_, as it is -called by the workmen, may be done almost at any price with regard to -workmanship and materials, and to bargain for cheapness in the execution -of it, with a faithful, honest, and skilful workman, must naturally be a -losing concern to the person for whom the work is done. The cost of -furnishing and adapting the pipes to one place, cannot serve as a -standard for any other place, every separate place may present -difficulties which could not be foreseen at the commencement of the -work. - -The stopping up and corrosion of the gas pipes, which at the -commencement of the introduction of the new lights was complained of in -many places, it is now sufficiently established, originated entirely -from the impurity of the gas, together with a faulty arrangement of the -pipes, in consequence of which, the water of condensation accumulating -in certain parts, exercised a strong chemical action on the copper -pipes, and if the gas was not very pure, ultimately corroded the pipe. -These objections do no longer exist, and it may safely be pronounced, -that pure coal gas produces no action whatever on the copper tubes -through which it is conveyed. In proof of this statement, we need only -refer to the several districts of the metropolis, fitted up with gas -pipes at the first introduction of the new lights, (1809,) all of which -are still in perfect preservation. - -It is perhaps unnecessary to add, that no pipe capable of being melted -by a gas flame, should ever be employed for conveying or distributing -gas through the interior of houses, because the facility with which such -pipes might be perforated, could lead to serious consequences, if the -gas issuing from the aperture of the pipe were lighted, the flame in -that case would follow the melted part, through the whole extent of the -pipe, and the hazard by fire would be considerably increased. -Therefore, pewter, lead, and tin pipes, are very improper for -distributing gas through the interior of houses, and should never be -used for that purpose. Hence copper, and iron pipes, are universally -employed. - -In order that the pipes for conveying the gas from the mains, and -distributing it through the houses or other buildings to be lighted with -gas, may in the first place not be unnecessarily large, or too small, -the following rule may serve as a guide to workmen: - -One gas lamp,--consuming four cubic feet of gas in an hour, if situated -twenty feet distance from the main which supplies the gas, requires a -tube not less than a quarter of an inch in the bore. - -Two lamps,--30 feet distance from the main, require a tube ³⁄₈ of an -inch in the bore. - -Three lamps,--30 feet distance from the main, require a tube ³⁄₈ of an -inch in the bore. - -Four lamps,--40 feet distance from the main, require a tube ¹⁄₂ inch in -the bore. - -Six lamps,--50 feet distance from the main, require a tube ⁵⁄₈ of an -inch in the bore. - -Ten lamps,--100 feet distance from the main, require a tube ³⁄₄ of an -inch in the bore. - -Fifteen lamps,--130 feet distance from the main, require a tube 1 inch -in the bore. - -Twenty lamps,--150 feet distance from the main, require a tube 1¹⁄₄ inch -in the bore. - -Twenty-five lamps,--180 feet distance from the main, require a tube 1⁵⁄₈ -of an inch in the bore. - -Thirty lamps,--200 feet distance from the main, require a tube 1¹⁄₂ inch -in the bore. - -Thirty-five lamps,--250 feet distance from the main, require a tube 1⁵⁄₈ -of an inch in the bore. - -All copper pipes employed to convey gas through the interior of houses -should be of the following weight, with regard to a given length of the -pipe: - - _Bore of the pipe._ _Weight per foot._ - PARTS OF AN INCH. OUNCES. - ²⁄₈ 3 - ³⁄₈ 5 - ¹⁄₂ 6 - ⁵⁄₈ 8 - ³⁄₄ 10 - -No coppered pipes should be used but such as have wrapt over and brazed -joints. They should be well annealed, to render them pliable without -being liable to break. - -All the bends for connecting pipes must be circular, see fig. 22, plate -V. - -No branch pipe ought to proceed from a pipe of a quarter of an inch in -the bore, and no more than two branch pipes should proceed from a pipe -three-eighths of an inch in the bore. - -All branch pipes before they are fixed for conveying gas, must be proved -by condensing air into them by means of a condensing hand pump. The pipe -should be placed in a trough of water, the leak will then be easily -observed by the air bubbles which rise through the water whilst the air -is condensed in the pipes. - -All branch pipes should have a rectilinear course; pipes that are -twisted have an unsightly appearance. - -All pipes should have a descent of no less than a quarter of an inch in -four feet. - -The seams or brazed part of the pipes must always be out most and not -towards the wall; because if a leak should happen to take place in the -brazed part of the pipe, it may then be easily discovered and more -readily repaired. - -When all the pipes have been furnished to a house or place intended to -be lighted, the whole system of the pipes should be examined with the -utmost rigour, to ascertain whether all the junctures are air tight. -This should be done by condensing air into the pipes by means of a -condensing syringe, and if the piston of the syringe lowers after -condensation, it is a sure indication that the pipes are faulty, and -consequently totally unfit for receiving the gas. The leak may be -detected by passing a lighted taper carefully along the whole extent of -the pipe filled with condensed air, when the flame of the taper will be -affected as it passes over the faulty place of the pipe. - -The aperture from which the gas can escape may however, be so small, as -to render it a matter of difficulty to discover it in the manner just -stated; but when the pipes are filled with coal gas, the escape of it, -when all the stop-cocks of the lamps and burners are shut, will soon -become obvious, by the peculiar odour of the gas, if the apartment, or -place, where the pipes are placed, is suffered to be closed for about -twenty-four hours. The gas should not be introduced into pipes in which -any defect of this kind is found, until it be completely removed. The -most severe trial to ascertain the air tightness of any system of pipes -is, the trial by exhaustion, by means of an air pump, for the guage of -the pump will discover the minutest leak, which the preceding method of -proving pipes can not discover. - -All pipes after being proved should be painted of the same colour as the -surface to which they are affixed. - -The whole system of pipes should incline to one or more places, so that -any moisture that may happen to accumulate in the pipes, may collect at -such places, whence it may be readily removed by opening a screw plug -adapted for that purpose. - -All the different junctures of mains and branch pipes, should be -effected by means of connecting pieces, so that any part of the system -of the pipes, or any separate branch pipe may readily be detached, and -put up again if occasion should require it; fig. 19, plate V., exhibits -this mode of connecting gas pipes by means of union joints. A, B, C, D, -E, shows a gas pipe with its union or connecting joint, divided into its -separate parts. _D_, is a collar of leather, which passes over the part -C, of the union joint, close up to the shoulder of the joint; the -opposite extremity of the pipe may be inserted into the socket _B_, so -that the shoulder C, comes in contact with the fillet or rim in B, to -prevent it passing over the shoulder C, when B and E are screwed -together. The latter part of the pipe is furnished with a male screw to -correspond with the thread in the collar B. The shoulder piece C, is of -rather a larger diameter than the bore of the tube A, with which it is -to be connected. The short piece E, furnished with a male screw, is of -the same diameter as the part C. The pieces C, and E, of the pipe are -soft soldered, one to the tube A, and the other to the tube E, but -previous to soldering on C, it is necessary that the socket should be -inserted into the tube A, it will then be ready for connecting, as will -become obvious by inspecting fig. 20, which shows the various parts of -the union joint fitted for use. It is evident that if the extremity D, -in the pipe B, be brought close to the pipe E, and if the socket C, be -moved along the pipe A, and screwed upon the male screw at D, as far as -it will go, the face of the part D, must press close against the leather -collar which is placed on E, and render the joint gas tight. These kind -of joints are very convenient for circular bends, fig. 22, and T, -pieces, fig. 21. The T pieces, fig. 21, are very useful for collateral -branch pipes, either for the same or of a less diameter as the pipe, -from which they proceed, so as to branch off at right angles. - -Fig. 22, is a quarter circular bend; it is convenient for adapting tubes -along the angular parts of rooms, and to all such situations where the -tube is to have a sudden circular course. Small copper tubes may be -readily bent to the required angle without breaking, but if a tube -should terminate in any angular part of a room, in that case a circular -bend furnished with a male and female screw, is convenient for -connecting the pipes together. - -All pipes adapted to the exterior of buildings, should be kept a little -distance off from the wall, to prevent the wet lodging between the pipe -and the surface to which they adapted. - -Sheet iron mains for the interior of houses, are preferable to copper -mains, provided the course of the main with regard to the position of -the branch pipes, does not require too many angular directions, or -circular bends. - - - - -PART XIV. - - -_Illuminating power of Coal Gas, and quantity of Gas consumed in a given -time, by different kinds of Burners, and Gas Lamps._ - -The illuminating power of coal gas, differs according to the nature of -the coal from which it is obtained, and the manner in which it is -purified, together with the quantity of naptha or essential oil -chemically