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 GAS-WORKS , and the Practice of Manufacturing and 
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 LOCKWOOD & CO, 7, STATIONERS’ HALL COURT, E.C. 
 
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A TREATISE ON 
 
 GAS WORKS 
 
 AND THE PRACTICE OF MANUFACTURING AND 
 DISTRIBUTING COAL GAS 
 
 By SAMUEL HUGHES, C.E. 
 
 FOURTH EDITION , , WITH ILLUSTRATIONS 
 REVISED BY W. RICHARDS, C.E. 
 
 library I 
 
 umeit 
 
 LONDON 
 
 LOCKWOOD & CO., 7, STATIONERS’ HALL COURT 
 
 LUDGATE HILL 
 
 1871 
 
Digitized by the Internet Archive 
 in 2016 
 
 
 https://archive.org/details/constructionofgaOOhugh 
 
preface. 
 
 The engagements of Mr. Hughes having prevented 
 his making the necessary revisions for a new Edition 
 of this book, I have been entrusted with the task, and 
 m accepting it have endeavoured to make a really 
 
 practical manual of the present condition of gas manu- 
 facture. 
 
 Ihe great change which has taken place in this 
 branch of industry during the past few years, has 
 demanded considerable alteration in the work; much 
 new matter has been added, and several woodcuts 
 illustrative of the various apparatus have been intro- 
 duced; so that I trust the present Edition may be 
 found equal to the requirements of those interested 
 in the production and distribution of gas. 
 
 WILLIAM RICHARDS. 
 
 
CONI 
 
 CHAPTER I. 
 
 EARLY HISTORY OF GAS-LIGHTING. 
 
 Inflammable gas known from a very early period — Most inflammable 
 gases composed of very simple elements — Gas produced by decom- 
 position, 1. Discoveries with respect to gas and steam — Effect of 
 modern applications of science — Veneration of the ancient world for 
 burning flames, 2. Superstitions entertained on the subject — Mists 
 cleared away by modern chemistry — Notices of perpetual fires in 
 the works of Strabo and Plutarch — Greek fire-altars, 3. Writings 
 of Herodotus, Ctesias, Vitruvius, and others — Bituminous strata in 
 various parts of the world — Springs of bitumen described by 
 Herodotus, 4. Plutarch’s description of the burning fountain of 
 naphtha in Ecbatana — Use of natural gas in China arising from beds 
 of bituminous coal — Modern examples of inflammable gas issuing 
 from the earth, 5. 
 
 Mr. Shirley’s paper in the “ Philosophical Transactions” for 1667 — 
 Burning spring near Wigan in Lancashire — Dr. Hales’s experiment 
 on the distillation of coal — Sir James Lowther’s account of the in- 
 flammable gas from a coal mine at Whitehaven, 6. Experiments 
 made with this gas — Proposal by Mr. Spedding to apply this gas 
 for lighting the town of Whitehaven, 7. Dr. Clayton’s paper and 
 experiments on the distillation of coal, 8. Discoveries of Dr. 
 Watson, Bishop of Llandaff — Mr. Murdoch’s application of coal 
 gas for illumination, 9. Dr. Henry’s statement of Mr. Murdoch’s 
 application of gas, 10. M. Lebon obtained a patent in France for 
 producing gas — First public exhibition of gas-lighting, 11. First 
 application of gas in France — Mr. Winsor first acquainted with 
 gas-lighting — Mr. Winsor’ s first exhibition of gas-lighting — 
 Mr. Murdoch erected the first gas-works, 12. Mr. Murdoch’s 
 experiments described in the “Philosophical Transactions” for 
 18u8 ; also details of the mode of producing and burning gas, 13. 
 Mr. Clegg, Mr. Northern of Leeds, Mr. Pemberton of Birmingham, 
 and Mr. Accum, engage in experiments on gas-lighting, 14. First 
 works constructed by Mr. Clegg — Mr. Murdoch received Count 
 
 APPLICATION OF COAL GAS TO USEFUL PURPOSES. 
 
VI 
 
 CONTENTS. 
 
 Romford’s medal — Mr. Winsor obtains a patent in conjunction 
 with gas-lighting, 15. Mr. Winsor’s exertions to establish the first 
 gas company — Difficulties he encountered, 16. Pall Mall first 
 lighted by gas, 17. Efforts to establish the “ National Light and Heat 
 Company,” and failure, 18. Establishment of the “ Gas Light and 
 Coke Company” — First operations of the company, 19. Engage- 
 ment of Mr. Clegg as the engineer, 20. Westminster Bridge first 
 lighted by gas — Ornamental illumination — Formation of other 
 metropolitan and provincial gas companies, 21. Proposals to 
 make gas from oils, fat, and resin, 22. Mr. Lowe’s successful 
 opposition to oil gas, 23. The application of portable and com- 
 pressed gas — Failure of the first gas companies, 23. Decent im- 
 provements in the production of gas, 25. 
 
 CHAPTER II. 
 
 ON THE CHEMISTRY OP GAS LIGHTING. 
 
 Description of the production of gas during the burning of ordinary 
 lamps and candles, 26. Chemistry, organic and inorganic bodies, 
 27. The elements — compounds, 28. Analysis — decomposition, 29 
 Gases, 30. Tests, 31. Oxygen, its characteristics, 32. Method of 
 obtaining oxygen — Hydrogen, its nature, 33. Produces water 
 wherever flame exists — How to produce hydrogen gas — Nitrogen 
 a constituent of the atmosphere, 34. Experiment demonstrating 
 the existence of oxygen in the air, and separating the nitrogen there- 
 from — Carbon abundant in nature — its properties, 35. Carbon does 
 not exist alone as gas — Sulphur exists in various forms in nature, 
 36. Combination of the elements — Affinity — Chemical symbols, 37. 
 Combining proportions — Equivalents — Formula, 38. Composition 
 of coal gas — Marsh gas, 39. Olefiant gas, 40. Hydro-carbons — 
 Experiments of Dr. Fyfe, Mr. Lewis Thompson, Messrs. Faraday 
 and Coombe, 41. Carbonic oxide, 42. Impurities of coal gas — 
 Sulphuretted hydrogen, 43. Carbonic acid, 44. Ammonia, 46. 
 Bisulphide of carbon, 47. Cyanogen, 49. 
 
 CHAPTER III. 
 
 COAL USED IN GAS MAKING. 
 
 Coal generally employed for the purpose of producing gas — The origin 
 of coal, 49. The first coal mines opened in Newcastle-on-Tyne, 
 50. The earliest patent in conjunction with coal — Various descrip- 
 tions of coal — Lignite, 51. Caking coal — Splint coal — Cherry 
 coal — Cannel coal, 52. Anthracite — Analysis of coal — Fixed and 
 volatile carbon, 53. Amount of volatile matter in various coals, 54. 
 Average yield of gas and coke from a ton of Newcastle coal — Re- 
 markable deterioration of caking coal, 55. Curious phenomena 
 when coal is stored for a considerable time — Boghead cannel coal, 
 56. Table of experiments on the quantity of gas derived from coal, 
 together with its weight and specific gravity, 57. Utility of the 
 table, 61. 
 
CONTENTS. 
 
 VU 
 
 CHAPTER IY. 
 
 ON THE CARBONISATION OE COAL. 
 
 The process of carbonisation, 62. Engraving of section of hydraulic 
 main, &c., 63. Cause of pressure of the gas — Temperature of 
 furnaces — Wedgwood’s pyrometer, 64. Daniel’s pyrometer — Table 
 of the degrees of temperature corresponding with the various 
 colours, 65. Effects of various temperatures in carbonising — Method 
 of decomposing coal, and converting its volatile constituents into 
 liquid — The most suitable temperature for iron retorts, 66. The 
 injurious effect of low temperature in distilling coal — Superiority 
 of clay retorts — The charge for furnaces, 67. Coals for distillation 
 should always be dry — Fuel used in heating furnaces — Average 
 quantity of coke used as fuel — The red-hot coke from furnaces used 
 by Mr. Croll for supplying the fires, 68. Tar used as fuel for the 
 furnaces — On the mode of working retorts, 69. Double retorts, 70. 
 The formation of carbon on the interior of retorts, 72. How 
 produced and avoided — The methods of clearing off the carbon — The 
 cause of obstructions in ascension pipes, 73. 
 
 CHAPTER Y. 
 
 SITES MOST APPROPRIATE FOR GAS-W ORKS. 
 
 Choice of site for gas-works — Railway communication very advanta- 
 geous — Great Central Company’s works at Bow, 74. Canal com- 
 munication — Position of works relative to the district to be sup- 
 plied, 75. Pressure of gas, 76. Plan of works — Knowledge of the 
 nature of ground essential previously to deciding the mode of 
 constructing works — Rules to be observed in planning works, 77. 
 Engravings of plan and section of works by Mr. Penny, 78, 79. 
 Magnitude of works described — Capital required for gas-works, 
 estimated according to population — Average consumption of gas per 
 head, 81. 
 
 CHAPTER VI. 
 
 ON THE RETORT-HOUSE AND BUILDINGS. 
 
 Retort-houses, how constructed — The coke- vault, 82. Settings of re- 
 torts — Single settings — Double settings, 83. Importance of the dimen- 
 sions of retort-house being sufficiently ample — Cost of retort-house, 
 84. Precautions necessary in the construction of retort settings — 
 Ventilating shaft, 86. Coal and coke store — Purifying house — 
 Engine, boiler, and exhauster house, 87. Station meter and governor 
 house — Chimney or stack — The cause of draught or current, 88. 
 Chimney at Edinburgh Gas Company, 89. Prices of chimney 
 stacks, 90. 
 
Vlil 
 
 CONTENTS. 
 
 CHAPTER VII. 
 
 ON THE RETORTS USED IN GAS-MAKING. 
 
 The earliest experiments of Mr. Murdock — Progressive alterations 
 made in the settings of retorts, 91. Mr. Brunton’splan of setting, 
 92. Mr. Lowe’s reciprocating retorts — Mr. Clegg’s web retort — The 
 retorts generally employed in the manufacture of gas, 93. The 
 mouthpiece, 94. Engravings of section, side and front elevation 
 of mouthpiece — Engravings of plan and side view of mouthpiece 
 attached to retort, 94 — 96. Engravings of mode of attaching door 
 to mouthpiece, 97. Wrought- iron lids preferable to cast iron — Iron 
 retorts — Their disadvantages, 98. Their durability increased when 
 in separate ovens, 99. Clay retorts — Mr. Winsor’s patent — Mr. 
 Grafton’s patents — The first clay retorts constructed by Mr. Grafton, 
 100. Engraving of section of Mr. Grafton’s brick retort — Clay 
 retorts used in Scotland previously to being employed in England — 
 Clay retorts first employed in London on a large scale by Mr. Croll 
 — Patent obtained bj r Mr. Cowen for the construction of clay re- 
 torts, 101. Gradual improvement in the manufacture of clay 
 retorts — The advantages of clay retorts — Arguments formerly used 
 against clay retorts, 102. Necessity of having an exhauster wher- 
 ever clay retorts are used, 103. The form of retort used generally in 
 Scotland — Those used in England and the Continent — Retorts used 
 at the Imperial Company’s Works, 104. Engraving of end elevation 
 of clay retort, 105. Engraving of side view of mouthpiece attached 
 to retort — Retorts sometimes cracked by the workmen, 106. Small 
 leakages in clay retorts stopped by the gas — Method of attaching 
 the mouthpieces to retorts, 107. Recipes for making iron cement 
 for joints of pipes, 108. 
 
 CHAPTER VIII. 
 
 ON RETORT SETTINGS. 
 
 Retort- setting explained — Precautions necessary in setting retorts, 109. 
 Form of furnace — Mr. Croll’s furnace, 110. On setting clay retorts, 
 111. Engravings of section and longitudinal section of settings at 
 Imperial Company’s Works, 112, 113. Diversity of opinion as to 
 the best mode of setting — Price of settings, 114. Section of setting 
 of seven retorts at the Commercial Company’s Works, 115. Cost 
 of repairs — Iron retort settings — Various forms adopted in the 
 mode of construction — Only useful in very small works, 116. En- 
 graving of section of a setting of three iron retorts, 117. Engraving 
 of longitudinal section of same, 118. Best description of bricks for 
 retort furnaces — How to prevent the radiation of heat, 119. 
 
 CHAPTER IX. 
 
 METHOD OF COMBINING CLAY AND IRON RETORTS. 
 
 The combination of clay and iron retorts first patented by Messrs. 
 Kirkham and Lowe, 119. The system perfected and carried practi- 
 
CONTENTS. 
 
 IX 
 
 cally into operation by Mr. Croll, 120. Observations on the system of 
 combining clay and iron retorts, 121. Engravings representing the 
 application of the principle on the smallest scale, 120. Engravings 
 representing other modifications, 122, 123 — Engravings represent- 
 ing settings for large works, as practised by Mr. Croll, 124 — 127. 
 Advantages of combination setting — The application of tar as fuel, 
 129. 
 
 CHAPTER X. 
 
 THE HYDRAULIC MAIN. 
 
 Serves the purpose of hydraulic valve for each retort — Mode of con- 
 struction described, 129. Engravings of section, end elevation, and 
 part of hydraulic main in plan, as constructed of wr ought-iron, 130, 
 
 131. Cast-iron mains used — The action of hydraulic mains explained, 
 
 132. Mode of attaching the gas main to hydraulic — Valves, 134. 
 
 Hydraulic and slide or surface valve — The action of the hydraulic 
 valve explained — Engravings of hydraulic valves, 135. Slide valves 
 described, 137. Engravings of sections of slide valves — Mr. Lowe’s 
 bladder valve, 138. Furnace door, ash-pan, sight-boxes, and buck- 
 staves, 139. ' 
 
 CHAPTER XI. 
 
 ON THE PURIFICATION OF GAS. 
 
 On purification generally — Gas formerly used without purification — 
 Observations on the various means of purifying gas, 141. The 
 condenser, horizontal and vertical, 142. Engravings of vertical 
 condenser, 143. Annular pipe condenser — Comparison between con- 
 densation occurring by radiation and by contact with water, 144. 
 Table illustrative of the variation — Excess of condensation causes 
 the deposit of naphthaline in the mains, 14.5. Evidence and estimate 
 of Mr. Croll relating to the cost price of condensers for the Great 
 Central Company’s works — Mr. Barlow’s estimate of the cost of 
 condensers — Area necessary for condensers, 146. On the tar and 
 ammoniacal liquor tank — Its object — The mode of construction 
 generally adopted — Seal pipe described, 147. Often in use in several 
 parts of a gas-works — Capacity of tar- tank, 148. Selling prico 
 of tar — Wash vessel described — Engravings of the apparatus, 149. 
 Gas injured by washing — Washer seldom employed at the present 
 time — The scrubber, or coke-condenser, described, 152. Sometimes 
 employed without water — Ammoniacal liquor very generally em- 
 ployed in the scrubber — Purification by wet lime — Method of pre- 
 paring the lime for the purpose, 153. The purifier described, 154. 
 Engraving of the apparatus, 155. Wet lime superior to other pro- 
 cesses of purification — Advantages of dry lime purification, 156. The 
 purifiers described, 157. The central hydraulic valve invented by 
 Mr. John Malam, 158. Engravings of plan and elevation of puri- 
 fiers, 160, 161. Modification of the hydraulic valve as a slide-valve, 
 162. On the quality of lime for purifying gas, 163. Mr. Croll’s 
 and Mr. Barlow’s estimates of the expense of purifying gas, 166. 
 
X 
 
 CONTENTS. 
 
 Oxide of iron purification patented by Mr. Croll — The system of 
 spontaneous revivification patented by Mr. Laming in France, and 
 afterwards patented by Mr. Hills, 167. Method of working the 
 oxide of iron, 168. Air has been proposed to be exhausted through 
 the purifiers, 169. 
 
 CHAPTER XII. 
 
 VARIOUS MODES OE PURIFYING GAS. 
 
 The earliest methods attempted to purify gas — Ammonia formerly 
 obtained from Egypt, 169. Mr. Croll’ s process of separating am- 
 monia from gas, 170. Description of purifier, with engravings, 171. 
 Method of applying the system, 172. Mr. Croll’ s method of puri- 
 fying by means of neutral salts, 174. Mr. Laming’s process of 
 purification, 175. The Rev. Mr. Bowditch’s system of purifica- 
 tion, 177. 
 
 CHAPTER XIII. 
 
 THE GASHOLDER. 
 
 The gasholder described, 178. Cast-iron tanks, 180. Specification of 
 cast-iron tanks, 181. A method of constructing tanks adopted by 
 Mr. G. W. Stevenson, 182. Annular or ring tanks, 183. Brick 
 tanks, where applicable — Dimensions of tanks, 184. Puddle employed 
 in construction — Tanks often made of stone, 185. Specification and 
 estimated cost of brick tank, 186. Specification of Imperial Com- 
 pany’s tank at Pancras Station, 188. The holder, how constructed, 
 191. Engraving of holder, 192. Means of calculating weight or 
 pressure, 194. Prices of various holders, 195. Specification of a 
 single-lift gasholder, 196. Specification of apparatus for gas-works, 
 198. Specification of holder at Pancras Station, 200. Telescopic 
 gasholders, how constructed, 203. Essential where space is limited, 
 204. Evils arising from telescopic gasholders — Imperial large holder 
 at Hackney — Specification of tank and gasholder, 205. Gasholders 
 as formerly constructed, 210. 
 
 CHAPTER XIV. 
 
 ON THE EXHAUSTER. 
 
 Composition of gas — Carbon from gas may be obtained in solid state, 
 212. Mr. John Grafton’s experiments — The earliest machine for 
 exhausting gas, 213. Various kinds of exhausters, Beal’s, Jones’s, 
 Methvin’s, Anderson’s, 214. The loss of light by admixture of air 
 or carbonic acid with gas — Meter formerly used as a motive power 
 — Gas engine, 215. 
 
 CHAPTER XV. 
 
 ON GAS-METERS. 
 
 First meter made by Mr. Clegg — Improved meter by Mr. Malam, 216. 
 Sir William Congreve’s hour meter — The kinds of meters in use. 
 
CONTENTS. 
 
 X] 
 
 217- The wet meter illustrated, 219. Section of meter, 220. Side 
 view of meter, 222. Front view of meter, 223. Contingencies in 
 the measurement — The attention of parliament called, 224. Com- 
 pensating meter — Sanders and Donovan’s meter, 225. Station 
 meter, 227. Dry meter^ 229. First record of dry meter — Defries’ 
 meter — Croll and Richards’ meter, 230. Compared to steam engine, 
 232. 
 
 CHAPTER XYI. 
 
 ON LAYING MAINS AND SERVICES. 
 
 Mains and services described — First mains laid by New River Com- 
 pany — Brick conduits, earthenware and glass pipes, proposed for 
 the transmission of gas — Chameroy pipes, 233. The action of 
 exosmose and endosmose described, and signification of terms, 234. 
 Mains should be tested by hydraulic pressure — Method of making 
 joints of pipes, 235. Mr. Clegg’s and Mr. Wicksted’s methods, 
 236. Pipes having their ends turned and so fitted — Large mains of 
 New River Company, how laid — To determine size of mains, 237. 
 Table of the discharge of gas per hour, through various size mains, 
 at various pressures, 238. Manner of applying table — Map of dis- 
 trict indispensable, 241. M^ains laid generally in centre of street — 
 Syphons, their object, and how constructed, 243. Condensation of gas 
 — Leakage in gas mains — Method of preserving cast-iron pipes, 244. 
 Pressure necessary under various circumstances for the proper supply 
 of a district — How to discover the point where a main is obstructed, 
 245. Table of the weight and cost of cast-iron main per yard — 
 Average price for laying, mains, 247. Services described — In 
 England are generally of gun -barrel — On the Continent services are 
 usually of lead pipe — Obstructions of services cleared by Hulett’s 
 apparatus, 248. Galvanised gun-barrel often very advantageous 
 for services — Leakage of mains — Various estimates of amount of 
 loss by leakage — Mr. Croll’ s evidence 249. Quantity of atmospheric 
 air discovered by Professor Graham to be intermixed with gas — 
 Necessity for changing mains when too small for district, 250. 
 Various incidental losses, often considered to arise from leakage, 251. 
 
 CHAPTER XVII. 
 
 ON APPARATUS FOR INDICATING AND RECORDING PRESSURE. 
 
 Pressure gauge, how constructed — Necessity of instrument to indicate 
 pressure, 252. Causes of excessive pressure — Mercury pressure 
 gauge, 253. The pressure indicator, how constructed — Its action 
 described, 254. Registering pressure gauge — Engraving of instru- 
 ment, 255. Registering papers to be preserved as records, 256. 
 Exhauster indicator, 257. 
 
 CHAPTER XVIII. 
 
 THE GOVERNOR AND REGULATOR. 
 
 Governor described, 257. Engraving of instrument, 258. Wright’s 
 governor — Governor absolutely necessary in every works — Gover- 
 
XI] 
 
 CONTENTS. 
 
 nors sometimes placed on mains to regulate the pressure of gas, 259. 
 Dry governor used by Mr. Stevenson of Halifax — Regulator — Used 
 for private houses and street lamps — Hulett’s mercurial regu- 
 lator, 260. 
 
 CHAPTER XIX. 
 
 EXPERIMENTS ON COAL GAS. 
 
 Gas affected by various causes — Effects of temperature on gas, 261. 
 Effects illustrated by experiment — Barometric pressure — Barometer 
 described, 262. The variations of increase or decrease of baro- 
 metric pressure — Examples of the necessity of corrections — Moisture 
 in gas — Specific gravity of gas, 263. On weighing gas — Various 
 methods of conducting the operation, 264. Wright’s balloon for 
 ascertaining the specific gravity — Wright’s directions, 265. Table 
 for corrections of temperature and pressure of gas, 267. Cor- 
 rections for moisture in gas — Table of aqueous vapour existing 
 in gas under various temperatures, 270. Methods of drying gas, 
 272. On the bromine and chlorine tests, 273. Mode of operating, 
 274. Process under some conditions not satisfactory — On the com- 
 parison of gases by means of the photometer, 275. The first form 
 of photometer — Bunsen’s photometer, 276. Manufacturers of 
 photometers, 277. Engravings of photometers, 278, 279. Table of 
 the distances for scale of instrument — To ascertain the weights of 
 gas produced from coal, 281. Comparison of the specific gravity of 
 gas with number of candles — Tests for ascertaining the purity of 
 gas, 282. Tests for sulphuretted hydrogen, ammonia, and carbonic 
 acid — Instrument for detecting the presence of the sulphuret of 
 carbon in gas, 283. Dr. Letheby’s instrument for determining the 
 amount of sulphur in gas, 285. 
 
 CHAPTER XX. 
 
 ON THE MODE OF BURNING GAS. 
 
 Theory of the combustion of gas — Various effects of excess or defi- 
 ciency of air and pressure considered — Under certain conditions 
 gas gives no light, 286. Loss of light by admixture of air with gas, 
 according to Dr. Letheby — Effects of excess of pressure on the 
 light given from gas, 287. Table of light yielded by various 
 descriptions of gas — Cause of the variation, 288. Best results 
 obtained when gas issues from burner at low pressure — For poor 
 gas the holes of burners are required to be large — For rich gas 
 holes of burners should be small, according to the quality of gas— 
 Variation of light obtained by argand and other burners under 
 different circumstances, 289. All burners require to be made 
 expressly, according to the quality of gas they are destined to 
 consume— The mode of determining the illuminating power of gas 
 according to the Act of Parliament prejudicial to gases of superior 
 quality — Suggestions for adopting a standard of illuminating power 
 — For poor gases the argand considered the most suitable — For rich 
 gas the fishtail is preferable, 290. Carburisation of gas— First 
 
CONTENTS. 
 
 Xlll 
 
 patented by Mr. Lowe — The system lately revived — Difficulties 
 in the carburisation of coal gas — Experiments on the evaporation of 
 liquid hydrocarbons — Mixing atmospheric air with vapours so as 
 to give light, 292. Firms established for carburising gas — The 
 process tried in the lamps of the City of London, and renounced, 
 293. 
 
 CHAPTER XXI. 
 
 RESIDUAL PRODUCTS FROM COAL. 
 
 The coke, fuel for household and other purposes — Breeze used in 
 brick-making ; also, when mixed with tar, producing an artificial 
 coal, 294. Tar, the various attempts to distil this for producing 
 gas — The products from tar, 295 — Pitch, a substitute for asphalte, 
 and good coke, produced from tar — Ammonia, how formed into 
 sulphate — Used as a purifying agent — Volatile alkali, and other 
 compounds of ammonia, produced from the residue of gas- 
 works — Waste lime from purifiers, 296. 
 
 CHAPTER XXII. 
 
 EXPLOSIONS OF GAS. 
 
 First fears of explosions — Gas unmixed with air not explosive, 297. 
 
 . Safety of gas-lighting — Mixture to be explosive, 298. Accidents 
 which have occurred, and cause of them — Explosion of station 
 meters, 299. Sheet-iron valve — Explosive compounds of gas not 
 explosive when under pressure — Some experiments on explosions, 
 300. Precautions necessary where escapes of gas exist — Meters 
 sometimes mysteriously destroyed by explosion — Causes of many 
 explosions which have taken place — Mains break in an unaccoun- 
 table manner, 302. Danger of placing mains in subways — Common 
 error, that gasholders, when charged, are explosive, 303. Valves 
 on the exterior of large buildings always of utility, 304. 
 
 CHAPTER XXIII 
 
 ON WATER GAS, OR THE HYDROCARBON PROCESS OF GAS-MAKING. 
 
 On water gas — Hydrogen produced from water capable of heating 
 apparatus, 304. Hydrogen intermixed with the vapours of volatile 
 hydrocarbonaceous liquids capable of producing light — Patents 
 obtained for the process — Sanguine expectations of its success, 305. 
 Trials on extensive scale made at the Manchester and other gas 
 companies’ works — Causes of failure, 306. Hydrogen gas employed 
 by M. Gillard to heat platinum wire, and so produce light, 308. 
 
 CHAPTER XXIV. 
 
 ON THE RATING OF GAS-WORKS IN PAROCHIAL ASSESSMENTS. 
 
 Great difference of opinion on the subject of rating — General principle 
 of rating now established— Objections of public companies to the 
 
XIV 
 
 CONTENTS. 
 
 present mode of rating, 308. General views applicable to the rating 
 of joint-stock companies — Rateable value of the London and Bir- 
 mingham Railway — Comparison with rateable value of buildings 
 representing the same amount of capital, 309. First determinations 
 to be made with respect to rating — Consideration of the law laid 
 down in the Parochial Assessment Act — Quotation from the Act — 
 Determination of rent for which gas-works would let from year to 
 year — Basis of groundwork for ascertaining this, 310. Conside- 
 ration of the argument that joint-stock companies are rated on 
 their profits — Amount of profit must be known before rent can be 
 determined in cases where the owner holds the property in his own 
 hands, 311. Mode of arriving at the profits of large joint-stock 
 companies — Arbitrary allowances for time, superintendence, interest 
 of capital, &c., 312. Principle of estimating these — Method usually 
 pursued on the part of gas companies — Summary of arbitrary 
 allowances claimed — Method pursued by advocates for the parishes 
 — Disputed allowances for salaries, interest, &c. — Statutable allow- 
 ances, 313. Repair and restoration of buildings, insurances, &c. — 
 Claims on the part of gas companies — Opposite views contended for 
 on the part of parishes — Reproduction of the rolling stock and 
 permanent way on railways — Depreciation fund set aside by some 
 railway companies, 314. Decisions at quarter sessions in rating 
 cases — Arbitrary allowances for reproduction — Proposed mode of 
 estimating costs of reproduction — Example of proposed method of 
 calculation — Estimate of allowance for reproduction of an object 
 whose duration is assumed at thirty years — Allowance where the 
 duration is assumed at various other terms of years, 315. Mr. Lee’s 
 estimate of rateable value made in the appeal case against the rate 
 in the parish of Greenwich — Detailed estimate of arbitrary deduc- 
 tions and statutable deductions — Estimate for reproducing trade 
 fixtures, mains, &c., 316. Method of estimating pursued by the 
 valuers for the parish, 317. Mr. Penfold’ s estimate of net rateable 
 value of the Phoenix Company’s works — Comparison of Mr. Pen- 
 fold’s and Mr. Lee’s rateable value — Case of the British Gas 
 Company and the parish of Ratcliff — Mr. Lee’s valuation in detail, 
 318. Valuation by the author on the part of the parish — Pro- 
 duction account — Residual products — Cost of distribution — Statu- 
 table allowances, &c., 320. Detailed estimate of gross revenue — 
 Detailed estimate of the labour of manufacturing — Detailed estimate 
 of wear and tear of etorts, 321. Detailed estimate of residual pro- 
 ducts — Detailed estimate of expenses of distribution, 322. Detailed 
 estimate of statutable allowances — Detailed estimate of capital re- 
 quired by tenant, 323. 
 
 DIVISION OF TILE NET RATEABLE VALUE BETWEEN THE SEVERAL 
 PARISHES. 
 
 Great variety of opinion existing on this subject — Judgments of the 
 Court of Queen’s Bench — Principle of dividing rateable value in 
 proportion to receipts — Principle of dividing in proportion to 
 mileage of line — Injustice of this division — Principle of divid- 
 ing rateable value according to the quantity of apparatus in each 
 parish, 324. Lord Denman’s judgment in the case of the Queen v. 
 
CONTENTS. 
 
 XV 
 
 the Cambridge Gas-Light Company — Consideration of this mode of 
 division in the case of railways — Application of the principle to 
 the rating of gas-works, 325. Mode of dividing the rateable value 
 between the works and the mains — Cases in which gas-works have 
 more than one manufacturing station — Division of rateable value 
 amongst the mains — Principle of dividing according to the square 
 yards of ground occupied by the mains in each parish — Injus- 
 tice of this mode of division, 326. Principle of dividing according 
 to the cubic yards of main in each parish — Unfairness of this mode 
 of division — Proposed mode of dividing the rateable value amongst 
 the mains — Proportion to be used for ascertaining value in each 
 separate parish, 327. Proposed annual assessment of railways, 
 canals, gas-works, &c., by a public officer to be appointed for the 
 purpose, 328. 
 

 
 
MANUFACTURE AND DISTRIBUTION 
 OF COAL GAS. 
 
 CHAPTER I. 
 
 EARLY HISTORY OF GAS-LIGHTING. 
 
 The discovery and earliest observation of elastic aeriform 
 fluids, capable of being inflamed and of imparting light and 
 heat, must undoubtedly have been of great antiquity ; inas- 
 much as many ancient writings contain notices of inflammable 
 vapours springing from fissures and cavities in the earth. It 
 is evident, therefore, that gas being a natural production, no 
 such human individual as its discoverer or inventor ever 
 existed. Modern chemistry demonstrates that inflammable 
 gases, whether arising naturally from springs, or produced 
 artificially by destructive distillation or otherwise, are com- 
 posed of very simple elements, and present a remarkable 
 analogy to the common carburetted hydrogen, which is the 
 gas chiefly burnt in our street lamps and houses at the 
 present day. 
 
 Inflammable gas may be truly said to be as old as the 
 creation of organic matter, for wherever animal or vegetable 
 substances have existed, by the immutable laws of nature 
 they have been subject to decomposition ; and wherever de- 
 composition has taken place, a variety of gases have been 
 produced, some of them inflammable, and others not so. 
 Whether the decomposition be that caused by the slow 
 
 B 
 
2 
 
 EARLY HISTORY OF 
 
 combustion of decay, or the more rapid process caused by 
 the application of sensible heat, the effect is the same — the 
 gases are equally produced in the two cases. 
 
 Gas may with truth be called a more natural production 
 than steam, although the latter has existed from the first 
 creation of water, and in its palpable state, as proceeding 
 from boiling water, must have been observed in all ages, 
 although without any views of its present application having 
 been conceived. 
 
 The discoveries of man with respect to gas and steam 
 ought rather to be called applications ; they are conquests 
 over the elements, and the subjugation of great powers in 
 nature to his use and convenience. So it is with nearly all 
 great inventions, in which we find one power of nature after 
 another chained, confined, bound down, stored, and then let 
 loose when required, and made to work machines, to propel 
 ships across the ocean, to supply the place of human labour 
 itself in a thousand variety of ways, — nay, to pass far 
 beyond the bounds of human labour, and effect that, by a 
 single effort, which the manual strength of a world coula 
 scarcely accomplish. 
 
 If such astonishing applications of steam and gas had 
 been made in the days of ancient Greece, what magnificent, 
 all-expressive, world - astounding names would have been 
 found to convey their meaning: instead of such contemptible 
 little monosyllables as gas and steam , one might have heard of 
 the soul of coal and the spirit of water, with some superlative 
 adjective to stamp the vast importance of each. In such 
 an age these wonderful conquests would have thrown all 
 meaner efforts into the shade ; for them, perhaps, would 
 poetry have strung its harp, and the grandest epic pro- 
 ductions of genius might have commemorated the victory 
 of man over the inanimate matter of nature, instead of 
 dedicating her loftiest songs to the art of war. 
 
 The avidity with which the early nations seized on all 
 natural phenomena, and all exhibitions of great natural 
 powers, is evident from the veneration paid to the burning 
 flames which issued forth from fissures and cavities in the 
 earth where probably lakes of petroleum existed, or in 
 
GAS-LIGHTING. 
 
 3 
 
 the neighbourhood of coal or bituminous schists. Some 
 of the earliest nations have considered fire as a type of 
 divinity ; and we can scarcely wonder at the feelings of 
 veneration and superstition occasioned by mysterious out- 
 bursts of flame, whose origin appeared utterly incompre- 
 hensible. Hence Superstition erected her altars over such 
 flames, and claimed the interference of the Gods to sustain 
 the perpetual miracle. But all that had been observed with 
 reference to inflammable vapours in ancient times was very 
 far indeed from approaching to anything like a useful pur- 
 pose. Far from leading to any attempt to collect and use 
 these vapours, their very nature and composition were un- 
 known, and the most mistaken ideas prevailed as to their 
 real elements. It was not till modern chemistry had exploded 
 volumes of ancient dogmas, — had traced the so-called elements 
 to far simpler forms, — aqd had divulged the laws according to 
 which elements are combined in order to constitute all forms 
 of matter, — it was not till then that it began to be seen that 
 the inflammable vapour of coal, wood, oils, and other fatty 
 substances, was analogous with the marsh gas which arises in 
 bubbles from the decomposition of vegetables under water ; 
 that it was of a similar nature to the fatal dancing “ Will-o’- 
 the-Wisp,” which on the wild moor or bog has lighted many 
 a traveller to destruction ; finally, that it resembled the gas 
 which arises from the decomposition of water, however pro- 
 duced ; and, in fact, that water, the greatest antagonist and 
 extinguisher of flame, was itself composed of the most in- 
 flammable substance in nature, namely, hydrogen gas ; while 
 oxygen, the other element of water, is the greatest known 
 supporter of combustion. 
 
 Many opinions have been hazarded to account for the 
 almost perpetual fires which were kept burning on the 
 ancient altars. Strabo and Plutarch mention these fires, 
 which they describe as constantly burning, to which they 
 add, that they are lighted by invisible means. This seems 
 to involve a contradiction ; for if they were always burning 
 they could not require lighting. 
 
 The altar in the Temple of iEgina may be taken as an 
 example of most of the ancient Greek fire -altars as exhibited 
 B 2 
 
4 
 
 EARLY HISTORY 0* 
 
 in t lie temples. Hero a round hole, about 13 inches in 
 diameter, is observed in a block of stone. This round orifice 
 opens into a square hole, which passes down through solid 
 stone to a depth of several feet. The lower end of the 
 square hole communicates with a cavity in which Mr. Dod- 
 well supposes a fire to have been constantly kept burning, 
 so that the flame did not appear above the surface of the 
 circular opening. He says nothing more would be necessary 
 than to pour oil into the opening, when the flames would 
 immediately burst forth, and appear to have a miraculous 
 origin. 
 
 The writings of Herodotus, Otesias, and Vitruvius, men- 
 tion the bituminous wells of Zakunthus, the modern island 
 of Zante. HClian notices springs near Apollonia ; and 
 Plutarch, in his Life of Alexander, mentions the fountain of 
 naphtha with fire issuing from the earth in the territory of 
 Ecbatana in Media (the modern Hamadan).* 
 
 The Babylonian bitumen, used for cementing masonry, 
 was obtained from the district which now forms the pashalic 
 of Bagdad. Bituminous strata also exist in Switzerland, 
 Germany, France, in the papal territory, in Great Britain, 
 Ireland, Cuba, and other parts of the world. 
 
 The springs described by Herodotus are not now worked ; 
 but their place is defined by the remains of a circular wall 
 about 70 feet in diameter, within which the space is nearly 
 filled up with earth. The opening from which the bitumen 
 was extracted in his day is described as communicating with 
 the sea, which, in calm weather, is tinged with the iridescent 
 colours of the bitumen as it rises up to the surface of the 
 water. 
 
 The bitumen is now drawn from small wells about 5 feet 
 diameter and 3 or 4 feet deep. This mineral was much used 
 by the ancients, as not only suitable for mortar, but also for 
 cementing reeds together, and forming floors and ceilings. 
 
 The superstitions of eastern countries have always identi- 
 fied fire with the loftiest attributes of Divinity, and even with 
 Divinity itself — while traces of fire-worship are said to exist 
 
 * Dodwell’s “ Classical and Topographical Tour through Greece.’* 
 London, 1819. 
 
GAS-LIGHTING. 
 
 5 
 
 even at the present day. In Plutarch’s Life of Aristides 
 there is a passage marking the superstitious reverence which 
 the fire of their celebrated altars enjoyed, where the conquer- 
 ing Greeks under Pausanias are directed by the oracle of 
 Delphi to build an altar to Jupiter the Deliverer, but not to 
 offer, any sacrifice on it till they had extinguished all the fires 
 in the country, because it had been polluted by the barbarians 
 (the Persians), and supplied themselves with pure fire from 
 the altar at Delphi. In consequence of this the Grecian 
 generals went all over the country and caused all the fires to 
 be put out.* 
 
 The Chinese are said to use to this day, for economical 
 purposes, the gas which escapes spontaneously from beds of 
 bituminous coal. Within 30 miles of Pekin is a coal-field 
 having beds of salt associated with the coal, and streams of 
 gas rising naturally from the coal are conveyed to the salt- 
 works by means of bamboo tubes, and there used for the 
 boiling and evaporation of the salt. Other pipes convey the 
 gas intended for lighting the streets and houses.f 
 
 There are many other instances at the present day where 
 inflammable gases issue from the surface of the earth : this is 
 the case at several places in the Apennines, particularly near 
 Pietra Mala, on the road from Bologna to Florence. A 
 similar case occurs in a mountain of Lycia, near the shore 
 of the Gulf of Adalia in Asia Minor. Most of these phe- 
 nomena no doubt arise from coal or other bituminous sub- 
 
 * Extract from Plutarch, relative to the fountain of naphtha in Ecbatana, 
 or Hamadan. Alexander “ traversed all the province of Babylon, which 
 immediately made its submission ; and in the district of Ecbatana he was 
 particularly struck with a gulf of fire, which streamed continually, as from 
 an inexhaustible force. He admired also a flood of naphtha not far from the 
 gulf, which flowed in such abundance that it formed a lake. The naphtha 
 in many respects resembles the bitumen, but it is much more inflammable. 
 Before any fire touches it, it catches light from a flame at some distance, and 
 often kindles all the intermediate air. The barbarians, to show the king its 
 force and the subtilty of its nature, scattered some drops of it in the street 
 which led to his lodgings ; and standing at one end, they applied their torches 
 to some of the first drops ; for it was night. The flame communicated itself 
 swifter than thought, and the street was instantaneously all on fire.” — “ Life 
 of Alexander,” book v. p. 152, Langhorne’s translation. 1832. 
 
 t R. C. Taylor, on the Coal-fields of China, in the Journal of the Franklin 
 Institute. A similar instance occurs in the village of Fredonia, N.Y., where 
 the inflammable gas issues from a small stream, called Canada Way, over 
 which a gasometer is erected for collecting it. — Brewster’s Journal, 1830. 
 
6 
 
 APPLICATION OF COAL GAS 
 
 stances, which by earthquake or like means have been buried 
 at such a depth as to be distilled by the heat from the interior 
 of our globe, so that the gas is expelled, and escapes through 
 the fissures of the earth. 
 
 APPLICATION OF COAL GAS TO USEFUL PURPOSES. 
 
 We find among the “ Philosophical Transactions ” of 1667, 
 a paper by Mr. Shirley, describing a spring arising in the 
 coal district of Wigan in Lancashire, and which was supposed 
 at the time to be a burning spring, because the vapour on the 
 surface of it could be inflamed. Mr. Shirley pointed out that 
 it was not the water which burnt, but the gas by which it was 
 accompanied ; and he traced its origin to the beds of coal 
 which abound in that part of the country where the spring 
 broke out. 
 
 Although these observations of Mr. Shirley referred the 
 origin of the burning spring to the right cause, and clearly 
 pointed to the possibility of procuring the same kind of gas 
 by the combustion of coal, the subject appears to have re- 
 ceived no particular attention at the time, and it was not till 
 many years had elapsed that we find another observer prompted 
 by this very same spring to institute experiments of a prac- 
 tical nature on the distillation of coal. 
 
 Probably the first authentic record of an experiment on 
 the distillation of coal, appears in Dr. Hales’ work on “ Vege- 
 table Statics,’’ published in 1726, where he states that from 
 the distillation of 158 grains of Newcastle coal he obtained 
 180 cubic inches of air (or gas), which weighed 51 grains, 
 being nearly one-third of the whole. This result, which is 
 rather more than 8,500 cubic feet per ton, agrees very nearly 
 with the production of gas actually realised from Newcastle 
 coal at the present day. 
 
 A few years afterwards, namely, in 1733, we find in the 
 “ Transactions of the Royal Society ” a communication from 
 Sir James Lowther, on the inflammable air issuing from the 
 shaft of a coal mine near Whitehaven. The workmen were 
 surprised on sinking to the depth of 42 fathoms to find a rush 
 of air taking place, which caught fire from the flame of a 
 
TO USEFUL PURPOSES. 
 
 7 
 
 candle and burnt with great intensity, making a blaze about 
 3 feet diameter and 6 feet high. Several experiments were 
 made on this flame by the steward and others, who successively 
 caused it to be extinguished by beating it down and smother- 
 ing it with the colliers’ hats and again lighting it. At length 
 the heat communicated by the flame was found to be very 
 inconvenient, as it warmed the pit to a high degree, and it 
 was necessary to have recourse to water in order to extinguish 
 it. After this the gas was not again allowed to be lighted 
 till the sinking had proceeded down to a depth of several feet 
 below the bed of coal through which the gas first made its 
 appearance. The part of the pit at which the gas escaped 
 was then securely walled off, and a tube about 2 inches 
 square extended up the shaft to a height of 12 feet above the 
 surface of the ground. Through this tube the gas was allowed 
 to escape into the open air, which it continued to do in un- 
 diminished quantity for several years. Many observations 
 and experiments were made on the gas which was thus dis- 
 charged from the extremity of the tube. It was collected in 
 bladders, tied up and preserved for many days. When a 
 small pipe was fixed in the mouth of the bladder, and the gas 
 gently pressed out against the flame of a candle by squeezing 
 it, the gas was observed to take fire, and to burn so long as 
 the bladder was gently squeezed and the gas expelled. This 
 experiment on gas which had been so confined nearly a month 
 was made in the presence of the Royal Society. It was stated 
 that the gas when it first issued from the top of the tube was 
 as cold as frosty air, and that it would not take fire from a 
 spark, but required a flame to ignite it. 
 
 Some thirty years after the attention of the scientific world 
 was thus called to the nature and properties of inflammable 
 air or gas, — namely, about the year 1765, — we find a pro- 
 position made to the magistrates of Whitehaven by the then 
 agent of Lord Lonsdale, to convey this same gas through pipes 
 to light the streets of the town. The magistrates, it appears, 
 refused to entertain the subject, although the proposer, Mr. 
 Spedding, proved its perfect praticability by conveying the 
 gas into his own office and using it for the purpose of lighting. 
 
 In the “ Transactions of the Royal Society ” for the year 
 
8 
 
 APPLICATION OF COAL GAS 
 
 1789 is a paper by Dr. Clayton on the subject of distilling 
 pit coal. This paper is an extract from a letter written by 
 the author to the Honourable Bobert Boyle, who died in 1691. 
 The letter, therefore, was probably written some time before 
 this, and although not published till 1739, it appears clearly to 
 confer on Dr. Clayton the merit of an earlier experiment on 
 the mode of procuring gas from the distillation of coal than 
 that described by Dr. Hales in 1726. 
 
 I shall not quote in detail the experiments concerning the 
 spirit of coal contained in Dr. Clayton’s letter to Boyle, as 
 this letter appears in nearly every work on gas which has 
 since been published in this country, and must therefore be 
 familiar to most English readers. Those w T ho may wish to 
 see the complete extract from Dr. Clayton’s letter will, how- 
 ever, find it in page 59 of the “ Philosophical Transactions” 
 for the year 1789. The author first gives an account of the ditch 
 near Wigan in Lancashire, described by Mr. Shirley, in which 
 the water was said to burn. He proved; however, the fallacy 
 of this supposition, by causing a dam to be made and having 
 the water below the dam scooped out of the ditch. At first 
 the vapour would not take fire, but on digging down about 
 18 inches the vapour which arose from a shaly kind of coal 
 took fire from a candle, and continued burning. Suspecting 
 from the proximity of coal the true origin of this inflammable 
 vapour, the Doctor proceeds to say, that he procured some 
 coal and distilled it in a retort over an open fire. He de- 
 scribes the products of his distillation as a phlegm which first 
 came over (naphtha), afterwards a black oil (tar), and then 
 likewise a “ spirit arose which I could noways condense, 
 but it forced my lute or broke my glasses.” He discovered 
 accidentally that this spirit (the gas) was inflammable. He 
 then proceeded to collect it in bladders, and preserved it in 
 these for the amusement of his friends, before whom he was in 
 the habit of pricking holes in the bladder with a pin, and 
 gently compressing it till the small stream of gas took fire at 
 the flame of a candle, when it would continue burning till all 
 the gas was pressed out. It is curious that the process of 
 exosmose (hereafter explained) was observed at this early 
 stage of experiments on coal gas, for the Doctor says when 
 
TO USEFUL PURPOSES. 
 
 9 
 
 he filled calves’ bladders with the gas, it would lose its inflam- 
 mability in twenty -four hours ; he therefore recommends 
 good thick bladders like those of an ox. 
 
 The publication of Dr. Clayton’s experiments, although 
 they clearly pointed to the practicability of procuring and 
 storing up an inflammable gas derived by distilling coal, 
 appears to have attracted no further notice at the time. No 
 progress whatever appears to have been made in discovery 
 for many years afterwards. 
 
 To the celebrated Dr. Watson, afterwards Bishop of 
 Llandaff, we are indebted for the first notice of the important 
 fact that coal gas retains its inflammability after passing 
 through water into which it was allowed to ascend through 
 curved tubes. This is noticed amongst other results of Dr. 
 Watson’s experiments ip the second volume of his “ Chemical 
 Essays,” published in 1767. To this property is due much 
 of the facility with which the manipulations of a gas-making 
 establishment are carried on, particularly those connected 
 with the hydraulic main, and the purification by means of 
 wet lime. 
 
 With the exception of Bishop Watson’s experiments, the 
 whole subject of procuring from coal a valuable product in 
 the shape of inflammable gas appears to have slumbered for 
 more than half a century, till about 1790 we find an indivi- 
 dual, who was afterwards connected with one of the first 
 engineering workshops in the world, turning his attention to 
 the subject in a truly practical form. This individual was 
 Mr. William Murdoch, then resident at Truro, in Cornwall, 
 and afterwards connected for many years with Messrs. 
 Boulton and Watt’s establishment at Soho. There can be no 
 doubt as to the exclusive merit of this gentleman, whose 
 claim is unquestionable to the first practical application of 
 artificially manufactured gas to the purposes of lighting. 
 From his own narrations, written with all the earnest sim- 
 plicity which commonly attends the development of great 
 ideas, it even appears doubtful whether he was acquainted 
 with the papers of Dr. Clayton already alluded to. It is also 
 satisfactory to find that the pre-eminent claim of Mr. Mur- 
 doch is most clearly and distinctly confirmed by the celebrated 
 B 3 
 
10 
 
 APPLICATION OF COAL GAS 
 
 I)r. Henry, that brilliant philosopher; whose researches into 
 the nature of aeriform fluids have gained for him the admi- 
 ration of all Europe. 
 
 It appears from Dr. Henry’s statement, that, in 1792, Mr. 
 Murdoch actually lighted his own house and office at Redruth 
 with gas. He distilled the coal in iron retorts, and conveyed 
 the gas through tinned iron and copper tubes to a distance 
 of 70 feet. He used portable gas, carrying it about with 
 him in a bladder, or in bags of leather or varnished silk, and 
 also in vessels of tinned iron fitted with a small metal tube 
 and stop-cock, through which the gas, issuing from a minute 
 orifice, was ignited, and made to serve as a lantern in travel- 
 ling backwards and forwards between the mines and his 
 ow^u house. He is said to have excited the unbounded 
 astonishment of the country people, and to have confirmed 
 them in the belief that he was a real wizard, by travelling in 
 a steam carriage lighted up at night with gas contained in 
 bladders. Mr. Murdoch also at this early period made many 
 experiments on various kinds of coal, as the Swansea, Haver- 
 fordwest, Newcastle, Shropshire, Staffordshire, and some kinds 
 of Scotch coal. He also tried numerous forms of burners, 
 varying in many ways the shape and disposition of the orifices 
 for the emission of the gas. Thus, in some burners, the gas 
 was allowed to issue from many very minute openings, form- 
 ing a rose like the head of a watering-can, while in others 
 it was thrown out in long thin sheets, and again from circular 
 openings, on the principle of the argand burner. His atten- 
 tion was also directed to the necessity for purifying the gas, 
 and he certainly adopted the expedient of passing it through 
 water, but does not appear to have made use of lime, the 
 first application of which, to the purpose of purifying, appears 
 due to Dr. Henry and Mr. Clegg. Mr. Murdoch pursued 
 his experiments on the gas from coal, peat, wood, and other 
 inflammable substances, at such intervals of leisure as his 
 numerous other avocations would permit, principally with 
 the intention of avoiding the disagreeable odour peculiar to 
 it. About 1796, Mr. Murdoch communicated to Mr. James 
 Watt, jun., son of the celebrated James Watt, the engineer, 
 his views of employing gas as a substitute for lamps and 
 
TO USEFUL PURPOSES. 
 
 11 
 
 candles, and suggested that a patent should be obtained for 
 that object. This proposal was not, however, entertained 
 by Mr. Watt, on account of the heavy expenses his father 
 had incurred a short time previously in defending some patents 
 in connection with the steam-engine.* 
 
 In 1798 Mr. Murdoch lighted part of the Soho foundry 
 with gas, and exhibited his experiments to a few friends, 
 who, in after years, when his claims to priority for the adap 
 tion of gas were disputed, gave their testimony, and proved 
 the entire justice of his pretensions. 
 
 In 1799 a French engineer, of the name of Lebon, ob- 
 tained a patent in France for procuring gas from wood, 
 peat, cfec., and applying it to the purpose of illumination. 
 This circumstance has caused French authors (who ignore 
 the claims of Mr. Murdoch) to invariably award the merit 
 of priority of application to their compatriot. 
 
 In 1801, the brother of Mr. James Watt being in Paris, 
 wrote, saying, “ that if anything were to be done with Mr. 
 Murdoch’s gas, it must be done at once, as there was a 
 Frenchman in Paris who had similar ideas, and proposed to 
 illuminate that city by these means.” However, from some 
 unaccountable cause, the patent was never applied for ; and 
 it may be assumed that neither Mr. Watt nor Mr. Murdoch 
 had the slightest conception of the gigantic industry they 
 were on the threshold of establishing. 
 
 The year 1802 is very remarkable in conjunction with 
 gas lighting, for in that year, on the occasion of the procla- 
 mation of peace, a public exhibition of gas-lighting was made 
 at the Soho foundry ; and Mr. Matthews, an eye-witness, 
 states, “ the illumination of the Soho works on this occasion 
 was of the most extraordinary splendour ; the whole of the 
 front of that extensive building was ornamented with a great 
 variety of devices that admirably displayed many of the 
 varied forms of which gas-light is susceptible. This lumi- 
 nous spectacle was as novel as astonishing, and Birmingham 
 poured forth its numerous population to gaze at and admire 
 the wonderful display of the combined effects of science and 
 
 * Evidence of Mr. James Watt before Committee of House of Commons, 
 1809. 
 
12 
 
 APPLICATION OF COAL GAS 
 
 art.”* Mr. Murdoch, however, had many difficulties to over- 
 come before he attained the perfection which he exhibited 
 on this occasion, but he united sound scientific knowledge, 
 with great practical skill, and his perseverance enabled him 
 to triumph. 
 
 In this year M. Lcbon, before mentioned, had his house 
 in Paris illuminated by gas, and numbers of people of all 
 classes witnessed it with wonder and amazement. Also at 
 the same period, Mr. Winsor, who afterwards did so much 
 for the advancement of gas-lighting, being at Brunswick, 
 saw an account of the “ rapport ” or communication of 
 M. Lebon on gas for illuminating purposes, which had been 
 read before the French Institute ; and, to use his own words, 
 employed five years after, “ the thought struck him like 
 an electric shock.” He translated the communication of 
 M. Lebon into German and English, which he published as a 
 pamphlet. He also carried out a series of experiments in 
 connection with gas-lighting by distilling wood, &c., before 
 the duke regent, Charles William Ferdinand, and his court.*)' 
 And the same year he came to England (undoubtedly en- 
 tirely ignorant of what had been achieved by Mr. Murdoch), 
 with the intention of carrying the new enterprise into 
 operation. 
 
 In 1803 Mr. Winsor first publicly exhibited, at the Lyceum 
 Theatre, in London, the system of illumination by gas. Here 
 he delivered lectures on the subject, which he illustrated by 
 a variety of interesting experiments ; amongst them he 
 showed the means of conveying gas from one part of a build- 
 ing to another, and by the employment of different burners 
 was enabled to display the various forms which might be 
 given to its flame. He also proved, in a very elaborate 
 manner, the various advantages of gas-lighting, and its supe- 
 riority over all other artificial light, all of which time and 
 experience have fully confirmed. 
 
 In 1802 and 1803, Mr. Murdoch erected works for the 
 supply of gas to the premises of Messrs. Boulton and Watt; 
 and in 1804, Mr. George Lee, of the firm of Messrs. Phillips 
 
 * Matthews’ “ Historical Sketch of Gas Lighting.” 
 
 t French translation of Accum on Gas, by F. A. Winsor. 
 
TO USEFUL PURPOSES. 
 
 13 
 
 and Lee, of Manchester, had liia dwelling lighted by gas, in 
 order to test its salubrity, previously to its adoption in the 
 cotton mills of the above-mentioned firm, and the following 
 year the mills alluded to were so lighted ; and Mr. Lee's 
 evidence afterwards contributed considerably towards over- 
 coming the prejudice which existed against gas-lighting, and 
 to demonstrate its advantages and economy. The quan- 
 tity of light supplied to these mills was equal to that yielded 
 by 2,000 mould candles of six to the pound, or about 2,500 
 cubic feet per day on the average of the whole year. To 
 produce this quantity he used 7 cwt. of Wigan cannel coal, 
 yielding at the rate of 7,143 cubic feet of gas per ton of coal, 
 considerably less than the quantity made at the present day 
 from the same coal. 
 
 In his paper of 1805, vwhich was published in the “ Philo- 
 sophical Transactions ” for 1808, Mr. Murdoch does not 
 particularly describe the process which he followed in 
 making the gas, but merely states that the coal is distilled in 
 large iron retorts, and that the gas, as it issues from them, 
 is conveyed by iron pipes into large reservoirs, or gasometers, 
 where it is washed and purified previous to its being con- 
 veyed through other pipes or mains to the mills. He describes 
 the burners with some minuteness : these were of two kinds, 
 one on the principle of the argand lamp, and resembling it 
 in appearance ; the other a cockspur burner, consisting of a 
 small curved tube with a conical end, having three circular 
 apertures or perforations about one-thirtieth of an inch in 
 diameter, one at the point of the cone, and two lateral ones 
 The gas issuing through these apertures forms three diver- 
 gent jets of flame, somewhat like a fleur-de-lis. The whole 
 of the burners erected in the cotton-mills amounted to 271 
 argands, each of which gave a light equal to four mould 
 candles of six to the pound, and 633 cockspurs, each of which 
 gave a light equal to two and a quarter of the same candles. 
 The quantity of tallow consumed by each candle was at 
 the rate of four-tenths of an ounce, or 175 grains of tallow 
 per hour. 
 
 In his details of the comparative cost of lighting this 
 establishment with gas, as compared with candles, Mr. Mur- 
 
14 
 
 APPLICATION OF COAL GAS 
 
 dock’s comparison is very much in favour of the former. 
 Taking an average of two hours per day throughout the year, 
 the expense of candles would be £2,000 per annum, while 
 the cost of gas, including every expense of wear and tear and 
 interest on capital, did not exceed £600 a year. On an 
 average of three hours per day, the comparison is still more 
 in favour of gas, the expense of candles in this case being 
 £3,000 a year, while that of gas, estimated as before, would 
 only amount to £650. 
 
 Daring his experiments, and in erecting his earlier appa- 
 ratus, Mr. Murdoch tried various forms of retorts, which will 
 be more particularly noticed in the chapter on this subject, 
 so that it may be sufficient to observe that the earliest forms 
 were upright, with various contrivances for extracting the 
 coke which remained after the expulsion of the gas. Many 
 inconveniences attended this form, as well as an interme- 
 diate form, in which the retorts were placed in a diagonal or 
 inclined position. In time all the other contrivances gave 
 place to the horizontal retort, which is the mode of setting 
 universally adopted at the present day. 
 
 The success of Mr. Murdoch’s new mode of lighting the 
 cotton -mills of Lancashire appears to have enlisted a host of 
 ingenious and speculative persons, who entered eagerly upon 
 the course now open before them. About the years 1804 and 
 1805 w T e find the subject taken up by eminent chemists, such 
 as Dr. Henry of Manchester, who ably illustrated the mode 
 }f making gas in his lectures, and showed how readily and 
 economically it might be used as a substitute for oil and 
 candles. At this time also we find Mr. Clegg, an able 
 mechanician, also engaged in the same establishment as Mr. 
 Murdoch, where he entered as a pupil of Messrs. Boulton and 
 Watt, devoting all his energies to the mechanical appliances 
 connected with the successful application of gas. 
 
 Mr. Northern of Leeds, Mr. Pemberton of Birmingham, 
 and Mr. Accum were actively engaged at this time in experi- 
 ments on coal gas, the means of procuring it and applying it 
 to lighting purposes. Many of the contrivances and sugges- 
 tions of these gentlemen were highly ingenious, and they each 
 exhibited before the public gas-lights produced from appa- 
 
TO USEFUL PURPOSES. 
 
 15 
 
 ratas of tlioir own erection. The apparatus was of course on 
 a very limited scale, and it does not appear that any inter- 
 mediate process was practised between the retort and the 
 burner, except that of washing the gas by passing it through 
 water so as to condense and cool it before entering the gas- 
 holder. 
 
 Mr. Clegg appears to have struck off in the same direction 
 as Mr. Murdoch, and to have embarked about the same time 
 in the erection of private gas-works for cotton-mills and other 
 establishments. Thus he was engaged in lighting the cotton- 
 mill of Mr. Henry Lodge at Sowerby Bridge, near Halifax, 
 at the same time that Mr. Murdoch was erecting his works 
 at Messrs. Phillips and Lee’s mill. Indeed, Mr. Clegg, jun., 
 states, on the authority of his father’s journal, that the mill 
 at Sowerby Bridge was lighted a fortnight earlier than the 
 one under Mr. Murdoch’s direction. 
 
 In the following years, 1807 and 1808, Mr. Clegg pro- 
 ceeded to erect gas-works at various other mills, and at the 
 Catholic College at Stonyhurst, in Lancashire, where he first 
 introduced the system of purifying the gas from carbonic acid 
 and sulphuretted hydrogen by passing it through lime in a 
 separate vessel. Previous to this use of a separate purifier, 
 Mr. Clegg had used lime in the tank of the gas-holder, and 
 applied an agitator to keep it in motion, but the difficulty of 
 removing the saturated lime eventually led to its abandon- 
 ment, and the adoption of a separate vessel. 
 
 In this year Mr. Murdoch communicated to theBoyal Society 
 a very interesting account of the successful application of coal- 
 gas to lighting the extensive cotton-mills of Messrs. Phillips 
 and Lee, of Manchester ; for this communication, Count 
 Bumford’s gold medal was presented to him. The following 
 year Mr. Clegg communicated to the Society of Arts his 
 plan of an apparatus for lighting manufactories with gas, for 
 which he received a silver medal. About the same period he 
 erected a gas-apparatus for the manufactory of Mr. Harris, 
 at Coventry. 
 
 In 1801 Mr. Winsor obtained a patent for “ an im- 
 proved oven, stove, or apparatus, for the purpose of extract- 
 ing inflammable air, oil, pitch, tar, and acids, from, and re- 
 
16 
 
 APPLICATION OF COAL GAS 
 
 during into coke and charcoal, all kinds of fuel, which is also 
 applicable to various other useful purposes.” 
 
 “ A metal, brick, or earthen stove, oven, retort, or vessel, 
 is so constructed to reduce by means of fire and heat all 
 raw fuel of any kind into coke and charcoal, without any, or 
 little, consumption of the fuel, by which operation the smoke 
 being extracted from all raw fuel, is thus conducted through 
 cold air or water into a condenser, where, after being suffi- 
 ciently cooled and purified, it undergoes a natural chemical 
 resolution into tar, pitch, oil acid, ammonia, and inflammable 
 gas or air. 
 
 “ The inflammable gas or air may be led in a cold state 
 through tubes of silk, paper, earth, wood, or metal, to any 
 distance, in houses, rooms, gardens, places, parks, and streets 
 (and other places), to produce light and heat, or for any 
 other purpose, such as for increasing and multiplying force 
 and power.” 
 
 This was the first patent obtained in connection with gas- 
 lighting. 
 
 Having this patent, Mr. Winsor described himself as the 
 discoverer, inventor, and patentee of gas-lighting, and agi- 
 tated the necessity of forming a company for its full develop- 
 ment, so that the streets, shops, and private dwellings should 
 enjoy its advantages; but gas-lighting, like every other great 
 innovation, was looked upon by the public with excessive 
 distrust. In the event of its success, several branches of in- 
 dustry and commerce were doomed to suffer ; many interests 
 were, or supposed to be, at stake ; some of the chemical pro- 
 perties of gas were unknown ; great doubt existed as to its 
 safety, and fears as to its salubrity ; indeed, the danger of 
 explosion was magnified to the extent that it was asserted, 
 and believed, that a town could be destroyed by the explo- 
 sion of the main pipes in the streets ; and interested parties, 
 in order to prevent the establishment of gas-lighting, did not 
 scruple to appeal to the naval glory of the nation, and this 
 shortly after Nelson had achieved his great victories. “ If,” 
 said the opponents of the new light — “ if this become suc- 
 cessful, then our naval supremacy is gone, for at present we 
 obtain principally our artificial light from the whale fisheries : 
 
TO USEFUL PURPOSES. 
 
 17 
 
 these are the nurseries of our best sailors ; so if we destroy 
 the one, the other must be affected; if the fisheries no longer 
 exist, our navy must degenerate.’’ 
 
 These objections and arguments were put forth frequently 
 by the journals ; and Mr. Winsor, who by this time had 
 become intimately associated with gas-lighting, and in a 
 manner constituted himself its champion, met them with that 
 extraordinary courage, perseverance, and zeal which so 
 strongly characterised him ; but it is to be regretted that 
 although a gentleman of superior intelligence — with the 
 great qualities already awarded him — he lacked the scientific 
 knowledge so' essential for the fulfilment of his undertaking, 
 and unfortunately he was not aware of this deficiency. He 
 boldly combatted all possible objections with unexampled 
 ardour, but often committed the most egregious errors, 
 at one time asserting that our atmosphere in its pure state 
 was too powerful a medicine, and that a mixture of coal-gas 
 rendered it more salubrious; again, that gas w T ould not explode 
 when intermixed with air, and that its adoption would purify 
 the atmosphere ; whilst the prospectus issued by him con- 
 tained most extraordinary, exaggerated, and fabulous accounts 
 of the enormous profits to be derived from gas-lighting. All 
 this combined to retard his progress, and had he been of a less 
 sanguine nature, his task would have been comparatively easy. 
 These errors often brought down upon him the greatest ridi- 
 cule, in which some of the leading scientific journals took 
 prominent part ; but, undaunted, he still persevered. 
 
 At length, after having struggled, during four years, 
 single-handed, and, as it were, against the opinion of the 
 world — having by his letters, pamphlets, lectures, &c., proved 
 the advantages of gas — Mr. Winsor succeeded, in 1807, in 
 obtaining a capital of £20,000 by means of subscribers, 
 preliminary to the formation of a company ; which sum was 
 intended to demonstrate the practicability of manufacturing 
 and supplying gas on a large scale ; also for the purpose of 
 forming the company, and obtaining a royal charter. 
 
 Mr. Winsor then occupied extensive premises in Pall 
 Mall, on the site of the present Carlton Club. On the 
 basement he had gas manufacturing and other apparatus to 
 
18 
 
 APPLICATION OF COAL GAS 
 
 illustrate his lectures, demonstrating the practical utility of 
 gas for lighting, heating, and cooking, also its safety and 
 salubrity ; the public, on certain days, having free access to 
 take cognisance of the process. From these premises a pipe 
 was laid in Pall Mall to the corner of St. James’s Street 
 westward, and to the Haymarket eastward, with lamp-ptfsts 
 at short intervals, including several in front of Carlton 
 House, the residence of the Prince Pegent ; and thus Pall 
 Mall was the first street ever lighted by gas, and continued 
 so during the sessions of parliament of 1809 and 1810, whilst 
 endeavouring to obtain an Act of incorporation and charter. 
 
 The intention of Mr. Winsor, and his subscribers or 
 shareholders, in 1808, was to establish a company, and 
 obtain a royal charter or exclusive privilege for lighting all 
 the British possessions by gas ; and for this purpose they 
 proposed a capital of one million sterling.* A memorial was 
 accordingly presented to the king, setting forth the advantages 
 which would result from gas -lighting, and the production 
 and general employment of coke, praying for the concession ; 
 but after the question had been duly considered in Privy 
 Council, it was decided that his Majesty could not grant the 
 charter of incorporation until a Bill had been obtained from 
 parliament authorising the company. 
 
 The following year Mr. Winsor and his shareholders 
 again applied, with more moderate pretensions, to be esta- 
 blished as the “National Light and Heat Company,” but 
 were strongly opposed by Mr. Murdoch ; and on this 
 occasion many scientific witnesses were examined before a 
 committee of the House of Commons, who proved incon- 
 testably that gentleman’s claim to priority of adopting gas 
 for illumination. The evidence given is of the greatest 
 interest ; but the errors of a leading witness for the com- 
 pany, and the merits of Mr. Murdoch, caused the application 
 to be refused. 
 
 Amongst Mr. Winsor’s subscribers were some eminent 
 men of the day, and, like himself, of the greatest perseve- 
 rance and zeal. They had already been too familiar with 
 difficulties to be discouraged by defeat ; and again, in 1810, 
 * French translation of Accum on Gas, by F. A. Winsor. 
 
TO USEFUL PURPOSES. 
 
 19 
 
 they applied to parliament, and succeeded in obtaining an 
 Act of incorporation as the “ Gas-light and Coke Company,” 
 with a capital of £200,000. But the enterprise was looked 
 upon as so visionary, that it was asserted this Act was granted 
 in order to make a great experiment of a plan of such extra- 
 ordinary novelty. 
 
 The royal charter was granted to the company in 1812 ; 
 but the privileges accorded by that charter were neither 
 liberal nor encouraging ; for by it the company had no 
 exclusive right, so as to prevent any other persons or com- 
 pany from entering into competition with them. The power 
 and ‘ authority granted were very moderate ; and whilst the 
 company were under severe restrictions, they were confined 
 to the metropolis, and were liable to have the charter annulled 
 if they failed to fulfil their obligation. 
 
 The very prominent part taken by Mr. Winsor in esta- 
 blishing gas lighting has often been passed over, whilst his 
 errors, the result of a very sanguine mind, have been 
 displayed with all vigour ; and whilst the sacrifices he made 
 have been forgotten, he has been represented as being 
 actuated entirely by selfish motives ; but the evidence given 
 before parliament on the subject of gas-lighting in 1809 and 
 1810 proves beyond doubt the important services he rendered 
 to that art, and that through his instrumentality was the first 
 gas company established. The injustice of the charge of 
 selfish interestedness may be met by the fact that in 1815 
 and 1816, instead of remaining in England, and profiting by 
 the position his labour and energy had created him, he went 
 to France, there to fight again the battles he had so often 
 fought in favour of gas-ligjiting ; and Mr. Peckstone only 
 does justice w r hen, speaking of Mr. Winsor, he says, “ San- 
 guine in his expectations, indefatigable in his exertions, and 
 zealous in his cause, he directed all the talents and energy he 
 possessed to the one great object, and thus achieved much 
 for the public good ; but with all his ardour, his skill, and 
 his exertions, he, like many others, achieved but little towards 
 promoting his own comfort, or the comfort of his family.” 
 
 The Gas-light Company being thus legally established, 
 they commenced their operations at a wharf and premises 
 
20 
 
 APPLICATION* OF COAL GAS 
 
 in Canon Row, Westminster ; and there the new industry 
 was left in the hands of chemists, who, however competent 
 they might have been in their legitimate profession, were 
 void of that mechanical knowledge and skill so essential to 
 their task : in consequence, numerous experiments were 
 made, at- the expense of a large portion of the capital 
 invested ; and the shareholders, who had hitherto shown 
 such extraordinary patience so long as the enterprise was 
 only in project, now began to lose heart, when they saw so 
 much money sacrificed, and so little done towards com- 
 mercially realising their hopes and expectations. 
 
 At this period, when the practical application of gas ap- 
 peared doubtful, the company had the good fortune to engage 
 Mr. Clegg, before-mentioned, as their engineer. This gentle- 
 man had already acquired considerable experience in erecting 
 gas-works. His genius rendered him capable of surmounting 
 the greatest difficulties he encountered ; and he may with 
 justice be said to have established the manufacture of gas. 
 
 The main features in the present system of gas-lighting 
 which are due to Mr. Clegg are, the system of wet-lime puri- 
 fication ; the hydraulic main, with its contrivance of dip-pipes 
 for isolating the retorts ; the mode of attaching the mouth- 
 pieces to the retorts ; the governor or regulator for adjusting 
 the delivery of gas into the mains; to which must be added 
 the gas-meter in its earliest and most novel form, which was 
 afterwards perfected by Mr. John Malam, aided by Mr. 
 Samuel Crosley, and which will claim particular attention at 
 a future page. 
 
 These are the principal parts of the mechanism of gas 
 apparatus introduced by Mr. Clegg, and which have become 
 essential parts of the gas manufacture, while there are many 
 other contrivances of perhaps equal ingenuity and merit 
 which have not been successful. Among these are the rota- 
 ting or web retort, of which a notice will be found further 
 on ; the inferential dry gas-meter, the collapsing gas-holder, 
 and an apparatus for the decomposition of oil, tar, &c. A 
 review of these various inventions undoubtedly places the 
 name of Mr. Clegg in the very foremost rank of those who 
 have advanced the practice and science of gas-lighting. 
 
TO USEFUL PURPOSES. 
 
 21 
 
 In December, 181 3, Westminster Bridge was first lighted 
 by gas ; and in the following year the old oil lamps were 
 removed from the streets of St. Margaret’s parish, West- 
 minster, and gas-lights put in their place ; this being the 
 first parish w'hich applied for a contract to have the streets 
 lighted with gas. / 
 
 In the year 1814, when the allied sovereigns visited this 
 country, and a general illumination took place in commemo- 
 ration of the peace of Europe, the new light was brought 
 into requisition, and exhibited to thousands of admiring 
 spectators, in illuminating a magnificent pagoda erected in 
 St. James’s Park. This building was instantaneously lighted 
 up by a simple contrivance ; and in a single instant of time 
 10,000 lights burst forth, and formed an immense and 
 brilliant fountain of fire. In the following year Guildhall 
 was lighted up with gasj and on this occasion the public 
 papers teemed with extravagant praises of the new light. Its 
 mild splendour was described as “ shedding a brightness clear 
 as summer’s noon, but undazzling and soft as moonlight, 
 altogether forming a magnificent combination worthy the 
 inauguration of the presiding citizen of the great city.” 
 
 After the founders of the gas company had striven against 
 and overcome the errors of public opinion — had become 
 established — had expended considerable sums in experiments, 
 and incurred great losses in carrying the new science to a 
 successful issue — this done, and the trade being open to all, 
 then arose rival companies in the metropolis, these being the 
 City of London, the South London or Phoenix, and the 
 Imperial. Other companies were also established, in Glasgow’, 
 Edinburgh, Manchester, Bristol, Bath, Leeds, Chester, Chel- 
 tenham, Macclesfield, Exeter, Birmingham, Rochester ; and 
 such was the rapid progress of gas-lighting from 1814, that 
 all the works in these, as in many other towns, were in 
 operation in the year 1819. 
 
 From about the year 1815 the names connected with gas- 
 works become so numerous, inventions of all sorts and descrip- 
 tions multiply so fast, and the records of the Patent Office 
 exhibit such a spirit of invention, that it would be impossible 
 to follow them in anything like detail. I must therefoie bo 
 
22 
 
 APPLICATION OF COAL GAS 
 
 satisfied with briefly noticing a few of the successive steps by 
 which the practice and science of gas-lighting advanced until 
 it entirely superseded all other modes of public lighting in the 
 metropolis and other large towns, and even came to be exten- 
 sively used for domestic illumination in place of candles and 
 lamps. 
 
 In 1815 Mr. John Taylor patented the means of obtaining 
 gas from oils, fat, resin, and other oleaginous substances. The 
 superiority of the gas thus obtained is unquestionable. It 
 contains a much larger quantity of olefiant gas than that 
 from common coal, and it had long been known that olefiant 
 gas, containing as it does double as much carbon as ordinary 
 carburetted hydrogen, was by far the most valuable ingre- 
 dient for illumination in any inflammable gas. The gas from 
 oil would also be free from sulphuretted hydrogen, and other 
 impurities which cause considerable expense in the purifica- 
 tion of coal gas. In addition to this, the advocates of oil gas 
 contended that the expenses of production and management 
 would be much less than in a coal-gas establishment, and that 
 the large supply of oil required would afford employment to 
 thousands of fishermen, who would be engaged in the capture 
 of fish suitable for yielding oil in sufficient quantity. Of 
 course all considerations of this nature require to be tested by 
 actual practical experience, and when this was applied to the 
 case of lighting by means of oil gas, the results were widely 
 different from those w 7 hich had been anticipated in theory. It 
 was found impossible to work the establishments with any- 
 thing like the same economy as those for producing coal gas, 
 and all the companies, without exception, found it w T as hope- 
 less to expect any dividend for their outlay. Under these 
 circumstances the oil-gas works w^ere abandoned one by one, 
 and apparatus for distilling coal substituted in their place. 
 
 But for some years oil gas w T as considered to be a for- 
 midable rival to coal gas ; its vast superiority w 7 as supported 
 by some of the first chemists of the day ; amongst them 
 were Mr. Brande, Professor of Chemistry at the Royal Insti- 
 tute, Mr. Michael Farraday (who has since acquired a world- 
 wide reputation), then assistant to Mr., afterwards Sir, 
 Humphry Davy, and Sir William Congreve, the govern- 
 
TO USEFUL PURPOSES. 
 
 23 
 
 ment inspector of gas works for the metropolis. According to 
 these gentlemen, the light obtained from oil gas, compared 
 with that from coal gas, was in the prop^j±feli^Qf three and 
 a half to one. They also asserted that^as from oipfcas supe- 
 rior on many accounts to that from dml. Sir W^^t^Con- 
 greve stated, “ the most important/feature^aT the oil 
 
 gas was its safety; as from the v^lry^ narrow Jiipits^^\^e 
 explosive mixture that can be forme® qf this gfc&^it is.sctp^ely 
 possible that an accident can occur. V'" ^ S 
 
 Mr. George Lowe, who for mai^X^ears, so l^nouyabljf 
 filled the post of consulting engineei\tf(0the Cliar£ered*l3a£ 
 Company, being at that time at Derhw'^as thenrst al 
 most conspicuous person who entered the^ld to oppose/jpe 
 advocates of oil gas ; and his extensive lurrie d g the 
 subject fully qualified him for engaging in the contest His 
 communications to the various scientific journals on the sub- 
 ject, while carrying conviction with them, were always cha- 
 racterised by the peculiar wit and good-humour that those 
 who have had the pleasure of his acquaintance can readily 
 understand. 
 
 The evidence given by Mr. Lowe before a committee of 
 the House of Commons in 1823 on oil gas, was the severest 
 blow it had received ; for he then convinced the committee 
 of inquiry, by actual experiment, that oil gas was as explosive 
 as that produced from coal ; that the light of oil gas was 
 barely double that of the other ; and that very similar impu- 
 rities existed both in oil and coal gas. His testimony on 
 those occasions was so clear and positive, as to carry convic- 
 tion with it, and sufficient to shake the opinions of those who 
 hitherto had held oil gas in the highest estimation. 
 
 In 1819 we find Mr. David Gordon obtaining a patent for 
 compressing gas into suitable vessels fitted with proper valves, 
 and capable of being carried about, so as to render the gas 
 portable. This contrivance, which can scarcely be called an 
 invention, as it had been practised by Mr. Murdoch many 
 years before, led to the formation of the “ London Portable 
 Gas Company.’* However, after carrying on business some 
 
 * This was somewhat erroneous, as the force of explosion frrm a given 
 quantity of gas is in proportion to the carbon combined therewith. 
 
24 
 
 APPLICATION OF COAL GAS 
 
 time, it was found tliat tlie scheme would not answer, and 
 the company was ultimately broken up. About the same 
 time Professor Daniel], F.R.S., was engaged in an unsuc- 
 cessful attempt to make gas from resin. It is said that his 
 apparatus was highly ingenious, but the project on trial was 
 soon abandoned, from inability to compete with coal-gas works. 
 The Act for lighting Bristol with oil gas was obtained as late 
 as 1823, in spite of the warnings of several eminent gas 
 engineers that the project would prove unsuccessful. The 
 truth of these warnings was amply confirmed in the course 
 of a few years. 
 
 Paris was first lighted by gas in 1820, and although pre- 
 viously strong prejudices existed against the project, yet, 
 when carried out, it produced a corresponding enthusiasm ; 
 and, to give an instance, a French author of the period, 
 writing to a friend, describing the new light, said, “ where 
 gas-light exists there is no night ; where gas-light is, there 
 is continuous day.” He also mentioned, in the most glowing 
 terms, the transcendent beauty of the ladies, as seen thereby. 
 
 Here, it must be observed, that all the bright prospects, 
 all the enormous profits calculated to be derived from gas 
 enterprises, were far from being realised ; for, at the com- 
 mencement, and for years after, commercially, they failed 
 — few, if any, were successful. The causes of this loss were 
 various ; in some instances the main pipes were either so 
 bad, or laid in such a defective manner, that a large portion 
 of the gas escaped. The extravagance of many consumers 
 in burning, which no personal surveillance could control or 
 counteract, was another serious source of evil. If we add 
 the want of experience in the manufacture and distribution 
 of gas, and the amount of misplaced and abused confidence, 
 then we can understand how gas companies were unprofit- 
 able. And to such an extent was this kind of property 
 depreciated, that a London company was disposed to sell its 
 plant, &c., to a rival establishment for about one-twentieth 
 part of its cost ; a difference of a comparatively insignificant 
 sum prevented the sale being effected. 
 
 Such is a brief sketch of the leading historical facts which 
 mark the progress of gas-lighting till within the last thirty 
 
TO USEFUL PURPOSES. 
 
 25 
 
 years. The chapters which follow will explain the modern 
 system of constructing and working establishments for manu- 
 facturing gas from coal. I can only hope, however, to 
 present a fair selection of the various practices and contri- 
 vances, which vary very much at different works. A gra- 
 dual spirit of improvement has characterised the progress of 
 all gas establishments, and improvements made almost imper- 
 ceptibly, year after year, have brought their efficiency up to a 
 high standard. This is evidenced in a most practical manner 
 both by the increased produce of gas, and by the diminution 
 of price to the consumer. In the metropolis few of the 
 companies now charge more than 4$. per 1,000 feet for gas, 
 yet the price a few years ago ranged from 8s. to 10s. While 
 molt of the general arrangements have remained the same, 
 more especially those for which we are indebted to Mr. 
 Clegg, a constant succession of improvements in the sub- 
 ordinate parts has vastly improved the value and efficiency 
 of gas-lighting, thus alike benefiting the companies and the 
 public. 
 
 Amongst the most important of these improvements are, 
 the very general adoption of clay retorts instead of iron, the 
 more perfect system of main laying, by which the loss of gas 
 is reduced almost to a minimum, the use of the scrubber, the 
 improvements in purification — in short, a systematic change 
 has taken place, ensuring alike economy in the manufacture 
 and distribution of gas. Again, as connected with the dis- 
 tribution of gas, the modern system of fittings deserves espe- 
 cial commendation when contrasted with the very imperfect 
 mode in which this kind of work was originally executed. 
 The business of the gasfitter — one of considerable skill and 
 nicety — has been, in fact, like many others, created since the 
 general introduction of gas-lighting. When we consider 
 the difficulty of confining in metallic pipes a subtle aeriform 
 fluid of only half the specific gravity of common air, convey- 
 ing it into all kinds of corners, and all parts of buildings, in 
 addition to the use of innumerable cocks and burners, the 
 delicacy and nicety required in every part of the gasfitter’s 
 manipulation are entitled to considerable admiration ; while 
 the advantage he has derived from the beautiful invention of 
 
 O 
 
26 
 
 ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 welded iron tubes and pewter-drawn tubes, contrasted with 
 every other form of metallic tubing originally in use, adds 
 considerably to his facilities. Gas may now be burnt in 
 private houses without the slightest effluvia or escape from 
 any of the pipes, joints, or fittings, and if properly purified, 
 may be burnt in any kind of room, however highly orna- 
 mented by gilding and otherwise, without being in any way 
 prejudicial 
 
 CHAPTER II. 
 
 ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 In all the contrivances which have been used for producing 
 light from oleaginous or fatty matters, either in lamps or in 
 the form of candles, the various component parts of gas, as 
 the carbon and hydrogen, are always vaporised and put into 
 the form of gas before their combustion takes place. In 
 this point of view every wick burning in any kind of lamp 
 or candle is, in fact, a small laboratory for the production of 
 gas, which is burnt or consumed at the instant of its pro- 
 duction. It was reserved for the chemistry of our own day 
 to point out this analogy, as it was reserved for the practical 
 skill of our engineers and machinists to bring to perfection 
 the means of producing this gas on a large scale, of storing 
 it for an indefinite period, and then sending it forth whenever 
 required, into our streets and houses, to communicate light, 
 and enable mankind to pursue their useful and laborious avo- 
 cations alike when darkness shrouds the earth, as well as in 
 the light of day. 
 
 A beautiful action takes place in the combustion of an 
 ordinary lamp or candle, in which the wick surrounded by 
 flame represents a series of capillary tubes to convey the 
 melted matter in the form of gas into flame. This action 
 
ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 27 
 
 will be very apparent to any one who will watch the process 
 of combustion in an ordinary wax or tallow candle. First, 
 he will perceive a cup of melted matter around the wick, in 
 which a great number of small globules are seen constantly 
 in progress towards the wick. Many of these globules are also 
 seen standing on the wick, studding it all over like little 
 sparkling diamonds. Let us consider what these globules 
 contain. They are filled with the inflammable gas produced 
 by the heat applied to the melted w^ax or tallow, but fortu- 
 nately for the success of this method of burning, these 
 globules do not break and set free the gas until they come 
 into close contact with the flame, when the heat becomes so 
 great that the expansion of the gas causes each little globule 
 to bleak and add its contents to the already burning flame. 
 How beautiful is this provision ! How exquisitely constituted 
 are the properties of matter to cause this beautiful result ! 
 In every common candle we behold an apparatus of wonder- 
 fully refined ingenuity, in which gas is being enclosed in 
 little microscopic pellicles, which are floated to the base of 
 the wick. There hundreds of these little tiny globules are 
 seen ascending the wick, while hundreds of others are every 
 instant exploding and discharging their contents into the 
 flame, which is thus made up by the instant combustion of 
 gaseous matter at the moment when it leaves the liquid form, 
 through the medium of this intermediate stage, in which 
 it assumes the form of an infinitely small translucent glo- 
 bule. 
 
 It is obvious if the gas were to be actually formed at the 
 surface of the small cup of melted fluid already spoken of, 
 the surface being usually half an inch below the nearest part 
 of the flame, that the gas would immediately diffuse itself 
 through the air, and combustion could not proceed. It is 
 only through the property which the gas possesses of taking 
 an intermediate form and not finally assuming its gaseous 
 condition till it reaches the flame, that the effect of continued 
 combustion is preserved. 
 
 The daily operations of the gas manufacturer, or manager, 
 are so intimately associated w 7 ith chemistry, as to render a 
 partial knowledge of that science (at least so far as regards 
 c 2 
 
28 
 
 ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 the gases he has to treat with) of the first necessity; it is 
 therefore intended to give a brief outline of the subject. 
 
 Chemistry is the science which teaches us the composition 
 of bodies, and the laws regulating the combination of the 
 elements of which they are composed. For the purposes of 
 study, it is usually divided into two branches, viz., organic 
 and inorganic chemistry. 
 
 The first branch relates to every living object, from the 
 largest being to the smallest animalcule ; likewise all vegetable 
 life, from the most stupendous tree, to the minutest trace of 
 vegetation. These, having organs of vitality, are with much 
 propriety called organic bodies. The other class, which con- 
 sists of inanimate objects, which neither live nor die, 
 having no such organs of vitality, are called inorganic 
 bodies. 
 
 All organic and inorganic bodies, constituting everything 
 accessible to man, consist of, or are composed of, about sixty- 
 four simple substances called elements , which are so named 
 because they cannot, by any known means, be decomposed ; 
 that is, resolved into simpler kinds of matter. These ele- 
 ments combine with each other in certain relative propor- 
 tions, and form substances called compounds. 
 
 Of the elements, about fifty belong to the class of metals, 
 as iron, gold, copper, lead, &c.; but those which immediately 
 interest the gas manufacturer are few in number, being only 
 five, viz. oxygen, hydrogen, nitrogen, carbon, and sulphur, 
 which are of the greatest importance, on account of their 
 vast abundance, because one or more of these exist in almost 
 every substance or compound in nature, and they all influence 
 the manufacture or distribution of coal gas. 
 
 To render the combination of the elements and the forma- 
 tion of the compounds intelligible, we may compare the 
 chemistry of our globe to a language having about sixty-four 
 letters, each of which letters represents an element; these 
 .etters, in unison, form the words, or compounds, and the 
 compounds comprise the earth and all that is on its surface. 
 
 A letter in a language resembles an element in chemistry, 
 inasmuch as neither can be reduced or decomposed into any- 
 thing less than itself. 
 
ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 20 
 
 Letters combine in various manners and ways to form 
 words ; so the elements combine in a similar manner to form 
 compounds. 
 
 The nature of the word is dependent on the letters com- 
 posing it, and on their disposition ; so in chemistry, the nature 
 of the compound depends on the composition, and disposition 
 of its elements. 
 
 And to continue the comparison, the five elements named 
 may be compared to the vowels, without which no word can 
 be formed ; so few compounds exist without the presence of 
 one or more of the elements named. 
 
 The elements which comprise a substance or compound 
 are discovered by employing means to separate them from 
 each other, which process is called decomposition, and is the 
 basis of what is termed analysis. This decomposition is very 
 frequently effected by N the application of heat — thus, the 
 black oxide of manganese (a natural compound, an union of 
 two elements, the one a metal called manganese, and the 
 other oxygen), when submitted to a red heat in a retort, is 
 decomposed, part of the oxygen being separated and expelled 
 as gas, and a lower oxide of manganese is left in the retort. 
 Here it is obvious that the oxygen now existing as gas must 
 have formed part of the solid previously to the compound 
 being exposed to the heat, and if the solid be weighed before 
 and after the process, the loss of weight by the separation 
 of part of the oxygen will be found to be considerable. 
 
 Again, with limestone, a compound of three elements, 
 carbon, oxygen, and calcium, or lime, some descriptions of 
 which have almost a flinty appearance, when exposed to a 
 great heat, as when destined for building purposes, loses 
 about from 35 to 40 per cent, of its weight, which is driven 
 off as a compound gas, consisting of carbon and oxygen, 
 forming carbonic acid. The residue, deprived of these, is 
 entirely altered in its nature, being no longer the hard 
 rock, but lime, which crumbles to dust on exposure to the 
 atmosphere. Hence, the elements of these gases must pre- 
 viously have existed as a solid, composing part of the lime- 
 stone. 
 
 The decomposition of coal, by heat, as in the manufacture 
 
30 
 
 ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 of coal gas, is entirely a chemical operation. Coal contains all 
 the five elements named, and the result of the decomposition 
 is, that the greatest portion of the hydrogen and the volatile 
 carbon are expelled as gas ; a portion of the oxygen and 
 hydrogen form water ; the nitrogen, with a portion of hydro- 
 gen, constitutes ammonia; a portion of the sulphur and 
 hydrogen comprise the impurity, sulphuretted hydrogen. 
 Another portion of sulphur unites with carbon, and produces 
 the troublesome impurity called bisulphide of carbon. The 
 tar is a compound of several of these elements ; and the coke 
 left in the retort is fixed carbon, intermixed with earthy 
 substances and a minute portion of sulphur. 
 
 Water is composed, by weight , of one of hydrogen and 
 eight of oxygen ; by means of voltaic electricity, it may be 
 decomposed into its two component gases, the one being 
 liberated at what is called the positive pole, and the other 
 at the negative pole of the battery. These gases, when 
 collected, are found to be in the exact proportion, by volume , 
 of two of hydrogen to one of oxygen. If we, therefore, 
 take into consideration their respective weight and volume, 
 oxygen is found to be sixteen times heavier than hydrogen. 
 
 Now, if the gases produced from the decomposition of 
 water are placed in a strong vessel, say a soda-water bottle, 
 so as to fill it, and in the same proportions that they were 
 liberated, on a lighted match being applied to the mouth of 
 the bottle an explosion with a loud report takes place ; the 
 two gases ignite, and at the same moment re-unite, forming 
 water, which bedews the side of the bottle. By the first 
 experiment water is resolved into the two gases of which it 
 is composed ; and by the second, these, again, are converted 
 into the liquid form — striking illustrations of the truth of 
 chemistry. This is but one of the many instances, where a 
 substance can be decomposed and afterwards again caused to 
 assume its former state. 
 
 From the foregoing illustrations it is manifest that oxygen 
 enters into the composition of solids, as when it comprises 
 part of the oxide of manganese, limestone, &c.; that it exists 
 in liquids such as water ; and that when separated from its 
 compounds it exists only as gas. Most elements can exist 
 
ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 31 
 
 in three different states of aggregation — the solid, the liquid, 
 and the gaseous. 
 
 The form of solids and liquids is well known, but that of 
 gases, for the general reader, requires some explanation. 
 
 Gases are permanently elastic fluids — vapour or steam 
 convey to us the idea of the bulk of gas. But this, by a 
 diminution of temperature, condenses and becomes liquid ; 
 whereas gases, under all ordinary circumstances, are perma- 
 nent in their state. Smoke issuing from a chimney or else- 
 where, is a mixture of several gases, combined with vapour 
 and small solid particles of carbon, called soot. 
 
 Gases are of various kinds, and very dissimilar in their 
 properties ; and, although frequently invisible, the chemist’s 
 art teaches him to distinguish the one from the other with 
 the greatest certainty, so as to render them as palpable to 
 the mind, if not to the ^ye, as the different solids which sur- 
 round him. Each description of gas has some distinguishing 
 characteristic, such as weight, odour, colour, power of ex- 
 tinguishing fire or of supporting its combustion, or the man- 
 ner it acts on particular substances, called tests, signifying 
 testimony. 
 