combined, or mechanically suspended in the gas. For if the -gas be strongly agitated with water, its illuminating power is -diminished. Coal gas, which abounds in olifiant gas or supercarburetted -hydrogen possesses the greatest illuminating power, and hence -carburetted hydrogen obtained from the decomposition of coal tar -possesses a greater illuminating power than the gas obtained from the -coals which produced the tar. The illuminating power of carburetted -hydrogen obtained from coal tar when compared to the gas obtained from -the best Newcastle coal is in the proportion as six to five. In fact the -intensity of light evolved during the combustion of gazeous bodies -composed of carbon, hydrogen, and oxigen, is always in the ratio of the -quantity of carbon contained in equal quantities of the gazeous -compound, and hence the gas from animal oil which is chiefly composed of -supercarburetted hydrogen or olifiant gas, surpasses in illuminating -power the gas obtained from coal. - -Half a cubic foot of coal gas, obtained in the ordinary way of -manufacturing coal gas, from Newcastle coal, is equal in illuminating -power and duration of time, to the light produced by a tallow candle six -in the pound, burning for one hour, and as such a tallow candle lasts -five hours, therefore fifteen cubic feet of coal gas, are equal in value -with regard to illuminating power to one pound of candles. And as 112 -pounds of Newcastle coal produce by the new method of manufacturing coal -gas, at least 550 cubic feet of gas, therefore the quantity of gas -produced from a chaldron of Newcastle or Sunderland coal, (the minimum -weight of which is 27 cwt.) is equal in illuminating power to 1000 -pounds of tallow candles. - -The illuminating power of coal gas may readily be ascertained. Though -the eye is not fitted to judge of the proportional power of different -lights, it can distinguish in many cases with sufficient precision where -two similar surfaces are equally illuminated. As the lucid particles -emitted from luminous bodies are darted in right lines, they must spread -uniformly, and hence their density diminishes in the duplicate ratio of -their distance. From the respective situations, therefore, of the -centres of divergency, when the contrasted and illuminated surfaces -become equally bright, we are enabled to compute their relative degrees -of intensity. And 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 -object, 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 the two sources of light to such distances from an object that -they may illuminate it in equal degrees, we are authorized to 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 opaque 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 -make the shadow which it produces equal to that afforded by the less -light. Experiments of this kind may be made in the following manner: - -Fasten a sheet of white paper against the wall of a room, and place the -two lights intended to be compared, so that the rays of light from each -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 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 experiments of this kind, many useful particulars may be shewn; for, -since the cost and duration of candles, and the consumption of coal gas, -or oil in lamps, are easily ascertainable, it may be shewn whether more -or less light is obtained at the same expense during a given time, by -burning a number of small lights, instead of one or more of greater -intensities. And thus we may compare the power of different kinds of -lamps or candles, with gas lights of different intensities, 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 light be -required, and the candle kept 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 or chemical constitution of the coal gas. The -bulk of the gas consumed, and the weight of tallow or oil used by -weighing the candle or oil before and after the experiment furnish the -data for calculating the relative cost of tallow, or oil and gas, when -compared with each other. - -The following statement exhibits the quantity of coal gas consumed in a -given time, by different kinds of argand lamps. An argand burner which -measures in the upper rim half an inch in diameter, between the holes -from which the gas issues, when furnished with five apertures ¹⁄₂5 part -of an inch in diameter, consumes two cubic feet of gas in an hour, when -the gas flame is one and a half inch high. The illuminating power -produced by this burner is equal to three tallow candles eight in the -pound. - -An argand burner three quarters of an inch in diameter between the -holes in the upper rim, and perforated with holes, ¹⁄₃₀ of an inch in -diameter, consumes three cubic feet of gas in an hour, when the flame is -two and a quarter inches high, and produces a light equal in intensity -to four tallow candles, eight in a pound. - -An argand burner seven-eighths of an inch in diameter, perforated with -eighteen holes ¹⁄₃₂ of an inch in diameter, consumes when the flame of -the gas is three inches high, four cubic feet of gas in an hour, and -produces a light equal in intensity to six tallow candles, eight in the -pound. - -When the flame obtained by these kind of burners rises to a greater -height, than what has been stated, the combustion of the gas is -imperfect, the intensity of the light becomes diminished, and there is a -waste of gas. The same holds good with regard to the size of the holes -from which the gas issues; if the holes be made larger than ¹⁄₂5 part of -an inch in these kind of burners, the gas is not completely burnt, and -its illuminating power decreases. - -The height of the glass which surrounds the flame, should never be less -than five inches, and the interval for the current of air within and -without the flame, ought to bear the usual proportion adopted for the -combustion of oil in the common argand lamps of similar diameters. - - -_Ventilation of Apartments lighted by Coal Gas._ - -Before means had been devised for the effectual purification of coal -gas, a disagreeable odour was found to attend its combustion in an -impure state, and hence an opinion became prevalent, that the benefit of -this new species of illumination must be confined to open places, and -that it could not with any regard to pleasure or salubrity, be adapted -to private dwellings. - -The art of purifying coal gas, has at length however, been carried to -such a perfection, that every possibility of a disagreeable odour -arising from its combustion has been wholly removed, in all cases where -attention is paid to the perfect combustion of the gas, by keeping the -flame of the same of a proper magnitude. - -And since this improvement, the use of coal gas, as a means of -illumination has become as general, and has been found attended with as -superior advantages within doors as without, and hence a vast number of -dwelling houses are now lighted throughout with gas. - -Although there is no occasion therefore, to make provision for -ventilating apartments where gas light is employed, on account of any -odour which it can produce when honestly used, so that the combustion is -perfect, yet on other accounts such means of ventilations are very -salutary and necessary. - -The flame of coal gas produces a degree of heat,[52] which in some -places, such as large public offices, and warehouses of dry goods, is a -strong additional recommendation in favour of its use, (page 15,) while -in others, on the contrary, such as small rooms numerously frequented, -and shops containing commodities requiring to be kept cool, it can only -be used beneficially when means are provided for conveying away the -heated air. - - [52] Mr. Dalton’s method of ascertaining the comparative effect of - heat evolved during the combustion of inflammable gases, and other - substances capable of burning with flame, (Dalton’s System of - Chemistry, vol. I. p. 76,) is simple, easy, and accurate. It is as - follows: - - Take a bladder of any size, (let us suppose for the sake of - illustration, the bladder to hold 30,000 grains of water,) and having - furnished it with a stop-cock and 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 bulk of the water in the bladder, viz. 30,000 grains. Then set - fire to the gas at the orifice of the pipe, 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 before - and after the experiment, expresses very accurately the heating power - of the given bulk of the inflammable gas. It was thus proved that-- - - Olifiant gas raises an equal volume of water 14 deg. - Carburetted hydrogen, or coal gas 10 - Carbonic oxid gas 4 - Hydrogen gas 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 - - -The best method for this purpose is to make an aperture of about two or -three inches in diameter into the chimney near the ceiling, and -inserting into it a tube bending upwards into the interior of the -chimney. A complete ventilation of the room will thus be established, by -producing an extra vent which will be amply sufficient for carrying off -the heated air. The aperture can easily be masked with some ornamental -open work, corresponding with the style of the room. - -If there happens to be no chimney in the apartment, the ventilator may -be made in the ceiling, and the tube may be carried between the ceiling -and the floor above, into the open air. The mode of ventilation now -suggested, has been uniformly found most efficient, and has, under -existing circumstances, a decided superiority over another method, which -we see in some instances adopted. This method consists in enclosing the -gas burner in a bell-shaped glass, from the upper part of which a large -copper tube proceeds, and leads out into the open air. It is certain -that by this means not only the heated air is carried off, and the -possibility of any waste gas escaping into the apartment is also -completely prevented. But at the same time, by taking away all occasion -for a prudent limitation in the use of the gas, it exposes it to a -degree of improvident waste, in the hands of dishonest and careless -individuals, which must prove ruinous to the manufacturer. The mode of -regulating the light of the flames by means of the governor, of which a -description has been given, page 232, indeed provides a check against -such waste, and there can be no doubt that in proportion as this -instrument gets into general use, the objection on this score must of -course fall to the ground; but under any circumstances the inelegance of -the contrivance of such an object in a chamber, as the large branching -tube, must always induce a preference, for the more simple, and for all -necessary purposes, equally efficient method, of the ventilator before -described. - - - - -PART XV. - - -_Gas from Coal Tar._ - -Although the tar which forms one of the products obtained from the -decomposition of pit coal, in the manufacture of coal gas, has become an -article of commerce, being found applicable to most of those purposes to -which vegetable tar has hitherto been used, it appears from experiments -made on a large scale, that instead of thus disposing of the coal tar, -it is more profitable, under certain circumstances, to submit this -substance to a destructive distillation, for the purpose of obtaining -from it carburetted hydrogen gas, which it is capable of affording, not -only in abundance, but of a superior quality. - -The chief circumstances which must determine the manufacturer of coal -gas in this respect, is the price at which he can sell the coke produced -in his establishment. If the price of this article is high, if he finds -a ready market for coke, there is every reason to believe, that the -manufacturer will find it more to his advantage to dispose of the tar, -and to manufacture gas from coal alone, in order to increase his store -of coke. But if coke happens to be at a low price, and not disposable -with advantage, the manufacturer will do well to make the coal go as far -as possible in the production of gas, and under such circumstances he -will keep and convert the tar into gas, thus consuming less coal and -having less of the burdensome article, coke, to dispose of. - -The profit however, to be gained from the sale of coke, must be both -certain and considerable, to induce a preference for the former course; -because the decomposition of coal tar, besides superseding a -proportionate quantity of coal, is attended with several other very -tempting advantages. - -From experiments lately made in the metropolis on this subject, in which -I have been engaged, it appears that in all large gas light -establishments, where the quantity of coal tar rapidly accumulates, and -must be got rid of, and in all places where the tar cannot be sold for -more than four shillings the hundred weight, it will be certainly -advantageous to the manufacturer to decompose the tar for the production -of carburetted hydrogen gas. - -The price of coal cannot effect the operation, because where coal bears -a high price, the manufacturer of the tar gas, will diminish the -quantity of coal which he would otherwise be called upon to employ for -the production of the requisite quantity of gas. And in places where -coal is cheap, the decomposition of the tar will be attended with less -expence. - -The carburetted hydrogen gas produced from coal tar, possesses a greater -illuminating power than the gas obtained from coal.[53] It consists -chiefly of supercarburetted hydrogen or olifiant gas, and a less -quantity of it is of course sufficient. - - [53] Vegetable tar, also affords carburetted hydrogen gas in - abundance, and this no doubt might be employed to great advantage for - the production of artificial light in places where it is cheap. 212 - pounds of the most viscid Swedish tar, produce 1484 cubic feet of - carburetted hydrogen, (or seven cubic feet to one pound of tar,) the - illuminating power of this gas is equal to the gas obtained from pit - coal. - -The gas thus obtained, is purified likewise with far greater facility, -taking only one hundred and twentieth part of the quantity of quicklime -which is required for the purification of carburetted hydrogen obtained -from pit coal. The apparatus for the production of carburetted hydrogen -from coal tar, is moreover less bulky, less expensive, and less -complicated; and it can be managed by fewer workmen. And as the combined -result of these several advantages, it is obvious, that by the -substitution of coal tar, the new mode of lighting by gas can be pursued -on a smaller scale; which it can never be with any profit, where coal -itself is immediately employed for the production of the gas. - -The apparatus employed by Mr. Clegg, for the distillation of tar, is -extremely simple. It consists of two hollow cast iron cylinders, twelve -inches in diameter, and nine feet long, furnished with moveable lids or -mouth pieces, and joined together at the extremity opposite to the mouth -piece. These cylinders are fixed in a brick furnace, so that each -inclines eleven degrees, one above and the other below the horizontal -base of the furnace. - -When the apparatus has acquired a dull red heat, the coal tar is -suffered to flow into the upper cylinder, by small portions at a time. - -The tar is contained in a closed vessel, situated at any convenient -place above the apparatus. It has a small aperture for the admission of -air. But as a sufficient small quantity of viscid tar does not flow -freely in a thin stream, a larger portion than is wanted, is made to -flow first into a a small box, upon the apex of a pyramid which divides -the stream, so that the excess runs off by a waste pipe, whilst a due -quantity only is conveyed into the retort where it is decomposed. - -This apparatus[54] therefore differs only from the apparatus described -in the Journal of Science and the Arts, 1816, No. II., p. 282; that the -cylinders may be detached, for cleaning them out more conveniently. - - [54] Now erecting at Birmingham. - -The following statement exhibits the result of a series of experiments, -made (1816,) at the Westminster Chartered Gas Light Establishment,[55] -for the purpose of ascertaining how far, and under what circumstances -the decomposition of coal tar is a measure of economy. - - [55] Communicated by Mr. T. S. Peckston. - - Two tar retorts worked seven hours, produced 3054 cubic feet of gas. - The quantity of tar decomposed, amounted to 354 lb. therefore 8 cubic - feet of gas, (omitting fractions), were obtained from 1 lb. of tar. - - Two tar retorts, worked nine hours, produced 4591 cubic feet of gas. - The quantity of tar decomposed, was 525 lb. Hence 1 lb. of tar yielded - nearly 8³⁄₄ cubic feet of gas. - - Fifteen cwt. 16 lb. of tar, produced 16,112 cubic feet of gas, = 9¹⁄₂ - cubic feet of gas, to 1 lb. of tar. - - Five cwt. 3 quarters, 22 lb. of tar, produced 6660 cubic feet of gas, - = 10 cubic feet of gas to 1 lb. of tar. - - Five cwt. 17 lb. of tar, produced 5193 cubic feet of gas, = 9 cubic - feet of gas to 1 lb. of tar. - - One cwt. 81 lb. of tar, produced 1737 cubic feet of gas, = 9 cubic - feet of gas to 1 lb. of tar. - - One cwt. 30 lb. of tar, produced 1313¹⁄₂ cubic feet of gas, = 8 cubic - feet of gas to 1 lb. of tar. - - Five cwt. of tar, produced 5880 cubic feet of gas, = 10¹⁄₂ cubic feet - of gas to 1 lb. of tar. - - Two cwt. of tar, produced 2072 cubic feet of gas, = 9¹⁄₂ cubic feet of - gas to 1 lb. of tar. - - Three cwt. 18 lb. of tar, produced 3717 cubic feet of gas, = 10¹⁄₂ - cubic feet of gas to 1 lb. of tar. - - Two cwt. 6 lb. of tar, produced 2242¹⁄₂ cubic feet of gas, = 9³⁄₄ - cubic feet of gas to 1 lb. of tar. - -From the preceding operations it becomes obvious, that 9¹⁄₂ cubic feet -of gas, were obtained in the large way from 1 lb. of tar. But this -proportion appears evidently too small, our own operations assign -fifteen cubic feet of gas to one pound of tar. Professor Brande, -obtained eighteen cubic feet[56] from the same quantity of tar. - - [56] Journal of Science and the Arts, 1816, No. II. p. 282. - - -_Gas from Oil._ - -“Messrs. J. and P. Taylor[57] are the first persons who have resorted to -oil as a substance from which gas for illumination could be easily and -cheaply prepared; and in the construction of a convenient apparatus for -the decomposition of this body, they have fully shewn its numerous -advantages over coal, while they have afforded the means of producing -the most pure and brilliant flame from the inferior and cheap oils, -which could not be used in lamps. The apparatus for the purpose is much -smaller, much simpler, and yet equally effectual, with the best coal gas -apparatus. The retort is a bent cast iron tube, which is heated red by a -small convenient furnace, and into which oil is allowed to drop by a -very ingenious apparatus; the oil is immediately volatilized, and the -vapour in traversing the tube becomes perfectly decomposed. A mixture of -inflammable gases, which contains a great proportion of olifiant gas -passes off; it is washed by being passed through a vessel of water -(which dissolves a little sebacic acid, and which seldom requires -changing), and is then conducted into the gasometer.” - - [57] Copied from the Journal of Science and the Arts, Vol. VI. p. 108. - -“The facility and cleanliness with which gas is prepared from oil in the -above manner, may be conceived from the description of the process. A -small furnace is lighted, and a sufficient quantity of the commonest oil -is put into a small iron vessel, a cock is turned, and the gas after -passing through water in the washing vessel, goes into the gasometer. -The operation may be stopped by shutting off the oil, or, to a certain -extent, hastened by letting it on more freely; the small quantity of -charcoal deposited in the retort is drawn out by a small rake, and the -water of the washer is very rarely changed.” - -“The gas prepared from oil is very superior in quality to that from -coal; it cannot possibly contain sulphuretted hydrogen, or any -extraneous substance; it gives a much brighter and denser flame; and it -is also more effectual, i. e. a lesser quantity will supply the burner -with fuel. These peculiarities are occasioned, in the first place, by -the absence of sulphur from oil, and then by the gas containing more -carbon in solution. As the proportion of light given out by the flame of -a gaseous compound of carbon and hydrogen, is in common circumstances in -proportion to the quantity of carbon present; it is evident that the gas -which contains a greater proportion of olifiant gas, or supercarburetted -hydrogen than coal gas, will yield a better and brighter light on -combustion.” - -“It is necessary, in consequence of the abundance of charcoal in -solution, to supply the gas when burning with plenty of atmospheric air, -for as there is more combustible matter in a certain volume of it, than -in an equal volume of coal gas, it of necessity must have more oxigen -for its consumption.