 These tests are substances which are known to change in 
 their appearance and nature, in a peculiar and characteristic 
 manner, when exposed to the action of certain gases or 
 liquids. 
 
 Thus, an impurity in coal gas is called sulphuretted hydro- 
 gen (which, in ordinary language, may be rendered sulphured 
 hydrogen), being a compound of sulphur and hydrogen ; and 
 when this is allowed to act upon a piece of paper, saturated 
 with the acetate, or sugar of lead, the paper immediately 
 becomes blackened, and ultimately assumes a metallic appear- 
 ance, occasioned by the sulphur of the sulphuretted hydrogen 
 entering into combination with the lead which was previously 
 in union with the acetic acid. 
 
 Thus, the acetate of lead is one of the substances acted 
 upon by the impurity in a perfectly understood manner, and 
 is, therefore, selected as a test for sulphuretted hydrogen. 
 There are, however, several kinds of tests ; amongst them is 
 the method of ascertaining the presence of certain gases by 
 
32 
 
 ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 means of certain absorbents which cause them to become 
 fixed, and to assume a liquid or solid state. A very general 
 test for discovering the presence of acids or alkalies, is litmus 
 paper, which in its natural state is blue, but when treated 
 with the least quantity of a weak vegetable acid, such as 
 vinegar, becomes red ; and this when acted upon by an alkali 
 resumes its former colour. The test generally used to detect 
 the presence of ammonia is turmeric paper, which is of a 
 peculiar yellow colour, but becomes brown when submitted 
 to the action of that compound. 
 
 With this introduction, we will consider the properties of 
 the five elements named, and afterwards their combination in 
 forming coal gas and its impurities. 
 
 Oxygen . — This is by far the most abundant element in 
 nature, and in its gaseous state forms more than one-fifth 
 part of the atmosphere by which our earth is surrounded. 
 As a liquid, in union with hydrogen, it constitutes by weight 
 eight-ninths of all water ; as a solid, it is a portion of 
 innumerable organic and inorganic bodies ; and is estimated 
 to form about one -third of the mineral crust of our globe. 
 
 Oxygen, when free, that is, when uncombined with any 
 other element, exists only as a gas (all attempts to reduce it 
 to a fluid having failed) ; and this occurs either when it is 
 emitted by the leaves of plants, &c., or when by the agency 
 of man it is separated from other elements with which nature 
 has caused it to combine, and form certain compounds or 
 substances. This element is the support of all animal life 
 and combustion, and possesses very peculiar properties ; for 
 instance, a body which burns in air, when it is immersed in 
 oxygen gas burns with vastly increased splendour ; and the 
 wick of a recently extinguished candle, having the least part 
 red-hot, when inserted into a jar of this gas is immediately 
 re-lighted; and a piece of charcoal with the smallest point 
 ignited, when so treated burns with great brilliancy. 
 
 Oxygen gas is inodorous, colourless, and rather heavier 
 than air ; and it may be termed the aerial food of animal • 
 life, for at each respiration a portion of it, intermixed with 
 nitrogen, is received into the lungs, acts on the blood, and is 
 afterwards ejected as a poisonous compound, carbonic acid gas. 
 
ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 33 
 
 Oxygen, or any other natural element, can only be obtained 
 from a compound which possesses it, and by adopting means 
 to separate the required element from the compound. Thus, 
 chlorate of potash, red oxide of mercury, and black oxide of 
 manganese, in common with many other substances, contain 
 a large quantity of oxygen, which is easily separated as a 
 gas by means of heat. 
 
 For example, red oxide of mercury is a mixture of oxy- 
 gen and quicksilver, in the form of a red powder ; and if a 
 few grains of this be placed in a test-tube and held over the 
 flame of a lamp or gas-burner, the heat expels the oxygen 
 as a colourless gas, leaving the quicksilver in its fluid state. 
 This is decomposition, and was the means first employed to 
 obtain oxygen by its discoverer. 
 
 But a more economical manner of obtaining this gas is by 
 taking a quantity of black oxide of manganese (of which 
 one pound will evolve about 1,400 cubic inches of oxygen), 
 placing it in a cast-iron retort, and distilling similarly to the 
 distillation of coal for the production of gas ; the oxygen gas 
 can be collected in a gas-holder, or other vessel, for use when 
 required.* One ounce of chlorate of potash, by careful 
 application of heat, will afford about two gallons of oxygen. 
 
 Hydrogen . — This element is also very abundant, and does 
 not exist free or uncombined in nature. It is a constituent 
 of all animal and vegetable substances, forming, by weight, 
 one-ninth part of water, and is a portion of most com- 
 bustible bodies. Hydrogen gas is colourless and tasteless, and 
 when quite pure is without odour ; it is inflammable when 
 issuing from an orifice and intermixing with the atmosphere : 
 burning with a faint violet colour, giving great heat, but 
 very little light. 
 
 This gas is the lightest substance in nature, being a little 
 more than one-fifteenth part of the weight of air. It is an 
 invariable component of coal gas, both in a free state and in 
 combination with carbon, constituting certain hydro-carbons, 
 such as light carburetted hydrogen (or marsh gas), olefiant 
 gas, &c. 
 
 * As these experiments are attended with danger, the reader should not 
 attempt them without having some instruction on the subject. 
 
 o 3 
 
34 
 
 ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 Hydrogen, for perfect combustion, requires eight times its 
 weight or half its volume of oxygen, as already demonstrated 
 by experiment, the result of the combustion being water ; 
 and in every case wherever artificial light is obtained by 
 burning oil, tallow, gas, &c., this production of water is con- 
 tinually taking place, arising from the hydrogen intermixed 
 with the material being consumed uniting with the oxygen 
 of the atmosphere. The water is distributed as vapour in 
 the atmosphere wherever produced, unless means be employed 
 to condense and collect it. Whenever gas-lights are burned 
 in a shop-window without proper ventilation, the vapours 
 are condensed by the cold glass, an inconvenience which is 
 familiar to all ; or a bottle of cold water brought into a room 
 where lights are burning is speedily covered with a dew, 
 caused by the condensation of the vapours by the cold water. 
 
 A simple way to obtain this gas is by passing a slow 
 current of steam through a small iron tube (f or 1-in. gun 
 barrel) loosely filled with iron borings ; the' tube is placed 
 across a suitable furnace, or blacksmith’s forge, and heated to 
 bright redness ; the steam on passing is decomposed into the 
 two elements of water, viz., oxygen and hydrogen — the 
 oxygen combining with the iron, forming the oxide of iron ; 
 while the hydrogen gas being set free, can be collected in a 
 holder. 
 
 Another convenient method is, by putting a few pieces of 
 zinc into a glass vessel, and pouring on them a mixture of 
 one part of sulphuric acid, and four or five parts of water ; 
 the gas then rises in bubbles. In this experiment the zinc 
 unites with the oxygen of the water, and subsequently with 
 the sulphuric acid, and the hydrogen is liberated. 
 
 Thus, hydrogen exists in solids forming part of animal 
 and vegetable substances ; in liquids, i.e. as a component of 
 water, and can be obtained in its gaseous state by decom- 
 posing one of its compounds, such as water, &c. 
 
 Nitrogen . — This element is so called from its being the 
 basis of nitric acid, and nitre, and is sometimes named azote, 
 from its incapability of supporting life. 
 
 Nitrogen constitutes nearly four-fifths of the air we 
 breathe, and serves to temper the effects of the oxygen, 
 
ON THE CHEMISTRY OF GAS-LIGHTING. 
 
 35 
 
 which, if alone, or even when in moderate excess of the 
 proportion stated, would be too energetic. It is also a com- 
 ponent of all animal tissues, muscles, &c. 
 
 Nitrogen gas is slightly lighter than air : it has neither 
 colour, taste, nor smell ; it supports neither combustion nor 
 respiration ; and is characterised by its negative properties, 
 rather than by possessing any inherent poisonous qualities, 
 such as are peculiar to carbonic oxide, or carbonic acid. Nitro- 
 gen is of interest to the gas manufacturer on account of its 
 influence on the combustion of gas ; also because it is one 
 of the components of the alkali ammonia which is always 
 generated, during the distillation of coal, in making coal gas. 
 
 In order to demonstrate the composition of atmospheric air, 
 let us take a cup containing a small piece of phosphorus, 
 which is placed in a dish of water; the phosphorus is then 
 ignited, and the cup covered by a bell-glass, or a glass shade, 
 the mouth of which is immersed in the water. The phos- 
 phorus, in burning, combines with the oxygen of the air 
 enclosed in the glass, producing phosphoric acid, and when 
 all the oxygen is removed by the phosphorus, or has entered 
 into the fresh combination, the phosphorus ceases to burn in 
 the absence of oxygen ; the water in the mean time, by the 
 removal of the volume of the oxygen, ascends in the glass. 
 The gas underneath the bell, after the operation, is nearly 
 pure nitrogen, and the bulk will be found to be diminished 
 about one-fifth ; this decrease of volume being due to the 
 absence of the oxygen which formerly existed, which has 
 entered into the composition of the flakes of phosphoric acid, 
 and become absorbed by the water. 
 
 Carbon . — This is, likewise, one of the most abundant 
 elements, and is extensively distributed in nature as a consti- 
 tuent of all animal and vegetable bodies. It exists in the 
 mineral kingdom in various forms — very largely in the state 
 of coal. It also enters into the composition of some earthy 
 bodies; for, united with lime, it forms marble, chalk, and 
 limestone. The diamond, although unlike any of the sub- 
 stances named, is pure carbon, and is about three and a half 
 times heavier than water. 
 
 The carbonaceous incrustation in retorts, the soot produced 
 
36 
 
 ON TI1E CHEMISTRY OF GAS-LIGHTING. 
 
 by the imperfect combustion of oil or gas, lampblack, and 
 charcoal, are all carbon, more or less impure. 
 
 Under ordinary temperatures, carbon has no affinity for 
 oxygen, nor is carbon affected by heat, unless oxygen, nitro- 
 gen, and a few other substances be present. Thus, the diamond 
 remains unaltered in the hottest furnace if these bodies are 
 excluded ; but if oxygen is present, it will combine with it 
 to form carbonic acid at a comparatively low temperature. 
 
 The combustion of carbon in air or oxygen, produces 
 light, more or less brilliant, according to the degree of heat 
 to which it is raised. 
 
 Carbon alone is never found in the gaseous state, but 
 Several gases have the power of combining with it, and con- 
 ferring on it that property ; but as soon as the combinations 
 are destroyed by the abstraction of the other gaseous body, 
 the carbon again becomes solid : a most important property, 
 which requires especial attention in connection with the 
 combustion of gas. 
 
 Sulphur , — This exists in large quantities in nature, form- 
 ing part of the ores of copper, lead, mercury, silver, and 
 other metals. It also issues from volcanoes, in the form of 
 gases, in great abundance, and in its solid state is well known 
 under the name of brimstone. It exists in coal in the bright 
 metallic laminae which intersect it, these being chiefly a com- 
 pound of sulphur and iron. Coke, even after having been 
 submitted to a very protracted and high heat, still contains a 
 portion of sulphur, giving rise to the noxious odour occasioned 
 by burning it in confined places. A highly volatile com- 
 pound of sulphur and carbon is produced in the distillation 
 of coal by the combination of a certain amount of sulphur, 
 with carbon, viz. the bisulphide of carbon. 
 
 The peculiar, disagreeable odours of many of the com- 
 pounds of sulphur are familiar to all, and are the most 
 troublesome of all the impurities of coal gas, the economical 
 removal of which has for several years defied the chemist’s 
 skill. 
 
COMBINATION OF THE ELEMENTS. 
 
 37 
 
 COMBINATION OF THE ELEMENTS. 
 
 Having briefly given a description of the various elements 
 in chemistry which immediately interest the gas manufac- 
 turer, I will now enter on their combinations to form coal 
 gas, its impurities, and the results of its combustion. 
 
 By a law of nature all elements have, in their most 
 minute particles or atoms, an innate attraction for certain 
 others, with which they combine and form compounds. This 
 by chemists is called affinity, and by this law of affinity 
 oxygen and hydrogen combine and form water — these gases 
 in like manner, by the intervention of the electric spark or 
 fire, unite to compose the same liquid. By affinity, carbon 
 combines with oxygen, producing carbonic oxide and carbonic 
 acid. Sulphur combines with hydrogen, and the result is sul- 
 phuretted hydrogen. Nitrogen combines with hydrogen, and 
 ammonia is produced. And by this affinity all the various 
 compounds or substances in nature are held together. 
 
 For the sake of brevity and general elucidation, chemists 
 have devised a very simple means of describing compounds, 
 and at the same time to express their constituent and quan- 
 titive parts. For this purpose instead of writing or naming 
 the elements in full, abbreviations are employed, which are 
 frequently the capital initial letter of the element to be 
 expressed ; or when there are two or more with the same 
 initial, then a second small letter is added to make the requi- 
 site distinction. In those under notice the initial only is 
 employed, thus — oxygen is expressed, 0 ; hydrogen, H ; 
 nitrogen, N ; carbon, 0 ; sulphur, S ; and these are called 
 the symbols of their respective elements. Of course all the 
 others have their corresponding symbols. 
 
 Whenever elements combine with each other it is only 
 in a particular and definite manner, which is called their 
 combining quantities or proportions, and this occurs by 
 weight and by volume, which bear a direct relation to each 
 other. 
 
38 
 
 COMBINATION OF THE ELEMENTS! 
 
 The elements named combine by weight only in the 
 following proportions, or their multiples : — 
 
 These numbers are called the equivalents of their respec- 
 tive elements. 
 
 When gases combine it is always by measures, which bear 
 a simple relation to each other in the following propor- 
 tions : — thus, hydrogen combines with oxygen in the pro- 
 portion of two volumes or bulks of the former with one 
 volume or bulk of the latter gas ; hydrogen and sulphur in 
 like proportions ; nitrogen and hydrogen in the proportion of 
 one to three ; &c. 
 
 The chemical expression, or, as termed, formula, of the 
 composition of water is H 2 0, signifying two atoms or equiva- 
 lents of H (hydrogen), combined with an atom of 0 (oxygen). 
 As already stated, hydrogen constitutes by weight one-ninth 
 part of w T ater, and by volume two -thirds ; whilst oxygen by 
 weight constitutes eight-ninths, and by volume one-third ; 
 giving a simple illustration of the combining proportions by 
 weight and volume. 
 
 In order to give examples of the combination of the 
 elements to form compounds, and the formula employed : 
 — One equivalent or atom of carbon, combined with an 
 atom of oxygen, form carbonic oxide, expressed by the for- 
 mula 0 0. One atom of carbon with two of oxygen, 
 expressed 0 0 2 , constitutes carbonic acid. One equivalent 
 or atom of nitrogen with three atoms of hydrogen, formula 
 N H 3 , produces ammonia. By these means the various com- 
 pounds of gases are formed and expressed. 
 
 The means of ascertaining the specific gravity or weight 
 of gas is ascertained in the simplest manner with the balloon 
 made by Mr. WTight, which is treated on in the chapter 
 devoted to experiments on coal gas. 
 
 Hydrogen 
 
 Oxygen 
 
 Carbon 
 
 Sulphur 
 
 Nitrogen 
 
 1 
 
 16 
 
 12 
 
 32 
 
 14 
 
COMPOSITION OF COAL GAS. 
 
 39 
 
 COMPOSITION OF COAL GAS. 
 
 Coal gas when purified is composed chiefly of carbon and 
 hydrogen, and consists principally of a definite compound 
 called light carburetted hydrogen, or marsh gas, combined 
 with a variable mixture of vapours or gases consisting of 
 carbon and hydrogen, called heavy hydrocarbons, the most 
 important of which is known as olefiant gas ; carbonic oxide 
 is also one of its constituents. The impurities are sulphu- 
 retted hydrogen, ammonia, nitrogen, carbonic acid, and bisul- 
 phide of carbon. 
 
 Light carburetted hydrogen , or marsh gas, is a compound 
 of carbon and hydrogen, in the proportion of one atom of 
 the former to four atoms, of the latter, its chemical formula 
 being 0 H 4 . It is this compound which constitutes the 
 inflammable fire-damp of coal mines, where it is generated 
 spontaneously ; it proceeds abundantly from the decompo- 
 sition of vegetable substances, and is one of the products of 
 the distillation of coal. 
 
 This gas is colourless, nearly inodorous, and does not 
 affect vegetable colours, and, like hydrogen, is permanently 
 gaseous under intense cold or pressure. It is highly com- 
 bustible in oxygen or air, and explosive to a violent degree 
 if mixed with either of these in the due proportion necessary 
 to convert all the hydrogen into water, and the carbon into 
 carbonic acid. In proportion as the oxygen exceeds or falls 
 short of that quantity, so is the explosive power decreased. 
 
 By weight marsh gas contains 12 parts of carbon and 
 4 parts of hydrogen, or, 100 parts contain — 
 
 Carbon . .75 
 
 Hydrogen . . 25 
 
 Its density is '559 (air being 1000), the weight of 100 
 cubic inches being 17*41 grains. 
 
 To obtain this gas, a mixture of 40 parts of crystallised 
 acetate of soda, 40 parts of solid hydrate of potash, and 
 60 parts of quicklime in powder, is transferred to a flask 
 or retort, and strongly heated, when the gas is disengaged in 
 great abundance. 
 
40 
 
 COMPOSITION OF COAL GAS. 
 
 When marsh gas is burned in the air, if allowed to issue 
 as a large, thick flame, considerable light is obtained ; it is 
 possible, however, to burn it without any appreciable light, 
 by causing it to issue, under great pressure, from very 
 minute orifices ; but this peculiarity of burning, with or 
 without the emission of light, according to the circumstances 
 attending the combustion, exists with all the gaseous com- 
 pounds of carbon and hydrogen. 
 
 Pure carburetted hydrogen gas may be respired with 
 safety. The unpleasant smell of common coal gas is due to 
 impurities. In its natural forms of marsh gas and fire-damp, 
 it is generally contaminated with nitrogen, and with a small 
 proportion of carbonic acid gas. 
 
 Grains. 
 
 A cubic foot of this gas weighs . ... 300 
 
 And requires for its combustion 2 cubic feet of oxygen . 1200 
 
 1500 
 
 The products are 1 cubic foot of carbonic acid, weighing 817 
 
 Water . . . 683 
 
 1500 
 
 Olefiant gas , or oil-making gas, is so named from its forming 
 an oil when combined with chlorine or bromine. It consists 
 of two atoms of carbon united to four atoms of hydrogen, its 
 formula being C 2 H 4 ; hence by weight 100 of olefiant gas 
 contain 85*7 carbon and 14*3 hydrogen. Its density is *981, 
 and the weight of 100 cubic inches 30*57 grains. 
 
 Olefiant gas containing double as much carbon as the 
 light carburetted hydrogen, burns with much greater bril- 
 liancy, and gives out a very superior light. 
 
 This gas may be obtained from alcohol, by mixing with it 
 five or six times its weight of sulphuric acid, placing this in 
 a glass retort, and by the gentle application of heat, the gas 
 distils over, which may be afterwards purified from carbonic 
 acid by agitation with solution of caustic potash. Olefiant 
 gas is combustible and explosive under similar circum- 
 stances to light carburetted hydrogen, requiring, however, 
 two volumes more oxygen. 
 
COMPOSITION OF COAL GAS. 
 
 41 
 
 There are other heavy hydrocarbons which enter into the 
 composition of coal gas, having the same nature as olefiant 
 gas, known as propylene, butylene, &c. ; these, with the 
 general constituents of coal gas and its impurities, have been 
 very ably treated on in a lecture delivered by Dr. Letheby, 
 and recently published in the Journal of Gas Lighting , to 
 which the attention of the reader is especially directed. Ole- 
 fiant gas is decomposed by passing it through a tube heated 
 to bright redness ; a deposit of carbon takes place, and the 
 gas becomes converted into light carburetted hydrogen. If 
 the operation be performed with increased heat, the whole 
 of the carbon is deposited, leaving the hydrogen free. This 
 illustrates very forcibly the deterioration of coal gas by the 
 deposit of carbon in the retorts. 
 
 Hydrocarbons . — Coal gas, according to the description of 
 coal from wdiich it is produced, and the mode of distillation, 
 contains from 3 to 30 per cent., by volume, of vapour or 
 gaseous matter (carbon and hydrogen), to which the general 
 name of hydrocarbons is applied ; and the illuminating 
 power of gas is in direct proportion to the quantity of hydro- 
 carbon in combination therewith. 
 
 If chlorine, bromine, or dry sulphuric acid, be added to a 
 sample of coal gas, or if the gas be subjected to excessive 
 pressure or extreme cold, the heavy hydrocarbons are depo- 
 sited in the form of oil, the volume of the gas being sensibly 
 diminished in proportion to the quantity condensed. 
 
 Dr. Fyfe has for a long period devoted his talents in order 
 to arrive at a positive law, so as to be enabled to estimate the 
 illuminating power of gas by the quantity condensed by 
 chlorine ; and more recently Mr. Lewis Thompson has 
 employed bromine for the same purpose. But by these 
 means the volume only of the heavy hydrocarbons is ascer- 
 tained ; and as a knowledge of their density is essential, and 
 is not obtained by this process, therefore this mode of testing 
 can only give comparative, but not absolute, results. 
 
 Messrs. Faraday and Coombe have also attempted to define 
 the illuminating power of gas by condensing the hydro- 
 carbon under great pressure, the density of which being 
 ascertained, the value of the gas was estimated accordingly ; 
 
42 
 
 COMPOSITION OF COAL GAS 
 
 but the delicate manipulation would prevent the general 
 application of this operation. 
 
 Formerly much importance was attached to the specific 
 gravity of gas as an indication of its value ; and it is still 
 the opinion of some eminent chemists, that when gas is free 
 from impurities, this mode of ascertaining its quality or 
 illuminating power is worthy of the greatest reliance. 
 
 Dr. Henry was the first to indicate the evaluation of gas 
 for illumination, by estimating the quantity of carbon con- 
 tained in the condensable portions thereof. 
 
 Carbonic oxide , or the protoxide of carbon, consists of one 
 atom of carbon and one of oxygen, its atomic weight being, 
 carbon 12 + oxygen 16 = 28, its formula being 0 O. Hence 
 it contains by weight of 43 per cent, of carbon, and 57 per 
 cent, of oxygen. Carbonic oxide is prepared in the labora- 
 tory by passing carbonic acid over red-hot charcoal or 
 metallic iron, by which half its oxygen is removed, and 
 becomes converted into carbonic oxide. This change also 
 explains the mode of its formation in the process of distilling 
 coal for gas-making purposes. Carbonic oxide contains half 
 its volume of oxygen, is a combustible gas, and burns with a 
 beautiful blue flame, the product of combustion being car- 
 bonic acid. This gas is extremely poisonous, even worse 
 than carbonic acid, is colourless, and possesses very little 
 odour. Its specific gravity is *968, the weight of 100 cubic 
 inches being 30 grains. 
 
 This compound exists more or less in coal gas, but seldom 
 exceeding 10 per cent, by volume, and generally much less. 
 It requires one volume of oxygen for combustion, being then 
 converted into carbonic acid. 
 
 Carbonic oxide contributes to the heat of the flame, but 
 only indirectly to the light. It is not considered an impurity 
 in coal gas ; although the fact of it giving off less heat than 
 hydrogen, whilst it absorbs the same quantity of oxygen, and 
 produces one volume of carbonic acid (a substance always 
 very objectionable), undoubtedly renders it an impurity. 
 
 Coal gas often contains a trace of free nitrogen and oxygen ; 
 but these, by the best analysis, are generally in about the 
 proportion required for atmospheric air. This is therefore 
 
IMPURITIES OF COAL GAS. 
 
 43 
 
 probably due to the admission of air either when changing 
 the purifiers or by undue exhaustion. 
 
 IMPURITIES OF COAL GAS. 
 
 Sulphuretted hydrogen (hydro-sulphuric acid). — This com- 
 pound consists by weignt of one part of hydrogen gas and 
 sixteen parts of sulphur vapour, its atomic weight being 
 H 2 + S 32 = 34, and expressed by the chemical formula 
 H 2 S. By measure it contains two volumes of hydrogen, 
 combined with one volume of the vapour of sulphur, the two 
 being condensed into two volumes. The specific gravity of 
 this impurity is greater than common air, being 1T78. The 
 weight of 100 cubic inches is 36*51 grains. 
 
 Sulphuretted hydrogen may be produced for experiments 
 by putting some iron pyrites (a compound of sulphur and 
 iron) and dilute sulphuric acid into a glass retort ; heat 
 ■being applied, gas is disengaged, which is caused to pass 
 through water, when pure sulphuretted hydrogen is 
 obtained. This is a colourless gas, possessing acid properties, 
 reddening litmus paper, and has a most offensive odour, similar 
 to putrid eggs, which indeed contain it ; it is very poisonous, 
 and if breathed into the lungs is injurious to life, occasioning 
 suffocating vapours like those arising from the burning of 
 brimstone ; it tarnishes metals, changes the colour of most 
 kinds of paint and furniture hangings ; and when coal gas 
 possessing this impurity is burned, the sulphur combines 
 with the oxygen of the atmosphere, forming sulphurous 
 acid. Therefore, with all the various evils enumerated, it 
 is of the utmost importance that gas should be entirely free 
 from it, and any establishment neglecting this does a serious 
 injury to its business, as well as to the comforts of gas con- 
 sumers. 
 
 Sulphuretted hydrogen is removed from coal gas by means 
 of lime in solution, the “ milk ” or “ cream ” of lime, as in the 
 wet-lime purifiers ; or by means of the hydrate of lime (lime 
 slackened and moistened), as in the dry -lime purifiers; or by 
 the oxide of iron, muriate of manganese, &c. The incon- 
 
44 
 
 IMPURITIES OF COAL GAS. 
 
 venience occasioned by the lime purification, in consequence 
 of the odour emanating therefrom, also the difficulty of 
 disposing of the waste material, has of late years caused 
 the use of oxide of iron to become very general ; and per- 
 haps the economy attending it may have been an induce- 
 ment. When dry lime is used it is necessary to have the 
 lime greatly in excess, as it ceases to absorb sulphuretted 
 hydrogen long before it becomes saturated. The absorbing 
 action of the lime is said to be much increased by adding 
 hydrous sulphate of soda : this has been proposed by Professor 
 Graham ( Phil . Mag., June, 1841), who states that on the 
 addition of the sulphate of soda the action Continues till two 
 equivalents of sulphuretted hydrogen have been absorbed by 
 one equivalent of lime. The lime is entirely converted into 
 gypsum, or sulphate of lime, and the whole of the soda 
 becomes bi-hydro-sulphuret of soda, which might easily be 
 washed out of the lime : this bi-hydro-sulphuret may be 
 readily again converted into soda by roasting it, and thus 
 might be used over and over again to mix with the lime in 
 the purifiers. 
 
 Nearly all coal contains more or less sulphur — usually in 
 combination with iron, and sometimes with lime in the form 
 of sulphuret of iron (iron pyrites) — or the sulphuret of 
 lime. During the process of distillation these sulphurets are 
 decomposed, part of the sulphur being driven off in vapour 
 or gas, and combining with hydrogen, the product being 
 sulphuretted hydrogen. Previously to purification about 8 
 feet of sulphuretted hydrogen exist in every 1,000 feet of 
 gas obtained from Newcastle coal. 
 
 The presence of sulphuretted hydrogen in gas is ascer- 
 tained by moistening a piece of unsized white paper with a 
 solution of the acetate of lead, and allowing a stream of gas 
 to impinge upon it, when, if present, the paper is immediately 
 darkened, or blackened, in proportion to the quantity of 
 impurity in the gas. 
 
 Carbonic acid is another well-known oxide of carbon, con- 
 taining two equivalents of oxygen to one of carbon. Its 
 chemical composition is denoted by the formula 0 0 2 ; its 
 atomic weight being C 12 + 0 2 32 = 44, and proportions 
 
IMPURITIES OE COAL GAS. 
 
 45 
 
 being 72*73 per cent, of oxygen, and 27*27 per cent, of 
 carbon. This gas is readily procured by decomposing any 
 of the earthy carbonates, as chalk or limestone, with a stronger 
 acid, which, forming a new 7 combination with the earthy base, 
 sets free the carbonic acid of the carbonate. Carbonic acid 
 gas is without colour, and though possessing an agreeable 
 pungent taste and odour, cannot be breathed for a moment 
 with impunity, as it rapidly produces the effect of suffocation, 
 insensibility, and death. This gas is familiar to us as the 
 fatal choke-damp of mines, as the fixed air in champagne, 
 
 . bottled beer, soda water, &c., and as the heavy gas which 
 floats over the large vats in breweries w 7 hile the beer is 
 undergoing the process of fermentation. It is also produced 
 wdierever there is combustion, and should always be carried 
 off by proper ventilation. 
 
 The specific gravity of this gas is 1*524, the w 7 eight of 100 
 cubic inches being 47*26 grains. Not only is this gas entirely 
 uninflammable, but it instantly extinguishes flame even wdien 
 diluted with three times its volume of air. The carbonic acid 
 gas, owing to its great affinity for lime, is readily separated 
 either by being exposed to the absorption of hydrate of lime, 
 or that of lime diffused through water, as in the w'et-lime 
 purifiers. It is extremely injurious in gas intended for illu- 
 minating purposes, as it tends directly to destroy combustion. 
 At the same time the great density of carbonic acid gas 
 would give to any compound containing it a false appearance 
 of value by exhibiting a high specific gravity, and hence its 
 presence may reasonably be expected in gas with feeble illu- 
 minating pow 7 er and considerable density. 
 
 Grains. 
 
 According to Dr. Henry, a cubic foot of carbonic oxide weighs 520 
 And requires for its combustion half a cubic foot of oxygen, 
 weighing . 300 
 
 The product being carbonic acid 
 
 820 
 
 The presence of this impurity in coal gas is detected by a 
 solution of lime in w 7 ater, which must be filtered till quite 
 clear ; a portion of which is put into a large test-tube, or 
 wine-glass, and by means of a flexible tube the gas under 
 examination is allowed to bubble through it for about one oi 
 
46 
 
 IMPURITIES OF COAL GAS. 
 
 two minutes ; if the water becomes cloudy or milky, it is a 
 proof of the presence of carbonic acid. 
 
 The rationale of this test is that lime is soluble in water, 
 but the carbonate of lime or chalk produced by the action of 
 the carbonic acid and lime is insoluble, and the cloudy appear- 
 ance indicates the production of the carbonate of lime. 
 
 Ammonia is produced during the distillation of coal by the 
 union of hydrogen with the azote or nitrogen which is con- 
 tained in coal, as in all other organic substances. In forming 
 ammonia, one atom of nitrogen unites with three atoms of 
 hydrogen, the chemical formula being NH 3 = 17*06, and 
 the proportions by weight being 82*41 per cent, of nitrogen, 
 and 17*59 per cent, of hydrogen. The density of ammonia 
 is *589, the weight of 100 cubic inches being 18*26 grains. 
 Two volumes of ammonia contain by measure three volumes 
 of hydrogen and one of nitrogen, the whole being condensed 
 to the extent of one-half. Ammonia is produced abundantly 
 in nature from the decomposition of animal and vegetable 
 substances : the gas is colourless and very pungent, acting 
 strongly on the mucous membrane of the nose, eyes, and 
 throat. A great part of the ammonia is separated from gas 
 by the condensing apparatus, combined with water, and called 
 ammoniacal liquor. The ammoniacal liquor is the principal 
 source from which ammonia is procured ; and numerous 
 patents have been taken out for improvements in the mode 
 of treating this liquor, in order to effect the production of 
 carbonates, muriates, and other salts of ammonia. The value 
 of ammoniacal liquor as a manure for top-dressing grass lands, 
 and in other applications, has been much insisted on of late 
 years, When diluted with four times its bulk of water and 
 applied by means of cylinder carts or other contrivances for 
 distributing liquid manure, the effect is said to be highly 
 beneficial. 
 
 Although the ammoniacal liquor is at present the only 
 source of ammonia in ordinary gas-works, there are other 
 parts of the purifying process in which it may be separated, 
 but not in sufficient quantities to be worth working. Where 
 the breeze condenser is used, certain volatile oils together 
 with ammonia are arrested ; also where dry lime is used for 
 
IMPURITIES OF COAL GAS. 
 
 47 
 
 purification, some volatile salts of ammonia are absorbed, and 
 certain carbonates and sulphates of ammonia are decomposed, 
 and the ammonia is set free. 
 
 Ammonia has strong alkaline properties, and its presence 
 is detected by moistened turmeric paper, which, when exposed 
 to the action of this gas, changes from its yellow colour to a 
 deep red or brown. It is also detected by reddened litmus 
 paper, which changes to blue. But the most minute quantity 
 that may be present is ascertained by filling a glass flask with 
 the gas to be examined, and inserting into it a glass rod 
 previously dipped into muriatic acid, when, if present, a white 
 cloud is formed in the flask — this being the muriate of 
 ammonia. 
 
 Formerly the ammoniacal liquor of gas-works possessed 
 but little value on account of the large quantity of water 
 intermixed with it, and in some cases where pure water was 
 used for the scrubbers, the greater portion of ammonia was 
 entirely lost ; but at the present day the ammoniacal liquor 
 from the condensation is made the medium of purification by 
 being pumped continuously through the scrubbers, until, by 
 the absorption of ammonia, it attains the desired specific 
 gravity, so to render it a valuable commercial commodity 
 Sometimes acidulated water is employed in the scrubbers to 
 remove the ammonia. 
 
 Ammonia in small quantities is not injurious to health, but 
 it acts on some of the metals, as brass and copper of the 
 fittings and meters, and is so far an impurity. Against this, 
 it converts any sulphuric acid formed during combustion into 
 sulphate of ammonia ; therefore in this respect it is beneficial, 
 and must be considered so until means are devised of freeing 
 gas from all its sulphur compounds. A very small quantity 
 intermixed with the gas is also considered essential, to 
 prevent the deposition of naphthaline in the pipes. 
 
 Ammonia is a gaseous body, and that which is usually 
 called so in the liquid state is ammoniacal gas intermixed 
 with water, which takes up or absorbs about 700 times its 
 own volume of that gas. 
 
 Bisulphide of carbon . — This impurity in coal gas until 
 recently attracted very little attention, but it is now found to 
 
48 
 
 IMPURITIES OF COAL GAS 
 
 be most objectionable on account of its very disagreeable 
 odour, its injurious effects, and the difficulty in removing it. 
 
 This gas is a compound of one equivalent of carbon and 
 two equivalents of sulphur, or by weight carbon 6, sulphur 
 32 = 38 ; its formula is C S 2 . It forms whenever sulphur 
 comes into contact with red-hot charcoal or coke. 
 
 No practical method has yet been generally adopted for 
 avoiding this obnoxious compound in coal gas ; the sub- 
 stances which have hitherto been employed for the purpose, 
 have at the same time deprived the gas of a portion of its 
 heavy hydrocarbons, and in consequence its illuminating 
 power has been much deteriorated. But there is reason to 
 believe that Mr. Leigh, chemist of the Manchester Gas Com- 
 pany, after some years’ labour, has succeeded in attaining 
 the desired object. 
 
 A means of preventing to a great extent the formation of 
 this substance is by distilling coal at a moderate heat, and not 
 allowing the charge to be quite exhausted. A few words of 
 explanation will make this palpable. Whenever coke is 
 burned in a confined place, the odour of sulphur is very 
 manifest, and is one of the great objections against the more 
 general usage of this fuel for domestic purposes; proving 
 that after the more volatile gases are disengaged, sulphur 
 must be in combination with the coke or carbon in the 
 retort, and the formation of the bisulphide of carbon is only 
 a natural result. 
 
 The means of detecting the presence of this impurity is by 
 passing the gas through a solution of potash and alcohol — 
 when, if present, the liquid, after standing in a cool situation, 
 deposes yellow needle-shaped crystals. The most delicate test 
 known to chemists at present consists in an ethereal solution 
 of Triethylphosphine, discovered some years ago by Dr. 
 Hofmann, which precipitates the merest trace of C S 2 in the 
 form of beautiful red needles. Apparatus hereafter explained 
 is also very generally employed in gas-works for the purpose 
 of indicating the presence of the compounds of sulphur. 
 
 Bisulphide of carbon may be produced by heating to red- 
 ness, in a close porcelain vessel, some iron pyrites, with one- 
 fifth of its weight of well-burned and dry charcoal. It may 
 
COAL USED IN GAS MAKING. 
 
 49 
 
 be condensed as a colourless liquid, having an acid taste and 
 very offensive odour, which vaporises with great facility, is a 
 remarkable solvent for india-rubber, and boils at 116° Falir. 
 
 Cyanogen . — The property of nitrogen to unite with carbon 
 and form cyanogen has been much studied. Cyanogen is an 
 inflammable gas, burning with a beautiful purple or peach- 
 blossom coloured flame, generating carbonic acid, and setting 
 nitrogen free. It contains one equivalent of carbon and one 
 of nitrogen, its atomic weight being 26, ' and the formula 
 
 C N. 
 
 Cyanogen exists in considerable quantities in the ammo- 
 niacal liquor ; and the separation of the cyanides for the 
 purpose of forming cyanide of potassium, prussiate of potash, 
 Prussian blue, and other compounds, engaged at one period 
 the serious attention of scientific men, but did not realise 
 their expectations. This s compound is not generally classed 
 amongst the impurities of coal gas, but as some chemists of 
 ability have decided it to be an impurity, for that reason it is 
 mentioned here. 
 
 CHAPTER III. 
 
 COAL USED IN GAS MAKING. 
 
 Although there are many substances, such as wood, tallow, 
 oil, resin, &c., from which gas for illumination can be 
 obtained, but as these, on account of their increased cost, 
 are very rarely used, it will answer all the purposes of the 
 present treatise by confining myself simply to coal as the 
 means of obtaining gas. 
 
 The origin of this mineral is involved in some doubt, but 
 the theory generally admitted by geologists is, that its forma- 
 tion was caused by the deposit of vegetable matter, which 
 in the course of ages became converted into coal. Some 
 eminent geologists suppose coal beds to have been originally 
 a kind of peat bog, or immense accumulations of masses of 
 
 D 
 
50 
 
 COAL USED IN GAS MAKING. 
 
 vegetable remains, and that subsequently the tracts of country 
 where they existed, by some extensive convulsions of the 
 earth, subsided below their former level, and were covered 
 by various deposits. Others suppose that the trees of pri- 
 meval forests were carried away by floods and rivers, and 
 deposited in immense lakes, where afterwards they were 
 covered by mud, sand, argile, and such like substances, so 
 constituting the covering strata. It is further conjectured 
 that the vegetable remains, whether of 'trees, peat, moss, 
 &c., being thus buried, became after many ages converted 
 into coal, and the deposits were converted into rock, shale, 
 schist, marl, &c., which now intersect and cover the various 
 strata of coal. 
 
 This assumption is formed from the fact that in all coal 
 there are traces of vegetation, as ferns, and even the trunks 
 of trees ; these are so positive in their form and appearance, 
 often with the bark attached, as to leave no doubt of their 
 origin. This is particularly the case with the Boghead 
 Cannel, wherein the trunks and branches of trees are often 
 found, the wood having the nature of that coal, and the bark 
 resembling the caking coal. 
 
 There are various other theories which have their sup- 
 porters, and perhaps one of the most feasible is the supposi- 
 tion that coal was formerly a deposit of carbonaceous liquid 
 similar to petroleum, and that by crystallisation this liquid 
 became coal, such as we find it. Those of this opinion argue 
 that the presence of trees and vegetation might have been 
 accidental, or probably by the design of Providence, in order 
 to assist in the crystallisation of the mass. 
 
 The use of coal is comparatively of modern date, for the 
 first colliery was opened in the high grounds in the neigh- 
 bourhood of ISfewcastle-on-Tyne in the year 1238. About 
 1306 coal was employed in London by brewers, dyers, and 
 other branches of industry which required large fires ; but 
 the smoke produced from it became so offensive to the resi- 
 dent nobility and gentry, that they remonstrated against 
 its use, and, in consequence, a Royal proclamation was 
 issued, forbidding in London the use of coal as fuel. Some 
 fow years afterwards, wood fuel becoming scarce, the nopu- 
 
COAL USED IN GAS MAKING. 
 
 51 
 
 lation and trade of the city increasing, prejudice gave way 
 to utility, and the force of the proclamation diminished. 
 
 The use of coal became afterwards very general, but the 
 extortion and abuse of the dealers therein was so excessive, 
 that by Act of Common Council of the City of London, in 
 1665, each of the city trades’ companies w T as ordered to lay 
 up large stores of coal in summer, which in winter was to be 
 vended to the poor at as low a price as possible, so as not to 
 sustain loss. 
 
 The first patent in conjunction with coal was granted in 
 1589, for the purpose of smelting iron therewith. Patents 
 were subsequently obtained at various periods, for obtaining 
 oil, pitch, tar, and making charcoal (coke) from coal. In 
 1781 a patent was granted to the Earl of Dundonald, for 
 “ a method of extracting or making tar, pitch, essential oils, 
 volatile alkali, mineral acids, salts, and cinders from pit coals.” 
 By this it will be observed, that although the patentee was 
 well acquainted with most of the residues, or results of the 
 residues of the distillation of coal, yet the most valuable 
 constituent, the gas, was entirely lost sight of. A few years 
 after this (1791) a patent was obtained for using an ex- 
 plosive mixture of inflammable air (gas) combined with 
 atmospheric air, to produce motive power — an invention only 
 at the present day being carried practically into operation. 
 
 Dr. Thomson divides pit coal into three species : brown 
 coal, black coal, and glance coal. The brown coal is a kind 
 of lignite or imperfect coal found at Bovey Tracy in Devon- 
 shire, also in several parts of Ireland, France, Germany, 
 Iceland, &c. It contains a large quantity of bitumen, pro- 
 ducing volatile carburets when distilled : the texture is 
 fibrous, with evident marks of vegetable origin : it burns 
 with a bright flame, yielding a peculiar bituminous odour, 
 but does not occur in sufficient quantity to render it of much 
 importance in the manufacture of gas. 
 
 There are other classes of lignite which exist in many 
 parts of the world, called bituminous wood, earthy lignite, 
 and common lignite. Common lignite is of interest to the 
 gas manufacturer, on account of its strong resemblance to 
 coal, for which, by an inexperienced eye, it might readily 
 D 2 
 
COAL USED IN GAS MAKING. 
 
 53 
 
 be mistaken ; when distilled it gives off an abundance of 
 water, with a small yield of gas of low illuminating power, 
 possessing a most offensive sulphurous odour, which lime 
 purification does not remove. This material contains very 
 little tar, and the residue left in the retorts is simply breeze 
 in cubes. It is therefore useless for the manufacture of gas, 
 and only serviceable for burning lime, bricks, and other 
 out-door purposes. 
 
 The varieties of black coal are for the most part valu- 
 able for the purposes of the manufacture of gas. They are 
 divided by Dr. Thomson into four sub-species, — namely, 
 caking coal, splint coal, cherry coal, and cannel or parrot coal. 
 
 Caking coal, to which variety belong most of the North- 
 umberland and Durham coals, is so named from its melting, 
 by reason of which the separate particles become united to- 
 gether into one pasty mass or cake, which, when used in a 
 common fire-place, requires to be frequently broken up to 
 allow currents of air to penetrate and promote its combustion. 
 This coal is soft and easily broken, is very inflammable, and 
 burns with a lively flame, giving out more heat in an open 
 fire-place than most of the other kinds. 
 
 Splint coal, so called from its splintery fracture, is broken 
 with more difficulty than the caking coal, and requires a 
 higher temperature to light it. This is the best description 
 for making coke, and when used in furnaces gives out the 
 greatest amount of heat. To this variety belongs the greater 
 part of the coal used in South Wales for smelting the ores 
 of iron and copper. It is probably the best coal in England 
 for making coke for locomotive engines, and from the experi- 
 ments of Sir Henry de la Beche and Dr. Lyon Playfair, is 
 the coal which appears to be the best adapted for steam 
 boilers in the Navy. 
 
 Cherry coal is about the same hardness as- caking coal, and 
 is easily broken ; it is also easily lighted, and burns with a 
 bright flame. It burns out quickly, not caking at all, but 
 leaving fully 10 per cent, of ash, while the best Newcastle 
 caking coal leaves only per cent. 
 
 Cannel coal is harder and more compact than any of the 
 other varieties, and is frequently cut into ornaments, which 
 
COAL USED IN GAS MAKING. 
 
 53 
 
 are not inferior in lustre to jet : it is very easily kindled, 
 burns with a bright flame, and does not soil the bars of a 
 grate. Cannel coal is extensively obtained in Scotland, and 
 is also procured from Lancashire, from whence it is brought 
 to the London market, both for use in gas-works, and some- 
 times, though rarely, for domestic consumption, its cleanliness 
 and cheerful crackling mode of burning being its chief recom- 
 mendation. Cannel coal is largely exported for the purpose 
 of manufacturing gas ; the greatly increased light obtained 
 therefrom renders it a very desirable commodity, particularly 
 when the expenses of transport are great. 
 
 Glance coal or anthracite consists almost entirely of carbon, 
 and contains only a very small proportion of volatile con- 
 stituents. Although extremely valuable as a heat-giving 
 coal, it is almost worthless in the manufacture of gas. It 
 exists in great abundance in the western part of the South 
 Wales coal field, in Kilkenny, in Pennsylvania, and other 
 parts of the world. 
 
 All coals are composed nearly of the same ingredients, 
 which, however, vary considerably in their respective quan- 
 tities, to illustrate which a table of the analysis of a few 
 classes is subjoined : — 
 
 Locality, or Name 
 of Coal. 
 
 Specific 
 
 Gravity. 
 
 Car- 
 
 bon. 
 
 Hyd- 
 
 rogen. 
 
 Nitro- 
 
 gen. 
 
 Sul- 
 
 phur. 
 
 Oxy- 
 
 gen. 
 
 Ash. 
 
 Coke. 
 
 ( Thomas’s Merthyr . 
 
 1*30 
 
 90-12 
 
 4-33 
 
 1-00 
 
 •85 
 
 2- 02 
 
 1-68 | 
 
 86-53 
 
 o i Nixon's Merthyr . . 
 
 1*31 
 
 90-27 
 
 4-12 
 
 0-63 
 
 1-20 
 
 2-53 
 
 1-25 
 
 79 11 
 
 ^ Hill’sPlymouth works 
 
 1-35 
 
 88-49 
 
 4-00 
 
 0-46 
 
 0-84 
 
 3-82 
 
 2-39 | 
 
 82-25 
 
 0 /'Newcastle Hartley . 
 
 1-29 
 
 81-81 
 
 5-50 
 
 1-28 
 
 1-69 
 
 ' 2-58 
 
 7-14 
 
 64-61 
 
 | § i West Hartley Main . 
 tO 
 
 1-26 
 
 81-85 
 
 5-29 
 
 1-69 
 
 1-13 
 
 7-53 
 
 2 51 
 
 59-20 
 
 ^ V Hasting’s Hartley . 
 
 1-25 
 
 82-24 
 
 5-42 
 
 1-61 
 
 1*35 
 
 6-44 
 
 2-94 ! 
 
 35-60 
 
 The carbon in the composition of coal may either be fixed 
 or volatile ; by fixed carbon is understood that which does 
 not volatise when undergoing ordinary distillation, but re- 
 mains in the retort as coke. The volatile carbon is that 
 which passes off as gas, hydrocarbons, tar, &c. 
 
 The foregoing table demonstrates this difference very 
 
54 
 
 COAL USED IN GAS MAKING. 
 
 forcibly, for in the Welsh coal upwards of 90 per cent, remain 
 fixed as coke, and as a consequence, this class, although 
 admirably adapted for steam purposes, is useless for the 
 manufacture of gas. According to the same table, the 
 Hasting’s Hartley yields about 57 per cent, of volatile carbon, 
 which renders it a good gas-producing agent. But it must 
 be observed that the last mentioned material would, on 
 account of its volatility, be ill adapted for steam purposes, 
 as without the greatest care a large portion of it would pass 
 off as smoke. 
 
 The following table, by Mr. Lewis Thompson, and extracted 
 from the “ Journal of Gas Lighting,” gives the per-centage 
 of volatile matter in various coals : — 
 
 Per-centage of 
 volatile matter. 
 
 Boghead 684 
 
 Old Wemyss 52*5 
 
 Lesmahago 49'6 
 
 Arniston 45*5 
 
 Wigan 37-0 
 
 Newcastle Cannel 36 8 
 
 Caking Coals. 
 
 Heathern (Staffordshire) 429 
 
 Stavely (Derbyshire) 40'9 
 
 Silkstone (South Yorkshire) 343 
 
 Newcastle Gas Coals 27*8 to 31 '25 
 
 Coals are obtained very extensively in Belgium, France, 
 and other parts of the Continent, likewise in America and 
 Australia, and probably they exist in nearly every country in 
 the world, and even in many places beneath the depths of 
 the ocean. 
 
 For the combined purposes of producing good gas and 
 coke of excellent quality, possibly no mineral exists equal 
 to the caking coals of Newcastle-on-Tyne ; there is, however, 
 considerable variation in their respective natures ; some 
 classes having the superiority for the production of gas, 
 either in quantity or quality, while others give superior 
 coke, and gas of diminished value. 
 
 During the process of distillation this coal melts, forming 
 itself into a doughy consistency, and expanding considerably ; 
 but gradually, as the gas is expelled, it assumes a brittle 
 
COAL USED IN GAS MAKING. 
 
 55 
 
 homogeneous nature, and lias to be broken in order to 
 extract it from the retort. 
 
 The average yield of gas from a ton of Newcastle coal is 
 9,200 cubic feet, of a quality equal to about twelve candles, 
 that is, an argand burner with fifteen holes, consuming five feet 
 per hour, gives with this gas, a light equal to twelve sperm 
 candles, each consuming 120 grains per hour ; or, five feet of 
 gas is equal to 1,440 grains of sperm. With the production 
 stated the quality is seldom superior to this, but is often much 
 inferior. When retorts are heated to a moderate degree, 
 the volume of gas produced is less than that mentioned, but 
 its quality is improved. 
 
 A ton of caking coal yields, on the average, 13 J- cwts. of 
 coke. When the coal is distilled at a high temperature, the 
 coke is hard and brittle ; when distilled at a low temperature, 
 it is soft and friable. 
 
 If caking coal be exposed to the direct action of the atmo- 
 sphere, alike to sun and rain, its value as a gas and coke 
 producing agent is diminished in a most remarkable manner, 
 and the results of many observations justify the writer in 
 asserting that coal, when extracted from the mine, and so 
 exposed for three months, becomes deteriorated in value 
 to the extent of about 10 per cent. Of course the subsequent 
 deterioration is in a very reduced proportion ; but under the 
 most favourable circumstances this class of coal diminishes in 
 value by prolonged storage. 
 
 Caking coal is generally very small, and when wetted, by 
 accident or otherwise, and stored away in that state, has a 
 great tendency to ignite spontaneously, which circumstance 
 has frequently occurred. Another inconvenience with wet 
 coal is, that when the retorts are charged, the water inter- 
 mixed therewith is rapidly converted into steam, and carries 
 off a large portion of the heat from the retorts, so facilitating 
 the production of an excess of tar and a diminished quantity 
 of gas ; and, on the authority of a late engineer of eminence, 
 the distillation of small wet coals invariably produces naptha- 
 line. These are sufficient reasons to cause every precaution 
 to be employed to guard against such contingency. 
 
 A very curious phenomenon occurs when coals are piled 
 
56 
 
 COAL USED IN GAS MAKING. 
 
 away and subjected to the action of the weather. In the 
 course of time the iron pyrites become decomposed, and the 
 sulphur distributes itself throughout the heap in regular strata 
 at some distance from each other, the inclination or “dip” 
 being about 30° to the horizon, and the strata running parallel. 
 When the pile is seen in section it presents a very remarkable 
 appearance. The cause of this spontaneous stratification must 
 be left to our philosophers and geologists to define. 
 
 For the purpose of producing very superior, or, as techni- 
 cally termed, “ rich ” gas, the cannel coal obtained in Scotland 
 and the North of England surpasses all other. There is, how- 
 ever, considerable variation between the numerous classes ; 
 but that called “Boghead” is the most extraordinary, a ton 
 of this coal produces 15,000 feet of gas of a quality equal to 
 thirty-six candles, it possesses no ammonia, and very little 
 sulphur ; but the coke resulting from it is useless, except, 
 perhaps, as a deodorising agent, for which purpose Mr. 
 Lewis Thompson recommended it. 
 
 The gas from Boghead is never commercially used alone, 
 but it is often intermixed, like that from the other cannels 
 hereafter mentioned, with “poor” gases from caking coal, in 
 order to bring their illuminating power to the required 
 standard. For this object the Boghead must be distilled in 
 separate retorts, otherwise its residue would deteriorate the 
 value of the coke produced from the other coal. 
 
 The coke from nearly every description of cannel retains 
 the form and size of the coal previously to distillation. In its 
 nature it is compact, and resembles charcoal, for which it is 
 often substituted abroad. This coke is sometimes used as 
 fuel for the furnaces ; but very often an inferior description of 
 coal is employed for the purpose, and the coke is sold. There 
 is a description of Wigan cannel, also Bamsay’s cannel, which 
 gives a coke very similar to the caking coal, enabling it to be 
 used as fuel for the furnaces, and it is generally a more market- 
 able commodity than the coke from other cannels. 
 
 The gas derived from most cannel coal is suitable for en- 
 riching the “ poorer” gases, and for the purpose, as a rule, the 
 best quality is generally the cheapest. Boghead, in consequence 
 of its extensive usage for extracting petroleum oil, has attained 
 
COAL USED IN GAS MAKING. 
 
 57 
 
 a very liigli price, and at present cannot be employed in 
 many places with advantage ; but wherever freights are high 
 it can be recommended. The other classes of cannel, as 
 Leshmahago, to produce the same result, require a larger 
 per-centage than Boghead. For instance, if we suppose the 
 standard of illuminating power of gas required to be increased 
 from twelve candle to fourteen candle gas, the additional 
 illuminating power would be obtained from an admixture of 
 about If per cent, of Boghead coal, whereas it would require 
 nearly 3 per cent, of Lesmahago, and, of course, a consider- 
 ably greater increase of the other inferior cannels. 
 
 The following tables on experiments of the quantities of 
 gas derived from various coals, together with their specific 
 gravity and the weight of gas in pounds, must be interesting 
 to all connected with gas-lighting : — 
 
 Experiments on the Quantities of Gas derived from Coal. 
 
 Description of coal. 
 
 Cubic 
 feet of 
 gas per 
 ton of 
 coal. 
 
 Specific 
 gravity of 
 the gas. 
 
 Weight 
 of gas 
 in lbs. 
 avoir- 
 dupois 
 per ton 
 of coal. 
 
 Authority. 
 
 NEWCASTLE COALS. 
 
 
 
 
 
 
 English Caking Coal . 
 
 8,000 
 
 •420 
 
 257 
 
 Dr. Fyfe. 
 
 Newcastle Coal . 
 
 11,648 
 
 *475 
 
 423 
 
 Mr. Joseph Hedley. 
 
 Pelaw, Newcastle . . 
 
 11,424 
 
 *444 
 
 389 
 
 Ditto. 
 
 Pelton, ditto . . . 
 
 11,424 
 
 •437 
 
 382 
 
 Ditto. 
 
 Blenkinsopp, Carlisle . 
 
 11,200 
 
 *521 
 
 447 
 
 Ditto. 
 
 Newcastle .... 
 
 8,500 
 
 •412 
 
 268 
 
 London, 1837. 
 
 
 
 
 
 
 f Quantity made in 
 
 Wall’s End, Newcastle 
 
 12,000 
 
 •490 
 
 450 
 
 
 | the revolving web 
 
 
 
 
 
 
 retort ; authority. 
 
 
 
 
 
 
 l Mr. Clegg. 
 
 Pelton 
 
 11,000 
 
 •430 
 
 363 
 
 > 
 
 
 Leverson 
 
 10,800 
 
 •425 
 
 353 
 
 
 
 Washington . , . . 
 
 10,000 
 
 *430 
 
 330 
 
 
 
 Pelaw 
 
 11,000 
 
 •420 
 
 355 
 
 
 Mr. Lewis Thomp- 
 
 New Pelton .... 
 
 10,500 
 
 •415 
 
 335 
 
 
 son, author of the 
 
 Dean’s Primrose 
 
 10,500 
 
 •430 
 
 347 
 
 
 ► “ Chemistry of 
 
 Garesfield .... 
 
 10,500 
 
 *398 
 
 321 
 
 
 Gas-Lighting,” in 
 
 Gosforth 
 
 10,000 
 
 •402 
 
 308 
 
 
 the “ Journal of 
 
 West Hartley . . . 
 
 10,500 
 
 •420 
 
 339 
 
 
 Gas-lighting.” 
 
 Hasting’s Hartley . . 
 
 10,300 
 
 •421 
 
 333 
 
 
 
 ' Blenkinsopp .... 
 
 9,700 
 
 •450 
 
 335 
 
 ) 
 
 
 D 3 
 
58 
 
 COAL USED IN GAS MAKING. 
 
 On the Quantities of Gas derived from Coal — continued. 
 
 
 
 
 1 
 
 Weight 
 
 
 
 Cubic 
 feet of 
 
 Specific 
 
 of gas 
 in lbs. 
 
 
 Description of coal. 
 
 gas per 
 
 gravity of 
 
 avoir- 
 
 Authority. 
 
 
 ton of 
 
 the gas. 
 
 dupois 
 
 ' 
 
 coal. 
 
 
 per ton 
 of coal. 
 
 
 NEWCASTLE COALS — 
 
 
 
 
 
 continued . 
 
 
 
 
 
 Berwick & Craister’s ) 
 Wall’s End . . . j 
 
 12,507 
 
 •470 
 
 449 
 
 Mr. Clegg. 
 
 Pelaw Main .... 
 
 12,400 
 
 •420 
 
 399 
 
 Ditto. 
 
 Russell’s Wall’s End . 
 
 12,000 
 
 *418 
 
 384 
 
 Ditto. 
 
 Ellison’s Main . . . 
 
 11,200 
 
 •416 
 
 357 
 
 Ditto. 
 
 Felling Main . . . 
 
 Pearith’s Wall’s End . 
 
 11,200 
 
 *410 
 
 351 
 
 Ditto. 
 
 11,147 
 
 *410 
 
 350 
 
 Ditto. 
 
 Dean’s Primrose . . 
 
 11,120 
 
 *410 
 
 349 
 
 Ditto. 
 
 Benton Main . . . 
 
 10,987 
 
 •400 
 
 337 
 
 Ditto. 
 
 Eden Main . . . . 
 
 1 0,400 
 
 •400 
 
 318 
 
 Ditto. 
 
 Heaton Main . . . 
 
 10,400 
 
 •410 
 
 326 
 
 Ditto. 
 
 Pelton 
 
 11,000 
 
 •430 
 
 
 Mr. F. J. Evans. 
 
 Leverson 
 
 10,800 
 
 •425 
 
 
 Ditto. 
 
 Pelaw 
 
 11,000 
 
 *420 
 
 
 Ditto. 
 
 Garesfield .... 
 
 10,500 
 
 *398 
 
 
 Ditto. 
 
 Gosforth 
 
 10,000 
 
 •402 
 
 
 Ditto. 
 
 Dean’s Primrose . . 
 
 10,500 
 
 •430 
 
 
 Ditto. 
 
 PARROT OR CANNEL 
 
 
 
 
 
 COALS. 
 
 
 
 
 ( Mr. J. Evans, at 
 
 Boghead Cannel . . 
 
 15,000 
 
 752 
 
 866 
 
 I Westminster Sta- 
 | tion of Chartered 
 1 Gas Company.* 
 
 Lesmahago, No. 1 . . 
 
 13,500 
 
 •642 
 
 666 
 
 Ditto. 
 
 Ditto No. 2 . . 
 
 13,200 
 
 *618 
 
 627 
 
 Ditto. 
 
 Capeldrae Cannel . . 
 
 14,400 
 
 •577 
 
 638 
 
 Ditto. 
 
 Arniston ditto . . 
 
 12,600 
 
 •626 
 
 606 
 
 Ditto. 
 
 Ramsay Cannel . . . 
 
 10,300 
 
 •548 
 
 433 
 
 Ditto. 
 
 Wemyss ditto . . . 
 
 14,300 
 
 •580 
 
 637 
 
 Ditto. 
 
 Kirkness ditto . . . 
 
 12,800 
 
 •562 
 
 552 
 
 Ditto. 
 
 Knightswood ditto . . 
 
 13,200 
 
 •550 
 
 558 
 
 Ditto. 
 
 Wigan (Ince Hall) ditto 
 
 11,400 
 
 •528 
 
 461 
 
 Ditto. 
 
 Wemyss Cannel . . 
 
 10,976 
 
 •670 
 
 563 
 
 Mr. Wright. 
 
 Ditto ditto . . . 
 
 10,192 
 
 •691 
 
 538 
 
 Ditto. 
 
 Wigan Cannel . . . 
 
 Knightswood Cannel . 
 Lesmahago Cannel ) 
 
 9,408 
 
 9,720 
 
 11,681 
 
 •478 
 
 *590 
 
 •540 
 
 344 
 
 439 
 
 483 
 
 Ditto. 
 
 Ditto. 
 
 Ditto. 
 
 1st experiment . ( 
 
 Ditto 2nd experiment 
 
 9,878 
 
 •650 
 
 492 
 
 Ditto. 
 
 * Each of the results given by Mr. Evans is the mean of three experiments. 
 
COAL USED IN GAS MAKING 
 
 59 
 
 On the Quantities of Gas derived from Coal — continued . 
 
 Description of coal. 
 
 Cubic 
 feet of 
 
 Specific 
 
 Weight 
 of gas 
 in lbs. 
 
 gas per 
 
 f. ravity of 
 
 avoir- 
 
 ton of 
 
 the gas. 
 
 dupois 
 
 coal. 
 
 
 per ton 
 
 
 
 of coai. 
 
 Authority. 
 
 PARROT OR CANNEL 
 
 coals — continued. 
 
 Ramsay’s Newcastle ) 
 Cannel . . . . j 
 
 Lesmahago Cannel . . 
 
 Welsh Cannel . . . 
 
 Wigan Cannel . . . 
 
 9,016 
 
 11,812 
 
 11,424 
 
 11,200 
 
 •604 
 
 •737 
 
 *737 
 
 *606 
 
 Ditto ditto 
 
 9,500 
 
 •580 
 
 Lochgelly Parrot 
 
 9,123 
 
 •567 
 
 Ramsay’s Cannel 
 
 9,333 
 
 •598 
 
 Ditto ditto . . 
 Wigan Cannel . . 
 
 Scottish Parrot . . 
 
 Ramsay’s Newcastle 
 Cannel . . . . 
 
 Yorkshire Parrot 
 Wigan Cannel . . 
 
 Ditto ditto . . 
 
 Scotch ditto . . 
 
 Ditto ditto . . 
 
 . 9,667 
 
 . 9,500 
 
 . 9,500 
 
 | 9,746 
 
 . 11,500 
 . 14,453 
 . 14,267 
 . 14,000 
 . 13,813 
 
 •731 
 f -460 
 \ to 
 [•520 
 •640 
 f -654 
 \ to 
 [ *580 
 
 •640 
 
 *610 
 
 •580 
 
 •500 
 
 417 
 
 638 
 
 645 
 
 520 
 
 422 
 
 396 
 
 427 
 
 541 
 
 357 
 
 Mr. Wright. 
 
 Mr. Joseph Hedley. 
 Ditto. 
 
 Ditto. 
 
 { Liverpool New Gas 
 and Coke Com- 
 pany. 
 
 Dr. Fyfe. 
 
 { J. Z. Kay, Manager 
 of Dundee Gas- 
 Works. 
 
 f Dr. Lessen, Dr. 
 •j Miller, and Mr. 
 [ G. H. Palmer. 
 
 Dr. Fyfe. 
 
 466 
 
 Ditto. 
 
 423 
 
 Ditto. 
 
 708 
 
 664 
 
 622 
 
 529 
 
 Dr. Fyfe. 
 Mr. Clegg. 
 Ditto. 
 Ditto. 
 Ditto. 
 
 DERBYSHIRE, WELSH, 
 STAFFORDSHIRE, AND 
 OTHER KINDS OF 
 COAL. 
 
 Derbyshire Deep Main 
 Brymbo 2-yard Coal 
 Powell Coal, 2 cwt. 
 charges every 5 
 
 hours 
 
 Powell Coal, cwt. 
 charges every 5 
 hours 
 
 9,400 
 
 8,880 
 
 10,165 
 
 8,250 
 
 •424 
 
 •463 
 
 •459 
 
 •470 
 
 308 Mr. Wright. 
 315 Ditto. 
 
 357 
 
 Ditto. 
 
 296 
 
 Ditto. 
 
60 
 
 COAL USED IN GAS MAKING. 
 
 On the Quantities of Gas derived from Coal — continued . 
 
 
 
 
 
 Weight 
 
 1 
 
 
 
 Cubic 
 feet of 
 
 Specific 
 
 of gas 
 in lbs. 
 
 
 Description of coal. 
 
 
 gas per 
 ton of 
 
 gravity of 
 the gas. 
 
 avoir- 
 
 dupois 
 
 Authority. 
 
 
 
 coal. 
 
 
 per ton 
 of coal. 
 
 
 DERBYSHIRE, WELSH, 
 
 
 
 
 
 STAFFORDS HIRE, AND 
 OTHER KINDS OF 
 
 
 
 
 
 coal — continued . 
 Bickerstaff, Liverpool 
 
 
 11,424 
 
 •475 
 
 415 
 
 Mr. Hedley. 
 
 Neath, South Wales 
 
 . 
 
 11,200 
 
 •468 
 
 401 
 
 Ditto. 
 
 Birmingham Gas 1 
 
 
 
 
 f Birmingham Gas 
 
 Company : Lump 
 
 Coal from West 
 Bromwich . . . 
 
 
 6,500 
 
 *453 
 
 226 
 
 -j Company. Parlia- 
 [ mentary return. 
 
 
 
 
 •455 
 
 227 
 
 f Birmingham and 
 
 West Bromwich 
 
 . 
 
 6,500 
 
 [ Staffordshire. Do. 
 
 Macclesfield . . . 
 
 
 6,720 
 
 
 
 
 Stockport . . . 
 
 Oldham Watergate 
 
 
 7,800 
 
 •539 
 
 322 
 
 Parliamentary return 
 
 and Wigan Cannel 
 mixed . . . . ^ 
 
 1 
 
 9,500 
 
 •534 
 
 388 
 
 Manchester. Do. 
 
 Ormskirk or Wigan ) 
 Slack \ 
 
 
 8,200 
 
 •462 
 
 290 
 
 f Liverpool, OldCom- 
 | pany. Do. 
 
 Low Moor mixed with j 
 two kinds of Slack j 
 
 i 
 
 8,000 
 
 •420 
 
 257 
 
 Bradford. Do. 
 
 
 
 
 •530 
 
 
 f Leeds Company. 
 
 Leeds Coal . . . 
 
 • 
 
 6,500 
 
 263 
 
 \ Parliamentary re- 
 l turn. 
 
 
 Cannel .and common ' 
 Coal mixed . . . , 
 
 1 
 
 8,000 
 
 •466 
 
 285 
 
 f Sheffield Company, 
 j Parliamentary re- 
 1 turn. 
 
 Derbyshire Soft Coal 
 
 . 
 
 7,500 
 
 •528 
 
 303 
 
 Leicester. Do. 
 
 Ditto ditto 
 
 
 7,000 
 
 *448 
 
 240 
 
 Derby. Do. 
 
 Ditto ditto 
 
 
 7,000 
 
 •424 
 
 227 
 
 Nottingham. Do. 
 
 Staffordshire . 
 
 
 
 
 
 
 South’s .... 
 
 
 10,933 
 
 •398 
 
 333 
 
 Mr. Clegg. 
 
 Second variety . . 
 
 . 
 
 10,667 
 
 •395 
 
 322 
 
 Ditto. 
 
 Third variety . . 
 
 
 10,667 
 
 •390 
 
 318 
 
 Ditto. 
 
 Fourth variety . . 
 
 
 9,600 
 
 •320 
 
 235 
 
 Ditto. 
 
 Forest of Dean . . 
 
 
 10,133 
 
 •350 
 
 271 
 
 Ditto. 
 
 Second variety . . 
 
 
 10,133 
 
 *360 
 
 279 
 
 Ditto. 
 
 Welsh Coal. 
 
 
 
 
 
 
 First variety . . . 
 
 
 10,000 
 
 •385 
 
 295 
 
 Ditto. 
 
 Second variety . . 
 
 • 
 
 10,133 
 
 •380 
 
 295 
 
 Ditto. 
 
COAL USED IN GAS MAKING. 
 
 Cl 
 
 In examining the foregoing tables, at first sight one is 
 struck with the apparent discrepancies, in trials on the same 
 coal, existing between the various experimentalists, and if a 
 reason could not be assigned for these, probably our faith in 
 their general accuracy might be shaken ; but taking into con- 
 sideration the imperfect apparatus employed thirty years back, 
 when many of these experiments were made, and other causes, 
 there is much to admire and little to object to. 
 
 Some few years ago the influence of the various degrees of 
 temperature of the retorts, in the production of gas, was not 
 so well understood as at present — low temperatures, small 
 retorts, and eight-hour charges were very common, and as a 
 consequence a comparatively small volume of gas was obtained, 
 with an increase of tar. Therefore it is to be assumed that 
 the variations existing in the quantities produced from the 
 same kind of coal, must l^ave arisen from the temperature of 
 the retort during the operation. Thus, if we refer to the 
 two trials of Lesmahago, by the late Mr. Wright, who was 
 a most careful experimentalist, we find a great difference in 
 the volume of gas produced, which, however, is compensated 
 as near as possible by the specific gravity of the gas. The 
 greater yield no doubt was derived from the increased tem- 
 perature of the retort. The low production of’ gas obtained 
 by some of the authorities very probably arose from the retort's 
 not being sufficiently heated, so that a portion of the hydro- 
 carbons were converted into tar. 
 
 The variation in the specific gravity recorded is by no 
 means remarkable, on account of the imperfect instrument 
 formerly used for ascertaining it. 
 
 The table serves as a guide of considerable importance to 
 the gas manufacturer ; it enables him to estimate the quantity 
 and quality of gas, and gives, by inference, the weight of 
 coke derived from each description of coal. It also enables 
 him to estimate the value of gases obtained from cannel coals, 
 and to determine the quantity from each class of cannel that 
 may be requisite to increase the illuminating quality of gas 
 from one standard to another. 
 
62 CARBONISATION OR DISTILLATION OF COAL. 
 
 CHAPTER IV. 
 
 MODE OF CARBONISING. — TEMPERATURE OF FURNACES. 
 
 EFFECTS OF VARIOUS TEMPERATURES ON THE PRODUCTION 
 OF GAS AND TAR. THE PROPER TEMPERATURE FOR RE- 
 TORTS. THE CHARGES OF RETORTS. FUEL IN HEATING 
 
 FURNACES. TAR AS FUEL. ON THE MODE OF WORKING 
 
 RETORTS. INCRUSTATION OF CARBON IN THE RETORTS. 
 
 MODE OF CLEANSING. 
 
 CARBONISATION OR DISTILLATION OF COAL. 
 
 The first process in gas manufacture consists in submitting 
 the coal to the action of a high heat, whereby its destructive 
 distillation, or as generally termed carbonisation, is effected. 
 In practice, this is don'e by placing the coal into retorts of 
 fire-clay or iron, which are previously heated considerably 
 above its point of ignition. 
 
 The retort being charged with coal, is then hermetically 
 closed with a door and luting, leaving no means of escape 
 for the gas, except through the ascension pipe. By these 
 means the coal is decomposed and the gas evolved, and when 
 effectually done the residue left in the retort is simply coke — 
 a substance chiefly consisting of carbon, containing neither 
 bitum.en, tar, nor other volatile matter capable of yielding a 
 useful gas for the purpose of lighting. 
 
 The gas expelled from the coal passes from the retort a 
 (Fig. 1), up the vertical pipe, called ascension pipe, c ; then 
 traverses the bridge, or H-pipe d, down the dip pipe e, into 
 the hydraulic main l — which is a large tube placed horizon- 
 tally, and extending along the length of the furnaces, b is 
 the mouth-piece attached to the retort; h is the lid or door 
 of mouth-piece ; j, the screw for securing the same ; f, the 
 furnace ; k, the furnace door ; and g the ash or evaporating 
 pan. 
 
 The hydraulic main is about half filled with water or tar, 
 into which the ends of each and all the dip pipes are im- 
 mersed, and the gas, as generated, forces its passage through 
 the liquid into the space above, but cannot again return into 
 
CARBONISATION OR DISTILLATION OF COAL. G3 
 
 Fig- 1. 
 
64 
 
 TEMPERATURE OF FURNACES. 
 
 the retorts; so that when once arrived in the hydraulic main, 
 it is fairly secured, and ready for the operation of purifica- 
 tion. 
 
 The reason of this is very simple — for the heat, in expel- 
 ling the gas from the coal, by the vastly increased volume, 
 creates a pressure or force similar to that of steam when 
 generated from water, the two processes being identical. 
 This pressure being superior to the obstacles which oppose 
 the passage of the gas, such as the dips of the hydraulic main, 
 scrubbers, purifiers, gasholder, and atmospheric pressure, the 
 gas in consequence passes freely as generated ; and the column 
 of liquid in the hydraulic main and dip pipe being consider- 
 ably greater than the pressure of the gas when in the holder, 
 it is thus prevented from returning to the retort. 
 
 In the manufacture of gas, the proper means of carbonising 
 coal is of the first importance ; ignorance on this point has 
 often entailed considerable and serious loss, when, by a little 
 intelligence, proportionate profits would have resulted. To 
 ensure the necessary degree of heat for the retort is of the 
 utmost consequence. 
 
 TEMPERATURE OF FURNACES. 
 
 With reference to the heat which it is proper to employ 
 in the distillation of coal for gas-making, it is unfortunate 
 that science has not yet furnished the practical man with any 
 convenient method of estimating high temperatures. Wedg- 
 wood’s pyrometer, though extremely ingenious, gives all its 
 indications on so small a base line as to require an accuracy 
 and homogeneity in the composition of the clay cylinders 
 employed which is physically impossible. The range of 
 temperature indicated by the Wedgwood pyrometer being 
 more than ten times greater than the range from the freezing 
 to the boiling point of water, has to be expressed within the 
 limits of only -Jths of an inch, this being the extent to which 
 a cylinder of clay contracts between a faint red heat at about 
 950° Fahr. and the melting point of cast iron at 2800° Fahr. 
 It is true this very small range of Iths of an inch, divided as 
 it is into 240 parts, is made appreciable by Wedgwood’s 
 
TEMPERATURE OF FURNACES. 
 
 65 
 
 contrivance of reading off on a base or ruler about 2 feet 
 long, but the delicacy of observing and manipulating with 
 such an instrument is too great to render it available for 
 practical purposes, besides which the cones or cylinders of 
 clay can never be procured sufficiently uniform in structure. 
 
 Daniell’s pyrometer is, perhaps, superior to any other that 
 has been tried. Its indications are caused by the expansion 
 or contraction of a bar of platinum connected with a lever 
 which acts as an index. The dial on which the index 
 revolves affords room for a greatly increased space to read 
 off the results, but this instrument for practical use is liable to 
 some of the objections against Wedgwood’s pyrometer. The 
 recent methods pointed out by Mr. Prinsey for determining 
 high temperatures by means of fusing the metals and their 
 alloys, is far too troublesome and complicated for practical 
 use. The beautiful experiment of obtaining the temperature 
 of a furnace by means of thermo-electric currents is also far 
 too delicate for ordinary use, and until some contrivance 
 more capable of being reduced to daily practice shall be 
 introduced into gas-making, we must be content to be guided 
 in a great measure by the colours presented by the interior 
 of the furnace. Constant observation will, indeed, greatly 
 improve the faculty of estimating high heats by the shades 
 of colour which they present, and at all events enable the 
 observer to compare and adjust the working of his furnaces. 
 The following table of high temperatures, expressed in the 
 colours commonly used, with their corresponding tempera- 
 tures reduced to Fahrenheit’s scale, has been principally 
 compiled from M. Becquerel’s “ Traiffi de Physique : ” — 
 
 Faint red 960° Fahr. 
 
 Dull red 1290 „ 
 
 Brilliant red (colour of red oxide of lead) 1470 „ 
 
 Cherry red • 1650 ,, 
 
 Bright cherry red 1830 „ 
 
 Dull orange 2010 „ 
 
 Bright orange 2190 „ 
 
 White heat 2370 „ 
 
 Bright white 2550 „ 
 
 Brilliant white 2730 „ 
 
 Melting point of cast iron 2786 „ 
 
 Greatest heat of iron blast furnace . . 3300 
 
66 
 
 EFFECTS OF VARIOUS TEMPERATURES. 
 
 There are, however, difficulties in appreciating the various 
 degrees of heat by colour ; for instance, when heated retorts 
 are exposed to the direct action of daylight, the colour or 
 temperature appears lower than it really is ; or when they 
 are enclosed in a dark locality, on the contrary, the tempera- 
 ture seems to be higher than reality. The means of judging 
 the various degrees of temperature by sight is only acquired 
 by continued practice. 
 
 The technical name applied to the temperature of retorts 
 is “heat ” or “ heats ; ” thus it is expressed “ a good heat,” “a 
 low heat,” or “the heats were down,” “the heats were up,” &c., 
 terms sufficiently significant to require no explanation. 
 
 EFFECTS OF VARIOUS TEMPERATURES IN CARBONISING. 
 
 Coal when submitted to a temperature approaching to 
 600° Fahr. — that is, a very dull red heat as seen in the dark, 
 a degree of heat which slowly chars paper, but does not 
 inflame it — its volatile matter is resolved into tar and oil, 
 and little or no gas is evolved. 
 
 Mr. Young, of Bathgate, turned the knowledge of this 
 simple fact to very great advantage, by decomposing Bog- 
 head cannel coal at that degree of temperature whereby 
 oil and tar only are obtained, which are afterwards purified, 
 and universally known as paraffin oil. When the operation 
 is properly conducted, the quantity of gas evolved is very 
 small, in some cases perhaps not exceeding 50 feet or 100 feet 
 per ton, the rest of the volatile constituents being condensed 
 into liquid. 
 
 In the carbonisation of coal, in proportion as the heat of 
 the retorts increases, so is the quantity of gas augmented, and 
 the tar diminished. The best temperature for iron retorts 
 compatible with their durability and good yield of gas, 
 ranges from 1650° to 1800° Fahr., being cherry -red and 
 bright cherry-red ; but with clay retorts, a temperature 
 between dull and bright orange, or 2100° Fahr., is the most 
 suitable, giving vastly superior results in the production of 
 gas than can ever be attained by the use of iron retorts. 
 
 Iron retorts, when worked at a low temperature, are of 
 
EFFECTS OF VARIOUS TEMPERATURES. 
 
 G7 
 
 very considerable durability ; in this state no deposit or 
 incrustation takes place in them ; but these supposed advan- 
 tages are often very dearly purchased. The attention of 
 the writer was once called by a gas manager to the great 
 durability of his iron retorts, which had been in use upwards 
 of fifteen months, had never required clearing of carbon- 
 aceous deposit, and were almost in as good condition as 
 when first fixed. This was all substantially correct; but 
 on referring to the accounts, the yield of gas was ascertained 
 not to have exceeded 6,500 feet per ton ; whereas by an 
 alteration of furnaces, so that the proper temperature for the 
 retorts could be attained, the yield was afterwards 9,200 feet 
 per ton. By the low temperature a large portion of the coal 
 was converted into tar, and this in the locality being nearly 
 valueless, the enormous loss can be readily understood. 
 
 As stated, the most advantageous degree of heat for car- 
 bonising coal is about 2100° Fahr. ; but when iron retorts 
 are heated above 1800°, they are speedily destroyed, or 
 “ burnt out/’ Clay retorts on this account have an immense 
 superiority; they can be heated to the proper temperature 
 without the risk of injury ; they are of extraordinary dura- 
 bility (their average duration in some works being four years); 
 the quantity of coal carbonised by them is considerably greater, 
 and labour less than when iron retorts are used. These 
 combined circumstances have caused clay retorts to entirely 
 supersede those of iron. 
 
 The time the coal remains in the retort is called the 
 charge ; thus, if subjected to four hours* distillation or 
 carbonisation, it is termed a four hours’ charge ; if for six 
 hours, a six hours’ charge. The word charge also applies to 
 the quantity, as when a retort is supplied with a certain 
 weight of coal, say 140 lbs. or 2 cwt., as the case may be ; they 
 are respectively called a charge of 140 lbs. or a charge of 2 cwt. 
 
 The nature of the coal must regulate the quantity and 
 duration of the charge. Some descriptions, as cannels, yield 
 the gas very rapidly ; so in Scotland, where this is very 
 generally used, it is found necessary to have small charges 
 of about 1| cwt. per retort, or less, which is drawn every three 
 hours. With Newcastle coal, which does not yield its gas 
 
08 
 
 FUEL USED IN HEATING FURNACES. 
 
 so readily, 2 \ cwt. are very common charges, which is 
 worked off sometimes in five hours, but more generally in 
 six hours. 
 
 The coals destined for carbonisation should always be in 
 a dry state ; and when by accident they are otherwise, if 
 possible they should be placed along the retort-house and 
 opposite the beds in use, some hours before required, in order 
 to dry them. In addition to the evils of wet coals already 
 enumerated, according to the opinion of Mr. Lewis Thompson 
 the steam is converted into hydrogen, thus impoverishing the 
 gas ; but however correct this may appear in theory, from 
 my own observation it does not occur ip practice, the 
 heat to which the steam is exposed being insufficient for its 
 decomposition. 
 
 FUEL USED IN HEATING FURNACES. 
 
 The fuel commonly used for heating the furnace is the coke 
 produced in the retorts after the gas is expelled ; the 
 quantity of course varying according to the quality of coal 
 and coke, the construction of the furnaces, and the magnitude 
 of the operation. When Newcastle coal is used, the carbon- 
 isation is seldom effected, except in very extensive establish- 
 ments, with less than 25 per cent., or one quarter of the coke 
 obtained ; that is to say, to carbonise a ton of coal, about 
 3j cwt. of coke will be required as fuel for the furnaces. 
 
 Coal is usually spoken of by weight, and coke by measure. 
 Newcastle coal generally yields about 1 chaldron of 36 
 bushels, or from 13 to 14 cwt. of coke for every ton of coals. 
 In well-conducted medium size works about one-fourth of the 
 coke made is used as fuel in the furnaces, the surplus three - 
 fourths remaining for sale, as more particularly described 
 in the section devoted to residual products. In small estab- 
 lishments this per-centage of fuel is exceeded ; and in very 
 large works the fuel employed is often not more than 18 per 
 cent, of the coke produced. 
 
 Some years ago Mr. Croll introduced the system of 
 charging the furnaces with the red-hot coke, as drawn from 
 
ON THE MODE OF WORKING RETORTS. 
 
 69 
 
 the retorts ; there appears to be considerable saving effected 
 by this, which has induced many engineers and companies to 
 adopt it. 
 
 When tar is not a marketable commodity it can be used as 
 fuel with advantage ; for this purpose the ash-pit and door 
 are bricked up, but leaving two orifices of about 2 \ inches 
 square, the one above the other ; the upper being on a level 
 with the line of top of door, the other about 8 inches below 
 this. The furnace being filled with breeze to the level of 
 the bottom of lower opening, a gutter of angle iron, or a 
 gutter in the brickwork itself, inclines in the upper orifice 
 to the interior of furnace, and through this flows a small 
 stream of tar of about -^th of an inch in diameter. When 
 first used, a few pieces of wood are lighted in the furnace, 
 and the stream of tar flowing in, ignites as a flame at the 
 upper opening, whilst a portion of the tar is deposited in 
 front of the lower opening in the form of coke ; so that 
 the air entering the orifices becomes highly heated by the 
 flame above, and the combustion of the coke below. Fur- 
 naces by this means are kept at an excellent degree of 
 temperature. One great difficulty with tar as fuel is that 
 it acts as a flux on the brickwork, but this is remedied by 
 constructing the furnace expressly for this purpose. 
 
 The combustion of tar as fuel is facilitated by allowing a 
 very small quantity of water to drop continuously and inter- 
 mix with it in the channel; this avoids the smoke which 
 would otherwise pass off by the chimney, and the water itself 
 becoming combustible aids as fuel. By adopting this system 
 no smoke arises, no coke is employed, and the economy in 
 some cases is remarkably important. A cwt. of tar is equal 
 to 1^ cwt. of coke, requiring about a quart of water to be 
 intermixed with it during combustion. 
 
 ON THE MODE OF WORKING RETORTS. 
 
 The magnitude of the works must always decide the mode 
 of operation. In large establishments, where double retorts 
 are used, being open at both ends, a double set of men is 
 
70 
 
 ON THE MODE OF WORKING RETORTS. 
 
 required to work them so as to be enabled to charge the two 
 ends simultaneously. The economy of this, over the old 
 method of setting the retorts back to back in different ovens, 
 is very considerable. 
 
 Where double retorts are used, each end is worked with 
 at least three stokers and an extra man for preparing the lids 
 of the mouth -pieces. Others are required for extinguishing 
 the coke, wheeling the coal into the retort-house, clinkering 
 furnaces, and attending to fires. Three stokers, assisted by 
 a man to extinguish the coke, will perform all the work of 
 taking off the lids, raking out the coke, extinguishing and 
 wheeling it away from a bench of seven retotts, in twelve or 
 thirteen minutes ; they will then put the proper charge for 
 each retort in the scoop, deliver its contents, and be ready 
 for charging another bench in a further space of seven 
 minutes, while a fourth workman will in the meantime 
 have put on the lids, so that the whole work of discharging 
 and charging the seven retorts will occupy barely twenty 
 minutes. 
 
 This extreme dexterity is of course only acquired by long 
 practice, and it must be admitted the labour is very severe ; 
 but this is moderated by the time the men have for repose 
 between the charges. The first process, in discharging or 
 drawing, is for one or two of the men to relieve the screws 
 of the mouth-pieces of the retorts about to be discharged, by 
 giving three or four rapid turns; another man instantly gives 
 a knock to each of the cross bars to disengage them from the 
 ears of the lid, and at the same time strikes the lid a blow w'ith 
 a piece of iron or hammer, in order to break the luting, and a 
 light is immediately applied to prevent explosion, which would 
 be likely to crack the retort if of clay. For want of this pre- 
 caution, many lamentable accidents have happened through 
 the gas exploding when combined with atmospheric air. 
 The men then lift oft the cross bar and screw of each retort, 
 placing them on the ground, and then each seizes hold of a 
 lid in both hands, lifting by the projecting ears, and placing 
 it aside to cool, ready for luting for another charge. 
 
 Three of the stokers then take up their iron rakes, which 
 are simply rods of f-inch iron, about 12 feet long, having a 
 
ON THE MODE OF WORKING RETORTS. 
 
 71 
 
 handle at one end; the other end being turned at right 
 angles is flat, about 6 inches long, 2 inches wide, and ^-inch 
 thick. These are inserted in the retort, and the red-hot coke 
 drawn to the mouth, whence it drops into the .coke vault, 
 where there is a man ready to extinguish by throwing water 
 on it ; or when there is no vault the coke drops into iron 
 barrows placed ready to receive it, and wheeled rapidly away 
 when the charge is withdrawn. If the coke were not imme- 
 diately extinguished it would smoulder, and the surface become 
 covered with earthy ash, which detracts from its appearance 
 and value. 
 
 Formerly, in charging retorts, the operation being compa- 
 ratively very protracted, there was a considerable loss of gas, 
 in addition to the time and extra fatigue to the men. In 
 order to remedy these inconveniences, a method has been 
 contrived for depositing the whole charge in the retort at 
 once ; for this purpose an iron scoop is used, this being a 
 semi-cylinder of sheet iron from 8 to 10 feet long and 10 or 
 12 inches diameter, with a cross handle at the end to assist 
 in lifting and turning it round to empty the coals in the 
 retort. 
 
 The charge of coal is placed in the scoop while it rests on 
 the ground, having a bent rod underneath for the purpose of 
 lifting it : one man takes hold of the cross handle, and two 
 others lift the other end by the bent rod and introduce it into 
 the mouth of the retort. The scoop with its contents is then 
 pushed forward to the further end, turned completely over, 
 and immediately withdrawn, leaving the coal in the retort, 
 which is raked into a layer of uniform thickness, when the 
 lid, previously luted and ready, is placed in its position and 
 screwed up as quickly as possible. The operation of charging 
 a retort with the scoop does not occupy more than thirty or 
 forty seconds, so that very little escape of gas can take place. 
 Hence the scoop has come generally into use wherever the 
 works are large enough to supply three men for the purpose 
 of working it. The composition for luting the retorts is made 
 generally of the spent lime from the purifiers, mixed with a 
 little fire-clay or loam, and well worked up with water like 
 mortar. In large works it is prepared outside the retort 
 
72 
 
 ON THE MODE OF WORKING RETORTS. 
 
 bouse and brought in by wheelbarrows as required. In 
 dressing the retort-lid with the luting, the workman uses a 
 trowel, and works a little of it up on a board, and applies it 
 all round the rim, taking care previously to clear off the old 
 lilting. 
 
 In small works, which do not permit of the necessary men 
 being employed to work double retorts, single retorts, gene- 
 rally about 8 feet long, are used. These are charged by 
 means of the shovel, and the process is necessarily more 
 tedious than the scoop, and the expenses of labour for car- 
 bonisation increased. 
 
 The beds or ovens of single retorts in very small works 
 are placed side by side, and extend the length of the retort- 
 house. In works of larger magnitude they are placed back 
 to back. 
 
 The number of men required to carbonise a given quan- 
 tity of coal depends on the size of the works. At extensive 
 establishments each man carbonises from five to six tons of 
 coal per day, whilst in small works, where iron retorts are 
 used, often 25 cwt. is not attained. In Scotland formerly, 
 and perhaps at present, it was sometimes the custom for the 
 stokers to be engaged by piece-work. 
 
 A very essential point in the carbonisation of coal is to 
 keep the interior of the retorts free from incrustation, and, 
 indeed, as far as possible, to prevent it taking place. This 
 incrustation, as already referred to, is a solidification of the 
 richest parts (the heavy hydro-carbons) of the gas, and when 
 gas is subjected to a high pressure and great heat, these are 
 deposited in great abundance. 
 
 It also entails several other disadvantages, — it increases the 
 fuel and labour : by its obstruction renders more retorts 
 necessary, so increasing the capital invested ; and wherever it 
 abounds the coke is always of inferior quality. In iron 
 retorts, where the heats are not so high as in those of clay, 
 supposing both to be subject to the same pressure, this deposit 
 does not take place so speedily ; but it is always in excess 
 in the hottest part of the retort, which is generally the closed 
 end, and diminishes towards the mouth in proportion to the 
 diminished temperature. It has often been considered that 
 
COAL USED IN MAKING GAS. 
 
 73 
 
 the exhauster was unnecessary wherever iron retorts were 
 used ; but wherever the incrustation of carbon occurs, either 
 in iron or clay retorts, it may be taken as a direct proof of 
 the necessity of that instrument. 
 
 When clay retorts are at the most advantageous tempera- 
 ture, and the gas in them is under a pressure of 18 or 21 
 inches (which is not uncommon when no exhauster is used), 
 two or three weeks are sufficient for a very inconvenient accu- 
 mulation of carbon in the retorts : but when the pressure is 
 diminished by the exhauster to about 1 inch, the same quan- 
 tity of accumulation would require from three to four months. 
 
 The mode sometimes adopted to clear out this carbon (the 
 furnace being heated as usual), is to project from a tube a 
 small jet of steam on to the crust attached to the roof of the 
 retort. The oxygen of the steam combines with the carbon 
 which gradually diminishes, and when sufficiently thin can 
 be easily detached by means of a chisel bar, it being removed 
 from the roof, like an arch without the key ; the deposit of the 
 sides breaks away in large lumps. 
 