[58] The consequence is, that less gas must be burnt -in a flame of equal size, which will still possess superior brilliancy; -that less is necessary for the same purpose of illumination; and that -less heat will be occasioned. From five and a half to six cubical feet -of coal gas are required to supply an Argand burner for an hour; two -cubical feet to two and a half of that from oil, are abundantly -sufficient for the same purpose.” - - [58] Dr. W. Henry’s experiments gave the following result:--100 cubic - inches of carburetted hydrogen from coal, require, for burning, 220 - cubic inches of oxigen, and produce 100 cubic inches of carbonic - acid--100 cubic inches of carburetted hydrogen gas procured from lamp - oil, require 190 cubic inches of oxigen, and produce 124 cubic inches - of carbonic acid,--100 cubic inches of carburetted hydrogen obtained - from wax, require 280 cubic inches of oxigen, and produce 137 cubic - inches of carbonic acid. - -“One important advantage gained by the circumstance, that so small a -quantity of this gas is necessary for burners is, that the gasometer -required may be small in proportion. The gasometer is the most bulky -part of a gas apparatus, and that least capable of concentration; and -where-ever it is placed, it occupies room to the exclusion of every -thing else. Some very ingenious attempts have been made to diminish its -size and weight, as in the double gasometer,[59] and others, but without -remarkable success. Here, however, where the room required to contain -the gas is directly diminished, the object is so far obtained; and when -that takes place to one half, or even one third, it is of very great -importance. It in a great number of cases brings the size of the -apparatus within what can be allowed in private houses; and in -consequence of the rapidity with which the retort can be worked, the -gasometer may again be reduced to a still smaller size.” - - [59] This contrivance is more expensive and complicated than any of - the gas holders of which a description has been given; nor is it safe, - for if the slightest leak should happen in the interior vessel of the - double gas holder, an explosive mixture would be formed, and dreadful - consequences might follow; this can never be the case with any of the - machines now in use.--_Note of the Author._ - -“Another advantage gained by the small quantity of gas required for a -flame, is the proportionate diminution of heat arising from the lights. -The quantities of heat and light produced by the combustion of -inflammable gases are by no means in the same constant relation to each -other; one frequently increases, whilst the other diminishes; and this -is eminently the case when coal gas and oil gas are burned against each -other. The quantity of heat liberated is, speaking generally, as the -quantity of gas consumed, and this is greatest with the coal gas; but -the quantity of light is nearly as the quantity of carbon that is well -burnt in the flame, and this is greatest in the oil gas.” - -“The very compact state in which the apparatus necessary for the -decomposition of oil can be placed, the slight degree of attention -required, its certainty of action, its cleanliness, and the numerous -applications which it admits of in the use of its furnace for other -convenient or economical purposes, render it not only unobjectionable, -but useful in manufactories and establishments; and these favourable -circumstances are accompanied, not from any inferiority in the flame or -increased expense, but by an improved state of the first, and saving in -the latter.” - -“Messrs. Taylor have shewn great ingenuity in the construction of their -whole apparatus, but the washer and gasometer deserve particular notice -for their remarkable simplicity also. In the washer, two planes are -fixed in a box or cistern, in a direction not quite horizontal, but -inclined a little in opposite directions; the planes are traversed -nearly across by slips of wood or metal, fixed in an inclined position -on the under surface, and which alternately touch one side of the -cistern, leaving the other open and free. These planes being immersed in -water, the gas is thrown in under the lowest ridge, and by its ascending -power is made to traverse backward and forward along the ridges fixed -on the planes, until it escapes at the highest part of the uppermost -ridge. Thus, with a pressure of five or six inches of water only, it is -made to pass through a distance of fourteen or sixteen feet under the -surface of the fluid, and becomes well washed.” - -“The smaller gasometers are made of thin plate iron, and being placed in -a frame of light iron work, look more like ornamental stoves than the -bulky appendages to a gas apparatus, which they supply. The larger ones -are made very light, and when in pieces very portable, by being -constructed of a frame of wood work, in the edges of which are deep -narrow grooves; plates of iron fit into these grooves, which being -caulked in and painted over, make a light and tight apparatus. These are -easily put together in any place, and may therefore be introduced into a -small apartment, or other confined space, where a gasometer already made -up would not enter.” - -For the following additional information on this subject, I am indebted -to Messrs. J. and P. Taylor. - -“The economy of obtaining gas for the production of light from oil, may -be judged of from the following data.” - -“One gallon of common whale oil, produces about ninety cubic feet of -gas.[60] An argand burner required a cubic foot and a half of gas per -hour; and consequently a gallon of oil when converted into gas, will -supply the same burner for sixty hours. The expence of the gas at a -moderate price of oil, will be, allowing for coals, labour, &c. for -producing the gas, three farthings per hour, and such a burner will give -a light, equal in intensity, to two argand lamps, or ten mould candles.” - - [60] Our experiments produced 105 cubic feet, from one gallon of - common whale oil.--_Note of the Author._ - -“The expence of an argand oil lamp, is usually admitted to be, about -three halfpence per hour. Now supposing ten candles to be burning, four -to the pound (two pound and a half,) they will cost 2_s._ 11_d._ of -which one-tenth part will be consumed in each hour. The cost of the -tallow light is then three pence halfpenny per hour.” - -“If wax candles be employed, the expence of the light equal to an oil -gas burner for one hour, by the same mode of reckoning, allowing the -candle to burn ten hours, and taking the price of the wax candles, at -4_s._ 6_d._ per pound, will be about 14_d._” - -“The comparative account will therefore stand thus: - - PENCE. - Cost of an Argand burner, supplied with oil gas, per hour 0³⁄₄ - Ditto of an Argand lamp, burning spermaceti oil 3 - Ditto of Tallow mould candles 3¹⁄₂ - Wax candles 14 - -“These calculations on the cost of light from oil gas, are taken at the -usual price of good whale oil, but cheaper oils will answer the purpose -nearly as well, and as many of these are often to be procured, the whole -expence becomes materially reduced by their use.” - - - - -PART XVI. - - -_Other products obtainable from Coal, namely:--Coal Tar--Pitch--Coal -Oil--Ammoniacal Liquor, and conversion of the latter into Carbonate, and -Muriate of Ammonia._ - - -_Coal Tar._ - -The coal tar is so called from its resembling common tar in its -appearance, and most of its qualities. - -This substance is deposited in the purification of the coal gas, in a -separate vessel destined to receive it. See fig. 3, plate I. - -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. - -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 -have 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 the coke, but, at the same -time, to save and collect the tar. Even this process, however, for which -a patent was taken out, gained very little ground. Its object was too -limited; for though some of the proximate constituent parts of coal were -procured, they were obtained at an expence that nearly balanced the -profits; and no attention whatever was paid to the coal gas, which -constitutes by far the most valuable part obtainable from pit coal. - -Coal tar is now used with advantage largely in the Royal Navy, and also -for painting and securing wood that is exposed to the action of air. The -wood being warmed, the tar is applied cold, and penetrating into the -pores, gives the timber an uncommon degree of hardness and durability. - -The quantity of tar obtainable from a given quantity of coal, varies -according to the manner in which the decomposition of the coal is -affected. See page 122. - -The tar obtained from Newcastle coal 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 coal 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 by the name of - - -_Coal Oil._ - -To obtain this oil, a common still is charged with 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 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 naptha, which is very useful in painting ships, and for making -common varnishes. It has lately been employed as a substitute for whale -oil, to be burnt in out door lamps. - -The contrivance by means of which this oil is burnt in lamps[61] -consists of a fountain reservoir to supply and preserve a constant -level. The burner with its wick is placed in the axis of the lamp, and -supplied with the oil from the fountain reservoir, placed on the outside -of the lamp. The air is admitted by an aperture at the bottom of the -lamp. The current of air in passing through the lamp envelopes the -burner and urges the flame, which is extremely bright; but it is -essential that the flame should be small. The draught tube proceeding -from the centre of the reflector above the flame carries away the smoke. - - [61] All the lamps on Waterloo Bridge, and the streets adjoining the - bridge are lighted by means of tar oil. - -1430 pounds of coal tar, produce 360 pounds of essential oil. The -residue left after the distillation is - - -_Pitch._ - -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 spout or rim is added 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. - -1430 pounds of coal tar produce 9 cwt. of pitch. A subsequent -evaporation with a gentle heat, converts the coal pitch into a substance -greatly resembling _asphaltum_. - - -_Manufacture of Carbonate of Ammonia from the Ammoniacal Liquor of Pit -Coal._ - -The ammoniacal liquor obtained in the gas light manufacture, is employed -for the production of carbonate of ammonia. The average quantity of this -liquor, obtainable from a chaldron, (27 cwt.) of Newcastle, or -Sunderland coal, amounts to from 180 to 220 pounds. It is chiefly -composed of carbonate and sulphate of ammonia. The quantity of ammonia -contained in it, varies considerably. The strongest liquor is obtained -from coal that readily cake, (page 45); a gallon (or eight and a half -pounds weight) of ammoniacal liquor usually requires for saturation, -from fifteen to sixteen ounces of sulphuric acid of a specific gravity -1,84. The weakest ammoniacal liquor is obtained from those species of -coal which do not cake, and which by a single combustion are reduced to -light ashes. It requires only from eight to ten ounces of sulphuric -acid, of the before mentioned specific gravity for its saturation. - -The following process is employed in the large way, for obtaining -carbonate of ammonia from the ammoniacal liquor. To 108 gallons[62] of -the liquor contained in a cask, are added 125 pounds[63] of finely -ground sulphate of lime, which has been previously deprived of moisture -by heat. The cask is bunged up, and the mixture after being stirred -together for a few minutes, is left undisturbed for three or four hours. -Sixteen ounces of sulphuric acid are then added, the mixture is again -agitated, and is again suffered to stand undisturbed for four or six -hours. If the liquor be now examined, it will turn blue litmus paper, -red. - - [62] One gallon of the strongest ammoniacal liquor, weighs eight and a - half pounds. - - [63] This quantity is evidently too large, but the workmen assert, - that an excess of sulphate of lime causes the carbonate of lime which - is formed, to subside more readily, and the excess of sulphate of lime - can do no injury. - -In this operation a double decomposition takes place, the sulphate of -lime yields part of its sulphuric acid, to the carbonate of ammonia of -the liquor, to form sulphate of ammonia, and the carbonic acid of the -ammonia, combines with the lime of the sulphate of lime, to form -carbonate of lime, which falls to the bottom, the supernatant fluid -contains in solution, sulphate of ammonia. - -When the liquor has become clear, it is pumped out of the barrel into -shallow cast iron boilers, where it is evaporated slowly. During this -process, a portion of sulphate of lime is deposited which is removed, -and as the liquor becomes more concentrated, part of the sulphate of -ammonia begins to crystallize and falls to the bottom. It is shovelled -out from time to time into wicker baskets, placed slanting over the rim -of the boiler, that the liquor which drains off from the crystals may -not be lost, and lastly the whole fluid is evaporated to dryness. - -108 gallons of ammoniacal liquor from Newcastle coal, produce upon an -average, one and a half cwt. of dry sulphate of ammonia. To decompose -it, one cwt. is mixt with one quarter of a cwt. of finely ground chalk, -previously deprived of moisture by heat. The mixture is introduced (as -expeditiously as possible) into cast iron retorts,[64] heated nearly to -a dull redness, and when the lid of the retorts have been rendered air -tight, the fire is raised gradually till the retorts are of a strong red -heat. The carbonate of ammonia developed from the contents of the -retorts, is made to sublime into a leaden barrel-shaped receiver, -connected with the retorts, by means of a pipe four inches in diameter, -proceeding from the upper extremity of each retort, and opposite to the -mouth piece. The leaden receiver is furnished with a leaden cover, -fitting into a groove, where it is made air tight by lute. The receiver -which is supported upon a stand is provided at its base, with a small -pipe, furnished with a stopper. This pipe is left open till the liquid -products are got rid of during the sublimatory process. In the centre of -the cover, or at any other convenient part of the apparatus, is made a -small hole, slightly stopped with a wooden peg, to give vent to the -elastic fluid that becomes evolved during the process. - - [64] Of the usual form and dimensions, described page 58. - -The time requisite for the operation depends on the mode in which the -retorts are set, the temperature kept up and other practical -circumstances. A charge of 120 pounds of the mixture of sulphate of -ammonia and chalk in one retort, is usually decomposed in twenty-four -hours. When the operation is at an end, and the receiver having become -cold, the cover is taken off, and the sublimed carbonate of ammonia -adhering to the sides of the receiver is detached by a chissel and -mallet, and after being freed from any casual impurities, is packed up -in stone jars for sale. - -One cwt. of dry sulphate of ammonia, produces from sixty pounds, to -sixty-five pounds, of pure carbonate of ammonia. In some establishments, -the carbonate of ammonia is subjected to a second sublimation by means -of a gentle heat; but this is quite unnecessary if the process has been -conducted carefully. - - -_Manufacture of Muriate of Ammonia from the Ammoniacal Liquor of Coal._ - -It must be obvious that the ammoniacal liquor may be employed with great -advantage for the production of muriate of ammonia. For if the solution -of sulphate of ammonia obtained from the ammoniacal liquor by means of -sulphate of lime, as before stated, be mixed with common salt, (or any -other muriate) another decomposition takes place. The muriatic acid of -the common salt, unites to the ammonia of the sulphate of ammonia, and -produces muriate of ammonia, and the sulphuric acid of the sulphate of -ammonia, combines with the soda of the common salt, and produces -sulphate of soda, or glauber salt. - -The liquor containing these two salts being evaporated, the glauber salt -begins to crystallize, and is removed from time to time. The evaporation -is continued till as much as possible of the glauber salt has been -separated, and the muriate of ammonia begins to crystallize on the -surface of the fluid in the form of a feathered star. The remaining -fluid is then run off into coolers, and deposits little else than -muriate of ammonia, till it gets below the temperature of 76° Fahr. at -which time the crystals are to be removed, lest they should be mixed -with glauber’s salt which now begins to be again deposited. After the -muriate of ammonia has been suffered to drain in baskets, it is heated -in shallow pans to drive off as much water of crystallization as -possible. It is then removed whilst still hot, into earthenware jars, -glazed within, and fitted with a cover, (having a hole of about half an -inch in diameter in its centre,) luted on with clay. The jars are put in -a cast iron pot over a strong fire, in a furnace capable of containing -from six to eighteen jars, surrounded with sand up to the edge of the -pot, and also having about two and a half inches of sand on the cover, -confined by an iron ring about three inches deep, and two inches less in -diameter than the cover, in order that if the luting should give way in -any part, it may be repaired without suffering the covers (which should -be kept during the sublimation at about 320° Fahr.) to be cooled by the -removal of a large portion of the sand. - -These earthen jars may be filled to within two inches of the top, with -the dried salt gently pressed in, but not rammed close; and the fire -which has been lighted some time before, is now to be raised gradually -till the iron pots are of a pretty strong red heat all round, being so -placed by mean of flues in the furnace that the upper part may be first -heated, the bottom resting on solid brick work. - -During the first impression of the heat, a portion of the salt carrying -with it a quantity of watery vapour not separated during the drying of -the salt, will escape through the hole in the cover, which must be left -open till all the aqueous part is exhaled: this is known by bringing a -piece of cold smooth iron plate near the hole, in order to condense the -sublimate, which becoming more and more dry, at length attaches itself -firmly to the plate, in the form of a dry semi-transparent crust. - -At this time the hole is to be stopped with lute, more sand is to be put -on the cover, and the heat continued till it is judged that nearly the -whole of the muriate of ammonia is sublimed. The time requisite for this -purpose depends on the construction of the furnace, the size of the -pots, the briskness of the fire, and other circumstances only to be -learnt by experience. - -The process should be stopped before the sublimation has entirely -ceased, as the heat in some parts of the jar may be too great when it is -nearly