 Others prefer a periodical cleansing by leaving the retorts 
 exposed to the action of the atmosphere, the heats being kept 
 up as usual ; for this purpose the door is placed in its position, 
 leaving about an inch space between it and the mouth-piece. 
 The air enters and gradually cleanses the retort. It is always 
 advisable to clear out this deposit before it becomes too thick; 
 if neglected, its accumulation is very rapid. 
 
 In all coal, combined with the ash, there are particles of 
 iron, lime, and other substances, which fuse and become slag, 
 or clinker, which deposits itself between the furnace bars and 
 stops the current of air. To effectually remove this the bars 
 should be loose, as hereafter stated ; and the clinker is readily 
 detached by means of a suitable bar. 
 
 When the ascension pipes are placed too close to the fur- 
 naces, or when the wall of the furnace is not sufficiently thick, 
 the pipes are heated to such a degree that the tar in its pas- 
 sage is deposited thereon, as pitch, thereby causing a speedy 
 obstruction. 
 
74 
 
 CHOICE OF SITE FOR GAS-WORKS. 
 
 CHAPTER V. 
 
 SITE MOST APPROPRIATE FOR GAS-WORKS. — CONSIDERATIONS 
 
 IN CHOOSING SITE. OBSERVATIONS ON THE LOWEST 
 
 LEVELS FOR SITES. LEAKAGE OF MAINS. OBSERVATIONS 
 
 ON PLAN OF WORKS. — ESTIMATE OF CAPITAL OF WORKS. 
 
 CHOICE OF SITE FOR GAS-WORKS. 
 
 In the largest class of towns or cities, the site generally 
 chosen for gas-works has been the side of a canal or river, 
 so as to profit by the convenience of water carriage for the 
 supply of coal, purifying materials, pipes, bricks, retorts, 
 and apparatus, also for the economical transport of the 
 residues, as coke, tar, ammoniacal liquor, breeze, waste 
 lime, &c. 
 
 Since the establishment of railways, a site contiguous to a 
 line is found, so far as economy of transport is concerned, 
 equally advantageous ; whilst it is superior on some accounts, 
 not being, like the canal and river, liable to the contingencies 
 of frost. There is the further advantage in the railway, that 
 the coal is delivered daily and direct into the retort-house 
 ready for use, so avoiding the expenses of unloading the 
 barges, loading the trucks, and wheeling. 
 
 The Great Central Company’s Works, at Bow, afford an 
 excellent instance of this arrangement. A branch line is laid 
 down connecting the works with the railway which serves 
 for the supply of coal, and the rails are laid actually into the 
 retort-house, the rails being raised a sufficient height above 
 the level of the charging floor to enable the waggons to 
 tilt with perfect ease, and deposit the coal beneath, directly 
 opposite the furnaces where required. Nothing can surpass 
 this arrangement for economy and convenience. The most 
 eligible situation for erecting gas-works close to a railway 
 station is where the railway is on an embankment 12 
 or 14 feet high. A siding should here be constructed, 
 on which the coal-waggons turn out of the main line and 
 discharge their contents through shoots or other well-known 
 contrivances. The retort-house should be erected as close 
 
CHOICE OF SITE FOE GAS-WORKS. 
 
 75 
 
 to the siding as convenient, so that the coal as delivered from 
 the waggons will be quite ready for charging the retorts, 
 and all expense both of carting and -wheeling the coal will 
 be avoided. In the north of England this juxtaposition of 
 gas-works and railways is by no means uncommon, and 
 many small towns are reaping the advantage of lighting by 
 gas which might otherwise have long been without so great 
 an acquisition. 
 
 In some establishments which adjoin a canal or river, the 
 coal is delivered from the barge into iron waggons contain- 
 ing about a ton each ; these are raised by hoists, and 
 deposited on a line of rail, by which they are conveyed, 
 either into the retort-house for immediate use, or to be 
 stored. 
 
 There are few things connected with gas-lighting which 
 demand greater care than the choice of site for the intended 
 works. In making the selection due consideration must be 
 given to the probable objections that might be raised 
 on sanitary grounds, and if there is an improving or superior 
 part of the town, this should be avoided. Two London 
 companies, whose w T orks are situated in improving and 
 superior neighbourhoods, were for some years put to great 
 expense, in consequence of the complaints of evils that w T ere 
 said to occur to the neighbourhood from the proximity of 
 their works. 
 
 For convenience of communication, and economy in the 
 cost of mains, it is essential that the works should not be too 
 distant from the locality to be supplied. There are other 
 circumstances depending on the relative value of property, 
 the means of acquiring it, the nature of the ground, whether 
 suitable for the economical construction of the edifices, or if 
 liable to be submerged by heavy floods. These are points 
 which demand serious attention. 
 
 It has frequently been laid down as an imperative law, 
 that gas-works should always be established at the very 
 lowest level of the district to be supplied, and often in follow* 
 ing this impression, an unsuitable site has been chosen, the 
 land has been procured at a fabulous price, and perhaps 
 afterwards the works, from their position, have been the 
 
 E 2 
 
76 
 
 CHOICE OF SITE FOR GAS-WORKS. 
 
 source of continued complaints ; whereas by the exercise of 
 proper judgment a more advantageous and suitable site 
 might have been procured at considerably less cost. 
 
 The motive assigned for the necessity of so placing gas- 
 works, is that the lower districts are by these means better 
 supplied ; and there might be some reason in this, if gas 
 derived its force or pressure from its own ascensive power, 
 but this is not the case, as the pressure is dependent on the 
 holder which expels the gas. Too much importance has 
 generally been attached to this law, and I will give a case in 
 order to prove how one might err in following it. 
 
 Gas by its lightness has an ascensive power ; and when 
 enclosed in the mains, at the period that there is no draught 
 or supply therefrom, the ascensive power is equal to about 
 1 inch pressure for every 100 feet rise of elevation. So in a 
 town where the difference between the highest and lowest 
 level is 200 feet, the pressure in the lowest level being -f^ths 
 of an inch, that in the highest parts would be ffths. The 
 loss of gas by leakage from the mains is always in direct 
 proportion to the square root of the pressure of the gas, so 
 if from a certain main the loss be 500 feet per hour, the gas 
 being at ffths pressure, it would be 400 feet at io^ths, and 
 only 800 feet per hour with a pressure of i%ths. Therefore, 
 in choosing a site, it becomes a serious consideration to avoid 
 as much as possible the high pressure, which existing during 
 the whole of the day, when there is no lighting, would 
 entail a great loss. 
 
 Now if in the town already referred to, the works were to 
 be constructed midway between the two levels, with two 
 distinct mains to supply the upper and lower districts, then 
 a maximum pressure of -bjths would be sufficient ; and if the 
 general lighting were in the upper part of the town, all 
 other circumstances being equally favourable, great advantage 
 would be gained by placing the works midway. As a rule, 
 it is generally better to place the works in the lower part of 
 the district, but the difference of a few feet in the level will 
 never be of material consequence. 
 
 When there is the full supply from the mains, the pressure 
 is not always in relation to the level ; but being according to 
 
PLAN OF WORKS. 
 
 77 
 
 the size of the mains, the highest part of a town, that might 
 have extraordinary pressure when there is little draught, as 
 during the day, might through the insufficiency of the 
 mains, or through an obstruction of naphthaline or water, be 
 almost in darkness at night. 
 
 PLAN OF WORKS. 
 
 Previously to the arrangement of the plan of works, the 
 nature of the ground chosen for the site should be ascer- 
 tained. This is readily done by sinking a well to the 
 desired depth of the foundations of intended gas-holders. 
 A guide is then obtained as to the mode of constructing and 
 the cost. Should water be abundant within a short distance 
 of the surface, then cast-iron tanks for the gas-holders must be 
 decided on. Should the substratum be of clay, ordinary earth, 
 or gravel ; a brick or stone tank for the gas-holder can be 
 constructed with facility and economy. Should it be “ made 
 ground,” that is ground which had formerly been transported 
 from elsewhere, then extraordinary precautions in the founda- 
 tions are necessary ; and should rock be encountered the 
 question then arises whether it would be more advantageous 
 to excavate and construct the tank in masonry, or avoid the 
 excavation by erecting an iron tank. 
 
 The price of building materials and their nature must also 
 influence the arrangement of a plan of works. In some parts 
 bricks and puddle are abundant and cheap ; in other places 
 neither are to be had, unless at an enormous cost for trans- 
 port, which renders their employment entirely out of the 
 question. 
 
 In designing a new works there are a few rules to follow. 
 To construct in such a manner, that at a future period, 
 when required, the works may be increased without much 
 demolition. The retort-house may be so arranged as to be 
 doubled hereafter ; the ground so disposed as to admit 
 of extra gas-holders, and sufficient space left for increase of 
 purifiers. The entrance of the works ought to be placed, 
 when practicable, at that part of the site nearest the locality 
 to be supplied. 
 
78 
 
 PLAN OF WORKS. 
 
 i 
 
 i 
 
 o 
 
 lb 
 
 PLAN 
 
80 
 
 PLAJST OF WORKS. 
 
 In the disposition of the various buildings, the manager’s 
 or foreman’s dwelling should be at the entrance, so that all 
 may be under the immediate notice of the residing respon- 
 sible person. The offices, store-rooms, and weighbridge — 
 for the purpose of weighing the coal as it enters, and the 
 coke, when sold by weight, as it leaves — should immediately 
 adjoin the dwelling. A plurality of entrances to a works 
 ought to be avoided. 
 
 In order to avoid the expense of unnecessary transport 
 the coal-stores, coke spreading floor, and shed for coke, 
 should adjoin the retort-house. Sometimes a part of the 
 coal-store is paved with bricks on edge serving for spreading- 
 floor, and for extinguishing the coke. 
 
 The purifying house, tar tank, lime, and purifying mate- 
 rial store, are generally separated from the rest of the works, 
 and placed where they may be considered the least offensive. 
 When there is plenty of room the gas-holders are separated 
 from the other buildings ; but provision should always be 
 made for future extensions. 
 
 Old works, which have been altered frequently from time 
 to time, to suit the demands on them, do not afford the same 
 facilities for excellence of design as those of more modern 
 construction. One of the most perfect plans of gas-works of 
 magnitude, is that of the Liverpool United Gas Company at 
 Wavertree ; it is a combination of every advantage, alike for 
 the company and their men, and reflects the highest credit 
 on the engineer, Mr. King. The plan of the new works of 
 the London Gas Company, as also that of the Great Central 
 Company, are both very excellent and worthy of imitation. 
 
 The accompanying figure (Fig. 2) represents the ground 
 plan of a small works designed and erected by Mr. Penny, 
 of London, for St. Mary Cray, Kent. Fig. 3 is an elevation 
 of the same. It is a favourable specimen of modern works, 
 and appears to be laid out with care and judgment. These 
 works, in their present form, are capable of manufacturing 
 and supplying about 60,000 cubic feet per diem ; with another 
 gas-holder, and an increase in some of the apparatus, double 
 that quantity could be produced. The cost of these, but not 
 including the main pipes, was about £3,200. 
 
PLAN OF WORKS. 
 
 81 
 
 The magnitude of gas-works and plant is generally esti- 
 mated by their annual production ; thus a works is described 
 as ‘‘ten million,” signifying that number of feet per annum, 
 the maximum production in the depth of winter being about 
 44,000 feet, the minimum, at midsummer, being about 18,000 
 feet per day. In a works of 50 million per annum, the maximum 
 production is about 220,000 feet per day, and the minimum 
 90,000, and so on in proportion for the larger establishments. 
 
 But there are works of such extraordinary magnitude that 
 the production is estimated by the maximum per diem. The 
 maximum produce of each of the Imperial Company’s works 
 is about 5,000,000 feet, making with their three stations a 
 daily production, in the depth of winter, of about 15,000,000 
 cubic feet of gas. 
 
 The capital required for gas-works is variable : for modern 
 works from <£600 to £800 per million feet per annum is 
 about sufficient ; or if the capital be estimated according to 
 the population, from 15s. to 25s. per head may be calculated. 
 The capital of old-established works usually surpasses these 
 estimates, and in some instances the excess is very material, 
 arising from the high price formerly paid for the mains, appa- 
 ratus, and the necessary contingencies attending the first 
 establishment of gas-works. The general improvement in the 
 modern construction of the various apparatus, contributes also 
 to the diminished price. 
 
 When gas-lighting is properly developed, which mainly 
 depends on the company supplying according to the quality 
 and price of the gas, and the facilities afforded for its adop- 
 tion, the average consumption per head is from 2,000 to 
 2,500 feet per annum. Whenever the consumption of a town 
 is proportionably small, as a rule, it arises from mismanage- 
 ment on the part of the company. 
 
82 
 
 ON THE RETORT-IIOUSE AND BUILDINGS. 
 
 CHAPTER VI. 
 
 ON THE RETORT-HOUSE AND BUILDINGS. 
 
 The Retort-house, as its name implies, contains the ovens, 
 or, as more generally termed, “ settings” or “ benches ” of 
 retorts, in which the operation of distillation or carbonisation 
 of coal is conducted. With very few exceptions this is a rec- 
 tangular building, covered usually with iron principals, and 
 slates or tiles. When economy is a consideration, the roof 
 is of sheet iron, the durability of which is, however, very 
 limited. The width of this edifice in large establishments is 
 from 52 to 70 feet, and from 30 to 32 feet high ; the length, 
 of course, depending on the size of works. 
 
 A few of the largest establishments have the retort-house 
 very differently arranged to those of the great majority. In 
 the centre, and extending from end to end, are a series of 
 arches built on suitable piers. On these are constructed the 
 ovens or benches, the piers of which correspond with those 
 below. On a level with the furnaces of the retorts there is a 
 stage or firing floor, where the stokers work when charging 
 or drawing the retorts. This is about 8 feet from the ground, 
 and is commonly formed by cast-iron columns and plates, and 
 extends on each side throughout the length of the retort- 
 house, leaving a space of about 2 feet wide immediately in 
 front of the furnaces, through which the coke drops when 
 drawn from the retort, into the space below, which is called 
 the coke -hole, or coke -vault. 
 
 The coke -vault possesses some advantages, for where it 
 exists the stokers are not exposed to the continuous heat of 
 the coke when drawn ; since it falls immediately below, where 
 it is extinguished by other men. The furnaces are also clin- 
 kered from below, which saves the trouble of raking out the 
 fire, thus avoiding the cooling effect of a current of air passing 
 through the oven, an evil which always happens where the 
 furnaces are clinkered from the door ; and the convenience 
 of loading the coke direct into the carts from the coke-vault 
 is also a recommendation. The objections to the coke -vault 
 are the expense in construction ; the coke in falling breaks, 
 
ON THE RETORT-HOUSE AND BUILDINGS. 
 
 83 
 
 and it is further injured on account of the very limited space 
 for spreading, extinguishing, and storage. 
 
 There are few works which have coke -vaults attached to 
 the retort-house. Generally the ovens are built on suitable 
 foundations, ensuring solidity to the structure, and preventing 
 as much as possible radiation of heat from beneath. In these 
 the furnaces are nearly on a level with the ground, and the 
 coke when drawn falls into iron barrows, and is wheeled away 
 to a separate place for the purpose of extinguishing. 
 
 In retort-houses having no coke -vault, the tops of the ash 
 or evaporating pans are a few inches below the level of the 
 ground, which is usually paved with fire-bricks on edge. 
 Sometimes cast-iron plates have been tried as a substitute for 
 brick paving, but the metal conducts the heat to the feet of 
 the men with such facility as to render it objectionable. 
 
 The benches of the retorts were formerly placed back to 
 back, so that a building containing say sixty single benches, 
 each about 8 feet 6 inches long, thirty of these had their open 
 ends or mouthpieces towards one side of the retort-house, the 
 other thirty having their mouthpieces towards the other side, 
 and a 9 -inch or 14-inch wall separated the benches. These 
 are called single settings. Of late years this method has been 
 superseded by dispensing with the partition wall, and so the 
 two single beds form one continuous oven, each retort being 
 about 18 or 20 feet long, open throughout, and having a 
 mouthpiece at each end. These are called double beds or 
 double retorts, and the economy derived from this plan is 
 very considerable, but they can only be employed in large 
 establishments, where there are at least six stokers to charge 
 both ends of the retorts simultaneously. 
 
 In small works the retort-house is constructed only for a 
 single row of ovens, which are placed side by side, often 
 extending the entire length of the building. In this case 
 the retort-house is from 24 to 28 feet wide, and from 15 to 
 18 feet high. The beds are placed at one side, leaving a space 
 of from 13 to 16 feet wide for charging and drawing, also as 
 a deposit of coal for immediate use. In works of the smallest 
 descriptions the retort-house and coal-store frequently form 
 one and the same building; this, however, is objectionable. 
 
84 
 
 ON THE RETORT-HOUSE AND BUILDINGS. 
 
 In deciding on the dimensions of the retort-house, every 
 consideration must be made, not only of the present require- 
 ments of the locality to be supplied, but also that of the 
 future ; for gas, even at the present day, is very far from 
 attaining its full development, and it is impossible to antici- 
 pate the various future uses to which it jnay be applied ; but 
 the experience of the past demonstrates the necessity of 
 making every reasonable provision for extension. It is also 
 important to have a good margin, and not to estimate the 
 power of carbonisation too highly ; for by unforeseen circum- 
 stances, the supply of the ordinary coal may be temporarily 
 discontinued, when resource must be had to that of inferior 
 quality, which yields less gas and in consequence requires 
 more retorts. 
 
 No definite rule can be laid down for the dimensions of 
 the retort-house ; this must entirely depend on the mode of 
 setting. With one kind of setting considerably more coal is 
 carbonised than with another ; it depends whether they are 
 single or double, whether the retorts are of clay or iron, the 
 kind of coal employed, and other circumstances. 
 
 Mr. Clegg gives for the thickness of the walls in retort- 
 houses built by him, 18 inches from the ground-line to the 
 firing-floor, and 14 inches from the firing-floor to the top : 
 he states, however, that where funds are available, he would 
 prefer increasing each of these dimensions by half a brick, at 
 all events to the height of the coal-store, which reaches to 
 within 6 feet of the wall plate or top of the walls of the 
 retort-house. 
 
 There is nothing peculiar in the construction of the walls 
 of the retort-house, more than other buildings of the 
 same height ; of course precautions should be taken to secure 
 a good foundation, to extend the base by footings, and where 
 necessary to use pileing or concrete according to the nature 
 of the foundation. On these points no general directions 
 can be given, as the treatment must vary with the special 
 circumstances of the case ; the general rule, however, 
 applicable to ordinary foundations will apply here. 
 
 The cost of erecting retort-houses will of course vary with 
 the price of labour and building materials in the district. 
 
ON THE RETORT-HOUSE AND BUILDINGS. 
 
 85 
 
 Brickwork varies, in different parts of England, from ,£9 to 
 £15 per rod, therefore it is useless to give the prices of any 
 particular district as a standard ; but the following examples 
 may be taken as an average : — 
 
 A retort-house 32 ft. long, 25 ft. wide, and 16 ft. high, 
 with iron roof, the firing -floor paved with bricks on edge, 
 and square chimney 30 ft. high, cost £280. 
 
 In Mr. Clegg’s “ Treatise on Coal Gas,” it is stated, a 
 retort-liouse 50 ft. long, 24 ft. wide, and 18 ft. high, the roof 
 of wrought iron and common tiles, and with a chimney 70 ft. 
 above the ground, is estimated at £550. 
 
 The next example given, is a retort-house and a coke- 
 shed built on one side of it, on lower ground, so that the 
 ground-line on one side was the firing-floor for the retorts, 
 and the falling nature of the ground gave facilities for the 
 coke to slide down the inclined plane into the shed. 
 
 This building, which was 70 feet long, including a chimney- 
 
 90 feet high, but exclusive of foundations, cost . . £1200 
 
 Wrought-iron roof, slated J 90 
 
 Ventilator of wood, slated 43 
 
 £1433 
 
 Mr. Clegg’s next example is on a much larger scale, 
 namely, a retort-house 200 ft. long and 54 ft. wide, with 
 coke-vaults on the ground floor. His estimate for this build- 
 ing is as follows : — 
 
 Brickwork in outside walls, iron girders, flagged firing- 
 
 floor, and centre portion for supporting retort benches £3950 
 
 Wrought-iron roof, slated 700 
 
 Chimney, 120 feet high 180 
 
 £4830 
 
 Mr. Barlow gives the size of a retort-house of 640 ft. iu 
 length by 52 ft. in breadth and 24 ft. high. 
 
 He estimates the building, including an iron roof 
 
 covered with slates, at £16,640 
 
 Coal-sheds, to contain 10,000 tons of coal .... 9,000 
 
 Chimney, 120 feet high, with flues lined with fire-brick 450 
 800 retorts, namely, 400 clay and 400 iron, set complete, 
 with hydraulic main, mouth-pieces, ascension-pipes, 
 dip and bridge pipes, complete, at £17 15,?. each . 14,200 
 
 £40.290 
 
86 
 
 ON THE RETORT-HOUSE AND BUILDINGS. 
 
 The following is Mr. Croll’s estimate for a retort-house 
 capable of containing 504 retorts, including the chimney, the 
 purifying-house, the coal-stores, and a boundary wall to sur- 
 round the works. 
 
 £ s . d. 
 
 436 rods 33 feet standard brickwork, at £11 per 
 
 rod 4797 10 0 
 
 793| yards of concrete, at 6$ 237 14 0 
 
 Roofing, as per tender 6615 0 0 
 
 Iron floor for purifying-house, 26 tons, at £10 per ton 260 0 0 
 
 12 tons of beams to support flooring, at £10 . . 120 0 0 
 
 504 retorts, as per former estimate, less £899 13s. 4^. 
 
 for brick-work and concrete included in the above 6576 9 0 
 
 £18,606 13 0 
 
 Particular precaution is necessary in the erection of ovens, 
 either in small or large works ; so that sufficient space be 
 left for the expansion of the masonry, if not, there is every 
 probability of the walls being forced out by the expansion or 
 elongation of the brickwork. This precaution is particularly 
 requisite for chimney-stacks, which should always be de- 
 tached, and any flue into them should enter like a tube, with 
 a slight space around it ; by this means, when the brick- 
 work expands, the flue will not press against the chimney. 
 Through want of attention on this point, many excellent 
 stacks have been thrown so far off the perpendicular as to 
 require rebuilding. 
 
 In modern large retort-houses, they are built in blocks of 
 about 100 ft. long, having free communication with each 
 other ; there is often a ventilating shaft, constructed of 
 wrought iron, with a valve or door, so by this the heated 
 atmosphere of the building is considerably moderated, contri- 
 buting much to the comfort of the men. And to the honour 
 of many engineers, it must be said, that the comforts of the 
 men employed in their respective companies have had their 
 greatest consideration. In some gas-works libraries are 
 established, in others baths and mutual benefit societies ; and 
 there are gas-works that can boast of having a musical band, 
 composed of the stokers and men of the establishment — cir- 
 cumstances alike praiseworthy to the employers and employed. 
 
THE COAL-STORE. 
 
 87 
 
 THE COAL-STORE. 
 
 This is generally attached to the retort-house, with every 
 facility of communication for the purpose of transporting the 
 coals. The dimensions of this building must be defined by 
 circumstances. If the railway is the means of transport, 
 then small stores may be sufficient, but should the ordinary 
 means of obtaining the supply of coal be by river or canal, 
 in order to provide against the probability of frost — the store 
 should be ample for a supply of at least two months ; and 
 whenever there are increased difficulties in obtaining the 
 supply, it should be augmented in proportion. It is always 
 advisable to have the coal-store sufficiently large, so that in 
 summer, when not required for coal (and coke is abundant), 
 it can be converted into a store for that residue. When 
 employed as a spreading-floor, it should by all means be 
 paved with fire-bricks, as stone is liable to crack with the 
 heat. When not used for that object, ordinary common 
 paving will answer the purpose. 
 
 PURIFYING-HOUSE. 
 
 The purifying house has, where practicable, the sides 
 open, to permit a good current of air to pass through, 
 and carry off any noxious gases. There should also be a 
 ventilator in the roof, so that in the event of the lutes 
 “ blowing,” the gas may escape readily at the top. The 
 roof of the purifying -house is usually of wooden principals 
 and tiles. Iron would be very speedily destroyed by the 
 action of the sulphur emanating from the waste purifying 
 material. In some works the purifiers are uncovered, this 
 has the inconvenience of unnecessarily exposing the men at 
 times to the inclemency of the weather, and ought to be 
 avoided by a suitable roofing. 
 
 ENGINE, BOILER, AND EXHAUSTER HOUSE. 
 
 In the most moderate sized gas-works at the present day 
 the steam-engine is an important auxiliary ; formerly the 
 only use for an engine in a works was for pumping water, or 
 for keeping in motion the wet lime purifiers, and in many 
 
88 
 
 STATION METER-HOUSE. 
 
 works of considerable capacity, where neither of these were 
 requisite, a steam-engine did not exist. 
 
 The use of clay retorts has caused motive power for work- 
 ing the exhauster, to be introduced into gas-works of all 
 denominations. 
 
 The engine, boilers, and exhauster being attended by the 
 same man, are usually in the same building, and more care is 
 usually displayed in this than any other part of a gas-works. 
 The edifice is often constructed with taste, and is no doubt 
 an inducement to the men who have charge of the machinery 
 to keep it cleanly, and in order with the building itself. 
 
 STATION METER AND GOVERNOR HOUSE. 
 
 These, like the engine-house, should only be accessible to 
 the foreman, &c., and the man in charge. 
 
 When there are several gas-holders together, it is not 
 uncommon for the station-meter to be placed close to them, 
 and the valves of the various gas-holders placed in the meter- 
 house. Or on other occasions there is a distinct house for the 
 valves ; but more commonly valves are attached to their 
 respective holders. The most compact manner is the 
 former, either when collected in the meter-house or a distinct 
 valve-house. It is true there is some expense attached to 
 this system, but it is much more convenient and secure. 
 
 The governor is frequently placed in the same building as 
 the station meter, but more generally a detached building is 
 constructed expressly for it ; in large works there are several 
 lines of mains issuing from the works, each of w'hich has its 
 corresponding governor, with the various pressure gauges 
 and pressure registers. 
 
 CHIMNEY OR STACK. 
 
 The chimney of a gas-w T orks, resembling all others, serves 
 to separate the issuing hot air of the fire from the atmo- 
 sphere around. 
 
 Air when heated, becoming considerably lighter, has an 
 ascensive power dependent on the degree of temperature it 
 possesses ; and when highly heated — as when passing from 
 
CHIMNEY OR STACK. 
 
 89 
 
 the furnaces — is capable of ascending with great force and 
 rapidity. The column of heated air thus ascending exerts 
 itself, and draws through the furnace bars a quantity of cold 
 air, which intermixes with the fuel, and produces combus- 
 tion. The cold air is heated, and ascends, producing what 
 is generally termed draught or current. The force of this 
 draught or current is equal to the difference between the 
 weight of the column of air in the shaft, and the weight of a 
 like column of air of the atmosphere outside the stack. 
 
 High stacks are constructed principally for the purpose of 
 carrying off smoke or offensive products to a great height, 
 where they are diffused over a large space, and a nuisance 
 which otherwise would exist is prevented. In some chemical 
 manufactories, the stacks are made of great dimensions, — one 
 near Glasgow is 100 feet high. By means of this all noxious 
 gases that may be generated are carried to and issue from 
 the top, without the least prejudice to the neighbourhood. 
 
 The largest chimney for a gas-works is that of the Edin- 
 burgh Company, and is a fine piece of building, being 329 feet 
 above the level of the ground, perfectly plomb, and without 
 the slightest crack or fissure throughout the height. The 
 current therein, when in ordinary working order, is equal 
 to an exhaust of 2^ inches of water — a strong current in 
 an ordinary chimney seldom exceeding half an inch exhaust. 
 The cost of this stack, with the lateral flues, was upwards 
 of £4,000. 
 
 Some engineers attach little importance to high shafts ; and 
 in neighbourhoods where the issuing smoke is not preju- 
 dicial, small chimneys are employed. At the Great Central 
 Company’s works, instead of a main stack for the furnaces, 
 there are a series of small chimneys, each of an internal area 
 of about 3 feet, and sufficient for six benches of retorts. 
 They are built on the benches, each being about 20 feet high, 
 and placed at intermediate distances throughout the length 
 of the retort-house, and give every satisfaction. An advan- 
 tage with them is, that in the event of an insufficiency of 
 draught, a new chimney is erected in a few days, so supplying 
 the deficiency. This plan is also adopted at other large 
 establishments. 
 
90 
 
 CHIMNEY OR STACK. 
 
 Chimney stacks for gas-works are constructed in various 
 manners, the simplest and cheapest being the square form ; 
 but these are unsightly, and, offering greater resistance to 
 the wind, require to be built strong accordingly. Some stacks 
 are made circular, and others octagonal; the latter, when 
 surmounted on a square pedestal, with a neat capital on the 
 summit, have a remarkably good appearance, and the cost 
 does not exceed that of the circular form. 
 
 The ordinary chimneys of gas-works vary in height from 
 35 feet to 150 feet above the level of the ground ; their cost 
 for a given height depends mainly on their internal area and 
 the nature of the foundation. The ground being favourable, 
 the price of a square chimney, 35 ft. high, with an internal 
 area of 4 ft., will not exceed ,£30. An octagonal or circular 
 stack of 8 ft. internal area, and 60 ft. high, under the same 
 conditions as the former, will cost about £85. A similar stack 
 of 10 ft. area, and 100 ft. high, would be £180 to £200. 
 
 Chimney stacks, unless when placed in 'the centre of the 
 beds, should never be built in the retort-house, as they 
 occupy the space unnecessarily. Wherever constructed, they 
 should always be detached, and, on account of their great 
 weight and height, extraordinary precautions are necessary 
 in their foundations. The area of these must be determined 
 according to the degree of solidity of the ground where 
 erected; the softer the soil, of course the greater will be the 
 footings required. The pedestal for the base is usually one- 
 tenth of the height square. 
 
 Stacks for gas-works are always lined with fire-brick either 
 for a portion or the whole of the height. Sometimes the lining 
 is detached from the chimney, leaving a space for a current 
 of air to pass between the former and the latter, which pre- 
 vents the stack cracking. Small chimneys are usually con- 
 structed entirely of fire-bricks. 
 
 A mistaken notion often prevails, that by materially con- 
 tracting the stack at the top, the draught is increased ; 
 this, however, can only occur when of too great capacity. 
 The stack, although tapering on the exterior, is internally 
 nearly of one uniform area throughout, there being offsets 
 at certain distances, according to the height and form. In 
 
ON THE RETORTS USED IN GAS MAKING. 
 
 91 
 
 erecting, every eight or ten courses should be built with hoop 
 iron ; when this is not done, the stack frequently cracks, 
 afterwards demanding the use of hooping on the exterior, 
 which is unsightly. 
 
 CHAPTER VII. 
 
 ON THE RETORTS USED IN GAS MAKING. 
 
 The earthenware or iron vessels in which coal is distilled for 
 the purpose of separating the gas from the solid carbon are 
 called retorts — a name borrowed from the language of che- 
 mistry, in which a retort signifies a vessel either of glass, 
 earthenware, or metal, in which distillation or decomposition 
 is effected by the application of heat. The French, in their 
 word cornue , have obviously adopted the name of a chemical 
 vessel in the same manner to designate the retorts used in 
 the distillation of coal gas. 
 
 The earliest experiments on the form of retorts appear to 
 have been made by Mr. Murdoch, when he erected the gas 
 apparatus at the works of Messrs. Boulton and Watt, at Soho. 
 The retort used there was a circular tube, the diameter ot 
 which was equal to a third of its length. This was placed 
 vertically over the fire-grate, and a horizontal pipe from the 
 upper end conveyed away the gas, the open end of the vessel 
 being of course uppermost. The form of these vertical retorts 
 was afterwards varied, as it was found very inconvenient to 
 extract the coke from them, when opened only at the top. 
 The next form of retort was somewhat in the shape of a wine 
 decanter; that is, of larger diameter at the base than at the 
 top. The fire acted on the bottom and sides of this. In the 
 side, close to the bottom, was an opening for extracting 
 the coke, and a vertical pipe went off near the top for carry- 
 ing away the gas. This form did not answer, owing to the 
 mass of coal lying too much in a heap, and not presenting 
 sufficient surface, so that an outer coat of coke was formed, 
 which prevented the heat from penetrating quickly to the 
 interior. 
 
92 
 
 ON THE RETORTS USED IN GAS MAKING. 
 
 The next contrivance was that of a cylindrical retort placed 
 diagonally in the furnace. From this the coke could be 
 readily extracted at the lower end, but the heat did not act 
 so effectually as in the next form, which was that of a cylin- 
 drical retort placed horizontally. The shape of this last was 
 varied, being sometimes cylindrical in section, sometimes oval 
 or ear-shaped, but the horizontal position and mode of setting 
 were retained. 
 
 During a series of years various systems were adopted 
 before an economical mode of retort-oven or setting could be 
 obtained. At first, retorts were set in sjngle ovens, each being 
 heated by a distinct furnace ; afterwards, five were heated by 
 three furnaces ; subsequently, one fire was sufficient for five 
 retorts ; and such is the progress made in this, that at the 
 present day very commonly a setting of nine or ten large 
 clay retorts is heated by a single furnace. 
 
 Amongst the various attempts to improve the settings of 
 retorts may be mentioned that of Mr. Brunton, the web retort 
 of Mr. Clegg, and the reciprocating retort of Mr. Lowe. 
 
 The novelty in Mr. Brunton’s plan w T as the employment of 
 a short retort, diminishing in size, so as to be considerably 
 narrower at one end than the other. At the narrow end was 
 a lid with a stuffing-box, through which passed a rod attached 
 to a kind of piston inside the retort. Over this was a hopper, 
 capable of containing about 28 lbs. of coal, which w T as admitted 
 into the retort by drawing a slide or valve placed immediately 
 under the hopper. The retort being charged with coal, the 
 slide was shut, to prevent the escape of gas. 
 
 At the wide end of the retort was a shoot dipping into a 
 cistern of water, to prevent the gas escaping at that point. 
 The coal being carbonised, the coke was forced forward by 
 means of the piston, and dropped through the shoot into the 
 cistern of water, from whence it was removed either by rake, 
 shovel, or endless chain of buckets. The piston w r as again 
 withdrawn to the narrow end of the retort, ready for another 
 charge. 
 
 Mr. Brunton claimed great superiority for this description 
 of retort, and about 1840 it excited considerable attention, 
 was tried in several places, but was not a success. 
 
ON THE RETORTS USED IN GAS MAKING. 
 
 93 
 
 Mr. George Lowe about the same period introduced his 
 reciprocating retorts. In this system the retorts were con- 
 nected together in pairs, w T ith suitable valves. The object 
 of this was, that “ the products alternately of one of two 
 retorts should be caused to pass into and mix with the pro- 
 ducts of the other retort ; by which means, whichever of the 
 two retorts w 7 as last charged, the products thereof, during 
 the early part of the working, should pass into the other 
 retort,” which, being in a highly heated state, would decom- 
 pose any tar that might pass, and convert it into gas. This 
 system, after being tried for some time at the Pancras station 
 of the Imperial Gas Company, was abandoned. 
 
 Mr. Clegg introduced a system of retort which w T as remark- 
 able for its ingenuity. This consisted of a kind of endless 
 chain of fire-bars, caused to travel by means of two re- 
 volving cylinders set in motion by steam power, in principle 
 very similar to Jukes’s self-consuming smoke apparatus or 
 furnace ; the whole of this was enclosed, and the upper 
 part of the chain exposed to the action of a high heat. The 
 coal entered by a hopper, and fell on the web or chain, and 
 by the motion of this, was carried to the point of distillation ; 
 which done, the coke by the same motion was caused to drop 
 into the receptacle destined for it. 
 
 Mr. Clegg’s statement of the process with reference to the 
 specific gravity and quantity of the gas was rather extra- 
 ordinary ; but his assertion that the plates absorbed carbon, 
 and were so converted into steel, was decidedly erroneous. 
 
 There are two kinds of retorts employed in the gas manu- 
 factory, viz. those of fire-clay, and those of cast iron, and in 
 rare cases they are constructed of fire-bricks, built in the 
 manner of an oven. Ketorts are single or double : the single 
 retort is closed at one end, and generally from 7 ft. to 9 ft. 
 long; the double retort is open throughout, and is charged 
 simultaneously at both ends. 
 
 They are very variable in their shape, being cylindrical, 
 elliptical, in the form of the letter I), &c., depending on the 
 judgment of the engineer. 
 
 Formerly cast-iron retorts were universally employed in 
 gas-works ; at present they are almost entirely superseded by 
 
94 
 
 THE MOUTH-PIECE. 
 
 those of fire-clay. Iron retorts exist now only in very small 
 works, or when combined with settings of clay, hereafter 
 mentioned. 
 
 The iron retort, when now used, is the D shape, and 
 single, being about 7 feet G inches long, 15 inches wide, and 
 13 inches high, interior measure, of the uniform thickness of 
 If inch throughout, and weighing about 16 cwt. There is a 
 flange on its end, corresponding to the flange of the mouth- 
 piece, to which it is attached by bolts and nuts, and the joint 
 made perfectly secure with cement. 
 
 THE MOUTH-PIECE. 
 
 The mouth-piece may be considered a continuation of the 
 retort; but not being embedded in the brickwork, is not 
 exposed to the same degree of heat as that, nor is it instru- 
 mental in the distillation of the coal. 
 
 The mouth-piece is usually about 10 or 12 inches long, 
 having the same form as, but being considerably thinner 
 
 than, the retort to which it is attached. There is a socket or 
 flange cast thereon, to receive the end of the ascension pipe, 
 
THE MOUTII-PIECE. 
 
 95 
 
 which conveys the gas to the hydraulic main. There are 
 also two pieces called ear -boxes, to which are fixed the 
 ears for supporting the door, or as sometimes called, the lid 
 of the mouth-piece. The cross-piece or screw-key is sup- 
 ported by the ears, and when the retort is charged the lid 
 has a layer of luting around it, and by means of the screw 
 the joint is made hermetically tight. 
 
 Figs. 4 to 8, drawn to a scale of -r 2 -th, or one inch to a foot, 
 show details of a flanged mouth-piece for a D retort. Fig. 4 
 is a longitudinal section of mouth-piece, showing the socket 
 cast on it to receive the ascension-pipe, and the lid affixed to 
 
 the mouth. Fig. 5 is a corresponding elevation, showing the 
 ear-box a, cast on each side of the retort to receive the ears, 
 which are usually 14 inches long. Fig. 6 is a front elevation, 
 showing the mouth -piece attached to the retort, but without 
 the lid of the mouth-piece. Fig. 7 is a side elevation, and 
 Fig. 8 is a plan of the mouth-piece attached to the retort, 
 showing also the lid and the mode of securing it to the 
 mouth-piece, b b are the ears passing through the ear- 
 boxes a a , and secured by cotters, c c. d is the cross-bar 
 through which passes the screw e, which presses on the lid 
 and firmly secures it to the mouth -piece. The ears b b are 
 
90 
 
 THE MOUTH-PIECE. 
 
 fixed, and the mode of removing the door of the retort is 
 by unscrewing the key, when the cross-bar d can be taken 
 
 away and the door lifted off. The luting usually employed 
 for the edges of the mouth-pieces is a composition of lime- 
 
 mortar and fire-clay or loam, which, on being compressed 
 by the screw, makes a perfectly gas-tight joint. 
 
 There are various modifications of the parts connected 
 with the lid, which may be briefly noticed. Sometimes the 
 ear -boxes are so cast as to have no top, in which case they 
 
THE MOUTH-PIECE. 
 
 97 
 
 form a simple rectangular notch cast on each side of the 
 moutli-piece. The ears, again, are not always perforated 
 with the holes to receive the ends of the cross-bar, but have 
 sometimes a simple notch in which the ear-bar rests. 
 
 There is another method of fastening the lid, in which 
 
 Fig. 10. 
 
 the screw is altogether dispensed with, as shown in Figs 
 9 and 10. 
 
 Here the ears form supports for an axis, a, which carries 
 a lever formed at one extremity into a sort of eccentric or 
 
98 
 
 IRON RETORTS. 
 
 cam, and carrying at the other end a globe of solid cast iron 
 about 4 inches in diameter. When the globular end of this 
 lever is depressed, the cam presses with considerable force 
 upon the back of the lid, and holds it as effectually in its 
 place as the screw : in addition to which, if required, it is 
 easy to increase the pressure by hanging on to the globular 
 end of the lever an iron ring or other weight. 
 
 Fig. 11 represents a 
 door of a mouth-piece, 
 which is supported in its 
 position, and lifted, by the 
 lugs at the sides. These 
 were formerly of cast iron, 
 but are now of wrought 
 iron plate, about ^ inch 
 thick, and slightly hol- 
 lowed, to strengthen them. 
 This simple alteration is 
 of great importance, as it relieves the workman from lifting 
 a cumbrous weighty mass, which was one of the most difficult 
 parts of his duty. 
 
 IRON RETORTS. 
 
 For many years iron retorts were exclusively used, and 
 their general abandonment by gas-works has only occurred 
 within the last twelve or thirteen years. The evils arising 
 from' iron retorts are numerous : they are costly in them- 
 selves, which is increased by the expense in setting ; the 
 price of fire-clay materials, as tiles, shields, bricks for arches, 
 and labour, renders a bench of them expensive. Their dura- 
 bility is also very limited, averaging about seven or eight 
 months, and producing each about 600,000 or 700,000 cubic 
 feet of gas. The average production from clay retorts being 
 nearly four times that quantity. 
 
 After having been in operation some time, iron retorts 
 become bad conductors of heat, in consequence of the forma- 
 tion cf a coat of peroxide of iron on their exterior ncces* 
 
XR ON RETORTS. 
 
 99 
 
 sitating continued cleansing, which, however, can only be 
 effected in some parts of the retort, leaving the other parts 
 covered ; and it sometimes happens that the retort is em- 
 bedded in this non-conducting material, so that the heat 
 cannot penetrate to it. 
 
 Another evil is, that the iron becomes changed in its 
 molecular nature, losing considerably its powers of conducting 
 heat, and great care is requisite to protect them with fire- 
 tiles ; stout arches are built to prevent the direct action of the 
 heat on them. All this is a cause of a loss of fuel ; and with 
 these precautions, care must be employed to prevent them 
 attaining that degree of temperature which would be destruc- 
 tive to them : and this sometimes produces a contrary effect, 
 so that the temperature becomes too low, and a small yield 
 of gas, with excess of tar, is the consequence. 
 
 Iron retorts are only useful in small works, where the 
 holders are heavy, or where wet lime purifiers, plunge- 
 washers, and other circumstances exist which produce great 
 pressure, and where an exhauster is not used ; or when the 
 retort is continuously heated and cooled, as in experimental 
 apparatus, and auxiliary settings. 
 
 Iron retorts expand considerably, and after being worked 
 some time and cooled down, a 7 ft. 6 in. retort will be found to 
 have elongated about 3 inches. If this be put into operation 
 it will again expand, but not in so great a proportion ; how- 
 ever, it is not uncommon for a retort, as mentioned, which 
 has been repeatedly heated and cooled, to expand 5 inches in 
 length. Therefore, when used, the ovens of these should 
 be considerably longer than the retort, otherwise the pro< 
 liability is that the front wall of the oven will be bulged out. 
 
 When iron retorts are required for future use, previously 
 to being allowed to cool down the carbonaceous incrustation 
 in the interior should be removed ; should this be allowed 
 to remain, the retort sometimes breaks in tw r o halves, caused 
 by the iron contracting in a much greater degree than the 
 carbon. 
 
 When in separate beds from the furnace, as in the com- 
 pound settings of iron or clay, their durability is greatly 
 increased, being on the average from eighteen to twenty 
 
100 
 
 CLAY RETORTS. 
 
 months ; nor do they form the peroxide of iron with the 
 same facility, and this can be diminished to a minimum by a 
 very thin coating of fire-clay on the exterior of the retort. 
 
 CLAY RETORTS. 
 
 The adoption of clay retorts has undoubtedly been one of 
 the greatest improvements introduced into the manufacture 
 of gas. 
 
 As already stated, Mr. Winsor, in 1804, patented a “brick, 
 or earthenware retort or oven,” but it does not appear that 
 any application of this was made until 1818, when Mr. John 
 Grafton patented improvements “ in employing retorts lined 
 or cased with fire-clay.” In 1820 the same gentleman 
 obtained a patent for improvements in clay retorts; in this 
 specification he says, “ the Stourbridge clay heretofore used 
 for clay retorts had generally failed in consequence of these 
 retorts being made in one entire piece, which caused them 
 to break in pieces very shortly after the fire was applied ; ” 
 it continues, “ I caused the retort to be made in several 
 pieces,” which, indeed, seems to have been the object of 
 Mr. Grafton’s invention, and the substance of the specifica- 
 tion leads us to believe that clay retorts were being tried 
 previously to this; but if it were so, it must have been 
 on a very limited scale, for neither the works of Accum 
 nor Peckstone, published in 1819, mention anything about 
 them. 
 
 It is not very material whether Mr. Grafton was the first 
 or not to introduce clay retorts ; it is, however, certain that 
 he has been the direct means of bringing them into general 
 use, for during several years, at great risk and loss, he tried 
 various systems in order to ensure success. Amongst these 
 was the mode of constructing the retort entirely of fire- 
 bricks, built together with fire-clay ; these were in the shape 
 of Fig. 12, about 5 feet 6 inches wide and 7 feet long, and 
 capable of distilling from 7 to 9 cwt. of coal at each charge. 
 This description of retort was in operation for many years 
 in several parts of the Continent, where they had been 
 
CLAY RETORTS. 
 
 101 
 
 erected by Mr. Grafton. The advantages they possessed 
 were a diminution of labour in charging and discharging, 
 
 and the coke from them was of a good heavy quality, suitable 
 for foundries, &c. ; but on the other hand they were very 
 costly in their construction, and required a large quantity of 
 fuel for carbonisation. 
 
 The fire-brick retorts of Messrs. Spinney and Clift, 
 described in the former edition of this treatise, were very 
 similar to those just mentioned. 
 
 Mr. Grafton afterwards had these retorts made in four or 
 five pieces, similar to the plan now very generally adopted, 
 going back to his original idea according to the specification 
 quoted. 
 
 Clay retorts were worked in Scotland for some years 
 previously to their employment in England ; they were first 
 applied in consequence of the high heats and short charges 
 necessary in the distillation of cannel coal, which destroyed 
 the iron retorts very rapidly, unless they were well pro- 
 tected with fire-clay materials, so making the settings very 
 costly. The first great trial of clay retorts in London was 
 made by Mr. Croll, at the Brick-Lane Station of the Char- 
 tered Company, in 1843. The retorts did not, however, 
 answer the expectations ; they cracked, allowing the gas to 
 escape, and this was considered by many at the period as 
 being a fatal objection to their use. 
 
 In 1844 Mr. Joseph Cowen, of Newcaetle-on-Tyne, ob- 
 tained a patent for making clay retorts by a new and novel 
 method, and for combining with the clay destined for the 
 retort various substances, such as pounded coke, charcoal, 
 
102 
 
 CLAY RETORTS. 
 
 sawdust, &c., which project, beyond doubt, led the way to 
 the present perfection in this branch of manufacture. Pro- 
 bably the idea of Mr. Cowen was that the substances above- 
 named would continue in combination with the retort, when 
 in operation ; but the reverse of this took place, for in the 
 course of time the carbonaceous matter so incorporated 
 burned away, leaving the vessel porous ; but retorts made 
 in this manner did not crack or break by the heat. 
 
 The knowledge of this fact led to trials with other sub- 
 stances intermixed with the clay, and finally to the present 
 system, which is as follows : — In manufacturing clay retorts 
 a portion of fire-clay is burned and reduced to a granulated 
 state; this is then intermixed with just sufficient clay to hold 
 the mass together ; the retort is then made by hand — allowed 
 to dry very gradually — and then burned. The retorts so 
 made, although much inferior in appearance to those of clay 
 alone, are all that can be desired. From some peculiarity 
 in the Scotch fire-clay this manipulation was not at first 
 followed; the retorts made therefrom answered the object 
 tolerably w r ell ; but those from Newcastle clay, without the 
 granulated burnt clay, will not withstand the heat, for with 
 all the care imaginable in firing they crack and break into 
 numerous pieces. 
 
 The advantages of clay retorts are — firstly, their great 
 durability ; secondly, the degree of heat to which they may 
 be submitted, which would be destructive to iron, is more 
 suitable for carbonising the coal, producing the greatest 
 quantity of gas, with little tar, and coke of good quality ; 
 lastly, they require less labour. These important points 
 have contributed much to the present economy in the pro- 
 duction of gas, and the success of gas enterprises. 
 
 For some years, however, great prejudice existed against 
 the use of clay retorts ; an animated correspondence took 
 place in the columns of the Journal of Gas-Lighting between 
 two gentlemen of eminence, the one in favour, the other 
 against them. The arguments unfavourable were, that clay 
 being a bad conductor of heat, would require more fuel for 
 the carbonisation of a given quantity of coal ; that the mate- 
 rial being porous, the gas would escape to the atmosphere 
 
CLAY RETORTS. 
 
 103 
 
 instead of going to the holder ; and that by the high heat 
 of clay retorts, the rich hydrocarbons would be deposited 
 therein as incrustation. However, in working, experience has 
 refuted all these objections, and the vast superiority of clay 
 retorts is now universally demonstrated and admitted, not 
 only in this country, but on the Continent and in America. 
 
 But clay retorts cannot in most cases be worked advan- 
 tageously without an exhauster to withdraw the gas the 
 instant it is produced, to prevent it remaining under pres- 
 sure, exposed to the red-hot surface. Should the exhauster 
 not be employed, and the pressure in the retort be con- 
 siderable, the heavy hydrocarbons are deposited in great 
 abundance, deteriorating the value of the gas, generating a 
 non-conducting material, which obstructs the interior of the 
 retort, and demanding more fuel for carbonising. 
 
 The objection that the clay of retorts is so porous as to 
 permit the gas to pass through, is erroneous, which any one 
 may be convinced of by breaking one of them which has 
 .been in use for any length of time, when it will be found that 
 the carbon has perhaps penetrated to the depth of one half 
 or three-quarters of an inch, but shows no signs of having 
 traversed the material. There are, however, some slight 
 fissures or fire cracks which exist in the manufacture, which 
 are speedily stopped after the first two or three charges ; but 
 generally clay retorts of good construction, when the exhauster 
 is applied, are not more porous than the best of iron. 
 
 As regards the objection that clay is a worse conductor of 
 heat than iron, no one will dispute this ; but the opponents 
 of clay retorts did not take into account the vast quantity of 
 this non-conducting material which was employed for the 
 purpose of protecting the iron retorts, nor did they consider 
 the quantity of non-conducting material continually being 
 formed on their exterior. If this had been duly weighed, 
 clay retorts would have had considerably less opposition. 
 
 Although the manufacture of clay retorts would appear a 
 very simple process, there is a peculiarity of manipulation in 
 preparing and tempering the clay, and in constructing the 
 retort, which, if not strictly adhered to, results in failure. 
 In first-class fire-brick works a surprising amount of care is 
 
104 
 
 CLAY RETORTS. 
 
 taken with the clay, which when extracted from the mine is 
 not considered suitable for the purpose until it has been 
 exposed for many months, and sometimes years, to the action 
 of the atmosphere, which acts chemically on it, and renders 
 it suitable for the object intended. Thus, at the extensive 
 works of Messrs. J. Cowen & Co. of Newcastle-on-Tyne, and 
 probably at many others, there are mounds of some thousands 
 of tons of clay undergoing this process, and to this circum- 
 stance may very likely be due the excellence of the goods for 
 which that house is celebrated. 
 
 Clay retorts are as variable in their form as the iron ones 
 were. Scotch engineers generally prefer them circular ; on 
 the Continent the elliptical are almost universal ; whilst in 
 England no definite conclusion on this point has been formed, 
 their size and shape depending on the views of the respective 
 engineers, and not on any positive grounds. 
 
 In London the retorts usually employed are the D-shaped, 
 with the corners rounded, otherwise, if square, the increased 
 and uneven thickness would cause them to crack at that part. 
 The form and size universally employed on the Continent is 
 the oval, about 1 foot 8 inches wide, 1 foot 1 inch high, from 
 7 to 9 feet long, and invariably made in one piece. 
 
 The D shape may be slightly preferable on account of the 
 layer of coal when placed therein being of one uniform 
 thickness ; against this, probably the circular and oval, being 
 of greater regularity in their thickness, are not so liable 
 to break. 
 
 At most large gas-works double clay retorts are used. 
 These are from 18 to 20 feet long, composed usually of four 
 or six distinct pieces, jointed together with fire-clay, having 
 a mouth -piece at each end, and are combined in sets of six, 
 seven, eight, or ten. 
 
 At the Imperial Company’s works there is considerable 
 economy of space in the retort-house, by placing ten retorts 
 in an oven, in two vertical rows. The upper retorts are 
 charged and discharged by means of a travelling stage. 
 Each of these double beds is capable of carbonising from 7 ^ 
 to 8 tons of coals, producing from 70,000 to 75,000 cubic 
 feet of gas per day. In the same space, with iron retorts 
 
CLAY RETORTS. 
 
 105 
 
 and old settings, of five retorts in a bench, little more than 
 one-third of this result would be obtained. 
 
 Clay retorts, like those of iron, are of uniform thickness 
 throughout, averaging about 2J to 2| inches. Their mode 
 of setting is remarkably simple, requiring no guard or shield 
 tiles, and in some cases have no arches, which formerly were 
 great obstacles to the distribution of the heat. The mouth- 
 pieces of clay retorts are precisely similar to those of iron, 
 but the sockets and the ascension-pipes are required larger ; 
 the latter for clay retorts should never be less than 5 inches 
 internal diameter. 
 
 Fig. 13 shows the open end of a clay retort, and Fig. 14 
 
 shows the mode of attaching the mouth-piece by means of 
 bolts with T-heads let into the body of the retort. 
 
 Fig. 13 is a front elevation of the retort, showing the 
 thickness of the part to which the mouth-piece is bolted, also 
 the bolt-holes, 1^- inch in diameter. 
 
 Fig. 14 is an elevation showing the mouth-piece attached, 
 with a socket-pipe bolted on, but without the lid, and is 
 similar in its details to that shown for iron retorts. 
 
 Fig. 15 is an end elevation of one of the pieces of which 
 F 3 
 
106 
 
 OLAY RETORTS. 
 
 the retort is composed, showing the triangular groove of a 
 corresponding ring, for the reception of the fire-clay when 
 making the joint ; and 
 
 Fig. 16 is a section showing the junction between two 
 pieces of the retort. 
 
 In making the joints of clay retorts, or attaching the 
 mouth-pieces to them, the part of the retort should be well 
 
 wetted, so as to combine with the clay. For connecting 
 together the ends of clay retorts, fire-clay alone is used, 
 formed into the state of mortar. For the joints of mouth- 
 pieces, a small portion of iron cement is often intermixed 
 with the fire-clay. It is essential that these retorts should 
 be allowed to remain a few days after being set, before 
 being fired, to expel any moisture, which would be likely to 
 cause them to crack. The breakage of clay retorts is occa- 
 sioned sometimes by the stoker failing to apply a light, when 
 in the act of discharging, as soon as the lid is loosened ; the 
 
CLAY RETORTS. 
 
 107 
 
 consequence is, the gas in the retort becoming combined with 
 air, an explosion is produced, which shatters the retort. 
 
 In first-class manufactured clay retorts, when an exhauster 
 is employed, leaving only a pressure of about an inch on 
 them, there is no leakage whatever. In others, of inferior 
 
 make, the leakage will sometimes be considerable ; but this, 
 in the course of a short time, is stopped by the carbon of the 
 gas itself, which is deposited in the cracks and fissures ; these 
 arising from fire-cracks, and not from the porosity of the 
 material. 
 
 In England clay retorts for the sake of strength are gene- 
 rally supported in their ovens at intervals throughout, by 
 walls, as seen in Fig. 19. On the Continent these are always 
 dispensed with — the retorts, usually made in one piece of 
 8 or 9 feet long, only being supported by the pillars on 
 which they are placed. 
 
 In attaching the mouth-pieces to iron retorts, or the ascen- 
 sion pipe to the mouth-pieces, &c., the ordinary iron cement 
 should be employed ; this is driven in by means of a caulking- 
 iron, and when properly done makes a good sound joint, but 
 is never suitable when exposed to even a very low degree of 
 red heat, for under these circumstances the cement is decom- 
 posed, and becomes useless. 
 
108 
 
 CLAY RETORTS. 
 
 The recipes for making iron cement vary considerably 
 Mr. Peckstone says 1 lb. of iron borings or turnings are to b 
 pounded in a mortar into a state of fine dust or powder ; 
 these are to be mixed with 2 oz. of sal ammoniac in powder 
 and 1 oz. of flour of sulphur ; the whole to be thoroughly 
 incorporated by being pounded in a mortar. When required 
 for use, take one part by measure of the above compound, and 
 mix it with twenty parts of pounded iron borings, adding 
 water to bring the mixture to the consistence of ordinary 
 mortar. This cement may be applied in making all sorts of 
 flange joints, as in securing the mouth-pieces to the retorts, 
 the dip-pipes to the hydraulic main, &c. 
 
 Mr. Clegg’s recipe is somewhat different : he uses 
 
 Iron borings or turnings 32 oz. 
 
 Sal ammoniac 1 „ 
 
 Hour of sulphur 1 „ 
 
 To be well mixed together, and kept dry for use. When 
 required, water to be added to bring the mixture to a proper 
 consistency. 
 
 The French employ for the same purpose a cement called 
 the Mastic d’Aquin, which is thus prepared : — 
 
 98 parts of clean iron turnings, pounded and passed through 
 a sieve. 
 
 1 part of flour of sulphur. 
 
 1 part of sal ammoniac, dissolved in sufficient boiling water 
 to bring the whole mass to the consistency of ordinary 
 mortar. 
 
 This cement is not prepared till required for use, and should 
 be employed as soon as possible. The iron borings should 
 be sifted, and perfectly free from grease or oil, otherwise if 
 too granulated or greasy a good joint cannot be made. 
 
ON RETORT SETTINGS. 
 
 109 
 
 CHAPTER VIII. 
 
 ON RETORT BETTINGS. 
 
 The disposition of the retorts in the ovens, or the manner 
 they are placed or set, is called the “setting,” and the judicious 
 arrangement of this part of the apparatus in gas manufacture 
 is of the utmost importance ; for on this mainly depends 
 alike the economical production of gas, and the use of the 
 minimum quantity of coke as fuel. 
 
 Setting retorts comprises the construction of the ovens and 
 furnaces ; properly placing, supporting, and protecting the 
 retorts ; arranging the passages between them so as to equalise 
 the heat throughout; and making the communication with 
 the main flue. To approach perfection in this, there are 
 several points to be considered. 
 
 The foundations of the retort ovens should be solid and 
 sufficiently massive to prevent the loss of heat at that part. 
 Sometimes a series of air-cells or small spaces in the brick- 
 work of the foundations are formed in order to prevent loss 
 of heat by radiation. All superfluous brickwork in the inte- 
 rior of ovens should be avoided, leaving only that necessary 
 for the proper support of the retorts, and, when iron retorts 
 are used, the proper protection to guard them- from the 
 injurious action of the heat. Other means to prevent the 
 radiation of heat should, so far as practicable, be adopted ; 
 for all heat lost unnecessarily by radiation is so much coke 
 lost without a purpose. The openings or nostrils for distri- 
 buting the heat from the furnace should always be amply 
 wide. Many instances have occurred where the furnace has 
 been at an intense degree of temperature, yet the retorts 
 above could not attain an ordinary heat on account of the 
 passages or nostrils being contracted. An essential point 
 also is to have complete control over the damper leading to 
 the flue ; for if this be too much open, and the draft strong, 
 a great increase of fuel is necessary without any good result. 
 Lastly, whilst due consideration should be had for the com- 
 forts of the stokers employed, all useless loss of heat in the 
 
110 
 
 ON RETORT SETTINGS. 
 
 retort-house should be prevented, so that the buildings should 
 not have too many openings, as windows, &c. ; and when air- 
 shafts or ventilators are constructed, these should be provided 
 with valves, to shut or close according to the weather, or the 
 season of the year. 
 
 Formerly in the construction of furnaces for gas-works the 
 steam-boiler furnace was copied, this being of large area, 
 and the fuel placed in a thin layer ; but the conditions of the 
 two are widely different. A large area and thin stratum is 
 well adapted for burning coal and generating steam ; but the 
 reverse of this is requisite for burning coke and obtaining 
 that high degree of temperature essential for retorts. It is 
 now generally acknowledged that when the furnace is con- 
 structed so as to heat comparatively a small quantity of air 
 to great intensity, which afterwards diffuses itself, the best 
 results are obtained. 
 
 Fig. 17 shows a section of a furnace of this kind, which 
 was first employed by Mr. Croll twenty years ago, and has 
 since become very general. They are of small area, being 
 
 at the bottom from 20 to 30 inches long, from 6 to 9 inches 
 wide, and from 10 to 18 inches deep, depending on the size 
 of the ovens to which they are attached, the smallest dimen- 
 sions stated being sufficient for a bed of five retorts. 
 
ON SETTING CLAY RETORTS. 
 
 Ill 
 
 There are two bearers of wrought iron built into the 
 brickwork, a short distance from the ends, and on these 
 repose the fire bar or bars. In small furnaces one bar only 
 is used, in large furnaces two are generally employed. These 
 are simply bars of wrought iron of 1| to 2 inches square, placed 
 loosely on the bearers. By this system the air passes through 
 a thick stratum of fuel, and attains an intense heat ; whereas 
 by the old furnace often a large portion of air passed through 
 the uncovered bars without contributing to the heat, but, on 
 the contrary, carrying with it a portion of that from the 
 retorts. Great facilities for “ clinkering” are offered by this 
 manner of placing the bars, so that they can easily be shifted, 
 the clinker removed, and afterwards, when replaced, a few 
 lumps of coke are thrown in to prevent the smaller pieces of 
 coke from falling through the openings between the bars, 
 which done, no more breeze passes through than with the old- 
 fashioned method. These furnaces are now very generally 
 employed, and are undoubtedly superior to others. 
 
 ON SETTING CLAY RETORTS. 
 
 In setting clay retorts there is not that degree of difficulty 
 which exists with those of iron ; the complication of fire-tiles, 
 shields, and protecting arch, are avoided. The retorts being 
 placed on proper pillars or supports, the fire from the furnaces 
 acts directly upon them. 
 
 There is great diversity of opinion as to the best mode of 
 setting, some engineers preferring six, others seven, eight, 
 nine, and even ten retorts in a bed. Nor does this diversity 
 of opinion confine itself to the number, but applies also to the 
 mode of conducting the heated air. In some cases this passes 
 direct into the main flue above, in other instances the heated 
 air passes over the retorts above, and then descends into the 
 main flue below ; but as the two methods are practised in 
 our metropolitan w 7 orks, it may be inferred that there cannot 
 be much difference in their results. 
 
 Fig. 18 represents a section of a bed of ten clay retorts, as 
 used at the Imperial Company’s works. In this setting there 
 are ten double retorts, each 18 feet long, and charged at both 
 
112 
 
 ON SETTING CLAY RETORTS. 
 
ON SETTING CLAY RETORTS. 
 
 113 
 
114 
 
 ON SETTING CLAY IlETOItTS. 
 
 ends simultaneously. The upper retorts are charged, and 
 drawn by means of a travelling stage, which is wheeled from 
 one end to the other of the retort-house, wherever required. 
 a is the furnace, having one bar only ; r r the retorts ; b is 
 the flue conducting to the main flue, there being various 
 openings throughout the whole length for the heat to pass 
 freely. The ordinary charge for this setting is 1 ton 16 
 cwt., which is sometimes carbonised in five hours, but more 
 generally in six hours. 
 
 Fig. 19 is a section of half a double setting of these retorts 
 through the vertical line a b, the front wall and mouth-piece, 
 for want of space, not being shown. It, will be observed that 
 the brickwork is merely for supporting the retorts, and that 
 the fire acts direct, without any interruption, ascending to 
 the main flue above. These beds are fired with the red-hot 
 coke as drawn from the retorts, producing a considerable 
 economy. 
 
 The general opinion is in favour of settings of seven clay 
 retorts in a bed ; and where economy of space in the retort- 
 house is not so necessary as at the Imperial Company’s works, 
 the settings of seven may be preferable, on account of the 
 whole of the retorts being worked from the ordinary firing 
 floor, and not requiring the travelling stage. 
 
 Fig. 20 represents a front section of a set of seven clay 
 retorts as adopted at the Commercial Company’s works in 
 London. In this the heated air diffuses amongst the upper 
 retorts, and afterwards descends into the main flue below. 
 The variation in the two systems of upward and downward 
 current cannot be important, otherwise the results would 
 speedily settle the division of opinion as to their respective 
 merits. 
 
 The price of a setting of single retorts, including founda- 
 tions, oven, furnace, door, frame, ash-pan, fire-bars, buck- 
 staves, sight boxes, retort, mouth-piece, two lids, ascension, 
 bridge, dip-pipes, and hydraulic main — in short, the bed 
 complete, with all its accessories — is generally estimated at 
 £17 10s. per retort, so that a bed of seven single retorts, 
 each 8 feet 6 inches long, will cost about £122 10s. The 
 average durability of good clay retorts may be considered 
 
ON SETTING CLAY RETORTS. 
 
 115 
 
 about two and a half years, during which time the expense 
 for fire-bars, repairs to furnace, &c,, will not exceed 20s. per 
 retort. The duration of retorts in some of the London works 
 is often four and even five years. 
 
 The arch of ovens once properly built will last sever. 1 
 years. Taking down retorts, and replacing them with new 
 
 Fig. 20. 
 
 ones, including labour, materials, &c., averages £7 10s. per 
 retort ; so that replacing a setting of seven clay retorts would 
 cost about £52 10s. When double retorts are used, the 
 same estimates per mouth-piece are applicable. 
 
116 
 
 IRON RETORT SETTINGS. 
 
 The cost of wear and tear of clay retorts in a medium size 
 works may be estimated at 1 d. per thousand feet of gas pro- 
 duced. In large establishments it will be considerably less 
 than this. 
 
 IRON RETORT SETTINGS. 
 
 Among the various attempts to improve the working of 
 ordinary iron retorts has been the system of subdividing them 
 into two distinct longitudinal compartments, with the view that 
 any tar that might be formed during carbonisation in the 
 lower part would, in passing through the upper chamber, be 
 converted into gas. This, however, would have the same 
 inconveniences which accompany the production of gas from 
 tar in the ordinary manner, and described elsewhere, with the 
 inconvenience that the hydrocarbons of the gas would be 
 deposited by their prolonged contact with the red-hot retort. 
 
 It has also been proposed to construct iron retorts with 
 projecting ribs in the interior, for the purpose of increasing 
 the surface ; but this, instead of being beneficial, has tended 
 to encourage the incrustation of carbon. Another method 
 was to glaze iron retorts both internally and externally, which 
 process possessed the advantages that the non-conducting 
 material was not so rapidly formed on the exterior, and the 
 incrustation of carbon was removed with great facility from 
 the interior. These and many other systems have been 
 patented from time to time ; but as clay retorts became 
 gradually introduced, so was their great superiority under- 
 stood, and iron retorts abandoned. 
 
 Iron retorts are only useful in very small works, where 
 there is no exhauster, and the pressure is too heavy for 
 clay ; or when the settings, as auxiliaries, are subject to 
 being in operation for a short period, and afterwards cooled 
 down, which would cause clay retorts to crack and be useless ; 
 or for experimental purposes, — in these cases they may be 
 used with advantage. 
 
 When circumstances oblige the use of iron retorts, imme- 
 diately over the furnace there is an arch or fire slab, forming 
 a kind of table or “ bench ” to receive the retorts. At each 
 side of this there are openings for the heated air to pass and 
 
IRON RETORT SETTINGS. 
 
 117 
 
 
 iii r 
 
 
 ■ i ^ „ I 
 
 : I i IPP 
 
 
 ' £ . 1 j__ 
 
 i 
 
 
 ._ _. . .. J .-- v 
 
 i - i I I i 
 
 
 diffuse itself throughout the bed, also fire-tile shields to pro- 
 tect the retorts from the direct action of the fire. 
 
 The accompanying Fig. 21 is a section of a bed of three 
 iron retorts, f is the furnace, c the interior of oven, R r r 
 the retorts, b b the fire slabs forming the table or bench, a a 
 
118 
 
 IRON RETORT SETTINGS, 
 
 the shields for protecting retorts from direct action of fire, 
 d the supporting pillars, e small flue, fff the nostrils for the 
 passage of the fire, g the damper, this being a kind of valve 
 formed of fire-bricks and a fire- slab. 
 
 Fig. 22. 
 
METHOD OP COMBINING CLAY AND IRON RETORTS. 119 
 
 Fig. 22 is a longitudinal section of the same, with the cor- 
 responding letters of reference ; the front wall for want of space 
 is not shown ; c is the back wall, which divides the two fur- 
 naces when they work back to back. When in single beds this 
 wall requires to be of good thickness, to prevent loss of heat. 
 
 It is almost unnecessary to say that all parts in immediate 
 contact with the fire should always be of good fire-bricks, for 
 at least a thickness of 9 inches, built with fire-clay, and as 
 thin joints as possible, the bricks being previously moistened. 
 The furnaces should be constructed of the best bricks that 
 can be procured for the purpose. Some descriptions of Stour- 
 bridge bricks, others of Wales, called “ Dinas” bricks, are 
 reputed to be good for the purpose. 
 
 The radiation of heat from the tops of the arches may be 
 greatly prevented by having a good thickness of brickwork, 
 or a layer of sand, ashes, or similar non-conducting material, 
 which is covered by a course of bricks. The front walls 
 of ovens should never be less than 14 inches thick ; and 
 when beds in use adjoin those out of action, the latter should 
 be closed in all their parts ; the mouths of the retorts, the 
 furnace door, and ash-pit bricked up, and the sight holes and 
 damper securely luted with clay. The end bench of a setting 
 has generally a massive wall as a buttress, which likewise 
 prevents radiation at that point. The beds are also securely 
 tied together by tie-rods and buckstaves. 
 
 The following chapter will assist the reader to understand 
 more fully the practice of setting retorts. 
 
 CHAPTER IX. 
 
 METHOD OP COMBINING CLAY AND IRON RETORTS. 
 
 1 
 
 The first conception of combining clay and iron retorts, so 
 that the surplus heat from the former should afterwards be made 
 available for the latter, is due to Messrs. Kirkham and Lowe ; 
 but they appear not to have been cognisant of the import- 
 ance of the system, and it was neglected, if not forgotten. 
 
120 METHOD OF COMBINING CLAY AND IRON RETORTS. 
 
 A short period afterwards Mr. Croll, unacquainted with 
 what had been conceived by these gentlemen, patented a 
 
 similar system, and with the means of properly carrying it 
 to a successful issue. 
 
METHOD OF COMBINING CLAY AND IRON RETORTS. 121 
 
 In applying clay retorts to the carbonisation of coal, they 
 are submitted to a much higher degree of heat than those 
 of iron : the average temperature of the former being about 
 2100° Fahr., or an orange red ; whilst those of iron work 
 most effectively at cherry red, or about 1700° Fahr. There- 
 fore, it is obvious that the waste heat of clay retorts would 
 be available for iron retorts. 
 
 When clay retorts alone are employed, the surplus heat 
 passes into the atmosphere and is lost ; but when combined 
 with iron, as hereafter explained, this heat is made available, 
 and is ample to maintain iron retorts at the proper degree of 
 temperature alike for the economical production of gas and 
 coke, thus effecting a very considerable economy in the fuel 
 for carbonisation. This principle of combining clay and iron 
 retorts has for a period of years engaged the attention of 
 Mr. Croll, and under his management has been very success- 
 fully applied ; but, like many other great innovations, has 
 not met with the general approbation it merits, and, if we 
 reflect on the time required to develop the superiority of 
 clay retorts, this will occasion no surprise. 
 
 Figs. 23 and 24: demonstrate the system of this improve- 
 ment in the simplest form as in operation in small works. 
 c is the furnace, the fire of which communicates directly with 
 the three circular clay retorts above (r r r) ; and, after 
 acting on these, passes over to heat the two O iron retorts 
 (r' r'), and so to the flue i. Fig. 24: is a longitudinal section 
 of the same setting, with corresponding letters to indicate 
 the various parts. 
 
 Another modification, varying slightly from the former, is 
 shown in the Figs. 2 5 and 26. In this the clay retorts are 
 immediately over the furnace, and the iron retorts at the sides. 
 
 Figs. 27 and 28 represent a setting of this class for 
 works of larger capacity. In this bench there are five clay 
 retorts, each 7 feet 6 inches long, marked r, r, and four iron 
 retorts of the same length, besides one O retort, 5 feet long, 
 20 inches wide, and 20 inches high, marked r' in Fig. 28. 
 
 Through the courtesy of the editor of the Artisan , who has 
 kindly permitted me to copy the admirable plates published 
 in that journal, I am enabled to give, in Figs. 29 to 32, an 
 
 Q 
 
r ■” 
 
 122 METHOD OF COMBINING CLAY AND IRON RETORTS. 
 
 elevation, cross section, and longitudinal sections of one of 
 
 Mr. Croll’s ovens, showing the mode of combining iron and 
 
 Fig. 25. Kg- 26. 
 

 METHOD OF COMBINING CLAY AND IRON RETORTS. 123 
 
 Fig. 27. Fig. 28. 
 
124 METHOD OF COMBINING CLAY AND IRON RETORTS. 
 
 clay retorts, as prac tised by him on a very large scale. These 
 figures are all on a S3ale of 1 inch to 4 feet, a a a, &c., aro 
 
 Fig. 29. 
 
 the clay retorts, of which the upper two are elliptical, 18 
 
METHOD OF COMBINING CLAY AND IRON RETORTS. 125 
 
 inches by 15 inches, and the other four circular, 15 inches in 
 diameter inside. Each clay retort is made in four pieces, whicli 
 
 Fig. 30. 
 
 are jointed together with fire-clay, as described elsewhere, b b 
 are the furnaces at each end of the retorts, which are ranged 
 
126 METHOD OF COMBINING CLAY AND IKON RETORTS. 
 
METHOD OF COMBINING CLAY AND IRON RETORTS. 127 
 
 Fig. 32. 
 
128 METHOD OF COMBINING CLAY AND IRON RETORTS. 
 
 bo as to receive an equal share of the heat which diffuses 
 it3elf in the upper oven, c c c c, <fcc., are the iron retorts, 
 set in the lower oven, which receive the heated air through 
 the openings l l in the lower arch, d d d, &c., are the 
 ascension pipes, which pass up from each end of the clay 
 retorts, and from one end only of those of iron, f f are 
 columns which support the hydraulic main. Projections 
 cast on these columns support the girders h h, which are 
 destined to carry the firing floor ; i i are the evaporating or 
 ash-pans ; k k are the walls which carry the retorts, per- 
 forated with holes to allow the heated air to pass ; 1 1 are 
 the openings or nostrils which admit the heated air from the 
 upper to the lower oven; mm are the openings from the 
 lower oven into the horizontal flues n n , which are provided 
 with fire-tile dampers to adjust the draught. The horizontal 
 flues lead to the chimney, o o are flue-doors for cleaning 
 out the horizontal flues ; the whole being drawn to a scale 
 which accompanies Fig. 32. 
 
 Fig. 29 is a front elevation of this setting of retorts. 
 Fig. 30 is a transverse section of the same ; and Figs. 31 
 and 32, being jointed together at the line x, which is the top 
 of the lower arch, and is common to both figures, will form a 
 longitudinal section at right angles to the face of the bench. 
 
 It will be observed from the description given of this method 
 of setting that, independently of the use of clay retorts in com- 
 bination with iron, and the consequent change in the con- 
 duction of heat, there is an important variation from the 
 earlier system. 
 
 According to the old method massive brickwork and tiles 
 obstructed the passage of the heat, preventing its radiation 
 through the setting. This was a serious obstacle, which is 
 entirely removed in the combination settings, where the fire 
 impinges directly on the clay retorts, and, after losing a por- 
 tion of its intensity, passes to heat those of iron. By this 
 method the iron retorts have a greatly increased durability, 
 the average being about eighteen months. If, previously to 
 setting, they have a thin coat of fire-clay on the exterior of 
 about |th inch thick, they will not require cleaning ; this also 
 adds to their durability. 
 
THE nYDRAULIC MAIN. 
 
 129 
 
 The combination of iron and clay retorts has been very 
 extensively employed by some engineers, producing the most 
 favourable results, the average yield from Newcastle coal 
 being 9,200 feet per ton ; and in many instances in works of 
 25 millions to 100 millions a year, the fuel for carbonising does 
 not exceed 17 per cent, of the coke produced. By one of the 
 modes adopted by Mr. Anderson, 26 retorts are heated by 
 two furnaces, one of which is supplied only by a stream of 
 tar. Wherever coke is valuable and tar not marketable, this 
 plan is of great consequence, 8 gallons of tar as fuel, being 
 equal to about 1^ cwt. of coke. 
 
 CHAPTER X. 
 
 THE HYDRAULIC MAIN. 
 
 This serves the purpose of a series of valves for all the 
 retorts, and if such a contrivance did not exist, each ascen- 
 sion pipe would have to be provided with a separate valve or 
 tap, occasioning considerable labour to shut and open them, 
 every time the coke was drawn and the retort charged. In 
 addition to this, the risk and loss would be very great. But 
 ‘the hydraulic main is self-acting, beautifully simple in its 
 construction, and, with the least care, accident or loss from it 
 is almost impossible. 
 
 The hydraulic main is a tube or trunk, usually of cast 
 iron, extending the entire length of the retort ovens, and 
 varying from 12 to 20 inches diameter, and, when made of 
 cast iron, generally from f ths to f ths of an inch in thickness. 
 Wrouglit-iron hydraulic mains, however, now supersede cast 
 iron, on account of their lightness and strength. These are 
 usually made of larger diameter than the cast iron, and put 
 together in longer lengths. (See Figs. 33 to 35 for the details 
 of the wrought-iron hydraulic main erected by Messrs. 
 Cowley and Co. for the Phoenix and other gas companies.) 
 
 This is made of -|-inch boiler-plate. The cylinder forming 
 the main is composed of two circular plates and one flat piece 
 on the top, as shown in Fig. 33. The circular plates are 
 
 g 3 
 
130 
 
 THE HYDRAULIC MAIN. 
 
 made of two breadths, namely, about 3 feet and 2 feet, and 
 
 about 5 feet 6 inches in length. They break joint with each 
 
THE HYDRAULIC MAIN. 
 
 131 
 
 other, by having their line of division alternately on opposite 
 sides of the main. 
 
 The main is constructed in lengths of 23 feet, and at each 
 end of this length there is a flange 3 inches wide, shown in 
 elevation in Fig. 34, which also shows the bolt-holes through 
 which the bolts pass for securing together the separate 
 lengths of main. At the end of each length, and also mid- 
 way in each length, is a division -plate, 7 inches deep in the 
 centre, shown in Fig. 33. A plan or top view of one length 
 of main is shown in Fig. 35, which exhibits the mode in 
 which the end flange is attached to the main. This flange 
 
 consists of 3-inch angle iron, half an inch thick, bent into a 
 circular form, one side being secured to the main by f-inch 
 rivets, If inch apart all round. The bolt-holes in the face 
 of the flange, shown in Fig. 34, are f inch square. The flat 
 top plate is in lengths, of which three correspond to one 
 23-feet length of main ; each length takes seven dip-pipes. 
 Two of the openings to receive the ends of the dip-pipes are 
 shown at a a, Fig. 35. These openings are 5£ inches dia- 
 
132 
 
 THE HYDRAULIC MAIN. 
 
 meter, and 12 inches apart from centre to centre. Each open- 
 ing is surrounded by six bolt-holes, £ inch square, to receive 
 the bolts for fastening the flanges of the dip-pipes. Figs. 33 
 to 35 are drawn on a scale of T ^th, or 1 inch to a foot. The 
 cost of these mains erected complete is about £17 per ton. 
 Of course the main must be constructed for the settings 
 adopted. 
 
 Cast-iron hydraulic mains are generally of such a length 
 as to reach over one bench only, and the joints are made 
 with bolts and nuts, and cement, in the usual manner. In 
 old works the hydraulic main is often a circular tube, but of 
 late years D-shaped mains have frequently been used, with 
 the flat side upwards. 
 
 The hydraulic main when first put into action is supplied 
 about half-full with water, but in the course of operation the 
 tar contained in the gas which passes is soon deposited in the 
 hydraulic main, displacing the water, so that the sealing liquid 
 speedily becomes tar. 
 
 The end of the dip-pipe, as shown page 63, is immersed 
 to a depth of 3 or 4 inches in the liquid in the main, and 
 during the process of distillation the gas passes from the 
 retorts up the ascension-pipe, through the bridge -pipe, down 
 the dip, bubbles through the liquid into the space above, and 
 from thence to the apparatus for purification. 
 
 The action of the dip of the hydraulic main has already 
 been explained. 
 
 Each of the pipes thus dipping into the tar of the hydraulic 
 main freely delivers the gas produced in its own retort, and 
 effectually prevents its return. However numerous may be 
 the pipes dipping into the hydraulic main, whether they 
 contain gas or not, and whether the retorts are working or 
 not, it is impossible, under ordinary circumstances, that any 
 gas once arrived above the surface of tar in the main can 
 return back again, each pipe being hermetically sealed by 
 the tar. ! 
 
 The hydraulic main constitutes the first application in the 
 gas manufacture of that beautiful contrivance called the 
 water-joint. It is this contrivance which enables the chemist 
 to store and confine his gases in the receivers of the pneu- 
 
THE HYDRAULIC MAIN. 
 
 133 
 
 matic trough, and tlnis by the use of denser fluids, such as 
 water and mercury, to imprison the most volatile forms of 
 gaseous matter in a mode which, for delicacy and subtilty, 
 infinitely excels every contrivance of mere mechanical fitting. 
 We shall see hereafter how largely this valuable principle of 
 sealing up the aeriform fluids by means of denser fluids, 
 through which they can pass in one direction but not in the 
 other, has been applied in the purifier, the gas-holder, and, 
 in fact, in every one of the contrivances connected with the 
 collection, storing, and distribution of gas. At present it 
 may be sufficient to point attention to the value of this pro- 
 perty derived from the different densities of fluids, which 
 gives both to the chemist and the manufacturer a power 
 over the aeriform bodies which they would in vain strive to 
 obtain by any other means. 
 
 The length of the dip-pipe, with the part of bridge-pipe 
 to bridge, should not be less than 3 feet, and is frequently 
 made as much as 5 feet, to prevent the tar overflowing into 
 the retorts which are out of action. It is obvious that the 
 pressure of gas from the working retorts will force the tar up a 
 short distance into the dip-pipes of those retorts which are 
 not in use, but this distance is seldom equal to 3 feet. As the 
 hydraulic main is generally half-full of tar, its diameter must 
 be so regulated that the tar forced up into the dip-pipes of the 
 retorts out of action will not so far diminish the depth in the 
 main as to unseal the ends of the dip-pipes, because this 
 would simultaneously unseal every one of them, and the gas 
 would immediately escape from the main. 
 
 The hydraulic main is sometimes placed on the solid struc- 
 ture of the brick-work over the retorts, but more frequently 
 a little in advance of the ovens, in which case it requires to 
 be supported by columns. 
 
 Each length of the hydraulic main is usually provided with 
 a partition, the top of which is level with the surface of the 
 fiuid ; the object of this is to maintain that surface continually 
 at the same height in every part of the main. Of course where 
 so much depends on the effective sealing of the dip-pipes, 
 every care must be taken to fix the hydraulic main in a 
 perfectly horizontal position from end to end. When the 
 
134 
 
 VALVES. 
 
 hydraulic main is of cast iron, the holes for tlie dip-pipes often 
 are cast in it, and the flanges of the dip-pipes are secured to 
 it by nuts and bolts, the joint being made with iron cement, 
 such as used for attaching the mouth-pieces to the retorts ; or 
 a hempen or millboard washer, dipped in a mixture of white 
 and red lead, forms a tight and secure joint. 
 
 Usually one end of the hydraulic main is closed with a 
 plate fastened with bolts and nuts; a similar plate, provided 
 with an orifice corresponding in size to the exit-pipe con- 
 veying the gas to the purifiers, is attached in a like manner 
 to the other end, and on to this is bolted a flanged socket for 
 the purpose of communicating the exit-pipe thereto. Some- 
 times the two ends are closed, and the exit-pipe is attached 
 to the top of the hydraulic; in this case there is a small 
 pipe attached to the end, at the level of the surface of liquid, 
 in order to convey away the tar and ammoniacal liquor con- 
 densed. This is sealed in a similar manner to the dip-pipes 
 before described. When tar is used as fuel it can be taken 
 directly from the hydraulic main, which saves the trouble 
 of pumping, and avoids the necessity of having a reservoir. 
 When so used the tar is very fluid, but care must be taken 
 to limit the consumption, otherwise the main, being exhausted, 
 will deliver only ammoniacal liquor. 
 
 In many works where the exit-pipe is on the end of the 
 hydraulic, this is placed so to carry off the tar and ammo- 
 niacal liquor as well as the gas ; but it is always considered 
 preferable to have two distinct pipes for the purpose. 
 
 VALVES. 
 
 In addition to the hydraulic main, which as shown is a 
 series of valves for the retorts, there are two kinds of valves 
 used in gas-works, namely, the hydraulic-valve, which acts 
 on the principle of interposing a column of water in such a 
 position and of such a depth that the gas is incapable of 
 passing through it ; and the slide or surface valve, which 
 stops the flow of gas by the close contact of accurately planed 
 
VALVES. 
 
 135 
 
 metallic surfaces, the contact being preserved by the action 
 of a spring, as will presently be described. 
 
 The hydraulic -valve is chiefly used in works between 
 the gas-holders and the mains, while the slide-valves are 
 generally employed in the street mains, and are of great 
 service in stopping the flow of gas when a part of the main 
 is undergoing repair. 
 
 Figs. 36 and 37, drawn on a scale of -roth of the full size, 
 show two kinds of hydraulic-valves ; and Figs. 38 and 39, 
 
 drawn on the same scale, show the usual form of slide- 
 valve. 
 
 In Fig. 36, d is a cast-iron cylinder, usually for 12 oi- 
 li-inch mains, about 3 feet long ahd 16 or 18 inches in 
 diameter ; the other sizes being increased or diminished 
 accordingly. The top of the cylinder has a perfectly air- 
 
136 
 
 VALVES. 
 
 tight cover with a stuffing-box, through which works the 
 rod d. The gas passes into this cylinder through the pipe a; 
 the cylinder contains water or tar to the level a a, or about 
 a foot in depth. The outlet-pipe b, through which the gas 
 passes off to the mains when the communication is open, 
 lias its orifice about 3 inches above the level of the tar ; 
 ee is an inverted cup which covers the mouth of the 
 pipe b, and can be raised when required by means of a 
 pinion working into the rack on the rod d, or other suitable 
 means. It is evident when the cup is at the bottom and 
 immersed in the water, as shown in Fig. 36, the gas is her- 
 metically sealed up and prevented from entering the pipe b, 
 unless its pressure be sufficiently great to displace the water 
 and cause it to overflow into the pipe b. In this case the 
 gas would escape, but the depth of 12 inches is usually suffi- 
 cient to prevent this, and to afford a most effectual seal. On 
 the other hand, it is evident when the inverted cup e e is 
 raised above the surface of the tar, the gas will flow uninter- 
 ruptedly from the gas-holder through pipe a, and thence 
 into pipe b, which takes it off to the main. This kind of 
 valve is extremely simple and efficient, the chief objection 
 to it being that the outlet and inlet pipes are at different 
 levels, an objection 'which does not apply to the next kind of 
 hydraulic-valve. 
 
 Fig. 37 is the section of a valve which is frequently made 
 use of in works, and has the advantage of acting as a receiver 
 or syphon to contain the tar or water which drains off from 
 the gas in its passage. 
 
 The outer cylinder is about 3 feet 6 inches long, and about 
 the same diameter as the valve last described, provided as 
 before with an air-tight cover and stuffing-box, through 
 which the rod d passes : a is the inlet and b the outlet pipe, 
 both on the same level ; ee is the movable cup, not in- 
 verted in this case, but entirely immersed in water or tar 
 when at the bottom of the cylinder, and remaining full of 
 the liquid when lifted up by the rod d to close the open end 
 of the inner cylinder ; the inlet-pipe a opens into the outer 
 cylinder, and the outlet-pipe b opens from the inner cylinder. 
 The water or tar should be a little higher than the top of 
 
SLIDE-VALVES. 
 
 137 
 
 the cup, namely, as high as the line a a. On the right- 
 hand side of the engraving is a small pipe, f, with a screwed 
 top, through which the water of condensation is drawn off 
 when it reaches above the level a a. Bearing in mind that 
 the inner clylinder is open at the bottom and side, the action 
 of this valve will be readily seen. When the cup is at the 
 bottom, as in the engraving, the gas passes freely from a into 
 the outer cylinder, then up through the inner cylinder, and 
 goes off by the pipe b : when the cup e e is raised, however, 
 the lower edge of the inner cylinder rests on the bottom of the 
 cup, and being of less diameter than the cup, there is an annular 
 space of water all round, equal in depth to that of the cup ; 
 this water effectually prevents the gas from passing through 
 it and reaching the outlet-pipe. The dimensions of the 
 inlet-cylinder will depend on the diameter of the main to 
 which the valve is attached, free space being left, inside and 
 outside it, as may be readily understood. 
 
 When this kind of valve is used, where it would be incon- 
 venient to have the rod d raised by means of a pinion, the 
 cup is raised by another contrivance. The rod in this case 
 lias a thread cut on it, which works through a nut in the 
 bottom of the cup : when the rod is turned, the cup, being 
 at the same time prevented from turning, is raised by the 
 screw until it attains such a position as to seal up the bottom 
 of the inner cylinder. In small valves the rod is lifted 
 by hand. 
 
 Hydraulic-valves are now only used in gas-works, and 
 never in the streets. They have the advantage of shutting 
 off the gas very effectually, not being liable to leakage like 
 slide-valves, but have the disadvantage that an accidental 
 excess of pressure renders them useless. 
 
 SLIDE-VALVES. 
 
 Fig. 88 is a longitudinal section, and Fig. 89 a plan in 
 section, of this kind of valve, a b is the valve case ; c is a 
 circular iron disc attached to the rod e, which works through 
 a stuffing-box at the top of the valve case ; d is a spring 
 
138 
 
 SLIDE-VALVES. 
 
 which presses on the disc c, and causes it to he in perfect 
 contact with the rim of the pipe when in its place : the 
 disc is very accurately turned in the lathe, and the rim of 
 the pipe is also truly faced, as well 
 as the part a b, against which the 
 disc presses when raised so as to 
 open the communication between the 
 pipes. It is evident when the disc 
 is placed as shown in the engraving, 
 the passage of the gas is stopped, and 
 when raised by means of a pinion 
 working in a rack cast on e, the pas- 
 sage can be entirely opened. When 
 used in gas-works, the disc is worked 
 either horizontally or vertically, as 
 shown in the engraving, but when 
 employed in the street, the rod e is 
 worked horizontally, by means of a key 
 fitting the axle of the pinion ; in this 
 case Fig. 38 becomes a plan in sec- 
 tion, and the disc moves laterally 
 instead of vertically, to open the 
 communication between the pipes. 
 
 Another kind of valve has come 
 into use in gas-works during the last 
 few years : a disc similar to that 
 shown in Figs. 38 and 39 is pressed 
 by a screw upon a faced rim, and 
 when the screw is tightened, the contact is so perfect as to 
 prevent the slightest escape of gas. When the screw is 
 relieved, the disc may be raised so as to afford any required 
 opening for the flow of the gas : the screw may be placed 
 either horizontally or vertically ; and this kind of valve is, 
 perhaps, more correct and certain in its action than the 
 spring slide-valve. 
 
 Mr. Clegg describes an ingenious contrivance by Mr. Low T e 
 for intercepting the passage of gas in a main where there 
 happens to be no valve in the neighbourhood. This is 
 effected by filling up the main with a bladder distended by 
 
 Fig. 39. 
 
FURNACE DOOR, ASH-PAN, ETC. 139 
 
 common atmospheric air, the mode of proceeding being as 
 ! follows : — 
 
 . Supposing a fracture required to be repaired, or a branch 
 pipe inserted, for which purpose the main has to be cut 
 asunder or taken up for a certain length ; provide two bladders 
 each being firmly attached to a piece of i-inch composition 
 pipe about 1 foot long, and furnished with a stop-cock; then 
 drill a hole 1£ inch in diameter in the main pipe on each 
 side of the place to be operated on, and insert the empty 
 bladder into the main : which is then to be inflated through 
 the tube at the mouth, till it expands and fills up the main, 
 when the stop-cock is turned in order to confine the air! 
 rhe repairs to the pipes being finished, the air may be 
 i let out of the bladders, which can then be withdrawn, and the 
 holes in the main stopped up by screwing in an iron plug. 
 
 FURNACE DOOR, ASH-PAN, SIGHT-BOXES, AND BUCKSTAVES. 
 
 These minutiae of a setting of retorts may be described 
 briefly. At the entrance to the furnace there is a cast-iron 
 frame attached by nuts to bolts which are embedded in the 
 brick-work. This frame is usually about from 22 inches to 
 26 inches square, 1^ inch to 2 inches thick, having a rect- 
 angular opening in its centre, of about 12 inches by 10 
 inches, which is the entrance to furnace. On this frame is 
 cast a fillet for the door to repose on when shut, and two 
 pieces forming part of the hinge of the door ; the corres- 
 ponding parts of the hinge being cast with the door itself. 
 The door is about f inch thick, being larger than the opening 
 of furnace so as to allow of a lap of an inch all round : it is 
 furnished in the interior with a bevelled frame, for the pur- 
 i ? ose of receiving a fire-lump about 9 inches square, and 2± 
 inches thick, which serves to prevent the radiation, also the 
 , destruction of the door by the heat. 
 
 The ash-pan, or, as often called, evaporating pan, is a small 
 oblong tank placed immediately under the fire-bars of the 
 furnace, and, as the name signifies, serves to receive the ashes ; 
 i but its most important office is to contain water, which 
 
140 
 
 PURIFICATION OF GAS. 
 
 by the heat of the fire evaporates as steam, and, ascending, 
 plays on the fire-bars, so cooling and preserving them. 
 Afterwards the steam in its passage is decomposed by the 
 fire into its two elements, the oxygen uniting with the 
 carbon, and the hydrogen being liberated, is ‘burned ; thus 
 both the constituents of water are made available for the 
 purposes of combustion and heating the retorts. The ash- 
 pan was formerly made of cast iron, but the inconvenience 
 of this cracking has caused them now generally to be made 
 of wrought iron. 
 
 The sight-hole or box consists of small cast-iron frame 
 built into the front wall of setting, into which is fitted a plug 
 of the same material : these are circular, square, or oblong, 
 and vary in size from inches to 5 inches diameter, the 
 most common shape being 3 inches square. The use of 
 the sight-boxes is to ascertain the temperature of the interior 
 of the furnace ; they serve for cleansing the exterior of iron 
 retorts, also for removing deposit in the nostrils. 
 
 In order to prevent the brick-work being injured by 
 the expansion of the heat, it is bound by tie-bars extending 
 from side to side, and from end to end. These tie-bars 
 pass through iron supports, called buckstaves, when they are 
 screwed up tight, forming a framing for the brick-work, 
 preventing it cracking. 
 
 CHAPTER XL 
 
 ON THE PURIFICATION OF GAS. ON PURIFICATION GENERALLY. 
 
 HORIZONTAL CONDENSER. VERTICAL CONDENSER. WASH 
 
 VESSELS. SCRUBBERS. WET LIME PURIFIERS. DRY LIME 
 
 PURIFIERS. OXIDE OF IRON. 
 
 We have traced the production of gas from the retorts into the 
 hydraulic main, where, as has been shown, it is retained 
 by a beautiful contrivance, which, while freely admitting the 
 
PURIFICATION OF GAS. 
 
 141 
 
 gas to enter it from the retorts, opposes a seal hermetically 
 closed against its return into them. Thus collected in the 
 hydraulic main, the gas is capable of being burnt, and was 
 originally used in this state for the purposes of lighting, 
 without any purification. By degrees, however, it was dis- 
 covered that the numerous obnoxious matters with which 
 it was impregnated rendered it unfit for burning in private 
 houses, and one contrivance after another was adopted to 
 separate these impurities, which are referred to in the chapter 
 on the Chemistry of Gas-lighting, and are now to be more 
 fully treated on. 
 
 The process of purification is partly mechanical and partly 
 chemical ; that is to say, the tar and ammoniacal liquor are 
 separated by a mechanical process of cooling the crude gas 
 after passing from the hydraulic main, by which process the 
 vapours of tar and ammoniacal liquor in combination with 
 it are condensed and allowed to flow off into separate vessels 
 destined to receive them. 
 
 The greater part of the vapours being condensed, means 
 are then adopted to separate the tar held in suspension, also 
 the ammonia which exists as gas, and for this purpose the 
 washer or scrubber is employed. 
 
 Another means of removing the ammonia is by Mr. Croll’s 
 method of passing the gas through a weak solution of sul- 
 phuric acid or chloride of manganese, which process is very 
 effective, and gives a valuable residue. In many works the 
 ammoniacal liquor yielded by the coal is an important agent 
 in the purification of gas. 
 
 The other part of the chemical purification is by means 
 of a solution of lime or milk of lime, generally called wet 
 lime purification, or by lime slackened and moistened, called 
 dry lime purification, which absorbs the carbonic acid and 
 sulphuretted hydrogen. 
 
 Certain metallic oxides, particularly the oxide of iron, are 
 also much employed for removing the sulphur compounds; 
 and the Rev. Mr. Bowditch has devoted himself to the puri- 
 fication of gas from that troublesome impurity, bisulphide of 
 carbon, by passing the gas to be purified through a chamber 
 filled with lime heated to about 400° Fahr. These and other 
 
THE CONDENSER. 
 
 142 
 
 processes will be treated on in future pages. The impurities 
 being separated, the gas is suitable for the ordinary purposes 
 of lighting, and accordingly passes to the holders, to be stored 
 for use. 
 
 THE CONDENSER. 
 
 There are two forms of condensers in use, the horizontal 
 and vertical. The horizontal condenser is a rectangular box 
 or chest formed of cast- iron plates, put together with flanges, 
 and perfectly tight joints. Its interior is provided with a 
 series of iron trays, containing each about 2 inches in depth 
 of water, and so arranged that the gas, entering at the 
 bottom of the chest, passes in succession over the surface of 
 the water in each tray, and traversing the whole length of 
 trough ten or twelve times, passes off at the upper side. In 
 the mean time a continuous stream of water enters at the 
 top, and in its descent absorbs a portion of the ammonia, at 
 the same time cooling and condensing the vapours in com- 
 bination with the gas. This condenser was invented by Mr. 
 Malam, and was formerly very generally used, but is now 
 superseded by the surface or air-condenser and scrubber. 
 
 Horizontal condensers are sometimes composed of a series 
 of pipes placed in a horizontal position, and immersed in 
 water. 
 
 The other form of condenser, which is very generally 
 employed, consists of a series of vertical pipes, connected in 
 pairs by semicircular bends at the top, and attached to a cast- 
 iron box or chest at the bottom. This chest has a series of 
 divisions, the ends of which are sealed by liquid placed 
 therein, so that the gas in its passage has to pass through 
 the whole series of pipes. The pipes by their contact with 
 the atmosphere radiate the heat acquired from the gas in 
 its passage, and it being in consequence cooled, deposits 
 the vapours as liquid in the form of tar, and water satu- 
 rated with ammonia, generally called ammoniacal liquor. 
 This condenser is sometimes used with an application of cold 
 water on its exterior, in order to increase the cooling effect. 
 
 Fig. 40 shows a longitudinal section, and Fig. 41 a cross 
 section of a vertical air-condenser, with the air-pipes attached 
 
THE CONDENSER. 
 
 143 
 
 to the iron chest, which is filled with water to the line a a . 
 The longitudinal section shows that the chest is divided trans- 
 versely into compartments, each of which contains two pipes 
 communicating freely with each other, the gas passing from 
 
 one to the other over the surface of the water, and being 
 prevented by the water from going in the opposite direction. 
 The cross section shows that the chest is divided longitu- 
 
144. 
 
 THE CONDENSER. 
 
 dinally into two compartments, each of which receives one 
 row of pipes. 
 
 In Fig. 41 the gas entering into the compartment below 
 the pipe b, passes up that and down pipe c, in the direction 
 of the arrows, into the next compartment, from whence it 
 passes into another pipe, as seen in Fig. 40. So that it has 
 to traverse the whole length of the pipes, which radiate the 
 heat communicated to them by the gas in its passage. 
 
 Another form of air-condenser has lately become very 
 general in large works, and consists of an iron chest similar 
 to that described, but of much greater dimensions, surmounted 
 by a series of vertical pipes of great diameter, in which are 
 enclosed others considerably smaller, the two forming an 
 annular space. Through this annular space the gas to be 
 condensed passes, and the interior of the inner cylinder being 
 open to the atmosphere allows a current of air to enter 
 below, which becoming heated, ascends, causing a draught or 
 current ; hence the superiority of this system. There are 
 external pipes which communicate the various condensing 
 columns with each other, and so complete the apparatus. 
 The condenser used at the Imperial Gas Works of London 
 consists of ten upright pipes, each 3 feet 6 inches diameter, 
 and 22 feet high, having pipes 24 inches diameter to com- 
 municate between the condensing columns. In some works 
 the condenser is replaced, by the pipes from the hydraulic 
 main to the purifiers being attached to the walls of the 
 buildings and exposed to the atmosphere, when a considerable 
 length of pipe is of course requisite. 
 
 The researches of Peclet and other French writers on 
 Physics, demonstrate that a far greater extent of cooling 
 surface is required when radiation takes place in air than 
 when the same takes place in water, as when the condensing 
 pipes are in that medium. 
 
 It appears, wnere the gas has an excess of temperature of 
 10 degrees over the atmosphere, that a unit of surface which 
 would radiate 8 parts of heat in the open air, would in water 
 radiate no less than 88 parts of heat ; and the following table 
 expresses the proportionate radiation in the two cases for an 
 excess of temperature up to 50°. 
 
TTTE CONDENSER. 
 
 145 
 
 Excess of temperature 
 in the gas. 
 
 Quantity of heat lost 
 by a square unit of the exterior | 
 surface of pipe. 
 
 When radiating 
 in open air. 
 
 When plunged 
 into water. 
 
 For an excess of 10° 
 
 8 
 
 88 
 
 „ „ 20 
 
 18 
 
 266 
 
 „ „ 30 
 
 29 
 
 5353 
 
 >> ft 40 
 
 40 
 
 8944 
 
 ft ft 50 
 
 53 
 
 13437 
 
 In examining this table we find a vast difference in the 
 quantity of heat absorbed by water, especially as the excess 
 of temperature rises ; and hence it follows that if the system 
 of condensation by simple radiation into the air be adopted, 
 the extent of surface exposed must be much greater than 
 when water is used ; but although this would show a supe- 
 riority of water as a cooling or condensing medium, yet it is 
 generally believed that there is a certain mechanical effect 
 produced in the gas passing through the series of pipes, 
 which assists materially in the purification. This may be the 
 reason why the air-condenser is so generally used almost to 
 the exclusion of the other. Formerly water-condensers were 
 much employed, now they are seldom seen, practice having 
 proved theory to be incorrect. 
 
 The gas in passing the condenser is acted on mechanically, 
 by its various particles coming into contact with the surface 
 of the pipes, and by this friction a large portion of the tar is 
 deposited. The same effect will be observed with the purifi- 
 cation ; when the exhauster is used the friction assists in the 
 deposit of the tar. 
 
 But gas may be condensed to an excess ; when this occurs 
 naphthaline is deposited in the mains and services, causing 
 continual annoyance, which is particularly the case in winter, 
 when the condensation should be limited. 
 
 Where the system of cooling by radiation in air is adopted, 
 it is very advisable in dry and warm weather to assist the 
 
 n 
 
146 
 
 THE CONDENSER. 
 
 cooling by allowing small streams of water to trickle down 
 on the outside of the condensing pipes : this is effected by 
 having a cistern of water fixed over them. The cooling 
 effect of this water evaporating on the outside of the pipes is 
 greater than if the latter were placed in w r ater, owing to the 
 great quantity of caloric which passes from a sensible to a 
 latent state during the formation of vapour. The more 
 rapidly the vapour is formed, the greater will be the cooling 
 effect, from which it follows that the effect will be greatest 
 when the sun shines most powerfully, and that the con- 
 denser should always be exposed as much as possible to the 
 direct rays of the sun. 
 
 The evidence taken in 1849 and 1850 before the Parlia- 
 mentary Committees which sat on the Great Central Gas Con- 
 sumers’ Bill, affords some valuable information on the subject 
 of prices and the general construction of large works. The 
 project brought forward by Mr. Croll, the engineer of the 
 Company, contemplated an annual production of 368,000,000 
 cubic feet of gas, and the estimate for condensers in a gas- 
 work of this magnitude was £1,237, exclusive of a concrete 
 foundation, which would cost £5 or £6 more. 
 
 Mr. Barlow, in his Report to the Directors of the City of 
 London Gas Company, made no objection to this amount, 
 and adopted it in his own calculation. This estimate is equal 
 to *807<L per 1,000 feet of gas per annum, or £1’23 per 1,000 
 feet of average daily production. Mr. Croll proposed to use 
 for these condensers 128 pipes, each 9 feet in length and 18 
 inches in diameter ; to have a box at top and bottom of each 
 condenser divided into partitions, so that the gas should 
 pass alternately up one pipe and down another in the usual 
 manner. 
 
 The entire length of condensing pipe being 1,152 running 
 feet or -5,472 feet surface, if we add 828 feet for the surface 
 of top and bottom boxes, we have 6,300 feet condensing area, 
 or about 4 feet superficial per 1,000 feet maximum production 
 per diem. 
 
 These condensers have amply realised all that was an- 
 ticipated, as upwards of two millions of feet have frequently 
 been condensed by them in the twenty -four hours. 
 
ON THE TAR AND AMMONIACAL LIQUOR-TANK 147 
 
 ON THE TAR AND AMMONIACAL LIQUOR-TANK. 
 
 The tar and ammoniacal liquor, as condensed, flow from 
 the hydraulic main and condenser to a vessel called the tar- 
 tank. This is sometimes built in the ground in masonry, 
 when it requires to be constructed with all the precautions 
 employed in building the tank of a gas-holder. Or it is 
 formed of cast-iron plates, bolted and cemented together ; 
 or it may be made of boiler-plates riveted, to form either a 
 rectangular or circular vessel. In all cases it is desirable that 
 the tar-tank should be covered over to avoid the evaporation 
 and odour which would issue from it ; also to prevent the dust 
 and dirt entering and intermixing with the tar. 
 
 Whatever kind of condenser be adopted, it is necessary to 
 make provision to hinder the escape of gas through the same 
 pipe which carries the ta]r and ammoniacal liquor into the 
 tank. The mode of effecting this is shown in Fig. 42, 
 where abcd represent the tank, and k l the pipe open at 
 
 K 
 
 the lower end, through which the products of condensation 
 enter, e f g h is a cylinder of larger diameter than k l, open 
 at the top and resting at the bottom on the base of the tank, 
 and filled with water nearly to the top. It is evident that the 
 tar and ammoniacal liquor discharged at l will accumulate in 
 the cylinder, and afterwards flow over into the tank at the 
 H 2 
 
148 ON THE TAR AND AMMONIACAL LIQUOR-TANK. 
 
 top, e H, while the pipe dipping into the water forms an 
 effectual seal against the emission of any gas. 
 
 Where an upright condenser is used, consisting of iron 
 pipes connected at the bottom by circular pipes, instead of 
 having the chest described, a modification of the last method 
 is used as follows : — A cylinder, represented by efgh, is 
 placed under each of the circular bends, with a pipe, k l, 
 leading into it. Immediately above the level of the water in 
 e h, branches off a pipe secured to the cylinder by a flange 
 and leading into the tar-tank, which runs the whole length of 
 the range of condensing pipes, and the products of conden- 
 sation flow off through this into the tar -tank. 
 
 This mode of sealing various parts of the apparatus is very 
 common in gas-works ; often a small vessel of this descrip- 
 tion is placed at the end of the hydraulic main, or at the ends 
 of the air-condenser, so that in the event of a stoppage in 
 the pipes on the works, either through the syphons not being 
 pumped, or other causes, these seals give notice of it by the 
 gas blowing off from there, acting, indeed, as a kind of safety- 
 valve, and preventing any extraordinary excess of pressure. 
 
 The capacity of a tar-tank must depend on the magnitude 
 of the works, and the facilities afforded in disposing of the 
 residues. Mr. Peckstone gives the capacity of a tank for a 
 works carbonising about o tons a day in mid-winter, at 
 540 cubic feet, which is rather more than 100 cubic feet for 
 each ton of coal carbonised daily. In estimating the size of 
 the tar-tank it is usual to calculate that each ton of coal 
 produces from 100 to 140 lbs. of tar, and from 10 to 13 
 gallons of ammoniacal liquor in most instances, and it is 
 proper to have the tank large enough to hold about six 
 weeks* production of the liquids. This agrees very nearly 
 with the estimate just mentioned. 
 
 In the tank both the tar and ammoniacal liquor are con- 
 tained; however, they do not mix together, because the 
 ammoniacal liquor being considerably lighter than the other, 
 floats on the top, the tar being at the bottom. When either 
 of these liquids may be required it is drawn out by means of 
 a pump, with movable suction -hose, which can be adjusted 
 so as to have its orifice either in the ammoniacal liquor or in 
 
ON TIIE WASH-VESSEL. 
 
 149 
 
 the lighter or heavier portion of the tar, by which contrivance 
 either liquid can be pumped out as desired. 
 
 At most gas-works both the tar and ammoniacal liquor 
 are sold, the price for tar varying from Id. to 1 \d. per 
 gallon ; the ammoniacal liquor is generally sold by contract 
 per annum. At many large and medium size works this is 
 manufactured on the premises into a commercial commodity; 
 usually, on account of the simplicity of the operation, into the 
 sulphate of ammonia. 
 
 ON THE WASH-VESSEL. 
 
 Figs. 43 to 45, drawn on a scale of 1 inch = 3 feet, show 
 the details of a washer as used in some works between the 
 
 ___0 , 
 
 Fig. 43. 
 
 condenser and purifiers. Fig. 43 is a plan looking down 
 upon the washer; Fig. 44 is a side elevation, and Fig. 45 a 
 
150 
 
 ON THE WASH-VESSEL. 
 
 front elevation. In Fig. 43 a b c d is tlie iron vessel termed 
 the washer ; it is made of boiler-plates securely riveted toge- 
 ther. In Fig. 45 is seen the front elevation of this vessel, which 
 in the engravings is represented about 5 feet wide and 4 feet 
 deep at the ends; the depth in the middle does not exceed 18 
 inches, as more particularly shown by the outline in Fig. 44. 
 The lower part of the vessel is filled with water to the level 
 g h in Fig. 44. The pipes communicating with the con- 
 denser, and those by which the gas passes off from the wash- 
 vessel, are all marked with corresponding letters of reference 
 
 m the three figures, and by the aid of these I shall now trace 
 the progress of the gas. Passing from the hydraulic main 
 (see Fig. 45), the gas ascends the pipe a, and proceeds along 
 pipe b. If intended to be passed into the right-hand extre- 
 mity of the washer, the valve l is kept open, and the gas 
 passes down the pipe d, and enters the space m. Out of this 
 space it has no means of escape, except by displacing the 
 water and passing up at the other extremity of the vessel 
 
ON THE WASH-VESSEL. 
 
 151 
 
 into the space n. Arrived here, it passes up the pipe e, and 
 finally goes on through f. If it be intended to pass the gas 
 
152 ON TIIE SCRUBBER, OR COKE CONDENSER. 
 
 through the wash -vessel in a contrary direction, the valve l 
 is closed, and the gas then goes from pipe b into c, and 
 descends through the pipe e into n, the left-hand extremity 
 of the washer : it then passes through the water as before, 
 escapes into m, and goes off through pipe f as in the other 
 case. The valves j k l, the use of which will be readily 
 understood from an inspection of the engravings, are marked 
 with corresponding letters of reference in each of the three 
 figures. 
 
 This description of washer was very generally employed 
 some years ago, but it was ascertained that, by washing the 
 gas, a large portion of the hydrocarbons were deposited 
 during the operation, and, in consequence, the illuminating 
 power of the gas was diminished, a circumstance which 
 caused the wash-vessel to be superseded by the scrubber. 
 
 ON THE SCRUBBER, OR COKE CONDENSER. 
 
 This apparatus has now become very commonly employed 
 for the purpose of separating the ammonia from the gas ; it 
 also takes up the tar that may have passed over from the 
 air-condenser. 
 
 The scrubber is generally a cylindrical cast-iron vessel, its 
 height being from two to four times its diameter, those of 
 large diameter being proportionally short. This vessel is pro- 
 vided with suitable man-holes for the purpose of discharging 
 and charging the apparatus with coke or other porous materia], 
 the inlet pipe being at the bottom, the outlet at the top. 
 
 In the interior there are two, three, or more flanges for 
 the purpose of supporting the necessary perforated plates, or 
 shelves. On these is generally placed coke so to fill the 
 scrubber, which done the man -holes are closed hermetically. 
 Beneath the lowest shelf there is a chamber for the pur- 
 pose of receiving any breeze that may be carried there by 
 the water, and the inlet opens into this chamber. A supply 
 of water is caused to enter the centre of the vessel at top, 
 which, in its descent, trickles over the whole mass of coke, 
 and comes in contact with the ascending gas, which yields 
 its ammonia to the water, and the tar is mechanically 
 
PURIFICATION BY WET LIME. 
 
 153 
 
 retained by the coke. Sometimes this vessel is used in the 
 dry state, the coke in that case only abstracting the tar from 
 the gas. 
 
 The modern plan generally adopted at large establishments 
 is to have several of these vessels, and the ammoniacal liquor 
 produced by the condensation of the vapours from the distil- 
 lation of coal flows into a cistern, from whence it is pumped 
 into the scrubbers ; and by this repeated operation the 
 ammonia is abstracted from the gas, and the liquid becomes 
 a commercial and valuable commodity. The ammoniacal 
 liquor, as delivered from the air-condenser, possesses little 
 value, on account of the small quantity of ammonia therein ; 
 but, when treated as stated, it not only becomes an important 
 purifying agent, but is itself much increased in value. 
 Another advantage of the process is that the hydrocarbons 
 are not deposited by the operation as when pure water is 
 employed. These scrubbers require periodical cleansing ; 
 otherwise the tar and coke would form a compact mass, and 
 so prevent the passage of the gas ; this being shut off by 
 proper by-pass valves, the coke is withdrawn from the man- 
 holes and fresh coke replaced. Cleansing once in three or 
 four months is generally sufficient. 
 
 PURIFICATION BY WET LIME. 
 
 By the combined action of the condenser and scrubber, the 
 gas is deprived of the ammonia and the tar which existed there- 
 with ; there still, however, remains sulphuretted hydrogen 
 carbonic acid, with other impurities ; and for the complete 
 removal of the two named, probably wet lime or the cream 
 of lime is superior to all other means of purification. 
 
 In this process, the lime, after being slacked, is mixed with 
 water in the proportion of about 18 gallons of the latter to 
 two bushels of slacked lime. It is necessary to mix the lime 
 and water together in a separate vessel, because the pre- 
 pared lime must be introduced to the purifier in a fluid state. 
 Hence the mixing is commonly effected in a large brick or 
 iron cistern placed at a higher level than the purifiers. In 
 ihe centre of the cistern is fixed an iron shaft, carrying at its 
 
154 
 
 PURIFICATION BY WET LIME. 
 
 lower end a stirrer or agitator (something like the contri- 
 vance used in the mash -tubs of the great breweries), which 
 is caused to revolve by manual labour or steam-power. By 
 means of this stirrer the lime and water are kept in a state 
 of agitation, — the lime being mechanically suspended in the 
 water, when it is allowed to flow into one of the purifiers, 
 having suitable agitators to keep it in a state of solution, 
 otherwise the lime would speedily be deposited, as the water 
 does not chemically combine with or dissolve it. 
 
 In large works often two or three sets of purifiers are 
 used, each set consisting of two purifiers. When economy 
 of space is an object, they are sometimes placed one above 
 the other ; at other times are placed side by side. They 
 should always, however, be at different levels, as in working 
 them it is usual to cause the contents of the higher purifier 
 to flow into the other, from whence the impure cream of 
 lime is withdrawn. The fresh lime is always admitted into 
 the upper purifier, the crude gas entering the lower, where it 
 becomes partially purified ; from thence it passes to the other, 
 and the process is completed. The revolution of the stirrer 
 of the purifiers is effected by the steam-engine (now used in 
 most gas-works), a bevelled wheel on the upright shaft gear- 
 ing into a similar wheel on a horizontal shaft driven by the 
 engine. 
 
 The wet-lime purifier consists of a cast-iron cylinder en- 
 tirely closed at top and bottom, except where the inlet and 
 outlet pipes join it, and where an opening is required for 
 charging it with lime-water, which same opening is also used 
 for drawing off the charge. To the inside of the cover of 
 this outer cylinder is bolted an inlet cylinder usually made of 
 wrought-iron plate. This inlet cylinder is open at the lower 
 part, and reaches to within a foot from the bottom of the outer 
 cylinder, but has bolted to its lower flange a wide ring or dash 
 plate of sheet iron, the outer diameter being only 8 or 9 inches 
 less than that of the outer cylinder, so that a space of about 4 or 
 5 inches is left between the outside of the ring and the interior 
 of the large cylinder. These particulars will be more fully 
 understood from the woodcut, Fig. 46, to which reference is 
 now made, a is the outer cylinder and b the inlet cylinder, 
 
PURIFICATION BY WET LIME. 
 
 155 
 
 into which the pipe c opens to admit the gas from the con- 
 denser, or scrubber. The gas passes down through the inlet 
 cylinder b, and by its pressure forces its way up through the 
 fluid lime, the surface of which, d d, is 8 or 9 inches above 
 the dash plate attached to b: e is a hoop of angle-iron attached 
 by bolts to the inside of the purifier, of such a diameter as to 
 allow only half an inch of space to intervene between it and 
 the iron dash plate attached to b. The bottom of the angle - 
 iron hoop is on a level with the dash plate, so that the gas 
 has to find its way through the small space between them : f 
 
 is the revolving arm or stirrer keyed on to the shaft b , which 
 works in a bearing fixed on the bottom of the purifier, and 
 passes through a stuffing-box in the lid, being worked by a 
 bevel-wheel, as already described for the mixing vessel. To 
 the main arm is attached a band of bent wrought-iron, h h, 
 which continues up through the small opening already spoken 
 of, and laps over the dash plate till it nearly touches the inlet 
 cylinder, the object of this being to keep up the agitation and 
 prevent the solid particles of the lime from settling ; it also 
 keeps the half-inch opening clear and free for the gas to pass 
 through, k is the outlet-pipe for the purified gas after it has 
 
156 
 
 DRY- LIME PURIFICATION. 
 
 passed through the solution of lime, and readied the annular 
 space between the outer and inner cylinders, l is an outside 
 chamber, and m an outlet-pipe connected with the purifier 
 by a siphon-pipe n ; the pipe m is provided with a valve, 
 which is kept closed, except when the contents of the purifier 
 are to be drawn off. The lime-water is conveyed into the 
 purifier through the chamber l, and when it is required to 
 empty the purifier, the valve in m is opened. As the siphon- 
 pipe n must always remain filled with fluid, it is evident that 
 no gas can escape when the lime and water are drawn off*. 
 This arrangement is necessary, as when wet-lime purifiers 
 were first used, a serious explosion occurred from the escape 
 of gas along with the spent material. The wet-lime purifiers 
 are variously worked ; when four are used, two vessels are 
 employed at one time, and when the lime in the first is 
 incapable of absorbing the impurity, that purifier is put out 
 of action, and the second and third are worked, and so on in 
 succession. 
 
 The general impression is that wet-lime purification is the 
 most perfect mode for the effectual removal of carbonic acid 
 and sulphuretted hydrogen. But the operation of discharging 
 the apparatus, together with the residues of the process, are 
 so very offensive to the surrounding vicinity, as to prevent 
 this means of purifying being applied except in instances 
 where the works are quite isolated ; and even then the diffi- 
 culty arises how T to dispose of the waste lime. The stench 
 from this is so intolerable as to prevent it being deposited 
 with ordinary rubbish ; and I believe no practical method 
 has been adopted of commercially applying it, being used only 
 as luting for the retort doors. Therefore, wet-lime purification 
 is seldom adopted at works established in towns or cities. 
 
 DRY-LIME PURIFICATION. 
 
 When quick lime is slackened, reduced to powder, and 
 slightly moistened with water, it is called by chemists the 
 hydrate of lime, and is often employed to absorb the sulphu- 
 retted hydrogen and carbonic acid from the gas. The process 
 is termed, rather inappropriately, dry-lime purification. 
 
 The advantages ensured by this system are, — avoiding 
 
DRY-LIME PURIFICATION. 
 
 157 
 
 the heavy pressure on the retorts, which always exists when 
 wet-liine purifiers are used, in consequence of the gas having 
 to force a passage through a column of w r ater. The residue 
 of dry -lime purification is readily disposed of, being avail- 
 able for agricultural purposes, much used in the formation of 
 compost heaps, and occasionally employed in top dressing ; 
 it is also useful as a foundation or substratum for gravel 
 pathways, as it prevents the worms from coming up and dis- 
 figuring the walks by heaping up those little spiral coils of 
 earth so distasteful to the gardener. In dry -lime purification 
 no motive pow T er is required, and the odour arising from the 
 residue is not so obnoxious as that from wet-lime purification. 
 These are advantages which have caused this process gene- 
 rally to supersede the other. 
 
 The vessels in which the operation is conducted are called 
 purifiers, and consist of two or more vessels acting in con- 
 junction with each other, charged with the hydrate of lime, 
 the gas passing through one or several of these until properly 
 purified. 
 
 Dry-lime purifiers are generally rectangular cast-iron 
 vessels, varying from 3 feet to 30 feet square, and from 
 3 feet to 4 feet 6 inches deep. Sometimes in small w T orks 
 they are made circular ; this, however, is not very frequent, 
 and is done for convenience or economy in construction. 
 Each purifier contains a series of perforated shelves, trays, or 
 sieves, supported by suitable bearers of wrought or cast iron, 
 the ends of which are attached to “snuggs” cast on the 
 purifier. In large purifiers there are also pillars placed at 
 intermediate distances to carry the weight of the sieves and 
 purifying material. 
 
 The upper part of the purifier is surrounded by a cistern 
 or reservoir of from 6 inches to 24 inches deep, and from 
 3 inches to 6 inches wide, which is often cast with the puri- 
 fier and forms part of it, or at other times is attached thereto 
 by bolts and cement, and is for the purpose of containing 
 water to seal the cover. The cover of the purifier is of 
 boiler plate or cast iron, the latter being preferable on account 
 of its durability; but the increased weight is an impediment to 
 its adoption. The rim or border of the cover is rather deeper 
 
158 
 
 DRY-LIME PURIFICATION. 
 
 than the cistern into which it is placed, and is effectually sealed 
 by the water, so preventing the gas escaping from that point. 
 
 Often, the purifier is divided into two compartments, so 
 that the gas ascends through a set of sieves on the one side, 
 and descends through another set on the other side, answering 
 the purpose of two vessels. In all establishments, however 
 small they may be, two distinct purifiers at least are neces- 
 sary, to enable the impure lime to be removed from the one 
 whilst the gas is being purified by the other. 
 
 The number of purifiers in a work is variable ; in the 
 majority of establishments, a set of four is very usual, their 
 dimensions being determined by the capacity of the works — 
 the general calculation when dry lime alone is used being 
 to allow one superficial yard of sieve for every thousand 
 feet of gas produced per diem. Thus, a works producing 50 
 millions per annum (or a maximum of 220,000 per day) will 
 require four purifiers, each 9 feet square, having six sieves 
 each. 
 
 Formerly, the means of changing the passage of the gas 
 to and from the various purifiers, and shutting it off from 
 those vessels, was accomplished by a series of slide-valves 
 attached to the pipes. This plan was exceedingly costly, and 
 was attended with much serious inconvenience. The remedy 
 for this was supplied by Mr. John Malam, whose name 
 is intimately identified with the progress of gas-lighting, and 
 more particularly in connection with the gas-meter. To that 
 gentleman we are indebted for the beautiful modification of 
 the hydraulic valve, by which the gas is received at its first 
 entry into the purifying machinery, made to traverse all the 
 various vessels and pipes in succession, and is at last dis- 
 charged from thence in almost a pure state, to be stored up 
 in the holder. 
 
 The hydraulic valve consists of a cast-iron tank, the 
 diameter and height of which depends on the number and 
 size of pipes connected with the purifiers. 
 
 For a set of four purifiers, each being 12 feet square, with 
 12-inch connection pipes, the tank is about 4 feet 6 inches 
 in diameter, and 3 feet 6 inches deep. In the bottom there 
 are nine holes perforated to permit the pipes to pass freely, 
 
DRY-LIME PURIFICATION. 
 
 159 
 
 and these are attached to the tank by flanges and bolts in 
 the usual manner. The tank has a cover, through which 
 passes a rod working in a stuffing-box, for the purpose of 
 lifting the vessel which regulates the direction of the gas. 
 
 Fig. 48 represents a plan of a set of purifiers with 
 hydraulic valve, as constructed by Mr. Walter Mabon, of 
 Manchester, a b c d are the four purifiers (for want of space 
 only part of c and d are shown). The purifiers A and c are 
 inclosed by the covers ; those indicated b and d are open, 
 showing the mode of construction and half of the sieves 
 placed ready for receiving the lime, e is the central 
 hydraulic valve, in which meet the various pipes conveying 
 the gas to and from the purifiers ; as also the inlet pipe a 
 and outlet o. The pipes marked 13 5 and 7 are the inlet 
 pipes, which convey the gas from the central valve to the 
 respective purifiers ; the pipes parked 2 1 6 and 8, convey 
 the gas from the purifiers to the valve. 
 
 The vertical pipes in the tank of the valve e are about 18 
 inches long ; and, when in operation, the tank is filled with 
 water to the level of the top of these pipes. In the tank 
 there is a cylindrical vessel, closed at the top, and divided, 
 to within 4 inches of the bottom, into five vertical compart- 
 ments — a bed and e, see Fig. 49. This vessel incloses the 
 nine pipes in such a manner that the inlet and outlet pipes 
 of two separate purifiers are inclosed respectively in the 
 compartments bed. That marked a connects the central 
 pipe with the inlet of the first purifier, and the compartment 
 d contains the outlet only of the last purifier. 
 
 I now propose to trace the progress of the gas from its 
 entrance to its exit to the gas-holder. The tank having 
 been supplied with water, the gas flows by the centre pipe 
 under the cylindrical vessel into the compartment a. As 
 it has no means of escape, except by passing down the pipe 1, 
 which leads to the purifier c, it ascends through the layers 
 of lime, and passes down pipe 2 to the cylindrical vessel 
 into the compartment b. Here also it can only escape by 
 the pipe 3, and through the lime of purifier a in the direction 
 of the arrows back to compartment c, from thence into puri- 
 fier b, and after traversing the layers of lime, again returns 
 
ICO 
 
 DRY-LIME PURIFICATION. 
 
 Fig. 47 
 
DRY-LIME PURIFICATION. 
 
162 
 
 DRY-LIME PURIFICATION. 
 
 to compartment d , where there is an opening in the top of 
 the cylinder, through which the gas escapes to the holder by 
 the orifice o in side of tank. The compartment e contains 
 the inlet and outlet of the purifier d, so that the gas cannot 
 enter therein, and, being out of action, affords the facility of 
 changing the lime. 
 
 It will be observed that by this means only three purifiers 
 are in operation, the fourth in the meantime having the foul 
 lime removed and fresh supplied. In order to change the 
 passage of the gas, the cylinder is then raised by the handle 
 of the rod which passes through the stuffing-box until the 
 partitions clear the pipes. It is then turned a fourth of a 
 circle, and allowed to descend into its seat, when the gas first 
 enters the purifier a, from there to b and d, whilst purifier c is 
 thrown out of action for the purpose of changing the lime. By 
 these simple and ingenious means the passage of the gas to 
 and from the purifiers is regulated with the greatest facility. 
 
 Fig. 47 represents two of the purifiers just described, 
 — the one in elevation, the other with the front plate 
 removed to show the interior, and a section of the hydraulic 
 valve. There are four sieves for the lime, through which 
 the gas traverses, and, when above the top layer, descends 
 the pipe, as indicated by arrows. The covers of purifiers are 
 strongly stayed, and are lifted by means of a screw or crane. 
 Under the central valve there is a tank, in which stand the 
 pipes ; these are open at the bottom ; the tank being filled 
 with water prevents the gas escaping. This system has the 
 advantage that no syphons are required to be attended to, and 
 any condensation that may take place in the pipes flows into 
 the tank. The divisions of the cylinder inside the valve are 
 shown in Fig. 49, with the outlet orifice in compartment d. 
 
 This principle of hydraulic valves is also applicable where 
 there are only two or three purifiers. There is a modifica- 
 tion of it manufactured as a slide ; and if these are made in a 
 perfect manner they are superior to the hydraulic, inasmuch 
 as when required they can be shifted in an instant, so that 
 no unpurified gas passes, which circumstance always occurs 
 with the hydraulic valve when lifted incidental to changing 
 the position. 
 
DRY-LIME PURIFICATION. 
 
 163 
 
 On the tops of the purifier covers there should always be 
 valves, or stop-cocks of large dimensions, so as to admit air 
 into the purifier when in the act of raising the covers. Also 
 very small taps with a single jet attached, destined for trying 
 the purity of the gas by means of tests. When the gas is 
 changed from one set of purifiers to the other, the cover of 
 that purifier requiring fresh lime is removed, the waste lime 
 discharged wheeled away, and fresh lime substituted. A 
 very common impression exists, that the lime to be effective 
 should be carefully sifted and reduced to a fine powder; this 
 is erroneous, all that is requisite is to well slacken it ; and 
 this done, it should always be moistened to that degree that 
 when pressed in the hand it adheres together in a mass ; 
 but if too much wetted it is likely to obstruct the passage 
 of the gas, which should be avoided. A layer of about 
 2 or inches thick on the sieves is the most effective. 
 
 On the quality of the lime used will depend the quantity 
 required to purify a given quantity of any particular gas. 
 
 Mr. Clegg has fallen into an error in speaking of the 
 qualities of lime best adapted for purification. He rightly 
 
164 
 
 DRY-LIME PURIFICATION. 
 
 gives the preference to that made from the purest limestones, 
 and then observes that the purest lime is obtained from the 
 lias limestones and the lower oolite. Now this is contrary to 
 all received experience, and analysis always shows that the 
 lias limestones, both the white and blue varieties, contain a 
 large per-centage both of alumina and silex. Many of the 
 lias limestones contain as high a per-centage of these foreign 
 ingredients as the septaria, or cement stones, and are, like the 
 septaria, mere argillaceous carbonates of lime. It is, in fact, 
 this union of clay and lime in the same stone which gives to 
 the lias lime its peculiar and valuable hydraulic properties of 
 setting under water, and of setting under all circumstances 
 much more rapidly than the fat or pure limes. The same 
 remarks as to impurity apply in some degree to the lower 
 oolitic limestones, which are all more or less impure, and not 
 nearly so well fitted for the purification of coal gas as the 
 weak chalk limes. I venture to submit the following classi- 
 fication of the best-known limestones of this country, in the 
 order of their purity, and which order also expresses their 
 value for the purpose of purifying gas. 
 
 1. The white chalk limestone of Merstham, Dorking, 
 Charlton, Erith, and other parts of the chalk range surround- 
 ing the metropolis. 
 
 2. The grey chalk limestone, from the lower beds of chalk 
 
 3. The blue beds of the upper and middle oolites. 
 
 4. The lower, white, and grey limestones of the oolites. 
 
 5. The most calcareous and crystalline beds of the car- 
 boniferous or mountain limestone, colours grey and bluish. 
 
 6. The magnesian limestone of Yorkshire and Derbyshire. 
 
 7. The white lias limestone. 
 
 8. The blue lias limestone. 
 
 9. The Silurian limestones of Wenlock, Dudley, &c., and 
 the coralline limestones of Plymouth and the neighbourhood. 
 
 In passing the gas through a succession of either wet or dry 
 lime purifiers, it is important to be able to test the quality of 
 the gas at each stage of the manufacture, in order to deter- 
 mine whether the purifiers are acting properly, to afford a 
 check on the quality of the coal used, and to determine whether 
 it is necessary to turn off one of the purifiers and bring 
 
DRY-LIME PURIFICATION. 
 
 165 
 
 another into work with a charge of fresh lime. The most 
 delicate test for sulphuretted hydrogen is a solution of nitrate 
 of silver in distilled water, made by adding 4 grains of nitrate 
 of silver to 2 ounces of distilled water. The test, however, 
 most commonly used is acetate of lead, made by adding to 
 distilled water as much acetate of lead as it will dissolve. 
 The solution so made may be spread over the surface of a 
 piece of writing-paper with a camel-hair pencil ; and when 
 paper so prepared is applied, while the solution is still wet, 
 to a small stream of gas, the shade of colour produced 
 indicates the degree of impurity of the gas. In all works 
 the purifiers should be provided with a stop-cock and a very 
 small single jet burner, so that on turning the stop-cock a 
 minute stream of gas will issue, sufficient to show its quality 
 by the application of the test-paper. The pipe leading into 
 the first purifier is furnished with a similar stop -cock, from 
 which the crude gas issues, when required, before purifica- 
 tion. If the test paper be held for a few seconds in front of 
 the small stream of gas containing sulphuretted hydrogen, 
 the paper will be instantly blackened, owing to the union of 
 sulphur with lead, and the consequent formation of proto- 
 sulphide of lead, which is characterised by its black or 
 brownish-black colour. The test varies according to the 
 quantity of sulphide deposited. On applying a fresh surface 
 of the test-paper to the gas from the first purifier, the dark 
 shade is not so intense, as there is less sulphur to combine 
 with the lead, and consequently less of the sulphide is formed. 
 The gas from the second purifier ought to give only a slight shade 
 of colour, while that from the third and last purifier should pro- 
 duce no shade whatever, as it should contain no sulphuretted 
 hydrogen, and therefore produce no decomposition of the ace- 
 tate of lead. Mr. Clegg recommends that test-paper should be 
 applied every morning to the four descriptions of gas, namely, 
 to the crude gas and to that from each of the three purifiers, 
 and that test-papers should be printed with squares for each 
 kind of gas. The squares should be painted with the solution of 
 acetate of lead immediately before its application to the jet of 
 gas, and the papers preserved as a record of its purity from day 
 to day. Where nitrate of silver is used as a test the shades 
 
J66 
 
 OXIDE-OF-IRON PURIFICATION. 
 
 of colours are produced by a similar decomposition, the 
 metallic silver being in this case deposited on the surface of 
 the paper. The phial in which the nitrate of silver is kept should 
 be coated with tin foil to preserve it from the action of light, 
 which turns the solution black ; and if the test-papers are to 
 be preserved, they must for the same reason be kept within 
 the leaves of a book, or otherwise excluded from the light. 
 
 The cost of purification by lime is variable ; and when 
 practicable, wet lime is the most effective. By these means 
 a bushel of good quick -lime will purify about 20,000 cubic 
 feet of gas ; with dry lime only about two-thirds of that 
 quantity will be purified. 
 
 Mr. Croll estimated the expense of lime in London at 
 the rate of \d. per 1,000 feet. Mr. Barlow’s estimate was 
 considerably above this, being ‘46c?. This, with the labour, 
 costing about f d. per thousand feet of gas made ; but this 
 calculation only holds good in large establishments. The 
 quantity of sulphur present in the coals must also influence 
 considerably the cost of purification. 
 
 OXIDE-OF-IRON PURIFICATION 
 
 Of late years the oxide of iron has become very generally 
 adopted for the purification of gas. This has not arisen 
 from any superiority of the process, either on the score of 
 economy or effectiveness, but on account of its avoiding that 
 objectionable odour peculiar to lime purification. 
 
 The first idea of purifying gas by means of oxide of iron 
 was entertained by Mr. Heard, who had previously been 
 assistant to Mr. Winsor. That gentleman, in 1806, patented 
 a mode of absorbing the sulphur from the gas by mixing 
 lime with the coal in the retort, or by causing the crude gas 
 to pass over lime placed in an iron or other tube and exposed 
 to heat. He also stated that the oxides of iron, zinc, copper, 
 lead, &c., might be used instead of the lime. The admix- 
 ture of lime with coat in the retorts has recently been tried 
 at some works with the view of depriving the gas of the 
 sulphide of carbon ; the result has not been beneficial. 
 
OXIDE-OF-IRON PURIFICATION. 
 
 1G7 
 
 In 1840 Mr. Croll patented the means of freeing gas 
 from sulphuretted hydrogen by causing it to pass through 
 black oxide of manganese, or the oxides of iron or zinc, in 
 powder moistened with water to the same consistency as 
 lime usually employed in the dry process ; which materials, 
 after becoming saturated with the impurity, could be again 
 revived by being heated to redness in an oven, and rendered 
 fit for use, so that the same material could he used several 
 times. 
 
 By this it appears that the method of purifying now 
 generally adopted was first proposed by Mr. Croll; but on 
 account of the expense, inconvenience, and annoyance of the 
 revivification of the oxide, together with the fact that the 
 system offered no inducement for its adoption, it remained 
 dormant for several years. But as the manufacture of gas 
 increased with such rapidity, so did the nuisance arising 
 from its impurities, giving cause for serious complaints from 
 the public, and it became desirable when gas-works were 
 established in towns and cities to adopt a means of purifi- 
 cation that would avoid these evils. 
 
 In February, 1849, Mr. Laming patented, in France, a 
 system of purifying gas by means of oxide of iron inter- 
 mixed with sawdust, which, when saturated with the 
 impurity, was to be exposed to the action of the atmosphere, 
 when it would become revived and again suitable for use — 
 the same material being employed repeatedly. This method, in 
 addition to the economy, possessed the long-desired advantage 
 that very little or no odour emanated from it, which rendered 
 it peculiarly adapted for the majority of gas-works. From 
 circumstances which Mr. Laming has explained from time 
 to time he never applied for a patent for the process in 
 England. 
 
 A few months after this, Mr. F. J. Evans, of the Chartered 
 Gas Company, in making experiments with the oxide of 
 iron, accidentally discovered the same principle of revivifica- 
 cation of the material when exposed to the air, which he 
 carried practically into operation. And in November of the 
 same year, Mr. Hills obtained a patent, wherein he claimed the 
 repeated renovating or re-oxidising the oxide of iron by the 
 
168 
 
 OXIDE-OF-IRON PURIFICATION. 
 
 action of air whenever it ceased to absorb the sulphuretted 
 hydrogen, so that the same material might be used over and 
 over again to purify the gas; being substantially the same 
 method as that patented previously by Mr. Laming in France 
 
 It is generally admitted by gas engineers, that for the 
 purpose of extracting the sulphuretted hydrogen and carbonic 
 acid, no other system of purification hitherto adopted has 
 equalled the wet-lime or cream-of-lime process. But the 
 intolerable nuisance arising from the residue (technically 
 called “ blue billy ”) is such as to prevent, in many localities, 
 the use of wet-lime purification. 
 
 In using the oxide of iron for purification, it is generally 
 intermixed with sawdust, slightly moistened, and jilaced in 
 the dry-lime purifiers in layers similar to the lime, but of 
 greatly increased thickness ; and when it ceases to absorb 
 the impurity, is withdrawn and placed on a paved floor for 
 the purpose of re-oxidation, requiring to be repeatedly turned 
 over and sometimes broken up, so as to expose it to the 
 influence of the atmosphere. Considerable labour is incurred 
 in this, which is compensated by the slight expense of 
 material. 
 
 This means of purification removes effectively the sul- 
 phuretted hydrogen and cyanogen ; but for abstracting car- 
 bonic acid, lime must be employed, and, when used after the 
 oxide purifiers, little odour arises from it. 
 
 In this method of purifying, the oxide of iron and the 
 sulphuretted hydrogen are both decomposed, the oxygen of 
 the former uniting with the hydrogen, and the sulphur and 
 iron combining to form suiphurct of iron. When the 
 impure material is withdrawn from the purifiers, and exposed 
 to the atmosphere, it liberates a portion of its sulphur, and 
 absorbs oxygen, to form again the oxide of iron ; the other 
 portion of the sulphur, being precipitated, combining with 
 the iron. At each revivification the deposit of sulphur is 
 increased, and when it forms about 35 per cent, jof the mass, 
 the oxide is no longer serviceable as a purifying agent. 
 
 When the oxide of iron is fresh, when withdrawn from the 
 purifier and exposed to the air, it is very liable to ignite. 
 The general mode is to mix a portion of old material with 
 
VARIOUS MODES OF PURIFYING GAS. 
 
 169 
 
 the new in order to prevent this casualty. For the pur- 
 pose of avoiding the labour in changing the purifying mate- 
 rial, it has been proposed to exhaust a portion (about 2 
 per cent.) of atmospheric air in with the gas, so that its 
 oxygen would revive the purifying material. But if this 
 were practicable, and in such a manner as effectually to 
 absorb all the oxygen, it is certain that the nitrogen of the 
 air would detract from the illuminating power of the gas. 
 
 CHAPTER XII. 
 
 VARIOUS MODES OF PURIFYINq GAS. THE FIRST MEANS OF 
 
 PURIFYING GAS. MR. CROLl/s PROCESS OF SEPARATING 
 
 AMMONIA. PURIFYING WITH NEUTRAL SALTS. MR. 
 
 LAMING’s PROCESS. REV. MR. BOWDITCH’s PROCESS. 
 
 The first attempts at purification of gas were by means of 
 lime in the states of solution, hydrate, powder, or heated. 
 After this, numerous other processes were tried, as potash, 
 coke, salt (solid or in solution), various acids, chlorides, 
 alkaline solutions, heath wood, steam, ignited charcoal, and 
 red-hot tubes, and were all patented from time to time as puri- 
 fying agents. From the abstract of the various specifications, 
 it does not appear that the intention was to profit by the 
 impurities in gas, but merely to remove them, and when we 
 reflect on the value of the ammonia and other residues 
 derived from coal in the manufacture of gas at the present 
 time, we must admire the progress chemistry has made to 
 render these available. 
 
 Formerly ammonia was obtained principally from Egypt, 
 where it was produced from the dung of camels and other 
 animals ; however, the high price caused its use in any shape 
 to be very limited ; but of late years, in consequence of the 
 facilities afforded by gas-works for its production, the use of 
 ammonia in the arts and manufactures has become very 
 extensive, and modern chemistry has demonstrated the vast 
 
 I 
 
170 CROLl/s PROCESS FOR SEPARATING AMMONIA. 
 
 importance of this compound to agriculture, in which it is 
 largely employed. 
 
 MR. CROLL’s PROCESS FOR SEPARATING AMMONIA. 
 
 Probably Mr. Croll has been the most extensive manufac- 
 turer of ammonia in this country. This originated from a 
 patent obtained by him for the purpose of removing the 
 ammonia from gas, and retaining it in a liquid state as a 
 marketable commodity, so that it could be transported any 
 reasonable distance for the purpose of manufacture. Pre- 
 viously it was very commonly permitted to flow with the 
 liquid of the washer away into the sewer, causing great 
 annoyance, in addition to the waste. 
 
 By Mr. Croll’s process the gas, after leaving the condenser, 
 is caused to traverse a suitable vessel, which is charged with 
 a weak solution of sulphuric acid, or the chloride of man- 
 ganese, by which means the ammonia is absorbed from 
 the gas, leaving a valuable compound. The former, when 
 evaporated, producing the sulphate of ammonia, is in large 
 demand as a fertilising agent ; the latter, producing chloride 
 of ammonia, or sal ammoniac, is much used in the arts and 
 manufactures, and from it other compounds of ammonia 
 can be obtained. The vessel used is generally circular in 
 form, about 10 feet in diameter and 3 feet deep. The bottom 
 of this is formed by a circle with wooden ribs or radiating 
 bars 8 or 10 inches in depth : this wooden circle completely 
 occupies the bottom of the vessel, and supports a leaden plate 
 10 inches less in diameter than the vessel, so that a space of 
 5 inches is left all round it. Diluted sulphuric acid, consisting 
 of lbs. of acid to 100 gallons of water, are then poured 
 into the vessel up to the height of the leaden plate. The gas 
 to be purified is conducted therein by a pipe which passes 
 through the leaden plate and dips into the acid solution, the 
 divisions by which the plate is supported completely sepa- 
 rating and subdividing the gas, so as to bring each portion of 
 it in contact with the solution of acid. By degrees, as the 
 acid becomes neutralised, a regular supply of it is kept up by 
 means of a small reservoir placed outside, from which the acid 
 is allowed to drop or trickle into a funnel, and conveyed by a 
 
LIBRA R 
 
] 72 croll’s process for separating ammonia. 
 
 small tube down the side of the vessel, and brought in under 
 the leaden plate, as shown in the woodcut, Fig. 50. 
 
 The vessel is furnished with another pipe for conveying 
 away the gas to the lime -purifiers, with a small tube for 
 adding supplies of water, and with a discharging-pipe and 
 stop-cock. The original proportion of acid is kept up as 
 nearly as possible until the solution attains, when tried by the 
 hydrometer, a specific gravity of 1,170, which is nearly the 
 point of crystallisation. The supply of acid is then discon- 
 tinued, the liquor retained in the vessel, and the gas again 
 passed through until the solution becomes neutral, when it is 
 drawn off and evaporated, and yields a pure sulphate of 
 ammonia. 
 
 In large works it is preferable to use two vessels for sepa- 
 rating the ammonia, in order to insure with more certainty 
 the entire abstraction of all the ammonia, since the gas pass- 
 ing twice through the dilute acid will be better purified than 
 
 if only treated in one vessel, where there may have been an 
 accidental or temporary deficiency of acid. Two vessels of the 
 
CROLl/S PROCESS FOR SEPARATING AMMONIA. 173 
 
 size here described — namely, 10 feet diameter and 3 feet deep 
 — will purify 500,000 feet of gas in twenty -four hours, and wid 
 require to be charged with the acid solution once in two days. 
 
 Figs. 50 and 51 show the arrangement made use of by 
 Mr. Croll for purifying the gas. Fig. 50 is a section of one 
 of the vessels, each 10 feet diameter and 3 feet deep, a is the 
 inlet-pipe, passing nearly to the bottom of the vessel ; b is the 
 circular purifying vessel, lined with lead, in order to withstand 
 the action of the acid : the bottom of this vessel is composed 
 of a series of radiating plates of wood, shown in Fig. 51, 
 standing about 8 or 10 inches above the bottom. On the top 
 of these radiating bars of wood rests the leaden dash-plate, 
 as already described, c is the pipe leading from one purify- 
 ing vessel to another, and d is the pipe by which the gas 
 makes its exit ; e e are the pipes, provided with funnels, by 
 which the sulphuric acid is' added ; ff are the pipes for the 
 supply of water, and gg are the pipes by which the liquid 
 sulphate of ammonia is drawn off. 
 
 The neutral liquor drawn off from the vessels yields on 
 evaporation 80 ounces of sulphate of ammonia per gallon, 
 instead of the 14 ounces per gallon yielded. by the ammo- 
 niacal liquor separated in the condenser. 
 
 This description of the purifying process is taken from a 
 paper by Mr. Croll, read before the Institution of Civil 
 Engineers some years ago. At that time diluted sulphuric 
 acid appears to have been the contemplated purifying medium. 
 The patent, however, also included the use or substitution of 
 metallic solutions. 
 
 An impression has been entertained by agriculturists that 
 in consequence of the abstraction of ammonia before the gas 
 enters the dry -lime purifier, the waste or spent lime will be 
 deprived of much of its useful effect, hitherto supposed to be 
 due to the presence of ammonia. Mr. Croll, however, con- 
 tends that the refuse of dry lime as at present sold by the 
 Gas Companies consists merely of sulphate, carbonate, and 
 cyanuret of lime, all the ammonia being lost by volatilisa- 
 tion long before the lime can possibly be delivered from the 
 works ; hence he believes that the refuse lime possesses 
 precisely the same valuable properties as a fertiliser, while 
 
174 PURIFICATION BY MEANS OF NEUTRAL SALTS. 
 
 the noxious exhalations which accompany the escape of 
 ammonia oil the opening of the purifiers are entirely avoided. 
 
 The saturated liquor drawn from the purifying vessels after 
 being evaporated leaves sulphate of ammonia in great purity, 
 the quantity of ammonia being equal to 30 parts in 100. 
 The fertilising power of this sulphate is very considerable ; 
 and has been attested by numerous agriculturists. It is 
 said, when used as a top dressing on grass lands, to have 
 added half a ton of hay per acre to the produce, and in 
 wheat crops to have increased the weight of the wheat so 
 much as to add considerably to its selling price. About 
 1 cwt. per acre is said to be a profitable dressing either for 
 wheat or grass land. The manufacture of sulphate of am- 
 monia at the various gas-works is becoming of considerable 
 importance : many tons are already produced weekly from 
 those works where this and other processes are introduced. 
 When an increased production of this valuable article takes 
 place also, the agriculturist will be further benefited by a 
 reduction of price, as in the case of sal ammoniac and car- 
 bonate of ammonia, the price of which was formerly 3s. per 
 pound, while, since the increase of gas-lighting, and the 
 consequent production in large quantities of ammoniacal 
 liquor, a superior quality of sal ammoniac is sold for one- 
 sixth of that price. 
 
 It has been asserted that by this process the rich hydro- 
 carbons are deposited and the gas deteriorated, which circum- 
 stance would in reality take place if there were to be an excess 
 of sulphuric acid, but with a weak solution as indicated, the 
 ammonia is effectually removed and the illuminating power 
 of the gas not injured. This method, either as described, or 
 the solution of acid being pumped into the scrubbers, is em- 
 ployed at many works, and amongst them, some of the 
 largest of the Metropolis. 
 
 PURIFICATION BY MEANS OF NEUTRAL SALTS. 
 
 Recently, Mr. Croll has patented a mode of purifying 
 gas by means of neutral salts, which are combined in a con- 
 centrated form at a high temperature ; with wood saw-dust, 
 
MR. LAMING’S PROCESS OF PURIFICATION. 
 
 175 
 
 breeze, tan, or other slightly absorbent and cellular matter, 
 and employing such mixture after being allowed to cool in 
 an ordinary purifying apparatus. The salts preferred for 
 the purpose are the sulphate of alumina, the chloride or 
 sulphate of zinc, or the chloride or sulphate of iron or man- 
 ganese. 
 
 This process is in course of trial at several works, where 
 it is highly spoken of, partly for its economy, but more 
 particularly on account of the increased illuminating power 
 of gas when so purified, this increase, according to authentic 
 reports, being equal to 10 per cent. 
 
 MR. LAMING* S PROCESS OF PURIFICATION. 
 
 A method of purifying gas, patented by Mr. Richard 
 Laming, and which has been adopted by several of the large 
 Gas Companies, will now claim our attention. 
 
 This gentleman professes to proceed in a manner analogous 
 to that in which the circulating fluids of the human body 
 are purified. He observes, that the blood in circulating 
 through every part of the system absorbs and carries to the 
 various excretory organs certain superfluous quantities of 
 organic matter, which are required to be expelled from the 
 body. For example, the blood delivers over to the kidneys 
 the two elements of ammonia and those of various acids ; 
 and it conveys to the lungs a quantity of carbon, which is 
 there brought into contact with the inspired atmospheric 
 air, and combining with its oxygen is expired in the form of 
 carbonic acid. The blood thus purified from its carbon is 
 again propelled by the action of the heart to the remotest 
 parts of the body, and again becoming loaded with impuri- 
 ties, discharges them by means of the excretory organs, and 
 so the alternate process goes on during the whole period of 
 animal existence. 
 
 Mr. Laming practises a somewhat analogous process, by 
 passing the gas through a material which absorbs both its 
 carbonic acid and its sulphuretted hydrogen ; and the com- 
 pounds so formed, when again exposed to the atmosphere, 
 so as to combine with more oxygen, are again converted 
 
] 76 MR. LAMING S PROCESS OF PURIFICATION 
 
 into a material fit for purification, and may thus be used 
 over and over again in the purifying vessels. 
 
 It has long been known, that when gas is passed 
 through ordinary quick-lime, the carbonic acid combines 
 with the lime, and forms carbonate of lime. It is also 
 known, that when gas is passed through either of the 
 sesquioxides of iron, the sulphuretted hydrogen is decom- 
 posed, some of the sulphur combining with the iron, and 
 forming sulphuret of iron. Now Mr. Laming, in his 
 method of purification, mixes the quick-lime with the oxide of 
 iron, diffusing the whole through saw-dust or breeze, and 
 hence obtains in his purifying vessel the double compound 
 of carbonate of lime and sulphuret of iron. When this com- 
 pound is formed, the covers of the purifiers are removed, 
 and the mixture exposed to the oxygen of the air, when the 
 following effects take place. 1st. The carbonic acid, having 
 a very feeble affinity for the lime, quits it, and combining 
 with the iron and with another atom of oxygen forms car- 
 bonate of iron . 2ndly. The sulphur leaves the sulphuret of 
 iron, and combining with oxygen to form sulphuric acid, 
 unites with the lime, and becomes ordinary sulphate of lime. 
 The carbonic acid very soon passes off from the carbonate of 
 iron, which becomes again the oxide, while the sulphate of 
 lime remains unchanged. The sulphate of lime and the 
 oxide of iron are then again placed in the purifiers, and the 
 same changes take place when the gas again passes through 
 the mixture. It will be observed from this description, that 
 the new and important addition which has been made is 
 that of the sulphuric acid, which is formed from the sulphur 
 of the gas combined with the oxygen of the atmosphere. 
 Mr. Laming, however, observes, that instead of waiting for 
 this spontaneous formation of sulphuric acid, it may advan- 
 tageously be added at the beginning of the operation, or its 
 place may be temporarily supplied by any other acid which 
 is capable of combining with lime, and of being separated 
 from it at ordinary temperatures by carbonate of ammonia. 
 
 The principle then of Mr. Laming’s purification is the use 
 of sulphate of lime in a state of intimate combination with 
 oxide of iron. Mr. Laming states that muriate of lime, when 
 
MR. BOWDITCH’S SYSTEM OF PURIFICATION. 177 
 
 it can be conveniently procured, will do equally well with 
 the sulphate. 
 
 The inventor sums up the account of his process by 
 describing it as based upon a certain set of known affinities, 
 by the influence of which the greatest impurity of the gas, 
 namely, its sulphur, is converted into sulphuric acid, and 
 then combined with the next greatest impurity, namely, the 
 ammonia; while the carbonic acid, which is inodorous, is 
 made to escape into the atmosphere, and is thus got rid of 
 without expense. 
 
 In this mode of purification the sulphate of lime is decom- 
 posed by the ammonia of the gas, and converted into sulphate 
 of ammonia, which salt accumulates in the mass of used 
 material till it becomes inconvenient, when it is removed by 
 solution. Mr. Laming states in conclusion that his process 
 also removes from the gas its cyanogen and its sulphuret of 
 carbon, which latter is a very injurious compound, and has 
 hitherto very much retarded the admission of gas into private 
 dwellings. The inventor also attributes an excellent effect to 
 the suppression of lime, which is supposed to injure the 
 illuminating powers of coal-gas by its alkaline re-action on the 
 hydrocarbons. 
 
 THE REV. MR. BOWDITCH’s SYSTEM OF PURIFICATION. 
 
 Great difficulty has been experienced for some years to 
 find an economical and effective means of removing the 
 bisulphide of carbon from gas ; and there can be no doubt that 
 this impurity has been increased through the high heats and 
 protracted distillation often adopted in the use of clay retorts, 
 giving rise to many serious complaints on the part of the public. 
 
 The process adopted by the Lev. Mr. Bowditch, of Wake- 
 field, is very ingenious. By this, the gas is caused to pass 
 through a layer of hydrate of lime, heated to between 300° 
 and 400 o Falir., w 7 hen the bisulphide of carbon is decom- 
 posed and resolved into carbonic acid and sulphuretted 
 hydrogen, which are removed with facility by the ordinary 
 means of purification. This system has been adopted at 
 several provincial works, and Dr. Frankland’s opinion of it is 
 highly satisfactory ; that gentleman has stated, that gas so 
 
 I 3 
 
178 
 
 THE GASHOLDER. 
 
 purified does not contain more than 2 or 3 grains of sulphur 
 in the 100 feet of gas. But, according to other good autho- 
 rity, the process is injurious to the illuminating power of the 
 gas, on account of the hydrocarbons being deposed. 
 
 Report speaks highly of a method for removing the bisul- 
 phide of carbon, adopted by Mr. Leigh, chemist of the Man- 
 chester Gas Company. The process is not yet made public, 
 but shortly a description of it may be anticipated, and should 
 it be equal to expectations, will be alike beneficial to Gas 
 Companies and the public. 
 
 CHAPTER XIII. 
 
 THE GASHOLDER. CAST-IRON TANKS. SPECIFICATION OF 
 
 CAST-IRON TANKS. MR. STEVENSON’S MODE OF CON- 
 STRUCTING TANKS. BRICK TANKS. SPECIFICATIONS OF 
 
 TANK OF IMPERIAL GAS COMPANY. A SINGLE LIFT 
 
 HOLDER. SPECIFICATION OF HOLDERS. TELESCOPIC 
 
 HOLDER AT IMPERIAL STATION, HACKNEY. 
 
 The next subject for consideration is that of the gasholders, 
 or vessels in which the gas is stored ready for delivery into 
 the mains which distribute it throughout the districts to be 
 lighted. These vessels were originally termed gasometers, 
 which name is sometimes even now applied to them, but as 
 they have nothing whatever to do with the measurement of 
 gas, but are mere vessels of capacity or stores, the simple 
 name of gasholder is more expressive and appropriate. 
 
 The gasholder is composed of two distinct parts, one of 
 which contains water, and is called the tank, the other is the 
 vessel which contains the gas, being really the gasholder. 
 On the Continent the former is very generally termed the 
 “ cistern/’ and the latter the “ bell.” 
 
 The tank is a large cylindrical vessel, constructed usually, 
 for the sake of economy, of brickwork or masonry, but when 
 the ground is marshy, or when water exists abundantly a 
 short distance below the surface of the earth, which would 
 prevent the construction in masonry at a moderate price, 
 
THE GASHOLDER. 
 
 179 
 
 then tanks are made in cast-iron, and, indeed, in small works, 
 are often of wrought iron. In the interior of the tank there are 
 two vertical pipes for the admission and egress of the gas, 
 called the inlet and outlet pipes ; the former being in direct 
 communication with the manufacturing apparatus ; the latter 
 with the mains which convey the gas to the town. These 
 pipes rise a few inches above the level of the top of the tank, 
 so that the water cannot overflow into them. A series of 
 columns, generally of cast-iron, but sometimes of wood, or 
 brick piers, are placed at equal distances around the tank for 
 the purpose of guiding the holder. 
 
 The holder is a cylindrical vessel closed at the top, which 
 is termed the roof, and open at the bottom, made of sheet 
 iron, varying in thickness according to the dimensions of 
 the apparatus, the smaller sizes being constructed of thin 
 material in order to avoid an excess of pressure, whilst those 
 of very large dimensions are made of stout plates for the 
 purpose of obtaining sufficient pressure to expel the gas to 
 the burners. The holder is somewhat less in diameter, but 
 of the same depth as the tank in which it is placed, sometimes 
 being partially suspended by chains which pass over grooved 
 pulleys and counter-balance weights, but more frequently 
 only guided by rollers attached around its lower and upper 
 edges, which work against suitable guides in the tank and 
 on the columns in such a manner as to permit the holder to 
 ascend and descend in the tank with the greatest freedom. 
 
 The action of the gasholder is very simple. The tank being 
 filled with water and the holder immersed therein ready for 
 use, there is a space between the surface of the water and 
 the roof of the holder ; the gas enters by the inlet pipe into 
 this space, and with the force it acquires in being expelled 
 from the coal pressing on the surface of the water and 
 underneath the roof, and over the whole area of both, causes 
 the holder to rise. Thus, by its own force or pressure, the 
 gas provides room for itself, and in proportion to the quantity 
 entering so does the holder rise out of the water. For in- 
 stance, a holder having 100 feet area, or about 11 feet 4 inches 
 diameter, in rising 10 feet will receive 1,000 cubic feet of 
 gas, and in descending, the same quantity would be expelled. 
 
L80 
 
 CAST-IRON TANKS. 
 
 Gasholders, although often suspended, are never entirely 
 counterbalanced, having always sufficient weight to give the 
 necessary pressure to force the gas through the mains and 
 burners ; and should be so constructed that when the holder 
 is full or at its greatest height, its lower edge will be so far 
 under the water as to prevent the possibility of escape of gas. 
 
 The water in the tank serves three purposes ; it is the 
 means of resistance for the gas to lift the holder, it prevents 
 the gas escaping or intermixing with the atmosphere, and is 
 the means of expelling the gas when the holder descends. 
 
 CAST-IRON TANKS. 
 
 When the tank is made of cast-iron the pieces of which 
 it is composed are usually plates about 5 feet long and 3 feet 
 deep, having flanges all round them of 2 or 3 inches wide. 
 The flanges are cast with holes from 6 to 8 inches apart to 
 receive the bolts used for fixing the plates together. The 
 thickness of the plates vary according to the dimensions of 
 the tank for which they are destined ; in large tanks, from 
 80 to 150 feet in diameter, the bottom is formed of plates 
 varying from 1^ to 1 inch thick, and the side plates vary 
 from 1^- to 1 inch thick for the bottom tiers, and from f to 
 to § inch thick for the top tiers. The plates for smaller 
 tanks are thinner than those stated ; for a tank 25 feet 
 diameter and 10 feet deep, they are not required thicker 
 than § inch for the bottom and lower tier of sides, and ^ inch 
 or less for the top tier. In all cases it is essential to place 
 iron bands or hoops around the exterior, which are made 
 secure with cotters. 
 
 Iron tanks are made of various sizes up to 150 feet in 
 diameter, but seldom more than 25 feet deep. The columns 
 for guiding the holder are generally attached to brick piers 
 by means of holding-down bolts built in the piers. On other 
 occasions, for small holders, brackets for carrying the columns 
 are cast on the tank, but these should always be supported 
 by brick piers. 
 
 When cast-iron tanks are erected they require a suitable 
 foundation of concrete, which should be made perfectly 
 
SPECIFICATION FOR A CAST-IRON TANK. 181 
 
 level and the bottom plates securely embedded in mortar. 
 Sometimes baulks of timber, placed transversely, are used 
 instead of concrete ; but as these are likely to be destroyed 
 by rot, concrete is decidedly preferable. 
 
 The flanges of the bottom plates are always cast so as to 
 be on the inside of the tank, which gives great facility for 
 bolting and caulking the joints. The flanges of the sides are 
 generally on the outside, but sometimes, for the sake of 
 appearance, are placed inside the tank, which is, however, 
 very injudicious, for in this case, in the event of a plate 
 breaking, or a joint leaking, after the holder is in operation, 
 it is very difficult to repair. 
 
 The introduction of tanks or cisterns formed of cast-iron 
 plates to hold water can scarcely be said to have its origin 
 in gas-works, as the iron troughs or waterways constructed 
 as aqueducts for carrying the water of canals over roads and 
 valleys probably afforded the first examples of the use of iron 
 for such a purpose. Cast-iron aqueducts were common on 
 the canals executed by the late Mr. Telford and Mr. Rennie 
 some time before iron tanks were used in gas-works.* 
 
 The following abstract of a specification in Mr. Clegg’s 
 “ Treatise on Gas Lighting,” and specification extracted 
 from the “ Journal of Gas Lighting ” hereafter inserted, will 
 convey to the reader the mode of constructing cast-iron 
 tanks. 
 
 Specification for a Cast-iron Tank 101 feet in diameter 
 inside exclusive of the flanges. 
 
 “ The flanges of the bottom plates to be on the inside, and 
 the others on the outside, the whole of them to project 
 inches at the least ; the bottom of the tank to be 1 inch 
 thick throughout, excepting the outside row of plates, and 
 the row next to it. The outside row to be 1J inch thick, 
 and the next row to diminish in thickness from to 1 inch ; 
 
 * The cast-iron aqueduct which carries the Shrewsbury Canal across 
 the valley of the Tern, at Long Mill, is 186 feet in length. The Pont-y- 
 Cysylte aqueduct on the Ellesmere and Chester Canal is a far more stupen- 
 dous concern, the cast-iron trough which carries the canal being 988 feet 
 long by 20 feet wide and 6 feet deep. Both these works were executed by 
 Mr. Telford in the beginning of the present century. 
 
182 
 
 SPECIFICATION FOR A CAST-IRON TANK. 
 
 the centre plate to be 1J inch thick ; the first tier of side- 
 plates to be 1^ inch, the second 1| inch, the third 1^- inch, 
 the fourth 1 inch, and the fifth or top tier 1 inch thick, each 
 of the side-plates to be of such a width as to allow of seventy- 
 five in the circumference, each plate to be 4 feet 6J inches 
 deep, and each tier of plates to be numbered on the casting 
 of them, such numbers to be 1, 2, 3, 4, and 5, beginning at 
 the bottom tier. 
 
 “ The tank to be bound together with five wrought-iron 
 hoops, each hoop to be 5 inches wide and inch thick, the 
 tank to be bolted together with full 1 inch bolts, and not 
 more than 7 inches asunder from centre to centre of each 
 bolt, and to be properly cemented together with iron cement; 
 a flange column to be fixed on the centre plate of the tank 
 so as to support the roof of the gasholder when down. The 
 plates of the tank, exclusive of the bolts, cement, hoops, and 
 centre column, to weigh 350 tons.” 
 
 In cases where it becomes necessary to resort to the use of 
 iron in the construction of tanks, an excellent and economical 
 plan has been adopted by Mr. G. W. Stevenson, of Halifax, 
 by which he entirely dispenses with the bottom plates of the 
 tank, thus saving nearly one-half the metal that would 
 otherwise be required. 
 
 The excavation having been made in the usual way, a 
 bed of hydraulic concrete, 18 inches to 24 inches thick, 
 according to circumstances, is laid over the whole of the 
 bottom, and upon this at the outer edge is placed a circle of 
 strong stone kerb to carry the side plates of tank. 
 
 The bottom tier of plates has a flange cast on the outside 
 of each plate, which fits loosely into a corresponding groove 
 cut into the stone kerb. After all the bottom plates have 
 been fixed in the groove, the whole of the space between the 
 kerb and plates, as well as the groove, is run quite full with 
 pure cement. As a final precaution against the passage of 
 water, an additional body of concrete is placed on that 
 originally laid down, and close to the face and overlapping 
 the top of the stone kerb. 
 
 Where good strong clay can be obtained, the same plan 
 
BIlICK TANKS. 
 
 183 
 
 may be adopted in puddle, and Mr. Stevenson lias so applied 
 it in tanks upwards of 100 feet in diameter. The cost of a 
 tank, especially of large size, constructed in this manner, is 
 considerably less than when made entirely with iron sides 
 and bottom. It is obvious that this method could be adopted 
 in various ways to suit circumstances, and the material to be 
 employed. 
 
 Annular or ring tanks have sometimes, but rarely, been 
 constructed. These, when, of cast-iron, consist of two 
 cylinders placed concentric to each other, the space between 
 them being the receptacle for the water and the holder, 
 the bottom of course being plated. A tank of this kind was 
 made for the Brick-lane station of the Chartered Gas Com- 
 pany, and for the Bristol and Clifton Company. A similar 
 tank in masonry, of about 150 feet in diameter, was con- 
 structed by Mr. John Manby, in Paris, thirteen years ago , 
 but the expense of this class of construction in nearly all 
 cases prevents the system being adopted. 
 
 BRICK TANKS. 
 
 When the nature of the ground permits of the tanks 
 being constructed in brickwork or masonry, they are sunk to 
 a considerable depth, so that the top rises about 1 foot 6 inches 
 or 2 feet above the level of the ground ; but in some cases, 
 where water prevents the excavation being carried sufficiently 
 deep, tanks of brick or masonry are made to project as much 
 as 6 feet or 8 feet above the level of the surface. When this 
 occurs, they must be remarkably well constructed and of 
 increased thickness ; also, for greater security, the part pro- 
 jecting above the ground should be bound with one or more 
 iron hoops, similar to those employed in cast-iron tanks. 
 
 Generally the whole of the ground in the centre of the 
 tank is removed, leaving the bottom level ; and when puddle 
 can be procured at a moderate cost, the whole surface of 
 flooring of the intended tank should have a layer of about 
 24 : inches of that material, well tempered and trampled down 
 before commencing the building : this, as well as the puddle 
 at the back of walls, to be considered in the dimensions of 
 the excavation. 
 
184 
 
 BRICK TANKS. 
 
 The thickness of brickwork or masonry for a tank must 
 depend entirely on its size and depth. Small tanks — on 
 account of not having the same column of water to resist 
 against — require walls of less thickness than those of large 
 dimensions. Under ordinary circumstances, for a tank of 
 37 feet diameter and 16 feet deep, the base of footings should be 
 3 ^ bricks wide, with offsets on the outside for 5 or 6 courses, 
 when the wall of tank commences, which should be 2-^ bricks 
 thick at bottom, diminishing by two offsets on the outside to 
 1J brick thick at top, terminating with a stone coping, or, 
 when strict economy is necessary, a coping of brick on edge. 
 
 For a tank 100 feet diameter, and 25 feet deep, the walls 
 should be 4 bricks thick at bottom, diminishing to 2 \ 
 bricks at top ; the footings being 6 bricks wide at base, 
 gradually diminishing, as before stated, to the course where 
 the wall commences. The bottom of the tank should be 
 worked in with the upper courses of the footings. Piers 
 will also have to be carried up from the footings in order to 
 receive the holding-down bolts by which the cast-iron guide 
 columns are secured. 
 
 The nature of the ground, and the material employed, 
 will of course essentially influence a decision as to the thick- 
 ness of brickwork required in any particular case, also 
 whether concrete be necessary in the foundations. The 
 dimensions above given may frequently require to be ex- 
 ceeded, while very few cases will occur in which it would be 
 safe to diminish them. The whole of the brickwork should 
 be carried up either in Roman cement, or in the very best 
 hydraulic mortar, such as that made from the lias limestone 
 of Aberthaw, Southam, &c. Most of the common mortars 
 when in contact with water will dissolve by degrees, become 
 soft, and in time the joints will be emptied, and the destruc- 
 tive power of the water will soon show itself on the brick- 
 work ; therefore cement or hydraulic mortar must be 
 employed. The duration of a tank will materially depend 
 on the perfection of the brick-work, and the complete resist- 
 ance of the mortar joints is of the utmost importance. It 
 is usually recommended to put in the puddle behind the wall 
 in a more fluid state than it is generally used for canal 
 
BRICK TA]SKS. 
 
 185 
 
 embankments, dykes, and other hydraulic works, in order 
 that the more compressible part may enter into the pores of 
 the brickwork and form a more complete union with it. 
 The puddle should he used in thin layers of 6 or 9 inches, 
 well cut up, and well worked with water, and trodden down 
 in the usual way. The best material for puddle is not pure 
 clay, which is apt to crack, hut clay with a portion of sand 
 or silt, free from stones or other hard masses, and especially 
 free from vegetable fibre of every kind, which would in time 
 decay and leave hollows. The thickness at base of wall 
 above the footings may be 2 feet, diminishing to 1 foot at 
 top. In carrying up the brick-work of the tank, the space 
 between the puddle and the solid ground will become wider, 
 and this must be carefully filled in with earth well rammed 
 in thin courses, corresponding with the progress of the wall. 
 When stone is abundant, tanks can be constructed economi- 
 cally with blocks of about /the size of large paving-stones, 
 built in hydraulic mortar, backed with rubble masonry, the 
 walls being rather thicker than when built of brick ; a per- 
 fectly sound tank can be so constructed without puddle. 
 
 The interior of the tank is sometimes flat, at others a 
 mound, cone, or dome is left in the centre. When the 
 ground presents no difficulty, it is cheaper to make the centre 
 nearly flat ; but should the foundations be under water, then 
 the mound in the centre has an advantage, as it avoids 
 excavating, concreting, or puddling under water. 
 
 But in some localities neither puddle nor bricks are to be 
 obtained, when recourse must be had to the building material 
 of the country, and this, in some of the islands of the 
 Mediterranean and elsewhere, consists almost entirely of 
 freestone, which serves alike for walls, roofs, and often 
 flooring, thus replacing bricks, tiles, and boarding. In such 
 places a more suitable material for gasholder tanks can only 
 be procured at a most extravagant cost ; nevertheless, even 
 with this material, a good and sound tank can be constructed 
 without the aid of puddle, 
 
 For this object the stone is obtained in suitable blocks, and 
 faced to the required curve, the foundation or flooring being 
 composed of concrete ; the wall is built with Roman or 
 
186 
 
 BRICK TANKS. 
 
 Portland cement, &c., well backed with rubble and hydraulic 
 mortar. When the tank is finished, and allowed to dry, all 
 the interior is well coated with good thick tar, which stops 
 all the pores of the stone. 
 
 A natural production from Italy, called Puzzolano, 
 resembling in appearance, when in powder, the red oxide of 
 manganese, is very excellent for rendering ordinary lime 
 hydraulic. Previously to being used, it should be ground 
 to a powder, and mixed in the proportion of one of puzzo- 
 lano, to three or four of lime slacked, and the corresponding 
 quantity of sand, to be made into mortar. Foundations of 
 concrete with this mixture set under water in a few days, and 
 become as hard as any cement. Puzzolano was used in the 
 construction of Eddystone Lighthouse ; but, although much 
 employed on the Continent, it is seldom adopted in England. 
 
 The following is a specification, extracted from Mr. Clegg’s 
 “ Treatise on Gas Lighting,” of a brick tank 31 feet 6 inches 
 diameter : — 
 
 “ Excavation . — The ground to be dug out to the depth of 
 II feet 6 inches, of such diameter as may be requisite, with 
 such slopes to the sides as will prevent them from slipping in. 
 Should any part show a tendency to slip, it must be immedi- 
 ately shored, and the shores must be maintained so as not to 
 interfere with the building of the walls. The excavation 
 must be kept clear of water till the gasholder is fixed and 
 the scaffolding removed. Well-tempered clay puddle of 
 approved quality to be used for the covering of the bottom 
 of the tank, and for coating the outside of the side walls, 
 in the following thicknesses, — over the bottom of the tank, 
 2 feet 6 inches ; on the side walls, 2 feet 6 inches, reduced to 
 1 foot 6 inches at the top ; the whole to be well trodden in 
 and backed up as finished.” 
 
 “ Brickwork . — The bricks to be hard, well-burnt stocks ; 
 the whole of the mortar must be of the best hydraulic lime 
 and sharp river sand, well mixed, and thoroughly worked 
 together, and in the proportions of a third lime to two-thirds 
 sand. Two double courses of footings with sets off — of half 
 a brick for each double course ; the remaining portion of the 
 wall to be divided into two parts — one 8 feet 6 inches high, and 
 
BRICK TANKS. 
 
 187 
 
 2 bricks thick, and the other 3 feet 6 inches ; the walls to be 1^ 
 brick thick, the last or top six courses to be laid in the best 
 Roman cement ; the whole work to be grouted with its 
 respective mortar or cement every four courses. The tank 
 to form a perfectly true circle, neither more nor less than 
 31 feet 6 inches in diameter in any direction. Seven piers to 
 be built equidistant around the circumference to receive seven 
 stones hereafter described. One pier to be built outside 
 on the main point of suspension, with dry well of 9 inches 
 work, of 2 feet 6 inches in diameter, and 3 feet 6 inches deep, for 
 counterbalance weights. Two of the piers to be built at the 
 secondary points of suspension ; in these piers holding-down 
 bolts and plates to be built in and run in with Roman cement. 
 Three other piers are also to be formed by carrying up the 
 two -course brickwork in the wall solid to the top for 2 feet 
 6 inches in width.” , 
 
 “ Masonry . — Seven squared and tooled stones to be set in 
 cement, 2 feet by 1 foot 6 inches by 6 inches, for inside piers, in 
 which there must be formed holes for six lock nuts ; also three 
 stones, 24 inches by 27 inches by 4 inches thick, for the hold- 
 fasts for the girder rods. One square and tooled stone for the 
 cap of the main pier 6 feet by 2 feet by 1 foot, with a portion 
 cut out to allow the balance weight to pass, and holes for the 
 foundation bolts, and cases for the foundation bolts and case 
 of columns. At each of the two secondary points, also squared 
 and tooled stone caps, 3 feet by 2 feet 6 inches and 1 foot thick, 
 with holes for the foundation bolts and case of columns.” 
 
 According to the same authority, the following is the 
 estimated cost of a lank 36 feet diameter and 12 feet deep. 
 
 £ s. d. 
 
 752§ cubic yards of excavation at Is. . . . . . 37 12 8 
 
 107 ditto of puddling, at 1 s. 6d 8 0 6 
 
 246 superficial feet of York flagging under wall, Is. 9<A 21 10 6 
 
 5J rods of brickwork and mortar, at <£12 10s. . 68 ] 5 0 
 
 119 cubic yards of puddling and filling in behind 
 
 wall, l*.6d 8 18 6 
 
 30 cubic feet of Bramley fall stone for base of 
 
 tripods, 4s. 3 d 676 
 
 374 cubic yards of earth carted away at 2s. 2 d. . 37 1 10 
 
 £188 6 6 
 
188 
 
 BRICK TANKS. 
 
 The foregoing details of estimate will serve a3 a guide of 
 the cost in the construction of a brick tank of moderate 
 dimensions, but when of very great magnitude and depth, 
 the price of some of the items will require augmentation. 
 
 One of the most remarkable constructions of this kind is 
 the tank built at the Pancras station of the Imperial Gas 
 Company. The excavation is entirely in London clay, and 
 it was originally intended by the engineer, Mr. Metliven, only 
 to build the circular wall, leaving the centre without either 
 masonry or any other protection, relying entirely on the clay 
 in the middle to retain the water. But, on excavating to the 
 depth of about 35 feet, it was found that the soil became of a 
 loamy nature, which rendered it necessary, as a matter ot 
 precaution, to cover the lower part of the cone to the height 
 of about 20 feet with three or four courses of brickwork, 
 the upper part, as well as the top of the cone, being clay only. 
 Although of such extraordinary depth and dimensions, the 
 tank is perfectly tight and secure. Herewith is subjoined 
 an abstract from the specification : — 
 
 Specification of Brick Tank, 145 feet diameter and 45 feet 
 deep , constructed at the Imperial Gas Company's Works , 
 Pancras Station . 
 
 “ The tank, when finished, to be a perfect cylinder of 
 145 feet internal diameter, and 55 feet deep ; the top of 
 coping of tank to be 4 feet above the present surface level. 
 
 “ The earth to be excavated for the foundation of the wall 
 around the entire circumference of the tank to the depth of 
 53 feet from the present surface level. The ground to be 
 shored when the excavation shall have reached the depth of 
 6 feet from the surface, and this shoring to consist of 3-inch 
 planks, placed close to each other around the entire excava- 
 tion, with strong walling pieces and struts. 
 
 “ When the wall shall have been completed, the earth in 
 the centre of the tank to be removed to the extent shown on 
 sectional drawing, leaving a cone 6 feet less in diameter at 
 the base than the interior of the tank, and to taper at such an 
 angle as that, at the depth of 15 feet below the finished heigh 
 of the wall, the cone shall be 30 feet diameter. 
 
BRICK TANKS. 
 
 189 
 
 a Brickwork . — The first eight courses of tank wall and 
 piers to be set in Roman cement. The first, second, third, 
 and fourth double courses of footings to be respectively 5 feet, 
 4 feet 8 inches, 4 feet 4^ inches, and 4 feet in thickness. 
 The seventh course to commence the net-work of that portion 
 of the wall, which will be 3 feet 7 inches, or 4J bricks in 
 the thickness, to the height of 10 feet above footings. The 
 remaining height of wall to be reduced as follows, viz. : from 
 10 feet to 20 feet from bottom of net brickwork to be four 
 bricks thick ; from 20 feet to 30 feet in height three and a 
 half bricks ; from 30 feet to 45 feet three bricks ; from 45 feet 
 to 50 feet two and a half bricks in thickness ; and the re- 
 maining 4 feet, exclusive of coping, to be two bricks thick. 
 
 “ There will be sixteen piers, 4 feet 3 inches wide, for the 
 support of cast-iron columns, and built up with the wall. 
 
 “ Six courses of brickwork in every 5 feet of height, as 
 also the three finishing courses, and the corresponding 
 courses in piers to be set in cement. The brickwork at no 
 part to be carried higher than 5 feet, until the circle up to 
 that level shall have been completed, and properly tempered 
 puddle filled in behind the wall. 
 
 “ A cast-iron plate and holding-down bolts to be built into 
 each of the piers 10 feet below' the level of the coping. The 
 standpipe well to be a true cylinder 15 feet in diameter, the 
 foundation of which will be 63 feet deep from the level of the 
 coping of the tank ; the bottom to be perfectly level, and 
 paved with three courses of bricks on edge and set in cement ; 
 the footings of the wall to start from the same level as the 
 deepest portion of the wall of tank to and from an integral 
 portion of the same. 
 
 “ There are to be thirty -two piers of brickwork built in 
 the bottom of the tank for the foundation of rest-stones, 
 the same to form part of the general footings of the tank, 
 each pier to be capped with a stone, a recess of 4J inches to 
 be left in the face of the tank wall for the insertion of these 
 stones. 
 
 “ Stonework . — In addition to the stones above mentioned, 
 there will be required blocks of stone, 18 inches by 12 by 
 12 inches, to be inserted in the wall of the tank opposite to 
 
190 
 
 BRICK TANKS. 
 
 and at points equidistant from each pier at the height shown 
 in drawing. 
 
 “ There are also to be sixteen stones 5 feet square and 
 18 inches thick to cap piers for the support of the guide 
 columns of the holder. In each of these, four holes are to be 
 pierced for the holding-down bolts. The wall of tank to be 
 surmounted by a coping 12 inches thick, to be bedded in 
 cement. The whole of the stones to be Greenmore orBram- 
 leyfall description. 
 
 “ Timber -framing . — For the support of the roof of the gas- 
 holder when down, a wooden frame to be constructed in the 
 manner shown in drawings; the piles, to be not less than 12 
 inches by 12 inches square, of suitable lengths, and iron shod, 
 are required to be driven into the cone, and to these piles will 
 be attached radiating and circular timbers as shown. The 
 radiating timbers to be let into the top of the piles and pro- 
 perly fastened by f-inch bolts; the circular timbers to be pro- 
 perly scarfed, let into those radiating from the centre, and 
 firmly secured by wrought-iron knees and spikes. 
 
 “ Material . — The bricks employed on the w’ork to be of 
 the best hard-burnt stocks. The mortar to be composed of 
 one part of fresh burnt lias lime, to three parts of clear, sharp 
 river sand. The Boman ceme*nt to be fresh burnt, and 
 gauged in equal proportions with sand as above, the cement 
 to be mixed as it is being used, and no more mortar than 
 sufficient for one day’s work to be made at one time. 
 
 “ The contractor to supply all materials of every descrip- 
 tion here specified, and to provide all scaffolding, struts, and 
 shoring which may be required, the same to remain his 
 property when the work is terminated. 
 
 “ Pumping . — The contractor, during the progress of the 
 work, to find the necessary pumps and labour to keep the 
 tank dry ; to employ competent men to watch at all times, 
 and strut or shore up any signs of slip or yielding of the 
 earth, and to make good at his own cost any damages what- 
 ever which may occur from rain or otherwise. 
 
 “ All superfluous earth or clay, not required for filling in 
 or puddling, to be carted away at the expense of contractor. 
 The puddle to be kept constantly well moistened, and not to 
 
THE HOLDER. 
 
 191 
 
 be at any pointless than 18 inches in thickness, and the earth 
 to be firmly pounded in behind as the brickwork proceeds. 
 
 “ Extra Work . — No extra work to be allowed but such as 
 shall be ordered in writing by the company’s engineer, and 
 addressed either to the contractor or his clerk of the works. 
 