empty, and either by volatilizing a part of the salt itself, or -elevating a portion of foreign matter from which it can never be kept -wholly free, and thus giving the cake a yellow tinge, and a scorched, -opake, crackled appearance. - -The same defects are likely to happen, when any part of the luting -having given way, is obliged to be repaired by wet lute, when the -sublimation is pretty far advanced: consequently glass vessels are -preferable, except on account of the expence, as they must always be -broken to pieces in order to get out the cake: the earthenware jars on -the contrary will serve for several sublimations, even the covers, if -well glazed, will last two operations. The sublimation being finished -and the apparatus having become sufficiently cool, the tops of the jars -are to be taken off, and the cakes of sal-ammoniac that are found -adhering to them are to be separated, and placed for a day or two in a -damp atmosphere, which softens their surface a little, and thus -facilitates the removal of any superficial impurities. Lastly, the cakes -are packed up in casks for sale. - -The excise laws have hitherto operated strongly against the -establishment of manufactories of muriate of ammonia in England. Hence -an immense quantity of sulphate of ammonia obtained from the gas light -ammoniacal liquor, is exported from this country to the continent, -solely from the extreme rigour of the excise relating to the use of -common salt, and it is only this that has hitherto prevented the -establishment of manufactories of sal-ammoniac from the ammoniacal -liquor of the gas light process upon a large scale. - -Chemical manufactories, of all others, will least bear excise, because -many of them are worked according to secret processes, which, if made -public, must pass into other countries; and the greatest part of the -profit ceases together with the export. The vexatious introduction of -excise officers into manufacturing laboratories, it is evident, puts an -end to all secrecy of operation. There are several chemical processes -which interruption will extremely injure, and others which it totally -destroys, and as on the whole they in general are of a nature in which -interference of others is most peculiarly vexatious, in all probability, -if the excise be extended to manufactures of this nature, it will -eventually put a stop to most of them, and greatly injure the revenue by -causing thereby to cease the duties which at present arise from the -exports and imports to a large amount, now depending on the chemical -trade of Great Britain. - -We have now gone through all the improvements by which the gas light -manufacture has been distinguished during the interval which has elapsed -since the publication of our former work[65] on this subject; and -perhaps the reader may be inclined to think, from the extraordinary -height to which improvement has been carried in this art, that little or -nothing more remains to be desired with regard to it. Let it be -remembered, however, that the whole art is only in its infancy. There is -yet a wide field for improvement in the construction of the apparatus. -Ingenious men may speculate from what has been done, to what remains to -be effected, which no doubt will lead to objects of the greatest -utility, and most extended national importance. - - [65] A practical treatise on gas light. - - - - -DESCRIPTION OF THE PLATES. - - - PLATE I. - - PAGE. - - Elevation of the Revolving Gas Holder at the Westminster Gas - Works 181 - - - PLATE II. - - Gas Light Apparatus at the Royal Mint. - - Fig. 1, Perpendicular Section of one of the Horizontal Rotary - Retorts with its Furnace 112 - - Fig. 2, The Purifying Apparatus 150 - - Fig. 3, The Tar Cistern 117 - - Fig. 4, The Gas Metre 214 - - The roof of the building surrounding the Gas Works is furnished - with a projecting Louver to let out the smoke. - - - PLATE III. - - Fig. 1, Represents a perspective view of a Portable Gas Metre 219 - - Fig. 2, Perpendicular Section of the Horizontal Rotary Retorts at - the Royal Mint Gas Works--at Chester--Birmingham, &c. 112 - - Fig. 3, Perpendicular Section of the Gas Holder Valve and Siphon, - or Water Reservoir 222 - - Fig. 4, Perspective View of the Governor, or Regulating Guage, - for maintaining the Flames of Gas Lamps and Burners of an uniform - intensity 225 - - Fig. 5, Plan of the Horizontal Rotary Retorts at the Royal - Mint--Chester--Bristol--Birmingham--Kidderminster, &c. 115 - - Fig. 6, Transverse Section of the Gas Metre at the Royal - Mint--Chester--Birmingham, &c. 219 - - Fig. 7, Perpendicular Section of the Gas Holder Valve 221 - - Fig. 8, Front elevation of the Gas Metre, at the Royal Mint, - shewing the registering train of Wheel Work 218 - - Fig. 9, Perpendicular Section of the Gas Holder, Governor, or - Regulating Guage, at the Bristol--Birmingham--and Chester Gas - Works 171 - - Fig. 10, Transverse Section of the Air-Box, and Lime Trough, See - purifying apparatus 152 - - Fig. 11, Perspective View of a Portable Governor or Regulating - Guage 232 - - Fig. 12, Coal Tray of Horizontal Rotary Retort 116 - - Fig. 13, A jointed swing Bracket Lamp 257 - - Fig. 14, A Mercurial Universal Joint for Pendent Gas Lamps 256 - - - PLATE IV. - - Fig. 1, Transverse Section of the Retort Ovens, at the Westminster - and City of London Gas Works, showing the mode of setting and - arranging Cylindrical Retorts 69 - - Fig. 2, Longitudinal Section of the same 69 - - - PLATE V. - - Fig. 1, Front elevation of the Retort Ovens at the Westminster and - City of London Gas Works 69 - - Fig. 2, Perpendicular Section of the Gas Holder, without Specific - Gravity Apparatus, at the Birmingham Gas Works 177 - - Fig. 3, Plan of the same 177 - - Fig. 4, Perpendicular Section of Mr. Malam’s Lime Machine 143 - - Fig. 5, Plan of the same 146 - - Fig. 6 and 7, Mouth Piece and Cover of cylindrical, - parallelopipedal and semi-cylindrical Retorts, (exhibited fig. 1, - plate IV,) drawn to a larger scale 71 - - Fig. 8, 9, 10, 11, 12, and 13, Gas Lamps and Burners 253 - - Fig. 14 and 15, Profile View and Section of Gas Mains, and mode of - connecting them 240 - - Fig. 16, 17, and 18, Perpendicular Section of the - parallelopipedal, ellipsoidal, and semi-cylindrical Retorts 53 - - Fig. 19, 20, 21, and 22, Union Joint, and circular bends for - connecting Gas Pipes 266 - - Fig. 23, Test Apparatus for certifying the proper manner of - working the Lime Machine 157 - - - PLATE VI. - - Fig. 1, Plan, showing the Fire Place and Flues, of the Horizontal - Rotary Retorts 113 - - Fig. 2, Longitudinal Section of the Collapsing Gas Holder, and - the Tank of ditto 189 - - Fig. 3, Transverse Section of the same 189 - - Fig. 4, End View of the same 189 - - Fig. 5 and 6, Horizontal plan shewing the mode of connecting the - end plates of the Collapsing Gas Holder 192 - - Fig. 7, Perpendicular Section of the Gas Holder, without specific - gravity Apparatus, at the Chester Gas Works 175 - - Fig. 8, Perspective View of the Revolving Gas Holder, at the - Westminster Gas Works 181 - - Fig. 9, Perspective View of the Reciprocating Safety Valve 196 - - Fig. 10, Plan of the Purifying Apparatus, or Lime Machine, shewing - the Air Trough of the Apparatus, with its axis and claws 152 - - Fig. 11, Sliding part of a Pendent Gas Lamp, which may be raised - or depressed 257 - - - PLATE VII. - - Exhibits an economical arrangement of a Gas Apparatus, for lighting a - town, or large districts. The central building exhibits the Retort - House. The roof is furnished with a projecting Louver to let out the - smoke. The gable ends, and one side of the building, are of - brick-work, the other side of the house is open, and supported on iron - columns. The building to the right hand side of the Retorts, is the - Purifying House, it contains the Lime Machine, page 149. The trap - door, marked A, indicates the Cistern or Reservoir for receiving the - Waste Lime. The third and smallest building in the design, serves for - an Office of the Director of the Works. The front wall is represented - as taken away, to show the position of the Gas Metre, the axis of - which drives the agitating shaft of the Lime Machine. The axis of the - Metre and the shaft of the Lime Machine, are for that purpose - connected by a strap, (page 213.) The small building-on the left hand - side of the Retort House, is a Smith’s Shop. T, shows the situation of - the Main Gas Holder Valve (page 221.) - - - - -INDEX. - - - A. - - Advantages of the art of procuring light by means of coal gas 1 - - Air box of lime machine 153 - - Ammoniacal liquor, quantity obtainable from a given quantity of - coal 303 - - Ammoniacal liquor, quantity of sulphuric acid, required for - saturating a given quantity 303 - - Ammoniacal liquor, conversion of, into carbonate of ammonia 303 - - Ammoniacal liquor, conversion of, into muriate of ammonia 303 - - Apparatus for obtaining carburetted hydrogen gas from coal tar 285 - - Apparatus for purifying coal gas 141 - - Apparatus for certifying the proper mode of working the lime - machine 157 - - Argand gas lamp 253 - - Argand gas lamp, quantity of gas consumed by different kinds 275 - - Art of procuring coal gas, theory of 33 - - - B. - - Bat’s wing gas burner 255 - - Bends, for connecting gas pipes 267 - - Burner, argand 253 - - Burner, bat’s wing 255 - - Burner, cockspur 255 - - Branch pipes 239 - - Branch pipes, dip of 243 - - Branch pipes, mode of connecting 263 - - Branch pipes, mode of proving 265 - - Branch pipes, corrosion of 260 - - - C. - - Carbonate of ammonia, preparation of, from ammoniacal liquor of - coal 303 - - Cement, for connecting gas mains 241 - - Chandelier, sliding, for burning gas 257 - - Chester gas holder, description of 175 - - Coal, analysis of, by destructive distillation 35 - - Coal, chemical constitution of 42 - - Coal, classification of 41 - - Coal, comparative facility with which different species are - decomposed 106 - - Coal, chiefly composed of bitumen only, varieties of 42 - - Coal, chiefly composed of bitumen, maximum quantity