 “ Terms of Tender . — The proposed contractor to state the 
 sum for which he will execute the work herein specified 
 according to its true intent and meaning connected with the 
 drawings.” 
 
 This tank completed cost upwards of <£11,000. 
 
 ON THE GASHOLDER, OR HOLDER. 
 
 There are two kinds of gasholders ; the one called the 
 single lift, consisting simply of a cylindrical vessel in the tank 
 as already described and represented in Fig. 52, which has a 
 quarter part removed to show one of the pipes, and the 
 manner the roof is supported. The stand-pipe well is shown 
 in section, with one of the two pipes and syphon at the 
 bottom. The holder is about 42 feet in diameter, and 16 feet 
 deep, and has six cast-iron columns, which serve for guides 
 for the rollers on top of holder, attached to each other at 
 the top by cast-iron girders. 
 
 The holder, when raised by the action of the gas, has very 
 little strain upon it, and only when empty, or when it touches 
 the ground, do the roof and sides require any support. For 
 this object roofs are sustained generally by “ trussing.” This 
 trussing consist of a series of radiating bars of T or flat bar 
 iron, diverging at equal distances from the centre plate, called 
 the “ crown plate,” to the angle iron or top curb, or angle of 
 the holder. The roof is sustained by a king-post in the 
 centre, which is supported by tension rods from the top curb ; 
 there are also suspension rods which carry struts for sustaining 
 the centre of radiating bars. A series of circles of rafters at- 
 tached to the radiating bars complete the trussing of roof. 
 The sides in large holders have also trussing to prevent the 
 holder “ bulging ” or “ buckling ” when on the ground. 
 
 In holders of great dimensions the trussing enters for a large 
 portion of the expense ; in addition it greatly increases the 
 
0 0 0 0 0 0 o~o~o O 
 
 192 
 
 THE HOLDER. 
 
THE HOLDER. 
 
 193 
 
 weight, and, in consequence, the pressure, which is often by 
 no means desirable. It is a very important consideration 
 in the erection of gasholders, to adjust them so that the 
 pressure of the gas enclosed in them be not much more 
 than the maximum pressure required to supply the town or 
 locality, Whenever an exhauster is not employed, any 
 excess of pressure acts seriously on the retorts, causing a 
 large increase in the carbonaceous deposit in them, the gas 
 being in consequence deteriorated ; the fuel and labour are 
 also increased, and the production of gas materially diminished ; 
 and even when the exhauster is used, any superfluous pres- 
 sure on the holder throws unnecessary labour on the engine, 
 and of course requires more fuel. 
 
 When holders are suspended by counterbalance weights, 
 the excess of pressure can generally be considerably reduced 
 by placing extra weights, and in many small works, where 
 the holder is not suspended, the loss is of importance. 
 Therefore all small holders, particularly when there is no 
 exhauster, should be counterbalanced in such a manner as 
 to be enabled to give the maximum pressure required in 
 the locality, but no more. 
 
 Gas engineers are not unanimous in opinion as to the 
 necessity of trussing the roofs of holders. The majority adhere 
 to the old system of trussing, whilst others dispense with it 
 entirely. In that case, when the holder is empty, or on the 
 ground, its roof is supported by a series of vertical props or 
 pillars with radiating bars in the tank, as described in the 
 specification of Imperial Company’s tank. Without doubt 
 this system has several advantages, being simpler, cheaper, 
 and possessing the same durability as when trussed. 
 
 A gasholder 100 feet diameter and 25 feet deep, when 
 trussed, weighs about 100 tons, and gives a pressure of about 
 5J inches of water, and of this weight about 30 tons consist 
 of trussing. Now, if we suppose a pressure of 3 inches to be 
 adequate to supply a district, it is obvious the extra pressure 
 must be prejudicial. In this case, if the trussing were dis- 
 pensed with, the holder would be so much lighter as to give 
 only the 3 inches pressure desired, whilst its strength and 
 durability would be retained. 
 
 K 
 
THE HOLDER. 
 
 194 
 
 We may, however, assume the pressure of 5J inches 
 actually necessary in order to supply a given district, when 
 the weight would be indispensable, and under these circum- 
 stances it would be certainly wiser to obtain the increased 
 weight by increasing the thickness of the plates of the holder, 
 thereby rendering it of much greater durability, instead of 
 applying the material as trussing. Many eminent engineers 
 now prefer the roofs of gasholders without trussing, and this 
 opinion is gaining ground daily. 
 
 The thickness of plates commonly used in the construction 
 of gasholders varies from No. 18 to No. 11 wire gauge, the 
 first of these being less than ^th of an inch in thickness, 
 weighing 1*86 lbs. per square foot, while the other is |th of 
 an inch, and weighs 5 lbs. per foot. In very large holders 
 plates are considerably thicker than these, in order to obtain 
 the necessary pressure for supplying the district. 
 
 The pressure of gas enclosed is dependent on the total 
 weight of the holder containing it, and on the area of its top. 
 The water in the tank being the resisting medium to the 
 pressure, a quantity of this, equal in weight to that of the 
 holder, is always displaced by the latter rising. Thus, by a 
 knowledge of the pressure, given by a holder, and the area of 
 the top of vessel, a close approximation of its weight may be 
 ascertained ; and, on the contrary, the weight and area being 
 given, the pressure is readily known. 
 
 For this, and many similar purposes, the weight of a cubic 
 foot of water is the basis of calculation, this being 62^ lbs. ; 
 therefore a column of water exactly 1 foot square and 12 
 inches high, is equal to 62-| lbs., or a column of same area, 3 
 inches high, 15*625 lbs., or 1 inch high, 5* 24 lbs., &c. 
 
 If, therefore, it be required to ascertain the weight of a 
 holder giving a certain pressure, say 3 inches when full, and 
 the sides nearly out of the water, then, on multiplying the 
 area, of the top in feet by the weight corresponding to a 
 column of water of the height of pressure, the weight is ascer- 
 tained. For example, a holder is 11 feet 4 inches in diameter, 
 its area being 100 feet, giving 3 inches pressure, then 100 
 multiplied by 15*625 lbs. gives 1,562^ lbs. as the total weight 
 of holder. Or, the weight being given, the pressure is calcu- 
 
THE HOLDER. 
 
 195 
 
 lated by dividing the total weight by the area in feet, when 
 the weight of a square foot is found, from which the pressure 
 the holder will give is known, thus reversing the figures just 
 mentioned ; 1,562^ lbs. divided by 100 feet gives 15*625 lbs., 
 corresponding to a column of water 3 inches high or that 
 pressure. 
 
 By the same means, if it be requisite to know the weight 
 required to be placed on a holder to produce a certain 
 increased pressure, then the weight of column of desired 
 pressure multiplied by the area of top of holder in feet gives 
 the weight. Thus, if the pressure of the before-mentioned 
 holder requires to be augmented say 1 inch, that is, from 
 3 inches to 4 inches, then the weight of a column of 1 inch 
 being 5*24 lbs. multiplied by the area of top, gives 524 lbs. 
 as the necessary weight. These calculations are approxi- 
 mative ; for them to be rigidly exact, the holder should be 
 filled with air, or an allowance made for the specific gravity 
 of the gas. The same rule applies to the weight of gover- 
 nors, pressure registers, &c. 
 
 When a holder is nearly at the bottom, and its side plates 
 immersed in water, it becomes somewhat lighter, and in con- 
 sequence the pressure is less than when it is full and the 
 sides out of the water. Many attempts have been made to 
 remedy this, but the difference is so slight, being 2 or 3 
 tenths, as to render any means to prevent it quite unne- 
 cessary. 
 
 Mr. Clegg gives an example of a gasholder 36 feet in 
 diameter and 12 feet deep, made of No. 18 wire gauge for 
 the sides, and No. 17 for the top; total weight of gasholder, 
 6 tons 5 cwt. 2 qrs. 21 lbs. ; tripods, or columns and guide 
 rods, 5 tons 2 cwt. 1 qr. 21 lbs. Total cost of gasholder, 
 including erection, £247 10s. 
 
 Another example is a gasholder 50 feet diameter and 18 
 feet deep, containing 35,300 feet ; top, No. 14 wire gauge ; 
 sides, No. 15 ditto ; total weight of gasholder, 12 tons 18 
 cwt. 2 qrs. 27 lbs.; tripods and guide rods, 11 tons 6 cwt. 
 3 qrs. Cost, including erection, <£541 2s. 
 
 Another instance is a gasholder 871 feet diameter and 25 
 feet high, which cost, including erection, £1,609 10s. 
 
 K 2 
 
196 
 
 THE HOLDER. 
 
 The gasholder erected by the Imperial Company for the 
 tank already mentioned, being 112 feet diameter and 55 feet 
 deep, cost nearly <£8,000. 
 
 The following specifications will, no doubt, be of interest 
 to the generality of readers. 
 
 Specification for a Single Lift Gasholder , 10 feet diameter 
 and 15 feet deep . 
 
 “ Crown Plate . — The crown or centre plate of roof of gas- 
 holder to be 3 feet 5 inches in diameter, and inch thick, 
 with twelve bolt-holes for receiving the bolts to secure the 
 ends of main bars. 
 
 “ Centre Pipe and Truss Cup. — The centre pipe for trussing 
 to be of cast iron, 1 inches diameter and 6 feet long, the 
 upper end secured to the crown plate with four f-inch bolts. 
 At the lower end of the centre pipe is to be secured a cast- 
 iron truss cup 2 feet 6 inches diameter, the outer rim of 
 which is to have twelve holes for receiving the ends of ten- 
 sion rods. 
 
 “Main Bars. — To be twelve main bars of T iron, 2f inches 
 X 2f inches X f inch ; the upper ends of which are to 
 be secured to the crown plate with 1-inch bolts and nuts; 
 the lower ends secured to the top curb ; four of the main 
 bars to be prepared at the lower end for securing to both the 
 top curb and also to a vertical stay. 
 
 “ Trussing. — Each main bar to be trussed in the manner 
 shown on diagram ; the tension rods to be § inch diameter, 
 enlarged at the screw end to 1 inch diameter ; the suspension 
 rods to be § inch diameter, the upper end formed into a jaw, 
 and secured to the main bar with a f-inch bolt, the lower 
 end formed into an eye through which the strut will pass ; 
 the strut to be 1J inch diameter, the upper end formed into 
 a jaw and secured to the main bar with a f-inch bolt, the 
 lower end to be screwed and secured to the tension rods and 
 suspension rods, with tw r o nuts on each. 
 
 “ Vertical Stays. — To be four vertical stays for supporting 
 the sides of the gasholder, of J iron 3 inches x 2f inches 
 X f inch, the upper end connected with the top curb and 
 
THE HOLDER. 
 
 197 
 
 main bars, and the lower end to be secured to the bottom 
 curb with ^-inch bolts. 
 
 “ Top Curb . — The top curb to be of angle iron 3 inches X 
 3 inches X f inch, curved to a radius of 20 feet, and neatly 
 jointed and secured with proper joint plates. 
 
 “ Bracket Bars or Purlins . — To be three rows of bracket 
 bars or purlins, bolted between the main bars with |-inch 
 bolts. The first row to be of angle iron 2 inches X 2 inches 
 X J inch ; the second row to be of angle iron 2 inches X 2 
 inches X £ inch ; the third row to be of angle iron 2£ inches 
 X 2^ inches X inch. 
 
 “Bottom Curb . — The bottom curb to be of angle iron 
 3 inches X 3 inches X f inch, curved to a radius of 20 feet, 
 and neatly jointed and secured with proper joint plates. 
 
 “Sheets. — The roof to be covered with sheets No. 14 Bir- 
 mingham wire gauge in thickness, and the sides with sheets of 
 the following thicknesses, viz., the top and bottom rows to be 
 No. 14 Birmingham wire gauge, and the remainder of side 
 sheets to be No. 15 Birmingham wire gauge in thickness. 
 
 “Manhole. — To be one manhole ring, with cover and set- 
 screw, placed in a suitable position on the roof. 
 
 “ Rivets , dec. — The rivets for the sheets to be J inch dia- 
 meter, and 1 inch apart from centre to centre. The rivets 
 for the top curve to be \ inch diameter, and lj inch apart. 
 The rivets 'for the bottom curve to be J inch diameter, and 
 G inches apart. The joints of the sheet to have a hemp-string 
 inserted during the time of riveting. Each sheet to be 
 hammered perfectly level before being punched. They are 
 then to receive one coat of linseed oil before being exposed 
 to the weather. 
 
 “Painting. — The whole of the before-mentioned work to 
 receive two coats of oxide paint in oil during or immediately 
 after erection. 
 
 “Columns. — To be four cast-iron columns, each 17 feet 
 long, 9 inches diameter at the bottom, and 7 inches diameter 
 at the top ; a guide rib to be cast on for the gasholder pulleys 
 to work against ; the base to have three holes for bolts. 
 
 “ Holding -down Bolts. — Each column to be secured to the 
 stone-work of tank with three holding-down bolts about 
 
198 
 
 THE HOLDER. 
 
 7 feet long X 1| inch diameter, with cast-iron foundation 
 washers, cotters, nuts, and washers. 
 
 “ Guides in Tank . — Four cast-iron guides in tank for the 
 gasholder pulleys to work against, each guide secured to tank 
 wall with six ^-inch bat bolts run with lead. 
 
 “ Girders. — The top of columns to be connected together 
 with a girder of T iron 3 inches X 4 inches X i inch, each 
 trussed with a f-inch rod and a 1-inch strut; each end of 
 the T iron to be secured to column cap with a f-inch bolt. 
 
 “Pulleys. — On each column cap is to be a set of pulleys and 
 fixings for the balance chains to work over. 
 
 “Chains. — Four sets of ^-inch chains with pins and 
 shackles for carrying balance weights. 
 
 “Balance Weights. — To supply 40 cwt. of cast-iron balance 
 weights to regulate the working pressure of the gasholder. 
 
 “Pulleys. — Four sets of pulleys and fixings on top, and four 
 sets of pulleys and fixings on bottom of gasholder, to work up 
 columns and tank guides. 
 
 “Painting. — The whole of the cast-iron work to receive 
 one coat of oil paint before leaving the works. 
 
 “Scaffolding. — To supply all necessary scaffolding and 
 tackle for the erection of gasholder, columns, &c., and to fix 
 the whole in a good and workmanlike manner.” 
 
 The price of this complete, delivered and fixed in London, 
 would be about £296. 
 
 Specification off Apparatus, consisting of Gasholder , Condenser , 
 Purifiers , Roof for Retort House , Retorts complete , with 
 accessories for a small works . 
 
 “ Gasholder to be 35 feet in diameter and 12 feet deep at 
 sides, the centre jdate to be 3 feet 6 inches diameter, and 
 gths of an inch thick. The crown sheets to be of No. 15 
 Birmingham wire gauge, and the sides No. 16 ditto, and to 
 be of the best Staffordshire plates. The top and bottom 
 curbs to be of 3-inch angle iron. To have four main bars of 
 3-inch T iron, four secondary bars of 3-inch T iron. The 
 centre pin to be of l-^-inch iron attached to cast-iron cup. To 
 have four tension rods of 1-inch iron, from centre cup to 
 
THE HOLDER. 
 
 199 
 
 angle iron, opposite to each column. Eight rollers and 
 frames to be fixed on bottom curb of gasholder at equal 
 distances. Four sets of guide wheels, carriages, and frames, 
 to be properly fitted and fixed, and four suspension chains, 
 with 3 tons of counterbalance weights. 
 
 “ To provide four cast-iron columns 13 feet 6 inches long, 
 6 inches diameter at bottom, and inches at top, with guide- 
 rib cast thereon, each to be fastened to pier by four holding- 
 down bolts of 1-inch round iron, and 4 feet long, and to be 
 screwed at one end with nuts. To provide and fix before 
 tank walls are commenced two 4-inch duck’s-foot bends ; 
 two 4-inch tank syphons, and two flange and spigot pipes, 
 and sufficient socket pipes for inlets and outlets, which are to 
 be fixed when required. 
 
 “ The gasholder to have two coats of paint before leaving 
 the contractor’s works, and to be fixed at the Company’s 
 premises, left perfectly gak-tight, and finished in a workman- 
 like manner. 
 
 “ To provide three cast-iron purifiers, to be 4 feet square 
 internally, and 2 feet 6 inches deep, with 9-inch dips. Three 
 covers for purifiers of No. 8 gauge plate, with lifting tackle 
 and chains complete. The purifiers to be worked by a 
 centre valve so as to allow two purifiers to be used at one 
 time. There are to be four tiers of perforated iron sieves in 
 each purifier to be supported by T iron rafters, the whole to 
 be finished and left in complete working order. 
 
 “ To provide a cast-iron condensing box, with divisions, and 
 ten 4-inch pipes each 9 feet long; four semi-circular bends, 
 each 1 foot 9 inches long, having suitable bonnets ; also to 
 provide sufficient 4-inch pipes to make the connection 
 between the condenser and gasholder, with two 4-inch 
 valves. 
 
 “ To provide and erect an iron roof 24 feet X 24 feet in 
 the clear for retort house, to consist of four pairs of principal 
 rafters, to be made of T iron properly trussed with wrought 
 iron laths to support slates, and a wrought-iron louvre for 
 ventilation. 
 
 “Also to provide and erect the undermentioned castings 
 and iron -work : — 
 
200 
 
 THE HOLDER. 
 
 “ Six cast-iron D retorts, 7 feet 6 inches long, 15J x 13| 
 internal measure. 
 
 “ Six cast-iron mouth-pieces with sockets for same. 
 
 “ Twelve wrought-iron doors for mouth-pieces. 
 
 “ Six cast-iron 4-inch flange and spigot ascension pipes. 
 
 “ Six cast-iron 4-inch H pipes and bonnets. 
 
 “ Six cast-iron 4-inch dip-pipes. 
 
 “ Hydraulic main (12 feet) with cover and end plates, to be 
 1) shaped, 12 inches by 12 inches, with three cast-iron 
 crutches. 
 
 “ Six cross bars, screw ears, and cotters. 
 
 “ Three evaporating pans. 
 
 “ Three furnace doors and frames. 
 
 “ Three dead plates and furnace bars. 
 
 “ Ten cast-iron buckstaves, and the corresponding wrought- 
 iron tie rods screwed at ends. 
 
 “ Nine sight-boxes and plugs ; to provide and fix the pipes 
 to communicate the various apparatus together. 
 
 “ Set of stoking tools, one iron barrow, one wooden barrow. 
 
 “ All the above work to be fixed complete within thirteen 
 weeks from day of order, and the whole to be done in a 
 manner satisfactory to the engineer of the company.” 
 
 The price of this apparatus was £845. 
 
 Specification for the Construction of a Gasholder for the 
 Imperial Gas Company at their Pancras Station. 
 
 “ To be a single gasholder, 142 feet in diameter and 55 
 feet deep, constructed in a tank 145 feet in diameter. 
 
 “ The roof to be without trussing or framework, as shown 
 in drawing, and when finished the crown in centre to rise 
 2 feet above the level of top curb. The top curb to be a 
 circular chamber or girder, in section nearly rectangular, 
 being 18 inches deep at the outer diameter, and 19J inches 
 at the inner diameter, and 2 feet 6 inches in width. The 
 curb to be constructed of 4-inch X 4-inch X i-inch angle 
 iron; the under and inner sides to be of |-inch wrought-iron 
 plates, riveted to angle iron with f-inch rivets. The top 
 
THE HOLDER. 
 
 201 
 
 to be of | -inch plates, which will also form the first or outer 
 row of plates of roof ; the other side to be ^-inch plates, and 
 will be the top tier of the side of holder. 
 
 “ The bottom curb to be formed of two circles of f boiler- 
 plates 12 inches wide, each riveted to a circle of angle iron 
 4 inches X 4 inches x inch. One of these to be riveted 
 to the bottom of the l -inch plate, which forms the lowest tier 
 of side of holder, the other circle to be riveted to the same 
 12 inches higher up than the former. Two stiffening plates 
 at distances of 2 feet apart are to be inserted between the 
 curb plates at 32 points of the circumference of the gasholder, 
 where the bottom guide-rollers will be attached. These 
 stiffening plates to be fixed to the curb plates and the bottom 
 plates of the holder by 2^-inch x 2^ -inch X f-inch angle 
 iron, riveted with •J-inch rivets, the plates to be f inch thick. 
 The angle iron and plates forming the bottom curbs to be 
 butt-jointed with lapping pieces of the same thickness not 
 less than 18 inches long. 
 
 “ The vertical stays to be in section three sides of a rectan- 
 gular figure 12 inches wide and 10 inches deep, to be formed 
 of four angle irons 3 inches X 3 inches X f-inch and ^--inch 
 boiler plate. There will be thirty -two vertical stays, which 
 will be riveted to top and bottom curbs, and to the plates 
 forming the holder. 
 
 “ The first or outside row of plates of roof to be 3 feet 
 long, and f inch thick, riveted to the angle iron of top curb 
 and to each other w 7 ith f-inch rivets, 2J inches apart ; the 
 second row of plates to be also 3 feet long and \ inch thick, 
 riveted to the outer row and to each other by -r 6 - rivets, 2^ 
 inches apart. The remainder of the plates of the roof, 
 except those forming a circle of 30 feet diameter in the 
 centre, to be A inch thick, or of No. 7 wire gauge, to be 
 about 5 feet long, and riveted to each other by f-inch rivets 
 1£ inch apart. The plates in the centre to the diameter of 
 30 feet to be ^ inch thick, to be butted together and riveted 
 to each other by means of lapping pieces 3^ inches wide, 
 and i^-inch rivets. 
 
 “ The top and bottom side plates to be £ inch thick and 
 riveted to the angle irons of top and bottom curbs with 
 K 3 
 
202 
 
 THE HOLDER. 
 
 W-incli rivets, and to each other and adjoining plates with 
 2 -inch rivets 1J inch apart. The intervening plates to be 
 No. 10 wire gauge riveted to each other with -|-inch rivets 
 inch apart. 
 
 “ There are to be 16 guide pulleys fitted on carriages on 
 top of gasholder, each pulley to be 15 inches diameter, with 
 flanges projecting 4 inches. Each carriage to be bolted to 
 both angle irons of the top curb, also to that on the side of 
 gasholder, by eight 1-inch bolts. There are also to be 
 32 guide rollers and carriages fitted to both angle irons of 
 bottom curb by six 1-inch bolts. 
 
 “ There are to be 16 guide columns and girders of the 
 pattern shown in drawings ; the columns to be 3 feet 
 diameter at base, diminishing to 2 feet 3 inches under the 
 capital, the thickness of metal not to be more than £ inch at 
 base, and § inch at top ; each column to be cast in not more 
 than four lengths, which will be fitted together by internal 
 flanges, the different lengths to be faced true and bolted 
 together by eight 1^-inch bolts. The girders to be bolted to 
 upper side of abacus of column with 1^-inch bolts, and to the 
 entablature with a similar number of bolts. The entablature 
 to be bolted in a like manner to the abacus of column. 
 
 “ There are to be 64 holding-down bolts of 2 \ -inch round 
 iron, each 10 feet long from the underside of nut to the top of 
 cotter on the sqirare end. 
 
 “ All joints of the gasholder to be well coated with red 
 paint both inside and outside, so soon as riveted. The whole 
 of the plates to have, before oxidation shall have taken place, 
 a coat of oil in the following proportions, viz., one part of 
 the best boiled linseed oil, one part of raw linseed oil, and 
 one part of the best turpentine well mixed together. 
 
 u The whole of the plates to be of the best Staffordshire 
 quality, free from sand-holes, cracks, blisters, or any other 
 imperfection. The angle iron to be of S Gr or B B H marks, 
 all rivets and bolts to be made from S C iron. The cast iron 
 to be cold blast, and good, sound, clean castings. 
 
 il The contractor to deliver the gasholder terminated and 
 ready for use within nine months from the date of the 
 Company’s order, under a penalty of i£25 for every week 
 
TELESCOPIC GASHOLDERS. 
 
 203 
 
 that the completion of the gasholder may be deferred beyond 
 that time. 
 
 “ The contractor is required to provide all scaffolding, 
 hoisting tackle, &c., necessary for the completion of the 
 work in a manner satisfactory to the Company’s engineer. 
 
 “ Should the work not be conducted to the satisfaction of 
 the Company’s engineer, and after notice in writing has been 
 given by him to that effect, to the contractor, in the event 
 of no alteration or improvement being made within 24 
 hours of the delivery of such notice, the Company shall have 
 full power to employ any number of men and use materials 
 necessary for the completion of the work by the time speci- 
 fied. All expense or loss incurred by the Company in such 
 proceedings, to be borne by the contractor, and to be 
 deducted from any sum which the Company may have in 
 hand of the amount of his, contract. 
 
 u The contractor to state in his tender the price per ton for 
 wrought and cast iron separately, for which he will construct 
 the gasholder according to this specification. Also a sum 
 for which he will complete the whole without reference to 
 weight, the quality and quantity of iron to be used as herein 
 specified.” 
 
 TELESCOPIC GASHOLDERS. 
 
 When ground is very expensive, telescopic gasholders, 
 which are capable of storing nearly two or three times more 
 gas in a given area than can be done by the single holder 
 just described, are very generally used. 
 
 The telescopic gasholder consists of an ordinary single 
 holder surrounded by a cylinder of sheet-iron, similar to the 
 side of holder, and of about the same height. These are both 
 immersed in the same tank, the depth of which is equal to 
 that of the holder or surrounding cylinder. By an ingenious 
 contrivance, the gas entering causes the holder to rise, and 
 when full lifts with it the cylinder, elongating like the tubes 
 of a telescope, from whence it derives its name. To effect 
 this, on the bottom, extending around the holder, there is an 
 annular cup formed by T iron and plates, represented in 
 section by abccl (fig. 53), which, in rising, is filled with 
 
20 1 TELESCOPIC GASHOLDERS. 
 
 water as shown, and is called the water lute. The surrounding 
 cylinder is about 14 to 18 inches larger in diameter than 
 the holder, and is furnished with a similar annular cup ( f e ), 
 but inverted, called the “ grip,” and when the holder rises 
 to the top, the inverted cup “ grips” or hooks into the water 
 lute of the holder, hermetically sealing the two vessels 
 together, on the same principle as seen in the system of 
 purifiers, where a means of preventing the 
 gas from escaping from the cistern around 
 is adopted. The holder in rising lifts with 
 it the cylindrical vessel or “ lift,” the two 
 reaching a height nearly the double of the 
 depth of the tank. Sometimes there 
 are two cylinders or “ lifts,” when the stor- 
 age is increased nearly three-fold for the 
 same area, as compared with the single 
 holder. 
 
 In order to insure the proper working of 
 the two vessels together, it is usual to fix 
 on the upper edge of the lower cylinder a 
 series of friction-rollers, the periphery of 
 which presses on the inner vessel, serving 
 Fig. 53. to make the motion uniform and to preserve 
 the shape of both cylinders. These friction-rollers are usually 
 from 4 to 6 inches in diameter, about 4 inches broad, and 
 placed 8 or 9 feet apart all round the circumference of the 
 lower vessel. The tank is usually kept full of water, to 
 within an inch of the top. The water lutes vary in depth 
 from 9 to 18 inches, according to circumstances. 
 
 It is very essential in telescopic gasholders that the lifts 
 should be partially counterbalanced by suitable weights and 
 chains, otherwise the pressure is very excessive and irregular, 
 on account of the great weight of water in the lute. The 
 counterbalance weights also assist in the regular and effective 
 working of the lifts ; but in large holders this is not so im- 
 portant as in those of small dimensions. 
 
 But although telescopic gasholders possess advantages 
 where space is difficult to obtain, they should never be fixed 
 where ground is to be had at a moderate price, for in the 
 
TELESCOPIC GASHOLDERS. 
 
 205 
 
 depth of winter, when a sharp frost sets in, and causes the 
 water in the luteg to freeze, they are excessively troublesome, 
 and require constant attention to break the ice of the lutes 
 in order to prevent an accident. Sometimes, through neglect 
 of this precaution, holders have been disabled and rendered 
 useless. 
 
 Another evil with telescopic gasholders is, that when 
 erected near the sea-shore, in a few years the action of the 
 atmosphere destroys the plates in immediate proximity to 
 the lute. It sometimes occurs that the^re is a leak in the 
 lute, and, in consequence, often a great loss of gas is sustained. 
 Where possible single lift holders should always be employed. 
 
 Amongst the largest telescopic gasholders is that of the 
 Imperial Company at Hackney Station, the tank of which 
 is 204 feet diameter, and 41 feet 6 inches deep. The upper lift is 
 199 feet diameter, the outer lift being 201 feet; when full 
 the holder is 80 feet high, and contains 2,500,000 cubic feet of 
 gas. This holder is supported and guarded by 24 cast-iron 
 columns, each about 76 feet long, 3 feet 1 inch diameter at bot- 
 tom, and 2 feet 6 inches at top. Each column is surmounted on 
 a handsome pedestal of about 6 feet high, and weighing five 
 tons. Two ornamental girders, curved to the circle, the one 
 placed midway, the other at top of columns, attach the 
 columns together, and a noble capital on each finishes the 
 column. The cost of tank and holder complete was about 
 £41,000. 
 
 This is perhaps the finest specimen of gas engineering 
 as applied to holders in existence, and I should have been 
 happy to possess further details in connection with its con- 
 struction, so to give them a place here. When full, the gas 
 it contains weighs upwards of 35 tons ; a balloon of the 
 same capacity, filled with ordinary gas, would carry at least 
 500 grown persons. 
 
 The following is a specification of a cast-iron tank and tele- 
 scopic holder, extracted from the “ Journal of Gas Lighting.’* 
 
 “Specification of an Iron Tank and Gasholder . 
 
 “ Cast-iron Tank. — One cast-iron tank of 101 feet 
 diameter, and 22^ feet depth, both inside measure and 
 
206 
 
 TELESCOPIC GASHOLDERS. 
 
 exclusive of the flanges. The flanges to the bottom to be 
 on the inside, the others on the outside, and the whole of 
 them to project 3^ inches at the least. The bottom is to be 
 1 inch thick throughout, excepting the outside row of plates 
 and the row next to it ; the outside row to be 1^ inch thick, 
 and the next row to diminish in thickness from 1^ to 1 inch. 
 The centre plate is to be 1^ inch thick. The first tier of 
 side plates is to be 1J inch, the second 1J, and the third 1^- 
 inch, the fourth 1 inch, and the fifth or top tier 1 inch thick. 
 Each of the side plates is to be of such a width as to allow 
 of 75 in the circumference ; each plate to be 4 feet 6J inches 
 deep ; and each tier of plates is to be numbered in the 
 casting of them, such numbers to be 1, 2, 3, 4, 5, beginning 
 at the bottom tier. 
 
 “ The tank is to be bound together by five wrought-iron 
 hoops, which are to be fixed as shown in the drawings, each 
 hoop to be 5 inches wide and 1^ inch thick. 
 
 “ The tank is to be bolted together with full 1-inch bolts 
 of wrought-iron, not more than 7 inches asunder from centre 
 to centre of each bolt, and properly cemented together with 
 iron cement. A flange column is to be fixed on the centre 
 plate of the tank so as to support the roof of the gasholder 
 when down, and to be of the height and dimensions shown 
 in the drawings. The plates of the tanks, exclusive of the 
 bolts, cement, hoops, and centre column, to weigh tons; 
 and all to be delivered, and the tank to be erected agreeably 
 to drawings, and to the satisfaction of the committee of 
 management of the company or their engineer, for a sum to 
 be fixed, free of any other charge whatsoever, unless the 
 aggregate weight of the plates shall exceed or be less than 
 six tons of the estimate above stated, in which case the price 
 to be charged or deducted is to be after the rate of £ per 
 ton. The company is, however, to pay for nothing beyond 
 the said excess of six tons, and should the deficiency be more 
 than the six tons, then the company is to be allowed from 
 the price to be paid for the tank after the rate of £20 per 
 ton, for such deficiency, whatever it may be. 
 
 “ Each of the plates and castings is to be numbered and 
 marked on the inside with its own weight with white-lead 
 
TELESCOPIC GASHOLDERS. 
 
 207 
 
 paint. The company is to provide good and proper brick 
 or stone foundations, and keep out water ; but the contractor 
 is to find and use the necessary materials for scaffolding, also 
 all pulley blocks and falls, and every other material that may 
 be required in erecting and completing the tank. 
 
 “ The whole of the plates and materials for the tank are 
 to be delivered, and the tank is to be erected complete, on or 
 before the end of thirteen weeks after notice shall have been 
 sent in writing to the contractor from the company, either 
 by hand or by post, that the foundations for the tank are 
 sufficiently prepared for him to begin his work. 
 
 “ Should the tank not be completed as above stated, then 
 the contractor is to be subject to a fine, to be reserved from 
 his account, of £50 per week from the date at which it is 
 agreed that the tank shall be completed ; and should the 
 delay exceed four weeks of the time stipulated, then the 
 company is to be at liberty to employ any other party to 
 complete the tank without being liable to the contractor for 
 payment, either for the plates delivered or such part of the 
 works as he may already have executed. 
 
 “ Hydraulic-room , two 18 -inch Valves , and six 18 -inch 
 Quarter Bends . — One circular hydraulic room with a bottom 
 and top, to be 12 feet diameter and 18 feet deep inside 
 measure, and §ths of an inch thick throughout, with the 
 requisite flanges. The flanges to the bottom are to be on 
 the inside, and all the others on the outside. The whole to 
 be fixed together with f -inch bolts fixed in the same manner 
 as in the tank, and completed according to the plan and 
 dimensions described in the drawings. 
 
 “ Two 18-inch pneumatic lifting-valves, and six 18-inch 
 quarter bends, to be cast agreeably to drawings, and the 
 said valves are to be fitted ready for use. The contractor, 
 on failing to deliver and complete the said hydraulic-room, 
 valves, and bends, to the satisfaction of the committee of 
 management or their engineer, on or before the expiration 
 of the above notice, referring to the tank, is to be subject to 
 a penalty, to be subtracted from his account, of £100 ; and 
 should the delay exceed four weeks of the time stipulated, 
 then the company is to be at liberty to employ any other 
 
208 
 
 TELESCOPIC GASHOLDERS. 
 
 party to complete the said hydraulic-room, valves, and bends, 
 without being liable to the contractor, either for the castings 
 delivered, or for such part of the said hydraulic-room, valves, 
 and bends as he may have already executed. 
 
 a Gasholder . — One circular gasholder to be made of the 
 best plate and English iron, upon the telescope principle, to 
 the above-mentioned tank. It is to be in two parts, and 
 correspond in diameter and height with the dimensions given 
 in the drawings. The roof and top tier of side platen of the 
 gasholder are to be of No. 11 wire gauge, and all the other 
 side plates are to be of No. 12 wire gauge. Each part is to 
 be 22 feet deep, and is to have a hydraulic joint 15 inches 
 deep and 8 inches wide of No. 10 wire gauge, one part of 
 the joint to be connected with the top of the bottom part. 
 The top edge of the cup, and the bottom edge of the dip 
 are to be bound by half-round iron, 2 inches by 1 inch thick. 
 The roof of the gasholder is to be a dome roof, supported 
 within in the usual way, with sufficient wrought-iron frame- 
 work, and twenty -four trusses, and the requisite intermediate 
 rafter bars, strutted as shown in the drawings. The side of 
 the upper part is to have twelve vertical truss bars, equi- 
 distance from each other in the circumference inside. The 
 lower part is to have twenty vertical plates of flat iron, 3 
 inches by §ths of an inch, reaching from the top to the 
 bottom on the inside, with the requisite intermediate 
 bars, strutted as shown in the drawings. The gasholder 
 is to have twenty-four cast-iron guide -pulleys and car- 
 riages, twelve of which are to be attached to the upper 
 part and twelve to the top of the bottom part, to work upon 
 guide-rods, and also twelve friction rollers are to be attached 
 to the dip of the hydraulic cup on the top of the lower part 
 of the gasholder, to work between its upper and lower parts; 
 thirty -six friction rollers are also to be attached to the bottom 
 edge of the lower part, to work between it and the tank, all 
 as shown in the drawings. The whole to be of the requisite 
 dimensions to suit their respective places, and the rim of the 
 lower part is to be strengthened with a double wrought-iron 
 curb of angle-iron 4 inches by 1 inch at the root, and a ring 
 of bar-iron 4 inches by 1 inch in thickness. The sheets of 
 
TELESCOPIC GASHOLDERS. 
 
 209 
 
 the gasholder are not to exceed 4 feet in length by 2 feet 2 
 inches in height ; and the rivets are not to be less than \ 
 inch in diameter, nor more than 1 inch asunder from centre 
 to centre, their heads showing on the outside. Twelve eye- 
 bolts and shackles are to be attached to the upper edge of 
 each gasholder at equal distances from each other. 
 
 “ The said gasholder, &c., are to be delivered and executed 
 complete according to drawings, and so as to apply to the 
 said tank, and to the columns and frame after mentioned, and 
 to the satisfaction of the committee of management or their 
 engineer. The contractor is to provide himself with and use 
 the pulley blocks and falls, and every other necessary material 
 for constructing the scaffolding, which he is to erect at his 
 own expense. 
 
 “ The materials of the gasholder, including friction 
 rollers, pulleys, &c., &c., an<j all their appendages, are to be 
 delivered, and the whole erected and fitted complete, on or 
 before the end of thirteen weeks after notice shall have 
 been given as above stated in reference to the tank, that the 
 said tank is sufficiently completed to enable the contractor 
 to commence the building of the said gasholder, &c., &c., 
 for a sum to be fixed free of any other charge, such sum to 
 include the price of the columns and frame after mentioned. 
 
 “ Should the said gasholder, with all its appendages, and 
 also the columns and frame after mentioned, not be completed 
 as above stated, then the contractor is to be subject to a fine 
 of <£50 per week, to be reserved from his account, from the 
 date of the period wherein it may be agreed that they shall 
 be completed ; and should the delay exceed four weeks of 
 the time stipulated, then the company is to be at liberty to 
 employ any other party to complete the said works, without 
 being at all liable to the contractor for payment for any part 
 of the works which he may have already executed. 
 
 “ Columns and Frame , — The said gasholder is to have 
 twelve cast-iron columns, and a cast-iron frame to connect 
 them together at equal distances from each other in the 
 circumference, as shown in the drawings. 
 
 “ Each column is to be composed of four lengths, and 
 when erected to be, including the said frame, about 62^ feet 
 
210 
 
 TELESCOPIC GASHOLDERS. 
 
 high, from the top of the foundations to the top of the frame, 
 so that the whole frame shall be arranged to one level. 
 The columns to taper from 24 inches diameter at their bases 
 to 16 inches at their tops, and be 1|- inch thick at bottom, 
 tapering to 1 inch at top. The metal of the frame is to be 
 1 inch thick throughout. Each casting is to be numbered 
 and marked with its weight with white-lead paint. 
 
 “ Twelve wrought-iron guide-rods of railroad iron, 
 according to drawings, and with the requisite chairs, to be 
 fixed and applied one to each column, and reach from the top 
 of the tank to the under side of the frame ; and each column 
 is to have a foundation plate of cast-iron 6-^- feet long, 4 feet 
 wide, and 2 inches thick, and four wrought-iron holding- 
 down pins of 2 inches square iron, 10 feet long each, and to 
 be fixed with the necessary lead, as shown in the drawings. 
 
 “ The columns are to be bound together with a cast-iron 
 frame as mentioned, which is to be composed of twenty-four 
 girders, to be connected in the circumference of the tank 
 from column to column at top, and each girder is to be fitted 
 to its respective columns and to its respective girders. The 
 whole to be properly chipped and secured together with 
 proper screwed bolts, nuts, collars, &c., of wrought iron, 
 cemented together with iron cement. The plan of the frame, 
 and also for the elevation section, bearings, and mode of 
 connecting the columns, guide-rods, and girders, to be accor- 
 ding to drawings. 
 
 “ The said columns and frame, with their appendages, are 
 to be delivered and erected complete, so as to apply to the 
 said gasholder and tank, and to the satisfaction of the com- 
 mittee of management or their engineer, and within the time 
 and under the conditions named in respect to the gasholder." 
 
 The earliest gasholders were made in the form of cubes 
 and other rectangular figures, but there were disadvantages 
 in this form, independently in the waste of material required 
 to construct a rectangular figure as compared with that re- 
 quired for a circular figure of the same capacity. The 
 corners and angles of the square figures were also found to 
 require bracing, and other precautions were necessary in 
 
TELESCOPIC GASHOLDERS. 
 
 211 
 
 order to render the resistance uniform. Wooden tanks were 
 also at one time made for the lifting parts of the gasholder 
 to work in, but this was at a time when gasholders scarcely 
 exceeded in size some of the large vats or backs in use at 
 the great porter breweries. The construction of these 
 wooden tanks was in fact intrusted to the back-makers, who 
 used to guarantee the duration of the vessel for some period 
 of time agreed on. They were, in consequence, generally 
 constructed in a substantial manner, but it is evident that 
 the rapid increase which took place in the size of gasholders 
 required the adoption of a different material from wood. 
 When a deputation from the Royal Society, with Sir Joseph 
 Banks at its head, visited the Gas-Works of the Chartered 
 Company in Westminster about the year 1814, they strongly 
 recommended Government to restrict the Company from con- 
 structing gasholders exceeding 6,000 feet in capacity, to be 
 confined in very strong buildings. When Mr. Clegg pub- 
 lished his work in 1841, he says, “ Gasholders are now 
 constructed to contain 250,000 feet.” Since then the capacity 
 of gasholders has been increased tenfold, and there is 
 reason to believe that in the course of a few years even these 
 colossal dimensions will be surpassed. 
 
 In the department of gas engineering, there are several 
 manufacturing firms of great eminence, who devote them- 
 Belves chiefly or wholly to the manufacture of gasholders, 
 and the concentrated attention which the subject thus 
 receives, has undoubtedly led to very favourable results. 
 An engineer, in erecting a works, may receive tenders for 
 his gasholders from a number of well-qualified contractors, 
 who have each their own method of construction, and may, 
 if he chooses, be saved much of the trouble and responsibility 
 of designing these vessels himself. 
 
212 
 
 ON THE EXHAUSTER. 
 
 CHAPTER XIV. 
 
 ON THE EXHAUSTER. 
 
 Referring again to the composition of gas, which is principally 
 hydrogen and carbon, the first — to use the term of the late 
 Mr. A. Wright* — being the solvent of the latter : when 
 burned, the hydrogen is consumed at the lower part of the 
 flame, leaving the carbon in a state of solid, to combine with 
 the oxygen of the atmosphere, and ignite, and according 
 to the degree of temperature it attains, so will be the amount 
 of light produced from it. 
 
 There are various ways to prove that the carbon of gas 
 assumes the solid state, and perhaps the most forcible is to 
 call the reader’s attention to the facility with which lamp-black 
 is produced from gas when burned in a close vessel with an 
 insufficient supply of air ; by these means, and careful mani- 
 pulation, as much as 17 lbs. or 18 lbs. of lamp-black may be 
 produced from 1,000 feet of gas. It is obvious, therefore, this 
 weight must arise merely from the solid obtained from the gas. 
 
 As already explained, when gas is subjected to a high 
 temperature and great pressure, an incrustation of carbon is 
 deposited in the retorts, this being really the same nature of 
 material as the lamp-black, but more compact and solid. 
 Thus there are two ways of obtaining the carbon in a solid 
 state from the gas — the one in the act of burning, the other 
 when producing it. 
 
 During many years the action just mentioned was not 
 understood, and engineers attached little importance thereto, 
 considering it merely incidental to the carbonisation of coal ; 
 but we now know this to arise from the decomposition of the 
 hydrocarbons, or olefiant gas, and the deposit of a large 
 portion of the very richest ingredients of the gas in a solid 
 state in the retort, instead of passing to the holder to pro- 
 duce light. 
 
 As already stated, it is not only in this deterioration of the 
 
 * In the first volume of the “ Journal of Gas Lighting ” there is a very 
 excellent article on the Theory and Economy of Artificial Light — to which 
 reference is made. 
 
ON THE EXHAUSTER. 
 
 213 
 
 illuminating power of the gas where the loss exists, for the 
 carbonaceous deposit is a very bad conductor of heat, it 
 occupies a large space in the retorts, thereby diminishing 
 the weight of the charge, and its presence undoubtedly re- 
 duces the value of the coke when produced therewith. Thus, 
 by this deposit, the gas is deteriorated in value, and more 
 retorts are necessary than would otherwise be requisite, so 
 augmenting the capital and the fuel account ; wear and tear 
 and labour are also materially increased. 
 
 Mr. John Grafton was the first to understand these diffi- 
 culties, and to endeavour to provide a remedy for them. 
 That gentleman, suspecting the real cause of the deposit, 
 entered into a series of experiments, by increasing the 
 pressure in the retorts until it became equal to a column of 
 14 inches of water, whereby, in a single week, an incrustation 
 of 1 inch in thickness was produced ; and at the expiration of 
 two months this was so much increased as nearly to occupy 
 one-fourth of the retort. The result of the experiment being 
 that in carbonising 67 tons of Wallsend coal, 10 cwt. 24 lbs. 
 of carbon was- deposited as incrustation in the retort, being, 
 in fact, that weight of the. very richest portion of the gas lost. 
 
 Mr. Grafton afterwards carried out some experiments 
 under different circumstances, by withdrawing or exhausting 
 the gas immediately produced, there being in this case only 
 a pressure of half an inch, or that dip of the fluid in the 
 hydraulic main ; when, with the same description of coal, 
 and the same heat as before used, at the end of four months 
 scarcely any deposit took place. The correctness of these 
 experiments are now fully borne out by every day practice. 
 
 The earliest form of machine or exhauster used for with- 
 drawing or pumping the gas from the retorts as produced, 
 was a kind of meter wheel ; the gas entered this by a hollow 
 shaft, and was expelled at the periphery. This wheel being 
 caused to revolve by steam or other power exhausted the 
 gas from the retorts ; but, like many other simple yet great 
 ideas, it required a long time before the merits of the 
 invention were fully understood and appreciated. 
 
 There are various kinds of exhausters now employed, and 
 probably the instrument most universally adopted is that 
 
214 
 
 ON THE EXHAUSTER, 
 
 manufactured by Mr. Beal, of London. This consists of a 
 cast-iron cylindrical vessel closed at both ends. At one end a 
 shaft (which carries the pulley for the driving belt) passes 
 through a stuffing box. This shaft is placed eccentrically to 
 the outer case, and attached to it is a cylinder of the same 
 length as the case, but considerably smaller in diameter. In 
 this smaller cylinder there are two sliding plates which have 
 the effect of pistons, and when the shaft revolves, these pistons 
 exhaust the gas from the retorts and expel it to the holder. 
 
 Mr. Jones, of Birmingham, is the manufacturer of a very 
 ingenious instrument for exhausting gas, many of which 
 have been in use several years without requiring repair. 
 
 The exhauster which recommends itself for little friction, 
 is that used by Mr. Metliven, of the Imperial Gas Company, 
 and consists of three gasholders, working in separate and 
 distinct tanks, which are nearly filled with tar. These are 
 attached to three distinct cranks on a shaft, placed at equal 
 angles to each other, so that the action may be uniform and 
 regular. Each holder has a rod which works through a 
 stuffing box connected to its corresponding crank above ; 
 there are also suitable pipes and clack valves for the ingress 
 and egress to the interior and exterior of each holder. The 
 shaft being put in motion by steam or other power, the 
 cranks raise and depress the holders, which, by the interven- 
 tion of the tar, pump or exhaust the gas. 
 
 Another form of exhauster is very similar to the high- 
 pressure steam-engine, having piston, cylinder, and valves ; 
 these are made either as single engine or double engine. 
 That made by Mr. Anderson is of the simplest kind, the 
 cylinder of exhauster and engine driving it, both being on 
 the same foundation plate, and their respective pistons 
 connected by different cranks to the same axle and fly-wheel. 
 The cylinder of the exhauster is about eight times the 
 capacity of that of the engine, and, in consequence, for every 
 foot of steam employed, eight feet of gas are exhausted. 
 
 In employing these instruments, great care is requisite to 
 avoid undue exhaustion ; should this occur, then atmospheric 
 air from the pipes, or carbonic acid from the furnaces, would be 
 drawn into the holder and intermix with the gas, causing a 
 
ON THE EXHAUSTER. 
 
 215 
 
 serious prejudice. According to Mr. Lewis Thompson, one 
 per cent, of carbonic acid intermixed with gas reduces its 
 illuminating power from 8 to 10 per cent.; and, according to 
 Messrs. Audouin and Berard, six parts of aiiHntermixed with 
 94 parts of gas, reduce the illuminating p'ower to one half of 
 the light of the same gas when pure : and when 20 parts of air 
 are intermixed with 80 parts of gas, the illuminating power of 
 the gas is entirely destroyed. Therefore it is of the utmost 
 importance to avoid the possibility of intermixing either air 
 or carbonic acid with the gas by excessive exhaustion. 
 
 The seal on the dip pipes should not be less than half an 
 inch, nor more than one inch, and care should be taken that 
 no escape exists on the line of pipes between the exhauster 
 and hydraulic main. 
 
 Some engineers prefer placing this instrument between the 
 condenser and scrubber ; but as the latter apparatus deprives 
 the gas of a large quantity of tar that would tend to clog 
 the exhauster, perhaps a better position for it is after the 
 scrubber, and before the purifiers. 
 
 The pressure guage of the exhauster should always be 
 communicated directly with the hydraulic main, so that the 
 pressure therein may be ascertained with the most rigid 
 accuracy. As often practised, the guage only indicates the 
 pressure at a considerable distance from the retorts, so that 
 a partial stoppage in the main, or variation in the production, 
 is likely to cause an error. 
 
 In the very earliest days of gas lighting, when the meter 
 was first used, it was employed as a motive power, the gas 
 as produced causing the wheel to revolve, the axis of which 
 protruded through a stuffing box, and gave motion to the 
 purifying apparatus, thus reversing entirely the present and 
 correct method of working. 
 
 A great impediment to the employment of an exhauster, 
 in small works, has been the care necessary with a steam 
 boiler, and the chances of danger therefrom. This, however, 
 no longer exists, for gas engines are now made which require 
 no boiler, nor is there the least apprehension of danger, so 
 that any works requiring only half a horse power, can 
 employ it with all possible security. 
 
2l6 
 
 ON GAS-METERS. 
 
 CHAPTER XV. 
 
 ON GAS-METERS*. MR. Clegg’s METER — SIR WILLIAM CON- 
 
 GREVE’s METER THE WET METER MOTIVE POWER 
 
 METER STATION METER — THE DRY METER. 
 
 The whole history of the gas-meter is one of great philo- 
 sophical interest. At a very early period of gas-lights, it 
 became an object of great importance, both to the manu- 
 facturers and consumers of gas, to possess the means of 
 measuring the consumption, in order that a proper adjust- 
 ment of charges might be made. The system of charging 
 the consumer an annual rent for a certain number of burners, 
 on the supposition that these consumed a given quantity per 
 hour, and were used daily for a certain number of hours, 
 was found to be exceedingly vague and unsatisfactory. It 
 obviously afforded the means of so much fraud, that gas 
 companies were necessarily obliged to leave an ample margin 
 to cover the contingencies of dishonest burning, so that the 
 conscientious consumer was charged heavily to make up for 
 the delinquencies of a large class who were not so scrupulous. 
 Hence it appears perfectly natural that the great array of 
 mechanical talent, which has been from the first so active in 
 the improvement of all kinds of gas machinery, should have 
 directed unwearied attention to the contrivance of apparatus 
 for ascertaining with accuracy the quantity of gas burnt by 
 each consumer. 
 
 The merit and honour of having invented and constructed 
 the first gas-meter is due to the late Samuel Clegg, who in 
 1815 patented “ a gauge or rotative gas-meter. ,, This 
 instrument, although very ingenious, was far from being a 
 practical machine, and afterwards underwent various modifi- 
 cations, but never attained that degree of perfection so 
 essential for its general adoption. 
 
 About 1817 the very ingenious Mr. John Malam invented 
 another description of instrument for measuring gas, which 
 undoubtedly led to the construction of the meter since so 
 universally employed, and so justly appreciated. On the oc- 
 casion of this meter being presented by Mr. Malam to the 
 
ON GAS-METERS. 
 
 217 
 
 notice of the Society of Arts, Mr. Clegg asserted that it had 
 been copied from him, which serious charge was investigated 
 by a committee of the society, who ultimately, after great 
 deliberation, gave their verdict in favour of Mr. Malam, by 
 awarding him their gold medal for his “ invention of a gas- 
 meter, new, ingenious, superior to all others, and likely to be 
 of great benefit to the public. , ’ The extraordinary originality 
 of invention since displayed by Mr. Malam has confirmed 
 the decision of the Society of Arts, whilst an admission has 
 been made, in the treatise on coal gas written by the son of 
 Mr. Clegg, under the sanction of his father, that Mr. Malam 
 introduced the “ hollow cover,” so removing all doubt on the 
 matter. 
 
 Among the first instruments proposed for the indication of 
 the quantity of gas passing, was that invented by Sir William 
 Congreve. This consisted of a kind of timepiece attached 
 to the main cock, so that, in the act of turning this on, a 
 pendulum was set in motion, which marked on the dial the 
 time it was open ; and when the supply was shut off, this 
 pendulum was stopped. By this means the number of hours 
 the gas had been burning was ascertained in a tolerably 
 accurate manner, but, of course, could not be even an 
 approximation to the quantity ; however, it was far superior 
 to the general system of contract, where the gas was left 
 entirely at the mercy of the consumer. 
 
 These instruments, at one period, were much used in 
 France, the accounts being made out according to the 
 number of hours indicated by the instrument, multiplied by 
 the number of lights on the premises ; and were called 
 compteurs a Vheure , or hour meters. 
 
 There are two kinds of gas-meters now in use, the “wet” 
 and the “ dry ” meter ; the former is so called because it 
 requires a liquid, as water, to render it effective ; the latter 
 derives its name from the absence of such liquid, it being 
 complete in itself. 
 
 Each description of instrument has its advocates ; for 
 whilst some gas companies countenance only the w r et, others 
 will use but the dry meter. Whilst engineers greatly inter- 
 ested in gas companies prefer the one, there are others 
 
 L 
 
218 
 
 ON GAS-METERS. 
 
 similarly situated who have directly the opposite opinion ; 
 therefore, with those different views, it cannot be expected 
 that a definite decision of their respective merits will be 
 given here : nevertheless the progress made by the dry 
 meter during the last twenty years must be admitted as a 
 strong argument in its favour. 
 
 The measurement of gas by meter is as simple, and as 
 positive, as the measurement of liquids by the most ordinary 
 operation ; and the volume of the first is capable of being 
 ascertained by the meter with the same precision that liquids 
 are defined by quarts, gallons, &c. There is, however, a very 
 important difference, inasmuch as with liquids, when ordi- 
 narily measured, any interruption in the delivery is not 
 material, but with gas the supply must be exact and con- 
 tinuous. The slightest obstruction in the instrument would 
 cause a disagreeable interruption in the supply of gas ; 
 consequently the lights would vary, or perhaps be altogether 
 extinguished. Therefore, in addition to measuring, the 
 meter must be self-acting ; and, that the supply of gas may 
 be continuous and perfectly uniform, it must be remarkably 
 delicate in its construction. 
 
 Let us conceive that the supply of a liquid, as water, ale, 
 wine, &c., in being measured, required to be delivered with 
 the same uniformity as gas ; and for the purpose we may 
 imagine a rude self-acting machine, as shown in Fig. 54. 
 Here, it will be observed, there are four vessels of known 
 capacity, attached, at right angles to each other, to axle a, 
 with which they revolve. The axle is supported by, and 
 revolves freely in, suitable bearings, which, for simplicity, are 
 not shown. The vessels are filled successively by hand or 
 otherwise, there being suitable mechanical means to prevent 
 them moving until each in succession is quite full. As seen 
 in sketch, vessel No. 1 is being supplied with the liquid to 
 be measured ; and No. 4, which has been filled, is emptying 
 itself. When No. 1 is full, by the action of the weight of 
 the liquid contained therein, it suddenly descends, bringing 
 No. 2 in the position to be filled ; at the same time vessel 
 No. 1 is emptied ; then No. 2, being filled, descends, bringing 
 vessel No. 3 in position to be filled ; and so on continuously, 
 
ON GAS-METERS. 
 
 219 
 
 causing the vessels to revolve with the axle in the direction 
 of the arrows, so long as there is a supply of liquid. 
 
 We will suppose each of these vessels to contain one quart, 
 so that each time they revolve, four quarts or one gallon of 
 liquid must be received and delivered by them ; and in order 
 
 Fig. 51. 
 
 to avoid the necessity of continuously counting each revolu- 
 tion of the measures, or, in other words, the quantity re- 
 ceived and delivered, we make it a self-recording instru- 
 ment. 
 
 This would be done by fixing on the axle a suitable screw 
 or worm, working into a toothed wheel in communication 
 with a dial : thus, if the wheel had twenty teeth, the measures 
 in revolving twenty times would cause its axle to revolve 
 once, and indicate 20 gallons ; and the motion being further 
 communicated to an index by suitable wheel-work, the quan- 
 tity passing would be recorded with much greater accuracy 
 than any human supervision could attain. 
 
 This supposed instrument is based on precisely the same 
 principle as the gas-meter, for in the latter there are four 
 measuring vessels attached to and revolving with a shaft, 
 which are filled with gas and emptied in succession, and the 
 number of times they revolve, or the quantity of gas received 
 
220 
 
 ON GAS-METERS. 
 
 from the company and delivered to the consumer, is indicated 
 on the dial of index. 
 
 The annexed figure 55 represents a section of a gas-meter : 
 mmm is the outer case ; ekkk the revolving measuring 
 wheel attached to axle a, which works in suitable bearings 
 shown in Fig. 56. The wheel is divided by the partition 
 plates, pppp (which are slightly inclined, so as to offer 
 little resistance), into four distinct measuring compartments 
 or vessels, Nos. 1, 2, 3, and 4. The wheel is immersed in 
 water, contained in the case, to some distance above the 
 
 centre, as shown by the dotted lines, and by a very ingenious 
 contrivance the gas always enters the vessels in succession 
 at the side b, and by its force presses between the surface of 
 the water and the side of partition p, as in the case of the 
 gasholder already described, thereby causing the vessels to be 
 
ON GAS-METERS. 
 
 221 
 
 filled ; the wheel to revolve in the direction of the arrows ; 
 and the gas to be simultaneously expelled from the vessel at 
 the side c ; and so on continuously as long as the gas passes. 
 When the chambers arrive at the centre, as No. 1, they are 
 filled with gas, and in that position neither receive nor 
 deliver, but so soon as they pass over the centre, as the 
 wheel revolves, the gas passes by the outlet to the burners. 
 
 The similarity between the liquid measure just described, 
 and the gas-meter, must be evident. In the first case the 
 weight of the liquid when filling causes the vessels to revolve 
 and empty themselves ; in the other, it is the force of the 
 gas which causes it to fill each vessel in succession, ex- 
 pelling that existing in others on the opposite side, and so 
 causing the series of measuring chambers, or as called, the 
 wheel, to revolve, being, in fact, four gasholders attached 
 to the same axle, which are, filled and emptied in rotation. 
 
 The measuring wheels of gas-meters are of course made 
 with great accuracy, and vary in size according to the num- 
 ber of lights they are destined to supply. Their capacity is 
 generally calculated so that wdien the maximum of lights is 
 burning, each light consuming at the rate of 5 feet per 
 hour, the w 7 heel will make 100 revolutions per hour. Thus 
 a meter for ten lights is estimated to deliver 50 feet per hour, 
 therefore, the contents of each revolution of the w 7 heel is 
 equal to half a cubic foot, and it follows that this w^ould have 
 to be filled and emptied, or revolve, tw 7 o hundred times be- 
 fore 100 feet w’ould be indicated on the dial of the index : 
 by this means the meter registers with unerring exactitude 
 during many years, until rendered useless from decay. 
 
 The train of w T heel-work giving motion to the hands on 
 the dials is very simple, each pinion working into a wheel 
 containing ten times as many teeth as itself : the ordinary 
 dials register hundreds, thousands, and tens of thousands, the 
 whole of w 7 hich are actually indicated, while the parts of 
 100 feet are read by estimation, and the units of feet are in- 
 dicated on a revolving cylinder in the index-box of meter. 
 
 Fig. 56 is a cross section of a meter, k k is the wheel or 
 series of measuring vessels enclosed in the case, supported 
 by the axle working in suitable bearings. There is a rectan- 
 
222 
 
 ON GAS-METERS. 
 
 gular box attached to the front of case ; on this is a pipe, a, 
 for the admission of the gas ; the egress pipe is marked i ; 
 the meter being charged with water to the line h h. 
 
 Fig. 57 is a front view, showing the details of the contents 
 of square box. f is a float similar to that used in water 
 cisterns. On the top of this is attached a valve connected 
 with a lever ; and when there is an insufficiency of water 
 in the meter, the float descends, closes the valve, and so 
 obstructs the passage of the gas until the meter has the 
 ^ proper quantity of water. There is a pipe, c, the top of 
 
 which is level with the water line ; and any excess of water 
 passes down this into the waste-box, d, from whence it can 
 be withdrawn from the pipe e by the screw. 
 
 The meter being charged with water ready for use, the 
 gas flows through the pipe a, Fig. 56, the valve being open, 
 
ON GAS-METERS. 
 
 223 
 
 into a square box, and passes by the bent tube l, in the direction 
 c f the arrows, into the hollow disc or wheel cover, where are 
 situated the entrances to the four measuring vessels, the 
 passages for the egress of the gas being at the other end, or 
 back, of wheel. 
 
 Meters, when worked beyond a certain speed, require con- 
 siderably more pressure to drive them. Under these circum- 
 stances they indicate slightly against the company, and have 
 a tendency to inconvenience the consumer by suddenly extin- 
 
 guishing the lights, through the float falling and shutting the 
 valve ; therefore a meter ought never to supply much more 
 gas than the quantity for which it is destined. The number 
 of burners is not essential ; it is the quantity of gas which 
 passes : thus, the meter for ten lights, or 50 feet per hour, 
 w ill be able to deliver gas for twenty burners, each consuming 
 
224 
 
 ON GAS-METERS. 
 
 2\ feet per hour, or any number in the same proportion ; 
 and, as shown, only indicates the volume of the gas passed. 
 
 On referring to Fig. 55 it will be observed that the part 
 of the measuring vessel nearest the axis is defined by the 
 height of the liquid ; therefore by the addition of water the 
 capacity of the chambers must be diminished, and by its 
 abstraction they would be increased, the first contingency 
 being detrimental to the interests of the consumer, the latter 
 to the prejudice of the company; and if no remedy existed for 
 these, the gas-meter would be a very imperfect instrument. 
 
 In order to prevent the gas passing when there is an 
 insufficiency of water, the meter is provided with the float 
 already described, which shuts off the supply whenever the 
 water is below its proper level, thus protecting the interest of 
 the company ; and any excess of water, which would be 
 detrimental to the consumer, falls down the pipe c into the 
 waste-box d. By these simple means the interests of both 
 buyer and seller are secured. 
 
 Formerly the degree of accuracy now attained in ensuring 
 the proper water level, and the rigidly correct registration of 
 the meter, was not considered. Meters at one time were 
 made in such a manner that, although perfectly correct at the 
 proper water line, they could be caused to vary materially 
 either against the company or consumer, by the subtraction 
 or addition of water ; but as the instrument was in the 
 custody of the latter, he was always in the position to 
 prevent an excess of water remaining in the meter, and, if 
 so disposed, he could take advantage of the facilities afforded 
 to abstract water ; therefore this evil was not favourable to 
 gas companies. 
 
 A few years ago the attention of the public was called to 
 this defect in the gas-meter ; and, the worst intentions being 
 assumed, considerable agitation existed on the subject, when 
 the intervention of government became necessary ; and, 
 accordingly, an Act of Parliament was passed, forbidding 
 the sale of all meters which by any means could be made to 
 vary more than two or three per cent, from the correct 
 standard, which range allowed for a certain amount of 
 evaporation of water from the meter. 
 
ON GAS-METERS. 
 
 225 
 
 Subsequently some manufacturers surpassed the parlia- 
 mentary conditions, by making gas-meters even more perfect 
 than the Act required, by constructing them to maintain an 
 unvarying water line, so as to measure strictly accurate 
 under all circumstances ; which instruments are called com- 
 pensating meters, signifying that they compensate for any 
 loss of water that may take place. Fig. 58 is a front view 
 of a meter of this class, as manufactured by the firm of 
 A. Wright, Westminster. In the front part of square box 
 
 Fig. 58. 
 
 there is a separate reservoir, containing water to supply any 
 deficiency in the meter ; and all excess of water passes to 
 this reservoir. The supply is effected by the shaft of the 
 toothed wheel, in revolving, giving motion to the scoop a, 
 which lifts a quantity of water from the reservoir, and 
 conveys it to the interior of the meter, so maintaining the 
 surface of the water continually at the same level ; and. in 
 consequence, the measurement is strictly correct. 
 
 Another means of obtaining the same result is by the 
 beautiful invention of Messrs. Sanders and Donovan, re- 
 markable for its simplicity and ingenuity, and based on truly 
 scientific principles. 
 
 L 3 
 
226 
 
 ON GAS-METERS. 
 
 Fig. 59 represents a meter with this improvement. B is 
 the outer case on which is fixed a circular case, which 
 replaces the square box already mentioned. A is an air- 
 tight vessel, in reality a float fixed on axle x, working 
 freely in its bearing a. so that it can make nearly half a revo- 
 lution. When there is an insufficiency of water the float 
 hangs in the position shown by the dotted lines, and the 
 plug b closes the valve attached to box c. 
 
 The meter having a proper supply of water, the float 
 slightly changes its position and opens the valve for the 
 
 Fig. 59. 
 
 passage of the gas ; now, if more water be added to allow 
 for evaporation, the float gradually rises until assuming tin 
 position in cut, the level of the water in the meter remaining 
 without the least variation. 
 
STATION METER. 
 
 227 
 
 In the course of time, any evaporation that may take 
 place is compensated by the float descending in the direction 
 of the arrow, and by means of its bulk maintains the level 
 of water always at the same height, and when it can no 
 longer act, shuts the passage of the gas. 
 
 The action of this compensator is a combination of several 
 principles of mechanics, and accomplishes the desired effect 
 without the aid of any motive power from the meter. These 
 instruments are manufactured by the Gas Meter Company, 
 Kingsland Hoad, London. 
 
 Meters are also constructed, where the measuring drum is 
 caused to float, and others have proposed to float the entire 
 meter and case in a separate vessel, but the last has not 
 come into use. 
 
 To avoid as much as possible the loss by leakage, it is 
 always the interest of gas companies to have the pressure 
 in the mains as low as possible ; and in small towns, where 
 there is no consumption during the day, a pressure of one 
 tenth, in the lowest part of the district, will be sufficient to 
 keep the air from entering. But there are cases where, in 
 order to supply one or two consumers, the pressure has to 
 be kept on continuously, so occasioning great loss by leakage. 
 This is avoided by attaching a motive power meter to the 
 premises requiring gas, when, if the pressure in the main 
 be only one tenth, it can be increased by this instrument so 
 as to give an abundant supply where requisite. 
 
 STATION METER. 
 
 The station meter is an instrument employed at all well- 
 regulated gas-works, to record the quantity of gas produced, 
 and is as essential to the strict economy of an establishment 
 as the stock -book is to the merchant. This differs from the 
 consumer’s meter in some particulars, but is in principle 
 the same. The difference consists in the exterior form, those 
 of small dimensions being cylindrical, whilst the larger 
 descriptions are generally made square, and often very 
 ornamental. The pipes for entrance and exit of gas are at 
 the back, the dial of the index is in the centre in front, the 
 
228 
 
 STATION METER. 
 
 float is dispensed with, and a glass gauge indicates the level 
 of water ; in other respects it is identical with the other 
 already described. The index of a station meter, according 
 to its capacity, contains six, seven, or more dials, the hands 
 of which register in succession from hundreds, up to tens or 
 hundreds of millions of cubic feet. In large meters, attached 
 
 to the index is a clock, the hour-hand of which is connected 
 with a rod carrying a spring pencil. Immediately under the 
 clock dial, and in the centre of index, is a disc, which revolves 
 according to the daily production, and on this disc is fixed a 
 sheet of paper, having divisions on its outer circle cor- 
 responding with the maximum daily production, which it is 
 intended to indicate. The pencil before mentioned receiving 
 
THE DRY METER. 
 
 229 
 
 motion from the hour-hand, by the action of the disc revolving, 
 makes a curved mark on the paper, so indicating the number 
 of hundreds or thousands of feet of gas produced per hour. 
 An inspection of the paper so marked shows at a glance any 
 irregularity that may have occurred in the production of gas, 
 affording the superintendent a good check on the workmen 
 during his absence. 
 
 Fig. 60 represents an elevation of a Station Meter, by 
 the firm of A. Wright, Westminster, capable of measuring 
 one hundred thousand feet per hour, or two millions four 
 hundred thousand feet per diem. The measuring wheel of 
 this meter delivers 1,000 feet at each revolution. Messrs. 
 Wm. Parkinson and Co., successors of the late S. Crosley, 
 are also extensive and accredited manufacturers of station and 
 consumers’ meters, regulators, and other instruments of pre- 
 cision employed in the manufacture and distribution of gas. 
 
 THE DRY METER. 
 
 This instrument has undoubtedly some important advan- 
 tages ; requiring no water for its action, there is no possibility 
 of the passage of the gas being obstructed by frost, nor 
 are the pipes liable to be stopped by the vapour of the water 
 condensing in them. The dry meter does not demand a 
 periodical attention, like the other, either to add or abstract 
 water, nor is there the probability of the lights being sud- 
 denly extinguished from an insufficiency of water. 
 
 Such was the prejudice existing against the use of dry 
 meters twenty-two years ago, that very few gas companies 
 could be induced even to try them. It was feared that the 
 flexible material entering into their composition would speedily 
 decay, whereas experience has demonstrated this, when pro- 
 perly prepared, to be the most durable part of the instru- 
 ment. The dry meter was then considered of such extreme 
 delicacy in its construction, that its durability must of neces- 
 sity be very limited ; however, experience and time have 
 gradually dispelled these notions, and the dry meter has now 
 become a formidable rival to the other, and as a proof of 
 their general adoption at the present day, nearly every wet 
 meter manufacturer constructs them. They are largely em- 
 
230 
 
 THE DRY METER. 
 
 ployed by all the London and provincial gas companies in 
 the United Kingdom ; they are used almost exclusively in 
 the United States ; and are now becoming general on the 
 Continent. 
 
 The first record of a dry meter is the patent of Mr. John 
 Malam, in the year 1820, in which he adapted a series of 
 bellows combined together on to one common shaft ; but the 
 plan was not practicable, nor was it ever carried into effect. 
 
 The principle of the dry meter will be best understood by 
 referring to the action of the common bellows. When the 
 upper leaf of this well-known domestic implement is raised, 
 an exhausting power is produced in the interior of the 
 bellows, whereupon the external air raises the valve in the 
 lower leaf, and enters. When the upper leaf is now de- 
 pressed, the valve is immediately closed and the air expelled 
 through the nozzle of the bellows. If we now conceive the 
 upper leaf to be attached to clock-work, so as to register the 
 number of times which the bellows has been thus filled and 
 emptied, it is evident that, knowing the capacity of the 
 bellows when expanded, we obtain the means of measuring 
 the quantity of air which has passed in and out. 
 
 Now, in the dry meter, gas is measured by the alternate 
 expansion and contraction of chambers, which may very aptly 
 be compared to the expanding and contracting chamber of 
 the bellows. These chambers vary in shape in different 
 kinds of meters. For example, in Defries’ meter the vessel, 
 or outer case, is divided into three distinct compartments, 
 each of which is subdivided by a square flexible leather 
 partition, strengthened by tin plates, and forms, when ex- 
 tended, a square cone, and by the action of the gas this 
 flexible partition is distended first on one side of its vertical 
 plane and then on the other, so receiving and expelling the 
 gas — the number of times the leather partitions have been 
 distended, or the quantity passed, being recorded on the 
 dial. 
 
 Undoubtedly the simplest dry meter, and that most gene- 
 rally employed, is the instrument patented by Messrs. Croll 
 and Richards in 1844. This consists of a rectangular chamber 
 a a a a, Fig. 61, which is subdivided by a partition into two 
 
THE DRY METER. 
 
 231 
 
 distinct compartments. Each of these contains a flexible 
 chamber formed by a metal disc b, a ring attached to parti- 
 tion, and a soft leather belt A, which is secured air-tight 
 around the edge of disc and to the ring. Thus there are four 
 measuring compartments, 1, 2, 3, and 4, as seen in cut. The 
 action of these flexible chambers is similar to a bladder filled 
 with air, which air is afterwards forced out by being com- 
 pressed between two flat plates. 
 
 In the upper part, b, of the meter are two slide-valves, c c, 
 which convey the gas to and from the several chambers, and 
 
 o 
 
 Eig. 61. 
 
 are set in motion by a crank in communication with the 
 arms e e. These arms are firmly fixed to the rods c o, which 
 receive their motion from the discs b b, to which they are 
 communicated, so that the motion of the discs changes the 
 position of the valves. If we now suppose the gas to be 
 entering chamber No. 4, it would cause the disc b to travel 
 through a certain space, expelling at same time gas from 
 
232 
 
 LAYING MAINS AND SERVICES. 
 
 chamber No. 2, and during this period, for the supply to be 
 continuous, the gas would be admitted into chamber No. 1, 
 expelling that from No. 3, so filling and expelling the gas 
 from all the chambers in succession. The flexible chamber 
 being distended to its limits by the action of the valves, 
 the passages are reversed, and by this continued action the 
 flexible chambers distend and collapse alternately, in the first 
 place receiving the gas, which is afterwards expelled to the 
 burners of the consumers. 
 
 As already illustrated with the wet meter, the capacity of 
 the measuring vessels being known, the number of times 
 they have been filled and emptied, or the quantity consumed, 
 is communicated to the index g by means of wheel-work. 
 
 The action of the metallic discs in this meter has been 
 compared to that of the piston in a steam-engine; and 
 there is certainly a considerable analogy if the comparison 
 be made with the horizontal cylinders of a locomotive engine, 
 in which the motion of the piston is precisely the same as 
 that of the discs in this kind of meter. The system of slide- 
 valves for admitting the gas to the inside and outside of the 
 cylinders and to the exit pipe was pronounced by Mr. Clegg 
 to be extremely ingenious, and consists of a double series of 
 apertures, two of which lead respectively to the inside and 
 outside of one chamber, while the third in each series com- 
 municates with the exit pipe from each chamber. 
 
 CHAPTER XVI. 
 
 ON LAYING MAINS AND SERVICES FOR DISTRIBUTING GAS, AND 
 
 LEAKING IN MAINS. MAIN PirES FIRST USED. — VARIOUS 
 
 KINDS OF MAINS. — CHAMEROY PIPES. MODE OF MAKING 
 
 JOINTS. TABLE OF DELIVERY OF GAS PER HOUR. 
 
 CONDENSATION SYPHONS. — PRICES OF MAINS. — MEANS OF 
 
 DETECTING STOPPAGE IN MAINS. SERVICES. LEAKAGE 
 
 IN MAINS. 
 
 The pipes which convey gas or water through the different 
 streets are called main pipes or mains; and the small pipes 
 
LAYING MAINS AND SERVICES. 
 
 233 
 
 which convey the fluid therefrom to the houses are called 
 services. 
 
 Probably the first mains systematically laid throughout a 
 town or city, were those of the New River Company, up- 
 wards of two hundred years ago, for the purpose of dis- 
 tributing water throughout London. 
 
 These were simply trunks of elm trees left on the exterior 
 in their rude state, the interior being bored out to the re- 
 quired size, which varied from 2 inches to 10 inches diameter. 
 One end of this pipe was tapered like a spigot, from which, 
 no doubt, that part of cast-iron pipes takes its name ; the 
 other end had a conical seat to receive the spigot, and they 
 were joined together with whitelead, or cement, and “ driven 
 home ” with a mallet. 
 
 This rude state of laying mains existed until the com- 
 mencement of the present century, when the combined re- 
 quirements of gas and water led to the production of cast- 
 iron pipes ; but such was their excessive cost, when gas 
 companies commenced their operations, that £18 and £20 
 per ton was the ordinary price. By successive improvements, 
 introduced into this branch of industry, the price has gra- 
 dually diminished, and at the present day mains are less than 
 one-third of that cost. 
 
 At one period, when cast-iron mains were very expensive, 
 several attempts were made to substitute them by pipes of 
 other material. In a city, in the western part of England, 
 an extensive trial was made to transmit gas through brick 
 conduits. Earthenware pipes, similar to the drain pipes of 
 the present day, were also used ; and bottle-glass mains 
 were proposed, but never carried into operation. Pipes of 
 earthenware were used on an extensive scale in some of the 
 towns of France : their joints were made with Roman cement, 
 and the services attached by punching a hole therein and 
 inserting the end of pipe, which was secured with cement. 
 It is almost needless to say that this system resulted in com- 
 plete failure, and several gas companies were all but ruined 
 by resorting to it. 
 
 Subsequently a description of main was introduced into 
 France and the Continent, called after the inventor, the 
 
234 
 
 LAYING MAINS AND SERVICES. 
 
 “ Chameroy ” pipe. These are constructed of tinned or 
 leaded sheet-iron : the pipes, of 2 or 3 inches diameter, 
 being of the thickness of ordinary tin plate, but augmenting 
 in thickness according to the increased diameter, so that a 
 24-inch pipe is made of about No. 16 gauge plate. 
 
 In making these, the sheet-iron is turned round to form 
 the pipe, when it is riveted and soldered ; and on the re- 
 spective ends is cast corresponding male and female screws, 
 made of a composition of tin, lead, and antimony, which are 
 firmly soldered to the tube. The pipe then has a coating of 
 tar internally, and a layer of asphalte intermixed with sand, 
 of from ^ inch to ^ inch thick, according to size of pipe, on 
 the exterior ; when laid, they are screwed together with 
 a hempen washer dipped in tallow, forming a very sound 
 joint. Although apparently so very fragile, these pipes are 
 of extraordinary durability, many of them having been in- 
 terred upwards of twenty years without showing the slightest 
 symptoms of decay ; and, undoubtedly, the nature of the 
 material of which they are composed prevents to a great 
 extent the action known by chemists as “ endosmose ” and 
 “ exosmose,” which action is considered to exist to a serious 
 extent with cast-iron pipes, and is very detrimental to the 
 quality of gas transmitted through them. 
 
 By a law of nature all gases have a tendency to divide, 
 separate, or diffuse themselves, so that the poisonous air of 
 confined places, the vitiated atmosphere of large towns and 
 cities, or gases that may be engendered prejudicial to animal 
 life, are diffused, and fresh air takes their place. This law 
 is so powerful that gas, when confined in pipes, or gas- 
 holders, traverses the metal, and atmospheric air enters to 
 replace it; this is what occurs with gas in mains, and the 
 action is called endosmose and exosmose , derived from the 
 Greek, signifying impulsion, or pressure from within and 
 without. Of course, the more porous the substance confin- 
 ing the gas, the more powerful is this action ; hence the 
 necessity of having the metal forming the pipes as compact 
 as possible. 
 
 Cast-iron pipes are universally employed in England, and 
 their manufacture is at present brought to a great state of 
 
LAYING MAINS AND SERVICES. 
 
 235 
 
 perfection. As ordinarily made, when under 3 inches dia- 
 meter, they are 6 feet long and barely § inch thick ; when 
 under 12 inches and above 3 inches diameter, they are 9 feet 
 long, varying from § to \ inch thick ; when exceeding 12 
 inches diameter, they are often made 12 feet and 15 feet 
 long, but rarely exceeding f inch in thickness. 
 
 These pipes have on one end a socket, sometimes called a 
 “ faucet,’' sufficiently large in diameter to allow the end of 
 another pipe to enter very freely. These sockets vary in 
 length from 2 \ inches to 6 inches, according to the diameter of 
 main, the first being for 2-inch pipes; the latter for those 
 36 inches in diameter. The other end of the pipe is called 
 the spigot, and has a small bead cast on it, which prevents 
 the yarn passing into the interior when the joint is being 
 made. The quality of iron for pipes is of the most vital im- 
 portance : very soft black Iron contains a large proportion 
 of carbon, and this, by long use in the conveyance of gas, is 
 believed to change in its molecular nature, and becomes 
 sometimes so soft, that it can be cut with a knife, with the 
 greatest facility, like the crust of bread. 
 
 Previously to being laid, the pipes should be tested 
 separately by means of hydraulic pressure of at least two or 
 three atmospheres ; at the same time, a few blows struck 
 along that under examination with a hammer, will detect 
 any fault that may exist. Should there be any cracks or 
 flaws this will be perceived by the water oozing therefrom, 
 and that should be at once rejected. A sound pipe will 
 easily be distinguished from a cracked one by the ringing 
 noise it gives out when struck smartly with a hammer. 
 
 The joints of gas and water mains have been made in 
 several ways : the oldest, and undoubtedly the best, is done 
 in the following manner : — The spigot of the pipe about to 
 be laid is placed into the socket of that already laid, when 
 tarred gaskets of spun yarn are, by means of “ caulking,” 
 driven right into the socket for about half its length, and the 
 remaining portion is filled with molten lead ; which, when 
 cold, is caulked, or ‘‘set up” with a thick caulking-iron, 
 called a “set;” by this means the ring of lead is wedged 
 sufficiently tight to prevent the possibility of escape of gas. 
 
236 
 
 LAYING MAINS AND SERVICES. 
 
 Sometimes, when more than ordinary care is adopted, tho 
 joint is afterwards smeared or painted over with a composi- 
 tion of hot pitch and tallow, which serves to stop any very 
 minute leakages. In making these joints, care must be taken 
 not to have a superabundance of lead on the outer part of 
 the joint, or as termed “ too full a joint,” for in this case it 
 often happens that in “ setting up ” — particularly if the work- 
 men be inexperienced — the socket splits ; and if he conceals 
 the results of his awkwardness, probably a leakage of con- 
 sideration may exist during many years. The same casualty 
 is likely to happen if the joint is not “full enough,” when 
 the socket is often split by the tool being wedged in. The 
 operation requires great care. 
 
 The lead is poured into the joints by means of a belt of 
 plastic clay, attached around the edge of the socket, just 
 leaving sufficient space for the quantity of lead required, a 
 “gate” being left at the top, into which the metal is poured. 
 Another plan for pipes of large dimensions is, to have a flat 
 ring of about 1^ inch wide and J inch thick, the internal 
 part of which fits closely to the pipe. This ring is jointed 
 like a pair of callipers, which it resembles, and the two ends 
 are turned at right angles, with bolt-holes to bolt it together. 
 This replaces the belt of clay, and the interstices around it 
 and the pipe are rubbed over with clay when it is ready for 
 pouring the lead. This system, for large mains, is much to 
 be recommended, for making a good joint, and for the facility 
 with which it can be done. 
 
 Mr. Clegg recommends a mode of making joints without 
 lead, by a plan similar to that just described, but substi- 
 tuting tallow instead of metal. This has not been carried 
 into operation : experiments of this nature are dangerous and 
 costly ; moreover neither economy nor any other advantage 
 can be claimed for the system proposed. 
 
 Mr. Wicksted, engineer of the East London Water-works, 
 proposed a method of making joints of gas and water mains 
 by employing india-rubber rings, which were forced into the 
 sockets ; but although strongly advocated by that gentleman, 
 the system has not become general. 
 
 A superior plan of jointing pipes has been adopted for some 
 
LAYING MAINS AND SERVICES. 
 
 237 
 
 years in Liverpool and Manchester, which is found highly 
 successful when laid in straight lines or in curves of large 
 radius. In this method the socket of the pipe is turned with 
 a slightly conical opening, and the small end turned with a 
 similar conical figure to fit the socket. The two ends of the 
 pipes are covered with a mixture of red and white lead, and 
 being put together, are driven home by blows of a mallet. 
 This system has been applied in many instances with success. 
 
 In very large pipes of 4 or 5 feet diameter, the New River 
 Company has recently employed another means of making 
 joints. In this case a bead is cast on both ends of the pipe, 
 there being no socket. There is a collar or belt of cast iron, 
 about 7 inches wide, to fit on the outside of pipe, made in 
 three or more segments, which are jointed together by bolts 
 and nuts. The interior of this belt assumes the shape of, and 
 fits tolerably close on to, the beads of the two pipes to be 
 jointed. Previously to the iron belt being placed, there is a 
 band of felt, of about the same width as the belt, dipped in 
 tallow, placed around the pipes and over the beads, when the 
 cast-iron segments are placed and screwed up, making a good, 
 sound, cheap, and somewhat flexible joint. 
 
 In laying mains, the first consideration is the maximum 
 quantity of gas likely to be required for delivery per hour ; 
 this decided, then a point in the town where there will 
 be a general divergence of the pipes must be ascertained : 
 the distance between this point and the works being 
 known, the size requisite for the leading main may be ascer- 
 tained by referring to the very accurate table by Mr. Barlow 
 of the quantity of gas delivered per hour under certain pres- 
 sures, by various sized pipes, and of different lengths, pub- 
 lished in the “ Journal of Gas Lighting,” of which the follow- 
 ing is an abridgment. 
 
 The table is calculated on the supposition that the pipes 
 are on a level ; if there should be a descent to the part to 
 be supplied, they ought then to be somewhat larger ; on the 
 contrary, should there be a considerable ascent, their dimen- 
 sions may be diminished. The variation of the specific 
 gravity of gases for lighting will not materially influence the 
 sizes of the pipes. 
 
238 
 
 LAYING MAINS AND SERVICES. 
 
 Discharges of Gas in cubic feet per hour through Pipes of 
 various Diameters and Lengths, at different Pressures. 
 
 {The specific gravity of gas estimated at 400, air being 1,000.) 
 Diameter of Pipe 2 inches. 
 
 Length of main in yards . . 
 
 / with 0*2 inch pressure 
 ’■§ g „ 0*3 
 
 » 0-4 
 <5-3 l „ o-5 
 
 150 
 
 200 
 
 300 
 
 500 
 
 441 
 
 540 
 
 623 
 
 381 
 
 468 
 
 540 
 
 311 
 
 381 
 
 441 
 
 492 
 
 241 
 
 296 
 
 341 
 
 381 
 
 Diameter of Pipe 2J inches. 
 
 Length in yards 
 
 / with 0'3 inch pressure 
 
 ’■g © ) » 0 ' 4 „ 
 
 §a „ 0*5 
 
 \ » 0*6 
 
 150 
 
 200 
 
 300 
 
 500 
 
 943 
 
 1090 
 
 819 
 
 943 
 
 667 
 
 770 
 
 861 
 
 516 
 
 596 
 
 667 
 
 731 
 
 Diameter of Pipe 3 inches. 
 
 Length in yards . * . . . 
 
 f with 0*5 inch pressure 
 ’■go) „ 0-6 „ 
 
 § a ) » ®*8 „ 
 
 0?h~J v )> 1*0 ,, 
 
 500 
 
 750 
 
 1000 
 
 i 
 
 1250 
 
 1054 
 
 859 
 
 942 
 
 744 
 
 815 
 
 942 
 
 666 
 
 739 
 
 845 
 
 942 
 
 Diameter of Pipe 4 inches. 
 
 Length in yards 
 
 /with 0-6 inch pressure 
 » 
 
 ga i*o 
 
 \ „ i*5 
 
 750 
 
 1000 
 
 1250 j 
 
 1500 
 
 1932 
 
 1672 1 
 1932 1 
 
 1496 
 
 1728 
 
 1932 
 
 1366 
 
 1576 
 
 1761 
 
 2160 
 
LAYING MAINS AND SERVICES, 
 
 239 
 
 Diameter or Pipe 5 inches. 
 
 Length in yards j 
 
 750 
 
 1000 
 
 1250 
 
 1500 
 
 / with 0*6 inch pressure 
 ■fj © ) yy „ 
 
 Is „ i-o 
 
 (Sr S \ „ 15 „ 
 
 2888 
 
 2508 
 
 3174 
 
 2236 
 
 2828 
 
 3174 
 
 1934 
 
 2596 
 
 2877 
 
 3540 
 
 Diameter or Pipe 6 inches. 
 
 Length in yards 
 
 750 
 
 1000 
 
 1250 
 
 1500 
 
 .^'g / with 0*5 inch pressure 
 
 *■£ © \ yy 0*8 „ 
 
 f£ „ i-o 
 
 ■ <§-3 l „ 1-5 
 
 4860 
 
 4210 
 
 5320 
 
 3770 
 
 4740 
 
 5320 
 
 3430 
 
 4340 
 
 4860 
 
 5970 
 
 Diameter of Pipe 8 inches. 
 
 Length in yards 
 
 £/g / with 0-6 inch pressure 
 
 ■g © yy 9*8 ,, 
 
 is I. 1 -® 
 
 <§.§ l ,, 1-5 
 
 1000 
 
 1250 
 
 1500 
 
 1750 
 
 9450 
 
 10940 
 
 8480 
 
 9780 
 
 10940 
 
 7760 
 
 8940 
 
 9900 
 
 12200 
 
 7150 
 
 6260 
 
 9237 
 
 11300 
 
 Diameter of Pipe 10 inches. 
 
 Length in yards 
 
 £*"g / with 0*6 inch pressure 
 *~£ © ) » 9*8 „ 
 
 is) » 
 
 1000 
 
 1250 
 
 1500 
 
 1750 
 
 16500 
 
 19120 
 
 14800 
 
 17050 
 
 19120 
 
 13500 
 
 15600 
 
 17400 
 
 21300 
 
 12500 
 
 14400 
 
 16150 
 
 19600 
 
 Diameter of Pipe 12 inches. 
 
 Length in yards 
 
 1000 
 
 1250 
 
 1500 
 
 1750 
 
 / with 0*6 inch pressure 
 *"§ | ) yy 9*8 „ 
 
 is j „ i-o 
 
 Org V „ PS 
 
 26100 
 
 30200 
 
 23300 
 
 26900 
 
 30200 
 
 21400 
 
 24600 
 
 27500 
 
 33600 
 
 19800 
 
 22700 
 
 25450 
 
 31250 
 
240 
 
 LAYING MAINS AND SERVICES. 
 
 Diameter of Pipe 15 inches. 
 
 Length in yards 
 
 1250 
 
 1500 
 
 1750 
 
 2000 
 
 £?% / with 0- 8 inch pressure 
 
 47000 
 
 42800 
 
 39800 
 
 37200 
 
 *"£ QJ ) >> 10 ,, 
 
 52600 
 
 48000 
 
 44400 
 
 41600 
 
 M if 1*5 
 
 
 58700 
 
 54300 
 
 50800 
 
 <§•3 ’ » 2-0 
 
 
 
 62800 
 
 58700 
 
 Diameter of Pipe 18 inches. 
 
 Length in yards . 
 
 . . . . 
 
 1500 
 
 2000 
 
 2500 
 
 3000 
 
 #8 1 
 
 f with 0*8 inch 
 
 pressure 
 
 67600 
 
 58800 
 
 52300 
 
 33800 
 
 t £ 
 
 1 „ i*o 
 
 
 75700 
 
 65600 
 
 58800 
 
 53500 
 
 
 | „ 15 
 
 jf 
 
 
 80000 
 
 71800 
 
 65600 
 
 a-3 1 
 
 v „ 2-0 
 
 a 
 
 
 
 82800 
 
 75700 
 
 Diameter of Pipe 20 inches. 
 
 Length in yards 
 
 1500 
 
 2000 
 
 2500 
 
 3000 
 
 / with 0*8 inch pressure 
 "5 p j a 1‘0 ,, 
 
 §£ ) „ 1-5 
 
 \ a 2-0 
 
 88000 
 
 98800 
 
 76500 
 
 85300 
 
 102300 
 
 68400 
 
 76500 
 
 93500 
 
 108000 
 
 62400 
 
 69800 
 
 85300 
 
 98800 
 
 Diameter of Pipe 24 inches. 
 
 Length in yards 
 
 ^ / with 0*8 inch pressure 
 g ? a 
 
 §5 „ 15 
 
 <§3 \ n 2*0 
 
 1500 
 
 2000 
 
 2500 
 
 3000 
 
 137200 
 
 155000 
 
 119000 
 
 135600 
 
 163000 
 
 106000 
 119000 
 145500 
 168000 ! 
 
 97000 
 
 108600 
 
 135600 
 
 155000 
 
 Diameter of Pipe 28 inches. 
 