of gas - obtainable from them 43 - - Coal, containing more carbon than bitumen 45 - - Coal, containing more carbon than bitumen, maximum quantity of gas - obtainable from them 48 - - Coal, destitute of bitumen 42 - - Coal, maximum quantity of gas obtainable from them 44 - - Coal, Gloucestershire 49 - - Coal, Kilkenny 44 - - Coal, Lancashire 44 - - Coal, Newcastle 47 - - Coal, Scotch 109 - - Coal, Warwickshire 109 - - Coal, Welch Stone 48 - - Coal, Yorkshire 44 - - Coal oil 300 - - Coal oil, quantity obtainable from a given quantity of coal tar 302 - - Coal tar 298 - - Coal tar, quantity obtainable from a given quantity of coal 122 - - Coke, quantity obtained in the gas light process from a given - quantity of coal, by means of cylindrical retorts 132 - - Coke, quantity obtained by means of horizontal rotary retorts 132 - - - F. - - Flue plan of setting cast iron retorts 59 - - Flue plan, report on a series of operations, made with retorts - worked on the flue plan 61 - - Fuel, minimum quantity required for the complete decomposition of - coal, by means of cylindrical retorts 61 - - - G. - - Gas, average cost of manufacturing it upon a large scale, in - London 106 - - Gas, apparatus for lighting a town, best situation of, as far as - it regards the most economical distribution of the pipes 249 - - Gas, apparatus for lighting a town, arrangement of 319 - - Gas, apparatus for lighting a town, at the Royal Mint 112 - - Gas, burners, different kinds of 253 - - Gas, quantity of, evolved during different periods of the - distillatory process employed for decomposing coal, in - cylindrical retorts 77 - - Gas, observations on the progressive evolution of, during - different periods of the distillatory process with cylindrical - retorts 79 - - Gas flame, mode of regulating the magnitude of 234 - - Gas holder, construction of, originally employed 164 - - Gas holder, sheet iron, best adapted for it 180 - - Gas holder, sheet iron, best adapted for it, cost of 164 - - Gas holder, sheet iron, lately adopted without specific gravity - apparatus 169 - - Gas holder, at Birmingham without specific gravity apparatus 177 - - Gas holder, at Bristol without specific gravity apparatus 175 - - Gas holder, at Chester without specific gravity apparatus 175 - - Gas holder, collapsing 185 - - Gas holder, collapsing, rule for finding its capacity 195 - - Gas holder, revolving at the Westminster gas works 181 - - Gas holder, collapsing, rule for calculating its capacity 185 - - Gas holder, valve 221 - - Gas from coal tar 286 - - Gas from coal tar, average quantity obtainable from a given - quantity of tar 286 - - Gas from oil 289 - - Gas from oil, quantity obtainable from a given quantity of oil 297 - - Gas from vegetable tar 284 - - Gas from vegetable tar, average quantity obtainable from a given - quantity of tar 284 - - Gas illuminating power of 271 - - Gas lamps 253 - - Gas lamps, diameter of the pipes for supplying them with gas 261 - - Gas mains 239 - - Gas mains, mode of proving them when laid 245 - - Gas mains, observations on 247 - - Gas mains, cost of a mile, laid under ground in London 252 - - Gas mains, of pewter, lead, and tin, why unfit for distributing - gas 260 - - Gas mains, weight of different lengths, of a given bore 251 - - Gas metre, construction of 214 - - Gas metre, construction of, at the Royal Mint Gas Works 214 - - Gas metre, directions to workmen for fixing it 229 - - Gas metre, rule for calculating its power 220 - - Gas metre, at the Birmingham Gas Works, registering capacity of 220 - - Gas metre, at the Bristol Gas Works, registering capacity of 220 - - Gas metre, at the Chester Gas Works, registering capacity of 220 - - Gas pipes, directions to workmen for adapting them to the - interior of houses 258 - - Gasometer house, of sheet iron, of a given size, cost of 178 - - Gasometer, tank of cast iron, of a given size, cost of 178 - - Gasometer, tank of brick work, of a given size, cost of 178 - - Gasometer, tank of wood, of a given size, cost of 178 - - Governor, or regulating guage 261 - - Governor, its application and efficacy 171 - - Governor, directions to workmen for fixing it 229 - - - H. - - Horizontal rotary retort. (See rotary retort horizontal) 110 - - - L. - - Lamps for burning coal gas 253 - - Lamps for burning coal gas, quantity of gas consumed by different - kinds, in a given time 275 - - Lime machine originally employed, defects, and dangerous - consequences to which it gave rise 141 - - Lime machine, lately adopted 149 - - Lime machine, at Birmingham gas works 149 - - Lime machine, at Chester gas works 149 - - Lime machine, at Royal Mint gas works 150 - - Lime machine, capacity requisite for purifying a given volume of - gas in a given time 157 - - - M. - - Mains for conveying gas 245 - - Mains, average cost of a mile when laid in London 252 - - Mains, manner of proving them when laid 245 - - Mains, kind of, most economical for conveying gas 251 - - Mains, which do not supply branch pipes or lamps, observations on 250 - - Mains, faulty, how distinguished 240 - - Mercurial joint for pendent gas lamps 256 - - Muriate of ammonia, preparation of, from the ammoniacal liquor of - coal 303 - - - N. - - Newcastle coal, maximum quantity of gas obtainable from different - kinds 47 - - - O. - - Oven, for heating retorts, (See retort oven) - - Oil, from coal tar 300 - - Oil gas 289 - - Oil gas, quantity obtainable from a given quantity of whale oil 296 - - Oven plan, of setting cast iron retorts 67 - - - P. - - Pendent gas lamp 257 - - Pipes, directions to workmen for adapting them to the interior of - houses 258 - - Pitch from coal tar 302 - - Pitch, quantity obtainable from a given quantity of tar 302 - - Purifying apparatus, (See lime machine) 150 - - - Q. - - Quicklime, best method of preserving it for the purification of - coal gas 160 - - Quicklime, quantity required for purifying a given volume of coal - gas 162 - - - R. - - Reciprocating safety valve 196 - - Regulating guage, regulator, or governor 171 220 - - Regulating guage, at Birmingham Gas Works 177 - - Regulating guage, at Bristol Gas Works 177 - - Regulating guage, at Chester Gas Works 177 - - Retorts, cylindrical cast iron 52 - - Retorts, cylindrical, method of heating them by flues 59 - - Retorts, cylindrical, experiments on setting three to one fire - place 61 - - Retorts, cylindrical, experiments on setting four to one fire - place 53 - - Retorts, cylindrical, cost of erecting them 99 - - Retorts, cylindrical, best mode of working them 94 - - Retorts, cylindrical, minimum quantity of fuel required for - working them 61 - - Retorts, cylindrical, temperature best adapted for working them 94 - - Retorts, cylindrical, conical 52 - - Retorts, cylindrical, conical, comparative power of 55 - - Retorts, cylindrical, ellipsoidal 53 - - Retorts, horizontal rotary 110 - - Retorts, horizontal rotary, at the Royal Mint Gas Works 112 - - Retorts, horizontal rotary, at Birmingham 111 - - Retorts, horizontal rotary, at Chester 111 - - Retorts, horizontal rotary, at Kidderminster 111 - - Retorts, horizontal rotary, action and management of 121 - - Retorts, horizontal rotary, advantages of 124 - - Retorts, horizontal rotary, directions to workmen with regard to - working them 134 - - Retorts, parallelopipedal 52 - - Retorts, parallelopipedal, comparative power of 55 - - Retorts, parallelopipedal, best mode of working them 93 - - Retorts, semi-cylindrical 53 - - Retorts, oven, description of, at the Westminster and City of - London Gas Works 69 - - Retorts, oven, experiments on 84 - - Revolving gas holder, at the Westminster Gas Works 181 - - Revolving gas holder, rule for calculating its capacity 185 - - - S. - - Safety valve, reciprocating 196 - - Self-acting guage, (see governor) 171 - - Siphon 221 - - Sliding chandelier 257 - - South London Gas Works 69 - - Spigot and faucit pipes 241 - - Staffordshire coal 44 - - Swing bracket gas burner 257 - - - T. - - Tar, quantity obtainable from a given quantity of coal 130 - - Tar gas, quantity obtainable from a given quantity of coal tar 287 - - Tar gas, from vegetable tar 284 - - Tar, retort 285 - - Temperature for working cast iron retorts, remarks on 94 - - Test apparatus, for certifying the proper manner of working the - lime machine 157 - - Theory of the production of gas lights 39 - - Towns lighted with gas 149 - - - V. - - Valve of gas holder 221 - - Valve, hydraulic 116 - - Valve, of horizontal rotary retort 116 124 - - Valve, lime machine 156 - - Valve, reciprocating 196 - - Ventilation of rooms lighted by gas 276 - - - W. - - Water reservoir, (See Siphon) 221 - - Wheel work, registering of gas metre 218 - - - - -LONDON PRICE LIST - -Of the most essential articles employed in the manufacture and -application of Coal Gas; delivered free of expence at any Wharf between -London and Vauxhall Bridge. - - -_Cast iron Spigot and Faucit Pipes._ - - DIAMETER. THICKNESS IN THE METAL. PRICE PER YARD. - £. _s._ _d._ - 1 and a half inch 5-sixths of an inch 2 6 - 2 inches 3-eighths 3 6 - 2 and a half ditto ditto 4 0 - 3 inches 7-sixteenths 4 6 - 4 ditto half an inch 6 6 - 5 ditto ditto 9 0 - 6 ditto ditto 10 0 - 7 ditto ditto 11 0 - 8 ditto 5-eighths 12 3 - 9 ditto ditto 16 6 - 10 ditto ditto 19 6 - - -_Cast iron Flanch Pipes._ - - 1 and a half inch 3 0 - 2 inches 4 0 - 2 and a half inch 4 10 - 3 inches 5 4 - 4 ditto 7 3 - 5 ditto 9 6 - Quadrant flanch pipes 14 0 cwt. - Bend pipes of different radii, branch pipes and - accommodating pipes 13 0 cwt. - From eight to six inches 13_s._ 6_d._ from 5 to 3 - inches 14 0 - Two, and 1 and a half inch 14 6 - Siphon, water reservoir, or tar-well pipes, from 2 - to 6 inches in diameter 15 0 cwt. - Ditto, above 6 inches in diameter 14 0 - Gas holder, or hydraulic valve pipes, with boxes 15 0 - Wrought iron work and screws to ditto 0 7¹⁄₂ ℔ - Retorts of best picked iron, from second process 13 0 cwt. - Mouth pieces to ditto, ground and fitted 20 0 - Wrought iron work and screws to ditto 0 7¹⁄₂ ℔ - Connecting and stride pipes, ground 20 0 cwt. - Hydraulic cylinders 15 0 - Tapering pipes 