 Length in yards 
 
 ( with 0 -5 inch pressure 
 *■§ ® ) » 1,0 » 
 
 <5-3 \ » 2-0 
 
 1500 
 
 2000 
 
 2500 
 
 3000 
 
 161000 
 
 229000 
 
 280000 
 
 140000 
 
 198000 
 
 241000 
 
 280000 
 
 125000 
 
 177000 
 
 216000 
 
 250000 
 
 114500 
 
 161000 
 
 198000 
 
 229000 
 
LAYING MAINS AND SERVICES. 
 
 241 
 
 Diameter of Pipe 30 inc&ies. 
 
 Length in yards 
 
 1000 
 
 2000 
 
 3000 
 
 4000 
 
 Quantity- 
 
 delivered 
 
 f with 0.5 inch pressure 
 
 ► „ i*o 
 
 1 1*5 » 
 
 v ,, 2*0 
 
 234000 
 
 332000 
 
 166000 
 
 234000 
 
 287000 
 
 135000 
 
 192000 
 
 234000 
 
 270000 
 
 117000 
 
 166000 
 
 203000 
 
 234000 
 
 Diameter of Pipe 36 inches. 
 
 Length in yards 
 
 1000 
 
 2000 
 
 3000 
 
 4000 
 
 / with 1*0 inch pressure 
 
 o 1 ) » 1-6 » 
 
 §£ » 2 -°. 
 
 „ 2*5 „ 
 
 530000 
 
 372000 
 
 456000 
 
 303000 
 
 372000 
 
 428000 
 
 265000 
 
 322000 
 
 372000 
 
 416000 
 
 To apply this table, let us suppose the maximum con- 
 sumption per hour in a town to be 10,000 feet, the length of 
 main from works to general divergence 1,500 yards, and the 
 maximum pressure 1 inch, then on reference we find a close 
 approximation to the quantity, and that an 8-inch leading 
 main would be necessary. 
 
 The principal leading main having been decided on, in a 
 similar manner approximations must be made of the various 
 quantities likely to be required per hour in each distinct 
 locality, and providing the mains accordingly, taking into 
 due consideration the probabilities of improvement or increase 
 in the various districts. 
 
 It is of the utmost importance to have the main pipes suf- 
 ficiently large ; many companies have lost considerably by 
 the escapes of gas caused by the high pressure necessary 
 with small mains ; afterwards, when they were increased in 
 size, the loss by escapes was reduced materially, and the 
 company’s profits increased in like proportion. The first 
 leading mains that were laid to supply London with gas were 
 3 inches in diameter, now there are several works which have 
 them 36 inches diameter. 
 
 It is very important to have a good map, not only of the 
 site of the works, but of the whole district to be supplied 
 
242 
 
 LAYING MAINS AND SERVICES. 
 
 with gas ; on this map the course of all mains should be laid 
 down, and the position of all syphons or water receivers should 
 be marked. 
 
 In addition to a mere surface plan, a network of levels should 
 be taken over the whole district, and the grades or inclina- 
 tions of all the mains marked on. The relative elevations of 
 the whole district with reference to some fixed point near the 
 gasholder would be best shown by contour lines of equal 
 heights drawn throughout the district. When the town is 
 nearly all on the same level, contour lines may be laid down 
 at intervals of 2 or 3 feet vertical height, but where the 
 streets are very steep, intervals of 6 or 8 feet would be suf- 
 ficient. The best rule for laying on the contours is, that 
 they ought to be so frequent as to show by a mere inspection 
 of the map the level of every part of the surface with refer- 
 ence to the fixed datum line. 
 
 The admirable surveys of towns made under the directions 
 of the officers of the corps of Royal Engineers, and plotted 
 on a scale of 5 feet to 1 inch, are exceedingly well adapted 
 for the delineation of gas and water pipes. The further 
 information relative to the levels of the streets, the inclination 
 of the mains, &c., will be readily added by a competent per- 
 son, and will constitute the map a very valuable instrument 
 in the hands of the gas company. There are as abundant 
 examples of the mistakes made by gas and water companies 
 as by commissioners of sewers, for want of proper maps 
 delineating their under-ground works. Much economy and 
 efficacy may be expected where the circumstances of each 
 district as to levels and pressure can be at once ascertained, 
 while on the other hand great losses are frequently occasioned 
 by an ignorance of such particulars. It has been asserted 
 by a writer on this subject that in a street of half a mile in 
 length not less than twelve syphons have been discovered on 
 taking up the main, while one, or at most two, would have 
 been sufficient to drain the main. Blunders of this kind are 
 evidently occasioned by the want of maps to refer to, show- 
 ing the works already executed, and which would have ren- 
 dered unnecessary the repeated reconstruction of the same 
 works. 
 
LAYING MAINS AND SERVICES. 
 
 243 
 
 Mr. Clegg recommends, wherever practicable, that the 
 main pipes should be connected to each other by cross pipes, 
 which produce the effect of equalising the pressure of the 
 gas at every point. Where this is not practicable, and where 
 the irregularities of the district to be lighted are considerable, 
 he recommends the use of a governor to reduce the pressure 
 in the higher districts. It is generally considered that a 
 governor is necessary when a difference of level equal to 60 
 feet exists, so that there are many towns which would require 
 several governors in order to make the pressure more uni- 
 form in the mains. 
 
 Generally the mains are laid in or near the centre of the 
 road, but when the streets are very wide they are often laid 
 on each side near to the houses, the latter plan being adopted 
 to avoid the expense of long services. Gas in its passage 
 from the works carries with it a quantity of vapour of water ; 
 this depending on the degree of condensation to which it 
 has been submitted in the manufacture, or on the tempera- 
 ture of the water in the tanks of the gasholder, which in- 
 fluence the amount of vapour intermixed with the gas. The 
 vapour existing from either of these causes, in its passage 
 through the pipes underground is condensed, and if no pro- 
 vision were made the water would eventually obstruct the 
 pipes and stop the passage of the gas ; therefore water 
 receivers (or syphons , as generally, although improperly, 
 called) are placed at certain intervals to collect the liquor 
 caused by condensation. Of necessity the mains must always 
 incline into these syphons, to enable the water to drain into 
 them, which is afterwards pumped out when desirable. 
 
 These syphons are cylindrical vessels of cast iron, closed 
 at top and bottom, having a socket on one side and spigot on 
 the other, cast therewith, so that they may be connected 
 to the main, of which they form a continuation. In the 
 centre of the upper plate, or cover, is a f-inch pipe, which 
 descends to nearly the bottom of the syphon, and a similar 
 pipe, screwed on to this, and having a cap thereon, con- 
 tinues to nearly the level of the ground, where it is sur- 
 mounted by a box, or trap, generally of cast iron. On open- 
 ing this trap, the cap of the syphon pipe can be unscrewed 
 
 M 2 
 
244 
 
 LAYING MAINS AND SERVICES. 
 
 and a pump attached, so that any water in the vessels is 
 easily removed. These vessels vary in size according to 
 the main to which they are attached. Having the principal 
 levels of a town, the position of the various syphons is easily 
 decided, unless some unforeseen obstacle presents itself, such 
 as sew 7 er, water-pipes, &c., 'which may render a slight alter- 
 ation necessary. The syphons should be as few as possible 
 consistent with the perfect drainage of the mains, thus avoid- 
 ing unnecessary expense in placing them, unnecessary labour 
 in trying them, and the probability of some of them being 
 neglected. 
 
 Much is often said of the large quantity of gas condensed 
 in its transit; this is decidedly erroneous, for if the vast con- 
 densation existed, which many pretend, it would be made 
 apparent by the liquid deposited in the syphons. That this 
 liquid arises from the condensation of vapours carried off 
 with the gas is made manifest by the fact, that in summer, 
 when the production of gas is at the minimum, the condensa- 
 tion in the syphons is at the maximum, arising from the 
 heat of the holder and the gas therein, which causes a large 
 quantity of vapour to pass off into the mains. Another 
 proof that this does not arise from the condensation of the 
 gas is the nature of the liquid itself, which is neither more nor 
 less than ammoniacal liquor. Therefore, with every confi- 
 dence, we may say that the loss from condensation in mains, in 
 the ordinary way of manufacturing gas, is not equal to one- 
 thousandth part of the whole ; but when gases are so produced 
 that the hydrogen does not chemically combine with the 
 carbon, or when subjected to severe cold, then the deposit 
 of the latter by condensation is often very considerable. 
 
 Leakage in mains is a continuous and serious source of 
 loss to a company ; therefore, gas mains should never be 
 laid with undue haste ; the operation requires the utmost care, 
 for on this greatly depends the success of the enterprise. 
 
 An excellent plan to preserve pipes and to prevent leakage 
 to some extent is to immerse them when hot into a vessel 
 containing thin pitch, afterwards placing them erect to allow 7 
 the surplus to drain off, taking care previously to paint 
 over the part of the spigot that enters the socket, as w T ell as 
 
LAYING MAINS AND SERVICES. 
 
 245 
 
 the interior of the socket, with loam intermixed with water to 
 form a paste, allowing this to dry previously to immersion. 
 The loam breaks off when the pipe is cold, leaving that part 
 for making the joint entirely uncovered; if this were not 
 done the pitch might prevent the joint being sound. 
 
 The position of the works in relation to the locality to be 
 supplied, together with the size of the leading mains, must 
 determine the pressure at which the gas should be delivered ; 
 thus, a town and works being on the same level, if the mains 
 are ample, the gas having a pressure of 1 inch to 1| inch 
 at the outlet of works should be sufficient for the supply of 
 the whole district. 
 
 Some extraordinary instances have occurred where, either 
 by error or necessity, the works have been situated at the 
 highest part of the district ; when this happens the pressure 
 must be increased very considerably, in order to supply the 
 lower districts. 
 
 When the works are situated very low, sometimes, for 
 the sake of economy, the gas may issue *at an exhaust of 
 -j^ths or ! 5 0 ths of an inch, this being dependent on the 
 position of the nearest light to be supplied. When mains 
 are obstructed either by the deposit of naphthaline, or by 
 water accumulated in consequence of not having drainage, 
 a portion, or perhaps the whole, of the district is often without 
 a proper supply of gas, occasioning the manager much 
 annoyance and trouble. The way to discover the point of 
 the main so obstructed is of the greatest simplicity. 
 
 To detect where a stoppage exists in a main, recourse 
 must be had to the pressure-gauge ; with this the pressure 
 should be taken on the line of main when in full light- 
 ing , at various intervals of say 100 or 200 yards, commencing 
 from the works. This may be done on the public lamps or 
 on the premises of a consumer ; but it is imperative that no 
 light be burned on the same service during the trial, as this 
 would cause a variation from the true pressure on the main, 
 caused by the friction of the meter, or the gas passing through 
 the pipes. 
 
 Following the line of main, and noting the pressure at 
 each point where tried, if the decrease of pressure be gra- 
 
246 
 
 LAYING MAINS AND SERVICES. 
 
 dual, this will be due to the friction of the gas in passing; 
 and should it gradually decrease until insufficient for sup- 
 plying the lights, then the main is too small for the quantity 
 of gas delivered. But should the decrease of pressure be- 
 tween one point and another, say in a distance of 100 yards, 
 be sudden and excessive, then it may be concluded that an 
 obstruction exists between these two places. This ascer- 
 tained, perhaps it may be necessary to fix air-pipes, these 
 being simply -|-inch or |-inch short pieces, screwed into the 
 main, closed by a plug or cap, which are placed at various 
 parts where tlie stoppage is suspected, with a block over 
 them, and during full lighting the pressure is again tested on 
 these air-pipes, when the stoppage may often be detected 
 within a few yards. The remedy then is to cut the main, 
 and remove the naphthaline, if that should be the cause ; or 
 should the stoppage arise from an accumulation of water, the 
 main must either be relaid or a syphon placed. 
 
 The porosity of cast iron has long been a well-ascertained 
 fact, and numerous experiments have been quoted to show 
 that under high pressure even water may be forced through 
 its pores and made to appear as a damp film on the outside 
 of pipes. It is also certain that ordinary cast-iron pipes are 
 permeable by gas, as the soil in contact with gas-pipes is 
 almost invariably found to be saturated with gas, nor is the 
 saturation confined to the joints, but continuous throughout 
 the length of the pipes. These facts render it evident that 
 great attention should be paid to the quality of the cast iron 
 of which the pipes are composed, and that the pipes them- 
 selves should be tested by a pressure of water, as in the case 
 of water-pipes. Much greater attention is also now paid to 
 the joints, which are made in a very superior manner to those 
 formerly in use, as the success of an establishment is prin- 
 cipally dependent on the soundness of the mains. 
 
 Subjoined is a table of the average weight of pipes, and 
 their price per yard at various rates per ton ; also an average 
 price when laid in ballast at an ordinary depth. The price 
 for paving must vary with the locality : often in London the 
 ground opened has to be repaved in part or entirely a 
 second time, which of course increases the expense. 
 
Table of Weight and Cost Price of Cast Iron Main Pipes. 
 
 LAYING MAINS AND SERVICES. 
 
 247 
 
 
 
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 Diameter of pipe in inches . 
 
248 
 
 SERVICES. 
 
 SERVICES. 
 
 Services are the pipes which convey the gas from the 
 company’s main to the consumers’ premises. Those in Eng- 
 land are universally of iron tube, called gun-barrel, which in 
 some description of soil is of great durability, therefore 
 cannot be superseded by anything better; but there are other 
 localities, such as towns which are on the sea-shore, having a 
 sandy soil, where it is speedily destroyed. 
 
 Whenever gun-barrel is used, it should always previously 
 be heated, and ‘have a good coat of tar to prevent it oxydis- 
 ing ; the workman when using it should only screw it by the 
 socket, otherwise he will scrape off the pitch, exposing that 
 part of the pipe to the destructive influence of the damp, &c. 
 
 On the Continent, generally, lead pipe is used for services; 
 its durability is very remarkable, but it requires more care 
 in laying, in order to keep it even ; for that purpose it is 
 usual to place a lath of about ^ an inch thick and 3 inches 
 wide underneath it, which serves as a bed for the pipe, and 
 prevents the uneven places, which would otherwise form 
 and retain the water. 
 
 The holes in gas mains should always be drilled : the 
 clumsy and shapeless manner in which some men gouge them 
 out is often the cause of great loss to the company. 
 
 Services should always be laid with a declivity towards 
 the main, so that water cannot lodge in them; if this hap- 
 pened, it would cause at first oscillations of the lights, and 
 afterwards a complete stoppage in the supply. Sometimes 
 services are stopped by naphthaline, water, rust of iron, 
 &c., wdiich is effectually removed by the service-cleaner of 
 Messrs. Hulett and Co. This instrument is a kind of force- 
 pump, and when applied to the obstructed pipe it is imme- 
 diately cleared. 
 
 The oscillation or jumping of lights is due to a portion of 
 water deposited in the pipe through which the gas passes ; 
 the pressure of the gas at one moment forcing a passage for 
 itself through the water, and at another moment being ob- 
 structed by the water. When services cannot be laid with 
 an incline into the main, a syphon should always be placed 
 
ON THE LEAKAGE OF MAINS. 
 
 249 
 
 to collect the condensation ; this is formed with a tee-piece, 
 with a short piece of pipe, and bends in a very simple 
 manner ; syphons are also made expressly for the object. 
 
 On the Continent, generally, there is a main -tap on the 
 exterior of premises attached to the service supplying, for the 
 purpose of shutting off in the event of fire. These taps 
 were also formerly used for turning on and off the supply 
 daily to contract consumers : at sunset a workman of the 
 company turned on to each house, and again went his rounds 
 at the various hours, according to the respective contracts, 
 to shut off the gas. By these means such serious loss as was 
 incurred at one time by gas companies in England, where 
 the supply was kept on continuously, was prevented. 
 
 Galvanised gun -barrel resists very effectually the action of 
 rust. The increase of price is an obstacle to its use ; but 
 in certain soils it is invaluable on account of its durability, 
 and preventing loss of gas by decay of the services. 
 
 ON THE LEAKAGE OF MAINS. 
 
 This is a subject of great importance, and one which 
 varies so much under different circumstances as to produce 
 great influence on the returns of gas companies. Where 
 every degree of foresight and economy has been exercised 
 in the actual manufacture of the gas, it may afterwards be 
 so much diminished by leakage between the gasholder and 
 the meters of the consumers as to reduce the profits of the 
 company to an alarming extent; indeed, in some instances 
 has been ruinous. The amount of leakage is variously esti- 
 mated at from 10 to 25 per cent. Many gas managers insist, 
 with every reason, that when the mains and services are 
 properly laid, and other necessary precautions taken, the 
 loss by leakage should not exceed 10 per cent. Mr. Croll, 
 in his parliamentary evidence, estimated that one-sixth of 
 the whole gas sent out would be absorbed by leakage and 
 stealage ; but in this must also be included the loss of gas 
 occasioned by laying new mains, services, and alterations, 
 which loss at times is very great, and demands the serious 
 attention of engineers to prevent it. 
 
 Mains are now laid in a very superior manner; and the 
 M 3 
 
250 
 
 ON THE LEAKAGE OF MAINS. 
 
 oldest gas-works are those in which the most extensive leak- 
 age prevails. There is also reason to suppose that the pipes 
 are now cast in a superior manner, the metal being closer and 
 more solid in texture, so as not to admit of so much leakage 
 as that which prevails in porous and imperfect castings. 
 
 It has been remarked that Professor Graham once found 
 25 per cent, of atmospheric air intermixed with the gas 
 in its passage, which has been assumed to arise from the 
 action of endosmose and exosmose before described ; but it is 
 difficult to imagine this to have been the cause. More pro- 
 bably the main was opened in a very low part of the district, 
 where there was no pressure, and the air entering there 
 was intermixed with the gas under examination. Gas often 
 enters water-mains under similar conditions, there being a 
 leakage in the water-main at the highest part of the district, 
 also in the gas-main adjoining ; the gas is drawn into the 
 water-pipe by a partial vacuum being formed therein, occa- 
 sioned by the water escaping through a valve, or otherwise, 
 at a part in the lower district. 
 
 The effect of excessive pressure on the gas when de- 
 livered into the mains tends considerably to increase the 
 leakage ; and when the proper supply cannot be maintained 
 without this, the more promptly the mains are replaced by 
 those of larger and proper magnitude the greater will be the 
 profits to the company. Sometimes the expense deters many 
 from carrying the improvement into operation ; but sooner 
 or later it must be done, and often by deferring it is post- 
 poned until too late. For after consumers have complained 
 repeatedly of insufficiency of supply, without redress, an 
 opposition company makes its appearance ; and in some 
 instances, after strong contention, the opposing has bought 
 up the original company. A gradual stoppage in a leading 
 main will have a similar effect as if the main were insufficient 
 in size. 
 
 The losses by leakage will be diminished materially by 
 following the instructions in the article on “ Laying Mains” 
 — by proving the pipes previously to being laid — by stopping 
 their pores with bitumen — by coating the joints of the pipes 
 afterwards with a flexible, impermeable composition — by 
 
PRESSURE GAUGE. 
 
 251 
 
 drilling, instead of gouging, the holes for the services — 
 lastly, by making the service and main layers fully under- 
 stand the valuable article they have at their control, and to 
 adopt every means to prevent its loss. 
 
 Sometimes the burners of the public lights deliver con- 
 siderably more than their stipulated quantity, and give, 
 through the excess of pressure, diminished light ; or, as it 
 occurred in a London company’s district a few years ago, 
 the meters had been so terribly neglected and decayed, that 
 many of them did not register, whilst others only indicated 
 a portion of the gas which passed. These and similar 
 losses are generally put to the account of leakage. Cases 
 like these are by no means uncommon 
 
 CHAPTER XVII. 
 
 ON APPARATUS FOR INDICATING AND RECORDING PRESSURE I 
 PRESSURE GAUGE. PRESSURE INDICATOR, AND REGISTERING 
 PRESSURE GAUGE. 
 
 PRESSURE GAUGE. 
 
 As already stated, when coal is distilled the heat decomposes 
 it, and the gas is expelled in a manner analogous to the 
 production of steam from water; the gas, when confined 
 under ordinary pressure in a holder, assuming a bulk about 
 250 times greater than that of the coal from which it ema- 
 nated, and if not retained by this means, dividing or diffus- 
 ing itself to an indefinite extent. When gas is so confined 
 the gasholder may be so counterbalanced as to prevent it 
 issuing ; therefore, there being no weight, there would be no 
 pressure, and by further counterbalance air would enter and 
 intermix with the gas. 
 
 The pressure of gas depends on a number of circumstances, 
 such as the weight and area of holders, the size of pipes 
 through which it passes, the means of purification, the seal or 
 dip of hydraulic mains, and other obstacles which may be 
 presented to its free passage ; and it is essential to the strict 
 
252 
 
 TOESSUKE GAUGE. 
 
 economy of a gas establishment that the pressure existing 
 in all the parts of the manufactory, as well as in the mains 
 for distribution, should be known. For this purpose a simple 
 instrument called the “ pressure gauge” is employed, which 
 consists in its simplest form of a glass tube about -§ inch 
 internal diameter, and 6 or 8 inches long, bent in the form of 
 the letter U, with the two legs approached as near as possible 
 to each other. Between the two tubes is a scale, the centre 
 being marked zero, and the space above and below is sub- 
 divided into inches and tenths of inches. The gauge is filled 
 with water to the line marked zero on the scale, and when 
 not influenced by the pressure of the gas, the water, of course, 
 stands at the same level in both tubes. 
 
 When required for use, one end of the gauge is attached 
 to the pipe through w T hich the gas is passing, when the pres- 
 sure of the gas causes the water in one of the tubes to be 
 depressed, and to be elevated in the other, the difference 
 between the two water levels, as read on the scale, being the 
 pressure of the gas. For example, if the water be depressed 
 half an inch below the point marked zero, and elevated the 
 same distance above, the pressure will be y§ths ; the scale 
 may be dispensed with, and the difference of levels taken with 
 an ordinary measure, and the pressure so ascertained. 
 
 These gauges are often made with two straight tubes con- 
 nected at top and bottom by a small chamber. The advan- 
 tages of this system are, that the tubes are easily taken apart, 
 and can be readily cleaned ; they can also be made much 
 stronger. The bent tubes are very liable to break. 
 
 In many establishments the maximum pressure in the town 
 does not exceed 1 inch to 1^ inch, a minimum pressure of 
 -fjyths being obtained in the lowest parts of the district, 
 which is sufficient and ample. In others, however, perhaps 
 from the position of their work? the size of mains, or the 
 elevation of the locality supplied, much greater pressure is 
 required. For ordinary purposes, as when ascertaining the 
 pressure in the mains of the town, a gauge 5 or 6 inches long 
 is sufficient. i 
 
 The pressure in the streets may be ascertained by attaching 
 the gauge by means of a flexible tube to the lamp burners, 
 
PRESSURE GAUGE. 
 
 253 
 
 or, if more convenient, on the premises of a consumer, but 
 taking care that there is no supply from the same service. 
 This operation is only done occasionally in the event of 
 stoppages, or the mains being too small, in order to ascertain 
 the defect. 
 
 In gas-works, where the pressure is often equal to from 
 18 to 30 inches of water, caused by the weight of holders, 
 the dip of washers, the smallness of mains, or perhaps from 
 obstructions in the pipes, then gauges are made to suit the 
 circumstances, and as the greatly increased length would 
 prevent them being placed in many situations, mercury 
 gauges are often employed ; these are constructed precisely 
 similar to the water gauge, but the tubes are much narrower, 
 being only about £ inch in diameter, and contain mercury 
 instead of water. 
 
 Mercury, at ordinary temperatures, is a fluid about thirteen 
 and a half times heavier than water ; it consequently requires 
 a proportionate amount of force or pressure to raise a 
 column a given height. Or a given variation in the two 
 levels of a mercury gauge indicates thirteen and a half 
 times that pressure in water ; so that instead of requiring a 
 water gauge 40 inches long, a mercurial gauge of 3 inches 
 will be sufficient. 
 
 There are other means of indicating pressure, by closed 
 vessels being divided into two distinct compartments, and 
 water being able to pass freely from the one to the other. 
 In one of these compartments is placed a float, with a rod 
 attached to it, passing through the cover of vessel, which is 
 provided with a scale. The gas enters one compartment, 
 and depresses the water therein, consequently elevating it 
 in, the others, by which means the float is raised and the 
 pressure shown on the scale by a pointer on the end of rod 
 attached to float. This principle is applied in various ways, 
 sometimes with a dial in the centre, or with a pointer and 
 semicircular scale, and instruments of this class are often 
 made very ornamental. 
 
 The gauges above described only indicate the pressure 
 acting on them at a particular moment, and leave no record; 
 but there are other instruments employed which not only 
 
254 
 
 PRESSURE REGISTER. 
 
 indicate bat record rigidly throughout the day and night the 
 pressure which has acted on them. Of these there are two 
 kinds — the one called the Pressure Register or Indicator 
 the other the Registering Pressure Gauge. 
 
 THE PRESSURE REGISTER OR INDICATOR. 
 
 This instrument in France is called the spy, “ le mouchard ,” 
 signifying its duty to keep watch over and record the 
 manner the workmen attend to their duty in the delivery of 
 gas to the districts. Its action is automatic and continuous, 
 requiring the application of a clock to indicate the various 
 periods of time, whilst means are adopted to record the 
 pressure. 
 
 This instrument consists of a tank of cast-iron or tinned 
 plate, of about 3 feet deep and 16 inches diameter, in the 
 centre of which rises to about midway a vertical pipe in 
 connection with the main. The top of the tank has a 
 domed cover, on which is a receptacle for a vertical revolving 
 cylinder of about 16 inches long and 5 inches diameter, the 
 whole being surmounted by a clock, attached to the cylinder 
 in such a manner as to cause it to revolve once in the 24 
 hours. In the tank there is a gasholder of about 14 inches 
 diameter and 16 inches high, having a float throughout its 
 length to give it the required degree of buoyancy when 
 immersed, but which gives increased weight on rising. The 
 holder has proper rollers and guides to enable it to rise and 
 descend with every freedom. Attached to the top of the holder 
 there is a rod which passes through the centre of cover of 
 tank, and on the top of this rod is a spring pencil for the 
 purpose of recording. 
 
 Around the vertical cylinder is coiled a sheet of paper, 
 which is marked into twenty -four vertical divisions, to indicate 
 the hours of day and night, corresponding with the clock 
 above. There are also a series of horizontal lines correspond- 
 ing with the pressure, commonly being forty or fifty tenths, 
 which are numbered, commencing from the bottom marked 
 zero. The tank being supplied with water to the desired 
 height, if there be no pressure the pencil will remain at 
 zero ; but if the gas be admitted, say at a pressure equal to 
 2 inches, the holder rises, and with it the pencil, which 
 
REGISTERING PRESSURE GAUGE. 
 
 255 
 
 records on the horizontal lines of the coil of paper, and the 
 vertical lines indicate the period that such pressure existed. 
 By these means the slightest irregularity, if only existing for 
 a minute, is recorded on the paper. 
 
 THE REGISTERING PRESSURE GAUGE. 
 
 The registering pressure gauge, represented by Fig. 62, 
 is a much smaller and cheaper instrument than the former, 
 
 and was invented by the late Mr. A. Wright. Its size 
 renders it very portable, its moderate price permits its being 
 adopted by works of all descriptions, and it is largely used by 
 gas companies to record the pressure existing in different 
 parts of their districts. 
 
 This instrument consists of two concentric cylinders, the 
 outer one, or case, a a } being about 16 inches diameter, and 
 
256 
 
 REGISTERING PRESSURE GAUGE. 
 
 10 inches deep, closed at its base, also at the top over the 
 annular space between it and the inner cylinder, c. These 
 cylinders communicate with each other only through a small 
 space left between the lower edge of the inner, and the 
 bottom of the outer cylinder. The case is surmounted by a 
 clock enclosed in a glass shade. The clock, instead of having 
 an ordinary face, is provided with a metal disc which carries 
 a circular sheet of paper divided by twenty -four radiating 
 lines corresponding with the hours of day and night ; also 
 having a series of concentric rings according with the various 
 pressures. A float carrying a rod, d, and pencil similar to 
 that of the Pressure Register, is placed in the inner cylinder, 
 which is open at top. When required for use, water is 
 poured into the vessel c until about half full. Gas being 
 then admitted to the upper part of outer cylinder by pipe b f 
 depresses the water in the annular space, and elevates that 
 in the inner cylinder, precisely as in the gauges described, 
 thereby lifting the float, causing the pencil to make a mark, 
 high or low, in agreement with the pressure acting. 
 
 Fresh sheets or discs are required daily, which should all 
 be dated, and as they may become very important records, 
 should be carefully preserved. These instruments are very 
 essential — they serve to correct irregularities, to prevent 
 blame being imputed in improper quarters, and point out 
 when any complaint arising from irregularity of pressure has 
 been made, not only at what station, but at what precise 
 hour, and under whose management this has occurred. 
 These records serve in the most delicate manner to check 
 the pressure, and enable the superintendent to adjust it to 
 the requirements of the district during the successive stages 
 of the twenty-four hours, in which a remarkable variation 
 takes place in the quantity of pressure required. For 
 instance, there are some works which throughout the day 
 scarcely require a greater pressure than three-tenths of an 
 inch, though towards the time of lighting up the streets, 
 shops, and private houses, the pressure requires to be in- 
 creased to 3 or even 4 inches, and this continues till the hour 
 when many of the shop lights and private house lights are ex- 
 tinguished. Another diminution occurs about twelve o’clock, 
 when most of the public-house lights are put out, and few 
 
THE GOVERNOR. 
 
 257 
 
 lights continue burning except the street lamps. The night 
 pressure is further diminished to its minimum about the hour 
 when the street lamps are extinguished, and continues at its 
 minimum low state throughout the day. 
 
 There is a modification of this instrument for the use of 
 gas-works, which records the action of the exhauster, being 
 very useful to prevent undue exhaustion, to which cause 
 must undoubtedly be attributed the great variation existing 
 from day to day in the quality of gas supplied by companies, 
 as recorded by the chemical inspectors. 
 
 CHAPTER XVIII. 
 
 THE GOVERNOR AND REGULATOR. 
 
 The governor is one of those ingenious self-acting machines 
 which are equally admirable for their efficiency and simplicity. 
 It is placed between the gasholder and the main pipe in 
 order to regulate the pressure of gas admitted into the latter, 
 and acts quite independently of any irregularity due to the 
 unequal action of the gasholders or to other causes. The 
 governor is also important in another point of view, viz., 
 where a town has great variation of elevations, and where, 
 without some contrivance to prevent it, the pressure of gas 
 in the higher levels would be very excessive and alike pre- 
 judicial to the company and consumer. 
 
 This instrument is a single-lift gasholder and tank, having 
 a peculiar valve in connection therewith, so that the pres- 
 sure is always regulated according to the weight placed on 
 its holder. The tank is made of cast-iron, its dimensions 
 being dependent on the size of the mains for which it is 
 destined, and the manner in which the apparatus is made. 
 
 Fig. 63 is a view of a governor, the tank and a part 
 of the holder being in section, in order to show the inte- 
 rior ; a a is a cylindrical tank, having the columns b b to 
 support the bridge e e, in the centre of which is a guide 
 lor the flat rod d. The holder g is made of tinned iron, has . 
 a conical plug suspended in it, and works very freely in the 
 tank, being guided by rollers at its lower edge and the flat 
 
258 
 
 THE GOVERNOR. 
 
 rod d above. The inlet pipe is exactly in the centie, and 
 has a conical-seated flange at top ; the outlet pipe being 
 concentric to it, rises considerably above the level of water. 
 
 The holder is provided with an annular float, o o, of such 
 buoyancy, that when the tank is charged with the proper 
 
 Fig. 63. 
 
 quantity of water, it rises, carrying with it the suspended 
 conical plug h, the base of which is turned and fitted to the 
 flange on top of inlet, so as to be hermetically tight. The 
 action of the instrument is very simple, for being supplied 
 
THE GOVERNOR. 
 
 259 
 
 with water to the proper height, and supposing the weights 
 n n to be taken off, the holder ascends, lifting with it the 
 conical plug, which, when at the top, stops the supply of 
 gas. Under these circumstances the governor is destined to 
 give no pressure. Now, if a pressure of xS-ths be requisite 
 on placing weights on the holder equivalent to that pressure 
 — no matter whatever variations may take place in the pres- 
 sure in the works, or the quantity of gas being consumed 
 in the town — the same pressure is strictly maintained by the 
 governor ; if the quantity supplied be great, the holder 
 descends with the plug, and so increases the size of orifice ; 
 and should the quantity passing be small, the holder rises, 
 and the plug closes the aperture, so that this simple machine 
 delivers at all times any quantity of gas at the pressure 
 desired, according to the weights on the holder. 
 
 Another modification, called Wright’s governor, is to sub- 
 stitute the float by a pillar lever-beam and counterbalance 
 weights, the variation of pressure being obtained by adding 
 or subtracting weights ; in other respects this instrument is 
 precisely like the other. 
 
 No gas works should be without a governor ; in some 
 instances, where the whole pressure of works is left on the 
 mains continually, it would repay its purchase-money in a 
 month by the saving effected in gas from diminished leakages, 
 tii many works the foreman, or stoker, has continually to 
 regulate the pressure during the hours of lighting by means 
 of a valve, giving much trouble, and the work is done very 
 imperfectly. 
 
 When there are great variations of levels in towns, 
 governors are sometimes placed on the mains ; but for this 
 purpose they are fixed on the principal main only ; and the 
 branch mains from one governor should be disconnected from 
 those of another. Thus, if the highest level of a town be 
 200 feet — by placing a governor at an elevation of 50 feet, and 
 another, say 100 feet, and the third at 150 feet — the pipes sup- 
 plied from the governor at each level should be quite detached 
 from the others, otherwise the instrument would be useless. 
 
 Another mode of governing the pressure of gas, is by 
 means of a loose diaphragm of leather affixed to the top of 
 
260 
 
 THE REGULATOR. 
 
 a cylindrical vessel — having the conical plug and flange pipe 
 similar to that before described — the pressure being varied 
 by weights as before. 
 
 Mr. Stevenson, of Halifax, has placed several of these on 
 mains, and he speaks very highly of their efficiency. 
 
 THE REGULATOR. 
 
 This instrument is precisely the same in its construction 
 and action as the governor ; but is considerably smaller, 
 being sometimes made only to supply one light, as for the 
 street lamps, or for establishments of any magnitude, as 
 private dwellings, shops, manufactories, &c. 
 
 There is considerable economy in private establishments 
 by employing the regulator, inasmuch as it diminishes the 
 pressure to the degree where the greatest amount of light 
 is obtained from a given quantity of gas ; it likewise equalises 
 any irregularities that may exist in the pressure from the 
 company’s mains, and prevents loss of gas and smoke. The 
 regulator is also very important for street lamps : it prevents 
 waste, and the burners being suitable, the maximum amount 
 of light is obtained from the gas. A metropolitan compan}^, 
 which uses these instruments generally to its public lights, 
 has set an excellent example ; and perhaps there is no place 
 anywhere better lighted than their district. 
 
 The street lamp regulators are indispensable wherever 
 there is a heavy pressure on the mains. The instruments 
 are sometimes made with a leather diaphragm, on the prin- 
 ciple already mentioned. They were first made by Mr. 
 Ford, of London ; Messrs. Wright, Sugg, and others, are 
 also manufacturers. Their cost is about 3s. 6d. each. 
 
 Another kind of regulator for street lamps and private 
 consumers is the “ Mercurial,” manufactured by Messrs. 
 Hulett and Co., London. This, in principle, is the same as 
 the water-governor, the difference being that mercury is 
 used to replace the water. These are, undoubtedly, more 
 durable than leather regulators, many of them having been 
 in operation thirteen years, without requiring the least 
 attention or repair, and are now, apparently, in as good 
 condition as when they were first fixed. 
 
EXPERIMENTS ON COAL GAS. 
 
 261 
 
 CHAPTER XIX. 
 
 EXPERIMENTS ON COAL GAS. ON THE INFLUENCE OF 
 
 TEMPERATURE AND BAROMETRIC PRESSURE ON GAS." — 
 
 MODES OF EXAMINING AND COMPARING GAS. TESTS 
 
 FOR IMPURITIES IN GAS. 
 
 For the perfect analysis of gases a high degree of chemical 
 knowledge is essential, and this subject forms in itself a very 
 important branch of chemical investigation. Into this we 
 do not propose to enter, but shall merely notice a few of 
 those simple operations which the manager of every estab- 
 lishment for the manufacture of gas should readily be able 
 to perform, in order to satisfy himself and others of the 
 value and purity of his gas, and to afford the means of 
 rectifying errors. 
 
 For this object it is proposed in this chapter to explain 
 the means of examining gas, by its weight or specific gravity, 
 by means of the photometer, and by the condensation of the 
 hydrocarbons ; and although there may be some repetition, it 
 is intended to give the various tests for ascertaining the 
 purity of gas. 
 
 Gas is materially affected by three causes, namely, the 
 temperature, and barometric pressure to which it is subjected, 
 which influence its volume ; and the amount of humidity 
 combined therewith, which influences its weight. Gas is 
 exceedingly elastic, and expands or contracts very sensibly 
 with every variation of temperature, this expansion or con- 
 traction being at the rate of -rid part for every degree of Fahr., 
 or at the rate of nearly 2 per cent, for 10°, or nearly 20 per 
 cent, for 100° difference of temperature to which it may be 
 subjected. Thus 100 feet of gas at 40°, when its temperature is 
 increased to 140°, expands and becomes nearly 120 feet; and 
 the temperature again being reduced to 40°, the gas assumes 
 its former volume. 
 
 This variation of volume is illustrated by partially filling 
 a common bladder w T itli gas or air (for they are alike in 
 volume, and possess the same properties of contracting and 
 expanding, according to temperature), the neck of the bladder 
 being well secured so that gas cannot escape, when, if it be 
 
262 
 
 EXPERIMENTS ON COAL GAS. 
 
 held before a fire, the heat expands the gas enclosed therein, 
 until the bladder becomes full and distended. If it be after- 
 wards allowed to cool, on the gas attaining its previous 
 temperature and volume, the bladder assumes its former 
 collapsed state. Therefore it is usual in strictly defining the 
 volume of gas to take a standard degree of temperature, 
 viz., 60° Fahr., to which the proper corrections are made. 
 Gas also contracts and expands by variations of the baro- 
 metric pressure, concerning which a few words may be said. 
 The air which surrounds our globe constituting our atmo- 
 sphere is as tangible as the water on its surface, and is esti- 
 mated to be from 40 to 45 miles high or thick. It is therefore 
 obvious that, like all matter having what is termed weight, 
 the air in the lowest parts, as at the surface of the earth, or 
 at the level of the sea, has to bear the weight of the whole 
 of the superincumbent mass above, so that at the lowest 
 point it is necessarily compressed and reduced proportion- 
 ably in bulk ; whilst on the top of high mountains, or when 
 ascending with a balloon, the thickness or weight of air being 
 diminished, the atmosphere in those places is subject to dimi- 
 nished compression, when it is expanded in proportion to the 
 elevation. Gas, following the same law T , is compressed or 
 expanded according to the elevation where it exists : thus, at 
 about five miles high, a given quantity expands to about twice 
 the volume it would possess at the level of the sea. Or, a 
 balloon containing 200 feet of gas at that elevation, when 
 reaching the earth would by reason of the superincumbent 
 pressure of the atmosphere be compressed into ' a space of 
 100 feet only. 
 
 There is also another influence, according to the ever- 
 varying state of the weather, whereby gas, in any given 
 locality, is rendered more or less compressed or compact. 
 
 These influences of the atmosphere are ascertained by 
 means of the barometer, which is illustrated in its simplest 
 form by taking a glass tube of about 33 inches long, having 
 a bore of or \ inch diameter ; this being closed at one end, 
 it is entirely filled with mercury. A cup containing a por- 
 tion of mercury being at hand, the open end of the tube 
 is firmly closed by the finger, when the tube is inverted and 
 
ON WEIGHING GAS. 
 
 263 
 
 held perfectly vertical, and the end immersed in the mercury 
 contained in the cup, when, on the finger being removed, 
 the column of mercury falls to a point according to the 
 weather or the elevation of the locality where the operation 
 is conducted. Under ordinary circumstances, the distance 
 between the level of the mercury in the cup, and the top of 
 column, is 30 inches, which is the standard of comparison for 
 gas, which column is supported entirely by the pressure of 
 the atmosphere. If we suppose the tube and the cup to be 
 fixed, with a scale of inches and tenths of inches attached 
 to indicate the height of the mercury, then we realise the 
 construction of the barometer. By these means the degree 
 of compression that gas is subjected to is known, and the 
 proper corrections made to arrive at the given standard. 
 The increase or decrease of volume is about -o^woth parts 
 every variation of one-tenth of an inch of mercury. 
 
 As examples of the necessity of these corrections, a 
 volume of gas, when the mercury in the barometer is 31 
 inches, occupying 1,000 cubic feet, the barometer being 28 
 inches, would expand to 1,100 feet, or a difference of 10 per 
 cent. The city of Madrid is about 2,000 feet above the 
 level of the sea, and owing to the diminished pressure of the 
 atmosphere, the yield of gas from a given quantity of coal 
 averages there about 8 per cent, more in volume than would 
 be obtained under precisely similar circumstances in a works 
 nearly on a level with the sea. 
 
 The moisture in gas can be readily understood by our 
 every-day experience of its presence in the air, and it is 
 almost needless to state that this moisture increases very 
 considerably the weight of gas. 
 
 With these preliminary observations we will proceed to 
 describe the means of ascertaining the specific gravity or 
 weight of gas, which is always defined by comparison with 
 a like quantity of air ; this being assumed equal to 1,000, 
 the weight of a like quantity of gas under examination 
 being known, its specific gravity is determined ; thus, if a 
 given quantity of air weighs 1,000 grains, and the same 
 quantity of gas weighs only 470 grains, then the specific 
 gravity of the gas under examination will be 470 
 
2CA 
 
 ON WEIGHING GAS. 
 
 ON WEIGHING GAS. 
 
 A method of weighing gas is to exhaust a globe of known 
 capacity, such as are sold by philosophical instrument makers, 
 fitted with a cap and stop-cock for the purpose. By means 
 of an air-pump the globe is exhausted of all the air it contains, 
 when it is very accurately weighed ; this done, it is filled 
 with the gas under examination, and re-weighed, when the 
 difference between the weight of the globe when empty and 
 when filled with gas will of course be the weight of the gas. 
 In defining the value of gas, or ascertaining its specific 
 gravity, it is always compared with a certain quantity of 
 atmospheric air, as stated of a mean temperature of 60° Fahr. 
 and barometric pressure of 30 inches ; under these conditions 
 100 cubic inches of air weigh 31*017 grains. Whatever be 
 the capacity of the globe, the weight of 100 cubic inches of 
 the gas can be readily calculated when the weight of its con- 
 tents are known. Then as 100 cubic inches of air of mean 
 temperature and pressure weigh 31*017 grains, say as 31*017 
 i3 to the weight of 100 cubic inches of the gas, so is unity, 
 or the specific gravity of air, to the specific gravity of the 
 gas. Or another method may be adopted, which is indepen- 
 dent of the capacity of the globe, and does not require that 
 capacity to be determined at all. Weigh the globe when 
 filled with gas, also when filled with air, and when exhausted ; 
 from these three separate weights, that of the air contained 
 in the globe may be ascertained as well as that of the gas which 
 it contains. Then the weight of the gas divided by that of the 
 air is equal to the specific gravity. In performing the opera- 
 tion of weighing gases, however, many precautions are neces- 
 sary, and many niceties of manipulation must be practised ; 
 for instance, the gas must be reduced to mean pressure and 
 temperature, and corrections must also be made for moisture 
 both in the gas and the air, unless the gas has been pre- 
 viously dried, which is now the practice of the best chemists. 
 
 The accompanying table, by the late Mr. Wright, gives 
 the corrections for the bulk, or volume, of gas under various 
 degrees of pressure and temperature, the standard adopted 
 being barometric pressure of 30 inches, and temperature of 
 60°, which on reference is 1,000. First, referring to the 
 pressure, we find by this table that 933 feet of gas at 30 
 
ON WEIGHING GAS. 
 
 265 
 
 inches would expand and become 1,000 feet when the baro- 
 meter is at 28 inches, or 1,033 feet of gas at standard would 
 be compressed into 1,000 feet when the pressure of the 
 barometer was 31 inches. 
 
 Then as regards temperature, it would require 1,058 feet 
 of gas of standard temperature to occupy the space of 1,000 
 feet when the thermometer is at 32°. Or 944 feet of gas at 60° 
 would become expanded to 1,000 feet when the temperature 
 becomes 90°. Therefore the table is of the greatest import- 
 ance in determining the precise value of gas under all the 
 ordinary variations of pressure and temperature. 
 
 Mr. Wright also contrived an ingenious apparatus for 
 taking the specific gravity of gas by means of a balloon 
 capable of containing when full 1,000 cubic inches of gas. 
 This is sometimes gauged by a ring, so to limit the size of 
 the balloon, but a more accurate way is to measure the gas 
 through a good dry meter (the wet meter being objectionable 
 on account of the moisture therefrom intermixing with the 
 gas), when the specific gravity can be ascertained with 
 remarkable accuracy. 
 
 There is great prejudice against the use of dry meters for 
 experimental purposes, arising from the supposition that they 
 are not capable of measuring very small particles ; this, how- 
 ever, is erroneous, as a well-constructed dry meter should 
 measure the most minute quantity with the greatest accuracy. 
 
 The following are Mr. Wright’s directions for performing 
 the experiment, with the table which he has compiled for 
 correcting the temperature and pressure of the gas accord- 
 ing to the standard generally made use of, as already stated. 
 
 Expel the air from the balloon by folding in the form in 
 which it is first received, ascertain the weight of the balloon 
 and car, fill the balloon with gas, insert the stopper, and put 
 as many grains * in the car as will balance it in the air ; adc 
 the number of grains which it carries to the weight of the 
 balloon, and deduct the amount from the tabular number 
 corresponding to the degree of temperature indicated by 
 the thermometer, and the pressure indicated by the baro- 
 
 * The weights used are not troy grains, 100 of them being equal to 
 30*5 grains troy. They are each equal to a cubic foot of air, when 
 the barometer is at 30 inches, and thermometer at 60°. 
 
266 
 
 ON WEIGHING GAS. 
 
 meter; divide the result by the tabular number due to the 
 temperature and pressure of the gas, to ascertain which allow 
 the gas to blow upon the bulb of the thermometer until the 
 mercury is stationary, and the three first figures are the 
 specific gravity. 
 
 Example 1. 
 
 £ss£? °' ““ Si’s: j T > bni " »«»>■« «• 
 
 Temperature of gas . 56° \ 
 
 Barometer always the > Tabular number 958. 
 same as air . . 28 ’5 in. ) 
 
 Weight of balloon and grains in car, 560. 
 
 932 Tabular number for the air. 
 
 560 Weight of balloon, &c. 
 
 Tabular number for the gas 958)3720(388 Specific gravity. 
 
 2874 
 
 8460 
 
 7664 
 
 7960 
 
 7664 
 
 296 
 
 Example 2. 
 
 2335 ? ? lh * 
 
 Temperature of gas . 62° J 
 
 Barometer always the > Tabular number 1013. 
 same as air . . 30 5 in. ) 
 
 Weight of balloon and grains in car, 560. 
 
 1058 Tabular number for the air. 
 560 Weight of balloon, &c. 
 
 Tabular number for the gas 1013)4980(491 Specific gravity. 
 
 4052 
 
 9280 
 
 9117 
 
 1630 
 
 1013 
 
 617 
 
 Note. — This table will also be found convenient for correcting the 
 quantity of gas made, as indicated by the station meter ; the quantity, 
 being divided by the tabular number due to the temperature and 
 pressure, will give the amount as if the gas bad been at 60° Fahrenheit 
 and 30 inches barometer. 
 
ON WEIGHING GAS. 
 
 2G7 
 
 TABLE 
 
 POIl CORRECTIONS OP TEMPERATURE AND PRESSURE OF GAS. 
 
 BAR. 
 
 THER. 
 
 32 ° 
 
 o 
 
 CO 
 
 36 ° 
 
 38 ° 
 
 o 
 
 O 
 
 to 
 
 o 
 
 44 ° 
 
 46 ° 
 
 00 
 
 o 
 
 o 
 
 O 
 
 to 
 
 28-0 
 
 98 8 
 
 984 
 
 980 
 
 976 
 
 971 
 
 968 
 
 964 
 
 960 
 
 956 
 
 952 
 
 28-1 
 
 991 
 
 987 
 
 983 
 
 979 
 
 975 
 
 971 
 
 967 
 
 963 
 
 959 
 
 955 
 
 28-2 
 
 995 
 
 991 
 
 987 
 
 983 
 
 979 
 
 975 
 
 971 
 
 967 
 
 963 
 
 959 
 
 28*3 
 
 998 
 
 994 
 
 990 
 
 986 
 
 982 
 
 978 
 
 974 
 
 970 
 
 966 
 
 962 
 
 28*4 
 
 1002 
 
 998 
 
 993 
 
 990 
 
 985 
 
 981 
 
 977 
 
 973 
 
 970 
 
 966 
 
 28*5 
 
 1005 
 
 1001 
 
 997 
 
 993 
 
 989 
 
 985 
 
 981 
 
 977 
 
 973 
 
 969 
 
 28-6 
 
 1009 
 
 1005 
 
 1000 
 
 996 
 
 992 
 
 988 
 
 984 
 
 980 
 
 976 
 
 972 
 
 28*7 
 
 1012 
 
 1008 
 
 1004 
 
 1000 
 
 996 
 
 992 
 
 988 
 
 984 
 
 980 
 
 976 
 
 28-8 
 
 1016 
 
 1012 
 
 1008 
 
 1003 
 
 999 
 
 995 
 
 991 
 
 987 
 
 983 
 
 979 
 
 28-9 
 
 1020 
 
 1015 
 
 1011 
 
 1007 ' 
 
 1003 
 
 999 
 
 995 
 
 991 
 
 987 
 
 983 
 
 29-0 
 
 1023 
 
 1019 
 
 1015 
 
 1010 
 
 1006 
 
 1002 
 
 998 
 
 994 
 
 990 
 
 986 
 
 29*1 
 
 1027 
 
 1022 
 
 1018 
 
 1014 
 
 1010 
 
 1006 
 
 1002 
 
 998 
 
 993 
 
 989 
 
 29-2 
 
 1030 
 
 1026 
 
 1022 
 
 1017 
 
 1013 
 
 1009 
 
 1005 
 
 1001 
 
 997 
 
 993 
 
 29-3 
 
 1034 
 
 1029 
 
 1025 
 
 1021 
 
 1017 
 
 1012 
 
 1008 
 
 1004 
 
 1000 
 
 996 
 
 29-4 
 
 1037 
 
 1033 
 
 1029 
 
 1024 
 
 1020 
 
 1016 
 
 1012 
 
 1008 
 
 1004 
 
 1000 
 
 29-5 
 
 1041 
 
 1036 
 
 1032 
 
 1028 
 
 1024 
 
 1019 
 
 1015 
 
 1011 
 
 1007 
 
 1003 
 
 29-6 
 
 1044 
 
 1040 
 
 1036 
 
 1031 
 
 1027 
 
 1023 
 
 1019 
 
 1015 
 
 1010 
 
 1006 
 
 29-7 
 
 1048 
 
 1043 
 
 1039 
 
 1035 
 
 1031 
 
 1026 
 
 1022 
 
 1018 
 
 1014 
 
 1010 
 
 29*8 
 
 1051 
 
 1047 
 
 1043 
 
 1038 
 
 1034 
 
 1030 
 
 1026 
 
 1022 
 
 1017 
 
 1013 
 
 29'9 
 
 1055 
 
 1050 
 
 1046 
 
 1042 
 
 1038 
 
 1033 
 
 1029 
 
 1025 
 
 1021 
 
 1017 
 
 30-0 
 
 1058 
 
 1054 
 
 1050 
 
 1045 
 
 1041 
 
 1037 
 
 1033 
 
 1028 
 
 1024 
 
 1020 
 
 30-1 
 
 1062 
 
 1057 
 
 1053 
 
 1049 
 
 1044 
 
 1040 
 
 1036 
 
 1032 
 
 1028 
 
 1023 
 
 30*2 
 
 1065 
 
 1061 
 
 1057 
 
 1052 
 
 1048 
 
 1044 
 
 1039 
 
 1035 
 
 1031 
 
 1027 
 
 30*3 
 
 1069 
 
 1064 
 
 1060 
 
 1056 
 
 ]051 
 
 1047 
 
 1043 
 
 1039 
 
 1034 
 
 1030 
 
 30-4 
 
 1072 
 
 1068 
 
 r 064 
 
 1059 
 
 1055 
 
 1051 
 
 1046 
 
 1042 
 
 1038 
 
 1034 
 
 30-5 
 
 1076 
 
 1071 
 
 1067 
 
 1063 
 
 1058 
 
 1054 
 
 1050 
 
 1045 
 
 1041 
 
 1037 
 
 30-6 
 
 1079 
 
 1075 
 
 1071 
 
 1066 
 
 1062 
 
 1057 
 
 1053 
 
 1049 
 
 1045 
 
 1040 
 
 30*7 
 
 1083 
 
 1079 
 
 1074 
 
 1070 
 
 1065 
 
 1061 
 
 1057 
 
 1052 
 
 1048 
 
 1044 
 
 30-8 
 
 1087 
 
 1082 
 
 1078 
 
 1073 
 
 1069 
 
 1064 
 
 1060 
 
 1056 
 
 1051 
 
 1047 
 
 30-9 
 
 1090 
 
 1086 
 
 1081 
 
 1077 
 
 1072 
 
 1068 
 
 1063 
 
 1059 
 
 1055 
 
 1051 
 
 31-0 
 
 1094 
 
 1089 
 
 1085 
 
 1080 
 
 1076 
 
 1071 
 
 1067 
 
 1063 
 
 1058 
 
 1054 
 
 N 2 
 
268 
 
 ON WEIGHING GAS, 
 
 TABLE 
 
 FOR CORRECTIONS OF TEMPERATURE AND PRESSURE OF GAS 
 
 ( continued ). 
 
 RAR. 
 
 THER. 
 
 52° 
 
 54° 
 
 56° 
 
 or 
 
 oo 
 
 60° 
 
 62° 
 
 64° 
 
 66° 
 
 68° 
 
 70° 
 
 28-0 
 
 948 
 
 944 
 
 941 
 
 . 937 
 
 933 
 
 930 
 
 926 
 
 922 
 
 919 
 
 915 
 
 28T 
 
 952 
 
 948 
 
 944 
 
 940 
 
 937 
 
 933 
 
 929 
 
 926 
 
 922 
 
 919 
 
 28:2 
 
 955 
 
 951 
 
 947 
 
 944 
 
 940 
 
 936 
 
 933 
 
 929 
 
 925 
 
 922 
 
 28-3 
 
 958 
 
 955 
 
 951 
 
 947 
 
 943 
 
 940 
 
 936 
 
 932 
 
 929 
 
 925 
 
 28*4 
 
 962 
 
 958 
 
 954 
 
 950 
 
 947 
 
 943 
 
 939 
 
 936 
 
 932 
 
 928 
 
 28-5 
 
 965 
 
 961 
 
 958 
 
 954 
 
 950 
 
 946 
 
 943 
 
 939 
 
 935 
 
 932 
 
 28*6 
 
 969 
 
 965 
 
 961 
 
 957 
 
 953 
 
 950 
 
 946 
 
 942 
 
 939 
 
 935 
 
 28-7 
 
 972 
 
 968 
 
 964 
 
 960 
 
 957 
 
 953 
 
 949 
 
 945 
 
 942 
 
 938 
 
 28*8 
 
 975 
 
 971 
 
 968 
 
 964 
 
 960 
 
 956 
 
 952 
 
 949 
 
 945 
 
 941 
 
 28-9 
 
 979 
 
 975 
 
 971 
 
 967 
 
 963 
 
 960 
 
 956 
 
 952 
 
 948 
 
 944 
 
 29*0 
 
 982 
 
 978 
 
 974 
 
 970 
 
 967 
 
 963 
 
 959 
 
 955 
 
 952 
 
 948 
 
 29*1 
 
 985 
 
 982 
 
 978 
 
 974 
 
 970 
 
 966 
 
 962 
 
 959 
 
 955 
 
 951 
 
 29-2 
 
 989 
 
 985 
 
 981 
 
 977 
 
 973 
 
 969 
 
 966 
 
 962 
 
 958 
 
 954 
 
 29-3 
 
 992 
 
 988 
 
 984 
 
 981 
 
 977 
 
 973 
 
 969 
 
 965 
 
 961 
 
 957 
 
 29-4 
 
 996 
 
 992 
 
 988 
 
 984 
 
 980 
 
 976 
 
 972 
 
 969 
 
 965 
 
 961 
 
 29-5 
 
 999 
 
 995 
 
 991 
 
 987 
 
 983 
 
 979 
 
 976 
 
 972 
 
 968 
 
 964 
 
 29-6 
 
 1002 
 
 998 
 
 994 
 
 991 
 
 987 
 
 983 
 
 979 
 
 975 
 
 971 
 
 968 
 
 29*7 
 
 1006 
 
 1002 
 
 998 
 
 994 
 
 990 
 
 986 
 
 982 
 
 978 
 
 975 
 
 971 
 
 29-8 
 
 1009 
 
 1005 
 
 1001 
 
 997 
 
 993 
 
 989 
 
 986 
 
 982 
 
 978 
 
 974 
 
 29-9 
 
 1013 
 
 1009 
 
 1005 
 
 1001 
 
 997 
 
 993 
 
 989 
 
 985 
 
 981 
 
 978 
 
 30-0 
 
 1016 
 
 1012 
 
 1008 
 
 1004 
 
 1000 
 
 996 
 
 992 
 
 988 
 
 984 
 
 981 
 
 30-1 
 
 1019 
 
 1015 
 
 1011 
 
 1007 
 
 1003 
 
 999 
 
 995 
 
 992 
 
 988 
 
 984 
 
 30-2 
 
 1023 
 
 1019 
 
 1015 
 
 1011 
 
 1007 
 
 1003 
 
 999 
 
 995 
 
 991 
 
 987 
 
 30*3 
 
 1026 
 
 1022 
 
 1018 
 
 1014 
 
 1010 
 
 1006 
 
 100£ 
 
 998 
 
 994 
 
 990 
 
 30-4 
 
 1029 
 
 1025 
 
 1021 
 
 1017 
 
 1013 
 
 1009 
 
 1005 
 
 1002 
 
 998 
 
 994 
 
 30-5 
 
 1033 
 
 1029 
 
 1025 
 
 1021 
 
 1017 
 
 1013 
 
 1009 
 
 1005 
 
 1001 
 
 997 
 
 30-6 
 
 1036 
 
 1032 
 
 1028 
 
 1024 
 
 1020 
 
 1016 
 
 1012 
 
 1008 
 
 1004 
 
 1000 
 
 30-7 
 
 1040 
 
 1036 
 
 1031 
 
 1027 
 
 1023. 
 
 1019 
 
 1015 
 
 1011 
 
 1007 
 
 1004 
 
 30-8 
 
 1043 
 
 1039 
 
 1035 
 
 1031 
 
 1027 
 
 1023 
 
 1019 
 
 1015 
 
 1011 
 
 1007 
 
 30-9 
 
 1046 
 
 1043 
 
 1038 
 
 1034 
 
 1030 
 
 1026 
 
 1022 
 
 1018 
 
 1014 
 
 1010 
 
 31*0 
 
 1050 
 
 1046 
 
 1042 
 
 1037 
 
 1033 
 
 1029 
 
 1025 
 
 1021 
 
 1017 
 
 1013 
 
ON WEIGHING GAS. 
 
 269 
 
 TABLE 
 
 FOR CORRECTIONS OF TEMPERATURE AND PRESSURE OF GAS 
 [continued). 
 
 BAR. 
 
 THER. 
 
 72° 
 
 740 
 
 76° 
 
 78° 
 
 0 
 
 0 
 
 CO 
 
 82° 
 
 84° 
 
 86° 
 
 0 
 
 00 
 
 CO 
 
 1 
 
 90° 
 
 28*0 
 
 912 
 
 908 
 
 905 
 
 901 
 
 898 
 
 895 
 
 891 
 
 888 
 
 885 
 
 881 
 
 28T 
 
 915 
 
 912 
 
 908 
 
 905 
 
 901 
 
 898 
 
 894 
 
 891 
 
 888 
 
 884 
 
 28*2 
 
 918 
 
 915 
 
 911 
 
 908 
 
 904 
 
 901 
 
 898 
 
 894 
 
 891 
 
 888 
 
 28-3 
 
 922 
 
 918 
 
 914 
 
 911 
 
 908 
 
 904 
 
 901 
 
 897 
 
 894 
 
 891 
 
 28*4 
 
 925 
 
 921 
 
 918 
 
 914 
 
 911 
 
 907 
 
 904 
 
 900 
 
 897 
 
 894 
 
 28*5 
 
 928 
 
 925 
 
 921 
 
 917 
 
 914 
 
 910 
 
 907 
 
 904 
 
 900 
 
 897 
 
 28-6 
 
 931 
 
 928 
 
 924 
 
 921 
 
 917 
 
 914 
 
 910 
 
 907 
 
 903 
 
 900 
 
 287 
 
 935 
 
 931 
 
 927 
 
 924 
 
 920 
 
 917 
 
 913 
 
 910 
 
 907 
 
 903 
 
 28*8 
 
 938 
 
 934 
 
 931 
 
 927 
 
 924 
 
 920 
 
 917 
 
 913 
 
 910 
 
 906 
 
 28-9 
 
 941 
 
 937 
 
 934 
 
 930 
 
 927 
 
 923 
 
 920 
 
 916 
 
 913 
 
 910 
 
 29*0 
 
 944 
 
 941 
 
 937 
 
 934 
 
 930 
 
 926 
 
 923 
 
 919 
 
 916 
 
 913 
 
 29T 
 
 948 
 
 944 
 
 940 
 
 937 
 
 933 
 
 930 
 
 926 
 
 923 
 
 919 
 
 916 
 
 29*2 
 
 951 
 
 947 
 
 944 
 
 940 
 
 936 
 
 933 
 
 929 
 
 926 
 
 922 
 
 919 
 
 29-3 
 
 954 
 
 950 
 
 947 
 
 943 
 
 940 
 
 936 
 
 933 
 
 929 
 
 926 
 
 922 
 
 29*4 
 
 957 
 
 954 
 
 950 
 
 946 
 
 943 
 
 939 
 
 936 
 
 932 
 
 929 
 
 925 
 
 29-5 
 
 961 
 
 957 
 
 
 950 
 
 946 
 
 942 
 
 939 
 
 935 
 
 932 
 
 928 
 
 29*6 
 
 964 
 
 960 
 
 957 
 
 953 
 
 949 
 
 946 
 
 942 
 
 939 
 
 935 
 
 932 
 
 29*7 
 
 967 
 
 963 
 
 960 
 
 956 
 
 952 
 
 949 
 
 945 
 
 942 
 
 938 
 
 935 
 
 29-8 
 
 970 
 
 967 
 
 963 
 
 959 
 
 956 
 
 952 
 
 948 
 
 945 
 
 941 
 
 938 
 
 29*9 
 
 974 
 
 970 
 
 966 
 
 963 
 
 959 
 
 955 
 
 952 
 
 948 
 
 944 
 
 941 
 
 30-0 
 
 977 
 
 973 
 
 969 
 
 966 
 
 962 
 
 958 
 
 955 
 
 951 
 
 948 
 
 944 
 
 30-1 
 
 980 
 
 976 
 
 973 
 
 969 
 
 965 
 
 962 
 
 958 
 
 954 
 
 951 
 
 947 
 
 30-2 
 
 983 
 
 980 
 
 976 
 
 972 
 
 969 
 
 965 
 
 961 
 
 958 
 
 954 
 
 950 
 
 30*3 
 
 987 
 
 983 
 
 979 
 
 975 
 
 972 
 
 968 
 
 964 
 
 961 
 
 957 
 
 954 
 
 30-4 
 
 990 
 
 986 
 
 982 
 
 979 
 
 975 
 
 971 
 
 968 
 
 964 
 
 960 
 
 957 
 
 30-5 
 
 993 
 
 989 
 
 986 
 
 982 
 
 978 
 
 974 
 
 971 
 
 967 
 
 963 
 
 960 
 
 30-6 
 
 996 
 
 993 
 
 989 
 
 985 
 
 981 
 
 978 
 
 974 
 
 970 
 
 967 
 
 963 
 
 30-7 
 
 1000 
 
 996 
 
 992 
 
 988 
 
 985 
 
 981 
 
 977 
 
 973 
 
 970 
 
 966 
 
 30-8 
 
 1003 
 
 999 
 
 995 
 
 991 
 
 988 
 
 984 
 
 980 
 
 977 
 
 973 
 
 970 
 
 30*9 
 
 1006 
 
 1002 
 
 998 
 
 995 
 
 991 
 
 987 
 
 984 
 
 980 
 
 976 
 
 973 
 
 31*0 
 
 1009 
 
 1006 
 
 1002 
 
 998 
 
 994 
 
 990 
 
 987 
 
 983 
 
 979 
 
 976 
 
270 
 
 CORRECTIONS FOR MOISTURE IN GAS. 
 
 The preceding table contains no correction for moisture, 
 nor is this commonly considered necessary in practice if the 
 experiments are made in a dry room at some distance from 
 the gasholder, or vessel in which the gas has been standing 
 over water ; nevertheless a few words will be said on the 
 subject, so that if desirable the proper corrections may be 
 made. 
 
 CORRECTIONS FOR MOISTURE IN GAS. 
 
 It has been ascertained by careful experiments that 100 
 cubic inches of permanent aqueous vapour, corrected for a 
 temperature of 60° and a mean pressure of 30 inches, weigh 
 19*29 grains. If we then know the proportion of aqueous 
 vapour absorbed by gas at different temperatures when in 
 direct contact with water, we shall have the means of deter- 
 mining, from the known volume and weight of the moist 
 gas, the volume and weight of the dry gas. Professor 
 Faraday, in his “ Chemical Manipulations/’ gives the follow- 
 ing table, which is founded on the experiments of Dr. Dalton 
 and Dr. Ure, and which ranges through most of the tempe- 
 ratures at which gas is likely to be weighed : — 
 
 Table showing the Proportion by Volume op Aqueous Vapour 
 
 EXISTING IN ANY GrAS STANDING OYER OR IN CONTACT WITH 
 
 "Water at the corresponding Temperatures, and at a mean 
 
 Barometric Pressure of 30 inches. 
 
 Temp. 
 
 Proportion 
 of vapour 
 in 1 volume 
 of gas. 
 
 Temp. 
 
 Proportion 
 of vapour 
 in 1 volume 
 of gas. 
 
 i . 
 
 Temp. 
 
 Proportion 
 cf vapour 
 in I volume 
 of gas. 
 
 deg. 
 
 40 
 
 •00933 
 
 deg. 
 
 54 
 
 •01533 
 
 deg. 
 
 68 
 
 .02406 
 
 41 
 
 •00973 
 
 55 
 
 *01586 
 
 69 
 
 •02483 
 
 42 
 
 •01013 
 
 56 
 
 •01640 
 
 70 
 
 •02566 
 
 43 
 
 •01053 
 
 57 
 
 •01693 
 
 71 
 
 •02653 
 
 44 
 
 •01093 
 
 58 
 
 •01753 
 
 72 
 
 •02740 
 
 45 
 
 •01133 
 
 59 
 
 •01810 
 
 73 
 
 •02830 
 
 46 
 
 •01173 
 
 60 
 
 •01866 
 
 74 
 
 •02923 
 
 47 
 
 •01213 
 
 61 
 
 •01923 
 
 75 
 
 •03020 
 
 48 
 
 •01253 
 
 62 
 
 •01980 
 
 76 
 
 •03120 
 
 49 
 
 •01293 
 
 63 
 
 •02000 
 
 77 
 
 •03220 
 
 50 
 
 •01333 
 
 64 
 
 •02120 
 
 78 
 
 •03323 
 
 51 
 
 •01380 
 
 65 
 
 •02190 
 
 79 
 
 •03423 
 
 52 
 
 •01426 
 
 66 
 
 •02260 
 
 80 
 
 •03533 
 
 53 
 
 •01480 
 
 67 
 
 •02330 
 
 
 
CORRECTIONS FOR MOISTURE IN GAS. 
 
 271 
 
 It is easy from this table to determine the quantity or 
 aqueous vapour present in gas of any given temperature 
 which is standing over water, or which has been in contact 
 with water ; for it is only necessary to multiply the volume 
 of the moist gas by the number corresponding to the tem- 
 perature, in order to find the volume of aqueous vapour which 
 is present. 
 
 Suppose 120 cubic inches of moist gas at a temperature of 
 70° weighing 22 grains under mean barometric pressure, then 
 the volume of vapour present is equal to 120 X *02566 = 3*079 
 cubic inches. This volume corrected to a temperature of 
 60° will have to be deducted from the whole volume of gas 
 corrected to the same temperature. 
 
 Now 120 cubic inches at 70° are equal to 
 
 120 x 
 
 460 + 60 
 460 + 70 
 
 117*74' cubic inches at a temperature 
 
 of 
 
 60°. Hence 117*74 — 3*079 = 114*66 cubic inches, the 
 volume of dry gas at mean temperature. Then to find the 
 weight of this volume of dry gas w^e must de-duct from the 
 whole weight of 22 grains the weight of 3*079 cubic inches 
 of aqueous vapour, which is equal to 3*079 X *1929 = *5939 
 grains. Hence we have 22* — *5939 = 21*4061 grains as 
 the weight of 114*66 cubic inches of dry gas. From this it 
 follows by simple proportion that 100 cubic inches of the 
 dry gas corrected for temperature and moisture will weigh 
 
 21-4061 X 100 
 114*66 
 
 18*67 grains. 
 
 Then as 100 cubic inches of air at mean temperature and 
 pressure weigh 31 grains, the specific gravity of the gas 
 will be 
 
 18*67 
 
 31 
 
 = *602. 
 
 There are some advantages in operating on the moist gas, 
 because the volume can be measured before passing it into 
 the globe in which it is weighed ; and in this case no error 
 will be made even if the globe be not perfectly exhausted,. 
 
272 
 
 CORRECTIONS FOR MOISTURE IN GAS. 
 
 or if the globe be not quite filled with gas, the only thing 
 necessary being the increase of weight due to the gas actually 
 admitted as measured by a graduated jar before transferring 
 it to the globe. This measurement cannot so perfectly be 
 made when the gas is dried beforehand, in which case the 
 globe must be perfectly exhausted and perfectly filled with 
 gas, when, its capacity being known, the specific gravity can 
 be arrived at as before. 
 
 The simplest method of drying gas is to pass it through a 
 tube filled with some substance having a powerful attraction 
 for water. The tubes used are about half an inch in diameter, 
 and from 12 to 20 inches long. Chloride of lime will answer 
 well as a desiccating material for gas which does not 
 contain much ammonia. The chloride of lime should be 
 heated and fused in an earthenware crucible, a temperature 
 below that of visible redness being quite sufficient for the 
 purpose; then poured upon a clean metallic or stone surface, 
 and, as soon as it has solidified, broken up and put into 
 stopped bottles. This chloride being divided into a mixture 
 of large and small fragments is to be introduced rapidly into 
 the tube, until the latter is nearly full ; the apparatus is then 
 ready for use. 
 
 The tube may be connected with the jar, gasholder, or 
 other vessel containing or evolving the gas, or in any con- 
 venient way ; and so much gas should be passed through as 
 effectually to expel all the common air before the globe or 
 vessel to be filled with the dry gas be attached. That being 
 lone, the gas should be allowed to pass slowly, 100 cubical 
 inches having from 10 to 20 minutes allowed for pass- 
 ing through such a tube as that described, though if tho 
 period be lengthened no injury is occasioned. If the tube 
 be of smaller diameter, more time should be proportionably 
 allowed. 
 
 Chloride of lime will not answer for ammonia, or for sul- 
 phurous and some other acid gases. Potash, or carbonate 
 of potash, answers perfectly well for ammonia, but not for 
 acid gases. Sulphuric acid is a very excellent desiccant for 
 many gases, and may be used in a tube by first curving 
 the tube, then filling it with fragments of glass or rock 
 
ON THE BROMINE TEST. 
 
 273 
 
 crystal, and afterwards pouring in so much concentrated 
 oil of vitriol as shall moisten the fragments but not cause 
 obstruction to the passage of the gas. By moving the tube 
 a little from time to time the acid is made to pass from place 
 to place ; it becomes mixed, and it remoistens the fragments, 
 which from the previous quiescent state of the apparatus 
 may have drained considerably. This substance is effectual 
 with almost all ordinary gases except ammonia.* 
 
 ON THE BROMINE TEST. 
 
 There are substances which possess the property of reducing 
 certain gases to a liquid state, — thus a solution of potash 
 absorbs carbonic acid ; the solution of the acetate of lead 
 absorbs sulphuretted hydrogen ; and chlorine and bromine 
 condense the hydrocarbons existing in gas. Therefore, if a 
 suitable graduated tube be employed, the volume of gas 
 absorbed or condensed is known by the diminished volume 
 of the mass. On this principle the means of ascertaining 
 the quantity of olefiant gas, or hydrocarbons existing in 
 gas, are determined, and its quality as an illuminating agent, 
 under some circumstances, may be defined. 
 
 The method of ascertaining the amount of condensation 
 produced in coal gas by the addition of a single drop of 
 bromine, is now much preferred to the use of chlorine, which 
 presented some difficulties in estimating the volumes to be 
 mixed. 
 
 The chlorine test, however, in the hands of a skilful ope- 
 rator, is a very beautiful experiment. It requires one mea- 
 sure of chlorine gas to be passed into a jar inverted over 
 water, and containing two measures of coal gas. This mix- 
 ture will cause a diminution of volume in the gas, and an 
 oily liquid will be formed by the hydrocarbons or olefiant 
 gas uniting with the chlorine. The chlorine ought to be in 
 excess ; and the remaining portion having been removed by 
 the addition of a few drops of a strong solution of potash, the 
 diminution of volume which the coal gas has sustained will 
 
 * Faraday’s “ Chemical Manipulations,” p. 390. 
 
 N 3 
 
274 
 
 ON THE BROMINE TEST. 
 
 be a measure of its value, by indicating the proportion of 
 olefiant gas contained in it. 
 
 For the purpose of testing gas with bromine a glass tube 
 is used about 3 feet long and half an inch diameter inside. 
 This is closed at one end and bent at the other into a small 
 semicircle, so that the straight part of the tube is about 
 33 inches long, the remaining 3 inches being occupied by 
 the bend. The straight part of the tube is graduated into 
 hundredths towards the closed end as far as twenty-five 
 divisions, or one-fourth of the length; this graduation serving 
 to show the diminution in the volume of gas effected by the 
 bromine. 
 
 The tube is to be filled with water, and the curved or open 
 end placed over an orifice from which the gas is allowed to 
 flow. After passing up through the water the gas begins to 
 displace the latter, and must be allowed to do so till the gas 
 exactly fills the tube from the zero division or the beginning 
 of the graduation to the top of the tube. The curved end 
 of the tube remains filled with water, which acts as a seal 
 and prevents the escape of gas. It is then necessary to add 
 a few drops of a solution of potash to remove any carbonic 
 acid which may be in the gas. A portion of bromine about 
 the size of a small pea is dropped into the open end of the 
 tube, and the thumb being placed firmly on this open end, 
 the tube is to be shaken several times in order to bring the 
 bromine into perfect contact with the gas. After this the 
 thumb may be withdrawn under water, and a few drops of a 
 solution of potash added, in order to remove from the tube 
 the vapour of bromine contained in it. To effect this removal 
 the thumb is to be again pressed on the open end of the 
 tube, and its contents agitated by again inverting the tube 
 once or twice. The open end of the tube is then to be 
 placed in water, which will now rise considerably above zero, 
 and after remaining at rest for some time, the height of the 
 water may be read off on the graduated part of the tube. 
 The division so read off will of course represent the conden- 
 sation of the gas in parts of 100. 
 
 Some of the inferior gases are not condensed by bromine 
 to the extent of more than 3 or 4 per cent, while some of 
 
ON THE COMPARISON OF GASES. 
 
 275 
 
 the rich and highly illuminating cannel coal gases are con- 
 densed as much as 30 per cent. 
 
 This process cannot, however, be regarded as satisfactory 
 under all conditions, inasmuch as it only gives the volume of 
 the hydrocarbons, without their density; and it follows that 
 if the one be considered without the other, the experiment 
 can have no value. 
 
 With caking-coal gas, each per centage of condensation 
 or diminished volume is considered equal to three candles, so 
 that 4 per cent, condensation would indicate twelve candles ; 
 but an admixture of cannel gas renders the experiment en- 
 tirely worthless. 
 
 Cannel gas, when examined by the process, gives no positive 
 result, without the specific gravity of the condensed matter be 
 ascertained, when, the volume and weight being known, the 
 value of the gas is determined. Therefore, under some circum- 
 stances, the bromine test cannot be relied on ; and, although 
 exceedingly beautiful in operation, it must give place to other 
 and more definite means of estimating the illuminating power 
 of gas. 
 
 ON THE COMPARISON OF GASES BY MEANS OF THE 
 PHOTOMETER. 
 
 The method of estimating the illuminating power of gases 
 in measures of which the unit is a single wax candle con- 
 suming a known weight of wax per hour, is a test of great 
 beauty and simplicity. By many of the most experienced 
 gas engineers this test of the value of a gas is preferred to all 
 other methods of comparison. It has been justly said that 
 the specific gravity of a gas is not a correct test of value, 
 because this may be due to the presence of carbonic acid ; 
 but when the actual lighting power is tried by the photo- 
 meter, if the standard should fall short of that which might 
 1 e expected from the specific gravity of the gas, then the 
 presence of carbonic acid may be fairly suspected. 
 
 The earliest method of comparing the lighting power of 
 gas with that of candles, or any other standard, was that pro- 
 posed by Count Rumford, and commonly known as the 
 method of shadows. For this purpose a simple apparatus was 
 
276 
 
 ON THE COMPARISON OF GASES. 
 
 designed, and named after its inventor, the Rumford pho- 
 tometer. This consists simply of a black box opened at each 
 end, which ends were presented to the two lights under ex- 
 amination. In this box a white space is painted to receive 
 the shadows made by intercepting the light from a gas-burner 
 and a candle, placed at such distances as to give shadows of 
 precisely the same intensity. When the distances are so 
 adjusted that the shadows are precisely similar in colour or 
 intensity, then the lighting powers of the two flames are 
 proportionate to the squares of their distances from the sub- 
 stance intercepting the light and throwing the shadow. Thus, 
 if the gas-burner be 9 feet and the candle 3 feet from the 
 centre of the photometer, the squares being 81 and 9, their 
 light will be in the proportion of these numbers to each other, 
 the gas giving the light of nine candles. Or if the gas 
 give a shadow equal to that of a candle placed at one-fourth 
 of the distance, it is equal to sixteen candles, and so on. In 
 general terms, let d be the distance from the candle to the 
 intercepting body of photometer, and x the distance from 
 the gas-burner to the same photometer, then when the 
 shadows are alike, the illuminating power of the gas is equal 
 to the square of x divided by the square of d , that of the 
 candle being unity. When the distance of the candle is 
 fixed at 10 inches, it will only be necessary to cut off two 
 figures from the square of the gas-burner’s distance to find 
 the number of candles to which the ,gas is equal. Hence 
 the distance of the gas-burner being 24 inches, while that of 
 the candle is 10 inches, then the square of 24 is equal to 
 576, and the light given by the gas is 5*76 candles. 
 
 Although the method of comparison by shadows is still 
 highly spoken of by some who have practised it for many 
 years, and have acquired a habit of great accuracy in dis- 
 criminating the depth of shadows, it is not in general use at 
 the present time, the Rumford photometer having been super- 
 seded by an instrument invented by Professor Bunsen, of 
 Marburg, and first introduced in this country by Dr. Lyon 
 Playfair, who described it to Mr. King, of Liverpool. The 
 comparison made by the Bunsen photometer is not one of 
 shadows, but is a comparison of transmitted light passing 
 
ON THE COMPARISON OF GASES. 
 
 277 
 
 through a transparent surface, with reflected light striking on 
 an opaque surface. This comparison is made by interposing 
 between two lights a disc of paper with an annular space 
 made transparent, and surrounding a small part in the centre 
 which is opaque. Now, if any light whatever be placed 
 behind a disc of this kind, the transparent ring will be illu- 
 minated, while a dark circle will appear in the centre. If 
 another light be now placed in front of the paper at such 
 a distance as to cause the reflection from the opaque circle 
 to be greater than that transmitted through the transparent 
 ring, the centre space will be more illuminated than the ring. 
 Again, if the light in front be placed at such a distance that 
 the reflection is less than the transmitted light, then the 
 central spot will appear darker than the ring, and be dis- 
 tinctly visible. When, however, the light is so placed that 
 the light reflected and that transmitted are exactly equal, 
 then the centre spot is invisible, as the whole surface of the 
 paper appears alike, and no difference is observed between 
 the central spot and the annular space which surrounds it. 
 When this condition is obtained the lights are to each other 
 as before, in the ratio of the squares of their distance from 
 the disc. 
 
 Photometers made on this principle of comparing lights 
 by means of a disc of this kind placed between them are 
 now made by Mr. Wright and Mr. Sugg, both of West- 
 minster, and by Messrs. Hulett and Company, who manu- 
 facture the photometers known as Church and Mann’s. 
 
 The composition at first used for making the paper trans- 
 parent was melted spermaceti, but Dr. Fyfe recommends 
 spermaceti dissolved in oil of naphtha till it acquires a con- 
 sistence which is solid at natural temperatures, but is liquefied 
 by the application of a very gentle heat, such as by holding 
 the vessel for a few minutes in the warm hand. He applies 
 the mixture when fluid, leaving in the centre a circle un- 
 covered about the size of half-a-crown. After this the paper 
 is held horizontally over a lamp, and very cautiously heated, 
 so as to make all the inequalities disappear. Dr. Fyfe 
 prefers the fine cream-coloured letter-paper for the purpose 
 of the disc. 
 
278 ON THE COMPARISON OF GASES. 
 
Fig. 66. 
 
 ON TIIE COMPARISON OF GASES, 
 
 279 
 
280 
 
 ON THE COMPARISON OF GASES. 
 
 Figs. 64 to 67 show the Bunsen photometer as constructed 
 by Mr. Wright. Fig. 64, drawn on a scale of -roth of the 
 full size, is an elevation of the photometer : a a is a straight 
 bar of wood carrying at one end a support for a candle, and at 
 the other a support for the gas-burner, which can be screwed 
 on when required. These supports are so placed that the 
 lights are exactly 100 inches apart from centre to centre. 
 Sometimes a meter is fixed at one end in place of the pillar e, 
 and the burner is screwed on to a short pipe which passes 
 up from the meter ; in other cases a flexible tube b is used 
 for conveying the gas to the burner after passing through 
 an experimental meter so made, that by an observation of a 
 minute the gas consumed in an hour is indicated : c is the 
 movable carrier supporting the disc, which can thus be placed 
 in any position on the bar : d is the centre of the bar from 
 which the divisions commence, the first division in the centre 
 being marked 1 for one candle. The bar is divided into a 
 scale towards the end where the candle is placed, which scale 
 indicates candles and tenths of a candle, as far as nine candles. 
 From 9 to 20 the spaces indicate half-candles, and from 20 
 to 36 they indicate only whole candles. 
 
 Fig. 65, on a scale of ±th the full size, is an elevation of a 
 blackened shade, which is placed over the disc in order to 
 exclude any radiated light, and render the determina- 
 tions on the disc more delicate. It consists of two short 
 wide tubes made slightly conical, and united at top by a 
 hinge, which allows them to be separated at the base. The 
 shade is open entirely through, in the direction of its axis, 
 and when placed over the disc, the surface of the latter is 
 seen by the observer through the small spaces a a in the 
 side of the shade. 
 
 Figs. 66 and 67, on a sc.ale of ^th the full size, are an eleva- 
 tion and side view of the disc and carrier. The disc is 
 merely a circle about 4 inches diameter, inserted between 
 two flat metal rings which are kept close by a small screw. 
 The opaque space in the centre b is an inch and a half in 
 diameter, and c is the transparent part surrounding it. In 
 these figures d is the carrier, e is the divided bar, and f the 
 pointer marking the division over which the disc stands. 
 
WEIGHT OF GAS FRODUCED FROM COAL. 281 
 
 The following table shows the distance on the scale of the 
 whole candles up to 30 candles ; the fractional parts may be 
 tolerably well ascertained by dividing the intermediate dis- 
 tance. 
 
 
 Distance of division 
 
 
 Distance of division 
 
 No. of candles. 
 
 from centre of candle. 
 Inches. 
 
 No. of candles. 
 
 from centre of candle. 
 Inches. 
 
 2 . . 
 
 
 41*42 
 
 17 . . 
 
 
 19-52 
 
 3 . . 
 
 
 . 36-61 
 
 18 . . 
 
 
 19-08 
 
 4 . . 
 
 
 . 33-34 
 
 19 . . 
 
 
 18-67 
 
 5 . . 
 
 
 . 30-90 
 
 20 . . 
 
 
 18-26 
 
 6 . . 
 
 
 . 28-99 
 
 21 . . 
 
 
 17-96 
 
 7 . . 
 
 
 , 27-43 
 
 22 . . 
 
 
 17-57 
 
 8 . . 
 
 
 , 26-12 
 
 23 . . 
 
 
 17-25 
 
 9 . . 
 
 
 , 25-00 
 
 24 . . 
 
 
 16-95 
 
 10 . . 
 
 
 . 24-14 
 
 25 . . 
 
 
 16-67 
 
 11 . . 
 
 
 . 23-16 
 
 26 . . 
 
 
 16-40 
 
 12 . . 
 
 
 . 22-40 
 
 27 . . 
 
 
 16-14 
 
 13 . . 
 
 
 . 21-71 
 
 28 . . 
 
 
 15-90 
 
 14 . . 
 
 
 , 21.09 
 
 29 . . 
 
 
 15-64 
 
 15 . . 
 
 16 . . 
 
 
 , 20-52 
 
 . 20-00 
 
 30 . . 
 
 
 15-41 
 
 The photometer made by Messrs. Hulett and Co., of 
 London, has the disc always fixed at a distance of 10 inches 
 from the candle ; this has the advantage that the beam being 
 shorter it is more portable and occupies less space in the 
 apartment where placed. 
 
 THE WEIGHT OF GAS PRODUCED FROM COAL. 
 
 In considering the quantity of gas produced from a ton 
 of coal, the real value is determined by its volume and its 
 specific gravity, so that the most convenient mode of ex- 
 pressing the quantity is to give the weight of the gas pro- 
 duced, this being a compound of the quantity and the specific 
 gravity. The latter being known, the following rule will 
 give the weight of any quantity. 
 
 Kule. — Multiply the quantity in feet by the specific 
 gravit}', and strike off the three right-hand figures, then 
 multiply the remainder by the decimal *0753, then strike off 
 the proper decimals, and the remainder is the weight in 
 pounds. Thus, if 100 lbs of coal give 400 cubic feet of 
 
282 TESTS FOR ASCERTAINING PURITY OF GAS. 
 
 gas, of specific gravity 420 — then 420 X 400 X *0753 = 
 12*G5 lbs. of gas. 
 
 The following comparison of the specific gravity of gas, 
 with the illuminating power as shown by candles, is an average 
 deduced from the results of the best experimenters : — 
 
 No. of candles. Specific gravity. 
 
 No. of candles. Specific gravity. 
 
 12 
 
 equal to 
 
 •400 
 
 26 
 
 equal to 
 
 •600 
 
 14 
 
 
 •425 
 
 28 
 
 ft 
 
 •640 
 
 16 
 
 >> 
 
 •450 
 
 30 
 
 tt 
 
 •670 
 
 18 
 
 >> 
 
 •475 
 
 32 
 
 ff 
 
 •700 
 
 20 
 
 j) 
 
 •500 
 
 34 
 
 tf 
 
 •730 
 
 22 
 
 it 
 
 •530 
 
 36 
 
 a 
 
 *770 
 
 24 
 
 tf 
 
 •560 
 
 
 
 
 For further details on the experiments on coal gas and 
 the mode of analysing, the reader is referred to the ‘‘Analysis 
 of Gas,” for practical men, by A. Wright. 
 
 ON TESTS FOR ASCERTAINING THE PURITY OF GAS. 
 
 The managers of many works unfortunately attach but 
 little importance to the purification of the gas they supply ; 
 and it is a lamentable fact that, notwithstanding the progress 
 which the science of gas-lighting has made of late years, and 
 the amount of practical chemical skill which has been ap- 
 plied to the subject, there are yet many towns in England 
 where the gas is so bad and so imperfectly purified as to be 
 quite unfit for consumption in private houses, and where 
 people are afraid to introduce it, well knowing its injurious 
 effect on many articles of value exposed to its influence. 
 
 This is an evil which must act seriously against the interest 
 of any gas company, for it prevents the proper development 
 of their business, causing continuous complaints and dissatis- 
 faction ; and when we consider the small expense incurred 
 in purifying, it becomes a matter of astonishment how it can 
 possibly be neglected. By the adoption of the following 
 tests, every manager has the means of assuring himself of 
 the purity of the gas manufactured ; and every care should 
 be adopted to make it of such a quality as to withstand such 
 tests. 
 
 Tests for Sulphuretted Hydrogen . — Test papers for detect- 
 
TESTS FOR ASCERTAINING PURITY OF GAS. 283 
 
 in g sulphuretted hydrogen are prepared by moistening 
 common writing-paper with a solution of acetate of lead or 
 nitrate of silver, the latter being the most delicate test. The 
 gas under examination is caused to impinge on the moistened 
 test-paper for about a minute, and should this become dark- 
 ened in colour, it is a proof of the presence of this impurity. 
 It may also be detected by passing the gas through solutions 
 of either of these. Another method, sometimes practised, 
 is to pass the gas into pure distilled water, then to add 
 a single drop either of the acetate of lead, the nitrate of 
 silver, or the chloride of bismuth : if any sulphuretted hy- 
 drogen be present, it will immediately show itself by black- 
 ening the water. 
 
 Test for Ammonia . — This being an alkali, the test papers 
 to be used must be either yellow turmeric paper, or litmus 
 paper first reddened by solution of vinegar or any other weak 
 acid. If the original blue colour of the litmus paper be re- 
 stored by the gas, or the yellow colour of the turmeric be 
 turned to brown, it indicates the presence of ammonia. 
 
 Test for Carbonic Acid Gas . — Paper steeped in the blue 
 tincture of litmus is rendered red both by carbonic acid gas 
 and by sulphuretted hydrogen. In order to distinguish 
 accurately which of these impurities is present, a solution 
 may be maGe of pure barytes in the tincture of litmus. If 
 the gas be passed into this solution and only sulphuretted 
 hydrogen be present, no change will be produced, but should 
 carbonic acid gas be present, a precipitate of the carbonate 
 of barytes will immediately fall down. Carbonic acid may 
 also be detected by causing the gas to blow or bubble through 
 lime-water, and if this become cloudy or milky, the presence 
 of this impurity is established. 
 
 Test papers of turmeric, litmus, or acetate of lead, are to 
 be purchased at many operative chemists in the form of 
 small books, about 3 inches long and § inch wide, each book 
 containing about 24 leaves. They are exceedingly conve- 
 nient, and no works should be without them. 
 
 A very useful little instrument is made by Mr. Wright, 
 for the purpose of detecting sulphuret of carbon in gas. 
 The presence of this compound of sulphur had long been 
 
284 TESTS FOR ASCERTAINING PURITY OF GAS. 
 
 suspected, and, as it cannot be detected by the ordinary test 
 papers which are used, has often escaped observation. Every 
 combination of sulphuric acid, however, being highly inju- 
 rious in coal gas, it is important that every possible pains 
 should be taken to remove this impurity. This apparatus is 
 equally useful for detecting sulphuretted hydrogen or any 
 other compound of sulphuric acid. 
 
 The arrangement consists of a simple apparatus for con- 
 densing the products of combustion from an ordinary gas 
 
 flame, and of applying to the liquid so condensed a salt of 
 barytes, which immediately precipitates the sulphur, when 
 present in ever so small a quantity. 
 
 In fig. 68, a is a small jet flame over which is a chimney, 
 gradually contracted into a small tube, b b, half an inch in 
 diameter, which tube is bent and carried through a metal 
 cylinder c, about 18 inches long and 2 inches diameter. 
 This cylinder is kept full of cold water, which is retained 
 
TESTS FOR ASCERTAINING PURITY OF GAS. 285 
 
 by means of screwed caps, g g , at each end, being pro- 
 vided with small India-rubber washers, which make a 
 perfect joint at each end of the tube, d is a funnel for 
 filling the tube with water, and / is a siphon by which it 
 overflows when the tube is full. The vapours which escape 
 from the combustion of the gas at a pass through the tube 
 b , in which they are condensed, and drop in the state of fluid 
 into a glass placed to receive them, while the carbonic acid 
 escapes at the same open end of the tube. The water 
 which drops from the tube is generally colourless, nearly 
 tasteless, but with a peculiar and not unpleasant odour. 
 
 When a drop of the nitrate of baryta is added to the 
 water thus condensed from the combustion of ordinary gas, 
 a flocculent white powder immediately discolours the water, 
 being the sulphate of baryta. This is considered by com- 
 petent authorities the very severest test to which gas can be 
 subjected. 
 
 To obtain the whole of the sulphur present some ammonia 
 should be placed around the jets of gas, in a vessel for the 
 purpose. The vapour of ammonia will pass up the tube, 
 and combining with the sulphurous acid, the whole of the 
 sulphur compound will be condensed in the water in the form 
 of sulphate of ammonia. 
 
 Dr. Letheby employs a similar method, but has introduced 
 an air condenser ; this is a glass vessel capable of holding 
 about one gallon ; into this the products of combustion are 
 conveyed, and there condensed, to be afterwards analysed. 
 The difference between the two apparatus being, that in 
 the former the condensation is caused by contact with water ; 
 in the latter, by radiation or contact with the atmosphere. 
 
286 
 
 ON THE MODE OF BURNING GAS. 
 
 CHAPTER XX. 
 
 ON THE MODE OF BURNING GAS. — EFFECTS OF PRESSURE, ETC. 
 
 ADMIXTURE OF AIR ON GAS. — LIGHT OBTAINED. 
 
 CARBURISATION OF GAS. 
 
 When coal gas is ignited as it issues from a burner or 
 orifice, its hydrogen is consumed at the lower part, produc- 
 ing the blue flame characteristic of it, and the carbon being 
 sufficiently heated is liberated in a solid state at the upper 
 part of the flame, if properly consumed, where it combines 
 with the oxygen of the atmosphere, again therewith resum- 
 ing the state of gas as carbonic acid : and according to the 
 degree of heat attained by the innumerable particles of carbon, 
 so will be the amount of light emitted by the gas. 
 
 Whenever the flame of gas is unduly cooled, or when 
 the gas is intermixed with a portion of atmospheric air, or 
 when it issues from the burners under great pressure, the 
 light obtained from a given quantity is very materially re- 
 duced, and when either of these contingencies is carried to 
 an extreme, no material light is obtained from gas. 
 
 To illustrate the first affirmation, I have only to call the 
 reader’s attention to a large flame issuing from a stand pipe, 
 frequently seen in London and other places where public 
 works are being carried on at night. In this a volume of 
 gas issues, giving at one moment, when the weather is calm, 
 the light of thirty or forty candles ; but at the next instant, 
 when a strong gust of wind blows upon it, a small blue flame 
 only is perceptible, the gas giving no appreciable light. It 
 may be supposed that the supply of gas is interrupted by the 
 wind, and the loss of light due to this cause. This, however, 
 is not the case, for experiment will prove it to be about 
 uniform alike in the calm and under the influence of the 
 wind ; therefore, when a flame is extremely cooled, gas gives 
 no available light. 
 
 The second affirmation, that when gas is intermixed with 
 atmospheric air the light is diminished, is witnessed daily 
 in igniting gas, when often an intense blue flame issues, 
 but giving no light : this being occasioned by the admixture 
 
oN THE MODE OF BURNING GAS, 
 
 287 
 
 of air therewith. According to Dr. Letheby, the following 
 are the proportions of light given by different quantities of 
 air being intermixed with gas, supposing the light from gas 
 unmixed with air to be 100 : — 
 
 2 per cent, of air in gas . 
 
 Light, 
 
 . . . 90 
 
 5 » )> 
 
 ... 70 
 
 7 a a 
 
 . . . 52 
 
 10 
 
 ... 34 
 
 20 ,, ,, 
 
 ... 12 
 
 40 
 
 ... 1 
 
 50 „ „ 
 
 ... 0 
 
 These results do not correspond entirely with the experi- 
 ments of Messrs. Audouin and B6rard, already referred to, 
 which may arise from the especial manner the gas was 
 consumed, or perhaps from its quality. However, the per- 
 nicious effect of an admixture of air with gas is fully 
 demonstrated, and requires the utmost attention to avoid it 
 either in the production, transmission, or consumption of 
 gas. 
 
 The affirmation, that the light given from gas is influenced 
 according to the pressure with which it is emitted from the 
 burners, requires to be illustrated by experiment ; and for the 
 purpose let us take an argand burner, having fifteen holes of 
 such dimensions as to permit 5 feet per hour to issue with a 
 pressure of about *roth inch, when with ordinary gas from 
 Newcastle coal we would obtain a light equal to about twelve 
 candles. Now, if we reserve the same form and size of 
 burner in every respect, but diminish the size of the holes so 
 that a pressure of i^rths is necessary to expel the 5 feet of gas 
 per hour, then the light will only be equal to five and a 
 half candles ; and if we further diminish the size of the holes, 
 so that Toths pressure will be required to expel the 5 feet, then 
 that quantity of gas produces a blue flame, but no material 
 light. With a fishtail burner, consuming at a low pressure 
 4 feet per hour, the light of seven candles may be given , 
 but by increasing the pressure to expel 8 feet per hour 
 from the same burner, the light is then diminished, and 
 with 15 feet per hour there is very little light. All 
 descriptions of burners are liable to this variation ; and it 
 is a most important consideration to all connected with gas 
 
288 ON THE MODE OF BURNING GAS. 
 
 lighting, but more particularly to the manufacturers of 
 burners. 
 
 There is another important consideration in the consump- 
 tion of gas, namely, its power of giving light. Gases are very 
 variable in this respect, as the following table demonstrates. 
 
 Table of Light yielded by various descriptions of Gas, when 
 
 BURNED UNDER FAVOURABLE CIRCUMSTANCES, AND AT THE RATE OF 
 5 FEET PER HOUR. 
 
 Anthracite, and some lignites, equal to from 3 to 10 
 
 Newcastle average 12 
 
 Knights wood Cannel 18 
 
 Ramsay’s „ 20 
 
 Wigan „ .20 
 
 Amiston „ 22 
 
 Lesmahago ,, 24 
 
 Boghead ,, 36 
 
 candles. 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 a 
 
 This variation in the luminosity of different kinds of gas 
 is due to the quantity of carbon they relatively contain, which 
 carbon separates at the moment of ignition from the hydrogen 
 in very minute, solid particles, and, by intermixing with the 
 oxygen of the atmosphere, assumes a state of incandescence ; 
 and, according to the number of these solid particles of carbon 
 in gas, so is the amount of light to be derived from it. But 
 it is essential for the carbon to attain the necessary degree 
 of heat to combine with its equivalent of oxygen. In 
 the event of the supply of this being deficient, the carbon 
 then passes off in the solid state, distributing itself on the 
 ceilings of apartments, the atmosphere, &c., as smoke. There- 
 fore, for the perfect combustion of gas, the proper supply of 
 atmospheric air requires the greatest attention. 
 
 There is, however, another action takes place when the 
 particles of carbon are cooled below the point necessary for 
 their incandescence. In this case the carbon does not assume 
 the solid form, but unites with the oxygen the same instant it 
 leaves the hydrogen ; thus, as Mr. Wright observed, pass- 
 ing from an union with one solvent (if the expression may 
 be used), to unite with another solvent, and is completely 
 consumed before it has been submitted to the high tempera- 
 ture essential for the separation of the carbon. 
 
 Thus for the economical consumption of gas there are 
 
ON THE MODE OF BURNING GAS. 
 
 289 
 
 various points for consideration, which, however, are resolved 
 into two simple questions; the one, to avoid an excess of atmo- 
 spheric air with the flame, the other, to ensure a sufficiency 
 of this to combine with the carbon of the gas. 
 
 Having attempted the explanation of the contingencies in 
 the combustion of gas, it now becomes a question to consider 
 the mode of obtaining the maximum of light from a given 
 quantity. 
 
 For this purpose, as a rule, the best results are obtained 
 when the gas issues from the orifices of argand burners at 
 about -roth inch pressure ; but fishtails and batswings, to burn 
 advantageously, require a pressure of i%ths or -i- 0 ths. The 
 holes of burners destined for poor gas should be large, so that 
 the minute particles of the carbon in the gas when issuing 
 become heated to the necessary extent to produce light. The 
 holes of burners destined for rich gas should be small in 
 proportion to the richness of the gas, in order that the par- 
 ticles of carbon t may unite with their equivalents of oxygen 
 from the atmosphere, and give light instead of passing off in 
 the solid state as smoke. The orifices of the interior and the 
 exterior of argand burners should be adjusted according to 
 their relative sizes and quality of gas. 
 
 Burners, whether argand, batswing, fishtail, or jet, give 
 the maximum of light only with one particular consumption ; 
 and this depends on the quality of the gas, — for example, the 
 maximum of light from 12-candle gas, with an argand, is 
 when it has 30 holes, and consuming about 7^ feet per hour. 
 The richer kinds of gas are consumed in smaller quantities. 
 
 An argand burner, with 15 holes, varies in the following 
 extraordinary manner : — 
 
 When consuming 5 feet per hour, the light is equal to 12 candles. 
 
 „ diminished to 3J „ „ „ 45 „ 
 
 9i 1 *9 
 
 a a *2 a if a A ^ a 
 
 1 i. 0*9 
 
 a a x 2 a a a u “ a 
 
 a a f a a a 0 ^2 a 
 
 The other burners follow the same law ; for instance — 
 
 A fishtail consuming 5 feet per hour, the light is equal to 10 candles. 
 The same reduced to 3J „ „ „ 5'5 „ 
 
290 
 
 ON THE MODE OF BURNING GAS. 
 
 All burners require to be made especially for the quality of 
 gas they are destined to consume ; therefore, a particular 
 standard burner, or fixed rate of consumption for all classes of 
 gas, is erroneous ; for an argand burner, which may be 
 well adapted for burning 12-candle gas at 5 feet per hour, 
 would be ill adapted for burning the same quantity of M or 
 16-candle gas, and still worse for the richer qualities. There- 
 fore, it would appear that the Act of Parliament which 
 defines the mode of testing the illuminating power of gas by 
 restricting the holes of an argand to 15, and the consumption 
 to 5 feet per hour, is prejudicial to gases of higher illuminat- 
 ing power ; for, in the event of gas, say of a quality equal to 16 
 candles, being so consumed, either a large portion of it would 
 pass off as smoke, or the holes would have to be so con- 
 tracted in size as to prevent the quantity issuing except 
 under an increase of pressure, both circumstances being 
 unfavourable to the richer gas. 
 
 As gas is generally employed either in places where the 
 standard of quality is 12 candles, or in Scotland, where it is 
 2 4c candles, the average light yielded from each burner is 
 about 12 candles. Perhaps, therefore, in estimating the value 
 of gas, the correct manner would be for the richer gases to 
 be brought to the standard of the poorer, by defining the 
 quantity necessary to give the light of say 12 candles, which 
 might be taken as a standard. According to this method, 
 and adopting the table already mentioned as correct, 
 
 5 feet of Newcastle gas 
 
 31 „ Knightswood „ 
 
 2j „ Lesmahago „ 
 
 1J „ Boghead „ 
 
 Of course the intermediate quantities could be readily defined 
 according to the required standard of gas. 
 
 It is generally believed that for poorer gases the argand 
 burner is superior to the others, and for richer gases that the 
 fishtail is the most suitable. The latter has the great dis- 
 advantage that, under excess of pressure, gas passes off imper- 
 ceptibly without giving light. Notice of this is given with 
 the argand and batswing by the smoke engendered, when 
 the evil may be corrected. 
 
 ' would be ‘equal to the standard, 
 or 12 candles. 
 
CARBURISATION OF GAS. 
 
 291 
 
 No general rule can be laid down for tlie sizes of the holes 
 of the various burners, — this must be obtained by experi- 
 ment, by regulating the holes so as to cause the required 
 quantity to issue at the low pressures already referred to. 
 The external and internal supply of air to the argand, as also 
 the length of the glass chimneys, require great care in 
 defining them. The slits of batswing burners should be 
 always at least as deep as the diameter of the nib, so to form 
 a good deep flame. The angles of the holes of fishtails 
 require particular attention in drilling ; in experimenting, the 
 results of these are very variable. 
 
 CARBURISATION OF GAS. 
 
 There is a method of enriching gas by causing it to pass, 
 just previously to its combustion, through the vapours of car- 
 bonaceous liquids, as naphtha 7 , spirit of petroleum, &c., whereby 
 additional particles of carbon are communicated to it, and 
 held mechanically in suspension for a brief period until 
 ignited. This process is called carburisation. 
 
 This system was first patented by Mr. Lowe in 1831, 
 when he proposed to produce carbonic oxide, and enrich it 
 with “ the vapour of essential oil (liquid hydrocarbons) or 
 other illuminating material,” and the following year the same 
 gentleman patented the means of “ increasing the illuminating 
 powers of coal gas, by impregnating it with the vapours of 
 naphtha, commonly called spirit of coal tar, or with any other 
 hydrocarbonaceous liquid, by any convenient method.” 
 
 Since that period various patents have been obtained from 
 time to time for analogous processes — these being for com- 
 bining the volatile hydrocarbons with atmospheric air, 
 hydrogen, and other gases ; but the only manner of applying 
 the system economically is, as proposed by Mr. Lowe, by 
 intermixing these vapours with gas. Some years ago this 
 was tried on an extensive scale, under the directions of the 
 patentee ; and although gas was at that period twice its 
 present price, it did not succeed. 
 
 Within the last three or four years the same principle has 
 been revived with all pretensions to originality, and it must 
 be admitted that great efforts have been made to render it 
 
 o 2 
 
292 
 
 CARBURISATION OF GAS. 
 
 successful ; for the hydrocarbon liquid is prepared expressly 
 for the purpose, the apparatus employed are probably much 
 superior to those formerly in use for the object, and there is, 
 moreover, greater confidence in the issue ; but there still 
 remains a strong doubt as to its ultimate success. 
 
 The main difficulty existing against the carburisation of gas 
 is the irregular evaporation of the liquid ; a portion of which, 
 when first placed in the carburating vessel, is remarkably 
 volatile, and passes off in abundance, requiring burners with 
 small holes to prevent the formation of smoke. By degrees, 
 when the most volatile vapours have evaporated, the gas in 
 consequence not being enriched, a difficulty arises from the 
 smallness of the burners, which, as already explained, give, 
 for the quantity of gas consumed, a very diminished light. 
 
 I subjoin an account of two experiments made in order to 
 ascertain the rate of evaporation of liquid hydrocarbon. 
 The material chosen was the spirit of petroleum, as light as 
 it could be procured, being about 700 specific gravity. A 
 portion was placed so as to fill a test-tube 4 inches long and 
 half an inch wide, having a scale of the same length- attached 
 to it, and divided into fractional parts of inches, for the pur- 
 pose of appreciating the amount of evaporation. The first 
 hour the evaporation was |th of an inch, or -^nd part of the 
 whole; the second hour it was about y^th of andnch; and 
 at the end of twenty -four hours was fths of an inch. The 
 second day the evaporation was less than an inch, and at 
 ihe end of fourteen days it amounted to inches, and in a 
 month had increased to nearly 3 inches. Continuing the 
 experiment, at the end of four months, there still remained 
 J an inch, or ^-th of the whole of the liquid, which was highly 
 carbonaceous, but not volatile. The temperature of the 
 apartment in the meantime had varied from 45° to 75° Fahr. 
 
 The other experiment was with 3 lbs. of the same material 
 placed in a suitable vessel in such a manner as to expose a 
 large surface for evaporation ; and on passing atmospheric 
 air therethrough by means of a motive-power meter, a very 
 large and rich flame, giving off abundance of smoke, was the 
 result. This at the commencement, when adjusted to 5 feet 
 per hour, gave a light equal to sixteen candles, but speedily 
 
CARBURISATION OF GAS. 
 
 293 
 
 the flame became perceptibly less ; in a short time it was 
 diminished to a remarkable extent ; after twenty -six hours 
 merely a bine light was obtained, and at the end of forty- 
 eight hours no flame whatever existed, as all the volatile 
 constituents at the temperature of the atmosphere had evapo- 
 rated ; on reweighing the residue, barely one-half of the total 
 quantity had been available. This clearly demonstrated how 
 easily people may be deceived by a carefully prepared experi- 
 ment ; for, at the commencement, the air was so highly charged 
 with carbon as to occasion the greatest surprise, but as this was 
 of such short duration, on account of the very small quantity 
 of the highly volatile material, the experiment was very de- 
 ceptive, and the process of carbonising the air utterly useless. 
 
 These experiments are highly instructive as regards the 
 carburisation of gas ; they show the great irregularity in the 
 evaporation, also that a portjon of the liquid will not evapo- 
 rate with sufficient rapidity under ordinary temperatures, 
 and they show that a portion does not evaporate. If, on the 
 contrary, the liquid evaporated regularly, even although 
 it might require a comparatively high temperature for the 
 purpose, then the carburisation of gas would be a very 
 valuable adjunct to gas-lighting, as it would give to ordinary 
 gas all the advantages of cannel, producing less heat for a 
 given quantity of light, securing better ventilation, and the 
 agreeable glow produced by the light of rich gas, which is 
 an advantage much to be desired. 
 
 There are, however, several firms established in London 
 and elsewhere for carburating gas; they supply the appa- 
 ratus and liquid; they undertake the exchange of the non- 
 volatile for the volatile liquid ; and, indeed, attend to the 
 entire process, taking all trouble and responsibility from the 
 gas consumer who adopts the system. 
 
 The process of carburisation was tried for one or two 
 years on the public lamps in the City of London ; and, 
 according to the estimates of the projectors, a considerable 
 economy was to be effected, together with a great increase 
 of light. To obtain these advantages, it was necessary to 
 change the ordinary burners, consuming o feet per hour, and 
 replace them by others consuming only 3 feet, which ol 
 
294 
 
 RESIDUAL PRODUCTS FROM 
 
 course diminished very materially the account of the gas 
 company ; but, as the sequel will clearly prove, was not an 
 economy. The carburising apparatus being placed in the 
 lanthorns, were unsightly, besides throwing great shadows. 
 The gas at one period, when supplied with fresh naphtha, 
 issued with a smoky flame, rendering in a single night the 
 glasses dirty and obscure ; but in the course of a short time 
 the naphtha was useless, when, on account of the very small 
 burners, the gas was consumed under a great disadvantage, and 
 the light given was diminished to a serious extent. After a 
 long trial it was renounced, on account of the difficulties it 
 possessed and the absence of the economy anticipated. 
 
 CHAPTER XXI. 
 
 THE RESIDUAL PRODUCTS FROM THE DISTILLATION OF COAL,. 
 
 COKE. 
 
 The most important commercial commodity of these is the 
 coke, which is an excellent fuel for household purposes, and 
 much used in the arts and manufactures. The breeze or 
 small of this is generally sold for the purpose of brick- 
 making, but where fuel is dear it is often intermixed with a 
 small portion of tar, and subjected to great pressure in suitable 
 moulds, and so formed into blocks or bricks. These are after- 
 wards placed in ovens and submitted to a moderate degree 
 of temperature, in order to expel the volatile matter, as water 
 and naphtha, when a very good artificial coal is produced. 
 
 The coke obtained from caking coal is much superior to 
 that from canned coal ; although the latter is very compact in 
 its nature, it is very small, and comparatively possesses little 
 value. The coke from cannel coal is sometimes reduced to 
 powder, and intermixed with tar, compressed, and evaporated, 
 and makes a very good substitute for charcoal, and is called 
 by the French u charbon de Paris ,” Paris charcoal. The 
 coke from Boghead cannel is useless as fuel, but is sometimes 
 employed as a deodorising agent. 
 
DISTILLATION OF COAL. 
 
 295 
 
 TAR. 
 
 Although not the most valuable, this is the most interesting 
 of the residual products from coal. As already demonstrated, 
 when the retorts are at a low heat this is produced in abun- 
 dance, and probably with very careful manipulation coal 
 could be carbonised without any material quantity of tar 
 being produced. 
 
 Among the first attempts to profit by this residue, was one 
 to distil and convert it into gas, and the experiments connected 
 therewith were sufficiently satisfactory to induce a large ex- 
 penditure to carry it into practical operation ; but this, when- 
 ever attempted, has always terminated in failure. The diffi- 
 culties attending the operation are various : the tar cannot 
 practically be decomposed with the required regularity ; it 
 speedily obstructs the ascension pipes from the retorts with a 
 solid mass of pitch ; the gas when produced from it has a 
 great tendency to form itself into naphthaline, which stops 
 the mains ; and it is also believed that it does not chemically 
 combine with gas produced in the ordinary manner, and in 
 consequence is deposed in its passage through the pipes. 
 With these difficulties, the distillation of tar for the produc- 
 tion of gas has for some years been abandoned. 
 
 The products from coal tar are very numerous ; by careful 
 distillation it yields naphtha suitable for burning in lamps, 
 or for dissolving India-rubber, making varnish, &c. ; benzole 
 is also obtained from it ; this is useful for extracting oils and 
 grease from woollens, and a later residue of the distillation 
 of tar is the dead or heavy oil much used for preserving 
 railway sleepers and other timber exposed to the action of 
 the soil and atmosphere. Amongst the other volatile results 
 is paraffin oil, used very extensively in lamps, also an excel- 
 lent oil for lubricating machinery. Paraffin tor candles, ex- 
 celling for whiteness and beauty the best wax, is also extracted 
 from tar. The various dyes known as magenta, aniline, and 
 rosoline, are all obtained from gas tar, and according to the 
 opinion of many chemists much of the worth of this important 
 material remains to be discovered. 
 
 The volatile parts of tar being expelled, pitch, used as a 
 
296 RESIDUAL PRODUCTS FROM DISTILLATION OF COAL. 
 
 substitute for asphalte, is obtained, which is employed for 
 paving, or rendering walls or floorings impermeable to mois- 
 ture. The pitch upon being distilled in suitable retorts gives 
 off the best dead oil for preserving timber, and a very excellent 
 coke for foundry purposes is produced, this being exceedingly 
 compact and hard, and does not possess the least sulphur, the 
 presence of which is always injurious to iron when smelted. 
 
 AMMONIA. 
 
 This is also an important residue in the distillation of coal. 
 It is sometimes obtained in the manner already described in 
 Mr. CrolFs process, at other times taken direct from the con- 
 denser to be manufactured ; but more generally the liquid 
 of condensation is concentrated by being pumped repeatedly 
 over and over again into the scrubbers, where it absorbs the 
 ammonia from the gas, and when sufficiently saturated is 
 withdrawn and manufactured, so by this means serves as a 
 purifying agent, and at the same time becomes more valuable. 
 
 The simplest mode of manufacturing the ammoniacal 
 liquor is to put slacked lime into a boiler, which is after- 
 wards charged with the liquor, and when heat is applied the 
 vapours of ammonia are caused to pass over into a vessel 
 containing sulphuric acid, and this when neutralised is eva- 
 porated and produces sulphate of ammonia, of which there 
 is a very large demand for agricultural and other purposes. 
 This process is adopted by many works at the present time. 
 
 Volatile alkalies, the carbonate of ammonia, muriate of 
 ammonia, or sal-ammoniac, as well as all the other compounds, 
 are produced from the gas-works’ residues. Trials have been 
 made to prepare Prussian blue and madder dye therefrom ; 
 the first has been carried into operation, but does not produce 
 the same brilliancy of colour as that ordinarily found in com- 
 merce. 
 
 WASTE LTME FROM PURIFIERS. 
 
 The residue obtained from the wet lime purifiers has such 
 a disagreeable odour that even its transport through the 
 streets is the source of serious annoyance. It has been pro- 
 posed to extract the sulphur from this, as well as the dry 
 
EXPLOSIONS OF GAS. 
 
 297 
 
 lime, by roasting it in ovens; but all who have adopted it 
 agree that the system is not profitable. The wet lime residue 
 is disposed of generally by mixing it with loam for luting the 
 retort doors, for which purpose it is suitable. 
 
 The dry lime sometimes finds a ready sale, being in some 
 descriptions of ground very valuable as a fertilising agent. 
 The residue from the oxide of iron purification is generally 
 repurchased by the firms supplying the material, who, it is 
 stated, derive considerable advantage from it. 
 
 CHAPTER XXII. 
 
 EXPLOSIONS OF GAS. 
 
 When lighting by means of gas was first proposed, the fears 
 of explosions were the strongest arguments against its adop- 
 tion, and several scientific men of the period attempted to 
 reduce these casualties to a positive law, by asserting that 
 a gasholder containing 15,000 feet of gas would in exploding 
 be as destructive as ten barrels of gunpowder. As a further 
 proof of the slight knowledge of the nature of gas at the time, 
 Sir William Congreve, with other learned gentlemen, when 
 acting as a royal commission of inquiry on the subject of gas 
 explosions, recommended that gasholders should be exceed- 
 ingly limited in their dimensions (not to surpass 6,000 cubic 
 feet each), and, further, that they should be surrounded by 
 strong walls, to confine the disastrous effects of explosion 
 should it occur. 
 
 We can look with satisfaction to the advancement science 
 has made in connection with this subject, for now we know, 
 instead of gas being so terribly destructive, that when un- 
 mixed with atmospheric air or oxygen, it is as harmless as 
 regards explosion as the water in the tank beneath it ; and 
 if it were possible to insert a lighted torch, or taper, into a 
 holder containing gas, instead of the gas exploding, the flame 
 would be extinguished. In other words, gas unmixed with 
 oxygen suffocates flame, and in this state cannot ignite or 
 explode. 
 
 o 3 
 
298 
 
 EXPLOSIONS OF GAS. 
 
 That explosions by gas have occurred, and do sometimes 
 even now happen, is well known, but these have been, and 
 are, so remarkably few in number, that the extraordinary 
 safety of gas lighting is as fully established as the safety of 
 railway travelling under the most careful supervision ; how- 
 ever, by treating on these accidents, and describing their 
 causes, is to adopt the proper step to prevent them. 
 
 Explosion is an instantaneous ignition of a mass, and that 
 mass may be solid or gaseous ; thus, a mixture of charcoal, 
 sulphur, and nitre in certain proportions, and prepared in a 
 particular manner, form gunpowder, which ignites instanta- 
 neously, and the increased volume, occasioned by the solid 
 assuming the gaseous state, is the cause of the force or power 
 attending the combustion. There are numerous other solid 
 compounds even more explosive than gunpowder, but the 
 simple mention of this will be sufficient as example. 
 
 Certain gases, like the solids, when intermixed in due 
 proportion, are likewise capable of instantaneous combustion ; 
 for instance, hydrogen when intermixed with oxygen, as 
 before stated, in the proportion, by volume, of two of the 
 former and one of the latter, ignites, producing explosion ; 
 and coal gas when combined with air in certain proportions 
 is also explosive, this being due to the hydrogen and carbon 
 composing it entering into combination with the oxygen of 
 the atmosphere, producing water and carbonic acid gas ; and 
 the nearer they approach to the proper proportions for the 
 perfect formation of these compounds, the greater is the force 
 of explosion. A mixture of seven parts of air and one of gas 
 is considered to be the most explosive compound, but this 
 must depend on the quality of the gas. Mixtures of less 
 than three of air to one of gas, or more than eleven of air and 
 one of gas, do not explode. 
 
 Explosions from gas are exceedingly rare. By a Divine 
 ordinance, the odour arising from gas is generally so repul- 
 sive as to awaken in the minds of the most callous a desire 
 to avoid the inconvenience, and in so doing the danger is 
 averted. However, there are circumstances where this 
 notice by odour is not manifested, as where from the light- 
 ness of the compound it ascends in the atmosphere above ; 
 
EXPLOSIONS OF GAS. 
 
 299 
 
 but when in dwellings or other buildings the slightest odour 
 of gas is noticed, it should always be attended to. 
 
 At one period or other, in some of the largest cities of 
 the United Kingdom, as well as those of the Continent, gas- 
 works have been the scenes of explosions. This has often 
 arisen from a new gasholder, when nearly terminated and 
 ready for use, having, from a very simple oversight, been 
 communicated with the manufacturing apparatus; and it has 
 afterwards happened that through a leaky valve allowing the 
 gas to pass, or perhaps by some careless person thoughtlessly 
 opening the valve, the gas has entered, intermixed with the 
 air in the holder, and the accidental production of a light has 
 caused the disaster. Therefore, when new holders are con- 
 structed they should either not be communicated, with the 
 manufacturing apparatus until quite terminated, or the pipes 
 should be “ logged,” or sealed with water, so that no gas can 
 possibly enter until quite ready for use. 
 
 But explosions of this nature have occurred when the 
 holder was being first filled with gas ; one of the most 
 remarkable took place a few years ago, by which the engineer 
 was killed. This arose from a defect in the construction, and 
 want of ordinary caution on the part of the unfortunate suf- 
 ferer. The facts are simple, for the holder on being charged 
 with gas at the commencement of the operations contained a 
 considerable quantity of air, the two forming an explosive 
 compound, and by a singular fatality it happened that the 
 holder was so far bound, or set, as not to give any pressure. 
 The engineer, desirous of judging the quality of gas, very 
 imprudently tried it at an open orifice of about £ inch dia- 
 meter; the consequence was, the flame entering, the explo- 
 sive compound in the holder ignited, and produced the 
 disaster. Had the gas been tried by an argand or fishtail 
 burner the accident would not have occurred, the holes in 
 these being too small to permit the flame to enter. 
 
 Explosions have taken place in station meters when newly 
 erected, just previously to their use, this arising from causes 
 already mentioned — by leaky valve, or by unnecessary 
 meddling on the part of the workpeople. On one occasion 
 which came under the writer’s notice, a calamity of this kind 
 
300 
 
 EXPLOSIONS OF GAS. 
 
 occurred from the mixture taking fire through the meu 
 making the joint with overheated lead. And this suggests 
 the varied opinions as to the possibility of a spark igniting 
 gas. The general opinion is that gas cannot be ignited by that 
 means ; and, indeed, it is difficult to be done, but by chance 
 a spark may be produced of sufficient heat to inflame gas. 
 
 Accidents have frequently occurred when laying mains ; 
 often occasioned by a bladder-valve, which has permitted a 
 small portion of gas to pass into the main beyond it, where 
 the explosive compound was formed, and by the merest 
 hazard a neighbouring light has produced the calamity ; 
 therefore, in laying mains, when practicable it is always 
 better to have a sheet-iron temporary valve, which is done 
 by having the spigots of two pipes together where the 
 stoppage is desired, and a thin sheet of iron between them, 
 which may be clayed or cemented round to prevent the leak- 
 age of gas. The plate can be removed when requisite, and 
 a temporary or permanent joint made with a running socket. 
 
 An erroneous impression exists that if a gasholder were to 
 be rent by accident, and the gas ignited, whenever the holder 
 touched the ground, and there being no pressure, that the 
 contents would explode. This is incorrect, for, no matter the 
 size of the opening, when the pressure ceased the gas would 
 be extinguished ; but from this moment danger would com- 
 mence, for a portion of the gas remaining in the crown 
 would gradually issue, and air take its place, so by degrees 
 an explosive compound would be formed. 
 
 An explosive compound of gas when under pressure only 
 ignites at the exterior of the pipe ; but if the pressure be 
 taken off, the flame enters, and it explodes. 
 
 In illustration of these assertions, I will relate a few expe- 
 riments entered into by myself in order to be convinced of 
 some of the circumstances under which explosions take place. 
 The most suitable and available vessels for the purpose were 
 old tin-plate meter cases of the larger sizes. These were entirely 
 closed except at the outlet and the bottom, or emptying plug. 
 In the first, a 50-light, the gas was allowed to flow through for 
 a considerable time, when the bottom plug was replaced and 
 a light applied to the outlet. The gas then burned with a 
 
EXPLOSIONS OE GAS. 
 
 301 
 
 flame the diameter of the pipe, and about 18 inches high, 
 but this quickly diminished until it died out or was extin- 
 guished. This was tried several times with the same result, 
 thus proving that when gas is enclosed in a vessel, the moment 
 the pressure ceases the flame is extinguished. But by allow- 
 ing the vessel to remain some time, and afterwards applying 
 a light, it was shattered to pieces ; which arose from a part 
 of the gas having gradually escaped, in the meantime air 
 entering and combining with the remainder, so forming an 
 explosive compound. 
 
 Another similar vessel was again charged as before, but 
 in this instance the bottom plug was left open, and on apply- 
 ing the light the flame was considerably higher and more 
 vivid than in the former experiments, caused by the gas 
 ascending by its lightness, air entering by the lower orifice 
 to fill the place of the gap ascending. Gradually the flame 
 became dimmer and dimmer, and at last changed to a deep 
 blue, when it suddenly entered like an inverted cone, and 
 explosion took place, shattering the meter case, and throwing 
 its ends a distance of several yards. 
 
 On another occasion, on making a trial with a very small 
 holder containing 2 feet of explosive compound, with a pres- 
 sure of T^ths, the gas issuing from a £-inch orifice, it ignited 
 with a very intense blue flame ; but on taking the pressure 
 off the holder and applying the light, explosion occurred, 
 lifting the holder from its place, and throwing the water of 
 the tank in every direction. 
 
 I need hardly say that these experiments require great 
 care. Thin tinned iron vessels are sufficiently strong ; and 
 as the debris is thrown a considerable distance, too much 
 caution cannot be exercised. When a cylindrical vessel is 
 subjected to explosion the ends generally give way, whilst 
 the sides remain intact. 
 
 The explosion of gas w’as formerly considered to be due to 
 the hydrogen in combination therewith, which assertion was 
 maintained by Sir William Congreve. However, it is now 
 established that the richest gases are the most destructive 
 when exploding. 
 
 An explosive mixture always possesses a very powerful 
 
302 
 
 EXPLOSIONS OF GAS. 
 
 odour of gas ; this is sufficient to indicate to any one that a 
 light should not be approached ; and under these circum- 
 stances, when in dwellings, ordinary precautions only are 
 requisite ; above all to have no lights near, and to open the 
 doors and windows, the upper part of the latter especially, as 
 gas by its lightness ascends, and will readily escape thence. 
 The main tap should be turned off, and a careful inspection 
 made, when perhaps a burner will be found turned on, or an 
 hydraulic joint without water, or some other defect which can 
 easily be remedied. No one should ever apply a light where 
 there is an odour of gas in the upper part of an apartment ; 
 many little mishaps have occurred through neglecting this 
 precaution. Should there be any escape which can only be 
 detected by flame, the gas ought to be turned off for two or 
 three hours, and the other precautions being adopted, the 
 light may be applied the moment the main tap is turned 
 on; but it is always better and safer to detect escapes in 
 dwellings without the employment of a flame, it requiring 
 only a little more patience. 
 
 Meters are sometimes mysteriously destroyed by explosion, 
 even when fixed in their places. The syphon plug when not 
 sealed by water, and the tap of a burner being left open, are 
 sufficient to permit air to enter and form the explosive com- 
 pound, and a light being applied to an orifice without a burner, 
 the flame enters, but does no injury beyond rendering the 
 meter useless. 
 
 Of the few explosions that have occurred in gas-works, the 
 majority have arisen from having the pipes in vaults and 
 tunnels, or perhaps from open spaces existing under some of 
 the apparatus, generally with the view of seeing to the per- 
 fect condition of the pipes, &c. From this originated the 
 first two accidents of the kind, which befell Mr. Clegg, form- 
 ing a very powerful argument against the use of subways, pro- 
 posed some time ago, for containing gas mains; and if 
 these were unfortunately to be carried into operation, all the 
 extravagant fears of danger which existed at the introduc- 
 tion of gas would certainly be realised. 
 
 It is well known that mains as now placed, even in isolated 
 places where there is little traffic, are sometimes unaccount- 
 
EXPLOSIONS OF GAS. 
 
 303 
 
 ably broken, and this when entirely protected from the effects 
 of severe cold or frost by the depth they are laid. It is 
 also well known that cast iron, and even wrought iron, have 
 a tendency to. become brittle when exposed to the action of 
 frosty weather ; therefore we may reasonably suppose that, if 
 mains break as now placed, accidents of this nature would 
 be considerably more frequent if they were placed in these 
 subways and subjected to the action of frost. 
 
 In the event of a pipe breaking as mains are at present laid, 
 the gas may percolate through the earth and be lighted on 
 the surface, or even a portion may find its way into the 
 sewer, in both cases giving timely notice for reparation ; but 
 if such an event occurred with a pipe when enclosed in the 
 subway it is difficult to imagine the consequences ; an ex- 
 plosion under these circumstances would cause houses to 
 totter to their foundations — probably shatter the subway con- 
 taining them ; and in the midst of all this, the only possible 
 means of remedying the evil would be to shut the valves 
 which communicate with the broken pipe, and so put the 
 district in total darkness, thus increasing the terror of the 
 inhabitants, and offering facilities for committing depredation 
 with impunity. 
 
 There are minor objections against the use of subways, such 
 as their excessive cost, and the difficulty of attaching services, 
 which could only be done with safety by shutting off the 
 supply in the neighbourhood, and this, to use the mildest term, 
 would be a very serious inconvenience. These and many 
 other reasons are sufficient to prevent subways for gas ever 
 being successfully employed ; they may be tried, and may be 
 used under certain circumstances, but can never be carried 
 into operation successfully in the streets of a city. 
 
 On the occasion of a fire occurring near a gas-works, the 
 public journals generally fall into error by assuming the con- 
 tents of the gasholders to be explosive, and conjecture the 
 amount of damage that would arise from this event occurring, 
 the excitement being much increased by this mis-statement. 
 Gasholders when in use, that is, containing ordinary gas, 
 cannot by any means explode, even although the plates 
 forming them were to be made red-hot by the flames : all that 
 
304 
 
 ON WATER GAS. 
 
 could occur is that the gas, expanded by the heat, would issue 
 in detached flames, but no explosion could take place. Another 
 common error, when an edifice, as a theatre, takes fire, is 
 to turn off the gas to prevent explosion, and this is done 
 sometimes at the risk of putting the audience in darkness to 
 find their way out in the best manner they can. Nothing is 
 more absurd ; for supposing, at the worst, the fire to melt 
 the pipes in the building, and the gas to issue, the same flame 
 which melted the pipe would ignite the gas, so that explo- 
 sion is not possible under these conditions. A good system 
 is to have a valve or valves on the exterior of all public 
 buildings of resort, which, in the event of a fire unfortunately 
 occurring, can be shut off after all the people have left the 
 building, so preventing the destructive effects of the flame 
 should the gas ignite, and the loss of gas. 
 
 CHAPTER XXIII. 
 
 ON WATER GAS, OR THE HYDROCARBON PROCESS OF GAS- 
 MAKING. 
 
 If, as already stated, the steam or vapour of water be passed 
 through a red-hot iron tube, it is decomposed, and hydrogen 
 gas given off in considerable quantities : 10 lbs. or 1 gallon 
 of water will yield 210 cubic feet of hydrogen gas, which, 
 although possessed of considerable heating power, is quite 
 worthless for illuminating purposes. 
 
 Hydrogen gas, however, has been successfully applied for 
 heating stoves, and when the jets of this are made to burn 
 in a stove filled up with loose fragments of platinum -foil, a 
 very cheerful-looking fire is produced, well known to the 
 public from its frequent exhibition at the Polytechnic Insti- 
 tution of London by Professor Bachhoffner, under the name 
 of Bachhoffner’s polytechnic fire. 
 
 No systematic manufacture of hydrogen gas has been 
 attempted on the large scale for the purpose of heating, 
 although it has been proposed on various occasions. Several 
 patents have been taken out for producing hydrogen gas 
 
ON WATER GAS. 
 
 305 
 
 from water, and bringing it into combination with the 
 rich gases derived from oil, resin, tar, naphtha, cannel coal, 
 and other materials which yield highly illuminating gases. 
 Among those who have obtained patents of this kind are 
 Messrs. Donovan, Lowe, Manby,Val Marino, Hadley, White, 
 Oroll, Webster, Barlow, and Gore. 
 
 Although the processes indicated by all these patents 
 differ very slightly from each other, if indeed they are not 
 in some cases perfectly identical, the only one which was 
 carried out in a really practical manner was that of Mr. 
 Stephen White. Under the patents of this gentleman the 
 towns of Ruthin, Southport, Warminster, Dunkeld, together 
 with many mills and factories in Lancashire, were lighted 
 with hydrogen produced from water and combined with the 
 gas from resin or cannel coal, and called the hydrocarbon 
 process. 
 
 About twelve years ago, when this treatise was first pre- 
 sented to the public, the hydrocarbon process was in great 
 favour, and very sanguine expectations existed of its success. 
 Amongst its ablest supporters were Dr. Frankland and the late 
 Samuel Clegg, both of whom were entitled to the utmost 
 confidence — the former on account of his profound chemical 
 knowledge and the general accuracy of his opinions — the 
 latter for his great ability and having been so intimately and 
 honourably associated with gas-lighting from its earliest date. 
 
 At the period mentioned, some sanguine minds gave the 
 most extraordinary accounts of the process in question. Mr. 
 Clegg’s statement of the process was undoubtedly of a very 
 extravagant nature, for he assigned 75,000 feet of 12-candle 
 gas as the produce of one ton of Boghead coal when so 
 treated, and it is inconceivable how he could have fallen into 
 this error, inasmuch as this production is literally impossible, 
 for the weight of that quantity and quality of gas would be 
 about 1 ton 1 cwt., whereas the whole of the volatile portion 
 of a ton of Boghead coal, together with the weight of the 
 hydrogen intermixed with it to form 75,000 feet of gas, 
 would be under 15 cwt. ; therefore if the quantity stated 
 were obtained, it could not be of the quality indicated. 
 
 However, the process was so well supported as to induce 
 
306 
 
 ON WATER GAS. 
 
 many companies to make trials on an extensive scale; 
 amongst these were the Manchester and South Metropolitan, 
 and during several months, the engineers of these establish- 
 ments did their utmost to ensure success; but experience and 
 time proved the fallacy of the system, and the results of 
 these extensive experiments only made evident the imprac- 
 ticability of the hydrocarbon process. Whilst the towns 
 before mentioned which were supplied by these means, 
 instead of yielding profit, as was afterwards the case when 
 coal gas was adopted, suffered one continuous loss. 
 
 The causes of this signal failure were various. Firstly : 
 The production of hydrogen by the decomposition of water 
 is very costly ; under the most favourable circumstances 
 much more fuel being required to produce a given quantity 
 of gas from water than from coal. Secondly : Hydrogen 
 when so produced and intermixed with rich hydrocarbons, 
 forms merely a mechanical mixture — no chemical affinity 
 existing between them — and, in consequence, the hydro- 
 carbons were deposited in the pipes before the gas reached 
 the consumers’ burners, whereby it was so much impoverished 
 and deteriorated as often to be next to worthless as an 
 illuminating agent. Thirdly : It was impossible to regulate 
 the supply of steam in proportion to the heat of the retort 
 where it was destined to be decomposed ; so that when there 
 was an excess of steam, nearly the whole passed off merely 
 superheated without being decomposed, to be afterwards 
 condensed into water ; so, under these circumstances, the 
 rich gases were delivered without the proper quantity of 
 hydrogen, and of course a beautiful light was the result. On 
 other occasions, when the water was successfully decomposed, 
 the hydrogen being in excess, the gas would be exceedingly 
 poor, possessing little illuminating power. Thus, one night 
 the light would be of great brilliancy, and the next of the 
 worst description. This irregularity was very fatal to the 
 method. 
 
 But one of the greatest objections was the cost of wear 
 and tear. Clay retorts, although most suitable on account 
 of being capable of sustaining that degree of heat essential 
 for the decomposition of water, could not be employed 
 
ON WATER GAS. 
 
 307 
 
 because of the leakage, the hydrogen being much more pene- 
 trating than coal gas. Therefore iron retorts only could be 
 used ; and these, by the combined action of the heat and 
 the oxygen absorbed by them from the water, were speedily 
 converted into a kind of plumbago ; they also thickened to a 
 great extent, thus presenting a large mass of non-conducting 
 material, which not only increased the fuel to an enormous 
 degree, but the retorts were of very short duration, so that 
 the wear and tear and fuel account added considerably to the 
 many other disadvantages. 
 
 One of the great arguments of Dr. Frankland in favour 
 of the hydrocarbon process was, that the hydrogen swept 
 out the whole of the carbon, and instead of this being 
 deposited in the retorts, it was carried to the burners for 
 consumption. This might probably be a consideration at 
 that period, but the improvements in carbonising coal, by 
 the employment of the exhauster, have reduced this deposit 
 to an unimportant amount. 
 
 It may be stated that the zeal, energy, and perseverance 
 displayed in endeavouring to carry this process to a successful 
 issue, merited a better result ; but the system was erroneous, 
 and a striking instance of the highly successful experiment 
 of the laboratory being commercially worthless when carried 
 into practice. 
 
 Hydrogen gas was employed by M. Gillard in another 
 manner. In this instance the gas issued from an argand 
 burner surmounted by a platinum wire cage which reached 
 a little above the dull hydrogen flame ; the wire cage 
 became incandescent, and a cylinder of intense light was 
 formed around it over the whole surface, the light being 
 obtained simply by the incandescence of the platinum wire. 
 Narbonne, and two or three other small towns in France 
 were lighted for some time by these means, but the great 
 expense of hydrogen caused it to be renounced. The light 
 hy this process, although intense, w T as neither agreeable nor 
 useful. With the view of obtaining hydrogen more economi- 
 cally, M. Gillard erected a cupola similar to those in iron 
 founderies ; this was filled with coke or charcoal, ignited, and 
 the fuel brought to a state of incandescence by a fan or 
 
308 
 
 ON THE RATING OF GAS-WORKS 
 
 blower ; after which (all passage to or from the atmosphere 
 being closed) steam was admitted at the lower part, and pas- 
 sing through the volume of fuel was decomposed, when the 
 hydrogen and carbonic acid with which it was impregnated 
 were withdrawn by an exhauster from the upper part of 
 the cupola. From time to time the supply of steam ceased, 
 and air was furnished by the blower as before, to bring the 
 fuel to the proper degree of temperature for the decomposition. 
 
 This plan, although much more economical than the retort 
 system, did not succeed ; the expense of manufacture was still 
 very excessive. Therefore it may be concluded that the 
 production of hydrogen gas by the decomposition of water is 
 neither advantageous nor economical, and whether applied to 
 be intermixed with rich gases, heating platinum wire, or being 
 intermixed with oxygen to produce the hydro-oxygen or 
 lime light, cannot at the present time compete with coal gas. 
 
 CHAPTER XXIV. 
 
 ON THE RATING OF GAS-WORKS IN PAROCHIAL ASSESS- 
 MENTS. 
 
 After many years of strife and contention, during which 
 extravagant statements have undoubtedly been put forth on 
 both sides of the question, a more rational and sober series of 
 conditions appears to have been agreed upon. The principle 
 is at least firmly established that every property, however 
 great, and however extensive may be its ramifications, is to 
 be rated on the rental which a tenant would give for it as a 
 whole from year to year, deducting therefrom such expenses 
 as will necessarily be incurred by the owner in order to com- 
 mand such a rental. 
 
 In the following discussion I wish to guard myself from 
 any imputation of advocacy on either side of the question. 
 All my inclinations lead me to lean to the side of public 
 companies associated together for purposes of enterprise, and 
 who at the same time are frequently entitled to rank as public 
 benefactors. I cannot, however, conceal from myself the fact, 
 
IN PAROCHIAL ASSESSMENTS. 
 
 309 
 
 that a great deal of misplaced indignation lias been displayed 
 of late years by public companies and their organs on the 
 subject of rating. They seem to have been especially irritated 
 at seeing their property assessed on the same principles as 
 other descriptions of property, and have sought to introduce 
 exceptions and modes of dealing with their particular case 
 which do not appear warranted by the law as it now stands. 
 
 I shall not discuss the justice of the present law of rating, 
 but simply endeavour to give, as clearly as I am able, my view 
 of the manner in which it should be carried out, and the way 
 in which gas property should be rated in proportion to other 
 property in the same parish. If powerful joint-stock com- 
 panies possessing a large interest in the soil, such as railway, 
 canal, gas, and water-works companies, would consider for a 
 moment the number of separate individuals which their 
 gigantic concern displaces^ and reflect how large an amount 
 a parish would derive from the separate rating of so many 
 individuals, they would see less reason than at present to 
 complain of the injustice of parochial rating. From a parlia- 
 mentary document which appeared a few years ago, it appears 
 that the London and Birmingham railway proper, 112 miles 
 in length, was rated to the relief of the poor on a net rate- 
 able value of £131,159. Now, this rateable value applies to 
 an expenditure of at least four millions sterling in works, 
 buildings, and other stationary property which is clearly 
 rateable, so that the value on which the railway is rated 
 would be about 3*3 per cent, on the fee-simple of the property 
 But conceive the same amount of four millions sterling in- 
 vested in buildings of any description, and it will be admitted 
 by most persons who have attended to the subject that such 
 a rating is far below that which would be applied to buildings ; 
 and that, in fact, a rateable value equal to 6 or 7 per cent, of 
 the value is by no means unusual. While, on the one hand, 
 it is highly unjust for public companies to be rated for a 
 mere local purpose at a higher proportionate rate than other 
 properties, it is also manifestly unfair that they should escape 
 local taxation to a greater extent than any other kind of 
 property. 
 
 In proceeding to rate any description of property extending 
 
310 
 
 ON THE RATING OF GAS-WORKS 
 
 into many different parishes, such as a gas-work, a railway, 
 a canal, or a water-work, it is necessary first to determine 
 the net rateable value of the whole, and then to apportion 
 this net rateable value amongst all the parishes in which the 
 works are situate. I shall first consider the mode of ascer- 
 taining the rateable value of the property as a whole, and 
 then proceed to the method of subdividing or apportioning 
 this amongst the parishes. 
 
 Now, in order to arrive at the rateable value of the whole, 
 we are clearly to be guided by the words of the Act 6th and 
 7th William IV. chap. 96, which enacts that property is to 
 be assessed first at that rent which it might reasonably be 
 expected to let for from year to year, and then that the net 
 rateable value is to be found by deducting from this annual 
 rent such expenses for insurance, repairs, &c., as will enable 
 the property to command such rent. The exact words of 
 the Act, which is commonly called the Parochial Assessment 
 Act, are as follows : — “ That no rate for the relief of the poor 
 in England and Wales shall be allowed by any justices, or be 
 of any force, which shall not be made upon an estimate of the 
 net annual value of the several hereditaments rated thereunto ; 
 that is to say, of the rent at which the same might reasonably 
 be expected to let, from year to year, free from all usual rates 
 and taxes, tithe commutation rent charge, if any, and 
 deducting therefrom the probable average annual cost of 
 repairs, insurance, and other, expenses, if any, necessary to 
 maintain them in a state to command such rent.” 
 
 The first thing therefore in rating a gas-work is to deter- 
 mine the rent at which it may be expected to let for from 
 year to year, and here immediately and directly arises the 
 necessity for a reference to the company’s balance sheet, in 
 order to find out the profit which the company is making. 
 It has happened in the absence of such a document, when 
 access to the company’s books has been refused from some 
 cause or other, that valuers have been required to form an 
 estimate of the annual value from independent calculations of 
 their own, in which the cost of manufacturing the gas is 
 deduced from certain data real or imaginary, and a profit 
 assumed as the amount realised by the company. I shall not 
 
IN PAROCHIAL ASSESSMENTS. 
 
 311 
 
 stop to inquire into the mode of so estimating the profits of 
 a gas-work, although when the amount of coal carbonised is 
 known, the selling price of gas being given, the locality 
 and other circumstances taken into consideration, a tolerably 
 fair approximation may be made. I am only desirous at 
 present to establish, as a foundation to proceed upon, that the 
 profit realised by the company in any one year is the basis 
 or ground-work from which the rateable value must be 
 derived. 
 
 This point should be clearly settled at the outset, because 
 it has been contended more or less ever since 1836, when the 
 Parochial Assessment Act passed, that such a mode of assess- 
 ment was unfair with respect to railways and similar works. 
 It has been said that in seeking to ascertain the profits of a 
 railway company you are seeking to rate them on profits , 
 which is expressly forbidden by a short Act which is passed 
 every session for the purpose of exempting stock in trade 
 from liability to be rated. But on the other hand it is to be 
 observed, that the inquiry into profits is rendered necessary 
 in order to ascertain what the property would let for, and 
 this is precisely that which is directed to be ascertained by 
 the Parochial Assessment Act. The necessity for inquiring 
 into profits is supported by every example that can be brought 
 to bear on the subject. 
 
 In the case of rating ordinary houses the gross annual 
 value is a very simple affair, because the house has generally 
 a tenant who does exactly pay a rent for it, and even if in 
 the landlord’s occupation, the value to let is easily inferred 
 from comparison with similar houses ; but when we come 
 even to the most simple case of premises deriving a peculiar 
 value from situation, manufacturing power, or any other 
 circumstances, we require to know immediately the amount 
 of profit which annually arises from such circumstances. 
 Thus we may know perfectly well, without any inquiry into 
 profits, what all the houses in any particular street will let 
 for ; but suppose one house to be fitted with a billiard-table 
 from which the tenant derives a profit, we shall require to 
 know the amount of this profit before we can estimate the 
 additional value which is conferred by the billiard-table. 
 
312 
 
 ON THE RATING OF GAS-WORKS 
 
 The same remark applies to peculiar situation and to 
 manufacturing power, as where machinery exists on the 
 premises. In all these cases, where the landlord holds or 
 occupies the property himself, we ought to know the profit 
 which he derives before we can possibly estimate the value 
 of the property to let from year to year. 
 
 Admitting then that the profit must be inquired into, there 
 are two ways of arriving at this — either by taking it from the 
 company’s books of account, or making an independent esti- 
 mate of what the profit ought to be. In the case of railway 
 companies, the business carried on is so extensive and com- 
 plicated that as a matter of necessity the parochial officers 
 and persons acting for them are compelled to take the profit 
 from the accounts of the company, usually from the accounts 
 published for their half-yearly meetings. In the case of gas 
 companies, however, some of which are not under the most 
 efficient management, it is not unusual for valuers to make 
 their own estimate of the profits on certain known data , 
 which are perhaps admitted on the part of the gas company. 
 I shall not at present enter into the mode of estimating the 
 productive power', and consequently the profit of a gas com- 
 pany, but suppose that this has been ascertained by one or 
 other of the means pointed out, and that the profit is found 
 to consist of a certain sum which remains after deducting the 
 total expenditure of the year from the gross receipts during 
 the same period. 
 
 We have now arrived at the profit made by the company 
 whilst the works are in their own occupation, but this is not 
 the sum which a tenant will give for them, because he must 
 not only have a certain sum left for himself as a remuneration 
 for his time and superintendence, but must have interest for 
 the capital employed to carry on the works. 
 
 The amount and nature of these arbitrary allowances for 
 the tenant have given rise to great disputes, and the utmost 
 variety of opinion is entertained on the subject. It appears 
 to be an admitted principle on all sides that the tenant is to 
 be allowed a certain amount of capital to carry on the works, 
 that is, to pay for coal, lime, wages, &c., until his returns are 
 received for gas and coke sold; and also that he is to be 
 
IN PAROCHIAL ASSESSMENTS. 
 
 313 
 
 allowed for capital corresponding in amount with the present 
 value of such machinery as comes under the denomination of 
 stock in trade, and which cannot be rated as forming a part 
 of the premises, or an hereditament attached to the soil. 
 
 On the part of the gas company the whole yearly expen- 
 diture is first deducted from the gross receipts, including 
 such items as wear and tear of retorts, loss by meters, rates 
 and taxes, directors’ and auditors’ salaries, bad debts, &c. 
 The balance which remains is then subject to what are 
 termed arbitrary allowances for tenant, in which his capital is 
 made to consist of the following items : — 
 
 1. Capital required to enable him to carry on the works, 
 usually estimated by valuers for the companies at about half 
 the gross expenses for one year. 
 
 2. The present value of the meters, retorts, and other stock 
 in trade. 
 
 On the capital so arrived at, it is assumed that the tenant 
 would require 5 per cent, for interest and 12J per cent, for 
 profit, which amount is therefore deducted from the gross 
 value as an arbitrary allowance to the tenant. 
 
 On the other hand, the parties usually employed to value 
 for the parishes, contending that directors’ and auditors’ 
 salaries being already allowed for in the expenses, make this 
 a set-off against the remuneration of the tenant. Consider- 
 ing further the perfect security for payment which the Act 
 of Parliament gives to most gas companies, the means which 
 they have of enforcing payment, and the small amount of 
 risk incurred in carrying on their business, they contend that 
 such an allowance of 17^- per. cent, for capital is excessive, 
 and ought not to be more than 10 or at most 15 per cent. 
 Then as to the amount of capital, they seem to have gene- 
 rally allowed the retorts to be stock in trade, but not the 
 meters, which they consider fixtures to the mains, and there- 
 fore subject to be rated. 
 
 An example of estimates formed on these varying prin- 
 ciples will be shortly given, from which it will be seen how 
 widely these arbitrary deductions vary according to the 
 views adopted by the valuers. 
 
 I now come to the class of deductions comprised under tho 
 P 
 
314 
 
 ON THE RATING OF GAS-WORKS 
 
 head of statutable allowances, comprehending all those (such 
 as rates, taxes, insurances, and repairs) which are necessary 
 to enable the premises to command the rent assumed. Here 
 the valuers for gas companies have sought to bring in charges 
 for repairs, or rather for restorations, which are said to be 
 necessary, in addition to those which appear in the annual 
 current accounts. For instance, they claim an annual allow- 
 ance for the repair of buildings, although the accounts include 
 every farthing which has been expended in such repairs. 
 
 They also claim an allowance for insurance of buildings 
 beyond any amount which is actually paid for such a pur- 
 pose. Besides which they claim an allowance of 2 per cent, 
 on the value of all their trade fixtures and utensils, and of 1J 
 or 2 per cent, on the value of all the mains, for the reproduc- 
 tion of these when worn out. The valuers for parishes, ou 
 the other hand, entirely dispute these allowances, and con- 
 tend that the current expenses provide for such reproduction 
 by having everything renewed as fast as it is worn out and 
 requires to be replaced. 
 
 Some years ago, in the rating of railways, very extrava- 
 gant allowances were claimed, on the same principle, to cover 
 the reproduction of the rolling stock and of the permanent 
 way. It was, however, frequently suggested that if any 
 provision were necessary for such a purpose, the railway 
 company should itself set aside a sum annually, by way of 
 sinking fund, to cover such an expense when found necessary. 
 In certain cases where no such fund was set aside by the 
 railway company, the allowance for reproduction was refused 
 on the rate being appealed against. There is still, however, 
 a difference amongst railway engineers as to the necessity 
 for a depreciation fund. The London and Brighton Railway 
 Company, acting probably under the advice of their able 
 chairman, Mr. Lang, who possesses a vast amount of practical 
 experience and valuable statistical knowledge, has been in 
 the habit for some years of setting aside a sum out of its 
 receipts to form a depreciation fund. On the other hand, 
 such a fund has been declared altogether unnecessary by one 
 of the most eminent and accomplished railway engineers of 
 the day, who has devoted himself to every question of rail- 
 
IN PAROCHIAL ASSESSMENTS. 
 
 315 
 
 way politics with an energy and industry peculiarly his own. 
 I need scarcely say that I allude to the originator of the 
 broad gauge, who has publicly declared that the current 
 accounts of the Great Western Railway include such ex- 
 penses as are necessary, from time to time, for keeping in 
 perfect order both the rolling stock and the permanent way, 
 and that no annual reserve in the shape of a depreciation fund 
 is necessary for their maintenance. 
 
 I am aware that there are many rating cases which are 
 tried on appeal at quarter sessions, where an intimation i3 
 given by the bench that some allowance for depreciation 
 should be made to the company beyond that which appears 
 in their accounts. In addition to this, in the valuing of 
 houses, manufactories, and many other descriptions of pro- 
 perty, where no accounts of repairs have been kept, or where 
 it appears clear that a charge for restoration would accrue 
 suddenly at some future time, and cannot be provided for by 
 annual repairs and restoration, it may be necessary to calcu- 
 late on sound principles what the allowance should be for 
 such a purpose. It will not be sufficient in such a case to 
 assume any mere arbitrary allowance on the cost, such as \\ f 
 2, or 5 per cent., all of which sums have been claimed for 
 reproduction, but it must actually be ascertained what sum 
 under the given conditions of the question will be an equi- 
 table allowance for the purpose. There are two elements 
 which must be assumed in any case of this kind ; first, the 
 value of the object to be restored, and the period or distance 
 of time at which the restoration is to be made. The value 
 must not be the original value of the object when first 
 erected, but its value at the time of making the rate; and 
 when once the sum to be set aside annually is determined, it 
 will be the same year after year, because, although the value 
 of the object will diminish yearly, so also, in the same propor- 
 tion, will diminish the number of years during which the 
 annual sum is to be set aside. The principle I am now con- 
 tending for is this, that the annual sum to be set aside is that 
 sum which at compound interest will amount in the assumed 
 number of years to the whole sum required at the end 
 of that period to effect the restoration. For instance, 
 
 p 2 
 
310 ON THE RATING OF GAS-WORKS 
 
 suppose a building or any other object whose present value 
 is £1,000 should be assumed to last thirty years, when an 
 amount of £1,000 must be employed to restore it; then, I 
 say, the annual sum to be put aside is that which, at com- 
 pound interest, at 3 per cent., will amount in thirty years to 
 £1,000. Now, it appears from the tables of compound inte- 
 rest that£l per annum invested at compound interest during 
 thirty years will amount at the end of that time to £47. 
 Hence it follows, if we divide 1,000 by 47. we shall have the 
 sum which, being invested annually at compound interest, 
 
 will at the end of that time produce £1,000. Then — 
 
 = £21 5s. 8d., the sum to be invested annually. This 
 w r ould amount to rather more than 2 per cent., which is the 
 proper allowance when the duration is estimated at thirty 
 years. 
 
 When a period of tw r enty years is taken for the duration 
 of an object, an allowance of nearly 4 per cent, must be 
 made. 
 
 When the period is 30 years, 2 per cent. 
 
 „ 40 ‘ „ 1*3 „ 
 
 50 „ *88 „ 
 
 The following estimate, made by Mr. Lee, of the net rate- 
 able value of the Phoenix Gas Company, forms a good 
 example of the mode usually adopted by the valuers of gas 
 companies for assessing the rateable value. This valuation 
 was made in 1849 on the occasion of an appeal by the Phoenix 
 Gas Company against the rate in the parish of Greenwich. 
 
 £ s. d. 
 
 Net balance for 12 months, taken from the company’s 
 
 books 21,964 12 0 
 
 Arbitrary deductions to arrive at the gross estimated 
 
 rental. 
 
 Floating capital employed by tenant, £ s. d. 
 assumed equal to six months’ ex- 
 penses 33,210 0 0 
 
 Present value of meters, the cost being 
 
 £25,000 15,000 0 0 
 
 Present value of retorts 7,525 0 0 
 
 Total amount of tenant’s capital . £55,735 0 0 
 
IN PAROCHIAL ASSESSMENTS. 
 
 317 
 
 £ s. d. £ s. d. 
 Brought forward .... 21,964 12 0 
 
 5 per cent, for interest on £55,735 is . 2,786 0 0 
 
 J2£ per cent, for tenant’s profit on 
 £55,735 6,966 0 0 
 
 Amount of interest and tenant’s profit for one year . 9,752 0 0 
 
 Gross estimated rental 12,21212 0 
 
 Statutable deductions. 
 
 Bates and taxes previously deducted in arriving at not 
 balance ; annual repairs of buildings previously de- 
 ducted. 
 
 Insurance on buildings, value £65,054, £ s. d . 
 
 at 5s 162 0 0 
 
 2 per cent, for reproducing the follow- 
 ing:— 
 
 £ s. d. 
 
 Trade fixtures, value 39,672 0 0 
 Utensils .... 12,94/5 0 0 
 
 Mains in the stations 6,271 0 0 
 
 Street mains . . . 105,760 0 0 
 
 £164,648 0 0 
 
 2 per cent, on £164,648 3,292 0 0 
 
 Total deduction for renewal and insurance . . . 3,454 0 0 
 
 Net rateable value of the whole property, the 
 
 value being £278,998 £8,758 12 0 
 
 It appears that the valuers for the parish during this appeal 
 did not treat the production of the Phoenix Gas-works as a 
 whole, but confined their estimates to the production of the 
 Greenwich Station alone, whereas the company has also 
 manufacturing stations at Vauxhall and at Bankside. In 
 consequence of this, no comparison can be made between 
 the net rateable values arrived at by the two parties, treating 
 the works as a whole. Mr. Penfold, however, in his work 
 on Eating, has published a statement of net rateable value 
 for the whole works, founded on the basis of the company's 
 own rental, and on arbitrary allowances, according to 
 Mr. Barlow’s statement of expenses for manufacturing gas. 
 This statement is taken from an able Eeport made by 
 Mr. Barlow in 1849 to the Directors of the City of London 
 Gas Company. In his Report, Mr. Barlow analyses with 
 
318 
 
 ON THE RATING OF GAS-WORKS 
 
 great minuteness the prospects of the Great Central Gas 
 Consumers’ Company. He investigates the cost of every 
 item of gas manufacture under two distinct heads, 'production 
 and distribution , making the total cost of production amount 
 to 20 # 64cZ. per 1,000 feet of gas made, and the expense of 
 distribution equal to 13*51c?. per 1,000. Mr. Penfold, con- 
 sidering Mr. Barlow as the especial advocate of the then 
 existing companies, and interested in proving the cost of gas- 
 making to be as high as possible, considers such statements 
 fair evidence as against any gas company on the question 
 under discussion. 
 
 Using the data before explained, Mr, Penfold makes 
 the net rateable value of the whole of the Phoenix 
 
 Company’s gas-works £18,312 
 
 And substituting Mr. Croll’s cost of manufacturing 
 gas, as given in evidence before the Central Gas 
 Committee, he makes the net rateable valuable of 
 
 the whole 28,455 
 
 Mr. Lee’s valuation of the rateable value being . . 8,758 
 
 We shall present one other case in which the author was 
 himself engaged, and Mr. Lee valued for the gas company. 
 This was the case of the British Gas Company and the parish 
 of Ratcliff. Mr. Lee’s valuation in this case was nearly on 
 the same basis as in the Greenwich case, except that the esti- 
 mates claimed only 1\ instead of 2 per cent, for the reproduc- 
 tion of the mains. The following is Mr. Lee’s valuation : — 
 
 Or. £ s. d. £ s. d. 
 
 Total rental for gas-light . . . . ; 21,188 0 0 
 
 Cash for coke and ammonia .... 4,514 0 0 
 
 Total receipts for 12 months 
 
 Dr. 
 
 £ 
 
 s. 
 
 d . 
 
 Coals, 12,322J tons used 
 
 
 
 
 (at 145. 10 \d.) . . . 
 
 9,153 
 
 0 
 
 0 
 
 Lime used for purifying 
 
 267 
 
 0 
 
 0 
 
 Working process wages 
 
 5,092 
 
 0 
 
 0 
 
 Wear and tear of retorts, 
 
 
 
 
 &c 
 
 2,020 
 
 0 
 
 0 
 
 Meter repairs and 
 fixing .... £882 
 Meter rent received 400 
 
 Loss 482 0 0 
 
 25,732 0 ft 
 
 Carried forward 17,014 0 0 
 
 25,732 0 0 
 
IN PAROCHIAL ASSESSMENTS. 
 
 319 
 
 £ 5 . 
 
 Brought forward 17,014 0 
 
 Bates and taxes (last 
 year, 1848) .... 650 0 
 
 (Bates in 1849 are larger.) 
 
 Office expenses and clerks’ 
 
 salaries 742 0 
 
 Directors’ salaries. . . 500 0 
 
 Ordinary law expenses . 70 0 
 
 Interest on borrowed 
 capital . . . £1,395 
 
 Bad debts and over- 
 charges . . . . 400 0 
 
 d. 
 
 0 
 
 0 
 
 0 
 
 0 
 
 0 
 
 0 
 
 £ s. d. 
 
 25,732 0 0 
 
 19,376 0 0 
 
 Net balance for 12 months . . . 6,356 0 0 
 
 Deductions to arrive at 
 the gross estimated 
 value 5 per cent, on 
 the capital* necessarily 
 employed by a tenant 11,500 C 0 
 Ditto on the present 
 value of meters (the 
 cost being £5,640) . . 3,640 0 0 
 
 Ditto on the present 
 value of retorts (cost 
 £4,680) 2,420 0 0 
 
 Amount of tenant’s 
 capital .... 17,560 0 0 
 5 per cent on the above is .... 
 Amount of tenant’s profit, being 12J- 
 per cent, on the above £17,560 capital 
 
 £ s. d. 
 878 0 0 
 
 2,195 0 0 
 
 Amount of interest and tenant’s 
 profit for 12 months .... 
 
 Gross estimated rental of the 
 whole property ...... 
 
 Statutable deductions. 
 
 The rates and taxes are before deducted. 
 Annual average repairs of buildings . 
 
 Insurance on buildings 
 
 For renewal or reproducing trade fix- 
 tures and utensils, their value being 
 £16,847 (meters not included), at 
 2 per cent 
 
 3,073 0 0 
 3,283 0 0 
 
 390 0 0 
 106 0 0 
 
 336 0 0 
 
 Carried forward 832 0 0 3,383 0 0 
 
 * The capital here assumed is considerably more than six months’ 
 expenses, and is nearly equal to six months’ gross receipts. 
 
320 
 
 ON THE RATING OF GAS-WORKS 
 
 Bi ought forward .... 
 
 For renewal or reproducing the mains 
 on the stations, and the street mains, 
 their value being £24,453, at l£ per 
 cent 
 
 £ s. d. £ s. d. 
 832 0 0 3,383 0 0 
 
 367 0 0 
 
 Total of repairs, insurance, and renewal 
 
 1,199 0 0 
 
 Net rateable value of the whole property . . . £2,184 0 0 
 
 It being considered that this rateable value was too small, 
 having regard to the magnitude and capacity of the works, 
 the author was called in by the parish at the suggestion of 
 Mr. Penfold, who was one of the arbitrators, and after going 
 through the works and minutely considering the Company’s 
 evidence to see what parts could be adopted as reasonable 
 and fair, the result of his investigation was the following 
 estimate : — 
 
 Net rateable Value of all the Works and Mains. 
 
 £ s. d. 
 
 Gross revenue, as per statement A 24,172 17 3 
 
 Production account . 
 
 £ s. d. £ s. d. 
 
 Coal, as per evidence . . 9,153 0 0 
 
 Labour of distilling 12,322 
 tons of coal, as per state- 
 ment B 2,261 5 0 
 
 Wear and tear of retorts, 
 as per statement C . . 1,333 13 0 
 
 Expense of lime for puri- 
 fying, 12,323 bushels, 
 at 4 d 205 8 0 
 
 12,953 6 0 
 
 Less residual products, 
 as per statement D . 4,601 13 4 
 
 Cost of distribution, as per statement E 
 Statutable allowances, as per .state- 
 ment E 
 
 Arbitrary deduction for interest and 
 tenant’s profit, £10,000, at 15 per 
 cent., as per statement G . . . . 
 
 8,351 12 8 
 3,276 7 3 
 
 1,219 18 0 
 
 1,500 0 0 
 
 Deduct rates and taxes, as per company’s statement 
 
 14,347 17 11 
 
 9,824 19 4 
 
 650 0 0 
 
 Net rateable value of the whole property . . . £9,174 19 4 
 
IN PAROCHIAL ASSESSMENTS. 
 
 321 
 
 A. — Estimate of Gross Revenue. 
 
 12,322^ tons of coal carbonised per annum, each ton 
 assumed to yield 9,200 cubic feet of gas. 
 
 Then 12,322J X 9,200 = 113,367,000 
 
 Less one-fourth for leakage 28,341,750 
 
 Total quantity to be sold .... 85,025,250 
 
 From this deduct consumption 
 of 1,264 public lights, each 
 at 50 feet per night, making 
 1,264 X 50 X 365 = . . 23,068,000 
 
 Deduct also quantity used in 
 
 works, as per evidence . . 1,000,000 
 
 24,068,000 
 
 w — —————— £ s i 
 
 Private consumption 60,957,250 j jg 237 2 0 
 
 at 6s. j * 
 
 Receipts for public lights, as per company’s evidence . 5,885 15 3 
 
 , £24,172 17 3 
 
 B. — Estimate of Expense for the Larottr of manufacturing Gas 
 FROM 12,323 TONS OF COAL. 
 
 Salary of superintendent £200 0 0 
 
 Foreman, at 3 6s. per week 93 12 0 
 
 Two foremen of stokers, at 30s. per week each .... 156 0 0 
 
 Twenty ordinary stokers, at 24s. each 1,248 0 0 
 
 Wheeling coal, 12,323 tons, at 3 d. 154 1 0 
 
 Two purifying men, at 24s. each 124 16 0 
 
 Valve man, at 28s 72160 
 
 Storekeeper . 8000 
 
 Coke clerk 8000 
 
 Gatekeeper 5200 
 
 £2,261 5 0 
 
 O. — Wear and Tear of Retorts. 
 
 In this estimate it is assumed that each retort will be 
 worn out, and require to be taken down and reset, after 
 producing 700,000 cube feet of gas. Hence the number of 
 
 retorts required per annum will be 
 
 113,367,000 
 
 700,000 
 
 162 
 
 retorts, which are assumed to be of cast iron, weighing 16 
 cwt. each. 
 
 £ s. d. 
 
 Hence 162 retorts, at £5 .... 810 0 0 
 
 Taking down 162 old retorts, breaking the connections, 
 
 and renewing old materials, 162 at 4s 32 8 0 
 
 p 3 
 
 Carried forward 
 
 842 8 0 
 
322 
 
 ON THE RATING OF GAS-WORKS 
 
 £ 8. d. 
 
 Brought forward 842 8 0 
 
 Bricklayers’ w’ages for re-setting retorts, 162 at 12 s. 6d. 101 5 0 
 
 Fire-clay and fire-bricks used in re-setting retorts, and 
 
 in repairing furnaces, 162 at 20s 16200 
 
 Making good connections to hydraulic main .... 26 0 0 
 
 Bolts and cement for new connections, wear and tear of 
 ash-pit pans, furnace-doors and bars, ears and cross- 
 bars, barrows, scoops, shovels, brooms, &c., 162 at 10s. 81 0 0 
 
 1,212 13 0 
 
 Allowance for contingencies, defective retorts, &c., 10 per 
 
 cent 121 0 0 
 
 £1,333 13 0 
 
 No deduction is here made for the sale of the old retorts. 
 
 D. — Residual Products. 
 
 Total coal used 12,322 tons. 
 
 Making 12,322 chaldrons of coke. 
 
 Used for carbonising, one-third 4,107 
 
 Remaining for sale . . . . 8,215 chaldrons. 
 
 £ s. d. 
 
 8,215 chaldrons, at 10s 4,107 10 0 
 
 100 tons of coal will yield 8 chaldrons of breeze, to be 
 sold for brick-making, at 3s. per chaldron. 
 
 12 322 X 8 
 
 Hence — H[oo ~ 985, at 3s . . 147 15 0 
 
 Each ton of coal will yield 10 gallons of gas tar. 
 
 Hence 123,220 gallons, at 1 d 513 8 4 
 
 4,768 13 4 
 
 Deductions . £ s. d. 
 
 Filling 9,200 chaldrons of coke and breeze, 
 
 at 3 d, 115 0 0 
 
 Labourers delivering tar and ammoniacal 
 
 liquor 5200 
 
 167 0 0 
 
 £4,601 13 4 
 
 E.— Expenses op Distribution. 
 
 £ s. d. 
 
 Lighting and repairing 1,264 public lamps, at 20s. . . 1,264 0 0 
 
 Collection and bad debts, at 3 per cent, on rental of 
 
 £24,000 720 0 0 
 
 Law expenses, stationery, and incidental expenses, 
 
 113,367 at \d. 472 7 3 
 
 Engineer, secretary, clerks, and inspectors 820 0 0 
 
 £3,276 7 3 
 
IN PAROCHIAL ASSESSMENTS. 
 
 323 
 
 Engineer £200 
 
 Secretary ...... 200 
 
 Two clerks 150 
 
 Three inspectors . . . . 270 
 
 £820 
 
 .—Statutable Allowances. 
 
 £ 5 . d. 
 
 Insurance of buildings, and annual repairs of buildings 
 
 and apparatus 50000 
 
 Renewal or reproduction of trade fixtures, valued at 
 
 £17,644, at 2 per cent.* 352 18 0 
 
 Renewal of mains, valued at £24,453, at 1J per cent.* 367 0 0 
 
 £1,219 18 0 
 
 G. — Estimate of Capital required by a Tenant. 
 
 Coal in stock, 2,000 tons, at 15s 1,500 0 0 
 
 £ s. d. 
 
 One year’s consumption of coal . . . .9,153 0 0 
 
 One year’s wages for manufacturing, as 
 
 per statement B 2,261 5 0 
 
 One year’s wear and tear of retorts, as per 
 
 statement C 1,333 13 0 
 
 One year’s expenses of distribution, as per 
 
 statement E 3,276 7 3 
 
 One year’s maintenance of works, repairs, 
 insurance, &c 500 0 0 
 
 16,524 5 3 
 
 Deduct one year’s receipts for sale of coke 4,601 13 4 
 
 £11,922 11 11 
 
 The tenant would have to provide for half-a-j-oar’s 
 
 payment, or L — 5,961 10 0 
 
 Assumed value of retort, as per evidence 2,420 0 0 
 
 £9,881 10 0 
 
 DIVISION OF THE NET RATEABLE VALUE BETWEEN THE 
 SEVERAL PARISHES. 
 
 We now come to the second branch of inquiry: namely 
 the mode of apportioning the net rateable value, as deter- 
 
 * These allowances were made because in former cases they had 
 been decided at quarter sessions. The amounts being small, it was 
 not thought advisable to complicate the case by contending for the 
 principle of a sinking fund, which, as already explained, is the proper 
 way to estimate costs of reproduction. 
 
324 DIVISION OF THE NET RATEABLE VALUE 
 
 mined for the whole gas-works, amongst the several parishes 
 through which the mains extend. Here again we find quite 
 as great a variety of opinion as on the other subject. Even 
 the judgments delivered by the Court of Queen’s Bench, the 
 highest court of appeal to which rating cases have been 
 carried, seem to have undergone some change year after 
 year since the passing of the Parochial Assessment Act. It 
 appears to be clearly decided, in the case of the Queen v 
 Cambridge Gas Lighting Company, that the rateable value 
 is not to be divided in proportion to the receipts for gas in 
 each parish ; and Lord Denman, in his judgment in this 
 case, quoted a parish through which the New River passed, 
 and in which no profits accrued to the Company, yet the 
 New River works in this parish were rated, and properly so, 
 at <£300, because the apparatus in the parish contributed to 
 the whole value to let, although no receipts within the parish 
 itself were derived from the apparatus lying within it. So 
 it will often happen in the case of gas-works that mains may 
 pass through a parish without any service-pipes being affixed 
 to them, without supplying any gas in the parish, and con- 
 sequently not yielding any receipts. But the works are 
 nevertheless to be rated in this parish because they carry 
 gas which passes through them for the supplying of other 
 parishes where the company receives payment for its gas. 
 Some of the judgments even seem to have inclined to the 
 opinion, especially in the case of railways, that the total 
 rateable value should be divided in proportion to the mileage 
 or length of line passing through each parish. This division 
 however, would usually be very unjust alike for railways, 
 gas-works, and all similar undertakings. In each case the 
 most remote and thinly inhabited parishes would reap far 
 more than their share, while metropolitan parishes, and 
 chiefly those nearest to the principal termini or principal 
 sites of manufacture, would be injured in a proportionate 
 degree. Other decisions, however, and those of a more 
 recent date, have supported an opposite principle, — namely, 
 that of dividing the net rateable value of the whole in pro- 
 portion to the quantity of apparatus in each parish. Lord 
 Denman, in his judgment in the case of the Queen v. the 
 
BETWEEN THE SEVERAL PARISHES. 
 
 325 
 
 Cambridge Gas-Light Company, speaking of the division 
 amongst the parishes, says, “ We are aware of no rule which 
 can be laid down as to the amount, except that it must be 
 in proportion to the quantity of apparatus situate in each 
 parish.” 
 
 In the next case of importance, namely, that of the Queen 
 v. the South-Western Kailway Company, a somewhat clearer 
 principle was expressed ; and in the case of railways it was 
 decided that the division should be in proportion to the 
 earnings in each parish, having first deducted from the net 
 rateable value of the whole the rateable value of the stations, 
 which are separately rated in the parishes in which they are 
 situated. Now in the case of a railway this mode of division 
 is quite practicable, and no parish would be excluded from 
 its just proportion of the whole assessment, even though no 
 receipts are actually takep in it. Suppose a parish situate 
 between two stations A and B, then the whole of the traffic 
 passing from A to B and vice versa will pass through the 
 parish. The parish accordingly will be entitled to its pro- 
 portion of the receipts taken for traffic between A and B in 
 proportion to its length, so that the case is amply provided 
 for in which a parish has no station, and in which conse- 
 quently no receipts are taken by the Company. 
 
 The case is equally simple when the parish contains a 
 station ; the net rateable value here being a proportion 
 according to the mileage of the receipts between the station in 
 the parish and that on each side of it, with the addition of a 
 sum for the station itself. It would lead us too far out cf 
 our way and be altogether inapplieable in this work to go 
 further into the mode of dealing with the railway stations, 
 and separating their rateable value from that of the railway 
 proper ; and we must therefore confine our attention more 
 immediately to the case of gas-works. Here, however, the 
 same general principle prevails for separating the works, — 
 that is, all the rateable apparatus at the head-quarters or 
 manufacturing establishment from the pipes or mains extend- 
 ing through the streets.. No satisfactory or even practicable 
 mode of doing this has ever been suggested, except that 
 arising from the cost or value of the works as compared with 
 
326 DIVISION OF THE NET R VTEABLE VALUE 
 
 tli at of the whole property, worhs and mains together. We 
 shall suppose the net rateable value of the whole to have 
 been arrived at, and, in order to find the separate part of this 
 chargeable to the works and to the mains, we must have an 
 estimate of the present value of the works and of the mains 
 separately. Then we have this proportion ! — 
 
 As the present value of the works and mains together is 
 to the net rateable value of the whole, so is the present 
 value of the works to the net rateable value of the works. 
 In the same way the net rateable value of the mains is found 
 by substituting the present value of the mains for that of the 
 works in the third and fourth terms of this proportion. 
 
 The principal station or manufacturing site of a gas esta- 
 blishment is commonly at least equal in value to that of 
 the mains, so that in this simple mode we get rid of half the 
 rateable value by apportioning it to that parish in which 
 the manufacturing station is situate. If there be more than 
 one station the division is equally simple, each station being 
 debited with its proportionate rateable value according to 
 its present worth, as compared with the worth of the whole 
 property. 
 
 We have yet a further sum, however, to divide amongst 
 the mains, and perhaps this division has given rise to more 
 contention than any other question connected with the 
 rating of gas-works. In the case of the Phoenix Company 
 and the Parish of Greenwich, the Court of Quarter Sessions 
 decided that the division was to be made in proportion to 
 the square yards of ground occupied by the mains in each 
 parish. Now, with great submission to the learned Bench 
 of Magistrates, this decision was simply absurd, because the 
 square yards of ground occupied are neither a measure of 
 the quantity of apparatus, nor a measure of the earnings, 
 nor a measure of the capacity of the mains. This mode of 
 distributing the rateable value has the effect of giving an 
 enormous advantage to the remote parishes, and in a pro- 
 portionate degree injuring those which are nearest to the 
 fountain-head, and which first distribute the gas before it 
 can be taken out of the mains. 
 
 Another principle of division which has been adopted is 
 
BETWEEN THE SEVERAL PARISHES. 
 
 327 
 
 also fallacious, but not to the same extent — namely, that of 
 dividing the rateable value according to the cubic yards of 
 main in each parish. This principle makes a perfectly cor- 
 rect division according to the quantity of apparatus, but not 
 according to earnings, which by the latest decision is clearly 
 intended to be the basis of the subdivision. The error is of 
 the same nature as the one allowed by the Quarter Sessions 
 in the Phoenix case — namely, one of excess for the remote 
 parishes, at the expense of those near the centre of distribu- 
 tion. The principle, in fact, of dividing according to cubical 
 capacity of the mains is only correct on the supposition that 
 a main of a given area will deliver the same quantity of gas 
 at all distances from the gasholder, which we know is very 
 far from being the fact. Every one knows that a 12-inch 
 main within 100 yards of the gasholder will pass a great 
 deal more gas than the same main at the distance of a mile. 
 The principle in question would also require this theoretical 
 condition — namely, that the mains at the extremities of the 
 company’s district should be attenuated to such dimensions 
 as just to deliver the gas required for present consumption 
 with the requisite pressure ; but this is notoriously not so, 
 for with a view to extensions the mains are purposely not so 
 much contracted as they otherwise might be. The effect of 
 all this is, that this mode of subdivision does not give to the 
 mains their proportionate value as parts of the apparatus in 
 the arterial parishes, and gives too much value to those at a 
 distance. It divides the rateable value in proportion to 
 quantity of apparatus, not with reference to earnings, nor 
 with reference to capacity for earning, or contributing to the 
 whole earnings of the concern. 
 
 I am now bound to explain the mode in which I propose 
 to subdivide the rateable value amongst the mains, for which 
 purpose I must have the cubical contents of all the mains, 
 the cubical contents in the particular parish, the quantity of 
 gas supplied in that parish, and the annual receipts for that 
 gas. Then I should calculate the size of main which would 
 be required simply for the delivery of the quantity of gas 
 consumed in the parish, and consider the extra size of the 
 main entitled to a further allowance for contributing to the 
 
328 
 
 DIVISION OF THE NET RATEABLE VALUE 
 
 earnings of the parishes lying beyond. Thus, I would 
 say — 
 
 As the whole receipts are to the rateable value of the whole, 
 so are the receipts in the parish to the rateable value of the 
 mains in respect of receipts within the parish. 
 
 Then, to find the additional rating for the part contributed 
 by the mains towards the receipts in other parishes, I would 
 say— 
 
 As the cubical contents of all the mains is to the extra 
 cubical contents of main in the parish beyond what would 
 be necessary for the supply of the parish, so is the rateable 
 value of all the mains to the extra rateable value of mains in 
 the parish. The fourth terms in each of these proportions 
 being added together would give, as I conceive, the whole 
 rateable value of the mains in any parish. 
 
 I am afraid of extending this subject of rating to too great 
 a length, as it might be wearisome to many of my readers. 
 At the same time, the subject possesses much interest for gas 
 companies, who would in many cases fare better if they did 
 not attempt to shroud this affair in such impenetrable mys- 
 tery. This air of mystery is often apt to occasion a sus- 
 picion of far greater profit than that really derived. In all 
 such cases fair play to the parishes is to be insisted on ; let 
 each have its proper share, and let each have such means of 
 information as will enable its officers to make assessments on 
 a sound basis. 
 
 It has not occurred to me now for the first time, consider- 
 ing the many complicated interests which have to be assessed 
 in these days of progressive improvement, that it would be 
 desirable if some public officer were appointed to make an 
 assessment every year of the property in gas-works, canals, 
 railways, &c., rateable to the relief of the poor. Such an 
 assessment would require to be varied every year, but the 
 principle of division once settled would be permanent. A 
 vast amount of litigation would be thus saved, and in the 
 end all parties would find it much more satisfactory than the 
 present blindfold system. 
 
INDEX. 
 
 Accum and others engage in ex- 
 periments on gas-lighting, 14. 
 
 Air, mixture of, with gas dimin- 
 ishes the light, 215. 
 
 Air condenser, 143. 
 
 Ammonia, its composition and 
 origin, 46 ; Mr. Cr oil’s process 
 for separating, 170 ; salts of, 
 manufactured from ammoniacal 
 liquor, 174; sulphate of, yielded 
 by the liquor drawn from the 
 purifiers in Croll’s process, 174; 
 fertilising power of, 174. 
 
 Ammoniacal liquor, its value for 
 agricultural purposes, 46 ; puri- 
 fication by means of, 153 ; Prus- 
 sian blue made from, 296; price 
 of, 149. 
 
 Analysis and affinity described, 
 37. 
 
 Annual assessment of railways, 
 canals, gas-works, &c., proposed, 
 329. 
 
 Apparatus, iron, complete for gas- 
 works, specification of, 198. 
 
 Arbitrary allowances in rating 
 gas-works, 312. 
 
 Arbitrary allowances for repro- 
 duction, 316. 
 
 Ar bitrary allowances made by Mr. 
 Lee in rating cases, 317. 
 
 Author, valuation by him in a 
 rating case, 321. 
 
 Bachhoffner’s polytechnic fire, 
 304. 
 
 Barlow’s Report to the City of 
 London Gas Company, 146 ; 
 estimate for the erection of 
 
 retorts, 85 ; dimensions and 
 estimate for a large retort- 
 house, 85 ; estimate for con- 
 densers, 146 ; estimates of cost 
 of purification, 166 ; his table 
 of the discharge of gas from 
 pipes of various dimensions and 
 at different pressures, 238. 
 
 Bitumen, springs of, described by 
 Herodotus, 4. 
 
 Bituminous strata, 4. 
 
 Bituminous coal, gas arising from 
 beds of, in China, 5. 
 
 Black coal, 51. 
 
 Boghead cannel, 56. 
 
 Boghead cannel, per-centage of 
 volatile matter in, 54; quality 
 of gas produced from, 288. 
 
 Breeze, the use of, 294. 
 
 Brick retorts, Grafton’s, 100 ; 
 Clift’s, 101 ; Spinney’s, 101 ; 
 Winsor’s patent, 100. 
 
 Brick tanks for gas-holders, 183 ; 
 description of, 184 ; specifica- 
 tions of, 186, 188. 
 
 British Gas Company and the 
 parish of Ratcliff, 318. 
 
 Bromine test, on the, 373. 
 
 Bromine, mode of operating with, 
 and amount of condensation, 
 274. 
 
 Br unton’s retort, description of, 
 92. 
 
 Buildings in gas-works; retort- 
 house, 82 ; coke vault, 82 ; coal 
 store, 87 ; purifying house, 87 ; 
 engine house, 88 ; station meter 
 house, 88 ; chimney, 89. 
 
 Bunsen photometer, 276; engrav- 
 
330 
 
 I7.1DEX. 
 
 ings of the, 278, 279; method 
 of preparing the disc in the, 
 277. 
 
 Burning spring near Wigan, 6. 
 
 Caking coal, 52. 
 
 Candles, production of gas during 
 the burning of, 26. 
 
 Cannel coal, superiority of, for 
 producing gas, 53. 
 
 Capital requisite for works, 81. 
 
 Carbon, fixed and volatile, 53. 
 
 Carbonisation, process of, 62. 
 
 Carbonic acid, chemical com- 
 position of, and Dr. Henry’s 
 experiments on, 45. 
 
 Carbonic oxide, description and 
 mode of preparing, 42. 
 
 Carburetted hydrogen, its chemi- 
 cal equivalent and composition, 
 39. 
 
 Cement used for clay retorts, 106; 
 for iron pipes, &c., 108. 
 
 Charge, method of drawing the, 
 70 ; method, in small works, of 
 drawing and renewing the, 72. 
 
 Charges for retorts, 71. 
 
 Charging retorts, mode of, 70 ; 
 method of, in small works ; use 
 of the scoop — general descrip- 
 tion of the process, 71. 
 
 Chemistry of gas-lighting, 26. 
 
 Cherry coal, cannel coal, 52. 
 
 Chimneys of retort-houses, price 
 of building, 90. 
 