15 0 - Outer fire doors 15 0 - Inner ditto 11 0 - Fire back, bearers, dead plates 11 0 - Top, register, and slide dampers 14 0 - Pullies, and friction sectors, turned and fitted 22 0 - Wrought iron gudgeons for ditto, turned and fitted 1 0 ℔. - One inch bolts } - Seven-eighths ditto } at 0 0 5¹⁄₂ ℔. - Three-quarters ditto } - Five-eighths 2 8 0 gross. - Half-inch 1 18 0 gross. - Tar receivers and purifying vessels 0 14 0 cwt. - Condensing pipes, and inlet and outlet pipes for - tanks 0 14 0 - Cast iron tanks put together complete, with bolts, - screws, cement, &c. 0 16 0 - Gas holders, original construction, erected - complete of sheet iron 0 60 0 - Gas holder, collapsing ditto, complete, capacity - 30,000 cubic feet 1000 0 0 - Gas holder, collapsing ditto, complete, capacity - 15,000 cubic feet 700 0 0 - Gas holder, collapsing ditto, complete, capacity - 22,000 cubic feet 800 0 0 - - -_Wrought iron Gas Tubes screwed and fitted, warranted to bear a pressure -equal to a column of water 300 feet high._ - - BORE. PENCE PER FOOT. - 1 inch 10 - 7-eighths 8 - 3-quarters 7¹⁄₂ - 5-eighths 7 - Half an inch and 3-eighths 6¹⁄₂ - - -_Copper Tubes._ - - BORE OF TUBE. PRICE PER FOOT. - £ _s._ _d._ - 3-eighths of an inch copper tubes 0 4¹⁄₂ - Half ditto ditto 0 6 - 5-eighths ditto ditto 0 9 - 3-quarters ditto ditto 0 11¹⁄₂ - 7-eighths ditto ditto 1 4 - 1 inch ditto 1 8 - 1 and a half ditto ditto 2 2 - - Union joints 3-eighths of an inch 8_s._ half an - inch 9_s._ 5-eighths of an inch 10_s._ 6_d._ - 3-quarters of an inch 0 14 0 per doz. - Union T sockets, 3-quarters of an inch 20_s._ - half inch 0 14 0 per doz. - Three-quarters of an inch main cocks 0 4 6 each - - -_Brazed sheet iron Tubes._ - - BORE OF TUBE. PRICE PER FOOT. - _s._ _d._ - 3-eighths of an inch 0 3³⁄₄ - Half an inch 0 4¹⁄₄ - 5-eighths of an inch 0 5 - 3-quarters 0 6¹⁄₂ - 1 inch 0 7¹⁄₂ - 1 and a quarter 0 10 - 1 and a half 1 3 - - £. _s._ _d._ - Ornamental gas lamp posts, and columns, fitted - complete with York lamps glazed, tube, branches, - cocks, and burners, ready for lighting £. 6 6 0 each - Or castings for ditto 13 0 cwt. - Wrought iron work for ditto 0 7¹⁄₂ ℔. - Argand burners complete, from 2_s._ 6_d._ to 5 0 each - Iron roofs for retort and gas holder houses, - erected complete, at £. 6 6 0 per square of 100 - feet, superficial measure. - - -_Cost of laying cast iron Gas mains in London. To take up the ground, to -fill in, but not to re-pave the ground, and to drive two and a half -inches of lead into the joints of the pipes._ - - DIAMETER OF MAINS. PER YARD. - _s._ _d._ - 3 inches 1 6 - 4 ditto 1 10 - 5 ditto 2 1 - 6 ditto 2 2 - 7 ditto 2 4 - 8 ditto 2 7 - 9 ditto 3 0 - 10 ditto 3 4 - - £. _s._ _d._ - Tapping the mains and laying gun barrel, or - branch pipes 0 1 0 per yrd. - Governor complete to regulate every 24 hours - 30,000 cubic feet of gas 60 0 0 - A lime machine, new construction, to purify - 30,000 cubic feet of gas every 24 hours 220 0 0 - A gas metre, to register 30,000 cubic feet of - gas every 24 hours 105 0 0 - A gas light apparatus complete, capable of - producing 48,000 cubic feet of gas every 24 - hours, costs, if erected in London 8000 0 0 - - - ESTIMATE - OF - ~A Gas Light Apparatus,~ - Capable of producing every 24 hours, a light equal to 21,330 tallow - candles, eight in the pound, burning for six hours. - - £. _s._ _d._ - - Five horizontal rotary retorts, 12 feet 6 inches in - diameter, complete for immediate use 2320 0 0 - Two lime machines, ditto ditto 536 0 0 - Two collapsing gas holders, 30,000 cubic feet capacity - each 2000 0 0 - A gas metre 200 0 0 - A governor or regulating guage 100 0 0 - Tar well 58 0 0 - Pumps 67 0 0 - Connecting pipes 265 0 0 - Condensing pipes, between the retorts, tar well, and - lime machines 219 16 0 - Retort house, with iron roof 653 19 0 - Lime machine house, with ditto ditto 230 0 0 - Workmen’s tools and sundries 430 0 0 - ---------------- - £. 7079 15 0 - -This apparatus is capable of producing every 24 hours, 66,000 cubic feet -of gas. - - -THE END. - - - C. Green, Printer, 15, Leicester Street, - Leicester Square. - - - - -_In the Press_, - -A DESCRIPTION OF THE CHEMICAL APPARATUS AND INSTRUMENTS, - -WITH FIFTEEN QUARTO COPPER PLATES, - -BY FREDRICK ACCUM. - - -WORKS - -LATELY PUBLISHED BY FREDRICK ACCUM. - - -A PRACTICAL ESSAY ON CHEMICAL RE-AGENTS OR TESTS, - -Exhibiting the general nature of Chemical Re-Agents or Tests--the -Effects which they produce upon different bodies--the Uses to which they -may be applied, and the Art of applying them successfully. - -THE SECOND EDITION, - -_Illustrated by a Series of Experiments._ _Price 9s._ - - -CHEMICAL AMUSEMENT, - -Comprising a Series of curious and instructive Experiments in Chemistry, -which are easily performed, and unattended by Danger. - -_The Fourth Edition._ _Price 9s._ - - -A PRACTICAL TREATISE ON GAS LIGHT, - -WITH SEVEN COLOURED PLATES, - -Exhibiting a summary description of the Apparatus and Machinery best -calculated for illuminating Streets, Houses, and Manufactories, with -Coal Gas; with Remarks on the general nature of this new branch of civil -economy. - -_The Fourth Edition._ _Price 12s._ - - -ELEMENTS OF CRYSTALLOGRAPHY, - -_After the Method of Haüy_, - -WITH PLATES AND GRAPHIC DESIGNS, - -Exhibiting the Forms of Crystals, their Geometrical Structure, and -general Laws, according to which the immense variety of actually -existing Crystals are produced. - -_Price 15s._ - - -A MANUAL OF ANALYTICAL MINERALOGY, - -Intended to facilitate the Practical Analysis of Minerals, by pointing -out to the Student concise directions for performing the Analysis of -Metallic Ores, Earths, and other Minerals. - -_Second Edition._ _2 Vols._ _Price 15s._ - - -A SYSTEM OF THEORETICAL AND PRACTICAL CHEMISTRY, - - -IN TWO VOLS. WITH PLATES. - -_Second Edition. Price 15s._ - - - - -_Directions to the Binder._ - - -Plate II, to face Title Page. - -Plate III, IV, V, VI, and VII, at the end of the Book. - - - - -[Illustration: _Pl. III._ - -GAS LIGHT MACHINERY, AT THE ROYAL MINT. - -_in Explanation of Plate, II._ - -_Accums, Discription of Gas Works._] - - -[Illustration: _Pl. IV._ - -_Accums, Description of Gas Works._ - -_G. H. Palmer, Del._ - -GAS WORKS. - -_Westminster Station_] - - -[Illustration: _Plate V._ - -_Accums, Description of Gas Works._ - - _Gas Holder at Birmingham - without Specific Gravity Apparatus, - capacity 30,000 Cubic Feet._ - -_W. Read, Sculp.^{t}_] - - -[Illustration: _Plate VI._ - -_Accums, Description of Gas Works._ - - _Gas Holder at Chester - Without Specific Gravity Apparatus, - Capacity 30,000 Cubic Feet._ - - _Gas Holder at Westminster, - Without Specific Gravity Apparatus, - Capacity 15,400 Cubic Feet_ - -_W. Read, Sculp.^{t}_] - - -[Illustration: _Accums, Description of Gas Works._ - -_Pl. VII._ - -GAS-WORKS. - -_Lowry, Del.^{t} & Sculp.^{t}_] - - - - - Transcriber’s Notes - - - Inconsistent, archaic and unusual language, punctuation and spelling - have been retained, except as mentioned below. The book uses a comma - for decimal point as well as for thousands separator. - - The (minor) differences in wording between the Table of Contents and - the actual text headings and the use of £ (with or without full stop - and/or space) and _l._ have not been standardised. - - Depending on the hard- and software used and their settings, not all - elements may display as intended. - - When relevant, texts have been removed from the plates and transcribed - outside the plates. - - Plate II, 'Accums’': as printed in original work. - - Page xv, entry AMMONIACAL LIQUOR: there is no separate section for - this material, but it is described in the first part of the section on - Carbonate of Ammonia on page 303. - - Page 43, 'Pont Tops': possibly Pontops. - - Page 49, 'Tramsaren, near Kidwelly': possibly Trimsaran. - - Page 79, table: the quantities given add up to 556 cubic feet. - - Page 84, 'Enclosed are the result': as printed in the source document. - - Page 86, Expenditure of Process A: the amounts given do not add up to - the total. - - Page 103/104, calculation: the numbers given do not add up to the - first sub-total. - - Page 196, example of capacity calculation: the dimensions given result - in a capacity of 22,500 cubic feet. - - Plate III, 'discription': as printed in the source document. - - - - - Changes: - - Footnotes have been moved to under the paragraph where they are - referenced. - - Tables printed over multiple pages have been re-combined into single - tables; where relevant, items such as Carried Over etc. have been - removed. The lay-out of the tables with financial analyses has been - standardised. - - Several obvious minor typographical and punctuation errors have been - corrected silently. - - Page iii: 'as its little expresses' changed to 'as its title - expresses'. - - Page x: entries for pages 80 and 81 moved to their proper place. - - Page xv: page number for entry AMMONIACAL LIQUOR changed to 303 (see - above). - - Page 42, 'principle coal mines' changed to 'principal coal mines'. - - Page 43: 'Cowpers Main' changed to 'Cowper’s Main'. - - Page 143: 'Melam' changed to 'Malam'. - - Page 189, 'a fixed rigde point' changed to 'a fixed ridge point'. - - Page 218, '10,00,000 revolutions' changed to '100,000 revolutions'. - - Page 304: 'it will turn blue litmus, paper red' changed to 'it will - turn blue litmus paper, red'. - - Page 312: 'sal-ammonia' changed to 'sal-ammoniac'. - - Index: Lines used as ditto marks and the word 'ditto' have been - replaced with the dittoed words and phrases. - - - - - -End of the Project Gutenberg EBook of Description of the Process of -Manufacturing Coal Gas, for t, by Frederick Accum - -*** END OF THIS PROJECT GUTENBERG EBOOK DESCRIPTION OF THE PROCESS *** - -***** This file should be named 63117-0.txt or 63117-0.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/6/3/1/1/63117/ - -Produced by deaurider, Harry Lamé and the Online Distributed -Proofreading Team at https://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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