 Chlorine, condensation of gas by, 
 273. 
 
 Church and Mann’s photometer, 
 277. 
 
 Clay retorts first proposed by Mr. 
 Grafton, 100. 
 
 Clay retorts, advantages of, 98 ; 
 first used in Scotland, 101 ; first 
 used in London extensively, 
 102 ; forms of, very variable, 
 104; cost of settings of, 114; 
 duration of, 115; engraving of 
 mouth-piece of, 106; engraving 
 showing how separate lengths 
 of them are put together, 107 ; 
 their alleged p< r osity, 101; 
 where used, exhausted neces- 
 sary, 103. 
 
 Clay and iron retorts combined, 
 119; compared, 103. 
 
 Clayton, Dr., experiments of, on 
 distillation of coal, 8. 
 
 Clegg, Mr., subject of gas-lighting 
 taken up by, 14; his various 
 important inventions, 20 ; de- 
 scription of the revolving web 
 retort by, 93 ; invented the first 
 gas meter, 216; examples and 
 estimates of retort-houses by, 
 85 ; his examples and estimates 
 of cost for gas-holders, 195; his 
 recommendation relative to lay- 
 ing mains, 236 ; his estimate for 
 retort-house, 85 ; his experi- 
 ments on hydrocarbon gas, 305. 
 
 Coals, used in gas-making, 49 ; 
 supposed origin of, 50 ; first 
 mines opened in Newcastle, 50; 
 first patent obtained in con- 
 junction with, 51 ; Dr. Thom- 
 son’s classification of, 51 ; cak- 
 ing, splint, cherry, cannel, 
 anthracite, 52 ; constituents 
 of, 53 ; percentage of volatile 
 matter in certain classes, 54 ; 
 quantity of gas produced from, 
 55 ; yield of coke from, 55 ; 
 experiments of the quantity of 
 gas derived from, 57 ; residual 
 products from the .distillation, 
 294. 
 
 Coke drawn from the retorts, dis- 
 posal of the, 71. 
 
 Coke, use of red-hot, for charging 
 furnaces, 68. 
 
 Coke vault, 82. 
 
 Composition of gas, 39. 
 
 Condensation, injurious effects of 
 excess of, 145. 
 
 Condenser, various kinds in use; 
 Malam’ s condenser, 142; the ver- 
 tical, 143; description of engrav- 
 ings showing a vertical, 143 ; 
 longitudinal section and cross 
 section of, 1 44; description of con- 
 denser at Imperial Gas-Works, 
 144 ; engraving and descrip- 
 tions of tanks used to receive 
 condensed products from the, 
 147 ; Messrs. Croll and Bar- 
 low’s estimates for, 146. 
 
INDEX. 
 
 3131 
 
 Cotton-mills and factories in Lan- 
 cashire lighted by Mr. Clegg, 15. 
 
 Counterbalance, method of deter- 
 mining the weight of, for gas- 
 holder, 194. 
 
 Cowley & Co., the wrought-iron 
 main made by them for the 
 Phoenix Company, 129. 
 
 ^Jroll, Mr., his patent process of 
 purification, 129; his fire-bars, 
 and construction of furnace, 
 110 ; clay retorts used by him, 
 101 ; his mode of setting clay 
 and iron retorts, 124; his esti- 
 mate for a retort-house, 86 ; his 
 estimate for condensers, 146; 
 his process for separating am- 
 monia, 170 ; his process of 
 purifying, advantages in, 170; 
 his process — plans, section, and 
 description of the apparatus 
 used in, 171, 172; his remarks 
 on the fertilising value of re- 
 fuse lime, 173 ; his estimates of 
 the cost of purification by lime, 
 166 ; his estimate of leakage 
 in mains, 249 ; his process of 
 purification with neutral salts, 
 174. 
 
 Croll & Richards’ dry meter, 231. 
 
 Ctesias, writings of, 4. 
 
 Cyanogen, 49. 
 
 Daniell, Professor, attempts by 
 him to make gas from resin, 24. 
 
 Decomposition, gas produced by, 1. 
 
 Defines’ dry meter, 230. 
 
 Denman (Lord), judgment in the 
 case of the Queen v. Cambridge 
 Gas-Light Company, 325. 
 
 Dip-pipe, description of, 62. 
 
 Distillation of coal, Dr* Clayton’s 
 experiments on, 8 ; Dr. Hales’s 
 experiments on, 6, 62. 
 
 Division of rateable value amongst 
 the parishes in rating cases, 
 327. 
 
 Drying gas, mode of, 272. 
 
 Dry-lime purifiers, 157 ; engrav- 
 ings of, 158, 159. 
 
 Ecbatana, fountain of naphtha 
 in, 5. 
 
 Engine, gas, 215. 
 
 Estimated quantities of brick- 
 work and stone in tank of gas- 
 holder, 187. 
 
 Estimates for erecting and re- 
 newing retorts, 114; by Mr. 
 Cleggfor erecting retort-houses, 
 85 ; by Mr. Barlow for largo 
 retort-house, 85 ; by Mr. Croll 
 for a retort-house, 86 ; of cost 
 for gasholders, by Mr. Clegg, 
 195. 
 
 Exhauster, employment of an, 
 212 ; Mr. Grafton’s experi- 
 ments on, 213; Beale’s, 214; 
 Jones’s, 214; Methvin’s, 214; 
 Anderson’s, 214. 
 
 Experiments on explosions of 
 gas, 300 ; on evaporation of 
 hydrocarbon liquds, 292 ; 
 Mr. Grafton’s, on exhauster, 
 213. 
 
 Faraday’s “ Chemical Manipula- 
 tion,” table extracted from, 
 270. 
 
 Fire-bars and grate, dimensions 
 of, 111. 
 
 Fitter, gas, business of the, 25. 
 
 Flames, burning, venerated by 
 the ancient world, 2. 
 
 Flow of gas through pipes, table 
 from the “ Journal of Gas- 
 lighting,” 238. 
 
 Fuel required for carbonising 
 coal, 68. 
 
 Furnace, woodcut and descrip- 
 tion of, 110. 
 
 Gas, the constituents of, 39 ; effects 
 of temperature and pressure on, 
 261 ; moisture in, 263 ; mode 
 of burning, 286 ; explosions 
 of, 297 ; air intermixed with, 
 loss of light by, 215, 286 ; 
 weighing, 264 ; vapours inter- 
 mixed with, 270 ; consumption 
 of average per head of popula- 
 tion, 81; engine, 215; conden- 
 sation of, 244. 
 
 Gas company, first established 
 19. 
 
 Gasholder described, 179; trus- 
 
332 
 
 INDEX. 
 
 sing for, 191; examples of price 
 of, 195; specifications of, 196, 
 198 ; specifications of Pancras 
 Station, 200 ; mode of ascer- 
 taining its pressure and deter- 
 mining the counterbalancing 
 weight, 194; at Imperial Com- 
 pany’s station, Hackney, 205 ; 
 early forms of, 211 ; engraving 
 of single-lift, 192; telescopic, 
 203; tanks of, 180; description 
 of iron tanks for, 180 ; descrip- 
 tion of brick tanks for, 183. 
 
 Gillard’s water and platinum gas, 
 307. 
 
 Glance coal, or anthracite, 53. 
 
 Gordon, David, his patent for 
 compressing gas, 23. 
 
 Governor, its advantages, 257 ; 
 description of the various parts 
 of the, 257 ; engraving of, 258 ; 
 necessity of, in gas-works, 259 ; 
 used on street mains, 259. 
 
 Governor or regulator used in 
 street lamps, 260. 
 
 Grafton, Mr., clay retorts pro- 
 posed by, 100; experiments by, 
 on the subject of pressure, 213. 
 
 Greek fire-altars, 3. 
 
 Hales* experiments on the distil- 
 lation of coal, 6. 
 
 Henry, Dr., subject of gas-light- 
 ing taken up by, 10; his de- 
 cription of Mr. Murdoch’s first 
 trials, 10. 
 
 Hydraulic main, use of, described, 
 129; section and elevation of, 
 130, 131 ; cost of, usual forms 
 of, 130; fluid contained in, re- 
 marks on, 132. 
 
 Hydraulic valve, description of 
 the, 135 ; engravings of two 
 kinds of, 135. 
 
 Hydrocarbon gas, mode of manu- 
 facturing the, 304 ; produced 
 from cannel coal and water, 
 304 ; causes of failure of, 306. 
 
 Hydrocarbon process, Mr. Clegg’s 
 observations on, 305. 
 
 Hydrogen gas, method of making ; 
 description and specific gravity 
 of, 33 ; produced by the de- 
 
 composition of water ; patents 
 for combining hydrogen gas 
 with carburotted gases, 305. 
 
 Imperial gas - works, condenser 
 used at the, 144 ; magnitude of 
 operations of, 81 ; gasholders at, 
 188, 200, 205. 
 
 India-rubber rings for joints of 
 gas-pipes, 236. 
 
 Indicator pressure, 254 ; record- 
 ing, various contrivances for, 
 253. 
 
 Inflammable gas known at a very 
 early period, 1. 
 
 Inflammable gas issuing from the 
 earth, modern examples of, 6. 
 
 Inflammable gas from a coal- 
 mine, Sir James Lowther’s 
 account of, 7. 
 
 Iron retorts, useful only in small 
 works, 99 ; average production 
 from, 98; mode of setting, 117; 
 comparison of clay and, 98. 
 
 Iron-cement, recipes for making, 
 108. 
 
 Ironwork in gas-works, specifica- 
 tion of, 198. 
 
 Laming, his process of purifica- 
 tion, 175. 
 
 Lamps and candles, production of 
 gas during the burning of, 26. 
 
 Leakage of mains, 249; Mr. 
 Croll’s estimate of, 249. 
 
 Lee, Mr., estimate of rateable 
 value for Phoenix gas-works 
 by, 318. 
 
 Lime, quantity of, used for puri- 
 fication ; lime best adapted for 
 purification; varieties of lime, 
 164. 
 
 Limestones, classification of, 164. 
 
 Lowe, Mr., his successful opposi- 
 tion to oil gas, 23 ; his inven- 
 tion of carburising gases, 291; 
 his combination of clay and iron 
 retorts, 119; his reciprocating 
 retort, 93 ; his bladder valve, 
 139. 
 
 Lowther, Sir James, account by 
 him of inflammable gas from a 
 coal mine near Whitehaven, 6. 
 
ind ex. 
 
 333 
 
 Luting the retort-lids, composition 
 for, 96. 
 
 Mains described, 233 ; delivery of 
 gas from, table of, 238 ; endos- 
 mose and exosmose action on, 
 234 ; first laid by New River 
 Company, 233 ; mode of detect- 
 ing obstructions in, 245; method 
 of preserving, 244; method of 
 proving, and method of making 
 joints of, 235 ; method of making 
 the joints used in Liverpool and 
 Manchester, 237 ; necessity for 
 changing when too small, 250; 
 on laying gas, 232 ; prices of, 
 table of, 247 ; use of “ Chame- 
 roy,” 233 ; use of vulcanised 
 india-rubber rings for the joints 
 of, 237. 
 
 Malam, Mr., invention of gas- 
 meter, 216 ; his improvements 
 in purifiers, 158. 
 
 Map of gas-works and district 
 to be supplied very essential ; 
 should contain the levels, 241. 
 
 Mastic d’Aquin or iron cement 
 used by the French, 108. 
 
 Meter, early history of the, 216 ; 
 Clegg’s, 216 ; Malam’ s, 216 ; Sir 
 W. Congreve’s, 217; descrip- 
 tion of wet, 220 ; engravings of 
 wet, 220, 221, 222, 225 ; engrav- 
 ings of Wright’s station, 228 ; 
 description of dry, 230 ; Defries’ 
 dry meter, 230 ; Croll and 
 Richards’ ditto, 230 ; contin- 
 gencies in measurement of, 224 ; 
 compensating, 226; Sanders and 
 Donovan’s, 227 ; formerly used 
 as a motive power, 215. 
 
 Metropolis, progress of gas-light- 
 ing in the, 21. 
 
 Moisture, correction for, 270 ; 
 examples of correction for, 270. 
 
 Mouth-pieces for retorts, engrav- 
 ings of, 94, 95, &c. 
 
 Mouth-pieces of clay retorts, 106. 
 
 Mouth-pieces and mode of attach- 
 ment, engraving of, 96. 
 
 Murdoch’s experiments and appli- 
 cation of coal gas to useful 
 purposes, 10 ; his experiments 
 
 described in the et Philosophical 
 Transactions,” 13 ; his compari- 
 son of the comparative cost of 
 lighting by gas and by candles, 
 13; experiments on the best 
 form of retort, 91. 
 
 Nitrogen, 34. 
 
 Neutral salts, purification by, 174. 
 
 Oil, proposals to make gas from it 
 and other materials, 22; com- 
 parison of coal gas with that 
 made from, 23. 
 
 Olefiant gas, 40. 
 
 Ornamental illumination, first, 11. 
 
 Ovens, arrangement of retorts in, 
 109; retorts set in, 109. 
 
 Oxide of iron purification, 167 ; 
 spontaneous revivification, 167 ; 
 method of working, 168. 
 
 Oxygen, 32. 
 
 Pall Mall the first street lighted 
 by gas, 18. 
 
 Parochial Assessment Act, 319. 
 
 Phoenix gas-works, hydraulic 
 main at, 129. 
 
 Photometer test, value of the, 
 275. 
 
 Photometer, by Professor Bunsen, 
 276 ; engravings of the Bunsen, 
 277, 278; Romford’s, 276; 
 
 Church and Mann’s, 277. 
 
 Plan and elevation of works, 78, 
 79. ^ 
 
 Planning works, 77. 
 
 Plutarch’s notices of perpetual 
 fires, 3 ; description of the burn- 
 ing fountain in Ecbatana, 5. 
 
 Portable gas and gas-tubes first 
 used by Mr. Murdoch, 10. 
 
 Portable vessels, Gordon’s patent 
 for compressing gas into, 23. 
 
 Pressure of the gas-holder, how 
 adjusted, 195 ; barometric in- 
 fluence on gas, 262. 
 
 Pressure of gas-holders, method 
 of calculating, 194. 
 
 Pressure, remarks on regulation 
 of, 259 ; variations of, during 
 different hours of day and night, 
 256; corrections for barometric, 
 
334 
 
 INDEX. 
 
 263 ; corrections for pressure 
 and temperature easily calcu- 
 lated by Mr. Wright’s table, 
 
 264 ; necessary for district, 245 ; 
 results of excessive, 245. 
 
 Pressure-gauge, apparatus for re- 
 cording pressure, 252. 
 
 Pressure-indicators, 254. 
 
 Prices at present charged for gas, 
 24. 
 
 Profits, argument as to rating on, 
 312. 
 
 Profits of large joint-stock com- 
 panies, mode of arriving at, 313. 
 
 Purification by means of lime in 
 separate purifiers first adopted, 
 15. 
 
 Purification, earliest modes of, 
 169 ; Mr. Croll’s process of 
 separating ammonia, 170 ; plan, 
 section, and description of the 
 vessels used for, in Mr. Croll’s 
 process, 171, 172; Mr. Oroll’s 
 process by means of neutral 
 salts, 174; Mr. Laming’ s process, 
 175. The Rev. Mr. Bowditch’s 
 process, 177 ; gradual improve- 
 ments in, 141 ; division of pro- 
 cess, 141 ; notice of the ap- 
 paratus used for, 141 ; by means 
 of the washer, 149 ; by means 
 of the scrubber, 152 ; by means 
 of oxide of iron, 167 ; expense of, 
 by Mr. Croll and Mr. Barlow, 
 166 ; by wet lime, 153. 
 
 Purifiers, Mr. Croll’s opinion as 
 to dry lime, 173; wet lime, 155; 
 dry lime, construction of, &c., 
 
 157. Plan and section of dry 
 lime, showing hydraulic valve, 
 inlet and outlet pipes, 160, 161 ; 
 mode of working the, 162; 
 method of working, and charg- 
 ing them with lime, 163 ; method 
 of determining the size required, 
 
 158. Wet lime, 153 ; mode of 
 working, and quantity of lime 
 required, 166. 
 
 Purifying process, order in which 
 the various part3 succeed each 
 other, 140. 
 
 Pyrometer, objections to Wedg- 
 wood’s ; Darnell’ s, 64. 
 
 Radiation of heat from surfaces 
 in air and in water, table show- 
 ing quantity of heat lost by, 
 145. 
 
 Rateable value, Mr. Lee’s esti- 
 mate, 318; estimate by Mr. 
 Penfold, 317 ; estimate by the 
 Author, 322. 
 
 Rating of gas-works, general 
 principles, 309; objections to 
 present mode, 310 ; law of, as 
 laid down in the Parochial 
 Assessment Act, 311. 
 
 Receivers or syphons in gas mains, 
 243. 
 
 Repairs and restorations, allow- 
 ance for, in rating cases, 315. 
 
 Resin and other materials, pro- 
 posals to make gas from, 22. 
 
 Resin, Professor Daniell’ s attempts 
 to make gas from, 24. 
 
 Retort-house, usual form of, 82-, 
 thickness of walls in ; allowance 
 for retorts undergoing repair, 
 84; cost of erecting, examples 
 and estimates by Mr. Clegg, 
 85 ; estimates for, by Mr. Croll 
 and Mr. Barlow, 85. 
 
 Retorts, Murdoch’s experiments 
 on the form of, 14, 91; used in 
 gas-making, 91 ; Brunton’s de- 
 scription of, 92 ; Lowe’s reci- 
 procating, 93 ; Clegg’s revolving 
 web, 93 ; mode of setting iron, 
 116 ; mode of setting clay, 111 ; 
 made of fire-clay, proposed by 
 Mr. Grafton, 100 ; of clay at Im- 
 perial Company’s works, 111; 
 of clay in Scotland, 101 ; of clay 
 first used in London on an ex- 
 tensive scale by Mr. Croll, 101 ; 
 cement used for jointing clay, 
 106 ; consumption of fuel for 
 heating, 68 ; comparison of clay 
 andiron, 104; alleged porosity 
 of clay, 103 ; comparative wear 
 and tear of, 98 ; encrustation of 
 carbon in, 73 ; method of clean- 
 ing, 73; Clift’s brick, 101; of 
 clay and iron combination, 
 elevation of those erected by 
 Mr. Croll, 126, 127, &c. ; of clay 
 and iron require different in- 
 
INDEX. 
 
 335 
 
 tensities of heat, 121 ; method of 
 charging them in small works ; 
 general description of the pro- 
 cess of charging, 70 ; number 
 of men required for work- 
 ing, 70 ; method of drawing 
 the charge from, 70 ; method 
 of drawing and renewing the 
 charges in small works, 72; 
 temperatures most advisable for 
 working iron and clay, 67 ; 
 necessity for reducing the pres- 
 sure of gas in the, 73; settings 
 of, diversity of opinion, 114; 
 price of settings, 114; of iron, 
 only useful in small works, 116. 
 
 Scoop for charging, use of the, 
 71. 
 
 Scotch gas-works, clay retorts, 
 104. 
 
 Scrubber or coke condenser, 1527 
 
 Shadows, comparison of gases by 
 means of, 27 5. 
 
 Shirley, his Paper in the “ Philo- 
 sophical Transactions,” 8. 
 
 Site for gas-works, choice of a, 74 ; 
 near a railway, canal, or navi- 
 gable river, very favourable, 75. 
 
 South Metropolitan works, trials 
 made of the hydrocarbon pro- 
 cess, 306. 
 
 Specific gravity of gas, mode of 
 ascertaining, 265; Mr. Wright’s 
 apparatus for taking, 265. 
 
 Specification of gas-holder, single 
 lift, 196; of gas-holder and iron 
 tank, 205 ; of gas-holder of 
 Imperial Company, 200 ; of iron 
 work for gas-works, 198 ; of 
 brick tanks, 186, 188 ; of iron 
 tank, 180. 
 
 Spedding’s proposal to apply 
 natural gas for lighting White- 
 haven, 7. 
 
 Splint coal, 52. 
 
 Station, division of rateable value 
 where gas-works have more 
 than one manufacturing, 329. 
 
 Station meter, description and 
 engraving of, 227. 
 
 Statutable allowances in rating 
 gas-works, 315. 
 
 Sulphuret of carbon, difficulty 
 of separating it from coal gas, 
 48. 
 
 Sulphuretted hydrogen, descrip- 
 tion and tests for discovering, 
 43, 282. 
 
 Sulphate of ammonia, how made, 
 296. 
 
 Tank for receiving products of 
 condensation ; description of, 
 147 ; connection between the 
 hydraulic main and the, 147 ; 
 method of removing liquids from 
 the, 147. 
 
 Tanks of gas-holders described, 
 178; cast-iron, 180; specifica- 
 tion of, 181, 205 ; annular, 183 ; 
 brick and masonry, 183; speci- 
 fication of, 186, 188. 
 
 Tar, price of, 149. 
 
 Tar used as fuel, 69. 
 
 Telescopic gas-holders, 203 ; de- 
 scription of, and engraving 
 showing water-seal, 204 ; at 
 Imperial Company’s station, 
 Hackney, 205. 
 
 Temperature and long-continued 
 distillation, effects of, 48. 
 
 Temperature of furnaces corre- 
 sponding with colours, 65. 
 
 Temperature of gas, correction 
 for, 261. 
 
 Temperature, injurious effects of 
 low, 67 ; formula for correcting 
 the volume of the gas according 
 to, 267.. 
 
 Testing with bromine and chlorin e, 
 mode of, 273. 
 
 Tests for the various impurities 
 contained in coal gas, 282. 
 
 Thomson, Dr., his divisions of 
 coal, 51. 
 
 Yalve, the hydraulic, 135 : en- 
 gravings and description of 
 two kinds of, 135 ; slide, de- 
 scription and engravings of, 
 
 i38. 
 
 Veneration of the ancient world 
 for burning flames, 2, 
 
 Vitruvius and others, writings 
 of, 4. 
 
336 
 
 INDEX. 
 
 Wash-vessel, position in which it 
 is placed, 149; plan of a, 149; 
 side elevation and description 
 of, 150 ; front elevation of, 151. 
 
 Water gas, 304. 
 
 Watson, Dr., discoveries of, 9. 
 
 Wedgwood’s pyrometer, 64. 
 
 Weighing gas, 281. 
 
 Wet and dry lime purifiers, 153. 
 
 Wickstead’s India-rubber rings 
 for joints of pipes, 236. 
 
 Winsor, Mr., his first exhibition 
 and lectures on ga3-lighting, 
 12; patent obtained by, 15; 
 assumed the title of inventor of 
 
 gas, 16 ; his energetic efforts 
 to establish a Company, 17; 
 occupied premises in Pall Mall, 
 1 8 ; the subscribers applied to 
 Parliament, 18 ; succeeded in 
 getting incorporated the “ Gas- 
 Light and Coke Company/' 19. 
 
 Works, gas, magnitude described, 
 81 ; plan of, 78. 
 
 Wright, Mr., his apparatus for 
 detecting sulphuret of carbon 
 in coal gas, 283 ; his apparatus 
 for taking the specific gravity 
 of gas, 282 ; his table for as- 
 certaining specific gravity, 265, 
 
 THE END, 
 
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 Mr. J. Cubitt, C.E. 
 
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 MAIN DRAINAGE, METROPOLIS. 
 North Side. 
 
 Map showing Interception of Sewers. 
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 Outfall Sewer. Reservoir and Outlet. 
 
 Details. 
 
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 Humber s Modern Engineering . Fourth Series . 
 
 A RECORD of the PROGRESS of MODERN ENGINEER- 
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 NAME OF ENGINEER. 
 
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 working drawings of all the most recent and noteworthy engineering works. The 
 plates are excellently lithographed, and the present volume of the * Record ’ is not a 
 whit behind its predecessors.” — Mechanics' Magazine. 
 
 “We gladly welcome another year’s issue of this valuable publication from the able 
 pen of Mr. Humber. The accuracy and general excellence of this work are well 
 known, while its usefulness in giving the measurements and details of some of the 
 latest examples of engineering, as carried out by the most eminent men in the profes- 
 sion, cannot be too highly prized.” — Artizan. 
 
 “The volume forms a valuable companion to those which have preceded it, and 
 cannot fail to prove a most important addition to every engineering library .” — Mining 
 Journal. 
 
 “No one of Mr. Humber’s volumes was bad ; all were worth their cost, from the 
 mass of plates from well-executed drawings which they contained. In this respect, 
 perhaps, this last volume is the most valuable that the author has produced.” — Prac- 
 tical Mechanics' Journal. 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 5 
 
 Humber's Great Work on Bridge Construction. 
 
 A COMPLETE and PRACTICAL TREATISE on CAST and 
 WROU GHT-IRON BRIDGE CONSTRUCTION, including 
 Iron Foundations. In Three Parts — Theoretical, Practical, and 
 Descriptive. By William Humber, Assoc. Inst. C.E., and M. Inst. 
 M.E. Third Edition, revised and much improved, with 1 1 5 Double 
 Plates (20 of which now first appear in this edition), and numerous 
 additions to the Text. In 2 vols. imp. 4to., price 6/. 1 6s. 6d. half- 
 bound in morocco. [Recently published. 
 
 “ A very valuable contribution to the standard literature of civil engineering. In 
 addition to elevations, plans, and sections, large scale details are given, which very 
 much enhance the instructive worth of these illustrations. No engimee'r would wil- 
 lingly be without so valuable a fund of information. ” — Civil Engineer and A rchitect' s 
 Journal. 
 
 “The First or Theoretical Part contains mathematical investigations of the prin- 
 ciples involved in the various forms now adopted in bridge construction. These 
 investigations are exceedingly complete, having evidently been very carefully con- 
 sidered and worked out to the utmost extent that can be desired by the practical man. 
 The tables are of a very useful character, containing the results of the most recent 
 experiments, and amongst them are some valuable tables of the weight and cost of 
 cast and wrought-iron structures^actually erected. The volume of text is amply illus- 
 trated by numerous woodcuts, plates, and diagrams : and the plates in the second 
 volume do great credit to both draughtsmen and engravers. In conclusion, we have 
 great pleasure in cordially recommending this work to our readers.” — Artizan. 
 
 u Mr. Humber’s stately volumes lately issued— in which the most important bridges 
 erected during the last five years, under the direction of the late Mr. Brunei, Sir W. 
 Cubitt, Mr. Hawkshaw, Mr. Page, Mr. Fowler, Mr. Hemans, and others among our 
 most eminent engineers, are drawn and specified in great detail.” — Engineer. 
 
 Weale's Engineer s Pocket-Book. 
 
 THE ENGINEER’S, ARCHITECT’S, and CONTRACTOR’S 
 POCKET-BOOK (Lockwood & Co.’s; formerly Weale’s). 
 Published Annually. In roan tuck, gilt edges, with 10 Copper- 
 Plates and numerous Woodcuts. Price 6s. 
 
 “ A vast amount of really valuable matter condensed into the small dimen- 
 sions of a book which is, in reality, what it professes to be — a pocket-book 
 
 We cordially recommend the book to the notice of the managers of coal and other 
 mines; to them it wil‘l prove a handy book of reference on a variety of subjects more 
 or less intimately connected with their profession. It might also be placed with 
 advantage in the hands of the subordinate officers in collieries.” — Colliery Gtiardian , 
 
 ** The assignment of the late Mr. Weale’s 'Engineers Pocket-Book' to Messrs. 
 Lockwood & Co. has by no means lowered the standard value of the work. It is too 
 well known among those for whom it is specially intended, to need more from us than 
 the observation that this continuation of Mr. Weale’s series of Pocket Books well 
 sustains the reputation the work has so long enjoyed. Every branch of engineering 
 is treated of, and facts, figures, and data of every kind abound.” — Mechanics' Mag. 
 
 “ It contaips a large amount of information peculiarly valuable to those for whose 
 use it is compiled. We cordially commend it to the engineering and architectural 
 professions generally.” — Minmg Journal. 
 
 Iron Bridges , Girders , Roofs , &c. 
 
 THE APPLICATION OF IRON TO THE CONSTRUC- 
 TION OF BRIDGES, GIRDERS, ROOFS, and other W orks. 
 By Francis Campin, C.E. With numerous Illustrations. i2mo, 
 cloth boards, 3J. [Just published. 
 
6 
 
 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 Barlow on the Strength of Materials , enlarged. 
 
 A TREATISE ON THE STRENGTH OF MATERIALS, 
 with Rules for application in Architecture, the Construction of 
 Suspension Bridges, Railways, &c. ; and an Appendix on the 
 Power of Locomotive Engines, and the effect of Inclined Planes 
 and gradients. By Peter Barlow, F.R. S., Mem. Inst, of France ; 
 of the Imp. and Royal Academies of St. Petersburgli and Brussels ; 
 of the Amer. Soc. Arts ; and Hon. Mem. Inst. Civil Engineers. 
 A New and considerably Enlarged Edition, revised by his Sons, 
 P. W. Barlow, F.R.S., Mem. Inst. C.E., and W. H. ^Barlow, 
 F.R.S., Mem. of Council Inst. C.E., to which are added a Sum- 
 mary of Experiments by Eaton Hodgiunson, F.R.S., William 
 Fairbairn, F.R.S., and David Kirkaldy ; an Essay (with 
 Illustrations) on the effect produced by passing Weights over 
 Elastic Bars, by the Rev. Robert Willis, M.A., F.R.S. And 
 Formulae for Calculating Girders, &c. The whole arranged and 
 edited by William Humber, Assoc. Inst. C.E., and Mem. Inst. 
 M.E., Author of “ A Complete and Practical Treatise on Cast and 
 Wrought-Iron Bridge Construction,” &c. &c. Demy 8vo, 400 pp., 
 with 19 large Plates, and numerous woodcuts, price i8j. cloth. 
 
 Opinions of ihe Press. 
 
 “ This edition has undergone considerable improvement, and has been brought down 
 to the present date. It is one of the first books of reference in existence.” — Artizan. 
 
 “ Although issued as the sixth edition, the volume under consideration is worthy of 
 being regarded, for all practical purposes, as an entirely new work . . . the book 
 
 is undoubtedly worthy of the highest commendation, and of an honourable place in 
 the library of every engineer.” — Mining Journal. 
 
 “An increased value has been given to this very valuable work by the addition of 
 a large amount of information, which cannot prove otherwise than highly useful to 
 
 those who require to consult it The arrangement and editing of this 
 
 mass of information has been undertaken by M-r. Humber, who has most 'ably fulfilled 
 a task requiring special care and ability to render it a success, which this edition most 
 certainly is. He has given the finishing touch to the volume by introducing into it 
 an interesting memoir of Professor Barlow, which tribute of respect, we are sure, will 
 be appreciated by the members of the engineering profession.” — Mechanics' Magazine. 
 
 “A book which no engineer of any kind can afford to be without. In its present 
 form its former value is much increased.” — Colliery Guardian. 
 
 “The best book on the subject which has yet appeared We know of 
 
 no work that so completely fulfils its mission Asa scientific work of the 
 
 first class, it deserves a foremost place on the bookshelves of every civil engineer and 
 practical mechanic.” — English Mechanic. 
 
 “ There is not a pupil in an engineering school, an apprentice in an engineer’s dr 
 architect’s office, or a competent clerk of works, who will not recognise in the scientific 
 volume newly given to circulation, an old and valued friend. . . So far as the strength 
 of timber is concerned, there is no greater authority than Barlow.” — Building News. 
 
 “ It is scarcely necessary for us to make any comment upon the first portion of 
 
 the new volume Valuable alike to the student, tyro, and experienced 
 
 practitioner, it will always rank in future, as it has hitherto done, as the standard 
 treatise upon this particular subject.” — Engineer. 
 
 “The present edition offers some important advantages over previous ones. The 
 additions are both extensive and valuable, comprising experiments by Hodgkinson on 
 the strength of cast-iron ; extracts from papers on the transverse strength of beams by 
 W. H. Barlow ; an article on the strength of columns ; experiments by Fairbairn, on 
 iron and steel plates, on the behaviour of girders subjected to the vibration of a 
 changing load, and on various cast and wrought-iron beams ; experiments by Kirkaldy, 
 on wrought-iron and steel bars, and a short appendix of formulae for ready application 
 in computing the strains on bridges.” — Enginecrmg. 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 7 
 
 Strains, Formula? & Diagrams for Calculation of. 
 
 A HANDY BOOK for the CALCULATION of STRAINS 
 in GIRDERS and SIMILAR STRUCTURES, and their 
 STRENGTH ; consisting of Formulae and Corresponding Diagrams, 
 with numerous Details for Practical Application, &c. By William 
 Humber, Assoc. Inst. C. E., &c. Fcap. 8vo, with nearly ioo 
 Woodcuts and 3 Plates, price 7 s. 6 d. cloth. 
 
 “To supply a universally recognised want of simple formulae, applicable to the 
 varied problems to be met with in ordinary practice, Mr. Humber, whose works on 
 modern engineering afford sufficient evidence of his qualifications for the task, has 
 compiled his ‘Handy Book.’ The arrangement of the matter in this little volume is 
 
 as convenient as it well could be The system of employing diagrams as a 
 
 substitute for complex computations is one justly coming into great favour, and in that 
 respect Mr. Humber’s volume is fully up to the times.” — Engineering. 
 
 “ The formulae are neatly expressed, and the diagrams good.” — Athenceum. 
 
 “ That a necessity existed for the book is evident, we think ; that Mr. Humber has 
 
 achieved his design is equally evident We heartily commend the really handy 
 
 book to our engineer and architect readers.” — English Mechanic . 
 
 Strains. 
 
 THE STRAINS ON STRUCTURES OF IRONWORK ; 
 with Practical Remarks 011 Iron Construction. By F. W. Sheilds, 
 M. Inst. C.E. Second Edition, with 5 plates. Royal 8vo, 5>r. cloth. 
 Contents . — Introductory Remarks ; Beams Loaded at Centre ; Beams Loaded at 
 unequal distances between supports ; Beams uniformly Loaded ; Girders with triangu- 
 lar bracing Loaded at centre ; Ditto, Loaded at unequal distances between supports ; 
 Ditto, uniformly Loaded ; Calculation of the Strains on Girders with triangular 
 Basings ; Cantilevers; Continuous Girders; Lattice Girders; Girders with Vertical 
 Struts and Diagonal Ties ; Calculation of the Strains on Ditto ; Bqw and String 
 Girders ; Girders of a form not belonging to any regular figure ; Plate Girders ; Ap- 
 portionments of Material to Strain ; Comparison of different Girders ; Proportion of 
 Length to Depth of Girders ; Character of the Work ; Iron Roofs. 
 
 Construction of Iron Beams, Pillars, &c. 
 
 IRON AND HEAT, Exhibiting the Principles concerned in the 
 Construction of Iron Beams, Pillars, and Bridge Girders, and the 
 Action of Heat in the Smelting Furnace. By James Armour, 
 C.E. Woodcuts, i2mo, cloth boards, 3 s. 6 d. ; cloth limp, 2 s. 6 d. 
 
 [Just published. 
 
 Power in Motion. 
 
 POWER IN MOTION : Horse Power, Motion, Toothed Wheel 
 Gearing, Long and Short Driving Bands, Angular Forces, &c. 
 By James Armour, C.E. With 73 Diagrams. i2mo, cloth 
 boards, 3 s. 6 d. [ This day. 
 
 Trigonometrical Surveying. 
 
 AN OUTLINE OF TPIE METHOD OF CONDUCTING A 
 TRIGONOMETRICAL SURVEY, for the Formation of Geo- 
 graphical and Topographical Maps and Plans, Military Recon- 
 naissance, Levelling, &c., with the most useful Problems in Geodesy 
 and Practical Astronomy, and Formulae and Tables for Facilitating 
 their Calculation. By Major-General Frome, R.E., Inspector- 
 General of Fortifications, &c. Third Edition, revised and improved. 
 With 10 Plates and 113 Woodcuts. Royal 8vo, 12s. cloth. 
 
8 
 
 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 Hydraulics. 
 
 HYDRAULIC TABLES, CO-EFFICIENTS, and FORMULAE 
 for finding the Discharge of Water from Orifices, Notches, Weirs, 
 Pipes, and Rivers. By John Neville, Civil Engineer, M.R.I.A. 
 Second Edition, with extensive Additions, New Formulae, Tables, 
 and General Information on Rain-fall, Catchment-Basins, Drainage, 
 Sewerage, Water Supply for Towns and Mill Power. With nume- 
 rous Woodcuts, 8vo, i6j\ cloth. 
 
 * ** This work contains a vast number of different hydraulic 
 formulae, and the most extensive and accurate tables yet published 
 for finding the mean velocity of discharge from triangular, quadri- 
 lateral, and circular orifices, pipes, and rivers ; with experimental 
 results and co-efficients ; effects of friction ; of the velocity of 
 approach ; and of curves, bends, contractions, and expansions ; the 
 best form of channel ; the drainage effects of long and short weirs, 
 and weir-basins ; extent of back-water from weirs ; contracted 
 channels ; catchment-basins ; hydrostatic and hydraulic pressure ; 
 water-power, &c. &c. 
 
 Levelling. 
 
 A TREATISE on the PRINCIPLES and PRACTICE of 
 LEVELLING ; showing its Application to Purposes of Railway 
 and Civil Engineering, in the Construction of Roads ; with Mr. 
 Telford’s Rules for the same. By Frederick W. Simms, 
 F.G.S., M. Inst. C.E. Fifth Edition, very carefully revised, with 
 the addition of Mr. Law’s Practical Examples for Setting out 
 Railway Curves, and Mr. Traut wine’s Field Practice of Laying 
 out Circular Curves. With 7 Plates and numerous Woodcuts. 8vo, 
 8s. 6d. cloth. *** Trautwine on Curves, separate, price 5.5-. 
 
 “One of the most important text-books for the general surveyor, and there is 
 scarcely a question connected with levelling for which a solution would be sought but 
 that would be satisfactorily answered by consulting the volume.” — Mining Journal. 
 
 “ The text-book on levelling in most of our engineering schools and colleges.” — 
 Engineer. 
 
 “The publishers have rendered a substantial service to the profession, especially to 
 the younger members, by bringing out the present edition of Mr. Simms’s useful work.” 
 — E ngineering. 
 
 Tunnelling. 
 
 PRACTICAL TUNNELLING ; explaining in Detail the Setting 
 out of the Works ; Shaft Sinking and Heading Driving ; Ranging 
 the Lines and Levelling Under-Ground ; Sub-Excavating, Timber- 
 ing, and the construction of the Brickwork of Tunnels ; with the 
 Amount of Labour required for, and the Cost of the various Por- 
 tions of the Work. By Fredk. W. Simms, F. R. A. S., F. G.S., 
 M. Inst. C.E., Author of “A Treatise on the Principles and 
 Practice of Levelling,” &c. &c. Second Edition, revised by W. 
 Davis Haskoll, Civil Engineer, Author of “The Engineer’s 
 Field-Book,” &c. &c. With 16 large folding Plates and numerous 
 Woodcuts. Imperial 8vo, 1 l. is. cloth. 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 9 
 
 Strength of Cast Iron , &c. 
 
 A PRACTICAL ESSAY on the STRENGTH of CAST IRON 
 and OTHER METALS ; intended for the Assistance of Engineers, 
 Iron-Masters, Millwrights, Architects, Founders, Smiths, and 
 others engaged in the Construction of Machines, Buildings, &c. ; 
 containing Practical Rules, Tables, and Examples, founded on a 
 series of New Experiments ; with an Extensive Table of the Pro- 
 perties of Materials. By the late Thomas Tredgold, Mem. Inst. 
 C.E., Author of “ Elementary Principles of Carpentry,” “ History 
 of the Steam-Engine,” &c. Fifth Edition, much improved. 
 Edited by Eaton Hodgkinson, F.R.S. ; to which are added 
 EXPERIMENTAL RESEARCHES on the STRENGTH and 
 OTHER PROPERTIES of CAST IRON ; with the Develop- 
 ment of New Principles, Calculations Deduced from them, and 
 Inquiries Applicable to Rigid and Tenacious Bodies generally. By 
 the Editor. The whole Illustrated with 9 Engravings and nume- 
 rous Woodcuts. 8vo, 1 2s. cloth. 
 
 *** Hodgkinson’s Experimental Researches on the 
 Strength and Other Properties of Cast Iron may be had 
 separately. With Engravings and Woodcuts. 8vo, price 6s. cloth. 
 
 The Iligh-Pressu re Steam Engine. 
 
 THE HIGH-PRESSURE STEAM ENGINE ; an Exposition 
 of its Comparative Merits, and an Essay towards an Improved 
 System of Construction, adapted especially to secure Safety and 
 Economy. By Dr. Ernst Alban, Practical Machine Maker, 
 Plau, Mecklenberg. Translated from the German, with Notes, by 
 Dr. Pole, F.R.S., M. Inst. C.E., &c. &c. With 28 fine Plates, 
 8vo, 1 6s. 6d. cloth. 
 
 “ A work like this, which goes thoroughly into the examination of the high-pressure 
 engine, the. boiler, and its appendages, &c., is exceedingly useful, and deserves a place 
 in every scientific library.” — Steam Shipping Chronicle. 
 
 Tables of Curves. 
 
 TABLES OF TANGENTIAL ANGLES and MULTIPLES 
 for setting out Curves from 5 to 200 Radius. By Alexander 
 Beazeley, M. Inst. C.E. Printed on 48 Cards, and sold in a 
 cloth box, waistcoat-pocket size, price 3s. 6d. 
 
 “ Each table is printed on a small cafd, which, being placed on the theodolite, leaves 
 the hands free to manipulate the instrument — no small advantage as regards the rapidity 
 of work. They are clearly printed, and compactly fitted into a small case for the 
 pocket — an arrangement that will recommend them to all practical men.” — Engineer. 
 
 “ Very handy : a man may know that all his day’s work must fall on two of these 
 cards, which he puts into his own card-case, and leaves the rest behind.” — Athenceum. 
 
 Laying Out Curves . 
 
 THE FIELD PRACTICE of LAYING OUT CIRCULAR 
 CURVES for RAILROADS. By John C. Trautwine, C.E., 
 of the United States (extracted from Simms’s Work on Levelling). 
 8vo, $s. sewed. 
 
IO 
 
 WORKS PUBLISHED BV LOCKWOOD & CO. 
 
 Estimate and Pyice Book. 
 
 THE CIVIL ENGINEER’S AND CONTRACTOR’S ESTI- 
 MATE AND PRICE BOOK for Plome or Foreign Service : 
 in reference to Roads, Railways, Tramways, Docks, Harbours, 
 Forts, Fortifications, Bridges, Aqueducts, Tunnels, Sewers, Water- 
 works, Gasworks, Stations, Barracks, Warehouses, &c. &c. &c. 
 With Specifications for Permanent Way, Telegraph Materials, 
 Plant, Maintenance, and Working of a Railway ; and a Priced List 
 of Machinery, Plant, Tools, &c., required in the execution of Public 
 Works. By W. Davis Haskoll, C.E. Plates and numerous 
 Woodcuts. Published annually. Demy 8vo, cloth, 6s. 
 
 As furnishing a variety of data on every conceivable want to civil engineers and 
 contractors, this book has ever stood perhaps unrivalled .’’—Architect, Jan. 21, 1871. 
 
 “ The care with which the particulars are arranged reflects credit upon the author, 
 each subject being divided into tables under their own special heads, so that no 
 difficulty arises in finding the exact thing one wants. The value of the work to the 
 student and the experienced contractor is inestimable.” — Mechanic's Mag. , Feb. 3. 
 
 “ Mr. Haskoll has bestowed very great care upon the preparation of his estimates 
 and prices, and the work is one which appears to us to be in every way deserving of 
 confidence.”' — Builder's Weekly Reporter , Jan. 27, 1871. 
 
 Surveying ( Land and Marine). 
 
 LAND AND MARINE SURVEYING, in Reference to the 
 Preparation of Plans for Roads and Railways, Canals, Rivers, 
 Towns’ Water Supplies, Docks and Harbours ; with Description 
 and Use of Surveying Instruments. By W. Davis Haskoll, C.E., 
 Author of “The Engineer’s Field Book,” “ Examples of Bridge 
 and Viaduct Construction,” &c. Demy 8vo, price 12s. 6d. cloth, 
 with 14 folding Plates, and numerous Woodcuts. 
 
 “ * Land and Marine Surveying' is a most useful and well arranged book for the 
 
 aid of a student We can strongly recommend it as a carefully- written 
 
 and valuable text-book.” — Builder , July 14, 1868. 
 
 “ He only who is master of his subject can present it in such a way as to make it 
 intelligible to the meanest capacity. It is in this that Mr. Haskoll excels. He has 
 knowledge and experience, and can so give expression to it as to make any matter on 
 
 which he writes, clear to the youngest pupil in a surveyor’s office The 
 
 work will be found a useful one to men of experience, for there are few such who will 
 not get some good ideas from it ; but it is indispensable to the young practitioner.” — 
 Colliery Guardian , May 9, 1868. 
 
 “ A volume which cannot fail to prove of the utmost practical utility It 
 
 is one which may be safely recommended to all students who aspire to become clean 
 and expert surveyors ; and from the exhaustive manner in which Mr. Haskoll has 
 placed his long experience at the disposal of his readers, there will henceforth be no 
 excuse for the complaint that young practitioners are at a disadvantage, through the 
 neglect of their seniors to point out the importance of minute details, since they can 
 readily supply the deficiency by the study of the volume now under consideration.”— 
 Mining Journal , May 5, 1868. 
 
 Engineering Fieldwork. 
 
 THE PRACTICE OF ENGINEERING FIELDWORK, 
 applied to Land and Hydraulic, Hydrographic, and Submarine 
 Surveying and Levelling. Second Edition, revised, with consider- 
 able additions, and a Supplementary Volume on WATER- 
 WORKS, SEWERS, SEWAGE, and IRRIGATION. By W. 
 Davis Haskoll, C.E. Numerous folding Plates. Demy 8vo, 2 
 vols. in one, cloth boards, 1 /. IJ*. (published at 2/. 4J.) 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 ii 
 
 Fire Engineering, 
 
 FIRES, FIRE-ENGINES, AND FIRE BRIGADES. With 
 a History of Manual and Steam Fire-Engines, their Construc- 
 tion, Use, and Management ; Remarks on Fire-Proof Build- 
 ings, and the Preservation of Life from Fire ; Statistics of the Fire 
 Appliances in English Towns ; Foreign Fire Systems ; Hints for 
 the formation of, and Rules for, Fire Brigades ; and an Account of 
 American Steam Fire-Engines. By Charles F. T. Young, C.E., 
 Author of “ The Economy of Steam Power on Common Roads, ” 
 &c. With numerous Illustrations, Diagrams, &c., handsomely 
 printed, 544 pp., demy 8vo, price I /. 4 s, cloth. 
 
 “ A large well-filled and useful book upon a subject which possesses a wide and 
 
 increasing public interest To such of our readers as are interested in the 
 
 subject of fires and fire apparatus we can most heartily commend this book 
 
 It is really the only English work we now have upon the subject.” — Engineeruig. 
 
 “ Mr. Young has proved by his present work that he is a good engineer, and pos- 
 sessed of sufficient literary energy to produce a very readable and interesting volume.” 
 — Engineer. 
 
 “A volume which must be regarded as the text-book of its subject, and which in 
 point of interest and intrinsic value is second to no contribution to a special depart- 
 ment of history with which we are acquainted. ‘ Fires, Fire-Engines, and Fire 
 Brigades’ is the production of an earnest and diligent writer who comes to the task he 
 has undertaken with a thorough love of it, and a firm determination to do it justice. 
 
 . . . . The style of the work is admirable It has the surpassing 
 
 merit of being thoroughly reliable.” — Eistirance Record. 
 
 “Great credit is unquestionably due to Mr. Young for having brought before the 
 public the results of his exploration in this hitherto untrodden field. We strongly 
 recommend the book to the notice of all who are in any way interested in fires, fire- 
 engines, or fire-brigades.” — Mechanics’ Magazine. 
 
 Manual of Mining Tools. 
 
 MINING TOOLS. For the use of Mine Managers, Agents, 
 Mining Students, &c. By William Morgans, Lecturer on Prac- 
 tical Mining at the Bristol School of Mines. i2mo. With an 
 Atlas of Plates, containing 200 Illustrations. 4to. [ Just ready. 
 
 Earthwork , Measurement and Calculation of. 
 
 A MANUAL on EARTHWORK. By Alex. J. S. Graham, 
 C.E., Resident Engineer, Forest of Dean Central Railway. With 
 numerous Diagrams. i8mo, 2 s. 6 d. cloth. 
 
 “We can cordially recommend the work to the notice of our readers.” — Building 
 News. 
 
 “As a really handy book for reference, we know of no work equal to it ; and the 
 railway engineers and others employed in the measurement and calculation of earth- 
 work will find a great amount of practical information very admirably arranged, and 
 available for general or rough estimates, as well as for the more exact calculations 
 required in the engineers’ contractor’s offices.” — Artizan. 
 
 “ The object of this little book is an investigation of all the principles requisite for 
 the measurement and calculation of earthworks, and a consideration of the data neces- 
 sary for such operations. The author has evidently bestowed much care in effecting 
 this object, and points out with much clearness the results of his own observations, 
 derived from practical experience. The subjects treated of are accompanied by well- 
 executed diagrams and instructive examples.” — Army and Navy Gazette. 
 
12 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 Field-Book for Engineers. 
 
 THE ENGINEER’S, MINING SURVEYOR’S, * and CON- 
 TRACTOR’S FIELD-BOOK. By W. Davis Haskoll, Civil 
 Engineer. Second Edition, much enlarged, consisting of a Series 
 of Tables, with Rules, Explanations of Systems, and Use of Theo- 
 dolite for Traverse Surveying and Plotting the Work with minute 
 accuracy by means of Straight Edge and Set Square only ; Levelling 
 with the Theodolite, Casting out and Reducing Levels to Datum, 
 and Plotting Sections in the ordinary manner; Setting out Curves 
 with the Theodolite by Tangential Angles and Multiples with Right 
 and Left-hand Readings of the Instrument ; Setting out Curves 
 without Theodolite on the System of Tangential Angles by Sets of 
 Tangents and Offsets; and Earthwork Tables to 80 feet deep cal- 
 culated for every 6 inches in depth. With numerous wood-cuts, 
 i2mo, price 12 s. cloth. 
 
 “ A very useful work for the practical engineer and surveyor. Every person 
 engaged in engineering field operations will estimate the importance of such a work 
 and the amount of valuable time which will be saved by reference to a set of reliable 
 tables prepared with the accuracy and fulness of those given in this volume.” — Rail- 
 way Nezus. 
 
 “The book is very handy, and the author might have added that the separate tables 
 of sines and tangents to every minute will make it useful for many other purposes, the 
 genuine traverse tables existing all the same.” — Atkenceum. 
 
 “ The work forms a handsome pocket volume, and cannot fail, from its portability 
 and utility, to be extensively patronised by the engineering profession.” — Mining 
 Journal. 
 
 “We know of no better field-book of reference or collection of tables than that 
 Mr. Haskoll has given.” — Artizan. 
 
 “ A series of tables likely to be very useful to many civil engineers.” — Building Nezvs. 
 “A very useful book of tables for expediting field-work operations. . . . The present 
 edition has been much enlarged. ” — Mechanics' Magazine. 
 
 “We strongly recommend this second edition of Mr. Haskoll’s ‘ Field Book* to all 
 classes of surveyors.” — Colliery Guardian. 
 
 Railway Engineering. 
 
 THE PRACTICAL RAILWAY ENGINEER. A concise 
 Description of the Engineering and Mechanical Operations and 
 Structures which are combined in the Formation of Railways for 
 Public Traffic ; embracing an Account of the Principal Works exe- 
 cuted in the Construction of Railways ; with Facts, Figures, and 
 Data, intended to assist the Civil Engineer in designing and executing 
 the important details required. By G. Drysdale Dempsey, C.E. 
 Fourth Edition, revised and greatly extended. With 71 double 
 quarto Plates, 72 Woodcuts, and Portrait of George Stephenson. 
 One large vol. 4to, 2/. I2J-. 6 d. cloth. 
 
 Harbours. 
 
 THE DESIGN and CONSTRUCTION of HARBOURS. By 
 Thomas Stevenson, F.R.S.E., M.I.C.E. Reprinted and en- 
 larged from the Article “Harbours,” in the Eighth Edition of “ The 
 Encyclopaedia Britannica.” With 10 Plates and numerous Cuts. 
 8vo, ioj*. 6 d. cloth. 
 
WORKS PUBLISHED BV LOCKWOOD & CO. 
 
 13 
 
 Bridge Construction in Masonry , Timber, and 
 
 Iron. 
 
 EXAMPLES OF BRIDGE AND VIADUCT CONSTRUC- 
 TION OF MASONRY, TIMBER, AND IRON ; consisting of 
 46 Plates from the Contract Drawings or Admeasurement of select 
 Works. By W. Davis Haskoll, C.E. Second Edition, with 
 the addition of 554 Estimates, and the Practice of Setting out Works, 
 illustrated with 6 pages of Diagrams. Imp. 4to, price 2/. I2J-. 6d. 
 lialf-morocco. 
 
 “ One of the very few works extant descending to the level of ordinary routipe, and 
 treating on the common every-day practice of the railway engineer. ... A work of 
 the present nature by a man of Mr. Haskoll’s experience, must prove invaluable to 
 hundreds. The tables of estimates appended to this edition will considerably enhance 
 its value.” — Engineering. 
 
 “ We must express our cordial approbation of the work just issued by Mr. Haskoll. 
 .... Besides examples of the best and most economical forms of bridge construction, 
 the author has compiled a series of estimates which cannot fail to be of service to the 
 practical man. . . . The examples Of bridges are selected from those of the most notable 
 construction on the different lines of the kingdom, and their details may consequently 
 be safely followed.” — Railway News. 
 
 “ A very valuable volume, and may be added usefully to the library of every young 
 engineer. ” — Builder. 
 
 “ An excellent selection of examples, very carefully drawn to useful scales of pro- 
 portion. ” — A rtizan. 
 
 Mathematical and Drawing Instruments. 
 
 A TREATISE ON THE PRINCIPAL MATHEMATICAL 
 AND DRAWING INSTRUMENTS employed by the Engineer, 
 Architect, and Surveyor. By Frederick W. Simms, F.G.S., M. 
 Inst. C.E., Author of “Practical Tunnelling,” &c. &c. Third 
 Edition, with a Description of the Theodolite, together with Instruc- 
 tions in Field Work, compiled for the use of Students on commenc- 
 ing practice. With numerous Cuts. i2mo, price 3s. 6d. cloth. 
 
 Oblique Arches. 
 
 A PRACTICAL TREATISE ON THE CONSTRUCTION of 
 OBLIQUE ARCHES. By John Hart. Third Edition, with 
 Plates. Imperial 8vo, price 8s. cloth. 
 
 %* The small remaining stock of this work , which has been un- 
 obtainable for some time , has just been purchased by Lockwood St Co. 
 
 Oblique Bridges. 
 
 A PRACTICAL and THEORETICAL ESSAY on OBLIQUE 
 BRIDGES, with 13 large folding Plates. By Geo. Watson 
 Buck, M. Inst. C.E. Second Edition, corrected by W. PI. 
 Barlow, M. Inst. C.E. Imperial 8vo, 12 s. cloth. 
 
 “The standard text-book for all engineers regarding skew arches, is Mr. Buck’s 
 treatise, and it would be impossible to consult a better.” — Engitieer. 
 
 “A very complete treatise on the subject, re-edited by Mr. Barlow, who has added 
 to it a method of making the requisite calculations without the use of trigonometrical 
 fo rmulae. ’ ' — Builder. 
 
14 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 IVeale’s Series of Rudimentary Works. 
 
 These highly popular and cheap Series of Books, now comprising 
 upwards of Two Hundred and Fifty distinct Works in almost every 
 department of Science, Art, and Education, are recommended to the 
 notice of Engineers, Architects, Builders, Artizans, and Students gene- 
 rally, as well as to those interested in Workmen’s Libraries, Free 
 Libraries, Literary and Scientific Institutions, Colleges, Schools, Science 
 Classes, &c., &c. Lists of the several Series may be had on application 
 to LOCKWOOD & CO. 
 
 The following is a Selection of the Works on Civil Engineering : — 
 STEAM ENGINE. By Dr. Lardneb. ij. 
 
 TUBULAR AND IRON GIRDER BRIDGES, including the Britannia and 
 Conway Bridges. By G. D. Dempsey, is. 6d. 
 
 STEAM BOILERS, their Construction and Management. By R. Armstrong. 
 With Additions, is. 6 d. 
 
 RAILWAY CONSTRUCTION. By Sir M. Stephenson. New Edition, 2 *. 6 d. 
 STEAM ENGINE, Mathematical Theory of. By T. Baker, is. 
 
 ENGINEER’S GUIDE TO THE ROYAL AND MERCANTILE NAVIES. 
 
 By a Practical Engineer. Revised by D. F. McCarthy. 3.?. 
 LIGHTHOUSES, their Construction and Illumination. By Alan Stevenson. 3 s. 
 CRANES AND MACHINERY FOR RAISING HEAVY BODIES, the Art of 
 Constructing. By J. Glynn, ij. 
 
 CIVIL ENGINEERING. By H. Law and G. R. Burnell. New Edition, 3 s . 
 DRAINING DISTRICTS AND LANDS. By G. D. Dempsey, is Ad. ) The 
 DRAINING AND SEWAGE OF TOWNS AND BUILDINGS. By f2v0ls.ini, 
 G. D. Dempsey. 2 s. J SE- 
 
 WELL-SINKING, BORING, AND PUMP WORK. By J. G. Swindell ; 
 Revised by G. R. Burnell, is. 
 
 ROAD-MAKING AND MAINTENANCE OF MACADAMISED ROADS. 
 By Gen. Sir J. Burgoyne. is. 6d. 
 
 AGRICULTURAL ENGINEERING, BUILDINGS, MOTIVE POWERS, 
 FIELD MACHINES, MACHINERY AND IMPLEMENTS. By G. H. 
 Andrews, C.E. 3 s. 
 
 ECONOMY OF FUEL. By T. S. Prideaux. ir. 6 d. 
 
 EMBANKING LANDS FROM THE SEA. By J. Wiggins. 2j. 
 
 WATER POWER, as applied to Mills, &c. By J. Glynn. 2 s. 
 
 GAS WORKS, AND THE PRACTICE OF MANUFACTURING AND 
 DISTRIBUTING COAL GAS. By S. Hughes, C.E. 3 s . 
 
 WATERWORKS FOR THE SUPPLY OF CITIES AND TOWNS. By S. 
 Hughes, C.E. 3 j. 
 
 SUBTERRANEOUS SURVEYING, AND THE MAGNETIC VARIATION 
 OF THE NEEDLE. By T. Fenwick, with Additions by T. Baker. 2 s. 6 d. 
 CIVIL ENGINEERING OF NORTH AMERICA. By D. Stevenson. 3 j. 
 HYDRAULIC ENGINEERING. By G. R. Burnell. 3s . 
 
 RIVERS AND TORRENTS, with the Method of Regulating their Course and 
 Channels, Navigable Canals, &c., from the Italian of Paul Frisi. 2 s. 6 d. 
 COMBUSTION OF COAL AND THE PREVENTION OF SMOKE. By 
 C. Wye Williams, M.I. C.E. 3 s. 
 
 WATER POWER, as applied to Mills, &c. By J. Glynn. 2 s. 
 
 MARINE ENGINES and STEAM VESSELS and the SCREW. By Robert 
 Murray, C.E. Fifth Edition. 3 s. 
 
 ENGINEER’S GUIDE TO THE ROYAL AND MERCANTILE NAVIES. 
 By a Practical Engineer. Revised by D. F. McCarthy. 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 15 
 
 ARCHITECTURE, &c. 
 
 Construction. 
 
 THE SCIENCE of BUILDING : an Elementary Treatise on 
 the Principles of Construction. Especially adapted to the Re- 
 quirements of Architectural Students. By E. Wyndham Tarn, 
 M.A., Architect. Illustrated with 47 Wood Engravings. Demy 
 8vo, price 8s. 6d. cloth. [Recently published. 
 
 “ A very valuable book, which we strongly recommend to all students.” — Builder. 
 
 “ A modest and valuable book of reference for the student. . . . The formulae will 
 be found perfectly intelligible and available by the class for whom they are intended.” — 
 A thenceum. 
 
 “While Mr. Tarn’s valuable little volume is quite sufficiently scientific to answer 
 the purposes intended, it is written in a style that will deservedly make it popular. 
 The diagrams are numerous and exceedingly well executed, and the treatise does 
 credit alike to the author and the publisher.” — Engmeer , Feb. 17, 1871. 
 
 “No architectural student should be without this hand-book of constructional 
 knowledge.” — A rchitect. 
 
 “The book is very far from being a mere compilation ; it is an able digest of 
 information which is only to be found scattered through various works, and contains 
 more really original writing than many putting forth far stronger claims to originality. 
 .... Mr. Tarn has done his work exceedingly well, and he has produced a book 
 which ought to earn him the thanks of all architectural students.” — E 7 igineering. 
 
 Beatoiis P ocket Estimator . 
 
 THE POCKET ESTIMATOR FOR THE BUILDING 
 TRADES, being an easy method of estimating the various parts 
 of a Building collectively, more especially applied to Carpenters* 
 and Joiners’ work, priced according to the present value of material 
 and labour. By A. C. Beaton, Author of ‘ Quantities and 
 Measurements.’ Numerous Woodcuts. \_In the Press. 
 
 Villa Architecture. 
 
 A HANDY BOOK of VILLA ARCHITECTURE ; being a 
 Series of Designs for Villa Residences in various Styles. With 
 Detailed Specifications and Estimates. By C. Wickes, Architect, 
 Author of “ The Spires and Towers of the Mediaeval Churches of 
 England,” &c. First Series, consisting of 30 Plates ; Second 
 Series, 31 Plates. Complete in 1 vol., 4to, price 2/. ioa half 
 morocco. Either Series separate, price 1 l. *js. each, half morocco. 
 “ The whole of the designs bear evidence of their being the work of an artistic 
 architect, and they will prove very valuable and suggestive to architects, students, and 
 amateurs.” — Building News. 
 
 The Architect' s Guide. 
 
 THE ARCHITECT’S GUIDE ; or, Office and Pocket Com- 
 panion for Engineers, Architects, Land and Building Surveyors, 
 Contractors, Builders, Clerks of Works, &c. By W. Davis 
 Haskoll, C.E., R. W. Billings, Architect, F. Rogers, and 
 P. Thompson. With numerous Experiments by G. Rennie, 
 C.E., &c. Woodcuts, i2mo, cloth, price 3s. 6d. 
 
 Vitruvius' A rchitecture. 
 
 THE ARCHITECTURE OF MARCUS VITRUVIUS 
 POLLIO. Translated by Joseph Gwilt, F.S.A., F.R.A.S. 
 Numerous Plates. i2mo, cloth limp, price $s. 
 
16 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 The Young Architect' s Book. 
 
 HINTS TO YOUNG ARCHITECTS ; comprising Advice to 
 those who, while yet at school, are destined to the Profession ; to 
 such as, having passed their pupilage, are about to travel ; and to 
 those who, having completed their education, are about to practise. 
 By George Wightwick, Architect, Author of “The Palace of 
 Architecture,” &c. &c. Second Edition. With numerous Wood- 
 cuts. 8 vo, 7 x., extra cloth. 
 
 Drawing for Builders and Students . 
 
 PRACTICAL RULES ON DRAWING for the OPERATIVE 
 BUILDER and YOUNG STUDENT in ARCHITECTURE. 
 By George Pyne, Author of a “ Rudimentary Treatise on Per- 
 spective for Beginners.” With 14 Plates, 4to, Js. 6d ., boards. 
 Contents.— I. Practical Rules on Drawing — Outlines. II. Ditto — the Grecian 
 and Roman Orders. III. Practical Rules on Drawing — Perspective. IV. Practical 
 Rules on Light and Shade. V. Practical Rules on Colour, &c. &c. 
 
 Drawing for Engineers, Cfc. 
 
 THE WORKMAN’S MANUAL OF ENGINEERING 
 DRAWING. By John Maxton, Instructor in Engineering 
 Drawing, South Kensington. With upwards of 300 Plates and 
 Diagrams. i2mo, cloth, strongly bound, 4 s. 6d. [This day. 
 
 Cottages , Villas, and Country Houses. 
 
 DESIGNS and EXAMPLES of COTTAGES, VILLAS, and 
 COUNTRY HOUSES ; being the Studies of several eminent 
 Architects and Builders ; consisting of Plans, Elevations, and Per- 
 spective Views ; with approximate Estimates of the Cost of each. 
 In 4to, with 67 plates, price 1 /. u., cloth. 
 
 Weale's Builder s and Contractor s Price Book. 
 
 THE BUILDER’S AND CONTRACTOR’S PRICE BOOK 
 (Lockwood & Co.’s, formerly Weale’s). Published Annually. 
 Containing Prices for Work in all branches of the Building Trade, 
 with Items numbered for easy reference, and an Appendix of 
 Tables, Notes, and Memoranda, arranged to afford detailed infor- 
 mation, commonly required in preparing Estimates, &c. Originally 
 Edited by the late Geo. R. Burnell, C.E., &c. i2mo, 4s., cloth. 
 
 “A multitudinous varietv of useful information for builders and contractors 
 
 With its aid the prices for all work connected with the building trade may be esti- 
 mated. Building News. 
 
 “ Carefully revised, admirably arranged, and clearly printed, it offers at a glance a 
 ready method of preparing an estimate or specification upon a basis that is unquestion- 
 able. A reliable book of reference in the event of a dispute between employer and 
 employed. ” — Engineer. 
 
 “ Well done and reliable. It is the duty of a just critic to point out where any 
 improvement can be made in any work, but Mr. Burnell has anticipated all objections 
 in his clearly-printed book. We therefore recommend it to all branches of the pro- 
 fession. ” — English Mechanic. 
 
 “Mr. Burnell has omitted nothing from this work that could tend to render it 
 valuable to the builder or contractor.” — Mechanic's Magazine. 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 17 
 
 Handbook of Specifications. 
 
 THE HANDBOOK OF SPECIFICATIONS ; or, Practical 
 Guide to the Architect, Engineer, Surveyor, and Builder, in drawing 
 up Specifications and Contracts for Works and Constructions. 
 Illustrated by Precedents of Buildings actually executed by eminent 
 Architects and Engineers. Preceded by a Preliminary Essay, and 
 Skeletons of Specifications and Contracts, &c., &c., and explained 
 by numerous Lithograph Plates and Woodcuts. By Professor 
 Thomas L. Donaldson, President of the Royal Institute of British 
 Architects, Professor of Architecture and Construction, University 
 College, London, M.I. B.A., Member of the various European 
 Academies of the Fine Arts. With A Review of the Law of 
 Contracts, and of the Responsibilities of Architects, Engineers, 
 and Builders. By W. Cunningham Glen, Barrister-at-Law, of 
 the Middle Temple. 2 vols., 8vo, with upwards of 1100 pp. of 
 text, and 33 Lithographic Plates, cloth, 2/. 2 s. (Published at 4 /. ) 
 
 “ In these two volumes of 1,100 pages (together), forty-four specifications of executed 
 works are given, including the specifications for parts of the new Houses of Parliament, 
 hy Sir Charles Barry, and for the "new Royal Exchange, by Mr. Tite, M.P. The 
 latter, in particular, is a very complete and remarkable document. It embodies, to a 
 great extent, as Mr. Donaldson mentions, ‘ the bill of quantities, with the description 
 of the works,’ and occupies more than 100 printed pages. 
 
 “Amongst the other known buildings, the specifications of which are given, are 
 the Wiltshire Lunatic Asylum (Wyatt and Brandon) ; Tothill Fields Prison (R. Abra- 
 ham) ; the City Prison, Holloway (Bunning) ; the High School, Edinburgh (Hamilton) ; 
 Clothworkers’ Hall, London (Angel) ; Wellington College, Sandhurst (J. Shaw) ; 
 Houses in Grosvenor Square, and elsewhere ; St. George’s Church, Doncaster 
 (Scott) ; several works of smaller size by the Author, including Messrs. Shaw’s Ware- 
 house in Fetter Lane, a very successful elevation ; the Newcastle-upon-Tyne Railway 
 Station (J. Dobson) ; new Westminster Bridge (Page) ; the High Level Bridge, New- 
 castle (R. Stephenson) ; various works on the Great Northern Railway (Brydone) ; 
 and one French specification for Houses in the Rue de Rivoli, Paris (MM. Armand, 
 Hittorff, Pellechet, and Rohault de Fleury, architects). The last is a very elaborate 
 composition, occupying seventy 'pages. The majority of the specifications have illus- 
 trations in the shape of elevations and plans. 
 
 “ We are most glad to have the present work. It is valuable as a record, and more 
 valuable still as a book of precedents. 
 
 “ About 140 pages of the second volume are appropriated to an exposition of the 
 law in relation to the legal liabilities of engineers, architects, contractors, and builders, 
 by Mr. W. Cunningham Glen, Barrister-at-law ; intended rather for those persons 
 than for the legal practitioner. Suffice it, in conclusion, to say in words what our 
 readers will have gathered for themselves from the particulars we have given, that 
 Donaldson’s Handbook of Specifications must be bought by all architects.” — Builder . 
 
 Mechanical Engineering. 
 
 A PRACTICAL TREATISE ON MECHANICAL ENGI- 
 NEERING: comprising Metallurgy, Moulding, Casting, Forging, 
 Tools, Workshop Machinery, Mechanical Manipulation, Manufac- 
 ture of the Steam Engine, &c. &c. With an Appendix on the 
 Analysis of Iron and Iron Ore, and Glossary of Terms. By Francis 
 Campin, C.E. Illustrated with 91 Woodcuts and 28 Plates of 
 Slotting, Shaping, Drilling, Punching, Shearing, and Riveting 
 Machines — Blast, Refining, and Reverberatory Furnaces — Steam 
 Engines, Governors, Boilers, Locomotives, &c. Demy 8vo, cloth, 
 price 12 s. 
 
i8 
 
 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 Grantham s Iron Ship- Building , enlarged. 
 
 ON IRON SHIP-BUILDING ; with Practical Examples and 
 Details. Fifth Edition. Imp. 4to, boards, enlarged from 24 to 40 
 Plates (21 quite new), including the latest Examples. Together 
 with separate Text, i2mo, cloth limp, also considerably enlarged, 
 By John Grantham, M. Inst. C.E., &c. Price 2/. 2 s. complete. 
 
 Description of Plates . 
 
 1. Hollow and Bar Keels, Stem and 
 
 Stern Posts. [Pieces. 
 
 2. Side Frames, Floorings, and Bilge 
 
 3. Floorings continued- — Keelsons, Deck 
 
 Beams, Gunwales, and Stringers. 
 
 4. Gunwales continued — Lower Decks, 
 
 and Orlop Beams. 
 
 4 a. Gunwales and Deck Beam Iron. 
 
 5. Angle-Iron, T Iron, Z Iron, Bulb 
 
 Iron, as Rolled for Building. 
 
 6. Rivets, shown in section, natural size ; 
 
 Flush and Lapped Joints, with 
 Single and Double Riveting. 
 
 7. Plating, three plans ; Bulkheads and 
 
 Modes of Securing them. 
 
 8. Iron Masts, with Longitudinal and 
 
 Transverse Sections. 
 
 9. Sliding Keel, Water Ballast, Moulding 
 
 the Frames in Iron Ship Building, 
 Levelling Plates. 
 
 10. Longitudinal Section, and Half- 
 
 breadth Deck Plan of Large Vessels 
 on a reduced Scale. 
 
 11. Midship Sections of Three Vessels. 
 
 12. Large Vessel , showing Details — Fore 
 
 End in Section, and End View, 
 with Stern Post, Crutches, &c. 
 
 13. Large Vessel, showing Details — A fter 
 
 End in Section, with End View, 
 Stern Frame for Screw, and Rudder. 
 
 14. L arge Vessel, showing De tails — Mid- 
 
 ship Section, half breadth. 
 
 15. Machines for Punching and Shearing 
 
 Plates and Angle-Iron, and for 
 Bending Plates ; Rivet Hearth. 
 
 15#. Beam-Bending Machine, Indepen- 
 dent Shearing, Punching and Angle- 
 Iron Machine. 
 
 15& Double Lever Punching and Shearing 
 Machine, arranged for cutting 
 Angle and T Iron, with Dividing 
 Table and Engine. 
 
 16. Machines. — Garforth’s Riveting Ma- 
 
 chine, Drilling and Counter-Sinking 
 Machine. 
 
 1 6 a. Plate Planing Machine. 
 
 1 7. Air Furnace for Heating Plates and 
 
 Angle-Iron : Various Tools used in 
 Riveting and Plating. 
 
 18. Gunwale ; Keel and Flooring ; Plan 
 
 for Sheathing with Copper. 
 
 18 a. Grantham’s Improved Plan of Sheath- 
 ing Iron Ships with Copper. 
 
 19. Illustrations of the Magnetic Condi- 
 
 tion of various Iron Ships. 
 
 20. Gray’s Floating Compass and Bin- 
 
 nacle, with Adjusting Magnets, &c. 
 
 21. Corroded Iron Bolt in Frame of 
 
 Wooden Ship ; Jointing Plates. 
 22-4. Great Eastern — Longitudinal Sec- 
 tions and Half-breadth Plans — Mid- 
 ship Section, with Details — Section 
 in Engine Room, and Paddle Boxes. 
 25-6. Paddle Steam Vessel of Steel. 
 
 27. Scarbrough — Paddle Vessel of Steel. 
 28-9. Proposed Passenger Steamer. 
 
 30. Persian — Iron Screw Steamer. 
 
 31. Midship Section of H.M. Steam 
 
 Frigate, Warrior. 
 
 32. Midship Section of H.M. Steam 
 
 Frigate, Hercules. 
 
 33. Stem, Stern, and Rudder of H.M. 
 
 Steam Frigate, Belleropho?i. 
 
 34. Midship Section of H. M. Troop Ship, 
 
 Serapis. 
 
 35. Iron Floating Dock. 
 
 “An enlarged edition of an elaborately illustrated work.” — Builder , July 11, 1868. 
 
 “ This edition of Mr. Grantham’s work has been enlarged and improved, both with 
 respect to the text and the engravings being brought down to the present period . . 
 The practical operations required in producing a ship are described and illustrated with 
 care and precision.” — Mechanics' Magazine , July 17, 1868. 
 
 “ A thoroughly practical work, and every question of the many in relation to iron 
 shipping which admit of diversity of opinion, or have various and conflicting personal 
 interests attached to them, is treated with sober and impartial wisdom and good sense. 
 . . . . As good a volume for the instruction of the pupil or student of iron naval 
 
 architecture as can be found in any language.” — Practical Mechanic's Journal, 
 August, 1868. 
 
 “ A very elaborate work. . . . It forms a most valuable addition to the history 
 
 of iron shipbuilding, while its having been prepared by one who has made the subject 
 his study for many years, and whose qualifications have been repeatedly recognised, 
 will recommend it as one of practical utility to all interested in shipbuilding.” — Army 
 and Navy Gazette , July 11, 1868. 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 19 
 
 CARPENTRY, TIMBER, &c. 
 
 ♦ 
 
 Tredgold' s Carpentry , new & enlarged Edition. 
 
 THE ELEMENTARY PRINCIPLES OF CARPENTRY : 
 a Treatise on the Pressure and Equilibrium of Timber Framing, the 
 Resistance of Timber, and the Construction of Floors, Arches, 
 Bridges, Roofs, Uniting Iron and Stone with Timber, &c. To which 
 is added an Essay on the Nature and Properties of Timber, & c., 
 with Descriptions of the Kinds of Wood used in Building ; also 
 numerous Tables of the Scantlings of Timber for different purposes, 
 the Specific Gravities of Materials, &c. By Thomas Tredgold, 
 C.E. Edited by Peter Barlow, F.R.S. Fifth Edition, cor- 
 rected and enlarged. With 64 Plates (1 i of which now first appear 
 in this edition), Portrait of the Author, and several Woodcuts. In 
 1 vol., 4to, published at il. 2s., reduced to 1 /. 5 a, cloth. 
 
 “‘Tredgold’s Carpentry’ ought to be in every architect’s and every builder’s 
 library, and those who do not already possess it ought to avail themselves of the new 
 issue.” — Builder , April 9, 1870. 
 
 A work whose monumental excellence must commend it wherever skilful car- 
 pentry is concerned. The Author’s principles are rather confirmed than impaired by 
 time, and, as now presented, combine the surest base with the most interesting display 
 of progressive science. The additional plates are of great intrinsic value.” — Building 
 News, Feb. 25, 1870. 
 
 “‘Tredgold’s Carpentry’ has ever held a high position, and the issue of the fifth 
 edition, in a still more improved and enlarged form, will give satisfaction to a very 
 large number of artisans who desire to raise themselves in their business, and who 
 seek to do so by displaying a greater amount of knowledge and intelligence than their 
 fellow-workmen. It is as complete a work as need be desired. To the superior 
 workman the volume will prove invaluable ; it contains treatises written in language 
 which he will readily comprehend.” — Mining Journal , Feb. 12, 1870. 
 
 Grandy s Timber Tables . 
 
 THE TIMBER IMPORTER’S, TIMBER MERCHANT’S, 
 and BUILDER’S STANDARD GUIDE. By Richard E. 
 Grandy. Comprising : — An Analysis of Deal Standards, Home 
 and Foreign, with comparative Values and Tabular Arrangements 
 for Fixing Nett Landed Cost on Baltic and North American Deals, 
 including all intermediate Expenses, Freight, Insurance, Duty, &c., 
 & c. ; together with Copious Information for the Retailer and 
 Builder. i2mo, price 7 s. 6d. cloth. 
 
 “ Everything it pretends to be : built up gradually, it leads one from a forest to a 
 trenail, and throws in, as a makeweight, a host of material concerning bricks, columns, 
 cisterns, &c. — all that the class to whom it appeals requires.” — English Mechanic. 
 
 “ The only difficulty we have is as to what is not in its pages. What we have tested 
 of the contents, taken at random, is invariably correct.” — Illustrated Builders Journal. 
 
 Tables for Packing-Case Makers. 
 
 PACKING-CASE TABLES ; showing the number of Superficial 
 Feet in Boxes or Packing-Cases, from six inches square and 
 upwards. Compiled by William Richardson, Accountant. 
 Oblong 4to, cloth, price 3 s. 6d. 
 
 “Will save much labour and calculation to packing-case makers and those who use 
 packing-cases.” — Grocer. “ Invaluable labour-saving tables.” — Ironmonger. 
 
20 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 Nicholson s Carpenter s Guide. 
 
 THE CARPENTER’S NEW GUIDE ; or, BOOK of LINES 
 for CARPENTERS : comprising all the Elementary Principles 
 essential for acquiring a knowledge of Carpentry. Founded on the 
 late Peter Nicholson’s standard work. A new Edition, revised 
 by Arthur Ashpitel, F.S.A., together with Practical Rules on 
 Drawing, by George Pyne. With 74 Plates, 4to, 1 /. is. cloth. 
 
 Dowsing' s Timber Merchant' s Companion. 
 
 THE TIMBER MERCHANT’S AND BUILDER’S COM- 
 PANION ; containing New and Copious Tables of the Reduced 
 Weight and Measurement of Deals and Battens, of all sizes, from 
 One to a Thousand Pieces, and the relative Price that each size 
 bears per Lineal Foot to any given Price per Petersburgh Standard 
 Hundred ; the Price per Cube Foot of Square Timber to any given 
 Price per Load of 50 Feet; the proportionate Value of Deals and 
 Battens by the Standard, to Square Timber by the Load of 50 Feet ; 
 the readiest mode of ascertaining the Price of Scantling per Lineal 
 Foot of any size, to any given Figure per Cube Foot. Also a 
 variety of other valuable information. By William Dowsing, 
 Timber Merchant. Second Edition. Crown 8vo, 3.5*. cloth. 
 
 “ Everything is as concise and clear as it can possibly be made. There can be no 
 doubt that every timber merchant and builder ought to possess it, because such possession 
 would, with use, unquestionably save a very great deal of time, and, moreover, ensure 
 perfect accuracy in calculations. There is also another class besides these who ought 
 to possess it ; we mean all persons engaged in carrying wood, where it is requisite to 
 ascertain its weight. Mr. Dowsing’s tables provide an easy means of doing this. 
 Indeed every person who has to do with wood ought to have it .” — Hull Advertiser. 
 
 Mechanic s Workshop Companion. 
 
 THE OPERATIVE MECHANIC’S WORKSHOP COM- 
 PANION, and THE SCIENTIFIC GENTLEMAN’S PRAC- 
 TICAL ASSISTANT ; comprising a great variety of the most 
 useful Rules in Mechanical Science ; with numerous Tables of Prac- 
 tical Data and Calculated Results. By W. Templeton, Author 
 of “The Engineer’s, Millwright’s, and Machinist’s Practical As- 
 sistant.” Tenth Edition, with Mechanical Tables for Operative 
 Smiths, Millwrights, Engineers, &c. ; together with several Useful 
 and Practical Rules in Hydraulics and Hydrodynamics, a variety 
 of Experimental Results, and an Extensive Table of Powers and 
 Roots. 11 Plates. i2mo, 5 s. bound. [Just published. 
 
 “ As a text-book of reference, in which mechanical and commercial demands are 
 judiciously met, Templeton’s Companion stands unrivalled.” — Mechanics' Magazine. 
 
 “ Admirably adapted to the wants of a very large class. It has met with great 
 success in the engineering workshop, as we can testify ; and there are a great many 
 men who, in a great measure, owe their rise in life to this little work .” — Building News. 
 
 MECHANICS, 
 
 >■ 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 21 
 
 Engineer s Assistant. 
 
 THE ENGINEER’S, MILLWRIGHT’S, and MACHINIST’S 
 PRACTICAL ASSISTANT ; comprising a Collection of Useful 
 Tables, Rules, and Data. Compiled and Arranged, with Original 
 Matter, by W. Templeton. 4th Edition. i8mo, 2 s. 6 d. cloth. 
 
 ** So much varied information compressed into so small a space, and published at a 
 price which places it within the reach of the humblest mechanic, cannot fail to com- 
 mand the sale which it deserves. With the utmost confidence we commend this book 
 to the attention of our readers.” — Mecha?iics' Magazine . 
 
 “ Every mechanic should become the possessor of the volume, and a more suitable 
 present to an apprentice to any of the mechanical trades could not possibly be made.” 
 — Building News. 
 
 Designing , Measuring , and Valuing. 
 
 THE STUDENT’S GUIDE to the PRACTICE of ME A- 
 SURING, and VALUING ARTIFICERS’ WORKS ; containing 
 Directions for taking Dimensions, Abstracting the same, and bringing 
 the Quantities into Bill, with Tables of Constants, and copious 
 Memoranda for the Valuation of Labour and Materials in the res- 
 pective Trades of Bricklayer and Slater, Carpenter and Joiner, 
 Painter and Glazier, Paperhanger, &c. With 43 Plates and Wood- 
 cuts. Originally edited by Edward Dobson, Architect. New 
 Edition, re-written, with Additions on Mensuration and Construc- 
 tion, and several useful Tables for facilitating Calculations and 
 Measurements. By E. Wyndham Tarn, M.A., Architect. 8vo, 
 ioj'. 6 d. cloth. {Just published. 
 
 “ This useful book should be in every architect’s and builder’s office. It contains 
 a vast amount of information absolutely necessary to be known.” — Fhe Irish Biulder. 
 
 “ The book is well worthy the attention of the student in architecture and surveying, 
 as by the careful study of it his progress in his profession will be much facilitated.” — 
 Mining Journal , Feb. n, 1871. 
 
 “ We have failed to discover anything connected with the building trade, from ex- 
 cavating foundations to bell-hanging, that is not fully treated upon in this valuable 
 work.” — The Artizan, March, 1871. 
 
 “ Mr. Tarn has well performed the task imposed upon him, and has made many 
 further and valuable additions, embodying a large amount of information relating to 
 the technicalities and modes of construction employed in the several branches of the 
 
 building trade From the extent of the information which the volume 
 
 embodies, and the care taken to secure accuracy in every detail, it cannot fail to prove 
 of the highest value to students, whether training in the offices of provincial surveyors, 
 or in those of London practitioners.” — Colliery Guardian , February 10th, 1871. 
 
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 have especially augmented its value to students. Finally, it is only just to the pub- 
 lishers to add that the book has been got up in excellent style, the typography being 
 bold and clear, and the plates very well executed.” — Enguieering, March 24, 1871. 
 
 Superficial Measurement. 
 
 THE TRADESMAN’S GUIDE TO SUPERFICIAL MEA- 
 SU REM ENT. Tables calculated from 1 to 200 inches in length, 
 by 1 to 108 inches in breadth. For the use of Architects, Surveyors, 
 Engineers, Timber Merchants, Builders, &c. By James Haw- 
 kings. Fcp. 3J-. 6 d. cloth. 
 
22 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 MATHEMATICS, &c. 
 
 Gregory s Practical Mathematics. 
 
 MATHEMATICS for PRACTICAL MEN ; being a Common- 
 place Book of Pure and Mixed Mathematics. Designed chiefly 
 for the Use of Civil Engineers, Architects, and Surveyors. Part I. 
 Pure Mathematics— comprising Arithmetic, Algebra, Geometry, 
 Mensuration, Trigonometry, Conic Sections, Properties of Curves. 
 Part II. Mixed Mathematics — comprising Mechanics in general, 
 Statics, Dynamics, Hydrostatics, Hydrodynamics, Pneumatics, 
 Mechanical Agents, Strength of Materials. With an Appendix of 
 copious Logarithmic and other Tables. By Olinthus Gregory, 
 LL.D., F.R. A.S. Enlarged by Henry Law, C.E. 4th Edition, 
 carefully revised and corrected by J. R. Young, formerly Profes- 
 sor of Mathematics, Belfast College; Author of “A Course of 
 Mathematics,” &c. With 13 Plates. Medium 8vo, 1 /. Is. cloth. 
 
 “ As a standard work on mathematics it has not been excelled.” — Artizan. 
 
 “ The engineer or architect will here find ready to his hand, rules for solving nearly 
 every mathematical difficulty that may arise in his practice. As a moderate acquaint- 
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 proper understanding of the most useful portions of this book, the author very wisely 
 has devoted the first three chapters to those subjects, so that the most ignorant may be 
 enabled to master the whole of the book, without aid from any other. The rules are in 
 all cases explained by means of examples, in which every step of the process is clearly 
 worked out.” — Builder. 
 
 “ One of the most serviceable books to the practical mechanics of the country. . 
 
 The edition of 1847 was fortunately entrusted to the able hands of Mr. Law, who 
 revised it thoroughly, re-wrote many chapters, and added several sections to those 
 which had been rendered imperfect by advanced knowledge. On examining the various 
 and many improvements which he introduced into the work, they seem almost like a 
 new structure on an old plan, or rather like the restoration of an old ruin, not only to 
 its former substance, but to an extent which meets the larger requirements of modern 
 
 times In the edition just brought out, the work has again been revised by 
 
 Professor Young. He has modernised the notation throughout, introduced a few 
 paragraphs here and there, and corrected the numerous typographical errors which 
 have escaped the eyes of the former Editor. The book is now as complete as it is 
 
 possible to make it We have carried our notice of this book to a greater 
 
 length than the space allowed us justified, but the experiments it contains are so 
 interesting, and the method of describing them so clear, that we may be excused for 
 overstepping our limit. It is an instructive book for the student, and a Text- 
 book for him who having once mastered the subjects it treats of, needs occasionally to 
 refresh his memory upon them.” — Building News. 
 
 The Metric System. 
 
 A SERIES OF METRIC TABLES, in which the British 
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 “ Resolution 8. — That advantage will be derived from the recent publication of 
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 Bath. 
 
WORKS PUBLISHED BY LOCKWOOD & CO. 23 
 
 Inwood's Tables , greatly enlarged and improved. 
 
 TABLES FOR THE PURCHASING of ESTATES, Freehold, 
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 This edition ( the 1 8th) differs in many important particulars 
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 THEORY of COMPOUND INTEREST and ANNUITIES ; 
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24 
 
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 SCIENCE AND ART. 
 
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 AIDE-MEMOIRE to the MILITARY SCIENCES. Framed 
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 Field Fortification. 
 
 A TREATISE on FIELD FORTIFICATION, the ATTACK 
 of FORTRESSES, MILITARY, MINING, and RECON- 
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 A MANUAL of ELECTRICITY ; including Galvanism, Mag- 
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WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 2 
 
 Text-Book of Electricity. 
 
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 RUDIMENTARY MAGNETISM : being a concise exposition 
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 A SYNOPSIS of PRACTICAL PHILOSOPHY. By the Rev. 
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WORKS PUBLISHED BY LOCKWOOD & CO. 27 
 
 Geology and Genesis Harmonised. 
 
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 Delamotte' s Works on Illumination & A Iphabets. 
 
 A PRIMER OF THE ART OF ILLUMINATION ; for the 
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WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 29 
 
 AGRICULTURE, &c. 
 
 Youatt and Burris Complete Grazier. 
 
 THE COMPLETE GRAZIER, and FARMER’S and CATTLE- 
 BREEDER’S ASSISTANT. A Compendium of Husbandry. 
 By William Youatt, Esq., V.S. nth Edition, enlarged by 
 Robert Scott Burn, Author of “The Lessons of My Farm,” &c . 
 One large 8vo volume, 784 pp. with 215 Illustrations. 1 /. is. half-bd. 
 
 On the Breeding , Rearing , Fatte7iing, 
 and General Management of Neat Cattle. 
 — Introductory View of the different Breeds 
 of Neat Cattle in Great Britain. — Com- 
 parative View of the different Breeds of 
 Neat Cattle. — General Observations on 
 Buying and Stocking a Farm with Cattle. 
 — The Bull.— The Cow. — Treatment and 
 Rearing of Calves. — Feeding of Calvesfor 
 Veal. — Steers and Draught Oxen. — Graz- 
 ing Cattle. — Summer Soiling Cattle. — 
 Winter Box and Stall-feeding Cattle. — 
 Artificial Food for Cattle. — Preparation 
 of Food. — Sale of Cattle. 
 
 On the Eco7iomy and Management of 
 the Dairy . — Milch Kine. — Pasture and 
 other Food best calculated for Cows, as 
 it regards their Milk. — Situation and 
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 proper Dairy Utensils. — Management of 
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 and Comparative View of the different 
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 Training of Colts. — Age, Qualifications, 
 and Sale of Horses. — Maintenance and 
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 Merits of Draught Oxen and Horses. — 
 Asses and Mules. 
 
 On the Breeding, Rearing, and Fat- 
 tening of Sheep. — Introductory and Com- 
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 Management of Sheep. — Treatment and 
 Rearing of House-lambs, Feeding of Sheep, 
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 Feeding and Fattening of Swine. — Curing 
 Pork and Bacon. 
 
 On the Diseases of Cattle. — Diseases 
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 Diseases of Lambs. — Diseases Incident to 
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 mestic Fowls, Pigeons, &c. — Palmipedes, 
 or Web-footed kinds. — Diseases of Fowls. 
 
 On Farm Offices and Implements of 
 Husbandry. — The Farm-house, the Farm- 
 yard, and its Offices. — Construction of 
 Ponds. — Farm Cottages. — Farm Imple- 
 ments. — Steam Cultivation. — Sowing Ma- 
 chines, and Manure Distributors. — Steam 
 Engines, Thrashing Machine's, Corn- 
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 On the Culture and Management oj 
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 — Fences. — Pasture Land. — Meadow 
 Land. — Culture of Grass Land. — Hay- 
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 to the Scythe and the Eradication of 
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 Irrigation. — Warping. 
 
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 tive Value of some Grasses and Roots as 
 Food for Cattle. 
 
 On Manures in General, and their 
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 System of Manuring. — Farm Accounts, 
 and Tables for Calculating Labour by the 
 Acre, Rood, &c., and by the Day, Week, 
 Month, &c. — Monthly Calendar of Work 
 to be done throughout the Year. — Obser- 
 vations on the Weather. — Index. 
 
 “ The standard, and text-book, with the farmer and grazier.” — Farmer's Magazine. 
 “ A valuable repertory of intelligence for all who make agriculture a pursuit, and 
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30 WORKS PUBLISHED BY LOCKWOOD & CO. 
 
 Scott Burn s Introduction to Farming. 
 
 THE LESSONS of MY FARM : a Book for Amateur Agricul- 
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